DRIVE SWITCHING MECHANISM AND FEEDING DEVICE

• US 20100032887A1
• Filed: 08/05/2009
• Published: 02/11/2010
• Est. Priority Date: 08/07/2008
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Morinaga, Kazuyuki
• Granted Patent: US 8,292,288 B2
• Time in Patent Office: Days
• US Class Current: 271/10.120
• CPC Class Codes: B65H 2403/421 involving at least a gear with toothless portion
• CPC Class Codes: B65H 2403/481 Planetary
• CPC Class Codes: B65H 2403/5332 with rotating slotted link
• CPC Class Codes: B65H 3/0661 for separating inclined-stacked articles with separator rollers above the stack
• CPC Class Codes: B65H 3/0669 Driving devices therefor
• CPC Class Codes: F16H 3/40 Gearings for reversal only

Abstract

A drive switching mechanism includes a transmission gear and a planetary gear configured to transmit a drive from an input gear to an output gear. The drive switching mechanism further includes a swinging member configured to hold the planetary gear such that the planetary gear can swing around the input gear, a retaining unit configured to retain the swinging member in a swing enabled or disabled state, and a releasing unit configured to disengage the planetary gear from the output gear and cause them to be spaced apart. The output gear includes a toothless part that does not engage with a gear section engaging with the transmission gear.

Claims

1. A drive switching mechanism for switching between transmission and non-transmission of a driving force of a drive motor from an input gear to an output gear, the drive switching mechanism comprising:

a transmission gear configured to transmit a drive from the input gear to the output gear;

a planetary gear configured to transmit a drive from the input gear to the output gear;

a swinging member configured to hold the planetary gear such that the planetary gear can swing around the input gear and can engage with the output gear;

a retaining unit configured to retain the swinging member in either one of a state in which the swinging member can swing and a state in which the output gear and the planetary gear are not engaged; and

a releasing unit configured to disengage the planetary gear and the output gear and cause them to be spaced apart from each other,

wherein the output gear includes a toothless part that does not engage with the transmission gear and that does not receive a drive from the transmission gear,

the retaining unit retains the swinging member such that the swinging member can swing in a state in which the transmission gear and the output gear are disengaged by the toothless part,

driving the drive motor causes the output gear and the planetary gear to engage with each other and rotates the output gear, and

after the toothless part is passed and the transmission gear and the output gear become engaged, the releasing unit disengages the planetary gear and the output gear.

2. The drive switching mechanism according to claim 1, wherein the output gear includes a cam section,

the swinging member includes a cam follower section, and

the cam section and the cam follower section constitute the releasing unit.

3. The drive switching mechanism according to claim 1, wherein, in a state where the planetary gear and the output gear are disengaged by the releasing unit, the retaining unit retains the planetary gear and the output gear in the disengaged state.

4. The drive switching mechanism according to claim 1, wherein a first reduction ratio from the input gear to the output gear through the planetary gear is smaller than a second reduction ratio from the input gear to the output gear through the transmission gear.

5. The drive switching mechanism according to claim 1, further comprising an urging member configured to apply an urging force for rotating the output gear by an angle required for separating a gear tip of the output gear and a gear tip of an end of the toothless part when the transmission gear reaches the toothless part.

6. A feeding device for separating and conveying recording sheets stacked on a stacking portion one by one, the feeding device comprising:

a driving motor;

a feeding roller configured to convey a recording sheet;

a pressing plate on which a plurality of recording sheets can be stacked;

an urging unit configured to urge the pressing plate against the feeding roller;

a control cam configured to cause the pressing plate to swing between a position at which a recording sheet on the pressing plate is pressed into contact with the feeding roller and a position at which the recording sheet is spaced apart from the feeding roller;

a control-cam driving gear configured to drive the control cam; and

a drive transmitting unit configured to transmit a driving force from the driving motor to the control-cam driving gear through a plurality of gears,

the drive transmitting unit comprising;

a sun gear configured to receive a driving force from the driving motor;

a transmission gear configured to transmit a drive from the sun gear to the control-cam driving gear;

a planetary gear configured to transmit a drive from the sun gear to the control-cam driving gear;

a swinging member configured to hold the planetary gear such that the planetary gear can swing around the sun gear and engage with the control-cam driving gear;

a retaining unit configured to retain the swinging member in either one of a state in which the swinging member can swing and a state in which the control-cam driving gear and the planetary gear are not engaged; and

a releasing unit configured to disengage the planetary gear and the control-cam driving gear and cause them to be spaced apart from each other,

wherein the retaining unit is formed of at least a fit section disposed in the swinging member and a lever member that can be fit in the fit section,

the releasing unit is formed of at least a cam surface disposed in the control-cam driving gear and a cam follower section disposed in the swinging member so as to be able to engage with the cam surface,

the control-cam driving gear includes a toothless part that does not engage with the transmission gear and that is incapable of transmitting a drive,

the retaining unit brings the swinging member to the state in which the swinging member can swing from a state in which the transmission gear and the control-cam driving gear are disengaged by the toothless part, and driving the drive motor causes the control-cam driving gear and the planetary gear to engage with each other and rotates the control-cam driving gear, and

after the toothless part is passed and the transmission gear and the control-cam driving gear become engaged, the releasing unit disengages the planetary gear and the control-cam driving gear.

7. The feeding device according to claim 6, wherein the urging unit applies the urging force so as to rotate the control-cam driving gear in a direction in which the toothless part further advances when the transmission gear reaches the toothless part of the control-cam driving gear.

8. The feeding device according to claim 6, further comprising a conveying roller set including a conveying roller and a driven roller opposed to and pressed into contact with the conveying roller, the conveying roller set pinching and conveying a recording sheet,

wherein the driving motor drives the conveying roller so as to rotate the conveying roller,

the feeding device is operable in a first conveying mode, a second conveying mode, and a third conveying mode,

in the first conveying mode, a recording sheet is conveyed by both the conveying roller and the feeding roller being rotated in a conveying direction,

in the second conveying mode, a recording sheet is conveyed by both the conveying roller and the feeding roller being rotated in the conveying direction after the conveying roller is rotated in a reversed direction, the feeding roller is rotated in the conveying direction, a front end of the recording sheet is brought into contact with a tangent line of the conveying roller set, and the front end is aligned therewith, and

in the third conveying mode, a recording sheet is conveyed by both the conveying roller and the feeding roller being rotated in the conveying direction after the recording sheet is conveyed by the conveying roller and the feeding roller in the conveying direction, a front end of the recording sheet is pinched by the conveying roller set, then the conveying roller is rotated in the reversed direction, the feeding roller is stopped, the front end of the recording sheet is sent back to the tangent line of the conveying roller set, and the front end is aligned with the tangent line.