JP2011081078A - Image writing apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce density unevenness by a simple method in comparison with a case not performing setting based on distribution information in an image writing apparatus having a plurality of light emitting elements. <P>SOLUTION: The image writing apparatus (LHy) includes: writing members (1-3) having a plurality of light emitting elements and writing a latent image on an image support material (Py) surface; a distribution information acquisition means (C4C) obtaining distribution information to identify a light volume distribution (6) of the light emitting elements previously measured for each of the writing members (1-3); a correction information setting means (C4F) setting correction information (7) to equalize image density written in the writing members (1-3) based on the distribution information (6); and a writing control means (C6) operating the writing members (1-3) to control writing of the latent image based on the correction information (7) set by the correction information setting means (C4F). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image writing apparatus and an image forming apparatus.

  For image forming apparatuses for writing images in image forming apparatuses such as copying machines and printers, techniques described in the following Patent Documents 1 to 5 are conventionally known.

  In Japanese Patent Application Laid-Open No. 10-811 as Patent Document 1, every other light emitting element is caused to emit light or every four light emitting elements are emitted to a print head (30a-30c) in which light emitting elements are arranged in an array. The image printed on the photographic paper is read with a densitometer, and the correction amount between the reference exposure amount, which is the average value of the exposure amount data of all the elements, and the exposure amount of each element is calculated for each light emitting element. A technique for correcting variations in exposure amount using a correction amount during image formation is described.

  In Japanese Patent Laid-Open No. 2002-307745 as Patent Document 2, a test image is formed at the time of shipment or maintenance in order to correct variations in the amount of light in the main scanning direction of the exposure light emitted from the LED array (32). Then, the formed test image is read by the image reading unit (10), the LED chip (32a) that needs to be corrected in the LED array (32) is specified from the acquired density data, and the LED chip (32a) is identified. ) Is a technique for correcting the amount of exposure light.

  Japanese Patent Application Laid-Open No. 2004-338367 as Patent Document 3 discloses that after a correction image is printed on photographic paper 2 in order to perform light amount correction corresponding to each recording element in a print head in which recording elements are arranged, A technique is described in which density measurement is performed by an image reading device (70) and a correction amount for each recording element is obtained from the obtained density.

  In Japanese Patent Application Laid-Open No. 2008-90209 as Patent Document 4, the adjustment pins (112, 113) protruding from both ends in the main scanning direction of the LED head (100) hit the positioning portion (26) of the image forming apparatus (10). In the configuration in which the LED head (100) is positioned, the amount of protrusion of the adjustment pins (112, 113) is adjusted in accordance with the variation in the maximum focal position, so that the LED head (100) is moved with respect to the main scanning direction. A technique for tilting and suppressing variation in focal position is described.

  In Japanese Patent Application Laid-Open No. 9-1857 as Patent Document 5, the LED substrate (6) is held by the adjusting mechanism (8) in a state where the LED chip (12) is held in the shape of an elastically deformable LED substrate (6). A technique for adjusting the focus of each LED chip (12) so as to form an image on the photosensitive drum (2) by elastic deformation is described.

Japanese Patent Laid-Open No. 10-811 ("0029" to "0043", FIGS. 2 to 6) JP 2002-307745 A ("0025" to "0029") JP 2004-338367 A ("0209" to "0242") JP 2008-90209 A ("0028" to "0053", FIG. 3, FIG. 5 to FIG. 8) JP-A-9-1857 ("0015" to "0025", FIGS. 1 to 2)

  An object of the present invention is to suppress density unevenness by a simple method in an image writing apparatus having a plurality of light emitting elements, compared to a case where correction information is not set based on distribution information.

In order to solve the technical problem, an image writing device according to claim 1 is provided.
A writing member having a plurality of light emitting elements arranged in a direction to write a latent image, and writing the latent image on the surface of the image carrier;
Distribution information acquisition means for acquiring distribution information for specifying a light amount distribution of the light emitting element measured in advance for each writing member;
Correction information setting means for setting correction information for making the image density written by the writing member uniform based on distribution information;
A writing control means for controlling writing of a latent image by operating the writing member based on the correction information set by the correction information setting means;
It is provided with.

The invention according to claim 2 is the image writing apparatus according to claim 1,
A storage medium supported by the writing member and storing the distribution information;
The distribution information acquisition means for acquiring the distribution information stored in the storage medium;
It is provided with.

The invention according to claim 3 is the image writing apparatus according to claim 1 or 2,
An input unit that can be entered by the operator;
The distribution information acquisition means for acquiring the distribution information input from the input unit;
It is provided with.

According to a fourth aspect of the present invention, in the image writing apparatus according to any one of the first to third aspects,
Correction information storage means for storing correction information set in advance corresponding to the distribution information for each of the writing members;
The correction information setting means for setting the correction information corresponding to the distribution information acquired by the distribution information acquisition means from among the correction information stored in the correction information storage means;
It is provided with.

The invention according to claim 5 is the image writing apparatus according to any one of claims 1 to 3,
Correction information calculation means for calculating the correction information based on the distribution information acquired by the distribution information acquisition means;
The correction information setting means for setting the correction information calculated by the correction information calculation means;
It is provided with.

A sixth aspect of the present invention is the image writing apparatus according to any one of the first to fifth aspects,
The write control means for controlling the writing of the latent image by controlling the light amount of each light emitting element based on the correction information set by the correction information setting means;
It is provided with.

The invention according to claim 7 is the image writing apparatus according to claim 6,
Light amount control for controlling the light amount of the light emitting element based on the initial light amount control information, which is information for controlling the light amount of each light emitting element set in advance so as to be the light amount distribution of the light emitting element, and the correction information A light amount control calculating means for calculating information;
The writing control means for controlling writing of a latent image based on the light amount control information;
It is provided with.

The invention according to claim 8 is the image writing apparatus according to any one of claims 1 to 5,
The write control means for controlling the writing of the latent image by correcting the gradation of the image to be written based on the correction information set by the correction information setting means;
It is provided with.

The invention according to claim 9 is the image writing device according to any one of claims 1 to 8,
The writing member supported based on the light amount distribution and tilted along the sub-scanning direction of the image carrier so that the focal position of each light emitting element is on the surface of the image carrier;
It is provided with.

The invention according to claim 10 is the image writing apparatus according to claim 9, wherein
The writing member supported so as to be tiltable along a sub-scanning direction of the image carrier, with a rotation axis extending along a direction approaching and separating from the image carrier as a center.
It is provided with.

The invention according to claim 11 is the image writing apparatus according to claim 9 or 10, wherein
The photosensitive member surface is supported so as to be movable toward and away from the image carrier, and is positioned along the main scanning direction of the image carrier and the focal length of the writing member is maximum. The writing member supported in a state inclined from the state corresponding to the sub-scanning direction,
It is provided with.

The invention according to claim 12 is the image writing apparatus according to any one of claims 1 to 11,
A plurality of the writing members arranged along the main scanning direction of the image carrier,
It is provided with.

In order to solve the technical problem, an image forming apparatus according to claim 13 is provided.
An image carrier,
The image writing device according to any one of claims 1 to 12, wherein a latent image is formed on the surface of the image carrier.
A developing device for developing the latent image on the surface of the image carrier into a visible image;
A transfer device for finally transferring a visible image on the surface of the image carrier to a medium;
A fixing device for fixing the visible image transferred to the medium;
It is provided with.

According to the first aspect of the present invention, density unevenness can be suppressed by a simple method in an image writing apparatus having a plurality of light emitting elements, compared to a case where correction information is not set based on distribution information.
According to the second aspect of the present invention, the correction information can be automatically set based on the distribution information supported by the writing member and stored in the storage medium.
According to the third aspect of the present invention, the correction information can be automatically set based on the distribution information input from the input unit.
According to the fourth aspect of the present invention, correction information can be retrieved from correction information stored in advance and automatically set.

According to the invention described in claim 5, the correction information can be automatically calculated from the distribution information, and the calculated correction information can be set.
According to the sixth aspect of the present invention, image processing is not necessary as compared with the case where the amount of light is not controlled, and unevenness can be suppressed without changing the settings of members other than the image writing apparatus.
According to the seventh aspect of the present invention, the light amount control information of the light emitting element can be corrected.
According to the eighth aspect of the invention, it is possible to perform gradation correction based on the correction information and suppress density unevenness.
According to the ninth aspect of the present invention, density unevenness can be suppressed by a simple method as compared with the case where the writing member is not inclined.

According to the tenth aspect of the present invention, density unevenness can be suppressed by a simple method of inclining the writing member around the rotation axis.
According to the eleventh aspect of the present invention, it is possible to suppress unevenness in the light amount distribution based on the maximum position.
According to the twelfth aspect of the present invention, in the image writing apparatus capable of writing an image that is long in the main scanning direction, density unevenness can be suppressed by a simple method.
According to the invention described in claim 13, compared to a case where correction information is not set based on distribution information, in an image writing apparatus having a plurality of light emitting elements, density unevenness can be suppressed by a simple method, Image quality can be improved.

FIG. 1 is an overall explanatory view of an image forming apparatus according to Embodiment 1 of the present invention. FIG. 2 is an explanatory diagram of a visible image forming member of Example 1. FIG. 3 is an explanatory diagram of the image writing apparatus according to the first embodiment. FIG. 4 is a block diagram illustrating the functions of the control unit of the image forming apparatus according to the first embodiment. FIG. 5 is an explanatory diagram of a focus profile according to the first embodiment. FIG. 6 is an explanatory diagram of a correction table according to the first embodiment, FIG. 6A is an explanatory diagram of a correction table set corresponding to a convex focus profile having a large focal deflection amount, and FIG. 6B is a small focal deflection amount. FIG. 6C is an explanatory diagram of a correction table set in correspondence with a concave focus profile having a large focal deflection amount. FIG. 6C is an explanatory diagram of a correction table set in correspondence with a convex focus profile. FIG. 7 is an explanatory diagram of an example of gradation correction according to the first embodiment. FIG. 7A is an explanatory diagram before gradation correction, and FIG. 7B is an explanatory diagram after gradation correction. FIG. 8 is a flowchart of density unevenness adjustment processing according to the first embodiment of the present invention. FIG. 9 is a block diagram of the second embodiment and corresponds to FIG. 4 of the first embodiment. FIG. 10 is an explanatory diagram of adjustment information according to the first embodiment, FIG. 10A is an explanatory diagram of a waveform focus profile, and FIG. 10B is an explanatory diagram of a convex focus profile. FIG. 11 is a flowchart of density unevenness adjustment processing according to the second embodiment of the present invention. FIG. 12 is a block diagram of the third embodiment and corresponds to FIG. 4 of the first embodiment. FIG. 13 is an explanatory diagram of density unevenness adjustment according to the third embodiment. FIG. 13A is an explanatory diagram of the relationship between the initial light amount control information and the correction table. FIG. 13B is a state in which the light amount control information is calculated based on the correction table. It is explanatory drawing. FIG. 14 is a flowchart of density unevenness adjustment processing according to the third embodiment of the present invention. FIG. 15 is an explanatory diagram of a main part of the latent image forming apparatus according to the fourth embodiment. FIG. 16 is an explanatory diagram of the density unevenness adjusting method of the fourth embodiment, and is an explanatory diagram of an alignment process. FIG. 17 is an explanatory view of the density unevenness adjusting method of the fourth embodiment, and is an explanatory view of the inclination matching step. 18A and 18B are explanatory diagrams of a calculation method of the inclination angle in the density unevenness adjustment method of the fourth embodiment. FIG. 18A is a plan view and FIG. 18B is a side view. FIG. 19 is an explanatory diagram of a conventional density unevenness correction method described in Patent Document 4. 20A and 20B are explanatory diagrams of changes in the focus profile in the density unevenness correction method of the prior art shown in FIG. 19, FIG. 20A is an explanatory diagram when moved in parallel, and FIG. 20B is a case when tilted with respect to the main scanning direction. It is explanatory drawing of. FIG. 21 is an explanatory diagram of a modification of the fourth embodiment.

Next, specific examples of embodiments of the present invention (hereinafter referred to as examples) will be described with reference to the drawings, but the present invention is not limited to the following examples.
In order to facilitate understanding of the following description, in the drawings, the front-rear direction is the X-axis direction, the left-right direction is the Y-axis direction, the up-down direction is the Z-axis direction, and arrows X, -X, Y, -Y, The directions indicated by Z and -Z or the indicated side are defined as front, rear, right, left, upper, lower, or front, rear, right, left, upper, and lower, respectively.
In the figure, “•” in “○” means an arrow pointing from the back of the page to the front, and “×” in “○” is the front of the page. It means an arrow pointing from the back to the back.
In the following description using the drawings, illustrations other than members necessary for the description are omitted as appropriate for easy understanding.

FIG. 1 is an overall explanatory view of an image forming apparatus according to Embodiment 1 of the present invention.
In FIG. 1, an image forming apparatus U includes a user interface UI as an example of an input unit, an image input apparatus U1 as an example of an image information input apparatus, a paper feeding apparatus U2, an image forming apparatus main body U3, and a paper processing apparatus U4. Have.

The user interface UI includes a display panel UI0 as an example of a display unit, a plurality of input buttons, and the like.
The image input device U1 includes an automatic document feeder U1a and an image scanner U1b as an example of an image reading unit. In FIG. 1, an image input apparatus U1 reads a document (not shown), converts it into image information, and inputs it to the image forming apparatus body U3.
The sheet feeding device U2 takes out the sheet feeding trays TR1 to TR4 as an example of a plurality of medium accommodating units and the recording sheet S as an example of a medium accommodated in each of the sheet feeding trays TR1 to TR4, and main body of the image forming apparatus. A sheet feeding path SH1 and the like for conveying to U3 are provided.

In FIG. 1, an image forming apparatus main body U3 includes an image recording unit U3a that records an image on a recording sheet S conveyed from the sheet feeding device U2, a toner dispenser device U3b as an example of a developer supply device, and a conveyance path. As an example, a sheet conveyance path SH2, a sheet discharge path SH3, a sheet reversing path SH4, a sheet circulation path SH6, and the like are provided. The image recording unit U3a will be described later.
The image forming apparatus body U3 is controlled by a controller C as an example of a control unit, a laser drive circuit D as an example of a latent image writing device drive circuit controlled by the controller C, and the controller C. A power supply circuit E and the like are included.

The laser drive circuit D, the operation of which is controlled by the controller C, presets the laser drive signals corresponding to the image information of Y: yellow, M: magenta, C: cyan, K: black inputted from the image input device U1. At this time, the image is output to the latent image forming devices LHy, LHm, LHc, and LHk of each color as an example of the image writing device.
Below the latent image forming apparatuses LHy, LHm, LHc, and LHk of the respective colors, a drawing member U3c for an image forming unit is drawn out to the front of the image forming apparatus main body U3 by a pair of left and right guide members R1 and R1. It is supported so as to be movable between the position and the mounting position mounted inside the image forming apparatus main body U3.

FIG. 2 is an explanatory diagram of a visible image forming member of Example 1.
1 and 2, the K-color image carrier unit Uk includes a photosensitive member Pk, a charger CCk as an example of a discharger, and a cleaner CLk as an example of an image carrier cleaner. The other color Y, M, and C image carrier units Uy, Um, and Uc are also photoconductors Py, Pm, and Pc, chargers CCy, CCm, CCc, and cleaners CLy, CLm, as an example of the image carrier. CLc. In Example 1, the K photoconductor Pk, which is frequently used and has a lot of surface wear, has a larger diameter than the other photoconductors Py, Pm, and Pc, and is capable of high-speed rotation and has a long service life. Has been changed.
Visible image forming members Uy + Gy, Um + Gm, Uc + Gc, Uk + Gk are constituted by the image carrier units Uy, Um, Uc, Uk and developing devices Gy, Gm, Gc, Gk having a developing roll R0. The image holding unit Uy, Um, Uc, Uk and developing devices Gy, Gm, Gc, Gk are detachably mounted on the drawing member U3c for the image forming unit.

  In FIG. 1, photoconductors Py, Pm, Pc, and Pk are uniformly charged by chargers CCy, CCm, CCc, and CCk, respectively, and then output from the latent image forming devices LHy, LHm, LHc, and LHk. An electrostatic latent image is formed on the surface of the writing light. The electrostatic latent images on the surfaces of the photoreceptors Py, Pm, Pc, and Pk are visualized images of Y: yellow, M: magenta, C: cyan, and K: black by developing units Gy, Gm, Gc, and Gk. The toner image is developed as an example.

The toner images on the surfaces of the photoreceptors Py, Pm, Pc, and Pk are transferred to the intermediate transfer member in primary transfer regions Q3y, Q3m, Q3c, and Q3k by primary transfer rolls T1y, T1m, T1c, and T1k as an example of a primary transfer unit. As an example, the images are sequentially transferred onto an intermediate transfer belt B, and a multicolor image, that is, a so-called color image is formed on the intermediate transfer belt B. The color image formed on the intermediate transfer belt B is conveyed to a secondary transfer area Q4 as an example of an image recording area.
In the case of only black image data, only K: black photoconductor Pk and developing unit Gk are used, and only a black toner image is formed.
After the primary transfer, residual toner on the surface of the photoreceptors Py, Pm, Pc, and Pk is cleaned by the image carrier cleaners CLy, CLm, CLc, and CLk.

Below the drawing member U3c for the image forming unit, a drawing position where the drawing member U3d for the intermediate transfer member is drawn to the front of the image forming apparatus body U3, and a mounting position where the drawing member U3d is mounted inside the image forming apparatus body U3. Is supported so as to be movable between. Due to the intermediate transfer member pull-out member U3d, the belt module BM as an example of an intermediate transfer device comes into contact with the lower surface of the photoconductors Py, Pm, Pc, Pk, and the lower position away from the lower surface. It is supported so that it can move up and down.
The belt module BM includes the intermediate transfer belt B, belt support rolls Rd, Rt, Rw, Rf, T2a as examples of intermediate transfer member support members, and the primary transfer rolls T1y, T1m, T1c, T1k. Have. Belt support rolls Rd, Rt, Rw, Rf, and T2a are a belt drive roll Rd as an example of an intermediate transfer drive member, a tension roll Rt as an example of a tension applying member, a walking roll Rw as an example of a meandering prevention member, and a follower It has a plurality of idler rolls Rf as an example of members and a backup roll T2a as an example of a secondary transfer counter member. The intermediate transfer belt B is supported by the belt support rolls Rd, Rt, Rw, Rf, T2a so as to be rotatable in the direction of the arrow Ya.

A secondary transfer unit Ut is disposed below the backup roll T2a. A secondary transfer roll T2b as an example of a secondary transfer member of the secondary transfer unit Ut is disposed so as to be separated from and contactable with the backup roll T2a with the intermediate transfer belt B interposed therebetween. The secondary transfer roll T2b is A secondary transfer area Q4 as an example of an image recording area is formed by the area in contact with the intermediate transfer belt B. Further, a contact roll T2c as an example of a voltage application member is in contact with the backup roll T2a, and a secondary transfer device T2 is constituted by the rolls T2a to T2c.
A secondary transfer voltage having the same polarity as the toner charging polarity is applied to the contact roll T2c from the power supply circuit controlled by the controller C at a predetermined timing.

A sheet conveyance path SH2 as an example of a conveyance path is disposed below the belt module BM. The recording sheet S fed from the sheet feeding device U2 is conveyed from the sheet feeding path SH1 to the sheet conveying path SH2 by a conveyance roll Ra as an example of a conveyance member. Then, by the registration roll Rr as an example of the conveyance timing adjusting member and an example of the downstream end aligning member, the medium guide member SGr, the pre-transfer, and the toner image are conveyed to the secondary transfer region Q4 in time. It is conveyed to the secondary transfer region Q4 through the medium guide member SG1.
The medium guide member SGr is fixed to the image forming apparatus main body U3 together with the registration roll Rr.
The toner image on the intermediate transfer belt B is transferred to the recording sheet S by the secondary transfer device T2 when passing through the secondary transfer region Q4. Note that in the case of a full-color image, the toner images primarily transferred onto the surface of the intermediate transfer belt B are secondarily transferred onto the recording sheet S at once.

The intermediate transfer belt B after the secondary transfer is cleaned, that is, cleaned by a belt cleaner CLB as an example of an intermediate transfer body cleaner. The secondary transfer roll T2b and the belt cleaner CLB are supported so as to be separated from and in contact with the intermediate transfer belt B.
The primary transfer rolls T1y, T1m, T1c, T1k, the intermediate transfer belt B, the secondary transfer unit T2, the belt cleaner CLB, and the like constitute a transfer device T1 + B + T2 + CLB that transfers the image on the surface of the photoreceptors Py to Pk to the recording sheet S. Has been.
The visible image forming member Uy + Gy to Uk + Gk and the transfer device T1 + B + T2 + CLB constitute an image recording unit U3a of Example 1.

The recording sheet S on which the toner image has been secondarily transferred is conveyed to the fixing device F through a post-transfer medium guide member SG2 and a sheet conveyance belt BH as an example of a medium conveyance member before fixing. The fixing device F has a heating roll Fh as an example of a heat fixing member and a pressure roll Fp as an example of a pressure fixing member, and is fixed by a region where the heating roll Fh and the pressure roll Fp are in pressure contact with each other. Region Q5 is formed.
The toner image on the recording sheet S is heated and fixed by the fixing device F when passing through the fixing region Q5. A transport path switching member GT1 is provided on the downstream side of the fixing device F. The conveyance path switching member GT1 selectively switches the recording sheet S conveyed in the sheet conveyance path SH2 and heated and fixed in the fixing region Q5 to either the sheet discharge path SH3 or the sheet reversal path SH4. The sheet S conveyed to the sheet discharge path SH3 is conveyed to the sheet conveyance path SH5 of the sheet processing apparatus U4.

  A curl correction device U4a is disposed in the middle of the sheet conveyance path SH5, and a switching gate G4 as an example of a conveyance path switching member is disposed in the sheet conveyance path SH5. The switching gate G4 causes the recording sheet S conveyed from the sheet conveying path SH3 of the image forming apparatus main body U3 to be curved, so-called curl direction, depending on the first curl correction member h1 or the second curl correction member h2. Transport to either side of The recording sheet S conveyed to the first curl correction member h1 or the second curl correction member h2 is curled when passing. The recording sheet S with the curl corrected is in a so-called face-up state in which the image fixing surface of the sheet is directed upward from a discharge roll Rh as an example of a discharge member to a discharge tray TH1 as an example of a discharge unit of the paper processing device U4. It is discharged at.

The recording sheet S conveyed to the sheet reversing path SH4 side of the image forming apparatus main body U3 by the conveyance path switching member GT1 pushes the conveyance direction regulating member constituted by an elastic thin film member, so-called mylar gate GT2. Passed and conveyed to the sheet reversing path SH4 of the image forming apparatus main body U3.
A sheet circulation path SH6 and a sheet reversing path SH7 of the sheet processing apparatus U4 are connected to the downstream end of the sheet reversing path SH4 of the image forming apparatus main body U3, and a Mylar gate GT3 is also disposed at the connecting portion. . The paper transported to the paper transport path SH4 through the switching gate GT1 passes through the mylar gate GT3 and is transported to the paper reversing path SH7. When performing duplex printing, the recording sheet S that has been transported through the paper reversing path SH4 passes through the Mylar gate GT3 as it is, is transported to the paper reversing path SH7, and then transported in the opposite direction. When switched back, the transport direction is regulated by the mylar gate GT3, and the recording sheet S switched back is transported to the paper circulation path SH6 side. The recording sheet S conveyed to the paper circulation path SH6 is retransmitted to the transfer area Q4 through the paper supply path SH1.
The sheet reversing path SH4, the sheet circulating path SH6, the sheet reversing path SH7, and the like constitute a sheet reversing path SH4 + SH6 + SH7 as an example of the reversing path of the first embodiment.

On the other hand, when the recording sheet S conveyed through the sheet reversing path SH4 is switched back after the trailing end of the recording sheet S passes through the Mylar gate GT2 and before passing through the Mylar gate GT3, the Mylar gate GT2 causes the recording sheet S to move. The conveyance direction is regulated, and the recording sheet S is conveyed to the sheet conveyance path SH5 with the front and back sides reversed. The recording sheet S whose front and back sides are reversed is subjected to curl correction by the curl correction device U4a, and then the image fixing surface of the paper S faces downward on the paper discharge tray TH1 of the paper processing device U4, so-called face-down state. Can be discharged.
A medium transport path SH is constituted by the elements indicated by the symbols SH1 to SH7. Further, the elements indicated by the symbols TR1 to TR4, SH, Ra, Rr, Rh, SGr, SG1, SG2, BH, GT1 to GT3, C, and the like constitute a sheet conveying device SU as an example of a medium conveying device. Has been.

(Description of image writing device)
FIG. 3 is an explanatory diagram of the image writing apparatus according to the first embodiment.
2 and 3, the latent image writing devices LHy to LHk as an example of the image writing device according to the first embodiment are arranged on the upstream side with respect to the sub-scanning direction that is the rotation direction of the photoconductors Py to Pk. An upstream head 1 as an example of the first writing member, and a first downstream head 2 and a second downstream head 3 as examples of a second writing member disposed on the downstream side of the upstream head 1. Have. Each of the heads 1 to 3 is an example of a writing element, and an LED 4: Light Emission Diode as an example of a light emitting element is on a line along the main scanning direction that is the width direction of the photosensitive bodies Py to Pk, that is, on a so-called array. It is comprised by the structure arrange | positioned along so-called LED head.
In FIG. 3, the upstream head 1 has a first writing set at the center in the main scanning direction, which is the width direction of the photoconductors Py to Pk, with respect to the maximum image writing width L1 of the photoconductors Py to Pk. A latent image as an example of an image is writable in the insertable area L2.

In addition, the first downstream head 2 is set from the front end, which is a part in the width direction of the photoconductors Py to Pk, to the center, and a part of the rear side overlaps the first writable area L2. The latent image can be written to two writable areas L3.
Further, the second downstream head 3 is set to a central portion from the rear end, which is a part in the width direction of the photoconductors Py to Pk, and a part of the front side overlaps the first writable area L2. A latent image can be written to three writable areas L4.

Therefore, as shown in FIG. 3, in the first embodiment, a first overlap region L6 as an example of a joint region by an overlapping region of the first writable region L2 and the second writable region L3. And a second overlap region L7 as an example of a joint region is formed by an overlapping region of the first writable region L2 and the third writable region L4.
Each of the heads 1 to 3 can form a latent image in the overlap areas L6 and L7. However, during an actual image forming operation, half of the overlap areas L6 and L7 are latent images in each of the heads 1 to 3. It is set to form.

(Description of Controller C of Example 1)
FIG. 4 is a block diagram illustrating the functions of the control unit of the image forming apparatus according to the first embodiment.
In FIG. 4, the controller C executes an input / output interface as an example of an input / output signal adjustment unit that performs input / output of an external signal and adjustment of an input / output signal level, so-called I / O, and necessary processing. A read-only memory, a so-called ROM, a random access memory for temporarily storing necessary data, a so-called RAM, and a process corresponding to the program stored in the ROM The computer is configured by a computer as an example of a computer having a central processing unit to be performed, a so-called CPU and a clock oscillator, and various functions can be realized by executing programs stored in the ROM.

(Signal input element connected to controller C)
The controller C receives a signal from a signal input element such as a user interface UI.
UI: User interface The user interface UI includes a display panel UI0 as an example of a display unit, a copy start key UI1 as an example of a copy start button, a numeric keypad UI2 as an example of a numeric input button, and an example of a copy number input button. A copy number input key UI3, an adjustment information input key UI4 as an example of an adjustment information input button, and the like are provided, and when these are input, a detection signal is input to the controller C.

(Control element connected to controller C)
The controller C is connected to the laser drive circuit D, the main motor drive circuit D1, the power supply circuit E, and other control elements, and outputs their operation control signals.

D: Laser drive circuit The laser drive circuit D controls the latent image forming apparatuses LHy to LHk to form a latent image.
D1: Main motor drive circuit A main motor drive circuit D1 as an example of a drive circuit for a main drive source is connected to the photoreceptors Py to Pk and developing units Gy to Gk via a main motor M1 as an example of a main drive source. The developing roll R0, the belt driving roll Rd, the fixing device F, and the like are driven to rotate.

E: Power Supply Circuit The power supply circuit E includes a development power supply circuit E1, a charging power supply circuit E2, a transfer roll power supply circuit E3, and a heating roll power supply circuit E4.
E1: Development power supply circuit The development power supply circuit E1 applies a development voltage to the development roll R0 of the development units Gy to Gk.
E2: Charging power supply circuit The charging power supply circuit E2 applies a charging voltage to the chargers CCy, CCm, CCc, CCk.
E3: Transfer Roll Power Supply Circuit The transfer roll power supply circuit E3 applies a transfer voltage to the primary transfer rolls T1y, T1m, T1c, T1k and the contact roll T2c of the transfer device T1 + B + T2 + CLB.
E4: Heating Roll Power Supply Circuit The heating roll power supply circuit E4 applies heating power to a heater as an example of a heating member of the heating roll Fh of the fixing device F.

(Function of controller C)
The controller C includes the following function realizing means for executing processing according to the output signal from each signal output element and outputting a control signal to each control element.
C1: Job Control Unit The job control unit C1 as an example of the image forming operation control unit is configured to output the latent image forming devices LHy to LHk, the image recording unit U3a, the fixing device F, and the sheet conveyance according to the input of the copy start key UI1. A job as an example of an image forming operation is executed by controlling the operation of the apparatus SU or the like.

C2: Main motor rotation control means A main motor rotation control means C2 as an example of a rotation control means for the main drive source controls the main motor drive circuit D1, and the photoreceptors Py to Pk and developing devices Gy to Gk, The rotational drive of the fixing device F or the like is controlled.
C3: Power supply circuit control means The power supply circuit control means C3 controls the power supply circuit E to develop the developing roll R0, the chargers CCy, CCm, CCc, CCk, the primary transfer rolls T1y, T1m, T1c, T1k, and the contact roll T2c. The voltage and current supply to the heater of the heating roll Fh of the fixing device F is controlled.

FIG. 5 is an explanatory diagram of a focus profile according to the first embodiment.
C4: Density unevenness adjustment means The density unevenness adjustment means C4 is an example of an adjustment information input determination means C4A, a power-on determination flag FL1, a focus profile presence / absence determination means C4B, a distribution information acquisition means C4C, and a correction information storage means. Correction table storage means C4D, correction table search means C4E as an example of correction information search means, correction information setting means C4F, and setting information storage means C4G. Adjust the density unevenness. As shown in FIG. 5, in each of the heads 1 to 3, the focus position distribution, so-called focus profile 6, has been found in the inspection process after manufacturing the LED head, and before the assembly process of the image forming apparatus U. Has been previously determined. Then, at the point where the focal position matches the surface of the photoreceptors Py to Pk with respect to the parabolic focus profile 6, the pixel of the image to be formed becomes the minimum and the set density, but the focal position does not match. In this case, the pixel becomes large and tends to be dark. Therefore, density unevenness occurs in the writable areas L1 to L3 of the heads 1 to 3, and density unevenness also occurs in comparison with the adjacent writable areas L1 to L3. Therefore, the density unevenness adjusting unit C4 according to the first embodiment adjusts density unevenness due to the difference in the focus profile 6 and the shift of the focus position.

C4A: Adjustment information input determination means The adjustment information input determination means C4A is based on the input to the adjustment information input key UI4 etc. of the user interface UI, and the heads 1 to 1 arranged in a line in the direction in which the light emitting element 4 writes the latent image. It is determined whether or not adjustment information that is information related to the focus profile 6 as an example of distribution information that is information specifying the light quantity distribution 3 is input. As the adjustment information of the first embodiment, as an example, it is possible to use information in which a focus deflection amount or a focus deflection amount that is a difference between the maximum and minimum focal lengths in the focus profile 6 is rated. For example, as the amount of deflection of the focus, information indicating that “the maximum deviation of ○ μm” is used, the degree of deflection is 0 to 5 μm, the rating is “A”, the amount of deflection is 5 to 10 μm, the rating is “B”,. Is possible.

FL1: Power-on determination flag The power-on determination flag FL1 as an example of the power-on determination means has an initial value of “0”, and is “1” when the power is turned on, that is, when the power is turned on. When the power is turned off, it is initialized to “0”.
C4B: Focus profile presence / absence discriminating means Focus profile presence / absence discriminating means C4B as an example of the focus distribution information presence / absence discriminating means determines whether or not information on the focus profile 6 exists in each of the heads 1 to 3 attached to the image forming apparatus U. Is determined. That is, each of the heads 1 to 3 supports a control board for controlling each light emitting element 4, and the information about the focus profile 6 is stored in a nonvolatile memory as an example of a storage medium provided on the control board. It is determined whether adjustment information is stored. The focus profile presence / absence discriminating means C4B according to the first exemplary embodiment does not perform the replacement operation of the heads 1 to 3 when the power of the image forming apparatus U is turned on. 3, the presence or absence of the focus profile 6 is determined when the power is turned on.

C4C: Distribution Information Acquisition Unit The distribution information acquisition unit C4C includes a focus profile acquisition unit C4C1 and an input adjustment information acquisition unit C4C2, and acquires information on a focus profile as an example of distribution information.
C4C1: Focus profile acquisition means The focus profile acquisition means C4C1 as an example of the focus distribution information acquisition means, when it is determined by the focus profile presence / absence determination means C4B that adjustment information related to the focus profile 6 exists in each of the heads 1 to 3. The adjustment information is obtained by reading it from the storage medium.
C4C2: Input Adjustment Information Acquisition Unit The input adjustment information acquisition unit C4C2 receives the adjustment information input from the user interface UI when the adjustment information input determination unit C4A determines that the adjustment information is input from the user interface UI. Read and get.

FIG. 6 is an explanatory diagram of a correction table according to the first embodiment, FIG. 6A is an explanatory diagram of a correction table set corresponding to a convex focus profile having a large focal deflection amount, and FIG. 6B is a small focal deflection amount. FIG. 6C is an explanatory diagram of a correction table set in correspondence with a concave focus profile having a large focal deflection amount. FIG. 6C is an explanatory diagram of a correction table set in correspondence with a convex focus profile.
C4D: Correction Table Storage Unit The correction table storage unit C4D as an example of the correction information storage unit stores a correction table as an example of preset correction information corresponding to the focus profile 6 for each of the heads 1 to 3. . In FIG. 6, the correction table storage unit C4D according to the first embodiment uses the end in the main scanning direction as a reference with respect to the focus profile 6 shown in FIG. A certain lighting duty is set to “1”, and a correction table 7 is stored in which the lighting duty decreases as the focal length increases. In the first embodiment, for easy understanding, the light emitting element 4 in which the heads 1 to 3 are arranged in the main scanning direction is divided into five blocks, and the lighting duty is set for each division. explain. Note that the number of divisions can be arbitrarily changed, and can be one element at a time.

Similarly, a correction table 7 in which a lighting duty is set is stored for the focus profile 6 shown in FIGS. 6B and 6C. That is, the correction table 7 is stored corresponding to a plurality of focus profiles 6 that are different for each of the heads 1 to 3 due to differences in manufacturing factories, manufacturing units, so-called lots, and the like.
In the first embodiment, adjustment information for specifying the focus profile 6 is stored in association with each correction table 7. As an example, the correction table 7 shown in FIG. 6A has a focus deflection amount of “10 μm” and a rating of “B”, and the correction table 7 shown in FIG. 6B has a focus deflection amount of “5 μm” and a rating of “A”. In the correction table 7 shown in FIG. 6C, adjustment information is stored in association with each other such that the focal deflection amount is “−10 μm” and the rating is “C”.

C4E: Correction table search unit The correction table search unit C4E searches the correction table 7 stored in the correction table storage unit C4D for the correction table 7 corresponding to the focus profile 6 acquired by the distribution information acquisition unit C4C. . The correction table search unit C4E according to the first embodiment searches the correction table 7 associated with the corresponding adjustment information based on the adjustment information for specifying the focus profile 6 acquired by the distribution information acquisition unit C4C.
C4F: Correction Information Setting Unit The correction information setting unit C4F sets a correction table 7 that equalizes the image density written by each head 1 to 3 for each head 1 to 3 based on the focus profile 6. The correction information setting unit C4F according to the first embodiment sets the correction table 7 searched by the correction table search unit C4E as the correction table 7 used when the heads 1 to 3 write an image.

C4G: Setting Information Storage Unit The setting information storage unit C4G stores the correction table 7 set by the correction information setting unit C4F. The setting information storage unit C4G according to the first embodiment stores the correction table 7 set for each of the heads 1 to 3.
C5: Image processing means The image processing means C5 has an image dividing means C5A and a gradation correcting means C5B, and is supplied from image information read by the image input device U1 or an image information transmitting device such as a personal computer (not shown). When printing the transmitted image information or the like, image processing, which is processing for converting the image information to be printed into information for writing in the latent image forming apparatuses LHy to LHk, is performed.
C5A: Image Dividing Unit The image dividing unit C5A divides the image written by each of the heads 1 to 3 based on the size of the received image information. That is, the image is divided corresponding to the writable areas L2 to L4 of the heads 1 to 3.

FIG. 7 is an explanatory diagram of an example of gradation correction according to the first embodiment. FIG. 7A is an explanatory diagram before gradation correction, and FIG. 7B is an explanatory diagram after gradation correction.
C5B: Gradation correction unit The gradation correction unit C5B corrects the gradation of the image to be written based on the correction table 7 set by the correction information setting unit C4F. The tone correction unit C5B according to the first embodiment corrects the tone of the density of the image information to be printed based on the correction table 7 set by the correction information setting unit C4F. In FIG. 7, as an example, when the density of image information to be printed is “50%”, when converted to a gradation image, as shown in FIG. Consider the case where it is filled. In the gradation image of FIG. 7A, when the correction table 7 shown in FIG. 6A is set as the correction table 7, the gradation image shown in FIG. 7A is written in the section where the lighting duty is “1”. On the other hand, in the section where the lighting duty is “0.7”, the density is corrected to 50% × 0.7 = 35%, and as shown in FIG. 7B, the gradation density in which 6 out of 16 are filled is written. Gradation correction is performed as described above.

C6: Write Control Unit The write control unit C6 includes a first write control unit C6A, a second write control unit C6B, and a third write control unit C6C, and forms a latent image. The devices LHy to LHk are controlled to form latent images on the surfaces of the photoreceptors Py to Pk. The writing control unit C6 according to the first embodiment operates the latent image forming apparatuses LHy to LHk based on information on which image processing such as image division and gradation correction is performed by the image processing unit C5, thereby writing a latent image. Control. That is, the writing control means C6 of the first embodiment controls the writing of the latent image by operating the heads 1 to 3 based on the correction table 7 set by the correction information setting means C4F.
C6A: First Write Control Unit The first write control unit C6A controls the upstream head 1 to write a latent image in the first writable area L2.

C6B: Second Write Control Unit The second write control unit C6B controls the first downstream head 2 to write a latent image in the second writable area L3. The second writing control unit C6B according to the first embodiment uses the latent image written by the upstream head 1 as the first downstream head in order to match the seam in the main scanning direction to the latent image written by the upstream head 1. The latent image is written while the writing time is shifted by the splicing time corresponding to the rotation time of the photoconductors Py to Pk corresponding to reaching the position 2.
C6C: Third Write Control Unit The third write control unit C6C controls the second downstream head 3 to write a latent image in the third writable area L4. Similarly to the second write control unit C6B, the third write control unit C6C according to the first embodiment uses the upstream head to match the latent image written by the upstream head 1 in the main scanning direction. The latent image is written by shifting the writing time by the splicing time corresponding to the rotation time of the photoconductors Py to Pk corresponding to the latent image written by 1 reaching the position of the first downstream head 2.

(Explanation of flowchart of Example 1)
Next, a processing flow of the image forming apparatus U according to the first exemplary embodiment of the present invention will be described with reference to a flowchart, that is, a so-called flowchart.
(Description of Flowchart of Density Unevenness Adjustment Processing in Example 1)
FIG. 8 is a flowchart of density unevenness adjustment processing according to the first embodiment of the present invention.
The process of each step ST in the flowchart of FIG. 8 is performed according to a program stored in the controller C of the image forming apparatus U. Further, this processing is executed in parallel processing in parallel with other various processing of the image forming apparatus U.
The flowchart shown in FIG. 8 is started when the image forming apparatus U is powered on.

In ST1 of FIG. 8, it is determined whether or not the power-on determination flag FL1 is “0”, that is, whether or not it is immediately after power-on. If no (N), the process proceeds to ST2, and if yes (Y), the process proceeds to ST3.
In ST2, it is determined whether or not adjustment information has been input from the user interface UI. If yes (Y), the process proceeds to ST6, and if no (N), the process returns to ST1.
In ST3, the power-on determination flag FL1 is set to “1”, and the process proceeds to ST4.
In ST4, it is determined whether or not adjustment information, which is information related to the focus profile 6, is stored in the storage medium of each of the heads 1 to 3. If yes (Y), the process proceeds to ST5. If no (N), the process returns to ST1.
In ST5, the adjustment information regarding the focus profile 6 stored in the storage medium of each of the heads 1 to 3 is read. Then, the process proceeds to ST6.
In ST6, the correction table 7 corresponding to the input from the user interface UI or the adjustment information read from the heads 1 to 3 is searched for each of the heads 1 to 3 of the latent image forming apparatuses LHy to LHk for each color. The correction table 7 used during the image forming operation is set. Then, the process returns to ST1.

(Operation of Example 1)
In the image forming apparatus U of the first embodiment having the above configuration, when the heads 1 to 3 are attached to the image forming apparatus U, the adjustment information is automatically read from the storage medium of the heads 1 to 3 when the power is turned on. The correction table 7 to be searched is automatically searched and set automatically. Even when the adjustment information is not stored in the storage medium, when the adjustment information is input from the user interface UI by an operator such as a technician, the correction table 7 is automatically retrieved and automatically Is set. Then, based on the set correction table 7, image processing is performed so that the density distribution for each section is uniformized, and writing is performed. Therefore, density unevenness of the formed image is reduced.

  Conventional adjustment of density unevenness reflects the complicated operation of printing a preset image on paper and then reading the paper on which the image is printed, and correction information of the latent image forming apparatus from the read density. A system to make it necessary was necessary. On the other hand, in the first embodiment, the correction table 7 corresponding to the manufacturing factory and lot is stored in advance, and the adjustment information is input from the user interface UI when the adjustment information is stored in the heads 1 to 3. The correction table 7 is automatically retrieved and set. Therefore, complicated operations and complicated systems are reduced compared to the conventional configuration, and density unevenness can be adjusted by a simple method.

  When the image forming apparatus U is not a model corresponding to “A3” for general offices but a model corresponding to “A1” or “A0” such as a design drawing or poster printing, the latent image forming apparatuses LHy to LHk are Although it is possible to configure with one LED head, it becomes a special order and the cost increases, and the length in the main scanning direction becomes long, and it becomes difficult to adjust density unevenness. On the other hand, the LED heads 1 to 3 used in general office models are mass-produced and are available at a relatively low price. It is advantageous in terms of price to manufacture a plurality of latent image forming apparatuses LHy to LHk side by side as in the first embodiment. In this case, as in the conventional technique, for example, printing on “A0” paper and then reading an image of the printed paper is very complicated and burdensome. Therefore, the density unevenness adjusting method of the first embodiment is particularly effective in such a case.

  In the first embodiment, adjustment information can be input from the user interface UI, and it is possible to cope with a failure after the image forming apparatus U is assembled.

FIG. 9 is a block diagram of the second embodiment and corresponds to FIG. 4 of the first embodiment.
Next, the second embodiment of the present invention will be described. In the description of the second embodiment, the same reference numerals are given to the components corresponding to the components of the first embodiment, and the detailed description thereof will be given. Omitted.
The second embodiment is different from the first embodiment in the following points, but is configured in the same manner as the first embodiment in other points.

(Function of controller C)
The controller C of the second embodiment has a distribution information acquisition unit C4C ′ and a correction information calculation unit C4H in place of the distribution information acquisition unit C4C, the correction table storage unit C4D, and the correction table search unit C4E of the first embodiment. Since it is the same, detailed description is omitted about the same part.

FIG. 10 is an explanatory diagram of adjustment information according to the first embodiment, FIG. 10A is an explanatory diagram of a waveform focus profile, and FIG. 10B is an explanatory diagram of a convex focus profile.
C4C ′: Distribution Information Acquisition Unit The distribution information acquisition unit C4C ′ includes a focus profile acquisition unit C4C1 and an input adjustment information acquisition unit C4C2, and acquires information on a focus profile as an example of distribution information. In FIG. 10, the distribution information acquisition unit C4C ′ according to the second embodiment acquires information on a polynomial that identifies the focus profile 6 as information regarding the focus profile 6 instead of the focus deflection amount and rating information according to the first embodiment. In the second embodiment, a0 × x ⁿ + a1 × x ⁿ⁻¹ +... + An and b0 × x ⁿ + b1 × x ⁿ⁻¹ +... + ^Bn are used as information on a polynomial specifying the focus profile 6 shown in FIGS. 10A and 10B. The coefficients (a0, a1,..., An) and (b0, b1,..., Bn) represented by the following can be stored as adjustment information in the storage medium of the heads 1 to 3 or input from the user interface UI. It is configured. The polynomial is not limited to the case where it completely coincides with the focus profile 6, and is used to include an approximate polynomial.

C4H: Correction Information Calculation Unit The correction information calculation unit C4H calculates correction information for making the density of the formed image uniform based on the adjustment information regarding the focus profile 6 acquired by the distribution information acquisition unit C4C ′. . The correction information calculation unit C4H according to the second embodiment calculates the correction information so that the focus profile 6 specified by the polynomial having the acquired coefficient is canceled and unevenness is reduced. In the correction information calculation means C4H according to the second embodiment, as an example, the same information as that of the correction table 7 is obtained from the average of each section by dividing the same information as the correction table 7 according to the first embodiment based on the polynomial information. Is calculated.

(Explanation of flowchart of Example 2)
Next, a processing flow of the image forming apparatus U according to the second exemplary embodiment of the present invention will be described with reference to a flowchart.
(Description of Flowchart of Density Unevenness Adjustment Processing of Example 2)
FIG. 11 is a flowchart of density unevenness adjustment processing according to the second embodiment of the present invention.
In FIG. 11, in the density unevenness adjustment process of the second embodiment, the following process ST6 ′ is executed in place of ST6 of the density unevenness adjustment process of the first embodiment. Detailed description of this part is omitted.
In ST6 ′ of FIG. 11, a correction table 7 as an example of correction information is calculated and set based on the acquired adjustment information. Then, the process returns to ST1.

(Operation of Example 2)
In the image forming apparatus U according to the second embodiment having the above-described configuration, unlike the first embodiment, correction information is automatically calculated and automatically set based on adjustment information of a polynomial that specifies the focus profile 6. . Accordingly, even if the correction table 7 is not stored in advance as in the first embodiment, an appropriate correction table 7 is automatically generated each time based on the polynomial information stored in the storage medium of the heads 1 to 3. Is calculated and set. Therefore, it is possible to reduce the storage capacity of the storage device as compared with the case where the correction table 7 is stored.
Therefore, in the image forming apparatus U according to the second embodiment, as in the first embodiment, as in the conventional technique, an image is output on paper to adjust density unevenness, and the output paper is read. No work is required, and density unevenness can be adjusted by a simple method.

FIG. 12 is a block diagram of the third embodiment and corresponds to FIG. 4 of the first embodiment.
Next, the third embodiment of the present invention will be described. In the description of the third embodiment, the same reference numerals are given to the components corresponding to the components of the first embodiment, and the detailed description thereof will be given. Omitted.
The third embodiment is different from the first embodiment in the following points, but is configured in the same manner as the first embodiment in other points.

(Function of controller C)
In the controller C of the third embodiment, the gradation correction unit C5B of the first embodiment is omitted, and the write control unit C6 of the third embodiment includes an initial light amount information acquisition unit C6D and a light amount control calculation unit C6E. Have been added. Therefore, in the third embodiment, unlike the first embodiment, tone correction is not performed based on the correction table 7, and a tone image corresponding to image information to be printed is created.

FIG. 13 is an explanatory diagram of density unevenness adjustment according to the third embodiment. FIG. 13A is an explanatory diagram of the relationship between the initial light amount control information and the correction table. FIG. 13B is a state in which the light amount control information is calculated based on the correction table. It is explanatory drawing.
C6D: Initial light amount information acquisition unit The initial light amount information acquisition unit C6D controls the light amount of each light emitting element 4 set in advance so that the heads 1 to 3 of the latent image forming apparatuses LHy to LHk have the focus profile 6. The initial light quantity control information which is information is acquired. The initial light quantity information acquisition unit C6D of Example 1 acquires the initial light quantity control information stored in the storage medium of each of the heads 1 to 3 by reading it. In FIG. 13, for example, in the stage of manufacturing the heads 1 to 3, when the heads 1 to 3 are manufactured so as to have the focus profile 6 shown in FIG. 6A, each of the light emitting elements 4 constituting the heads 1 to 3 is manufactured. Therefore, as shown in the upper part of FIG. 13A, initial light amount control information 8 for correcting the lighting duty for each of the light emitting elements 4 or for each set of the plurality of elements 4 is recorded in each head 1. 3 is stored in a storage medium incorporated in the three substrates. Therefore, the initial light amount information acquisition unit C6D according to the third embodiment acquires the initial light amount control information 8 stored in the storage medium of each head 1 to 3 by reading.

C6E: Light quantity control calculation means The light quantity control calculation means C6E controls the light quantity of the light emitting element 4 based on the initial light quantity control information 8 acquired by the initial light quantity information acquisition means C6D and the correction table 7. 9 is calculated. In FIG. 13, the focus profile 6 shown in FIG. 6A will be described as an example. The initial light quantity information acquisition unit C6D acquires the initial light quantity control information 8 shown in the upper part of FIG. 13A, and the correction table 7 as in the first embodiment. And the correction table 7 shown in the lower part of FIG. 13A is set. Based on the initial light amount control information 8 and the correction table 7, the light amount control calculation unit C6E of Example 3 calculates the light amount control information 9 so that the focus profile 6 is uniformed as shown in FIG. 13B. The
Each of the writing control means C6A to C6C performs light amount control of each head 1 to 3 based on the calculated light amount control information 9, and performs image writing.

(Explanation of flowchart of Example 3)
Next, a processing flow of the image forming apparatus U according to the third exemplary embodiment of the present invention will be described with reference to a flowchart.
(Description of Flowchart of Density Unevenness Adjustment Processing in Embodiment 3)
FIG. 14 is a flowchart of density unevenness adjustment processing according to the third embodiment of the present invention.
In FIG. 14, in the density unevenness adjustment process of the third embodiment, the following processes ST7 to ST8 are executed after ST6 of the density unevenness adjustment process of the first embodiment. Detailed description of this part is omitted.
In ST7 of FIG. 14, initial light quantity control information 8 is acquired. Then, the process proceeds to ST8.
In ST8, the light amount control information 9 is calculated from the correction table 7 and the initial light amount correction information 8, and set as light amount control information used for image formation. Then, the process returns to ST1.

(Operation of Example 3)
In the image forming apparatus U according to the third embodiment having the above configuration, when the correction table 7 is automatically searched and set from the adjustment information of the focus profile 6, the light amount control is performed from the correction table 7 and the initial light amount control information 8. Calculation of information 9 is performed. That is, in the third embodiment, the light amount correction of each of the heads 1 to 3 is performed instead of the gradation correction as in the first embodiment. Therefore, unlike the first and second embodiments, in which density unevenness is suppressed by image processing, in the third embodiment, the light amount at the time of writing by the heads 1 to 3 of the latent image forming apparatuses LHy to LHk is directly corrected. Accordingly, it is possible to cope with density unevenness only on the latent image forming apparatuses LHy to LHk side, and it is not necessary to adjust or correct other members of the image forming apparatus U such as image processing.
Therefore, also in the image forming apparatus U of the third embodiment, as in the first and second embodiments, as in the prior art, an image is output to paper or the output paper is read in order to adjust density unevenness. Thus, the density unevenness can be adjusted by a simple method.

FIG. 15 is an explanatory diagram of a main part of the latent image forming apparatus according to the fourth embodiment.
Next, a description will be given of a fourth embodiment of the present invention. In the description of the fourth embodiment, the same reference numerals are given to the components corresponding to the components of the first embodiment, and a detailed description thereof will be given. Omitted.
The fourth embodiment is different from the first embodiment in the following points, but is configured in the same manner as the first embodiment in other points.
Next, the latent image forming apparatuses LHy to LHk according to the fourth embodiment will be described with reference to FIG. 15. The latent image forming apparatuses LHy to LHk for each color Y, M, C, and K are configured in the same manner. Therefore, only the Y-color latent image forming device LHy will be described in detail, and detailed descriptions of the other color latent image forming devices LHm to LHk will be omitted.

  In FIG. 15, in the latent image forming apparatus LHy of Example 4, the upstream head 1 has a head body 11 extending in the main scanning direction. A plurality of light emitting elements 4 are arranged in an array on the surface of the head main body 11 on the photosensitive member Py side. A rotation shaft 12 extending in a direction away from the photoreceptor Py is supported at the center of the head body 11 in the main scanning direction. A pair of guided pins 13 extending in a direction away from the photoreceptor Py is supported as an example of a guided portion at both ends of the head main body 11 in the main scanning direction.

In the upstream head 1 of the fourth embodiment, the rotary shaft 12 is rotatably supported by a circular support hole 16 formed in a head fixing member (not shown) of the image forming apparatus main body U3 as an example of a support member. . The head fixing member is supported in a movable state corresponding to the guided pin 13 in a long hole-like guide hole 17 along an arc centered on the support hole 16. Therefore, the upstream head 1 of the fourth embodiment is supported so as to be rotatable and tiltable along the sub-scanning direction, which is the rotation direction Yb of the photosensitive member Py, with the support hole 16 as the center. The rotating shaft 12 and the guided pin 13 are supported so as to be movable along the axial direction, that is, the direction approaching and separating from the photoreceptor Py.
The first downstream head 2 and the second downstream head 3 are also configured similarly to the upstream head 1.

(Density unevenness adjustment method)
FIG. 16 is an explanatory diagram of the density unevenness adjusting method of the fourth embodiment, and is an explanatory diagram of an alignment process.
FIG. 17 is an explanatory view of the density unevenness adjusting method of the fourth embodiment, and is an explanatory view of the inclination matching step.
18A and 18B are explanatory diagrams of a calculation method of the inclination angle in the density unevenness adjustment method of the fourth embodiment. FIG. 18A is a plan view and FIG.

16 to 18, when adjusting the density unevenness of the latent image forming apparatuses LHy to LHk according to the fourth embodiment, as shown in FIG. 16, the heads 1 to 3 are moved closer to the photoreceptors Py to Pk. The position is adjusted so that the maximum position of the focus profile 6 coincides with the surface of the photoreceptors Py to Pk by moving in the direction of separation. Next, as shown in FIG. 17, the heads 2 and 3 having a large focal deflection amount are tilted with respect to the sub-scanning direction of the photoconductors Py to Pk. 17 and 18, when the heads 2 and 3 are tilted, the distance between the light emitting element 4 and the photoconductors Py to Pk does not change at the point of rotation center, that is, the focal point position is the same. Increase in the distance between the light emitting element 4 at the outer edge in the main scanning direction and the photoreceptors Py to Pk that do not match, and the deviation from the focal length is reduced. In FIG. 18, when correction is performed for the maximum focal deflection amount Δy at both ends where the focal deflection amount is the maximum, the distance from the outer light emitting element 4 to the other outer light emitting element 4 in the main scanning direction is expressed as x. When the inclination angle of the heads 1 to 3 is θ and the radius of the photoreceptors Py to Pk is r, the heads 1 to 3 are rotated by the inclination angle θ derived from the following equation (1). The maximum focus deflection amount Δy can be corrected.
Δy = r−r × cos [sin ⁻¹ [{(x / 2) × sin θ} / r]] Equation (1)

FIG. 19 is an explanatory diagram of a conventional density unevenness correction method described in Patent Document 4.
20A and 20B are explanatory diagrams of changes in the focus profile in the density unevenness correction method of the prior art shown in FIG. 19, FIG. 20A is an explanatory diagram when moved in parallel, and FIG. 20B is a case when tilted with respect to the main scanning direction. It is explanatory drawing of.
(Operation of Example 4)
In the image forming apparatus U according to the fourth embodiment having the above-described configuration, the maximum positions of the focal lengths of the heads 1 to 3, so-called peak points, are aligned according to the focus profile 6 and according to the focus deflection amount. The heads 1 to 3 are inclined to reduce the focal length unevenness. Therefore, density unevenness of the formed image is reduced.

19 and 20, in the conventional density unevenness adjustment method such as the technique disclosed in Patent Document 4, the adjustment is performed simply by raising and lowering the photosensitive member 04 along the pins 02 and 03 at both ends of the head 01. By raising and lowering the pins 02 and 03 by the same amount, the head 01 moves in parallel, and as shown in FIG. 20A, the focus profile moves in parallel as a whole. Further, by setting the lifts of the pins 02 and 03 to be different, the head 01 is inclined in the main scanning direction, and the focus profile is rotated as shown in FIG. 20B. Therefore, with the conventional method, it is impossible to eliminate density unevenness at the maximum part of the focus profile.
In the technique disclosed in Patent Document 5, the head is deformed and focused, but the amount of focus shift is actually a very small amount of several μm. Therefore, it is difficult to deform under an appropriate load as in the technique described in Patent Document 5, and a mechanism for the deformation is required, which causes a problem of an increase in price.
Therefore, in the image forming apparatus of Example 4, it is possible to adjust density unevenness by a simple method as compared with the configurations described in Patent Documents 4 and 5.

FIG. 21 is an explanatory diagram of a modification of the fourth embodiment.
In addition, although Example 4 illustrated the case where the operation | work which aligns the peak point of each head 1-3 and the operation | work which makes it incline was illustrated, it is not limited to this, It is also possible to carry out automatically.
In FIG. 21, in the heads 1 to 3 of the modified example of the fourth embodiment, a rotated gear 21 as an example of a gear is supported at the end of the rotating shaft 12, and the rotated gear 21 is an example of a drive source. The rotary gear 22 as an example of a gear to which the drive from the motor M1 is transmitted is engaged. Note that the axial length of the rotated gear 21 is long depending on the amount of elevation of the heads 1 to 3, and fixed rotation is possible even when the rotated gear 21 moves up and down relative to the surface of the photoreceptor Py. It is held in mesh with the gear 22.

A rack 23 as an example of an elevating transmission member is supported at the end of the guided pin 13. The rack 23 is formed with a gear portion 23a as an example of a gear portion, and a pinion gear 24 as an example of an elevating gear meshes with the gear portion 23a. The pinion gear 24 is supported so as to be integrally rotatable with the rotation of the head body 11, and the drive is transmitted to the pinion gear 24 from a motor M2 as an example of a drive source via an elastic belt (not shown). Is done.
Therefore, when the drive from the motor M2 is transmitted to the pinion gear 24, the head body 11 moves up and down with respect to the photoreceptors Py to Pk via the rack 23 and the guide pins 13.
Therefore, in the modified example of the fourth embodiment, the adjustment information stored in the storage medium of each of the heads 1 to 3 is acquired and the pinion gear 24 is driven based on the adjustment information, as in the first to third embodiments. It is also possible to automatically perform operations such as aligning the peak points, calculating the tilt angle θ from the adjustment information, and controlling the motor M2 to tilt the calculated tilt angle θ.

In Example 4, when each of the heads 1 to 3 is inclined in the sub-scanning direction, among the same heads 1 to 3, the light emitting element at one end in the main scanning direction, the light emitting element at the center, and the light emission at the other end side. If the element emits light simultaneously, the images formed on the surfaces of the photoreceptors Py to Pk may be inclined. On the other hand, when the tilt angle θ is automatically calculated or input from the user interface UI, when the distance from the rotation axis 12 of the n light emitting elements outside the rotation axis 12 is xn, The distance Δzn calculated by the equation (2) is shifted in the sub-scanning direction. Therefore, the tilt of the image can be prevented by causing the light to be emitted at different timings by the distance Δzn and the rotational speed of the photoconductors Py to Pk. Is possible.
Δzn = xn × sin θ (2)

Even when each of the heads 1 to 3 is inclined, the writable areas L2 to L4 overlap each other, that is, overlap each other, and it is prevented that writing cannot be performed at a joint. . That is, in the overlap regions L6 and L7, the heads 1 to 3 form an overlapping image, thereby preventing an image from being formed at the joint.
In addition, when unevenness that cannot be corrected remains after the density unevenness adjustment of Example 4, the density unevenness adjustment is repeated using the configuration described in any of Examples 1 to 3. It is also possible to do this.

(Example of change)
As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to the said Example, A various change is performed within the range of the summary of this invention described in the claim. It is possible. Modification examples (H01) to (H06) of the present invention are exemplified below.
(H01) In the above-described embodiment, the copying machine U is exemplified as the image forming apparatus. However, the present invention is not limited to this. For example, the copying machine U may be configured by a printer, a FAX, or a multifunction machine having a plurality or all of these functions. Is possible.
(H02) In the above embodiment, an image forming apparatus using four color developers is illustrated, but the present invention is not limited to this configuration. For example, five or more colors, three colors or less, or a so-called monochrome image formation. It is also applicable to the device.

(H03) In the above embodiment, the configuration using three heads 1 to 3 has been described. However, the number of heads 1 to 3 is not limited to three, and may be one or two. It is also possible to use four or more.
(H04) In the above-described embodiments, the exemplified numerical values can be appropriately changed according to the design, specifications, and the like.
(H05) In the first and second embodiments, the gradation correction is exemplified as the correction method using the correction data. However, the present invention is not limited to this, and for example, the lighting time and the light emission output can be corrected. is there. Moreover, adjustment information is not limited to the illustrated information, Arbitrary information can be used if it is the information relevant to the light quantity distribution of the light emitting element 4. FIG.

(H06) In the above-described embodiment, the correction table 7 is exemplified as the correction information. However, the correction information is not limited to information such as a table, and can be correction information in an arbitrary format.

1, 2, 3 ... writing member,
4 ... Light emitting element,
6 ... Distribution information,
7: Correction information,
8: Initial light quantity control information,
9: Light quantity control information,
12 ... rotating shaft,
C4C ... Distribution information acquisition means,
C4D: Correction information storage means,
C4E: correction information search means,
C4F: correction information setting means,
C4H: Correction information calculation means,
C6: Write control means,
C6E: Light amount control calculation means,
F: Fixing device,
Gy, Gm, Gc, Gk ... developing device,
LHy, LHm, LHc, LHk ... Image writing device,
Py, Pm, Pc, Pk ... image carrier,
S ... medium
T1 + B + T2 + CLB ... transfer device,
U: Image forming apparatus,
UI: Input unit.

Claims (13)

A writing member having a plurality of light emitting elements arranged in a direction to write a latent image, and writing the latent image on the surface of the image carrier;
Distribution information acquisition means for acquiring distribution information for specifying a light amount distribution of the light emitting element measured in advance for each writing member;
Correction information setting means for setting correction information for making the image density written by the writing member uniform based on distribution information;
A writing control means for controlling writing of a latent image by operating the writing member based on the correction information set by the correction information setting means;
An image writing apparatus comprising: A storage medium supported by the writing member and storing the distribution information;
The distribution information acquisition means for acquiring the distribution information stored in the storage medium;
The image writing apparatus according to claim 1, further comprising: An input unit that can be entered by the operator;
The distribution information acquisition means for acquiring the distribution information input from the input unit;
The image writing apparatus according to claim 1, further comprising: Correction information storage means for storing correction information set in advance corresponding to the distribution information for each of the writing members;
The correction information setting means for setting the correction information corresponding to the distribution information acquired by the distribution information acquisition means from among the correction information stored in the correction information storage means;
The image writing apparatus according to claim 1, further comprising: Correction information calculation means for calculating the correction information based on the distribution information acquired by the distribution information acquisition means;
The correction information setting means for setting the correction information calculated by the correction information calculation means;
The image writing apparatus according to claim 1, further comprising: The write control means for controlling the writing of the latent image by controlling the light amount of each light emitting element based on the correction information set by the correction information setting means;
The image writing apparatus according to claim 1, further comprising: Light amount control for controlling the light amount of the light emitting element based on the initial light amount control information, which is information for controlling the light amount of each light emitting element set in advance so as to be the light amount distribution of the light emitting element, and the correction information A light amount control calculating means for calculating information;
The writing control means for controlling writing of a latent image based on the light amount control information;
The image writing apparatus according to claim 6, further comprising: The write control means for controlling the writing of the latent image by correcting the gradation of the image to be written based on the correction information set by the correction information setting means;
The image writing apparatus according to claim 1, further comprising: The writing member supported based on the light amount distribution and tilted along the sub-scanning direction of the image carrier so that the focal position of each light emitting element is on the surface of the image carrier;
The image writing apparatus according to claim 1, further comprising: The writing member supported so as to be tiltable along a sub-scanning direction of the image carrier, with a rotation axis extending along a direction approaching and separating from the image carrier as a center.
The image writing apparatus according to claim 9, further comprising: The photosensitive member surface is supported so as to be movable toward and away from the image carrier, and is in a state along the main scanning direction of the image carrier and the focal length of the writing member is maximum. The writing member supported in a state inclined from the state corresponding to the sub-scanning direction,
The image writing apparatus according to claim 9 or 10, further comprising: A plurality of the writing members arranged along the main scanning direction of the image carrier,
The image writing apparatus according to claim 1, further comprising: An image carrier,
The image writing device according to any one of claims 1 to 12, wherein a latent image is formed on the surface of the image carrier.
A developing device for developing the latent image on the surface of the image carrier into a visible image;
A transfer device for finally transferring a visible image of the surface of the image carrier to a medium;
A fixing device for fixing the visible image transferred to the medium;
An image forming apparatus comprising: