JPH0619953B2 - Display device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device using an electron source.

Configuration of Conventional Example and Problems Thereof The present inventors have previously proposed an image display device (Japanese Patent Laid-Open No. 57-57157).
-208045). First, the basic configuration of this image display device will be described with reference to FIG.

This display device has a back electrode 1, a line cathode 2 as a beam source 2, an electron beam extraction electrode 3, 3 ′, a vertical deflection electrode 4, a beam flow control electrode 5, a horizontal focusing electrode 6, in this order from the rear to the front. A horizontal deflection electrode 7, a beam accelerating electrode 8 and a screen plate 9 are arranged and configured, and these are housed in a vacuumed inside of a flat glass bulb (not shown).

Here, the linear electron source is composed of a back electrode 1 and a linear cathode 2 as a beam source, the electron beam extraction means corresponds to the electron beam extraction electrodes 3 and 3 ', and the electron beam control means controls the beam flow. The electrodes 5 and the electron beam deflecting means correspond to the vertical deflecting electrodes 4 and the horizontal deflecting electrodes 7, respectively, and the light emitting means correspond to the screen plate 9.

A line cathode 2 as a beam source is horizontally stretched so as to generate an electron beam that is linearly distributed in the horizontal direction, and a plurality of such line cathodes 2 are vertically arranged at appropriate intervals (here, (Only four of 2a to 2d are shown). In this embodiment, 15 are provided. 2 a to 2 ta. These wire cathodes 2 are formed by coating an oxide cathode material on the surface of a tungsten wire having a diameter of 10 to 20 μφ, for example. Then, as will be described later, the electron beam is controlled so as to emit an electron beam sequentially from the upper line cathode 2a at regular intervals. (The back electrode 1 suppresses the generation of the electron beam from the other line cathodes 2 other than the line cathode 2 which is controlled to emit the electron beam for a certain period of time, and the generated electron beam is directed only in the forward direction. This back electrode 1 may be formed by a coating film of a conductive material attached to the inner surface of the rear wall of the glass pulp. Further, instead of the back electrode 1 and the line cathode 2, a planar electron beam emitting cathode may be used.

The electron beam extraction electrode 3 is a conductive plate 11 having a horizontally long slit-shaped electron beam passage hole 10 facing each of the line cathodes 2a to 2ta, and the electron beam emitted from the line cathode 2 is converted into an electron beam. It is taken out through the beam passage hole 10 and focused in the vertical direction. (The electron beam passage holes 10 may be provided with crosspieces at appropriate intervals in the middle, or may be a row of through holes provided side by side with a small number of intervals in the horizontal direction (intervals of almost contact). May be configured as a slit). A plurality of vertical deflection electrodes 4 are horizontally arranged at intermediate positions of the electron beam passage holes 10, and conductors 13 and 1 are provided on the upper surface and the lower surface of the insulating substrate 12, respectively.
3'is provided. Then, a vertical deflection voltage is applied between the conductors 13 and 13 ′ facing each other to deflect the electron beam in the vertical direction. In this embodiment, one wire cathode 2 is formed by a pair of conductors 13 and 13 '.
The electron beam from is vertically deflected to the position of 16 lines. Then, by the 16 vertical deflection electrodes 4, 15
Fifteen pairs of electric conductors corresponding to each of the line cathodes 2 are formed, and eventually the electron beam is deflected so as to draw 240 horizontal lines on the screen 9.

Next, each of the control electrodes 5 is composed of a conductive plate 15 having a slit 14 which is long in the vertical direction, and a plurality of the control electrodes 5 are arranged side by side in the horizontal direction at a predetermined interval. In this embodiment, 320 control electrode conductive plates 15a to 15n are provided (only 10 are shown in the figure). (Each of the control electrodes 5 separates and takes out the electron beam in the horizontal direction for each picture element, and controls the passing amount according to a video signal for displaying each picture element.)
Therefore, if 320 control electrodes 5 are provided, 320 picture elements can be displayed per horizontal line. Further, in order to display an image in color, each picture element is to be displayed in a fluorescent body of three colors of R, G, B, and each control electrode 5 has its R,
G and B video signals are sequentially added. Further, 320 sets of video signals for one line are simultaneously applied to 320 control electrodes 5, and one line of video is displayed at one time.

The horizontal focusing electrode 6 is composed of a conductive plate 17 having a plurality of 320 slits 16 which are long in the vertical direction and are opposed to the slits 14 of the control electrode 5, and emit an electron beam for each picture element divided in the horizontal direction. Each is focused horizontally to form a narrow electron beam.

The horizontal deflection electrode 7 is composed of a plurality of conductive plates 18 arranged in the vertical direction at the respective intermediate positions of the slits 16. A horizontal deflection voltage is applied between the horizontal deflection electrodes 7 for each picture element. The electron beams of R, G, and B are deflected in the horizontal direction, and the R, G, and B phosphors are sequentially irradiated on the screen 9 to emit light. The deflection range is the width of one picture element for each electron beam in this embodiment.

The accelerating electrode 8 is composed of a plurality of conductive plates 19 horizontally provided at the same position as the vertical deflection electrode 4.
The electron beam is accelerated so as to strike the screen 9 with sufficient energy.

The screen 9 is configured by applying a fluorescent body 20 which is emitted by irradiation of an electron beam to the back surface of a glass plate 21 and adding a metal back layer (not shown).
The phosphor 20 has a pair of phosphors of three colors R, G, and B for one slit 14 of the control electrode 5, that is, for each electron beam divided in the horizontal direction. They are provided one by one and are applied in stripes in the vertical direction. In FIG. 1, broken lines drawn on the screen 9 indicate vertical divisions corresponding to the plurality of line cathodes 2, and two-dot chain lines correspond to the plurality of control electrodes 5, respectively. Shows the horizontal division. As shown in an enlarged view in FIG. 2, there are R, G, and B phosphors 20 for one picture element in the horizontal direction and one line for 16 lines in the vertical direction. Has a width of. The size of one section is, for example, 1 m in the horizontal direction.
m, 16 mm in the vertical direction.

It should be noted that, in FIG. 1, the length in the horizontal direction is drawn to be much larger than that in the vertical direction for the sake of clarity.

Further, in this embodiment, only one pair of R, G, B phosphors 20 for one picture element is provided for one control electrode 5, that is, one electron beam, but two picture elements or more. Of course, two or more pairs may be provided, and in that case, the R, G, and B video signals for two or more picture elements are sequentially applied to the control electrode 5, and the horizontal deflection is synchronized with them. Done.

Next, a basic configuration of a drive circuit for displaying a television image on this display device will be described with reference to FIG. First, the drive portion for irradiating the screen 9 with the electron beam to cause the raster to emit 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. The back electrode 1 is -V ₁ , the electron beam extraction electrodes 3 and 3'are V ₃ ,
A DC voltage of V ₆ is applied to the V ₃ ′ horizontal focusing electrode 6, V ₈ is applied to the acceleration electrode 8, and V ₉ is applied to the screen 9.

Next, the composite video signal of the television signal is applied to the input terminal 23, and the vertical separation signal V and the horizontal synchronization signal H are separated and extracted by the synchronization separation circuit 24. The vertical drive pulse generation circuit 25 is configured by a counter or the like that is reset by a vertical pulse and counts horizontal pulses, and is an effective vertical scanning period (here, a period of 240H) excluding the vertical blanking period of the vertical cycle. Then, 15 drive pulses a, 16 ...
The drive pulses (a), (b), and (c) are applied to the line cathode drive circuit 26, and are inverted here to have a low potential only during each pulse period, and have a high potential of about 20 V during the other periods, and the line cathode drive is performed. Converted into pulse-a ', ro' ... ta ',
It is added to each wire cathode 2a, 2b ... 2ta. Each wire cathode 2
The drive pulse is heated by the electric current flowing through the high potential of the drive pulse A'-T '.
The heating state is maintained so that electrons can be emitted even in the low potential period. As a result, electrons are emitted from the 15 line cathodes 2a to 2ta only during the 16H period when low-potential drive pulses a'tota 'are applied to each of them. (While the high potential is being applied, the potential applied to the line cathodes 2a to 2t is higher 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 that is applied is positive, the line cathode 2a ~
No electrons are emitted from the 2T. 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 2a for 16H periods. The emitted electrons are pushed forward by the back electrode 1, pass through the opposing slits 10 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 counts the horizontal synchronizing signal that is reset by each of the vertical drive pulse signals, a conversion circuit that performs D / A conversion of the count output, and the like. A pair of vertical deflection signals v and v'changed in 16 steps in steps of 1H are generated during the 16H period of pulse eta. Both of the vertical deflection signals v and v ′ have a center voltage of V ₄ , and are adapted to change in the opposite directions such that v gradually increases and v ′ gradually decreases. These vertical deflection signals v
And v'are applied to the electrodes 13 and 13 'of the vertical deflection electrode 4, respectively, so that the electron beams generated from the respective cathodes 2a to 2b are vertically deflected in 16 steps,
As described above, one electron beam is deflected on the screen 9 so that the raster for 16 lines is sequentially drawn for each one line from the top.

As a result of the above, electron beams are emitted for 16H periods in order from the one above the 15 line cathodes 2a to 2ta, and each electron beam corresponds to one line from the top to the bottom in 15 vertical sections. By sequentially deflecting the electron beam, the electron beam is vertically deflected on the screen 9 one line at a time from the first line at the upper end to the 240th line at the lower end,
A total of 240 lines of raster are drawn.

The electron beam vertically deflected in this way is divided into 320 sections in the horizontal direction by the control electrode 5 and the horizontal focusing electrode 6 and is taken out. FIG. 1 shows one of them. The passing amount of this electron beam is controlled by the control electrode 5 for each section, and is horizontally focused by the horizontal focusing electrode 6 to form one thin electron beam. Each of the R, G, and B phosphors 2 on the screen 9 being deflected to
It is sequentially irradiated with 0.

That is, the horizontal treatment pulse generation circuit 28 is composed of three monostable multivibrators connected in series,
Triggered by the horizontal sync signal, three horizontal drive pulses r, g, b having the same pulse width are generated in one horizontal period. Here, as an example, each pulse width is set to about 17 μsec, and 50 μs which is a moving horizontal scanning period.
Three pulses r, g, and b are generated during ec. The horizontal drive pulses r, g, b are applied to the horizontal deflection drive circuit 29. This horizontal deflection drive circuit 29
Generates a pair of horizontal deflection signals h and h'which are switched by horizontal drive pulses r, g and b and change in three steps. Both of the horizontal deflection signals h and h'have the center voltage of V ₇ , and h gradually increases and h'decreases in the opposite directions. These horizontal deflection signals h,
h'is applied to the electrodes 18 and 18 'of the horizontal deflection electrode 7, respectively. As a result, the electron beams divided in the horizontal direction are horizontally deflected so that the R, G, and B phosphors on the screen 9 are sequentially irradiated for 17 μsec each during each horizontal period. However, in the display element of FIG.
In this case, one conductor 16 or 18 'is used for deflecting the electron beams of two adjacent sections so that the adjacent electron beams may be deflected in opposite directions. Therefore, if the electron beam of the 320th segment is deflected in the order of R → G → B, the electron beams of the even numbered segment are conversely B → G →
For example, the deflection is performed in the order of R, so that the deflection is performed in the opposite direction every other section.

Thus, in each line raster the horizontal 3
An electron beam is sequentially applied to each of the R, G, and B phosphors 20 for each of the 20 sections.

Therefore, for each horizontal division of each line,
A color television image can be displayed on the screen 9 by modulating with the G and B video signals.

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

First, the composite video signal applied to the television signal input terminal 23 is applied to the color demodulation circuit 30, where RY
And BY color-difference signals are demodulated, G-Y color-difference signals are matrix-synthesized, and further, they are synthesized with the luminance signal Y to obtain R, G, B primary color signals (hereinafter, R, G, B video signal) is output. These R, G, B video signals are provided as 320 sets of sample and hold circuit groups 31a-3.
1n added. Each sample hold circuit group 31a-
31n has three sample hold circuits for R, G, and B, respectively. The sample and hold outputs of the sample and hold circuit groups 31a to 31n are added to the holding memory groups 32a to 32n, respectively.

On the other hand, the sampling reference clock oscillator 33 is a PLL
It is composed of a (phase locked loop) circuit and the like, and generates a reference clock of about 6.4 MHz in this embodiment. The reference clock is controlled so as 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,
Here, 320 sampling pulses a to n are sequentially generated during the effective horizontal scanning period (about 50 μsec) of the horizontal period (63.5 μsec) by being delayed by one clock by the shift register. After that, one transfer pulse is generated. These sampling pulses a to n
Corresponds to each picture element when one line of the image to be displayed is divided into 320 picture elements in the horizontal direction, and its position is controlled so as to be always constant with respect to the horizontal synchronizing signal H.

These 320 sampling pulses a to n are the above 320 sets of sample hold circuit groups 31a to 31n, respectively.
To each sample and hold circuit group 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 320 sets of R, G, B video signals sample-held are 320 sets of memory 32a after the sample-hold for one line is completed.
To 32c are transferred all at once by the transfer pulse t, and are held here for the next one horizontal period.

R for one line held in the memories 32a to 32n,
The G and B video signals are applied to 320 switching circuits 35a to 35n, respectively. Switching circuit 35a
.About.35n each have an R, G, B individual input terminal and a common output terminal for sequentially switching and outputting them, and the outputs of the respective switching circuits 35a to 35n serve as control signals for modulating the electron beam. Each of the 320 conductive plates 15a to 15n of the control electrode 5 of the display device is individually added. The switching circuits 35a to 35n are simultaneously switched and controlled by the switching pulse applied from the switching pulse generation circuit 36. The switching pulse generation circuit 36 is controlled by the pulses r, g, b from the horizontal drive pulse generation circuit 28 described above,
Approximately 1 by dividing about 50μsec of the central part of each horizontal period into 3
Switching circuits 35a to 35n are switched every 7 μsec, R, G, and B video signals are time-divisionally and alternately output sequentially, and switching signals r, g, and b are generated so as to be supplied to control electrodes 15a to 15n. . However, switching circuit 3
5a to 35n, the odd-numbered switching circuit 3
.. are switched in the order of R.fwdarw.G.fwdarw.B, and the even-numbered switching circuits 35b, 35d..35n are switched in the order of B.fwdarw.G.fwdarw.R.

Here, it should be noted that the switching circuits 35a-3
The switching of the supply of the R, G, B video signals in 5n and the switching of the irradiation of the electron beams of the R, G, B to the fluorescent body by the horizontal deflection drive circuit 29 and the horizontal deflection are completely performed in terms of timing and order. That is, they are synchronously controlled so that they match. As a result, when the R fluorescent substance is irradiated with the electron beam, the irradiation amount of the electron beam is controlled by the R image signal, and G and B are controlled in the same manner, so that R, G, B of each picture element are controlled. The light emission of each phosphor is controlled by the R, G, and B video signals of the picture element, and each picture element is luminescently displayed according to the input video signal. This control is simultaneously performed for 320 picture elements for one line to display one line of video, and further for 240 lines is sequentially performed from the upper line to display one video on the screen 9. Will be done.

Then, the various operations as described above are performed by the input television signal 1
This is repeated for each field, and as a result, a moving image of a television image is displayed on the screen 9 as in a normal television receiver.

The conventional flat panel image display device as described above has the following problems.

Since the line cathode 2 is sandwiched between the back electrode 1 and the electron beam extraction electrode, the line cathode is confined between wide parallel flat plates having a very small gap. Therefore, the conductance of gas discharge around the linear cathode is poor and the gas is likely to be filled, and the degree of vacuum around the linear cathode 2 is significantly deteriorated. In addition, the gas that comes out naturally from the electrode itself, the gas that comes out when the electron beam hits the electrode, and the cathode line 2 that is coated with carbonate ((Ba, Ca, Sr) CO ₃ ) on the W line When used, a large amount of gas is generated particularly around the linear cathode 2 such as a gas such as CO ₂ which is emitted at the time of activation. Therefore, the electron beam emission characteristics, stability, and life of the cathode are greatly affected by the degree of vacuum around the cathode. Therefore, the conventional configuration uses the linear cathode 2 in the space charge limited region. The electron beam emission characteristics are deteriorated and the electron beam emission characteristics are deteriorated, so that the operating characteristics of the wire cathode enter the temperature limit region in a short time.

Therefore, when the operating characteristics of the wire cathode fall within the temperature-limited region, the electron beam emission characteristics are determined by the temperature of the wire cathode, so that a sufficient stable electron beam emission amount cannot be obtained, leading to a decrease in brightness. Furthermore, the same phenomenon does not occur in all the line cathodes at the same time, and the poisoning differs from place to place.

That is, the generated time also differs depending on the location within one line cathode, and needless to say, the line cathodes also differ from each other, which not only lowers the luminance but also impairs the uniformity of the image quality, which shortens the life of the display device. It was

An object of the present invention is to provide a display device which prevents poisoning of an electron source due to filling of a gas generated in the vicinity of the electron source, has high brightness, has good uniformity of image quality, and has a long life.

Configuration of the invention, the display device of the present invention, a plurality of stretched linear hot cathode,
An electron beam extractor having a back body arranged behind the linear hot cathode and a plurality of electron beam passage holes arranged in front of the linear hot cathode and through which electron beams generated from the linear hot cathode pass. An electrode and a light emitting means that emits light upon collision of the electron beam are provided, and a hole for gas discharge other than the electron beam passage hole is provided in the electron beam extraction electrode.

Description of Embodiments An embodiment of the present invention will be described with reference to FIG. (The same symbols as those in the conventional example use the same symbols as those in the conventional example.) The same points as those in the conventional example are the back electrode 1, the line cathode 2 a-d, and the electron beam extraction electrode 11 having the electron beam passage holes 10 a-d. Is. The difference from the conventional example is that the electron beam extraction electrode 11 does not hit the electron beam from the line cathode, and avoid the position right in front of the line cathode between the line cathodes and between the electron beam passage holes of the electron beam extraction electrode. In addition, slit-shaped through holes 36a to 36c are provided in parallel with the line cathode for discharging gas. Needless to say, the through holes 36a to 36c do not have to be slit-shaped and may be arranged at appropriate intervals.

In this embodiment, a linear hot cathode in which (Ba, Ca, Sr) CO ₃ is applied as a thermionic emission material to a W wire having a diameter of 25 μm is used as the wire cathode. The distance between the back electrode 1 and the line cathode 2 is 0.3 mm,
The distance between the line cathode and the electron beam extraction electrode was also 0.3 mm. Fifteen linear cathodes are laid in parallel every 10 mm so that a 10 "image can be displayed. The electrodes sandwiching the linear cathode are 25 cm x 18 cm and are SUS43.
0 was used. These were built into the display device of the conventional example and housed in a flat glass bulb, and the wire cathode was simultaneously heated to a temperature of 800 to 900 while being evacuated to 10 ^-6 Torr by an oil diffusion pump.
The temperature was raised to 10 ° C. for about 10 seconds to activate the gas, and the gas generated during activation disappeared, so that the Ba getter was blown to the flat glass bulb wall and the chip was cut off to manufacture a 10 ″ display device.
A non-evaporable Zr getter is also placed inside the glass bulb. As a result, the initial electron beam emission characteristics of the line cathode before aging were improved, and the temperature was 630 ° C, and the electron beam emission characteristics were 3 to 5 mA / c.
It became 5 to 10 mA / cm from m. Further, as an operating condition of the line cathode of the display device of the present invention, about 1 mA / cm or more is required as an electron beam emission characteristic for use in the space charge limited region. That is, when the electron beam emission characteristic of the line cathode falls to about 1 mA / cm, the life of this device is reached. Therefore, the temperature of the line cathode is 700
The accelerated life test was performed at ℃.

As a result, in the past, the electron beam emission characteristics fell to 1 to 2 mA / cm within 300 hours, and even within a single line cathode, the characteristics varied and not only the display brightness of the screen decreased,
Although the brightness varied in places, in the display device of this example, the electron beam emission characteristics were 4 to 6 mA / cm even after 1000 hours, and there was no decrease or variation in brightness. The above is the fact that the gas generated by the rotation of the wire cathode is taken out from around the wire cathode by the through hole provided in the electron beam take-out electrode before poisoning the getter with the getter when aging the vacuum pump during activation. Because it was absorbed. In the flat panel display device in which it is difficult to form the gas discharge mechanism, the present invention discharges gas from the electron beam extraction electrode in front of the stretched wire hot cathode, that is, in the electron beam traveling direction. There is no gas retention on the surface of the electron beam emitting side, and it is possible to effectively prevent poisoning on the electron beam extraction electrode side of the linear cathode, which is important for generating the electron beam.

Furthermore, since the position of the through hole provided in the electron beam extraction electrode is provided between the electron beam passage holes avoiding in front of the line cathode where the electron beam hardly hits, the halo pattern caused by the stray beam does not occur, It did not adversely affect the beam characteristics of the beam.

EFFECTS OF THE INVENTION The display device of the present invention generates an electron beam by providing a through hole for discharging gas other than the electron beam passage hole in the electron beam extraction electrode in front of a plurality of stretched linear hot cathodes. It is possible to eliminate the poisoning on the electron beam extraction electrode side of the linear wire cathode by the generated gas, improve the electron beam emission characteristics, maintain the uniformity of image quality in the flat panel display device, and prolong the life of the display device. This greatly contributes to the realization of a high-performance flat panel display device.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing the basic structure of a conventional display device, FIG. 2 is an enlarged view of its screen, FIG. 3 is a block diagram showing the basic structure of a drive circuit of the device, and FIG. FIG. 3 is an exploded perspective view of a main part of the display device according to the embodiment of the invention. 2 ... Wire cathode as electron source, 3, 3 '... Electron beam extraction electrode, 4 ... Vertical deflection electrode, 5 ... Electron beam flow control electrode, 6 ... Horizontal focusing electrode, 7 ... Horizontal deflection electrode , 8 ... Electron beam acceleration electrode, 9 ... Screen, 2
0 ... Fluorescent material, 25 ... Vertical drive pulse generation circuit, 26
...... Line cathode drive circuit, 27 ...... Vertical deflection drive circuit, 28
...... Horizontal drive pulse generation circuit, 29 ...... Horizontal deflection drive circuit, 36 ...... Through hole.

Claims (1)

[Claims] 1. A plurality of stretched linear hot cathodes, a back body arranged behind the linear hot cathodes, and a front body arranged in front of the linear hot cathodes, and generated from the linear hot cathodes. The electron beam extraction electrode having a plurality of electron beam passage holes through which the electron beam passes, and the light emitting means for emitting light by the collision of the electron beam are provided, and the electron beam extraction electrode for discharging gas other than the electron beam passage holes. A display device having a hole.