CN102455447A - Light diffusion plate and its manufacturing method, surface light source device and liquid crystal display device - Google Patents

Abstract

The invention provides a light diffusion plate and its manufacturing method, a surface light source device and a liquid crystal display device. The light diffusion plate (50) is arranged on the back surface of the liquid crystal panel (10) of a liquid crystal display device (1). A plurality of optical elements (53) extending along a first direction and arranged in parallel to each other at an interval P1 in a second direction orthogonal to the first direction are arranged on the surface of the liquid crystal panel. The spacing of the pixels (11) of the liquid crystal panel in the second direction is Pp and the spacing of the interference fringes of the periodic structure of the optical elements and the pixels in the second direction is Pm1and Pm2 respectively. When Pm1 = Pp*P1 / Pp-P1 and Pm2= 0.5Pp*P1/0.5Pp-P1, both Pm1and Pm2 are less than 1500 mu m through P1.

Description

Light diffusing sheet and manufacturing approach thereof and planar light source device and liquid crystal indicator

Technical field

The present invention relates to the manufacturing approach of light diffusing sheet, light diffusing sheet, the liquid crystal indicator that possesses the planar light source device of light diffusing sheet and possess light diffusing sheet.

Background technology

In the back light unit of infiltration type displays (permeation type visual display unit) such as LCD, use pointolites such as line source, LED such as CCFL.Back light unit converts thereof into planar light through making the light from line source or pointolite in the light diffusing sheet diffusion.In the past, use was the light diffusing sheet of mode that utilizes the light scattering of diffusant particle.Yet, in recent years,, bring into use optical element portion figurations such as lens and prisms in the light diffusing sheet on surface in order to satisfy requirement based on the cost degradation, low consumption electrification and the slimming that reduce lamp quantity.Because a plurality of optical element portion is configured to mutual almost parallel side by side on such figuration diffuser plate, so the figuration diffuser plate has periodic structure.On the other hand, because liquid crystal panel is that a plurality of pixels are arranged with constant interval, therefore also has periodic structure.If the liquid crystal panel with periodic structure is used the figuration diffuser plate with periodic structure simultaneously, then there is the situation that produces interference stripes in the relation of width (spacing) because of both.If produce the interference stripes in several millimeters cycles, then these interference stripes are easy to by human eye.Therefore the remarkable problem that descends of display level that has display.

As the technology that prevents such interference stripes, the for example known technology that has patent documentation 1 (TOHKEMY 2007-11292 communique) to be put down in writing.The technology that patent documentation 1 is put down in writing is used light diffusing sheet and diffusion film simultaneously; And based on the mist degree (haze) of pel spacing, diffusion film and total light transmittance and the optical element portion optimization that will on light diffusing sheet, form seeks to suppress the generation of interference stripes with this.

Yet, for example in the technology that patent documentation 1 is put down in writing, exist the formula ground of not following regularization in the patent documentation 1 to produce the situation of interference stripes.

Summary of the invention

Therefore, the object of the present invention is to provide the light diffusing sheet that can suppress interference stripes more reliably, the manufacturing approach of light diffusing sheet, the liquid crystal indicator that possesses the planar light source device of light diffusing sheet and possess light diffusing sheet.

Light diffusing sheet involved in the present invention is arranged at the plane of incidence side of liquid crystal panel, possess first of the liquid crystal panel side with first opposed second at least one square a plurality of optical element portion that becomes.Each optical element portion extends along first direction, a plurality of optical element portion with roughly configuration side by side on the second direction of quadrature of first direction.And then making the spacing on the said second direction of a plurality of optical element portion is P ₁[μ m], making the pel spacing on the second direction of a plurality of pixels that liquid crystal panel has is P _p[μ m] (but, P _p≠ P ₁And 0.5P _p≠ P ₁), making the interference stripes spacing based on the interference stripes of the periodic structure of a plurality of optical element portions on second direction is P _m1 [μ m], making the interference stripes spacing based on the interference stripes of the periodic structure of a plurality of pixels on second direction is P _m2 [μ m] are when utilizing formula (1) and formula (2) expression P respectively _m1 and P _m2 o'clock, above-mentioned P ₁For making P _m1 satisfies P _m1＜1500 μ m and P _m2 satisfy P _mThe value of 2＜1500 μ m.

${\mathrm{<figure-callout\; id="1"\; label="P\; m"\; filenames="HSA00000609744800011.png,HSA00000609744800021.png"\; state="\{\{state\}\}">P</figure-callout>}}_{m}1=\frac{P_p\&CenterDot;P_l}{|P_p-P_l|}\&CenterDot;\&CenterDot;\&CenterDot;\left(1\right)$

${\mathrm{<figure-callout\; id="2"\; label="P\; m"\; filenames="HSA00000609744800111.png"\; state="\{\{state\}\}">P</figure-callout>}}_{m}2=\frac{0.5P_p\&CenterDot;P_l}{|0.5P_p-P_l|}\&CenterDot;\&CenterDot;\&CenterDot;\left(2\right)$

With respect to comprising that the spacing on the second direction is configured to P _pThe liquid crystal panel of pixel use under the situation of above-mentioned light diffusing sheet above-mentioned P _m1 less than, 1500 μ m.Therefore, because of spacing P _pPeriodic structure and spacing P ₁Periodic structure and the interference stripes that produce are difficult for being looked recognizing.The present inventor finds: except because of the spacing P with the pixel that liquid crystal panel was had _pFor the periodic structure in cycle with the spacing P of optical element portion ₁Beyond the interference stripes that produce for the periodic structure in cycle, also produce spacing P sometimes with pixel _p1/2 be the interference stripes in cycle.Utilize formula (2) to represent the spacing of these interference stripes.And then, in light diffusing sheet involved in the present invention, because P ₁For making P _mThe 2 also values of less than 1500 μ m are therefore with spacing P _p1/2 also be difficult for looking recognizing for the interference stripes in cycle.Therefore, through using above-mentioned light diffusing sheet, make interference stripes be difficult for being looked recognizing more reliably.

In light diffusing sheet involved in the present invention, can be with above-mentioned P ₁Set for and make P _m1 satisfies P _m1≤1000 μ m and P _m2 satisfy P _mThe value of 2≤1000 μ m.In this case, interference stripes are difficult for being looked recognizing more.

In light diffusing sheet involved in the present invention, can be set at above-mentioned P _pBe below the above 535 μ m of 440 μ m, and above-mentioned P ₁Be below the above 335 μ m of 325 μ m.In this case, the P of any value below the 335 μ m more than with 325 μ m ₁Form a light diffusing sheet of optical element portion, with P _pWhen being liquid crystal panel 10 combinations below the above 535 μ m of 440 μ m, any liquid crystal panel combination with in this scope all can reduce looking of interference stripes and recognize.

In light diffusing sheet involved in the present invention, the width of the liquid crystal panel on making second direction is L [μ m], when making the quantity of the pixel on the second direction be N (N is the integer more than 1), can utilize L/N to represent P _pAnd an example of the above-mentioned optical element portion of light diffusing sheet involved in the present invention is a protuberance.

Planar light source device involved in the present invention is supplied with light to liquid crystal panel, possesses: output is towards the light source portion of the illumination light of liquid crystal panel; And be arranged at the light diffusing sheet involved in the present invention between light source portion and the liquid crystal panel.

In this planar light source device, from the light of light source portion output through behind the light diffusing sheet and export to the liquid crystal panel side.Owing to be formed with a plurality of optical element portion on the surface of the liquid crystal panel side of light diffusing sheet, therefore when light diffusing sheet penetrates, be easy to various directions ejaculations.Thus, the light from light source portion shines to liquid crystal panel as planar light.Because the light diffusing sheet that planar light source device had is the related light diffusing sheet of the invention described above, therefore under situation, is difficult for more reliably looking and recognizes interference stripes light diffusing sheet and the combination of above-mentioned liquid crystal panel.

Liquid crystal indicator involved in the present invention possesses: liquid crystal panel; Output is towards the light source portion of the illumination light of liquid crystal panel; And be arranged at the light diffusing sheet involved in the present invention between light source portion and the liquid crystal panel.

In this liquid crystal indicator, from the light of light source portion output through behind the light diffusing sheet and exported to the liquid crystal panel side.Owing to be formed with a plurality of optical element portion on the surface of the liquid crystal panel side of light diffusing sheet, therefore when light diffusing sheet penetrates, be easy to various directions ejaculations.Thus, the light from light source portion shines to liquid crystal panel as planar light.Because the light diffusing sheet that liquid crystal indicator had is the related light diffusing sheet of the invention described above, therefore is difficult for more reliably looking and recognizes interference stripes.

Above-mentioned liquid crystal indicator involved in the present invention can also possess the optically thin membranous part that comprises an optical thin film at least between liquid crystal panel and light diffusing sheet.The haze value H (%) of this optically thin membranous part satisfies 95≤H≤99.9.

In this case, be arranged between liquid crystal panel and the light diffusing sheet, so interference stripes are difficult for being looked recognizing more because haze value H satisfies the optical thin film of above-mentioned condition.

The manufacturing approach of light diffusing sheet involved in the present invention is for making the method for following light diffusing sheet: this light diffusing sheet is arranged at the plane of incidence side of liquid crystal panel; And have with the second direction of first direction quadrature on dispose a plurality of surfaces side by side along the optical element portion that first direction extends, the manufacturing approach of said light diffusing sheet possesses: to a plurality of optical element spacing Ps of portion on second direction ₁The operation that [μ m] designs; And based on the above-mentioned P that is designed ₁, form a plurality of optical element portions on one of the tabular body surface that has permeability and become light diffusing sheet and make the operation of light diffusing sheet.And then, at the above-mentioned spacing P of design ₁In the operation of [μ m], under the situation to liquid crystal panel configuration light diffusing sheet in liquid crystal indicator, the pel spacing of a plurality of pixels on second direction that liquid crystal panel is had is P _p[μ m] (but, P _p≠ P ₁And 0.5P _p≠ P ₁), making the interference stripes spacing based on the interference stripes of the periodic structure of a plurality of optical element portions on second direction is P _m1 [μ m], making the interference stripes spacing based on the interference stripes of the periodic structure of a plurality of pixels on second direction is P _m2 [μ m] are when utilizing formula (3) and formula (4) expression P respectively _m1 and P _m2 o'clock, with above-mentioned P ₁Decision is for making P _m1 satisfies P _m1＜1500 μ m and P _m2 satisfy P _mThe value of 2＜1500 μ m.

${\mathrm{<figure-callout\; id="1"\; label="P\; m"\; filenames="HSA00000609744800011.png,HSA00000609744800021.png"\; state="\{\{state\}\}">P</figure-callout>}}_{m}1=\frac{P_p\&CenterDot;P_l}{|P_p-P_l|}\&CenterDot;\&CenterDot;\&CenterDot;\left(3\right)$

${\mathrm{<figure-callout\; id="2"\; label="P\; m"\; filenames="HSA00000609744800111.png"\; state="\{\{state\}\}">P</figure-callout>}}_{m}2=\frac{0.5P_p\&CenterDot;P_l}{|0.5P_p-P_l|}\&CenterDot;\&CenterDot;\&CenterDot;\left(4\right)$

In above-mentioned manufacturing approach, with respect to the pel spacing P of employed liquid crystal panel _p, utilize formula (3) and formula (4) to come design pitch P ₁And then, make light diffusing sheet based on this design load.Therefore, to comprising that the spacing on the second direction is configured to P _pThe liquid crystal panel of pixel use under the situation of light diffusing sheet of manufacturing above-mentioned P _m1 less than, 1500 μ m.Therefore, because of spacing P _pPeriodic structure and spacing P ₁Periodic structure and the interference stripes that produce are difficult for being looked recognizing.In the light diffusing sheet that utilizes above-mentioned manufacturing approach to make, because P ₁For making P _mThe 2 also values of less than 1500 μ m are therefore with spacing P _p1/2 also be difficult for being looked recognizing for the interference stripes in cycle.Therefore, according to said method, even can produce the light diffusing sheet that also is difficult for seeing interference stripes with the liquid crystal panel combination more reliably.

To the above-mentioned spacing P of the design in the manufacturing approach of light diffusing sheet involved in the present invention ₁In the operation of [μ m], can be with P ₁Determine to become to make P _m1 satisfies P _m1≤1000 μ m and P _m2 satisfy P _mThe value of 2≤1000 μ m.In this case, when the light diffusing sheet and the liquid crystal panel set of manufacturing is fashionable, interference stripes become and are difficult for being looked more recognizing.

In the manufacturing approach of light diffusing sheet involved in the present invention, can be set at above-mentioned P _pBe below the above 535 μ m of 440 μ m and above-mentioned P ₁Be below the above 335 μ m of 325 μ m.In this case, the P of any value below the 335 μ m more than with 325 μ m ₁Be formed with a light diffusing sheet of optical element portion, with P _pBe that liquid crystal panel set below the above 535 μ m of 440 μ m is fashionable, no matter this light diffusing sheet makes up with any liquid crystal panel, all can reduce looking of interference stripes and recognize.Its result can reduce the production cost of the for example liquid crystal indicator etc. of the light diffusing sheet that possesses manufacturing.

In the manufacturing approach of light diffusing sheet involved in the present invention, the width of the liquid crystal panel on making second direction is L [μ m], when making the quantity of the pixel on the second direction be N (N is the integer more than 1), P _pRepresent by L/N.

The operation of the above-mentioned light diffusing sheet of manufacturing that manufacturing approach possessed of light diffusing sheet involved in the present invention can have: make the operation as the resin sheet of above-mentioned tabular body through extrusion modling; To a surface of resin sheet, push the spacing P that has as transfer mold with to be designed ₁The roller of the mould that a plurality of optical element portion of configuration is opposite, thus its transfer mold is needed on the operation on a surface; And the regulation zone that is formed with the resin sheet of a plurality of optical element portion through transfer printing is had transfer mold on a surface cuts out the operation that forms light diffusing sheet.

In the method, after forming resin sheet, have and spacing P to be designed through a pressed to resin sheet ₁The roller of the corresponding transfer mold of a plurality of optical element portions of arranging, thus a plurality of optical element portion formed on a surface of resin sheet.And then, cut out through the regulation zone as the resin sheet of tabular body that will be formed with a plurality of optical element portion and to obtain light diffusing sheet.

Description of drawings

Fig. 1 is the stereographic map of structure of an embodiment of schematically illustrated liquid crystal indicator involved in the present invention.

Fig. 2 is the synoptic diagram of cross-section structure at the II-II line place of liquid crystal indicator shown in Figure 1.

Fig. 3 is the stereographic map of structure of an embodiment of schematically illustrated light diffusing sheet involved in the present invention.

Fig. 4 is the cut-open view along the IV-IV line of Fig. 3.

Fig. 5 (a) figure is the synoptic diagram of liquid crystal indicator shown in Figure 1.Fig. 5 (b) figure is the synoptic diagram of the periodic structure of the interference stripes that produce of the periodic structure because of light diffusing sheet and liquid crystal panel.(c) figure of Fig. 5 is the synoptic diagram of the transmittance curve of liquid crystal panel.(d) figure of Fig. 5 is the synoptic diagram of the transmittance curve of light diffusing sheet.

The figure of one example of the pixel image when Fig. 6 is the FHD liquid crystal panel that illustrates with 32 inches of VA mode activated.

(a) figure of Fig. 7 is to illustrate having spacing P ₁The spacing and the spacing P of the fashionable interference stripes that produce of FHD liquid crystal panel set of periodic structure body and 32 inches in cycle ₁Between the figure of relation.(b) figure of Fig. 7 is to illustrate having spacing P ₁The spacing and the spacing P of the fashionable interference stripes that produce of FHD liquid crystal panel set of periodic structure body and 40 inches in cycle ₁Between the figure of relation.

Fig. 8 is the synoptic diagram that possesses the cross-section structure of the liquid crystal indicator under the situation of optically thin membranous part.

Fig. 9 is the process flow diagram of an embodiment that the manufacturing approach of light diffusing sheet involved in the present invention is shown.

Figure 10 (a) figure is the synoptic diagram of an example of the manufacturing installation of light diffusing sheet.Figure 10 (b) figure is the partial enlarged drawing of region alpha of (a) figure of Figure 10.

Figure 11 illustrates the implementation condition of embodiment 1～14 and comparative example 1～5 and the chart of evaluation result.

Figure 12 illustrates embodiment 11,13,15,16 and the implementation condition of comparative example 6,7 and the chart of evaluation result.

Embodiment

Below, with reference to accompanying drawing embodiment of the present invention is described.To similar elements mark same-sign, and the explanation that will repeat is omitted in the explanation of accompanying drawing.The dimension scale of accompanying drawing may not be consistent with illustrated structure.

Fig. 1 is the stereographic map of structure of an embodiment of schematically illustrated liquid crystal indicator involved in the present invention.Fig. 2 is the synoptic diagram of the cross-section structure that goes out of the II-II line of liquid crystal indicator shown in Figure 1.

Liquid crystal indicator 1 is the LCD of so-called full run-down type.The back light system (planar light source device) 20 that liquid crystal indicator 1 possesses liquid crystal panel 10 and liquid crystal panel 10 supplied with illumination light.In following explanation, for liquid crystal indicator 1, liquid crystal panel 10 sides are also referred to as the front side, and back light system 20 sides are also referred to as rear side or rear side.For the ease of explanation, will be called the z direction towards the direction (thickness direction of liquid crystal panel 10) of liquid crystal panel 10 sides from back light system 20, as shown in Figure 1, will be called x direction and y direction with the direction of z direction quadrature.

Liquid crystal panel 10 has: the liquid crystal cells 12 that comprises a plurality of pixels 11 (with reference to Fig. 2); And a pair of polarization plate 13,14, this a pair of polarization plate 13,14 clips liquid crystal cells 12 from both sides on the thickness direction of liquid crystal cells 12.As liquid crystal cells 12, for example can use known liquid crystal cells such as TFT type liquid crystal cells based on driven with active matrix.As the type of drive of liquid crystal panel 10, can use known modes such as VA mode, IPS mode and TN mode.In Fig. 1 and structure shown in Figure 2, because polarization plate 13 is positioned at back light system 20 sides, so the surperficial 13a of polarization plate 13 becomes the plane of incidence of illumination light to liquid crystal panel 10.

Back light system 20 possesses: the resinous lamp box 30 that front face side is opened wide; As a plurality of light sources 40 of light source portion, these light sources 40 are arranged in the lamp box 30; Light diffusing sheet 50, this light diffusing sheet 50 is arranged on the lamp box 30, and the peristome of lamp box 30 is stopped up.Here, though a plurality of light source 40 is corresponding with light source portion, lamp box 30 can be used as the part of light source portion.

Lamp box 30 constitutes through erectting the side wall portion 32 that four jiaos of frame shapes are set integratedly at the circumference of tabular bottom wall portion 31.Lamp box 30 is slim case shape.As shown in Figure 1, a plurality of light sources 40 that are arranged in the lamp box 30 for example are linear light source.In the present embodiment, as long as do not do things first explanation, be that linear light source describes then with light source 40.The linear light source that uses as light source 40 for example is fluorescent tube (cold-cathode tube), Halogen lamp LED, the so cylindric lamp of tungsten lamp.The diameter of such linear light source for example is 2mm～4mm.Here, though light source 40 is a linear light source, light source 40 is not limited to linear light source, also can be point source of light.Point source of light for example is a light emitting diode (LED).At light source 40 is under the situation of point source of light, also can use light source 40 as full run-down type shown in the image pattern 2 suchly.

The structure of the light diffusing sheet 50 that next, back light system 20 is had describes.Fig. 3 is the stereographic map of structure of an embodiment of schematically illustrated light diffusing sheet involved in the present invention.Fig. 4 is the synoptic diagram along the cross-section structure of the IV-IV line of Fig. 3.For the ease of explanation, utilize x direction shown in Figure 1, y direction and z direction, describe based on the state of such configuration light diffusing sheet 50 as shown in Figure 1 structure light diffusing sheet 50.

Light diffusing sheet 50 is that plan view shape is a quadrangle and have the tabular body of photopermeability roughly.Light diffusing sheet 50 is like Fig. 3 and shown in Figure 4, the double-deck light diffusing sheet that to be substrate layer 51 build up on the thickness direction upper strata according to the order of back layer 52, substrate layer 51 from rear side with back layer 52.

With the gross thickness T of the thickness t of substrate layer 51 1 and the light diffusing sheet 50 of the thickness t 2 addition gained of back layer 52 for example is 0.1mm～10mm.The thickness t 1 of substrate layer 51 for example is 0.05mm～9mm.The thickness t 2 of back layer 52 for example is 0.03mm～1mm.Raw material to light diffusing sheet 50 is not done particular determination, can use known translucent resin.

The example of the refractive index of translucent resin is 1.46～1.62.The example of translucent resin is acrylic resin, phenylethylene resin series, polycarbonate, tygon, polypropylene, cyclic polyolefin, cyclic olefin copolymer, polyethylene terephthalate, MS resin (copolymer of methyl methacrylatestyrene resin), polystyrene resin, AS resin (acrylonitritrile-styrene resin resin) etc.

As the Resin A of the raw material of substrate layer 51, can be the same or different with resin B as the raw material of back layer 52.Resin A and resin B can be used the above-mentioned translucent resin that illustrates for example separately separately, also can be respectively the material that above-mentioned resin combination more than 2 kinds is formed.Preferably, the combination of the translucent material that is combined as identical type of Resin A and resin B.More preferably, Resin A, B all contain phenylethylene resin series.Particularly preferably, Resin A and resin B all only are made up of phenylethylene resin series.

Light diffusing sheet 50 can contain the light diffusing agent of light diffusion particle and so on.The refractive index of light diffusing agent is different with the translucent resin that constitutes light diffusing sheet 50, and light diffusing agent does not have particular determination so long as the particle of the light diffusion that sees through at light diffusing sheet 50 get final product.The light diffusing agent of mineral-type for example is lime carbonate, barium sulphate, titanium dioxide, hydrate of aluminium, silicon, glass, talcum, mica, white carbon, magnesium oxide, zinc paste etc.Can be with utilizing fatty acid etc. that the light diffusing agent that illustrates is for example implemented surface treatment and material as light diffusing agent.Organic type light diffusing agent for example is styrenic particle, acrylic acid series polymeric compounds particle, siloxane-based polymers particle etc.Preferably, organic type light diffusing agent be weight average molecular weight be 500,000～5,000,000 high molecular polymer particle, or the gel fraction when being dissolved in acetone be the above cross-linking polymer particles of 10 quality %.

Contain at light diffusing sheet 50 under the situation of light diffusing agent, the blending ratio of light diffusing agent does, with respect to translucent resin 100 weight portions, light diffusing agent is 0.01～1 weight portion, and being more preferably light diffusing agent is 0.001～0.01 weight portion.The raw material of light diffusing agent and main composition light diffusing sheet 50, be to be used as masterbatch (master batch) after the translucent resin combination.Consider that from the viewpoint of light diffusing the absolute value of the difference of the refractive index of the translucent resin of the main material of light diffusing sheet 50 and the refractive index of light diffusing agent is 0.01～0.20, more preferably 0.02～0.15.

Can also add adjuvants such as ultraviolet light absorber, thermal stabilizer, anti-oxidant, weather resisting agent, light stabilizer, fluorescer, processing stabilizers to light diffusing sheet 50.

Ultraviolet light absorber is that ultraviolet light absorber, benzophenone series ultraviolet light absorber, triazine are that ultraviolet light absorber, benzotriazole are ultraviolet light absorber for phenyl salicytate for example.Adding under the situation of ultraviolet light absorber, with respect to the main material of light diffusing sheet 50, be translucent resin 100 weight portions, ultraviolet light absorber for example can add 0.1～3 weight portion.If be in this scope, then can suppress ultraviolet light absorber and ooze out (bleed), and can keep the outward appearance of light diffusing sheet 50 well to the surface.

Thermal stabilizer for example is manganese compound, copper compound etc.Thermal stabilizer for example can add with ultraviolet light absorber.In this case,, can add the thermal stabilizer below 2 weight portions, more preferably, can add thermal stabilizer with the ratio of 0.01～1 weight portion with respect to 1 weight portion of the ultraviolet light absorber in the translucent resin.

Anti-oxidant for example is hindered phenol compound, hindered amine compound.With respect to translucent resin 100 weight portions, for example can add the anti-oxidant of 0.1～3 weight portion.

At back layer 52 and surfaces substrate layer 51 opposition sides (second face) 50a that light diffusing sheet 50 is had, it is whole and roughly be distributed with fine recess or protuberance (below be called jog) equably to spread all over the surface.Surface 50a is so-called delustring face (matte).The a plurality of fine jog that is formed at surperficial 50a for example can be processed to form through embossing (emboss).The surface configuration that can come presentation surface 50a with the surfaceness of the arithmetic average roughness Ra that utilized surperficial 50a and 10 mean roughness Rz.As the example of the arithmetic average roughness Ra of surperficial 50a, for example for being the value that benchmark is measured with ISO-1997, and be 0.5 μ m～25 μ m, be preferably 1 μ m～20 μ m.As the example of 10 mean roughness Rz of surperficial 50a, for example for being the value that benchmark is measured with ISO-1997, and be 5 μ m～110 μ m, be preferably 10 μ m～100 μ m.Surface 50a also can be the surface of satisfying the above-mentioned value that illustrates for example as Ra and Rz simultaneously.

Be formed with a plurality of protuberances 53 substrate layer 51 with surfaces back layer 52 opposition sides (first face) 50b.Each protuberance 53 extends along y direction (first direction).A plurality of protuberances 53 are arranged in x direction (with direction, the second direction of bearing of trend quadrature).In other words, a plurality of protuberances 53 form the muscle shape on the surface of substrate layer 51.The cross sectional shape with y direction (bearing of trend) quadrature of each protuberance 53 for example is a semicircle shape.In this case, each protuberance 53 is the cylindrical lens shape.

As shown in Figure 4, a plurality of protuberances 53 can have d [μ m] at interval between adjacent protuberance 53.If each other distance of the center of adjacent protuberance 53 (below be called spacing) is made as P ₁[μ m], then height ha of protuberance 53 [μ m] and spacing P ₁Ratio (ha/P ₁) for example be 0.2～0.8., have constant interval d between the adjacent protuberance 53 here, also can be d=0 though be set in.In this case, P ₁Width corresponding to protuberance 53.Above-mentioned spacing P ₁Mean P ₁The spacing of [μ m].Such mark be for after state other spacing differentiate.In the following description, also other spacing is adopted same mark sometimes.

Gone under the situation of liquid crystal indicator 1 (with reference to Fig. 1) the spacing P of protuberance 53 by group at light diffusing sheet 50 ₁Determined to become to be difficult to the value that Visual Confirmation goes out interference stripes.Below, to spacing P ₁The condition that is satisfied describes.

At first utilize (a) figure of Fig. 5, (b) figure of Fig. 5, (c) figure of Fig. 5 and (d) of Fig. 5 to scheme the generation of interference stripes is described.Fig. 5 (a) figure is the synoptic diagram of liquid crystal indicator 1 shown in Figure 1.In Fig. 5 (a) figure, schematically the surperficial 50a with light source 40 sides of light diffusing sheet 50 illustrates as tabular surface.Fig. 5 (b) figure is the synoptic diagram of the periodic structure of the interference stripes that produce of the periodic structure because of light diffusing sheet 50 and liquid crystal panel 10.(c) figure of Fig. 5 is the synoptic diagram of the transmittance curve of liquid crystal panel 10.(d) figure of Fig. 5 is the synoptic diagram of the transmittance curve of light diffusing sheet.

Since a plurality of protuberances 53 on the x direction with spacing P ₁Arrangement, so a plurality of protuberances 53 side by side has the cycle on the x direction be P ₁Periodic structure.Utilize S1=E ₁Cos (2 π (x/P ₁)) represent transmittance curve S1 based on this periodic structure." E in the formula ₁" amplitude of expression transmittance curve S1.

Liquid crystal panel 10 comprises a plurality of pixels 11.A plurality of pixels 11 are arranged on x direction and y direction regularly.Therefore, liquid crystal panel 10 has constant periodic structure on x direction and y direction.When the spacing with the pixel 11 of the x direction of liquid crystal panel 10 (orientation of a plurality of protuberances 53 or with the direction of the bearing of trend quadrature of protuberance 53) is made as P _p[μ m] (but, P _p≠ P ₁And 0.5P _p≠ P ₁) time, utilize S2=E ₂Cos (2 π (x/P _p)) represent the transmittance curve S2 based on the periodic structure of x direction of liquid crystal panel 10." E in the formula ₂" amplitude of expression transmittance curve S2.When the picture dimension with the x direction of liquid crystal 10 is made as L (μ m) and the pixel count of x direction is made as N (N is the integer more than 1), can be with P _p(μ m)=L/N representes spacing P _p

In liquid crystal indicator 1, spacing P ₁Periodic structure and spacing P _pPeriodic structure overlapping at above-below direction.Therefore, see through light diffusing sheet 50 and liquid crystal panel 10 and the contrast S based on above-mentioned periodic structure of the light that obtains is represented by S=S1 * S2.Here, S1 * S2 is shown in following formula.

$\mathrm{<figure-callout\; id="1"\; label="S"\; filenames="HSA00000609744800011.png,HSA00000609744800021.png"\; state="\{\{state\}\}">S</figure-callout>}1\&CenterDot;\mathrm{<figure-callout\; id="2"\; label="S"\; filenames="HSA00000609744800111.png"\; state="\{\{state\}\}">S</figure-callout>}2=\frac{A\&CenterDot;\mathrm{<figure-callout\; id="2"\; label="B"\; filenames="HSA00000609744800111.png"\; state="\{\{state\}\}">B</figure-callout>}}{2}\&CenterDot;\left[\cos \right\{2\mathrm{\&pi;x}/\left(\frac{P_p\&CenterDot;P_l}{P_p+P_l}\right)\}+\cos \{2\mathrm{\&pi;x}/\left(\frac{P_p\&CenterDot;P_l}{\left|P_p{-P}_l\right|}\right)\left\}\right]\&CenterDot;\&CenterDot;\&CenterDot;\left(5\right)$

Shown in (b) figure of formula (5) and Fig. 5, contrast S comprises radio-frequency component and low-frequency component.High article composition is not looked because of frequency is high to be recognized, and low-frequency component is looked and recognized as so-called interference stripes.Therefore, as formula (5) based on spacing P _pPeriodic structure and spacing P ₁The spacing P of interference stripes of periodic structure _m1 [μ m] represented by formula (6).Below, also the spacing with interference stripes is called the interference stripes spacing.

${\mathrm{<figure-callout\; id="1"\; label="P\; m"\; filenames="HSA00000609744800011.png,HSA00000609744800021.png"\; state="\{\{state\}\}">P</figure-callout>}}_{m}1=\frac{P_p\&CenterDot;P_l}{|P_p-P_l|}\&CenterDot;\&CenterDot;\&CenterDot;\left(6\right)$

Present inventors constantly study, and the result finds: in liquid crystal panel 10, transmitance is sometimes with (1/2) pel spacing, promptly with 0.5P _pChange.Fig. 6 illustrates transmitance with 0.5P _pOne example of situation about changing.Fig. 6 is FHD (the Full High Definition that illustrates with 32 inches of VA mode activated with 200 times; Full HD) liquid crystal panel 10 time the figure of pixel image.X direction among Fig. 6 and y direction are corresponding to x direction and y direction among Fig. 1～Fig. 3 etc.

Can think this 0.5P _pThe cause in cycle be because wide viewing angleization, near the alignment direction difference of the liquid crystal molecule central authorities of the x direction in a pixel 11.Though Fig. 6 is the situation of VA pattern, the situation of IPS pattern too.Under the situation of IPS pattern, can think 0.5P _pThe cause in cycle be because comb poles, near the alignment direction difference of the liquid crystal molecule central authorities of the x direction in a pixel 11.

As stated, also comprise cycle 0.5P at liquid crystal panel 10 _pThe situation of periodic structure under, follow in the spacing P of the interference stripes of this periodic structure _m2 [μ m] are represented by formula (7).

${\mathrm{<figure-callout\; id="2"\; label="P\; m"\; filenames="HSA00000609744800111.png"\; state="\{\{state\}\}">P</figure-callout>}}_{m}2=\frac{0.5P_p\&CenterDot;P_l}{|0.5P_p-P_l|}\&CenterDot;\&CenterDot;\&CenterDot;\left(7\right)$

(a) figure of Fig. 7 and (b) figure of Fig. 7 are to illustrate having spacing P ₁Transparent periodic structure body and the spacing and the spacing P of the fashionable interference stripes that produce of liquid crystal panel set in cycle ₁Between the figure of relation.(a) figure of Fig. 7 and (b) of Fig. 7 illustrate actual measured value.Obtain actual measured value in the following manner.In the liquid crystal indicator (liquid crystal TV set) of the liquid crystal panel with 32 inches FHD and 40 inches FHD, above-mentioned periodic structure body is disposed between light source portion and the liquid crystal panel.Under this configuration status, through carrying out in the darkroom, observing interference fringe under the state that white shows at above-mentioned each liquid crystal indicator, thereby the spacing of interference stripes is measured.Under the situation of Fig. 7 (a) figure, use 32 inches liquid crystal panel, under the situation of Fig. 7 (b) figure, use 40 inches liquid crystal panel.

In Fig. 7 (a) figure and Fig. 7 (b) figure, " " illustrates employing with the light diffusing sheet of the actual manufacturing of the translucent resin result as the situation of above-mentioned periodic structure body.On the other hand, " zero " illustrates light diffusing sheet model (replica) that employing makes with the silicon result as the situation of above-mentioned periodic structure body.Though the raw material of periodic structure body is different as stated, it is identical with light diffusing sheet shown in Figure 3 that the shape of periodic structure body forms.In Fig. 7 (a) figure and Fig. 7 (b) figure, the P by formula (6) expression is shown with solid line _m1 with respect to P ₁Variation, the P by formula (7) expression shown in broken lines _m2 with respect to P ₁Variation.

Shown in (b) figure of Fig. 7 (a) figure and Fig. 7, the size of actual measured value and liquid crystal panel 10 irrespectively is mapped on the curve of being represented by formula (6) and formula (7).That is, be appreciated that to having produced and spacing P based on liquid crystal panel 10 _pPeriodic structure and spacing P ₁The different interference stripes of interference stripes of periodic structure.According to (a) figure of Fig. 7 and (b) figure of Fig. 7, can understand: the P that utilizes formula (6) and formula (7) to calculate _m1 and P _m2, corresponding to having spacing P ₁The interference stripes that produced during with liquid crystal panel 10 combinations of the light diffusing sheet 50 of periodic structure.

In light diffusing sheet 50, spacing P ₁Be to make P _m1 satisfies P _m1＜1500 μ m and make P _m2 satisfy P _mThe value of 2＜1500 μ m.

P _m1 and P _mThe 2nd, light diffusing sheet 50 that kind as shown in Figure 1 are equipped on the spacing of the interference stripes that liquid crystal indicator 1 occurs now and then.In light diffusing sheet 50, will be so that spacing P _m1 and spacing P _m2 all set P less than the mode of 1500 μ m ₁Therefore, when liquid crystal indicator 1 is driven, be difficult to look and recognize interference stripes.Such spacing P ₁For example be more than the 30 μ m and below the 700 μ m.In the scope shown in giving an example, spacing P ₁Be preferably more than the 50 μ m and below the 500 μ m, more preferably more than the 150 μ m and below the 400 μ m.

Looked the viewpoint of recognizing from further inhibition interference stripes and considered between light diffusing sheet shown in Figure 8 50 and liquid crystal panel 10, to possess optically thin membranous part 60.Fig. 8 is the synoptic diagram that possesses the cross-section structure of the liquid crystal indicator 1 under the situation of optically thin membranous part.Among Fig. 8, show optically thin membranous part 60 for example and have the situation of 3 optical thin films 61.Can be so that the haze value H (%) of optically thin membranous part 60 satisfies kind and the number that the mode of 95≤H≤99.9 selects to constitute the optical thin film 61 of optically thin membranous part 60.Haze value H is total haze value of the full optical thin film 61 of the optically thin membranous part 60 of formation.Haze value H is to be the value of benchmark survey mensuration with JIS-K7136 (ISO 14782).

Optical thin film 61 for example is diffusion film, prism film, reflective polarizing light separating film, phase-contrast film and polarized light film etc.The optical thin film that optically thin membranous part 60 can have an above identical type overlaps the structure that forms, and perhaps can have the structure that a plurality of different types of optical thin films coincidences form more than.Here, to as the example of optical thin film 61 and each film of enumerating describe.

Diffusion film is the film that is used for the light diffusion irradiation of incident.As an example of diffusion film, there is the structure on a side's who utilizes bonding agent pearl to be fixed in transparent resin film surface.As the object lesson of diffusion film, comprise " the D121U series " of Tsujiden Co., Ltd. (TUSJIDEN) manufacturing and " the diffusion barrier TM " of Co., Ltd. woody (KIMOTO) manufacturing etc.

Prism film is for example for being formed with the film of a plurality of optically focused property lens on the surface of a side that is disposed at liquid crystal panel 10.Each optically focused lens extends to a direction.A plurality of optically focused property lens with the direction of the bearing of trend quadrature of optically focused property lens on configuration side by side.Fine optically focused property lens for example comprise laterally convex lens and the biconvex lens (lenticular lens) of protrusion etc.Fine optically focused property lens can also be that the cross section is leg-of-mutton prism.

Reflective polarizing light separating film is following film: the polarized light of regulation is seen through, and will have the polarized light reflection of the character opposite with the polarized light of this regulation.The example of reflective polarizing light separating film can be enumerated: make the rectilinearly polarized light of certain vibration direction see through and make the reflection-type rectilinearly polarized light separating film with the rectilinearly polarized light reflection of the direction of vibration of this certain vibration direction quadrature; And the circularly polarized light that makes the sense of rotation of regulation sees through and makes the reflection-type circularly polarized light separating film of the circularly polarized light reflection of rotating to the direction opposite with the sense of rotation of regulation etc." DBEF (the Dual Brightness Enhancement Film that the example of reflection-type rectilinearly polarized light separating film has Sumitomo 3M Co., Ltd. to make; Reflective polaroid) ", " NIPOX " of Nitto Denko Corp's manufacturing.

Phase-contrast film is to have the phase differential that the extension because of resin film produces (to lag behind; Retardation) film.Phase-contrast film for example is polycarbonate based resin film, polysulfones based resin film, polyether sulfone resin film, polyarylate based resin film, norbornene resin film." ELMEC " and " SUMIKARAIT " of Sumitomo Chemical Co's manufacturing that the object lesson of phase-contrast film has Kanegafuchi Chemical Ind to make.

Polarized light film is the film that makes the light transmission that on fixed-direction, vibrates." NPF " and " SUMIKARAN " of Sumitomo Chemical joint-stock company manufacturing that the object lesson of polarized light film has eastern electrician of day joint-stock company to make.

[manufacturing approach of light diffusing sheet]

Next, the example to the manufacturing approach of the light diffusing sheet of this embodiment describes.Light diffusing sheet 50 forms a plurality of protuberances 53 through a surface at resin sheet, and the resin sheet that will be formed with protuberance 53 then is cut into the size of regulation and processes.As shown in Figure 9, the manufacturing approach of light diffusing sheet 50 has design should obtain light diffusing sheet 50 by the design process S10 of a plurality of protuberances 53 of figuration and with the protuberance that is designed 53 figurations in resin sheet the S20 of manufacturing process.Fig. 9 is the process flow diagram that the manufacturing approach of light diffusing sheet is shown.Below, each operation is described.

< design process >

In design process S10, decide the spacing P1 of protuberance 53 based on pel spacing Pp and formula (6) with formula (7), and determine by the relief pattern that should be constituted in a plurality of protuberances 53 of light diffusing sheet 50 by figuration with the liquid crystal panel 10 of light diffusing sheet 50 combination.Here, designed finish (for example being semicircle shape) and described, also can in this design process S10, design the cross sectional shape of protuberance 53 though be set at the cross sectional shape of each protuberance 53.

< manufacturing process >

In the S20 of manufacturing process, utilize the manufacturing installation 80 of light diffusing sheet shown in (a) figure of Figure 10 to make resin sheet 70, and with the surperficial 70a of the protuberance that is designed 53 figurations in this resin sheet 70.Manufacturing installation 80 to light diffusing sheet shown in Figure 10 50 describes.

Manufacturing installation 80 possesses: sheet forming machine 90, this sheet forming machine 90 are that resin extruded is molded into sheet with raw material; One group of compression roller crowd 100, this group of compression roller crowd 100 makes resin sheet 70 further moulding through pushing the resin sheet 70 that is squeezed out; And extract with roller crowd 110, this extraction is used to extract resin sheet 70 with roller crowd 110.

Sheet forming machine 90 possesses: the raw material that first extruder 91, this first extruder 91 are used for substrate layer 51 is the Resin A heating and melting; The raw material that second extruder 92, this second extruder 92 are used for back layer 52 is the resin B heating and melting; Feed member 93, this feed member 93 is supplied with by the resin of first extruder 91 and 92 fusions of second extruder; And punch die (die) 94, this punch die 94 is extruded the resin in the feed member 93 with the sheet material state.Hopper 95,96 in first and second extruder 91,92 is equipped with the cylinder that is used for resin is dropped into extruder.

Compression roller crowd 100 has 3 compression rollers 101,102,103.3 compression rollers 101～013 are respectively columned metallic roller.The rotation of each compression roller 101～103 is parallel to each other.In the embodiment shown in Figure 10 (a) figure, 3 compression rollers 101～103 dispose in vertical direction continuously, and the rotation of 3 compression rollers 101～103 is level.Here, though describe based on the embodiment shown in Figure 10 (a) figure, the mode shown in (a) that the configuration relation of 3 compression rollers 101～103 is not limited to Figure 10 schemes.For example, compression roller 101～103 can dispose in the horizontal direction continuously.The turning axle of 3 compression rollers 101～103 is connected with the driver element of motor (not shown) and so on respectively.

The side face 101a of compression roller 101 is an even surface.On the other hand, on the side face 102a as the compression roller 102 of intermediate calender rolls between compression roller 101 and the compression roller 103, be provided with delustring transfer mold 104, this delustring transfer mold 104 is used to form the surperficial 50a that possesses micro concavo-convex portion shown in Figure 3.The surface of delustring transfer mold 104 is following delustring face: spreaded all over integral body and roughly distributed equably by the embossing shape that constitutes with the opposite pattern of desiring to form at surperficial 50a of relief pattern.As the arithmetic average roughness Ra of this delustring face, for example be to be the value that benchmark is measured with ISO-1997, be 6 μ m～30 μ m, as 10 mean roughness Rz, for example be to be the value that benchmark is measured with ISO-1997, be 45 μ m～150 μ m.In Figure 10 (a) figure, on the side face 103a as the compression roller 103 of lower roll of the downside that is positioned at compression roller 102, be provided with the intaglio plate transfer mold 105 that is used to form protuberance 53.On intaglio plate transfer mold 105, along compression roller 103 circumferentially be formed with many and muscle shape be the groove of reverse mutually with protuberance 53.That is,, has the roughly profile of semicircle arcuation, the spacing P that is designed among the distance between the center of adjacent groove (spacing) and the design process S10 with the cross section of its length direction (circumferentially) quadrature for groove ₁Corresponding.

Delustring transfer mold 104 also can be arranged at compression roller 103, the compression roller 102 in the middle of intaglio plate transfer mold 105 also can be arranged at.The side face 102a of compression roller 102 also can be even surface.In this case, the surperficial 50a of the rear side of light diffusing sheet 50 is an even surface.

Can adopt the raw material of organic material as above-mentioned delustring transfer mold 104 and intaglio plate transfer mold 105.As the organic material of the raw material of delustring transfer mold 104 and intaglio plate transfer mold 105, even so long as have and be pushed on the resin sheet 70 that has just squeezed out from punch die 94 times without number and also can keep the stable on heating material of the shape of transfer mold and get final product with the heating and melting state.Organic material for example is thermosetting resin and thermoplastic resin etc.

Through utilizing driver element that compression roller 101 and compression roller 103 are rotated counterclockwise; And compression roller 102 is turned clockwise, and compression roller crowd 100 can be on one side implements processing to the two sides of the resin sheet 70 that squeezes out from sheet forming machine 90 and resin sheet 70 is carried out moulding on one side.

Extract and have a pair of extraction with roller 111,112 with roller crowd 110.Extract with roller 111,112 and on the thickness direction of resin sheet 70, sandwich resin sheet 70 from both sides.Extract and be respectively columned metallic roller with roller 111,112.Shown in Figure 10 (a) figure, a pair of extraction is arranged to and can be carried out horizontal feed to resin sheet 70 with the state of keeping the height after resin sheet 70 just seen off from compression roller 103 with roller 111,112.

Next, utilize Fig. 9 and Figure 10 that the S20 of manufacturing process manufacturing installation 80, light diffusing sheet 50 that has used light diffusing sheet 50 is described.As shown in Figure 9, the S20 of manufacturing process comprises that the S21 of sheet material manufacturing process, transfer printing process S22 and light diffusing sheet form operation S23.

(1) S21 of sheet material manufacturing process

The raw material that drops into substrate layers 51 to the hopper of first extruder 91 95 is a Resin A.First extruder 91 after with the Resin A melting mixing, the Resin A after feed member 93 is supplied with melting mixing.The raw material that drops into back layer 52 to the hopper of second extruder 92 96 is a resin B.Second extruder 92 after with the resin B melting mixing, the resin B after feed member 93 is supplied with melting mixing.The cylinder temperature of first extruder 91 and second extruder 92 for example is approximately 190～250 ℃.Next, punch die 94 is together extruded the resin in the feed member 93.Thus, shown in (b) figure of Figure 10, double-deck resin sheet 70 is squeezed out from punch die 94.Figure 10 (b) figure is the partial enlarged drawing of region alpha of (a) figure of Figure 10.In the embodiment shown in Figure 10 (a) figure, the layer 71 of the downside in the resin sheet 70 that is squeezed out is the layer that should become back layer 52, and the layer 72 of upside is the layer that becomes substrate layer 51.

(2) transfer printing process S22

The resin sheet 70 that is squeezed out from punch die 94 is sandwiched between compression roller 101 and the compression roller 102 and is extruded, and then is transferred accordingly with the rotation of compression roller 102.At this moment, resin sheet 70 is cooled.Owing to be provided with delustring transfer mold 104 at compression roller 102, therefore when compression roller 101 and compression roller 102 extrusion resin sheet materials 70, the shape of delustring transfer mold 104 is needed on the surperficial 70b of resin sheet 70 and forms a plurality of fine jogs.Preferably, the surface temperature of compression roller 101 and compression roller 102 is lower than the extrusion temperature of resin sheet 70, and the surface temperature of compression roller 101 and compression roller 102 for example is approximately 50 ℃～120 ℃.

After being extruded roller 101 and compression roller 102 extruding conveyings, resin sheet 70 is sandwiched between compression roller 102 and the compression roller 103 and is extruded.Thus, the surface configuration of intaglio plate transfer mold 105 is needed on the surperficial 70a of resin sheet 70.Its result forms many and the muscle shape and the parallel protuberance of flow direction resin sheet 70 (transport direction) at surperficial 70a.The surface temperature of compression roller 103 for example is 50 ℃～120 ℃.

Resin sheet 70 as above-mentioned be extruded after roller 102 and compression roller 103 sandwich and be extruded, be transferred with the state of the side face of being close to compression roller 103, and then seen off from the lower end edge horizontal direction of compression roller 103.

(3) light diffusing sheet forms operation S23

Through utilizing a pair of extraction to extract resin sheets 70 with roller 111,112, producing at two surperficial figurations up and down has the resin sheet 70 of regulation shape.After resin sheet 70 is further cooled, is cut into the size (regulation zone) of expectation, thereby obtains light diffusing sheet 50.Usually; Because light diffusing sheet 50 is when being equipped on liquid crystal indicator 1; 4 limits are pushed by resin system or metal framework and are assembled into liquid crystal indicator 1, thus light diffusing sheet 50 cut out the picture dimension big circle of size than the liquid crystal indicator 1 that supplies its lift-launch.

Utilize the light diffusing sheet 50 that above-mentioned manufacturing approach can shop drawings 3 and Fig. 4 illustrated for example.As shown in Figure 1, when the light diffusing sheet made from this mode 50 was equipped on back light system 20 and liquid crystal indicator 1, light diffusing sheet 50 was arranged to opposed and peristome stopped up with the bottom wall portion of lamp box 30 31 on lamp box 30.At this moment, with the design conditions that is adopted among the design process S10 light diffusing sheet 50 and liquid crystal panel 10 are configured.Especially, light diffusing sheet 50 is configured to liquid crystal panel 10: spacing is P ₁The orientation and the spacing of protuberance 53 be P _pPixel 11 direction of arranging consistent.At light source 40 is under the situation of linear light source, and light diffusing sheet 50 is configured to liquid crystal panel 10: the bearing of trend of light source (linear light source) 40 and the bearing of trend of protuberance 53 roughly consistent (being the y direction among Fig. 1).

If the light source 40 of back light system 20 is lighted, then from the light of light source 40 outputs directly after light diffusing sheet 50 incidents or surface reflection, to light diffusing sheet 50 incidents in the bottom wall portion 31 of lamp box 30.Because a plurality of protuberances 53 form the muscle shape on the surperficial 50b of liquid crystal panel 10 sides of light diffusing sheet 50, therefore when light when the light diffusing sheet 50 of light transmission penetrates, light with penetrate the position accordingly to various directions ejaculations.Thus, spread from the light of light source 40, thereby penetrated as planar light from the light of light source 40.Owing to utilize this planar rayed liquid crystal panel 10, therefore can utilize the driving of liquid crystal panel 10 to come display image.

The spacing P of the protuberance 53 of light diffusing sheet 50 ₁Be following value: for the spacing P shown in formula (6) and the formula (7) _m1 and spacing P _m2, make P _m1 satisfies P _m1＜1500 μ m and make P _m2 satisfy P _m2＜1500 μ m.The spacing that therefore, might be equipped on the interference stripes that produce under the situation of liquid crystal indicator 1 at light diffusing sheet 50 is less than 1500 μ m.Its result is difficult to Visual Confirmation and goes out interference stripes, can improve the image quality by liquid crystal panel 10 images displayed.

In this embodiment, with the spacing P of protuberance 53 ₁Decision is: make the interference stripes spacing P shown in formula (6) and the formula (7) _m1 and interference stripes spacing P _m2 equal less than 1500 μ m.Therefore, spacing P ₁Be decided to be: not only can suppress because with spacing P ₁For the periodic structure in cycle with pel spacing P _pBe the interference stripes that the periodic structure in cycle produces, can also suppress and 0.5P based on the present inventor had in mind _PThe interference stripes that accompany of the periodic structure of spacing (1/2 pel spacing).Therefore, through being P to pel spacing _p Liquid crystal panel 10 use light diffusing sheets 50, can also suppress Visual Confirmation and go out because of alignment direction to cut apart the caused interference stripes of transmitance variation that cause based on 1/2 pel spacing based on the liquid crystal molecule of liquid crystal panel 10.

And then shown in (b) figure of Fig. 7 (a) figure and Fig. 7, formula (6) and formula (7) are corresponding with the spacing of the interference stripes of actual generation.Its result is through based on the P by formula (6) and formula (7) defined _m1 and P _m2 decide P ₁, can make interference stripes be difficult for being looked recognizing more reliably.

As Fig. 8 for example shown in, when the optically thin membranous part 60 of the satisfied 95≤H of haze value H (%)≤99.9 is set, more can cover interference stripes between light diffusing sheet 50 and liquid crystal panel 10.Under the situation that optically thin membranous part 60 is set as stated, for example do not rely on the distance (even for example near liquid crystal panel 10) between liquid crystal panel 10 and the observation place and make interference stripes be difficult for being looked recognizing.

Be difficult for more being looked the state of recognizing in order to become interference stripes, preferably with P ₁Be designed so that P _m1 and P _m2 are in respectively below the 1000 μ m.In this case, even aforesaid optically thin membranous part 60, or the above-mentioned condition of haze value H (%) unmet of optically thin membranous part 60 are not set,, therefore also be difficult for seeing interference stripes because the spacing of the interference stripes that produced is in below the 1000 μ m.

Preferably, for the spacing P of the pixel 11 in the orientation (the x direction of Fig. 1) of protuberance 53 _pBe in the liquid crystal panel 10 that 440 μ m are above and the scope below the 535 μ m is interior, use spacing P ₁Be in more than the 325 μ m and the light diffusing sheet 50 of the scope below the 335 μ m.Its reason is, the spacing P of any value more than with 325 μ m and below the 335 μ m ₁Form a light diffusing sheet 50 of protuberance 53, group is gone into pel spacing P _pWhen being the liquid crystal panel 10 that 440 μ m are above and 535 μ m are following,, all can reduce looking the possibility of recognizing interference stripes with any liquid crystal panel 10 combinations in this scope.In this case, in manufacturing installation 80, owing to change the necessity reduction of the compression roller 103 that is formed with the intaglio plate transfer mold according to each liquid crystal panel that varies in size 10, so can reduce the production cost of liquid crystal indicator 1.

As above illustrated; According to the embodiment of the present invention, can provide along a plurality of optical element portion that the direction of regulation is extended and form parallel to each other and can suppress the light diffusing sheet of interference stripes, the manufacturing approach of light diffusing sheet, the liquid crystal indicator that possesses the planar light source device of light diffusing sheet and possess light diffusing sheet more reliably.

[embodiment]

Next, describe based on embodiment and comparative example action effect light diffusing sheet.Below, for the ease of the explanation, in comparative example 1～7, also with embodiment 1～16 together to giving identical label with the corresponding key element of above-mentioned embodiment.

In embodiment 1～16 and comparative example 1～7, prepared to have the liquid crystal indicator 1 of the liquid crystal panel 10 of prescribed level, spacing P ₁Different light diffusing sheets 50 is equipped on this liquid crystal indicator 1, in the darkroom, recognizes evaluation to when carrying out the white demonstration, having or not interference stripes to look.

The spacing P of the pixel 11 of employed liquid crystal panel 10 and each liquid crystal panel 10 in each embodiment 1～16 and comparative example 1～7 _PRespectively shown in the chart among Figure 11 and Figure 12.Figure 11 illustrates the implementation condition of embodiment 1～14 and comparative example 1～5 and the chart of evaluation result.Figure 12 illustrates embodiment 11,13,15,16 and the implementation condition of comparative example 6,7 and the chart of evaluation result.As previously mentioned, the FHD among Figure 11 and Figure 12 is the abbreviation of aforesaid Full High Definition.WXGA is the abbreviation of WideeXtended Graphics Array.In the chart of Figure 11 and Figure 12, " 32 inches " etc. simply are expressed as " 32 " ".

Make that the manufacturing approach of raw material and light diffusing sheet of employed light diffusing sheet in each embodiment 1～16 and the comparative example 1～7 is identical.Raw material, the manufacturing installation of light diffusing sheet and the optically thin membranous part that suitably uses to constituting employed resin sheet as light diffusing sheet 50 in embodiment 1～16 and the comparative example 1～7 describe.

< raw material of resin sheet >

As the raw material of resin sheet 70, prepare to have the raw material of following (1) and (2).

(1) translucent resin A

Styrene resin (Japan styrene Co., Ltd. makes " HRM40 " refractive index 1.59)

(2) translucent resin B

Styrene resin (Japan styrene joint-stock company makes " HRM40 " refractive index 1.59)

< manufacturing installation of light diffusing sheet >

Manufacturing installation 80 shown in (a) figure of use Figure 10 has been made the light diffusing sheet 50 of embodiment 1～16 and comparative example 1～7.Compression roller 101～103 for the compression roller crowd 100 who constitutes manufacturing installation 80 uses following roller.

For compression roller 101, the diameter that uses side face 101a to be carried out after the mirror finish is the metallic roller of 450mm.

For compression roller 102, use the metallic roller of diameter as 450mm.Side face 102a at compression roller 102 is provided with delustring transfer mold 104.

For compression roller 103, use the metallic roller of diameter as 450mm.Side face 103a at compression roller 103 is provided with intaglio plate transfer mold 105.

< optically thin membranous part >

Optically thin membranous part 60 is made up of 3 optical thin films 61.Employed optical thin film 61 is diffusion film.Particularly, use the D121UY/D121UY/D121UZ of Tsujiden Co., Ltd.'s manufacturing in order successively from the optical thin film 61 of light diffusing sheet 50 sides.Total mist degree of these 3 diffusion films, the haze value H of promptly optically thin membranous part 60 is 99.2%.In addition, use HM-150 that dye technology research institute of Murakami K. K. makes and carry out the mensuration of haze value H with JIS-K7136 (ISO 14782) as benchmark.

Likewise embodiment 1～16 and comparative example 1～7 are made light diffusing sheet 50 with the manufacturing approach that (a) figure that utilizes Fig. 9 and Figure 10 is illustrated.That is, Resin A and resin B are supplied with by the feed member 93 to double-deck distribution type after being 190 ℃～250 ℃ first extruder 91 and second extruder, 92 melting mixing by the temperature in the cylinder respectively.Dropped into first extruder 91 and the translucent resin A of second extruder 92 and the amount of translucent resin B respectively and be 100 weight portions.

Then, the resin in the feed member 93 is extruded jointly and is formed double-deck resin sheet 70 from punch die 94 with 250 ℃ extrusion resin temperature.At this moment, become substrate layer 51 and carry out co-extrusion with the resin of supplying with to feed member 93 from first extruder 91 from the mode that the resin that second extruder 92 is supplied with to feed member 93 becomes back layer 52.Then, passed through compression roller crowd 100 as aforementioned by the resin sheet 70 of coextrusion.Thus; Produce width 1300mm, gross thickness T and be 2.0mm (thickness t 1 of substrate layer 51 is 1.95mm, and the thickness t 2 of back layer 52 is 0.05mm) and be formed with a plurality of protuberance 53 on the surperficial 70a, on surperficial 70b, be formed with fine concavo-convex resin sheet 70.At this moment, set for: the surface temperature of compression roller 101 is 65 ℃, and the surface temperature of compression roller 102 is 77 ℃, and the surface temperature of compression roller 103 is 98 ℃.The speed of production of resin sheet 70 is the 4.7m/ branch.The size back that the resin sheet 70 that produces like this is cut into regulation obtains light diffusing sheet 50.

In above-mentioned manufacturing approach, through as intaglio plate transfer mold 105, in other words i.e. as compression roller 103 and suitably use and Figure 10 and each embodiment 1～16 shown in Figure 11 and the spacing P of comparative example 1～7 ₁Corresponding structure can obtain the light diffusing sheet 50 corresponding to each embodiment 1～16 and comparative example 1～7.With the size of the light diffusing sheet 50 of each embodiment 1～16 and comparative example 1～7, be set in each embodiment 1～16 and comparative example 1～7 big or small corresponding with employed liquid crystal panel 10 during interference stripes are estimated.Therefore, under the situation that the 10 pairs of interference stripes of liquid crystal panel that use identical size are estimated, the size of light diffusing sheet 50 is also identical.

< interference stripes evaluation method >

The light diffusing sheet 50 that to be prepared to each embodiment 1～16 and comparative example 1～7 constitutes liquid crystal indicator 1 (with reference to Fig. 2 or Fig. 8) with Figure 11 and liquid crystal panel 10 combinations shown in Figure 12.Light source 40 in each liquid crystal indicator 1 is a linear light source.And, carry out that white shows and in the darkroom from positive and obliquely confirm to have or not interference stripes through visual.The driving method of liquid crystal panel 10 such as Figure 11 and shown in Figure 12.In addition, change light diffusing sheet 50 this point, utilize the same terms that interference stripes are estimated except liquid crystal panel 10 to identical size.

(evaluation method of embodiment 1～14 and comparative example 1～5)

For embodiment 1～14 and comparative example 1～5,, under the state that is not equipped with optically thin membranous part 60, interference stripes have been confirmed as the structure of liquid crystal indicator shown in Figure 11.Its result, even looked under the situation of recognizing at the part interference stripes, carry optically thin membranous part 60 shown in Figure 8 after, once more to having or not interference stripes to confirm.

(evaluation method of embodiment 15,16 and comparative example 6,7)

For embodiment 15,16 and comparative example 6,7, for through comparing with embodiment 11,13 and the versatility of light diffusing sheet 50 is estimated, just confirm having or not interference stripes from beginning at first with the state that is equipped with optically thin membranous part 60.

< interference stripes evaluation result >

Be distinguished into Figure 11 and situation shown in Figure 12 describes the interference stripes evaluation result.In Figure 11 and Figure 12, P _m1 and P _m2 is the P with each embodiment 1～16 and comparative example 1～7 _pAnd P ₁Bring the value of formula (6) and formula (7) gained into.In Figure 11 and Figure 12, P _m1 and P _m2 illustrate back two by the numerical value after rounding up.In the hurdle of " interference stripes evaluation ", recognize interference stripes and then illustrate if look with " * ", do not recognize interference stripes and then illustrate if look with " zero ".

(interference stripes evaluation result shown in Figure 11)

Can understand at P ₁Be designed to make P _m1 and P _m2 all among the embodiment below 1000 μ m 1～3,5～7,9,10,14, recognizes interference stripes even under the state that optically thin membranous part 60 is not set, also look.If study in the situation that will possess optically thin membranous part 60 is also included within, then under the situation of the light diffusing sheet 50 that has used embodiment 1～14, according to spacing P ₁And P _pThe P that derives _m1 and P _m2 less thaies, 1500 μ m.In other words, in the light diffusing sheet 50 of embodiment 1～14, spacing P ₁Be configured to make P _m1 and P _m2 less thaies, 1500 μ m.In this case, shown in figure 11 be interpreted as not look recognize interference stripes.Its result has confirmed to obtain the situation of the display performance of excellent in uniformity.

On the other hand, in the light diffusing sheet 50 of comparative example 1～5, P _m1 and P _m2 the such condition of arbitrary side's unmet less than 1500 μ m.In this case, can understand situation shown in Figure 11: also look and recognized interference stripes even possess optically thin membranous part 50.If consider this point, then can understand: in embodiment 4,8,11～13, interference stripes are suppressed to the degree that can cover interference stripes through possessing optically thin membranous part 60.

(interference stripes evaluation result shown in Figure 12)

In embodiment 15,16, P _m1 and P _m2 also less than 1500 μ m.In other words, in the light diffusing sheet 50 of embodiment 15,16, spacing P ₁Be configured to make P _m1 and P _m2 less thaies, 1500 μ m.In this case, shown in figure 12, do not look and recognize interference stripes.Its result has confirmed to obtain the situation of the display performance of excellent in uniformity.Shown in figure 12, the spacing P of embodiment 11,13,15,16 _pBe in the scope that 440 μ m are above and 535 μ m are following the spacing P of embodiment 11,13,15,16 ₁Be more than the 325 μ m and below the 335 μ m.Under the situation of the embodiment that satisfies such condition 11,13,15,16, the spacing P of pixel 11 no matter _pDifference how, all through spacing P ₁(in embodiment 11,13,15,16, P ₁=330 μ m) realize the visible distance that is difficult for of interference stripes.On the other hand, in comparative example 6,7, P _pFrom more than the 440 μ m and the scope below the 535 μ m break away from, be 364 μ m.In this case, even spacing P ₁For with identical spacings such as embodiment 11, also look and recognized interference stripes.

In Figure 12, owing to utilize embodiment is classified with the combination of liquid crystal panel 10, therefore be divided into embodiment 11,13,15,16.Yet, because spacing P ₁Identical, so the structure of light diffusing sheet 50 self is also identical in embodiment 11,13,15,16.Therefore, can understand:, utilize 1 light diffusing sheet 50 just can realize the minimizing of interference stripes regardless of the size difference of liquid crystal panel 10.

More than, embodiment of the present invention and embodiment are illustrated, but the present invention is not limited to above-mentioned embodiment and embodiment, in the scope of the purport that does not break away from invention, can carry out various changes.

In above-mentioned explanation, though the optical element portion that light diffusing sheet 50 had for example is protuberance 53, optical element portion also can be recess.And then, though protuberance 53 such optical element portions are formed at the surperficial 50b of liquid crystal panel 10 sides, also can be formed at surperficial 50a, can also be formed at surperficial 50a and surperficial 50b both sides.Though light diffusing sheet is illustrated as double-deck light diffusing sheet, light diffusing sheet also can be single layer structure, can also have the layer structure more than 3 layers.And then, though show semicircle for example,, do not do particular determination as long as protuberance 53 has the shape of the diffusion that can produce light diffusing sheet 50 as the cross sectional shape of protuberance 53.

Though show linear light source for example as light source 40, also can use the such point source of light of light emitting diode.Under the situation of having used optically thin membranous part 60, the haze value H of the optically thin membranous part 60 shown in giving an example is more than 95% and below 99.9%.Yet, as long as the haze value H of optically thin membranous part 60 be more than 90% and 99.9% below, as long as and then be more than 80% and 99.9% following.In addition, consider that from suppressing to look the viewpoint of recognizing interference stripes it is high more good more to be preferably lower limit.

Claims (13)

1. light diffusing sheet is arranged at the plane of incidence side of liquid crystal panel, wherein,

Possess first of said liquid crystal panel side with said first opposed second at least one square a plurality of optical element portion that becomes,

Each said optical element portion extends along first direction,

A plurality of said optical element portion with the roughly configuration side by side on the second direction of quadrature of said first direction,

Making the spacing of a plurality of said optical element portions on said second direction is P ₁, the pel spacing of a plurality of pixels on said second direction that said liquid crystal panel is had is P _p, and P _p≠ P ₁And 0.5P _p≠ P ₁, making the interference stripes spacing based on the interference stripes of the periodic structure of a plurality of said optical element portions on said second direction is P _m1, making the interference stripes spacing based on the interference stripes of the periodic structure of a plurality of said pixels on said second direction is P _m2, said P ₁, P _p, P _m1, P _m2 unit is μ m, when utilizing formula (1) and formula (2) expression P respectively _m1 and P _m2 o'clock,

$P_{m}1=\frac{P_p\&CenterDot;P_l}{|P_p-P_l|}\&CenterDot;\&CenterDot;\&CenterDot;\left(1\right)$

$P_{m}2=\frac{0.5P_p\&CenterDot;P_l}{|0.5P_p-P_l|}\&CenterDot;\&CenterDot;\&CenterDot;\left(2\right)$

Said P ₁For making said P _m1 satisfies P _m1＜1500 μ m and said P _m2 satisfy P _mThe value of 2＜1500 μ m.

2. light diffusing sheet according to claim 1, wherein,

Said P ₁For making said P _m1 satisfies P _m1≤1000 μ m and said P _m2 satisfy P _mThe value of 2≤1000 μ m.

3. light diffusing sheet according to claim 1 and 2, wherein,

Said P _pBe below the above 535 μ m of 440 μ m,

Said P ₁Be below the above 335 μ m of 325 μ m.

4. according to each described light diffusing sheet in the claim 1～3, wherein,

The width of the said liquid crystal panel on making said second direction is that the unit of L and this L is μ m, to make the quantity of the said pixel on the said second direction be N and N when being the integer more than 1,

Said P _pRepresent by L/N.

5. according to each described light diffusing sheet in the claim 1～4, wherein,

Said optical element portion is a protuberance.

6. a planar light source device is supplied with light to liquid crystal panel, and said planar light source device possesses:

Output is towards the light source portion of the illumination light of said liquid crystal panel; And

Be arranged at each described light diffusing sheet in the claim 1～5 between said light source portion and the said liquid crystal panel.

7. liquid crystal indicator, this liquid crystal indicator possesses:

Liquid crystal panel;

Output is towards the light source portion of the illumination light of said liquid crystal panel; And

Be arranged at each described light diffusing sheet in the claim 1～5 between said light source portion and the said liquid crystal panel.

8. liquid crystal indicator according to claim 7, wherein,

Also between said liquid crystal panel and said light diffusing sheet, possess the optically thin membranous part that comprises at least one optical thin film,

The haze value H of said optically thin membranous part satisfies 95%≤H≤99.9%.

9. the manufacturing approach of a light diffusing sheet; It is the method for making following light diffusing sheet; Said light diffusing sheet is arranged at the plane of incidence side of liquid crystal panel, and have with the second direction of first direction quadrature on dispose the surface of the optical element portion that the said first direction in a plurality of edges extends side by side

The manufacturing approach of said light diffusing sheet comprises:

To a plurality of said optical element portion with respect to the spacing P on the said second direction ₁The operation that [μ m] designs; And

Through based on the said P that is designed ₁Form the operation that a plurality of said optical element portion makes said light diffusing sheet on one of the tabular body surface that has permeability and become said light diffusing sheet,

At the said spacing P of design ₁Said operation in, in said liquid crystal indicator, said liquid crystal panel is disposed under the situation of said light diffusing sheet, the pel spacing of a plurality of pixels on said second direction that said liquid crystal panel is had is P _p, and P _p≠ P ₁And 0.5P _p≠ P ₁, making the interference stripes spacing based on the interference stripes of the periodic structure of a plurality of said optical element portions on said second direction is P _m1, making the interference stripes spacing based on the interference stripes of the periodic structure of a plurality of said pixels on said second direction is P _m2, said P ₁, P _p, P _m1, P _m2 unit is μ m, when utilizing formula (3) and formula (4) expression P respectively _m1 and P _m2 o'clock,

$P_{m}1=\frac{P_p\&CenterDot;P_l}{|P_p-P_l|}\&CenterDot;\&CenterDot;\&CenterDot;\left(3\right)$

$P_{m}2=\frac{0.5P_p\&CenterDot;P_l}{|0.5P_p-P_l|}\&CenterDot;\&CenterDot;\&CenterDot;\left(4\right)$

With said P ₁Decision is for making said P _m1 satisfies P _m1＜1500 μ m and said P _m2 satisfy P _mThe value of 2＜1500 μ m.

10. the manufacturing approach of light diffusing sheet according to claim 9, wherein,

To said spacing P ₁In the said operation that designs,

With said P ₁Determine to become to make said P _m1 satisfies P _m1≤1000 μ m and said P _m2 satisfy P _mThe value of 2≤1000 μ m.

11. according to the manufacturing approach of claim 9 or 10 described light diffusing sheets, wherein,

Said P _pBe more than the 440 μ m and below the 535 μ m,

Said P ₁Be more than the 325 μ m and below the 335 μ m.

12. according to the manufacturing approach of each described light diffusing sheet in the claim 9～11, wherein,

The width of the said liquid crystal panel on making said second direction is that the unit of L and this L is μ m, to make the quantity of the said pixel on the said second direction be N and N when being the integer more than 1,

Said P _pRepresent by L/N.

13. according to the manufacturing approach of each described light diffusing sheet in the claim 9～12, wherein,

The said operation of making said light diffusing sheet comprises:

Make operation through extrusion modling as the resin sheet of said tabular body;

To a surface of said resin sheet, push the said spacing P that has as transfer mold with to be designed ₁The roller of the mould that a plurality of said optical element portion of configuration is opposite, thus said transfer mold is needed on the operation on a said surface; And

Thereby the regulation zone that will form the said resin sheet of a plurality of said optical element portion through said transfer mold transfer printing and on a said surface cuts out the operation that forms said light diffusing sheet.

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