JPH0584489B2 - - Google Patents

Description

[Detailed description of the invention]

Description will be made in the following order A. Industrial field of application B. Outline of the invention C. Prior art D. Problem to be solved by the invention E. Means for solving the problem (Fig. 1) F. Effect G. Example (Fig. 1) (Figure 1) H Effect of the invention A Industrial field of application The present invention relates to a display device. B. Summary of the Invention The present invention provides a display device in which an image is written and displayed on a liquid crystal cell using a laser beam, in which the liquid crystal cell is exposed to a reading laser beam using the same scanning system as that used for writing. By scanning the liquid crystal cell, the image written in the liquid crystal cell can be read out as data. C. Prior Art First, an example of a liquid crystal display device will be explained with reference to FIG. This liquid crystal display device writes a display image on a liquid crystal cell by irradiating the liquid crystal cell with a laser beam, and displays the image by enlarging and projecting the image onto a screen using a projection means. Note that the image has two levels of density: white or black. 10 indicates the liquid crystal cell, which is
When a laser beam is irradiated, the laser beam is converted into thermal energy and the irradiated area is heated. This heating causes a phase transition in the liquid crystal and the alignment state is disturbed. When the laser beam is stopped, the irradiated area is heated. The liquid crystal is rapidly cooled, and the disordered arrangement of the liquid crystals remains, so that the irradiated area becomes opaque. For this reason, the liquid crystal cell 10 is configured as shown in FIG. 3, for example. That is, in the figure, numeral 11 is a liquid crystal filled in a layered manner, and alignment layers 12 and 13 and transparent electrodes 14 and 15 are provided on both sides of the liquid crystal.
is provided. This electrode 14 is a glass plate 16
The electrode 15 is formed on a glass plate 17. The laser beam for writing is irradiated from the glass plate 16 side, and the projection light from the projection means is projected from the glass plate 17 side. Further, in this case, the liquid crystal 11 is a cyanobiphenyl liquid crystal, for example, a mixture of 40 mol% of octylcyanobiphenyl and 60 mol% of decylcyanobiphenyl. When absorbed, a phase transition occurs depending on the temperature: smectic A phase → nematic phase → isotropic phase. For example, the phase transition temperature from the smectic A phase to the nematic phase is 44.8°C, and the phase transition temperature from the nematic phase to the isotropic phase is 45.2°C. Furthermore, the liquid crystal 11 contains dyes such as 1,
3-(1,4-dimethyl-7-isopropylazulenyl)-cyclobutenediylium is added to increase the efficiency of laser light absorption and transmission. Further, as an example, the effective area of the liquid crystal cell 10 is 20 mm in height x 20 mm in width, and the resolution is 2000 pixels in height x 2000 pixels in width. Furthermore, in FIG. 2, reference numeral 20 indicates writing means using laser light. This writing means 20
The device turns on or off a laser beam for each pixel according to display data, and irradiates the liquid crystal cell 1 with the laser beam to write an image in the cell 1. That is, the microcomputer 70 described later
When the display data is taken out, this display data is supplied to the monostable multivibrator 21 and converted into a write pulse with a pulse width of 2.5 μsec per pixel, and this pulse is supplied to the laser diode 23 through the drive circuit 22. . This diode 23 is, for example, a GaLlAs semiconductor laser, which outputs near-infrared light with an output of 30 mW and a wavelength of 780 nm. Therefore, the diode 23 outputs laser light that is modulated on or off according to the display data, but this laser light is supplied to the liquid crystal cell 10 through the galvanometer mirror 24 → lens 25 → prism 26. Ru. In addition, liquid crystal cell 1
A cold filter 27 is provided on the back of the 0 to improve thermal efficiency by reflecting laser light. Further, in this case, the scanning means 30 scans the liquid crystal cell 10 with laser light. That is, this scan includes raster scan, vector scan, etc., and the microcomputer 70 sends a digital horizontal address signal A _x and vertical address signal Ay specifying the X and Y coordinates of the scan position (laser beam irradiation position).
are taken out, and these signals A _x and A _y are supplied to D/A converters 31 and 32 to be converted into analog signals, and then supplied to a horizontal scanner 35 and a vertical scanner 36 through drive circuits 33 and 34. The galvanometer mirror 24 is driven in the horizontal and vertical directions by the scanners 35 and 36, and laser light is irradiated on the coordinates of the liquid crystal cell 10 specified by the signals A _x and A _y . In this example, the resolution of the liquid crystal cell 10 is 2000 pixels vertically x 2000 pixels horizontally.
Since there are 2000 pixels, the signals A _x and A _y are each 11 bits. Furthermore, 41 indicates an erase circuit, which is controlled by a microcomputer 70 to generate an alternating voltage at a predetermined level.
ER is taken out, and this voltage ER is supplied to the electrodes 14 and 15 of the liquid crystal cell 10 to perform erasing. However, this erasing includes full erasing, which erases the entire surface of the cell 10, and partial erasing, which erases only a part of the cell 10, and these are performed as shown in the following table.

[Table] Note that in partial erasing, a low erasing voltage ER is supplied to the entire surface of the cell 10, and only the portion to be erased is irradiated with laser light. Further, 42 indicates a temperature control circuit, which allows the liquid crystal cell 10 to maintain a first phase transition temperature of 44.8 in steady state.
The liquid crystal 11 is maintained (biased) at 43.3° C., which is, for example, 1.5° C. lower than the normal temperature, so that the liquid crystal 11 is maintained in the smectic A phase state during normal operation. Furthermore, 50 indicates a projection means, by which the image on the liquid crystal cell 10 is enlarged and projected onto a screen 58. That is, projection light is extracted from a light source, for example, a 150W halogen lamp 51, and this projection light is passed through an infrared filter 52 → a condenser lens 5.
3 → UV filter 54 → Mirror 55 → Lens 5
The liquid crystal cell 10 is irradiated through the optical path 6, and the light transmitted through the cell 10 passes through the prism 26 and is irradiated onto the screen 58 by the projection lens 57. Therefore, the image written in the cell 10 is enlarged and displayed on the screen 58. In this example, the screen 58 is a display screen in the projection means 50 and is also integrated with the tablet board 61 of the tablet 60. Therefore, the screen 58 is configured as shown in FIG. 4, for example. ing. That is, in the same figure, 59 is a flat and transparent glass plate, and the surface on the projection light side is a frosted glass surface 59A and serves as a display screen 58.
On the surface opposite to the ground glass surface 59A, a plurality of transparent, striped electrodes 63 are arranged horizontally and separated from each other. Also, 6
Reference numeral 4 denotes a flat and transparent glass plate, and on the surface opposite to the glass plate 59, a plurality of transparent and striped electrodes 65 are vertically arranged and separated from each other. And these glass plates 59, 6
4 are closely connected with an insulating layer (not shown) in between to form a transparent tablet board 61. In addition,
The thickness of the glass plates 61 and 64 is, for example, 1 mm each.
The size, that is, the size of the screen 58 and the tablet board 61 is, for example, an A4 size. Furthermore, 66 is a tablet pen, the electrode (pen tip) of which is insulated from the grip, so that when a voltage (scan pulse) is supplied to the electrodes 63 and 65 of the tablet 61, it catches the electric field. has been done. Further, 70 indicates a microcomputer that performs various controls, 71 is its CPU, 72 is a ROM in which a control program is written, 73 is a RAM for a work area, 74 is an input port, and 75 and 76 are output ports. These circuits 72 to 76 are connected to the CPU 71 via a system bus 79.
Furthermore, a full keyboard 77 is connected to the CPU 71 through a bus 79, and a floppy disk device 79 is connected through a floppy disk controller: FDC78. When the writing mode is set by operating the keyboard 77, ER is set to 0, and a scan pulse for the tablet version is formed in the microcomputer 70. This pulse is sequentially supplied to the electrodes 14 and 15 through the port 75, and the scan is started. It will be done. At this time, when the tablet pen 66 is applied to the glass plate 64, a scan pulse is detected by the tablet pen 66, and this scan pulse is detected by the tablet pen 66.
The data is taken into the microcomputer 70 through the microcomputer 70. Then, the microcomputer 70 determines which electrode among the electrodes 14 and 15 the scan pulse detected by the tablet pen 66 was scanned, and from this determination result, the coordinates indicated by the tablet pen 66 are determined. are determined, and according to these coordinates, the address signals A _x , A _y
The signals A _x and A _y are supplied to the D/A converters 31 and 32 through the port 76, and display data is supplied to the multivibrator 21 from the port 76. Therefore, the corresponding pixel (coordinates) of the liquid crystal cell 10 is irradiated with laser light to make this pixel opaque, and this is projected onto the screen 58 by the projection means 50, so that
A black dot is displayed on the screen 58 at the position where the pen 66 is applied. When the tablet pen 66 draws on the tablet board 61 in this manner, dots are written in the corresponding portions of the cells 10, and the trajectory of the pen 66 is displayed on the screen 58. Furthermore, when the keyboard 77 is operated to enter the erase mode, the erase voltage ER is supplied to the cell 10 and the entire surface or a portion designated by the pen 66 is erased. Furthermore, when the execution of a program is designated from the keyboard 77, the floppy disk device 79
The corresponding program is loaded into the RAM 73 and executed, and graphs and the like of the execution results are written into the liquid crystal cell 10 and displayed on the screen 58. Thus, with this display device, various images can be written on the liquid crystal cell 10 and displayed on the screen 58 using the tablet 60 or software. It is also possible to erase or rewrite the image written on the liquid crystal cell 10, that is,
You can also edit it. Further, since the tablet board 61 is made transparent and closely integrated with the display screen 58, the drawing position and the display position coincide, and therefore, the operability is excellent. Further, since the tablet board 61 and the display screen 58 are flat plates and are thin with a thickness of 1 to 2 mm, there is almost no parallax between the drawing position of the tablet pen and the displayed locus. Furthermore, since the image written in the liquid crystal cell 10 is projected onto the screen 58 for display, the distortion of the displayed image is much smaller than that of an image displayed by a CRT, and the contrast, brightness, It is not affected by the earth's magnetism and therefore does not cause parallax. Furthermore, since the image on the liquid crystal cell 10 is projected onto the screen 58 using the light from the lamp 51 for display, flickering does not occur and there is almost no strain on the eyes of the operator. Furthermore, since it is possible to display on the A4 size screen 58 with a resolution of 2000 dots x 2000 dots, high resolution and high quality display can be achieved. (Reference: Specification and drawings of Japanese Patent Application No. 59-278509) D Problems to be Solved by the Invention However, in the above device, the liquid crystal cell 1
Although an image can be written in cell 10 and displayed on the screen 58, the image written in cell 10 cannot be read as data. Therefore, even if a sufficiently satisfactory image is displayed through repeated editing, it cannot be saved as new data. This invention solves these problems. E Means for Solving the Problems The present invention provides a liquid crystal cell 10 whose transmission state is changed by laser beam irradiation and whose transmission state is maintained as shown in FIG. A writing means 20 for writing an image on the cell 10 with a laser beam, and a scanning means 3 for controlling the irradiation position of the laser beam on the liquid crystal cell 10.
0, and a projection means 50 that projects and displays the image written in the liquid crystal cell 10 on a screen 58.
Then, the detection means 82 for detecting the laser light transmitted through the liquid crystal cell 10 and the writing means 20 are controlled to output laser light to the extent that the transmission state of the liquid crystal cell 10 does not change, and the scanning means 30 is controlled. Image data that outputs data corresponding to the image held in the liquid crystal cell by scanning a laser beam over the entire surface of the liquid crystal cell 10 and outputting the detection result of the detection means 82 in synchronization with this scan timing. Reading means 80
A display device characterized by comprising: and. F Effect The laser beam for reading the liquid crystal cell is scanned by the same scanning system as the writing scanning system, and the image written to the liquid crystal cell is converted into data and taken out, so a new scanning system for reading is required. There is no need to add anything, and images can be read out by adding the minimum necessary parts. G Embodiment FIG. 1 shows the state at the time of reading, and the lamp 51
is turned off and the cold filter 27 is removed. Further, the input power of the laser diode 23 is set to such a magnitude that writing cannot be performed, for example, 5 mW (30 mW during writing), and is not modulated. Then, by sequentially changing the address signals A _{x and} A _y , the laser light is directed to the liquid crystal cell 1.
The entire surface of 0 is raster scanned according to the NTSC standard, for example. Further, the mirror 55 is a dichroic mirror through which the laser beam can pass. Furthermore, reading means 80 are provided. That is, when the liquid crystal cell 10 is irradiated with laser light,
Some of them are cell 10, lens 56 and mirror 5.
A condenser lens 81 is provided behind the mirror 55, and a photodiode 82 as a detection means is provided at its focal position, and the output of this diode 82 is supplied to an interface 84 through an amplifier 83. . Further, a forming circuit 85 is provided, from which vertical and horizontal synchronizing pulses are taken out and supplied to the interface 84 and the microcomputer 70, and the address signals A _x and A _y are changed in synchronization with the synchronizing pulses. . According to such a configuration, the liquid crystal cell 10 is scanned by an unmodulated weak laser beam from the laser diode 23, that is, a reading laser beam, and the scanned laser beam is supplied to the photodiode 82. Therefore, the image data written in the cell 10 is obtained from the diode 82, and in this case, the scanning of the laser light is based on the NTSC method, so the image data is converted into an NTSC method brightness signal. Become. This signal is then supplied to an interface 84 through an amplifier 83, to which a synchronizing pulse from a forming circuit 85 is added and taken out as an output. Thus, according to the present invention, an image written in the liquid crystal cell 10 can be extracted as data (signal). Therefore, by repeatedly editing the image, it is possible to obtain a sufficiently satisfactory image and save it as a new image. In addition, since the extracted data can be rewritten into the cell 10, editing functions can be expanded and display capabilities can be expanded. In addition, in the above, the cell 10 is connected to the microcomputer 70.
In response to the resolution of
It is also possible to read out the image data by scanning the 0 image pixel by pixel, that is, with a resolution of 2000 pixels vertically x 2000 pixels horizontally, and write this read data to the display memory in bit correspondence. The data can also be saved in the floppy disk device 79. Further, instead of the tablet 60, a coordinate input means such as a mouse may be used. H Effects of the Invention According to the present invention, an image written in the liquid crystal cell 10 can be extracted as data (signal). Therefore, since the liquid crystal cell has the function of holding an image written by a laser beam by changing its transmission state, while looking at the screen on which the image written on the liquid crystal cell is projected, After sequentially adding and changing the images held on the liquid crystal cell, it is possible to retrieve the data corresponding to the final image, and as a result, after repeated editing, the image can be fully satisfied. You can then save this as a new image. In addition, since the extracted data can be rewritten into the cell 10, editing functions can be expanded and display capabilities can be expanded.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of an example of the present invention, and FIGS. 2 to 4 are sectional views for explaining the same. 10 is a liquid crystal cell, 20 is a writing means, 30 is a scanning means, 50 is a projection means, 60 is a tablet, 70 is a microcomputer, and 80 is a reading means.

Claims (1)

[Claims] 1. The transmission state changes by irradiation with laser light,
a liquid crystal cell whose transmission state is maintained; a writing means for writing an image on the liquid crystal cell with a laser beam; a scanning means for controlling the irradiation position of the laser beam on the liquid crystal cell; a projection means for projecting and displaying an image on a screen; a detection means for detecting the laser light transmitted through the liquid crystal cell; and a laser that controls the writing means to such an extent that the transmission state of the liquid crystal cell does not change. By outputting light, controlling the scanning means to scan the laser beam over the entire surface of the liquid crystal cell, and outputting the detection result of the detection means in synchronization with this scan timing, the liquid crystal cell is A display device comprising: image data reading means for outputting data corresponding to an image held in the display device.