| 摘要 |
PURPOSE:To attain switching with natural operation, by using a nonlock type switch of two make-contacts of simple mechanism, and changing over the state from a handset call to the loudspeaker reception or vice versa. CONSTITUTION:The nonlock type switch having two make-contacts 33, 33' is used as a loudspeaker reception switch LS. In depressing the LS and the contact 33 is closed, a station power supply voltage is applied to a power supply circuit 8 via a power separation circuit 6, an output voltage V of the circuit 8 activates a switch control circuit 31, and an electronic hook switch 32 is set on before the contact 33 is opened with an output (k) of the circuit 31, a subscriber line loop is held and the station power supply voltage is kept to be supplied to the circuit 8. Thus, the circuit 31 controls the switching of the switch so that the operating state is changed over among four states; waiting, handset call, on- hook loudspeaker and off-hook loudspeaker. |
