초록 ▼

Disclosed are apparatus and method for detecting the presence, or absence, of material at a predetermined location. A crystal controlled oscillator generates a constant-frequency, constant-amplitude signal which is fed through a load resistor to an antenna sensor circuit, including an antenna probe

Disclosed are apparatus and method for detecting the presence, or absence, of material at a predetermined location. A crystal controlled oscillator generates a constant-frequency, constant-amplitude signal which is fed through a load resistor to an antenna sensor circuit, including an antenna probe positioned at the sensing location. The amplitude of the signal fed to the sensor circuit varies as the impedence of the antenna probe is affected by material in its environment, or the lack thereof. The signal amplitude is converted to a d-c voltage level, which is added to a reference d-c voltage level preset with the antenna probe free of impedance-affecting material. The difference voltage level value thus obtained, and which reflects the environment of the antenna probe, is used to control a switching circuit whose output assumes one value or another, depending ultimately on the antenna probe\s environment. The output from the switching circuit may be used to operate one or more devices indicating the environment of the antenna probe, and/or affecting the environment by adding to, and/or removing therefrom, material affecting the impedance of the antenna probe.

대표청구항 ▼

Apparatus for detecting the presence or absence of material at a location comprising: (a) signal generation means for providing an oscillatory signal; (b) sensor means, including antenna probe means for positioning at said location, and for receiving said oscillatory signal; (c) converter means for

Apparatus for detecting the presence or absence of material at a location comprising: (a) signal generation means for providing an oscillatory signal; (b) sensor means, including antenna probe means for positioning at said location, and for receiving said oscillatory signal; (c) converter means for producing a voltage level whose value is dependent on the amplitude of said oscillatory signal so received by said sensor means; (d) set point circuit means for producing a voltage reference level to which said voltage level produced by said converter means is added; and (e) switching means, operable by the voltage sum of said voltage reference level and said voltage level, for providing an output signal dependent on the presence or absence of material at said location.