JP2002278201A - Device and method for laser output control of wet type electrophotographic printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser output controller for a wet type electrophotographic printer and its control method which can obtain a sharp image by controlling laser power according to conditions such as a case wherein colors are superposed each other at a drawing position and a case wherein the colors are not superposed. SOLUTION: The laser output controller for the wet type electrophotographic printer equipped with a photosensitive drum, an electrifying means, an exposure means, etc., is equipped with a laser output value data storage part 55 which stores laser output values of respective colors by combinations of colors, a color combination data storage part 54 which stores drawing data as combination data of colors by pixels, and a laser controller 51 which selects a corresponding color from the color combination data of the respective pixels, selects the color from pixels in the laser output value data storage part 55, and selects the laser output value corresponding to the color. Consequently, the laser power can be varied corresponding to the change of the conditions and a sharp image can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser for a wet electrophotographic printing machine for developing an electrostatic latent image formed on the surface of a photosensitive drum with a liquid toner and transferring the developed image onto printing paper. The present invention relates to an output control device and a control method thereof.

[0002]

2. Description of the Related Art Conventionally, for example, Y (yellow), M (magenta), C
A plurality of colors such as (cyan) and K (black) are sequentially superimposed to perform drawing, and an image based on an image formed by sequentially combining multicolor liquid toners is transferred via a transfer roller. 2. Description of the Related Art A wet electrophotographic printing machine that transfers images onto printing paper disposed between the transfer roller and a backup roller is known. The printing machine includes a charging unit that charges a photosensitive drum surface having photosensitivity, an exposure unit that exposes and scans the photosensitive drum based on drawing data to perform drawing to form an electrostatic latent image, and a photoconductor. Developing means for developing an electrostatic latent image on the drum, the developing means including a plurality of developing rollers for sequentially supplying multicolor liquid toner to the photosensitive drum.

On the other hand, the exposing means comprises, for example, a laser light source, a polygon scanner, etc., and the laser output from the laser light source is reflected after being incident on a polygon scanner rotating at a constant speed, and fθ Drawing is performed by scanning the photosensitive drum through a lens.

[0004]

By the way, when an image is formed on a photosensitive drum by image-on-image, the charged potential on the photosensitive drum is compared with the potential (electrostatic latent) of a portion exposed by laser. When the image (image) falls below the developing roller potential, toner migration (electrophoresis) occurs and development is performed. For example, at the time of drawing the first color, a laser exposure potential determined by the sensitivity characteristic with respect to the laser wavelength is obtained on the photosensitive drum. However, at the time of drawing the second color, a laser exposure potential determined by the sensitivity characteristic with respect to the laser wavelength on the photosensitive drum is obtained for a portion not exposed by the first color. Since the first color toner is present in the area exposed by, if the laser output power is output without adjustment, the laser energy is absorbed or reflected by the toner, and the desired laser exposure potential cannot be obtained. There is a risk. As a result, a clear image cannot be obtained, which causes a problem that print quality is deteriorated.

In order to adjust the laser output, laser output data for each color must be held, and the laser output data for each color must be determined based on the data. Here, if the resolution of the laser output is, for example, 256 gradations, 8-bit data is required for one dot (pixel). Therefore, when eight colors such as yellow are superimposed on one pixel, for example,
It must have 8 bits × 8 colors = 64 bits of data. Therefore, as the print image becomes larger and the resolution becomes larger, it is necessary to have a large storage device for holding the data of the laser output.

One object of the present invention is to control the laser power in accordance with conditions such as overlapping or non-overlapping of a color at a drawing position, and to obtain a laser output of a wet electrophotographic printing machine capable of obtaining a clear image. A control device and a control method thereof are provided.

Another object of the present invention is to provide a laser output control device of a wet type electrophotographic printing machine capable of reducing the capacity of a storage device for holding laser output data, and a control method therefor.

[0008]

According to a first aspect of the present invention, there is provided a photosensitive drum on which an image is formed on a surface thereof, charging means for charging the surface of the photosensitive drum, Laser output of a wet-type electrophotographic printing machine comprising: an exposure unit that irradiates a laser to form an electrostatic latent image; and a developing unit that develops the electrostatic latent image on the photosensitive drum by superimposing a plurality of colors. A control device, comprising: a laser output data storage unit in which laser output data for each color is stored for each of the plurality of color combinations; and a color combination data storage in which drawing data is stored as color combination data for each pixel. And a laser control unit for selecting the laser output data corresponding to the color to be drawn and controlling the laser. The laser control unit is configured to convert the color to be drawn into the color combination. And selecting a pixel incorporating a color to be drawn, selecting a pixel having the same color combination as the selected pixel from within the laser output data storage unit, Select the same color as the drawing color from inside,
A laser output control device for a wet electrophotographic printing machine, wherein laser output data corresponding to a selected color is used as laser output data of a color to be drawn.

In the present invention, the output value of the laser of the color to be drawn is determined by selecting the color to be drawn from the color combination data, selecting the pixel incorporating the color to be drawn, Pixels of the same color combination are selected from the laser output data storage unit, the same color as the color to be drawn is selected from the pixels in the laser output data storage unit, and laser output data corresponding to the color is selected.
Since the laser output value of the color to be drawn may be used, the laser power can be changed in accordance with a change in conditions, such as when the colors are superimposed or not, so that a clear image can be obtained. .

The laser output value of the color to be drawn may be determined by referring to the laser output data storage unit. The laser output data corresponds to the combination data of the colors in which the drawing data is formed for each pixel. So, for example,
Eight-bit data per pixel, which is required when the resolution of the laser output is 256 gradations, becomes unnecessary, and the capacity of the storage device that holds the laser output data can be reduced.

According to a second aspect of the present invention, there is provided a laser output control device for a wet electrophotographic printer according to the first aspect,
The plurality of colors include at least two colors. According to the present invention, multicolor printing can be performed, and it is possible to meet various demands of users.

According to a third aspect of the present invention, there is provided a photosensitive drum on which an image is formed on a surface thereof, a charging means for charging the surface of the photosensitive drum, and a laser beam irradiating the surface of the photosensitive drum for static electricity. A wet electrophotographic printing machine comprising: an exposure unit for forming an electrostatic latent image; and a developing unit for developing the electrostatic latent image on the photosensitive drum by superimposing a plurality of colors, and controlling the laser by a laser control unit. A laser output control method, wherein laser output data for each color is stored for each combination of the plurality of colors in a laser output data storage unit, and drawing data is stored in a color combination data storage unit for each pixel. The color to be stored and drawn is selected by the laser control unit from the color combination data in the color combination data storage unit, and the same color set as the selected pixel is set. Out of the laser output data storage unit, and selects the same color as the drawing color from the pixels, and outputs the laser output data corresponding to the selected color with the laser output data of the drawing color. And a laser output control method for a wet electrophotographic printer.

According to the present invention, the laser power can be changed in response to a change in conditions, such as when colors are overlapped or when colors are not overlapped.
The effect of being able to reduce the capacity of the storage device that holds the laser output data can be obtained.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an entire wet electrophotographic printing machine 1 including a laser output control device for a wet electrophotographic printing machine according to the present embodiment. The wet electrophotographic printing machine 1 converts drawing data created based on print image data into, for example, Y (yellow), M (magenta),
(Cyan), K (black), special colors and the like are sequentially superimposed to form an image formed by image-on-image printing. Have.

In the vicinity of the photosensitive drum 2, a charging device 3 as a charging means for charging the photosensitive drum 2 with an electrostatic charge, and a laser is applied to the charged photosensitive drum 2 for a certain period of time. 2 is provided with an exposure device 4 as exposure means for drawing an image to form an electrostatic latent image.

Below the photosensitive drum 2, for example, a developing means 19 for developing an electrostatic latent image formed on the photosensitive drum 2 with liquid toner is provided. This developing means 19
The image forming apparatus includes a developing device main body 5 and a developing roller 15 provided on the developing device main body 5.

The developing device main body 5 includes toner storage chambers 5B, 5C,.
H, 5I. The toner storage chamber 5 at the leftmost position in the figure
B, the first color of the four process colors, for example, yellow liquid toner, the second color, for example, red liquid toner in the toner storage chamber 5C, and the seventh color in the toner storage chamber 5H.
For example, liquid toner of three special colors and liquid toner of the eighth color, for example, four special colors, are stored in the toner storage chamber 5I at the rightmost position in the drawing. Although not shown, third to sixth toner storage chambers (not shown) are arranged between the toner storage chambers 5C and 5H in the figure. In each of the toner storage chambers, for example, a blue liquid toner, for example, Black liquid toner,
For example, a liquid toner of one special color, for example, a liquid toner of two special colors is stored. Note that a special color is a special color such as gold and red.

The developing roller 15 includes a plurality of developing rollers 15B, 15C... 15H corresponding to the respective toner storage chambers 5B and the like.
15I, these developing rollers 15B, 15C.
The liquid toner in each of the storage chambers 5B, 5C... 5H, 5I can be supplied to the photosensitive drum 2 by H, 15I. Each of these developing rollers 15
B, 15C... 15H, 15I are developing machine moving motors 11
By driving the developing machine moving mechanism 12, the position is adjusted to the developing position. The developing rollers 15B, 15C... 15H, 15I are rotated by a developing roller drive motor 17 while maintaining a predetermined fixed speed ratio with respect to the photosensitive drum 2.

A transfer roller 6 for pressure-transferring a printed image on the surface of the photosensitive drum 2 is arranged, for example, above the photosensitive drum 2. In addition, above the transfer roller 6,
A backup roller 7 that backs up the transfer roller 6 from above to prevent escape of pressing due to the deflection of the transfer roller 6, applies a strong printing pressure to the whole, and prints on the printing paper W inserted between the transfer roller 6 and the backup roller 7. And a control means 20 for controlling the entirety of the printing press 1 including the drive of the photosensitive drum 2, the transfer roller 6, etc. and the laser output control device 30 (see FIG. 3) of the printing press. .

The photosensitive drum 2 is provided with a servo motor 8, the transfer roller 6 is provided with a servo motor 9, and the backup roller 7 is provided with a servo motor 10. The servo motors 8, 9, and 10 are driven by these servo motors. The photosensitive drum 2, the transfer roller 6, and the backup roller 7 are configured to be driven synchronously under the control of the control unit 20.

As shown in FIG. 2, the exposure unit 4 includes a polygon scanner 91 rotating at a constant speed, and an fθ lens 92 for condensing a laser beam from the polygon scanner 91.
And a laser emission source 93 for making a laser incident on the polygon scanner 91. The laser output from the laser emission source 93 scans by rotating the polygon scanner 91 and prints via the fθ lens 92. The drawing on the photosensitive drum 2 by the data (drawing data) is performed from the drawing origin C to the drawing end point D which is the drawing end position.

The laser output data controlled by the laser output control device 30 shown in FIG. 3 is output to such a laser emission source 93, and a clear image can be obtained even in a portion where colors overlap. ing. The laser output control device 30 includes a PC unit 40 having data to be printed (drawing data), a main control unit 50, and a laser driving unit 60. The main control unit 50 includes a CP as a laser control unit for managing the whole.
U unit 51, interface unit 5 for receiving drawing data
2. A color combination data storage unit 54 that communicates with the CPU unit 51 via the bus 53 and stores drawing data, and a laser output data storage unit that stores laser output value data corresponding to each color of the color combination data. And a laser output interface section 56 for transmitting laser output data to the laser drive section 60. The laser driving section 60 has the laser emission source 93.

Image data created in an external DTP environment is input to the PC unit 40 via formats such as PS, EPS, and PDF.
Processing is performed. When performing RIP processing, the resolution (600 dpi, 1000 dpi, 1200 dpi) specified separately
i, 2400 dpi, etc.), and a color separation process is also performed. As shown in FIG. 5, Y color drawing data, M color drawing data, C color drawing data, and K color drawing data. The drawing data and the drawing data B of the drawing data for the spot colors 1 to 4 are formed.

Each of these data is created as follows. First, an original image (drawing data), which is data to be printed, is divided into pixel units according to a predetermined resolution and becomes pixel data A as shown in FIG. In FIG. 4, the pixel direction of 1 → 2 → 3 →→ 16 is the main scanning direction. For example, pixel 1 corresponds to the drawing start position C in FIG. 2, and for example, pixel 16 corresponds to the drawing end in FIG. It corresponds to position D. The sub-scanning direction is 1 → 17 →
33 →→ 145 pixels. By the RIP process and the color separation process, the original image corresponds to the above pixel unit, and “1” when the pixel contains the Y, M, C, and K color components.
Is set to each pixel position when no color component is included, and the drawing data as shown in FIG. 5 is created. That is, this drawing data is data in which the pixel position is determined for each color.

When the drawing data shown in FIG. 5 is created, the drawing data of each color has a byte data structure, and the first byte has bit 7 as pixel 1, bit 6 as pixel 2,. To correspond to. In the second byte, bit 7 corresponds to pixel 9, bit 6 corresponds to pixel 10,... Bit 0 corresponds to pixel 16. Hereinafter, each pixel is sequentially associated with the third byte and the fourth byte. The data created as described above becomes drawing data of each color (one pixel is one dot). Although not shown, the spot colors 1 to 4 are processed in the same manner as described above.

In the drawing data of FIG. 5, a black square represents a drawn portion, that is, a portion of "1" containing a color component, and a white square represents an undrawn portion, that is, a color. Represents the "0" part that contains no component. For example, in the first pixel, the third pixel, and the fifth pixel,
Are drawn, and the special color 3 is drawn at the first pixel, the second pixel, and the seventh pixel. At the stage of this drawing data, it is necessary to determine the laser output value for 8 bits for each pixel of each color (when the laser output resolution is 256 gradations). The drawing data of each color created as described above is input from the PC unit 40 to the interface unit 52 of the main control unit 50.

FIG. 6 shows color combination data C obtained by changing the drawing data in which the pixel position is determined for each color shown in FIG. 5 to the data in the pixel arrangement order. The color combination data C indicates a color combination state for each pixel. For example, the first pixel has Y, M, C, K, special 1, special 2, special 3, special 4, and so on. A state in which all eight colors are combined is shown. For example, the third pixel shows a state in which Y, C, special 1 and special 4 colors are combined. Although FIG. 6 shows only the color combinations up to the eighth pixel, the state of color combinations up to 160 pixels is shown corresponding to FIG. After being edited by the CPU unit 51, such color combination data is transmitted to the color combination data storage unit 54 via the bus 53,
It is stored in the storage unit 54.

FIG. 7 shows the laser output data storage 5
5 are shown. This table shows all combinations of the eight colors, and
Laser output data D indicating the output value of the laser corresponding to each color is stored. In FIG. 7, the table address column 55A is provided with 256 from 0 to 255 as table addresses for eight colors. Further, an output data column 55B is provided, for example, adjacent to the table address column 55A. In the output data column 55B, output data 0, 100, 120, etc. corresponding to the respective table addresses 0 to 255 are set in advance. I have. In addition,
The output data is predetermined and set in accordance with the rotation speed of the photosensitive drum 2, the characteristics of the liquid toner, etc., and based on experience.

The table is used in such a manner that, at a certain drawing position, for example, at the time of Y drawing, when the Y drawing data is "0", the table address column 55A is "0" and the Y drawing data is "1". Time table address column 5
5A selects “1” and refers to the output data of the address “1”, for example, 100. For example, at the time of M drawing, when the M drawing data is “0”, the table address column 55A is “0”, and when the M drawing data is “1” and Y is drawn at the pixel position, the table address column 55A is “3” is selected, and the output data of the address “3”, for example, 220 is referred to. When the M drawing data is “1” and Y is not drawn at the pixel position, “2” is selected in the table address column 55A, and the output data of the address “2”, for example, 120 is referred to.

For example, at the time of C drawing, the C drawing data is "0".
, The table address column 55A is “0”, the C drawing data is “1”, and Y is drawn at the pixel position,
When M is not drawn, “5” is selected in the table address column 55A, and the output data of the address “5”, for example, 230 is referred to. When the C drawing data is “1”, Y is drawn at the pixel position, and M is also drawn, “7” is selected in the table address column 55A, and the output data of the address “7”, for example, 235 refer. If the C drawing data is “1” and Y is not drawn at the pixel position and M is drawn, the table address 55A
And output data of the address “6”, for example, 2
Reference is made to FIG. Thereafter, in the same manner, B drawing, special colors 1 to
It is also used in the case of drawing the spot color 4. Further, in FIG. 7, the table address is described only up to the 18th,
Actually, it has 256 addresses from 0 to 255.

Next, the operation of the present embodiment will be described. After the operation of the printing press 1 is started and the surface of the photosensitive drum 2 is charged, when the photosensitive drum 2 rotates and reaches the exposure position, an electrostatic latent image is formed on the surface of the photosensitive drum 2 by the exposure unit 4. Is formed.

When a laser is output to form an electrostatic latent image, the CPU 51 of the main control unit 50 calls color combination data C as shown in FIG. Find the laser output data of the color to be drawn. At this time, the CPU unit 51 selects a color to be drawn from the color combination data of each pixel in the color combination data storage unit 54, selects a pixel having that color, and sets a color combination of the selected pixel. From the combination of colors for each pixel stored in the laser output data storage unit 55, laser output data corresponding to the selected color is selected, and the laser output data is output to the laser output interface unit 56. . The laser output data is input from the laser output interface unit 56 to the laser emission source 93 of the laser drive unit 60,
As a result, a laser having a predetermined output value is reflected by the polygon scanner 91 and scans the surface of the photosensitive drum 2 to form a clear electrostatic latent image.

In the above embodiment, the following effects can be obtained. (1) The output value of the laser of the color to be drawn is determined by selecting the color to be drawn from the color combination data, selecting the pixel incorporating the color to be drawn, and selecting the pixel of the same color combination as the selected pixel. Since the laser output data of the color to be selected and drawn from the laser output data storage unit may be used, the laser power can be changed in accordance with a change in the condition, such as when the colors are overlapped or not overlapped. And a clear image can be obtained.

(2) The laser output value of the color to be drawn may be determined with reference to the laser output data storage unit 55 in which laser output data for each color is stored for each of a plurality of color combinations. Since the data corresponds to the color combination data B in which the drawing data A is formed for each pixel, for example, the resolution of the laser output is 256.
Since 8-bit data per dot required for gradation is not required, the data can be reduced to 1/8, thereby reducing the capacity of the storage device for holding the laser output data. can do.

(3) The printing machine 1 according to the present embodiment includes Y, M, etc.
Since the eight colors are drawn by appropriately overlapping each other, multicolor printing can be performed, and it is possible to meet various demands of users. (4) Since the laser output data is set in the laser output data storage unit 55 so as to correspond to all combinations when eight colors are combined, the laser output data is determined for the color to be drawn. There's no way you can't.

The present invention is not limited to the above-described embodiment, but may be modified as follows as long as the object of the present invention can be achieved. That is, the printing machine of the embodiment is a printing machine that draws by superimposing eight colors, but is not limited to this. For example, a printing machine that superimposes and draws four colors excluding the spot colors 1 to 4 Machine.

[0037]

According to the laser output control device and the control method of the wet electrophotographic printing machine of the present invention, the output value of the laser of the color to be drawn can be selected from the color combination data by selecting the color to be drawn. A pixel in which the color to be drawn is incorporated is selected, a pixel having the same color combination as the selected pixel is selected from the laser output data storage unit, and the same color as the color to be drawn is selected from the pixels in the laser output data storage unit. Select the laser output data corresponding to the selected color, and use it as the laser output value of the color to be drawn. Thus, a clear image can be obtained.

The laser output value of the color to be drawn may be determined by referring to a laser output data storage section in which laser output data for each color is stored for each combination of a plurality of colors. Since the drawing data corresponds to the combination data of the colors formed for each pixel, for example, 8-bit data per pixel, which is required when the resolution of the laser output is 256 gradations, becomes unnecessary. The capacity of a storage device that holds output data can be reduced.

[Brief description of the drawings]

FIG. 1 is an overall view showing a wet electrophotographic printing machine according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a relationship between an exposure unit and a photosensitive drum according to the embodiment.

FIG. 3 is a diagram showing control means of a wet electrophotographic printing machine including the laser output control device of the embodiment.

FIG. 4 is a data diagram when the original image of the embodiment is shown in pixel units.

FIG. 5 is a diagram showing data in which pixel positions are determined for each color formed based on the data of FIG. 4;

FIG. 6 is a diagram showing color combination data obtained by changing the data of FIG. 5 to data in the pixel arrangement order.

FIG. 7 is a diagram showing contents of a laser output data storage unit of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printing machine 2 Photoreceptor drum 3 Charger 4 Exposure device 6 Transfer roller 7 Backup roller 19 Developing means 30 Laser control unit 40 PC unit 50 Main control unit 51 CPU unit 54 Color combination data storage unit 55 Laser output data storage unit 60 Laser Drive unit 93 Laser light source

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 1/29 B41J 3/00 D 5C079 1/46 H04N 1/46 Z (72) Inventor Mitsuhiko Iida Kanagawa 4-5676 Hibarigaoka, Zama City Toshiba Machine Co., Ltd. Sagami Factory (72) Inventor Makoto Hayashi 4-5676 Hibarigaoka, Zama City, Kanagawa Prefecture Toshiba Machine Co., Ltd. Sagami Factory (72) Inventor Junji Tsunekawa 4 Hibarigaoka, Zama City, Kanagawa Prefecture 5676-chome F-term in the Sagami Plant of Toshiba Machine Co., Ltd. (reference) DD24 FF15 GG02 GG12 5C079 HB03 KA03 KA08 KA17 KA18 LA02 MA01 MA02 NA01 NA10 PA07

Claims (3)

[Claims] 1. A photosensitive drum on which an image is formed on a surface, a charging unit for charging the surface of the photosensitive drum,
A wet type comprising: an exposure unit that irradiates a laser to the surface of the photoconductor drum to form an electrostatic latent image; and a development unit that develops the electrostatic latent image on the photoconductor drum by superimposing a plurality of colors. A laser output control device for an electrophotographic printing machine, comprising: a laser output data storage unit in which laser output data for each color is stored for each combination of the plurality of colors; and drawing data as color combination data for each pixel. A stored color combination data storage unit, and a laser control unit that selects the laser output data corresponding to the color to be drawn and controls the laser, wherein the laser control unit stores the color to be drawn While selecting from the color combination data of the color combination data storage unit, selecting a pixel in which the color to be drawn is incorporated, and selecting a pixel having the same color combination as the selected pixel The same color as the color to be drawn is selected from among the pixels in the laser output data storage unit, and laser output data corresponding to the selected color is set as the laser output data of the color to be drawn. Output control device of wet electrophotographic printing machine. 2. A laser output control apparatus for a wet electrophotographic printing machine according to claim 1, wherein said plurality of colors comprise at least two colors. Control device. 3. A photosensitive drum on which an image is formed on the surface, a charging unit for charging the surface of the photosensitive drum,
An exposure unit that irradiates a laser on the surface of the photoconductor drum to form an electrostatic latent image; and a developing unit that develops the electrostatic latent image on the photoconductor drum by superimposing a plurality of colors, What is claimed is: 1. A laser output control method for a wet electrophotographic printing press, wherein a laser is controlled by a control unit, wherein a laser output data storage unit stores laser output data for each color for each combination of the plurality of colors, and stores color combination data. The drawing data is stored in the unit as color combination data for each pixel, and the color to be drawn is selected by the laser control unit from the color combination data in the color combination data storage unit, and the same color as the selected pixel is stored. Pixel from the laser output data storage unit, and the same color as the color to be drawn is selected from the pixels, and corresponds to the selected color. A method for controlling laser output of a wet electrophotographic printing machine, wherein the laser output data to be rendered is the laser output data of the color to be drawn.