JPH04369633A - Image forming device - Google Patents

Abstract

PURPOSE:To provide a digital scanning system image forming device having high resolution, high harmoney, and high speed output at low cost. CONSTITUTION:A liquid crystal shutter 37 which is separated for red, green and blue(extra), and which is constituted of plural lines is irradiated with light, the open/close of the liquid crystal shutter is executed by a processing circuit whose center is a CPU, and a micro capsule paper is synchronously carried and superimposed exposing is executed, so that an outputted image having high image quality can be obtained. An extra shutter is used for sub exposing, white emphasis, and the correction of a faulty line. And a green shutter having bad transmittivity is positioned in the center of the liquid crystal shutter, so that efficiency is raised. Furthermore, the liquid crystal shutter is miniaturized by changing the light transmittivity of each line by using a voltage generating circuit and a light quantity adjusting filter. And the dot deviation of the exposing is eliminated by finely adjusting the carrying speed V of the micro capsule paper, the frame cycle Ft of the liquid crystal shutter, furthermore, the reading interval of an inputting device in a sub-scanning direction.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly to an exposure method for a copying machine or a printer using a photosensitive recording medium.

0002

2. Description of the Related Art As a specific example of a conventional exposure method, an analog exposure method is shown in FIG. FIG. 18 is a schematic diagram of a photosensitive and pressure sensitive copying machine, in which photosensitive paper consisting of a photosensitive pressure sensitive paper 12 (hereinafter referred to as microcapsule paper) and a color developing paper 28 (hereinafter referred to as recording paper) is used. Microcapsules are coated on the surface of the support of the microcapsule paper 12, and the microcapsules contain a dye precursor that reacts with a color developer described later. The surface of the support of the former recording paper 28 is coated with a color developer, which develops color by reacting with a dye precursor. Omitted.

[0003] Hereinafter, only the exposure portion of the copying machine 1 will be briefly explained. Below the original platen glass 2 in the upper part of the copying machine 1, a light source unit 5 including a halogen lamp 5a, a reflector 5b, a reflective mirror 8, etc. moves back and forth along a shaft 13 installed parallel to the original platen glass 2. possible. The light source unit 5 irradiates light in a line toward the document table glass 2 in a direction perpendicular to the movement direction. The irradiated light passes through the transparent document platen glass 2 and is reflected downward by the document 4 placed thereon.

[0004] A mirror section 9 having reflecting mirrors 9a and 9b is disposed below the document table glass 2 and is movable separately from the light source section 5, and the light reflected from the document 4 is reflected by the reflecting mirror. The light beams 8, 9a, and 9b are reflected in this order and guided in parallel to the moving direction of the light source section 5.

A projection lens 7, which is usually fixed, and a filter 6 for adjusting the color tone of the copied image are disposed below the document platen glass 2, and the light reflected by the reflection mirror 9b is The light enters the lens 7. The lens 7
The light projected by is reflected by reflection mirror groups 10a and 10b.

An exposure table 11 for exposing the microcapsule paper 12 is disposed on the right side of the reflection mirror 10b, and a reflection mirror 10c for switching the optical path is provided between the reflection mirror 10b and the exposure table 11. It is arranged. Therefore, while the light source section 5 moves along the axis 13,
By moving the microcapsule paper 12, image information on the document 4 is sequentially formed on the microcapsule paper 12.

[0007] In this way, by projecting light directly onto the copy document,
By directly forming an image on the photoreceptor with the reflected light, it is possible to obtain an image with high gradation and high resolution.

Furthermore, as a conventional digital image forming apparatus using a low-sensitivity photoreceptor as described above, a digital static exposure system using a liquid crystal shutter has been devised. FIG. 19 is a schematic diagram of a full color printer using the microcapsule paper of the above method. In FIG. 19, a printer 100 includes a liquid crystal exposure device 102,
It is configured such that a long microcapsule paper 12 as a photosensitive recording medium is conveyed through an exposure area 115 below the liquid crystal exposure device 102.

The liquid crystal exposure apparatus includes a halogen lamp 53 as a light source, a reflector 53a that reflects the light emitted from the halogen lamp, and a condenser that converts the emitted light from the halogen lamp 53 and the reflected light from the reflector 53a into parallel light. condenser lens 53b, infrared cut filter 54 that cuts infrared rays, condenser lens 53b
and a reflective mirror 8 as an optical path changing means that changes the optical path of light after passing through the infrared cut filter 54, and a filter 6R that separates the light reflected by this reflective mirror into a single color of red, green, or blue. , 6G, 6B, and an LCD shutter 37.

The light from the halogen lamp 53 becomes parallel light through the condenser lens 53b, and is passed through the infrared cut filter 5.
4 and enters the reflecting mirror 8. filter 6R,
6G and 6B are driven by a filter driving device (not shown), and a filter of a color corresponding to the image signal that controls the LCD shutter 37 is inserted into the optical path. The parallel light passing through the condenser lens 53b is incident on the reflection mirror 8 and reflected, and the reflected light is filtered through the filters 6R and 6.
G, 6B separates into red, green or blue monochrome, L
The configuration is such that the light passes through each liquid crystal pixel of the CD shutter 37 and is irradiated onto the microcapsule paper 12. A full-color image is formed on the microcapsule paper 12 by opening and closing the LCD shutter 37 for each color filter and each pixel as needed in accordance with the image signal. That is, by overlapping red, green, and blue exposure three times on the microcapsule paper 12, a latent image is formed that is approximately the size of the LCD shutter and has a resolution based on the number of pixels of the LCD shutter.

[0011]

[Problem to be Solved by the Invention] However, when using the conventional analog exposure method, variations in the sensitivity characteristics of the photosensitive recording medium are directly reflected in the output image, resulting in only output images with poor color reproducibility. There was a problem. Furthermore, even if corrections are made using color filters, etc., the colors of the entire output image will shift, and although it may be possible to approximate colors that are visually pleasing to some extent, it will not provide a fundamental solution to improving the color reproducibility of the output image. not present.

Furthermore, the analog exposure method has the problem that although it can be used as a copying machine, it cannot be used as a digital output device such as a printer.

Furthermore, when an analog exposure method is adopted as a copying machine, the photosensitive recording medium is directly exposed to light reflected from the copied original, so the light utilization efficiency is extremely low, especially when the sensitivity of the photosensitive recording medium is low. There was a problem in that the copying speed could not be increased.

When static exposure is performed on a photosensitive recording medium using a liquid crystal shutter as in the second prior art, it is possible to improve the color reproducibility of an output image by digital color correction processing. However, because of static exposure, the size of the liquid crystal and the fineness of the liquid crystal cells are directly reflected in the output image, making it difficult to increase the resolution or increase the output paper size. Furthermore, it is difficult to manufacture high-definition large-sized liquid crystal shutters, which increases the cost of the shutter, and if a large-sized liquid crystal shutter is used, the entire device must be larger. there were. .

The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a high-resolution, high-gradation, high-speed output, and to easily increase the copy output size. An object of the present invention is to provide a digital scanning type image forming apparatus at low cost.

[0016]

[Means for Solving the Problem] In order to achieve this object, the image forming apparatus of the invention of claim 1 is provided, in which each of three colors (for example, for red, green, and blue) has n lines (n>1). It is equipped with an optical shutter consisting of a shutter.

Further, in the image forming apparatus according to the second aspect of the invention, each color shutter of the optical shutter according to the first aspect of the invention includes a preliminary shutter.

In the image forming apparatus according to the third aspect of the present invention, in the first aspect of the present invention, a preliminary shutter having characteristics that do not match the transmission wavelength of each shutter for each color is provided.

In the image forming apparatus of the invention of claim 4, in the image forming apparatus of the invention of claim 1, the photosensitive recording medium includes:
It is provided with means for realizing gradation expression of n gradations for each color by repeatedly exposing red, green, and blue n times.

The image forming apparatus according to the invention according to claim 5 is the image forming apparatus according to the invention according to claim 1, further comprising means for independently setting the amplitude of the drive signal for each of the n lines. .

The image forming apparatus according to the invention according to claim 6 is the image forming apparatus according to the invention according to claim 1, further comprising means for changing the light transmittance of each of the n lines line by line using a light amount adjusting member. There is.

An image forming apparatus according to a seventh aspect of the present invention is characterized in that the shutter open time of each of the n lines is independently changed for each line in the image forming apparatus according to the first aspect.

Furthermore, in the image forming apparatus according to the first aspect of the invention, the opening time of each shutter of n lines can be independently changed for each line. Further, in this case, a plurality of means (four or less) of claims 4 to 7 may be used in combination.

Further, in the image forming apparatus according to the fifth to seventh aspects of the invention, the drive according to the fifth aspect of the invention is configured such that the amount of light irradiated onto the photosensitive recording medium changes by 2 to the m power (m: a positive number). Signal amplitude, light amount adjusting member of the invention of claim 6, claim 7
The invention may include means for setting the opening time.

In the image forming apparatus of the invention of claim 8, V*Ft*((N-1)+(N-1)/NMAX)=(
A means is provided for finely adjusting Ft or V so as to satisfy the relational expression N-1)*L.

[0026] The image forming apparatus according to the invention according to claim 8 is provided with means for changing the reading interval in the sub-scanning direction of the document reading device by a variable amount of Ft or V. There is.

In the image forming apparatus according to the tenth aspect of the invention, in the image forming apparatus according to the first aspect, means for collectively arranging colors having the lowest transmittance in a portion where the amount of light reaching from the light source is greatest. It is equipped with

[0028]

In the invention having the above structure, the light emitted from the light source reaches the photosensitive recording medium via the optical shutter and exposes it. At this time, the image appearing on the optical shutter and the photosensitive recording medium move synchronously. Furthermore, this optical shutter is divided into three colors, so that three colors are exposed simultaneously in one exposure.

Particularly, in the image forming apparatus according to claims 2 to 4, the light shutters separated into red, green, and blue (spare) (n pieces) each control the light emitted from the light source, and control the light emitted from the light source, and The moving speed of the optical shutter and the information moving speed of the optical shutter are synchronized to expose the photosensitive recording medium.

Furthermore, in the image forming apparatus according to the fifth to seventh aspects of the invention, the amplitude of the drive signal for each line of the optical shutter is set for each line, and the light transmittance of each line is adjusted using a light amount adjusting member. The photosensitive recording medium is exposed to light by changing it line by line or by changing the shutter open time of each line of the optical shutter line by line.

It is also possible to expose a photosensitive recording medium by combining the inventions of claims 5 to 7.

Furthermore, when the input is a digital signal based on a binary code, when the inventions of claims 5 to 7 are combined, the amount of light transmission for each line is 2 to the m power (
It is also easy to configure the optical shutter so that m is a positive integer.

In the image forming apparatus according to the eighth aspect of the invention, V*
Ft*((N-1)+(N-1)/NMAX)=(N-
1) Finely adjust Ft or V so that the relational expression *L is satisfied, and expose the photosensitive recording medium.

In the image forming apparatus according to the ninth aspect of the invention, Ft
Alternatively, depending on the variable amount of V, the reading interval in the sub-scanning direction of the document reading device changes.

In the image forming apparatus according to the tenth aspect of the invention, 3
Among the light shutters separated into primary colors, the color with the lowest transmittance is collectively arranged in the area where the amount of light arriving from the light source is greatest.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 5 is a schematic diagram of a photosensitive pressure sensitive printer using a liquid crystal shutter for exposure control, which is common to all embodiments described later.

As shown in FIG. 5, the photosensitive pressure sensitive printer 101 uses photosensitive paper consisting of a photosensitive pressure sensitive paper 12 (hereinafter referred to as microcapsule paper) and a color developing paper 28 (hereinafter referred to as recording paper). .

A halogen lamp 53, a condensing reflector 53a, and a condensing lens 53b are arranged above the printer 101, and a reflecting mirror 8 is disposed to the left of the condensing lens 53b. The light emitted from the halogen lamp 53 is condensed by the reflector 53a and the condensing lens 53b, and is emitted toward the reflecting mirror 8 as substantially parallel light.

Below the reflecting mirror 8, an active matrix type liquid crystal shutter 37 and an exposure stage 11 are held in parallel with each other at a small distance.

Furthermore, the microcapsule paper 12 is structured to pass between the liquid crystal shutter 37 and the exposure table 11. Therefore, the light reflected downward by the reflecting mirror 8 is projected onto the liquid crystal shutter 37.
By opening and closing 7, a latent image is formed on the microcapsule paper 12. A detailed explanation of this liquid crystal shutter 37 will be given later in accordance with the invention of each claim. However, the configuration of the liquid crystal shutter used here is the configuration shown in FIG. It is divided into four types, each with 64 lines.

On the other hand, a cartridge 15 is arranged in the center of the printer 101, and the long microcapsule paper 12 is stored in the cartridge 15, which is removable from the machine while being wound around the cartridge shaft 14. There is.

With the cartridge 15 set at a predetermined position within the machine, the leading end of the microcapsule paper 12 is pulled out toward the exposure table 11. A feed roller 19 and a dancer roller 21 for tension adjustment are disposed on the lower left side of the exposure table 11.

On the right side of the dancer roller 21, a pressure developing device 22 including a large diameter roller 22a and a backup roller 22b is disposed.
On the right side, there is a separation roller 23 for separating the microcapsule paper 12 and color developer paper 28 that are in close contact with each other as described later.
is arranged, and the separating roller 23 and the cartridge 1
A winding shaft 24 for fitting and holding the microcapsule paper 12 is disposed between the microcapsule paper 12 and the microcapsule paper 12. Cartridge 15
The microcapsule paper 12 that has come out from the top is guided by a feed roller 19, passes above the exposure table 11, passes through a dancer roller 21, a pressure developing device 22, and is further guided to a separation roller 23. It is wound up on the winding shaft 24. Note that the unexposed microcapsule paper 12 after leaving the cartridge 15 is maintained in an unexposed state by the light shielding cover. A paper feed cassette 29 containing developer paper 28 is installed below the pressure developing device 22 . Above the paper feed cassette 29, a suction cup-type paper feed mechanism 30 that sucks paper using negative pressure suction is arranged, and the developing paper 28 is taken out one by one by the paper feed mechanism 30.

A feed guide 31d, feed rollers 31a, 31b, 3 are provided between the paper feed mechanism 30 and the pressure developing device 22.
1c is arranged, and the color developing paper 28 is fed by a feed roller 31a.
, 31b, 31c, and a feed guide 31d, and are carried into the pressure developing device 22.

A heat fixing device 32 is disposed to the right of the pressure developing device 22, and a paper discharge tray 33 for storing the developer paper 28 on which an image is formed is disposed to the right of the heat fixing device 32. It is set up.

Furthermore, this printer has an autoloading function for automatically setting the microcapsule paper 12 on a predetermined transport path within the apparatus. This is a function that automatically pulls out the leader film attached to the tip of the microcapsule paper 12 into the apparatus, transports it within the apparatus, and winds it around the winding shaft 24. As a result, the microcapsule paper 12 following the leader film section is also wound up on the winding shaft 24, and the setting in the apparatus is completed.

For this automatic loading, a half-moon roller 17 is provided between the feed roller 19 and the cartridge 15 for pulling out the leader film section, and a separation chute 27 is provided for guiding it to the take-up shaft 24. It is rotatably mounted. An upper winding guide 25 is disposed around the winding shaft 24 for winding the leader film.

Next, the operation of this printer will be explained.

When the cartridge 15 is set in the printer 101, autoloading starts.

[0050] The half-moon roller 17 rotates once to several times in the conveying direction only at the start of auto-loading, and feeds the leader film portion to the roller 20. Then it stops and
Subsequent conveyance is performed by driving the rollers 20.

The upper winding guide 25 and the separation chute 27 are
The microcapsule paper 12 is rotated to the position shown by the one-dot chain line.
When the autoloading of the leader film attached to the tip of the winding shaft 24 is completed,
The upper take-up guide 25 and the separation chute 27 return to the positions indicated by solid lines, allowing output.

[0052] When RGB data of an output image is sent to a printer input unit (not shown), the printer 101 starts forming an image. That is, based on the input data, the liquid crystal shutter 37 is opened and closed as needed, and the data movement speed on the liquid crystal shutter is synchronized with the microcapsule paper 12 to perform overlapping exposure of each color, and the microcapsule paper 12 is exposed. form an image. Note that the method for processing input data will be explained in detail later.

Microcapsule paper 12 on which a latent image is formed
is conveyed, and the uppermost developing paper 28 of the paper feed cassette 29 is conveyed by the paper feed mechanism 30, feed rollers 31a, 31b, 31c, etc.

The microcapsule paper 12 and the color developer paper 28 are supplied to the pressure developing device 22 in a state where they are in close contact with each other and are integrated, and the microcapsule surface on which the latent image of the microcapsule paper 12 is formed and the color developer paper 28 are separated. The color developer coated surface is integrally sandwiched between the large diameter roller 22a and the backup roller 22b in a state in which they are in contact with each other on the inside, and pressure is applied. This pressure destroys the unexposed microcapsule paper and forms an image on the developer paper 28.

The microcapsule paper 12 and the color developer paper 28 that have come out of the pressure developing device 22 are separated by the separation roller 23, and then the color developer paper 28 is transferred to the heat roller 3 of the heat fixing device 32.
After color development is promoted by the paper sheet 2a and an image is formed, the paper sheet is conveyed to a paper discharge tray 33 by a paper discharge roller 32b. still,
The separated microcapsule paper 12 is passed through a separation roller 23 and wound onto a winding shaft 24. Note that a color copying machine can be easily constructed by combining the above-mentioned printer and color scanner.

FIG. 6 shows an example of a hardware configuration for driving the liquid crystal shutter 37 based on input RGB data. A memory control circuit (using a central processing unit (CPU)) 67 includes a read-only memory (ROM) 68 in which programs and data are stored, and a random access memory (RAM) 73 for data processing.
and a timing generation circuit that generates various timings (
69 (using a cathode ray tube controller (CRTC)) and a video RAM (using dual port RAM) 72 for storing liquid crystal output images. Furthermore, the CPU 67 stores data buffer 6 for three colors of RGB.
6, and the input data is corrected by a correction circuit 65 and then transferred to a buffer 66. buffer 6
6 is composed of a red buffer 66R, a green buffer 66G, and a blue buffer 66B, each of which has a buffer amount of R.
BUF, GBUF (=RBUF+64 lines), BBU
F (= RBUF + 128 lines), WBUF (= RBU
F+192 line, used when implementing the invention of claim 3)
It becomes.

The output data of the VRAM 72 is compared with the output value of the counter 71 by the digital comparator 70, and the output of the digital comparator 70 is sent to the liquid crystal shutter 37 together with various synchronization signals generated by the timing control circuit 69. .

The input data is transferred to the correction circuit 65 as digital data of 8 bits each for RGB using output data from a computer or a scanner. Correction circuit 6
In step 5, conversion processing such as enlargement/reduction and partial color conversion is performed, and furthermore, gamma characteristics of the microcapsule paper 12 are corrected, smoothing processing, etc. are performed. When the correction process is completed, the data is sent to the buffer 66 separately for RGB and waits until the data is read out by the CPU 67. The buffer amount of the buffer 66 is 64 lines for each color of the liquid crystal shutter, and the microcapsule paper 12 is sequentially exposed to red, green, and blue.
According to the exposure order, the buffer amount for patina is 64 and
I have an extra 128 lines. This buffer also has the role of correcting the difference between the liquid crystal data display speed and the input data speed.

[Embodiment 1] Hereinafter, an embodiment of a liquid crystal shutter 37 embodying the invention of claim 1 will be described with reference to the drawings.

FIG. 1 is a schematic diagram of an active matrix type liquid crystal shutter 37 used in the present invention. In the figure, the X direction (main scanning direction) is a direction perpendicular to the conveyance direction of the photosensitive recording medium, and the Y direction (sub-scanning direction) is the conveyance direction of the photosensitive recording medium (hereinafter referred to as the X direction and Y direction). A color filter is deposited on each opening 60 of the liquid crystal shutter, and the wavelengths transmitted through each opening 60 are selected.

In the liquid crystal shutter, the Y direction is 3
It consists of n lines: red (R) color filters are n lines from R1 to Rn, green (G) color filters are n lines from G1 to Gn, and blue (B) color filters are from B1. It consists of n lines up to Bn.

FIG. 2 is an enlarged view of a part of the liquid crystal shutter 37. Each opening 60 is connected to a switching element 61, and by driving the switching element 61, the opening 60 is opened. Light transmittance changes. Figure 2 (
When the cells are arranged in a staggered manner as in a), the two rows correspond to one line in FIG. 1. In other words, Y1A and Y
Two terminals of 1B are used to expose one line of the output image once. Using this arrangement, the resolution of the output image can be increased relatively easily.

FIG. 2(b) is another example of a partially enlarged view of the liquid crystal shutter 37, in which the openings are arranged without gaps in the X direction, and the locations where the switching elements 61 are arranged are arranged in the Y direction. It is arranged between the openings. When forming images while moving the photosensitive recording medium,
As shown in FIG. 2(b), the length of the opening in the Y direction can be shortened.

On the other hand, if each opening of the liquid crystal shutter shown in FIG. , a color image is recorded as a latent image on a photosensitive recording medium. In other words,
Both RGB are exposed n times, and by opening and closing the liquid crystal shutter based on each gradation data, a color image with n gradations of each color can be formed.

[Embodiment 2] Next, an embodiment of the invention of claim 2 will be described. In addition to the required number n for each RGB part of the liquid crystal shutter in Figure 1, the liquid crystal shutter in Figure 3 has a
The configuration includes a line spare shutter.

Next, a method of using this preliminary shutter will be explained based on FIG. 16. When manufacturing liquid crystal shutters, yield is a major issue for high-pixel, high-definition shutters. For example, in the case of a TFT type, a short circuit between a gate and a drain causes a line defect, and a short circuit between a gate and a source or a short circuit between a drain and a source causes a point defect. However, if it is not used as a display but as a liquid crystal shutter, and scanning exposure is used instead of static exposure, even if line defects or point defects occur, it may be possible to do so without affecting the image quality.

For example, in FIG. 3 described above, if there is a single line defect or a point defect, it can be corrected. In FIG. 3, when a line defect occurs on the R3 line, one line of the spare shutter section (A) can be used in place of the defective line. If this configuration is used, it may be a bit complicated in terms of hardware, such as using registers to select which lines to use from among all the lines, including the spare line, but it is possible to use high-pixel, high-definition Considering the poor yield of shutters, this method can be said to be quite effective. Further, in the case of a point defect of about one opening, in the case of scanning exposure of multiple lines, since it hardly affects the image quality, it is possible to use the device with the defect.

Furthermore, even if the backup line is not used, correction can be made to some extent. FIG. 16 shows this situation. Here, it is also assumed that, with the hardware configuration shown in FIG. 6, liquid crystal data for gradation expression is created by comparing the counter output and the VRAM output as shown in FIG. Fig. 16 shows the case where there is a line defect in the second line of the R shutter section.
The processing executed when the PU 67 transfers data to the VRAM 72 is shown. The second line is always open when the input data value (density) is 4 or more, so first input R data (S41), determine whether the value is 4 or more (S42), and check if the value is less than 4. In this case (S42: NO), the input data is used as is. If R data is 4 or more (S42
: YES) and compare whether the R data is 251 or less (S
43), if the R data is greater than 251 (S43:N
O), use the input data as is. R data is 25
If it is less than or equal to 1 (S43: YES), 4 is added to the input data and used (S44). In this method, no correction is made when the input data density is high (greater than 251), but since it is a high density area, it hardly affects the image.

[Embodiment 3] Further, as shown in FIG. 4, the spare part (A) line is arranged without a color filter, thereby obtaining an embodiment of the invention of claim 3. The configuration of the liquid crystal shutter used here is shown in Figure 4, and is divided into four types: red (R), green (G), blue (B), and white (W: no color filter). , each with 64 lines. Further, instead of W, a filter other than RGB, such as a yellow filter, may be used. How to use these second and third reserve lines will be explained in detail later.

Next, in the above image forming process,
An example of a method for processing input data will be described using FIG. 6. For simplicity, it is assumed that a digital video input liquid crystal panel is used as the liquid crystal shutter 37, and that the liquid crystal shutter controller and driver are included in the liquid crystal shutter 37.

The CPU 67 sequentially reads data from the buffer 66 and writes the display data to the liquid crystal display VRAM 72, and causes the timing generation circuit 69 to write the display data to the VRAM 72 in each of the four divided areas of the liquid crystal shutter.
Set the start address. The above settings are performed by causing the timing generation circuit 69 to generate an interrupt to the CPU 67.

This situation is shown in FIGS. 7 to 10. FIG. 7 shows the address structure of the VRAM 72, which is divided into four areas of RGBW. 8 to 10 show flowcharts for changing liquid crystal shutter display data only for the red (R) region for simplicity, and the processing is the same for each of the green, blue, and white regions.

FIG. 8 shows the main processing, in which the start address of the VRAM 72 in the red (R) area of the liquid crystal shutter is RAD, and the data rewriting address of the VRAM 72 is RWR. FIG. 9 shows data transfer processing (S06)
2 is a flowchart of a subroutine. FIG. 10 shows interrupt processing that occurs in synchronization with the vertical synchronization signal, and T
RFLG is a flag indicating that an interrupt has occurred.

First, the initial value (00h) is set in the VRAM 72, and the start address (RAD=RSTART) of each area of the liquid crystal shutter and the VRAM rewrite address (RWR=RSTART) are input to the timing generation circuit 69.
(S01) and wait for the start of image formation (S0
2). When image formation starts (S02: YES), 128 lines of data are read from the buffer 66, and V
Write to the R area of the RAM 72 (S03). At that time, G
Addresses for the first 64 lines of the area and the first 12 lines of the B area
0h (shutter fully closed) is entered in the address for 8 lines. Then, unmask the hard interrupts (S04
) and monitor that TRFLAG is inverted (S05)
. When TRFLAG is inverted (S05: YES), data transfer processing (S06) is performed, and when image formation is completed (S07: YES), the operation is completed and the process returns to S01, and image formation is not yet completed. case (S07:N
O), return to S05, and continue from S05 to S0 until the end of image formation.
Repeat step 7. The inversion of TRFLAG is performed every time a hard interrupt occurs, as shown in Figure 10 (
S10).

It is assumed that the hard interrupt is generated based on the relationship between the generation timing of the vertical synchronization signal and the vertical (frame) period (EMAX) required to expose one pixel. This vertical synchronization signal is generated during a blank period when the liquid crystal shutter 37 is time-divisionally driven in the Y direction. Therefore, if two frame times are required to expose one pixel, one hard interrupt will occur out of two vertical synchronization signals.

In the data transfer process (S06), the process shown in FIG. 9 is performed. First, the start address RAD is RE
It is determined whether ND has been reached (S21), and RAD=
In the case of REND (S21: YES), RST is sent to RAD.
ART is set (S22), and if RAD<REND (S21: NO), an address added by one line is set to RAD (S23). Its setting address RAD
By setting in the timing generation circuit 69 (S24)
, the data on the liquid crystal shutter is shifted by one line in the microcapsule paper conveyance direction. After that, buffer 66R
1 line of display data is read from (S25), P
Data is transferred to the one line area indicated by the WR address (S26). Next, the PWR address is REND+
Determine whether the 63rd line has been reached (S27), and
If WR=REND+63 (S27: YES), PW
R is set to RSTART (S28), and PWR<RE
In the case of ND+63 (S27: NO), the PWR address is added by one line (S29). Above S21 to S2
The process shown in 9 is completed in a time shorter than the hard interrupt interval. Setting of the start address in S24 is performed during the vertical blanking period of the liquid crystal shutter 37.

Next, the VR output by the above processing
A description will be given of how the output data of the AM 72 is processed into data suitable for the liquid crystal shutter 37 and expressing gradation. Through the above processing, 8-bit data is sequentially output from the VRAM 72, but it is necessary to convert this data into 1-bit liquid crystal display data based on this data. Therefore, the state of data conversion will be explained using FIG. 11. Here, each color has 256 lines on a liquid crystal with 64 lines for each color.
In order to express gradation, four frames are used to expose one pixel.

[0078] The output data of VRAM72 is transferred to PDATA,
It is assumed that the comparison data of the counter 71 is QDATA, and one pixel is exposed using four frames while moving the data in the transfer direction of the microcapsule paper. In other words, PDA
It is assumed that the first line of TA expresses densities 1 to 4, and the second line expresses densities 5 to 8.

In this case, the first frame is P of the first line.
Compare DATA and QDATA (value 0) and find that P>Q
The output is input data to the liquid crystal shutter 37. This means that when P>Q, the shutter at that position is opened. In the second frame, PDATA of the first line is compared with QDATA (value 1), and the output of P>Q is used. Furthermore, the third frame is PDATA and QDATA (
Compare with value 2). Moving further to the second line, the first frame is compared with PDATA and QDATA (value 4). On the nth line, the first frame is PDATA and Q.
DATA (value (n-1) * 4), 2nd frame is PDA
The values to be compared will be successively increased, such as TA and QDATA (value (n-1)*4+1). That is, if the comparison data QDATA of the comparator 70 is counted up by the counter 71, 256 gradations for each color can be realized. As the simplest example, it is possible to use a liquid crystal shutter with 256 lines for each color.

Note that in the above embodiment, the buffer 6
The process of transferring data from 6 to VRAM 72 is performed by the CPU.
The processing may be performed only by hardware without using 67 (without software intervention).

[Embodiment 4] Next, as an embodiment of the invention according to claim 3, an example in which a preliminary shutter is used as a sub-exposure shutter will be described with reference to FIGS. 4 and 6. When the microcapsule paper 12 is irradiated with a small amount of white light over the entire latent image recording area, the gradation of the output image can be improved. However, the black density tends to be low, and especially when the image includes both text and photographs, the sub-exposure tends to make the black text lighter. Therefore, a method of irradiating white light onto areas other than the black area using the preliminary shutter section shown in FIG. 4 can be considered. A flowchart of the process is shown in FIG. 12(a). This process is performed by the color correction circuit 65 shown in FIG.
7 as sub-exposure data.

First, each pixel of RGB data is read (S31), and it is determined whether the values of all RGB data are 30 or less (S32). If both RGB are 30 or less (
S32: YES), the pixel is determined to be black, and W (white: sub-exposure amount) data is set to 10 (S33). N at S32
In the case of O, as a pixel that performs sub-exposure to improve gradation,
The W data is set to 10 (S34). The value of the W data is determined at any time, such as 10 if it is desired to irradiate 10 lines with white light. Then, it is determined whether all the data has been processed (S35), and if there is still processing data (S35: NO), the process returns to S31, and the following S3
Repeat steps 1 to S35. The above-described effects can be achieved by performing all processing using software, using only the RGB regions, and not using white light. However, if white light can be applied using hardware, software processing can be reduced and it can also be used for other purposes. An example is shown below.

Since microcapsule paper is difficult to express white (pure white) (uncured capsules remain), it is possible to use the preliminary shutter for processing to further emphasize the white level. This case is shown in FIG. 12(b), and R
Determine if both GB are 220 or higher (S36), 2
If it is 20 or more (S36: YES), 25 is added to the W data.
5 (S37), and if it is not 220 or more (S36
:NO), if the W data is set to 0 (S38), the microcapsules can be completely cured by the preliminary shutter.

[Embodiment 5] Next, an embodiment embodying the invention of claim 5 will be described based on FIGS. 13 and 14.

FIG. 13(a) is a schematic diagram of driving a matrix-structured liquid crystal shutter when the conveyance direction of microcapsule paper is Y. Several types of driving voltages (V1- V6), a voltage generation circuit 82, an X direction driver 80, and a Y direction driver 81.
It is composed of The liquid crystal shutter is time-divisionally driven (dynamically driven) in both the X and Y directions, and for the sake of simplicity, we will focus only on the drive in the Y direction.

FIG. 13(b) is an example of an input voltage waveform in the Y direction, and as shown in the figure, an AC time-division waveform is input. Figure 1
3(c) is the input waveform to the next line in FIG. 13(b).

In this case, if there is a voltage amplitude up to V1 or V2, that line is selected, and X
Each opening of the liquid crystal opens and closes based on the difference in direction from the input waveform.

Here, the Y-direction input voltage is set to the first line YV.
0 (V1-V6), 2nd line YV1 (V1'-V6'
), if the value of YV1 is set lower than the value of YV0, the transmittance of the openings on the first line and the second line will change even if the same X input is applied. This is because the transmittance of the liquid crystal depends on changes in the liquid crystal drive voltage, and by changing the drive voltage in the Y direction for each line, the transmittance when the aperture is open for each line can be changed. can be changed.

[Embodiment 6] In the above example, if the liquid crystal drive voltage YV is set so that the transmittance varies by 2 to the m power (m: a positive number) for each line, the result will be as shown in FIG. 14(a). A driving voltage-transmittance (relative value) relationship as shown can be obtained.

FIG. 14(b) is a configuration diagram of the red (R) portion of the exposure liquid crystal shutter when the above-mentioned driving voltage is applied to each line. Change the drive voltage from YV0 to YV3
The transmittance at that time was changed to 1, 1/2,
If it is 1/4 and 1/8, there are 31 lines with transmittance 1, and 1 line each with transmittance 1/2, 1/4, and 1/8.
If it is configured to have lines, 256 gradations can be expressed with a total of 34 lines. Furthermore, since each line can be made to correspond to a certain bit of input data, the hardware configuration can also be simplified.

[Embodiment 7] Next, an embodiment embodying the invention of claim 6 will be described based on FIG. 15. Figure 15 (
a) uses a light amount adjustment member to adjust the transmittance for each line to 1
The figure shows two types: 1/16 and 1/16. Here, too, the transmittance is changed to the m power of 2 (m: positive number).

Here, the drive voltage for each line mentioned above is set to YV.
FIG. 15(b) shows the configuration of a liquid crystal shutter when using both the method of changing four types of light intensity adjustment filters 88 from 0 to YV3 and the method of changing two types of light amount adjustment filters 88, F0 and F1. In other words, 256 gradations can be expressed with an 8-line shutter, and the signal for opening and closing each line in this case corresponds to each bit of 8-bit input data.

Furthermore, instead of using the light amount adjustment member, a liquid crystal shutter may be used in which the aperture ratio of the shutter, that is, the area of the pixel when the pixel of the liquid crystal shutter is in a light transmitting state is changed for each line. This configuration can be achieved by changing the shape of the transparent electrode constituting the liquid crystal shutter in accordance with the aperture ratio. In addition, a mask plate on which transparent windows are formed according to the aperture ratio described above is closely attached to an ordinary liquid crystal shutter having transparent electrodes of the same shape, with each transparent window aligned with each pixel of the liquid crystal shutter. Good too.

[Embodiment 8] As a specific embodiment of the invention of claim 7, the liquid crystal shutter is configured using PWM (pulse width modulation).
When driving or performing frame modulation, the opening/closing ratio may be set for each line. For example, the first line may be set to be open for the entire period of one frame in response to the shutter open signal, while the second line may be set to be open for only 1/2 frame time.

[Example 9] Next, claims 8 to 9
An embodiment embodying the invention will be described based on FIG. 17. When the liquid crystal shutter of FIG. 1 is time-divisionally driven in the Y direction with a frame period Ft, the line interval is L, the transport speed of the microcapsule paper 12 is V, and the number of liquid crystal shutter lines is NMAX.

FIG. 17(a) shows the case of static drive, where the data rewriting time is Ft', the exposure area for the first line of microcapsule paper 12 is P01, and the exposure area for the Nth line is P0N. The time from exposing P0N to starting P0N exposure is Ft'*(N-1),
It can be easily inferred that the microcapsule paper only needs to move by (N-1)*L during this time. In other words, Ft'*(
It is sufficient to satisfy N-1)*V=(N-1)*L.

[0097] Exactly the same idea can be applied to the frame period F.
FIG. 17B shows the relationship between the exposure positions of each line when dynamic driving of t is applied. As shown in the figure, since the data rewriting time is slightly different between the first line and the Nth line, dot misalignment occurs in the output. This dot misalignment is Ft*(N-
1)/NMAX This occurs due to a time lag, and the exposure timing is corrected to correct this lag time, as shown in FIG. 17(c). In other words, on the Nth line, F
When t*(N-1)/NMAX time has passed, the amount of movement becomes (N-1)*L. Expressed in the formula,
V*Ft*((N-1)+(N-1)/NMAX)=(
N-1)*L (Formula 1). In fact, in most liquid crystal shutters, the line spacing is constant, and when dynamically driven, even if there is a blank period (time when data is not rewritten), the period is compared to the data rewriting time. Therefore, equation 1 can be applied to exposure by all lines of the liquid crystal shutter. For example, it can be applied to a liquid crystal panel for digital video input, such as the liquid crystal shutter 37 shown in FIG.

The conclusion is that if formula 1 is satisfied, dot misalignment will not occur even if overlapping exposure is performed using a plurality of lines. In other words, as shown in the invention of claim 8, it is sufficient to determine the interval L so as to satisfy Expression 1.

The above formula can also be applied to cases where several frames are required to expose one pixel; however, when M frames are required, the formula is as follows.

V*Ft*((N-1)*M+(N-1)/NMAX)
=(N-1)*L Among the components of Equation 1, the microcapsule paper conveyance speed V may be difficult to keep constant when driven by a roller, for example, because the accuracy of the roller diameter etc. varies. many. In other words, it is conceivable that dot misalignment may or may not occur between machines. Therefore, as shown in an eighth aspect of the invention, adjustment is made possible by providing a mechanism for finely adjusting the microcapsule paper conveyance speed V and the frame period Ft.

For example, in FIG. 6, the timing control 69
When using a CRT controller as a controller, this can be achieved by rewriting the value of its vertical synchronization time fine adjustment register. Further, when the microcapsule paper 12 is transported by a step motor, the pulse rate thereof may be changed.

When applying the above method to a color copying machine, if the reading interval of the input scanner in the sub-scanning direction is constant, fine adjustment of Ft and V will slightly change the magnification of the microcapsule paper 12 in the Y direction. There is a possibility of going crazy. Therefore, when Ft or V is changed as shown in the ninth aspect of the invention, the reading interval in the sub-scanning direction of the input device may be changed accordingly. This may change the input device motor speed or feed step. Of course, when Ft or V is changed, changes may be automatically made to correct it.

[Embodiment 10] Finally, an embodiment embodying the invention of claim 10 will be briefly described. In the printer of FIG. 5, a halogen lamp 53, a reflector 53a,
The light generated by the condensing lens 53b is irradiated onto the liquid crystal shutter 37, but due to its structure, there is a tendency for the amount of light to fall off at the edges, and the amount of light at the center tends to be high. In addition, as shown in Figure 1, the liquid crystal shutter has red, blue,
When a three-color separation filter of green (yellow, magenta, and cyan can also be configured) is attached, the light transmittance of the color filter also differs depending on the type of color filter. In FIG. 1, the transmittance of the green (G) filter is lower than that of the red and blue filters. Therefore, as shown in FIG. 1, the G filter is placed in the center where the amount of light is relatively high. This arrangement makes it possible to improve the efficiency of the entire device. In addition, when horizontal light is bent vertically using a waveguide to enter the liquid crystal, the amount of light is lowest at the center, so it is recommended to place an R filter at the center and a G filter at the periphery. can also be considered.

[0104]

[Effect of the invention] As is clear from the detailed description above,
According to the present invention, overlapping exposure can be performed on a photosensitive recording medium capable of expressing halftones by controlling the light emitted from the light source using shutters for red, green, and blue, each consisting of a plurality of lines. , it is possible to configure a high-speed, high-resolution image forming apparatus. Furthermore, since a spare shutter can be provided, the spare shutter can be used as a means of producing images with higher reproducibility, and it also provides a means of correcting defects in the shutter, making it possible to reproduce images at low cost. A high quality image forming apparatus can be configured.

[0105] Furthermore, the light transmittance can be adjusted for each line by setting the amplitude of the shutter drive signal independently for each line, and by changing the shutter open time for each line using a light amount adjustment member. , high gradation can be achieved with a shutter with fewer lines. This also contributes to miniaturization and cost reduction of the device. Furthermore, the light transmittance for each line is increased by 2.
By setting it to the m power (m: positive number), the data processing process can be simplified. This contributes to cost reduction and data processing errors.

[0106] Furthermore, when an optical shutter composed of a plurality of lines is dynamically driven in the transport direction of the photosensitive recording medium with a frame period Ft, the line spacing L,
When the transport speed of the photosensitive recording medium is V, the exposure of the Nth line is V*Ft*((N-1)+(N-1)/NMAX)=(
Line spacing L to satisfy the relational expression N-1)*L
, and finely adjust Ft and V, it is possible to obtain an output image without positional deviation between dots.

Furthermore, among the red, green, and blue light shutters, the color with the lowest transmittance can be collectively placed in the area where the amount of light reaching from the light source is greatest, so the efficiency of the entire device can be improved. Can be done.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a liquid crystal shutter.

FIG. 2 is a partially enlarged view of a liquid crystal shutter.

FIG. 3 is a schematic configuration diagram of a liquid crystal shutter including a preliminary shutter.

FIG. 4 is a schematic configuration diagram of a liquid crystal shutter including a preliminary shutter.

FIG. 5 is a schematic configuration diagram of a scanning exposure type photosensitive pressure sensitive printer.

FIG. 6 is a configuration diagram of photosensitive pressure sensitive printer data processing.

FIG. 7 is an address configuration diagram of VRAM.

FIG. 8 is a diagram showing a flowchart of photosensitive pressure sensitive printer data processing.

FIG. 9 is a diagram showing a flowchart of photosensitive pressure sensitive printer data processing.

FIG. 10 is a diagram showing a flowchart of photosensitive pressure sensitive printer data processing.

FIG. 11 is a VRAM data comparison table.

FIG. 12 is a diagram showing a flowchart of preliminary shutter processing.

FIG. 13 is an explanatory diagram of a liquid crystal shutter drive circuit.

FIG. 14 is a shutter configuration diagram when the drive voltage of the liquid crystal shutter is changed.

FIG. 15 is a configuration diagram of a shutter when a light amount adjusting member is used.

FIG. 16 is a flowchart showing a defective shutter correction method.

FIG. 17 is a diagram showing a method for correcting dot misalignment of a liquid crystal shutter.

FIG. 18 is a schematic configuration diagram of a conventional analog photosensitive pressure-sensitive copying machine.

FIG. 19 is a schematic configuration diagram of a conventional static exposure full color printer.

[Explanation of symbols]

37 Liquid crystal shutter 101 Photosensitive pressure sensitive printer 82 Voltage generation circuit 88 Light amount adjustment filter

Claims (10)

[Claims] 1. A light source that irradiates a moving photosensitive recording medium with light necessary for exposing the photosensitive recording medium, and image information that is displayed, and that emits light from the light source in accordance with the displayed image information. In the image forming apparatus, the image forming apparatus is provided with a light shutter that blocks light and performs exposure by synchronizing the moving speed of the photosensitive recording medium and the moving speed of image information displayed on the optical shutter, wherein the optical shutter is An image forming apparatus characterized in that the image forming apparatus is separated into three primary colors in the direction of movement, each of which is composed of n lines (n>1) of shutters. 2. The image forming apparatus according to claim 1, further comprising a spare optical shutter for each color optical shutter. 3. The image forming apparatus according to claim 1, further comprising an optical shutter having a transmission wavelength band different from the transmission wavelength of the optical shutter of each color. 4. The image forming apparatus according to claim 1, wherein the photosensitive recording medium is exposed to light n times for each of the three primary colors to achieve gradation expression of at least n gradations for each color. image forming apparatus. 5. The image forming apparatus according to claim 1, wherein the amplitude of the drive signal for each of the n lines can be set independently for each line. 6. The image forming apparatus according to claim 1, wherein the light transmittance of each of the n lines is changed line by line using a light amount adjusting member. 7. The image forming apparatus according to claim 1, wherein the shutter open time of each of the n lines is independently changed for each line. 8. The image forming apparatus according to claim 1, wherein when the optical shutter is composed of NMAX lines and is dynamically driven with a frame period Ft, the line interval L
, the conveyance speed of the photosensitive recording medium is V, then the exposure of the Nth line is V*Ft*((N-1)+(N-1)/NMAX)=(
An image forming apparatus characterized in that Ft or V can be finely adjusted so as to satisfy the relational expression N-1)*L. 9. The image forming apparatus according to claim 8, wherein the reading interval in the sub-scanning direction of the document reading device is changed by a variable amount of Ft or V. 10. In the image forming apparatus according to claim 1, the optical shutter is separated into three primary colors, and the color with the lowest transmittance is collectively arranged in the area where the amount of light reaching from the light source is greatest. An image forming apparatus characterized by: