JPH04103782U - Color burst signal continuation circuit - Google Patents

Abstract

(57) [Summary] [Purpose] Convert intermittently generated reproduction burst signals into continuous signals and use them for jitter correction. [Structure] During the burst signal generation period, the burst signal and the output of the analog delay circuit 13 are compared to control the delay amount of the analog delay circuit 13, and during the burst signal deactivation period, the output of the analog delay circuit 13 is transferred to the phase shift circuit. By comparing the phase-advanced output at step 14 with the output of the analog delay circuit 13 and controlling the delay amount of the analog delay circuit 13, a burst signal is continuously generated.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

The present invention is an improvement to a color burst signal continuation circuit that is effective for use in jitter correction circuits. Regarding good.

0002

[Conventional technology]

The applicant has disclosed a color burst signal continuous circuit in Japanese Patent Application Laid-Open No. 1-69189. suggested a route.

0003 This continuous circuit outputs the reproduction color burst signal and the 1/4 frequency division of the oscillation circuit output. The phase comparison circuit compares the phase of the In the circuit, a delay circuit such as a CCD that uses the oscillation output as the clock input is installed, and the reproduction circuit is The output of this delay circuit is supplied to the phase comparator circuit during the period when the error burst signal is inactive. The key point is to make phase control continuous.

0004

[Problem that the idea aims to solve]

However, the conventional circuit described above has a structure that controls the oscillation circuit according to the detected phase difference. and poor responsiveness.

[0005] Therefore, the present invention has developed a color filter that quickly follows reproduced color burst signals with high precision. The purpose of this paper is to propose a burst signal continuation circuit.

[0006]

[Means to solve the problem]

The present invention consists of a phase shift circuit that generates a phase-shifted output by shifting the phase of a continuous signal by a predetermined amount, and a burst gate by selecting the reproduced color burst signal during the generation period of the gate pulse. a switching circuit that selects the phase-shifted output during a pulse extinction period; Phase comparison using the output of the switching circuit as the reference input and the continuous signal fed back as the comparison input circuit, and the delay amount of the output of the switching circuit based on the output of the phase comparison circuit. A color burst signal link with an analog delay circuit that controls and generates a continuous signal. The jitter correction circuit is characterized in that a continuation circuit is provided in the jitter correction circuit.

[0007]

[Effect]

Therefore, according to the present invention, the reproduced color bar is not activated during the burst gate pulse de-energization period. The burst signal also outputs a phase-shifted output of the analog delay circuit during the burst gate pulse generation period. Each power is constantly supplied to the analog delay circuit without interruption.

[0008]

【Example】

The present invention will be described below with reference to illustrative embodiments.

[0009] First, Figure 1 shows how the color bar of this invention is applied to the color frequency conversion circuit on the playback side of a VTR. 1 is a circuit block diagram of a first embodiment that employs a strike signal serialization circuit.

0010 As is clear from this figure, first, the playback output of the low frequency conversion color signal is output from the ACC circuit. 1, the signal level is made constant and supplied to the first frequency conversion circuit 2.

[0011] The first frequency conversion circuit 2 converts the reproduced low frequency conversion color signal into a frequency conversion carrier. NTSC modulation color through the first band pass filter 3 in the next stage. – The signal is separated and derived.

0012 This frequency conversion carrier is used as a fixed reference oscillator in the second frequency conversion circuit 4. NTSC color subcarrier component generated by 5 and the low frequency component generated by VCO6. and the subcarrier component, and input it to the second bandpass filter 7. formed by

[0013] This VCO 6 is a modulated color signal derived from the second bandpass filter 3. In order to keep the carrier frequency of the signal constant, the oscillation frequency is converted to a reproduced low-frequency conversion color signal. This allows the signal to follow the carrier frequency fluctuations of the signal.

[0014] Therefore, the output of the color burst signal continuation circuit according to the present invention and the reference color sample are The phase of the carrier component is compared in the APC detection circuit 8, and the comparison output is a low-frequency signal. The signal is supplied to the control input terminal of the VCO 6 via the filter 9.

[0015] The operation of the color burst signal continuation circuit, which is a feature of this invention, is explained below. do.

[0016] First, the modulated color signal derived from the first bandpass filter 3 is It is used as a signal input to the switching circuit 9.

[0017] This switching circuit 9 uses a burst gate pulse as a control input, and The burst signal in the modulated color signal is selected during the generation period of the burst gate pulse, and the burst signal is erased. The phase-shifted output that returned during the current period is selected.

[0018] The switching output is supplied to the analog delay circuit 13 and is simultaneously supplied to the phase comparison circuit. 11 is also supplied.

[0019] The analog delay circuit 13 delays the input signal by 90 degrees regardless of frequency fluctuations. The phase comparator circuit 11 calculates the delay output based on the switching output. Generates a phase comparison output according to the amount of delay, and passes the phase comparison output to the second low-pass filter. 12.

[0020] This low-pass output is supplied as a control input to the analog delay circuit 13. In this embodiment, a delay is applied to derive a delayed output even during the deactivation period of the burst gate pulse. The phase shifter 14 advances the extended output by 90 degrees, and the advanced output is input to the switching circuit 9 and other inputs. He is returning as a force.

[0021] Therefore, the switching output is always connected to the analog delay circuit 13 and the phase comparison The burst signal is supplied to the circuit 11 and is made continuous without interruption.

[0022] Therefore, the control signal is always supplied to the VCO 9, and the jitter component is detected with high accuracy. oppressed.

[0023] Figure 2 shows the burst signal serialization circuit of the present invention installed in an optical video disc player. A circuit block diagram of the adopted second embodiment is shown.

[0024] As is clear from this figure, the video disc player of this embodiment has a pickup. After demodulating the playback output of the amplifier 15 in the next stage FM demodulation circuit 16, the output is jittered in the CCD 17. The burst signal continuation circuit of this invention is used for this jitter correction. It is.

[0025] In this embodiment, the output of the burst signal serialization circuit is used as the comparison input, and the output of the reference oscillator 5 is used as the comparison input. Using the power as a reference input, the APC detection circuit 8 performs phase detection.

[0026] The phase detection output is separated into low frequency components by the first low-pass filter 9, and then sent to the VCO. 6 as an oscillation control voltage.

[0027] The center frequency of this VCO is set to four times that of the color subcarrier, and jitter is reduced. The oscillation frequency is changed accordingly.

[0028] This oscillation output is supplied as a transfer clock to the CCD 17. As a result, a jitter-corrected reproduced color video signal is introduced from the CCD 17. Served.

[0029]

[Effect of the idea]

Therefore, according to the present invention, in order to make the burst signal continuous using an analog delay circuit, This not only makes it possible to perform accurate jitter correction, but also makes it possible to miniaturize the circuit, increasing its effectiveness. The fruit is big.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram of a first embodiment.

FIG. 2 is a circuit block diagram of a second embodiment.

[Explanation of symbols]

10 Switching circuit 11 Phase comparator circuit 13 Analog delay circuit 14 Phase shifter

Claims (2)

[Scope of utility model registration request] 1. A jitter correction circuit that corrects jitter components by controlling the delay time of the reproduced color video signal in synchronization with the multiplied output of a continuous signal obtained by continuousizing a color burst signal in the reproduced color video signal. a phase shift circuit that shifts the phase of the continuous signal by a predetermined amount to generate a phase-shifted output; and a phase shift circuit that selects a reproduced color burst signal during a period in which a burst gate pulse is generated, and shifts the phase during a period when the burst gate pulse is inactive. a switching circuit that selects an output, a phase comparison circuit that uses the output of the switching circuit as a reference input and the fed back continuous signal as a comparison input, and calculates the amount of delay in the output of the switching circuit based on the output of the phase comparison circuit. A color burst signal continuation circuit consisting of an analog delay circuit that controls and generates a continuous signal. 2. In order to frequency-convert the reproduced output of the low-pass converted color signal using a frequency conversion carrier, a continuous signal obtained by converting the frequency-converted color burst signal and a reference signal are compared in phase, and the frequency conversion carrier is The jitter correction circuit that generates the output includes a phase shift circuit that shifts the phase of the continuous signal by a predetermined amount to generate a phase-shifted output, and a phase shift circuit that selects a reproduced color burst signal during the burst gate pulse generation period, and selects a reproduced color burst signal during the burst gate pulse generation period. a switching circuit that selects the phase-shifted output during the de-energization period; a phase comparison circuit that uses the output of the switching circuit as a reference input and uses the fed-back continuous signal as a comparison input; A color burst signal continuation circuit consisting of an analog delay circuit that controls the delay amount of the output of the circuit and generates a continuous signal.