JPH0155461B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a three-dimensional display device, and particularly to a display device that can provide a true stereoscopic image.

[Technical background of the invention and its problems]

In recent years, three-dimensional images,
That is, there is an increasing demand for a display device that can display a three-dimensional image with depth information in addition to two-dimensional information.

Three-dimensional display devices that have been put into practical use use, for example, two-color filters, red and blue, to take images from two points separated by a distance similar to the distance between human eyes, and project the images onto a screen with their positions shifted appropriately. However, by viewing these images through two color filters, red and blue, a pseudo-stereoscopic image can be obtained. This is just a pseudo three-dimensional image synthesized in the human brain, and true three-dimensional information is not provided. This is made clear by the fact that no new information is obtained even when viewed from a different angle.

Therefore, several attempts have been made to realize display devices that can display true stereoscopic images rather than pseudo-stereoscopic images. The first one is JP-A-1978-
This is shown in Publication No. 26153. This involves stacking a large number of liquid crystal display panels in which pixels are divided by sandwiching a liquid crystal layer between select electrodes arranged in the horizontal direction and select electrodes arranged in the vertical direction, and these display panels are sequentially selected. A three-dimensional image is displayed by repeating the scanning and driving operation according to three-dimensional image information.

According to this device, the number of select electrodes arranged in the vertical direction in one liquid crystal display panel is m, the number of panels is n, and the response time of the liquid crystal (the time required from the start of application of an electric field to the scattering state) Letting τ be, it takes m×n×τ time to drive all the panels. Assuming the same resolution as a TV image, if m = 512 and n = 16 images, τ
Since this is usually several msec, the time required for this one scanning drive is about 10 seconds.
In this case, the displayed image flickers extremely and cannot be viewed as a three-dimensional image, making it impractical.

Furthermore, this device requires forming a large number of select electrodes at fine pitches on the display panel, which also has the disadvantage of increasing manufacturing costs.

[Purpose of the invention]

An object of the present invention is to provide a three-dimensional display device that can provide high-quality true stereoscopic images without flickering.

[Summary of the invention]

This invention displays three-dimensional images by laminating a plurality of display panels that are normally transparent and change their optical state when an electric field is applied to emit visible light in response to an incident light beam such as a laser beam. constitutes the body,
An electric field is sequentially and selectively applied to each display panel, and the display panel whose optical state has changed due to the application of the electric field is modulated by three-dimensional image information.
In addition, a three-dimensional image, that is, a true three-dimensional image, is displayed by scanning the display panel with a light beam that is irradiated obliquely from a position off the center line in the stacking direction of the display panel. It is characterized by

In addition to liquid crystal, materials having various electro-optic effects can be used as the material for the display panel.

〔Effect of the invention〕

According to this invention, image formation on each display panel is performed in an extremely short time by beam scanning, similar to television scanning or the like. Therefore, the response time of the display panel to the application of an electric field, that is, the time from the start of application of the electric field until the optical state changes, is τ.
If the number of display panels is n, the time required to drive all the display panels is approximately n·τ, which is significantly shorter than the conventional method. Therefore, the image synthesized by the entire display body is rich in three-dimensional effect and becomes a high-quality three-dimensional image without flickering.

Further, by shortening the driving time, it is possible to increase the number of display panels and increase the amount of information in the depth direction.

Furthermore, in a display panel, it is sufficient to simply have an electrode for applying an electric field to select the entire panel.
Since there is no need for a large number of matrix-like select electrodes as in the prior art, the structure is simple and manufacturing is easy, reducing manufacturing costs. In addition, by irradiating the display panel with a light beam obliquely from a position away from the center line of the display panel in the stacking direction,
When viewing the display from the side opposite to the light beam irradiation side,
The straight light beam does not enter the eye through the display panel, making it possible to display high-quality three-dimensional images.

[Embodiments of the invention]

FIG. 1 shows an outline of a three-dimensional display device according to an embodiment of the present invention.

In the figure, a three-dimensional image display body 1 is constructed by laminating flat display panels 2 ₁ to 2n in this example. Specific examples of the display panels 2 ₁ to 2n will be explained later, but they are normally transparent, and when an electric field is applied by the panel selector 3, their optical state changes, for example, to become opaque, and when the light beam 4 is incident, the display panels 2 1 to 2n are transparent. It scatters or emits visible light. The panel selector 3 sequentially and selectively applies a predetermined electric field to each of the display panels 2 ₁ to 2n, and in the illustrated example, it is assumed that the electric field is applied to the display panel 2 ₂ shown by hatching.

In this state, a light beam 4 modulated (for example, turned on or off) according to three-dimensional image information, emitted from a scanning means (not shown), such as a laser beam, is used to move the display panel ₂₂ to which an electric field is applied from the panel selector 3 to the television. Scanning is performed in the X and Y directions in the same way as scanning. At this time, on the display panel 2 ₂ ,
Visible light is selectively scattered only in the area irradiated with the beam 4, and this can be recognized with the naked eye. This results in
One image out of n two-dimensional images constituting the three-dimensional image will be displayed on the display panel ₂₂ .

Thereafter, in the same manner, each of the display panels 2 ₁ to 2n is sequentially selected by the panel selector 3, and the selected display panel, that is, the display panel to which an electric field is applied, is scanned by the light beam 4. By repeating the process at a period of time (approximately 1/30 seconds) or less, it is possible to display a three-dimensional image, that is, a true stereoscopic image, on the display body 1 .

Note that the light beam 4 needs to be modulated by the three-dimensional image information to be displayed as described above;
Such three-dimensional image information can be obtained, for example, by capturing images of a subject from various angles using multiple television cameras, etc., and then synthesizing the resulting image signals as three-dimensional image information through image processing using a computer. Obtainable. Of course, the three-dimensional image information is not based on the imaging output, but may be synthesized from the beginning using software.

The three-dimensional image displayed on the display 1 can be viewed from either the incident side of the light beam 4 (display panel 2 ₁ side) or the opposite side (display panel 2n side), but in reality, the light beam There is a scanning means, etc. on the irradiation side of 4, and since these become an obstruction, it is preferable to configure it so that it can be viewed from the opposite side. In that case, it is important to prevent the light beam 4 that has passed through the display panels 2 ₁ to 2n and gone straight from entering the eyes. Therefore, in the present invention, as shown in FIG. 1, the light beam 4 is irradiated obliquely from a position away from the center line in the stacking direction of the display panels 2 ₁ to 2n.

In this way, even when the display body 1 is viewed from the side opposite to the scanning means, the light beams 4 that have traveled straight through the display panels 2 ₁ to 2n will not enter the eyes, and the light beams 4 that have traveled straight through the display panels 2 1 to 2n will not be scattered by the display panels 2 ₁ to 2n. Only secondary luminescence such as is observed. Therefore, there is an advantage that a three-dimensional image that is very easy to see can be obtained.

Next, the display panels 2 ₁ to 2n will be specifically explained. Display panel materials include liquid crystal, which scatters visible light in response to incident light beams when an electric field is applied, and materials that have an electro-optic effect in a narrow sense (liquid crystal is also an electro-optic effect material in a very broad sense). ), that is, there are materials that have the Pockels effect (first-order electro-optic effect) or the Liichi effect (second-order electro-optic effect). Specific examples of these electro-optic effect materials include PLZT (Plomb
lanthanum Zilconate titanate), KDP
(KH ₂ PO ₄ ), ADP (HH ₄ H ₂ PO ₄ ), KDA
(KH ₂ AsO ₄ ), RDP (RbH ₂ PO ₄ ), ADA
(NH ₄ H ₂ AsO ₄ ) and the like. In particular, PLZT is the most effective in terms of responsiveness, etc.

FIG. 2 shows some specific configuration examples of the display panels 2 ₁ to 2n, in which a is an example using a liquid crystal, and b and c are examples using an electro-optic effect material, respectively.

In FIG. 2a, a liquid crystal 13 is sealed between transparent substrates 11 made of transparent glass, etc., and a liquid crystal 13 is placed between transparent electrodes 12 made of a transparent conductive material film such as Nesa film or ITO film deposited on the transparent substrate 11. , an electric field is applied from the panel selector 3. Note that an electrode for applying an electric field may be arranged around the layer of liquid crystal 13.

Figures 2b and 2c show examples in which a large number of electro-optic effect material layers 14 are laminated. An electrode 16 for applying an electric field (this electrode does not necessarily have to be transparent) is provided.

Here, the response time τ of each of the display panels 2 ₁ to 2n is several m sec in the case of a liquid crystal, and even shorter in the case of an electro-optic effect material, so the time required to drive the entire display 1 once is n·τ (n is display panel 2 ₁
~2n images), even if n = 16 images, it is easy to make the afterimage time for the human eye less than 1/30 seconds, and n
It is also possible to obtain a three-dimensional image with a richer three-dimensional effect by increasing the number of images.

This invention can be implemented with various modifications. For example, as a three- _dimensional image display body 1 , as shown in FIG.
~2n may be laminated concentrically to form a hemispherical structure as a whole. In this case, the irradiation position of the electromagnetic wave beam 4 is not the (x, y) coordinate but the position of the display panels 2 ₁ to 2n Pi (i=1, 2, . . .
n), and the angles of the two orthogonal directions of the beam 4 are given as θ, the angular coordinates (Pi, θ) are given.

Further, as the three-dimensional image display body, it is also possible to use a structure in which semi-cylindrical display panels having different diameters are arranged coaxially.

Furthermore, the light beam is not limited to the laser beam, and various selections can be made depending on the constituent material of the display panel.

Furthermore, although the above embodiments have been described in terms of monochrome display, color display is also possible. For example, when using a liquid crystal, color display can be performed by using multicolor laser beams such as red, blue, and green, or by irradiating multispectral beams using a multicolor guest-host liquid crystal. When using an electro-optic effect material, color display is possible by incorporating a color filter into the three-dimensional image display.

Note that a three-dimensional image display body can also be constructed by laminating display panels made of a material that itself emits visible light upon incidence of a light beam.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a three-dimensional display device according to an embodiment of the present invention, FIGS. 2 a to c are sectional views showing various configuration examples of display panels used in the present invention, and FIG. FIG. 3 is a schematic configuration diagram of a three-dimensional image display body according to another example. 1 ... three-dimensional image display body, 2 ₁ to 2n... display panel, 3... panel selector (electric field applying means),
4...Light beam.

Claims (1)

[Claims] 1. A three-dimensional image display body consisting of a stack of display panels that are normally transparent and whose optical state changes when an electric field is applied to emit visible light in response to an incident light beam, and each display panel of this display body. means for sequentially and selectively applying an electric field; and a display panel to which the electric field is applied by the means, modulated by three-dimensional image information and from a position away from the center line in the stacking direction of the display panel with respect to the display panel. 1. A three-dimensional display device comprising: means for scanning with a light beam emitted obliquely.