JP2015140253A - Sheet feeding apparatus and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To feed sheets while separating stacked sheets reliably.SOLUTION: A sheet feeding apparatus comprises: a return roller 4 which is in contact with a sheet fed by a feeding roller 2, and rotatable in a direction of returning the fed sheet; a separation member 3 which is disposed on a sheet feeding path between a place where the sheet is fed by the feeding roller 2 and a place where the sheet reaches the return roller 4, and has a slope part for abutting the sheets fed by the feeding roller 2 and separating the sheets one by one; and moving means for moving the separation member 3 to a separation position for separating the fed sheets and a retreat position which is moved in a direction apart from the fed sheets than the separation position.

Description

  The present invention relates to a sheet feeding apparatus that separates and feeds stacked sheets one by one and an image forming apparatus including the sheet feeding apparatus.

  The image forming apparatus includes a sheet feeding device that separates and feeds sheets one by one to the image forming unit. In such a sheet feeding apparatus, there is an apparatus using a slope portion as a system for separating sheets one by one. As shown in FIG. 9A, the sheet S stacked on the stacking unit 1 is conveyed by the feeding roller 2, and the sheet is pushed against the inclined surface of the separating member 3 on the downstream side of the feeding roller 2. In this case, only the uppermost sheet is separated and fed by the resistance force at that time (Cited document 1).

  Note that a sheet return roller 4 is provided on the downstream side of the separating member 3 in the sheet feeding direction in order to reliably separate sheets that are not separated into a single sheet by the separating member 3. The sheet return roller (hereinafter referred to as “return roller”) 4 rotates in a direction to return the fed sheet, and the return roller 4 returns the sheet S2 on the roller side, and FIG. As shown in FIG. 5, only the uppermost sheet S1 is separated and conveyed to the image forming unit.

U.S. Pat. No. 8,322,707

  However, in the method of separating the sheet using the separation slope and the return roller as described above, the protruding amount of the return roller 4 toward the sheet feeding path is small as shown in FIG. 9C. If set in such a manner, the separation performance deteriorates and double feeding may occur.

  Further, as shown in FIG. 9D, if the return roller 4 is set so that the amount of protrusion of the return roller 4 toward the sheet feeding path is increased, the separation performance is improved, but it is folded at the front end of the sheet S1 in contact with the return roller 4. There was a case where damage such as occurred. Therefore, it is necessary to strictly set and manage the return roller position accuracy.

  Further, since the optimum protrusion amount of the return roller position toward the feeding path differs depending on the rigidity and thickness of the sheet, there is a problem that the position accuracy of the return roller has to be further severe.

  Accordingly, the present invention has been made in view of such a current situation, and an object thereof is to provide a sheet feeding apparatus capable of reliably separating and feeding sheets and an image forming apparatus including the sheet feeding apparatus. To do.

  In order to achieve the above object, a typical configuration according to the present invention is a sheet feeding device that separates and feeds stacked sheets one by one, and a sheet feeding unit that feeds the stacked sheets. A separation rotating body that abuts on a sheet fed by the sheet feeding means and is rotatable in a direction to return the fed sheet; and a sheet fed by the sheet feeding means is attached to the separation rotating body A separating member that is disposed in a sheet feeding path, and has a slope portion for separating the sheets fed by the sheet feeding unit by contacting each other, and the separating member is fed And a moving unit that moves the sheet to a retreat position that moves in a direction away from the fed sheet from the separation position.

  In the present invention, when separating the fed sheet, the separation member is positioned at the separation position, and when the separation rotating body is rotating to return the double-fed sheet, the separation member is positioned at the retraction position. . Accordingly, the sheet can be fed while preventing the double feeding of the sheet without depending on the positional accuracy of the separation rotating body and without damaging the sheet.

1 is an explanatory diagram of an overall configuration of an image forming apparatus. FIG. 3 is a cross-sectional explanatory view of a sheet feeding device. FIG. 6 is an explanatory plan view of the sheet feeding device. It is a control block diagram of an actuator. It is explanatory drawing of the sheet feeding apparatus which moves a separation member by a cam mechanism. It is explanatory drawing of the sheet feeding apparatus which switches the rotation direction of the return roller which concerns on 2nd Embodiment. It is explanatory drawing of embodiment which enabled the position of the return roller to move. It is explanatory drawing of embodiment which a return roller moves according to the rotation direction of a return roller. It is a figure which shows the structure of the conventional feeding apparatus.

  Next, a sheet feeding apparatus according to an embodiment of the present invention and an image forming apparatus including the same will be described with reference to the drawings.

[First Embodiment]
<Image forming apparatus>
With reference to FIG. 1, an overall configuration of an image forming apparatus including a sheet feeding device according to a first embodiment of the present invention will be described.

  FIG. 1 is a schematic sectional view of the image forming apparatus. The image forming apparatus A roughly includes a sheet feeding device B that feeds the sheet S from the stacking unit, and an image forming unit that forms a toner image on the fed sheet S. The image forming unit includes an image transfer unit C that transfers the toner image to the sheet, and a fixing device D that fixes the toner image to the sheet.

  The image transfer unit C includes a cartridge 200 that can be attached to and detached from the image forming apparatus main body 100, a transfer roller 101, and a laser scanner unit 102. The cartridge 200 includes a photosensitive drum 201, a charger 202, and a developing unit 203.

  When a control unit (not shown) issues a print signal, the support member that supports the feeding roller 2 in the standby position swings and comes into contact with the uppermost sheet on which the feeding roller 2 is stacked. Then, the sheet S stacked on the sheet cassette 1 serving as a stacking unit is sent to the image transfer unit C by the rotation of the feeding roller 2.

  On the other hand, the surface of the photosensitive drum 201 is charged by a charger 202. Then, the laser scanner unit 102 emits laser light from a light source (not shown) provided inside, and irradiates the photosensitive drum with the laser light. As a result, a latent image is formed on the surface of the photosensitive drum. The latent image is developed by the developing unit 203 to form a toner image on the photosensitive drum 201. The toner image formed on the photosensitive drum 201 is transferred to the sheet S sent to the transfer nip portion formed between the photosensitive drum 201 and the transfer roller 101 by the conveying rollers 103 and 104.

  The sheet S on which the toner image has been transferred is sent to the fixing device D, and is heated and pressed at the fixing nip portion formed by the heating roller 105 and the pressure roller 106 of the fixing device D, and the toner on the sheet S The image is fixed on the sheet. The sheet S that has passed through the fixing device D is conveyed by the discharge rollers 107 and 108 and discharged onto the discharge tray 109.

<Sheet feeding device>
Next, the sheet feeding apparatus B will be described. FIG. 2 is a cross-sectional explanatory view of the sheet feeding apparatus according to the first embodiment, and FIG. 3 is a plan view. The sheet feeding apparatus has a plurality of sheets S stacked on the sheet cassette 1 and feeds them to the image transfer section C by separating them one by one.

  A feeding roller 2 is disposed on the upper portion of the sheet cassette 1. The feeding roller 2 serves as a sheet feeding unit that feeds the stacked sheets S. The feeding roller 2 rotates in the direction of the arrow in FIG. Send out the upper sheet.

  On the downstream side of the sheet feeding direction of the sheet feeding roller 2, there is provided a return roller 4 as a separation rotating body that can rotate in a direction in which the sheet S to be fed contacts and returns the sheet. Further, the separating member 3 is provided in the sheet feeding path while the sheet S fed by the feeding roller 2 reaches the returning roller 4 (on the downstream side of the feeding roller 2 and the upstream side of the returning roller 4). It has been. The separating member 3 is formed with a sloped portion against which a sheet fed by the feeding roller 2 abuts. When several sheets are fed out by the feeding roller 2, the slope portion is fed so that the uppermost sheet is separated by the resistance when the sheet is pushed up the inclined slope portion. It acts on.

  In rare cases, depending on the slope of the separation member 3, the sheet may not be separated into only one sheet. In that case, the sheet is conveyed onto the return roller 4 in a double-fed state like the sheets S1 and S2 in FIG. The return roller 4 is disposed at a position where the fed sheet abuts in the tangential direction and does not nip the sheet. By rotating the return roller 4 in the direction to return the fed sheet, the lower sheet S2 of the multi-fed sheet is returned, and only the uppermost sheet S1 is separated, and the image transfer section C To be sent to.

(Movement configuration of separation member)
The separation member 3 is provided so as to be pivotable about a shaft 3a, and is separated from the sheet fed from the separation position for separating the sheet fed by the rotation. It is possible to move to the retreat position that has moved in the direction of movement.

  In this embodiment, the moving means for moving the separating member 3 is constituted by an actuator. For example, a solenoid (drive source) is connected to the separation member 3, and the separation member 3 is rotated between a separation position and a retracted position by turning on and off the driving force of the solenoid.

  As shown in FIG. 4, the actuator operates when the control unit 21 turns on and off the solenoid 22 based on, for example, a detection result of the photosensor 20 that constitutes a sheet detection unit that detects a sheet to be fed. To do. The sheet detection means in the present embodiment includes a sensor lever 5 that rotates according to a fed sheet, and a sensor such as a photosensor that detects the rotation of the lever 5. The sensor lever 5 is arranged downstream of the contact position between the fed sheet and the return roller 4 in the sheet feeding direction, and is fed by the feeding roller 2 as shown in FIG. The front end of the sheet rotates by pushing the sensor lever 5. The sheet is detected by the sensor detecting this rotation. The sheet detection means is not limited to the above-described configuration, and may be a configuration in which the rotation of the sensor lever 5 is mechanically detected, a configuration in which the presence or absence of a sheet is detected by a photo sensor, or the like.

  The separating member 3 is in the separating position until the sheet detecting means detects the sheet, and when the sheet detecting means detects the sheet, the actuator operates in accordance with this and moves to the retracted position. Therefore, the separating member 3 moves from the separating position to the retracted position after the leading edge of the sheet fed by the feeding roller 2 reaches the return roller 4.

  When the separation member 3 is in the separation position, as shown in FIG. 2B, the separation member 3 is in a position having an angle suitable for separating the sheet fed by the slope portion. On the other hand, when the separating member 3 is in the retracted position, as shown in FIG. 2C, the separating member 3 is rotated in the direction of the arrow 7a and moved in a direction away from the fed sheet from the separating position. . When the separating member 3 moves to the retracted position, the sheet S2 that is being fed while being supported by the separating member 3 is not supported, and is pressed against the return roller 4 by the rigidity (strength of the waist) of the sheet. That is, when the separating member 3 is located at the retracted position, the contact pressure of the sheet with respect to the return roller 4 is higher than when the separating member 3 is located at the separated position, and the return force by the return roller 4 also acts greatly.

  The surfaces of the feed roller 2 and the return roller 4 are made of a rubber material having a relatively high frictional resistance. Therefore, the frictional force between the sheet S1 and the feeding roller 2 and the frictional force between the sheet S2 and the return roller 4 are larger than the frictional force between the uppermost sheet S1 and the lower sheet S2 that is double-fed. Therefore, the sheet S1 is overcome to the conveyance roller 103 by overcoming the friction force between the sheets without forming a nip, and the sheet S2 is returned to the upstream side in the conveyance direction.

  When the sheet S1 is conveyed to the conveying roller 103, the driving of the feeding roller 2 is cut off. Then, the feeding roller 2 is driven to rotate only while being in contact with the sheet S1, and the sheet S1 is conveyed. When the sheet is in contact with the sheet S2, the rotation of the feeding roller 2 is stopped. When the sheet S1 is further conveyed, the rear end of the sheet S1 passes through the sensor lever 5, and the sensor lever 5 enters the state shown in FIG. 2D, the actuator operates according to the sensor signal that detects this. The separating member 3 is rotated in the direction of the arrow 7b in FIG. Thereby, the separation member 3 returns to the separation position. Therefore, the separating member 3 moves from the retracted position to the separating position after the trailing edge of the sheet fed by the feeding roller 2 has passed the return roller 4.

  As described above, the separation member 3 and the return roller can be moved to the separation position for separating the sheet fed by the separation member 3 and the retracted position where the sheet reliably contacts the return roller 4. 4 can be reliably separated into one sheet. Further, even if the positional accuracy of the return roller 4 is not strict as in the prior art, it is possible to prevent the leading edge of the fed sheet from being bent.

<Other examples>
In the above description, the example in which the timing at which the separation member 3 is moved to the separation position and the retracted position is performed by sheet detection by the sheet detection unit has been described. However, the actuator may be operated after a predetermined time has elapsed from the start of sheet feeding by the feeding roller 2. Specifically, the actuator is operated to move the separation member 3 to the retracted position after the time required for the leading end of the sheet to pass through the contact position with the return roller 4 from the start of sheet feeding. Further, the actuator is operated to return the separation member 3 to the separation position after the time required for the trailing edge of the sheet to pass the return roller 4 from the start of sheet feeding. If it does in this way, components, such as a sheet detection sensor, can be omitted.

  In the above embodiment, the actuator is used as the moving means for moving the separating member 3. However, the separating member 3 is moved to the separating position and the retracted position by the cam mechanism interlocked with the driving timing of the feeding roller 2. Also good. For example, as shown in FIG. 5A, a cam 8 having two cam surfaces with different rotation radii is provided so as to rotate in conjunction with the rotation of the feeding roller 2. A cam contact portion 3 b provided on the separating member 3 is brought into contact with this cam surface, and is urged against the cam surface by a spring 9.

  In the case of the cam mechanism as described above, when the cam 8 rotates in conjunction with the feed roller 2 and the cam contact portion 3b is in contact with the small diameter portion of the cam surface as shown in FIG. The separation member 3 moves to the separation position. On the other hand, as shown in FIG. 5B, when the cam contact portion 3b is in contact with the large diameter portion of the cam surface, the separation member 3 moves to the retracted position. Thereby, when the feeding roller 2 is feeding the sheet to the inclined portion of the separating member 3, the sheet is moved to the separating position, and the sheet leading edge is moved to the retracted position immediately after passing the contact portion of the return roller 4. it can. This eliminates the need for the sheet detection sensor as described above, and eliminates the need to manage the sheet feeding time.

[Second Embodiment]
Next, an apparatus according to the second embodiment will be described with reference to FIG. Note that the basic configuration of the apparatus of the present embodiment is the same as that of the above-described embodiment, and thus a duplicate description is omitted.

  The surface of the return roller 4 is made of a rubber material having a relatively high frictional resistance. Therefore, if the leading edge of the sheet fed by the feeding roller 2 hits the return roller 4 rotating in the direction to return the sheet, the leading edge of the sheet may be bent (see FIG. 9D).

  Therefore, in this embodiment, a rotation switching unit that switches the rotation direction of the return roller 4 is provided. When the sheet feeding by the feeding roller 2 is started, the return roller 4 is rotated in the sheet feeding direction, and after the leading edge of the fed sheet has passed through the returning roller 4, the sheet is rotated in the direction to return the sheet. ing.

  Specifically, as shown in FIG. 6A, the return roller 4 is rotated simultaneously with the start of driving of the feeding roller 2. At this time, the rotation direction of the return roller 4 is a direction in which the sheet is fed. The leading edge of the fed sheet abuts on the return roller 4, but as described above, the return roller 4 rotates in the direction of feeding out the sheet, so that the leading edge of the sheet passes through the return roller 4 without breaking. When the fed sheet pushes up the sensor lever 5, the control unit switches the rotation direction of the return roller 4 to the reverse direction by a signal from the sensor that detects this. As a result, as shown in FIG. 6B, the uppermost sheet S1 is fed as it is even when the sheet is not completely separated on the inclined surface of the separating member 3 and is fed, but the lower sheet S2 is fed as it is. Is returned by the return roller 4 and separated from the sheet S1.

  When the separated sheet S1 is conveyed to the conveying roller 103, the driving force of the feeding roller 2 is interrupted. While the feeding roller 2 is in contact with the sheet S1, the sheet S1 is driven, and the sheet S1 is further conveyed. When the sheet S1 passes through the feeding roller 2, the feeding roller 2 stops.

  When the sheet S1 is further conveyed and the trailing end of the sheet S1 passes through the sensor lever 5 and the sensor lever 5 returns to the position shown in FIG. 6A, the control unit causes the return roller 4 to detect the signal from the sensor. The motor that drives is stopped.

  As described above, when the leading edge of the sheet to be fed comes into contact with the return roller 4, it is possible to reliably prevent the sheet from being bent forward by rotating the return roller 4 in the sheet feeding direction. Then, immediately after the leading end of the sheet passes through the return roller 4, the return roller 4 is rotated in the reverse direction (rotated in the direction to return the sheet), so that the multi-feed sheets can be reliably separated.

  In the present embodiment, as described in the first embodiment, the leading edge of the sheet is prevented from being folded without providing a moving means for moving the separating member 3 to the separating position and the retracted position according to the sheet feeding state. Sheet separation. However, if the moving means is provided so that the rotation direction of the return roller 4 is switched according to the sheet feeding state and the separation member 3 is moved between the separation position and the movement position, the leading edge of the sheet is more reliably folded. The sheet separation can be performed while preventing the above.

<Other examples>
In the above description, the example in which the timing for switching the rotation direction of the return roller 4 is performed by the sheet detection by the sheet detection unit. However, this also depends on the driving time of the feeding roller 2 as in the first embodiment described above. The reverse and stop timings may be determined. That is, the rotation direction of the return roller 4 may be switched from the direction in which the sheet is fed back to the direction in which the sheet is fed after a predetermined time has elapsed from the start of sheet feeding by the feeding roller 2. If it does in this way, components, such as a sheet detection sensor, can be omitted.

  Further, the return roller 4 may be provided so as to be movable between a separation position where it comes into contact with the fed sheet and a retract position where it is separated from the fed sheet. As a result, when the return roller 4 rotates in the sheet feeding direction, it moves to the retracted position so as not to contact the sheet, and when it rotates in the sheet returning direction, it moves to the separation position and securely moves to the sheet. So that it touches.

  For example, as shown in FIG. 7, the rotation shaft 4 a of the return roller 4 is attached to be movable along the long hole 10. Then, as shown in FIG. 8, the roller gear 11 fixed to the end portion in the longitudinal direction of the return roller 4 is engaged with the drive transmission gear 12.

  In the above configuration, as shown in FIG. 8A, when the drive transmission gear 12 is rotated counterclockwise in order to rotate the return roller 4 in the sheet feeding direction, the roller gear 11 is driven in the direction of the arrow 13a by the drive resistance. Be energized. For this reason, the rotating shaft 4 a of the return roller 4 moves to a position (retracted position) where it contacts the right end of the long hole 10. As a result, the leading edge of the fed sheet does not come into contact with the return roller 4.

  On the other hand, as shown in FIG. 8B, when the drive transmission gear 12 is rotated clockwise to rotate the return roller 4 in the direction to return the sheet, the roller gear 11 is urged in the direction of the arrow 13b by the drive resistance. The For this reason, the rotating shaft 4 a of the return roller 4 moves to a position (separation position) where it contacts the left end of the long hole 10. As a result, the sheet surely comes into contact with the return roller 4, and the double-feed sheet S <b> 2 is reliably returned by the rotation of the return roller 4.

  Note that when the double-fed sheets are separated by the return roller 4, the appropriate return force by the return roller 4 varies depending on the type of sheet (difference in basis weight, waist strength, material, etc.). Accordingly, the amount of protrusion to the sheet feeding path when the return roller 4 is at the separation position may be adjusted. For example, as shown in FIG. 8C, a swing stopper 14 that can swing around a shaft 14 a and can be fixed at the swing position is attached to the elongated hole 10. Thereby, by changing and fixing the angle of the swing stopper 14, the range in which the rotary shaft 4a of the return roller 4 can move through the long hole 10 can be changed, and the separation position can be set at any one of a plurality of locations. . Therefore, it is possible to change the separation position according to the type of the sheet and adjust the amount of protrusion to the sheet feeding path when the return roller 4 is at the separation position to an optimum value.

A ... Image forming apparatus B ... Sheet feeding device C ... Image transfer part D ... Fixing device S ... Sheet 1 ... Sheet cassette 2 ... Feed roller 2a ... Swing arm 3 ... Separation member 3a ... Cam contact part 4 ... Return Roller 4a: Rotating shaft 5 ... Sensor lever 5a ... Shaft 8 ... Cam 9 ... Spring 10 ... Elongate hole 11 ... Roller gear 12 ... Drive transmission gear 14 ... Swing stopper 14a ... Shaft 100 ... Image forming apparatus body 101 ... Transfer roller 102 ... Laser scanner unit 103, 104 ... Conveying roller 105 ... Heating roller 106 ... Pressure roller 107, 108 ... Discharge roller 109 ... Discharge tray 200 ... Cartridge 201 ... Photoconductor drum 202 ... Charger 203 ... Developer

Claims (16)

In a sheet feeding apparatus that separates and feeds stacked sheets one by one,
Sheet feeding means for feeding the stacked sheets;
A separation rotating body that abuts on the sheet fed by the sheet feeding means and is rotatable in a direction to return the fed sheet;
The sheet fed by the sheet feeding unit is disposed in a sheet feeding path between the sheet and the separation rotating body, and abuts the sheets fed by the sheet feeding unit to separate them one by one. A separating member having a slope portion of
Moving means for moving the separating member to a separating position for separating the fed sheet and a retracted position moved in a direction away from the fed sheet from the separating position;
A sheet feeding apparatus comprising:   The moving means moves the separating member from the separating position to the retracted position after the leading edge of the sheet fed by the sheet feeding means reaches the return roller. Sheet feeding device.   The moving means moves the separating member from the retracted position to the separating position after the trailing edge of the sheet fed by the sheet feeding means has passed through the return roller. The sheet feeding apparatus described in 1.   The sheet fed by the feeding means has a higher contact pressure with respect to the separation rotating body when the separation member is located at the retracted position than when the separation member is located at the separation position. The sheet feeding apparatus according to any one of claims 1 to 3. Sheet detecting means for detecting a sheet fed by the sheet feeding means;
The sheet according to any one of claims 1 to 4, wherein the moving means moves the separation member to the retracted position and the separation position based on a detection result of the sheet detecting means. Feeding device.   5. The moving device according to claim 1, wherein the moving unit moves the separation member to the retracted position after a lapse of a predetermined time from the start of sheet feeding by the sheet feeding unit. Sheet feeding device.   The moving means moves the separating member between the retracted position and the separating position by a cam mechanism interlocked with driving of the sheet feeding means. The sheet feeding apparatus according to item.   The sheet feeding apparatus according to claim 1, wherein the moving unit includes a driving source that generates a driving force and an actuator that operates by the driving force. In a sheet feeding apparatus that separates and feeds stacked sheets one by one,
Sheet feeding means for feeding the stacked sheets;
A separation rotator that abuts on the sheet fed by the feeding means and is rotatable in the direction of feeding and returning the fed sheet;
The sheet fed by the sheet feeding unit is disposed in a sheet feeding path between the sheet and the separation rotating body, and abuts the sheets fed by the sheet feeding unit to separate them one by one. A separating member having a slope portion of
Rotation switching means for switching the rotation direction of the separation rotator, wherein the separation rotator is rotated in the sheet feeding direction at the start of sheet feeding by the feeding means, and the leading end of the fed sheet is Rotation switching means for rotating the sheet in the direction to return the sheet after passing through the separation rotator,
A sheet feeding apparatus comprising: Sheet detecting means for detecting a sheet fed by the sheet feeding means;
The sheet feeding apparatus according to claim 9, wherein the rotation switching unit switches a rotation direction of the separation member based on a detection result of the sheet detection unit.   The rotation switching unit switches a rotation direction of the separation rotating body from a sheet feeding direction to a sheet returning direction after a predetermined time has elapsed from the start of sheet feeding by the sheet feeding unit. Or the sheet feeding apparatus according to claim 10.   The separation rotator is movably provided between a separation position that abuts on a fed sheet and a retreat position that is separated from the sheet. When the separation rotator rotates in a direction in which the sheet is fed, 12. The sheet feeding according to claim 9, wherein the sheet feeding unit moves to the retreat position and moves to the separation position when the separation rotating body rotates in a direction to return the sheet. apparatus.   The sheet feeding apparatus according to claim 12, wherein the separation position can be set at any one of a plurality of locations.   And a moving unit that moves the separating member to a separating position for separating the fed sheet and a retracted position that is moved away from the fed sheet from the separating position. The sheet feeding device according to any one of claims 9 to 13.   The moving means moves the separation member to the separation position when the separation rotating body rotates in the direction of feeding the sheet, and moves the separation member when rotated in the direction of returning the sheet. The sheet feeding apparatus according to claim 14, wherein the sheet feeding apparatus is moved to the retracted position. In an image forming apparatus for separating and feeding sheets stacked one by one by a sheet feeding device and forming an image on the fed sheet,
An image forming apparatus comprising the sheet feeding device according to claim 1 as the sheet feeding device.

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