WO1996034310A1

WO1996034310A1 - Display panels

Info

Publication number: WO1996034310A1
Application number: PCT/GB1996/000984
Authority: WO
Inventors: Nicholas Hugh Bourne; David Philip Burke; Richard Wynford Evans
Original assignee: LIVE WIRE CONTRACTORS Ltd
Current assignee: LIVE WIRE CONTRACTORS Ltd
Priority date: 1995-04-26
Filing date: 1996-04-25
Publication date: 1996-10-31
Anticipated expiration: 1997-10-26
Also published as: AU5404796A; GB9508500D0

Abstract

A display panel (2) incorporated into an item of clothing (1) or the like comprises a dye or other substance that changes colour with heat. A heating element is incorporated at the rear of the panel to produce a colour change and thus reveal a picture, text or advertising material. The heating element is powered by pulses triggered from a sound or other sensor (4) responsive to a suitable triggering stimulus.

Description

DISPLAY PANELS

TECHNICAL FIELD OF THE INVENTION

This invention relates to display panels for producing an unexpected visual effect such as the appearance of a coloured picture, message or advertising material.

BACKGROUND

Manufacturers and traders are constantly looking for new ways of increasing the demand for their products and services. One way of increasing such demand is to advertise in new and innovative ways. In the case of a product, another way is to incorporate a novel and eye-catching feature.

The present invention seeks to provide a display panel which is patentably different from any known form of display panel.

SUMMARY OF THE INVENTION

The present invention proposes a display panel comprising a heat-sensitive sheet having a display surface and an opposed rear surface, said sheet incorporating a substance which causes the said display surface to undergo a change in its light-reflective properties when said layer is heated, characterised by electrical resistance heating means closely juxtaposed to selected areas of said sheet such that, when electrical power is applied to said heating means, said selected areas of the sheet are heated causing corresponding areas of the display surface to change its visual apprearance.

The panel may be rigid or flexible.

The display surface preferably undergoes a change in its light-reflective properties when heated. In a preferred form, the wavelength of the reflected light changes so that the panel undergoes a visible colour change.

The heating means may be arranged in the shape of an advertising logo or other material. The sheet may include a hypercolour dye (i.e. a dye which temporarily changes colour on application of heat).

Although the heating means may be integrally incorporated in the sheet it is preferably applied to the rear surface of the sheet so that it is not visible from the display surface. The heating means may be secured to a carrier layer which is in turn applied to said rear surface of the sheet. A preferred form of heating means comprises an elongate electrically conductive resistance heating element.

The heating means is preferably operated by sensor means which is arranged to produce electrical output signals in response to a predetermined triggering „.„...„ 96/34310

stimulus. The sensor means may be responsive to various triggering stimuli, including one of more of the following:

- Sounds which exceed a predetermined volume.

- Sounds which fall within a predetermined range of pitch.

- Sounds having more complex characteristics (e.g. tones, sequences of tones or voice recognition).

- Touch.

- Proximity.

- Heat.

The output signals from the sensor means may be fed to electronic signal processing means which produces electrical signals for driving the heating means. The processing means may comprise analogue electronics, combined analogue and digital electronics or a microcontroller.

In order to reduce power consumption the output signals preferably comprise a series of pulses which power the heating means. The pulses may be separated by relatively long gaps. With such an arrangement it has been found that the initial colour change is extremely rapid, but new colour may be sustained between the pulses without and notable fluctuation.

The invention also provides a display panel comprising:

- a sheet having a display surface and incorporating a substance which causes the said display surface to undergo a visible change under certain conditions,

- sensor means which is responsive to a triggering stimulus to produce electrical output signals, and

- means for producing a change in the light-reflective properties of said display surface in response to said output signals. BRIEF DESCRIPTION OF THE DRAWINGS

The following description and the accompanying drawings referred to therein are included by way of non-limiting example in order to illustrate how the invention may be put into practice. In the drawings:

Figure 1 is a general perspective view of a sweat shirt incorporating a display panel in accordance with the invention, and

Figure 2 is a block diagram of part of the sweat shirt.

DETAILED DESCRIPTION OF THE DRAWINGS

An item of clothing 1 (in this case a sweat shirt) is formed of cotton or other natural or synthetic textile materials. A design 2 is printed on an area of the shirt using a hypercolour dye which undergoes a temporary colour change when heated. A strip 3 (Fig. 2) of polyamide material incorporating a woven electrically conductive yarn is bonded to the rear (inside) surface of the shirt in registration with the design 2 using a general purpose adhesive. In the example shown, the strip measured about 7mm x 200mm and had a resistance of about 10 ohms. The electrically conductive yarn comprises a bundle of extremely fine flexible electrically conductive fibres each being electrically insulated.

In a preferred form of the invention the hypercolour dye is applied uniformly to an area of the garment so that the design is formed solely by the shape of the electrical heating element 3 and is not normally visible on the outside surface of the garment.

The shirt also incorporates an integral waterproof pouch 4 which is conveniently concealed by being incorporated into a false pocket, badge or a seam of the garment. The pouch contains a sound sensor 5 in the form of a miniature microphone which was connected to a controller card 6 including a variable gain amplifier 7. The gain of the amplifier is automatically controlled to give a large dynamic range, so that the amplifier responds to a relative change in ambient noise level rather than the absolute level. The signal received by the sensor 5 is thus processed by being amplified and peak detected to give an amplitude envelope which is compared with an adjustable reference voltage to produce a series of pulses. The pulses are stretched by a timer to about 1 second and used to drive a switching device 8 which drives the strip 3 via wires 15 bonded to the opposite ends of the strip.

Applying a 1 second pulse to the strip using a 9 volt battery draws a current of less than 1 ampere and produces sufficient heat to generate a rapid change in colour in those areas of the garment which are immediately juxtaposed to the heating element. Clearly, the dye or other substance will be chosen such that the temperature at which it undergoes the colour change will be above room temperature and, in the case of a garment, this will normally be above body temperature, e.g. around 40-60°C. Above this range power may be wasted.

The card 6 is under the overall control of a microcontroller 10, which allows more sophisticated sound recognition to be employed if desired. Re-triggering of the switching device is inhibited for a period of up to one minute, which is significantly less than the time taken for the dye to revert to its original colour. After this period, re-triggering causes another one second heating pulse to be sent to the strip 3. Clearly the duration of the pulses and the intervening gaps will depend on the characteristic speed of colour change of the dye or other substance used.

The duration of the pulses and/or the gap between them may be controlled according to ambient temperature, by incorporating a suitable temperature sensor. This can significantly increase battery life. The card is powered by a long-life lithium battery 12. Such a battery is capable of delivering several thousand one second pulses, giving a typical working life of between thirty and fifty hours.

Apart from using an area of electrically conductive material to heat the dye it would also be possible to use discrete resistance heating wires or lengths of conductive yarn arranged in a suitable pattern. The element may be sown into the garment fabric if desired, although a more impressive effect is produced if the element is applied to the rear of the fabric where it is not visible until energised to produce a colour change in the fabric.

Although a garment has been used to exemplify the invention it will be appreciated that similar flexible, rigid or semi-rigid panels could be incorporated into other articles used interior or exterior to a building, such as articles of furniture, walls, floors and windows. The occurrence of a suitable triggering stimulus can thus be arranged to produce an unexpected effect in the form of a picture, text or advertising material which was not previously visible. In such other applications the temperature at which the colour change occurs will depend upon factors such as ambient temperature. Panels can currently be produced which change colour at a selected temperature anywhere in the range -20 to + 100°C.

Whilst the above description lays emphasis on those areas which, in combination, are believed to be new, protection is claimed for any inventive combination of the features disclosed herein.

Claims

1. A display panel (1) comprising a heat-sensitive sheet having a display surface and an opposed rear surface, said sheet incorporating a substance which causes the said display surface to undergo a change in its light-reflective properties when said layer is heated, characterised by electrical resistance heating means (3) closely juxtaposed to selected areas (2) of said sheet such that, when electrical power is applied to said heating means, said selected areas of the sheet are heated causing corresponding areas of the display surface to change its visual apprearance.

2. A display panel according to Claim 1, in which said display surface undergoes a visible colour change when heated by said heating means.

3. A display panel according to Claim 1 , in which said heating means is applied to the rear surface of said sheet.

4. A display panel according to Claim 3, in which said heating means is secured to a carrier layer which is in turn applied to said rear surface of the sheet.

5. A display panel according to Claim 1, in which said heating means comprises an elongate electrically conductive reistance heating element.

6. A display panel according to Claim 1 , in which said heating means is operated by sensor means which is arranged to produce electrical output signals in response to a predetermined triggering stimulus.

7. A display panel according to Claim 6, in which said sensor means is responsive to sounds.

8. A display panel according to Claim 6, in which the output signals from said sensor means are fed to electronic signal processing means which produces electrical signals for driving said heating means.

9. A display panel according to Claim 1 , in which the heating means is driven by a series of electrical pulses.

10. A display panel according to Claim 9, in which said pulses are separated by relatively long gaps.