JPH0426177B2 - - Google Patents

Description

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

Conventional structure and its problems Conventionally, as a flat cathode ray tube, JP-A-57-133778
No. 2 is 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 coating an oxide cathode material on the surface of, for example, a 10-20 μm tungsten wire. In order to extract the beam from this cathode 2 toward the beam extraction electrode 3, the back electrode 1
is lower than the potential of the cathode 2, and the beam extraction electrode 3 is set higher than the potential 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 arranged in the middle of each of the apertures 3' of the beam extraction electrode 3, and a plurality of vertical focusing/deflecting electrodes 4 are arranged in the middle of each of the apertures 3' of the beam extraction electrode 3.
At the same time, a vertical deflection voltage is applied between the facing vertical focusing/deflection 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 15
When all book cathodes 2 are activated, the electron beam is deflected to draw 240 horizontal lines on the screen.

Next, the control electrodes 6 are composed of conductive plates 62 each having a vertically long slit 61, and a plurality of control electrodes 62 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, 320 picture elements can be displayed per horizontal 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 composed 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 to Each elemental electron beam is deflected in the horizontal direction, and 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 installed horizontally at the same position as the vertical focusing/deflecting electrode 4, and has the effect of accelerating the electron beam and expanding the vertical deflection at the same time. .

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 phosphor 20 is 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. The horizontal broken lines drawn on the screen 11 in FIG. Indicates the horizontal division displayed.

The flat cathode ray tube with the configuration described above uses multiple line cathodes and multiple control electrodes to deflect the electron beam vertically and horizontally for each block, forming one overall image on the screen. It is something that is synthesized.

However, when combining multiple images on the screen to create one overall image, the brightness of each block,
Furthermore, uniformity of the spacing between horizontal lines (scanning lines) is strictly required, and stability of the driving circuit is also required.

OBJECTS OF THE INVENTION In view of the above drawbacks, the present invention provides a flat cathode ray tube that can stabilize the vertical deflection amplitude during image synthesis in the flat cathode ray tube.

Structure of the Invention In order to achieve the above object, the flat cathode ray tube of the present invention extends at least one of the plurality of electrodes arranged after vertically deflecting an electron beam horizontally to the outside of the effective screen. At least one electrode outside the effective screen is shaped so that the electron beam transmittance changes in the vertical direction, and the vertical amplitude of each cathode is determined by this beam transmittance.
and a beam position, and is configured to control a vertical deflection circuit based on this detection signal.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 2 shows one embodiment of the electrode configuration from the back electrode 1 to the beam position detection electrode. Components corresponding to those in FIG. 1 are given the same reference numerals. In this embodiment, a beam position detection electrode 1 is placed outside the horizontal effective screen of the first shield electrode 5 and the electron beam flow control electrode 6.
6 and 17 are provided. Therefore, other electrodes 1~
4 also has a structure that extends outside the horizontal effective screen. The first beam position detection electrode 16 is separated from the electrode 5 and has a wedge-shaped opening 16' extending over the vertical scanning area of each cathode. Furthermore, the second beam position detection electrode 17 is separated from the electron beam flow control electrode 6 within the effective screen, and is arranged in correspondence with the first beam current detection electrode 16.

Next, a method for stabilizing the vertical scanning amplitude and the position where the beam reaches the screen will be described.

FIG. 3 is a vertical cross section of the configuration shown in FIG. 1, and the trajectory of the electron beam 25 shown here is
This is an example of operation in which the voltage of the video signal applied to the electron beam flow control electrode 6 is lowered. Here, it is assumed that the electron beam 25 from each cathode is deflected in 16 steps in the vertical direction (arrow V), and the entire screen is constructed by keeping the scanning line interval constant.

At this time, the joint between the vertical scanning areas of each cathode 2, that is, the position V1-16 on the screen of the electron beam 25 in FIG. 3 and the electron beam 25'
It is necessary that the interval between the position V2-1 and the position V2-1 where the cathode arrives on the screen is approximately equal to the vertical scanning interval for each cathode. For this purpose, as shown in FIGS. 2 and 4, an opening 16' is provided in the first beam position detection electrode 16 provided outside the effective screen of the first shield electrode 5.
The screen arrival position of the beam is determined by detecting the amount of beam flowing into this electrode 16 and the amount of beam passing through the aperture 16' and flowing into the second beam position detection electrode 17 provided outside the effective screen of the control electrode 6. and control the beam so that it reaches the correct location.

FIG. 5 shows an example of this. First, at the stage where the electron beam is adjusted to be incident on the correct position on the screen as an initial adjustment, the first beam position detection electrode 16 and the second beam position detection electrode 17 are
The beam current flowing into the detector 6 is detected for each horizontal scan.
1 and 62, and input this to the comparator 63. The comparator 63 calculates the difference or ratio between the respective incoming beam current values, and inputs this into the memory circuit 65 by turning the switch 64 to the a side.

As described above, the first beam current detection electrode 16 is provided with the wedge-shaped aperture 16', so that when the beam is deflected in the vertical direction, the beam position detection electrode 16 and Since the beam currents flowing into the beams 17 are different, the difference or ratio between the two can be correlated with the position where the beam reaches the screen.

When the above input operations are completed, the written information is read out from the memory circuit 65 in synchronization with vertical and horizontal scanning. On the other hand, then the first and second
The beam current flowing into the beam position detection electrodes 16 and 17 is constantly detected and compared, and the switch 64
By moving to the b side, the output from the comparator 63 and the output read from the memory circuit 65 are compared by the comparator 66, and when a difference occurs between the two, the difference signal is input to the vertical deflection control circuit 67. , the voltage applied to the vertical focusing/deflection electrode 4 is controlled so as to correct the electron beam position.

FIG. 6 shows another embodiment for controlling the electron beam position. When the beam current incident on the first shield electrode 5 is controlled to a constant value, the current can be detected from both the first beam position detection electrode 16 and the second beam position detection electrode 17 described in the embodiment of FIG. It is no longer necessary to do this, and it is possible to correlate only the value of the beam current flowing into any one electrode with the position of the beam arriving on the screen. Therefore, in this embodiment, the first beam position detection electrode 1
6 or the second beam position detection electrode 17 by the detector 71, and as in the embodiment shown in FIG. Enter. After that, turn the switch 72 to the b side, and the detector 7
A comparator 74 compares the output of 1 and the signal read from the memory circuit 73, and the vertical deflection control circuit 75 is controlled by the output.

As explained above in the embodiments of FIGS. 5 and 6, by correlating the current value flowing into the beam current detection electrode placed after the vertical deflection electrode with the beam position reaching the screen, it is possible to always This allows the beam to reach the correct location.

In the above embodiment, the beam position detection electrode was provided at the position of the first shield electrode and the control electrode, but
It goes without saying that any electrode after vertical deflection may be used.

Effects of the Invention In summary, the present invention provides at least one outside of the effective screen of a plurality of electrodes arranged on the screen side of the vertical deflection electrode, which is electrically separated from the inside of the effective screen, and whose beam transmittance is reduced in the vertical direction. Equipped with electron beam position detection electrodes of different shapes, the beam position is controlled by constantly comparing the beam current when the beam reaches the correct position on the screen with the subsequent beam inflow current value. This has the advantage that the position on the screen to be reached can be accurately maintained and the vertical deflection amplitude can be stabilized.

[Brief explanation of drawings]

FIG. 1 is an internal perspective view showing the basic configuration of a conventional flat cathode ray tube, FIG. 2 is a perspective view showing the main electrode configuration of a flat cathode ray tube according to the present invention, and FIG. 3 is a flat cathode ray tube according to the present invention. FIG. 4 is a vertical sectional view of an embodiment of the tube, FIG. 4 is a perspective view of the first and second beam position detection electrodes in an embodiment of the flat cathode ray tube according to the present invention, and FIGS. 5 and 6 are respectively according to the present invention. FIG. 2 is a beam position control circuit diagram in a flat cathode ray tube. 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, 1
6...First beam position detection electrode, 17...Second beam position detection electrode, 31, 61, 62, 71...
Beam current detector, 63, 66, 74... Comparator, 65, 73... Memory circuit, 67, 75...
...Vertical deflection control circuit.

Claims (1)

[Scope of Claims] 1. A linear cathode, a back electrode and a beam extraction electrode arranged on both sides of the linear cathode, a vertical deflection electrode that vertically deflects an electron beam extracted from the beam extraction electrode, and a plurality of electrodes arranged on the screen side of the vertical deflection electrode, at least one of the plurality of electrodes is electrically separated from the inside of the effective screen and has a beam transmittance different from the outside of the effective screen in the vertical direction; A flat cathode ray tube characterized by having an electron beam position detection electrode having a shape. 2 The signal from the electron beam position detection electrode when the electron beam is incident on the correct position on the screen is stored in a memory circuit, and then the signal from the electron beam position detection electrode and the signal from the electron beam position detection electrode are input into the memory circuit during actual operation. 2. A flat cathode ray tube according to claim 1, wherein the amount of vertical deflection is controlled by comparing the signals so that the electron beam is always incident on the correct position on the screen.