| 摘要 |
PURPOSE:To allow even a person having difficulty in hard of hearing or a deaf-mute to utilize effectively a telephone set by discriminating what a station signal is, representing the state of a trunk line sent from a line and displaying the result visually. CONSTITUTION:Signal tone detection sections 7, 8 consist of a phase locked loop circuit, are locked when a signal with a prescribed frequency comes and output a signal while being locked and the signal tone detection section 7 is set to 400Hz and the section 8 is set to 2100Hz respectively. Further, a control section 9 consists of a microprocessor etc. and the operation of a message sending section 6 is controlled by the section 9. On the other hand, a display section 11 consists of a display element such as a light emitting diode and is connected to the control section 9 via a drive section prescribed message is sent to the opposite party.
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