Patent ID: 7330551

Claim:
An apparatus for controlling an input signal level recognized when an input signal is inputted to a device, said apparatus comprising: a memory storing values including a current input signal level to be controlled, a previous input signal level which is a level of an input signal preceding a current input signal, a maximum change value which is an upper limit of an allowable range of level variation in the device, a maximum no-change value which is an upper limit of an allowable range of level invariation in the device, a change counter value which is a number of input signals having different levels detected by comparing the current input signal level with the previous input signal level, and a no-change counter value which is a number of input signals having a same level detected by comparing the current input signal level with the previous input signal level; a determining unit determining whether corresponding values stored in said memory are substantially identical, based either on the maximum change value and the change counter value, or on the maximum no-change value and the no-change counter value, and outputting a determination; and a control unit reading the values stored in said memory to output the values to said determining unit and storing a predetermined level as the current input signal level based on the determination by said determining unit as to whether said corresponding values are substantially identical.