JP2754546B2 - Image display device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an image display device in a video device. 2. Description of the Related Art Conventionally, a cathode ray tube is mainly used as a color television image display device, but the cathode ray tube has a very long depth compared to a screen, and it is impossible to produce a thin television receiver. there were. In view of this, EL display elements, plasma display elements, liquid crystal display elements, and the like have recently been developed as flat display elements, but all of them are insufficient in performance such as luminance, contrast, and color reproducibility. Therefore, with the aim of displaying a color television image on a flat device using an electron beam capable of obtaining a high-quality image comparable to a cathode-ray tube, the screen on the screen is divided into matrix-shaped sections without any gaps. 2. Description of the Related Art There is an image display device that deflects and scans an electron beam for each of the sections to emit phosphors, thereby forming a color television image as a whole. Hereinafter, an example of the above-described conventional image display device will be described with reference to the drawings. FIG. 5 shows the internal structure of a conventional image display device. In FIG. 5, 1 is a back electrode, 2 is a line cathode as an electron beam source, 3a is an electron beam extraction electrode, 3b is a vertical focusing electrode, 4 is a vertical deflection electrode, 5 is a signal electrode, 6a and 6b are horizontal focusing electrodes, 7 is a horizontal deflection electrode, and 8 is an accelerating electrode. These components are housed in glass containers 9 and 22. Is a vacuum. The linear cathode 2 is stretched in the horizontal direction so as to generate an electron flow uniformly distributed in the horizontal direction. A plurality of such linear cathodes 2 (here, 2a to 2a) are provided at appropriate intervals.
(Only four of them are shown). These line cathodes are formed, for example, by coating a surface of a tungsten wire with an oxide cathode material. The back electrode 1 is made of a flat conductive material, and is provided in parallel with the linear cathodes 2a to 2d. Here, a back spacer 23 is further added, but this may be omitted. The extraction electrode 3a and the vertical focusing electrode 3b (not shown) are made of a conductive plate 11 having a slit 10 elongated in the horizontal direction, facing the back electrode 1 via the linear cathodes 2a to 2d. The slits 10 may be provided with bars at appropriate intervals in the middle, or may be formed substantially as slits in a row of a large number of through holes arranged at small intervals in the horizontal direction. A plurality of vertical deflection electrodes 4 are horizontally arranged at intermediate positions of the slits 10, and conductors 13a and 13b are provided on the upper and lower surfaces of the insulating substrate 12, respectively.
Is provided. The signal electrode 5 includes a plurality of conductive plates 15 having slits 14 elongated in the vertical direction and arranged in a horizontal direction at predetermined intervals. The horizontal focusing electrodes 6a and 6b are formed on a conductive plate 17 having a plurality of vertically elongated slits 16 at positions opposed to the slits 14 of the signal electrode 5.
It consists of. The horizontal deflection electrode 7 has a configuration in which a plurality of vertically elongated conductive plates 18 are arranged in a horizontal direction to form a fence, and in particular, a conductive plate 24 corresponding to the remaining margin of the slit 16 of the horizontal focusing electrodes 6a and 6b. Conductive plate at the position facing the part
18 are arranged respectively. The accelerating electrode 8 includes a plurality of conductive wires 19 provided at the same height as the vertical deflection electrode 4 in the horizontal direction. This may be a conductive plate or a rod. The screen 21 is formed by applying a phosphor 20 that emits light by irradiation with an electron beam to the inner surface of the glass container 9 and further adding a metal back layer (not shown) thereon. The operation of the conventional image display device configured as described above will be described below. First, a voltage is applied to the back electrode 1 and the back spacer electrode, and a voltage higher than the above voltage is applied to the extraction electrode 3a. Furthermore, if the voltage of the line cathode 2 is appropriately set, the electron flow emitted from the line cathode is accelerated toward the extraction electrode 3a. Further, if the voltage of the line cathode 2 is set higher than, for example, the extraction electrode voltage, the electric field on the surface of the line cathode becomes negative and the generation of electrons can be suppressed. Therefore, the linear cathode 2
By individually controlling the two voltages, the electron beam is repeatedly emitted from the upper linear cathode 2 in order from the upper line cathode 2 to the electron beams 2b, 2c,. Part of the electron beam generated in this manner and having a uniform distribution in the horizontal direction is extracted through the slit 10 of the extraction electrode 3a. Further, the vertical deflection electrode 4, the vertical focusing electrode 3b, and the extraction electrode 3a
In the space of the rectangular cross section formed by the above, vertical focusing and vertical deflection of the electron beam by the electrostatic lens effect and the electrostatic deflection effect are performed by appropriately controlling the respective voltages. Next, each electron beam is divided into a plurality of electron beams in the horizontal direction by the slits 14 of the signal electrode 5 and the voltage for the signal electrode 5 is controlled with time, so that an image for displaying a picture element is obtained. The passing amount of the electron beam is adjusted according to the signal. After that, each electron beam is focused by the electrostatic lens action by the horizontal focusing electrodes 6a and 6b, and at the horizontal deflection electrode 7, the adjacent conductive plates 18
By applying a deflecting voltage to the set of, it is deflected in the horizontal direction under the electrostatic deflecting action. Further, a high voltage (for example, 10 KV) is applied to the metal back layer of the screen 9, and the electron beam is accelerated toward the screen, collides with the metal back with high energy, and causes the phosphor to emit light. At this time, by applying a high voltage (for example, 10 KV) to the accelerating electrode 8, each conductive wire 19
An electrostatic lens having a divergence effect in the vertical direction is formed in the space between the two, and plays an auxiliary role of improving the vertical deflection sensitivity of the electron beam. In this way, when the television screen is vertically and horizontally dispersed in a matrix form, and a combination of the small sections 25 is formed, the electron beam separated as described above for each small section is one.
The entire screen can be configured on the screen by deflecting and scanning each electron beam only within the small section, one by one. Also, by controlling the R, G, B video signals corresponding to each picture element with the signal electrodes, a television moving image can be reproduced. Problems to be Solved by the Invention In the above configuration, in order to obtain a high-quality image comparable to a cathode ray tube, there are the following problems. First, when the whole screen is formed by connecting the small sections in a matrix, the trajectory of each electron beam is distorted due to variations in the positional accuracy and linearity of each electrode. Since the shapes are not arranged in such a rectangular shape, a joint between the small sections appears, and there is a problem that a horizontal line or a vertical line is seen in the image as a whole. In particular, the number of components of the vertical deflection electrode 4 and the accelerating electrode 8 increases according to the number of divisions in the vertical direction (the number of linear cathodes), and it is difficult to uniformly uniform the processing accuracy and the assembly accuracy of each component. . For example, if these electrodes are warped or bent, the vertical deflection sensitivity of the electron beam is not uniform in the horizontal direction, and the row of electron beam spots on the screen also bends, generating horizontal lines in the image. The second problem is that the vertical deflection electrode 4 is
For example, strict processing accuracy with a flatness of about 10 μm or less is required, and the number of parts is large, resulting in a very high cost. The third problem is that the acceleration electrode 8 is deformed by the electrostatic force. That is, since a very high voltage is applied to the accelerating electrode 8 with respect to the facing horizontal focusing electrode 6b, the conductive wire is deformed by the Coulomb force, and the vertical deflection sensitivity of the electron beam is made non-uniform. When the acceleration electrode is made of a material having high rigidity such as a conductive plate or a conductive rod and measures are taken to prevent electrostatic deformation, as in the second problem, the processing accuracy of parts is severe and the cost is extremely high. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an image display device that realizes high-quality images at low cost. Means for solving the problems To solve the above problems. The image display device of the present invention includes a flat screen coated with a phosphor, and a back electrode made of a conductive plate facing the screen, and the back electrode is provided in a space sandwiched between the back electrode and the screen. From side to screen,
A line cathode extending in the horizontal direction, a lead electrode formed of a conductive plate having a plurality of through holes, a signal electrode, a first focusing electrode for focusing in one of vertical and horizontal directions, a plurality of electrodes located on the same plane A horizontal deflection electrode composed of a plurality of conductive plates, and a vertical deflection electrode composed of a plurality of conductive plates located on the same plane, and the electrode located closest to the screen is the vertical deflection electrode. . Operation According to the present invention, the electron lens system having the above-described configuration makes it possible to reduce the horizontal focus diameter of the electron beam on the screen, thereby achieving good color purity. Further, according to the present invention, the horizontal deflection electrode is formed of a secondary comb-shaped conductive plate, thereby facilitating processing and assembling of components, reducing variations in component accuracy, and making electron beam horizontal deflection sensitivity uniform. As a result, a high quality image without vertical lines can be realized. Embodiment Hereinafter, an image display device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the internal configuration of an image display device according to an embodiment of the present invention. In FIG. 1, 51 is a back electrode, 52a to 52d are linear cathodes as an electron beam source, 53 is an electron beam extraction electrode, 54 is a signal electrode, 55 is a first focusing electrode, 56 is a second focusing electrode, 57 a and 57 b are horizontal deflection electrodes, 58
A and B are vertical deflection electrodes. These components are housed in glass containers 60 and 61, and the inside of the containers 60 and 61 is evacuated. The linear cathodes 52a to 52d are stretched in the horizontal direction so as to generate an electron current having a substantially uniform current density distribution in the horizontal direction. In the figure, only four of 52a, 52b, 52c, and 52d are shown). These line cathodes 52a to 52d are formed, for example, by coating an oxide cathode material on the surface of a tungsten wire. The back electrode 51 is made of a flat conductive material,
It is provided in parallel with 52a-52d. Leader electrode
Reference numeral 53 denotes a conductive plate which faces the back electrode 51 via the line cathodes 52a to 52d and has a row of through holes 62 provided at appropriate intervals in the horizontal direction on a horizontal line facing each line cathode. Through hole
Although 62 is circular in this embodiment, it may be elliptical or rectangular, or may be a slit-like electrode like the lead electrode of the above-mentioned conventional embodiment. The signal electrode 54 is composed of a row of vertically elongated conductive plates 64 that are arranged at predetermined positions at positions horizontally opposed to the through holes 62 in the extraction electrode 53, and each of the conductive plates 64 Has a similar through-hole 63 at a position facing the through-hole 62 of the extraction electrode 53. The shape of the through hole 63 may be elliptical or rectangular, or may be a vertically elongated slit like the signal electrode of the above-described conventional embodiment. The first focusing electrode 55 is formed of a conductive plate having a through hole 65 at a position facing each of the through holes 63 of the signal electrode 54. In the present embodiment, the shape of the through hole 65 is a rectangle or an ellipse that is long in the horizontal direction, and functions as a vertical focusing lens. Second
The focusing electrode 56 has a slit hole 66 vertically connected to a position facing the through hole 65 of the first focusing electrode 55. Instead of the slit hole 66, a rectangle or an ellipse which is long in the vertical direction may be used, and both work as a horizontal focusing lens. Horizontal deflection electrode 57
A and B are composed of conductive plates 68 and 69 connected by two comb-teeth-shaped ends which mesh with each other via a space as appropriate on the same plane, and are provided with horizontal deflection electrodes 57A and 57B. The space 67 formed therebetween is opposed to the through slit hole 66 of the second focusing electrode 56. The vertical deflection electrodes 58a and 58b are formed by meshing two conductive plates connected at their ends as shown at 70 and 71, that is, two comb-teeth-shaped conductive plates at appropriate intervals on the same plane. For example, for the electron beam 72, the lower conductive plate 70 and the upper conductive plate 71 form a pair of vertical deflection electrodes. The screen 73 is configured by applying a phosphor 74 that emits light by irradiation with an electron beam to the inner surface of the glass container 60 and adding a metal back layer (not shown) thereon. The operation of the image display device configured as described above will be described. First, a voltage V ₁ is applied to the back electrode 51 and a voltage V ₂ higher than V ₁ is applied to the extraction electrode 53. Further, the line cathode is heated, and V ₁ <V ₀ with a heater current flowing to facilitate electron emission.
<By applying a V ₂ becomes appropriate voltage V ₀ to the linear cathodes 52 b, the electric field of the linear cathodes surface electron stream is released as positive, it is accelerated toward the extraction electrode 53. Further, for example, when a voltage V ₀ satisfying V ₀ > V ₂ is applied to the line cathode 52a, the electric field on the surface of the line cathode becomes negative, and emission of electrons can be suppressed. Therefore, by controlling the voltage of the line cathode individually,
The electron beam is repeatedly emitted in the order of 52 b, 52 c,... In order from 52 a so that the electron beam is emitted for a certain period of time. Can be generated. The above-mentioned sheet-like electron beam is then divided into a plurality of pieces by the through-hole 62 of the extraction electrode 53 in the horizontal direction, and reaches a through-hole 63 of the signal electrode 54 as a further large number of electron beam rows. to the voltage V ₃ of the signal electrodes 54 V _3> V ₀ Tosureba electron beam passes through, V ₃ <V ₀ Tosureba electron beam can no longer pass loses kinetic energy. Therefore, by time control of the V _3, to adjust the electron beam passing amount each electron beam individually in accordance with a video signal for displaying picture elements. The electron beam that has passed through the signal electrode 54 is then passed to the first focusing electrode.
55, reaches the second focusing electrode 56, and is focused and shaped by the electrostatic lens effect of the through hole 65 and the slit hole 66, and then between the adjacent conductive plates of the horizontal deflection electrodes 57a and 57b and vertical deflection. Electrostatic deflection is performed horizontally and vertically by a potential difference (referred to as a deflection voltage) provided between the adjacent conductive plates 70 and 71 of the electrodes 58a and 58b. Further, a high voltage (for example, 10 KV) is applied to the metal back layer of the screen 73, and the electron beam is accelerated to a high energy and collides with the metal back, causing the phosphor to emit light. When the television screen is vertically and horizontally divided into a matrix to form an aggregate of small sections 75, the electron beams separated as described above correspond to each of the small sections, and the electron beam is divided into the small sections. By deflecting and scanning only within the minute, the entire screen can be projected on the screen. In addition, by controlling the RGB video signal corresponding to each picture element with time using the signal electrode voltage as described above, a television moving image can be reproduced. As described above, this embodiment and the embodiment shown in FIG.
On the basic configuration and the conventional example shown in the figure, the configuration is almost the same, but a remarkable difference is that the vertical deflection electrodes 58a and 58b are located behind the electrode groups 53 to 57, that is, on the screen side, and The accelerating electrode 8 used in the conventional embodiment is omitted at all, and the vertical deflection electrodes 58a and 58b are
And 71, the structure is such that a comb-shaped conductive plate is engaged. A remarkable difference between the present embodiment and the embodiment shown in FIG. 2 is that a second focusing electrode 56 is provided between the first focusing electrode 55 and the horizontal deflection electrodes 57a and 57b to focus the electron beam. The shaping is further improved. In the embodiment of FIG. 2, the horizontal deflection electrode 31 has the elongated conductive plates 40 individually arranged as shown in FIG. There are two points that the conductive plates in the shape of a mesh are engaged. Next, with respect to the embodiment of FIG. 2, the above-mentioned features of this embodiment will be described in detail with reference to FIGS. Electron beam 72 extracted by extraction electrode 53
After being limited by the signal electrode 54 to a beam amount corresponding to the signal, the beam is focused and shaped by the voltage of the focusing electrode and the shape of the hole. One focusing electrode 30 as shown in the example
It has been found that focusing alone has limitations in focusing and shaping, and there is a limit in reducing the spot diameter of the electron beam on the screen 73. Therefore, the present inventors have devised a method of adding a second focusing electrode 56 and focusing and shaping with two focusing electrodes 55 and 56. FIG. 3a shows a sectional view of a single focusing electrode and a beam orbit and a spot diameter 76, and FIG. 3b shows a sectional view of a two focusing electrode and a beam orbit and a spot diameter 77 of the present embodiment. Show. As shown in FIG. 3A, if the focusing and shaping of the electron beam by the focusing electrode is insufficient, the spot diameter 76 on the screen 43 becomes large. stripe
Exceeding 78 causes the phosphors 79 and 81 of other colors to illuminate, causing a deterioration in color purity. As shown in FIG. 3B, when two focusing electrodes 55 and 56 are provided and focusing and shaping are sufficiently performed as in the present embodiment, the spot diameter 77 becomes small, and the phosphor (eg, 80) which is supposed to emit light is desired. Only glowed, and the color purity improved. Next, a method for manufacturing the horizontal deflection electrode 57 will be described. As described in the description of the embodiment, in order to deflect the electron beam 72 in the horizontal direction by the horizontal deflection electrode, two opposing conductive plates sandwiching the electron beam must be electrically separated. . However, as shown in FIG. 2, when the divided conductive plates 40 are assembled into the horizontal deflection electrode 31, it is difficult to assemble and the accuracy tends to vary. In addition, it is necessary to take out the electrode terminals one by one outside the container or connect them inside. In order to solve such problems, as shown in FIG. 1, the horizontal deflection electrodes 57a and 57b are constituted by the conductive plates 68 and 69 which are finally separated into two. As a specific manufacturing method, first, a bar or the like is provided as appropriate, and as a single piece which is partially connected, processed and manufactured by etching, and after laminating and fixing the electrode groups 53 to 58 via insulating spacers, By removing unnecessary bars by a method such as laser beam cutting, a conductive plate finally separated into two plates can be manufactured inexpensively and accurately. FIG. 4 shows a method of manufacturing the horizontal deflection electrodes 57a and 57b. FIG. 4 is a plan view of the horizontal deflection electrode. Initially,
The horizontal deflection electrode is formed by processing one conductive plate into an etching pattern as shown in FIG. 4, and 68 and 69 are connected by a thin bar. After being laminated and fixed with other electrode groups,
As shown in FIG. 4, a process is used in which a cross section (indicated by x in the figure) is cut and removed by laser beam processing and separated into two conductive plates. In this way, errors do not easily occur in the parallelism, interval, and flatness of the comb teeth, and there is no need to connect each of the two conductive plates to which a voltage is to be applied. As described above, according to the present invention, the horizontal spot diameter on the screen can be reduced, and good color purity can be obtained. Further, according to the present invention, by forming the horizontal deflection electrodes in a comb shape, processing is facilitated, processing and assembling of the electrodes with high precision are enabled, and there is no vertical line, high uniformity and high quality image. Can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially exploded perspective view showing the internal structure of an image display device according to an embodiment of the present invention, and FIG. 2 is a diagram showing the internal structure of the image display device invented prior to the present invention. FIG. 3A is a horizontal sectional view showing the horizontal cross section of the configuration of FIG. 2, its electron beam trajectory and the spot diameter on the screen, and FIG. 3B is a horizontal cross section of the configuration of the present embodiment. FIG. 4 is a horizontal sectional view showing a cross section, an electron beam trajectory, and a spot diameter on a screen, FIG. 4 is a plan view showing a method of manufacturing a horizontal deflection electrode of this embodiment, and FIG. It is a partial exploded perspective view showing a configuration. 51: Back electrode, 52a, 52b, 52c, 52d ... Wire cathode, 53
... Extraction electrode, 54... Signal electrode 55... First focusing electrode 56... Second focusing electrode 57 a and 57 b horizontal deflection electrode 58 a 58 b vertical deflection electrode 60 , 61 …… Glass container, 73 …… Screen.

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Tatsuaki Watanabe 1006 Kadoma, Kazuma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. Inside (72) Inventor Tomohiro Sekiguchi 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. References JP-A-1-130453 (JP, A) JP-A-61-181044 (JP, A) JP-A-59-91642 (JP, A) JP-B-58-42583 (JP, B2) JP-B-58 −32897 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01J 31/12 H01J 29/74 H01J 29/62

Claims (1)

(57) [Claims] A screen on a plane coated with a phosphor and a back electrode made of a conductive plate facing the screen, and a space sandwiched between the back electrode and the screen, in order from the back electrode side to the screen,
A linear cathode extending in the horizontal direction, a lead electrode formed of a conductive plate having a plurality of through holes, a signal electrode, a first focusing electrode for focusing in one of vertical and horizontal directions, and focusing of the first focusing electrode A second focusing electrode that focuses in a direction different from the direction in which the light is emitted, a horizontal deflection electrode composed of a plurality of conductive plates located on the same plane, and a vertical deflection electrode composed of a plurality of conductive plates located on the same plane. An image display device characterized by the above-mentioned.