JP2000347164A - Channel substrate for plasma addressed liquid crystal panel and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent voltage necessary for generating plasma from being elevated due to lowering of helium pressure in channels caused by penetration of helium in a channel substrate in the plasma addressed liquid crystal(PALC). SOLUTION: In this channel substrate, in the case of using a channel surface of a glass substrate with helium as a PALC panel, sufficient partial pressure due to helium, which is an ionizable gas, is added to the channel surface of the glass substrate 4 so as to make helium be consumed from the channel with much lower rate than the case in which the helium pressure is not added to the channel surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to a mechanism for maintaining helium pressure in a plasma addressed liquid crystal (PALC) panel, and more particularly to a mechanism for maintaining such pressure.
The present invention relates to a channel substrate for an LC panel and a method of manufacturing the same.

[0002]

2. Description of the Related Art U.S. Pat. No. 5,077,553 (corresponding to Japanese Patent No. 2,601,713) describes an apparatus for addressing data storage elements. FIG. 2 shows a cross section of a PALC display panel in which the apparatus disclosed in U.S. Pat. No. 5,077,553 is actually implemented. Note that, for the sake of clarity, hatched lines indicating cross sections are omitted.

[0003] The PALC display panel shown in FIG. 2 includes, in order from the bottom, a polarizer 2, a glass channel member (also called a channel substrate or a glass substrate) 4, and a glass cover sheet (generally a microsheet). 6), an electro-optic material layer 10, an array of parallel and transparent data drive electrodes 12 (only one data drive electrode indicated by 12 is visible in FIG. 2), and data drive An upper substrate 14 for supporting electrodes and an upper polarizer 16 are provided.
When the PALC display panel is a color display panel, the panel includes a color filter (not shown) between the electro-optic material layer 10 and the upper substrate 14. This PAL
The C display panel may include a layer for improving a viewing angle or a layer for another purpose. The channel member 4 is typically made of glass, and has a number of parallel plasma channels 20 formed on an upper main surface thereof. Multiple channels 2
Numerals 0 are separated by ribs 22 and are filled with an ionizable gas such as helium. Anode 24 and cathode 2
6 are provided for each of the channels 20. The anode and the cathode are channel electrodes. For example, the voltage between the electrodes can be varied by changing the voltage of the cathode by using a channel electrode driver and setting the anode to the ground voltage. Channel 20
Is perpendicular to the data drive electrodes 12 (when viewed perpendicular to the panel) and the data drive electrodes 12
The areas that intersect zero form individual panel elements 28. Each panel element 28 can be considered to include the electro-optic material layer 10, the upper polarizer 16, and the lower polarizer 2. The area of the upper surface of the display panel that bounds the panel elements 28 constitutes a single pixel 30 of the display panel. Reference numeral 32 indicates the viewpoint of the observer.

When a reference potential is applied to the anode 24 in one channel 20 and a suitable, more negative voltage is applied to the cathode 26 in this channel, the gas in that channel creates a plasma which The plasma forms a conductive path to the reference potential source on the lower surface of the glass cover sheet 6.
If the data drive electrode 12 is at the reference potential, the data drive electrode 12
Has no substantial electric field, and the panel element 28 can be considered to be off. Conversely, if the potential of the data driving electrode 12 is substantially different from the reference potential, a substantial electric field is generated in the volume element of the electro-optic material layer 10, and the panel element 28 can be considered to be on.

In the following description, although not limiting the gist of the present invention, the lower polarizer 2 is a linear polarizer, and its polarization plane is arbitrarily set at 0 degree with respect to a reference plane. It is assumed that the upper polarizer 16 is a linear polarizer having a 90-degree polarization plane. The material of the electro-optic material layer 10 also rotates the plane of polarization of linearly polarized light passing therethrough by an angle that is a function of the electric field of the electro-optic material. When the panel element is off, the rotation angle is 90 degrees,
When the panel element is on, the rotation angle is 0 degrees.

The panel is illuminated from below by a broad light source 34 which emits unpolarized white light. In order to uniformly illuminate the panel, a back glass diffuser (ground glass) 18 having a scattering surface may be placed between the light source 34 and the panel. A predetermined panel element 2 from the light source 34
8 is linearly polarized at 0 degrees by the lower polarizer 2, passes through the channel member 4, the channel 20, the cover sheet 6, and the volume element of the electro-optical material in order, and passes through the upper polarizer 16 and the observation element. Head to person 32. If the panel element is off, the plane of polarization of linearly polarized light passing through the volume element of the electro-optic material rotates 90 degrees, so the plane of polarization of light incident on the upper polarizer 16 is 90 degrees. This light passes through the upper polarizer 16 and illuminates the pixels. On the other hand, if the panel element is on, the plane of polarization of the linearly polarized light does not change when passing through the volume element of the liquid crystal material. Since the polarization plane of the incident light of the upper polarizer 16 is 0 degree,
This light is blocked by the upper polarizer 16 and the pixels are dark. If the electric field in the liquid crystal material is between the values associated with turning off and on the panel element 28, this light will pass through the upper polarizer 16, but its brightness will be determined by the electric field and will be gray scale (halftone). Can be displayed.

In the implementation of the PALC display panel, the channel member 4 is etched near a region where a channel is to be formed, and a base (plateau) 36 is provided. The channel 20 is formed in the base. The cover sheet 6 is fixed (closed) to the channel member 4 by endless frit beads 38 in a lavet (tongue) 40 extending near the periphery of the base. An upper substrate assembly including the upper substrate 14 and the data driving electrodes 12 supported thereon;
It is attached to the channel member 4 by the bonding beads 42.

[0008]

When a plasma is present in a channel, charged molecules in the channel are accelerated with high levels of kinetic energy. Some of these molecules collide with the channel surface (the surface of the channel substrate and the surface of the cover sheet secured to the channel), causing the channel surface to heat up. The channel substrate is a glass substrate on which a channel is formed, and the channel substrate assembly is a combination of a channel substrate and a cover sheet attached to the channel substrate.

Helium penetration rate (ratio) into glass
Is known to be very dependent on the temperature of the glass. For example, helium 15 vs. glass of the type conventionally used in assembling channel surfaces of PALC panels.
The penetration rate at 0 ° C. is about 100 at about 18 ° C.
It is twice. Thus, when the plasma is activated and the channel surface of the channel substrate is heated, helium rapidly penetrates the hot channel surface of the channel substrate, and after the plasma is removed, most of the channel substrate is cooled. Go.

When the plasma is removed, the heat on the channel surface of the channel substrate cools down, and some of the helium that has already penetrated the channel substrate returns to the channel. As the channel surface of the channel substrate cools down quickly, the helium penetration rate back into the channel from the majority of the channel substrate when the plasma is turned off will cause the plasma to penetrate the majority of the channel substrate during operation. Very low speed. Thus, helium is trapped on the channel surface. That is, helium in the channel is consumed. As enough helium is trapped on the channel surface, reducing the pressure of helium remaining in the channel by a factor of about two, the voltage required to form a plasma increases.
If the voltage rises to a range beyond the capability of the drive circuit,
The PALC panel cannot operate.

Therefore, an object of the present invention is to reduce the pressure of helium in a channel during the operation of a PALC panel by the further penetration of helium into the channel substrate, thereby depleting the helium in the channel and thereby forming a plasma. To provide a channel substrate for a PALC panel and a method of manufacturing the same, which prevent a voltage required for the panel from rising.

[0012]

According to a first aspect of the present invention, a channel substrate for a PALC panel according to the present invention comprises a glass substrate 4 in which channels 20 are formed; Sufficient partial pressure is applied to the channel surface of the glass substrate 4; when using the channel surface of the glass substrate 4 with helium as a plasma-addressed liquid crystal panel, it is much more evident than without helium pressure on the channel surface. The helium is depleted from the channel 20 at a low rate.

According to a second aspect of the present invention, the P
Channel substrate assembly for ALC panel is channel 2
A glass substrate 4 on which a "0" is formed; and a glass cover sheet 6 attached to the glass substrate.
A sufficient partial pressure of helium, an ionizable gas, is applied to the channel surface of the channel substrate assembly; helium pressure is applied to the channel surface when the channel surface of the glass substrate is used together with helium as a plasma addressed liquid crystal panel. Helium is depleted from the channel at a much lower rate than without.

According to a third aspect of the present invention, the P
The channel substrate for the ALC panel includes a glass substrate 4 in which a channel 20 is formed; a coating 46 having a lower helium penetration rate than the glass substrate 4 and a higher melting point than the glass substrate 4 is provided on the surface of the glass substrate 4. The use of a coated channel substrate in a plasma addressed liquid crystal panel with helium, an ionizable gas, causes helium to be depleted from the channel at a much lower rate than when the substrate is not coated. Features.

According to a fourth aspect of the present invention, the P
The manufacturing method of the channel substrate for the ALC panel is as follows.
Providing a glass substrate 4 on which 0 is formed; applying pressure to the channel surface of the glass substrate with helium; thereafter, filling the channel 20 with helium and sealing the channel 20.

According to a fifth aspect of the present invention, there is provided:
A glass substrate 4 on which a channel 20 is formed;
A method of processing a channel substrate assembly for a plasma addressed liquid crystal panel comprising: a cover sheet 6 attached to a glass substrate over a glass substrate; heating the channel substrate assembly to increase the temperature; A partial pressure is created in the helium therein; it is characterized by a closed channel.

According to a sixth aspect of the present invention, a method of manufacturing a channel substrate for a plasma addressed liquid crystal panel according to the present invention comprises the steps of providing a glass substrate 4 having a channel 20 formed thereon; Coating 46
The material of the coating 46 is characterized by a lower helium penetration rate than the glass substrate and a higher melting point than the glass substrate.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. In the accompanying drawings, corresponding elements are denoted by the same reference numerals. In this specification, words indicating relative directions and positions such as up and down indicate directions and positions with respect to the drawings, and are not limited to absolute meanings. Thus, in this specification, the surface described as upper may, in certain embodiments of the present invention, correspond to the lower surface or may correspond to a vertical surface that is neither upper nor lower.

The rate at which helium penetrates into the glass from the space bounded by the surface of the glass depends not only on the temperature of the glass, but also on the partial pressure of helium in the glass, It also depends on the partial pressure of helium in the empty space.

According to the present invention, the channel surface of the PALC (display) panel is pre-pressed with helium. Therefore, the partial pressure of helium in most of the channel substrate 4 increases, and the difference between the partial pressure of helium in the channel and the partial pressure of helium in most of the channel members decreases, and the difference from the channel decreases. The rate of helium penetration into most of the channel members is reduced. Therefore, the consumption of helium in the channel is reduced.

At elevated temperatures and pressures, the channel surface can be pre-pressurized with helium by filling and sealing the panel with helium. conventionally,
The panel was filled with helium and sealed at a pressure in the range of about 100 to about 500 hectopascals and a temperature in the range of about 20 to 50 ° C. Increased pressure and temperature (200-9
Fill the panel with helium at 00 hectopascals (250-400 ° C.) and seal, allowing helium to penetrate the glass. Helium remaining in the channel after permeation has sufficient partial pressure for panel operation.

As an alternative to the above, before the channel is filled with helium and sealed, but after completing the high temperature processing required for the assembly of the channel substrate assembly, the substrate in a helium atmosphere is heated to Pressure can be pre-applied to the channel surface. In this case, the channel substrate can be heated to around 550 ° C. This temperature is near the softening point of the glass.

A third method places the channel substrate assembly (channel substrate 4 and cover sheet 6) under an RF (high frequency) helium plasma. Prior to the operation of filling and sealing the channel with helium, the channel substrate assembly is placed in a cavity, which contains helium. Here, an RF electric field suitable for ionizing helium is generated. By creating a plasma by this method, helium penetrates into the surface layer, but when the plasma is removed, helium is captured. When the channel substrate assembly is filled and sealed with helium, the temperature is low enough and the pressure is high so that the helium remains trapped in the glass.

Another method of avoiding the problem of helium penetration into glass is that the rate of helium penetration into the glass is sufficiently lower than the rate of helium penetration into glass of the type conventionally used in the manufacture of PALC display panels. In order to achieve this, a surface barrier (barrier) as a coating is provided on the glass, and the type of the glass is selected.

The glass conventionally used for assembling PALC display panels is typically borosilicate glass, such as the glass sold by Schott Glass under the name D263. Other glasses, such as alkali-free borosilicate glass sold by Schott Glass under the name AF45, are high-concentration barium oxide and aluminum oxide, suitable for assembling PALC display panels and in the required temperature range. , The helium penetration rate is significantly lower.

By performing vacuum plating with a material having a lower helium penetration rate and a higher melting point than borosilicate glass conventionally used for assembling a PALC display panel,
A suitable surface barrier (coating) is obtained.

FIG. 1 is a partial cross-sectional view of a preferred embodiment of a channel substrate for a PALC panel according to the present invention, which corresponds to the portion of the channel 20 in FIG.
Is the same as Before depositing the channel electrode, a barrier layer (coating) of the above material
46 is provided on the surface of the channel boundary of the channel substrate 4. By providing the barrier layer 46, the relative temperature of the channel surface of the substrate becomes lower than when the channel boundary is made of borosilicate glass. One material that has a lower helium penetration rate than borosilicate glass and a higher melting point than borosilicate glass is sapphire. Techniques for depositing a layer of sapphire on a glass surface are known.

Having described the preferred embodiment of the present invention,
Various modifications and changes are possible without departing from the spirit of the present invention.

[0029]

As described above, according to the present invention, PALC
As the helium further penetrates into the channel substrate during the operation of the panel and the pressure of helium in the channel decreases, it is possible to prevent the voltage required for plasma formation from increasing.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a preferred embodiment of a channel substrate for a PALC panel according to the present invention.

FIG. 2 is a partial cross-sectional view of a conventional PALC panel.

[Explanation of symbols]

 2 Lower polarizer 4 Channel member (channel substrate, glass substrate) 6 Glass cover sheet 10 Electro-optical material layer 12 Data drive electrode 14 Upper substrate 16 Upper polarizer 18 Back glass diffuser 20 Plasma channel 22 Rib 24 Anode 26 cathode 28 panel element 30 pixel 32 observer's viewpoint 34 light source 38 frit seal 46 barrier layer (coating)

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kevin J. Ilsicine 97007 Beaverton, Oregon United States 8650 Beaverton Southwest Moulder Drive 8650 (72) Inventor Thomas S. Bezack United States 97007 Beaverton South, Oregon West Stone Creek Drive 9755

Claims (6)

[Claims] 1. A glass substrate having a channel formed therein, wherein a sufficient partial pressure of helium, which is an ionizable gas, is applied to the channel surface of the glass substrate, and the channel surface of the glass substrate is plasma-coated with the helium. A channel substrate for a plasma-addressed liquid crystal panel, wherein when used as an address liquid crystal panel, the helium is consumed from the channel at a much lower rate than when no pressure is applied to the channel surface by helium. . 2. A channel substrate assembly for a plasma addressed liquid crystal panel, comprising: a glass substrate having a channel formed therein; and a glass cover sheet attached to the glass substrate, the helium being an ionizable gas. Is applied to the channel surface of the channel substrate assembly, and when the channel surface of the glass substrate is used as a plasma-addressed liquid crystal panel together with the helium, no pressure is applied to the channel surface by helium. A channel substrate assembly for a plasma addressed liquid crystal panel, wherein said helium is depleted from said channel at a much lower rate than said channel. 3. A channel substrate for a plasma addressed liquid crystal panel, comprising a glass substrate having a channel formed thereon, wherein the coating has a lower permeation rate for helium than the glass substrate and a higher melting point than the glass substrate. When the coated channel substrate is used for the plasma-addressed liquid crystal panel together with the ionizable gas helium, which is coated on the surface of the glass substrate, at a much lower rate than when the substrate is not coated. A channel substrate for a plasma addressed liquid crystal panel, wherein helium is consumed from the channel. 4. A plasma characterized by providing a glass substrate having a channel formed therein, applying pressure to the channel surface of the glass substrate with helium, and thereafter filling the channel with the helium and sealing the channel. -A method of manufacturing a channel substrate for an address liquid crystal panel. 5. A method for processing a channel substrate assembly for a plasma addressed liquid crystal panel, comprising: a glass substrate having a channel formed therein; and a cover sheet covering the channel and attached to the glass substrate, A method of processing a channel substrate assembly for a plasma addressed liquid crystal panel, comprising: heating a channel substrate assembly to increase a temperature; generating a partial pressure in helium in the channel of the glass substrate; and sealing the channel. 6. A method of manufacturing a channel substrate for a plasma addressed liquid crystal panel, comprising: providing a glass substrate having a channel formed thereon; and forming a coating on a surface of the glass substrate. A method of manufacturing a channel substrate for a plasma addressed liquid crystal panel, wherein the material has a lower helium penetration rate than the glass substrate and a higher melting point than the glass substrate.