Matsushita Electric Industrial Co., Ltd.

Kunito Miyamoto

Toshibumi Kamiyama

A frost detector comprises a piezoelectric element secured on a metal diaphragm and inside an air-tight space formed by the diaphragm, a base and a bellows which air-tightly and resiliently connects the diaphragm and the base, the base being secured on a fin of a heat exchanger, the piezoelectric element being connected to an oscillation circuit and an oscillation detection circuit; resonance frequency and impedance characteristic of the piezoelectric element being changed by frosting on the outside face of the diaphragm, and the frosting being detected through a change or stopping of the oscillation and resultant output signal by the oscillation detection circuit.

Frost detector

An input device for a tuner utilizing as an amplifier element a bipolar transistor or tetrode metal-oxide-semiconductor field-effect transistor is provided in which an impedance means is connected in parallel with an impedance of an antenna; a capacitor means is inserted between the input terminal of the amplifier element and a group of tuning coils or inductance means for selecting the television channels in the high frequency band when a channel in the high frequency band is selected whereas an inductance means is inserted between the input terminal and a group of tuning coils for selecting the channels in the low frequency band when a channel in the low frequency band is selected; and an impedance means is inserted between the input terminal of the amplifier element and the earth. The tuning frequency band widths or selectivities in both the high and low frequency bands may be made substantially equal without causing the loss due to the impedance mismatching even when the input impedance of the amplifier element varies greatly in response to the change in frequency.

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Kitano, Japan

Kunito Miyamoto