Combined rotary potentiometer and switch

• US 4,081,782 A
• Filed: 08/04/1976
• Issued: 03/28/1978
• Est. Priority Date: 08/04/1976
• Status: Expired due to Term

• Current Assignee: Bourns Incorporated
• Original Assignee: Bourns Incorporated
• Inventors: Hildreth, Bradrick Alan, Wiley, George Richard, Stephens, Donald Harrison
• Primary Examiner(s): Albritton, C. L.
• Application Number:
  US05/711,345
• Time in Patent Office: 601 Days
• Field of Search: 338/162, 338/164, 338/171, 338/172, 338/191, 338/198, 338/200, 338/201, 338/188, 338/184, 338/199
• US Class Current: 338/200
• CPC Class Codes: H01C 10/36 structurally combined with switching arrangements
• CPC Class Codes: H01H 2300/004 Application hearing aid
• CPC Class Codes: H04R 2225/61 Aspects relating to mechanical or electronic switches or control elements, e.g. functioning
• CPC Class Codes: H04R 25/65 Housing parts, e.g. shells, tips or moulds, or their manufacture

Abstract

A potentiometer and switch combination including a rotatable control cap positioned over a potentiometer body to form a housing. The cap is provided with an annular flange which abuts an annular shoulder on the body, either the flange or the shoulder being formed from stiffly flexible, resilient material. The body holds the cap in place by means of a post having a chevron at its upper end which mates with a recess in the cap. The cap is positioned to deform the stiffly flexible, resilient material into frictional sealing relation with its abutting member and thereby seal the interior of the housing. The sealing arrangement also introduces a torque which opposes rotation of the cap. The switch includes a conductive strip held by the body, one portion of the strip forming a first contact and another portion forming a spring detent. A cantilever spring blade which holds a second contact adjacent to and radially inward from the first contact urges the contacts together, while a nonconductive blocking member projects downwardly from the cap to separate the contacts when the switch is off. Rotating the cap moves the blocking member out from between the contacts, permitting them to close, and also causes the spring detent to snap against the blocking member and give the operator a positive switch feel.

The device is particularly suited for use in a hearing aid.

Claims

1. A rotary potentiometer, comprising:

a body portion having an annular shoulder around its periphery,

a resistance element and collector means secured to said body portion,

termination means associated with said resistance element and collector means,

a control cap rotatably positioned over said body portion and forming therewith a housing for said resistance element and collector means, said cap having an annular flange abutting said body portion shoulder,

means securing said cap to said body portion, and

electrically conductive wiper means controlled by rotation of said cap for electrically and mechanically coupling said resistance element to said collector means,

switch means including first and second contact means situate in said control cap,

dowel means for separating said first and second contact means in response to rotation of said control cap,

at least one of said body portion shoulder and cap flange being formed from a stiffly flexible, resilient material, said securing means holding said cap and body portion together with sufficient pressure to deform said stiffly flexible, resilient material and provide a frictional seal between said body shoulder and cap flange, thereby sealing the interior of said housing and introducing a counter torque to rotation of said cap.

2. The potentiometer of claim 1, wherein said body shoulder comprises a stiffly flexible, resilient lip having an upper surface extending outwardly from said body portion at a first, unflexed angle from horizontal, and said annular flange includes an annular inner wall disposed at a second angle to horizontal which is greater than said first angle, said cap being press-fit over said body portion to flex said lip downwardly and establish an annular frictional surface contact between said inner flange wall and said upper lip surface.

3. The potentiometer of claim 2, wherein said lip is formed from nylon.

4. The potentiometer of claim 1, wherein said means securing the cap to the body portion comprises the combination of a boss formed from a stiffly flexible, resilient material and extending downwardly from the underside of said cap, an axial recess extending into said boss from its underside, a post extending axially upward from a base at said body portion, and a downward and outward flaring chevron on said post, said chevron being of slightly greater diameter at its lower edge than the diameter of said recess and lodged in said recess with its lower edge deforming the adjacent boss material to prevent said body portion and cap from separating.

5. The potentiometer of claim 4, wherein said collector means comprises an electrically conductive ring formed integrally with and surrounding the base of said post, and said wiper means comprises an electrically conductive spring means secured to said cap and extending downwardly therefrom to wipe against said resistance element and said ring.

6. The potentiometer of claim 5, said boss having a slot extending thereinto from its underside and offset from said recess, and said wiper spring including a tab extending into said slot with a barb thereon engaging the boss material to secure said wiper spring to said boss.

7. The potentiometer of claim 1, said housing forming an interior chamber, said resistance element and collector means being held in said chamber, and further including a switch means comprising a first switch contact means held in said chamber proximate to a side wall thereof, a second switch contact means, terminals associated with each of said switch contact means, cantilever spring means holding said second contact means adjacent to and radially inward from said first contact means, said spring means urging said second contact means towards said first contact means, and a nonconductive blocking member projecting downwardly from said cap between said first and second contact means, said blocking member being moved out from between said two contact means by rotation of said cap to enable closing of said contact means, and thereafter returning to a position separating said contact means by counter-rotation of said cap.

8. The potentiometer of claim 7, and further including a spring detent formed on said first switch contact means in the rotational path of said blocking member and positioned to be flexed by said blocking member substantially concurrently with switching of said two contact means to produce a positive switch feel.

9. The potentiometer of claim 7, wherein said means securing the cap to the body portion comprises the combination of a boss formed from a stiffly flexible, resilient material and extending downwardly from the underside of said cap, an axial recess extending into said boss from its underside, a post extending axially upward from said body portion, and a downward and outward flaring chevron on said post, said chevron being of slightly greater diameter at its lower edge than the diameter of said recess and lodged in said recess with its lower edge deforming the adjacent boss material to prevent said body portion and cap from separating.

10. In a rotary potentiometer having a housing forming an interior cavity, a resistance element and collector means held in said chamber, a control cap rotatably secured over said chamber, termination means associated with said resistance element and collector means, and means controlled by rotation of said cap for electrically and mechanically coupling said resistance element to said collector means, the improvement comprising a switch means which comprises:

a first switch contact means held in said chamber and spaced from the center thereof, a second switch contact means, terminals associated with each of said switch contact means, cantilever spring means holding said second contact means adjacent to and radially inward from said first contact means, said spring means urging said second contact means towards said first contact means, and a nonconductive blocking member projecting downwardly from said cap between said first and second contact means, said blocking member being moved out from between said two contact means by rotation of said cap to enable closing of said contact means, and thereafter returning to a position separating said contact means by counter-rotation of said cap.

11. The potentiometer of claim 10, said cantilever spring means comprising a flexible, resilient, conductive blade secured to said body portion at one end and extending in a flexed arc around a portion of said chamber, said second switch contact means being integrally formed on said blade at the other end thereof.

12. The potentiometer of claim 10, and further including a spring detent formed on said first switch contact means in the rotational path of said blocking member and positioned to be flexed by said blocking member when said contact means are switched, thereby producing a positive switch feel.

13. The potentiometer of claim 12, said first contact means and spring detent being formed by a single flexible, resilient, conductive strip held adjacent to a side wall of said cavity, the detent portion of said strip being spaced from said cavity wall.

14. The potentiometer of claim 10, said cap being secured to said body portion by means comprising the combination of a boss formed from a stiffly flexible, resilient material and extending downwardly from the underside of said cap, an axial recess extending into said boss from its underside, a post extending axially upward from said body portion, and a downward and outward flaring chevron on said post, said chevron being of slightly greater diameter at its lower edge than the diameter of said recess and lodged in said recess with its lower edge deforming the adjacent boss material to prevent said body portion and cap from separating.

15. In a rotary potentiometer having a body portion, a resistance element and collector means secured to said body portion, termination means associated with said resistance element and collector means, a rotatable control cap positioned over said body portion, and means controlled by rotation of said cap for electrically and mechanically coupling said resistance element to said collector means, the improvement comprising:

means for securing said cap to said body portion, said means comprising the combination of a boss formed from a stiffly flexible, resilient material and extending downwardly from the underside of said cap, an axial recess extending into said boss from its underside, a post extending axially upward from a base on said body portion, and a downward and outward flaring chevron on said post, said chevron being of slightly greater diameter at its lower edge than the diameter of said recess and lodged in said recess with its lower edge deforming the adjacent boss material to prevent said body portion and cap from separating.

16. The potentiometer of claim 15, wherein said collector means comprises an electrically conductive ring formed integrally with and surrounding the base of said post, and said wiper means comprises an electrically conductive spring means secured to said cap and extending downwardly therefrom to wipe against said resistance element and said ring.

17. The potentiometer of claim 16, said collector ring comprising a surface of a collector pin formed in a unitary construction with said post.

18. The potentiometer of claim 16, said boss having a slot extending thereinto from its underside and offset from said recess, and said wiper spring including a tab extending into said slot with a barb thereon engaging the boss material to secure said wiper spring to said boss.