JPH0321924A - Large screen display device - Google Patents

Abstract

PURPOSE:To make displaying with a bright screen with high accuracy by reading out the images written into space light modulation elements by laser beams with a high-luminance light source and projecting the images onto the screen. CONSTITUTION:Image input optical systems 1R, 1G, 1B modulate the laser beams respectively according to red, green and blue picture signals and two- dimensionally scan the modulated laser beams. The space light modulation elements 2R, 2G, 2B are formed by using ferroelectric liquid crystals and the respective writing faces thereof are disposed to face the red, green and blue image input optical systems 1R, 1G, 1B. The input images are once written into the space light modulation elements by the scanning of the laser beams in such a manner and the written images are read out of the space optical modulating elements by the light from the high-luminance light source. These images are macroprojected on the screen 7, etc., and are thereby formed thereon. The writing to the space light modulation elements by the scanning of the laser beams allows the writing with the high accuracy and allows the displaying of the images with the high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a large screen display device that displays images on a large screen.

[Prior Art] Conventionally, regarding this type of large screen display device, as shown in the conventional example in FIG. 6, a projection type CRT method is used in which light emitted from a CRT screen is magnified by a lens system and projected onto the screen. is well known. In the conventional example shown in FIG. 6, 10l is a CRT, 102 is a lens system, 103f is an i-screen, ! 04 is a mirror. CRT l 0 1
is a high-brightness type, and the light emitted from the screen is magnified by a lens system 102, folded by a mirror 104, and projected onto a screen 103. In this projection type CRT system, in the case of full color, in order to compensate for the lack of brightness, red color is used as shown in another conventional example in FIG. green, blue 3
Three CRTs compatible with primary colors: 10IR, IOIG,
Using IOIB, these images are also projected onto the screen 103 so as to coincide with each other.

[Problem to be Solved by the Invention] However, in the projection CRT type large screen display device in the conventional technology described above, in any case, there is a limit to the brightness of the CRT, so the brightness of the display screen on the screen 103 is limited. An unavoidable problem was the lack of. This poses a problem in that it is difficult to see when the room is bright.

In addition, such large-screen projection CRT display devices inevitably use high-brightness CRTs, but it is difficult to increase the number of pixels sufficiently on such high-brightness CRTs. Therefore, there were problems such as not being able to obtain high-definition images.

The present invention was devised to solve the above-mentioned problems, and aims to provide a large screen display device that can make the display screen brighter and have higher definition. .

[Means for Solving the Problems] A large screen display device of the present invention for achieving the above object includes: a spatial light modulator using a ferroelectric liquid crystal; a means for modulating laser light according to an image signal; an image input optical system having means for two-dimensionally scanning the modulated laser light onto a writing surface of the spatial light modulator; A control unit for controlling a series of input images, a high-intensity light source, and an optical system for reading and enlarging and projecting the image written on the spatial light modulation element using light from the light source. Features.

[Function] The present invention does not directly project the CRT luminescent image onto a screen as in the past, but instead writes the input image on the spatial light variable R element by scanning a laser beam, and then uses light from a high-intensity light source to write the input image onto the spatial light variable R element. The written image is read out from the spatial light modulation element and is enlarged and projected onto a screen or the like to form an image. In the above, writing on the spatial light modulation element by scanning a laser beam enables high-definition writing and enables high-definition image display. The use of a spatial light modulation element also enables image readout with high-intensity readout light, brightening the projected image.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram showing the basic structure of an embodiment of the present invention. In this embodiment, a case of full color is taken as an example. IR
, IG, and IB are each red. It is an image input optical system that modulates laser light according to green and blue image signals and scans the modulated laser light (laser beam) two-dimensionally.
2R, 2G, and 2B use ferroelectric liquid crystal, and each writing surface is colored red. Green, blue image input optical system IR, IC, IB
3R, 3G, 3B are lead electrodes of each SLM 2R, 2G, 2B, and 4 supplies laser light to the image input optical system IR, IG, IB. This is the laser light generating section that generates the laser beam. The image input optical systems IR, IC, and IB each have a scanning surface of SL.
Place it so that the writing side of M2R, 2G, and 2B is on the red side. green. An image by a laser beam corresponding to a blue image signal is irradiated onto each of the writing surfaces of the SLMs 2R, 2G, and 2B and input. 5 are three primary color image signals R, , G.5 based on the video signal VS. ,B. and vertical scanning drive signal Rt
, Gt. B* and horizontal scanning drive signals R, G3+
B, to the corresponding image input optical systems IR, IG, 1B to control the irradiation of the image by the laser beam, and a drive pulse signal R4.B synchronized therewith. G. ,B. is applied to each of the lead electrodes 3R, 3G, and 3B to control writing of the image irradiated onto the writing surface onto the SLMs 2R, 2G, and 2B;
B+. : High brightness light source for reading written images, 7 is the screen, 8 is the light from light source 6 SLM2R, 2G
, 2B is a projection optical system for reading out written images and projecting them onto the screen 7 in an enlarged manner.

The configurations of the image input optical systems IR, IG, and IB mentioned above will be explained below. Laser light is manually applied to each image input optical system IR, IC, and IB from a laser light generating section 4. In the optical path of this laser light, there are red and green lights, respectively. Blue image signal R
+, G +, B + modulators 11R, ItG, and IIB that perform intensity modulation of laser beams according to
．． Gt. Movable mirrors +2R, 12G, and 12B that scan in the vertical direction by By are arranged. Each optical path of the laser beam scanned by the movable mirrors 12R, 12G, and 12B includes movable mirrors 13R, 13G, and 13B that scan the laser beam in the horizontal direction using drive signals R s, G s, and B s for horizontal scanning, respectively. Place.

As these movable mirrors 12R-13B, for example, a galvano mirror or a borigon mirror is used. Movable mirror! 2R
．． 12G. Each set of 12B, 13R, 13 (1; 13B) is arranged so that the scanning plane of the laser beam two-dimensionally scanned by each set becomes the writing surface of each SLM 2R, 2G, 2B. Movable mirror 13R .13G,1
Lens systems 14R, 14G, and 14B are interposed between 3B and Sl, M2R, 2G, and 2B to focus the respective laser beams into dots on each writing surface.

Next, the laser light generating section 6 uses the laser light source 4l, half mirrors 42, 43, and reflection mirrors 44, 45 to transmit the laser light from one laser light source 4l to each image input optical system IR, IG. Arrange to distribute to IB. first,
For the image input optical system trt, half mirrors 42 and 43 are arranged so as to guide the laser beam by reflection from the half mirror 42 and reflection from the half mirror 43. Next, a reflecting mirror 44 is arranged to guide the laser beam that has passed through the half mirror 42 to the image input optical system tC by reflection from the reflecting mirror 44, and a half mirror 43 is arranged to the image input optical system IB. The reflecting mirror 45 is arranged so that the transmitted laser beam is guided by reflection from the reflecting mirror 45.

Next, the configuration of the projection optical system 8 will be explained. In front of the light source 6, there is a slit 81 and an SLM2R, which uniformly distributes the light from the light source 6.
A lens 82 for making the light incident on 2G and 2B, and a lens 8
Cold filter 83 that cuts heat rays from light from 2
and place it. The optical path according to this configuration is arranged so as to face the readout side of the SLM 2G. On this optical path, there is a polarizing beam splitter prism (PBS) 84 with one reflection direction facing the writing surface of SLM2B, and a polarization beam splitter prism (PBS) 84 with one reflection direction facing the SLM2R, transmitting green light to SLM2G and red light to SLM2R. Guicroic mirror that reflects
85. Filters 86R, 86G, and 86B that transmit only red, green, and blue light are arranged on the readout surface side of each SLM 2I'{, 2G, and 2B, respectively, and filters 86R, 86G, and 86B that transmit only red, green, and blue light are arranged on the readout surface side of each SLM 2I'{, 2G, and 2B, and filters 86R, 86G, and 86B that transmit only red, green, and blue light are arranged on the other side of the polarization beam splitter prism 84 in the reflection direction. By the reflected readout light from each SLM 2R, 2G, and 2B combined via the beam splitter prism 84,
A lens 87 for enlarging and projecting a written image onto the screen 7 is provided.

Next, the configuration of the spatial light modulator (SLM), which is the main component of this embodiment, will be explained.

Figure 2 shows the ferroelectric liquid crystal (hereinafter FLC) in the above embodiment.
2 is a block diagram of a spatial light modulator using a spatial light modulator (disclosed by the applicant in Japanese Patent Application No. 1-45716).
is a spatial light modulator wood body (SLM), 3 is a lead electrode, 1
5 is a holder for holding the SLM, and 84' is a polarizing beam splitter prism (hereinafter abbreviated as PBS). The two-dimensional pattern (image formed by laser beam scanning) that becomes the modulation signal is irradiated on the old side of the SLM2 as the old side light Lw, but at the same time, a drive pulse signal is applied to the SLM2 to It will be done. This drive pulse signal is applied from the control section 5 in FIG. 1 in synchronization with the video signal VS (n4+B4.G4). PBS8
Here, 4' has the function of transmitting linearly polarized light (p-polarized light) parallel to the reflecting surface and reflecting linearly polarized light (s-polarized light) orthogonal thereto. The readout light (light from the readout light source 6 in Figure 1) LR passes through the PBS 84' and becomes a spatially uniform linearly polarized beam, enters the readout surface side of the SLM 2, is modulated and reflected, and then becomes a polarized beam. Only the light whose surface has been rotated is transmitted through the PBS 84' and read out as an intense pattern. In this way, the SLM 2 has the function of writing a two-dimensional pattern such as an image using the writing light L1, and reading out the written two-dimensional pattern using another light (reading light) LR. This allows S
LM2 is amplification of image light. Processing such as inversion or wavelength conversion between read light and write light can be performed.

FIGS. 3(a) and 3(b) are diagrams showing a more detailed structure of the spatial light modulator (SLM), where (a) is a side view and (b) is a side view.
) is a top view showing the electrode pattern, and FIG.
a) and (b) are orientation state diagrams of ferroelectric night crystals (FLC). 2l is a glass substrate on the writing side, and 21 is a glass substrate on the reading side. A dielectric electrode 26 to which one lead electrode 3 for applying a driving pulse signal is connected, a photoconductive layer 22 sensitive to writing light, a dielectric mirror 23, and an alignment film 25 are laminated on the glass substrate 2l. A transparent electrode 26' and an alignment film 25' are laminated on the glass substrate 21'. The glass substrates 2l and 21' configured in this way are placed on a substrate 2 such that the alignment films 25 and 25' face each other.
Placed via 7. A gap of constant thickness created by the spacer 27 is filled with FLC 24, and sealed and fixed with a sealant 28.

The transparent electrode 26' of the glass substrate 21' is connected to the glass substrate 2l.
A silver paste layer 29 is used to electrically connect to a transparent electrode 26'' which connects the other lead electrode 3' for applying a driving pulse signal formed on the side.Alignment films 25, 25 on each glass substrate 2l. ' as shown in Figure 4, both the upper and lower glass substrates 21.
′ is also lightly aligned. At this time, depending on the direction of the electric field, the molecule 24a of the FLC 24 is in the same direction as the polarization axis P of the incident light for writing (up state (a)), or in a direction 45 degrees to it (down state (b)). Orient it in alignment. In the up state, the readout light that is incident on the layer of the FLC 24 and reflected returns in its original polarization state.

On the other hand, in the down state, due to the refractive index anisotropy of the FLC 24, the polarization plane of the returning readout light is rotated.

At this time, the thickness d of F L C 2 4' is d=m・λ/
(4・Δn) (m=1.3,5,... λ: wavelength of readout light, Δ
n: refractive index difference in the long and short directions of the FLC molecule), the polarization of the returning light will be rotated by 90 degrees.

In this example, red as described above. The thickness d of each SLM 2 is set corresponding to the wavelengths of green and blue. Photoconductive layer 2
As 2, a photosensitive film such as amorphous silicon (a-Si) is used. The dielectric mirror 23 has a structure in which two types of dielectric films are alternately laminated. Further, in order to completely block the readout light from reaching the photoconductive layer 22, a thin light-shielding film made of an insulator may be provided between the photoconductive layer 22 of the aS (layer) and the dielectric mirror 23. As a material for this light-shielding film, for example, a polydiacetylene film or a transition metal oxide with a thickness of approximately 1 μm is suitable.Alternatively, as another structure of the light-shielding film, a film on or below the dielectric mirror 23 is suitable. Alternatively, instead of the dielectric mirror 23, a metal layer having a mesh-like insulated island-like arrangement pattern may be provided.

The operation and effect of the embodiment configured as above will be described. The following description will be given with reference to FIGS. 1 to 3.

FIG. 5 is a waveform diagram for explaining the operation of the optical space varying element (SLM) of this embodiment. S through PB9 84
The output characteristics of the readout light incident on LM2 (2R.2G, 2B) are such that in the up state of F'LC2 + (corresponding to the state where negative voltage is applied), the readout output light becomes dark (dark).
), it becomes bright in the down state (corresponding to the positive voltage application state). FIG. 5 shows the flow from the control unit 5 to the SLM.
2 shows the operating waveforms of the drive pulse signal applied to the drive pulse signal and the output light intensity of the readout light. Positive voltage +■ as shown in Figure 5
A drive pulse signal that swings to negative voltage -■ is sent from the drive power supply to S
At the same time, an erase light pulse is applied to the writing surface side of S LM 2 in synchronization with the -V side of the drive pulse signal using an unillustrated LED (light emitting diode) or the like. After the laser beams from the image input optical systems IR and ICIB are irradiated with the erasing light pulse, the images are similarly irradiated onto the writing surface side of the SLM 2 as writing light from the first pixel to the final pixel. When the laser beam is irradiated, the resistance of the photoconductive layer 22 shown in FIG. 3 decreases depending on the intensity of the writing light, so the voltage applied to the PLC 24 increases. First, by applying a negative voltage -■ in synchronization with the erasing light pulse, the FLC24 enters the up state, and the SLM
2 reads are reset to dark state. next,
When a positive voltage +V is applied, an electric field is applied to the PLO 24 according to the writing light intensity of the laser beam at that time, so that a readout light intensity proportional to the image signal is obtained.

Note that another SLM driving form that does not use an erase light pulse is also possible. In this case, instead of using an erasing light pulse, the absolute value of the negative voltage applied to the SLM 2 for erasing in the drive pulse signal is made larger than the positive voltage applied during writing. That is, if the electric field applied to the FLC 24 corresponding to the negative applied voltage is made sufficiently large, the state of the SLM 2 can be reset even without erasing light, and the SLM operation similar to that in the case of erasing light becomes possible.

In the configuration shown in FIG. 1, the input video signal
The image signals of the three primary colors R+, G+,
B + is input to each of the variables 11R, IIG, and IIB. In addition, in synchronization with these, the drive signal R of each movable mirror is
t+ G 1, B = and rt. , G3, B. are movable mirrors 12R, 12G, 12B, 13It, respectively.
13G and 13B, and the laser beam for each color signal is scanned at high speed in the vertical and horizontal directions.

Drive pulse signals (R., G4, B.) for each SLM 2 are also input from the control section 5 to each SLM 2. With these configurations, image signals corresponding to the three primary colors are written on the writing surface of each SLM 2 by two-dimensional scanning of the laser beam. On the other hand, in the readout light from the light source 6, the near-infrared light component that becomes a heat ray is cut by the cold filter 8l and enters the PBS 84, and only the S-polarized light component is reflected and passes through the filter 86B and enters the SLM 2B. At this time, the p-polarized light component passes through the PBS 84, and the red light is reflected by the guichroic mirror 85 and enters the 7S L M2R. Further, the green light component passes through the guichroic mirror 85 and enters the SLM 2G.

The red and green lights incident on each SLM2. The blue light is modulated by the image signals of the three primary colors and reflected, combined by the PBS 84, and then projected onto the screen 7 by the lens 87. At this time, the readout light incident on SLM2B is converted from S-polarized light to p-polarized light depending on the brightness of the written image, and the readout light incident on SLM2R and SLM2G is converted depending on the brightness of the written image. Since the p-polarized light is converted into the s-polarized light, the readout light is modulated in accordance with the input images of each of the three primary colors.

In the above, since a high-intensity halogen lamp or the like can be used as the light source 6 of the readout light, the screen 7
The image projected onto it will be extremely bright. Also,
Since the response speed of the SLM 2 is sufficiently fast at about 100 μs or less, the screen can be rewritten at high speed, and since writing can be performed with high definition, high definition projection display can be performed.

In addition, in the above example, the explanation is given in the case of full color, but if monochrome is fine, use a combination of image human power system, SLM, etc.! As a first step, it would be better to create a simpler system. In this way, the present invention can be applied in various ways according to its gist,
Various embodiments are possible.

[Effects of the Invention] As is clear from the above description, according to the large screen display device of the present invention, an image written on the spatial light modulation element with a laser beam can be written on the spatial light modulation element using a high-intensity light source. Since the image is read out and projected onto a screen, a bright, high-definition screen can be displayed. Furthermore, the present invention has the advantage of being compatible with various video signals such as television broadcasts, video tapes, and television cameras, and can be used in brighter locations than before, so it can be used in office automation equipment and entertainment. The range for flI can be further expanded as a display in advertisements and the like.

[Brief explanation of drawings]

Figure 1 is a basic configuration diagram showing one embodiment of the present invention, Figure 2 is a basic configuration diagram showing an embodiment of the present invention.
The figure is a block diagram of the spatial light modulation element of this example, and Fig. 3(a)
, (b) are detailed structural diagrams of the spatial light modulator, FIGS. 4(a) and (b) are orientation state diagrams of the ferroelectric branch crystals of the spatial light modulator, and FIG. 5 is a diagram of the present embodiment. FIG. 6 is a block diagram of one conventional example, and FIG. 7 is a block diagram of another conventional example. IR, IG, IB... image input optical system, 2R. 2G,
2B, 2... Spatial light modulation element (SLM), 4... Laser light generation section, 5... Control section, 6... Light source, 7.
...Screen, 8...Projection optical system, IIR, IIG
, 11B...Modulator, l 2R, 1 2G, 1 2B
... Movable mirror 13F{, 13G, 13B... Movable mirror 84... Deflection beam splitter prism (P
BS), 85... Guicroic mirror 86R, 86
G, 86B...filter, 87...lens.

Claims (1)

[Scope of Claims] A spatial light modulation element using ferroelectric liquid crystal, means for modulating laser light according to an image signal, and two-dimensional scanning of the modulated laser light on a writing surface of the spatial light modulation element. a control unit that controls modulation and scanning of the laser light of the input optical system and writing of the image input to the spatial light modulation element; a high-intensity light source; and an optical system for reading and enlarging and projecting the image written on the spatial light modulation element using light from the spatial light modulator.