JPS6154141A - Display device - Google Patents

Abstract

PURPOSE:To improve an electron beam control function by dividing a rear electrode into two or more element electrodes that are parallel to a linear cathode, making the two of more element electrodes correspond to each linear cathode, and applying different pulse voltage to the respective element electrodes CONSTITUTION:A picture display device is formed by sequentially providing a rear electrode 1, linear cathode 2, vertical focusing electrodes 3 and 3', vertical deflection electrode 4, control electrode 5, horizontal focusing electrode 6, horizontal focusing electrode 6, horizontal deflection electrode 7, acceleration electrode 8, and screen 9. In this case, the rear electrode 1 is provided into three element electrode groups 37a to d, 38a to d, and 39a to d corresponding to the linear cathode 2 in the same way as an electrode 36 and pulse voltage can independently be applied to the respective element electrodes synchronizing to vertical deflection pulses. As a result, an electron beam can fully be focused by forming an electron lens system around the linear cathode 1 and picture quality can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a display device using an electron source having a linear cathode.

Conventional Structure and Its Problems FIG. 1 shows the basic structure of an image display device proposed in Japanese Patent Application Laid-Open No. 57-208046.

This display device consists of, in order from the back to the front, a back electrode 1, a line cathode 2 as a beam source, a vertical focusing electrode 3.3'
, a vertical deflection electrode 4, a beam flow control electrode 6, a horizontal focusing electrode 6, a horizontal deflection electrode 7, a beam acceleration electrode 8, and a screen plate 9 are arranged; 11. These are housed in the evacuated interior of a flat glass bulb (not shown). Electrode 3, 3'
Correspondingly, the electron beam control means includes a beam flow control electrode 5. The electron beam deflection means is a vertical deflection electrode 4. They respectively correspond to the horizontal deflection electrodes 7, and the light emitting means correspond to the screen plate 9.

A line cathode 2 serving as a beam source is stretched horizontally so as to generate an electron beam distributed linearly in the horizontal direction, and a plurality of line cathodes 2 (here, (Only four wires, 2i to 22 are shown) are provided. In this example, it is assumed that 16 are provided.

Let's say 2i~2yo. These line cathodes 2 are, for example, 10~
It consists of an oxide cathode material coated on the surface of a 2oμΦ tungsten wire. Then, as will be described later, the electron beams are controlled to be emitted sequentially from the upper line cathode 2a for a fixed period of time. (The back electrode 1 suppresses the generation of electron beams from other line cathodes 2 other than the line cathode 2 that is controlled to emit electron beams for a certain period of time, and directs the generated electron beams only in the forward direction. ) This back electrode 1 is attached to the inner surface of the rear wall of the glass bulb 2! It may be formed by a coating film of ''h'll1-CJ material.

The vertical focusing electrode 3 is a conductive plate 11 having a horizontally long slit 10 facing each of the line cathodes 2a to 2yo, and extracts the electron beam emitted from the line cathode 2 through the slit 10, and vertically Focus in the direction of force.

(The slit 1o may be provided with crosspieces at appropriate intervals in the middle, or may be a row of through holes provided in a large number at small intervals in the horizontal direction (intervals that are almost touching). (It may be configured substantially as a slit.)
A plurality of direct deflection '1tL poles 4 are arranged horizontally at intermediate positions of the slits 1o, and conductors 13,
13'. Then, a vertical deflection voltage is applied between the opposing conductors 13 and 13' to deflect the electron beam in the vertical direction. In this example, the electron beam from one line cathode 2 is vertically deflected to positions corresponding to 16 lines by a pair of conductors 13° and 13'. And 16ffI! 15 corresponding to each of the 15 line cathodes 2 by the vertical deflection electrode 4 of iI
A pair of electric bodies is constructed, and in the end, 240
The electron beam is deflected to draw a horizontal line on the book.

Next, the control electrodes 5 are composed of conductive plates 15 each having a vertically long slit 14, and a plurality of control electrodes 15 are arranged in parallel in the horizontal direction at predetermined intervals. In this embodiment, 320 conductive plates 15a to 1'5n for control electrodes are provided (only 1° is shown in the figure). (The control electrodes 6 each direct the electron beam 1 time in the horizontal direction.)
It is divided into picture elements and taken out, and the amount of passage thereof is controlled in accordance with the video signal for displaying each picture element. ) Therefore, if 32,020 control electrodes 6 are provided, 320 picture elements can be displayed per one horizontal line.

In addition, in order to display images in color, each picture element is R, G.
, B, and each control electrode 6 has its R
, G, and B video signals are sequentially added. Also, 320
320 sets of video signals for one line are simultaneously applied to the control electrode 5 of the book, and the video for one line is displayed at one time.

The horizontal focusing electrode 6 is composed of a conductive plate 17 having a plurality of 320 long slits 16 in the vertical direction facing the slits 14 of the control electrode 6, and focuses the electron beam for each pixel divided in the horizontal direction. Each is focused horizontally into a narrow electron beam.

The horizontal deflection electrode 7 includes a plurality of conductors 1 [L plate 18
A horizontal deflection voltage is applied between each of them to deflect the electron beam of each picture element in the horizontal direction, and sequentially illuminate each of the R, G, and B phosphors on the screen 9. Illuminate it to make it emit light. In this example, the deflection range is the width of one pixel for each electron beam. The accelerating electrode 8 is composed of a plurality of conductive plates 19 provided horizontally at the same position as the vertical deflection electrode 4. has been
The electron beam is accelerated to collide with the screen 9 with sufficient energy.

The screen 9 is constructed by applying a phosphor 2o that emits light when irradiated with an electron beam to the back surface of a glass plate 21, and adding a metal back layer (not shown).

The phosphors 2o are provided with one pair of phosphors of three colors, R2O and H, for each slit 14 of the control electrode 6, that is, for each horizontally divided electron beam. It is coated vertically in stripes.

In FIG. 1, the broken lines drawn on the screen 9 indicate divisions in the vertical direction that are displayed 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. As shown in an enlarged view in FIG. 2, one section partitioned by these two has R, G, and B phosphors 20 for one picture element in the horizontal direction.
It has a width of 16 lines in the vertical direction.

The size of one section is, for example, 1 size in the horizontal direction and 1 e size in the vertical direction.

Note that in FIG. 1, the length in the horizontal direction is greatly enlarged relative to the length in the vertical direction for clarity.

Further, in this example, one control electrode 6, that is, one 'l
Although only one pair of R, G, and H phosphors 2° is provided for one picture element with respect to the sheet beam, it is of course possible to provide two or more pairs for two or more picture elements; In this case, R, Ci, and B video signals for two or more picture elements are sequentially applied to the control electrode 5, and horizontal deflection is performed in synchronization with the R, Ci, and B video signals for two or more picture elements.

Next, the basic configuration of a drive circuit for displaying television images on this display device will be explained with reference to FIG. First, a driving portion for irradiating the screen 9 with an electron beam to emit raster light will be described.

The power supply circuit 22 is a circuit for applying a predetermined bias voltage (operating voltage) to each electrode of the display device.
A DC voltage of 16 is applied to the horizontal focusing electrode 6, a DC voltage of V2 is applied to the accelerating electrode 8, and a DC voltage of V9 is applied to the screen 9.

Next, a composite video signal of a television signal is applied to the input terminal 23, and a vertical synchronization signal "IJv" is applied to the synchronization separation circuit 24.
and the horizontal synchronizing signal H are separated and extracted.

The vertical drive pulse generation circuit 26 is composed of a counter that is reset by a vertical pulse and counts horizontal pulses, and has an effective vertical scanning period (here, a period of 240H) excluding the vertical retrace period of the vertical period. 15 drive pulses 242 each of length 16H-periods in sequence.
Mouth...produces yo. This drive pulse has 242 ports.
. . . is applied to the line cathode drive circuit 26, where it is inverted so that the line cathode drive pulse voltage is brought to a low potential only during each pulse period and to a high potential of approximately 20 volts during the rest of the pulse period. It is converted to 1ku'...Yo',
Each line cathode 2a.

20,...is added to 2yo. Each M cathode 2
...2 yo is heated by flowing current between the high potential of the drive pulse I' and yo', and the drive pulse I' is heated.
The heated state is maintained so that electrons can be emitted even during the low potential period of ~Y'. As a result, 16 line cathodes 2-2
From y to y, low potential drive pulses ′ to y′ are applied respectively.
Electrons are emitted only during the 16H period when . (During the period when a high potential is applied, the potential at the line cathode 2 is lower than the potential at the position of the line cathode 2 determined by the bias voltage applied to the back electrode 1 and the vertical focusing electrode 3.
Since the high potential applied to y becomes positive, no electrons are emitted from the line cathodes 2a to 2a. Thus,
In the line cathode 2, during the effective vertical scanning period, electrons are sequentially emitted from the upper line cathode 2a toward the lower line cathode 2y every 16H period. The emitted JL electrons are pushed forward by the back electrode 1, pass through the opposing slits 1Q of the vertical focusing electrode 3, and are focused in the vertical direction to form a flat electron beam.

Next, the vertical deflection drive circuit 27 is composed of a counter that is reset by each of the vertical motion pulses I to Y and counts the horizontal synchronizing signal, a conversion circuit that converts the count output to D/8, etc. A pair of vertical deflection signals v and v' which change in 16 steps by 1H during the 16H period of the vertical drive pulses I to Y are generated. Both vertical deflection signals V and V' have a center voltage of v4, and V
V' increases sequentially and V' decreases sequentially, so that they change in opposite directions. These vertical deflection signals V and V' are applied to electrodes 13 and 1 of the vertical deflection electrode 4, respectively.
3', so that each cathode 2-2
The electron beam generated from Y is vertically deflected in 16 steps, and as mentioned earlier, on the screen 9, one electron beam scans 16 lines of raster one by one from the top.
It is deflected to draw line by line.

As a result of the above, an electron beam is emitted from the top of the 16 line cathodes 2I to 2Y in order for each faH period, and each electron beam is sequentially emitted for one line from the top to the bottom within 16 sections in the vertical direction. By being deflected one by one, the electron beam is vertically deflected one line at a time on the screen 9 from the first line at the upper end to the second ao line at the lower end, and a total of 240 raster lines are drawn.

The electron beam thus vertically deflected is divided into 320 sections in the horizontal direction by the control electrode 5 and the horizontal focusing electrodes 6 and K, and then extracted. Figure 1 shows one of these categories. This electron beam r, I? For each 'r section, the amount of electrons passed is controlled by the control electrode 5, focused horizontally by the horizontal focusing electrode 6 into one thin electron beam, and deflected horizontally in three stages by the horizontal deflection means described below. The R, G, and B phosphors 20 on the screen 9 are sequentially irradiated with the light.

That is, the horizontal drive pulse generation circuit 28 is composed of three vertically connected monostable multi-pipe rake circuits, etc., and is triggered by a horizontal synchronization signal to generate three horizontal drive pulses with equal pulse widths within one horizontal period. Generate r, q, b. Here, as an example, each pulse width is about 17 μsec, and the rightward horizontal scanning period is 50 μsec.
Three pulses r 1 , g 2 , and b are generated during sec. These horizontal drive pulses r+q and b are applied to the horizontal deflection drive circuit 29. This horizontal deflection drive circuit 29 is switched by the horizontal drive pulses r+cr and b to generate a pair of horizontal deflection signals ri and h' which change in three stages. Horizontal deflection signal.

Both h' have a center voltage of v7, and change in opposite directions such that h sequentially increases and h' sequentially decreases. These horizontal deflection signals h 1 and h/ are respectively applied to electrodes 18 and 18' of horizontal deflection electrode A. As a result, each horizontally segmented electron beam is applied to the R, G of the screen 9 during each horizontal period.

It is horizontally deflected so that the phosphor B is sequentially irradiated with 17 μgeC. However, in the display element of FIG. 1, in the horizontal deflection electrode 7, one conductor 16 or 18' is used for deflecting the electron beams of two adjacent sections. Since the electron beams are deflected in opposite directions, the electron beams in 320 sections are divided into odd-numbered sections R- and G-.
, B, then those in even-numbered sections are deflected in the order of B-, G-H, and so on.
Every segment is deflected in the opposite direction.

Thus, in each line raster, the horizontal 3
For each of the 20 sections, the electron beam is connected to each R and GB phosphor 2.
0 is sequentially irradiated.

Therefore, for each horizontal section of each line, the electron beams are
, B, a color television image can be displayed on the screen 9.

Next, the electron beam modulation control part of VC1 will be explained.

1. The signal applied to the television signal input terminal 23 (
The one-image signal is applied to the color demodulation circuit 3Q, where the R
-Y and B-Y color difference signals are demodulated, G-Y color difference signals are matrix-synthesized, and further, they are combined with the luminance signal Y, each of the R, G, and B primary color signals (hereinafter referred to as R, G.
(referred to as B video signal) is output. Those R,G,
B Each video signal is processed by 320 sample and hold circuit sets 31
Added to a-3In. Each sample hold circuit group 3
1&~31n each have three sample and hold circuits for R, G, and B. The sample and hold outputs of these sample and hold circuit sets 31a to 31n are applied to holding memory sets 32a to 32n, respectively.

On the other hand, the sampling reference clock oscillator 33 is a PLL.
(phase-locked loop) circuit, etc., and generates a reference clock of approximately 6.4 MHz in this embodiment. The reference clock is controlled to always have a constant phase with respect to the horizontal synchronizing signal H. This reference clock is applied to the sampling pulse generation circuit 34, where it is delayed by one clock period by a shift register, etc., so that the reference clock is 320 times
sampling pulses a-n are generated in sequence, followed by one transfer pulse. This sampling pulse B-fi corresponds to each picture element when one line of the video to be displayed is divided horizontally into 320 picture elements, and its position is always constant with respect to the horizontal synchronizing signal H. controlled by.

These 320 sampling pulses a-n correspond to the 320 sample-and-hold circuit sets 31a to 31n, respectively.
is added to each sample-and-hold circuit set 3.
In 1a to 31n, R, G, and B video signals of each picture element when one line is divided into 320 picture elements are individually sampled and held. The sample-held 320 sets of R, G, and B video signals are transferred to the memory 3 after completing the sample hold for one line.
The signals are transferred all at once to 2a and 32c by a transfer pulse t, and held here for the next one horizontal period.

1 line (,
The G and B video signals are applied to 320 switching circuits 36a to 35n, respectively. The switching circuits 35a to 35n are R and G, respectively.

Each switching circuit 35a has individual input terminals of B and a common output terminal that sequentially switches and outputs them.
The output of ~35H is used as a control signal for modulating the electron beam and is used as a control electrode of the display device 50320 conductive plates 15=
1 to 16n, respectively. Each switching circuit 35a to 35n is a switching pulse generation circuit 3.
Switching is simultaneously controlled by switching pulses applied from 6 to 6. The switching pulse generation circuit 36 receives signals r, g,
The approximately 50 μl IeG in the center of each horizontal period is divided into three parts, and the switching circuits 35a to 35n are switched by approximately 17 μSeC, and the R, G, and H video signals are time-divided and output alternately and sequentially. and control electrode 156
A switching signal r+q+b is generated so as to be supplied to 15n. However, among the switching circuits 35a to 35H, odd-numbered switching circuits 35a, 35C...
... are switched in the order of RG-, B, and the even-numbered switching circuits 3sb, 3sd...35n
On the contrary, the signals are switched in the order of BGH.

What should be noted here is that the switching circuits 35a to 3
Switching the supply of Rj G I B video signals at 5n, and R, G, and R of electron beams by the horizontal deflection drive circuit 29.
The horizontal deflection for switching the irradiation to the phosphor B is synchronously controlled so that it completely matches both the timing and the order. As a result, when the electron beam is irradiating the R phosphor, the irradiation amount of the electron beam is controlled by the R video signal, and G and B are similarly controlled, so that the R, G, and B of each picture element are controlled in the same manner. The light emission of each phosphor is controlled by the R, G, and B video signals of that picture element, and each picture element is displayed by emitting light according to the input video signal. Such control is performed simultaneously on 320 picture elements for one line to display one line of video, and then sequentially performed for 240 lines starting from the upper line, so that one video is displayed on screen 9. will be done.

The above operations are performed on one input television signal.
This is repeated for each field, and as a result, a moving television image is projected on the screen 9'' in the same way as in a normal television receiver.

The display device described above has the following problems.

The device 11 has only one back electrode for multiple wire cathodes, and one back electrode for one wire cathode.
Even if the IL poles are made to correspond, the electron lens system around the line cathode has a porantial distribution P&:J as shown in Figure 4.
The problem is that the device beam E formed from the line cathode 1 has poor convergence.

Therefore, the amount of electron beam passing through the slit 10 is small, 10 to 100μ8/N, which is not only bad for the utilization of the electron beam emitted from the line cathode 1, but also unnecessary since the electron beam hits the focusing electrode 3. A current flows through the electrode, causing a voltage change.9 Gas is generated from the electrode due to the collision with the electron beam, poisoning the cathode or heating the electrode, impairing assembly position accuracy. In addition, in this apparatus, if the positional accuracy of the line cathode 1 and the line cathode 10 is even slightly poor, the trajectory of the electron beam will be deviated, and the image quality will be significantly adversely affected. for example,
The positioning accuracy of this device is said to be less than ±10 μm, but if the line cathode deviates by +20 μm, the beam landing position and focus diameter will be affected.

This affects the amount of beam isotropically, causing a decrease in color purity, a decrease in brightness, etc., and worsening the uniformity of image quality. However, there was a problem in that there was no means to correct this.

Furthermore, when the electron beam is deflected in the vertical direction, deflection aberration occurs, and at the joint on the screen plate 9, which is the display surface,
By the amount of aberration, as shown in FIG.
There was a problem in that since the tails were drawn and overlapped, the claw-like portions appeared as seams on the display screen.

OBJECTS OF THE INVENTION An object of the present invention is to provide a display device with good image quality by enhancing the electron beam control function near the linear cathode.

Structure of the Invention The back electrode K is provided with an electron source including electron beam extraction electrodes facing substantially parallel to each other and a plurality of line cathodes disposed between them, and deflects the electron beam extracted from the electron source. In a display device that accelerates the phosphor to emit light, the back electrode is divided into a plurality of element electrodes parallel to the linear cathode, and the plurality of element electrodes correspond to the outer linear cathode. By applying different pulse voltages to each of the plurality of element electrodes, the convergence of the electron beats is improved.

Description of Actual HM Example The main part of the first embodiment of the present invention is shown in FIG. The figure shows the vicinity of the line cathode, and compared to the conventional example in Figure 1,
The structure of the back electrode 37 is different.

That is, the back electrode 36 is divided into three element electrode groups, 3F-2, 38I-2, and 39I-2, corresponding to the line cathodes 2. A pulse voltage can be independently applied to each back electrode in synchronization with the vertical deflection pulse. The distance between the back electrode 36 and the line cathode 20 is 2 aw, the distance between the line cathode 2 and the vertical focusing electrode 3 is 3 aw, the width of the slit 1o is 0.5all, and the line cathodes 2 are stretched at an interval of 1Qa+. The back electrode 36 is composed of three electrodes with a width of 3 mm and is configured to act as a back electrode for one line cathode 2.The vertical focusing electrode 3 has a constant voltage of 30 cm, and the line cathode 2
A pulse voltage of -30V is applied to. Back electrode 37
-60V111 [pole 3s, a91ci-y.

~-5oV is applied. As a result, the button as shown in Figure 7,
The potential distribution P becomes deeper between the line cathodes 2, the lens action of the electron lens becomes stronger, and the electron beam is sufficiently focused. Therefore, the amount of electron beam passing through the slit 1o increases, and the amount of electron beam hitting the vertical focusing electrode 3 decreases, resulting in high brightness and good image quality.
The gas generated from the electrode is also reduced, and the cathode is less poisoned. will also become smaller.

In the second embodiment shown in FIG. 8, the structure of the back electrode is similar to that of the first embodiment, but the voltage applied to the back electrodes 38 and 39 is changed in synchronization with the vertical deflection pulse voltage. . That is, when the electron beam emitted from the line cathode 2a takes the electron beam trajectory 40, the voltage applied to the back electrode 3a is -60V.
, -70V to 39a, -70V to back electrode 38a.
A voltage of 80V is applied depending on the degree of deflection. In addition, when the electron beam trajectory 41 is set in the beam emitted from the line cathode 20, on the contrary, -yoV is applied to the back electrodes 380 and 370, respectively.
, a constant voltage of -eoV is applied to the back electrode 390 from -70V to
A voltage of -aoV is applied depending on the degree of deflection. In other words,
The voltage applied to the back electrode on the side opposite to the direction of deflection is increased. As a result, the electron beam emitted from a position offset from the central axis of the line cathode, which was the cause of deflection aberration and tailing, is cut, and the tailing of the electron beam spot is eliminated and displayed. Seams on surfaces become invisible.

Also, in this example, the back electrode is divided into three parts, but even if it is divided into two parts, it is divided into four parts.
The idea of the invention is the same even if the number of divisions is greater than that, and the greater the number of divisions, the better the effect will be.

Furthermore, even if the position of the line cathode shifts in the vertical direction during assembly, it can be compensated for by adjusting the voltage applied to each back electrode to create a vertically asymmetric potential distribution.

Effects of the Invention In the display device of the present invention, the back electrode is divided into electrode groups parallel to the line cathode, a plurality of back electrodes are made to correspond to one line cathode, and an electron lens system around the line cathode is constructed. This configuration improves the focusing ability of the electron beam and improves the image quality.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the basic configuration of a conventional display device, FIG. 2 is an enlarged plan view of the main parts of the screen, and FIG. 3 is a block diagram showing the basic configuration of the drive circuit of the device. Figure 4 shows the state near the cathode of the device.
Fig. 5 is a schematic cross-sectional view of the same device at 1:1 to reduce the vertical deflection characteristics, Fig. 6 is a B, 'l 1M diagram of the main part of this embodiment, and Fig. 7 is a vicinity of the cathode of this embodiment. FIG. 8 is a schematic sectional view showing the vertical deflection characteristics of this embodiment. 2...Line cathode, 3,3'...Electron beam extraction electrode, 1Q...Slit, 36...
Back electrode, 3-372, 38-382, 39-
392... Wave, (゛, Name of electrode/proxy taper Patent attorney Toshio Nakao and 1 other person' Figure 2 Figure 31A Figure 4 and Figure 5': iJ 6 Figure 7 Figure 8A

Claims (3)

[Claims] (1) An electron source including a back electrode, an electron beam extraction electrode facing substantially parallel to the back electrode, and a plurality of linear cathodes arranged between the back electrode, and an electron beam emitted from the electron source. In a display device that deflects and accelerates a phosphor provided on a display surface to emit light, the back electrode is divided into a plurality of element electrode groups parallel to the linear cathode, and a plurality of A display device characterized in that each of the element electrodes of a book is configured to correspond to each other, and different voltages are applied to each of the element electrodes. (2) Deflection means for deflecting the electron beam in a direction perpendicular to each linear cathode is provided, and a pulse voltage synchronized with the deflection pulse that drives the deflection means is applied to each element electrode constituting the back electrode. 2. The display device according to claim 1, wherein the display device applies: (3) The display device according to claim 1, wherein a voltage corresponding to the positional shift of the line cathode is applied to each element electrode constituting the back electrode.