JP2015177406A - Image reading device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce color slippage in a read multi-color image.SOLUTION: An image reading device (U2) includes: a reading unit (U2a) in which light-receiving elements are arranged in one line in a second direction; light source control means (C1) which controls light emission of light source members (31-33), emits a first color (R), a second color (G) and a third color (B) iteratively in order on the basis of reference signals outputted at preset time intervals (t1) and performs control in such a manner that the light emission of the first color (R) is made close to light emission start timing (tc) of the second color (G) and that the light emission of the third color (B) is made close to light emission end timing (td) of the second color (G).

Description

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

  2. Description of the Related Art Conventionally, a technique described in Patent Document 1 below is known for a medium on which an image is recorded, that is, a so-called image reading apparatus that reads an original.

  Japanese Patent Laid-Open No. 2006-304200 as Patent Document 1 discloses that when the contact image sensor (101) is moved in the sub-scanning direction along the document, red (R), green (G), A configuration is described in which the blue (B) LEDs (102) are switched on to emit light of each color, and the reflected light from the original is read by the monochrome image sensor (104). In the configuration described in Patent Document 1, each of the R, G, and B LEDs (102) is turned on when the reference pulse signal is turned on, the pre-scan is performed, and the R, G, and B LEDs are turned on. When the time for storing the data set for each color elapses, the light is turned off. That is, control is performed with the same lighting timing but different lighting times.

JP 2006-304200 A (“0005”, “0011”, “0016”, “0019”, FIGS. 5 and 6)

  An object of the present invention is to reduce color misregistration between read monochrome images.

In order to solve the technical problem, an image reading apparatus according to claim 1 is provided.
A light source unit that emits light toward a document on which an image is recorded, the first light source member that irradiates light of a first color, and light of a second color different from the first color. The light source unit including: a second light source member that irradiates; and a third light source member that emits light of a third color different from the first color and the second color;
A reading unit that moves relative to a document in a first direction set in advance and reads the document, and receives a light reflected from the document in the first direction. The reading units arranged side by side so as to receive light along the intersecting second direction;
Light source control means for controlling the light emission of each light source member, and sequentially repeating the first color, the second color, and the third color based on a reference signal output at a preset time interval The light emission of the first color is controlled to be close to the light emission start time of the second color, and the light emission of the third color is controlled to be close to the light emission end time of the second color. The light source control means;
It is provided with.

According to a second aspect of the present invention, in the image reading apparatus according to the first aspect,
The light emission period of the second color is set longer than the light emission periods of the first color and the third color.

According to a third aspect of the present invention, in the image reading device according to the second aspect,
The light emission intensities of the first and third colors are made stronger than the light emission intensity of the second color.

According to a fourth aspect of the present invention, in the image reading apparatus according to any one of the first to third aspects,
Based on a temporal shift between the first color and the second color, interpolation processing of the first color at the position of the second color is performed, and the third color and the second color are performed. Interpolation processing means for performing interpolation processing of the third color at the position of the second color based on temporal deviation from the color of
It is provided with.

In order to solve the technical problem, an image forming apparatus according to claim 5 is provided.
An image reading device according to any one of claims 1 to 4, which reads an image from a medium;
An image recording unit for recording an image on a medium based on an image read by the image reading device;
It is provided with.

According to the first and fifth aspects of the present invention, when a multicolor image is created from an image read with a different single color, rather than emitting different single colors at the same interval, the color of each single color image can be changed. Deviation can be suppressed.
According to the second aspect of the present invention, when a multicolor image is created, the color between the single colors is larger than when the color with a large positional correction and the small color are emitted with the same length. It is possible to suppress the deviation.
According to the third aspect of the present invention, compared with the case where the light emission length is different and the light intensity is not different, the output between the respective colors can be made the same.
According to the fourth aspect of the present invention, color misregistration can be reduced compared to a case where no interpolation processing is performed.

FIG. 1 is an overall explanatory view of an image forming apparatus according to a first embodiment. FIG. 2 is an explanatory diagram of a main part of an image recording unit according to the first embodiment. FIG. 3 is a perspective view of the image reading apparatus and the opening / closing member according to the first embodiment. FIG. 4 is an explanatory diagram of the image reading apparatus according to the first embodiment. FIG. 5 is an explanatory diagram of a main part of the light source unit according to the first embodiment. FIG. 6 is an explanatory diagram of a time chart of light source control according to the first embodiment. FIG. 7 is an explanatory diagram of a read image correction process according to the first embodiment. FIG. 8 is an explanatory diagram of conventional image reading, FIG. 8A is a time chart of conventional light control, FIG. 8B is a black line image as an example of a document image, and FIG. 8C is a document image of FIG. 8B. 8D is an explanatory diagram of the read image of the original image of FIG. 8B, FIG. 8E is an explanatory diagram of a first example of the conventional interpolation processing, and FIG. 8F is a second illustration of the conventional interpolation processing. It is explanatory drawing of the example of. FIG. 9 is an explanatory diagram of image reading according to the first embodiment, and corresponds to FIG. 8C.

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 direction indicated by Z and -Z or the indicated side is defined as the front side, the rear side, the right side, the left side, the upper side, the lower side, or the front side, the rear side, the right side, the left side, the upper side, and the lower side, respectively.
In the figure, “•” in “○” means an arrow heading 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 a first embodiment.
In FIG. 1, a copier U as an example of an image forming apparatus according to a first exemplary embodiment of the present invention is an example of a recording unit, and includes a printer unit U1 as an example of an image recording apparatus. A scanner unit U2 as an example of a reading unit and an example of an image reading device is supported on the upper portion of the printer unit U1. An auto feeder U3 as an example of a document transport device is supported on the upper portion of the scanner unit U2. The scanner unit U2 of the first embodiment supports a user interface U0 as an example of an input unit. The user interface U0 can be operated by the operator by inputting the user interface U0.

  A document tray TG1 as an example of a medium container is disposed on the upper part of the auto feeder U3. A plurality of documents Gi to be copied can be stacked and stored in the document tray TG1. A document discharge tray TG2 as an example of a document discharge unit is formed below the document tray TG1. A document transport roll U3b is disposed between the document tray TG1 and the document discharge tray TG2 along the document transport path U3a.

  A platen glass PG as an example of a transparent document table is disposed on the upper surface of the scanner unit U2. In the scanner unit U2 of the first embodiment, a reading unit U2a as an example of a reading unit is disposed below the platen glass PG. The reading unit U2a according to the first embodiment is supported so as to be movable in the left-right direction as an example of the sub-scanning direction along the lower surface of the platen glass PG. The reading unit U2a normally stops at the initial position indicated by the solid line in FIG. Note that the reading unit U2a is electrically connected to the image processing unit GS.

FIG. 2 is an explanatory diagram of a main part of an image recording unit according to the first embodiment.
The image processing unit GS is electrically connected to the writing circuit DL of the printer unit U1. The writing circuit DL is electrically connected to an exposure apparatus ROS as an example of a latent image forming apparatus.
The exposure apparatus ROS according to the first embodiment is configured to be able to output laser beams Ly, Lm, Lc, and Lk corresponding to colors Y, M, C, and K as an example of writing light. The exposure apparatus ROS is configured to be able to output laser beams Ly to Lk according to signals input from the writing circuit DL.
In FIG. 1, photosensitive members PRy, PRm, PRc, and PRk, which are examples of image carriers, are disposed above the exposure apparatus ROS. In FIG. 1 and FIG. 2, writing regions Q1y, Q1m, Q1c, and Q1k are configured by regions where the respective photoconductors PRy to PRk are irradiated with laser beams Ly to Lk.

Charging rolls CRy, CRm, CRc, and CRk, which are examples of chargers, are disposed upstream of the writing areas Q1y to Q1k with respect to the rotation direction of each of the photoconductors PRy, PRm, PRc, and PRk. The charging rolls CRy to CRk of Example 1 are supported so as to be driven to rotate in contact with the photoreceptors PRy to PRk.
Developing devices Gy, Gm, Gc, and Gk are disposed on the downstream side of the writing areas Q1y to Q1k with respect to the rotation direction of the photosensitive members PRy to PRk. Development regions Q2y, Q2m, Q2c, and Q2k are configured by regions where the photoconductors PRy to PRk and the developing devices Gy to Gk face each other.

Primary transfer rolls T1y, T1m, T1c, and T1k as an example of a primary transfer unit are disposed on the downstream side of the developing devices Gy to Gk with respect to the rotation direction of the photosensitive members PRy to PRk. The primary transfer regions Q3y, Q3m, Q3c, and Q3k are configured by regions where the photoconductors PRy to PRk and the primary transfer rolls T1y to T1k face each other.
Photoreceptor cleaners CLy, CLm, CLc, and CLk as an example of an image carrier cleaner are disposed downstream of the primary transfer rolls T1y to T1k with respect to the rotation direction of the photoreceptors PRy to PRk. .

  A toner image as an example of a visible image by the Y-color photoconductor PRy, the charging roll CRy, the exposure device ROS that outputs the Y-color laser beam Ly, the developing device Gy, the primary transfer roll T1y, and the photoconductor cleaner CLy. A Y-color image forming unit Uy as an example of a Y-color visible image forming apparatus according to the first embodiment is configured. Similarly, each photoconductor PRm, PRc, PRk, charging roll CRm, CRc, CRk, exposure device ROS, developing device Gm, Gc, Gk, primary transfer roll T1m, T1c, T1k, photoconductor cleaner CLm, CLc, CLk. Thus, the M, C, and K color image forming portions Um, Uc, and Uk are configured.

Above the photoconductors PRy to PRk, a belt module BM as an example of an intermediate transfer device is disposed. The belt module BM has an intermediate transfer belt B as an example of an intermediate transfer member. The intermediate transfer belt B is composed of an endless belt-like member.
The intermediate transfer belt B according to the first exemplary embodiment includes a belt driving roll Rd as an example of a driving member, a tension roll Rt as an example of a stretching member, a walking roll Rw as an example of a member that corrects a deviation, and a driven It is rotatably supported by an idler roll Rf as an example of a member, a backup roll T2a as an example of a counter member in the secondary transfer region, and primary transfer rolls T1y, T1m, T1c, and T1k.

A secondary transfer roll T2b as an example of a secondary transfer member is disposed at a position facing the backup roll T2a across the intermediate transfer belt B. In the first embodiment, the backup roll T2a is grounded, and a secondary transfer voltage having a polarity opposite to the toner charging polarity is applied from the power supply circuit E to the secondary transfer roll T2b. The backup roll T2a and the secondary transfer roll T2b constitute the secondary transfer device T2 of the first embodiment. Further, the secondary transfer region Q4 is constituted by the region where the secondary transfer roll T2b and the intermediate transfer belt B are in contact with each other.
A belt cleaner CLb is disposed on the downstream side of the secondary transfer region Q4 with respect to the rotation direction of the intermediate transfer belt B as an example of an intermediate transfer member cleaner.
The primary transfer rolls T1y to T1k, the intermediate transfer belt B, the secondary transfer unit T2, and the like constitute a transfer device T1 + T2 + B of the first embodiment. The image recording units Uy to Uk + T1 + T2 + B of the first embodiment are configured by the image forming units Uy to Uk and the transfer device T1 + T2 + B.

In FIG. 1, three pairs of left and right guide rails GR as an example of a guide member are provided below the image forming units Uy to Uk. On each guide rail GR, paper feed trays TR1 to TR3, which are examples of medium accommodating portions, are supported so as to be able to enter and exit in the front-rear direction. Recording sheets S as an example of a medium are accommodated in the paper feed trays TR1 to TR3.
A pickup roll Rp as an example of a take-out member is disposed on the upper right side of the paper feed trays TR1 to TR3. A separating roll Rs as an example of a separating member is disposed downstream of the pickup roll Rp with respect to the conveyance direction of the recording sheet S. As an example of a medium transport path, a paper feed path SH1 extending upward is formed on the downstream side of the separation roll Rs with respect to the transport direction of the recording sheet S. A plurality of transport rolls Ra as an example of a transport member is disposed in the paper feed path SH1.

In the sheet feeding path SH1, a registration roll Rr as an example of a conveyance timing adjusting member is disposed on the upstream side of the secondary transfer region Q4.
A fixing device F is disposed on the downstream side of the secondary transfer region Q4 with respect to the conveyance direction of the sheet S. The fixing device F includes a heating roll Fh as an example of a fixing member for heating and a pressure roll Fp as an example of a fixing member for pressure. A fixing region Q5 is constituted by a contact region between the heating roll Fh and the pressure roll Fp.
Above the fixing device F, a paper discharge path SH2 as an example of a transport path is disposed. A paper discharge tray TRh as an example of a medium discharge unit is formed on the upper surface of the printer unit U1. The paper discharge path SH2 extends toward the paper discharge tray TRh. A paper discharge roll Rh, which is an example of a medium transport member, is disposed at the downstream end of the paper discharge path SH2.

(Description of image forming operation)
In the copying machine U according to the first embodiment having the above-described configuration, when the operator places a document Gi on the platen glass PG by hand, the reading unit U2a moves in the horizontal direction from the initial position, The document Gi on the platen glass PG is scanned while being exposed. Further, when the original Gi is automatically conveyed and copied using the auto feeder U3, the reading unit U2a moves from the initial position to the original reading position indicated by the broken line in FIG. 1 and stops. To do. The plurality of documents Gi stored in the document tray TG1 are sequentially conveyed to and passed through the document reading position on the platen glass PG, and are discharged to the document discharge tray TG2. Accordingly, each document Gi that sequentially passes through the reading position on the platen glass PG is exposed and scanned by the stopped reading unit U2a. The reflected light from the document Gi is received by the reading unit U2a. The reading unit U2a converts the reflected light of the received document Gi into an electric signal.

The image processing unit GS receives an electrical signal output from the reading unit U2a. The image processing unit GS converts the electrical signals of the R, G, and B color images read by the reading unit U2a into the image information of yellow Y, magenta M, cyan C, and black K for forming a latent image. The image processing unit GS outputs the converted image information to the writing circuit DL of the printer unit U1. Note that the image processing unit GS outputs image information of only black K to the writing circuit DL when the image is a monochrome image, so-called monochrome.
The writing circuit DL outputs a control signal corresponding to the input image information to the exposure apparatus ROS. The exposure apparatus ROS outputs laser beams Ly to Lk according to the control signal.

  Each of the photoconductors PRy to PRk is driven to rotate when image formation is started. A charging voltage is applied from the power supply circuit E to the charging rolls CRy to CRk. Therefore, the surfaces of the photoconductors PRy to PRk are charged by the charging rolls CRy to CRk. Electrostatic latent images are formed on the surfaces of the charged photoreceptors PRy to PRk by the laser beams Ly to Lk in the writing areas Q1y to Q1k. The electrostatic latent images on the photoconductors PRy to PRk are developed into toner images as an example of visible images by the developing devices Gy, Gm, Gc, and Gk in the development areas Q2y to Q2k.

The developed toner image is conveyed to primary transfer regions Q3y, Q3m, Q3c, and Q3k that are in contact with an intermediate transfer belt B as an example of an intermediate transfer member. In the primary transfer regions Q3y, Q3m, Q3c, and Q3k, a primary transfer voltage having a polarity opposite to the charging polarity of the toner is applied from the power supply circuit E to the primary transfer rolls T1y to T1k. Accordingly, the toner images on the photoconductors PRy to PRk are transferred to the intermediate transfer belt B by the primary transfer rolls T1y to T1k. In the case of a multi-color toner image, the downstream toner image is transferred so as to overlap the toner image transferred to the intermediate transfer belt B in the upstream primary transfer region.
Residues and deposits on the photoconductors PRy to PRk after the primary transfer are cleaned by the photoconductor cleaners CLy to CLk. The cleaned surfaces of the photoconductors PRy to PRk are recharged by the charging rolls CRy to CRk.
The single-color or multicolor toner images transferred onto the intermediate transfer belt B by the primary transfer rolls T1y to T1k in the primary transfer areas Q3y to Q3k are conveyed to the secondary transfer area Q4.

The sheet S on which an image is recorded is taken out by the pickup rolls Rp of the paper feed trays TR1 to TR3 to be used. The sheets S picked up by the pick-up roll Rp are separated one by one by the rolls Rs when a plurality of sheets S are picked up. The sheet S separated by the separating roll Rs is conveyed through the sheet feeding path SH1 by the conveying roll Ra. The sheet S conveyed through the sheet feeding path SH1 is sent to the registration roll Rr.
The registration roll Rr conveys the sheet S to the secondary transfer area Q4 at the same time when the toner image formed on the intermediate transfer belt B is conveyed to the secondary transfer area Q4. A secondary transfer voltage having a polarity opposite to the charging polarity of the toner is applied to the secondary transfer roll T2b by the power supply circuit E. Therefore, the toner image on the intermediate transfer belt B is transferred from the intermediate transfer belt B to the sheet S.

The intermediate transfer belt B after the secondary transfer is cleaned of deposits and the like adhering to the surface by the belt cleaner CLb.
The recording sheet S on which the toner image has been secondarily transferred is heated and fixed when passing through the fixing region Q5.
The recording sheet S on which the image is fixed is conveyed through the paper discharge path SH2. The sheet S conveyed through the paper discharge path SH2 is discharged to the paper discharge tray TRh by the paper discharge roll Rh.

(Description of image reading device)
FIG. 3 is a perspective view of the image reading apparatus and the opening / closing member according to the first embodiment.
In FIG. 3, a scanner unit U2 as an example of an image reading apparatus has a case 1 as an example of a housing. On the upper surface of the case 1, a glass support port 1a as an example of an opening is formed. The glass support port 1a is formed in a rectangular shape that is long in the left-right direction. A plate-like partition portion 2 extending in the front-rear direction is formed on the left portion of the glass support port 1a. The partition 2 partitions the glass support port 1 into a manual reading port 1a1 on the right side and an automatic reading port 1a2 on the left end side. Therefore, each reading port 1a1, 1a2 is configured in a rectangular shape.

FIG. 4 is an explanatory diagram of the image reading apparatus according to the first embodiment.
3 and 4, a manual reading port 1a1 supports a reading glass 3 as an example of a first document table. The reading glass 3 of Example 1 is formed of a transparent flat glass. The reading glass 3 supports a medium on which an image is recorded, that is, a so-called document Gi. The reading glass 3 is formed on the basis of a preset maximum size of the original that can be read. In the first embodiment, the standard size A3 is set as an example of the maximum readable document size, that is, the maximum readable document size. That is, the reading glass 3 according to the first embodiment is formed in a size in which the left-right direction corresponds to the long side of A3 size and the front-back direction corresponds to the short side of A3 size.

  Behind the reading glass 3, a plate-like rear aligning portion 4 extending in the left-right direction is supported. The rear alignment portion 4 is disposed along the rear end of the reading glass 3. The rear aligning portion 4 is disposed in a state having a step above the upper surface of the reading glass 3. Therefore, it is possible to align the position of the rear end of the document Gi by bringing the rear edge of the document Gi into contact with the rear aligning portion 4. In addition, a plate-like left alignment portion 6 extending in the front-rear direction is supported on the left side of the reading glass 3, that is, on the right portion of the partition portion 2. The left alignment portion 6 is disposed along the left end of the reading glass 3. The left alignment portion 6 is formed in a plate shape having a step above the upper surface of the reading glass 3. Therefore, the left edge of the document Gi can be brought into contact with the left alignment unit 6 to align the left edge of the document Gi.

3 and 4, a reading glass 11 as an example of a second document table is supported by the automatic reading port 1a2. The reading glass 11 of Example 1 is formed of a transparent flat glass. Note that the length of the reading glass 11 in the front-rear direction is formed based on a preset size of a maximum readable document. In Example 1, the length of the reading glass 11 in the front-rear direction is formed corresponding to the length of the short side of A3 size. The reading glass 3 and the reading glass 11 constitute a platen glass PG as an example of a support surface of the first embodiment.
A document guide 12 extending in the front-rear direction is supported on the right side of the reading glass 11, that is, on the left side of the partition 2, as an example of a document guide member. The document guide 12 is formed in a shape in which the height of the left end is set lower than the upper surface of the reading glass 11 and is inclined upward as it advances to the right side.

1 and 4, a reading unit U2a is arranged below the platen glass PG.
The reading unit U2a includes a CIS (Contact Image Sensor) unit 21 as an example of a reading member, and a carriage 22 as an example of a moving unit that supports the CIS unit 21.
The CIS unit 21 extends in the main scanning direction as an example of the second direction. In the first embodiment, the main scanning direction corresponds to the front-rear direction. The CIS unit 21 supports a lamp 21a as an example of a light source unit. The lamp 21 a irradiates reading light, so-called illumination light, toward the document Gi on the upper surface of the reading glass 3.

Inside the CIS unit 21, a light receiving unit 21b that receives the illumination light reflected by the document Gi and reads an image is supported. The light received by the light receiving unit 21b is processed into an electrical signal by the substrate 21c and sent to the image processing unit GS. The CIS is conventionally known, and for example, various configurations described in Japanese Patent Application Laid-Open Nos. 2007-13309 and 2012-151568 can be employed.
The CIS unit 21 of the first embodiment is provided with four contact portions 21d protruding upward at both front and rear ends. The contact portion 21 d has an upper surface formed in an arc shape, and is configured to reduce frictional resistance even when the contact portion 21 d moves while contacting the lower surface of the reading glass 3.

The CIS unit 21 is supported so as to be movable in the vertical direction with respect to the carriage 22, and the CIS unit 21 is biased upward by a spring 24 as an example of a pressing member. Therefore, the CIS unit 21 pressed by the spring 24 is held in a state where the contact portion 21 d is pressed against the lower surface of the reading glass 3. That is, the distance between the lamp 21a and the light receiving unit 21b of the CIS unit 21 and the document Gi on the upper surface of the reading glass 3 is held at a preset interval.
The carriage 22 of the first embodiment is supported by a guide shaft as an example of a guide member of a unit (not shown) so as to be movable in the sub-scanning direction as an example of the first direction. Further, a belt as an example of a moving member of a unit (not shown) is connected to the carriage 22 and is moved in the sub-scanning direction by forward / reverse rotation of the belt. Therefore, the reading unit U2a according to the first embodiment moves based on the detection signals of a plurality of sensors arranged below the platen glass PG. When reading the document Gi conveyed by the auto-feeder U3, the reading unit U2a moves to the position indicated by the solid line in FIG. 1, and when reading the document Gi supported on the upper surface of the reading glass 3, the broken line in FIG. The reading unit U2a moves to the right from the reading start position shown.

FIG. 5 is an explanatory diagram of a main part of the light source unit according to the first embodiment.
The lamp 21a according to the first embodiment includes a red LED 31 as an example of a first light source member, a green LED 32 as an example of a second light source member, and a blue LED 33 as an example of a third light source member. The red LED 31 emits red light as an example of the first color light. The green LED 32 emits green light as an example of the second color light. The blue LED 33 emits blue light as an example of the third color light. Light emitted from each of the LEDs 31 to 33 is applied to the document Gi in a line along the main scanning direction via a ride guide 34 as an example of a light guide.
Reflected light from the document Gi is received by the light receiving unit 21b through the lens 36. The light receiving unit 21b according to the first embodiment includes a one-line sensor in which light receiving elements are arranged in a line in the main scanning direction.

FIG. 6 is an explanatory diagram of a time chart of light source control according to the first embodiment.
In FIG. 5, drive circuits 41, 42, and 43 are connected to the LEDs 31 to 33, respectively. Each drive circuit 41-43 is controlled by the light source control means C1 of the control part C. The light source control unit C1 includes a reference pulse generation unit C1a, a first light control unit C1b, a second light control unit C1c, and a third light control unit C1d as an example of a reference signal generation unit. . The light source control means C1 controls the light emission of each LED 31-33. The light source control unit C1 according to the first embodiment causes the red LED 31, the green LED 32, and the blue LED 33 to repeatedly emit light in order based on a pulse signal as an example of a reference signal.
The reference pulse generator C1a generates a reference pulse as an example of a reference signal. In FIG. 6, the reference pulse generation means C1a according to the first embodiment generates a pulse signal 46 as an example of the reference signal with a preset time interval t1.

  The first light control means C1b controls the red LED 31 via the drive circuit 41 to control the irradiation of red light. The first light control means C1b according to the first embodiment applies a first waiting time preset from the pulse signal when the red light is emitted, that is, when the pulse signal is generated after the previous blue light is emitted. At the light emission start timing T1 after the lapse of ta, the red LED 31 is controlled to emit red light. The first standby time ta is as large as possible based on the pulse interval t1 and the red light irradiation period tb so that the red light irradiation period is as close as possible to the next green light irradiation period. Is set. In addition, the first light control unit C1b according to the first embodiment increases the light emission amount and the light emission intensity per unit time and shortens the irradiation period tb as compared with the related art. As an example, the current value of the LED related to the amount of light is conventionally 300 mA and irradiation is performed for a period of 50 μs, whereas in Example 1, it is set to 500 mA and 30 μs. Therefore, in the first embodiment, the total light amount (= current value × period) received by the light receiving unit 21b is set to be the same as the conventional one.

  The second light control means C1c controls the green LED 32 via the drive circuit 42 to control the green light irradiation. When the second light control unit C1c of the first embodiment emits green light, that is, when a pulse signal is generated after the previous red light irradiation, a second standby time set in advance from the pulse signal. At the light emission start time T3 after tc has elapsed, the green LED 32 is controlled to emit green light. The second standby time tc is set to a value as small as possible so that the green light irradiation period is as close as possible to the previous red light irradiation period tb. Further, in the second light control unit C1c of the first embodiment, the irradiation period td is set as long as possible in order to approach the irradiation period of the previous red light and the next blue light. And in the 2nd light control means C1c of Example 1, according to the irradiation period td becoming long, the total light reception amount in the light-receiving part 21b does not exceed the capacity | capacitance on the performance of the light-receiving part 21b. For this reason, the amount of light at the time of irradiation, that is, the value of the current supplied to the LED 32 is reduced compared to the conventional case.

  As an example, in Example 1, the current value is set to 100 mA, and the irradiation period td is set to 150 μs. Accordingly, in the first embodiment, the total light amount (= current value × period) received by the light receiving unit 21b is set to be the same as that of red light or a conventional configuration. The irradiation period td is set so that the center of the green light period is the center of the red light and the blue light. That is, in Example 1, the period td during which the green light is irradiated is set so as not to be biased to either the red light side or the blue light side. Therefore, in the first embodiment, the time from the red light emission end timing T2 to the green light emission start timing T3 matches the time from the green light emission end timing T4 to the blue light emission start timing T5. Is set to

  The third light control means C1d controls the blue LED 33 via the drive circuit 43 to control the blue light irradiation. The third light control means C1d according to the first embodiment applies a third waiting time preset from the pulse signal when the blue light is emitted, that is, when the pulse signal is generated after the previous green light irradiation. At the light emission start time T5 after elapse of te, the blue LED 33 is controlled to emit blue light. The third standby time te is set as small as possible so that the blue light irradiation start timing T5 is as close as possible to the previous green light irradiation end timing T4. Further, the third light control unit C1d of the first embodiment increases the light amount and shortens the irradiation period tf as compared with the conventional case, as in the case of red light. In the first embodiment, as an example, similarly to red light, blue light is also set to have a current value of 500 mA and an irradiation period tf of 30 μs.

FIG. 7 is an explanatory diagram of a read image correction process according to the first embodiment.
The reading unit C2 includes an interpolation processing unit C2a, and reads an image of the document Gi based on the light reception result of the light receiving unit 21b. The interpolation processing unit C2a of the reading unit C2 according to the first embodiment performs a correction process corresponding to a process of interpolating the deviation of the read position based on the read R, G, and B images. In FIG. 7, in the first embodiment, as an example, for R: red and B: blue images, 80% of the read image is assigned to the position of G: green image, and R, B images are assigned. A process of assigning 20% to the read position is performed. This process is not performed for green images.

(Function of the image reading apparatus of the first embodiment)
In the scanner unit U2 of the first embodiment having the above-described configuration, when an image of the document Gi is read, the image is read while the document Gi moves relatively in the sub-scanning direction with respect to the reading unit U2a. . At this time, R, G, and B light are sequentially irradiated onto one column and one line in the main scanning direction of the document Gi, and an image for one line is read.

FIG. 8 is an explanatory diagram of conventional image reading, FIG. 8A is a time chart of conventional light control, FIG. 8B is a black line image as an example of a document image, and FIG. 8C is a document image of FIG. 8B. 8D is an explanatory diagram of the read image of the original image of FIG. 8B, FIG. 8E is an explanatory diagram of a first example of the conventional interpolation processing, and FIG. 8F is a second illustration of the conventional interpolation processing. It is explanatory drawing of the example of.
A conventional image reading apparatus has a configuration in which white light is irradiated and an image is read using light receiving elements for three lines of R, G, and B, so-called three line sensors. However, since the configuration of the sensor is high, a one-line sensor is also used for cost reduction. When a conventional one-line sensor is used, as shown in FIG. 8, R, G, and B light is emitted at the same timing with reference to a pulse signal.

In such a configuration, when a black line as shown in FIG. 8B is read, as shown in FIG. 8C, there is a positional deviation of the read signals of R, G, B. Therefore, when these are combined, as shown in FIG. 8D, in the full-color read image, thin lines of red and blue are generated on both sides of the black line in the sub-scanning direction, and so-called color shift occurs. In order to reduce this, correction processing may be performed before the R, G, B read images are combined.
Note that color misregistration includes color misregistration and color blurring. Here, for example, it is conceivable to perform correction in order to suppress the positional deviation of the color, but when the original positional deviation amount is large, in order to suppress the influence of the positional deviation, It is conceivable to increase the contribution ratio of the pixels. In that case, it is necessary to change the contribution ratio of the preceding and succeeding pixels between the respective colors, so that a shift in color blur occurs. Further, even if this blur condition is different, a new color shift may occur. This will be specifically described below.

  In FIG. 8E, since the read value of R does not exist at the position where the reading of G is performed, a process of assigning the read value of R to the position of G where reading is not performed, so-called interpolation processing is performed. Sometimes. At this time, in the conventional configuration, since the center position 01 of R and the center position 02 of G are separated from each other, if all of the R reading values are assigned to the G position, an image at the R position exists. On the other hand, since a position shift occurs, a part of the position needs to be assigned to the R position 01. Therefore, as a result, the ratio assigned to the position 02 of G decreases, and the resolving power decreases (color is blurred). In particular, the difference in resolving power from the G reading value (shift in color blur) increases. With respect to B as well, there is a problem in that the difference in resolving power between the reading value of G and the reading becomes large.

In the correction process shown in FIG. 8E, the R and B images are matched with G. As a result, the R and B images are blurred, and only G is not blurred. In this state, the coloring of the edge portion as shown in FIG. 8D still occurs. On the other hand, as shown in FIG. 8F, in order to blur the G image in accordance with R and B, a process of assigning the G read value to the R and B positions 01 and 03 is also conceivable. However, in the process shown in FIG. 8F, the difference in resolution is reduced, but the resolution of G is also reduced, and there is a problem that the overall resolution is reduced (the color is blurred as a whole).
As in the technique described in Patent Document 1, in the configuration in which the irradiation period is changed for each of R, G, and B colors, the center positions 01 to 03 of R, G, and B are closer than in the case illustrated in FIG. 8A. However, the timing when the LED starts to irradiate with respect to the pulse signal is fixed, and there is a limit to how close it can be.

FIG. 9 is an explanatory diagram of image reading according to the first embodiment, and corresponds to FIG. 8C.
On the other hand, in Example 1, when light is emitted in the order of R, G, and B, the timing when the R and B colors start to emit light is made as close as possible to the G color with respect to the pulse signal. Yes. Therefore, the reading centers 51 and 53 for the R and B colors are close to the reading center 52 for the G color. In Example 1, the light emission amounts of the R color and the B color are also larger than those of the G color. Therefore, compared with the case where the light emission amount is the same as before, it is possible to make it closer to G color. Therefore, in the first embodiment, the color shifts of R, G, and B are reduced as compared with the conventional case, and the deterioration of the image quality of the read image can be reduced.
In particular, for example, when the reading cycle of one line becomes long, such as when the setting for reading normally at 600 dpi is changed to 200 dpi, the amount of color misregistration increases in the conventional configuration in which the intervals of R, G, and B are long. There is a fear. On the other hand, in Example 1, the intervals of R, G, and B are narrower than the conventional one, and the amount of color misregistration can be suppressed.

In the first embodiment, the reading center positions 51 to 53 of the R, G, and B colors are approaching, and when interpolation processing is performed for the R and B colors, as shown in FIG. Compared to this, it is possible to allocate a large percentage. Therefore, the difference in resolving power between the R color, G color, and B color can be reduced. Also, the overall resolving power can be improved as compared with the conventional case.
Furthermore, in Example 1, the G light emission intensity is set to be weaker than the R light emission intensity and the B light emission intensity. Therefore, the shape of the G light emission intensity distribution shown in FIG. 9 has a gentle mountain compared to the shapes of the R and B intensity distributions. For the R color and B color, after the interpolation process, the shape of the intensity distribution becomes gentle, and as a result, the shape of the intensity distribution of the G color is almost the same. Therefore, color misregistration is suppressed as compared with the case where the emission intensity of G color is not weaker than that of R color and B color.

(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 made in the range of the summary of this invention described in the claim. Is possible. Modification examples (H01) to (H05) of the present invention are exemplified below.
(H01) In the above-described embodiment, the copying machine U as an example of the image forming apparatus has been illustrated. However, the present invention is not limited to this, and the multifunction machine having a plurality of functions such as FAX or FAX, a printer, and a copying machine. Etc. are applicable. Further, the image forming apparatus is not limited to an electrophotographic image forming apparatus, and can be applied to an image forming apparatus of an arbitrary image forming system such as an ink jet recording system, a thermal head system, and a printing machine such as a lithograph. Further, the image forming apparatus is not limited to a multi-color developing image forming apparatus, and may be configured by a monochromatic, so-called monochrome image forming apparatus. In the above-described embodiment, the scanner unit U2 is illustrated as an example of the image reading device, and the configuration provided in the copying machine U is illustrated. Applicable.

(H02) In the above-described embodiment, the irradiation order of the colors R, G, and B is not limited to the order of R, G, and B, and can be changed to any order.
(H03) In the above embodiment, it is desirable to increase the light emission amounts of R and B and decrease the light emission amount of G, but the present invention is not limited to this. It is possible to make the light emission amounts of R and B the same as in the prior art or the same as G. In addition, the light emission amount of G can be the same as the conventional one.
(H04) In the above embodiment, the light emission periods tb and tf of R and B are preferably the same, but the characteristics such as the time lag until the light emission of the LED starts and the time during which the light emission stabilizes, individual differences, etc. It is also possible to change it according to. The same applies to the G light emission period td. The R and B light emission periods tb and tf are preferably set shorter than the G light emission period td, but may be the same.

(H05) In the above embodiment, the interpolation process is not limited to the process illustrated in the embodiment, and can be arbitrarily changed according to the design, specifications, required image quality, and the like. In addition, although it is desirable to perform the interpolation process, a configuration in which the interpolation process is not performed is also possible.

21a ... Light source part,
31 ... 1st light source member,
32. Second light source member,
33 ... Third light source member,
46 ... reference signal,
B ... Third color,
G ... second color,
Gi ... manuscript,
t1 time interval,
T3: The second color emission start time,
T4: end time of light emission of the second color,
tb: light emission period of the first color,
td: light emission period of the second color,
tf: light emission period of the third color,
C1 ... light source control means,
C2a: interpolation processing means,
R ... first color,
S ... medium
U: Image forming apparatus,
U2 ... Image reading device,
U2a ... reading unit,
Uy to Uk + T1 + T2 + B: Image recording unit.

Claims (5)

A light source unit that emits light toward a document on which an image is recorded, the first light source member that irradiates light of a first color, and light of a second color different from the first color. The light source unit including: a second light source member that irradiates; and a third light source member that emits light of a third color different from the first color and the second color;
A reading unit that moves relative to a document in a first direction set in advance and reads the document, and receives a light reflected from the document in the first direction. The reading units arranged side by side so as to receive light along the intersecting second direction;
Light source control means for controlling the light emission of each light source member, and sequentially repeating the first color, the second color, and the third color based on a reference signal output at a preset time interval The light emission of the first color is controlled to be close to the light emission start time of the second color, and the light emission of the third color is controlled to be close to the light emission end time of the second color. The light source control means;
An image reading apparatus comprising:   2. The image reading apparatus according to claim 1, wherein the light emission period of the second color is set longer than the light emission periods of the first color and the third color.   The image reading apparatus according to claim 2, wherein the emission intensity of the first and third colors is higher than the emission intensity of the second color. Based on a temporal shift between the first color and the second color, interpolation processing of the first color at the position of the second color is performed, and the third color and the second color are performed. Interpolation processing means for performing interpolation processing of the third color at the position of the second color based on temporal deviation from the color of
The image reading apparatus according to claim 1, further comprising: An image reading device according to any one of claims 1 to 4, which reads an image from a medium;
An image recording unit for recording an image on a medium based on an image read by the image reading device;
An image forming apparatus comprising:

Images