摘要 |
A charge level sensor in which the distance between the sensor and a sample to be sensed is maintained constant and the sensor is entirely protected from strain or contamination by foreign matter and is reduced in size. A rotary drum of aluminum is provided with plural recesses therein in which are disposed charge sensors, preferably MOS FET's. Holes are formed though the substrate leading into the recesses through which pass lead wires coupled to the sensors. The surface of the substrate, including the sensors, is covered by an electric-charge retaining layer such as a photosensitive material or a dielectric material.
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