CONTROL CIRCUIT WITH PLURAL INDIVIDUAL SELECTABLE CONTROLS

Abstract: An electrical circuit for the control of a parameter of sound, lighting, etc. within an auditorium by a selected one of a plurality of interconnected controlling devices, wherein each of the devices comprises a manual control (R4) for said parameter which is effective upon operation of a latched trigger (G3, G4), the trigger being activated whenever a signal is received from a selection circuit (STROBE) common to all of the devices while a manual switch (SW1) at a selected device is operated, and the trigger becoming unlatched when a subsequent signal is received and the manual switch is not operated.

Description: ■ CONTROL CIRCUIT WITH PLURAL INDIVIDUAL SELECTABLE CONTROLS' This invention relates to electrical control circuits of the kind providing for operator control at any one of plural remote positions after registration of selection by the operator of a controlling device at that position. BACKGROUND ART Control circuits of this kind, although having many- other applications, are commonly employed in motion picture theatres and other auditoriums equipped with public address systems or other forms of amplified sound equipment. By their use a person, or persons, at different parts of the theatre may determine the optimum volume of sound for the comfort of patrons. This has been achieved by locating a multiplicity of controlling devices at individual positions throughout the theatre and providing for control of the sound amplitude at any instant only at a single device which has been selected by the operator and Identified. Hitherto, equipment of this nature has employed electro-mechanical components and has been expensive, cumbersome and not sufficiently flexible in use. DISCLOSURE OF INVENTION It is the..main object of. the invention to provide a control circuit of the above kind which is relatively inexpensive and compact. To this end the invention in one general form consists of a control circuit for an electrical function and comprising a plurality of controlling devices connectable to a control buss of the circuit for said electrical function, and including a selection control circuit common to all of said controlling devices, each one of said controlling devices having a manual control for said function connectable via a semi-conductor switching device to said control buss, a switch manually operable for effecting by means of a signal from said selection control circuit activation of said switching device of a selected one of said controlling devices, and a trigger device effecting activation of said switching device when said trigger device is latched by operation of said manual switch and simultaneous receipt of said signal and becoming unlatched upon receipt of a subsequent one of said signals at a time when said manual switch is not operated. BRIEF DESCRIPTION OF DRAWINGS The invention will be more readily understood from the following description of a preferred embodiment read In conjunction with the accompanying drawing of a schematic diagram of a controlling device constructed according to this invention. BEST MODE OF CARRYING OUT THE INVENTION It will be assumed that the controlling device shown in the drawing is one of a plurality of such devices disposed at convenient positions throughout a motion picture theatre about which is Installed a control buss of a ribbon cable of conventional form connected with control apparatus which is common to all of the controlling devices. This apparatus will have an earth buss, a power buss and a control buss of the ribbon cable connected with a summing amplifier and to seven x, y multipliers for amplitude control of sound being broadcast within the theatre. Each controlling device, as shown in the drawing, is preferably provided in a compact portable casing and utilises a conventional insulation displacement connector to permit the device to be electrically connected to the ribbon cable at any convenient position within the theatre, either upon installation of the control circuit, or even at the will of an operator. Each one of the controlling devices, as shown by the drawing, is terminated at points v, w, x, y and z on its connector and these terminals in turn will derive from the ribbon cable, respectively, RESET, STROBE, power, earth and ANALOGUE. It will also be noted that the entire logic of this circuit is derived from a single quad analogue gate 4016 and a single dual input quad NAND gate 4011. Both are Inexpensive, semi-conductor chips. Switch SWl is manually operable by the operator for selection of the respective controlling device. The switch SWl is preferably a press-button housing the LED which becomes illuminated upon selection of the device in order to identify the controlling device where control of the sound amplitude can be effected. When SWl is closed a "0" occurs at position (A) which is applied through the NAND gate Gl and appears as a "1" at point (B) which, being applied to the control gate of the analogue gate Al, induces base current flow in the transistor TR1 which then places the point (C) at ground potential so that a "0" is placed on the RESET buss of the ribbon cable. Preferably a parity check circuit is connected to the RESET buss to safeguard against false operation resulting from interference by extraneous signals. A parity circuit ideal for this purpose is described in co-pending application No. PG3552. As a result a "1" appears at the point (D) via the STROBE buss connected to terminal w. As a "1" now appears at both points (B) and (D), and therefore both inputs to the NAND gate G2, a "0" appears at point (E) to produce a "1" at point (F) which is latched on through the action of the flip-flop G3, G4. Analogue gate A2 thus permits transmission of an analogue control voltage determined at point (G) and under the control of the manually operable rheostat R4 to be applied via terminal z to the ANALOGUE buss. Hence, it will be seen that operation of switch SWl has caused Illumination of the LED and permitted transmission of a d.c. control voltage to a co mun summing amplifier and thence to x, y multipliers for amplitude control. The purpose of resistors Rl, R2 and R3, as well as transistor TR1, is for isolation purposes to protect the rather delicate semi-conductor devices against RF energy appearing on any buss. If now, control is desired from a different controlling device, and its switch SWl has been depressed, a "1" will appear on the common STROBE buss, and as switch SWl is open and a "1" is applied to the control gate of analogue gate A3, a signal is passed via analogue gate A4 to reset the flip-flop G3, G4, thereby unlatching the trigger on gate A2. Control of sound amplitude may then be effected Independently from the newly selected controlling device. It will be seen that under these circumstances where a "1" occurs at point (D) a "1" remains at point (E) as the Input to gate G2 which is connected to point (B) is presented with a "0". Whereas a single embodiment has been described in the foregoing passages, it should be understood that other forms. modifications and refinements are feasible within the scope of this invention.

Claims: 1. A control circuit for an electrical function and comprising a plurality of controlling devices connectable to a control buss of the circuit for said electrical function, and including a selection control circuit common to all of said controlling devices, each one of said controlling devices having a manual control for said function connectable via a semi-conductor switching device to said control buss, a switch manually operable for effecting by means of a signal from said selection control circuit activation of said switching device of a selected one of said controlling devices, and a trigger device effecting activation of said switching device when said trigger device is latched by operation of said manual switch and simultaneous receipt of said signal and becoming unlatched upon receipt of a subsequent one of said signals at a time when said manual switch Is not operated. 2. A control circuit as claimed in claim 1, wherein said trigger device is a flip-flop, and said selection control circuit is connected to a reset circuit for said flip-flop via a normally closed switch which is opened whenever said manual switch is operated. 3. a control circuit as claimed in claim 2. wherein said reset circuit switch is one element of a single quad analogue gate IC and another element thereof comprises said manual control. 4. A control circuit as claimed in claim 1, 2 or 3, wherein said control buss Includes a ribbon cable provided with at least five conductors, three of which are utilized for control of said function and two of which are connected with said selection circuit. 5. A control circuit as claimed in claim 2, wherein all of the active electronic components of each of said controlling devices are provided by a single quad analogue gate IC and a single dual input quad NAND gate IC. 6. A control circuit for an electrical function substantially as hereinbefore described with reference to the accompanying drawing.

Inventors: STOREY PHILLIP JAMES, STOREY, PHILLIP, JAMES
Applicants: GREATER UNION THEATRE SUPPLIES, STOREY PHILLIP JAMES, GREATER UNION THEATRE SUPPLIES PTY. LIMITED, STOREY, PHILLIP, JAMES
Application year: 1985
Main classification: G05B24
IPC codes: G05B24, H04Q9, H04R27