JP2513403B2 - Projection type stereoscopic display device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type stereoscopic display device which allows an observer to observe a stereoscopic image without wearing special glasses.

[0002]

2. Description of the Related Art Conventionally, as a device for displaying a stereoscopic image or a three-dimensional image, a device for presenting image information having binocular parallax to the right eye and the left eye, and a cross-sectional image of an object synchronized with the movement of a moving screen. Then, a device for sequentially displaying and a device using a hologram have been proposed. In particular, a projection-type stereoscopic display device capable of projecting and displaying a binocular parallax image and observing a stereoscopic image on a large screen has a more realistic stereoscopic effect due to the presence of the large-screen display as well as the stereoscopic effect of the image. Images can be obtained. This projection type stereoscopic display device uses a device for an observer to observe a stereoscopic image by wearing special glasses such as polarizing glasses and liquid crystal shutter glasses, and a stereoscopic image using a special screen such as a lenticular screen. There is a device to observe. The latter has an advantage that an observer can observe a stereoscopic image without wearing special glasses.

FIG. 3 is a plan view for explaining the display principle of a conventional projection type stereoscopic display device using a lenticular screen. The conventional projection type stereoscopic display device 31 includes a stereoscopic image projection system 32 and a lenticular screen 33. The lenticular screen 33 has a structure in which a large number of elongated cylindrical lenses 34 are arranged. The focal plane of each cylindrical lens 34 is used as a projection display surface, and the stereoscopic image projection system 32 projects and displays a stereoscopic image 35 thereon. The stereoscopic image 35 is obtained by dividing and extracting a right-eye image 36 and a left-eye image 37 having binocular disparity information into striped images that are long in the vertical direction of the screen according to the number of cylindrical lenses 34, and alternately extracting them. It has been created by rearranging. When the stereoscopic image 35 is projected and displayed, as shown in FIG. 3, the stereoscopic image projection system 32 is arranged so that the right-eye image 36 and the left-eye image 37 are displayed at positions determined by the positions of the respective cylindrical lenses 34 and the observer 38. Adjust.
When the observer 38 observes such a projection-type stereoscopic display device 31, the eyes of the observer 38 from the right eye 39 and the left eye 40 are incident on the lenticular screen 33 at different angles, so that the observer 38 can see the right eye. The eye 39 sees only the right-eye image 36, and the left eye 40 sees only the left-eye image 37. The observer 38 can observe an image having a stereoscopic effect by fusing these images.

In the conventional projection type stereoscopic display device using such a lenticular screen, there are drawbacks that the observation range in which stereoscopic vision is possible is discrete in the front, rear, left and right directions, and the position of the observer is limited. . Here, the front-back direction is a direction orthogonal to the lenticular screen, and the left-right direction is a direction parallel to the lenticular screen. Generally, this observation range is about 200 to 400 mm in the front-rear direction, and there are discrete ranges of about 60 to 65 mm in the left-right direction. When the observer moves back and forth or left and right beyond this observation range, the right eye image and the left eye image do not enter the right eye and left eye independently, and the observer sees the whole image or a part of the image. Therefore, the image of the opposite eye is observed, and stereoscopic vision becomes impossible. Since the observation range in the left-right direction is narrower than that in the front-rear direction, enlarging the observation range in the left-right direction has been a problem of the projection type stereoscopic display device using the lenticular screen.

In order to expand the observation range in the left-right direction, when the position of the observer moves, the amount of movement is detected, and the stereoscopic image projected and displayed is moved to the left or right according to the amount of movement. It is known that it may be controlled so that the eyes of the above observe the corresponding image. For example, Japanese Patent Laid-Open No. 1-
See Japanese Patent No. 107247. Therefore, a projection-type stereoscopic display device has been proposed in which the stereoscopic image projection system is moved left and right on a moving stage to expand the observation range. For example, the magazine "199
1 year, Television Society Technical Report Vol. 15, No. 56, pp. 7-12 "," Paper Study on Wide-Band Stereoscopic Display System Using View Tracking ". FIG. 4 is a diagram showing a conventional example of a projection type stereoscopic display device. The projection type stereoscopic display device 41 of this conventional example includes a stereoscopic image projection system 32, a lenticular screen 33, and a moving stage 42. Here, a liquid crystal projector is used as the stereoscopic image projection system 32. The three-dimensional image projection system 32 is moved using the moving stage 42 according to the movement of the observer 38, and the three-dimensional image 35 to be projected and displayed is moved left and right.

[0006]

In the conventional projection type stereoscopic display device 41 shown in FIG. 4, since the stereoscopic image projection system is moved by the moving stage 42, the device is large and very heavy. Furthermore, in order to move the stereoscopic image projection system 32 of generally several tens of kg according to the position of the observer 38, the response performance and the load on the moving stage 42 pose a problem.

An object of the present invention is to improve the response performance by using a simple optical system in a projection type stereoscopic display device capable of moving a stereoscopic image according to the position of the observer and expanding the observation range of the observer. It is an object of the present invention to provide a projection-type stereoscopic display device which is excellent in lightness and reduces the load on the moving stage.

[0008]

The present invention comprises a stereoscopic image projection system including at least a light source, a liquid crystal display element and a projection lens, and a lenticular screen, and detects the position of an observer to detect the position of the observer. in the projection-type stereoscopic display apparatus that controls movement of the three-dimensional image projected in the optical path between the liquid crystal display element and the projection lens of the stereoscopic image projection system, between the liquid crystal display element and the projection lens
And at least two prisms that move by a distance set according to the movement of the observation position of the observer are arranged while keeping the optical path length of

[0009]

According to the above configuration of the present invention, when at least two prisms are arranged in the optical path between the liquid crystal display element and the projection lens, the refraction of the light of the prism causes the liquid crystal display element of the projection lens to move. The optical position translates. By changing the relative positions of at least two prisms, it is possible to change the amount of parallel movement of the liquid crystal display element while the stereoscopic image on the screen is in focus.
If the prism is controlled to move by a distance set according to the movement of the observer's observation position, the stereoscopic image projected and displayed will be left and right so that the left and right eyes of the observer always observe the corresponding images. Will be moved to. Therefore,
It is possible to expand the observation range in the left-right direction of the observer. The arrangement of the prism does not require a large space and the device does not become large. Further, since the prism is lightweight, the driving load of the moving stage is light and the response can be made faster than in the conventional case.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view of a projection type stereoscopic display device showing an embodiment of the present invention. This projection type stereoscopic display device 1
Is composed of a stereoscopic image projection system 2 and a lenticular screen 3. Further, the stereoscopic image projection system 2 includes a liquid crystal display element 5, a light source 4 for illuminating the liquid crystal display element 5,
The image displayed on the liquid crystal display element 5 is displayed on the lenticular screen 3
A projection lens 6 for enlarging and projecting to obtain a stereoscopic image 9;
Two prisms 7 and 8 for translating the stereoscopic image 9
Consists of

Next, the principle of the projection type stereoscopic display device according to the present invention having the structure shown in FIG. 1 will be described with reference to FIGS. FIG. 2 is a diagram for explaining the principle of the projection type stereoscopic display device of the present invention.

FIGS. 2A to 2C are partial plan views of the projection type stereoscopic display device of FIG. 1, showing a part between the liquid crystal display element 5 and the projection lens 6. 2A to 2C, the light flux transmitted through the liquid crystal display element 5 is reflected by the prism 7
After being refracted by the prism 8, the light enters the projection lens 6. The prism 7 and the prism 8 are right-angle prisms, and the same prism is used. The light entrance surface of the prism 7 and the light exit surface of the prism 8 are arranged on a surface perpendicular to the optical axis 20 of the projection lens 8. Optical axis 20 of projection lens 6
Is refracted and bent by the prisms 7 and 8 as shown in the figure. However, in such an arrangement, the optical axes before and after the prism 7 and the prism 8 are parallel. Here, the optical axis 20 is formed by the prism 7 and the prism 8.
Of the prism 7 and the prism 8 is determined by the refractive indices of the prisms 7 and 8, the apex angle, and the distance between them.

In FIG. 2A, the prism 7 and the prism 8 are arranged at a certain set position described later and with a gap therebetween. The projection lens 6 is arranged so that its optical axis 20 passes through the center 25 of the liquid crystal display element. The projection lens 6 is focused so that the image displayed on the liquid crystal display element 5 is projected on the lenticular screen 3 shown in FIG. At this time, the lenticular screen 3 is arranged so that its center coincides with the center of the projected stereoscopic image 9 and the display principle of the projection type stereoscopic display device of FIG. 3 is satisfied. The above arrangement of the constituent elements is set as a reference position.

FIG. 2B shows a case where the prism 8 is moved in parallel so that the prism 7 and the prism 8 are closer to each other than the reference position of FIG. 2A. As is clear from the figure, when the distance between the prism 7 and the prism 8 is shortened, the parallel movement distance of the optical axis 20 is shortened. At this time, the optical axis 20 of the projection lens 6 and the center 25 of the liquid crystal display element do not coincide. That is, the stereoscopic image 9 projected and displayed on the lenticular screen 3 in FIG. 1 moves in parallel. Here, only by moving the prism 8 in a direction parallel to the optical axis 20, the optical path length between the projection lens 6 and the liquid crystal display element 5 is changed, and the stereoscopic image 9 projected and displayed is defocused on the lenticular screen 3. turn into. Therefore, the prism 8 also moves in the direction perpendicular to the optical axis 20,
It is necessary to always move the stereoscopic image 9 on the lenticular screen 3 while keeping it in focus. The amount of movement of the stereoscopic image 9 on the lenticular screen 3 is obtained by multiplying the amount of movement of the optical axis 20 on the liquid crystal display element 5 by the magnification of the projection lens 6.

FIG. 2 (c) shows a case where the prism 8 is moved in parallel so that the prism 7 and the prism 8 are farther from the reference position of FIG. 2 (a). As in FIG. 2B, the optical axis 20 of the projection lens 6 and the center 25 of the liquid crystal display element 25.
Will not match. However, the direction of the parallel movement is opposite to that in the case of FIG. That is, the stereoscopic image 9 projected and displayed on the lenticular screen 3 in FIG. 1 moves in parallel, and the direction thereof is opposite to that in the case of FIG. 2B. The prism 8 always moves while the stereoscopic image 9 is kept in focus on the lenticular screen 3.

As is clear from the above description, when the prism 8 is moved with respect to the prism 7, the three-dimensional image 9 projected and displayed on the lenticular screen 3 can be moved in parallel. It can be controlled by a moving amount of 8. Therefore, if the prism 8 is moved by a distance set according to the movement of the observation position of the observer,
The stereoscopic image 9 projected and displayed always moves to the left and right so that the left and right eyes of the observer observe the corresponding image, and the observation range in the left and right direction of the observer can be expanded. Here, the positions and intervals of the prism 7 and the prism 8 in FIG. 2A described above are determined by the constituent elements when the prism 7 and the prism 8 are maximally moved so as to correspond to the assumed lateral movement amount of the observer. It is set not to contact.
When the prism 7 and the prism 8 come close to each other as shown in FIG. 2B, the prisms should not come into contact with each other.
When they are separated as shown in (c), the prism 8 and the projection lens 6 are prevented from contacting each other. When moving the prism 7, the liquid crystal display element 5 is not contacted. That is, the reference position shown in FIG. 2A is an intermediate position when the prism 7 and the prism 8 are maximally moved.

The prisms 7 and 8 will be described in more detail. Their sizes give a refraction effect to all the light beams which are transmitted through the liquid crystal display element 5 and the projection lens 6 and are projected on the lenticular screen 3. It is necessary to satisfy this condition even when the prism 7 and the prism 8 are maximally moved. Prism 7, 8
As for the material, if a material having a large refractive index is used, the stereoscopic image 9 on the lenticular screen 3 can be largely moved with a small amount of movement. However, if the wavelength dispersion of the refractive index is large, chromatic aberration occurs on the projection screen and stereoscopic vision becomes difficult, so that the wavelength dispersion of the refractive index is small. Regarding the apex angles of the prisms 7 and 8, if the apex angles of the prisms 7 and 8 are large, the stereoscopic image 9 on the lenticular screen 3 can be largely moved with a small amount of movement. However, the prisms 7 and 8
If the apex angle of is extremely large, astigmatism occurs, and the resolution of the stereoscopic image 9 on the lenticular screen 3 decreases. In this case, crosstalk occurs between the right-eye image and the left-eye image, which makes stereoscopic viewing difficult, so the apex angles of the prisms 7 and 8 are not extremely large. However, if the amount of astigmatism is small, the projection lens 6 is focused so as to ensure the resolution in the direction in which the cylindrical lenses of the lenticular screen 3 are arranged (the direction in which the meridional ray that passes through the prism is imaged). Then, the influence becomes small and stereoscopic vision becomes possible.

In the structure shown in FIG. 1, the prisms 7 and 8 are equal right-angle prisms, and the light entrance surface of the prism 7 and the light exit surface of the prism 8 are arranged with respect to the optical axis of the projection lens 6. This is an example of a mode in which the prism 8 is arranged on a vertical surface and is movable, and this will be described more specifically below.

The light source 4, the liquid crystal display element 5, the projection lens 6, the lenticular screen 3, and the prisms 7 and 8 used in the configuration of FIG. 1 are specifically as follows.

As the light source 4, a 250 W metal halide lamp was used. The emitted light is collimated by a parabolic mirror and illuminates the liquid crystal display element 5. Although not shown in the figure, the illumination light is obtained by removing the components of light other than visible light with a cold mirror, an ultraviolet cut filter, or the like.

The liquid crystal display element 5 is one in which liquid crystal is enclosed in two glass substrates provided with transparent electrode films for forming pixels, and although not shown in the drawing, the light input / output surface of the liquid crystal display element is not shown. A polarizing plate is arranged in the pixel, and the voltage applied to each pixel is controlled by the video signal from the video signal processing circuit and the liquid crystal driving circuit. As the liquid crystal, twisted nematic liquid crystal is used, and the change in the state of the liquid crystal due to the voltage applied to each pixel changes the polarization state of the illumination light, and the illumination light is intensity-modulated by the polarizing plate. As a liquid crystal driving method, an active matrix method in which a thin film transistor which is a switching element is formed for each pixel and the liquid crystal is driven is used. The pixel pitch in the horizontal direction is 0.14
The thing of mm was used.

The projection lens 6 magnifies and projects the display image of the liquid crystal display element 5 on the lenticular screen 3 as a stereoscopic image 9. The focus lens and the size of the screen are adjusted so that the focus of the projected image can be adjusted. The one with a zoom mechanism for changing was used. In particular, a projection image with a small distortion is used.

The lenticular screen 3 is composed of an acrylic plate having its surface processed by injection molding so as to have a structure in which a large number of cylindrical lenses are arranged, and a diffusion screen arranged on the focal plane of the cylindrical lenses. The stereoscopic image projection system 2 was arranged and adjusted so that the stereoscopic image 9 was formed on the surface of the diffusion screen. The display surface of the lenticular screen 3 has a diagonal size of 40 inches.
The pitch of the cylindrical lens and the focal length are designed so that the observer can observe a stereoscopic image at a position 2 m away from the lenticular screen 3.

The prisms 7 and 8 are right angle prisms made of BK-7 and having an apex angle of 10 degrees. An antireflection film made of a dielectric multilayer film was applied to the incident surface and the output surface thereof. Although not shown in the drawing, a moving stage driven by a pulse motor is attached to the prism 8 so that the prism 8 can move in a direction parallel to the optical axis of the projection lens 6 and a direction perpendicular thereto.

The observation range in the left-right direction of the observer of the projection type stereoscopic display device 1 according to the present invention, which comprises the above-mentioned components, is as shown below. The distance between the prism 8 and the prism 7 in the optical axis direction should be 0 mm to 20 mm.
When is moved, the amount of parallel movement of the optical axis of the projection lens 6 is
It becomes 1.88 mm. The liquid crystal display element 5 having a pixel pitch of 0.14 mm is used, and the parallel movement amount of the optical axis corresponds to 13.4 pixels. The pixel pitch of the liquid crystal display element 5 is 65 m between the left and right eyes at the observer's position.
Since it corresponds to m, the observation range in the left-right direction of the observer is about 8
It becomes 70 mm. Therefore, the observer can continuously stereoscopically view 435 mm from the center to the left and right.
Here, the method of detecting the position of the observer and controlling the moving stage is the same as in the conventional example, and although not shown in the figure, the position of the observer is determined by image processing using a magnetic sensor, an infrared sensor, or a video camera. Is detected and the amount of movement is calculated by the computer, and then the prism 8 is controlled to move by the moving stage. The amount of movement of the prism 8 is small,
Moreover, since it is lightweight, it can be moved at high speed, and since calculation is also performed instantaneously, real-time control is possible.

As described above, in the embodiments of the present invention, each prism is not necessarily a right angle prism. Further, each prism does not have to be configured by one prism, and prisms made of different materials may be bonded together. Further, not limited to glass, a wedge type container filled with a liquid may be used.

As the light source, a high brightness white light source such as a xenon lamp or a halogen lamp can be used in addition to the metal halide lamp.

As the liquid crystal, in addition to the twisted nematic liquid crystal, super twisted nematic liquid crystal, ferroelectric liquid crystal, polymer-dispersed liquid crystal and other liquid crystal of a type capable of forming an image can be used. Further, the liquid crystal drive system is not limited to the active matrix system, and may be a time-division drive simple matrix system.

The liquid crystal display element is used for monochrome display,
Color display with a built-in color filter, plus red,
The present invention can be applied to any of the color display by displaying the green and blue images in a time division manner. However, in the case of color display with a built-in color filter, it is necessary to arrange the red, green, and blue color filters in one pixel of an image composed of red, green, and blue pixels so as to be aligned in the vertical direction of the image. .

Further, the projection light from the light source is separated into three colors of red, green and blue by a dichroic mirror or a dichroic prism, and a liquid crystal display element is arranged in each optical path.
The same projection type stereoscopic display device can be obtained even when they are combined to perform color display.

[0032]

As described above, according to the present invention,
If at least two prisms are arranged in the optical path between the liquid crystal display element and the projection lens, and the prisms are controlled to move by a distance set according to the movement of the observation position of the observer, the projection display is performed. The left and right eyes of the observer always move to the left and right so as to observe the corresponding image, and the observer's left-right direction observation range can be expanded. The prism does not require a large space, the device does not increase in size, and the prism is light in weight, so the driving load of the moving stage is light and a faster response than before is possible. A projection type stereoscopic display device could be obtained.

[Brief description of drawings]

FIG. 1 is a plan view of a projection type stereoscopic display device showing an embodiment of the present invention.

FIG. 2 is a diagram for explaining the principle of the projection type stereoscopic display device of the present invention.

FIG. 3 is a plan view for explaining a display principle of a conventional projection type stereoscopic display device using a lenticular screen.

FIG. 4 is a diagram showing a conventional example of a projection type stereoscopic display device.

[Explanation of symbols]

 1, 31, 41 Projection-type stereoscopic display device 2,32 Stereoscopic image projection system 3,33 Lenticular screen 4 Light source 5 Liquid crystal display element 6 Projection lens 7,8 Prism 9,35 Stereoscopic image 20 Optical axis 25 Center of liquid crystal display element 34 Cylindrical lens 36 Right eye image 37 Left eye image 38 Observer 39 Right eye 40 Left eye 42 Moving stage

Claims (3)

(57) [Claims] 1. A stereoscopic image projection system including at least a light source, a liquid crystal display element, and a projection lens, and a lenticular screen, which detects a position of an observer and controls movement of a stereoscopic image projected by the stereoscopic image projection system. in the projection-type stereoscopic display apparatus, the optical path between the liquid crystal display element and the projection lens of the stereoscopic image projection system, the liquid crystal
Keep the optical path length between the display element and the projection lens constant.
The projection type stereoscopic display device is characterized in that at least two prisms that move by a set distance according to the movement of the observation position of the observer are arranged. 2. The projection type stereoscopic display according to claim 1, wherein the prism moves in a direction parallel to the optical axis of the projection lens and in a direction perpendicular to the optical axis of the projection lens. apparatus. 3. A position detecting means for detecting the position of the observer, and a calculating means for calculating the amount of movement of the observer based on the detected position from the position detecting means, based on the calculated amount of movement. 3. The projection type stereoscopic display device according to claim 2, wherein the movement of the prism is controlled by a lever.