Image forming apparatus provided with self-diagnosis system

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.