US 7,971,868 B2Granted

Sheet feeding apparatus and image forming apparatus with lifter mechanism

AssigneeCanon Kabushiki Kaisha

InventorsAkira Matsushima, Minoru Kawanishi, Yasuhiro Uchida, Eiji Wakiyama

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Abstract

A sheet feeding apparatus includes a middle plate, a lifter mechanism, and a sheet-feed roller. The sheet-feed roller can move to a first position retracted from the sheet, a second position lower than the first position for feeding the sheet, and a third position lower than the second position. The sheet feeding apparatus has a position control mode in which when a sheet is fed, the sheet-feed roller is moved from the first position to the third position and stopped there, the middle plate is moved toward the sheet-feed roller by the lifter mechanism, the sheet stacked on the middle plate is brought into abutment against the sheet-feed roller, the middle plate is moved until a position detection sensor outputs the detection signal that the sheet-feed roller is in the second position, and a height of the sheet is controlled.

Claims16

Dependent claims

A sheet feeding apparatus comprising

a sheet stacking member configured to stack sheets,
a sheet feeding member which is moveable between a standby position in a sheet feeding standby state and a sheet feeding position below the standby position, and which is configured to engage with an upper surface of a topmost sheet of the sheets stacked on the sheet stacking member to feed the sheet at the sheet feeding position, and in a middle of a sheet feeding operation of the sheet feeding member, the sheet feeding member is returned to the standby position,
a sheet feed motor configured to drive the sheet feed member to feed the sheet,
a moving mechanism configured to move the sheet feeding member between the standby position and the sheet feeding position by a drive of the sheet feed motor,
a position detector, operable to output a detection signal based on a position of the sheet feeding member, and
a lifter mechanism which is configured to lift the sheet stacking member towards the sheet feeding member, the lifter mechanism lifts,
the sheet stacking member based on detection of the position detector, such that the upper surface of the topmost sheet is moved to the sheet-feeding position,
wherein when a first sheet feeding operation of the sheet feeding member starts after sheets are set on the sheet stacking member in a lower position, the sheet feed motor rotates by a predetermined amount and stops so that the sheet feeding member is lowered from the standby position towards the sheet feeding position by the moving mechanism in a state that the sheet stacking member is in the lower position, and
wherein when the sheet feeding member is lowered from the standby position towards the sheet feeding position in the first sheet feeding operation, the sheet stacking member is lifted by the lifter mechanism based on detection of the position detector so that the upper surface of the sheet stacked on the sheet stacking member is moved to the sheet-feeding position.

6 more elements

An image forming apparatus which feeds a sheet and forms an image, comprising

a sheet feeding apparatus comprising
a sheet stacking member configured to stack sheets,
a sheet feeding member which is moveable between a standby position in a sheet feeding standby state and a sheet feeding position below the standby position, and which is configured to engage with an upper surface of a topmost sheet of the sheets stacked on the sheet stacking member to feed the sheet at the feeding position, and in a middle of a sheet feeding operation of the sheet feeding member, the sheet feeding member is returned to the standby position,
a sheet feed motor configured to drive the sheet feed member to feed the sheet,
a moving mechanism configured to move the sheet feeding member between the standby position and the sheet feeding position by a drive of the sheet feed motor,
a position detector, operable to output a detection signal based on a position of the sheet feeding member, and
a lifter mechanism which is configured to lift the sheet stacking member towards the sheet feeding member, the lifter mechanism lifts
the sheet stacking member based on detection of the position detector, such that an the upper surface of the topmost stacked sheet is moved to a sheet-feeding position,
wherein when a first sheet feeding operation of the sheet feeding member starts after sheets are set on the sheet stacking member in a lower position, the sheet feed motor rotates by a predetermined amount and stops so that the sheet feeding member is lowered from the standby position towards the sheet feeding position by the moving mechanism in a state that the sheet stacking member is in the lower position, and
wherein when the sheet feeding member is lowered from the standby position towards the sheet feeding position in the first sheet feeding operation, the sheet stacking member is lifted by the lifter mechanism based on detection of the position detector so that the upper surface of the sheet stacked on the sheet stacking member is moved to the sheet-feeding position, and
an image forming portion which forms an image on a fed sheet.

8 more elements

A sheet feeding apparatus comprising

a sheet cassette which is pulled out from and to be attached to a body of the apparatus;
a sheet stacking member, provided on the sheet cassette, configured to stack sheets,
a sheet feeding member which is moveable between a standby position in a sheet feeding standby state and a sheet feeding position below the standby position, and which is configured to engage with an upper surface of a topmost sheet of the sheets stacked on the sheet stacking member to feed the sheet at the sheet feeding position, and in a middle of the sheet feeding operation of the sheet feeding member, the sheet feeding member is returned to the standby position,
a sheet feed motor configured to drive the sheet feed member to feed the sheet,
a moving mechanism configured to move the sheet feeding member between the standby position and the sheet feeding position by a drive of the sheet feed motor,
a position detector, operable to output a detection signal based on a position of the sheet feeding member,
a cassette detector operable to output a detection signal based on an attachment of the sheet cassette to the body of the apparatus, and
a lifter mechanism which is configured to lift the sheet stacking member towards the sheet feeding member, the lifter mechanism lifts the sheet stacking member based on detection of the position detector, such that the upper surface of the topmost sheet is moved to the sheet feeding position,
wherein when the cassette detector outputs the detection signal based on an attachment of the sheet cassette to the body of the apparatus, the sheet feed motor rotates by a predetermined amount and stops so that the sheet feeding member is lowered from the standby position towards the sheet feeding position by the moving mechanism in a state that the sheet stacking member is in the lower position, and
wherein when the sheet feeding member is lowered from the standby position towards the sheet feeding position in the first sheet feeding operation, the sheet stacking member is lifted by the lifter mechanism based on detection of the position detector so that the upper surface of the sheet stacked on the sheet stacking member is moved to the sheet feeding position.

7 more elements

An image forming apparatus which feeds a sheet and forms an image, comprising

a sheet feeding apparatus comprising
a sheet cassette which is pulled out from and to be attached to a body of the apparatus;
a sheet stacking member, provided on the sheet cassette, configured to stack sheets,
a sheet feeding member which is moveable between a standby position in a sheet feeding standby state and a sheet feeding position below the standby position, and which is configured to engage with an upper surface of a topmost sheet of the sheets stacked on the sheet stacking member to feed the sheet at the feeding position, and in a middle of the sheet feeding operation of the sheet feeding member, the sheet feeding member is returned to the standby position,
a sheet feed motor configured to drive the sheet feed member to feed the sheet,
a moving mechanism configured to move the sheet feeding member between the standby position and the sheet feeding position by a drive of the sheet feed motor,
a position detector, operable to output a detection signal based on a position of the sheet feeding member,
a cassette detector operable to output a detection signal based on an attachment of the sheet cassette to the body of the apparatus, and
a lifter mechanism which is configured to lift the sheet stacking member towards the sheet feeding member, the lifter mechanism lifts the sheet stacking member based on detection of the position detector, such that the upper surface of the topmost stacked sheet is moved to a sheet feeding position,
wherein when the cassette detector outputs the detection signal based on an attachment of the sheet cassette to the body of the apparatus, the sheet feed motor rotates by a predetermined amount and stops so that the sheet feeding member is lowered from the standby position towards the sheet feeding position by the moving mechanism in a state that the sheet stacking member is in the lower position, and
wherein when the sheet feeding member is lowered from the standby position towards the sheet feeding position in the first sheet feeding operation, the sheet stacking member is lifted by the lifter mechanism based on detection of the position detector so that the upper surface of the sheet stacked on the sheet stacking member is moved to the sheet feeding position, and
an image forming portion which forms an image on a fed sheet.

9 more elements

Dependencies are inferred from the claim text.

Facts

Application: 12/202,490Filed 2 Sep 2008
Priority: JP 2007-2322607 Sep 2007
Published: US 2009/0066009 A112 Mar 2009
Granted: 5 Jul 2011
Term ends: Not estimatedThe source records don’t support an estimate.

Classification11 codes

B65H 3/0684
Rollers or like rotary separators: on moving support, e.g. pivoting, for bringing the roller or like rotary separator into contact with the pile
B65H 1/14
With means for advancing the articles to present the articles to the separating device: comprising positively-acting mechanical devices
B65H 1/18
With means for advancing the articles to present the articles to the separating device: controlled by height of pile
B65H 7/04
By feelers or detectors: responsive to absence of articles, e.g. exhaustion of pile