JPH03283240A - Flat type cathode-ray tube - Google Patents

Abstract

PURPOSE:To prevent the increase of an electron beam diameter due to the space charge effect and control the electron beam spot on a fluorescent screen uniformly and finely by concurrently scanning half regions near respective electron beam emitting means with two groups of electron beams in opposite directions to each other. CONSTITUTION:Multiple electron sources constituted of cathodes and heaters are arranged at positions opposite to slit-shaped openings of screen electrodes 51, 52 on electron source supporters 81, 84. Independently modulated electron beams 11, 12 are extracted from the electron sources by electron beam forming electrodes 82, 83 and 85, 86. The electron beams 11, 12 proceed in parallel with a fluorescent screen 2 and are deflected toward the fluorescent screen 2 respectively by vertically deflecting plates 41, 42 applied with the preset voltage. When the vertically deflecting plates 41, 42 applied with the preset voltage are switched in sequence, vertical scanning is performed. The deflected electron beams 11, 12 are finely deflected in the horizontal direction by two horizontally deflecting plates 6 faced to each other after passing the slit-shaped openings of the shield electrodes 51, 52 respectively and reach the fluorescent screen 2.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a flat cathode ray tube used as a color image display device for color television receivers, computer terminal displays, and the like. [Prior Art] Conventional flat cathode ray tubes include the first conventional example described in Japanese Patent Application Laid-Open No. 59-94339, and the first conventional example described in Japanese Patent Application Laid-open No. 1987-1934.
There is a second conventional example described in Publication No. 41. Those conventional examples will be explained using FIGS. 4 and 6. FIG. 4 is a sectional view showing the schematic structure of the first conventional example. Two electron guns 91 and 92 are arranged on the same axis, and each has three electron beams 91r, 91g, 91b, and 92.
r, 92g, and 92b are emitted parallel to the fluorescent surface 93. These electron beams are bent by a deflection area 95 formed by a deflection yoke 94 and cause the fluorescent surface 93 to emit light through a shadow mask 96. At this time, the deflection area 9
In 5, horizontal and vertical deflections are performed simultaneously. However, two groups of electron beams 91r, 91g, 91b, and 9
2r, 92g, and 92b are not deflected at the same time, and do not cause the fluorescent surface 93 to emit light at the same time. That is, after the electron gun 91 scans the right half from the center line 93c of the fluorescent surface, the video signal is switched to the electron gun 92, and the left half scan continues from the center line 93c of the fluorescent surface. FIG. 6 is a perspective view showing a schematic configuration of a second conventional example. This conventional example includes a flat vacuum container having a face portion 1 and a back panel portion 3, and a plurality of electrodes. The inner surface of the face portion 1 is as follows. The phosphor surface 2 has phosphors of three primary colors (red, green, and blue) applied in stripes in the vertical direction. Electrode means 97, 98, 99 for emitting a plurality of electron beams 10 arranged horizontally at predetermined intervals are provided at the lower end of the container. These electron beams 10 are deflected by a plurality of vertical deflection plates 4 arranged on the inner surface of the back panel portion 3 and pass through the shield electrode 5 . Thereafter, each electron beam 10 is slightly deflected in the horizontal direction by two opposing horizontal deflection plates 6, and reaches the fluorescent surface 2. In this way, in the second conventional example, the horizontal deflection and vertical deflection regions are separated,
Vertical scanning is performed by the plurality of vertical deflection plates 4, and horizontal scanning is performed by the plurality of horizontal deflection plates 6.

Problem 1 to be Solved by the Invention In order to display large-screen, high-definition images in the conventional example described above, the following problems must be overcome. In the first conventional example, problems include distortion of the electron beam spot due to the electron beam being obliquely incident on the fluorescent surface, and spot distortion and raster distortion due to deflection. especially,
Since the deflection angle when scanning an area close to the electron gun and an area away from the electron gun is significantly different, it is extremely difficult to appropriately correct spot distortion while adjusting the deflection angle. On the other hand, in the second conventional example, since scanning is performed using a plurality of electron beams, the deflection angle is uniform, and the above-mentioned problem can be avoided. However, as the screen becomes larger, the trajectory of the electron beam becomes longer, which causes problems such as an increase in the diameter of the electron beam due to space charge effects and misalignment of multiple electron beams. An object of the present invention is to prevent such an increase in the electron beam diameter and to uniformly and minutely control the electron beam spot on the fluorescent surface. [Means for Solving the Problems] In order to achieve the above object, in the present invention, a flat cathode ray tube is constructed using the following means. Inside the flat plate vacuum container, there is provided a fluorescent surface, a means for emitting a plurality of electron beams approximately parallel to the fluorescent surface, and a means for deflecting the electron beams toward the fluorescent surface. Deflection means is provided for scanning in the firing direction. Especially the means of emitting electron beams. They are arranged at both ends of this deflection means and configured to emit a plurality of electron beams in opposite directions. [Operation 1] The electron beam emitting means emits a plurality of electron beams in opposite directions parallel to the fluorescent surface. The electron beam deflecting means deflects each of these two groups of electron beams toward the fluorescent surface, focuses each on the fluorescent surface optimally, and performs scanning in the emission direction of the electron beam. As a result, the two groups of electron beams simultaneously scan a half region of the fluorescent surface near each electron beam emitting means. As a result of the above effects, the trajectory of the electron beam becomes shorter,
An increase in the electron beam diameter due to space charge effects or the like is prevented. Embodiments Hereinafter, embodiments of the present invention will be described using FIGS. 1 to 3 and FIG. 5. FIG. 1 is a partially cutaway perspective view showing the schematic structure of a flat cathode ray tube according to an embodiment of the present invention. The face portion 1 of the flat plate vacuum container is made of a transparent material such as glass. Inside, there are 3 red, green and blue
A fluorescent surface 2 is formed by applying primary color phosphors in stripes in the vertical direction. On the inner surface of the hack panel section 3 of the vacuum container, a plurality of vertical deflection plates 41, 42 are arranged parallel to the fluorescent surface 2 at predetermined intervals in the vertical direction. Shielding electrodes 51 and 52 each having a slit-like opening are provided opposite to these vertical deflection plates 41 and 42, and are supported in parallel to the fluorescent surface 2 by an insulating support 53. A plurality of horizontal deflection plates 6 are arranged at predetermined intervals in the horizontal direction between the shielding electrodes 51, 52 and the fluorescent surface 2, and are fixed by the same insulating support 53. An electron source support 81 and electron beam shaping electrodes 82 and 83 are arranged at the upper end of the area sandwiched between the vertical deflection plate 41 and the shielding electrode 51, and emit the electron beam 11 vertically downward. Similarly, at the lower end of the area sandwiched between the vertical deflection plate 42 and the shielding electrode 52,
An electron source support 84 and electron beam shaping electrodes 85 and 86 are arranged to emit the electron beam 12 vertically upward. An insulating support 53 extends between these electron beam emitting means, and electron beam position detection electrodes 7 are arranged on both sides of the insulating support 53, respectively. Furthermore, collimator electrodes 87 for controlling the emission direction of the electron beam are provided in proximity to the electron beam shaping electrodes 83 and 86, respectively. In this embodiment, the screen is scanned as follows. Although not clearly shown in Figure 1, the electron source support 81.84
In this case, a plurality of electron sources including cathodes, heaters, etc. are arranged at positions corresponding to the slit-like openings of the shield electrodes 51 and 52, respectively. From the electron sources, independently modulated electron beams 11.12 are extracted by electron beam shaping electrodes 82.83 and 85.86. These electron beams 11, 12 travel parallel to the fluorescent surface 2, and are deflected toward the fluorescent surface 2 by vertical deflection plates 41, 42 to which a predetermined voltage is applied. Vertical scanning is performed by sequentially switching the vertical deflection plates 41 and 42 to which this predetermined voltage is applied. Deflected electron beam 11
．． After passing through the slit-like openings of the shielding electrodes 51 and 52, each of the light beams 12 is slightly deflected in the horizontal direction by two horizontal deflection plates 6 facing each other, and reaches the fluorescent surface 2. At this time, horizontal scanning lines formed by the plurality of electron beams 11 and horizontal scanning lines formed by the plurality of electron beams 12 are simultaneously displayed on the fluorescent surface. FIG. 2 shows the vertical deflection plate 41.4 in the embodiment of FIG.
This figure shows how vertical scanning is performed by switching the voltage applied to 2. FIG. 2(a) is a sectional view of the flat cathode ray tube shown in FIG. 1 taken along a plane parallel to the horizontal deflection plate 6. FIG. The electron beam 1 covers the upper half of the fluorescent surface 2, bordering on the center line 2c.
1, and the lower half region is scanned by the electron beam 12. Vertical deflection plates 41a, 41b,...
Voltages are repeatedly applied to 41z, 42a, . . . , 42z to sequentially scan the two scanning areas on the fluorescent surface. In the figure, the trajectory of the electron beam at the start of vertical scanning is shown by a solid line, and the trajectory of the electron beam at the end of scanning is shown by a broken line. Conditions such as the dimensions and voltage of the system are set in advance so that the scanning area of the electron beam 11 and the scanning area of the electron beam 12 are smoothly connected in the vicinity of the center line 2c. FIG. 2(b) shows vertical deflection plates 41a-41b, -141
2, 42a, . . . , 42z are diagrams showing voltage waveforms. The figure shows the vertical deflection plate voltage for each vertical scanning period when the voltage of the shield electrodes 51 and 52 is set to, for example, 500V. At the start of vertical scanning, the vertical deflection plates 41a, . . . , 41
z, the voltage of 42a is OV, the vertical deflection plate 42b,...
The voltage of 42z is set to 500v. At this time, the electron beam 11 is deflected by the vertical deflection plate 41a, and the electron beam 12 is deflected by the vertical deflection plate 42a, respectively, to scan the top end of each scanning area. When the voltage of the vertical deflection plate 41a is continuously changed from OV to 500V, the deflection position of the electron beam 11 moves from the vertical deflection plate 41a to the vertical deflection plate 42b, and vertical scanning is performed by an amount equal to the arrangement pitch of the vertical deflection plates. It will be done. At the same time, the voltage of the vertical deflection plate 42b is increased to 50%.
When changing continuously from 0 to Ov, vertical scanning is performed by the electron beam 12 by the arrangement pitch of the vertical deflection plates. At this time, a voltage such that the voltage changes from Ov to negative and then returns to Ov is applied to the vertical deflection plate 41b and the vertical deflection plate 42a, respectively. As a result, the effect of optimally focusing the electron beams 11 and 12 in the vertical direction depending on the deflection can be applied to the electron beams 11 and 12, respectively. Immediately after the scanning of one pitch of the vertical deflection plate arrangement is completed, the voltage of the vertical deflection plate is immediately switched to perform scanning of the next one pitch. In the case of the electron beam 11, the voltage of the vertical deflection plate 41a after scanning is maintained at 500 square meters, and the voltage of the vertical deflection plate 41b is changed from Ov to 500 square meters to continue scanning. At this time, a voltage is applied to the vertical deflection plate 41c such that it once becomes negative from 0■ and returns to Ov again to optimally focus the electron beam. Similarly, the voltage for deflecting the electron beam and the voltage for focusing the electron beam are
The vertical deflection plates 41 are sequentially added to the vertical deflection plates one below each, and at the end of the effective scanning period, the vertical deflection plates 41
The voltage of a, ..., 41y is 500 V, and the vertical deflection plate 4
1z, 42a, 42b, ..., 42z voltage is O
V, and the electron beams 11,12 reach the bottom of each scanning area. Note that FIG. 2(b) depicts a waveform in which the voltage of all the vertical deflection plates once reaches 500 V after the end of the effective scanning period, and then returns to the voltage at the start of scanning. The purpose of this is to cause the electron beams 11 and 12 to travel straight in their respective emission directions in order to detect the position and current of the electron beam during the vertical retrace period. As described above, in the embodiment shown in FIG.
1.42 is used to perform vertical scanning. However, in carrying out the present invention, any deflection means may be used as long as it is capable of simultaneously deflecting two groups of electron beams directed in opposite directions. In addition, although Fig. 2 shows a method in which half of the scanning area of the fluorescent surface is sequentially scanned from above, it is also possible to use a method in which one scanning area is sequentially scanned from above and the other scanning area from below. Needless to say, it's a good thing. FIG. 3 is a diagram showing means for detecting the position and current of the electron beam and controlling the emission direction of the electron beam in the embodiment of FIG. 1. Electron beam position detection 〛electrode 7a,
7b, 7c, and 7d are perpendicular to the central axis 13 of the electron beam, and are arranged in the form of four divisions around the central axis 13. When the electron beam enters these position detection electrodes 78 to 7d, the amount of current flowing into each electrode is detected. By adjusting the voltages of the collimator electrodes 87a, 87b, 87c, and 87d that control the emission direction of the electron beam so that the current amount of the position detection electrodes 7a to 7d is all equal, the individual electron beams can be aligned parallel to the fluorescent surface. They can be fired parallel to each other. In addition, the position detection electrode 7
By comparing the total amount of current flowing into the electron beams 8 to 7d for each electron beam and applying feedback to each electron beam emitting means, it is possible to uniformly control the amount of current of the electron beam. In this manner, in the embodiment shown in FIG. 1, the electron beam position detection electrodes 7 are provided on the surface of the insulating support 53, corresponding to the electron beam emitting means provided at both ends. However, such an insulating support may be omitted in practicing the present invention. Furthermore, one set of electron beam position detection electrodes may be used in common for each of the two electron beams emitted from both ends. Further, the positions and currents of a plurality of electron beams may be detected every time during each vertical retrace period, or different positions of electron beams may be detected every time. Depending on the usage conditions, the position information of the electron beam may be stored in advance in a storage device such as memory.
It is also possible to configure the electron beam to be controlled by reading out this information. Next, another embodiment of the present invention shown in FIG. 5 will be described. FIG. 5 is a partially cutaway perspective view showing the schematic structure of a flat cathode ray tube according to an embodiment of the present invention. A plurality of vertical deflection plates 41, 42, one shield electrode 54, and a plurality of horizontal deflection plates 6 are arranged inside a flat vacuum container having a face portion 1 and a back panel portion 3, respectively. The inner surface of the face portion 1 is a fluorescent surface 2 coated with phosphors of the three primary colors red, green, and blue in a vertical stripe pattern. Linear cathodes 70, 74, electron beam extraction electrodes 71, 75, and electron beam shaping electrodes 7 are arranged at both vertical ends of the area sandwiched between the vertical deflection plates 41, 42 and the shielding electrode 54.
Electron beam emitting means consisting of 2.73 and 76.77 are respectively provided. These electron beam emitting means emit a plurality of electron beams 11, 12 arranged horizontally at predetermined intervals parallel to the fluorescent surface 2 and in opposite directions. The operation of the embodiment shown in FIG. 5 is substantially the same as that of the embodiment shown in FIG. The main difference is that multiple electron beams are extracted from one linear cathode, and the electron beam position detection electrode 7 and insulating support 53 shown in FIG.
is omitted. In order to prevent the positional shift of the electron beam, the linear cathode may be arranged with high precision. Its assembly is easier than the assembly in which a plurality of electron sources are regularly arranged as in the embodiment of FIG. Furthermore, if the driving conditions of the cathode are adjusted, it is possible to extract a uniform electron beam. Furthermore, since obstacles between the vertical deflection plates 41 and 42 are removed, there is an advantage that the scanning areas of the two groups of electron beams 11 and 12 can be easily and smoothly connected. Effects of the Invention 1 In the flat cathode ray tube of the present invention, two groups of electron beams directed in opposite directions simultaneously scan a half area of the fluorescent surface near each electron beam emitting means. The trajectory is shorter than that of the conventional example. As a result, it is possible to prevent the electron beam diameter from increasing due to the space charge effect, etc., and it is possible to uniformly and minutely control the electron beam spot diameter on the fluorescent surface. Therefore, according to the invention:
This has the effect of providing a flat cathode ray tube that can display large-screen, high-definition images.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view showing a schematic configuration of a flat cathode ray tube according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing how vertical scanning is performed in the embodiment of FIG. 1, 3 is a perspective view showing the means for controlling the emission direction of the electron beam in the embodiment shown in FIG. 1, FIG. 4 is a sectional view showing the schematic structure of a conventional flat cathode ray tube, and FIG. FIG. 6 is a partially cutaway perspective view showing the schematic structure of a flat cathode ray tube according to another embodiment of the invention, and FIG. 6 is a perspective view showing the schematic structure of a conventional flat cathode ray tube. Explanation of symbols 1... Face part, 2... Fluorescent surface, 3... Back panel part, 41.42... Vertical deflection plate, 51.52... Shield electrode, 6... Horizontal deflection plate, 7.Electron beam position detection electrode, 11.12...Electron beam 2 Figure '132 (Ku) No. 20 (jp') Certain figure Figure Tea diagram

Claims (1)

[Claims] 1. A fluorescent surface and a deflection device that deflects a plurality of electron beams emitted substantially parallel to the fluorescent surface toward the fluorescent surface and scans the emission direction of the electron beams. In a flat cathode ray tube comprising at least means, emitting means for the plurality of electron beams are provided at both ends of the deflecting means, and two groups of electron beams emitted from the emitting means in substantially opposite directions are A flat cathode ray tube characterized in that it is configured so that its fluorescent surfaces are simultaneously scanned. 2. The deflection means is provided with a fluorescent surface so as to sandwich the electron beam therebetween, and is composed of a plurality of deflection plates arranged at predetermined intervals in the emission direction of the electron beam. A flat cathode ray tube according to claim 1. 3. The voltage applied to each of the plurality of deflection plates is controlled so as to deflect each of the two groups of electron beams toward the fluorescent surface and at the same time optimally focus each of them on the fluorescent surface. 3. A flat cathode ray tube according to claim 2, characterized in that: 4. Means for further deflecting each of the electron beams deflected toward the fluorescent surface and scanning in a direction perpendicular to the emission direction is provided between the deflection means and the fluorescent surface. A flat cathode ray tube according to any one of claims 1 to 3, characterized in that: 5. Claims 1 to 3, characterized in that means for detecting the position and current of each electron beam is provided between the electron beam emitting means provided at both ends.
The flat cathode ray tube according to any of the preceding paragraphs. 6. The electron beam emitting means has means for adjusting the emitting direction of each electron beam, and emitting each electron beam based on information detected by the means for detecting the position and current of the electron beam. 6. A flat cathode ray tube according to claim 5, wherein the direction and current are controlled. 7. The means for detecting the position and current of the electron beam,
For at least one electron beam, it is composed of position detection electrodes arranged perpendicular to the emission axis of the electron beam and divided into four parts around the emission axis, and the current flowing into the position detection electrodes is all equal. 6. The flat cathode ray tube according to claim 5, wherein the emission direction of the electron beam is controlled so that the electron beam is emitted from the electron beam. 8. A color image display device characterized in that the flat cathode ray tube according to any one of claims 1 to 7 is used.