JPS5880992A - Multisystem color signal processing circuit - Google Patents

Abstract

PURPOSE:To simplify circuit constitution greatly by composing a common part with one circuit, and switching circuit characteristics to the PAL and NTSC systems according to the systems. CONSTITUTION:When switches S1-S5 are placed at sides of a terminal (a), a take-off circuit 2 turned to 4.43MHz is selected, a 1H (one horizontal scanning period) delay circuit 10 is interposed in a chrominance signal path, and the 4.43MHz crystal CR1 of a PAL hue regulating circuit 15 is selected. Further, the horizontal pulse circuit extending from a terminal 22 to an FF21 is put off to select the PAL system. Then when the switches S1-S5 are placed at sides of a terminal (b), the circuit 2 is selected, the circuit 10 is put off the line, and an NTSC hue regulating circuit 16 and CR1 are selected to earth horizontal pulses through the switch S5. Thus, the NTSC (4.43MHz) system is selected. When the switches S1-S5 are placed at sides of a terminal (c), a 3.58MHz take-off circuit 3 and 3.58MHz crystal CR2 are selected to select the NTSC (3.58MHz) system.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-system color signal processing circuit in a color television receiver capable of receiving color television broadcasts of at least 42 systems including the NTSC and NTSC systems.

Currently, color television broadcasting in Japan is carried out using the NTSC system, but with this NTSC system, hue shifts are likely to occur due to the effects of phase distortion in the transmission path, so the KPAL system was developed to prevent this hue shift. . In this PAL system, the phase of one subcarrier for color signal transmission is inverted to +90 degrees and -90 degrees for each scan, and according to this, the transmission system is The hue error due to the influence of the differential phase of K becomes opposite for each scanning line and is canceled out between the two scanning lines.

As mentioned above, the PAL system is an improvement over the NTSC system, and therefore the circuit configuration on the affected machine side is also different. A delay circuit and other circuits are required, so K, which realizes a color television receiver for both the PAL system and the NTSC system, requires a circuit compatible with both systems. Furthermore, it is necessary to ensure that there is no difference in hue, etc., no matter which broadcast is received.

Conventionally, as shown in FIG. 1, the PAL color signal processing circuit A and the NTSC color signal processing circuit B are configured as separate circuits, and the color difference output of one of the circuits is
It was planned to switch from the system switch circuit CK and add the matrix circuit DK.

However, this conventional circuit contains a common circuit
However, the circuits for PAL and NTSC are completely separate, which is extremely disadvantageous in terms of cost.

The present invention has been made in view of these points, and its purpose is to configure the common part with one circuit,
KL so that circuits with TSCII can be switched according to the system.
Therefore, it is an object of the present invention to solve the above-mentioned problems and provide a nine-way color signal processing circuit.

Hereinafter, the present invention will be explained by examples. Figure 2 shows subcarrier frequencies of 4.43 MHg for the OPAL system, subcarrier frequencies of 4.43 MHg for the NTgC system (however, this is used only in VTRs), and subcarrier frequencies of 3.
．． An embodiment of a color signal processing circuit capable of selecting a royal system for a 58 MHg NTgC system will be shown. The portion surrounded by block 2 is a common color signal processing circuit.

1 is an input terminal into which a composite video signal is input, and K is a chroma input circuit to which a tick-off circuit 2 tuned to 4.43 MHgK and a tick-off circuit 3 tuned to 3.58 MHg are connected in a branched manner. , the carrier color signal and the burst signal are extracted from the composite video signal. Then, one of the tick-off circuits 2 and 3 is selected by the switch S1 and added to the ACC amplifier circuit 4.

This loop consisting of the ACC amplifier circuit 4, chromaticity amplifier circuit 5, burst amplifier circuit 6, and ACC detection circuit 1 is
The C circuit consists of an automatic saturation control circuit that automatically adjusts variations in color saturation caused by variations in received electric field strength, variations in local oscillation frequency, impedance mismatch between the antenna and receiver, and other causes. It works to always maintain a constant color saturation. The burst signal contained in the pack pouch of the horizontal synchronization signal is transmitted to the chromaticity amplification circuit 5 by the gate pulse.
One output of the chromaticity amplification circuit 5 is input to the chromaticity output circuit 8 and further input to the delay amplification circuit 9.

In this delay amplifier circuit 9, output signals are obtained from the output side and the collector side of the F transistor Q, and the output from the collector side is inputted to the IH delay current circuit 10 by the switch SsK. There is. The coil side constitutes the PAL matrix 11, and the side (■) receives the signal from the power supply side of the transistor and the IH delay circuit 1.
At 0111, the signal from the shrine IH delay circuit 10 and the signal from the shrine IH delay circuit 10 are vector subtracted. In other words, P
When a signal for the AL system is input, a carrier color signal of the same phase (B-Y carrier color signal) appears in each horizontal cycle on OII', while a carrier color signal of the same phase appears on the θ side in each horizontal cycle. A carrier color signal (RY carrier color signal) having a phase difference of 180 degrees and a phase difference of 90 degrees from the signal of 0 degrees appears. Then, it is inputted separately to a B-Y demodulation circuit 12 and an R-Y demodulation circuit 13 that perform color difference demodulation, and the output of the nuclear demodulation circuits 12 and 13 is inputted to a matrix circuit 14, where a G-Y output is generated. It is now possible to do so.

The output side of the burst amplification circuit 6 described above includes a hue adjustment circuit 15 for PAL system and a hue adjustment circuit 16 for NTSC.
The output sides of the differential circuits 15 and 16 are connected to K so that they are selectively selected by a switch SsK.
It has become. In principle, in the PAL system, there is no variation in hue, so the PAL candle hue adjustment circuit ISK is provided with a semi-fixed variable resistor VR1 on the internal circuit board etc. for adjustment only during manufacturing. In the NTSC system, there may be variations in hue, so the hue adjustment circuit 16 for the NTSC system is provided with a variable resistor VR2 that should be attached to the surface of the adjustment operation panel of the K11ll so that adjustment can be made even during use.

The output side of the switch Sl is inputted to a phase detection circuit 17, and this phase detection circuit 1T is an APC (automatic The sub-intermediate signal is directly sent to the B-Y demodulation circuit 12 and sent to the 1-to-9 R-Y demodulation circuit 13 via the PAL switch circuit 19, respectively, as the same side detection signal. I'm joining.

The subcarrier oscillation circuit 18 has a reference carrier wave number of 4.43MHg oscillation crystal CR, 3,58M.
A crystal CR for Hz oscillation is attached externally, and one of these crystals CR and CR is selected by a switch 54.

The output side of the switch Ss is further input to a color killer detection circuit 20, which detects the presence or absence of a burst signal and the presence or absence of phase inversion of +90 degrees and -90 degrees of subcarrier R-Y. The detection output is input to a chromaticity output circuit 8 and a flip-flop (T type) 21. The wrinkle flip-flop 21 is a color killer detection circuit 2
0 does not detect the above-mentioned inversion, it holds the inverted state to one side and turns the PAL switch circuit 19 by +90 degrees (or -
The state 111 is switched to the 90 degree) side to function as a 90 angle phase shift circuit, and the color killer detection circuit 20
When detecting the above-mentioned inversion, it is inverted and restored every time it receives a horizontal pulse applied to the terminal 22, and the PAL switch circuit 1
9 to +90 degrees and -90 degrees. Note that the horizontal pulse is allowed to escape to the ground depending on whether the PAL switch is switched off or not.

The switches S1 to SI have a strange interlocking relationship so that they can be simultaneously switched to terminals a, b, or C by operation.

Next, the operation will be explained. Switches S and ~SS are terminals a
By switching to terminal K, NT8C (4,43MHz) is selected, and by switching to terminal C, NTSC (358MHI5) is selected.

Now, when the switches S1 to Ss are switched to terminal a, one of the tick-off circuits 2 is opened by the switch S1, and the switch S! The IH delay circuit 10 is inserted into the carrier color signal path □, the PAL hue adjustment circuit 15 is selected by the switch S3, and the switch 84K selects the hue adjustment circuit 15 for the PAL system.
．． 43MHg crystal CR.

is selected, and furthermore, the path from the terminal 22 to the flip-flop 21 is floated from the ground by the switch SsK.

Therefore, from the composite video signal applied to input terminal 1, 4.43
The MHg burst signal and the carrier color signal are sent to the tick-off circuit 2.
The color saturation is automatically adjusted by the ACC loop in that part, and the carrier color signal passes through the chromaticity output circuit 8 and reaches the delay amplifier circuit 9. And PAL matrix 11
Because the IH delay circuit 10 is inserted, carrier color signals of the same phase appear on the ■ side of the coil L and are input to the B-Y demodulation circuit 12, and the 01 of the coil L
A carrier color signal whose phase changes by +90 degrees and -90 degrees appears every 11 KI cycles and is input to the R-Y demodulation circuit 13.

On the other hand, in the burst amplifier circuit 6, the extracted 4.43MH
The burst signal of z is amplified, its phase is adjusted by the FAI and scheme hue adjustment circuit 15, and input to the phase detection circuit 1T. Therefore, in the subcarrier oscillation circuit 18, 4.4
A subcarrier as a continuous wave of 3 MHg and phase matched to the burst signal is generated, and is applied to the BY demodulation circuit 12, where the BY demodulation circuit 12 modulates and outputs the BY color difference signal. It is input to the matrix circuit 14. Also, at this time, the flip-flop 21 is repeatedly inverted and reversed by the horizontal pulse applied to the terminal 22, so
The output causes the PAL switch 19 to switch, so that the subcarrier from the subcarrier oscillation circuit 18 is switched so that its phase is shifted by +90 degrees and -90 degrees, and is added to the R-Y demodulation circuit 13. R
The RY color difference signal is decoded in the -Ya tone circuit 13 and inputted to the I/J box circuit 14. This matrix circuit 14 receives the inputted B-Y signal and the R-Y signal.
The IG-Y signal is regenerated by the signal. In the above, when there is no burst signal, the color killer circuit 20 operates, the chromaticity output circuit B is controlled, and the carrier color signal is not output.

Next busy, when switch 51~SI is switched to terminal bK,
The switch Sz K causes the tick-off circuit 2 to
Then, the IH delay circuit 10 is removed from the line by the switches S and K, the hue adjustment circuit 16 for the NTSC system is selected by the switch ssK, and the 4-bit delay circuit 10 is selected by the switch S4.
．． 43MH! The crystal I is selected as is, and the switch Ss K changes to K so that the horizontal pulse escapes to ground.

Therefore, in this case, the flip-flop 21 is oriented in one direction and the PAL switch 19 is turned at +90 degrees (or -90 degrees).
It maintains the state switched to 0 degree) @ and works as a mere 90 degree fixed phase circuit. Therefore, the 4.43 MHz subcarrier is sent to the B-Y return circuit 12 in synchronization with the burst signal, and to the R-Yll adjustment circuit 13 with a phase shift of +90 degrees (or -90 degrees) with respect to the burst signal. , each joins. The color signal from the chromaticity output circuit 8 is 1. After being amplified by the delay amplification circuit 9, it is coiled and shunted, and sent to the B-Y decoupling circuit 1-2 and the R-Y decoupling circuit 1-2 as carrier color signals of the same phase.
The signals are applied to the demodulation circuit 13, demodulated by ζ, and applied to the matrix circuit 14.

Next, when switches S1 to S are switched to terminal C,
The switch S1 selects the 3.58MHsi tick-off circuit 3, the switch sIK removes the upper 1llH delay circuit 10 from the line, the switch Ss selects the NTSC system hue adjustment circuit 16 as described above, and the switch S4 by 3.58MHa Crystal C
R, is selected, and the switch Ss causes the horizontal pulse to escape to ground as above.

Therefore, in this case, compared to the case where the switches S1 to SS are switched to terminal b@, the difference is that the 3.58 MHz tick-off circuit 3 is selected and the 3.58 MHz crystal CR1 is selected. Everything else is exactly the same.

Note that the switches S1 to Ss described above are not limited to mechanical switches, and may utilize diode switch circuits that perform 0N10FF depending on the level of potential. Also, as is clear from the above explanation, 3.58MH! I
A combination of PAL and 4.43MHsa NTSC is also possible. Before further discussion, it is known that when 'J2 is on the δ side, the IH delay circuit can be shared with the 8ECAM chrominance signal processing circuit by adding a chroma amplification circuit (some circuits).

As explained above, according to the multi-system color signal processing circuit according to the present invention, the common part is reduced to one, and PAL system and NT system
Since different parts are switched depending on the SC method, the circuit configuration is extremely simple and cost-effective compared to the conventional color signal processing circuit, which is completed for each method and uses nine circuits. It has characteristics.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional color signal processing circuit including PAL and NTSC systems, and FIG. 2 is a circuit diagram of an embodiment of the same circuit according to the present invention. 10 Patent Applicant: General Co., Ltd.

Claims (1)

[Claims] (1) NTSC system and PA with different 0 color subcarrier frequencies
In a multi-scheme color television receiver FI having a function of selectively processing color signals of at least two systems including the L system, at least a chroma input circuit, a hue adjustment circuit, and an IH delay circuit to be connected to one color signal processing circuit. , a reference carrier wave oscillation circuit, and a PAL switch non-operation circuit, each of which is configured to switch according to a received signal format.