Capacitive transistorized signaling device

• US 4,088,904 A
• Filed: 05/10/1976
• Issued: 05/09/1978
• Est. Priority Date: 09/27/1973
• Status: Expired due to Term

• Current Assignee: Robert E Green
• Original Assignee: Robert E Green
• Inventors: Green, Robert E.
• Primary Examiner(s): Miller, Jr., Stanley D.
• Assistant Examiner(s): Davis, B. P.
• Application Number:
  US05/684,672
• Time in Patent Office: 729 Days
• Field of Search: 340/265 R, 328/119, 328/1-5, 307/308, 307/253
• US Class Current: 307/116
• CPC Class Codes: G01F 23/263 by measuring variations in capacitance of capacitors
• CPC Class Codes: G01K 7/34 using capacitative elements capacitors per se H01G
• CPC Class Codes: G01L 1/144 with associated circuitry G01L1/146 and G01L1/148 take precedence
• CPC Class Codes: G01L 9/0005 using variations in capacitance G01L9/0072 takes precedence
• CPC Class Codes: G01L 9/12 by making use of variations in capacitance , i.e. electric circuits therefor
• CPC Class Codes: H03F 3/45071 with semiconductor devices only
• CPC Class Codes: H03K 17/955 using a capacitive detector
• CPC Class Codes: H03K 17/962 Capacitive touch switches
• CPC Class Codes: H03K 17/975 using a capacitive movable element
• CPC Class Codes: H03K 17/98 having a plurality of control members, e.g. keyboard

Abstract

A capacitive transducer providing an output for a signal with respect to an on-off mode which depends on a signal having a step function, the signal source is fed to a transistor or suitable amplifier having its base connected to a capacitance sensing means. Resistors are provided for appropriate biasing, current limiting and drain functions as well as capacitors for capacitance balancing purposes. The capacitance sensing means can comprise a touch switch which when touched has its capacitance increased causing the device to function. The change in capacitance can be registered with respect to the rise time or the fall time of the signal, or the leading or trailing edge of the wave. The transistor or amplifier is connected to a load so that when a change of capacitance is sensed, the change will be registered. Other embodiments can incorporate differential amplification means and means to drive the active components with the voltage of the signal source or the clock voltage. The transducer element maybe incorporated into mechanical moving elements that provide an electrical analog of such movement.

Claims

1. A switch comprising:

a capacitive registering element having a conductive surface for purposes of acting as a capacitive element in conjunction with a second body placed in proximity thereto;

a means connected to said conductive surface for generating a signal having a sufficiently fast rise or fall time to cause the switch to function as a slope differentiation detector with respect to the fast rise or fall time in response to the second body placed in proximity to said capacitive registering element; and

,

an amplifier connected to said conductive surface and said signal means having an electrical load connected thereto.

2. The switch as claimed in claim 1 wherein:

the amplifier is a transistor.

3. The switch as claimed in claim 2 further comprising:

a capacitor connected across the base and emitter of said transistor.

4. The switch as claimed in claim 2 further comprising:

a resistor placed across the base and emitter of said transistor.

5. The switch as claimed in claim 1 wherein:

said amplifier is a differential amplifier.

6. The switch as claimed in claim 1 wherein:

said means for generating a signal provides the power to said amplifier.

7. The switch as claimed in claim 1 further comprising:

the combination device of at least a second switch having the elements of the switch in claim 1 wherein said means for generating a signal having a fast rise or fall time is in singular form and utilized for both switches by being connected in parallel thereto.

8. The combination device as claimed in claim 7 wherein:

said switches are connected to a keyboard formed with the capacitive coupling elements therein as its keys.