US 3728499 A
One wall, such as the upper wall, of an elongated case of an adjustable electrical control device is provided with a slot extending lengthwise of the case. Disposed in the case lengthwise thereof is a pair of laterally spaced electrical elements engaged by electric contact means carried by a slide extending through the slot. A bar above the case extends lengthwise of it and is provided with longitudinally spaced recesses. The slide is moved along the case by an actuator connected to it, and either the slide or the actuator carries spring-pressed means normally projecting into one of the bar recesses, whereby the slide and actuator can be indexed along the bar.
Description (OCR text may contain errors)
United States Patent 9] Bang et a1.
 ADJUSTABLE ELECTRICAL CONTROL DEVICE WITH LONGITUDINAL INDEXIN G FOR SLIDE SWITCH  Inventors: Mogens W. Bang, Ridgway; Richard P. Kronenwetter, St. Marys, both of  Assignee: Stackpole Carbon Company, St.
 Filed: Dec. 14,1971
 Appl' No.: 207,902
UNITED STATES PATENTS Lewandowski ..200/ l 6 F Farrell ..200/ l 6 C [451 Apr. 17, 1973 Primary Examiner.l. R. Scott Attorney-Brown, Murray, Flick & Peckham ABSTRACT One wall, such as the upper wall, of an elongated case of an adjustable electrical control device is provided with a slot extending lengthwise of the case. Disposed in the case lengthwise thereof is a pair of laterally spaced electrical elements engaged by electric contact means carried by a slide extending through the slot. A bar above the case extends lengthwise of it and is provided with longitudinally spaced recesses. The slide is moved along the case by an actuator connected to it, and either the slide or the actuator carries springpressed means normally projecting into one of the bar recesses, whereby the slide and actuator can be indexed along the bar.
8 Claims, 1 1 Drawing Figures PATENTEU j 3.728.499
I SHEET 2 OF 4 3y am mm waoam A TTORA/Efi ADJUSTABLE ELECTRICAL CONTROL DEVICE WITH LONGITUDINAL INDEXING FOR SLIDE SWITCH Linear motion electrical control devices, such as potentiometers and switches, are often adjusted by a sliding member that can be moved lengthwise of the case. In many instances this is all that is wanted, but in other uses it may be desirable to be able to index the slide along the case to certain predetermined positions and yet be able to use the same case and basic construction with a minimum of changes.
It is an object of this invention to provide a linear motion electrical control device with means permitting indexing of the movable contact. Other objects are to provide indexing means which can readily be applied to existing potentiometers and switches, and which can support a bezel or frame to improve the appearance of the panel to which the device is attached.
The invention is illustrated in the accompanying drawings, in which FIG. 1 is a front or plan view of the preferred embodiment;
FIG. 2 is a side view thereof;
FIG. 3 is an end view;
FIG. 4 is a rear or bottom view;
FIG. 5 is a central longitudinal section taken on the line V-V ofFIG. 1;
FIG. 6 is an enlarged cross section taken on the line Vl-VI of FIG. 1;
FIGS. 7 and 8 are enlarged fragmentary longitudinal sections taken on the lines VII-VII and VIII-VIII, respectively, of FIG. 5;
FIG. 9 is a fragmentary front or plan view of a modification, partly broken away;
FIG. 10 is a fragmentary longitudinal section taken on the line XX of FIG. 9; and
FIG. 11 is a cross section taken on the line XIXI of FIG. 10.
Referring to FIGS. 1 to 8 of the drawings, the long rectangular case 1 of a linear motion adjustable electrical control device, such as a potentiometer or switch, may be formed from any suitable material. The case preferably is made from two half-sections molded from a plastic and having meeting edges extending from front to back across the end walls of the case and lengthwise along its back or base. Inside the case there is a pair of laterally spaced electrical elements 2 and 3 extending lengthwise of it. In a potentiometer, these would be a collector and a resistance element, while in a switch at least one of the strips would be provided with fixed contacts having terminals 4 extending out of the back or bottom of the case. The particular form of elements 2 and 3 is not important to this invention, but between them there is movable contact means, such as one or more bridging contact, that engages both. The bridging contacts 6 are carried by a slide 7 that is slidably mounted in a central slot 8 extending lengthwise of the case in its front or top wall. The bridging contacts may be spring wires straddling the slide in vertically spaced horizontal grooves. The slide also has laterally opening grooves in its opposite sides receiving the side walls of the slot to hold and guide the slide. For convenience only, the case will be assumed to be positioned with its slotted wall uppermost, but whether that is true in practice or the case is on its side or one end is immaterial as far as the invention disclosed and claimed herein is concerned. The slide extends above the upper wall of the case.
In accordance with this invention, brackets 10 are attached to the opposite ends of the case, each bracket extending above and below the case and having parallel tongues 11 that straddle the case and fit in grooves in its opposite sides to hold the bracket in place. The brackets are also useful for holding the two halves of the case together. The lower ends of the brackets may be provided with integral tabs 12 for insertion in a printed circuit board or other type of panel in order to mount the device in the desired location. The upper ends of the two brackets support a bar 13 that extends lengthwise of the case parallel to its upper wall, from which it is spaced. Each end of the bar is provided with a pair of openings, through which split lugs 14 project from the tops of the brackets. The lugs are staked to hold the bar firmly on top of the brackets.
Slidable along the upper surface of the bar is an actuator 16 that has an upwardly extending knob 17 for moving it. The actuator is provided at its opposite ends with downwardly extending hook portions 18 that straddle the bar in engagement with its opposite edges. The lower ends of the hooks hook under laterally projecting portions 19 of opposite sides of the slide. The upper ends of these projecting portions may also engage the opposite edges of the bar. The actuator and slide are rigidly connected together by the hooks so that when the actuator is moved along the bar it will move the slide with it.
It is a feature of this invention that the slide and actuator can be held in any one of a number of predetermined positions along the case to provide indexing of the bridging contacts 6. Accordingly, as shown in FIGS. 2 and 5, the bottom of the bar is provided with a plurality of longitudinally spaced indexing recesses 21 that can be made in various ways, but preferably by vertically deforming longitudinally spaced portions of the bar to provide recesses between them having inclined end walls. The deforming can be accomplished by slitting the bar at intervals, and pressing the slit portions downwardly. The slide carries spring-pressed means to project into these recesses. Thus, the portion of the slide above the case is provided with a downwardly opening socket 22, in which there are a pair of balls 23 in positions to project into two of the bar recesses above them. The balls are urged upwardly into the recesses by a central coil spring 24 that en'- gages the bottom of a ball positioner midway between the ends of the latter. As shown in FIG. 5, this positioner is a small strip 25 that extends down opposite sides of the coil spring to inclined end portions on which the balls rest.
When the actuator is moved by its knob along the bar, the balls slide or roll along the lower surface of the bar from one pair of recesses to the next. The movement of the actuator forces the balls down against the resistance of the coil spring as they leave a pair of recesses, but as soon as the balls reach the next pair the spring and positioner raise them again. If the actuator then is released, the balls will hold it against accidental displacement from that position, but it can be moved further in either direction by applying a small amount of pressure to the actuator to force the balls out of the recesses. Consequently, the slide can be indexed along the case and will remain in any position in which the omitted and the slide replaced by one having its own knob for moving it along the case.
In the modification shown in FIGS. 9 to 11 the indexing bar takes the form of a channel 30, the opposite ends of the side flanges of which project beyond the web of the channel. The ends of the web abut against the inner surfaces of brackets 31 secured to the opposite ends of the case 32, while the projecting ends of the channel flanges extend through parallel notches 33 in the upper ends of the brackets. The flange projections are held in the notches by staking over them a central projecting portion 34 of each bracket between its notches. Each bracket may be held in place like the ones first described or, as shown in FIG. 9, by providing it with side flanges that straddle the adjoining end portion of the case and have outwardly offset portions 35 inturn'ed ends projecting into vertical grooves 36 in the case. The brackets are slid vertically into place on the case.
Slidable along the channel bar is an actuator 40 that has a passage 41 through it, through which the bar extends. The actuator engages the opposite sides and the top and bottom of the bar and has a central longitudinal portion 42 that extends down into the channel. To connect the actuator and slide together, they are provided with interengaging tongues and slots. Preferably, the bottom of the actuator is provided with a pair of laterally spaced tongues 43 that extend down into slots 44 in the opposite sides of the exposed portion of the slide, as shown in FIGS. and 11. Consequently, when the actuator is moved along the bar, the slide is moved with it.
To permit the slide and actuator to be held in any one of a number of predetermined positions along the case to provide indexing, the web of the channel bar is provided with a plurality of longitudinally spaced indexing recesses that can be made most easily by punching holes 46 in it. The actuator carries springpressed means to project into these recesses or holes. Thus, the actuator may be provided midway between its ends with a recess or bore 47 extending upwardly through its central portion 42 and up into a stem 48 on the actuator. Disposed in the lower end of this bore is a ball 49 that is pressed down against the channel web by means of a coil spring 50. When the actuator is moved along the bar, the ball slides or rolls along the adjoining surface of the bar until it is forced down into one of the holes 46. If the actuator then is released, the ball will hold it against accidental displacement from that position, but it can be moved further by applying enough pressure to cause the ball to ride up the edge of the hole onto the flat area of the bar between that hole and the next one. Consequently, the slide can be indexed along the case and will stay in any position in which the ball is allowed to project into an indexing hole in the bar.
The stem 48 of the actuator can extend through a slot 52 in a panel 53 so that the actuator can be operated from the opposite side of the panel. To improve the appearance of the panel, a frame member or bezel 54 may be provided that will frame the edge of the panel slot, extend through it and fit onto the control device behind the panel. This bezel is provided with a slot 55 overlying the channel bar and the slot in the case. The bezel overlaps the panel at the sides and ends of the panel slot and is provided with flanges 56 that extend through that slot and frictionally engage the adjoining end portions of the brackets. The bezel can be held tightly against the front of the panel by lugs 57 projecting from the outer surfaces of its flanges. As shown in FIG. 11, these lugs have inclined outer surfaces that permit them to be pressed through the panel slot until they can snap over its inner edges and hold the front of the bezel tightly against the panel. The stem on the actuator extends through the bezel slot 55 and its appearance may be improved by pressing a more decorative knob 58, provided with a stem-receiving opening, onto the stem. This knob is used to move the actuator.
According to the provisions of the patent statutes, we have explained the principle of our invention and have illustrated and described what we now consider to represent its best embodiment. However, we desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as speciflcally illustrated and described.
1. An adjustable electrical control device comprising an elongated case having an upper wall provided with a slot therethrough extending lengthwise of the case, electrical elements disposed in the case along opposite sides thereof, a slide member extending through said slot and movable lengthwise thereof, electric contact means carried by the slide between said elements in engagement therewith, a bar extending lengthwise of the case and provided with a plurality of longitudinally spaced recesses, supporting means rigidly secured to the case and bar holding the bar above said slot, an actuator member movable lengthwise of the bar and connected to the slide for moving the slide along the case, and spring-pressed means carried by one of said members and normally projecting into one of said recesses, whereby said members can be indexed along the bar.
2. An adjustable electrical control device according to claim 1, in which said actuator member is provided with hooks straddling the bar and hooked onto the slide member.
3. An adjustable electrical control device according to claim 1, in which said slide member is provided with a plurality to claim 1, in which said slide member is provided with a plurality of vertically spaced horizontal grooves in its sides and ends, and said electric contact means are spring wires disposed in said grooves and projecting therefrom into engagement with said electrical elements.
4. An adjustable electrical control device according to claim 1, in which said bar-holding means include brackets attached to the opposite ends of the case and extending above it, the upper ends of the brackets being provided with portions holding the ends of said bar on the brackets.
5. An adjustable electrical control device according to claim 4, including a frame member above said bar and projecting beyond the sides and ends thereof, the frame member being mounted on the upper ends of the brackets and provided with a longitudinal slot above with a longitudinal tubular passage receiving said bar and with a recess extending upwardly from said passage, said spring-pressed means being disposed in said actuator recess and engaging the upper surface of the bar.
8. An adjustable electrical control device according to claim 7, in which said bar is an upwardly opening channel, and said actuator has a central portion extending down into the channel, said actuator recess extending up through said central portion.