JPH0589803A - Image display device - Google Patents

Abstract

PURPOSE:To provide an image display device free of image quality deterioration resulting from varying bombardment position on fluorescent substance with an electron beam by introducing an electrode fixed configuration in which possible potential variation is eliminated in the neighborhood of an electron hold down screw due to electric insulation after the image display is commenced. CONSTITUTION:An electrode block 24 is secured to a back plate 1 using an electrode hold down countersunk screw 34, wherein the block is fastened with the aid of a metal electrode hold down bushing 33. The block 24 is insulated from the back plate 1 with a ceramic spacer 32, wherein the spacing is kept constant, while a ceramic bushing 31 is used to insulate the hold down screw 34 from the back plate 1. A hexagonal nut 35 is set as mating with this hold down screw 34 and fastened as shown in the attached illustration so as to secure electrodes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device in video equipment.

[0002]

2. Description of the Related Art Heretofore, a cathode ray tube has been mainly used as a color television image display element. However, the cathode ray tube has a very long depth relative to the width of the screen, and it is difficult to manufacture a thin television receiver. It was impossible.

Therefore, EL display elements, plasma display elements, liquid crystal display elements, etc. have been developed as flat plate type display elements for realizing a thinner television receiver.
All of them were inferior in terms of performance such as brightness, contrast and color reproducibility as compared with the cathode ray tube.

Therefore, for the purpose of displaying a high-quality image similar to that of a cathode-ray tube with a flat plate type apparatus using an electron beam, the screen on the screen is divided into matrix-like sections without any gaps, and each section is divided into sections. Further, an image display apparatus has been developed in which a color television image is formed as a whole by deflecting and scanning an electron beam to cause a phosphor to emit light.

An example of the above-mentioned conventional image display device will be described below with reference to the drawings. FIG. 3 shows the configuration of a conventional image display device. In FIG. 3, 1
Is a back electrode, 2 is a line cathode as an electron beam source, 3 is an electron beam extraction electrode, 4 is a signal electrode, 5 and 6 are focusing electrodes, 7 is a horizontal deflection electrode, and 8 is a vertical deflection electrode. The components 1 to 8 are sandwiched between a front glass container 9 whose front surface is made of glass and whose inner surface is coated with a phosphor, and a rear plate 10 which closes a rear opening of the front glass container 9. It is housed in the space and the inside of the front glass container 9 is evacuated.

The line cathode 2 is formed by coating an oxide cathode material on the surface of a tungsten wire, for example, and is horizontally stretched so as to generate an electron flow uniformly distributed in the horizontal direction. A plurality of line cathodes 2 are provided in the vertical direction at appropriate intervals. The back electrode 1 is made of a flat conductive material, and is arranged in parallel behind the line cathode 2.

The lead-out electrode 3 is composed of a conductive plate arranged so as to face the front surface of the back electrode 1 through the line cathode 2, and a plurality of through holes 11 are formed in a horizontal line portion of the conductive plate facing each line cathode 2. Are arranged in the horizontal direction at appropriate intervals. Through hole 11
Although it is formed in a circular shape in the illustrated example, it may be formed in an oval shape, a rectangular shape, or a slit shape. The signal electrode 4 is a through hole of the extraction electrode 3.
Each of the conductive plates 12 has a row of vertically elongated conductive plates 12 arranged at a predetermined interval and facing each other, and each conductive plate 12 faces the through hole 11 of the extraction electrode 3. A circular through hole 13 is provided at the position. The shape of these through holes 13 may be elliptical or rectangular as in the case of the through holes 11, or may be a vertically elongated slit shape.

The focusing electrode 5 is composed of a conductive plate having through holes 14 of the signal electrode 4 and through holes 14 each having a horizontally long rectangular hole at a position facing each other. The shape of the through hole 14 may be circular, elliptical, or slit-shaped. The other focusing electrode 6 is made of a conductive plate in which vertically elongated slit holes 15 facing each other in each column of the through holes 14 of the focusing electrode 5 are arranged in parallel in the horizontal direction. The slit holes 15 may have other shapes such as a round hole, an ellipse, and a rectangular shape.

The horizontal deflection electrode 7 has two comb-shaped conductive plates 16 and 17 formed by connecting the base end portions of the comb-tooth-shaped portions arranged in parallel in the horizontal direction in common to the horizontal connecting portion on the same plane. Spaced between the comb-tooth-shaped portions of the conductive plates 16 and 17 that are meshed with each other is the focusing electrode 6 respectively.
It is arranged so as to face the slit-shaped through hole 15. The vertical deflection electrode 8 is formed by commonly connecting the base end portions of the comb-shaped portions arranged in parallel in the vertical direction to the vertical connecting portion 2
The comb-shaped conductive plates 19 and 20 are made to face each other on the same plane, and
The meshes are engaged at appropriate intervals.

The screen 21 is constructed by applying a phosphor 22 that emits light by irradiation of an electron beam to the inner surface of the glass container 9 and adding a metal back layer (not shown) thereon. Further, the extraction electrode 3, the signal electrode 4, the focusing electrodes 5 and 6, the horizontal deflection electrode 7 and the vertical deflection electrode 8 described above are respectively joined by an insulating adhesive to form an integral electrode block 24. There is.

Further, the fixing structure of the electrode block 24 and the back electrode 1 will be described with reference to FIGS. 4 and 5. FIG. 4 is an exploded perspective view of an essential part showing a fixing structure of the electrode block 24 and the back electrode 1 of the conventional image display device, and FIG. 5 is a sectional view thereof. Reference numeral 30 denotes an electrode fixing screw that attaches the electrode block 24 to the back electrode 1. Reference numeral 31 is a ceramic bush for insulating the electrode fixing screw 30 and the electrode block 24. Reference numeral 32 is a ceramic spacer that insulates the electrode block 24 and the back electrode 1 and keeps a constant distance so that the wire cathode 2 can enter.

The operation of the image display device configured as described above will be briefly described again with reference to FIG. 3. First, a heater current for facilitating electron emission is applied to the line cathode 2 to heat it. Appropriate voltage is applied to the back electrode 1, the line cathode 2 and the extraction electrode 3 in a heated state to emit a sheet electron beam from the surface of the line cathode 2. The sheet-like electron beam is split into a plurality of electron beam streams 23 by the through holes 11 of the extraction electrode 3. The passing amount of the electron beam flow 23 is individually adjusted by the signal electrode 4 in accordance with the video signal applied to the signal electrode 4.

Next, the electron beam that has passed through the signal electrode 4 is focused and shaped by the electrostatic lens effect of the through holes 14 and 15 of the focusing electrodes 5 and 6, and then the conductive plate adjacent to the horizontal deflection electrode 7 is formed.
It is deflected horizontally and vertically by the potential difference applied to the conductive plates 19 and 20 adjacent to 16 and 17 and the vertical deflection electrode 8.
Further, a high voltage (for example, 10 kV) is applied to the metal back layer of the screen 21, the electron beam is accelerated to high energy and collides with the metal back, causing the phosphor to emit light.

When a television screen is vertically and horizontally divided into a matrix to form an assembly of subsections 25, one electron beam separated as described above is associated with each subsection 25. The electron beam is deflected only within each subsection 25,
By scanning, the entire screen can be displayed on the screen. Further, by controlling the RGB video signal corresponding to each pixel with the signal electrode 4, a television moving image can be reproduced.

[0015]

In the above structure, the conventional image display device has the following problems.
Electrons collide with the surface of the ceramic bush 31 shown in FIG. 4 after the start of image display. At this time, secondary electrons are emitted on the surface of the ceramic bush 31 and the surface potential rises. This potential rise reaches several kV within a few minutes after the start of image display, so the potential distribution near the ceramic bush 31 changes. As a result, within a few minutes after the start of image display, the collision position of the electron beam on the phosphor changes, especially near the ceramic bush 31, causing image quality deterioration.

In view of the above problems, the present invention is to provide an image display device capable of displaying a high quality image even at the start of image display.

[0017]

To achieve the above object, an image display device of the present invention is an image display device in which a back electrode and an electrode block are arranged between a front glass container and a back plate as described above. The fixing structure of the electrode block and the back electrode is configured as follows. That is, a ceramic bush is arranged on the back electrode side, a metal electrode fixing bush is arranged on the electrode block side, a nut is arranged behind the ceramic bush, and an electrode fixing flat head screw is attached to the head of the electrode block. Insert the electrode block through the back electrode so that it does not protrude from the outer surface, and fasten the nut to the electrode fixing flat screw, so that the electrode fixing flat screw is insulated by the ceramic bush, and the electrode block and the back surface are insulated. The electrodes are fixed.

[0018]

According to the image display device of the present invention, the ceramic bush which causes a potential change due to electron collision at the start of image display is arranged on the back electrode side, and the head of the electrode fixing flat head screw does not project to the electrode block surface. Therefore, the potential fluctuation in the vicinity of the plate screw for fixing the electrode does not occur after the image display is started. Therefore, there is no change in the collision position of the electron beam with the phosphor, and the image quality is not deteriorated.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image display apparatus according to an embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is an exploded perspective view of an essential part showing a fixing structure of an electrode block and a back electrode of an image display device according to this embodiment, and FIG. 2 is a sectional view thereof. In the image display device of the present embodiment, a front glass container 9 having a front surface made of glass and a phosphor coated on the inner surface thereof and a rear plate 10 for closing a rear opening of the front glass container 9 face each other. A rear electrode 1 made of a single conductive plate, a plurality of line cathodes 2 and a drawer made of a single or a plurality of conductive plates are arranged in a space between the front glass container 9 and the back plate 10. The electrode 3, the signal electrode 4, the focusing electrode 5, the horizontal deflection electrode 7, and the vertical deflection electrode 8 have a basic configuration in which an electrode block 24 formed by stacking them on the front and rear sides is arranged. Since the configuration is the same as the configuration of the conventional device shown in FIG. 3, its description is omitted to avoid duplication.

In FIG. 1 and FIG. 2, 31 is a ceramic bush, which is a screw insertion hole 1a formed in the back electrode 1.
Is fitted into. Reference numeral 32 denotes a ceramic spacer which is interposed between the electrode block 24 and the back electrode 1 to insulate the electrode block 24 and the back electrode 1 from each other and to keep the gap constant. 33 is an electrode block 24
Is a metal electrode fixing bush arranged in front of the opening of the screw insertion hole 24a, 34 is an electrode fixing flat head screw, 35 is a hexagon nut arranged behind the ceramic bushing 31, and the electrode fixing flat head screw 34 is fixed to the metal electrode. Bush 33 to electrode block 24
The back electrode 1 and the electrode block 24 are fixed by being inserted through the screw insertion hole 24a, the ceramic spacer 32, and the ceramic bush 31 and fastened to the nut 35.

The center portion of the metal electrode fixing bush 33 is recessed in a mortar shape, and the electrode fixing flat head screw 34 and nut 35 are used.
When it is fastened, the head portion 34a is completely immersed. Further, when the back electrode 1 and the electrode block 24 are fixed, the ceramic bush 31 insulates the plate screw 34 for fixing the electrode from the back electrode 1.

In the image display device of the present embodiment having the above-described structure, the ceramic bush 31 that causes a potential change due to electron collision after the image display is started is arranged on the back electrode 1 side. Electric potential fluctuations in the vicinity of the electrode fixing flat head screw 34 do not occur. Also, the head 34 of the electrode fixing flat head screw 34
Since a has a structure that does not protrude to the outer surface of the electrode block 24, the trajectory of the electron beam traveling from the electrode block 24 to the phosphor is not affected by the head 34a of the electrode fixing screw 34.

[0023]

As described above, according to the present invention, the ceramic bush is arranged on the back electrode side, the metal electrode fixing bush is arranged on the electrode block side, and the nut is arranged behind the ceramic bush. , The electrode bush is screwed through the electrode block from the outer surface of the electrode block so that the head does not protrude from the outer surface of the electrode block, and the nut is fastened to the electrode dish flat screw, whereby the ceramic bush Since the electrode block and the back electrode are fixed in a state in which the electrode fixing countersunk screw is insulated by, the collision position of the electron beam in the vicinity of the electrode fixing screw on the phosphor does not fluctuate when the image display is started. It is possible to provide an image display device that does not cause deterioration of image quality at the start of display.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a main part of an image display device according to an embodiment of the present invention.

FIG. 2 is a sectional view thereof.

FIG. 3 is an exploded perspective view of essential parts showing the configuration of a conventional image display device.

FIG. 4 is an exploded perspective view of a main part of a conventional image display device.

FIG. 5 is a sectional view thereof.

[Explanation of symbols]

 1 Rear Electrode 2 Wire Cathode 3 Extraction Electrode 4 Signal Electrode 5 Focusing Electrode 6 Focusing Electrode 7 Horizontal Deflection Electrode 8 Vertical Deflection Electrode 9 Front Glass Container 10 Rear Plate 24 Electrode Block 31 Ceramic Bushing 32 Ceramic Spacer 33 Metal Electrode Fixing Bushing 34 Electrode Fixing Flat head screw 34a Electrode fixing flat head screw head 35 Nut

Claims (1)

[Claims] 1. A front glass container in which a front glass container whose front surface is formed of glass and whose inner surface is coated with a phosphor and a rear plate which closes a rear opening of the front glass container are arranged to face each other. A back electrode made of a single conductive plate, a plurality of line cathodes, a lead electrode made of a single or a plurality of conductive plates, a signal electrode, a focusing electrode, and a horizontal deflection electrode in a space sandwiched between the back plate. And an electrode block in which vertical deflection electrodes are superposed on each other in the front and back, a ceramic bush is arranged on the back electrode side, and a metal electrode fixing bush is arranged on the electrode block side, while the ceramic bush is arranged. Place a nut behind the electrode block and insert an electrode fixing flat screw across the electrode block from the electrode block so that the head does not protrude from the outer surface of the electrode block. The image display device is characterized in that the electrode block and the back electrode are fixed in a state where the electrode fixing plate screw is insulated by the ceramic bush by fastening the nut to the electrode fixing plate screw.