JP2014138236A - Image reader and image formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve color shift even when reading sections with wide interval are used.SOLUTION: An image reader (U2) includes: a reading member (CCD) having a first reading part (31) for reading a first color, and second reading parts (32) arranged at positions spaced apart from the first reading part (31) in a direction corresponding to the relative movement, and reading a second color different from the first color; and an optical system (A) arranged on the optical path between the reading position and the reading member (CCD), and having an optical member (11) for focusing the reflection light (12) from the reading position (Pr) depending on the interval of the first reading part (31) and second reading parts (32).

Description

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

  In the conventional image reading apparatus, the techniques described in the following Patent Documents 1 and 2 are conventionally known as techniques relating to reading of RGB three-color images.

In JP-A-1-95662 as Patent Document 1, a blue (B color) image at the position A of the glass table (2) is read by the sensor (6c), and the downstream side in the sub-scanning direction from the position A. The green (G color) image at the position O shifted to is read by the sensor (6b), and the red (R color) image at the position B shifted from the position O to the downstream side in the sub-scanning direction is read by the sensor (6b). ) Describes the technology to be read. In the technology described in Patent Document 1, color image information is read by superimposing images read at positions (A, O, B) shifted in the sub-scanning direction.
In the technique described in Patent Document 1, each position (A, O, B) is handled in order to cope with a shift in the distance between the positions (A, O, B) due to the bending of the glass table (2) and the ups and downs of the document (1). , O, B), by arranging the parabolic mirror (3), the cylindrical lens (21), and the Fresnel lens (31), the principal ray of the light flux corresponding to the line sensors (6a to 6c) The document surface (1) is telecentric with respect to the sub-scanning direction, that is, the principal ray is orthogonal to the document surface (1).

  Japanese Patent Application Laid-Open No. 2002-209056 as Patent Document 2 discloses that a light beam (A) collected by an imaging unit is separated into three colors of RGB by a diffraction grating (1), and then an interline correction prism ( 2) describes a technique for equalizing the line spacing of the monolithic three-line sensor (3) by shifting the imaging position of only the primary light (R).

JP-A-1-95662 (second page, lower right column, first line to third page, upper right column, fifth line, FIGS. 1 to 4) JP 2002-209056 ("0025" to "0026", FIG. 1)

  It is a technical object of the present invention to improve color misregistration even when reading units having a wide interval are used.

In order to solve the technical problem, an image reading apparatus according to claim 1 is provided.
A moving member that relatively moves a medium having an image formed on a surface thereof and a reading position that is opposed to the medium and receives reflected light from the image;
A reading member that reads the reflected light, and is spaced apart from the first reading unit that reads the first color in the image along the direction corresponding to the relative movement with respect to the first reading unit. A second reading unit arranged at a position and reading a second color different from the first color;
An optical element disposed on an optical path between the reading position and the position where the reading member is located, an imaging element for converging light toward the first reading unit and the second reading unit; An optical member disposed on an optical path between the imaging element and a reading position, wherein the reflected light is applied to the imaging element in accordance with an interval between the first reading unit and the second reading unit. The optical member to converge with respect to the optical system,
It is provided with.

  In the specification and claims of the present application, “converging” is used to mean “changing the incident light in the direction of convergence”, and is not limited to “when converging to the focal point”. , "When diverging incident light is converted into parallel light" and "when diverging angle of incident light is reduced".

According to a second aspect of the present invention, in the image reading apparatus according to the first aspect,
The optical member configured by a transparent member having an incident surface on which diverged reflected light from a reading position is incident and an output surface on which the incident light is refracted into parallel light and output;
It is provided with.

According to a third aspect of the present invention, in the image reading device according to the second aspect,
The focal position of the transparent member is set to the reading position.

According to a fourth aspect of the present invention, in the image reading apparatus according to the first aspect,
The optical member having a reflecting surface that reflects the reflected reflected light from the reading position as parallel light;
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,
An image recording apparatus for recording an image read by the image reading apparatus on a medium;
It is provided with.

According to the first and fifth aspects of the present invention, color misregistration can be improved even when a reading unit having a wide interval is used as compared with the case where the configuration of the present invention is not provided.
According to the second aspect of the invention, the reflected light can be refracted by the optical member and converged according to the interval between the first reading unit and the second reading unit.
According to the third aspect of the present invention, an image at a common reading position can be read by each reading unit.
According to the fourth aspect of the invention, the reflected light can be reflected by the optical member and converged according to the interval between the first reading unit and the second reading unit.

FIG. 1 is an explanatory diagram of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is an explanatory diagram of an image reading apparatus according to the first exemplary embodiment. FIG. 2A is an overall view of the image reading apparatus, FIG. 2B is an enlarged view of a reading position, and FIG. 2C is an enlarged view of an imaging member. 3A and 3B are explanatory diagrams of a conventional color image reading method. FIG. 3A is an overall view of an image reading apparatus, FIG. 3B is an enlarged view of a reading position, and FIG. 3C is an enlarged view of an imaging member. FIG. 4 is an explanatory diagram of an image reading apparatus according to the second embodiment corresponding to FIG. 2 of the first embodiment, FIG. 4A is an overall view of the image reading apparatus, and FIG. 4B is an enlarged view of a reading position. FIG. 5 is an explanatory diagram of setting of the reading position in the modified example.

Next, examples as specific examples of embodiments of the present invention will be described with reference to the drawings. However, 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 explanatory diagram of an image forming apparatus according to a first embodiment of the present invention.
In FIG. 1, a copier U as an example of an image forming apparatus according to the first exemplary embodiment 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 path U3a as an example of a medium transport path is formed between the document tray TG1 and the document discharge tray TG2. A document transport roll U3b, which is an example of a medium transport member, is disposed in 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 optical system A is disposed below the platen glass PG. The optical system A for reading in Example 1 is supported so as to be movable in the left-right direction along the lower surface of the platen glass PG. The reading optical system A is normally stopped at the initial position shown in FIG.
An imaging member CCD is disposed on the left side of the optical system A for reading. An image processing unit GS is electrically connected to the imaging member CCD.
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.

A photosensitive drum PR, which is an example of an image carrier, is disposed below the exposure apparatus ROS. The photosensitive drum PR rotates in the direction of the arrow Ya.
On the photosensitive drum PR, a charging roll CR, which is an example of a charger, is disposed opposite to the charging area Q0. A charging voltage is applied from the power supply circuit E to the charging roll CR. The power supply circuit E is controlled by a controller C as an example of a control unit. The controller C performs various controls by transmitting and receiving signals to and from the image processing unit GS and the writing circuit DL.
In the writing area Q1 set on the downstream side of the charging area Q0 with respect to the rotation direction of the photosensitive drum PR, a laser beam L as an example of writing light from the exposure device ROS is formed on the surface of the photosensitive drum PR. Is irradiated.
In the developing area Q2 set on the downstream side of the writing area Q1 with respect to the rotation direction of the photosensitive drum PR, the developing device G is disposed to face the surface of the photosensitive drum PR.

On the left side of the developing device G, a cartridge K as an example of a developer container is disposed. The cartridge K is detachably attached to a cartridge holder KS as an example of a container support member. Below the cartridge holder KS, a reserve tank RT as an example of a temporary storage portion for the developer is disposed. The reserve tank RT and the developing device G are connected by a developer transport device GH.
A transfer area Q3 is set on the downstream side of the development area Q2 with respect to the rotation direction of the photosensitive drum PR.

Under the printer unit U1, paper feed trays TR1 to TR4 as examples of a medium container are detachably supported. Sheets T as an example of a medium are accommodated in the sheet feed trays TR1 to TR4.
A pickup roll Rp as an example of a medium take-out member is disposed on the upper left side of the paper feed trays TR1 to TR4. On the left side of the pick-up roll Rp, a separating roll Rs as an example of a separating member is disposed.
On the left side of each of the paper feed trays TR1 to TR4, a medium transport path SH1 extending upward is formed. A plurality of transport rolls Ra as an example of a medium transport member are arranged in the transport path SH1.
A registration roll Rr as an example of a feeding member is disposed downstream of the conveyance roll Ra and upstream of the transfer region Q3 with respect to the conveyance direction of the sheet S.

  On the left side of the cartridge holder KS or the like, a manual feed tray TRt, which is an example of a medium storage container and is an example of a manual feed unit, is installed. The manual feed tray TRt according to the first exemplary embodiment is supported to be rotatable about the rotation center TRt0. Therefore, the manual feed tray TRt is configured to be movable between a housed position shown by a solid line in FIG. 1 and a feedable position shown by a one-dot chain line in FIG. When the manual feed tray TRt according to the first embodiment is moved to the stored position, a part TRt1 of the manual feed tray TRt is accommodated in a state of entering the lower side of the cartridge holder KS and the left side of the reserve tank RT. . Accordingly, the entire copying machine U is reduced in capacity and reduced in size.

In the transfer area Q3, a transfer unit TU, which is an example of a transfer device and an example of a medium transport device, is disposed below the photosensitive drum PR. The transfer unit TU includes an endless transfer belt TB as an example of a medium transport member.
The transfer belt TB is rotatably supported by a driving roll Rd as an example of a driving member and a driven roll Rf as an example of a driven member.
Inside the transfer belt TB, a transfer roll TR as an example of a transfer device is supported. The transfer roll TR is disposed to face the photosensitive drum PR with the transfer belt TB interposed therebetween. Therefore, the transfer region Q3 is constituted by the region where the transfer roll TR and the photosensitive drum PR face each other. A transfer voltage is applied from the power supply circuit E to the transfer roll TR.

A peeling claw SC as an example of a medium peeling member is disposed at the right end of the transfer belt TB. Below the peeling claw SC, a belt cleaner CLb as an example of a cleaner of the transfer device is disposed to face the surface of the transfer belt TB.
Note that a drum cleaner CLp, which is an example of an image carrier cleaner, is disposed on the downstream side of the transfer region Q3 with respect to the rotation direction of the photosensitive drum PR so as to face the surface of the photosensitive drum PR. Yes.

A fixing device F is disposed on the right side of the transfer unit TU. The fixing device F includes a heating roll Fh as an example of a heating rotating member and a pressure roll Fp as an example of a pressing rotating member.
To the right of the fixing device F, a discharge path SH2 extending upward is connected as an example of a medium transport path.
In the discharge path SH2, as an example of a medium transport member, a transport roll Rb and a discharge roll Rh capable of transporting the medium and rotating in the forward and reverse directions are arranged.
On the upper surface of the printer unit U1, a paper discharge tray Rh as an example of a medium discharge unit is formed.

A reversing path SH3, which is an example of a medium transport path, is formed below the discharge path SH2. The reversing path SH3 according to the first embodiment branches from the discharge path SH2 and extends downward, and joins the transport path SH1 on the upstream side in the sheet transport direction from the registration roll Rr.
A gate MG as an example of a transfer direction switching member is disposed at a branch portion between the discharge path SH2 and the reversal path SH3. The gate MG of the first embodiment is formed of an elastically deformable thin film shape, so-called film. When the sheet S conveyed from the fixing device F passes through the gate MG, the gate MG is pushed by the sheet S and is elastically deformed so that the sheet S can pass through the discharge path SH2. When the sheet S is conveyed from the discharge path SH2 to the reversing path SH3, the gate MG is held in an elastically restored state, preventing the sheet S from entering the fixing device F, and the reversing path SH3. It arrange | positions so that the sheet | seat S may be guided to the side.

(Description of image forming operation)
The plurality of documents Gi stored in the document tray TG1 sequentially passes through the document reading position on the platen glass PG and is discharged to the document discharge tray TG2.
When the automatic feeder U3 is used to automatically convey and copy a document, each document that sequentially passes through the reading position on the platen glass PG with the reading optical system A stopped at the initial position. Gi is exposed.
When the operator places the document Gi on the platen glass PG by hand, the optical system A for reading moves in the left-right direction, and the document on the platen glass PG is scanned while being exposed.
The reflected light from the document Gi passes through the optical system A and is collected on the imaging member CCD. The imaging member CCD converts the reflected light of the document collected on the imaging surface into an electrical signal.

The image processing unit GS converts the read signal input from the imaging member CCD into a digital image signal and outputs it to the writing circuit DL of the printer unit U1. The writing circuit DL outputs a control signal corresponding to the input image writing signal to the exposure apparatus ROS.
The surface of the photosensitive drum PR is charged by the charging roll CR in the charging region Q0. At the latent image writing position Q1, the laser beam L output from the exposure apparatus ROS forms an electrostatic latent image on the surface of the photoconductor PR. In the developing region Q2, the developing device G develops the electrostatic latent image on the photosensitive drum PR that passes through the developing region Q2 into a toner image Tn as an example of a visible image. When the developer is consumed in the developing device G, the developer transport device GH is operated according to the consumption amount, and the developer is supplied from the cartridge K to the developing device G.

The sheets S of the respective trays TR1 to TR4 are taken out by the pickup roll Rp at a preset sheet feeding time. The sheets S picked up by the pickup roll Rp are separated one by one by the separating roll Rs when picked up in a state where a plurality of sheets S are overlapped. The sheet S that has passed the separating roll Rs is conveyed to the registration roll Rr by a plurality of conveyance rolls Ra.
The sheet S fed from the manual feed tray TRt also joins the transport path SH and is transported to the registration roll Rr.

The sheet S conveyed to the registration roll Rr is transferred from the sheet guide SG1 before transfer as an example of a guide member before transfer to the transfer area according to the timing when the toner image on the surface of the photosensitive drum PR moves to the transfer area Q3. It is transported toward Q3.
The sheet S conveyed from the registration roll Rr is supported on the surface of the transfer belt TB and passes through the transfer region Q3. The toner image Tn on the surface of the photosensitive drum PR is transferred to the sheet S passing through the transfer region Q3 by the transfer voltage applied to the transfer roll TR.
The surface of the photosensitive drum PR after passing through the transfer region Q3 is cleaned by removing residual toner by the drum cleaner CLp. The surface of the photosensitive drum PR after cleaning is recharged by the charging roll CR.

The sheet S to which the toner image Tn is transferred is peeled from the transfer belt TB by the peeling claw SC. From the transfer belt TB from which the sheet S has been peeled off, deposits such as developer and paper dust attached to the surface of the transfer belt TB are removed by the belt cleaner CLb. When the sheet S peeled from the transfer belt TB passes through the contact area between the heating roll Fh and the pressure roll Fp, the toner image is heated and pressed to be fixed.
The recording sheet S on which the toner image is fixed passes through the gate MG while being elastically deformed, and is conveyed to the discharge path SH2. The sheet S discharged to the paper discharge tray TRh is transported by the transport roll Rb and discharged to the paper discharge tray TRh by the discharge roll Rh.

  When duplex printing is performed, the trailing edge of the sheet S on which one side has been recorded is conveyed downstream by the conveyance roll Rb and the discharge roll Rh until it passes through the gate MG. When the trailing edge of the sheet S passes through the gate MG, the transport roll Rb and the discharge roll Rh rotate in the reverse direction and are transported from the discharge path SH2 toward the reversal path SH3. That is, the sheet S is so-called switched back with the conveyance direction reversed. The switched sheet S is guided by the gate MG and conveyed through the reversing path SH3. The sheet S conveyed on the reversing path SH3 joins the conveying path SH1, and is conveyed to the registration roll Rr with the front and back sides reversed. Then, an image is printed on the second surface of the sheet S in the transfer region Q3.

(Description of Image Reading Device of Example 1)
FIG. 2 is an explanatory diagram of an image reading apparatus according to the first exemplary embodiment. FIG. 2A is an overall view of the image reading apparatus, FIG. 2B is an enlarged view of a reading position, and FIG. 2C is an enlarged view of an imaging member.
In FIG. 2, in the scanner unit U <b> 2 as an example of the image reading apparatus according to the first embodiment, the platen glass PG has an automatic reading surface 1 as an example of a first support member. The automatic reading surface 1 is formed in a plate shape extending in the front-rear direction. On the left side of the automatic reading surface 1, a manual reading surface 2 as an example of a second support member is disposed. The manual reading surface 2 is formed in a plate shape corresponding to the maximum size of the document Gi that can be read by the scanner unit U2. That is, the document Gi can be supported on the upper surface of the manual reading surface 2. The platen glass PG of the first embodiment is configured by the reading surfaces 1 and 2.

  A document guide 3 as an example of a medium guide member is disposed above the automatic reading surface 1. The document guide 3 is supported by an automatic feeder U3 as an example of a moving member for automatic reading so as to be able to approach and separate from the automatic reading surface 1. On the lower surface of the document guide 3, a document guide surface 3a as an example of a medium guide portion is formed. The document guide 3 is pressed downward by a spring 4 as an example of an elastic member. Accordingly, the document guide 3 is configured to press the sheet S conveyed on the document conveyance path U3a against the automatic reading surface 1 while being guided by the document guide surface 3a.

  A reading optical system A is disposed below the platen glass PG. The optical system A for reading has an illumination unit 6 as an example of an irradiation system. The illumination unit 6 is supported so as to be movable in the left-right direction. A reading position Pr is set above the illumination unit 6. The reading position Pr according to the first exemplary embodiment moves as the illumination unit 6 moves. Note that the reading position Pr of the first embodiment is set to a linear shape extending in the front-rear direction, that is, a linear shape for one line. Further, the reading position Pr in the first embodiment is set to a height corresponding to the upper surface of the platen glass PG.

  The irradiation unit 6 includes an illumination member 7 as an example of a light source. The illumination member 7 is constituted by a lamp that outputs illumination light 7a to the reading position Pr. On the right side of the illumination member 7, an illumination mirror 8 is disposed as an example of a reflection member for illumination. The illumination mirror 8 is set to an angle that reflects the light from the illumination member 7 toward the reading position Pr. Therefore, in the illumination unit 6 according to the first embodiment, the light 7a is irradiated from the both sides in the left-right direction, that is, both the upstream side and the downstream side in the transport direction of the document Gi at the reading position Pr by the illumination member 7 and the illumination mirror 8. Is set to be. Therefore, in the scanner unit U2 according to the first embodiment, the influence of the shadow due to the unevenness of the document Gi is reduced as compared with the case where light is irradiated from one side.

A prism 11, which is an example of an optical member and an example of a transparent member, is disposed below the reading position Pr. An incident surface 11 a is formed on the upper surface of the prism 11 of the first embodiment. The incident surface 11a of Example 1 is formed in a planar shape along the left-right direction. An output surface 11 b is formed on the lower surface of the prism 11. The output surface 11b of Example 1 is configured by a convex surface facing downward.
In the prism 11 according to the first exemplary embodiment, the diverging reflected light 12 reflected from the original document Gi passing through the reading position Pr is incident from the incident surface 11a and transmitted through the inside, and the transmitted light 12 is parallel light from the output surface 11b. Thus, the thickness of the prism 11 and the outer shape of the output surface 11b are set so as to output downward. That is, the prism 11 according to the first exemplary embodiment is arranged so that the focal position of the prism lens coincides with the reading position Pr.

A first mirror 13 as an example of a reflecting member is disposed below the prism 11. The first mirror 13 is configured by a flat reflecting mirror. The first mirror 13 of the first embodiment has an inclination angle with respect to the horizontal so as to reflect the reflected light 12 from above that has been collimated by the prism 11 to the right.
A reflection unit 21 as an example of a reflection system is disposed on the right side of the irradiation unit 6. The reflection unit 21 is supported so as to be movable in the left-right direction.
The irradiation unit 6 and the reflection unit 21 are moved in the left-right direction in conjunction with a motor or a wire (not shown) as an example of a manual moving member. At this time, the reflection unit 21 moves at a moving speed that is ½ of the moving speed of the irradiation unit 6. In addition, since the moving member which moves the irradiation unit 6 and the reflection unit 21 in the left-right direction is well-known and commonly used, any conventionally known configuration can be adopted, and thus detailed description is omitted.

The reflecting unit 21 according to the first embodiment includes a second mirror 22 as an example of a reflecting member. The second mirror 22 is constituted by a reflecting mirror. The second mirror 22 has an inclination angle with respect to the horizontal so as to reflect the light 12 from the first mirror 13 downward. A third mirror 23 as an example of a reflecting member is disposed below the second mirror 22. The third mirror 23 is constituted by a reflecting mirror. The third mirror 23 has an inclination angle with respect to the horizontal so as to reflect the light 12 from the second mirror 22 to the left.
An imaging lens 26 as an example of an imaging element is arranged on the left side of the third mirror 23. The imaging lens 26 is fixedly supported by the scanner unit U2. The imaging lens 26 is configured by a lens that condenses the light 12 from the third mirror toward an imaging member CCD as an example of a reading member.

The imaging member CCD according to the first embodiment includes a red (R) imaging element 31 as an example of a first reading unit, and a green (G) imaging element 32 as an example of a second reading unit, And an imaging element 33 for blue (B) as an example of a third reading unit. In each of the image pickup devices 31 to 33, a color filter (not shown) as an example of a wavelength selection member is arranged corresponding to the color to be read.
The elements 31 to 33 according to the first embodiment are arranged side by side with a predetermined interval L1. That is, the prism 11 and the imaging lens 26 of the first embodiment are set so as to converge the reflected light 12 from the document Gi at the reading position Pr corresponding to the interval L1 between the elements 31 to 33.

(Function of the image reading apparatus of the first embodiment)
In the copying machine U according to the first embodiment having the above-described configuration, when the document Gi is read using the auto feeder U3, the document transport roll U3b transports the document Gi. At this time, the irradiation unit 6 moves below the automatic reading surface 1. Accordingly, the reading position Pr is held on the upper surface of the automatic reading surface 1. Accordingly, the surface of the document Gi conveyed by the document conveyance roll U3b passes the reading position Pr. That is, the document Gi and the reading position Pr move relatively, and the surface of the document Gi is scanned, so-called scanning.

When the document Gi is manually set on the upper surface of the manual reading surface 2, the exposure optical system A moves from the right end toward the left end. Therefore, the reading position Pr moves from the right to the left on the manual reading surface 2. Accordingly, the document Gi and the reading position Pr move relatively, and the document Gi is scanned.
The surface of the document Gi at the reading position Pr is irradiated with light 7a from the illumination member 7. The reflected light 12 that diverges from the surface of the document Gi at the reading position Pr is collimated by the prism 11 and then condensed by the imaging lens 26 via the mirrors 13, 21, and 22. The light 12 collected by the imaging lens 26 is imaged for each color by the elements 31 to 33 of the imaging member CCD.

3A and 3B are explanatory diagrams of a conventional color image reading method. FIG. 3A is an overall view of an image reading apparatus, FIG. 3B is an enlarged view of a reading position, and FIG. 3C is an enlarged view of an imaging member.
In FIG. 3, in the conventional reading method such as the techniques described in Patent Documents 1 and 2, the imaging member 01 has R, G, and B imaging elements 01a, 01b, and 01c arranged with an interval of 02. Yes. Therefore, the reading positions 03a, 03b, 03c of the respective colors on the platen glass 03 are also set with an interval 04 corresponding to the interval 02 between the image sensors 01a to 01c. That is, in the conventional configuration, a so-called line gap 04 is provided. In recent low-cost image forming apparatuses, the interval 04 is relatively large, such as 24 lines. That is, in FIG. 3, the document 06 needs to be conveyed by 12 lines before the position on the document 06 that has passed the B color reading position 03a reaches the G color reading position 03b. It is necessary to convey 24 lines before reaching the color reading position 03c. In the conventional reading method, the shift for 12 lines or 24 lines is corrected, and images of each color of R, G, and B are superimposed to realize color reading.

However, unevenness in the transport speed of the original 06 is caused by the eccentricity or partial wear of the transport roll 07, slippage between the transport roll 07 and the original 06, uneven friction between the original 06 and the platen glass 03, and the like. May occur. If unevenness occurs in the conveyance speed of the document 06, for example, the reading position of the document 06 may be shifted between the B color and the R color. Even when reading with a manual reading surface, the moving speed of the exposure optical system may be uneven. In this case, there is a problem that color misregistration occurs even when images of R, G, and B colors are superimposed.
In order to cope with this problem, it is most direct to narrow the interval 02 between the image sensors 01a, 01b, and 01c. However, in this case, there is a problem that the imaging member 01 becomes expensive.
The technologies described in Patent Documents 1 and 2 are technologies that make the light from each of the reading positions 03a to 03c telecentric on the premise that the reading position 03a to 03c of each color has an interval 04. It is not a technique for narrowing 04.

  On the other hand, in the copying machine U according to the first embodiment, the reflected light 12 from the same reading position Pr can be input to each of the imaging elements 31 to 33 via the prism 11. Accordingly, the line gap 04 is eliminated in the scanner unit U2 of the first embodiment. Therefore, in the R, G, and B color images, the reading position shift is prevented, and the occurrence of the color shift is suppressed. At this time, as the imaging member CCD, one having a relatively large interval L1 between the imaging elements 31 to 33 can be used. Further, the imaging lens 26 can be used as it is. Therefore, it is possible to improve color misregistration while using a low-cost imaging member CCD as compared with the conventional technique.

  In the first embodiment, the prism 11 is arranged on the original document Gi side rather than the imaging member CCD side with respect to the imaging lens 26 on the optical path of the light 12. When the prism 11 is disposed on the imaging member CCD side with respect to the imaging lens 26, fine adjustment is required when the light 12 collected by the imaging lens 26 is adjusted by the prism 11. That is, there is a problem that an error is likely to occur, and there is a problem that an assembly cost increases to reduce the error. On the other hand, in the first embodiment, the prism 11 is disposed on the original document Gi side, that is, on the object side, and adjustment can be performed relatively easily.

FIG. 4 is an explanatory diagram of an image reading apparatus according to the second embodiment corresponding to FIG. 2 of the first embodiment, FIG. 4A is an overall view of the image reading apparatus, and FIG. 4B is an enlarged view of a reading position.
In the description of the second embodiment, components corresponding to those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is 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.
In FIG. 4, the scanner unit U <b> 2 of the second embodiment has a concave mirror 11 ′ as an example of an optical member instead of the prism 11 and the first mirror 13 in the first embodiment. The concave mirror 11 ′ according to the second exemplary embodiment includes a reflective surface 11 a ′ that converges the reflected light 12 that diverges from the reading position Pr of the document Gi into parallel light and reflects it toward the second mirror 22.

(Operation of Example 2)
Similarly to the first embodiment, the scanner unit U2 of the second embodiment having the above-described configuration can improve the color misregistration while suppressing an increase in cost by using a low-cost imaging member CCD. is there.

(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 (H08) of the present invention are exemplified below.
(H01) In each of the above embodiments, the copying machine U is illustrated as an example of the image forming apparatus, but the present invention is not limited to this. For example, the present invention can be applied to a printer as an example of an image forming apparatus, a FAX, or a multifunction machine having a plurality of these functions. Further, the present invention is not limited to a single color image forming apparatus, and can be applied to a multicolor image forming apparatus. Furthermore, the present invention is not limited to the transfer belt B that holds the sheet S on the surface, and can be applied to a configuration that uses an intermediate transfer belt.

(H02) In the above-described embodiment, it is desirable to provide the prism 11 and the concave mirror 11 ′ in the illumination unit 6, but the present invention is not limited to this. For example, the prism 11 or the like may be provided in the reflection unit 21 or may be disposed on the upstream side of the imaging lens 26 on the optical path.
(H03) In the above-described embodiment, the shape, size, and position of the prism 11 and the concave mirror 11 ′ can be arbitrarily changed according to the design and specifications. For example, the prism 11 can be embedded in the automatic reading surface 1, that is, the glass and the prism 11 can be integrally formed. In this case, when an image is read through the automatic reading surface 1, when the image is read through the manual reading surface 2 while reducing color misregistration using the embedded prism 11, as in the conventional technique. It is also possible to adopt a configuration for correcting the color misregistration. That is, using the auto-feeder U3 that conveys various types of paper tends to cause speed irregularities and color misregistration more easily than when the exposure optical system A is moved. Therefore, when the reading is performed through the automatic reading surface 1, the color misregistration can be effectively reduced by using the prism 11. Alternatively, in the case of a scanner that is not provided with a manual reading surface 2 or a scanner that a user reads by holding the reading unit by hand and sliding on the paper, a so-called handy scanner, the prism 11 is incorporated in the reading surface 1. Thus, the color shift can be effectively reduced.

FIG. 5 is an explanatory diagram of setting of the reading position in the modified example.
(H04) In the above-described embodiment, the reading position Pr is preferably set to a width corresponding to one line, but is not limited thereto. For example, as shown in FIG. 5, the position of the focal point of the prism 11 is set above the reading surfaces 1 and 2, and on the reading surfaces 1 and 2, the positions where the R, G, and B images are read are It is also possible to adopt a configuration in which the interval L1 ′ is increased by one line. Even in this configuration, the reading member CCD can use, for example, a 24-line configuration, and color misregistration is more likely to occur than in the first embodiment, but R, G, B in the document Gi compared to the prior art. The image reading position can be brought closer, and color misregistration can be reduced. Therefore, it is possible to reduce color misregistration while suppressing an increase in cost as compared with the prior art.

(H05) In the above-described embodiment, the prism 11 and the concave mirror 11 ′ are preferably configured to output in parallel light, but are not limited thereto. For example, the relationship between the imaging lens 26 and the mirrors 22 and 23, or in addition, when an optical element such as a lens or a mirror is disposed on the optical path, the light converges more than parallel or converges more than incident light. It is also possible to output light that diverges rather than parallel. That is, the performance of the prism 11 and the like can be set in relation to other lenses and the like even if the prism 11 and the concave mirror 11 ′ are not converged so as to correspond to the imaging elements 31 to 33. .
(H06) In the above-described embodiment, the copying machine U having the scanner unit U2 has been exemplified. However, the present invention is not limited to this, and the present invention can be applied to a single device as an example of an image reading device.

(H07) In the above embodiment, as an example of the moving member, an auto feeder U3 as an example of a moving member for automatic reading, and a drive system of an exposure optical system A (not shown) as an example of a moving member for manual reading. Although the scanner provided with two was illustrated, it is not limited to this. For example, the present invention can be applied to a scanner unit U2 that does not include the auto feeder U3 or a configuration in which the exposure optical system A does not move only by the auto feeder U3. In addition, the present invention is not limited to the configuration in which the illumination unit 6 and the reflection unit 21 move, and can be applied to a configuration in which the units 6, 21, the imaging lens 26, and the imaging member CCD move integrally.
(H08) In the above-described embodiment, the configuration including the three imaging elements 31 to 33 of R, G, and B is illustrated as an example of the reading unit, but is not limited thereto. For example, when the complementary color CMYB system is used instead of the primary color system RGB, the number of image sensors is increased depending on the design, specifications, etc., such as increasing the number of image sensors or using another color system. It is possible to increase or decrease.

11 ... Transparent member,
11, 11 '... optical member,
11a: Incident surface,
11a '... reflecting surface,
11b ... output surface,
12 ... reflected light,
26: Imaging element,
31 ... 1st reading part,
32 ... a second reading unit,
A ... Optical system,
CCD: Reading member,
Gi ... medium,
Pr: Reading position,
U: Image forming apparatus,
U1 ... Image recording device,
U2 ... Image reading device,
U3: moving member.

Claims (5)

A moving member that relatively moves a medium having an image formed on a surface thereof and a reading position that is opposed to the medium and receives reflected light from the image;
A reading member that reads the reflected light, and is spaced apart from the first reading unit that reads the first color in the image along the direction corresponding to the relative movement with respect to the first reading unit. A second reading unit arranged at a position and reading a second color different from the first color;
An optical element disposed on an optical path between the reading position and the position where the reading member is located, an imaging element for converging light toward the first reading unit and the second reading unit; An optical member disposed on an optical path between the imaging element and a reading position, wherein the reflected light is applied to the imaging element in accordance with an interval between the first reading unit and the second reading unit. The optical member to converge with respect to the optical system,
An image reading apparatus comprising: The optical member configured by a transparent member having an incident surface on which diverged reflected light from a reading position is incident and an output surface on which the incident light is refracted into parallel light and output;
The image reading apparatus according to claim 1, further comprising: The image reading apparatus according to claim 2, wherein a focus position of the transparent member is set to the reading position. The optical member having a reflecting surface that reflects the reflected reflected light from the reading position as parallel light;
The image reading apparatus according to claim 1, further comprising: An image reading device according to any one of claims 1 to 4,
An image recording apparatus for recording an image read by the image reading apparatus on a medium;
An image forming apparatus comprising:

Images