JP4528319B2 - Document reader - Google Patents

Description

  The present invention includes a document feeding unit that feeds a document toward a document reading position on a document glass, and a document discharge unit that discharges the document on a side facing the document feeding unit across the document reading position. And a document reading unit configured to include a document reading unit that reads image information of a document passing through the document reading position.

  When foreign matter such as dust adheres to the surface of the original glass of the original reading unit, there is a problem that streak noise due to the foreign matter occurs every time the original is read, and image information faithful to the original cannot be obtained. When a noise occurs, the original glass surface has to be cleaned each time, and a complicated operation has to be performed.

As an example for solving such a problem, in a document reading apparatus that has a document transport mechanism and an imaging member and reads an image of a document with an imaging member at a document reading position while transporting the document with the document transport mechanism, When a document conveyed from a group of document bundles is read, the read data is detected, the read data is determined by the abnormality determination unit, and if an abnormal value is detected, the document reading position is detected by the reading position changing unit. There has been proposed an apparatus for reading an original while being shifted in a sub-scanning direction without a mark.
JP 2000-310820 A

  However, in the above-described example, image information faithful to the original can be obtained by changing from the original image reading position where the abnormal value is detected to another clean original image reading position. If the foreign matter adheres to any of the original image reading positions shifted in the sub-scanning direction, it will be moved to another clean original image reading position. There is also a problem that image information faithful to the original cannot be obtained because it cannot be changed.

  In view of the above-mentioned conventional drawbacks, the present invention can automatically remove foreign matter without foreign matter removal such as wiping off the original glass by a serviceman or administrator even if foreign matter adheres to the original glass. The point is to provide a sheet-through type document reading apparatus.

In order to achieve the above object, a first characteristic configuration of a document reading apparatus according to the present invention is to supply a document toward a document reading position on a document glass as described in claim 1 of the document of the claims. A document feeding section comprising: a document feeding section; a document feeding section that ejects the document on a side facing the document feeding section across the document reading position; and a document that passes through the document reading position And a document reading unit configured to include a document reading unit that reads image information of the document, and when the foreign material is detected on the document glass by the document reading unit, The conveyance mode is switched from the normal conveyance mode in which the original is conveyed with the original being separated from the original glass to the foreign matter removing conveyance mode in which the original is in contact with the original glass. In the foreign matter removing and conveying mode, the document conveying unit stops the document discharging operation in the document discharging unit or the document discharging speed is lower than the document feeding speed by the document feeding unit. The original is bent until it comes into contact with the original glass, and then the original discharge speed is controlled to be equal to the original feeding speed, and adheres to the original conveyed by the original conveying section. A cleaning mechanism for removing foreign matter is provided in the document discharge section .

According to the above-described configuration, when a foreign object is detected, the document is transported in the foreign material removal transport mode, so that the foreign material on the document glass can be removed by the transported document without manual intervention. In the foreign substance removal conveyance mode, the document discharge operation at the document discharge section is stopped or the document discharge speed is lowered from the document feed speed by the document feed section and bent until the document comes into contact with the document glass, Thereafter, by controlling the original discharge speed to be equal to the original feed speed, the original is conveyed in contact with the original glass, so that the original glass is brought into contact with the original glass as the original is conveyed. Foreign matter adhering to the original glass is removed. Foreign matter removed from the original glass and attached to the original is removed by a cleaning mechanism provided in the original discharge portion. At this time, since the document discharge speed is controlled to be equal to the document feed speed, the fluctuation of the transport speed in the sub-scanning direction is negligible, and the read image data is not greatly affected.

  According to the second characteristic configuration described in the second aspect, in addition to the first characteristic configuration described above, the conveyance mode switching unit is configured to read the document when the document is conveyed in the foreign matter removal conveyance mode. When the foreign matter on the original glass is no longer detected by the portion, the original conveying portion is switched from the foreign matter removing and conveying mode to the normal conveying mode.

  According to the above-described configuration, when the foreign matter is removed in the foreign matter removal and conveyance mode, the document is switched to the normal conveyance mode and the document is conveyed without coming into contact with the document glass, so that foreign matters such as paper dust adhering to the document are removed. The possibility of newly adhering to the original glass is avoided.

According to the third feature configuration, as described in claim 3, in addition to the first or second feature configuration described above , an entrance angle of the document to the document reading position can be switched to the document feeding unit. A guide plate is provided, and in the foreign matter removing and transporting mode, the document transporting unit abuts the document glass on the front side of the document reading position before the document reading position, and transports the document in that state. Thus, the guide angle of the guide plate is switched .

According to the above-described configuration, the leading edge of the document comes into contact with the document glass on the near side of the document reading position, so that the leading edge of the document is conveyed while being in contact with the document reading position of the document glass. Therefore, the foreign matter can be effectively removed by the leading edge of the document.

  As described above, according to the present invention, even if a foreign object adheres to the original glass, the foreign object can be automatically removed without necessarily performing a foreign object removal operation such as wiping the original glass by a serviceman or an administrator. A sheet-through type document reading apparatus can be provided.

  Hereinafter, an embodiment in which a sheet-through type document reading apparatus according to the present invention is mounted on a digital copying machine will be described. That is, the copying machine is composed of an original reading apparatus and an electrophotographic image forming apparatus, though not described in detail. As shown in FIG. 1, the document reading apparatus includes an imaging unit 5 having a CCD image sensor that reads image information of a document 1 conveyed in the sub-scanning direction at a document reading position 3 set at a position directly above the document glass 6. A document reading unit B including an optical system 4 for focusing the image of the document 1 at the document reading position 3 on the imaging unit 5; and document feeding for transporting the document 1 to the document reading position 3 The document feeding unit A includes a part A1 and a document discharge part A2 that discharges the read document.

  The document feeder A1 is fed with a document table 201 for placing a group of documents 1 and a pair of feed rollers 202 for feeding the documents 1 placed on the document table 201 one by one. A pair of registration rollers 203 that prepares the leading edge of the original 1 and supplies the original 1 toward the original reading position 3, and a guide plate 8 a that determines an entry angle of the original 1 supplied by the registration roller pair 203 to the original reading position 3. The document discharge section A2 includes a guide plate 8b that guides the read document 1 to the pair of discharge rollers 204, a cleaning brush 502 that removes foreign matters adhering to the conveyed document 1, and a cleaning. A dust box 501 for temporarily storing foreign matter removed by the brush 502 and the discharge roller pair 204 for discharging the document 1 are arranged along the conveyance path of the document 1. Are you.

  The optical system 4 includes a lamp 401 as a light source for illuminating the document 1 fed to the document reading position 3, a first mirror 402 that captures reflected light from the document 1, a second mirror 403, and a third mirror. When a document 1 is placed on a document glass 7 for placing a document in a mirror scanning optical system that includes a mirror 404 and a lens 405 that focuses the light beam from the third mirror 404 on the imaging unit 5. A mirror scanning mode in which the lamp 401 and the mirrors 402, 403, 404 scan (sub-scan) from the position indicated by the solid line in the figure to the position indicated by the alternate long and short dash line to read the image information of the document 1, and When the document 1 is transported by the document transport unit A, the lamp 401 and the mirrors 402, 403, 404 are fixed at the positions indicated by the solid lines in the drawing, and transported by the registration roller pair 203 (sub- It is then switchably configured with a sheet-through mode for reading the image information of the original 1 to be 査).

  A white shading correction plate 9 is provided above the document reading position 3, and white data of the shading correction plate 9 is read by the document reading unit B, and the light amount variation in the main scanning direction of the lamp 401 is based on the value. Further, correction data for variation in sensitivity in the main scanning direction of the CCD is calculated and derived.

  As shown in FIG. 2, the control unit 10 of the original reading apparatus includes an original reading control means 20 for controlling the original conveying part A and the original reading part B, and various rollers 202 for supplying the original as described above. 203, 204 and a drive signal output unit 14 for outputting a control signal for a motor or the like for driving the optical system 4, and signals from a plurality of document detection sensors arranged along the transport path and detecting the position of the document 1 are input. A sensor signal input unit 15 that performs the control, a reading control signal output unit 16 that outputs a control signal for the imaging unit 5, and an image processing unit 17 that performs predetermined image processing on the image data obtained from the imaging unit 5. The document reading control unit 20 includes a document conveyance control unit 30 and a document reading control unit 40, and is connected to an image formation control unit 19 that controls the operation of an electrophotographic image forming apparatus.

  In the sheet-through mode, when a foreign object adheres to the original glass 6, original data corresponding to that part is lost, and black streaks appear as noise in the sub-scanning direction. Therefore, the document reading control unit 40 includes a foreign matter detection unit 18 that detects the presence of foreign matter on the document glass 6 based on the shading correction plate 9 obtained from the imaging unit 5 or the read data of the document 1, and When a foreign object is detected, the transport mode of the document 1 transported by the document transport unit A is switched from the normal transport mode to the foreign material removal transport mode, and it is detected that the foreign material detection unit 18 has removed the foreign material in the foreign material removal transport mode. A transport mode switching means 21 is provided for switching to the normal transport mode when it is done.

  When the pixel value in the main scanning direction in which the shading correction plate 9 has been read before reading the document 1 deviates significantly from the standard value indicating “white”, the foreign matter detection unit 18 reads the document glass at the position corresponding to the pixel. 6 determines that there is a foreign object. The foreign matter detection unit 18 detects foreign matter on the original glass 6 when it detects “black” continuously for a predetermined number of pixels in the sub-scanning direction based on the pixel values read by the original reading unit B. Judge that it exists.

  A case where the original is conveyed in the normal conveyance mode by the conveyance mode switching means 21 will be described with reference to FIGS. When the document reading operation is started in the normal conveyance mode, the sheet feeding roller pair 202 is driven, and one sheet of the document group placed on the document table 201 is separated and fed, and the document is scanned after time T1. 1 is driven for a predetermined time T2 after it is detected by the registration sensor 203a, and stops when the loop is formed at the front end of the document 1 by contacting the stopped registration roller pair 203. As a result, the leading edge posture of the document 1 is corrected and oblique feeding is restricted.

  After a predetermined time T3 has passed in order to synchronize with the document reading timing by the imaging unit 5, the registration roller pair 203 and the paper discharge roller pair 204 are driven, and the document 1 is fed toward the document reading position 3. At this time, as shown in FIG. 8, the leading end of the document 1 contacts the document glass 6 on the downstream side of the document reading position 3, so that the document 1 is conveyed without contacting the document glass 6. .

  Further, when the leading end portion of the document 1 is guided by the guide plates 8c and 8b and reaches the sheet discharge roller pair 204, the document 1 is conveyed by both the registration roller pair 203 and the sheet discharge roller pair 204 (T5). . The conveyance speed of the original by the registration roller pair 203 is driven at a constant speed set in advance to maintain a predetermined resolution, and the conveyance speed by the discharge roller pair 204 is initially the conveyance speed by the registration roller pair 203. Is set faster than. Accordingly, the document 1 conveyed by the pair of rollers 203 and 204 is conveyed in a state of being separated upward from the document glass 6. At this time, since a slipping mechanism is provided on the driving roller side of the paper discharge roller pair 204, the document 1 is conveyed at a conveyance speed by the registration roller pair 203.

  When the timing at which the trailing edge of the document 1 passes through the registration roller pair 203 is detected by the registration sensor 203 a, the registration roller pair 203 is stopped at that timing, and the document 1 is moved outside by the discharge roller pair 204. Transported and discharged. At time T6 when the trailing edge of the document 1 passes through the registration roller pair 203 and is transported by the paper discharge roller pair 204, the document transport speed of the paper discharge roller pair 204 is set in advance to maintain a predetermined resolution. The speed is controlled so as to be driven at the constant speed, and thus the document 1 is conveyed at a constant conveyance speed during this time. When the discharge of the original 1 is confirmed by a discharge sensor 204a provided on the downstream side of the discharge roller pair 204, the discharge roller pair 204 is stopped.

  When the registration sensor 203a detects the trailing edge of the document 1, the second document is fed by the paper feed roller 202 after a predetermined time, and the same operation is repeated until the final document. As described above, in the normal transport mode, the document 1 is transported in a state of being separated from the document glass 6 without coming into contact with the document reading position 3, so that dust or dust such as paper dust is temporarily attached to the document 1. Even if it is, the document glass 6 is configured to be prevented from dropping and adhering to the vicinity of the document reading position 3.

  Next, the case where the document is conveyed in the foreign substance removal conveyance mode by the conveyance mode switching means 21 will be described with reference to FIGS. The same applies to the foreign substance removal conveyance mode until the registration roller pair 203 conveys the loop so as to form a loop.

  After a predetermined time T3 has passed in order to synchronize with the document reading timing by the imaging unit 5, the registration roller pair 203 and the paper discharge roller pair 204 are driven, and the document 1 is fed toward the document reading position 3. When the leading edge of the document 1 reaches the paper discharge roller pair 204, the paper discharge roller pair 204 is stopped for a predetermined time T5. As shown in FIG. 9, during this time, the document 1 conveyed at a constant speed by the registration roller pair 203 is bent so as to contact the document reading position 3 of the document glass 6.

  Then, the document 1 is conveyed while maintaining the state in contact with the document glass 6 by controlling the document conveyance speed of the paper discharge roller pair 204 and the registration roller pair 203 to be substantially equal. When the original 1 comes into contact with the foreign matter on the original glass 6, the foreign matter adheres to the original 1 or is moved from the original reading position 3 along the conveyance direction of the original.

  When the timing at which the trailing edge of the document 1 passes through the registration roller pair 203 is detected by the registration sensor 203 a, the registration roller pair 203 is stopped at that timing, and the document 1 is moved outside by the discharge roller pair 204. Transported and discharged. Even after the trailing edge of the document 1 has passed through the registration roller pair 203, at the time T6 when it is conveyed by the paper discharge roller pair 204, the document conveyance speed of the paper discharge roller pair 204 is previously set so as to maintain a predetermined resolution. Since the speed is controlled so as to be driven at the set constant speed, the document 1 is transported at a constant transport speed. When the discharge of the original 1 is confirmed by a discharge sensor 204a provided on the downstream side of the discharge roller pair 204, the discharge roller pair 204 is stopped.

  In the above-described foreign matter removal conveyance mode, a description has been given of the case where the discharge roller pair 204 is controlled to stop for a predetermined time so that the document 1 contacts the document glass 6 on the conveyance path. It may be either immediately after reaching the discharge roller pair 204 or immediately before. Further, instead of controlling the stop of the discharge roller pair 204 for a certain period of time, the discharge roller pair 204 is configured to bend by being controlled to drive at a lower speed than the conveying speed of the registration roller pair 203 for a certain period of time. It may be. In any case, this time is very small, and the change in the conveyance speed in the sub-scanning direction is very small, so that there is no great influence on the read image data.

  Next, based on FIGS. 1 and 6, a case where foreign matter is detected on the original glass 6 in the middle of the normal conveyance mode and the mode is switched to the foreign matter removal conveyance mode in the middle will be described. The registration roller pair 203 is activated after a predetermined time T3 after the paper feed roller pair 202 is driven and a loop is formed at the leading edge of the document 1, and the document 1 is directed toward the document reading position 3. Sent.

  When the leading edge of the document 1 is guided by the guide plates 8c and 8b and reaches the paper discharge roller pair 204, the document 1 is conveyed by both the registration roller pair 203 and the paper discharge roller pair 204 (T5). The conveyance speed of the original by the registration roller pair 203 is driven at a constant speed set in advance to maintain a predetermined resolution, and the conveyance speed by the discharge roller pair 204 is initially the conveyance speed by the registration roller pair 203. Is set faster than. Accordingly, the document 1 conveyed by the pair of rollers 203 and 204 is conveyed in a state of being separated upward from the document glass 6. At this time, since a slipping mechanism is provided on the drive roller side of the discharge roller pair 204, the document 1 is conveyed at the conveyance speed of the registration roller pair 203 as described above.

  Here, when a foreign matter is detected by the foreign matter detection unit 18 based on the image data read so far, the transport mode switching unit 21 switches from the normal transport mode to the foreign matter removal transport mode. The paper discharge roller pair 204 is stopped for a predetermined time T5, during which the original 1 conveyed by the registration roller pair 203 is bent and brought into contact with the original glass 6 as shown in FIG.

  Thereafter, the document transport speed of the paper discharge roller pair 204 and the registration roller pair 203 is controlled to be substantially constant, so that the document 1 is transported while a part of the document 1 remains in contact with the document glass 6. The foreign matter is removed by the contact portion.

  When the trailing edge of the document 1 has passed through the registration roller pair 203, the registration roller pair 203 stops, and the document 1 is conveyed only by the paper discharge roller pair 204. Thereafter, reading of the document in the foreign matter removal conveyance mode is continued until the removal of the foreign matter is detected.

  Furthermore, a case where the removal of the foreign matter is detected by the foreign matter detection unit 18 in the middle of the foreign matter removal transport mode and the mode is switched to the normal transport mode will be described with reference to FIGS. 1 and 7. As described above, the same is true until the registration roller pair 203 is conveyed so as to form a loop. After a predetermined time T3 has passed in order to synchronize with the document reading timing by the imaging unit 5, the registration roller pair 203 and the paper discharge roller pair 204 are driven, and the document 1 is sent toward the document reading position 3. When the leading edge of the document 1 reaches the paper discharge roller pair 204, the paper discharge roller pair 204 is stopped for a predetermined time T5. As shown in FIG. 9, during this time, the document 1 conveyed at a constant speed by the registration roller pair 203 is bent so as to contact the document reading position 3 of the document glass 6.

  Thereafter, the original 1 is conveyed while maintaining the state in contact with the original glass 6 by controlling the original conveying speed of the paper discharge roller pair 204 and the registration roller pair 203 to be substantially equal to each other (T6). ). When the original 1 comes into contact with the foreign matter on the original glass 6, the foreign matter adheres to the original 1 or is moved from the original reading position 3 along the conveyance direction of the original.

  In this state, when the removal of foreign matter is detected based on the image data read so far, the transport mode switching means 21 switches from the foreign matter removal transport mode to the normal transport mode. The conveyance speed of the paper discharge roller pair 204 is changed and controlled from the same speed as that of the registration roller pair 203 so as to be higher than the conveyance speed at time T5 in FIG. Therefore, the bending of the document 1 conveyed by the roller pairs 203 and 204 is gradually eliminated, and the document 1 is conveyed in a state of being separated upward from the document glass 6 (T6). Thereafter, the reading of the document in the normal conveyance mode is continued until a foreign object is detected.

  Hereinafter, the transfer mode switching operation by the transfer mode switching means 21 will be described with reference to the flowchart shown in FIG. When the print key of the operation unit is operated (S1), the shading correction plate 9 is read before the reading of the document 1 is started, and the foreign material detection unit 18 detects the foreign material at the document reading position 3 on the document glass 6. It is determined whether or not there is (S2).

  When foreign matter is detected on the original glass 6 (S2), image reading is started in the foreign matter removal mode (S6, S4). In the middle of reading the original 1 (S5), when the number of originals in which foreign matter is detected is less than a predetermined number (S7), it is determined that the foreign matter on the original glass 6 has been removed during the foreign matter removal conveyance mode. (S2), the mode is switched to the normal conveyance mode (S3), and the conveyance of the original 1 is continued in the normal conveyance mode until all the originals are read (S5). If the number of documents in which foreign matter is detected during document reading has reached a predetermined number or more (S7), it is determined that the foreign matter has not been removed depending on the foreign matter removal conveyance mode, and a service call is prompted to prompt the Reading ends.

  When no foreign matter is detected on the original glass 6 (S2), reading of the original 1 in the normal conveyance mode is started (S3, S4). After a predetermined time elapses (S5, S7), when no foreign matter is detected during the normal conveyance mode (S2), conveyance of the original 1 is continued in the normal conveyance mode until all originals are read (S5). After a predetermined time elapses (S5, S7), when a foreign matter is detected during the normal transport mode (S2), the mode is switched to the foreign matter removal transport mode (S6). In the middle of reading the original 1 in the foreign matter removal conveyance mode (S5), when the number of originals in which the foreign matter is detected is less than a predetermined number (S7), the foreign matter on the original glass 6 is in the middle of the foreign matter removal conveyance mode. If it is determined that the document has been removed (S2), the mode is switched again to the normal conveyance mode (S3), and the conveyance of the original 1 is continued in the normal conveyance mode until all the originals are read (S5). If the number of documents in which a foreign object is detected during document reading has reached a predetermined number or more (S7), it is determined that the foreign object has not been removed depending on the foreign material removal conveyance mode, and a service call is prompted to prompt the Reading ends.

  Another embodiment will be described below. In the above-described embodiment, as shown in FIG. 9, when a foreign object is detected on the original glass 6 before reading the original, the original 1 is conveyed while a part of the original 1 is in contact with the original glass 6. As shown in FIG. 10, the guide angle of the guide plate 8a for determining the entry angle of the document 1 to the document reading position 3 is set to a predetermined angle, as shown in FIG. The leading edge of the document 1 comes into contact with the document glass 6 on the front side of the document reading position 3, and the document 1 is conveyed in this state, so that the foreign material is removed by the leading edge of the document 1. By configuring as described above, it is possible to more effectively remove foreign matters.

  In the above-described embodiment, in order to bend the document 1 in the foreign matter removal conveyance mode, the driving of the discharge roller pair 204 is stopped for a certain time immediately after the document 1 reaches the discharge roller pair 204, and then the registration roller pair 203 Although the driving at the same speed has been described, in order to bend the document 1, the conveyance speed of the registration roller pair 203 is set to be higher than a predetermined sub-scanning speed for a predetermined time, and the conveyance speed of the discharge roller pair 204 is set. May be driven at a predetermined sub-scanning speed, and thereafter the registration roller pair 203 and the paper discharge roller pair 204 may be conveyed at a predetermined sub-scanning speed.

  In the above-described embodiment, the document reading apparatus mounted on the copying machine has been described. However, the document reading apparatus may be configured alone or mounted on the facsimile apparatus.

Cross-sectional explanatory diagram of a document reading device according to the present invention Control block diagram of document reading apparatus according to the present invention flowchart Timing chart in normal transport mode according to the present invention Timing chart in foreign substance removal conveyance mode according to the present invention Timing chart explaining switching from normal conveyance mode to foreign substance removal conveyance mode according to the present invention Timing chart for explaining switching from the foreign matter removal transfer mode to the normal transfer mode according to the present invention Cross-sectional explanatory view of the document reading unit in the normal conveyance mode according to the present invention Cross-sectional explanatory diagram of the document reading unit in the foreign matter removing and conveying mode according to the present invention Sectional explanatory drawing of the document reading part in the foreign substance removal conveyance mode by another embodiment

1: Document A1: Document feeding unit A2: Document discharge unit 202: Paper feed roller pair 203: Registration roller pair 204: Paper discharge roller pair 3: Document reading position 6: Document glass 8a: Guide plate 8b: Guide plate 9: Shading correction plate 18: foreign matter detection unit

Claims (3)

A document feeding unit that feeds a document toward a document reading position on the document glass, and a document discharge unit that discharges the document on a side facing the document feeding unit across the document reading position. A sheet-through-type document reading apparatus configured to include a document conveying unit and a document reading unit that reads image information of a document that passes through the document reading position,
When a foreign object is detected on the original glass by the original reading unit, the original conveyance mode of the original conveyed by the original conveyance unit is changed from the normal conveyance mode in which the original is conveyed away from the original glass. Provided with a transport mode switching means for switching to a foreign matter removal transport mode for transporting the original in contact with the glass,
In the foreign matter removing and conveying mode, the document conveying unit stops the document discharging operation in the document discharging unit or lowers the document discharging speed from the document feeding speed by the document feeding unit, and the document is the document. It is configured to bend until it comes into contact with the glass, and then the document discharge speed is controlled to be equal to the document feeding speed .
A document reading apparatus provided with a cleaning mechanism in the document discharge unit for removing foreign matter adhering to the document transported by the document transport unit .   The transport mode switching means switches from the foreign material removal transport mode to the normal transport mode when the document reading unit no longer detects a foreign material on the document glass while the document is transported in the foreign material removal transport mode. The document reading apparatus according to claim 1, wherein the document conveying unit is configured to be switched. The document feeding unit is provided with a guide plate capable of switching an angle of entry of the document to the document reading position, and the document transport unit is configured to move the document at the leading end portion of the document in the foreign substance removal transport mode. 3. The document reading apparatus according to claim 1, wherein the guide angle of the guide plate is switched so that the document glass is brought into contact with the document glass at a position closer to the front side and conveyed in that state.

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