US 4,105,902 A · Touch sensitive input for electronic wristwatch and/or electronic calculator

Abstract

A touch sensitive input particularly suited for use with an electronic wristwatch, an electronic calculator or a combination thereof is provided. The touch sensitive input includes a touch sensitive contact connected to the input of a detector circuit, the detector circuit input being normally referenced to a first potential for producing a detector circuit output signal representative of the first potential. Engagement of the touch sensitive contact selectively references the detector circuit input to a second potential and in response thereto produces a detector circuit output signal representative of the second potential. The detector circuit includes at least an MOS or C-MOS input stage. Additional circuitry is provided for eliminating chatter in the output signal produced by the input stage, for preventing the producing of two signals representative of the unintended engagement of more than one touch sensitive contact, and for providing an indication that a touch sensitive contact has been inadvertently engaged.

Claims11

Dependent claims

A touch sensitive input for an electronic utilization device comprising a voltage source referenced to a first potential, touch sensitive contact means, said touch sensitive contact means including a conductive resistive contact member for connection to ground through the skin resistance of a user upon engagement thereof by the user;

and detector circuit means including a C-MOS inverter input stage having an input to which said touch sensitive contact member is connected and an output, a resistor coupled intermediate said voltage source and said C-MOS inverter stage input, said resistor being selected to have a value substantially greater than the value of the average skin resistance of a likely user so that the input of said inverter stage of said detector circuit means is normally referenced to said first potential for producing a detector circuit output signal representative of said first potential, said touch sensitive contact means selectively referencing said detector circuit means input to a second potential in response to engagement of said touch sensitive contact member to ground through the skin resistance of a user, said detector circuit means producing at its output a detector circuit output signal representative of the second potential in response to application of said second potential to the input thereof.

A touch sensitive input for an electronic utilization device comprising at least two touch sensitive contact means;

and detector circuit means associated with each touch sensitive contact means having an input to which said touch sensitive contact means is connected and an output, each said detector circuit means including means normally referencing the input thereof to a first potential for producing a detector circuit output signal representative of said first potential, each of said touch sensitive contact means selectively referencing said detector circuit means input to a second potential in response to engagement of said touch sensitive contact means, said detector circuit means producing at its output a detector circuit output signal representative of the second potential in response to application of said potential to the input thereof, and multiple input prevention circuit means for receiving the outputs of said detector circuit means for selectively transmitting only the first of overlapping output signals of said detector circuit means representative of said second potential.

Dependencies are inferred from the claim text.

Touch sensitive input for electronic wristwatch and/or electronic calculator

Life of this patent

Touch sensitive input for electronic wristwatch and/or electronic calculator

Life of this patent

Abstract

Claims11