JP4908292B2 - Document reading apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a document reading apparatus and an image forming apparatus, and in particular, a document reading unit that reads a conveyed document, and a distance between the document and the document reading unit that is provided facing the document reading unit and guides the document. And an image reading apparatus and an image forming apparatus.

The image reading apparatus includes a reduction optical system type using an image sensor such as a CCD, and a close contact type in which a line-shaped light source and an image sensor are arranged in parallel in the width direction (main scanning direction) of the document. There is a double optical system type. In any type of image sensor, in order to accurately read an image of a document, the document can be stably run at a predetermined constant speed at the image reading position, and the document can be run close to the reading surface. is important. In particular, the contact image sensor of the equal-magnification optical system has a very shallow depth of focus as compared with that of the reduction optical system.

  As described above, in the image reading apparatus, it is necessary to maintain an appropriate distance between the image sensor and the document. Examples of such a document reading apparatus include the following. In Patent Document 1, the operator controls the separation unit and the separation unit so that the separation unit moves the document pressing and conveying unit in the direction separating from the conveyance path in response to pressing of a specific input unit from the operation unit. An image reading apparatus including a control unit is described.

  Japanese Patent Application Laid-Open No. 2005-228561 discloses an image forming apparatus including an automatic document feeder having a first surface reading unit that reads a front surface of a document image and a second surface reading unit that reads a back surface of the document image. An image reading apparatus having a conveyance gap adjustment driving unit capable of adjusting a conveyance gap of the unit is described.

  Japanese Patent Application Laid-Open No. 2004-228561 describes an image reading apparatus that includes a scooping guide that guides the leading end of the reading unit path to the paper discharge path and forms a reading path at a position spaced from the surface of the platen.

  Further, in the document image reading device, there has conventionally been a problem that vertical streaks occur in the read document due to accumulation of dust such as paper dust of the document at the reading position. A method is used in which a document is strongly pressed against a reading surface and dust is removed by the document itself (self-cleaning).

  On the other hand, there are adhesive-type dust that cannot be removed by self-cleaning, such as glue that adheres to the document, as a countermeasure. The method is adopted.

  There are the following image reading apparatuses having such a coating. In Patent Document 4, a non-coating region and a coating region for preventing dirt adhesion are arranged close to each other at a position where the leading edge of a sheet to be read comes into contact with the transparent glass, and the dirt on the reading object is read. An image reading device is described which removes the uncoated area in front of.

Further, in Patent Document 5, as an example of applying an anti-smudge coating to an image reading apparatus, in a reading apparatus that reads white reference data of a background member and performs shading correction, the background member is covered with a photocatalyst that decomposes the dirt. An image reading apparatus that irradiates a white reference member according to the degree is described.
Japanese Patent No. 3472676 JP 2004-274278 A Japanese Patent Laid-Open No. 10-171182 JP 2005-269210 A JP 2004-282166 A

  However, the surface of the coating described above is gradually removed rather than the conveyance of the original, and as described above, especially when the original is strongly pressed against the reading surface in order to remove paper dust, the life of the coating is significantly reduced. There was a problem.

  According to the present invention, it is possible to prevent the coating of the reading surface from being worn in a document reading apparatus having a configuration for pressing the document against the reading surface in order to remove paper dust. An object of the present invention is to provide an image reading apparatus and an image forming apparatus capable of preventing the occurrence of vertical stripes.

The invention of claim 1
A document reading means for reading a document to be conveyed;
The document reading means has a first reading unit for reading the front side of the document and a second reading unit for reading the back side of the document,
A guide means provided opposite to the second reading unit , for guiding the document and setting a distance between the document and the second reading unit;
In an image reading apparatus comprising:
Reading surface of the second reading portion, the coating member having the dirt disassembly function, or can be varied Rutotomoni with a coating member having a hydrophilic, the distance between the guide means and the second reading unit It has a distance change mechanism ,
The document reading device includes a duplex mode for reading the front and back surfaces of a document, and a single-side mode for reading only the surface of a document,
The distance changing mechanism is
In the double-side mode, the distance between the guide means and the second reading unit is maintained at a distance suitable for document reading, and in the single-side mode, the distance between the guide means and the second reading unit is set to a document. While extending beyond the distance suitable for reading,
In the single-sided mode, the distance between the guide means and the second reading unit is maintained at a distance suitable for the document reading once per predetermined number of document reading operations.
An original reading apparatus characterized by the above.

The invention of claim 2 is the document reading apparatus according to claim 1, wherein the distance changing mechanism is characterized Rukoto with the previous SL second reading unit solenoid to extend the distance between said guide means.

According to a third aspect of the present invention, the distance changing mechanism includes a motor that increases a distance between the document reading unit and the guide unit.

A fourth aspect of the present invention, in the document reading apparatus according to claim 3, wherein the motor is characterized that you have also serves as a motor for driving the conveying roller.

According to a fifth aspect of the present invention, in the document reading device according to any one of the first to fourth aspects, the distance changing mechanism increases a distance between the second reading unit and the guide unit when the document is jammed. It is characterized by that.

According to a sixth aspect of the invention, the document reading apparatus according to any one of claims 1 to 5, wherein the guide means is characterized Oh Rukoto a roller.

According to a seventh aspect of the present invention, in the document reading device according to the sixth aspect , a bearing is disposed at the roller end portion, and a part of the outer peripheral surface of the bearing is brought into contact with the document reading means reading surface. coercive Chi the length of the roller and the document reading hand stage an appropriate distance for reading the document,
When the distance between the roller and the document reading unit is increased, only the roller moves while the bearing is fixed .

The invention according to claim 8 is the document reading device according to claim 6 or 7 , wherein the rotation of the roller is stopped when the distance between the roller and the document reading means is increased. .

A ninth aspect of the present invention is an image forming apparatus comprising the original reading apparatus according to any one of the first to eighth aspects.

  According to the document reading apparatus of the present invention, since the distance between the guide unit and the document reading unit is changed by the distance changing mechanism, the coating on the reading surface can be prevented from being worn, and the two kinds of the above can be different over a long period of time. There is an effect that it is possible to prevent the occurrence of vertical stripes due to the dust of the nature.

  Embodiments as the best mode for carrying out the present invention will be described below with reference to the drawings.

  In the present embodiment, the image reading apparatus is applied to a read original processing apparatus (hereinafter referred to as ADF) in which an original to be read is conveyed to a fixed reading unit and is read while being conveyed at a predetermined speed. The basic configuration, operation, and operation will be described below. FIG. 1 is a schematic sectional view showing a configuration of the image reading apparatus, and FIG. 2 is a block diagram showing an overall control system of the image reading apparatus.

  The document reading apparatus is disposed on the upper part of an image forming apparatus such as a copying apparatus or an MFP. A document setting unit A for setting a document bundle to be read, and separating and feeding each document from the set document bundle. Separating and feeding unit B that performs primary and abutting alignment of the fed document, and registration unit C that extracts and conveys the aligned document, turns the conveyed document, and reads the document surface A turn part D that conveys toward the (downward); a first reading and conveying part E that reads the surface image of the document from below the contact glass; a second reading and conveying part F that reads the back image of the document after reading; A paper discharge unit G that discharges a document that has been read from the front and back sides to the outside of the apparatus, and a stack unit H that stacks and holds the document after reading is provided. The document reading apparatus also includes a pickup motor 101, a paper feed motor 102, a reading motor 103, a paper discharge motor 104, a bottom plate raising motor 105, which are driving units for driving these conveying operations, and ADF control for controlling a series of operations. Part 100 is provided.

  The document table 2 includes a movable document table 3 on which a document 1 to be read is set. The document 1 is set on the document table 2 with the document surface facing upward. The document table 2 is provided with a side guide (not shown), and is positioned in a direction orthogonal to the width direction of the document 1. The set document 1 is detected by the set filler 4 and the set sensor 5 and transmitted to the main body control unit 111 by the I / F 107.

  Further, document length detection sensors 30 and 31 (a reflection type sensor or an actuator type sensor capable of detecting even one document) are arranged on the document table 2, and the document length detection sensor 30. , 31 determine the length of the document in the conveyance direction. At this time, the document length detection sensors 30 and 31 are arranged so as to be able to determine at least whether the document size is vertical or horizontal.

  The movable document table 3 can be moved up and down in the directions of arrows a and b by a bottom plate raising motor 105. When it is detected by the set filler 4 and the set sensor 5 that the original is set on the movable original table 3, the movable original table is rotated so that the bottom plate raising motor 105 is rotated forward so that the uppermost surface of the original bundle contacts the pickup roller 7. Raise 3

  The pickup roller 7 is operated in the directions of arrows c and d by a pickup mechanism 101 by a pickup motor 101, and the movable document table 3 is raised and pushed by the upper surface of the document on the movable document table 3 to rise in the c direction, and the table elevation detection sensor 8. The upper limit can be detected.

  When the print key of the main body operation unit 108 is pressed and an original document feed signal is transmitted from the main body control unit 111 to the ADF control unit 100 via the I / F 107, the pickup roller 7 rotates by the forward rotation of the paper feed motor 102. Is rotated to pick up several (ideally one) originals on the original table 2. The rotation direction is a direction in which the uppermost document is conveyed to the sheet feeding port.

  The paper feed belt 9 is driven in the paper feed direction by the normal rotation of the paper feed motor 102, and the reverse roller 10 is driven to rotate in the reverse direction to the paper feed by the normal rotation of the paper 102 to separate the uppermost document from the document under it. Thus, only the uppermost document can be fed. In other words, the reverse roller 10 is in contact with the paper feed belt 9 at a predetermined pressure and is in direct contact with the paper feed belt 9 or in a state where it is in contact with the original through one sheet, and is counteracted by the rotation of the paper feed belt 9. The rotating force is set to be lower than the torque of the torque limiter when the two or more originals enter between the paper feeding belt 9 and the reverse roller 10 in a clockwise direction. Rotate in the clockwise direction, which is the driving direction, and push back excess originals, thereby preventing double feeding.

  The original separated by the action of the paper feeding belt 9 and the reverse roller 10 is further fed by the paper feeding belt 9, and the leading edge is detected by the abutting sensor 11 and further abuts against the pull-out roller 12 stopped. Then, the sheet feeding motor 102 is stopped in a state where it is fed by a predetermined distance from the detection of the abutting sensor 11 and is pressed against the pull-out roller 12 with a predetermined amount of deflection. By doing so, the driving of the paper feed belt 9 is stopped. At this time, by rotating the pickup motor 101, the pickup roller is retracted from the upper surface of the document and the document is fed only by the conveying force of the paper feed belt, whereby the leading edge of the document enters the nip of the pair of upper and lower rollers of the pull-out roller 12, Tip alignment (skew correction) is performed.

  The pull-out roller 12 has the skew correction function and conveys the skew-corrected document after separation to the intermediate roller 14 and is driven by the reverse rotation of the paper feed motor 102. Note that when the paper feed motor 102 rotates in reverse, the pull-out roller 12 and the intermediate roller 14 are driven, but the pickup roller 7 and the paper feed belt 9 are not driven.

  A plurality of document width sensors 13 are arranged in the depth direction and detect the size in the width direction perpendicular to the transport direction of the document transported by the pull-out roller 12. Further, 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 abutment sensor 11.

  When the document is transported from the resist section C to the turn section D by driving the pull-out roller 12 and the intermediate roller 14, the transport speed at the resist section C is set to be higher than the transport speed at the first reading transport section E. Thus, the processing time for sending the document to the reading unit is shortened.

  When the leading edge of the document is detected by the reading inlet sensor 15, before the leading edge of the document enters the nip of the upper and lower roller pairs of the reading inlet roller 16, deceleration is started to make the document conveying speed the same as the reading conveying speed. At the same time, the reading motor 103 is driven to rotate forward to drive the reading inlet roller 16, the reading outlet roller 23, and the CIS outlet roller 27. When the registration sensor 17 detects the leading edge of the document, the document sensor decelerates over a predetermined conveyance distance, temporarily stops before the reading position 20 where the first reading unit (not shown) is arranged, and A registration stop signal is transmitted via the I / F 107. Subsequently, when a reading start signal is received from the main body control unit 111, 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 on the first surface is sent to the main body control unit 111 after the first reading unit Sent until the edge is removed.

  In the case of reading a single-sided document, the document that has passed through the first reading and conveying unit E is conveyed to the paper discharge unit G through the second reading unit 25. At this time, when the leading edge of the original is detected by the paper discharge sensor 24, the paper discharge motor 104 is driven to rotate forward to rotate the paper discharge roller 28 counterclockwise. In addition, the discharge motor pulse count from the detection of the leading edge of the document by the discharge sensor 24 reduces the discharge motor drive speed immediately before the trailing edge of the document comes out of the nip of the pair of upper and lower rollers of the discharge roller 28 to discharge the document. Control is performed so that the document discharged onto the tray 29 does not jump out.

  In the case of double-sided original reading, a second reading constituted by a CCD line sensor is performed at a timing when the leading edge of the original reaches the second reading unit 25 by pulse count of the reading motor after the discharge sensor 24 detects the leading edge of the original. A gate signal indicating an effective image area in the sub-scanning direction is transmitted from the ADF control unit 100 to the unit 25 until the trailing edge of the original passes through the reading unit. The surface of the second reading unit 25 is subjected to a coating process and a coating member is disposed in order to prevent vertical streaks due to transfer of glue on the original onto the reading line.

  This coating member is formed by applying a coating material having a dirt decomposition function or a hydrophilic coating material to the reading surface of the second reading unit 25. These coating materials can use a well-known thing.

  Next, the second reading unit 25 will be described. FIG. 3 is a block diagram showing a reading control system of the image reading apparatus. As shown in FIG. 3, the second reading unit 25 includes a light source unit 200 that illuminates the back surface of the document 1 and a CCD line in which a sensor chip 201 that detects reflected light from the document 1 and outputs an electrical signal is arranged. And a sensor. A signal detected by the sensor chip 201 is digitized by an A / D converter 203 through a gate 202, and the digitized signal is passed through an image processing unit 204, a frame memory 205, an output control unit 206, and an IF circuit 207. Then, it is sent to the main body control unit 111 as an image signal. From the ADF control unit 100, a lighting signal is supplied to the light source unit 200, a timing signal is supplied to the output control unit 206, and power is supplied to the second reading unit 25.

The second reading roller 26 is a guide unit that guides the document and sets the distance between the document and the document reading unit. The second reading roller 26 suppresses the floating of the document in the second reading unit 25, and simultaneously outputs the shading data in the second reading unit. It also serves as a reference white part for acquisition. In this example, the second reading roller 26 is arranged as a guide means at a portion facing the second reading section 25, but a plate-like guide member 126 as shown in FIG. 4 is arranged as a guide means instead of a roller. be able to.

  FIGS. 5A and 5B are views showing a roller as a guide means. FIG. 5A is a schematic cross-sectional view when reading a document, and FIG. 5B is a schematic cross-sectional view when transferring a document. As shown in FIG. 5, the second reading roller 26 is configured to be movable in a direction away from the second reading unit 25, and when reading the original document 1, as shown in FIG. 2. The scanning unit 25 is placed at a reading position that maintains a predetermined position from the surface, and is conveyed at an appropriate position for reading a document. On the other hand, when the document 1 is transported without being read, as shown in FIG. 5B, the document 1 can be placed at a transport position away from the surface of the second reading unit 25.

  In the state where the second reading roller 26 is set to the reading position, the document 1 is conveyed while being pressed against the reading position. Therefore, dust such as paper dust is removed from the reading unit by the document itself by the self-cleaning effect described above. Therefore, it is possible to prevent the problem of vertical stripes due to these.

  On the other hand, when passing a single-sided document, the second reading unit 25 does not perform reading, but only the document 1 passes between the second reading unit 25 and the second reading roller 26. Therefore, FIG. ), The second reading roller 26 is separated from the surface of the second reading unit 25. Thereby, unnecessary coating deterioration of the second reading unit 25 can be prevented.

  Next, a distance changing mechanism that changes the distance from the second reading unit 25 by moving the second reading roller 26 will be described. FIG. 6 is a schematic side view showing the configuration of the distance changing mechanism. In this example, a lever 303 is connected to the shaft of the second reading roller 26, and the second reading roller 26 is usually disposed at a transport position away from the second reading unit 25 by the action of the tension spring 302. The When the solenoid 301 is energized and turned on, the solenoid 301 pulls the lever 303, the lever 303 rotates around the fulcrum, and the second reading roller 26 keeps a proper distance from the surface of the second reading unit 25. Move to.

  The distance changing mechanism can use a motor in addition to a solenoid. FIG. 7 is a schematic side view showing a configuration of a distance changing mechanism according to another example. In this example, the roller movement motor 304 is driven to rotate the lever 307 via the pulley 305 and the gear 306. In this example, the roller moving motor 304 is rotationally driven to move the second reading roller 26 to the transport position and the reading position. According to this example, since the lever 307 is driven by the forward / reverse motion of the motor, it can be driven more slowly than a device using a solenoid, so that noise and vibration can be prevented. .

  Further, this motor can be used not only to move the second reading roller 26 but also to drive other transport rollers via a gear. FIG. 8 is a schematic side view showing a configuration of a distance changing mechanism according to another example. In this example, the motor 308 rotationally drives the gear 310 and the gear 311 via the pulley 309. The gear 310 drives the lever 312 to move the second reading roller 26. On the other hand, a belt 313 is wound around the gear 311, and the conveyance roller 314 is rotationally driven by the belt 313. When the conveyance roller 314 is rotated in one direction, a one-way clutch may be arranged so that the gear 311 can rotate only in one direction even when the motor 308 rotates in the forward and reverse directions. According to this example, since the second reading unit 25 and the conveyance roller 314 can be driven by one motor 308, the number of motors can be reduced, and the cost can be reduced and the weight of the machine can be reduced. .

  Next, the operation of the document reading apparatus according to this example will be described. FIG. 9 is a flowchart showing a control state of the distance changing mechanism using the solenoid. When the user selects the single-sided mode / double-sided mode, the solenoid 301 operates in accordance with the selection, and a predetermined process is performed. That is, when the single-side mode is selected by the user (ST11), the solenoid 301 is turned off, and the second reading roller 26 is disposed at a transport position away from the second reading unit 25 (ST12). In this state, the surface of the document 1 is read by the first reading unit (ST14), and passes between the second reading unit 25 and the second reading roller 26 at the transport position. At this time, the document 1 does not rub the second reading unit 25 and does not wear the coating member of the second reading unit 25.

  On the other hand, when the duplex reading mode is selected (ST11), the solenoid 301 is turned on, the second reading roller 26 is placed at the document reading position, and the document 1 is pressed against the surface of the second reading unit 25 (ST15). Then, the front surface of the document 1 is read by the first reading unit (ST16), and then the back surface of the document 1 is read by the second reading unit 25 (ST18). When all the originals 1 are read, the solenoid 301 is turned off, and the second reading roller 26 is disposed on the conveyance 1 (ST19). These processes are performed for all the originals, and the original reading process is completed.

  As described above, the document 1 is pressed against the second reading unit 25 by the second reading roller 26 at the time of double-sided scanning to remove dirt such as paper dust on the surface of the reading unit, and is not pressed at the time of single-sided scanning. Although the operation for preventing the deterioration has been described, if only the single-sided reading operation is continuously performed, a large amount of paper dust accumulates on the surface of the second reading unit 25. If the double-sided reading operation is performed in this state, the paper dust may not be completely removed by one transport of the original 1. In order to prevent such a problem, for example, only the first sheet of the reading process is pressed against the second reading unit 25 even during single-sided reading.

FIG. 10 is a flowchart showing control for pressing the first original 1 against the second reading unit during single-sided reading. In this example, the solenoid 301 is initially turned on (ST21), and when the user selects the single-sided reading mode (ST22), the front side of the first sheet is read (ST23), and the solenoid is further turned on. The original 1 is allowed to pass while the second reading roller 26 is kept at the reading position in the ON state. Next, the solenoid 301 is turned off (ST24), and if there is no document 1 to be read next, the process is finished as it is. If there is a document 1 to be read next, surface reading is performed with the solenoid 301 kept off (ST26). This process is continued until the original 1 is exhausted (ST27).
When the double-sided reading mode is selected (ST22), the front side reading (ST28) and the back side reading (ST29) are performed while the solenoid 301 is kept on. This process is performed until the original 1 is exhausted (ST30). When the original is exhausted, the solenoid 301 is turned off (ST31), the second reading roller 26 is returned to the passing position, and the series of reading processes is completed.

  If the control as in this example is performed, even if the maximum number of sheets that can be read at one time (the maximum number of sheets that can be set) is 100 sheets, self-cleaning is always performed once every 100 sheets. Become.

  In addition, this operation may be such that self-cleaning is performed once for reading a predetermined number of documents instead of once for one reading process (for example, once every 20 documents are passed). FIG. 11 is a flowchart showing control for pressing a document against the second reading unit only once for a predetermined number during single-side reading.

  When the single-sided reading mode is selected (ST41), the solenoid 301 is turned off and the second reading roller 26 is arranged at the transport position (ST42). In this state, the front side is read (ST23), and the original 1 is allowed to pass while the second reading roller 26 is kept in the transport state. Then, for every x sheets (for example, 20 sheets), the solenoid 301 is turned on and the second reading roller 26 is moved to the transport position (ST45, ST46).

  When the double-sided reading mode is selected (ST41), the solenoid 301 is turned on to perform front side reading (ST48) and back side reading (ST49). This process is performed until the original 1 is exhausted (ST50). When the original 1 is exhausted, the solenoid 301 is turned off (ST51), the second reading roller 26 is returned to the passing position, and a series of reading processes is completed.

  Further, in the present example, when a jam occurs when reading a double-sided document, the conveyance path is widened if the second reading roller 26 can be moved to a separated conveyance position, so that the jam processing becomes easy. FIG. 12 is a flowchart showing the control state of the distance changing mechanism when a jam occurs. In this example, when the single-sided reading mode is selected (ST61), the solenoid 301 is turned off and the second reading roller 26 is arranged at the transport position (ST62). If a jam occurs in this state, the process is terminated as it is. If no jam occurs, the normal surface is read, and the original 1 is allowed to pass while the second reading roller 26 is in the transport state, and this process is performed for all the originals. (ST64).

  When the duplex reading mode is selected (ST61), the solenoid 301 is turned on to read the front side and the back side. When a jam occurs, the solenoid 301 is turned off (ST67), the second reading roller 26 is moved away to the transport position, the transport path is widened, and jam processing is performed. If the jam does not occur, the front and back sides are read until there is no original (ST68). If there is no original, the solenoid 301 is turned off (ST69) and the second reading roller 26 is passed through. The series of reading processing is terminated.

  Next, distance adjustment between the second reading unit 25 and the second reading roller 26 will be described. 13A and 13B are diagrams illustrating a driving state of the roller according to the embodiment, in which FIG. 13A is a schematic cross-sectional view when reading a document, FIG. 13B is a schematic cross-sectional view when transferring a document, and FIG. 4A is a schematic cross-sectional view when reading a document, and FIG. 4B is a schematic cross-sectional view when transferring the document.

  In this example, the shaft 26a of the second reading roller 26 is supported by the long hole portion 321 of the bearing 320, and when the 26a is placed in contact with the reading portion side end portion 321a of the long hole portion 321, the shaft is positioned at the reading position. When 26a is arranged in contact with the end 321b on the side opposite to the reading portion of the long hole portion 321, it is arranged at the transport position. As described above, if the position of the shaft 26a is regulated by the reading portion side end 321a and the counter reading portion side end 321b of the long hole portion 321, the second reading is performed from the center of the shaft 26a of the second reading roller 26. The distance to the reading surface contact portion of the portion 25 can be managed by the bearing 320 alone.

  If such a configuration is not adopted and the entire bearing 320 is moved, the second reading roller 26 is moved from the reading position (FIG. 14A) to the transport position (FIG. 14B) as shown in FIG. ) And move to the reading position again, the bearing 320 may collide with the second reading unit 25. If the surface of the second reading unit 25 is made of a fragile material such as glass, there is a risk of breakage. is there. According to this example, such a problem can be prevented.

  The second reading roller 26 preferably rotates in the transport direction in order to reduce a sliding load accompanying the passage of the document when the paper is passed. However, the second read roller 26 is spaced from the second reading unit 25 at the transport position. If sufficient, the second reading roller 26 does not need to be rotated. If the rotation of the second reading roller 26 is stopped at the transport position, the power consumption of the apparatus can be reduced accordingly.

  As described above, since the image reading apparatus can change the distance between the surface of the document reading unit and the facing portion guide, the state of the document conveyed between the surface of the document reading portion and the facing portion guide can be changed. .

  In addition, since the image reading apparatus keeps the distance between the surface of the original reading unit and the opposed guide at an appropriate time when reading an original, dust such as paper dust can stay on the reading line and read by a self-cleaning effect. Since the distance is widened when not, self-cleaning is unnecessary, and the coating on the surface of the reading unit can be prevented from being inadvertently deteriorated.

  In addition, since the image reading apparatus can change the distance between the surface of the original reading unit and the opposing unit guide with a simple configuration, the number of parts can be reduced and the cost can be reduced.

  In addition, since the image reading apparatus can operate gently when changing the distance between the surface of the document reading unit and the opposed unit guide, noise and vibration can be prevented.

  In addition, since the image reading apparatus can operate gently when changing the distance between the surface of the original reading unit and the opposed unit guide and can reduce the number of driving means for conveyance, the number of parts can be reduced and the cost can be reduced. You can go down.

  In addition, since the image reading apparatus can change the distance between the surface of the original reading unit and the opposing portion guide by switching between the single-sided reading mode / double-sided reading mode, self-cleaning is performed in the double-sided reading mode that requires reading, In the single-side mode that does not require reading, it is possible to prevent inadvertent deterioration of the coating on the surface of the reading unit.

  In addition, this image reading apparatus periodically performs self-cleaning even when used in a single-sided mode in order to keep the distance between the surface of the original reading unit and the opposing unit guide appropriate for each reading process. Retention can be prevented.

  In addition, this image reading device periodically performs self-cleaning even when used in a single-sided mode, in order to keep the distance between the surface of the original reading unit and the opposing unit guide appropriate for every given number of originals passed. It is possible to prevent the paper powder from staying.

  In addition, the image reading apparatus can easily perform jam processing since the surface of the document reading unit and the facing portion guide are separated from each other at the time of document jam.

  Further, in this image reading apparatus, since the opposed portion guide of the document reading portion is a roller, the sliding load during paper feeding is reduced.

  Further, this image reading apparatus can prevent noise and vibration at the time of separation and contact because the opposing portion guide of the document reading unit is a roller and the bearing for managing the gap does not move at the time of separation and contact.

  Further, since the rotation of the image reading apparatus is stopped when the surface of the document reading unit is separated from the opposing roller, the power consumption can be reduced.

  Since this image forming apparatus uses the above-described original reading apparatus, it is possible to prevent the coating on the reading surface from being worn, and to prevent the occurrence of vertical streaks due to the two types of dust having different properties over a long period of time. And good image formation can be performed.

  In the above example, the second reading unit has been described as an example of the document reading unit, but the present example can be applied to the first reading unit. Also, the present invention can be applied when there are one or three or more document reading means.

It is a schematic sectional drawing which shows the structure of an image reading apparatus. It is a block diagram which shows the whole control system of an image reading apparatus. It is a block diagram which shows the reading control system of an image reading apparatus. It is a schematic sectional drawing which shows the other example of a guide means. 4A and 4B are diagrams showing a roller as guide means, in which FIG. 4A is a schematic cross-sectional view when reading a document, and FIG. It is a schematic side view which shows the structure of a distance change mechanism. It is a schematic side view which shows the structure of the distance change mechanism which concerns on another example. It is a schematic side view which shows the structure of the distance change mechanism which concerns on another example. It is a flowchart which shows the control state of the distance change mechanism using a solenoid. 6 is a flowchart illustrating control for pressing a first document against a second reading unit during single-sided scanning. 6 is a flowchart showing control for pressing a document against a second reading unit once for a predetermined number of sheets during single-sided scanning. It is a flowchart which shows the control state of the distance change mechanism at the time of jam occurrence. 2A and 2B are diagrams illustrating a driving state of a roller according to the embodiment, in which FIG. 3A is a schematic cross-sectional view when reading a document, and FIG. 4A and 4B are diagrams illustrating a problem of roller driving, in which FIG. 4A is a schematic cross-sectional view when reading a document, and FIG.

Explanation of symbols

1 Document 2 Document Table 3 Movable Document Table 4 Set Filler 5 Set Sensor 7 Pickup Roller 8 Table Lifting Detection Sensor 9 Paper Feed Belt 10 Reverse Roller 11 Contact Sensor 12 Pull-Out Roller 13 Document Width Sensor 14 Intermediate Roller 15 Reading Entrance Sensor 16 Reading Entrance Roller 17 Registration sensor 20 Reading position 23 Exit roller 24 Paper discharge sensor 25 Second reading unit 26 Second reading roller 26a Shaft 27 CIS exit roller 28 Paper discharge roller 29 Paper discharge trays 30, 31 Document length detection sensor 30 Document length Detection sensor 100 ADF control unit 101 Pickup motor 102 Paper feed motor 103 Reading motor 104 Paper discharge motor 105 Bottom plate raising motor 107 I / F
108 Main unit operation unit 111 Main unit control unit 126 Guide member 200 Light source unit 201 Sensor chip 202 Gate 203 A / D converter 204 Image processing unit 205 Frame memory 206 Output control unit 207 IF circuit 301 Solenoid 302 Tension spring 303 Lever 304 Roller moving motor 305 Pulley 306 Gear 307 Lever 308 Motor 309 Pulley 310 Gear 311 Gear 312 Lever 313 Belt 314 Conveying roller 320 Bearing 321 Long hole 321a Reading part side end 321b Counter reading part side end A Document setting part B Separation feeding part C Resist Part D Turn part E First reading and conveying part F Second reading and conveying part G Paper discharging part H Stack part

Claims (9)

A document reading means for reading a document to be conveyed;
The document reading means has a first reading unit for reading the front side of the document and a second reading unit for reading the back side of the document,
A guide means provided opposite to the second reading unit , for guiding the document and setting a distance between the document and the second reading unit;
In an image reading apparatus comprising:
Reading surface of the second reading portion, the coating member having the dirt disassembly function, or can be varied Rutotomoni with a coating member having a hydrophilic, the distance between the guide means and the second reading unit It has a distance change mechanism ,
The document reading device includes a duplex mode for reading the front and back surfaces of a document, and a single-side mode for reading only the surface of a document,
The distance changing mechanism is
In the double-side mode, the distance between the guide means and the second reading unit is maintained at a distance suitable for document reading, and in the single-side mode, the distance between the guide means and the second reading unit is set to a document. While extending beyond the distance suitable for reading,
In the single-sided mode, the distance between the guide means and the second reading unit is maintained at a distance suitable for the document reading once per predetermined number of document reading operations.
An original reading apparatus characterized by the above. It said distance changing mechanism is pre-SL document reading apparatus according to claim 1, wherein Rukoto comprises a solenoid to widen the distance between the guide means and the second reading unit. 2. The document reading apparatus according to claim 1, wherein the distance changing mechanism includes a motor that increases a distance between the document reading unit and the guide unit. The motor includes a document reading apparatus according to claim 3, wherein that you have also serves as a motor for driving the conveying roller. The distance changing mechanism, when a document jam in a document reading apparatus according to any one of claims 1 to 4, characterized in Rukoto spread the distance between the guide means and the second reading unit. It said guide means, original reading apparatus according to any one of claims 1 to 5, characterized in Oh Rukoto a roller. And bearing is arranged in the roller end, by contacting a portion with said original reading means reading surface of the outer peripheral surface of the bearing, a suitable length of the roller and the document reading hand stage reading of the document the distance to the ground holding,
7. The document reading apparatus according to claim 6 , wherein when the distance between the roller and the document reading unit is increased, only the roller moves while the bearing is fixed . 8. The document reading apparatus according to claim 6 , wherein when the distance between the roller and the document reading unit is increased, the rotation of the roller is stopped . An image forming apparatus comprising: a document reading apparatus according to any of the preceding Ki請 Motomeko 1 to 8.