US 4,879,461 A · Energy field sensor using summing means

Abstract

An energy field disturbance sensor comprises an energy field emission means such as a light emitting diode; the emitted field may contain a time-varying component. An energy sensing device such as a photodiode receives the field energy to produce a sensing signal related to the intensity of the emitted field and any disturbance therein. A second signal complementary to the sensed signal is added in a summing junction to the sensing signal to create a summation signal. If the emitted energy field contains a time-varying component, a detection circuit is used to sample the summation signal to convert the summation signal to a proportional detection signal. An analog to digital converter converts the detection signal to a digital form. Digital processing circuitry modulates the amplitude of the complementary signal or the intensity of the energy field according to the desired mode of operation, and in accordance with the behavior of the digital detection signal and external control signals. The circuitry is capable of creating a null condition in the detection signal when the received amplitude of the energy field is such that when added to the complementary signal a cancellation effect occurs; the null condition may be transient or continuous in nature depending on the mode of operation and the nature of the field disturbance.

Claims20

Dependent claims

An apparatus for sensing a disturbance within a sensing region, comprising:

an emitting means for emitting a field of energy, said field of energy being disturbed by a change in said sensing region;
sensing means for receiving energy from the emitted field of energy to produce a corresponding sensing signal;
signal generation means for producing an electrical signal complementary in nature to the sensing signal that includes a digital to analog converter means for digital control of the amplitude of the electrical signal complementary to the sensing signal;
summing means for adding the sensing signal and the electrical signal complementary to the sensing signal to create a summation signal whose amplitude is less than the sensing signal or opposite in polarity to the sensing signal;
and
detection means responsive to the summation signal to create a detection signal indicative of an energy field disturbance, such means including a conversion means to translate the detection signal to a digital signal proportionate to the level of the detection signal.

3 more elements

Dependencies are inferred from the claim text.

Energy field sensor using summing means

Life of this patent

Energy field sensor using summing means

Life of this patent

Abstract

Claims20