| 摘要 |
PURPOSE:To effect sure frost detection without effecting malfunction by a method wherein a reflection type light sensor is provided so as to oppose to the fin of the outdoor heat exchanger to detect the frosting of the fin. CONSTITUTION:The outdoor heat exchanger 1 is provided with a multitude of fins 1b fixed around pipes 1a flowing refrigerant. The reflection type light sensor 2 is provided so as to oppose to the fins 1b. When the fins 1b are not frosted, the light of emission unit 2a of the light sensor 2 almost passes through clearances between fins 1b, 1b, therefore, reflecting light does not exist substantially and the output voltage of the sensor 2 becomes zero or very weak. On the contrary, when the fins 1b are frosted, the light of the emission unit 2a is reflected by the frost F, therefore, the reflected light is received by a light receiving unit 2b and a high voltage is outputted. This output voltage is amplified by the amplifier 4 of a control unit 3 and, further, is compared with a set voltage by a comparator 5.
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