Video signal delay circuit having self adjusting gain

Claim 2

A video signal delay circuit comprising: a first circuit for fixing a pedestal level of a video signal to a predetermined level; an inserting circuit for inserting a pulse signal in a signal period of the video signal partially corresponding to a blanking period thereof, the pulse signal having a predetermined level with respect to the pedestal level; a delay element for receiving the video signal in which the pulse signal is inserted by said inserting circuit, and for delaying the video signal by a predetermined period of time; a variable gain amplifier for receiving an output signal from said semiconductor delay element, and for amplifying the output signal to generate an amplified signal having a pulse corresponding to the pulse inserted by the inserting circuit; and a gain control circuit, responsive to the amplified signal, for controlling the gain of said variable gain amplifier such that the pulse in the amplified signal is set at a predetermined level with respect to the pedestal level.

Claim 3

A video signal delay circuit according to claim 1, wherein said inserting circuit comprises a reference power source and switching means for switchin between said reference power source and the video signal during the blanking period of the video signal.

Claim 4

A video signal delay circuit according to claim 1, wherein said inserting circuit comprises a pulse generator for generating a pulse signal corresponding to the blanking period of the video signal, and adding means for adding the pulse signal in a signal period of the video signal.

Claim 5

A video signal delay circuit according to claim 1, where said delay element comprises a charge-coupled device.

Claim 6

A video signal delay circuit according to claim 1, wherein said gain control cirucit comprises a differential amplifier for obtaining a difference voltage between an output voltage of said variable gain amplifier and a reference voltage, a switching circuit for extracting the difference voltage in correspondence with the pulse signal inserted in the video signal, and a holding circuit for supplying the difference voltage, extracted through said switching circuit, to said variable gain amplifier as a control signal.

Claim 7

A video signal delay circuit according to claim 1, wherein said inserting circuit comprises a reference power source; and switching means for switching between said reference power source and the video signal during the blanking period of the video signal, and said gain control circuit comprises a differential amplifier for obtaining a difference voltage of an output voltage from said variable gain amplifier and a reference voltage supplied from said reference power source, a switching circuit for extracting the difference voltage in correspondence with the pulse signal inserted in the video signal, and a holding circuit for supplying the difference voltage, extracted through said switching circuitt, to said variable gain amplifier as a control signal.

Claim 8

A video signal delay circuit according to claim 1, wherein said inserting circuit comprises a pulse generator for generating a pulse signal corresponding to the blanking period of the video signal; and adding means for adding the pulse signal generated by said pulse generator in the blanking period of the video signal, and said gain control circuit comprises a differential amplifier for obtaining a difference voltage between an output voltage of said variable gain amplifier and the pulse signal supplied from said pulse generator; a switching circuit for extracting the difference voltage in correspondence with the pulse signal inserted in the video signal; and a holding circuit for supplyin the difference voltage, extracted through said switching circuit, to said variable gain amplifier as a control signal.

Claim 9

A circuit for delaying a video signal having a pedestal level comprising: an inserting circuit for inserting a pulse into the video signal during a blanking period of the video signal the inserting circuit including a reference power source, and switching means for switching between the reference power source and the video signal during the blanking period of the video signal; a delay element for receiving the video signal in which the pulse signal is inserted by the inserting circuit, and for delaying the video signal by a predetermined period of time; a variable gain amplifier for receiving an output signal from the semiconductor delay element, and for amplifying the output signal to generate an amplified signal having a pulse corresponding to the pulse inserted by the inserting circuit; and a gain control circuit, responsive to the amplifier signal, for controlling the gain of the variable gain amplifier such that the pulse in the amplified signal is set at a predetermined level with respect to the pedestal level, the gain control circuit including a differential amplifier for obtaining a difference voltage of an output voltage from the ariable gain amplifier and a reference voltage supplied from the reference power source, a switching circuit for extracting the difference votlage in correspondence with the pulse signal inserted in the video signal, and a holding circuit for supplying the difference voltage, exracted through the switching circuit, to the variable gain amplifier as a control signal.

Claim 10

A circuit for delaying a video signal having a pedestal level comprising: an inserting circuit for inserting a pulse into the video signal during a blanking period of the video signal the inserting circuit including a reference power source, and switching means for switching between the reference power source and the video signal during the blanking period of the video signal; a delay element for receiving the video signal in which the pulse signal is inserted by the inserting circuit, and for delaying the video signal by a predetermined period of time; a variable gain amplifier for receiving an output signal from the semiconductor delay element, and for amplifying the output signal to generate an amplified signal having a pulse corresponding to the pulse inserted by the inserting circuit; and a gain control circuit, responsive to the amplifier signal, for controlling the gain of the variable gain amplifier such that the pulse in the amplified signal is set at a predetermined level with respect to the pedestal level, the gain control circuit including a differential amplifier for obtaining a difference voltage of an output voltage from the ariable gain amplifier and a reference voltage supplied from the reference power source, a switching circuit for extracting the difference votlage in correspondence with the pulse signal inserted in the video signal, and a holding circuit for supplying the difference voltage, exracted through the switching circuit, to the variable gain amplifier as a control signal.

Claim 11

A circuit for delaying a video signal having a pedestal level comprising: an inserting circuit for inserting a pulse into the video signal during a blanking period of the video signal, the inserting circuit including a pulse generator for generating a pulse signal corresponding to the blanking period of the video signal, and adding means for adding the pulse signal generated by the pulse generator in the blanking period of the video signal; a delay element for receiving the video signal in which the pulse signal is inserted by the inserting circuit, and for delaying the video signal by a predetermined period of time; a variable gain amplifier for receiving an output signal from the semiconductor delay element, and for amplifying the output signal to generate an amplified signal having a pulse corresponding to the pulse inserted by the inserting circuit; and a gain control circuit, responsive to the amplified signal, for controlling the gain of the variable gain amplifier such that the pulse in the amplified signal is set at a predetermined level with respect to the pedestal level, the gain control circuit including a differential amplifier for obtaining a difference voltage between an output voltage of the variable gain amplifier and the pulse signal suuplied from the pulse generator, a switching circuit for extracting the difference voltage in correspondence witht he pulse signal inserted in the video signal, and a holding circuit for supplying the difference voltage, extracted through the siwtching circuit, to the variable gain amplifier as a control signal.

Claim 12

A circuit for delaying a video signal having a pedestal level comprising: an inserting circuit for inserting a pulse into the video signal during a blanking period of the video signal, the inserting circuit including a pulse generator for generating a pulse signal corresponding to the blanking period of the video signal, and adding means for adding the pulse signal generated by the pulse generator in the blanking period of the video signal; a delay element for receiving the video signal in which the pulse signal is inserted by the inserting circuit, and for delaying the video signal by a predetermined period of time; a variable gain amplifier for receiving an output signal from the semiconductor delay element, and for amplifying the output signal to generate an amplified signal having a pulse corresponding to the pulse inserted by the inserting circuit; and a gain control circuit, responsive to the amplified signal, for controlling the gain of the variable gain amplifier such that the pulse in the amplified signal is set at a predetermined level with respect to the pedestal level, the gain control circuit including a differential amplifier for obtaining a difference voltage between an output voltage of the variable gain amplifier and the pulse signal suuplied from the pulse generator, a switching circuit for extracting the difference voltage in correspondence witht he pulse signal inserted in the video signal, and a holding circuit for supplying the difference voltage, extracted through the siwtching circuit, to the variable gain amplifier as a control signal.

Claim 13

A circuit adapted for receiving a first signal having a blanking period comprising: first means for generating a second signal by inserting a pulse into the first signal during the blanking period; second means for generating a third signal by delaying the second signal; third means, having a control input, for generating a fourth signal by amplifying the third signal with a gain determined by a signal on the control input; and fourth means, responsive to the fourth signal, for generating a fifth signal and for sending the fifth signal to the control input in synchronism with inserting of the pulse by the first means.

Claim 14

A circuit adapted for receiving a first signal having a blanking period comprising: first means for generating a second signal by inserting a pulse into the first signal during the blanking period; second means for generating a third signal by delaying the second signal; third means, having a control input, for generating a fourth signal by amplifying the third signal with a gain determined by a signal on the control input; and fourth means, responsive to the fourth signal, for generating a fifth signal and for sending the fifth signal to the control input in synchronism with inserting of the pulse by the first means.

Claim 15

A circuit according to claim 10, wherein the first means includes a reference voltage source; and means for switching between the reference voltage source and the first signal.

Claim 16

A circuit according to claim 10, wherein the first means includes means for adding the pulse to the first signal.

Claim 17

A circuit according to claim 10, wherein the second means includes a charge-coupled device.

Claim 18

A circuit according to claim 10, wherein the fourth means includes means for obtaining a difference voltage between the fourth signal and a reference voltage; and a holding circuit for supplying the difference voltage to the control input.