Feed roll wear compensation scheme

• US 5,342,037 A
• Filed: 12/17/1993
• Issued: 08/30/1994
• Est. Priority Date: 12/17/1993
• Status: Expired due to Term

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Martin, Kathleen M.
• Primary Examiner(s): SCHACHER, RICHARD
• Application Number:
  US08/168,288
• Time in Patent Office: 256 Days
• Field of Search: 271/110, 271/111, 271/121-125, 271/126, 271/127, 271/147
• US Class Current: 271/111
• 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 2220/03 indicating an entity which is measured, estimated, evaluated, calculated or determined but which does not constitute an entity which is adjusted or changed by the control process per se
• CPC Class Codes: B65H 2220/11 indicating that the input or output entities exclusively relate to machine elements
• CPC Class Codes: B65H 2511/14 Diameter, e.g. of roll or package
• CPC Class Codes: B65H 2511/15 Height, e.g. of stack
• CPC Class Codes: B65H 2513/11 angular
• CPC Class Codes: B65H 2513/51 Sequence of process
• CPC Class Codes: B65H 2601/25 Damages to handled material
• CPC Class Codes: B65H 3/06 Rollers or like rotary separators B65H3/42 takes precedence
• CPC Class Codes: B65H 5/062 between rollers or balls
• CPC Class Codes: B65H 7/02 by feelers or detectors

Abstract

A feed roll wear compensating method and apparatus measures the surface speed of the feed and nudger rolls that are rotated by a motor and adjusts the motor speed to prevent sheet damage from occurring. The surface speed of each of the rolls is measured by sensors that detect the position of a moving sheet and the signal from the sensors is used to deduce the reduction in diameter of the rolls due to wear. The roll wear information is used to adjust the nominal elevator height to maintain constant force on the sheets and to provide feedback for adaptive control of the feed motor to adjust the speed of the feed roll.

Claims

1. A roll wear compensation system for use in a friction retard feeder that feeds copy sheets from a stack, comprising:

a nudger roll and a feed roll, said feed roll forming a nip with a retard roll;

a motor for driving said nudger roll and feed roll;

an elevator adapted to maintain normal force of said nudger roll against the sheet stack;

a first sensor positioned downstream of said nudger roll and upstream of said feed roll and second a sensor downstream of said feed roll for signaling the arrival time of a copy sheet at each of said first and second sensors; and

a controller for calculating the time of travel of the copy sheet between said nudger roll and said first sensor and between said first sensor and said second sensor, measuring the diameter of both said nudger roll and said feed roll, comparing said measured diameters of said nudger roll and said feed roll with nominal diameters stored in a lookup table, and adjusting the nominal height of said elevator when the diameter of said nudger roll is less than a predetermined diameter and adjusting the roll speed of said feed roll when the diameter of said feed roll is less than a predetermined diameter in order to minimize sheet misfeeds and prevent tearing of copy sheets during transport through a paper path.

2. The roll wear compensation system of claim 1, wherein said controller signals a remote interactive control station when roll wear is indicated.

3. A method of compensating for roll wear in a feeder system that feeds sheets from a stack, comprising:

providing a nudger roll positioned above and in contact with the sheet stack and a feed roll for driving the sheets received from said nudger roll into a paper path;

providing a motor for driving said nudger roll and feed roll;

providing an elevator to support the sheet stack and maintain normal force of said nudger roll against the sheet stack;

providing a first sensor positioned downstream of said nudger roll and upstream of said feed roll and a second sensor downstream of said feed roll for signaling the arrival time of a sheet at each of said first and second sensors; and

measuring the arrival time of the lead edge of the sheet at said first sensor and at said second sensor;

calculating travel time of the sheet between said nudger roll and said first sensor and between said first sensor and said second sensor;

determining the roll speed of said nudger roll and said feed roll;

calculating the roll diameter of said nudger roll and said feed roll;

comparing the roll diameter of said nudger roll and said feed roll with nominal roll diameters; and

adjusting the nominal height of said elevator when the diameter of said nudger roll is less than the nominal diameter and adjusting said motor and thereby the roll speed of said feed roll when the diameter of said feed roll is less than the nominal diameter in order to minimize sheet misfeeds and prevent tearing of copy sheets during transport through the paper path.

4. In a reproduction system adapted to make copies of page image information by transferring the page image information to copy sheets fed from a copy sheet feeder, the improvement of roll wear compensation in the copy sheet feeder characterized by:

a nudger roll and a feed roll, said feed roll forming a nip with a retard roll;

a motor for driving said nudger roll and feed roll;

an elevator adapted to maintain normal force of said nudger roll against the sheet stack;

a first sensor means positioned downstream of said nudger roll and upstream of said feed roll and a second sensor downstream of said feed roll for signaling the arrival time of a copy sheet at each of said first and second sensor means; and

a controller for calculating the time of travel of the copy sheet between said nudger roll and said first sensor and between said first sensor and said second sensor, measuring the diameter of both said nudger roll and said feed roll, comparing said measured diameters of said nudger roll and said feed roll with nominal diameters stored in a lookup table, and adjusting the nominal height of said elevator when the diameter of said nudger roll is less than a predetermined diameter and adjusting the roll speed of said feed roll when the diameter of said feed roll is less than a predetermined diameter in order to minimize sheet misfeeds and prevent tearing of copy sheets during transport through a paper path.