Abstract: An indoor unit included in an air conditioner that includes an outdoor unit includes a power receiving circuit (PR2), a low-frequency transmission and reception circuit as a first reception circuit, a high-frequency transmission and reception circuit as a transmission and reception circuit, and an inner-controller. The low-frequency transmission and reception circuit receives a current signal transmitted from an outdoor unit by using a current loop formed by a power line included in power supply wiring. For a first communication state in which physical connection between with the outdoor unit is recognized and a second communication state in which communication for operation of the air conditioner is performed between with the outdoor unit, the inner-controller selects use of the low-frequency transmission and reception circuit and the high-frequency transmission and reception circuit in the first communication state and the second communication state.

Abstract: A method is provided for fabricating thin film amorphous silicon p-i-n photodiode array image sensors that have transparent photodiode electrodes made of indium tin oxide or SnO.sub.2 and thin-film aluminum conductors for connecting the transparent electrodes to signal processing circuitry. The method provides for patterning of the aluminum conductors without eroding the material of the transparent electrodes through reduction of such material by hydrogen gas released during etching of the aluminum by using a photoresist etch mask that covers the areas of the transparent electrodes and defines the pattern of the aluminum conductors.