JP4869840B2 - Image reading apparatus and adjustment method - Google Patents

Description

  The present invention relates to an image reading apparatus that feeds an original to a positioned line image reading means and reads the original, and more particularly, to an angle adjustment method between a line image read by the reading means and the conveyance direction of the original.

  2. Description of the Related Art An image forming apparatus in which an image reading apparatus equipped with an automatic document feeder is arranged on the upper part of a machine body has been put into practical use. An image reading apparatus equipped with an automatic document feeder passes a document fed by the automatic document feeder through a positioned line image reading means (contact image sensor or the like), and images on the opposite surface of the document. Read through.

  Patent Document 1 shows an image reading apparatus equipped with an automatic document feeder. Here, the line image reading means is moved (sub-scanned) under the glass plate on which the document is placed, and the image on the lower surface of the document in contact with the glass plate is fixedly read. Then, with the same reading means positioned at one end of the glass plate, the automatic document feeder transports the document and passes it over the reading means, so that the lower surface of the moving document flows through the glass plate. Read. The automatic document feeder separates and conveys originals one by one from a bundle of originals placed on a paper feed tray, and passes them through a reading unit and then discharges them to a paper output tray.

  Also, a white reference plate having a length corresponding to the entire length of the reading unit is disposed on the bottom surface of the automatic document feeder near where the reading unit is positioned during the flow reading. By positioning the reading means under the white reference plate and reading the white reference plate, output adjustment of a light receiving element array (CCD or the like) that reads a line image and correction of reading gradation (shading correction) for each pixel are performed.

  Patent Document 2 discloses an image reading apparatus in which an automatic document feeder is attached to a rear side so as to be openable and closable using a pair of hinges. Here, an elongated glass plate that allows the document to pass during flow reading is disposed close to the glass plate on which the document to be fixedly read is placed. A document guide is provided at the boundary between the two glass plates to guide the scanned document to the upper side, and the height of the document passing through the glass plate is positioned on the bottom surface of the automatic document feeder at the scanned position. A platen roller that rotates is arranged.

Japanese Patent Laid-Open No. 2-121471 Japanese Patent Laid-Open No. 2005-184069

  The automatic document feeder needs to convey the document in a direction perpendicular to the line image read by the reading unit. When the document is conveyed obliquely with respect to the reading means, a line image that obliquely crosses the document surface is read, and the generated image is inclined obliquely assuming that the line image is perpendicular to the document conveyance direction. Because it will end up.

  Therefore, conventionally, when the automatic document feeder is attached to the main body of the image reading apparatus, the original on which the reference pattern is printed is scanned and a test print is performed, and the inclination angle of the image is measured on the printed image. Thus, the tilt adjustment amount of the automatic document feeder was estimated. Adjustment has been performed in which the automatic document feeder is tilted and reattached in the direction in which the tilt angle of the print image is offset. After the adjustment, a similar test print was performed again to confirm that the tilt angle of the printed image was offset.

  However, in the test print, even if there is no inclination in the image data obtained by scanning the document, the skew of the sheet at the time of image formation is reflected in the print image. Therefore, the measurement of the inclination angle of the automatic document feeder by test print is poor in reproducibility, and the accuracy of one test print is poor. However, it is efficient to average the measurement results by performing a large number of test prints. bad.

  In addition, test printing cannot be performed without an image forming apparatus. Therefore, when the automatic document feeder is attached to the image reading apparatus before the image forming apparatus is installed, the inclination of the automatic document feeder cannot be adjusted. .

  Therefore, a proposal has been made to measure the inclination angle at the image data stage by partially enlarging a scanned image of a document and displaying it on a monitor screen without printing on paper. However, even in the automatic document feeder, the skew variation of each document (each feed) drifts and the inclination of the read image data varies, so that the automatic document feeder is highly reproducible with only one document reading. The amount of tilt adjustment cannot be measured.

  Therefore, adjusting the inclination angle of the automatic document feeder by actually scanning and reading the document decreases the adjustment accuracy. When the original is actually read again after adjustment and readjusted, if the required accuracy is severe, there is a possibility that the adjustment does not converge by repeating the measurement-readjustment procedure many times. There is a possibility that the adjustment efficiency will be reduced due to useless repetition and the adjustment cost will be increased, or the variation of adjustment for each shipped product may be increased.

It is an object of the present invention to provide an image reading apparatus and an adjustment method capable of remarkably increasing the measurement accuracy of the tilt adjustment amount of the automatic document feeder and adjusting the mounting angle quickly and easily with high accuracy and low cost. It is aimed.

An image reading apparatus according to the present invention includes a document feeding unit that feeds a document in the transport direction by a platen roller, and a document image that is fed in the transport direction on the reading surface by the document feeding unit. A main body provided with a reading means for reading in a crossing direction that intersects with the main body, an attachment means for attaching the document feeder to the main body, and attached to the main body by the attachment means in a predetermined service mode. Control means for causing the reading means to read a line image corresponding to a predetermined portion having a length in the intersecting direction in a predetermined area including the platen roller of the document feeding unit. Means for reading the reader of the document feeder attached to the main body by the attachment means based on a line image corresponding to the predetermined portion of the document feeder read by the reader; Outputs information relating to the inclination state of the information related to the tilt state, an image information including the line image and the predetermined reference line image corresponding to the predetermined portion, the body portion length in the cross direction A predetermined member having a thickness, and the control means obtains the predetermined reference line image by reading the predetermined member by the reading means .

  In the image reading apparatus of the present invention, the opposing surface of the document feeding unit is fixedly read by the reading unit without performing a test print or a document reading, and the inclination direction and the inclination angle of the document feeding unit are reflected. Create information. In other words, an image on the facing surface itself is read instead of the measurement document conveyed on the facing surface of the document feeding unit. At least one of irregularities, shadows of parts, dedicated indicators, symbols, platen rollers, white reference plates, etc. existing on the surface of the document feeding means facing the reading means within the moving (fixed reading) range is fixedly read.

  Therefore, from the fixed reading result of the document feeding unit, the inclination adjustment amount of the document feeding unit with respect to the reading unit can be obtained by eliminating the variation in the tilt of the document with respect to the document feeding unit for each document (for each feeding). it can.

  Therefore, the error factor included in the inclination adjustment amount of the document feeding means by the test print is removed, and the actual condition of the inclination of the document feeding means with respect to the reading means can be accurately grasped at one time. The inclination of the document feeding unit relative to the reading unit can be offset by a single adjustment based on the measured tilt adjustment amount. The adjustment result can be reliably confirmed by one measurement after the adjustment.

  Accordingly, the measurement accuracy of the tilt adjustment amount of the document feeding unit is remarkably increased, and even if the required accuracy of the tilt of the document feeding unit with respect to the reading unit is strict, the adjustment can be converged immediately after the measurement-adjustment is completed once. Since it is possible to improve the work efficiency of adjustment by eliminating useless repetition, the adjustment of the mounting angle can be done quickly and easily with high accuracy and low cost, and variation in adjustment for each shipped product is reduced.

  Hereinafter, an image forming apparatus 100 according to an embodiment of the present invention will be described in detail with reference to the drawings. The image reading apparatus of the present invention is not limited to the limited configuration of the embodiments described below. As long as the fed original is scanned and read, another embodiment in which a part or all of the configuration of each embodiment is replaced with the alternative configuration can be implemented.

  In the present embodiment, the image reading apparatus 2 disposed on the upper body of the image forming apparatus 100 will be described. However, the image reading apparatus of the present invention may be implemented not only as an image forming apparatus but also as a single flat table scanner, image data reading apparatus, character recognition apparatus (OCR), sheet processing apparatus, sheet processing apparatus, or the like.

  In this embodiment, an image forming apparatus that forms a monochrome image by transferring a toner image formed on a photosensitive drum to a sheet will be described. However, the image forming apparatus of the present invention can also be implemented by a full-color image forming apparatus that primarily transfers each separated color toner image formed on one or more photosensitive drums onto an intermediate transfer belt and then secondarily transfers it to a recording material. It can be mounted not only on an electrophotographic image forming apparatus but also on various image forming apparatuses such as an ink jet system, a thermal transfer system, and various printing systems. The present invention can be implemented not only as a printer but also as an image forming apparatus for various uses such as various printing machines, copiers, FAX machines, and multifunction machines.

<Image forming apparatus>
FIG. 1 is an explanatory view showing the overall configuration of the image forming apparatus in section. As shown in FIG. 1, an image forming apparatus 100 that performs electrophotographic image formation using a photosensitive drum 81 has an image reading device 2 mounted on the upper part of the machine body. The image reading device 2 is equipped with an automatic document feeding device 3 that separates a set of bundled documents one by one and feeds them to the image reading device 2. The image data of the document read by the image reading device 2 is transmitted to the image forming unit 80 and used for image formation on the sheet P.

  The sheets P are taken out one by one from the cassette 91 in which the sheet bundle is stored, waited by the registration roller 92, and the heads coincide with the toner images formed on the photosensitive drum 81, so that the photosensitive drum 81 and the transfer device 85 are aligned. It is sent to the interval.

  A charger 82, an exposure device 83, a developing device 84, a transfer device 85, and a cleaning device 86 are disposed around the photosensitive drum 81. The charger 82 uniformly charges the surface of the rotating photosensitive drum 81. The exposure device 83 scans the uniformly charged surface with laser light to form an electrostatic latent image. The developing device 84 supplies toner to the electrostatic latent image and develops the toner image. The transfer device 85 transfers the toner image on the surface of the photosensitive drum 81 to the sheet P. The cleaning device 86 removes the toner remaining on the photosensitive drum 81 after the transfer, and prepares for the next image formation.

  The sheet P on which the toner image has been transferred is heated and pressured by a fixing device 87 so that the toner image is melted and fixed on the surface. The fixed sheet is discharged to the discharge tray 88 and stacked.

<Image reading device>
2 is a perspective view of the image reading apparatus, FIG. 3 is an explanatory view of the main body configuration of the image reading apparatus, FIG. 4 is an explanatory view of the configuration of the image sensor, and FIG.

  As shown in FIG. 2, the automatic document feeder 3 can be opened and closed to the back side by serving as a presser plate for the document placed on the contact glass 4 for fixed reading on the upper surface of the main body of the image reading device 2. It is attached. A flow reading glass 5 is disposed in the vicinity of the contact glass 4 and allows the original fed by the automatic document feeder 3 to pass through during the flow reading. An image reference plate 12 in the main scanning direction and an image reference plate 13 in the sub-scanning direction, which occupy two sides of the contact glass 4 and serve as a guide for setting a fixed-read original, are attached.

  As shown in FIG. 3, the image reading device 2 reads an image on the lower surface of the document using a contact image sensor 7 that reads a line image. A method of moving the contact image sensor 7 under the contact glass 4 and reading a document placed on the contact glass 4 is generally called “fixed reading”. On the other hand, generally speaking, the contact image sensor 7 is positioned and stopped under the flow reading glass 5, and a method of reading a document conveyed by the automatic document feeder (3: FIG. 2) and moving on the flow reading glass 5 is generally “flowing”. Say “Read”.

  In the image reading device 2, the contact glass 4 and the flow reading glass 5 are arranged in a plane with the support stay 6 interposed therebetween. The contact image sensor 7 is attached to a carriage (running body) 8 so as to be movable up and down, and a slight gap is secured between the contact image sensor 7 and the contact glass 4 (flow-reading glass 5) by guide rails (not shown) arranged in front and rear. It is positioned at the height position. The carriage 8 is fixed to the drive belt 10 and moves in the arrow direction as the drive belt 10 driven by the drive motor 9 circulates.

  A home position sensor 11 for detecting the home position of the carriage 8 is provided immediately below the support stay 6. By moving the carriage 8 from the position detected by the home position sensor 11 along the lower surface of the contact glass 4, the contact image sensor 7 reads the lower surface of the document in a fixed manner. At the time of flow reading, the carriage 8 is moved from the position detected by the home position sensor 11, and the contact image sensor 7 is positioned and stopped under the flow reading glass 5.

  As shown in FIG. 4, the contact image sensor 7 includes a rod-like light source 7a using LEDs, a lens 7b in which minute lens elements are integrated in a plate shape, and an image sensor such as a CCD in which light receiving elements are arranged in a line. 7c is fixed and assembled together. The contact image sensor 7 emits light from the light source 7a to illuminate the opposite surface, and the illuminated image is projected onto the image sensor 7c by the lens 7b. The image sensor 7c reads a line image from the projected image to generate an image signal, and the image signal is converted into a density gradation for each pixel by a conversion circuit (not shown). Image data formed from the density gradation of the line image is transmitted to a recording medium (not shown) or the control unit 90 of the image forming apparatus 100 shown in FIG.

  As shown in FIG. 5, the above-described image reference plate 12 in the main scanning direction is attached to the upper surface of the contact glass 4 adjacent to the support stay 6, and a white reference plate is provided on the back side of the image reference plate 12. 14 is pasted. The white reference plate 14 is an elongated member that faces the entire length of the contact image sensor 7. The white color of the white reference plate 14 is 255 out of 0 to 255 levels in terms of luminance value. In general, the luminance value 255 is a white value that is no higher.

  Regardless of fixed reading or flow reading, the contact image sensor 7 is positioned below the white reference plate 14 before reading the image of the document, and the white reference plate 14 illuminated by the light source (7a: FIG. 4) is used as the lens (7b: All white signals are collected by reading with the image sensor (7c: FIG. 4) via FIG.

  A shading correction circuit (not shown) mounted on an image processing board (not shown) of the image reading device 2 stores an all white signal read by the contact image sensor 7 as an absolute white reference, and the contact image sensor 7 A shading correction process is performed to cancel the non-uniformity of the image signal of the line image when the original is read. The shading correction circuit corrects the density distribution of the line image read from the original by using the density distribution of the line image read from the white reference plate 14.

  The non-uniformity of the line image read by the contact image sensor 7 is caused by the non-uniformity of the light amount of the light source 7a, the non-uniformity of transmission of the lens 7b, or the non-uniformity of sensitivity of the image sensor 7c shown in FIG. .

<Automatic document feeder>
6 is an explanatory diagram of a cross-sectional configuration of the automatic document feeder, FIG. 7 is an explanatory diagram of back side reading by the automatic document feeder, FIG. 8 is an explanatory diagram of a mounting structure of the automatic document feeder, and FIG. It is explanatory drawing of an attachment state. 9A is an enlarged view of the right hinge, and FIG. 9B is an attached state of the left and right hinges.

  As shown in FIG. 6, the automatic document feeder 3 separates the documents 18 one by one from the document bundle set on the document tray 17, feeds them to the image reading device 2, and passes over the flow-reading glass 5. Then, it is discharged to the document discharge tray 28.

  The documents 18 fed into the automatic document feeder 3 by the lowered pickup roller 19 are separated one by one by a separation portion in which the separation pad 21 is pressed against the separation roller 22 by a pressing spring 20. When only one document 18 is sent, the separation roller 22 sends the document 18 to the transport roller pair 23, but when the document 18 is sent in an overlapping manner, the lower document 18 that overlaps the uppermost document 18. Is prevented from entering by the separation pad 21, and only the uppermost document 18 is fed into the conveying roller pair 23.

  The document 18 is transferred from the conveyance roller pair 23 to the conveyance roller pair 24, passes over the flow reading glass 5, and flows an image on the lower surface by the contact image sensor (7: FIG. 4) positioned and stopped at the reading position 26. Read. In the case of single-sided reading, the document 18 that has passed over the flow-reading glass 5 is discharged from the discharge roller pair 27 to the document discharge tray 28 via the conveyance roller pair 25.

  As shown in FIG. 7, when reading both sides of the document 18, after the trailing edge of the document 18 passes the reverse flag 29, the paper discharge roller pair 27 reverses and the document 18 is transported back to the transport roller pair 23. To do. The document 18 whose front and back are reversed by the switchback conveyance is transferred to the conveyance roller pair 24, passes through the flow reading glass 5, and is read on the surface opposite to the first time. The document 18 that has passed over the flow reading glass 5 is discharged from the discharge roller pair 27 to the document discharge tray 28 via the conveying roller pair 25.

  On the upper surface of the flow reading glass 5 of the image reading device 2, a scraping sheet 5a for scraping off dust on the reading surface of the document 18 is attached. The scraping sheet 5a is affixed on the flow-reading glass 5 so that the longitudinal direction (main scanning direction) of the contact image sensor 7 coincides with the parallel direction. The support stay 6 that supports the opposite sides of the contact glass 4 and the flow reading glass 5 is formed with a slope that guides the document 18 that has passed through the flow reading glass 5 upward and guides it to the conveying roller pair 25.

  As shown in FIG. 8, the automatic document feeder 3 is installed on the upper surface of the apparatus body of the image reading apparatus 2 so as to be openable and closable backward using a left hinge 30a and a right hinge 30b.

  The left hinge 30a and the right hinge 30b can be opened and closed in the range of 0 to 90 degrees, and are biased in the opening direction by a built-in torsion coil spring. As a result, when the image reading apparatus 2 performs fixed reading, the original can be placed on the contact glass 4 by opening the automatic original feeding apparatus 3 rearward with a force lighter than the weight of the automatic original feeding apparatus 3. After the end of the fixed reading, the automatic document feeder 3 can be opened rearward with a force lighter than the weight of the automatic document feeder 3 to take out the document.

  The left hinge 30a and the right hinge 30b are fixed to the automatic document feeder 3 in advance. The left and right hooks 31a and 31b attached to the upper surface of the apparatus body of the image reading apparatus 2 are hooked with the left hinge 30a and the right hinge 30b to position the automatic document feeder 3, and the left and right fixing screws 32a, At 32b, the left hinge 30a and the right hinge 30b are fixed to the upper surface of the main body of the image reading apparatus 2, and thereafter the hook screws 31a and 31b are tightened.

  As shown in FIG. 9A, the opening 33b of the right hinge 30b is formed to have a size through which the hook screw 31b passes. Since the left hinge (30a: FIG. 8) is formed in the same manner, the automatic document feeder 3 can be attached by passing the left and right hook screws 31a (31b: FIG. 8) in a relaxed state.

  As shown in FIG. 9 (b), the openings 33a and 33b have a keyhole shape, and after passing through the circular screws and passing the screws 31a and 31b, the openings 33a and 33b are slid to a square portion to automatically feed the document. 3: Temporary positioning of FIG. In this state, the fixing screw 32a is loosely attached to the opening 34a of the left hinge 30a, and the automatic document feeder (3: FIG. 8) is used as the rotation center when adjusting the tilt. Since the opening 34b of the right hinge 30b is a long hole, the automatic document feeder (3: FIG. 8) is rotated within the range of the opening 34b to adjust the inclination. The edge of the opening 34b of the right hinge 30b is provided with a mark 35 as a mark for tilt adjustment. The mark 35 serves as a mark for a screw tightening position, and the fixed screw 32a serves as a center (fulcrum). 3: Adjust the inclination of FIG.

<Positioning of contact image sensor during scanning>
FIG. 10 is an explanatory diagram of flow reading position detection control.

  As shown in FIG. 4, the automatic document feeder 3 is provided with a platen roller 15 positioned above the flow-reading glass 5. The platen roller 15 is driven and rotated by the document 18 to reduce the conveyance load of the document 18 and to prevent the document 18 passing through the flow reading glass 5 from floating, thereby preventing the read image from blurring. In order to avoid the background color of the semi-transparent document, the platen roller 15 is white with a brightness value of no more than that (brightness of 255 or more). The platen roller 15 is installed in a direction perpendicular to the conveyance direction of the document 18 by the automatic document feeder 3 almost directly above the flow reading position 26 where the contact image sensor 7 is positioned and stopped during the flow reading.

  A white sheet 16 is provided on the automatic document feeder 3 so as to partially overlap the platen roller 15. The white sheet 16 serves as a positioning reference when the contact image sensor 7 is positioned at the flow reading position 26 prior to the flow reading. A gap 16a is formed between the white sheet 16 and the platen roller 15, and a shadow is created in the gap 16a by illumination of the light source 7a, thereby partially reducing the luminance of the facing surface of the contact image sensor 7.

  When the contact image sensor 7 is positioned at the flow reading position 26, the contact image sensor 7 is moved along the flow reading glass 5 to search the lowering position 16 b of the brightness, and the lower surface of the automatic document feeder 3 is moved. Read fixedly.

  That is, the contact image sensor 7 is moved from the home position below the support stay 6 to the left end position in FIG. (Luminance change) is continuously detected. FIG. 10 is a graph of the position-luminance relationship when moving in the right direction. However, FIG. 10 shows experimental results in which illumination is lowered to ensure contrast, and the contact image sensor 7 is allowed to flow and the reading position 26 is allowed to pass without stopping.

  Then, the contact image sensor 7 is positioned at the flow reading position 26 by moving the contact image sensor 7 by a predetermined movement distance after detecting the peak in luminance below the threshold LEVEL shown in FIG.

  In other words, the portion where the luminance is reduced in FIG. 10 is used as a reference, and the position moved by 3 mm, for example, toward the fixed reading side from the reference is set to the position of the contact image sensor 7 during the flow reading. In the positioning control of the contact image sensor 7, a home position sensor (11: FIG. 3) that is a position reference when the contact image sensor 7 is moved is used as a reference for the position of the contact image sensor 7.

  When the automatic document feeder 3 is attached to the image reading device 2, there are attachment errors and tolerances, and there are also attachment errors and tolerances at the position of the home position sensor (11: FIG. 3). Accordingly, when the contact image sensor 7 is moved from the position of the home position sensor (11: FIG. 3) to the left in FIG. 4 by a predetermined distance and stopped, an error of the flow reading position 26 occurs. The positioning sequence described with reference to FIG. 10 is effective because the flow reading position 26 is aligned with the actual product to remove the error caused by the mounting error and tolerance described above. Such a positioning sequence is collectively referred to as reading position detection, and the fixed reading of the lower surface of the automatic document feeder 3 by the image sensor 7 is referred to as back scanning.

<Adjustment Method of First Embodiment>
FIG. 11 is an explanatory diagram of a backscan image, and FIG. 12 is an explanatory diagram of a printout of the backscan image. In FIG. 11, (a) is a normal attachment state, (b) is an inclined attachment state.

  An operation unit (not shown) is arranged on the front side of the image forming apparatus 100 shown in FIG. The service mode is selected by operating the operation unit, and the switch setting of the service mode is set to the back scan mode (the mode in which the contact image sensor is flowed and positioned at the reading position). When the start button is pressed in this state, the contact image sensor 7 starts reading from the position of the white reference plate 14 affixed to the surface of the contact glass 4 as shown in FIG. The back scan image is read until it passes through the scraping sheet 5a pasted on the upper surface of the flow reading glass 5. The back scan image is stored in a storage device such as a general-purpose hard disk or a general-purpose memory mounted on the control unit 90 of the image forming apparatus 100. Thereafter, the above-described positioning sequence is executed, and the contact image sensor 7 is positioned and stopped at the flow reading position 26.

  As shown in FIG. 11A, the back scan image is an image obtained by fixedly reading the lower surface of the automatic document feeder 3 through the flow reading glass 5, and includes a support stay 6, a platen roller 15, a white sheet. 16, The scraping sheet 5a is included. Line A is a shadow of the step of the gap 16 a between the white sheet 16 and the platen roller 15. Line B is a shadow of the end portion of the scraping sheet 5 a attached on the flow-reading glass 5.

  As shown in FIG. 11B, when the automatic document feeder 3 is attached with an inclination, the line A is inclined. This is because, in the apparatus main body of the image reading apparatus 2, a scraping sheet 5 a is attached in accordance with the contact image sensor 7 as shown in FIG. 4. Accordingly, the distance between the line A and the line B of the back-scan image is measured at both ends, and the front side distance C1 and the back side distance C2 are measured. Line A and line B are aligned by reattaching the device (3: FIG. 8).

  Specifically, when the back scan image printout is instructed through the operation unit after the positioning sequence is completed, the image forming apparatus 100 shown in FIG. An image enlarged by taking out F: front side and R: back side is printed out as shown in FIG. The adjustment person actually measures the near side distance C1 and the back side distance C2 from the printout, and corrects the inclination angle of the automatic document feeder 3 as described with reference to FIGS.

<Adjustment Method of Second Embodiment>
The actually measured backscan image shown in FIG. 12 may be displayed on an external monitor screen connected to the image reading apparatus 2. In this case, it is not necessary to activate the image forming unit 80 shown in FIG. 1 to perform image formation. The assembly / adjustment of the automatic document feeder 3 with respect to the image reading device 2 can be completed at a stage before being mounted on the image forming unit 80.

<Adjustment Method of Third Embodiment>
When acquiring and displaying a back-scan image, it is not always necessary to rely on an existing switch operation from an operation unit provided in a copying machine, a multifunction machine, or the like. A back scan image may be acquired by a command input operation from an external computer connected to the image reading apparatus 2.

<Adjustment Method of Fourth Embodiment>
FIG. 13 is a flowchart of an adjustment procedure according to the fourth embodiment, FIG. 14 is an explanatory diagram of measurement results in a normal attachment state of the automatic document feeder, and FIG. 15 is a measurement result in an inclined attachment state of the automatic document feeder. It is explanatory drawing. In the fourth embodiment, the luminance change in two pixels in the line image is extracted, and the rotation direction and the rotation amount of the automatic document feeder 3 are calculated.

  As shown in FIG. 13, a work computer is connected to the image reading apparatus 2, the back scan mode is started, and various settings are made (S11). The contact image sensor 7 is moved for back scan, the back scan image is recorded, the pixel pitch in the moving direction, and the brightness measurement selected one by one from the front side and the back side of the contact image sensor 7 Each pixel is set.

  The working computer controls the image reading device 2 and the automatic document feeder 3 to perform normal document reading operations, and also performs various test mode operations to collect, record, and process image data. Performs data extraction, various statistics and output processing.

  Next, the back scan mode is started by operating the switch displayed on the work computer (S12). As described above, the contact image sensor 7 reads the white reference plate 14 (S13), and the luminance correction value of each pixel of the line image (main scanning direction) read by the contact image sensor 7 is calculated and stored ( S14).

  Next, after the carriage 8 is detected by the home position sensor 11 and moved to the back scan start position (S15), the back scan is started at a predetermined moving speed and at intervals corresponding to the pixel pitch in the moving direction. The contact image sensor 7 reads a line image (S16).

  Then, the brightness of two pixels (set in S11) in the line image subjected to the shading correction is stored in the data storage unit P1 (S17). S16 and S17 are repeated until the contact image sensor 7 reaches the set moving range (NO in S18).

  When the contact image sensor 7 reaches the set movement range (YES in S18), continuous data of luminance distribution as shown in FIG. 14 (or FIG. 15) is formed in two pixels. As shown in FIG. 11B, the two pixels are set at a distance in the longitudinal direction of the contact image sensor (7: FIG. 2). Therefore, if the white sheet 16 is parallel to the contact image sensor (7: FIG. 4), the luminance peaks (drops) of the pixels a and b match as shown in FIG. As shown in FIG. 15, the luminance peaks of the pixels a and b are off.

  The working computer calls the luminance data of the pixels a and b from the storage unit P1, extracts the peak position of the depression that interrupts the threshold LEVEL (S19), and the pixel b (back side) from the peak position of the pixel a (front side). ) Is subtracted (S20). If the result of the subtraction is 0 (match in S20), it is determined that adjustment is not necessary and an OK determination is displayed (S24).

  However, if the subtraction result is positive (C1> C2), the number of steps by which the automatic document feeder 3 is rotated clockwise (35: FIG. 9B) is displayed on the work computer. (S21).

  On the other hand, if the subtraction result is negative (C1 <C2), the number of steps by which the automatic document feeder 3 is rotated counterclockwise (35: FIG. 9B) is displayed on the work computer. (S23).

  The adjustment person adjusts the mounting angle of the automatic document feeder 3 according to the display on the work computer (S22), then performs the back scan mode again (S12), and confirms the adjustment result.

  Similar to the positioning of the contact image sensor at the time of flow reading, at regular intervals in the sub-scanning direction (reading direction) at two positions on the front side and the back side in the main scanning direction (sensor alignment direction of the contact image sensor 7). For example, for each 0.1 mm unit, a luminance value (black: 0 to white: total 256 gradations of 255) that is a black to white expression means is detected, and a luminance-position distribution graph at each position is displayed. FIG. 14 shows the result. The peak of the brightness drop of the pixels a and b on the graph is the position of the shadow read by the contact image sensor 7, and the shadow of the step of the gap 16a between the white sheet 16 and the platen roller 15 shown in FIG. The brightness drop at is larger than the brightness drop at the shadow of the scraping sheet 5a attached to the flow-reading glass 5, so that both can be separated by the threshold LEVEL.

  When the automatic document feeder 3 is attached obliquely to the main body of the image reading device 2, the back scan image is as shown in FIG. 11B, and as shown in FIG. The luminance drop peak of b shifts.

  Using this phenomenon, when the moving distance to the brightness drop position of the pixel a on the near side coincides with the movement distance to the brightness drop position of the pixel b on the back side, the automatic document feeder 3 and the document reading It can be determined that the right angle of the apparatus 2 with the apparatus main body is correctly attached.

  A determination function for determining whether or not the luminance drop position is the same between the near pixel a and the far pixel b can be held in the control unit 90 of the image forming apparatus 100 as a maintenance program. In this case, the determination function may be activated each time the automatic document feeding device 3 is used to perform the scanning, and the determination result may be recorded together with the date and time. When a trouble with the tilt of the print image occurs, a determination result can be called to quickly determine whether or not the tilt of the automatic document feeder 3 is the cause.

  When the adjustment of the attachment of the automatic document feeder 3 is readjusted by putting the plus and minus values of the luminance drop positions at the pixels a and b into the determination routine, the automatic document feeder 3 is centered on the attachment fulcrum. It is possible to issue a rotation direction instruction message for determining and displaying whether to rotate right or left.

  In the fourth embodiment, the shift amount of the brightness drop position is obtained for the two pixels a and b of the contact image sensor 7, but another pixel c and d separated by a distance equal to the distance between the pixels a and b. Similarly, the deviation amount of the luminance drop position may be obtained and the deviation amount of the average value may be output. Even if the luminance drop position is detected for three or more pixels, the relative inclination angle of the contact image sensor 7 and the shift amount at both ends of the contact image sensor 7 are calculated and output by proportional processing according to the pixel arrangement relationship. Good.

<Adjustment Method of Fifth Embodiment>
FIG. 16 is a flowchart of the adjustment procedure of the fifth embodiment. The flowchart of FIG. 16 shows only the changed part from the flowchart of FIG. 13, and the illustration and detailed description of the parts common to the fourth embodiment are omitted.

  In the fourth embodiment, the case where the brightness drop position is completely coincident (positioned within the reading pitch in the movement direction) between the pixel a on the near side and the pixel b on the back side is determined to be OK, but in the fifth embodiment, it is determined OK. A range is given to the judgment.

  That is, in the subtraction determination (S20) in the flowchart of FIG. 13, if the subtraction result is within a predetermined range centered on 0, an OK determination is made, and an adjustment recommendation is determined only when the predetermined range is exceeded.

  As shown in FIG. 16, the work computer extracts the peak position of the luminance drop in the near pixel a and the far pixel b (S19), and subtracts the peak position of the pixel b from the peak position of the pixel a. (S30). If the result of the subtraction is within the range of ± 2 pixel pitch (match in S30), it is determined that adjustment is not necessary, and an OK determination is displayed (S24).

  However, if the subtraction result is larger than the two-pixel pitch, the number of steps by which the automatic document feeder 3 is rotated clockwise (35: FIG. 9B) is displayed on the work computer. (S31).

  On the other hand, if the subtraction result is smaller than the two-pixel pitch, the number of steps by which the automatic document feeder 3 is rotated counterclockwise (35: FIG. 9B) is displayed on the work computer. (S33).

  The adjustment person adjusts the mounting angle of the automatic document feeder 3 according to the display on the work computer (S22), and then performs the back scan mode again to check the adjustment result.

  According to the fifth embodiment, even when a slight shift occurs in the brightness drop position between the pixel a on the near side and the pixel b on the back side, by setting the allowable range of shift in advance, for example, By setting the allowable range to be ± 2.0 mm, it is possible to widen the allowable adjustment range by giving a width to the right angle when the automatic document feeder 3 is installed.

<Adjustment method of comparative example>
FIG. 17 is a plan view of a reference document used in the adjustment method of the comparative example, and FIG. 18 is a plan view of a test print. In the adjustment method of the comparative example, the image forming apparatus 100 described with reference to FIGS. 1 to 10 performs a test print to adjust the inclination of the automatic document feeder 3.

  When the automatic document feeder 3 is attached to the image reading device 2, the reference document 34 with vertical and horizontal lines shown in FIG. 17 is set in the automatic document feeder 3 and the image forming apparatus 100 is set in the copy mode. Press the start button. Accordingly, the reference document 34 is scanned and read using the automatic document reader 3, and the test print 35 shown in FIG. 18 is printed out using the image forming unit 80.

  The person in charge of adjustment compares the reference original 34 and the test print 35 to confirm whether the image is oblique. When an image of the test print 35 is formed obliquely, the automatic document feeder 3 is rotated in the direction opposite to the direction in which the image is bent, and the test print is executed again. This procedure is repeated to adjust the tilt. This adjustment is called skew adjustment. The skew adjustment is performed when the automatic document feeder 3 is installed in a factory, or when a product service person or user installs the automatic document feeder 3 on the market as an optional equipment. .

However, the cause of the oblique image of the test print 35 is not necessarily the inclination of the automatic document feeder 3. The following causes are also possible.
(1) Skew and meander of document conveyance in automatic document feeder (2) Inclination due to mounting component tolerance of automatic document feeder (3) Inclination due to contact component size tolerance (4) Image formation Skew and meander of printed paper

  Accordingly, when the skew feeding adjustment is performed by relying on the test print 35, in the worst case, when the skew of the sheet P appears suddenly in the image forming unit 80, the tilt adjustment of the automatic document feeder 3 can be mistaken. There is sex. It is troublesome to repeat the test print 35 many times and to rotate and fix the automatic document feeder 3 each time.

  Whether or not the conveyance direction of the document 18 conveyed in the direction perpendicular to the platen roller 15 of the automatic document feeder 3 and the main scanning direction which is the sensor array of the contact image sensor 7 are perpendicular to each other directly. There was no current means of confirmation.

  On the other hand, according to the adjustment methods of the first to fifth embodiments described above, it is not necessary to flow a document when the automatic document feeder 3 is attached to the main body of the image reading device 2, and as a result, at the factory Assembling adjustments, or on-site replacement adjustment times by users and service personnel are shortened. In addition, it is possible to always install the automatic document reading device 3 uniformly, and to reduce the installation variation due to the difference between the image reading devices.

<Correspondence with Invention>
The image reading apparatus 2 includes a contact image sensor 7 that reads a line image on the opposite surface while being positioned at the flow reading position 26, and an automatic document feeder that moves the document in a direction crossing the line image along the opposite surface. The feeding device 3 includes a driving motor 9 and a driving belt 10 that move the contact image sensor 7 in a direction crossing the line image along the facing surface. In the first embodiment, the automatic document feeder 3 operates the drive motor 9 in a state in which no document is fed, and the contact image sensor 7 causes the automatic document feeder 3 to be fixedly read, and the automatic document. And a control unit 90 that creates information (image data) relating to the inclination of the automatic document feeder 3 using a fixed reading result of the feeder 3.

  The image reading device 2 reads the lower surface of the automatic document feeder 3 by the contact image sensor 7 without performing a test print or a document reading, and the inclination direction and the inclination angle of the automatic document feeder 3 are adjusted. Create the reflected information. As the contact image sensor 7 moves, the unevenness of the lower surface of the automatic document feeder 3 facing, the shading of parts, the dedicated index, the pattern, the platen roller, the white reference plate, etc. are fixedly read.

  And just output the image in a form that can evaluate the inclination of the straight line in the line image direction that has been fixedly read, the temporal and spatial deviation of the two positions separated by a distance in the line image direction, the inclination of the image, etc. Good. Image processing is performed on the fixedly read image data, and the straight line and the two positions are extracted to automatically calculate and output the inclination adjustment amount of the automatic document feeder 3 with respect to the contact image sensor 7. Also good.

  In any case, variations in the inclination of the document relative to the automatic document feeder 3 for each document (each feeding) can be eliminated from the fixed reading result of the automatic document feeder 3. The error factor included in the tilt adjustment amount of the automatic document feeder 3 by the test print is removed, and the actual state of the tilt of the automatic document feeder 3 with respect to the contact image sensor 7 can be accurately grasped once. The tilt of the automatic document feeder 3 with respect to the contact image sensor 7 can be offset by a single adjustment based on the measured tilt adjustment amount. The adjustment result can be reliably confirmed by one measurement after the adjustment.

  Accordingly, the measurement accuracy of the tilt adjustment amount of the automatic document feeder 3 is remarkably increased, and even if the required accuracy of the tilt of the automatic document feeder 3 with respect to the contact image sensor 7 is strict, the measurement-adjustment is completed once. Can be converged immediately. Since it is possible to eliminate unnecessary repetition and increase the work efficiency of adjustment, the adjustment of the mounting angle can be performed quickly and easily with high accuracy and low cost, and the variation in adjustment among shipment products is reduced.

  In addition, by evaluating the result of reading a straight line parallel to the moving direction of the contact image sensor 7, it is also possible to take out information related to the right angle relationship (the inclination of the rail of the carriage 8) between the moving direction and the line image. However, since the movement stroke is short in the back scan, the accuracy is higher when the fixed read image on the contact glass 4 side is used.

  The inclination of the document conveyance direction with respect to the automatic document feeder 3 is determined mechanically by the automatic document feeder 3 after the document is actually read and read after the inclination adjustment of the automatic document feeder 3 is completed. It is desirable to adjust to.

  Further, when the contact image sensor 7 is tilted with respect to the apparatus main body of the image reading apparatus 2, when the automatic document feeder 3 is tilted to cancel the tilt adjustment amount, the automatic original with respect to the apparatus main body of the image reading apparatus 2. This results in an unsightly result that the feeding device 3 is inclined. Therefore, it is desirable to remove the inclination of the contact image sensor 7 with respect to the main body of the image reading device 2 prior to the fixed reading of the automatic document feeder 3.

  In the first embodiment, the contact image sensor 7 fixedly reads a line A that intersects the moving direction of the document at a right angle from the automatic document feeder 3, and the control unit 90 includes the automatic document feeder 3 that includes the line A. The fixed reading image of is output.

  In the modification of the first embodiment, the contact image sensor 7 reads from the automatic document feeder 3 a fixed line A that crosses the moving direction of the document at a right angle. The control unit 90 may extract the lines A and B by performing image processing on the fixed reading image of the automatic document feeder 3 including the line A, and obtain the inclination direction and the inclination amount of the lines A and B. Thereby, the inclination adjustment similar to 4th Embodiment can be performed.

  In the fourth embodiment, the contact image sensor 7 reads from the automatic document feeder 3 a fixed line A that crosses the moving direction of the document at a right angle. The work computer connected to the image reading apparatus 2 processes the fixed reading signal of the automatic document feeder 3 including the line A to obtain the inclination direction and the inclination amount of the line A.

  In the fourth embodiment, the work computer detects the output signal drop peak at the pixels a and b of the contact image sensor 7 spaced apart in the direction of the line image, and detects the output signal drop peak at the pixels a and b. Find the amount of deviation.

  In the fifth embodiment, the work computer corrects the moving direction of the document by the automatic document feeder 3 when the shift amount of the output signal drop peak in the pixels a and b deviates from a predetermined allowable range. Output direction and correction angle.

  The image reading apparatus 2 includes a white sheet 16 that is disposed on a surface facing the contact image sensor 7 of the automatic document feeder 3 and serves as an index when the contact image sensor 7 is positioned at the flow reading position 26. Line A is a shadow of the edge of the white sheet 16. Therefore, it is possible to add the positioning function of the automatic document feeder only by partially changing the existing positioning program using the existing positioning member.

  The image forming apparatus 100 includes an image reading device 2, an image forming unit 80 that forms an image read by the image reading device 2 on a sheet, an image reading by the image reading device 2, and an image forming by the image forming unit 80. An operation unit (not shown) that can input a command to the control unit 90. A fixed reading of the automatic document feeder 3 is commanded through an operation unit (not shown).

  The image forming apparatus 100 includes an image reading device 2, an image forming unit 80 that forms an image read by the image reading device 2 on a sheet, an image reading by the image reading device 2, and an image forming by the image forming unit 80. An operation unit (not shown) that can input a command to the control unit 90. Image formation by the image forming unit 80 using the fixed reading image is instructed through an operation unit (not shown).

  The first to fifth embodiments are methods for manufacturing an image reading apparatus 2 in which an automatic document feeder 3 is attached to an apparatus main body including a contact image sensor 7 that reads line images. A first step in which the lower surface of the automatic document feeder 3 attached to the apparatus main body is fixedly read by the contact image sensor 7, and a second step of adjusting the inclination angle of the automatic document feeder 3 using the result of the fixed reading of the lower surface. A process.

1 is an explanatory diagram showing the overall configuration of an image forming apparatus in cross section. 1 is a perspective view of an image reading device. It is explanatory drawing of the main body structure of an image reading apparatus. It is explanatory drawing of a structure of an image sensor. It is an enlarged view of a main body upper section of an image reading device. 2 is an explanatory diagram of a cross-sectional configuration of an automatic document feeder. FIG. FIG. 6 is an explanatory diagram of back side reading by an automatic document feeder. It is explanatory drawing of the attachment structure of an automatic document feeder. It is explanatory drawing of the attachment state of a hinge. It is explanatory drawing of flow reading position detection control. It is explanatory drawing of a back scan image. It is explanatory drawing of the printout of a back scan image. It is a flowchart of the adjustment procedure of 4th Embodiment. It is explanatory drawing of the measurement result in the normal attachment state of an automatic document feeder. It is explanatory drawing of the measurement result in the attachment state in which the automatic document feeder was inclined. It is a flowchart of the adjustment procedure of 5th Embodiment. It is a top view of the reference | standard original used with the adjustment method of a comparative example. It is a top view of a test print.

Explanation of symbols

2 Image reading device 3 Document feeding means (automatic document feeding device)
4 Contact glass 5 Flow-reading glass 5a Scraping sheet 6 Support stay 7 Reading means (contact image sensor)
8, 9, 10 Moving means (carriage, drive motor, drive belt)
15 Platen roller 16 White sheet 18 Document 26 Reading position (flow reading position)
30a Left hinge 30b Right hinge 31a, 31b Hook screw 32a, 32b Fixed screw 80 Image forming means (image forming unit)
90 Control means, information creation means (control unit)
100 Image forming apparatus A, B Straight line
a, b pixels (2 points)

Claims (6)

A document feeding section that feeds a document in the conveying direction by a platen roller;
A main body provided with reading means for reading a document image fed in the conveying direction on the reading surface by the document feeding unit in an intersecting direction intersecting the conveying direction;
An attachment means for attaching the document feeder to the main body;
In a predetermined service mode, a line image corresponding to a predetermined portion having a length in the intersecting direction in a predetermined area including the platen roller of the document feeding unit attached to the main body by the mounting unit. Control means for reading by the reading means,
The control unit is configured to read the reading unit of the document feeding unit attached to the main body by the mounting unit based on a line image corresponding to the predetermined portion of the document feeding unit read by the reading unit. Output information related to the tilt state with respect to
The information related to the tilt state is image information including a line image corresponding to the predetermined portion and a predetermined reference line image,
The image reading apparatus according to claim 1, wherein the main body includes a predetermined member having a length in the intersecting direction, and the control unit obtains the predetermined reference line image by reading the predetermined member by the reading unit. The image reading apparatus according to claim 1, wherein the document feeding unit includes a reference member provided with a gap with respect to the platen roller, and the predetermined portion is a portion corresponding to the gap. . The control unit reads the reference member by the reading unit, and sets a reading position of the reading unit when reading a document image fed by the document feeding unit based on a reading result. The image reading apparatus according to claim 2 . A document feeding unit that feeds a document in the conveyance direction by a platen roller, and a reading that reads a document image fed in the conveyance direction on the reading surface by the document feeding unit in a crossing direction that intersects the conveyance direction. In an adjustment method for adjusting an inclination state of the image reading apparatus with respect to the main body unit, comprising: a main body unit including a unit; and an attachment unit for mounting the document feeding unit to the main body unit.
In a predetermined service mode, a predetermined length in the intersecting direction in a predetermined region including the platen roller of the document feeding unit attached to the main body by the mounting unit using the reading unit. A first step of reading a line image corresponding to the part;
After the first step, based on a line image corresponding to the predetermined portion of the document feeding unit read by the reading unit, the document feeding unit attached to the main body by the mounting unit. possess a second step of outputting a Sekiru information on the inclination state with respect to the reading means, and
In the first step, a line image corresponding to the predetermined portion of the document feeding unit and a predetermined reference line image of the main body unit are continuously read,
In the second step, as the information related to the tilt state, image information including a line image corresponding to the predetermined portion and a predetermined reference line image is output,
The main body includes a predetermined member having a length in the intersecting direction, and the reading unit obtains the predetermined reference line image by reading the predetermined member by the reading unit . The adjustment method according to claim 4 , wherein the document feeding unit includes a reference member provided via a gap with respect to the platen roller, and the predetermined portion is a portion corresponding to the gap. 6. The adjustment method according to claim 5 , wherein, as the reference member, a member for setting a reading position of the reading unit is also used when reading a document image fed by the document feeding unit. .

Images