KR20080069311A - Apparatus and method for sealing vacuum tip - Google Patents

Abstract

A method and an apparatus for sealing a vacuum tip are provided to minimize a remaining stress due to a difference in heat expansion coefficients by directly fusing the vacuum tip on a board. An apparatus for sealing a vacuum tip includes a pressure head(210) and a heater(220). The pressure head applies pressure on an upper end of the vacuum tip. The heater locally applies the heat on a lower junction position of the vacuum tip. The heater includes a high frequency heating member. A driving unit moves the pressure head and the heater in a vertical direction. An elastic pad(212) is included in the pressure head.

Description

Exhaust tip sealing device and method {APPARATUS AND METHOD FOR SEALING VACUUM TIP}

1 is a perspective view showing an example of a surface light source device.

2 is a cross-sectional view taken along the line X-X 'of FIG.

3 is a schematic view showing an exhaust tip bonded to a substrate.

4 is a schematic view showing the bonding of the exhaust tip and the substrate using the bonding member.

5 is a schematic view showing the bonding of the exhaust tip and the substrate according to the present invention.

6 is a flow chart showing an exhaust tip sealing process according to the present invention.

7 is a schematic view showing the exhaust tip bonding concept of the present invention.

8 is a cross-sectional view showing an exhaust tip sealing device according to the present invention.

FIG. 9 is a cross-sectional view of a heating part of the sealing apparatus of FIG. 8. FIG.

*** Explanation of symbols for the main parts of the drawing ***

200: sealing device 210: pressurized head

220: heating portion 230: connection portion

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust tip sealing apparatus and method, and more particularly, to a direct bonding method of an exhaust tip used in an exhaust process of a product having a discharge space such as a surface light source device and a sealing apparatus therefor.

The liquid crystal display displays an image by using electrical and optical characteristics of the liquid crystal. Liquid crystal displays have the advantages of being very small in volume and light in weight compared to cathode ray tubes (CRTs). As a result, they are widely used in portable computers, communication devices, liquid crystal television receivers, and aerospace industries. .

The liquid crystal display device includes a liquid crystal controller for controlling liquid crystal and a rear light source for supplying light to the liquid crystal. The liquid crystal controller includes a pixel electrode disposed on the first substrate, a common electrode disposed on the second substrate, and a liquid crystal interposed between the pixel electrode and the common electrode. The pixel electrode is formed in plural in correspondence with the resolution, and the common electrode is made of one and facing the pixel electrode. A thin film transistor (TFT) is connected to each pixel electrode to apply a pixel voltage having a different level, and a reference voltage of the same level is applied to the common electrode. The pixel electrode and the common electrode are made of a transparent material having conductivity.

Light supplied from the rear light source sequentially passes through the pixel electrode, the liquid crystal, and the common electrode. In this case, the display quality of the image passing through the liquid crystal largely depends on the luminance and luminance uniformity of the rear light source. In general, the higher the luminance and the uniformity of the luminance, the better the display quality.

Conventionally, the rear light source of the liquid crystal display is mainly used a cold cathode fluorescent lamp (CCFL) having a rod shape or a light emitting diode (LED) having a dot shape. Cold cathode ray tube lamp has the advantage of high brightness, long life, and very low heat generation compared to incandescent lamps. On the other hand, the light emitting diode has a high power consumption, but has an advantage of excellent brightness. However, cold cathode ray tube type lamps or light emitting diodes have poor brightness uniformity. Accordingly, a rear light source having a cold cathode ray tube lamp or a light emitting diode as a light source is an optical member such as a light guide panel (LGP), a diffusion member, a prism sheet, or the like to increase luminance uniformity. (optical member) is required. As a result, a liquid crystal display using a cold cathode ray tube lamp or a light emitting diode has a problem in that the volume and weight of the optical member are greatly increased.

As a back light source for a liquid crystal display, a flat fluorescent lamp (FFL) in the form of a flat plate has been proposed. The surface light source device includes a light source body in which a plurality of discharge channels are integrally formed, and discharge gas is injected into the discharge channel in a vacuum state. In order to inject the discharge gas, vacuum exhaust and gas injection inside the discharge space are required. For this purpose, the upper plate and the lower plate are bonded to each other, and an exhaust tip is attached using a frit-based bonding material, and the internal discharge space is vacuumed. The exhaust tip was then cut and sealed.

However, in the case of using the frit-based bonding member, a high level of residual stress is formed at the joint due to a difference in coefficient of thermal expansion with glass, which is a substrate, and the residual stress acts as a cause of cracking in subsequent processes. In addition, a high temperature thermal process for curing the bonding member such as a frit must be accompanied. During this thermal process, impurity gas, which is a binder component of the bonding member, is ejected to act as a cause of lowering the internal vacuum degree of the discharge space.

The surface light source device has to maintain an internal discharge state with a very high precision, but it is difficult to maintain a high precision discharge state in a conventional manufacturing process.

The present invention has been made under such a technical background, and provides a method of not using a dissimilar bonding member in forming an exhaust tip of a surface light source device.

It is another object of the present invention to provide a high speed automation device for exhaust tip joining or sealing.

The present invention relates to a method and a device for sealing an exhaust tip for connecting a vacuum pump line in order to vacuum the discharge space after sealing the upper substrate and the lower substrate in the manufacture of a planar surface light source device having an internal discharge space, After preparing a light source body in which the upper plate and the lower plate are sealed in a predetermined working temperature region, the exhaust tip is locally melted and bonded directly to the exhaust hole of the substrate.

Specifically, the present invention provides a sealing device for an exhaust tip including a pressurizing head for applying pressure to an upper end of the exhaust tip, and a heating unit for locally applying heat to a lower junction portion of the exhaust tip.

The heating unit may include a heater to directly heat the exhaust tip or indirectly by an external high frequency heating means.

A driving unit for moving the pressing head and the heating unit up and down may further be included, and may further include an elastic pad inside the pressing head.

The invention also provides an exhaust comprising locally heating a bottom joining portion of an exhaust tip, attaching the exhaust tip to a joining portion of a substrate, and bonding the exhaust tip with a substrate while applying pressure to the exhaust tip. Provides a method of sealing the tip.

According to the present invention, it is possible to minimize the high level of residual stress due to the difference in coefficient of thermal expansion in the high temperature process after the exhaust tip sealing by directly bonding to the substrate through the welding of the exhaust tip itself without using a heterogeneous bonding material such as frit. In addition, it is possible to fundamentally solve product defects caused by cracks around the exhaust tip. In addition, since no heterogeneous bonding member is used, a sealing process for curing the heterogeneous bonding member is not necessary, and gas generation by the bonding member is minimized in the high temperature process after the exhaust tip sealing, so that high vacuum pressure of the discharge space of the surface light source device can be achieved. I can keep it.

1 and 2 illustrate an example of a surface light source device 100 having a plurality of discharge channels. The surface light source device 100 includes a light source body 110 and electrode units 160 provided on outer surfaces of both edges of the light source body 110.

The light source body 110 includes a first substrate 112 and a second substrate 114 disposed to face each other at a predetermined interval. A plurality of partition walls 140 are disposed between the first substrate and the second substrate to partition the space between the first substrate and the second substrate into a plurality of discharge channels 120. The discharge channel 120 and the partition wall part 140 may be formed by, for example, molding the first substrate 112, or may be formed by molding a second substrate instead of the first substrate.

A sealing member 130 is disposed between the edges of the first substrate 112 and the second substrate 114 to isolate the discharge channels 120 from the outside. Alternatively, the first substrate and the second substrate may be sealed by direct fusion.

Discharge gas is injected into the discharge space 150 inside the discharge channel 120. Although not shown, a fluorescent layer and a protective layer may be further included in the discharge channel 120, and a reflective layer may be formed on any one of the first substrate and the second substrate.

In order to inject the discharge gas, an exhaust process and a gas injection process are required. For this purpose, for example, as illustrated in FIG. 3, an exhaust port 116 is formed on one side of the second substrate 114, and a vacuum pump line is provided here. Attach the exhaust tip 170 for connection.

Exhaust tip 117 is a cylindrical structure typically includes a stem portion 172 corresponding to the body and a flare portion 174 which is an extension portion corresponding to the junction portion, the flare portion is larger in diameter than the exhaust hole of the substrate Is formed. In general, the exhaust tip is bonded to the flare portion of the exhaust tip and around the exhaust hole of the substrate through the bonding member 180 (see FIG. 4).

On the other hand, in the present invention, as shown in FIG. 5 without the bonding member, the exhaust tip is directly bonded to the substrate, thereby preventing process problems related to the use of the heterogeneous bonding member and deterioration of product performance of the surface light source device.

Referring to FIG. 6, an exhaust tip bonding to sealing process according to the present invention is illustrated, and a substrate (or a light source body) for the exhaust process is preheated to a predetermined temperature and prepared (step S1). The substrate itself does not need to be fused but may be directly fused with the exhaust tip when heated to a predetermined temperature.

The exhaust tip to be bonded to the substrate locally heats only the flare corresponding to the bonding portion with the substrate (step S2). Local heating of the exhaust tip can be used in various ways as described below. The heating temperature of the flare portion is a temperature near the softening point of the exhaust tip, and can be heated to a temperature of, for example, about 700 ~ 1000 ℃ when rapid heating and pressure bonding.

The heated exhaust tip is attached to the portion of the substrate to be bonded (step S3). Then, while the bonding portion of the exhaust tip is locally heated, pressure is applied to the exhaust tip (step S4) to instantaneously bond with the substrate (step S5). Steps S3 to S5 are performed in a very short time, so in most cases, they will be performed in one process.

The flared portion of the locally heated exhaust tip is instantaneously fused to the exhaust hole portion of the substrate that is already preheated to maintain a very tight bond. By not using a heterogeneous joining member, it is possible to fundamentally solve the occurrence of defects such as cracks associated with the exhaust tip joining, and there is no need for an additional thermal process for curing the joining member.

FIG. 7 is a schematic view illustrating the exhaust tip sealing concept of the present invention, and a firm bonding between the exhaust tip and the substrate is performed in a short time by the local heating (H) of only the flare portion 174 of the exhaust tip and the pressurization (F) of the exhaust tip. Make it possible. To this end, the present invention proposes a sealing apparatus as shown in FIG.

The sealing device 200 includes an upper pressurizing head 210 and a lower heating part 220. The pressurizing head 210 is located at the upper end of the exhaust tip to apply pressure downward, and the elastic pad 212 may be embedded so as not to give an excessive impact on the exhaust tip during pressurization.

After the upper substrate and the lower substrate are bonded together, the flat light source body in which the sealing process is completed is heated up to a temperature range in which the exhaust tip is fused in the heating furnace, or at the same time, the exhaust tip is heated through the heating unit 220 of the sealing apparatus. Local heating. Thereafter, the exhaust tip is positioned at the bonding portion of the light source body (or the substrate) and pressurized from the pressure head 210 to complete the instant bonding. In order to automate the exhaust tip forming process by continuously performing such a series of processes, the pressurizing head 210 and the heating unit 220 may be moved up and down by one driving unit.

For example, after local heating, when the exhaust tip is attached and pressurized, the sealing device can be moved downward so that the exhaust tip touches the substrate surface, and after fusion is completed, the sealing device can be moved upwards to disengage from the exhaust tip. There will be. The identification number 230 of the figure corresponds to the connection for the simultaneous movement of the pressure head and the heating unit in this way.

In this way, if the local heating and pressurizing means and the vertical conveying device of the exhaust tip flare are constituted by one system, the exhaust tip can be formed on the substrate at high speed, so that the entire process can be shortened and mass production is possible.

In the present invention, the heating portion of the sealing device can incorporate a plurality of heaters 22, as shown in FIG. The shape of the heating portion is preferably a trumpet shape similar to the flare portion to facilitate heat transfer to the flare portion of the exhaust tip. On the other hand, the heating unit may be indirect heating such as induction heating or dielectric heating by an external high frequency generating means instead of the heater. In this case, the heating unit may correspond to a heating mold that finally delivers heat to the flare unit.

The exhaust tip sealing device and the sealing method of the present invention are suitable for manufacturing a large area surface light source device, and may be easily applied to other flat panel display devices.

In the above, it has been described with reference to preferred embodiments of the present invention, but those skilled in the art or those skilled in the art from the spirit and scope of the invention described in the claims to be described later Various modifications and variations can be made in the present invention without departing from the scope thereof.

According to the present invention, it is possible to minimize the high level of residual stress due to the difference in the coefficient of thermal expansion in the high temperature process after the exhaust tip sealing by directly bonding to the substrate through the welding of the exhaust tip itself without using a heterogeneous bonding member, and exhaust It can fundamentally solve product defects caused by cracks around the tip. In addition, a sealing process for curing the heterogeneous bonding member is not necessary, and gas generation by the bonding member is minimized in the high temperature process after the exhaust tip sealing, thereby maintaining a high vacuum pressure in the discharge space of the surface light source device. Such an exhaust tip bonding method may be effectively applied not only to surface light sources but also to various display products and other related fields requiring a vacuum therein during the manufacturing process.

Claims (10)

A pressurizing head that pressurizes the top of the exhaust tip, A heating part for locally applying heat to the bottom junction of the exhaust tip Sealing device of the exhaust tip. The sealing apparatus of the exhaust tip of Claim 1 in which the said heating part is a built-in heater. The sealing device of the exhaust tip according to claim 1, wherein the heating part comprises a high frequency heating means. The sealing device of the exhaust tip of claim 1, further comprising a driving unit for moving the pressurizing head and the heating unit up and down. The sealing device of claim 1, further comprising an elastic pad inside the pressing head. Locally heating the bottom junction of the exhaust tip, Attaching the exhaust tip to a junction of a substrate; Bonding to the substrate while applying pressure to the exhaust tip; How to seal the exhaust tip. 7. The method of claim 6, wherein the heating step heats to a temperature near the softening point of the exhaust tip. 7. The method of claim 6, wherein the exhaust tip is directly heated with a heater. The exhaust tip sealing method according to claim 6, wherein the exhaust tip is indirectly heated by high frequency heating. 7. The method of claim 6, further comprising preheating the substrate.

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