JPH08327947A - Stereoscopic display device using diffraction grating - Google Patents

Abstract

PURPOSE: To make it possible to easily produce diffraction gratings by recording a line light source on a hologram dry plate every time a mask position with respect to this hologram dry plate is changed. CONSTITUTION: The diffraction gratings or unidirectionally directive screens are formed by using the hologram dry plate 10' having the shape and size meeting the shape and size of a screen for observing stereoscopic images. In such a case, the position of the mask 12 is shifted at every set of plural dots and the line light source 14 is recorded and developed on the hologram dry plate 10' every these plural dots. Then, the diffraction gratings of the holograms different for every respective dots of the set of the plural dots. LCD panels are arranged in front of these diffraction gratings or screens and are irradiated with illumination light from behind. The images of the LCD panels through the diffraction gratings of one kind of the holograms are observed at an observation point according to it. Then, the three-dimensional images are observed at the observation point if the images for stereoscopic display are displayed on the LCD panels.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional display device using a diffraction grating, and more particularly to a three-dimensional image display device for CAD in the design field of architecture, civil engineering, etc., a three-dimensional image display device in the medical field, and a three-dimensional image of an arcade game machine. The present invention relates to a three-dimensional display device (real-time three-dimensional display) that allows an observer to stereoscopically recognize an image using a diffraction grating, such as a display device and a home-use three-dimensional television.

[0002]

2. Description of the Related Art One example of a stereoscopic display device of this type is disclosed in, for example, Japanese Patent Application Laid-Open No. 4-1992.
No. 311916 [G02B 27/22, 27/42]
Is disclosed in. In this conventional technique, in a display configured by arranging minute diffraction gratings (gratings) on the surface of a substrate for each dot, the diffraction grating forming the dots is configured by a set of a plurality of lines that are parallel-moved curves. A three-dimensional display device in which an image with parallax is created by the diffraction grating by arranging a light blocking means on the incident side of the illumination light of the diffraction grating or the emission side of the diffracted light.

[0003]

In the above-mentioned prior art,
Since the diffraction grating is created by the electron beam exposure device,
It takes time to manufacture a diffraction grating. That is, in the conventional technique, a stereoscopic image can be observed even if the same diffraction grating is used for each dot in the case of a small screen size, but if the same diffraction grating is used for each dot in the case of a large screen, the stereoscopic image can be observed. Therefore, in the case of a large screen, it is necessary to calculate the direction Ω of the diffraction grating and the pitch d of the diffraction grating for each dot so as to match it, and draw with the electron beam apparatus according to the calculation results. Therefore, the conventional technique has a problem that it takes a huge amount of time to form a diffraction grating.

Therefore, a main object of the present invention is to provide a method for easily manufacturing a diffraction grating. Another object of the present invention is to provide a stereoscopic display device using such a novel diffraction grating.

[0005]

According to the present invention, (a) a hologram dry plate having a size suitable for a screen is prepared, and (b) a mask means is used for each one of a plurality of dots for one dot. Selectively set the light transmission state, (c) using the mask means, the reference light and the point light source is recorded on the hologram dry plate by irradiating the linear dry light source on the hologram dry plate, (d) Repeat steps (b) and (c) for all of the dots, and
(e) A method of manufacturing a diffraction grating, which comprises developing a hologram dry plate.

[0006]

The linear light source is recorded on the hologram dry plate each time the mask position with respect to the hologram dry plate is changed. Therefore, different holograms (diffraction gratings) are formed at different positions. A three-dimensional display device is configured using the diffraction grating and the spatial light modulator formed in this way. That is, by arranging a spatial light modulator such as an LCD panel in front of the diffraction grating and irradiating the diffraction grating with illumination light from behind or in front of the diffraction grating, a three-dimensional observation point is provided in front of the spatial light modulator. You can observe the image.

[0007]

According to the present invention, since the hologram is used, the diffraction grating can be manufactured extremely easily and quickly as compared with the prior art. Therefore, it can contribute to the practical application of a stereoscopic display device using such a diffraction grating. The above-mentioned objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of the embodiments with reference to the drawings.

[0008]

1 and 2 are schematic views showing an embodiment of the present invention for manufacturing a diffraction grating used in a stereoscopic display device. In this embodiment, a hologram dry plate 10 'having a shape and a size adapted to the shape and size of a screen for observing a stereoscopic image is used to form a diffraction grating or a unidirectional directional screen (hereinafter, simply referred to as "screen"). There are things.)

A mask 12 is provided on the front surface of the hologram dry plate 10 '.
To adhere. As shown in FIG. 3, this mask 12 selectively sets one of the plurality of dots (in this embodiment, four dots in the upper, lower, left, and right) groups to a light-transmitting state, and It has a large number of apertures 12a capable of setting the dots in the shaded state. Each aperture 12a, in one example, is approximately 0.31 mm × 0.31.
mm square.

A linear light source 14 is arranged in front of a hologram dry plate 10 'in which a mask 12 is closely attached to the front surface so that light is directed to the hologram dry plate 10'. The distance between the line light source 14 and the hologram dry plate 10 'correlates with the distance from the screen of the viewpoint for observing a stereoscopic image. An example of the line light source 14 is shown in FIG. The linear light source 14 uses a laser beam 16 such as a He—Ne laser.
6 is incident on the cylindrical lens 18. Since the axis of the cylindrical lens 18 is in the horizontal direction, the laser beam 18 spreads in the vertical direction at one point in the horizontal direction.
Then, the light diffused in the vertical direction through the cylindrical lens 18 enters the glass rod 20 whose axis is in the vertical direction. The glass rod 20 diffuses the incident light in the horizontal direction. Therefore, this glass rod 20 becomes a linear light source.
That is, the point light sources are continuously arranged over the entire length of the glass rod 20 in the axial direction. The light transmitted through the glass rod 20 is applied to the hologram dry plate 10 ′ shown in FIGS. 1 and 2, but when the screen is reproduced, the viewpoint is vertical, that is, at the position where the glass rod 20 was at the time of producing the diffraction grating. The light from each dot must be diffused in the vertical direction in order to secure the viewing area of. Therefore, in FIG. 4, the lenticular plate 22 is arranged behind the glass rod 20 to diffuse light when the diffraction grating is manufactured. That is, the light transmitted through the glass rod 20 and diffused in the horizontal direction is incident on the flat plate surface of the lenticular plate 22 whose axis is in the horizontal direction. Therefore, the light further diffused in the vertical direction is output from the convex surface of the lenticular plate 22.

Thus, the linear light source 14 shown in FIG.
Is a vertical linear light diffused horizontally,
It becomes a line light source. Then, as shown in FIG. 1 and FIG.
From the front of the hologram plate 10 ', the hologram plate 1
At an incident angle of about 45 ° with respect to the 0 ′ plane, the reference light 24 is
Irradiate with the linear light source 14. However, the incident angle of the reference light 24 is determined depending on the angle of the illumination light described below, and can be arbitrarily changed according to the angle of the illumination light. In this way, the hologram dry plate 10 ′ is exposed through the mask 12 by the line light source 14 and the reference light 24.
That is, the linear light source 14 is recorded on the hologram dry plate 10 '. The line light source 14 is nothing but a three-dimensional object arranged in space. At this time, the line light source 14 is not recorded on the portion of the hologram dry plate 10 ′ covered by the light shielding portion of the mask 12.

Here, the hologram dry plate 10 'is developed to form the diffraction grating or screen 10 shown in FIGS. Then, as shown in FIGS. 5 and 6, from the rear of the screen 10 to the surface of the screen 10 approximately 4
When the screen 10 is viewed at the image forming point 28 of the linear light source 14 when the conjugate light 26 is irradiated at an incident angle of 5 ° (this angle and direction are determined by the angle and direction of the reference light 24 described above). Luminescence is observed on the entire surface of the screen 10. This is because the real image of the hologram is projected on the image forming point 28. A two-dimensional image can be displayed by modulating the surface emission of the screen 10 using a spatial light modulator, such as a liquid crystal display panel (LCD panel). Such a two-dimensional image is observed only at the position of the linear light source 14 arranged at the time of recording on the hologram dry plate 10 '.

Therefore, using the mask 12 shown in FIG. 3, the recording portion of the linear light source 14 on the hologram dry plate 10 'and the position of the line light source 14 to be recorded with respect to the hologram dry plate 10' are changed for each exposure. Then, after exposing all the dots included in the set of dots, the hologram dry plate 1
By developing 0 ', it is possible to make a screen 10 having four viewing points. That is, the mask 12
The hologram dry plate 10 is provided by shifting the positions of the line light source 14 and the line light source 14.
It is possible to obtain the screen 10 having the number of viewpoint positions corresponding to the number of exposures by repeatedly exposing and developing the image.

The screen 10 is used to form the stereoscopic display device 30 shown in FIG. The stereoscopic display device 30 is a transmissive display, and an LCD panel 32, which is an example of a spatial light modulator, is arranged in front of the screen 10.
In this embodiment, the number of dots on the LCD panel 32 is, for example, 640 × 480, and each dot size is 0.31 m.
It is m × 0.31 mm. Also, on the screen 10,
307,200 corresponding to the number of dots on the LCD panel 32
Holograms were formed. Therefore, screen 1
The size of each dot on 0 is the same as the size of each dot on the LCD panel 32.

Then, a light source 32 such as a He-Ne laser is arranged behind the screen 10, and the light source 32
The illumination light 34 is emitted from the rear surface of the screen 10.
Since many holograms are recorded on the screen 10 as described above, the light transmitted through the screen 10 is dispersed in the vertical direction but in the horizontal direction only in a certain direction. Therefore, at the observation point 36, a stereogram that is parallel only in the horizontal direction is created.

Explaining in more detail, the LCD shown in FIG.
In the first row of panel 32, the hologram is (1,
1) Placed at the position indicated by _{# 1} . Then, the hologram diffracts light to the first observation point as shown by the alternate long and short dash line in FIG. The hologram at the next dot position (1, 2) _{# 1} also diffracts the transmitted light to the first observation point. Also,
In the first row of the LCD panel 32, the hologram arranged at the dot position (1,1) _{# 2} diffracts the transmitted light to the second observation point. The hologram at the next dot position (2,2) _{# 2} also diffracts the transmitted light to the second observation point. As for the first line, the hologram at the dot position with the subscript _{# 1} is added to the first observation point with the subscript.
The hologram at the dot position marked with _{# 2} diffracts the transmitted light at the second observation point.

In the second row of LCD panel 32,
Similarly, the hologram at the dot position with the suffix _{# 3} diffracts the transmitted light at the third observation point, and the hologram at the dot position with the suffix _{# 4} diffracts the transmitted light at the fourth observation point.
However, although discontinuity of observable dots causes a gap between the dots, this gap does not cause an unnatural image because the dots are small.

Therefore, the stereoscopic display device 30 shown in FIG.
At observation points 36 _{# 1} and 36 _{# 2} or observation point 3
By placing the left and right eyes at 6 _{# 3} and 36 _{# 4} , a stereoscopic image can be observed. For example,
By displaying an image as shown in FIG. 10 on the LCD panel 32 (not shown in FIG. 9), each observation point 3
As shown in FIG. 9, images of "A", "B", "C" and "D" can be observed at 6 _{# 1} , 36 _{# 2} , 36 _{# 3} and 36 _{# 4} . Therefore, when an image on which the right-eye image and the left-eye image are superimposed is displayed on the LCD panel 32, only the right-eye image is observed by the right eye and only the left-eye image is observed by the left eye, so that the stereoscopic image is displayed. You can observe it.

In the embodiment of FIG. 9, since the hologram of the screen 10 is formed so as to form the _four observation points 36 _{# 1} , 36 _{# 2} , 36 _{# 3} and 36 _{# 4} , the resolution is 200 ×. It became 160x4. Also, screen 1
At 0, different holograms may be formed for each group of eight dots so that the image on the LCD panel 32 is individually observed by eight observation points as shown in FIG. In this case, set the LCD panel 32 to 45 °
It can be handled simply by tilting it.

In the above-mentioned embodiment, the transmissive stereoscopic display device 3 is used.
It was 0. However, it goes without saying that the present invention can be applied to the reflection type as well. FIG. 12 is an illustrative view showing a reflective stereoscopic display device 30 which is another embodiment of the present invention. In this embodiment, a reflective screen 10 is used as the diffraction grating or screen. Then, an LCD panel 32 as a spatial light modulation element is arranged in front of the screen 10, and conjugate light, that is, illumination light 34 is emitted from the light source 32 from the front thereof. However, the irradiation position and direction of the light source 34 are set in relation to the reference light used when forming the hologram on the screen 10, as in the above-described embodiment. Also in this embodiment, only the image of a specific dot on the LCD panel 32 can be observed at the observation point 36 due to the action of the diffraction grating or the hologram formed on the screen 10.

FIGS. 13 and 14 are schematic views showing another embodiment of the present invention for manufacturing the screen 10 used in the embodiment of FIG. In this embodiment, the hologram dry plate 10
The mask 12 is brought into close contact with the rear surface of ′. As shown in FIG. 3, the mask 12 can selectively set any one of the plurality of dots in the light transmitting state and set the other dots in the light shielding state for each set of the plurality of dots. It has a large number of apertures 12a. Then, for example, the line light source 14 described with reference to FIG. 4 is arranged behind the hologram dry plate 10 'in which the mask 12 is closely arranged on the rear surface so that the light is directed to the hologram dry plate 10'.

Then, as shown in FIGS. 13 and 14, the reference beam 24 is incident from the front of the hologram dry plate 10 'at an incident angle of about 45 ° with respect to the surface of the hologram dry plate 10'.
Is irradiated. However, the incident angle of the reference light 24 can be arbitrarily changed. In this way, the linear light source 14 and the reference light 2
4, and the hologram dry plate 1 through the mask 12
0'is exposed. That is, the linear light source 14 is recorded on the hologram dry plate 10 '.

Here, the hologram dry plate 10 'is developed and the diffraction grating or screen 1 shown in FIGS.
Make 0. Then, as shown in FIG. 15 and FIG.
When the conjugate light 26 is applied to the surface of the screen 10 from the front of the screen 10 at an incident angle determined by the angle and direction of the reference light 24, when the screen 10 is viewed at the image forming point 28 of the linear light source 14 described above, Light emission is observed on the entire surface of the screen 10. This is because the real image of the hologram is projected on the image forming point 28. Then, by modulating the surface emission of the screen 10 using, for example, the LCD panel 32 described above,
Two-dimensional images can be displayed. Such a two-dimensional image is observed only at the position of the linear light source 14 arranged at the time of recording on the hologram dry plate 10 '.

Therefore, by using the mask 12 shown in FIG. 3, the recording portion of the linear light source 14 on the hologram dry plate 10 'and the position of the line light source 14 to be recorded with respect to the hologram dry plate 10' are changed for each exposure. Then, after exposing all the dots included in the set of dots, the hologram dry plate 1
By developing 0 ', it is possible to make a screen 10 having four viewing points. That is, the mask 12
The hologram dry plate 10 is provided by shifting the positions of the line light source 14 and the line light source 14.
It is possible to obtain the screen 10 having the number of viewpoint positions corresponding to the number of exposures by repeatedly exposing and developing the image.

It is needless to say that the hologram diffraction grating for the eight observation points shown in FIG. 11 can be formed also in this embodiment. Further, as shown in FIGS. 17 and 18, by limiting the length of the linear light sources 14a and 14b recorded on the hologram dry plate through the mask, different two-dimensional images can be observed above and below. The screen 10 can also be manufactured. By using such a screen 10, it is possible to display a three-dimensional image having parallax not only in the horizontal direction but also in the vertical direction.

Further, as shown in FIG. 19, if a hologram as described above is formed for each RGB dot, a full-color stereoscopic image can be displayed by a color LCD panel or the like. Further, in the above embodiment, the invisible area d is provided between the observation points A and B shown in FIG.
Exists. Therefore, in order to make this invisible region as small as possible, as shown in FIG. 20, each observation point A, B,
For C and D, a plurality of observation points A1 to A3 and B1 to
B3, C1-C3 and D1-D3 are formed. For that purpose, for example, multiple exposure may be performed when the linear light source is recorded on the hologram dry plate 10 'using the mask of FIG.
That is, with respect to one mask position, the position of the linear light source with respect to the hologram dry plate 10 ′ may be changed for each exposure and exposure may be performed a plurality of times (four times in this embodiment). By doing so, the same two-dimensional image can be observed at a plurality of observation points, for example, A1 to A3.

For each of the observation points A, B, C and D, the method of FIG. 21 may be used to form a plurality of observation points. That is, in this embodiment, the number of observation points is increased by using Expression 1.

[0028]

## EQU1 ## sin i + sin j = λ / p i: angle of illumination light j: angle of diffracted light λ: wavelength of light p: grating interval The number 1 changes the angle of incident light with respect to the same diffraction grating. If so, the angle of the diffracted light also changes. Therefore, as shown in FIG. 21, it means that the same two-dimensional image can be observed at different observation points by reproducing the screen with a plurality of illumination lights having different angles. That is, the number of observation points can be increased by irradiating and reproducing the screen with a plurality of illumination lights having different angles.

Furthermore, by sequentially reproducing the screen using illumination light having different angles with time, and synchronizing the change of the angle of the illumination light and the switching of the display image of the spatial light modulator and the LCD panel, For example, an n × 4 parallax image can be observed using a screen having four observation points. However, n is the number of times that the angle of the illumination light and the display image are synchronously changed in one frame, for example. In this case, it is necessary to constrain the drawing speed of the spatial light modulator by n times that in the normal case.

[Brief description of drawings]

FIG. 1 is a schematic side view showing an embodiment of the present invention for manufacturing a transmissive screen.

FIG. 2 is a schematic top view showing an embodiment of manufacturing a transmissive screen.

FIG. 3 is an illustrative view showing one example of a mask used in this embodiment.

FIG. 4 is an illustrative view showing one example of a line light source used in this embodiment.

FIG. 5 is a side view showing that a two-dimensional image can be observed by the screen created in FIGS. 1 and 2.

FIG. 6 is a schematic top view showing that a two-dimensional image can be observed with the screens created in FIGS. 1 and 2.

FIG. 7 is a side view solution diagram showing a transmissive stereoscopic display device of one embodiment of the present invention configured by using the screens produced in FIGS. 1 and 2.

FIG. 8 is an illustrative view showing that different two-dimensional images can be observed at different observation points in this example.

FIG. 9 is an illustrative view showing that a three-dimensional image can be observed in this example.

10 is an illustrative view showing one example of a display image on the LCD panel of FIG. 9. FIG.

FIG. 11 is an illustrative view showing a different arrangement of screens.

FIG. 12 is a schematic side view showing a reflective stereoscopic display device according to another embodiment of the present invention, which is configured using a reflective screen.

FIG. 13 is a side view diagram showing another embodiment of the present invention for producing a reflection type screen.

FIG. 14 is a schematic top view of this example of making a reflective screen.

FIG. 15 is a side view illustrative view showing that a two-dimensional image can be observed by the screen created in FIGS. 13 and 14.

FIG. 16 is a schematic top view showing that a two-dimensional image can be observed with the screens created in FIGS. 13 and 14.

FIG. 17 is a side view diagram showing a screen on which different two-dimensional images can be observed at the top and bottom.

FIG. 18 is a schematic top view showing a screen on which different two-dimensional images can be observed at the top and bottom.

FIG. 19 is an illustrative view showing a screen capable of full-color display.

FIG. 20 is an illustrative view showing one example of a method for making it possible to observe the same two-dimensional image at a plurality of observation points.

FIG. 21 is an illustrative view showing another example of the method for enabling the same two-dimensional image to be observed at a plurality of observation points.

[Explanation of symbols]

 10 ... Screen (diffraction grating) 10 '... Hologram dry plate 12 ... Mask 14 ... Line light source 24 ... Reference light 26 ... Illumination light (conjugate light) 28 ... Imaging point 32 ... LCD panel 36 ... Observation point

Claims (9)

[Claims] 1. (a) A hologram dry plate having a size suitable for a screen is prepared, and (b) a light transmission state is selectively set for any one of a plurality of dots by a mask means. Then, (c) using the mask means, recording the linear light source on the hologram dry plate by irradiating the hologram dry plate with a line light source in which a reference light and a point light source are linearly arranged, (d) The above steps for all of the multiple dots
A method of manufacturing a diffraction grating, wherein (b) and (c) are repeated, and (e) the hologram dry plate is developed. 2. A stereoscopic display device comprising a diffraction grating manufactured by the method according to claim 1, and a spatial light modulator for modulating transmitted light or reflected light of the diffraction grating. 3. The illumination light irradiating means for irradiating the illumination light correlated with the reference light from the rear side of the diffraction grating, and the spatial light modulating means is arranged in front of the diffraction grating. Stereoscopic display device. 4. The illumination light irradiating means for irradiating the illumination light correlated with the reference light from the front side of the diffraction grating, and the spatial light modulating means is arranged in front of the diffraction grating. Stereoscopic display device. 5. The stereoscopic display device according to claim 3, wherein the illumination light irradiation means irradiates the diffraction light with the illumination light at different angles. 6. The manufacturing method according to claim 1, wherein in the step (c), linear light sources having different angles with respect to the hologram dry plate are recorded in multiple for one dot. 7. The manufacturing method according to claim 1, wherein in the step (c), a plurality of line light sources arranged in a vertical direction with respect to one dot are recorded on the hologram dry plate. 8. A set of dots each comprising:
A stereoscopic display device comprising: a diffraction grating having different holograms formed on a plurality of dots; and a spatial light modulator for modulating transmitted light or reflected light of the diffraction grating. 9. The stereoscopic display device according to claim 8, wherein the plurality of dots are RGB dots.