| 摘要 |
PROBLEM TO BE SOLVED: To avoid the influence of a fluorescent lamp just near a receiver by connecting a serial resonator composed of an inductor and a capacitor to the inverted input terminal of an operation amplifier on the first step of the infrared receiver and selectively amplifying the required frequency band. SOLUTION: At a receiver 20 for infrared remote control signals, an infrared signal is photoelectrically converted by a PIN photodiode 21 and amplified by a first step operational amplifier 23. An automatic bias controller 22 is provided for preventing saturation on the first step or optimizing a DC operating point and when the first step enters a saturation area, the operating point is stabilized by impressing a bias current for canceling an optical current to the PIN diode 21. A limiter 24 is provided on the next step so as to suppress the sensitivity reduction to a minimum by preventing operation from being disabled even in the case of excessive light input. Since operating conditions can not be satisfied without lowering sensitivity in the case of interference light input, a resonator 26 is provided, the first step operational amplifier 23 selectively amplifies the frequency and the influence of an inverter type fluorescent lamp is reduced. After this signal amplification, the signal is filtered by a band pass filter + trap 25 and outputted. |
