OPERATION PANEL INPUT DEVICE

摘要

PROBLEM TO BE SOLVED: To provide an operation panel input device which enlarges and detects only an increment of light reception by an input operation and can precisely judge the input operation. SOLUTION: An amplification means (18) amplifying a photoelectric conversion signal outputted from a light reception means (6a) is constituted of a differential amplification circuit (18) inputting the photoelectric conversion signal and an offset signal and outputting an amplification signal amplified at a fixed amplification rate (A). An input judgement means (10) outputs the offset signal so that a value of the amplification signal inputted from the differential amplification circuit (18) at every detection period becomes a set value in a next scanning period (T) and operates light reception quantity from values of the inputted amplification signal and the offset signal inputted when the amplification signal is outputted. The amplification signal changes with the set value as a center. Change quantity amplifies a level change of the photoelectric conversion signal at the amplification rate (A). Consequently, it can securely be detected even if the change by the input operation is small. COPYRIGHT: (C)2004,JPO