US3732387A - Key switch - Google Patents

Key switch Download PDF

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Publication number
US3732387A
US3732387A US00191915A US3732387DA US3732387A US 3732387 A US3732387 A US 3732387A US 00191915 A US00191915 A US 00191915A US 3732387D A US3732387D A US 3732387DA US 3732387 A US3732387 A US 3732387A
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United States
Prior art keywords
conductors
key
contact
opening
conical surface
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00191915A
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English (en)
Inventor
W Berry
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Addmaster Corp
Original Assignee
Addmaster Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Addmaster Corp filed Critical Addmaster Corp
Application granted granted Critical
Publication of US3732387A publication Critical patent/US3732387A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H1/00—Contacts
    • H01H1/12—Contacts characterised by the manner in which co-operating contacts engage
    • H01H1/14—Contacts characterised by the manner in which co-operating contacts engage by abutting
    • H01H1/24—Contacts characterised by the manner in which co-operating contacts engage by abutting with resilient mounting
    • H01H1/242—Contacts characterised by the manner in which co-operating contacts engage by abutting with resilient mounting the contact forming a part of a coil spring

Definitions

  • ABSTRACT A key switch incorporated with a printed circuit board having conductors thereon and a bearing member loosely fitted in a hole formed between adjacent terminal ends of the conductors.
  • a depressible .key is slideable in the bearing member and has a generally conical surface engaging an expandable toroidal contact spring member which rests on an outwardly tapering surface of the bearing member. As the key is depressed the conical surface thereof expands the spring member downwardly over the surface of the bearing member and into bridging contact with the conductors.
  • Switches have been developed heretofore for use in connection with printed circuit boards to control electronic circuits.
  • control of such an electronic circuit requires a signal of adequate voltage, although the current requirements are generally small. Accordingly, it is necessary that the switch contacts be clean and free from metal oxides which might otherwise increase the resistance of the contacts to a point where the signal will be unreliable. Also, it is essential in many cases that the switch contacts do not produce noise or contact bounce or chatter which may give rise to spurious and unwanted signals.
  • the construction of said switch requires that the end of the conductors in the vicinity of the'switch terminate outside the normal location of the spring.
  • Such construction requires precise location of such terminal ends and the guide means for the key since any lateral movement of the key in any direction might cause undesired contact to be made.
  • the spacing is too great an undue length of key stroke is required to close the switch.
  • the contact spring must engage and ride over the adjacent terminal ends of the conductors and this tends to give rise to contact bounce when the'key is depressed quickly.
  • the present invention represents an improvement over the switch disclosed in the above noted Fordeck Patent and comprises a printed circuit board having an opening therein and two or more conductors thereon terminating at such opening.
  • An annular non-conducting bearing member fits in the opening and sideably guides the lower end of a key member having a tapered actuating portion.
  • the bearing member also normally supports the toroidal contact spring and guides it into contact with the upper surfaces of the conductors just as the key member reaches the bottom of its stroke.
  • a very thin coating of non-oxidizing metal such as gold, may be applied.
  • this coating may be extremely thin, i.e., on the order of 0.00050 inches in thickness, it will insure adequate electrical contact with little or no tendency for the coating to wear.
  • contact bounce is reduced or eliminated regardless of the speed at which the switch is operated.
  • a further feature of the invention resides in the fact that the opening in the printed circuit board, through which the key member extends, need not be precisely located relative to the terminal ends of the conductors.
  • a further feature is that the terminal ends of the conductors need not be spaced from the edge of the opening in the printed circuit board but instead, need only be initially located adjacent the opening. For example, the conductors may initially be terminated anywhere within the area of the desired opening and then such opening may be later drilled or punched.
  • FIG. 1 is a sectional elevation view through a
  • FIG. 2 is a sectional plan view taken substantially on the line 2-2 of FIG. 1.
  • a single key operated switch generally indicated at 11 is illustrated, the latter being incorporated with a printed circuit board 12 of plastic or similar non-conductive material having a pair of conductors l3 and 14 bonded on theupper surface thereof.
  • a large number of such switches can be grouped together on the board 12 to form a keyboard switching assembly.
  • a hole 15 is formed in the board 12 to receive an annular bearing member 16 having a radially extending flange 17 at the upper end thereof.
  • the bearing member 16 is formed of plastic or other non-conductive material and has a bearing opening 18 therein to slideably receive the lower bearing portion 19 of a plastic key member 20, the latter having a key top indicated at 21.
  • the key member 20 has an upper bearing portion 22 of rectangular cross section which is slideably received in a mating bearing 23 formed in an upper key plate 24 suitably supported in fixed relation to the printed circuit board 12.
  • the bearing member 16 may be smaller in diameter than the hole 15 to permit the bearing member to float to enable it to align itself with the bearing 23 even though the hole 15 may be somewhat out of alignment with the bearing 23.
  • a convex-conical surface 25' is formed on the key member 20 intermediate the bearing portions 19 and 22 and forms a shoulder 26 on the bottom thereof which is adapted to limit against the upper surface of the bearing member 16 to arrest depression of the key member 20.
  • a helically wound toroidal contact spring 27 is tensioned over the conical surface 25 and normally rests on the upper surface of the flange 17 of the bearing member 16. Because of its constriction against the conical surface 25, the spring 27 normally maintains the key member 20 in its illustrated raised position wherein a bumper ring 28 of elastomeric material fitted over the bearing portion 22 engages the bottom of the 7 key plate 24. The spring 27 is also effective to raise the key member from depressed position in which case the bumper ring absorbs the shock of arresting the key member in its upper position.
  • a flash coating of gold, platinum or other metal having little or no tendency to oxidize and having a thickness of approximately 0.00050 inches is applied to both the spring 27 and the conductors 13 and 14.
  • the flange 17 of the bearing member 16 has a conical upper surface 29 which terminates in an outer, substantially sharp edge 28.
  • the plane of such upper surface extends coincident with a line 30 which is at right angles to a line 31 extending coincident with the general plane of the conical surface 25.
  • the plastic surface 25 exerts a force against various coils of the spring 27 which is substantially parallel to the plane of the conical surface of flange 17, thus expanding the spring and causing it to move down the conical surface 29 and into contact with the conductors l3 and 14. Due to the sliding action of the spring 27 in moving down the smooth plastic upper surface of flange 17 onto the conductors 13 and 14 and the minimum wiping action of the spring 27 and the conductors l3 and 14, there will be little tendency for the coating of noble metal to wear and there will be no tendency for the contact spring 27 to bounce or chatter.
  • the hole need not be precisely centered over the adjacent ends of the conductors l3 and 14 but may be offset considerably in any direction without affecting the operation of the switch.
  • the adjacent terminal ends of such conductors are preferably enlarged into semi-circular projections 32 and 33, respectively, so that the majority of the coils of the spring will establish contact when the key member is fully depressed.
  • the convex-conical surface 25 enables the contact spring 27 to exert a maximum upward force against the key member 20 when in its illustrated raised position and a minimum upward force when the key member is fully depressed. Although this gives a generally desired key characteristic, the surface 25 could also be made conical or concave-conical with resultant different key characteristics.
  • a key operated switch comprising a flat support of non-conductive material having a pair of conductors on and extending along the upper surface thereof and having flat upper coplanar contact surfaces spaced from each other,
  • a depressible key member extending through said opening and having a generally conical surface thereon
  • said key member being movable at right angles to said support
  • said key member being depressible in said opening whereby to cause said conical surface to expand said contact member radially beyond the upper surface of said annular member and into contact with contact surfaces of said conductors.
  • a key operated switch according to claim 1 wherein a bearing member fits in said opening in said support and has a flange constituting said annular member extending radially over said conductors,
  • said flange tapering outwardly to a substantially sharp edge.
  • a key operated switch according to claim 3 wherein said key member is arrested during depression thereof against the upper surface of said bearing member.

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  • Contacts (AREA)
  • Push-Button Switches (AREA)
US00191915A 1971-10-22 1971-10-22 Key switch Expired - Lifetime US3732387A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US19191571A 1971-10-22 1971-10-22

Publications (1)

Publication Number Publication Date
US3732387A true US3732387A (en) 1973-05-08

Family

ID=22707443

Family Applications (1)

Application Number Title Priority Date Filing Date
US00191915A Expired - Lifetime US3732387A (en) 1971-10-22 1971-10-22 Key switch

Country Status (5)

Country Link
US (1) US3732387A (enrdf_load_stackoverflow)
JP (1) JPS5411564Y2 (enrdf_load_stackoverflow)
FR (1) FR2156515B1 (enrdf_load_stackoverflow)
GB (1) GB1400628A (enrdf_load_stackoverflow)
IT (1) IT949087B (enrdf_load_stackoverflow)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4034177A (en) * 1976-11-19 1977-07-05 Burroughs Corporation Plunger-actuated, lost motion switch with tactile feedback
US4088855A (en) * 1977-02-28 1978-05-09 Korry Manufacturing Co. Keyboard electro-mechanical switch with coil spring contact
US4127752A (en) * 1977-10-13 1978-11-28 Sheldahl, Inc. Tactile touch switch panel
US4145589A (en) * 1976-06-30 1979-03-20 Gnt Automatic A/S Pushbutton arrangement
US4418252A (en) * 1982-04-05 1983-11-29 Daigle Phillip R Key switch assembly
US4772766A (en) * 1986-03-10 1988-09-20 Sirio Panel S.N.C. Di Forzieri G. & S. Push button device for electric contacts or the like, particularly suitable for instrumentation panels

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US959435A (en) * 1909-03-06 1910-05-24 Electric Goods Mfg Company Circuit-closer.
US3206561A (en) * 1961-11-02 1965-09-14 Magnavox Co Expansible multiple contact switch

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
UST959435I4 (enrdf_load_stackoverflow) * 1909-03-06

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US959435A (en) * 1909-03-06 1910-05-24 Electric Goods Mfg Company Circuit-closer.
US3206561A (en) * 1961-11-02 1965-09-14 Magnavox Co Expansible multiple contact switch

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4145589A (en) * 1976-06-30 1979-03-20 Gnt Automatic A/S Pushbutton arrangement
US4034177A (en) * 1976-11-19 1977-07-05 Burroughs Corporation Plunger-actuated, lost motion switch with tactile feedback
US4088855A (en) * 1977-02-28 1978-05-09 Korry Manufacturing Co. Keyboard electro-mechanical switch with coil spring contact
US4127752A (en) * 1977-10-13 1978-11-28 Sheldahl, Inc. Tactile touch switch panel
US4418252A (en) * 1982-04-05 1983-11-29 Daigle Phillip R Key switch assembly
US4772766A (en) * 1986-03-10 1988-09-20 Sirio Panel S.N.C. Di Forzieri G. & S. Push button device for electric contacts or the like, particularly suitable for instrumentation panels

Also Published As

Publication number Publication date
FR2156515A1 (enrdf_load_stackoverflow) 1973-06-01
FR2156515B1 (enrdf_load_stackoverflow) 1974-05-10
JPS4858468U (enrdf_load_stackoverflow) 1973-07-25
JPS5411564Y2 (enrdf_load_stackoverflow) 1979-05-24
GB1400628A (en) 1975-07-16
IT949087B (it) 1973-06-11

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