JPS6089043A - Flat cathode ray tube - Google Patents

Abstract

PURPOSE:To obtain beams having good focusing capability by arranging a modulation electrode which is divided into several sections and several slits, a plurality of switching electrodes each of which has the same constitution as the modulation electrode, and a plurality of focus electrodes. CONSTITUTION:A modulation unit of flat type cathode ray tube is formed in such a manner that a modulation electrode 44 which is divided into multiple groups each of which has three slits, switching electrodes 43 and 44 each of which has the same constitution as the modulation electrode but its slit locations are shifted by 1/3 pitch, and shielded electrodes 41 and 45 which are placed on both sides of these electrodes and whose slits are faced to those of these electrodes are arranged, and focus electrodes 46 and 47 which also serve as landing correction electrodes are placed between the shielded electrode and a fluorescent screen 48. Deflection of passing beam influenced by cut-off voltage which generates when divided width of the modulation electrode or switching electrode is smaller than the distance between electrodes is reduced and halation on the fluorescent screen is removed.

Description

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

Structure of conventional example and its problems 27.-2+ Figure 81 shows a conventional flat cathode ray tube. Electron beams emitted from a large number of linear cathodes 11 arranged in parallel in the vertical direction are made incident on an electron multiplier 12 in order to be multiplied. The electron beam coming out of the electron multiplier 12 is in the form of a sheet in the horizontal direction, which is passed through the modulation electrode 1.
The electron beam is modulated by a video signal in step 4 to control the amount of electron beam passing through this modulation electrode, and the controlled electron beam is accelerated by a high voltage applied to the fluorescent surface 16 and causes the fluorescent material to emit light. Electrodes 13.15 are inserted to focus the electron beam. Further, the modulation electrode 14 is finely divided in the horizontal direction, and a different video signal is applied to each modulation electrode to display the horizontal video on the screen, and to control the cathode potential in the vertical direction. The image will be scanned and one image will be displayed on the screen.

In order to obtain a color image with good resolution in such a configuration, one modulation electrode must not only have a narrow pitch but also be individually electrically insulated in correspondence with the narrow width of the phosphor. When modulation is performed using such narrow 3-way pitch modulation electrodes, the on-state beam adjacent to the off-state beam will be affected by the electric field of the off-state and will be deflected instead of going straight. . This beam deflection has the drawback of reducing the color purity and focus of the image, causing sharp unevenness in brightness, and greatly deteriorating the image quality. Figure 2 is a diagram showing the modulation electrode configuration of another conventional example. There are shield electrodes 21.23 on both sides of the modulation electrodes 22a, 22b, and a focus electrode 24 is arranged to improve the focus of the modulated beam. The slit width E of each electrode is 100 μm, and the plate thickness is 100 μm. Division width 71 of modulation electrode 22
! 2 is 40 μm, and the distance from the shield electrode 21.23 is 0.1 μm. The distance between the shield electrode 23 and the focus electrode 24 is 0.5111 m + focus electrode 2
4 and the fluorescent surface 25 is 6 distances. 20 is a cathode.

FIG. 3 is a diagram showing beam trajectories in the conventional electrode configuration shown in FIG.
to voltage is 50V, eov, -20V, 3
0V, 200V, 1 oxV'f;hruo As shown in Figure 3, the deviation of the beam arrival position on one 9th surface 26 reaches as much as 100 μm, and the beam does not reach the phosphor that should emit light. There will be no. The example in FIG. 3 also shows that even though the potential of each electrode is adjusted so that the beam width on the fluorescent surface 25 is minimized, the electrode configuration does not constitute a focusing system. There is.

As explained above, with the conventional modulation electrode configuration, it is impossible to obtain satisfactory characteristics in terms of the landing and focusing of an electron beam, and therefore, deterioration in image quality is unavoidable.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned problems, and aims to obtain a well-focused beam that is not deflected by modulation signals or switching signals.

Structure of the Invention The present invention is divided into a plurality of parts, each of which has a plurality of sulins 5/...
- A modulation electrode with a cut or aperture formed therein, a plurality of switching electrodes having a similar configuration, and a focus/landing correction electrode group having a slit or aperture opposite to the slit or aperture of each of the above electrodes. This is a flat cathode ray tube with an electrode configuration consisting of.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 4 is a diagram showing the structure of electrodes in the modulation section of a flat cathode ray tube according to an embodiment of the present invention.

The modulation electrode 42 is divided into a plurality of pieces, for example, three slits or openings, and the switching electrodes 43, 44
In this case, electrodes similar to the modulating electrode 42 are arranged shifted by three pitches. On both sides of the modulation electrode 42 and the switching electrodes 43, 44, the modulation electrode 42 and the switching electrodes 43, 44 are arranged.
Shield electrodes 41 and 45 having slits or openings are arranged opposite to the slits or openings of the shield electrode 4.
Between the phosphor 6 and the fluorescent surface 48, focus and defocus correction electrodes 46 and 47 are placed at an appropriate distance. The shield electrode 41.45 and the focus/understanding correction electrode 46.47 are of the same type, and are composed of a single electrode provided with slits or openings at regular intervals.

In the embodiment shown in FIG. 4, among the electron beams 40a, 40b, 40c that have entered the shield electrode 41, only the electron beam 40b is modulated in order to cause the R phosphor on the phosphor surface 48 to emit light. A video signal voltage of R is applied to the portion of one electrode element 42a of the electrode 42, and a voltage sufficient for the beam to pass is applied to the portion of the electrode element 4''a+44a of the switching electrodes 43 and 44. ,
Electrode element 43b.

A cutoff voltage sufficient to cut off the beam is applied to the portion 44b. Here, the greater the energy of the electrons entering the modulation electrode, the higher the cutoff voltage is required, and the higher the cutoff voltage, the greater the negative effect on the adjacent electron beam, creating a vicious cycle. In order to prevent this, on page 7 we will set a condition that the energy of the electrons entering the modulation electrode should be less than a few tens of eV on average.

The electron beam 40b is connected to the switching electrode 43b.

Although it is deflected under the influence of the shield electrode 46
By creating a crossover between the electron beam and the focus/landing correction electrode 46 and converging the expanding electron beam with the focus/landing correction electrode 46, the beam width of the fluorescent surface 48 is improved. Ru.

In this case, the crossover point is suddenly set to the fluorescent surface 48.
By avoiding exposure to strong electric fields caused by high voltages, it became possible to reduce the amount of beam deflection.

The plate thickness of each electrode is all 100 μm, and the shield electrode 4
The distance between the electrodes at 51 is 100 μm, the distance between the shield electrode 46 and the focus/landing correction electrode 47 is 200 μm, the distance between the focus/landing correction electrode 47 and the fluorescent surface 48 is 6 μm, and the distance between the focus and landing correction electrode 47 is 6 μm. 42
The dividing width of the switching electrodes 43 and 44 is 40 μm.

Next, the operating voltage conditions will be explained. Modulation voltage is 0■
, the shield electrode 45 is 60V, the anode voltage of the fluorescent surface is 10KV, and the focus/landing correction electrode 46 is 2V.
When the voltage is 80V, the focus and landing correction electrode 47
In the range of 250V to 3oOv, the beam width on the phosphor surface 48 falls within the pitch of the phosphor, but in the case of 280V or more, the electrons around the beam spread out after forming a crossover point. collides with the focus/lanting correction electrode 47 and deviates from the focus beam and reaches the fluorescent surface, resulting in poor beam focusing. On the other hand, when the voltage is lower than 280 V, even if electrons collide with the focus/landing correction electrode 47 and are reflected, they do not reach the fluorescent surface 48 but reach the focus/landing electrode 46. Therefore, it is preferable to operate the focus/landing electrode 47 with a voltage lower than the -focus/landing correction electrode 46 voltage.

Even when the modulation voltage is not OV, it is better to set the voltage of the focus 9 page/landing correction electrode 47 lower than the voltage of the focus/landing correction electrode 46. That is, of the two focus/landing correction electrodes, the potential of the electrode disposed on the fluorescent surface side is set to be lower than the potential of the other electrode. The table below shows an example of preferred operation.

Although the case where there is one modulation electrode and two switching electrodes has been described above, exactly the same effect can be expected for other electrode configuration examples as long as the modulation method is the same in principle.

Effects of the Invention As described above, the present invention provides a modulation electrode that is divided into a plurality of parts and each of which has a plurality of slits or openings.

A flat plate with an electrode configuration consisting of a plurality of switching electrodes having a similar configuration, and a group of 10 positive electrodes for focus/landing compensation having slits or openings opposite to the slits or openings of each of the above electrodes. In a type cathode ray tube, the deflection of the passing beam due to the effect of the cutoff voltage that occurs when the division width of the modulation electrode or switching electrode is smaller than the distance between the electrodes can be suppressed to a minimum, and the beam focus can also be made sufficiently small. Furthermore, by selecting the operating voltage, it is possible to eliminate beam halation on the fluorescent surface.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the electrode configuration of a conventional flat plate cathode ray tube, FIG. FIG. 4 is a cross-sectional plan view showing the electrode configuration of a flat cathode ray tube according to the undeveloped technology. 11... Linear cathode, 13.15...
・Focus electrode, 14...Modulation electrode, 16・
...Fluorescent surface. 41.45... Shield electrode, 42...
- Modulation electrodes - 43, 44... Switching electrodes, 46.47... Focus and landing correction electrodes, 48... Page 11 fluorescent surface. Name of agent: Patent attorney Toshio Nakao
1 @ Hinoki] ■Bottom “Ko = −−−−

Claims (2)

[Claims] (1) A modulation electrode divided into a plurality of parts each having a plurality of slits or apertures, a plurality of switching electrodes having a similar configuration, and a slit or aperture opposite to the slit or aperture of each of the electrodes. A flat cathode ray tube comprising a plurality of focus electrodes having apertures. (2) The focus electrode consists of two electrodes arranged between the modulation electrode section and the fluorescent surface, and the potential of the electrode arranged on the fluorescent surface side is lower than the potential of the other electrode. The flat cathode ray tube described in Section 1.