JP2006100044A - Flat surface display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flat surface display device which surely prevents an short circuit accident of wiring from occurring and can improve reliability, by regulating the sticking-out of a sealing member in sealing a back substrate and a front substrate. <P>SOLUTION: The flat surface display device makes a front substrate 2 having a large number of phosphor layers 12 and metal backs 14 on the inner side face to face with a back substrate 4 having a large number of electron emission elements 16 on the inner side face each other with a predetermined space, creates a vacuum atmosphere inside, and maintains the phosphor layers and the metal backs at potential than higher than those of the electron emission elements. The front substrate and the back substrate are sealed along peripheries with each other with a sealing member 5, and barrier plates 7A, 7B of a sticking-out prevention member for regulating the sticking-out of the sealing member are placed on at least one-end sides of the front substrate and the back substrate and on at least one of the inside and the outside of the sealing member. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a flat display device that displays an image by emitting electrons from, for example, an electron-emitting device provided on a back substrate and exciting and emitting a phosphor layer provided on the front substrate.

In recent years, as a flat display device having a vacuum envelope with a flat flat panel structure, as disclosed in [Patent Document 1] and [Patent Document 2], a field emission display (FED), a surface conduction type A display device (SED) provided with an electron-emitting device is known.
FEDs and SEDs have a vacuum envelope in which the front and back substrates, which are opposed to each other with a predetermined interval through a spacer, are joined to each other with rectangular frame-shaped side walls and the inside is evacuated. ing.

A phosphor layer of three colors and a metal back covering the phosphor layer are formed on the inner surface of the front substrate, and a large number of phosphor layers corresponding to each pixel of the phosphor layer as an electron emission source for exciting and emitting the phosphor layer on the inner surface of the rear substrate. An electron-emitting device is disposed. Further, in order to maintain a high vacuum inside the vacuum envelope, a getter film is formed on the inner surface of the front substrate.
A voltage several kV higher than the electron-emitting device is applied to the phosphor layer, and the electron beam emitted from each electron-emitting device is accelerated by this electric field. Then, the accelerated electron beam is applied to the corresponding phosphor layer, and the phosphor is excited to emit light to display a color image.

In manufacturing such a flat display device, a phosphor layer and a metal back covering the phosphor layer are formed on the inner surface of the front substrate in advance, and a large number of electron-emitting devices are disposed on the inner surface of the rear substrate. Glass is used to seal a rectangular frame-shaped side wall at the peripheral edge of the back substrate, and a plurality of spacers are sealed on the back substrate.
Then, a base layer made of, for example, a silver paste is applied over the entire upper surface of the side wall serving as a sealing surface in the rear substrate and the inner peripheral edge of the front substrate, and metal sealing is performed on each base layer. Indium (In) as a material is filled to form a continuous indium layer.
Next, the back substrate and the front substrate are heated through baking processing, getter film processing, and the like to melt or soften indium into a liquid state. Thereafter, the front substrate and the side wall are joined and pressurized with a predetermined pressure, and indium is further cooled and solidified. Finally, the front substrate and the side wall are sealed with a sealing layer obtained by fusing the indium layer and the underlayer.
Japanese Patent Laid-Open No. 10-326583 JP 2000-31642 A

The problem lies in the process of heating the back substrate and the front substrate with the side walls sealed to melt or soften indium into a liquid, and then bonding the front substrate and the side walls and pressurizing them with a predetermined pressure. In this pressurizing step, the back substrate with the side wall protruding upward is set as the lower side, and the front substrate with the phosphor layer and the metal back facing the back substrate is positioned above the back substrate.
Then, the front substrate is brought into contact with the back substrate through the side wall and pressed together. At this time, indium in a molten or softened state may protrude from between the side wall and the front substrate.

The protruding indium flows down to the rear substrate as it is, reaches the wiring connected to the electron-emitting device provided on the rear substrate, and there is a risk of causing a short circuit accident between the wirings. For this reason, it is necessary to ensure a wide width of the side wall so that the indium protrudes within the width of the side wall.
In this type of flat display device, it is desirable that the space other than the display area is as small as possible, that is, the frame portion located around the display area is as small as possible, and the side wall width and the sealing width are desirably as narrow as possible. Therefore, there is room for improving the current situation where the width of the side wall must be increased.

Further, in a state where the vacuum envelope is completed, a sealing layer in which an indium layer and a base layer are fused is interposed between the side wall sealed on the rear substrate and the front substrate. By regulating the thickness of the sealing layer within a predetermined size range, a predetermined interval between the back substrate and the front substrate can be set accurately. Therefore, it is very important to regulate the thickness of the sealing layer within a predetermined dimension range.
On the other hand, as described above, indium is subjected to pressure in a softened or melted state, and therefore, a difference in the thickness of the sealing layer is likely to occur due to insufficient pressurization. That is, it is impossible to set the thickness of the sealing layer to a predetermined dimension, the distance between the back substrate and the front substrate is not constant, and the reliability is lacking.

  The present invention has been made paying attention to the above circumstances, and the purpose of the present invention is to regulate the protrusion of the seal member when sealing the back substrate and the front substrate, and to ensure that a short circuit accident of the wiring occurs. It is an object of the present invention to provide a flat display device that can prevent and improve reliability.

  In order to achieve the above object, the present invention provides a flat panel display device having an envelope formed by facing a front substrate and a rear substrate facing each other at a predetermined interval. The front substrate and the rear substrate are sealed along the peripheral edge of each other. A protruding prevention member for restricting the protruding of the sealing member is provided on at least one side of the front substrate and the rear substrate and at least one of the inner side and the outer side of the sealing member.

  According to the present invention, it is possible to restrict the protrusion of the seal member, to reliably prevent the occurrence of a short circuit accident in the wiring, and to obtain an improvement in reliability.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, an SED will be described as an example of a flat display device according to an embodiment of the present invention.
As shown in FIGS. 1 to 3, the SED 1 includes a front substrate 2 and a rear substrate 4 each made of a glass plate having a rectangular shape of 1 to 2 mm, and these substrates are about 1.0 to 2 through spacers 8. They are placed facing each other with a gap of 0 mm.
The front substrate 2 and the back substrate 4 are hermetically sealed along a peripheral edge of each other via seal members 5 and protrusion preventing members (hereinafter referred to as barrier plates) 7A and 7B, which will be described later. A vacuum envelope 10 is configured.

As the sealing member 5, a side wall 6 filled via a low melting point glass in the rear substrate 4 which is a glass material formed in a rectangular frame shape, and sealing between the side wall 6 and the front substrate 2 is sealed. Layer 20.
Here, the barrier plates 7A and 7B are sealed to the back substrate 4 through a low-melting glass at a position which is doubled along the inside and outside of the seal member 5 and as close to the side surface of the side wall 6 as possible. Is done.
The barrier plates 7 </ b> A and 7 </ b> B are not necessarily limited to being provided double along the inner side and the outer side of the seal member 5, and may be either the inner side or the outer side of the seal member 5. And it is not limited to along the perimeter of the sealing member 5 formed in a rectangular frame shape, You may provide along the at least one side part of the front substrate 2 and the back substrate 4. FIG.

High strain point glass is used for the side walls 6 constituting the seal member 5, the barrier plates 7 A and 7 B, the spacers 8 and the plate glass for the front substrate 2 and the back substrate 4. The process of attaching the seal member 5 and the barrier plates 7A and 7B to the front substrate 2 and the rear substrate 4 will be described later.
A phosphor layer 12 for displaying an image is formed on the inner surface of the front substrate 2. The phosphor layer 12 is configured such that red, blue, and green phosphor layers R, G, and B and a light shielding layer 11 are arranged and the phosphor layer is covered with a metal back 14. The phosphor layers R, G, and B are formed in stripes or dots, and the metal back 14 is formed of a metal thin film such as aluminum.

On the inner surface of the back substrate 4, a number of surface conduction electron-emitting devices 16 that emit an electron beam for exciting and emitting the phosphor layers R, G, and B are provided. These electron-emitting devices 16 are arranged in a plurality of columns and a plurality of rows corresponding to each pixel, and are composed of a pair of device electrodes for applying a voltage to an electron-emitting unit (not shown).
On the inner surface of the rear substrate 4, a large number of wirings 18 for applying a driving voltage to the respective electron-emitting devices 16 are provided in a matrix shape, and the end portions are drawn out of the vacuum envelope 10. .
In particular, as shown in FIG. 4, the side wall 6 and the barrier plates 7A and 7B constituting the seal member 5 are disposed on the insulating layer 25, and are provided on the wiring 18 through the insulating layer 25. become. In other words, the wiring 18 is covered with the insulating layer 25 in the region where the side wall 6 and the barrier plates 7A and 7B are disposed.

The front substrate 2 and the rear substrate 4 are sealed together after degassing and firing in a vacuum atmosphere to form a vacuum envelope 10, but the entire inner surface of the front substrate 2 is sealed in a vacuum atmosphere prior to sealing. A getter film is formed so that a high vacuum can be maintained after panel formation.
In the SED 1 configured as described above, when displaying an image, a voltage is applied between the element electrodes of the electron-emitting element 16 via the wiring 18. Then, an electron beam is emitted from an electron emission portion of an arbitrary electron emission element 16, and the electron beam is accelerated by the anode voltage applied to the phosphor layer 12 to irradiate the phosphor layer. As a result, the desired phosphor layers R, G, and B are excited to emit light and display an image.

Next, a method for manufacturing the SED 1 will be described in detail.
First, the phosphor layer 12 is formed on the plate glass to be the front substrate 2. In this method, a plate glass having the same size as that of the front substrate 2 is prepared, and a phosphor layer stripe pattern is formed on the plate glass by a plotter machine. The plate glass on which the phosphor stripe pattern is formed and the plate glass for the front substrate are placed on a positioning jig and set on an exposure table, whereby the phosphor layer 12 is generated by exposure and development.
Subsequently, the electron-emitting device 16 is formed on the plate glass for the back substrate 4. In this case, a matrix-like conductive cathode layer is formed on the plate glass, and an insulating film of a silicon dioxide film is formed on the conductive cathode layer by, for example, a thermal oxidation method, a CVD method, or a sputtering method.

After that, a metal film for forming a gate electrode such as molybdenum or niobium is formed on the insulating film by, for example, sputtering or electron beam evaporation. Next, a resist pattern having a shape corresponding to the gate electrode to be formed is formed on the metal film by lithography. Using this resist pattern as a mask, the metal film is etched by wet etching or dry etching to form a gate electrode.
Next, the insulating film is etched by wet etching or dry etching using the resist pattern and the gate electrode as a mask to form a cavity. Then, after removing the resist pattern, a peeling layer made of, for example, aluminum or nickel is formed on the gate electrode by performing electron beam evaporation from a direction inclined by a predetermined angle with respect to the surface of the back substrate 12.

Thereafter, for example, molybdenum is vapor-deposited as a cathode forming material by an electron beam vapor deposition method from a direction perpendicular to the surface of the back substrate 12. Thereby, the electron-emitting device 16 is formed inside each cavity. Subsequently, the release layer is removed together with the metal film formed thereon by a lift-off method.
A barrier plate 7 which is a protrusion preventing member between the peripheral edge of the back substrate 4 on which the electron-emitting device 16 is formed and the rectangular frame-shaped side wall 6 constituting the seal member 5 and inside and outside of the side wall 6, Seal together with low melting glass in the atmosphere. At the same time, the plurality of spacers 8 are sealed on the back substrate 4 with low-melting glass in the atmosphere.
Then, the back substrate 4 and the front substrate 2 are sealed to each other through the side wall 6. In this case, as shown in FIG. 4 again, the wiring 18 provided on the back substrate 4 is particularly covered with the insulating layer 25 in the region where the side wall 6 and the barrier plate 7 are disposed. The side wall 6 and the barrier plate 7 are bonded and fixed to each other through an adhesive such as low melting point glass.

The barrier plates 7A and 7B provided on both sides of the side wall 6 are preferably positioned as close to the side wall 6 as possible because of their functional characteristics, but the side wall 6 and the barrier plates 7A and 7B are bonded to the insulating layer 25. Since it is inevitable that the adhesive to be fixed oozes out from the respective bonded portions to some extent, it is impossible to make close contact.
From this state, as shown in FIG. 5, a base layer 30 made of, for example, silver paste is formed on the entire periphery of the upper surface of the side wall 6 serving as a sealing surface in the back substrate 4 and the inner peripheral edge of the front substrate 2, respectively. It is formed by applying to a predetermined width. In the front substrate 2, this process is performed upside down from the state shown in FIG.

Subsequently, indium (In) as a metal sealing material is filled and applied on the underlayer 30 formed on the side wall 6 and the front substrate 2 respectively, and indium continuously extending over the entire circumference of the underlayer 30. Layer 35 is formed. The indium layer 35 is formed so that the width of the indium layer 35 is narrower than the width of the underlayer 30, and the both side edges of the indium layer 35 are applied with a predetermined gap from the both side edges of the underlayer 30. That is, it is necessary that the indium layer 35 does not protrude from the underlayer 30 in this state.
As the metal sealing material, it is desirable to use a low melting point metal material having a melting point of about 350 ° C. or less and excellent adhesion and bondability. Indium used in this embodiment has not only a low melting point of 156.7 ° C., but also has excellent characteristics such as low vapor pressure, soft and strong against impact, and does not become brittle even at low temperatures. Moreover, since it can be directly bonded to glass depending on conditions, it is a material suitable for the purpose of the present invention.

As the low melting point metal material, not only a simple substance of In as a main component but also a simple substance of Bi, Sn, or Ga or an alloy containing at least one of them can be used. For example, in an eutectic alloy of In97% -Ag3%, the melting point is further lowered to 141 ° C., and the mechanical strength can be increased.
The above-described underlayer 30 is made of a material having good wettability and airtightness with respect to the metal sealing material, that is, a material having high affinity for the metal sealing material. In addition to the silver paste described above, a metal paste such as gold, aluminum, nickel, cobalt, or copper can be used. In addition to the metal paste, a metal plating layer or vapor deposition film such as silver, gold, aluminum, nickel, cobalt, copper, or a glass material layer can be used as the base layer 30.

In addition, when indium is applied and filled on the underlayer 30, filling indium while applying ultrasonic waves improves the wettability of indium to the sealing surface or the underlayer 30, and indium is in a desired position. Can be filled. Then, it is possible to continuously fill the molten indium along the underlayer 30 and to form an indium layer 35 extending without break along the underlayer, and at the time of filling, a part of the indium is formed. The alloy layer can be formed by diffusing into the surface portion of the underlayer 30.
Further, when indium is coated and filled on the underlayer 30, an inert gas such as nitrogen (N2) gas or argon (Ar) gas containing a predetermined amount of oxygen is blown toward the nozzle tip from a gas supply source. You should work. By performing the filling step in the inert gas atmosphere, the indium can be prevented from aggregating indium, and indium can be filled in a substantially ideal state. Then, the time during which the indium layer 35 is exposed to the air is shortened, and the oxidation of the surface of the indium layer is delayed to suppress the formation of an oxide film or the like.

Next, with the front substrate 2 turned upside down, as shown in FIG. 5, the base layer 30 and the indium layer 35 provided along the peripheral edge portion are on the lower surface side, and the upper portion of the side wall 6 provided on the back substrate 4 is placed. Make them face each other. Then, the front substrate 2 and the back substrate 4 are heated to 200 ° C. in a vacuum atmosphere to bring the indium into a molten or softened state.
As shown in FIG. 6, the front substrate 2 is lowered vertically while maintaining a vacuum atmosphere, and the front substrate 2 is bonded to the side wall 6 and the barrier plates 7A and 7B, and pressed together with a predetermined pressure. The front substrate 2 is hermetically filled with a side wall 6 provided on the rear substrate 4 via a sealing layer 40 that is a double structure of the base layer 30 and the indium layer 35.

At this time, a part of the pressurized molten indium may flow down the side surface of the side wall 6 as indicated by a two-dot chain line arrow in the figure, and a part of the molten indium should be cooled and solidified in the middle. However, the remaining part reaches the base end of the side wall 6 and further flows out onto the insulating layer 25.
However, here, barrier plates 7A and 7B as protrusion preventing members are provided along the inner side and the outer side of the side wall 6. Therefore, these barrier plates block the molten indium flowing out on the insulating layer 25 at that position. .
That is, even if molten indium flows out on the insulating layer 25, the molten indium does not flow out from the barrier plates 7A and 7B onto the external insulating layer 25. Therefore, it is possible to completely and reliably prevent the occurrence of an accident in which the wirings 18 exposed to the outside of the insulating layer 25 are short-circuited with molten indium, thereby improving the reliability.

Note that the melted indium has a low viscosity, so that it does not necessarily flow down the side surface of the side wall 6 but also leaches out from the sealing layer 40 formed between the side wall 6 and the front substrate 2 to the periphery. Conceivable. In this case, the molten indium tends to flow to the display area side or the outside of the front substrate 2.
However, barrier plates 7A and 7B as protrusion preventing members are arranged inside and outside the sealing layer 40, and the pressurizing process is performed in a vacuum atmosphere. Therefore, the end portions of the barrier plates 7A and 7B are attached to the front substrate 2. Contact closely. Therefore, the molten indium is prevented from flowing out to the outside by the barrier plates 7A and 7B, and does not flow out to the display area or the outside of the front substrate 2, and the same improvement in reliability can be obtained.

The barrier plates 7A and 7B as the protrusion preventing members also function as height regulating members. As described above, indium filled along the upper surface of the side wall 6 and the periphery of the front substrate 2 is melted or softened while being heated. In any case, the base layer 30 is filled with a very soft state, and the back substrate 4 and the front substrate 2 are pressed through the side wall 6.
The pressing force at this time is set to a predetermined pressure, but the pressurizing state varies depending on the state of indium. In other words, due to the characteristics of indium, overpressurization is likely to occur, and if it is left as it is, there will be a slight difference in the thickness of the completed sealing layer, resulting in a quality problem.
However, the barrier plate 7A. By setting the accuracy of the height dimension of 7B high (on the order of 10 μm), the front substrate 2 comes into contact with the upper end portions of the barrier plates 7A and 7B when the pressure is constant, and the thickness of the sealing layer 40 is increased. It can be set accurately and consistently. Even if the pressure is excessively applied, the barrier plates 7A and 7B receive the pressure and do not receive the sealing layer 40. Therefore, the sealing layer is not crushed and the thickness is stabilized.

After such a process, indium is removed and solidified. Thereby, the back substrate 4 provided with the side wall 6 and the front substrate 2 are sealed by the sealing layer 40 in which the indium layer 35 and the base layer 30 are fused, and the vacuum envelope 10 is formed.
In the above-described embodiment, the field emission type electron emission element is used as the electron emission element. However, the present invention is not limited to this, and other electron emission such as a pn type cold cathode element or a surface conduction type electron emission element. An element may be used. The present invention is also applicable to the manufacture of other image display devices such as a plasma display panel (PDP) and electroluminescence (EL).
Further, the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above-described embodiments. For example, you may delete some components from all the components shown by embodiment mentioned above.

The external appearance perspective view which shows the vacuum envelope of SED based on embodiment of this invention. The cross-sectional perspective view which cut | disconnected the vacuum envelope of FIG. 1 based on the same embodiment along line II-II. The partial expanded sectional view which expands and shows the cross section of FIG. 2 based on the embodiment partially. The partial top view which made the back substrate peripheral part the cross section based on the embodiment in the cross section. The figure explaining the sealing process of the back substrate and front substrate based on the embodiment. The figure explaining the sealing process of a back substrate and a front substrate following FIG. 5 based on the embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 12 ... Phosphor layer, 14 ... Metal back, 2 ... Front substrate, 16 ... Electron emission element, 4 ... Back substrate, 5 ... Seal member, 7A, 7B ... Barrier plate (extrusion prevention member), 18 ... Wiring, 25 ... Insulating layer, 6 ... sidewall, 35 ... indium layer (metal sealing material).

Claims (3)

In a flat display device having an envelope formed by facing a front substrate and a rear substrate at a predetermined interval,
The front substrate and the rear substrate are hermetically sealed through a seal member along the peripheral edge of each other,
A flat display device, wherein a protrusion preventing member for restricting protrusion of the seal member is provided on at least one side of the front substrate and the rear substrate and at least one of the inside and the outside of the seal member.   2. The flat display device according to claim 1, wherein the protrusion preventing member has a function as a height regulating member for setting the front substrate and the rear substrate at a predetermined interval. The back substrate is provided with wiring connected to the electron-emitting device,
This wiring is covered with an insulating layer in the region where the sealing member and the protrusion preventing member are disposed,
The sealing member includes a side wall made of a glass material provided on the rear substrate, and is softened or melted in a state of being filled and heated between the side wall and the front substrate, and is cooled and solidified in the side wall and the front substrate. 3. A flat display device according to claim 1, wherein the flat display device comprises a metal sealing material that seals between the two.

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