Stereoscopic display device and stereoscopic display method

Abstract

To provide a stereoscopic display device and a stereoscopic display method that display multiple parallax images with suitable image quality and light efficiency. [Solution] The stereoscopic display device comprises a light source unit with multiple light sources, an illumination optical system, an image display unit, a projection optical system, and a directional screen. The image display unit displays multiple parallax images in a time-division manner using illumination light from the light sources via the illumination optical system. The projection optical system comprises a first projection lens, multiple second projection lenses, and multiple third projection lenses. The number of multiple second projection lenses and the number of multiple third projection lenses are equal to the number of multiple parallax images. Each of the multiple second projection lenses has an entrance pupil at each position of the multiple light source images and images each of the multiple parallax images from each of the multiple light source images formed on the first projection lens. Each of the multiple third projection lenses projects each of the multiple parallax images imaged by each of the multiple second projection lenses onto the directional screen.

Description

Technical Field

[0001] The present invention relates to a stereoscopic display device and a stereoscopic display method.

Background Art

[0002] Stereoscopic display is achieved by presenting different images reflecting parallax to each of the observer's two eyes. Among stereoscopic display methods, there is a method of presenting different parallax images depending on the projection angle by giving directivity to each parallax image for display. According to this, an observer can visually recognize stereoscopic display without using a special device. Patent Document 1 describes a stereoscopic image display device in which a plurality of multi-viewpoint images displayed by a display device are projected so as to overlap in a second imaging unit, and an optical direction control optical system controls the direction of light that has passed through the second imaging unit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The stereoscopic image display device described in Patent Document 1 can simultaneously project a plurality of multi-viewpoint images and reproduce a stereoscopic image having parallax in all directions by controlling the direction of light that has passed through the second imaging unit by the optical direction control optical system. However, in the stereoscopic image display device described in Patent Document 1, the plurality of multi-viewpoint images projected by the plurality of display devices can display only the video in the direction of the simultaneously projected viewpoints, resulting in a decrease in image quality.

[0005] In view of the above problems, the present disclosure provides a stereoscopic display device and a stereoscopic display method that are suitable in image quality and have good light efficiency because the number of parallaxes of multi-viewpoint images by a display device can be increased by time division.

Means for Solving the Problems

[0006] A stereoscopic display device according to one aspect of this disclosure comprises a light source unit, an illumination optical system, an image display unit, a projection optical system, and a directional screen. The light source unit comprises a plurality of light sources and a light source control unit and illuminates the image display unit. The illumination optical system illuminates the image display unit with illumination light from the light source unit. The image display unit comprises an image display element and an image control unit and displays a plurality of corresponding parallax images in a time-division multiplexing manner using the plurality of illumination lights. The image control unit is connected to the light source control unit and outputs synchronization information to the light source control unit based on a control signal to the image display element. The light source control unit controls each of the plurality of light sources based on the synchronization information obtained from the image control unit. The projection optical system comprises a first projection lens, a plurality of second projection lenses, and a plurality of third projection lenses. The number of the plurality of second projection lenses and the number of the plurality of third projection lenses are equal to the number of parallax images. The first projection lens forms a plurality of light source images corresponding to the plurality of illumination lights and converts them into parallel light. Each of the multiple second projection lenses has an entrance pupil at the position of each of the multiple light source images corresponding to the multiple parallax images, and images each of the multiple parallax images from each of the multiple light source images formed on the first projection lens. Each of the multiple third projection lenses projects each of the multiple parallax images imaged by each of the multiple second projection lenses onto a directional screen. The directional screen displays the projected multiple parallax images with directionality.

[0007] A stereoscopic display method according to one aspect of this disclosure uses a light source unit comprising a plurality of light sources and a light source control unit, an illumination optical system, an image display unit, a projection optical system, and a directional screen. The stereoscopic display method includes an illumination step, a projection step, and a display step. In the illumination step, the light source control unit acquires parallax identification information that identifies the position of the parallax image to be displayed, a light source at a position corresponding to the parallax identification information projects illumination light onto the image display unit via the illumination optical system, and the image display unit displays the parallax image corresponding to the parallax identification information using the illumination light. In the projection step, the projection optical system converts the light source image corresponding to the illumination light into parallel light, forms an image of the parallax image corresponding to the parallax identification information from the light source image, and projects the formed parallax image corresponding to the parallax identification information onto the directional screen. In the display step, the directional screen displays the projected parallax image corresponding to the parallax identification information with directionality. The stereoscopic display method repeats the display of a predetermined number of parallax images up to the number of frames of the display video. [Effects of the Invention]

[0008] According to this disclosure, the number of parallaxes of multi-view images displayed by the display device can be increased by time division, thereby providing a stereoscopic display device and a stereoscopic display method that offer suitable image quality and good optical efficiency. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram of a stereoscopic display device according to Embodiment 1. [Figure 2] This is a flowchart of the 3D display method according to Embodiment 1. [Figure 3] This is a schematic diagram of a stereoscopic display device according to Embodiment 2. [Figure 4] This is a control signal for the light source control unit according to Embodiment 2. [Figure 5] This is a schematic diagram of a stereoscopic display device according to Embodiment 3. [Figure 6] This is a projection diagram of the light source image onto the first projection lens of the projection optical system according to Embodiment 4. [Figure 7] This is a schematic diagram of the stereoscopic display device 5 according to Embodiment 5. [Figure 8]This is a schematic diagram of an illumination optical system according to Embodiment 5, which includes a fly-eye lens and a condenser lens. [Figure 9] This is a schematic diagram of the illumination optical system according to Embodiment 5, which is equipped with a fly-eye lens. [Figure 10] This is a schematic diagram of the illumination optical system according to Embodiment 5, which includes a light tunnel. [Modes for carrying out the invention]

[0010] The present invention will be described below through embodiments of the invention, but the invention claimed is not limited to the following embodiments. Furthermore, not all of the configurations described in the embodiments are necessarily essential as means of solving the problem. For clarity of explanation, the following descriptions and drawings have been omitted and simplified as appropriate. In each drawing, the same elements are denoted by the same reference numerals, and redundant explanations have been omitted where necessary.

[0011] <Embodiment 1> A stereoscopic display device according to Embodiment 1 will be described with reference to Figure 1. Figure 1 is a schematic diagram of the stereoscopic display device 1 according to Embodiment 1. The stereoscopic display device 1 comprises a light source unit 10, an illumination optical system 20, an image display unit 30, a projection optical system 40, and a directional screen 50. In Figure 1, the dashed lines indicate the centerlines of the illumination optical system 20, the image display unit 30, and the projection optical system 40. Note that in Figure 1, only representative arrangements of the projection optical system 40 are shown for those where the same configuration is arranged consecutively.

[0012] The light source unit 10 has a light source that generates illumination light. The light source unit 10 illuminates the image display unit 30 via the illumination optical system 20. The illumination light emitted from the light source unit 10 passes through the illumination optical system 20 and is projected onto the image display unit 30. The light source unit 10 includes a plurality of light sources 101 and a light source control unit 102. The plurality of light sources 101 illuminate the image display unit 30 in a time-division manner via the illumination optical system 20. The light source 101 is, for example, an LED (light-emitting diode). The light source control unit 102 controls the plurality of light sources 101 of the light source unit 10. The light source control unit 102 is connected to the image display unit 30.

[0013] The illumination optical system 20 projects the illumination light projected from the light source unit 10 onto the corresponding image display unit 30. The illumination optical system 20 is, for example, a biconvex lens used as an illumination lens.

[0014] The image display unit 30 displays a plurality of parallax images using the illumination light projected through the illumination optical system 20. The light constituting the image displayed on the image display unit 30 is projected onto the projection optical system 40. The image display unit 30 includes an image display element 301 and an image control unit 302.

[0015] The image display element 301 displays a parallax image. The image display element 301 is, for example, a DMD (Digital Micromirror Device) and displays an image by controlling the reflection direction of the illumination light. (Although the DMD is controlled by reflected light, it is illustrated as being controlled by transmission for simplicity. In reality, the illumination light is controlled by reflection via a prism or the like to display an image.) Alternatively, the image display element 301 is, for example, a color filter and a liquid crystal panel used in an LCD (Liquid Crystal Device), and displays an image by transmitting the illumination light restricted by the liquid crystal panel through the color filter. The image control unit 302 outputs a control signal to the image display element 301. The image control unit 302 outputs synchronization information based on the control signal to the image display element 301.

[0016] The projection optical system 40 projects each of the plurality of parallax images displayed on the image display unit 30 to a corresponding position on the directional screen 50. The projection optical system 40 includes a first projection lens 401, a plurality of second projection lenses 402, and a plurality of third projection lenses 403. Here, the number of the second projection lenses 402 is the same as the number of the parallax images to be projected. Similarly, the number of the third projection lenses 403 is equal to the number of the parallax images to be projected.

[0017] The first projection lens 401 forms a plurality of light source images that are illuminated and formed on the image display unit 30 by the illumination optical system 20 and the plurality of light sources 101 of the light source unit 10. The first projection lens 401 functions as a collimating lens, projects each of the plurality of light source images as parallel light to the second projection lens 402, and forms the plurality of light source images at different positions in a plane orthogonal to the optical axis. Here, the light source image is an image of the light source viewed from the projection side.

[0018] Each of the second projection lenses 402 has an entrance pupil at the position of each light source image corresponding to the parallax image formed by the first projection lens 401. The entrance pupil is an image of the aperture of the optical system viewed from the incident side. Each of the second projection lenses 402 forms an image of each parallax image by the illumination light from each of the light source images formed by the first projection lens 401. The third projection lens 403 projects the parallax images formed by each of the second projection lenses 402 onto the directional screen 50.

[0019] The directional screen 50 displays the plurality of parallax images projected by the third projection lens 403 with directivity. The directional screen 50 has directivity and displays each parallax image in the direction projected by the third projection lens 403.

[0020] Figure 2 is a flowchart of the stereoscopic display method according to Embodiment 1. Here, the stereoscopic display method performs stereoscopic display where the number of parallax is n and the number of video frames of the displayed image is m. n and m are arbitrary natural numbers. The stereoscopic display method according to Embodiment 1 includes steps S11 to S14. In Figure 2, the determination of the process is explained using a count-up for simplicity, but it is not limited to this, and methods such as a count-down may also be used.

[0021] In step S11, the i-th light source 101 of the light source unit 10 illuminates the image display unit 30 via the illumination optical system 20. Here, i is parallax identification information that identifies the position of the parallax image to be displayed. Next, in step S12, the image display unit 30 displays the j-th video frame of the i-th parallax image. Here, j is frame identification information that identifies the video frame to be displayed. Steps S11 and S12 together are also called the illumination process. In step S13, the first projection lens 401 projects onto the i-th second projection lens 402, which corresponds to the i-th light source 101 of the light source unit 10.

[0022] In step S14, the i-th second projection lens 402 projects onto the directional screen 50 via the i-th third projection lens 403. Steps S13 and S14 together are also called the projection process. The directional screen 50 displays with directionality as part of the display process. The stereoscopic display device 1 repeats steps S11 to S14 n times, and this repetition loops up to the mth frame for each frame number, displaying all the parallax images of each video frame. Parallax identification information and frame identification information are acquired and controlled by the light source control unit.

[0023] As described above, the stereoscopic display device 1 according to this embodiment projects the light source image formed on the first projection lens 401 onto the directional screen 50 in a time-division manner using the second projection lens 402 and the third projection lens 403. This allows the second projection lens 402 and the third projection lens 403 to project an increased number of parallax images in a time-division manner, thus enabling the projection of the increased parallax images onto the directional screen 50 in a time-division manner. Therefore, the stereoscopic display device 1 according to this embodiment displays stereoscopic images with suitable image quality and optical efficiency.

[0024] <Embodiment 2> Figure 3 is a schematic diagram of a stereoscopic display device 2 according to Embodiment 2. The stereoscopic display device 2 displays multiple parallax images in a time-division manner. The stereoscopic display device 2 shown in Figure 3 comprises a light source unit 11, an illumination optical system 21, an image display unit 31, a projection optical system 41, and a directional screen 51. The stereoscopic display device 2 has some of the same configuration as the stereoscopic display device 1 described with reference to Figure 1. Therefore, redundant explanations of the configuration of the stereoscopic display device 2 are omitted. In Figure 3, dotted lines indicate the illumination range of the illumination light, and dashed lines show examples of optical paths. The dashed lines indicate the centerlines of the illumination optical system 21, the image display unit 31, and the projection optical system 41. In Figure 3, only representative arrangements are shown for the light source unit 11 and the projection optical system 41 where the same configuration is arranged consecutively.

[0025] In the stereoscopic display device 2, the light source unit 11 comprises a plurality of light sources 111 and a light source control unit 112. The plurality of light sources 111 illuminate the image display unit 31 in a time-division manner via the illumination optical system 21. Each of the plurality of light sources 111 corresponds to a parallax image and is a light-emitting element of the corresponding color. The plurality of light sources 111 have, for example, light sources of the corresponding colors in the three primary colors of light. Specifically, the plurality of light sources 111 are red, green, and blue LEDs, etc. The plurality of light sources 111 may also include a white light source. The number of light sources of each color may differ depending on the image to be displayed. The plurality of light sources 111 do not have to include any of the red, green, and blue light sources. Alternatively, the plurality of light sources 111 may consist only of white light sources, and the light may pass through filters of each color in the image display unit 31. The plurality of light sources 111 are controlled by the light source control unit 112.

[0026] The light source control unit 112 controls the multiple light sources 111 of the light source unit 11. The light source control unit 112 is connected to the image display unit 31. The light source control unit 112 acquires a vertical synchronization signal as synchronization information from the image display unit 31 and controls each of the multiple light sources 111 based on the vertical synchronization signal. The light source control unit 112 may be implemented with dedicated hardware. Alternatively, part or all of the light source control unit 112 may be implemented by general-purpose or dedicated circuits, processors, etc., or a combination thereof. These may be configured by a single chip or by multiple chips connected via a bus. Part or all of the light source control unit 112 may be implemented by a combination of the above-mentioned circuits, etc., and a program. The processor is a CPU (Central Processing Unit), FPGA (Field-Programmable Gate Array), etc.

[0027] Figure 4 shows the control signal of the light source control unit 112 according to Embodiment 2. In Figure 4, the horizontal axis represents time t, and the vertical axis represents the on / off state of the signal. In Figure 4, the light source control unit 112 outputs control signals based on the vertical synchronization signal to 12 light sources 111 corresponding to the three colors red, blue, and green for the four disparity images. In Figure 4, the light source control unit 112 controls the 12 light sources 111. Here, R N This is the control signal to the red light source corresponding to the Nth disparity image (where N is an integer between 1 and 4). N This is a control signal to the green light source corresponding to the Nth disparity image. N This is a control signal to the blue light source corresponding to the Nth disparity image.

[0028] Upon receiving the vertical synchronization signal, the light source control unit 112 outputs control signals to the light sources 111 in the order of red, green, and blue for each parallax image. Here, the control signals operate each color light source 111 sequentially for a predetermined time without temporal overlap. When the light source control unit 112 receives the next vertical synchronization signal, it outputs operation signals to the color light sources 111 corresponding to the next parallax image.

[0029] Here, the vertical synchronization signal may include identification information to identify the disparity image. This allows the light source control unit 112 to illuminate the light source 111 corresponding to the disparity image even after the synchronization state with the image display unit 31 has shifted. Therefore, the stereoscopic display device 2 can display images in 3D without causing synchronization errors.

[0030] The illumination optical system 21 illuminates the image display unit 31 with illumination light from multiple light sources 111 of the light source unit 11. The illumination optical system 21 consists of an illumination collimator lens 211 and an illumination field lens 212. The illumination collimator lens 211 is positioned behind the light source unit 11. The illumination collimator lens 211 makes the illumination light from the multiple light sources 111 into parallel light. Here, the light sources 111 and the illumination collimator lens 211 are positioned close together, and the range of illumination light shown by the dotted line in Figure 3 extends from the illumination collimator lens 211 to the illumination field lens 212. The illumination field lens 212 refracts the illumination light from the light sources 111, which has been made into parallel light by the illumination collimator lens, toward the image display unit 31. As a result, the illumination optical system 21 projects the illumination light from the light source unit 11 to the image display unit 31 in a suitable manner.

[0031] Here, the illumination optical system 21 telecentrically projects illumination light from multiple light sources 111 between the illumination collimator lens 211 and the illumination field lens 212. Telecentric refers to a state in which the optical axis of the illumination optical system 21 and the principal rays of illumination light from each light source 111 can be considered parallel. In other words, between the illumination collimator lens 211 and the illumination field lens 212, the principal rays of illumination light from the multiple light sources 111 may be offset by, for example, ±5 degrees from the optical axis of the illumination optical system 21. With this configuration, the illumination optical system 21 can uniformly project illumination light from the light source unit 11 onto the image display unit 31. Furthermore, the illumination optical system 21 can efficiently transmit illumination light from the light source unit 11 to the image display unit 31 without causing distortion aberration.

[0032] The image display unit 31 comprises a DMD 311 and a DMD control unit 312. The DMD 311 reflects light sources of each color in a time-division manner for each parallax image and displays each parallax image. This allows one DMD to display multiple parallax images. Furthermore, the image display unit 31 can display multiple parallax images with suitable image quality and light efficiency by efficiently utilizing the illumination light from each light source without occluding it. The DMD 311 may be an image display element other than a DMD. The DMD control unit 312 outputs control signals to the DMD 311. The DMD control unit 312 is also connected to the light source control unit 112 and outputs a vertical synchronization signal based on the control signals as synchronization information. The DMD control unit 312 is also called the image control unit.

[0033] Here, the DMD control unit 312 may be implemented with dedicated hardware. Alternatively, part or all of the DMD control unit 312 may be implemented by general-purpose or dedicated circuitry, a processor, etc., or a combination thereof. These may be configured on a single chip or on multiple chips connected via a bus. Part or all of the DMD control unit 312 may be implemented by a combination of the above-mentioned circuitry etc. and a program. The processor is a CPU, FPGA, etc. Note that the DMD control unit 312 may be configured integrally with the light source control unit 112.

[0034] The projection optical system 41 includes an imaging field lens 414 and a projection field lens 415. The imaging field lens 414 is positioned between the image display unit 31 and the first projection lens 401. The imaging field lens projects the illumination light of each parallax image displayed by the DMD 311 to the corresponding position on the first projection lens 401. In this way, the imaging field lens 414 prevents the illumination light of different parallax images from overlapping on the first projection lens 401.

[0035] The projection field lens 415 is positioned between the second projection lens 402 and the third projection lens 403. The projection field lens 415 is positioned where the second projection lens 402 forms an image of each of the parallax images. The projection field lens 415 projects illumination light that is projected from the second projection lens 402 and is outside the entrance pupil of the third projection lens 403 onto the third projection lens 403. Thus, the projection optical system 41 can suitably project the parallax image onto the directional screen 51. The number of projection field lenses 415 may be equal to the number of second projection lenses.

[0036] Here, the second projection lens may be set so that the light beam does not spread. Therefore, the diameter of the exit pupil of the second projection lens 402 and the diameters of the respective primary images of the parallax image formed by the second projection lens 402 are approximately equal. Here, "approximately equal" means a state in which the diameter of the exit pupil of the second projection lens 402 and the diameters of the respective primary images of the parallax image formed by the second projection lens 402 can be considered to be equal. In other words, there may be a 5% difference between the diameter of the exit pupil of the second projection lens 402 and the diameters of the respective primary images of the parallax image formed by the second projection lens 402. According to this, the illumination optical system 21 can be easily handled with mirrors, etc., because the length of the optical path can be secured and the light beam does not spread.

[0037] The directional screen 51 is a vertically diffuse retroreflective screen. A vertically diffuse retroreflective screen is a screen that strongly diffuses light from the light source 11 side in the vertical direction and weakly in the horizontal direction, and retroreflectives light from the observer side. According to this, based on the directional properties of the parallax images projected by the third projection lens 403, the stereoscopic display device 2 can display each parallax image only in its corresponding direction in the horizontal direction, and diffuse the parallax image in the vertical direction. Therefore, the stereoscopic display device 2 can display each parallax image continuously and densely in the horizontal direction, and can display an image that is not affected by the vertical movement of the observer. In other words, the stereoscopic display device 2 can perform horizontal parallax display type stereoscopic display.

[0038] As described above, the stereoscopic display device 2 according to this embodiment can display stereoscopic images with more favorable image quality and light efficiency by illuminating the image display unit 31 with illumination light from the light source unit 11 in a time-division manner.

[0039] Furthermore, the DMD control unit 312 of the image display unit 31 may adjust the control amount of the DMD 311 for each color light source related to each parallax image based on the image misalignment information. The image misalignment information includes at least one of the positional misalignment and rotational misalignment of each color related to each parallax image projected onto the third projection lens 403. In addition, the light source control unit 112 may adjust the position of the corresponding light source 111 based on the image misalignment information. Here, the image misalignment information is acquired from a sensor, for example, by providing a sensor near the third projection lens 403. Alternatively, the image misalignment information may be input by the user of the stereoscopic display device 2 via an interface (not shown).

[0040] Image misalignment information may be set in advance. Image misalignment information may be acquired when the stereoscopic display device 2 is started up. Image misalignment information may be acquired when the stereoscopic display device 2 is instructed to correct the image position from an interface such as a button (not shown). Furthermore, image misalignment information may be acquired at predetermined time intervals.

[0041] According to this, the stereoscopic display device 2 can correct image misalignment caused by differences in the positions of the multiple light sources 111 of the light source unit 11. Furthermore, the stereoscopic display device 2 can correct image misalignment caused by tilt of the installation position or changes in the position of the internal components.

[0042] <Embodiment 3> Figure 5 is a schematic diagram of a stereoscopic display device 3 according to Embodiment 3. The stereoscopic display device 3 magnifies parallax. The stereoscopic display device 3 comprises a light source unit 11, an illumination optical system 21, an image display unit 31, a projection optical system 42, and a directional screen 51. In Figure 5, for simplicity, some components of the light source unit 11, the image display unit 31, and the directional screen 51 are omitted and not shown. The stereoscopic display device 3 has some of the same configuration as the stereoscopic display device 2 described with reference to Figure 3. Therefore, redundant explanations of the configuration of the stereoscopic display device 3 are omitted. In Figure 5, the dashed lines show typical light ray paths.

[0043] In Figure 5, the light illuminated by the light source 11 is shown as passing through the image display element of the image display unit 31, but it can also be used as a reflector (DMD, etc.). The rectangular area on the right, shown as the illumination field lens 212, represents a prism, and the rectangular area on the left, shown as the imaging field lens 414, represents a prism identical to that of the illumination prism. Light incident on the prism is refracted on the incident side, totally internally reflected at the prism interface, incident on the display element, and the light reflected by the image display element passes through the prism and exits. This structure is called a TIR (Total Internal Reflection) prism. Similarly, a structure in which incident light is refracted and transmitted, and totally internally reflected at the prism interface on the exit side, is called an R-TIR (Reverse-Total Internal Reflection) prism. Structures using TIR prisms or R-TIR prisms can also be used in this way.

[0044] The projection optical system 42 includes at least one parallax magnifying element 426 behind the second projection lens 402. The parallax magnifying element 426 is an optical element. The parallax magnifying element 426 is, for example, a mirror or a prism. The parallax magnifying element 426 is positioned between the second projection lens and the third projection lens. The parallax magnifying element 426 bends at least one path of illumination light that passes over multiple parallax images separated by the second projection lens 402, thereby widening the spacing between the parallax images. As a result, the stereoscopic display device 3 can achieve a large parallax relative to the size of the illumination optical system 21 and the projection optical system 42.

[0045] In Figure 5, the multiple parallax magnifying elements 426 magnify the parallax between the two parallax images. Each of the parallax-magnified parallax images is projected onto the directional screen 51 after being magnified by the parallax magnifying elements 426.

[0046] Furthermore, the projection optical system 42 may reroute the optical path for each parallax image using mirrors or the like. This allows the projection optical system 42 to adjust the projection distance to the directional screen for each parallax image. In this case, since the directional screen 51 has vertical diffusion properties, the exit pupil of the third projection lens 403 may be shifted vertically if the horizontal parallax is equidistant. Here, the exit pupil is the light source image created by the optical system as seen from the projection side. Also, by adjusting the image magnification of the projection field lens, the position of the exit pupil of the third projection lens 403 as seen from the directional screen may be shifted forward or backward, as long as the projected light is not obstructed.

[0047] As described above, the stereoscopic display device 3 according to this embodiment includes at least one parallax-enhancing element behind the second projection lens, and by enlarging the spacing for at least one parallax image, it is possible to display a stereoscopic image with a large parallax relative to the size of the optical system.

[0048] <Embodiment 4> The stereoscopic display device according to Embodiment 4 efficiently utilizes the first projection lens 401 to achieve suitable image quality and light efficiency of the projected parallax image. The stereoscopic display device comprises a light source unit 11, an illumination optical system 21, an image display unit 31, a projection optical system 43, and a directional screen 51. The stereoscopic display device has a partially the same configuration as the stereoscopic display device 3 described with reference to Figure 5. Therefore, redundant explanations of the configuration of the stereoscopic display device are omitted. Furthermore, the overall configuration of the stereoscopic display device is the same as that of the stereoscopic display device 3 described with reference to Figure 5, except that the projection optical system 42 is replaced by the projection optical system 43, so it is omitted from the illustration.

[0049] The projection optical system 43 according to Embodiment 4 includes a first correction element 437 and a second correction element 438 instead of the parallax magnifying element 426. The projection optical system 43 corrects the position of the light source image 4011 on the first projection lens from a planar shape to a horizontal linear shape. The transition of the projection position of the light source image 4011 of the projection optical system 43 according to Embodiment 4 will be explained with reference to Figure 6. Figure 6 is a projection diagram of the light source image onto the first projection lens 401 of the projection optical system 43 according to Embodiment 4. Note that Figure 6 is a view of the first projection lens 401 from the side of the second projection lens 402.

[0050] As shown in Figure 6(A), the first projection lens 401 of the projection optical system 43 has light source images 4011 that overlap multiple parallax images, arranged approximately point-symmetrically with respect to the center of the first projection lens 401. Figure 6(A) is a diagram showing the arrangement of light source images 4011 on the first projection lens 401 according to Embodiment 4. Here, approximately point-symmetric means a state in which the light source images 4011 can be considered to be arranged point-symmetrically with respect to the center of the first projection lens 401. The light source images 4011 may be shifted, for example, by 5% of the size of the light source image 4011 with respect to the point-symmetric position.

[0051] According to this, the stereoscopic display device can arrange each of the light source images 4011 to be larger without overlap than by arranging multiple light source images 4011 linearly on the first projection lens 401. Therefore, the projection optical system 43 can efficiently utilize the entire first projection lens 401, and can realize a parallax image with suitable image quality and light efficiency.

[0052] Furthermore, the light source unit 11 may be configured such that the light source images 4011 on the first projection lens 401, which are superimposed on multiple parallax images, are arranged approximately point-symmetrically with respect to the center of the first projection lens 401. The illumination optical system 21 may also be designed such that the light source images 4011 on the first projection lens 401, which are superimposed on multiple parallax images, are arranged approximately point-symmetrically with respect to the center of the first projection lens 401.

[0053] The first correction element 437 and the second correction element 438 are positioned between the second projection lens 402 and the third projection lens 403. The first correction element 437 and the second correction element 438 project light from the light source image 4011 formed on the first projection lens 401 onto the third projection lenses 403, which are arranged at approximately equal intervals in a horizontal straight line. Here, the horizontal direction is the direction in which the diffusion of transmitted light is weak in the directional screen 51. Furthermore, approximately equal intervals refer to a state in which the intervals between the third projection lenses 403 corresponding to adjacent parallax images in the projection optical system 43 as seen from the directional screen 51 can be considered equal. The intervals between the third projection lenses 403 corresponding to adjacent parallax images may be shifted by, for example, 5% depending on the combination of adjacent third projection lenses 403.

[0054] The first corrector element 437 and the second corrector element 438 are optical elements. The first corrector element and the second corrector element are, for example, mirrors or prisms. The first corrector element 437 and the second corrector element 438 may also function as parallax magnifying elements 426.

[0055] Figure 6(B) shows the projection position of the light source image 4012 corrected by the first correction element 437. The first correction element 437 projects the light source image 4012, shown by the dashed line, by widening the distance in the radial direction of the first projection lens 401, as indicated by the arrow, from the light source image 4011, which is placed on the first projection lens 401, shown by the dotted line. Alternatively, the first correction element 437 may direct some of the illumination light that falls on the light source image 4011 in a straight line and project the position of the light source image 4012 relative to the first projection lens 401 onto the figure.

[0056] Figure 6(C) shows the projection position of the light source image 4013 corrected by the second correction element 438. The second correction element 438 corrects the position of the light source image 4012 projected at the position indicated by the dotted line, as shown by the arrows, and projects each of the light source images 4013 at approximately equal intervals in a horizontal straight line as shown by the dashed line. Note that the first correction element 437 and the second correction element 438 may be realized by a single optical element.

[0057] According to this, the stereoscopic display device can project each of the light source images 4011, which are distributed planarly across the entire first projection lens 401, onto the third projection lenses 403, which are arranged in a straight line in the horizontal direction. Therefore, the stereoscopic display device can project a series of parallax images in a straight line in the horizontal direction at approximately equal intervals, and can realize a series of parallax images arranged continuously in the horizontal direction with suitable image quality and optical efficiency.

[0058] The projection optical system 43 may also include a third correcting element (not shown) between the second correcting element 438 and the third projection lens 403. The third correcting element is an optical element that refracts the optical axes of multiple light source images 4013 in the same direction. The third correcting element is, for example, a mirror or a prism. The angle at which the third correcting element refracts the optical axis is preferably 90 degrees, but is not particularly limited. The third correcting element may be placed for each light source image 4013, or it may be arranged to refract the optical axes of multiple light source images 4013. This improves the flexibility of configuration and arrangement of the stereoscopic display device, and allows for miniaturization.

[0059] As described above, the stereoscopic display device according to this embodiment efficiently utilizes the entire first projection lens 401 of the projection optical system 42, and can realize multiple parallax images arranged continuously in the horizontal direction with suitable image quality and optical efficiency.

[0060] <Embodiment 5> Figure 7 is a schematic diagram of the stereoscopic display device 5 according to Embodiment 5. The stereoscopic display device 5 according to Embodiment 5 displays images in 3D while avoiding crosstalk in the peripheral area of ​​the light source image. The stereoscopic display device 5 comprises a light source unit 11, an illumination optical system 24, an image display unit 31, a projection optical system 41, and a directional screen 51. The stereoscopic display device 5 has some of the same configuration as the stereoscopic display device 2 described with reference to Figure 3. Therefore, redundant explanations of the configuration of the stereoscopic display device 5 are omitted. In Figure 7, only representative arrangements are shown for the light source unit 11 and the projection optical system 41 where the same configuration is arranged consecutively.

[0061] The illumination optical system 24 includes a homogenizer 243. The homogenizer 243 homogenizes the illumination light. The homogenizer 243 is, for example, a pair of fly-eye lenses or a light tunnel. With this, the illumination optical system 24 can efficiently form a light source image. Therefore, the illumination optical system 24 can reduce crosstalk caused by the overlap of light source images in the projection optical system 41. As examples of the illumination optical system 24, an illumination optical system 25 equipped with a condenser lens and a fly-eye lens, an illumination optical system 26 equipped with a fly-eye lens, and an illumination optical system 27 equipped with a light tunnel will be described.

[0062] The illumination optical system 24 may further include a dichroic element (not shown). The dichroic element is a dichroic mirror or a dichroic prism. The dichroic element combines illumination light from each color light source to form composite light. This allows the illumination optical system 24 to efficiently share the optical system with each color light source, preventing color shifts due to differences in the position of the light sources.

[0063] Figure 8 is a schematic diagram of the illumination optical system 25 according to Embodiment 5, which includes a fly-eye lens and a condenser lens. The illumination optical system 25 is used in place of the illumination optical system 24 in Figure 7. The illumination optical system 25 includes a pair of fly-eye lenses 253 as a homogenizer. The illumination optical system 25 includes a cap lens 255, an illumination condenser lens 254, and an illumination collimator lens 211 to project parallel light onto the pair of fly-eye lenses 253. With this configuration, the illumination optical system 25 can focus the illumination light from the light source 11 and project it as parallel light onto the fly-eye lenses 253. In Figure 8, the dashed line indicates the center line of the illumination optical system 25.

[0064] Furthermore, the illumination optical system 25 includes a projection collimating lens 256 and an illumination field lens 212 behind a pair of fly-eye lenses 253. The projection collimating lens 256 and the illumination field lens 212 project homogenized illumination light onto the DMD 311.

[0065] As shown in Figure 8, the illumination optical system 25 is arranged in the following order from the light source unit 11 side: cap lens 255, illumination condenser lens 254, illumination collimator lens 211, a pair of fly-eye lenses 253, projection collimator lens 256, and illumination field lens 212.

[0066] Each light source 111 is provided with a cap lens 255. Illumination light from the light source 111 is diffused by the cap lens 255 and incident on the illumination condenser lens 254. The illumination condenser lens 254 projects an image of the light source onto the illumination collimator lens 211. The illumination collimator lens 211 makes the illumination light, which has formed the image of the light source, into parallel light. The parallel illumination light is projected onto a pair of fly-eye lenses 253 and homogenized. Subsequently, the illumination light projected from the fly-eye lenses 253 is focused by a projection collimator lens 256 and an illumination field lens 212 and projected onto the DMD 311. The illumination field lens 212 may be composed of an illumination lens group including a field lens. The illumination field lens 212 also functions as a relay lens. Here, the illumination condenser lens 254, illumination collimator lens 211, projection collimator lens 256, and illumination field lens 212 are shared by multiple light sources 111 of the light source unit 11.

[0067] The illumination optical system 25 can adjust the magnification of the exit pupil of the fly-eye lens 253 and the light source image on the image display unit 31 by the ratio of the focal length of the illumination field lens 212 to the focal length of the fly-eye lens 253. This allows the illumination optical system 25 to adjust the particle size of the light source image formed on each light source in the first projection lens 401 of the projection optical system 41, thereby preventing crosstalk between parallax images.

[0068] The illumination optical system 25 may also include a dichroic element (not shown) between the illumination condenser lens 254 and the illumination collimating lens 211. This allows the illumination light from each color light source 111 to be projected onto the fly-eye lens 253 as coaxial composite light. Therefore, the stereoscopic display device 5 equipped with the fly-eye lens 253 and the dichroic element can project a parallax image without the projection position of the illumination light changing for each color.

[0069] Figure 9 is a schematic diagram of the illumination optical system 26 according to Embodiment 5, which is equipped with a fly-eye lens. The illumination optical system 26 is used in place of the illumination optical system 24 in Figure 7. The illumination optical system 26 includes a pair of fly-eye lenses 263 as homogenizers. The illumination optical system 26 includes cap lenses 264 to project parallel light onto the fly-eye lenses 263. The cap lenses 264 are positioned so that the distance from each light source is equal to the focal length of the cap lenses 264. With this configuration, the illumination optical system 26 can disperse the illumination light from the light source 11 and project it onto the fly-eye lenses 263 as parallel light. In other words, the cap lenses 264 also function as illumination collimating lenses 211. In Figure 9, the dashed line indicates the center line of the illumination optical system 26.

[0070] Furthermore, the illumination optical system 26 includes a projection collimating lens 267 and an illumination field lens 212 behind a pair of fly-eye lenses 263. The projection collimating lens 267 and the illumination field lens 212 project homogenized illumination light onto the image display unit 31.

[0071] As shown in Figure 9, the illumination optical system 26 is arranged in the following order from the light source unit 11 side: cap lens 264, a pair of fly-eye lenses 263, projection collimating lens 267, and illumination field lens 212.

[0072] The cap lens 264 is, for example, a combination of a high refractive index lens 265 and an aspherical lens 266. The combination of the high refractive index lens 265 and the aspherical lens 266 allows for a higher numerical aperture and a shorter focal length. Therefore, the cap lens 264, which combines the high refractive index lens 265 and the aspherical lens 266, can be placed near the light source 11, allowing for a miniaturization of the illumination optical system 26.

[0073] Each light source 111 is provided with a cap lens 264. The illumination light from the light source 111 is diffused by the cap lens 264 to become parallel light. The parallel illumination light is projected onto a pair of fly-eye lenses 263 and homogenized. The illumination light projected from the fly-eye lenses 263 is then focused by a projection collimator lens 267 and an illumination field lens 212 and projected onto the DMD 311. The projection collimator lens 267 and the illumination field lens 212 may each be combination lenses. The illumination field lens 212 may also be composed of a lens group including a field lens. The illumination field lens 212 also functions as a relay lens. Here, the projection collimator lens 267 and the illumination field lens 212 are shared by the multiple light sources 111 of the light source unit 11.

[0074] The numerical aperture of the cap lens 264 may be lower than that of the fly-eye lens 263. This allows the illumination optical system 26 to suitably illuminate the image display unit 31 without emitting illumination light that is not used and is placed outside the image display unit 31.

[0075] The illumination optical system 26 may also include a dichroic element (not shown) between the cap lens 264 and the fly-eye lens 263. This allows the illumination light from each color light source 111 to be projected onto the fly-eye lens 263 as coaxial composite light. Therefore, the stereoscopic display device 5 equipped with the fly-eye lens 263 and the dichroic element can project a parallax image without the projection position of the illumination light changing for each color.

[0076] Furthermore, the illumination optical system 26 may include an illumination relay lens (not shown) between the dichroic elements or before the fly-eye lens 263. This allows the illumination optical system 26 to adjust the size of the light source image formed by the illumination light from the light source unit 11. In addition, the illumination optical system 26 can adjust the optical path for each light source.

[0077] Figure 10 is a schematic diagram of the illumination optical system 27 according to Embodiment 5, which includes a light tunnel. The illumination optical system 27 is used in place of the illumination optical system 24 in Figure 7. The illumination optical system 27 includes a light tunnel 273 as a homogenizer. The illumination optical system 27 includes a cap lens 274, an illumination collimator lens 211, and an illumination condenser lens 275 to project the light tunnel 273. With this configuration, the illumination optical system 27 can focus the illumination light from the light source 11 and project it onto the light tunnel 273. In Figure 10, the dashed line indicates the center line of the illumination optical system 27.

[0078] Furthermore, the illumination optical system 27 includes a projection condenser lens 276, a projection collimator lens 277, and an illumination field lens 212 behind the light tunnel 273. The projection condenser lens 276 and projection collimator lens 277 convert the homogenized illumination light into parallel light, and the illumination field lens 212 projects the homogenized illumination light, which has become parallel, onto the image display unit 31.

[0079] As shown in Figure 10, the illumination optical system 27 is arranged in the following order from the light source unit 11 side: cap lens 274, illumination collimator lens 211, illumination condenser lens 275, light tunnel 273, projection condenser lens 276, projection collimator lens 277, and illumination field lens 212.

[0080] Each light source 111 is provided with a cap lens 274. Illumination light from the light source 111 is diffused by the cap lens 274 and incident on the illumination collimator lens 211. The illumination collimator lens 211 makes the projected illumination light parallel. The parallel illumination light is focused by the illumination condenser lens 275 and projected onto the light tunnel 273. The light tunnel 273 homogenizes the projected illumination light. Illumination light incident on the light tunnel 273 propagates by repeatedly reflecting within the light tunnel 273. Subsequently, the illumination light projected from the light tunnel 273 becomes parallel light by a lens group consisting of a projection condenser lens 276, a projection collimator lens 277, and an illumination field lens 212, and is projected onto the DMD 311. Here, the projection collimator lens 277 and the illumination field lens 212 are shared by the multiple light sources 111 of the light source unit 11. Additionally, the illumination collimating lens 211 may be placed for each light source 111.

[0081] The illumination optical system 27 may also include a dichroic element (not shown) between the illumination collimating lens 211 and the illumination condenser lens 275. This allows the illumination light from each color light source 111 to be projected onto the light tunnel 273 as coaxial composite light. Therefore, the stereoscopic display device 5 equipped with the light tunnel 273 and the dichroic element can project a parallax image without the projection position of the illumination light changing for each color.

[0082] Furthermore, the illumination optical system 27 may include a relay lens (not shown) between the dichroic elements or before the light tunnel 273. This allows the illumination optical system 27 to adjust the size of the light source image formed by the illumination light from the light source unit 11. In addition, the illumination optical system 27 can adjust the optical path for each light source.

[0083] As described above, the stereoscopic display device 5 according to this embodiment is equipped with a homogenizer 243 in the illumination optical system 24 to form a homogenized light source image. Therefore, the stereoscopic display device 5 reduces crosstalk caused by overlapping light source images and can display images in stereoscopic form effectively.

[0084] The illumination optical system 24 may also include a three-dimensional arrangement of mirrors (not shown). This allows the stereoscopic display device 5 to be miniaturized by bending the optical path. To account for the positional shift of the light source image caused by reflection from the three-dimensional arrangement of mirrors, the light source unit 11 may be adjusted by rotating and asymmetrically arranging the light source. Furthermore, to account for chromatic aberration caused by reflection from the three-dimensional arrangement of mirrors, the light source unit 11 may adjust the position of the light source based on color. In addition, the illumination optical system 24 may use an internal total reflection prism and a prism corresponding to the inclination of the internal total reflection prism, in addition to the three-dimensional arrangement of mirrors, to avoid rotation of the light source image and fold back the optical path.

[0085] It should be noted that the present invention is not limited to the embodiments described above, and can be modified as appropriate without departing from the spirit of the invention. For example, each lens may be a lens group or a combination lens made up of multiple lenses. Furthermore, a combination of multiple lenses may be a single lens or a combination lens made up of multiple lenses. [Explanation of Symbols]

[0086] 1, 2, 3, 5 3D display device 10, 11 Light source section 20, 21, 24, 25, 26, 27 Illumination optical system 30, 31 Image display section 40, 41, 42, 43 Projection optical system 50, 51 Directional screens 101, 111 light source 102, 112 Light source control unit 211 Illumination Collimating Lens 212 Illumination Field Lens 243 Homogenizer 253 Fly-eye lenses 254 Illumination condenser lens 255 Cap Lens 256 Projection Collimating Lens 263 Fly-eye lens 264 Cap Lens 265 High refractive index lens 266 Aspherical Lenses 267 Projection Collimating Lens 273 Light Tunnel 274 Cap Lens 275 Illumination condenser lens 276 Projection Condenser Lens 277 Projection Collimating Lens 301 Image display element 302 Image Control Unit 311 DMD 312 DMD control section 401 First projection lens 402 Second projection lens 403 Third projection lens 414 Imaging Field Lens 415 Projection Field Lens 426 Parallax magnifying element 437 First Correction Element 438 Second Correction Element 4011, 4012, 4013 Light source image

Claims

1. A light source unit, an illumination optical system, an image display unit, a projection optical system, a directional screen, Equipped with, The light source unit comprises a plurality of light sources and a light source control unit, and illuminates the image display unit. The illumination optical system illuminates the image display unit with illumination light from the light source unit. The image display unit comprises an image display element and an image control unit, and uses a plurality of illumination lights to display a plurality of corresponding parallax images in a time-division manner. The image control unit is connected to the light source control unit and outputs synchronization information to the light source control unit based on the control signal to the image display element. The light source control unit controls each of the plurality of light sources based on the synchronization information obtained from the image control unit. The aforementioned projection optical system is A first projection lens that forms multiple light source images corresponding to each of the multiple illumination lights and converts them into parallel light, A plurality of second projection lenses, each having an entrance pupil at the position of each of the plurality of light source images corresponding to the plurality of parallax images, and forming an image of each of the plurality of parallax images from each of the plurality of light source images formed on the first projection lens, and Multiple third projection lenses project each of the multiple parallax images formed by each of the multiple second projection lenses onto the directional screen. Equipped with, The number of the plurality of second projection lenses and the plurality of third projection lenses is equal to the number of the plurality of disparity images. The directional screen displays the projected plurality of parallax images with directionality. 3D display device.

2. Each of the aforementioned plurality of light sources corresponds to each of the plurality of parallax images and is a light-emitting element of the corresponding color. The synchronization information includes identification information that identifies each of the multiple disparity images. The light source control unit controls each of the plurality of light sources corresponding to the identification information in a time-division manner for each color, based on the identification information. The stereoscopic display device according to claim 1.

3. Image displacement information is obtained, which includes at least one of the positional displacement and rotational displacement of the image projected by each of the plurality of third projection lenses. Based on the image shift information, the position of the plurality of light sources and at least one of the control amounts of the image display elements are adjusted. The stereoscopic display device according to claim 1.

4. The system further comprises at least one disparity widening element that widens the interval between at least one of the plurality of disparity images, The parallax magnifying element is positioned between each of the plurality of second projection lenses and each of the plurality of third projection lenses. A stereoscopic display device according to any one of claims 1 to 3.

5. The stereoscopic display device according to any one of claims 1 to 3, wherein the plurality of light source images on the first projection lens that are applied to the plurality of parallax images are arranged substantially point-symmetrically with respect to the center of the first projection lens.

6. A first correction element is positioned between the second projection lens and the third projection lens and projects the plurality of light source images with increased spacing in the radial direction from the first projection lens, A second correction element is positioned between the first correction element and the third projection lens, and projects the plurality of light source images in a horizontal linear direction at approximately equal intervals. A stereoscopic display device according to claim 5, comprising:

7. The stereoscopic display device according to claim 6, further comprising a third correcting element disposed between the second correcting element and the third projection lens, which refracts the optical axes of the plurality of light source images in the same direction.

8. The stereoscopic display device according to claim 1, wherein the illumination optical system further comprises a homogenizer for homogenizing the illumination light.

9. The illumination optical system further comprises a dichroic element between the light source and the homogenizer, The dichroic element makes the optical axes of at least two of the multiple light sources the same. The stereoscopic display device according to claim 8.

10. The illumination optical system further comprises an illumination condenser lens, an illumination collimating lens, a projection collimating lens, and an illumination field lens. The homogenizer is a pair of fly-eye lenses. The following components are arranged relative to the light source unit: the illumination condenser lens, the illumination collimating lens, the pair of fly-eye lenses, the projection collimating lens, and the illumination field lens, The stereoscopic display device according to claim 8 or 9.

11. The illumination optical system further comprises a cap lens, a projection collimating lens, and an illumination field lens. The homogenizer is a pair of fly-eye lenses. The cap lens converts the illumination light from the light source into parallel light. The light source unit is arranged in the following order: the cap lens, the pair of fly-eye lenses, the projection collimating lens, and the illumination field lens. The stereoscopic display device according to claim 8 or 9.

12. The illumination optical system further comprises an illumination collimating lens, an illumination condenser lens, a projection condenser lens, a projection collimating lens, and an illumination field lens. The homogenizer is a light tunnel, The following elements are arranged relative to the light source unit: the illumination collimating lens, the illumination condenser lens, the light tunnel, the projection condenser lens, the projection collimating lens, and the illumination field lens, The stereoscopic display device according to claim 8 or 9.

13. The aforementioned projection optical system comprises a plurality of projection field lenses, Each of the aforementioned plurality of projection field lenses is Between each of the plurality of second projection lenses and each of the plurality of third projection lenses, each of the plurality of second projection lenses is positioned to form an image of each of the plurality of parallax images. A stereoscopic display device according to any one of claims 1 to 3.

14. The directional screen is a vertically diffuse retroreflective screen, Each of the plurality of third projection lenses gives directionality to each of the plurality of parallax images and projects them onto the directional screen. A stereoscopic display device according to any one of claims 1 to 3.

15. The stereoscopic display device according to any one of claims 1 to 3, wherein the diameter of the exit pupil of the second projection lens and the diameter of each primary image of the plurality of parallax images formed by the second projection lens are approximately equal.

16. Using a light source unit equipped with multiple light sources and a light source control unit, an illumination optical system, an image display unit, a projection optical system, and a directional screen, The light source control unit acquires parallax identification information to identify the position of the parallax image to be displayed, The light source at the position corresponding to the parallax identification information projects illumination light onto the image display unit via the illumination optical system. The image display unit performs an illumination step in which it displays the parallax image corresponding to the parallax identification information using the illumination light, The aforementioned projection optical system, The light source image corresponding to the aforementioned illumination light is made into parallel light, The parallax image corresponding to the parallax identification information is formed from the light source image, A projection step of projecting the disparity image corresponding to the imaged disparity identification information onto the directional screen, The directional screen is used to display the parallax image corresponding to the parallax identification information, with the parallax having directionality. The display of the parallax image with a predetermined number of parallaxes is repeated until the number of frames in the displayed video is reached. 3D display method.

Images