Image forming apparatus capable of making self-diagnosis

An image forming apparatus capable of making self-diagnosis of a fault developed by the image forming apparatus, comprising:

• outputting means for outputting, as a plurality of faults and a plurality of sets of qualitative values of parameters representing the state of each of the faults, the results obtained by qualitatively expressing said image forming apparatus by a casual relation network of parameters representing the property of the image forming apparatus and qualitatively simulating all states which can exist on the image forming apparatus using said casual relation network of parameters when it is assumed that a fault symptom appears on the image forming apparatus;
• a plurality of sensors for detecting the states of a predetermined plurality of portions in the image forming apparatus;
• landmark storing means having stored therein landmarks in a qualitative quantity space which are respectively defined using fuzzy membership functions and required for converting detected values of the sensors into qualitative values;
• converting means for reading the detected values of said respective sensors when the fault symptom actually appears on the image forming apparatus, to convert the detected values of the sensors into fuzzy qualitative values respectively using the membership functions stored in said landmark storing means;
• and
• fault specifying means for comparing a set of fuzzy qualitative values obtained by the conversion using said converting means with the plurality of sets of qualitative values of parameters representing the state of each of the faults which are outputted from said outputting means, to specify the fault represented by the set of qualitative values which is in a predetermined relationship to the set of fuzzy qualitative values as a fault causing the fault symptom actually appearing.

In a control device for converting detected values obtained from an image forming apparatus which is a controlled object into qualitative values to carry out predetermined control using the qualitative values obtained by the conversion, the control device is characterized by comprising:

• landmark storing means having stored therein landmarks in a qualitative quantity space which are respectively required in converting said detected values into the qualitative values;
• landmark correcting means for correcting the landmarks stored in said landmark storing means respectively using at least the detected values obtained when the image forming apparatus is forced to develop the fault at predetermined timing;
• and
• converting means for converting the detected values obtained from the image forming apparatus into the qualitative values respectively using the landmarks corrected.

An image forming apparatus capable of making self-diagnosis of a fault developed by the image forming apparatus, comprising:

• outputting means for outputting, when it is assumed that a fault symptom appears on the image forming apparatus, a plurality of faults causing the fault symptom and a plurality of sets of qualitative values of parameters representing the state of each of the faults;
• a plurality of sensors for detecting the states of a predetermined plurality of portions in the image forming apparatus;
• landmark storing means having stored therein landmarks in a qualitative quantity space which are respectively defined using fuzzy membership functions and required for converting detected values of the sensors into qualitative values;
• landmark correcting means for correcting the landmarks stored in said landmark storing means respectively using the detected values of said plurality of sensors read when the image forming apparatus is forced to develop the fault at predetermined timing;
• converting means for reading the detected values of said plurality of sensors when the fault symptom actually appears on the image forming apparatus, to convert the detected values of the sensors into the qualitative values respectively using the landmarks stored in said landmark storing means;
• and
• fault specifying means for comparing a set of qualitative values obtained by the conversion using said converting means with the plurality of sets of qualitative values corresponding to the plurality of faults which are outputted from said outputting means, to specify a fault causing the fault symptom actually appearing.

An image forming apparatus capable of making self-diagnosis of a fault developed by the image forming apparatus, comprising:

• virtual case storing means having stored therein, when it is assumed that a fault symptom appears on the image forming apparatus, a plurality of faults causing the fault symptom and a plurality of sets of qualitative values of parameters representing the state of each of the faults;
• a plurality of sensors for detecting the states of a predetermined plurality of portions in the image forming apparatus;
• landmark storing means having stored therein landmarks in a qualitative quantity space which are respectively defined using fuzzy membership functions and required for converting detected values of the sensors into qualitative values;
• landmark correcting means for correcting the landmarks stored in said landmark storing means respectively using the detected values of said plurality of sensors read when the image forming apparatus is forced to develop the fault at predetermined timing;
• converting means for reading the detected values of said plurality of sensors when the fault symptom actually appears on the image forming apparatus, to convert the detected values of the sensors into the qualitative values respectively using the landmarks stored in said landmark storing means;
• and
• fault specifying means for comparing a set of qualitative values obtained by the conversion using said converting means with the plurality of sets of qualitative values which are stored in said virtual case storing means, to specify a fault causing the fault symptom actually appearing.