JPS6359590B2 - - Google Patents

Description

[Detailed description of the invention]

This invention aims to prevent the vertical amplitude of the screen from changing even if there are high voltage fluctuations in a color television receiver using a beam index type color picture tube. For this purpose, an example of a technique attempted prior to the present invention as a technique using index signals from index stripes is shown in FIG. 1, and will be explained first. In FIG. 1, numeral 10 indicates a beam index type color picture tube, and its screen portion includes:
As shown in FIGS. 2 and 3A (FIG. 3A indicates the beginning of the horizontal scan as indicated by arrow 14 in FIG. 2), red, green, and blue color phosphor stripes R,
An effective screen area 11 is formed in which G and B are repeatedly arranged at a predetermined pitch in the horizontal scanning direction.
Further, in the screen portion, an index area 12 is formed, which overlaps the area 11 and has index phosphor stripes I arranged in the horizontal scanning direction over a wider area than the area 11. In this example, the arrangement pitch of the index stripe I is the color stripe R to B.
It is said to be 2/3 of the repeating pitch of one set of . Further, the electron gun of the picture tube 10 emits a single electron beam, and its horizontal and vertical deflection is performed by horizontal and vertical deflection coils (not shown), as in a normal picture tube. As shown in Figure 2, it covers area 12 and a wider area 13
is the scanning area. Therefore, as shown in FIG. 3B, the falling edge of the horizontal blanking pulse Ph (time t ₂ ) coincides with the boundary of the scanning area 13. Furthermore, a photodetector element 19 for detecting the light emitted from the index stripe I is provided in the funnel portion of the picture tube 10. Then, the horizontal blanking pulse Ph is supplied from the terminal 21 through the OR circuit 22 to the monostable multivibrator 23, and as shown in FIG. 3C, the output becomes "1" as the pulse Ph falls.
Q ₂₃ is taken out. In this case, as will be described later, the multivibrator 23 is cleared at time t ₅ and becomes Q ₂₃ = “0”, but when it is not cleared, the electron beam is transmitted to the area 11 as shown by the chain line in FIG. 3C. A time constant is set so that Q ₂₃ = “0” at time t ₆ when scanning. This signal Q ₂₃ is then supplied as a control signal to the switch circuit 25 through the OR circuit 24, and the switch circuit 25 is turned on when _{Q 23} = “1”.
= “0”, it is turned off. Thus, Q ₂₃ =
During the period t ₂ to _{t 5} in which the voltage is “1”, the DC voltage of the power supply 26 is supplied to the first grid of the electron gun of the picture tube 10 through the switch circuit 25, and the electron beam is made to have a relatively large constant beam amount. . Therefore, time t ₂
Since the electron beam scans the index stripe I from time t3 subsequent to _t3 , the stripe I emits light corresponding to this scanning, so that the pitch of the stripe I changes from time _t3 , as shown in FIG. 3D. An index signal Si having a frequency and phase determined by the scanning speed of the electron beam and the scanning speed of the electron beam is obtained at the detection element 19. Then, this signal Si is passed through the bandpass filter 2.
7 and a phase shift circuit 28, unnecessary components are removed and phase correction is performed, and then the signal is supplied to the PLL 30. In this PLL 30, an oscillation signal S ₃₁ with a free-running frequency twice that of the signal Si is taken out from the VCO 31, this signal S ₃₁ is frequency-divided by 1/2 by the frequency dividing circuit 32, and this frequency-divided signal S ₃₂ and the signal Si is supplied to the phase comparison circuit 33, and its comparison output is supplied to the VCO 31 as a control signal through the low-pass filter 34. Therefore, the VCO 31 oscillates in synchronization with the signal Si, and the oscillation signal S ₃₁ has a constant phase relationship with the signal Si and has a frequency twice that of the signal Si, that is, an arrangement of color stripes R to B. The frequency is three times the so-called triplet frequency, which is determined by the pitch and the scanning speed of the electron beam. In this case, in order to hasten the start of synchronization of the PLL 30 at time _t3 , the following procedure is performed. That is, the pulse Ph from the OR circuit 22 is
The PS flip-flop circuit 41 is supplied as a set input, and the signal Si from the phase correction circuit 28 is supplied as a reset input to the flip-flop circuit 41 through the Schmitt circuit 42, so that at time _t2 , as shown in FIG. 1" and becomes "0" at time _t3 , the output _Q41 is taken out and is supplied to the VCO 31 as an oscillation start/stop control signal through the logic circuit 43, and _Q41 =
When it is "0", it is caused to oscillate and is also supplied to the frequency dividing circuit 32 as a regulation signal for its frequency dividing operation. Therefore, when the PLL 30 starts at time _t3 , the phases of the oscillation signal _S31 and the frequency-divided signal _S32 are regulated to a constant state, so that the PLL 30 immediately locks onto the signal Si at time _t3 . Furthermore, from the multivibrator 23 to FIG.
The output ₂₃ is taken out and supplied to the NOR circuit ₅₁ as shown in FIG.
A signal that becomes “1” at t ₃ and becomes “0” at time t ₅
Q ₅₁ is taken out. This signal ₅₁ is then supplied to the counter 52 as a clear input, and the signal _S32 is supplied to the counter 52 as a count input. Therefore, the counter 52 outputs a signal at time _t3 .
S starts counting ₃₂ , and the count value is
In t ₃

It is [0], but thereafter it increases every cycle of the signal _S32 . At this time, the signal _S32 is synchronized with the signal Si, and since the signal Si corresponds to the index stripe I,
The count value of the counter 52 counts the number of times the electron beam scans the stripe I. Then, at time _t4 , that is, when the counter 52 counts the number of stripes I up to the boundary between areas 12 and 11, the output ₅₂ of the counter 52 changes from "1" to "0" as shown in FIG. 3H. "become. And this signal ₅₂ is the multivibrator 2
3 as a clear input, so the time
At time t ₅ , when the operating speed is slightly slower than t ₄ ,
Q ₂₃ = cleared to “0”. Also, at this time,
Since Q ₂₃ becomes “1”, ₅₁ becomes “0”, and the counter 52 is also cleared and ₅₂ becomes “1”.
Therefore, as shown in FIG. 3C, the signal _Q23 becomes "0" at a time point before the time point _t6 determined by the time constant, that is, at the start time point _t5 of the horizontal scanning of the area 11. Further, the oscillation signal S ₃₁ is transmitted to the gate signal forming circuit 61
A gate signal Sr that is supplied to the input terminal and changes in accordance with the color index R to B as shown in FIG. 3 I to K.
~Sb is formed. Note that at this time, signals ₂₃ ,
Ph is supplied to the logic circuit 43, and its output signal is supplied to the formation circuit 61, so that the phases of the signals Sr-Sb are regulated as shown in FIG. 3I-K. The three primary color signals Er to Eb are extracted from the color demodulation circuit 70 or the matrix circuit 70 and supplied to the gate circuits 62R to 62B, and the gate signals Sr to Sb are supplied to the gate circuits 62R to 62B. When scanning the red color stripe R, the signal Er is taken out from the gate circuit 62R, and the signals Er to Eb are output from the gate circuit 62R.
Among them, a signal corresponding to the color stripe being scanned by the electron beam is extracted, and this signal is supplied to the first grid of the picture tube 10 through a switch circuit 63. Also, at this time, the signal ₅₂ is supplied to the RS flip-flop circuit 64 as a set input, and the pulse Ph from the OR circuit 22 is supplied to the flip-flop circuit 64 as a reset input, so that, as shown in FIG. ₁ , the output Q ₆₄ becomes "0" at the rising edge of the blanking pulse Ph, and becomes "1" at time t ₄ , and this signal Q ₆₄
is supplied to the switch circuit 63 and the output signals of the switch circuits 62R to 62B are blocked during the period t ₁ to t ₄ when Q ₆₄ =“0”. Therefore, since the region 13 of the picture tube 10 is scanned by the electron beam and the density of the electron beam is modulated by the three primary color signals corresponding to the color stripes being scanned, a color image is reproduced. Note that, as shown by the arrow 15 in FIG. 2, when the electron beam is scanning outside the index area 12, the signal Si is not obtained even at time _t3 , so each signal is As shown in Figures A to L. Then, the vertical amplitude of the raster of the picture tube 10 is detected and corrected as follows. In other words, this is the same with ordinary picture tubes, but in picture tube 10, horizontal deflection and vertical deflection are performed at the same time, so when the screen of picture tube 10 is viewed from the user side, all scanning The line is not completely horizontal, but slopes slightly down to the right. Therefore, when the vertical amplitude is the correct size, as shown in FIG. scan line 1 of
The first half of 6 is located in index area 12,
The latter half is outside the index area 12. Also,
If the vertical amplitude is smaller than the normal value, the nth scan line will be located above scan line 16, as shown as straight line 16A in FIG. . Furthermore, when the vertical amplitude is larger than the normal value, the n-th scanning line is set to the scanning line 16 as shown as a straight line 16B.
It is located below the index area 12, and most of it is outside the index area 12. And, as explained in FIGS. 2 and 3,
Since the signal Si is obtained when the electron beam is scanning the index area 12, the time t ₃
A signal Si is obtained over a period t _i from
The size of this period t _i varies depending on the vertical position of the scanning line 16. Therefore, the period t _i will change corresponding to the vertical amplitude. Therefore, in the example shown in FIG. 1, the vertical blanking pulse Pv is transmitted from the terminal 29 to the OR circuit 2.
At the same time, it is supplied to a frequency divider circuit 81 and divided into a pulse Q ₈₁ having a frame period as shown in FIGS. 6A and 6B, and this pulse Q ₈₁ is supplied to a D flip-flop circuit 82 as a clock input. At the same time, a voltage at the "1" level is supplied to the flip-flop circuit 82 as the D input, as shown in FIG.
As shown in FIG. 3, a signal Q ₈₂ which becomes "1" at the rising time T ₀ of the pulse Pv for each frame is extracted. This signal Q ₈₂ is then supplied to the counter 83 as a clear input, and the pulse at the terminal 21
Ph is supplied to an inverter 84 and made into a pulse as shown in FIG. Therefore, the counter 83 changes from the clear state to the count state at time _T0 and starts counting the number of rising pulses. Then, when the count value of the counter 83 reaches [n], that is, the vertical blanking pulse Pv
When the n-th scanning line 16 is reached, it is detected by the AND circuit 85, and therefore, as shown in FIGS. The output Q ₈₅ becomes "1" at the rising time T ₁ of the pulse corresponding to the n-th scanning line 16. This signal Q ₈₅ is then supplied to the D flip-flop circuit 86 as the D input, and the pulse
Ph is supplied as a clock input and its output Q ₈₆
is supplied to flip-flop circuit 82 as a clear input. Therefore, at time T ₂ after a horizontal period from time T ₁ ,
Since Q ₈₆ becomes "0" due to the rise of the pulse Ph, the flip-flop circuit 82 is cleared at time T ₂ and Q ₈₂ becomes "0". And Q ₈₂ =
When it becomes "0", the counter 83 is cleared, so Q ₈₅ becomes "0" from time T ₂ . In addition, at the time
At time T ₃ , one horizontal period after T ₂ , Q ₈₅ = “0”
Therefore, Q ₈₆ becomes “1”. In this way, the output Q ₈₅ of the AND circuit 85 becomes "1" during the horizontal period T ₁ to T ₂ corresponding to the n-th scanning line 16. Then, the signal Si from the Schmitt circuit 42 is supplied to the switch circuit 91, and the signal _Q85 is supplied to the switch circuit 91 as a control signal, and as shown in _{FIG .}
Si, that is, a signal Si whose period t _i changes in accordance with the scanning position of the scanning line 16 is extracted. and,
This signal Si is supplied to a retriggerable type monostable multivibrator 92, and as shown in _{FIG .}
This signal Q ₉₂ is supplied to the integrating circuit 93 and is made into a DC voltage S ₉₃ at a level corresponding to the period t _i ,
This voltage S ₉₃ is supplied to the vertical deflection circuit 100 as an amplitude control signal for the vertical deflection current. That is, for example, the voltage S ₉₃ amplitude-modulates the power supply voltage of the deflection circuit 100, and when the voltage S ₉₃ is large, the vertical deflection current is made larger. Therefore, since the n-th scanning line 16 is always controlled to the position shown in FIG. 5, the vertical amplitude becomes constant. In this way, in the example shown in FIG. 1, the vertical amplitude of the screen can be kept constant even if there are high voltage fluctuations. Moreover, in that case, even if the odd field and even field are shifted by one vertical position of the n-th scanning line 16 due to interlaced scanning,
Since the vertical position of the scanning line 16 is detected for each frame, no error occurs in vertical amplitude control. However, in this example, the edges of the index stripes may not be aligned,
If this is not parallel to the horizontal axis of the cathode ray tube, there is a drawback that it does not work well, and the present invention has also improved this drawback. Embodiments of the present invention will be described below with reference to FIG. In the example shown in FIG. 7, the period during which the electron beam scans the index area 12 is compared with a reference period, and by making the scanning period constant, the vertical amplitude is made constant. That is, in the D flip-flop circuit 111,
The signal Q ₂₃ is supplied as a clock, the "0" level is supplied as the D input, and the signal ₅₁
is supplied as a set direct input from the flip-flop circuit 111, as shown in FIG. 8E (FIG. 8A shows the vertical blanking pulse Pv, and FIGS. ) B, C,
(same as G), the electron beam is in the index area 12
An output Q ₁₁₁ is taken out which becomes "1" at time t ₃ during the scanning period and becomes "0" at the next time t ₂ . This signal Q ₁₁₁ is then supplied to the D flip-flop circuit 112 as a D input, and the signal
_Q23 is supplied as a clock, _and as shown in FIG. At the first time t ₆ after the region 12 is no longer scanned, an output Q ₁₁₂ that becomes "0" is taken out, and an output ₁₁₂ that changes in the opposite way to the output Q ₁₁₂ as shown in FIG. 8G is also taken out. . Therefore, Q ₁₁₂ =
During the period _T12 when the value is “1”, the electron beam is in the region 12.
corresponds to the period during which the . The signals Q ₁₁₂ and ₁₁₂ are shown again in FIGS. 9A and 9B and 10A and 10B. The signals Q ₁₁₂ and ₁₁₂ are then supplied to an AND circuit 113 and a NAND circuit 114. Also, the signal
Q ₁₁₂ is supplied to the retriggerable type monostable multivibrator ₁₁₅ , and as shown in FIG. 9C and FIG. period of
An output Q ₁₁₅ that becomes "0" after T ₁₅ is taken out, and an output ₁₁₅ that changes in the opposite way to the output Q ₁₁₅ is taken out, as shown in FIGS. 9D and 10D, and these signals Q ₁₁₅ , ₁₁₅ is a NAND circuit 114
and is supplied to the AND circuit 113. Therefore, as shown in FIG. 9, the period _T12 during which the electron beam scans the index area 12 is
When it is longer than the reference period T ₁₅ , the output Q ₁₁₃ of the AND circuit 113 becomes “1” during the difference period (T ₁₂ −T ₁₅ ) as shown in FIG. 9E, and as shown in FIG. 9F. The output 114 of the NAND circuit ₁₁₄ remains at "1". Conversely, as shown in FIG.
When T ₁₂ is shorter than the reference period T ₁₅ , _the output Q ₁₁₃ remains “ ₀ ” as shown in _FIG . becomes “0”. Then, the electron beam
The scanning period T ₁₂ directly corresponds to the vertical amplitude of the screen, and the reference period T ₁₅ corresponds to the reference value of the vertical amplitude, so the signal Q ₁₁₃ indicates the increase in vertical amplitude, and the signal ₁₁₄ indicates the decrease. And when Q ₁₁₃ = “1”, this signal
Q ₁₁₃ connects capacitor 11 through diode 116
8, the capacitor 118 is charged by the signal Q ₁₁₃ , and when ₁₁₄ = “0”, this signal
Q ₁₁₄ causes capacitor 118 to become diode 117
is discharged through. And this capacitor 1
18 is supplied to a low-pass filter 119, a DC voltage S ₁₁₉ at a level corresponding to the vertical amplitude of the screen is taken out from the filter 119, and this voltage S ₁₁₉ is supplied to the vertical deflection circuit 100 to adjust the vertical amplitude. is corrected to a constant value. In this way, even in this example, the vertical amplitude of the screen can be kept constant even when high voltage fluctuations occur. Furthermore, in the example of FIG. 7, instead of the period T12 during which the electron beam scans the region ₁₂ , the number of dotted lines scanned over the region 12 may be counted. Additionally, the multivibrator 112 has a signal
Pulse Ph may be used instead of Q ₂₃ . Furthermore, for the horizontal amplitude, e.g. the pulse
The phase of Ph and the signal ₅₁ may be compared, and the power supply voltage of the horizontal deflection circuit may be amplitude-modulated using the comparison output to keep the horizontal amplitude constant.

[Brief explanation of the drawing]

FIG. 1 is an example for explaining the present invention, FIG. 7 is a system diagram of an example of the present invention, and FIGS. 2 to 6 and 8 to 10 are explanatory diagrams thereof. 10 is a picture tube, 30 is a PLL, and 100 is a vertical deflection circuit.

Claims (1)

[Claims] 1. In a color television receiver using a beam index cathode ray tube with index stripes arranged in and around the effective screen, the index area at the bottom edge of the screen and the area outside the index area are determined based on the vertical blanking pulse. A measuring means for measuring the time or number of scanning lines until the beam horizontally scans the boundary, a comparing means for comparing this measured value with a reference value set in advance for each frame, and a vertical amplitude based on this comparative value. A beam index type color television receiver provided with control means for constant control.