JPH043057B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a flat cathode ray tube.

As shown in FIGS. 1 and 2, the flat cathode ray tube includes, for example, a plate-shaped first glass substrate 1a.
and a second glass substrate 1b having a peripheral wall portion _1b1 and a flange portion _1b2 in a dish-like shape and having the flange portion _1b2 bonded and sealed to the peripheral portion of the substrate 1a. A network tube 1c is provided extending outward along the surface direction of the flat tube body 1, and an electron gun 2 is disposed within the network tube 1c.

A light-transmissive target electrode 3 is adhered to the inner surface of the substrate 1a, and a fluorescent surface 4 is coated thereon. Alternatively, although not shown, a conductive film is applied to the substrate 1a in the form of a frame, for example, and a fluorescent surface 4 is applied within the frame over the conductive film, and a metal back layer is formed on the fluorescent surface 4. and a frame-shaped conductive layer constitute a target electrode.

On the other substrate 1b side, target electrodes 3,
Therefore, the back electrode 5 is placed opposite the fluorescent surface 4. The network tube 1c and the electron gun 2 are arranged so as to extend along the surface direction of the flat tube, that is, the surface direction of the fluorescent surface 4, as described above. In the illustrated example, the main deflection system is formed such that the axis of the electron gun 2 is along the vertical scanning direction at the center of the fluorescent surface 4, and between the fluorescent surface 4, the target electrode 3, and the back electrode 5. This is the case when they are placed so as to face each other in the center of the space. Reference numeral 6 deflects the electron beam emitted from the electron gun 2 and directed toward the above-mentioned main deflection system in a direction substantially perpendicular to the axial direction of the electron gun 2 and substantially along the surface direction of the fluorescent surface 4 (hereinafter referred to as horizontal deflection). with a deflection means that causes
This means 6 includes, for example, an electromagnetic wire ring 6 attached to a magnetic core 6a.
b is constituted by electromagnetic deflection means arranged. Similarly, 7 is a deflection means for deflecting the electron beam emitted from the electron gun 2 and directed toward the main deflection system in a direction perpendicular to the fluorescent surface 4 (hereinafter referred to as vertical deflection). Electrostatic deflection plate 7
It is composed of a and 7b.

With such a configuration, the electron beam emitted from the electron gun 2 is horizontally scanned onto the fluorescent surface 4 by the horizontal deflection means 6, and is deflected by the main deflection system by the vertical deflection means 7. The electron beam is scanned vertically on the fluorescent surface 4 by the cooperation of the electron beams. Here, a high voltage _V0 , for example 5KV, is applied to the target electrode 3 forming the main deflection system.
The back electrode 5 has a relatively lower voltage, but is likewise applied with a high voltage _V1 , for example 4 KV.

Normally, a voltage V ₀ is applied to the vertical deflection means 7 using electrostatic deflection means, that is, the electrode plates 7a and 7b, and a vertical deflection signal is applied between the electrode plates 7a and 7b. The trajectories of the electron beam in the cross section in the direction perpendicular to the fluorescent surface 4 with such a configuration are indicated by symbols a ₁ , a ₂ , a ₃ in FIG.
As shown in FIG.
The angle η (hereinafter referred to as the angle of incidence) formed with As shown in FIG. 4, if the electron beam directed toward the fluorescent surface 4 is a cylindrical body indicated by the symbol b, the relationship between the angle of incidence η on the fluorescent surface 4 and the beam spot diameter on the fluorescent surface 4 is , as is clear from FIG. 4, as η becomes smaller, the length of the spot on the fluorescent surface 4 in the vertical direction increases, so the diameter of the spot on the fluorescent surface 4 in this vertical direction and the diameter of the electron beam b, that is, the magnification, M=
The relationship between sin1/η and the incident angle η is as shown by curve 8 in FIG. Therefore, if the incident angle η of the electron beam on the fluorescent surface 4 is, for example, 16° at the end of the fluorescent surface 4 near the electron gun 2 in the vertical scanning direction, then
Since the incident angle η at the farthest position is about 22°, the magnification M is on the incident side.
Although it is about 3.5, it becomes about 2.5 on the side opposite to the incident side, resulting in a significant difference in magnification in the vertical direction, which causes spot distortion on the fluorescent surface 4.

The present invention provides a flat cathode ray tube that eliminates these drawbacks.

That is, in the present invention, in the above-mentioned flat cathode ray tube, a specific potential relationship is applied to the beam emitted from the electron gun toward the main deflection system by using, for example, electrostatic deflection of the vertical deflection system. A lens system is formed that produces so-called astigmatism, which reduces the beam spot in the direction perpendicular to the phosphor surface and the back electrode, and the lens system gradually lands closer to the electron gun, especially with respect to the phosphor surface. In other words, a focusing lens system is formed that reduces the degree of reduction for beams that land farther from the electron gun.

An example of the arrangement of each electrode of the flat cathode ray tube according to the present invention is shown with reference to FIG. In the illustrated example,
The electron gun 2 includes, for example, a directly heated cathode K, a first grid electrode _G1 , a second grid electrode _G2 , and a third grid electrode.
A configuration is adopted in which a grid electrode _G3 and a fourth grid electrode _G4 are arranged in sequence. As described above, an electrostatic deflection electrode plate 7a is provided between the electron gun 2 and the main deflection system, that is, the opposing portion of the target electrode 4 and the back electrode 5.
and 7b are arranged, and in particular, the direct current voltage V ₁ applied to the back electrode 5 is applied to this means 7, that is, the electrode plates 7a and 7b.
That is, a voltage V1, which is lower but higher than the highest anode voltage _V0 applied to the target electrode 4, is applied as a DC voltage, and in addition to this, the vertical deflection signal voltage +α is _applied .
Although ~-α is superimposed, in this case, especially the back electrode 5
This signal voltage +α for the electrode 7a adjacent to
~−α is applied.

An end plate 8 is provided at the end of the final stage electrode of the electron gun 2, in this example the end of the fourth grid _G4 facing the vertical deflection means 7, in which an electron beam transmission hole 8a is provided. . This beam transmission hole 8
It is desirable to select the diameter φ of a to be approximately the same as the distance d between the pair of electrostatic deflection plates 7a and 7b of the vertical deflection means 7 on the beam incidence side, and also the distance l between the end plate 8 and the means 7. It is preferable that the distance d between the electrode plates 7a and 7b is approximately equal to the distance d between the electrode plates 7a and 7b on the beam incident side. A target voltage _V0 , for example, 5KV is applied to the final stage electrode of the electron gun 2, that is, the fourth grid _G4 . By the way, the first grid _G1 has 0 to -35V, the second grid
250V is applied to _G2 , and about 550V is applied to the third grid _G3 .

According to such a configuration, a high voltage of 5KV is applied to the final stage electrode _G4 of the electron gun 2, and a lower high voltage of 4KV is applied to the vertical deflection means 7 at the subsequent stage, so that A two-dimensional lens system having a focusing effect only in the vertical direction, as shown in FIGS. 7 and 8 by thin lines showing the equipotential surfaces between the two;
An astigmatic lens system is thus formed, so that the electron beam spot passing through this lens system is focused, ie reduced, with respect to the vertical deflection. When +α is superimposed on the electrode plate 7a, in other words, the electron beam is deflected toward the electrode plate 7a, and the beam is directed from the electron gun 2 side on the fluorescent surface 31 as shown by locus _a1 in FIG. When landing at a far position, the potential difference forming the above-mentioned two-dimensional lens system becomes shallow especially on the side of the electrode plate 7a given +α, and the lens effect is weakened. When -α is superimposed, that is, when the vertical scanning position is as shown by locus a 3 in FIG. ₃ , the two-dimensional lens effect is strengthened. As a result, the incident angle η as explained in FIG.
The reduction is weakened in the direction where It is possible to prevent the spot diameter from increasing in the vertical direction on the sides, and to obtain substantially circular spots on the phosphor surface 4 at each portion without distortion.

As described above, with the above configuration, it is possible to obtain the effect of dynamic correction regarding vertical deflection and spot distortion at the same time without providing any special dynamic correction signal.

Also, according to the above-described configuration, since the voltage _V1 lower than the anode voltage (target voltage) _V0 is applied to the vertical deflection means 7, here,
A decelerating electric field is applied to the electron beam, and since the electron beam is vertically deflected in this decelerating part, it is easily susceptible to that deflection, and the deflection voltage can be reduced accordingly. When the deflection means 6 also performs horizontal deflection, it becomes possible to reduce the power consumption for both horizontal and vertical deflection.

Further, the present invention is not limited to the above-described configuration, but can adopt various electrode arrangement configurations, examples of which are shown in FIGS. 9 to 11. Since the electron gun 2 in each of FIGS. 9 to 11 can have the same configuration as that explained in FIG. 5, only the side subsequent to the third grid _G3 is shown.
Although the arrangement of each electrode is shown as a schematic cross section, in each figure, the same reference numerals are given to the parts corresponding to those in FIG. 5, and redundant explanation will be omitted.

What is shown in FIG. 9 is a configuration in which an intermediate electrode 9 is arranged on the electron gun 2 side in parallel with the back electrode 5. In this case as well, the final stage electrode of the electron gun 2 and the In the example, the highest potential target voltage _V0 is applied to the fourth grid _G4 , and a high back electrode voltage V1 lower than the voltage _V0 is applied to both electrostatic deflection electrode plates 7a and 7b of the vertical deflection means ₇ . and an electrode plate 7a arranged on the back electrode 5 side.
The deflection signal voltage ±α is applied to both sides.
Then, a target voltage V ₀ is applied to the intermediate electrode 9. In such a configuration, a two-dimensional astigmatism lens system is constructed in the same way as described above, and the same effect as described above can be obtained, but in this case, the fourth grid G ₄ and the intermediate electrode A high voltage V ₀ is applied to the target electrode 9 and the target electrode 4, and a lower voltage V ₁ is applied to the means 7 between the two, thereby forming a unipotential type lens system.

Furthermore, in the example shown in FIG. 10, on the side where the target electrode 4 and hence the fluorescent surface are arranged,
Similarly, the target voltage V ₀ is applied opposite to the intermediate electrode 9.
A first auxiliary electrode 10 is provided, and a second auxiliary electrode 11 is further provided between this electrode 10 and the target electrode 4, and a back electrode potential V ₁ is applied to this. In this case, a unipotential lens system is constructed in the same way as the example shown in FIG. 9, but in this case, a bipotential single lens is also formed between the electrodes 10 and 11. .

Furthermore, in the example shown in FIG. 11, an auxiliary electrode 12 to which a back electrode voltage V ₁ is applied is provided between the target electrode 4 and the means 7 on the side where the target electrode 4 is arranged. The difference is that the back electrode potential _V1 is applied to the fourth grid _G4 , which is the final stage electrode of the electron gun 2, and the highest anode voltage, that is, the target voltage, is applied to both electrode plates 7a and 7b of the deflection means 7. This is because V ₀ was given. Also in this case, the vertical deflection signal voltages +α to -α are applied to the electrode plate 7a on the back electrode 5 side.

Even in such a configuration, an astigmatism lens system is constructed, but in this case, the means is located at a position of the electron beam path, particularly on the side where the target electrode 4 is arranged (lower side in the figure). 7-
Since a unipotential lens system consisting of the auxiliary electrode 12 and the target electrode 4 is constructed, the electron beam that passes toward the target electrode 4 side, that is, the position closer to the electron gun 2 on the fluorescent surface. A stronger lens effect acts on the electron beam that heads toward the fluorescent surface so as to land on the phosphor surface, and this beam can be more strongly reduced in the direction perpendicular to the target electrode 4. As a result, the distortion of the beam spot on the fluorescent surface can be corrected by so-called dynamic correction in accordance with its vertical scanning position.

As described above, according to the present invention, it is possible to effectively correct the distortion of the beam spot caused by the flat structure, and there is no distortion of the image, decrease in resolution, and color shift in color cathode ray tubes. It is capable of reproducing high-quality images.

[Brief explanation of drawings]

1 and 2 are a front view and a partially cutaway side view of a flat cathode ray tube, FIG. 3 is a diagram of its electrode arrangement, and FIG. 4 is an explanatory diagram of the relationship between the beam incidence angle and magnification. FIG. 5 is a curve diagram showing the relationship between beam incidence angle and magnification, FIG. 6 is a perspective view showing the arrangement of electrodes in an example of a flat cathode ray tube according to the present invention, and FIG.
8 and 8 are explanatory diagrams of the potential distribution, and FIGS. 9 to 11 are schematic cross-sectional views showing the arrangement of electrodes in other examples of the present invention, respectively. 1 is a tube body, 2 is an electron gun, 3 is a fluorescent surface, 4 is a target electrode, 5 is a back electrode, 6 is a horizontal deflection means,
7 is a vertical deflection means, 7a and 7b are electrostatic deflection electrode plates thereof, 9 is an intermediate electrode, and 10 to 12 are auxiliary electrodes.

Claims (1)

[Claims] 1. A back electrode is provided opposite to the phosphor screen, a main deflection system for electron beams is formed between the two, and an electron gun is arranged extending in the direction along the surface of the phosphor screen. In a flat cathode ray tube, an electrostatic vertical deflection electrode is provided between the electron gun and the main deflection system, and electrons entering the main deflection system from the electron gun are provided near the electrostatic deflection electrode. an electrostatic charge that reduces the beam in a direction substantially perpendicular to the phosphor screen and the back electrode, and the degree of the reduction is weakened with respect to the electron beam landing farther from the electron gun with respect to the phosphor screen; A flat cathode ray tube in which a lens system includes the electrostatic deflection electrode as a part of the constituent electrodes.