JPH0427661B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a flat cathode ray tube used in an image display device and a method for driving the same.

Conventional structure and its problems Conventionally, as a flat cathode ray tube, JP-A-143063 was used.
JP-A-55-33734, etc. have been proposed. This is shown in FIG. In this figure, from the back to the front, the back electrode 1, the linear cathode 2 as an electron beam source, the beam extraction electrode 3, the vertical focusing and deflection electrode 4, the first shield electrode 5, and the electron beam flow control electrode 6. , a second shield electrode 7, a horizontal focusing and deflection electrode 8, a third shield electrode 9, an electron beam acceleration electrode 10 and a screen 11 are arranged. A linear cathode 2 serving as an electron beam source is stretched horizontally so as to generate a linear electron beam in the horizontal direction, and a plurality of such cathodes 2 are provided vertically at appropriate intervals. . In this embodiment, it is assumed that 15 pieces are provided. These cathodes 2 are constructed by applying an oxide cathode material to the surface of a tungsten wire having a diameter of 10 to 20 μm, for example. In order to extract the beam from the cathode 2 toward the beam extraction electrode 3, the potential of the back electrode 1 is lower than that of the cathode 2, and the potential of the beam extraction electrode 3 is higher than that of the cathode 2. The electron beam emitted from the cathode 2 in this manner passes through the aperture 3' of the beam extraction electrode 3 and advances to the region of the vertical focusing/deflection electrode 4. A plurality of vertical focusing/deflecting electrodes 4 are disposed between each of the apertures 3' of the beam extraction electrode 3, and are used to direct the electron beam in the vertical direction using an electrostatic lens formed between the first shield electrode 5 and the next first shield electrode 5. At the same time, a vertical deflection voltage is applied between the facing vertical focusing/deflecting electrodes 4 to deflect the electron beam in the vertical direction. In this configuration example, the electron beam from one cathode 2 is vertically deflected by 16 horizontal lines. Therefore, when all 15 cathodes 2 are driven, the electron beam is deflected to draw 240 horizontal lines on the screen.

Next, the control electrodes 6 are composed of strip-shaped conductive plates each having a long slit in the vertical direction, and a plurality of control electrodes 6 are arranged in parallel in the horizontal direction at predetermined intervals. Each of the control electrodes 6 extracts the electron beam by dividing it into one picture element in the horizontal direction, and controls the amount of electron beam passing through the electron beam in accordance with a video signal for displaying each picture element. Therefore, if 320 control electrodes 6 are provided, one horizontal
320 pixels can be displayed per line.
Also, in order to display images in color, each picture element is R,
Display is performed using three-color phosphors of G and B, and the R, G, and B video signals are applied to each control electrode 6. Furthermore, one line of video signals is simultaneously applied to each of the control electrodes 6, and one line of video is displayed simultaneously.

The horizontal focusing/deflection electrode 8 is made up of a plurality of conductive plates arranged vertically at intermediate positions between the slits of the control electrode 6, and a horizontal deflection voltage is applied between each conductive plate. The electron beam for each picture element is deflected in the horizontal direction, and the R, G, and B phosphors are sequentially irradiated on the screen to emit light. In this embodiment, the deflection range is the width of one picture element for each electron beam. At the same time, the electron beams for each picture element divided horizontally are focused in the horizontal direction.

Note that the first, second, and third shield electrodes 5, 7, 9
are conductive plates each having a plurality of vertically long slits facing the slits of the control electrode 6.

The electron beam accelerating electrode 10 is composed of a plurality of conductive plates provided horizontally at the same position as the vertical focusing/deflecting electrode 4, and simultaneously accelerates the electron beam and expands the vertical deflection. ing.

The screen 11 is constructed by coating the back surface of a glass plate 21 with a phosphor 20 that emits light when irradiated with an electron beam, and adding a metal back layer (not shown). The phosphors 20 are provided with one set of phosphors of three colors R, G, and B for each slit hole of the control electrode 6, that is, for each beam divided in the horizontal direction. It is applied in vertical stripes. In FIG. 1, the broken lines drawn on the screen 11 indicate divisions in the vertical direction corresponding to each of the plurality of line cathodes 2, and the two-dot chain lines correspond to each of the plurality of control electrodes 6. Indicates the horizontal division displayed.

The feature of the flat cathode ray tube configured as described above is that it uses multiple line cathodes and multiple control electrodes, and deflects the electron beam vertically and horizontally for each block, producing one entire image on the screen. It is synthesized into

However, the problem is that since the images are combined into one on the screen, each electrode requires high dimensional accuracy and assembly accuracy in order to avoid deterioration of image quality at the joints of each block, and the drive circuit. Stability is highly required. This situation is shown in the second
This will be explained using figures.

FIG. 2 is a vertical sectional view of the conventional example shown in FIG.
The same parts as in FIG. 1 are given the same reference numerals. The locus of the electron beam 25 shown here is that during operation of one embodiment in which the voltage of the video signal applied to the electron beam flow control electrode 6 is lowered. In FIG. 1, the entire screen is constructed by deflecting the electron beam 25 from each cathode in 16 steps in the vertical direction (arrow V) and keeping the scanning line interval constant.

At this time, the joint between the vertical scanning areas of each cathode 2, 2', . . . , the position V1-16 of the electron beam 25 on the screen in FIG. It is necessary that the distance between the two cathodes 2, 2', . . . That is, when the distance is smaller than each vertical scanning interval, two bright lines are close to each other or overlap, so a bright horizontal line is generated in that area. On the other hand, when the distance is larger than each vertical interval, the bright line appears to be missing, resulting in a black horizontal line. Therefore, the trajectory of the electron beams 25, 25', . . . with respect to each cathode 2, 2', . . . must be strictly controlled. For this purpose, it is necessary that the dimensional accuracy and assembly and arrangement accuracy of each electrode be kept highly accurate and uniform. Uniformity is also required for the drive circuit for each electrode. However, it is very difficult to maintain uniformity of the drive circuit due to variations in circuit components and changes over time.

OBJECTS OF THE INVENTION In view of the above-mentioned drawbacks, the present invention aims to solve the problem of image composition in the above-mentioned flat cathode ray tube, especially the horizontal lines that tend to occur at the top and bottom seams of each block.
That is, the present invention provides a flat plate cathode ray tube and a method for driving the same, in which the vertical deflection amplitude of each cathode is stabilized.

Structure of the Invention In order to achieve the above object, the present invention provides an aperture corresponding to the number of horizontal scanning lines in an electrode, for example, a first shield electrode, which is arranged after vertically deflecting an electron beam in a flat cathode ray tube, and the electron beam passes through the aperture. The vertical amplitude and beam position of each cathode are detected based on the beam transmittance, and the vertical deflection circuit is controlled using this detection signal.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 3 shows a perspective view of the first shield electrode 5 and control electrode 6 in the electrode structure of the flat cathode ray tube according to the present invention, and FIG. 4 shows a vertical sectional view thereof. The rest of the configuration is completely the same as that of the conventional example shown in FIG. 1, so it will be omitted. Electrodes 5' and 6' are provided outside the horizontal effective screen of the first shield electrode 5 and control electrode 6, and are separated from the electrodes within the effective screen. At least the same number of apertures 5'' as there are scanning lines, in the embodiment described above, 16 apertures 5'' are provided in the apertures 5''. Although the position of the aperture 5'' does not require strict alignment, it is necessary to arrange it so that the center of the beam passing through the aperture is at the correct position on the screen.On the other hand, the control electrode 6 The electrode 6' separated from the electrode 6' may or may not be provided with an aperture.Normally, an aperture is not provided.

In the above electrode configuration, as an initial adjustment, the electron beam is made to be incident on the correct position on the screen, and the amount of beam flowing into the separated first shield electrode 5' and the separated control electrode 6' is adjusted in each horizontal direction. The detectors 41A and 41B detect each scan, and the comparator 42 calculates the difference or ratio between them and inputs the result to the memory circuit 44. When the above input is completed, the data is read out from the memory circuit 44 in synchronization with the vertical and horizontal scanning, and by turning the switch 43 to b, the subsequent output from the comparator 42 and the output from the memory circuit 44 are read out to the comparator 45. When a difference occurs, the difference signal is input to the vertical deflection control circuit 46, and the voltage applied to the vertical focusing/deflection electrode 4 is controlled so as to correct the electron beam position.

As a result, the same driving conditions as at the time of initial adjustment are always provided, and the electron beam can be made to enter a precise position on the screen. By performing this for each cathode, images can be reproduced without horizontal lines appearing at the joints.

In the above embodiment, the beam position is detected at the positions of the first shield electrode 5 and the control electrode 6, but it should be noted that any electrode located closer to the screen than the vertical focusing/deflection electrode 4 may be used. Not even. In this case, an opening may be formed in the electrode on the electron gun side.

Effects of the Invention As described above, in the present invention, a regular screen is prepared in advance from the separated first shield electrode 5' and the control electrode 6' having at least the same number of openings as the number of horizontal scanning lines provided outside the effective screen. By detecting and memorizing the beam position that the beam reaches above, and then constantly comparing this memorized signal with the beam position signal and controlling the beam position, the position on the screen where the beam reaches is always accurately determined. can be retained. Therefore, the generation of horizontal lines at the deflection boundaries for each cathode can be prevented, and a seamless high-quality image can be obtained. Note that when the present invention is utilized, poor electrode precision can be compensated for in the drive circuit system, making manufacturing easier.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the structure of a conventional flat cathode ray tube, FIG. 2 is a cross-sectional view of the same, FIG.
The figure is a diagram of the control circuit. 1...Back electrode, 2...Striated cathode, 3...
Beam extraction electrode, 4... vertical focusing/deflection electrode,
5...First shield electrode, 6...Electron beam flow control electrode, 7...Second shield electrode, 8...Horizontal focusing/deflection electrode, 9...Third shield electrode, 10...
...Electron beam accelerating electrode, 11...Screen, 2
5... Electron beam, 41A, 41B... Beam amount detector, 42, 45... Comparator, 44... Memory circuit, 46... Vertical deflection control circuit.

Claims (1)

[Scope of Claims] 1. A plurality of horizontally long electron beam sources arranged vertically, means for vertically deflecting each electron beam, means for controlling the electron beam flow, and a screen formed with phosphor. and at least two electrodes for detecting the position of the electron beam are provided outside the effective screen of at least two of the plurality of electrodes arranged in the path through which the electron beam passes after being vertically deflected, and the first electrode through which the beam passes is A flat cathode ray tube characterized by having an opening. 2 The electrode for detecting the electron beam position is electrically separated within the effective screen and outside the effective screen, and the first electrode through which the beam passes has at least the same number of apertures in the vertical direction as the number of horizontal scanning lines. A flat cathode ray tube according to claim 1, characterized in that: 3. Regular 8 on the screen from the electron beam position detection electrode placed outside the effective screen of the flat cathode ray tube.
Detects the signal when the electron beam is incident at the position and inputs it to the memory circuit. During actual operation, the signal from the beam position detection electrode and the signal input to the memory circuit are compared, and if an error occurs, it is corrected. A method for driving a flat cathode ray tube, characterized in that the voltage of a vertical deflection control circuit is controlled by a difference signal.