Sheet conveying apparatus and image forming apparatus

A sheet conveying apparatus for conveying a sheet, the sheet conveying apparatus comprising:

• a first conveying roller configured to convey the sheet;
• a second conveying roller adjoining the first conveying roller;
• a motor configured to drive the first conveying roller;
• a phase determiner configured to determine a rotational phase of a rotor of the motor;
• a controller configured to control a drive current flowing through a winding of the motor such that a deviation between an instruction phase indicating a target phase of the rotor and the rotational phase determined by the phase determiner is reduced;
• and
• a discriminator configured to execute discrimination with respect to at least one of whether a front end of the sheet has reached a nip portion of a downstream conveying roller which is on a downstream side of the first and second conveying rollers in a conveying direction in which the sheet is conveyed, or whether a rear end of the sheet has passed through a nip portion of an upstream conveying roller which is on an upstream side of the first and second conveying rollers in the conveying direction,
• wherein the controller controls the drive current flowing through the winding of the motor such that the first conveying roller rotates at a first peripheral velocity which is different from a second peripheral velocity of the second conveying roller, and
• wherein the discriminator executes the discrimination based on a value of a parameter corresponding to a load torque applied to the rotor in a state where the first conveying roller rotates at the first peripheral velocity which is different from the second peripheral velocity of the second conveying roller.

A sheet conveying apparatus apparatus, for conveying a sheet, the sheet conveying apparatus comprising:

• a first conveying roller configured to convey the sheet;
• a second conveying roller adjoining the first conveying roller;
• a motor configured to drive the first conveying roller;
• a phase determiner configured to determine a rotational phase of a rotor of the motor;
• a controller configured to control a drive current flowing through a winding of the motor such that a deviation between an instruction phase indicating a target phase of the rotor and the rotational phase determined by the phase determiner is reduced;
• and
• a discriminator configured to output, in a case where an absolute value of a parameter corresponding to a load torque applied to the rotor is greater than a predetermined value, a signal indicating that a front end of the sheet has reached a nip portion of a downstream conveying roller which is on a downstream side of the first and second conveying rollers in a conveying direction in which the sheet is conveyed,
• wherein, in a period from when the front end of the sheet has reached a predetermined position upstream of the nip portion of the downstream conveying roller in the conveying direction until when the signal indicating that the front end of the sheet has reached the nip portion of the downstream conveying roller is output from the discriminator, the controller controls the motor such that the first conveying roller rotates at a peripheral velocity which is different from a peripheral velocity of the second conveying roller, and
• wherein the controller controls the motor such that a difference between the first and second peripheral velocities after the signal indicating that the front end of the sheet has reached the nip portion of the downstream conveying roller is output from the discriminator, is smaller than the difference between the first and second peripheral velocities in the period.

A sheet conveying apparatus, for conveying a sheet, the sheet conveying apparatus comprising:

• a first conveying roller configured to convey the sheet;
• a second conveying roller adjoining the first conveying roller;
• a motor configured to drive the first conveying roller;
• a velocity determiner configured to determine a rotational velocity of a rotor of the motor;
• a controller configured to control a drive current flowing through a winding of the motor such that a deviation between an instruction velocity indicating a target velocity of the rotor and the rotational velocity determined by the velocity determiner is reduced;
• and
• a discriminator configured to output, in a case where an absolute value of a parameter corresponding to a load torque applied to the rotor is greater than a predetermined value, a signal indicating that a front end of the sheet has reached a nip portion of a downstream conveying roller which is on a downstream side of the first and second conveying rollers in a conveying direction in which the sheet is conveyed,
• wherein, in a period from when the front end of the sheet has reached a predetermined position upstream of the nip portion of the downstream conveying roller in the conveying direction until when the signal indicating that the front end of the sheet has reached the nip portion of the downstream conveying roller is output from the discriminator, the controller controls the motor such that the first conveying roller rotates at a first peripheral velocity which is different from a second peripheral velocity of the second conveying roller, and
• wherein the controller controls the motor such that a difference between the first and second peripheral velocities after the signal indicating that the front end of the sheet has reached the nip portion of the downstream conveying roller is output from the discriminator, is smaller than the difference between the first and second peripheral velocities in the period.

An image forming apparatus for forming an image on a sheet, the image forming apparatus comprising:

• an image forming unit configured to form the image on the sheet;
• a fixing roller configured to fix, to the sheet, the image formed on the sheet by the image forming unit;
• a conveying roller provided downstream of the fixing roller in a conveying direction in which the sheet is conveyed;
• a motor configured to drive the conveying roller;
• a phase determiner configured to determine a rotational phase of a rotor of the motor;
• a controller configured to control a drive current flowing through a winding of the motor such that a deviation between an instruction phase indicating a target phase of the rotor and the rotational phase determined by the phase determiner is reduced;
• and
• a discriminator configured to output, in a case where an absolute value of a parameter corresponding to a load torque applied to the rotor is greater than a predetermined value, a signal indicating that a rear end of the sheet has passed through a nip portion of the fixing roller,
• wherein, in a period from when the driving of the conveying roller is started until when the signal indicating that the rear end of the sheet has passed through the nip portion of the fixing roller is output from the discriminator, the controller controls the drive current such that a peripheral velocity of the conveying roller becomes a first velocity which is greater than a peripheral velocity of the fixing roller, and
• wherein, in a case where the signal indicating that the rear end of the sheet has passed through the nip portion of the fixing roller is output from the discriminator, the controller controls the drive current such that the peripheral velocity of the conveying roller becomes a second velocity which is greater than the first velocity.

An image forming apparatus for forming an image on a sheet, the image forming apparatus comprising:

• an image forming unit configured to form the image on the sheet;
• a fixing roller configured to fix, to the sheet, the image formed on the sheet by the image forming unit;
• a conveying roller provided downstream of the fixing roller in a conveying direction in which the sheet is conveyed;
• a motor configured to drive the conveying roller;
• a velocity determiner configured to determine a rotational velocity of a rotor of the motor;
• a controller configured to control a drive current flowing through a winding of the motor such that a deviation between an instruction velocity indicating a target velocity of the rotor and the rotational velocity determined by the velocity determiner is reduced;
• and
• a discriminator configured to output, in a case where an absolute value of a parameter corresponding to a load torque applied to the rotor is greater than a predetermined value, a signal indicating that a rear end of the sheet has passed through a nip portion of the fixing roller,
• wherein, in a period from when the driving of the conveying roller is started until when the signal indicating that the rear end of the sheet has passed through the nip portion of the fixing roller is output from the discriminator, the controller controls the drive current such that a peripheral velocity of the conveying roller becomes a first velocity which is greater than a peripheral velocity of the fixing roller, and
• wherein, in a case where the signal indicating that the rear end of the sheet has passed through the nip portion of the fixing roller is output from the discriminator, the controller controls the drive current such that the peripheral velocity of the conveying roller becomes a second velocity which is greater than the first velocity.

A sheet conveying apparatus, comprising:

• a storing tray configured to store the sheet;
• a pickup roller configured to feed the sheet stored in the storing tray;
• a feed roller adjoining the pickup roller and configured to convey the sheet fed by the pickup roller to a downstream side of the feed roller;
• a conveying roller adjoining the feed roller and configured to convey the sheet conveyed by the feed roller further to the downstream side;
• a motor configured to drive the conveying roller;
• a phase determiner configured to determine a rotational phase of a rotor of the motor;
• a controller configured to control a drive current flowing through a winding of the motor such that a deviation between an instruction phase indicating a target phase of the rotor and the rotational phase determined by the phase determiner is reduced;
• and
• a discriminator configured to execute discrimination with respect to at least one of whether a front end of the sheet has reached a nip portion of the conveying roller, or whether a rear end of the sheet has passed through a nip portion of the feed roller,
• wherein the controller controls the drive current flowing through the winding of the motor such that the conveying roller rotates at a first peripheral velocity which is greater than a peripheral velocity of the feed roller, and
• wherein the discriminator executes the discrimination based on a value of a parameter corresponding to a load torque applied to the rotor in a state where the conveying roller rotates at the peripheral velocity which is greater than a peripheral velocity of the feed roller.

A sheet conveying apparatus, comprising:

• a storing tray configured to store the sheet;
• a pickup roller configured to feed the sheet stored in the storing tray;
• a feed roller adjoining the pickup roller and configured to convey the sheet fed by the pickup roller to a downstream side of the feed roller;
• a conveying roller adjoining the feed roller and configured to convey the sheet conveyed by the feed roller further to the downstream side;
• a motor configured to drive the conveying roller;
• a velocity determiner configured to determine a rotational velocity of a rotor of the motor;
• a controller configured to control a drive current flowing through a winding of the motor such that a deviation between an instruction velocity indicating a target velocity of the rotor and the rotational velocity determined by the velocity determiner is reduced;
• and
• a discriminator configured to execute discrimination with respect to at least one of whether a front end of the sheet has reached a nip portion of the conveying roller, or whether a rear end of the sheet has passed through a nip portion of the feed roller,
• wherein the controller controls the drive current flowing through the winding of the motor such that the conveying roller rotates at a peripheral velocity which is greater than a peripheral velocity of the feed roller, and
• wherein the discriminator executes the discrimination based on a value of a parameter corresponding to a load torque applied to the rotor in a state where the conveying roller rotates at the peripheral velocity which is greater than a peripheral velocity of the feed roller.