US3059411A - Motion controlling and time indicating means - Google Patents

Description

Oct. 23, 1962 E. o. scHwElTzER, JR 3,059,411

MOTION CONTROLLNG AND TIME INDICATING MEANS www.

2 Shasta-SkaaiI l QQ@ wh Filed Jan. 8, 1959 Oct. 23, 1962 E. o. scHwElTzER, .JR 3,059,411

MOTION CONTROLLING AND TIME INDICATING MEANS Filed Jan. 8, 1959 2 Sheets-Sheet 2 /RPH Z CQ /07 O REPHoDz/CE O HEHD United States Patent 3,059,411 MOTION CON I ROLLING ANNSD TIME INDICATING MEA Edmund O. Schweitzer, Jr., 1002 Dundee Road, 5

Northbrook, lll. Filed Jan. 8, 1959, Ser. No. 785,682V 8 Claims. (Cl. 58-Z4) This invention relates, generally, to electric circuit means and it has particular relation to motion controlling and time indicating means. It constitutes an irnprovement over the inventions disclosed in my copending applications Serial No. 576,564, led April 6, 1956, now Patent No. 3,004,381, issued October 17, 1961, Serial No. 594,322, led June 27, 1956, and Serial No. 708,187, tiled January 10, 1958, now Patent No. 3,005,134, issued `October 17, 1961. Y

Among the objects of this invention are: To provide for moving a second member to represent a variable through the movement of a rst member `which represents another variable; to provide for engaging the second member by the iirst member regardless of the previous position of the second member; to provide for electrically operating the minute and hour hands of a clock and for automatically operating the same to indicate the correct time regardless of the time indicated by the clock at the instant of energization; to advance the minute hand at a uniform speed and to periodically advance its rotation to advance the hour hand; to reverse the minute hand through a complete revolution after it has been advanced; to accomplish these operations by shifting the phase of one alternating current with respect to the phase of another alternating current bearing a iixed relation to the frequency of the one alternating current; to record the wave form of the resulting alternating current on a tape and to control the operation of the clock hands thereby; and to record the wave form along two tracks in opposite directions along a tape and by reversing the tape obtaining continuous control of the operation of the clock hands.

Other objects of this invention will, in part, be obvious and in part appear hereinafter.

This invention is disclosed in the embodiment thereof shown in the accompanying drawings and it comprises the yfeatures of construction, combination of elements and arrangement of parts that will be exemplified in the construction hereinafter set forth.

For a more complete understanding of the nature and scope of this invention reference can be had to the following description, taken together with the accompanying drawings, in which:

FIGURE 1 illustrates diagrammatically a preferred system in which this invention is embodied;

FIGURE 2 is a view, partly in side elevation, and partly in section, showing a portion of the driving mechanism to the phase shifter; l

FIGURE 3 is a view, in `side elevation and somewhat diagrammatic in character, illustrating how the present invention can be embodied, in part, in tape recording apparatus; and

FIGURE 4 is a top plan view of the tape recording apparatus shown in FIGURE 3 and illustrates diagrammatically how the tape recordinng apparatus can be reversed to provide for continuous operation of a clock or similar mechanism.

In my copending application Serial No. 708,187, tiled January 10, 1958, I have disclosed a system for remotely operating the hour hand of a clock through the use of a fundamental frequency and a second harmonic and then shifting the phase of the second harmonic with respect to that of the fundamental in predetermined 0 "ice manner so as to eifect rotation of the hour hand to provide an indication of time. The reason for choosing to operate the hour hand is that the remotely located clock may be energized at a time which is different from the time that is being indicated. It is necessary that the time indication be changed to the correct time indication which can be accomplished by energizing the remotely located clock with the fundamental and second harmonic in the manner described. Then as the control system continues to operate, the hour hand continues to advance and to show the correct time. When it is desired that there be an indication of minutes as well as hours, a gear train can be interposed between the hour hand and the minute hand as disclosed in my copending application Serial No. 576,564, filed April 6, 1956. For this purpose a gear train having a ratio of one to twelve is required in order to rotate the minute hand twelve times for each rotation of the hour hand of a conventional clock. Because of the inherent backlash in such a `gear train, the minute hand may be inaccurately positioned.

In order to avoid the use of such a gear train and still provide for accurately indicating time, provision is made in accordance with this invention to drive the minute hand as the result of the control of' the phase relations between the fundamental and the second harmonic and then to periodically advance and reverse the movement of the minute hand to operate the hour hand. This operation may take place once each minute and may require a few seconds to accomplish it. Alternatively the periods may be spaced further apart, such as every fifteen minutes, as may be desired.

While the present invention is directed particularly to the remote operation of the hands of a clock, it will be apparent that it can be employed for controlling the operation of two indicators, each of which indicates a different variable. Further, while the variables in a clock are dependent, it is unnecessary that the variables be dependent on each other. In otherY words, they can be independent variables.

The system disclosed herein employs for the most part the control system shown in FIGURE 2 of copending application Serial No. 708,187, filed January 10, 1958. Accordingly, the same reference characters are employed insofar as possible in the instant description that are used in this copending application.

Referring now particularly to FIGURE 1 of the drawing it will be observed that the reference characters 10 and 11 designate conductors which comprise a load circuit that is arranged to be energized with alternating current comprising a fundamental land a second harmonic. For this purpose a source 12 of frequency f, such as 60 cycles per second, is connected through a phase shifter, shown generally at 13, which is energized from a source 14 having a frequency of 2f or double that of the source 12, across the load circuit comprising the conductors 10 and 11. The source 12 can be volt alternating current source such as is used customarily for household purposes. However, it will be understood that the frequencies referred to are for i1- lustrative purposes and that higher or lower frequencies can be employed, the important factor is that a frequency of one source, i.e., the source `14, is double that of the other source, i.e., the source I12. While conductors 10 and 11 are illustrated as providing connections to the load, it will be understood that the two alternating currents can be employed for modulating a radio transmitter in the manner described in my copending application Serial No. 576,564, tiled April 6, 1956, for remote operation through a radio receiver of devices such as clocks located, for example, in vehicles such as automobiles or airplanes. While the source 12 and phase shifter 13 are illustrated as being connected in series circuit relation, it will be understood that they can be connected in parallel. Further, it will be understood that they can be connected inductively rather than directly to the load circuit formed by the conductors and 11.

It will be observed that the source 14, which may have a frequency of 120 cycles, is a three phase source. As shown energy from the source 14 is applied to the phase shifter 13. The phase shifter 13 comprises a stator core 22 around which there is a stator winding 23 that is closed on itself and is tapped at locations 120 apart for connection to the terminals of the three phase source 14, as shown. Mounted for rotation within the stator 22 and stator winding 23 is a rotor 24 which is provided with `a rotor winding 25. The rotor 24 is mounted for rotation on a shaft 26. Slip rings 28 are mounted on the shaft 26 for making connection to the rotor winding 25 in a conventional manner. As shown in the drawings, the rotor winding 25 in which frequency 2f is induced is in series with the source 12 of frequency f. The phase relationship between the frequency of the source 12 and the frequency from the source 14 can be adjusted by changing the position of the rotor 24. This can be accomplished manually or through the agency of a motor for a combination of motors for moving the rotor 24 in a manner hereinafter described to effect the phase shift in a predetermined manner.

The output of the source 12 `generating a fundamental frequency and the output of the source 14 generating a double frequency or second harmonic of the frequency generated by the source 12, controlled by the phase shifter 13, are employed in accordance with this invention for controlling the operation of a motor that is indicated, generally, at 30. The motor 3&1 includes a rotor 31 in the form of an annular core of permanent magnet material which is magnetized, as indicated7 along a diameter. It is preferable to employ the annular form for the core 31 although it will be understood that a bar type of rotor can be employed. Also an electromagnetic rather than a permanent magnet can be employed for the rotor of the motor 30. The annular core 31 is mounted on a circular hub 32 which in turn is mounted on a shaft 33 on which a minute hand 34 is mounted for conjoint rotation. It will be understood that the minute hand 34 rotates synchronously with the rotation of the rotor 24 of the phase shifter 13. Surrounding the annular core 31 is a core 35, annular in form and made of transformer steel. It may be made up of a single strip of transformer steel spirally wound to provide the annular core shown. Pairs of windings 36-36 and 37-37 are provided on the core 35. For illustrative purposes they are shown in spaced relation on the core 35. It will be understood that each of these windings is in the form of a coil around the core 35 and are connected, as shown, so that on liow of direct current therethrough they generate magnetic fields at right angles to the diameters through the respective pairs of windings 36-36 and 37-37. if desired, a damping ring can be provided between the annular core 31 -of the rotor and the annular core of the stator.

It is desirable that the phase angle of the two circuits including the pairs of windings 36--36 and 37-3'1 be different. For -this purpose an inductor 38 is connected in series circuit relation with the winding circuit comprising the windings 36-36. Included in the circuit s a nonlinear resistor 39 which has no rectifying characteristics and can be formed by a space discharge type of device such as a neon tube. Also it may comprise germanium diodes connected in opposition or a tungsten larnent lamp. Also the non-linear resistor 39 can be formed of silicon carbide or a sintered compound of barium oxide and iron oxide. The other winding circuit comprising the windings 37-37 is connected through a capacitor having in parallel therewith a resistor 41, and through a non-linear resistor 42. If desired, the resistor 41 can be omitted and the capacitor 40 can be connected across windings 37-37 in series to obtain the proper phase angle. It will be observed that the two winding circuits are connected in parallel relation between the conductors 10 and 11 which are in effect extensions of the conductors 1t) and 11. The conductors 10 and 11 are shown, in part, by broken lines to indicate that the motor 30 is located at an indeterminate distance from the sources 12 `and 14 and the phase shifter 13. Also the broken lines indicate that the link may be provided through a radio transmitter and receiver in the manner described.

The inductor 38 and capacitor 40 can be omitted where the non-linear resistors 39 and 42 have opposite characteristics. For example, silicon carbide and tungsten have opposite characteristics.

It has been pointed out that the minute hand 34 rotates synchronously with the rotor 24 of the phase shifter 13. Provision is made for rotating the rotor 24 at a speed of one revolution per hour in order to advance the minute hand 34 in a corresponding fashion. In addition, provision is made, as indicated hereinbefore, for advancing and reversing the rotation of the minute hand 34 periodically. This may occur once each minute, one each iive minutes, once each fteen minutes, etc., as may be desired. Accordingly, the minute hand 34 is provided with a detent 45 which is arranged to engage iirst one side and then the other side of an hour hand 46 which always remains in the position to which it is moved as the result of contact by the detent 45 on the minute hand 34. Any suitable means can be provided for mounting the hour hand 46 to operate in this fashion. For example, the hour hand 46 can be mounted on a sleeve 47 for rotation therewith. The sleeve 47 is journaled on a stationary bushing 48. The minute and hour hands 34 and 46 are arranged to operate past a clock dial 49 on which the hours and minutes are indicated in conventional manner.

In this particular embodiment there is a deiinte relationship between the positions of the minute hand 34 and hour hand 46. However, they may be independent variables and can be employed to indicate temperature and humidity or wind velocity and baronietric pressure. Alternatively, the minute hand 34 could be used to indicate any number from Zero to nine while the hour hand 46 could be employed for indicating any number between rten and one hundred. The clock dial 49 then would be provided with corresponding indications as might be required.

It will be understood that the phase shifter 13 is operated to advance the rotor 24 at such speed as to move the minute hand 34 at a speed of one revolution per hour. Then provision is made for advancing the rotor 24 at a higher speed. This advances the minute hand 34 and the detent 45 engages the hour hand 46 in any position in which it may be located between the position of the minute hand and the position of the hour hand 46 where the correct time is indicated. Then the minute hand 34 isfreversed through 360 so a-s to engage the opposite side of the hour hand 46 in the event that it does not occupy the proper position for moving it to the correct time indicating position. Then the minute hand 34 is advanced to the correct position showing the proper time. Of course the hour hand 46 does not advance continuously and, accordingly, except for the initial positioning thereof for each movement of the minute hand 34, for example when it is reversed once every tive minutes, as far as it is concerned the hour hand by itself shows the time correctly l2 times each hour. However, the only reason for employing the hour hand 46 is to indicate the particular hour after which the minute hand 34 indicates the number of minutes past the hour. Thus it is relatively unimportant that the hour hand 46 be continuously moved. Moreover, such movement is relatively imperceptible and reliance must be placed on the position of the minute hand.

, advance or an hour later as the case may be.

34 in order to obtain an accurate indication of time. It remains to describe how the rotor 24 of the phase shifter 13 is operated rst at a fixed speed to advance the minute hand 34 and then at a higher speed to advance the hour hand 46.

For operating the rotor 24 in the manner described, a shaded pole motor 52 is employed. It includes a rotor 53 of the squirrel cage type that is mounted on the shaft 26 for driving the same. An energizing winding 54 is provided for rotating the rotor 53 in one direction or the other depending upon the energization of a reversing winding 55. The manner in which the windings 54 and 55 of the motor 52 are energized will be described presently.

At the outer end of the shaft 26 there is mounted a flat blade 56 which is lformed of relatively thin material. The blade 56 extends radially from a collar 57 which is secured by a set screw 58 to the shaft 26. The movement of the blade 56 and thereby movement of the shaft 26 and rotor 24 is limited by an hour hand stop 59 which extends laterally from a gear 60. The gear 6d is carried by a hub 61 which is rotatable and slidable on the shaft 26. It is held in the position shown in FIGURE 2 by a spring 62 against a collar 63 which is secured -to the shaft 26 by a set screw 64. The spring 62 reacts between the collar 57 and the gear 60 to hold the latter in the positionshown. The gear 60 is driven at a speed of g revolution per hour through a pinion 65 which is driven by a synchronous motor 66. It will be understood that the synchronous motor 66 operates through a -suitable reduction gear train to drive the pinion 65. The arrangement is such that the position of the hour hand stop 59 corresponds to the position of the hour hand 46 and that an arrangement is made, as will be described hereinafter, for moving the hour hand 46 so that it indicates the position of the hour hand stop 59 and thus indicates the correct time insofar as hours are concerned. When Iit is desired ot advance or retract the hour hand 46, for example on the occurrence of daylight time or change from daylight time, the gear 60 can be moved, as indicated at 67 in FIGURE 2, out of driving engagement with the pinion 65 and then rotated to indicate one hour in A suitable dial associated with the `gear 60 indicates the time, if desired.

In order to rotate the rotor 24 and advance the minute hand 34 at a speed of one revolution per hour a minute hand stop 70 is provided and is arranged to cooperate With the blade 56 which, it will be recalled, extends from and rotates with the shaft 26. The minute hand stop 70 extends laterally from a magnetic disc 71 which is carried by a sleeve 72 that is provided with a key 73 that extends into a slot 74 in a shaft 75. Thus the magnetic disc 71 and minute hand stop 70 carried thereby rotate conjointly with the shaft 75. However, the magnetic disc 71 is movable along 4the shaft 75 in order to move the minute hand stop 70 out of the path of the blade S6. A coil compression spring 76 reacts against the magnetic disc 71 and holds it in the position where the minute Yhand stop 70 is in the path of the blade 56 and can advance the same on rotation of the shaft 75 and magnetic Vdisc 71. In order to attract the magnetic disc 71 and move the minute hand 70 out of the path of the blade 56 a coil 77 is provided and is arranged to be periodically energized in a manner to be described hereinafter. The

'coil 77 is stationarily' mounted within a stationarily mounted magnetic cup 78. On energization of the coil 77, the magnetic disc 71 is moved as indicated at 79 in FIGURE 2, toward the magnetic cup 78. `On deenergization of the coil 77, the magnetic disc is moved out-v wardly by the spring 76. The shaft 75 is rotated at a speed of one revolution per hour by a gear 80 which is driven by a pinion 81 that is rotated by a synchronous motor 82. It will be understood that the synchronous -.motor 82 drives through a suitable gear reduction mechat5 nism and that the synchronous motor 66 can be employed to drive not only the pinion 65 but also the pinion 81. For illustrative purposes two motors 66 and 82 are shown but a single motor can be used as indicated.

The shaded pole motor 52 and the synchronous motors 66 and 82 are energized from a suitable alternating current source indicated by the conductors 85 and 86 which are connected across the source 12 which, as indicated, is a conventional 60 cycle 115 volt source. The conductors 85 and 86 are also arranged to energize a third synchronous motor 8'7 although it will be understood that the motor 66 can be arranged to operate the mechanism driven by the motor 87 but for illustrative purposes a separate motor is shown. The synchronous motor 87 rotates a pinion 88 which is arranged to drive a gear 89 at a speed of one revolution per minute. If it is desired to set the hour hand 46 less often than once each minute, the speed at which the gear 89 is driven is correspondingly reduced. The gear 89 is secured to and rotates with a shaft 90 on which are fixed cams 91, 92 and 93. The gear 89 rotates in the direction indicated by the arrow 94 and the cams 91, 92 and 93 are so arranged that within a given time, such as an interval of three seconds, normally open contacts 95 are closed, then normally open contacts 96 are closed and thereafter normally closed contacts 97 are opened and normally open contacts 98 are closed.

In describing the operation of the system shown in FIGURE 1 of the drawings it will be assumed that the correct time is as indicated by the minute hand 34 and the hour hand 46. However, it will be assumed that the motor 39 has been disconnected from the conductors 10 and 11 and that the hour hand 46 occupies a position in the vicinity of six oclock. However, under assumed conditions, the hour hand stop 59 is in a position corresponding yto a few minutes past eleven oclock.

With all of the circuits energized and the elements operating in the manner indicated hereinbefore, the rotation of the shaft 90 by the gear 89 causes the closure of contacts 95 to complete an energizing circuit for the coil 77 through a rectifier 99. A capacitor is connected across the conductors 85--86. The circuit including the rectifier 99 and capacitor 100 provides a direct current supply for the coil 77. As a result of the energization of coil 77, the magnetic disc 71 is attracted and the minute hand stop 70 is moved out of the path of the blade 56.

Shortly after the contacts 95 are closed, the cam 92 closes contacts 96. As a result of the closure of the contacts 916 the winding 54 is connected for energization across the conductors 85-86 while the reversing winding 55 remains connected by normally closed contacts 97 to the terminal of the winding 54 that is connected to the conductor l86. The lrotor 53 of the shaded pole motor 52 then rotates the rotor 24 of the phase shifter 13 in a clockwise direction until the blade 56 engages the hour hand stop 59 and effects a corresponding shift of the phase of the alternating current from the source 14 with respect to the phase of the alternating current from the source 12. 'Ihe minute hand 34 is advanced thereby and the detent 45 engages the hour hand 46 in the assumed position in the vicinity of six oclock and tmoves it to the position shown in the drawings slightly past eleven oclock.

Next the cam 93 operates to open the contacts 97 and close the contacts 98. This reverses the rotation of the rotor 53 of the shaded pole motor 52 and the arrangement is such that the rotor 24 is rotated through 360 where the blade 56 engages the other side of the hour hand stop 59 thereby causing the minute hand 34 to rotate through a similar extent and the detent 45 to engage the other side of the hour hand 46 as the result of counterclockwise rotation of the lminute hand 34.

Next the cam 9.1 is moved to open contacts 95, deenergizing coil 77 and allowing the magnetic disc 7 1 to 7 be moved outwardly by the spring 76 to position the minute hand stop 70 in the path of the blade 56.

The cam 93 now operates to open contacts 98 and close contacts 97. This causes the rotor 53 of the shaded pole motor 52 to rotate in a clockwise direction and bring the blade 56 against the minute hand stop 70. A corresponding movement of the minute hand 34 takes place and it is moved to indicate the correct time. Finally the cam 92 operates to open contacts 96.

Thereafter the minute hand stop 70 continues to allow advance of the blade 56 and thereby to permit operation of the phase shifter 13 in the manner `described to cause rotation of the minute hand 34 whose position indicates the correct minutes after the hour. The blade 56 is held against the minute hand stop 70 by torque generated by the phase shifter 13 acting like an induction motor due to the load applied to the rotor winding 25 from the load circuit represented by the conductors 10 and 11.

It will be understood that the operation of the cams 91, 92 and 93 to eifect the functions above described takes place during a relatively short period of time. For example, the period may be of the order of one to three seconds. During the remaining part of the minute, the minute hand 34 is advanced in the usual manner for a clock. As pointed out, the cams 91, 92 and 93 can be operated once each rive minutes or once each fteen minutes as Imay be desired since the exact position of the hour hand -46 at particular time is not critical.

It will be observed in FIGURE l that the conductors 10 and 11 are connected to terminals 101 and 102. It will be understood that any suitable means which will apply the two alternating currents to the terminals 1011 and 102 and shift the phase of one with respect tothe other in the manner described can be used for operating the motor 30 in turn to operate the clock hands 34 and 46 to indicate time or to give other indications of other variables as may be desired.

Referring now to FIGURES 3 and 4 of the drawings, it will be observed that two motors 30 are shown as being connected for energization across the conductors 10 and 11 and to the terminals 101 and 102. As many motors 30 as are required can be connected to conductors y10 and 11' to indicate time or other variables at various pla-ces.

Where the particular indication is a time indication, it is possible to record the wave form which appears between the conductors 10 and `1.1 of FIGURE l on magnetic tape, such as the tape 105 indicated in FIGURES 3 and 4. The magnetic tape 105 is arranged to be wound and unwound from reels 106 and 107. A reproduce head 108 cooperates with the magnetic tape 105 for picking up the wave form.

When a time indication is to be given, it is desirable that the tape 105 be so arranged and operated that the motors 30 are driven continuously. For this purpose two Wave forms or tracks 109 and 110 are recorded on the magnetic tape 105 in opposite directions as indicated by the arrows 1111 and 112. Provision is made for shifting the position of the reproduce head 100 or a second reproduce head 108 can be used, as illustrated, and it is selectively connected with the reproduce head 100 by a double pole double throw switch 113 to an amplifier 114 which is connected, as shown, to the terminals 101 and 102. Provision is made yfor driving and holding back the reels 106 and 107 by the reel drive and hold back mechanisms `116 and 117 as indicated. Sprockets 118 and 119 are arranged to be `driven alternately by the mechanisms 116 and 117 and they engage perforations 120 in the tape 105 to insure that it is moved past the heads 108 and 108 at a `xed speed.

Once the Wave forms or tracks 109 and 110 have been recorded on the magnetic tape .105, it is possible to dispense with the phase shifter 13 and apparatus `for controlling the same described hereinbcfore. However, it is necessary to periodically reverse the tape 105 and operate the switch 113 in accordance with the reversal of the tape 105. For this purpose the synchronous motor 82 can be employed for driving through the pinion 81, and gear to a gear 121 which is mounted on a shaft 122 that `drives a mechanism 123 for reversing the tape [05 by suitably controlling the mechanisms 115 and -117 and the reversing switch 113.

When the magnetic tape is endless and provision is made for driving it continuously in one direction, it is unnecessary to provide the second track or the reversing mechanism.

Since certain further changes can be made in the foregoing construction, system and method and different embodiments of the invention can be made without departing Ifrom the spirit and scope thereof, it is intended that all matter shown in the accompanying drawings and described hereinbcfore shall be interpreted as illustrative and not in a limiting sense.

What is claimed as new is:

l. Time indicating means comprising, in combination, a rotatable minute hand, an hour hand freely rotatable with respect to said minute hand about its aXis of rotation, a detent on said minute hand engageable with said hour hand, means for rotating said minute hand at a uniform speed, and means for periodically rapidly advancing the minute hand to move said hour hand to the correct time indicating position.

2. Time indicating means comprising, in combination, a rotatable minute hand, an hour hand freely rotatable with respect to said minute hand about its axis of rotation, a detent on said minute hand engageable with said hour hand, means for rotating said minute hand at a uniform speed, and means for sequentially rapidly advancing and reversing the rotation of said minute hand to cause said detent to drive said hour hand from one side and then the other to move said hour hand to the correct time indicating position.

3. Time indicating means comprising, in combination, a rotatable minute hand, an hour hand freely rotatable with respect to said minute hand about its axis of rotation, a detent on said minute hand engageable With said hour hand, an electric motor connected to said minute hand, means for energizing said electric motor to rotate said minute hand at a uniform speed, and means for periodically changing the energization of said motor to sequentially rapidly advance and reverse the rotation of said minute hand to cause said detent to drive said hour hand from one side and then the other to move said hour hand to the correct time indicating position.

4. Time indicating means comprising, in combination, a rotatable minute hand, an hour hand freely rotatable with respect to said minute hand about its axis of rotation, a detent on said minute hand engageable with `said hour hand, an electric motor connected to said minute hand, means for energizing said electric motor with two alternating currents the frequency of one of which `bears a fixed relation to that of the other, means for shifting the phase of one of said currents with respect to the phase of the other current to rotate said minute hand at a uniform speed, and means for periodically advancing and retarding the phase of said one current with respect to that of the other current to sequentially rapidly advance and reverse the rotation of said minute hand to cause said detent to drive said hour hand from one side and then the other to move said hour hand to the correct time indicating position.

5. The invention as set forth in claim 4 wherein a tape has the wave form of the two alternating currents recorded thereon, reproduce head means in operative relation to said tape and electrically connected to the electric motor, and means for operating the tape at predetermined speed to operate said electric motor and thereby the minute and hour hands.

6. The invention as set forth in claim 4 wherein a tape has the wave form of the two alternating currents recorded along two tracks in opposite directions thereon, reproduce head means in operative relation to said tape and electrical- 1y connected to the electric motor, and means for operating said tape at predetermined speed in one direction and then in the opposite direction to operate said electric motor and thereby the minute and hour hands continuously.

7. In combination, means for generating two alternating currents, one having a frequency twice that of the other, means for shifting the phase of one of said currents with respect to that of the other current at a uniform speed, means for periodically advancing and retarding the phase of said one current with respect to the phase of the other current, non-linear resistance means energized by said two alternating currents and providing flows of direct current, means energized -by said flows of direct current and operating in response to said phase shift, and non-linear resistance means in series with said responsive means for modifying said currents.

8. `=In combination, means for generating two alternating currents, one having a frequency twice that of the other, means for shifting the phase of one of said currents with respect to that of the other current at a uniform speed, means for periodically advancing and retarding the phase of said one current with respect to the phase of the other current, non-linear resistance means energized by said two alternating currents and providing iows of direct current, means energized by said ows of direct current generating a unidirectional magnetic field the position of which changes in response to phase shift, means responsive to said unidirectional magnetic field capable of changing its position in accordance with the movement thereof, and non-linear resistance means in series with said responsive means -for modifying said currents.

References Cited in the file of this patent UNITED STATES PATENTS 555,387 Long Feb. 25, 1896 864,177 Mantaras Aug. 27, 1907 1,860,936 Marrison et al. May 3l, 1932 2,236,374 Marrison Mar. 25, 1941 2,562,682 Schmitt July 31, 1951 2,582,957 Borsum etal Jan. 22, 1952 2,861,255 Mechler et al Nov. 18, 1958

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