KR20140106434A - Light guide film, ultra-thin liquid crystal backlight unit and portable computer - Google Patents

Abstract

The objective of the present invention is to provide a light guide film capable of reducing the thickness and preventing deterioration of the brightness, an ultra-thin liquid crystal backlight unit including the light guide film, and a portable computer. The light guide film given in the present invention has an average thickness equal to or less than 600 μm, and the main component is aromatic-series polycarbonate resin. To aromatic-series polycarbonate resin of 100 parts by weight, an antioxidant of 0.01 - 0.1 parts by weight is added. The weight-average molecular weight of the aromatic-series polycarbonate resin is 2.0×104 - 5.0×104. The ratio of the weight-average molecular weight to the number average molecular weight of the polystyrene-converted aromatic-series polycarbonate resin, measured by gel permeation chromatography, is 1.0 - 2.5. The light guide film is molded through extrusion.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a light guide film, an ultra-thin liquid crystal backlight unit, and a portable computer.

The present invention relates to a light guide film, an ultra-thin liquid crystal backlight unit, and a portable computer.

BACKGROUND ART [0002] A liquid crystal display device has a backlight system in which a liquid crystal layer is illuminated from the back side to emit light, and a backlight unit such as an edge light type or direct under type is provided on the lower surface side of the liquid crystal layer. 5, the edge light type backlight unit 110 generally includes a top plate 116 located on the most rear surface of the liquid crystal display unit, a reflective sheet 115 arranged on the surface of the top plate 116 A light guide plate 111 arranged on the surface of the reflective sheet 115 and a light source 117 for emitting light toward the end face of the light guide plate 111 (Japanese Patent Laid-Open No. 2010-177130 ). 5, the light irradiated by the light source 117 and incident on the light guide plate 111 propagates in the light guide plate 111. In the edge light type backlight unit 110 of FIG. A part of the propagated light is emitted from the back surface of the light guide plate 111, is reflected by the reflection sheet 115, and is incident on the light guide plate 111 again.

A portable computer having such a liquid crystal display part is required to be thinner and lighter in order to improve portability and convenience, and accordingly, a liquid crystal display part is also required to be thinner. Particularly, in an ultra-thin portable computer having a maximum thickness of 21 mm or less of a housing called an Ultrabook (registered trademark), it is desired that the thickness of the liquid crystal display part is about 4 mm to 5 mm. In the edge light type backlight unit put in the liquid crystal display part, Is required.

The edge light type backlight unit 210 of such an ultra-thin portable computer has a reflective sheet 115 arranged on the back surface of the light guide plate 111 as shown in Fig. 5, Similarly, it has been proposed to reduce the thickness by not using the reflective sheet 115 as shown in Fig. The edge light type backlight unit 210 shown in Fig. 6 includes a top plate 216 made of metal, a light guide plate 211 laminated on the surface of the top plate 216, And the surface of the top plate 216 is polished to have a function as a reflecting surface 216a. The light emitted from the light source 217 and incident on the light guide plate 211 is propagated into the light guide plate 211. A part of the propagated light is emitted from the back surface of the light guide plate 211, And is incident on the light guide plate 211 again. 6, the edge surface of the top plate 216 is a reflecting surface 216a, so that the reflecting surface 216a of the edge light type backlight unit 210 shown in FIG. 6 replaces the reflecting sheet 115 of FIG. Therefore, the edge light type backlight unit 210 does not require the reflective sheet 115, and the liquid crystal display unit is thinned.

In the edge-light type backlight unit of such an ultra-thin portable computer, since the thickness of the liquid crystal display part is about the above, the average thickness of the light guide film is required to be 600 占 퐉 or less.

On the other hand, a conventional light guide film is produced by an injection molding method using a polycarbonate resin, an acrylic resin, or the like as a main component. However, according to such a conventional injection molding method, it has been extremely difficult to produce a thin light guide film corresponding to a large screen such as a laptop computer.

It is also conceivable to produce a light guide film by an extrusion molding method using the above-mentioned conventional resin. In this case, however, in the case of occurrence of turbidity at the time of sheet molding, scratches due to lack of scratch resistance, There is a problem that luminance is lowered due to occurrence of moiré caused by the above.

Japanese Patent Application Laid-Open No. 2010-177130

It is an object of the present invention to provide a light guide film capable of coping with a large screen like a laptop computer and promoting thinning and preventing a decrease in luminance. Another object of the present invention is to provide an ultra-thin liquid crystal backlight unit and a portable computer in which luminance deviation is suppressed and thinning is achieved.

In order to solve the above problems, the light guide film according to the present invention,

A light guide film for an ultra-thin liquid crystal backlight unit having an average thickness of 600 占 퐉 or less which emits light beams incident from an end face substantially uniformly from a surface,

An aromatic polycarbonate resin as a main component and an antioxidant in an amount of 0.01 part by mass or more and 0.1 part by mass or less based on 100 parts by mass of the aromatic polycarbonate resin,

Wherein the aromatic polycarbonate resin has a weight average molecular weight of from 2.0 x 10 ⁴ to 5.0 x 10 ⁴ ,

The ratio (Mw / Mn) of the weight average molecular weight to the number average molecular weight in terms of polystyrene of the aromatic polycarbonate resin measured by gel permeation chromatography is 1.0 or more and 2.5 or less,

And is molded by an extrusion molding method.

The light guide film preferably has a weight average molecular weight of the aromatic polycarbonate resin and a ratio (Mw / Mn) of the weight average molecular weight to the number average molecular weight of the aromatic polycarbonate resin in terms of polystyrene measured by gel permeation chromatography, , The light transmittance and the mechanical strength after molding can be increased while improving the extrusion moldability. Therefore, the light guide film has an average thickness within the above-mentioned range, and can also cope with a large screen. Further, by containing the antioxidant in the above ratio, the light guide film of the light guide film can prevent the yellowing at the time of molding and prevent the luminance from lowering. Further, since the light guide film is mainly composed of an aromatic polycarbonate resin, the light guide film has less absorbability than the acrylic resin, and the dimensional stability is improved.

Art light guide film is good when the melt volume flow rate (300 ℃, 1.2kg load) in the aromatic polycarbonate resin is 15cm ³ / 10min at least 80cm ³ / 10min or less. As a result, extrusion moldability can be improved.

The light guide film may have a branching ratio of the aromatic polycarbonate resin of 0.5 mol% or more and 1.5 mol% or less. As a result, it is possible to prevent the lowering of the melt tension and improve the extrusion moldability, as well as to increase the transparency after molding and to improve the light transmittance.

The light guide film may contain a polystyrene resin having a weight average molecular weight of 1000 to 10000, which is contained in an amount of 0.1 part by mass or more and 3 parts by mass or less based on 100 parts by mass of the aromatic polycarbonate resin. As a result, the light transmittance can be improved.

The light guide film may have a spectral light transmittance of 65% or more at a wavelength of 300 nm. Thus, the light guide property can be improved and the brightness can be improved.

The light guide film may contain a thermoplastic polyacrylic resin containing 0.01 parts by mass or more and 1 part by mass or less based on 100 parts by mass of the aromatic polycarbonate resin. As a result, the spectral light transmittance can be improved.

The light guide film may have a diffusion pattern on the back side. Thus, the emission characteristics of the light beams emitted from the surface of the light guide film can be adjusted to improve the surface uniformity.

The light guide film may be formed of a plurality of light scattering parts in which the diffusion pattern is developed by laser irradiation. This makes it possible to easily and reliably form a desired diffusion pattern. In addition, when a diffusion pattern is formed by such a method, it is not necessary to provide a convex portion or the like on the back surface of the light guide film, so that thinning can be promoted.

In order to solve the above-mentioned problems, an ultra-thin liquid crystal backlight unit according to the present invention comprises a top plate whose surface is formed on a reflective surface and located on the backmost surface of the liquid crystal display unit, the light guide film having the above- And a light source that irradiates light to the end surface of the light guide film.

Since the ultra-thin liquid crystal backlight unit is provided with the light guide film having improved light transmittance and mechanical strength as well as improved extrusion moldability, the thin liquid crystal backlight unit can cope with a large screen while promoting thinness. In addition, since the ultra-thin liquid crystal backlight unit does not use a conventional reflective sheet, the thin type liquid crystal backlight unit is further promoted.

The ultrathin liquid crystal backlight unit may be a top plate made of metal, and the arithmetic mean roughness (Ra) of the reflecting surface may be 0.2 탆 or less. Since the top plate of the ultra thin liquid crystal backlight unit is made of metal, the reflecting surface can be easily and surely formed by polishing the surface. When the arithmetic mean roughness of the reflecting surface is 0.2 탆 or less, the light emitted from the back surface of the light guide film is likely to be regularly reflected at the reflecting surface, and the light utilization efficiency is high. Moreover, It is difficult to damage the back surface of the light guide film.

In addition, the ultra-thin liquid crystal backlight unit according to the present invention, which is performed to solve the above-described problems, includes a top plate positioned on the backmost surface of the liquid crystal display unit, a reflective sheet laminated on the surface of the top plate, A light guide film and a light source for irradiating light to an end surface of the light guide film. Such an ultra-thin liquid crystal backlight unit is also provided with the light guide film of which the light transmittance and the mechanical strength are improved by this structure, so that the ultra thin liquid crystal backlight unit can cope with a large screen while promoting thinning.

In order to solve the above-described problems, the portable computer according to the present invention includes the liquid crystal display unit with the ultra-thin liquid crystal backlight unit constructed as described above.

This portable computer has the above-described ultra-thin liquid crystal backlight unit having the above-described configuration, and thus has the advantages described above. Further, when the top surface of the top plate functions as a reflecting surface, the portable computer of the present invention does not require a conventional reflecting sheet, thereby further promoting the thinning.

The " surface " means the display surface side of the liquid crystal display part. Means the top side and means the opposite side of the display surface of the liquid crystal display part. The " average thickness " is an average value of values measured by the method A-2 of 5.1.2 prescribed in JIS-K-7130. The "weight average molecular weight" (Mw) refers to the value in terms of polystyrene measured by gel permeation chromatography (GPC) using tetrahydrofuran (THF). &Quot; Melt volume flow rate (300 DEG C, 1.2kg load) " The " spectral light transmittance at a wavelength of 300 nm " is in a visible-UV spectral spectrum measured at a thickness of 400 m. The "arithmetic mean roughness (Ra)" is a value of cut-off lambda c of 2.5 mm and an evaluation length of 12.5 mm in accordance with JIS B0601-1994.

INDUSTRIAL APPLICABILITY As described above, the light guide film of the present invention can cope with a large screen like a laptop computer, can promote thinning, and can prevent a decrease in brightness. Further, the ultra-thin liquid crystal backlight unit and the portable computer of the present invention are promoted to be thinned, and the luminance is prevented from being lowered.

Fig. 1 is a schematic perspective view of a laptop computer according to an embodiment of the present invention, wherein (A) shows a state in which the liquid crystal display part is opened, and Fig. 2 (B) shows a state in which the liquid crystal display part is closed.
Fig. 2 is a schematic sectional view showing an ultra-thin liquid crystal backlight unit of the laptop computer of Fig. 1;
Fig. 3 is a schematic enlarged view showing a device for manufacturing a light guide film of the ultra-thin liquid crystal backlight unit of Fig. 2; Fig.
4 is a schematic cross-sectional view showing an ultra-thin liquid crystal backlight unit according to a mode different from that of the ultra-thin liquid crystal backlight unit of FIG.
5 is a schematic sectional view showing a conventional edge light type backlight unit.
6 is a schematic cross-sectional view showing a conventional edge light type backlight unit according to a mode different from that of FIG.

(Mode for carrying out the invention)

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings appropriately.

[First Embodiment]

<Laptop computer (1)>

The laptop computer 1 shown in Fig. 1 has an operation unit 2 and a liquid crystal display unit 3 connected to the operation unit 2 so as to be rotatable (openable and closable). The laptop computer 1 has a structure in which the thickness of the housing (the casing that entirely accommodates the components of the laptop computer 1) (the thickest part (when the liquid crystal display part 3 is closed)) is 21 mm or less, Trademark) (hereinafter sometimes referred to as &quot; ultra-thin computer 1 &quot;).

The liquid crystal display part 3 of the ultra-thin computer 1 includes a liquid crystal panel 4 and an edge light type ultra-thin liquid crystal backlight unit 11 (hereinafter referred to as &quot; backlight &quot;) for irradiating light from the back side toward the liquid crystal panel 4 Quot; unit 11 &quot;). The liquid crystal panel 4 is held around the back surface, the side surface, and the surface by the casing 6 for the liquid crystal display part of the housing. The casing 6 for the liquid crystal display part includes a top plate 16 arranged on the back surface (and back surface) of the liquid crystal panel 4 and a top plate 16 arranged on the surface side of the surface of the liquid crystal panel 4 And a member (7). The housing of the ultra-thin computer 1 is rotatably installed in the casing 6 for the liquid crystal display part and the casing 6 for the liquid crystal display part via the hinge part 8 and is provided with a central processing unit (ultra low voltage CPU) And a casing (9) for the operating unit in which the casing (9) is embedded.

The thickness of the liquid crystal display part 3 is not particularly limited as long as the thickness of the housing is in a desired range. However, the upper limit of the thickness of the liquid crystal display part 3 is preferably 7 mm, more preferably 6 mm, Do. On the other hand, the lower limit of the thickness of the liquid crystal display part 3 is preferably 2 mm, more preferably 3 mm, and further preferably 4 mm. If the thickness of the liquid crystal display part 3 exceeds the upper limit, there is a fear that it is difficult to follow the request for thinning of the ultra-thin computer 1. If the thickness of the liquid crystal display part 3 is less than the above lower limit, there is a fear that the strength of the liquid crystal display part 3 is lowered, the brightness is lowered, and the like.

<Backlight unit 11>

2, the backlight unit 11 includes a light guide film 12, a reflection sheet 13 arranged on the back surface of the light guide film 12, And a light source 17 for irradiating the light guide film 12 with light.

(Light guide film 12)

The light guide film 12 emits a light beam incident from the end surface almost uniformly from the surface. The light guide film 12 is formed in a substantially rectangular shape in plan view and is formed in a substantially uniform plate shape (non-wedge shape). A diffusion pattern (14) is formed on the back surface of the light guide film (12).

The average thickness of the light guide film 12 is 600 占 퐉 or less. The upper limit of the average thickness of the light guide film 12 is more preferably 550 탆, and further preferably 400 탆. On the other hand, the lower limit of the average thickness of the light guide film 12 is preferably 100 占 퐉, more preferably 150 占 퐉, and further preferably 200 占 퐉. If the average thickness exceeds the upper limit, there is a possibility that the backlight unit 11 expected to be thin in the ultra-thin computer 1 may not be able to conform to the demand for thinning. If the average thickness is less than the lower limit described above, there is a possibility that the light guide film 12 may have insufficient strength, and the light from the light source 17 may not sufficiently enter the light guide film 12.

Since the light guide film 12 needs to transmit light rays, it is formed transparent, particularly colorless and transparent. The light guide film 12 is formed of a polycarbonate resin as a main component. The light guide film 12 is made of a polycarbonate-based resin as a main component, thereby increasing the transparency and reducing the light damage. Furthermore, since the polycarbonate resin has heat resistance, deterioration or the like is hardly caused by heat generation of the light source 17. In addition, the polycarbonate resin has less absorbability than the acrylic resin, and therefore has high dimensional stability.

The polycarbonate resin is not particularly limited and may be either a linear polycarbonate resin or a branched polycarbonate resin or may be a polycarbonate resin containing both a linear polycarbonate resin and a branched polycarbonate resin do. As the polycarbonate-based resin, an aromatic polycarbonate-based resin excellent in transparency, impact resistance, flame retardancy, dimensional stability and the like is preferable.

The aromatic polycarbonate resin is not particularly limited and may be used alone or in combination of two or more. The aromatic polycarbonate resin may be a resin having a structure represented by the general formula - (- O - X 1 - OC (═O) -) - (wherein X ¹ is generally a hydrocarbon but a hetero atom, Which is a polymer of a basic structure having a carbonic ester bond. The aromatic polycarbonate resin refers to a polycarbonate resin in which the carbon directly bonded to the carbonic ester bond is an aromatic carbon.

Examples of the aromatic polycarbonate resin include an aromatic polycarbonate polymer of a thermoplastic resin obtained by reacting an aromatic dihydroxy compound with a carbonate precursor. In addition to the dihydroxy compound and the carbonate precursor, a polyhydroxy compound or the like may be reacted. Further, a method of using carbon dioxide as the carbonate precursor and reacting with cyclic ether may be employed. The aromatic polycarbonate polymer may be a homopolymer composed of only one kind of repeating unit or a copolymer having two or more kinds of repeating units. Such a copolymer is not particularly limited, and is selected from various copolymerization forms such as a random copolymer and a block copolymer.

Examples of the aromatic dihydroxy compound used as a raw material of the aromatic polycarbonate resin include 1,2-dihydroxybenzene, 1,3-dihydroxybenzene, 1,4-dihydroxybenzene and the like Dihydroxybenzenes; Bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) methane, 1,1- (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) butane, 2,2- Bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxy-3-bromophenyl) propane, Bis (4-hydroxy-3,5-tetramethylphenyl) propane, 2,2-bis Bis (hydroxyaryl) alkanes such as tetrachlorophenyl) propane and 2,2-bis (4-hydroxy-3,5-tetrabromophenyl) propane; 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1-bis (4-hydroxyphenyl) cyclohexane, Bis (hydroxyaryl) cycloalkanes such as cyclohexane and 1,1-bis (4-hydroxyphenyl) -3-tert-butyl-cyclohexane; Dihydroxyaryl ethers such as 4,4'-dihydroxyphenyl ether and 4,4'-dihydroxy-3,3'-dimethylphenyl ether; Dihydroxydialyl sulfides such as 4,4'-dihydroxydiphenyl sulfide and 4,4'-dihydroxy-3,3'-dimethyl diphenyl sulfide; Dihydroxydialylsulfoxides such as 4,4'-dihydroxydiphenyl sulfoxide and 4,4'-dihydroxy-3,3'-dimethyl diphenyl sulfoxide; Dihydroxydiarylsulfone such as 4,4'-dihydroxydiphenyl sulfone and 4,4'-dihydroxy-3,3'-dimethyl diphenyl sulfone; And dihydroxydiphenyls such as 4,4'-dihydroxydiphenyl.

Among them, the aromatic dihydroxy compound is preferably a bis (hydroxyaryl) alkane. Among the above bis (hydroxyaryl) alkanes, bis (4-hydroxyphenyl) alkanes are preferable, and 2,2-bis (4-hydroxyphenyl) propane (bisphenol A) is particularly preferable. As the aromatic dihydroxy compound, only one type may be used alone, or two or more types may be used in combination.

Examples of the carbonate precursor used as a raw material for the aromatic polycarbonate resin include carbonyl halide, carbonate ester and the like.

Examples of the carbonyl halide include phosgene; A bischloroformate compound of a dihydroxy compound, and a haloformate such as a monochloroformate compound of a dihydroxy compound.

Examples of the carbonate ester include diaryl carbonates such as diphenyl carbonate and ditolyl carbonate; Dialkyl carbonates such as dimethyl carbonate and diethyl carbonate; A bicarbonate of a dihydroxy compound, a monocarbonate of a dihydroxy compound, and a carbonate of a dihydroxy compound such as a cyclic carbonate.

The carbonate precursor may be used alone, or two or more of them may be used in combination.

The method for producing the aromatic polycarbonate resin is not particularly limited, and known methods such as an interface polymerization method, a melt transesterification method, a pyridine method, a ring-opening polymerization method of a cyclic carbonate compound, and a solid-phase ester exchange method of a prepolymer can be mentioned.

In the production of the aromatic polycarbonate resin, a branching agent may be used if necessary. Such branching agents include, for example, 1,1,1-tris (4-hydroxyphenyl) ethane; tris (4-hydroxyphenyl) -1,3,5-triisopropylbenzene, 1- [alpha -methyl- alpha - (4'-hydroxyphenyl) ethyl] -4- [? ',?' - bis (4 "-hydroxyphenyl) ethyl] benzene; Fluoroglycine, trimellitic acid, and isatin bis (o-cresol).

The branching rate of the aromatic polycarbonate resin is not particularly limited, but is preferably 0.5 mol% or more and 1.5 mol% or less. The upper limit of the partition ratio of the aromatic polycarbonate resin is more preferably 1.3 mol%, further preferably 1.2 mol%. The lower limit of the partition ratio of the aromatic polycarbonate resin is more preferably 0.7 mol%, further preferably 0.8 mol%. When the branching ratio of the aromatic polycarbonate resin exceeds the upper limit, the impact resistance and transparency are lowered, and the moldability is lowered. On the contrary, when the branching ratio of the aromatic polycarbonate resin is less than the lower limit described above, the melt tension may be lowered and the flame retardancy may be lowered.

The weight average molecular weight (Mw) of the aromatic polycarbonate resin is 2.0 x 10 ⁴ or more and 5.0 x 10 ⁴ or less. The upper limit of the weight average molecular weight (Mw) of the aromatic polycarbonate resin is more preferably 4.8 × 10 ⁴ , and further preferably 4.6 × 10 ⁴ . The lower limit of the weight average molecular weight (Mw) of the aromatic polycarbonate resin is more preferably 2.2 x 10 ^{4, and} still more preferably 2.4 x 10 ⁴ . When the weight average molecular weight (Mw) of the aromatic polycarbonate resin exceeds the upper limit, the moldability may be deteriorated. On the other hand, when the weight average molecular weight (Mw) of the aromatic polycarbonate resin is less than the lower limit described above, the mechanical strength may be lowered.

The ratio (Mw / Mn) of the weight average molecular weight to the number average molecular weight in terms of polystyrene of the aromatic polycarbonate resin measured by gel permeation chromatography is 1.0 or more and 2.5 or less. The upper limit of the ratio (Mw / Mn) of the weight average molecular weight to the number average molecular weight is more preferably 2.3, and still more preferably 2.1. The lower limit of the ratio (Mw / Mn) of the weight average molecular weight to the number average molecular weight is more preferably 1.3, and further preferably 1.5. When the ratio (Mw / Mn) of the weight average molecular weight to the number average molecular weight exceeds the upper limit, there is a fear that the light transmittance is lowered. On the other hand, when the ratio (Mw / Mn) of the weight average molecular weight to the number average molecular weight is less than the above lower limit, there is a fear that the moldability is lowered. The ratio (Mw / Mn) of the weight average molecular weight to the number average molecular weight can be measured using "PLGel 5μ MIXED-C" manufactured by Polymer Laboratories as a column and tetrahydrofuran as a solvent. The ratio (Mw / Mn) of the weight-average molecular weight to the number-average molecular weight can be adjusted by adjusting the material to be used for the molecular weight adjuster, the timing of addition or the like and adjusting the polymerization conditions such as reaction time and reaction temperature Do.

Not particularly limited. Examples of the aromatic polycarbonate melt volume flow rate (300 ℃, 1.2kg load) of the resin, a 15cm ³ / 10min at least 80cm ³ / 10min or less. The upper limit of the melt volume flow rate was 75cm ³ / 10min, and more preferably, 70cm ³ / 10min are more preferred. On the other hand, the lower limit of the melt volume flow rate was 17cm ³ / 10min, and more preferably, 20cm ³ / 10min are more preferred. When the melt volume flow rate exceeds the upper limit, the melting temperature is lowered, and the discharge amount in the case of melt-extrusion molding becomes unstable, which may lower moldability. On the contrary, when the melt volume flow rate is lower than the lower limit, the melting temperature becomes high, and when the melt-extrusion-molding is performed, the filter installed between the extruder and the die becomes easy to clog.

The light guide film 12 may contain a polystyrene type resin having a weight average molecular weight of 1000 to 10000. The weight average molecular weight of the polystyrene type resin is more preferably from 1,500 to 8,000, and still more preferably from 2,000 to 5,000. When the weight average molecular weight of the polystyrene type resin exceeds the upper limit, the light transmittance may be lowered.

The content of the polystyrene resin is not particularly limited, but is preferably 0.1 part by mass or more and 3 parts by mass or less based on 100 parts by mass of the aromatic polycarbonate resin. The upper limit of the content of the polystyrene-based resin with respect to 100 parts by mass of the aromatic polycarbonate-based resin is more preferably 2 parts by mass, further preferably 1 part by mass. The lower limit of the content of the polystyrene-based resin relative to 100 parts by mass of the aromatic polycarbonate-based resin is more preferably 0.2 parts by mass, further preferably 0.3 parts by mass. When the content of the polystyrene-based resin exceeds the upper limit, the light transmittance may be lowered. Conversely, when the content of the polystyrene-based resin is less than the lower limit, there is a possibility that the effect of improving the light transmittance may not be obtained.

The light guide film 12 may include a thermoplastic polyacrylic resin. The thermoplastic polyacrylic resin is not particularly limited and examples thereof include polyacrylic acid, polymethyl methacrylate (PMMA), polyacrylonitrile, acrylic acid-n-butyl-acrylonitrile copolymer, ethyl acrylate-2 -Chloroethyl copolymer, an acrylonitrile-butadiene copolymer, an acrylonitrile-butadiene-styrene copolymer, and the like. Among them, polymethyl methacrylate (PMMA) is particularly preferable.

The content of the thermoplastic polyacrylic resin is not particularly limited, but is preferably 0.01 part by mass or more and 1 part by mass or less based on 100 parts by mass of the aromatic polycarbonate resin. The upper limit of the content of the thermoplastic polyacrylic resin with respect to 100 parts by mass of the aromatic polycarbonate resin is more preferably 0.7 part by mass, further preferably 0.5 part by mass. The lower limit of the content of the thermoplastic polyacrylic resin with respect to 100 parts by mass of the aromatic polycarbonate resin is more preferably 0.03 parts by mass, further preferably 0.05 parts by mass. When the content of the thermoplastic polyacrylic resin exceeds the above upper limit, the effect of improving the transparency is not sufficiently obtained, and the spectral light transmittance may not be improved. Conversely, when the content of the thermoplastic polyacrylic resin is less than the above lower limit, the transparency may be lowered.

The molecular weight of the thermoplastic polyacrylic resin is not particularly limited, but is preferably 5,000 or more and 100,000 or less. The upper limit of the molecular weight of the thermoplastic polyacrylic resin is more preferably 80,000, and more preferably 60,000. The lower limit of the molecular weight of the thermoplastic polyacrylic resin is more preferably 10,000, and more preferably 20,000. When the molecular weight of the thermoplastic polyacrylic resin is in the above range, phase separation at the time of molding is suppressed, and the transparency is suitably improved.

The light guide film 12 contains an antioxidant. The antioxidant is not particularly limited, and examples thereof include hindered phenol compounds and thioether compounds. Among them, hindered phenol compounds are preferable as the antioxidants, pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate is particularly preferable.

The content of the antioxidant is 0.01 part by mass or more and 0.1 part by mass or less based on 100 parts by mass of the aromatic polycarbonate resin. The upper limit of the content of the antioxidant is preferably 0.08 part by mass, more preferably 0.07 part by mass, per 100 parts by mass of the aromatic polycarbonate resin. On the other hand, the lower limit of the content of the antioxidant is preferably 0.03 parts by mass, more preferably 0.04 parts by mass, per 100 parts by mass of the aromatic polycarbonate resin. When the content of the antioxidant exceeds the upper limit, there is a possibility that the effect of containing the antioxidant may not be improved. On the contrary, when the content of the antioxidant is less than the above lower limit, there is a possibility that the effect of containing an antioxidant may not be sufficiently obtained.

The light guide film 12 may contain optional components such as an ultraviolet absorber, a flame retardant, a stabilizer, a lubricant, a processing aid, a plasticizer, an impact resistance auxiliary, a retardation reducing agent, a gloss removing agent, an antimicrobial agent and an antifungal agent.

The spectral light transmittance of the light guide film 12 at a wavelength of 300 nm is not particularly limited, but is preferably 65% or more, more preferably 70%, further preferably 73%. Since the light guide film 12 has the above-mentioned spectral light transmittance in the above range, the light guide property can be enhanced and the luminance can be improved. Further, the light guide film 12 makes the light rays of the wavelength of the visible light region incident from the end face to propagate. At this point, the spectral light transmittance at a wavelength of 300 nm does not directly indicate the spectral light transmittance in the visible light region, but tends to reflect the spectral light transmittance in the visible light region.

The refractive index of the light guide film 12 is not particularly limited, but is preferably 1.56 to 1.68, more preferably 1.57 to 1.66.

The pencil hardness of the light guide film 12 is not particularly limited, but is preferably 3B or more, more preferably 2B or more. When the pencil hardness of the light guide film 12 is less than the above lower limit, scratch resistance is not sufficiently obtained, and the surface or the back surface is scratched, and there is a possibility that a luminance deviation occurs due to the light beam incident on this scar.

The diffusion pattern 14 is composed of a plurality of concave portions formed on the back surface of the light guide film 12. The plurality of concave portions are formed in a dot shape scattered on the back surface of the light guide film 12. [ The plurality of concave portions are arranged so as to emit uniform light from the light guide film 12 to the surface side. Concretely, the plurality of recesses are formed such that the existence ratio at the position near the light source 17 is small and the existence ratio increases as the distance from the light source 17 is increased. The adjustment of the existence ratio of the plurality of recesses can be performed by adjusting the arrangement position of the recesses while changing the size of each recesses or by changing the size of each recesses. However, in order to improve the light-guideability while promoting the thinning of the light guide film 12, it is preferable to adjust the arrangement position while keeping the sizes of the concave portions the same.

The average diameter of the concave portion is not particularly limited, but is preferably 50 占 퐉 or less. The upper limit of the average diameter of the concave portion is more preferably 40 占 퐉, and still more preferably 30 占 퐉. On the other hand, the lower limit of the average diameter of the concave portion is preferably 0.5 占 퐉, more preferably 1 占 퐉, and further preferably 5 占 퐉. When the average diameter of the concave portion exceeds the upper limit, there is a fear of causing a luminance deviation, and the height of the concave portion is increased, thereby making it difficult to promote thinning of the light guide film 12. Conversely, when the average diameter of the concave portion is less than the lower limit, there is a possibility that the light scattering effect may not be sufficiently obtained. The &quot; diameter &quot; means an intermediate value between the maximum width of the outer shape and the width of the outer shape orthogonal to the maximum width direction. The &quot; average diameter &quot; refers to an average value of diameters of a plurality of recesses.

The shape of the concave portion is not particularly limited, but may be hemispherical, conical, cylindrical, polygonal, polygonal, horseshoe, or the like. Among them, the concave portion is desirably formed as a hemispherical concave portion. By forming the concave portion into a hemispherical concave portion, the formability is improved, edges can be prevented from occurring, and thinning is promoted.

The surface of the light guide film 12 has a wave-like fine modulation structure 15. In addition, the ridgeline direction of the wave-like fine modulation structure 15 and the end surface on which the light beam is incident are positioned substantially parallel. As a result, the ridge line direction of the fine modulation structure 15 is substantially perpendicular to the traveling direction of the light beam propagating in the light guide film 12, The light output from the surface of the light guide film 12 is improved because of the fluctuation of the incident angle of the light to the light guide film 12.

The ridge line p in the fine modulation structure 15 is not particularly limited, but is preferably 1 mm or more and 500 mm or less. The upper limit of the ridge line interval p is more preferably 100 mm, and further preferably 60 mm. On the other hand, the lower limit of the ridge line interval p is more preferably 10 mm, and further preferably 20 mm. When the ridge line interval is less than the above lower limit, there is a possibility that light rays are excessively emitted from the surface of the light guide film 12 concerned. On the other hand, when the ridge line interval exceeds the upper limit, there is a possibility that the effect of improving the light emitting performance of the light guide film 12 is low. Although it is preferable that all the ridge line intervals in the fine modulation structure 15 are within the above range, some of the ridge line intervals p in the fine modulation structure 15 may be outside the above range. In this case, , The ridge line spacing of 50% or more, preferably 70%, of the plurality of ridge lines may be within the above range.

The average height h of the ridgelines based on the approximate imaginary plane through which a plurality of curves in the fine modulation structure 15 pass is not particularly limited, but is preferably 5 占 퐉 or more and 40 占 퐉 or less. The upper limit of the average height h is more preferably 20 占 퐉, and further preferably 15 占 퐉. On the other hand, the lower limit of the average height h is more preferably 7 占 퐉, and further preferably 9 占 퐉. When the average height h is less than the lower limit, there is a possibility that the effect of improving the light outputting property of the light guide film 12 is low. On the other hand, when the average height h exceeds the upper limit, light rays may be emitted from the surface of the light guide film 12 excessively.

(The reflective sheet 13)

The reflective sheet 13 reflects the light beam emitted from the back side of the light guide film 12 to the surface side. As the reflective sheet 13, a metal such as aluminum or silver is deposited on the surface of a film formed of a white sheet in which a filler is dispersedly contained in a base resin such as a polyester resin, or a polyester resin, Sheet and the like.

(Top plate 16)

The top plate 16 is formed of a plate made of metal or synthetic resin. As the metal top plate 16, for example, a plate made of aluminum can be used. Here, the thickness of the plate is preferably 500 탆 or more and 1200 탆 or less, more preferably 700 탆 or more and 900 탆 or less. Further, the top plate 16 is formed by curving the periphery of the plate material toward the front side, and the curved portion functions as a rib and has sufficient strength as the top plate 16. [ Further, the portion (central portion) other than the full width portion of the rib is a flat surface, but it is also possible to emboss a pattern such as a geometric shape.

(Light source 17)

The light source 17 is built in the casing 6 for the liquid crystal display part and is arranged so that the irradiation surface is opposed (or contacted) with the end surface of the light guide film 12. [ A variety of light sources 17 can be used, and for example, light emitting diodes (LEDs) can be used. Specifically, as the light source 17, a plurality of light emitting diodes arranged along the end surface of the light guide film 12 can be used.

In the backlight unit 11, a single-sided edge light system in which a light source 17 is arranged on one side of only one side edge of the light guide film 12, Side edge light system in which the light sources 17 are arranged in each of the light guide films 12 and an all-around edge light system in which the light sources 17 are arranged at the sides of each side edge of the light guide film 12.

<Manufacturing Method of Light Guide Film 12>

Next, a method of manufacturing the light guide film 12 will be described. The light guide film 12 is formed by an extrusion molding method.

The light guide film 12 has a step of forming a film having an average thickness of 600 μm or less (STEP 1) and a step of forming a diffusion pattern 14 on the back surface (STEP 2). STEP1 and STEP2 are performed simultaneously using the extrusion molding apparatus 21 of Fig.

The extrusion molding apparatus 21 has an extruder and a T die 22, a pair of press rolls 23, and a winding device (not shown). As the T die 22, well-known materials such as a fish tail die, a manifold die, a coat hanger die and the like can be used. The pair of press rolls 23 are arranged adjacent to each other in parallel. The extruder and the T die 22 are configured to push the molten resin into the nip of the pair of press rolls 23 in a sheet form. The pair of press rolls 23 are provided with a temperature control means so that the surface temperature can be controlled at a temperature optimum for extrusion molding. It is preferable to use a metal elastic roll comprising a metal roll as the pressing roll 23 and a flexible roll whose surface is covered with an elastic body.

The pair of press rolls 23 are composed of a press roll 23a and a press roll 23b. Among them, the pressing roll 23a is formed as an inverted type in which the diffusion pattern 14 is transferred to the surface.

In STEP 1, the material for forming the light guide film 12 in the melted state is supplied to the T die 22, the material is pushed out from the extruder and the T die 22, and then pressed by the pair of press rolls 23 Is carried out by a melt extrusion molding method. The melting temperature of the material for forming the light guide film 12 to be extruded from the T die 22 is suitably selected in consideration of the melting point of the resin to be used and the like. The average thickness of the light guide film 12 formed in STEP 1 is 600 占 퐉 or less. The average thickness of the light guide film 12 is adjusted by, for example, adjusting the intervals at which the pair of press rolls 23 are arranged. Further, in STEP 1, the fine modulation structure 15 having a wavy surface can be formed by making the cross-sectional shape of the T die 22 an inverted shape of the fine modulation structure 15.

Step 2 is performed by transferring the diffusion pattern 14 transferred to the surface of the pressing roll 23a before the material for forming the light guide film 12 in a molten state is cured. The diffusion pattern 14 transferred onto the surface of the pressing roll 23a is pressed against the surface of the light guide film 12 by the pair of pressing rolls 23, Is transferred to the back surface. In STEP 2, the diffusion pattern 14 is formed on the back surface of the light guide film 12 by this transfer. The average diameter of the concave portions formed in STEP 2 is not particularly limited, but is preferably 50 탆 or less. The average diameter of the concave portion is adjusted by adjusting the average diameter of the concave portion to be transferred to the surface of the press roll 23a.

STEP1 and STEP2 may be performed in-line as described above, but may be performed offline.

<Advantages>

The light guide film 12 has a weight average molecular weight of an aromatic polycarbonate resin and a ratio (Mw / Mn) of a weight average molecular weight to a number average molecular weight of the aromatic polycarbonate resin in terms of polystyrene measured by gel permeation chromatography ) Is in the above-mentioned range, it is possible to enhance both the light transmittance after molding and the mechanical strength while improving the extrusion moldability. Therefore, the light guide film 12 can have an average thickness within the above-mentioned range, and can also cope with a large-sized screen. Further, by containing the antioxidant in the above ratio in the light guide film 12, it is possible to prevent yellowing at the time of molding and to prevent reduction in luminance.

Since the light guide film 12 has a diffusion pattern on the back surface side, it is possible to improve the surface uniformity by adjusting the emission characteristics of the light beam emitted from the surface.

The diffusion pattern 14 of the light guide film 12 can be easily and surely formed by transferring the diffusion pattern 14 transferred to the surface of the pressing roll 23a before the material for forming the light guide film 12 is cured . Further, since the diffusion pattern 14 of the light guide film 12 is not provided on the back surface, the thickness of the light guide film 12 is not increased by forming the diffusion pattern 14. Therefore, the light guide film 12 can promote thinning.

Since the ultra-thin liquid crystal backlight unit 11 has the light guide film 12 with improved light transmittance and mechanical strength, the extrusion moldability is improved, and the thin liquid crystal backlight unit 11 can cope with a large screen while promoting thinness. The ultrathin liquid crystal backlight unit 11 according to the present invention has a reflecting sheet 13 arranged on the back surface of the light guide film 12 to prevent the back surface of the light guide film 12 from being damaged. Therefore, in the ultra-thin liquid crystal backlight unit 11, a light beam is incident on a scratch on the back surface of the light guide film 12, and the light ray is irregularly reflected, thereby preventing a luminance deviation from occurring.

Since the laptop computer 1 is provided with the ultra-thin liquid crystal backlight unit 11 in the liquid crystal display unit 3, thinning is promoted, brightness is prevented from being lowered, and it is possible to cope with a large screen.

[Second Embodiment]

&Lt; Backlight unit 31 >

The backlight unit 31 shown in Fig. 4 is replaced with the backlight unit 11 shown in Fig. 2 and is used as an edge light type ultra-thin liquid crystal backlight unit of a liquid crystal display part of a laptop computer having a housing thickness of 21 mm or less.

The backlight unit 31 has a light guide film 32, a top plate 33 on which the light guide film 32 is directly laminated and a light source 17 for irradiating the light guide film 32 with light. That is, the backlight unit 31 does not have a reflective sheet arranged between the top plate 33 and the light guide film 32 as in the conventional art. Since the light source 17 is the same as the backlight unit 11 of Fig. 2, the same reference numerals are given and the description is omitted.

(Light guide film 32)

The light guide film 32 emits the light ray incident from the end surface almost uniformly from the surface. The light guide film 32 is formed in a substantially quadrangular shape in plan view, and is formed in a substantially uniform plate shape (non-wedge shape). A diffusion pattern 34 is formed on the back surface of the light guide film 32. The average thickness, forming material, spectral light transmittance, refractive index and pencil hardness of the light guide film 32 are the same as those of the light guide film 12 of Fig.

The diffusion pattern 34 is formed by a plurality of light scattering parts developed by laser irradiation. Specifically, the diffusing pattern 34 is formed by containing a coloring agent in the material for forming the light guide film 32, and by irradiating the light guide film 32 with a laser after forming the coloring agent.

The coloring agent dispersed and contained in the forming material of the light guide film 32 is a pigment whose color is discolored by laser irradiation. As the coloring agent, a well-known organic material or inorganic material used as a laser marking agent can be used. Specific examples thereof include metal compounds such as yellow iron oxide, inorganic lead compounds, manganese violet, cobalt violet, mercury, cobalt, copper, bismuth and nickel; pearl luster pigments; silicon compounds; mica; kaolins; , Talc, and the like. Of these, one kind or two or more kinds can be used. However, in the present embodiment, since the diffusion pattern 34 is formed as a reflection pattern for reflecting light rays, it is preferable that the diffusion pattern 34 has a color that reflects light rays. Therefore, in the light guide film 32, it is preferable to use a coloring agent which develops white color by laser irradiation, and on the contrary, a coloring agent which is carbonized by laser irradiation and changes to black which absorbs light is inadequate. Examples of such a coloring agent that develops white color include titanium black, cordierite, mica, and the like.

As the cordierite, in addition to the inorganic compound represented by the composition formula MG ₂ Al ₃ (AlSi ₅ O ₁₈ ), one in which a part of Mg is substituted with Fe can be used. Further, a material containing water may be used.

As the mica, synthetic mica such as natural mica such as Muscobite, flurophite, biotite, and sericite, fumaric mica, fluorine tetra-silicate mica and the like can be used.

The content of the color developer is preferably from 0.0001 mass% to 2.5 mass%, more preferably from 0.1 mass% to 1 mass%. When the content of the coloring agent is less than the above lower limit, a sufficient coloring effect can not be obtained at the time of laser irradiation, and a desired reflection pattern can not be formed. On the other hand, when the content of the coloring agent exceeds the upper limit, the transparency and mechanical strength of the light guide film 32 may be lowered.

The laser for irradiating the light guide film 32 is not particularly limited, and examples thereof include a carbon dioxide gas laser, a carbon monoxide laser, a semiconductor laser, and a YAG (yttrium aluminum garnet) laser. Among them, a carbon dioxide gas laser having a wavelength of 9.3 占 퐉 to 10.6 占 퐉 is suitable for forming a fine dot pattern. As the carbon dioxide gas laser, a lateral atmospheric pressure excitation (TEA) type, a continuous oscillation type, a pulse oscillation type, or the like can be used.

The shape of the light scattering portion is not particularly limited, but may be hemispherical, conical, cylindrical, polygonal, polygonal, horseshoe, or the like. Among them, hemispherical shape is preferable as the shape of the light scattering portion. By forming the light scattering portion into a hemispherical shape, it is possible to improve the moldability and to prevent an edge from being generated. The arrangement pattern of the diffusion patterns 34 is the same as the diffusion pattern 14 of FIG. The average diameter of the light scattering portion is the same as that of the concave portion in Fig.

Further, the light guide film 32 is formed by the laser irradiation with the diffusion pattern 34. Therefore, for the production of the light guide film 32, the diffusion pattern 34 need not be transferred to the surface of the press roll.

(Top plate 33)

The top plate 33 is formed of a metal plate, specifically, an aluminum plate. The thickness of the top plate 33 is the same as that of the backlight unit 11 in Fig.

A reflecting surface 33a for reflecting light is formed on the surface of the top plate 33 (the surface on the liquid crystal panel 4 side). Therefore, the light emitted from the back surface of the light guide film 32 is reflected to the surface side by the reflection surface 33a.

The reflecting surface 33a is formed by polishing the surface of the top plate 33. However, the forming method is not particularly limited, and a method other than polishing may be used.

The arithmetic mean roughness (Ra) of the reflecting surface 33a (the surface of the plate material of the top plate 33) is not particularly limited, but is preferably 0.2 탆 or less, more preferably 0.1 탆 or less, desirable. When the arithmetic average roughness Ra of the reflecting surface 33a exceeds the upper limit, the light incident on the reflecting surface 33a is difficult to be regularly refracted, and the light utilization efficiency may be lowered. In addition, 32 may be easily scratched. In addition, the arithmetic average roughness Ra of the reflecting surface 33a can be easily and surely adjusted by polishing the surface of the top plate 33. [

<Advantages>

Since the light guide film 32 is made up of a plurality of light scattering parts in which the diffusion pattern 34 is colored by laser irradiation, a desired diffusion pattern 34 can be easily and reliably formed. Further, in the case of forming the diffusion pattern 34 by such a method, it is not necessary to provide a convex portion or the like on the back surface of the light guide film 32, so that the thinning can be promoted.

Since the ultra-thin liquid crystal backlight unit 31 has the light guide film 32 improved in extrusion moldability and improved light transmittance and mechanical strength, the ultra thin liquid crystal backlight unit 31 can cope with a large screen while promoting thinness. In addition, since the ultra-thin liquid crystal backlight unit 31 does not use a conventional reflective sheet, thinning is further promoted.

[Other Embodiments]

In addition, the light guide film ultra-thin liquid crystal backlight unit and portable computer of the present invention can be carried out in a mode in which various modifications and improvements are made in addition to the above. For example, the configurations in the above-described embodiments can be appropriately combined. The diffusion pattern can be formed by various methods such as a printing method such as inkjet printing or screen printing, or a hot pressing method using a plate-like inverted type. A hard coat layer or other layers may be laminated on the front surface or back surface of the light guide film.

The light guide film does not necessarily have a fine modulation structure. When the light guide film has a fine modulation structure, the ridge line direction in the fine modulation structure and the end face on which the light ray is incident may be almost orthogonal. As a result, when the light beam propagating in the light guide film is reflected on the surface, the traveling direction of a part of the light beams approaches the ridge line side, so that the light ray is easily condensed toward the ridge line side. In addition, in addition to this, the diffusibility of the outgoing light is improved because the light emitted from the surface is slightly diffused in the direction perpendicular to the ridgeline by the refraction in the fine modulation structure of the wave.

The ridge line interval in the fine modulation structure is not particularly limited, but is preferably 1 mm or more and 500 mm or less. The upper limit of the ridge line interval is more preferably 100 mm, and further preferably 60 mm. On the other hand, the lower limit of the ridge line interval is more preferably 10 mm, and further preferably 20 mm. When the ridge line interval is out of the above range, light rays propagating in the light guide film are difficult to be condensed toward the ridge line side. It is preferable that all of the ridge line distances in the fine modulation structure are within the above range. However, some of the ridge line intervals in the fine modulation structure may be outside the above range. In this case, Preferably, the ridge line spacing of 70% is within the above range.

The average height of the ridgelines based on the approximate imaginary plane through which a plurality of curves in the fine modulation structure pass is not particularly limited, but is preferably 5 占 퐉 or more and 40 占 퐉 or less. The upper limit of the average height is more preferably 20 占 퐉, and further preferably 15 占 퐉. On the other hand, the lower limit of the average height is more preferably 7 탆, and further preferably 9 탆. When the average height is out of the above range, light rays propagating in the light guide film are difficult to be condensed toward the ridgeline side.

Although the first embodiment has been described in the case where the step of forming a film having an average thickness of 600 μm or less (STEP 1) and the step of forming a diffusion pattern (STEP 2) are performed in-line, May be performed offline. As such a method for performing STEP1 and STEP2 off-line, for example, there is a method in which the film produced in STEP1 is wound in a roll shape, and then the film is taken out from the roll-shaped state and STEP2 is performed .

The portable computer may be an ultra-thin laptop computer, or a portable computer terminal such as a smart phone or a portable information terminal such as a tablet terminal.

As described above, the light guide film and the ultra-thin liquid crystal backlight unit of the present invention can promote thinning of the portable computer and prevent the luminance from being lowered. Therefore, for example, it is possible to use an ultra- And portable information terminals such as portable terminals and tablet terminals.

1 laptop computer, ultra-thin computer
2 Control unit
3 liquid crystal display
4 liquid crystal panel
6 Casing for liquid crystal display part
7 surface supporting member
8 Hinge section
9 Casing for the operating unit
11 Ultra thin liquid crystal backlight unit, backlight unit
12 light guide film
13 reflective sheet
14 diffusion pattern
15 Fine modulation structure
16 top plate
17 light source
21 Extrusion molding device
22 T die
23 Press Roll
31 Backlight unit (ultra-thin liquid crystal backlight unit)
32 light guide film
33 Top plate
33a Reflective surface
34 diffusion pattern
110 Edge Light Type Backlight Unit
111 Light guide plate
115 reflective sheet
116 Top plate
117 light source
210 Edge light type backlight unit
211 Light guide plate
216 Top plate
216a reflecting surface
217 Light source

Claims (12)

A light guide film for an ultra-thin liquid crystal backlight unit having an average thickness of 600 占 퐉 or less which emits a light beam incident from an end face substantially uniformly from a surface,
An aromatic polycarbonate resin as a main component and an antioxidant in an amount of 0.01 part by mass or more and 0.1 part by mass or less based on 100 parts by mass of the aromatic polycarbonate resin,
Wherein the aromatic polycarbonate resin has a weight average molecular weight of from 2.0 x 10 ⁴ to 5.0 x 10 ⁴ ,
The ratio (Mw / Mn) of the weight average molecular weight to the number average molecular weight in terms of polystyrene of the aromatic polycarbonate resin measured by gel permeation chromatography is 1.0 or more and 2.5 or less,
A light guide film characterized by being molded by an extrusion molding method. The method of claim 1, wherein the aromatic polycarbonate melt volume flow rate (300 ℃, 1.2kg load) of the resin is 15cm ³ / 10min at least 80cm ³ / 10min light guide film, characterized in that not more than. The light guide film according to claim 1, wherein the aromatic polycarbonate resin has a branching ratio of 0.5 mol% or more and 1.5 mol% or less. The light guide according to claim 1, comprising a polystyrene type resin having a weight average molecular weight of 1,000 to 10,000, and being contained in an amount of not less than 0.1 parts by mass and not more than 3 parts by mass based on 100 parts by mass of the aromatic polycarbonate resin film. The light guide film according to claim 1, wherein the spectral light transmittance at a wavelength of 300 nm is 65% or more. The light guide film according to claim 1, wherein the thermoplastic polyacrylic resin is contained in an amount of 0.01 part by mass or more and 1 part by mass or less based on 100 parts by mass of the aromatic polycarbonate resin. The light guide film according to claim 1, wherein the light guide film has a diffusion pattern on the back side. The light guide film according to claim 7, wherein the diffusion pattern comprises a plurality of light scattering parts developed by laser irradiation. A top plate whose surface is formed as a reflective surface and which is located at the backmost surface of the liquid crystal display section,
The light guide film according to claim 1, which is laminated on the surface of the top plate
A light source for irradiating light to the end surface of the light guide film
And a liquid crystal panel. The ultra-thin liquid crystal backlight unit according to claim 9, wherein the top plate is made of metal, and the arithmetic mean roughness (Ra) of the reflecting surface is 0.2 탆 or less. A top plate positioned on the most rear surface of the liquid crystal display unit,
A reflective sheet laminated on the surface of the top plate,
The light guide film according to claim 1, which is laminated on the surface of the reflective sheet and
A light source for irradiating light to the end surface of the light guide film
And a liquid crystal panel. 11. A portable computer having the liquid crystal display unit with the ultra-thin liquid crystal backlight unit according to any one of claims 9 to 11.

Images