Solid state capacitive switch
First Claim
1. A momentary switch, comprising:
- a dielectric layer having an exposed surface;
an amplifier having an ungrounded input node and an ungrounded output node;
first and a second capacitor plates covered by a thin layer of said dielectric layer to place said exposed surface within an electric field-influence of said first and second capacitor plates, said first capacitor plate being connected to said input node and said second capacitor being connected to said output node;
wherein a magnitude of a signal at said output node is responsive to a proximity of an ungrounded object to said exposed surface;
and a signal comparator for comparing a signal at said output node of said amplifier to a reference voltage.
2 Assignments
0 Petitions
Accused Products
Abstract
A fingertip-operated solid state capacitance switch detects a capacity change that is induced by the physical contact of an ungrounded fingertip to an external dielectric surface of the solid state switch. The input and output of a solid state signal-inverting amplifier are respectively connected to two relatively large and ungrounded capacitor plates that are associated with, but electrically isolated from, the switch'"'"'s external dielectric surface. An ungrounded fingertip forms a third capacitor plate on the switch'"'"'s external surface. The solid state amplifier detects the presence of a fingertip on the switch'"'"'s external surface by way of a change in capacitance within a compound, three plate, capacitor that includes the two ungrounded capacitor plates and the ungrounded fingertip that is resident on the switch'"'"'s external surface. An automatic gain control circuit is provided to adjust the value of an amplifier reference voltage when the solid state switch is not operating, thereby allowing the solid state switch to adapt to changeable ambient conditions. A momentary switch and a toggle flip-flop latched switch are provided. A linear switch array having a movable control knob and a linear LED indicator array is provided. The momentary solid state switch is constructed to operate as a temporal code detector that detects a coded sequence of switch-taps and a coded time interval between adjacent switch-taps.
-
Citations
10 Claims
-
1. A momentary switch, comprising:
-
a dielectric layer having an exposed surface; an amplifier having an ungrounded input node and an ungrounded output node; first and a second capacitor plates covered by a thin layer of said dielectric layer to place said exposed surface within an electric field-influence of said first and second capacitor plates, said first capacitor plate being connected to said input node and said second capacitor being connected to said output node; wherein a magnitude of a signal at said output node is responsive to a proximity of an ungrounded object to said exposed surface; and a signal comparator for comparing a signal at said output node of said amplifier to a reference voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
Specification