JP2009109878A - Image projection device and stereoscopic image projection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image projection device and a stereoscopic image projection system capable of synthesizing and projecting image readout light beams from four image display elements and capable of making short and uniform a distance from the four image display elements to a projection lens. <P>SOLUTION: A PBS 5 outputs in the same direction a green image readout light beam and a red image readout light beam incident from different directions. A PBS 8 outputs in the same direction a green image readout light beam and a blue image readout light beam incident from the different direction. A PBS 11 outputs in the same direction the green image readout light beam and the red image readout light beam from the PBS 5 and the green image readout light beam and the blue image readout light beam from the PBS 8 incident from the different directions. A projection lens 12 synthesizes the two green image readout light beams, the red image readout light beam and the blue image readout light beam output from the PBS 11 and projects the light beam. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a video projection apparatus that synthesizes and projects video readout light output from a plurality of video display elements, and a stereoscopic video projection system including the same.

  In recent years, high-definition video technology with a sense of reality has rapidly spread, and ultra-high-definition video display exceeding high-vision is being realized. At present, as a high-definition image display method, a method of projecting two green images with high human visibility and synthesizing the images by shifting the two green images by half a pixel in an oblique direction is effective. In the future, it is expected that ultra-high-definition video technology will become increasingly popular as a realistic video technology in the future, and that new 3D video technology will be realized.

A conventional pixel shifting method is disclosed in Patent Document 1, for example. In Patent Document 1, a pixel shifting method in which the polarization direction of light is aligned is devised, and application to binocular stereoscopic display is possible. In addition, Patent Documents 2 and 3 disclose other high-definition video display techniques using pixel shifting.
JP 2004-226767 A JP 2003-322908 A JP 2003-322854 A

  In any of Patent Documents 1, 2, and 3, a method of projecting an image using two image projection apparatuses (liquid crystal projector apparatus or the like) is disclosed. However, since the video display element has a fine pixel structure, in the method of projecting video using two video projectors, the video projected on the screen can be synthesized with a half-pixel shift with high accuracy, or multiple video There is a problem that the operation of adjusting the registration between display elements is very complicated.

  Further, in Patent Document 2, a total of four video display elements including two green video display elements, one red video display element, and one blue video display element are provided in one video projection device, and each video display is provided. A method of synthesizing and projecting image readout light from an element is also disclosed. If the optical system may be complicated, various methods are conceivable as methods for synthesizing and projecting image readout light from the four image display elements. However, the video projection apparatus has a constraint that the distance (optical path length) from the video display element to the projection lens must be shortened. If this distance is long, a projection lens with a long back focus is required, and the design and manufacture of the lens becomes extremely difficult, and even if it can be manufactured, it becomes a very expensive lens.

  For this reason, the number of optical elements such as dichroic mirrors and prisms inserted in the optical path from the video display element to the projection lens needs to be approximately two or less for each video display element. Furthermore, unless each optical component is arranged so that the distance between each image display element and the projection lens is uniform, high-quality image display cannot be realized. The method disclosed in Patent Document 2 has a problem that the distance from each image display element to the projection lens is long and non-uniform.

  The present invention has been made in view of the above-described problems, and can synthesize and project the image readout light from the four image display elements, and the distance from the four image display elements to the projection lens. An object of the present invention is to provide a video projection apparatus and a stereoscopic video projection system that can shorten and make the image length uniform.

  The present invention has been made to solve the above-described problem, and includes a first video display element that outputs a first color video readout light, and a second color output that outputs a second color video readout light. The image display element, the third image display element that outputs the image reading light of the third color, and the fourth image display element that outputs the image reading light of the fourth color, and the first image incident from different directions. A first optical element that outputs the image reading light of one color and the image reading light of the second color in the same direction; the image reading light of the third color and the fourth color incident from different directions; A second optical element that outputs the first image reading light in the same direction, and the first color image reading light and the second color image reading light from the first optical element that are incident from different directions. And projection of the third color from the second optical element. A third optical element that outputs readout light and the fourth color image readout light in the same direction, and the first color image readout light and the second color output from the third optical element An image projection apparatus comprising: a color image readout light, a third color image readout light, and a projection lens that combines and projects the fourth color image readout light.

  Further, in the video projection apparatus (FIGS. 1, 3, 6, 8, 10, and 12) of the present invention, the first video display element, the second video display element, and the third video. The display element and the fourth image display element are reflective image display elements, and the first optical element further separates the first color light and the second color light incident from the same direction. The first color light is incident on the first video display element, and the second color light is incident on the second video display element, and the second optical element is further identical. The third color light and the fourth color light incident from the direction are separated, the third color light is incident on the third image display element, and the fourth color light is incident on the third color display element. It is made to enter into a 4th image display element.

  In addition, the video projection device (FIGS. 3 and 10) of the present invention includes a white light source, and the first color light, the second color light, and the third color among the light from the white light source. And the light of the fourth color are separated, the light of the first color and the light of the second color are incident on the first optical element, and the light of the third color and the light of the third color are incident on the first optical element. And a fourth optical element that makes the fourth color light incident on the second optical element.

  In addition, the video projection device (FIGS. 6 and 12) of the present invention includes a first light source that outputs the first color light and the second color light incident on the first optical element; And a second light source that outputs the third color light and the fourth color light incident on the second optical element.

  Further, in the video projection apparatus (FIGS. 2, 5, 7, 9, 11, and 13) of the present invention, the first video display element, the second video display element, and the third video. The display element and the fourth image display element are transmissive image display elements.

  Moreover, the video projection apparatus (FIGS. 5 and 11) of the present invention includes a white light source, light of the first color, light of the second color, and light of the third color among the light from the white light source, and A fourth optical element that separates light of a fourth color, and the first color light separated by the fourth optical element is incident on the first video display element, and A first optical element group for making the second color light separated by the optical element incident on the second video display element; and the third color light separated by the fourth optical element. A second optical element group that is incident on the third video display element and that causes the fourth color light separated by the fourth optical element to be incident on the fourth video display element. It is characterized by that.

  In addition, the video projection device according to the present invention (FIGS. 7 and 13) includes a first light source that generates light of a first color incident on the first video display element, and a second video display element. A second light source that generates incident second color light, a third light source that generates third color light incident on the third image display element, and a fourth image display element And a fourth light source for generating incident fourth color light.

  In the video projection device of the present invention, the first video display element and the second video display element, or the third video display element and the fourth video display element may emit green video readout light. A green image display element for output, wherein the green image read light from each of the green image display elements is shifted by a half pixel on the projected image.

  According to another aspect of the present invention, there is provided a stereoscopic video projection system comprising: the video projection device described above; and a lens array including a plurality of minute lenses on which video readout light projected by the video projection device is incident. .

  According to the present invention, by providing the first optical element, the second optical element, the third optical element, and the projection lens, the image readout light from the four image display elements is synthesized and projected. Can do.

  According to the present invention, the number of optical elements inserted on the optical path from the image display element to the projection lens is the first optical element and the third optical element for the first color and the second color. The third color and the fourth color are the second optical element and the third optical element, and therefore the distance from the four image display elements to the projection lens is shortened. It can be made uniform.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
First, a first embodiment of the present invention will be described. FIG. 1 shows the configuration of the video projection apparatus according to the present embodiment. The video projection apparatus shown in FIG. 1 has a first green video display element 1a, a second green video display element 2a, a red video display element 3a, and a blue video display element 4a as video display elements that output video readout light. have. 1 includes PBSs (polarization beam splitters) 5 and 8, phase conversion filters 6 and 9, polarizers 7 and 10, and a projection lens 12 as other optical elements.

  In the present embodiment and the subsequent embodiments, as shown in FIG. 15, the two green image display elements include a pixel 151 on the projection image by the first green image reading light and a second green image reading light. The arrangement position is adjusted so that the pixel 152 on the projected image is shifted by a half pixel in the diagonal direction (shifted by a half pixel in the vertical and horizontal directions). As a result, it is possible to realize high-definition video display by pixel shifting.

  Here, liquid crystal on silicon (LCOS), digital optical processing (DLP), or the like can be used for the green image display element. The PBS may have any transmission / reflection characteristics corresponding to the polarization of light. For example, a prism-shaped polarization beam splitter, a wire grid that is a metal sub-wavelength optical element, or the like can be used. In particular, in the case of a wire grid, there is an advantage that the light receiving angle is large, the collection rate of light from the light source is large, and the polarized light is completely separated, so that the P polarized light is transmitted with high efficiency. The conventional MacNeill type glass polarizer exhibits birefringence due to the heat and stress of the lamp, but the wire grid is characterized by high durability such as heat of the lamp and wide wavelength band characteristics.

  Moreover, since the aberration according to the reflectance of S-polarized light is caused by incidence from the aluminum wire grid deposition surface and incidence from the substrate glass as the back surface, the image readout light is filtered by a linear polarizing plate. High-contrast video readout is also possible by making it incident at. Alternatively, bonding a wire grid to the prism and adjusting the incident angle to the wire grid interface and the incident angle from the back surface to the same level is also effective for high-quality video readout.

  The first green image display element 1a and the red image display element 3a are arranged facing the PBS 5 (first optical element). Each video display element is a reflective video display element that reflects incident light and outputs it as video readout light. As light for reading out images from the first green image display element 1a and the red image display element 3a, green light and red light which are P-polarized light and S-polarized light respectively enter the PBS 5 from the same direction. Of course, the position of the image display element and the polarization direction of light may be reversed with respect to green light and red light.

  Green light is transmitted through the PBS 5 and red light is reflected by the PBS 5. Thereby, the green light and the red light are separated, the green light is incident on the first green image display element 1a, and the red light is incident on the red image display element 3a. Each light is reflected by the image display element, the polarization direction changes by 90 degrees, and again enters the PBS 5 as S-polarized green image readout light and P-polarized red image readout light. The green image readout light is reflected by the PBS 5, and the red image readout light passes through the PBS 5 and is output as green-red composite light.

  The combined green-red light output from the PBS 5 enters the phase conversion filter 6. This phase conversion filter 6 changes the polarization direction of light only in a specific wavelength region and does not change the polarization direction of light in other wavelength regions. In particular, only the light in the red wavelength band is selectively changed in polarization direction. It is changed by 90 degrees to align the polarization directions of green light and red light. After passing through the phase conversion filter 6, the green-red composite light becomes a light whose polarization is aligned with S polarization. Subsequently, this light passes through the polarizer 7. By transmitting the light through the polarizer 7, it is possible to prevent a decrease in contrast due to the influence of the extinction ratio of the reflection / transmission characteristics of the PBS 5 and to obtain a high-contrast image.

  As described above, the first green image readout light and the red image readout light are combined. Similarly, the second green image readout light and the blue image readout light are combined as follows. . The second green image display element 2a and the blue image display element 4a are arranged facing the PBS 8 (second optical element). Each image display element is a reflective image display element. As light for reading images from the second green image display element 2a and the blue image display element 4a, green light and blue light that are S-polarized light and P-polarized light respectively enter the PBS 8 from the same direction. Of course, the position of the image display element and the polarization direction of light may be reversed with respect to green light and blue light.

  Green light is reflected by the PBS 8 and blue light is transmitted through the PBS 8. Thereby, the green light and the blue light are separated, the green light is incident on the second green image display element 2a, and the blue light is incident on the blue image display element 4a. Each light is reflected by the image display element, the polarization direction changes by 90 degrees, and again enters the PBS 8 as P-polarized green image readout light and S-polarized blue image readout light. The green image readout light is transmitted through the PBS 8 and the blue image readout light is reflected by the PBS 8 and output as green-blue combined light.

  The green-blue synthesized light output from the PBS 8 enters the phase conversion filter 9. The phase conversion filter 9 selectively changes only the light in the blue wavelength band by 90 degrees and aligns the polarization directions of the green light and the blue light. After passing through the phase conversion filter 9, the green-blue combined light becomes light whose polarization is aligned with P-polarization. Subsequently, this light passes through the polarizer 10. By transmitting the polarizer 10, the contrast is prevented from being lowered due to the extinction ratio of the reflection / transmission characteristics of the PBS 8, and a high-contrast image can be obtained.

  The green-red composite light and the green-blue composite light are incident on the PBS 11 (third optical element). The green-red composite light is reflected by the PBS 11, and the green-blue composite light passes through the PBS 11, so that image readout light obtained by combining both is output from the PBS 11 and enters the projection lens 12. The projection lens 12 displays an image by projecting light obtained by synthesizing four image readout lights onto a screen or the like (not shown).

  As described above, according to the present embodiment, PBSs 5 and 8 that separate and synthesize light based on transmission / reflection characteristics according to the polarization of light, and the combined light from PBSs 5 and 8 are combined to the projection lens 12. By providing the PBS 11 for output, it is possible to synthesize and project the video readout light from the four video display elements. The number of optical elements inserted on the optical path from the image display element to the projection lens is two PBS5 and 11 for the first green and red, and PBS8 and 11 for the second green and blue. Therefore, the distance from the four image display elements to the projection lens 12 can be made short and uniform.

  As described above, there is a conventional technique for projecting an image using two image projection devices. On the other hand, by enabling image projection by one image projection device as in this embodiment, The effects described below can be obtained. In an image projection apparatus using a high-intensity lamp, optical components such as a prism and a lens become high temperature due to the influence of heat, and optical characteristics such as birefringence characteristics change. Furthermore, the projection image fluctuates with time because a table or the like that supports the optical block in the casing expands and contracts due to heat.

  Since multiple cases projected by the same video projection device have the same housing and projection lens, the relative variation factors are small, and even if the temperature changes over time, the multiple images The relative registration gap between them is not large. However, since a housing | casing, a projection lens, etc. differ between the some image | videos projected by different image | video projection apparatuses, the big registration shift which cannot be disregarded with the temperature change with progress of time arises. In the present embodiment, it is possible to synthesize video readout light from four video display elements in one video projection device and project the video readout light with a single projection lens. Can suppress the temporal change in registration shift between images, and can maintain the pixel shift accuracy with higher accuracy.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. FIG. 2 shows the configuration of the video projection apparatus according to the present embodiment. Below, it demonstrates centering on the difference with 1st Embodiment (FIG. 1). In the first embodiment, a reflective image display element is used. However, in this embodiment, a transmissive image display element that transmits incident light and outputs it as image readout light (first green image display element 1b). The second green image display element 2b, the red image display element 3b, and the blue image display element 4b) are used.

  Light incident from the back of each video display element passes through each video display element and is output as video readout light. The method of combining the respective image readout lights and projecting them by the projection lens 12 is the same as that in the first embodiment, and thus the description thereof is omitted.

  When a transmissive image display element is used, a phase conversion filter that changes the phase by 90 degrees is inserted on the output side of the red image display element 3b, thereby transmitting red light and reflecting green light instead of PBS5. A characteristic dichroic mirror or prism can also be used. When a dichroic prism or mirror is used, the phase conversion filter 6 is eliminated by setting the polarization direction of the red image readout light from the red image display element to S polarization and aligning the polarization directions of the green and red image readout light. You can also.

  Similarly, when a transmission type image display element is used, by inserting a phase conversion filter that changes the phase by 90 degrees on the output side of the blue image display element 4b, the green light is transmitted instead of the PBS8. It is also possible to use a dichroic mirror or prism that reflects the light. When a dichroic prism or mirror is used, the phase conversion filter 9 is eliminated by setting the polarization direction of the blue image readout light from the blue image display element to P polarization and aligning the polarization directions of the blue and green image readout light. You can also

  According to the present embodiment, similarly to the first embodiment, it is possible to synthesize and project the image readout light from the four image display elements, and the distance from the four image display elements to the projection lens 12. Can be made short and uniform.

(Third embodiment)
Next, a third embodiment of the present invention will be described. FIG. 3 shows the configuration of the video projection apparatus according to the present embodiment. Below, it demonstrates centering on the difference with 1st Embodiment (FIG. 1). In the present embodiment, a reflective video display element (first green video display element 1a, second green video display element 2a, red video display element 3a, blue video display element 4a) is used.

  In FIG. 3, a light source 31 for reading light is provided. The light source 31 is a white light source (such as a halogen lamp or a xenon lamp) generally used in a video projection apparatus. The output light from the light source 31 passes through a polarization conversion element 33 for aligning the polarization direction of the output light through a general illumination optical system 32 that collimates and makes uniform the incident light.

  The white light whose polarization direction is aligned in one direction as described above enters the dichroic mirror 34 (fourth optical element) that separates the input light. FIG. 4 shows an example of the transmittance characteristic of the dichroic mirror 34, where the horizontal axis indicates the wavelength of light and the vertical axis indicates the transmittance. As shown in FIG. 4, the dichroic mirror 34 totally transmits the red band light and transmits about ½ of the green band light among the light having the same polarization direction (S-polarized light), and the remaining approximately Approx. It has a characteristic of reflecting half and totally reflecting light in the blue band. Due to such characteristics, about half of the green light and red light (S-polarized light) are transmitted through the dichroic mirror 34 and output in the direction of the PBS 5, and about half of the green light and blue light (S-polarized light) are transmitted by the dichroic mirror 34. Reflected and output in the direction of PBS8.

  The green light and the red light (S-polarized light) transmitted through the dichroic mirror 34 are transmitted through the phase conversion filter 37 that changes the polarization direction of the light by 90 degrees, and the phase conversion that changes the polarization direction of only the light in the red wavelength band by 90 degrees. The light passes through the filter 35 and enters the PBS 5 as green light (P-polarized light) and red light (S-polarized light) having polarization directions different from each other by 90 degrees. Alternatively, green light and red light (S-polarized light) that have passed through the dichroic mirror 34 are transmitted through a phase conversion filter that converts the phase of only the green wavelength light by 90, and red light is converted to S-polarized light and green light is converted to P-polarized light. Also good. On the other hand, green light and blue light (S-polarized light) reflected by the dichroic mirror 34 are transmitted through the phase conversion filter 36 that changes the polarization direction by 90 degrees only for the light in the blue wavelength band, and the polarization directions are different from each other by 90 degrees. Light (S-polarized light) and blue light (P-polarized light) enter the PBS 8. The method of causing the light incident on the PBSs 5 and 8 to enter each image display element, outputting the image readout light, synthesizing each image readout light, and projecting by the projection lens 12 is the same as in the first embodiment. Is omitted.

  According to the present embodiment, similarly to the first embodiment, it is possible to synthesize and project the image readout light from the four image display elements, and the distance from the four image display elements to the projection lens 12. Can be made short and uniform. In addition, a high-definition video display by pixel shifting can be realized with a compact configuration using a single light source 31. Further, in the present embodiment, a polarizer can be inserted on the optical rear side of the phase conversion filters 35 and 36, which further increases the degree of polarization and is effective in maintaining a high contrast for image readout. is there.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described. FIG. 5 shows the configuration of the video projection apparatus according to the present embodiment. Below, it demonstrates centering on the difference with 3rd Embodiment (FIG. 3). In the present embodiment, transmissive video display elements (first green video display element 1b, second green video display element 2b, red video display element 3b, blue video display element 4b) are used.

  In FIG. 5, in order to make each color light incident on each image display element, a dichroic mirror 51 that transmits green light and reflects red light, a dichroic mirror 52 that transmits blue light and reflects green light, and a total reflection mirror 53, 54, 55, and 56, and phase conversion filters 57 and 58 that change the polarization direction of light by 90 degrees are provided. The green light and red light transmitted through the dichroic mirror 34 enter the dichroic mirror 51. The green light passes through the dichroic mirror 51, and the red light is reflected by the dichroic mirror 51 and enters the red video display element 3b. The green light transmitted through the dichroic mirror 51 is reflected by the total reflection mirrors 53 and 54, passes through the phase conversion filter 57, and enters the first green image display element 1b.

  On the other hand, the green light and the blue light reflected by the dichroic mirror 34 enter the dichroic mirror 52. The green light is reflected by the dichroic mirror 52 and is incident on the second green image display element 2 b, and the blue light is transmitted through the dichroic mirror 52. The blue light transmitted through the dichroic mirror 52 is reflected by the total reflection mirrors 55 and 56, passes through the phase conversion filter 58, and enters the blue image display element 4b. Light incident from the back of each video display element passes through each video display element and is output as video readout light. The method of combining the respective image readout lights and projecting them by the projection lens 12 is the same as that in the first embodiment, and thus the description thereof is omitted.

  According to the present embodiment, similarly to the third embodiment, it is possible to synthesize and project the image readout light from the four image display elements, and the distance from the four image display elements to the projection lens 12. Can be made short and uniform. In addition, a high-definition video display by pixel shifting can be realized with a compact configuration using a single light source 31.

(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described. FIG. 6 shows the configuration of the video projection apparatus according to the present embodiment. Below, it demonstrates centering on the difference with 3rd Embodiment (FIG. 3). In the present embodiment, a reflective video display element (first green video display element 1a, second green video display element 2a, red video display element 3a, blue video display element 4a) is used.

  In FIG. 6, a light source 61 that outputs light in the green and red wavelength bands and a light source 62 that outputs light in the green and blue wavelength bands are provided. As these light sources, a single LED or a plurality of LEDs arranged in an array can be used. The light output from the light source 61 is collimated and uniformed, passes through the polarization conversion element 63, and after the polarization direction is aligned in a certain direction, only the light in the red wavelength band is converted by 90 degrees. The light passes through the phase conversion filter 64 and enters the PBS 5 as green light (P-polarized light) and red light (S-polarized light) having polarization directions different from each other by 90 degrees.

  On the other hand, the light output from the light source 62 is collimated and uniformed, passes through the polarization conversion element 65, and after the polarization direction is aligned in a certain direction, only the light in the blue wavelength band is polarized by 90 degrees. The light passes through the phase conversion filter 66 to be converted, and enters the PBS 8 as green light (S-polarized light) and blue light (P-polarized light) having polarization directions different from each other by 90 degrees. The method of causing the light incident on the PBSs 5 and 8 to enter each image display element, outputting the image readout light, synthesizing each image readout light, and projecting by the projection lens 12 is the same as in the first embodiment. Is omitted.

  According to the present embodiment, similarly to the first embodiment, it is possible to synthesize and project the image readout light from the four image display elements, and the distance from the four image display elements to the projection lens 12. Can be made short and uniform. Moreover, the effect demonstrated below is also acquired.

  A halogen lamp or a xenon lamp used as a light source of an image projection apparatus has a lamp house, a reflecting mirror, and the like, and thus is relatively large and has a large power source. In addition, since these light sources are white point light sources, the optical system (illumination optical system 32 in FIG. 5) that generates illumination light that spreads light and has excellent uniformity and parallelism requires a long optical path length. Generally, it occupies a large part of the optical system of the entire image projection apparatus. Further, in order to divide the white light into light of each color, as shown in FIG. 5, a large number of optical components such as a dichroic mirror and a half mirror are required between the light source and the image display element.

  On the other hand, when an LED light source is used, it is possible to use illumination in which a plurality of minute LEDs are arranged in an array, so that only the light from the LED light source can be passed through an integrator to cover the entire image display element. Illumination light can be generated relatively easily. Further, since a lamp house or the like is not required and the LED is arrayed is a thin surface light source, the light source can be reduced in size as compared with the third embodiment. Further, when using an LED light source, the output wavelength can be selected for each LED element. For example, in FIG. 6, a green and red LED array is used as the light source 61 and a green and blue LED array is used as the light source 62. be able to.

  In addition, since the phase conversion filter 64 and the PBS 5 (or the phase conversion filter 66 and the PBS 8) in FIG. 6 can separate and synthesize light using polarized light, a large number of optical elements are used to separate light of each color. The image projection apparatus can be reduced in size without using an element.

(Sixth embodiment)
Next, a sixth embodiment of the present invention will be described. FIG. 7 shows the configuration of the video projection apparatus according to the present embodiment. Below, it demonstrates centering on the difference with 5th Embodiment (FIG. 6). In the present embodiment, transmissive video display elements (first green video display element 1b, second green video display element 2b, red video display element 3b, blue video display element 4b) are used.

  In FIG. 7, light sources 71 and 72 that output green light, a light source 73 that outputs red light, and a light source 74 that outputs blue light are provided. In addition, polarization conversion elements 75, 76, 77, 78 for aligning the polarization direction of the output light are provided.

  The light output from the light source 71 is transmitted through the polarization conversion element 75 and is incident on the first green image display element 1b after the polarization direction is aligned in a certain direction. The light output from the light source 72 is transmitted through the polarization conversion element 76 and is incident on the second green image display element 2b after the polarization direction is aligned in a certain direction. The light output from the light source 73 is transmitted through the polarization conversion element 77 and is incident on the red image display element 3b after the polarization direction is aligned in a certain direction. The light output from the light source 74 is transmitted through the polarization conversion element 78 and is incident on the blue image display element 4b after the polarization direction is aligned in a certain direction.

  Light incident from the back of each video display element passes through each video display element and is output as video readout light. The method of combining the respective image readout lights and projecting them by the projection lens 12 is the same as that in the first embodiment, and thus the description thereof is omitted.

  According to the present embodiment, similarly to the fifth embodiment, it is possible to synthesize and project the image readout light from the four image display elements, and the distance from the four image display elements to the projection lens 12. Can be made short and uniform. Further, by using an LED light source as the light sources 71, 72, 73, 74, the light source can be miniaturized as in the fifth embodiment. Further, the image projection apparatus can be miniaturized without using a large number of optical elements to separate the light of each color.

(Seventh embodiment)
Next, a seventh embodiment of the present invention will be described. FIG. 8 shows the configuration of the video projection apparatus according to the present embodiment. Below, it demonstrates centering on the difference with 1st Embodiment (FIG. 1). In the present embodiment, a reflective video display element (first green video display element 1a, second green video display element 2a, red video display element 3a, blue video display element 4a) is used.

  In FIG. 8, the first green video display element 1a and the second green video display element 2a are arranged facing the PBS 8, and the red video display element 3a and the blue video display element 4a are arranged facing the PBS 5. Has been. Further, a polarization dichroic prism 81 is provided instead of the PBS 11.

  As light for reading out images from the red image display element 3a and the blue image display element 4a, red light and blue light which are S-polarized light and P-polarized light respectively enter the PBS 5 from the same direction. The red light is reflected by the PBS 5 and the blue light is transmitted through the PBS 5. As a result, the red light and the blue light are separated, the red light is incident on the red video display element 3a, and the blue light is incident on the blue video display element 4a. Each light is reflected by the image display element, the polarization direction is changed by 90 degrees, and again enters the PBS 5 as red image read light that is P-polarized light and blue image read light that is S-polarized light.

  The red image readout light is transmitted through the PBS 5 and the blue image readout light is reflected by the PBS 5 and output as red-blue combined light. The red-blue combined light output from the PBS 5 is incident on the phase conversion filter 6, and after the polarized light is aligned with S-polarized light, the light passes through the polarizer 7 and enters the polarization dichroic prism 81.

  On the other hand, two types of green light, S-polarized light and P-polarized light, enter the PBS 8 from the same direction as light for reading out images from the first green image display element 1a and the second green image display element 2a. The S-polarized green light is reflected by the PBS 8, and the P-polarized green light is transmitted through the PBS 8. As a result, two types of green light are separated, S-polarized green light is incident on the first green image display element 1a, and P-polarized green light is incident on the second green image display element 2a. Each light is reflected by the image display element, the polarization direction changes by 90 degrees, and again enters the PBS 8 as green image readout light.

  The P-polarized green image reading light is transmitted through the PBS 8, and the S-polarized green image reading light is reflected by the PBS 8 and output as green combined light. The combined green light output from the PBS 8 is incident on the polarization dichroic prism 81.

  The red-blue combined light is reflected by the polarization dichroic prism 81, and the green combined light passes through the polarization dichroic prism 81, so that image readout light obtained by combining both is output from the polarization dichroic prism 81 and enters the projection lens 12. The projection lens 12 displays an image by projecting light obtained by synthesizing four image readout lights onto a screen or the like (not shown).

  According to the present embodiment, similarly to the first embodiment, it is possible to synthesize and project the image readout light from the four image display elements, and the distance from the four image display elements to the projection lens 12. Can be made short and uniform. In addition, since the first green image display element 1a and the second green image display element 2a are arranged facing the same PBS 8, high-definition image display by high-precision pixel shifting with less change over time. Can be realized.

(Eighth embodiment)
Next, an eighth embodiment of the present invention will be described. FIG. 9 shows the configuration of the video projection apparatus according to the present embodiment. Below, it demonstrates centering on the difference with 7th Embodiment (FIG. 8). In the present embodiment, transmissive video display elements (first green video display element 1b, second green video display element 2b, red video display element 3b, blue video display element 4b) are used.

  Light incident from the back of each video display element passes through each video display element and is output as video readout light. The method of synthesizing each video readout light and projecting it by the projection lens 12 is the same as that of the seventh embodiment, so that the description is omitted.

  According to the present embodiment, similarly to the seventh embodiment, it is possible to synthesize and project the image readout light from the four image display elements, and the distance from the four image display elements to the projection lens 12. Can be made short and uniform. Similarly to the seventh embodiment, since the first green image display element 1a and the second green image display element 2a are arranged facing the same PBS 8, high accuracy with less change with time is obtained. High-definition video display by shifting pixels can be realized.

(Ninth embodiment)
Next, a ninth embodiment of the present invention will be described. FIG. 10 shows the configuration of the video projection apparatus according to the present embodiment. Below, it demonstrates centering on the difference with 7th Embodiment (FIG. 8). In the present embodiment, a reflective video display element (first green video display element 1a, second green video display element 2a, red video display element 3a, blue video display element 4a) is used.

  In FIG. 10, a light source 101 for reading light is provided. The light source 101 is a white light source (such as a halogen lamp or a xenon lamp) generally used in a video projection apparatus. The output light from the light source 101 passes through a polarization conversion element 103 for aligning the polarization direction of the output light through a general illumination optical system 102 that collimates and makes uniform the incident light.

  The white light whose polarization direction is aligned in one direction as described above is incident on the dichroic mirror 104 having a characteristic of reflecting light in the red and blue wavelength bands and transmitting light in the green wavelength band. The red light and blue light reflected by the dichroic mirror 104 pass through the phase conversion filter 105 that converts the polarization direction by 90 degrees only for the light in the red wavelength band, and enter the PBS 5. On the other hand, the green light that has passed through the dichroic mirror 104 passes through the phase conversion filter 106 that converts the polarization direction of about half of the light in the green wavelength band by 90 degrees and enters the PBS 8. Alternatively, when the polarization direction of the light output through the illumination optical system 102 is completely random, the polarization conversion element 103 is used as a phase that converts the polarization direction by 90 degrees only for the light in the red wavelength band with the dichroic mirror 104. If arranged between the conversion filter 105 and the conversion filter 105, the phase conversion filter 106 for converting the polarization direction of about half of the light in the green wavelength band by 90 degrees can be omitted. The method of causing the light incident on the PBSs 5 and 8 to enter each image display element to output the image readout light, synthesize the image readout light, and project the light by the projection lens 12 is the same as in the seventh embodiment. Is omitted.

  According to the present embodiment, similarly to the seventh embodiment, it is possible to synthesize and project the image readout light from the four image display elements, and the distance from the four image display elements to the projection lens 12. Can be made short and uniform. In addition, high-definition video display by pixel shift can be realized with a compact configuration using a single light source 101. Similarly to the seventh embodiment, since the first green image display element 1a and the second green image display element 2a are arranged facing the same PBS 8, high accuracy with less change with time is obtained. High-definition video display by shifting pixels can be realized.

(Tenth embodiment)
Next, a tenth embodiment of the present invention will be described. FIG. 11 shows the configuration of the video projection apparatus according to the present embodiment. Below, it demonstrates centering on the difference with 9th Embodiment (FIG. 10). In the present embodiment, transmissive video display elements (first green video display element 1b, second green video display element 2b, red video display element 3b, blue video display element 4b) are used.

  In FIG. 11, in order to make each color light incident on each image display element, a dichroic mirror 111 that reflects blue light and transmits red light, a transflective mirror 112 that divides green light, a total reflection mirror 113, 114, 115, 116 are provided. Red light and blue light reflected by the dichroic mirror 104 enter the dichroic mirror 111. The red light is transmitted through the dichroic mirror 111, and the blue light is reflected by the dichroic mirror 111 and enters the blue image display element 4b. The red light transmitted through the dichroic mirror 111 is reflected by the total reflection mirrors 113 and 114 and enters the red video display element 3b.

  On the other hand, the green light transmitted through the dichroic mirror 104 enters the mirror 112. Part of the green light is reflected by the mirror 112 and is incident on the second green image display element 2 b, and the rest is transmitted through the mirror 112. Further, the green light transmitted through the mirror 112 is reflected by the total reflection mirrors 115 and 116, and enters the first green image display element 1b. Light incident from the back of each video display element passes through each video display element and is output as video readout light. The method of synthesizing the respective video readout lights and projecting them by the projection lens 12 is the same as in the ninth embodiment, and thus the description thereof is omitted.

  According to the present embodiment, similarly to the ninth embodiment, it is possible to synthesize and project the image readout light from the four image display elements, and the distance from the four image display elements to the projection lens 12. Can be made short and uniform. In addition, high-definition video display by pixel shift can be realized with a compact configuration using a single light source 101. Similarly to the ninth embodiment, since the first green image display element 1a and the second green image display element 2a are arranged facing the same PBS 8, high accuracy with less change with time is obtained. High-definition video display by shifting pixels can be realized.

(Eleventh embodiment)
Next, an eleventh embodiment of the present invention will be described. FIG. 12 shows the configuration of the video projection apparatus according to the present embodiment. Below, it demonstrates centering on the difference with 9th Embodiment (FIG. 10). In the present embodiment, a reflective video display element (first green video display element 1a, second green video display element 2a, red video display element 3a, blue video display element 4a) is used.

  In FIG. 12, a light source 121 that outputs light in the red and blue wavelength bands and a light source 122 that outputs light in the green wavelength band are provided. The light output from the light source 121 is collimated and uniformed, passes through the polarization conversion element 123, and after the polarization direction is aligned in a certain direction, only the light in the red wavelength band is converted by 90 degrees. The light passes through the phase conversion filter 124 and enters the PBS 5 as red light (S-polarized light) and blue light (P-polarized light) having polarization directions different from each other by 90 degrees.

  On the other hand, the light output from the light source 122 is collimated and uniformed, passes through the polarization conversion element 125, and after the polarization direction is aligned in a certain direction, the polarization direction is about half that of the light in the green wavelength band. Is transmitted through the phase conversion filter 126 that converts 90 degrees of the light, and enters the PBS 8 as two types of green light of S-polarized light and P-polarized light having polarization directions different from each other by 90 degrees. If the output light of the light source has no polarization characteristic bias, the polarization converter 125 and the phase conversion filter 126 are unnecessary. The method of causing the light incident on the PBSs 5 and 8 to enter each image display element, outputting the image readout light, synthesizing each image readout light, and projecting by the projection lens 12 is the same as in the ninth embodiment. Is omitted.

  According to the present embodiment, similarly to the ninth embodiment, it is possible to synthesize and project the image readout light from the four image display elements, and the distance from the four image display elements to the projection lens 12. Can be made short and uniform. Further, by using an LED light source as the light sources 121 and 122, the light source can be reduced in size. Similarly to the ninth embodiment, since the first green image display element 1a and the second green image display element 2a are arranged facing the same PBS 8, high accuracy with less change with time is obtained. High-definition video display by shifting pixels can be realized.

(Twelfth embodiment)
Next, a twelfth embodiment of the present invention will be described. FIG. 13 shows the configuration of the video projection apparatus according to the present embodiment. Below, it demonstrates centering on the difference with 10th Embodiment (FIG. 11). In the present embodiment, transmissive video display elements (first green video display element 1b, second green video display element 2b, red video display element 3b, blue video display element 4b) are used.

  In FIG. 13, a light source 131 that outputs red light, a light source 132 that outputs blue light, and light sources 133 and 134 that output green light are provided. In addition, polarization conversion elements 135, 136, 137, and 138 for aligning the polarization direction of the output light are provided.

  The light output from the light source 131 passes through the polarization conversion element 135 and is incident on the red image display element 3b after the polarization direction is aligned in a certain direction. The light output from the light source 132 passes through the polarization conversion element 136 and is incident on the blue image display element 4b after the polarization direction is aligned in a certain direction. The light output from the light source 133 is transmitted through the polarization conversion element 137 and is incident on the first green image display element 1b after the polarization direction is aligned in a certain direction. The light output from the light source 134 passes through the polarization conversion element 138 and is incident on the second green image display element 2b after the polarization direction is aligned in a certain direction.

  Light incident from the back of each video display element passes through each video display element and is output as video readout light. The method of synthesizing each video readout light and projecting it by the projection lens 12 is the same as that in the eleventh embodiment, so that the description is omitted.

  According to the present embodiment, similarly to the tenth embodiment, it is possible to synthesize and project the image readout light from the four image display elements, and the distance from the four image display elements to the projection lens 12. Can be made short and uniform. Further, by using an LED light source as the light sources 131, 132, 133, and 134, the light source can be reduced in size as in the tenth embodiment. Further, as in the tenth embodiment, the first green image display element 1a and the second green image display element 2a are disposed facing the same PBS 8, so that there is less change with time and high accuracy. High-definition video display by shifting pixels can be realized.

(13th Embodiment)
Next, a thirteenth embodiment of the present invention is described. In the present embodiment, the video projection apparatus according to each of the above embodiments is applied to a stereoscopic video projection system. FIG. 14 shows a schematic configuration of the stereoscopic video projection system according to the present embodiment.

  As shown in FIG. 14, the output light from the four-plate synthesis optical block 141 that synthesizes and outputs the image readout light from the four image display elements described in the above embodiments is configured by a projection lens or the like. Is projected by the projected shadow optical system 142 to form a projected image 143. This projected image 143 enters a lens array 144 in which a large number of microlenses are arranged. By observing an image output from the lens array 144, it is possible to observe a stereoscopic image based on a principle such as lenticular or integral photography. Here, regarding the projection image 143, the projection image 143 may be formed by projecting the synthesized light on the rear projection diffusion screen, or by directly projecting the synthesized light onto the microlens array 144. The projected image 143 may be formed.

  According to the present embodiment, a stereoscopic image based on a principle such as a lenticular or an integral method can be displayed by combining a lens array with a video projection device. The influence of the geometric distortion caused by the projection lens on the stereoscopic image is very large, and it is necessary to suppress the distortion rate to about 0.05% or less at the edge of the screen. In the video projection apparatus of the present invention, since there is one projection lens, the optical system is simple, and prism-shaped optical elements can be used, there are few factors that cause distortion. For this reason, a projection image in which absolute geometric distortion is suppressed can be obtained, and application to stereoscopic image display becomes possible.

  As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to the above-described embodiments, and includes design changes and the like without departing from the gist of the present invention. .

It is a block diagram which shows the structure of the video projection apparatus by the 1st Embodiment of this invention. It is a block diagram which shows the structure of the video projection apparatus by the 2nd Embodiment of this invention. It is a block diagram which shows the structure of the video projection apparatus by the 3rd Embodiment of this invention. It is a reference figure which shows the transmittance | permeability characteristic of the dichroic mirror 34 which the video projector by the 3rd Embodiment of this invention has. It is a block diagram which shows the structure of the video projection apparatus by the 4th Embodiment of this invention. It is a block diagram which shows the structure of the video projector by the 5th Embodiment of this invention. It is a block diagram which shows the structure of the video projector by the 6th Embodiment of this invention. It is a block diagram which shows the structure of the video projector by the 7th Embodiment of this invention. It is a block diagram which shows the structure of the video projection apparatus by the 8th Embodiment of this invention. It is a block diagram which shows the structure of the video projector by the 9th Embodiment of this invention. It is a block diagram which shows the structure of the video projector by the 10th Embodiment of this invention. It is a block diagram which shows the structure of the video projection apparatus by the 11th Embodiment of this invention. It is a block diagram which shows the structure of the video projector by the 12th Embodiment of this invention. It is a block diagram which shows schematic structure of the stereo image projection system by the 13th Embodiment of this invention. It is a reference diagram for explaining pixel shift used in the video projection device according to each embodiment of the present invention.

Explanation of symbols

  1a, 1b ... 1st green image display element, 2a, 2b ... 2nd green image display element, 3a, 3b ... red image display element, 4a, 4b ... blue image display element, 5, 8, 11 ... PBS, 6, 9 ... phase conversion filter, 7, 10 ... polarizer, 12 ... projection lens

Claims (9)

A first video display element that outputs video readout light of a first color;
A second video display element that outputs a second color video readout light;
A third video display element that outputs video readout light of a third color;
A fourth image display element for outputting a fourth color image readout light;
A first optical element that outputs the first color video readout light and the second color video readout light incident from different directions in the same direction;
A second optical element that outputs the third color video readout light and the fourth color video readout light incident in different directions in the same direction;
The first color image readout light and the second color image readout light from the first optical element, and the third color image from the second optical element, which are incident from different directions. A third optical element that outputs the readout light and the video readout light of the fourth color in the same direction;
The first color video readout light, the second color video readout light, the third color video readout light, and the fourth color video readout light output from the third optical element. A projection lens for combining and projecting;
A video projection apparatus comprising: The first video display element, the second video display element, the third video display element, and the fourth video display element are reflective video display elements,
The first optical element further separates the first color light and the second color light incident from the same direction, and causes the first color light to enter the first video display element. , Making the second color light incident on the second image display element,
The second optical element further separates the third color light and the fourth color light incident from the same direction and causes the third color light to enter the third video display element. The image projection apparatus according to claim 1, wherein the fourth color light is incident on the fourth image display element. A white light source,
Separating the light of the first color, the light of the second color, the light of the third color, and the light of the fourth color from the light from the white light source; A fourth optical element that causes the light and the second color light to enter the first optical element, and the third color light and the fourth color light to enter the second optical element. When,
The video projection device according to claim 2, further comprising: A first light source that outputs the first color light and the second color light incident on the first optical element;
A second light source that outputs the third color light and the fourth color light incident on the second optical element;
The video projection device according to claim 2, further comprising:   The first image display element, the second image display element, the third image display element, and the fourth image display element are transmissive image display elements. Video projection device. A white light source,
A fourth optical element that separates light of the first color, light of the second color, light of the third color, and light of the fourth color from the light from the white light source;
The first color light separated by the fourth optical element is incident on the first video display element, and the second color light separated by the fourth optical element is incident on the second optical element. A first optical element group to be incident on the image display element;
The third color light separated by the fourth optical element is made incident on the third image display element, and the fourth color light separated by the fourth optical element is made into the fourth color. A second optical element group to be incident on the video display element;
The video projection device according to claim 5, further comprising: A first light source for generating light of a first color incident on the first image display element;
A second light source for generating a second color light incident on the second image display element;
A third light source for generating light of a third color incident on the third image display element;
A fourth light source that generates light of a fourth color incident on the fourth image display element;
The video projection device according to claim 5, further comprising:   The first video display element and the second video display element, or the third video display element and the fourth video display element are green video display elements that output green video readout light, respectively. The video projection device according to claim 1, wherein the green video readout light from the green video display element is shifted by a half pixel on the projected video. The video projection device according to any one of claims 1 to 8,
A lens array composed of a plurality of microlenses into which image readout light projected by the image projection device is incident;
A stereoscopic video projection system characterized by comprising:

Images