JPH0720319A - Light transmitter and its manufacture - Google Patents

Abstract

PURPOSE:To reflect by scattering light in an arbitrary direction and with desired intensity without installing an optical system such as a mirror, etc., on a light transmission line by providing a clouding part which satisfies a specific condition on the light transmission line, and introducing the light as reflecting by scattering in the arbitrary direction different from the incident direction of incident light. CONSTITUTION:Assuming the forward scattering intensity and backward scattering intensity of a material which comprises a light transmitter as S1 and S2, respectively, the clouding part 6 provided with component distribution to satisfy relation S1<S2 is provided on the light transmission line, and the incident light can be introduced as reflecting by scattering in the arbitrary direction different from the incident direction. In other words, the crossing part of the light transmission line is constituted of a core 1 that is a transparent layer and the clouding part(scattering/reflecting part) 6. A light circuit plate of two layer structure is manufactured at a light transmitter core part forming part which forms the clouding part 6. In such constitution, the incident light 5 on the light circuit plate at an upper layer can be reflected sufficiently in four directions, and the light can be transmitted satisfactorily even to the light circuit plate on a lower layer. Also, a small light emitting/receiving built-in element is provided at the light circuit plate on the upper layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical transmission body utilizing a light scattering phenomenon having an angle dependence, and is used as a light guide body of a backlight unit used in various display devices such as liquid crystal displays and various lighting equipment, or The present invention relates to an optical component used in an optical transmission system.

[0002]

2. Description of the Related Art Conventionally, a light guide used for a liquid crystal display or the like and a light guide device for illuminating meters and the like have been disclosed in Japanese Patent Laid-Open No. 2-111922
As disclosed in the publication, the surface of the reflecting plate is curved or made uneven so that the reflected light is obtained so as to have a desired intensity when viewed from the front. Further, in order to control the transmission of light such as branching and coupling with an optical circuit element, there is disclosed in Japanese Patent Laid-Open No.
-63007, a method using the refractive index difference based on Snell's law as described in Japanese Patent Publication No. 63007, a mirror in the transmission line,
A method of installing an optical system such as a lens is known.

[0003]

In the above-mentioned prior art, the efficiency of the intensity of the emitted light in the light guide of the backlight section used in a liquid crystal display or the like is low with respect to the light source intensity, and practical brightness is obtained unless the light source intensity is increased. However, there is a problem in that the power consumption is increased because the intensity of the light source must be increased. In addition, there is a problem that, in the optical transmission body having an angle equal to or greater than the critical angle at which the light cannot be totally reflected, leakage of the light occurs when the transmission light is branched and the optical loss of the optical circuit increases. Therefore, the light transmission path (core) must be formed in a gentle shape, and it is small in size, such as being unable to reflect at a right angle or to form a core part with a small radius of curvature below a critical angle at which light cannot be totally reflected. Moreover, this method was unsuitable for the manufacturing process of an optical transmission body having a three-dimensional structure.
Furthermore, the method of installing an optical system such as a mirror and a lens in the transmission line has a problem that the number of times of surface reflection increases and thus depends largely on the accuracy of optical polishing of the end face, which complicates the process.

[0004]

DISCLOSURE OF THE INVENTION As a result of studying a method of efficiently diffusing and reflecting light in an arbitrary direction even at an angle equal to or less than a critical angle at which light cannot be totally reflected, the inventors of the present invention have found that an optical element such as a mirror is provided in a transmission body. The present invention has been accomplished by finding a method for efficiently performing diffuse reflection without installing a system. The gist of the present invention is as follows.

(1) When the forward scattering intensity of the substance forming the optical transmission medium is S1 and the backward scattering intensity is S2, at least one cloudy layer having a composition distribution satisfying the number 1 is provided in the optical transmission line. , An optical transmission body that guides light while scattering and reflecting the incident light in an arbitrary direction different from the incident direction.

[0006]

[Equation 1] S1 <S2 (Equation 1) (2) A copolymer in which the cloudy layer is composed of a plurality of polymerization-reactive organic monomers, or one polymerization-reactive organic monomer and The difference from the refractive index of the organic monomer polymer is 0.
An optical transmission body which is a polymer composed of at least one kind of substance of 01 or more, or a mixture of plural kinds of inorganic glasses having a difference in refractive index of 0.01 or more. (3) A manufacturing method by a two-color injection molding method in which both the transmission line and the cloudy layer of the optical transmission body are obtained by an injection molding method.

By providing the cloudy portion, it is possible to form a core portion having a small radius of curvature that cannot reflect light at a right angle or totally reflect light. Therefore, it is possible to miniaturize an optical circuit or achieve high integration by a multilayer structure. Becomes Further, it is possible to manufacture a light guide device which has a wide viewing angle and can obtain a reflected light with a uniform intensity or a reflected light intensity which is intentionally changed. It is also possible to mix a pigment in the cloudy layer, which is suitable for decorative purposes, night lights, guide lights and the like. The white turbid layer may be an organic substance or an inorganic glass as long as it satisfies the light scattering condition shown by the equation (1).

Known materials can be used as the polymerization-reactive organic monomer used as a raw material for the optical transmission medium of the present invention. Particularly, a methacrylic acid ester derivative and an acrylic acid ester derivative are preferable. For example, methyl methacrylate, ethyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2,2,2
-Trifluoroethyl methacrylate, 2,2,3,3
-Tetrafluoropropyl methacrylate, 2,2
3,3,4,4,5,5-octafluoropentyl methacrylate, glycidyl methacrylate, ethylene glycol dimethacrylate, hydroxyethyl methacrylate, phenyl methacrylate, stearyl methacrylate, propyl methacrylate, butyl methacrylate, dimethylaminoethyl methacrylate, tridecyl methacrylate and Acrylic ester, methyl-α
-Fluoroacrylate, trifluoroethyl-α-fluoroacrylate, pentafluoropropyl-α-fluoroacrylate, methyl-α-chloroacrylate and the like. In addition, polystyrene, polycarbonate,
A method in which a polymer having a large orientation birefringence such as polyarylate and its derivative is subjected to plastic deformation treatment such as stretching and then used is also effective.

[0009]

[Effect] Even if each of the raw material components is transparent, it may become opaque (white turbid) in the case of a mixture or compound of a plurality of types. Further, when the composition ratio of the raw material components exceeds a certain mixing ratio, it may become opaque (white turbid).
Even a single component is opaque (white turbid) depending on the molding conditions.
It may be. This is a phenomenon caused by the light scattering due to the difference in refractive index between the two phases due to the phase separation of each raw material component in the order of wavelength. For a single component,
It is due to the fluctuation of the refractive index due to the fluctuation of the density due to the change of the aggregation structure. The light scattering intensity in these cases is S1 <S2, where S1 is the forward scattering intensity and S2 is the back scattering intensity.
Has become. Therefore, if a white turbid layer having a large backscattering intensity is formed in a portion to be reflected, the white turbid layer has a scattering reflection effect. Further, if this cloudy layer is formed with a compositional distribution, a transparent region with a large forward scattering and a cloudy region with a large backscattering will occur in a certain composition range, and the reflected light intensity can be controlled arbitrarily. Therefore, it is possible to take out the light guide of the backlight unit of the liquid crystal display or the reflected light component of 90 degrees or more, so that the light can be propagated in the required vertical direction in the optical circuit board or the like. .

[0010]

EXAMPLES The present invention will be described in detail below with reference to examples.

(Embodiment 1) 2,2 as M1 monomer
3,3-tetrafluoropropyl methacrylate, M
M1 / M2 = 2 with methyl methacrylate as 2 monomers
1.5 (by weight ratio), a hemispherical acrylic polymer is installed at the intersection of the optical transmission body cores forming the cloudy layer, and 1.5 ×
A 1.5 mm core portion was cast-polymerized at 85 ° C. to prepare an optical circuit board having a two-layer structure of 10 × 15 cm as shown in FIG.
The branched portion after curing had a hemispherical cloudy layer, and in the light scattering loss measurement result, the backscattering intensity S2 was larger than the forward scattering intensity S1. The incident light was equally split into four directions of up, down, left and right. Benzoyl peroxide was added as a polymerization initiator in a mixing monomer ratio of 0.3% by weight. The substrate 2 made of poly (4-methylpentene-1) (TPX resin) is manufactured by an injection molding method and also serves as a clad. Light is transmitted through the core 1. Transmission wavelength is 660nm
The red LED of was used. The intersecting portion of the light transmitting portion has a structure as shown in FIG. 2, and is composed of a core 1 which is a transparent layer and a cloudy portion (scattering / reflecting portion) 6. Light 5 incident on the upper optical circuit board was sufficiently reflected in four directions, and the light was well transmitted to the lower optical circuit board. The optical circuit board in the upper layer has a small light emitting / receiving unit built-in element 3 in the middle thereof. Light was emitted from the connector 4 for connecting the optical fiber using the optical fiber on all the emission end faces. All emitted light is light /
It was possible to operate a motor connected via an electrical (O / E) converter and an electrical / optical (E / O) converter.

Comparative Example 1 In the same manner as in Example 1, a homopolymer methyl methacrylate polymer was used for the core,
An optical circuit board having the same structure was manufactured. Most of the incident light leaked at the intersection, and the system using this circuit board was inoperable.

(Example 2) 2,2 as M1 monomer
3,3-tetrafluoropropyl methacrylate, M
2,2,3,3,4,4,5,5-octafluoropentyl methacrylate as 2 monomer M1 / M2 = 2 /
Using 1 (weight ratio), a wedge-shaped cloudy polymer having a maximum thickness of 3 mm and a size of 10 × 15 cm as viewed from the front was cast-polymerized at 85 ° C. As a polymerization initiator, 0.3% by weight of benzoyl peroxide was added in a mixed monomer ratio. According to the light scattering loss measurement result, the backscattering intensity S2 of this cloudy layer was larger than the forward scattering intensity S1. As a polymer for the transmission line, methyl methacrylate was polymerized in the same manner to obtain a wedge-shaped polymer having the same shape. These two wedge-shaped polymers were attached to each other as shown in FIG. 3, and the light of the fluorescent lamp was incident from the side. A white fluorescent lamp was used as the light source 7, and light was incident from one end by a reflecting mirror. The light emitted surface-wise with a uniform intensity, and unevenness in light emission depending on the location was hardly confirmed.

(Comparative Example 2) A light source built-in type light guide similar to that of Example 3 was produced by using a mirror for the reflection part and polymethylmethacrylate for the light guide part. The closer to the light source section, the higher the reflected light intensity was, and the uniform intensity distribution as in Example 3 was not obtained.

(Example 3) Benzyl methacrylate (M1; polymer refractive index: 1.5) as a polymerization-reactive monomer
6) is a wedge shape with a maximum thickness of 3 mm and a size of 10 × 15 cm when viewed from the front, using silicone oil (M2) having a refractive index of 1.50 as a light scattering component, M1 / M2 = 20/1 (weight ratio). The cloudy polymer was obtained by casting polymerization at 85 ° C. As a polymerization initiator, 0.3% by weight of benzoyl peroxide was added in a mixed monomer ratio. According to the light scattering loss measurement result, the backscattering intensity S2 of this cloudy layer was larger than the forward scattering intensity S1. As a polymer for the transmission line, methyl methacrylate was polymerized in the same manner to obtain a wedge-shaped polymer having the same shape. These two wedge-shaped polymers were attached to each other as shown in FIG. 3, and the light of the fluorescent lamp was incident from the side.
A white fluorescent lamp was used as the light source 7, and light was incident from one end by a reflecting mirror. The light emitted surface-wise with a uniform intensity, and unevenness in light emission depending on the location was hardly confirmed.

Example 4 As a polymerization-reactive monomer,
2,3,3-tetrafluoropropyl methacrylate
(M1; refractive index of polymer: 1.42) was used for removing the polymerization inhibitor after washing, without drying, and the maximum thickness was 3 mm.
A wedge-shaped cloudy polymer having a size of 10 × 15 cm as viewed from the front was obtained by casting polymerization at 90 ° C. As the polymerization initiator, benzoyl peroxide was added in an amount of 0.3% by weight in terms of monomer ratio. The water content of this monomer was 1.8% by weight in terms of monomer ratio as a result of water determination. According to the light scattering loss measurement result, the backscattering intensity S2 of this cloudy layer was larger than the forward scattering intensity S1. As a polymer for the transmission line, methyl methacrylate was polymerized in the same manner to obtain a wedge-shaped polymer having the same shape. These two wedge-shaped polymers were attached to each other as shown in FIG. 3, and the light of the fluorescent lamp was incident from the side. A white fluorescent lamp was used as the light source 7, and light was incident from one end by a reflecting mirror. The light emitted surface-wise with a uniform intensity, and unevenness in light emission depending on the location was hardly confirmed.

(Example 5) Two kinds of glass mixtures (G1 / G) having a refractive index of 1.75 (G1) and 1.55 (G2).
2 = 10/1 (weight ratio)) was used to obtain a wedge-shaped cloudy glass having a maximum thickness of 3 mm and a size of 10 × 15 cm as viewed from the front. According to the light scattering loss measurement result, the backscattering intensity S2 of this cloudy layer was larger than the forward scattering intensity S1. As a polymer for the transmission line, methyl methacrylate was polymerized in the same manner to obtain a wedge-shaped polymer having the same shape. These two wedge shapes were attached to each other as shown in FIG. 3, and the light of the fluorescent lamp was incident from the side surface. A white fluorescent lamp was used as the light source 7, and light was incident from one end by a reflecting mirror. The light emitted surface-wise with a uniform intensity, and unevenness in light emission depending on the location was hardly confirmed.

(Embodiment 6) 10 × 25 as shown in FIG.
A cm display panel for the instrument panel was produced. An acrylic polymer chip made by adding Rhodamine 6G dye in an amount of 0.05% by weight was installed in the bent portion of the light transmission body connected to the portion of the display portion where the color-coded display was desired, and 2,2,3,3-tetra-methyl was prepared as the M1 monomer. Fluoropropyl methacrylate was cast-polymerized at 85 ° C. using methyl methacrylate M1 / M2 = 2/1 (weight ratio) as M2 monomer. The bent part after curing is a cloudy red layer, and in the light scattering loss measurement result,
The backscattering intensity S2 was larger than the forward scattering intensity S1. Benzoyl peroxide was added as a polymerization initiator in a mixing monomer ratio of 0.3% by weight. The light source 7 is 1.
A 5V miniature bulb was used. Despite the light source of a miniature electric bulb of only 1.5 V, a good red display with uniform emission intensity was obtained.

(Embodiment 7) Outer diameter 20 mm as shown in FIG.
A rod-shaped lighting device having a length of 50 cm was manufactured. 0.3% by weight of benzoyl peroxide as a polymerization initiator was added to a mold holding an acrylic rod having a diameter of 5 mm, and M2 monomers were 2,2,3,3-tetrafluoropropyl methacrylate and M2 monomers. As a mixed monomer in which M1 / M2 = 2/1 (weight ratio) was used as a mixture, and cast polymerization was performed at 85 ° C. The light scattering loss measurement result of the white turbid part in the center after curing shows that the forward scattering intensity S
The backscattering intensity S2 was larger than 1. Sunlight was used as the light source, and sunlight was incident from one rod end surface using the plastic optical fiber bundle (10 pieces) 9. Due to the sunlight, there was no heat generation in the light emitting part, and an illumination device with uniform light emission was obtained.

(Embodiment 8) FIG. 6 shows a manufacturing process of a planar light guide by two-color injection molding. First, as shown in FIG. 6 (a) for forming a transmission line, polymethylmethacrylate is injected into a wedge-shaped mold using an injection molding machine at an injection temperature of 2
After injection and curing at 30 ° C., the molded product was taken out of the mold.
After embedding the molded product in a rectangular mold as shown in FIG. 6 (b) again, as an M1 monomer for forming a cloudy layer 2,
2,3,3-tetrafluoropropyl methacrylate,
M1 / M2 = methyl methacrylate as M2 monomer
Polymer pellets polymerized using 2/1 (weight ratio) were injected at an injection temperature of 240 ° C, and the thickness was 3 mm and the size was 10 when viewed from the front.
A planar light guide having a size of 15 cm as shown in FIG. 6C was obtained. Using the method shown in FIG. 3 of Example 2, the light of the fluorescent lamp was made incident on the obtained planar light guide. Light source 7
A white fluorescent lamp was used as the light source, and light was incident from one end by a reflecting mirror. The light emitted surface-wise with a uniform intensity, and unevenness in light emission depending on the location was hardly confirmed.

(Example 9) A bisphenol-A type polycarbonate was used as a polymer to partially remove
After heating to 0 ℃, stretched to initial ratio 1.5 times, maximum thickness 3
A wedge-shaped cloudy polymer having a size of 10 × 15 cm as viewed from the front was prepared by cutting. According to the light scattering loss measurement result, the backscattering intensity S2 of this cloudy layer was larger than the forward scattering intensity S1. Methylmethacrylate was cast-polymerized as a polymer for the transmission line to obtain a wedge-shaped polymer of the same shape. These two wedge-shaped polymers were attached to each other as shown in FIG. 3, and the light of the fluorescent lamp was incident from the side. Light source 7
A white fluorescent lamp was used as the light source, and light was incident from one end by a reflecting mirror. The light emitted surface-wise with a uniform intensity, and unevenness in light emission depending on the location was hardly confirmed.

[0022]

According to the present invention, it is possible to obtain an optical transmission body, a light guide body and various lighting equipments capable of scattering and reflecting light in desired directions with desired intensity.

[Brief description of drawings]

FIG. 1 is a perspective view of a two-layer optical circuit board.

FIG. 2 is a perspective view of a branch portion of a two-layer optical circuit board.

FIG. 3 is a sectional view of a light guide with a built-in light source.

FIG. 4 is a plan view of an instrument panel display unit.

FIG. 5 is a perspective view of a rod-shaped lighting device.

FIG. 6 is an explanatory view showing a manufacturing process of a planar light guide body by two-color injection molding.

[Explanation of symbols]

1 ... Core (optical transmission unit), 2 ... Substrate (also clad), 3 ...
Elements with built-in light receiving and emitting parts, 4 ... Optical fiber insertion connector, 5 ...
Incident light, 6 ... White turbid part (scattering / reflecting part), 7 ... Light source, 8 ... Reflecting mirror, 9 ... Plastic optical fiber bundle, 10 ... Mold.

Claims (9)

[Claims] 1. A white turbid layer having a composition distribution satisfying S1 <S2 at least at one position in the optical transmission path, where S1 is the forward scattering intensity of the substance forming the optical transmission medium and S2 is the back scattering intensity. An optical transmission body, which is provided and guides light while scattering and reflecting incident light in an arbitrary direction different from the incident direction. 2. The optical transmission body according to claim 1, wherein the cloudy layer is a copolymer composed of a plurality of types of polymerization-reactive organic monomers. 3. The at least one kind according to claim 1, wherein the cloudy layer has a difference in refractive index of 0.01 or more from one kind of polymerization-reactive organic monomer and a polymer of the organic monomer. An optical transmission material that is a polymer composed of the above substances. 4. The cloudy layer according to claim 1, wherein the cloudy layer consists essentially of one type of polymer, and S1 is formed by birefringence associated with orientation.
An optical transmission body having a composition distribution satisfying <S2. 5. The optical transmission body according to claim 1, wherein the cloudy layer is made of a mixture of a plurality of kinds of inorganic glasses having a refractive index difference of 0.01 or more. 6. The liquid crystal display device according to claim 1, further comprising a light source that is provided on a side surface of the light guide plate and irradiates light into the light guide plate body, wherein the light guide plate is S.
1 <S2 is satisfied, and S2 increases as the distance from the light source increases.
An optical transmission medium having a composition distribution such that 7. The meter according to claim 1, further comprising a back lighting device, the meter being provided on a side of the light guide plate and irradiating light into a body of the light guide plate, wherein the light guide plate is S1 <S.
An optical transmission medium that satisfies the requirement 2 and has a composition distribution in which S2 increases as the distance from the light source increases. 8. The optical transmission medium according to claim 1, wherein a dye is mixed in the cloudy layer in an amount of 20% by weight or less with respect to a monomer as a raw material. 9. A white turbid layer having a composition distribution satisfying at least S1 <S2 in the optical transmission line, where S1 is the forward scattering intensity and S2 is the back scattering intensity of the substance forming the optical transmission medium. In a method for manufacturing an optical transmission body that guides light while scattering and reflecting the incident light in an arbitrary direction different from the incident direction, a step of injecting and curing a resin into a mold for forming a transmission path, and a molded product are described. After the step of taking out from the mold, the molded product is embedded in a mold for forming an optical transmission body, a resin satisfying S1 <S2 for forming a cloudy layer is a resin for obtaining the molded product. The method for producing an optical transmission medium, comprising the steps of injecting at a molding temperature not higher than the injection temperature to form an optical transmission medium, and taking out a molded product of the optical transmission medium including a transmission line and a cloudy layer.