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

• US 20070052153A1
• Filed: 09/08/2005
• Published: 03/08/2007
• Est. Priority Date: 09/08/2005
• Status: Active Grant

• Current Assignee: Lexmark International Incorporated (Ninestar Corporation)
• Original Assignee: Lexmark International Incorporated (Ninestar Corporation)
• Inventors: Gettelfinger, Darin, Horrall, Paul, DeVore, Benjamin
• Granted Patent: US 7,594,647 B2
• Time in Patent Office: Days
• US Class Current: 271/117
• 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;

an arm having a first end and a second end, the arm pivotally connected to the image forming apparatus adjacent to the second end, the arm applying a downward force to the stack;

a roller operatively connected to the second 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 operatively connected to the arm to apply an upward force to the arm when the stack is below a predetermined height;

an overall downward force applied to the media sheets is greater when the stack is above the predetermined height, and the overall downward force applied to the media sheets gradually decreases as the height of the stack decreases below the predetermined height.

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 substantially constant when the stack is above the predetermined height.

5. The device of claim 1, wherein the mechanism comprises a biasing member having a first end and a second end and being positionable between an unengaged orientation and an engaged orientation, a distance between the first end and the second end being greater in the engaged orientation than in the unengaged orientation.

6. The device of claim 1, wherein an angle is formed between the arm and a top surface of the stack, the angle being less when the stack is above the predetermined height than when the stack is below the predetermined height.

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

8. 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;

an arm movably positioned within the image forming apparatus to remain in contact with a top-most sheet of the stack as the stack is depleted from a first height to a second height, the arm applying a force to the stack; and

a biasing mechanism operatively connected to the arm and positionable between a disengaged orientation that does not affect the force and an engaged orientation that lessens the force;

the biasing mechanism is in the disengaged orientation when the stack of media sheets decreases from the first height to the second height, the biasing mechanism is in the engaged orientation when the stack of media sheets decreases below the second height.

9. The device of claim 8, wherein the overall force applied by the arm is reduced as the stack decreases below the second height.

10. The device of claim 8, wherein the first height corresponds to the input area full of the media sheets.

11. The device of claim 8, wherein an overall force applied to the stack is substantially constant while the stack decreases from the first height to the second height.

12. The device of claim 8, wherein the arm is positioned to pivot into the input area and remain in contact with a top-most sheet of the stack.

13. The device of claim 12, 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.

14. The device of claim 12, wherein the biasing mechanism comprises a spring that is attached to the arm and applies an upward force to the arm.

15. A method of moving a plurality of media sheets from an input area within an image forming apparatus, the method comprising the steps of:

using a first mechanism and individually moving each of the plurality of media sheets from a stack in the input area thereby gradually decreasing a height of the stack;

applying a first force profile through the first mechanism to the stack while individually moving each of the plurality of media sheets as a height of the media sheets gradually decreases from a first height to a second height;

applying a second force profile to the stack through the first mechanism as the stack decreases below the second height; and

offsetting the second force profile with a force applied by a second mechanism as the stack decreases below the second height and causing an overall force to gradually decrease as the stack gradually decreases from the second height.

16. The method of claim 15, wherein the step of applying the first force profile through the first mechanism comprises applying a substantially constant downward force to the stack.

17. The method of claim 15, wherein the step of applying the second force profile through the first mechanism comprises applying a gradually increasing amount of downward force to the stack.

18. The method of claim 15, wherein the step of offsetting the second force profile with the force applied by a second mechanism comprises applying a downward force by the first mechanism and applying a lesser upward force by the second mechanism.

19. The method of claim 15, wherein the step of applying the first force profile occurs when the input area is substantially full of the media sheets.

20. The method of claim 15, wherein the step of applying the second force profile to the stack through the first mechanism comprises pivoting an arm that is in contact with a top-most media sheet of the stack downward into the input area and increasing an angle of the arm.