JP2006224528A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To represent a thin line without carrying out controlling of a plurality of processes. <P>SOLUTION: This image forming apparatus develops an input image to bitmap data, and scans the image in a main scanning direction by each two pixels. When pixel values of two scanned pixels are ON data, the image forming apparatus scans a photosensitive drum 90 in the main scanning direction by a laser light such that an exposure width of the two pixels in the main scanning direction is made to be a predetermined fixed width. When the pattern of the pixel values of the scanned pixels is "01" or "10", the image forming apparatus scans the photosensitive drum 90 in the main scanning direction by the laser light such that an exposure width in the main scanning direction of one pixel of which the pixel value is the ON data is made to be one stored in a memory section 20. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technique for improving the image quality of an image formed by an image forming apparatus.

In recent years, it has been desired to increase the resolution of an output image in an image forming apparatus. However, in the electrophotographic image forming apparatus, there is a problem that the reproducibility of fine lines is lowered when the resolution is increased so that finer line segments can be formed. Therefore, as a technique for improving the reproducibility of thin lines, for example, a technique disclosed in Patent Document 1 has been devised. The image forming apparatus disclosed in Patent Document 1 controls the latent image condition and the development condition when the ratio of the dot-shaped laser light irradiated to the photoconductor and the output interval of the laser light exceeds a certain value. The reproducibility of fine lines is improved by widening the development contrast.
Japanese Patent Laid-Open No. 5-107886

  By the way, the image forming apparatus disclosed in Patent Document 1 sets the latent image condition and the development condition when the ratio of the dot-shaped laser light irradiated to the photoconductor and the output interval of the laser light exceeds a certain value. Although the control is to improve the reproducibility of fine lines, the development conditions must be controlled in addition to the latent image conditions, which requires complicated control.

  The present invention has been made under the above-described background, and an object thereof is to provide a technique capable of reproducing a thin line without controlling a plurality of processes.

  In order to solve the above-described problems, the present invention provides an image carrier having a photosensitive layer having photoconductivity, charging means for charging the image carrier, and one pixel in the main scanning direction of the image carrier. Storage means for storing the exposure width of the image, image scanning means for scanning the image represented by the input binary image data by two pixels in the main scanning direction, and pixel values of the two pixels scanned by the image scanning means. When both are ON, the image carrier is scanned with the laser beam in the main scanning direction so that the exposure width of two pixels in the main scanning direction in the charged image carrier becomes a predetermined fixed width. When only one of the two pixels scanned by the image scanning unit is ON, the exposure width in the main scanning direction for one pixel whose pixel value is ON is stored in the storage unit. So that the exposure width is To provide an image forming apparatus having an exposure unit for scanning in the main scanning direction of the image bearing member by a laser beam.

  According to the present invention, a thin line can be reproduced without controlling a plurality of processes.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Constitution]
FIG. 1 is a block diagram showing a main configuration of an electrophotographic image forming apparatus according to an embodiment of the present invention. This image forming apparatus is an intermediate transfer type image forming apparatus, and includes an image forming unit that forms a toner image for each color of Y (Yellow), M (Magenta), C (Cyan), and K (black). Yes. Each image forming unit has the same configuration except that the color of the toner image to be formed is different. Here, in order to prevent the drawing from becoming complicated, the image forming unit 1 that forms a black image, which is one of them, will be described, and the description of the image forming units of other colors will be omitted.

The control unit 10 includes a ROM, a RAM, and a CPU (all not shown), and controls each unit of the image forming apparatus according to a program stored in the ROM.
A UI (User Interface) unit 40 includes various keys for operating the image forming apparatus. When the provided key is pressed, the UI unit 40 outputs a signal indicating the pressed key to the control unit 10. The UI unit 40 includes a display device such as a liquid crystal display, and displays a menu screen for operating the image forming apparatus, various messages, and the like under the control of the control unit 10.
The storage unit 20 includes a device that permanently stores data, such as a hard disk device, and stores various data for controlling the image forming apparatus. Note that the data stored in the storage unit 20 can be rewritten by the user operating the UI unit 40.
The communication unit 30 is connected to a communication network (not shown) such as a LAN (Local Area Network) and functions as a communication interface for performing data communication via the communication network. When the communication unit 30 receives data described in a page description language (hereinafter referred to as PDL (page description language)) transmitted from a computer device connected to the communication network, the communication unit 30 transmits the received PDL data to the control unit 10. To supply.

  The decompression unit 50 is connected to the control unit 10 and receives PDL data supplied from the control unit 10. When the PDL data is input, the decomposing unit 50 interprets the input PDL data and generates images of Y, M, C, and K colors. In addition, the decomposing unit 50 performs screening processing and gradation correction processing on the generated image, and generates bitmap data representing images of characters and photographs formed on the recording paper for each color of Y, M, C, and K. To do. The decompression unit 50 outputs the generated bitmap data to the pattern recognition unit 60. In the present embodiment, this bitmap data is binary image data in which the value of each pixel is represented by 1 bit, and the pixel of the portion recorded as an image such as a character or a photo is “1 (ON)”. The pixels in the blank portion are “0 (OFF)”.

  The pattern recognition unit 60 analyzes the image represented by the input bitmap data and performs pattern recognition of the pixels forming the image. Specifically, the pattern recognition unit 60 extracts pixels that form an image two pixels at a time in the main scanning direction. In the bitmap data input to the pattern recognition unit 60, the value of each pixel is represented by 1 bit. Therefore, when two pixels are extracted, the extracted pixel value pattern is shown in FIG. As shown, it is any one of “00 (A pattern)”, “10 (B pattern)”, “01 (C pattern)”, and “11 (D pattern)”. The pattern recognition unit 60 specifies which of the four patterns the extracted two pixel patterns correspond to, and outputs a pattern signal representing the specified pattern to the pulse modulator 70.

  The photosensitive drum 90 is a member in which a photosensitive layer having photoconductivity is laminated on the outer periphery of a cylindrical base material, and is charged by a charger 100 that charges the photosensitive drum 90 to a constant potential.

The pulse modulator 70 is a device that outputs a drive signal instructing output of laser light to an exposure device 80 described later. Based on the pattern signal output from the pattern recognition unit 60, the pulse modulator 70 generates a drive signal that instructs the output of the laser light, and outputs the generated drive signal to the exposure apparatus 80.
Specifically, when a pattern signal representing an A pattern is input, the pulse modulator 70 outputs laser light in the main scanning direction with a width of two pixels as shown in FIG. A drive signal A instructing not to be generated is generated and output. In addition, when a pattern signal representing a D pattern is input, the pulse modulator 70 outputs laser light in the main scanning direction with a width of two pixels as shown in FIG. A drive signal B to be instructed is generated and output.
When a pattern signal representing a B pattern is input to the pulse modulator 70, as shown in FIG. 3B, the pulse modulator 70 has an exposure width W for a pixel whose value is “1”. A drive signal C for instructing to output laser light in the main scanning direction is generated and output.
Further, when a pattern signal representing a C pattern is input to the pulse modulator 70, as shown in FIG. 3C, an exposure width W is applied to a pixel having a value of “1”. A drive signal D instructing to output the laser beam in the main scanning direction is generated and output.
Here, the exposure width W is set by exposure width data supplied from the control unit 10. The exposure width data is stored in the storage unit 20, and the control unit 10 reads it from the storage unit 20 and supplies it to the pulse modulator 70. Note that the exposure width data stored in the storage unit 20 can be changed in content by the user operating the UI unit 40.

  The exposure device 80 is a device that irradiates the photosensitive drum 90 with laser light. The exposure device 80 outputs laser light according to each drive signal output from the pulse modulator 70 to expose the photosensitive drum 90. When the exposure device 80 outputs laser light to the photosensitive drum 90, an electrostatic latent image is formed on the photosensitive drum 90. Specifically, when the driving signal A is input, the exposure apparatus 80 performs scanning in the main scanning direction and does not output laser light by a width corresponding to two pixels. Further, when the drive signal D is input, the exposure device 80 outputs laser light by a width corresponding to two pixels while performing scanning in the main scanning direction. Further, when the drive signal B is input, the exposure device 80 outputs laser light for the exposure width W while performing scanning in the main scanning direction. Further, when the drive signal C is input, the exposure device 80 outputs laser light for the exposure width W while performing scanning in the main scanning direction.

  The developing device 110 is a device that attaches toner to the electrostatic latent image formed on the photosensitive drum 90 by the exposure device 80. The toner image formed on the photosensitive drum 90 by the developing device 110 is transferred to the intermediate transfer belt 130 by the transfer roll 140. The cleaning device 120 is a device that removes toner on the photosensitive drum 90. After the photosensitive drum 90 comes into contact with the intermediate transfer belt 130, the toner remaining on the photosensitive drum 90 is removed by the cleaning device 120.

[Operation]
Next, the operation of this embodiment will be described.
First, when the image forming apparatus is turned on, the control unit 10 controls each part of the image forming apparatus to initialize the image forming apparatus. Here, the control unit 10 reads the exposure width data stored in the storage unit 20 and supplies the read exposure width data to the pulse modulator 70. Next, PDL data is transmitted from a computer device connected to the communication network, and when the PDL data is received by the communication unit 30, the received PDL data is supplied to the control unit 10. When the PDL data is supplied, the control unit 10 supplies the supplied PDL data to the decompression unit 50. Further, the photosensitive drum 90 is rotated and the charger 100 is controlled to charge the photosensitive drum 90.

  When the PDL data is supplied, the decomposing unit 50 generates images of Y, M, C, and K colors based on the input PDL data. After the generated image is subjected to screening processing and gradation correction processing, bitmap data for each color image is generated, and the generated bitmap data is output to the pattern recognition unit 60.

  The pattern recognition unit 60 analyzes the image represented by the input bitmap data and performs pattern recognition of the pixels forming the image. For example, as shown in FIG. 4A, when bitmap data having a pixel value “01001011” is input, the pattern recognition unit 60 performs “01”, “00”, “10”, As in “11”, two pixels are extracted in the main scanning direction. Then, pattern recognition of the extracted pixels is performed, and it is specified that the pixel patterns are in the order of C pattern, A pattern, B pattern, and D pattern. When the pattern recognition unit 60 specifies the extracted pixel pattern, the pattern recognition unit 60 outputs a pattern signal indicating the specified pattern.

  When the pattern signal is input, the pulse modulator 70 generates a drive signal instructing the output of the laser light based on the input pattern signal, and outputs the generated drive signal to the exposure apparatus 80. In the case of the bitmap data described above, the pattern signals are input in the order of the pattern signal of the C pattern, the pattern signal of the A pattern, the pattern signal of the B pattern, and the pattern signal of the D pattern. The pulse modulator 70 generates and outputs drive signals in the order of drive signal C, drive signal A, drive signal B, and drive signal D based on the input pattern signal. Here, since the exposure width data is supplied from the control unit 10 to the pulse modulator 70, the value becomes “1” when the pulse modulator 70 generates the drive signal B and the drive signal C. A drive signal for instructing to output laser light in the main scanning direction by the exposure width W is generated and output to the pixel being exposed. When the driving signal is input, the exposure device 80 outputs a laser beam in accordance with the driving signal to expose the photosensitive drum 90. Here, as described above, when the pattern signals are output in the order of the pattern signal of the C pattern, the pattern signal of the A pattern, the pattern signal of the B pattern, and the pattern signal of the D pattern, as shown in FIG. As described above, the photosensitive drum 90 is exposed.

  As described above, in this embodiment, the vertical line portion and the diagonal line portion formed by one pixel as shown in FIG. 5 are exposed to the photosensitive drum 90 with the set exposure width W. Since the exposure width W can be changed by a user operation, if the exposure width data is changed to increase the exposure width W, the exposure amount in the main scanning direction is increased and a thin line formed by one pixel. And the reproducibility of diagonal lines can be improved. In addition, in a portion where pixels are continuous as in the D pattern, as shown in FIG. 3D, exposure is performed with a constant exposure amount, so that a solid image can be formed without increasing the image density. . In addition, the reproducibility of fine lines and diagonal lines can be improved by controlling the exposure amount without controlling the development process and the fixing process, that is, controlling the latent image forming process. Don't be complicated.

[Modification]
As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment mentioned above, It can implement with another various form. For example, the present invention may be implemented by modifying the above-described embodiment as follows.

  In the above-described embodiment, the intermediate transfer type image forming apparatus has been described as an example. However, in another type of image forming apparatus, the exposure width W for one pixel can be varied as in the above-described embodiment. It may be.

1 is a diagram illustrating a main configuration of an image forming apparatus according to an embodiment of the present invention. It is a figure which shows the pattern of the pixel extracted by the pattern recognition part. It is the figure which represented typically the width | variety of the laser beam which the exposure apparatus 80 outputs. It is a figure for demonstrating the operation | movement of embodiment. It is a figure for demonstrating the operation | movement of embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Control part, 20 ... Memory | storage part, 30 ... Communication part, 40 ... UI part, 50 ... Decompose part, 60 ... Pattern recognition part, 70 ... Pulse modulator 80 ... exposure device, 90 ... photosensitive drum 900 ... charger, 110 ... developing device, 120 ... cleaning device, 130 ... intermediate transfer belt, 140 ... transfer roll .

Claims (2)

An image carrier provided with a photosensitive layer having photoconductivity;
Charging means for charging the image carrier;
Storage means for storing an exposure width for one pixel in the main scanning direction of the image carrier;
Image scanning means for scanning the image represented by the input binary image data by two pixels in the main scanning direction;
When the pixel values of the two pixels scanned by the image scanning unit are both ON, the exposure width of two pixels in the main scanning direction on the charged image carrier is set to a predetermined fixed width. When the image carrier is scanned with a laser beam in the main scanning direction and only one pixel value of two pixels scanned by the image scanning unit is ON, the pixel value is ON for one pixel. An image forming apparatus comprising: an exposure unit that scans the charged image carrier in the main scanning direction with a laser beam so that an exposure width in a main scanning direction becomes an exposure width stored in the storage unit.   The image forming apparatus according to claim 1, further comprising an exposure width changing unit that changes the exposure width stored in the storage unit in accordance with an externally input signal.

Images