JP2001174787A - Plasma address display device and driving method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the display quality by suppressing irregular discharges of a plasma address display device. SOLUTION: The plasma address display device uses a flat panel 0 wherein a display cell with signal electrodes Y arranged in column and a plasma cell with discharge channels 5 arranged in rows and comprising anode electrodes A and cathode electrodes K are layered, and wherein pixels 11 are arranged at respective intersections of respective signal electrodes Y and respective discharge channels 5. To drive this, this device has a scanning circuit 22 for sequentially discharging each channel 5 by applying a prescribed voltage to the cathode electrodes K with respect to the anode electrodes A and selecting the pixels 11 row by row, and a signal circuit 21 for sequentially supplying image signals to column-formed signal electrodes Y in synchronization with the discharges and writing the image signals in the pixels 11 of the selected row. When the scanning circuit 22 applies a prescribed voltage to the cathode electrodes K necessary for discharge with reference to the anode electrodes A for a prescribed period required for discharge, the circuit 22 suppresses irregular discharges by supplying trigger voltages exceeding the prescribed voltage to the discharge channels only for a limited initial period of the application.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma addressed display device in which a display cell and a plasma cell are overlapped. More specifically, the present invention relates to a scanning circuit configuration and a scanning method for suppressing irregular discharge of a plasma cell.

[0002]

2. Description of the Related Art A plasma addressed display device is disclosed in, for example, Japanese Patent Application Laid-Open No. 4-265931, and its structure is shown in FIG. As shown, the plasma addressed display device has a flat panel structure including a display cell 1, a plasma cell 2, and a common intermediate sheet 3 interposed therebetween. The intermediate sheet 3 is made of an extremely thin plate glass or the like and is called a micro sheet. The plasma cell 2 is composed of a lower glass substrate 4 bonded to the intermediate sheet 3,
A dischargeable gas is sealed in the gap between the two. A stripe-shaped discharge electrode is formed on the inner surface of the lower glass substrate 4. These discharge electrodes function as an anode electrode A and a cathode electrode K. Since the discharge electrodes can be printed on the flat glass substrate 4 by a screen printing method or the like, productivity and workability are excellent. A partition 7 is formed so as to partition the anode electrode A and the cathode electrode K one by one, and a space filled with a dischargeable gas is divided to form a discharge channel 5. This partition wall 7 can also be formed by a screen printing method, and the top portion is in contact with one surface side of the intermediate sheet 3. Discharge channel 5 surrounded by a pair of partition walls 7
Inside, a plasma discharge is generated between the anode electrode A and the cathode electrode K. The intermediate sheet 3 and the lower glass substrate 4 are bonded to each other by a glass frit or the like.

On the other hand, the display cell 1 is configured using a transparent upper glass substrate 8. The glass substrate 8 is bonded to the other surface of the intermediate sheet 3 with a sealing material or the like via a predetermined gap, and a liquid crystal 9 as an electro-optical material is sealed in the gap. A signal electrode Y is formed on the inner surface of the upper glass substrate 8. Matrix pixels are formed at the intersections of the signal electrodes Y and the discharge channels 5. The color filter 1 is provided on the inner surface of the glass substrate 8.
3 is also provided, and for example, RGB three primary colors are assigned to each pixel. The flat panel having such a configuration is of a transmission type, for example, in which the plasma cell 2 is located on the incident side and the display cell 1 is located on the emitting side. A backlight 12 is attached to the plasma cell 2 side.

In the plasma address display device having such a configuration, a row-shaped discharge channel 5 in which plasma discharge is performed is switched in a line-sequential manner and scanned, and an image is applied to a column-shaped signal electrode Y on the display cell 1 side in synchronization with the scanning. Display driving is performed by applying a signal. When a plasma discharge is generated in the discharge channel 5, the inside becomes almost uniformly at the anode potential, and pixel selection is performed for each row. That is, one discharge channel 5 corresponds to one scanning line and functions as a sampling switch. When an image signal is applied to each signal electrode in a state where the plasma sampling switch is turned on, sampling is performed and lighting or extinguishing of the pixel can be controlled. Even after the plasma sampling switch is turned off, the image signal is held in the pixel as it is. The display cell 1 performs image display by modulating incident light from the backlight 12 into outgoing light in accordance with an image signal.

FIG. 7 is a schematic diagram showing only two pixels cut out. In this figure, two signal electrodes Y1 and Y2 and one cathode electrode K1 are provided for easy understanding.
And only one discharge channel 5 including one anode electrode A1 is shown. Each pixel 11 has a laminated structure including signal electrodes Y1, Y2, liquid crystal 9, intermediate sheet 3, and discharge channel 5. Discharge channel 5
Is substantially connected to the anode potential during the plasma discharge. When an image signal is applied to each of the signal electrodes Y1 and Y2 in this state, charges are injected into the liquid crystal 9 and the intermediate sheet 3. On the other hand, when the plasma discharge is completed, the discharge channel 5 returns to an insulating state and becomes a floating potential.
It is held at 1. A so-called sampling hold operation is performed. Therefore, the discharge channel 5 is connected to the individual pixels 11
Since they function as individual sampling switching elements provided in the switching symbol S1, they are schematically represented using switching symbols S1. On the other hand, the liquid crystal 9 and the intermediate sheet 3 held between the signal electrodes Y1, Y2 and the discharge channel 5
Functions as a sampling capacitor. When the sampling switch S1 is turned on by line-sequential scanning, an image signal is written to the sampling capacitor, and each pixel is turned on or off according to the signal voltage level. Even after the sampling switch S1 is turned off, the signal voltage is held in the sampling capacitor, and the active matrix operation of the display device is performed.

[0006]

FIG. 8 shows an equivalent circuit obtained by further simplifying the structure shown in FIG. An image signal is applied to the display cell 1 from the signal circuit 21 via the plasma switch S. That is, in the plasma addressed display device, the discharge channel formed in the plasma cell corresponds to the plasma switch S. When the switch S of the line where the plasma discharge has occurred is turned on, a signal voltage required for driving the liquid crystal of the display cell 1 is applied.

FIG. 9A shows a waveform of a discharge voltage applied to a discharge channel. Generally, while maintaining the anode electrode at the ground potential, a negative voltage pulse is applied to the cathode electrode to generate a plasma discharge in the discharge channel. As shown in (B), during a normal operation, a discharge current immediately rises in response to a voltage pulse applied to the cathode electrode (hereinafter, a cathode pulse), and sufficient charged particles are generated in the discharge space of the channel. , The channel space becomes conductive. That is, the plasma switch S shown in FIG. 8 is normally turned on. However, when the discharge channel is in an abnormal state, the discharge current does not sufficiently rise with respect to the application of the cathode pulse as shown in FIG. In the worst case, no discharge occurs as shown in (D). In the irregular discharge state as described above, sufficient charged particles cannot be generated. This means a malfunction of the plasma switch S. When the irregular phenomenon occurs, the image signal is not normally written to the corresponding line, and the display quality deteriorates. Possible causes of irregular discharge include reduced purity of the gas sealed in the channel, contamination or deterioration of the electrode surface, and contamination of the discharge channel space. Is difficult. SUMMARY OF THE INVENTION It is an object of the present invention to suppress irregular discharge by taking measures on a circuit, thereby improving display quality.

[0008]

The following means have been taken in order to achieve the above-mentioned object of the present invention. That is, the present invention stacks a display cell having a column-shaped signal electrode and a plasma cell having a discharge channel having an anode electrode and a cathode electrode arranged in a row and intersecting each signal electrode and each discharge channel. A flat panel provided with pixels in the section, a scanning circuit for applying a predetermined voltage to the cathode electrode with reference to the anode electrode and sequentially discharging each discharge channel to select a pixel for each row, A signal circuit for sequentially supplying an image signal to the signal electrodes in a column and writing the image signal to pixels in a selected row. When a predetermined voltage required for discharge is applied to the electrode for a predetermined period required for discharge, a trigger voltage exceeding the predetermined voltage is supplied to the discharge channel only during the initial period of application and irregular discharge is performed. And wherein the suppressing. Specifically, the scanning circuit supplies a trigger voltage exceeding the predetermined voltage by 30 V to 150 V to the discharge channel for 5 μs or less. At this time, the scanning circuit supplies a difference between the predetermined voltage and the trigger voltage to the cathode electrode side. In some cases, the scanning circuit may supply a difference between the predetermined voltage and the trigger voltage to the anode electrode side.

According to the present invention, in the plasma addressed display device, in addition to the discharge voltage, for example, a trigger voltage of about 30 V to about 150 V with a length of 5 μs or less is provided at the beginning of the pulse voltage required for plasma discharge. The irregular discharge is suppressed by adding. In some cases, additional pulses required to suppress irregular discharge may be applied to the anode electrode instead of the cathode electrode at the same timing, the same magnitude, and the same time length, but with opposite polarity. By appropriately adjusting the voltage value and time length of the added pulse, irregular discharge can be suppressed without increasing the discharge current, and there is no adverse effect on the electrode life. Conversely, since the rise of the discharge is accelerated by the additional pulse, the application time of the discharge voltage can be shortened as compared with the related art.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic diagram showing a first embodiment of a plasma addressed display device according to the present invention.
As shown in FIG. 1A, the present plasma addressed display mainly includes a panel 0, and further includes a peripheral signal circuit 21, a scanning circuit 22, and a control circuit 23. The basic configuration of panel 0 is the same as the panel of the conventional plasma addressed display device shown in FIG. That is, the panel 0 is composed of a display cell that modulates incident light into outgoing light in accordance with an image signal and displays an image, and a plasma cell that is surface-bonded to the display cell and performs scanning. The plasma cell has discharge channels 5 arranged in rows, and discharges sequentially to scan display cells line-sequentially. Each discharge channel 5 has a pair of discharge electrodes, and is driven for discharge by the scanning circuit 22. One of the pair of discharge electrodes functions as a cathode electrode K, and the other functions as an anode electrode A. In this embodiment, the scanning circuit 22 scans the display cells by sequentially applying cathode pulses to the cathode electrodes K1 to Kn. On the other hand, the anode electrodes A1 to An are grounded to the reference potential. The display cell has signal electrodes Y1 to Ym arranged in a column, and a pixel 11 is formed at an intersection with each discharge channel 5. The signal circuit 21 applies an image signal to each of the signal electrodes Y1 to Ym in synchronization with the above-described line sequential scanning of the discharge channel 5, and modulates incident light for each pixel 11. The control circuit 23 controls the synchronization between the signal circuit 21 and the scanning circuit 22.

As a characteristic feature, when the scanning circuit 22 applies a predetermined voltage (discharge voltage) required for discharge to the cathode electrode K with respect to the anode electrode A for a predetermined period required for discharge, it is limited to the initial period of application. Thus, a trigger voltage exceeding the discharge voltage is supplied to the discharge channel 5 to suppress irregular discharge. More specifically, as shown in FIG.
A trigger voltage exceeding a discharge voltage of about V by 30 V to 150 V is applied to the discharge channel for 5 μs or less. The application voltage and application time of this trigger pulse are set so as to suppress irregular discharge and not to increase discharge current. As shown in (B), in the present embodiment, the anode electrode A side is fixed to the ground potential, and a negative voltage pulse (cathode pulse) is applied to each cathode electrode K. By adding a trigger pulse to the beginning of the cathode pulse, irregular discharge is prevented.

FIG. 2 shows a discharge current waveform B when irregular discharge occurs, and a discharge current waveform A when the irregular discharge is suppressed by a trigger pulse. As described above, in order to prevent irregular discharge, a trigger pulse as shown in FIG. 1B is added to the tip of the cathode pulse. In the plasma addressed display device, the width of the trigger pulse is 5 μs or less, and the difference from the discharge voltage is 30 to 1
About 50V is appropriate. The width, position, and voltage level of the added trigger pulse are optimized so as to obtain an ideal discharge current waveform. As shown in FIG. 2, when the width and voltage level of the trigger pulse are increased with respect to the channel where the irregular phenomenon occurs, the rising of the discharge current waveform indicated by B becomes faster, and finally, as shown by A. Then, the discharge current saturates according to the cathode voltage. This is the optimum state for suppressing irregular discharge.

As shown in FIG. 3, when the voltage value and time width of the trigger pulse are further increased, a large spike current is observed at the leading end of the discharge current as shown in waveform C. . In a plasma addressed display device, an increase in discharge current leads to a reduction in electrode life, and thus a state in which a spike current is generated is not preferable.

FIG. 4 is a waveform diagram schematically showing the relationship between the voltage waveform applied to the cathode electrode and the discharge current waveform flowing through the discharge channel. As shown in (A), in the conventional plasma addressed display device, almost one horizontal period (1
During H), a predetermined voltage (discharge voltage) required for discharge is applied to the cathode electrode in a negative polarity. As shown in (B), in response to the application of the discharge voltage to the cathode electrode, plasma discharge occurs, the discharge current gradually increases, and reaches a steady state in the latter half of 1H. Then, at the same time when the application of the discharge voltage to the cathode electrode is released, the discharge current stops flowing. When the irregular phenomenon occurs, the time T1 at which the discharge current rises is shifted to the latter half within 1H.

(C) shows a case where a pulse obtained by adding a trigger voltage to a normal discharge voltage is applied to the cathode electrode. As shown in (D), by applying the cathode pulse to which the trigger voltage is added, the irregular phenomenon is suppressed, and the discharge current rises quickly. The rise time T2 shifts forward within 1H. In the figure, the difference between T1 and T2 is represented by ΔT. In the state shown in (D), the discharge current flows extra by the amount of hatching, which is not preferable from the viewpoint of electrode life. That is, the life of the cathode electrode tends to be shorter as the discharge current is larger. Therefore, in the present invention, as shown in (E), by shortening the width of the cathode pulse by ΔT, the total amount of the discharge current can be made approximately equal to that of the related art. In other words, an excess discharge current can be prevented from flowing by moving forward the fall point of the cathode pulse by an amount corresponding to the earlier rise of the discharge current due to the application of the trigger pulse.

FIG. 5 is a schematic view showing a second embodiment of the plasma addressed display device according to the present invention. To facilitate understanding, parts corresponding to those in the first embodiment shown in FIG. 1 are denoted by corresponding reference numerals. As shown in (A),
Unlike the first embodiment, the anode electrodes A1 to An are not grounded, and their potentials are controlled by the scanning circuit 22. Specifically, as shown in (B), the cathode potential changes from the ground potential GND to the negative polarity side, and at the same time, the anode potential rises to the positive polarity side. This change in the anode potential has a time width of 5 μs or less and a voltage width of 150 μs.
V or less. This makes it possible to apply a trigger pulse to the tip of the cathode pulse. That is, contrary to the first embodiment, even when a positive trigger pulse is applied to the anode A side, the effect of suppressing irregular discharge can be obtained. The cathode pulse has a conventional waveform, and a trigger pulse having a positive polarity is applied to the anode electrode in synchronization with the cathode pulse. At this time, the added pulse may be applied to all the anode electrodes A1 to An in common, or may be applied to the anode electrode A one by one while scanning by the scanning circuit 22 in synchronization with the individual cathode electrodes K. You may.

[0017]

As described above, according to the present invention, irregular discharge can be suppressed by inserting a trigger pulse at the beginning of a cathode pulse in a plasma addressed display device. By stabilizing the rising of the discharge, the flicker of display is improved, and the image quality is improved. Since the trigger pulse has the effect of accelerating the rise of the discharge, the width of the cathode pulse can be shortened by that amount, thereby reducing the discharge current and contributing to prolonging the life of the electrode.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a first embodiment of a plasma addressed display device according to the present invention.

FIG. 2 is a waveform chart for explaining the operation of the first embodiment.

FIG. 3 is a waveform chart for explaining the operation of the first embodiment.

FIG. 4 is a waveform chart for explaining the operation of the first embodiment.

FIG. 5 is a schematic view showing a second embodiment of the plasma addressed display device according to the present invention.

FIG. 6 is a schematic sectional view showing an example of a conventional plasma addressed display device.

FIG. 7 is a schematic diagram of a conventional plasma addressed display device.

FIG. 8 is a simplified equivalent circuit diagram of a conventional plasma addressed display device.

FIG. 9 is a waveform chart for explaining the operation of the conventional plasma addressed display device.

[Explanation of symbols]

0 panel, 1 display cell, 2 plasma cell, 3 intermediate sheet, 5 discharge channel, 9
... Liquid crystal, 11 ... Pixel, 21 ... Signal circuit, 2
2 ... scanning circuit, A ... anode electrode, K ... cathode electrode

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 2H089 HA36 QA16 TA18 2H093 NA71 NC23 NC62 ND41 ND47 5C006 AF42 BB18 BC03 BC12 FA22 GA03 GA04 5C080 AA10 BB05 DD09 FF11 JJ02 JJ04 JJ06 5C094 AA03 AA03 EA03 CA43

Claims (8)

[Claims] A display cell having a signal electrode in a column and a plasma cell having a discharge channel arranged in a row and having an anode electrode and a cathode electrode are stacked to form an intersection of each signal electrode and each discharge channel. A scanning panel for applying a predetermined voltage to the cathode electrode based on the anode electrode to sequentially discharge each discharge channel and select a pixel for each row; A signal circuit for supplying an image signal to a signal electrode in a sequential column and writing the image signal to a pixel in a selected row, wherein the scanning circuit comprises a cathode electrode based on the anode electrode. When a predetermined voltage required for discharge is applied for a predetermined period required for discharge, a trigger voltage exceeding the predetermined voltage is supplied to the discharge channel only during the initial period of application, and irregular discharge occurs. A plasma addressed display device characterized by suppressing. 2. The plasma addressed display device according to claim 1, wherein the scanning circuit supplies a trigger voltage exceeding the predetermined voltage by 30 V to 150 V to a discharge channel for 5 μs or less. 3. The plasma addressed display device according to claim 1, wherein said scanning circuit supplies a difference between said predetermined voltage and said trigger voltage to a cathode electrode side. 4. The plasma addressed display device according to claim 1, wherein said scanning circuit supplies a difference between said predetermined voltage and said trigger voltage to an anode electrode side. 5. An intersection of each signal electrode and each discharge channel by stacking display cells having column-shaped signal electrodes and plasma cells having discharge channels arranged in rows and having an anode electrode and a cathode electrode. A scanning procedure for applying a predetermined voltage to the cathode electrode based on the anode electrode and sequentially discharging each discharge channel to select a pixel for each row, in order to drive a flat panel having pixels provided therein; And a writing procedure of supplying an image signal to the signal electrodes in a column sequentially and writing the image signal to the pixels in the selected row in accordance with the scanning procedure. When a predetermined voltage required for discharge is applied to the cathode electrode for a predetermined period required for discharge with reference to the reference voltage, a trigger voltage exceeding the predetermined voltage is applied to the discharge channel only in the initial period of application. The driving method of the plasma addressed display device characterized by supplying to suppress the irregular discharge. 6. The method according to claim 5, wherein in the scanning procedure, a trigger voltage exceeding the predetermined voltage by 30 V to 150 V is supplied to the discharge channel for 5 μs or less. 7. The driving method for a plasma addressed display device according to claim 5, wherein in the scanning procedure, a difference between the predetermined voltage and the trigger voltage is supplied to a cathode electrode side. 8. The method according to claim 5, wherein in the scanning procedure, a difference between the predetermined voltage and the trigger voltage is supplied to an anode electrode side.