JP6880486B2 - Feeding device and image forming device - Google Patents

Description

The present invention relates to a feeding device for feeding sheets, and an image forming device such as a copying machine, a printer, a facsimile, or a multifunction device or a printing machine thereof provided with the feeding device.

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. A FRR paper feed system connected to a source, an RF paper feed system in which a separation roller having no drive source is installed via a torque limiter, and the like are widely known (for example, Patent Document 1). See ~ 3.).

Specifically, such a feeding device includes a feed roller that conveys the sheet housed in the device in the feeding direction, and a feed roller that is configured to be detachable from the sheet housed in the device. It is composed of a pickup roller that conveys the sheet toward the position of the above, a separation roller that presses against the feed roller to form a nip, and prevents double feeding of the sheet.
Then, when one sheet is sandwiched between the nip portions, the separation roller is driven to rotate along the feeding direction of the sheet, and the sheet is fed by the feed roller in the desired feeding direction. On the other hand, when a plurality of sheets are sandwiched between the nip portions, the lower sheet is sent to the uppermost sheet by the separation roller so that only the uppermost sheet is fed along the rotation of the feed roller. Is separated.

On the other hand, Patent Documents 1 and 2 describe a technique for executing a "cleaning mode" in which the feed roller is rotated with the separation roller pressed against the feed roller at a predetermined timing in order to clean the surface of the feed roller. It is disclosed.
Further, Patent Document 3 discloses a technique for recovering the frictional force of the pickup roller by bringing the pickup roller into contact with the frictional force recovery member while rotationally driving the pickup roller each time the sheet housed in the paper feed cassette is exhausted. ing.

In the conventional feeding device, the feed roller is rotated with the separation roller pressed against the feed roller at a predetermined timing, so that foreign substances such as paper dust and calcium carbonate adhering to the feed roller and the separation roller are removed. Therefore, the effect of maintaining good feeding performance can be expected to some extent.
However, in the conventional feeding device, the feed roller and the separation roller are excessively cleaned or the cleaning is insufficient. That is, the feed rollers and separation rollers were not cleaned efficiently at the optimum frequency.

The present invention has been made to solve the above-mentioned problems, and the feed roller and the separation roller are efficiently cleaned at the optimum frequency, and good feeding performance is maintained over time. , A feeding device, and an image forming device.

The feeding device in the present invention is installed so as to form a nip portion between a feed roller that rotates along the feeding direction of the sheet and feeds the sheet in the feeding direction and the feed roller. Then, when one sheet is sandwiched between the nip portions and when the sheet is not sandwiched between the nip portions, the sheets rotate along the feeding direction, and a plurality of sheets are sandwiched between the nip portions. When the sheets are sandwiched, the lower sheet is set with respect to the uppermost sheet so that only the uppermost sheet out of the plurality of sheets is fed in the feeding direction along the rotation of the feed roller. When the separation roller to be separated and the feed roller rotate along the feeding direction in a state where the sheet is not sandwiched between the nip portions, the separation roller moves in the feeding direction as the feed roller rotates. and a detection means for detecting a state rotated together along the, air drive mode for rotating the feed roller without feeding sheets along said feed direction is performed at a predetermined timing, the The value detected by the detection means is smaller than the normal value or the value detected by the detection means when the feed roller and the separation roller are new, exceeding a predetermined threshold value. When this happens, the air drive mode is controlled so as to be executed more frequently.

According to the present invention, there is provided a feeding device and an image forming device in which the feed roller and the separation roller are efficiently cleaned at an optimum frequency and good feeding performance is maintained over time. be able to.

It is an overall block diagram which shows the image forming apparatus in embodiment of this invention. It is a schematic block diagram which shows the feeding device. It is a schematic block diagram which shows the drive system of a feeding device. It is the schematic which shows the operation of the contact / separation mechanism of a pickup roller in a feeding device. It is the schematic which shows the operation when a plurality of sheets are sandwiched in a nip part in a feeding device. It is a graph which shows the change of the motor voltage when a plurality of sheets are sandwiched in a nip part in a feeding device. It is a figure which shows the state which the empty drive mode is executed in the feeding device. It is a flowchart which shows the control in the air drive mode. It is a figure which shows the state which the separation roller has a rotation failure. There are (A) a graph showing a change in the encoder output and (B) a graph showing a change in the applied current of the DC motor when the separation roller has a rotation defect.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In each figure, the same or corresponding parts are designated by the same reference numerals, and the duplicated description thereof will be appropriately simplified or omitted.

First, FIG. 1 describes the overall configuration and operation of the image forming apparatus 1.
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 photoconductor that emits exposure light L based on the image information read by the document reading unit 2. The exposure unit 4 that irradiates the drum 5 is an image forming unit that forms a toner image (image) on the photoconductor drum 5, and the 7 is an image forming unit that forms a toner image (image) on the photoconductor drum 5 on a sheet P (recording medium). The transfer unit (image forming unit) to be transferred, 10 is a document transporting unit (automatic document transporting device) that transports the set document D to the document reading unit 2, and 12 and 13 are sheets P housed in the paper feed cassette. A feeding device for feeding, 16 is a manual feeding device for feeding a sheet P manually set by the user, 17 is a registration roller (timing roller) for transporting the sheet P toward the transfer unit 7, and 20 is a sheet P. A fixing device for fixing the toner image (unfixed image) carried on the top, 21 is a fixing roller installed in the fixing device 20, 22 is a pressure roller installed in the fixing device 20, and 31 is discharged from the device main body 1. The output trays 42 and 43 on which the paper sheet P is loaded are mounting portions (elevating plates) configured to be able to move up and down in the feeding devices 12 and 13, and 52 are the feeding devices 12, 13 and 16. A feeding mechanism as a feeding means installed in the 80 is an operation panel (operation display) installed on the exterior of the device main body 1 for displaying or operating the image forming apparatus 1. Panel), is shown.

With reference to FIG. 1, the operation of the image forming apparatus main body 1 at the time of normal image forming will be described.
First, the document D is conveyed (fed) from the document table in the direction of the arrow in the drawing by the transfer roller of the document transfer 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, the exposure light L such as a laser beam based on the image information of the electric signal is emitted from the exposure unit 3 toward the photoconductor drum 5 of the image forming unit 4.

On the other hand, in the image forming unit 4, the photoconductor drum 5 is rotated in the clockwise direction of FIG. 1, and undergoes a predetermined image forming process (charging step, exposure step, developing step), and image information is displayed on the photoconductor drum 5. An image (toner image) corresponding to is formed.
After that, the image formed on the photoconductor drum 5 is transferred to the sheet P conveyed by the resist roller 17 by the transfer unit 7 as the image forming unit.

On the other hand, the sheet P transported 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 of the sheets P housed in the feeding device 13 is fed by the feeding mechanism 52 and transported toward the transport path K. After that, the sheet P passes through the transport path K in which the plurality of transport rollers are arranged and reaches the position of the resist roller 17.
When the feeding device 16 (manual feeding device) installed on the side of the device main body 1 is selected, the sheet placed on the mounting portion (manual feeding tray) of the feeding device 16 by the user. P (when a plurality of sheets P are loaded, the uppermost sheet P) is fed toward the transport path by the feeding mechanism 52 (feeding means) and reaches the position of the resist roller 17. It will be.

The sheet P that has reached the position of the resist 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 photoconductor drum 5.
Then, the sheet P after the transfer step reaches the fixing device 20 via the transport path after passing through the position of the transfer unit 7. 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. (It is a fixing process). The sheet P after the fixing step in which the toner image is fixed is sent out from between the fixing roller 21 and the pressure roller 22 (which is a fixing nip), and then discharged from the image forming apparatus main body 1 to output an image. Will be loaded on the output tray 31.
In this way, 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. 2 to 6 and the like.
Of the plurality of feeding devices 12 and 13 inscribed in the device main body 1, the lower feeding device 13 will be described below, but the upper feeding device 12 is also in the lower row except that the installation position is different. Since the configuration is almost the same as that of the feeding device 13 of the above, the description thereof will be omitted.

With reference to FIG. 2 and the like, the feeding device 13 is supplied with a mounting portion 43 (elevating plate) formed so that a plurality of sheets P can be loaded, and a seat P mounted on the mounting portion 43. A feeding mechanism 52, etc. as a feeding means for feeding is installed.
The mounting portion 43 is configured to move up and down by rotating in the forward and reverse directions about the rotation center axis 43a (see FIG. 1).
Further, referring to FIGS. 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, and an encoder. It is composed of 90 (detection means), contact / detachment mechanisms 58, 72, 73, and the like.

The feed roller 53 is installed on the tip side in the feeding direction (in the direction of the white arrow in FIG. 2) with respect to the sheet P mounted on the mounting portion 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 (rotation in the counterclockwise direction in FIG. 2), and the sheet P is fed in the feeding direction indicated by the one-point chain arrow.
With reference to FIG. 3, the feed roller 53 has two-stage gears 65 and 66 installed on the shaft portion thereof. 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 pulleys 63 of the pulleys / two-stage gears 62 to 64, and the lower gear 62, and feeds. The roller 53 is rotationally driven in the counterclockwise direction of FIG.

The pickup roller 54 rotates counterclockwise in FIG. 2 along the traveling direction in a state of being in contact with the surface (upper surface) of the seat P mounted on the mounting portion 43, and feeds the seat P. It is conveyed toward the position of the roller 53.
With reference to FIG. 3, a gear 68 is installed on the shaft of the pickup roller 54. Then, the drive is transmitted from the DC motor 77 to the gear 68 via the motor pulley 60, the timing belt 61, the pulleys / two-stage gears 62 to 64, the two-stage gears 65 and 66, and the idler gear 67, and the pickup roller 54 is shown in FIG. It will be driven to rotate counterclockwise.

Further, the pickup roller 54 is configured to be detachable from the seat P (the uppermost seat P1) mounted on the mounting portion 43. That is, the pickup roller 54 has a retracted position (the position shown in FIG. 4B) that does not abut against the sheet P mounted on the mounting portion 43 and a contact position (FIG. 2) that abuts the pickup roller 54. , The position shown in FIG. 4 (A)) and is formed so as to be movable.
For details, with reference to FIG. 4 and the like, the pickup roller 54 is rotatably held by the arm 58. The arm 58 is rotatably held by the rotation shaft of the feed roller 53. The protruding portion 58a of the arm 58 is provided with a spring 73 (a urging member) that urges the pickup roller 54 to move to the retracted position, or a pickup roller 54 at a contact position so as to resist the urging force of the spring 73. A moving solenoid 72 is connected. Then, when the pickup roller 54 moves to the contact position as shown in FIG. 4A when the solenoid 72 is turned on under the control of the control unit 70, 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 the arm is maintained in a meshed state with the gear 68 of the pickup roller 54 and a meshed 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 between the separation roller 55 and the feed roller 53.
Then, the separation roller 55 rotates along the feeding direction when one sheet P is sandwiched between the nip portions and when the sheet P is not sandwiched between the nip portions (FIG. 2). In the direction of the dashed arrow, it rotates clockwise).
On the other hand, in the separation roller 55, when a plurality of sheets P are sandwiched between the nip portions, the uppermost sheet P1 of the plurality of sheets P moves in the feeding direction along 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 between the nip portions of the separation roller 55, the uppermost sheet P1 of the plurality of sheets P is fed in the feeding direction along the rotation of the feed roller 53. It is fed and rotates along the opposite direction so that the lower sheet P2 is conveyed in the direction opposite to the feeding direction (in the direction of the solid arrow in FIG. 2, and rotates in the counterclockwise direction). ).

For details, with reference to FIG. 3, the separation roller 55 has a gear 69, a torque limiter 56, and a detected plate 92 installed on 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 pulleys 63 of the pulleys / two-stage gears 62 to 64, and the upper gear 64, and the drive is further transmitted via the torque limiter 56. It will be transmitted to or blocked by the separation roller 55.
The torque limiter 56 is configured such that when a rotational load exceeding a predetermined value is applied to the separation roller 55, the separation roller 55 idles relative to the torque limiter 56.

Specifically, in the torque limiter 56, when one sheet P is sandwiched between the nip portion (the contact portion between the feed roller 53 and the separation roller 55) and when the sheet P is sandwiched between the nip portions. When not present, 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 in a state of idling with respect to the torque limiter 56, and is rotated (driven rotation) in the clockwise direction of FIG. 2 along the rotation of the feed roller 53.
On the other hand, when a plurality of sheets P are sandwiched between the nip portions, the torque limiter 56 is separated from the DC motor 77 because the rotational load applied to the separation roller 55 is relatively small due to the slip between the sheets P. The drive is transmitted to the roller 55. As a result, the separation roller 55 is rotationally driven in the counterclockwise direction of FIG. 2, and among the plurality of sheets P sandwiched between the nip portions, the lower sheet except the uppermost sheet P1 is in the opposite direction (FIG. 5 (FIG. 5). It is conveyed in the direction of the black arrow in B) and returned to the mounting portion 43.
With such a configuration, one sheet P is fed in the feeding direction (conveying direction) without the sheet P being double-fed from the nip portion of 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 in the axial direction. It was formed by dividing it into a plurality of parts. Further, the feed roller 53, the pickup roller 54, and the separation roller 55 are each formed so that the roller portion is removable (replaceable) with respect to the shaft portion, so that the maintenance of the roller portion can be easily performed. There is.

Further, as described with reference to FIG. 3, the DC motor 77 functions as a drive source (motor) for rotationally driving 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 rotation speed of the motor shaft becomes a predetermined value. Specifically, the PWM control by the control unit 70 adjusts the current (or voltage) applied to the DC motor 77 so that the rotation speed of the DC motor 77 becomes constant regardless of the load fluctuation. (See FIG. 6). Specifically, when the load applied to the DC motor 77 is large, the current (or voltage) applied to the DC motor 77 is adjusted to be large, and when the load applied to the DC motor 77 is small, the current (or voltage) is applied to the DC motor 77. The current (or voltage) is adjusted so as to be small, and the rotation speed of the DC motor 77 is made constant.
This enables stable paper feeding by the feeding mechanism 52.

Here, referring to FIG. 3, the feeding device 13 in the present embodiment is provided with an encoder 90 that detects the rotation speed and the rotation direction of the separation roller 55.
The encoder 90 includes a detected plate 92 that rotates together with the separation roller 55 (a plurality of holes are formed in the circumferential direction at regular intervals on the outer peripheral portion thereof) and a photo that detects the holes of the detected plate 92. It is composed of a sensor 91 and. Then, in the present embodiment, the execution frequency of the "empty drive mode" is changed by the change in the rotation speed of the separation roller 55 when the separation roller 55 is rotated, which is detected by the encoder 90. This will be described in detail later. To do.

Here, the feeding device 13 in the present embodiment is a sheet P loaded on the mounting portion 43 so that the pickup roller 54 can come into contact with the uppermost sheet P loaded on the mounting portion 43. Depending on the number of sheets, the mounting portion 43 moves up and down in the vertical direction. Then, the pickup roller 54 is lowered to a position where it comes into contact with the upper surface of the seat P mounted on the mounting portion 43 whose vertical position is adjusted, and then the seat P is fed.
Further, an inlet guide plate is installed between the mounting portion 43 and the nip portion between the feed roller 53 and the separation roller 55.
Further, the feeding device 13 in the present embodiment is provided with a side fence that regulates the position of the sheet P mounted on the mounting portion 43 in the width direction (the direction perpendicular to the paper surface in FIG. 2). ing. The side fences are installed at both ends in the width direction so as to sandwich the seat P, and are configured to be movable in the width direction according to the size of the seat P in the width direction by a manual movement mechanism.
Further, the feeding device 13 in the present embodiment is provided with an end fence that regulates the position of the seat P mounted on the mounting portion 43 in the feeding direction (the left-right direction in FIG. 2). ing. The end fence is installed so as to abut on the rear end of the seat P in the feeding direction, and is configured to be movable in the feeding direction according to the size of the seat P in the feeding direction by a manual moving mechanism.

In the feeding device 13 configured in this way, when the seat P is not set in the mounting unit 43, that state is detected by the end detection sensor 95, and the pickup roller is controlled by the solenoid 72 by the control unit 70. 54 is in a state of being retracted to the retracted position (the position shown in FIG. 4B).
Then, when the seat P is set in the mounting portion 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 by the control of the solenoid 72 by the control unit 70 (FIG. 4 (FIG. 4). It is moved toward the position shown in A)).
Then, as shown in FIG. 2, the counterclockwise rotational drive of the pickup roller 54 is started in a state where the pickup roller 54 is in contact with the upper surface of the uppermost sheet P mounted on the mounting portion 43. 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 mounted on the mounting portion 43 by the pickup roller 54 is conveyed toward the nip portion of 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 portion.
Further, when all the seats P mounted on the mounting unit 43 are fed and the seats P are not set on the mounting unit 43, the state is detected by the end detection sensor 95 and the control unit The pickup roller 54 is moved to the retracted position again by the control of the solenoid 72 by 70 (the state shown in FIG. 4B).

FIG. 5 shows an example of the operation of the feeding device 13, and is a schematic view showing the operation when a plurality of sheets P are sandwiched between the nip portions.
First, as shown in FIG. 5A, when the seat P is set on the mounting portion 43, the mounting portion 43 rises to an optimum position, and then the pickup roller 54 is controlled by the solenoid 72 by the control unit 70. Is moved from the retracted position to the contact position (the position shown in FIG. 5A). Then, as shown in FIG. 5A, the rotation drive of the pickup roller 54 in the counterclockwise direction is started in a state where the pickup roller 54 is in contact with the upper surface of the uppermost sheet P1 mounted on the mounting portion 43. Then, the sheets P1 and P2 mounted on the mounting 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 the 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 in an idling state, and the separation roller 55 is rotating clockwise.

Then, as shown in FIG. 5B, when the two heavy-running sheets P1 and P2 are conveyed to the nip portion, the pickup roller 54 moves to the retracted position again. At this time, the two sheets P1 and P2 are sandwiched between the nip portions, so that the torque limiter 56 is connected and the separation roller 55 starts rotating counterclockwise.
Then, as the separation roller 55 rotates counterclockwise, as shown in FIG. 5C, the lower sheet P2 is conveyed in the direction of the black arrow along the rotation of the separation roller 55 (mounting portion). It is returned toward 43.). Further, the upper sheet P1 (the uppermost sheet P1) is conveyed in the direction of the white arrow along the rotation of the feed roller 53 (is conveyed toward the transfer path of the image forming apparatus main body 1).
Then, as shown in FIG. 5 (D), when the lower sheet P2 returned toward the mounting portion 43 by the separation roller 55 passes through the nip portion, the torque limiter 56 is in a state of idling again and separated. The roller 55 rotates clockwise again.
When one sheet P is sandwiched between the nip portions without sandwiching the plurality of sheets P from the state of FIG. 5 (A), the separation roller 55 is used as shown in FIGS. 5 (B) and 5 (C). As shown in FIG. 5 (D), the uppermost sheet P1 is conveyed in the direction of the white arrow without rotating counterclockwise while rotating clockwise.

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

Specifically, as shown in FIG. 7, when 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), the feed roller 53 rotates. When the separator 90 (detecting means) detects that the rotation speed of the separation roller 55 is lower than that in the normal state while the separation roller 55 is rotating (driven rotation), the separation roller 55 is rotated. It is judged that the condition (degree of traveling) has deteriorated and the vehicle has not been circulated well.
When the separation roller 55 has a poor rotation, the output of the encoder 90 (photosensor 91) changes as shown in FIG. 10A. That is, with respect to the "normal" encoder output cycle H0 in which the separation roller 55 rotates at substantially the same speed as the feed roller 53 without slipping, the separation roller 55 slips and the rotation speed is lower than in the normal state. The encoder output cycle H1 at the time of "improper rotation" becomes longer according to the degree.

Further, as a mode of poor rotation of the separation roller 55 that occurs in the situation of rotating the separation roller 55, first, as shown in FIG. 9A, there is a state in which the separation roller 55 rotates at a lower speed than in the normal state. If the condition is further deteriorated, the separation roller 55 may stop rotating as shown in FIG. 9B, or the separation roller 55 may rotate in the reverse direction as shown in FIG. 9C. Become.
In any of the modes, if the separation roller 55 has a poor rotation, 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. 9 shows. A phenomenon occurs in which the tip of the sheet P collides with the entrance of the enclosed nip portion, so that the sheet P is not smoothly delivered from the nip portion or the sheet P is jammed (paper jam) at the nip portion. Become.

In such a poor rotation of the separation roller 55, foreign matter such as paper dust and calcium carbonate generated from the sheet P adheres to the roller surface (formed of the rubber material) of the separation roller 55 and the feed roller 53. , It is caused by a decrease in the frictional force on the roller surface.

Then, the poor rotation of the separation roller 55 is caused by the sheet detection sensor 96 that detects a state in which the sheet P, which 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 within a predetermined time. It is an optical sensor that optically detects the passing sheet P, and can also be detected to some extent by (see FIGS. 2 and 9). That is, the sheet P is not smoothly delivered from the nip portion and the time to reach the position of the sheet detection sensor 96 is delayed, or the sheet P is jammed (paper jam) at the nip portion and the sheet detection sensor 96 When the position is not reached, the state can be detected by the sheet detection sensor 96, and the state in which the separation roller 55 has a poor rotation can be grasped.

However, when foreign matter is attached to the roller surface of the separation roller 55 or the feed roller 53, the frictional force on the roller surface is not so reduced, and the rotation speed of the separation roller 55 is not so low. There is almost no delay in 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 separation roller 55 has a poor rotation. That is, the sheet detection sensor 96 cannot accurately detect poor rotation of the separation roller 55 (dirt on the roller surface of the separation roller 55 and the feed roller 53).
On the other hand, in the present embodiment, since the encoder 90 (detection means) directly detects the rotating state (degree of rotation) of the separation roller 55, the separation roller 55 is slightly defective in rotation. Even (dirt on the roller surface of the separation roller 55 and the feed roller 53) can be detected with high accuracy.

Hereinafter, the description will be further supplemented.
A paper feeding method in which the separation roller 55 is rotated with respect to the feed roller 53 via a torque limiter 56 to separate and convey the sheet P into one sheet (the FRR paper feeding method as in the present embodiment, or the FRR paper feeding method The feeding device of the RF paper feeding method described in Patent Document 1) is a feeding device of the separating roller 55 even though the frictional force between the feed roller 53 and the separating roller 55 with respect to the sheet P is not so reduced. It may reduce the ability to carry around.
This is because the unevenness of the rubber roller surface of the feed roller 53 and the separation roller 55 is reduced, and if a particle component such as calcium carbonate is present in a state of floating between the rubber rollers, the particle component becomes the unevenness of the sheet P. This is because it may be hidden. In such a state, even though the transport 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 by the recesses on the surface of the rubber rollers and are between the rollers. The rubber rollers will rotate at the same time, and the carrying force (coefficient of friction) between the rubber rollers will decrease, resulting in a decrease in the ability to carry around.
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 sheet tip at the time of feeding does not become an abnormal delay state. In addition, it is not possible to detect a poor rotation of the separation roller 55.
On the other hand, in the present embodiment, as described above, the encoder 90 (detection means) can accurately detect the poor rotation of the separation roller 55.

In the specification of the present application and the like, the state in which the separation roller 55 is rotated (degree of rotation) detected by the detection means is appropriately referred to as "forward rotation" or "rotation". I'll call you. The forward rotation (rotational property) of the separation roller 55 directly or indirectly detects 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 by.

Here, in the present embodiment, the encoder 90 is used as a detection means for detecting the forward rotation (carrying property) of the separation roller 55.
On the other hand, as a detection means for detecting the forward rotation of the separation roller 55, a detection unit 78 (see FIG. 2), which is a means for detecting the current (or voltage) applied to the DC motor 77, is used. It can also be used.
Specifically, the detection unit 78 (detection means) detects a change in the current (or voltage) applied to the DC motor 77 as described above with reference to FIG. 6, thereby applying a load to the DC motor 77. Detects changes in torque. As the detection unit 78, a current measuring device (or voltage measuring device) that detects a change in the current (or voltage) applied to the DC motor 77 can be used.

Specifically, as shown in FIG. 7, when 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), the feed roller 53 rotates. When the separation roller 55 is rotating (driven rotation) and the detection unit 78 (detection means) detects that the current applied to the DC motor 77 is lower than that in the normal state, the separation roller 55 It is judged that the condition of the caring around (the degree of the caring around) has deteriorated and the car is not being carried around well.
When the separation roller 55 has a poor rotation as described above, the DC motor applied current changes as shown in FIG. 10 (B). That is, with respect to the "normal" DC motor applied current in which the separation roller 55 rotates at substantially the same speed as the feed roller 53 without slipping, the separation roller 55 slips and the rotation speed is lower than in the normal state. The applied current of the DC motor at the time of poor rotation becomes lower according to the degree.
Even when the detection unit 78 is used as the detection means in this way, it is possible to accurately detect the poor rotation of the separation roller 55 (dirt on the roller surface of the separation roller 55 and the feed roller 53).

Here, in the present embodiment, as shown in FIG. 7, the "empty drive mode" in which the feed roller 53 is rotated along the feeding direction without feeding the seat P is executed at a predetermined timing. .. In this "idle drive mode", the DC motor 77 is operated to idlely rotate the feed roller 53 and the separation roller 55 without performing the feeding operation of the seat P. At this time, the feed roller 53 rotates counterclockwise in FIG. 7, and the separation roller 55 rotates (rotates) in the clockwise direction in FIG. 7.
Then, by performing the "empty drive mode" in this way, the roller surfaces of the separation roller 55 and the feed roller 53 are directly rubbed against each other, and foreign substances such as paper dust and calcium carbonate adhering to the roller surfaces are removed. It will be removed so that it can be scraped off. That is, the "empty drive mode" is performed to clean the roller surfaces of the separation roller 55 and the feed roller 53. Then, by performing the "empty drive mode", the friction coefficient of the roller surfaces of the separation roller 55 and the feed roller 53 is restored, and the forward rotation (carrying property) of the separation roller 55 is also restored to the original state. It will be. Therefore, by performing the "empty drive mode", the poor rotation of the separation roller 55 can be reduced.

Then, in the present embodiment, when the encoder 90 (or the detection unit 78) as the detection means detects that the separation roller 55 is in a bad state of being carried around, the encoder 90 (or the detection unit 78) separates the separation roller 55. It is controlled so that the "empty drive mode" is executed more frequently than when it is detected that the roller 55 is in a good state of being carried around.

Specifically, as described above, the mounting portion 43 of the feeding device 13 is provided with an end detection sensor 95 that detects a state in which all the sheets P housed in the feeding device 13 are exhausted. There is.
Then, when the number of times detected by the end detection sensor 95 reaches N times (a value that is variable in terms of control and is appropriately referred to as an "N value"), the "empty drive mode" is executed. It is controlled like this. That is, immediately after the seat P is emptied in the feeding device 13 and the seat P is newly replenished N-1 times, and the state in which the seat P is emptied is detected at the Nth time is detected. , "Empty drive mode" will be executed. In this way, by executing the empty drive mode immediately after the sheet P in the feeding device 13 is in the end state, it is less likely to interfere with the printing operation performed by the user in terms of time (waiting time is less likely to occur).
Then, when the encoder 90 (or the detection unit 78) detects that the separation roller 55 is in a bad state of being carried around, the encoder 90 (or the detection unit 78) is in a state of being in a good state of being carried around by the separation roller 55. The above-mentioned N times (N value) is controlled to be a smaller value than when it is detected. That is, when it is determined that the forward rotation of the separation roller 55 has decreased, the N times (N value) are reduced and the idle drive mode is executed more frequently, so that the separation roller 55 and the feed roller 53 Cleaning will be done frequently.

More specifically, when the value R detected by the encoder 90 (or the detection unit 78) becomes smaller than the normal value R0 by exceeding a predetermined threshold value A (R0-R> A). ), It is controlled so that the "empty drive mode" is executed more frequently. That is, when the value of the encoder output (or DC motor applied current) described above with reference to FIG. 10 becomes smaller than the threshold value A as compared with the normal state, the "empty drive mode" is executed. It is controlled so that it is performed more frequently.
The above-mentioned "normal value R0" is a value of the encoder output (or DC motor applied current) when the separation roller 55 does not have a poor rotation, and is based on the results of experiments and simulations in advance. Based on this, it is stored in the storage unit of the control unit 70.
Further, the "value R detected by the encoder 90 (or the detection unit 78)" is an average of a plurality of values detected a plurality of times by the encoder 90 (or the detection unit 78) or a standard deviation (standard deviation). An average value + 3σ) can also be used.

Here, in the present embodiment, instead of the above-mentioned "normal value R0", "when the feed roller 53 and the separation roller 55 are new, they are detected by the encoder 90 (or the detection unit 78). You can also use "value". 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 also possible to control so that the "empty drive mode" is executed more frequently when the value exceeds the predetermined threshold value A'and becomes smaller.

As described above, the feeding device 13 in the present embodiment accurately detects the rotating state (forward rotation) of the separation roller 55 by the encoder 90 (or the detection unit 78), and the detection result is obtained. Since the execution frequency of the idle drive mode is adjusted according to the above, it is possible to reduce problems such as excessive cleaning of the feed roller 53 and the separation roller 55 or insufficient cleaning. That is, the feed roller 53 and the separation roller 55 are efficiently cleaned at an optimum frequency, and good feeding performance is maintained without feeding defects such as jams even over time.

Here, in the present embodiment, the timing at which the encoder 90 (or the detection unit 78) as the detection means detects the state in which the separation roller 55 is rotated is the timing at which the "empty drive mode" is executed. .. That is, in the present embodiment, the forward rotation of the separation roller 55 is detected by the encoder 90 (or the detection unit 78) each time the "idle drive mode" is executed.
As a result, by detecting the forward rotation of the separation roller 55, it is possible to reduce the problem of timely hindering the printing operation performed by the user (waiting time is less likely to occur).

Further, in the present embodiment, when the encoder 90 (or the detection unit 78) detects that the state in which the separation roller 55 is carried around is worse than a predetermined reference while the "empty drive mode" is being executed. In addition, the "empty drive mode" is executed again. Specifically, when the detection result R of the encoder 90 (or the detection unit 78) exceeds the threshold value B and becomes smaller than the normal value R0 (R0-R> B), the "empty drive" is performed again. The mode is running.
Then, when the encoder 90 (or the detection unit 78) detects that the state in which the separation roller 55 is carried around is worse than the predetermined reference even if the "empty drive mode" is executed a predetermined number of times (R0-R <B). ), It is controlled to notify that maintenance is required.
If the forward rotation of the separation roller 55 is not restored even after repeating the "idle drive mode", maintenance such as replacing the feed roller 53 or separation roller 55 has reached the end of its life is required. Become. Therefore, by notifying such a state, the abnormality of the device can be quickly resolved.
The notification that maintenance is required can be displayed on the operation panel 80 of the image forming apparatus 1 to notify the user, or a serviceman can be notified via the Internet line connected to the image forming apparatus 1. It is also possible to take a method of directly informing (service zone).

Then, in the present embodiment, when the feed roller 53 and the separation roller 55 are replaced with new ones, the frequency (N value) at which the "empty drive mode" is executed is a preset initial value (default). It is controlled to be returned to (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 can be efficiently cleaned at the optimum frequency.

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

The "information related 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. It can be detected based on the 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, it is installed on the inlet guide plate in front of the nip portion). Since the amount of paper dust and calcium carbonate adhering to the roller surface of the feed roller 53 and the separation roller 55 varies depending on the paper type, brand, paper thickness, size, etc. of the sheet P, it is driven empty based on such information. By varying the mode execution frequency, the feed roller 53 and the separation roller 55 can be efficiently cleaned at an even more optimum frequency. Specifically, when the sheet P having a large amount of adhered paper dust, calcium carbonate, or the like is used, the N value is set to be small.

Further, the "information related to the cumulative number of sheets P fed" is the cumulative number of sheets P that have passed through the nip portion since the feed roller 53 and the separation roller 55 were in a new state, and image formation. It can be detected by a counter 82 built in the device 1.
Further, the "information related to the cumulative operating time of the feeding device 13" is the cumulative operating time of the DC motor 77 from the time when the feed roller 53 and the separation roller 55 are in a new state, and the image forming apparatus 1 has the information. It can be detected by the built-in timer 83.
When the cumulative number of sheets and the cumulative operating time increase, the unevenness of the roller surface of the feed roller 53 and the separation roller 55 is scraped off and becomes smooth, and foreign substances such as paper dust and calcium carbonate adhering to the roller surface cannot escape to the recesses. It becomes easy to be scattered on the roller surface, and the deterioration of the forward rotation of the separation roller 55 becomes easy to be promoted. Therefore, by changing the execution frequency of the empty drive mode based on the information, the feed roller 53 and the separation roller 55 can be efficiently cleaned at a more optimum frequency. Specifically, the N value is set to decrease as the cumulative number of sheets and the cumulative operating time increase.

Here, in the present embodiment, when the number of times that the seat P has not reached the predetermined time has been detected by the seat detection sensor 96 since the last time the "empty drive mode" was executed exceeds the predetermined number of times. , The "empty drive mode" is controlled to be executed more frequently (the N value becomes smaller). That is, if the number of times jam is detected by the seat detection sensor 96 since the previous execution of the empty drive mode is equal to or greater than the predetermined number of times, the N value is set to be small in the current empty drive mode. To do.
This is because when a lot of jam detections are detected by the sheet detection sensor 96, there is a high possibility that the feed roller 53 has a reduced transportability in addition to the poor rotation of the separation roller 55. In such a case, it is effective to set the N value small because such a problem can be easily solved by performing the "empty drive mode".

Hereinafter, as a summary, the control in the idle drive mode will be described with reference to the control flow of FIG.
As shown in FIG. 8, first, when the empty drive mode is executed in a state where the sheet P is not accommodated in the feeding device 13, the encoder 90 (or the detection unit 78) causes the encoder output value R (or DC). The motor applied current value) is acquired (step S1). That is, the encoder 90 (or the detection unit 78) detects the forward rotation of the separation roller 55.
Then, the output value R acquired in step S1 and the predetermined normal value R0 are compared, and it is determined whether or not the difference (R0-R) is equal to or greater than the threshold value A (step S2). As a result, when it is determined that the difference (R0-R) is not equal to or higher than the threshold value A, it is assumed that the forward rotation of the separation roller 55 hardly decreases, and the execution frequency (N value) of the idle drive mode is the default. The value (initial value) is maintained (step S3).
Then, it is determined whether or not the number of jam detections by the seat detection sensor 96 since the previous execution of the empty drive mode is equal to or less than a predetermined number of times (step S4). As a result, when it is determined that the number of jam detections is less than or equal to a predetermined value, it is assumed that the forward rotation of the separation roller 55 is lowered, and the execution frequency (N value) of the idle drive mode is set small (N value). Step S9), the next empty drive mode is executed immediately after the Nth seat 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 S4 that the number of jam detections is not less than or equal to the predetermined value, the information related to the next sheet P to be fed, the information related to the cumulative number of sheets P to be fed, and the feeding Based on the information related to the cumulative operating time of the apparatus 13, it is determined whether the condition is such that the forward rotation of the separation roller 55 is likely to decrease (step S5). As a result, when it is determined from the information that the condition is such that the forward rotation of the separation roller 55 is likely to decrease, the execution frequency (N value) of the idle drive mode is set small (step S9). Immediately after the Nth seat end is detected by the end detection sensor 95 based on the setting, the next empty drive mode is executed (step S7).
On the other hand, when it is determined in step S5 that the condition is not such that the forward rotation of the separation roller 55 is likely to decrease, the execution frequency (N value) of the idle drive mode is maintained at the default value. (Step S6), the next empty drive mode is executed immediately after the Nth seat 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 S2 that the difference (R0-R) is equal to or greater than the threshold value A, it is further determined whether the difference (R0-R) is equal to or greater than the threshold value 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 higher 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 of the separation roller 55. As a result, the empty drive mode is executed again within a predetermined number of times (steps S10 and S11). If it is determined that the difference (R0-R) is equal to or greater than the threshold value B even if the idle drive mode is performed a predetermined number of times in step S11, it is assumed that maintenance of the separation roller 55 and the feed roller 53 is required. , The idle drive mode is stopped (step S12) to notify that maintenance is required (step S13). After that, after it is confirmed that the separation roller 55 and the feed roller 53 have been maintained, the N value is returned to the default value (step S14).
Further, when it is determined in step S8 that the difference (R0-R) is not equal to or higher than the threshold value B, the separation roller 55 and the feed roller 53 have been cleaned to some extent, but the forwardness of the separation roller 55 is lowered. As an easy thing, the execution frequency (N value) of the empty drive mode is set small (step S9), and the next empty immediately after the end detection sensor 95 detects the Nth seat end 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 accompanies the rotation of the feed roller 53 in a state where the sheet P is not sandwiched between the nip portions of the feed roller 53 and the separation roller 55. An encoder 90 (or a detection unit 78) is provided as a detection means for detecting a rotating state. Then, when the encoder 90 (or the detection unit 78) detects that the separation roller 55 is in a bad state of being carried around, the sheet P is compared with the case where the separation roller 55 is detected in a good state of being carried around. It is controlled so that the execution frequency of the "empty drive mode", which is performed without feeding, increases.
As a result, the feed roller 53 and the separation roller 55 can be efficiently cleaned at an optimum frequency, and good feeding performance can be maintained even over time.

In the present embodiment, the present invention is applied to the feeding device 13 installed in the monochrome image forming apparatus 1, but naturally it is also applied to the feeding device installed in the color image forming apparatus 1. 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 are not limited to this. The present invention can also be applied to a feeding device installed in an image forming device (for example, an inkjet type image forming device, a stencil printing machine, etc.).
And even in such a case, the same effect as that 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 device 1, but the feeding device for manual feeding is installed so as to be exposed to the outside of the image forming device 1. The present invention can be applied to the feeding device 16, and the present invention can also be applied to the document transporting unit 10 (automatic document transporting device) as the feeding device.
Further, in the present embodiment, the present invention is applied to the FRR paper feeding type feeding device 13 in which the separation roller 55 is connected to the drive source (DC motor 77) via the torque limiter 56, but the drive source The present invention can also be applied to an RF paper feed type paper feed device (for example, the one disclosed in Patent Document 1) in which a separation roller having no separation roller is installed via a torque limiter. ..
And even in such a case, the same effect as that of the present embodiment can be obtained.

It is clear that the present invention is not limited to the present embodiment, and the present embodiment may be appropriately modified in addition to the suggestions in the present embodiment within the scope of the technical idea of the present invention. is there. Further, the number, position, shape, etc. of the constituent members are not limited to the present embodiment, and can be a suitable number, position, shape, etc. for carrying out the present invention.

In the specification of the present application and the like, the term "sheet" is defined to include all sheet-like members such as coated paper, label paper, transparencies, and films in addition to ordinary 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 Detection unit (detection means),
90 encoder (detection means),
91 photo sensor,
92 Detected plate,
95 end detection sensor,
96 Sheet detection sensor (sheet detection means),
P sheet.

JP-A-2007-119189 Japanese Unexamined Patent Publication No. 2002-255383 JP-A-2002-193466

Claims (10)

A feed roller that rotates along the feeding direction of the sheet to feed the sheet in the feeding direction, and
It is installed so as to form a nip portion between the feed roller and the feed roller, and when one sheet is sandwiched between the nip portions and when the sheet is not sandwiched between the nip portions, the feeding direction When a plurality of sheets are sandwiched between the nip portions, only the uppermost sheet among the plurality of sheets is fed in the feeding direction along the rotation of the feed roller. With a separation roller that separates the lower sheet from the uppermost sheet,
When the feed roller rotates along the feeding direction without the sheet being sandwiched between the nip portions, the separating roller rotates along the feeding direction with the rotation of the feed roller. Detection means to detect the state and
With
An air drive mode in which the feed roller is rotated along the feeding direction without feeding the seat is executed at a predetermined timing.
The value detected by the detection means exceeds a predetermined threshold value as compared with the normal value or the value detected by the detection means when the feed roller and the separation roller are new. A feeding device characterized in that when it becomes smaller, the air drive mode is controlled so as to be executed more frequently. Equipped with an end detection sensor that detects when all the seats housed in the feeder are gone.
When the number of times detected by the end detection sensor reaches N times, the empty drive mode is executed.
The value detected by the detection means exceeds a predetermined threshold value as compared with the normal value or the value detected by the detection means when the feed roller and the separation roller are new. The feeding device according to claim 1, wherein the N times are controlled to be a small value when the size is reduced. The feeding device according to claim 1 or 2, wherein the detection means is an encoder that detects the rotation speed of the separation roller. A DC motor that rotationally drives the feed roller and the separation roller,
When one sheet is sandwiched between the nip portions and when the sheet is not sandwiched between the nip portions, the drive transmission from the motor to the separation roller is cut off, and a plurality of sheets are sandwiched between the nip portions. When the seat is pinched, a torque limiter that transmits drive from the motor to the separation roller, and
With
The feeding device according to claim 1 or 2, wherein the detecting means is a means for detecting a current or a voltage applied to the DC motor. The feed according to any one of claims 1 to 4, wherein the timing at which the separation roller is detected by the detection means is the timing at which the idle drive mode is executed. apparatus. When the air drive mode is being executed and the value detected by the detection means becomes smaller than a predetermined value as compared with the normal value, the air drive mode is executed again. It is characterized in that even if the idle drive mode is executed a predetermined number of times, when the detection means detects that the state in which the separation roller is carried around is worse than the predetermined reference, it notifies that maintenance is required. The feeding device according to claim 5. The empty drive mode is executed based on at least one of information related to the sheets to be fed, information related to the cumulative number of sheets fed, and information related to the cumulative operating time of the feeding device. The feeding device according to any one of claims 1 to 6, wherein the frequency of the feeding device is variable. A sheet detection sensor for detecting 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 position within a predetermined time is provided.
When the number of times that the sheet detection sensor has detected a state in which the state has not been reached within the predetermined time exceeds the predetermined number of times since the last time the empty drive mode was executed, the empty drive mode is frequently executed. The feeding device according to any one of claims 1 to 7, wherein the feeding device is controlled so as to be. Claims 1 to 8 are characterized in that when the feed roller and the separation roller are replaced with new ones, the frequency with which the air drive mode is executed is returned to a preset initial value. The feeding device according to any one of. An image forming apparatus comprising the feeding apparatus according to any one of claims 1 to 9.

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