Mita Industrial Co., Ltd.

Yasuo Motegi

Hiroyuki Yoshikawa

Tetsuo Tomiyama

Yasushi Umeda

Yoshiki Shimomura

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.

Image forming apparatus provided with self-diagnosis system

The amount of degradation, converted into a fuzzy qualitative value, is found on the basis of state data sensed by sensors 1a, 1b and 1c and degradation data. The value of a parameter changed by the amount of degradation is represented by a fuzzy qualitative value. In addition, the state data is converted into a fuzzy qualitative value, and it is judged by the value whether or not a fault exists. As a result, if a fault exists, fault diagnosis is made utilizing, as an initial value the value, of the parameter changed by the amount of degradation, and the causes of the fault are specified by comparing the result of the diagnosis with the state data converted into the fuzzy qualitative value. The causes of the fault specified are repaired by operating corresponding actuators 6a, 6b and 6c. Since the causes of the fault are specified while handling the fuzzy qualitative value, the causes of the fault can be specified more precisely. Accordingly, it is possible to achieve an image forming apparatus in which autonomy is high and repair labor is reduced.

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Gunma, Japan

Yasuo Motegi