JP4138076B2 - Driving method of flat image display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a driving method of a flat image display device in video equipment.
[0002]
[Prior art]
As a flat image display device, an electron beam is focused, modulated and deflected by a flat electrode unit in which an electron beam source and a plurality of electron beam control electrodes are stacked, and an image is obtained by irradiating and emitting an electron beam on a phosphor screen. A method for displaying the image has been developed.
[0003]
A driving method for a flat-type image display device is proposed in Japanese Patent Application Laid-Open No. 1-296543 (Japanese Patent Application No. 63-125284).
[0004]
FIG. 7 shows an exploded perspective view of a main configuration of a conventional flat image display apparatus. As shown in FIG. 7, the flat-type image display apparatus includes a back electrode 1, a line cathode (cathode) 2 as an electron beam source, an electron beam extraction electrode 3, a signal electrode 4, a focusing electrode 5, a horizontal deflection electrode 6, and a vertical. The components composed of the deflection electrodes 7a and 7b are housed in a container composed of a glass container 8 and a back container 9, and the interior of the container is configured as a vacuum.
[0005]
The back electrode 1 is made of a flat conductive material and is provided in parallel to the line cathode 2.
[0006]
The line cathode 2 is stretched in the horizontal direction so as to generate an electron current having a substantially uniform current density distribution in the horizontal direction, and a plurality of lines (three in the example of FIG. 7 in the vertical direction) are arranged at appropriate intervals. Only shown). These wire cathodes 2 are configured, for example, by coating an oxide cathode material on the surface of a tungsten wire.
[0007]
The extraction electrode 3 is composed of a conductive plate 11 and is opposed to the back electrode 1 via the line cathode 2 and has a row of through-holes 10 provided at appropriate intervals in the horizontal direction on the horizontal line facing each line cathode. The electron beam emitted from the line cathode 2 passes through the through hole 10 and is extracted in a fixed direction to control the amount of electron beam.
[0008]
The signal electrode 4 is composed of a row of vertically elongated conductive plates 12 arranged at predetermined positions at positions facing each of the through-holes 10 arranged in the horizontal direction in the extraction electrode 3. The plate 12 has a similar through hole 13 at a position opposite to the through hole 10 of the extraction electrode 3. The signal electrode 4 controls the passage of the electron beam through the through hole 13 based on the video signal.
[0009]
The focusing electrode 5 includes a conductive plate 15 having a through hole 14 at a position facing the through hole 13 of the signal electrode 4 and controls the size of the electron beam.
[0010]
The horizontal deflection electrode 6 is configured so as to form a pair of horizontal deflection electrodes by disposing elongated conductive plates 16a and 16b in the vertical direction on the same plane so as to face the middle of the row of through holes 14 of the focusing electrode 5. As a whole, it has a fence shape. The electron beam is deflected in the horizontal direction by the conductive plates 16a and 16b.
[0011]
The vertical deflection electrodes 7a and 7b have a configuration in which two comb-like conductive plates are meshed with each other at an appropriate interval on the same plane. For example, for the electron beam 17, a lower conductive plate 18a and an upper The conductive plate 18b forms a pair of vertical deflection electrodes, and these conductive plates 18a and 18b deflect the electron beam in the vertical direction.
[0012]
The screen 19 is configured by applying a phosphor 20 that emits light when irradiated with an electron beam to the inner surface of, for example, a glass container 8 and adding a metal back layer (not shown) thereon.
[0013]
An electrode unit 22 is formed by laminating a plurality of conductive plates from the extraction electrode 3 to the vertical deflection electrodes 7a and 7b. The electron beam 17 emitted from the line cathode 2 passes through through holes 10, 13, and 14 provided in the extraction electrode 3, the signal electrode 4, and the focusing electrode 5, respectively, and the horizontal deflection electrode 6 and the vertical deflection electrodes 7 a and 7 b. The screen 19 is irradiated via the.
[0014]
In this image display device, the seams of adjacent image subsections 21 on the screen 19 are not visible, and each electrode is processed with high precision when processing and assembling the electrodes in order to obtain a highly uniform image. It is manufactured by processing and positioning.
[0015]
Next, a horizontal sectional view of a conventional flat image display device is shown in FIG. Hereinafter, the same parts as those in the conventional example of FIG. In FIG. 8, the anode 23 is a region where a high voltage can be applied by applying a metal back on the phosphor 20 of the screen 19. The glass container side wall 24 keeps the space between the glass container 8 and the back container 9 constant, and vacuum-shields the space.
[0016]
FIG. 9 shows the voltage distribution on the inner surface of the flat image display device. The anode voltage VA is a voltage applied to the anode 23, and is a voltage of several kilovolts to several tens of kilovolts. The glass container side wall voltage V24 is the voltage of the glass container side wall 24. The glass side wall voltage V24 is in the vicinity of 0 volts as an initial value unless the flat image display device is driven. When the flat-type image display device is driven, the glass container side wall voltage V24 changes over time from several kilovolts to near the anode voltage VA due to charge-up by the action of the anode voltage VA and the action of secondary electrons by the electron beam 17. The steady state is reached after a certain period of time.
[0017]
Next, a method for driving a conventional flat image display apparatus will be described.
[0018]
FIG. 10 shows a driving timing chart showing how each electrode voltage is driven when the power source SW (switch) is turned off. As shown in FIG. 10, when the power supply SW is switched from ON to OFF at timing T1, the anode voltage is from the drive voltage VA, the signal electrode voltage is from the drive voltage VG4, the extraction electrode voltage is from the drive voltage VG3, and the line cathode The voltage (cathode heating voltage) drops from the driving voltage VK to 0 volts at the timing T1. At this time, the temperature of the wire cathode (cathode) 2 was the cathode heating temperature TK until the timing T1, but decreases to the room temperature TR (20 to 30 ° C.) over time until the timing T3. Therefore, the amount of thermoelectrons emitted from the line cathode also gradually decreases after the timing T1 has elapsed.
[0019]
The behavior of the electron beam when the flat image display device is driven by such a driving method is shown in FIGS. 11 and 12 as horizontal sectional views.
[0020]
FIG. 11 is a horizontal cross-sectional view showing the behavior of the electron beam when the power supply SW is turned from ON to OFF. When the power supply SW is turned on and is in a steady state, the electron beam trajectory 26 is passed. However, when the power supply SW is turned off, the anode voltage becomes 0 volt and the charge voltage on the glass container side wall 24 becomes the highest voltage. The beam passes through the electron beam trajectory 27 and hits the glass container side wall 24 to cause a voltage drop on the glass container side wall.
[0021]
FIG. 12 is a horizontal cross-sectional view showing the behavior of the electron beam when the power supply SW is turned on from OFF. Immediately after the power supply SW is turned on, the difference between the anode voltage and the glass container side wall voltage is large due to the voltage drop on the glass container side wall 24 described in FIG. 11, so that the electron beam passes through the electron beam trajectory 25 near the center of the screen. When the charging voltage of the glass container side wall 24 reaches a steady state, the normal electron beam trajectory 26 is passed.
[0022]
[Problems to be solved by the invention]
Therefore, the phenomenon shown in FIGS. 11 and 12 is repeated every time the power supply SW is turned on and off, and the initial electron beam trajectory when the power supply SW is turned on is not stabilized, and image quality deterioration due to color misregistration occurs.
[0023]
In the conventional driving method, the temperature of the line cathode (cathode) does not drop immediately after the power SW is turned off. Therefore, after the power SW is turned off, the leaked electron beam jumps in the vacuum vessel, and the voltage on the side wall of the glass vessel is around 0 V in the initial state. Will be reduced. In order to prevent this, it is necessary to maintain the charged state without causing a voltage drop on the glass container side wall so that the leaked electron beam does not hit the glass container side wall after the power supply SW is turned off.
[0024]
Accordingly, a first object of the present invention is to solve these problems and reduce initial image quality deterioration when the power SW of the flat image display device is turned on.
[0025]
The second object of the present invention is to solve these problems and to further reduce the initial image quality deterioration when the power supply SW of the flat image display device is turned on.
[0026]
[Means for Solving the Problems]
In order to achieve the above object, a driving method of a flat-type image display device according to a first aspect of the present invention includes a back electrode and a screen in a flat glass container whose inside is a vacuum, and the back electrode A flat-type image display device having a line cathode and a plurality of electrode plates stacked between the screen and the screen, the anode voltage being compared with the line cathode voltage when the power switch is turned off. It is characterized by being delayed for a certain time.
[0027]
According to a second aspect of the present invention, there is provided a driving method for a flat-type image display device having a back electrode and a screen in a flat glass container having a vacuum inside, and the space between the back electrode and the screen. A flat-type image display device driving method comprising a line cathode and a plurality of electrode plates stacked, wherein when the power switch is turned off, the anode voltage and the extraction electrode voltage are constant for a certain time compared to the line cathode voltage. It is characterized by cutting after a delay.
[0028]
According to the driving method of the flat-type image display device of the first aspect of the present invention, when the power switch is turned off, the anode voltage is turned off with a certain time delay compared to the line cathode voltage, so that it passes through the electrode unit. The electron beam is absorbed by the anode. Therefore, the potential of the glass container wall surface is not greatly reduced, and image quality deterioration when the power supply SW is turned on next time can be reduced.
[0029]
Further, according to the driving method of the flat-type image display device of the second aspect of the present invention, when the power switch is turned off, the anode voltage and the extraction electrode voltage are cut off with a certain delay from the line cathode voltage. The electron beam jumping out from the line cathode is attracted to the electrode unit, and the electron beam does not jump out from the line cathode directly onto the wall surface of the glass container. The electron beam entering the electrode unit is absorbed by the electrode unit, or after passing through the electrode unit, is absorbed by the anode. Therefore, the potential of the glass container wall surface is not lowered, and the image quality deterioration when the power supply SW is turned on next time can be greatly reduced.
[0030]
In the second invention, the signal electrode voltage is preferably cut off at the same timing as the line cathode voltage. According to such a preferable configuration, since the probability that the electron beam that has passed through the extraction electrode is pulled back to the extraction electrode and absorbed is increased, the proportion of the electron beam that is absorbed by the electrode unit can be increased.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0032]
(Embodiment 1)
FIG. 1 is a drive timing chart according to the first embodiment.
[0033]
As shown in FIG. 1, when the power supply SW is switched from ON to OFF at timing T1, the anode voltage drops to 0 volts after maintaining the drive voltage VA until timing T4. On the other hand, the signal electrode voltage drops from the drive voltage VG4, the extraction electrode voltage drops from the drive voltage VG3, and the line cathode voltage (cathode heating voltage) drops from the drive voltage VK to 0 volts at timing T1, respectively. At this time, the temperature of the wire cathode, which was the cathode heating temperature TK until timing T1, decreases to room temperature TR (20 to 30 ° C.) over time until timing T3. Here, timing T4 may be any timing after timing T2 when the thermal electron emission characteristics of the line cathode deteriorate.
[0034]
With the above driving timing, when the power switch is turned off, the anode voltage is turned off after a certain time compared to the line cathode voltage, that is, the anode voltage is set to 0 V after the timing T2 when the thermoelectron emission characteristic of the line cathode falls. Therefore, the electron beam that has passed through the electrode unit after timing T1 is absorbed by the anode. Therefore, the potential of the glass container wall surface is not greatly reduced.
[0035]
FIG. 2 is a horizontal cross-sectional view showing the behavior of the electron beam when the power supply SW is turned on from OFF in the first embodiment.
[0036]
In the present embodiment, a voltage drop on the wall surface of the glass container hardly occurs even when the power SW is turned off. Therefore, the difference between the anode voltage immediately after the power supply SW is turned on and the glass container side wall voltage is reduced, and as shown in FIG. 2, the steady state electron beam from the electron beam trajectory 28 immediately after the power supply SW is turned on. The change to the trajectory 26 is reduced, and initial image quality degradation is improved.
[0037]
(Embodiment 2)
In the first embodiment, after the power source SW is turned off, the electron beam that has passed through the electrode unit can be absorbed by the anode, and in this respect, a voltage drop on the wall surface of the glass container is prevented compared to the conventional technique. can do. However, not all electron beams that jump out of the line cathode after turning off the power SW pass through the electrode unit. The electron beam that does not pass through the electrode unit cannot be absorbed by the anode, and if it collides with the glass container wall surface, a voltage drop occurs.
[0038]
FIG. 3 is a horizontal sectional view showing an example of the behavior of the electron beam when the power supply SW is turned off in the first embodiment.
[0039]
As shown in FIG. 3, immediately after the power SW is turned off, an electron beam may jump out from the line cathode toward the glass container side wall 24 through the electron beam trajectory 29. For this reason, the potential of the glass container side wall is lowered, and as shown in FIG. 2, the electron beam trajectory 28 immediately after the power supply SW is turned on and the electron beam trajectory 26 in the steady state cannot be completely matched.
[0040]
The second embodiment can suppress the voltage drop on the glass container wall surface caused by the electron beam shown in FIG.
[0041]
FIG. 4 is a drive timing chart in the second embodiment.
[0042]
As shown in FIG. 4, when the power supply SW is switched from ON to OFF at timing T1, the anode voltage maintains its driving voltage VA and the extraction electrode voltage maintains its driving voltage VG3 until timing T4. descend. On the other hand, the signal electrode voltage drops from the drive voltage VG4, and the line cathode voltage (cathode heating voltage) drops from the drive voltage VK to 0 volts at timing T1, respectively. At this time, the temperature of the wire cathode, which was the cathode heating temperature TK until timing T1, decreases to room temperature TR (20 to 30 ° C.) over time until timing T3. Here, timing T4 may be any timing after timing T2 when the thermal electron emission characteristics of the line cathode deteriorate.
[0043]
FIG. 5 is a horizontal cross-sectional view showing the behavior of the electron beam when the power SW is turned off in the second embodiment.
[0044]
As shown in FIG. 5, since the extraction electrode maintains the voltage of VG3 immediately after the power supply SW is turned off, the electron beam emitted from the line cathode is attracted to the electrode unit 22 through the electron beam trajectory 30. The electron beam entering the electrode unit directly hits the electrode unit or passes through the through hole of the extraction electrode. A portion of the electron beam that has passed through the through hole of the extraction electrode is pulled back to the extraction electrode and absorbed by the electrode unit because the signal electrode is at 0 volts. Further, the electron beam that has passed through the electrode unit without being pulled back to the extraction electrode is absorbed by the anode. As a result, the possibility that an electron beam that jumps out of the line cathode immediately after the power SW is turned off can collide with the wall surface of the glass container. As a result, the potential drop of the glass container wall surface due to the collision of the electron beam after the power source SW is turned off can be greatly suppressed.
[0045]
FIG. 6 is a horizontal cross-sectional view showing the behavior of the electron beam when the power supply SW is turned on from OFF in the second embodiment.
[0046]
In the present embodiment, even if the power SW is turned off, the voltage drop on the wall surface of the glass container hardly occurs. Therefore, the difference between the anode voltage immediately after the power supply SW is turned on and the glass container side wall voltage becomes extremely small, and the electron beam trajectory immediately after the power supply SW is turned on is in a steady state as shown in FIG. It almost coincides with the trajectory 26, and the initial image quality degradation is greatly improved.
[0047]
【The invention's effect】
According to the driving method of the flat-type image display device of the first aspect of the present invention, when the power switch is turned off, the anode voltage is turned off with a certain time delay compared to the line cathode voltage, so that it passes through the electrode unit. The electron beam is absorbed by the anode. Therefore, the potential of the glass container wall surface is not greatly reduced, and image quality deterioration when the power supply SW is turned on next time can be reduced.
[0048]
Further, according to the driving method of the flat-type image display device of the second aspect of the present invention, when the power switch is turned off, the anode voltage and the extraction electrode voltage are cut off with a certain delay from the line cathode voltage. The electron beam jumping out from the line cathode is attracted to the electrode unit, and the electron beam does not jump out from the line cathode directly onto the wall surface of the glass container. The electron beam entering the electrode unit is absorbed by the electrode unit, or after passing through the electrode unit, is absorbed by the anode. Therefore, the potential of the glass container wall surface is not lowered, and the image quality deterioration when the power supply SW is turned on next time can be greatly reduced.
[0049]
Furthermore, in the above second invention, since the signal electrode voltage is cut off at the same timing as the line cathode voltage, the probability that the electron beam that has passed through the extraction electrode is drawn back to the extraction electrode and absorbed is increased. The ratio of the electron beam absorbed by the electrode unit can be increased.
[0050]
In addition, said effect expresses in the period when the charge of a container inner surface is maintained. If you do not drive for days, the effect disappears. Therefore, the effect of the present invention is particularly remarkable when the power supply SW is turned on and off every day.
[Brief description of the drawings]
FIG. 1 is a drive timing chart of a flat-type image display device according to a first embodiment of the present invention.
FIG. 2 is a horizontal sectional view showing the behavior of an electron beam when a power supply SW is turned on in the first embodiment of the present invention.
FIG. 3 is a horizontal cross-sectional view showing the behavior of an electron beam when a power supply SW is turned off in the first embodiment of the present invention.
FIG. 4 is a drive timing chart of the flat image display apparatus according to the second embodiment of the present invention.
FIG. 5 is a horizontal cross-sectional view showing the behavior of an electron beam when a power supply SW is turned off in a second embodiment of the present invention.
FIG. 6 is a horizontal cross-sectional view showing the behavior of an electron beam when a power supply SW is turned on in the second embodiment of the present invention.
FIG. 7 is an exploded perspective view showing the main configuration of the flat image display apparatus.
8 is a horizontal cross-sectional view of the flat image display apparatus of FIG.
9 is a horizontal sectional view showing a voltage distribution on the inner surface of the container of the flat-type image display device of FIG.
FIG. 10 is a driving timing chart in the driving method of the conventional flat image display apparatus.
FIG. 11 is a horizontal cross-sectional view showing the behavior of an electron beam when a power supply SW is turned off in a conventional method for driving a flat-type image display device.
12 is a horizontal cross-sectional view showing the behavior of an electron beam when a power supply SW is turned on in a conventional driving method for a flat-type image display device. FIG.
[Explanation of symbols]
1 Rear electrode 2 Wire cathode (cathode)
3 Electron beam extraction electrode 4 Signal electrode 5 Focusing electrode 6 Horizontal deflection electrodes 7a and 7b Vertical deflection electrode 8 Glass container 9 Back container 17 Electron beam 19 Screen 20 Phosphor 22 Electrode unit 23 Anode 24 Glass container side walls 25, 26, 27, 28, 29, 30 Electron beam trajectory

Claims (3)

A flat-type image display apparatus having a back electrode and a screen in a flat glass container having a vacuum inside, and having a plurality of electrode plates laminated with a line cathode between the back electrode and the screen. A driving method for a flat-type image display device, characterized in that when the power switch is turned off, the voltage of the anode is turned off with a certain delay from the line cathode voltage. A flat-type image display apparatus having a back electrode and a screen in a flat glass container having a vacuum inside, and having a plurality of electrode plates laminated with a line cathode between the back electrode and the screen. A driving method for a flat-type image display device, characterized in that when the power switch is turned off, the anode voltage and the extraction electrode voltage are turned off with a certain delay from the line cathode voltage. The driving method of the flat-type image display device according to claim 2, wherein the signal electrode voltage is cut at the same timing as the line cathode voltage.

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