JPS5914951B2 - color television receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Some color television receivers are designed to perform automatic color level adjustment and automatic hue correction using a so-called VIR signal inserted into a received signal.

The VIR signal is inserted into the 19th horizontal section of each vertical section, and has a subcarrier frequency of 3.58 MH.
2 sine wave signal, which is inserted in the same phase as the burst signal.

That is, in FIG. 1, 10T19 indicates the 19th horizontal section, PH is the horizontal synchronization signal, SB is the burst signal, and Sv is the VIR signal. Then, while the burst signal SB is inserted into the black level portion, V
The IR signal Sv is inserted into the gray level part, and this
5, when phase distortion occurs in the carrier color signal, VIR
Similar phase distortion will occur in the signal Sv as well. Therefore,
The phase shift of the VIR signal Sv with respect to the burst signal SB becomes phase distortion of the carrier color signal. Therefore, if, for example, the demodulation axis is controlled in accordance with this deviation, the hue deviation due to phase distortion can be corrected. Furthermore, since the amplitude of the VIR signal Sv corresponds to the level of the carrier color signal, the color level can be made constant by controlling this amplitude to be constant. ■5 However, when the playback signal from the recorder/player is received by such a color television receiver, the recorder/player has a delay circuit of one horizontal period in the color signal system of its recording system or playback system. If the filter has a comb-shaped filter with

An example of a recording system having a comb-shaped filter is one in which a comb-shaped filter is used to separate a luminance signal and a carrier color signal, as shown in FIG. 35 That is, a so-called Y-shaped comb filter 4 is constituted by a delay circuit 2 that delays the original color video signal supplied to the input terminal 1 by one horizontal period and an adder 3, from which a luminance signal is extracted. This is FM-modulated by an FM modulator 5 and supplied to a synthesizer 6. On the other hand, a so-called C-shaped comb filter 8 is configured by a delay circuit 2 and a subtracter 7, from which a carrier color signal is extracted. , this is frequency-converted to the lower frequency side by the frequency converter 9, the converted signal is supplied to the synthesizer 6, and the output signal of the synthesizer 6 is supplied to the heads HA and HB via the recording amplifier 10 and recorded. Ru.

Here, the carrier color signal obtained from the comb filter 8 is
The original carrier color signal is C.

, which is delayed by the delay circuit 2C0-CD as C
If D? The subcarrier frequency Fs (3.58M
Hz) is selected in a relationship of + line offset, and the signal content in adjacent horizontal sections is almost the same, so signal C.

is signal C. It can be considered to be equivalent to the phase-inverted version of . However, when the recording system includes the comb filter 8, the VIR signal in the 19th horizontal interval Tl9 in the recorded signal, and hence in the reproduced signal, has a phase similar to that of the carrier color signal as described above. The relationship between the amplitude and the level of the carrier color signal no longer corresponds to that of the carrier color signal, and the amplitude no longer corresponds to the level of the carrier color signal.

For example, as shown in FIG. 1, a color bar signal S is added to the 18th horizontal section Tl8 in the original signal.

When B is inserted, a composite of the VIR signal Sv and this color bar signal SCB appears in the 19th horizontal section Tl9 of the reproduced signal, and the phase and amplitude are the same as the original VIR signal Sv. becomes something completely different. Furthermore, as shown in FIG. 2, even when no color subcarrier component other than the burst signal SB is inserted into the 18th horizontal section Tl8 of the original signal, the amplitude becomes + of the original VIR signal S. I end up. Therefore, such a reproduced signal is supplied to the above-mentioned color television receiver, and the first
Due to the color subcarrier component of the ninth horizontal section Tl9, when the color level is automatically adjusted or the hue is automatically corrected as described above, the correct adjustment or correction is not performed as when receiving broadcast waves as they are. I get used to it.

Therefore, when receiving a playback signal from such a recording/playback device, it is preferable that the correction circuit based on the VIR signal does not work.

The same applies to a recording/playback device having a comb filter in the color signal system of the playback system.

As a device having a comb filter in the reproducing system, there is one that uses a special high-density recording/reproducing method already proposed by the present applicant.

As shown in FIG. 4A, there are two p
When recording and reproducing fields alternately using the rotating magnetic heads HA and HB, as shown in FIG. Make the corners different from each other.

During recording, the luminance signal is FM-modulated and the carrier color signal is frequency-converted to the lower frequency side. Carrier frequency C of carrier color signal CA of TA and head HB
The carrier frequencies FB of the carrier color signals CB of the tracks TB formed by the above are selected in such a manner that they interleaf each other in frequency.

During reproduction, as shown in FIG. 7, the reproduced output from the heads HA and HB is supplied to a high-pass filter 14 through a reproduction amplifier 13 to extract an FM-modulated luminance signal, which is then demodulated through a limiter 15. The demodulated luminance signal is supplied to a synthesizer 17.

The reproduced output is also supplied to a low-pass filter 18 to take out the low-pass converted carrier color signal CA to C3, which is supplied to a frequency converter 19, and is formed by pulses indicating the rotational phase of the heads HA and H3. Switching signal S. Therefore, when the head HA reproduces the track TA, the switch circuit 20 is switched to the state shown in the figure, and the frequency converter 19 receives F.
When the head HB reproduces the track TB by supplying a frequency conversion signal with a frequency of 8+FA, the switch circuit 2
0 to the state opposite to that shown in the figure, and the frequency converter 19
A frequency conversion signal having a frequency of Fs+FB is supplied to. The output signal of the frequency converter 19 is then filtered through a C-shaped comb filter 2 consisting of a one-horizontal period delay circuit 21 and a subtracter 22.
3, and its output signal is supplied to the synthesizer 17, and a reproduced color video signal is obtained at the output terminal 24. When using this method, as shown in FIG. 5, even if no so-called guard band is provided between adjacent tracks, crosstalk is significantly reduced and long-time recording can therefore be achieved.

That is, since the luminance signal is recorded as an FM modulation signal and has a high frequency, crosstalk is significantly reduced due to so-called azimuth loss.

Regarding the carrier color signal, when the head HA scans the track TA, the output of the filter 18 is the signal CB mixed in as a crosstalk component with respect to the signal CA, as shown in FIG. 6C. , frequency converter 19
When the frequency is converted by a signal with a frequency of F, +FA, as shown in E of the same figure, a crosstalk component with a frequency interleaf relationship with the original signal CSA of a carrier frequency of F8, shown by a broken line, is generated. You will get something mixed with. On the other hand, when the head HB scans the track T3, the output of the filter 18 is the signal C, as shown in FIG.
When the signal CA is mixed into B as a crosstalk component and is frequency-converted by the frequency converter 19 using a signal with a frequency of Fs+FB, as shown in F of the same figure, the signal CA is mixed in as a crosstalk component. A mixture of crosstalk components having a frequency interleaf relationship with the signal CSB shown by the broken line is obtained. Therefore, as shown in FIG. G, most of the crosstalk components are removed by the comb filter 23. Therefore, a reproduced color video signal without crosstalk is obtained at the output end 24. In this way, the recording/playback machine having the comb filter 23 in the color signal system of the reproduction system also has the same problem as the recorder/player having the comb filter 8 in the color signal system of the recording system as shown in FIG. Therefore, it is preferable that the color television receiver's VIR signal-based correction circuit not operate.

In view of this point, the present invention uses a burst signal in a received signal to determine whether the received signal is a playback signal of a recording/playback machine having a comb filter in the color signal system of the recording system or playback system as described above. If the signal is a playback signal of such a recorder/player, the above-mentioned correction circuit based on the VIR signal does not work.

A specific example will be explained below with reference to FIGS. 8 and 9.

In FIG. 8, 31 is an antenna, 32 is a distributor, 33
34 is a video intermediate frequency amplification circuit, and 35 is a video detection circuit.

Reference numeral 100 denotes a recording and reproducing machine which has a built-in tube and is capable of receiving and recording a desired station and also reproducing what has been recorded.

In this recording/reproducing device 100, a special recording/reproducing method such as that described above is used, and a comb filter 23 is inserted in the color signal system of the color signal system. 36
is a changeover switch, which is switched to the contact A side when receiving broadcast waves as is, and switched to the contact V side when the recording/reproducing device 100 is placed in a playback state and a playback signal from this is to be received.

37 is a video amplifier from which a luminance signal is supplied to a matrix circuit 38.

A band amplifier 39 supplies the carrier color signal to a demodulation circuit 41 through a color level adjustment circuit 40.

42 is a gate circuit for the burst signal, and the burst signal from this gate circuit. The signal is supplied to a ringing filter 43 to be converted into a continuous wave signal, and is supplied to this continuous wave signal force oscillator 44,
The oscillation signal is supplied to the phase shift circuit 45, from which R-
Y-axis and BY-axis demodulation signals are supplied to a demodulation circuit 41 .

Red and blue color difference signals are obtained from the demodulation circuit 41 and supplied to the matrix circuit 38, and red, green and blue color signals are obtained from the matrix circuit 38 and supplied to the color cathode ray tube.

The continuous wave signal from the ringing filter 43 is supplied to a detection circuit 46 for amplitude detection, and the detection output is supplied to a band amplifier 39 to control the level of the carrier color signal.

On the other hand, the output signal of the switch 36 is transmitted to the synchronization signal separation circuit 47.
A horizontal synchronizing signal PH and a vertical synchronizing signal Pv are taken out.

These signals PlI and Pv are connected to the gate pulse forming circuit 48.
A gate pulse PG that becomes "1" is obtained during the insertion period of the VIR signal in the 19th horizontal section Tl of each of the above-mentioned vertical sections.Then, this gate pulse PG is supplied to the sampling and hold circuit 49. Of the demodulated voltage on the RY axis obtained from the demodulation circuit 41, the voltage during the insertion period of the 1R signal is extracted and held for one vertical period, and the voltage is applied to one input terminal of the switch circuit 50. Supplied.

The other input terminal of the switch circuit 50 is supplied with a voltage El[ obtained from the mover of the variable resistor 51. The output voltage of this switch circuit 50 is then supplied to the phase shift circuit 45, and the amount of phase shift in the phase shift circuit 45 is controlled according to the voltage. On the other hand, the gate pulse PG is supplied to the sampling hold circuit 52, and the B obtained from the demodulation circuit 41 is
- Of the demodulated voltage on the Y axis, the voltage during the insertion period of the VIR signal is extracted and held for one vertical period,
This voltage is supplied to one input terminal of the switch circuit 53.

The other input terminal of the switch circuit 53 receives a voltage E obtained from the mover of the variable resistor 54. is supplied. The output voltage of this switch circuit 53 is then applied to the color level adjustment circuit 4.
0, and the level of the carrier color signal supplied to the demodulation circuit 41 is controlled according to the voltage. The horizontal synchronization signal PH and the vertical synchronization signal Pv are further supplied to another gate pulse forming circuit 55. As a result, a gate pulse PB that becomes "1" in the burst signal insertion period of the 10th horizontal section TlO of each vertical section is obtained.

This gate pulse PB is then supplied to the gate circuit 56, and of the burst signals obtained from the gate circuit 42, that in the tenth horizontal interval TlO of each vertical interval is extracted.

The extracted burst signal is supplied to the amplitude detection circuit 57 and subjected to amplitude detection, and the detected output is sent to the level detection circuit 58.
supplied to The output of this level detection circuit 58 is supplied to the set side of a flip-flop circuit 59. A vertical synchronizing signal Pv is supplied to the flip-flop circuit 59 on the reset side. The output of the flip-flop circuit 59 is then supplied to a NAND circuit 60. On the other hand, switch 6
1 is provided.

This switch 61 is turned on when performing automatic color level adjustment and automatic hue correction using the VIR signal, and turned off when performing manual color level adjustment and hue adjustment. This switch 61 is connected between an inverter 62 and ground, and the output of the inverter 62 is supplied to a NAND circuit 60.The output of the NAND circuit 60 is then supplied to the switch circuits 50 and 53 as a switching signal.

When switching the changeover switch 36 to the contact A side and receiving broadcast waves as is, when turning on the switch 61,
The output of the inverter 62 becomes "1". The video signal obtained from the switch 36 at this time is in a state as shown in FIG.
2, a burst signal SB of constant amplitude is obtained. The burst signal SBH in the 10th horizontal section TlO is extracted from the gate circuit 56, and the amplitude detection circuit 57 generates a detection output DH of a certain level or higher, as shown in FIG.
is obtained. Therefore, this 10th horizontal section TlO
At the time of the burst signal SBH, the output of the level detection circuit 58 is inverted from one state to another state, and a set signal is supplied to the flip-flop circuit 59, which activates the flip-flop set by the previous vertical synchronization signal P. circuit 5
9 enters the set state in this 10th horizontal section TlO, and its output is inverted from "0" to "1". Therefore, since the output of the inverter 62 is "1", the NAND circuit 6
The output of 0 becomes "O", and both switch circuits 53 and 50 are switched to a state opposite to that shown in the figure. Therefore, the output voltages of the sampling and holding circuits 52 and 49 are supplied to the color level adjustment circuit 40 and the phase shift circuit 45 through the switch circuits 53 and 50, respectively, and inserted into the 19th horizontal section Tl9 as described above. VI
Based on the R signal Sv, automatic color level adjustment and automatic hue correction are performed.

At this time, the output VH in FIG. 9B is the VIR signal Svf)B
- This indicates that the demodulated output on the Y axis is at a constant level. When turning off the switch 61, turn off the inverter 6
The output of NAND circuit 60 becomes "o", and therefore the output of NAND circuit 60 becomes "1", and both switch circuits 53 and 50 are switched to the state shown in the figure.

Therefore, the voltage EO obtained from variable resistors 54 and 51
and ElI are supplied to the color level adjustment circuit 40 and phase shift circuit 45 through the switch circuits 53 and 50, respectively. Therefore, the voltage E. By changing the voltage EH, the color level can be adjusted, and by changing the voltage EH, the hue can be adjusted. On the other hand, when switching the changeover switch 36 to the contact side to receive a playback signal from the recording/playback device 100, the recording/playback device 100 has a comb-shaped filter in the color signal system of the recording system or the playback system as described above. When this is the case, the video signal obtained from the switch 36 is as shown in FIG.
The state is such that the burst signal SBL in the 10th horizontal interval TlO taken out from the gate circuit 56 has an amplitude equal to that of the burst signal SB in the 11th and subsequent horizontal intervals.
It becomes + of that of . Therefore, the amplitude detection circuit 57 outputs a detection output DL below a certain level, as shown in FIG.
is obtained. Therefore, this 10th horizontal section TlO
At the time of the burst signal S3L, the output of the level detection circuit 58 becomes one state, and no set signal is supplied to the flip-flop circuit 59, and the flip-flop circuit 59, which was reset by the previous vertical synchronization signal Pv, remains unchanged. The set state is maintained and its output remains at "O". Therefore, even if the switch 61 is turned on and the output of the inverter 62 is "1", the output of the NAND circuit 60 is "1", and both the switch circuits 53 and 50 are switched to the state shown in the figure. Therefore, at this time, the voltage E obtained from the variable resistors 54 and 51. and E1[
is supplied to the color level adjustment circuit 40 and phase shift circuit 45 through switch circuits 53 and 50, respectively, and the voltage E
. The color level can be adjusted by changing the voltage E.
By changing H, it becomes possible to adjust the hue. That is, at this time, the correction circuit based on the VIR signal is automatically brought into a non-operating state.

At this time, the output VL in FIG.
This shows that the demodulated output on the axis also becomes a + level.
As described above, according to the receiver of the present invention, it is possible to dynamically determine whether the received signal is a reproduced signal from a recording/reproducing device having a comb-shaped filter in the color signal system by a burst signal in the received signal. The correction circuit based on the VIR signal does not work when the signal is played back from such a recording/playback device, so incorrect adjustments or corrections may be made due to the fact that the VIR signal is not a genuine one. There are no inconveniences.

[Brief explanation of the drawing]

Figures 1 and 2 are waveform diagrams for explaining the VIR signal,
Figure 3 shows a recording/playback device 0 that has a comb filter in its recording system.
An example system diagram, FIGS. 4 to 7, is for explaining an example of a recording/playback machine having a comb filter in the playback system.
FIG. 4 is a diagram showing the arrangement of the rotating magnetic head and the state of the magnetic gap, FIG. 5 is a diagram showing the recording pattern on the tape, FIG. 6 is a spectrum diagram for explaining the recording and reproducing method, and FIG.
The figure is a system diagram of Isshiki 1 of the reproduction system, FIG. 8 is a system diagram of an example of a color television receiver according to the present invention, and FIG. 9 is a waveform diagram for explaining the same. 39 is a band amplifier, 40 is a color level adjustment circuit, 41
4 is a demodulation circuit, 42 is a burst signal gate circuit, 44 is an oscillator, 45 is a phase shift circuit, 47 is a synchronization signal separation circuit, 4
8 and 55 are gate pulse forming circuits, 49 and 52 are sampling and holding circuits, 56 are gate circuits, 57 are amplitude detection circuits, 58 are level detection circuits, 59 are flip-flop circuits, 100 are recording/reproducing devices, 8 and 23 are comb-shaped It's a filter.

Claims (1)

[Claims] 1. Can receive the playback signal of the recording/playback device, and is based on a reference signal consisting of a subcarrier component having a DC level closer to the white level than the burst signal, which is inserted into a predetermined horizontal scanning section of the video signal in the received signal. In devices equipped with a correction circuit, a burst signal in the received signal is used to detect whether the received signal is a playback signal of a recording/playback device having a comb filter in the recording or playback color signal system. The color television receiver is configured such that the correction circuit does not operate when the detected output is a playback signal of a recording/playback device having the comb filter.