Sheet feeding and separating apparatus with stack force relief/enhancement

• US 4,561,644 A
• Filed: 09/21/1982
• Issued: 12/31/1985
• Est. Priority Date: 09/21/1982
• Status: Expired due to Term

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Clausing, Don P.
• Primary Examiner(s): Stoner, Jr., Bruce H.
• Assistant Examiner(s): Carroll, John A.
• Application Number:
  US06/420,964
• Time in Patent Office: 1,197 Days
• Field of Search: 271/10, 271/34, 271/35, 271/121, 271/122, 271/124, 271/125, 271/110, 271/111, 271/117, 271/118
• US Class Current: 271/34
• CPC Class Codes: B65H 2601/25 Damages to handled material
• CPC Class Codes: B65H 7/125 sensing the double feed or separation without contacting the articles
• CPC Class Codes: G03G 15/6529 Transporting G03G15/6555 takes precedence

Abstract

A retard feeder and separator apparatus includes a sensor located at a retard nip downstream from a portion of a feed belt that applies a normal force to a stack of sheets and forwards sheets individually from the stack. The sensor detects the lead edge of a sheet fed from the stack and simultaneously causes relief of the normal force against the stack in order to reduce multifeeds and sheet damage. Alternatively, if the sensor does not sense a sheet within a predetermined time the normal force against the stack will be increased to reduce misfeeding.

Claims

1. A high speed sheet feeding and separating apparatus for feeding and separating individual sheets from a stack of sheets, comprising the combination of:

an endless feeding and separating belt mounted for sheet feeding engagement with the front edge of the stack of sheets and applying a normal force thereto;

said feed belt being rotatably mounted between spaced supports to provide a deformable continuously unsupported section between said spaced supports;

a retard member having a supported curved frictional retard surface, said retard surface deformably engaging said feed belt in said unsupported section of said feed belt to form therewith a correspondingly curved separating retard nip in which said retard surface and said belt are continuously biased against one another;

a normal force relief means for automatically changing said normal force of said feed belt against the front edge of the stack while said feed belt continues maintaining contact with the stack of sheets, including a sensor positioned to one side of said separating retard nip and adapted to signal the presence or absence of a sheet as it comes into said separating retard nip; and

control means which in response to a signal from said stack force relief means will decrease the stack normal force of said feed belt against the stack of sheets if a sheet is present at said separating retard nip, and increase the stack normal force of said feed belt against the stack if a sheet is not present within a predetermined time at said separating retard nip.

2. The improvement of claim 1, wherein said retard member is a frictional surfaced roll.

3. A dual mode feeding and separating apparatus, comprising:

a support means for supporting a stack of sheets to be fed individually from said stack of sheets;

a feed belt mounted to apply a normal force to the front edge of said stack of sheets, said feed belt being rotatably mounted between spaced supports to provide a deformable unsupported section therebetween;

a retard member positioned within said unsupported section and having a curved surface that deformably engages said feed belt to form a separation nip therewith;

sensor means positioned on one side of said separation nip and adapted to sense the presence or absence of a sheet within said separation nip; and

actuator means adapted to act in a first mode in response to a signal from said sensor means indicating that a sheet is present at said separation nip to relieve the normal force of said feed belt against said front edge of said stack of sheets and act in a second mode to increase the normal force of said feed belt against said front edge of said stack of sheets if a sheet is not sensed by said sensor means at said separation station within a predetermined time all the while maintaining feed belt contact with the front edge of said stack of sheets.

4. A sheet feeder adapted to feed a wide variety of sheets individually from a stack, comprising:

a feed belt mounted in sheet feeding engagement with the front edge of the stack with a predetermined normal force;

retard means mounted in a free span section of said feed belt and forming a retard nip with said feed belt;

sensor means positioned on one side of said retard nip of said retard means for sensing the presence of a sheet at said retard nip; and

actuator means responsive to a signal from said sensor means to simultaneously relieve the engagement of said feed belt against the front edge of said stack in order to increase the range of weights of sheets that can be fed from the stack while maintaining contact of said feed belt with the front edge of the stack.

5. The feeder of claim 4, wherein absent a signal from said sensor means to said actuator means said feed belt assumes its original engagement normal force against the stack in order to insure the feeding of a sheet to said retard nip.

6. A method for feeding and separating a wide variety of sheets individually from a stack of sheets, comprising the steps of:

a. providing a feed means on top of the front edge of the stack with said feed means applying a predetermined normal force to said stack and feeding a first sheet from said stack to a retard nip;

b. sensing at one side of said retard nip for the presence of the sheet; and

c. moving said feed means in order to relieve the normal force of said feed means against the front edge of said stack once the presence of a sheet at said retard nip is sensed with said feed means continuing to contact said stack before and after said normal force has been relieved.

7. A method for feeding and separating a wide variety of sheets individually from a stack of sheets, comprising the steps of:

a. providing a feed means on top of the front edge of the stack with said feed means applying a predetermined normal force to said stack and feeding a sheet from said stack to a retard nip;

b. sensing the presence of the sheet as it comes into said retard nip with a sensor positioned on one side of said retard nip;

c. moving said feed means in order to relieve the normal force of said feed means against the front edge of said stack once the presence of a sheet at said retard nip is sensed with said feed means all the while continuing to contact said stack before and after said normal force has been relieved;

d. feeding a second sheet from said stack; and

e. increasing the normal force of said feed means against the front edge of said stack if the second sheet is not sensed at said retard nip within a predetermined time.

8. A sheet feeder adapted to feed a wide variety of sheets individually from a stack, comprising in combination:

a feed means for feeding sheets from the stack;

retard means for separating sheets received from said feed means;

sensor means positioned on one side of said retard means for sensing the presence of a sheet as it enters said retard means; and

actuator means responsive to a signal from said sensor means to relieve the engagement of said feed means against the front edge of the stack in order to increase the range in weights of sheets that can be fed from the stack while maintaining contact of said feed means with the front edge of the stack.

9. A sheet feeding and separating apparatus adapted to feed and separate individual sheets from a stack of sheets, comprising in combination:

an endless feed belt mounted for sheet feeding engagement with the front edge of the stack of sheets and applying a normal force thereto;

said feed belt being rotatably mounted between spaced supports to provide a deformable unsupported section therebetween;

a retard member having a supported curved frictional retard surface deformably engaging said feed belt in said unsupported section of said feed belt to form therewith a corresponding curved separating retard nip in which said retard surface and said belt are continuously biased against one another;

stack force relief sensor means mounted to one side of said separating retard nip and adapted to signal the presence or absence of a sheet once it enters said separating retard nip;

a pivotably mounted frame member, said frame member adapted for supporting said feed belt, said retard member and said stack force relief sensor means;

stack height sensor means adapted to initiate movement of said feed belt toward said stack of sheets whenever the normal force of said feed belt against the front edge of said stack of sheets is less than a predetermined amount; and

actuator means for changing the normal force of said feed belt against the front edge of said stack including a solenoid adapted to be actuated once a signal is received from said stack force relief sensor means to pivot said frame and reduce the pressure of said feed belt against the front edge of said stack of sheets to a minimum value while continuing to maintain feed belt contact with the front edge of said stack of sheets.