Drive-in theater audio system

Claim 3

The system of claim 1 wherein the impedance matching means comprises a plurality of passive components.

Claim 4

The system of claim 1 wherein said coupling network further comprises: a first resistor connected between one conductor of an audio wiring circuit and a first lead-in wire, and a second resistor connected between the other conductor of an audio wiring circuit and a second lead-in wire.

Claim 5

The system of claim 1 wherein the termination means further comprises: a resistor connected in parallel with the end of each wiring circuit.

Claim 6

The system of claim 1 wherein the lead-in wire further comprises: a capacitively coupled elongated flexible conductor.

Claim 7

The system of claim 1 which further includes: power level adjuster means for adjusting the power level associated with each audio wiring circuit.

Claim 8

In a drive-in movie theater having a plurality of rows of automobile parking spaces, each row equipped with an existing unshielded audio wiring circuit normally utilized to carry audio frequency signals to speaker locations at each parking space, an improvement comprising: a sound-type motion picture projector; radio frequency transmitter means connected to the audio output of the projector for providing radio frequency output signals containing the audio portion of the movie; power divider means having an input coupled to said transmitter means and a plurality of outputs; a plurality of shielded conductors coupled to the outputs from the power divider; impedance matching means for coupling each of said audio wiring circuits to one of the shielded conductors from the power divider, operative to match the impedance of the power dividing means to the impedance of the audio wiring circuits to which it is connected; a plurality of lead-in wires operative for connection at one end to a separate automobile radio receiver connection; a plurality of coupling networks along spaced points of each audio wiring circuits located near the parking spaces, operative for connecting the other end of said lead-in wires to the audio wiring circuits; and termination means coupled to the ends of each audio wiring circuit having an impedance equal to the impedance thereof whereby said drive-in theater may be economically converted to a radio frequency system for efficiently transmitting the audio portions of the movie by using existing unshielded audio wiring circuits.

Claim 9

In a drive-in movie theater having a plurality of rows of automobile parking spaces, each row equipped with an existing unshielded audio wiring circuit normally utilized to carry audio frequency signals to speaker locations at each parking space, an improvement comprising: a sound-type motion picture projector; radio frequency transmitter means connected to the audio output of the projector for providing radio frequency output signals containing the audio portion of the movie; power divider means having an input coupled to said transmitter means and a plurality of outputs; a plurality of shielded conductors coupled to the outputs from the power divider; impedance matching means for coupling each of said audio wiring circuits to one of the shielded conductors from the power divider, operative to match the impedance of the power dividing means to the impedance of the audio wiring circuits to which it is connected; a plurality of lead-in wires operative for connection at one end to a separate automobile radio receiver connection; a plurality of coupling networks along spaced points of each audio wiring circuits located near the parking spaces, operative for connecting the other end of said lead-in wires to the audio wiring circuits; and termination means coupled to the ends of each audio wiring circuit having an impedance equal to the impedance thereof whereby said drive-in theater may be economically converted to a radio frequency system for efficiently transmitting the audio portions of the movie by using existing unshielded audio wiring circuits.

Claim 10

The improvement of claim 7 wherein said audio wiring circuits are coupled to their respective shielded conductor from said power divider means at substantially the center of each audio wiring circuit.

Claim 11

The improvement of claim 8 which further comprises: a second power divider means having its input coupled to an output of the first power divider means, and two outputs, each output coupled to the inner ends of its associated audio wiring circuit.

Claim 12

The improvement of claim 9 wherein said impedance matching means comprises a first impedance matching network coupled between one output of said second power divider and one inner end of its associated audio wiring circuit portion, and a second impedance matching network coupled to the other output of said second power divider and the other inner end of its associated audio wiring circuit portion.

Claim 13

The improvement of claim 10 wherein said termination means further comprises: a first termination network coupled to one outer end of its associated audio wiring circuit portion, and a second termination network coupled to the other outer end of its associated audio wiring circuit portion, each network having an impedance equal to the impedance of each audio wiring circuit portion to which it is connected.

Claim 14

The improvement of claim 11 wherein said first and second termination networks are located at opposite ends of one row of parking spaces in posts which formally held speakers.

Claim 15

The improvement of claim 12 which further comprises power level adjuster means for adjusting the amount of power transmitted to each wiring circuit associated with each row in the theater.

Claim 18

The method of claim 14 wherein the nonshielded audio wiring circuits are terminated by placing the characteristic impedance in speaker posts at the ends of the rows in the theater.

Claim 19

The method of claim 14 wherein the shielded conductors are coupled to central portions of the audio wiring circuits through a power divider.

Claim 20

The method of claim 16 wherein inner portions of each audio wiring circuit are coupled to the power divider through separate impedance matching networks.

Claim 21

The method of claim 17 wherein the outer portions of each audio wiring circuit are terminated by characteristic impedances located in the speaker posts at the ends of the rows in the theater.

Claim 22

The method of claim 14 which further comprises selectively adjusting the power level to each of the audio wiring circuits depending upon the transmission characteristics of each circuit.

Claim 23

The method of claim 14 wherein the audio wiring circuits are tapped by coupling networks installed in a drive-in theater post which formerly held a speaker.