To prevent malfunction of an infrared switch when the amount of infrared light received by an infrared light receiving element changes.
A processing part 93 determines whether the change in the amount of infrared light received is sharp or not from data of the amount of infrared light received obtained by PD103 through a PD output input part 91. If the change is rapid, the processing part determines the change is caused by external light, and of the change is not rapid, the processing part conducts a series of processing operation caused by pressing the infrared switch. The same procedure can be conducted by referring the amount of integration of an output signal during a period when the change in the output signal from PD103 starts until the change thereof stops instead of using a rate of change in the output signal from PD103 per unit of time when the signal becomes a certain voltage level which is higher than the standard voltage level.
HASHII SHINJI
NAKANO KIYOTAKA
KAWAMURA MASAYUKI
OE TOSHIHARU
KOBAYASHI MAKOTO
TOTO YUPRO LTD