Apparatus having self-repairing function and method of self-repairing the same.

摘要

According to the present invention, a concept of functional quantities indicative of quantified functional degrees of such lower-level functions as "clearer characters", "cleaner background", and "thicker characters", which are subordinating to a qualification-oriented function of "more attractive characters". Characteristic patterns of functional quantities F1, F2 and F3 of the lower-level functions for physical parameters (for example, the surface potential of a photoreceptor body) are prepared. When a fault repair is implemented by changing a value of a physical parameter, a tradeoff is made between lower-level functions which are influenced by the physical parameter. That is, taking into account the functional quantities F1, F2 and F3 of the lower-level functions, the value of the physical parameter is set so that the functional quantity of the function of "more attractive characters" is maximized. By introducing the concept of the functional quantities indicative of the quantified functional degrees of the functions, a flexible self-repairing function can be realized, thereby optimizing a repair operation.