KR19980051884A - VCR record gain control circuit - Google Patents

Abstract

The present invention relates to a recorder for recording a signal on a videotape by YC separation of NTSC signals input to the VCR when the signal is recorded on a videotape in a VCR, and then mixing the Y and C signals processed in each processing system again. The HPF (8) and LPF (12) and the recording amplifier (14), which are the final stages of the luminance signal (Y) processing system and the color signal (C) processing system of the conventional VCR recording system circuit, are connected to the HPF (8). And a luminance signal (Y) and a color signal (C) input and processed by the LPF 12 to detect a ratio of the two component signals, and compare the ratio difference value with a reference value. By compensating the component of the color signal (C) and outputting it to the recording amplifier 14, the recording amplifier 14 amplifies the NTSC signal in which the mixing ratio of the luminance signal component and the color signal component is constantly amplified to the recording head. Recording gain control means 19 for recording By providing a VCR recording gain control circuit, the recording amplifier 14, which is the last stage of the VCR recording system, receives a recording signal in which the mixing ratio of the luminance signal component and the color signal component is kept constant so that the image of stable image quality is always maintained. This has the effect of being able to record signals.

Description

VCR Record Gain Control Circuit

In the present invention, when recording a signal on a video tape in a VCR, the NTSC signal input to the VCR is separated by YC, and the Y signal and the C signal processed in each processing system are mixed again to record the signal on the video tape. Detects the ratio difference between the luminance signal component and the color signal component, compares the ratio between the detected signal component with the reference value, adjusts the mixing ratio of the luminance signal and the color signal to a constant value, and then amplifies it in the amplifier to record on the tape through the recording head. The present invention relates to a VCR recording gain control circuit in which the ratio (dB) of the luminance component and the color signal component of the recording NTSC signal in the VCR is kept constant at all times.

Figure 1 shows a simple block diagram of a recorder circuit of a video signal in a typical VCR. As can be seen from the above, only the process of recording a signal on a video tape in a VCR is as follows. First, a TV tuner (not shown) or a video camera is shown. When NTSC signal is input from the VCR input system such as (not shown) or other video deck (not shown), the gain of the signal input from AGC (1) is adjusted so that the YC separator (2) comb filter Or the color signal component (C) signal is separated from the NTSC video signal input through the bandpass filter (passing only the color signal around 3.58 MHz), and the synchronization signal and the luminance signal are transferred to the luminance signal processing system. The color signal is sent to the color signal processing system.

The luminance signal Y is determined by the division unit 3 to which frequency the respective levels of the synchronization signal stage (sink chip) and the pedestal are FM-modulated. After correcting to the prescribed size, the pre-emphasis unit 5 is constantly aligned at a level corresponding to the frequency deviation width after FM modulation regardless of the magnitude (contrast) of the luminance signal magnitude in the clamp unit 4. In the demodulation of the signal using a low pass filter (LPF), the high pass is emphasized in preparation for S / N attenuation due to the increase of the high pass noise. After cutting the level of the upper and lower sparks (the upper level cut is a white clip, the lower level cut is a dark clip) to prevent the reversal caused by the high frequency highlight or the deterioration of the S / N. High pass filter by FM conversion of signal It is passed through a high pass in HPF (8) and to the color signal into a low frequency portion.

On the other hand, the color signal C is largely adjusted in order to improve the S / N of the burst signal in the ACC 9 (Automatic Chroma level Control) to emphasize the burst signal in the burst emphasizing unit 10, and then the frequency low range. After the low-pass conversion of the color signal is performed by the conversion unit 11, the LPF 12, which is a low-pass filter, removes the second harmonics outside the color signal carrier frequency (3.58 MHz).

In this way, after the luminance signal Y and the color signal C have been processed for recording in the respective processing systems, the mixer 13 combines the two signal components into one NTSC signal to record the recording amplifier 14. And amplifying the signal in the recording amplifier 14, and then recording the video signal on the tape through the recording head (not shown).

In the video signal recorder of the conventional VCR as described above, as described above, after the luminance signal Y and the color signal C are synthesized in the mixer 13, the recording amplifier 14 in the simple form as shown in FIG. The mixer 13 was inputted and amplified to record the video signal on the tape through the recording head.

In the conventional method of amplifying and recording the NTSC signal synthesized by the mixer 13 in the recording amplifier 14 as described above, the luminance component (Y) and the color component ( There is a problem that it is difficult to maintain a constant recording characteristics of good paper according to the difference of mixing ratio (dB) of C).

In order to solve the above problems, YC separation of NTSC signals input to the VCR, and then mixing the Y signal and the C signal processed in each processing system to record the signal on the video tape, the luminance signal The luminance component signal (Y) and the color signal component signal (C) of the mixed NTSC recording signal outputted from the final stages of the processing system and the color signal processing system are respectively input from the comparator to determine the difference between the mixing ratios (dB) of the respective components. Detects and sends it to a gain controller so that the gain controller feeds back a gain adjustment value according to the ratio difference between the luminance signal component and the color signal component of the recorded NTSC signal, and adjusts the luminance component and the luminance signal that are over and undersized. After the mixing ratio of the color signal is made constant, the amplifier amplifies and records the tape on the tape through the recording head. It is an object of the present invention to provide a VCR recording gain control circuit which makes it possible to increase the image quality of a recorded video signal by keeping the ratio (dB) of the picture component and the color signal component constant.

1 is a partial block circuit diagram showing a circuit portion of a recording system of a conventional VCR;

2 is a block diagram illustrating a related partial block of a Y-C signal recorder mixed when recording a signal on a tape in a conventional VCR;

3 is a schematic block circuit diagram of a VCR write gain control circuit according to the present invention;

* Explanation of symbols for main parts of the drawings

1: AGC2: Y-C separator

3: division part 4: clamp part

5: pre-emphasis section 6: clip section

7: FM modulator 8: HPF

9: ACC10: Burst Emphasis section

11: low frequency converter 12: LPF

13: Mixer 14: recording amplifier

15: Comparator 16: Gain Controller

17: AGC118: AGC2

19: recording gain control means

In order to achieve the above object, the present invention provides a luminance signal and a color signal connected between the HPF and LPF and the recording amplifier, which are the last stages of the luminance signal processing system and the color signal processing system of the conventional VCR recording system, respectively. Detects the ratio of the two component signals, compares the difference between the ratios with the reference values, compensates the degree of each component being oversized under the reference value, and sends it to the recording amplifier to always record the NTSC signal from the recording amplifier. And amplifying a signal in which the mixing ratio of the luminance signal component and the color signal component is kept constant so as to be recorded by the recording head.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention;

Fig. 3 is a schematic block circuit diagram of a VCR recording gain control circuit according to the present invention. In the recording system of the conventional VCR circuit, the HPF (8), which is the final end of each of the luminance signal (Y) and the engraving arc (C) processing system, is shown in Figs. And the luminance signal Y and the color signal C which are inserted between the LPF 12 and the recording amplifier 14 and processed by the HPF 8 and the LPF 12 to receive the two component signals. By detecting the ratio of the ratio and comparing the ratio difference value with the reference value, the components of the luminance signal (Y) and the color signal (C) are compensated and output to the recording amplifier 14, so that the recording amplifier 14 always outputs the luminance signal component. And a recording gain control means 19 for amplifying the NTSC signal in which the mixing ratio (dB) of the color signal components is kept constant and recording the recording head.

The recording gain control means 19 is connected between the output terminal of the HPF 8 and each output terminal of the LPF 12 and the recording amplifier 14 to be processed and input from the HPF 8 and the LPF 12. A comparator 15 which receives a luminance signal Y and a color signal C, compares the ratios of the two component signals, and outputs a difference value; and a comparator 15 connected to an output terminal of the comparator 15; A gain controller 16 for outputting a recording gain control signal by comparing the ratio difference between the luminance signal Y and the color signal C sent from the reference value with the reference value, and the luminance signal Y input terminal of the comparator 15; The recording amplifier 14 adjusts the ratio of the luminance signal Y input to the comparator 15 by the recording gain control signal connected to the output terminal of the gain controller 16 and fed back from the gain controller 16. AGC1 (17) to be output to the output signal, the color signal (C) input terminal of the comparator 15 and the gain controller ( 16, respectively, connected to an output terminal of the output terminal, and adjusting the ratio of the color signal C inputted to the comparator 15 by the recording gain control signal fed back from the gain controller 16 to output to the recording amplifier 14. And AGC2 (18).

As can be seen from FIG. 3, the present invention configured as described above includes an output terminal and a recording amplifier of the HPF 8 and LPF 12 at the end of each processing system for processing the luminance signal and the color signal of the recording system of the VCR. Between 14), the recording gain control means 19 according to the present invention is inserted, and the luminance signal Y processed and input by the HPF 8 and the LPF 12 in place of the conventional mixer 13 is input. And the color signal C are respectively input to detect the ratio of the two component signals, and the ratio difference value is compared with the reference value stored in a separate memory (not shown) to compare each of the input signal components (Y, C). The excess or lack value is compensated for and output to the recording amplifier 14 at the rear end.

That is, the comparator 15 of the recording gain control means 19 receives the luminance component signal and the color signal component signal output from the HPF 8 and the LPF 12 and compares the ratios of the two component signals. When the difference value is output, the gain controller 16 compares the ratio difference value between the luminance signal and the color signal component sent from the comparator 15 with the reference value stored in the memory (not shown) to compare the recording gain control signal with the AGC1. Output to (17) and AGC2 (18) respectively.

Then, in the AGC1 (17) and AGC2 (18) by adjusting the ratio of the luminance signal and the color signal input to the comparator 15 by the recording gain control signal fed back from the gain controller 16, respectively, the rear stage The recording amplifier 14, which is the final stage of the recording system, is used to output the mixed recording NTSC amplified signal to the tape through the recording head (not shown) by outputting the recording amplifier 14 to the recording amplifier 14 of the luminance signal component and the color signal component. Since the mixing ratio (dB) of the input signal is kept constant and amplified and recorded by the recording head, it is possible to always record a video signal of stable image quality.

The VCR recording gain control circuit according to the present invention receives the recording signal in which the mixing ratio (dB) of the luminance signal component and the color signal component is always kept constant by the recording amplifier 14 which is the last stage of the VCR recording system. There is an effect that it is possible to record a video signal of stable picture quality at all times.

Claims (2)

In the recording system of the conventional VCR circuit, instead of the mixer 13 between the HPF 8 where the luminance signal Y processing system is the final stage and the LPF 12 and the recording amplifier 14 which are the final stage of the color signal C processing system, The luminance signal (Y) and the color signal (C) which are inserted and processed by the HPF 8 and the LPF 12 are input, detect the ratio of the two component signals, and compare the ratio difference value with the reference value. NTSC, which compensates the components of the luminance signal (Y) and the color signal (C) and outputs them to the recording amplifier (14) so that the mixing ratio (dB) of the luminance signal component and the color signal component is always maintained in the recording amplifier 14. And a recording gain control means (19) for amplifying the signals so that the signals can be recorded by the recording head. 2. The recording gain control means (19) according to claim 1, wherein the recording gain control means (19) is connected between the output end of the HPF (8), each output end of the LPF (12), and the recording amplifier (14). A comparator (15) for receiving the luminance signal (Y) and the color signal (C) which are processed and inputted in the circuit, and comparing the ratios of the two component signals and outputting the difference values; A gain controller 16 which is connected to an output terminal of the comparator 15 and outputs a recording gain control signal by comparing the ratio difference between the luminance signal Y and the color signal C sent from the comparator 15 with a reference value; Wow; Luminance input to the comparator 15 by a write gain control signal connected to the luminance signal Y input terminal of the comparator 15 and the output terminal of the gain controller 16 and fed back from the gain controller 16. An AGC1 (17) for adjusting the ratio of the signal (Y) and outputting it to the recording amplifier (14); A color signal (C) input to the comparator 15 by a write gain control signal connected to a color signal C input terminal of the comparator 15 and an output terminal of the gain controller 16 and fed back from the gain controller 16. And a AGC2 (18) which adjusts the ratio of C) and outputs it to the recording amplifier unit (14).