Claims
- 1. A sheet feeding apparatus for transferring a sheet from a stack to a sheet path, comprising:
- (a) a feeder means capable of exerting a selectively variable drive force against a sheet in a direction toward a sheet path;
- (b) a normal force relief means coupled to said feeder means for changing the selectively variable drive force exerted by said feeder means;
- (c) a data store associating a value of a selected characteristic of a sheet with a setting for said normal force relief means; and
- (d) a controller coupled to said normal force relief means and said data store, said controller adapted to determine a value for the selected characteristic of a sheet to be transferred, retrieve a corresponding setting for said normal force relief means from said data store, and manipulate said normal force relief means to said corresponding setting, wherein said controller recognizes a misfeed condition when a length of time between initiation of a sheet transfer operation and a transfer of a sheet by said feeder means exceeds a predetermined time period, said controller being adapted to correct the misfeed condition by manipulating said normal force relief means to increase the selectively variable drive force.
- 2. A sheet feeding apparatus for transferring a sheet from a stack to a sheet path, comprising:
- (a) a feeder means capable of exerting a selectively variable drive force against a sheet in a direction toward a sheet path;
- (b) a normal force relief means coupled to said feeder means for changing the selectively variable drive force exerted by said feeder means;
- (c) a data store associating a value of a selected characteristic of a sheet with a setting for said normal force relief means; and
- (d) a controller coupled to said normal force relief means and said data store, said controller adapted to determine a value for the selected characteristic of a sheet to be transferred, retrieve a corresponding setting for said normal force relief means from said data store, and manipulate said normal force relief means to said corresponding setting, wherein said controller recognizes a multifeed condition when more than one sheet is present at said feeder means, said controller being adapted to correct the multifeed condition by manipulating said normal force relief means to decrease the selectively variable drive force.
- 3. The sheet feeding apparatus of claim 2 further comprising a user interface coupled to said controller for entry of a value for the selected characteristic of a sheet to be transferred.
- 4. The sheet feeding apparatus of claim 3 wherein said data store associates an increment for adjusting said normal force relief means with a value for the selected characteristic of a sheet.
- 5. The sheet feeding apparatus of claim 4 wherein said controller is capable of updating a setting for said normal force relief means maintained in said data store.
- 6. A sheet feeding apparatus for transferring a sheet in a photocopying device, comprising:
- (a) a feeder means for urging a sheet toward a sheet path by exerting a drive force against the sheet;
- (b) a retard means for preventing an additional sheet from being simultaneously driven toward the sheet path by said feeder means, said retard means in communication with said feeder means and acting with said feeder means to exert a combined drive force against the sheet;
- (c) a normal force relief means coupled to said retard means for selectively altering the combined drive force;.
- (d) a data store for associating a value for a selected characteristic of a sheet with an initial setting for said normal force relief means and an increment for selectively altering the combined drive force;.
- (e) a controller coupled to said normal force relief means and said data store, said controller adapted to determine a value for said selected characteristic of a sheet to be transferred, retrieve a corresponding initial setting for said normal force relief means from said data store, and cause said normal force relief means to assume said corresponding initial setting;
- (f) a misfeed sensor coupled to said controller and adapted to signal said controller when said feeder means transfers a sheet; and
- (g) a sensor coupled to said controller for evaluating said selected characteristic of a sheet to be transferred, said controller capable of altering the combined drive force in response to a signal from said sensor,
- wherein said controller recognizes a misfeed condition when a length of time between initiation of a sheet transfer operation and receipt of a signal from said misfeed sensor exceeds a predetermined time period, said controller adapted to correct said misfeed condition by increasing the combined drive force.
- 7. The sheet feeding apparatus of claim 6 wherein said controller recognizes a multifeed condition when more than one sheet is present at said retard means, said controller adapted to correct the multifeed condition by causing said normal force relief means to decrease the combined drive force.
- 8. The sheet feeding apparatus of claim 7 wherein said retard means comprises a roll mounted on a shaft equipped with a slip clutch, said roll adapted to rotate in a direction opposite that of said feeder means when more than one sheet is present between said feeder means and said retard means.
- 9. The sheet feeding apparatus of claim 8 further comprising a motion sensor coupled to said controller and adapted to signal said controller when said roll of said retard means rotates in a direction opposite that of said feeder means.
- 10. The sheet feeding apparatus of claim 8 wherein said retard means comprises a non-rotatable roll for preventing more than one sheet from passing between said feeder means and said retard means.
- 11. A sheet feeding apparatus for transferring successive sheets from a sheet stack to a sheet path in a photocopying device, comprising:
- (a) a feeder means for urging sheets from the sheet stack in a direction toward the sheet path;
- (b) a retard means for preventing multiple sheets from being simultaneously driven toward the sheet path by said feeder means, said retard means acting with said feeder means to exert a combined drive force against a sheet at a retard nip formed by a junction of said feeder means and said retard means;
- (c) a normal force relief means coupled to said retard means for selectively altering said combined drive force;
- (d) a means for establishing an initial combined drive force for feeding a first sheet toward the sheet path;
- (e) a data store for associating a selected characteristic of a sheet with an increment for selectively altering said combined drive force;
- (f) a misfeed sensor for detecting a sheet as it passes through said retard nip; and
- (g) a microprocessor controller capable of establishing said initial combined drive force prior to transferring a sheet and dynamically altering said combined drive force by an increment associated with said selected characteristic,
- wherein said controller recognizes a misfeed condition when a length of time between initiation of a sheet transfer operation and detection of a sheet by said misfeed sensor exceeds a predetermined time period, said controller adapted to correct the misfeed condition by causing said normal force relief means to increase said combined drive force.
- 12. The sheet feeding apparatus of claim 11 wherein said controller recognizes a multifeed condition when more than one sheet is present at said retard nip, said controller adapted to correct the multifeed condition by causing said normal force relief means to decrease said combined drive force.
- 13. The sheet feeding apparatus of claim 12 wherein said normal force relief means comprises a spring loading mechanism coupled to means for raising or lowering said spring loading mechanism.
- 14. The sheet feeding apparatus of claim 13 wherein said data store comprises a lookup table stored in a memory coupled to said microprocessor controller.
- 15. The sheet feeding apparatus of claim 14 wherein said selected characteristic of a sheet comprises sheet weight.
- 16. The sheet feeding apparatus of claim 11 further comprising a user interface for entry of an initial value for said selected characteristic of a sheet to be transferred.
- 17. A method of transferring sheets in a photocopying device, comprising the steps of:
- (a) determining a value for a selected characteristic of a sheet to be transferred;
- (b) setting an initial drive force of a sheet transfer means, said initial drive force corresponding to said value for said selected characteristic;
- (c) initiating a sheet transfer operation;
- (d) determining whether said sheet transfer means successfully transfers a sheet; and
- (f) adjusting said initial drive force by an amount corresponding to said selected characteristic if the sheet is not successfully transferred, wherein said adjustment comprises increasing said initial drive force if the sheet is not successfully transferred within a predetermined time period.
- 18. A method of transferring sheets in a photocopying device, comprising the steps of:
- (a) determining a value for a selected characteristic of a sheet to be transferred;
- (b) setting an initial drive force of a sheet transfer means, said initial drive force corresponding to said value for said selected characteristic;
- (c) initiating a sheet transfer operation;
- (d) determining whether said sheet transfer means successfully transfers a sheet; and
- (f) adjusting said initial drive force by an amount corresponding to said selected characteristic if the sheet is not successfully transferred, wherein said adjustment comprises decreasing said initial drive force if said sheet transfer means attempts to simultaneously transfer more than one sheet.
Parent Case Info
This application is a continuation-in-part of application Ser. No. 07/983,933, filed on Dec. 1, 1992, now abandoned.
US Referenced Citations (4)
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Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
983933 |
Dec 1992 |
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