Sheet feeding apparatus and image forming apparatus with sheet feeding apparatus therein

• US 20060269349A1
• Filed: 05/22/2006
• Published: 11/30/2006
• Est. Priority Date: 05/25/2005
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Iwase, Masaki, Matsushima, Akira, Uchida, Yashiro, Kawanishi, Minoru
• Granted Patent: US 7,753,366 B2
• Time in Patent Office: Days
• US Class Current: 400/625
• CPC Class Codes: B65H 1/18 controlled by height of pile
• CPC Class Codes: B65H 2511/22 Distance
• CPC Class Codes: B65H 2515/10 Mass, e.g. mass flow rate; Weight; Inertia
• CPC Class Codes: B65H 2555/25 D.C. motors, e.g. shunt motors
• CPC Class Codes: B65H 2601/22 Gravity effects, e.g. effect of weight of handled material

Abstract

The sheet feeding apparatus includes a sheet stack tray on which sheets to be fed are stacked, a drive motor for moving up the sheet stack tray, a detection sensor for detecting the position of an uppermost sheet stacked on the sheet stack tray, and a control part for controlling the function of the drive motor, wherein, when the detection sensor detects that the uppermost sheet reaches a predetermined height while the drive motor executes a drive so as to move up the sheet stack tray, the control part tentatively stops or decelerates the drive motor and thereafter drives the drive motor so as to move up the sheet stacked on the sheet stack tray to a feed position.

Claims

1. A sheet feeding apparatus comprising:

a sheet stack tray movable up and down, wherein sheets to be fed are stacked on said sheet stack tray;

a drive motor for moving said sheet stack tray up;

a detection sensor for detecting a position of an uppermost sheet stacked on said sheet stack tray; and

a control part for controlling a function of the drive motor based on a result of detection by said detection sensor;

wherein, when the detection sensor detects that the uppermost sheet reaches a predetermined height while the drive motor drives to move said sheet stack tray up, said control part effects a tentative stop or a speed reduction of said drive motor and, after the tentative stop or the speed reduction, drives said drive motor to move up said sheet stacked on the sheet stack tray to a feed position.

2. A sheet feeding apparatus according to claim 1, further comprising:

a height detection sensor for detecting that the sheet stacked on the sheet stack tray reaches the feed position.

3. A sheet feeding apparatus according to claim 2, wherein said control part effects a tentatively stop of the drive motor when the detection sensor detects that the uppermost sheet reaches the predetermined height, and, after the tentative stop, re-drives the drive motor so as to move up the sheet stack tray until the height detection sensor detects that the sheet stacked on the sheet stack tray reaches the feed position, but does not re-drive the drive motor in case, at the tentative stop of the drive motor in response to the detection by the detection sensor that the uppermost sheet reaches the predetermined height, the sheet on the sheet stack tray reaches the feed position.

4. A sheet feeding apparatus according to claim 1, wherein the detection sensor serves also as a sensor for detecting that a sheet is present on the sheet stack tray.

5. A sheet feeding apparatus according to claim 1, wherein said control part effects a tentatively stop of the drive motor when the detection sensor detects that the uppermost sheet reaches the predetermined height, and, after maintaining the drive motor in the stopped state for a predetermined period, re-drives the drive motor to move up the sheet on the sheet stack tray to the feed position.

6. A sheet feeding apparatus according to claim 5, wherein the predetermined period is a period required by the drive motor to completely stop.

7. A sheet feeding apparatus according to claim 1, wherein the sheet stack tray is provided in a sheet cassette detachably mounted in a main body of an apparatus;

and

in case, when the sheet cassette is mounted on the main body of the apparatus, the detection sensor detects that the uppermost sheet is in a position higher than the predetermined height, the control part controls the drive motor so as to move the sheet on the sheet stack tray to the feed position.

8. A sheet feeding apparatus according to claim 1, further comprising:

a detection flag of which a position is detected by the detection sensor and which is moved in contact with an upper surface of the sheet on the sheet stack tray, wherein the detection flag, in the presence of a sheet on the sheet stack tray, comes into contact with the sheet when the uppermost sheet becomes positioned higher than the predetermined height by a move-up of the sheet stack tray thereby being so moved as to switch an on/off state of the detection sensor, but, in the absence of a sheet on the sheet stack tray, does not move so as to switch the on/off state of the detection sensor when the sheet stack tray is moved up;

a height detection sensor for detecting that the sheet on the sheet stack tray reaches the feed position;

a height detection flag moved in contact with an upper surface of a sheet on the sheet stack tray or an upper surface of the sheet stack tray thereby switching an on/off state of the height detection sensor, wherein the detection flag, in the presence of a sheet on the sheet stack tray, comes into contact with the sheet when the uppermost sheet reaches the feed position by a move-up of the sheet stack tray thereby being so moved as to switch an on/off state of the detection sensor, but, in the absence of a sheet on the sheet stack tray, comes into contact with the sheet stack tray thereby switching an on/off state of the height detection sensor; and

a notifying part for notifying absence of a sheet on the sheet stack tray, in case the on/off state of the detection sensor does not change but the on/off state of the height detection sensor changes by moving the sheet stack tray up.