US2890355A

US2890355A - Magnetic display motor

Info

Publication number: US2890355A
Application number: US485419A
Authority: US
Inventors: Gustave A Berthel
Original assignee: Individual
Current assignee: Individual
Priority date: 1955-02-01
Filing date: 1955-02-01
Publication date: 1959-06-09
Anticipated expiration: 1976-06-09

Description

June 9,1959 e. A. BERTHEL MAGNETIC DISPLAY MOTOR I5 Sheets-Sheet 1 Filed Feb. 1, 1955 INVENTOR. GUSTAVE BERTHEL Y Y b i mo- ATT'YS June 9, 1959' G. A. BERTHEL MAGNETIC DISPLAY MOTOR 3 Sheets-Sheet 2 Filed Feb. 1. 1955 INVENTOR:

GUSTAVE A. BERTHEL '..BY

4 I ATT'YS June 9, 1959 G. A. BERTHEL 2,890,355

MAGNETIC DISPLAY MOTOR Filed Feb. 1, 1955 5 Sheets-Sheet 3 INVENTOR. GUSTAVE A. BERTHEL ATT'YS United States Patent MAGNETIC DISPLAY MOTOR Gustave A. Berthel, Park Ridge, Ill.

Application February 1, 1955, Serial No. 485,419

1 Claim. (Cl. 310-39) The invention relates to electro-magnetically actuated display motors for the operation of animated display devices, such as are commonly used for advertising purposes, and particularly to improvements in such motors whereby their construction and operation is materially simplified and whereby the operating efllciency is increased.

Several different types of such electro-magnetic display motors, having a magnetically driven oscillating part, are known in the art and to a certain extent have been successfully employed commercially. One particular handicap with respect to these display motors, however, is that because they are generally intended for use in locations where connection to a continuous power source is not feasible and therefore must be driven by battery power, the power required by their operation drains the battery in a relatively short time, so that the battery must be frequently renewed or replaced. For the sake of operational economy the devices are usually designed for operation by an ordinary single-cell flashlight battery and thus the battery life is inherently limited so that any unnecessary loss of power due to structural characteristics of the motor serves only to decrease the already limited battery life. It is therefore a particular object of this invention to improve the construction of battery operated electromagnetically actuated oscillating motors so as to decrease the power loss due to friction and the inertia of any moving parts, thus increasing the operational life of the battery and providing a display motor which will operate continuously for a considerably greater length of time than the previous devices have been able to accomplish.

Other particular objects of this invention are to provide a simplified magnetic display motor construction wherein the mass of the moving parts is more efliciently arranged so as to minimize driving power required for the motor operation; to provide an oscillating electromagnetic dis play motor in which frictional losses will be minimized; to provide a simplified magnetic display motor construction which will be cheaper to manufacture; to provide such a device having an improved arrangement for regulating the motor speed or frequency of oscillation; and to provide an improved electro-magnetioally actuated oscillating display motor having a sturdy construction, and which is less likely to become damaged or out of adjustment under ordinary conditions of usage and handling.

A specific embodiment of this invention is shown in the accompanying drawings, in which:

Figure 1 is a perspective view of the improved electromagnetic display motor construction showing the device from the mounting side of the same.

Fig. 2 is a perspective view of the same showing the rear or battery mounting side.

Fig. 3 is a fragmentary perspective view showing the construction and arrangement of the oscillating member for operating the driven shaft of the display motor.

Fig. 4 is a diagrammatic view showing the electrical pircuit of the improved display motor.

2,890,355 Patented June 9, 1959 Fig. 5 is an elevational side view of the improved display motor.

Fig. 6 is a sectional view of the same as taken on line 6-6 of Fig. 5, and

Fig. 7 is a similar sectional view, but showing the oscillating member in its swinging positions.

In the form shown in the drawings the improved magnetic display motor comprises a box-like frame or chassis, having a front wall 1, a rear wall 2, and top and bottom walls 3 and 4 respectively, the sides of the chassis being entirely open. The bottom wall 4 of the chassis projects outwardly beyond the rear wall 2 to provide a platform 5 which serves as a base or support for a battery 6 (see Fig. 5) which supplies the motive power for the device, and the front wall 1, which in the form shown is integral with the bottom wall 4, is provided with a pair of vertically spaced, downwardly projecting, mounting fingers or lugs 7, by means of which the display motor may be mounted on or attached to the stationary body portion of the display which the motor is to animate.

The top wall 3 of the chassis is preferably a U-shaped member having downwardly projecting front and rear leg members 8, which overlap and are attached to the front and rear walls 2 of the chassis by means of centrally located hollow rivets, 9 and 10, which serve as bearings for the driven shaft 11 of the motor, the shaft 11 extending from front to rear through the walls of the motor chassis adjacent its upper end. The rear Wall 2 of the chassis is of dielectric material and, in addition to its function as the rear Wall of the chassis, serves as a support for an upper battery terminal 12, and an intermittent contact arm 13, which will be later described.

The improved display motor construction comprises essentially a solenoid having a fixed or stationary core and a movable coil suitably mounted to oscillate back and forth along a path substantially coincident with the axis of the core. In the construction of the present invention, the movable coil is mounted as a pendulum adapted to swing along an arcuate path, and the fixed core is a permanent magnet disposed to extend longitudinally of the arcuate path, the end of the magnet constituting north and south poles, respectively. Thus whenever the coil is energized by a flow of current therethrough, in the ap propriate direction and at the proper time in relation to its movement over the magnet, a magnetic reaction is created between the coil and the core which provides an impulse to the pendulous swing of the coil in the direction of its movement along the arcuate path. This prin- .ciple for actuation of a magnetic display motor is not new, and will be readily understood by those skilled in this art. The arrangement of the parts, however, in the present invention is believed to provide new and unexpected results which greatly enhance the operational efiiciency of the motor, and in this respect the mounting of the coil as a swinging pendulum with respect to a fixed permanent magnet core is believed to be new and of considerable advantage.

As shown in the drawings the coil 14 is suspended directly from the driven motor shaft 11 by means of a single arm 15 which is fixed to and projects radially from the shaft 11. The arm 15 is attached to the shaft by means of a bracket member 16, which extends lengthwise along the shaft and is secured thereto as by the integral inner and outer turned

cars

17 and 18, respectively, which are clamped tightly around the shaft 11. As shown, the arm 15 has a pair of diverging branch members 19, at its lower end, which terminate in turned up hook portions 20 adapted to engage in suitable openings from near the upper edges of a pair of coil supporting end plates 21, made of dielectric material, between which the coil 14 is fixedly mounted. As shown the coil 14 is wound on a tubular core 22, also made of a suitable dielectric material, the ends of which are suitably fastened to the dielectric end plates 21. Thus the coil 14 is a hollow cylindrical member having an axial passage therethrough, and is a relatively concentrated mass mounted to swing as a pendulum about the axis of the motor shaft 11.

The shaft 11 extends through and is journaled in the hollow rivet members 9 and It at the upper end of the motor chassis or frame, and the coil hangs downwardly from the shaft 11 for swinging movement in a vertical plane between the forward and rear walls 1 and 2 of the chassis. In this arrangement the endmost ears 18 of the bracket 16 seiwe as guides to engage the inner ends of the hollow rivet bearings 9 and 10 and thus limit movement of the coil and shaft assembly between the front and rear walls of the chassis and in the direction of the shaft axis.

The permanent magnet core 23 of the improved motor is suspended from the top wall 3 of the motor chassis, by means of

lateral arms

24 and 25, which extend outwardly from each side of the chassis in a plane normal to the axis of the motor shaft 11 and then converge arcuately and downwardly along a circular path concentric with the axis of the shaft 11 and coincident with path of the center of the coil 14 as it swings about the shaft axis. The length of the

arms

24 and 25 is preferably such as to subtend an are somewhat greater than the maximum extent of pendulous swinging of the coil 14, so as to be well beyond the adjacent end of the coil when the coil is at its maximum height along the path of its swinging movement. For example, a clear arcuate path of from 150 to 160 appears to be suificient.

As shown in the drawings, the permanent magnet 23 is a cylindrical body, about one-third again as long as the length of the coil 14, which body is attached endwise to the arcuate portions 26 of the

arms

24 and 25. The permanent magnet 23 is secured fast on the arm portions 26, and the

arms

24 and 25, which may be integral portions of a single member, are secured to the top Wall 3 of the motor chassis in any suitable manner as by the hollow rivets 27. In the construction shown the permanent magnet 23 is precisely centered in the motor chassis, and with respect to a vertical plane through the axis of the motor shaft 11. Thus the permanent magnet is held in fixed position at the center of the are along which the center of the coil travels in its pendulous oscillating movement.

It will be understood that with devices of the nature of the present invention, actuation of the motor is r brought about by momentary energization of the coil 14, so that opposite ends of the coil acquire the characteristics of north and south poles respectively, to cause the coil to react magnetically with the north and south poles of the permanent magnet 23. Thus with the coil wound so that the end adjacent the north pole of the permanent magnet has north pole characteristics, and the end of the coil adjacent the south pole of the permanent magnet has south pole characteristics, the like poles of the two elements will tend to repel each other, at certain relative positions of the elements, and the unlike poles will tend to attract each other, thereby imparting a driving impulse to the swinging coil. Such energization of the coil however must be momentary only and should occur in properly time relation with respect to the position of the coil in the field of the permanent magnet during the back and forth swinging movement of the coil. Therefore, suitable momentary contact means must be provided in the motor structure for energization of the coil at the right time and for the right period to obtain maximum efficiency of the electro-magnetic influences which tend to produce relative movement between the coil and the magnet.

As shown in the drawings, the fixed contact 13 projects inwardly, parallel with the shaft 11, from a bracket member 28 mounted on the inside of the chassis wall 2, adjacent its upper end and immediately below the motor shaft 11, which contact extends into the path of a spring finger 29 carried by and movable with the arm 15 which supports the swinging coil 14. The fixed contact bracket 28 is attached to the chassis wall 2 by one of the rivets 30 by which the upper battery terminal 12 is mounted and thus the contact 13 is directly connected electrically with the battery terminal 12. The spring finger contact 29 is mounted parallel with the coil supporting arm 15 on a dielectric plate 31 which is secured to and extends from the coil supporting arm toward the rear wall 2 of the chassis.

The plate 31 is preferably located near the lower end of the arm 15 so that the spring finger, in extending upwardly therefrom to engage the fixed contact 13, will have sufficient length to be freely flexible in a plane normal to the axis of the shaft 11; and the length of the spring finger contact 29 is preferably such as to only slightly overlap the fixed contact 13, when engaged therewith, so as to drag itself clear of the fixed contact as the trailing end of the coil reaches or passes the end of the permanent magnet having the opposite polarity. This relationship of the spring finger contact 29 and the fixed contact 13 is clearly shown in Figs. 3 to 7 inclusive.

As shown in Fig. 3, a felt pad 32 is threaded lengthwise onto the spring finger 29 so as to dampen any tendency of the spring finger vibrating after it has been sprung clear of the fixed contact 13 during swinging movement of the coil. This is a common expedient in devices of this nature, and will be readily understood by those skilled in the art.

As shown in Figs. 6 and 7, the contact element 13 mounted on the rearward wall 2 of the chassis projects inwardly therefrom so as to be within the path of movement of the free end of the spring finger 29, and the contact 13 is located slightly off center with respect to a vertical radius from the axis of the shaft 11, so that when the core 14 is hanging centrally and at rest the spring finger 29 will be just out of engagement with the fixed contact. The reason for this arrangement is that when the core 14 is at rest and centered on the permanent magnet 23, the electromotive force at each end of the coil and acting between the coil and the permanent magnet would be equal if the coil were energized at that position. Thus, under such circumstances there would be no movement of the coil relative to the permanent magnet if the contacts were engaged with each other, but there would be a continuous drain of current from the battery which supplies the activating energy to the motor. Thus by arranging the contacts so that they are not engaged when the coil is in center position and at rest, drain of the battery for the foregoing reason is obviated.

It will now be understood that the improved electromagnetic display motor is started in its operation by swinging the coil manually to impart a pendulous motion thereto and cause repeated momentary engagement of the spring finger 29 with the fixed contact 13 as the coil passes over the magnet. When the contacts are engaged the coil 14 will become energized with the same axial polarity as the magnet. However, the inertia of the swinging coil will carry it to a position beyond center before the full magnetic force of the coil is generated, so that the trailing end of the coil will be approaching the end of the magnet having the opposite polarity, and the magnetic forces acting on the coil will be such as to kick" the coil in the direction of its swing. The reverse of this action takes place upon the return swing of the coil and in either case the engagement of the contacts is broken substantially as the trailing end of the coil passes the end of the magnet having the opposite polarity. Thus, as long as the battery has sufiicient energy to activate the coil, the coil will continue to swing back and forth to turn the shaft 11, the pendulous movement of the coil mass being given an impulse in the direction of its swing each time it passes over the magnet.

The electrical circuit for the improved magnetic display motor is shown in Fig. 4 of the drawings, wherein it is shown that the negative side of the battery 6 is grounded and the positive side is connected to the fixed contact 13. One end of the coil 14 is connected to the finger member 29 and the opposite end of the coil is grounded so that a circuit between the battery and coil is completed whenever the

contacts

13 and 29 are engaged. In the construction of the device, the battery 6 is held with its base or negative end resting on the platform 5, projecting from the rear side of chassis, and the positive end of the battery is engaged by the terminal 12, which is preferably of resilient conductive material, to clamp the battery in place. The battery is thus grounded to the chassis. The terminal 12 leads through the dielectric rear wall 2 of the chassis to the fixed contact 13 by way of the mounting rivet 30 and the bracket member 28 and the circuit is continued through the spring finger 29 to the coil 14, one end of the coil being electrically connected to the lower end of the finger 29. The opposite end of the coil 14 is connected electrically with the adjacent support member 19 on the arm 15, and thence is grounded to the chassis by Way of the motor shaft 11. In this manner a complete electrical circuit within the motor assembly is obtained by two simple, very short connections leading from the coil winding and wholly contained between the end plates 21 by which the coil 14 is supported. It will be understood that the connections with the respective ends of the coil 14 will be such that the direction of the coil winding will produce the same polarity at the ends of the coil as the respective ends of the magnet extending coaxially through the coil.

As shown in Figs. 1, 2 and 5, the forward end of the shaft 11 which extends beyond the front wall 1 of the chassis is bent at right angles to the shaft axis, and is then turned upon itself to form a loop 33 onto which the element of the display which is to be actuated by the motor may be attached, as by means of a suitable clip. Thus as the shaft 11 is rocked back and forth on its axis by means of the swinging coil 14, the loop 33 will oscillate to the same extent so as to impart a similar motion to the element to which the loop is attached. Preferably the element mounted on the loop 33 will be balanced with respect to the coil 14, so that when the assembly is at rest, the coil 14 will be substantially centered with respect to the magnet 23, gravitationally.

In order to vary the period of oscillation of the improved display motor, a secondary pendulum having a radially adjustable weight may be mounted on the rear end of the shaft 11, as shown in Fig. 5, and such as arrangement may comprise a collar 34 mounted on the rear end of the shaft 11 and having a radially extending rodlike arm 35 on which is mounted a weight 36 which may be adjusted lengthwise of the rod 35, the weight 36 being provided with a finger tightened set screw 37 for this purpose. With this arrangement the speed of the motor may be varied within a considerable range in the same manner that the speed of a pendulum clock is adjusted. Thus by moving the weight 36 outwardly relative to the axis of the shaft 11, the pendulous movement of the motor may be made slower, or by moving the weight 36 toward the axis of the shaft 11, the speed of the motor may be increased.

The secondary pendulum 3536 may also be used as a counterbalance for the actuated element mounted on the loop 33, at the opposite end of the shaft 11, and for such cases the collar 34 is attached to the shaft 11, by means of a set screw 38, so that the collar 34 can be adjusted angularly about the axis of the shaft 11, as may be necessary to counterbalance the object mounted on the loop 33, so that when the motor is at rest the coil 14 will be held gravitationally in substantially a centered relation with respect to the magnet 23.

In the use of the improved display motor it will be understood that the motor is mounted on the back side of a stationary portion of the display by means of the hook members or lugs 7, and the forward end of the shaft 11 projects through the display so that the loop portion 33 will be on the front side of the stationary member. The movable portion of the display is then clipped or otherwise suitably mounted on the looped portion 33. A battery 6, preferably of the ordinary flashlight dry cell type, is then mounted on the rearwardly extending platform portion 5 of the motor chassis with the positive terminal of the battery engaged by the spring terminal 12 which extends rearwardly from the rear wall 2 of the chassis. The motor is started by manually turning the shaft 11 so as to impart a pendulous motion to the coil 14, after which the intermittent energization of the coil as it passes over the stationary magnet 23 will cause such a reaction between the coil and the magnet as to give a positive impulse to the coil in the direction of its swing each time that it passes the magnet 23. The magnetic impulses which tend to kick the coil in the direction of its movement, are suflicient to fully overcome the gravitational forces acting on the system and tending to stop the pendulous movement of the coil, and the motor will continue to operate until the battery 6 is exhausted or until the motor is manually stopped.

The main advantages of this invention reside in the simple construction of the improved display motor; and in the fact that by virtue of the particular arrangement of its parts less power is required for its operation and hence the operational life of the battery which drives the motor is greatly increased.

Further advantages of this invention are to be found in the construction whereby the mass of the moving parts of the motor is concentrated at the end of a single arm projecting radially from the driven shaft; in the construction and arrangement of the improved motor whereby the speed of its operation may be varied and whereby the operated load can be quickly and easily counterbalanced for the most efficient operation of the motor; and in the fact that the improved arrangement and construction of the motor assembly permits manufacture at a considerably lower cost than prior devices of a like nature.

Although but one specific embodiment of this invention has been herein shown and described, it will be understood that details of the construction shown may be altered or omitted without departing from the spirit of this invention as defined by the following claim.

I claim:

An oscillating magnetic motor comprising a frame having spaced vertical front and rear walls and open sides, a shaft journaled horizontally on the upper portion of said frame and normal to said walls, a radial bracket member fixed to said shaft and extending lengthwise thereof between said walls for limiting axial movement of said shaft, a cylindrical coil suspended pendulously from said bracket on a rigid arm fixed thereto and projecting radially from the shaft, said coil being swingable in a plane normal to the axis of said shaft to rock said shaft and having an open ended axial passage extending in the direction of its swing movement, an elongate permanent magnet disposed in axial alignment with said coil and extending along the swing path thereof for a distance less than one-half the total swing arc of the coil, means fixed on said frame and extending along the swing path of said coil for supporting said magnet in fixed position relative to said frame and substantially midway in the swing arc of the coil, a resiliently flexible contact member mounted by one end on said arm and having a free end extending parallel therewith in spaced relation axially of said shaft, said contact member being insulated from said arm and electrically connected to one end of the coil winding and the other end of the winding being electrically connected to said arm, a fixed contact mounted on one of the frame walls and projecting there- References Cited in the file of this patent UNITED STATES PATENTS Ritchie Oct. 21, 1873 Favre-Bulle et a1 Oct. 24, 1922 Bates Mar. 1, 1938 Wengel June 3, 1952