KR20110082134A - An optical sheet, a manufacturing method of the optical sheet, and a light source device and a display device including the optical sheet - Google Patents

Abstract

In a liquid crystal display panel, an optical sheet and a method for manufacturing the same, and an optical sheet capable of improving the luminance ratio at the intermediate point between the line light sources arranged parallel to each other and directly above the light source, and obtaining a uniform brightness distribution, and directly below A light source device and a liquid crystal display device are provided. The optical sheet of the present invention is an optical sheet having a convex lens group formed on a surface in a linear ridge shape, and the convex portion outer periphery of all the lenses in a vertical cross-sectional shape with respect to the longitudinal direction of the lens group is A part X ₁ composed of a curve and / or a straight line, wherein the tangent and / or angle between the straight line and the base line at all points on the curve is θ ≧ 40 °, and all the points on the curve. An optical sheet comprising a portion (X ₂ ) having an angle (θ) formed between a tangent line at a point and / or the straight line and the base line at 25 ° ≦ θ ≦ 35 ° at a predetermined ratio.

Description

Optical sheet, manufacturing method of the optical sheet, and light source device and display device including the optical sheet {OPTICAL SHEET, OPTICAL SHEET MANUFACTURING METHOD, LIGHT SOURCE INCLUDING OPTICAL SHEET, AND DISPLAY DEVICE}

The present invention relates to an optical sheet, a method for manufacturing the optical sheet, a light source device including the optical sheet, and a display device.

In recent years, the display device has changed from using a CRT to using a liquid crystal, and the screen has also been enlarged. As a light source of the liquid crystal display device, there are an edge light method and a direct type light source, but in a large liquid crystal display device, a direct type light source in which a plurality of cold cathode tubes are arranged as a light source is generally used.

On the screen of the liquid crystal display using the direct light source, the portion where the cold cathode tube exists is bright, but the portion where the cold cathode tube does not exist is relatively dark, and the luminance deviation occurs that the cold cathode tube is reflected on the screen. There is. Therefore, by disposing various optical sheets between the cold cathode tube and the liquid crystal panel, it is performed to uniformly diffuse the light generated from the cold cathode tube over the entire screen.

The liquid crystal display device is required to be thinner, and for this purpose, the distance between the cold cathode tube and the screen has to be narrowed, and it is difficult to diffuse the light from the cold cathode tube sufficiently. Further, in order to lower costs, it has been attempted to reduce the number of cold cathode tubes, and it is difficult to uniformly diffuse the light from the cold cathode tubes with the expansion of the cold cathode tubes. Therefore, under such strict conditions, as a method of eliminating the luminance deviation and improving the luminance, selecting an optical sheet provided with a lens in the optical sheet disposed at the position closest to the light source and adjusting the lens shape is performed. . In addition, at least one prism sheet is selected from the viewpoint of luminance from the light source to the optical sheet disposed after the second in the direction from the light source to the liquid crystal panel side. In the combination of a plurality of optical sheets, the problem is firstly to resolve the luminance deviation that the part where the cold cathode tube is present is bright but the part where the cold cathode tube does not exist is relatively dark, and secondly, the lens This is to solve the new luminance deviation due to the low luminance portion in the immediate vicinity of the cold cathode tube generated by using the diffusion sheet and the prism sheet having the?.

In order to make the luminance distribution uniform while preventing a decrease in the illumination efficiency, for example, in the direct type light source devices disclosed in Patent Documents 1 and 2, a prism sheet having a plurality of prism lenses having a triangular cross section and a convex surface A lenticular lens sheet in which a plurality of cylindrical lenses, which are cylindrical surfaces, are provided together is used as a substitute for a conventional optical sheet. Since the prism sheet or the lenticular lens sheet has a smaller number of times that the incident light beam repeats the reflection refraction compared with the optical sheet using the conventional type of light diffusing agent, the amount of transmitted light can be prevented and the luminance in the viewing angle direction can be prevented. Can improve. However, although prism sheet can improve brightness, there is a limit to the uniformity of its distribution. Although the lenticular lens sheet can improve the uniformity of the luminance distribution more than the prism sheet, it is difficult to eliminate the luminance deviation completely under the strict cold cathode tube installation conditions as described above.

Japanese Laid-open Patent Publication H10-283818 Japanese Unexamined Patent Publication No. 2004-006256

At least one prism sheet is placed on an optical sheet having a lens arranged in a straight ridge shape on the light exiting surface at a position closest to the light source, and placed second or later in the direction of the liquid crystal panel side from the light source. By using the light or the like, the light diffusivity can be enhanced by the effect of the prism, and the front luminance can be increased. Therefore, it is considered that it is the structure of the optical sheet for light sources suitable for thinning a liquid crystal television and reducing the number of cold cathode tubes.

However, such an optical sheet configuration can originally diffuse sufficient light between cold cathode tubes having low brightness, but since light having a small incident angle from the optical sheet to the prism sheet is returned to the optical sheet by the prism sheet, Cancer lines occur in Even if the pattern of the cold cathode tube can be erased, since this dark line remains, new luminance deviation occurs.

Moreover, in order to reduce a new cost, it is calculated | required to reduce the number of optical sheets used for a light source device. Here, when the number of sheets of the optical sheet is reduced, a new problem arises that not only the luminance deviation is more difficult to be solved, but also the image of the pin supporting the optical sheet in the backlight unit appears.

SUMMARY OF THE INVENTION An object of the present invention is to reduce the luminance deviation at the intermediate point between the linear light sources (for example, cold cathode tubes) and the linear light source directly above (directly above), and second from the light source to the liquid crystal panel side. The present invention provides an optical sheet capable of obtaining a uniform luminance distribution by a combination with an optical sheet to be arranged later, a manufacturing method of the optical sheet, a light source device and a liquid crystal display device including the same.

In order to solve the above problems and problems of the prior art, the inventors conducted intensive research and found that in the lens group formed in the form of a straight ridge on the surface of the optical sheet, all of the lens groups in the vertical cross-sectional shape with respect to the longitudinal direction of the lens group were found. The above-mentioned problem is solved by adjusting the ratio of the portion where the outer peripheral line of the convex portion of the lens is composed of a curve and / or a straight line, and the angle between the tangent line and / or the straight line and the base line of the curve is within a specific range. I discovered something and came to complete the invention.

That is, the optical sheet of the present invention is an optical sheet having a convex lens group formed on the surface in a straight ridge shape, and the outer peripheral lines of the convex portions of all the lenses in the vertical cross-sectional shape with respect to the longitudinal direction of the lens group are curved and And / or a portion X ₁ composed of a straight line and having an angle θ formed by a tangent line at all points on the curve and / or the straight line and the base line at θ ≧ 40 °, and at all points on the curve. A length x that includes a portion X ₂ having a tangent and / or an angle θ formed by the straight line and the base line of 25 ° ≦ θ ≦ 35 °, and projecting on the baseline of the lens group of the part X ₁ . ₁ ) total (x _1total ) is 25% or more and 60% or less of the total (P _total ) of the baseline length of the lens group, and the length (x ₂₎ projected on the baseline of the lens group of the portion (X ₂ ). X _{2 total} is greater than or equal to 25% and greater than 60% of the _total length (P _total ) of the baseline length of the lens group. It is characterized by servants.

In the first embodiment of the present invention, the lens group has a convex portion outer peripheral line in a vertical cross-sectional shape with respect to the longitudinal direction of the unit lens mainly composed of a curve, and a tangent at all points on the curve. baseline and the angle (θ ₁₁₎ is θ ₁₁ ≥40 ° the curved portion (R _11), and is 25 ° ≤θ ≤35 ₁₂ angle (θ ₁₂₎ forming the tangent and baseline in all points on the curve A curve portion R ₁₂ , which is °°, wherein the ratio of the total length r ₁₁ of the length R _{11 of} the curve portion R ₁₁ to the base line of the unit lens shape is 25% or more and 60%. The first unit lens having a ratio of the total length r ₁₂ of the length R ₁₂ projected to the base line of the unit lens shape of the curved portion R _{12 to} the full length of the base line is 25% or more and 60% or less (Fig. Optical sheet).

In the second embodiment of the present invention, the lens group has a convex portion outer periphery in a vertical cross-sectional shape with respect to the longitudinal direction of the unit lens, in which two or more curves and one or more straight lines are connected. At least two of the curves include a curved portion R ₂₁ whose angle θ ₂₁ between the tangent and the base line at all points on the curve is θ ₂₁ ≧ 40 °, wherein the straight line R ₂₂ and the base line are forming an optical member having an angle (see FIGS. 7 to 10) (θ ₂₂₎ is 25 ° ≤θ ₂₂ ≤35 ° of the second lens unit.

According to a third embodiment of the present invention, the lens group has a unit lens (see Fig. 12) having a shape 1 below and a unit lens having a shape 2 as a convex portion outer periphery of a vertical cross-sectional shape with respect to the longitudinal direction. 13).

`` Shape 1 ''

The part whose outer periphery consists of a curve or a straight line, and the angle (theta) ₃₂ which the tangent or straight line in all the points on the curve, and the base line of the unit lens cross-sectional shape is 25 degrees <= _{32 32} < R ₃₂ ), and the total length r ₃₂ of the portion R ₃₂ projected on the base line of the unit lens cross-sectional shape is 90% or more with respect to the base line length of the unit lens cross-section. .

`` Shape 2 ''

The outer periphery is composed mainly of the curved portion, and the sum total of the length (r ₃₃ ) projected on the baseline of the unit lens shape of the portion (R ₃₃ ) represented by a single secondary curve is applied to the baseline overall length of the unit lens shape. 90% or more, and as part of the portion R ₃₃ , the curved portion R ₃₁ having an angle θ ₃₁ formed by the tangent line and the base line at all points on the curve is θ ₃₁ ≧ 40 °. And the ratio of the total length r ₃₁ of the length R _{31 of} the portion R ₃₁ to the base line of the lens cross-sectional shape is 20% or more.

The present invention also includes a display device including a manufacturing method of the optical sheet, a light source device for a display device which requires the optical sheet and a prism sheet, and a light source device for the display device.

By using the optical sheet of the present invention, the luminance in the viewing angle direction in the region immediately above the line light source of the light source device and the luminance in the viewing angle direction in the intermediate region of the adjacent line light source are independently adjusted. It becomes possible. Therefore, in various device settings (device configuration, light source device conditions, combination with an optical sheet other than the present invention), high brightness uniformity on the light exit surface side in the setting is realized.

1 is a schematic diagram illustrating a configuration of a display device.
FIG. 2 is a view showing a second embodiment as an optical sheet of the present invention. FIG.
3 is a view showing a third embodiment as an optical sheet of the present invention.
It is explanatory drawing of the name of each part of the optical sheet of 1st Embodiment.
It is explanatory drawing of the name of each part of the optical sheet of 2nd Embodiment.
6 is an explanatory view of an example of a first unit lens surface shape design concept.
7 is an explanatory diagram of an example of a second unit lens shape.
8 is an explanatory diagram of an example of a second unit lens shape.
9 is an explanatory diagram of an example of a second unit lens shape.
10 is an explanatory diagram of an example of a second unit lens shape.
It is explanatory drawing of the name of each part of the optical sheet of 3rd Embodiment.
12 is an explanatory diagram of one example of a unit lens cross-sectional shape 1. FIG.
13 is an explanatory diagram of an example of a unit lens cross-sectional shape 2. FIG.
FIG. 14 is an explanatory diagram of an example of a model faced to face to form a surface shape that can be used in the manufacturing method of the optical sheet of the first and second embodiments.
FIG. 15 is an explanatory diagram of an example of a confronted model for forming a surface shape that can be used in the method for manufacturing the optical sheet of the third embodiment. FIG.
16 is an explanatory diagram of a first unit lens surface shape in Examples 1 to 6. FIG.
17 is an explanatory diagram of a first unit lens surface shape in Example 7. FIG.
18 is an explanatory diagram of a first unit lens surface shape in Example 8. FIG.
19 is an explanatory diagram of a first unit lens surface shape in Example 9. FIG.
20 is an explanatory diagram of a first unit lens surface shape in Example 10. FIG.
21 is an explanatory diagram of a first unit lens surface shape in Example 11. FIG.
22 is an explanatory diagram of an example of a first unit lens surface shape in Examples 12 and 13. FIG.
23 is an explanatory diagram of a lens group of the optical sheet of Example 14;
24 is an explanatory diagram of a lens group of the optical sheet of Comparative Example 5. FIG.
25 is an explanatory diagram of a lens group of the optical sheet of Example 27;
FIG. 26 is an explanatory diagram of one example of a unit lens cross-sectional shape 1 in Examples 28 to 33. FIG.
27 is an explanatory diagram of one example of a unit lens cross-sectional shape 2 in Examples 28 to 35. FIG.
28 is an explanatory diagram of one example of a unit lens cross-sectional shape 1 in Examples 34 and 35. FIG.
29 is an explanatory diagram of a lens group of the optical sheets of Examples 28 to 33;
It is explanatory drawing of the arrangement | positioning of the support pin in the direct type light source device used in the Example.

Although it demonstrates below with reference to drawings etc., this invention is not limited only to embodiment of drawing. The 1st optical sheet in this specification means the optical sheet arrange | positioned 1st with respect to the direction of a liquid crystal panel side from a light source, and the 2nd or later optical sheet is arrange | positioned 2nd, 3rd, and 4th, respectively. The optical sheet of a sequence is shown (refer FIG. 1). In addition, the optical sheet closest to a front panel corresponds to the 4th optical sheet of the code | symbol 6 in FIG. There is no upper limit of the number of sheets if these optical sheets can be achieved without causing any detrimental factors (e.g., significant increase in thickness, increase in cost) of the purpose of installation (e.g., brightness enhancement). .

First, the physical configuration such as the surface shape of the optical sheet according to the present invention will be described, followed by the chemical composition, the method of combining other sheets, and the device configuration.

1. Surface shape of the optical sheet of the present invention

The optical sheet of the present invention is an optical sheet having a convex lens group formed on the surface in a straight ridge shape, wherein the outer peripheral lines of the convex portions of all the lenses in the vertical cross-sectional shape with respect to the longitudinal direction of the lens group are curved and / or A part X ₁ composed of a straight line and having a tangent at all points on the curve and / or an angle θ formed by the straight line and the base line at θ ≧ 40 ° and at all points on the curve. A length x that includes a portion X ₂ having a tangent and / or an angle θ formed by the straight line and the base line of 25 ° ≦ θ ≦ 35 °, and projecting on the baseline of the lens group of the part X ₁ . The total length (x _1total ) of ₁ ) is 25% or more and 60% or less of the _total P length of the baseline length of the lens group, and the length (projected onto the baseline of the lens group of the portion X ₂ ) the total (x _2total) of x ₂₎ 25% of the total number (P _total) of the baseline length of the lens That the 60% or less characterized.

By setting the total (x _1total ) and the total (x _2total ) in the above ranges, the light from the light source can be sufficiently diffused in the middle portion of the cold cathode tube row, and the luminance in the viewing angle direction in the middle portion is improved. You can. Further, in order to increase the luminance in the viewing angle direction, even when an optical sheet such as a prism sheet or a diffusion sheet having a lens, which can be generally used in the optical sheet of the present invention is superimposed, the luminance of the cold cathode tube region can be sufficiently secured. Can be.

In addition, although the straight line as used in this invention refers to the straight line segment which connects the terminal mutually, the curve which has the extremely small curvature which the line segment which connects a terminal part is almost near a straight line is included. Moreover, although the curve used in this invention differs from a straight line, the curve which has a small curvature near a straight line is also included. Although the minimum structural unit defined in the present invention is a micron order, when the micron order is observed, for example, when the vertical section of the optical sheet is observed with an electron microscope or the like, the curved portion defined in the present invention is the order. In the case of a curve having a small curvature that is difficult to judge as a low curve, the determination is performed as follows, for example. For a straight line of length A connecting two points on the curve with the shortest distance, the value of 100 x d / A may exceed 1 when the point on the curve that is farthest from the straight line is the shortest distance d of the straight line. In the case of a curve, it determines with a curve, and when a value of 100xd / A is 1 or less, it determines with a straight line.

In addition, in this invention, a minimum part is the lowest point of the outer periphery of the convex part of a unit lens. The base line is a straight line connecting the lowest part with the lowest part. The top portion is the highest point from the base line in the outer circumference of the convex portion of the unit lens.

The portion X ₁ has an angle θ formed between a tangent line at all points on the curve and / or the straight line and the base line, θ ≧ 40 °. As the portion X ₁ , for example, the curved portion R ₁₁ of the first unit lens, the curved portion R ₂₁ of the second unit lens, and the curved portion R ₃₁ of the unit lens having the shape 2 will be described later. Is applicable. That is, the length (x ₁₎ includes, for example, the amount of projecting the area (X ₁₎ of the first unit lens to be described later to the baseline length (r _11), the portion of the second unit lens (X ₁₎ This corresponds to the total amount r ₂₁ of the length projected to the base line, and the total length r ₃₁ of the length X ₃₁ of the projected portion X ₁ of the unit lens having the shape 2 to the base line.

It said portion (X ₂₎ is a tangent and / or the angle (θ) is the straight line and the baseline achieve in all points on the curve 25 ° ≤θ≤35 °. Examples of the portion X ₂ include a curved portion R ₁₂ of the first unit lens, a straight portion R ₂₂ of the second unit lens, a portion R ₃₂ of the unit lens having a shape 1, and the like. The portion R ₃₄ of the unit lens having the shape 2 corresponds. That is, the length (x ₂₎ as, for example, the total number of the projected length of said portion (X ₂₎ of the first unit lens to be described later to the baseline (r _12), the portion of the second unit lens (X ₂₎ the amount of the projection length of the baseline (r _22), the shape 1 total number of units of the projected length of said portion (X ₂₎ of the lens to a baseline having a (r _32), the portion of the unit lens has a shape 2 (X ₂ ) is the total length r ₃₄ of the projection of the baseline.

Further, in the optical sheet of the present invention calculates, a length projected on the baseline of the lens with respect to a portion (X ₁₎ and a portion (X ₂₎ of the all lenses in the convex lens group formed on the surface. Accordingly, in the total (x _1total ) and the total (x _2total ), not only the first unit lens, the second unit lens, the unit lens having the shape 1 and the unit lens having the shape 2, but also the unit lens having another structure (For example, a lenticular shape) is also contemplated. That is, in 2nd embodiment mentioned later, as shown in FIG. 2, the total amount regarding a 2nd unit lens and a lenticular unit lens is calculated.

In the optical sheet of the present invention, these surface shapes are set on the light emitting surface side. On the other hand, the surface shape configuration on the light-incident surface side of the optical sheet of the present invention is not particularly limited, and can be appropriately selected from among surfaces having optical elements such as flat surfaces, emboss surfaces, matt surfaces, lenses, etc. An embossed surface and a mat surface are preferably used from the viewpoint of preventing the sound from sounding and exhibiting light scattering effect.

2. First Embodiment and Second Embodiment

In order to describe the first and second embodiments, a cross section (shape of a vertical cross section) perpendicular to the linear ridge direction (length direction of the lens) of the lens arranged in a linear ridge shape on the optical sheet will be described ( 4, 5). In the optical sheet according to the first embodiment of the present invention, the lens group has a first unit lens (see FIG. 6). In the optical sheet of the second embodiment of the present invention, the lens group has a second unit lens (see FIGS. 7 to 10).

2-1. First unit lens

In the first unit lens, the outer periphery of the convex portion in the vertical cross-sectional shape with respect to the longitudinal direction of the unit lens is mainly composed of a curve, and the angle between the tangent and the base line at all points on the curve is θ. ₁₁₎ θ ₁₁ ≥40 ° curved section ₍₁₁ R) and the angle (θ ₁₂₎ forming the tangent and baseline in all points on the curve 25 ° ≤θ ₁₂ ≤35 ° the curved section ₍₁₂ R ), And the ratio of the total length r ₁₁ of the total length r ₁₁ of the curved portion R ₁₁ projected to the base line of the unit lens shape is 25% or more and 60% or less, and the curve The ratio of the total length r ₁₂ of the length R ₁₂ projected to the base line of the unit lens shape of the negative R _{12 to} the total length of the base line is 25% or more and 60% or less.

The ratio of the total length r ₁₁ of the length projected on the baseline of the curved portion R ₁₁ to the baseline total length is 25% or more and 60% or less, and the length projected on the baseline of the curved portion R ₁₂ . By setting the ratio to the baseline electric field of the total amount of r ₁₂ to 25% or more and 60% or less, the light from the light source can be sufficiently diffused in the middle portion of the cold cathode tube row, and furthermore, the viewing angle direction in the middle portion. The brightness to can be improved. Furthermore, in order to raise the brightness | luminance of a viewing angle direction, even if it superimposes optical sheets, such as a prism sheet or a diffusion sheet provided with a lens, which can be generally used for the optical sheet of this invention, sufficient brightness | luminance of an area | region on a cold cathode tube is fully ensured. can do. Therefore, by using the optical sheet of the first embodiment, the distance between the line light source and the optical sheet due to further thinning, the number of the line light sources for reducing energy consumption and cost of the liquid crystal display device can be reduced. Increasing the line light source spacing by means of the liquid crystal display panel, which has become increasingly difficult to solve the luminance deviation, can solve the luminance deviation.

2-1-1. Curve

The curved portion (R ₁₁₎ is preferably part of the design is easy, workability, and, the second curve from the point of view of optical performance. In addition, the curved portion R ₁₁ may be a combination of one or two or more secondary curves, may be arranged symmetrically to the left and right of the convex portion outer periphery, or may be disposed asymmetrically. In addition, a secondary curve means an ellipse, a hyperbola, and a parabola including a circle. When the curved portion R ₁₁ is part of an ellipse, the eccentricity is preferably 0.50 or more and 0.95 or less, more preferably 0.70 or more and 0.93 or less, and still more preferably 0.80 or more and 0.90 or less.

The curved portion R ₁₂ may be part of a quadratic curve, similar to the curved portion R ₁₁ . However, the curved portion (R _12), yet has the narrow angle of the tangent of the tangent and the angle (θ ₁₂₎ that make the baseline in all points on the curve 25 ° ≤θ ₁₂ ≤35 °, In addition, the amount of the projection length of the baseline Since the ratio to the baseline electric field of (r ₁₂ ) needs to have a length of 25% or more and 60% or less, it is not necessarily necessary to be part of the quadratic curve, and any one or two or more of the above conditions are satisfied. It may consist of a curve. In addition, similarly to the curved portion R ₁₁ , the convex portion may be arranged symmetrically to the left and right of the outer peripheral line, or may be arranged asymmetrically.

The curve on the convex portion outer circumference line in the vertical cross-sectional shape with respect to the longitudinal direction of the first unit lens is composed of two or more kinds of segments including the curved portion R ₁₁ and the curved portion R ₁₂ , Among them, the ratio of the total length r ₁₁ of the length projected on the base line of the curved portion R _{11 to} the base line electric field is 25% or more and 60% or less. When the ratio r ₁₁ is less than 25%, light diffusion into the middle portion of the cold cathode tube row decreases, and the luminance in the viewing angle direction in the middle portion decreases, making it difficult to eliminate the luminance deviation. On the other hand, if the ratio of the total amount r ₁₁ exceeds 60%, the optical cathode, such as a prism sheet or a diffusion sheet with a lens, which can be generally used to increase the luminance in the viewing angle direction, is superimposed. The luminance is lowered, causing a new luminance deviation. The ratio of the total amount r ₁₁ is more preferably 27% or more and 58% or less, and more preferably 30% or more and 55% or less.

In addition, the ratio of the total length of the baseline amount (r ₁₂₎ of the projection length of the baseline of the curve section ₍₁₂ R) is 60% or less than 25%. When the ratio of the total r ₁₂ is less than 25%, in order to increase the luminance in the viewing angle direction, when the optical sheets such as a prism sheet or a diffusion sheet having a lens can be used in general, the luminance of the cold cathode tubular region is increased. It will fall and it will become difficult to eliminate a luminance deviation. On the other hand, when the ratio of the total amount r ₁₂ exceeds 60%, light diffusion into the middle portion of the cold cathode tube row decreases, and the luminance in the viewing angle direction in the middle portion decreases, making it difficult to eliminate the luminance deviation. The ratio of the total amount r ₁₂ is more preferably 27% or more and 58% or less, and more preferably 30% or more and 55% or less.

These two kinds of curved portions R ₁₁ and R ₁₂ can be directly connected to form a convex portion outer periphery, or a straight line or an angle θ ₁₃ formed between a tangent line and a base line at a point on the curved line. It may be connected through a curved portion R ₁₃ of 35 ° <θ ₁₃ <40 °, or θ ₁₃ <25 °. However, in order to increase the bacteria purifying the purpose luminance of the invention, it is a percentage of the baseline total length of the total length (r ₁₃₎ projected on the baseline of these junctions is more preferably 40% or less is preferable, 20% or less.

Further, connection to other of the curved portion (R ₁₁₎ and the curved portion (R ₁₂₎ can be a symmetric convex portion right and left outer peripheral line, and may be asymmetrical, the, more height by adjusting these connection methods The luminance deviation can be eliminated. The number of existence of the curved portion R ₁₁ and the curved portion R ₁₂ is not particularly limited as long as it satisfies the ratio of r ₁₁ and r ₁₂ , but preferably two each exists. The setting position of the curved portion R ₁₁ and the curved portion R ₁₂ may be close to the base portion. Wherein the curved portion (R ₁₁₎ is preferable because formability is close to the base surface. If there is the curved portion (R ₁₁₎ close to the base, is the position of the symmetry center line of the curved portion (R ₁₁₎ and curved portions (R ₁₂₎ a lens unit as a boundary are preferred from the viewpoint of formability.

2-2. 2nd unit lens

The second unit lens has a convex portion outer periphery in a vertical cross-sectional shape with respect to the longitudinal direction of the unit lens and has a shape in which two or more curves and one or more straight lines are connected, and at least two of the curves are The angle (θ ₂₁ ) between the tangent line and the base line at every point on the curve includes a curved portion (R ₂₁ ) with θ ₂₁ ≥40 °, and the angle (θ ₂₂ ) between the straight line (R ₂₂ ) and the base line is It is 25 ° ≤θ ₂₂ ≤35 °.

By setting the straight line, the number of curves, the position, the curve θ ₂₁ and the straight line θ ₂₂ of the convex portion peripheral line in the vertical section, the luminance in the viewing angle direction in the region immediately above the cold cathode tube of the light source device The luminance in the viewing angle direction in the intermediate region of the adjacent cold cathode tube can be independently adjusted. Therefore, high brightness uniformity of the entire light source device surface is realized in various device settings (light source device conditions, combination with an optical sheet other than the present invention).

The two or more curves and one or more straight lines are, for example, a unit lens structure having a convex portion outer periphery of a cross section as shown in FIGS. 7 to 10. The number of straight lines is preferably two or more in view of ease of manufacture of a model used for lens molding, ease of optical performance adjustment as a whole optical sheet, and the like.

2-2-1. Curve

The curve constituting the convex outer circumference of the second unit lens is preferably a part of a secondary curve such as an ellipse (including a circle) from the viewpoint of ease of design, processability, and optical performance, and one or two or more curves. It may be a combination of quadratic curves. When the curve on the outer periphery of the convex portion in the vertical cross-sectional shape with respect to the longitudinal direction of the second unit lens includes an ellipse (including a circle), the eccentricity is preferably 0.50 or more and 0.95 or less, and 0.70 or more and 0.93 or less. The following is more preferable, and 0.80 or more and 0.90 or less are more preferable.

The curve on the outer circumferential line of the convex portion in the vertical cross-sectional shape with respect to the longitudinal direction of the second unit lens is a curve whose angle (θ ₂₁ ) between the tangent and the base line at all points on the curve is θ ₂₁ ≧ 40 °. Part R ₂₁ is included. Here, the ratio of the total length r ₂₁ of the length projected on the base line of the curved portion R _{21 to} the base line electric field is preferably 25% or more and 60% or less. If the ratio r ₂₁ is less than 25%, light diffusion into the middle portion of the cold cathode tube row decreases, and the luminance in the viewing angle direction in the middle portion is decreased, making it difficult to eliminate the luminance deviation. On the other hand, if the ratio of the total amount r ₂₁ exceeds 60%, the optical cathode, such as a prism sheet or a diffusion sheet having a lens, which can be generally used to increase the luminance in the viewing angle direction, is superimposed on the cold cathode tube region. The luminance is lowered, causing a new luminance deviation. The ratio of the total amount r ₂₁ is more preferably 27% or more and 58% or less, and more preferably 30% or more and 55% or less.

In addition, the curve is an angle (θ ₂₃₎ and a tangent baseline in all points on the curve that forms on the second lens unit convex portion outer peripheral line of the vertical cross-section of the longitudinal direction of 25 ° ≤θ ₂₃ It may contain a curved portion R ₂₃ of ≦ 35 °.

2-2-2. Straight part

The angle θ ₂₂ formed by the straight line R ₂₂ and the base line must be in a range of 25 ° to 35 °. If there are two or more straight lines, at least one angle θ ₂₂ must not satisfy this range. In addition, when angle (theta) ₂₂ exists in this range, the angle of each linear part may differ.

By adjusting the angle θ ₂₂ to these ranges, planes are formed for the entire unit lens and the entire optical sheet, and by the formation of this plane, the luminance in the viewing angle direction in the region immediately above the cold cathode tube of the light source device is adjusted. It is possible to improve, and it is possible to solve the decrease in luminance in the viewing angle direction in the region immediately above the cold cathode tube of the light source device generated by the installation of ordinary lens sheets (prism sheet, lenticular sheet, etc.).

Moreover, also in the setting of the distance between various adjacent cold cathode tubes, or the distance of the optical sheet and cold cathode tube of this invention, in the area | region immediately adjacent to the cold cathode tube of a light source apparatus by adjusting the said angle (theta) ₂₂ setting. It is possible to improve the luminance in the viewing angle direction. Also in the combination of the optical sheet and the other optical sheet of the present invention, by adjusting the setting of the angle θ ₂₂ , it is possible to improve the luminance in the viewing angle direction in the region immediately above the cold cathode tube of the light source device. Done. If the angle θ ₂₂ is not within this range, it is difficult to improve the luminance of the region immediately above the cold cathode tube of the light source device.

2-2-3. Combination of Curves and Straight Lines

The shape of the entire convex portion outer periphery of the second unit lens consists of a combination of the above-described curve and straight line settings. Among these combinations, the top portion of the convex portion outer circumferential line of the second unit lens may be a curved portion (for example, see FIGS. 7 to 9), and a so-called prism shape composed only of a straight portion (for example, FIG. 10). The curved portion and the straight portion may be combined. In addition, the part which contacts a baseline may be either a straight line or a curve.

As an example of the combination of the setting of the curve and the straight line, Fig. 7 shows that three curves of the convex portion including the curve of the top portion in the cross-sectional shape have a single elliptical shape. 8 consists of two curves and one straight line, and these two curves have a single elliptical shape. 9 is an example in which the top portion and the portion in contact with the base line have different elliptical shapes among the curves of the convex portions in the cross-sectional shape. 10 is an example in which the top portion of the cross-sectional convex portion has a prism shape in which two straight lines are combined.

The distribution of the setting of the curve and the straight line is defined by the ratio of the total length (V) of the projection of the curve of the convex peripheral line to the lens baseline and the total (W) of the length of the projection of the straight line to the lens-shaped baseline. . It is preferable that the said ratio (V: W) is 15:85 or more and 85:15 or less. In this range, measurement in the setting should be performed by adjusting the ratio based on various device settings (light source device conditions, combination with an optical sheet other than the present invention) (should exhibit the effect of the present invention). From the light emitting surface side, the light source device can improve the luminance in the viewing angle direction in the intermediate region of the adjacent cold cathode tube, and also improve the luminance in the viewing angle direction in the region immediately above the cold cathode tube. Therefore, high brightness uniformity can be attained as the whole light source device surface.

For example, when the optical sheet of the present invention is used as the first optical sheet and the second optical sheet used in combination is a prism sheet, the ratio of the optimal curve and the straight line can be determined by the vertex angle and the pitch of the prism sheet. . In that case, the ratio (V: W) is preferably 20:80 or more and 80:20 or less, more preferably 30:70 or more and 80:20 or less, and more preferably 40:60 or more and 80:20 or less to be. If the ratio of the curve is smaller than this, it becomes impossible to uniformly diffuse sufficient light in the intermediate region of the cold cathode tube array, and if it becomes larger than this, erasure of the dark lines generated when the prism sheets are superimposed becomes difficult.

2-3. The angle of the tangent of the curve to the baseline

In the vertical cross-sectional shape with respect to the longitudinal direction of the said 1st and 2nd unit lens, when the tangent of the curve on the outer periphery of a convex-shaped part makes the largest of the angle which forms with a baseline is θ _{11 max} and θ _{21 max} , these θ _{11 max} and θ _{21 max} are preferably at least 45 °, more preferably at least 50 °, even more preferably at least 55 °.

On the other hand, when angle (theta) ₁₁ , (theta) ₂₁ becomes 75 degrees or more, in the curve part, incident light from a light source will not be able to be emitted in a substantially front direction by reflection. Therefore, the unit lenses the total of the phase convex portion outer peripheral line of the vertical cross-section, the two curved portions tangent baseline and angle (θ _11, θ ₂₁₎ is projected on the baseline of the portion becomes equal to or greater than 75 ° length, baseline It is preferable that it is 10% or less with respect to a full length, and it is more preferable that it is 5% or less. By adjusting the angles θ ₁₁ and θ ₂₁ in these ranges, it becomes possible for the light source device to improve the luminance in the viewing angle direction in the intermediate region of the adjacent cold cathode tube rows.

Also, in setting the distance between various adjacent cold cathode tube thermal intervals and the distance between the optical sheet and the cold cathode tube of the present invention, by adjusting the settings of two or more θ _{11 max} and θ _{21 max} that satisfy the conditions. It is possible to improve the luminance in the viewing angle direction in the intermediate region of the adjacent cold cathode tube. In addition, by also Similarly, adjusting the two or more θ _{11 max,} set of θ _{21 max} which satisfies the conditions and the combination of the optical sheet and another optical sheet of the present invention, the viewing angle in the intermediate region of the cold-cathode tube that neighbors Since the luminance in the direction can be improved, the luminance variation can be reduced as a whole of the optical sheet.

2-4. Ratio of height (H) to width (P)

In the first or second unit lens, the ratio (H / P) of the length P of the base line in the vertical cross-sectional shape with respect to the longitudinal direction of the unit lens and the height H from the base line to the lens apex is special. Although not limited, it is preferable that they are 0.25 or more and 0.75 or less, and 0.3 or more and 0.6 or less are more preferable. In the first unit lens, when the ratio H / P is less than the above range, the ratio of the configuration of the curved portion R ₁₁ to the curved portion R ₁₂ is decreased, and in the intermediate region of the adjacent cold cathode tube, It becomes difficult to diffuse light sufficiently, and the luminance in the viewing angle direction in this region cannot be improved. On the other hand, the optical sheet of the diffusion sheet and the ratio is reduced, with a prism sheet or a lens for the ratio (H / P) curved portion (R ₁₁₎ in this case beyond the above range, the curved portion (R ₁₂₎ In the case of superimposing, the luminance of the cold cathode tubular region becomes insufficient, and it is difficult to eliminate the luminance deviation. In the second unit lens, if the ratio (H / P) is less than the above range, the effect of the lens becomes small, and it becomes difficult to diffuse light sufficiently into the intermediate region of the adjacent cold cathode tube. It is not possible to improve the luminance in the viewing angle direction. On the other hand, when the ratio (H / P) exceeds the above range, the light is diffused to the portion beyond the intermediate region of the neighboring cold cathode tube, so that the luminance uniformity in the intermediate region is lowered. In the viewing angle direction, the luminance uniformity decreases. In addition, although the length P and height H of a unit lens can be set suitably according to desired characteristic, length P is usually 10 micrometers or more and 300 micrometers or less, and height H is 2.5 micrometers or more 225 탆 or less.

2-5. Combination of module lens structure

The first or second unit lens structure is an optimal shape to achieve high brightness uniformity. Thus, in general, other unit lens structures may be added. In order to exhibit desirable performance as the whole optical sheet, it is preferable that at least 50 area% of the entire light exit surface of the optical sheet is composed of the first unit lens and / or the second unit lens, and more preferably 60 area% or more. , 70 area% or more is more preferable, and 90 area% or more is more preferable. As a lens structure different from the above, a lenticular shape and a prism shape are mentioned, for example. In the unit lens structure of these optical sheets, the first or second unit lens structure may be a combination of the same or a combination of a plurality of types of structures. Moreover, it is also a preferable aspect that the said lens group is comprised only by the said 1st or 2nd unit lens.

3. Third embodiment

In order to explain 3rd Embodiment, it demonstrates using the perpendicular | vertical cross section (shape of a vertical cross section) with respect to the linear ridge direction (the longitudinal direction of a lens) of the lens arrange | positioned in linear ridge shape on an optical sheet (refer FIG. 11). ). In the optical sheet according to the third embodiment of the present invention, the lens group is a convex portion outer periphery of a vertical cross-sectional shape with respect to the longitudinal direction, and has a unit lens having the following shape 1 (see FIG. 12) and a unit lens having shape 2. (See Fig. 13).

Thus, by arranging at least two different unit lenses almost in parallel, the surface shape as the whole lens molding surface of the optical sheet is constituted. The arrangement of the other two kinds of unit lenses may be arranged randomly without regularity, or may be arranged with constant regularity.

3-1. Shape 1

The shape 1 has an outer circumference formed by a curved line or a straight line, and an angle θ ₃₂ formed between a tangent line or a straight line at all points on the curve and a base line of the unit lens cross-sectional shape is 25 ° ≤θ ₃₂ ≤35 ° the part (R ₃₂₎ includes, the total number (r ₃₂₎ of the unit lens is a projection length of the baseline of the cross-sectional shape of the part (R ₃₂₎ for a baseline full length of the unit lens cross-sectional shape is at least 90% .

Shape 1 includes a portion R ₃₂ at which the angle (θ ₃₂ ) between the tangent or straight line and the base line at every point on the curve becomes 25 ° ≦ θ ₃₂ ≦ 35 °, but at the baseline of R ₃₂ The ratio of the total length r ₃₂ of the projected length to the baseline electric field is 90% or more. When the ratio of the total r ₃₂ is less than 90%, the luminance of the cold cathode tube region is superimposed when the optical sheets such as a prism sheet or a diffusion sheet having a lens can be generally used to increase the luminance in the viewing angle direction. Is lowered and it is difficult to eliminate the luminance deviation. The ratio of the total amount r ₃₂ is more preferably 95% or more, and more preferably 100%. In addition, the part R ₃₂ which occupies 90% or more of the said shape 1 consists of a straight line or a curve, and may be a combination of several straight line and a curve. For example, what is called a prism shape which consists of two straight lines is one of the preferable forms of this invention. Moreover, when a curve is included, it is preferable that it is a part of a secondary curve from a viewpoint of the ease of design, workability, and optical performance, and it is still more preferable that it is a part of hyperbolic. In addition, although the shape 1 may be asymmetrical in shape, it is preferable to be symmetrical in order to reduce the difference in luminance deviation due to the viewing angle.

3-2. Shape 2

In the shape 2, the total length r ₃₃ of the outer circumferential line mainly composed of the curved portion, and the total length r ₃₃ projected on the base line of the unit lens shape of the portion R ₃₃ represented by a single quadratic curve is the unit lens shape. Curved portion R ₃₁ , which is 90% or more with respect to the baseline electric field, and whose angle (θ ₃₁ ) between the tangent and baseline at all points on the curve is θ ₃₁ ≧ 40 ° as part of the portion R _33. ), And the ratio of the total length r ₃₁ of the length R ₃₁ projected to the base line of the lens cross-sectional shape of the portion R ₃₁ is 20% or more.

The shape 2 has a portion R ₃₃ represented by a single quadratic curve, but the quadratic curve is preferably part of an ellipse or a hyperbola. In the case where the portion R ₃₃ is part of an ellipse, the eccentricity ratio is preferably 0.50 or more and 0.95 or less, more preferably 0.70 or more and 0.93 or less, and still more preferably 0.80 or more and 0.90 or less. Further, the shape 2 includes a curved portion R ₃₁ whose angle θ ₃₁ between the tangent line and the base line at all points on the curve is θ ₃₁ ≧ 40 °, but this curved portion R ₃₁ The ratio of the total length (r ₃₁ ) of the length projected on the baseline to the baseline electric field is 20% or more. When the ratio of the total r ₃₁ is less than 20%, light diffusion to the middle portion of the cold cathode tube row decreases, and the luminance in the viewing angle direction in the middle portion is lowered, making it difficult to eliminate the luminance deviation. In addition, although the shape 2 may be asymmetrical in shape, it is preferable that the shape 2 is symmetric in order to reduce the difference in luminance deviation due to the viewing angle.

In addition, the shape 2 is normal, the portion as a part of the (R _33), the baseline and the tangent angle (θ ₃₄₎ is 25 ° ≤θ ₃₄ ≤ 35 ° the part of the all points on the curve (R ₃₄ Also has.

3-3. Combination of Shape 1 and Shape 2

The shape 1 and the shape 2 as the vertical cross-sectional shape with respect to the longitudinal direction of the unit lens in the optical sheet of the third embodiment do not need to be a single shape as long as they satisfy the above conditions. There may be a plurality of types of shapes satisfying the above conditions.

The unit lens having the shape 1 and the unit lens having the shape 2 are area ratios of the unit lens having the shape 1 and the unit lens having the shape 2 (shape 1 / It is preferable to arrange | position so that shape 2) may be 0.05 or more and 2.0 or less. When the area ratio is less than 0.05, in order to increase the luminance in the viewing angle direction, when an optical sheet such as a prism sheet or a diffusion sheet having a lens, which can be used in general, is superimposed, the luminance of the cold cathode tube region is lowered, so that There is a fear that resolution will be difficult. On the other hand, when the area ratio exceeds 2.0, the light diffusion to the middle portion of the cold cathode tube row decreases, and the luminance in the viewing angle direction in the middle portion decreases, making it difficult to eliminate the luminance deviation. The area ratio is more preferably 0.1 or more and 1.5 or less, more preferably 0.15 or more and 1.0 or less, and most preferably 0.2 or more and 0.75 or less.

Moreover, as arrangement | positioning of the shape 1 and the shape 2, it is preferable to set it as 20 or less, and to set it as 10 or less which mutually neighbors the lens which belongs to the shape 1 and the shape 2, respectively, satisfying the said area ratio. desirable. If the lenses belonging to the shape 1 and the shape 2 are adjacent to each other more than the above range, the uniformity of the optical performance as the whole optical sheet is impaired, and there is a possibility that the luminance uniformity is insufficient. For luminance equalization, it is preferable that the area ratio (shape 1 / shape 2) is satisfied and arranged almost uniformly as a whole. From the viewpoint of model creation, the repetition of the same arrangement pattern is easy to manufacture, and the uniformity of the whole optical sheet is also easy to design, and is most preferable.

3-4. Ratio of height (H) to width (P)

The length P of the baseline of the convex portion outer peripheral line in the vertical cross-sectional shape with respect to the longitudinal direction of the unit lens is the length L1 of the baseline of the unit lens having shape 1 and the length of the baseline of the unit lens having shape 2 ( It is preferable that all of L2) are 30 micrometers or more and 300 micrometers or less, 40 micrometers or more and 200 micrometers or less are more preferable, and 50 micrometers or more and 150 micrometers or less are more preferable. When the length P exceeds the said range, the luminance uniformity in a viewing angle direction will fall, or there exists a tendency for a moire pattern to become easy to generate | occur | produce according to the combination with the optical sheet to superimpose. On the other hand, when the length P is less than the above range, when the lens sheet is transferred and manufactured by using a model in which the optical sheet of the third embodiment is aligned with the lens shape, the lens sheet is transferred after the lens shape transfer. There exists a possibility that a mold release may become difficult.

Further, the height H from the baseline of the convex portion outer peripheral line in the vertical cross-sectional shape with respect to the longitudinal direction of the unit lens to the lens apex is the height H1 of the unit lens having the shape 1 and the unit lens having the shape 2. As for height H2, 15 micrometers or more and 100 micrometers or less are preferable, 20 micrometers or more and 85 micrometers or more are more preferable, and 25 micrometers or more and 65 micrometers or less are more preferable. When the height H exceeds the above range, when the optical sheet of the third embodiment is transferred and manufactured by using a model that is amenable to the lens shape, there is a possibility that the release after the lens shape transfer becomes difficult. . On the other hand, when height H is less than the said range, the light-diffusion effect of a lens may become small and brightness uniformity may fall.

Although the ratio H / P of the height H and the length P is not particularly limited, the unit lens having the shape 1 preferably has a ratio H1 / L1 of 0.20 or more and 0.40 or less, and 0.22 or more. 0.35 or less are more preferable. On the other hand, as the unit lens having the shape 2, the ratio (H2 / L2) is preferably 0.25 or more and 0.75 or less, and more preferably 0.30 or more and 0.65 or less. If the ratio (H / P) is less than the above range, the light diffusion effect of the lens becomes small, and there is a fear that the brightness uniformity is lowered. On the other hand, when the ratio (H / P) exceeds the above range, the light diffused from the unit lens is incident on the neighboring unit lens again, so that the light is not emitted toward the front panel direction, and the luminance is lowered. There is concern.

3-5. Combination of module lens structure

In the optical sheet of the third embodiment, the unit lens having the shape 1 and the unit lens having the shape 2 are optimal shapes and combinations in order to achieve high brightness uniformity. Therefore, other unit lens structures may normally be included. In order to exhibit the preferable performance as the whole optical sheet, it is preferable that 80 area% or more of the whole light exit surface of an optical sheet consists of the unit lens which has the said shape 1, and the unit lens which has the said shape 2, and is 90 area% or more The structure is more preferable, and the composition of 95 area% or more is more preferable. The other unit lens structure may be a combination of the same or a combination of a plurality of.

4. Arrangement of the unit lens on the optical sheet plane

In the optical sheet of the present invention, in the vertical section with respect to the longitudinal direction of the unit lens, the interval between the top portions of the outer peripheral lines of the convex portions of neighboring unit lenses is preferably 300 µm or less. When the said space | interval exceeds 300 micrometers, the brightness uniformity in a viewing angle direction will fall, or a moire pattern will become easy to generate | occur | produce according to the combination with the optical sheet to superimpose. The arrangement of the lens groups arranged in such a straight ridge shape may be the above-mentioned placement ratio as the whole optical sheet. For example, the said 1st or 2nd unit lens or the unit lens which has the shape 1, and the unit lens which has the shape 2 may be lined up at the said space | interval, and another unit lens (for example, a lenticular shape or a prism shape) May neighbor.

In the optical sheet of the present invention, the configuration of the connection portion between neighboring unit lenses is not particularly limited as long as it does not affect the intended optical performance. For example, in the case where only the optical performance as designed by the unit lens is to be achieved in the entire optical sheet, ideally, all of the lowest portions of the outer periphery of the convex portion in the vertical section with respect to the longitudinal direction of the unit lens are It is desirable to be unitary, that is, to arrange unit lenses without gaps.

However, as long as it does not affect the optical performance as the whole optical sheet, a gap can be formed between each unit lens. For example, in the step of transferring the lens shape of the optical sheet of the present invention, this provides a slight gap so as to facilitate release after lens shape transfer. With respect to the cross-sectional shape between the unit lenses given to the optical sheet of the present invention by this slight gap, any shape such as a straight line, a concave curve, a V-shape, or the like may be used. It is the same as that.

On the contrary, in order to supplement, enhance, or supplement other optical performances of the unit lenses having a specific shape defined in the present invention, the lowest portions of neighboring unit lenses are separated from each other, It is possible to add a shape such as to express an effect according to this.

5. Structure of Optical Sheet of the Present Invention

5-1. Transparent Thermoplastic

The thermoplastic resin constituting the optical sheet of the present invention is not particularly limited as long as it is transparent and has a suitable strength as a component that is the center of the optical sheet. Polycarbonate resins; Acrylic resins such as polymethyl methacrylate; Styrene resins such as polystyrene, polyvinyl toluene and poly (p-methylstyrene); MS resin (copolymer of methyl methacrylate and styrene); Polyolefin resins such as norbornene-based resins; Polyarylate resins; Polyethersulfone resin Two or more types of these mixed resin etc. can be used. Suitably, polycarbonate resin, styrene resin or norbornene resin is used. Especially, since polycarbonate resin is excellent in transparency, heat resistance, and workability, and its balance is good, it is especially preferable as resin for optical sheets. The thermoplastic resin may contain a ultraviolet absorber, a fluorescent brightener, a flame retardant, or the like as necessary.

5-2. Light diffusion layer

The optical sheet of the present invention may be composed of only transparent resin, but in order to adjust the light diffusivity, a light diffusing layer made of particles having light diffusing ability may be formed. The light diffusing layer can be uniformly or randomly dispersed in the entire optical sheet, only the lens portion, all other than the lens portion, only the light-emitting surface surface layer, only the light-emitting surface surface layer, or the intermediate layer. In the light diffusion layer, light diffusing particles (light diffusing agent) having a refractive index difference of 0.01 or more from the transparent resin are dispersed in the thermoplastic resin, and have an effect of adjusting the diffusion direction and the diffusion ratio of light diffusion by the lens. This makes it possible to further increase the luminance uniformity in the viewing angle direction. Here, when the number of optical sheets to be used for the light source device is reduced, a problem may arise that an image of a pin supporting the optical sheet appears in the backlight unit. However, in the optical sheet of the present invention, by providing the light diffusing layer, the support pin image can be erased even when the number of used sheets is reduced.

5-3. Light diffuser

As a material of light diffusing particle | grains (particulates), For example, synthetic resins, such as (meth) acrylic-type resin, a styrene resin, a polyurethane-type resin, polyester-based resin, a silicone type resin, a fluorine-type resin, these copolymers; Glass; Clay compounds such as smectite and kaolinite; Inorganic oxides such as silica and alumina; Etc. can be mentioned. Among these materials, (meth) acrylic resins, silicone resins and silicas are particularly suitable. The light diffusing agent may use any of a single material of these exemplary materials, a mixture of single materials, a mixed material, and a mixture of mixed materials. In addition, in this application, a (meth) acryl means an acryl and / or methacryl.

The average particle diameter of the light diffusing particles is preferably 0.1 µm or more and 50 µm or less, more preferably 0.3 µm or more and 10 µm or less, further preferably 0.5 µm or more and 5 µm or less. If the particle diameter of the light diffusing particles is out of the above range, there is a fear that sufficient light diffusivity cannot be exhibited. Here, the average particle diameter of the light diffusing particles is a volume-based median diameter measured by a particle size distribution measuring device (coulter counter).

Although the ratio of a thermoplastic resin and light-diffusing particle can be adjusted suitably, For example, 0.01 mass part or more and about 10 mass part or less may be added to 100 mass parts of thermoplastic resins. When light diffusing particle | grains are less than 0.01 mass part, adjustment of the brightness uniformity by a light-diffusion agent will not be enough. On the other hand, when the light diffusing particles are more than 10 parts by mass, the transparency of the light diffusing layer may be lowered, which may lower the brightness of the entire optical sheet.

In the optical sheet of the present invention, when it is necessary to further increase the anisotropic light diffusing performance as the optical performance, a low-crosslink density organic fine particle capable of expressing the anisotropic light diffusing property at the time of molding the optical sheet is preferably used. As raw material monomers of the low-molecular density organic fine particles, (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, n-butyl (Meth) acrylate, iso-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, hydrate (Meth) acrylates, such as oxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate; Styrenes such as styrene, p-methylstyrene, vinyltoluene and p-t-butyl styrene; Maleimides such as N-phenylmaleimide, N-cyclohexyl maleimide, and N-benzyl maleimide; (Meth) acrylamides, such as (meth) acrylamide and N-methylol (meth) acrylamide; Acrylonitriles such as (meth) acrylonitrile; N-vinylpyrrolidone; 1 type or 2 or more types of these can be mixed and used.

As a crosslinking agent of low-density crosslinked organic fine particles, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tree Polyfunctional (meth) acrylates such as (meth) acrylate and bishydroxyethylbisphenol Adi (meth) acrylate; Radical polymerizable crosslinking agents such as divinyloxyethoxy (meth) acrylate, diallyl phthalate, allyl (meth) acrylate, and divinylbenzene; Polyfunctional epoxy compounds such as bisphenol A diglycidyl ether, diethylene glycol diglycidyl ether and neopentyl glycol diglycidyl ether; Polyfunctional isocyanate compounds such as tolylenedisocyanate, xylylenedisocyanate and isophoronedisocyanate; 1 type of polyfunctional methylol compounds, such as N-methylol melamine and N-methylol benzoguanamine; or 2 or more types of these can be mixed and used.

The low-crosslink density organic fine particles for producing anisotropic light diffusing performance have a crosslinking density of 0.001% or more and 0.12% or less. Such low-molecular density organic fine particles are spherical or almost spherical in the raw material stage, but due to the heat and shearing force received during the molding of the optical sheet, ellipsoidal or rod-shaped shapes are formed at predetermined positions (layers, etc.) of the optical sheet. Anisotropic diffusivity is expressed by changing into a shape. In addition, a crosslinking density is a numerical value calculated by following formula (1).

Fn (c): number of functional groups of the crosslinking agent used in the production of radical polymer-based crosslinked fine particles

Mw (c): Molecular weight of the crosslinking agent used for the production of radical polymer-based crosslinked fine particles

W (c): Mass blending ratio (%) of the crosslinking agent used for the production of radical polymer-based crosslinked fine particles

W (m): Mass mix ratio (%) of monomers used for producing radical polymer-based crosslinked fine particles

Provided that Fn (c) ≥2, W (m) + W (c) = 100

5-4. Antioxidant

An antioxidant can be further mix | blended with the organic fine particle containing the low molecular weight organic fine particle of this invention, or at least one of a thermoplastic resin. Since antioxidant can suppress coloring of the thermoplastic resin and organic fine particles by oxidation and deterioration at the time of heat shaping | molding, the brightness | luminance of the backlight apparatus which applied the optical sheet of this invention can be exhibited more reliably.

As said antioxidant, a conventionally well-known thing can be used. For example, pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-1 Hindered phenol antioxidants such as -hydroxyphenyl) propionate; Tris (2,4-di-t-butylphenyl) phosphite, tris [2-[[2,4,8,10-tetra-t-butyldibenzo [d, f] [1,3,2] di Phosphorus antioxidants such as oxa phosphine-6-yl] oxy] ethyl] amine; Pentaerythryl tetrakis (3) having an aromatic ring and having no aromatic ring, such as thiodiethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] Sulfur-based antioxidants such as lauryl thiopropionate); Lactone-based antioxidants such as reaction products of 3-hydroxy-5,7-di-t-butyl-furan-2-one and o-xylene; Hydroxylamine antioxidants such as oxidation products of alkylamines using reduced type tallow; Vitamin E antioxidants such as 3,4-dihydro-2,5,7,8-tetramethyl-2- (4,8,12-trimethyltridecyl) -2H-benzopyran-6-ol and the like can be used. Can be.

Although the usage-amount of antioxidant can be adjusted suitably, 0.005 mass% or more and 0.3 mass% or less may be added normally with respect to a thermoplastic resin. That is, it is good to add about 0.005 mass parts or more and about 0.3 mass parts or less of antioxidant with respect to 100 mass parts of thermoplastic resins.

Although the thickness of the optical sheet of this invention can be suitably adjusted and it does not restrict | limit especially, Usually, it can be about 0.3 mm or more and about 10 mm or less. If the thickness of the optical sheet is less than 0.3 mm, the light diffusing action may not be sufficiently exhibited, or the rigidity may be insufficient to maintain shape stability. On the other hand, if the thickness of the optical sheet exceeds 10 mm, the entire apparatus to which the optical sheet of the present invention is applied may not be compact. The thickness of the optical sheet is more preferably 0.5 mm or more and 5 mm or less. In addition, the thickness of an optical sheet is a sum of the thickness of a base part and a unit lens height (refer FIG. 4, FIG. 5, FIG. 11).

6. Manufacturing method of optical sheet

The optical sheet of the present invention can be manufactured by using a model that is strict in a predetermined surface shape. The shape of the model may be a structure in which the lens group of the optical sheet obtained is a shape for realizing a predetermined surface shape defined in the present invention, that is, convex portions of these surface shapes are concave and concave portions are convex. have. In the present invention, the models of these structures are referred to as "strict models for forming a surface shape" (see Figs. 14 and 15).

The optical sheet of this invention can be manufactured by the manufacturing process which has the said model. Specifically, a transparent thermoplastic resin or a compound in which fine particles having light diffusivity are blended with the transparent thermoplastic resin can be used, and known extrusion molding or injection molding can be used. In order to adjust the optical performance or other physical properties of the laminate (for example, when the light diffusion layer is provided only on a specific layer such as the light incident side or the lens side, or the UV absorber compounding layer for improving the light resistance of the optical sheet, or electrostatic In the case of providing an antistatic layer for preventing dust from adhering to the optical sheet), a method by extrusion molding is particularly preferable in terms of productivity. Moreover, especially when molding a lens shape with a narrow pitch, it is especially preferable to use the method of Unexamined-Japanese-Patent No. 2008-249254.

Whether or not the molded product as designed in the present invention is manufactured can be confirmed by calculating x ₁ and x ₂ from the molded product. Specifically, the vertical cross-sectional shape of the unit lens in the longitudinal direction is photographed by an electron microscope or the like, and in the outer periphery of the convex portion, the curve is appropriate for the curve (multiple combinations may be used). Is calculated from the range of the outer circumference line where the angle formed by the tangent line with the base line becomes the predetermined angle, and from the range of the outer circumference line where the angle of the straight line base line becomes the predetermined angle.

7. Combination with other optical sheets

It is preferable to use the optical sheet of this invention as a 1st optical sheet in order to use the high optical performance adjustment ability efficiently in another optical sheet and apparatus setting. By using it as a 1st optical sheet, the light source device improves the brightness | luminance in the viewing angle direction in the intermediate region of the adjacent cold cathode tube, and the brightness | luminance in the viewing angle direction in the area | region immediately adjacent to a cold cathode tube is improved. You can take full advantage of the effect you have. In addition, when used as the first optical sheet, a prism sheet, a diffusion sheet, a micro lens sheet, or the like can be used as another optical sheet, and a suitable combination can be selected depending on the conditions of the light source device. It is preferable to use a diffusion sheet as the optical sheet closest to the panel. Above all, the use of at least one prism sheet for the second and subsequent optical sheets further eliminates dark lines generated in the vicinity of the cold cathode tube, thereby realizing luminance uniformity at high luminance on the light exit surface immediately before the front panel. It becomes possible.

Moreover, in order to reduce repeated cost, it is desired to reduce the number of optical sheets used for a light source device. Here, when the number of sheets of use of the optical sheet is reduced, not only the luminance deviation is more difficult to be solved, but also a problem occurs that an image of the pin supporting the optical sheet appears in the backlight unit. That is, in the conventional optical sheet, since a large number of (four or more) optical sheet groups are required to erase the pattern of the linear light source, the image of the support pin is also erased by the action of these optical sheets, thereby supporting The pin image has never been a problem. In the conventional optical sheet, when the number of sheets used was reduced to three sheets, the support pin image could not be recognized because the pattern of the line light source could not be erased.

However, in the optical sheet of the present invention, in order to express excellent light diffusing performance by using in combination with the prism sheet, the pattern of the line light source can be erased even if the number of sheets of the optical sheet is reduced to three. Thus, by using the optical sheet of the present invention and reducing the number of sheets to three, it has been found that the image of the support pin is sharply noticeable for the first time. Here, when the optical sheet of the present invention has a light diffusing layer, the performance of erasing the image of the support pin for supporting the optical sheet in the direct type light source device is also improved. Therefore, when the optical sheet of this invention has a light-diffusion layer, it is also a preferable aspect to use only three sheets of the optical sheet, prism sheet, and light-diffusion sheet of this invention.

Since the optical sheet manufactured by the present invention can diffuse light in a desired direction and consequently maintain light uniformity, it is possible to exhibit high brightness while reducing the manufacturing cost of a liquid crystal display device which is increasing in demand. Very useful. Therefore, the manufacturing cost can be reduced by applying the optical sheet of this invention and the direct type light source apparatus which has this optical sheet to a liquid crystal display device etc.

Example

Next, although the Example as an Example of this invention is demonstrated to Tables 1-6, this invention is not limited to this example.

1. Manufacturing of optical sheet

An optical sheet in which polycarbonate is used as a raw material, and an embossing process (arithmetic mean roughness Ra = 2 to 6 µm) on a light incident surface and a linear ridge lens group having various types of cross-sectional shapes are arranged on the light incident surface by extrusion molding. Prepared.

2. Surface measurement of optical sheet

The cross-sectional shape of the produced various optical sheets was confirmed using a scanning electron microscope. The observation result of surface shape is shown to Tables 1-3.

3. Luminance deviation evaluation

In the test, a white reflector was provided on the inner surface of a plastic case having an inner width of 690 mm, a depth of 390 mm, and a depth of 10 mm, and 19 cold cathode tubes having a diameter of 3 mm were placed in parallel at 20.5 mm intervals at a position 3.5 mm from the bottom of the reflector. The direct type light source device arranged was used. On the direct type light source device, the optical sheet of the present invention in various shapes was disposed so that the lens processing surface was on the top, and the longitudinal direction of the lens was parallel to the longitudinal direction of the cold cathode tube. On this optical sheet, a commercially available light diffusing sheet (Akseo Photoelectric (Suzhou) Co., Ltd., CH273), a prism sheet (Sumitomos Leem, BEF II 90/50: vertex angle of 90 degrees, pitch of 50 µm), microlens sheet (Astronaut Photoelectric (Suzhou) Co., Ltd., ML24M: an optical sheet in which hemispherical convex lens groups are finely arranged on one surface) were laminated according to the combinations of Table 4. In each combination, luminance deviation was visually observed at a position 400 mm in the vertical direction from the center of the direct type light source device. The luminance deviation is evaluated in 10 steps, and the larger the value is, the smaller the luminance variation is, and it is indicated that the lamp image of the cold cathode tube becomes inconspicuous. The evaluation results are shown in Tables 1-3.

 Display Direction ← → Backlight Direction Pattern A  Diffusion sheet / prism sheet / diffusion sheet Pattern B  Micro Lance Sheet / Prism Sheet / Diffusion Sheet Pattern C  Diffusion Sheet / Prism Sheet / Micro Lens Sheet

For the optical sheets described in Tables 1 to 3, the length (x ₁ ), the length (x ₂ ), and the total (x _1total ) and the total (x _2total ) of each unit lens constituting the lens group were measured. It summarized in Table 5.

The total (x _1total) that is 25% to 60% of the total amount (P _total) of the baseline length of the lens group, also, the total number (x _2Total) of 25 of the total (P _total) of the baseline length of the lens When Examples 1 to 35 which are% to 60% are used, the luminance variation is small in any combination shown in Table 4.

4. Support pin image, luminance deviation evaluation

In the test, a white reflective plate was provided on the inner surface of a plastic case having an inner width of 690 mm, a depth of 390 mm, and a depth of 25 mm, and eight cold cathode tubes having a diameter of 3 mm were arranged in parallel at a distance of 45 mm at a position 5 mm from the bottom of the reflecting plate. 30, the direct type light source device which arrange | positioned the support pin was used. On the direct type light source device, the optical sheet of the present invention in various shapes was disposed so that the lens processing surface would be on top, and the longitudinal direction of the lens would be parallel to the longitudinal direction of the cold cathode tube. On this optical sheet, a prism sheet (Sumitomos Lee M Co., BEF II 90/50: a vertex angle of 90 degrees, a pitch of 50 µm) was laminated, and a microlens sheet (Auckoo Photoelectric (Suzhou) Co., Ltd., ML24M) on one side thereof. The optical sheet in which the hemispherical convex lens group was arrange | positioned finely was laminated | stacked on the surface. In each optical sheet group, the support pin image and brightness deviation were visually observed at a position 400 mm away from the center of the direct light source device. The support pin image was said to be "bad" when visually confirmed, "good" that could be partially confirmed, and "very good" that could not be confirmed at all. The luminance deviation is evaluated in 10 steps, and the larger the value, the smaller the luminance deviation is, and the less the image of the lamp of the cold cathode tube is inconspicuous. The evaluation results are shown in Table 6.

Optical sheet of the present invention evaluation Kinds
Diffuser
Support Pin Image
Luminance deviation Addition amount ^{* 1} Average particle size
(Μm) Location Example 13 0.5 4 Uniform throughout Right 8 Example 12 0 - - Bad 7 Example 1 0 - - Bad 8 Comparative Example 1 0 - - Bad 3 Comparative Example 2 0.5 4 Uniform throughout Right 2

* 1 The amount of diffusion agent added is% by mass relative to the thermoplastic resin

Example 13 is an optical sheet in which the total amount (x _1Total ) and the total amount (x _2Total ) are within the prescribed range of the present invention and are provided with a light diffusion layer. When the optical sheet of Example 13 is used, the support pin image can be erased by the three optical sheet groups, and the luminance deviation is small.

(Industrial availability)

By using the aspect of this invention, the 1st optical sheet which can improve the brightness ratio in the intermediate point between the line light sources installed next to each other, and / or directly above (right above) a cold cathode tube, and can obtain a uniform brightness distribution, It is very useful in industry because it can provide a direct type light source device and a liquid crystal display device.

1: cold cathode lamp
2: reflective film
3: first optical sheet
4: second optical sheet
5: third optical sheet
6: 4th optical sheet
7: front panel

Claims (21)

An optical sheet having a convex lens group formed on a surface in a straight ridge shape,
The outer periphery of the convex portion of all the lenses in the vertical cross-sectional shape with respect to the longitudinal direction of the lens group is constituted by curves and / or straight lines,
A part X ₁ whose angle θ between the tangent line and / or the straight line and the base line at all points on the curve is θ ≧ 40 °, and
A portion X ₂ having an angle θ formed between a tangent line and / or the straight line and the base line at all points on the curve, wherein 25 ° ≦ θ ≦ 35 °,
The total amount x _1total of the length x ₁ projected onto the baseline of the lens group of the portion X ₁ is 25% or more and 60% or less of the _total P length of the baseline length of the lens group. A total (x _2total ) of the length (x ₂ ) projected on the baseline of the lens group of the part (X ₂ ) is 25% or more and 60% or less of the total (P _total ) of the baseline length of the lens group. Optical sheet. The method of claim 1, wherein the lens group,
The outer periphery of the convex portion in the vertical cross-sectional shape with respect to the longitudinal direction of the unit lens mainly consists of a curve, and the angle (θ ₁₁ ) between the tangent and the base line at all points on the curve is θ ₁₁ ≥40 °. which comprises a curved portion (R ₁₁₎ and a tangent and the angle (θ ₁₂₎ forming the baseline of 25 ° ≤θ ₁₂ ≤35 ° curved section ₍₁₂ R) in all points on the curve,
The ratio of the total length r ₁₁ of the length of the curved portion R ₁₁ projected to the base line of the unit lens shape of the curved portion R _{11 to} the full length of the base line is 25% or more and 60% or less, and the curved portion R ₁₂ . And a first unit lens having a ratio of the total length (r ₁₂ ) of the total length (r ₁₂ ) projected to the base line of the unit lens shape of the base lens of the unit lens of 25% to 60%. The optical sheet according to claim 2, wherein the first unit lens contains two curved portions (R ₁₁ ) and two curved portions (R ₁₂ ). The optical sheet according to claim 2 or 3, wherein the curved portion (R ₁₁ ) is part of a quadratic curve. The method of claim 1, wherein the lens group,
The outer periphery of the convex portion in the vertical cross-sectional shape with respect to the longitudinal direction of the unit lens consists of a shape in which two or more curves and one or more straight lines are connected, and at least two of the curves are formed at every point on the curve. tangential angle and forms the baseline in (θ ₂₁₎ is ≥40 ° θ ₂₁ is comprises a curved portion (R _21), and the angle (θ ₂₂₎ that the straight line (R ₂₂₎ and forms the baseline 25 ° ≤θ ₂₂ An optical sheet having a second unit lens of ≦ 35 °. The method of claim 5, wherein the second unit lens is characterized in that the convex portion outer periphery in the vertical cross-sectional shape in the longitudinal direction of the unit lens has a shape in which two or more curves and two or more straight lines are connected. Optical sheet. The optical sheet according to claim 5 or 6, wherein at least two of the curves are part of a quadratic curve. 8. The second unit lens according to any one of claims 5 to 7, wherein the second unit lens projects a total (V) of a length of projecting the curve on the base line of the unit lens shape, and a straight line on the base line of the unit lens shape. An optical sheet, characterized in that the ratio (V: W) of the total length W is 15:85 or more and 85:15 or less. The ratio of the length P of the base line in the vertical cross-sectional shape with respect to the longitudinal direction of the first or second unit lens, and the height H from the base line to the lens top portion. H / P) is 0.25 or more and 0.75 or less optical sheet. The optical sheet according to any one of claims 2 to 9, wherein the total area of the base portions of the first or second unit lenses is 50 area% or more of the entire light exit surface. The optical sheet according to any one of claims 2 to 10, wherein the lens group includes only the first or second unit lenses. The optical sheet according to claim 1, wherein the lens group includes a unit lens having a shape 1 and a unit lens having a shape 2 as outer periphery of the convex portion having a vertical cross-sectional shape with respect to the longitudinal direction.
`` Shape 1 ''
The portion whose outer circumference is composed of a curved line or a straight line, and the angle (θ <sub>32</sub> ) formed by the tangent line or straight line at all points on the curve and the base line of the unit lens cross-sectional shape is 25 ° ≦ θ <sub>32</sub> ≦ 35 ° ( R <sub>32</sub> ), and the total length r <sub>32</sub> of the portion R <sub>32</sub> projected on the base line of the unit lens cross-sectional shape is 90% or more with respect to the base line length of the unit lens cross-section. .
`` Shape 2 ''
The outer periphery is composed of a curved portion in the main body, and the sum total of the length (r ₃₃ ) projected to the baseline of the unit lens shape of the portion R ₃₃ represented by a single quadratic curve is based on the baseline overall length of the unit lens shape. It is at least 90%, and also including a θ ₃₁ ≥40 ° the curved portion (R ₃₁₎ the angle (θ ₃₁₎ forming tangents to the baseline in all points on a portion of the part (R _33), the curve And a ratio of the total length r ₃₁ of the length projected onto the base line of the lens cross-section of the curved portion R _{31 to} the base line total length is 20% or more. The optical sheet according to claim 12, wherein the sum of the area of the baseline of the unit lens having the shape 1 and the unit lens having the shape 2 is 80 area% or more of the entire light exit surface. The area ratio (shape 1 / shape 2) of the unit lens having the shape 1 and the unit lens having the shape 2 is 0.05 or more and 2.0 or less according to claim 12 or 13 as the sum of the respective projection areas of the entire light emitting surface. An optical sheet characterized by. The length L1 of the base line in the vertical cross-sectional shape with respect to the longitudinal direction of the unit lens having the shape 1, and the height H1 from the base line to the lens vertex according to any one of claims 12 to 14. The ratio H1 / L1 is 0.20 or more and 0.40 or less, and the ratio of the length L2 of the baseline in the vertical cross-sectional shape with respect to the longitudinal direction of the unit lens having the shape 2 and the height H2 from the baseline to the lens apex (H2 / L2) is 0.25 or more and 0.75 or less optical sheet. The lens group according to any one of claims 1 to 15, wherein
An optical sheet according to the vertical section of the lens group in the longitudinal direction, wherein the interval between the top of the outer periphery of the convex portion of the unit lens and the top of the outer periphery of the convex portion of the neighboring unit lens is 300 µm or less. The material constituting the optical sheet according to any one of claims 1 to 16, wherein the material constituting the optical sheet contains a transparent thermoplastic resin, fine particles having a mean particle size different from that of the thermoplastic resin and a refractive index of 0.1 µm or more and 50 µm or less,
The compounding quantity of the said microparticles | fine-particles is 0.01 mass part or more and 10 mass parts or less with respect to 100 mass parts of said thermoplastic resins. The manufacturing method of the optical sheet characterized by using the model which face | fronts in order to form the surface shape of the optical sheet of Claims 1-17. The optical sheet and prism sheet as described in any one of Claims 1-18 are essential. The light source device for display apparatuses characterized by the above-mentioned. A direct type light source device having a plurality of linear light sources, a plurality of support pins disposed between the linear light sources, and a group of three optical sheets placed on the support pins.
A direct type light source device for a display device, wherein the optical sheet group includes only the optical sheet, prism sheet, and light diffusion sheet according to claim 17. A display device comprising the light source device for a display device according to claim 19 or 20.

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