JPS5931089Y2 - color television receiver - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a color television receiver capable of receiving two broadcast signals, PAL signals and NTSC signals.

For example, if a videotape recorded with an NTSC VTR is
When played on an AL VTR, the color subcarrier is 4.43MHz.
However, in order to receive this signal on a PAL color television receiver, a color signal circuit that processes the 4.43 MHz NTSC signal is required.

In addition to this example, 3.58 MHz PAL
Since there are some areas where PAL and NTSC signals are broadcast, a color television receiver that can receive both PAL and NTSC signals is desired.

FIG. 1 briefly shows the general configuration of a PAL color signal processing circuit. The carrier color signal obtained by detection from the video intermediate frequency signal is transmitted through first and second bandpass amplifiers 1,
It is amplified by 2.

On the other hand, the burst signal gated by the burst gate circuit 3 acts as a reference signal for phase detection of the oscillation signal of the color subcarrier oscillator 11 in the APC (automatic phase control) phase detector 10. The output serves for phase control of the color subcarrier oscillator 11.

The carrier color signal output from the second bandpass amplifier 2 is I
H (one horizontal period) is supplied to the adder 5 and the subtracter 6 through both the delay line 4 and the non-delay line 4'.

Adder 5 adds the carrier color signals applied through IH delay line 4 and non-delay line A.

As a result, the adder 5 cancels the RY component of the carrier color signal and outputs the BY component with twice the size.

This output is given to the BY demodulator 7 at the next stage.

On the other hand, the subtracter 6 subtracts the carrier color signals applied from the IH delay line 4 and the non-delay line 1, cancels the B-Y component, and doubles the R-Y component (this R-Y (the components are inverted for each IH) is output and supplied to the next stage RY demodulator 8.

The color subcarrier generated by the color subcarrier oscillator 11 is 90
The signal is supplied to the B-Y demodulator 7 through the degree phase shifter 12, and is also supplied to the R-Y demodulator 8 through the PAL switch 13, which switches 180 degrees every IH.

The PAL switch 13 is connected to the modulation axis of the R-Y component whose modulation axis is inverted for each line among the components of the PAL carrier color signal, and the demodulation axis in the R-Y demodulator 8 [color subcarrier oscillator 11 This switch is used to align the phase with the carrier wave] and is essential in standard PAL color television receivers.

B-Y demodulated by B-Y demodulator 7 and R-Y demodulator 8,
The R-Y color difference signal is used by the matrix circuit 9 to create a G-Y color difference signal and is output individually.

In contrast to the PAL color signal circuit shown in FIG. 1, the NTSC color signal processing circuit corresponds to a circuit in which the IH delay line 4, adder 5, subtracter 6, and PAL switch 13 are removed.

However, when receiving NTSC, delay line 4 and non-delay line l
The adder 5 and the subtracter 6 may be used as they are if the signal is not transmitted through one of them, and there is no problem even if the delay line 4 is operated.

In addition to that, if you make a provision to disable the PAL switch 13 when receiving NTSC, the circuit in Figure 1 will be NTSC.
It can also be used for color signal processing.

In this way, a color signal processing circuit that can be used for both PAL and NTSC can be realized, but in NTSC broadcasting, compared to PAL broadcasting, there are no differences in hue between broadcasting stations, and there is no hue distortion in signals reproduced from a VTR. A special hue adjustment circuit is required.

In view of this, the present invention provides PAL processing with one color signal processing circuit.
This is a color television receiver capable of processing both NTSC and NTSC signals and is provided with a suitable hue adjustment circuit, and will be described in detail below according to an embodiment shown in the drawings.

In FIG. 2, the same parts as in FIG. 1 are given the same symbols for convenience of explanation, and 14 is a hue adjustment circuit provided in accordance with the present invention, and in the case shown, especially a burst gate circuit. 3 to the APC phase detector 10 by changing the phase of the burst signal and following the color subcarrier oscillator 1.
Although the hue is adjusted by changing the output phase of the color subcarrier 11, it goes without saying that the hue adjustment circuit 14 may be provided on the output side of the color subcarrier oscillator 11.

The hue adjustment circuit 14 is a PAL portion 15 consisting of a semi-fixed adjustment volume VR1 and an inductance coil L1.
, an NTSC section 16 consisting of a capacitor C3, a variable inductance LV, an inductance coil L2, and a variable adjustment volume R2, a resistor R1, and a capacitor C1.
, C2, and the PAL external portion 15 and the TSC portion 16 are selectively switched by a switch SW.

The resistor R1 and capacitor C1 of the common portion 17 are related to phase shift, but the capacitor C2 merely functions as a direct current cut.

The semi-fixed adjustment volume (R1) in the PAL external portion 15 is useful in setting an appropriate phase position during the adjustment process during production at the factory.

On the other hand, the variable adjustment volume ■R in the NTSC section 16
2 is meaningful in allowing viewers to eliminate differences in hue between NTSC broadcasting stations and deviations in hue reproduced from a VTR by adjustment.

Therefore, it is desirable that the adjustment knob of the variable adjustment volume vR2 protrudes toward the front side of the receiver.

The variable inductance Lv in the NTSC section 16 is used for the same purpose as the fixed adjustment volume R1 in the PAL external section 15, and therefore it should be installed in a place where it cannot be adjusted by the viewer. .

In the hue adjustment circuit 14 of FIG. 2, the capacitor C4 is a mere coupling capacitor and is not related to phase shift.

The specific numerical values of each element are R1=33 (1, C1=1
50PF, L1=L2=8.2μH, C5-150PF
can be mentioned.

The switch SW is driven by the output of a detection circuit that detects whether a PAL signal or an NTSC signal is being received, and a specific implementation configuration thereof is shown in FIG.

Reference numeral 18 denotes a relay body, which brings the contact piece 19 into contact with the contact 20 side when current flows through the relay coil L3.

22 is a received signal detection circuit, and the number of synchronization signals is PAL.
Note that there is a difference between 625 and 525 for NTSC, and □If the number of synchronization signals is 625, O■
When there are 525 lines, a DC output of +12V is generated.

Therefore, in the case of PAL reception, the transistor Tr remains off, and no current flows through the relay coil L3, so the contact piece 19 is in contact with the contact 20, and the PAL
The external part 15 works for phase adjustment, and the part 16 for NTSC is separated.

On the other hand, in the case of NTSC reception, the +12V voltage generated in the detection circuit 22 is divided by resistors R2 and R3 and applied to the base of the transistor Tr.
Since r is turned on, relay coil L3 is connected from terminal 23.
A current flows to the ground through the transistor Tr, and the contact piece 19 comes into contact with the contact 21 side, so that only the NTSC portion 16 works.

Note that the diode D functions as a protection diode to prevent a large voltage from being generated between the terminals 24 and 25 when the current in the relay coil L3 is cut off.

As explained above, according to the present invention, PAL color signals and NTS
In a color signal processing circuit capable of processing C color signals, suitable hue adjustment can be achieved in accordance with each of the signals, which is extremely effective.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a general PAL color signal processing circuit. FIG. 2 is a circuit diagram of a main part of a color television receiver embodying the present invention, and FIG. 3 is a circuit diagram showing a part of FIG. 2 in more detail. 14...Hue adjustment circuit, 15...PA
Part for L, 16... Part for NTSC, 22...
...Detection circuit, SW...Switch, ■R1
・・・・・・Semi-fixed adjustment volume, ■R2・・・・・・
Variable adjustment volume, Lv... (for semi-fixed adjustment)
variable inductance.

Claims (3)

[Scope of utility model registration request] (1) PAL color signal and NTSC in one color signal processing circuit
In a color television receiver capable of processing color signals, a hue adjustment circuit is provided, and the hue adjustment circuit is divided into a PAL portion and an NTSC portion.
The color signal processing circuit is selectively connected to the color signal processing circuit by a switch depending on reception and NTSC reception, and a semi-fixed adjustment means is provided in the PAL portion, and a variable adjustment means is provided in the NTSC portion. A color television receiver. (2) The color television receiver according to claim 1, wherein the switch is driven by the output of a detection circuit that detects whether a PAL signal or an NTSC signal is being received. . (3) The color television receiver according to claim 1, wherein the NTSC portion is also provided with a semi-fixed adjustment means.