WO2011162321A1 - Illumination device and projector - Google Patents

Abstract

The principal rays of the light flux emitted by a composite light source (ST) equipped with three light-emitting units (LED1-LED3) respectively emitting red light flux, green light flux or blue light flux having different wavelengths towards the same side is made to pass through first condensing optical systems (L1-L3) and is then made to enter a reflective liquid crystal display element (LC), which is a spatial light-modulating element, via a composite mirror obtained by arranging a first mirror (M1), which is a dichroic mirror that reflects red light flux but transmits green and blue light flux, a second mirror (M2), which is a dichroic mirror that reflects green light flux that has passed through the first mirror (M1) but transmits blue light flux, and a third mirror (M3), which reflects the blue light flux that has passed through the second mirror (M2), in a manner such that the mirrors have an angular difference. This configuration provides an illumination device that is smaller than conventional illumination devices, and a projector using the illumination device.

Description

Lighting device and projector

The present invention relates to a lighting device and a projector, and particularly to a lighting device suitable for a small projector and a projector using the same.

In recent years, along with the downsizing and high efficiency of spatial light modulators and light sources such as liquid crystal panels and micromirror array devices, the development of projectors that are small enough to be portable has been promoted. There is an increasing demand for further downsizing of lighting devices including the above. A certain type of projector has a function of displaying an image by guiding light from a light source to a spatial light modulation element and projecting light modulated by each modulation light modulation element onto a projection surface such as a screen. Have. Here, when forming a color image using the time division method, it is necessary to combine light from a plurality of light sources having different wavelengths and to guide the combined light to a spatial light modulator. As a method for synthesizing such light, as shown in Patent Documents 1 and 2, an illumination device for causing each color light beam from a light source to enter a spatial light modulation element via a dichroic prism (or dichroic mirror), and the same A projector equipped with is proposed.

JP 2007-108504 A JP 2009-58594 A

However, since the illumination device described in Patent Document 1 emits three light sources from different sides with respect to three sides other than the exit surface of the X-shaped cross dichroic prism, the horizontal projection area is large. It is large and disadvantageous for miniaturization. In addition, in the illumination device of Patent Document 2, the light emission directions are aligned, but since the dichroic prisms for color synthesis of each color are arranged in parallel, there is a problem that the illumination device tends to be long in one direction. Yes.

The present invention has been made in view of such problems, and an object of the present invention is to provide an illumination device and a projector that can be reduced in size as compared with the case of using a cross dichroic prism or a parallel dichroic prism. Yes.

The lighting device according to claim 1 is provided.
A spatial light modulator;
A composite light source including three light emitting units that respectively emit a first color light beam, a second color light beam, and a third color light beam having different wavelengths toward the same side;
Mirror means arranged to be tilted about a predetermined tilt axis in order to reflect the light beam from the composite light source;
A first condensing optical system including at least one lens and disposed between the composite light source and the mirror means;
The light emitting unit of the composite light source is orthogonal to an axis (first optical axis) connecting the center of the second color light emitting unit disposed at the center of the composite light source and the center of the first condensing optical system, And arranged side by side in a direction perpendicular to the tilt axis,
The principal rays of the light beams emitted from the light emitting units have an angular difference from each other after passing through the first condensing optical system,
The mirror means reflects the first color light beam from the composite light source toward the spatial light modulation element and transmits the second and third color light beams, and has passed through the first mirror. A second mirror that reflects the second color light beam toward the spatial light modulation element and transmits the third color light beam, and the third color light beam that has passed through the second mirror is directed toward the spatial light modulation element. A third mirror that reflects the first mirror, the second mirror, and the third mirror are plane mirrors that are arranged at an angle difference from each other,
Furthermore, a second condensing optical system is disposed between the mirror means and the spatial light modulator.

According to the present invention, the light emitting unit of the composite light source is orthogonal to the axis (first optical axis) connecting the center of the second color light emitting unit disposed in the center and the center of the first condensing optical system. And the principal rays of the light beams emitted from the light emitting units are arranged in a direction perpendicular to the tilt axis and have an angular difference with each other after passing through the first light collecting optical system. By aligning and adjoining the directions of the principal rays of the light emitting section, the condensing optical system can be commonly used up to the composite light source and the mirror means, and therefore the number of parts can be reduced. The mirror means includes a first mirror that reflects the first color light beam from the composite light source toward the spatial light modulation element and transmits the second and third color light beams, and the first mirror. A second mirror that reflects the passed second color light beam toward the spatial light modulation element and transmits the third color light beam, and a third color light beam that has passed through the second mirror. A first mirror, a second mirror, and a third mirror that are plane mirrors and are arranged at an angle difference from each other. The second color light flux whose principal ray coincides with the first optical axis passes through the first condensing optical system, is bent in the optical path by the second mirror, and then reaches the center of the lens immediately after the mirror portion. The light is emitted from the mirror means along a passing axis (second optical axis). On the other hand, the principal ray of the light emitting portion of the first color light flux is separated in a direction perpendicular to the first optical axis and perpendicular to the tilt axis, and passes through the first condensing optical system. Later, an angle difference is generated between the first optical axis and the principal ray of the first color light flux. Therefore, by arranging the first mirror at an appropriate angle, the principal ray of the first color light beam emitted from the mirror means can be substantially aligned with the second optical axis. Similarly, the principal ray of the light emitting portion of the third color light beam is also perpendicular to the first optical axis and away from the tilt axis, and the first condensing optical system is After passing, an angle difference is generated between the first optical axis and the principal ray of the third color light flux. Therefore, by arranging the third mirror at an appropriate angle, the principal ray of the third color light beam after exiting the mirror means can be substantially aligned with the second optical axis. As described above, after the second condensing optical system, the chief rays from the respective light emitting units can be combined light that is aligned with the second optical axis. The second light collecting optical system can converge the light beam that has become substantially parallel light in the first light collecting optical system on the image display unit of the spatial light modulation element, and can increase the illumination efficiency.

The “spatial light modulation element” is preferably, for example, a reflective liquid crystal image display element or a micromirror array device, but is not limited thereto.

The illumination device according to claim 2 is the illumination device according to claim 1, wherein the first condensing optical system satisfies the following conditional expression.
0.1 <h / f <0.3 (1)
f: Composite focal length (mm) of the first focusing optical system
h: Distance between the center of the first color light emitting unit or the center of the third color light emitting unit and the second color light emitting unit in a direction orthogonal to the first optical axis and orthogonal to the tilt axis (Mm)

Here, by increasing the lens diameter of the condensing optical system, it is possible to ensure a large numerical aperture on the light source side, but the lens diameter is usually limited by the size of the projector, so it should be increased without limit. I can't. In particular, in the case of a condensing optical system of an illuminating device intended for a small projector, the condition becomes more severe. In order to increase the numerical aperture without increasing the lens diameter, it is effective to reduce the combined focal length of the first condensing optical system. However, if this is made too small, the angle difference between the principal ray of the first color beam and the principal beam of the third color beam with respect to the optical axis of the first condensing optical system becomes large, and the chief rays of all color beams. In order to align these, it is necessary to increase the angle of the first mirror and the third mirror with respect to the second mirror, resulting in an increase in the size of the configuration. Therefore, by keeping within the range of conditional expression (1), it is possible to reduce the size of the lighting device while maintaining the brightness.

The illumination device according to claim 3 is the illumination device according to claim 2, wherein a polarization separation element is disposed between the mirror means and the spatial light modulation element, and the polarization separation element and the spatial light modulation element A condensing lens is arranged between them.

When the spatial light modulation element is a reflective liquid crystal image display element (Lcos: Liquid crystal on silicon), the polarization separation element is required. The light that has passed through the condensing optical system is reflected by the reflective liquid crystal image display element as the spatial light modulation element, and then the optical path is bent by the polarization separation element and travels in the projection direction. Therefore, in order not to reduce the light utilization rate with the polarization separation element, the size of capturing the three kinds of light as illumination light and the projection light reflected by the display area of the reflective liquid crystal image display element, respectively. Although it is necessary to have it, there exists a possibility of causing the enlargement of an illuminating device by it. Therefore, by arranging a condensing lens that can suppress the spread of the light between the polarization separation element and the spatial light modulation element, the size of the polarization separation element can be increased while maintaining the light use efficiency. It can be suppressed and downsized.

The illuminating device according to claim 4 is the illuminating device according to claim 3, and is emitted from the composite light source, the first condensing optical system, the mirror means, the second condensing optical system, and the spatial modulation element. A projection optical system that projects the emitted light, and the condensing lens is used in common by the second condensing optical system and the projection optical system. Thereby, the structure of an illuminating device can be simplified more.

The illumination device according to claim 5 is the illumination device according to any one of claims 2 to 4, wherein at least one of the first condensing optical system and the second condensing optical system is at least one surface. Has a lens with an anamorphic aspheric surface.

The illumination device according to claim 6 is the illumination device according to claim 5, wherein the aspect ratio of the composite light source is adjusted to the aspect ratio of the display region of the spatial light modulator by the anamorphic aspheric surface. Features.

Since the aspect ratio of the spatial light modulator is generally 4 to 3 or 16 to 9, when the aspect ratio of each light emitting unit is the same, the horizontal direction and the vertical direction of the spatial light modulator are the same ratio. When the illumination is performed, there is a portion that is not illuminated in the display area of the spatial light modulation element, and as a result of illuminating the outside of the image display area, the illumination light may not be used effectively. On the other hand, by using an anamorphic aspherical surface for at least one surface of the lens of the condensing optical system, the horizontal direction and the vertical direction of the illumination light can be matched with the aspect ratio of the spatial light modulator. .

The illuminating device according to claim 7 is the illuminating device according to any one of claims 1 to 6, wherein the first condensing optical system includes a first rod integrator having an inner surface tapered to each light emitting unit. In the first rod integrator, the exit end face on the first condensing optical system side is configured to have a larger area than the entrance end face on the composite light source side. And

The first rod integrator whose inner surface has a tapered shape has an inclination such that the cross-sectional size gradually increases from the incident surface toward the output surface. For this reason, when the light emitting unit emits a luminous flux having a large angular distribution such as a LED, such as an LED, the reflected light gradually approaches parallel to the optical axis while being repeatedly reflected in the first rod integrator. The spread of the luminous flux can be suppressed smaller than that immediately after the light source is emitted. In addition, the light incident on the first rod integrator is repeatedly reflected and mixed by the reflecting surface on the inner surface, so that the spatial light modulator can be illuminated uniformly. The rod integrator is described in, for example, Japanese Patent Application Laid-Open No. 2007-140344.

The illumination device according to claim 8 is the illumination device according to claim 7, wherein the shape of the emission end face of the first rod integrator is matched with the aspect ratio of the display region of the spatial light modulator. .

Even if it does not have an anamorphic aspherical surface as described above by matching the emission end face shape of the light guide portion of the first rod integrator with the aspect ratio of the display area of the spatial light modulator, the space The display area of the light modulation element can be appropriately illuminated.

The illumination device according to claim 9 is the illumination device according to claim 7 or 8, wherein the reflection-type polarizing plate disposed so as to face the emission end face of the first rod integrator, the reflection-type polarization plate, And a quarter-wave plate disposed between the first rod integrator and the first rod integrator.

In the case where the light emitting unit emits a light beam having a large angular distribution such as an LED such as an LED, most of the light repeatedly reflected in the first rod iterator is reflected in the state of skew rays and the polarization state is disturbed. It will be. For this reason, some of the light is reflected in the direction of vibration reflected by the reflective polarizing plate and can be given the effect of recycling the polarized light. You can also. However, among the light beams emitted from the composite light source, the light beam traveling in the direction close to the normal direction of the light emitting surface is less susceptible to the disturbance of the polarization state due to repeated reflection in the first rod integrator. In a system that handles such light, polarization conversion can be performed more efficiently by providing a quarter-wave plate.

The illuminating device according to claim 10 is the illuminating device according to any one of claims 2 to 6, wherein the second condensing optical system includes a second rod integrator.

The light incident on the second rod integrator is repeatedly reflected and mixed by the reflecting surface on the inner surface, so that the spatial light modulator can be illuminated uniformly.

The illumination device according to claim 11 is the illumination device according to claim 10, wherein an end surface shape of the second rod integrator on the spatial light modulation element side is matched with an aspect ratio of a display region of the spatial light modulation element. It is characterized by that.

By adjusting the emission end face shape of the second rod integrator to the aspect ratio of the display area of the spatial light modulator, the anamorphic structure as described above can be obtained. Even without a Fick aspherical surface, the display area of the spatial light modulator can be appropriately illuminated.

The illumination device according to claim 12 is the illumination device according to claim 10 or 11, wherein a total reflection prism is disposed between the second condensing optical system and the spatial light modulation element, and the space The light modulation element is a micromirror array device.

The micromirror array device has a function to turn on and off the image by reflecting the illumination light at different angles, and the polarization characteristics are used to turn on and off the image like a reflective liquid crystal image display device. Since it is not used, it is possible to perform efficient illumination without any loss due to the polarization component, and it is not necessary to perform polarization conversion. In the reflective liquid crystal image display element, the illumination light and the projection light are separated using polarized light. In the micromirror array device, the angle difference between the illumination light and the projection light is used. The total reflection prism separates illumination light and projection light by transmitting one through the angle difference and totally reflecting the other. When there is no total reflection prism, a space is required until the illumination light and projection light having an angle difference are spatially separated, and there is a possibility that both the illumination system and the projection system are enlarged. On the other hand, by using the total reflection prism, it is possible to separate the illumination light and the projection light in a region where the illumination light and the projection light are spatially overlapped, and to obtain a compact optical system such as shortening the projection lens back. Note that the micromirror array device and the total reflection prism are described in Japanese Patent Application Laid-Open No. 2007-140344.

The illumination device according to claim 13 is the illumination device according to any one of claims 1 to 12, wherein at least one polarization conversion element is disposed between the mirror means and the second condensing optical system. It is characterized by that.

When the spatial light modulation element is a reflective liquid crystal image display element (Lcos), the polarization component that can be used as projection light is limited, and thus there is a possibility that light that is not used effectively is generated. Therefore, efficient illumination can be performed by using the polarization conversion element to align the polarization component that is not effectively used with the polarization component that can be used in the reflective liquid crystal image display element. The polarization conversion element has a function of converting, for example, almost transmitted light into light having an S (P) polarization component, as described in, for example, Japanese Patent Application Laid-Open No. 2010-72138.

The illumination device according to claim 14 is the illumination device according to any one of claims 1 to 13, wherein two lens arrays are arranged between the mirror means and the second condensing optical system. It is characterized by.

For example, in the first lens array, rectangular lens cells that are substantially similar to the display area of the reflective liquid crystal image display element are arranged in a two-dimensional array. To divide. Then, a plurality of light source images are formed in the vicinity of the second lens array having the same array structure as the first lens array. The second lens array has the same number of lens cells of the same shape that are paired with the lens cells of the first lens array. Each lens cell of the first lens array and the reflective liquid crystal image display element have a conjugate relationship with respect to each lens cell of the second lens array, and each lens cell of the first lens array passes through each lens cell. The illumination light is condensed by the overlapping lens so that the conjugate image of each lens cell of the first lens array overlaps on the reflective liquid crystal image display element in this way. The spatial energy distribution of light is made uniform, and the display area of the reflective liquid crystal image display device can be illuminated uniformly without waste.

A projector according to a fifteenth aspect includes the illumination device according to any one of the first to fourteenth aspects. By using the lighting device of the present invention, the projector can be reduced in size.

According to the present invention, it is possible to provide a lighting device that is smaller than the conventional one and a projector using the same.

It is the schematic of the projector using the illuminating device concerning 1st Embodiment. It is the schematic of the projector using the illuminating device concerning 2nd Embodiment. It is the schematic of the projector using the illuminating device concerning 3rd Embodiment. It is the schematic of the projector using the illuminating device concerning 4th Embodiment. It is sectional drawing of the illuminating device of Example 1. FIG. It is sectional drawing of the illuminating device of Example 2. FIG. It is sectional drawing of the illuminating device of Example 3. FIG. It is sectional drawing of the illuminating device of Example 4. FIG. It is sectional drawing of the illuminating device of Example 5. FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a schematic diagram of a projector using the illumination device according to the first embodiment. In FIG. 1, a first light emitting unit LED1 that emits a red light beam (first color light beam), a second light emitting unit LED2 that emits a green light beam (second color light beam), and a blue light beam on a substrate ST. A third light emitting unit LED3 that emits (third color light flux) is mounted. Each light emitting section is arranged so as to emit a light beam in the same direction, and the principal rays thereof are arranged in parallel on the same plane (a plane parallel to the paper surface). Only the central axis of the second light emitting unit LED2 coincides with the optical axis of the first condensing optical system. The axis connecting the center of the second light emitting unit LED2 and the center of the first condensing optical system is the first optical axis. Each light emitting part is a 0.75 mm square light emitting diode, and these constitute a composite light source.

The first lens L1, the second lens L2, and the third lens L3 are disposed in order from the composite light source, and constitute a first condensing optical system. On the exit side of the third lens L3, a composite mirror that is a mirror means is arranged. By passing through the first condensing optical system, the chief rays of the first light emitting unit LED1 and the third light emitting unit LED3 are given an angular difference with respect to the chief ray (that is, the optical axis) of the second light emitting unit LED2. The composite mirror is a dichroic mirror that reflects the red light beam but transmits the green and blue light beams, and reflects the green light beam that has passed through the first mirror M1 but transmits the blue light beam. There is a second mirror M2 and a third mirror M3 that reflects the blue light beam that has passed through the second mirror M2. The first mirror M1, the second mirror M2, and the third mirror M3 are incident on the main mirrors. They are arranged with an angle difference from each other according to the angle difference of the light rays. That is, the first mirror M1, the second mirror M2, and the third mirror M3 are arranged at different angles around arbitrary tilt axes extending in the direction perpendicular to the paper surface in FIG. The second light emitting unit LED2 and the third light emitting unit LED3 are arranged in a direction perpendicular to the tilt axis and perpendicular to the first optical axis.

The fourth lens L4 and the fifth lens L5, which are condensing lenses, are arranged in this order on the exit side of the composite mirror, and these constitute a second condensing optical system. Between the fourth lens L4 and the fifth lens L5, a wire grid WG as a polarization separation element is disposed. On the emission side of the fifth lens L5, a cover glass CG and a reflective liquid crystal image display element LC which is a spatial light modulation element are arranged.

A sixth lens L6, a seventh lens L7, an eighth lens L8, and a ninth lens L9 are sequentially arranged at the tip of the light beam branched by the wire grid WG, and are projected by these and the fifth lens L5. Configure the optical system. That is, the fifth lens L5 is used in common for the second condensing optical system and the projection optical system. Incidentally, at least one of the lenses of the first condensing optical system or the second condensing optical system has an anamorphic aspheric surface. The anamorphic aspherical surface matches the aspect ratio of the light emitting portion with the aspect ratio of the display area of the reflective liquid crystal image display element LC.

Describes the operation of the projector. The red light beam emitted from the first light emitting unit LED1 passes through the first lens L1, the second lens L2, and the third lens L3, is converted into a substantially parallel light beam, and is the first mirror M1 that is the foremost among the composite mirrors. And is directed toward the fourth lens L4. The green light beam emitted from the second light emitting unit LED2 passes through the first lens L1, the second lens L2, and the third lens L3 and is converted into a substantially parallel light beam, and then passes through the first mirror M1 among the composite mirrors. Are reflected by the second mirror 2 toward the fourth lens L4. The blue light beam emitted from the third light emitting unit LED3 passes through the first lens L1, the second lens L2, and the third lens L3 and is converted into a substantially parallel light beam, and among the composite mirrors, the first mirror M1 and the second mirror. It passes through M2 and is reflected by the next third mirror M3, and travels toward the fourth lens L4. At this time, the principal ray of each light beam reflected from the first mirror M1, the second mirror M2, and the third mirror M3 coincides with the optical axis (second optical axis) of the second condensing optical system.

Each color light beam that has passed through the fourth lens L4 passes through the wire grid WG, passes through the cover glass CG, and is condensed on the display area of the reflective liquid crystal image display element LC through the fifth lens L5. By turning on and off for each pixel in the display area in a time division manner, the reflected light is modulated and an image is formed accordingly. The reflected light from the reflective liquid crystal image display element LC is reflected by the wire grid WG. The light beam reflected by the wire grid WG is enlarged and projected via the projection optical system (L6 to L9) to form an image on the screen SC.

(Second Embodiment)
FIG. 2 is a schematic diagram of a projector using the illumination device according to the second embodiment. In the present embodiment, a first lot integrator RI1 having a taper shape belonging to the first condensing optical system is arranged corresponding to each light emitting unit immediately after the light emitting unit. In the first lot integrator RI1, the exit end face on the first condensing optical system side has a larger area than the incident end face on the light source side. The shape of the emission end face of the first lot integrator RI1 is matched to the aspect ratio of the display area of the reflective liquid crystal image display element LC. Further, a reflection type polarizing plate RP disposed so as to face the emission end face of the first lot integrator RI, and a quarter wavelength plate QWP disposed between the reflection type polarizing plate RP and the first lot integrator RI1. Have. In this embodiment, an anamorphic aspheric surface is not necessary. The first lot integrator RI1, the reflective polarizing plate RP, and the quarter wavelength plate QWP have the functions described above.

The red light beam emitted from the first light emitting unit LED1 is a first lot integrator RI, a reflective polarizing plate RP, a quarter wavelength plate QWP, a first lens L1, and a second lens L2 that constitute the first condensing optical system. Is converted into a substantially parallel light beam, reflected by the first mirror M1 that is closest to the composite mirror, and travels toward the fourth lens L4. The green light beam emitted from the second light emitting unit LED2 is a first lot integrator RI, a reflective polarizing plate RP, a quarter wavelength plate QWP, a first lens L1, and a second lens L2 that constitute the first condensing optical system. Is converted into a substantially parallel light beam, passes through the first mirror M1 of the composite mirror, is reflected by the next second mirror 2, and travels toward the fourth lens L4. The blue light beam emitted from the third light emitting unit LED3 is a first lot integrator RI, a reflective polarizing plate RP, a quarter wavelength plate QWP, a first lens L1, and a second lens L2 that constitute the first condensing optical system. Is converted into a substantially parallel light beam, passes through the first mirror M1 and the second mirror M2 of the composite mirror, is reflected by the next third mirror M3, and travels toward the fourth lens L4.

Each color light flux that has passed through the fourth lens L4 passes through the wire grid WG and the cover glass CG, and is condensed on the display area of the reflective liquid crystal image display element LC via the fifth lens L5. By turning on and off for each pixel in the display area in a time division manner, the reflected light is modulated and an image is formed accordingly. The reflected light from the reflective liquid crystal image display element LC passes through the cover glass CG again and is reflected by the wire grid WG. The light beam reflected by the wire grid WG is enlarged and projected through the projection optical system (L6 to L9) in the same manner as described above to form an image on the screen.

(Third embodiment)
FIG. 3 is a schematic diagram of a projector using the illumination device according to the third embodiment. In the present embodiment, the second rod integrator RI2 is arranged as a part of the second condensing optical system. The shape of the emission end face of the second rod integrator RI2 is matched to the aspect ratio of the display area of the reflective liquid crystal image display element LC. Further, a total reflection prism RZ is disposed after the second light collecting optical system, and a micromirror array device DM is disposed as a spatial light modulation element. The micromirror array device DM has the functions described above.

The red light beam emitted from the first light emitting unit LED1 passes through the first lens L1 and the second lens L2, is converted into a substantially parallel light beam, is reflected by the first mirror M1 which is the foremost among the composite mirrors, Head toward 4 lens L4. The green light beam emitted from the second light emitting unit LED2 passes through the first lens L1 and the second lens L2, is converted into a substantially parallel light beam, passes through the first mirror M1 among the composite mirrors, and the next second mirror 2. And is directed toward the fourth lens L4. The blue light beam emitted from the third light emitting unit LED3 passes through the first lens L1 and the second lens L2 and is converted into a substantially parallel light beam, and then passes through the first mirror M1 and the second mirror M2 among the composite mirrors. Is reflected by the third mirror M3 toward the fourth lens L4.

The color light beams that have passed through the fourth lens L4 are mixed by passing through the second rod integrator RI2, pass through the fifth lenses L5a and L5b, are reflected by the total reflection prism RZ, and are displayed in the display area of the micromirror array device DM. It is focused on. By turning on and off for each pixel in the display area in a time division manner, the reflected light is modulated and an image is formed accordingly. The reflected light from the micromirror array device DM passes through the total reflection prism RZ, and is enlarged and projected through the projection optical system (L6 to L9) in the same manner as described above, thereby forming an image on the screen. .

(Fourth embodiment)
FIG. 4 is a schematic diagram of a projector using the illumination device according to the fourth embodiment. In the present embodiment, a polarization conversion element PD having a function of adjusting a polarization component and two lens arrays LA are arranged between the composite mirror and the second condensing optical system.

The red light beam emitted from the first light emitting unit LED1 passes through the first lens L1 and the second lens L2, is converted into a substantially parallel light beam, is reflected by the first mirror M1 which is the foremost of the composite mirrors, and is polarized. It goes to the conversion element PD. The green light beam emitted from the second light emitting unit LED2 passes through the first lens L1 and the second lens L2, is converted into a substantially parallel light beam, passes through the first mirror M1 among the composite mirrors, and the next second mirror 2. Is reflected toward the polarization conversion element PD. The blue light beam emitted from the third light emitting unit LED3 passes through the first lens L1 and the second lens L2 and is converted into a substantially parallel light beam, and then passes through the first mirror M1 and the second mirror M2 among the composite mirrors. Are reflected by the third mirror M3 toward the polarization conversion element PD.

Each color light beam that has passed through the polarization conversion element PD and the two lens arrays LA passes through the fourth lens L4, the wire grid WG, and the fifth lens L5, passes through the cover glass CG, and passes through the cover glass CG. Focused on the display area. By turning on and off for each pixel in the display area in a time division manner, the reflected light is modulated and an image is formed accordingly. The reflected light from the reflective liquid crystal image display element LC passes through the cover glass CG and the fifth lens L5, is reflected by the wire grid WG, and is enlarged and projected through the projection optical system (L6 to L9) as described above. An image is formed on the screen.

Examples of the illumination optical system of the present invention are shown below. In each embodiment, the shape of the aspherical surface is expressed by the following equation 1 with the vertex of the surface as the origin, the X axis in the optical axis direction, and the height in the direction perpendicular to the optical axis as h. Here, referring to FIG. 1, a plane including the optical axis of the light emitting unit is defined as a YZ plane, and an axis orthogonal thereto is defined as an X axis. The angular arrangement of the composite mirror and the position of the fourth lens L4 are determined based on the emission surface side reference of the third lens L3 along the optical axis of the light emitting unit LED2 of the green light beam. Further, the positions of the wire grid WG and the fourth lens L4 are determined by the emission surface side reference of the fourth lens L4 along the chief ray of the light emitting part LED2 of the green light flux. Further, in FIG. 1, the inclination angle of the mirror and the wire grid is shown with 0 degree in the direction orthogonal to the first optical axis (Z-axis upward direction) and positive in the counterclockwise direction.

　但し、
　Ａｉ：ｉ次の非球面係数（ｉ＝３，４，５，６，・・・・２０）
　Ｒ：曲率半径
　Ｋ：円錐定数
　また、非球面係数において、１０のべき乗数（例えば２．５×１０^-02）を、Ｅ（例えば２．５Ｅ－０２）を用いて表している。実施例の表中、「球」とは球面を意味し、「アナモ」とはアナモルフィック非球面を意味する。

However,
Ai: i-order aspherical coefficient (i = 3,4,5,6,... 20)
R: radius of curvature K: conic constant Further, in the aspheric coefficient, a power of 10 (for example, 2.5 × 10 ⁻⁰² ) is expressed by using E (for example, 2.5E-02). In the tables of the examples, “sphere” means a spherical surface, and “anamo” means an anamorphic aspheric surface.

Example 1
The optical system data of Example 1 are shown in Table 1, Table 2, and Table 3. FIG. 5 is a cross-sectional view of the illumination device of the first embodiment. In this embodiment, the entrance surface of the third lens L3 and the exit surface of the fourth lens L4 are anamorphic aspheric surfaces, and the fifth lens L5 is common to the condensing optical system and the projection optical system.

(Example 2)
Tables 4 and 5 show optical system data of Example 2. FIG. 6 is a cross-sectional view of the illumination device of the second embodiment. In this embodiment, the entrance surface of the third lens L3 and the exit surface of the fourth lens L4 are anamorphic aspheric surfaces, and the fifth lens L5 is common to the condensing optical system and the projection optical system. Since the projection optical system is the same as that of the first embodiment, it will not be described below.

(Example 3)
The optical system data of Example 3 are shown in Tables 6 and 7. FIG. 7 is a cross-sectional view of the illumination device of the third embodiment. In the present embodiment, the fifth lens L5 is common to the condensing optical system and the projection optical system. Note that the projection optical system is an optical system including the fifth lens L5, which will not be described below.

Example 4
Tables 8 and 9 show the optical system data of Example 4. FIG. 8 is a cross-sectional view of the illumination device of the fourth embodiment. In this embodiment, the entrance surface of the third lens L3 and the exit surface of the fourth lens L4 are anamorphic aspheric surfaces, and the fifth lens L5 is common to the condensing optical system and the projection optical system. Note that the projection optical system is an optical system including the fifth lens L5, which will not be described below.

(Example 5)
Tables 10 and 11 show the optical system data of Example 5. FIG. 9 is a cross-sectional view of the illumination device according to the fourth embodiment. In this embodiment, the entrance surface of the third lens L3 and the exit surface of the fourth lens L4 are anamorphic aspheric surfaces, and the fifth lens L5 is common to the condensing optical system and the projection optical system. The projection optical system is an optical system including the fifth lens L5, and will not be described below.

Table 12 shows values of the examples corresponding to the respective conditional expressions.

Note that the present invention is not limited to the embodiments and examples described in this specification, and includes other embodiments and modified examples. It will be clear to those skilled in the art from the technical idea.

According to the present invention, it is possible to provide an illumination device that is optimal for downsizing a projector.

CG Cover glass DM Micro mirror array device L1 1st lens L2 2nd lens L3 3rd lens L4 4th lens L5, L5a, L5b 5th lens L6 6th lens L7 7th lens L8 8th lens L9 9th lens LA lens Array LC Reflective liquid crystal image display element LED1 Red light emitting part LED2 Green light emitting part LED3 Blue light emitting part M1 First mirror M2 Second mirror M3 Third mirror PD Polarization conversion element QWP 1/4 wavelength plate RI lot Integrator RI1 First lot integrator RI2 Second rod integrator RP Reflective polarizing plate RZ Total reflection prism SC Screen ST Substrate WG Wire grid

Claims (15)

A spatial light modulator;
A composite light source including three light emitting units that respectively emit a first color light beam, a second color light beam, and a third color light beam having different wavelengths toward the same side;
Mirror means arranged to be tilted about a predetermined tilt axis in order to reflect the light beam from the composite light source;
A first condensing optical system including at least one lens and disposed between the composite light source and the mirror means;
The light emitting unit of the composite light source is orthogonal to an axis (first optical axis) connecting the center of the second color light emitting unit disposed at the center of the composite light source and the center of the first condensing optical system, And arranged side by side in a direction perpendicular to the tilt axis,
The principal rays of the light beams emitted from the light emitting units pass through the first condensing optical system and then have an angular difference from each other.
The mirror means reflects the first color light beam from the composite light source toward the spatial light modulation element and transmits the second and third color light beams, and passes through the first mirror. A second mirror that reflects the second color light beam toward the spatial light modulation element and transmits the third color light beam, and the third color light beam that has passed through the second mirror is directed toward the spatial light modulation element. A third mirror that reflects the first mirror, the second mirror, and the third mirror are planar mirrors that are arranged at an angular difference from each other,
Furthermore, a second condensing optical system is disposed between the mirror means and the spatial light modulation element. The illumination apparatus according to claim 1, wherein the first condensing optical system satisfies the following conditional expression.
0.1 <h / f <0.3 (1)
f: Composite focal length (mm) of the first focusing optical system
h: Distance between the center of the first color light emitting unit or the center of the third color light emitting unit and the second color light emitting unit in a direction orthogonal to the first optical axis and orthogonal to the tilt axis (Mm) The illumination according to claim 2, wherein a polarization separation element is disposed between the mirror means and the spatial light modulation element, and a condenser lens is disposed between the polarization separation element and the spatial light modulation element. apparatus. A projection optical system for projecting the light emitted from the composite light source, the first condensing optical system, the mirror means, the second condensing optical system, and the spatial modulation element; The illuminating device according to claim 3, wherein the condensing optical system and the projection optical system are used in common. 5. The device according to claim 2, wherein at least one of the first condensing optical system and the second condensing optical system includes a lens having at least one anamorphic aspheric surface. The lighting device described. 6. The illumination device according to claim 5, wherein the anamorphic aspheric surface matches the aspect ratio of the composite light source with the aspect ratio of the display area of the spatial light modulator. The first condensing optical system includes a first rod integrator having a tapered inner surface corresponding to each light emitting portion, and the first rod integrator is disposed on the first condensing optical system side. The illumination device according to any one of claims 1 to 6, wherein the exit end surface is configured to have a larger area than the entrance end surface on the composite light source side. The lighting device according to claim 7, wherein a shape of an emission end face of the first rod integrator is matched with an aspect ratio of a display area of the spatial light modulator. A reflection-type polarizing plate disposed so as to face the emission end face of the first rod integrator; and a quarter-wave plate disposed between the reflection-type polarizing plate and the first rod integrator. The lighting device according to claim 7 or 8. The illumination device according to any one of claims 2 to 6, wherein the second condensing optical system includes a second rod integrator. The lighting device according to claim 10, wherein an end surface shape of the second rod integrator on the spatial light modulation element side is matched with an aspect ratio of a display area of the spatial light modulation element. The total reflection prism is arrange | positioned between the said 2nd condensing optical system and the said spatial light modulation element, The said spatial light modulation element is a micromirror array device, It is characterized by the above-mentioned. Lighting equipment. The lighting device according to any one of claims 1 to 12, wherein at least one polarization conversion element is disposed between the mirror means and the second condensing optical system. The illumination device according to any one of claims 1 to 13, wherein two lens arrays are arranged between the mirror means and the second condensing optical system. A projector comprising the lighting device according to any one of claims 1 to 14.

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