Embodiment
< light guiding plate is used resin combination >
Light guiding plate of the present invention contains transparent resin and Titanium Dioxide (Rutile) Top grade particulate with resin combination (following only be designated as sometimes " resin combination ").
Light guiding plate of the present invention is with the transparent resin that contains in the resin combination, so long as transparent, then do not limit composition, weight-average molecular weight etc. especially.For example, can enumerate metha crylic resin (polymethylmethacrylate (PMMA) etc.), polycarbonate resin, acrylonitrile-styrene-butadiene copolymer resin (ABS resin), polystyrene resin, acrylonitritrile-styrene resin resin (AS resin), polyolefin resin (Vilaterm, Vestolen PP 7052 etc.) etc.Wherein, be preferably the metha crylic resin.
The Titanium Dioxide (Rutile) Top grade particulate that contains in the resin combination of the present invention is used to spread the light through light guiding plate.
According to crystalline texture, titanium oxide has kinds such as rutile-type, anatase titanium dioxide, and what use in the present invention is the Titanium Dioxide (Rutile) Top grade particulate.For diffusion light more effectively, the Titanium Dioxide (Rutile) Top grade particulate preferably has the median size of 0.1~4 μ m, more preferably has the median size of 0.2~0.8 μ m.
With respect to the gross weight of resin combination, preferably with 0.01~5ppm, more preferably with 0.1~3ppm, further preferably the ratio with 0.1~1ppm contains the Titanium Dioxide (Rutile) Top grade particulate.
When resin combination of the present invention is processed formed body; Average light transmittance in the wavelength region may of the 300nm~800nm that in the optical length of 200mm, records is preferably 15~85%; More preferably 25~70%; Thus, in the time of the yellow chromaticity of the light guiding plate that can suppress to obtain, realize high brightnessization.
< light guiding plate >
Light guiding plate of the present invention is made up of above-mentioned resin combination.Particularly, light guiding plate of the present invention is with above-mentioned resin combination, for example utilize extrusion moulding, injection molding method, hot extrusion molding method to wait moulding and.
In aforementioned light guiding plate, for example can add the various additives of UV light absorber, thermo-stabilizer, inhibitor, weather resisting agent, photostabilizer, white dyes, processing stabilizers etc.
Thickness to light guiding plate does not have special qualification, is generally 0.05~15mm, is preferably 0.1~10mm, more preferably 0.5~5mm.
< planar light source device and liquid crystal indicator >
Next, represent to use the planar light source device of the light guiding plate that constitutes by resin combination of the present invention and a kind of embodiment of the liquid crystal indicator that uses this planar light source device with Fig. 1.
This liquid crystal indicator 1 possesses planar light source device 9 and liquid crystal display 30, and planar light source device 9 is disposed at the rear side of liquid crystal display 30.
Liquid crystal display 30 possesses liquid crystal cells 20 and is disposed at the polaroid 14,15 of the both sides up and down of liquid crystal cells 20; Wherein, said liquid crystal cells 20 is at a pair of up and down transparency electrode 12 that is configured with parallel shape, the liquid crystal cells of enclosing liquid crystal 11 between 13 with being separated from each other.By these liquid crystal 11, transparency electrode 12,13 and polaroid 14,15 composing images display parts.Should explain alignment films (not shown) arranged in that the inner face (face of liquid crystal side) of transparency electrode 12,13 is range upon range of respectively.
Planar light source device 9 is disposed at the lower face side (rear side) of above-mentioned polaroid 15.This planar light source device 9 possesses: overlook rectangular shape and upper surface side (front surface side) by the lamp box 5 of the thin box shape opened; Be accommodated in light guiding plate 3 and light source 2 in the lamp box 5, and the light diffusing sheet 4 that is configured and is fixed with the mode of the open surface of blocking lamp box 5.Light source 2 for example is LED (photodiode) light source etc., and it is configured in the position, side of light guiding plate 3.
Lamp box 5 is made up of white acrylic resin plate.Constitute as follows: 3a is formed with the round dot Printing Department (round dot pattern) that is formed by white ink at the back side of light guiding plate 3; The light that in light guiding plate 3, inject from light source 2 from the one of which side; Utilize round dot Printing Department to reflect, thereby light is penetrated from the front surface (being light emergence face 3b) of light guiding plate 3 equably.
Should explain that the light guiding plate 3 of use for example can as shown in Figure 2ly carry out milled processed to side face side 51, also can implement the light DIFFUSION TREATMENT in order on light emergence face 3b, to form uniform light.In addition, the light DIFFUSION TREATMENT that can implement to form prism etc. to the back side 3a of light guiding plate 3 to be to replace using the round dot printing of white ink etc., perhaps can carry out the reflection layer of the sheet, film etc. of silver-colored vapor deposition in the face setting beyond the light emergence face 3b of light guiding plate.
Can make liquid crystal indicator 1 of the present invention with the high brightness light that 30 ejaculations do not have the high whiteness of yellow hue in fact from planar light source device 9 towards liquid crystal display through such formation, therefore, can reproduce the color of liquid crystal display 30 exactly.Thereby, can realize that the nature and the high-grade bright colour that do not have yellow hue show.
In liquid crystal indicator shown in Figure 11, be employed in the formation of a side configuration light source 2 in 4 sides of light guiding plate 3, but be not particularly limited to this formation.For example, can be employed in the formation that relative a pair of side in the light guiding plate 3 disposes light source 2 respectively.
Should explain, do not have special qualification, for example can enumerate the linear light source of cold-cathode tube, thermionic-cathode tube, external electrode fluorescent lamp (EEFL) etc., the point source of light of photodiode (LED) etc. etc. as light source 2.
According to the present invention, can provide a kind of light guiding plate to use resin combination, it is suitable for making, and yellow chromaticity is fully suppressed and light penetrates the excellent light guiding plate of efficient.Thereby the present invention is useful in the field of liquid crystal indicator etc.Light guiding plate of the present invention is specially adapted to the liquid-crystal display that possesses led light source of the so big picture of TV.
[embodiment]
Below, the present invention will be described particularly to enumerate embodiment and comparative example, but the present invention is not limited to these embodiment.
(embodiment 1)
(preparation of tabular sample (light guiding plate))
With the ratio of 0.1ppm Titanium Dioxide (Rutile) Top grade particulate (Sakai chemical industry (strain) system " R-42 ", specific refractory power are 2.6, median size be 0.3 μ m) is blended among the PMMA (Sumitomo Chemical (strain) system " SUMIPEX EXN ", specific refractory power are 1.49).Then; Use single shaft forcing machine (screw diameter 20mm) to carry out that fusion is mixed so that resin temperature reaches 250 ℃, extrude to be the twisted wire shape, carry out water-cooled; Utilize strand cutter cutting, obtain granular methylacrylic acid based resin composition (light guiding plate is used resin combination).
With the granular resin combination 160g heating compressed moulding that obtains, preparation has the square tabular sample of 210mm (light guiding plate) of the thickness of 3mm.
(embodiment 2)
With the mixed Titanium Dioxide (Rutile) Top grade particulate " R-42 " of 1ppm, in addition, carry out 1 identical operations with embodiment, obtain the methylacrylic acid based resin composition, prepare tabular sample.
(comparative example 1,2)
Replace Titanium Dioxide (Rutile) Top grade particulate " R-42 "; With the described mixed anatase type titanium oxide of table 1 particulate (Sakai chemical industry (strain) system " A-110 ", specific refractory power are 2.6, median size be 0.2 μ m); In addition; Carry out 1 identical operations, obtain the methylacrylic acid based resin composition, prepare tabular sample with embodiment.
(comparative example 3,4)
Replace Titanium Dioxide (Rutile) Top grade particulate " R-42 "; With the described mixed ps particle of table 1 (ponding changes into that article industry (strain) system " SBX-12 ", specific refractory power are 1.59, median size be 12 μ m); In addition; Carry out 1 identical operations, obtain the methylacrylic acid based resin composition, prepare tabular sample with embodiment.
Use the tabular sample that obtains in each embodiment and the comparative example, average the evaluation of light transmittance, yellowness index (YI) and total light flux.Evaluation method is as follows.
< mensuration of the average light transmittance of the visible light in the optical length of 200mm >
As shown in Figure 2, the tabular sample that obtains is cut into the size of wide 50mm * long 200mm.Then, 4 sides 51 are ground, obtain test film 50 with shredder (MEGAROTECHNICA CO., LTD system " PLA-BEAUTY PB-500 ").
Utilize the plastic properties of (strain) Hitachi system to measure system's (constituting) by U-4000 type spectrophotometer and large-scale sample chamber integrating sphere auxiliary equipment; In the scope of wavelength 300nm~800nm, the light transmittance in the optical length of the 200mm of this test film 50 is measured with every 5nm, with the arithmetical av of the light transmittance that obtains as " the average light transmittance of visible light ".The result is as shown in table 1.
< evaluation of yellowness index (YI) >
With the light transmittance of above-mentioned test film 50 in the optical length of 200mm; Utilizing above-mentioned plastic properties to measure system measures with every 5nm in the scope of wavelength 300nm~800nm; From the measured value that obtains; Obtain the XYZ value according to the described method of JIS Z-8722, calculate yellow chromaticity (YI) according to the described method of JIS K-7105.When YI less than 10, it is evaluated as yellow chromaticity is suppressed.The result is as shown in table 1.
< mensuration of total light flux >
As shown in Figure 3, the tabular sample that obtains is cut into the size of wide 60mm * long 80mm.Then, utilize shredder (MEGAROTECHNICA CO., LTD system " PLA-BEAUTY PB-500 ") that 4 sides 611,612,613,614 are ground, obtain test film 60.
Only the mode of injecting light of 1 side 611 from 4 sides of this test film 60 is shone the LED62 of 6 lamps, and remaining side 612,613,614 is sticked on that the inboard has the black bonding plane and has the adhesive tape ((strain) ridge, temple makes made reflection shading with film single face adhesive tape 6370) of white face in the outside.Through such Continuous pressing device for stereo-pattern, can measure the amount of the light of 611 irradiations from the side to the luminous light of the face direction on the two sides of test film 60.
Then; Test film 60 is installed in the sphere photometer (model 1500 types, diameter 1500mm) of (strain) NEM TECH (ネ system テ Star Network) system; Utilize the SLMS software of the Diode Array Spectrometer (MODEL DAS-1100/2100) of Labsphere corporate system, measure the optical throughput of the wavelength region may of 350~800nm.The result is as shown in table 1.
[table 1]
As shown in table 1, can know the embodiment 1 of use resin combination of the present invention and the tabular sample (light guiding plate) of embodiment 2, yellow chromaticity is by fully inhibition and light ejaculation efficient is excellent.On the other hand, comparative example 1,2 and 4 tabular sample (light guiding plate).Yellow chromaticity is not suppressed.In addition, the light of the tabular sample (light guiding plate) of comparative example 3 ejaculation efficient is low.