KR970004672Y1 - Luminance and chrominance processing circuit of pal based vtr system - Google Patents

Abstract

None.

Description

Brightness / color (Y / C) processing circuit of VCR of PAL system

1 is a conventional circuit diagram

2 is a circuit diagram according to the present invention

3 is a concrete circuit diagram of the holding circuit 20 of FIG.

4 is an operating waveform diagram of FIG. 3, which is a waveform diagram when a PAL color signal is input;

5 is an operational waveform diagram of FIG. 3, which is a waveform diagram when SECAM color signal is input,

6 is a gain characteristic diagram of 4.43mhz of the bandpass filter 301 of FIG.

7 is a characteristic diagram of the 1 / 2fh tuning circuit 302 of FIG.

8 shows reference levels in the first and second comparators 22 and 23 of FIG.

The present invention relates to a luminance / color (Y / C) processing circuit in a VCR system. In particular, the present invention compensates for luminance noise and drop-out signals in a charge couple division (CCD) of luminance signal processing. / SECAM) relates to a luminance / color (Y / C) processing circuit of a VT system in the form of an arm (PAL) integrated so as to be able to process the discrimination function together.

In the Y / C processing of the conventional VCR, particularly in the PAL method, three integrated circuits are formed as shown in the first diagram. One is a Y / C processing circuit 10 and the other is a luminance noise canceling and dropout compensation circuit 20 that compensates for luminance noise rejection (YNR) and dropout, so as to detect a PAL / SECAM color scheme from the color signal. The PAL / SECAM color system detection circuit 30 is used.

In the above configuration, an interface circuit is added between the parts by design, and power supply of each part is provided separately, so that it is difficult to obtain desired operating characteristics such as power noise, and the design becomes complicated, There was a problem.

Therefore, the purpose of the present invention is to reduce the cost by simplifying the configuration of the system design by using one chip but reducing the interface circuit between each part, and reduce the power supply noise by using the power and ground in common. It is to provide a circuit that can be facilitated.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

2 is a circuit diagram according to the present invention,

The clamp circuit 11 is connected to the YNR and the dropout end YD of the Y / C processing circuit 10, and the clamp circuit 11 receives the YNR and the drop arrest signal under the control of the automatic bias circuit 14. Clamp, the output of the clamp circuit 11 is applied to the CCD circuit 12, the CCD circuit 12 is controlled by the output of the divider 15, the divider 15 is an amplifier 17 And the amplifier 17 moderates the output of the duty adjustment circuit 16 and the duty adjustment circuit 16 adjusts the output of the divider 15 to provide it to the amplifier 17.

A sample / hold (S / H) circuit 13 is connected to an output terminal of the CCD circuit 12 to compensate for the YNR and a drop signal and to input the Y / C processing circuit 10. The switch 18 is connected to the output terminal 01 of the Y / C processing circuit 10, the amplifier 19 is connected to the output terminal of the switch 18, and the sensing circuit is connected to the output terminal of the amplifier 19. 20, a transistor 21 connected to the sensing circuit 20, a first comparator 22 connected from the transistor 21, and an output of the first comparator 22 is connected to a second comparator. A PAL / SECAM color scheme is detected by connecting the 23, but the first comparator 22 compares with the first reference value ref2 and the second comparator 23 compares with the second reference value ref2. / SECAM color scheme is detected and input to the Y / C processing circuit 10.

3 is a detailed circuit diagram of the sensing circuit 20 of FIG.

A band pass filter 301 for inputting a color burst signal of the amplifier 19 to band pass filter the signal of 4.43 MHz;

A 1 / 2fh tuning circuit 302 for tuning to 1 / 2fh from the output of the bandpass filter 301, and an integrating circuit 303 for integrating the output of the 1 / 2fh tuning circuit 302 do.

4 is an operating waveform diagram of FIG. 3, which is a waveform diagram when a PAL color signal is input;

5 is an operational waveform diagram of FIG. 3, which is a waveform diagram when SECAM color signals are input.

(4a) and (5a) are examples of input color burst signals of the band pass filter 301,

(4b) and (5b) are examples of output signals of the bandpass filter 301,

(4c) and (5c) are examples of output signals of the 1 / 2fh tuning circuit 302,

4d and 5d are examples of the output of the integrating circuit 303.

6 is a gain characteristic diagram of 4.43mhz of the bandpass filter 301 of FIG.

FIG. 7 is a characteristic diagram of the 1 / 2fh tuning circuit 302 of FIG.

8 shows reference levels in the first and second comparators 22 and 23 of FIG.

Therefore, a specific embodiment of the present invention will be described in detail with reference to FIGS. 2 through 8, and the FM luminance FMY is input to the Y / C processing circuit 10 to output the YNR and the dropout stage YD. After biasing according to the output of the automatic bias circuit 14 in the signal roll clamp circuit 11 and delaying according to the output of the frequency divider 15 in the CCD circuit 12, the sample / hold circuit 13 is sampled. The YNR and the dred out signal are compensated and input to the Y / C processing circuit 10.

The Y / C processing circuit 10 amplifies an FM color (FMC) signal at 3,58 MHz in the amplifier 19 through the switch 18, and then filters and inputs the FM color (FMC) signal to the sensing circuit 20.

The sensing circuit 20 detects PAL and SECAM color signals. As shown in FIG. 4A, the PAL signal has a constant frequency of 4.43 MHz in each burst signal, and a SECAM signal as shown in FIG. 5A. It can be seen that 4.44MHz and 4.42MH _Z alternately exist for each line.

When the signals pass through the band pass filter 301 of 4.43MHZ, the PAL and SECAM color signals can be distinguished as shown in FIG. In FIG. 6, when the characteristics of the band pass filter of 4.43MH _Z and the configuration of the PAL and SECAM color signals are considered at the same time, it can be seen that outputs such as (4b) and (5b) are generated.

In the case of PAL, the level corresponding to (6c) is continuously generated. In case of SECAM, (6b) and (6a) are alternately output.

The outputs of (4b) and (5b) have the characteristics similar to those of the bandpass filter 301 of (4c, 5c) in the 1 / 2fh tuning circuit 302, but when the PAL signal is inputted, Since the frequency is fh, it is output at the level of 701, and in the case of SECAM, it is output at the level of 702 because it is input at 1 / 2fh period. The outputs 4c and 5c of the 1 / 2fh tuning circuit 302 are input to the integrating circuit 303 to generate a DC level containing pulse flow such as 4d and 5d.

The magnitude of the signal of (4c, 4d) is (t, H) is larger than the magnitude (nt, nH) of (5c, 5d). The output of the sense circuit 20 sensed as described above is input to the base of the transistor 21. The transistor 21 is driven according to the output of the sensing circuit 20 to compare the output of the transistor 21 with the first and second reference values ref1 and 2 in the first and second comparators 21 and 23. The first comparator 22 compares the first reference value ref1 from the output of the transistor 21. The first comparator 22 outputs “low” in case of 701 of FIG. 7, and outputs “high” in case of 702. Thus, the reference voltage is made to be halfway between 802 and 801 in FIG.

The output of the first comparator 22 is input to the second comparator 23 and compared with the second reference value ref2. The second comparator 23 performs the same function as the first comparator 22 once more. By driving the current of the output signal, it also performs the inverting function. That is, when the output of the first comparator 22 outputs "high" in the SECAM color signal, the output of the second comparator 23 outputs "low".

In the PAL date and time, the output of the second comparator 23 is reversed, and the PAL / SECAM color broadcast method is detected and input to the Y / C processing circuit 10.

As described above, one chip is used, but the inter-interface interface circuit is reduced to simplify the design of the system design, thereby reducing the cost, and the common use of the power supply and the grounding part can reduce power supply noise, thereby improving operation reliability and facilitating integration. In addition, YNR and drop-out compensation and PAL / SECAM color detection can be performed in one chip, so the design can be easily integrated and the competitiveness of the VCR can be enhanced.

Claims (1)

In the luminance / color (Y / C) processing circuit of a PAL type VT system having a Y / C processing circuit 10, the YNR and drop of the Y / C processing circuit 10 are provided. The clamp circuit 11 is connected to the out end YD, and the clamp circuit 11 clamps the YNR and drop-out signals under the control of the automatic bias circuit 14, and the output of the clamp circuit 11 is Is applied to the CCD circuit 12, the CCD circuit 12 is controlled by the output of the divider 15, the divider 15 is controlled by the aeration 17, and the amplifier 17 The output of the duty adjustment circuit 16 is amplified, and the duty adjustment circuit 16 adjusts the output of the divider 15 to provide it to the amplifier 17, and at the output terminal of the CCD circuit 12, a sample / hold ( S / H) circuit 13 is connected to compensate for the YNR and drop signal to input to the Y / C processing circuit 10, the switch to the output terminal 01 of the Y / C processing circuit 10 Connect (I8), The amplifier 19 is connected to the output terminal of the switch 18, the sensing circuit 20 is connected to the output terminal of the heavy amplifier 19, and the transistor 21 is connected to the sensing circuit 20. The first comparator 22 is connected from the transistor 21, and the output of the first comparator 22 is connected to the second comparator 23 to detect a PAL / SECAM color scheme, but the first comparator 22 is detected. Is compared with the first reference value (ref1), and the second comparator 23 is configured to detect the PAL / SECAM color scheme by comparing with the second reference value (ref2) and input it to the Y / C processing circuit 10. Circuit.