JPS6124130A - flat plate cathode ray tube - Google Patents

Abstract

PURPOSE:To reduce the distance between three electron beams at the center of deflection, by making convergence electrodes at both ends longer than other convergence electrodes, and by applying a lower voltage to the convergence electrodes than that to deflection electrodes near the convergence electrodes so as to converge the three electron beams. CONSTITUTION:A spot making portion 21 generates three electron beams 22a, 22b and 22c of very small cross-sectional areas respectively. The beams 22a, 22b, 22c come out in parallel with each other from the spot making portion 21 and go in between convergence electrodes 24a, 24b through a shield electrode 23. The convergence electrodes 24a, 24b differ from each other in length. The electron beams 22a, 22c are bent toward the other electron beams 22b by the distortions of electric fields generated between horizontal deflection electrodes 25 and the convergence electrodes 24a, 24b. Though the electron beams 22a, 22c are once bent toward the other central beam 22b, the angle of the convergence of these three beams is decreased by divergent electric fields generated at the entrance of a deflecting portion by a voltage applied to the deflection electrodes 25 and higher than that applied to the convergence electrodes 24a, 24b.

Description

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

The structure of the conventional example and its problems As a flat cathode ray tube, for example, the special song Sho 54-60655
The publication describes a modular flat panel display device, in particular a display device in which three beams are concentrated in each channel. A conventional example is shown in FIG. Three electron beams 12 coming out through the beam guide plate 11 &
, 12b.

12C is focused by the focusing grid electrode 13, accelerated by the accelerating grid electrode 14, and then transferred to the protective electrode 16a.

16b, it enters the deflection region where the scanning electrode 16 is present. Here, three electron beams 12a.

The convergence of 12b and 12C is determined by the distance between the acceleration grid electrode 14 and the shadow mask 17, the beam interval, and the voltage applied to the protection electrode 15a, which depends on the voltage applied to the acceleration grid electrode 14 and the shadow mask.

That is, the convergence is between the protection electrode 15a and the scanning electrode 1.
However, it should be noted that this electric field strength also affects the spot diameter of the electron beam.

Furthermore, when considering the case of scanning with three electron beams, such as when displaying in color, the smaller the distance between the three electron beams at the center of deflection, the less distortion caused by deflection. In this case, when trying to reduce the distance between the three electron beams at the center of deflection, the acceleration grid electrode 13
However, if the distance to the shadow mask 17 is large, the device becomes thick and heavy, which is disadvantageous in terms of assembly accuracy. For this reason, in the conventional configuration shown in Fig. 1, changes in the spot diameter of the electron beam and changes in the arrival position due to the processing accuracy and assembly accuracy of the electrodes, and changes in the spot diameter of the electron beam due to deflection. As for such corrections, unless there is any means to do so, convergence errors and uneven spot diameters of the three electron beams are unavoidable.

This has a negative effect on image quality in terms of brightness, color purity, and the like.

Purpose of the Invention The purpose of the present invention is to solve the above-mentioned problems, and to correct deviations in the spot diameter and convergence of an electron beam caused by errors due to processing accuracy and assembly accuracy of electrodes and errors due to deflection, This provides a convergence electrode structure in which the distance between three electron beams at the center of deflection is small.

Structure of the Invention The present invention includes a portion for forming three spot-shaped electron beams, a deflection portion for deflecting the three electron beams, and a portion for forming three spot-shaped electron beams.
It is a flat cathode ray tube consisting of a convergence part that focuses the main beam to a single point, a shadow mask, and a face part in which three types of phosphors are formed in a predetermined pattern.The convergence electrode is in the center. The lengths are different between those corresponding to the beam and those corresponding to both side beams.

Description of examples The present invention will be described in detail below based on examples.

FIG. 2 is a horizontal sectional view of a flat cathode ray tube according to an embodiment of the present invention.

Electron beams 22a and 2 are emitted in parallel from the spot forming section 21 that forms three spot-shaped electron beams.
2b and 22c pass through the shield electrode 23 and enter the convergence electrodes 24&, 24b. Since the convergence tJ24& and 24b have different lengths, and the electrode 24b is longer than the electron fM2+a, due to the distortion of the electric field created between it and the horizontal deflection electrode 25, the electron beams 22L and 220 become the electron beam 22b. It can be bent towards the right direction. Electron beam 22 bent further toward the center
, 22Ct is a convergence electrode 24a.

The angle of convergence of the three electron beams becomes loose due to the divergent electric field at the entrance of the uneven thickness portion created by the voltage applied to the deflection electrode 25 which is higher than the voltage applied to the deflection electrode 24b.

FIG. 3 shows the convergence electrodes 24a and 2, which is used to explain in more detail how the three electron beams are focused.
4b shows the equipotential distribution between the deflection electrode 25 and the deflection electrode 25. The conditions for the three electron beams to be focused on one point are the length, spacing, and applied voltage of the convergence electrodes 24 and 24b, the length and applied voltage of the deflection electrode 25, the distance between the convergence electrode 24b and the deflection electrode 25, and Once the distance between the convergence tFM 24 & and the shadow mask 26 is determined, it can be uniquely determined.
The convergence electrodes 24&, 24b (7) are 5 mm in length, 6 and 26 nun, and the applied voltage is 1
．． In this example, the deflection electrode 25 has a length of 60 mm, the applied voltage is 10 KV, and the distance between the convergence t4M24& and the shadow mask 26 is 100 mm.

Three mutually parallel electron beams 22&, 22b enter the convergence electrodes 24&, 24b.

In view of the symmetry of the equipotential line at the exit of the convergence electrode 241L, the beam 22C does not bend when facing the center beam 22b, but travels straight while being focused.
The beams on both sides; 2a and 22c are bent toward the central beam 22b while being focused due to the asymmetry of the equipotential lines created between the convergence electrodes 24& and 24b. Furthermore, at the entrance of the deflection electrode 26, the equipotential lines act as a diverging effect, indicating that the once bent double-sided beam 222L.

220 will have its slope relaxed.

Return to Figure 2 Convergence! 412ta.

The three electron beams whose trajectories are corrected by the electric field at the exit of the deflection electrode 24b and the entrance of the deflection electrode 26 are focused on one point on the shadow mask 26, and on the phosphor screen 27, a predetermined phosphor is illuminated. It turns out.

By obtaining the equipotential distribution shown in Figure 3, the distance between the three electron beams at the center of deflection becomes smaller, which may cause irregularities in the spot diameters of the three electron beams due to deflection and errors in convergence. will also become smaller.

FIG. 4 shows each convergence electrode 240.2
4d, 24θ, 24f, 24g, and 24h, and can be typified by, for example, a structure made by vapor-depositing metal on an insulating substrate 241.

By adopting this structure, it is possible to more precisely correct the spot diameter of the electron beam and the misconvergence of the three electron beams due to errors caused by electrode processing precision and assembly precision, and aberrations caused by deflection. Because it becomes possible in detail,
You can get better image quality. The other electrode configurations and their functions are completely the same as those shown in FIG. 2, so their explanations will be omitted.

DETAILED DESCRIPTION OF THE INVENTION As described above, in the present invention, the convergence electrodes at both ends are made longer than the convergence electrode at the center, and a voltage lower than the voltage applied to the adjacent deflection electrodes is applied to the three convergence electrodes. It is characterized by the convergence of the electron beams, and because the distance between the three electron beams at the center of deflection can be reduced, it is less susceptible to mechanical precision and errors due to deflection, and By dividing the convergence electrodes and making them independent, it is possible to correct various errors.

[Brief explanation of the drawing]

Figure 1 is a partially enlarged sectional view of a conventional flat-plate cathode ray tube;
The figure is a partially enlarged sectional view of an embodiment of the flat plate cathode ray tube according to the present invention, FIG. 3 is a partially enlarged view of the configuration of FIG. 2, and FIG.
The figure is a partially enlarged sectional view of another embodiment of the flat plate cathode ray tube according to the present invention. 11... Beam guide plate, 12.22... Electron beam, 13... Focusing grid electrode, 14...
・River・Acceleration grid electrode, 15...Protection electrode,
16... Scan ti, 17126 River... Shadow mask, 21... Spot forming section, 23...
Curved shield electrode, 24... Convergence electrode, 25... Mountain deflection electrode, 27... Fluorescent screen,
28...Curved vacuum envelope. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Of course

Claims (2)

[Claims] (1) means for forming three spot-shaped electron beams in a vacuum envelope; a convergence electrode for converging the three electron beams to one point; and a deflection electrode for deflecting the three electron beams. , comprising a shadow mask and a face portion in which three types of phosphors are formed in a predetermined pattern, and the convergence electrode includes a first electrode disposed in the center and a first electrode disposed outside the convergence electrode. A flat cathode ray tube comprising a second electrode which is longer. (2) The convergence electrode is divided independently,
The flat cathode ray tube according to claim 1, wherein the three electron beams are individually corrected.