PUSHBUTTON KEYBOARD SWITCH ARRAY AND ASSOCIATED PRINTED CIRCUIT LOGIC CARDS

• US 3,676,615 A
• Filed: 07/13/1970
• Issued: 07/11/1972
• Est. Priority Date: 07/13/1970
• Status: Expired due to Term

• Current Assignee: Fritz S. Wiedmer
• Original Assignee: Fritz S. Wiedmer
• Inventors: Wiedmer, Fritz S.
• Primary Examiner(s): Scott, J. R.
• Application Number:
  US05/054,300
• Time in Patent Office: 729 Days
• Field of Search: 200/1R,5R,5E,16A,83R,86R,159B 317/11CE
• US Class Current: 200/1.00R
• CPC Class Codes: H01H 13/702 with contacts carried by or formed from layers in a multilayer structure, e.g. membrane switches
• CPC Class Codes: H01H 2207/012 via underside of substrate
• CPC Class Codes: H01H 2207/014 Plated through holes
• CPC Class Codes: H01H 2207/016 Jumpers; Cross-overs
• CPC Class Codes: H01H 2217/016 Pressure reduction membrane; Spreader layer
• CPC Class Codes: H01H 2221/00 Actuators
• CPC Class Codes: H01H 2221/024 Transmission element
• CPC Class Codes: H01H 2221/05 Force concentrator; Actuating dimple
• CPC Class Codes: H01H 2221/058 to avoid tilting or skewing of contact area or actuator
• CPC Class Codes: H01H 2221/064 Limitation of actuating pressure
• CPC Class Codes: H01H 2223/002 sealed
• CPC Class Codes: H01H 2229/032 Screw
• CPC Class Codes: H01H 2239/026 Internal encoding, e.g. validity bit
• CPC Class Codes: H03M 11/22 Static coding H03M11/26 takes precedence

Abstract

In a keyboard, an elastic diaphragm switch array and logic, including strobe and rollover protection. The switch includes a diaphragm, a separator, and a switch card. The diaphragm comprises a gold plated continuous sheet of thin spring material and serves as a ground or voltage plane. The switch card has a gold plated pie pattern or switch array at each key location, with generally as many pie sections as there are bits in the code to be produced. Each pie section is wired directly by double sided wiring and through-holes in the switch card to the appropriate output code pin. No decoding or encoding logic is required to produce the code. Strobe logic is provided for assuring that all pie sections have made contact with the diaphragm and rollover protection logic is provided for assuring that only one key is depressed. A key button is provided for pressing the diaphragm through the separator to make contact with the switch card pie pattern.

Claims

1. A keyboard apparatus, comprising:

at least one switch actuator, an elastic diaphragm, and a switch card;

said switch card comprising a substrate having a plurality of arrays of switching elements and a plurality of groups of output pins, each said element of a given array being electrically connected by double-sided wiring on said substrate to an output pin in a separate group;

separator means disposed between said elastic diaphragm and said switch card for separating said diaphragm from said switching elements when said actuator is inoperative, said elastic diaphragm comprising a thin continuous sheet of conductive spring material;

each said switch actuator being actuatable to deflect said diaphragm through said separator into electrical contact with its associated array of said switching elements, whereby an output code is generated at said pins directly from said elements with an output signal present at at least one output pin of each group.

2. The keyboard means of claim 1 further comprising rollover protection logic means responsive to the output code at said pins for detecting simultaneous electrical contact between said diaphragm and a plurality of switching elements of different arrays.

3. The keyboard of claim 1 further comprising strobe logic means responsive to the output code at said pins for detecting electrical contact between said diaphragm and all of the switching elements of an array.

4. In an elastic diaphragm keyboard apparatus, a switch actuator means for moving the elastic diaphragm means into contact with a selected array of switching elements, comprising:

annular stop surface means for controlling the distance of travel of said switch actuator means, and actuator means integrally coupled to said surface means and disposed along the axis thereof, for causing deflection of said diaphragm, said diaphragm means being deflected upon actuation of said switch actuator means a distance equal to the protrusion of said actuator means through said stop surface means.

5. The keyboard apparatus of claim 4 further comprising distributor means disposed between said switch actuator means and said diaphragm means for transmitting the actuation force from said switch actuator means to said diaphragm means.

6. A keyboard comprising:

switch card means, having a plurality of arrays of three or more switching element means and conductive land pattern and throughhole means connecting said switching elements to a plurality of groups of output connector means, with each switching element means of each array connected to an output connector means of one of said groups, for producing an output code, elastic diaphragm means comprising a thin continuous sheet of conductive spring material for providing a voltage source, separator means disposed between said Diaphragm means and said switch card and having an opening at each array of switching elements for electrically insulating said switching element means and land pattern means from said diaphragm means, and a plurality of switch actuator means, one for each of said arrays of switching elements, for selectively deflecting said diaphragm means through one of said openings in said separator means into electrical contact with each said element of its associated array, whereby actuation of one of said switch actuator means will produce an output signal at said output locations.

7. The keyboard of claim 6 wherein said output locations comprise a plurality of groups of output connectors, one of said groups being uniquely associated with a corresponding switching element from each said array, each said switching element being connected by double sided wiring to one and only one output connector of its associated group.

8. The keyboard of claim 7 further comprising rollover logic means for detecting the presence of positive logic levels at more than one output connector of any of said groups of output connectors.

9. The keyboard of claim 7, further comprising strobe logic means responsive to the output code at said output connector means for detecting that each group of output connectors has a positive logic signal on one of its output connectors.

10. An electronic keyboard apparatus having a plurality of key locations for generating a unique output code for each key, comprising:

elastic diaphragm means comprising a thin sheet of conductive spring material for providing a voltage source, switch card means for generating an output code signal comprising a substrate, a plurality of arrays of switch element means on the surface of said substrate, one said array for each said key location, for defining the code for said each key, a plurality of groups of output connector means for providing the output signal from said switch card means, wiring means for electrically connecting said switch element means and said output connector means with one switch element means from each said array connected to at least one output connector means of each of said groups, separator means for separating said diaphragm means and said switch card means, a plurality of switch actuator means, one for each said key location, for deflecting said diaphragm means through an opening in said separator means into electrical contact with the switch element means of its corresponding array, rollover protection logic means for detecting simultaneous output signals from a plurality of output connector means within a given group, and strobe logic means for detecting that an output signal is present at at least one output connector means within each said group, whereby a valid multibit output character is generated at said groups of output connector means when one and only one switch actuator means is actuated to move said diaphragm means into electrical contact with all of the switch element means of its associated array.

11. The keyboard of claim 2 further comprising strobe logic means responsive to the output code at said pins for detecting electrical contact between said diaphragm and all of the switching elements of an array.

12. The keyboard of claim 8, further comprising strobe logic means responsive to the output code at said output connector means for detecting that each group of output connectors has a positive logic signal on one of its output connectors.