JP5218265B2 - Image reading apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an image reading apparatus and an image forming apparatus applied to an image forming apparatus such as a facsimile, a scanner, a copier, and a multifunction peripheral.

  Image reading apparatuses are widely used alone, in combination with automatic document feeders, or in combination with image forming apparatuses. By the way, there is an image reading apparatus called a sheet-through method in which a document is transported in the sub-scanning direction, and the document being transported is read by a reading unit placed at a fixed position (for example, Patent Document 1). Patent Document 2, Patent Document 3, etc.). According to such a sheet-through method, the document passes while contacting the contact glass when reading, and therefore, it is inevitable that dust attached to the image surface side of the document adheres to the contact glass. There are many cases where garbage suddenly adheres. When this deposit adheres to the reading position of the contact glass, the influence appears in the read image signal, and the image is deteriorated. Dust and other deposits on the contact glass lead to image deterioration not only in the sheet-through method but also in any method, but are generated as dots in an image reading device that fixes the document and performs sub-scanning of the reading unit. On the other hand, in the case of a sheet-through type reading apparatus, a so-called vertical streak is formed which is connected in the sub-scanning direction, and the influence is much greater. Incidentally, an image reading apparatus equipped with both reading methods is also widely used. However, when a sheet-through reading is performed, the situation is exactly the same and vertical stripes are likely to occur.

In addition, it has been proposed to transport without contacting the contact glass (see, for example, Patent Document 4), thereby preventing dust from adhering and staying and suppressing noise generation. Alternatively, as disclosed in Patent Document 5, the contact glass is moved in the sub-scanning direction (same conveyance direction as the original), or as disclosed in Patent Document 6, platen glass (contact glass referred to in the present invention). There is known a method for detecting and dealing with dust from image data even during image reading by reciprocally moving the image in the sub-scanning direction or moving in one direction (the document conveying direction or the opposite direction).
However, as disclosed in Patent Document 5 or Patent Document 6, by moving the platen glass (contact glass) in the sub-scanning direction, the method of detecting dust from the read image data even during image reading. For example, if the dust on the contact glass is white (paper dust, etc.) for a white document, or if the dust on the contact glass is black for a solid black document, There is a problem that dust detection cannot be performed. In addition, the dust detection has a problem that the contact glass and the document are in contact with each other, and dust caught between them cannot be detected.

  The present invention has been made in view of the above circumstances, and is capable of detecting dust on the contact glass at a fixed reading position for reading a conveyed document and preventing image deterioration due to the dust. It is an object of the present invention to provide a reading apparatus and an image forming apparatus equipped with the reading apparatus.

In order to solve the above problems, according The invention according to claim 1, while conveying to fix the reading unit an original in contact glass and a non-contact, said corresponding to arranged the reading position below the contact glass In an image reading apparatus that reads an image at a reading position on a contact glass, in order to detect the presence or absence of dust at the reading position, an optical path of detection light is transmitted through the contact glass surface in a main scanning direction at the time of reading an original. A dust detection means using a transmission type optical sensor disposed in the apparatus, a moving means for moving the contact glass in a sub-scanning direction, a contact glass cleaning means for cleaning the contact glass, and a moving direction of the contact glass a upstream side, includes a dust containing portion provided in the support portion of the contact glass, and control means for controlling each portion of the apparatus, wherein the control Stage, the dust detection means, when detecting the dust on the document reading position by said moving means, to a position where the dust detecting means does not detect the dust, but moving the contact glass, there is no dust When the position cannot be detected, the reading of the document is stopped, the image reading is stopped, and then the contact glass is cleaned by the cleaning means while moving the contact glass in the sub-scanning direction, The dust container moves the contact glass to a position between the reading position and the cleaning unit and close to the cleaning unit . This makes it possible to detect dust on the reading area extending in the main scanning direction and prevent occurrence of vertical stripes even during image reading regardless of the document color or dust color.
Further, the invention of claim 2, the image reading apparatus according to claim 1, the light receiving unit element for reading the original document is a CCD or CIS, as sending a light source of the transmissive optical sensor, reading the read originals A light transmitting light source having a wavelength that does not affect the light receiving performance of the element or has little influence is used. Since the optical path of the transmission optical sensor (photo interrupter) is provided on the reading position, it is caused by the transmission optical sensor by using a light transmission light source that does not affect or hardly affects the CCD and CIS. This prevents deterioration of the read image due to reflected or scattered light.

Further, in the image reading apparatus according to claim 1 or 2, in the image reading apparatus according to claim 1 or 2, after the image reading is stopped, an alert for prompting cleaning of the contact glass is displayed on an operation panel or the like. A warning means is provided .

According to a fourth aspect of the present invention, in the image reading apparatus according to any one of the first to third aspects, the image reading apparatus includes an automatic document conveying device that sequentially feeds documents from a bundle of documents to the image reading device. Features. Images can be read continuously, and even during scanning, dust detection is possible regardless of the color of the document or the color of dust, and vertical streaks can be prevented.

The invention of claim 5 is provided with a image forming means for forming an image on a recording medium, you comprising the image reading apparatus according to any one of claims 1 to 4.

  According to the present invention, an image reading apparatus capable of detecting dust on a contact glass at a reading position in an image reading process of a sheet through method and preventing image deterioration due to the dust, and an image forming apparatus equipped with the image reading apparatus. Can be provided.

1 is a cross-sectional view schematically showing a copying machine which is an embodiment of an image forming apparatus according to the present invention. It is sectional drawing of ADF in embodiment. It is an electrical equipment block diagram in an embodiment. It is a perspective view which shows the example of attachment of contact glass. It is sectional drawing which shows the structure of contact glass and a reading opening part. It is sectional drawing which shows the drive mechanism of contact glass. It is a figure which shows the photo interrupter in embodiment, (a) is a perspective view, (b) is a top view. (A)-(c) is a figure explaining the permeation | transmission state of a photo interrupter. (A)-(c) is a figure explaining the state which refuse adhered. (A) And (b) is a figure explaining dust detection and a movement of contact glass. (A) And (b) is a figure explaining the state to which a lot of refuse adhered. (A)-(e) is a figure explaining the structure and operation | movement of a cleaning means. It is a flowchart explaining operation | movement of embodiment. It is a flowchart explaining operation | movement of embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view schematically showing an electrophotographic copying machine as an embodiment of an image forming apparatus according to the present invention. The copying machine includes an image reading apparatus according to the present invention including an automatic document feeder (hereinafter referred to as ADF). The present invention can be applied to a facsimile machine, a printer device, a multifunction machine having a copying function and a facsimile function, etc. in addition to a copying machine as an image forming apparatus.
The copying machine of this embodiment mainly includes a reading unit 600 that reads a document, an image forming unit 610 that forms an image, an ADF 620, a document discharge tray 630 that stacks documents sent from the ADF 620, and paper feed cassettes 640 to 670. A sheet feeding unit 680 and a sheet discharge unit 690 that stacks recording sheets are included. An image reading unit (image reading apparatus) according to the present embodiment is configured by a reading unit 600 included in an upper part of an image forming unit (copier main body) 610 and an ADF 620 mounted on the upper surface of the image forming unit 610. Is done.

An ADF (automatic document feeder) is a device that is widely used in an apparatus that reads a document to be read to a fixed reader unit and reads an image while conveying the document at a predetermined speed. The basic configuration, operation, and action of the ADF in the present embodiment will be described based on the cross-sectional view of the ADF device shown in FIG. 2 and the electrical equipment block diagram shown in FIG. FIG. 3 shows a controller 100 that controls the ADF 620 and a main body control unit 212 on the image forming unit 610 side (detailed configurations thereof will be described in detail later).
The ADF 620 primarily collates and aligns a fed document with a document setting unit A that sets a bundle of documents, a separation feeding unit B that separates and feeds the documents one by one from the set document bundle. And a registration portion C that pulls out and conveys the original after alignment, a turn portion D that turns the conveyed original and conveys the original surface toward the reading side (downward), and an image of the original on the contact glass 41. A reading conveyance unit E for reading from below, a reverse switchback for reading the second side (back side) of the document, or a reverse discharge unit (switchback unit) F for discharging the document outside the apparatus, A stack unit (paper discharge unit) G for stacking and holding documents is provided.

The document setting section A includes a document set table (mounting table) 1 on which the document bundle P is placed, a document stopper 2 on which the leading edge of the document placed on the document set table 1 is abutted, and a document on the document set table 1. A document set filler 31 for detecting that the document is placed, document length detection sensors 20 to 22 for detecting the size of the document placed on the document set table 1, the document set sensor 19, and the document set table 1 are set. And a document thickness information sensor 43 for detecting the thickness of the document bundle P.
The separation feeding unit B includes a pickup roller 3 that calls the originals of the original bundle P, HP (home position) sensors 33 and 34 that detect the states of the pickup roller 3 and the original stopper 2, and a conveyance path for the called originals. A separation roller 4 and a sheet feeding belt 5 that are separated and conveyed one by one toward the sheet, and a separation sensor 23 that detects a document fed from the separation roller 4 and the sheet feeding belt 5.
The registration unit C detects pullout rollers (conveying means) 6 and 7 that convey the document conveyed from the separation feeding unit B toward the turn unit D, and the document conveyed toward the pullout rollers 6 and 7. And a plurality of document width sensors 25 (25a to 25e) for detecting the length of the document conveyed from the pull-out rollers 6 and 7 in the width direction.

The turn part D includes a conveyance roller 45, a reading inlet sensor 26 provided close to the conveyance roller 45, and a reading inlet roller (abutting roller) that conveys the document conveyed from the registration part C toward the reading position of the reading glass 41. And a registration sensor 27 that detects a document conveyed from the reading entrance rollers 8 and 9. The reading entrance sensor 26 is arranged at a position on the right side (back side) with respect to the transport direction. In the conveyance path between the document width sensor 25 and the reading entrance sensor 26, no driving means such as a conveyance roller is provided.
The reading conveyance unit E is configured to read a document conveyed from the reading opening rollers 8 and 9 between the reading glass 41 and the white background plate on a reading unit 28 on the upper surface of the reading unit. A reading inlet guide 40 that guides the document, a reading exit roller 10 and a pressure roller 11 that convey the document that has passed through the reading opening 28 toward the reverse paper discharge unit F, and a document that has passed through the reading outlet rollers 10 and 11. A paper discharge sensor 29 to be detected, and a completed stamp unit 106 for impressing a reading end mark on a document that has been read are provided.
The reverse paper discharge unit F is transported to the switchback path by the branch claw 15 that distributes the transport destination of the document transported from the reading exit rollers 10 and 11 to either the reverse path or the switchback path. A reversing roller pair 16 and 17 for switching back the document, a reversing sensor 30 provided in the vicinity of the reversing roller pair 16 and 17, a paper discharge roller 12 and paper discharge driven rollers 13 and 18 are provided.

The stack unit G includes a paper discharge tray 630 on which originals discharged from the paper discharge roller 12 and the paper discharge driven roller 13 are stacked.
The ADF 620 can be opened and closed with respect to the image forming unit 610 via a hinge mechanism (not shown). In the pressure plate mode, the ADF 620 is lifted up, and the sheet original (or book original) placed on the contact glass 105 on the same surface as the contact glass 41 on the upper surface of the main body is pressed by the white member (pressure plate) on the lower surface of the ADF 620. Read. A white document guide member 112 is attached to the ADF 620, and positioning guide members are attached to the image forming unit 610 before and after the contact glass 105.
The controller 100 that controls the ADF 620 is provided so as to be able to communicate with the main body control unit 712 via an I / F (interface) as shown in FIG. On the input side of the controller 100 are a document thickness information sensor 43, a registration sensor 27, a document set sensor 19, a paper discharge sensor (reading exit sensor) 29, a reading entrance sensor 26, document length sensors 20 to 22, and a separation sensor. 23, outputs from a home position sensor (pickup HP sensor 33, claw HP sensor 34), paper feed cover open / close sensor 32, and abutment sensor 24 are connected.

Further, a pickup motor, a paper feed motor, a reading motor, a paper discharge motor, a bottom plate raising motor, a lower reversing motor, an upper reversing motor, a double-side switching claw driving solenoid, and a slip detection sensor are connected to the output side of the controller 100. However, the driving mechanism of the ADF 620 is driven, but since it is not directly related to the present invention, the detailed description is omitted in this specification. In addition, the controller 100 is provided with a skew amount calculation means and a conveyance control means for controlling each of the above-described conveyance motors, but illustration and description thereof are omitted.
As shown in FIG. 3, the image forming unit 610 includes a main body control unit 712 that controls the entire apparatus, and the main body control unit 712 is connected to the ADF 620 via a communication I / F (not shown). The transmitted image data and various signals are received. Further, the main body control unit 712 performs drive control of the reading unit 600, display control in the operation unit 711, and the like based on the information indicated by the signals thus received and input, and also provides an operation mode signal and paper feed to the ADF 620. Various control signals including a start signal are transmitted to instruct the ADF controller 100 to control the transport operation of the ADF 620. The operation unit 711 includes various button keys (not shown) such as a start button and a numeric keypad, and a display unit 711a using an LCD display, etc., for setting each operation mode and starting / stopping the operation. An instruction can be made by a user operation.

The original bundle P to be read is set on the original table 1 in the case of single-sided reading. When the original surface is facing upward, the front end of the original is a stop claw 2 (the state at the time of setting is a two-dot chain line) Set it against (shown). Further, the width direction of the document bundle P is positioned in a direction perpendicular to the conveyance direction by a side fence (not shown). At this time, an outline of the length in the document transport direction is determined by the document length detection sensors 20 to 22 provided on the document table surface (at least a sensor capable of determining whether the document size is vertical or horizontal is provided. )
A plurality of document width sensors 25 in the registration unit C are arranged in a direction (depth direction) orthogonal to the conveyance direction (25a to 25e), and detect the size in the width direction perpendicular to the conveyance direction of the document conveyed by the pull-out roller 6. To do. The length of the document in the conveyance direction is detected from the motor pulse by reading the leading and trailing edges of the document with the butting sensor 24.
When a print key is pressed from a main body operation unit (not shown) and a document feed signal is transmitted from the main body control unit to the ADF control unit, the set claw 2 is retracted downward by a set claw driving motor (not shown) At the same time, the pickup roller 3 is lowered so as to press the document bundle P from above. The pickup roller 3 is driven to rotate by a normal rotation of a paper feed motor 802 (not shown), and picks up several (ideally one) originals on the original table 1. The rotation direction is a direction in which the uppermost document is conveyed to the sheet feeding port.

The paper feeding belt 5 is driven in the paper feeding direction by the forward rotation of the paper feeding motor 802, and the reverse roller 4 is driven to rotate in the reverse direction to paper feeding to separate the uppermost document from the original document below it, Only a document can be fed. The original separated into one sheet by the action of the paper feeding belt 5 and the reverse roller 4 is further fed by the paper feeding belt 5, and the leading edge is detected by the abutting sensor 24 and further abuts against the pull-out roller 6 which is stopped. .
Thereafter, the sheet feeding motor 802 is stopped in a state in which it is fed by a predetermined amount from the detection of the abutting sensor 24 and as a result is pressed against the pull-out roller 6 with a predetermined amount of bending. As a result, the driving of the paper feeding belt 5 is stopped. At this time, by rotating the pickup motor 801, the pickup roller 3 is retracted from the upper surface of the original and the original is fed only by the conveying force of the paper feeding belt 5, so that the front end of the original enters the nip between the pull-out roller 6 and the driven roller 7. Then, tip alignment (skew correction) is performed.

The pull-out roller 6 has a skew correction function and is a roller for conveying the skew-corrected document after separation to the reading entrance roller 8, and is driven by the reverse rotation of the paper feed motor 802. At this time (at the time of reverse rotation of the paper feed motor), the pull-out roller 6 is driven, but the pickup roller 3 and the paper feed belt 5 are not driven.
Due to the rotational drive of the reading entrance roller 8, the original is fed into a reading opening 28 which will be described in detail later. When the document is transported to the reading entrance roller 8 by driving the pull-out roller 6, the processing time for sending the document to the reading unit is set faster than the reading speed to shorten the processing time.
The main body side reading unit H of the embodiment will be described. An upper portion of the image forming unit (copier main body) 610 is a reading unit 600, and a contact glass 105 (see FIG. 2) made of a translucent member is provided on the upper surface of the reading unit 600. A contact glass (also referred to as slit glass) 41 made of a light-transmitting member having a smaller area than the contact glass 105 is provided on the upper surface of the main body adjacent to 105 (see FIG. 2). In addition, a reading optical system and a reading mechanism section described later are provided inside the reading unit 600.

An example of attaching the contact glass 41 that is movably attached to the image forming unit 610 will be described with reference to FIGS. In this embodiment, the contact glass 41 of the reading unit 600 is fixed to the bracket 120 with an adhesive tape (see the perspective view of FIG. 4), and the image forming unit 610 is interlocked with the bracket (fixing member) 120. On the other hand, it is configured to be movable in the sub-scanning direction.
Further, downstream of the contact glass 41, an original scooping guide 102 is provided with a step as shown in the cross-sectional view of FIG. A flexible member (not shown) such as Mylar is provided on the upper surface of the document scooping guide 102, and one tip of the flexible member is in contact with the downstream end surface of the contact glass 41. As the flexible member, for example, a polyester film having a smaller coefficient of friction with the document than that between the other conveying member and the document, or the surface is treated with a so-called low friction treatment (Teflon (registered trademark)). A coated elastic member (rubber material), or the like is used.
Further, a rack gear 210 is attached to the back surface of the bracket 120 as shown in the cross-sectional view of FIG. 6, and the pinion gear 211 is rotated with respect to the sub-scanning direction by rotating the bracket 120 with a driving device not shown in the drawing. And can be moved.

As shown in FIG. 1, an exposure lamp (light source) 81a for illuminating a document on the contact glass 105 or the contact glass 41 is provided in the reading unit 600 as a reading optical system constituting a main body side reading unit. The first mirror 81b, the second mirror 81c, the third mirror 81d that reflect the light reflected from the document, the lens 81e that forms the light reflected from the third mirror 81d, and the lens 81e form an image. And a CCD (Charge-Coupled Devices) image sensor 81f that converts the light into an electrical signal, and is supported by a reading mechanism (not shown).
The exposure lamp 81a and the first mirror 81b are attached to a first traveling body (not shown), and the second mirror 81c and the third mirror 81d are attached to the second traveling body, and the first traveling body and the second traveling body. The body is movable in the left-right direction in FIG. 1 along the contact glass 105 and the contact glass 41. In the case of sheet-through mode reading in which an original conveyed through the contact glass 41 and read through the contact glass 41 is read, the exposure lamp 81a and the first mirror 81b are placed below the contact glass 41 (the reading position in FIG. 5). 28P) and reading is performed.

Reflected light from the document surface irradiated by the exposure lamp 81a enters the CCD image sensor (reading element) 81f through the first mirror 81b and the lens 81e, forms an image, and synchronizes with the CCD driving clock. Thus, an image signal for one line is obtained and sent to the main body control unit 212. Incidentally, at the time of reading the document fixing mode, the first traveling body and the second traveling body are moved in the left-right direction in FIG. 1 below the contact glass 105 and can read the document placed on the contact glass 105. is there.
The apparatus described in the embodiment includes a set of (transmission type) photo interrupters 200 that are dispersedly arranged at both ends of the contact glass 41 in the main scanning direction as dust detection means. The photo interrupter 200 is divided into a light emitting unit (light source) and a light receiving unit (see a perspective view of FIG. 7). The position at which the light of the photo interrupter 200 is emitted is positioned on the orthogonal line of the reading position 28P with respect to the sub-scanning direction, and is positioned on the contact glass 41 with respect to the vertical direction.

A state in which light emitted from the light emitting unit is set to be received by the light receiving unit and an output is obtained from the light receiving unit is referred to as a transmission state (see FIG. 8). When an object that blocks light is placed between the light emitting unit and the light receiving unit, light emitted from the light emitting unit does not reach the light receiving unit. Such a state is referred to as a light shielding state (see FIG. 9).
In the transmission state (FIG. 8), it can be determined that there is no dust on the reading position 28P of the contact glass 41. On the other hand, if dust stays at the reading position 28P on the contact glass 41, it is blocked by the light emitted from the light emitting unit and dust (FIG. 9), so that the light does not reach the light receiving unit. . It is determined that there is dust on the reading position 28P of the contact glass 41.
In addition, since the optical path of the photo interrupter 200 is provided on the reading position 28P, a light source having a wavelength or a light source having a sharp directivity that does not affect or hardly affects the CCD or CIS can be used for the photo interrupter 200. preferable.

In the present embodiment, in order to properly detect dust, on the ADF side, the document is lifted from the contact glass 41 in a region opposite to the reading position (so-called ADF side reading unit), that is, in a non-contact state. In addition, the document is transported in a state where the document is above the optical path of the photo interrupter 200, and is combined with the above-described dust detection mechanism. Thereby, even during image reading, dust detection is possible regardless of the color of the original or the color of the dust (see FIG. 5 and the like).
Incidentally, in the dust detection disclosed in Patent Document 6, the contact glass 41 and the document are in contact with each other, and dust caught between them cannot be detected. On the other hand, according to the present embodiment, by using the mechanism as described above, the above-described conventional problem is solved, and dust on the contact glass 41 can be detected with high reliability.

Next, the reading process will be described. In the apparatus of this embodiment, dust detection on the contact glass 41 is performed prior to reading and during reading. That is, when it is on the reading position as shown in FIG. 10A and the photo interrupter (detection means) 200 determines that there is dust, the contact glass 41 is sub-scanned as shown in FIG. 10B. It moves in the direction of the directional arrow and continues to move to a position where the photo interrupter 200 is in a transmissive state (a position where the dust detection means does not detect dust). By setting the transmission state, there can be no dust on the reading position of the contact glass 41, so that subsequent vertical stripes can be prevented.
When the leading edge of the document is detected by the reading entrance sensor 26, before the leading edge of the document enters the reading entrance roller 8, the document feeding speed is started to decelerate so that the document feeding speed is the same as the reading feeding speed. The reading entrance roller 8 and the reading exit roller 10 are driven by rolling. When the registration sensor 27 detects the leading edge of the document, it decelerates over a predetermined conveyance distance, temporarily stops before the reading position 28P (registration stop), and transmits a main body controller registration stop signal.

Subsequently, when a reading start signal is received from the main body control unit, the document whose registration has been stopped is accelerated and conveyed so as to rise to a predetermined conveying speed until the leading edge of the document reaches the reading position. At the timing when the leading edge of the document detected by the pulse count of the reading motor reaches the reading unit, a gate signal indicating an effective image area in the sub-scanning direction is transmitted to the main body control unit until the trailing end of the document passes through the reading unit. The image signal read by the CCD image sensor (reading element) 81 f is sent to the main body control unit 212. Thus, the document that has passed through the reading opening 28 is conveyed by the reading exit roller 10 and the paper discharge roller 12 and discharged to the paper discharge tray 630.
In the present embodiment, dust detection processing and movement processing are performed according to the result prior to the start of document reading, but dust detection is also continuously performed during document reading. During the reading of an original, when the dust suddenly adheres to the reading position on the contact glass 41 and the dust is detected (the photo interrupter 200 is in a light-shielding state), the contact glass 41 is kept until the photo interrupter 200 is in a transmissive state. Are moved in the sub-scanning direction. In this case, there is a case where a short vertical stripe occurs due to dust on the reading position until the transmission state is reached. In order to reduce this, noise reduction processing is also performed in the image processing unit of the main body.

Since it is possible to specify at which position in the sub-scanning direction a vertical streak is generated from the timing when the photo interrupter 200 is in the light-shielded and transmissive state during document image reading, noise components due to dust can be obtained from document reading. Therefore, it is possible to easily remove noise components due to dust from image data, and to prevent occurrence of vertical stripes. Since this noise component removal process is a known technique, the description thereof is omitted in this specification.
In the present embodiment, different processing is also used as processing when dust is detected. That is, a warning means for urging the cleaning of the contact glass is provided. As shown schematically in FIG. 11, when a plurality of dusts or dusts long in the sub-scanning direction adhere, In some cases, however, the photo interrupter 200 cannot be transmitted. In this case, the reading of the document is stopped and an alert is issued to the operation panel or the like. Accordingly, by prompting the operator to clean the contact glass 41, dust on the contact glass 41 can be removed, and vertical streaks can be prevented in the subsequent image reading process.

As a cleaning means for cleaning the contact glass 41, in the embodiment, as shown in FIG. 12, a cleaning member 220 is attached below the left scale 103 of the contact glass 41, and a cleaning instruction button on the operation panel is pressed. When the case is detected, the movement shown in (a) to (e) is performed. That is, the contact glass 41 is moved to the upstream side by the control of the controller 100 to the position shown in FIG. With such a configuration, the surface of the contact glass 41 can be cleaned by being scraped off by the dust storage space 221 in the bracket 120.
FIG. 13 shows a control flowchart of the dust detection and glass movement described above. Along with this control, document conveyance control and image reading control at the reading unit are performed. These other controls are widely known, and publicly known patent documents also describe this embodiment. Since the case of the equivalent configuration is described in detail, it will not be described here.

In FIG. 13, when reading JOB is started, irradiation of photo interrupter detection light is started (step; S01), and whether or not the photo interrupter detection light is transmitted by the control unit based on the signal of the light receiving unit. (Whether or not the contact glass is at the current position and there is dust on the reading position) is determined (S02).
When the detection light of the photo interrupter is in a transmissive state (S02: Yes), the original reading process is started (S03), and the read data is sent when the image for the specified read is read (S04). Next, it is determined whether reading of the entire reading area is completed (S05), and if an unread portion remains (S05: No), the process returns to step (S02). If reading of all the specified areas is completed by repeating the above (S05: Yes), the JOB for one original is completed. If a plurality of sheets are continuously read, the processing from step (S01) is repeated for reading the next document.

On the other hand, if the photo interrupter detection light is not obtained in step (S02) (S02: No), the contact glass is removed until the photo interrupter passes state (stores the current reading position in the sub-scanning direction). It is moved (S06), and it is monitored that the photo interrupter becomes conductive (S07). When the detection light from the photo interrupter is in a transmissive state (S07: Yes), during reading, the processing range for removing streak noise in the sub-scanning direction is notified (S08), and the process proceeds to (S03). Start or continue the reading process.
If it is in the blocking state where the detection light of the photo interrupter cannot be obtained in step (S07) (S07: No), it is determined whether the contact glass moves (S09), and if it is not the moving limit (S09: No). The process returns to step (S06) again, but when the movement limit is reached with the photointerrupter blocked (S09: Yes), reading of the document is stopped, and the warning unit displays a warning on the operation panel (S10). ).
Thereafter, when there is a waiting operation for the contact glass cleaning instruction operation by the operator, the glass cleaning means is driven to clean the contact glass (S11), and then the processing from step (S02) is repeated.

As described above, the image signal read by the image reading apparatus is sent to the image forming unit 610, and an image corresponding to the image data is formed. A well-known image forming process in the image forming unit 610 will be briefly described. Inside the image forming unit 610, a photoconductor 611 which is an image carrier is disposed. The photosensitive member 611 is rotated in the clockwise direction in the drawing, and the charging device 612 charges the surface to a predetermined potential. Further, the writing unit 613 emits a laser beam L that is light-modulated in accordance with image information read by the reading unit 600, and the surface of the charged photosensitive member 611 is exposed with the laser beam L, whereby the photosensitive member is exposed. An electrostatic latent image is formed on the surface of 611.
The electrostatic latent image is developed by the developing device 614 and then transferred to the recording medium S fed between the photosensitive member 611 and the transfer device 615 by the opposing transfer device 615. The surface of the photoreceptor 611 after the toner image transfer is cleaned by a cleaning device 616.
A plurality of paper feed cassettes 640 to 670 arranged at the lower part of the image forming unit 610 contain recording media S such as paper or a bundle thereof, and the recording media S are sent out from any of the paper feed cassettes 640 to 670. Then, the toner image formed on the surface of the photoreceptor 611 as described above is transferred to the surface of the recording medium S. Next, the recording medium S is passed through the fixing device 617 in the image forming unit 610, and the toner image transferred to the surface of the recording medium S by the action of heat and pressure is fixed. The recording medium S that has passed through the fixing device 617 is conveyed by the discharge roller pair 618, discharged to the discharge tray 690, and stacked.

As described above, according to the present embodiment, as described above, the contact glass (platen glass) 41 found in the prior art disclosed in Patent Document 5 and Patent Document 6 is moved in the sub-scanning direction. In the method of detecting dust from image data even during image reading, for example, when white dust is white on the contact glass (paper dust, etc.) or contact with black solid documents. When the dust on the glass is black, it is possible to solve the problem that dust cannot be detected from the image data, and it is possible to more reliably detect dust and prevent vertical streaks due to dust.
In addition to the above-described configuration, a cleaning unit that automatically cleans the contact glass 41 may be provided instead of the above-described warning unit or in combination with the warning unit. The cleaning means in that case may have the same configuration as already shown in FIG.
That is, the cleaning member 220 is attached below the left scale 103 of the contact glass 41. The control unit autonomously controls the contact glass 41 to move upstream to the illustrated position under a predetermined condition (described later). By the movement, the dust on the contact glass is scraped off into the dust storage space 221 in the bracket 120, and the surface of the contact glass 41 can be cleaned.

FIG. 14 shows a control flowchart of dust detection, glass movement, and glass cleaning processing in this case. In FIG. 14, the processing steps assigned with the same processing numbers (step numbers) as in FIG. 13 are the same processing, the processing of steps: S01 to S09 is common, and only the processing of step (S12) is different.
When reading job is started, detection light irradiation of the photo interrupter is started (step; S01), and whether or not the detection light of the photo interrupter is in a transmission state by the control unit based on the signal of the light receiving unit (contact) It is determined whether the glass is at the current position and whether there is dust on the reading position (S02).
When the detection light of the photo interrupter is in a transmissive state (S02: Yes), the original reading process is started (S03), and the read data is sent when the image for the specified read is read (S04). Next, it is determined whether reading of the entire reading area is completed (S05), and if an unread portion remains (S05: No), the process returns to step (S02). If reading of all the specified areas is completed by repeating the above (S05: Yes), the JOB for one original is completed. If a plurality of sheets are continuously read, the processing from step (S01) is repeated for reading the next document.

On the other hand, if the photo interrupter detection light is not obtained in step (S02) (S02: No), the contact glass is removed until the photo interrupter passes state (stores the current reading position in the sub-scanning direction). It is moved (S06), and it is monitored that the photo interrupter becomes conductive (S07). When the detection light from the photo interrupter is in a transmissive state (S07: Yes), during reading, the processing range for removing streak noise in the sub-scanning direction is notified (S08), and the process proceeds to (S03). Start or continue the reading process.
If it is in the blocking state where the detection light of the photo interrupter cannot be obtained in step (S07) (S07: No), it is determined whether the contact glass moves (S09), and if it is not the moving limit (S09: No). The process returns to step (S06) again. If the movement limit is reached with the photo interrupter shut off (S09: Yes), reading of the document is stopped, the glass cleaning means is automatically driven to clean the contact glass (S12), and then the step ( The processing from S02) is repeated.

Also in the case of the above-described control, a warning display by a warning means or a sound of a warning sound (step in FIG. 11; S10) may be added as a notification operation. In the case of a copying machine, the image signal read by the image reading device is sent to the image forming unit 610 as described above, and an image corresponding to the image data is formed.
The above-described embodiment shows an example of a preferred embodiment of the present invention, and the present invention is not limited thereto, and various modifications can be made without departing from the scope of the invention. is there. For example, the contact glass 41 is configured integrally with the contact glass 105, and an appropriate guide member and driving mechanism are adopted in accordance with the contact glass 41, so that the integrated contact glass is moved, and vertical streaks are generated during sheet-through reading. Can be prevented. In addition, a CIS (Contact-type Image Sensor) may be used as the image reading element.

  DESCRIPTION OF SYMBOLS 1 Document table, 2 Stop claw, 3 Pickup roller, 4 Reverse roller, 5 Paper feed belt, 6 Pull-out roller (conveying means), 7 Driven roller (pull-out roller), 8, 9 Reading entrance roller (butting roller), 10 , 11 Reading exit roller, 12, 13 Paper discharge roller, 14 Paper discharge tray, 20-22 Document length detection sensor, 24 Abutting sensor, 25 Document width sensor, 26 Reading entrance sensor, 27 Registration sensor, 28 Reading opening (Reading unit), 28P reading position, 41 contact glass, 100 ADF controller, 103 left scale, 120 bracket, 200 photo interrupter, 210 rack gear, 211 pinion gear, 220 cleaning member, 221 garbage storage space, 600 reading unit, 610 image Forming unit (copier main body), 620 automatic document feeder (ADF), 640-670 sheet feeding cassette, 680 sheet feeding unit, 690 sheet ejection unit, 611 photoconductor, 612 charging unit, 613 writing unit, 614 developing unit, 615 transfer device, 616 cleaning device, 711 main body operation unit, 711a display unit, 712 main body control unit, P document, S recording medium

JP 2007-331940 A JP 2008-50132 A Japanese Patent No. 4235124 JP-A-8-123157 Patent 4097876 JP 2006-173791 A

Claims (5)

While fixing the reading unit conveys the document by the contact glass and the non-contact, in the image reading apparatus which performs image reading in the reading position on the contact glass corresponding to arranged the reading position below the contact glass,
In order to detect the presence / absence of dust at the reading position, dust detection means using a transmissive optical sensor arranged so that the optical path of the detection light is transmitted through the contact glass surface in the main scanning direction during document reading. When,
Moving means for moving the contact glass in the sub-scanning direction;
Contact glass cleaning means for cleaning the contact glass;
A dust storage part provided on the upstream side of the contact glass in the moving direction, provided in the support part of the contact glass;
Control means for controlling each part of the device,
Wherein, said dust detecting means, when detecting the dust on the document reading position by said moving means, to a position where the dust detecting means does not detect the dust, but moving the contact glass, dust If the position where there is no mark is not detected, stop scanning the document,
After stopping the image reading, the contact glass is cleaned by the cleaning means while moving the contact glass in the sub-scanning direction, and the dust storage portion is between the reading position and the cleaning means and the cleaning is performed. An image reading apparatus, wherein the contact glass is moved to a position close to the means.   The light-receiving element for reading a document is a CCD or CIS, and a light-transmitting light source having a wavelength that does not affect the light-receiving performance of the document-reading element or has a small influence is used as the light-transmitting light source of the transmission optical sensor. The image reading apparatus according to claim 1, wherein the image reading apparatus is used. 3. The image reading apparatus according to claim 1, further comprising: a warning unit that performs a notification such as displaying an alert for prompting cleaning of the contact glass on an operation panel or the like after the image reading is stopped . 4. The image reading apparatus according to claim 1 , further comprising an automatic document feeder that sequentially feeds documents from a document bundle to the image reading device. 5. An image forming apparatus comprising: an image forming unit that forms an image on a recording medium; and the image reading apparatus according to claim 1 .

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