# US 6,829,565 B2 · Stepper motor automated self-test routine

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- Number: US 6,829,565 B2
- Document ID: US6829565B2
- Status: Granted
- Kind: B2
- Application number: 10/369,043
- Filed: 2003-02-14
- Published: 2004-08-19
- Granted: 2004-12-07
- Earliest claimed: 2003-02-14
- Assignees: Xerox Corporation
- Inventors: Robert P. Siegel; Kevin E. Price
- Web page: https://patentgrep.com/patent/US6829565B2

## CPC

- G05B 19/406: characterised by monitoring or safety (G05B19/19 takes precedence)
- G05B 2219/37209: Estimate life of gear, drive
- G05B 2219/41326: Step motor
- G05B 2219/42303: Detect no speeding up of motor
- G05B 2219/45187: Printer
- G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G)

## Abstract

A printing apparatus includes a stepper motor automated self-test routine that gives an approximation of the state of the degradation of the stepper motor and/or its driven load. The test includes artificially increasing the starting frequency above normal and/or reducing the operation current below normal by a known and controllable amount to the stepper motor and tracking the level at which the motor is just able to start operating. By examining the magnitude and/or change in these levels, the remaining life and reliability of the motor can be predicted. Alternatively, the self-test routine could be used in conjunction with paper path sensors to determine the start time for a stepper motor. The start times are stored for trend analysis.

## Claims

### Claim 1

A method for diagnosing degradation of stepper motors due to wear, comprising the steps of:
a) identifying a stepper motor to be tested;
b) applying a predetermined frequency to the stepper motor that is greater than the nominal starting frequency for the stepper motor;
c) observing if the stepper motor starts;
d) recording the frequency if the motor starts as the start frequency;
e) decreasing the frequency to the stepper motor in predetermined increments if the motor does not start in step c);
f) observing if the stepper motor starts after each decreasing frequency; and
g) correlating the responses to the aging life of the stepper motor.

### Claim 2 (depends on 1)

The method of claim 1, including performing steps a)-g) in an image forming system.

### Claim 3 (depends on 1)

The method of claim 1, including the step of decreasing said frequency in step e) in increments of 100 Hz.

### Claim 4

A method for diagnosing whether a stepper motor is functioning properly, comprising the steps of:
a) identifying a stepper motor to be tested;
b) providing a paper sensor downstream of said stepper motor;
c) feeding a sheet from a tray;
d) stopping the sheet in a predetermined location upstream of said paper sensor within a nip that is driven by said stepper motor;
e) applying a predetermined current to said stepper motor that is less than its standard operating current;
f) starting a timer;
g) monitoring said paper sensor to determine state change indicating arrival of the sheet at said sensor within a predetermined time;
h) recording motor start time; and
i) storing said motor start current for trend analysis.

### Claim 5 (depends on 4)

The method of claim 4, including the step of increasing the current to said stepper motor by a predetermined amount when the sheet does not arrive at said sensor within said predetermined time.

### Claim 6 (depends on 4)

The method of claim 4, including performing steps a)-i) in an image forming system.