JPH0479098B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for driving a flat panel image display device.

Configuration of Conventional Example and Its Problems First, a basic configuration example of the image display element used here will be described with reference to FIG.

This display element is arranged in order from the back to the front.
A back electrode 1, a line cathode 2 as a beam source, vertical focusing electrodes 3, 3', a vertical deflection electrode 4, a beam flow control electrode 5, a horizontal focusing electrode 6, a horizontal deflection electrode 7, a beam accelerating electrode 8 and a screen plate 9. They are housed within the evacuated interior of a flat glass bulb (not shown).

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, 2-2-4
(Only books shown) provided. In this embodiment, it is assumed that 15 pieces are provided. 2i~2ta. These line cathodes 2 have a diameter of, for example, 10 to 20 μφ.
An oxide cathode material is coated on the surface of a 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. )
The back electrode 1 may be formed by a coating of a conductive material applied to the inner surface of the rear wall of the glass bulb. Further, instead of the back electrode 1 and the linear cathode 2, a planar electron beam emitting cathode may be used.

The vertical focusing electrode 3 is a conductive plate 11 having a horizontally long slit 10 facing each of the line cathodes 2a to 2ta, and takes out the electron beam emitted from the line cathode 2 through the slit 10 and directs the electron beam vertically. focus in a direction. (The slit 10 may be provided with crosspieces at appropriate intervals in the middle, or may be a row of many through holes arranged horizontally at small intervals (almost touching), and can be used as a slit. (may be configured). The vertical focusing electrode 3' is also similar.

A plurality of vertical deflection electrodes 4 are arranged horizontally in the middle of each of the slits 10, and are each composed of conductors 13 and 13' provided on the upper and lower surfaces of an insulating substrate 12. has been done. And the opposing conductors 13, 13'
A vertical deflection voltage is applied between them to deflect the electron beam in the vertical direction. In this embodiment, the electron beam from one line cathode 2 is vertically deflected to positions corresponding to 16 lines by a pair of conductors 13, 13'. And, by 16 vertical deflection electrodes 4, 15
Fifteen conductor pairs corresponding to each of the book line cathodes 2 are constructed, and the electron beam is ultimately deflected to draw 240 horizontal lines on the screen 9.

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 15n for control electrodes are provided (only 10 are shown in the figure). (Each of the control electrodes 5 extracts the electron beam horizontally by dividing it into one picture element at a time, and controls the amount of the electron beam passing therethrough in accordance with the video signal for displaying each picture element.)
Therefore, if 320 control electrodes 5 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 phosphors of three colors, G and B, and the R, G, and B video signals are sequentially applied to each control electrode 5. In addition, 320 sets of video signals for one line are simultaneously applied to the 320 control electrodes 5, 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 vertically long slits 16 facing the slits 14 of the control electrode 5, 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 is composed of a plurality of conductive plates 18 arranged vertically in the middle of each of the slits 16, and a horizontal deflection voltage is applied between each conductive plate 18 for each picture element. The electron beams are respectively deflected in the horizontal direction, and the R, G, and B phosphors are sequentially irradiated on the screen 9 to cause them to emit light. In this embodiment, the deflection range is the width of one picture element 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, and accelerates the electron beam so that it collides with the screen 9 with sufficient energy.

The screen 9 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 arranged for each slit 14 of the control electrode 5, that is, for each horizontally divided electron beam.
Pairs of phosphors of three colors, R, G, and B, are provided and are applied in stripes in the vertical direction. 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 5. Indicates the horizontal division displayed. As shown in the enlarged view in Figure 2, one section partitioned by these two has R, G, and B phosphors 20 for one picture element in the horizontal direction, and 16 lines in the vertical direction. It has a width.
For example, the size of one section is 1 in the horizontal direction.
mm, and the vertical direction is 16 mm.

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

Next, the basic configuration of a drive circuit for displaying television images on this display element 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 element,
-V ₁ to the back electrode 1, and -V 1 to the vertical focusing electrodes 3 and 3'.
DC voltages of V ₃ , V ₃ ', V ₆ to the horizontal focusing electrode 6, V ₈ to the accelerating electrode 8, and V ₉ to the screen 9 are applied.

Next, a composite video signal of a television signal is applied to the input terminal 23, and a synchronization separation circuit 24 separates and extracts a vertical synchronization signal V and a horizontal synchronization signal H. The vertical drive pulse generation circuit 25 is composed of a counter that is reset by a vertical pulse and counts horizontal pulses, and is configured to operate during an effective vertical scanning period (here, 240 hours) excluding the vertical retrace period of the vertical period. 15 drive pulses, each having a length of 16H period, are generated sequentially during the following period. This drive pulse rotor is applied to the line cathode drive circuit 26, where it is inverted so that it is brought to a low potential only during each pulse period and approximately 20
A line cathode drive pulse I′ made at a high potential of volts,
It is converted into B′...T′, and each line cathode 2a, 2b,...
...Added to 2 ta. Each line cathode 2a...2ta is heated by a current flowing through it during the high potential of the drive pulses I' to T', so that it can emit electrons even during the low potential period of the drive pulses I' to T'. The heated state is maintained. As a result, electrons are emitted from the 15 line cathodes 2i to 2ta only during the 16H period in which low potential drive pulses i' to ta' are applied to each of them.

During the period when a high potential is applied, the back electrode 1
This is because the high potential applied to the line cathodes 2A to 2T becomes more positive than the potential at the position of the line cathode 2, which is determined by the bias voltage applied to the line cathode 2 and the vertical focusing electrode 3. , electrons are not emitted from the line cathodes 2a to 2a. Thus, line cathode 2
During the effective vertical scanning period, 16H is sequentially applied from the upper line cathode 2a to the lower line cathode 2a.
Electrons are emitted for each period. 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 synchronization signal reset by each of the vertical drive pulse generators, a conversion circuit that converts the count output from D/A, and the like. During the 16H period of each vertical drive pulse generator, a pair of vertical deflection signals V and V' are generated which change in 16 steps by 1H. The vertical deflection signals V and V' both have a center voltage of _V4 , and are configured to change in opposite directions so that V increases sequentially and V' decreases sequentially. These vertical deflection signals V and V' are applied to electrodes 13 and 13' of the vertical deflection electrode 4, respectively, and as a result, the electron beams generated from the respective line cathodes 2a to 2a are deflected in 16 steps in the vertical direction. As mentioned above, on the screen 9, one electron beam is deflected so as to sequentially draw a raster line of 16 lines one line at a time from the top.

As a result of the above, electron beams are emitted from the top of the 15 line cathodes 2A to 2T for a period of 16 hours, and each electron beam is sequentially emitted for one line from the top to the bottom within the 15 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 top end to the 240th line at the bottom end, and a total of 240 lines of raster are drawn.

The electron beam thus vertically deflected is horizontally deflected by 320 degrees by the control electrode 5 and the horizontal focusing electrode 6.
It is divided into sections and taken out. Figure 1 shows one of these categories. The amount of electron beam passing through each section is controlled by a control electrode 5, and horizontally focused by a horizontal focusing electrode 6 into a single narrow electron beam, which is then controlled by horizontal deflection means described below. The R, G, and B phosphors 2 on the screen 9 are deflected horizontally in three steps.
0 is sequentially irradiated.

That is, the horizontal drive pulse generation circuit 28 is composed of three cascade-connected monostable multivibrators, etc., and is triggered by a horizontal synchronization signal to generate three horizontal drives with equal pulse widths within one horizontal period. Generate pulses r, g, b. Here, as an example, each pulse width is approximately 17 μsec.
As, 3 during the active horizontal scanning period of 50μsec.
Three pulses r, g, and b are generated. These horizontal drive pulses r, g, and b are applied to the horizontal deflection drive circuit 29. The horizontal deflection drive circuit 29 generates a pair of horizontal deflection signals h and h' that change in three stages by being switched by the horizontal drive pulses r, g, and b. Both horizontal deflection signals h and h' have a center voltage of V ₇ , and h increases sequentially,
h' change in opposite directions so that they decrease sequentially. These horizontal deflection signals h, h' are applied to electrodes 18 and 18' of the horizontal deflection electrode 7, respectively.
As a result, each horizontally divided electron beam is horizontally deflected so as to sequentially irradiate the R, G, and B phosphors of the screen 9 for 17 μsec during each horizontal period. However, in the display element of FIG. 1, one conductor 16 or 18' is used in the horizontal deflection electrode 7.
is used to deflect the electron beams of two adjacent sections, and is designed to produce a deflection effect on the adjacent electron beams in mutually opposite directions. Therefore, the electron beam of 320 sections is If the item in the th division is deflected in the order of R → G → B, the item in the even numbered division is deflected in the order of B → G → R, and so on, every other division is deflected in the opposite direction. be done.

Thus, in each line raster, the electron beam is divided into R, G,
Each of the B phosphors 20 is sequentially irradiated with light.

Therefore, a color television image can be displayed on the screen 9 by modulating the electron beam with R, G, and B video signals for each horizontal section of each line.

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

First, the composite video signal applied to the television signal input terminal 23 is applied to the color demodulation circuit 30,
Here, the color difference signals of R-Y and B-Y are demodulated,
The G-Y color difference signals are matrix-synthesized, and then they are combined with the luminance signal Y to generate R, G,
B primary color signals (hereinafter referred to as R, G, and B video signals) are output. These R, G, and B video signals are processed by 320 sample and hold circuit sets 31a to 3.
Added to 1n. Each sample hold circuit group 3
1a to 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 held by memory sets 32a to 32n, respectively.
32n.

On the other hand, the sampling reference clock oscillator 33
is composed of a PLL (phase locked loop) circuit, etc., and generates a reference clock of about 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. The reference clock is applied to the sampling pulse generation circuit 34, where it is delayed by one clock cycle by a shift register, etc., and is applied to the sampling pulse generator 34 for 320 seconds during the effective horizontal scanning period (approximately 50 μsec) of the horizontal period (63.5 μsec). Sampling pulses a to n are sequentially generated, and then one transfer pulse is generated. These sampling pulses a to n correspond to each picture element when one line of the video to be displayed is divided horizontally into 320 picture elements, and their positions are always constant with respect to the horizontal synchronizing signal H. controlled by.

These 320 sampling pulses a to n correspond to the above 320 sample and hold circuit sets 31.
a to 31n, thereby providing one line to each sample and hold circuit set 31a to 31n.
When divided into 320 picture elements, the R, G, and B video signals of each picture element are individually sampled and held. The sample-held 320 sets of R, G, B video signals are stored in 320 sets of memory 32a~
32c by a transfer pulse t,
Here, it is held for the next one horizontal period.

One line of R, G, and B video signals held in the memories 32a to 32n are applied to 320 switching circuits 35a to 35n, respectively. The switching circuits 35a to 35n each have R, G,
B individual input terminals and a common output terminal that sequentially switches and outputs them, and the output of each switching circuit 35a to 35n is sent to the control electrode 5 of the display element as a control signal for modulating the electron beam.
are individually applied to each of the 320 conductive plates 15a to 15n. Each switching circuit 35a to 35
n are simultaneously switched and controlled by a switching pulse applied from a switching pulse generating circuit 36. The switching pulse generation circuit 36 receives pulses r,
The switching circuits 35a-35n are controlled by R, G,
Each video signal of B is time-divided and outputted alternately and sequentially,
Switching signals r, g, and b are generated to be supplied to control electrodes 15a to 15n. However, among the switching circuits 35a to 35n, the odd-numbered switching circuits 35a, 35c, . . . are switched in the order of R→G→B, and the even-numbered switching circuits 35a, 35c...
5a, 35d...35n are configured to be switched in the reverse order of B→G→R.

What should be noted here is that the switching circuit 3
The switching of the supply of R, G, and B video signals in 5a to 35n and the horizontal deflection of the electron beam irradiation to the R, G, and B phosphors by the horizontal deflection drive circuit 29 are completely performed in both timing and order. It is synchronously controlled to match. 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 B 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 on 240 lines starting from the upper line to display one video on screen 9. will be done.

The above operations are repeated for each field of the input television signal, and as a result,
The screen 9 is similar to a normal television receiver.
The television footage of the video is shown above.

In the flat panel image display device as described above, there is a problem of defocusing due to deflection of the electron beam. This is caused by beam focusing aberrations caused by electrostatic deflection, which is common in electrostatic deflection in general, and also by the electrode structure of the flat panel image display device of the present invention. The former occurs because an electron beam with a certain spread is deflected,
Vertical deflection causes vertical defocus, and horizontal deflection causes horizontal defocus. The latter is mainly caused by the beam accelerating electrode 8. That is, the vertical defocus due to vertical deflection caused by the aberration of the vertical electrostatic lens formed by the beam accelerating electrode 8, and the effect of the horizontal electrostatic lens of the horizontal deflection electrode 7 cause the beam accelerating electrode 8 to become blurred. Due to the influence of high voltage, it is not uniform at each position in the vertical direction. Therefore, vertical deflection causes horizontal defocus.

OBJECTS OF THE INVENTION It is an object of the present invention to eliminate the defocusing caused by deflection of an electron beam as described above and to improve image quality.

Structure of the Invention In order to achieve the above object, the present invention is characterized in that dynamic focusing is performed by the following method.

Here, the description will be made by considering a vertical deflection electrode as the first deflection means and a horizontal deflection electrode as the other deflection means. The vertical deflection electrode and the horizontal deflection electrode are deflection electrodes and at the same time constitute vertical and horizontal focusing lenses, respectively. Focusing can be achieved by: (a) changing the center voltage of the vertical deflection signal applied to the vertical deflection electrodes as the vertical deflection occurs;

(b) Changing the center voltage of the horizontal deflection signal applied to the horizontal deflection electrode along with the vertical deflection.

(c) Changing the center voltage of the horizontal deflection signal applied to the horizontal deflection electrode as the horizontal deflection occurs.

(a) above is dynamic focusing for vertical defocus associated with vertical deflection, (b) is dynamic focusing for horizontal defocus associated with vertical deflection, and (c) is horizontal convergence associated with horizontal direction. It is.

Therefore, by performing (a), (b), and (c) in combination, dynamic focusing can be performed for all of the defocus in the vertical and horizontal directions due to vertical deflection and the defocus in the horizontal direction due to horizontal deflection. is possible. In other words, a uniform spot diameter can be obtained over the entire screen.

DESCRIPTION OF EMBODIMENTS An embodiment in which television images are displayed on the flat panel image display device of the present invention will be described.

FIG. 4 shows an example of dynamic focusing for vertical defocus associated with vertical deflection according to the present invention. v and v' are a pair of vertical deflection signals such that v sequentially increases and v' sequentially decreases in 16 steps of 1H each during a 16H period under the center voltage _V2 .

V ₂ is synchronized with v and v′ and is 16 times each 1H of 16H period.
It is a voltage signal that changes in stages, and the voltage of each stage is adjusted individually. v and v′ become v and v′
It is a pair of voltage signals with V ₂ added, and the center voltage is V ₂ +V ₂ . Therefore, by individually adjusting the voltage value of each stage of _V2 , the center voltage of v and v' can be adjusted for each stage.

By using such v and v' in the vertical deflection signal, dynamic focusing is performed against vertical defocus caused by vertical deflection.

FIG. 5 shows an example of dynamic focusing for horizontal defocus associated with vertical deflection according to the present invention. h and h' are a pair of horizontal deflection signals in which h increases sequentially and h' sequentially decreases in three stages during an effective horizontal scanning period within one horizontal period (1H period) under the center voltage _V7 . be. Like V ₂ , V ₇ is a voltage signal that changes in 16 steps every 1H during a 16H period.
The voltage of each stage is adjusted individually. h and h' are a pair of voltage signals obtained by adding V ₇ to h and h', and the center voltage thereof is V ₇ +V ₇ . Therefore
By adjusting the voltage value of each stage of V ₇ individually
The center voltage of h and h′ can be adjusted for each stage. By using such h and h' as horizontal deflection signals, dynamic focusing is performed against horizontal defocus caused by vertical deflection.

FIG. 6 shows an example of dynamic focusing for horizontal defocus caused by horizontal deflection according to the present invention. _V7 is a voltage signal that changes in three stages during an effective horizontal scanning period within one horizontal period (1H period) in synchronization with h and h', and the voltage at each stage is adjusted individually. h and h′ are a pair of voltage signals obtained by adding V ₇ to h and h′, and their center voltage is V ₇
+V ₇ +V ₇ . Therefore, by individually adjusting the voltage value of each stage of _V7 , the center voltage of h and h' can be adjusted for each stage. h like this
By using h' and h' as horizontal deflection signals, dynamic focusing is performed for horizontal defocus caused by vertical deflection, and at the same time, dynamic focusing is performed for horizontal defocus caused by horizontal deflection.

Note that the voltage values of each stage of V ₂ , V ₇ , and V ₇ were adjusted individually, but once the electrode configuration and the voltage applied to each electrode are determined, V ₂ , V ₇ , and V ₇ are also determined, and in this case, There is no need to adjust each stage individually.

Also, if V ₂ , V ₇ , and V ₇ are determined, v and v′,
h and h′ are also determined, and the vertical deflection signals v and
It is also possible to set v', horizontal deflection signals h and h' to v and v', h and h' in advance.

Effects of the Invention The method for driving a flat panel image display device of the present invention can eliminate defocus caused by deflection.

[Brief explanation of the drawing]

Figure 1 is a basic configuration diagram of a flat panel image display device.
Fig. 2 is an enlarged view of the main part of the phosphor film on the screen in the same device, Fig. 3 is a diagram showing the basic driving method of the device, and Figs. It is an explanatory diagram of an example. 2... Line cathode (electron beam source), 3... Vertical focusing electrode (electron beam extraction means), 4... Vertical deflection electrode (vertical deflection means), 5... Control electrode (electron beam control means), 7... ...Horizontal deflection electrode (horizontal deflection means), 9...Screen plate (light emitting means).

Claims (1)

[Claims] 1 Line cathodes as linear electron beam sources arranged in multiple rows, electron beam extraction means for extracting electron beams from the line cathodes, and electron beam control for controlling the electron beams. A method for driving a flat panel image display device comprising: a deflection means for deflecting an electron beam; and a light emitting means that emits light upon impact of the electron beam, the center voltage of a deflection signal applied to the deflection means being A method for driving a flat panel image display device, characterized in that the method changes according to the deflection. 2. The deflection means is composed of a plurality of deflection means, and the center voltage of the deflection signal applied to the first deflection means among the deflection means is controlled by at least one of the first deflection means or the other deflection means. 2. The method of driving a flat panel image display device according to claim 1, wherein the driving method is changed according to the deflection of the beam. 3. The deflection means is composed of a plurality of deflection means, and the center voltage of the deflection signal applied to the first deflection means is controlled by at least the first deflection means or other deflection means. 2. The method of driving a flat panel image display device according to claim 1, wherein the driving method is changed according to the deflection of the electron beam.