US2260808A - Time system - Google Patents

Description

Oct. 28, 1941. JACKSQN 2,260,808

TIME SYSTEM Filed Aug. 9, 1939 INVENTOR. Edward B. Jackson.

ATTORNEY Patented Oct. 28, 1941 TIME SYSTEM Edward B. Jackson, Downers Grove, Ill., vassignor to General Time Instruments Corporation, New York, N. Y., a corporation-of Delaware Application August 9, 1939; Serial No. 289,089

1 Claim.

vThe present invention relates in general to time systems, more particularly to a corrective time system in which each secondary apparatus is controlled and periodically corrected or synchronized by a primary or master apparatus. The. main object of the invention is the provision of a simplified system of this type for use especially where alternating current is employed as the source of power.

Another object of the invention is to provide a system requiring only a two wire circuit between the master apparatus and the secondary apparatus and requiring only one source of current supply.

According to a particular feature of the invention the normal operating impulses are transmitted over the control circuit as alternating current impulses and are rectified at each individual secondary apparatus in order to provide proper operating current for the secondary magnets.

According to another feature of the invention the secondary apparatus is rendered responsive and unresponsive to the impulses received over the control circuit by selectively shunting out a rectifier which is in series with the operating magnet of the secondary apparatus.

According to a further feature of the invention an impulse of rectified current is periodically transmitted over the control circuit in order to advance all secondary apparatus from a predetermined stop position.

Other features and objects of the invention will become apparent from the following description when read in connection with the accompanying drawing comprising one figure only and which illustrates by means of the usual schematic circuit diagram the preferred embodiment of the present invention.

Referring to the single figure of the drawing, the letter M indicates the master or control apparatus which comprises a master clock movement (not shown) embodying the contacts 3, 5,

I '6 and 10. Contacts 3 are closed once each minute by a suitable cam 4.

Contacts 5 are controlled by a cam on the minute shaft of the master clock movement and may be arranged to close at approximately fifty-nine minutes and ten seconds after the hour and to open at approximately fifty-nine minutes and forty seconds after the hour. Contacts 6 are arranged to be closed momentarily every two seconds by suitable connections with the verge of the master clock escapement. The contacts 10 are controlled by a cam on the minute shaft of the master clock movement and may be arranged to open at approximately fifty-nine minutes and fifty seconds after the hour and to remain open at least until after the hour position has been passed and longer if desired. The master apparatus M also includes an impulsing relay 1 and a rectifier unit 9 which is normally short-circuited by the contacts l0.

SI and S2 indicate secondary apparatus and each comprises an operating magnet such as l3 which is connected to the control circuit in series with a rectifying unit such as [4. Contacts such as [5 are arranged to short-circuit the rectifying unit l4 and are controlled by a cam on the minute shaft of the secondary apparatus. This cam is preferably arranged to close the contacts only in position fifty-nine during each hourly cycle of operation. Only those parts of the apparatus which are essential for a complete understanding of the invention have been shown on the drawing.

Having briefly described the apparatus shown on the drawing, a detailed explanation of the operation of the system will now be given.

Referring to the drawing, the contacts 3 of the master apparatus M are momentarily closed once each minute by means of the cam 4 which is mounted on the seconds shaft of the master clock movement. The closing of these contacts completes a circuit from the alternating current line I, contacts 3, winding of impulsing relay 1 to the alternating current line 2. Relay 1 is momentarily operated and at its contacts 8 transmits an alternating current impulse over the control circuit from the alternating current line 2, contacts 8, conductor 12, conductor I8 of SI, rectifier M, winding of magnet l3, conductor l1, line II, contacts Ill to alternating current line I. Similar circuits extend from line conductors II and I2 through the other secondary apparatus such as S2. The operating magnets of the secondary apparatus are operated by the alternating current impulse which is rectified at each individual apparatus by means of the rectifier such as M. The secondary apparatus such as SI and S2 are, therefore, advanced once each minute by impulsestransmitted from the master apparatus and are normally kept in synchronism therewith. It should be explained at this point that the operating magnets of the secondary apparatuses are responsiveto half-wave or fullwave rectified alternating current but will not be operated by alternating current impulses.

It is possible that the secondary apparatuses may become scattered due to improper setting or due to failure of one of the operating magnets to respond to one or more impulses. The system is, therefore, arranged so that the secondary apparatuses will be corrected periodically, for example, once each hour. This is accomplished in the following manner.

Shortly after the master clock has passed its fifty-ninth minute contacts 5 are closed by a suitable cam on the minute shaft and connect the fast contact 6 in the circuit of the impulsing relay I. As previously stated, the contacts 6 are controlled by the verge of the master clock escapement and are arranged to be closed momentarily once every two seconds. Thus the impulsing relay is momentarily operated every two seconds and at each operation it closes its contacts 8 to transmit an alternating current im pulse over the control circuit comprising lines II and I2. Thus any secondary apparatus which is slow and is not in synchronism with the master clock will be rapidly advanced to its fifty-ninth minute position. In the drawing secondary apparatus S2 has been indicated as fast or on time whereas secondary apparatus SI has been shown as being slow. Thus it will be seen that cam 22 of S2 has closed contacts 2| thereby short-circuiting the rectifier 20. Further impulses received over the control circuit do not operate magnet I9, since this magnet is designed so that it will not respond to alternating current impulses. minute position during the remainder of the normal minute impulses and the fast impulses.

SI is indicated as being slow and the contacts I are, therefore, still open when the master apparatus sends out the fifty-ninth Shortly thereafter, for example, at fifty-nine minutes and ten seconds after the hour, contacts 5 are closed, as previously explained, and the rapid accelerating impulses are transmitted over the control circuit. Each of these impulses operates magnet I3 thereby rapidly advancing the secondary apparatus SI to its fifty-ninth minute position. When it reaches such position cam I6 closes contacts I5 thereby shunting rectifier I4 and rendering the operating magnet I3 unresponsive to further alternating current impulses.

At approximately fifty-nine minutes and forty seconds after the hour the contacts 5 are open thereby removing the fast contacts 6 from the circuit of impulsing relay I and terminating the series of rapid accelerating impulses. At approximately fifty-nine minutes and fifty seconds after the hour contacts ID are opened thereby removing the shunt from rectifier 9. When contacts 3 are then closed in the hour position of the master apparatus a rectified alternating current impulse is transmitted over the control circuit II-I2. Since this sixtieth impulse has been rectified the magnets such as I3 and I9 are operated thereby and at the termination of the impulse advance their respective movements into position sixty. In this position contacts I5 and 2I are again opened reinserting the rectifiers I4 and into the circuits of magnets I3 and I9, respectively. Thus all of the secondary apparatuses are stepped up in synchronism with the master clock by the rectified alternating current impulse which is transmitted over the control circuit when the master apparatus reaches position sixty. In order to insure the proper advance of all secondary apparatus and the opening of the cam contacts such as I5 and 2|, contacts I0 of the master clock may be arranged to remain open for several minutes so that two or more of the succeeding minute impulses will be rectified by the rectifying unit 9.

From the foregoing detailed explanation it will be seen that the secondary apparatuses are normally operated by alternating current impulses transmitted over the control circuit. Such im- S2, therefore, remains in its fifty-ninth I impulse.

pulses are rectified in each individual secondary apparatus in order to provide proper operating current for the magnets. As each secondary apparatus reaches its fifty-ninth minute position its rectifying unit is short-circuited thereby rendering its operating magnet unresponsive to alternating current impulses received over the line. A series of rapid accelerating alternating current impulses is transmitted by the master apparatus between the fifty-ninth and sixtieth minute in order to rapidly advance any secondary apparatus which may be slow. When the master apparatus reaches position sixty it transmits an impulse of rectified alternating current over the control circuit in order to operate all the secondary magnets irrespective of Whether or not the associated rectifiers are in the circuit. In case more than one rectified alternating current impulse is transmitted by the master clock the rectifiers, such as I4 and 20, must of course be properly poled with respect to the rectifier 9.

From the foregoing it will be apparent that this invention provides a corrective time system requiring only a two wire circuit between the master and secondary apparatus and which does not require the use of reversed current, current of two voltages or alternating current of two frequencies. The corrective feature can, therefore, be easily applied to existing time systems operated by alternating current impulses since it requires only the addition of the cam contacts in each secondary apparatus and the addition of contacts 5, 6 and I0 and rectifier 9 in the master apparatus.

Having thus described the invention what is claimed as new and is desired to have secured by Letters Patent is:

In a corrective time system, master apparatus and secondary apparatus connected by a control circuit, a source of alternating current connected to said master apparatus, means in said master apparatus for transmitting normal alternating current impulses from said source over said control circuit at regularly recurring intervals, an electromagnet in said secondary apparatus unresponsive to alternating current flowing through its windings, a rectifier normally in series with said electromagnet to rectify said alternating current impulses whereby said secondary apparatus is advanced step by step by the operations of said electromagnet, means in said master apparatus for transmitting a series of rapidly recurring alternating current impulses over said control circuit between two of said normal impulses, means in said secondary apparatus operative when the same reaches a predetermined chronological position for shunting said rectifier to render said electromagnet inoperative by alternating current impulses, a rectifier in said master apparatus, a normally closed shunt circuit for said rectifier, and means for opening said shunt circuit immediately following the transmission of said series of rapid impulses whereby an impulse of rectified alternating current is transmitted over said control circuit to operate said secondary electromagnet thereby opening the shunt around said secondary rectifier to again render said electromagnet responsive to the normal alternating current impulses.

EDWARD B. JACKSON.

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