Image forming apparatus provided with self-diagnosis system

• US 5,467,355 A
• Filed: 09/01/1994
• Issued: 11/14/1995
• Est. Priority Date: 04/13/1992
• Status: Expired due to Term

• Current Assignee: Mita Industrial Co., Ltd. (Kyocera Corporation)
• Original Assignee: Mita Industrial Co., Ltd. (Kyocera Corporation)
• Inventors: Yoshikawa, Hiroyuki, Shimomura, Yoshiki, Motegi, Yasuo, Tomiyama, Tetsuo, Umeda, Yasushi
• Primary Examiner(s): Beausoliel, Jr., Robert W.
• Assistant Examiner(s): LE, DIEU MINH T
• Application Number:
  US08/299,082
• Time in Patent Office: 439 Days
• Field of Search: 371/29.1, 371/15.1, 371/16.4, 371/7, 371/47.1, 371/16.2, 371/17, 371/9.1, 371/38.1, 395/50, 395/54, 395/575, 395/916, 364/276.3, 364/281.9, 364/285, 364/221.2, 364/268.9
• US Class Current: 702/184
• CPC Class Codes: G03G 15/55 Self-diagnostics; Malfunction or lifetime display
• CPC Class Codes: G03G 2215/00118 using fuzzy logic
• CPC Class Codes: G06F 11/2257 using expert systems
• CPC Class Codes: Y10S 706/90 Fuzzy logic
• CPC Class Codes: Y10S 706/911 Nonmedical diagnostics

Abstract

In an image forming machine, an objective model storage device stores parameter data that represent elements of the machine and relationships among such parameters, and parameter membership functions, and fault diagnosis knowledge. A degradation storage device stores a fuzzy qualitative value for a parameter changed by degradation of an element of the machine. Preferably, degradation indicative data are converted into fuzzy qualitative values, and the value of the parameter changed by degradation is represented by a fuzzy qualitative value. The machine includes sensors for sensing functional states thereof, and providing state data representative of such states. The state data sensed by the sensors are converted into fuzzy qualitative values. Then, a fault judgement device determines whether or not a fault exists by comparing the obtained fuzzy qualitative values with the parameter data stored in the objective model storage device. If the fault judgement device determines that a fault exists, a fault diagnosis device performs fault diagnosis by utilizing, as an initial value, the value of the parameter changed by degradation. A specification device specifies fault causes by comparing the result of the diagnosis with the state data which was converted into the fuzzy qualitative values. Then, a repair device operates actuators of the machine to overcome the specified fault.

Claims

1. An image forming apparatus provided with a self-diagnosis system, comprising:

objective model storage means for storing data that represent the image forming apparatus as a combination of a plurality of elements, qualitative parameter data that represent, as parameters, attributes of respective elements of the plurality of elements and a combinational relationship between the elements, parameter membership functions corresponding to the parameters, and fault diagnosis knowledge;

degradation data storage means for storing degradation data representing an amount of degradation undergone by at least one component of the image forming apparatus after use of the image forming apparatus has started;

a plurality of sensor means for sensing a functional state of a predetermined portion of the image forming apparatus and outputting state data indicative thereof;

degradation amount calculation means for calculating the degradation of the at least one component from after the image forming apparatus starts to be used to the present time on the basis of degradation data stored in the degradation data storage means;

change calculation means for representing as a fuzzy qualitative value, the value of a changed parameter which has been changed by an amount of degradation calculated by the degradation amount calculation means from among qualitative parameter data stored in the objective model storage means by using the membership function corresponding to the changed parameter;

data conversion means for converting state data outputted by the sensor means into a fuzzy qualitative value by applying parameter membership functions stored in the objective model storage means;

fault judgement means of judging whether or not a fault exists by comparing a fuzzy qualitative value from the data conversion means with qualitative parameter data stored in the objective model storage means; and

fault diagnosis means for diagnosing the functional state of the image forming apparatus on the basis of qualitative parameter data and fault diagnosis knowledge stored in the objective model storage means by utilizing as initial conditions a fuzzy qualitative value from the change calculation means in response to a judgement that a fault exists by the fault judgement means, and for outputting a result of the diagnosis as an expression which has ambiguity and which indicates the state of the image forming apparatus.

2. An image forming apparatus according to claim 1, further comprising:

a plurality of actuator means for changing functional states of the image forming apparatus;

cause specification means for specifying fault causes by comparing a fuzzy qualitative value obtained by the data conversion means with the state of the image forming apparatus as outputted by the fault diagnosis means; and

repair means for selectively operating the plurality of actuator means so as to remove fault causes specified by the cause specification means.

3. An image forming apparatus according to claim 2, wherein the repair means includes judgement means for judging whether a fault cause specified by the cause specification means is repairable or not repairable;

and means for effecting repair only when the judgement means judges that the fault cause is repairable.

4. An image forming apparatus according to claim 1, wherein the objective model storage means further stores a reference value indicative of occurrence of a fault, and the change calculation means calculates a degree of occurrence of a fault in the image forming apparatus based on degradation calculated by the degradation amount calculation means.

5. An image forming apparatus according to claim 4, wherein the cause specification means specifies a fault cause according to the degree of occurrence of a fault as calculated by the change calculation means.

6. An image forming apparatus according to claim 5, wherein the repair means includes judgement means for judging whether a fault cause specified by the cause specification means is repairable or not repairable;

and means for effecting repair only when the judgement means judges that the fault cause is repairable.

7. An image forming apparatus provided with a self-diagnosis system, comprising:

objective model storage means for storing data that represent said image forming apparatus as a combination of a plurality of elements, qualitative parameter data that represent, as parameters, attributes of respective elements of the plurality of elements and a combinational relationship between the elements, parameter membership functions corresponding to each of the parameters, and fault diagnosis knowledge;

degradation data storage means for storing a fuzzy qualitative value for a changed parameter changed by degradation estimated for a predetermined fault diagnosis, the changed parameter corresponding to a predetermined one of a plurality of components constituting said image forming apparatus;

a plurality of sensor means for sensing a functional state of a predetermined portion of said image forming apparatus and outputting state data indicative thereof;

data conversion means for converting state data outputted by the sensor means into a fuzzy qualitative value by applying parameter membership functions stored in the objective model storage means during the predetermined fault diagnosis;

fault judgment means for judging whether or not a fault exists by comparing a fuzzy qualitative value from the data conversion means with qualitative data stored in the objective model storage means; and

fault diagnosis means for reading out, during fault diagnosis, a fuzzy qualitative value for a parameter from the objective model storage means and diagnosing the functional state of the image forming apparatus on the basis of qualitative data and fault diagnosis knowledge stored in the objective model storage means by utilizing the read out fuzzy qualitative value as an initial condition in response to a judgement that a fault exists by the fault judgement means, and for outputting a fault diagnosis result as an expression having ambiguity.

8. An image forming apparatus according to claim 7, further comprising:

a plurality of actuator means capable of changing functional states of said image forming apparatus;

cause specification means for specifying fault causes by comparing a fuzzy qualitative value obtained by the data conversion means with a state of said image forming apparatus as outputted by the fault diagnosis means; and

repair means for selectively operating the plurality of actuator means so as to remove fault causes specified by the cause specification means.

9. An image forming apparatus provided with a self-diagnosis and self-repair system, comprising:

objective model storage means for storing data that represent the image forming apparatus as a combination of a plurality of elements, qualitative parameter data that represent, as parameters, attributes of respective elements of the plurality of elements and a combinational relationship between the elements, parameter membership functions corresponding to each of the parameters, and fault diagnosis knowledge;

degradation data storage means for storing a fuzzy qualitative value for a changed parameter changed by an estimated amount of degradation for a predetermined fault diagnosis and a degree to which a fault phenomenon occurs in the image forming apparatus by the estimated amount of degradation, corresponding to a predetermined one of a plurality of components constituting said image forming apparatus;

a plurality of sensor means for sensing a functional state of a predetermined portion of said image forming apparatus and outputting state data indicative thereof;

a plurality of actuator means capable of changing functional states of said image forming apparatus;

data conversion means for converting state data outputted by the sensor means into a fuzzy qualitative value by applying parameter membership functions stored in the objective model storage means during the predetermined fault diagnosis;

fault judgment means for judging whether or not a fault exists by comparing a fuzzy qualitative value from the data conversion means with qualitative data stored in the objective model storage means;

fault diagnosis means for reading out, during a fault diagnosis, a fuzzy qualitative value for a parameter from the objective model storage means and diagnosing the state of said image forming apparatus on the basis of qualitative data and fault diagnosis knowledge stored in the objective model storage means by utilizing the read out fuzzy qualitative value as an initial condition in response to a judgement that a fault exists by the fault judgment means, and for outputting a fault diagnosis result as an expression having ambiguity;

cause specification means for specifying fault causes by comparing a fuzzy qualitative value obtained by the data conversion means with the state of said image forming apparatus as outputted by the fault diagnosis means; and

repair means for selectively operating the plurality of actuator means so as to remove fault causes specified by the cause specification means.