Ultra-precision light guide plate injection mold for virtual reality

Abstract

The present invention relates to an ultra-precision light guide plate injection mold for VR, and more specifically, to an ultra-precision light guide plate injection mold for VR that can improve defects such as air traps or weld lines occurring in the corner areas of a light guide plate molded product by installing a pair of overflows, respectively, in an area where a gate is installed on one side of the mold body and on the other side of the mold body. The present invention is characterized by comprising: a mold body portion having a cavity filled with molten resin; a gate portion disposed on one side of the mold body portion and supplying molten resin to the cavity; a first overflow portion provided between the mold body portion and the gate portion; and a second overflow portion provided on the other side of the mold body portion.

Description

Technology Field

[0001] The present invention relates to an ultra-precision light guide plate injection mold for VR, and more specifically, to an ultra-precision light guide plate injection mold for VR that can improve defects such as air traps or weld lines occurring in the corner areas of a light guide plate molded product by installing a pair of overflows, respectively, in an area where a gate is installed on one side of the mold body and on the other side of the mold body. Background Technology

[0003] Generally, Liquid Crystal Displays (LCDs) used in TVs, mobile phones, navigation systems, etc., are light-receiving elements that do not emit light on their own; therefore, a Back Light Unit (BLU) in the form of a back light source is required to maintain uniform brightness across the entire screen. Such a Back Light Unit used in an LCD is equipped with a Light Guide Panel (LGP) to induce the refraction or scattering of light to convert an initial point light source or linear light source (e.g., LED) into a planar light source.

[0004] Recently, as liquid crystal displays have become lighter and thinner, there is a growing need to manufacture even thinner and lighter light guide plates.

[0005] However, the following problems exist in the conventional manufacturing of light guide plates.

[0006] Conventionally, it was manufactured by creating a mold identical to the shape of the light guide plate and injecting it, but incomplete parts occur when the final light guide plate is thinner than 1mm.

[0007] That is, as illustrated in FIG. 9a, the air inside the mold (200) is compressed and not discharged on the opposite side of the gate (210) into which the molding resin (100) is injected. Although an air vent is formed in the mold itself to allow air to escape, the air vent alone has a limit to the amount of air discharged, so the molding resin (100) is not filled to the end of the mold (200) by the compressed air. As such, since the molding resin (100) is not filled to the end of the mold (200), an unmolded portion (A) occurs.

[0008] In addition, the filling of the molding resin (100) is often slowed down by the compressed air inside the mold (200), resulting in reduced productivity.

[0009] As a prior art patent for solving these problems, Korean Published Patent No. 10-2009-0077265 discloses a mold for manufacturing a light guide plate, comprising a main body portion in which a molding resin is filled inside in the shape of a light guide plate to be finally molded as shown in FIG. 9b, a gate provided on one side of the main body portion for injecting the molding resin so as to fill the inside of the main body portion, and an overflow provided on the other side of the main body portion and connected to the main body portion for filling the inside with the molding resin.

[0010] However, in the case of the aforementioned disclosed patent, while defects in formability at the end opposite the gate can be improved, there was a problem in that it could not solve issues such as molding defects at the part in contact with the gate, such as the occurrence of air traps or weld lines. Prior art literature

[0012] Republic of Korea Published Patent No. 10-2009-0077265 The problem to be solved

[0013] The present invention has been devised to solve the problems of the prior art, and the objective of the present invention is to provide a light guide plate injection mold capable of improving defects such as air traps or weld lines occurring in the corner areas of a light guide plate molded product by installing a pair of overflows on the area where a gate is installed on one side of the mold body and on the other side of the mold body, respectively.

[0014] In addition, the objective of the present invention is to provide a light guide plate injection mold that can utilize 95 to 100% of the effective diameter area when the effective diameter is small, such as for ultra-precision light guide plates for VR, and can significantly improve mass production capabilities.

[0015] The problems to be solved by the present invention are not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0017] To achieve the above-mentioned objective, the light guide plate injection mold according to the present invention is characterized by comprising: a mold body portion having a cavity filled with molten resin; a gate portion disposed on one side of the mold body portion and supplying molten resin to the cavity; a first overflow portion provided between the mold body portion and the gate portion; and a second overflow portion provided on the other side of the mold body portion.

[0018] In addition, in the light guide plate injection mold according to the present invention, the molten resin supplied through the gate portion is characterized by being filled by sequentially passing through the first overflow portion, the cavity, and the second overflow portion, and then flowing back from the cavity to fill the second overflow portion.

[0019] In addition, in the light guide plate injection mold according to the present invention, the first overflow portion is composed of a first connecting portion, one end of which is in communication with the gate portion and the other end of which is in communication with the cavity, and a first pocket portion that is in communication with the first connecting portion; the second overflow portion is composed of a second connecting portion, one end of which is in communication with the cavity, and a second pocket portion that is in communication with the other end of the second connecting portion; and the first overflow portion and the second overflow portion are arranged on one side and the other side of the mold body portion facing each other.

[0020] In addition, in the light guide plate injection mold according to the present invention, the first connecting part and the second connecting part each have a left-right width corresponding to the cavity, and the first pocket part and the second pocket part each have an extension part having a left-right width larger than the cavity, and the first connecting part and the second connecting part have an upper-lower width smaller than the cavity and are characterized by communicating with the upper end of the cavity.

[0021] In addition, in the light guide plate injection mold according to the present invention, the mold body portion is composed of a plurality of parts, and the molten resin supplied through a single sprue is supplied to the plurality of mold body portions through a runner connected to each mold body portion and a gate portion. Effects of the invention

[0023] According to the light guide plate injection mold of the present invention, by installing a pair of overflows on the area where a gate is installed on one side of the mold body and on the other side of the mold body, respectively, it is possible to improve defects such as air traps or weld lines occurring in the corner areas of the light guide plate molded product.

[0024] In addition, according to the light guide plate injection mold of the present invention, when the effective diameter is small, such as in ultra-precision light guide plates for VR, 95 to 100% of the effective diameter can be used, and there is an effect of greatly improving mass production.

[0025] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description below. Brief explanation of the drawing

[0027] FIG. 1 is a perspective view illustrating a light guide plate injection mold according to the present invention. FIG. 2 is a bottom exploded perspective view illustrating a light guide plate injection mold according to the present invention. FIG. 3 is a cross-sectional view illustrating a light guide plate injection mold according to the present invention. FIG. 4 is a schematic diagram showing the filling flow of molten resin within the mold of the present invention. FIG. 5 is a schematic diagram showing the reverse flow in which molten resin fills the first overflow section and then moves to the cavity and the second overflow section within the mold of the present invention. FIG. 6 is a drawing comparing whether defects occur in a conventional mold in which only the second overflow portion is formed, and in the mold of the present invention which is equipped with first and second overflow portions. FIG. 7 is a perspective view showing a light guide plate formed through the mold of the present invention. FIGS. 8A and 8B are drawings showing a structure in which a plurality of mold body parts are combined in a light guide plate injection mold according to the present invention. Figures 9a and 9b are drawings illustrating a conventional mold for manufacturing a light guide plate. Specific details for implementing the invention

[0028] Preferred embodiments of the present invention will be described in detail below.

[0029] In describing the present invention, specific descriptions of related known functions or configurations are omitted if it is determined that such descriptions would unnecessarily obscure the essence of the invention. Furthermore, the terms described below are defined considering their functions in the present invention, and these definitions may vary depending on the intentions of the user or operator, or judicial precedents. Therefore, their definitions should be based on the content throughout this specification.

[0031] FIG. 1 is a perspective view illustrating a light guide plate injection mold according to the present invention, FIG. 2 is a bottom exploded perspective view illustrating a light guide plate injection mold according to the present invention, and FIG. 3 is a cross-sectional view illustrating a light guide plate injection mold according to the present invention. FIG. 4 is a diagram schematically showing the filling flow of molten resin within the mold of the present invention, and FIG. 5 is a diagram schematically showing the reverse flow in which molten resin moves to the cavity and the second overflow section after filling the first overflow section within the mold of the present invention.

[0032] Referring to FIGS. 1 to 7, a light guide plate injection mold (100) according to the present invention may be configured to include a mold body part (110) having a cavity (111) filled with molten resin inside, a gate part (103) disposed on one side of the mold body part (110) and supplying molten resin to the cavity (111), a first overflow part (130) provided between the mold body part (110) and the gate part (103), and a second overflow part (150) provided on the other side of the mold body part (110).

[0033] The above mold body part (110) may be structured such that the upper mold body part (110a) and the lower mold body part (110b) can be separated vertically.

[0034] The gate portion (103) above serves to supply molten resin supplied through the sprue (101) and the runner (102) to the mold body portion (110) through the first overflow portion (130), and may be exemplified as a fan gate structure, but is not limited thereto.

[0035] The first overflow portion (130) may be composed of a first connecting portion (131) which is connected to the gate portion (103) at one end and connected to the cavity (111) at the other end, and a first pocket portion (133) which is connected to the first connecting portion (131).

[0036] The second overflow portion (150) may be composed of a second connecting portion (151) having one end communicating with the cavity (111) and a second pocket portion (153) communicating with the other end of the second connecting portion (151).

[0037] The first overflow section (130) and the second overflow section (150) are positioned on one side and the other side of the mold body facing each other.

[0038] The first connecting part (131) and the second connecting part (151) each have a left-right width corresponding to the cavity (111), have a lower-up width smaller than the cavity (111), and are structured to be in communication with the upper end of the cavity (111).

[0039] The first pocket portion (133) and the second pocket portion (153) may each have a first extension portion (133a) and a second extension portion (153a) such that they have a left-right width greater than that of the cavity (111) to the first and second connecting portions (131, 151).

[0040] Meanwhile, as shown in FIG. 4, the molten resin supplied through the gate section (103) is filled by passing through the first overflow section (130), the cavity (111), and the second overflow section (150) in sequence, and then flows back from the cavity (111) to fill the second overflow section (150).

[0041] When molten resin is supplied to the cavity (111) and the second overflow section (150) through the first overflow section (130), the air inside the cavity (111) is collected in the second overflow section (150), and in particular, is collected in the second expansion section (153a) provided on the left and right sides. Therefore, even if the molten resin flows backward as shown in FIG. 5, the air or bubbles trapped in the second expansion section (153a) do not flow backward toward the cavity.

[0042] And after the molten resin is filled in the second overflow section (150), as shown in FIG. 5, some of the molten resin inside the cavity (111) flows back toward the first overflow section (130), and the air or bubbles remaining inside the cavity (111) escape through the first connecting section (131) to the first overflow section (130), particularly the first expansion section (133a), and collect therein.

[0043] In this regard, FIG. 6 is a drawing comparing the occurrence of defects in a conventional mold in which only the second overflow section is formed and in the mold of the present invention equipped with first and second overflow sections. As shown in FIG. 6 (a), when the overflow section is installed only on one side of the mold body, an air trap and a weld line are formed on the corner side in contact with the gate section. However, as shown in FIG. 6 (b), when the first overflow section is additionally installed between the mold body and the gate section, an air trap and a weld line are formed in the extended portion of the first overflow section, so no product defects occur. For reference, in FIG. 6, the area where the air trap and weld line are formed is indicated by a red dot.

[0044] Here, if the first and second expansion sections are not provided in the first and second overflow sections, for example, when the molten resin in the second overflow section flows back toward the cavity, air or bubbles may also flow back along with it, causing defects; therefore, it is desirable to provide an expansion section in the overflow section.

[0045] Meanwhile, FIGS. 8a and 8b are drawings showing a structure in which a plurality of mold body parts are combined in a light guide plate injection mold according to the present invention.

[0046] In the light guide plate injection mold of the present embodiment, a pair of mold body parts (110, 100a) may be arranged left and right based on the sprue (101) as shown in FIG. 8a, and four mold body parts (110, 100a, 110b, 110c) may be arranged up, down, left, and right as shown in FIG. 8b, but are not limited thereto and two or more may be arranged.

[0047] In this case, the molten resin supplied through a single sprue (101) is supplied to a plurality of mold bodies through each runner (102) connected to each mold body part (110, 100a, 110b, 110c) and each gate part (103).

[0049] The invention described above is merely illustrative, and those skilled in the art will readily understand that various modifications and equivalent alternative embodiments are possible therefrom. Therefore, it will be understood that the invention is not limited only to the forms mentioned in the detailed description above. Accordingly, the true technical scope of protection of the invention should be determined by the technical spirit of the appended claims. Furthermore, the invention should be understood to include all modifications, equivalents, and substitutions within the spirit and scope of the invention as defined by the appended claims. Explanation of the symbols

[0051] 100 : Light guide plate injection mold 101 : Sprue 102 : Runner 103 : Gate Section 105, 106: Ejector Pin 110: Mold Body 110a: Upper mold body part 110b: Lower mold body part 111 : Cavity 130 : First overflow section 131: First connecting part 133: First pocket part 133a : 1st expansion section 150 : 2nd overflow section 151 : Second connecting part 153 : Second pocket part 153a : Second extension part 10 : Light guide plate molded product

Claims

Claim 1 A light guide plate injection mold comprising: a mold body portion having a cavity filled with molten resin; a gate portion disposed on one side of the mold body portion and supplying molten resin to the cavity; a first overflow portion provided between the mold body portion and the gate portion; and a second overflow portion provided on the other side of the mold body portion; wherein the molten resin supplied through the gate portion is filled by sequentially passing through the first overflow portion, the cavity, and the second overflow portion, and then flows back from the cavity to fill the second overflow portion. Claim 2 delete Claim 3 A light guide plate injection mold according to claim 1, wherein the first overflow portion is composed of a first connecting portion, one end of which is in communication with the gate portion and the other end of which is in communication with the cavity, and a first pocket portion that is in communication with the first connecting portion, and the second overflow portion is composed of a second connecting portion, one end of which is in communication with the cavity, and a second pocket portion that is in communication with the other end of the second connecting portion, and wherein the first overflow portion and the second overflow portion are disposed on one side and the other side of the mold body portion facing each other. Claim 4 A light guide plate injection mold according to claim 3, wherein the first connecting part and the second connecting part each have a left-right width corresponding to the cavity, and the first pocket part and the second pocket part each have an extension part having a left-right width larger than the cavity, and the first connecting part and the second connecting part have an upper-lower width smaller than the cavity and are in communication with the upper end of the cavity. Claim 5 A light guide plate injection mold according to claim 1, wherein the mold body portion is composed of a plurality of parts, and the molten resin supplied through a single sprue is supplied to a plurality of mold body portions through a runner connected to each mold body portion and a gate portion.

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