JPS62210794A - Color picture display device - Google Patents

Abstract

PURPOSE:To correctly correspond the phase of an index signal with that of a B position signal, by providing a memory which stores the index signal only for one horizontal scanning period, reading out the signal stored at the memory at every horizontal scanning period, and using it as the common index signal of a color modulation signal for whole of the effective pictures. CONSTITUTION:The emission of an index phosphor from an index area is converted to an electric signal, and is waveform-shaped and frequency divided, then it is stored on an index memory 62 by 1H of a certain horizontal scanning period. A stored index signal is read out at every horizontal scanning period, and is inputted to a phase difference measuring circuit 55. Also, the emission of a blue B phosphor is converted photoelectrically, and is amplified and waveform-shaped, then being inputted to the phase difference measuring circuit 55 as the B position signal. And the phase difference between them is measured, and is stored on a memory 56. And by setting the phase timing of the index signal at a position leading furthermore than that of the B position signal having the maximum lead of phase in the whole of the effective pictures, the phase difference between them is always measured and stored correctly.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for driving a flat cathode ray tube used in color television receivers, computer terminal displays, and the like.

2. Description of the Related Art There is a prior art flat cathode ray tube having a structure shown in FIG. In reality, each electrode is housed in a vacuum envelope (glass container), but the vacuum envelope is omitted in the figure to make the internal electrodes clear.

In addition, in order to clarify the horizontal and vertical directions of the screen that displays images, characters, etc., there is a horizontal direction H1 on the face plate.
A vertical direction V is illustrated.

Reference numeral 10 denotes a plurality of linear cathodes, which are long in the V direction and are formed by applying an oxide cathode material on the surface of a tungsten wire, and are arranged independently at regular intervals in the horizontal direction. Linear cathode 1o
On the opposite side of the face plate portion 28, vertical scanning electrodes 12 are arranged on the insulating support 11 in close proximity to the linear cathode 10, at equal pitches in the vertical direction, and electrically divided and elongated in the horizontal direction. Placed. These vertical scanning electrodes 1
2 is the number of horizontal scanning lines in the vertical direction if displaying a normal television image (approximately 48 in the case of NTSC system)
0% of the electrodes are formed as independent electrodes. Next, between the linear cathode 1o and the face plate portion 28, from the linear cathode 1o side, planar electrodes having openings in portions corresponding to the linear cathode 10 and the vertical scanning electrode 12 are placed adjacent to each other. A first grid electrode (hereinafter referred to as G1) 13 is divided between the linear cathodes 10 and performs beam modulation by applying a video signal to each electrode. A second grid electrode (hereinafter referred to as G2) 14 and a third grid electrode (hereinafter referred to as G3) 16 which are not divided are arranged. The G2 electrode 14 is for generating an electron beam from the linear cathode at 1°, and the G3 electrode 16 is for shielding the electric field from the subsequent electrode and the beam generating electric field. Next, a fourth grid electrode (hereinafter referred to as G4) 16 is arranged, and its opening is larger in the horizontal direction than in the vertical direction. FIG. 4 [A] shows a horizontal cross section of FIG. 3, and FIG. 4 [B] shows a vertical cross section.

Two electrodes 17 and 18 having openings that are sufficiently wider in the horizontal direction than in the vertical direction, similar to the openings in the G4 electrode 16, are placed downstream of the G4 electrode 16, as shown in Figure 4 CB). A vertical deflection electrode is formed by vertically shifting the center axes of the openings of the two electrodes. Vertical deflection electrode 17.18
At the rear stage, a plurality of vertically long electrodes are provided between the linear cathodes 1o toward the face plate portion 28@.

FIG. 3 shows an example of a three-stage case, in which each electrode is a first horizontal deflection electrode (hereinafter referred to as DH-1) 19, a second horizontal deflection electrode (hereinafter referred to as DH-2) 20, and a third horizontal deflection electrode (hereinafter referred to as DH-2). Hereinafter referred to as DH-3) 21, each of the horizontal deflection electrodes 19 to 21 is connected to a common bus line 22, 23, and 24 at every other horizontal direction. The DH-3 electrode 21 has a face plate portion 2.
The same voltage as the DC voltage applied to the metal back electrode 26 of No. 8 is applied, and a voltage for horizontal focusing of the beam is applied to the DH-1 electrode 19 and the DH-2 electrode 2°.

A light emitting layer consisting of a fluorescent surface 27 and a metal back electrode 26 is formed on the inner surface of the face plate portion 28 . On the phosphor surface, in the case of color display, phosphor stripes of red, R, green, G, and blue are sequentially formed in the horizontal direction via a black guard band.

Next, the operation of the color cathode ray tube will be explained. heating the linear cathode 10 by passing an electric current through it;
The same voltage as the potential of the cathode 1o is applied to the G1 electrode 13 and the vertical scanning electrode 12. At this time G1. G2 electrode (
13, 14) from the cathode 10, and the beam passes through each electrode aperture.
A voltage higher than the potential (for example, 1oo to 5ooV) is applied to the G2 electrode 14. Here the beam is 01. The amount of light passing through each hole of the G2 electrode is controlled by changing the voltage of the G1 electrode 13. The beam passing through the aperture of the G2 electrode 14 travels to the G3 electrode 16 → G4 electrode 16 → vertical deflection electrode 17, 18 → horizontal deflection electrode 19, 20, 21, but these electrodes have electrons on the fluorescent surface 26. A predetermined voltage is applied so that the beam forms a small spot. Here, the vertical beam focus is G3 electrode 16°G
The horizontal beam focus is D
This is performed using electrostatic lenses formed between each of H-1, DH-2, and DH-3.

The two electrostatic lenses are formed only in the vertical and horizontal directions, respectively, so that the vertical and horizontal spot sizes of the beam can be adjusted individually.

Also DH-1 (19), DH-2 (20), DH-3 (
A sawtooth wave, triangular wave, or staircase wave deflection voltage of the same voltage and synchronized with horizontal scanning is applied to the connected buses 22, 23, and 24 of 21), and the electron beam is deflected horizontally by a predetermined width. , light emission (at) is obtained by scanning the fluorescent surface 26 with an electron beam.

Next, vertical scanning will be explained using FIG. 5.

As described above, by controlling the voltage of the vertical scanning electrode 12 so that the potential of the space surrounding the linear cathode 1of is more positive or negative than the potential of the linear cathode 1o, The generation of electrons from 1o is controlled. At this time, the linear cathode 1o and the vertical scanning electrode 12
If the distance between the cathode and the cathode is small, the voltage for controlling generation (hereinafter referred to as ON) and interruption (OFF) of the beam from the cathode may be small. In the case of the current television system that uses an interlaced system, a predetermined deflection voltage is applied to the vertical deflection electrodes 18 and 19 for one field in the first field, and 12A of the vertical scanning electrode 12 is applied with a predetermined deflection voltage. The beam modulation electrode is applied only during one horizontal scanning period (hereinafter referred to as 1H), and the beam modulation electrode is applied to the other vertical scanning electrodes (12B to 12z). After 1H has elapsed, the beam ON voltage for 1H is applied only to 12B of the vertical scanning electrode, and then the beam ON voltage is applied to 12B of the vertical scanning electrode sequentially.
A voltage is applied to turn on the beam only during H, and when 122 at the bottom of the screen is completed, the first vertical scan of one field is completed. The next second feed is the vertical deflection electrode 17°1
The polarity of the deflection voltage applied to 8 is reversed, and this is applied for one field. The signal voltage applied to the vertical scanning electrode 12 is applied in the same manner as in the first field. At this time, the first
The amplitude of the deflection voltage applied to the vertical deflection electrodes 17 and 18 is adjusted so that the horizontal scanning line of the second field is between the horizontal scanning line positions of the beam caused by the vertical scanning of the field. As described above, the vertical scanning electrode 12 has the first. Second
The same vertical scanning electrode No. 1 voltage is applied to both fields,
By changing the deflection voltages applied to the vertical deflection electrodes 17 and 18 between the first field and the second field, one frame of vertical scanning is completed.

Next, we will explain a generally well-known method for the signal processing system until the video signal is applied to the beam modulation electrode of a cathode ray tube that has a plurality of beam generation sources in the horizontal direction, such as the above-mentioned flat-type cathode ray tube. This will be explained using Figure 6.

Timing pulse generator 4 based on TV synchronization signal 42
4, a timing pulse is generated to drive a circuit block to be described later. First, the three primary color signals of R, G, and B (EHtEqy
EB) 41 is converted into a digital signal by the A/D inverter 43, and the 1H signal is sent to the first line memory circuit 46.
Enter. 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 46. The signal transferred to the second line memory circuit 46 is stored and held for 1H, and is sent to the D/A converter (or pulse width converter) 47', where it is converted back to the original analog signal (or pulse width converter). It is converted into a modulation signal), which is amplified and sent to the modulation electrode (G1) of the cathode ray tube.
to be applied. Such a line memory circuit is used for time base conversion.

When trying to display a faithful color image on a flat cathode ray tube that displays images using the horizontal scanning, vertical scanning, and beam modulation methods described above, it is necessary to A modulation signal must be applied to the beam modulation electrode. As a method,
The applicant previously proposed a method for determining the timing to apply a color modulation signal based on an index signal. As shown in FIG. 7, the method for obtaining the index signal is to provide an index area 61 coated with an index phosphor on the face plate of the effective screen area coin, and convert the light emitted from the index area 61 into an electrical signal by a photoelectric conversion element 63. There is a way to do it. As shown in FIG. 8, the index phosphor 74 is coated so that the relative position with respect to the color phosphor 73 in the effective screen area is in a predetermined relationship, and the index phosphor 74 is applied so that the beam horizontal scanning similar to that in the effective screen area is applied. It emits light by doing this. This light emission is converted into an electrical signal by a photoelectric conversion element 63 placed in front of the face plate shown in FIG. 7, and subjected to processing such as waveform shaping and branching to become an index signal.

On the other hand, the light emitted from the blue (B) phosphor in the effective screen area is transferred to another photoelectric conversion element 64 similarly placed in front of the face plate.
The signal is converted into an electrical signal by , and the waveform is shaped into a position signal for the B color phosphor. The reason why the light emitted from the B phosphor was received here is that a signal with a fast response speed can be obtained by emitting light with a short afterglow.

The phase relationship between the index signal A and the B position signal port obtained in this way is as follows, if the assembly accuracy of the cathode ray tube is good.
The relationship is as shown in the waveform diagram of FIG. Therefore, the time differences 11, 12, . ... is measured and stored in the memory 66. This operation is performed in advance over the entire effective screen area without applying a color modulation signal. And when actually displaying the image,
From each rising edge of index signal A, memory 6
The time point at which the time stored in step 6 has elapsed is set as the timing for applying the B color signal. Furthermore, for the R9G color signal, the application timing can be obtained by multiplying this timing signal by three.

As described above, a 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 is displayed.

Problems to be Solved by the Invention However, the phase relationship between the index signal A and the B position signal port cannot necessarily be said to be the relationship shown in the lower part of FIG. 7, depending on the assembly accuracy of the cathode ray tube. For example, as shown in FIG. 8, if the horizontal scanning start position of the electron beam matches the point indicated by 1 in both the effective screen area and the index area, the first pulse IO of the index signal A will contain B. The first pulse B0 of the position signal corresponds correctly. However, when the horizontal scanning start position is relatively shifted between the effective screen area and the index area, as shown by point 2, the pulse I0 of the index signal
Pulse B0 of the position signal port does not correspond, but pulse B1 corresponds and is stored in memory. Therefore, the timing of the color modulation signal applied to the modulation electrode when the beam irradiates the position Bo is the timing that should correspond to the position B1, and if the linearity of horizontal deflection is poor, color shift may occur. become.

Means for Solving the Problems The present invention solves the above-mentioned problems by providing a memory that stores index signals for only one horizontal scanning period, and storing the signals stored in the memory for each horizontal scanning period. This is a common index signal that is read out during the period to obtain the application timing of the color modulation signal for the entire effective screen.

By taking the above-mentioned means, even if the horizontal scanning start position of the beam deviates between the effective screen area and the index area and the index signal and the B position signal cannot match in phase, the stored index signal can be maintained. Reading evening,
Since the timing can be changed, the phase of the index signal can be made to correspond correctly to the phase of the B position signal. Therefore, the phase difference between the index signal and the B position signal is always correctly measured and stored, and the position at which the beam irradiates the phosphor can be accurately matched with the timing at which the color modulation signal is applied.

Embodiment An embodiment of the present invention will be described with reference to FIGS. 1 and 2.

The index phosphor emission from the index region is
The signal is converted into an electric signal by the photoelectric conversion element 63, amplified by the amplifier circuit 6o, and then shaped into a rectangular wave by the waveform shaping/branching circuit 61 and converted into a frequency divided by 2/3. The thus converted signal is stored in the index memory 62 for one horizontal scanning period 1H. the stored index signal is read out every horizontal scanning period;
The signal is input to the phase difference measurement circuit 66. On the other hand, the light emitted from the blue B phosphor is also photoelectrically converted, amplified and waveform-shaped, and
The signal is input to the phase difference measurement circuit 66 as a position signal. Then, as described in the conventional example, the phase difference between the two is measured and stored in the memory 66.

By the way, index fist memory 6 of index signal
Writing and reading to and from 2 are controlled by writing and reading.
This is a readout W/R) control circuit 63. The control circuit is shown in detail in FIG. 2. At the time of writing, H is applied only during a certain 1H period based on the horizontal drive pulse (H2D).
A write gate pulse generation circuit 7o generates a gate pulse that becomes high or low. The gate pulse closes the teswitch 73 and leads the index signal to the index memory 62. Then, according to the address generated by the clock generator 64 and the address counter 72, the index signal is stored as a digital value for 1H period.

Of course, the index memory 62 may be an analog memory. Further, the clock generator 64 may use a PLL or the like to multiply the H and D frequencies.

Next, the time of reading will be explained. At this time, the read timing of the index signal is determined based on the HD pulse as in the case of writing. The read phase adjustment circuit 71 is a circuit that adjusts this timing, and can be configured with, for example, two monostable multivibrators. That is, the first monostable multivibrator determines the delay time from the HD pulse, and the output pulse drives the second monostable multivibrator.
Generate index signal read gate pulse.

Only during this gate pulse period, the address counter 7
2 supplies an address to the index memory 62 and reads out the index signal. Therefore, if the output pulse width of the first monostable multivibrator mentioned above can be changed using a variable resistor, the index signal read from the index memory 62 can be
This means that the phase timing can be freely set within 1H using the HD pulse as a reference.

If the phase timing of the index signal is set to a position further advanced than the B position signal, which has the most advanced phase in the entire effective screen area, the phase difference between the two will always be correctly measured and stored. 0 Effects of the Invention As described above, by providing a means for storing and holding an index signal and reading out the index signal at a free phase timing within each horizontal scanning period,
It becomes possible to always correctly match the phases of the index signal and the B position signal during phase difference measurement. As a result, it is possible to eliminate the influence of the assembly accuracy of the flat cathode ray tube, which is the main cause of variations in the phase correspondence between the two, and it also reduces the severity of assembly accuracy, leading to cost reductions. .

[Brief explanation of drawings]

Fig. 1 is a block diagram of the index processing section of a color image display device according to an embodiment of the present invention, Fig. 2 is a block diagram for explaining the details of Fig. 1, and Fig. 3 explains the basic principle of the system. FIG. 8 is a diagram showing the configuration of the fluorescent surface of the flat cathode ray tube and a waveform diagram for explaining the phase correspondence between the index signal and the B position signal. 60... Flat cathode ray tube, 61... Index area, 52... Effective screen area, 53
．． 6416. -...Photoelectric conversion element, 66... Memory, 62... Index memory, 63...
...W/R control circuit, 7°...Write gate pulse generation circuit, 71...Read phase adjustment circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 4
Figure B 5 Figure /2Q /2Y /2Z 4/ -1-3XF! , fg number base -- TV synchronization number 4 43 --- /I10 Conberg each --- Glimming par 7res originator, damp 2, each Glvr
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Claims (3)

[Claims] (1) An image display area provided with a fluorescent surface in which at least three primary color phosphors of red, green, and blue are arranged in sequence in a horizontal direction with a black area interposed therebetween, and an index phosphor outside the image display area. It has an image display element provided with an index area in which light bodies are arranged, the index area is scanned in synchronization with an electron beam that constantly scans the image display area, and the light emitted from the index area is converted into a photoelectric conversion element. A color image display device characterized in that an index signal obtained by receiving light is stored and held, and the index signal is read out every horizontal scanning period and used as a reference for applying a color modulation signal. (2) A color image display according to claim 1, characterized in that the index signal is stored and retained for one horizontal scanning period, and is used as a common index signal for all image display areas. Device. (3) The color image display device according to claim 1, wherein the color image display device has a phase variable function when reading out the index signal in each horizontal scanning period.