JP2018131282A - Feeding apparatus and image forming apparatus - Google Patents

Abstract

Provided are a feeding device and an image forming apparatus in which cleaning of a feed roller and a separation roller is efficiently performed at an optimal frequency, and good feeding performance is maintained over time. An encoder 90 (or a detection means) for detecting a state in which a separation roller 55 rotates with the rotation of the feed roller 53 in a state where a sheet P is not sandwiched between nip portions of the feed roller 53 and the separation roller 55. , A detection unit 78) is provided. When the encoder 90 (or the detection unit 78) detects that the state where the separation roller 55 is rotated is poor, the sheet P is compared with the case where the state where the separation roller 55 is detected is good. The “idle drive mode” that is performed without feeding is controlled so as to increase the frequency of execution. [Selection] Figure 2

Description

  The present invention relates to a sheet feeding device that feeds a sheet, and an image forming apparatus such as a copying machine, a printer, a facsimile, or a complex machine or a printing machine including the same.

  Conventionally, in a feeding device installed in an image forming apparatus such as a copying machine, a printer, or a printing machine, a feed roller, a pickup roller, and a separation roller are installed, and the separation roller is driven via a torque limiter. An FRR paper feed system connected to a power source and an RF paper feed system in which a separation roller having no drive source is installed via a torque limiter are widely known (for example, Patent Document 1). -3)).

Specifically, such a feeding apparatus includes a feed roller that conveys a sheet accommodated in the apparatus in the feeding direction, and a sheet that is configured to be able to contact and separate from the sheet accommodated in the apparatus. And a separation roller for forming a nip portion in pressure contact with the feed roller to prevent double feeding of the sheet.
When one sheet is nipped in the nip portion, the separation roller is driven to rotate along the sheet feeding direction, and the sheet is fed in a desired feeding direction by the feed roller. On the other hand, when a plurality of sheets are sandwiched in the nip portion, the lower sheet is separated from the uppermost sheet by the separation roller so that only the uppermost sheet is fed along the rotation of the feed roller. Separated.

On the other hand, Patent Documents 1 and 2 disclose a technique for executing a “cleaning mode” at a predetermined timing in which the feed roller is rotated in a state where the separation roller is pressed against the feed roller in order to clean the surface of the feed roller. It is disclosed.
Japanese Patent Application Laid-Open No. 2003-228561 discloses a technique for bringing the pickup roller into contact with the friction force recovery member while driving the pickup roller every time the sheet stored in the sheet feeding cassette runs out to recover the frictional force of the pickup roller. ing.

Since the conventional feeding device rotates the feed roller with the separation roller pressed against the feed roller at a predetermined timing, foreign matters such as paper dust and calcium carbonate adhering to the feed roller and the separation roller are removed. Therefore, it can be expected to some extent that the good feeding performance is maintained.
However, the conventional feeding device has excessively cleaned the feed roller and the separation roller or has insufficient cleaning. That is, the feed roller and the separation roller have not been efficiently cleaned at an optimal frequency.

  The present invention has been made to solve the above-described problems. The feed roller and the separation roller are efficiently cleaned at an optimal frequency, and good feeding performance is maintained over time. Another object of the present invention is to provide a feeding device and an image forming apparatus.

  The feeding device according to the present invention is installed so as to form a nip portion between a feed roller that rotates along the sheet feeding direction and feeds the sheet in the feeding direction, and the feed roller. When a sheet is sandwiched in the nip portion and when a sheet is not sandwiched in the nip portion, the sheet rotates in the feeding direction, and a plurality of sheets are placed in the nip portion. When the sheet is sandwiched, the lower sheet is moved with respect to the uppermost sheet so that only the uppermost sheet among the plurality of sheets is fed in the feeding direction along the rotation of the feed roller. A separation roller to be separated; and when the feed roller rotates along the feeding direction in a state where no sheet is sandwiched in the nip portion, Detecting means for detecting a state in which the roller is rotated along the feeding direction, and an idle driving mode in which the feed roller is rotated along the feeding direction without feeding a sheet is predetermined. When the detection means detects that the state where the separation roller is rotated is bad, compared to the case where the detection means detects that the state where the separation roller is rotated is good. Control is performed so as to increase the frequency with which the idle drive mode is executed.

  According to the present invention, it is possible to provide a feeding device and an image forming apparatus in which cleaning of a feed roller and a separation roller is efficiently performed at an optimal frequency, and good feeding performance is maintained over time. be able to.

1 is an overall configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention. It is a schematic block diagram which shows a feeding apparatus. It is a schematic block diagram which shows the drive system of a feeder. It is the schematic which shows operation | movement of the pick-up roller contact / separation mechanism in a feeder. FIG. 6 is a schematic diagram illustrating an operation when a plurality of sheets are sandwiched in a nip portion in the feeding device. 6 is a graph showing changes in motor voltage when a plurality of sheets are sandwiched in a nip portion in the feeding device. It is a figure which shows the state by which idle driving mode was performed in the feeder. It is a flowchart which shows the control at the time of idle drive mode. It is a figure which shows the state in which the rotation defect occurred in the separation roller. They are (A) a graph showing a change in encoder output and (B) a graph showing a change in applied current of a DC motor when a rotation failure occurs in the separation roller.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.

First, the overall configuration and operation of the image forming apparatus 1 will be described with reference to FIG.
In FIG. 1, 1 is a copying machine as an image forming apparatus, 2 is a document reading unit that optically reads image information of a document D, and 3 is a photosensitive member that exposes light L based on the image information read by the document reading unit 2. An exposure unit for irradiating the drum 5, 4 is an image forming unit for forming a toner image (image) on the photoconductive drum 5, and 7 is a toner image formed on the photoconductive drum 5 on a sheet P (recording medium). A transfer section (image forming section) for transferring, 10 a document transport section (automatic document transport apparatus) for transporting the set document D to the document reading section 2, and 12 and 13 are sheets P accommodated in a sheet feeding cassette. A feeding device 16 for feeding, a manual feeding device for feeding a sheet P manually set by a user, 17 a registration roller (timing roller) for conveying the sheet P toward the transfer unit 7, and 20 for a sheet P Toner image carried on top A fixing roller installed in the fixing device 20, a pressure roller installed in the fixing device 20, and a discharge 31 on which the sheet P discharged from the apparatus main body 1 is stacked. The paper trays 42 and 43 are placed on the feeding devices 12 and 13 so that they can be raised and lowered (lifting plates), and 52 is a feeding means installed in each of the feeding devices 12, 13, and 16. A feeding mechanism 80 indicates an operation panel (operation display panel) installed on the exterior portion of the apparatus main body 1 in order to display or operate the image forming apparatus 1.

With reference to FIG. 1, an operation during normal image formation in the image forming apparatus main body 1 will be described.
First, the document D is transported (feeded) from the document table in the direction of the arrow in the drawing by the transport rollers of the document transport unit 10 and passes over the document reading unit 2. At this time, the document reading unit 2 optically reads the image information of the document D passing above.
Then, the optical image information read by the document reading unit 2 is converted into an electric signal and then transmitted to the exposure unit 3 (writing unit). Then, exposure light L such as laser light based on the image information of the electrical signal is emitted from the exposure unit 3 toward the photosensitive drum 5 of the image forming unit 4.

On the other hand, in the image forming unit 4, the photosensitive drum 5 is rotated in the clockwise direction in FIG. 1, and image information is transferred onto the photosensitive drum 5 through a predetermined image forming process (charging process, exposure process, development process). An image (toner image) corresponding to is formed.
Thereafter, the image formed on the photosensitive drum 5 is transferred onto the sheet P conveyed by the registration roller 17 in the transfer unit 7 as an image forming unit.

On the other hand, the sheet P conveyed to the transfer unit 7 (image forming unit) operates as follows.
First, one of the plurality of feeding devices 12 and 13 of the image forming apparatus main body 1 is automatically or manually selected (for example, it is assumed that the lower feeding device 13 is selected). . Then, the uppermost sheet P stored in the feeding device 13 is fed by the feeding mechanism 52 and conveyed toward the conveying path K. Thereafter, the sheet P passes through a conveyance path K in which a plurality of conveyance rollers are arranged, and reaches the position of the registration roller 17.
When the feeding device 16 (manual feeding device) installed on the side of the apparatus main body 1 is selected, the sheet placed on the placement unit (manual tray) of the feeding device 16 by the user. P (the uppermost sheet P when a plurality of sheets P are stacked) is fed toward the conveyance path by the feeding mechanism 52 (feeding means) and reaches the position of the registration roller 17. It will be.

The sheet P that has reached the position of the registration roller 17 is conveyed toward the transfer unit 7 (image forming unit) at the same timing in order to align with the image formed on the photosensitive drum 5.
The sheet P after the transfer process passes through the position of the transfer unit 7 and then reaches the fixing device 20 through the conveyance path. The sheet P that has reached the fixing device 20 is fed between the fixing roller 21 and the pressure roller 22, and the toner image is fixed by the heat received from the fixing roller 21 and the pressure received from both members 21 and 22. (This is a fixing process). The sheet P after the fixing process on which the toner image has been fixed is delivered from between the fixing roller 21 and the pressure roller 22 (a fixing nip), and then discharged from the image forming apparatus main body 1 to be an output image. As shown in FIG.
Thus, a series of image forming processes is completed.

Next, the feeding device according to the present embodiment will be described in detail with reference to FIGS.
Hereinafter, the lower feeding device 13 among the plurality of feeding devices 12 and 13 inscribed in the apparatus main body 1 will be described. However, the upper feeding device 12 also has a lower installation except that the installation position is different. Since the configuration is almost the same as that of the feeding device 13, description thereof is omitted.

Referring to FIG. 2 and the like, the feeding device 13 is fed with a placement portion 43 (lift plate) formed so that a plurality of sheets P can be stacked, and the sheet P placed on the placement portion 43. A feeding mechanism 52 as a feeding means for feeding is installed.
The mounting portion 43 is configured to move up and down by rotating in a forward and reverse direction around a rotation center shaft 43a (see FIG. 1).
2 to 4, the feeding mechanism 52 includes a feed roller 53, a pickup roller 54, a separation roller 55, a torque limiter 56, a DC motor 77 (drive source), drive transmission units 60 to 68, an encoder. 90 (detection means), contact / separation mechanisms 58, 72, 73, and the like.

The feed roller 53 is installed on the leading end side in the feeding direction (the white arrow direction in FIG. 2) with respect to the sheet P placed on the placement unit 43, and is in contact with the upper surface of the sheet P. The sheet P is rotated along the feeding direction of the sheet P (counterclockwise rotation in FIG. 2) and fed in the feeding direction indicated by a one-dot chain line arrow.
Referring to FIG. 3, feed roller 53 is provided with two-stage gears 65 and 66 at its shaft portion. Then, the drive is transmitted from the DC motor 77 (drive motor) to the lower gear 65 of the two-stage gear via the motor pulley 60, the timing belt 61, the pulley 63 of the pulleys and the second-stage gears 62 to 64, and the lower gear 62. The roller 53 is rotationally driven counterclockwise in FIG.

The pickup roller 54 rotates in the counterclockwise direction in FIG. 2 along the traveling direction while abutting on the surface (upper surface) of the sheet P placed on the placement unit 43 to feed the sheet P. It is conveyed toward the position of the roller 53.
Referring to FIG. 3, the pickup roller 54 has a gear 68 installed on its shaft portion. Then, the drive is transmitted from the DC motor 77 to the gear 68 through the motor pulley 60, the timing belt 61, the pulleys and the second gears 62 to 64, the second gears 65 and 66, and the idler gear 67, and the pickup roller 54 is shown in FIG. It is driven to rotate counterclockwise.

The pickup roller 54 is configured to be able to contact and separate from the sheet P (uppermost sheet P1) placed on the placement unit 43. That is, the pickup roller 54 is in a retracted position where it does not contact the sheet P placed on the placing portion 43 (the position shown in FIG. 4B), and a contact position where the pickup roller 54 comes into contact (FIG. 2). , And the position shown in FIG. 4A).
Specifically, referring to FIG. 4 and the like, the pickup roller 54 is rotatably held by the arm 58. The arm 58 is rotatably held on the rotation shaft of the feed roller 53. The projecting portion 58 a of the arm 58 has a spring 73 (biasing member) that urges the pickup roller 54 to move to the retracted position, and a contact position that resists the urging force of the spring 73. A solenoid 72 to be moved is connected. When the solenoid 72 is turned on under the control of the control unit 70, the pickup roller 54 is moved to the contact position as shown in FIG. 4A, and the solenoid 72 is turned off. As shown in FIG. 4B, the pickup roller 54 moves to the retracted position.
The idler gear 67 described above with reference to FIG. 3 is installed on the arm 58 and maintains the meshing state with the gear 68 of the pickup roller 54 and the meshing state with the gear 66 of the feed roller 53. It will rotate with 58.

The separation roller 55 is installed so as to form a nip portion with the feed roller 53.
The separation roller 55 rotates along the feeding direction when one sheet P is sandwiched in the nip portion and when the sheet P is not sandwiched in the nip portion (FIG. 2). In the direction of the broken arrow in FIG.
On the other hand, when a plurality of sheets P are sandwiched in the nip portion, the separation roller 55 causes the uppermost sheet P1 of the plurality of sheets P to move in the feeding direction along with the rotation of the feed roller 53. The lower sheet P2 is separated from the uppermost sheet P1 so as to be fed. Specifically, when a plurality of sheets P are sandwiched in the nip portion, the separation roller 55 feeds the uppermost sheet P1 in the feeding direction along the rotation of the feed roller 53. Rotates along the opposite direction so that the lower sheet P2 is conveyed in the opposite direction to the feeding direction (in the direction indicated by the solid line arrow in FIG. 2 and rotates counterclockwise) ).

Specifically, referring to FIG. 3, the separation roller 55 is provided with a gear 69, a torque limiter 56, and a detection plate 92 at the shaft portion thereof. Then, the drive is transmitted from the DC motor 77 to the gear 69 via the motor pulley 60, the timing belt 61, the pulley 63 of the pulleys and the second gears 62 to 64, and the upper gear 64, and further, the drive is transmitted via the torque limiter 56. It is transmitted to the separation roller 55 or blocked.
The torque limiter 56 is configured such that the separation roller 55 idles relative to the torque limiter 56 when a rotational load exceeding a predetermined value is applied to the separation roller 55.

Specifically, the torque limiter 56 is configured such that when one sheet P is sandwiched in the nip portion (the contact portion between the feed roller 53 and the separation roller 55) and when the sheet P is sandwiched in the nip portion. When there is not, the rotational load applied to the separation roller 55 becomes relatively large, so that the drive transmission from the DC motor 77 to the separation roller 55 is cut off. At this time, the separation roller 55 is idled with respect to the torque limiter 56, and is rotated along the clockwise direction of FIG.
On the other hand, the torque limiter 56 is separated from the DC motor 77 because the rotational load applied to the separation roller 55 becomes relatively small due to slippage between the sheets P when a plurality of sheets P are held in the nip portion. Drive is transmitted to the roller 55. As a result, the separation roller 55 is driven to rotate counterclockwise in FIG. 2, and the lower sheet excluding the uppermost sheet P1 among the plurality of sheets P sandwiched between the nip portions is reversed (FIG. 5 ( B) in the direction of the black arrow.) And returned to the mounting portion 43.
With such a configuration, one sheet P is fed in the feeding direction (conveyance direction) without being fed from the nip portion between the feed roller 53 and the separation roller 55.

  In the present embodiment, the feed roller 53, the pickup roller 54, and the separation roller 55 each have a roller portion (roller portion) formed of a rubber material (or a resin material) on the shaft portion. It is formed by dividing into a plurality of parts. Further, the feed roller 53, the pickup roller 54, and the separation roller 55 are formed so that the roller portion can be attached to and detached from the shaft portion (replaceable), and the maintenance of the roller portion can be facilitated. Yes.

As described with reference to FIG. 3, the DC motor 77 functions as a drive source (motor) that rotationally drives the feed roller 53, the pickup roller 54, and the separation roller 55.
In particular, in the present embodiment, the DC motor 77 as a drive source is feedback controlled so that the rotational speed of the motor shaft becomes a predetermined value. Specifically, the current (or voltage) applied to the DC motor 77 is adjusted by PWM control by the control unit 70 so that the rotational speed of the DC motor 77 is constant regardless of load fluctuations. (See FIG. 6). Specifically, the current (or voltage) applied to the DC motor 77 is adjusted to be large when the load applied to the DC motor 77 is large, and is applied to the DC motor 77 when the load applied to the DC motor 77 is small. The current (or voltage) to be adjusted is adjusted to be small, and the rotational speed of the DC motor 77 is made constant.
Thereby, stable feeding by the feeding mechanism 52 becomes possible.

Here, referring to FIG. 3, encoder 90 that detects the rotation speed and rotation direction of separation roller 55 is installed in feeding device 13 in the present embodiment.
The encoder 90 includes a detected plate 92 that rotates with the separation roller 55 (a plurality of holes are formed in the circumferential direction at regular intervals on the outer periphery thereof), and a photo that detects the holes of the detected plate 92. And a sensor 91. In this embodiment, the frequency of execution of the “idle drive mode” is varied depending on the change in the rotational speed of the separation roller 55 that is detected by the encoder 90. This will be described in detail later. To do.

Here, the feeding device 13 according to the present embodiment allows the pickup roller 54 to contact the uppermost sheet P stacked on the placement unit 43 so that the sheets P stacked on the placement unit 43 can be brought into contact with each other. Depending on the number of sheets, the placement unit 43 moves up and down. Then, after the pickup roller 54 is lowered to a position where it comes into contact with the upper surface of the sheet P placed on the placement unit 43 whose vertical position is adjusted, the sheet P feeding operation is performed.
An inlet guide plate is installed between the placing portion 43 and the nip portion between the feed roller 53 and the separation roller 55.
Further, the feeding device 13 according to the present embodiment is provided with a side fence that regulates the position of the sheet P placed on the placement unit 43 in the width direction (in the direction perpendicular to the sheet of FIG. 2). ing. The side fences are respectively installed at both ends in the width direction so as to sandwich the sheet P, and are configured to be movable in the width direction according to the size in the width direction of the sheet P by a manual movement mechanism.
Further, the feeding device 13 according to the present embodiment is provided with an end fence that regulates the position of the sheet P placed on the placement unit 43 in the feeding direction (the left-right direction in FIG. 2). ing. The end fence is installed so as to contact the rear end of the sheet P in the feeding direction, and is configured to be movable in the feeding direction according to the size of the sheet P in the feeding direction by a manual movement mechanism.

In the feeding device 13 configured as described above, when the sheet P is not set on the placement unit 43, the state is detected by the end detection sensor 95, and the pickup roller is controlled by the control of the solenoid 72 by the control unit 70. 54 is in the retracted position to the retracted position (the position shown in FIG. 4B).
When the sheet P is set on the placement unit 43, the state is detected by the end detection sensor 95, and the pickup roller 54 is moved from the retracted position to the contact position (see FIG. It is the position shown in A).
Then, as shown in FIG. 2, the pickup roller 54 starts to rotate counterclockwise with the pickup roller 54 in contact with the upper surface of the uppermost sheet P placed on the placement portion 43, and The rotation of the feed roller 53 and the separation roller 55 is started at the same timing. As a result, the uppermost sheet P of the sheet bundle placed on the placement portion 43 by the pickup roller 54 is conveyed toward the nip portion between the feed roller 53 and the separation roller 55, and further from the nip portion. One sheet P is separated and conveyed toward the image forming unit.
Further, when all the sheets P placed on the placement unit 43 are fed and the sheets P are not set on the placement unit 43, the state is detected by the end detection sensor 95, and the control unit The pickup roller 54 is again moved to the retracted position by the control of the solenoid 72 by 70 (the state shown in FIG. 4B).

FIG. 5 illustrates an example of the operation of the feeding device 13 and is a schematic diagram illustrating the operation when a plurality of sheets P are sandwiched in the nip portion.
First, as shown in FIG. 5A, when the sheet P is set on the placement unit 43, the pickup roller 54 is controlled by the control of the solenoid 72 by the control unit 70 after the placement unit 43 is raised to the optimum position. Is moved from the retracted position toward the contact position (the position shown in FIG. 5A). Then, as shown in FIG. 5A, the pickup roller 54 starts to rotate counterclockwise with the pickup roller 54 in contact with the upper surface of the uppermost sheet P1 placed on the placement portion 43. Then, the sheets P1 and P2 placed on the placement portion 43 by the pickup roller 54 are conveyed toward the nip portion between the feed roller 53 and the separation roller 55. At this time, it is assumed that two sheets P1 and P2 have been double-fed. Further, when the sheets P1 and P2 are not sandwiched between the nip portions, the torque limiter 56 is idling, and the separation roller 55 rotates in the clockwise direction.

As shown in FIG. 5B, when the two sheets P1 and P2 that have been overrun are conveyed to the nip portion, the pickup roller 54 is moved to the retracted position again. At this time, since the two sheets P1 and P2 are sandwiched between the nip portions, the torque limiter 56 is connected, and the separation roller 55 starts to rotate counterclockwise.
Then, as the separation roller 55 rotates counterclockwise, the lower sheet P2 is conveyed in the black arrow direction so as to follow the rotation of the separation roller 55 as shown in FIG. Returned to 43.) The upper sheet P1 (uppermost sheet P1) is conveyed in the direction of the white arrow along the rotation of the feed roller 53 (conveyed toward the conveyance path of the image forming apparatus main body 1).
Then, as shown in FIG. 5D, when the lower sheet P2 returned toward the placement portion 43 by the separation roller 55 passes through the nip portion, the torque limiter 56 is idled again and separated. The roller 55 rotates again in the clockwise direction.
When one sheet P is nipped without a plurality of sheets P being nipped in the nip portion from the state of FIG. 5A, the separation roller 55 is moved as shown in FIGS. 5B and 5C. Without rotating in the counterclockwise direction, the uppermost sheet P1 is conveyed in the direction of the white arrow as shown in FIG.

Hereinafter, a characteristic configuration and operation of the feeding device 13 (image forming apparatus 1) according to the present embodiment will be described.
The feeding device 13 in the present embodiment is provided with an encoder 90. The encoder 90 is rotated when the feed roller 53 rotates in the counterclockwise direction in FIGS. 2 to 6 along the feeding direction in a state where the sheet P is not sandwiched between the nip portions of the feed roller 53 and the separation roller 55. In addition, it functions as a detecting means for detecting a state in which the separation roller 55 is rotated along the feeding direction (the degree of rotation) as the feed roller 53 rotates. As described above with reference to FIG. 3, the encoder 90 as the detecting means detects the rotational speed (or change in rotational speed) of the separation roller 55.

Specifically, as shown in FIG. 7, the rotation of the feed roller 53 is performed in a state where the sheet P is not sandwiched between the nip portions of the feed roller 53 and the separation roller 55 (the sheet P is not fed). At the same time, when the separation roller 55 is rotated (driven rotation) and the encoder 90 (detecting means) detects that the rotation speed of the separation roller 55 is lower than that in the normal state, the separation roller 55 is rotated. It is determined that the condition (degree of accompanying) has deteriorated and has not been rotated well.
Thus, when the accompanying rotation failure of the separation roller 55 occurs, the output of the encoder 90 (photo sensor 91) changes as shown in FIG. In other words, the separation roller 55 slips and the rotational speed is lower than that in the normal state with respect to the “normal time” encoder output period H0 in which the separation roller 55 rotates at substantially the same speed as the feed roller 53 without slipping. The period H1 of the encoder output at the time of “rotation failure” becomes longer depending on the degree.

In addition, as an aspect of the rotation failure of the separation roller 55 that occurs in the situation of being rotated, first, as shown in FIG. 9A, there is a state in which the separation roller 55 rotates at a lower speed than normal. When the state further deteriorates, the separation roller 55 stops rotating as shown in FIG. 9B, or the separation roller 55 rotates reversely as shown in FIG. 9C. Become.
In any aspect, if a rotation failure occurs in the separation roller 55, when the sheet P is fed toward the nip portion between the feed roller 53 and the separation roller 55, the broken line in FIG. The phenomenon that the leading edge of the sheet P collides with the entrance of the enclosed nip portion occurs, and the sheet P is not smoothly fed out from the nip portion, or the sheet P is jammed (paper jam) at the nip portion. Become.

  Such a rotation failure of the separation roller 55 is caused by foreign matters such as paper powder and calcium carbonate generated from the sheet P adhering to the roller surfaces (formed of a rubber material) of the separation roller 55 and the feed roller 53. This is caused by a decrease in the frictional force on the roller surface.

  Then, the rotation failure of the separation roller 55 is caused by a sheet detection sensor 96 (detecting the position of the sheet P) that detects that the sheet P that should reach the predetermined position downstream in the feeding direction with respect to the nip portion does not reach the predetermined time. An optical sensor that optically detects the passing sheet P, and can also be detected to some extent. That is, the time for the sheet P to reach the position of the sheet detection sensor 96 without being smoothly fed out from the nip portion is delayed, or the sheet P jams (paper jams) at the nip portion, and the sheet detection sensor 96 When the position does not reach the position, the state is detected by the sheet detection sensor 96, and the state in which the accompanying failure of the separation roller 55 occurs can be grasped.

However, when foreign matter adheres to the roller surfaces of the separation roller 55 and the feed roller 53, the frictional force on the roller surface is not so low and the rotation speed of the separation roller 55 is not so low. There is almost no delay of the sheet P reaching the position of the sheet detection sensor 96, and the sheet detection sensor 96 cannot grasp the state in which the accompanying rotation failure of the separation roller 55 occurs. That is, the sheet detection sensor 96 cannot accurately detect the accompanying rotation failure of the separation roller 55 (dirt on the roller surfaces of the separation roller 55 and the feed roller 53).
On the other hand, in the present embodiment, since the encoder 90 (detecting means) directly detects the state of the separation roller 55 (the degree of rotation), the slight rotation failure of the separation roller 55 is detected. Even (stains on the roller surfaces of the separation roller 55 and the feed roller 53) can be accurately detected.

Further supplementary explanation will be given below.
A sheet feeding system (the FRR sheet feeding type as in the present embodiment, which feeds the sheet P by separating the sheet P into one sheet by rotating the separation roller 55 via the torque limiter 56 with respect to the feed roller 53, The feeding device of the RF paper feeding method described in Patent Document 1) is that the feeding roller 53 and the separation roller 55 have the separation roller 55 of which the frictional force against the sheet P is not reduced so much. Carrying ability may decrease.
This is because, when the irregularities on the surface of the rubber roller of the feed roller 53 and the separation roller 55 are reduced, and particle components such as calcium carbonate are present between the rubber rollers, the particle components become irregularities on the sheet P. This is because it may be hidden. In such a state, even when the conveyance force (friction coefficient) between the rubber roller and the sheet P is sufficient, when the rubber rollers come into contact with each other, the floating particles are not caught in the recesses on the surface of the rubber roller, and between the rollers. , The conveyance force (coefficient of friction) between the rubber rollers decreases, and the followability decreases.
In such a state, since the sheet conveying force of the feed roller 53 is not reduced, the detection timing of the sheet detection sensor 96 that detects the arrival time of the leading edge of the sheet during feeding does not become an abnormally delayed state. In addition, it is not possible to detect a rotation failure of the separation roller 55.
On the other hand, in this embodiment, as described above, it is possible to accurately detect the accompanying failure of the separation roller 55 by the encoder 90 (detection means).

  In the present specification and the like, the state in which the separation roller 55 is rotated (the degree of rotation) detected by the detection unit in this manner is appropriately referred to as “forward rotation” or “rotation”. I will call you. The forward rotation property (rotating property) of the separation roller 55 is to detect directly or indirectly the amount of rotation of the separation roller 55 per unit time, the time required for the separation roller 55 to rotate a predetermined number of times, and the like. Can be judged.

Here, in the present embodiment, the encoder 90 is used as a detection means for detecting the forward rotation property (rotating property) of the separation roller 55.
On the other hand, as a detection means for detecting the forward rotation property of the separation roller 55, a detection unit 78 (see FIG. 2) that is a means for detecting a current (or voltage) applied to the DC motor 77 can be used. It can also be used.
Specifically, the detection unit 78 (detection means) detects a load applied to the DC motor 77 by detecting a change in the current (or voltage) applied to the DC motor 77 as described above with reference to FIG. Detects torque changes. As the detector 78, a current measuring device (or voltage measuring device) that detects a change in current (or voltage) applied to the DC motor 77 can be used.

Specifically, as shown in FIG. 7, the rotation of the feed roller 53 is performed in a state where the sheet P is not sandwiched between the nip portions of the feed roller 53 and the separation roller 55 (the sheet P is not fed). At the same time, when the separation roller 55 is rotating (driven rotation) and the state where the current applied to the DC motor 77 is reduced by the detection unit 78 (detection means) compared to the normal state, the separation roller 55 is detected. It is determined that the state of being carried around (the degree of carrying around) has deteriorated and has not been carried around well.
In this way, when the follow-up failure of the separation roller 55 occurs, the DC motor applied current changes as shown in FIG. That is, with respect to the “normal time” DC motor applied current that rotates at substantially the same speed as the feed roller 53 without slipping, the separation roller 55 slips and the rotational speed is lower than normal. The DC motor applied current at the time of poor rotation decreases depending on the degree.
As described above, even when the detection unit 78 is used as the detection unit, it is possible to accurately detect the accompanying rotation failure of the separation roller 55 (dirt on the surface of the separation roller 55 and the feed roller 53).

Here, in the present embodiment, as shown in FIG. 7, the “idle drive mode” in which the feed roller 53 is rotated along the feeding direction without feeding the sheet P is executed at a predetermined timing. . In the “idle drive mode”, the DC motor 77 is operated without performing the sheet P feeding operation, and the feed roller 53 and the separation roller 55 are idly rotated. At this time, the feed roller 53 rotates counterclockwise in FIG. 7, and the separation roller 55 is driven (rotated) in the clockwise direction in FIG.
By performing the “idle drive mode” in this way, the roller surfaces of the separation roller 55 and the feed roller 53 are rubbed directly, and foreign matters such as paper dust and calcium carbonate adhering to the roller surfaces are removed. It will be removed to be scraped off. That is, the “idle drive mode” is performed for cleaning the roller surfaces of the separation roller 55 and the feed roller 53. Then, by performing the “idle drive mode”, the friction coefficient of the roller surface of the separation roller 55 and the feed roller 53 is restored to the original state, and the forward rotation property (rotating property) of the separation roller 55 is also restored to the original state. It will be. Therefore, by performing the “idle driving mode”, the accompanying failure of the separation roller 55 is reduced.

  In the present embodiment, the encoder 90 (or the detection unit 78) separates the encoder 90 (or the detection unit 78) when the separation roller 55 is detected to be in a poor state. Control is performed such that the frequency of the “idle drive mode” is increased as compared with the case where it is detected that the state where the roller 55 is rotated is good.

Specifically, as described above, the placement unit 43 of the feeding device 13 is provided with an end detection sensor 95 that detects a state in which all the sheets P accommodated in the feeding device 13 are exhausted. Yes.
Then, the “idle drive mode” is executed when the number of times detected by the end detection sensor 95 reaches N times (a value that can be varied in the control and is also referred to as “N value” as appropriate). So that it is controlled. That is, after the sheet P is emptied in the feeding device 13, the operation of replenishing the sheet P is performed N−1 times, and immediately after the state where the sheet P is emptied for the Nth time is detected. The “idle drive mode” is executed. As described above, by executing the idle driving mode immediately after the sheet P in the feeding device 13 is in the end state, it is difficult to temporally prevent the printing operation performed by the user (the waiting time is less likely to occur).
When the encoder 90 (or the detection unit 78) detects that the separation roller 55 is in a poor state, the encoder 90 (or the detection unit 78) has a good state in which the separation roller 55 is rotated. Compared with the case where it is detected, the above N times (N value) is controlled to be a small value. That is, when it is determined that the forward rotation property of the separation roller 55 has been lowered, the N times (N value) is lowered, and the frequency of execution of the idling mode increases, and the separation roller 55 and the feed roller 53 Cleaning is frequently performed.

More specifically, when the value R detected by the encoder 90 (or the detection unit 78) is smaller than the normal value R0 by exceeding a predetermined threshold A (R0−R> A). ) Is controlled so as to increase the frequency at which the “idle drive mode” is executed. That is, the “idle drive mode” is executed when the value of the encoder output (or DC motor applied current) described above with reference to FIG. 10 becomes smaller than the normal value and exceeds the threshold A. It is controlled to increase the frequency of being performed.
The above-mentioned “normal value R0” is a value of the encoder output (or DC motor applied current) when no follow-up failure of the separation roller 55 has occurred, and has been obtained in advance through experiments, simulations, and the like. Based on this, it is stored in the storage unit of the control unit 70.
The “value R detected by the encoder 90 (or the detection unit 78)” is an average of a plurality of values detected by the encoder 90 (or the detection unit 78) or a standard deviation ( An average value + 3σ) can also be used.

  Here, in this embodiment, instead of the above-mentioned “normal value R0”, “when the feed roller 53 and the separation roller 55 are new, the encoder 90 (or the detection unit 78) has detected. Value "can also be used. That is, the value R detected by the encoder 90 (or the detection unit 78) becomes the value R0 ′ detected by the encoder 90 (or the detection unit 78) when the feed roller 53 and the separation roller 55 are new. In comparison, it is possible to perform control so that the frequency at which the “idle drive mode” is executed increases when the value becomes smaller than a predetermined threshold A ′.

  As described so far, the feeding device 13 in the present embodiment accurately detects the state (forward rotation) of the separation roller 55 that is rotated by the encoder 90 (or the detection unit 78), and the detection result thereof. Since the execution frequency of the idle driving mode is adjusted according to the above, it is possible to reduce a problem that the feed roller 53 and the separation roller 55 are excessively cleaned or insufficiently cleaned. That is, the feed roller 53 and the separation roller 55 are efficiently cleaned at an optimal frequency, and even with the passage of time, there is no feeding failure such as a jam and good feeding performance is maintained.

Here, in the present embodiment, the timing at which the state where the separation roller 55 is rotated by the encoder 90 (or the detection unit 78) as the detection unit is detected as the timing at which the “idle drive mode” is executed. . That is, in this embodiment, every time the “idle drive mode” is executed, the forward rotation of the separation roller 55 is detected by the encoder 90 (or the detection unit 78).
As a result, by detecting the forward rotation of the separation roller 55, it is possible to reduce problems that hinder the printing operation performed by the user in terms of time (less waiting time is likely to occur).

In the present embodiment, when the “idle drive mode” is being executed, the encoder 90 (or the detection unit 78) detects that the state where the separation roller 55 is rotated is worse than a predetermined reference. In addition, the “idle drive mode” is executed again. Specifically, when the detection result R of the encoder 90 (or the detection unit 78) becomes smaller than the normal value R0 by exceeding the threshold B (R0−R> B), the “idle drive” is again performed. "Mode" is running.
Then, even if the “idle drive mode” is executed a predetermined number of times, the encoder 90 (or the detection unit 78) detects that the state where the separation roller 55 is rotated is worse than a predetermined reference (R0−R <B). ) And control to notify that maintenance is necessary.
If the forward rotation performance of the separation roller 55 is not recovered even after repeatedly performing the “idle drive mode”, the feed roller 53 and the separation roller 55 have reached the end of their service life. Become. Therefore, by notifying such a state, the abnormality of the apparatus can be quickly resolved.
The notification that the maintenance is necessary can be displayed on the operation panel 80 of the image forming apparatus 1 and notified to the user, or a service person can be notified via the Internet line connected to the image forming apparatus 1. It is also possible to take a method of informing directly to the (service area).

In this embodiment, when the feed roller 53 and the separation roller 55 are replaced with new ones, the frequency (N value) at which the “idle drive mode” is executed is set to an initial value (default) Value).
By controlling in this way, even after the feed roller 53 and the separation roller 55 are replaced and maintained, the feed roller 53 and the separation roller 55 are efficiently cleaned at an optimum frequency.

  Here, in the present embodiment, at least one piece of information related to the sheet P to be fed, information related to the cumulative number of fed sheets P, and information related to the cumulative operating time of the feeding device 13. Based on the control, the frequency (N value) at which the “idle drive mode” is executed is controlled to be variable.

  “Information relating to the sheet P to be fed” is information such as the paper type, brand, paper thickness, and size of the sheet P accommodated in the feeding device 13 and is input to the operation panel 80 by the user. Detection can be performed based on information about the sheet P. In particular, the paper thickness of the sheet P can be directly detected by a known paper thickness sensor 81 (for example, installed on the entrance guide plate in front of the nip portion). Depending on the paper type, brand, paper thickness, size, etc. of the sheet P, the amount of paper dust, calcium carbonate, etc. adhering to the roller surface of the feed roller 53 and the separation roller 55 also changes. By changing the execution frequency of the mode, the feed roller 53 and the separation roller 55 are efficiently cleaned at a more optimal frequency. Specifically, when a sheet P with a large amount of adhesion such as paper powder or calcium carbonate is used, the N value is set to be small.

The “information relating to the cumulative number of fed sheets P” is the cumulative number of sheets P that have passed through the nip portion since the feed roller 53 and the separation roller 55 are in a new state, and image formation is performed. This can be detected by a counter 82 provided in the apparatus 1.
The “information relating to the accumulated operation time of the feeding device 13” is the accumulated operation time of the DC motor 77 from when the feed roller 53 and the separation roller 55 are in a new state, and is stored in the image forming apparatus 1. This can be detected by an internal timer 83.
When the cumulative number of sheets and the cumulative operation time increase, the irregularities on the roller surfaces of the feed roller 53 and the separation roller 55 are cut and smooth, and foreign matters such as paper dust and calcium carbonate adhering to the roller surface cannot escape into the concave portions. It becomes easy to be scattered on the roller surface, and the decrease in forward rotation of the separation roller 55 is easily promoted. Therefore, by changing the execution frequency of the idle driving mode based on the information, the cleaning of the feed roller 53 and the separation roller 55 is efficiently performed at a more optimal frequency. Specifically, the N value is set to be smaller as the cumulative number of sheets and the accumulated operation time increase.

Here, in the present embodiment, when the number of times the sheet detection sensor 96 detects that the sheet P has not reached within the predetermined time from when the “idle drive mode” was executed last time exceeds the predetermined number. The “idle drive mode” is controlled so that the frequency is increased (the N value is decreased). That is, if the number of times the sheet detection sensor 96 has detected a jam after the previous execution of the idle drive mode is greater than or equal to the predetermined number, the N value is set to be small in the currently active idle drive mode. To do.
This is because when the jam detection is frequently detected by the sheet detection sensor 96, it is highly possible that the transportability of the feed roller 53 is deteriorated in addition to the rotation failure of the separation roller 55. In such a case, by performing the “idle drive mode”, such a problem is easily solved, and it is effective to set the N value small.

Hereinafter, as a summary, the control in the idle drive mode will be described using the control flow of FIG.
As shown in FIG. 8, first, when the idle driving mode is executed in a state where the sheet P is not accommodated in the feeding device 13, the encoder output value R (or DC) is detected by the encoder 90 (or the detection unit 78). Motor applied current value) is acquired (step S1). That is, the forward rotation property of the separation roller 55 is detected by the encoder 90 (or the detection unit 78).
Then, the output value R acquired in step S1 is compared with a predetermined normal value R0, and it is determined whether or not the difference (R0−R) is equal to or greater than the threshold A (step S2). As a result, when it is determined that the difference (R0−R) is not equal to or greater than the threshold value A, it is assumed that the forward rotation performance of the separation roller 55 has hardly deteriorated, and the execution frequency (N value) of the idle driving mode is the default. The value (initial value) is maintained (step S3).
Then, it is determined whether or not the number of jams detected by the sheet detection sensor 96 since the previous execution of the idle driving mode is equal to or less than a predetermined number (step S4). As a result, when it is determined that the number of times of jam detection is less than or equal to a predetermined value, it is assumed that the forward rotation property of the separation roller 55 is deteriorated, and the execution frequency (N value) of the idle driving mode is set small ( In step S9), the next idle driving mode is executed immediately after the Nth sheet end is detected by the end detection sensor 95 based on the setting (step S7).

On the other hand, if it is determined in step S4 that the number of times of jam detection is not less than the predetermined value, information relating to the next sheet P to be fed, information relating to the cumulative number of fed sheets P, feeding Based on the information related to the cumulative operating time of the apparatus 13, it is determined whether or not the conditions are such that the forward rolling property of the separation roller 55 is likely to deteriorate (step S5). As a result, if it is determined that the conditions are such that the forward rotation property of the separation roller 55 is likely to be lowered based on the information, the idle drive mode execution frequency (N value) is set small (step S9). The next idle drive mode is executed immediately after the Nth sheet end is detected by the end detection sensor 95 based on the setting (step S7).
On the other hand, when it is determined in step S5 that the conditions for the forward rotation of the separation roller 55 are not likely to deteriorate, the idle drive mode execution frequency (N value) is maintained at the default value. (Step S6), the next idle driving mode is executed immediately after the Nth sheet end is detected by the end detection sensor 95 based on the setting (Step S7).

On the other hand, if it is determined in step S2 that the difference (R0−R) is greater than or equal to the threshold A, it is further determined whether or not the difference (R0−R) is greater than or equal to the threshold B (step S8). The threshold value B is larger than the threshold value A set in step S2.
As a result, when it is determined that the difference (R0−R) is equal to or greater than the threshold value B, it is necessary to increase the cleaning time of the separation roller 55 and the feed roller 53 to greatly improve the forward rotation property of the separation roller 55. Then, the idle driving mode is executed again within a predetermined number of times (steps S10 and S11). If it is determined in step S11 that the difference (R0−R) is equal to or greater than the threshold B even after the idling drive mode is performed a predetermined number of times, it is assumed that maintenance of the separation roller 55 and the feed roller 53 is necessary. Then, the idle drive mode is stopped (step S12), and notification that maintenance is required is made (step S13). Thereafter, after confirming that the maintenance of the separation roller 55 and the feed roller 53 has been performed, the N value is returned to the default value (step S14).
If it is determined in step S8 that the difference (R0-R) is not equal to or greater than the threshold value B, the separation roller 55 and the feed roller 53 have been cleaned to some extent, but the forward rotation of the separation roller 55 is reduced. It is assumed that the frequency (N value) of the idle driving mode is set small (step S9), and the next empty state is detected immediately after the Nth sheet end is detected by the end detection sensor 95 based on the setting. The drive mode is executed (step S7).

As described above, in the feeding device 13 according to the present embodiment, the separation roller 55 is accompanied by the rotation of the feed roller 53 in a state where the sheet P is not sandwiched in the nip portion between the feed roller 53 and the separation roller 55. An encoder 90 (or detection unit 78) is provided as detection means for detecting the rotating state. When the encoder 90 (or the detection unit 78) detects that the state where the separation roller 55 is rotated is poor, the sheet P is compared with the case where the state where the separation roller 55 is detected is good. The “idle drive mode” that is performed without feeding is controlled so as to increase the frequency of execution.
Thereby, the cleaning of the feed roller 53 and the separation roller 55 is efficiently performed at an optimum frequency, and good feeding performance can be maintained over time.

In the present embodiment, the present invention is applied to the feeding device 13 installed in the monochrome image forming apparatus 1. However, the present invention is naturally applied to the feeding device installed in the color image forming apparatus. The present invention can be applied.
Further, in the present embodiment, the present invention is applied to the feeding device 13 installed in the electrophotographic image forming apparatus 1, but the application of the present invention is not limited to this, and other methods. The present invention can also be applied to a feeding apparatus installed in an image forming apparatus (for example, an inkjet image forming apparatus or a stencil printing machine).
Even in such cases, the same effects as those of the present embodiment can be obtained.

Further, in the present embodiment, the present invention is applied to the feeding device 13 installed inside the image forming apparatus 1, but manual feeding that is installed so as to be exposed to the outside of the image forming apparatus 1. The present invention can also be applied to the feeding device 16, and the present invention can also be applied to the document conveying unit 10 (automatic document conveying device) as a feeding device.
In the present embodiment, the present invention is applied to the FRR paper feed type feeding device 13 in which the separation roller 55 is connected to the drive source (DC motor 77) via the torque limiter 56. The present invention can also be applied to an RF paper feed apparatus (for example, disclosed in Patent Document 1) in which a separation roller having no roller is installed via a torque limiter. .
Even in such cases, the same effects as those of the present embodiment can be obtained.

  It should be noted that the present invention is not limited to the present embodiment, and it is obvious that the present embodiment can be modified as appropriate within the scope of the technical idea of the present invention, other than suggested in the present embodiment. is there. In addition, the number, position, shape, and the like of the constituent members are not limited to the present embodiment, and the number, position, shape, and the like suitable for implementing the present invention can be achieved.

  In the present specification and the like, “sheet” is defined to include all sheet-like members such as coated paper, label paper, OHP sheet, and film in addition to normal paper (paper).

1 image forming apparatus (image forming apparatus main body),
13 Feeding device,
52 Feeding mechanism (feeding means),
53 Feed roller,
54 Pickup roller,
55 Separation roller (reverse roller),
56 Torque limiter,
77 DC motor (drive source),
78 detector (detector),
90 Encoder (detection means),
91 Photosensor,
92 Detected plate,
95 End detection sensor,
96 Sheet detection sensor (sheet detection means),
P sheet.

JP 2007-119189 A JP 2002-255383 A JP 2002-193466 A

Claims (11)

A feed roller that rotates along the feeding direction of the sheet and feeds the sheet in the feeding direction;
It is installed so as to form a nip portion with the feed roller, and when one sheet is sandwiched in the nip portion and when no sheet is sandwiched in the nip portion, the feeding direction When a plurality of sheets are sandwiched in the nip portion, only the uppermost sheet among the plurality of sheets is fed in the feeding direction along the rotation of the feed roller. A separation roller for separating the lower sheet from the uppermost sheet,
When the feed roller rotates along the feeding direction with no sheet held in the nip portion, the separation roller rotates along the feeding direction as the feed roller rotates. Detection means for detecting the state;
With
An idle driving mode in which the feed roller is rotated along the feeding direction without feeding a sheet is executed at a predetermined timing,
The idle drive mode is executed when the detection unit detects that the state where the separation roller is rotated is poor as compared with the case where the detection unit detects that the state where the separation roller is rotated is good. The feeding device is controlled so that the frequency of the feeding is increased. Provided with an end detection sensor that detects a state in which all of the sheets stored in the feeding device are gone,
The idle driving mode is executed when the number of times detected by the end detection sensor reaches N times,
When the detection means detects that the state where the separation roller is rotated is poor, the N times is less than the case where the detection means detects that the separation roller is rotated. The feeding device according to claim 1, wherein the feeding device is controlled to become.   The feeding device according to claim 1, wherein the detection unit is an encoder that detects a rotation speed of the separation roller. A DC motor that rotationally drives the feed roller and the separation roller;
When one sheet is sandwiched in the nip portion and when no sheet is sandwiched in the nip portion, the drive transmission from the motor to the separation roller is cut off, and a plurality of sheets are placed in the nip portion. A torque limiter that transmits drive from the motor to the separation roller when the sheet is sandwiched;
With
The feeding device according to claim 1, wherein the detection unit is a unit that detects a current or a voltage applied to the DC motor.   The value detected by the detection means exceeds a predetermined threshold value compared to a value at normal time or a value detected by the detection means when the feed roller and the separation roller are new. 5. The feeding device according to claim 3, wherein the feeding device is controlled so that the frequency at which the idle driving mode is executed increases when the idle driving mode is reduced.   The feeding according to any one of claims 1 to 5, wherein the timing at which the state where the separation roller is rotated is detected by the detection means is a timing at which the idle driving mode is executed. apparatus.   When the idle driving mode is being executed, the idle driving mode is executed again when the detection means detects that the state where the separating roller is rotated is worse than a predetermined reference, and the idle driving mode is executed. 7. The apparatus according to claim 6, wherein when the state where the separating roller is rotated by the detecting means is detected to be worse than the predetermined reference even if the predetermined number of times is executed, a notification is made that maintenance is necessary. The feeding device described.   The idle driving mode is executed based on at least one of information relating to the fed sheets, information relating to the cumulative number of fed sheets, and information relating to the cumulative operating time of the feeding device. The feeding device according to any one of claims 1 to 7, wherein the frequency of the feeding is variable. A sheet detection sensor that detects a state in which a sheet that should reach a predetermined position on the downstream side in the feeding direction with respect to the nip portion has not reached a predetermined time;
When the number of times that the state that has not been reached within the predetermined time is detected by the sheet detection sensor from when the idle driving mode was executed last time exceeds the predetermined number of times, the idle driving mode is frequently executed. It controls so that it may become. The feeding apparatus in any one of Claims 1-8 characterized by the above-mentioned.   The frequency at which the idle driving mode is executed is returned to a preset initial value when the feed roller and the separation roller are replaced with new ones. The feeding device according to any one of the above.   An image forming apparatus comprising the feeding device according to claim 1.

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