US 2246373 A
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Description (OCR text may contain errors)
June 17, 1941. E, 5. LODGE 2,246,373
ELECTRIC SWITCH Filed Jan. 50, 1939 tacts. In either event, the switches-operate stiilly prevent the ball from likewise nioving transverseto' the ball.
Patented June l'v, 1941 L UNlri-:D 4STATES PATENT OFFICE ELECTRIC SWITCH Application January so, 1939, serial No. 253,638
This invention relates to electric switches, and more particularly to those in which an electric bridging. member is reciprocable across' a'plurality of laterally spaced electric contacts or terminals. 5y
One of the greatest dliliculties with switches of this character is that they are undependable in operation because the bridging members sometimes bind in their actuators, This causes the switch either to fail to operate or to make un- 10 satisfactory electric contact which burns the conor jerkily.
It is among the objects of this invention to provide a slide switch which operates smoothly 15 at all times, which is dependable in operation, which is simple and inexpensive in construction, and in which thebridging member does not bind but always makes good contact with the terminals regardless of inaccurate positioning of 20 f the terminals. f
In accordance with this invention a plurality 3 of terminals are mounted in laterally spaced re` lation in a substantially straight line. An actuating member is disposed adiacent the terminals 2" `where it is slidable lengthwise of the common line in which the terminals lie. Means is provided, such as a housing, for limiting the longi-sf tudinal movement of the actuator. .The actuator n is provided with a recess for receiving a bridging "0 member which it carries back and forth across the terminals. The bridging member consists of a metal ball which is biased into fcontact with two adjacent terminals at a time by means oi' a coil spring 'compressed between tl'ieball and the 3 inner end of the actuator recess. The recess is enlarged to permit the ball to move across it longltudinally of the actuator in order to compensate for inaccurate positioning of the terminals. 'Io 4o ly of thefactuator and thereby-moving away `from both terminals, the sides of the recess adjacent the sides of the actuator are in close proximity To keep the spring from working 45` g itself down around the ball and thereby wedging (ci. zoo- 16) 4 and 5 are horizontal sectionstaken on theu lines IV-IV and V-V, respectively, of Fig. 2; Referring to the drawing, a housing is provided which is shown in the general form ofu a channel; that is, it has a web or top wall I and parallel flanges or side walls 2. The top wall hs extensions `at its lends provided with openings 3 by means of which the switch is fastened in place to the desired support. Although 'this housing may be made of any suitable material, it is preferred to make it of metal and -to provide the free edges of its side walls with lugs 4 which are bent over the edges of a base member 6 to position the lattei in spaced parallel relation to the top of the husing. The' edges of this base member are pro-v vided with notches 1 (Fig. 4) u:for receiving the lugs in order to hold the' base member in predetermined position longitudinally of the housing. The base member is made of insulating material, such as a small strip of Bakelite. Mounted in this base are aplurality of one-piece terminals each .of which has a partially spherical contact portion or detent II disposed against the inner face of the base, and parallel portions projecting from the opposite sides of the detent through slots `in the base, one of these latter portions having an extension I2 adapted to be connected to a wire oflan electric circuit, and the other terminating in a lug I3 bent over the base to lock the terminal in place (Fig. 3). Lugs 4 and I3 are prevented from coming in contact with wires attached to the terminals by means of a slotted insulating strip I4 through which terminal extensions I2 project.
Disposed in the housing between its top and the base member is an actuating member which is slidable longitudinally of the base and housing. This actuator, which is preferably made of a molded insulating material, has a generally rec tangular body I6 and an integral button I1 projectinggoutwardlyi through a slot I8 in the top wall of `the housing. The opposite ends of this slot limit the longitudinal movements of the'actuator by acting as stops against which the button abuts. The side of the actuator adjacent the base is provided with a longitudinally extending channel I9 into which terminal detents IIproject, The central portion of the actuator is provided' with a `recess 2| extending into button I1 i and having its open end adjacent the terminals.
It is a feature of this invention that two adjacent terminals are bridged, in order to close an electric circuit, by a bridging metal ball v22 loosely disposed in recess 2l of the actuator by irregularities of switch manufacture.
which it is carried back and forth over the terminals. As shown in Fig. 2, the ball is biased against the terminals by means of acoil spring 23 which is compressed between it and the inner end of the recess. The spacing of the terminals and the size and described what I now consider to represent its best embodiments. However, I desire tohave it understood that, within the scope of the apof the. ball kare such that when the balll is :ln
the depression between two of the spherical detents Il it can sim ltaneously engage both of them in order to clo e an electric circuit.
A ball bridging member has the very great advantage of loose mounting without a stem projecting up into the recess to cant and bind and thereby prevents uniform contact with both terminals. It also makes the switch operate more y `easily because it tends to roll over the terminals.
The spherical detents I l are inexpensive to make and prevent the ball from touching the insulating base member 6 in which it might wear grooves and thereby cause rough operation of the switch.`
Due to inaccuracies that invariably creep into the manufacture of these switches, the terminals are not always spaced the same distance apart or the same distance to the side of the axis of recess 2| when the actuator is at either end of its path of movement. In prior switches this tended to prevent the bridging member from making proper contact with the terminals. 'Ihis objection is overcome by this invention by enlarging the recess longitudinally of the actuator so that there is considerable clearance between lthe ball and two opposite walls of the recess when the ball is centered therein. If, when actuator button I1 engages one end of slot I8, the projected axis of recess 2|. is not exactly half-way between two of the contact detents il, ball 22 will move forward or backward in the recess, as necessary, to accommodate itself to the positionpended claims, the -invention may be practiced otherwise than as specically illustrated and described.
I claim: A
l. An electric switch comprising a housing having a slot in its top, an insulating base for the housing, a plurality of terminals projecting from the inner face of the base, said terminals having spherical contact portions laterally spaced in a substantially straight; line extending longitudinally of the housing and slot, a slidable actuator disposed in the housing for movement longitudinally thereof and provided with a button projecting through said slot, the body of the actuator being provided with a recess having its open end facing the terminals, a ball loosely disposed in the recess, a coil spring compressed between the ball and the inner end of the recess for biasing the ball into bridging contact with two adjacent terminals, the ends of said slot being adapted to be engaged by said button to limit the longitudinal movement of the actuator, and said recess confining the movement of the ball longitudinally of -the base to substantially a straight line but being enlarged at the 'sides of the ball adjacent the ends of the, -slide to permit the ball to properly engage said terminals.
2. An electric switch comprising-a metal housing having a slot-in its top and having substanf tially parallel side-walls, an insulating base disposed between the free ends of the side walls,
ing of the terminals and thereby compensate for However, as shown in Fig. 5, the recess 'is not enlarged transversely of the actuator, but is provided with substantially parallel straight walls in close proxy imity to the ball s o that the ball can not move transversely of the actuator. Otherwise, if such transverse movement were permitted, the ball might move laterally out of contact with one or both of the spherical contacts.
Another feature of this invention is that spring 23 is so formed that, in spite of the clearance in the recess, it does not work or slip down around the side of the ball and thereby become i wedged between the ball and the side of the re cess in an inoperative position. Accordingly, the convolution of the spring which engages the ball is smaller than most, if not all, of the remaining convolutions so that the spring engages the ballin a circle whichv isso small that the ball can not project upV into the lower convolution far enough to be able to expand it.
According to .the provisions of the patent statutes, I have explained the principle and con-A struction of my invention and have illustrated ,saidv walls being provided with lugs overlapping the bottom of the said base, a'plurality of electric terminals having spherical contact portions projecting from the inner face of the base ina substantially straight line extending longitudinally of the housing and slot, said terminals extending through said base and projecting from its bottom, a slidable actuator disposed in the housing for movement longitudinally thereof and provided with a button projecting through said slot, the body of the actuator being `provided with a recess having its open end facing the terminals, a ball loosely disposed inthe recess, said recess confining the movement'of the ball longitudinally of the b ase to substantially a straight line but-being enlarged at the sides of the walls adjoining the ends of the slot to permit the ball to seat against two adjacent terminals, a coil spring compressed between the ball and the inner end of the recess for biasing the ball into bridging contact with two adjacent terminals, the ends of said slot being adapted to be engaged' by said button to limit the longitudinal movement of the actuator, and an insulating member provided with openings through which the outer portions of said terminals project, said member overlying said lugs.
EDMUND G. LODGE.