JP2005221761A - Projection display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection display apparatus using a wire grid as a polarizing separation part, in which light emitted from a reflection type light valve can be projected without being lost. <P>SOLUTION: Rays of color light into which light is separated by a color separation optical system enter a wire grid polarization beam splitter, in which a grid of metals is disposed on a glass substrate, at an incident angle of less than 45°. The light transmitted through the wire grid polarization beam splitter enters a reflection type light valve via a field lens. The light emitted from the reflection type light valve enters the field lens again, and then enters the wire grid polarization beam splitter. Disposing the field lens between the reflection type light valve and the wire grid polarization beam splitter enables all modulated light to enter a cross dichroic prism without increasing the size of the cross dichroic prism. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a projection display device.

FIG. 4 shows the configuration of a projection display device using a reflective light valve.
The light emitted from the light source 101 is incident on an illuminating device 102 including an integrator composed of a first lens plate 102a and a second lens plate 102b, and a condenser lens 102c that superimposes a plurality of light beams emitted from the integrator on a light valve. To do. The light emitted from the illumination device 102 reflects R (red) light and G (green) light and reflects B (blue) light, and reflects B (blue) light, R ( A dichroic mirror 103B having a characteristic of transmitting red and G (green) light is incident on a cross dichroic mirror 103 arranged orthogonal to each other, and the combined light of R light and G light traveling in opposite directions to each other, B Color separation into light.

  The color-separated B light is incident on the deflecting mirror 104 with the light beam at the center of the light beam having an incident angle of less than 45 degrees, reflected, and incident on the polarization beam splitter 108B through the field lens 107B. The light incident on the polarization beam splitter 108B is incident on the polarization separator at an incident angle of less than 45 degrees and reflected, exits from the polarization beam splitter 108B, and enters the B-light reflective light valve 109B.

  On the other hand, the color-separated mixed light of R light and G light is incident on the deflecting mirror 105 at the incident angle of less than 45 degrees at the center of the light beam, reflected and incident on the R light transmitting and G light reflecting dichroic mirror 106. Incident light is incident at an angle exceeding 45 degrees. Color separation into G light reflected from the dichroic mirror 106 and R light traveling through the light, and the two triangular prisms are sandwiched between the field lenses 107G and 107R arranged for the G light and the R light, with the polarization separation portion interposed therebetween. It is incident on the polarization beam splitters 108G and 108R formed in the above. The light incident on the polarization beam splitters 108G and 108R is incident and reflected on the respective polarization separation sections at an incident angle of less than 45 degrees, and exits from the polarization beam splitter, and the polarized light of each color light is reflected to the G light reflection type light valve 109G. , Respectively, enters the R-light reflective light valve 109R. A projection display device using a wire grid as the polarization beam splitter is also known.

Each color light incident on the light valve for each color light is modulated by a color signal, reflected and emitted, and incident again on each of the polarization beam splitters 109B, 109G, and 109R, and the modulated light passes through the polarization separation unit. The light is separated as light and is incident on the cross dichroic prism 110 that performs color synthesis. The cross dichroic prism 110 is composed of an R light reflecting dichroic film 110R and a B light reflecting dichroic film 110B which are arranged orthogonal to the inside thereof. Each color light incident from different incident surfaces of the cross dichroic prism 110 is color-combined and emitted, enters a projection lens 111 having an aperture stop 111C therein, and a full-color image is projected on a screen (not shown). The dashed line in FIG. 4 indicates the center of the light beam. The dotted line in FIG. 4 indicates the outermost edge of the light beam emitted from the reflective light valve 109G.
JP 2000-1111839 A JP 2003-131212 A

  However, when a wire grid is used as a polarization separation element, the light emitted from the reflective light valve is incident on the cross dichroic prism for color synthesis without changing its numerical aperture unless a prism is arranged before and after the wire grid. There is a problem that the projected image becomes dark because a part of the light does not enter the color synthesis prism and is not projected onto the screen by the projection lens.

According to the first aspect of the present invention, in the projection type display device that modulates the light from the light source with the reflection type light valve and projects it with the projection lens, the light from the light source is polarized and incident on the reflection type light valve. A wire grid polarization beam splitter that detects light that is modulated and reflected and emitted by the reflection type light valve, and a field lens disposed between the wire grid polarization beam splitter and the reflection type light valve. A projection type display device is provided.
According to a second aspect of the present invention, there is provided a projection type display device that modulates light from a light source with a reflection type light valve and projects it with a projection lens, a color separation optical system that separates light from the light source, and the color separation Each color light is polarized and separated and incident on a reflection type light valve arranged for each color light, and each color light modulated and reflected and emitted by the reflection type light valve is arranged for each color light. A wire grid polarization beam splitter, a field lens arranged for each color light between the wire grid polarization beam splitter and the reflective light valve, and a color synthesis optical system for color-combining the analysis light of each color light A projection type display device is provided.

  According to a third aspect of the present invention, in the reflective light valve, a principal ray determined by an aperture stop disposed in the projection lens is disposed at a telecentric position parallel to the optical axis. Item 3. A projection display device according to Item 2.

According to a fourth aspect of the present invention, there is provided the projection display apparatus according to the second or third aspect, wherein the projection lens is non-telecentric on the incident side.
According to a fifth aspect of the present invention, the color separation optical system includes a first color light, a cross dichroic mirror that separates the light into a mixed light of the second color light and the third color light, and the first color light for the first color light. A first deflecting mirror that reflects on the wire grid polarization beam splitter disposed on the second deflecting mirror, a second deflecting mirror that reflects the mixed light, and the mixed light reflected by the second deflecting mirror as the second color light. And a dichroic mirror that separates the light into the third color light and guides it to a wire grid polarization beam splitter disposed for each color light. A projection display device is provided.

  In the invention according to claim 6, the first deflection mirror and the second deflection mirror are arranged so that an incident angle of an optical axis of the incident light is less than 45 degrees, The projection display apparatus according to claim 5, wherein the dichroic mirror is arranged so that an incident angle of an optical axis of incident light is greater than 45 degrees.

  According to a seventh aspect of the present invention, there is provided the projection type display apparatus according to any one of the second to sixth aspects, wherein the color synthesizing optical system is a cross dichroic prism.

  According to the present invention, there is provided a projection display device that can project light emitted from a reflective light valve without losing light in a projection display device that uses a wire grid as a polarization separator.

The best mode for carrying out the present invention will be described below with reference to the drawings. In the following description, the light beam at the center of the light beam will be described unless otherwise specified, and the incident angle is the incident angle for this light beam.
FIG. 1 shows a configuration diagram of a projection display device of the present invention. The light emitted from the light source 11 composed of a lamp and a concave mirror has a first lens plate 12a in which a plurality of lenses are arranged in a matrix shape, and the first lens plate 12a at the focal position of each lens of the first lens plate 12a. In the same manner as described above, the light is incident on an illumination optical device 12 having a second lens plate 12b in which a plurality of lenses are arranged in a matrix shape and a condenser lens 12c that superimposes and illuminates the light valve. The light emitted from the illumination optical device reflects the R light and the G light and reflects the B light, and the dichroic mirror 13RG has the characteristic of reflecting the B light and transmits the R light and the G light. 13B is incident on a cross dichroic mirror 13 arranged orthogonally to each other, and is color-separated into R light, G light, mixed light, and B light that are orthogonal to the traveling direction of the incident light and travel in opposite directions.

  The color-separated B light is reflected when the central light is incident on the deflecting mirror 15 at an incident angle of less than 45 degrees, and a metal grid is arranged on the glass substrate in a grid shape in a direction perpendicular to the paper surface. It is incident on 17B at an incident angle of less than 45 degrees. Incident light is polarized and separated into polarized light having a vibration direction parallel to the paper surface and polarized light having a direction perpendicular to the paper surface. Light polarized in the direction parallel to the paper surface is transmitted and polarized in the vertical direction. The light is reflected. The transmitted polarized light is incident on the reflective light valve 19B through the field lens 18B.

On the other hand, the color-separated mixed light of R light and G light is incident on the deflecting mirror 14 at an incident angle of less than 45 degrees, is reflected, reflects G light at an incident angle of more than 45 degrees, and reflects R light. The light is incident on the dichroic mirror 16 having transmission characteristics, and is separated into G light to be reflected and R light to be transmitted. The R light and the G light are incident on and transmitted through the wire grid polarization beam splitters 17G and 17R in which a metal grid is arranged in a direction perpendicular to the paper surface arranged at an incident angle of less than 45 degrees with respect to each color light. Polarized light is separated into reflected polarized light. The transmitted polarized light enters the reflection type light valves 19G and 19R through the field lenses 18G and 18R, respectively.
The polarized light of each color light incident on the reflection type light valves 19B, 19G, and 19R is reflected and emitted by being modulated by the respective color signals, is incident on the field lenses 18B, 18G, and 18R again, and the wire grid polarization beam splitter 17B. , 17G, and 17R. Light that has been modulated by the reflection type light valve and whose polarization direction has been changed is reflected by the wire grid polarization beam splitters 17B, 17G, and 17R as analysis light. Each of the reflected color lights has an R light reflecting dichroic film 20R and a B light reflecting dichroic film 20B arranged orthogonally to each other and enters the cross dichroic prism 20 from different incident surfaces, and the R light is reflected on the R light reflecting dichroic film 20R. The B light is reflected by the B light reflecting dichroic film 20B, and the B light is color-synthesized by passing through both dichroic films. The color-synthesized light is incident on a projection lens 21 having an aperture stop 21C therein, and a full-color image is projected on a screen (not shown).

  FIG. 2 is a diagram showing principal rays defined by the aperture stop 21C of the projection lens 21 in the projection display device of this embodiment, and the principal rays are indicated by dotted lines. The principal ray is a ray that passes through the center of the aperture stop 21C of the projection lens. FIG. 2 shows two principal rays intersecting at the center of the aperture stop 21C of the projection lens 21, and the traveling direction of these principal rays travels in a screen direction (not shown). Although the projection lens 21 has a front group lens disposed on the screen side (not shown) of the aperture stop 21C and a rear group lens disposed on the cross dichroic prism side, the illustration is omitted. The two principal rays shown in FIG. 2 are not parallel to each other on the incident side of the projection lens 21. That is, the projection lens 21 is not telecentric with respect to the incident light side, and the aperture stop 21C is not arranged at the focal position of the rear group lens.

  The two principal rays shown in FIG. 2 spread on the incident side of the projection lens 21 to the field lenses 18B, 18G, and 18R via the croissant dichroic prism 20 and the wire grid polarization beam splitters 17B, 17G, and 17R. Between the field lenses 18B, 18G, and 18R and the reflection type light valves 19B, 19G, and 19R, the principal ray is parallel to the optical axis, and the reflection type light valves 19B, 19G, and 19R are arranged at telecentric positions of the principal ray. ing. The principal ray of each color light incident on the reflection type light valve is parallel to the optical axis between the reflection type light valve and the field lenses 17B, 17G, and 17R. The chief rays are condensed by the lens on the optical axis of the second lens plate from the field lenses 17B, 17G, and 17R, through the wire grid polarization beam splitters 17B, 17G, and 17R, the deflection mirrors 14 and 15, and the cross dichroic mirror 13. It is supposed to be. The R light and the G light pass through the dichroic mirror 16.

  Accordingly, the chief rays are spread and emitted from the second lens plate 12B of the illuminating device 12, and the chief rays of each color light are spread in the optical path to the field lenses 18B, 18G, and 18R. The reflection type light valve is arranged in a telecentric position where the principal ray is parallel to the optical axis, and the principal ray reflected by the reflection type light valve becomes a ray in the direction of condensing in the optical path from the field lens to the projection lens. Yes.

  FIG. 3 shows the outermost rays as dotted lines. FIG. 3 shows the outermost edge of a light beam having a numerical aperture determined by the aperture stop 21C of the projection lens 21 from the outermost position of the image forming portion of the light valve 19G among the reflective light valves 19B, 19G, 19R. Rays are indicated by dotted lines.

Note that a and b shown in FIG. 3 indicate the outermost rays of the light beam emitted from the reflective light valve image forming unit.
The light that spreads and exits with a certain numerical aperture from each point of the image forming portion of the reflective light valve 19R is reduced by the field lenses 18B, 18G, 18R, and the wire grid polarization beam splitters 17B, 17G, The light is reflected by 17R and enters the cross dichroic prism 20. Accordingly, even if the cross dichroic prism 20 is not enlarged, all of the R light detection light emitted from the reflective light valve 19R is incident on the cross dichroic prism, so that loss of the projected light can be prevented.
Without the field lens 18R, the light that spreads and exits with a certain numerical aperture from each point of the image forming portion of the reflective light valve 19R enters the cross dichroic prism 20 with the same numerical aperture. A part of it is off the incident surface of the cross dichroic prism 20 and is not projected as a projected image, so the projected image becomes dark. As described above, by using the field lens, all the analysis lights can be incident on the cross dichroic prism 20 by reducing the numerical aperture of the light emitted from the reflection type light valve 19R.
By arranging the field lenses 18B, 18G, and 18R between the reflection type light valves 19B, 19G, and 19R and the wire grid polarization beam splitters 17B, 17G, and 17R, all the detections can be performed without enlarging the cross dichroic prism 20. Light light can be projected.
In addition, a structure in which a wire grid is sandwiched between two prisms, such as a wire grid polarization beam splitter of a conventional projection display device, can make all the analysis light incident on the cross dichroic prism. Although the polarization may be disturbed, the wire grid polarization beam splitter of the present embodiment does not disturb the polarization by the prism because the prism is not disposed before and after the wire grid.
Further, by disposing the field lenses 18B, 18G, and 18R in front of the reflection type light valves 19B, 19G, and 19R, the light valves 19B, 19G, and 19R can be used as the projection lens even if the projection lens 21 is not a telecentric optical system. It can be placed in a telecentric position relative to the chief ray defined by the aperture stop. Therefore, it is possible to minimize the characteristic that the action of the modulation process differs depending on the inclination of the light beam emitted from the reflection type light valve. Also, the polarization separation characteristic of the wire grid polarization beam splitter is less dependent on the incident angle of the incident light beam. Therefore, even if the chief ray is arranged at a non-telecentric position, there is no influence on the polarization separation / analysis function. In the cross dichroic prism, the principal ray is arranged at a non-telecentric position, but the influence on the polarization can be minimized by making the internal dichroic film less dependent on the incident angle of the ray.

  In the present embodiment, the polarized light transmitted through the wire grid polarization beam splitter is configured to enter the reflective light valve through the field lens. However, the present invention is not limited to this configuration, and the polarized beam The polarized light reflected by the splitter may be incident on the reflective light valve via the field lens.

  In this embodiment, the illumination device 12 is not provided with a polarization conversion device. However, the illumination device 12 is a prism member in which a plurality of combinations of polarization separation portions and reflection film portions are arranged after the second lens plate 12b. A polarization conversion device having a configuration in which a half-wave phase plate is attached to the exit surface portion may be disposed. In this case, the arrangement of the half-wave phase plate is determined depending on which of the polarized light transmitted through the wire grid polarization beam splitter and the transmitted polarized light is incident on the reflective light valve, and the polarization of the polarized light by the polarization converter is determined. Determine the direction of vibration.

  In addition, the optical axis of the incident light described in the claims is a light beam at the center of the incident light beam.

The block diagram of the projection type display apparatus of this invention. The figure which showed the chief ray of the projection type display apparatus of this invention. The figure which showed the outermost edge light ray of the projection type display apparatus of this invention. The block diagram of the projection type display apparatus of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Light source 12 Illumination optical system 13 Cross dichroic mirror 14, 15 Deflection mirror 16 Dichroic mirror 17R, 17G, 17B Wire grid polarizing beam splitter 18R, 18G, 18B Field lens 19R, 19G, 19B Reflection type light valve 20 Cross dichroic prism 21 Projection lens

Claims (7)

In a projection display device that modulates light from a light source with a reflective light valve and projects it with a projection lens,
A wire grid polarization beam splitter for polarizing and separating the light from the light source and making it incident on a reflective light valve, and detecting the light modulated and reflected and emitted by the reflective light valve;
A projection display device comprising: a field lens disposed between the wire grid polarization beam splitter and the reflective light valve. In a projection display device that modulates light from a light source with a reflective light valve and projects it with a projection lens,
A color separation optical system that separates light from a light source;
The color-separated color lights are polarized and separated and made incident on a reflective light valve disposed for each color light, and each color light modulated and reflected and emitted by the reflective light valve is analyzed for each color light. An arranged wire grid polarizing beam splitter;
A field lens disposed for each color light between the wire grid polarization beam splitter and the reflective light valve;
A projection type display apparatus comprising: a color synthesis optical system that performs color synthesis of the analysis light of each color light. 3. The projection display device according to claim 2, wherein the reflective light valve is disposed at a position telecentric with respect to a principal ray determined by an aperture stop disposed in the projection lens. The projection display device according to claim 2, wherein the projection lens is non-telecentric on the incident side. The color separation optical system is
A cross dichroic mirror that separates the first color light into a mixed light of the second color light and the third color light;
A first deflecting mirror for reflecting the first color light to a wire grid polarization beam splitter disposed for the first color light;
A second deflecting mirror that reflects the mixed light;
The mixed light reflected by the second deflection mirror comprises a dichroic mirror that separates the mixed light into the second color light and the third color light and guides them to a wire grid polarization beam splitter arranged for each color light. The projection display device according to claim 2, claim 3, or claim 4. The first deflection mirror and the second deflection mirror are arranged so that the incident angle of the optical axis of the incident light is less than 45 degrees,
The projection display apparatus according to claim 5, wherein the dichroic mirror is arranged so that an incident angle of an optical axis of incident light exceeds 45 degrees. The projection display device according to claim 2, wherein the color synthesis optical system is a cross dichroic prism.