| 摘要 |
PURPOSE:To reduce the number of components, the cost of manufacture and a circuit scale and to ensure communication between indoor and outdoor control circuits by making an outdoor power circuit of an outdoor machine common and by dispensing with a photocoupler for electric insulation. CONSTITUTION:A DC voltage from a DC power circuit 11 of an outdoor machine 15 is transmitted to an indoor machine 14 through connection lines 17a and 17b and made a supply voltage of an indoor blower 6, an indoor control circuit 9 and others. In the indoor machine 14, a modulation-demodulation circuit 12-a is connected to the connection lines 17a and 17b by a transformer 20-a and an information signal from the indoor control circuit 9 is modulated, sent to the transformer 20-a, superposed on the DC voltage and sent to the outdoor machine 15 through the connection lines 17a and 17b. In the outdoor machine 15, the information signal is separated from the DC voltage by a transformer 20-b, demodulated by a modulation-demodulation circuit 12b and supplied to an outdoor control circuit 10. In the case when the information signal is transmitted from the outdoor control circuit 10 to the indoor control circuit 9, a channel reverse to the above is taken. |
