JPS58215888A - Color signal processor - Google Patents

Abstract

PURPOSE:To simplify a circuit and to eliminate unnaturalness between PAL and NTSC, by applying subcarrier having specified phase difference to a killer detecting means of a PAL and an NTSC signal processing circuit. CONSTITUTION:A switch SW1 is placed at a terminal side (a) for PAL by a mode switching signal 54 and a color signal from an AGC circuit 11 is divided into two systems of a 1H (one horizontal scanning period) delay line 12 and a direct signal; and they are applied to a B-Y demodulator 6 and an R-Y demodulator 7 through an adder 14 and a subtracter 15 respectively. The SW1 is placed at a terminal side (b) for NTSC, and only the direct wave is applied to the demodulators 6 and 7. Further, a switch SW2 is inverted alternately at intervals of one horizontal period by the signal 54 in PAL mode and switches 60 and 61 are fixed at contact sides (b) in NTSC mode. The subcarriers 36 and 37 applied to the killer detector 3 are 45 and 225 deg. out of phase with a 180 deg. burst respectively. Switches 64 and 65 are operated to apply signals 40 and 41 which are inverted in phase at intervals of one horizontal period. The switches 64 and 65 are fixed at the contact sides (b) in NTSC mode.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to color signal processing for a multi-scheme color television receiver, and its purpose is to process NTSC signals and PA signals.
I. The purpose is to share the circuit used for signal color demodulation.

Color television signals currently in use around the world can be roughly divided into NTSC, PAL, and SECAM systems, each of which has its own unique characteristics, and receivers suitable for each system have been manufactured.

In recent years, with the spread of broadcasting and the diversification of media that convey video information, the number of regions and opportunities where it is possible to receive or receive color television signals of multiple formats has increased, and the number of areas and opportunities that can receive or receive color television signals of multiple formats has increased. Many machines are also made. One that can receive images in the three systems mentioned above, one that can receive images in PAL and SRCAM2 systems, and in addition to those that can receive images in the above three systems, a color subcarrier frequency of 4.433618 MHz (hereinafter referred to as 4.
NTSC signal (abbreviated as 43MH2) (this iMod
There are also devices that can receive a total of four types of signals. Since these receivers process color signals of various systems, the color signal processing circuit is inevitably complicated, and the number of parts and man-hours are also large. Therefore, the circuit that processes all the color signals of multiple methods can be simplified and economically rationalized! There is a demand for miniaturization.

The present invention provides PAL
The purpose is to share the common parts of the signal processing circuits of the NTSO and NTSO, simplify and rationalize the circuit, improve characteristic performance, and ensure good image reception performance.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows the main parts of an NTSC demodulator. The color signal inputted from the color signal input terminal 50 follows the ACC circuit 11 and is sent to the APC detector 4. Killer detector 3, B-Y demodulator 6.
RY demodulator 7. The oscillation output of the voltage controlled oscillator 1 passes through the phase shifter 2 for TINT control, and the APC@
It is added to the wave detector 4 and the killer detector 3. capacitor 8,
10 and crystal 9 are voltage controlled oscillators 1.1 which are oscillation elements of voltage controlled oscillator 1. TINT control phase shifter 2. The Ap'c detector 4 and the load pass filter 6 are P L L (PHA
SELOCKIi:D LOOP) all configured, NTS
The differential phase of the differential input 34°36 of the APC detector is 90 with respect to the C burst phase (1800).

30 to 37 are subcarriers locked to the burst phase. The subcarriers 30, 31, 32, 33 are applied to the control phase shifter 2 by the control voltage 22.
It is variable by ±4C. B-Y demodulator 6 has o
918σ subcarriers 7113o, 31 are input, while R
- Y demodulator 7 has 9o', 27o subcarriers 32.33
is manpower.

FIG. 2 shows a circuit diagram of the actual TINTN path 2.

In addition, Fig. 3 shows the phase vector diagram of each part at the center of TINT,
FIG. 4 shows a phase vector diagram of each part when the TINT control voltage 22 is varied.

In the second transistor, transistors #201 and 202 are constant current sources, 220, 223, and 224 are appropriate DC bias voltages, 230 to 236 are resistors, and 30° 31, 32, and 33 are the aforementioned subcarriers. The transistors 207 to 214 are connected to 34 to 3 by the TINT control voltage (22a-22b).
7 subcarrier phase r30 to r33.

(Phase of 34 - Phase of 35) is 900 compared to the burst phase of 1800 due to the nature of the Apc loop.As a result, subcarriers 30 to 33 each change the phase of σ 1800°9σ and 2aσ by 45°. be able to. 30 in Figure 3
1. 401 in the 41st line indicates the Nl5C burst phase.

In the following explanation, it will always be assumed that TINT center 22a=22b. Therefore, the phase relationship of the subcarriers is as shown in FIG.

On the other hand, the killer detector has 45° positive phase on 36 and 1 on 37.
A 35° phase subcarrier is added.

Next, FIG. 5 shows a block diagram of a system of the present invention which is based on the above-mentioned NTSC system and is also capable of receiving images of the PAL system. For simplicity of explanation, PAL/Modified N T
The SC image receiving system will be explained.

Only the differences from the NTSC system shown in FIG. 1 will be explained.

A CC circuit 11', r output ft color signal 1rJ-P A
L/N T S G mode switching signal 54 causes P
When AL, SW1 becomes terminal a, and 1H delay line 12
The adder 14 is divided into two systems: a full signal and a direct signal.
, are added and subtracted by the subtractor 15, respectively, by the B-Y demodulator 6.
, and R-Y demodulator 7. NTSC time SW1
becomes the b terminal and only the direct signal is applied to the demodulator 6.7.

For PAL systems, burst bar +1350 per horizontal period
, it can be transmitted with a phase of -136°, but if the time constant of the low-pass filter 5 of the PLL is made thicker, the phase becomes +135°',
-135 to lock to the average phase of 1800,
The subcarriers 30 to 36 are as shown in FIG. 3, similar to NTSC. (TINT control is not performed during PAL, so TINT
(The control signal 22 is fixed at the center.) Furthermore, in the PAL system, the phase of the R-Y component is inverted every horizontal period, so the sub-carrier to be applied to the R-Y demodulator 7 is switched 60° in accordance with this. 6Q and phase inverter 6
PAL/N-TSC switching control signal 54 using 2.63
According to the PAL mode, normal demodulation is performed by switching and inverting 5w24 every 1-j horizontal periods. At the time of NTSC,
The switches 60 and 61 are fixed on the contact side.

Subcarrier l added to killer detector 3! 1.36°37
In the NTSC system shown in Figure 1, 45' and 135' phases were added to the burst phase of 180°C, but
In the NTS C/PAL dual-use system, 45', 2
Add 25°. The purpose of this method is to perform line identification when the killer detector is in PAL mode. According to the control signal 54, the switches 64 . 65 is operated, and a phase-inverted signal 40.41i is added every -horizontal period. NTSC
Sometimes the switches 641 and 65 are fixed at contact B.

Figures 6 and 7 show the state of killer detection. n, n+1 in FIGS. 6 and 7. n+2 is different at the n-th point. This causes inconveniences such as the killer becoming shallow at t6 P A L.

A block diagram of an embodiment of the present invention is shown in FIG. In this embodiment, in order to eliminate the above-mentioned inconvenience, P A L, /
Subcarrier 36 added to killer detection at NTSC
, 37 phase at N780: 45°, 226PPAL
A simple circuit for switching between 90° and 270° is provided. The internal medicine department located south of the 13th block is PA L/N T.
This is the same as in FIG. 5 except that the SC switching signal 54 is connected to the TINT circuit 2.

A detailed circuit of the embodiment is shown in FIG. This 1ixl path is a part of the 1° INT circuit 2 in FIG.

As shown in FIG.
, 702, and the common base 703 of transistors 701 and 702 is set to a higher potential than the bases of 203 and 204 during PAL, and lower than the bases of 203 and 204 during NTSC.

FIG. 9 shows the phase of each part in NTSC mode, and FIG. 10 shows the phase in PAL mode. This case is exactly the same as the previous explanation. FIG. 10 shows the phase of each part during PAL. In this case, the B-Y axis 0 axis direction 0 direction carrier wave 30.31 is not input, so 34. The phase of 36, 36°37 is 90°, 27
♂, 9dO+2yO°.

The differential input phase applied to the APC detector 4 is 90° both in PAL and NTSO, and the differential input phase applied to the killer detector 3 is 90' in PAL.

It becomes 45° at NloSC. This situation is shown in Figure 11,
Shown in Figure 2.

As described above, according to the present invention, there is no difference in killer sensitivity between both PAL/NTSC systems, and unnaturalness between the two systems can be eliminated.

[Brief explanation of the drawing]

1 (9) idN"l' SG A block diagram of a G system color television receiver, and Figure 2 is a TINT of the same receiver.
Circuit diagram of the circuit, Figure 3 is a vector diagram showing the phase of the center part when TINT is at the center, Figure 4 is a vector diagram showing the phase of each part when the same TINTy is converted, Figure 5 is id P AL / N T
A block diagram of a color television receiver for an SC dual-use system. Figures 6 and 7 are vector and waveform diagrams of the killer detection of the same receiver. Figure 8 is a vector and waveform diagram of the error detection output. Figure 13. FIG. 1 is a block diagram of a color signal processing device according to an embodiment of the present invention. 1... Voltage controlled oscillator, 2... Phase shifter, 3... Killer detector, 4... A20
m-wave device, 5...Low pass filter, 6...
...B-Ya modulator, 7...R-Y demodulator, SW
l, SW2...Switch, 14...Adder, 15...Subtractor, 12...1H toilet line, 60.61, 64.65. ...Switch, 54...Control signal, 62, 63, 66
．． 67... Phase inverter. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 3/? -Y# 96' P-Yk /? r Fig. 6 High Stoy Button h ntr tH2n4J
n+4 (#6h, * -4/I?M-year-old 1
1) Figure 7B JtL n+Z n+2
7+t4Figure 8Figure 9Figure 10Figure 11Figure 12

Claims (1)

[Claims] a switch means for switching between a first color television signal reception mode and a second color television signal reception mode; and an APC color synchronization means for reproducing a color subcarrier from the burst signal;
It is equipped with a killer detection means for phase detecting a burst signal to extract a killer output, and a phase shift means for shifting the phase of the subcarrier et in the APC loop, and the switch means shifts the phase of the subcarrier applied to the killer detection means. In the first reception mode and the second reception mode (-j-shige) (however, n-0゜1
．． 2. 3... A color signal processing device characterized by providing a phase difference of liradians.