Dimmer Switch With Linearly Movable Control

Abstract

A dimmer switch is provided with a linearly moving slider knob which is attached to a linearly moving potentiometer. The potentiometer is connected to the control circuit of a triac device to adjust the firing angle of the triac, thereby to control the dimming of the light. The dimmer switch is placed in a conventional wall box and is connected to the available wiring circuit. A switch connected in series with the device terminals is operated by the linearly moving slider when the switch reaches an end position in its travel.

Description

SUMMARY OF THE INVENTION

This invention relates to voltage control devices, such as lamp dimmer devices, and more specifically relates to a dimmer switch having a linearly moving control knob which controls lamp output, and which operates a switch in series with the main load circuit to an open position at one end of its linear movement.

Solid state dimmer switches are well known, and are shown, for example, in patents such as U.S. Pat. No. 3,422,309 to Spira and Licata, assigned to the assignee of the present invention, and U.S. Pat. No. 3,103,618 to Slater. In such prior devices, a rotary knob is provided to control light output by rotating the rotary wiper arm of a conventional rotary adjustable resistor, such as a potentiometer, connected in a firing control circuit of a solid state device.

In accordance with the present invention, a dimmer switch is formed which uses a linearly moving control element rather than a rotary control element. Thus, a linearly disposed potentiometer is arranged to control the firing of a control circuit which may be of conventional design. A switch wall plate having an elongated opening then permits access to a linearly movable control knob or slider to adjust the firing circuit potentiometer.

In order to provide electrical isolation of the main wiring circuit and the load, the present invention further incorporates a switch which is operated to an open position by the linearly moving slider when the slider reaches a predetermined open or "off" position.

Further, in accordance with the invention, the mounting plate may form a heat sink. This mounting plate may be a generally flat plate having guide means extending from its surface for guiding the movable slider knob. In one embodiment, the mounting plate may have at least a pair of spaced fins facing outwardly of the switch box which is to receive the switch of the invention. These spaced fins then define a guide surface for guiding the motion of the sliding control knob.

As a further feature of the invention, the stroke of the linearly moving potentiometer handle may be equal to or less than the length of the conventional slot in a wall plate which covers a conventional wall box. Thus, conventional switches can be replaced by the novel switch of the invention and the same wall plate can be used to cover the switch using a linearly moving control knob after its installation in the existing wall box.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of one embodiment of the present invention.

FIG. 2 is a plan view of the front of the heat sink of FIG. 1.

FIG. 3 is an end view of the heat sink of FIG. 2.

FIG. 4 is an enlarged view of a snap-off groove and engaging teeth to hold protrusions of the escutcheon, thereby to hold the escutcheon on the heat sink of FIGS. 2 and 3.

FIG. 5 is a plan view of the back of the slider used in FIG. 1.

FIG. 6 is a cross-sectional view of FIG. 5 taken across section line 6 -- 6 in FIG. 5.

FIG. 7 is a longitudinal cross-sectional drawing of the assembled device of FIG. 1.

FIG. 8 is a cross-sectional drawing of FIG. 7 taken across section line 8 -- 8 in FIG. 7.

FIG. 9 is a circuit diagram of the circuit formed by the device of the invention.

FIG. 10 is a plan view of the rear of a second embodiment of the heat sink of the invention.

FIG. 11 is a cross-sectional view of FIG. 10 taken across section line 11 -- 11 in FIG. 10.

FIG. 12 is an enlarged detail of one of the slider-receiving fins of FIG. 11.

FIG. 13 is a plan view of the front of the slider to be used with the plate of FIGS. 10 and 11.

FIG. 14 is a side view of the slider of FIG. 13.

FIG. 15 is a front plan view of the escutcheon or front plate cover to be used in connection with the mounting plate and slider arrangement of FIGS. 10 to 14.

FIG. 16 is an end view of the escutcheon of FIG. 15.

FIG. 17 is a side view of the escutcheon of FIG. 15.

FIG. 18 is an enlarged detail view of one of the snap connectors secured to the escutcheon of FIG. 15.

FIG. 19 is an end view illustrating the assembly of the main mounting plate slider escutcheon of FIGS. 10 to 18, in combination with a switch having a linear potentiometer adjustment means.

FIG. 20 is a perspective view of a further embodiment of the mounting plate of the invention in which a slider guide track is formed by stamped projections in a flat mounting plate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, FIGS. 1 to 4 show a heat sink 10 which may be an extruded aluminum member having a plurality of fins extending from a flat rear surface. When mounted in a wall box, the fin sections face outwardly from the wall. The use of such a heat sink for use in a wall switch, or the like, which is to be mounted into a wall box, permits improved cooling of electrical components in thermal contact with heat sink 10.

The heat sink illustrated in the drawing contains twelve fins 11 to 22. Fins 15 to 18 are shown as having equal heights which are shorter than the heights of fins 11 to 14 and 19 to 22 which themselves are equal. As will be later seen, the aligned tops of fins 15 to 18 form a guide surface for slider 23 (FIGS. 1 and 5 to 8), while the opposing surfaces of fins 14 and 19 above the tops of fins 15 to 18 serve as side guides for slider 23. If desired, the opposing surfaces of fins 13 and 14 and fins 19 and 20 may be grooved, to define means for receiving a screw or an escutcheon protrusion which may be located anywhere along the length of the space between these pairs of fins. Thus, grooves for holding the mounting screws (or plastic extensions) of an escutcheon or cover plate, such as the cover plate 30 shown in FIGS. 1, 7 and 8, and specifically screws 31 and 32 in FIG. 8, may be threaded directly into the heat sink 10 with substantial misalignment being permitted between the cover plate 30 and heat sink 10 by virtue of the elongated screw receiving channels.

In order to mount the heat sink 10 within a conventional wall box, it is necessary to provide screw receiving openings in the heat sink. To this end a plurality of openings, including openings 40, 41, 42 and 43, which are elongated in a direction transverse to the elongated axis of heat sink 10, are provided. Note that portions of the fins which are adjacent to openings 40 to 43 are removed to permit the formation of openings through the flat rear surface of the heat sink 10 and to permit access to the screws passing through these openings. These various openings, for example, openings 41 and 42, may serve to receive conventional mounting screws which normally mount a conventional switch in a wall box and have a standard spacing for this purpose. The heat sink 10 may further have break-off notches, shown, for example, as the notch 45 in FIG. 4, whereby the outer two fin sections 11 and 12 and/or 21 and 22 may be snapped off from the heat sink 10, where the wall box space requirements require a narrower plate type member. The manner in which these sections allow mounting of the assemblies in different size wall boxes is further described in copending application Ser. No. 184,681 filed Sept. 29, 1971, in the name of Joseph Licata, assigned to the assignee of the present invention.

The heat sink is then completed by the formation of various mounting openings which might be required and which will be later described, and by the formation of an elongated slot 50, best shown in FIGS. 2 and 3, which extends between the central regions of fins 16 and 17. Slot 50 receives the elongated operating member 51 of a linearly adjustable potentiometer 52. Thus, in FIGS. 1, 7 and 8, there is shown the potentiometer 52 which may be of the slide type, which is a potentiometer in which the movable wiper arm is linearly movable through the linear movement of operating member 51.

Potentiometer 52 is provided with two end mounting brackets 53 and 54 with upwardly extending tabs 55 and 56, respectively. The tabs 55 and 56 are inserted through mounting openings 57 and 58, respectively, of the heat sink 10 and are inwardly bent, thereby to secure potentiometer 52 to the heat sink 10. Note that a sliding cam arm 60, which is an L-shaped member having an elongated aperture 61 in its upper section, is arranged over the slider 51 before potentiometer 52 is mounted to heat sink 10. As will be described more fully hereinafter, the cam arm 60 travels with operating arm 51 of potentiometer 52 and is used to actuate a switch which is in series with the line containing the control device.

The rear surface of potentiometer 52 is provided with extending terminal members, two of which are shown in FIG. 1 as terminal members 70 and 71. These terminal members are connected mechanically and electrically to suitable openings in a suitable insulation panel 80, which is used as a support for the various electronic components and for the switch mechanism, to be later described, which are used in connection with the dimmer switch arrangement.

One element of this control circuitry is a suitable controllably conductive means, which could consist of a pair of anti-parallel connected controlled rectifiers or a triac device, mounted in thermal connection with the heat sink 10 so that relatively high currents can be carried. Typically, the controllably conductive device 81 can be a triac as shown in FIG. 8, which is connected directly to the base of the heat sink 10. If desired, a thin insulation layer can be interposed between device 81 and the heat sink if electrical isolation of the two elements is needed. Suitable electrical connections are then made between the various electronic components, such as the members 90 to 95, shown in FIG. 1 and partly in FIG. 8 so that an operable dimmer switch arrangement can be formed. This circuitry is very generally shown in FIG. 9 when using anti-parallel connected controlled rectifiers for the controllably conductive device, where the circuit may be of the type shown, for example, in U.S. Pat. No. 3,422,309 to Spira and Licata. Thus, the control circuitry may be used for the control of anti-parallel connected controlled rectifiers 81 and 100 from a control circuit 101, which has an adjustable output depending upon the adjustment of the adjustable resistor or potentiometer 52.

As indicated by the dotted line 102, control circuit 101 is operated by the energy of the voltage applied to the two input leads 103 and 104 of the device and is further coupled to the potentiometer 52. Note further that the entire device is provided only with the two main leads 103 and 104 so that it can be directly wired into existing conventional home wiring circuits. The wires 103 and 104 are shown in FIG. 1 as being supported on the mounting board 80.

In accordance with an important feature of the invention, a switch 110, shown in FIG. 9, is further incorporated in series with the leads 103 and 104 and the anti-parallel connected devices 81 and 100 (which could be replaced by a triac-type device) and the switch 110 is operated by the potentiometer 52. Thus, when the potentiometer 52 is operated to an end position such that the control circuit 101 substantially cuts off the conduction of devices 81 and 100, the switch 110 can be operated to an open position, thereby to completely open the circuit between leads 103 and 104.

To this end, and as shown in FIGS. 1, 7 and 8, the switch 110 of FIG. 9 is formed of a flexible beryllium copper strip 120 which has one end thereof riveted to panel 80, as by the rivet 121. A U-shaped section 122 is formed in strip 120 which extends through an opening 123 in board 80 and the other end of strip 120 is terminated in a contact 124. Contact 124 is a movable contact which cooperates with a stationary contact 125 carried directly on the panel 80.

The protrusion 122 of the flexible spring contact arm 120 is further arranged to cooperate with the end of arm 60 which is moved with slider 51. Thus, when the slider 51 moves to some given or end position in the motion of slider 51, the bottom of cam member 60 will engage the top of extension 122 in FIG. 7 to flex the arm 120 downwardly, thereby to open the contact between contacts 124 and 125. This will then fully isolate the electrical circuit of FIG. 9 through the opening of the schematically illustrated switch 110. The entire switch and control mechanism which is mounted on the rear of plate 30 is then covered with an insulation housing 127 (FIG. 7) of a conventional type, which is suitably mounted on plate 30.

The switch structure is operated from the slider 23 in FIGS. 1 and 5 to 8. The slider 23 is provided with upwardly turned end sections 130 and 131 which engage the inner surface of cover plate 30 and slide between the end surface of plate 30 and the upper surface of fins 15 to 18. An operating handle 132 is provided in a central region of slider 23 and extends through the elongated opening 140 of cover plate 30. Note that the slotted opening 140 of cover plate 30 can be the conventional slot of the usual rocker-type switch conventionally used in home lighting circuits. If desired, however, a special wall plate having a slotted opening, particularly designed for use with a relatively wide slider, can be provided with the dimmer of the invention.

The slider 23 is then held in position for longitudinally sliding relative to the wall plate 30 by suitable grooves which may connect the wall plate 30 to the heat sink 10. The member 51, extending from the potentiometer, is then received in a suitable opening 150 (FIGS. 5 and 6) in the rear surface of the slider 23 so that longitudinal motion of the slider 23 will affect adjustment of the potentiometer 52.

It should now be noted that many variations of the above-noted structure could be made while still coming within the scope of the present invention. For example, the use of the finned heat sink arrangement could be replaced by a more conventional metallic plate having, for example, only two spaced guide extensions for the reception of the slider 23. It will be further noted that any suitable mechanical connection can be provided for the longitudinally moving member which causes lighting adjustment and subsequent operation of the switch contacts 124 and 125 of the switch 110 of FIG. 9 such that the switch opens when the slider reaches a given end position.

The heat sink 10 of the preceding figures may take several different forms while still coming within the concept of the present invention. Thus, the heat sink 10 may take the form shown in FIGS. 10, 11 and 19 for the heat sink 200. Thus, the heat sink 200 has a plurality of fins extending outwardly from one surface of a main conductive body with four circular openings 201 to 204 (FIG. 10) being used as the main mounting openings for mounting the heat sink in a suitable wall box. Further openings 205 and 206 are provided in FIG. 10 for the reception of mounting means which enables the connection of a switch housing to the bottom surface (in FIG. 11) of the heat sink 200, while further openings 207 and 208 allow the connection of a potentiometer such as the potentiometer 52 of FIG. 1 to the heat sink 200 of FIGS. 10 and 11. An elongated slot 209 is then provided for reception of the elongated operating member (member 51 in FIG. 1) of the controlled potentiometer. Note that in FIG. 10 the opening 209 is laterally displaced from the center line of the heat sink 200 so that it is disposed between the short fin elements 210 and 211. It will further be noted that the fin 211 is positioned on the center line of the heat sink 200. Obviously, the potentiometer slider shaft will be suitably fixed off the center of the heat sink 200 so that it will properly extend through slot 209.

The heat sink plate 200 is further provided with break-off notches 220 and 221 shown in FIG. 11, where these break-offs are similar to the notch 45 shown in FIG. 4. Moreover, the fins of FIG. 11 contain two elongated fins 222 and 223 which are equally spaced from the opposite sides of plate 200 and are formed at their opposing interiors with hook-shaped sections 224 and 225 respectively.

The hook-shaped section 225 is shown in greater detail in FIG. 12 and it is seen that the section provides a lower surface 226 which will be seen hereinafter to receive one side of the top surface of a slider member. Note further that the hook-shaped sections 224 and 225 in FIG. 11 face one another and are formed on the first of the fins removed from those short section fins which define a support surface for the slider to be later described.

FIGS. 13 and 14 show a slider structure intended to cooperate with the heat sink 200 of FIGS. 10 and 11. The slider 230 of FIGS. 13 and 14 has the general shape of the slider 23 of FIGS. 5 and 6 and consists of a rectangular elongated member having an operating handle 231 and having an opening 232 for reception of the end of the operating member of the sliding potentiometer to be operated by the slider 230. Note that the opening 232 could also be an elongated opening extending parallel to handle 231. Note in FIG. 13 that the opening 232 is off the center axis of the slider 230 so that it can align with and slide along the length of slot 209 in FIGS. 10 and 11.

The slider 230 may be of any desired material which will have a certain spring-type flexibility in thin sections for purposes to be described hereinafter. Moreover, the slider material should be capable of presenting a decorative appearance since the slider is visible at the switch surface. Such slider can be made of high-heat resistant styrene, nylon or the like.

If desired, the front surface of slider 230 may contain integrally raised circular sections 230a, 230b and 230c which, when exposed through the window of a covering escutcheon, will visually and tactily determine the intensity setting of the control device of the invention.

In accordance with one aspect of the invention, the slider of FIGS. 13 and 14 has slotted sections 233 to 236 at its four corners to define flexible prong-type members having upwardly beaded heads 237 to 240 respectively. It will thus be apparent that the prong members having heads 237 to 240 will have spring-type characteristics which enable these sections to flex perpendicular to the plane of slider 230.

Thus, as best shown in FIG. 19, the slider is mounted atop two of the short fin sections of heat sink 200, including short fin sections 210 and 210a, with the bottom of slider 230 resting on the top of these short fin elements. By causing the slider to rest on only two of these fins or one fin, if desired, the frictional force on the slider is decreased. The width of slider 230 is approximately equal to the width between the major side surfaces of fins 220 and 223, where the hook elements 224 and 225 of fins 222 and 223 respectively project beyond the planes of these major side surfaces.

Accordingly, the beaded prong ends 237 to 240 of the slider 230 will be captured beneath hook sections 224 and 225. More specifically, beaded heads 237 and 239 will be pressed against the bottom of hook 224, while the beaded heads 238 and 240 will be pressed against the bottom surface 226 of hook element 225.

Note in FIG. 19 that the beaded head sections are depressed out of their normal unstressed condition shown in FIG. 14 so that some biasing pressure is provided to hold the slider 230 in position, and against accidental displacement. Thus, the slider 230 will remain in a given position until a certain positive force is applied to move the slider to a new position.

It will be noted that FIG. 19 also shows the potentiometer operating member 51 extending from slider 230 to the potentiometer and switch mechanism housing 250.

In accordance with a further feature of the invention, a novel cover plate or escutcheon is provided, as shown in FIGS. 15 to 18 in place of the cover plate 30 of FIGS. 7 and 8. Note that in FIGS. 7 and 8 the cover plate 30 was used in part to hold the slider 23 in position. In the embodiment of FIGS. 10 to 19, the function of holding the slider in position is independently performed by means of the opposing notch sections 224 and 225, which latch over the side edges of the slider 230. Thus, the cover plate need no longer serve this support function, although it would be apparent to those skilled in the art that this function may continue to be served by the escutcheon to be hereinafter described.

Referring now to FIGS. 15 to 18, the novel cover plate of the invention is shown as plate 260 and consists of a generally flat sheet of material which can present an attractive appearance, yet being sturdy and of insulation characteristics. Suitable materials are a high-heat resistant styrene, nylon and the like.

The escutcheon 260 contains a rectangular opening 261 through which the handle 231 of slider 230 projects, as shown in FIG. 19. In order to secure the escutcheon 260 to the heat sink 200, a plurality of integral connecting tabs are formed upon the escutcheon. Thus, six tabs 262 to 267 are provided integral with escutcheon 260 and project from the rear surface thereof.

FIG. 18 shows one of these tabs 262 in detail, and it can be seen that the tab 262 has an outwardly projecting latching face 263. That is to say, the tab 262 has a hook shape which hooks toward the outer or closest side edge of escutcheon 260. Similarly, tabs 263 and 264 will hook outwardly and to the left in FIG. 15, while the tabs 265 to 267 hook outwardly and to the right in FIG. 15. The hook-shaped surfaces of tabs 262 to 267 then cooperate with inwardly formed latching surfaces shown in FIG. 11 as latching surfaces 270 and 271 on fins 272 and 273 respectively.

Thus, as can be understood from FIG. 19, the escutcheon 260 can be fitted onto the heat sink 200 simply by pressing escutcheon 260 downwardly so that the tabs 262, 263 and 264 latch under projection 270, while tabs 265, 266 and 267 latch under projection 271.

A further feature of the novel escutcheon of FIGS. 15 to 18 lies in the provision of break-off notches for the cover plate edges. Thus, as seen in FIGS. 15, 16, 18 and 19, the escutcheon 260 contains break-off notches 280 and 281, which are weakened sections permitting an installer to snap off one or both side sections of the cover plate in coordination with the snapping off of heat sink sections from the heat sink 200. That is to say, break-off notches 280 and 281 of the cover plate 260 are coordinated in position relative to the break-off notches 220 and 221 in the heat sink 200. It will be apparent that this same coordination between break-off position notches would be carried through regardless of the size of the plate 200. Thus, if the plate 200 were double the width of the plate shown in the illustrative drawings, the cover plate would be a similarly larger width with all breakoffs being provided at the same width positions. It will be noted in FIG. 19 that the sides of escutcheon 260 generally overlap the sides of the end fins of the heat sink 200. The length of the escutcheon 260, however, will be slightly longer than the length of the heat sink so that a certain amount of misalignment between the heat sink and the escutcheon can be accommodated when the heat sink is not mounted exactly properly within the wall box.

FIG. 19 shows a further feature of the present invention of the provision of an elongated strip 290 connected to the slider operating member 51 and covering the opening 209. Thus, strip 290 may be an elongated strip of copper having a length equal to the length of slot 209 plus the distance traversed by the slider member 51. Therefore, regardless of the position of slider 51, the member 290 will have sufficient length always to cover the slot 209. The elongated member 290 may be provided with a central openig having inwardly pressed finger elements such that the member 290 may be pressed over rod 51 with the finger elements pressing into the sides of the rod 51 thereby holding strip 290 in place.

The provision of the elongated member 290 assures against the escape of flame or the like from the interior of the switch body 250, which might otherwise be exposed through the opening slot 209. Note that by placing the elongated member 290 in the bottom of the region between fins 210 and 211, that the movement of the member 290 will not interfere with any other components of the unit.

A further embodiment of the conductive mounting plate for mounting the switch is shown in FIG. 20 as the flat metallic plate 300. This plate will then take the place generally of the mounting plate 10 of FIG. 1 and of the mounting plate 200 of FIG. 10. Note that the mounting plate 300 of FIG. 20 will have the previously described four mounting openings 301 to 304 and will further have similar mounting openings 305 to 306 for the mounting of the switch member of the bottom surface of the plate of FIG. 20. The plate will further have an elongated opening 307 for receiving an elongated potentiometer operating shaft which is to be linearly operated, actuated by a suitable slider which may take the form of the slider 23 of FIG. 1.

In order to guide the slider on the plate 300, the plate 300 may have raised central sections 308 and 309 which would receive and guide the sides of a slider disposed between them. A suitable cover plate or escutcheon may then be further provided in any desired manner to cover the slider and plate of FIG. 20.

Although this invention has been described with respect to its preferred embodiments, it should be understood that many variations and modifications will now be obvious to those skilled in the art, and it is preferred, therefore, that the scope of the invention be limited not by the specific disclosure herein but only by the appending claims.

Claims

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

1. A voltage control device comprising, in combination:

a support plate having a front and rear surface;

controllably conductive means for connection in series with an electrical load and having a control electrode; said controllably conductive means mounted relative to said support plate;

control circuit means connected to said controllably conductive means for controlling the conduction of said controllably conductive means in order to control the output voltage to said load;

and an adjustable resistor constituting a component of said control circuit means; said adjustable resistor having a linearly movable control element; adjustment of said linearly movable control element causing the change in the output voltage to said load; said adjustable resistor being mounted relative to said support plate;

said support plate having a straight, elongated slot therethrough; said linearly movable element of said adjustable resistor extending through said elongated slot and being operable from a position adjacent said front surface of said support plate;

said support plate being of conductive material; and wherein said controllably conductive means, said control circuit means, and said adjustable resistor are each supported from said support plate, and are disposed on said rear surface of said plate.

2. The device as set forth in claim 1 which further includes disconnect switch means connected in series with said controllably conductive means and an operating member connected to said disconnect switch means; said operating member being movable between first and second positions for operating said disconnect switch means between an engaged position and disengaged position, respectively; and an extension member extending from said linearly movable element and movable to engage said operating member of said switch means when said linearly movable element reaches a given position, thereby to operate said operating member from its said first position to its said second position; said disconnect switch means, operating member and extension member each mounted adjacent said rear surface of said support plate.

3. The device as set forth in claim 2 which includes an operating slider means disposed adjacent said front surface of said support plate and connected to said linearly movable element extending through said elongated slot in said plate.

4. The device as set forth in claim 3 which includes a wall plate cover for covering said support plate; said wall plate cover secured to said support plate and having an elongated opening therein for exposing said operating slider means.

5. The device as set forth in claim 2 which includes an insulation housing for enclosing, with a portion of said support plate, said controllably conductive means, said control circuit means, said adjustable resistor and said disconnect switch means.

6. The device as set forth in claim 5 which further includes a pair of terminal leads connected in series with said controllably conductive means and said disconnect switch means and extending externally of said insulation housing.

7. The device as set forth in claim 6 wherein said front surface of said support plate contains at least first and second laterally spaced, parallel projections for receiving said operating slider means therebetween and for guiding the motion thereof.

8. The device as set forth in claim 7 wherein said front surface of said support plate contains a plurality of parallel, spaced heat fins; a centrally disposed group of said heat fins terminating in a generally common plane, at least one of said centrally disposed group slidingly supporting the adjacent surface of said operating slider means, and at least one pair of outwardly disposed heat fins extending beyond said common plane serving as lateral guides for guiding the motion of said operating slider means.

9. The device as set forth in claim 6 wherein said front surface of said support plate contains a plurality of parallel, spaced heat fins; a centrally disposed group of said heat fins terminating in a generally common plane, at least one of said centrally disposed group slidingly supporting the adjacent surface of said operating slider means, and at least one pair of outwardly disposed heat fins extending beyond said common plane serving as lateral guides for guiding the motion of said operating slider means.

10. The device as set forth in claim 1 wherein said support plate is adapted to be mounted in a wall box, and wherein said load is a lighting circuit load, and wherein said device is a light dimmer.

11. The device as set forth in claim 1 which includes an insulation housing for enclosing, with a portion of said conductive support plate, said controllably conductive means, said control circuit means, and said adjustable resistor.

12. The device as set forth in claim 11 which further includes a pair of terminal leads connected in series with said controllably conductive means and extending externally of said insulation housing.

13. The device as set forth in claim 11 which includes an opening slider means disposed adjacent said front surface of said conductive support plate and connected to said linearly movable element extending through said elongated slot in said plate.

14. The device as set forth in claim 13 which includes a wall plate cover for covering said conductive support plate; said wall plate cover secured to said conductive support plate and having an elongated opening therein for exposing said operating slider means.

15. An electrical control device adapted for mounting in a wall box, comprising, in combination:

a support plate having a front and rear surface, a straight elongated slot extending through said support plate;

electrical current control means secured to said support plate at said rear surface thereof;

an operating shaft connected to said electrical control means and extending through said elongated slot and movable along said elongated slot to operate said electrical control means;

an operating slider means disposed adjacent said front surface of said support plate and connected to said operating shaft;

a plurality of parallel spaced fins extending outwardly from said front surface of said support plate including a centrally disposed group of fins terminating in a generally common plate spaced from and parallel to said front surface, at least one of said centrally disposed group slidingly supporting said operating slider means, and further including at least a pair of fins on opposite sides of said centrally disposed group and extending beyond said common plane, and defining lateral guides for receiving the sides of said operating slider means and for guiding the motion thereof.

16. The control device of claim 15 wherein said pair of fins contain hook-shaped protrusions on the ends thereof which hook over the sides of said operating slider means to press said operating slider means against said group of fins.

17. The control device of claim 16 wherein said operating slider means includes spring-type means connected to the sides thereof which press against said hook-shaped protrusions of said pair of fins.

18. The control device of claim 15 wherein said plurality of spaced fins further include a second pair of fins outwardly displaced on either side of said pair of fins; and an escutcheon plate for covering the said front surface of said support plate; said escutcheon plate having an opening therethrough for permitting access to said operating slider means; the surface of said escutcheon plate which faces said support plate having snap-type connector means extending therefrom; said snap-type connector means being connectable to at least one of said plurality of fins for receiving said escutcheon plate in place relative to said support plate.

19. The control device of claim 18 wherein said second pair of fins have snap connection means disposed generally at the outer ends thereof for receiving said snap-type connector means of said escutcheon plate.

20. The control device of claim 18 wherein said escutcheon plate has first and second parallel elongated weakened sections defining break-off sections, extending along the length thereof and removed by the same distance from the sides of said escutcheon plate, and wherein said support plate has first and second parallel elongated weakened sections defining break-off sections, extending parallel to said plurality of fins, and at the base of said fins, and disposed adjacent said first and second weakened sections in said escutcheon plate.

21. The electrical control device of claim 18 wherein the surface of said slider means includes position indicia thereon; said position indicia consisting of a plurality of raised dots spaced from one another in a direction parallel to the direction of movement of said slider means.

22. The electrical control device of claim 18 wherein said escutcheon plate has a length longer than the length of said support plate whereby said escutcheon plate completely covers said support plate over a range of length of relative displacement between said escutcheon plate and said support plate.

23. The control device of claim 15 which includes elongated strip means connected to said operating shaft and movable between adjacent fins of said plurality of fins and substantially covering said elongated slot, regardless of the position of said operating shaft along the length of said slot.

24. The control device of claim 15 which further includes an escutcheon plate for covering the said front surface of said support plate; said escutcheon plate having connector means extending from one surface thereof; said plurality of spaced fins including at least one pair of opposed fins having serrations in their opposing surfaces; said connector means extending from said one surface of said escutcheon plate being force-fit between said serrations in said opposing fin surfaces.

25. The control device of claim 15 which further includes an escutcheon plate for covering the said front surface of said support plate; said escutcheon plate having screws extending from one surface thereof; and said plurality of spaced fins including at least one pair of opposed fins having serrations in their opposing surfaces and adapted to receive said screws.

26. The device as set forth in claim 1 which includes elongated strip means connected to said linearly movable element; said elongated strip means disposed adjacent said front surface of said support plate and covering said elongated slot regardless of the adjustment position of said linearly movable element.