| 摘要 |
PURPOSE:To maintain an even speech level which is inputted from a microphone no matter how remote a speaker and the microphone are located for thereby accomplishing an invariably stable speech recognition, by providing the front surface of heating device with a distance detecting sensor adapted to detect a distance between the speaker and the microphone and a gain control means adapted to control the magnitude of amplification of speech input section responsive to an output signal from a distance detection means consisting of the sensor and an amplifier. CONSTITUTION:A gain control means 26 functions to rectify and smooth an output signal from a distance detecting means 24 for a diode D, a resistor R1 and a condenser C. The signal thus smoothed drives the LED of photocoupler 27 for varying the resistance layer of CDS. The CDS is connected with the resistor R of AMP 2 of speech input means 20 in parallel, and has its resistance value increased for thereby causing a speech input section 20 to increase its magnitude of amplification when, as for instance, a focusing type infra-red ray sensor is used, because a smoothed signal is of small magnitude and the flow of electric current to the LED is marginal. On the contrary, when the distance is short, the smoothed signal is of large magnitude and a greater amount of electric current flows to the LED for reducing the resistance value of CDS, thereby bringing down the magnitude of amplification for the speech input section 20. |
