JP2008165086A - Projection image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve image display of a high contrast ratio by achieving a short focal length and miniaturization of a projection lens and cost reduction of glass material cost, and preventing color shift on a screen, in a projection image display device using a three-eye projection system. <P>SOLUTION: The projection image display device includes first to third projection units 1, 2, 3. The projection unit 1, 2, 3 have: spatial light modulation elements 5R, 5G, 5B illuminated by light from semiconductor light sources 4R, 4G, 4B, respectively; and projection lenses 7R, 7G, 7B for projecting light reflected on wire grid reflection polarizing plates 6R, 6G, 6B through the spatial light modulation elements 5R, 5G, 5B, respectively, on the screen 101. The projection units are arranged in a state where each is positioned at each vertex of a triangle and display color images by synthesizing images of respective colors on the screen 101. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a projection type image display apparatus using a semiconductor light source.

  2. Description of the Related Art Conventionally, there has been proposed a projection type image display apparatus that displays an image by illuminating a spatial modulation element with light from a light source and projecting the light that has passed through the spatial modulation element onto a screen by a projection lens.

  As such a projection-type image display device, a first spatial modulation element that is illuminated by light of a first color (for example, red) and a second that is illuminated by light of a second color (for example, green). And a third spatial modulation element illuminated by light of a third color (for example, blue), and the light passing through each of the spatial modulation elements is synthesized by a color synthesis optical system, An apparatus (so-called monocular projection type projection image display apparatus) that projects onto a screen by a projection lens has been proposed.

  In Patent Document 1, light from a white light source is color-separated by a color separation optical system, and light of first to third colors (red, green, and blue) subjected to color separation is first to third. Each spatial modulation element is illuminated in correspondence with the spatial modulation element, and light passing through each spatial modulation element is projected onto a screen by three projection lenses corresponding to each spatial modulation element, and color synthesis is performed on the screen. An apparatus (so-called three-eye projection type projection type image display apparatus) is described.

US Pat. No. 6,431,709

  By the way, in the above-described projection type image display apparatus of the monocular projection system, since the color synthesis optical system must be disposed between each spatial modulation element and the projection lens, the back focus of the projection lens is sufficiently long. There is a need to. For this reason, it is difficult to reduce the focal length and size of the projection lens, leading to an increase in the size of the apparatus and an increase in manufacturing cost.

  In addition, the color synthesis optical system includes a prism such as a cross dichroic prism, and its characteristics are affected by the incident angle of incident light. Therefore, it is necessary for the projection lens to have a pupil position close to telecentricity, and the rear group of the projection lens becomes large, resulting in an increase in the size of the apparatus and an increase in manufacturing cost.

  Further, in the projection lens, correction of chromatic aberration must be performed over a wide band, and there is a possibility that the cost of the glass material will increase due to the necessity of using anomalous dispersion glass.

  Furthermore, since the cross dichroic prism of the color synthesis optical system has a surface parallel to the surface of the spatial light modulator, the reflected light on this surface reduces the contrast in black display (increases the black level). May occur.

  And in the above-mentioned projection type image display apparatus of the three-eye projection system, the distance between the projection lenses for projecting images of different colors is increased by having the color separation optical system that separates the light from the white light source. A color shift may occur on the screen as the viewpoint is moved.

  In addition, in the color separation optical system, it is necessary to make the optical path length of each color light the same, so there is less freedom in the arrangement of the projection lens for each color, and the projection magnification adjustment and registration of the projection lens for each color There is a problem that restrictions on adjustment are large.

  Therefore, the present invention has been proposed in view of the above-described circumstances, and is a projection type image display apparatus using a three-lens projection method, in which the projection lens is shortened in focus, downsized, and the glass material cost is low. The distance between the projection lenses is shortened, color shift is prevented on the screen, high contrast ratio image display is realized, and contrast reduction in black display is prevented. It is an object of the present invention to provide a projection type image display device with improved performance.

  Furthermore, the present invention provides a projection-type image display device in which image distortion is reduced by optimizing each projection lens while realizing a thinner and smaller device configuration by bending the optical path with an aspherical reflecting mirror. The purpose is to provide.

  In order to solve the above-described problems and achieve the object, a projection-type image display apparatus according to the present invention has any one of the following configurations.

[Configuration 1]
A first semiconductor light source that emits light of the first color among the three primary colors, a first spatial light modulator that is illuminated by light from the first semiconductor light source, and the first spatial light modulator. A first projection unit having a first projection lens that projects light reflected by the first wire grid reflective polarizing plate onto a screen; and a second that emits light of a second color of the three primary colors. A light source reflected by the second wire grid reflective polarizing plate through the semiconductor light source, the second spatial light modulation element illuminated by the light from the second semiconductor light source, and the second spatial light modulation element is screened Illuminated by a second projection unit having a second projection lens for projecting to the third semiconductor light source, a third semiconductor light source that emits light of the third color among the three primary colors, and light from the third semiconductor light source Third spatial light modulator and this third sky A third projection unit having a third projection lens for projecting the light reflected by the third wire grid reflective polarizing plate through the light modulation element onto the screen, and each projection unit has a respective optical axis. Are arranged at positions where the distances from the optical axes of the other two projection units are substantially equal, and the color images are displayed on the screen by combining the images of the respective colors. .

[Configuration 2]
The projection type image display apparatus having the configuration 1 includes an aspheric reflecting mirror that reflects light projected by each projection unit and guides it to a screen, and the projection lens in each projection unit compensates for image distortion generated in the aspheric reflecting mirror. It is characterized by having an aspheric lens.

[Configuration 3]
In the projection type image display apparatus having the configuration 1, the projection lens in each projection unit has a bending structure that bends the optical axis, and each projection lens has different angles for bending the optical axis, It has an aspheric lens that compensates for image distortion caused by a difference in relative position with respect to the screen.

[Configuration 4]
In the projection type image display apparatus having any one of Configurations 1 to 3, the semiconductor light source in each projection unit is an LED.

[Configuration 5]
In the projection type image display apparatus having any one of Configurations 1 to 4, the spatial light modulation element in each projection unit is a reflective spatial light modulation device.

  In the projection type image display apparatus according to the present invention having the configuration 1, the optical axes are arranged at positions where the distances from the optical axes of the other two projection units are substantially equal, and the images of the respective colors are synthesized on the screen. Since each projection unit that displays a color image projects light from a semiconductor light source reflected by a wire grid reflective polarizing plate through a spatial light modulation element onto a screen, there is no color synthesis optical system, The back focus of the projection lens can be shortened, and the size and cost of each projection lens can be reduced. Further, in this projection type image display device, since the wire grid reflection type polarizing plate has characteristics that are not easily influenced by the incident angle of incident light, each projection lens can be configured to be non-telecentric, Each projection lens can be reduced in size and cost.

  In this projection type image display apparatus, the distance between the projection lenses can be shortened, the apparatus configuration can be reduced, the degree of freedom in arrangement of the apparatus is improved, and the registration performance Can be improved.

  Further, in this projection type image display device, it is possible to display an image with a high contrast ratio, and since there is no white incident surface parallel to the spatial light modulation element, a reduction in contrast in black display is prevented. be able to.

  In the projection type image display apparatus according to the present invention having the configuration 2, the projection lens in each projection unit compensates for image distortion generated in the aspherical reflector that reflects the light projected by each projection unit and guides it to the screen. Since the spherical lens is provided, the apparatus configuration can be reduced in thickness and size, image distortion can be prevented, and good image display can be performed.

  In the projection type image display apparatus according to the present invention having the configuration 3, the projection lens in each projection unit has a folding structure that bends the optical axis, and each projection lens has an angle that causes the optical axis to be bent. Different from each other and having an aspherical lens that compensates for image distortion caused by the difference in relative position with respect to the screen, it is possible to prevent image distortion and to display a good image while reducing the thickness and size of the apparatus. it can.

  In the projection type image display apparatus according to the present invention having the configuration 4, since the semiconductor light source in each projection unit is an LED, it is possible to perform image display with good color reproducibility.

  In the projection type image display apparatus according to the present invention having the configuration 5, since the spatial light modulation element in each projection unit is a reflection type spatial light modulation element, a good image display can be achieved while reducing the size of the apparatus configuration. It can be carried out.

  That is, the present invention is a projection-type image display device using a three-lens projection method, the distance between the projection lenses is shortened while shortening the focus of the projection lens, reducing the size and reducing the glass material cost, Providing a projection-type image display device that prevents color shift on the screen and displays an image with a high contrast ratio, prevents a decrease in contrast in black display, and improves registration performance Is something that can be done.

  Furthermore, the present invention provides a projection-type image display device in which image distortion is reduced by optimizing each projection lens while realizing downsizing of the device configuration by bending the optical path with an aspherical reflecting mirror. It is something that can be done.

  Hereinafter, a projection type image display device according to the present invention will be described in detail with reference to the drawings.

[First Embodiment of Projection Type Image Display Device]
FIG. 1 is a front view showing the configuration of the projection type image display apparatus according to the first embodiment of the present invention.

  As shown in FIG. 1, the projection type image display device according to the present invention is a three-eye projection type image display device having first to third projection units 1, 2, and 3. These projection units 1, 2, and 3 project images of different colors onto the screen 101, and on the screen 101, the images of the respective colors are combined to display a color image.

  Each of these projection units 1, 2, and 3 is disposed at a position where the optical axes are substantially equal to the distance from the optical axes of the other two projection units. That is, the distance a from the pupil position of the first projection unit 1 to the pupil position of the second projection unit 2 and the distance b from the pupil position of the third projection unit 3 are substantially equal, and the second projection unit 2 The distance a from the pupil position of the first projection unit 1 to the pupil position of the first projection unit 1 and the distance c from the pupil position of the third projection unit 3 are substantially equal, and from the pupil position of the third projection unit 3, the first The distance b to the pupil position of the projection unit 1 and the distance c to the pupil position of the second projection unit 2 are substantially equal. Therefore, the projection units 1, 2, and 3 are arranged in a state where each pupil position is located at each vertex of the triangle.

  In addition, for each position of each projection unit 1, 2 and 3, the length of the perpendicular drawn from the pupil position of one projection unit to the line connecting the pupil positions of the other two projection units is It is preferable that the distance is shorter than the distance between the pupil positions of the other two projection units.

  FIG. 2 is a side view showing a configuration of a projection unit constituting the projection type image display device according to the present invention.

  As shown in FIG. 2, the first projection unit 1 is illuminated by the first color light of the three primary colors, for example, a semiconductor light source 4R that emits red (R), and the light from the semiconductor light source 4R. And a projection lens 7R that projects the light reflected by the wire grid reflection type polarizing plate 6R through the spatial light modulation element 5R onto the screen.

  Similarly, as shown in FIG. 2, the second projection unit 2 includes a semiconductor light source 4G that emits light of a second color among the three primary colors, for example, green (G), and light from the semiconductor light source 4G. And a projection lens 7G that projects the light reflected by the wire grid reflection type polarizing plate 6G through the spatial light modulation element 5G onto the screen.

  Similarly, as shown in FIG. 2, the third projection unit 3 includes a semiconductor light source 4B that emits light of a third color among the three primary colors, for example, blue (B), and light from the semiconductor light source 4B. And a projection lens 7B that projects the light reflected by the wire grid reflection type polarizing plate 6B through the spatial light modulation element 5B onto the screen.

  The semiconductor light sources 4R, 4G, and 4B in the projection units 1, 2, and 3 are light sources having a narrow emission wavelength band, such as semiconductor lasers and LEDs, and are preferably LEDs. Moreover, it is desirable that the spatial light modulation elements 5R, 5G, and 5B in the projection units 1, 2, and 3 are reflective spatial light modulation elements.

  In each of the projection units 1, 2, and 3, the illumination light emitted from the semiconductor light sources 4R, 4G, and 4B passes through the illumination optical systems 8R, 8G, and 8B, and is installed to be inclined with respect to the optical axis. (Wire Grid) The light enters the reflective polarizing plates 6R, 6G, and 6B. The illumination optical systems 8R, 8G, and 8B are configured to include an integrator such as a light pipe or a light tunnel, have a function of uniforming the illuminance distribution of illumination light, and a function of aligning the polarization direction. is doing. The light pipes or light tunnels in the illumination optical systems 8R, 8G, and 8B are preferably tapered with a wide opening on the exit side.

  The illumination light incident on the wire grid reflection type polarizing plates 6R, 6G, 6B is converted to P polarization with respect to the wire grid reflection type polarizing plates 6R, 6G, 6B. It passes through 6G and 6B.

  The illumination light transmitted through the wire grid reflection type polarizing plates 6R, 6G, and 6B is incident on a field lens (not shown), and the principal ray is converted into illumination light that is nearly parallel. The illumination light is incident on the spatial light modulation elements 5R, 5G, and 5B, and is polarization-modulated according to the image signal supplied to the spatial light modulation elements 5R, 5G, and 5B. When the spatial light modulators 5R, 5G, and 5B are reflective spatial light modulators, the modulated illumination light is reflected on the pixel electrodes of the spatial light modulators 5R, 5G, and 5B.

  The illumination light that has passed through the spatial light modulators 5R, 5G, and 5B, that is, the modulated light is incident again on the field lens, converged toward the pupil position of the projection lenses 7R, 7G, and 7B, and is reflected by the wire grid reflective polarizing plate 6R. , 6G, 6B. In the wire grid reflective polarizing plates 6R, 6G, 6B, the modulated light is S-polarized with respect to the wire grid reflective polarizing plates 6R, 6G, 6B. Reflected by 6B and directed toward the projection lenses 7R, 7G, and 7B.

  The modulated light incident on the projection lenses 7R, 7G, and 7B is imaged on the screen 101 by the projection lenses 7R, 7G, and 7B.

  In this projection type image display apparatus, in order to synthesize a display image on the screen 101, each projection unit 1, 2, 3 is arranged, and each projection unit 1, 2, 3 corresponds to a predetermined projection distance. Then, the spatial light modulation elements 5R, 5G, and 5B are shifted and adjusted. The predetermined projection distance is desirably the shortest projection distance in the projection type image display apparatus.

  Next, in order to correct the magnification error of the projection lenses 7R, 7G, and 7B of the projection units 1, 2, and 3, the focal length fine adjustment mechanism provided in each projection lens 7R, 7G, and 7B or the projection The projection magnification is adjusted by moving the entire lenses 7R, 7G, and 7B back and forth. Therefore, it is desirable to provide a focal length fine adjustment mechanism for the projection lenses 7R, 7G, and 7B.

  Furthermore, image synthesis is performed on the screen 101 by shifting and adjusting the entire projection units 1, 2, 3 in accordance with the required projection distance. Therefore, it is desirable that each projection unit 1, 2, 3 is supported by an adjustment mechanism for performing image composition on the screen 101 in accordance with the projection distance. At this time, focusing adjustment is performed by adjusting a focus mechanism provided in the projection lenses 7R, 7G, and 7B.

  In this way, the images displayed by the projection units 1, 2 and 3 are combined on the screen 101.

  In this projection type image display device, the projection lens 7R of the first projection unit 1 has a shape in which the portions on the second and third projection units 2 and 3 side are linearly cut, and the second The projection lens 7G of the projection unit 2 has a shape in which the first and third projection units 1 and 3 side portions are linearly cut, and the projection lens 7B of the third projection unit 3 is the first and first projections. The distance between the projection lenses 7R, 7G, and 7B (distance between the axes) can be further shortened by setting the portion of the projection unit 1 and 2 on the side of 2 to be linearly cut.

[Second Embodiment of Projection Type Image Display Device]
FIG. 3 is a side view showing the configuration of the projection type image display apparatus according to the second embodiment of the present invention.

  As shown in FIG. 3, the projection type image display apparatus in this embodiment reflects the light projected by each projection unit 1, 2, 3 in the projection type image display apparatus in the first embodiment described above. The aspherical reflecting mirror 9 that leads to the screen 101 is provided. The configuration of each projection unit 1, 2, 3 is the same as that in the first embodiment. However, in this projection type image display device, the projection lenses 7R, 7G, and 7B in the projection units 1, 2, and 3 have aspherical lenses that compensate for image distortion generated in the aspherical reflecting mirror 9. Yes. The correction of the image distortion in the projection lenses 7R, 7G, and 7B is optimized for each color of the modulated light projected by the projection units 1, 2, and 3.

  In this projection type image display device, the modulated light emitted from the projection lenses 7 R, 7 G, 7 B of the projection units 1, 2, 3 is incident on the aspheric reflecting mirror 9 and reflected by the aspheric reflecting mirror 9. As a result, the image is synthesized on the screen 101. The aspheric reflecting mirror 9 may be a convex mirror or a concave mirror.

  On the surface of the aspherical reflecting mirror 9, the modulated light from each of the projection units 1, 2, and 3 has different reflection positions and therefore has different incident angles. Therefore, for example, with respect to the aspherical reflecting mirror 9 optimized for the second projection unit 2, image distortion occurs in the modulated light from the other first and third projection units 1 and 3. . Therefore, the aspherical lenses included in the projection lenses 7R and 7B of the first and third projection units 1 and 3 are optimized to correct distortion aberration different from that of the second projection unit 2. Yes.

  Also in this projection type image display device, in order to synthesize a display image on the screen 101, the projection units 1, 2, 3 and the aspherical reflecting mirror 9 are arranged. The spatial light modulators 5R, 5G, and 5B are shift-adjusted corresponding to a predetermined projection distance. The predetermined projection distance is desirably the shortest projection distance in the projection type image display apparatus.

  Next, in order to correct the magnification error of the projection lenses 7R, 7G, and 7B of the projection units 1, 2, and 3, the focal length fine adjustment mechanism provided in each projection lens 7R, 7G, and 7B or the projection The projection magnification is adjusted by moving the entire lenses 7R, 7G, and 7B back and forth. Therefore, it is desirable to provide a focal length fine adjustment mechanism for the projection lenses 7R, 7G, and 7B.

  Furthermore, image synthesis is performed on the screen 101 by shifting and adjusting the entire projection units 1, 2, 3 in accordance with the required projection distance. Therefore, it is desirable that each projection unit 1, 2, 3 is supported by an adjustment mechanism for performing image composition on the screen 101 in accordance with the projection distance. At this time, focusing adjustment is performed by adjusting a focus mechanism provided in the projection lenses 7R, 7G, and 7B.

  In this way, the images displayed by the projection units 1, 2 and 3 are combined on the screen 101.

[Third Embodiment of Projection Type Image Display Device]
FIG. 4 is a side view showing the configuration of the projection type image display apparatus according to the third embodiment of the present invention.

  The projection type image display apparatus according to this embodiment is the same as the projection type image display apparatus according to the first embodiment described above, as shown in FIG. 7B has a bent structure of the optical axis, and is provided with a reflecting mirror 9 that reflects the light projected by these projection units 1, 2, and 3 and guides it to the screen 101.

  The configurations of the projection units 1, 2, and 3 are the same as those in the first embodiment described above except for the projection lenses 7R, 7G, and 7B. In this projection type image display apparatus, the projection lenses 7R, 7G, and 7B in the projection units 1, 2, and 3 are folded in the lens barrel and are made of a mirror, a prism, or the like for bending the optical axis. It has a curved structure. The modulated light incident on the projection lenses 7R, 7G, and 7B is bent and emitted by a predetermined angle determined for each of the projection lenses 7R, 7G, and 7B so as to be combined on the screen 101. .

  Each of the projection lenses 7R, 7G, and 7B includes an aspheric lens that compensates for image distortion according to a difference in relative position with respect to the screen 101 and a difference in incident angle of modulated light with respect to the screen 101. That is, the correction of the image distortion in the projection lenses 7R, 7G, and 7B is optimized for each color of the modulated light projected by the projection units 1, 2, and 3.

  In this projection type image display device, the modulated light that is bent and emitted from the projection lenses 7 R, 7 G, and 7 B of the projection units 1, 2, and 3 enters the reflecting mirror 9 and is reflected by the reflecting mirror 9. As a result, the image is synthesized on the screen 101. The reflecting mirror 9 may be an aspherical convex mirror or concave mirror.

  In the screen 101, the modulated light from the projection units 1, 2, and 3 has different incident angles because the relative positions of the screen 101 and the projection units 1, 2, and 3 are different. Therefore, for example, with respect to a display image optimized for the second projection unit 2, image distortion occurs in the modulated light from the other first and third projection units 1 and 3. Therefore, the aspherical lenses included in the projection lenses 7R and 7B of the first and third projection units 1 and 3 are optimized to correct distortion aberration different from that of the second projection unit 2. Yes.

  Also in this projection type image display apparatus, in order to synthesize a display image on the screen 101, the projection units 1, 2, 3 and the reflecting mirror 9 are arranged. The spatial light modulation elements 5R, 5G, and 5B are shift-adjusted in accordance with the projection distance. The predetermined projection distance is desirably the shortest projection distance in the projection type image display apparatus.

  Next, in order to correct the magnification error of the projection lenses 7R, 7G, and 7B of the projection units 1, 2, and 3, the focal length fine adjustment mechanism provided in each projection lens 7R, 7G, and 7B or the projection The projection magnification is adjusted by moving the entire lenses 7R, 7G, and 7B. Therefore, it is desirable to provide a focal length fine adjustment mechanism for the projection lenses 7R, 7G, and 7B.

  Furthermore, image synthesis is performed on the screen 101 by shifting and adjusting the entire projection units 1, 2, 3 in accordance with the required projection distance. Therefore, it is desirable that each projection unit 1, 2, 3 is supported by an adjustment mechanism for performing image composition on the screen 101 in accordance with the projection distance. At this time, focusing adjustment is performed by adjusting a focus mechanism provided in the projection lenses 7R, 7G, and 7B.

  In this way, the images displayed by the projection units 1, 2 and 3 are combined on the screen 101.

It is a front view which shows the structure in 1st Embodiment of the projection type image display apparatus which concerns on this invention. It is a side view which shows the structure of the projection unit which comprises the said projection type image display apparatus. It is a side view which shows the structure in 2nd Embodiment of the projection type image display apparatus which concerns on this invention. It is a side view which shows the structure in 3rd Embodiment of the projection type image display apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st projection unit 2 2nd projection unit 3 3rd projection unit 4R Semiconductor light source (R)
4G Semiconductor light source (G)
4B Semiconductor light source (B)
5R Spatial modulation element (R)
5G Spatial Modulator (G)
5B Spatial modulation element (B)
6R Wire grid reflective polarizing plate (R)
6G Wire grid reflection type polarizing plate (G)
6B Wire grid reflection type polarizing plate (B)
7R Projection lens (R)
7G projection lens (G)
7B Projection lens (B)
9 Aspherical reflectors, reflectors

Claims (5)

A first semiconductor light source that emits light of the first color among the three primary colors, a first spatial light modulator that is illuminated by light from the first semiconductor light source, and the first spatial light modulator A first projection unit having a first projection lens that projects the light reflected by the first wire grid reflective polarizing plate through the screen onto the screen;
A second semiconductor light source that emits light of the second color among the three primary colors, a second spatial light modulator that is illuminated by light from the second semiconductor light source, and the second spatial light modulator A second projection unit having a second projection lens that projects the light reflected by the second wire grid reflective polarizing plate through the screen onto the screen;
A third semiconductor light source that emits light of the third color among the three primary colors, a third spatial light modulator that is illuminated by light from the third semiconductor light source, and the third spatial light modulator A third projection unit having a third projection lens for projecting the light reflected by the third wire grid reflective polarizer through the screen onto the screen,
Each of the projection units is disposed at a position where each optical axis is a distance that is substantially equal to the optical axis of the other two projection units, and a color image is obtained by combining the images of the respective colors on the screen. Projection type image display device characterized by displaying. An aspheric reflector that reflects the light projected by each projection unit and guides it to the screen;
The projection type image display apparatus according to claim 1, wherein the projection lens in each projection unit includes an aspheric lens that compensates for image distortion generated in the aspheric reflecting mirror. The projection lens in each projection unit has a bending structure that bends the optical axis,
2. The projection type according to claim 1, wherein each projection lens has an aspheric lens that compensates for image distortion caused by a difference in relative position with respect to the screen, and has different angles for bending the optical axis. Image display device. 4. The projection type image display device according to claim 1, wherein the semiconductor light source in each projection unit is an LED. 5. The projection type image display device according to any one of claims 1 to 4, wherein the spatial light modulation element in each projection unit is a reflective spatial light modulation element.

Images