US2183062A - Alternating-current directcurrent clock - Google Patents

Description

Dec. 12,' 1939. F. CONRAD ALTERNATING-CURRENT- DIRECT-CURRENT CLOCK Filed July 27, 1932 d m w 4 I l l I I I l I h J\ F2 7 WITNESSES ATTORN EY Patented Dec. 12, 1939 2,183,062

UNITED STATES PATENT OFFICE ALTEBNATlNG-CUBBENT DIRECT- CURRENT CLOCK Frank Conrad, Wllldnsburg, Pa., asaignor to Westinghouse Electric in Manufacturing Com- P y, East Pittsburgh, Pa., a corporation of Pennsylvania Application July :1, 1m. serial No. 025,141

1: Claims. (c1. ss-zo) My invention is directed to improvements in alternationsof most commercial altematingclocks or oscillating mechanisms which can be current systems, whether Gil-cycle, 25-cycle, or actuated either on alternating current or on direct 50-cycle.

current, and it has particular relation to a clock A further object of my invention is to equip the 6 which, in its preferred form of construction. is electromagnetic driving-mechanism for the tim- 6 capable of synchronizing itself with the alternaing shaft with a special type of contact make-andtions of the source of current therefor when it is break mechanism which is particularly advanbeing energized from an alternating-current tageous in this mechanism. source. With the foregoing and other objects inview, 10 My present invention is a modification of a drymy invention consists of the apparatus, systems 10 battery clock which constituted the subiect-matand methods hereinafter described and claimed, ter of a copending application, Serial No. 178,061, and illustrated in the accompanying drawing, filed March 17, 1927, Patent No. 1,911,062, granted wherein: May 23, 1933, for Electric clocks, an important Figure 1 is a front elevational view of a clock feature of which was a mechanical movement for mechanism embodying my invention, with the u converting the oscillating movement of the timing front plate removed, as indicated by the section shaft or balance-wheel shaft into uni-directional plane I--I in Fig. 2; step-by-step rotary movement, the amount of Fig. 2 1s a side elevational view on a plane lookrotary movement being unaffected by the ampliing in a direction indicated by the arrows 11-11 tude of the oscillations of the timing shaft, within in Fig. 1;

' wide limits, which is necessary in a clock mecha- Fig. 3 is an enlarged sectional view, on the plane nism. III-III in Fig. 2, through the gear mechanism for One of the objects of my present invention is to converting oscillatory movement into rotary provide a dual electric supply system for a clock of movement;

this same general type, said dual supply system Fig. 4 is a top plan view of the parts shown in 25 comprisinga transformer for reducing the voltage Fig. 3, looking in the direction of the arrows of a commercial alternating-current house-circuit IV-IV in Fig. 2; to a very low voltage which is rectified by means Fig. 5 contains a sectional view through the of a small contact rectifier or its equivalent, and a oscillating shaft, showing the contact mechanism small flashlight battery, for standby operation and the relative positions of the stator and rotor 30 when the power is off, said battery being conpoles, on the plane V--V in Fig. 2, with a dianected in series with an electromagnetic switch on grammatic representation of the electromagnet the transformer for cutting the battery in or out coil and other parts of the electric circuit, and according as the transformer is .deenergized or Figs. 6 and '7 are curve'diagrams showing, re-

energized, the contact rectifier preventing the spectively, the uni-directional voltage half-waves battery from discharging into the transformer which are supplied by the transformer and rectiwinding when the battery is in operation. It will fier, and the current which is admitted into the be understood, of course, that either source of electromagnet coil by the contact mechanism on electric current may be utilized separate from the the timing shaft. 40 other. My timing mechanism comprises a timing shaft 40 Another object of my present invention is to I carrying a balance wheel 2 having a plurality of provide a different type of hairspring mechanism pole members I and 4 which cooperate with the or mounting whereby the hairspring, as distinstationary pole piece 5 of an electromagnet 8 guished from the universal practice in clocks and which is mounted on the front plate I of the 46 watches, is deliberately designed to have a very mechanism,' said front plate being preferably poor regulation, so that it will increase its speed of magnetizable, and of such large area that it provibration when its amplitude increases and convides a fairly good return path, through the air, trarily. The use of a timing shaft having such a 1J1 the magnetic flux from the electromagnet pole hairspring, in connection with an electromagnetic which is attached to the plate.

50 operating mechanism which is energized by half- The oscillating movement of the timing shaftis 50 wave impulses received from an alternating-curtransmitted to the clock gear train 8 through a rent source. and a rectifier, results in a clock mechanical movement whichis particularly shown which is capable of adjusting its speed,.within and described in my above-mentioned copending certain l mits, to the frequency of the impressed application. As more particularly shown in the t5 alternations, so as to take advantage of the timed enlarged views of Figs. 3 and 4 of the accompany- 56 ing drawing, this mechanism comprises righthand and left-hand worm-gear elements III and I I carried by the timing shaft I and cooperating with a toothed wheel I 2 lying in a plane which includes the timing shaft, with the teeth of the toothed wheel extending up close to the timing shaft so as to be engaged by the worm-gear elements I0 and I I. As set .forth in my copending application, each of the worm-gear elements I0 and II has a short inclined-plane surface I3 and an annularly extending surface I4 which is normal to the timing shaft. Each inclined-plane surface has a limited circumferential extent of n degrees, and

each annular normal surface has a circumferen.-'

tial extent of approximately (3602n) Each of. the two inclined-plane surfaces I3 has an axial extent greater than a half tooth-pitch of the toothed Wheel I2, so that, when the oscillating timing shaft I moves in the direction of the arrow I5 in Fig. 4, through any distance or amplitude greater than n degrees, and up to its maximum possible extent of about (360-11 from its mid-position I3, the inclined-plane surface I3 of the worm-gear element I0 will push thetoothed wheel one-half tooth-pitch to the left. When the oscillating timing shaft returns again to its mid-position I6, the inclined surface element I3 moves in between two of the teeth of the toothed wheel I2, and the toothed wheel I2 remains stationary, without any retrograde movement. When the oscillating shaft reaches its mid-position, in this movement which is now contrary to the arrow I5 in Fig. 4, or about this time, the other inclined-plane surface I3 which is carried by the second worm-gear element II engages a tooth of the toothed wheel to push it another half. tooth-pitch in the same direction as before, thus converting the oscillatory movement of the timing shaft into a step-by-step rotational movement which is unaffected by theamplitude of the timing shaft within the wide limits of 11. degrees and about (360-n) in either direction from the mid-position of the shaft.

In the foregoing description of themechanical movement for converting oscillatory into rotational movement, it was stated that the toothed wheel I2 had no retrograde movement. It is quite essential, in this type of mechanism, particularly when applied to a clock or other precision instrument, to guard positively against any retrograde movement of the toothed wheel I2, which might result either from the resiliency or backlash of the time gear train 8 or from the backward movement of the hands of the clock in the process of setting the same. To this end, as explained in my copending application, I provide the shaft ll of the toothed wheel I2 with a worm gear or other non-reversible gear mechanism l8, as shown more particularly in Figs. 1 and 2, utilizing this worm gear It to drive the clock gear train 8.

The energy for maintaining the oscillations of the timing shaft is provided by means of the above-described electromagnet 6 which receives very brief current-impulses, at predetermined points in the oscillation, under the control of a contact make-and-break mechanism comprising a small pin 20 carried by the timing shaft close to the timing shaft and a contact-making leafspring 2|, the far end of which is stationarily supported on an insulating post 22. The contactmaking leaf-spring 2I is biased to lie in the plane of the timing shaft and extends towards the shaft at right angles thereto so that its near end 24 is engaged by the pin 20 slightly before the 33 or equivalent rectifying device.

oscillating timing shaft reaches its mid-position in either direction of travel. Thereafter, as the timing shaft continues to move, the pin 20 carries the contact-making leaf-spring 2| to one side, untilthe timing shaft has traveled a predetermined distance less than n degrees beyond its mid-posltion,, at which time the pin passes around from under the end of the leaf-spring and permits the latter to snap back into its normal position, breaking the contact.

Reference to Figs. 1 and 5 will show that the contact-making leaf-spring is associated with two shorter leaf- springs 25 and 26, one'on either side of it.- said shorter leaf-springs being supported in the same stationary support and serving the function of. damping the vibrations of the contact-making leaf-spring 2I when the latter snaps back into its normal position after breaking contact with the timing-shaft pin 20. The friction between the surfaces of the contact-making leaf-spring 2I and the two shorter leafsprings 25 and 2B effectually damps any oscillations.

The contact members 20-2I are connected in series with the electromagnet coil 6, so that the latter is supplied with current which begins to flow just before the timing shaft reaches its midposltion. When the shaft is in its mid-position, the two poles 3 and 4 of the balance wheel are at substantially equal distances from the stationary pole 5 of the electromagnet. The current remains in the electromagnet until the timing shaft has moved well past its mid-position, so that the main effect of the electromagnetic flux is developed when one of the moving poles 3 or 4 is much closer to the stationary pole 5 than the other moving pole is, so that the closer moving pole will be attracted to the stationary pole, affording the necessary impulse to maintain the oscillation. This effect of the electromagnet is increased, also, by the time-lag or slowness with which the flux builds up therein and also the slowness with which the flux dies down therein, this latter function being increased by virtue of a high-resistance shunt 28, of perhaps 500 or 1000 ohms, which is connected across the electromagnet coil 6 for the purpose of reducing sparking at the contact members 2Il2I. In Figs. 1 and 2 this high-resistance shunt 28 is shown in a common commercial form consisting of a core member around which a very fine high-resistance wire is wound, the same being covered with insulation so that it looks like an ordinary insulated wire.

I preferably provide a dual current supply for the electromagnet 6, although it is to be distinctly understood that I may use either one of the current sources by itself. As shown more particularly in Fig. 5, I provide a very small transformer 30 having a high-voltage winding 3| which is adapted to be energized from an ordinary timedfrequency commercial alternating-current line. such as IIll-volt house current of either (SO-cycle frequency or 25-cycle frequency. The transformer 30 also has a low-voltage winding 32 which supplies a very low Voltage to the electromagnet coil 6, through a copper-oxide rectifier This rectifier. as shown. comprises an oxide-coated copper plate 34 having a cuprous oxide coating C1120 on one side, the oxide-coated surface being in contact with a dissimilar plate 36 of other material such as lead. Such a rectifier has the property of permitting substantial current-flow only in the direction from the oxide coating into the copper, so

. air-gap 31 which is by-passed by means of a magnetizable armature, 38 which is mounted on a spring 38, so asto be biased to a position away from the core of the transformer 30. The armature 38 carries, at its end, a spring contact member 40 which engagesa stationary contact 4| when the transformer is deenergized. When the transformer is energized, the armature II is attracted to the core so as to bridge the air-gap 31, and

the contact 40- is broken. The contact 40- is connected in series with a small flashlight battery or single dry-cell 42 which is likewise connected to supply current to the electromagnet 8 through the timing-shaft contact make-andbreak device 20-2i, whenever the electromagnetic switch 40'-4l is closed. It will be noted that the polarity of the copper-oxide rectifier II is such as to prevent the discharge of the drybattery 42 through the low-voltage winding 32 of the transformer.

In the particular design shown in the drawing, the timing shaft l makes 150 complete oscillations per minute. so that the half-period of oscillation of the timing shaft, or time'between successive makings of the contact' mechanism 202l, 1S"1/5 of a second, which is exactly 12 complete cycles on a 60-cycle system or 5 complete cycles on a 25-cycle system. In some cases, a suflicient synchronising action may be obtained when said half-period of oscillation is equal to an odd number of half-cycles of said commercialfrequency system, particularly when the duration of each contact is less than a quarter-cycle, so that every alternate contact is made during a half-cycle when the current-flow is substantially blocked by the rectifier.

The effect of the rectifier I3 is to cut oil alternate half-waves of the impressed alternating voltage, one of said cut-off half-waves being indicated by dotted lines 44 in Fig. 6. The result is a series of uni-directional half-waves of voltage which are supplied by the transformer-rectifier aggregate. Fig. 6 shows these voltage half-waves for a 60-cycle supply system. I v

Every twelfth wave, on a BO-cycle system, or, in general, at equal time intervals which are an exact multiple of the period of the alternatingcurrent system, the timing-shaft contact makeand-break mechanism 20-2| makes a brief contact, which is held for only a short period which should be materially less'than a full cycle of the alternating-current supply. system and is preferably of the order of cycle of the alternating-current supply circuit or even less. A contact period of nearly one-half cycle of the 60- cycle supply system is indicated at AB in Fig. 7 although I believe that my contact period is really somewhat less than this.

The balance-wheel shaft i is caused to oscillate by means of a hairspring or balance-wheel spring 48 which is deliberately designed not'to keep too good time. This may be accomplished oy providing a wide space between the regulator prongs 41 and 48, as distinguished from the usual construction in which these prongs closely embrace the hairspring. The result is that when the balance-wheel shaft I is operating through a wide amplitude, say 200 on either side of its midposition, the clock is running too fast, and when the balance-wheel shaft l is oscillating through a small amplitude, say 60 on either side of its mid-position, the clock is operating too slow,

whereas at some intermediate amplitude, such as 150 on either side of the mid-position, the

clock is keeping correct time. degrees would be 60.

The result of the foregoing construction is that, when the clock is operating on the rectified alternating-current supply, if there should be a momentary decrease in the frequency of the supply source, the contact periods AB would fall largely or altogether within the alternatingcurrent half-cycles in which no current is supplied by the rectifier, so that the amplitude of oscillation of the timing shaft would decrease, bringing down with it the frequency of oscillation, until the first part of each contact period AB falls within the latter part of a half-cycle of the current which is supplied by the rectifier, as indicated at 50 in Fig. 7 which shows the current supplied to the electromagnet coil under such circumstances. The amplitude of oscillation, and hence the frequency of oscillation, will continue to decrease until a suilicient amount of the half-cycle of current is included in the contact period AB to maintain the precise amplitude of oscillation necessary to cause the clock to run at the correct time, orin accordance with the frequency of the commercial alternating-current system to which the clock is connected. My clock is thus enabled to operate synchronously with the supply system and to follow variations in the supply frequency, up to departures of a small amount, such for example as a'quarte'r of one per cent or one-half of one per cent, more or less than the nominal frequency of 60-cycles, 25- cycles or whatever the frequency is. If the frequency of the supply circuit should depart from its nominal frequency by so great an amount that the clock cannot follow the departure, the clock will continue to run at its own rate, deriving energy impulses, for maintaining the oscillation of the timing shaft, from the alternating-current souce, but not keeping in step with the alternating-current source.

The amount of power required by my clock is extremely small. It is so small that, when the clock is operated during off-power periods from a small flashlight battery, the life of the battery is practically its shelf life. The design is such that when the battery is supplying current to the clock, the average strength of the battery current, during the useful life of the battery, is about sufficient to make the amplitude of oscillation of the timing shaft such that the clock keeps correct time, so that in the off-power periods, when the clock is operating oil of the battery, or when the clock is operating solely from the battery, without the use of an alternatingcurrent supply source, the clock will keep, on the average, substantially correct time.

While I have illustrated my invention in a preferred form of ombodiment and have mentioned figures and proportions of an actual construction, it will be understood that my invention is not altogether limited to these details and that many modifications and changes may be made by those skilled in the art within the spirit of my invention. I desire, therefore, that the appended claims shall be accorded the widest construction consistent with their language and the prior art.

I claim as my invention:

1. An electric timing mechanismadapted to be In this case, n

synchronously operated on a commercial alternating-current timed-frequency power system, comprising a balance wheel having a plurality of spaced magnetizable pole pieces, a balance-wheel shaft therefor mounted for oscillatory movement in both directions from a mid-position of the balance wheel, a balance-wheel spring therefor,

said balance-wheel spring being of a type which causes the oscillating balance-wheel system to materially increase its rate of oscillation when its amplitude increases, contact make-and-break means operated by said balance-wheel system for periodically making a contact for a brief period of time, relative to the total oscillating period, beginning each period of contact slightly before the balance wheel reaches its aforesaid inid-posi tion in either direction of travel, an electromagnetic means having a stationary pole member which is disposed substantially symmetrically with respect to two of said balance-wheel pole pieces when the balance wheel is in its aforesaid midposition, but which is approached by the one or the other of said two balance-wheel pole pieces when the balance wheel moves from its aforesaid mid-position, according to the direction of movement, and a pair of conductors and rectifler means serially associated in operative rela-- tion thereto for supplying a series of discontinuous half-waves of a predetermined potential to said contact make-and-break means and to said electromagnetic means. I

2. An electric timing mechanism adapted to be synchronously operated on a commercial alternating-current time-frequency power system,

comprising a balance wheel having a plurality of spaced magnetizable pole pieces, a balance-wheel shaft therefor mounted for oscillatory movement in both directions from a mldpositlon of the balance wheel, a balance-wheel spring therefor, said balance-wheel spring being of a type which causes the oscillating balance-wheel system to materia ly increase its rate of oscillation when its amplitude increases and conversely, contact makeand-break means operated by said balance-wheel system for periodically making a contact for a brief period of time, relative to the total oscillating period, beginning each period of contact slightly before the balance wheel reaches its aforesaid mid-position in either direction of travel, the duration of said contact being materially less than one cycle of said alternating current, an electromagnetic means having a stationary pole member which is disposed substantially symmetrically with respect to two of said balance-wheel pole pieces when the balance wheel is in its aforesaid mid-position, but which is approached by the one or the other of said two balance-wheel pole pieces when the balance wheel moves from its aforesaid mid-position, according to the direction of movement, a voltage-reducing means, and rectifier means associated with the low-voltage terminals of said voltage-reducing means for supplying a series of discontinuous half-waves of a predetermined potential to said contact makeand-break means and to said electromagnetic means.

3. An electric timing mechanism adapted to be synchronously operated on a commercial alterhating-current time-frequency power system, comprising a balance wheel having a plurality of spaced magnetizable pole pieces, a balance-wheel shaft therefor mounted for oscillatory movement n both directions from a mid-position of the balance wheel, a balance-wheel spring therefor, said balance-wheel spring being of a type which causes the oscillating balance-wheel system to materially increase its rate of oscillation when its amplitude increases and conversely, contact make-and-break means operated by said balancewheel system for periodically making a contact for a' brief period of time, relative to the total oscillating period, beginning each period of com tact slightly before the balance wheel reaches its aforesaid mid-position in either direction of travel, an electromagnetic means having a stationary pole member which is disposed substantially symmetrically with respect to two of said balancewheel pole pieces when the balance wheel is in its aforesaid mid-position, but which is approached by the one or the other of said two balance-wheel pole pieces when the balance wheel moves from its aforesaid mid-position, according to the direction of movement, an alternating-current voltage-reducing means, rectifier means permanent y associated with the low-voltage terminals of said voltage-reducing means and with said contact make-and-break. means and said electromagnetic means for normally supplying a series of discontinuous half-waves of a predetermined potential to said contact make-and-break means and to said electromagnetic means, a battery, and an electromagnetically operated switch for disconnecting the battery when the voltagereducing means is energized and for connecting the battery to said contact make-andbreak means and tosaid electromagnetic means when the voltage-reducing means is deenergized, the direction of conduction of said rectifier means being such as to substantially keep the battery current out of the voltage-reducing means when the battery is connected in circuit. 7

4. An electric timing mechanism adapted to be operated on either alternating current or direct current, comprising a balance wheel of a type having poor regulation, a balance-wheel shaft therefor, a balance-wheel spring therefor, contact make-and-break means operated by said balance-wheel system for periodically making a contact for a brief period of time, relative to the total oscillating period, at a predetermined point in the oscillation of the balance wheel, electromagnetic means associated with said contact make-and-break means for periodically supplying a driving-impulse to said balance wheel, a pair of alternating-current conductors and a battery in said timing mechanism, rectifier means permanently serially associated with said alternating-current conductors and with said contact make-and-break means and said electromagnetic means for normally supplying a series of discontinucus half-waves of a predetermined potential to said contact make-and-break means and to said electromagnetic means, and an electromagnetically operated switch for closing its switchcontacts when said alternating-current conductors are deener'gized, said switch-contacts being in series with said battery for supplying direct current to said contact make-and-break means and to said electromagnetic means, the direction of conduction of said rectifier means being such as to substantially keep the battery current out of the alternating-current conductors when the battery is connected in circuit.

5. An electric timing mechanism adapted to be synchronously operated on a commercial alternating-current timed-frequency power system, comprising a balance wheel, a balance-wheel shaft therefor, a balance-wheel spring therefor, said balance-wheel spring being of a type which causes the oscillating balance-wheel system to materially increase its rate of oscillation when its amplitude increases and conversely, the half period of oscillation of the oscillating shaft being approximately equal to a whole number of cycles of the commercial frequency for which the timing mechanism is designed, contact make-andbreak means operated by said balance-wheel system for periodically making a contact for a brief period of time, relative to the total oscillating period, at a predetermined point in the oscillation of the balance-wheel, electromagnetic means associated with said contact make-and-break means for periodically supplying a drivingimpulse to said balance wheel, a pair of conductors and rectifier means permanently serially associated in operative relation thereto and permanently serially associated in operative relation to said contact make-and-break means and said electromagnetic means for normally supplying a series of discontinuous half-waves of a predetermined potential to said contact make-and-break means and to said electromagnetic means, a stand-by source of power for operating said timing means when alternatingcurrent power is off or disconnected, and said stand-by source comprising a battery, an electromagnetically operated switch for closing its switch-contacts when said alternating-current conductors are deenergized, said switch-contacts being in series with said battery for supply ing direct current to said contact make-andbreak means and to said electromagnetic means,

the direction of conduction of said rectifier means tion of the oscillating shaft being approximately equal to a whole number of cycles of the commercial frequency for which the timing mechanism is designed, contact make-and-break means operated by said balance-wheel system for periodically making a contact for a brief period of time, relative to the total oscillating period, he-

ginning each period of contact slightly before the balance wheel reaches its aforesaid midposition in either direction of travel, an electromagnetic means having a stationary pole member which is disposed substantially symmetrically with respect to two of said balance-wheel pole pieces when the balance-wheel is in its aforesaid mid-position, but which is approached by the one or the other of said two balance-wheel pole pieces when the balance wheel moves from its aforesaid mid-position, according to the direction of movement, a step-down transformer, rectifier means permanentlyassociated withthelow-voltagesideof said transformer and withsaid contactmake-andbreak means and said electromagnetic means for normally supplying a series of discontinuous halfwaves of a predetermined potential to said contact make-and-break means and to said electromagnetic means, a battery, and an electromagnetically operated switch for disconnecting the battery when the transformer is energized and for connecting the battery to said contact makeand-break means and to said electromagnetic means when the transformer is deenergized, the direction of conduction of said rectifier means being such as to substantially keep the battery current out of the transformer when the battery is connected in circuit.

7. A time mechanism comprising an oscillating timing shaft, electromagnetic driving-mechanism for causing said timing shaft to oscillate periodically through more than n and less than (360n) in each direction from its mid-position, where n is less than 180, and a contact make-and-break device for controlling said electromagnetic driving-mechanism, said contact make-and-break device comprising a small pin carried by the timing shaft close to the timing shaft and a contact-making leaf-spring supported stationarily at its far end and extending toward the timing shaft so that the near end of the spring is engaged by said pin slightly before the timing shaft reaches its aforesaid mid-positon and breaks its contact before the timing shaft has traveled n beyond its aforesaid midposition, in either direction of travel, said contact-making spring being biased to return to a central position with respect to the timi 1g shaft, and a shorter leaf-spring on each side of, and in substantially continuous frictional contact with, said contact-making leaf-spring for damping the vibrations'of the latter.

8. A time mechanism comprising an oscillating timing shaft, electromagnetic driving-mechanism for causing said timing shaft to oscillate periodically through more than n" and less than (360-11) in each direction from its mid-position, where n is less than 180, means for causing the,

oscillation-rate of said timing shaft to materially increase with an increase in amplitude within said limits of 11 and (360-n) from said mid-position, a contact make-and-break device for controlling said electromagnetic drivingmechanism, a pair of alternating-current conductors and a battery in said timing mechanism, rectifier means permanently serially associated -\with said alternating-current conductors and with said contact make-and-break device and said electromagnetic driving-mechanism for normally supplying a series of discontinuous halfwaves of a predetermined potential to said contact make-and-break device and to said electromagnetic driving-mechanisrn, and an electro 9.' A time mechanism comprising'an oscillating timing shaft, electromagnetic driving-mechanism for causing said timing shaft tooscillate periodically through more than n" and less than (360-n) in each direction from. its mid-position, where n is less than 180, means for causing the oscillation-rate of said timing shaft to materially increase with an increase in amplitude within said limits of n' and (360-12) from said mid-position, a contact make-and-break device for controlling said electromagnetic driving-mechanism, an alternating-current voltagereducing means, rectifier means permanently associated with the low-voltage terminals of said voltage-reducing means and with said contact make-and-break device driving-mechanism for normally supplying a seand electromagnetic ries of discontinuous half-waves of a predetermined potential to said contact make-and-breal: device and to said electromagnetic driving-mech anism, a battery, and an electromagnetically operated switchfor disconnecting the battery when the voltage-reducing means is energized and for connecting the battery to said contact makeand-break means and to said electromagnetic driving-mechanism when the voltage-reducing means is deenergized, the average amplitude of oscillation produced by said voltage=reducing means and rectifier means being about the same as that produced by said battery.

10. .A time mechanism comprising an oscillating timing shaft of a type having poor regulation, electromagnetic driving-mechanism for causing said timing shaft to oscillate periodically through more than 11 and less than (360-n) in each direction from its mid-position, where n is less than 180, a contact make-and 'break device for controlling said electromagnetic drivingmechanism, an alternating-current voltage-reducing means, rectifier means permanently associated with the low-voltage terminals of said voltage-reducing means and with said contact make-and-break device and said electromagnetic driving-mechanism for normally supplying a series of discontinuous half-waves of a predetermined potential to said contact make-and-break device and to said electromagnetic driving-mechanism, a'battery, and an electromagnetically op erated switch for disconnecting the battery when the voltage-reducing means is energized and,for connecting the battery to said contact makeand-break means and to said electromagnetic driving-mechanism when the voltage-reducing means is deenergized.

11. A time mechanism comprising an oscillating timing shaft, electromagnetic driving-mechanism for causing said timing shaft to oscillate periodically through more than 11 and less than (360-n) in each direction from its mid-position, where n is less than 180, means for causing the oscillation-rate of said timing shaft to materially increase with an increase in amplitude within said limits of n and (360n) from said mid-position, a contact make-and-break device for controlling said electromagnetic drivingmechanism, and a pair of alternating-current supply-conductors and rectifier means associated in operative relation thereto for supplying a series of discontinuous half-waves of a predetermined potential to said contact make-andbreak means and to said electromagnetic driving-mechanism, said contact make-and-break device comprising a small pin carried by the timing shaft close to the timing shaft and a contact-making leaf-spring supported stationarily at its far end and extending toward the timing shaft so that the near end of the spring is engaged by said pin slightly before the timing shaft reaches its aforesaid mid-positionand breaks its contact before the timing shaft has traveled n beyond its aforesaid mid-position in either direction of travel, said contact-making spring being biased to return to a central position with respect to the timing shaft, and a shorter leafspring on each side of, and in substantially continuous frictional contact with, said contactmaking leaf-spring for dumping the vibrations of the latter.

12. An electric timing mechanism adapted to be synchronously operated on a commercial alterhating-current timed-frequency power system comprising an oscillating timing shaft, electromagnetic driving-mechanism for causing said timing shaft to oscillate periodically throughmore than n" and less than (36Q-n) in each direction from its mid-position, where n is less than 180, means for causing the oscillation-rate of said timing shaft to materially increase with an increase in amplitude within said limits of n and (BSD-n) from said mid-position, a contact make-and-break device operated by said timing shaft for periodically making a contact slightly before the timing shaft reaches its mid-position and breaking said contact before the timing shaft has traveled n beyond its mid-position, in either direction of travel, said contact make-and-break device being connected to control said electromagnetic driving-mechanism, the angular veloc ity of said oscillating timing shaft near its midposition and the angle of duration of one of said contacts being such that the time of duration of one of said contacts is materially less than one cycle of the commercial frequency for which said timing mechanism is designed, and a pair of alternating-current supply conductors and electromagnetic driving-mechanism for causing said timing shaft to oscillate periodically, a contact make-and-break device operated by said timing shaft for controlling said electromagnetic driving-mechanism, a pair of alternating-current conductors and a battery in said timing mechanism, rectifier means permanently serially associated with said alternating-current conductors and with said contact make-and-break device and said electromagnetic driving-mechanism for normally supplying a series of discontinuous half-waves of a predetermined potential to said contact make-and-break device and to said electromagnetic driving-mechanism, and an electromagnetically operated switch for closing its switch-contacts when said alternating-current conductors are deenergized, said switch-contacts being in series with said battery for supplying direct current to said contact make-and-break means and to said electromagnetic driving-mechanism.

FRANK CONRAD.

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