JP5451278B2 - Paper feeder - Google Patents

Description

  The present invention relates to a paper feeding device for an image forming apparatus such as a copying machine, a printer, a facsimile machine or the like.

  In a conventional image forming apparatus, as a configuration for feeding recording sheets, a plurality of recording sheets stacked on a stacking plate of a sheet feeding cassette are lifted up, and then the uppermost recording sheet in the recording sheet bundle is picked up. The paper is taken out and fed by a roller. The lift of the recording sheet bundle and the pickup of the recording sheets were driven by separate motors. On the other hand, for example, Patent Document 1 discloses a sheet feeding device that uses both a forward and reverse rotation of a single stepping motor and a one-way clutch for both cost reduction and a lift-up motor.

JP 2002-321837 A

  However, in the configuration in which a single motor is used and lift-up and pickup are performed by forward / reverse rotation of the motor, as in the sheet supply device of Patent Document 1, the motor vibration is generated when the motor is stopped and immediately reversely rotated. It will occur. If the lift-up and pick-up are continuously switched while the motor is still vibrating, there has been a problem that the operation of the motor becomes unstable, for example, the motor vibration increases and the motor steps out.

  The present invention has been made paying attention to the above points, and an object of the present invention is to provide a paper feeding device that can prevent motor step-out due to motor vibration and can stabilize lift-up and pickup operations. .

  In order to achieve the above object, the present invention comprises the following arrangement.

(1) A stacking table on which a plurality of sheets are stacked, a pickup roller that feeds the uppermost sheet of the plurality of sheets stacked on the stacking table, and the uppermost sheet for contacting the pickup roller A lift-up means for raising the loading platform; a motor for operating the pickup roller by rotation in a first direction; and operating the lift-up means by rotation in a second direction; Control means for controlling the operation of the lift-up means, and the control means operates the pickup roller by rotating the motor in the first direction, and operates the pickup roller by stopping the motor. After the end of, the start of the operation of the lift-up means is prohibited for a first predetermined time, and further, the first predetermined time When the lift-up unit is operated by rotating the motor in the second direction after the elapse of time, the operation of the pickup roller is started after the end of the operation of the lift-up unit by stopping the motor. The pickup determined by the feeding interval when it is impossible to maintain a predetermined sheet feeding interval by the pickup roller by prohibiting the pickup roller for a predetermined time and prohibiting the start of the operation of the pickup roller for the second predetermined time. The sheet feeding device , wherein the operation of the lift-up unit is interrupted at a timing going back from the operation start timing to the first predetermined time .
(2) A stacking table on which a plurality of sheets are stacked, a pickup roller that feeds the uppermost sheet of the plurality of sheets stacked on the stacking table, and the uppermost sheet for contacting the pickup roller A lift-up means for raising the loading platform; a motor for operating the pickup roller by rotation in a first direction; and operating the lift-up means by rotation in a second direction; Control means for controlling the operation of the lift-up means, and the control means operates the pickup roller by rotating the motor in the first direction, and operates the pickup roller by stopping the motor. After the end of, the start of the operation of the lift-up means is prohibited for a first predetermined time, and further, the first predetermined time When the lift-up unit is operated by rotating the motor in the second direction after the elapse of time, the operation of the pickup roller is started after the end of the operation of the lift-up unit by stopping the motor. When a plurality of sheets are fed by providing a constant speed section for a certain period before accelerating the motor when starting the operation of the pickup roller, which is prohibited for a predetermined time, the first constant speed section Is made longer than the constant speed section of the second and subsequent sheets.

  By having the above-described configuration, the present invention reliably lifts up in a time region where the motor vibration after the pickup has been stabilized, and further reliably picks up in the time region where the motor vibration is stable after the lift-up is completed. Can be done. Therefore, it is possible to provide a paper feeding device that can prevent motor step-out due to motor vibration and stabilize lift-up and pickup operations.

1 is an overall configuration diagram of an image forming apparatus according to an embodiment. Sectional view of the paper feed configuration of the embodiment 1 is a block diagram showing the configuration of an image forming apparatus according to an embodiment 6 is a flowchart illustrating a sequence of the sheet feeding device according to the embodiment. The figure which shows the timing of the motor drive of embodiment

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, the best mode for carrying out the invention will be described with reference to the drawings.

[Embodiment]
FIG. 1 shows the overall configuration of the image forming apparatus.

  The image forming apparatus includes a reader unit 1R and a printer unit 1P. In the printer unit 1P, yellow, magenta, cyan, and black toner images are formed on the photosensitive drums 11a to 11d in the image forming unit 10 and transferred onto the intermediate transfer belt 31 in an overlapping manner.

  The paper feeding unit 20 includes paper feeding cassettes 21a and 21b and a manual feed tray 27 for storing the recording sheets P, and a pickup roller 22a for feeding the recording sheets P one by one from the paper feeding cassettes 21a, 21b or the manual feeding tray 27. , 22b, 26. Further, the recording sheet P fed from each pickup roller is further transferred to the sheet feeding roller 23, the sheet feeding guide 24, and the recording sheet P in accordance with the image forming timing of each image forming unit. And a registration roller 25 for feeding to the area.

  Next, a sheet feeding operation of the image forming apparatus having the above configuration will be described.

  When a recording sheet is fed from the sheet feeding cassette 21a, when a start signal for an image forming operation is issued, the stepping motor 205a is first driven, and the driving force is transmitted to the pickup roller 22a. As a result, the pickup roller 22a rotates and the recording sheets P are sent out one by one from the paper feed cassette 21a. The recording sheet P is guided between the sheet feeding guides 24 by the sheet feeding roller 23 and conveyed to the registration rollers 25. At that time, the registration roller 25 is stopped, and the leading edge of the recording sheet P hits the nip portion. Thereafter, the registration roller starts rotating in accordance with the timing at which the image forming unit 10 starts image formation. The toner image transferred to the intermediate transfer belt 31 is transferred to the recording sheet P conveyed by driving the registration roller. The toner image transferred to the recording sheet P is fixed by the fixing device 40 and discharged outside the apparatus.

  FIG. 2 is a cross-sectional view showing details of the paper feed mechanism in the paper feed cassette 21a. Since the paper feed mechanism of the paper feed cassette 21b has the same configuration, only the paper feed mechanism of the paper feed cassette 21a will be described.

  When the stepping motor 205a and the motor output shaft 205b are rotated in the counterclockwise direction (first direction), the recording sheet is lifted up. When the stepping motor 205a and the motor output shaft 205b are rotated in the clockwise direction (second direction), the recording sheet is Perform pickup operation.

  A recording sheet bundle (a plurality of sheets) is stacked by the user on the bottom plate 201 which is a stacking table. The bottom plate 201 and the roller 202 are connected by a wire 203. As the motor output shaft 205b rotates, the one-way clutch-equipped gear 204 rotates, so that the roller 202 rotates in the direction of winding the wire 203 and the bottom plate 201 rises. As a result, the recording sheet is lifted up. The gear 206 with the one-way clutch does not rotate clockwise, so that the driving force of the stepping motor 205a is not transmitted to the pickup roller 22. When the uppermost recording sheet comes into contact with the pickup roller 22, the roller 22 rises, and a flag on the opposite side of the pickup roller 22 around the shaft 209 is detected by the paper surface height sensor 210. The drive of the stepping motor 205a is stopped by the detection signal.

  On the other hand, during the pickup operation, the rotation of the motor output shaft 205 b is transmitted to the pickup roller 22 through the gear 206 with a one-way clutch and further through the reduction gear 207. Since the one-way clutch gear 204 does not rotate counterclockwise, the driving force of the stepping motor 205 a is not transmitted to the roller 202. As the pickup roller 22 rotates, the uppermost recording sheet in contact with the pickup roller 22 is sent out.

  FIG. 3 is a block diagram illustrating a configuration of the image forming apparatus, and more particularly, a block diagram illustrating a configuration related to a paper feeding mechanism of the paper feeding device.

  When an image formation start instruction is input from the user interface unit 306 to the controller unit 307, the controller unit 307 instructs the printer control unit 302 to start an image forming job. The printer control unit 302 outputs drive instruction information for the stepping motor 205 a to the motor control unit 303 based on input information from the paper surface height sensor 210. The motor control unit 303 drives the stepping motor 205 a based on the drive information from the printer control unit 302. When the stepping motor 205a is driven, the one-way clutch gears 206 and 204 are rotated. When the rotation direction of the stepping motor 205a is reversed in the normal direction, the pickup roller 22 or the gear 204 with the one-way clutch rotates. And the bottom plate 201 raises by the gear 204 with a one-way clutch rotating.

  FIG. 4 is a flowchart showing a lift-up and pickup sequence of the paper feeding apparatus according to the present invention.

  After the copy start instruction, the printer control unit 302 instructs the motor control unit 303 to rotate the stepping motor in the second direction, and starts a pickup operation (S402). Then, the printer control unit 203 instructs the motor control unit 303 to stop driving the stepping motor 205a after driving the stepping motor 205a for a time during which the recording sheet can be sent out. Thereby, the pickup of one recording sheet is completed (S403). Then, the printer control unit 302 waits for the lift-up prohibition time (predetermined time prohibition) to elapse (S404), and the uppermost recording sheet loaded on the paper feed unit comes into contact with the pickup roller 22 to increase the paper surface height. It is determined whether the sensor is on (S405). If the paper surface height sensor is on, the printer control unit 302 determines whether or not there is a next image formation (S406). When there is the next image formation, the printer control unit 302 instructs the motor control unit 303 to rotate the stepping motor 205a in the second direction, and performs the next pickup (S402).

  On the other hand, if the paper surface height sensor 210 is not turned on in step S405, the printer control unit 302 starts the lift-up by driving the stepping motor to rotate in the first direction (S407). When the lift-up is started, the printer control unit 302 determines whether or not the paper height sensor 210 is turned on (S408). When the paper surface height sensor 210 is turned on, the printer control unit 302 continues to lift up for 10 ms after the paper surface height sensor is turned on in order to remove chattering of the paper surface height sensor 210 (S409). Then, the printer control unit 302 gives a control instruction to stop the motor to the motor control unit (S410), the stepping motor stops, and the lift-up ends.

  Thereafter, the printer control unit 302 waits for a certain period of time as the pickup prohibition time (S411), and determines whether there is a next image formation after the certain period of time (S406). If there is a next image formation, the process returns to step S402 to start picking up again. In step S406, if there is no next image formation, the printer control unit 302 ends the copying.

  In the flowchart of FIG. 4, the process starts from the pickup. This is because the lift-up operation is executed at the initialization after the power of the image forming apparatus is turned on, and the paper height detection sensor 210 is turned on at the time of the copy start. It is because it is in the state which is doing.

  FIG. 5 shows the drive timing and rotation speed of the stepping motor. As an example, driving at the time of copying 11 sheets is shown.

  After the start of copying, at the pickup time t1, the stepping motor rotates in the normal direction (second direction) and performs driving having an acceleration period and a deceleration period. A constant speed section of a fixed period is provided at the beginning of the pickup time t1, and acceleration is performed after the vibration at the start of rotation of the stepping motor is stabilized.

  After the pickup time t1, the lift-up prohibition time t2 is reached. Even when the first pick-up operation is performed, the paper surface height sensor 210 is not turned off, so that the lift-up operation is not performed. Thereafter, the second sheet is picked up. Also in the pickup time t3 for the second and subsequent sheets, the stepping motor 205a rotates in the forward direction and is driven to accelerate, constant speed, and decelerate. Similarly to the first sheet, the second and subsequent sheets are first provided with a constant speed section for a certain period, and acceleration is performed after the vibration at the start of rotation of the stepping motor is stabilized. Note that the first constant speed period at the first sheet pickup time t1 is longer than the first constant speed period at the second and subsequent pickup times t3. The reason for this is that the stepping motor 205a is excited from the non-excited state, while the second and subsequent sheets are driven from the excited state. The first sheet is longer than the second sheet.

  When the sheet height sensor 210 is turned off when the 10th sheet is fed, the lift-up time t4 is reached after the lift-up prohibition time t2, and the lift-up is performed. At the time of lift-up, the rotation direction of the stepping motor is reverse (first direction) and is driven at a constant speed. Then, after the paper surface height sensor 210 is turned on and 10 ms elapses, the lift-up is completed. After the lift-up is completed, a pickup prohibition time t5 is provided. After the pickup prohibition time t5 elapses, the eleventh pickup is performed. Then, since there is no next image formation, the copying is completed, and the image forming apparatus is in a standby state waiting for image formation.

  As described above, the paper feeding device according to the present embodiment reliably lifts up after the motor vibration after the pickup is stabilized, and even after the lift-up is completed, the pickup is reliably performed after the motor vibration is stabilized. Can be done.

  In FIG. 5, there is a blank time between the lift-up prohibition time t2 after the first pick-up time t1 and the second pick-up period t3. This time is determined by the required paper feed interval, and the pick-up operation may be started immediately after the lift-up prohibition time t2.

In addition, because there is a pick-up prohibition time t5 after the Rifutoa-up time t4, it is as it is, sometimes feeding interval of 10 sheet and 11 sheet is longer than the earlier of the paper feed interval. In such a situation, in order to maintain the predetermined sheet feeding interval, the printer control unit 302 interrupts the lift-up operation even during the lift-up period t5, and the predetermined pickup is performed. The prohibited time (t5) is secured. That is, the printer control unit 302 interrupts the lift-up operation at a timing that is earlier than the timing at which the pickup operation is started at a predetermined paper feed interval by the pickup prohibition time. In other words, the printer control unit 302 makes the lift-up operation time shorter than the specified time. Even when the lift-up is interrupted, the lift-up is performed by adding 10 ms for removing chattering, so that the pickup roller 22 can send out the uppermost sheet.

  As described above, according to the present embodiment, lift-up and pickup can be performed with a small number of motors, and stable pickup and lift-up can be performed.

22a, 22b Pickup roller 201 Bottom plate 204, 206 Gear 205a with one-way clutch Stepping motor 302 Printer control unit 303 Motor control unit

Claims (6)

A loading table on which a plurality of sheets are loaded;
A pick-up roller for sending out the uppermost sheet of the plurality of sheets stacked on the stacking table;
Lift-up means for raising the stack to bring the uppermost sheet into contact with the pickup roller;
A motor that operates the pickup roller by rotation in a first direction and operates the lift-up means by rotation in a second direction;
Control means for controlling the operation of the pickup roller and the operation of the lift-up means;
Have
The control means rotates the motor in the first direction to operate the pickup roller, and after the operation of the pickup roller due to the stop of the motor is finished, starts the operation of the lift-up means for the first time. When the lift-up means is operated by prohibiting the predetermined time and further operating the lift-up means by rotating the motor in the second direction after elapse of the first predetermined time, the operation of the lift-up means is terminated by stopping the motor. Thereafter, the start of the operation of the pickup roller is prohibited for a second predetermined time ,
In the case where it becomes impossible to maintain the predetermined sheet feeding interval by the pickup roller by prohibiting the start of the operation of the pickup roller for the second predetermined time, from the start timing of the pickup operation determined by the feeding interval The sheet feeding device , wherein the operation of the lift-up unit is interrupted at a timing going back the first predetermined time . 2. The sheet feeding device according to claim 1 , wherein the control unit starts the operation of the pickup roller after the first predetermined time has elapsed since the operation of the lift-up unit is interrupted. A loading table on which a plurality of sheets are loaded;
A pick-up roller for sending out the uppermost sheet of the plurality of sheets stacked on the stacking table;
Lift-up means for raising the stack to bring the uppermost sheet into contact with the pickup roller;
A motor that operates the pickup roller by rotation in a first direction and operates the lift-up means by rotation in a second direction;
Control means for controlling the operation of the pickup roller and the operation of the lift-up means;
Have
The control means rotates the motor in the first direction to operate the pickup roller, and after the operation of the pickup roller due to the stop of the motor is finished, starts the operation of the lift-up means for the first time. When the lift-up means is operated by prohibiting the predetermined time and further operating the lift-up means by rotating the motor in the second direction after elapse of the first predetermined time, the operation of the lift-up means is terminated by stopping the motor. Thereafter, the start of the operation of the pickup roller is prohibited for a second predetermined time,
When the operation of the pickup roller is started, a constant speed section of a certain period is provided before the motor is accelerated, and when a plurality of sheets are fed, the first constant speed section is set to the second and subsequent sheets. A sheet feeding device characterized in that it is longer than the constant speed section . When the control means starts the operation of the pickup roller and provides a constant speed section for a certain period before accelerating the motor, and feeding a plurality of sheets, the first constant speed section sheet feeding apparatus according to claim 1 or 2, characterized in that the longer than second and subsequent constant speed. Detecting means for detecting the uppermost surfaces of the plurality of sheets stacked on the stacking table;
The control means determines whether or not the detection means has detected the uppermost surface after the first predetermined time has elapsed after completion of the pickup operation, and the detection means has not detected the uppermost surface. The sheet feeding device according to any one of claims 1 to 4, wherein the lift-up unit is operated.   The sheet feeding device according to claim 1, wherein the motor is a stepping motor.

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