JPH06251717A - Plasma discharging cell - Google Patents

Abstract

PURPOSE:To equalize and stabilize plasma discharging throughout the entire length of a stripe-shape plasma channel in a plasma discharging cell. CONSTITUTION:A plasma discharging cell 2 is provided with one substrate 7, a discharging electrode 8 stripe-patterned on the surface of the substrate, the other substrate 3 connected to the substrate 7 through a certain area of space 13, and a gas that can be ionized and is sealed in the space 13. A barrier rib 11 is formed along each discharging electrode 8, and the space 13 is divided by the barrier rib 11 to form a stripe-shape plasma channel. The discharging electrode 8 has a multilayer structure containing an internal conductive layer 9 and a surface resistance layer 10. The surface resistance layer 10 functions as a load resistance, and plasma discharging is equalized and stabilized by self-bias effect. An intermediate insulator layer can be interposed between the internal conductive layer 9 and the surface resistance layer 10. The surface resistance layer 10 is electrically connected to the internal conductive layer 9 through a contact hole provided on the intermediate insulator layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma discharge cell incorporated in a plasma addressed liquid crystal display device or the like. More specifically, it relates to an electrode structure of a plasma discharge cell.

[0002]

2. Description of the Related Art A plasma addressed liquid crystal display device is known in which a plasma discharge cell is used for line-sequential addressing of a liquid crystal cell for displaying. For example, something like this
Japanese Unexamined Patent Publication No. 1-217396 discloses a discharge cell having a stripe-shaped plasma channel formed by etching. Further, Japanese Patent Application Laid-Open No. 4-265931 discloses a discharge cell having a plasma channel formed by a screen printing method. In order to clarify the background of the present invention, the structure of a conventional plasma addressed liquid crystal display device will be briefly described with reference to FIG. This device has a flat panel structure including a liquid crystal cell 101, a discharge cell 102, and a common intermediate substrate 103 interposed therebetween. The discharge cell 102 is the lower glass substrate 10.
4 and is provided with a plurality of parallel channels or grooves 105 on its surface. The grooves 105 extend, for example, in the row direction of the matrix. Each groove 10
Reference numeral 5 is sealed by the intermediate substrate 103 and constitutes a striped space 106 which is individually separated. An ionizable gas is enclosed in the sealed space 106. The convex portion 107 that separates the grooves 105 adjacent to each other functions as a partition wall that divides the individual stripe-shaped spaces 106, and also functions as a gap spacer. A pair of discharge electrodes 108 and 109 which are parallel to each other are provided at the bottom of each channel groove 105. This discharge electrode pair functions as an anode A and a cathode K and ionizes the gas in the stripe-shaped space 106 to generate discharge plasma. The plasma channel serves as a row scanning unit.

On the other hand, the liquid crystal cell 101 comprises an upper transparent substrate 11
It is configured using 0. The transparent substrate 110 is arranged to face the intermediate substrate 103 with a predetermined gap, and a liquid crystal layer 111 is filled in the gap. A signal electrode D made of a transparent conductive film is formed on the inner surface of the transparent substrate 110. This signal electrode D has a stripe-shaped space 10
It is orthogonal to 6 and becomes a column signal unit. Matrix-like pixels are defined at the intersections of column signal units and row scanning units.

Next, a method of driving the display device shown in FIG. 6 will be briefly described with reference to FIG. The plasma addressed liquid crystal display device is connected to an external drive circuit. This drive circuit includes a signal circuit 201, a scanning circuit 202, and a control circuit 203.
It consists of and. The signal electrode D is provided in the signal circuit 201.
1 to Dm are connected via a buffer. On the other hand, cathode electrodes K1 to Kn are connected to the scanning circuit 202 via a buffer and a load resistor R. The anode electrodes A1 to An are commonly grounded. The cathode electrode is line-sequentially scanned by the scanning circuit 202, and the signal circuit 201 supplies an image signal to each signal electrode in synchronization with this. The control circuit 203 controls the synchronization of the signal circuit 201 and the scanning circuit 202. A plasma discharge region is formed along the selected cathode electrode to form the above-described row scanning unit. On the other hand, the signal electrode serves as a column driving unit. A pixel 204 is defined between both units.

An external load resistor R is connected to each cathode electrode. The load resistance R is for suppressing the variation of the discharge current flowing in each row scanning unit and ensuring the uniformity of the plasma discharge over the entire screen. That is,
When an excessive discharge current flows to a specific cathode electrode, a voltage drop occurs in the corresponding load resistor R according to the amount of current, and the effective applied voltage is suppressed.

[0006]

By the way, unlike the conventional plasma display panel in which dot-like discharge regions are formed for each pixel, in the above-mentioned display device in which the liquid crystal cells are addressed by the stripe-like plasma channels, A linear discharge region is formed between the anode and the cathode adjacent to each other for each row scanning unit. When the screen is enlarged, the span of each discharge area becomes considerably long. In this case, there arises a problem that the discharge is concentrated only in a part due to the voltage drop due to the resistance component of the discharge electrode itself and other causes, and becomes non-uniform along one row scanning unit. If the discharge becomes non-uniform, the uniformity of the display is lowered and the image quality is degraded. Conventionally, an external load resistor R has been connected to each cathode electrode. However, this load resistance R is for equalizing the variation of the plasma discharge between the row scanning units, and it is not possible to suppress the local concentration of the plasma discharge in each row scanning unit. Therefore, in order to generate stable plasma discharge over one scanning unit, it is necessary to supply a discharge current with a sufficient margin. As a result, various problems such as a reduction in display contrast due to unnecessary plasma emission, an increase in power consumption, and a deterioration in life have occurred. Like this
In the conventional discharge current compensation method for each scanning unit, when the discharge electrode span is extended, the plasma discharge distribution is likely to slightly change due to local electrode shape non-uniformity, voltage drop, or disturbance in the discharge space, Since there is no function of locally absorbing the fluctuation, there is a problem that adverse effects such as uneven brightness of each pixel cannot be avoided.

This point will be further described with reference to FIG. FIG. 8 shows an equivalent circuit for one scanning unit. The plasma channels provided along the discharge electrode pair of the anode A and the cathode K are innumerable micro discharge cells T1, T2, T
It can be regarded as a set of 3, T4, ..., Tm. A load resistor R is connected to each micro discharge cell, and an anode A
A constant drive voltage V is supplied between the cathode and the cathode K for a predetermined selection period. At the start of discharge, the drive voltage V is applied as a trigger to all the minute discharge cells T1, T2, ..., Tm. However, when there is a cell T1 having a lower discharge starting voltage than other cells, the discharge cell T1 first starts discharging and its discharge sustaining voltage drops. As a result, the discharge concentration in the discharge cell T1 is further accelerated, and the sustain voltage is further lowered. Then, the electrode surface of the discharge cell T1 is activated by sputtering and the discharge concentration increases. On the other hand, when the cell T1 starts to discharge first, the effective voltage VT decreases, so that the discharge of the remaining discharge cells T2, T3, T4, ..., Tm is hindered. As a result, the non-uniformity of discharge in the innumerable minute discharge cells T1 to Tm increases, which not only adversely affects the display quality, but also shortens the life due to local concentration of electrode spatter.

[0008]

In view of the above-mentioned problems of the conventional technique, the present invention provides a discharge electrode structure capable of ensuring the uniformity of plasma discharge in a discharge cell having a stripe-shaped plasma channel. With the goal.
The plasma discharge cell according to the present invention has, as basic components, one substrate, a discharge electrode patterned in a stripe pattern on its surface, and the other of the substrates joined to each other through a predetermined space. It is provided with a substrate and an ionizable gas sealed in the space. As a characteristic matter,
The discharge electrode has a laminated structure including an internal conductor layer and a surface resistor layer. Preferably, the discharge electrode includes an intermediate insulator layer interposed between the internal conductor layer and the surface resistor layer. The surface resistor layer is electrically connected to the internal conductor layer via a contact hole provided in the intermediate insulator layer.
These internal conductor layer, intermediate insulator layer and surface resistor layer are
For example, it is composed of a thick film printed and baked product. More preferably, barrier ribs are formed along the discharge electrodes so as to be aligned with the contact holes, and form barrier ribs that are interposed between both substrates and partition the inter-substrate space. The plasma discharge cell having such a configuration is incorporated in, for example, a plasma addressed liquid crystal display device. The plasma addressed liquid crystal display device has a flat panel structure in which a liquid crystal cell having column-shaped signal electrodes and filled with liquid crystal and a discharge cell having row-shaped discharge electrodes and filled with an ionizable gas are stacked on each other. There is.
However, the application range or application range of the plasma discharge cell according to the present invention is not limited to this.

[0009]

According to the present invention, the discharge electrode has a laminated structure including the internal conductor layer and the surface resistor layer. The inner conductor layer is made of a low resistance material and has a function of supplying a power supply voltage while suppressing loss as much as possible. On the other hand, the surface resistor layer directly transfers and receives electric charges for plasma discharge, and also acts as a load resistor to provide a so-called self-bias function. That is, it is possible to absorb a local variation in discharge current and enable uniform and stable plasma discharge over the entire length of the plasma channel. In particular, by interposing an intermediate insulator layer between the internal conductor layer and the surface resistor layer, it is controlled so that migration at the conductor-resistor interface is prevented and the resistance value of the surface resistor layer is made uniform. .

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic sectional view showing an embodiment in which a plasma discharge cell according to the present invention is incorporated in a plasma addressed liquid crystal display device. It shows a shape cut along the column direction, that is, the signal electrode direction. This device has a flat panel structure in which a liquid crystal cell 1, a plasma discharge cell 2 and an intermediate substrate 3 made of an extremely thin dielectric sheet interposed between the liquid crystal cell 1 and the plasma discharge cell 2 are laminated. The liquid crystal cell 1 is configured by using the upper glass substrate 4, and a plurality of signal electrodes D made of a transparent conductive film are formed in parallel with each other on the inner main surface thereof. The glass substrate 4 is adhered to the intermediate substrate 3 using a spacer 5 with a predetermined gap. A liquid crystal layer 6 is filled in the gap.

On the other hand, the plasma discharge cell 2 is constructed by using the lower glass substrate 7. Discharge electrodes 8 that extend in the row direction orthogonal to the signal electrodes D are formed on the inner main surface of the substrate 7. The plurality of striped discharge electrodes 8 are divided into an anode A and a cathode K which are adjacent to each other. The anode A and the cathode K are switched alternately depending on the driving method. The discharge electrode 8 has a laminated structure and includes an internal conductor layer 9 and a surface resistor layer 10. Further, barrier ribs 11 are provided along the discharge electrodes 8 in the row direction. The upper end of the barrier rib 11 is in contact with the intermediate substrate 3 and serves as a spacer. The substrate 7 is adhered to the intermediate substrate 3 via the sealing material 12. An airtightly sealed space 13 is formed between the two. The above-mentioned barrier rib 11 divides this space 13 into stripes and constitutes a partition wall. The divided stripe-shaped spaces 13 individually form a plasma channel that serves as a row scanning unit. An ionizable gas is enclosed in the sealed space 13. The gas species can be selected from, for example, helium, neon, argon or a mixed gas thereof.

FIG. 2 shows a laminated structure of the discharge electrode 8. The inner conductor layer 9 is made of a thick film printed and fired material. For example, after screen-printing a conductor paste such as Ni paste, 600 ° C
It is obtained by firing at a certain degree. The inner conductor layer 9 has a low resistance of, for example, about 30 mΩ □, and can supply a stable drive voltage over the entire length of the plasma channel. The surface resistor layer 10 that covers the inner conductor layer 9 is also made of a thick film printed and fired product. For example, it is obtained by screen-printing a resistance paste and then firing it. For example, 2
It has a thickness of about 0 μm and a high resistance of about 1 MΩ □.
The surface resistor layer 10 directly participates in the transfer of charged particles contained in the plasma and also functions as a load resistance of the discharge electrode 8. Unlike the conventional load resistance structure externally attached to each discharge electrode, the present invention incorporates a load resistance in the plasma discharge cell. By simply printing and firing the surface resistor layer 10 so as to cover the internal conductor layer 9, the internal load resistance can be introduced very easily. Further, as compared with a structure in which a load resistance is added in a plane, the reduction of the aperture ratio of the plasma discharge cell is very small, which is advantageous when applied to a plasma addressed liquid crystal display device which is a non-emissive display.
As a result of actually forming a discharge electrode having a laminated structure and comparing it with that of the conventional structure, it was confirmed that abnormal discharge was suppressed and it was effective in uniformizing the discharge.

FIG. 3 shows an equivalent circuit for one plasma channel. In the plasma discharge cell shown in FIG. 1, an anode A and a cathode K made up of a pair of discharge electrodes 8 shown in FIG. 2 are arranged in parallel in a stripe shape, and plasma channels are line by line via a voltage power source E. It is driven line-sequentially. Therefore, a stripe-shaped plasma discharge can be obtained, but in an equivalent circuit, it can be considered that countless minute discharge cells T1, T2, T3, T4, ..., Tm are connected in parallel between the anode A and the cathode K. it can. According to the present invention, the load resistance r is individually connected to each micro discharge cell.
The load resistance r is composed of the resistance component in the thickness direction of the surface resistor layer 10 shown in FIG. If an excessive current flows in a specific minute discharge cell, a voltage drop occurs in the corresponding load resistance r, and the amount of current is suppressed. Due to such a self-biasing effect, it is possible to absorb the non-uniformity of the current flowing in each micro discharge cell. Since the internal conductor layer 9 is covered with the surface resistor layer 10, the discharge current always flows through the individual micro discharge cells via the load resistance r. When an attempt is made to increase or decrease the discharge current in each micro discharge cell, the amount of voltage drop caused by the corresponding load resistance r also increases or decreases, and as a result, negative feedback is applied so that the discharge currents flowing in all the micro discharge cells are always constant. In this way, the surface resistor layer 10 has a function of reducing the change in the discharge state.

FIG. 4 is a schematic sectional view showing another embodiment of a plasma addressed liquid crystal display device incorporating a plasma discharge cell according to the present invention. Basically, it has the same structure as that of the embodiment shown in FIG. 1, and corresponding parts are given corresponding reference numerals to facilitate understanding. The difference is that the discharge electrode has a two-layer structure in the previous embodiment, whereas the discharge electrode has a three-layer structure in this embodiment. That is, as shown in the figure, the discharge electrode 8 is an intermediate insulator layer 15 interposed between the internal conductor layer 9 and the surface resistor layer 10.
Is included. The surface resistor layer 10 is provided with the internal conductor layer 9 through the contact hole 16 provided in the intermediate insulator layer 15.
Electrically connected to. Each of the internal conductor layer 9, the intermediate insulator layer 15, and the surface resistor layer 10 is made of a thick film printed and fired product. Further, barrier ribs 11 are formed along the discharge electrodes 9 so as to be aligned with the contact holes 16.

FIG. 5 is a schematic enlarged view showing the three-layer structure of the discharge electrode. When the discharge electrode having the two-layer structure shown in FIG. 2 is to be produced by the printing and firing process, migration occurs at the interface between the conductor and the resistor due to thermal diffusion during the high temperature heat treatment, and the resistance value of the resistor layer is significantly reduced to control In some cases it cannot be done. Therefore, the three-layer electrode structure shown in FIG. 5 was adopted. The intermediate insulator layer 15 is sandwiched between the internal conductor layer 9 and the surface resistor layer 10 to form three structures, thereby suppressing migration during high temperature firing. The electrical connection between the internal conductor layer 9 and the surface resistor layer 10 is made by the intermediate insulator layer 1.
5 through the contact hole 16 opened in the shape of an island. In the region of the contact hole 16, migration occurs and the resistance value decreases, but since this region is covered with the barrier ribs described above, it does not contribute to the actual discharge. It is the region of the surface resistor layer exposed to the outside of the barrier rib that actually contributes to the discharge, and since there is no migration in this portion, the resistance value is controlled as set. Therefore, discharging is performed through the load resistance controlled according to the set value, and the equivalent circuit shown in FIG. 3 can be realized. As a result, uniform discharge is obtained and the display quality is improved. The contact holes may be formed by printing an insulating paste such as glass paste using a screen printing mask in which dot-shaped openings are provided in advance.

[0016]

As described above, according to the present invention, the stripe-shaped discharge electrode has a laminated structure including the internal conductor layer and the surface resistor layer. As a result, uniform and stable plasma discharge can be achieved over the entire length of each plasma channel, display contrast is improved, power consumption can be reduced, and life can be improved. Further, since the internal conductor layer is simply covered with the surface resistor layer, the aperture ratio of the plasma discharge cell is not sacrificed, which is advantageous when applied to, for example, a plasma addressed liquid crystal display device. .

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a plasma addressed liquid crystal display device incorporating a plasma discharge cell according to the present invention.

FIG. 2 is a schematic view showing a laminated structure of discharge electrodes which is a main part of the embodiment shown in FIG.

3 is an equivalent circuit diagram of a plasma channel included in the plasma discharge cell shown in FIG.

FIG. 4 is a schematic cross-sectional view showing another embodiment of a plasma addressed liquid crystal display device incorporating a plasma discharge cell according to the present invention.

5 is a schematic view showing a laminated structure of discharge electrodes which is a main part of the embodiment shown in FIG.

FIG. 6 is a perspective view showing an example of a conventional plasma addressed liquid crystal display device.

FIG. 7 is a drive circuit diagram of the conventional example shown in FIG.

FIG. 8 is an equivalent circuit diagram for explaining a problem of a conventional plasma discharge cell.

[Explanation of symbols]

 1 Liquid Crystal Cell 2 Plasma Discharge Cell 3 Intermediate Substrate 4 Glass Substrate 6 Liquid Crystal Layer 7 Glass Substrate 8 Discharge Electrode 9 Inner Conductor Layer 10 Surface Resistor Layer 11 Barrier Rib 13 Space 15 Intermediate Insulator Layer 16 Contact Hole A Anode K Cathode D Signal Electrode

Claims (6)

[Claims] 1. A substrate, a discharge electrode patterned in a stripe pattern on the surface of the substrate, another substrate joined to the substrate through a predetermined space, and an ionizable ion sealed in the space. A plasma discharge cell including a gas, wherein the discharge electrode has a laminated structure including an internal conductor layer and a surface resistor layer. 2. The discharge electrode includes an intermediate insulator layer interposed between the internal conductor layer and the surface resistor layer, and the surface resistor layer is a contact provided on the intermediate insulator layer. The plasma discharge cell according to claim 1, wherein the plasma discharge cell is electrically connected to the internal conductor layer through a hole. 3. The plasma discharge cell according to claim 2, wherein each of the internal conductor layer, the intermediate insulator layer and the surface resistor layer is made of a thick film printed and fired product. 4. The barrier rib is formed along the discharge electrode so as to be aligned with the contact hole, and the barrier rib is interposed between both substrates to form a partition wall for partitioning the space. Plasma discharge cell. 5. A plasma addressed liquid crystal having a flat panel structure in which a liquid crystal cell having column-shaped signal electrodes and filled with liquid crystal and a discharge cell having row-shaped discharge electrodes and filled with an ionizable gas are overlapped with each other. In the display device, the discharge electrode has a laminated structure including an internal conductor layer and a surface resistor layer, and is a plasma addressed liquid crystal display device. 6. The discharge electrode includes an intermediate insulator layer interposed between the inner conductor layer and the surface resistor layer, and the surface resistor layer is a contact provided on the intermediate insulator layer. The plasma addressed liquid crystal display device according to claim 5, wherein the plasma addressed liquid crystal display device is electrically connected to the internal conductor layer through a hole.