Pick mechanism with stack height dependent force for use in an image forming device

• US 7,594,647 B2
• Filed: 09/08/2005
• Issued: 09/29/2009
• Est. Priority Date: 09/08/2005
• Status: Expired due to Fees

• Current Assignee: Lexmark International Incorporated (Ninestar Corporation)
• Original Assignee: Lexmark International Incorporated (Ninestar Corporation)
• Inventors: DeVore, Benjamin C., Gettelfinger, Darin M., Horrall, Paul Douglas
• Primary Examiner(s): Mackey; Patrick H
• Assistant Examiner(s): McCullough; Michael C
• Application Number:
  US11/221,506
• Publication Number:
  US 20070052153A1
• Time in Patent Office: 1,482 Days
• Field of Search: 271/10.09, 271/21, 271/109, 271/117
• US Class Current: 271/10.09
• CPC Class Codes: B65H 2220/01 indicating an entity as a function of which control, adjustment or change is performed, i.e. input
• CPC Class Codes: B65H 2220/02 indicating an entity which is controlled, adjusted or changed by a control process, i.e. output
• CPC Class Codes: B65H 2220/08 for distinguishing changing an entity in function of another entity purely by mechanical means, i.e. no electronics involved
• CPC Class Codes: B65H 2301/423245 the pile lying on a stationary support, i.e. the separator moving according to the decreasing height of the pile
• CPC Class Codes: B65H 2511/15 Height, e.g. of stack
• CPC Class Codes: B65H 2515/34 Pressure, e.g. fluid pressure
• CPC Class Codes: B65H 3/06 Rollers or like rotary separators B65H3/42 takes precedence

Abstract

Embodiments of a pick mechanism for use in an image forming device. In one embodiment, a first mechanism individually moves each of the media sheets from a stack in the input area thereby gradually decreasing a height of the stack. The first mechanism applies a first force profile to the stack while individually moving each of the plurality of media sheets. As the media sheets are moved, the height of the stack gradually decreases from a first height to a second height. As the stack decreases below the second height, a second force profile is applied to the stack. The second force profile is different from the first profile. The first and second force profiles prevent slip as the media sheets are fed from the input area, and also prevent double sheet feeds.

Claims

1. A device to move media sheets within an image forming apparatus, the device comprising:

an input area sized to hold a stack of the media sheets, the input area including a support floor;

an arm having a moveable first end and a second end, the arm pivotally connected to the image forming apparatus adjacent to the second end with the second end spaced a fixed distance from the support floor and being spaced a greater distance from the support floor than the movable first end such that the arm forms acute angles with the support floor, the arm applying a downward force to the stack;

a roller operatively connected to the movable first end of the arm and positioned to remain in contact with a top-most media sheet of the stack to individually move each of the media sheets from the input area;

a mechanism including a first end connected to the arm and a second end connected to the image forming apparatus, the mechanism operable in;

a first state corresponding to the first end of the arm being positioned above a predetermined height in the device such that the distance between the first and the second ends of the mechanism is less than a predetermined length and the mechanism provides substantially no upward forces on the arm;

a second state corresponding to the first end of the arm being positioned at the predetermined height in the device such that the distance between the first and second ends of the mechanism being substantially equal to the predetermined length such that the mechanism engages the arm to exert a counterbalance force on the arm of a first force amount; and

a third state corresponding to the first end of the arm being positioned below the predetermined height in the device and the and the distance between the first and the second ends of the mechanism being greater than the predetermined length such that the mechanism engages the arm to exert the counterbalance force on the arm of an amount greater than the first force amount,

the arm and mechanism exerting an overall downward force to media sheets in the input area at a first overall force amount while the mechanism is in the first state, and at a second overall force amount that is less than the first overall force amount while the mechanism is in the second and third states, the overall downward force gradually decreasing as the first end of the arm decreases from the predetermined height, the predetermined height corresponding to a height of a stack of media sheets that is less than a maximum number of sheets maintained in the input area.

2. The device of claim 1, wherein the arm further comprises a gear train that transfers rotational power from a motor within the image forming apparatus to the roller.

3. The device of claim 1, wherein the overall downward force applied to the media sheets decreases in a linear manner.

4. The device of claim 1, wherein the overall downward force applied to the media sheets is constant when the stack is above the predetermined height.

5. The device of claim 1, wherein an overall downward force is 50 grams when the media stack is above the predetermined height.

6. A device to move media sheets within an image forming apparatus, the device comprising:

an input area sized to hold a stack of the media sheets, the input area including a support floor;

an arm including a first end and a second end, the second end being fixedly attached to the image forming apparatus with the arm configured to pivot about the second end with the first end remaining in contact with a top-most sheet of the stack as the stack is depleted; and

a biasing mechanism including a first end connected to the arm and a second end connected to the image forming apparatus, the biasing mechanism exerting substantially no force on the arm while the first end of the arm is above a first height in the image forming apparatus and exerts a non-zero force on the arm while the first end thereof is at or below the first height, the non-zero force gradually increasing as a distance between the first height and the first end of the arm increases such that the overall force applied to a stack of media in the input area gradually decreases as the distance increases, the first height corresponding to a height of the stack of media sheets that is less than a maximum amount that can be maintained in the input area.

7. The device of claim 6, wherein an overall force applied to the stack is constant while the stack decreases from the maximum amount to the first height.

8. The device of claim 6, wherein the arm further comprises a rotating roller, the roller contacting the top-most sheet and rotating to move the top-most out of the input area.

9. The device of claim 6, wherein the biasing mechanism comprises a spring that is attached to the arm and applies an upward force to the arm.

10. A device to move media sheets within an image forming apparatus, the device comprising:

an input area sized to hold a stack of the media sheets, the input area including a support floor;

an arm including a first end that includes a roller and a second end that is connected to the image forming apparatus, the arm being able to pivot about the second end with the roller positioned to remain in with a top-most sheet of the stack as the stack is depleted, the second end remaining positioned a greater distance from the support floor than the first end as the arm pivots about the second end; and

a biasing mechanism including a first end connected to the arm and a second end connected to the image forming device, the biasing mechanism positionable between a disengaged orientation with the first and second ends positioned less than a predetermined distance apart with the biasing mechanism in a non-stretched configuration, and an engaged orientation with the first and second ends positioned greater than the predetermined distance apart with the biasing mechanism in a stretched configuration;

wherein the biasing mechanism is in the disengaged orientation while the first end of the arm is above a predetermined height in the device and applies substantially no force on the arm, and is in the engaged orientation while the first end of the arm is at or below the predetermined height and applies a force on the arm, the applied force increasing as a distance between the predetermined height and a position of the first end of the arm increases, the predetermined height corresponding to stack of media sheets that is less than a maximum amount that can be maintained in the input area.