JP4013475B2 - Method for manufacturing light guide plate of surface light emitting device - Google Patents

Description

【００１６】
したがって、本実施の形態において、導光板１の光入力部１ｂと面発光部１ａとの境界における第２の主面の段差Ｔは、金型の光入力部ブロック３３の試料上面３３ａとスライドブロック３２の上面３２ａとの間の金型段差ｔと成形条件特に成形圧力（射出圧力）とを考慮して設定される。
【００１７】
また、本発明において、導光板１の材料として適した材料は、アクリル及びポリカーボネートである。以下、表２にその物性と成形収縮率について示す。
表２

【００１８】
【実施例】
以下、本発明に係る実施例について説明する。
本発明に係る実施例として、第２の主面１３において光入射部１ｂが面発光部１ａより低くなるように形成した本発明に係る導光板であって、段差Ｔの値が異なる１２個の導光板をアクリルを用いて作製し、その導光板を用いて面発光装置を構成したときの輝度を測定した。その結果を図６のグラフに示す。
尚、図６には第２の主面１３において光入射部１ｂが面発光部１ａより高くなるように形成した本発明の範囲外の導光板を比較例として作製し、その本発明の範囲外の導光板を用いて面発光装置を構成したときの輝度を比較のために示した。図６において、段差Ｔの値が負（マイナス）である×印で示した点が比較例に係るものである。
【００１９】
以上の図６に示す結果から明らかなように、本発明に係る実施例の導光板は、比較例の導光板より輝線の輝度を低くできる。
また、図６のグラフからわかるように、本発明において、輝線の輝度を効果的に低くするために、その段差Ｔは８０μｍ以下であることが好ましく、１０μｍ以上、６０μｍ以下に設定することがさらに好ましい。
【００２０】
【発明の効果】
以上説明したように、本発明に係る面発光装置の導光板は、発光ダイオードから入力された光を拡散させる光入力部と光入力部によって拡散された光を上記第１の主面から出射する面発光部とからなり、上記光入力部が上記第２の主面において上記光入力部と上記面発光部との境界に上記光入力部側が低くなるような段差が生じるように上記面発光部に比較して薄く形成されているので、発光ダイオードから入力された光は段差部で等方向に分散されて面発光部１ａに入力され、光入力部と面発光部の境界の近傍における輝線の発生を抑制できる。
これにより、本発明によれば、割型構造の金型を用いて製造した場合においても、面発光装置に生じる輝線を実質的に無くすことができる面発光装置の導光板を提供することができる。
【図面の簡単な説明】
【図１】 本発明に係る実施の形態の導光板の構成を示す斜視図である。
【図２】 （ａ）は、図１の導光板の断面図であり、（ｂ）は比較のために示した本発明の範囲外の導光板の断面図である。
【図３】 本実施の形態の導光板を製造するための中型の斜視図である。
【図４】 （ａ）は実施の形態の導光板の断面図であり、（ｂ）は図３の中型の断面図である。
【図５】 実施の形態の上型と下型の斜視図である。
【図６】 本発明に係る実施例の段差Ｔに対する輝線の輝度を示すグラフである。
【図７】 一般的な面発光装置の構成を示す平面図である。
【符号の説明】
１ 導光板、１ｂ 光入力部、１ａ 面発光部、１０ 段差部、１２ 第１の主面、１３ 第２の主面、３０ 中型、３１ 固定ブロック、３１ａ 凹部、３２スライドブロック、３３ 光入力部ブロック、３３ｂ ランナー、３４ 突き出しピン、３５ キャビティー、４１ 上型、４２ 下型。[0001]
BACKGROUND OF THE INVENTION
The present invention is mainly a liquid crystal backlight, panel meters, used like lights, surface-emitting switches relates to a manufacturing method of the light guide plate of the surface light-emitting device using a light emitting diode.
[0002]
[Prior art]
2. Description of the Related Art In recent years, surface light emitting devices that emit light from LED chips, which are point light sources, in a planar shape are used as light sources such as liquid crystal backlights. This surface light emitting device is configured to allow light from one or more light emitting diodes to enter from one end surface of a light guide plate having opposing main surfaces and to emit light from the entire one main surface of the light guide plate. The
That is, as shown in the plan view of FIG. 7, the outer frame 903 has a first main surface and a second main surface and is made of a transparent resin, and faces the end surface of the light guide plate 901. A light-emitting diode 902 provided on the second main surface side of the light guide plate, and a reflector (not shown) provided on the second main surface side of the light guide plate. Light is emitted from the entire main surface of the film.
In the surface light emitting device configured as described above, the light guide plate 901 is manufactured by injection molding, in which a light diffusing portion 911 including, for example, a plurality of grooves is formed on an end surface on which the light emitting diode 902 is opposed. In this light guide plate 901, the light input portion 901b on the light emitting diode side from the broken line 920 needs to be formed in various shapes corresponding to the shape or the number of the light emitting diodes opposed to each other, whereas the surface light emitting portion 901a. Since standardization is possible among a plurality of models, the types of shapes can be reduced compared to the light input unit 901b.
Under these circumstances, the mold for injection molding for manufacturing the light guide plate is a split mold (split mold structure) in which the mold for forming the light input portion 901b and the mold for forming the surface light emitting portion 901a are combined. If the mold for forming the surface light emitting portion 901a can be made common even between different models, the manufacturing cost of the light guide plate can be reduced by replacing only the mold for forming the light input portion 901b. ing.
[0004]
[Problems to be solved by the invention]
However, in the case of using the mold having the split mold structure described above, a step occurs at the mating portion of the molded light guide plate, and when the surface light emitting device is configured using the light guide plate, bright lines are formed at the step portion. There was a problem that occurred.
[0005]
Accordingly, an object of the present invention is to provide a method of manufacturing a light guide plate of a surface light emitting device that can substantially eliminate bright lines generated in the surface light emitting device even when manufactured using a mold having a split mold structure. To do.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a method for manufacturing a light guide plate of a surface light emitting device according to the present invention has a first main surface and a second main surface, and diffuses light input from a light emitting diode. In the method of manufacturing the light guide plate of the surface light emitting device including the light input portion and the surface light emitting portion that emits the light diffused by the light input portion from the first main surface,
A fixed block having a recess, a slide block corresponding to the surface light emitting portion having a first upper surface and slidably provided in the recess, and a second upper surface contacting the slide block on the fixed block A light input unit block corresponding to the light input unit, and a mold in which a cavity having a shape corresponding to the shape of the light guide plate is formed, the slide block and the light input unit block A mold manufacturing step for manufacturing the second upper surface so as to be higher than the first upper surface by a mold step when combined with the fixed block;
Injecting molten thermoplastic resin into the cavity, and
And shaped such step corresponding to the mold step only on the second major surface at the boundary between the light input portion and the surface-emitting portion is formed, the light input portion thinner than the surface-emitting unit It is characterized by forming.
According to the method of manufacturing the light guide plate according to the present invention configured as described above, the step is formed on the second main surface so that the surface light emitting unit side is higher. It is possible to suppress the generation of bright lines in the vicinity of the boundary between the light input part and the surface light emitting part.
[0007]
In the method of manufacturing the light guide plate of the surface light emitting device according to the present invention, the thermoplastic resin melted in the mold step and the cavity so that the step is 80 μm or less in order to effectively suppress the generation of bright lines . that set the molding pressure for injecting the resin.
Further, in the manufacturing method of the light guide plate of the surface light-emitting device according to the present invention, more effectively the step is 10μm or more in order to suppress the occurrence of bright lines, as will become 60μm or less, in the mold step and the cavity that you set the molding pressure for injecting the molten thermoplastic resin is more preferable.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments according to the present invention will be described below with reference to the drawings.
As shown in FIG. 1, the light guide plate 1 of the surface light-emitting device of the present embodiment has a first main surface 12 that is an emission surface and a second main surface 13 that is a reflection surface on which a reflector is provided. The light input unit 1b diffuses the light input from the light emitting diode, and the surface light emitting unit 1a emits the light diffused by the light input unit 1b from the first main surface 12.
In the light guide plate 1 of the present embodiment, the light input unit 1b is compared with the surface light emitting unit 1a so that the step 10 is formed at the boundary between the light input unit 1b and the surface light emitting unit 1a only on the second main surface 13. Thus, it is possible to suppress the generation of bright lines at the boundary between the light input unit 1b and the surface light emitting unit 1a when the surface light emitting device is configured using the light guide plate of the present embodiment. Yes.
That is, in the light guide plate 1 of the present invention, as shown in FIG. 1 and FIG. 2A (a cross-sectional view taken along line AA ′ in FIG. 1), the light input portion 1 b and the surface on the second main surface 13. The light input portion 1b is made thinner than the surface light emitting portion 1a so that a step is formed so that the light input portion 1b is lowered at the boundary with the light emitting portion 1a, and the light input portion 1b and the surface light emitting portion 1a are formed on the first main surface. No step is created at the boundary.
[0009]
In the light guide plate 1 according to the embodiment configured as described above, a step is provided on the second main surface so that the surface light emitting unit 1a side becomes higher. As shown by the arrows in FIG. 2A, the light is dispersed in the same direction and input to the surface light emitting unit 1a. As a result, the generation of bright lines can be suppressed.
On the other hand, as shown in FIG. 2B for comparison, when the step 110 is generated such that the light incident portion 101a is higher than the surface light emitting portion 101a on the second main surface, FIG. As shown by the arrow b), the light is concentrated and reflected directly above the step 110, and a strong bright line is generated near the boundary between the light input portion 101b and the surface light emitting portion 101a on the first main surface.
Further, in the second main surface of the light guide plate, a step is not generated at the boundary between the light input unit 101b and the surface light emitting unit 101a, that is, the height of the light input unit 101b and the surface light emitting unit 101a is the same. Even if the light guide plate is manufactured by injection molding, if a split mold that matches the mold at the boundary between the light input portion 101b and the surface light emitting portion 101a is adopted, a linear protrusion is formed at the portion where the mold is matched. Therefore, bright lines are observed when the surface light emitting device is configured using the light guide plate.
[0010]
Therefore, in the present invention, the step portion 10 on the second main surface 13 is formed such that at least the light incident portion 1b is lower than the surface light emitting portion 1a.
In the present invention, in order to effectively suppress the generation of bright lines, the step is preferably 80 μm or less, more preferably 10 μm or more and 60 μm or less, as will be described in detail in Examples described later. To do.
[0011]
Next, the manufacturing method of the light guide plate of this Embodiment is demonstrated.
The light guide plate 1 of the present embodiment is manufactured by injecting a molten thermoplastic resin into a cavity formed in a mold.
As shown in FIG. 3, a mold (middle mold 30) for molding the light guide plate 1 of the present embodiment includes a fixed block 31 having a concave portion 31 a and a slide slidably provided in the concave portion 31 a of the fixed block 31. The block 32 and the light input unit block 33 provided on the fixed block 31 so as to contact the front surface of the slide block 32 are formed, and a cavity 35 corresponding to the shape of the light guide plate 1 is formed by these three blocks. .
In the middle mold 30 in FIG. 3, a runner 33 b for pressing the resin into the light input portion block 33 is formed.
Further, below the slide block 32, a protrusion pin 34 for protruding the slide block 32 upward is provided.
[0012]
Here, as shown in FIG. 4B, the middle mold 30 for forming the light guide plate 1 according to the present embodiment fixes the slide block 32 to the concave portion 31a of the fixed block 31 at a predetermined position. When the light input unit block 33 and the slide block 32 are combined on 31, the sample upper surface 33 a of the light input unit block 33 is made higher than the upper surface 32 a of the slide block 32 by t.
The middle mold 30 configured as described above is fitted into the recess 42a of the lower mold 42 shown in FIG. As shown in FIG. 4A, the light guide plate 1 corresponding to the cavity 35 is formed.
[0013]
In this way, the mold for forming the light guide plate 1 is a split mold between the light input portion 1b and the surface light emitting portion 1a, and the sample upper surface 33a of the light input portion block 33 is higher than the upper surface 32a of the slide block 32. By producing the light guide plate 1 in such a manner, the light guide plate 1 having a step difference such that the light input portion 1b becomes lower at the boundary between the light input portion 1b and the surface light emitting portion 1a on the second main surface 13 can be produced.
[0014]
Next, a second main step at the mold step t between the sample upper surface 33a of the light input unit block 33 and the upper surface 32a of the slide block 32 and the boundary between the light input unit 1b and the surface light emitting unit 1a of the light guide plate 1 is used. The relationship with the surface level difference T will be described.
Even when the mold step t is constant, if the molding pressure (injection pressure) is changed, there is the following relationship with the step T of the light guide plate 1.
That is, when the mold step t is set to 5 μm, the injection speed is constant at about 18 mm / S, and the injection pressure is sequentially increased, as shown in Table 1, the step of the light guide plate 1 is approximately proportional to the pressure. Becomes bigger.
[0015]
Table 1

[0016]
Therefore, in the present embodiment, the step T of the second main surface at the boundary between the light input portion 1b and the surface light emitting portion 1a of the light guide plate 1 is different from the sample upper surface 33a of the mold light input portion block 33 and the slide block. It is set in consideration of the mold level difference t between the upper surface 32a of 32 and the molding conditions, particularly the molding pressure (injection pressure).
[0017]
In the present invention, suitable materials for the light guide plate 1 are acrylic and polycarbonate. Table 2 below shows the physical properties and molding shrinkage.
Table 2

[0018]
【Example】
Examples according to the present invention will be described below.
As an embodiment according to the present invention, the light guide plate according to the present invention is formed so that the light incident portion 1b is lower than the surface light emitting portion 1a on the second main surface 13, and has twelve different values of the level difference T. The light guide plate was produced using acrylic, and the luminance when the surface light emitting device was configured using the light guide plate was measured. The result is shown in the graph of FIG.
In FIG. 6, a light guide plate outside the scope of the present invention formed so that the light incident portion 1 b is higher than the surface light emitting portion 1 a on the second main surface 13 is manufactured as a comparative example, and out of the scope of the present invention. For comparison, the luminance when a surface light-emitting device is configured using the light guide plate is shown. In FIG. 6, a point indicated by an X mark in which the value of the step T is negative (minus) relates to the comparative example.
[0019]
As is clear from the results shown in FIG. 6, the light guide plate of the example according to the present invention can lower the brightness of the bright line than the light guide plate of the comparative example.
Further, as can be seen from the graph of FIG. 6, in the present invention, in order to effectively reduce the luminance of the bright line, the step T is preferably 80 μm or less, and more preferably set to 10 μm or more and 60 μm or less. preferable.
[0020]
【The invention's effect】
As described above, the light guide plate of the surface light-emitting device according to the present invention emits the light input from the light-emitting diode and the light diffused by the light input unit from the first main surface. The surface light emitting unit, and the light input unit has a step difference in the second main surface such that the light input unit side is lowered at the boundary between the light input unit and the surface light emitting unit. The light input from the light emitting diode is dispersed in the same direction at the stepped portion and input to the surface light emitting portion 1a, and the bright line near the boundary between the light input portion and the surface light emitting portion is formed. Generation can be suppressed.
Thus, according to the present invention, it is possible to provide a light guide plate of a surface light emitting device that can substantially eliminate bright lines generated in the surface light emitting device even when manufactured using a mold having a split mold structure. .
[Brief description of the drawings]
FIG. 1 is a perspective view showing a configuration of a light guide plate according to an embodiment of the present invention.
2A is a cross-sectional view of the light guide plate of FIG. 1, and FIG. 2B is a cross-sectional view of the light guide plate outside the scope of the present invention shown for comparison.
FIG. 3 is a perspective view of a medium size for manufacturing the light guide plate of the present embodiment.
4A is a cross-sectional view of the light guide plate of the embodiment, and FIG. 4B is a cross-sectional view of the middle size of FIG.
FIG. 5 is a perspective view of an upper mold and a lower mold of the embodiment.
FIG. 6 is a graph showing brightness of bright lines with respect to a step T according to an embodiment of the present invention.
FIG. 7 is a plan view showing a configuration of a general surface emitting device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Light guide plate, 1b Light input part, 1a Surface light emission part, 10 Level difference part, 12 1st main surface, 13 2nd main surface, 30 Medium size, 31 Fixed block, 31a Recessed part, 32 slide block, 33 Light input part Block, 33b Runner, 34 Extrusion pin, 35 Cavity, 41 Upper mold, 42 Lower mold.

Claims (3)

A surface light emission having a first main surface and a second main surface, and diffusing the light input from the light emitting diode, and emitting the light diffused by the light input portion from the first main surface In the manufacturing method of the light guide plate of the surface light emitting device comprising the part,
A fixed block having a recess, a slide block corresponding to the surface light emitting portion having a first upper surface and slidably provided in the recess, and a second upper surface contacting the slide block on the fixed block A light input unit block corresponding to the light input unit, and a mold in which a cavity having a shape corresponding to the shape of the light guide plate is formed, the slide block and the light input unit block A mold manufacturing step for manufacturing the second upper surface so as to be higher than the first upper surface by a mold step when combined with the fixed block;
Injecting molten thermoplastic resin into the cavity, and
And shaped such step corresponding to the mold step only on the second major surface at the boundary between the light input portion and the surface-emitting portion is formed, the light input portion thinner than the surface-emitting unit method for manufacturing a light guiding plate of the surface light-emitting device and forming. As the step is 80μm or less, the manufacturing method of the light guide plate of the surface light-emitting device according to claim 1 to set the molding pressure for injecting the thermoplastic resin melted in said mold step and the cavity. The step is 10μm or more, as will become 60μm or less, the production of the light guide plate of the surface light-emitting device according to claim 1 to set the molding pressure for injecting the thermoplastic resin melted in said mold step and the cavity Way .

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