Method for fabricating a window member of the display device of a portable terminal

A method for fabricating a window member for a display device of a portable terminal includes: fabricating a high-hardness sheet to be attached to a surface of the window member (‘sheet fabrication step’), fabricating a body of the window member with a high-polymer synthetic resin (‘body fabrication step’), and attaching the high-hardness sheet to an outer surface of the body (‘attaching step’), in which the outer surface of the body is formed to have a curved surface in the body fabrication step.

CLAIM OF PRIORITY

This application claims the benefit under 35 U.S.C. §119(a) of a Korean Patent Application filed in the Korean Intellectual Property Office on Jun. 28, 2011 and assigned Serial No. 10-2011-0063204, the entire disclosure of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display device of a portable terminal, and more particularly, to a method of fabricating a window member of the display device.

2. Description of the Related Art

Generally, a portable terminal such as a mobile communication terminal and other portable multimedia devices includes a display unit and a transparent window member mounted on the display unit for protection.

Using a display screen, a portable terminal user performs various operations through an input device such as a separate keypad, a track pad, or the like. However, as functions, such as Internet access, multimedia reproduction, and so forth, can be executed through a mobile communication terminal, a display device equipped with a touch screen has become a popular choice for many users.

As a user manipulates the touch screen for operation, a long-term use of the portable terminal can cause damage and scratches on the surface of a window member, thus degrading the quality of the touch screen. Accordingly, much efforts have been made to prevent a window member of the touch screen from being damaged.

A window member of the touch screen is typically fabricated using an acryl sheet, a high-polymer film, etc., or injection molding using acryl. However, the window member fabricated using such high-polymer synthetic resin has low surface quality or clarity, and particularly, low surface durability. These factors are drawbacks and limitations in operation.

To reinforce the durability (i.e., hardness) of the surface of the window member fabricated using a high-polymer synthetic resin material, a coating may be applied thereto, but the coating of the window member surface may not guarantee the surface uniformity of the window member. When a non-uniform surface is applied to the display device, a distortion of the screen occurs.

Alternatively, to prevent the surface of the window member from being damaged, the window member may be fabricated using a tempered glass. In spite of excellent surface quality, transmissivity, clarity, etc., the tempered glass requires repetitive processes until it is made into a window member of desired standard and quality, thus resulting in a high fabrication cost. Moreover, its yield is low due to generation of defective products caused by chips from the manufacture process.

As explained above, when the surface of the window member is implemented with a curved surface, it becomes more difficult to guarantee the surface quality of the window member fabricated using a synthetic resin material. Also, when the window member is fabricated using a tempered glass, its processing becomes more complicated, thereby increasing a fabrication cost or the like.

SUMMARY OF THE INVENTION

Accordingly, an aspect of the present invention is to provide a method for fabricating a window member having a curved surface for a portable terminal display capable of providing an excellent surface quality while maintaining a sufficient hardness.

Another aspect of the present invention is to provide a method for fabricating a window member having a curved surface which reduces a fabrication cost through a simplification of fabrication process while maintaining a sufficient hardness and an excellent surface quality.

According to another aspect of the present invention, a method for fabricating a window member for a display device of a portable terminal includes: fabricating a high-hardness sheet to be attached to a surface of the window member (‘sheet fabrication step’), fabricating a body of the window member with high-polymer synthetic resin (‘body fabrication step’), and coupling the high-hardness sheet to an outer surface of the body (‘attaching step’), in which the outer surface of the body is formed to have a curved surface in the body fabrication step.

According to yet another aspect of the present invention, a method for producing a window member for a portable terminal display device includes: providing a high-hardness sheet substantially defining a shape of the window member from a sheet material made of an organic/inorganic complex material or a glass material; fabricating a body of the window member having a curved shape with a high-polymer synthetic resin via an injection molding process; and coupling the high-hardness sheet to the fabricated body of the window member.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. For the purposes of clarity and simplicity, well-known functions and structures will not be described as they unnecessarily obscure the subject matter of the present invention.

FIG. 1is a flowchart of a method10for fabricating a window member of a portable terminal according to an embodiment of the present invention.

As shown, the window fabrication method10may include sheet fabrication step11for processing a high-hardness sheet (33shown inFIG. 4A) suitable for a window member to be fabricated from a sheet material, step13for fabricating a body of the window member, and step15for coupling the fabricated high-hardness sheet to the fabricated body of the window member.

Referring toFIGS. 4A through 5, a high-hardness sheet33is attached to an outer surface of the body31, and the body31has a curved surface. As such, when the window member30is mounted on a portable terminal, a side of the body31on an outer surface would yield a curved side shape.

Referring back toFIG. 1, the sheet fabrication step11involves fabricating a high-hardness sheet by processing the sheet material made of an organic/inorganic complex material or a glass material having a hardness of 9H or more with respect to pencil hardness and a thickness of 0.2 mm or less. The organic/inorganic complex material is a polyester-group high-polymer film of which both surfaces are coated by UV curing resin to which a silica nano-filler is added. Such a sheet material is fabricated to have a thickness of 0.2 mm or less, thus guaranteeing a hardness of 9H or more while minimizing strain stress during an attachment of the finished high-hardness sheet to the body of the window member or during a double injection of the finished high-hardness sheet.

To fabricate the high-hardness sheet suitable for the window member, a design of the high-hardness sheet at a desired standard is printed onto a sheet material made of an organic/inorganic complex material or a glass material, and then the sheet material is processed according to the printed design. The sheet material may be processed by using a lathe, more specifically, a Computerized Numerical Control (CNC) lathe. Here, the sheet metal process using the CNC lathe is preferably performed on conditions of a CNC lathe rotating speed of 40,000 rpm or more to 60,000 rpm or less, and a CNC lathe transferring speed of 400 mm/min or more to 600 mm/min or less. Prior to processing of the sheet material, a bezel or a manufacturer's symbol may be printed onto an edge portion of the high-hardness sheet to be fabricated.

If the bezel or the manufacturer's symbol is printed onto the high-hardness sheet, various structures may be formed on the body31of the window member30. A conventional window member is fabricated by using injection molding or processing tempered glass, and the bezel or the manufacturer's symbol is printed onto an inner side of the fabricated window member or attached in the form of a separate film. As a result, it is not possible to form a separate structure in the inner side of the conventional window member. Further, to couple the window member to a housing of the portable terminal, a both-sided tape or an adhesive is used in the past.

In the window member fabrication method according to the present invention, the high-hardness sheet is attached to an outer side of the body of the window member, and the bezel or the manufacturer's symbol may be printed onto the high-hardness sheet, such that various structures can be formed in the inner side of the body. Therefore, the window member can be assembled to a product such as a portable terminal, without using an adhesive material such as a both-sided tape as in the prior art.

The body fabrication step13involves fabricating a body31of the window member30with high-polymer synthetic resin, more specifically, polymethylmethacrylate (PMMA) resin or polycarbonate (PC) resin, preferably by using injection molding. The PMMA resin or PC resin, because of becoming transparent after cured, is suitable for the window member provided to the display device. Referring toFIG. 4, the body31substantially defines the shape of the window member30. The high-hardness sheet33finished in the sheet fabrication step11is attached to an outer surface of the body31. Here, the sheet fabrication step11and the body fabrication step13are performed through a separate process, and thus these steps do not need to be sequentially performed.

In an alternate embodiment, if the high-hardness sheet33can sufficiently endure heat and pressure during an injection molding process, the high-hardness sheet33can be preinstalled in the inner side of a mold51(seeFIG. 7) when fabricating of the body31, and thus can be attached to the body31simultaneously with molding of the body31through a double injection. In other words, although step15of attaching the high-hardness sheet33to the body31is separately shown inFIG. 1, the window member fabrication method10according to an embodiment shown inFIG. 1may simultaneously perform the body fabrication step13and the attaching step15through a double injection.

To attach the high-hardness sheet33to the body31, a roll lamination process may be used in lieu of the above double injection. That is, the high-hardness sheet33can be positioned on the outer surface of the body31and attached to the body31by pressurization with a roller43(seeFIG. 5). To perform the roll lamination process, an adhesive material is preferably disposed between the high-hardness sheet33and the body31. To this end, an Optical Clear Adhesive (OCA) film and an UV curing adhesive can be used to attach the high-hardness sheet33to the body31.

Referring toFIG. 2, to attach the high-hardness sheet33to the body31using the OCA film, the OCA film is attached to the sheet material before processed to the high-hardness sheet33, or the OCA film is attached to a rear side of the finished high-hardness sheet33. Such attachment of the high-hardness sheet33to the body31is performed by a roll lamination process, that is, transferring the high-hardness sheet33and the OCA film while pressurizing the high-hardness sheet33and the OCA film which faces the rear side of the high-hardness sheet33with a roller. A thickness of the OCA film is preferably less than 100 micrometer, and to improve adhesive strength, the rear side of the high-hardness sheet33may be nitrogen-plasma-processed before the OCA film is attached thereto.

After the OCA film is attached to the high-hardness sheet33, the high-hardness sheet33is disposed such that the OCA film faces the outer surface of the fabricated body31, and then the roll lamination process is performed. Referring toFIGS. 4A through 5, when the body31is disposed on a separate jig41used in the roll lamination process, a pressurization is applied by a roller43and the jig41is transferred such that the high-hardness sheet33is attached to the body31.

If there are bubbles between the high-hardness sheet33and the OCA film or between the OCA film and the surface of the body31after the attachment of the high-hardness sheet33to the body31, the bubbles are preferably removed using an autoclave. To this end, the body31to which the high-hardness sheet33is attached is placed in the inner side of the autoclave and is left for a period of 40 minutes or more and 1 hour or less, at the pressure of 10 kgf/cm2or more and 15 kgf/cm2or less, thereby removing the bubbles.

The process of attaching the high-hardness sheet33to the body31using an UV curing adhesive is shown inFIG. 6. As shown, the process of attaching the high-hardness sheet33to the body31using an UV curing adhesive is performed on a conveyer belt on which an adhesive distributer47, the roller43, and an UV curing chamber45are sequentially disposed in that order.

When the body31of the window member30is disposed on the jig41, the jig41is transferred and an UV curing adhesive49is applied onto the outer surface of the body31in a predetermined pattern via an adhesive distributer47. When the body31onto which the UV curing adhesive49is applied is transferred to the roller43, the high-hardness sheet33is disposed on the outer surface of the body31, and the body31is continuously transferred and passes through the roller43. The roller43pressurizes the high-hardness sheet33to urge the high-hardness sheet33to closely contact the body31. UV curing adhesive leaking through edges of the body31and the high-hardness sheet33is preferably removed using a solvent such as ethanol. Thereafter, the body31having passed through the roller43goes to the UV curing chamber45in which the UV curing adhesive49between the high-hardness sheet33and the body31is cured, such that the high-hardness sheet33is completely attached to the body31.

FIGS. 3A through 3Dshow the window member30that may be fabricated through the foregoing process.FIG. 3Ais a plane view of the window member30, in which a bezel37printed onto the high-hardness sheet33is disposed around a transparent window35. On the inner side of the window member30, more particularly, on the inner side of the body31may be formed structures for binding to a housing, etc., of a portable terminal and the structures for binding to the housing are hidden by the bezel37.FIGS. 3B,3C, and3D are side views of the window member30, and different curved shapes of the outer side of the window member30that may be formed using the foregoing process.

As can be appreciated from the foregoing description, the method for fabricating a window member for a display device of a portable terminal according to the present invention attaches the high-hardness sheet to the body of the window member, thus easily securing surface hardness. Moreover, the window member is fabricated through an injection molding, and the high-hardness sheet is attached to the window member through a roll lamination or a double injection, such that surface quality such as surface uniformity can be easily achieved. Furthermore, a separate surface process suing a tempered glass is not necessary as in the prior art, which in turn allows a mass production of the window member at a low cost. In addition, since the body of the window member is fabricated through an injection molding, the window member having various shapes of a curved surface may be formed. Moreover, by printing a logo of a manufacturer or a common carrier onto the high-hardness sheet, various structures formed in the edge of the body of the window member can be hidden, thus making it easy to form structures for assembly of the window member.

While detailed embodiments have been described in the present invention, it would be obvious to those of ordinary skill in the art that various changes may be made without departing from the scope of the present invention.