KR0113073Y1 - Lowband vestigial sideband elemination circuit for vcr color signal - Google Patents

Abstract

The present invention relates to a color signal low pass conversion residual sideband cancellation circuit of a VCR, and includes a high pass filter unit, two 1H delay units, and a C-RSR unit between a low pass filter and a burst emphasis unit in a conventional VCR color signal recorder. In addition, by removing the 2fsc component that interferes with the luminance signal when recording and reproducing the sideband of the color signal low-converted by the frequency changer, the S / N ratio of the image signal can be improved and the cause of image quality roughness such as butt can be compensated. It is possible to improve the reliability of the product.

Description

Residual Sideband Reduction Circuit of VCR's Color Signal

1 is a schematic block diagram of a conventional VCR color signal recorder.

2A is a frequency spectrum of a luminance signal and a color signal during recording in a conventional VCR.

b is an enlarged view of part A of a.

3 is a schematic block diagram of a color signal recorder to which a circuit of the present invention is connected.

4 is a detailed view of the color signal low-conversion residual sideband removal circuit of the present invention.

5 is an operation waveform diagram of each part of the color signal low-conversion residual sideband removal circuit of the present invention.

* Explanation of symbols for main parts of the drawings

1: band pass filter unit 2: color automatic control unit

3, 4 main and sub frequency converter 5 low pass filter unit

6: burst emphasis portion 7: recording killer portion

8: record amplifier 9: C-RSR unit

91: high pass filter 92, 93: 1H delay unit

94: adder

The present invention relates to the image processing of the VCR. In particular, the high-sideband components other than the low-conversion color signal band generated when recording the low-frequency color signal are prevented from interfering with the luminance signal band, so that the S / N ( The present invention relates to a color signal low-conversion residual sideband elimination circuit of a VCR capable of compensating for a cause of degradation of a signal / noise) and a roughness of image quality.

In the conventional VCR, the color signal recorder maintains a constant color signal level output from the band pass filter 31 and the band pass filter 31 for separating the color signals in the video signal, as shown in FIG. Main and sub frequency converters 33 and 34 for low-converting the color signals output from the automatic color control (ACC) 32 and the color automatic control unit 32, respectively: the main frequency converter 33 Burst Emphasis that improves the S / N ratio of the color signal output from the low pass filter unit 35 and the low pass filter unit 35 that passes only the color signal band converted to the low band among the color signals output from Section 36 and a recording killer section 37 for judging the presence or absence of a color signal, and a recording amplifier 38 for amplifying a predetermined level to sufficiently record the original signal and applying it to the magnetic head HEAD. By configuring the connection It was.

Therefore, the band pass filter 31 separates only the color signal of 3. 58 MHz from the input video signal, and the color automatic control unit 32 receives the color signal by constantly adjusting the color signal to a predetermined level. Will be entered in.

At this time, in the main frequency converter 33, a predetermined signal of 4.21 MHz output from the sub-frequency converter 34 and 3. 58 MHz output from the color automatic control unit 32 to low-convert and record the color signal. The frequency component of the low-conversion color signal of 629 kHz, which is the difference between the predetermined signals, is obtained.

Thereafter, the low-converted color signal is filtered at about 1.1 MHz through the low pass filter unit 35 and then amplified to a double level through the burst emphasis unit 36 to improve the S / N ratio.

In addition, the recording killer 37 receiving the output signal of the burst emphasis unit 36 blocks the color signal path so that the luminance signal does not become a noise when there is no color signal, and in the recording amplifier 38, the recording killer unit Since the output signal at 37 is amplified to a predetermined level and applied to the magnetic head HEAD, a predetermined video signal is recorded on the tape.

In this way, the low-frequency conversion color signal frequency (629 ± 500 kHz) is obtained by the output signal (3.58 MHz) of the color automatic controller 32 and the output signal (4.21 MHz) of the sub-frequency converter 34 in the main frequency converter 33. When obtained, the upper and lower bands of the low-converted color signal frequency (fs = 629 ± 500 kHz) are generated, and 2fsc (about 1.258MHz) of these components interferes with the luminance signal during reproduction, thereby causing beats. Interference, also known as interference, appears on the playback screen.

Therefore, conventionally, in order to compensate for this, when there is an ideal frequency interleaving relationship between the luminance signal and the color signal frequency, mutual interference is given by a predetermined phase difference between the color signal and the luminance signal as shown in FIG. Although the frequency of the color signal changes due to the change of the time axis caused by jitter during recording and playback, the frequency interleaving of the residual side wave is removed and mutual interference occurs. In particular, the 2fsc component has a large influence in the luminance band. There was a problem given.

In addition, the recent high-definition in the S-VHS (S-VHS) has been a situation that a significant restriction on the luminance signal interference of the color signal.

Accordingly, an object of the present invention is to provide a main frequency by adding a color signal low conversion residual sideband removing unit (hereinafter abbreviated as C-RSR unit) between a low pass filter and a burst emphasis unit in a conventional VCR color signal recorder in view of the problems of the prior art. The high frequency band components other than the low frequency band color signal band interfere with the luminance signal band by removing the 2fsc component of the side band of the low frequency converted color signal fs before recording and recording the mixed color signal with the luminance signal. The reason is to compensate for the cause of image quality roughness such as degradation of S / N ratio and beat.

Hereinafter, the present invention with reference to the accompanying drawings as follows.

As a specific means for achieving the above object, an unshown input unit for inputting a color signal having a carrier frequency between 0,5 MHz and 1 MHz and a sideband component of the frequency multiple, and at least 1.1 MHz of the color signal of the input unit; A high pass filter for passing a frequency, a line delay for reversing the output signal of the high pass filter, and an adder for adding and outputting the output signal and the input color signal of the lazy retarder. .

The color signal may be converted and input so that the phase shifts by 90 ° in units of one horizontal line scan signal of the original image signal.

Referring to Figures 3 to 5 the effect of the circuit of the present invention configured as described above is as follows.

First, the band pass filter unit 1, the color automatic control unit 2, the main and sub frequency converters 3 and 4, the low pass filter unit 5, the burst emphasis unit 6, the recording color unit 7 and Since the operation of the recording amplifier 8 is the same as in the conventional VCR, it is omitted to avoid duplication.

In addition, since the low-pass color signal fsc is output through the low pass filter part 5, the color signal inputted to the high pass filter part 91 in the C-RSC part 9 is equal to 2 as shown in FIG. In the high pass filter 91, which passes a high frequency signal of about 1.1 MHz because the signal includes the upper side band (fsc + 2fsc), the fsc component in the color signal is removed as shown in (b) of FIG. 5 and the high sideband of 2 fsc or more. Only passed.

Thereafter, the 1fsc component is reversed 90 ° out of phase as shown in (c) of FIG. 5 through the 1H delay unit 92, and then through 90H as shown in (d) of FIG. 5 through the 1H delay unit 93. Since the phase is reversed, the 2fsc component having passed through the 1H delay portion 93 is applied to the adder 94 by inverting a total of 180 degrees when outputted from the high pass filter 91.

That is, in the VHS method, when the color signal is recorded, the ps method is used to shift the phase by 90 ° between 1H. Thus, the scan line outputted from the 1H delay unit 93 by shifting between 2H is 180 degrees than the scan line output from the low pass filter unit 5. It has a phase difference of °. Here, ps (phase shift record system) method is used to remove cross talk of low frequency color signal that is not improved by azimuth recording and reproduction method. This method is called low frequency conversion color signal. Record the phase of (629㎑) by 90 ° every horizontal synchronization.

In addition, in the adder 94, the fsc + 2fsc signal output from the low pass filter unit 5 is added to the 2fsc signal inverted by 180 degrees out of the 1H delay unit 93. As in (e), only the fsc signal having the phase of the original signal is output.

Therefore, the color signal input to the burst emphasis unit 6 is only applied to the fsc component from which the 2fsc component which removes the luminance emerging interference during reproduction is applied, so that the image signal recorded on the tape has only the pure fsc component. Band interference can be prevented.

As described above, according to the present invention, when recording a predetermined video signal through a VCR, the high sideband component (2fsc) contained in the color signal is removed before recording to tape by mixing with a luminance signal. It is possible to prevent the interference of the luminance signal band of the color signal to not only improve the S / N ratio of the video signal but also to obtain a beautiful image quality can further improve the reliability of the product.

Claims (2)

An input unit (not shown) for inputting a color signal having a carrier frequency between 0.5 MHz and 1 MHz and a sideband component of multiples of the frequency, a high pass filter unit for passing a frequency of 1.1 MHz or more of the color signal of the input unit; And a line delay for inverting the output signal of the high pass filter in phase and an adder for adding and outputting the output signal of the line delay and the input color signal. The VCR of claim 1, wherein the color signal is inputted after being shifted by 90 ° with respect to one horizontal line scan signal of the original video signal.