WO2009116458A1 - 光学素子、それを備えた光源ユニット及び液晶表示装置 - Google Patents
光学素子、それを備えた光源ユニット及び液晶表示装置 Download PDFInfo
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- WO2009116458A1 WO2009116458A1 PCT/JP2009/054853 JP2009054853W WO2009116458A1 WO 2009116458 A1 WO2009116458 A1 WO 2009116458A1 JP 2009054853 W JP2009054853 W JP 2009054853W WO 2009116458 A1 WO2009116458 A1 WO 2009116458A1
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- microlens
- microlens array
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/133526—Lenses, e.g. microlenses or Fresnel lenses
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B3/00—Simple or compound lenses
- G02B3/0006—Arrays
- G02B3/0037—Arrays characterized by the distribution or form of lenses
- G02B3/0056—Arrays characterized by the distribution or form of lenses arranged along two different directions in a plane, e.g. honeycomb arrangement of lenses
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/1336—Illuminating devices
- G02F1/133602—Direct backlight
- G02F1/133603—Direct backlight with LEDs
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/1336—Illuminating devices
- G02F1/133602—Direct backlight
- G02F1/133604—Direct backlight with lamps
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/1336—Illuminating devices
- G02F1/133602—Direct backlight
- G02F1/133611—Direct backlight including means for improving the brightness uniformity
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/1336—Illuminating devices
- G02F1/133602—Direct backlight
- G02F1/133606—Direct backlight including a specially adapted diffusing, scattering or light controlling members
- G02F1/133607—Direct backlight including a specially adapted diffusing, scattering or light controlling members the light controlling member including light directing or refracting elements, e.g. prisms or lenses
Definitions
- the present invention relates to an optical element, a light source unit including the optical element, and a liquid crystal display device.
- a so-called direct-type backlight is known.
- the direct type backlight a plurality of light sources are arranged below the light emitting surface. For this reason, in the light-projection surface of a backlight, it exists in the tendency for the brightness
- Patent Documents 1 to 5 have proposed various methods for eliminating the uneven luminance.
- Patent Document 1 discloses a method of arranging a light diffusing plate using a light diffusing material on a light source.
- Patent Document 6 discloses an optical sheet having a microlens array having a microlens diameter of 10 ⁇ m or more and less than 100 ⁇ m. Patent Document 6 describes that according to this optical sheet, high brightness and uniform brightness in the front direction can be achieved. Further, in Patent Document 6, if the diameter of the microlens is smaller than 10 ⁇ m, the influence of diffraction becomes large and the visual quality is deteriorated. Therefore, the diameter of the microlens is preferably 10 ⁇ m or more, more preferably 20 ⁇ m or more. It is described that it is particularly preferable. JP 54-155244 A Japanese Patent No. 2852424 JP 2000-338895 A JP 2002-352611 A US Pat. No. 5,161,041 JP 2004-145329 A
- Patent Documents 2 to 5 can eliminate uneven brightness of the backlight having linear light sources arranged in parallel to each other, the backlights in which the point light sources are arranged in a matrix form. There is a problem that it is difficult to sufficiently eliminate uneven brightness of the light. Specifically, although it is possible to eliminate the luminance unevenness of the backlight in a predetermined direction, there is a problem that it is difficult to sufficiently eliminate the luminance unevenness of the backlight in a direction perpendicular to the predetermined direction.
- the present invention has been made in view of the above points, and its object is to have high light extraction efficiency, and also to prevent uneven luminance in two orthogonal directions of a backlight in which point light sources are arranged in a matrix.
- An object of the present invention is to provide an optical element that can be eliminated.
- An optical element includes an optical sheet having a light incident surface and a light exit surface, and a light diffusion sheet that is disposed on the light exit surface side of the optical sheet and diffuses by refracting incident light. Yes.
- a microlens array is formed on at least one of the light incident surface and the light emitting surface.
- a plurality of microlenses formed in a convex shape or a concave shape are arranged periodically and in a matrix at a pitch of less than 10 ⁇ m.
- the microlens is formed in a convex shape, and the microlens array is formed on the light exit surface.
- the pitch of the microlens array is preferably 5 ⁇ m or less, and more preferably 3 ⁇ m or less.
- the light diffusion sheet has a microlens array in which a plurality of microlenses are arranged at a pitch of 10 ⁇ m or more.
- the microlens of the optical sheet is substantially circular in plan view, and the diameter of the microlens of the optical sheet in plan view is 50% or more of the pitch of the microlens array of the optical sheet, Preferably it is 80% or more.
- the occupation ratio of the microlens on the surface on which the microlens array is formed of the light incident surface and the light emitting surface is 80% or more.
- the coordinate system shown in FIG. 17 where the pitch ( ⁇ m) is the X axis and the micro lens aspect ratio obtained by dividing the microlens height by the microlens diameter is the Y axis
- the coordinate system shown in FIG. The aspect ratio of the micro lens is point A (1.0, 0.875), point B (1.0, 0.625), point C (1.5, 0.375), point D (2.0 , 0.375), point E (2.0, 0.625), and point F (1.5, 0.875) are located in a region formed by connecting straight lines in this order.
- the microlens array pitch ( ⁇ m) is the X axis
- the microlens aspect ratio obtained by dividing the microlens height by the microlens diameter is the Y axis.
- pitch of microlens array, aspect ratio of microlens is point G (1.0, 0.75), point H (1.5, 0.5), and point I (2 .0, 0.5) and point J (1.5, 0.75) are located in a region formed by connecting them in this order with a straight line.
- the microlens array is formed such that the optical sheet has a peak of transmitted light having a transmittance higher than that at a diffusion angle of 0 ° at a diffusion angle other than 0 °. ing.
- the plurality of microlenses are regularly and periodically arranged in both the first direction and the second direction orthogonal to the first direction.
- the plurality of microlenses of the optical sheet are arranged so that a figure formed by connecting the centers of adjacent microlenses becomes a regular triangle in plan view.
- the light source unit according to the present invention includes the optical element according to the present invention and a light source device.
- the light source device is disposed on the light incident surface side of the optical element.
- the light source device emits light toward the light incident surface.
- the light source device may have a plurality of point light sources.
- the liquid crystal display device includes the light source unit according to the present invention and a liquid crystal display cell disposed on the light emitting surface side of the light diffusion sheet.
- the optical sheet has a microlens array with a pitch of less than 10 ⁇ m, and the light diffusion sheet that diffuses by refracting incident light is disposed on the light exit surface side of the optical sheet.
- Light extraction efficiency can be increased, and uneven brightness in two orthogonal directions of a backlight in which point light sources are arranged in a matrix can also be eliminated.
- FIG. 1 is a schematic cross-sectional view of a liquid crystal display device according to an example of a preferred embodiment in which the present invention is implemented.
- FIG. 2 is a plan view showing a part of the light diffusion sheet.
- 3 is a view taken in the direction of arrows III-III in FIG.
- FIG. 4 is a plan view showing a part of the optical sheet.
- FIG. 5 is a VV arrow view in FIG.
- FIG. 6 is a plan view of the light source device. However, illustration of the translucent substrate 33 is omitted.
- FIG. 7 is a graph showing the relationship between the diffusion angle and the transmittance when the pitch of the microlens array is 50 ⁇ m.
- FIG. 8 is a graph showing the relationship between the diffusion angle and the transmittance when the pitch of the microlens array is 9.9 ⁇ m.
- FIG. 9 is a graph showing the relationship between the diffusion angle and the transmittance when the pitch of the microlens array is 5 ⁇ m.
- FIG. 10 is a graph showing the relationship between the diffusion angle and the transmittance when the pitch of the microlens array is 3 ⁇ m.
- FIG. 11 is a graph showing the relationship between the diffusion angle and the transmittance when the pitch of the microlens array is 1.8 ⁇ m.
- FIG. 13 is a plan view illustrating a part of the optical sheet in the first modification.
- FIG. 14 is a plan view of the light source device according to the second modification.
- FIG. 15 is a view taken along arrow XV-XV in FIG.
- FIG. 16 is a cross-sectional view illustrating a part of the optical sheet in Modification 3.
- FIG. 17 is a graph showing the relationship between the pitch of the microlens array and the aspect ratio of the microlens.
- liquid crystal display device 1 shown in FIG. 1 as an example.
- the liquid crystal display device 1 is merely an example, and the present invention is not limited to the liquid crystal display device 1.
- the liquid crystal display device 1 includes a liquid crystal display cell 40, a pair of polarizing plates 41 a and 41 b, and a light source unit 2.
- the liquid crystal display cell 40 is disposed between the pair of polarizing plates 41a and 41b.
- the polarizing plate 41a and the polarizing plate 41b are disposed so that the polarization directions are orthogonal to each other.
- the light source unit 2 includes a light source device 30 and an optical element 3.
- the light source device 30 is not particularly limited.
- the light source device 30 may include a plurality of point light sources such as LEDs (Light Emitting Diode).
- the light source device 30 may have a plurality of linear light sources such as cold cathode tubes.
- the light source device 30 includes a casing 31, a plurality of point light sources 32, and a translucent substrate 33, as shown in FIG.
- a recess 31 a is formed in the casing 31.
- the plurality of point light sources 32 are disposed in the recess 31a.
- the plurality of point light sources 32 are arranged periodically and in a matrix. In FIG. 6, the drawing of the transparent substrate 33 is omitted.
- the recess 31 a of the casing 31 is covered with a light transmitting substrate 33.
- the light from the point light source 32 is emitted from the translucent substrate 33.
- the translucent substrate 33 may be a diffusion plate having a function of diffusing light, for example. Further, a light diffusing plate may be further disposed on the translucent substrate 33.
- the optical element 3 is arranged on the light emitting surface 30 a side of the light source device 30.
- the optical element 3 includes a light transmissive optical sheet 20 and a light transmissive light diffusion sheet 10.
- the optical sheet 20 is disposed on the light emitting surface 30 a of the light source device 30.
- the light diffusion sheet 10 is disposed on the light emitting surface 20b side of the optical sheet 20. Specifically, in this embodiment, the light diffusion sheet 10 is disposed above the light emitting surface 20b. The light diffusion sheet 10 diffuses the incident light incident from the optical sheet 20 side by refracting it.
- the light diffusion sheet is not particularly limited as long as it diffuses the incident light by refracting it.
- the light diffusion sheet 10 may be, for example, a bead-coated light diffusion sheet, a prism sheet, a reflective polarization functional sheet, or the like.
- one light diffusion sheet 10 is arranged, but a plurality of light diffusion sheets 10 may be arranged.
- a plurality of light diffusion sheets 10 When a plurality of light diffusion sheets 10 are arranged, a plurality of light diffusion sheets of the same type may be arranged, or a plurality of types of light diffusion sheets may be arranged.
- the light diffusion sheet 10 includes a light incident surface 10a and a light emitting surface 10b.
- the light diffusion sheet 10 includes a microlens array 11 formed on the light emitting surface 10b.
- the microlens array 11 includes a plurality of microlenses 12 arranged periodically and in a matrix.
- the arrangement of the plurality of microlenses 12 is not particularly limited.
- the plurality of microlenses 12 may be regularly and periodically arranged in each of a first direction and a second direction orthogonal to the first direction. That is, the plurality of microlenses 12 may be arranged in a so-called square lattice pattern.
- the plurality of microlenses 12 have a so-called triangular lattice pattern (preferably a regular triangle) so that a figure formed by connecting the centers of adjacent microlenses 12 in a plan view is a triangle (preferably a regular triangle).
- they may be arranged in an equilateral triangular lattice pattern.
- a so-called equilateral triangle lattice pattern is used so that the figure T 1 connecting the centers C 1 to C 3 of the adjacent microlenses 12 becomes an equilateral triangle. It is arranged.
- the number of microlenses 12 arranged per unit area can be increased. That is, the occupation ratio of the microlens 12 can be increased. Therefore, a high diffusion function can be realized.
- the microlens 12 has a hemispherical shape.
- the shape of the microlens 12 is not particularly limited.
- the microlens 12 may be formed in, for example, an oval shape, a cone shape, a truncated cone shape, a pyramid shape, or a truncated pyramid shape.
- the plurality of microlenses 12 are arranged at a pitch of 10 ⁇ m or more.
- the pitch of the microlens array 11 is preferably 20 ⁇ m or more, for example.
- the “microlens array pitch” refers to the shortest distance among the distances between the centers of adjacent microlenses. Specifically, in the case shown in FIG. 2, the plurality of microlenses 12 are arranged so that the figure formed by connecting the centers of the adjacent microlenses 12 is an equilateral triangle, and therefore the pitch P 1 shown in FIG. And the pitch P 2 are equal. Therefore, the pitch P of the microlens array 11 in this embodiment is equal to the pitch P 1 and the pitch P 2.
- the diameter D 1 of the micro lens 12 is not particularly limited.
- the diameter D 1 of the micro lens 12, the pitch P of the microlens array 11 can be appropriately set according to the occupancy.
- the diameter D 1 of the microlens 12 can be about 15 to 100 ⁇ m.
- the material of the light diffusion sheet 10 is not particularly limited.
- the light diffusion sheet 10 may be formed of, for example, a synthetic resin.
- Specific examples of the synthetic resin include, for example, polyethylene terephthalate.
- the average thickness of the light diffusion sheet 10 is not particularly limited.
- the average thickness of the light diffusion sheet 10 is preferably about 50 to 400 ⁇ m, for example.
- the optical sheet 20 is disposed on the light source device 30.
- the optical sheet 20 does not necessarily need to be disposed immediately above the light source device 30.
- Another optical element may be disposed between the light source device 30 and the optical sheet 20.
- a light diffusing plate or a prism sheet may be disposed between the optical sheet 20 and the light source device 30.
- an air layer may be interposed between the light source device 30 and the optical sheet 20.
- the optical sheet 20 includes a light incident surface 20a and a light emitting surface 20b.
- the light incident surface 20 a faces the light source device 30.
- the light emission surface 20 b faces the light diffusion sheet 10.
- the optical sheet 20 includes a microlens array 21 as shown in FIGS.
- the microlens array 21 is formed on at least one of the light incident surface 20a and the light emitting surface 20b. Specifically, in the present embodiment, as shown in FIGS. 1 and 5, the light emitting surface 20 b of the optical sheet 20 is formed.
- the microlens array 21 includes a plurality of microlenses 22. Each of the plurality of microlenses 22 is formed in a convex shape or a concave shape. In the present embodiment, the microlens array 21 includes a plurality of microlenses 22 formed in a convex shape. More specifically, in the present embodiment, the microlens 22 is formed in a hemispherical shape. However, in the present invention, the shape of the microlens 22 is not limited to this. The microlens 22 may be formed in a shape such as an elliptical sphere, a cone, a truncated cone, a pyramid, or a truncated pyramid.
- the plurality of microlenses 22 are arranged periodically and in a matrix.
- the plurality of microlenses 22 may be regularly and periodically arranged in both the first direction and the second direction orthogonal to the first direction. That is, the plurality of microlenses 22 may be arranged in a so-called square lattice pattern, for example.
- a plurality of micro lenses 22 are graphic T 2 formed by connecting the center C 4 ⁇ C 6 microlenses 22 adjacent may be arranged such that the triangle. That is, the plurality of microlenses 22 may be arranged in a so-called triangular lattice pattern.
- the pitch of the microlens array 21 is preferably 5 ⁇ m or less, more preferably 3 ⁇ m or less, and even more preferably 2.5 ⁇ m or less.
- the pitch P of the microlens array 21 is preferably 0.3 ⁇ m or more, and more preferably 0.7 ⁇ m or more. This is because if the pitch P of the microlens array 21 is reduced, the formation of the microlens array 21 tends to be difficult.
- the pitch P of the microlens array 21 is set to be less than 10 ⁇ m, diffracted light is generated in the microlens array 21.
- the diffracted light strengthens at an angle ⁇ that satisfies the following formula (1).
- P ⁇ sin ⁇ n ⁇ (1)
- P pitch of the microlens array 21
- n natural number
- ⁇ wavelength of light incident on the microlens array 21, It is.
- the diameter D 2 of the micro lens 22 is not particularly limited.
- the diameter D 2 of the micro lenses 22 is preferably at least 50% of the pitch P of the microlens array 21 is preferably 80% or more.
- the occupation ratio of the microlens 22 is preferably 20% or more, and more preferably 50% or more.
- the occupation ratio of the microlens is a ratio of the area of the microlens to the area of the surface on which the microlens is formed in a plan view. Specifically, in the case shown in FIG. 4, the ratio of the area of the microlens 22 to the area of an equilateral triangle T 2 surrounded by the center C 4 ⁇ C 6 microlenses 22, which is located within the equilateral triangle T 2 Say.
- the material of the optical sheet 20 is not particularly limited as long as it has optical transparency.
- the optical sheet 20 can be formed of, for example, a light transmissive synthetic resin.
- the synthetic resin include, for example, polyethylene terephthalate, polyethylene naphthalate, acrylic resin, polycarbonate, polystyrene, polyolefin, cellulose acetate, weather resistant vinyl chloride, and energy curable resin.
- the energy curable resin include an ultraviolet curable resin and an electron beam curable resin. Among these, energy curable resins typified by ultraviolet curable resins and electron beam curable resins are particularly preferable. This is because the microlens array 21 can be formed relatively easily by using the energy curable resin.
- the optical sheet 20 may be integrally formed, or may be a laminate of a plurality of optical members. Specifically, a microlens formed of an ultraviolet curable resin or the like may be attached to an optical film such as a polyethylene terephthalate film, a polyethylene naphthalate film, or a polycarbonate film.
- the optical sheet 20 may contain at least one of various fillers, plasticizers, stabilizers, deterioration inhibitors, dispersants, and the like.
- the thickness of the optical sheet 20 is not particularly limited.
- the average thickness of the optical sheet 20 may be, for example, 10 ⁇ m or more and 3000 ⁇ m or less. Considering the light transmittance of the optical sheet 20, the average thickness of the optical sheet 20 is preferably 35 ⁇ m or more and 300 ⁇ m or less, and more preferably 50 ⁇ m or more and 250 ⁇ m or less.
- the preferable range of the average thickness of the optical sheet 20 is 1000 ⁇ m or more and 2500 ⁇ m or less, and more preferably 1200 ⁇ m or more and 2000 ⁇ m or less.
- the thickness of the optical sheet 20 is too thin, the shape of the optical sheet 20 may change due to heat from the light source device 30 or the like. On the other hand, if the optical sheet 20 is too thick, the light transmittance of the optical sheet 20 tends to decrease.
- the manufacturing method of the optical sheet 20 is not particularly limited.
- the optical sheet 20 can be manufactured by various known manufacturing methods.
- the optical element 3 of the present embodiment includes the microlens array 21 having a pitch P of less than 10 ⁇ m and the light diffusion sheet 10 that diffuses the incident light by refracting it. Therefore, for example, both high light extraction efficiency and high light diffusivity are realized as compared with the case where only the light diffusion plate that diffuses light by refracting light is used instead of the optical element 3.
- the pitch of the microlens array 21 is normally set to 10 ⁇ m or more from the viewpoint of suppressing chromatic dispersion.
- the pitch of the microlens array 21 is 10 ⁇ m or more, it is difficult to sufficiently diffuse light.
- the light diffusion sheet 10 that diffuses the incident light by refracting it is combined with the microlens array 21 having high light diffusion ability. Therefore, chromatic dispersion generated in the microlens array 21 can be effectively eliminated in the light diffusion sheet 10 while realizing high light diffusibility in the microlens array 21. Therefore, it is possible to effectively suppress the rainbow-colored pattern due to color dispersion from being visually recognized while realizing high light diffusibility.
- a plurality of minute microlenses 22 are arranged in a matrix. For this reason, light can be dispersed not only in one direction but also in two directions orthogonal to each other. Therefore, by using the optical element 3, it is possible to eliminate uneven brightness in two orthogonal directions of a backlight in which point light sources are arranged in a matrix.
- FIG. 7 is a graph showing the relationship between the diffusion angle of the emitted light and the transmittance in a microlens array having a pitch of 50 ⁇ m.
- a microlens array having a pitch of 50 ⁇ m substantially no diffracted light is generated in the microlens array.
- FIGS. 7 to 12 are graphs when the wavelength of incident light is 550 nm.
- FIG. 8 is a graph showing the relationship between the diffusion angle and transmittance of outgoing light in the microlens array 21 with a pitch of 9.9 ⁇ m.
- the microlens array 21 having a pitch of 9.9 ⁇ m, diffracted light is generated in the microlens array 21.
- the pitch of the microlens array 21 is 50 ⁇ m, the transmittance at a diffusion angle of 0 degrees is lowered, and the transmittance at a diffusion angle of ⁇ 30 to 0 degrees and 0 to 30 degrees is increased. Therefore, uneven brightness can be reduced.
- diffracted light may be generated even when the pitch of the microlens array is 10 ⁇ m or more.
- the pitch of the microlens array is 10 ⁇ m or more
- the obtained diffusion angle becomes very small. Accordingly, when the pitch of the microlens array is 10 ⁇ m or more, light cannot be sufficiently diffused. As a result, it becomes difficult to sufficiently suppress luminance unevenness.
- FIGS. 9 to 11 are graphs showing the relationship between the diffusion angle and the transmittance of the emitted light in the microlens array 21 having the pitch of the microlens array 21 of 5 ⁇ m, 3 ⁇ m, and 1.8 ⁇ m, respectively.
- FIG. 8 when the pitch of the microlens array 21 is 9.9 ⁇ m, a plurality of transmitted light peaks appear, but a plurality of transmitted light peaks are close to each other.
- the pitch of the microlens array 21 is 5 ⁇ m or less, the distance between the peaks of adjacent transmitted light becomes wide, and there are many other than just above the point light source 32. The peaks of transmitted light are scattered.
- the pitch of the microlens array 21 is preferably 5 ⁇ m or less.
- the pitch of the microlens array 21 increases particularly rapidly when it becomes 3 ⁇ m. For this reason, the pitch of the microlens array 21 is more preferably 3 ⁇ m or less.
- the transmitted light intensity directly above the point light source 32 is preferably small.
- the transmittance at a diffusion angle of 0 degree is small.
- the transmittance of the peak of transmitted light at a diffusion angle of 0 degrees is lower than the transmittance of the peak of transmitted light at a diffusion angle other than 0 degrees.
- the optical sheet 20 has a peak of transmitted light having a transmittance higher than the transmittance at a diffusion angle of 0 degrees at a diffusion angle other than 0 degrees.
- the ratio (occupancy ratio) of the microlens 22 to the light exit surface 20b of the optical sheet 20 is large. More specifically, the occupation ratio of the microlens 22 in the region where the microlens array 21 is formed on the light emitting surface 20b is preferably 20% or more, and more preferably 50% or more. By doing so, it is possible to reduce the amount of light transmitted without diffusing the optical sheet 20 and increase the diffracted light.
- the diameter of the microlens 22 is preferably 50% or more of the pitch of the microlens array 21, and is 80% or more. It is more preferable that
- the microlenses 22 are arranged so that the figure formed by connecting the centers of the adjacent microlenses 22 in a plan view is a triangle as shown in FIG. It is preferable. Furthermore, it is particularly preferable that the microlenses 22 are arranged so that the figure formed by connecting the centers of the adjacent microlenses 22 is a regular triangle in plan view. This is because the occupation ratio of the microlens 22 can be maximized.
- the occupation ratio of the microlens 12 on the light exit surface 20b is 80% or more, and the pitch ( ⁇ m) of the microlens array 11 is the X axis.
- the aspect ratio of the microlens 12 obtained by dividing the height of 12 by the diameter of the microlens 12 is the Y axis, (microlens array pitch, microlens aspect ratio) is Point A (1.0, 0.875), Point B (1.0, 0.625), Point C (1.5, 0.375), Point D (2.0, 0.375), Point E (2.0, 0.625) and the point F (1.5, 0.875) are preferably located within a region X1 formed by connecting straight lines in this order.
- pitch of microlens array, aspect ratio of microlens is point G (1.0, 0.75), point H (1.5, 0.5), point More preferably, it is located in a region X2 formed by connecting I (2.0, 0.5) and point J (1.5, 0.75) in this order with a straight line. That is, when the micro lens 22 has an aspect ratio of 0.5, that is, when the micro lens 22 has a hemispherical shape, the pitch of the micro lens array 21 is preferably 1.25 to 2.0 ⁇ m, More preferably, it is -2.0 ⁇ m. According to this configuration, the transmittance at a diffusion angle of 0 degrees can be set to 30% or less, and the transmittance at a diffusion angle other than 0 degrees can be set to 2% or more.
- the type of the light diffusion sheet 10 is not particularly limited. However, it is preferable that the light diffusion sheet 10 has the microlens array 11 in which the pitch of the microlens array 11 is 10 ⁇ m or more as in the present embodiment.
- a sheet having the microlens array 11 is used as the light diffusion sheet, for example, light diffusion in an unnecessary direction and light absorption by the light diffusion material are performed as in the case of using a light diffusion sheet using a light diffusion material. Can be suppressed. Therefore, higher light extraction efficiency can be realized.
- the minimum function required for the light diffusing sheet 10 is only a function for eliminating the color dispersion generated in the optical sheet 20.
- the light diffusion sheet 10 is required as compared with the light diffusion plate in the case where only the light diffusion plate that diffuses by refracting light instead of the optical element 3 is arranged instead of the optical element 3.
- Light diffusivity is relatively low. Therefore, for example, when the light diffusion sheet 10 is configured by a light diffusion sheet using a light diffusion material, the concentration of the light diffusion material in the light diffusion sheet 10 can be reduced.
- the microlens 22 is formed in a convex shape and the microlens array 21 is formed on the light emitting surface 20b of the optical sheet 20. According to this, the light diffusion performance of the optical sheet 20 can be further increased.
- the arrangement of the microlenses 22 is not limited to a so-called equilateral triangular lattice arrangement.
- the microlenses 22 may be regularly and periodically arranged in the x direction and the y direction orthogonal to each other.
- the pitch of the microlens array 21 is substantially the same in the x and y directions. can do. For this reason, the light diffusion performance of the optical sheet 20 in the x direction and the light diffusion performance of the optical sheet 20 in the y direction can be made substantially the same.
- the type of light source provided in the light source device 30 is not limited to a point light source.
- the light source device 30 may include a plurality of linear light sources 34 arranged in parallel as shown in FIGS. 14 and 15, for example.
- the type of the linear light source 34 is not particularly limited.
- the linear light source 34 may be, for example, a cold cathode fluorescent lamp (CCFL).
- the microlens array 21 having the plurality of microlenses 22 formed in a convex shape is formed on the light emitting surface 20b of the optical sheet 20 has been described.
- the microlens 22 may be concave.
- the microlens array 21 may be formed on the light incident surface 20 a of the optical sheet 20.
- the microlens array 21 may be formed on both the light emitting surface 20b and the light incident surface 20a of the optical sheet 20.
- a microlens array 21 having a plurality of concave microlenses 25 may be formed on the light incident surface 20 a of the optical sheet 20.
- a plurality of at least one of the optical sheet 20 and the light diffusion sheet 10 may be arranged. That is, the arrangement number of the optical sheet 20 and the light diffusion sheet 10 is not limited to one.
- the microlens array 21 may be covered with a translucent member. That is, the microlens array 21 may be formed at the interface between the optical sheet 20 and the translucent member.
- optical elements may be disposed between the optical sheet 20 and the light source device 30 or between the optical sheet 20 and the light diffusion sheet 10.
- a further light diffusion sheet may be disposed between the optical sheet 20 and the light source device 30.
- the microlens array 21 may be formed on the surface of another optical element. For example, it may be formed on the surface of the translucent substrate 33 shown in FIG.
- Matting may be applied to at least one surface of the optical sheet 20. Further, an anti-sticking layer in which bead particles are dispersed in a binder may be formed on at least one surface of the optical sheet 20. That is, the surface roughness of at least one surface of the optical sheet 20 may be roughened. By doing so, sticking of the optical sheet 20 with respect to the translucent substrate 33 and the like can be suppressed.
- Example 1 First, by roll-pressing a polycarbonate film (product name: Panlite 1225LL, manufactured by Teijin Chemicals Ltd.) having a length of 10 cm, a width of 10 cm, and a thickness of 200 ⁇ m, a substantially hemispherical microlens 22 having a diameter of 9.4 ⁇ m is shown in FIG. An optical sheet 20 formed with a regular triangular lattice pattern with a pitch of 9.9 ⁇ m was obtained. The occupation ratio of the microlens 22 was 81.8%.
- a polycarbonate film product name: Panlite 1225LL, manufactured by Teijin Chemicals Ltd.
- a light diffusion sheet 10 (product number: 100DX2 manufactured by Kimoto Co., Ltd.) having a light diffusion layer in which styrene beads are dispersed in an acrylic binder and formed on a polyethylene terephthalate (PET) substrate having a thickness of 100 ⁇ m was used as the light diffusion sheet 10.
- an LED light source (product number: E1S27 * M1F7-03 manufactured by Toyoda Gosei) was used. Twenty-five LED light sources were arranged on the circuit board at intervals of 1.9 cm in length and width, and wired to the circuit board.
- a white polyester film (product number: Lumirror E6SL, manufactured by Toray Industries, Inc., thickness: 250 ⁇ m) is affixed to the portion excluding the LED light source of the circuit board and the inner surface of the casing 31, and a diffusion plate (grade MS) manufactured by Asahi Kasei Chemicals , A thickness of 2 mm) is disposed as the light-transmitting substrate 33, thereby producing a light source device 30 having a 100 mm square and a height of 13.5 mm.
- the light source device 30, the light diffusion sheet 10, and the optical sheet 20 produced as described above were laminated in the order shown in FIG.
- the luminance and luminance unevenness of the obtained light source unit 2 were measured as follows. That is, a viewing angle characteristic measuring device (product name: EZContrast 80, manufactured by ELDIM) is fixed to 1.2 mm above the light exit surface of the light diffusion sheet 10 of the light source unit 2 arranged on a displaceable stage, and in this state, for each stage While moving the light source unit 2 in each of the x direction and the y direction, the front luminance was measured every 5 mm in each of the x direction and the y direction by the viewing angle characteristic measuring apparatus. From the measurement results, the maximum value, minimum value, average value, and luminance unevenness of the front luminance were calculated. Here, the maximum value of the front luminance is the highest luminance during the measurement.
- EZContrast 80 manufactured by ELDIM
- the minimum value of the front luminance is the lowest luminance during the measurement.
- the average value is an average value of the measured front luminance.
- the luminance unevenness was calculated by the following formula (2).
- the standard of the upper limit value of the luminance unevenness that makes the lamp image invisible is about 2.5%.
- Luminance unevenness ((Maximum value of front luminance) ⁇ (Minimum value of front luminance)) / (Average value of front luminance) (2) Further, by visually observing the obtained light source unit 2, it was confirmed whether or not a rainbow color pattern was visually recognized.
- Example 2 Except that the pitch of the microlens array 21 was 5 ⁇ m and the diameter of the microlens 22 was 4.8 ⁇ m, the light source unit 2 was produced in the same manner as in Example 1 above, and luminance unevenness measurement and visual inspection were performed. In addition, the occupation ratio of the microlens 22 in the present example was 80.3%.
- Example 3 Except that the pitch of the microlens array 21 was 3 ⁇ m and the diameter of the microlens 22 was 2.8 ⁇ m, the light source unit 2 was produced in the same manner as in Example 1 above, and luminance unevenness measurement and visual inspection were performed. In addition, the occupation ratio of the microlens 22 in the present example was 79%.
- Example 4 Except that the pitch of the microlens array 21 was 1.8 ⁇ m and the diameter of the microlens 22 was 1.7 ⁇ m, the light source unit 2 was produced in the same manner as in Example 1 above, and luminance unevenness measurement and visual inspection were performed. . In addition, the occupation ratio of the microlens 22 in the present example was 80.9%.
- Example 5 Except that the pitch of the microlens array 21 was 1.5 ⁇ m and the diameter of the microlens 22 was 1.4 ⁇ m, the light source unit 2 was produced in the same manner as in Example 1 above, and luminance unevenness measurement and visual inspection were performed. . In addition, the occupation ratio of the microlens 22 in the present example was 79%.
- Example 6 A light source unit 2 was produced in the same manner as in Example 1 except that the microlenses 22 were arranged in a square lattice pattern as shown in FIG. 13, and luminance unevenness measurement and visual inspection were performed.
- Example 7 Except that the microlenses 22 were arranged in a square lattice pattern as shown in FIG. 13, the light source unit 2 was prepared in the same manner as in Example 2 above, and the luminance unevenness was measured and visually inspected.
- Example 8 A light source unit 2 is produced in the same manner as in Example 1 except that a sheet having the microlens array 11 shown in FIGS. 2 and 3 is used as the light diffusion sheet 10, and luminance unevenness measurement and visual inspection are performed. It was.
- the microlens 12 has a substantially hemispherical shape with a diameter of 9.4 ⁇ m, and the pitch of the microlens array 11 is 9.9 ⁇ m.
- Example 9 Except that the pitch of the microlens array 21 was 5 ⁇ m and the diameter was 4.8 ⁇ m, the light source unit 2 was produced in the same manner as in Example 8 above, and measurement of luminance unevenness and visual inspection were performed.
- Example 10 Except that the pitch of the microlens array 21 was 3 ⁇ m and the diameter was 2.8 ⁇ m, the light source unit 2 was produced in the same manner as in Example 8, and the luminance unevenness was measured and visually inspected.
- the light source device 30 has the linear light source 34 shown in FIG. 14, and the light source unit 2 is produced in the same manner as in Example 1 except that the dimensions of the optical sheet 20 are 30 cm long and 40 cm wide. Unevenness measurement and visual inspection were performed. Specifically, in this example, a liquid crystal television (product name: AQUAS LC-20S1) manufactured by Sharp Corporation was disassembled, the backlight was taken out, and the backlight was used as the light source device 30. The dimensions of the light source device 30 were 395 mm in width, 285 mm in length, and 17.8 mm in thickness.
- Example 12 Except that the pitch of the microlens array 21 was 5 ⁇ m and the diameter was 4.8 ⁇ m, the light source unit 2 was produced in the same manner as in Example 11 above, and luminance unevenness measurement and visual inspection were performed.
- Example 13 The light source unit 2 was prepared in the same manner as in Example 2 except that the pitch of the microlens array 21 was 5 ⁇ m, the diameter was 4.4 ⁇ m, and the occupation ratio of the microlens 22 was 70%. A visual inspection was performed.
- Example 14 The light source unit 2 was prepared in the same manner as in Example 2 except that the pitch of the microlens array 21 was 5 ⁇ m, the diameter was 4.1 ⁇ m, and the occupation ratio of the microlens 22 was 60%. A visual inspection was performed.
- Example 15 The light source unit 2 was prepared in the same manner as in Example 2 except that the pitch of the microlens array 21 was 5 ⁇ m, the diameter was 3.7 ⁇ m, and the occupation ratio of the microlens 22 was 50%. A visual inspection was performed.
- Example 1 Comparative Example 1 Except that the microlens array pitch was 21.2 ⁇ m and the microlens diameter was 20 ⁇ m, the light source unit 2 was prepared in the same manner as in Example 1 above, and luminance unevenness measurement and visual inspection were performed.
- Tables 1 and 2 below show the measurement results and inspection results of Examples 1 to 15 and Comparative Examples 1 to 3.
- the pitch of the microlens array 21 is preferably 5 ⁇ m or less, and more preferably 3 ⁇ m or less.
- Examples 8 to 10 in which the light diffusion sheet 10 having the microlens array 11 was used higher average luminance was obtained than in Examples 1 to 3 in which the light diffusion sheet 10 was a bead type. From this result, it can be seen that the light diffusion sheet 10 preferably has the microlens array 11.
- Example 11 and Example 12 using a linear light source as the light source low luminance unevenness was measured as in Example 1 and Example 2. From this result, it can be seen that the optical element 3 according to the present invention can be suitably used not only for a point light source but also for a linear light source.
- Example 2 As shown in Example 2 and Examples 13 to 15, it can be seen that the occupation ratio of the microlens 22 increases and the luminance unevenness decreases. It can be seen that the luminance unevenness can be particularly reduced by setting the occupation ratio of the microlens 22 to 80% or more.
- Example 16 Except for the conditions shown in Table 3 below, the optical sheet 20 and the light source unit 2 were prepared in the same manner as in Example 1 above, and the average luminance and luminance unevenness were measured in the same manner as in Example 1 above. A visual test was conducted. Furthermore, the transmittance in the normal direction (0 degree) when a light beam having a wavelength of 550 nm is incident on the optical sheet 20 by a combination of a beam light source and a goniophotometer (manufactured by Sigma Koki Co., Ltd., polarization analyzer), and The transmittance of the first-order diffracted light was measured. The results are shown in Table 3 below.
- Example 17 Except for the conditions shown in Table 3 below, the optical sheet 20 and the light source unit 2 were produced in the same manner as in Example 16, and the average luminance, luminance unevenness, and normal direction (0 degrees) were obtained in the same manner as in Example 16. In addition to measuring the transmittance and the transmittance of the first-order diffracted light (first-order diffracted light transmittance), a visual test of the rainbow pattern was performed. The results are shown in Table 3 below.
- Example 18 Except for the conditions shown in Table 3 below, the optical sheet 20 and the light source unit 2 were produced in the same manner as in Example 16, and the average luminance, luminance unevenness, and normal direction (0 degrees) were obtained in the same manner as in Example 16. In addition to measuring the transmittance and the transmittance of the first-order diffracted light (first-order diffracted light transmittance), a visual test of the rainbow pattern was performed. The results are shown in Table 3 below.
- Example 19 Except for the conditions shown in Table 3 below, the optical sheet 20 and the light source unit 2 were produced in the same manner as in Example 16, and the average luminance, luminance unevenness, and normal direction (0 degrees) were obtained in the same manner as in Example 16. In addition to measuring the transmittance and the transmittance of the first-order diffracted light (first-order diffracted light transmittance), a visual test of the rainbow pattern was performed. The results are shown in Table 3 below.
- Example 20 Except for the conditions shown in Table 3 below, the optical sheet 20 and the light source unit 2 were produced in the same manner as in Example 16, and the average luminance, luminance unevenness, and normal direction (0 degrees) were obtained in the same manner as in Example 16. In addition to measuring the transmittance and the transmittance of the first-order diffracted light (first-order diffracted light transmittance), a visual test of the rainbow pattern was performed. The results are shown in Table 3 below.
- Example 21 Except for the conditions shown in Table 3 below, the optical sheet 20 and the light source unit 2 were produced in the same manner as in Example 16, and the average luminance, luminance unevenness, and normal direction (0 degrees) were obtained in the same manner as in Example 16. In addition to measuring the transmittance and the transmittance of the first-order diffracted light (first-order diffracted light transmittance), a visual test of the rainbow pattern was performed. The results are shown in Table 3 below.
- Example 22 Except for the conditions shown in Table 3 below, the optical sheet 20 and the light source unit 2 were produced in the same manner as in Example 16, and the average luminance, luminance unevenness, and normal direction (0 degrees) were obtained in the same manner as in Example 16. In addition to measuring the transmittance and the transmittance of the first-order diffracted light (first-order diffracted light transmittance), a visual test of the rainbow pattern was performed. The results are shown in Table 3 below.
- Example 23 Except for the conditions shown in Table 3 below, the optical sheet 20 and the light source unit 2 were produced in the same manner as in Example 16, and the average luminance, luminance unevenness, and normal direction (0 degrees) were obtained in the same manner as in Example 16. In addition to measuring the transmittance and the transmittance of the first-order diffracted light (first-order diffracted light transmittance), a visual test of the rainbow pattern was performed. The results are shown in Table 3 below.
- the 0-degree transmittance is less than 30%. Or less than 2.5% of the non-uniformity of brightness compared to Examples 16, 18, 21, 23 in which the first-order diffracted light transmittance is less than 2%, and the average brightness is 6200 cd / m 2 or more. It was particularly high. From this result, it can be seen that when the 0 degree transmittance is 30% or less and the first-order diffracted light transmittance is 2% or more, both high front luminance and small luminance unevenness can be achieved.
- the point A in FIG. 0, 0.875), point B (1.0, 0.625), point C (1.5, 0.375), point D (2.0, 0.375), point E (2.0, 0.625) and the point F (1.5, 0.875) are preferably located within the region X1 formed by connecting the straight lines in this order.
- the pitch of the microlens array 21 and the aspect ratio of the microlens 22 are point G (1.0, 0.75), point H (1.5, 0.5), and point I (2) in FIG. 0.0, 0.5) and the point J (1.5, 0.75) are more preferably located within the region X2 formed by connecting the straight lines in this order.
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Abstract
Description
本発明によれば、光学シートが、ピッチが10μm未満のマイクロレンズアレイを有し、且つ入射光を屈折させることによって拡散させる光拡散シートが光学シートの光出射面側に配置されているため、光の取り出し効率を高くすることができるとともに、点状光源がマトリクス状に配置されたバックライトの直交する2つの方向における輝度むらをも解消させることができる。
2…光源ユニット
3…光学素子
10…光拡散シート
10a…光入射面
10b…光出射面
11…マイクロレンズアレイ
12…マイクロレンズ
20…光学シート
20a…光入射面
20b…光出射面
21…マイクロレンズアレイ
22…マイクロレンズ
25…マイクロレンズ
30…光源デバイス
30a…光出射面
31…ケーシング
31a…凹部
32…点状光源
33…透光基板
34…線状光源
40…液晶表示セル
41a…偏光板
41b…偏光板
但し、
P:マイクロレンズアレイ21のピッチ、
n:自然数、
λ:マイクロレンズアレイ21に入射する光線の波長、
である。
上記実施形態では、マイクロレンズ22が所謂正三角形格子配列されている例について説明した。但し、本発明において、マイクロレンズ22の配列は所謂正三角形格子配列に限定されない。マイクロレンズ22は、図13に示すように、相互に直交するx方向及びy方向のそれぞれにおいて規則的且つ周期的に配列されていてもよい。図13に示すように、相互に直交するx方向及びy方向のそれぞれにおいて規則的且つ周期的にマイクロレンズ22を配列した場合、x方向とy方向とにおいてマイクロレンズアレイ21のピッチを略同一にすることができる。このため、x方向における光学シート20の光拡散性能と、y方向における光学シート20の光拡散性能とを略同一にすることができる。
上記実施形態では、光源デバイス30が複数の点状光源32を有する例について説明した。但し、本発明において、光源デバイス30に設ける光源の種類は点状光源に限定されない。例えば、光源デバイス30は、例えば、図14及び図15に示すように、並列に配列された複数の線状光源34を有するものであってもよい。線状光源34の種類は特に限定されない。線状光源34は、例えば、冷陰極蛍光ランプ(Cold Cathode Fluorescent Lamp:CCFL)などであってもよい。
上記実施形態では、光学シート20の光出射面20bに、凸状に形成された複数のマイクロレンズ22を有するマイクロレンズアレイ21が形成されている例について説明した。但し、本発明において、マイクロレンズ22は、凹状であってもよい。また、マイクロレンズアレイ21は、光学シート20の光入射面20aに形成されていてもよい。マイクロレンズアレイ21は、光学シート20の光出射面20bと光入射面20aとの両方に形成されていてもよい。
光学シート20及び光拡散シート10のうちの少なくとも一方が複数配置されていてもよい。すなわち、光学シート20と光拡散シート10とのそれぞれの配置枚数は1枚に限定されない。
まず、縦10cm、横10cm、厚さ200μmのポリカーボネートフィルム(帝人化成(株)製 品名:パンライト1225LL)をロールプレスすることによって、直径9.4μmの略半球状のマイクロレンズ22が図4に示すピッチ9.9μmの正三角形格子パターンで形成された光学シート20を得た。マイクロレンズ22の占有率は、81.8%であった。
さらに、得られた光源ユニット2を目視することによって、虹色模様が視認されるか否かを確認した。
マイクロレンズアレイ21のピッチを5μm、マイクロレンズ22の直径を4.8μmとしたこと以外は、上記実施例1と同様に光源ユニット2を作製し、輝度むらの測定及び視認検査を行った。なお、本実施例におけるマイクロレンズ22の占有率は、80.3%であった。
マイクロレンズアレイ21のピッチを3μm、マイクロレンズ22の直径を2.8μmとしたこと以外は、上記実施例1と同様に光源ユニット2を作製し、輝度むらの測定及び視認検査を行った。なお、本実施例におけるマイクロレンズ22の占有率は、79%であった。
マイクロレンズアレイ21のピッチを1.8μm、マイクロレンズ22の直径を1.7μmとしたこと以外は、上記実施例1と同様に光源ユニット2を作製し、輝度むらの測定及び視認検査を行った。なお、本実施例におけるマイクロレンズ22の占有率は、80.9%であった。
マイクロレンズアレイ21のピッチを1.5μm、マイクロレンズ22の直径を1.4μmとしたこと以外は、上記実施例1と同様に光源ユニット2を作製し、輝度むらの測定及び視認検査を行った。なお、本実施例におけるマイクロレンズ22の占有率は、79%であった。
マイクロレンズ22を図13に示すように正方形格子パターンに配列させたこと以外は、上記実施例1と同様に光源ユニット2を作製し、輝度むらの測定及び視認検査を行った。
マイクロレンズ22を図13に示すように正方形格子パターンに配列させたこと以外は、上記実施例2と同様に光源ユニット2を作製し、輝度むらの測定及び視認検査を行った。
光拡散シート10として、図2及び図3に示すマイクロレンズアレイ11を有するシートを用いたこと以外は、上記実施例1と同様に光源ユニット2を作製し、輝度むらの測定及び視認検査を行った。本実施例では、マイクロレンズ12を直径9.4μmの略半球状とし、マイクロレンズアレイ11のピッチを9.9μmとした。
マイクロレンズアレイ21のピッチを5μm、直径を4.8μmとしたこと以外は、上記実施例8と同様に光源ユニット2を作製し、輝度むらの測定及び視認検査を行った。
マイクロレンズアレイ21のピッチを3μm、直径を2.8μmとしたこと以外は、上記実施例8と同様に光源ユニット2を作製し、輝度むらの測定及び視認検査を行った。
光源デバイス30を、図14に示す線状光源34を有するものとし、光学シート20の寸法を縦30cm、横40cmとしたこと以外は、上記実施例1と同様に光源ユニット2を作製し、輝度むらの測定及び視認検査を行った。具体的に、本実施例では、シャープ株式会社製の液晶テレビ(品名:AQUOS LC-20S1)を分解して、バックライトを取り出し、そのバックライトを光源デバイス30とした。光源デバイス30の寸法は、横395mm、縦285mm、厚さ17.8mmであった。
マイクロレンズアレイ21のピッチを5μm、直径を4.8μmとしたこと以外は、上記実施例11と同様に光源ユニット2を作製し、輝度むらの測定及び視認検査を行った。
マイクロレンズアレイ21のピッチを5μm、直径を4.4μmとして、マイクロレンズ22の占有率を70%にしたこと以外は、上記実施例2と同様に光源ユニット2を作製し、輝度むらの測定及び視認検査を行った。
マイクロレンズアレイ21のピッチを5μm、直径を4.1μmとして、マイクロレンズ22の占有率を60%にしたこと以外は、上記実施例2と同様に光源ユニット2を作製し、輝度むらの測定及び視認検査を行った。
マイクロレンズアレイ21のピッチを5μm、直径を3.7μmとして、マイクロレンズ22の占有率を50%にしたこと以外は、上記実施例2と同様に光源ユニット2を作製し、輝度むらの測定及び視認検査を行った。
マイクロレンズアレイのピッチを21.2μm、マイクロレンズの直径を20μmとしたこと以外は、上記実施例1と同様に光源ユニット2を作製し、輝度むらの測定及び視認検査を行った。
光拡散シート10のみを配置し、光学シート20を配置しなかったこと以外は、上記実施例1と同様に光源ユニットを作製し、輝度むらの測定及び視認検査を行った。
光学シート20のみを配置し、光拡散シート10を配置しなかったこと以外は、上記実施例1と同様に光源ユニットを作製し、輝度むらの測定及び視認検査を行った。
下記表3に示す条件としたこと以外は、上記実施例1と同様に光学シート20、光源ユニット2を作製し、上記実施例1と同様に平均輝度及び輝度むらを測定すると共に、虹色模様の視認テストを行った。さらに、ビーム光源とゴニオフォトメータの組み合わせ(シグマ光機社製、偏光解析装置)により、光学シート20に波長550nmの光ビームを入射させたときの法線方向(0度)における透過率、及び1次回折光の透過率を測定した。結果を下記の表3に示す。
下記表3に示す条件としたこと以外は、上記実施例16と同様に光学シート20、光源ユニット2を作製し、上記実施例16と同様に平均輝度、輝度むら、法線方向(0度)における透過率、及び1次回折光の透過率(1次回折光透過率)を測定すると共に、虹色模様の視認テストを行った。結果を下記の表3に示す。
下記表3に示す条件としたこと以外は、上記実施例16と同様に光学シート20、光源ユニット2を作製し、上記実施例16と同様に平均輝度、輝度むら、法線方向(0度)における透過率、及び1次回折光の透過率(1次回折光透過率)を測定すると共に、虹色模様の視認テストを行った。結果を下記の表3に示す。
下記表3に示す条件としたこと以外は、上記実施例16と同様に光学シート20、光源ユニット2を作製し、上記実施例16と同様に平均輝度、輝度むら、法線方向(0度)における透過率、及び1次回折光の透過率(1次回折光透過率)を測定すると共に、虹色模様の視認テストを行った。結果を下記の表3に示す。
下記表3に示す条件としたこと以外は、上記実施例16と同様に光学シート20、光源ユニット2を作製し、上記実施例16と同様に平均輝度、輝度むら、法線方向(0度)における透過率、及び1次回折光の透過率(1次回折光透過率)を測定すると共に、虹色模様の視認テストを行った。結果を下記の表3に示す。
下記表3に示す条件としたこと以外は、上記実施例16と同様に光学シート20、光源ユニット2を作製し、上記実施例16と同様に平均輝度、輝度むら、法線方向(0度)における透過率、及び1次回折光の透過率(1次回折光透過率)を測定すると共に、虹色模様の視認テストを行った。結果を下記の表3に示す。
下記表3に示す条件としたこと以外は、上記実施例16と同様に光学シート20、光源ユニット2を作製し、上記実施例16と同様に平均輝度、輝度むら、法線方向(0度)における透過率、及び1次回折光の透過率(1次回折光透過率)を測定すると共に、虹色模様の視認テストを行った。結果を下記の表3に示す。
下記表3に示す条件としたこと以外は、上記実施例16と同様に光学シート20、光源ユニット2を作製し、上記実施例16と同様に平均輝度、輝度むら、法線方向(0度)における透過率、及び1次回折光の透過率(1次回折光透過率)を測定すると共に、虹色模様の視認テストを行った。結果を下記の表3に示す。
Claims (15)
- 光入射面と、光出射面とを有する光学シートと、
前記光学シートの前記光出射面側に配置され、入射光を屈折させることによって拡散させる光拡散シートと、
を備える光学素子であって、
前記光入射面及び前記光出射面の少なくとも一方に、マイクロレンズアレイが形成されており、
前記マイクロレンズアレイは、凸状または凹状に形成された複数のマイクロレンズが10μm未満のピッチで周期的且つマトリクス状に配列されている、
光学素子。 - 前記マイクロレンズは、凸状に形成されており、
前記マイクロレンズアレイは、前記光出射面に形成されている、請求項1に記載の光学素子。 - 前記マイクロレンズアレイのピッチは5μm以下である、請求項1または2に記載の光学素子。
- 前記マイクロレンズアレイのピッチは3μm以下である、請求項1~3のいずれか一項に記載の光学素子。
- 前記光拡散シートは、複数のマイクロレンズが10μm以上のピッチで配列されたマイクロレンズアレイを有する、請求項1~4のいずれか一項に記載の光学素子。
- 前記光学シートのマイクロレンズは、平面視略円形であり、
平面視における前記光学シートのマイクロレンズの直径は、前記光学シートのマイクロレンズアレイのピッチの50%以上である、請求項1~5のいずれか一項に記載の光学素子。 - 平面視における前記光学シートのマイクロレンズの直径は、前記光学シートのマイクロレンズアレイのピッチの80%以上である、請求項6に記載の光学素子。
- 前記光入射面と前記光出射面とのうちの前記マイクロレンズアレイが形成されている側の面における前記マイクロレンズの占有率が80%以上であり、
前記マイクロレンズアレイのピッチ(μm)をX軸とし、前記マイクロレンズの高さを前記マイクロレンズの直径で除算して得られる前記マイクロレンズのアスペクト比をY軸とする図17に示す座標系において、(前記マイクロレンズアレイのピッチ、前記マイクロレンズのアスペクト比)が、点A(1.0,0.875)、点B(1.0,0.625)、点C(1.5,0.375)、点D(2.0,0.375)、点E(2.0,0.625)及び点F(1.5,0.875)をこの順に直線で結んで形成される領域内に位置する、請求項1~7のいずれか一項に記載の光学素子。 - 前記マイクロレンズアレイのピッチ(μm)をX軸とし、前記マイクロレンズの高さを前記マイクロレンズの直径で除算して得られる前記マイクロレンズのアスペクト比をY軸とする図17に示す座標系において、(前記マイクロレンズアレイのピッチ、前記マイクロレンズのアスペクト比)が点G(1.0,0.75)、点H(1.5,0.5)、点I(2.0,0.5)及び点J(1.5,0.75)をこの順に直線で結んで形成される領域内に位置する、請求項8に記載の光学素子。
- 前記光学シートのマイクロレンズアレイは、前記光学シートが拡散角0度における透過率よりも高い透過率を有する透過光のピークを0度以外の拡散角において有するように形成されている、請求項1~9のいずれか一項に記載の光学素子。
- 前記光学シートの複数のマイクロレンズは、第1の方向と、前記第1の方向と直交する第2の方向との両方において規則的且つ周期的に配列されている、請求項1~10のいずれか一項に記載の光学素子。
- 前記光学シートの複数のマイクロレンズは、平面視において、隣接するマイクロレンズの中心を結んでなる図形が正三角形となるように配列されている、請求項1~10のいずれか一項に記載の光学素子。
- 請求項1~12のいずれか一項に記載の光学素子と、
前記光学素子の光入射面側に配置され、前記光入射面に向けて光を出射させる光源デバイスと、
を備える光源ユニット。 - 前記光源デバイスは、複数の点状光源を有する、請求項13に記載の光源ユニット。
- 請求項13または14に記載の光源ユニットと、
前記光拡散シートの光出射面側に配置された液晶表示セルと、
を備える液晶表示装置。
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CN103003724A (zh) * | 2010-07-15 | 2013-03-27 | Lg化学株式会社 | 具有改进的光学性能的光学膜及包含该光学膜的背光单元 |
JP2013057736A (ja) * | 2011-09-07 | 2013-03-28 | Mitsubishi Rayon Co Ltd | 光学フィルム及びそれを用いた光学装置 |
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KR101279483B1 (ko) * | 2011-06-29 | 2013-07-05 | 엘지이노텍 주식회사 | 광학플레이트 및 이를 이용한 조명부재 |
JP5851810B2 (ja) * | 2011-11-25 | 2016-02-03 | 浜松ホトニクス株式会社 | 基準光源 |
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CN110208984B (zh) * | 2019-05-28 | 2020-12-25 | 惠州市华星光电技术有限公司 | 背光结构和显示面板 |
CN114024207A (zh) * | 2020-07-17 | 2022-02-08 | 宁波舜宇车载光学技术有限公司 | 发射端及制备方法 |
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