JPS6256925A - Liquid crystal display printing device - Google Patents

Abstract

PURPOSE:To make a TV display of high resolution and also to perform screen projection and image copying by a photosensitive body through a simple constitution by imposing intensity modulation upon the luminous flux of a linear light source by a liquid crystal shutter, and writing an image on a liquid crystal panel and forming a latent image on the photosensitive body. CONSTITUTION:The luminous flux 2 of the linear light source 1 is intensity- modulated by the liquid crystal optical shutter 3 into luminous flux 2', which is reflected by a rotary polygon mirror 4 to write an image on the liquid crystal panel 5, so that the image is projected on a screen 7 through a projection optical system 12. Part 2'' of the luminous flux, on the other hand, is reflected by a mirror 8 and converged on the photosensitive body 9 to transfer and fix a visible image on paper 11. Therefore, the TV display and screen display of high resolution become possible even when the shutter 3 which operates at a high speed is used, a display screen can be copied when necessary, and the liquid crystal shutter 3 and liquid crystal panel 5 are inexpensive, so the device is manufactured at low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a liquid crystal display printing device having both functions of projection-type image display and electrophotographic printing.

(Prior art and its problems) Projection type display devices are capable of displaying large screens;
Widespread demand is expected for educational purposes, conferences/lectures, entertainment, etc., and the method is also cathode
(RT) A method in which a display screen is directly projected by waves, a method in which an image written on an oil film is projected, etc. have been put into practical use. but,
The CR'l' method has the disadvantage that the screen is dark, and both methods have a common disadvantage that the equipment is extremely expensive. In recent years, a method using a liquid crystal display device has been actively researched as a new projection type large screen display method to overcome these drawbacks.

Liquid crystal display devices used for projection-type large-screen display have improved image writing methods, such as electric field writing type using matrix electrodes, CR
It is roughly divided into optical writing type using T and thermal writing type using laser. Among these, the heat-containing type has the common advantage of low cost, which is common to liquid crystal display devices, and also has excellent performance such as high resolution, and is a popular choice for research and development of projection type liquid crystal display devices. It has become the mainstream. This method scans a liquid crystal panel two-dimensionally while modulating the intensity of a laser beam, which is equipped with a light-absorbing film that absorbs 1/- laser light and converts it into heat. Based on this effect, a display image is written by utilizing the fact that the liquid crystal in a portion that has heated up due to irradiation with strong laser light enters a light scattering state. That is, 1--
Since the laser beam can be narrowed down extremely narrowly, it is possible to display high-resolution images, but the writing speed is slow because one screen is constructed by scanning the laser beam two-dimensionally, making it difficult to display moving images on TV screens, etc. It has the disadvantage that it cannot be used. On the other hand, the matrix electrode type electric field writing type and the CRT type optical writing type both have high-speed writing properties that can display moving images, but the former has a limit to high resolution due to the electrode formation. The resolution of the latter is also limited by the CRT screen, and it is not possible to obtain any high resolution with the laser heating 1-included type. Conventionally, it has not been possible to obtain a projection type liquid crystal display device that is capable of displaying moving images with high resolution, and it is impossible to perform, for example, large-screen high-definition TV display with a low-cost liquid crystal display device. Met.

On the other hand, there is a strong desire to make a hard copy of the display screen, and there is a strong desire to put into practical use a device that has both the functions of a display device and a printing device. This desire is reflected in the remarkable spread of electronic whiteboards in recent years. - As a conventional liquid crystal display printing device that integrates an electronic liquid crystal display device and a printing device, there is, for example, a small high-resolution projector/printer developed by the present inventors. This has a structure in which the aforementioned laser thermal writing type projection type liquid crystal display device and laser scanning type electrophotographic printing device are integrated. The details are described on pages 5-137 of Volume 5 of the 1985 IEICE Comprehensive National Conference Lecture Proceedings. However, this conventional liquid crystal display printing device has only one
Since it is a thermal writing method, it is not possible to display moving images such as on a TV screen as described above, and its purpose is to display still images such as conference materials and print the displayed images. Therefore, it has not been possible to print a hard copy of the display screen at any time on a large screen display device that is capable of displaying high definition TV.

(Object of the invention) Objective of the invention) A large screen projection display capable of displaying high-intensity images on a TV. You can also print
Another object of the present invention is to provide a liquid crystal display printing device that can be made low-ambiguous.

(Structure of the Invention) The liquid crystal display printing device of the present invention is a liquid crystal display device comprising a linear light source and a ferroelectric liquid crystal sandwiched between two substrates provided with transparent electrodes forming a one-dimensional pixel array. an optical shutter; a liquid crystal panel comprising a liquid crystal sandwiched between two electrode substrates, one of which has a photoconductor film; scanning means for scanning a part of the linear light flux spatially intensity-modulated onto the conductor film in a direction orthogonal to the one-dimensional direction; and a photosensitive drum that transfers an image onto a medium according to a latent image formed by an electro-optic effect according to the intensity distribution of a voltage applied to the liquid crystal of the liquid crystal panel produced by the photoconductive effect of the liquid crystal panel. Ru.

(Operation/Principle of the Invention) In order to explain the operation of the liquid crystal display printing device of the present invention, first, what is the liquid crystal light? Explain the movements and actions of Yatter.

FIG. 2 is a diagram illustrating the operation of the ferroelectric liquid crystal used in the liquid crystal optical shutter constituting the projection type liquid crystal device of the present invention. As shown in FIG. 2, liquid crystal molecules 22 having spontaneous polarization 21 take on a layered structure and at the same time form a helical structure. An example of such a liquid crystal is a type called a chiral smectic liquid crystal. In this state, the spontaneous polarization is uniformly distributed around the helical axis 23 and cancels each other out, but if this unconventional liquid crystal is sandwiched between two substrates parallel to the helical axis, and the gap between them, that is, the liquid crystal When the thickness is reduced to at least the pitch length of the helical structure, the liquid crystal molecules 22 are forced to align in one of two orientation states in which the spontaneous polarization 21 is perpendicular to the substrate.

Figure 3 is a diagram showing this situation, and region A is the spontaneous polarization 21.
is facing the lower substrate 31, region B is spontaneously polarized 21
is facing the upper substrate 32. Figure 4 shows the third
This is a diagram of the state shown in the figure viewed from the top surface of the substrate, and shows that the liquid crystal molecules in the region and region B have 41.42 different alignment states.

For example, the state shown in FIG. 4 is sandwiched between two polarizing plates whose polarization directions are direct to each other, and the polarization direction 43 of one polarizing plate is made to match the direction of the liquid crystal molecules in the alignment state 41. When observed, the area person appears dark and area B appears bright.

Although region B appears brightest, the direction of the liquid crystal molecules in alignment state 42 is in the middle direction between the polarization directions of the two polarizing plates (which are orthogonal to each other).

That is, 45 degrees from each of the polarization directions of the two polarizing plates.
It is easy to see that this is a case of deviation.

In this way, when a chiral smectic liquid crystal exhibiting ferroelectricity is sandwiched between two substrates with an extremely narrow gap, the liquid crystal molecules can take one of two optically recognized orientation states. Furthermore, the spontaneous polarization of the ferroelectric liquid crystal directly responds to an external electric field and aligns in the direction of the electric field. Therefore,
When a direct current electric field in a direction perpendicular to the substrate is applied from the outside and its direction is reversed, the direction of spontaneous polarization is reversed accordingly. That is, the region man and region B in FIG. 4 are electrically switched, and this can be easily realized by forming transparent electrodes or the like on the inner surfaces of the two substrates. Moreover, since this electrical switching phenomenon is due to a direct response between spontaneous polarization and an external electric field, it is extremely fast.
rs) Volume 36, No. 11 (published in 1980), 89
Noel Ni. Published from pages 9 to 901
Clark (NoelA, C1ark) and SvenT, Lagerwall
), a high-speed response on the order of microseconds has also been confirmed.

(Example) Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention. A light beam 2 emitted from a linear light source 1 in a direction perpendicular to the paper plane undergoes intensity modulation by a liquid crystal light shutter 3 to become a light beam 2', which is reflected by a rotating polygon mirror 4 and reaches a liquid crystal panel 5.

FIG. 5 is a front view of the liquid crystal optical shutter 3 shown in FIG.
The electrodes 53 and 54 formed on the two substrates 51 and 52 holding the ferroelectric liquid crystal are formed into the shape shown in the figure, for example, and are formed at the intersections of the 1 coffin 53 and the L and 54. The pixels 55 are arranged in a one-dimensional array (in the direction perpendicular to the plane of the paper in FIG. 1), and the light beam 2 from the glandular light source 1 parallel to the array of pixels 55 is made to enter the array of pixels 55. At the same time, by applying a signal voltage according to the image to each electrode 53 of this array of pixels 55, the linear light beam 2' that has passed through the array of pixels 55 is spatially intensity-modulated in one-dimensional direction. The operation of writing an image on the liquid crystal panel 5 by irradiating the sky with the linear light beam 2' subjected to strong modulation will be explained. Figure 6 is similar to Figure 1 (
(This is a cross-sectional view of the liquid crystal panel 5 shown. 61 and 62 are glass substrates, and transparent electrodes 63 and 64 are formed on their inner surfaces, and one substrate 61 has a photoconductor film 65. , a light-shielding film 66, and a mirror 67 are provided, and a liquid crystal 68 is placed in the gap between the two glass substrates 61 and 62.The liquid crystal 68 is a Neftic liquid crystal that operates in what is known as a hybrid field effect mode. The manufactured liquid crystal panel 5i is irradiated with the linear light beam 2 that has undergone one-dimensional spatial strong modulation in the direction perpendicular to the plane of the paper in FIG. The linear light beam 2 is scanned in the direction 71 below the screen while switching the signal on a line-by-line basis.

That is, a portion 2' of the light beam that has undergone intensity modulation and transmitted through the liquid crystal light shutter is reflected by the rotating polygon mirror 4 and is reflected by 4.
The light is focused on the photoconductor film of the liquid crystal panel 5 shown in FIG. The light beam 2' scans the photoconductor film from right to left in the drawing as the polygon mirror rotates.

A two-dimensional image is formed on the photoconductor film 65 of the liquid crystal panel 5 by scanning with this light beam 2'. Since the aforementioned liquid crystal light shutter 3 turns on and off extremely rapidly on the order of microseconds, it is easily possible, for example, to form a screen with 1000 scan lines in a frame time of 30 milliseconds using line sequential scanning. (In this case, the scanning time is 30 microseconds per line.) However, the image formed on the photoconductor film 65 in this way is reduced line-by-line, and cannot be visually recognized as a two-dimensional image as it is. The liquid crystal panel 5 is only for visualizing this image.

An AC voltage is applied to the entire surface of the liquid crystal layer of the liquid crystal panel by a power source 69 via electrodes 63 and 64. However, a photoconductor film 65 is inserted between the electrodes 63 and 64 in series with the liquid crystal 680 layer, and this film 65 has a higher resistance than the liquid crystal in a dark state where it is not exposed to light. Externally applied voltage does not act on the liquid crystal.

However, corresponding to the image formed on the photoconductor film 65 as described above, the portions irradiated with light are exposed to the photoconductor film 65.
5 has a low resistance partially, and the liquid crystal 6 corresponding to this part
An external voltage acts on B. In this way, the bright and dark image formed on the photoconductor film 65 is
8 is converted into an intensity distribution image, and in response, the liquid crystal 68 forms a visible image using a known electro-optic effect.

The example hybrid field effect mode exhibits a cumulative response in response to rapid changes in applied voltage, and takes advantage of the afterimage effect to
The image formed on the liquid crystal layer of the liquid crystal panel 5 can also be visually recognized by line-sequential refresh writing. It goes without saying that a visible image can be formed on a liquid crystal panel even by using the electro-optic effect of the high-speed memory deafness of the ferroelectric liquid crystal described above, in addition to the cumulative effect and afterimage effect, and the operation of the liquid crystal used in the liquid crystal panel You can use whatever mode you want.

In this embodiment, the image thus formed on the liquid crystal panel 5 is projected onto the screen 7 using a normal projection optical system 12 using the xenon lamp 6 shown in FIG. 1 as a light source. The liquid crystal panel 5 shown in FIG. 6 includes a mirror 67 that reflects the projection light 72 and a light shielding film 66 that prevents the projection light from being irradiated onto the photoconductor film and causing malfunction.

On the other hand, part 2 of the light flux that has been intensity-modulated by the liquid crystal optical shutter
" is reflected by the mirror 8 and focused on the surface of the photoconductor drum 90. Since the tone photoconductor drum 9 is rotating at high speed, it is the same two-dimensional light as that formed on the photoconductor YGs of the liquid crystal panel 5. An optical image is also formed on the photoconductor film of the photosensitive drum 9, and as the photoconductor in the irradiated area becomes conductive, it is converted into an image with an electric to7 distribution. The J image formed on the surface of the photosensitive drum 9 is coated with toner 10 as the drum rotates 90 times, and becomes an image ↓ on the toner 10, which is transferred onto the surface of the paper 11 that is moving in contact with the drum 9. The image is then fixed and printed.

In this embodiment, by using a liquid crystal optical shutter 3 capable of high-speed operation, it is possible to write images line-by-line at high speed 9, and display moving images like a TV screen. Since both the number of pixels and the number of scanning lines can be sufficiently increased, high-resolution display is possible. Needless to say, the size of the display screen can be arbitrarily set since it is a projection type. Further, it is well known that optical elements such as the liquid crystal optical shutter 3 and the liquid crystal panel 5 can be manufactured at extremely low cost, and the cost can be sufficiently reduced.

In this embodiment, the arrangement of pixels 55 of the liquid crystal light shutter 3 is 166 pixels per millimeter, and 1024 pixels are formed over a length of about 64 mm, and 8 pixels are arranged for the purpose of reducing the number of drive circuit elements and lowering the cost. Each pixel forms a pixel group, and time-division driving with a so-called 1/8 duty is performed.

Since the driving time per pixel is 4 microseconds, the driving time of all pixels is 32 microseconds.

The scanning length of the light beam 2' on the photoconductor film 65 due to the rotation of the rotating polygon mirror 4 is approximately 64 mm, the norm time is 33 milliseconds, and the required driving time per scan line is 32 microseconds. , 1024 scanned lines are possible. That is, 1024X10 with a frame time of 33 ms.
Writing of 24 pixels is possible, and high-definition TV screen display is possible.

The light guide/four-body film 65 of the liquid crystal panel 5 of this embodiment is a cadmium sulfide film, the light shielding film 66 is a cadmium telluride film, and the mirror 67 is a dielectric mirror.

Further, to be more specific, the liquid crystal of this actual tS example is a normal twisted nematic liquid crystal and operates in a hybrid field effect mode. Therefore, although a polarizer is attached to the liquid crystal panel 5, it is omitted from the drawing. This also applies to the liquid crystal light shutter 3. The response speed of image display on the liquid crystal panel 5 of this embodiment is approximately 30 milliseconds.

The displayed image is projected onto a 1.5 meter square screen 7 by a projection optical system using a SOOW xenon lamp 6 as a light source. The brightness on the screen is about 300
footlambert, and the display contrast is 5:1.

The photoconductor film of the photoreceptor drum 9 in this embodiment is also made of cadmium sulfide, and the exposure time only needs to be 1.5 microseconds or more. Although it can be formed in the same 33 milliseconds per page, the printing speed is 1 second per sheet as a result of being limited by the fixing speed. This speed is sufficient as a printing speed, and an extremely high quality hard copy of 16 dots/mm can be obtained.

(Effects of the Invention) As described above, according to the present invention, high-resolution TV display is possible at the same time as large-screen projection type display.

It is possible to obtain a liquid crystal display printing device that can print hard copies as needed and can be manufactured at a low cost.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a schematic diagram showing a helical arrangement state formed by liquid crystal molecules of a ferroelectric liquid crystal used in a liquid crystal optical shutter, and Figs. 3 and 4 are FIG. 5 is a front view of the liquid crystal optical shutter shown in FIG. 1, and FIG. 6 is shown in FIG. 1. 5 is a cross-sectional view of a liquid crystal panel 5. FIG. In the figure, 1 is a linear light source, 2, 2', and 2'' are luminous fluxes. 11 is paper, 21 is spontaneous separation, 22 is liquid crystal molecules, 23 is a helical axis, 31.32 is a substrate, and 41.42 are liquid crystal molecules. 43 is one of the two orthogonal polarizing plates.
51° 52 is a glass substrate, 53.54 is a transparent electrode, 55 is a pixel, 61.62 is a glass substrate, 63
．． 64 is a transparent electrode, 65 is a photoconductor film, 66 is a light shielding film,
67 is a mirror, 68 is a liquid crystal, 69 is a power supply, 71 is a luminous flux 2
72 represents the projection light. Agent Patent Attorney Gomoku Uchihara. Part 1 @ Ne 2 @ ヮと〜BI1-)+ 3rd Part 4 Figure 5 Figure 6 Rate

Claims (1)

[Claims] A liquid crystal optical shutter consisting of a ferroelectric liquid crystal sandwiched between two substrates provided with linear light beams and transparent electrodes forming a one-dimensional pixel array, and a photoconductor film provided on one of the substrates. A liquid crystal panel comprising a liquid crystal sandwiched between two electrode substrates, and a part of the linear light beam emitted from the linear light source and spatially intensity-modulated in one dimension by the liquid crystal light shutter are connected to the conductor. a scanning means that scans the body membrane in a direction perpendicular to the one-dimensional direction; and a voltage applied to the liquid crystal of the liquid crystal panel that is caused by a part of the linear light velocity due to the photoconductive effect of the photoconductor film. a projection unit that projects an image formed on the liquid crystal by an electro-optic effect according to an intensity distribution onto a screen; and a photosensitive drum that transfers an image onto a medium according to a latent image formed by the remainder of the linear light velocity that is irradiated. A liquid crystal display printing device comprising: