US2047902A - Electric switch - Google Patents

Description

July 14, 1936. I A, EWZ 2,047,902

' ELECTRIC SWITCH v 7 Original Filed April 23, 1929' A TTORNEY Patented July 14, 1936 I UNITED STATES PATENT OFFICE ELECTRIC swrrcn August D. Eitzen, Rockville Centre, N. Y., as-

signorto ,News Projection Corporation, New York, N. Y., a corporation of New York cember 8, 1934 9 Claims. (01. 200-52) My present invention relates generally to an improved electric switch and more particularly to an improved electric switch employing a conductive liquid as-the contact effecting means and the present application is a division of my Patent No. 1,944,173 dated January 23, 1934.

Among the main objects of the present invention, it is aimed to provide a construction which employs an electric motor and which resorts to the control of speed of. the motor by means of a rheostat, the present construction, however, being devoid of frictionally-made electric contacts. I have found that'by the employment of a rheostat with a. series of contacts over which a complementary contact travels and makes frictional engagement, difiiculties are encountered by virtue of the wear and tear upon the contacts, the constant exposure thereof, and the problems of sparking which arise. In accordance with my present invention, a plurality of contacts. are

are achieved by my present construction, despite the fact, as mentioned, that only a single element is subject to movement.

The stationary well which I employ is substantially U-shaped and I provide a supply of conductive liquid therein normally at a relatively low level. A set of contacts are arranged in association with the well, and the method of bringing the liquid into predetermined association with these contacts relies upon the principles of liquid displacement, a displacement member being so constructed and arranged as to enter the liquid and cause a change in level thereof, accordingly.

Another object of my invention is to provide an automatic rheostat device of the foregoing character wherein sparking is reduced to a minimum.

I accomplish this by means of a non-conductive liquid suitably associated with the conductive liquid so as to quench as quickly aspossible sparks formed.

It is still another object of the present invention to provide an improved switch which is essentially adapted for use with a stock quotation projection machine.

A general object of my invention is to provide a construction which is extremely simple, compact, inexpensive to manufacture, easy to install, and eflicient and reliable in operation.

It is still another object of the present invention to provide a rheostat which is sensitive to a minimum change in actuating force.

For the attainment of the foregoing objects and such other objects as may hereinafter appear or be pointedout, I have constructed a device embodying the feature of my invention and illustrated in the accompanying drawing wherein- Figure 1 is an enlarged elevational view, partly in section, illustrating the details of the improved switch, and showing the electrical connections diagrammatically;

Fig. 2 is a'plan view of Figure 1, all electrical leads having been omitted for the sake of clearness; and

Fig. 3 is an elevational view, mainly diagrammatic, showing a stock ticker projecting machine provided with this improvement.

. It is well known that a stock ticker, adapted to discharge marked tape, functions periodically or intermittently depending upon the variable transactions which it records. Where a tape of this character is passed. through a projecting device, so that the markings thereon may be cast upon a suitable screen or screens, it has frequently been the custom to provide a tape-pulling mechanism which draws the tape through the projecting device as long as the ticker discharges the same, and ceases to draw the tape whenever the ticker ceases to operate. With tickersv which operate at relatively great speeds, a constant transmission of tape through the projecting device at a corresponding speed, interrupted by periods of rest of the tape, is somewhat objectionable because of the strain upon the eyes of the observers. It is far preferable to draw the tape through the projecting device at varying rates of. speed conforming to the rates at which the ticker is operating so that periods of absolute rest occur only at those times when the ticker has ceased to function for a sustained period of time. I

In view of the foregoing, the present improved electric switch is particularly adapted for use with a stock quotation projection machine. In Figure 3, I have shown a stock ticker III which is adapted to discharge a marked tape l I, the latter entering andpassing through a suitable projecting device l2 and being thereupon directed toward arewinding or tape-drawing mechanism l3. Within the projecting device I2 is a source of light and other suitable mechanism for projecting a beam of light upwardly through the marked tape and through a suitable objective M or the like, thence onto a screen. The interior mechanism of the projecting device l2 has not been shown. The rewinding mechanism designated by the reference numeral IS in Figure 3 includes'an electric motor which has not been shown in this figure but which is diagrammatically represented in Figure 1 by the reference numeral l5. This motor has an armature l6 and a field Between the stock ticker Ill and the projecting device I2, I provide the apparatus hereinafter to be more fully described, and in the illustrated embodiment I have shown this apparatus attached to a side of the projecting device |2 as by means of a bracket l8. It consists of a well |9 which is substantially U-shaped in that it embodies two upwardly extending arms. As viewed in Figure 1 the left arm 20 conforms to an arcuate portion of a torus ring. The extent of this are is approximately as illustrated. The other arm of the well 2| is substantially straight, of smaller bore than the arm 20 and inclined upwardly at a slight angle (shown at approximately 30) to the horizontal. In the illustrated embodiment, the entire well is constructed of insulating material such as bakelite, hard rubber, or the like, although it will be obvious after this specification has been read that the well itself need not necessarily be of insulating material.

Mounted in association with the arm 2| so as to project into the interior of the latter are a set of electrical contacts. One contact 22 is positioned at the lower end of the arm 2| and is electrically connected as by means of a lead 23 to one side of the line or current source. The other contacts constitute a group and are all electrically connected through a rheostat or resistance 24 to the armature in which circuit, this switch element has been intercepted. More particularly, it is to be noted that the field winding I1 is arranged in parallel with the armature |6, in the case of a shunt motor. as shown in the drawing. While the field remains on the line its current does not pass through, the switch. It is of course understood that the present invention will work equally as well with a series motor or any variable speed type motor. A lead 25 leads from the armature I6 to a terminal 26 which is preferably adjustable for purposes of installation and manufacture, but which is stationary once the device has been set into operation. The terminal 26 establishes elec-' trical contact with one end of the resistance 24, and a number of leads 21 extend from spaced portions of the resistance 24 to the contacts above referred to as a group. These contacts are arranged in sequence longitudinally along the arm 2| and for illustrative purposes I will point out that the first contact 28, connected with the end of the resistance 24 opposite the terminal 26, is'positioned slightly and next above the contact 22; whereas the last contact 29, connected to the resistance 24 at the point nearest the terminal 28, is positioned at the greatest distance from the contact 22.

Within the well I provide a supply of conductive liquid such as the mercury 30, and this supply is just sufllcient in quantity so that the level thereof is normally too low to touch and submerge all of the contacts. More particularly, this level is of such a height that normally itsubmerges onlypredetermined certain of the contacts. In

the illustrated form, the level of the mercury is normally at a point where it submerges the contact 22 to establish electrical connection therewith.

Beforedescribing the other features of my invention, it will be obvious that under normal circumstances the motor will not be running for although one side of the line or current source is electrically connected with the mercury 30, through the contact 22, the other side of the armature is out of contact with the mercury 30. It will also be obvious that a rise in level of the mercury in the arm 2| will successively establish contact with the remaining contacts. That is, a rise in level will initially cause the mercury to touch and submerge the contact 28, and a continued rise will successively establish connection with the remaining contacts, until finally all the contacts, including the last contact 29, will be submerged in the mercury. As the contacts from 28 to 29 are touched by the mercury, the motor will not only start at a slow rate of speed, but will speed up gradually, the rise of mercury cutting out successive portions of the resistance 24. Similarly, when the mercury level falls, successive portions of the resistance 24 will be reinserted in the circuit of the motor and will cause a slowing of the latter.

The manner in which I cause the mercury level to rise and fall is a particular feature'of my invention. It is to be noted that the upper ends of the U-shaped well I9 are open to the atmosphere. Although I prefer to provide a cap 3| upon the outer end of the arm 2|, nevertheless it is to be noted that a small aperture 32 is provided. This exposure of the well simplifies the device and allows me to dispense entirely with the use of any gaseous pressures or the like.

Briefly, I achieve the desired rise and fall of the mercury level by a principle of displacement of liquid, a displacement member being so constructed and mounted that it is adapted to enter the mercury in the torus ring 20 of the well, thereby causing the mercury level to rise accordingly in both arms of the well. I have illustratively shown a displacement member 33 which is pivoted at 34, the axis of this pivot being coincident with the center of curvature of the torus ring previously mentioned. The member 33 carries a head 35 which is arcuate and concentric with the axis of the pivot 34. The head 35 is adapted to swing in an are within the arm 2|. In Figure 1, it has been shown out of contact with the mercury 30, but it is obvious that when the member is swung in a counterclockwise direction, as viewed in this figure, the head 35 will enter the mercury 30 and displace corresponding amounts thereof.

It is particularly to be noted that the head 35 is entirely out of contact with the walls of the well, and it is not to be confused with a plunger or piston which would necessitate a tight fit and corresponding difflculty in manufacture and operation.

Inorder toreduce the illeflects of sparking to'a minimum, it is a feature of my invention to provide a small mass of non-conductive liquid such as the oil 36 upon the level of the mercury 30 in the arm 2| This oil is unreactive both physically and electrically toward the contacts touched thereby and serves the valuable, purpose of quenchingany spark which'might be induced as the level of mercury advances or recedes. It also prevents oxidation. of the mercury.

To'render the rheostat device responsive to the operation of the ticker I0, I provide a lever 31 upon the pivot 34, this lever being provided with a finger 38 adapted to rest gravitationally upon the tape I I as the latter approaches the projecting device l2.

The operation of my apparatus will be apparent from the foregoing description. Under normal circumstances the displacement member 33 is in the position shown in Figure 1 and the motor is notoperating. As the ticker commences to discharge marked tape, the finger 38 bears down upon the latter and rests within the loop or -i'estoon'which forms between the discharge opening of the ticker l and the entrance 'opening of the projecting device l2. If the rate of discharge of the ticker I 0 is not very great, this loop or festoon will not be very deep, and the motor will operate at the slow rate of speed which corresponds to electrical contact established between the contacts 22 and 28. Should the ticker l0 speed up and commence to discharge tape at a greater rate of speed, the loop of tape will increase in depth and the lever 31 will drop to a greater extent. This will cause-the head 35 to displace a greater amount of mercury and the level 01' the latter will accordingly rise to a greaterheight, successively submerging certain additional contacts in the arm 2|. As each contact is submerged, the motor will speed up by a corresponding amount. The resistance 24 is so constructed and arranged with respect to the bores of the well and the size 01' the displacement member 33 that when the ticker l0 isdischarging tape at its maximum rate of speed, the mercury will be submerging all of the contacts in the arm 2| and the motor will operate at a correspondingly rapid rate of speed sufllcient to take care of the tape being discharged. Similarly, should the ticker thereafter operate at a slower rate of speed, the advancement of the tape will not cease entirely, but a rise of the lever 31- will lower the level of the mercury by a slight degree and the motor will thereby be caused to operate at a slightly reduced speed. Eventually, when the ticker ceases to operate entirely, the pull upon the tape will cause the lever 31 to. rise into the normal position of Figure 1, at which time electrical connection to the motor will be entirely discontinued.

The extreme simplicity of my construction will be apparent to those skilled in the art. The only moving part is the displacement member 33, andv since this is pivoted, as at 34, no difliculty whatsoever is encountered in properly mounting the same and in keeping the same properly lubricated and smoothly operating. No parts of my construction need be replaced since there is nothing to wear out. Furthermore, my construction operates entirely noiselessly and requires no attention whatsoever.

It will of course be understood that this invention is not limited to employment with pro jecting machines of the character illustrated, and it is, of course, not intended to limit this invention to the specific use herein illustrated and described.

In general, it will be obvious that changes in the details herein described and illustrated and described for the purpose of explaining the nature of this invention may be made by those skilled in the art without departing from the spirit and.

scope of the invention, as expressed in the appended claims. It is therefore intended that these details be interpreted as illustrative and not in a limiting sense.

I claim:

1. An electric switch comprising a well having two arms with an intermediate depressed portion and a pair of spaced mutually insulated contacts projecting into one of said arms, a supply of conductive liquid in the well normally at a level too low to touch both of said contacts, and a movable 5 displacement member pivotally mounted for submersion into the liquid of said other arm to raise" the level of the liquid. 3

2. An electric switch comprising a well of insulating material having two arms with an intermediate depressed portion and a pair of spaced contacts projecting into one of said arms, a supply of conductive liquid in the well normally too low to touch both of said contacts, and a movable displacement member consisting of a bent arm pivotally connected at one end with its other end positioned for movement into the liquid to raise the level of the latter.

3. An electric switch comprising a U-shaped well having two arms with an intermediate depressed portion and a'pair of spaced mutually insulated contacts projecting into one of said arms,

a supply 01' conductive liquid in the well normally at a level too low to touch both of said contacts, a fixed fulcrum outside oi. said well, and a movable displacement -member consisting of a bent arm pivotally connected at one end to said fixed fulcrum and having its free end positioned for submersion into the liquid to raise the level of the latter.

4. An electric switch comprising a U-shaped well having two arms with an intermediate de pressed portion. and a pair of spaced mutually insulated contacts projecting into one of said arms,

a supply of conductive liquid in the well normally at a level too low totouch both 01' said contacts,

a fixed fulcrum intermediate said arms, and a movable displacement member consisting of an arm pivotally connected at one end to said fulcrum and bent with its other end positioned for submersion into the liquid in the other of said arms of the well for raising the level of the liquid in both arms.

5. An electric switch comprising a U-shaped well of insulating material having two arms with 4 an intermediate depressed portion and apair 01' I spaced contacts projecting into one of said arms, a. supply of conductive liquid inthe well normally too low to touch both of said contacts, a fixed fulcrum intermediate said arms, and a movable displacement member consisting of .a bent arm with the end of one portion pivotally connected to said fulcrum and the other portion extending downwardly into said other well arm for movement into the liquid to raise the level of the latter. 6. An electric switch comprising a U-shaped well having twoarms with an intermediate depressed portion, one arm of which is a section of a toms ring, a pair of spaced mutually insulated contacts projecting into the other arm, a conductive liquid in the well normally at a level too low to touch both contacts, and a movable displacement member having an arcuate portion substantially concentric with said toms-ring and another portion pivotally mounted for movement of said arcuate portion along its longitudinal axis into said torus ring arm for raising the level of the liquid.

7. An electric switch comprising a U-shaped well one arm of which conforms to a torus ring and the other arm of which is straight and only slightly inclined to the horizontal, a set of spaced mutually insulated contacts projecting into said straight arm, a conductive liquid in the well normally at a level too low to submerge all of said contacts, a fixed fulcrum intermediate said arms, and a movable displacement member, having an arcuate portion conforming to and disposed within said torus-ring arm and another portion pivotally mounted for submersion of said arcuate portion into the liquid in said torus-ring arm for raising the level of the liquid in said straight arm.

8. An electric switch comprising a U-shaped well of insulating material, one arm of which is an arcuate portion of a toms ring and the other arm of which is straight and inclined slightly upwardly, a set 01' spaced contacts in said straight arm, a conductive liquid in the well normally at a level too low to touch all of said contacts, a fixed fulcrum disposed at the center of curvature of said torus ring arm, and a displacement member having a portion pivoted to said fulcrum and provided with an arcuate head movable within said arm when said member is pivoted, said head serving to displace said liquid by varying amounts to raise the level of the liquid accordingly.

9. An electric switch comprising a U-shaped well one arm of which conforms to a torus ring 5 and the other arm of which is straight and only slightly inclined to the horizontal, a set of spaced mutually insulated contacts projecting into said straight arm, a supply of mercury in the well normally at a level too low to touch all of said con- 10 tacts, a movable displacement member conforming to said torus ring-arm and submersible into the mercury in said arm for raising the level of the mercury in the straight arm, and a supply of oil resting on the surface oi the mercury in II said straight arm. 4

AUGUST D. EITZEN.

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