JP4440978B2 - Image reading device - Google Patents

Description

  The present invention relates to an image reading apparatus that obtains image light by exposing and scanning a document surface, and more particularly, to an image reading apparatus that can expose and scan a document conveyed at a constant speed along a contact glass to obtain image light. .

  In a conventional image reading apparatus, a document fixing / optical system moving method (scanning method) for exposing and scanning a document, and a document moving / optical system fixing method (sheet through method) for moving the document at a predetermined speed and exposing it. Furthermore, it is well known that there are an analog type used in a general image reading apparatus and a digital type using an image sensor such as a CCD. Recently, a digital type document moving / optical system fixing method which is advantageous for reading a large document and performing various image processing thereafter has been widely employed.

  In the analog image reading apparatus, both of these types are exposed in a slit area having a width of 5 to 10 mm. In this slit area, a latent image is not formed on the photosensitive member unless the original and the photosensitive member are moved in synchronization. For example, if dust adheres or stays on the contact glass, the original is fixed and the optical system is moved. In the method, it becomes a black spot corresponding to the size of dust, and in the document movement / optical system fixed method, it becomes a blurred latent image, so even if it is developed, it does not become a head image as a clear image, It doesn't matter so much.

  However, in the case of a digital document moving / optical system fixing method, when the slit exposure area (hereinafter referred to as reading exposure width) is narrow, for example, at a reading density of 400 dpi, the reading exposure width is 25.4 / 400 = 0.0635 mm. Since it becomes very narrow, if dust with a size of 0.0635 mm or more adheres to this portion, it will be read continuously as black data regardless of the image on the document. As described above, when a document is read in a state where dust is attached and stays, portions corresponding to the dust are sequentially read in the sub-scanning direction, so that an abnormal image (including so-called black streaks) is likely to occur.

  In order to solve such problems, for example, in the image reading apparatus described in Japanese Patent Application Laid-Open No. 8-123157, a document is transported in a state where it floats from the contact glass to prevent dust from adhering and staying in the exposure unit. ing.

  However, in the image reading apparatus, since the leading edge and the trailing edge of the document are in contact with the contact glass, it is not possible to reliably prevent the adhesion and dirt of dust.

  The object of the present invention is to improve such problems and reduce the occurrence of black streaks caused by dust adhering to the contact glass (original platen) with a digital type document movement / optical system fixing method, which is favorable. An object of the present invention is to provide an image reading apparatus capable of obtaining read image data.

According to the first aspect of the present invention, the reading unit includes a contact-type sensor for reading an image, and a pressing roller that serves as a white reference and conveys the original while pressing the document against the contact-type sensor. an image reading apparatus performs image reading while conveying the original, a pair of support members arranged in the conveying direction upstream side and the downstream side of the document across the contact-type sensor, the pressing and the contact-type sensor An original plate that is sandwiched between rollers and spans between the pair of support members and includes the contact-type sensor so as to form a flat surface from the upstream side to the downstream side in the document conveyance direction and moves in the sub-scanning direction. a transparent sheet of置用, provided on the side of the contact-type sensor relative devoted position the document pushes the contact-type sensor is disposed, and the sheet feeding means feeding the transparent sheet, before Provided on the side of the contact-type sensor against against which position press the document in close contact type sensor is disposed, and a sheet winding means for winding the unwound transparent sheet, fed by the sheet feeding means in a predetermined cycle Control means for winding the transparent sheet by the sheet winding means, and performing image reading by relatively moving the contact sensor and the reading position of the transparent sheet in the sub-scanning direction. .

The image forming apparatus according to claim 2 , further comprising: an image reading unit that reads an image of a document; and an image forming unit that forms an image of the document read by the image reading unit on a predetermined sheet. The image reading apparatus according to claim 1 is used as means .

According to the first aspect of the present invention, in the sheet-through-type image reading apparatus provided with a contact type sensor for image reading and a white reference pressing roller in the reading unit, the reading position of the contact type sensor and the transparent sheet is provided. Are moved relative to each other to perform image reading, so that the occurrence of abnormalities such as black streaks can be suppressed and the image quality can be improved.

Further, according to the first aspect of the invention, the sheet feeding means, since moving the transparent sheet in the sub-scanning direction, by the movement of the transparent sheet, the original can be prevented from damage or conveying jam occurs.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[First Embodiment]
The image reading apparatus 30 according to the present invention includes a main body 60 and an automatic document feeder 50 as shown in FIG. The main body 60 includes a reading unit 80, and the automatic document conveyance unit 50 includes a document table 2, a sheet feeding guide plate 3, a bottom plate 4, a calling member 5, a sheet feeding member 6, a separation member 7, a conveyance roller 8, and a conveyance driven roller. 8a, registration sensor 9, intermediate conveyance roller 11, intermediate driven roller 11a, paper discharge roller 12, paper discharge lower driven roller 12a, paper discharge upper driven roller 12b, paper discharge sensor 13, switching claw 14, paper discharge tray 15, reverse roller 16, a reverse driven roller 16a, an intermediate tray 17, a reverse sensor 18, a first transport path R1, a second transport path R2, a third transport path R3, and a fourth transport path R4. A document 1 is stacked on the document table 2.

  The reading unit 80 can read the original by moving the exposure lamp 132 and the first mirror 131 in the horizontal direction in the drawing below the contact glass 111, while the original conveyed on the contact glass 110. When reading is performed, the exposure lamp 132 and the first mirror 131 are stopped below the contact glass 110 (10 reading position in the figure) and read. Reflected light from the document surface irradiated by the exposure lamp 132 is incident on the reading element 121 such as a CCD through the first mirror 131 and the lens 133 to form an image.

  As shown in FIG. 2, the main body 60 includes a main body control unit 41 that controls the entire apparatus. The main body control unit 41 receives a signal transmitted from the automatic document conveyance unit 50 via the communication unit 104. Receive. In addition, the main body control unit 41 performs drive control of the reading unit 80, display control in the operation unit 43, and the like based on the information indicated by the signals received and input in this manner, and the operation mode for the automatic document conveyance unit 50. Various control signals including a signal and a paper feed start signal are transmitted, and the ADF controller 29 is instructed to control the transport operation of the automatic document transport unit 50.

  The operation unit 43 includes various buttons such as a start button and a numeric keypad (not shown), an LCD display, and the like so that setting of each operation mode and operation start / stop instruction can be performed by a user operation. It is configured.

  The automatic document feeder 50 includes an ADF controller 29 that controls the operation of the automatic document feeder 50. The ADF controller 29 includes detection signals from the sensors 9, 13, 18, 71, 72, and the like, and motors. Status signals from 30 to 33, 35, 118, etc., and control signals (such as a paper feed start signal) transmitted via the communication means (serial communication line) 104 with the main body 60 are input. In addition, the ADF controller 29 transmits detection information from the sensors 9, 13, 18, 71, 72, and the like to the main body control unit 41 on the main body 60 side and based on a control signal transmitted from the main body control unit 41. Thus, the drive of each of the motors 30 to 33, 35, 118 is controlled. The RAM (not shown) of the main body control unit 41 stores the operation mode and the like input / set from the operation unit 43 of the main body 60, and updates the stored content every time the content is changed.

  The document 1 stacked with the first image surface facing upward on the document table 2 in a state where the automatic document transport unit 50 is lifted down (automatic transport mode) is started by the operation unit 43 of the image reading apparatus main body 60. When the button is pressed, the signals from the main body control unit 41 are supplied one by one from the top document in order onto the contact glass 110 of the reading unit 80 through the first transport path R1. The operation procedure will be described below.

  The leading edge of the document 1 is positioned by abutting against the paper feed guide plate 3.

  The bottom plate 4 is raised in the direction of arrow A by a SOL (not shown) in response to a paper feed start signal from the main body, and presses the document 1 against the calling member 5 from below. The pressurized document 1 is conveyed by a calling member 5 to a separation unit including a sheet feeding member 6 and a separation member 7 and separated one by one from the top.

  The raised bottom plate 4 is lowered after a certain time from the start of paper feeding or after the leading edge of the document is detected by a registration sensor 9 described later. By lowering, the pressure between the bottom plate 4 and the calling member 5 applied to the document 1 is released, and the time during which the second image surface of the document being conveyed is rubbed against the first image surface of the next document can be shortened. When the bottom plate 4 is lowered after a certain time from the start of feeding, it is desirable to set the time as short as possible.

  When the document 1 is only a single-sided image (first image surface), the bottom plate 4 does not have to be lowered because there is no second image surface. The user can set whether to perform single-sided reading or double-sided reading.

  The separated document 1 is conveyed to a first conveyance path R1 having a conveyance roller 8 and a conveyance driven roller 8a. The registration sensor 9 detects the leading edge of the document and matches the timing of passing the leading edge of the document to the reading unit 80 of the main body 60 and the start of image reading. If the leading edge of the document does not reach the registration sensor 9 after a certain period of time has elapsed after the document is fed, it is determined that a jam has occurred.

  In the case of reading only the first image surface (single-sided mode), after the image of the original 1 is read by the reading unit 80, the intermediate conveyance roller 11, the intermediate driven roller 11 a, the paper discharge roller 12, and the paper discharge follower are driven. The paper is discharged to a paper discharge tray 15 through a second feed path R2 having a roller 12a. The paper discharge sensor 13 is judged to be jammed when the leading edge of the document does not reach the paper discharge sensor 13 even after a certain time elapses or when the trailing edge of the document does not pass the paper discharge sensor 13 even after a certain time elapses. . The switching claw 14 is normally held at the position B.

  In the case of reading the first image plane and the second image plane (double-sided mode), after reading the first image plane, it is detected that the leading edge of the document has reached the paper discharge sensor 13 through the second feeding path R2, or The switching claw 14 is lowered to the position b by the SOL (not shown) at the timing from the detection by the registration sensor 9 and passes through the third feeding path R3 having the reverse roller 16 and the reverse driven roller 16a, and the intermediate tray 17 Transported up. If the document does not reach the reversal sensor 18 even after a predetermined time has elapsed, it is determined that a jam has occurred.

  The switching claw 14 is not shown after the document trailing edge has passed through the paper discharge sensor 13 and a predetermined time has elapsed (time until the document trailing edge passes through the paper discharge roller 12 and reaches the switching claw 14). When the SOL is released, the position B is restored. After the switching claw 14 returns, the reversing roller 16 reverses and the leading edge of the document enters the nip portion between the paper discharge roller 12 and the paper discharge driven roller 12b. At this time, the paper discharge roller 12 is stopped, and a so-called skew (original bending) abutting correction is performed. After completion of the abutting correction, the document 1 passes through the fourth transport path R4 and the first transport path R1, and the image information on the second image surface is read by the reading unit 80.

  When the second image surface is read and then discharged through the second feeding path R2 to the discharge tray 15 in this state, the second image surface is stacked downward, and the page order of the document is out of order. After the document 1 is transported onto the intermediate tray 17 through the second feed path R2 and the switching claw 14 is lowered to the position b and passed through the third feed path R3 so that the first image surface is stacked downward. The switching claw 14 returns to the position B, and is discharged onto the paper discharge tray 15 through the fourth transport path R4, the first transport path R1, and the second transport path R2.

  The feeding of the next original is started by a signal from the main body. However, if the bottom plate 4 that is lowered at this time is raised, it takes time to raise, so that the next original is fed so as not to reduce the productivity. The bottom plate 4 is raised in preparation for paper. During the document discharge operation, when the leading edge of the document passes through the fourth transport path R4 and the registration sensor 9 detects the leading edge of the document, the bottom plate 4 is raised.

  The bottom plate 4 may be raised from the time when the trailing edge of the document 1 passes through the calling member 5 until the start of feeding the next document. Set when.

  FIG. 3 is a perspective view when the automatic document feeder 50 of the present invention is opened.

  The automatic document feeder 50 is configured to be openable and closable with respect to the main body 60 by connecting members 153a and 153b such as hinge members. In the pressure plate mode, the automatic document feeder 50 is lifted up, and the sheet document (or book document) placed on the contact glass 110, 111 on the upper surface of the main body is pressed by the white member (pressure plate) on the lower surface of the automatic document feeder 50. Read. Further, a white document guide member 112 is attached to the automatic document feeder 50, and positioning guide members are attached to the main body 60 before and after the contact glass 110 and the contact glass 111.

  In FIG. 4, the example of attachment of the contact glass 110 attached to the main body 60 so that a movement is possible is shown.

  The contact glass 110 of the reading unit 80 is fixed to the fixing member 114a, and is configured to be movable with respect to the main body 60 in conjunction with the fixing member 114a. That is, the positioning pins 115a and 115b provided in the main body 60 are inserted into the long holes 113a and 113b formed in the fixing member 114a, and the shaft 117c of the rotary cam 117 provided in the main body 60 is formed in the fixing member 114a. The fixed member 114a is configured to move only in the sub-scanning direction (arrow direction in the figure) along the positioning pins 115a and 115b by the rotation of the rotating cam 117. ing.

  The fixing member 114 a is covered with a fixing member 114 fixed to the main body 60. Further, as shown in FIG. 5, the contact glass 110 is held by a sheet metal window frame forming a fixing member 114a.

  Further, as shown in FIG. 6, a rotating cam 117 for transmitting power to the fixing member 114a is installed below the fixing member 114a. Under the control of the main body control unit 41, drive transmission is made from the cam drive motor 118 via the timing belt 154 to the rotating cam 117, and the rotating cam 117 rotates about the shaft 117a. The rotational drive of the rotary cam 117 is driven from the drive transmission pin 117c to the fixed member 114 through the elongated hole 113c of the fixed member 114, and the fixed member 114 reciprocates in the sub-scanning direction. Further, a notch 117b is formed in the rotating cam 117, and the home position sensor 116 detects this notch 117b, thereby determining whether or not the contact glass 110 is in the home position. The home position of the contact glass 110 is set to the position shown in FIG.

  A document scooping guide 155 is provided downstream of the contact glass 110 with a step as shown in FIG. A flexible member 119 such as Mylar is provided on the upper surface of the document scooping guide 155, and one end of the flexible member 119 is in contact with the downstream end of the contact glass 110. In addition, as the flexible member 119, for example, a polyester film having a smaller coefficient of friction with a document than a coefficient of friction between another conveying member and the document, or the surface is so-called low friction treatment (Teflon coating or the like). The elastic member (rubber material) etc. which were made are used.

  The movement operation of the contact glass 110 is as shown in FIG.

  When the leading edge of the separated and conveyed document 1 is detected by the registration sensor 9, the main body control unit 41 starts to count the driving pulses of the conveying roller 8, and when the leading edge of the document reaches the document scooping guide 155, cam driving is performed. A contact glass movement signal is sent to the motor 118. The cam drive motor 118 rotates CW by the signal (step s201), and the contact glass 110 moves from the home position shown in FIG. 7 to the position shown in FIG. 9, and further moves from the position shown in FIG. 9 to the home position position. . When the home position sensor 116 detects the notch 117b (step s202), the main body control unit 41 stops the cam drive motor 118.

  The one reciprocating operation described above is performed at a preset time X (s) by one drive of the cam drive motor 118. For example, when the A4 landscape size is exposed in 1 second, when the A4 landscape document is exposed, the cam drive motor 118 is controlled to rotate 1/2 turn over about 1 second, so that the contact glass is exposed during the document exposure. 110 moves in the same direction as the document. By moving only in the document transport direction during document exposure, dirt on the contact glass 110 is unlikely to stay at the exposure position. Further, only the surface of the contact glass 110 that can be automatically cleaned can be set as the exposure position. In order to prepare for the next paper feeding operation after 1/2 rotation, the cam drive motor 118 is controlled to rotate 1/2 and return to the home position regardless of the preset rotation speed. When returning to the home position, it is preferable to rotationally drive the rotating cam 117 at a higher speed than when the rotating cam 117 is moved in the same direction as the original.

  In addition, since the above-mentioned cleaning member 120 is always in contact with the contact glass 110, the glass cleaning is automatically performed by moving the contact glass 110. Further, the flexible member 119 provided on the glass document scooping guide 155 is elastically deformed and stored when the contact glass 110 moves from the position of FIG. 7 to FIG. 9, thereby preventing the movement of the contact glass 110. There is nothing.

  FIG. 10 shows the document exposure operation in this embodiment.

  As described above, the document fed and separated from the document table 2 in the automatic transport mode is reversed along the first transport path R1 by the transport roller 8 and the transport driven roller 8a which are rotationally driven by the transport motor 31. It is conveyed toward the contact glass 110.

  Here, when the leading edge of the document is detected by the registration sensor 9 and the registration is stopped (step s101), the main body control unit 41 determines whether or not the contact glass 110 is at the home position from the detection information of the home position sensor 116. If it is in the home position, the document is conveyed to the reading position (exposure position) (step s103).

  Next, the main body control unit 41 starts the sheet-through type exposure process by the reading unit 80 at the timing when the leading end of the document reaches the exposure position (step s104) from the pulse count value of the transport roller 8 as described above (step s104). Step s105). As described above, the document transported to the exposure position by the transport roller 8 and the transport driven roller 8a is guided by the document guide member 112, passes through the contact glass 111 at a constant speed, and has the lens 133, the mirror 132, and the CCD 121. , Etc. are exposed by an imaging element.

  The leading edge of the document is picked up by a document scooping guide 155 and further conveyed. Here, when the main body control unit 41 determines that the leading edge of the document has reached the scale (the document scooping guide 155) from the pulse count value of the conveying roller 8 described above (step s106), the main body control unit 41 starts the movement processing of the contact glass 110. (Step s107). As described above, the rotation of the rotary cam 117 causes the fixing member 114 to reciprocate in the sub-scanning direction, and the contact glass 110 held by the fixing member 114 also reciprocates in the same direction (sub-scanning direction) as the document conveyance direction. To do. It is desirable that the moving speed of the contact glass 110 is set so that the contact glass 110 continues to move in the same direction until the read original is completely exposed.

  Next, the main body control unit 41 ends the exposure processing by the reading unit 80 (step s109) at the timing when the trailing edge of the document reaches the exposure position from the pulse count value of the conveying roller 8 described above (step s109). Here, when the one driving operation of the rotating cam 117 is set to be the same as the reading operation of one original, the returning operation of the contact glass 110 by the driving of the rotating cam 117 further continues, and the pulse count of the conveying roller 8 described above is continued. From the value, the home position sensor 116 detects the notch 117b at the timing when the trailing edge of the document reaches the scale.

  Thereafter, the document is sandwiched and conveyed by the intermediate conveyance roller 11, the intermediate driven roller 11a, the paper discharge roller 12, and the paper discharge lower driven roller 12a, and is discharged onto the paper discharge tray 15 from the second conveyance path R2 (step). s110). Note that the contact glass 110 returns to the position before exposure and stands by for exposure of the next document. After determining that the contact glass 110 has returned to the home position as described above, the main body control unit 41 permits the next document to be conveyed to the exposure position.

  In the present embodiment, since the contact glass 110 moves in the same direction as the document conveyance direction for each document reading operation, exposure processing is always performed at a different position on the contact glass 110, and dust adheres to the contact glass 110. Even if there is dirt or dirt, it is possible to suppress deterioration in image quality due to the occurrence of so-called black streaks.

[Second Embodiment]
FIG. 11 shows a part of the circuit configuration of the main body control unit of the image forming apparatus according to the present invention, and FIG. 12 shows the configuration of the stain detection circuit. Since the overall configuration of the apparatus is substantially the same as that of the first embodiment, FIGS. 1 to 7 and FIG. 9 are used, and the same reference numerals are given to the same configurations and description thereof is omitted.

  The image data read by the CCD (reading element) 121 is converted into an analog signal. Further, as shown in FIG. 11, the analog signal is amplified by the image amplifying circuit 122, and the output signal is analog / The digital conversion (A / D conversion) circuit 123 converts it into a multi-value digital image signal (DA) and sends it to the dirt detection circuit 124.

  As shown in FIG. 12, the dirt detection circuit 124 includes a binarization processing unit 126 that binarizes the image data DA from the A / D conversion circuit 123 with the threshold data D (th), and the binarization processing. The data delay unit 127 that delays the image data DA (n) from the unit 126 to the previous one to make DA (n−1) is compared with the image data DA (n) and DA (n−1). And a dirt detector 128 for detecting dirt on the contact glass 110. The dirt detection circuit 124 compares the digital image signal DA (n) from the A / D conversion circuit 123 with the previous digital image signal DA (n−1) read prior to the digital image signal DA (n). From this difference, it is possible to detect the contamination of the contact glass 110 and determine whether the detected contamination is the contamination of the opposing surface (document guide 112) or the contact glass 110.

  Here, the binarization of the image data (DA) is caused by the sensitivity variation of the reading element 121, the unevenness of the light amount of the exposure lamp 131, or the variation caused by the light amount distribution error of the contact glass 110 or the lens 133. This is to prevent erroneous detection of the difference. The image data (DA) is normally output in 8 bits and 256 gradations, and the threshold data D (th) is a value indicating from which level the image data (DA) is determined to be black.

  Since the document guide 112 is in contact with the back side of the image surface (reading surface) of the document, an image abnormality such as a black streak is unlikely to occur unless the document has a high light transmittance such as thin paper, but the contact glass 110 is soiled. In such a case, it is always important to determine which stain it is. Further, even if the stain on the contact glass 110 is read by the CCD 121, the image mainly reads the white surface of the document guide 112 to determine whether the contact glass 110 is stained or the document guide 112 is stained. Judgment requires the method described below.

  FIG. 13 shows a contact glass moving operation for detecting dirt, and FIG. 14 shows details of the dirt detecting process.

  In order to detect the contamination of the contact glass 110 by the above-described contamination detection circuit 124, as shown in FIG. 13, the main body control unit 41 detects that the automatic document conveyance unit 50 is lifted down based on detection information from a lift-up sensor (not shown). It is then determined whether or not it is in a closed state (step s301), and if the automatic document feeder 50 is in a closed state, a stain detection process is started (step s302).

  Here, the main body control unit 41 performs a fixed reading operation by the reading unit 80 while moving the contact glass 110 from the home position by driving the rotating cam 117 (step s303), and reciprocating the contact glass 110 by one drive. When the operation ends (step s304), the dirt detection operation ends.

  As shown in FIG. 14, the stain detection process started in step s302 is first performed by the above-described stain detection circuit 124, which reads the digital image signal DA (n) from the A / D conversion circuit 123 prior to this. The previous digital image signal DA (n−1) is compared (step s401), and if the two match, the process ends (step s402). On the other hand, if the data are different, further image noise detection processing is performed (step s403), and it is determined that the contact glass 110 is dirty and dust or dirt of a predetermined size or more is attached. The main body control unit 41 sends a reading prohibition signal to the reading unit 80 to prohibit the reading operation of the original and display a warning by the operation unit 43 (step s404).

  Note that, as a criterion for determining whether or not to prohibit the reading operation, the level of contamination can be arbitrarily set according to the magnitude of the detected noise. However, frequent prohibition of the reading operation impairs the operability of the user. A value of about 6 pixels may be used as a criterion.

  Further, as shown in FIG. 15, the contact glass moving operation started in step s303 is performed by CW driving the cam drive motor 118 under the control of the main body control unit 41 and by rotating the rotary cam 117 as described above. This is an operation (corresponding to FIG. 8) in which the glass 110 is reciprocated from the home position and the cam drive motor 118 is stopped after returning to the home position.

  In the present embodiment, the reading operation is performed while moving the contact glass 110 to detect the dirt above the reference and whether the dirt is on the white plate (pressure plate) of the automatic document feeder 50 or the contact glass 110. Since the determination is made, it is possible to warn the user and prompt the user to clean the dirt and dust on the contact glass 110 which are easier to clean than the white plate and adhere to the contact glass 110.

  In the present embodiment, the contact glass 110 is moved in the sub-scanning direction to detect dirt, but it may be moved in the main scanning direction. Specifically, as shown in FIG. 16, the above-mentioned fixing member 114 is moved with respect to the main body 60 in the main scanning direction (see FIG. The fixing member 114 may be slidably mounted in the main scanning direction and fixed to the main body side by a spring 152, and the other side may be sucked by a solenoid 151. By attracting / releasing this solenoid 151, the contact glass 110 can be reciprocated in the main scanning direction. At the time of the above-described stain detection, the document and the contact glass 110 do not come into contact with each other, so the stain detection in the main scanning direction is effective.

[Third Embodiment]
17 to 20 show the installation state of the contact glass of the image reading apparatus according to the present invention. In addition, since the structure of the whole apparatus is as substantially the same as 1st Embodiment, while using FIGS. 1-6, the same code | symbol is provided to the same structure and description is abbreviate | omitted.

  In this embodiment, in addition to the apparatus of the first embodiment, the contact glass 110 can be moved in the left direction in the figure from the home position. In addition, upstream of the contact glass 110, a cleaning member 120 is provided across the width direction on the fixing member 114 side so as to be in contact with the upper surface of the contact glass 110. The cleaning member 120 is obtained by impregnating an elastic member (rubber material) or cloth with a water repellent coating treatment agent or a low friction treatment agent in order to prevent dust or the like from adhering to the upper surface of the contact glass 110.

  In the present embodiment, when the contact glass 110 moves in the right direction in the drawing, the invention of the first embodiment can be performed, and when the contact glass 110 moves in the left direction in the drawing, the reading position of the contact glass 110 is cleaned. It becomes possible to do. As a driving method, as shown in FIG. 21, the radius of the rotary cam 117 of the first embodiment is approximately doubled so that the drive transmission pin (shaft) 117c 'and the notch 117b' are positioned diagonally. To. By doing so, the contact glass 110 is located at the home position in the state shown in the figure. Here, when the rotating cam 117 'rotates in the CW direction from the home position, the contact glass 110 moves in the right direction described above, and when it rotates 1/4 (90 °), it reverses and returns to the home position. On the other hand, when the rotating cam 117 ′ rotates in the CCW direction from the home position, the contact glass 110 moves in the left direction as described above, and when rotated by ¼ (90 °), the contact glass 110 returns to the home position. As described above, the contact glass 110 can reciprocate in both the left and right directions.

  As shown in FIG. 17, a reading position (exposure position) is provided at a substantially central portion of the contact glass 110, and the cleaning member 120 is in contact with one side of the upper surface of the contact glass 110. For cleaning, the contact glass 110 performs the above-described reciprocating operation in the left direction after completion of a predetermined operation mode or at an arbitrary cycle (for example, every time a predetermined number of documents are read) under the control of the main body control unit 41. By this reciprocation, the cleaning member 120 (infiltrated with the water repellent or low friction treatment agent as described above) 120 moves relative to the contact glass 110, and the glass surface is subjected to water repellent or low friction. Apply processing.

  Further, with respect to the movement in the right direction described above, the reciprocating motion is repeated for each original document in substantially the same manner as in the first embodiment.

[Fourth Embodiment]
FIG. 22 shows a schematic configuration of an image reading apparatus using the contact type sensor according to the present invention.

The image forming apparatus 300 is a sheet-through type, and a pair of support members 146a, between a contact-type sensor (CIS) 142 for image reading and a pressing white roller 141 that presses a document against the contact-type sensor 142 , A transparent sheet (for example, composed of PET or the like) 145 spanned on 146b is sandwiched, and the image surface of the original is read through the transparent sheet 145.

  The transparent sheet 145 wound around the feeding roller 143 is sequentially fed out at an arbitrary cycle (for example, every time the number of originals to be read reaches a predetermined value) and wound around the winding roller 144. By appropriately setting the period, it is possible to always read an image through a new transparent sheet 145 (with the exposure position relatively moved). Alternatively, a reading operation is performed while winding up the transparent sheet 145 for the above-described dirt detection, and only when a dirt of a predetermined level or higher is detected, a new transparent sheet 145 after winding is used and the predetermined level or lower is used. In some cases, the feeding roller 143 may be driven to rewind the transparent sheet 145 so that it can be used again.

  In the present embodiment, since the transparent sheet 145 is wound up, it is possible to improve the image quality by preventing the occurrence of abnormalities such as black streaks without particularly providing a cleaning member.

  In each of the above-described embodiments, the image reading apparatus having both the document fixing / optical activation and the document moving / optical fixing method has been described. However, the same effect can be obtained in an image reading apparatus having only the document moving / optical fixing method. Of course, it can be obtained.

  The fixed member 114, the rotating cam 117, the home position sensor 116, etc. constitute moving means, the main body control unit 41, etc. constitute control means, and the document scooping guide 155, the flexible member 119, etc. serve as guiding means. The stain detection circuit 124 and the like constitute stain detection means, the operation unit 43 and the like constitute display means, the sheet feeding roller 143 and the like constitute sheet feeding means, and the sheet and the take-up roller 144 and the like are sheet. A winding means is configured.

  As described above, according to the present invention, black streaks resulting from dust adhesion are prevented by preventing dust from adhering and staying on the contact glass (original table) with the digital type document moving / optical system fixing method. Therefore, it is possible to provide an image reading apparatus that can obtain good read image data.

1 is an overall configuration diagram of an image reading apparatus according to a first embodiment of the present invention. FIG. 2 is a diagram illustrating a configuration of a control unit of the image reading apparatus according to the first embodiment of the present invention. 1 is a perspective view of an image reading apparatus (when lifted up) according to a first embodiment of the present invention. It is a figure which shows attachment of the contact glass which concerns on the 1st Embodiment of this invention. It is a perspective view which shows the fixing member to which the contact glass which concerns on the 1st Embodiment of this invention was attached. It is a figure which shows the drive part for moving the contact glass which concerns on the 1st Embodiment of this invention. It is a figure which shows the structure (home position) of the contact glass vicinity which concerns on the 1st Embodiment of this invention. It is a flowchart which shows the movement operation | movement of the contact glass which concerns on the 1st Embodiment of this invention. It is a figure which shows the structure of the contact glass vicinity which concerns on the 1st Embodiment of this invention. 3 is a flowchart showing an exposure operation of the image reading apparatus according to the first embodiment of the present invention. It is a figure which shows the function structure (contamination detection) of the control part of the image reading apparatus which concerns on the 2nd Embodiment of this invention. It is a figure which shows the function structure of the dirt detection circuit of FIG. 10 is a flowchart showing a contact glass movement / dirt detection operation of the image reading apparatus according to the second embodiment of the present invention. 6 is a flowchart illustrating a dirt detection operation of the image reading apparatus according to the second embodiment of the present invention. 6 is a flowchart showing a contact glass moving operation of the image reading apparatus according to the second embodiment of the present invention. It is a figure which shows attachment of the contact glass which concerns on other embodiment of this invention. It is a figure which shows the structure of the contact glass vicinity which concerns on the 3rd Embodiment of this invention. It is a figure which shows the structure (rotating cam 1/4 rotation) vicinity of the contact glass which concerns on the 3rd Embodiment of this invention. It is a figure which shows the structure (rotating cam 2/4 rotation) vicinity of the contact glass which concerns on the 3rd Embodiment of this invention. It is a figure which shows the structure (rotating cam 3/4 rotation) of the contact glass vicinity which concerns on the 3rd Embodiment of this invention. It is a figure which shows the drive part for moving the contact glass which concerns on the 3rd Embodiment of this invention. It is a figure which shows the structure of the reading part of the image reading apparatus which concerns on the 4th Embodiment of this invention.

Explanation of symbols

50 Automatic document feeder (ADF)
110, 111 Contact glass 112 Document guide member 113a-113c Long hole 114 Fixing member 115a, 115b Positioning pin 116 Home position sensor 117, 117 'Rotating cam 117a Rotating shaft 117b, 117b' Notch 117c, 117c 'Drive transmission pin (shaft )
118 Cam drive motor 119 Flexible member 155 Document scoop guide

Claims (2)

The reading unit includes a contact-type sensor for reading an image and a document while pressing the document against the contact-type sensor and a white roller as a reference roller. The reading unit is fixed and the image is read while the document is transported. An image reading apparatus for performing
A pair of support members disposed on the upstream side and the downstream side in the conveyance direction of the document with the contact sensor interposed therebetween;
Sandwiched between the pressing roller and the contact-type sensor, with bridged to said pair of support members so as to form a flat shape toward the downstream side from the document conveying direction upstream side includes the contact-type sensor sub A transparent sheet for placing a document moving in the scanning direction ;
A sheet feeding means provided on a side where the contact sensor is disposed with respect to a position where the document is pressed against the contact sensor ;
A sheet take-up unit that is provided on a side where the contact type sensor is disposed with respect to a position where the document is pressed against the contact type sensor, and winds up the fed transparent sheet;
Control means for winding up the transparent sheet fed by the sheet feeding means at a predetermined cycle by the sheet winding means,
An image reading apparatus that reads an image by relatively moving a contact-type sensor and a reading position of a transparent sheet in the sub-scanning direction . The image reading apparatus according to claim 1, further comprising: an image reading unit that reads an image of a document; and an image forming unit that forms an image of the document read by the image reading unit on a predetermined sheet. An image forming apparatus using the apparatus.

Images