| 摘要 |
<p>PROBLEM TO BE SOLVED: To detect the presence of a human body by supplying an alternating current signal from an LC oscillation circuit to a pair of electrode bodies formed at one face of an insulating substrate and detecting an oscillation frequency of the signal. SOLUTION: A sensor plate 1 has an insulating flexible thin substrate 11. A pair of electrode bodies 12, 13 are arranged side by side via a predetermined distance on one face of the substrate. When a high frequency alternating current signal is impressed from an oscillator 2 consisting of an LC oscillation circuit to the electrode bodies 12, 13, the electrode bodies 12, 13 radiate minute electromagnetic waves. An oscillation frequency at this time is determined by a C component and an L component present in the neighborhood. When a person is on a bed, the oscillation frequency is changed due to the application of a capacitance of the person, which is connected to a frequency detection circuit 3 and measured. A controller 4 recognizes the presence of the person from the change. Accordingly, the presence/absence of the person on the bed can be surely detected in a noncontact manner.</p> |
