| 摘要 |
PROBLEM TO BE SOLVED: To reduce a power consumption of a device by making each part including a transmission circuit an active mode when connection of an ID card is detected and making each part including the transmission circuit an inactive mode when the connection of the ID card is not detected. SOLUTION: When an ID card 5 is inserted in a card I/F 42 of a button telephone set 3, a CPU 33 makes the button telephone set 3 an active mode and allows its use when an ID number of the ID card 5 coincides with an ID registered in a memory 38. When the use of the button telephone set 3 is completed and the ID card 5 is pulled out, the CPU 33 stops data transmission to a main device, clears display of an LCD display circuit 39 and each LED of an LED display circuit 40, stops operation of a tone ringer 41 and the CPU 33 itself enters a standby mode of a low power consumption mode. As long as the ID card 5 is not inserted in the button telephone set 3, each display goes out, transmission from a speaker SP of the tone is not performed either, and the power consumption of the button telephone set 3 is reduced.
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