Sheet conveyance apparatus, document feeding apparatus, document reading apparatus, and image forming apparatus

Patent metadata

Field	Value
Publication number	US-10723574-B2
Application number	US-201816218871-A
Country	US
Kind code	B2
Filing date	Dec 13, 2018
Priority date	Jan 16, 2018
Publication date	Jul 28, 2020
Grant date	Jul 28, 2020

Abstract

A sheet conveyance apparatus includes a stacking unit having a sheet, a feeding unit, a conveyance roller to convey a sheet fed by the feeding unit, a motor to drive the conveyance roller, a phase determiner, first and second controllers, and a discriminator. The feeding unit feeds the sheet. The phase determiner determines a motor rotor rotational phase. The first controller controls a drive current flowing in a motor winding to reduce a deviation between an instructed phase of the motor rotor and the determined rotational phase. The second controller controls to perform a first drive for driving the conveyance roller for a predetermined time before a feeding unit feed operation is started. The discriminator discriminates presence or absence of the sheet at a nip portion of the conveyance roller based on a value of a parameter corresponding to load torque applied to the rotor during the first drive.

First claim

What is claimed is:

1. A sheet conveyance apparatus comprising:
a stacking unit on which a sheet is to be stacked;
a feeding unit configured to feed the sheet stacked on the stacking unit;
a first conveyance roller configured to convey the sheet fed by the feeding unit;
a motor configured to drive the first conveyance roller;
a phase determiner configured to determine a rotational phase of a rotor of the motor;
a first controller configured to control a drive current flowing in a winding of the motor to reduce a deviation between an instructed phase representing a target phase of the rotor of the motor and the rotational phase determined by the phase determiner;
a second controller configured to control the first controller to perform a first drive for driving the first conveyance roller before a feed operation by the feeding unit is started; and
a discriminator configured to discriminate presence or absence of the sheet at a nip portion of the first conveyance roller based on a value of a parameter corresponding to load torque applied, during the first drive, to the rotor.

2. The sheet conveyance apparatus according to claim 1 , further comprising a second conveyance roller adjacent to the first conveyance roller,
wherein the second controller drives the first and second conveyance rollers during the first drive, and
wherein, based on the parameter value, the discriminator discriminates presence or absence of the sheet at the nip portion of the first conveyance roller.

3. The sheet conveyance apparatus according to claim 2 , wherein an upstream conveyance roller is disposed on an upstream side in a sheet conveyance direction, the sheet conveyance apparatus further comprising a third conveyance roller adjacent to the upstream conveyance roller,
wherin the upstream conveyance roller is one of the first and second conveyance rollers,
wherein the third conveyance roller is disposed on an upstream side of the upstream conveyance roller in the sheet conveyance direction,
wherein, after the discrimination by the discriminator during the first drive is completed and before the feed operation is started, the second controller performs a second drive for driving the third conveyance roller, from a stop state, and driving the upstream conveyance roller,
wherein, the parameter is a first parameter, the rotor is a first rotor, and the motor is a first motor,
wherein a value of a second parameter corresponds to load torque applied, during the second drive, to a second rotor of a second motor for driving, as a driven conveyance roller, one of the upstream conveyance roller or the third conveyance roller, and
wherein, based on the second parameter value, the discriminator discriminates presence or absence of the sheet at a nip portion of the driven conveyance roller driven by the second motor.

4. The sheet conveyance apparatus according to claim 3 , wherein a circumferential speed of the third conveyance roller is lower than a circumferential speed of the upstream conveyance roller.

5. The sheet conveyance apparatus according to claim 2 , wherein a circumferential speed of an upstream conveyance roller disposed on an upstream side in a sheet conveyance direction out of the first and the second conveyance rollers is lower than a circumferential speed of a downstream conveyance roller on a downstream side in the sheet conveyance direction out of the first and second conveyance rollers.

6. The sheet conveyance apparatus according to claim 2 , further comprising:
a third conveyance roller disposed on an upstream side of the first and second conveyance rollers in a sheet conveyance direction; and
a fourth conveyance roller adjacent to the third conveyance roller,
wherein, after the discrimination by the discriminator during the first drive is completed and before the feed operation is started, the second controller starts a second drive for driving the third and fourth conveyance rollers for a predetermined time period,
wherein, the parameter is a first parameter, the rotor is a first rotor, and the motor is a first motor,
wherein a value of a second parameter corresponds to load torque applied, during the second drive, to a second rotor of a second motor for driving, as a driven conveyance roller, one of the third and fourth conveyance rollers, and
wherein, based on the second parameter value, the discriminator discriminates presence or absence of the sheet at a nip portion of the driven conveyance roller driven by the second motor.

7. The sheet conveyance apparatus according to claim 6 , wherein a circumferential speed of an upstream conveyance roller disposed on the upstream side in the sheet conveyance direction out of the third and fourth conveyance rollers is lower than a circumferential speed of a downstream conveyance roller on a downstream side in the sheet conveyance direction out of the third and fourth conveyance rollers.

8. The sheet conveyance apparatus according to claim 6 , wherein a downstream conveyance roller on a downstream side in the sheet conveyance direction out of the third and fourth conveyance rollers is adjacent to an upstream conveyance roller disposed on the upstream side in the sheet conveyance direction out of the first and second conveyance rollers.

9. The sheet conveyance apparatus according to claim 8 , wherein a circumferential speed of the downstream conveyance roller is lower than a circumferential speed of the upstream conveyance roller.

10. The sheet conveyance apparatus according to claim 2 ,
wherein the second conveyance roller is disposed adjacent to the first conveyance roller on an upstream side of the first conveyance roller in a sheet conveyance direction,
wherein, after the discrimination by the discriminator during the first drive is completed and before the feed operation is started, the second controller performs a second drive for driving the second conveyance roller for a predetermined time period,
wherein, the parameter is a first parameter, the rotor is a first rotor, and the motor is a first motor,
wherein a value of a second parameter corresponds to load torque applied, during the second drive, to a second rotor of a second motor for driving the second conveyance roller, and
wherein, based on the second parameter value, the discriminator discriminates presence or absence of the sheet at a nip portion of the second conveyance roller driven by the second motor.

11. The sheet conveyance apparatus according to claim 1 , further comprising:
a second conveyance roller adjacent to the first conveyance roller, and disposed on an upstream side of the first conveyance roller in a sheet conveyance direction;
a second motor configured to drive the second conveyance roller; and
a third controller configured to control the second motor,
wherein, during the first drive, the third controller controls the second motor to prevent rotation of the second conveyance roller by the conveyance of the sheet by the first conveyance roller, even in a state of the sheet being nipped by the second conveyance roller, and
wherein, during the first drive, the discriminator discriminates presence or absence of the sheet at the nip portion of the first conveyance roller based on the parameter value.

12. The sheet conveyance apparatus according to claim 1 ,
wherein the parameter corresponding to the load torque is the deviation between the instructed phase and the rotational phase, and
wherein, in a case where an absolute value of the deviation is larger than a predetermined value, the discriminator discriminates that the sheet is present at the nip portion of the first conveyance roller.

13. The sheet conveyance

Assignees

• Canon Kk

Inventors

• Miyazawa Toru
• Kumagai Shigemi

Classifications

• G03G15/602 Primary

  for transporting · CPC title

• H02P6/085

  in a bridge configuration · CPC title

• B65H2511/528

  Jam · CPC title

• H02P21/22

  Current control, e.g. using a current control loop · CPC title

• H04N1/00689

  Presence · CPC title