JPS62133890A - Simple type time base correcting device - Google Patents

Abstract

PURPOSE:To facilitate the integration of a circuit by controlling video signals in the state of FM signals and taking time base variation and thereby constituting the circuits of a time base correcting device only with analog circuits. CONSTITUTION:Luminance signal component made to the low carrier FM signal of video signals reproduced by the HPF 11 of the time base correcting device is extracted, and the low band converted chrominance signals of video signals are extracted by an LPF 12. The luminance signal component is processed by a limiter 13 and applied to an analog signal control type variable delay circuit 14. Color difference signals are processed by an FM modulator 19 and a limiter 20 and applied to an analog signal control type variable delay circuit 21. The output of the circuit 14 is applied to a phase detector 17 through a demodulator 15 and a synchronizing signal separating circuit 16, and phase difference from a reference synchronizing signal HD is detected. The detection signal is applied to circuits 14, 21 through an LPF 18 and respective delay time is controlled. Luminance and color difference signals from demodulators 15, 22 are composed by a composing circuit 24, and composite video signals having no jitter component are outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention provides a method for compensating for time axis fluctuations in a +lr raw video signal.
: This relates to a simple time axis correction device that can perform the following functions.

[Summary of the invention]

The Tsutsuyoshi time base correction device of the present invention separates a reproduced video signal into a low carrier FM signal and a low frequency conversion color signal, and then manually inputs the low carrier FM signal to a first analog signal controlled variable delay circuit. The low frequency conversion color signal is converted into an FM signal and then input to a second analog signal control type +i-modulated delay circuit for demodulation. Then, based on the phase difference information between the synchronization signal of the demodulated luminance signal and the reference synchronization signal, 1j. Second analog signal control type r+■
The variable delay circuit 'II Ensei is controlled to obtain a video playback signal free of jitter components.

[Conventional technology]

Magnetic recording LF recording equipment (VTR) using a rotating head is often used as a device for recording and reproducing video signals. It is common for the time axis of the reproduced video signal to vary.

For this reason, high-grade VTR models are equipped with a time base correction device (TBC) to remove +Ir raw video signal 0 time base fluctuations (zinc).

FIG. 3 is a diagram showing an example of such an IIv axis interpolation device, in which the playback video signal inputted from the end fT is input to the A/D converter l, and the input signal from the write clock signal generator 4 is input to the A/D converter l. The data is converted into a digital value by , and further written into the memory 2 controlled by the address signal generated by the read-in address signal generator 5 .

The video signal clocked into the memory 2 is read out from the memory 2 by a read address signal generator 7 formed from a standard clock signal -tCLK and further clocked by a read clock signal generator 8. The A converter 3 converts it into an analog signal and outputs it.

Note that 6 is t: a memory control circuit that controls the timing of reading and writing.

Such a time axis correction device has a 111-t interval fluctuation in the read address (,) of the memory 2 (1).
Since it is formed from the synchronization of the raw video signal (-), the time axis fluctuation (error) is canceled out in the input state y island to memory 2, and this is used as the stable reference Cronk signal. By reading out the video signal, a video signal from which the axis error between 111j and 111j has been removed can be obtained.

[Problem that the invention seeks to solve]

However, this time axis correction device converts the analog signal to -[1-
In order to convert to a digital signal and then convert it back to an analog signal, a high-speed A/D converter and a D/A converter are required, as well as a digital memory, a clock signal generator, etc. Therefore, there is a problem in that the device is expensive and is not suitable for sweat-type consumer products.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a simple time axis correction device that can easily remove the time axis fluctuation error of the video signal t5 in the state of an analog signal.

[L stage for solving problems]

The first type has a delay time controlled by an analog voltage or current value. The second analog control type (1'f change'I
The phase difference between the synchronization signal extracted from the demodulated luminance signal and the synchronization signal of the bezel is According to the detected signal, the first. Second analog control type II
The system is configured to control detours.

[Effect]

The luminance signal component of the video signal reproduced from a VTR or the like has jitter components removed by the first analog signal control type i+r variable delay circuit, and the low frequency converted color signal component is frequency modulated. Afterwards, the second analog signal-controlled delay circuit is manually inputted to the first analog signal-controlled ri in +in.
The jitter component is removed by the control signal of the f variable delay circuit. Therefore, a detour such as changing the two + by 1 is required, but the recording and reproducing method uses a low-frequency conversion chromaticity V that has good chroma convergence regardless of luminance or chromatic jitter. It has the advantage of being able to take advantage of its features.

〔Example〕

FIG. 1 shows a block diagram of a simple time base correction device showing an embodiment of the present invention, and reference numeral 11 indicates an FIL which is said to be a low carrier FM signal from an iq generated video signal.
Bypass filter that outputs the signal component, 12 is a turn.
]1f This is a low-pass filter that extracts the low-pass-converted color signal of the generated video signal.

To explain the luminance signal system, 13 is a limiter, 14
is the first analog signal controlled delay circuit (hereinafter referred to as the first I'Tf delay circuit), and as described later, a gate circuit or a logic element such as an inverter can be used. 15 is a demodulator, 16 is a synchronization disease-) (water mode) separation circuit, and 17 is a phase of the separated synchronization signal) and base (of the synchronization signal -Reff (wood f), which detects the phase p. It is a detector.

Next, to explain the color signal system, numeral 19 is a frequency converter for converting to a low frequency converted color light FM 4, -;, numeral 20 is a limiter, and numeral 21 is a second analog signal controlled variable A control signal for the first detour path 14 and the second detour path (hereinafter referred to as the second detour path) is supplied via a low-pass filter 18. 22 is a demodulator, 23 is a frequency converter for converting the demodulated low-frequency color light into a carrier color (1.1-), 2
4 is a synthesis circuit.

1) The crystal type time axis correction device of the present invention has the configuration as described above, so that when a raw video with turbulence is input manually from the end F T ln... The luminance signal component, which is a low carrier FM signal, is extracted by the router 11 and converted into a rectangular wave with a constant amplitude by the limiter 13. And the 1st Kanohen 2nd circuit 14
The water + i period signal - which is input to the demodulator 15 and converted into the same luminance signal or divided from the luminance signal with zinc is input to the phase detector 17 or (
(without zinc) A If” ++il, 1s1
The phase information is compared between A1 and Hatake, and the phase information corresponding to the phase is used to control the 8th extension of the first uf variable ν extension circuit 14 via the low-pass filter 18. , the thick components are removed in the first ++"+:O5 extension circuit 14.

In this case, if the cutoff frequency of the low-pass filter 18 is set to about 200 Hz, a zinc component with a small periodic fluctuation such as that which occurs when the VTR is running normally +1 can be removed to 1-min.

- The low-pass conversion colors 4'l-, - extracted by the low-pass filter 12 are frequency-modulated in the FM modulator 19, and supplied to the limiter 20, where they are made into a rectangular wave with a constant amplitude. Then, the signal is input to the second variable delay circuit 21, and the zinc component is removed based on the phase information output from the low-pass filter 18, similar to the luminance signal component.

The FM signal from which the zinc component has been removed is converted to the original low-frequency conversion color signal in the demodulator 22, and then converted to the carrier color in the frequency converter 23 in which the primary color subcarrier frequency (3.58 MHz) is manually input. (Converted to ti number.

Therefore, the brightness output from the demodulator 15 and the frequency 1! ! By adding the carrier color lamps tJ output from the converter 23 by the combining circuit 24, a composite video signal without thick components is output from the end 1'-T1, 1□ blind.

FIG. 2(a) is a circuit diagram showing an example of an analog 4'I intensive control type IIf variable delay circuit za(zt).1. , I-no.

■・・・・・・1. zlXL is a plurality of in-hark circuits connected in series, and VB is a power supply.

Logic,, trtea 6 in z<-'i I t,
I, . Voltage (II
'It changes depending on what you say. Therefore, the operating power supply V ++
By controlling the phase information generated by the phase detector 17 described above, it can be used as a variable delay circuit using an analog signal having nT.) delay times H and H.

FIG. 2(b) is a circuit diagram showing another embodiment of the analogue control-type detour, where A is a shaping amplifier.

Ql and Q7 are complementary nuinching transistors, and S is a current source. The output end of such a gate circuit usually has a positive load (denoted by C5), so the output of each gate circuit is 8 times T depending on the load of this capacity J.・(to) one.

8 The elongation time T9 changes depending on the upstream voltage supplied from the current source S. Therefore, if the current source S of each gate circuit is changed by a Karen I-Miller circuit, etc., the elongation time T9 changes depending on the current value iz, and εr+2 As in the case of Figure (a), an analog 1, 1 control type IIf variable/d extension circuit can be used.

〔Effect of the invention〕

As explained below, the simple, (,h)%Q 111r 1iil supplementary device of the present invention is capable of converting video bows into FM
Since it is configured to control in the state of No. 4i and take the axis fluctuation between h, (1'Fljj+hlt1)
It can be formed only with the circuit of 111-device 1'1 or Hatsutomi's Achilog circuit, making it easy to integrate into an IC, and at the same time, has the effect of reducing the size and reducing the paper storage space.

Therefore, 1f? It has the advantage that it can be added to a standard VTR or the like to improve the image quality.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a simplified time base correction device of the present invention, and FIGS. FIG. 3 is a block diagram of a digital time axis correction device. [In 4, 11 is a bypass filter, 12 is a low-pass filter, 13.20 is a limiter, 14.21 is the first... Second
15.16 is a synchronizing signal separation circuit, 17 is a phase detector, 19 is a frequency modulator, and 23 is a frequency converter. Figure 3

Claims (1)

[Claims] Separating the reproduced video signal into a low carrier FM signal and a low frequency conversion color signal, converting the low carrier FM signal into a luminance signal via a first analog signal controlled variable delay circuit,
The low-pass conversion color signal is frequency-modulated and then converted into a carrier color signal via a second analog signal-controlled variable delay circuit and a demodulation circuit, and the synchronization signal extracted from the luminance signal and the reference synchronization signal are The first and second
A simple time axis correction device characterized in that the time axis of a reproduced video signal is corrected by controlling the amount of delay of an analog signal controlled variable delay circuit.