Voice switch circuits for use in loudspeaking telephone circuits

Claim 2

In a voice switch circuit for use in a loudspeaking telephone circuit of the class comprising a main comparator for comparing the signal level of a receiving circuit with the signal level of a transmitting circuit, a transmitting variable loss circuit responsive to a condition wherein the signal level of the receiving circuit is higher than the signal level of the transmitting circuit for inserting a loss in the transmitting circuit thereby establishing a receiving condition, and a receiving variable loss circuit responsive to a condition wherein the signal level of the transmitting circuit is higher than the signal Level of the receiving circuit for inserting a loss in the receiving circuit thereby establishing a transmitting condition, the improvement wherein said voice switch circuit comprises a control variable loss circuit inserted between said receiving circuit and said main comparator, a second comparator for comparing the output signal level from said control variable loss circuit with the signal level of said transmitting circuit, and means connected between said second comparator and said control variable loss circuit for operating said control variable loss circuit under the receiving condition for decreasing the level difference between two inputs of said main comparator.

Claim 3

In a voice switch circuit for use in a loudspeaking telephone circuit of the class comprising a main comparator for comparing the signal level of a receiving circuit with the signal level of a transmitting circuit, a transmitting variable loss circuit responsive to a condition wherein the signal level of the receiving circuit is higher than the signal level of the transmitting circuit for inserting a loss in the transmitting circuit thereby establishing a receiving condition, and a receiving variable loss circuit responsive to a condition wherein the signal level of the transmitting circuit is higher than the signal level of the receiving circuit for inserting a loss in the receiving circuit thereby establishing a transmitting condition, the improvement wherein said voice switch circuit comprises a first control variable loss circuit inserted between said receiving circuit and said main comparator, a second control variable loss circuit inserted between said transmitting circuit and said main comparator, first and second comparators for comparing the level of the output signal from said first control variable loss circuit with the level of the output signal from said second control variable loss circuit, first means connected between said first comparator and said first control variable loss circuit for maintaining the loss in said first control variable loss circuit under the receiving condition, and second means connected between said second comparator and said second control variable loss circuit for maintaining the loss in said second control variable loss circuit under the transmitting condition.

Claim 4

In a voice switch circuit for use in a loudspeaking telephone circuit of the class comprising a main comparator for comparing the signal level of a receiving circuit with the signal level of a transmitting circuit, a transmitting variable loss circuit responsive to a condition wherein the signal level of the receiving circuit is higher than the signal level of the transmitting circuit for inserting a loss in the transmitting circuit thereby establishing a receiving condition, and a receiving variable loss circuit responsive to a condition wherein the signal level of the transmitting circuit is higher than the signal level of the receiving circuit for inserting a loss in the receiving circuit thereby establishing a transmitting condition, the improvement wherein said voice switch circuit comprises a first control variable loss circuit inserted between said receiving circuit and said main comparator, a second control variable loss circuit inserted between said transmitting circuit and said main comparator, first and second comparators for comparing the level of the output signal from said first control variable loss circuit with the level of the output signal from said second control variable loss circuit, first means connected between said first comparator and said first control variable loss circuit for maintaining the loss in said first control variable loss circuit under the receiving condition, and second means connected between said second comparator and said second control variable loss circuit for maintaining the loss in said second control variable loss circuit under the transmitting condition.

Claim 5

The voice switch circuit according to claim 2 wherein said first means comprises a first memory device that memorizes the level of the output from said first comparator under the receiving condition.

Claim 6

The voice switch circuit according to claim 2 wherein said second means comprises a second memory device that memorizes the level of the output from said second comparator under the transmitting condition.

Claim 7

The voice switch circuit according to claim 3 which further comprises first reset means which reset the content of said first memory device when the circuit is switched to the transmitting condition.

Claim 8

The voice switch circuit according to claim 4 which further comprises second reset means for resetting the content of said second memory device when the circuit is switched to the receiving condition.

Claim 9

The voice switch circuit according to claim 4 which further includes circuit means for increasing the gain of said main comparator in accordance with the output level from said second memory device under the transmitting condition.

Claim 10

In a voice switch circuit for use in a loudspeaking telephone circuit of the type comprising a main comparator for comparing the signal level of a receiving circuit with the signal level of a transmitting circuit, a transmitting variable loss circuit responsive to a condition wherein the signal level of the receiving circuit is higher than the signal level of the transmitting circuit for inserting a loss in the transmitting circuit thereby establishing a receiving condition, and a receiving variable loss circuit responsive to a condition wherein the signal level of the transmitting circuit is higher than the signal level of the receiving circuit for Inserting a loss in the receiving circuit thereby establishing a transmitting condition, the improvement wherein said voice switch circuit comprises a control variable amplifier circuit inserted between said transmitting circuit and said main comparator, a second comparator for comparing the output level of said control variable amplifier circuit with the signal level of said receiving circuit, and means connected between said second comparator and said control variable amplifier circuit for operating said control variable amplifier circuit under the receiving condition for minimizing the difference in the level of two inputs to said main comparator.

Claim 11

In a voice switch circuit for use in a loudspeaking telephone circuit of the type comprising a main comparator for comparing the signal level of a receiving circuit with the signal level of a transmitting circuit, a transmitting variable loss circuit responsive to a condition wherein the signal level of the receiving circuit is higher than the signal level of the transmitting circuit for inserting a loss in the transmitting circuit thereby establishing a receiving condition, and a receiving variable loss circuit responsive to a condition wherein the signal level of the transmitting circuit is higher than the signal level of the receiving circuit for Inserting a loss in the receiving circuit thereby establishing a transmitting condition, the improvement wherein said voice switch circuit comprises a control variable amplifier circuit inserted between said transmitting circuit and said main comparator, a second comparator for comparing the output level of said control variable amplifier circuit with the signal level of said receiving circuit, and means connected between said second comparator and said control variable amplifier circuit for operating said control variable amplifier circuit under the receiving condition for minimizing the difference in the level of two inputs to said main comparator.

Claim 12

In a voice switch circuit for use in a loudspeaking telephone circuit of the type comprising a main comparator for comparing the signal level of a receiving circuit with the signal level of a transmitting circuit, a transmitting variable loss circuit responsive to a condition wherein the signal level of the receiving circuit is higher than the signal level of the transmitting circuit for inserting a loss in the transmitting circuit thereby establishing a receiving condition, and a receiving variable loss circuit responsive to a condition wherein the signal level of the transmitting is higher than the signal level of the receiving circuit for inserting a loss in the receiving circuit thereby establishing a transmitting condition, the improvement wherein said voice switch circuit comprises a first control variable amplifier circuit inserted between said receiving circuit and said main comparator, a second control variable amplifier circuit inserted between said transmitting circuit and said main comparator, first and second comparators for comparing the output signal level of said first control variable amplifier circuit with the output signal level of said second control variable amplifier circuit, second means connected between said second comparator and said second control variable amplifier circuit for maintaining the gain of said second control variable amplifier circuit under the receiving condition, and first means connected between said first comparator and said first control variable amplifier circuit for maintaining the gain of said first control variable amplifier circuit under the transmitting condition.

Claim 13

In a voice switch circuit for use in a loudspeaking telephone circuit of the type comprising a main comparator for comparing the signal level of a receiving circuit with the signal level of a transmitting circuit, a transmitting variable loss circuit responsive to a condition wherein the signal level of the receiving circuit is higher than the signal level of the transmitting circuit for inserting a loss in the transmitting circuit thereby establishing a receiving condition, and a receiving variable loss circuit responsive to a condition wherein the signal level of the transmitting is higher than the signal level of the receiving circuit for inserting a loss in the receiving circuit thereby establishing a transmitting condition, the improvement wherein said voice switch circuit comprises a first control variable amplifier circuit inserted between said receiving circuit and said main comparator, a second control variable amplifier circuit inserted between said transmitting circuit and said main comparator, first and second comparators for comparing the output signal level of said first control variable amplifier circuit with the output signal level of said second control variable amplifier circuit, second means connected between said second comparator and said second control variable amplifier circuit for maintaining the gain of said second control variable amplifier circuit under the receiving condition, and first means connected between said first comparator and said first control variable amplifier circuit for maintaining the gain of said first control variable amplifier circuit under the transmitting condition.

Claim 14

The voice switch circuit according to claim 9 wherein said first means comprises a first memory device for memorizing the output level of said first comparator under the transmitting condition, and said second means comprises a second memory device for memorizing the output level of said second comparator under the receiving condition.

Claim 15

The voice switch circuit according to claim 10 which further comprises first reset means for resetting the content of said first memory device when the circuit is switched to the receiving condition.

Claim 16

The voice switch circuit according to claim 10 which further comprises second reset means for resetting the content of said second memory device when the circuit is switched to the transmitting condition.

Claim 17

The voice switch circuit according to claim 9 which further comprises circuit means for increasing the gain of the main comparator in accordance with the output level of said first memory device under the transmitting condition.

Claim 18

In a voice switch circuit for use in a loudspeaking telephone circuit of the type comprising a main comparator for comparing the signal level of a receiving circuit with the signal level of a transmitting circuit, a transmitting variable loss circuit responsive to a condition wherein the signal level of the receiving circuit is higher than the signal level of the transmitting circuit for inserting a loss in said transmitting circuit thereby establishing a receiving condition, and a receiving variable loss circuit responsive to a condition wherein the signal level of the transmitting circuit is higher than the signal level of the receiving circuit for inserting a loss in said receiving circuit thereby establishing a transmittiNg condition, the improvement wherein said voice switch circuit comprises a first control variable loss circuit inserted between said receiving circuit and said main comparator, a second control variable loss circuit inserted between said transmitting circuit and said main comparator, first and second comparators for comparing the output signal level of said first control variable loss circuit with the output signal level of said second control variable loss circuit, a first memory device connected between said first comparator and said first control variable loss circuit for memorizing the output level of said first comparator for maintaining the loss in said first control variable loss circuit only under the receiving condition, a second memory device connected between said second comparator and said second control variable loss circuit for memorizing the output level of said second comparator for maintaining the loss in said second control variable loss circuit only under the transmitting condition, first reset means for resetting the content of said first memory device when the circuit is switched to the transmitting condition, second reset means for resetting the content of said second memory device when the circuit is switched to the receiving condition, and circuit means for increasing the gain of said main comparator in accordance with the output level of said second memory device during the transmitting condition.

Claim 19

In a voice switch circuit for use in a loudspeaking telephone circuit of the type comprising a main comparator for comparing the signal level of a receiving circuit with the signal level of a transmitting circuit, a transmitting variable loss circuit responsive to a condition wherein the signal level of the receiving circuit is higher than the signal level of the transmitting circuit for inserting a loss in said transmitting circuit thereby establishing a receiving condition, and a receiving variable loss circuit responsive to a condition wherein the signal level of the transmitting circuit is higher than the signal level of the receiving circuit for inserting a loss in said receiving circuit thereby establishing a transmittiNg condition, the improvement wherein said voice switch circuit comprises a first control variable loss circuit inserted between said receiving circuit and said main comparator, a second control variable loss circuit inserted between said transmitting circuit and said main comparator, first and second comparators for comparing the output signal level of said first control variable loss circuit with the output signal level of said second control variable loss circuit, a first memory device connected between said first comparator and said first control variable loss circuit for memorizing the output level of said first comparator for maintaining the loss in said first control variable loss circuit only under the receiving condition, a second memory device connected between said second comparator and said second control variable loss circuit for memorizing the output level of said second comparator for maintaining the loss in said second control variable loss circuit only under the transmitting condition, first reset means for resetting the content of said first memory device when the circuit is switched to the transmitting condition, second reset means for resetting the content of said second memory device when the circuit is switched to the receiving condition, and circuit means for increasing the gain of said main comparator in accordance with the output level of said second memory device during the transmitting condition.

Claim 20

The voice switch circuit according to claim 10 which further comprises first reset means for resetting the content of said first memeory device when the circuit is switched to the receiving condition and second reset means for resetting the content of said second memory device when the circuit is switched to the transmitting condition.