US3484552A - Speaker shutoff - Google Patents

Description

O. CL WELLS SPEAKER SHUTOFF Dec. 16, 1969 Filed March 2l, 1967 INVENTOR. ORVILLE C. WELLS Ibi 5% @WIIHIIIIIIM` TTQNEWS United States Patent O 3,484,552 SPEAKER SHUTOFF Orville C. Wells, Kansas City, Kans., assignor to Drive- In Theater Manufacturing Company, Inc., Kansas City, Kans., a corporation of Missouri Filed Mar. 21, 1967, Ser. No. 624,821 Int. Cl. H01h 3/16 U.S. Cl. 179--1 5 Claims ABSTRACT OF THE DISCLOSURE A speaker unit containing a loud speaker has a supporting arm projecting therefrom and adapted to selectively mount the speaker unit on an automobile or a stationary post through which electrical wires extend to the loud speaker. Conductive, integral Contact members are provided on the speaker unit and the post in relative positions whereby when the speaker unit is mounted on the post the contact members engage, shorting out the electrical signal to the loud speaker and thereby silencing the speaker without the use of switches having moving parts.

In multiple loud speaker systems such as those used in conventional driveein theaters, individual loud speaker units are temporarily mounted in or on customers automobiles. A typical speaker unit for this purpose has a loud speaker mounted in a housing including a projecting supporting arm adapted to be hooked over a car door or window, the housing carrying a volume control. When the speaker units are not in use, they are stored on suitable supporting arm receiving posts provided adjacent each parking space. However, customers frequently neglect to shut the speaker olf upon leaving the theater and the sounds may be disturbing to other customers or those living in the vicinity of the theater. Thus, theater employees must continually check and shut off speaker units during and after performances.

It has heretofore been suggested to provide shutoif switches on the speaker units which are actuated when the unit is mounted on the post. Such switches, however, have often been proven to be unsatisfactory because of the substantial expense involved in the purchase and installation thereof and their inability to withstand the extremely rough usage to which they are often subjected.

The Shuto for speaker units disclosed herein requires no -moving parts, but, rather comprises contact areas which short circuit or bypass the signal to the loud speaker when the speaker unit rests on the post. `It is the principal objects of the present invention to provide a speaker shuto arrangement which is operable without moving parts; to provide such a shutoff which is simple in both circuit construction and physical construction; and to provide such an arrangement which is inexpensive, substantially foolproof and well adapted for its intended purposes.

Other objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings wherein are set forth by way of illustration and example certain embodiments of this invention.

FIG. l is a fragmentary perspective view showing a post adapted to mount a pair of speaker units thereon when not in operation, the speaker units being electrically connected to the post through flexible electrical cords.

FIG. 2 is a vertical cross sectional view through a speaker unit on an enlarged scale particularly showing a loud speaker therein and electrical circuit components associated therewith.

FIG. 3 is a vertical cross sectional view on an enlarged scale through the upper portion of the post particularly showing components contained within a junction box associated with the post.

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FIG. 4 is a schematic electrical circuit diagram showing the relationship between the post assembly and speaker units.

Referring to the drawings in more detail:

The reference numeral 1 generally indicates speaker units embodying this invention and adapted for use in a drive-in theater system. Each speaker unit 1 comprises a movable electrically conductive housing 2 having a loud speaker 3 mounted therein for directing sound through suitable louvers 4. A flexible electrical conductor cord 5 is directed into the housing 2 and carries a pair of electrical leads 6 and 7 which are respectively connected to opposite ends 8 and 9 of a resistor 10. The resistor 10` is of the type having a movable tap connected to a terminal 11 whereby moving the tap produces a varying potential between the end 8 and terminal 11.

The end 8 of the resistor 10 is connected through a lead 12 to a terminal 13 which is connected to one end or side of the loud speaker voice coil 14. The terminal 11 is connected through a suitable xed resistor 15 to a terminal 16 which is grounded with respect to the housing 2, the housing being entirely or partially of a conductive metal. The grounded terminal 16 is also connected to a terminal 17 which is common with the other end or side of the voice coil 14.

The housing 2 has a supporting arm 18 projecting therefrom and terminating in a downwardly hooked portion 19 whereby the supporting arm is adapted, for example, to engage the window or window ledge of an automobile for retaining the housing in the automobile so that the occupants can easily hear the sound emanating from the loud speaker 3. The rear 20 of the housing 2 has an electrically conductive, low resistance, contact member or area 21 beneath the supporting arm 18 for a purpose described hereinafter.

A rigid stationary post 22 projects upwardly from a position adjacent the automobile parking space and electrical conductors 23 extend upwardly therethrough from a central signal generating system (not sho-wn) adapted to simultaneously provide speaker actuating signals for a large number of speaker units. The post 22 has a junction box 24 mounted on the upper portion thereof with a suitable retaining or depressed section 25 adapted to receive the hook portion 19 for retaining the speaker units when not in use. The junction box 24 has laterally exposed walls 26 of electrically conductive material, such as common metal, and an exposed electrically conductive, low resistance contact member or area 27 thereon which is positioned to contact the area 21 on the speaker unit when the unit is retained on the junction box as shown at 28. A suitable drain hole 29, or the like, may be provided through a wall of the junction box 24 to drain the depressed section 25.

The junction box 24 contains a transformer 30 having an input section 31 receiving electrical signals from. the conductors 23, and an output section 32. The output section 32 is connected through leads 33 and 34 to the respective leads 7 and 6 of the speaker units for directing the output signal across the resistor 10. The lead 33 is grounded at 35 to the walls 26 of the junction box 24 through a lead 36 connected to a mounting screw 37 of a terminal strip 38 contained within the junction box.

In operation, when the speaker unit is mounted on or in an automobile, the signal from the central system conductors 23 are fed into the transformer 30 where they are suitably modified and directed across the resistor 10 within the speaker units 1. The occupant of the car, by turning a control knob (not shown) which moves the tap of the resistor 10, causes the desired strength of signal to pass through the voice coil 14 of the loud speaker 3 to produce an appropriate sound volume. At the conclusion of the entertainment, the automobile occupant replaces the speaker unit on the post by hooking the supporting arm 1S in the depressed section 25 of the junction box 24. In doing so, the contact areas 21 and 27, respectively on the speaker unit and junction box, come into contact, completing an electrical pathway therebetween. When this occurs, current iiows through the current limiting resistor 15 directly to the transformer output lead 33, thus bypassing the voice coil 14 and thereby eliminating any sound emanating from the loud speaker 3 although the volume position of the resistor remains in a sound producing position. The current limiting resistor restricts current tiow through the shorted circuit to a reasonable rate.

With the arrangement above described, sound production is automatically eliminated upon hanging the speaker unit on the post, without the need for complex switches or other devices having moving parts.

It is to be understood that while one form of this invention has been illustrated and described, it is not to be limited thereto except insofar as such limitations are included in the following claims.

What is claimed and desired to be secured by Letters Patent is:

1. In a drive-in system:

(a) a speaker unit having a housing, a loud speaker mounted in said housing, said housing having supporting means associated therewith and adapted to engage an automobile for selectively retaining said housing thereon,

(b) a rest member adapted to receive and retain said housing when not on said automobile, signal means having an electrical signal output section associated with said rest member,

(c) said loud speaker having a voice coil therein one side of said voice coil being electrically connected through an elongated tlexible line to one side of said output section, a current limiting resistor in said housing and having one side thereof electrically connected to the other side of said voice coil and the other side thereof electrically connected through an elongated flexible line to the other side of said signal output section,

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(e) whereby electrical signals from said output section are shunted around said voice coil, thereby preventing actuation of said loud speaker during non-use of said speaker unit.

2. The apparatus as set forth in claim 1 wherein:

(a) said housing is of electrically conductive material and said second contact member is an exposed area of said housing.

3. The apparatus as set forth in claim 1 wherein:

(a) said rest member includes a junction box having electrically conductive walls and said first contact member is an exposed area on one of said walls. 4. The apparatus as set forth in claim 1 including:

side of said current limiting resistor. 5. The apparatus as set forth in claim 1 including:

(a) a plurality of said speaker units respectively connected in parallel relation to said signal output section.

References Cited UNITED STATES PATENTS 3 2,688,657 9/1954 wilson.

2,753,410 7'/ 1956 Melkon.

KATHLEEN H. CLAFFY, Primary Examiner J. S. BLACK, Assistant Examiner U.S. Cl. X.R. 200-6158 (a) a volume resistor in said housing and connected between the sides of said output section, said volume resistor having a movable tap connected to said other

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