JPH06101849B2 - Color image display device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for driving a flat cathode ray tube used for a color television receiver, a terminal display of a computer and the like.

2. Description of the Related Art As a flat cathode ray tube which is a prior art by the present applicant, there is a flat cathode ray tube having a structure shown in FIG. Actually, the structure that each electrode is built in by the vacuum envelope (glass container) is taken,
In the figure, the vacuum envelope is omitted to clarify the internal electrodes. Further, in order to clarify the horizontal and vertical directions of the screen for displaying images, characters, etc., the horizontal direction H and the vertical direction V are shown on the face plate portion.

First, a plurality of vertically long linear cathodes 10 each having an oxide formed on the surface of a tungsten wire are independently arranged in the horizontal direction at equal intervals. The number of linear cathodes 10 and the intervals at which they are arranged are arbitrary, and for example, the display screen size is 1
Assuming 0 ", the horizontal spacing is about 10m
In m, 20 linear cathodes are arranged vertically with a length of about 160 mm. On the side opposite to the face plate portion 9 with the linear cathode 10 interposed therebetween, the linear cathode 10 is adjacent to the linear cathode 10 and is vertically divided at an equal pitch on the insulating support 11 and is electrically divided to be elongated in the horizontal direction. A vertical scanning electrode 12 is arranged. These vertical scanning electrodes 12 are formed as independent electrodes equivalent to the number of horizontal scanning lines (about 480 in the NTSC system) in the vertical direction when displaying a normal television image. Next, from the side of the linear cathode 10 between the linear cathode 10 and the face plate 9, a planar electrode having an opening at a portion corresponding to the linear cathode 10 is sequentially divided between adjacent cathodes, A second grid which has the same openings as the first grid electrode (hereinafter G1) 13 and G1 electrode 13 for applying a beam signal to each of the electrodes to perform beam modulation, and which is not electrically divided in the horizontal direction. An electrode (hereinafter G2) 14 and a third grid electrode (hereinafter G3) 15 are arranged. Next, a fourth grid electrode (hereinafter referred to as G4) 16 having the same opening as the G2 electrode 14 or the G3 electrode 15 or having a wide opening in the horizontal direction is arranged. Next, the horizontal focus electrode 17 and the horizontal deflection electrode 18, which are formed on the surface of the insulating support 19 by plating or vapor deposition, are arranged symmetrically with respect to each electron beam linear axis and horizontally at the same interval as the cathode interval. Then, a light emitting layer composed of the phosphor 7 and the metal pack electrode 8 is formed on the inner surface of the face plate 9. In color display, the phosphors are sequentially formed in the horizontal direction as red R, green G, and blue B stripes or dots.

Next, the operation of the color cathode ray tube will be described with reference to FIGS. A current is applied to the linear cathode 10 to heat it, and a voltage substantially equal to the potential of the cathode 10 is applied to the G1 electrode 13 and the vertical scanning electrode 12. At this time G1, G
A voltage (100 to 300 V) higher than the potential of the cathode 10 is applied to the G2 electrode 14 so that the beam advances from the cathode 10 toward the two electrodes (13, 14) and the beam passes through each electrode aperture. Here, in order to control the amount of the beam passing through the openings of the G1 and G2 electrodes, the voltage of the G1 electrode 13 is changed. The beam that has passed through the aperture of G2 electrode 14 is G3 electrode 15 → G4
The process proceeds from the electrode 16 to the horizontal focus electrode 17, and a predetermined voltage is applied to these electrodes so that the electron beam forms a small spot on the phosphor screen. Here, the vertical beam focus is performed by the electrostatic lens formed at the exit of the aperture of the G4 electrode 16, and the horizontal beam focus is performed by the electrostatic lens formed between the horizontal focus electrode 17 and the horizontal deflection electrode 18. Done with a lens. The beam that has passed through the horizontal focus electrode 17 is horizontally deflected by the horizontal deflection electrode 18 by a sawtooth wave or step wave deflection voltage with a horizontal scanning period with a predetermined width,
The phosphor 7 is stimulated to obtain a luminescent image. In order to obtain a color image, when each electron beam horizontally scans the phosphor 7 as described above, a modulation signal of a color corresponding to the color phosphor on which the electron beam is incident is applied to the G1 electrode 13.

Next, vertical scanning will be described with reference to FIG. As described above, the electric potential of the space surrounding the linear cathode 10 is controlled from the linear cathode 10 by controlling the voltage of the vertical scanning electrode 12 so that the electric potential is positive or negative than the electric potential of the linear cathode 10. The generation of electrons is controlled. At this time, if the distance between the linear cathode 10 and the vertical scanning electrode 12 is small, the voltage for controlling ON / OFF of the beam from the cathode may be small. When the interlace system is adopted for the vertical scanning electrodes 12, in the first field, a signal for generating a beam (hereinafter, ON) from the vertical scanning electrodes 12A for only one horizontal scanning period (hereinafter, 1H), During the next 1H, the signal that turns on the beam at 12C is applied, and subsequently, the signal that turns the beam on only every 1H is applied to every other vertical scanning electrode. When 12X at the bottom of the screen ends, the first 1 field Vertical scan of is completed. In the next second field, a signal for turning on the beam only during 1H is similarly applied from 12B, and one frame of vertical scanning is finally completed by scanning up to 12Y.

Next, regarding a signal processing system until a video signal is applied to a beam modulation electrode of a cathode ray tube having a plurality of beam generating sources in the horizontal direction like the flat plate cathode ray tube, a generally well-known method is described below. This will be described with reference to FIG.

Based on the television sync signal 42, a timing pulse generator 44 generates a timing pulse for driving a circuit block described later. First, the R, G, B three primary color signals (E _R , E _G , E _B ) 41 demodulated by one timing pulse among them are converted into a digital signal by the A / D converter 43, and a 1H signal is converted. Input to the first line memory circuit 45. When all the signals for 1H are input, the signals are simultaneously transferred to the second line memory circuit 46, and the next 1H signal is also input to the first line memory circuit 45. The signal transferred to the second line memory circuit 46 is stored and held for 1H and also sent to the D / A converter (or pulse width converter) 47.
Here, it is converted into the original analog signal (or pulse width modulation signal), amplified, and applied to the modulation electrode (G1) of the cathode ray tube. Such a line memory circuit is used for time-axis conversion, and its concrete description will be described with reference to the signal waveforms shown in FIG.

The number of beams used to scan the effective screen area (that is, the number of cathodes) is n, and the area where each beam is horizontally scanned is 2 triplets (1 triplet is one set of R, G, B phosphor stripes). Then, the video signal insertion time T of each R, G, B primary color signal 41 during a certain 1H is divided into T / n, and the time axis of the video signal of each period is multiplied by n to obtain T, which is on the fluorescent surface. If the arrangement of the fluorescent stripes is R → G → B, each primary color signal multiplied by n and extended to T time is T /
Is gated by the gate pulse 6 hours width, E _R → E _G → E
_It is converted into a time series signal 48 called _B and inputted to a predetermined G1 electrode.

In a flat-panel cathode ray tube that displays a full color screen by the above vertical scanning, beam modulation, and horizontal scanning, when trying to display a faithful color image, it is possible to detect a color phosphor into which an electron beam is incident. A corresponding color modulation signal should be applied to the G1 electrode, but this cathode ray tube has no function and the hue changes when the horizontal deflection width changes. If the deflection electrode intervals are not uniform, color images with different hues are produced in each horizontal block.

In the flat cathode ray tube that displays an image by the vertical scanning, the beam modulation, and the horizontal scanning as described above,
In order to display a faithful color image, a modulation signal of a color corresponding to the color phosphor on which the electron beam is incident must be applied to the G1 electrode. As the method, the applicant has previously proposed a method of knowing the timing of applying the modulation signal based on the index signal. The method will be described with reference to FIGS. 8 and 9.

As shown in FIG. 8A, an index area 51 is provided outside the image display area 52 on the face plate 50. As shown in FIG. 9, index phosphors 61 are applied to the index regions 51 so that the relative positions of the image display regions 52 and the color phosphors 60 have a predetermined relationship. The beam is scanned to emit light. The index phosphor 61 may have the same or different emission wavelength as the color phosphor 60. This light emission is converted into an electric signal by the photoelectric conversion element 53 placed on the front surface of the face plate, and the signal is subjected to processing such as waveform shaping and frequency division to obtain the index signal B (FIG. 8B). On the other hand, the light emission of the blue B phosphor in the image display area 52 is converted into an electric signal by another photoelectric conversion element 54 also placed on the front surface of the face plate,
Waveform shaping is performed to obtain the position signal B of the B color phosphor. The reason why the light emission of the B phosphor is received here is that a signal having a high response speed can be obtained because of the short afterglow.

If the assembling accuracy of the cathode ray tube is good, the phase relationship between the index signal a and the B position signal b thus obtained is
The relationship is as shown in FIG. 8B. Therefore, the time difference t ₁ , t ₂ , ... From each rising part of the index signal B to each rising part of the B position signal B is measured and stored in the memory 56. This operation is performed over the entire image display area in advance without applying the color modulation signal. Then, when actually displaying an image, the time when the time stored in the memory 56 elapses from each rising portion of the index signal B is set as the timing of applying the B color signal. For the R and G color signals, the application timing can be obtained by multiplying the timing signal by 3.

As described above, the color modulation signal corresponding to the color phosphor on which the electron beam is incident is applied to the G1 electrode, and a faithful color image display is performed.

Problems to be Solved by the Invention The phase relationship between the index signal B and the B position signal B described above cannot always be said to be obtained as shown in FIG. 8 depending on the assembly accuracy of the cathode ray tube. That is, as shown in FIG. 10, when the starting position of the horizontal scanning of the electron beam is relatively deviated between the image display area and the index area, the phase relationship between the index signal and the B position signal does not correspond correctly. As a result, the timing of applying the color modulation signal to the G1 electrode and the color phosphor on which the beam is incident do not correspond correctly.

For example, if the scanning start position of the electron beam is the point indicated by 1, the first pulse I ₀ of the index signal a
The pulse B ₀ of the B position signal B, which should correspond to, is delayed from the correct position by one period, that is, by one triplet of the color phosphor. Further, if the scanning start position of the electron beam is at the point indicated by 2, it means that the phase of the B position signal (b) is ahead of the phase of the index signal (b) and corresponds to the pulse B ₀ of the B position signal (b). There should be no pulse of the index signal a, and the timing of applying the modulation signal is lost. Therefore, the scanning start position of the electron beam must be at a point such that the phase of the B position signal B does not lead the phase of the index signal B and is delayed by one triplet or more. However, it is difficult to suppress the assembling accuracy of the cathode ray tube so that the above-described relationship is satisfied over the entire image display area.

Means for Solving Problems The index area is provided wider than at least one horizontal scanning section of the image display area by at least two triplets of the color phosphor, and the frequency of the obtained index signal is divided into halves. By providing means and further means for continuously changing the phase of the index signal, the phase relationship with the B position signal can be adjusted correctly.

By the means described above, the index signal can be obtained from a range wider than at least two triplets of the color phosphor from one horizontal scanning section of the image display area. Therefore, even if the phase of the B position signal leads the phase of the index signal. , There may be a corresponding pulse of the index signal, and the means for adjusting the phase of the index signal makes it possible to adjust the correspondence between the pulse of the index signal and the pulse of the B position signal to the correct position. Further, by the means for dividing the frequency of the index signal by half, the range in which the phase can be adjusted can be expanded to the two triplets of the color phosphor. Therefore, the phase shift between the index signal and the B position signal can be tolerated more than twice as much as the conventional one, so that the tolerance of the assembly accuracy of the cathode ray tube is 2 times.
It can be more than doubled.

Embodiment FIG. 1 is a block diagram showing the main part of a color image display device according to an embodiment of the present invention, and FIG. 2 is a diagram showing the waveform of each part. The light emitted from the index fluorescent body is converted into an electric signal by the photoelectric conversion element 53, and is shaped into a rectangular wave by the waveform shaping circuit 70 by a limiter or the like. As shown in FIG. 6 of the conventional example, the index fluorescent body 61 is applied at a pitch of 3/2 times the pitch of one triplet of the color fluorescent body 60, so that the frequency divider 71 is Divide by 3 to match the repetition frequency of the B position signal. The frequency divider 71 can be realized by a delay circuit, an E-OR circuit and a counter. The output of divider 71 is the counter
A pulse selection circuit 72 composed of an AND circuit selects an odd-numbered pulse and an even-numbered pulse. That is, the index signal is converted into two systems by dividing the conventional signal by 1/2. The index signals D and E are input to the phase difference measuring circuits 77 and 78 via the phase shift circuits 73 and 74, respectively. Each of the phase shift circuits 73 and 74 is composed of two monostable multivibrators, and the index signals D and E can change the phase within the range of each repetition period. Therefore, the adjustment range of the phase can be performed up to two triplets of the color phosphor 60, while the light emission of the B phosphor is converted into an electric signal by the photoelectric conversion element 54, in the same manner as the index signal. After being shaped into a rectangular wave by the waveform shaping circuit 75, it is sorted into odd-numbered pulses and even-numbered pulses and input to the phase difference measurement circuits 77 and 78, respectively.

The phase difference measuring circuits 77 and 78 measure the phase difference between the odd-numbered pulse and the even-numbered pulse of the index signal and the B position signal, respectively, and store them in the memory 56. Phase difference measurement starts counting the clock pulse synchronized with the horizontal drive signal (HD) with the index signal pulse,
The counting may be completed by the B position signal pulse.

As described above, the phase difference is measured after the index signal and the B position signal are each halved, and the phase of the index signal is made variable. Even if the phase causes a delay of one triplet or more of the color phosphor, the phase of both can be made to correspond to the correct position.

Further, the coating area of the index fluorescent body 61 is widened, and as shown in FIG.
Apply the index phosphor 61 over a wide range of two triplets or more. By doing so, the advance of the phase of the B position signal with respect to the phase of the index signal, which has occurred in the conventional example, can be allowed up to two triplets, and the index signal exists for the first pulse of the B position signal. The situation of not doing it disappears.

EFFECTS OF THE INVENTION According to the present invention, the shift of the phase of the index signal and the shift of the B position signal can be tolerated to a range more than twice the conventional range. Therefore, the assembly of the cathode ray tube which is the main factor of the shift The accuracy margin can be doubled or more.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a main part of a color image display device according to an embodiment of the present invention, FIG. 2 is a waveform diagram of each part of FIG. 1, and FIG.
FIG. 4 is a schematic diagram of a fluorescent surface of a color cathode ray tube of the present invention, FIG. 4 is a perspective view of a flat plate type color cathode ray tube which is a prior art by the present applicant, and FIGS. Vertical cross-sectional views, FIGS. 6A and 6B are vertical scanning explanatory diagrams, FIG. 7 is a signal processing system diagram of a color image display device, and FIG. 8A is an explanatory diagram of the basic principle of the index system. B is a waveform diagram in the same system, FIG. 9 is a diagram showing a fluorescent surface of a color cathode ray tube in a conventional example, and FIG. 10 is a diagram for explaining problems of the index system in the conventional example. 50: Flat plate color cathode ray tube, 51: Index area, 52: Effective screen area, 53, 54: Photoelectric conversion element, 56
...... Memory, 60 ...... Color phosphor, 61 ...... Index phosphor, 70,75 ...... Wave shaping circuit, 72,76 ...... Pulse selection circuit, 73,74 ...... Phase shift circuit, 77,78 ...... Phase difference measurement circuit.

Front Page Continuation (72) Inventor Kaoru Tomii 3-10-1 Higashisanda, Tama-ku, Kawasaki City, Kanagawa Prefecture Matsushita Giken Co., Ltd. (56) Reference JP 62-172893 (JP, A) JP 61 -202592 (JP, A)

Claims (1)

[Claims] 1. A plurality of electron beam generators, an electron beam modulator corresponding to each of the plurality of electron beams generated by the plurality of electron beam generators, and at least three primary color phosphors of red, green and blue. Is an image display area that is repeatedly and sequentially arranged in the horizontal direction through a black area, and outside the image display area, is composed of an index area in which index phosphors are arranged, and the horizontal width of the index area is the A light emitting unit which is set to be wider than the horizontal width of the image display region by at least two triplets of the three primary color phosphors and which emits light by the electron beam bombardment; the image display region and the index region; Simultaneous scanning is performed by different electron beams among a plurality of electron beams, and the light emission of the index region is detected by the photoelectric conversion element. A digital signal, and a unit that divides the repetition frequency of the index signal into 1/2, a unit that adjusts the phase of the divided index signal, and a video signal that is displayed in the image display area. A color image display device comprising means for controlling the time to be applied to the beam modulating means by means of the index signal outputted from the phase adjusting means.