JP2001264887A - Exposure device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact color exposure device performing exposure by accurately superimposing respective red, green and blue color light beams on consecutively moving photosensitive paper without generating irregular color and the blurring of a formed image. SOLUTION: An optical shutter 14 and a conversion means for converting the optical path of the light beam are arranged in a laminated state, and a light source emitting the red, green and blue light beams is arranged on the side of the conversion means. Then, the optical shutter is opened/closed according to image data synchronizing with the respective color light beams from the light source so as to perform exposure with the red, green and blue light beams for every area corresponding to each pixel onto the photosensitive paper.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus used for an optical printer, and more particularly, to an exposure apparatus capable of performing full-color printing on a photosensitive member.

[0002]

2. Description of the Related Art A liquid crystal shutter array having a large number of liquid crystal pixels will be described as an example of an optical shutter of an exposure apparatus. A method of writing a color image by turning on and off a liquid crystal pixel of a liquid crystal shutter array and irradiating a modulated color light of a plurality of colors on photosensitive paper is described in, for example,
No. 169270.

In this method, as shown in FIG. 6, a red (R), green (G), and blue (B) colors are provided in an optical system for linearly condensing a white light source 61 by a spherical lens 62. A color liquid crystal shutter 63 having three row shutters for transmitting light as components is disposed. Further, at a position where light is linearly focused, a black and white liquid crystal having a large number of pixel elements arranged in a line is provided. The shutter array 64 is arranged. Based on the above configuration, the pixel elements in the black and white liquid crystal shutter array are opened and closed according to each color information in synchronization with the opening and closing of each of the red, green, and blue liquid crystal row shutters. In addition, a liquid crystal shutter that opens and closes according to color information,
The writing time for one pixel line is the photosensitive paper 6 which is a photosensitive member.
4, and almost coincides with the travel time.

The advantage of the above method is that the printing can be performed in a short time because the photosensitive paper is continuously moved while maintaining high-precision color exposure. That is, the arrangement of the three row shutters that transmit red, green, and blue light is shifted with respect to the moving direction of the photosensitive paper.
The red, green, and blue colors condensed linearly on the black and white liquid crystal shutter array by a spherical lens because the distance between the black and white liquid crystal shutter array and the photosensitive paper when the photosensitive paper does not move The light is sequentially irradiated with a slight displacement on the photosensitive paper, but in reality, the three red, green and blue color lights selected sequentially are almost displaced on the photosensitive paper due to the continuous movement of the photosensitive paper. This is because multiple irradiation is performed without overlapping.

[0005]

However, the method disclosed in the above-mentioned publication also has a disadvantage in principle that defocusing occurs in a process in which light condensed linearly on a black and white liquid crystal shutter array reaches photosensitive paper. is there. If the focal length of the spherical lens is increased in order to reduce the defocus, the optical path length increases, and the size of the exposure apparatus including the optical system increases, and the cost also increases.

Accordingly, the present invention solves the above-mentioned problems, and achieves red, red, and black on a continuously moving photosensitive paper without defocus.
It is an object of the present invention to provide a low-cost and compact exposure apparatus that allows green and blue color light to be overexposed on the same point on photosensitive paper with high precision and enables high-quality, short-time printing.

[0007]

An exposure apparatus according to the present invention, which achieves the above object, comprises a conversion means for changing an optical path of light emission, and arranges this conversion means and an optical shutter in a stacked manner. The light source is arranged on the side.

[0008] The light source emits a plurality of color lights. More preferably, the conversion means has a rectangular shape, and it is desirable that light is incident on the side surface of the rectangular shape and emitted from the lower surface of the conversion means.

[0009]

According to the structure of the present invention, an optical shutter for controlling light emission and a conversion means for converting the light path of light emission are stacked, and the light source is arranged on the side of the conversion means. Therefore, the light source to the optical shutter can be set compactly, and a low-cost and compact exposure apparatus can be provided. As the converting means, for example, by using an acrylic rod having a rectangular shape, the light emitted from the light source incident from the side surface of the acrylic rod is emitted from the lower surface, and is incident on the optical shutter, thereby converting the light path of the emitted light. Is possible.

At this time, by using red, green, and blue color light as light emission, the moving distance of the photoconductor is obtained by multiplying the moving speed of the photoconductor by the opening / closing time of the pixel for each pixel column.
By setting the pixel pitches to be equal to the three pixel row pitches of green and blue, it becomes possible to superimpose red, green, and blue light on one picture element on photosensitive paper, and to achieve high image quality without color shift Can be provided.

Further, according to the structure of the present invention, a point light source for repeating red, green, and blue color lights in sequence with a time delay is provided as a light source, and a conversion means for converting the point light source into linear light is arranged. The conversion means and the optical shutter are arranged on a straight line, and light emitted from a light source arranged on the side passes through the conversion means and is irradiated from above the optical shutter. In addition, since a line image formed on an optical shutter array is formed on photosensitive paper using a selfoc lens array, the size and cost of an optical system that irradiates color light onto photosensitive paper from a halogen lamp point light source can be reduced. It is possible.

As the conversion means, a rectangular acrylic rod capable of converting a point light source into linear light can be used. That is, the size of the color liquid crystal shutter that separates the color of the halogen white light source only needs to cover the end surface of the acrylic rod, and is much smaller than the width of printing on photosensitive paper. The components of the color liquid crystal print head, such as a halogen light source, a color liquid crystal shutter for color separation, an acrylic rod, and a black-and-white liquid crystal shutter array as a light shutter, and a selfoc lens array almost all adhere along the optical path of light. Since the optical heads are arranged in a vertical direction and do not require a special optical path length for imaging and condensing light, a very compact and low-cost color optical writing head can be obtained.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic explanatory view showing an embodiment of the color exposure apparatus of the present invention. A light source in which white light from a halogen lamp point light source 11 is separated into red, green, and blue light by a color liquid crystal shutter 12 is used as a light source, and continuously enters the end face of an acrylic rod 13 as a conversion means with a time lag. I do. The acrylic rod has a rectangular shape as shown in the figure, and is covered with a reflective foil on which aluminum or the like is deposited except for the emission surface of light emission, and functions to efficiently convert light incident from the rod end surface into linear light. have. The acrylic rod and the black and white liquid crystal shutter array 14 as an optical shutter were stacked and arranged. Therefore, the monochrome shutter array 14
, Red, green, and blue linear lights are continuously irradiated with a time lag.

At this time, red and black are contained in the black and white shutter array.
There are three pixel columns corresponding to green and blue, respectively.
It is driven so that only specified color light can be transmitted. For example, when red linear light is emitted, only one pixel row corresponding to red can be transmitted, and the other two pixel rows are maintained in a dark state. The red, green, and blue linear lights modulated by the black and white liquid crystal shutter array are imaged by the SELFOC lens array 15 on photosensitive paper such as Spectra Instant Film manufactured by Polaroid. At this time, due to the relative movement of the photosensitive paper with respect to the monochrome liquid crystal shutter array, the red, green, and blue linear lights are sequentially exposed at the same location on the photosensitive paper, so that a high-quality print without color shift can be obtained. An image is obtained.

The above two types of liquid crystal shutters (color liquid crystal shutter 12, black-and-white liquid crystal shutter array 1)
4) In order to achieve a short print time,
A super-twisted nematic liquid crystal which responds at high speed in milliseconds by applying an AC voltage of about 0 kHz is used. FIG. 2 is a schematic view of a color liquid crystal shutter for separating white light into colors. The upper glass substrate 23 with a transparent electrode divided into three regions corresponding to red, green, and blue.
The liquid crystal layer 24 having a twist angle of 240 degrees and a 5.5-micron liquid crystal layer 24 is interposed between the entire lower glass substrate 25 with a transparent electrode and the upper polarizing plate 22 and the lower polarizing plate 22 so that the polarization axes are orthogonal to each other. A plate 26 is arranged, and further, a red (R), green (G), and blue (B) color shutter 21 is arranged on the upper polarizing plate 22.

The ratio of the area of the red (R), green (G), and blue (B) color shutters is adjusted according to the color sensitivity of the photosensitive paper, the color of the liquid crystal layer, the halogen light, and the like. In the example, the area is increased in the order of red, green, and blue to obtain a print image with good color balance. The above-described color liquid crystal shutter for separating colors has a small outer size of 1.2 cm square, and sequentially transmits red, green, and blue transmitted light to the end face of the acrylic rod every 3 milliseconds.

FIG. 3 is a schematic plan view showing a pixel arrangement of a monochrome liquid crystal shutter array for modulating red, green, and blue linear lights sequentially emitted from the acrylic rod every 3 milliseconds in accordance with a color signal. The intersection of the three signal electrodes 31 and the three scanning electrodes 32 forms 1920 140-micron black and white pixels. For 3 milliseconds when the red linear light is irradiated, only the pixels on the scan electrode T1 are modulated according to the image signal, and all the pixels on the scan electrodes T2 and T3 are set to a dark state. Next, for 3 milliseconds when the green linear light is irradiated, only the pixels on the scan electrode T2 are modulated, and the pixels on the scan electrodes T1 and T3 are set in a dark state. Lastly, only the pixels on the scan electrode T3 are modulated for 3 milliseconds when the blue linear light is irradiated, and the pixels on the scan electrodes T1 and T2 are set to a dark state.

The above-described repetition occurs on a monochrome liquid crystal shutter array that moves relative to the photosensitive paper every 3 milliseconds, and a full-color image is written. FIG. 4 shows actual driving waveforms for moving the pixels on the monochrome liquid crystal shutter array by the above-described operation. Signal electrodes (S1, S2, S3, ...)
In (), a zero voltage is applied every 3 milliseconds to select the bright state, and an AC waveform of 12 volts and 10 kHz is applied to select the dark state. If the ratio between the zero voltage period and the AC voltage period is changed within the selection time of 3 milliseconds, a halftone selection waveform is obtained.

On the other hand, three scanning electrodes (T1, T2, T
In 3), an AC voltage of 24 volts and a zero voltage are applied at a time ratio of 2 to 1 every 9 milliseconds, and the period of the zero voltage is shifted by 3 milliseconds in accordance with the order of each scanning electrode. This is because the pixel rows on the three scanning electrodes are sequentially selected every three milliseconds, and are applied through the signal electrodes. However, the image data can modulate the liquid crystal pixels only when the scanning electrode voltage is zero. is there. Conversely, when an AC voltage of 24 volts is applied, no matter what data signal is applied to the signal electrode, the voltage applied to the liquid crystal pixels becomes 12 volts or more, and the liquid crystal pixel is set to a dark state.

According to the above-described driving method, the red, green, and blue linear lights are sequentially modulated by the pixel columns on the three scanning electrodes in the black and white liquid crystal shutter array, and relatively move through the selfoc lens array. On the photosensitive paper without color shift. In a printing experiment using Spectra Instant Film manufactured by Polaroid, a full-color image print of 64 gradations of each color with 640 × 400 pixels could be formed in about 4 seconds.

The monochrome liquid crystal shutter array can be applied to a case where the number of pixel columns is three or more. For example, FIG.
As shown in the figure, four scanning electrodes 52 (T1, T2, T
3, T4) and many signal electrodes 51 (S1, S2, S
,...), The red (R) linear light is modulated by a combination of two scanning electrodes T1 and T2 and each signal electrode group, and green ( G) Color linear light is modulated by a combination of the scanning electrodes T2 and T3 and the signal electrode group, and blue (B) linear light is modulated by a combination of the scanning electrodes T3 and T4 and the signal electrode group. Do. This method can increase the light irradiation density when exposing each color linear light to the photosensitive paper, and is extremely effective when the intensity of the light source is weak.

[0022]

As described in the above embodiments, the exposure apparatus according to the present invention comprises a light source that repeats exposure of red, green and blue color lights sequentially with a time lag and a halogen lamp point light source. Since it is configured by arranging an acrylic rod that converts the color liquid crystal, a compact and low-cost color liquid crystal print head can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of an exposure apparatus of the present invention.

FIG. 2 is a schematic view showing an embodiment of a color liquid crystal shutter according to the present invention.

FIG. 3 is a schematic plan view showing an embodiment of a monochrome liquid crystal shutter array according to the present invention.

FIG. 4 is a driving waveform diagram of the monochrome liquid crystal shutter array according to the present invention.

FIG. 5 is a schematic plan view showing another embodiment of the monochrome liquid crystal shutter array according to the present invention.

FIG. 6 is a schematic view showing an embodiment of a conventional color liquid crystal printing apparatus.

[Explanation of symbols]

 Reference Signs List 11 halogen lamp 12 color liquid crystal shutter 13 acrylic rod 14 monochrome liquid crystal shutter array 15 selfoc lens array 16 photosensitive paper 21 color shutter 22 upper polarizing plate 23 upper glass substrate with transparent electrode 24 liquid crystal layer 25 lower glass substrate with transparent electrode 26 lower polarization Plate 31 signal electrode 32 scanning electrode 33 black and white pixel 51 signal electrode 52 scanning electrode 61 white light source 62 spherical lens 63 color liquid crystal shutter 64 black and white liquid crystal shutter 65 photosensitive paper

Claims (3)

[Claims] 1. An exposure apparatus for controlling light emission from a light source by an optical shutter and exposing the controlled light onto a photoreceptor, comprising: a conversion unit for converting an optical path of the light emission; While stacking and placing
An exposure apparatus, wherein the light source is arranged on a side of the conversion unit. 2. The exposure apparatus according to claim 1, wherein the light source emits a plurality of color lights of different colors. 3. The exposure apparatus according to claim 1, wherein the conversion unit has a rectangular shape, and emits light emitted from a side surface of the rectangular shape from a lower surface.