A capacitance transducer of human body medium for bed use

Abstract

The invention provides a human body medium capacity transducer used in bed. The invention comprises two sheets of copper electrodes which tiles on a bed and are connected with a control circuit by a conducting line. The control circuit comprises an LC oscillator, a frequency-voltage transformer, a voltage comparator and a relay; wherein, the copper electrodes are connected with the LC oscillator, and the outputting of the oscillator is connected into the frequency-voltage transformer, the outputting of which is connected with the voltage comparator, the outputting of which controls the relay. The invention is convenient to use and install, and the exterior is an ordinary blanket which can be used when tiled on the bed. The capacitance variation of the transducer is obvious, thereby being very sensitive and reliable. The invention is just two copper sheets; therefore, the material is simple and the cost is low. The capacity of the transducer changes according the changing of the contacting area and medium without needing power source. The invention is easier than the traditional pressure switch type transducer in installation, more effective than human body pyroelectric sensor and more reliable than an opto-electrical reflect-typed or shot-typed transducer.

Description

(1) Technical field [0001] The invention relates to a basic electrical component, specifically a capacitor. (2) Background technology [0002] Traditional human body media proximity sensors mainly include the following types: (1) Pressure switch. That is, a spring pressure switch is installed under the four feet of the hospital bed. After the patient goes to bed, the switch is triggered by pressure. This method is simple in principle, but it is inconvenient to install and easy to damage. (2) Human body pyroelectric sensor. Use the far-infrared rays radiated by the human body to sense the existence of the human body, but when the human body is still, the sensor has no output signal, so it is not suitable for hospital bed applications, but only suitable for detecting active radiation sources. (3) Photoelectric reflective or through-beam sensors. This method uses the principle of reflection or reflection of light, but the disadvantage is that it has low reliability and is e...

AI Technical Summary

Problems solved by technology

This method uses the principle of reflection or reflection of light, and the disadvantage is that it has low reliability and is easy to misuse.

(4) The traditional human body proximity capacitive sensor uses the human body as one pole of the capacitor and requires the human body to stand, which is not suitable for use in hospital beds

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