US2511217A - Foot switch - Google Patents

Description

I. L. MIX

FOOT SWITCH June 13, 1950 Filed Sept. 25, 1948 FIG.1.

IRVING L. MIX

INVENTOR 'TORNE 3* Patented June 13, 1950 UNITED STATES PATENT OFFICE FOOT SWITCH Application September 25, 1948, Serial No. 51,146

3 Claims.

The present invention relates to foot switches, and particularly to a foot switch of the portable type which is designed to relieve leg fatigue of the operator.

Foot switches are widely used to instigate the operation of different types of machines and leave both hands of the operator free to perform other operations, such as, manipulating materials to be operated on by the machine. Inasmuch as such switches are usually arranged to be operated intermittently to start and stop the machine which they control, it is usually necessary for the operator to hold his foot in an unnatural position most of the time, or when the switch is not being operated, in order to hold the weight of the foot off the switch. This results in considerable leg fatigue and leg cramps in operators using the machines for long intervals and, as a result, the efiiciency of the operator decreases as time passes, and even involuntary operation of the switch, due to leg cramps, has been known to occur.

This problem of leg fatigue, in connection with foot switch operation, has been long appreciated,

but, so far as I am aware, no design of switch has heretofore been presented which satisfactorily solves this problem without complicating the design of the switch and its parts so as to make their cost unreasonable.

The most common type of conventional foot switch is that wherein the foot is supported on a treadle which pivots about or adjacent the heel, and wherein the foot is rocked forward and back on the heel to operate and release the switch, respectively. It will be appreciated that it is an unnatural position of the foot to hold the ball thereof up while resting the foot on the floor, or other support, and it has been found that to so hold the foot for any length of time is very fatiguing. If a spring strong enough to hold the foot in this position is used in the treadle of the foot switch, then this spring must be overcome in order to operate the switch and this involves a tiring effort.

In addition, certain applications of foot switches, namely, those on photographic equipment in processing stations, introduce the problem of operating in wet places where the water, or other solutions, may be standing on the floor. Such applications necessitate a switch design which will preclude short circuits due to the admittance of moisture into the electrical connections of the switch.

One object of the present invention is to provide a portable foot switch which is so designed that when it is not being operated, an operators foot is in a natural position and is fully supported so that no strain on the leg muscles is prevalent.

Another object is to provide a foot switch of the type described wherein the switch is operated and released by rocking the foot from sideto-side, and the foot is also fully supported in its switch-operating position.

A further object is to provide a foot switch of the type set forth which is simple and inexpensive in construction and one which can be used in reasonably wet places without danger of shortcircuit.

The novel features that I consider characteristic of my invention are set forth with particularity in th appended claims. The invention itself, however, both as to its construction and method of operation, together with additional objects and advantages thereof, will best be understood from the following description when read in connection with the accompanying drawings, in which:

Fig. 1 is a top plan view of a foot switch constructed in accordance with a preferred embodiment of the present invention;

Fig. 2 is a longitudinal vertical section taken substantially on line 2--2 of Fig. 1;

Fig. 3 is a front elevational view of said foot switch; and

Fig. is a schematic view showing how the foot switch is operated and released by the rocking action of the foot and how the foot is fully supported at all times.

Like reference characters refer to corresponding parts throughout the drawings.

Referring now to the drawings, a foot switch constructed in accordance with a preferred embodiment of the present invention is shown as comprising an elongated base member ID which is wedge-shaped and includes a horizontal bottom surface l! and an inclined top surface l2. The base member It is preferably a cast element, although other means of fabrication may be and is provided with a large recess 13 and a switch chamber i l at its forward end. The recess 53 is provided to lighten the structure and chamber M is provided to house a conven tional normally open switch such as that commonly known to the trade as a Micro Switch, as will be described hereinafter. By virtue of the presence of recess [3, the bottom surface ll consists of two flat areas extending completely across the base member at the front and back thereof and the bottom of the walls of the recess I3 extending lengthwise of the base member. The forward and rear flat areas are each provided with a pad l5 of non-skid material, i. e., ribbed rubber, to support the base member on the floor and prevent it from slipping therealong. If, for any reason, it is desired to fasten the foot switch to a supporting surface, a pair of countersunk holes [5 are provided in the top surface through which bolts, or screws, may pass.

Mounted in a recess in the lower end of the top surface I2 is a heel pad I! which, as shown, may be made of ribbed rubber to prevent slipping. At the forward end of the top surface and to one side of the center line thereof, there extends above the top surface the plunger ill of a conventional switch IQ of the type above referred to. This switch may be one of the single-acting or doubleacting type, but, in most instances, I have found it preferable to have it one of the single-acting type wherein the plunger is depressed and held depressed to close the switch, and is released to allow the switch to open. The switch I9 is inserted into the chamber I4 through an opening in the wall at the front of the base member and is held in assembled relation therein by a nut 2! extending through an opening in the top surface in encircling relation with the plunger l8 and engaging a threaded shank 22 on the switch. A conical-shaped cup 23 may be placed on top of the top surface in covering relation with the nut 2| and encircling the plunger IE to keep dust and other foreign matter out of the switch chamber. If the base member is metal, as is preferred, the switch chamber [4 may be lined wholly, or partially, with a sheet of insulating material 24 to insulate the switch contacts and lead wires thereto from the base member.

The opening 2!! is closed by a metal cover 25 backed up by a gasket 26 to provide a liquid-tight seal for the switch chamber; said cover being held on by screws 27. The lead cable 28 of the switch has a grommet 29 adjacent its lower end which extends through an opening 30 in the cup. This opening 3!] is smaller than the outside diameter of the grommet so that the edges thereof extend into a groove 3| around the grommet to prevent relative movement between the switchattached end of the cable and the foot switch, should the assembly be picked up by, or dragged by, the cable.

On the front end of the top surface l2 and to one side of the switch plunger I8, there is disposed a foot rest 32 for the right side of the ball of the foot, looking down on Fig. l, and particularly shown in Fig. 4. As clearly shown in Fig. 4, this foot rest 32 is on the opposite side of the longitudinal center line of the base member, as is switch plunger l8, so that when the foot is placed on the top surface of the base member,

the right side of the ball thereof engages the foot rest 32 and the left side of the ball of the foot is disposed above the plunger Ill. The extreme outer end of the rest is slightly further removed from the top surface l2 than is the top of the plunger I8 in its normal position, so that if the foot is supported normally flatwise on the heelpad l1, and the rest 32, the plunger [8 is not engaged; see the full line position of the foot in Fig. 4. To operate the switch it is only necessary for the operator to rock his foot toward the left on foot-rest 32 and the left side of the foot is lowered to depress the plunger I8 and operate the switch; see dotted line position of foot in Fig. 4. The top of the foot-rest 32 is preferably inclined downwardly toward plunger l8, as clearly shown 4 in Fig. 4, so that when the foot is rocked to operate the switch, the ball of the foot is substantially supported by the rest 32 and the plunger N3 of the switch does not have to support the weight of the foot.

From the above description it is believed that one skilled in the art, or one having occasion to use foot switches of this type,- will appreciate that a foot-switch construction, in accordance with the present invention, is a decided improvement over the prior art in that it eliminates, or greatly reduces, the possibility of leg fatigue encountered by users of foot switches of conventional design. With the present construction, the foot is completely supported at all times, so that no muscular effort is required to support the foot in an unnatural position at any time. This is true not only in the normal inoperative position of the switch, but also in the closed position of the switch. Furthermore, the fact that the foot is fully supported by rests, exclusive of the switch-operating plunger when in a switch-closing position, means that the switch mechanism, primarily the plunger actuating structure thereof, need not be specifically constructed to withstand the weight of the foot-a force which a conventional Micro Switch is not normally constructed to withstand. With the present design of switch, the only muscular effort required is that of moving the foot from side-to-side, and does not involve an eifort to hold the foot in either one of its two positions.

It will be obvious that the present design of switch makes for a relatively simple and inexpensive assembly, notwithstanding the fact that it is rugged and light enough to be readily moved from place to place. The switch and exposed electrical contacts associated therewith are suitably encased in a liquid-tight housing so that although the switch cannot be operated completely submerged in water, it can be expected to operate satisfactorily in a reasonable depth of liquid, namely, a depth which will not come up to the opening through which the grommet on the lead cable extends.

Although I have shown and described certain specific embodiments of my invention, I am aware that many modifications thereof are possible. My invention, therefore, is not to be restricted to the precise details of construction shown and described, but is intended to cover all modifications coming within the scope of the appended claims.

Having thus described my invention, what I claim as new is:

1. A foot switch comprising an elongated base member having a bottom surface adapted to rest on the floor, a top surface adapted to support an operators foot, a heel rest adjacent one end of said top surface, an electrical switch of the pushbutton type mounted adjacent the forward end of said base member, and to one side of the longitudinal center line thereof, the plunger of said switch extending through said top surface to be engaged by one side of the ball portion of the operators foot for depression and actuation of the switch, and a rest member for the ball portion of the foot fixed on said top surface adjacent the front end of the base member and to one side of the plunger of said switch, said rest member having a portion lying in a plane disposed slightly above the plane occupied by the top of said plunger in its normal poistion, whereby when the operators foot is supported naturally on the heel rest and said rest member, the

plunger will not be engaged by the ball of the foot, but by rocking the foot sideways on said rest member, said push button can be depressed to operate the switch.

2. A foot switch according to claim 1 characterized by the fact that said rest member is elongated in a direction transversely of the base member, and its top surface is inclined downwardly toward said switch member, whereby when the foot is rocked to a switch-operating position, the ball portion thereof is supported over a substantial area by the top of said rest member and the switch plunger is not called upon to support the weight of the foot. I

3. A foot switch according to claim 1 characterized by the fact that the forward end of said base member is provided with a chamber integral with the base member in which the 6 switch proper is mounted, and including an opening in one wall thereof to allow assembly of the switch in said chamber, a cable electrically connected to said switch, and means for covering said opening and holding that portion of said cable in the chamber against movement relative to said base member.

IRVING L. MIX.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 15 Number Name Date 1,478,701 Diehl Dec. 25, 1923 1,545,908 Long July 14, 1925 1,641,099 Schuster et al Aug. 30, 1927

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