Annunciator

Oct. 16, 1951

A. Η. B. WALKER

ANNUNCIATOR

Filed Aug. 13, 1947

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INVENTOR.

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SWORNEY is

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Patented Oct. 16, 1951

2,571,973

UNITED STATES PATENT OFFICE

2,571,973

ANNUNCIATOR

Alec Hervey Bennett Walker, London, England, assignor, by mesne assignments, to Westinghouse Air Brake Company, a corporation of Pennsylvania

Application August 13, 1947, Serial No. 768,410 In Great Britain August 19,1946

Claims.

This invention relates to annunciators of the kind used for making verbal announcements such as may be used for the conveyance of information or instructions to a congregation of people, for advertising and for like purposes, the announcements having been pre-recorded and being selected as and when required by manual or automatic means.

The annunciator may be advantageously employed, for example, at a railway station for the announcement of train departures, stopping stations and similar information and may be controlled by, or in conjunction with, the usual visual train describer system.

According to the invention, the required announcements are recorded on some form of magnetic wire or tape, such as impregnated plastic tape, by any suitable means and when it is desired to make any particular announcement the corresponding wire or tape is fed past an associated reproducing or pickup head. A number of tapes, each containing an announcement or announcements may be provided, a single motor driven shaft being employed to feed any selected tape through its associated pickup head and the feed being automatically interrupted at the end of the announcement.

The invention is illustrated, by way of example, by the accompanying drawing, Figure 1 of which is a diagrammatic view of one form of apparatus embodying the invention, Figure 2 being a view, also mainly diagrammatic, along the lines II—H of Figure 1. Figure 3 is a diagrammatic view showing the reproducing means which is common to the several individual pickup heads.

Referring now to the drawing, in one form of annunciator constructed in accordance with the invention, a number of magnetic tapes I, in the form of continuous loops, upon each of which is recorded one or more announcements, are hung side by side each over a pair of longitudinally displaced pulleys 2 and kept in moderate tension by means of a loaded roller or pulley 3 which engages the lower or hanging part of the loop. Between the two longitudinally displaced pulleys the tape passes through a pickup head 4 of any suitable kind and over a shaft 5 which may be continuously rotated by means, for example, of a suitable electric mbtor 6.

The pickup head 4 is connected by means of leads 7 to a suitable form of amplifier and announcing apparatus. As shown in Figure 3 the individual pickup heads are connected in multiple across the input of an amplifier AM the output of which is connected to a primary winding (Cl. 179—1) of a transformer Tl. The amplifier AM may be of standard form which is effective to amplify voice frequency energy. As shown in Figure 1, one secondary winding 13 of the transformer Tl ⁵ is connected to an announcing device such as a loudspeaker LS. A second secondary winding 14 of the transformer Tl is connected to an automatic interrupting circuit to be described shortly.

¹⁰ The tapes I are not normally in contact with the rotating shaft 5 the latter being mounted slightly below said tapes. Above each tape, at the point where it passes over the rotating shaft, is mounted a roller 8 which is normally held ¹⁵ out of engagement with the tape by any suitable means such as a biassing spring 9. The energisation of a solenoid 10 causes the downward movement of the roller which forces the tape down on to the rotating shaft. The tape, being 20 thus gripped between the roller 8 and the shaft 5 is fed past the pickup head 4 which detects the announcement recorded on the tape.

The tape will evidently continue to be fed past the pickup head as long as it is gripped between 25 the roller 8 and the rotating shaft 5. In order to stop the tape automatically, there may be recorded thereon, at the end of the announcement a short period of alternating current preferably of sub-audible frequency. This recorded 30 alternating current is detected by the pickup head and amplified in the usual way. The secondary winding 14 which is coupled to the amplifier is tuned by a capacitor to form a tuned circuit responsive only to the predetermined frequency. 35 The output from this tuned circuit is connected to a relay 15 through a rectifier IS to operate the relay to de-energise the solenoid 10, in a manner to be described shortly, and thus allowing the biassing spring 9 to withdraw the roller 40 8 from the tape I which, being no longer gripped between the roller and the rotating shaft, will come to rest.

The movement of the tape to give an announcement may evidently be initiated by the energisa45 tion of the solenoid 10 upon the closure of a switch or the reception of an electrical impulse from other apparatus or, if desired, the roller may be caused to press the tape against the rotating shaft by manual or mechanical means. As here 5Q shown, each solenoid 10 is controlled by a relay 17 and a manually operable selector switch 18. The switch 18 is spring biased to an open position and when closed it completes an obvious pickup circuit to energize the relay 17. The relay 5.5 ITwhen picked up completes a stick circuit which

2,571,973 retains the relay picked up after the switch i 8 is restored, this stick circuit including a front contact 19 of the relay 17 and a back contact 20 of the relay 15. Relay 17 on picking up closing its front contact 21, completes an obvious circuit for the solenoid. iO. Thus with, the switch 18 closed, the corresponding solenoid 10 becomes enengized and the solenoid remains energized until the portion of the tape having the current of predetermined frequency recorded thereon passes the pickup head to energize the relay 15 and open the stick circuit of the relay 17. As shown in Figure 2, each solenoid 10 is provided with a stick relay 17 and a selector switch 18 and the stick circuit of each stick relay 17 includes the back contact 20 of the relay 15. Furthermore, the shaft need not be permanently, rotating, it may be caused to rotate only when an announcement is required. In these and other respects the invention is evidently not limited to the specified embodiment described and illustrated herein.