KEYBOARD SWITCH ASSEMBLY WITH IMPROVED MOVABLE CONTACT HAVING CANTILEVER SUPPORTED CENTRAL MEMBER WITH RADIALLY EXTENDING CONTACT FINGERS

• US 3,777,082 A
• Filed: 09/08/1972
• Issued: 12/04/1973
• Est. Priority Date: 09/08/1972
• Status: Expired due to Term

• Current Assignee: Donnelly Corporation (Magna International Incorporated)
• Original Assignee: Derek J. Hatley, Harold R. Wilson
• Inventors: Hatley, Derek J., Wilson, Harold R.
• Primary Examiner(s): Scott, J. R.
• Application Number:
  US05/287,508
• Time in Patent Office: 452 Days
• Field of Search: 200/5R,5A,159B,166BH,1R,159A,166J
• US Class Current: 200/5.00A
• CPC Class Codes: B41J 5/08 Character or syllable selected by means of keys or keyboards of the typewriter type
• 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 13/785 characterised by the material of the contacts, e.g. conductive polymers
• CPC Class Codes: H01H 2201/026 non precious
• CPC Class Codes: H01H 2203/044 to achieve a predetermined sequence of switching
• CPC Class Codes: H01H 2229/016 Selective etching
• CPC Class Codes: H01H 2239/026 Internal encoding, e.g. validity bit

Abstract

A mechanically operated keyboard with key stations having a multiplicity of electrical switch contacts for providing an encoded electrical data output signal corresponding to and uniquely identifying individual key stations includes an array of movable contacts each corresponding to an individual key station and which are formed in a sheet of conducting material mounted above a corresponding array of fixed contacts to form multiple contact electrical switches for each key station of the keyboard. Each movable contact has a central member suspended to the sheet of conducting material in cantilevered fashion and includes a plurality of peripherally spaced contact fingers joined to the central member such that the contact fingers adjacent the junction of the central member to the conducting sheet will contact associated fixed contacts of a key station only after the remaining contact fingers have come into contact with their associated fixed contacts. An electrical circuit coupled to the contact fingers provides a strobe output signal only when all of the electrical switch contacts associated with a given key station have been actuated as indicated by the closure between the contact finger adjacent the junction of the central member to the conducting sheet and its associated fixed contact.

Claims

1. In a keyboard including a plurality of key stations for providing electrical data signals uniquely identifying each key station as it is actuated, an electrical switch for each key station comprising:

an insulated base member;

an array of fixed electrical contacts positioned in fixed relationship on said base member;

insulative spacing means on said base member adjacent said array of fixed electrical contacts;

a sheet of flexible conducting material supported on said spacing means in spaced relationship to said array of fixed electrical contacts and including an opening therein;

a movable electrical contact positioned within said opening of said sheet, said movable contact including a central member with a plurality of contact fingers positioned in alignment with associated fixed electrical contacts and means coupling said central member to an edge of said sheet adjacent said opening in a manner such that when the key station is actuated, said central member moves in a controlled manner to assure a predetermined contact finger will contact an associated fixed contact last in the sequence of engagement of said contact fingers to said fixed contacts.

2. The apparatus as defined in claim 1 wherein said coupling means comprises an arcuate segment of flexible conducting material having opposite ends coupled to said central member such that said segment circumscribes a portion of said central member, and means for joining an edge of said segment remote from said central member to an edge of said sheet within said opening in a cantilevered fashion such that when the key station is actuated, said central member will initially bend about said joining means and subsequently pivot within said segment at the junction of said opposite ends of said segment to said central member such that the contact finger immediately adjacent said joining means is last-to-make.

3. The apparatus as defined in claim 2 wherein said joining means comprises an arm coupled between said segment and said edge of said sheet;

and wherein said central member and contact fingers thereon, said segment, and said arm are integrally formed in said sheet and are substantially coplanar therewith when the key station is not actuated.

4. The apparatus as defined in claim 1 wherein said means for coupling said central member to said sheet is a substantially Y-shaped member having a pair of ends at one end thereof attached to said central member and circumscribing a portion of said member, and the remaining end attached to said sheet such that when the key station is actuated, said remaining end will initially bend and the central member will then pivot within said Y-shaped member at the junction of said ends of said member to said central member to insure that the contact finger immediately adjacent said remaining end is last-to-make.

5. The apparatus as defined in claim 4 wherein said central member and contact fingers thereon, said Y-shaped member, and said sheet are integrally formed and are substantially coplanar when the key station is not actuated.

6. The apparatus as defined in claim 1 wherein said coupling means comprises an arcuate segment of flexible conducting material positioned within said opening and having opposite ends coupled to said sheet at the Edge of said opening, and a pair of spaced arms of flexible conductive material extending from said arcuate segment to said central member such that said arcuate segment circumscribes at least a portion of said central member and wherein said predetermined contact is positioned on said central member between said spaced arms.

7. The apparatus as defined in claim 1 wherein said coupling means comprises first and second arms of flexible conductive material each having one end joined to said central member in spaced relationship to the other arm and remote ends joined to the edge of said sheet within said opening and in spaced relationship such that when the key station is actuated, said arms will initially bend about said remote end and subsequently said central member will pivot at the junction of said one end of said arms to said central member such that a contact finger between said arms is last-to-make.

8. The apparatus as defined in claim 7 wherein said ends of said first and second arms are narrower than the middle of said arms thereby permitting the bending and twisting of said arm ends to provide the desired motion for said movable contacts.

9. The apparatus as defined in claim 8 in which said first and second arms are aligned in parallel relationship.

10. In a keyboard for developing electrical data signals uniquely identifying each of a plurality of key stations on said keyboard, an electrical switch for each key station including a movable contact for contacting an array of associated fixed electrical contacts coupled to a source of electrical power to provide an electrical data signal at an output terminal of said keyboard when a key station is actuated, said movable contact comprising:

a central member including a plurality of integrally formed contact fingers around the periphery of said central member, said central member formed in a sheet of flexible conducting material mounted in proximity to the array of fixed contacts associated with a key station and circumscribed by said sheet, said central member joined to said sheet by a joining member of flexible conducting material joining said central member to said sheet in a cantilevered fashion such that said central member and contact fingers thereon can be displaced relative to the plane of said sheet in a controlled manner to assure said contact fingers of said movable contact physically and electrically contact said associated array of fixed contacts whereby preselected contact fingers are last in the sequence of engagement to contact associated fixed contacts when the key station is actuated.

11. The movable contact as defined in claim 10 wherein said joining member comprises an arcuate member having one edge coupled to said sheet and a pair of ends coupled to said central member such that said central member is partially circumscribed by said arcuate member.

12. The movable contact as defined in claim 11 wherein said central member, said joining member, and said sheet are integrally formed in a single sheet of conducting material and in substantially the same plane.

13. The movable contact as defined in claim 10 wherein said joining member comprises a pair of arms coupled to said central member at spaced positions on either side of said central member by one end of each arm, said arms having ends remote from the central member joined in spaced relationship to said sheet.

14. The movable contact as defined in claim 13 wherein said central member and contact fingers thereon, said pair of arms, and said sheet are integrally formed in a single sheet of conducting material and in substantially the same plane.

15. The movable contact as defined in claim 14 wherein each end of each of said arms is narrowed to increase the flexibility of the arms at the junction of said arms to said central member and to said sheet.

16. In an electrical-mechanical keyboard for providing electrical data output signals which uniquely identify each key station of the keyboard, and wherein each key statIon comprises an array of fixed electrical switch contacts and a single movable electrical contact which is movable to electrically contact the array of fixed electrical contacts;

a method of providing a signal indicating that each of the fixed contacts of the array of fixed contacts have been contacted by the movable contact comprising the steps of;

suspending the movable electrical contact in a cantilevered fashion above the array of associated fixed electrical contacts;

bending the movable contact toward the array of fixed contacts at an angle thereto until at least one fixed contact is contacted by the movable contact;

pivoting the movable contact such that it is parallel to the plane of the fixed contacts such that one of the remaining fixed contacts contacts an associated contact in the sequence of engagement; and

coupling the last-to-make electrical switch contact to an electrical circuit which responds thereto to provide a signal when the last-to-make contact is closed.