KR20230136352A - Method for manufacturing back cover of display device with improved characteristics of curved portion - Google Patents

Abstract

The present invention relates to a method of manufacturing a back cover of a display device, and more specifically, to a method of manufacturing a back cover of a display device that improves problems with curved parts that occur during the molding process.

Description

Method for manufacturing back cover of display device with improved characteristics of curved portion}

The present invention relates to a method of manufacturing a back cover of a display device, and more specifically, to a method of manufacturing a back cover of a display device that improves problems with curved parts that occur during the molding process.

Recently, with the development of mobile phone and smartphone technology, mobile phones and smartphones (hereinafter collectively referred to as 'mobile phones') of various designs are being released. These mobile phones are composed of a case that makes up the exterior, and various circuit parts mounted inside the case to perform the original functions of the mobile phone.

Among them, a back cover for a mobile phone refers to a case that is attached to the back of a mobile phone device. These back covers not only protect mobile phones from external shocks, but recently, various materials have been developed to improve aesthetics to suit the tastes of modern people, as well as color, gloss, and patterns (i.e., patterns). Attempts are being made to include design elements such as

In general, plastic injection molded products are widely used as materials for making back covers, and recently, back covers made of metal or glass, which can achieve a thin thickness of about 0.5 mm and a sophisticated appearance, are also in the spotlight. there is.

Meanwhile, during the forming process, which is essential when manufacturing a back cover, a folded part (bending) occurs, and this part appears curved like a band due to the refractive index of light. Therefore, there is a need for research on process technology in this field that can improve various problems that arise due to the occurrence of such bends.

Republic of Korea Patent Publication No. 10-2005-0073212

The present invention is intended to solve the above problems, and seeks to provide a method of manufacturing a back cover of a display device that minimizes the outer curved surface value (R value) of the bending portion that occurs during the molding process step to have a straight shape. .

The above and other objects and advantages of the present invention will become apparent from the following description of preferred embodiments.

The above object includes preparing a substrate; Supplying the substrate to a molding machine; Molding the substrate by placing it on a mold of the molding machine and pressing it; Obtaining a bent portion of the substrate formed by folding it according to the shape of the mold after the molding step; A primary processing step of processing the outer surface of the substrate; and a secondary processing step of processing the entire outline of the substrate after primary processing. It can be achieved by a method of manufacturing a back cover of a display device, including.

The substrate includes polycarbonate (PC), polymethyl methacrylate (PMMA), polycarbonate polymethyl methacrylate (PCPMMA), polyvinyl chloride (PVC), ABS resin, polypropylene (PP), It is characterized by being made of a plastic sheet such as polystyrene (PS) or polyethylene terephthalate (PET), glass, or a metal material containing aluminum (Al).

The molding machine is characterized by including a molding machine that sprays high-pressure air to pressurize the molding machine. The molding is characterized in that the molding is performed by spraying 55 to 80 kg/cm ² of air and pressurizing for 5 to 10 minutes under conditions in which heat is applied in a temperature range of 130 to 140°C.

The curved portion may be formed by forming a fan-shaped round surface with a certain curvature on at least one of each end portion (edge portion) extending from a flat straight surface in the substrate.

The primary processing is to reduce the area of the outer curved surface (R) of the curved portion by cutting the surface of the straight surface of the substrate, and the cutting extends from the straight surface to the boundary where the curved portion begins. It is characterized by being carried out.

The primary processing is characterized in that precise cutting is performed using a method selected from the group consisting of machine tools (CNC (computer numerical control)), lasers, and polishing.

According to the present invention, it is possible to improve problems with curved parts that occur during the molding process performed when manufacturing the back cover of a display device.

Specifically, in order to overcome the technical limitation of reducing the curvature of the bent part below a certain size, which is a problem that occurs during all conventional forming and injection processes, the outer curved surface value (R value) of the bent part is processed to a minimum. As a result, it is possible to achieve a sharp, straight shape that is almost at a right angle. As a result, it is possible to secure improved aesthetics by providing sharpness and luxury in design compared to existing technology.

However, the effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description below.

Figure 1 is a photograph showing a bent portion that appears during a conventional molding process.
Figure 2 is a schematic diagram schematically showing the molding step in the manufacturing method according to an embodiment of the present invention.
Figure 3 is a schematic diagram schematically showing the first processing step in the manufacturing method according to an embodiment of the present invention.
Figure 4 is a photograph showing a molded product manufactured according to the prior art, and Figures 5 and 6 are photographs showing a molded product manufactured according to an embodiment of the present invention.
Figures 7 and 8 are pictures taken with a scanning electron microscope (SEM) of the bent part before and after performing the first processing step of an embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to embodiments of the present invention and drawings. These examples are merely presented as examples to explain the present invention in more detail, and it will be apparent to those skilled in the art that the scope of the present invention is not limited by these examples. .

Additionally, unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by a person skilled in the art to which the present invention pertains, and in case of conflict, this specification including definitions The description will take precedence.

In order to clearly explain the proposed invention in the drawings, parts unrelated to the description have been omitted, and similar reference numerals have been assigned to similar parts throughout the specification. And, when it is said that a part "includes" a certain component, this does not mean excluding other components, but may further include other components, unless specifically stated to the contrary. Additionally, “unit” as used in the specification refers to a unit or block that performs a specific function.

Identification codes (first, second, etc.) for each step are used for convenience of explanation. The identification codes do not describe the order of each step, and each step does not clearly state a specific order in context. It may be carried out differently from the order specified above. That is, each step may be performed in the same order as specified, may be performed substantially simultaneously, or may be performed in the opposite order.

The term "bent portion" in the present invention and this specification refers to a portion where a bend is formed that occurs during a forming process, specifically, during molding using a mold, as shown in Figure 1. It is similar to other terms commonly used in the field, such as round surface/part, bending surface/part, etc.

However, in one embodiment of the present invention, the meaning of “bent portion” is not limited to referring to only a specific part, and may be interpreted broadly and comprehensively depending on the technical field to which it is applied.

In addition, as an example of a display device to which the "molding process step" of the present invention can be applied, a back cover for a mobile phone is described, but it is not limited thereto, and the display device can be molded for example, home appliances, vehicles, etc. Any device that is manufactured including the (forming) process is possible.

One aspect of the present application includes preparing a substrate; Supplying the substrate to a molding machine; A step of positioning the substrate on a mold of the molding machine and forming it by pressing; Obtaining a curved portion of the substrate formed by folding it according to the shape of the mold after the molding step; A primary processing step of processing the outer surface of the substrate; and a secondary processing step of processing the entire outline of the substrate after primary processing. Provides a method of manufacturing a back cover of a display device, including.

Hereinafter, implementation examples and examples of the present application will be described in detail with reference to the attached drawings. However, the present disclosure may not be limited to these implementations, examples, and drawings.

First, the substrate can be prepared. The base material is a base material on which a later molding process will be performed and may be a thin, flat material applied to a display device, for example, the back cover of a mobile phone.

The substrate includes polycarbonate (PC), polymethyl methacrylate (PMMA), polycarbonate polymethyl methacrylate (PCPMMA), polyvinyl chloride (PVC), ABS resin, polypropylene (PP), It may be a plastic sheet such as polystyrene (PS) or polyethylene terephthalate (PET), or it may be made of glass or a metal material containing aluminum (Al). However, the materials described above are not limited thereto, and any material that can perform a forming process in the relevant field is possible.

For example, the substrate may be polycarbonate (PC), polymethyl methacrylate (PMMA), polycarbonate polymethyl methacrylate (PCPMMA), or a combination thereof.

The substrate may include a sheet made of the above-described material or a printed layer formed on one side of the layered structure. For example, the substrate may include a color printing layer formed on one side of the PC substrate or on one side of the PCPMMA substrate through a gravure printing process or the like. However, with respect to the structures stacked on or including the other side of the substrate, essential or optional configurations used in the art may be included without significant limitation.

The thickness of the substrate may be, for example, 1.0 mm or less, specifically, 0.01 mm to 1.0 mm, more specifically, 0.01 to 1 mm, but is not limited thereto.

Next, the substrate is supplied to the molding machine. The molding machine is not particularly limited as long as it can perform general molding methods used in the field, such as injection thermoforming, vacuum molding, and pressure molding.

As an example, the molding machine may be a pressure molding machine, specifically, a molding machine that sprays high-pressure air to pressurize the molding machine. By applying pressure by spraying air, deformation or damage to the substrate can be prevented and more precise forming can be achieved. The pressing may be performed under certain conditions of heat and pressure, and these conditions may be appropriately adjusted depending on the type of substrate and desired shape.

As an example, when polycarbonate (PC), polymethyl methacrylate (PMMA), polycarbonate polymethyl methacrylate (PCPMMA), or a combination thereof is used as the substrate, a temperature of 130 to 140 ° C. Molding can be performed by spraying air at 55 to 80 kg/cm ² and pressurizing for 5 to 10 minutes under conditions in which heat is applied.

Figure 2 is a schematic diagram schematically showing the molding process steps according to an embodiment of the present invention.

Referring to FIG. 2, the mold 200 has a flat straight surface and each end portion (edge portion) extending from the straight surface, and at least one of the end portions has a fan-shaped round surface with a certain curvature ( 210).

Forming is performed by placing the substrate 100 on the mold 200 and applying pressure from the outside to change the shape of the substrate 100. Accordingly, the substrate 100 has a layered structure with a certain thickness, has a flat straight surface in the center, and has each end (edge part) extending from the straight surface, and at least one of each end has a flat straight surface. A curved portion 110 may be formed to form a fan-shaped round surface with a certain curvature.

Specifically, the curved portion 110 has an outer curved surface (R) and an inner curved surface (R'), and these outer curved surfaces (R) and inner curved surfaces (R') inevitably have a gently curved shape, especially , a phenomenon occurs in which the degree of bending (bending) of the outer curved surface (R) becomes excessively gentle.

If the curved portion 110, especially the outer curved surface R, is too gentle, an engraving may occur on the curved surface and the curved surface may become uneven and stand out, which may reduce visibility, and it is difficult to change it to various shapes in terms of design. You lose. Therefore, in one embodiment of the present invention, the shape of the bent portion 110 is intended to be formed in a sharper straight line shape that is almost a right angle.

To this end, if a mold whose shape itself is a right angle is used, there is a problem that the substrate 100 is torn or cracks occur during the molding process, and making the mold shape into a precise right angle is also a problem in the current process in the field. This is not easy and there is a problem that costs increase. In other words, there are many practical difficulties in molding the bent portion of the substrate into a sharp and precise right-angled shape without damaging the substrate through the shape of the mold.

Accordingly, in one embodiment of the present invention, the above-described problem is attempted to be overcome through the primary processing step described below.

Figure 3 is a schematic diagram schematically showing the first processing step in the manufacturing method according to an embodiment of the present invention.

Referring to FIG. 3, a first processing step of processing the outer surface of the substrate 100 may be performed. The primary processing refers to a surface processing process of cutting the surface of the straight surface 120 of the substrate 100, and specifically, the boundary surface extending from the straight surface 120 and where the curved portion 110 begins. By cutting up to (circled), the area of the outer curved surface (R) can be significantly reduced compared to before the first processing.

As a result, the boundary surface (boundary line) where the bent portion 110 begins is finished more precisely with a sharper cross-section (single line), while significantly reducing concerns about damage such as cracks or tears to the substrate 100. You can.

For example, it is preferable that the thickness of the straight surface 120 on which the primary processing, that is, the cutting, is performed is 0.7 to 0.8% of the thickness of the width of the substrate 100.

The primary processing may use methods capable of precise cutting, such as machine tools (computer numerical control (CNC)), lasers, polishing, etc.

Specifically, the primary processing may use, for example, a machine tool (computer numerical control (CNC)) using a cutting method such as milling, lathe, or drilling. The primary processing method may vary depending on the type of material of the substrate 100.

As an example, when using polycarbonate (PC), polymethyl methacrylate (PMMA), polycarbonate polymethyl methacrylate (PCPMMA), or a combination thereof as the substrate, for example, an end mill bite. It is desirable to use

After the primary processing, the marks remaining after the primary processing can be completely removed using a CNC Brush Bite. As a result, a sharper and neater finish can be achieved for the substrate.

Next, a secondary processing step may be performed in which the overall outline of the substrate is refined and processed. The secondary processing involves performing, for example, additional cutting, cutting, perforation, grinding, etc. to suit the desired overall appearance of the base material. As a specific secondary processing method, methods commonly used in the field can be used without limitation.

Other than the above-described process steps, processes that are usually required or optionally performed in the relevant field, that is, the mobile phone back cover manufacturing field, can be performed without significant restrictions.

Figure 4 is a photograph showing a molded product manufactured according to the prior art, and Figures 5 and 6 are photographs showing a molded product manufactured according to an embodiment of the present invention.

Referring to FIGS. 4 to 6 together, it can be seen that in the case of FIG. 4, the curved portion is too gentle, so an engraving is formed on the curved surface, and the finish is not neat. On the other hand, in the case of FIGS. 5 and 6, it can be confirmed that the boundary surface between the straight surface and the curved portion is formed in a sharp straight line by performing primary processing (straight surface cutting) of the substrate. Among them, in Figure 6, it can be seen that a sharper and neater finish was achieved by completely removing the marks using a CNC Brush Bite after the primary processing (straight surface cutting) of the substrate. .

Figures 7 and 8 are pictures taken with a scanning electron microscope (SEM) of the bent part before and after performing the first processing step of an embodiment of the present invention.

Referring to Figures 7 and 8 together, it can be seen that by cutting the straight side of the substrate to a predetermined thickness, the outer curved surface (R) value area of the curved portion in Figure 8 is significantly reduced compared to Figure 7, thereby realizing a sharper shape. there is.

According to one embodiment of the present invention, it is possible to improve the problem of bending parts that occur during the molding process performed when manufacturing a display device, for example, a back cover of a mobile phone.

Specifically, in order to overcome the technical limitation of reducing the curvature of the bent part below a certain size, which is a problem that occurs during all conventional forming and injection processes, the outer surface value (R value) of the bent part is processed to a minimum. As a result, it is possible to achieve a sharp, straight shape that is almost at a right angle.

As a result, in terms of design, it is possible to secure further improved aesthetics by providing sharpness and a luxurious-feeling finish compared to existing technologies, and it is possible to easily change into more diverse shapes without fear of damage to the substrate. It can have the effect of:

As described above, embodiments according to the present invention have been described with reference to the attached drawings, but the present invention is not limited to the above-described embodiments and may be modified in various forms within the scope of the technical idea to which the present invention pertains. This can be said to be self-evident.

100: base material 110: bent portion of base material
120: Straight surface of the substrate
200: Mold 210: Round surface/part of mold

Claims (7)

Preparing a substrate;
Supplying the substrate to a molding machine;
Molding the substrate by placing it on a mold of the molding machine and pressing it;
Obtaining a bent portion of the substrate formed by folding it according to the shape of the mold after the molding step;
A primary processing step of processing the outer surface of the substrate; and
A secondary processing step of processing the entire outline of the substrate after primary processing; A method of manufacturing a back cover of a display device, including. According to paragraph 1,
The substrate includes polycarbonate (PC), polymethyl methacrylate (PMMA), polycarbonate polymethyl methacrylate (PCPMMA), polyvinyl chloride (PVC), ABS resin, polypropylene (PP), A method of manufacturing a back cover for a display device, characterized in that it is made of a plastic sheet such as polystyrene (PS) or polyethylene terephthalate (PET), glass, or a metal material containing aluminum (Al). According to paragraph 1,
A method of manufacturing a back cover of a display device, characterized in that the molding machine includes a molding machine that sprays and pressurizes high-pressure air. According to paragraph 3,
The molding is performed by spraying 55 to 80 kg/cm ² of air and pressurizing the display device for 5 to 10 minutes under conditions where heat is applied in a temperature range of 130 to 140°C. Back cover manufacturing method. According to paragraph 1,
The bend part,
In the above substrate, a fan-shaped round surface with a certain curvature is formed on at least one of each end portion (edge portion) extending from a flat straight surface. According to clause 5,
The primary processing is to reduce the area of the outer curved surface (R) of the curved portion by cutting the surface of the straight side of the substrate,
A method of manufacturing a back cover of a display device, characterized in that the cutting extends from the straight surface to a boundary surface where the curved part begins. According to clause 6,
The primary processing is a method of manufacturing a back cover of a display device, characterized in that precise cutting is performed using a method selected from the group consisting of machine tools (CNC (computer numerical control)), laser, and polishing. .