US3588779A

US3588779A - Linear motion variable resistance control

Info

Publication number: US3588779A
Application number: US876501A
Authority: US
Inventors: Charles Richard Goerg
Original assignee: Globe Union Inc
Current assignee: Globe Union Inc
Priority date: 1969-11-13
Filing date: 1969-11-13
Publication date: 1971-06-28
Anticipated expiration: 1988-06-28
Also published as: JPS4817819B1; GB1284664A; FR2071899A5

Abstract

THE CHANNEL-SHAPED HOUSING OF A LINEAR MOTION VARIABLE RESISTANCE CONTROL IS PROVIDED WITH A CLOSED OR UNSLOTTED TOP WALL AND A DIELECTRIC BASE, TO WHICH THE RESISTANT AND CONDUCTIVE ELEMENTS ARE MOUNTED, IS DISPOSED IN THE HOUSING SO AS TO DEFINE PARALLE, ELONGATED OPENINGS BETWEEN THE HOUSING SIDEWALLS AND THE LONGITUDINAL EDGES OF THE BASE. A CARRIER BLOCK CARRYING THE BRIDGING CONTACT IS PROVIDED WITH SIDE MEMBERS WHICH EXTEND THROUGH THESE OPENINGS AND A SLIDER, GUIDED BY THE EXTERIOR OF THE HOUSING, IS OPERABLY ATTRACHED TO AT LEAST ONE OF THE CARRIER BLOCK SIDE MEMBERS.

Description

United States Patent Inventor Charles Richard Goerg Milwaukee, Wis.

Appl. No. 876,501

Filed Nov. 13, 1969 Patented June 28, 1971 Assignee Globe-Union Inc.

Milwaukee, Wk.

LINEAR MOTION VARIABLE RESISTANCE CONTROL 8 Claims, 5 Drawing Figs.

US. Cl 338/183, 338/184 Int. Cl. H016 9/02 Field ofseal'ch 338/183,

I76, 184, 178, 179, I80, l8l, 182, 199

[56] References Cited UNITED STATES PATENTS 2,242,327 5/1941 Rubenstein..... 338/183 3,412,36l [1/1968 Lovejoy et al. 338/l83X Primary Examinerl.ewis l-l. Myers Assistant Examiner-D. A. Tone Attorneys-John Phillip Ryan, Glenn A. Buse, Donald D.

Benton and David T. Terry ABSTRACT: The channel-shaped housing of a linear motion variable resistance control is provided with a closed or unslotted top wall and a dielectric base, to which the resistant and conductive elements are mounted, is disposed in the hous-- ing so as to define parallel, elongated openings between the housing sidewalls and the longitudinal edges of the base. A carrier block carrying the bridging contact is provided with side members which extend through these openings and a slider, guided by the exterior of the housing, is operably attached to at least one of the carrier block side members.

LINEAR MOTION VARIABLE RESISTANCE CONTROL BACKGROUND OF THE INVENTION 1 Field of the Invention This invention relates to a variable resistance control and, more particularly, to a variable resistance control having a linear motion.

2. Description of the Prior Art Variable resistance controls having resistance and conductive elements disposed in an elongated, channel-shaped housing with a slider carrying a bridging contact in wiping engagement with the resistance and conductive elements are well known. Variable resistance controls of this type, exemplified by U.S. Pat. Nos. 2,242,327 (Rubenstein) and 3,412,361 (Lovejoy et al.), typically are provided with an elongated, longitudinal slot in the top wall of the housing through which slider actuation means project. In some applications, the exposure of the resistance and conductive elements resulting from this slot is especially undesirable. For instance, variable resistance controls of this type have been considered for use on television sets for manual and/or remote operation. For such use, the control is mounted for ready access to operate. When so positioned, the slot of the prior art devices permit the insertion of foreign objects into contact with the resistance and conductive elements, thereby presenting a potential electrical shock hazard to children who might insert such objects through the opening. Also, the slot permits the ingress of deleterious foreign matter directly onto the resistance and conductive elements.

Various means, such as movable dust shields, have been suggested for closing the slot in order to prevent this internal exposure. Generally, these means increase the cost and complexity of the manufacturer and assembly of the control. These means also usually increase the slider friction with resultant uneven operation of the device.

SUMMARY OF THE INVENTION A primary object of this invention is to provide a simple, inexpensive linear motion variable resistance control protected against the direct entrance of foreign objects onto the resistance and conductive elements.

Another object of this invention is to provide such a linear motion variable resistance control that does not have a slotted housing for accommodation of the slider actuation means.

A further object of this invention is to provide a linear motion variable resistance control with minimum sliding friction.

A still further object of this invention is to provide a linear motion variable resistance control having limited rocking movement of the slider during actuation.

In accordance with this invention, the variable resistance control has an elongated, channel-shaped housing with a closed or unslotted top wall and a pair of sidewalls. A dielectric base, to which the resistance and conductive elements are mounted, is disposed inside the housing as the bottom thereof with the outside longitudinal edges of the base being in spaced relationship with the housing sidewalls so as to define parallel, elongated openings therebetween. A carrier block carrying a bridging contact in wiping engagement with both the resistance and conductive elements is provided with side members which extend outwardly through these openings. A slider disposed about the exterior of the housing and guided thereby is operably attached to at least one of the carrier block side members. Preferably, the carrier block, which is most preferably made from a plastic material, is provided with a shoulder in sliding engagement with the top surface of the base and guide means in sliding engagement with the underside of the housing top wall to limit any rocking movement when the slider is actuated, i.e., when a longitudinal force is applied thereto. Preferably, the slider is provided with guide means in slidable engagement with the exterior of the housing sidewalls to further minimize binding of the control during operation.

BRIEF DESCRIPTION OF THE DRAWING taken along DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. l-5, a variable resistance control constructed in accordance with this invention is illustrated. The

variable resistance control, generally designated 10, comprises an elongated, channel-shaped housing 12, formed from a single piece of suitable material, such as stamped metal or molded plastic, a dielectric base 14, a slider drive 16, and a carried block 18 carrying sliding spring contacts 20. Housing 12 includes a closed or unslotted top wall 22 and a pair of

sidewalls

24 and 26 integral with the top wall and projecting downward therefrom. Housing 12 is secured to base 14 by end tabs .28, extending downwardly from the end portions of

sidewalls

24 and 26, which are folded laterally over the base 14. Ears 30 and 32, integral with top wall 22 and extending upwardly therefrom, are provided for attachment of control 10 to a mounting panel (not shown). These ears are insertable into slots provided in such a mounting panel and are either folded over or twisted to secure the control 10 to the panel. The control also can be attached to the mounting panel in any other conventional manner such as with tap screws.

Base 14 includes an elongated resistance element 34 having an overlaying strip of carbonaceous or equivalent resistance film 36 and an elongated conductive element 38, preferably in the form of an elongated strip of highly conductive material (such as a silver-plated metal) secured to the top surface 13 of base 14.

Terminals

40, 42 and 44 are electrically connected to resistance element 34 and conductive element 38, respectively, and are secured to the bottom surface of base 14 by rivets 46. As shown in FIG. 4, rivets 46 extend through base 14 to serve the double function of securing the resistance element 34, conductive and

terminals

40, 42 and 44 to base 14 and to electrically connect the resistance and conductive elements to their respective terminals. Other conventional mounting means such as an adhesive, and other conventional electrical connecting means, such as solder, can be used for this purpose. Although the resistance means is shown as a separate element 34, it can be provided in the form of a striplike resistance film or coating applied directly onto the top surface 13 of the dielectric base 14. When base 14 is assembled into housing 12 (FIGS. 2 and 3), there are parallel, elongated openings 25 defined between longitudinal edges 14a and the interior of

housing sidewalls

24 and 26 through which carrier

block side members

64 and 66 extend as described hereinafter.

Slider drive 16, configured to encompass the outer surfaces of housing 12, includes an operating shank 48 to which a knob (not shown) or other operating means is attached, a pair of spaced

vertical members

50 and 52, and a pair of

tangs

54 and 56 which are integral extensions of

vertical members

50 and 52, respectively.

Vertical members

50 and 52 include a plurality of integral protuberances or ribs 58 which slidably engage the outer surfaces of

walls

24 and 26 of housing 12. These protuberances 58 act as guide means in providing minimum area of contact between slider drive 16 and housing 12 thereby minimizing friction as the slider bar is operated. The friction can be further minimized by fabricating slider drive 16 from a plastic material such as polymers of propylene, ethylene, acetal and the like.

Carrier block 18, formed from an insulating material, preferably a plastic material, includes a top wall 60 having a plurality of hemispherically-shaped nubs 62 integral with the upper surface thereof which ride in contact with the underside of top wall 22 of housing 12, a pair of

side members

64 and 66 integral with the top wall 60, projecting downwardly therefrom and extending through the elongated opening 25 between the longitudinal edges 14a of the base 14 and

housing sidewalls

24 and 26 and a plurality of

nibs

68, 70 and 72 integral with the top wall60. Each side member of carrier block includes a lower flange section 74 having a slot 76 into which tangs 74 and 76 into which tangs 54 and 56 of the slider drive 16 are inserted and an integral shoulder 78 which rides on the top surface 13 of base 14.

Tangs

54 and 56 are dimensioned so that they are slightly larger than slots 74 to provide a press fit.

The

sidewalls

24 and 26 of housing 12, the

side members

50 and 52 of carrier block 18 and base 14 are dimensioned so that there is a minimum of clearance between the inside of the housing and the outer surface of the side members and between the outside edge of the base and inside surfaces of the side members. The combined effect of the guiding engagement between protuberances 58 of slider drive 16 and outer surfaces of walls 24.and 26, between nubs 60 on carrier block 18 and the underside of the top wall 22 of the housing 12, and between shoulders 78 of carrier block 18 along with a minimum clearance between the

side members

64 and 66 of carrier block 18 and the longitudinal edges 14a of base 14 prevents any appreciable rocking of the carrier block or slider during actuation thereof yet insures free sliding movement. Binding or jerky motion of the slider drive is thereby precluded. As indicated above, carrier block 18 preferably is constructed from a plastic material, such as polymers of propylene, ethylene, acetal and the like, which further minimizes the friction and insures free sliding motion.

Carrier block 18 carries a bridging contact which is in wiping engagement with both the resistance and conductive elements. Bridging contact 20, preferably formed from a spring metal ribbon, is attached to carrier block by

press fitting nibs

68 and 70 into apertures (not shown) in the base thereof. After installation,

nibs

68 and 70 can be deformed, if desired, to insure a fixed connection. If carrier block 18 is constructed from a plastic material, this deformation can be effected by the'simultaneous application of heat and light pressure. Nib 72, which is slightly longer than

nibs

68 and 70, serves as a pilot to assist in the alignment of

nibs

68 and 70 with their respective apertures in the base of the bridging contact during assembly of the bridging contact onto the carrier block. The bridging contact 20 is provided with a plurality of downwardly inclined spring fingers or tines 82, the lower ends of which slidably press against the resistance and contact elements. To assure good contact, bridging contact 20 is provided with two or more tines for each element.

From the above description, it can be seen that this invention provides a variable resistance control with a closed or unslotted top which prevents the external insertion or direct ingress of foreign objects onto the resistance and conductive elements. Also, the novel structure of the slider drive and carrier block provides a control capable of free sliding motion with a minimum of binding or jerky motion. In addition, the novel structure of the control allows simplified and inexpensive fabrication and assembly techniques.

Iclaim:

1. A linear motion variable resistance control comprising:

an elongated, channel-shaped housing having a closed top wall and a pair of sidewalls;

a dielectric base having longitudinal edges and a top surface disposed inside said housing, said longitudinal edges being in spaced relationship with said sidewalls so as to define parallel, elongated openings therebetween;

a carrier disposed within said housing having side members extending outwardly through said openings and guided by said sidewalls and said edges;

spaced parallel resistor and collector elements mounted on the top surface of said base and extending lengthwise thereof; terminals connected to said resistance and conductive elements and said base;

a bridging contact attached to said carrier and insulated from said housing in wiping engagement with both of said elements; and

a slider disposed exteriorly of said housing and operably attached to at least one of said side members.

2. The control according to claim 1 wherein the slider includes spaced, vertical portions guided by said sidewalls and connected to the side members of the carrier.

3. The control according to claim 2 wherein the carrier side members are provided with a shoulder in sliding engagement with the top surface of the base.

4. The control according to claim 3 wherein the carrier includes a top portion having a first guide means in sliding engagement with the interior of the top wall of the housing which cooperate with said flanges to limit the rocking movement of the carrier when a longitudinal force is applied to the slider.

5. The control according to claim 4 wherein said vertical portions of the slider are provided with integral tangs which are press fitted into slots provided in the side members of the carrier.

6. The control according to claim 5 wherein said vertical portions of the slider are provided with second guide means in sliding engagement with the exterior of said sidewalls.

7. The control according to claim 6 wherein said first guide means comprise nubs integral with the top surface of said carrier.

8. The control according to claim 7 wherein said second guide means comprise vertical ribs integral with said vertical portion of the slider.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,588,779 Dated June 28, 1971 Inventor(s) Charles Richard GOERG It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 10, after 4-4 "of" should be in- Column 2, line 21, "carried" should be carrier-- Column 2, line 45, after "34, conductive" insert --element 38-- Column 3, line 10, delete "

tangs

74 and 76 into which" Column 3, line 42, "light should be -slight-- Signed and sealed this 6th dav of June 1972.

(SEAL) Attest:

EDWARD M.F'LETCHER,JR. ROBERT GOT'I'SGHALK Attesting Officer Commissioner of Patents FORM po'wso "0459] USCOMM-DC 6037B-P59 a U 5 GOVERNMENY PRINlNG OFFICE 9.9 D356]3l