JPH0416894B2 - - 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 the surface of a tungsten wire with a diameter of 10 to 20 μm with an oxide cathode material. 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 way passes through the aperture 3' of the beam extraction electrode 3 and is vertically focused.
Proceed to the area of the deflection electrodes 4. Vertical focusing/deflection electrode 4
are arranged in the middle of each of the apertures 3' of the beam extraction electrode 3, and at the same time focus the electron beam in the vertical direction with an electrostatic lens formed between the first shield electrode 5 and the next first shield electrode 5. A vertical deflection voltage is applied between the vertical focusing/deflecting electrodes 4 facing each other 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. 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 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. In other words, if the parallel state of each line of the raster deviates, the voltage distribution in the conductor of the vertical deflection electrode is adjusted for each section in the vertical direction to correctly display each line in the predetermined parallel state position. It is something that can be done.

However, when combining multiple images on the screen to create one overall image, the brightness of each block,
Although uniformity of the spacing between horizontal lines (scanning lines) is strictly required, no concrete means have been shown for detecting whether the parallel state of each line is deviated. Since stability of the drive circuit is also required, there is a problem in that manufacturing is difficult.

Purpose of the Invention In view of the above drawbacks, the present invention provides a flat cathode ray tube that is capable of achieving uniformity of brightness for each cathode and stability of vertical deflection amplitude during image synthesis in the flat cathode ray tube. It is something to do.

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. The beam current is detected from at least one electrode outside the effective screen, and is fed back to the drive circuit of the back electrode or beam extraction electrode, and the beam current is detected from at least one electrode outside the effective screen. An electrode for detecting the position of the electron beam reaching the screen is disposed on at least one of the electrodes, and the electrode is configured to detect the vertical amplitude and beam position of each cathode.

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 current detection electrode. Components corresponding to those in FIG. 1 are given the same reference numerals. In this embodiment, a beam current detection electrode 1 is placed outside the horizontal effective screen of the first shield electrode 5 and the electron beam flow control electrode 6.
5, 16, and 17 are provided. Therefore, the other electrodes 1 to 4 also extend outside the horizontal effective screen. The first beam current detection electrode 15 may or may not have a slit or round aperture, and if it has an aperture, it is an aperture of a certain size, and the electrode 5 within the effective screen is Separated. The second beam current detection electrode 16 is also separated from the electrode 5 and has a wedge-shaped aperture 1 extending over the vertical scanning area of each cathode.
6' is provided. Furthermore, the third beam current detection electrodes 17-2 and 17-1 are separated from the electron beam flow control electrode 6 in the effective screen and are arranged corresponding to the first and second beam current detection electrodes 15 and 16. There is. The first beam current detection electrode 15 and the third beam current detection electrode 17-2 are for making the beam current uniform by detecting the beam current. The beam current detection electrode 17-1 detects the beam position by detecting the beam current.

FIG. 3 shows an embodiment of a control system for uniformizing the beam current for each cathode in a flat cathode ray tube having the above electrode configuration.

The beam that has passed through the beam extraction electrode 3 is focused and deflected by the vertical focusing/deflection electrode 4, and then
The beam enters the current detection electrode 15. Here, a certain DC current that is not modulated by a video signal or the like is made to enter, and this current is detected by the detector 31. The first beam current detection electrode 15 is then compared with a required predetermined current value, and the difference is input to the beam extraction electrode voltage control circuit 32 to control the voltage supplied to the beam extraction electrode 3. The beam current incident on the beam can always be kept at a predetermined constant current value. It goes without saying that if the first beam current detection electrode 15 has a slit or a circular opening, the beam current may be detected by the third beam current detector 17-2. In this case, by providing an aperture of a certain size, the amount of electron beam passing through the aperture is compared with a predetermined current value, and the voltage supplied to the beam extraction electrode 3 is determined based on the difference. By controlling this, it becomes possible to control the beam amount.

By performing the above operations for each image area corresponding to each cathode, an image with uniform brightness can be obtained over the image area corresponding to each cathode.

Next, we will discuss the vertical scanning amplitude and the method for stabilizing the position where the beam reaches the screen.

FIG. 4 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. 4 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 reason, as shown in FIGS. 2 and 5, an opening 16' is provided in the second beam current detection electrode 16 provided outside the effective screen of the first shield electrode 5.
The amount of beam flowing into this electrode 16 and the amount of beam passing through the aperture 16' and flowing into the third beam current detection electrode 17-1 provided outside the effective screen of the control electrode 6 are detected, and the screen arrival position of the beam is detected. judge,
Control the beam so that it reaches the correct location.

FIG. 6 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 second beam current detection electrode 16 and the third beam current detection electrode 17 are adjusted.
-1 is detected by detectors 61 and 62 for each horizontal scan, and is input to a comparator 63. The comparator 63 calculates the difference or ratio of the respective incoming beam current values, and converts this to the switch 6.
4 to side a and input it to the memory circuit 65.

As described above, the second 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 current detection electrode 16 and Since the beam currents flowing into the beams 17-1 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 second and third
By constantly detecting the beam current flowing into the beam current detection electrodes 16 and 17-1 and comparing the two, and by turning the switch 64 to the b side, the output from the comparator 63 and the output read from the memory circuit 65 are compared. When a difference occurs between the two, the difference signal is inputted 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. The procedure for controlling the beam position is summarized as follows.

a Perform initial adjustment so that the beam enters the correct position, and then adjust the second beam current detection electrode 16 and the third beam current detection electrode 17-1 at that time.
Detect the beam current flowing into the beam.

b The second beam current detection electrode 16 in the comparator 63,
The difference or ratio between the values of the beam currents flowing into the third beam current detection electrode 17-1 is determined and input to the memory circuit 65.

c The beam current flowing into the second beam current detection electrode 16 and the third beam current detection electrode 17-1 during normal operation is detected, and the output from the memory circuit 65 is detected by the comparator 66.
Compare with.

d If there is a difference between the two, control the electron beam position using the difference signal.

Therefore, although there is a difference whether the initial value when accurately adjusted is stored as a difference or as a ratio, no inconvenience occurs.

FIG. 7 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 as explained in FIG. 3, the second beam current detection electrode 16 and the third beam current detection electrode described in the embodiment of FIG. It is no longer necessary to detect the current from both electrodes 17-1, and it is possible to correlate only the value of the beam current flowing into one of the electrodes with the position of the beam reaching the screen. Therefore, in this embodiment, the beam current is detected by the detector 71 from either the second beam current detection electrode 16 or the third beam current detection electrode 17-1, and as in the embodiment of FIG. The output of the detector 71 is input to the memory circuit 73 at the stage of initial adjustment. Thereafter, the switch 72 is turned to the b side, the output of the detector 71 and the signal read from the memory circuit 73 are compared by the comparator 74, and the vertical deflection control circuit 75 is controlled by the output.

As explained above in the embodiments of FIGS. 6 and 7, 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 current 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 As explained above, by detecting the value of the beam current flowing into the beam current detection electrode provided outside the effective screen and controlling the voltage of the beam extraction electrode based on this, a constant current can be maintained. In addition to obtaining a uniform brightness image, the beam position is controlled by constantly comparing the beam current when the beam reaches the regular screen position with the subsequent beam inflow current value using the beam position detection electrode. This makes it possible to accurately maintain the position on the screen where the beam reaches.

[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 flat cathode ray tube according to the present invention; FIG.
A perspective view of the third beam current detection electrode, and FIGS. 6 and 7 are diagrams of a beam position control circuit in a flat cathode ray tube according to the present invention, respectively. 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
5...First beam current detection electrode, 16...Second beam current detection electrode, 17...Third beam current 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, an electron beam amount detection electrode arranged outside at least one effective screen of the plurality of electrodes, and at least one effective screen of the plurality of electrodes; A flat cathode ray tube characterized by having electrodes arranged on the outside to detect the position of the electron beam reaching the screen. 2 Electron beam amount detection electrodes are electrically separated within the effective screen and outside the effective screen, and the first electrode through which the beam passes has an aperture of a certain size for the electron beam. A flat cathode ray tube according to claim 1, characterized in that: 3. The flat cathode ray tube according to claim 1, wherein the electron beam amount detection electrodes are electrically separated within the effective screen and outside the effective screen, and the electrodes outside the effective screen are non-porous. 4 The electron beam position detection electrode is electrically separated inside and outside the effective screen, and is further separated from the electron beam amount detection electrode, and the first electrode through which the beam passes has a shape with different beam transmittance in the vertical direction. A flat cathode ray tube according to claim 1, characterized in that the flat cathode ray tube is provided with: