JP2003222964A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the uneven luminance of an image by correcting the light quantity of a light source in channels at both ends. <P>SOLUTION: The characteristics of photosensitive material and the characteristics of a light beam radiated from an optical unit are measured, and a correction value for adjusting the light quantity in the channels at both ends is generated based on the measured value. The correction value is previously stored in a ROM 602 as a light quantity correction table classified by material 800. By performing a light quantity correction program 803, a CPU 600 reads out the table 800 and corrects the light quantity for digital image data. <P>COPYRIGHT: (C)2003,JPO

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 that forms an image by exposing a photosensitive material with a plurality of light sources, and particularly, among the plurality of light sources, image unevenness can be obtained by adjusting the light amount of the light sources at both ends. The present invention relates to an image forming apparatus for preventing.

[0002]

2. Description of the Related Art As an image forming apparatus for forming an image by exposing a photosensitive material with a plurality of light sources, for example, a color proof (proof material) for confirming image data for forming an original plate of a printing plate is prepared. A color image recording device and the like can be mentioned.

In such an image forming apparatus, light beams of a plurality of colors such as red, green and blue are generated from different light emitting elements, respectively, combined as one light beam, and irradiated on the photosensitive material. As the light emitting element, a light emitting diode (hereinafter,
Say "LED". ), A semiconductor laser, or the like is used, and the light amount of the light beam irradiated by these is changed stepwise based on image data to expose the photosensitive material to form a color image.

A light source is formed by combining light beams emitted from a plurality of light emitting elements into one light beam, and one of the plurality of light sources is called one channel. The image forming apparatus includes an optical unit in which a plurality of channels are arranged in the sub scanning direction. Then, the optical unit irradiates the photosensitive material rotating in the main scanning direction with a light beam to form an image, thereby forming an image.

In this case, when the photosensitive material makes one rotation in the main scanning direction, the optical unit is moved in the sub scanning direction by the width of the light beam. Image exposure is performed by irradiating the next recording area with a light beam. Alternatively, the operations in the main scanning direction and the sub scanning direction may be coordinated. At this time, the optical unit moves spirally on the photosensitive material. Here, a portion where the photosensitive material is imagewise exposed by a light beam in one main scanning is called a recording area.

[0006]

In the image forming apparatus having a plurality of channels as described above, the image formed on the photosensitive material is imaged due to the material characteristics of the photosensitive material and manufacturing variations at the time of factory assembly of the optical unit. There is a problem that unevenness occurs.

FIG. 11A is a diagram showing the light quantity of the n-channel light beam emitted from the optical unit according to the position coordinates of each channel. The diagram shown in the upper part of FIG. 11A shows the shape of the light beam with which the exposed surface of the photosensitive material is irradiated. In the shape of the light beam, dots 100-1, 100-2, ... 100-n (hereinafter,
Collectively referred to as "dot 100". ). here,
The center of the light beam emitted from channel 1 is dot 100-1, and the center of the light beam emitted from channel n is dot 100-n.

Then, the portions of the light that spread from the dot 100 to the periphery are divided into peripheral portions 101-1, 101-2 ,.
························ 101-n (hereinafter, collectively referred to as “peripheral part 101”). In addition, the waveform N1 in the diagram of FIG.
N2, ..., Nn are light amount characteristics of channels 1, 2 ,.

In FIG. 11 (a), channels (hereinafter, referred to as "channels in the central portion") excluding channel 1 and channel n (hereinafter referred to as "channels at both ends") of a light beam having n channels are referred to as "channels in the central portion". ), The light beams emitted from (1) and (2) overlap with the light beams emitted from adjacent channels in the peripheral portion 101. As a result, the light amount of the light beam received by the exposed surface of the photosensitive material from the central channel becomes uniform.

However, the channels on both ends do not have adjacent channels on one side. As a result, as shown in FIG. 11A, the light amount of the light beam received by the exposed surface of the photosensitive material from the channels at both ends sharply decreases.

FIG. 11B is a diagram showing the color density of the photosensitive material exposed by the light beam emitted from the optical unit according to the position coordinates of each channel. Figure 11
In (b), the solid line indicates the concentration characteristic of the material a, and the alternate long and short dash line indicates the concentration characteristic of the material b. Materials a and b are photosensitive materials having different material properties.

FIG. 12 is a diagram showing the material characteristics of the materials a and b. The density X is an appropriate density when forming an image on the photosensitive material. When the materials a and b are exposed to a light beam having a light amount Y, a color having a density X, which is an appropriate density, is developed in both materials. However, when the light amount of the light beam is reduced and the light beams of the light amount Y ′ are exposed to the materials a and b, the material a has a density X _A and the material b has a density X _B.

As described above, due to the difference in the material characteristics of the light-sensitive material, the density of color development may differ even when the light beams of the same light quantity are used for exposure. Therefore, as shown in FIGS. 11A and 11B, the densities of the images formed are different at both ends of the recording areas of the materials a and b because the exposure amount by the light beam is reduced. As a result, there is a problem that density unevenness occurs in the formed image and the image quality is impaired.

As a countermeasure against this problem, for example, FIG.
Assuming that (a) is the light amount characteristic for n channels in the mth main scan, the peripheral parts 101-n and m + in the mth main scan are compensated for in order to compensate for the decrease in the light amount of the peripheral part 101-n.
The movement of the optical unit in the sub-scanning direction may be controlled so that the peripheral portion 101-1 in the first main scanning overlaps. However, it is necessary to change the moving width in the sub-scanning direction according to the material characteristics of the photosensitive material. In addition, it may be difficult to realize because the characteristics of color development with respect to the light amount of the light emitting element of each hue may be different, and the size of the printed image may change due to the change of the movement width in the sub operation direction. is there.

As another countermeasure, a method may be considered in which the pitch p is adjusted so that the peripheral portion 101-n in the m-th main scanning and the peripheral portion 101-1 in the m + 1-th main scanning overlap each other. However, similarly to the above, it is difficult to change the pitch p according to the difference in material characteristics of the photosensitive material.

Further, due to manufacturing variations that occur when the optical units are assembled in a factory, the light quantity characteristics of the light beam emitted by the optical units may differ from one optical unit to another. In such a case, it is necessary to further take the above-mentioned measures in accordance with the light amount characteristics of each optical unit, which is more difficult to realize.

As a known technique, for example, Japanese Patent Laid-Open No. 10-1
As in Japanese Patent No. 81085, there is known a method of correcting the light amount of the light beam emitted from the channels at both ends according to one movement amount in the sub-scanning direction. However, since a detection circuit for detecting the amount of movement in the sub-scanning direction is required, the structure of the image forming apparatus becomes complicated. In addition, JP-A-6
There is known a method in which a correction laser beam is provided for channels at both ends and the intensity of the laser beam is changed according to image data, as in Japanese Patent Publication No. 1989952. However, when the intensity of the laser beam emitted from the channels at both ends is high, it is impossible to subtract the intensity by the correction laser beam.

An object of the present invention is to provide an image forming apparatus in which the light quantity of the light source in the channels at both ends is corrected to prevent uneven density of the image.

[0019]

In order to solve the above-mentioned problems, the invention according to claim 1 has a light source means having a plurality of light sources arranged in a row, and an exposure for controlling the light quantity of each light source. An image forming apparatus that includes a control unit and forms an image while performing exposure of a predetermined width on a photosensitive recording medium by simultaneously irradiating the light beams of the respective light sources. Further, a storage unit for storing the light amount correction data of the light sources at one end and the other end is provided, and the exposure control unit sets the desired light amount for the light source at the one end and the other end to the light amount correction data stored in the storage unit. The light amount of the light source at the one end and the light amount at the other end are controlled by correcting the light amount.

According to the first aspect of the present invention, among the light sources of the light source means, the light sources at one end and the other end are corrected based on the light amount correction data to adjust the light amounts of the light sources at the one end and the other end. can do. Therefore, when the photosensitive recording medium is exposed by using the light source means to form an image, the amount of exposure of the recording medium by the light sources at one end and the other end can be adjusted. As a result, it is possible to reduce image unevenness that has occurred due to a decrease in the amount of exposure of the recording medium by the light sources at one end and the other end.

Further, the invention according to a second aspect is the image forming apparatus according to the first aspect, further comprising a data value varying means for varying the light amount correction data stored in the storage means. .

According to the second aspect of the invention, the value of the light quantity correction data can be changed by using the data value changing means for changing the value of the light quantity correction data.
Thereby, the adjustment amount of the light amount of the light source at the one end and the other end of the light source means can be arbitrarily set.

The invention according to claim 3 is the image forming apparatus according to claim 1 or 2, wherein the storage means is based on a plurality of types of the recording medium and characteristics of the recording medium of each type. The light quantity correction data that has been set is stored, further comprising a selection means for selecting one of the plurality of types of the recording medium stored in the storage means, and the exposure control means is configured by the selection means. The correction is performed based on the light amount correction data corresponding to the selected type of recording medium.

According to the third aspect of the present invention, the light quantity correction data is stored in the storage means for each characteristic of the recording medium, and one end of the light source means and the light quantity correction data corresponding to the characteristics of the recording medium to be used are stored. By adjusting the light amount of the light source at the other end, the exposure amount of the light source at the one end and the other end to the recording medium can be adjusted according to the characteristics of the recording medium. As a result, it is possible to reduce image unevenness that has occurred due to a decrease in the amount of exposure of the recording medium by the light sources at one end and the other end.

According to a fourth aspect of the invention, there is provided the image forming apparatus according to the first or second aspect, wherein the storage means stores a plurality of light quantity correction data according to the arrangement conditions of the light sources of the light source means. A plurality of light quantity correction data stored in the storage means, further comprising a selecting means for selecting one light quantity correction data, the exposure control means, based on the light quantity correction data selected by the selecting means, It is characterized in that the correction is performed.

According to the fourth aspect of the invention, the light amount correction data is stored in the storage medium for each arrangement condition (for example, arrangement position) of the light source of the light source means, and the arrangement condition of the light source means to be used is stored. By adjusting the light amount of the light source at one end and the other end of the light source means based on the light amount correction data corresponding to
The exposure amount on the recording medium by the light sources at one end and the other end can be adjusted according to the difference in the arrangement conditions of the light sources. As a result, it is possible to reduce image unevenness that has occurred due to a decrease in the amount of exposure of the recording medium by the light sources at one end and the other end.

The invention according to claim 5 is the same as claim 1.
The image forming apparatus according to any one of claims 1 to 4, wherein each of the light sources has a plurality of light emitting elements, and the storage unit is one of the light sources at one end and the other end of the plurality of light sources included in the light source unit. The light quantity correction data of each light emitting element is stored, and the exposure control means stores the desired light quantity for each light emitting element of the light source at the one end and the other end, the light quantity correction data of the corresponding light emitting element stored in the storage means. The light emitting element of the light source at the one end and the light source at the other end is controlled based on the above.

According to the fifth aspect of the invention, each light emitting element is adjusted to a desired light amount based on the light amount correction data of a plurality of light emitting elements of different colors forming the light sources at one end and the other end of the light source means. By making the correction, it is possible to adjust the amount of light at one end and the other end. As a result, it is possible to reduce image unevenness that has occurred due to a decrease in the amount of exposure of the recording medium by the light sources at one end and the other end.

According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, the storage means sets a target light amount set according to a desired density of an image formed on the recording medium. The correction data is further stored, and the exposure control unit corrects a desired light amount with respect to the light source at the one end and the other end based on the target light amount correction data stored in the storage unit, and It is characterized by controlling the light source.

According to the sixth aspect of the present invention, even when the density of the image formed on the recording medium differs due to the difference in material characteristics or the demand of the user of the apparatus, one end and the other end of the image can be formed in accordance with the desired density. The amount of light can be adjusted. Accordingly, it is possible to reduce image unevenness of the image formed on the recording medium.

According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to sixth aspects, the recording medium is irradiated with the light beam of each of the light sources so that the recording medium is cyan, magenta, or
And an image forming apparatus for forming a color image by forming each color of yellow, wherein the exposure control means causes the light beams of the light sources at the one end and the other end to generate cyan and / or magenta on the recording medium. It is characterized in that it has a determination means for determining whether or not it corresponds, and performs the correction when it corresponds to cyan and / or magenta.

According to the seventh aspect of the invention, in image formation on the recording medium by exposure of the image forming apparatus, it is difficult for humans to visually recognize image unevenness due to yellow. Therefore, cyan and / or magenta hues are different. The light amount is corrected only for the light emitting elements that constitute the light sources at one end and the other end that irradiate the light beam that is exposed to. As a result, the light amount can be corrected more quickly than the light amount correction is performed for all the light emitting elements forming the light sources at the one end and the other end.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 illustrates an image forming apparatus 100.
It is a figure showing the composition of. The image forming apparatus 100 mainly includes a paper loading unit 1, an exposure unit 2, a development processing unit 3, and a paper discharge unit 4.

The paper loading unit 1 is installed above the exposure unit 2. A paper feed cover 11 is provided in the paper loading unit 1 so as to be openable and closable, and a dedicated cartridge 12 containing a roll-shaped photosensitive material 5 (recording medium) is set therein.

The exposure unit 2 includes a paper feed section 21 and a drum 2.
2, an optical unit 23, an accumulation unit 24, and a paper discharge unit 25, and performs image exposure of the photosensitive material 5.

The paper feed section 21 includes paper feed rollers 211a and 211b, a cutter 212 and a paper feed roller 213. Then, the pair of paper feed rollers 211a and 211
b sandwiches the photosensitive material 5 set in the paper loading unit 1 and rotates it to feed it to the drum 22. The cutter 212 cuts the photosensitive material 5 when the photosensitive material 5 having a predetermined length is fed to the drum 22. Paper feed roller 213
Presses the photosensitive material 5 onto the drum 22 so that the photosensitive material 5 is not twisted when wound around the drum 22.

The drum 22 is a photosensitive material 5 for exposing an image.
The photosensitive material 5 is exposed to the light beam emitted from the optical unit 23 while being wound and rotated in the main scanning direction (rotational direction of the drum 22).

The optical unit 23, which is a light source means, combines the light beams emitted from the light emitting elements of different colors of the red LED, the green LED and the blue LED into one light beam through the mirror and the lens, and the drum 22. While moving in the direction of the drum axis (sub-scanning direction), the photosensitive material 5 wound around the drum 22 is irradiated with the light beam. Details of the optical unit 23 will be described later.

In the accumulation section 24, the image-exposed photosensitive material 5 is hung and stored. Development processing unit 3
Since the transport speed of the photosensitive material 5 is faster than the transport speed of the exposure unit 2, the accumulation unit 24 causes the development processing unit 3 to move.
And the conveyance timing of the photosensitive material 5 in the exposure unit 2 is adjusted.

In the paper discharge section, the photosensitive material 5 hanging down from the accumulation section 24 is fed to the development processing unit 3.

The development processing unit 3 includes a second exposure unit 31,
Developing unit 32, fixing unit 33, stabilizing unit 34, and drying unit 35
And the exposed photosensitive material 5 is developed. The second exposure unit 31 exposes a pseudo image on a portion of the photosensitive material 5 that was not exposed by the exposure unit 2. In the developing unit 32, the fixing unit 33, and the stabilizing unit 34,
The photosensitive material 5 conveyed from the second exposure unit 31 is developed. The drying section 35 dries the developed photosensitive material 5 and sends it to the paper discharge section 4.

FIG. 2 shows the drum 22 of the image forming apparatus 100.
3 is a perspective view of an optical unit 23. FIG. The drum 22 around which the photosensitive material 5 is wound rotates around the drum shaft. This rotation direction is the main scanning direction. Optical unit 2
3 moves continuously from one end of the photosensitive material 5 in parallel with the drum axis. This moving direction is the sub-scanning direction.

The optical unit 23 emits a light beam while moving in the sub-scanning direction to expose the photosensitive material 5 wound around the drum 22. The light beam emitted from the optical unit 23 first exposes the portion of the photosensitive material 5 having the width a. Then, while the drum 22 makes one rotation, the optical unit 23 moves in the sub scanning direction by the width a. Therefore, the drum 22
In the second rotation, the area of the width b of the photosensitive material 5 is exposed. The values of the widths a and b are determined by the number of light sources included in the optical unit 23 and the arrangement interval of the light sources.

FIG. 3 is a diagram showing the structure of the optical unit 23. The optical unit 23 includes the light source holding block 4
1, 42 and 43, a mirror 44, dichroic mirrors 45 and 46, a lens 47 and the like.

The light source holding blocks 41, 42 and 43 are respectively provided with light emitting elements of different colors such as blue LED, green LED and red LED. The details of the configuration of the light source holding blocks 41, 42 and 43 will be described later.

The mirror 44 reflects the light beam emitted from the light source holding block 43 toward the lens 47. The dichroic mirror 45 reflects the light beam emitted from the light source holding block 42 toward the lens 47 and transmits the light beam emitted from the light source holding block 43 reflected by the mirror 44. The dichroic mirror 46 reflects the light beam emitted from the light source holding block 41 toward the lens 47, and the dichroic mirror 4
The light beam emitted from the light source holding block 42 reflected by 5 and the light beam emitted from the light source holding block 43 passing through the dichroic mirror 45 are transmitted. In the figure, the optical axis 48 shown by the alternate long and short dash line represents the trajectory of the light beam.

In this way, the light source holding blocks 41, 42
The light beams emitted from and 43 pass through the optical axis 48 via the mirror 44 and the dichroic mirrors 45 and 46, are condensed by the lens 47, and form an image on the photosensitive material 5.

FIG. 4 is a view showing the outer appearance of the light source holding block 41. Since the light source holding blocks 42 and 43 have the same appearance, the description thereof will be omitted.

The light source holding block 41 has light emitting elements such as LEDs having the same number and the same color as the number of channels. Light beam irradiation holes 410-1, 410-2 ... 410-n (hereinafter,
Collectively referred to as "light beam irradiation hole 410". ) Is LE
It is a hole through which the light beam emitted by D passes toward the outside, and is arranged in a horizontal row. The light beam emitted by the LED corresponding to channel 1 is emitted from the light beam irradiation hole 410-
The light beam that has passed through 1 and is emitted to the outside and is emitted by the LED corresponding to the channel n is the light beam emitting hole 410-.
It passes through n and is irradiated to the outside.

The light amount of the light beam emitted from each channel with respect to the same desired density is adjusted at the start of exposure so as to be constant. However, as shown in FIG. 11A, the light beams emitted from the channels at both ends of the channel 1 and the channel n do not have one adjacent channel. Therefore, the light amount of the light beam received from the peripheral portions 101-1 and 101-n of the channel on both ends of the photosensitive material 5 is smaller than the light amount of the light beam received from the central portion of the channel.

Further, when there is a beam pitch error or the like of the light beam irradiation hole 410 due to manufacturing variations that occur when the light source holding blocks 41, 42, and 43 are assembled in a factory, the light amount characteristics are changed by the individual optical units 23. . The beam pitch is the light beam irradiation hole 410-
The length from the center of 1 to the center of the light beam irradiation hole 410-n. As described above, the change in the optical characteristics of the light beam emitted from the optical unit 23 causes image unevenness in the image formed on the photosensitive material 5.

Further, the density of the image formed on both ends of the storage area of the photosensitive material 5 may change due to the difference in material characteristics of the photosensitive material 5 as shown in FIG. As a result, density unevenness occurs in the image formed on the photosensitive material 5,
The image is of poor quality.

Therefore, in order to solve these problems,
Based on the material characteristic of the photosensitive material 5 and the correction value obtained from the beam pitch characteristic of the light beam emitted from the optical unit 23, a process of adjusting the light amount of the light beam emitted from the channels at both ends is performed. The light amount correction process for adjusting the light amount of the light beam emitted from the channels on both ends will be described below.

FIG. 5 is a block diagram showing the electrical construction of the image forming apparatus 100. In FIG. 5, the control unit 70
0 is a CPU 600, a RAM 601, and a ROM 602
(Storage means), and I / O ports 603 and 604
Connected to sensors and actuators via
The actuator group is controlled based on the information from the sensors.

The RAM 601 stores initial values peculiar to the image forming apparatus 100. ROM 60 as a storage means
2, data for initializing various devices of the image forming apparatus 100, a light quantity correction table for each material 800, a target light quantity correction table 801, and a light quantity correction table for each channel (hereinafter referred to as “CH light quantity correction table”). ) 80
2. A light amount correction program 803, which is an exposure control unit, is stored. Details of the contents stored in the ROM 602 will be described later.

As sensors, the accumulation closing sensor S6
0, accumulation open sensor S61, paper feed shutter open sensor S62, cartridge presence sensor S63, paper end sensor S64, cover close detection sensor S65, cover lock detection sensor S66, paper feed roller crimp position detection sensor S67, paper feed roller release position A detection sensor S68, a drum feed / discharge roller press-contact position detection sensor S69, a drum feed / discharge roller release position detection sensor S70, a paper leading end reference position sensor S71, a paper feed amount detection sensor S72,
Paper end detection sensor S73, peeling claw release sensor S
74, peeling claw intermediate sensor S75, peeling claw pressure sensor S7
6, paper exit sensor S77, peeling jam detection sensor S78, cutter home position detection sensor S79,
A cutter end position detection sensor S80, an outlet shutter open detection sensor S81, a sub-scanning reference position detection sensor S82, a sub-scanning writing position detection sensor S83, and a sub-scanning overrun position detection sensor S84 are installed.

As the actuator group, an accumulation opening / closing motor M60, a paper feed shutter motor M61, a cover lock motor M62, a paper feed roller pressure release motor M63,
Paper feed motor M64, drum feed / discharge roller pressure release motor M65, drum feed / discharge motor M66, drum rotation motor M67, peeling pawl motor M68, exit shutter motor M
69, a carry-out motor M70, a sub-scanning motor M71, and a cutter motor M72 are installed, and a driver D60,
D61, D62, D63, D64, D65, D66, D
Drive control is performed by 67, D68, D69, D70, D71, D72 and D73.

The liquid crystal panel 63 is controlled by the driver D74 and displays the operating state of the image forming apparatus 100 and the like. On the touch panel 62, the user inputs various settings. The input content is output to the CPU 600 as digital data via the A / D conversion unit 64.

Digital image information is input from the RIP 65, and via the image data I / F unit 605, Y data buffer 608Y, M data buffer 608M, C data buffer 608C and BK data buffer 608BK (hereinafter collectively referred to as "data buffer"). 608 ”).

On the other hand, the rotary encoder 60 outputs a signal based on the feed information of the photosensitive material 5 to the PLL 606. The dot clock generation unit 607 outputs the dot clock signal to the LUT (look-up table) 609 in synchronization with the output signal of the PLL 606. LUT609 is
The data buffer 608 is synchronized with the dot clock signal.
The digital image signal input from is converted into RGB and D
/ A converters 610R, 610G and 610B (hereinafter,
Comprehensively referred to as "D / A converter 610". ). The D / A conversion unit 610 performs digital-to-analog conversion of the image signal and outputs the converted image signal to the driver D611.
It is output to R, D611G, and D611B (hereinafter collectively referred to as "driver D611"). Driver D6
Reference numeral 11 drives the LEDs included in the light source holding blocks 41, 42 and 43.

FIG. 6 is a partial excerpt of the block diagram of the image forming apparatus 100 of FIG. The operation of the light amount correction process will be described with reference to FIG.

First, the CPU 600 loads the light amount correction program 803 stored in the ROM 602 into the RAM 801.
And execute the program.

The LUT 609 converts the digital image data input from the data buffer 608 into RGB digital image data, and converts the converted digital image data into a CPU.
Output to 600. The CPU 600 uses the material-specific light amount correction table 800, the target light amount correction table 801, and the CH.
The input digital image data is corrected based on the data of each light amount correction table 802.

Then, the CPU 600 outputs the corrected digital image data to the LUT 609. LUT609
Outputs digital image data to the D / A conversion unit 610, and digital-to-analog conversion is performed. The converted image data is output to the driver D611, and the driver D611 uses the light source holding block 4 based on the image data.
It drives the LEDs contained in 1, 42 and 43.

FIG. 7 is a diagram showing the data structure of the light quantity correction table 800 for each material. The light quantity correction table 800 for each material is a data table in which the light quantity correction values of the light beams of both channels are set based on a beam pitch error caused by manufacturing variations of the light source holding units 41, 42, and 43. The light amount correction table 800 for each material is set for each material characteristic of the photosensitive material 5. For example, for the material A, the light amount correction table for each material 800-
1. Material-specific light amount correction table 800-
2. Material-specific light amount correction table 800-3 for material C
Is set.

Here, for example, when the beam pitch error of the light source holding block 41 is +3 [μm], the photosensitive material 5 of the material A is
When forming an image on the sheet, the light amount correction table for each material 800-
The light amount correction value for each material of the light amount of the light beam emitted from the channels on both sides of 1 is set to 80%. This is because the beam pitch is expanded by +3 [μm] as compared with the normal beam pitch, and therefore, in the photosensitive material 5, the edge of the n-th recording area and the edges of the (n-1) -th and n + 1-th recording areas are formed. Overlap. For this reason, the color density of the image becomes high in the portion where the exposure is overlapped, and uneven density of the image occurs. Therefore, when the beam pitch is wider than the normal value, the light amount of the light beam emitted from the channels at both ends is reduced.

On the other hand, in FIG. 7, the image forming apparatus 100
When the beam pitch error of -3 [μm] is used to form an image on the photosensitive material 5 of the material a, the light amount correction table 800-1 for each material indicates the light amount of the light beam emitted from the channels at both ends by the material. The light amount correction value is set to 110%.
This is because the beam pitch is-compared to the normal beam pitch.
Since it is narrowed by about 3 [μm], in the photosensitive material 5, there is an unexposed portion or a portion with a significantly small exposure amount between the n-th recording area and the (n-1) th and (n + 1) th recording areas. It occurs in the main scanning direction. As a result, the color density of the image becomes lighter in the portion that is less exposed, and uneven density of the image occurs. Therefore, when the beam pitch is narrower than the normal value, the light amount of the light beam emitted from the channels at both ends is increased.

The data of the light quantity correction table 800 for each material is obtained by measuring the characteristics of the light beam emitted from the optical unit 23 at the time of assembling the image forming apparatus 100 at the factory and determining the type of the photosensitive material 5 used in the image forming apparatus 100. To R in advance
It is stored in the OM 602.

FIG. 8 shows the data structure of the target light amount correction table 801. Target light amount correction table 80
Reference numeral 1 is a data table in which a correction value for the light quantity of the light beam (hereinafter referred to as "target light quantity") necessary for obtaining a desired density in the image formed on the photosensitive material 5 is set. In the photosensitive material 5, the appearance of image unevenness may differ depending on the density due to the difference in material characteristics. In order to deal with such a problem, the light quantity of the light beam is corrected according to the desired density based on the data of the target light quantity correction table 801. The target light amount correction table 801 is for the photosensitive material 5
The material properties of and set based on the measured values,
The ROM 60 is preliminarily used when the image forming apparatus 100 is assembled in the factory.
Stored in 2.

FIG. 9 is a view showing the data structure of the CH-specific light amount correction table 802. The CH-by-CH light amount correction table 802 is a table that stores the correction value of the target light amount of the light beam emitted from each channel. In the CH-based light intensity correction table 802, the data set in the table is created during execution of the light intensity correction program 803. The method of setting the data will be described later.

FIG. 10 is a flow chart showing the operation of the light amount correction processing. First, the CPU 600 sets the photosensitive material 5
In accordance with the material type of No. 2, one of the light quantity correction tables 800-1, 800-2 and 800-3 for each material is read from the ROM 602 and stored in the RAM 601 (step A1). For the material type of the photosensitive material 5, for example, when the user sets the photosensitive material 5 in the paper loading unit 1, material type data for distinguishing the material type is input from the touch panel 62. Alternatively, the user may input from the touch panel 62 when the light amount correction program 803 is executed. The input material type data is stored in the RAM 601 and the CPU 600 stores the data in the RAM in step A1.
By reading from the AM 601, the light amount correction data for each material 800 corresponding to the material type is selected and read.

Here, for example, when the material A is used as the photosensitive material 5, the CPU 600 reads the light quantity correction table 800-1 for each material. And the beam pitch error is +
At 3 [μm], the CPU 600 sets 80% as the light amount correction value for each material and stores it in the RAM 601.

Next, the CPU 600 reads the target light amount correction table 801 from the ROM 602, and the RAM 601.
(Step A2). And the CPU 600
The LUT 609 inputs the digital image data from the data buffer 608, inputs the target light amount determined by converting into RGB, and sets the target light amount correction value.

For example, when the target light amount determined by the LUT 609 is 110%, the CPU 600 sets 95% as the target light amount correction value from the target light amount correction table 801, and RA
Store in M601.

Subsequently, the CPU 600 sets the data of the CH-specific light quantity correction table 802 according to the material-specific light quantity correction value and the target light quantity correction value obtained in step A1 and step A2 (step A3). First, since the target light amount correction value is 95%, the CPU 600 sets the target light amount to 95% for all channels. Further, since the light quantity correction value for each material is 80%, the target light quantity of the channels 1 and n, which are the channels at both ends, is 95% × 80%.
= 76%.

Then, the CPU 600 corrects the digital image data input from the LUT 609 based on the correction value of the CH-specific light amount correction table 802, and outputs the corrected digital image data to the LUT 609 (step A4). Then, the process ends.

As described above, the light quantity correction table 800 for each material is set based on the material characteristics of the photosensitive material 5 and the manufacturing variations of the light source holding blocks 41, 42 and 43, and the light quantity correction program 803 is executed to execute the light quantity correction for each CH. A correction table 802 is created. Then, the light amount of the light beam of each channel is corrected based on the data of the table to adjust the light amount of the light beam emitted from the channels at both ends. Accordingly, it is possible to reduce image unevenness when an image is formed on the photosensitive material 5.

Further, when the density of the formed image is different due to the difference in the material characteristics of the photosensitive material 5 and the appearance of the image unevenness is different due to the difference in the density, each channel of each channel is determined based on the data of the target light amount correction table 801. The light amount of the light beam is corrected, and the light amount is adjusted so that a desired density can be obtained by exposure. Accordingly, it is possible to reduce image unevenness when an image is formed on the photosensitive material 5.

The data of the light quantity correction table for each material 800 has been described as being fixedly set at the time of factory shipment, but the data content is arbitrarily changed by the user inputting the data from the touch panel 62 or the like. It may be possible. Alternatively, although not shown, by installing a communication unit capable of data communication with an external device in the image forming apparatus 100, a new material can be sent from the external device to the communication unit of the image forming apparatus 100 via a network or the like. It is also possible to send the light quantity correction table. And
The new light amount correction table for each material received by the CPU 600 and the data of the light amount correction table for each material 800 stored in the ROM 802 are changed. As a result, even when using the photosensitive material 5 having material characteristics that are not set in the material-specific light quantity correction table 800, the light quantity correction processing is performed by newly inputting a correction value based on the material characteristics from the outside. You can

Further, for example, the photosensitive material 5 may be exposed to cyan and / or magenta hues other than yellow, and the light amount correction processing may be performed only on the LEDs forming the light beams emitted from the channels at both ends. .

This is because the image unevenness due to yellow on the photosensitive material 5 is almost invisible to the human eye. Therefore, the light amount correction processing of the light beam for exposing the yellow hue of the photosensitive material 5 is not performed, and the channels at both ends are not processed. In the above, it can be realized by performing the light amount correction process for the corresponding LED only when the light beam for exposing the cyan and / or magenta hue of the photosensitive material 5 is irradiated. Accordingly, the light amount correction process can be performed quickly and easily.

[0082]

According to the invention described in claim 1, of the light sources of the light source means, by correcting the light sources at one end and the other end based on the light amount correction data, the light amounts of the light sources at the one end and the other end are corrected. Can be adjusted. Therefore, when the photosensitive recording medium is exposed by using the light source means to form an image, the amount of exposure of the recording medium by the light sources at one end and the other end can be adjusted. As a result, it is possible to reduce image unevenness that has occurred due to a decrease in the amount of exposure of the recording medium by the light sources at one end and the other end.

According to the second aspect of the invention, the value of the light quantity correction data can be changed by using the data value changing means for changing the value of the light quantity correction data. Thereby, the adjustment amount of the light amount of the light source at the one end and the other end of the light source means can be arbitrarily set.

According to the third aspect of the present invention, the light amount correction data is stored in the storage means for each characteristic of the recording medium, and one end of the light source means and the other end of the light source means are stored based on the light amount correction data corresponding to the characteristic of the recording medium used. By adjusting the light amount of the light source at the end, the exposure amount of the light sources at the one end and the other end to the recording medium can be adjusted according to the characteristics of the recording medium. As a result, it is possible to reduce image unevenness that has occurred due to a decrease in the amount of exposure of the recording medium by the light sources at one end and the other end.

According to the fourth aspect of the present invention, the light amount correction data is stored in the storage medium for each arrangement condition of the light source of the light source means, and the light amount correction data is stored based on the light amount correction data corresponding to the arrangement condition of the light source means to be used. By adjusting the light amount of the light source at one end and the other end of the light source means, the exposure amount to the recording medium by the light source at the one end and the other end can be adjusted according to the difference in the arrangement condition of the light sources. As a result, it is possible to reduce image unevenness that has occurred due to a decrease in the amount of exposure of the recording medium by the light sources at one end and the other end.

According to the fifth aspect of the invention, each light emitting element is corrected to a desired light amount based on the light amount correction data of a plurality of light emitting elements of different colors forming the light sources at one end and the other end of the light source means. By doing so, the amount of light at one end and the other end can be adjusted. As a result, it is possible to reduce image unevenness that has occurred due to a decrease in the amount of exposure of the recording medium by the light sources at one end and the other end.

According to the sixth aspect of the invention, even when the density of the image formed on the recording medium differs due to the difference in material characteristics or the demand of the user of the apparatus, the light amount at one end and the other end can be changed according to the desired density. Can be adjusted. Accordingly, it is possible to reduce image unevenness of the image formed on the recording medium.

According to the seventh aspect of the invention, in image formation on the recording medium by exposure of the image forming apparatus, it is difficult for human beings to visually recognize image unevenness due to yellow. Therefore, it is difficult to distinguish cyan and / or magenta hues. The light amount is corrected only for the light emitting elements that constitute the light sources at one end and the other end that emit the light beam for exposure. As a result, the light amount can be corrected more quickly than the light amount correction is performed for all the light emitting elements forming the light sources at the one end and the other end.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an image forming apparatus.

FIG. 2 is a perspective view of a drum and an optical unit of the image forming apparatus.

FIG. 3 is a diagram showing a configuration of an optical unit.

FIG. 4 is a diagram showing an appearance of a light source holding block.

FIG. 5 is a block diagram showing a configuration of an image forming apparatus.

FIG. 6 is a diagram in which a block diagram of an image forming apparatus is partially extracted.

FIG. 7 is a diagram showing a data configuration of a light amount correction table for each material.

FIG. 8 is a diagram showing a data configuration of a target light amount correction table.

FIG. 9 is a diagram showing a data structure of a CH-specific light amount correction table.

FIG. 10 is a flowchart showing the operation of light amount correction processing.

FIG. 11 is a diagram showing a light amount of a light beam emitted from an optical unit and a color density at the time of exposure by the light amount.

FIG. 12 is a diagram showing material characteristics of a photosensitive material.

[Explanation of symbols]

1 Paper loading section 2 Exposure unit 21 Paper feeder 22 drums 23 Optical unit 41 ・ 42 ・ 43 Light source holding block 44 mirror 45/46 dichroic mirror 47 lens 24 Accumulation part 25 Paper output section 3 Development unit 4 Paper output section 600 CPU 601 RAM 602 ROM 800 Light intensity correction table for each material 801 Target light intensity correction table 802 CH light intensity correction table 803 Light intensity correction program

Continued front page    F-term (reference) 2C162 AE12 AE23 AE28 AE48 AE77                       AF13 AF20 FA04 FA17 FA18                       FA34 FA49                 2H106 AA41 AA47 AA76 AA85                 2H110 AA01 CD12 CD17 CD18

Claims (7)

[Claims] 1. A photosensitizer comprising: a light source means having a plurality of light sources arranged in a row; and an exposure control means for controlling the light quantity of each of the light sources. An image forming apparatus for forming an image while exposing a flexible recording medium to a predetermined width, further comprising storage means for storing light amount correction data of light sources at one end and the other end of the plurality of light sources of the light source means. The exposure control means corrects a desired light quantity for the light sources at the one end and the other end based on the light quantity correction data stored in the storage means, and controls the light quantity of the light sources at the one end and the other end. An image forming apparatus characterized by. 2. The image forming apparatus according to claim 1, further comprising a data value changing unit that changes the light amount correction data stored in the storage unit. 3. The image forming apparatus according to claim 1, wherein the storage unit sets a plurality of types of the recording medium and light amount correction data set based on characteristics of the recording medium of each type. And a selection means for selecting one of a plurality of types of the recording medium stored in the storage means, wherein the exposure control means is for the recording medium selected by the selection means. An image forming apparatus, wherein the correction is performed based on light amount correction data corresponding to a type. 4. The image forming apparatus according to claim 1, wherein the storage unit stores a plurality of light amount correction data according to an arrangement condition of a light source included in the light source unit, and the light amount correction data is stored in the storage unit. Of the multiple light intensity correction data
The image forming apparatus further comprises a selection unit that selects one light amount correction data, and the exposure control unit performs the correction based on the light amount correction data selected by the selection unit. 5. The image forming apparatus according to claim 1, wherein each of the light sources has a plurality of light emitting elements, and the storage means has a plurality of light sources included in the light source means. Storing the light amount correction data of each light emitting element of the light source at one end and the other end, the exposure control means, a desired light amount for each light emitting element of the light source at the one end and the other end, stored in the storage means, An image forming apparatus which controls each light emitting element of the light source at the one end and the other end by performing correction based on the light amount correction data of the corresponding light emitting element. 6. The image forming apparatus according to claim 1, wherein the storage unit further stores target light amount correction data set according to a desired density of an image formed on the recording medium. The exposure control unit corrects a desired light amount for the light sources at the one end and the other end based on the target light amount correction data stored in the storage unit to control the light sources at the one end and the other end. A characteristic image forming apparatus. 7. The image forming apparatus according to claim 1, wherein the recording medium emits a light beam from each of the light sources to develop a color image in each of cyan, magenta, and yellow. In the image forming apparatus, the exposure control unit determines whether or not the light beams of the light sources at the one end and the other end correspond to cyan and / or magenta which are colored by the recording medium. An image forming apparatus, which has a means and performs the correction when it corresponds to cyan and / or magenta.