JP2009157074A - Beam control unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a beam control unit providing high luminance with no luminance unevenness nor moire while preventing luminance of light condensed at a front face with a prism sheet from being reduced. <P>SOLUTION: The beam control unit is provided with at least one light source 11, an optical sheet 14 disposed above the light source 11 and having a prism array structure on a light emission surface, and a diffusion sheet 15 disposed above the optical sheet 14 and having a fine three-dimensional structure 15a characterized by non-uniform and non-planar speckles. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light beam control unit, and more particularly, to a light beam control unit that can realize a display that has high luminance, no interference fringes (moire), and excellent uniformity of in-plane luminance when arranged on a display.

  Currently, liquid crystal display devices are used in a wide range of fields such as mobile phones, PDA terminals, digital cameras, televisions, personal computer displays, and notebook computers. In a liquid crystal display device, for example, a backlight unit is arranged behind a liquid crystal display panel, and an image is displayed by supplying light from the backlight unit to the liquid crystal display panel. The backlight unit used in such a liquid crystal display device is required not only to supply uniform light to the liquid crystal display panel but also to supply as much light as possible in order to make the display image easy to see. That is, the backlight unit is required to have optical characteristics such as excellent light diffusibility and high brightness.

  A conventional backlight unit, for example, a direct type backlight unit shown in FIG. 11, has a CCFL light source 111 and light emitted from the light source 111 in the direction of a liquid crystal display panel (not shown) (upward in FIG. Reflecting sheet 112 that plays a role of reflecting in the “front direction” and light from light source (line light source) 111 are diffused to form a surface light source, and the shape of light source 111 is not seen from the front direction. A diffusion plate 113 that plays a role of diffusing light, and further diffusing the light that has passed through the diffusion plate 113 so as not to make the shape of the light source 111 visible from the front direction, and condensing the light in the front direction to improve luminance. A diffusion sheet 114 that plays a role and a prism sheet 115 that collects light that has passed through the diffusion sheet 114 in the front direction to improve luminance. It is constructed from. As the diffusion sheet 114, a diffusion sheet formed by applying beads on the surface (upper main surface in FIG. 11) is used.

  Here, when the prism sheets are overlapped to improve the brightness, the generation of moire caused by the interference of light with other sheets, the reduction of the light collection characteristics due to excessive collection of light, the liquid crystal panel and the prism sheet Sticking or the like will occur. In addition, in order to prevent these problems, if a diffusion sheet having the same performance as a diffusion sheet having a high haze value and a high light diffusion property is disposed on the prism sheet, the light condensed on the front surface is re-diffused. As a result, there is a problem in that the front luminance decreases.

As means for solving the problem of lowering the front luminance, it has been proposed to use a diffusion sheet having a reduced haze value by reducing the amount of beads serving as a light diffusing agent (Patent Document 1).
Japanese Patent No. 3549491

  However, even with a diffusion sheet with a reduced amount of light diffusing agent, the rate of decrease in the front brightness of the light collected by the prism sheet is large, and by reducing the amount of light diffusing agent, the scratches made on the prism sheet can be easily seen. There was also a problem.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a light beam control unit that has a small amount of lowering the luminance focused on the front surface by a prism sheet, has high luminance, and has no luminance unevenness or moire. .

  As a result of intensive studies to develop a method for achieving the above object, the present inventors have found that an optical sheet having a fine three-dimensional structure is disposed on a prism sheet, and completed the present invention.

  That is, the light beam control unit of the present invention is provided at least one light source, an optical sheet disposed above the light source, having an arrayed prism arrangement structure on a light exit surface, and disposed above the optical sheet, And a diffusion sheet having a fine three-dimensional structure characterized by non-uniform non-planar speckles.

  In the light beam control unit of the present invention, the diffusion angle of the diffused light emitted from the diffusion sheet in the direction orthogonal to the ridge line extending direction of the prism array structure of the optical sheet is 0.1 ° to 30 °. Preferably there is.

  In the light beam control unit of the present invention, the diffusion angle of the diffused light emitted from the diffusion sheet in the direction parallel to the ridge line extending direction of the prism array structure of the optical sheet is 0.1 ° to 100 °. Preferably there is.

  In the light beam control unit of the present invention, it is preferable that the fine three-dimensional structure is constituted by a plurality of uneven structures, and the height and pitch of the uneven shapes are irregular.

In the light beam control unit of the present invention, it is preferable that another optical sheet having an arrayed prism arrangement structure is disposed on the light exit surface between the light source and the diffusion sheet.
It is about.

  The liquid crystal display device of the present invention comprises a liquid crystal display panel and the light beam control unit for supplying light to the liquid crystal display panel.

  According to the present invention, at least one light source, an optical sheet disposed above the light source and having an array-like prism arrangement structure on a light exit surface, and disposed above the optical sheet are non-uniform non-uniform. And a diffusion sheet having a fine three-dimensional structure characterized by planar speckles, so that the amount of light collected by the prism sheet on the front surface is small, the luminance is high, and there is no luminance unevenness or moire A control unit can be provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
1 to 4 are diagrams showing a schematic configuration of a light beam control unit according to an embodiment of the present invention. As the whole light beam control unit, a plurality of light sources 11 are used. As the light source 11, a linear light source such as a cold cathode fluorescent lamp (CCFL), or a point light source such as an LED (light emitting diode) or a laser can be used. The light source 11 may be arranged directly below the image display surface (FIGS. 1 and 2), or may be arranged at an edge with respect to the image display surface (FIGS. 3 and 4). ). In the case where the light source plate 11 is arranged in an edge shape, a light guide plate 12 for causing the light source 11 illuminated from the edge to emit light is used. Further, a reflection sheet 13 for reflecting light is used below the direct light source 11 or below the light guide plate 12 as an edge type.

  An optical sheet 14 having an array of prism arrangement structures on the light output surface is disposed above the light source 11 in the direct type or above the light guide plate 12 in the edge type.

  The array-like prism arrangement structure used in the present invention is an array of prisms arranged regularly. One prism has a substantially triangular cross section. Moreover, the ridgeline of the substantially triangular top part (part 14b with which the inclined surface 14a contacts) may extend linearly or may extend in a curved state. Further, the abutting portion 14b of the inclined surface may have a sharp corner or a rounded corner. The angle θ of the substantially triangular apex angle is preferably 45 ° or more and 135 ° or less in consideration of the fact that the light does not escape again and the ability to direct the light in the front direction.

  Further, the optical sheet 14 is not particularly limited as long as a prism array structure is formed. For example, a prism array structure may be formed of an acrylic resin or the like on a polyester film or the like, or a prism film structure may be directly formed on a polycarbonate film. As a specific example of a film, as a brightness enhancement film, Vikuiti (registered trademark) (manufactured by Sumitomo 3M, trade name) BEF series, BEFII series, BEFIII series, RBEF series, wave film series, etc. An equivalent film is listed.

  Above the optical sheet 14 having an arrayed prism arrangement structure, a diffusion sheet 15 having a non-planar speckle structure is disposed on the light incident surface and / or the light exit surface.

  The non-planar speckle structure of the diffusion sheet 15 used in the light beam control unit according to the present invention is an uneven shape 15a having a fine three-dimensional structure. This fine three-dimensional structure is composed of a plurality of concavo-convex structures, and the height and pitch of the concavo-convex shape are preferably irregular. The concave / convex shape 15a is a diffusion structure having a pseudo-random shape, and can be specifically formed as follows. First, a submaster mold in which a speckle pattern is formed in advance by interference exposure is manufactured, a metal is deposited on the submaster mold by a method such as electroforming, and the speckle pattern is transferred to the metal to manufacture a master mold. The speckle pattern is transferred to the light extraction surface of the light-transmitting resin layer by performing UV-shaped wrinkling on the light-transmitting resin layer using the master mold. A detailed manufacturing method of this sub-master type is disclosed in Japanese Patent No. 3341519. All this content is included here.

  The range of the diffusion angle can be controlled by adjusting the size, shape, and direction of the speckle pattern. In general, the range of the diffusion angle depends on the average size and shape of the speckle. If speckle is small, the angle range is wide. Further, if the speckle is an oblong in the horizontal direction, the shape of the angle distribution is an oblong in the vertical direction. Thus, the speckle pattern can be determined according to the desired directivity angle and diffusion angle. A detailed manufacturing method of this speckle pattern is disclosed in Japanese Patent No. 3390954. All this content is included here. The diffusion angle may be controlled by changing the pitch, height, and aspect ratio of the concavo-convex structure, or may be controlled by changing the refractive index of the light transmissive resin layer to be cured by ultraviolet rays.

  Here, the “diffusion angle” in the present invention refers to an angle (FWHM: Full Width Half Maximum) that is twice the angle at which the luminance attenuates to half of the peak luminance (half-value angle). This diffusion angle can be obtained, for example, by measuring the outgoing light distribution of light incident from a normal angle of 0 ° with a variable angle color difference meter of Nippon Denshoku Industries Co., Ltd.

  FIG. 5 is a schematic view showing an optical sheet having an arrayed prism arrangement structure that can be used in the light beam control unit according to the present invention, (a) is a cross-sectional view, and (b) is a front view. (C) is a perspective view. The ridge line extending direction (longitudinal direction) of the prism array (broken line in FIG. 5B) indicates the Y-axis direction in FIG. In the optical sheet 14 having a fine three-dimensional structure used in the present invention, the front brightness of the light control unit is increased, the degree of diffusion is sufficient, and the occurrence of moire is suppressed. It is preferable that the diffusion angle in a direction (direction along the ridge line) parallel to the ridge line extending direction (Y-axis direction in FIG. 5) is 0.1 ° to 100 °. It is preferable to use an optical sheet. More preferably, the diffusion angle in a direction parallel to the ridge line extending direction (direction along the ridge line) is not less than 0.5 ° and not more than 90 °.

  Further, with respect to a direction (X-axis direction in FIG. 5) perpendicular to the ridge line extending direction (longitudinal direction) of the prism array, the diffusion angle is set to 0. It is preferable that it is 1 degree or more and 30 degrees or less. More preferably, the diffusion angle is 0.5 ° or more and 20 ° or less, and particularly preferably 1 ° or more and 10 ° or less.

  In consideration of the front luminance and the like, the diffusion angle of the diffused light emitted from the diffusion sheet in the direction orthogonal to the ridge line extending direction (longitudinal direction) of the prism arrangement structure of the optical sheet is the prism arrangement structure of the optical sheet. It is preferable that it is below the diffusion angle of the diffused light emitted from the said diffusion sheet in the direction parallel to the ridgeline extending direction (longitudinal direction).

  The light beam control unit of the present invention includes at least one light source, an optical sheet disposed above the light source and having an array-like prism arrangement structure on a light exit surface, and disposed above the optical sheet. And a diffusion sheet having a fine three-dimensional structure characterized by uniform non-planar speckles. Therefore, if it has the said structure, you may arrange | position at least 1 optical sheet, a diffusion sheet, a diffusion plate, etc. further. For example, another optical sheet having an arrayed prism arrangement structure on the light output surface may be disposed between the light source 11 and the diffusion sheet 15.

  The light beam control unit according to the present invention can employ other arrangement configurations, for example, the arrangement configurations shown in FIGS. 6 to 9 using a diffusion sheet having a non-planar speckle structure. 6 to 9 are diagrams showing other configurations of the light beam control unit according to the embodiment of the present invention. As for the light source unit, the case where the direct type CCFL shown in FIG. 6 is used is described. As the light source unit, the direct type LED shown in FIG. 2, the edge type CCFL shown in FIG. 3, and the edge type LED shown in FIG. May be used.

  FIG. 6 is a diagram showing a configuration in which the diffusion sheet 17 formed by applying a diffusion plate 16 having an internal diffusing agent and spherical beads 17a on the surface between the light source 11 and the optical sheet 14 in the configuration shown in FIG. 11 shows a light beam control unit arranged in that order from the 11th side. As the diffusing plate 16, for example, polystyrene, cycloolefin polymer, acrylic resin, or the like added with an organic polymer or inorganic particles having an effect of diffusing light can be used. These diffusing plates 16 have the effect of diffusing light and making light from the lower light source uniform.

  As the diffusion sheet 17, a sheet in which spherical beads 17a of acrylic resin are applied on a polyester resin sheet can be used. Such a diffusion sheet 17 has a function of condensing the light diffused and made uniform by the diffusion plate 16 as well as the effect of diffusing and making the light uniform. By arranging an optical sheet 14 having an array-like prism arrangement structure and a diffusion sheet 15 having a fine concavo-convex structure characterized by a non-planar speckle structure together with these optical sheets 16 and 17, A light beam control unit having high luminance and low luminance unevenness can be realized.

  FIG. 7 shows a light beam control unit in which, in the configuration shown in FIG. 2, a diffusion plate 16 having the above internal diffusing agent is further disposed between the light source 11 and the optical sheet 14. With such a configuration, it is possible to realize a light beam control unit that has high front luminance and low luminance unevenness. Further, in such a configuration, the number of optical sheets can be reduced and the thickness can be reduced.

  FIG. 8 shows an optical sheet 18 having an arrayed prism arrangement structure on the light exit surface and a diffuser plate 16 having an internal diffusing agent between the light source 11 and the optical sheet 14 in the configuration shown in FIG. 11 shows a light beam control unit arranged in that order from the 11th side. The two arrayed prism sheets are arranged so that the arrayed ridge line extending directions (longitudinal directions) are orthogonal to each other. Thereby, although the viewing angle is reduced, it is possible to realize a light beam control unit with high front luminance and low luminance unevenness.

  FIG. 9 shows the configuration shown in FIG. 2 in which a diffusion plate 16 further having an internal diffusing agent and a diffusion sheet 15 characterized by non-planar speckles are disposed between the light source 11 and the optical sheet 14 on the light source 11 side. The light control units arranged in that order are shown. Thereby, compared with the case where the diffusion sheet 17 containing acrylic spherical beads is provided, the front luminance is improved and luminance unevenness can be eliminated.

  In the configuration shown in FIG. 9, the diffusion sheet 15 characterized by non-planar speckles disposed between the diffusion plate 16 and the optical sheet 14 having an array-like prism arrangement structure has an array-like prism arrangement structure. The diffusion sheet 15 may be the same as the diffusion sheet 15 disposed on the optical sheet 14, or a diffusion sheet designed to have a higher diffusion angle may be used. By using a diffusion sheet having a higher diffusion angle, the luminance unevenness can be further reduced.

  In the configurations shown in FIGS. 1 to 4 and FIGS. 6 to 9, the fine uneven structure 15 a characterized by the non-planar speckles of the diffusion sheet 15 is provided on the light exit surface (upper main surface in the drawing). However, as shown in FIG. 10, the fine concavo-convex structure 15 a may be provided on the light incident surface (lower main surface in the drawing) of the diffusion sheet 15. That is, the light emitted from the prism arrangement structure of the optical sheet 14 may be incident from a fine uneven structure and emitted from a surface that is not a fine uneven structure. Further, the fine concavo-convex structure 15a may be formed on both the light incident surface and the light exit surface.

  Further, as shown in FIGS. 1 to 4 and FIGS. 6 to 9, the diffusion sheet 15 having a fine uneven structure is incident on the light emitted from the prism array structure from a surface that is not a fine uneven structure, and the uneven structure is obtained. It is preferable to perform mat processing, sand blast processing, thin bead coating processing, or the like on a surface that is not a fine concavo-convex structure. By these treatments, it is possible to enhance the damage prevention effect of the arrayed prism arrangement structure.

  The light beam control unit can be applied to a liquid crystal display device by combining the liquid crystal display panel and supplying light to the liquid crystal display panel.

  Next, examples carried out to clarify the effects of the present invention will be described, but the present invention is not limited to these examples.

  LSD (registered trademark) sold by Luminit Corporation of the United States was used as a diffusion sheet having a fine concavo-convex structure characterized by non-planar speckles. The diffusion angle shown in the examples is an angle measured by using a variable angle color difference meter with light incident from a surface having a fine concavo-convex structure. For example, LSD 60 ° × 1 ° indicates that, for example, the FWHM in a certain direction is 60 °, and the value in a direction substantially orthogonal thereto is 1 °. Further, for example, LSD 5 ° indicates that the FWHM in any direction is 5 °.

  Optical sheets that are not described in the examples as optical sheets, that is, diffusion plates, diffusion sheets coated with beads, and optical sheets having an arrayed prism arrangement structure are used in the BRAVIA S-2500 manufactured by Sony Corporation. A diffusion plate (hereinafter abbreviated as DP), a diffusion sheet (hereinafter abbreviated as DS), and an optical sheet having an arrayed prism arrangement structure (hereinafter abbreviated as prism sheet) were used.

  In addition, a BRAVIA S-2500 CCFL light source was used as the light source of the light beam control unit. Luminance and luminance unevenness are set using a two-dimensional color luminance meter (CA2000) manufactured by Konica Minolta, placed 75 cm away from the light control unit, and the center of the light control unit is 40 mm × 210 mm [62 dots (x) × 322. The average luminance value measured in the range of dot (y)] was defined as luminance. The brightness unevenness is obtained as an average brightness value in the x-axis (40 mm) direction, and the brightness unevenness is obtained as a standard deviation value obtained by dividing the brightness value of each point by the brightness average value of ± 17 dots from each point in the y-axis direction. Asked.

1. In Examples 1 to 6 and Comparative Examples 1 to 4, the configurations of DP / DS / prism sheet / diffusion sheet were evaluated.

Example 1
As shown in FIG. 6, the light beam control unit of Example 1 was configured by arranging DP, DS, prism sheet, and LSD 60 ° × 1 ° from the light source. The ridge line extending direction (longitudinal direction) of the prism sheet is parallel to the CCFL light source, and LSD 60 ° × 1 ° is parallel to the ridge line extending direction (longitudinal direction) of the prism sheet (FIG. 5). And the diffusion angle in the Y-axis direction) was set to 60 °. The brightness, brightness unevenness value, and presence / absence of moire in the light beam control unit of Example 1 were examined by the above method. The results are shown in Table 1 below.

(Example 2)
Example similar to Example 1 except that LSD 60 ° × 4 ° (disposed so that the diffusion angle in the direction parallel to the ridge line extending direction of the prism sheet is 60 °) is provided on the prism sheet. Two light control units were constructed. The brightness, brightness unevenness value, and presence / absence of moire in the light beam control unit of Example 2 were examined by the above method. The results are also shown in Table 1 below.

(Example 3)
A light beam control unit of Example 3 was configured in the same manner as Example 1 except that LSD 1 ° was disposed on the prism sheet. The brightness, brightness unevenness value, and presence / absence of moire in the light beam control unit of Example 3 were examined by the above method. The results are also shown in Table 1 below.

Example 4
A light beam control unit of Example 4 was configured in the same manner as Example 1 except that LSD 5 ° was disposed on the prism sheet. The brightness, brightness unevenness value, and presence / absence of moire in the light beam control unit of Example 4 were examined by the above method. The results are also shown in Table 1 below.

(Example 5)
The light beam control unit of the fifth embodiment is the same as the first embodiment except that the LSD 1 ° is disposed on the prism sheet so that the light emitted from the prism sheet is incident on the uneven surface as shown in FIG. Configured. The brightness, brightness unevenness value, and presence / absence of moire in the light control unit of Example 5 were examined by the above method. The results are also shown in Table 1 below.

(Example 6)
A light beam control unit of Example 6 was configured in the same manner as Example 5 except that LSD 5 ° was disposed on the prism sheet. The brightness, the uneven brightness value, and the presence or absence of moire in the light control unit of Example 6 were examined by the above method. The results are also shown in Table 1 below.

(Comparative Example 1)
As shown in FIG. 11, DP, DS and prism sheet (the ridge line extending direction of the prism sheet is parallel to the CCFL light source) are arranged from the light source to constitute the light control unit of Comparative Example 1. The brightness, brightness unevenness value, and presence / absence of moire in the light control unit of Comparative Example 1 were examined by the above method. The results are also shown in Table 1 below.

(Comparative Example 2)
A light beam control unit of Comparative Example 2 was configured in the same manner as Comparative Example 1 except that the DS was disposed on the prism sheet. In the light beam control unit of Comparative Example 2, the brightness, the uneven brightness value, and the presence or absence of moire were examined by the above method. The results are also shown in Table 1 below.

(Comparative Example 3)
A light beam control unit of Comparative Example 3 was configured in the same manner as Comparative Example 1 except that a diffusion sheet BS082 (manufactured by Keiwa Co., Ltd., trade name) was disposed on the prism sheet. The brightness, the brightness unevenness value, and the presence or absence of moire in the light beam control unit of Comparative Example 3 were examined by the above method. The results are also shown in Table 1 below.

(Comparative Example 4)
A light beam control unit of Comparative Example 4 was configured in the same manner as Comparative Example 1 except that a diffusion sheet BS912 (trade name, manufactured by Keiwa Co., Ltd.) was disposed on the prism sheet. The brightness, the brightness unevenness value, and the presence or absence of moire in the light beam control unit of Comparative Example 4 were examined by the above method. The results are also shown in Table 1 below.

  From Table 1, the light control unit having the structure of the diffusion sheet having the fine uneven structure characterized by the DP / DS / prism sheet / non-planar speckle structure shown in FIG. 6 is DP / DS / prism sheet / spherical. It can be seen that the light control unit having a configuration of a diffusion sheet using beads has a better balance between luminance and luminance unevenness and no moiré compared to the arrangement of the DP / DS / prism sheet.

2. In Examples 7 to 9 and Comparative Examples 5 to 8, the configuration of the DP / prism sheet / diffusion plate was evaluated.

(Example 7)
As shown in FIG. 7, the light beam control unit of Example 7 was configured by arranging DP, prism sheet, and LSD 60 ° × 1 ° from the light source. The ridge line extending direction (longitudinal direction) of the prism sheet is parallel to the CCFL light source, and LSD 60 ° × 1 ° is parallel to the ridge line extending direction (longitudinal direction) of the prism sheet (FIG. 5). And the diffusion angle in the Y-axis direction) was set to 60 °. The brightness, brightness unevenness value, and presence / absence of moire in the light control unit of Example 7 were examined by the above method. The results are shown in Table 2 below.

(Example 8)
Example similar to Example 7 except that LSD 60 ° × 4 ° (arranged so that the diffusion angle in the direction parallel to the ridge line extending direction of the prism sheet is 60 °) is provided on the prism sheet. Eight light beam control units were constructed. The brightness, the uneven brightness value, and the presence or absence of moire in the light control unit of Example 8 were examined by the above method. The results are also shown in Table 2 below.

Example 9
Example similar to Example 7 except that LSD 70 ° × 1 ° (arranged so that the diffusion angle in the direction parallel to the ridge line extending direction of the prism sheet is 70 °) is provided on the prism sheet. Nine light beam control units were constructed. The brightness, brightness unevenness value, and presence / absence of moire in the light control unit of Example 9 were examined by the above method. The results are also shown in Table 2 below.

(Comparative Example 5)
The light source control unit of Comparative Example 5 was configured by arranging a DP and a prism sheet (the ridge line extending direction of the prism sheet is parallel to the CCFL light source) from the light source. The lightness control unit of Comparative Example 5 was examined for brightness, uneven brightness value, and the presence or absence of moire by the above method. The results are also shown in Table 2 below.

(Comparative Example 6)
A light beam control unit of Comparative Example 6 was configured in the same manner as Comparative Example 5 except that the DS was disposed on the prism sheet. In the light beam control unit of Comparative Example 6, the luminance, luminance unevenness value, and presence / absence of moire were examined by the above method. The results are also shown in Table 2 below.

(Comparative Example 7)
A light beam control unit of Comparative Example 7 was configured in the same manner as Comparative Example 5 except that a diffusion sheet BS072 (manufactured by Keiwa Co., Ltd., trade name) was disposed on the prism sheet. In the light control unit of Comparative Example 7, the luminance, the luminance unevenness value, and the presence or absence of moire were examined by the above method. The results are also shown in Table 2 below.

(Comparative Example 8)
A light beam control unit of Comparative Example 8 was configured in the same manner as Comparative Example 5 except that a diffusion sheet BS082 (manufactured by Keiwa Co., Ltd., trade name) was disposed on the prism sheet. The brightness, brightness unevenness value, and presence / absence of moire in the light control unit of Comparative Example 8 were examined by the above method. The results are also shown in Table 2 below.

  From Table 2, the light control unit having the structure of the diffusion sheet having the fine uneven structure characterized by the DP / prism sheet / non-planar speckle structure shown in FIG. 7 uses DP / prism sheet / spherical beads. It can be seen that the light beam control unit having the configuration of the diffusion sheet has a better balance between luminance and luminance unevenness and no moire compared to the arrangement of the DP / prism sheet.

3. In Examples 10 to 12, Comparative Example 9, and Comparative Example 10, the configuration of DP / prism sheet / prism sheet / diffusion plate was evaluated.

(Example 10)
As shown in FIG. 8, the light source control unit of Example 10 was configured by arranging DP, prism sheet, prism sheet, and LSDTM 1 ° × 1 ° from the light source. The ridge line extending direction (longitudinal direction) of the prism sheet near the light source is parallel to the CCFL light source. In addition, the upper (far from the light source) prism sheet was arranged so that the ridge lines of the lower (close to the light source) prism sheet were orthogonal to each other. The luminance, the luminance unevenness value, and the presence or absence of moire in the light beam control unit of Example 10 were examined by the above method. The results are shown in Table 3 below.

(Example 11)
A light beam control unit of Example 11 was configured in the same manner as Example 10 except that LSD 5 ° was disposed on the prism sheet. The luminance, the luminance unevenness value, and the presence or absence of moire in the light beam control unit of Example 11 were examined by the above method. The results are also shown in Table 3 below.

Example 12
The light beam control unit of the twelfth embodiment is similar to the tenth embodiment except that the LSD 5 ° is disposed on the prism sheet so that the light emitted from the prism sheet is incident on the uneven surface as shown in FIG. Configured. In the light beam control unit of Example 12, the luminance, the luminance unevenness value, and the presence or absence of moire were examined by the above method. The results are also shown in Table 3 below.

(Comparative Example 9)
The light control unit of Comparative Example 9 was configured by arranging DP, prism sheet, and prism sheet from the light source. The ridge line extending direction (longitudinal direction) of the prism sheet near the light source is parallel to the CCFL light source. In addition, the upper (far from the light source) prism sheet was arranged so that the ridge lines of the lower (close to the light source) prism sheet were orthogonal to each other. The brightness, brightness unevenness value, and presence / absence of moire in the light control unit of Comparative Example 9 were examined by the above method. The results are also shown in Table 3 below.

(Comparative Example 10)
The light control unit of Comparative Example 10 was configured in the same manner as Comparative Example 9 except that the DS was disposed on the prism sheet. In the light control unit of Comparative Example 10, the brightness, the uneven brightness value, and the presence or absence of moire were examined by the above method. The results are also shown in Table 3 below.

  From Table 3, the light beam control unit having the structure of the diffusion sheet having the fine uneven structure characterized by the DP / prism sheet / prism sheet / non-planar speckle structure shown in FIG. 8 is DP / prism sheet / prism sheet. / It can be seen that the light intensity control unit has a better balance between luminance and luminance unevenness than the light beam control unit having the configuration of a diffusion sheet using spherical beads, and that there is no moire compared to the arrangement of DP / prism sheet / prism sheet.

  The present invention can be applied to an illumination device such as a backlight of a liquid crystal display unit of a liquid crystal television, a digital camera, a mobile phone or the like.

It is a figure which shows the structure of the light beam control unit which concerns on embodiment of this invention. It is a figure which shows the structure of the light beam control unit which concerns on embodiment of this invention. It is a figure which shows the structure of the light beam control unit which concerns on embodiment of this invention. It is a figure which shows the structure of the light beam control unit which concerns on embodiment of this invention. It is the schematic which shows the optical sheet which has an array-like prism arrangement | sequence structure which can be used for the light beam control unit which concerns on this invention, (a) is sectional drawing, (b) is a front view, (c ) Is a perspective view. It is a figure which shows the other example of a structure of the light beam control unit which concerns on embodiment of this invention. It is a figure which shows the other example of a structure of the light beam control unit which concerns on embodiment of this invention. It is a figure which shows the other example of a structure of the light beam control unit which concerns on embodiment of this invention. It is a figure which shows the other example of a structure of the light beam control unit which concerns on embodiment of this invention. It is a figure which shows the other example of a structure of the light beam control unit which concerns on embodiment of this invention. It is a figure which shows the conventional backlight unit structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Light source 12 Light guide plate 13 Reflection sheet 14,18 Optical sheet 14a Inclined surface 14b Top part 15,17 Diffusion sheet 15a Fine uneven structure 16 Diffusion plate 17a Spherical bead

Claims (6)

  Characterized by at least one light source, an optical sheet disposed above the light source and having an arrayed prism array structure on the light exit surface, and an uneven non-planar speckle disposed above the optical sheet. And a diffusion sheet having a fine three-dimensional structure.   The diffusion angle of diffused light emitted from the diffusion sheet in a direction orthogonal to the ridge line extending direction of the prism array structure of the optical sheet is 0.1 ° or more and 30 ° or less. The light beam control unit described in 1.   The diffusion angle of diffused light emitted from the diffusion sheet in a direction parallel to the ridge line extending direction of the prism array structure of the optical sheet is 0.1 ° to 100 °. Alternatively, the light beam control unit according to claim 2.   The light beam according to any one of claims 1 to 3, wherein the fine three-dimensional structure is composed of a plurality of uneven structures, and the uneven shapes have irregular heights and pitches. Controller unit.   5. The optical sheet according to claim 1, wherein another optical sheet having an arrayed prism arrangement structure is disposed between the light source and the diffusion sheet. Light control unit.   A liquid crystal display device comprising: a liquid crystal display panel; and the light beam control unit according to claim 1 for supplying light to the liquid crystal display panel.

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