JP2003215498A - Display device and display method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin type display device which eliminates the tiredness of eyes and sense of discomfort and is suitable for displaying of stereoscopic image. <P>SOLUTION: A waveguide substrate 1 is provided with a plurality of optical diffusion plates 2 capable of controlling opacity by voltage impression to the substrate in parallel therewith and these optical diffusion plates 2 are irradiated with a laser beam 14 emitted in a direction perpendicular to the substrate 1 from the substrate by an optical switch 8. Projection positions are changed in a depth direction by controlling the opacity of the respective diffusion plates 2. For example, polymer dispersion type liquid crystals are used as the diffusion plates 2 and, for example, ferroelectric liquid crystals are used as the optical switch 8. The diffusion plates 2 drive pixels like an active matrix by each of the pixels. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device and a display method, and is particularly suitable for displaying a stereoscopic image.

[0002]

2. Description of the Related Art One of conventional stereoscopic displays is one using glasses. In this stereoscopic display, an image for the left eye and an image for the right eye are separated by glasses to obtain a stereoscopic effect by binocular parallax. Meanwhile, recently
A method for obtaining a three-dimensional effect by combining two screens has been proposed (Japanese Patent No. 3022558). This method attempts to change the sense of depth by changing the ratio of the light intensity (luminance) of the two screens.

[0003]

However, in the above-mentioned stereoscopic display using glasses, the same sense of perspective is perceived by the eye lens, whether it is supposed to be near or conversely far away. Given that, it is necessary to focus the eye on the display surface. For this reason, it is different from the reality, and there is a drawback that the eyes feel tired when viewed for a long time.

On the other hand, the method of obtaining a stereoscopic effect by combining the two screens has a drawback that the display becomes thick due to the structure of combining the two screens.

Therefore, the problem to be solved by the present invention is to eliminate the gap between the focal position of the eye and the image, thereby greatly reducing the feeling of fatigue and discomfort in the eye, and displaying a good stereoscopic image. It is to provide a display device and a display method capable of performing the display.

Another problem to be solved by the present invention is
An object of the present invention is to provide a display device and a display method that can be made thinner.

[0007]

In order to solve the above-mentioned problems, the first invention of the present invention is configured so that the position where the image to be displayed is projected can be changed in the depth direction when viewed from the observation position. The display device is characterized by being provided.

A second invention of the present invention has a plurality of projection plates and displays an image by irradiating the plurality of projection plates with light having directivity according to an image to be displayed. Is a display device.

Here, the directional light is normally emitted from the back side of the plurality of projection plates when viewed from the observation position. The plurality of projection plates typically have a flat plate shape, but do not necessarily have to have a flat plate shape, and may have a plate shape in which a part or all of them are curved depending on the application. The plurality of projection plates are typically provided in parallel with each other, but may not necessarily be provided in parallel depending on the application. As the projection plate, a plate whose opacity to directional light can be electrically controlled, for example, is used. The projection plate is, for example, a light diffusing plate, and more specifically, a light diffusing plate whose opacity to directional light is, for example, electrically controllable. The opacity of the light diffusing plate can control the degree of scattering of directional light. As the light diffusing plate, basically any one may be used as long as it can control the opacity by electrically changing the refractive index. The polymer dispersed liquid crystal (PD) that can control the opacity by changing the refractive index by
In addition to those using various liquid crystals such as LC),
For example, a non-linear optical material such as iNbO ₃ may be used. Light having directivity is typically laser light from, for example, a semiconductor laser, but it is not always necessary to use laser light, and for example, the emission direction of light emitted from a light emitting diode or a lamp light source is limited to a narrow range. It may have a directivity. Light having directivity is introduced by, for example, arranging a waveguide on the back side of a plurality of projection plates and introducing it from one end face thereof, and extracting this light to the outside of the waveguide by an optical switch provided on the surface of the waveguide. Irradiate multiple projection plates. In this case, typically, the light extracted by the optical switch to the outside of the waveguide is reflected by the oblique reflection plate in the direction perpendicular to the waveguide and is applied to the plurality of projection plates. Further, for example, the opacity of the projection plate or the light diffusion plate for each pixel may be controlled to drive the projection plate or the light diffusion plate for each pixel by active matrix driving. Although various types of optical switches can be used, for example, a ferroelectric liquid crystal (Ferroelectric Liquid) capable of controlling transmission and non-transmission of light by applying a voltage.
Crystal, FLC) is used. When it is desired to obtain a sufficient sense of depth in the displayed image, it is preferable that a lens for forming an image projected on at least one of the plurality of projection plates is provided on the plurality of projection plates. In contrast, it is provided on the observation position side. This lens is typically provided for each pixel. The display device may display a color image or a monochrome image.

A third invention of the present invention is a display method characterized in that an image is displayed by irradiating a plurality of projection plates with light having directivity according to the image to be displayed. .

In the third invention of the present invention, what has been described in connection with the second invention is established unless the property is violated.

According to the present invention configured as described above, when a plurality of projection plates are irradiated with light having directivity according to an image to be displayed, the light does not spread due to the directivity. It is possible to reach the plate and project the image only on a particular projection plate depending on its opacity. this is,
This means that the projection position of the image can be changed in the depth direction.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. In all the drawings of the embodiments, the same or corresponding parts are designated by the same reference numerals. In the first embodiment of the present invention, a color display in which a light diffusing plate capable of controlling opacity with a voltage and a minute lens are combined in order to obtain a sense of depth will be described.
The overall structure of this color display is shown in FIG.

As shown in FIG. 1, in this color display, for example, a plurality of light diffusing plates 2 are mutually predetermined in parallel with the rectangular flat plate-shaped waveguide substrate 1 and at a predetermined distance from the waveguide substrate 1. It is provided a distance away. The number of these light diffusion plates 2 is determined as necessary,
In FIG. 1, a case where there are three light diffusion plates 2 is shown as an example. The light diffusion plate 2 is, for example, a PDLC whose opacity can be controlled by applying a voltage.
Is used. Adjacent to one end face of the waveguide substrate 1,
A set of three semiconductor lasers, that is, a semiconductor laser 3 for red (R), a semiconductor laser 4 for green (G), and a semiconductor laser 5 for blue (B) corresponds to the number of pixels in the direction of this side. It is only arranged. Here, as the red semiconductor laser 3, for example, an AlGaInP-based semiconductor laser is used.
The semiconductor laser 4 for green is, for example, a ZnSe-based semiconductor laser, and the semiconductor laser 5 for blue is, for example, G.
An aN semiconductor laser is used. Although illustration is omitted,
These semiconductor lasers 3, 4, 5 are provided between the semiconductor lasers 3, 4, 5 and the end face of the one side of the waveguide substrate 1.
Condensing lenses for converging the laser light emitted from the laser light 5 on their end faces are respectively provided. On the other hand, on the outermost light diffusing plate 2, minute lenses 6 are provided in a two-dimensional array corresponding to R, G and B of each pixel. In the direction perpendicular to the above-mentioned one side of the waveguide substrate 1, the minute lenses 6 are provided by the number of pixels in this direction.

A concrete example of the waveguide substrate 1 is shown in FIGS. The waveguide substrate 1 shown in FIG. 2 has a waveguide 1b made of glass in a striped pattern on one main surface of the substrate 1a at the same pitch as the arrangement pitch of the semiconductor lasers in the semiconductor laser array. Waveguide substrate 1 shown in FIG.
Is a waveguide in which the waveguides 1c made of striped glass are joined at the same pitch as the arrangement pitch of the semiconductor lasers in the semiconductor laser array via the substance 1d having a lower refractive index to form a flat plate as a whole. These waveguides 1b,
The refractive index of the glass constituting 1c is, for example, n = 1.585.
Is.

FIG. 4 shows details of this color display. As shown in FIG. 4, on the one main surface of the waveguide substrate 1, a waveguide made of glass in a stripe shape is formed on the waveguide substrate 1 so as to correspond to each semiconductor laser (the waveguide 1b shown in FIG. 2). Alternatively, the transparent electrode 7 having the same shape as the waveguide 1c) shown in FIG. 3 is provided. The transparent electrode 7 is made of ITO, for example. On one main surface of the waveguide substrate 1, for example, an optical switch 8 using FLC is provided in a stripe shape extending in a direction orthogonal to the transparent electrode 7, and the optical switch 8 is provided with a parallelogram cross-sectional shape. An oblique mirror 9 made of, for example, glass having a refractive index n = 1.585 is provided. Although not shown in FIG. 4, a transparent electrode made of, for example, ITO is provided on the lower surface of the oblique mirror 9 so that a voltage can be applied between the transparent electrode and the transparent electrode 7. There is. On the other hand, electrodes 2 a and 2 b are provided on a pair of sides of the light diffusion plate 2 parallel to the extending direction of the oblique mirror 9, and these electrodes 2 a and 2 b are provided.
A voltage can be applied between a and 2b.

An example of the detailed structure of the optical switch 8 using FLC is shown in FIG. As shown in FIG. 5, in this example, a waveguide made of striped glass of the waveguide substrate 1 (the waveguide 1b shown in FIG. 2 or the waveguide 1 shown in FIG. 3) is used.
c) A transparent electrode 7 made of, for example, ITO, a liquid crystal alignment film 10 made of polyimide, a FLC layer 11, a liquid crystal alignment film 12 made of polyimide, and ITO, for example.
The transparent electrode 13 made of is sequentially laminated, and the optical switch 8 is configured by these. As an example of the thickness of each part, the transparent electrodes 7 and 13 are 0.50 μm, and the liquid crystal alignment film 1 is
0 and 12 are 0.142 μm, FLC layer 11 is 1.5 μm
Is. This optical switch 8 is capable of high-speed switching on the order of microseconds. When the optical switch 8 is off, that is, when no voltage is applied between the transparent electrodes 7 and 13, the refractive index of the FLC layer 11 is 1.43, for example.
On the other hand, when the optical switch 8 is on, that is, when a voltage is applied between the transparent electrodes 7 and 13, FL
The refractive index of the C layer 11 is, for example, 1.585, which is the same as that of the striped glass of the waveguide substrate 1.

Next, a method of operating the color display constructed as described above will be described. As shown in FIGS. 1 to 5, first, driving of each semiconductor laser of the semiconductor laser array is controlled by an electric signal according to an image to be displayed,
It controls which pixel emits what color. As a result,
Laser light 14 is emitted from one or more of the semiconductor lasers 3, 4, 5 (FIG. 4), and the laser light 14 is emitted from the striped glass of the waveguide substrate 1 via a condenser lens (not shown). It is incident on the end face of the waveguide (waveguide 1b shown in FIG. 2 or waveguide 1c shown in FIG. 3) and is guided while being repeatedly reflected in the waveguide. At this time, the optical switch 8 determined by the electric signal corresponding to the image to be displayed is turned on, whereby the FLC of the optical switch 8 is turned on.
As a result of the layer 11 having the same refractive index as that of the waveguide made of striped glass of the waveguide substrate 1, the laser light 14 is extracted to the outside of the waveguide substrate 1 through the optical switch 8 and is reflected by the oblique mirror 9. Incident. The laser light 14 that has entered the oblique mirror 9 is reflected by the end surface of the oblique mirror 9 that is inclined with respect to the waveguide substrate 1, and is emitted in a direction perpendicular to one main surface of the waveguide substrate 1 ( (Fig. 4). At this time, for example, the opacity is controlled by the voltage applied between the electrodes 2a and 2b so that one of the plurality of light diffusion plates 2 is opaque and the other is transparent. FIG. 4 shows a case where the outermost light diffusion plate 2 as viewed from the waveguide substrate 1 is opaque and the remaining two light diffusion plates 2 are transparent. In this case, the laser light 14 passes through the two transparent light diffusing plates 2 and reaches the outermost opaque light diffusing plate 2 and is projected to form a projected image 15. Here, since the laser light 14 has a high directivity, the light can be projected only on the selected specific light diffusion plate 2 without spreading the light in the process of passing through the light diffusion plate 2. What is important here is that the opacity of each light diffusing plate 2 can be controlled by the voltage applied between the electrodes 2a and 2b, so it is possible to freely decide which light diffusing plate 2 the projected image 15 is formed on. Is to be done. This means that the projection position can be changed in the depth direction.

Furthermore, it is also possible to project onto two or more light diffusion plates 2 at the same time. FIG. 6 shows, as an example, a case where two light diffusion plates 2 are simultaneously projected. As shown in FIG. 6, by making the two light diffusion plates 2 opaque, it is possible to simultaneously create two identical images. In this case, as shown in FIG. 7, an observer feels that an image (here, an example of the letter “F” is shown) is present between the two light diffusion plates 2. Furthermore, 2
The brightness of the image formed on each light diffusion plate 2 can be controlled by making the opacity of the light diffusion plates 2 different. In FIG. 7, as an example, the opacity of the light diffusion plate 2 on the waveguide substrate 1 side is small, and
The case where the opacity of is large is shown. In the case of the example shown in FIG.
For the observer, the image on the front side is brighter than the image on the back side, so that the image felt by the observer seems to be on the front side even between the two light diffusion plates 2. Become. In this way, an image perceived by the observer appears between the two light diffusion plates 2 based on the brightness ratio of the image (see Japanese Patent No. 3022558).

Here, the reason why the brightness of the image formed on each light diffusion plate 2 can be controlled by making the opacity of the two light diffusion plates 2 different as described above will be described. Now, let P _{0 be} the intensity of the light emitted from the waveguide substrate 1 side.
Is the ratio of the light scattered by the i-th light diffusing plate 2 to k
_i (0 ≦ k _i ≦ 1), the i-th light diffusing plate 2
The brightness P _{i at} is expressed by the following equation.

P ₁ = P ₀ k ₁ P ₂ = P ₀ (1-k ₁ ) k ₂ P ₃ = P ₀ (1-k ₁ ) (1-k ₂ ) k ₃ ... P _i = P ₀ (1-k ₁ ) (1-k ₂ ) ... (1-k _i-1 ) k _i

The brightness can be adjusted by controlling the opacity of each light diffusing plate 2, that is, the ratio of light scattering, based on this equation.

In the first embodiment, since the minute lens 6 is arranged in front of each pixel, the image forming position can be largely changed by the minute lens 6 as shown in FIG. That is, the focal length of the minute lens 6 is f
Then, the distance s from the projection position to this minute lens 6
On the other hand, the image formation point is 1 / f = 1 measured from the minute lens 6.
It is located at the distance x obtained from the imaging formula of / s + 1 / x, and it is understood that the imaging position can be largely changed by the projection position according to this imaging formula. Here, when the distance s from the projection position to the minute lens 6 is larger than the focal length f, that is, when f <s, the image is formed forward (real image), and when f> s, the image is formed rearward. (virtual image). FIG. 9 shows the result of calculation by changing the image forming position f when f <s. From FIG. 9, the light diffusion plate 2
It can be seen that by changing the projection position (light emitting point) on the side by several millimeters, the image forming position can be greatly changed to several tens of centimeters. According to this method, the image forming position can be changed sufficiently large even with the fixed type microlens 6, and a large parallax and a sense of depth can be obtained. For example, when the focal length of the microlens 6 is f = 5 mm, the lens array of the microlens 6 makes it possible to obtain parallax on the order of several tens of centimeters.

As described above, according to the first embodiment, a plurality of light diffusing plates 2 whose opacity can be controlled by a voltage are provided in parallel with the waveguide substrate 1 so as to respond to an image to be displayed. By irradiating the light diffusing plates 2 with the laser light 14 vertically emitted from the waveguide substrate 1, a projected image 15 is formed on the selected one or a plurality of light diffusing plates 2. The projection position can be changed in the depth direction when viewed from the observation position. For this reason, it is possible to obtain a large parallax and a sense of depth, and when viewing a stereoscopic image, it is not necessary to use special glasses, and nearby objects are close, and distant objects are distant. As you can see by changing the focus of your eyes, you can get a natural 3D image. Therefore, there is little discomfort and there is little eye fatigue even when viewed for a long time. Further, since the display does not become thick unlike the method of Japanese Patent No. 3022558, which obtains a stereoscopic effect by combining two screens, a thin stereoscopic display can be obtained.

Next, a second embodiment of the present invention will be described. In the second embodiment, an active matrix driving type color display will be described. The overall structure of this color display is shown in FIG.

As shown in FIG. 10, in this color display, two light diffusion plates 2 are provided.
A transparent electrode 16 made of, for example, ITO is provided on the entire lower surface of each of the light diffusion plates 2, and an upper surface thereof is provided.
A transparent pixel electrode 17 made of, for example, ITO is provided for each R, G, and B section of one pixel. R of each pixel,
TF as a pixel switching element is provided in each of the G and B sections.
A T (thin film transistor) 18 is provided. The pixel electrode 17 is connected to the drain of this TFT 18.
Further, a gate line 19 parallel to the transparent electrode 7 of the waveguide substrate 1 and a source line 20 orthogonal to the gate line 19 are provided on each upper surface of the light diffusion plate 2. Both the gate line 19 and the source line 20 are made of, for example, ITO. Here, the gate line 19 is connected to the gate of the TFT 18 arranged in that direction, and the source line 20 is connected to the source of the TFT 18 arranged in that direction. The above is the same as in a normal active matrix drive type liquid crystal display. In this case, unlike the first embodiment,
The electrodes 2a and 2b on both ends of the light diffusion plate 2 are not provided. Other configurations are similar to those of the first embodiment. Note that, in FIG. 10, the semiconductor lasers 3, 4, 5 and the minute lens 6 which are actually provided are not shown.

In this color display, the pixel electrode 17 is driven by the TFT 18 selected according to the image to be displayed, so that each pixel, further R,
A voltage can be applied to the light diffusion plate 2 for each of the G and B sections, and thus the opacity of the light diffusion plate 2 can be controlled for each pixel or for each section. Figure 10
In the figure, as an example, it is shown that the brightness of the projected image 15 becomes strong, medium, and weak depending on the opacity of the light diffusion plates 2 of three pixels adjacent to each other.

According to the second embodiment, the same advantages as those of the first embodiment can be obtained, and the opacity of the light diffusion plate 2 can be controlled for each pixel, so that each pixel can be controlled. It is possible to control the sense of depth for each. Therefore, the sense of depth that the observer can feel can be made different for each pixel, and the sense of depth of the stereoscopic image can be more faithfully reproduced. When a PDLC is used for the light diffusion plate 2, the response speed of this PDLC is on the order of a few milliseconds, so
It is possible to sufficiently deal with the scanning time of 1/60 seconds per screen.

Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-mentioned embodiments, and various modifications can be made based on the technical idea of the present invention.

For example, the numerical values, structures, shapes, materials and the like mentioned in the above embodiments are merely examples, and different numerical values, structures, shapes, materials, etc. may be used if necessary.

Specifically, in the above-described first embodiment, the three laser beams 1 from the semiconductor lasers 3, 4, and 5 are used.
4 are incident on the end faces of the separate striped waveguides of the waveguide substrate 1, the three laser beams 14 from these semiconductor lasers 3, 4, 5 are of the same striped waveguide. You may comprise so that it may inject into an end surface.
In this case, one microlens 6 should be provided for each pixel.

[0032]

As described above, according to the present invention, the projection position of an image is changed in the depth direction by irradiating a plurality of projection plates with light having directivity according to the image to be displayed. be able to. Therefore, the gap between the focal position of the eye and the image can be eliminated, and the fatigue and discomfort of the eye can be significantly reduced, and the display device can be thinned.

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic configuration of a color display according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a structural example of a waveguide in the color display according to the first embodiment of the present invention.

FIG. 3 is a perspective view showing a structural example of a waveguide in the color display according to the first embodiment of the present invention.

FIG. 4 is a perspective view showing details of the structure of the color display according to the first embodiment of the present invention.

FIG. 5 is a cross-sectional view showing details of the structure of the optical switch section in the color display according to the first embodiment of the present invention.

FIG. 6 is a perspective view for explaining the operation of the color display according to the first embodiment of the present invention.

FIG. 7 is a schematic diagram for explaining the operation of the color display according to the first embodiment of the present invention.

FIG. 8 is a schematic diagram for explaining the operation of the color display according to the first embodiment of the present invention.

FIG. 9 is a schematic diagram for explaining the operation of the color display according to the first embodiment of the present invention.

FIG. 10 is a perspective view showing a schematic configuration of a color display according to a second embodiment of the present invention.

[Explanation of symbols]

1 ... Waveguide substrate, 1b, 1c ... Waveguide, 2 ...
・ Light diffusing plate 3, 4, 5 ... Semiconductor laser, 6 ...
Microlenses, 7, 13, 16 ... Transparent electrodes, 8 ...
Optical switch, 9 ... Diagonal mirror, 14 ... Laser light, 15 ... Projected image, 17 ... Pixel electrode

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hikaru Ishimoto             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation F term (reference) 2H088 EA20 EA33 GA04 GA08 MA02                       MA04 MA05 MA06 MA13 MA16                 5C061 AA06 AA16 AA25 AB14 AB17

Claims (18)

[Claims] 1. A display device, which is configured so that a position at which a displayed image is projected can be changed in the depth direction when viewed from an observation position. 2. A display comprising a plurality of projection plates, wherein the images are displayed by irradiating the plurality of projection plates with light having directivity according to the images to be displayed. apparatus. 3. The display device according to claim 2, wherein the light is emitted from the back side of the plurality of projection plates when viewed from the observation position. 4. The display device according to claim 2, wherein the plurality of projection plates are provided in parallel with each other. 5. The display device according to claim 2, wherein the opacity of the projection plate to the light is controllable. 6. The display device according to claim 2, wherein the projection plate is a light diffusion plate. 7. The display device according to claim 6, wherein the light diffusing plate can control opacity with respect to the light. 8. The display device according to claim 6, wherein the light diffusing plate can control the degree of scattering of the light. 9. The display device according to claim 6, wherein the light diffusing plate is made of liquid crystal. 10. The display device according to claim 6, wherein the light diffusion plate is made of a polymer-dispersed liquid crystal. 11. The display device according to claim 2, wherein the light having the directivity is a laser light. 12. The waveguide is characterized in that the light is introduced from one end face thereof, the light is taken out of the waveguide by an optical switch, and the plurality of projection plates are irradiated with the light. 2. The display device according to item 2. 13. The light is introduced into the waveguide from one end face thereof, the light is extracted to the outside of the waveguide by an optical switch, and the light is reflected in the direction perpendicular to the waveguide by using an oblique reflection plate to obtain a plurality of the light beams. The display device according to claim 2, wherein the projection plate is illuminated. 14. The display device according to claim 2, wherein the opacity of the projection plate for each pixel is controlled. 15. The display device according to claim 13, wherein the projection plate for each pixel is driven by active matrix. 16. The display device according to claim 2, further comprising a lens for forming an image projected on at least one projection plate of the plurality of projection plates. 17. The display device according to claim 16, wherein each pixel has the lens. 18. A display method characterized in that the image is displayed by irradiating a plurality of projection plates with light having directivity according to the image to be displayed.