JPH0569355B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color television receiver using a beam index type color picture tube.

In a beam index type color picture tube, a single electron beam scans a phosphor screen in which red, green, and blue color phosphor stripes are arranged repeatedly in the horizontal scanning direction. The phosphor stripes are arranged in the horizontal scanning direction, and the index signal obtained by scanning the index phosphor stripes with the electron beam causes the electron beam to scan the red color phosphor stripes. With primary color signals,
The density is modulated using a green primary color signal when scanning a green phosphor stripe, and a blue primary color signal when scanning a blue phosphor stripe.

In this case, one method for arranging the index phosphor stripes is to adjust the pitch of the index phosphor stripes 11 as shown in FIG.
P _I , red, green and blue color phosphor stripes R, G
Similarly to the pitch P _T of the pair of index phosphor stripes 11 and B, a method of multiplying the pitch P _I by an integral number is generally considered, and as shown in FIG. A set of pitches of red, green and blue colored phosphor stripes R, G and B.
One possible method is to set it to 2/3 or 4/3 of P _T , generally 3n±1/3 (however, n=0, 1, 2...). In either case, index phosphor stripes 11 are typically located between the red, green and blue color phosphor stripes R, G and B, as shown.

By the way, in a receiver using this beam index type color picture tube, even if color synchronization is achieved using the index signal as described above, the color synchronization is not performed accurately, and errors in the hue of the reproduced image occur. Put it away.

The first reason for this is that the phase of the index signal changes due to the cathode drive signal of the picture tube, that is, the density modulation signal of the electron beam. That is, assuming that the diameter of the electron beam is zero, and looking at the amount of excitation and therefore the amount of light emission when the index phosphor stripe 11 is excited by the electron beam, as shown in FIG. If the beam current is constant when the beam crosses stripe 11, the amount of excitation is equal to stripe 1
It is constant within a width of 1 and therefore does not cause a phase change in the index signal. However, as shown in FIG.
When the beam current gradually increases as it traverses the stripe 11, the amount of excitation changes as shown in the figure within the width of the stripe 11, acting to delay the phase of the index signal as shown by the arrow. vice versa,
As shown in Figure C, the electron beam is in stripe 1.
When the beam current gradually decreases as it crosses the stripe 11, the amount of excitation changes as shown in the figure within the width of the stripe 11, acting to advance the phase of the index signal as shown by the arrow. In reality, the electron beam has a certain diameter, but it is still the same. The phase change of the index signal caused by this cathode drive signal becomes noticeable when a highly saturated color is reproduced.

When the index phosphor stripes 11 are arranged as shown in FIG. 2 or 3, such phase changes in the index signal can be reduced, but they cannot be completely eliminated.

Another reason is that there is a time delay between the detection of the index signal and the time when the cathode drive is controlled via the processing circuit. This time delay causes a phase shift when the frequency of the index signal changes. Therefore, if the scanning speed of the electron beam differs depending on the location, there will be an inconvenience that the hue of the reproduced image will differ depending on the location.

The present invention eliminates the above-mentioned drawbacks, ensures accurate color synchronization, and eliminates hue errors in reproduced images.

In this invention, as shown in FIG. 5, a recess is provided in the waveform of the beam current, that is, the cathode current _IK , where the electron beam scans the index phosphor stripe 11. As shown,
Recesses may be provided where the electron beam scans between the red, green and blue color phosphor stripes R, G and B.

In this way, negative feedback control is performed so that when the phase of the index signal is delayed, it is advanced, and conversely, when the phase of the index signal is advanced, it is delayed, so that the index signal is always in the correct phase.

That is, in this case, assuming that the diameter of the electron beam is zero, when the index phosphor stripe 11 is excited by the electron beam, what happens to the amount of excitation and therefore the amount of light emission is as follows.
As shown in Figure A, the index signal is in the correct phase and the concavity of the beam current waveform is aligned with stripe 1.
1, the amount of excitation is consistent within the width of the stripe 11 and does not cause a phase change in the index signal.

On the other hand, as shown in FIG. B, when the phase of the index signal advances and the concave portion of the beam current waveform shifts in the direction in which it advances with respect to the stripe 11,
The amount of excitation is shifted within the width of the stripe 11 as shown in the figure, and acts to delay the phase of the index signal as shown by the arrow. Conversely, as shown in Figure C, when the phase of the index signal lags and the concave portion of the beam current waveform lags behind stripe 11, the excitation amount becomes smaller than that of stripe 1.
It acts to shift the phase of the index signal within a width of 1 as shown in the figure and to advance the phase of the index signal as shown by the arrow. In reality, the electron beam has a certain diameter, but it is still the same.

According to the present invention, the index signal is always set to the correct phase through negative feedback control, so that color synchronization is performed accurately and errors in hue of reproduced images are eliminated.

FIG. 7 shows a specific example of a color television receiver according to the present invention, in which numeral 4 represents a beam index type color picture tube, which is constructed as shown in FIG. 9 as an example.

That is, on the inner surface of the panel, red, green, and blue color phosphor stripes R, G, and B are sequentially and repeatedly arranged in the horizontal scanning direction to form the effective screen portion 6.
In this case, a black material 7 such as carbon is formed between the color phosphor stripes R, G, and B and around the effective screen portion 6, and an aluminum metal back 8 is formed over the entire surface. Index phosphor stripes 11 are arranged in the horizontal scanning direction on the metal bag 8 over the effective screen area 6 and the horizontal scanning start area 9 on one side thereof, and red, green, and blue color phosphor stripes R, It is formed by, for example, 2/3 of the pitch of a pair of pitches of G and B. However, in particular, at the boundary between the effective screen area 6 and the horizontal scanning start area 9, for example, one index phosphor stripe is missing as shown by an arrow 12. Note that the index phosphor stripe 11
are provided at positions between the red, green and blue color phosphor stripes R, G and B.

In the funnel portion of the color picture tube 4, an electron beam 14 is directed to an index phosphor stripe 11.
Lens 1 that receives light 15 emitted when scanning
6 is attached, and a photoelectric converter 17 is attached to the outside thereof.
will be arranged.

Then, the horizontal synchronizing signal P _H (G in Figure 9) is supplied to the monostable multivibrator 21 to obtain a pulse M ₁ (P in the same figure) with a constant pulse width.
At the trailing edge of _M1 , the flip-flop circuit 22 is set, one output signal _F1 (Q in the figure) becomes "1", the other output signal ₁ (R in the figure) becomes "0", and the output signal F1 becomes "1". ₁ becomes "1", the gate circuit 31 opens, and a DC voltage of a value adjusted in advance by the variable resistor 32 passes through the amplifier 33 to the tube 4.
The electron beam 1 is supplied to the first grid 18 of
4 scans the index phosphor stripe 11 of the horizontal scanning start section 9 with a constant beam intensity, and the photoelectric converter 17 outputs an index signal S _I (A in the same figure).
is obtained.

This index signal S _I is supplied to a bandpass filter 41 to obtain a signal S _D (FIG. 9B) having a fundamental frequency corresponding to the pitch of the index phosphor stripe 11. And this signal S _D
is supplied to the PLL circuit 43, synchronized with the signal S _D ,
And a pulse with a frequency twice that of this signal S _D
S _L (D in the same figure) is obtained. That is, the frequency of the oscillation pulse of the VCO 44 is divided into 1/2 by the frequency divider 45, the frequency-divided pulse is phased by the phase shifter 46 for phase adjustment, and the phased frequency-divided pulse and the signal are separated by the phase comparator 47. S _D is phase-compared, and the comparison error voltage is supplied to the VCO 44 through a low-pass filter 48, and a pulse S _L is obtained from the VCO 44. This pulse S _L is then supplied to the frequency dividing circuit 60.

On the other hand, the index signal S _I is
is supplied to the index pulse S _P (C in the same figure)
is obtained. Here, one index pulse _SP is missing at a location corresponding to the missing portion 12 of the index phosphor stripe at the boundary between the horizontal scanning start portion 9 and the effective screen portion 6 described above.

This index pulse S _P is then supplied to a retrigger type monostable multivibrator 51, which is triggered at the rising edge of the index pulse S P. The time τ for maintaining the metastable state of the monostable multivibrator 51 is made somewhat larger than one period of the index pulse _SP . Therefore, the output signal S _R (Fig. 9E) of this monostable multivibrator 51 is:
For example, while the index pulse S _P is obtained at a predetermined period, the state of "1" is maintained, and if one index pulse S _P is missing at the above-mentioned missing portion 12, the immediately preceding index pulse is It is reversed to "0" after a time τ has elapsed from the rise indicated by the arrow of S _P. Then, when the electron beam 14 scans the index phosphor stripe 11 on the effective screen section 6 and the index pulse S _P is again obtained at a predetermined period, it becomes "1" again.

This output signal S _R is the monostable multivibrator 5
2, and a pulse S _M (FIG. 9F) having a pulse width necessary for timing adjustment is obtained from the falling edge indicated by the arrow.

However, if the index signal S _I becomes missing in the middle of the effective screen section 6, the output signal S _R of the retrigger type monostable multivibrator 51 becomes "0".
The pulse S _M can now be obtained from the monostable multivibrator 52 even at this missing point.

Therefore, this monostable multivibrator 52
The pulse S _M from is supplied to the AND circuit 53,
On the other hand, the horizontal synchronizing signal P _H (FIG. 9, G) is supplied to the monostable multivibrator 54 to obtain a pulse M ₂ (FIG. 9, H) with a constant pulse width, and the trailing edge of this pulse M ₂ is applied to the flip-flop circuit 55. is set and its output signal F ₂ (I in the same figure) becomes "1" in the middle of the horizontal scanning start section 9, and the flip-flop circuit 55 is activated at the trailing edge of the pulse _SM from the monostable multivibrator 52, as indicated by the arrow. The output signal F ₂ becomes "0" after being reset, and this output signal F ₂ is supplied to the AND circuit 53, and only that in the missing portion 12 of the pulse _SM is detected as the detection pulse S _MG (J in the same figure). )
obtained as.

Then, this detection pulse S _MG is supplied to the frequency dividing circuit 60, and in a state regulated by this detection pulse S _MG , the output signal S _L of the PLL circuit 43 is divided into 1/3, and 120 Different reds,
Green and blue splitting pulses F _R , F _G and F _B are obtained.

That is, the frequency divider circuit 60 includes, for example, a three-stage JK flip-flop circuit 61 as shown in FIG.
The circuit 61 is preset, its Q output F _R (K in Figure 9) becomes "1", and the circuits 62 and 63 are cleared in the interval of the pulse width of the pulse S _MG . Then, the respective Q outputs F _G and F _B (M and O in the figure) are set to "0". Then, at the first falling edge of the signal S _L after the pulse S _MG , each output is shifted and connected to the circuit 61.
The Q output F _R of the circuit 62 is "0", the Q output F _G of the circuit 62 is "1", and the Q output F _B of the circuit 63 is "0". At the next falling edge of signal S _L , the Q output of circuit 61
F _R is "0", Q output F _G of circuit 62 is "0", and Q output F _B of circuit 63 is "1". And the signal
At the next fall of S _L , the state is the same as the first state, that is, the Q output F _R of the circuit 61 is "1",
Q output F _G of circuit 62 is “0”, Q output of circuit 63
F _B becomes "0" and the above operation is repeated from then on.

Therefore, the JK flip-flop circuit 61,
The Q outputs F _R , F _G and F _B of 62 and 63 are "1" during the period during which the electron beam 14 scans the red, green and blue color phosphor stripes R, G and B of the effective screen area 6, respectively. becomes.

The dividing pulses F _R , F _G and F _B are supplied to AND circuits 71, 72 and 73, while the flip-flop circuit 22 is reset at the trailing edge of the pulse _SM from the monostable multivibrator 52, and its output is Signal F ₁ (Q in Figure 9) is "0", output signal ₁
(R in the same figure) becomes "1", and the division pulses F _R , F _G
and F _B , when this output signal ₁ becomes "1", pulses G _R , G _G and G _B ( S, T, and U) in the same figure. And these pulses G _R , G _G and G _B
are monostable multivibrators 81, 82 and 83
gate signals H _R , H _G and H _B (V,
W and X) are obtained.

_{Then ,} the gate circuits 34, ₃₅ are
and 36 are opened and red, green and blue primary color signals E _R ,
E _G and E _B are supplied to the first grid 18 of the tube 4 through an amplifier 33.

Therefore, when the electron beam 14 scans the red color phosphor stripe R, the electron beam 14 receives the red primary color signal E _R
When scanning the green phosphor stripe G, the green primary color signal _E is used to scan the blue phosphor stripe B.
When scanning, the blue primary color signal E _B is density-modulated.

In the present invention, a gate signal is applied at the point where the electron beam 14 scans between the red, green, and blue color phosphor stripes R, G, and B of the effective screen portion 6.
H _R , H _G and H _B (V, W and X in Figure 9) all become "0" and the gate circuits 34, 35 and 36
and all gate circuits 31 are closed. Since the input side of the amplifier 33 is grounded via the resistor 90, when all the gate circuits 34 to 36 and 31 are closed in this way,
The input signal to the first grid 18 of tube 4 is zero.

Therefore, the cathode current I _K of tube 4 (Y in the same figure)
In the waveform shown in FIG.
A recess is formed where the space is scanned.

The example shown in the figure is a case where a missing part 12 of the index phosphor stripe is provided at the boundary between the horizontal scanning start part 9 and the effective screen part 6, and color synchronization is regulated by detecting this missing part 12. However, the index phosphor stripes 11 may be counted at the horizontal scanning start section 9 without providing the missing section 12, and the color synchronization may be regulated based on the count output. can be applied as is.

Furthermore, as shown in FIG.
As with a set of pitches for the green and blue color phosphor stripes R, G and B, it is also generally applicable to integer multiples.

[Brief explanation of the drawing]

Figures 1 to 3 are diagrams showing a method of arranging index phosphor stripes in a beam index type color picture tube, Figure 4 is a diagram for explaining the purpose of the present invention, and Figure 5 is a diagram showing the invention. FIG. 6 is a diagram for explaining the effects of the present invention; FIG. 7 is a system diagram of an example of a color television receiver according to the present invention; FIG. 8 is a diagram for explaining the state of the cathode current when is a partial system diagram thereof, and FIG. 9 is a waveform diagram for explaining its operation. R, G and B are red, green and blue color phosphor stripes, and 11 is an index phosphor stripe.

Claims (1)

[Scope of Claims] 1 Red, green, and blue color phosphor stripes are arranged repeatedly in the horizontal scanning direction on the inner surface of the panel at intervals, and the red, green, and blue color phosphor stripes are arranged repeatedly at intervals. A beam index type color picture tube in which index phosphor stripes are provided periodically in the horizontal scanning direction so as to be located between the two, and an electron beam of the color picture tube emits the red, green and blue color fluorescent light. When scanning the body stripes, a video signal generation circuit generates red, green, and blue video signals correspondingly and supplies them to the input electrodes of the color image receiver; A color television receiver comprising: a control circuit that controls the video signal generation circuit to prevent generation of a video signal when scanning a position.