Temperature measurement apparatus and protection apparatus for sound signal converting device

摘要

An audio signal output from a tone generator is fed into a coil provided in a transducer for vibrating a sound board, so that a sound signal is generated by the vibration of the sound board. A predetermined DC voltage supplied by a constant voltage source circuit is superimposed on the audio signal by an adding circuit, so that the superimposed signal is fed into the coil. A current passing through the coil is sensed by a current sensing resistor, so that only a DC voltage component of a voltage signal on the both ends of the resistor is extracted by a low-pass filter circuit to be supplied to a microcomputer via an A/D converting circuit. The microcomputer figures out a resistance value and a temperature of the coil by use of the DC voltage component and the certain DC voltage value.

主权项

1. A protection apparatus for a sound signal converting device, the protection apparatus comprising:
a temperature measurement apparatus for a sound signal converting device having a coil and converting an electric signal to a sound signal by energizing the coil, the temperature measurement apparatus measuring temperature of the coil and comprising:
a constant voltage source circuit connected to an input side of the coil to apply a DC voltage having a predetermined voltage value to the coil;a current value extracting circuit connected to the coil to extract a signal indicative of a value of direct current passing through the coil; anda processor configured to receive the signal extracted by the current value extracting circuit, and determine the temperature of the coil based on the direct current value and the predetermined voltage value; and a protection circuit configured to interrupt energization of the coil for transmission of an electric signal or decrease an amount of energization of the coil for transmission of the electric signal when the temperature of the coil determined by the processor becomes equal to or greater than a predetermined temperature.