JPH11133402A - Liquid crystal shutter and optical printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress an ooze-out phenomenon of light occurring from a boundary of light/dark parts of an image toward a dark part and to obtain a high quality output image faithful to an image input signal by shielding light transmission of only a fringe part of a liquid crystal layer sealed in a gap between parallel slender glass substrates with a mask member. SOLUTION: A housing window part 56 is provided on a case made of resin of an optical unit 5. Further, a mask window part 571 provided on a mask member 57 arranged on a liquid crystal shutter array 55 is opened on a part parting by 2 mm from frame like seal material 553 printed on the lower glass substrate of the liquid crystal shutter array 55, and a width of an effective pixel area 5574 transmitting light through is made a nearly 2 mm of its central part for the width nearly 6 mm of the whole pixel area, and the ratio of the widths is made nearly 3:1. Further, the left/right ends (both ends in the line direction) of the effective pixel are separated by >=1 mm from the seal material 553. Thus, the light transmitting through the fringe part is eliminated substantially, and the ooze-out of the light from bright pixel is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal shutter array and an optical printer device having the liquid crystal shutter array as an important component.

[0002]

2. Description of the Related Art A conventional liquid crystal shutter array is an elongated liquid crystal cell in which N electrodes are arranged in a direction perpendicular to the longitudinal direction, and pixels are formed by at least n electrodes. On the other hand, one line of an image or character information to be input is divided into at least N dots, and a voltage applied to an electrode corresponding to each pixel is controlled so that the light transmittance of each pixel corresponds to the density of each dot of the input image. It is used to display and output an image on another photosensitive material or the like.

An optical printer device is a device for forming an image by scanning a light beam of which intensity is controlled on a photosensitive paper surface in a broad sense. The optical printer related to the present invention employs the liquid crystal shutter array described above. The entire surface of the liquid crystal is irradiated with light, and the control circuit controls the light transmission of each pixel of the liquid crystal shutter array to irradiate one line of controlled light on the photosensitive surface, and further scans the photosensitive surface in a direction perpendicular to the image line. This is a device for forming an image on a photosensitive surface by successively exposing the line output of the image while forming the image, and is used as an image output terminal device of a computer.

A conventional optical printer is described in detail in, for example, Japanese Patent Application Laid-Open No. 2-169270. According to this publication, a long linear fluorescent tube is used as a light source, and an optical path is used to form an image of the linear light source as a bright line on a photosensitive surface using a cylindrical lens. Further, the image is mechanically scanned on the photosensitive surface. Also disclosed is a device in which a liquid crystal shutter array for decomposing the bright line into dot pixels is inserted in the optical path and is exposed on a photosensitive surface while controlling light to form an image.

The principle of obtaining a color image is as follows. A color separation liquid crystal shutter with a three-color filter for separating a white light source into three R, G, and B lights arranged adjacent to each other and sequentially transmitting the light with a time difference between the lights of each color. Are provided (on the side of the light source) further in front of the liquid crystal shutter array that controls light in pixel units. The light source images of the respective colors are formed as three adjacent bright lines of different colors on the (fixed) photosensitive surface, but are actually located at the same position on the photosensitive surface by the time difference transmission and the scanning at a constant speed. Each color is sequentially exposed so as to overlap. The light transmission amount of each color light is controlled for each pixel by the liquid crystal shutter array. This operation is repeated for each line. Therefore, if a color photosensitive paper is placed at the position of the photosensitive surface, a color print can be obtained.

The present applicant has made various improvements to improve the quality of an image in an optical printer device, but finally arrived at a structure as shown in FIG. FIG. 1 is a plan view of a main part showing a structure of an optical printer device of the present invention to which the liquid crystal shutter array of the present invention is applied, and FIG. 2 is a central sectional view thereof.

In FIGS. 1 and 2, reference numeral 1 denotes a lower housing, which is an instant film as photosensitive paper 2, a developing roller 11 for developing a developer on the exposed film surface, and mechanical and optical devices. A control circuit 3 for controlling the operation is housed. Reference numeral 4 denotes an upper housing, which is an optical unit 5 which is a dark box which houses an optical system and is movable for scanning, a wire 61 for pulling it, and a driving mechanism 6 thereof (details are omitted).
And so on.

An LED unit 51 in which three color LEDs (R, G, and B three color LEDs are sequentially turned on at different times), which are light sources, are arranged close to each other in the vertical direction. Toroid lens 5 with lens surface
2. A parabolic mirror 53 that reflects a light beam 58 emitted from the light source in a fan shape as a parallel light beam, and the parallel light beam passes through the toroidal lens 52 again to form a sharp line at the distance of the photosensitive surface (specifically, close proximity (As three bright lines of R, G, B colors)
A flat reflecting mirror 54 that bends the converged light beam 58 downwardly by 90 ° toward the photosensitive paper 2 and emits it from the optical unit window 56, and a liquid crystal shutter array arranged in the light beam immediately before the window 56. 55 are arranged and supported.
The principle of obtaining a color image is the same as that of the conventional example, but since a separate LED is used as each color light source, there is no need for a liquid crystal shutter with a color filter for three-color separation, which simplifies the configuration and improves the imaging accuracy. ing.

With such a configuration, the sharpness of the linear light source image (bright line) on the photosensitive surface and the separability of the luminous flux in the direction of the light source image are significantly improved as compared with the prior art. Since the constant speed was strictly pursued, the control resolution of the liquid crystal shutter array 55 was significantly improved. For example, when the size of one pixel is 162 μm in length and width on the photosensitive surface and a color image of 640 dots / line × 480 lines is printed on an instant film, the image is taken directly by a photographic camera with the naked eye unless observed with a high magnification loupe. It has become possible to obtain images of high image quality that cannot be distinguished from images at all.

[0010] As the quality of the image obtained as described above is improved, a disadvantage that has been overlooked in the past has emerged. One is a problem related to the fidelity of an image obtained as an output on a photosensitive paper in response to an image input signal for controlling each pixel of the liquid crystal shutter array, and is a bleeding of an image in a horizontal direction of a line. FIG. 3 shows an example. FIG. 3 shows a bright small square 2 in a uniform gray or black background 21.
In the main part of the output image of the photosensitive paper when displaying the second image (regardless of the color, for example, white), a bright square color is blurred in the horizontal direction of the line (perpendicular to the scanning direction). 23 appears to have oozed out. This is a phenomenon that hinders the realization of an optical printer that attempts to obtain a high-fidelity, high-definition output image.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to suppress the bleeding phenomenon of light which occurs from the boundary between bright and dark portions of an image toward a dark portion and to obtain a high quality output image which is faithful to an image input signal. To provide an improved configuration of a liquid crystal shutter array, and to provide a high quality
Another object of the present invention is to provide a high-performance optical printer.

[0012]

In order to solve the above-mentioned problems, the present application has a liquid crystal layer sealed by a sealing material in a gap between at least two parallel elongated glass substrates, and has one inner surface of the glass substrate. Is provided with at least a transparent electrode for scanning, on the other inner surface of the glass substrate is provided a number of signal transparent electrodes at least along the longitudinal direction thereof, forming a pixel by the transparent electrodes, the glass substrate A liquid crystal shutter having a polarizing plate on the outside thereof, characterized in that a mask member for blocking light transmission at least in a region having a fringe portion of the liquid crystal layer is provided.

In addition, a liquid crystal layer sealed with a sealant is provided in a gap between at least two parallel elongated glass substrates, and at least one scanning transparent electrode is provided on one inner surface of the glass substrate. A liquid crystal shutter having a plurality of signal transparent electrodes provided on at least the other inner surface along a longitudinal direction thereof, forming pixels by the transparent electrodes, and a polarizing plate outside the glass substrate. A portion having a width of at least 2 mm from the inner edge of the liquid crystal layer toward the inside of the liquid crystal layer in a direction perpendicular to the longitudinal direction is regarded as an invalid pixel region, and a mask member for shielding light transmission so as to cover the invalid pixel region is provided. Features.

Further, the width of the effective pixel area excluding the invalid pixel area from the area occupied by the liquid crystal layer is set to about one third of the width of the liquid crystal layer.

The width of the effective pixel area excluding the invalid pixel area from the area occupied by the liquid crystal layer is about 2 mm, and the width of the liquid crystal layer is about three times the width of the effective pixel area. And

The width of the sealing material is about 0.8 mm.

Further, at least one of the glass substrates is further provided with a black mask for partitioning the pixels.

Further, the mask member is formed from an outer peripheral portion of the black mask.

Further, the mask member is a frame member provided near at least one surface of the liquid crystal shutter.

Further, the mask member is a member forming a part of a housing of the liquid crystal shutter.

Further, the black mask is formed of a linear thin film material which fills a gap between the plurality of signal transparent electrodes.

[0022] The invention is characterized in that both ends of the linear black mask are hidden behind a frame member of the mask member.

[0023] Further, a light beam spreading in a fan shape from the point light source is converted into parallel light by a parabolic mirror or the like, and the light is converged by a lens or the like on a photosensitive surface in a bright line shape. And a liquid crystal shutter having a pixel row parallel to the liquid crystal shutter is inserted and arranged. The liquid crystal shutter has a liquid crystal layer sealed by a sealing material in a gap between two parallel elongated glass substrates,
The one glass substrate is provided with a scanning transparent electrode on the liquid crystal layer side surface, and the other glass substrate is provided with a large number of signal transparent electrodes along the longitudinal direction on the liquid crystal layer side surface, It has a basic configuration in which a pixel is formed by the two transparent electrodes, and at least 2 mm of at least a region having a fringe portion of the liquid crystal layer or an inner edge of the sealing material toward the inside of the liquid crystal layer in a direction perpendicular to the longitudinal direction. An area is defined as an invalid pixel area, and a mask member that blocks transmission of the light in at least the invalid pixel area is provided, and an image signal is supplied to the liquid crystal shutter to control light transmitted through an effective portion of the pixel. An input image is formed on the photosensitive surface by scanning a bright line on the photosensitive surface in a direction perpendicular to the bright line.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The causes of the light bleeding phenomenon described above have been investigated in various ways. However, it has been clarified that the causes of the light bleeding are ultimately caused by the operation characteristics of the liquid crystal in the liquid crystal shutter array as described below. FIG. 4 is an exploded perspective view showing the structure of the liquid crystal shutter array, and FIG. 5 is a plan view showing the behavior of the liquid crystal during operation of the liquid crystal shutter array. In FIG. 4, reference numeral 551 denotes a lower glass substrate, 552 denotes an upper glass substrate, 553 denotes a frame-shaped sealing material printed on the upper surface of the lower glass substrate, and 554 denotes a liquid crystal injection hole provided in a part of the sealing material. The inner surfaces of both substrates are naturally subjected to an orientation treatment (not shown) after the electrodes are formed. The upper glass substrate 552 is accurately laminated on the lower glass substrate 551 and pressed, and the sealing material 553 is cured to form a liquid crystal sealing space between the upper glass substrate and the lower glass substrate.

Reference numeral 555 denotes a liquid crystal layer sealed in the liquid crystal sealing space, for example, made of an STN (super twisted nematic) liquid crystal material. The injection hole 5 is formed in a space having a thickness of, for example, about 5 μm surrounded by the sealing material in a vacuum.
A liquid crystal material is injected from 54, and then the injection hole is sealed. Reference numeral 556 denotes a scanning-side transparent electrode provided on the upper surface of the lower glass substrate (in this case, one line, covering almost the entire surface of the liquid crystal layer). 557 denotes a signal-side transparent electrode provided on the lower surface of the upper glass substrate (the adjacent electrode). The gap is about 10 μm) and the liquid crystal layer 5
55 (for example, 640).
) And overlap with the scanning-side transparent electrode 556,
Each pixel constitutes one pixel.

On the upper surface of the upper glass substrate 552 and the lower surface of the lower glass substrate 551, a polarizing plate having a polarization axis direction corresponding to the twist angle of the liquid crystal is adhered, but these are not shown. The signal-side transparent electrodes 557 are connected to output terminals of several driver ICs (not shown) mounted on the lower surface of the upper glass substrate and outside the sealing material. The input terminal of each driver IC is connected to an FPC (flexible printed circuit board, not shown), and receives an image signal from the control circuit 3 of FIG. Reference numeral 558 denotes a black mask formed of a large number of linear chromium deposition films formed on the upper surface of the lower glass substrate 551 together with the signal-side transparent electrodes 557, and has a width of 20 μm.
m, the pitch is 162 μm, which functions to shield the gap between adjacent pixels from light leakage and to increase contrast.
As the black matrix, a pigment or a dye, which is a black material made of an inorganic material or an organic material, is used. For example, carbon black.

In FIG. 5, reference numeral 5570 denotes an entire pixel area of the liquid crystal shutter array, which is an inner portion of the sealing material 553. A white selection signal, that is, a voltage waveform that maximizes the light transmittance, is given to a part of the series, that is, a series of several tens of white selection pixel groups 5571. Gray selection pixel group 5 on both sides
At 572, a gray selection signal, i.e., a voltage waveform having an intermediate light transmittance, is provided. In this state, when the behavior of the liquid crystal is observed in detail, when the behavior of the liquid crystal is observed in the gray-selection pixel group 5572, which is closer to the white-selection pixel and substantially equal to 3
An angular portion was present, in which light transmittance was uneven, and small portions having high transmittance were mixed. When the distance X (mm) from the inner edge of the sealing material 553 and the length Y (mm) of the fringe portion were actually measured, the relationship was as shown in the graph of FIG. It was found that the length decreased, and it became almost unrecognizable (┤0 mm) at a distance of 2 mm.

Since the position of the liquid crystal shutter array 55 is just before the focal point of the toroidal lens 52, the luminous flux from the LED of the light source is not sufficiently focused yet, and the length of the pixels of the liquid crystal shutter array 55 (the width of the entire pixel area 5570, That is, it has a width close to the length of the optical unit 5 in the scanning direction). Therefore, in a gray selection pixel mixed with light that has passed through the fringe portion 5573, the total light amount of gray dots formed at the focal point is increased, and the dots are made brighter than they should be. The brightness approaches a normal value because the area ratio of the fringe portion in the pixel decreases as the distance from the white selection portion increases. This is considered to be the reason that light bleeds appear in the output image. Therefore, in order to eliminate light bleeding, a pixel region that hardly includes a fringe portion is set as an effective pixel region 5574, and only this portion is used as an optical shutter, and a pixel region outside the pixel region is regarded as an invalid pixel region 5575, and light is blocked. And do not use it.

The cause of the fringe portion 5573 is as follows.
In the vicinity of the sealing material, the gas generated when the epoxy resin of the sealing material is thermally cured disturbs the alignment treatment film on the glass substrate. This is because it is easily affected by the drive voltage of the selected pixel. Further, during the sealing operation of the upper and lower glass substrates, a part of the sealing material scatters inside and also disturbs the orientation, but the scattering amount is smaller when the width Z (FIG. 5) of the sealing material 553 is smaller. For example, when Z = 0.8 mm instead of the conventional Z = 1 mm, the fringe portion 557 is formed.
The area of 3 was significantly reduced.

FIG. 7 is an exploded perspective view of an example of the embodiment of the present invention based on the above experiments and considerations. A mask member 57 is arranged on the liquid crystal shutter array 55. Reference numeral 56 denotes a housing window, which is a window provided on the resin case of the optical unit 5. The mask window portion 571 is opened at a portion more than 2 mm from the sealing material 553 to shield the fringe portion from light. Therefore, the width of the effective pixel region through which light can pass is about 6 mm for the entire pixel region 5570. It is about 2 mm at the center and its width ratio is about 3: 1. Also, the width of the seal member is set to Z = 0.8 mm to be narrow. Note that the left and right ends (both ends in the line direction) of the effective pixel should be separated from the sealing material by 1 mm or more, preferably close to 2 mm. It can be easily understood from the above description that such a configuration effectively eliminates the light beam passing through the fringe portion and does not cause light bleeding from bright pixels. In this embodiment, when a part of the housing holding the liquid crystal shutter array 55 (for example, a part of the internal structure of the resin case of the optical unit 5 which is a dark box) is used, the mask member 57 is completely formed. It is suitable for molding with black resin, has a small number of parts, and simplifies the assembly operation. That is, in this case, the light shielding at the boundary between adjacent pixels is
This is an efficient configuration in which a black mask 558 of a linear chromium thin film having both ends extended to the rear of the mask member 57 is used, and light shielding of a peripheral invalid pixel region is performed by the housing.

Although one embodiment of the present invention has been described above, the present invention is, of course, not limited to this embodiment. For example, an independent mask plate is used in which at least a part or all of the light blocking of the invalid pixel area of the liquid crystal shutter array is provided not on the housing but on the liquid crystal shutter array, or in the width direction (scanning direction) of the chrome black mask. A liquid crystal material that provides a wide frame-shaped portion on the outside and uses an opening (consisting of a number of openings sequentially adjacent in the line direction) only as an effective pixel area portion to eliminate or simplify an external mask. And adopting other embodiments such as changing the material of the sealing material, leaving the fringe portion in the mask to the extent that there is no practical problem, or changing the configuration of the optical printer using the liquid crystal shutter array of the present invention. Can be. Further, the optical shutter array of the present invention can be applied not only to an optical printer but also to, for example, a facsimile and other information devices, and can provide a corresponding effect.

[0032]

According to the present invention, only the effective pixel area is used as an optical shutter by using a mask member for shielding a fringe portion in a liquid crystal shutter array.
The bleeding phenomenon of the output image is eliminated, the unevenness of light and the contrast are particularly improved, and an output image that is faithful to the image input signal and has high quality can be obtained. Further, it is possible to provide a high quality and high performance optical printer equipped with the liquid crystal shutter array. Furthermore, when the mask member is a part of the housing of the liquid crystal shutter array, or when integrated with a black mask that shields the pixel boundaries, effects such as suppression of an increase in the number of parts, improvement of positioning accuracy, and reduction of the number of assembly steps are achieved. Is also obtained.

[Brief description of the drawings]

FIG. 1 is a main part plan view showing a structure of an optical printer device to which the present invention is applied.

FIG. 2 is a sectional view showing the structure of the optical printer device of FIG.

FIG. 3 is a conceptual diagram of an output image showing a problem of the conventional example.

FIG. 4 is an exploded perspective view showing a structure of a liquid crystal shutter array.

FIG. 5 is a main part plan view showing a fringe portion in the liquid crystal shutter array.

FIG. 6 is a graph showing the result of measuring the existing range of a fringe portion.

FIG. 7 is an exploded perspective view of an example of the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 21 background portion 22 small square 23 blur portion 55 liquid crystal shutter array 551 lower glass substrate 552 upper glass substrate 553 sealing material 555 liquid crystal layer 556 scanning side transparent electrode 557 signal side transparent electrode 5570 whole pixel area 5571 white selection pixel group 5572 gray selection pixel Group 5573 Fringe part 5574 Effective pixel area 5575 Invalid pixel area 558 Black mask 56 Housing window 57 Mask member 571 Mask window 58 Light ray

Claims (12)

[Claims] 1. A liquid crystal layer sealed by a sealing material in a gap between at least two parallel elongated glass substrates,
One inner surface of the glass substrate is provided with at least a scanning transparent electrode, and the other inner surface of the glass substrate is provided with a large number of signal transparent electrodes at least along its longitudinal direction. A liquid crystal shutter having a polarizing plate outside the glass substrate, wherein a mask member for blocking light transmission at least in a region having a fringe portion of the liquid crystal layer is provided. 2. A liquid crystal layer sealed by a sealing material in a gap between at least two parallel elongated glass substrates,
One inner surface of the glass substrate is provided with at least a scanning transparent electrode, and the other inner surface of the glass substrate is provided with a large number of signal transparent electrodes at least along its longitudinal direction. In a liquid crystal shutter having a polarizing plate outside the glass substrate, a portion having a width of at least 2 mm from the inner edge of the sealing material toward the inside of the liquid crystal layer in a direction perpendicular to the longitudinal direction is regarded as an invalid pixel region. A liquid crystal shutter provided with a mask member for shielding light transmission so as to cover the invalid pixel region. 3. The liquid crystal according to claim 2, wherein the width of the effective pixel area excluding the invalid pixel area from the area occupied by the liquid crystal layer is about one third of the width of the liquid crystal layer. Shutter. 4. The width of an effective pixel area excluding the invalid pixel area from the area occupied by the liquid crystal layer is about 2 mm. Therefore, the width of the liquid crystal layer is about three times the width of the effective pixel area. 3. The liquid crystal shutter according to claim 2, wherein: 5. The liquid crystal shutter according to claim 1, wherein the width of the sealing material is about 0.8 mm. 6. The liquid crystal shutter according to claim 1, wherein at least one of the glass substrates is further provided with a black mask for partitioning the pixels. 7. The liquid crystal shutter according to claim 6, wherein the mask member is formed from an outer peripheral portion of the black mask. 8. The liquid crystal shutter according to claim 1, wherein the mask member is a frame member provided near at least one surface of the liquid crystal shutter. 9. The liquid crystal shutter according to claim 1, wherein the mask member is a member forming a part of a housing of the liquid crystal shutter. 10. The liquid crystal shutter according to claim 1, wherein the black mask is formed of a linear thin film material that fills a gap between the plurality of signal transparent electrodes. 11. The liquid crystal shutter according to claim 9, wherein both ends of the linear black mask are hidden behind a frame member of the mask member. 12. A light beam spreading in a fan shape from a point light source is converted into parallel light by a parabolic mirror or the like, and the light is converged by a lens or the like on a photosensitive surface in a bright line shape. A liquid crystal shutter having a pixel row parallel to the image is inserted and disposed, the liquid crystal shutter has a liquid crystal layer sealed by a sealant in a gap between two parallel elongated glass substrates, and the liquid crystal shutter of the one glass substrate is provided. The surface on the layer side is provided with a scanning transparent electrode, and the surface on the liquid crystal layer side of the other glass substrate is provided with a large number of signal transparent electrodes along the longitudinal direction thereof, and a pixel is formed by the two transparent electrodes. The formed basic configuration, at least a region having a fringe portion of the liquid crystal layer or a region of at least 2 mm from the inner edge of the sealing material to the inside of the liquid crystal layer in a direction perpendicular to the longitudinal direction as an invalid pixel region, At least Also provided is a mask member for blocking the transmission of the light in the invalid pixel area, and applying an image signal to the liquid crystal shutter to control the light transmitted through the effective portion of the pixel, thereby forming a bright line on the photosensitive surface. An optical printer device, wherein an input image is formed on the photosensitive surface by scanning in a direction perpendicular to the bright line.