WO2025191242A1

WO2025191242A1 - Optical display device

Info

Publication number: WO2025191242A1
Application number: PCT/GB2025/050457
Authority: WO
Inventors: Jonathan Clark; James mills Yapp POLLARD
Original assignee: Innerscene Ltd
Current assignee: Innerscene Ltd
Priority date: 2024-03-09
Filing date: 2025-03-06
Publication date: 2025-09-18
Anticipated expiration: 2026-09-09
Also published as: GB202403430D0

Abstract

An optical display device arranged to create a perception of a sky scene, the optical display device comprising: an output aperture for output of output light; an output light generation system comprising a light source to generate output light and a diffuse light generation system to generate a diffuse sky light component from light from the light source, and; electrical circuitry to control the light source, wherein the electrical circuitry is configured to control the light source to emit output light with a CCT of a maximum of at least 12,000 K and a with a colour rendering index (CRI) of at least 80.

Description

OPTICAL DISPLAY DEVICE

TECHNICAL FIELD

The present disclosure relates generally to electrically operated optical display devices for creating an artificial sky light, wherein an observer experiences a perception of a sky scene when gazing into an output aperture of said device.

BACKGROUND

US11 143364B2 discloses a device to provide an artificial skylight. The device comprises a light source to project light into a panel diffuser, which emits the light as a diffuse skylight component. The device includes an arrangement to create an infinity edge, which is said to create an effect of the emitting surface of the device being detached from, and floating above (e.g., at infinity) a frame of the device. The frame may also include a shroud to closely resemble a skylight frame. Such a device may lack the realism of an actual skylight.

Therefore, in spite of the effort already invested in the development of said devices further improvements are desirable.

SUMMARY

[General Device]

The present disclosure provides an optical display device (which may be implemented as one or more individual devices) arranged to create a perception of a sky scene in output light, the optical display device comprising: an output light generation system, and; an output aperture for the output light. The sky scene may have the perception of distant depth, which may include infinite depth. In embodiments, the perception of distant/infinite depth is determined based on gaze vectors of the eyes of an observer (e.g. a observer with normal vision) having the same and/or a similar alignment when looking into the device as for looking at real life sky (e.g. a clear sky with or without the sun present).

In embodiments, the output light generation system comprises a light source to generate output light. In embodiments, the device comprises electrical circuitry to control the light source.

In embodiments, the output light generation system comprises a diffuse light generation system to generate a diffuse sky light component in the output light from the light source. A diffuse light generation system may provide an appearance of a real-life sky light component in the sky scene. In embodiments, the diffuse light generation system includes a waveguide with redirecting features to diffusively decouple light projected within the waveguide to the output aperture. In embodiments, the light source is optically coupled to the waveguide (e.g., at one or more side faces thereof).

In embodiments, the sky scene (e.g. the diffuse sky light component/output light) is uniform to the extent where it does not vary by more than 10% or 20% or 30% or 40% for any given circular area on the output aperture of 10 mm or 50 mm diameter over at least 90% of the output aperture in terms of one or more of: colour; diffusivity; luminance profile; intensity. In embodiments, the diffuse sky light component in the output light has a Lambertian distribution. Said uniformity may provide a distant/infinite depth perception.

In embodiments, the sky scene (e.g. the diffuse sky light component/output light) is absent of features (e.g. objects in the sky scene, which may include visual cues or other artifacts) with an apparent depth ZA either at the optical display device or within an apparent depth ZA of 5 or 10 or 20 times a physical depth ZD of the device. A lack of objects/cues which have such a nearfield position may provide a distant/infinite depth perception of the sky scene. For example, an LDC or like display provides an image at within the depth of the device, hence they do not provide a distant depth perception. ZA may be measured from the output aperture in a depth direction into the device. The device may produce features (e.g. clouds or other distant object) outside of the depth range to support the distant depth perception.

As used herein the term “absent” in respect of the features may refer to fully and/or substantially absent said features, e.g. there are insufficient features and/or insufficiently large features to cause an observer to focus on them. The observer may have normal vision and may be at a range of 30 cm, 50 cm or 1 m from the output aperture of the device.

In embodiments, ZA is measured by gaze vectors from eyes (e.g. with one eye at the first viewing position and another eye at the second viewing position) of an observer gazing into the output aperture converging on one of more of said features. A user may be subject to normal vision.

In embodiments, ZA is measured by vectors of a first camera and spatially separated second camera (e.g. with one camera at the first viewing position and another camera at the second viewing position) projecting into the output aperture converging on one of more of said features. In embodiments, a depth of the one or more features of the distant object component is characterised by a parallax shift (e.g. a displacement in apparent position) corresponding to the apparent depth ZA when observed from laterally displaced positions (e.g. the first and second viewing positions which may have the same depth measured from the output aperture but different line of slight vectors).

As used herein, the term “ZD” or “physical depth of the optical display device” may refer to a depth of the optical display device in a direction orthogonal to a plane of the output aperture. It may refer to a total dimension of the device in said direction. The depth may include all associated components of the device that form its depth, e.g. the output aperture, a housing and the components of an output light generation system. In embodiments, a total depth of the device is a minimum of 2 cm or 3 cm or 4 cm. In embodiments, a total depth of the device is a maximum of 7 cm or 10 cm or 20 cm or 30 cm or 40 cm. Any of the aforesaid maximums and minimums may be combined in a range.

As used herein, the term “ZA” may refer to a virtual location. ZA may comprise a perpendicular distance in the depth direction from the output aperture to a perceived depth of the or each feature. ZA may optionally also include a perpendicular distance in the counter depth direction from the output aperture to a line connecting the viewing positions.

In embodiments, the output light generation system comprises, a collimated light generation system arranged to generate a collimated sunlight component in the output light. A collimated light generation system may provide an appearance of a sun in the sky scene.

In embodiments, the output aperture comprises a transparent member. The output light is typically transmitted though the transparent member. In embodiments, the transparent member includes an interior face and an exterior face. The interior face may face the output light generation system and an exterior face may face away from the output light generation system, e.g., towards an observer gazing into said device. The output light is typically projected to the interior face, through the thickness of the transparent member, and from the exterior face. In embodiments, the output aperture comprises a frame. In embodiments, the frame extends around the output aperture, e.g., to define the output aperture.

[Melanopic]

In embodiments, the electrical circuitry is configured to control the light source to emit the diffuse skylight component in the output light with one or more of (including at least two of): a first distinct melanopic lux range at a first day time range, which is at least 180 or 200 or 250 melanopic lux; a second distinct melonic lux range at a second afternoon/evening time range, which is not more than 50 or 60 melanopic lux, and; a third distinct melanopic lux range at a third night time range, which is not more than 1 melanopic lux.

By implementing the device to emit said melanopic lux at said one or more time ranges, Circadian rhythms of an observer may be kept in sync by various cues from the melanopic lux, thus improving a realism of the device. For example; dung the first day time range said melanopic lux may promote alertness; dung the second afternoon/evening time range said melanopic lux may promote the body to reduce energy expenditure and prepare for rest, and; dung the third night time range said melanopic lux may promote rest. With such an arrangement combined with a device at creates an impression of a sky scene at distant/infinite depth, visual and therapeutic effects may be provided.

As used herein the term, “melanopic lux” may refer to an Equivalent Melanopic Lux (EML), and is a measurement of light's effects on the circadian cycle. An example calculation method is disclosed in Lucas et aL, "Measuring and using light in the melanopsin age." Trends in Neuroscience, Jan 2014. EML may be determined on a vertical plane at eye level of the occupant and/or may be measured on a vertical plane, 1.2 m above a floor. For example, to calculate an EML, the visual lux (L) designed for or measured in a building is multiplied by the melanopic ratio (R), hence EML = L x R. An example calculation process to the EML is provided by the Well Certification. As used herein the term, “melanopic ratio” may refer to a measure of an effectiveness of light in stimulating the melanopsin photoreceptors in the human eye, which play a role in regulating circadian rhythms and the sleep-wake cycle. The melanopic ratio may be calculated based on a spectral power distribution of light, taking into account the sensitivity of melanopsin to different wavelengths. Hence a melanopic ratio may be provided in relation to CCT. An example calculation process to the melanopic ratio is provided by the well certification, e.g. https://standard.wellcertified.eom/tables#melanopicRatio.

As used herein the term, “first day time range” may refer to generally morning hours, e.g. from 4.00, 5.00, 6.00, 7.00, 8.00 or 9.00, or sunrise to any of 12.00, 13.00, 14.00, 15.00 or to after midday sun.

As used herein the term, “second afternoon/evening time range” may refer to general afternoon and evening hours, e.g. from 12.00, 13.00, 14.00, 15.00 or to after midday sun to any of 19.00, 20.00, 21 .00 or 22.00 or sunset. As used herein the term, “third night time range” may refer to night time hours, e.g. from any of 19.00, 20.00, 21 .00 or 22.00 or sunset to any of 4.00, 5.00, 6.00, 7.00, 8.00 or 9.00, to sunrise.

In embodiments, the light source comprises a plurality of individual sources. In embodiments, the light sources are configured with a peak emission wavelength A of less than 550 or 560 or 570 - or 580 or 590 or 600 nm. In embodiments, the light source is absent a red light source (e.g. a red light emitting diode) and may comprise a peak wavelength of green or yellow light. With such an arrangement, it may be ensured that the output light has a high melanopic ratio/melanopic lux.

In embodiments, the light source comprises: a first white light source channel to emit a first colour point; a second coloured light source channel to emit a second colour point; a third coloured light source channel to emit a third colour point, which is different to the second colour point. The first and second coloured light source may have a colour point which is different to the white light source (e.g. it is coloured).

In embodiments, the light source is absent (including substantially absent) a red light source (e.g. there is no red light channel). For example, there may be no red LEDs, or a negligible number of red LEDs (e.g. less than 90 or 95%)

As used herein the term “channel” may refer to a dedicated arrangement of light sources (e.g. LEDs) that are arranged to produce a same colour of light. A channel may be individually controlled by the electrical circuitry to control a proportion of the colour that the channel produces in the output light/diffuse light component.

In embodiments, the light source comprises: the second coloured light source channel as a green or yellow light source, and; the third coloured light source channel a blue light source.

In embodiments, the light source comprises: a fourth white light source channel to emit a fourth colour point, which is different to the first colour point.

In embodiments, the light source comprises: a first white light emitting diode to emit a first colour point; a green light emitting diode a to emit a second colour point, and; a blue light emitting diode to emit a third colour point.

With such an arrangement, it may be ensured that the output light has a high melanopic ratio/melanopic lux. As used herein the term “colour point” may refer to a specific point on a chromaticity diagram, e.g. a coordinate on a 1931 CIE Chromaticity Diagram, or other colour space. As used herein the term “colour space” may refer to a specific organization of colours arranged in a dimensional space, e.g. as two, three or four dimensions. It may define a range of colours that can be represented and the relationships between them. Examples of which include: RGB (Red, Green, Blue), CMYK (Cyan, Magenta, Yellow, Black), and HSL/HSV (Hue, Saturation, Lightness/Value). A colour space may include intensity representation.

In embodiments, the green light emitting diode/green light source channel is configured to emit light with a wave band of 520 nm to 565 nm, both range extremities may be ± 5 % or ± 10 %. In embodiments, the blue light emitting diode/blue light source channel is configured to emit light with a wave band of 450 to 495 nm, both range extremities may be ± 5 % or ± 10 %. In embodiments, the yellow light emitting diode/yellow light source channel is configured to emit light with a wave band of 570 to 590 nm, both range extremities may be ± 5 % or ± 10 %.

In embodiments, the white light emitting diode/first white light source channel is configured to emit light with a wave band of 380 nm to 700 nm both range extremities may be ± 5 % or ± 10 %. Although the white light source may emit light in the red waveband it is not to be considered a red light source, since it does not solely emit light in the red waveband (e.g. 620 - 700 nm).

In embodiments, the blue light emitting diode/blue light source channel; is configured to emit light with a CCT of 10,000 K to 100,000 K or 10,000 K to 50,000 K. Higher CCTs may also be implemented.

In embodiments, the green light emitting diode/blue light source channel; is configured to emit light with a CCT of 4,000 K - 10,000 K or 4,000 K - 7,000 K.

In embodiments, the white light emitting diode/first white light source channel is configured to emit light with a CCT of 2,200K to 10,000K or above or 1400 K - 10000 K or 1400 K - 3000 K. In embodiments, the light source comprises a second white light emitting diode to emit a fourth colour point, which is different to the first colour point.

In embodiments, the light source comprises a second white light source channel to emit a fourth colour point, which is different to the first colour point.

In embodiments, the second white light emitting diode/fourth white light source channel is configured to emit light with a wave band of 380 nm to 700 nm both range extremities may be ± 5 % or ± 10 %. Although the white light source may emit light in the red waveband it is not to be considered a red light source, since it does not solely emit light in the red waveband (e.g. 620 - 700 nm).

By implement a second white light emitting diode/fourth whit light source channel with a different emission to the first light emitting diode a greater control of an overall colour point of the light source may be achieved, moreover the diffuse skylight component may have a high CRL The first white light source channel/light emitting diode and fourth white light source channel/ light emitting diode may emit a substantial amount of the total power of the diffuse skylight component, e.g. up to 60, 70, 80, 90 or 95% (which may be measured in radiant power or luminous power of the light or watts of the electrical energy supplied to the light source), with the blue and green (or yellow) emitting the remaining less power, and used for fine positioning of the colour of the output light at a target position on the curve. The blue light source and optionally the white light sources may provide the desired high CCT.

In embodiments, the fourth white light source channel/second white light emitting diode is configured to emit light with a CCT of 2,200K to 10,000K or above or 1800 K - 10000 K or 4000 K - 10000 K. In embodiments, the first white light emitting diode and/or the second light emitting diode is a phosphor converted light emitting diode.

In embodiments, the electrical circuitry is configured to control the light source (e.g. the channels of same colour light sources) to emit output light with a CCT of a maximum of at least 12,000 K or 15,000 K or 20,000 K or 30,000 K, which may be up to a maximum CCT of 2000,000 K 1000,000 K or 500,000 K or 100,000 K or 60,000 K or 50,000 K or 45,000 K. An unconventionally high CCT combined with a device at creates an impression of a sky scene at distant/infinite depth, may provide visual and therapeutic effects (e.g. a high melanopic lux).

In embodiments, the electrical circuitry is configured to control the light source (e.g. the channels of same colour light sources) to emit output light with a CCT of a minimum of 1000 K or 1500 K or 2000 K.

It will be appreciated that although the output light/diffuse skylight component may be controlled to emit a high CCT (e.g. 12,000 K or above), in other operating modes of the device a CCT lower than this may be implemented.

In embodiments, the electrical circuitry is configured to control the light source (e.g. the channels of same colour light sources) to emit output light with a melanopic ratio of a maximum of at least 1 .2 or 1 .4 or 1 .6, which may extend up to a maximum of 2, 3, 4 or 6. A high melanopic ratio may have a high stimulation/therapeutic effect.

In embodiments, the electrical circuitry implements one or more other time ranges with a melanopic lux above or below a threshold. Increasing a number of time ranges may improve resolution/customisability of a light profile.

In embodiments, a start time and/or end time (e.g. including a duration) are user adjustable for one or more of the: first time range; second time range; third time range; other time range. By implement time ranges that a user (e.g. an end user as opposed to a manufacturer) may control the device may provide improved realism/user customisation.

In embodiments, one or more of: a colour (e.g. a CCT); Melanopic lux/ratio; intensity, are user adjustable for one or more of: the first time range; second time range; third time range; other time range. By implementing user control (e.g. an end user as opposed to a manufacturer) of one or more parameters of the output light, the device may provide improved realism/user customisation. Said parameters may be adjustable as fixed variables within a time range or to have a variable profile within a time range.

In embodiments, user adjustability is implemented by an input unit.

[Light sources]

In embodiments, the light sources (e.g. the channels) are independently controllable to produce colour to follow a curve in a chromaticity diagram that is representative of a daylight loci/spectrum, e.g. in a chromaticity space/colour space.

By implementing the light sources (e.g. at least three independently controlled light sources, which may comprise a blue, green or yellow and one or more white light emitting diodes) to emit an overall colour that is plotted along a line that flows, in a chromaticity diagram (or a colour space or other space), the daylight locus at various times of the day and/or conditions may be recreated by the device. With such an arrangement combined with a device at creates an impression of a sky scene at distant/infinite depth, a high degree of realism may be provided.

As used herein the term “day light locus” may refer to a graphical representation of the colour of daylight at various times and/or under different sky conditions. The daylight locus may be depicted on a chromaticity diagram, such as the CIE 1931 xy chromaticity diagram or other colour space or space. This diagram shows the range of colours that can be perceived by the human eye. The daylight locus represents the colours of daylight under different conditions, accounting for variations in colour temperature and spectral distribution. The term “representative of a daylight locus” may refer to an exact following of the daylight locus curve, or an approximation thereof, for example, a following of a black body/Planckian curve for warm CCT and the daylight locus for cold CCT, other examples include he TM 30 curve cam02/ucs.

As used herein the term “chromaticity diagram” may refer to a graphical representation of colours which may not consider brightness or intensity. Examples of which include CIE 1931 xy and CIE 1976 u'v'.

In embodiments, the electrical circuitry is configured to control the light source to produce colour to follow said daylight locus curve comprising a blackbody curve/Planckian locus. In embodiments, the daylight locus curve is followed, such that the colour produced is only on said curve.

In embodiments, the electrical circuitry is configured to independently control an intensity of the light sources (e.g. for at lest three independently controlled light sources, which may comprise a blue, green or yellow and one or more white light emitting diodes, including arranged as channels) and to produce colour to follow said curve. By enabling the intensity (e.g. in lumen/lux) of each of the different coloured light sources to be control, an overall colour of the output light may be tuned to remain on said curve.

In embodiments, the electrical circuitry is configured to control the light sources (e.g. the channels) to produce said colour to follow said curve for a plurality of different intensities. With such an implementation, for a given colour on said curve, a plurality of different overall intensities may be provided.

In embodiments, the electrical circuitry is configured to control the colour (e.g. by the channels) of the output light/diffuse light component to be within a MacAdam ellipse in a chromaticity diagram of a target position on said curve. By controlling the overall colour of the output light to be within 1 - 3 or 1 - 2 MacAdam ellipse of a target point on the daylight locus curve, a user may perceive precise daylight locus colour.

In embodiments, a CCT of the first white light source is 2 to 4 or 1 .5 to 5 times different to a CCT of the second white light source. Such a range may provide a high CRI/degree of controllability on the curve. In embodiments, the light source is controlled to provide output light with a colour rendering index (CRI) of at least 80, 85 or 90. By implementing the output light to have such a CRI range, including for all points on the daylight locus curve, a high degree of realism may be achieved, and may be particular important for high CCT.

In embodiments, the light source sources are arranged as a repeating unit, which repeats a plurality of times. By arranging the sources (e.g. at lest three light sources, which may comprise a blue, green and one or more white light emitting diodes) in a pattern that repeats in a regular manner, a high degree of uniformity of the diffuse skylight component may be achieved. In embodiments, a plurality of repeating units are arranged on a common substrate (e.g. a PCB or like board). In embodiments, the repeating unit repeats along at least one edge (e.g. along opposed edges) of a waveguide of the diffuse light generation system.

In embodiments, the electrical circuitry is arranged with independently controllable channels that comprise a plurality of the same colour light sources. By arranging the light sources of the repeating units into channels of the same colour (e.g. channels 1 - 4 for respective first white, second white, green, and blue sources) the intensity of the associated colours may be independently controllable. The individual channels may be arranged as parallel connected branches of a plurality of light sources in series (e.g. 4 - 15). In embodiments, an intensity of the light sources is controlled by pulse width modulation of the electrical current to the channels. For example, the PWM may be to provide an averaged constant current.

In embodiments, the electrical circuitry includes electronic memory storing calibration values that relate an intensity of the channels to a colour of the output light at preset positions along said curve and/or an overall intensity of the output light. By implementing a lookup table for intensity of the channels for a specific colour on the daylight locus, the device can be conveniently controlled to provide output light on the daylight locus. The calibration values may provide for each point on the curve, a plurality of different intensities, such that the same colour can be provide for a range of intensities. In embodiments, the electrical circuitry is configured to interpolate positions on said curve between the present positions based on the calibration values.

In embodiments, the diffuse light generation system includes the waveguide to receive light from the light source, and the redirecting features to redirect the diffuse sky light component from the waveguide, wherein the diffuse light generation system incudes a mixing region for mixing of the light of the light source prior to it encountering a redirecting feature. By implementing a mixing region to mix light/allow the light to settle before it is redirected, homogeneity of the diffuse sky light component in the output light may be improved over the output aperture.

In embodiments, the mixing region is formed as a peripheral region of the waveguide, with a central region of the waveguide comprising the redirecting features, with the central region of the waveguide to overlap the output aperture and the mixing region not to overlap the output aperture.

By implementing the mixing region as an outer portion of the waveguide, which is absent the redirecting features, and which does not overlap the output aperture (e.g. when viewed normal to a plane defined by a longitudinal and lateral direction), the mixing region may be conveniently integrated in the device. Moreover, it may enable the light source to be coupled to a side of the waveguide, at said mixing region, such that the light source is set back with reduced visibility to an observer gazing though the output aperture. In embodiments, the central region of the waveguide corresponds in shape to the output aperture.

In embodiments, the redirecting features increase in size (e.g. in one or more of depth; surface area, length scale, including radii) and/or number with respect to distance from the light source, e.g. for a center of the central region relative a periphery. By increasing a presence of the redirecting features from a periphery to a center of the central region, homogeneity of the diffuse skylight component may be improved, since a degree of uncoupling increases with distance from source.

[Use]

The present disclosure provides use of a diffuse light generation system of an output light generation system for an optical display device to create a perception of a sky scene with infinite depth in output light, wherein the diffuse light generation system comprises the features of any preceding embodiment or another embodiment disclosed herein.

[Method of assembly]

The present disclosure provides a method of assembling an optical display device arranged to create a perception of a sky scene in output light, the method may implement the features of any preceding embodiment, or another embodiment disclosed herein.

[Method of generating sky scene] The present disclosure provides a method of generating a perception of a sky scene in output light (e.g., through a perception of an aperture in a building). The sky scene may have infinite depth. The method may implement the features of any preceding embodiment, or another embodiment disclosed herein.

In embodiments, the method comprises controlling output light of the output light generation system (e.g. of one or more optical display devices, and optional room lighting) to output one or more of: a first distinct melanopic lux range at a first day time range, which is at least 200 melanopic lux; a second distinct melonic lux range at a second afternoon/evening time range, which not more than 50 melanopic lux, and; a third distinct melanopic lux range at a third night time range, which is not more than 1 melanopic lux.

In embodiments, the method comprises projecting the output light from: a first white light emitting diode to emit a first colour point; a green light emitting diode a to emit a second colour point; a blue light emitting diode to emit a third colour point, and; a second white light emitting diode to emit a fourth colour point, which is different to the first colour point. In embodiments, the method comprises controlling independently light emitting diodes to produce colour to follow a curve in a chromaticity diagram that comprises a daylight locus.

In embodiments, the method comprises: determining an overall intensity of the output light with an optical sensor system and/or colour, and; controlling output light of the output light generation system to produce a predetermined intensity and/or colour (e.g. a target point on said curve/a target intensity).

In embodiments, the method comprises: determining calibration values for the light emitting diodes and saving said calibration values to an electronic memory, wherein said calibration parameters relate an intensity of the light source units to a colour of the output light at preset positions along said curve and/or an overall intensity of the output light.

In embodiments, the method comprises projecting the output light through a transparent member.

The preceding summary is provided for purposes of summarizing some embodiments to provide a basic understanding of aspects of the subject matter described herein. Accordingly, the abovedescribed features are merely examples and should not be construed to narrow the scope or spirit of the subject matter described herein in any way. Moreover, the above and/or proceeding embodiments may be combined in any suitable combination to provide further embodiments. Other features, aspects, and advantages of the subject matter described herein will become apparent from the following Detailed Description of Embodiments, Figures, and Claims.

BRIEF DESCRIPTION OF FIGURES

Aspects, features and advantages of embodiments of the present disclosure will become apparent from the following description of embodiments in reference to the appended drawings in which like numerals denote like elements.

Figure 1 is a block system diagram showing an embodiment system for creating an artificial sky scene.

Figures 2 and 3 are block system diagrams showing embodiment optical display devices for creating an artificial sky scene of the system of figure 1 .

Figure 4 is an illustrative diagram showing the embodiment optical display device of figure 3.

Figures 5 is a block system diagram showing an embodiment optical display device for creating an artificial sky scene of the system of figure 1 .

Figure 6 is an illustrative diagram showing the embodiment optical display device of figure 5.

Figure 7 is an illustrative side view showing an embodiment light source of the optical display device of figure 3.

Figure 8 is an illustrative side view showing an embodiment light source of the device of figure 3.

Figure 9 is an illustrative plan view showing an embodiment waveguide and light source of the device of figure 3.

Figure 10 is an illustrative plan view showing an embodiment waveguide of the device of figure 3.

Figure 1 1 is a graphical illustration showing a chromaticity diagram for a skylight component of the device of figure 3.

Figure 12 is a graphical illustration showing CCT vs Melanopic ratio for a skylight component of the device of figure 3.

Figure 13 is an illustrative diagram showing an embodiment arrangement for measuring a distant depth of feature of an optical display device. DETAILED DESCRIPTION OF EMBODIMENTS

Before describing several embodiments of the device, it is to be understood that the device is not limited to the details of construction or process steps set forth in the following description. It will be apparent to those skilled in the art having the benefit of the present disclosure that the device is capable of other embodiments and of being practiced or being carried out in various ways.

The present disclosure may be better understood in view of the following explanations:

As used herein the term “optical display device” or “device” may refer to one or a plurality of electrically operated optical apparatus that is capable of providing an observer with a perception of a real-life sky when gazing into an output aperture of the device. The device creates a virtual sky scene. The virtual sky scene may have a perception of infinite depth (as for a real-life sky). The device may be dimensioned such that it is suitable for attachment to a ceiling or wall (e.g. a side wall, including a window) of an interior or a building, e.g., it is less than 1 .5 meters or 2 meters or 3 meters in lateral and/or longitudinal dimension; it may be greater than 0.20 meters in lateral and/or longitudinal dimension; it may have a depth of less than 0.5 meters. The output aperture may extend over a substantial amount of the lateral and/or longitudinal dimension of the device, e.g. within a frame that frames the output aperture that has a peripheral width of 0.5 - 5 cm in said lateral and/or longitudinal dimension. The device may include a mounting structure, e.g. brackets for mechanical fixings, for mounting to said ceiling or wall.

The device may recreate characteristics of said real-life sky. As used herein, the term “characteristics of a real-life sky” may refer to any optical characteristic of the real-life sky that is capable of measurement and replication in output light from the optical display device. A characteristic may include one or more of the following: a real-life colour of a real-life sky light component; a real-life colour of a real-life sun light component; a real-life intensity of a real-life sky light component; a real-life intensity of a real life sun light component, and; an angle of the real life sun light component. As used herein, the term “intensity” may refer to any quantity related to a brightness perceived by a user, e.g., one or more of a: radiant intensity, measured in watts per steradian (W/sr); luminous intensity, a measured in lumens per steradian (Im/sr), or candela (cd); Irradiance; luminous power, or luminous flux) measured in lumen. As used herein, the term “colour” may refer to a colour measured by a suitable colour system which may enable digital representation, e.g., colour correlated temperature (CCT) or a colour space, including RGB, sRGB, a Pantone collection, Cl ELAB or CIEXYZ etc. As used herein, the term “real-life colour” may refer to a colour as measured by a colour system, which is assigned, e.g., as an average or other numerical approximation, to an object. The object can be the sun or the sky. Said colour of the object may be measured without interference (including substantial interference) from other objects in the sky scene.

As used herein the term “real-life sky” may refer to a sky view that an observer observes when gazing through a window (e.g., in a side wall or ceiling) of a structure or otherwise from the ground. The portion of the sky view observed typically comprises the sun and surrounding sky, but in some cases, it may only comprise only the former or the latter. Hence a real-life sky may include a real-life sky light component and/or may include a real-life sun light component. The real-life sun light component may include a circular (including substantially circular) yellow/white sun (e.g., a warm colour) and includes direct light. The real-life sky light component includes indirect light from the sun and is absent the real-life sun light component. The real-life sky light component may include: a clear sky component, e.g., a blue/cold colour, and/or; cloud component e.g., a white/grey colour. The clear sky component may surround (including partially or fully) the circular sun. The cloud component can surround and extend over (including partially or fully) the sun.

As used herein “warm” in respect of the sun light component may refer to a yellow and/or white colour. The CCT may be 3000 - 5000k. As used herein “cold” in respect of the sky light component may refer to a blue and/or white colour. The CCT may be 5000 - 10000K.

As used herein the term “perception of infinite depth” may refer to a depth of an object (e.g., the sky and/or sun) in three dimensions being perceived as infinitely far away from an observer with stereopsis (e.g., binocular vision). A perception of infinite depth may be provided by one or more of: binocular convergence; motion parallax, and; accommodation visual depth perception cues, e.g., no conflict exists between these visual perception cues. The condition of infinite depth may be determined based on gaze vectors of the eyes of an observer with normal vision having the same and/or a similar alignment when looking into the device as for looking at the sky and/or sun in the real-life sky. The condition of infinite depth based on motion parallax may be determined based on the image of the sun appearing to be projected from the same location, e.g., moving, as an observer moves laterally and/or longitudinally across the output aperture. An observer user may maintain the same gaze vector associated with infinite depth during said motion.

As used herein the term “distant depth” may refer to a condition of infinite depth or other substantially far field depth, e.g. at least 5 or 10 or 20 or 50 or 100 metres in a depth direction from the output aperture. It may be defined by gaze vectors as mentioned previously of an observer gazing (e.g. from both their eyes, with normal vision) into the output aperture converging to a depth distance beyond the device, e.g. to one of said distance ranges discussed above.

As used herein the term “sky scene” or “virtual sky scene” may refer to a scene comprising a virtual representation that an observer observes when gazing through the output aperture of the optical display device. A sky scene may include a virtual sky light component and/or may include a virtual sun light component as defined herein. The sky scene may include a circular (including substantially circular) sun coloured image of the sun light component. The sun may be surrounded (including partially or fully) and/or overlapped (including partially or fully) by the sky light component. Alternatively, the sky scene may include the sky light component and no sunlight component.

As used herein the term “perception of a sky scene” may refer an observer perceiving a sky scene as being present in the real world, based on the construction by the device of a virtual sky scene that is sufficiently representative, e.g., in terms of chromatic and spatial distribution of light, to present as in the real-life sky.

As used herein the term “artificial sky light component” or “diffuse light component” may refer to artificial light that is representative of the real-life sky light component (e.g., absent the real-life sun light component), which can include a clear sky component and/or a cloud component (where both components are present the average component may be used) during daylight, sunset or sunrise. It may be representative of the real-life sky light component in respect of one or more of: colour, e.g., as defined by a CCT (e.g., 5000 - 10000K), the colour may only be blue or optionally white, e.g. to exclude sunrise/sunset conditions; diffusivity; luminance profile or intensity; other suitable parameter, and; a variance of any of the aforesaid over an output aperture of the device. The diffuse light component may be uniform such that is does not vary by more than 10% or 20% or 30% or 40% over the entire output aperture, e.g., in terms of one or more of: colour; luminance (e.g. in candelas per square meter (cd/m²), including luminance profile); intensity, and other suitable parameter. More particularly, said one or more parameters may be uniform to the extent where they do not vary by more than 10% or 20% or 30% or 40% for any given circular area on the output aperture of 10 mm diameter over at least 90% of the output aperture. In a particular example, the diffuse light is propagated over a HWHM solid angle that is at least 4 times larger or 9 times larger or 16 times larger than for the subtending HWHM solid angle of the sun light measured in Sr. The artificial sky light component may have a lumen of 3000 - 10.000, or 4000 - 7000. The diffuse sky light component in the output light may have a Lambertian distribution. A Lambertian distribution may refer to a type of diffuse reflection or scattering of light from a surface. The Lambertian model assumes that a surface reflects light uniformly in all directions. This means that the intensity of the reflected light is proportional to the cosine of the angle between the incoming light direction and the surface normal.

As used herein the term “sun light component” or “direct light component” may refer to artificial light that is representative of the real-life sun light component. It may be representative of the real-life sun light component in respect of one or more of: colour, e.g. as defined by a CCT (e.g. 3000 - 5000k, which is less than that of the sky light component); divergence (e.g. an angle of divergence of the light rays may be no more than 5 or 2 or 1 or 0.5 degrees relative each other); luminance profile or intensity; other suitable parameter, and; a variance of any of the aforesaid over an output aperture of the device. In a particular example, the luminance profile of the sun light may have a narrow peak in the angular distribution around the direction of propagation which is subtended by a HWHM solid angle smaller than 0.2 sr or 0.3 sr. The sun light component may be projected uniformly over the output aperture, e.g., such that an average direction of propagation within a circle of diameter 10 mm at any position over the output aperture does not vary in angle by more than 2 or 5 or 10%. The sun light component may present to a user when looking into the device, as a circular disc positioned at infinity. As used herein the term “collimated light” may refer to light that has been processed by a collimated light generation system, which may form the sun light component.

As used herein the term “output aperture” may refer to a viewing window of the device into which an observer can gaze. The output aperture may be 0.3 - 2 m x 0.3 - 2 m. The output aperture outputs the output light which is generated by the device. The output aperture may include a transparent member or a void instead of such a member. The output aperture may include a frame that frames the transparent member. As used herein the term “transparent member” may refer to a medium through which the output light is projected. The transparent member may be planar. The transparent member may be formed of glass or plastic or other suitable material.

As used herein the term “reflective member” may refer to an object that is capable of reflecting an image by specular reflection. It can include a member with any surface in which the texture or roughness of the surface is smaller (smoother) than the wavelength of the incident light. It may include surfaces formed of one or more of the following reflective materials: metals; metal oxides, and; dielectric materials. Examples of which include silver, aluminium, a titanium oxide based material including titanium dioxide or titanium trioxide. Any of the aforementioned may be applied as a thin coating on a glass carrier.

As used herein the term “a reflective and partially transmissive member” or “partially reflective member” may refer to a reflective member as defined above, which is additionally configured to transmit therethrough a portion of light which is not reflected. An example of which is a member formed with a lesser thickness than for the aforedescribed reflective material. The transmissivity maybe less than 50% or 30% for incident electromagnetic radiation. The thickness of the reflective material may be any one or the following: less than 700 nm; less than 100 nm; less than 50 nm, and; less than 5 nm, with any of the aforementioned maximum thickness ranges implemented with a minimum thickness of 1 nm.

As used herein the term “output light generation system” may refer to a single (or a distributed system) capable of generating the output light. The output light generation system maybe implemented as a diffuse light generation system and/or a collimated light generation system. The output light generation system may generate all the output light, or part of the output light. For example, output light may also include a portion of light down stream of the output aperture (e.g. other lighting in a room where said device is installed) which is transmitted into the device, via the output aperture, reflected and projected back out.

As used herein the term “diffuse light generation” or “diffuse light generation system” may refer to a single or a distributed system capable of generating the diffuse light component, e.g., light which is scattered at many angles as opposed to one angle as with specular reflection/collimated light. The diffuse light generation may generate the diffuse light component by redirecting/scattering light that is incident/encounters uncoupling/redirecting features. The light may be supplied by a dedicated light source. The diffuse light generation may be at least partially transparent and may at least partially generate the diffuse light component from the light transmitted therethrough (which can include light from the collimated light generation system). The uncoupling features/redi recti ng features may be implemented as one or more of the following: particles to scatter light; conical micro cones; micro lenses; quantum dots; surface features, including surface etching, and; other suitable implementations. As used herein the term “scattering light” may refer to a process performed on light by the diffuse light generation to generate diffuse light, any may include Rayleigh scattering. As used herein the term “particles to scatter light” may refer to particles with a diameter selected to scatter some or all wavelengths of visible light. The diameter of the particles may be micro or nano (e.g., to operate in the Rayleigh regime). The diffuse light generation can include said particles arranged in a medium, e.g., as a waveguide. Examples include titanium dioxide suspended in PMMA. As used herein the term “light guide panel” or “waveguide” may refer to a generally planar member, which is arranged to convey light in an in-plane direction, e.g., by total internal reflection. The waveguide may be edge lit or otherwise lit by a light source. The waveguide may be implemented as the diffuse light generation, e.g., with a diffuse light component to exit the waveguide upon encountering an uncoupling/redirecting feature.

As used herein the term “light source” may refer to any arrangement capable of generating artificial light. It can include arrangements that transform electrical current into a light emission, e.g. as luminous radiation. The light may have wavelengths in the range of 400-700 nm. The light source can include one or more of the following: a white light source, or perceived as such by the eye, e.g., an incandescent lamp, a fluorescent lamp, a mercury vapor discharge lamp; an LED or a white light laser diode (that is, such that the primary source is combined with a phosphor or several phosphors) or a combination of LEDs or laser diodes of different colour, and; other suitable light source. The light source may include a light guide panel to receive light from an emitting portion and convey the light, e.g., by total internal reflection, to an output surface. The light source may be arranged to emit with a CCT of 3K to 20K, or over a daylight locus. The luminance profile may not vary by more than 20% over any circular area of 10 mm diameter. The light source may include a light guide to guide the light to the output light generation system or the other components of the output light generation system.

As used herein the term “chromatic system” may refer to an arrangement capable of imparting a particular colour to light, e.g., from the light source. The colour may be representative of the real-life colour of sky/sun light component, including daylight, sunset or sunrise. It may for example include a filter.

As used herein the term “collimated light generation system” may refer to a system for processing light from a light source to the collimated light. It may include one or more of the following collimating systems: a lens, including a Fresnel lens; a parabolic reflector; a closed cell structure, through the cells of which light is projected, and; other suitable system. The collimated light generation system may include a light source.

As used herein, the term “prism sheet” or may refer to an arrangement of prisms on a planar member, which maintain an initial degree of collimation of an incident light beam, but which expands said beam. The expansion may be achieved by reflection or reflection and/or refraction. An example of such an arrangement is disclosed in WO2017048569A.

As used herein, the term "electrical circuitry" or "circuitry" or "control electrical circuitry" may refer to one or more hardware and/or software components, examples of which may include: one or more of an Application Specific Integrated Circuit (ASIC) or other programable logic; electron ic/electrical componentry (which may include combinations of transistors, resistors, capacitors, inductors etc); one or more processors (e.g. circuitry structure of the processor); a non-transitory memory (e.g. implemented by one or more memory devices), that may store one or more software or firmware programs; a combinational logic circuit; interconnection of the aforesaid. The electrical circuitry may be located entirely at one component of the system, or distributed between a plurality of components of the system (e.g. a server system and/or external device) which are in communication with each other over a computer network via communication resources.

As used herein, the term "computer readable medium/media" or "data storage" may include any medium capable of storing a computer program, and may take the form of any conventional non-transitory memory, for example one or more of: random access memory (RAM); a CD; a hard drive; a solid state drive; a memory card; a DVD. The memory may have various arrangements corresponding to those discussed for the circuitry.

As used herein, the term "processor" or "processing resource" may refer to one or more units for processing, examples of which include an ASIC, microcontroller, FPGA, microprocessor, digital signal processor (DSP), state machine or other suitable component. A processor may be configured to execute a computer program, e.g. which may take the form of machine readable instructions, which may be stored on a non-transitory memory and/or programmable logic. The processor may have various arrangements corresponding to those discussed for the circuitry, e.g. on-board or distributed as part of the system. As used herein, any machine executable instructions, or computer readable media, may be configured to cause a disclosed method to be carried out, e.g. by the system or components thereof as disclosed herein, and may therefore be used synonymously with the term method, or each other.

As used herein, the term "communication resources" or "communication interface" may refer to hardware and/or firmware for electronic information transfer. The communication resources/interface may be configured for wired communication (“wired communication resources/interface”) or wireless communication (“wireless communication resources/interface”). Wireless communication resources may include hardware to transmit and receive signals by radio and may include various protocol implementations e.g. the 802.11 standard described in the Institute of Electronics Engineers (IEEE) and Bluetooth™ from the Bluetooth Special Interest Group of Kirkland Wash. Wired communication resources may include; Universal Serial Bus (USB); Ethernet, DMX, or other protocol implementations. The device may include communication resources for wired or wireless communication with an external device and/or server system.

As used herein, the term "network" or "computer network" may refer to a system for electronic information transfer between a plurality of apparatuses/devices. The network may, for example, include one or more networks of any type, which may include: a Public Land Mobile Network (PLMN); a telephone network (e.g. a Public Switched Telephone Network (PSTN) and/or a wireless network); a local area network (LAN); a metropolitan area network (MAN); a wide area network (WAN); an Internet Protocol Multimedia Subsystem (IMS) network; a private network; the Internet; an intranet; personal area networks (PANs), including with Bluetooth a short-range wireless technology standard.

As used herein, the term “external device” or "external electronic device" or “peripheral device” may include electronic components external to one or more of: the device, and; the server system, e.g. arranged at a same location or remote therefrom, which communicate therewith over a computer network. The external device may comprise a communication interface for electronic communication. The external device may comprise devices including: a smartphone; a PDA; a video game controller; a tablet; a laptop; or other like device.

As used herein the term “database” may refer to a data storage configuration which may be implemented as a key-value paradigm, in which an electronic record as a key and is associated with a value.

As used herein, the term “server system” may refer to electronic components external to one or more of: the device, and; the external device, e.g. arranged at a same location or remote therefrom, which communicate therewith over a computer network. The server system may comprise a communication interface for electronic communication. The server system can include: a networked-based computer (e.g., a remote server); a cloud-based computer; any other server system.

As used herein, the term “transparent member mounting system” may refer to an arrangement configured to mount the transparent member to a frame of the device. The mounting system may implement a support structure and a fixing system(s), to secure the support structure to the frame and/or transparent member. The support structure may implement a support portion and/or a gasket portion. As used herein, the term “support portion” may refer to a portion of the support structure that supports the transparent member. As used herein, the term “gasket portion” may refer to a portion of the support structure that provides an appearance of least one gasket. The gasket portion and support portion may be separate portion or overlapping. As used herein, the term “appearance of at least one gasket” may refer to an impression of a real-life gasket of a window being presented to a user, e.g., a thin rim which may have a black or dark grey colour.

As used herein, the term “spacer” or “edge member” may refer to a member that creates an appearance of a seal that seals over a side face of a glass member of a window, including between sheets of glass/a cavity therebetween. As used herein, the term “appearance of a seal” may refer to an impression of a real-life seal of a window being presented to a user, e.g., viewed from downstream of the output aperture. The spacer may have a metallic appearance, e.g., grey and reflective, to recreate and appearance of an aluminium spacer. The spacer may be formed from a flexible membrane, e.g., a tape. The surface finish of the spacer may be different to that of the frame, e.g., so that it may be clearly identified as a spacer.

As used herein the term “reflector arrangement” may refer to an arrangement/configuring of components to provide a reflected image, e.g., a ghost image, as is observed when a user looks into a real-life window, particularly at night. The image may appear in the output aperture, e.g., when a user gazes into the device. The image may be of a feature of the device or a room in which the device is installed, e.g., a light source that is present in the room and not the device. In some examples the image comprises a first and a second image, e.g., a double reflection of the same image.

As used herein the term “virtual image” or “image” may refer to a reflection of a feature that is present in the output light in addition to the actual feature, but at a different position.

As used herein, the term “providing an appearance in output light” or like term, may refer to photons of light being perturbed e.g., spatially and/or chromatically by an item/feature of the optical device and made visible to a user by their projection/conveying to an eye of a user when gazing into the output aperture of the optical display device.

As used herein, the term “viewed from downstream of the output aperture” may refer to any and/or all viewing positions that are achievable by a user from downstream (e.g., from a side of a transparent member of the output aperture comprising an exterior face) the output aperture. Said position may include downstream of the frame since the frame forms the output aperture, and may preclude a viewing position within the bounds of the frame.

As used herein, the term “virtual transparent member” or “glass member of a window” may refer to an arrangement that provides an appearance in the output light of an actual glass member of a window (e.g., as an image observed in the output aperture), which may be different to the appearance of the actual transparent member, which is present in the device. The glass member of a window that is observed virtually may comprise two or more sheets of glass separated by cavities(s), with a spacer therebetween.

As used herein the term “trim portion” may refer to a portion of the frame that is removable from a body of the frame to provide a different finish for a visible portion of the frame, which maybe visible when viewed from downstream of the output aperture and/or access to control electronics.

[General system description]

Referring to figure 1 , the system 2 comprises: devices 4 for output of output light 6, and electrical circuitry 8 for control of various characteristics of the output light 6, as will be discussed. The electrical circuitry 8 may be distributed on one or more of: one or more of the devices 4; a server system (not illustrated); an external device (not illustrated).

In variant embodiments, which are not illustrated: the system comprises a single or other number of devices, in the instance of multiple devices, said devices can be arranged in series with each other as a combinatory assembly; each device comprises its own dedicated electrical circuitry rather than the electrical circuitry controlling multiple devices.

Herein, the device 4 may refer to one or a plurality of like devices, which may me arranged next to each other when mounted to a ceiling or wall.

Referring to figure 2, a general device 4 comprises: an output light generation system 10 for generation of the output light 6; an output aperture 12 for of the output light 6, and the electrical circuitry 8 for control of the output light generation system 10. The output light 6 is generally projected in the depth directed 104, which is orthogonal to the plane of the output aperture 12. [First example]

Referring to figure 3 a first device example of the device 2, which incorporates features and associated variants of the aforedescribed general device 2, comprises the output light generation system 10 arranged as a diffuse light generation system 14. In the first example, the output light generation system 10 does not comprise a collimated light generation system, hence the output light 6 includes only a sky light component 16.

Referring to figure 4, in further detail the first example comprises the diffuse light generation system 14 arranged with a waveguide 18 and a light source 20. The output aperture 12 comprises a transparent member 22 and is defined by a frame 24. The device 2 includes a housing 26 to house said components.

The output aperture 12 is planar and is aligned in the longitudinal direction 100 and lateral direction 102. A thickness of the device 4 is arranged in the depth direction 104.

The frame 26 surrounds the transparent member 22 and gives an impression of a real-life window or skylight frame.

The light source 20 emits light in the longitudinal direction 100 into a side face of the waveguide 18. The waveguide 18 includes redirecting features (not illustrated) though its section which scatter the internally reflected light from the light source 20. The light emitted from the light source 20 is retained within the waveguide 18 by total internal reflection until it encounters a redirecting features and is scattered enabling it to exit the waveguide 18 as the diffuse sky light component 18.

In variant embodiments, which are not illustrated: the diffuse light generation system is alternatively configured; uncoupling features are on an edge of the waveguide, which are configured to decouple the light therefrom; the diffuse light generation system comprises a backlit rather than an edge lit arrangement.

The transparent member 22 includes an interior face 36 that faces into the device 2, and into the output light generation system 10 and an exterior face 38 that faces away from the device 2 (which an observer gazes directly into) and a side face 40 extends between the interior face 36 and the exterior face 38 and around a periphery of the interior face 36 exterior face 38. The transparent member 22 is aligned in the longitudinal direction 100 and lateral direction 102. The frame 24 includes: an interior side face 42; an outer side face 44; a top face 46, and; a bottom face 48. The top face 46 is arranged at a greater depth in the depth direction 104 than the bottom face 48.

[Second example]

Referring to figures 5 and 6 a second device example includes the features of the first example and associated variants, but with the output light generation system 10 additionally implementing a collimated light generation system 28 to generate a sun light component 30.

The collimated light generation system 28 includes a light source 32 and a collimating system 34. The light source 32 projects a light beam (not illustrated) to the collimating system 34, which processes the received light beam to output collimated light which subsequently becomes the sun light component 30.

The light source 32 is implemented as a 2-dimmensional array of LEDs, which can be arranged on a common substrate (not illustrated) that extends in the lateral direction 100 and the longitudinal direction 102. The collimating system 34 is implemented as a 2-dimmensional array of lenses (not illustrated), each of which being associated with an LED. A homogenising element (not illustrated) may optionally be implemented subsequent to the collimating system 34 to remove stray light which may be introduced by the collimating system 34 and/or the light source 32, e.g. as an absorbent honeycomb through which the collimated light passes.

In variant embodiments, the collimated light generation system is alternatively implemented, including: as a single or 1 -dimensional array of light sources, which are expanded over the output aperture, e.g. by using an expansion system, which can include one or more reflective members and prism sheets, and; the collimating system is alternatively implemented as parabolic reflectors or other collimating systems; the collimated light generation system is implemented as a laser light source, which may obviate the collimating system. The collimated light generation system may also be separate from the diffuse light generation system, e.g., as a spotlight.

[Light source configuration and arrangement]

Referring to figure 7, in a first light source example, the optical display device 4, which may implement the features of any preceding embodiment (e.g. the first or second device example), is arranged with the light source 20 of the diffuse light generation system 14 of the output light generation system 10, to comprise: 1 ) a first white light emitting diode 50 to emit a first colour point;

2) a green light emitting diode 52 a to emit a second colour point, and;

3) a blue light emitting diode 54 to emit a third colour point.

The first to third colour points are different. The colour point is a coordinate on a 1931 CIE Chromaticity Diagram, however other colour systems/chromaticity diagrams may be implemented.

The white light emitting diode is configured to emit light with a CCT of 1400k - 10000k or 1400k - 4000k. The wave band can be 380 - 750 nm. The white light emitting diode can be implemented by an RGB configuration or by a phosphor converted blue light emitting diode, or other suitable arrangement.

The green light emitting diode is configured to emit light with a wave band of 520 nm to 565 nm, both range extremities may be ± 5 % or ± 10 %.

The blue light emitting diode is configured to emit light with a wave band of 450 to 495 nm, both range extremities may be ± 5 % or ± 10 %.

The light emitting diodes 50 - 54 are arranged as a repeating unit 56, which is linear and repeats in a linear manner along opposed edges of the waveguide 18 (as will be discussed). The light emitting diodes 50 - 54 are arranged on a substrate 60 such as a printed circuit board (PCB). The substrate 60 may carry one or more repeating units 56.

The repeating unit 56 is repeated a plurality of times e.g. at least 10 or 20. Adjoining light emitting diodes of the repeating unit 56 are arranged with minimum separation, as are adjoining repeating units 56. In this way, a high degree of uniformity of colour of the diffuse skylight component may be achieved.

In variant embodiments, which are not illustrated: other colour combinations of light emitting diodes may be implemented, for example; an RGB, however it is preferable to avoid a red light emitting diode to achieve a high melanopic ratio and/or CRI as will be discussed; a yellow instead of a green light emitting diode; whilst the light emitting diodes are shown as arranged in a linear configuration, other configurations are to be complemented, e.g. side by side; whilst the light source is exemplified as comprising a plurality of repeating units, in other embodiments only one of said unit may be implemented. Referring to figure 8, in a second light source example the arrangement of the first light source example additionally comprises:

4) a white light emitting diode 58 to emit a fourth colour point.

In the second light source example: the first white light emitting diode 50 is configured to emit light with a CCT of 1800k, which may be ± 10 % or ± 20 % or ± 30 %, and; the second white light emitting diode 58 is configured to emit light with a CCT of 6500k, which may be ± 10 % or ± 20 % or ± 30 %. The other features of the second white light emitting diode 58 may be as for the first white light emitting diode 50.

The first to fourth colour points are different, and in particular, the fourth colour point is different to the fist colour point. By implement a second white light emitting diode with a different emission to the first light emitting diode a greater control of an overall colour point of the light source may be achieved including with a high melanopic ratio and/or CRI as will be discussed.

Referring to figures 9 and 10, in embodiments in which the diffuse light generation system 14 includes the waveguide 18 to receive light from the light source 20, the diffuse light generation system 14 incudes a mixing region 70 for mixing of the light prior to it encountering a redirecting feature 72.

The mixing region 70 is formed as a peripheral region of the waveguide 18 and includes the side face 86 on the opposed edges that the light source 20 is arranged. The mixing region may be 0.5 - 5 cm in the lateral dimension 102. The mixing region 70 is identifiable from other portions of the waveguide 18 since it does not comprise redirecting features 72 and does not overlap the output aperture 12. The mixing region 70 allows the light from the different light emitting diodes to mix and achieve a degree of uniformity/homogeneity before encountering a redirecting feature 72. In this way only light that has achieved said degree of uniformity may be decoupled from the waveguide and form part of the output light 6. Any non-uniform light may provide undesirable visual cues that the skylight component 16 is not perceived with infinite depth (as in a real life sky light). Moreover, said an arrangement enables the light source 20 to be coupled to a side of the waveguide 18, such that it is set back from the output aperture 12 (e.g. in the lateral 102 or longitudinal direction 100) which may help reduce the visibility of the light source to an observer gazing though the output aperture 12.

A central region 74 of the waveguide 18 adjoins the mixing region 70 and can be identified as: comprising the redirecting features 72; and/or to overlap the output aperture 12 (e.g. in the lateral 102 or longitudinal direction 100). Hence the central region 74 can correspond in shape to the output aperture 12.

In variant embodiments, which are not illustrated: the light source may be alternatively arranged, e.g. on any one or more edge of the waveguide; the mixing region may be omitted; the mixing region may be separately formed rather than integrating it with the waveguide.

Referring to figure 10, the redirecting features 72 are formed on the interior face 82 (as shown in figure 4) of the waveguide 18 and increase in size (herein diameter and depth) with the lateral direction 102 towards a center of the central region 74 relative both the peripheries where the light source 20 is located. By increasing a presence of the redirecting features from a periphery to a center of the central region 74, homogeneity of the diffuse skylight component may be improved, since a degree of uncoupling increases with distance from source to compensate for attenuation of the light.

In variant embodiments, which are not illustrated, the redirecting features can increase in size in terms of one or more of: depth; surface area, length scale, including radii, and; a number of redirecting features; the redirecting features may be distributed within the waveguide, rather than formed on a surface, however they may increase in size as disclosed for the surface formation embodiment; the redirecting features may be uniformly distributed; the redirecting features may be formed on the exterior face and/or interior face of the waveguide.

[Light source control]

In both the first light source example, and the second light source example (including their associated variants) the light emitting diodes 50, 52, 54, 58 are each independently controllable (relative to each other) by the previously discussed electrical circuitry 8 in terms of their intensity to control a colour and/or intensity of the diffuse sky light component 16 in the output light 8.

The control is implemented by pulse width modulation (PWM) of the electrical current to the light emitting diodes 50, 52, 54, 58, e.g. to provide a constant average current. In variant embodiments, other control may be implemented, e.g. voltage control and/or with a constant current.

In embodiments, in which there are a plurality of repeating units 56, the electrical circuitry 8 may be arranged with independently controllable channels that comprise a plurality of the same colour light sources. For example:

1 ) all first white light emitting diodes 50 may be arranged as a first channel; 2) all green light emitting diodes 52 may be arranged as a second channel;

3) all blue light emitting diodes 54 may be arranged as a third channel, and;

4) all second white light emitting diodes 58 may be arranged as a fourth channel.

In this way an intensity of the associated colour is independently controllable by channel, e.g. by pulse width modulation as previously described.

The individual channels may be arranged as parallel connected branches of a plurality of light sources in series. For example, each channel 1 - 4 may comprise one or more branches, whereby a branch comprises a plurality of light sources in series (e.g. 4 - 15). In variant embodiments, other connection configurations may be implemented, e.g. all in series or all in parallel etc.

In embodiments, the light sources 50, 52, 54, 58 (e.g. the channels) are independently controllable by the electrical circuitry 8 to produce colour of the diffuse sky light component 16 to follow a curve in a chromaticity diagram (e.g. a 1931 CIE Chromaticity Diagram), said curve may be representative of a daylight locus.

In an example, said curve comprises a combination of blackbody curve/Planckian locus for warm (lower CCT) that transitions to a daylight locus for cold (higher CCT). Said transition can be at a CCT of 4500 K to 5500 K ± 10%. By configuring the diffuse sky light component 16 to follow such a curve that resembles the daylight locus, daylight may be accurately be recreated at a range of times of the day. In variant embodiments, other curves may be implemented.

The colour of the diffuse sky light component 16 may be controlled to follow said curve such that the colour produced is only on said curve. More specifically, said control can be to be within 1 - 3 or 1 - 2 MacAdam ellipse in said chromaticity diagram of a target position on said curve. In this way a user may perceive precise daylight locus colour.

In embodiments, the electrical circuitry 8 is configured to independently control an intensity of the light sources 50, 52, 54, 58 (e.g. the channels) such that for each point on the curve, there are multiple intensities. In this way a user may adjust the intensity of the diffuse sky light component 16 whilst maintaining the same colour.

Such an arrangement may be implemented by a look up table that is stored on electronic memory of the electrical circuitry 8. The look up table comprises for each channel a calibration value associate with an intensity of the channel for a target intensity and colour of the diffuse sky light component 16 on the curve. In the example of PWM control, the calibration value can be the duty cycle. In other control implementations it may be other parameters, e.g. a voltage.

In embodiments, the electrical circuitry 8 is configured to interpolate positions on said curve between the preset positions based on the calibration values, e.g. by a known linear or polynomial interpolation technique.

The electrical circuitry 8 may also implement adaptation of the calibration values with hours of usage of the device, since as the light emitting diodes age, their intensity at a given power may decrease, hence the duty cycle may be increased. For example, once it is determined that a predetermined usage threshold has been met, the calibration values may be adapted (e.g. by means of a suitable mathematical function) or they may be substituted for a further set of calibration values, which may be stored electronic memory of the electrical circuitry 8 and/or downloaded via the server system or electronic device.

The electrical circuitry 8 may also implement a temperature-based control of the light source. For example, a temperature sensor (not illustrated) may be arranged on the PCB (or in operative proximity thereto) to enable a determination of whether a temperature has crossed a threshold, and if crossed a power of electrical energy to the light source may be controlled (e.g. limited) to prevent/reduce further temperature increase, e.g. by the duty cycle, which may limit an intensity of the diffuse skylight component.

In embodiments, the electrical circuitry 8 is configured to control the light source 20 to emit the diffuse sky light component 16 in the output light 10 to have a CCT of a maximum of at least 12,000 K or 15,000 K or 20,000 K or 30,000 K, which may be up to a maximum CCT of 500,000 K or 100,000 K or 60,000 K or 50,000 K or 45,000 K. A high CCT may implement due to the first white light emitting diode 50 and/or the second white light emitting diode 58. In embodiments, the electrical circuitry 8 is configured to control the light source 20 to emit the diffuse sky light component 16 in the output light 10 with a CCT of a minimum of 1000 K or 1500 K or 2000 K.

In embodiments, the electrical circuitry 8 is configured to control the light source 20 to emit the diffuse sky light component 16 in the output light 10 to have a colour rendering index (CRI) of at least 80, 85 or 90. [Melanopic lux control]

Referring to figure 11 , the optical display device 4, which may implement the features of any preceding embodiment, including the first or second light source example, is arranged with the electrical circuitry 8 to control the light source (e.g., the light source 20 of the diffuse light generation system 14 of the output light generation system 10, which may optionally include a collimated sunlight component), to implement in the output light 6 the illustrated light profile melanopic lux (EML) profile 120 and CCT profile 122.

The melanopic lux profile 120 includes: a first distinct melanopic lux range at a first day time range 124, which is greater than 180 or 200 or 250 melanopic lux; a second distinct melonic lux range at a second afternoon/evening time range 126, which is less than 50 or 60 melanopic lux, and; a third distinct melanopic lux range at a third night time range 128, which is less than 1 melanopic lux.

The CCT profile 122 appears warm (e.g. 2000 - 3000 K) initially in the morning 130 and in the evening 132 due to sunrise and sunset respective. At midday 134 the CCT is coolest (e.g. 5000K to 6500K, or more including one of the aforedescribed CCT ranges). In the night the CCT can be below 2000 K. The melanopic lux profile 120 and CCT profile 122 therefore mimic natural variations in color temperature to create specific atmospheres or enhance the circadian rhythm for indoor spaces.

In variant embodiments, which are not illustrated, the electrical circuitry 8 implements one or more other time ranges with a predetermined melanopic lux and CCT, e.g. a mid-afternoon or early morning. Increasing a number of time ranges may improve resolution/customisability of a light profile.

The start time and/or end time (e.g. including a duration) may be user adjustable for one or more of the: first time range; second time range; third time range; other time range.

In a similar manner, one or more of parameters comprising: a colour (e.g. a CCT); melanopic lux/ratio; intensity, may be user adjustable for one or more of: the first time range; second time range; third time range; other time range. Said parameters may be adjustable as fixed variables within a time range or to have a variable profile within a time range.

Said user adjustability may be implemented by a user interface (not illustrated), e.g. of the electrical circuitry 8 of the device 4 or of an external device (not illustrated) or a server system (not illustrated). For example, the time and parameter may be displayed by the user interface as nodes that can be selected and moved to change the graphical profile, e.g. as drag and drop functionality.

Referring to figure 12, the determined melanopic ratio of the diffuse sky light component 16 is shown as the dependent variable vs the CCT as the independent variable. Given that the COT of the diffuse skylight component 16 is high for the device 4 (in the graphical example with a peak of 40,000 K) the peak melanopic ratio peaks at a relatively high 1 .6. In variant embodiment, which are not illustrated, the melanopic ratio can have a maximum of at least 1.2 or 1.4 or 1.6, which may extend up to 2, 3, 4 or 6.

[Distant depth]

Referring to figure 13, the output light generation system is configured to generate a sky scene which is absent features (e.g. visual cues that an observer may focus on) 70 that appear to an observer gazing into the output aperture 12 to be at an apparent depth ZA a either within a depth ZD of the device 4 (e.g. at the output aperture 12), or within 5 - 10 or 20 times the depth ZD of the device 4.

ZA is determined by projecting line of sight vectors V1 , V2 from a first viewing position P1 and a second viewing position P2 through the output aperture 12 to a perceived location of the one or more features 70. ZA represents a distance from the output aperture 12 to a convergence point of these vectors beyond the physical depth ZD of the device.

It will be understood that the angles between the line of sight vectors V1 , V2 at the viewing positions P1 , P2 can be determined, e.g.: by eye tracking software in the event that human eyes are represented by P1 and P2; or by angles of cameras at P1 , P2, arranged to focus on the feature 70. The distance between P1 and P2 is known as is the distance from the output aperture 12. Hence trigonometric relationships can be used to calculate ZA.

As used in this specification, any formulation used of the style “at least one of A, B or C”, and the formulation “at least one of A, B and C” use a disjunctive “or” and a disjunctive “and” such that those formulations comprise any and all joint and several permutations of A, B, C, that is, A alone, B alone, C alone, A and B in any order, A and C in any order, B and C in any order and A, B, C in any order. There may be more or less than three features used in such formulations. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word ‘comprising’ does not exclude the presence of other elements or steps then those listed in a claim. Furthermore, the terms “a” or “an,” as used herein, are defined as one or more than one. Also, the use of introductory phrases such as “at least one” and “one or more” in the claims should not be construed to imply that the introduction of another claim element by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim element to inventions containing only one such element, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an." The same holds true for the use of definite articles. Unless stated otherwise, terms such as “first” and “second” are used to arbitrarily distinguish between the elements such terms describe. Thus, these terms are not necessarily intended to indicate temporal or other prioritization of such elements. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage.

Unless otherwise explicitly stated as incompatible, or the physics or otherwise of the embodiments, example or claims prevent such a combination, the features of the foregoing embodiments and examples, and of the following claims may be integrated together in any suitable arrangement, especially ones where there is a beneficial effect in doing so. This is not limited to only any specified benefit, and instead may arise from an “ex post facto” benefit. This is to say that the combination of features is not limited by the described forms, particularly the form (e.g. numbering) of the example(s), embodiment(s), or dependency of the claim(s). Moreover, this also applies to the phrase “in one embodiment”, “according to an embodiment” and the like, which are merely a stylistic form of wording and are not to be construed as limiting the following features to a separate embodiment to all other instances of the same or similar wording. This is to say, a reference to ‘an’, ‘one’ or ‘some’ embodiment(s) may be a reference to any one or more, and/or all embodiments, or combination(s) thereof, disclosed. Also, similarly, the reference to “the” embodiment may not be limited to the immediately preceding embodiment.

The foregoing description of one or more implementations provides illustration and description, but is not intended to be exhaustive or to limit the scope of the invention to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practice of various implementations of the present disclosure.

LIST OF REFERENCES

2 System Device(s)

6 Output light

10 Output light generation system

14 Diffuse light generation system

16 Sky light component

18 Waveguide

82 Interior face

72 Redirecting features

84 Exterior face

86 Side face

70 Mixing region

74 Central region

20 Light source

56 Repeating unit

50 First white light emitting diode

52 Green light emitting diode

54 Blue light emitting diode

56 Second white light emitting diode

60 PCB

28 Collimated light generation system

30 Sun light component

32 Light source

34 Collimating system

12 Output aperture

22 Transparent member

36 Interior face

38 Exterior face

40 Side face

24 Frame

42 Interior side face

44 Exterior side face

46 Top face

48 Bottom face

26 Housing

8 Electrical circuitry

Claims

1 . An optical display device arranged to create a perception of a sky scene, the optical display device comprising: an output aperture for output of output light; an output light generation system comprising a light source to generate output light and a diffuse light generation system to generate a diffuse sky light component from light from the light source, and; electrical circuitry to control the light source, wherein the electrical circuitry is configured to control the light source to emit output light with a CCT of a maximum of at least 12,000 K and a with a colour rendering index (CRI) of at least 80.

2. The optical display device of claim 1 , wherein the electrical circuitry is configured to control the light source to emit output light with at least two of: a first distinct melanopic lux range at a first day time range, which is at least 200 melanopic lux; a second distinct melonic lux range at a second afternoon/evening time range, which not more than 50 melanopic lux, and; a third distinct melanopic lux range at a third night time range, which is not more than 1 melanopic lux.

3. The optical display device of any preceding claim, wherein the light source comprises: a first white light source channel to emit a first colour point; a second coloured light source channel to emit a second colour point; a third coloured light source channel to emit a third colour point, which is different to the second colour point, wherein the light source is substantially absent a red light source.

4. The optical display device of claim 3, wherein the light source comprises: the second coloured light source channel as a green or yellow light source, and; the fourth coloured light source channel a blue light source.

5. The optical display device of either of claims 3 or 4, wherein the light source comprises: a second white light source channel to emit a fourth colour point, which is different to the first colour point.

6. The optical display device of claim 5, wherein a CCT of the second white light source channel is 1 .5 - 6 times that of the first white light source channel.

7. The optical display device of any of claims 3 to 6, wherein the electrical circuitry is configured to independently control the light source channels to produce colour to follow a curve in a chromaticity diagram that is representative of a daylight locus.

8. The optical display device of claim 7, wherein the electrical circuitry is configured to control the light source channels to produce said colour to follow said curve for a plurality of different intensities.

9. The optical display device of either of claims 7 or 8, wherein the electrical circuitry is configured to control the colour of the output light to be within a MacAdam ellipse in a chromaticity diagram of a target position on said curve.

10. The optical display device of any of claims 7 to 9, wherein the electrical circuitry includes electronic memory storing calibration values that relate an intensity of the channels to a colour of the output light at preset positions along said curve and/or an overall intensity of the output light.

1 1. The optical display device of claim 10, wherein the electrical circuitry is configured to interpolate positions on said curve between the present positions based on the calibration values.

12. The optical display device of any preceding claim wherein the light source sources are arranged as a repeating unit, which repeats a plurality of times, wherein the repeating unit repeats along at a substrate.

13. The optical display device of any of claims 3 to 12, wherein an intensity of the light source channels is controlled by pulse width modulation of the electrical current to the channels.

14. The optical display device of any preceding claim, wherein the diffuse light generation system includes a waveguide to receive light from the light source, and redirecting features to redirect the diffuse sky light component from the waveguide, the light source optically coupled to an edge of the waveguide.

15. The optical display device of claim 14, wherein the diffuse light generation system incudes a mixing region for mixing of the light of the light source prior to it encountering a redirecting member.

16. The optical display device of claim 15, wherein the mixing region is formed as a peripheral region of the waveguide, with a central region of the waveguide comprising the redirecting features, with the central region of the waveguide to overlap the output aperture and the mixing region not to overlap the output aperture and the redirecting features increase in size and/or number with respect to a distance from the light source.

17. The optical display device of any preceding claim, wherein the electrical circuitry is configured to control the light source to emit output light with a melanopic ratio of a maximum of at least 1.4.

18. The optical display device of any preceding claim, wherein the electrical circuitry is configured to control the light source to emit light with a melanopic lux to correspond to a circadian rhythm.

19. The optical display device of any preceding claim arranged to create the perception of the sky scene with distant depth.

20. The optical display device of claim 19 wherein the condition of distant depth is determined based on one or more of: gaze vectors of eyes of an observer having the same and/or a similar alignment when looking into the device as for looking at real life sky; the sky scene being absent of features with an apparent depth ZA either at the optical display device or within an apparent depth ZA of 10 times a physical depth ZD of the device; the sky scene being uniform to the extent where it does not vary by more than 10% or 20% or 30% or 40% for any given circular area on the output aperture of 10 mm or 50 mm diameter over at least 90% of the output aperture in terms of one or more of: colour; diffusivity; luminance; intensity.

21. The optical display device of any preceding claim, wherein a start time and/or end time are user adjustable for one or more of the: first time range; second time range; third time range; other time range.

22. The optical display device of any preceding claim, wherein one or more of: a colour; Melanopic lux/ratio; intensity, are user adjustable for one or more of: the first time range; second time range; third time range; other time range.

23. The optical display device of any preceding claim, comprising a mounting structure, for mounting to a ceiling or wall.

24. Use of a diffuse light generation system of an output light generation system for an optical display device to create a perception of a sky scene in output light, wherein the output light generation system comprises a light source to generate output light, and the diffuse light generation system to generate a diffuse sky light component from light from the light source, wherein electrical circuitry is configured to control the light source to emit a CCT of a maximum of at least 12,000 K and a with a colour rendering index (CRI) of at least 80.

25. A method of creating a perception of a sky scene in output light, the method comprising: projecting the output light; controlling output light of the output light generator system to emit a CCT of a maximum of at least 12,000 K and a with a colour rendering index (CRI) of at least 80.