Patent ID: 7269372

Claim:
A method of determining a condition of an oxidation catalyst filter of an oxidation catalyst unit that is coupled to a fixing unit of a wet-type electrophotographic image forming apparatus to purify carrier vapor generated in the fixing unit through an oxidation catalyst reaction, the method comprising: sensing a temperature T in of atmosphere flowing into the oxidation catalyst filter; sensing a temperature T out of atmosphere flowing out of the oxidation catalyst filter; comparing data on the temperatures T in and T out to calculate a difference ΔT between the temperatures T in and T out ; comparing the difference ΔT with input reference data to determine a condition of the oxidation catalyst filter; calculating an average density P a of ink fixed on an output printing medium of the wet-type electrophotographic image forming apparatus, wherein the input reference data comprises an allowed basic temperature difference ΔT b corresponding to the average density P a of the ink; and displaying an error state when the difference ΔT is less than the allowed basic temperature difference ΔT b .