WO2015151255A1 - Light guide plate, and device using light guide plate - Google Patents

Light guide plate, and device using light guide plate Download PDF

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Publication number
WO2015151255A1
WO2015151255A1 PCT/JP2014/059823 JP2014059823W WO2015151255A1 WO 2015151255 A1 WO2015151255 A1 WO 2015151255A1 JP 2014059823 W JP2014059823 W JP 2014059823W WO 2015151255 A1 WO2015151255 A1 WO 2015151255A1
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Prior art keywords
light
guide plate
light guide
grating
incident
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PCT/JP2014/059823
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French (fr)
Japanese (ja)
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島野　健
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日立マクセル株式会社
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Priority to PCT/JP2014/059823 priority Critical patent/WO2015151255A1/en
Publication of WO2015151255A1 publication Critical patent/WO2015151255A1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/0035—Means for improving the coupling-out of light from the light guide provided on the surface of the light guide or in the bulk of it
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/005—Means for improving the coupling-out of light from the light guide provided by one optical element, or plurality thereof, placed on the light output side of the light guide
    • G02B6/0055—Reflecting element, sheet or layer

Definitions

  • the present invention relates to a color-forming light guide plate used for design illumination and the like, and an apparatus using the same.
  • the existing light guide plate is used for the backlight of the liquid crystal display, there is no wavelength selectivity regarding the emitted light. Therefore, the emitted light from such a light guide plate is generally the same color as the illumination light source. Therefore, the following techniques have been proposed as techniques for examining the wavelength selectivity of the emitted light in the light guide plate.
  • the light guide plate and a multilayer filter formed on at least one of the two opposing surfaces of the light guide plate and alternately laminated with a high refractive index dielectric layer and a low refractive index dielectric layer are provided.
  • an optical element see Patent Document 1 is proposed in which the film thickness is continuously changed within the at least one surface.
  • the emitted light can be colored, but energy loss of the wavelength absorbed by the color filter occurs.
  • the wavelength selectivity is maintained over a wide range of incident angles that are greater than the critical angle of total reflection due to the angle selectivity characteristic of the reflective volume hologram.
  • the degree of freedom in design is limited and the application range tends to be narrow.
  • an object of the present invention is to provide a technology of a light guide plate that can be applied to a light source having a wide light emission angle distribution and that is low in production cost and light amount loss accompanying wavelength selection.
  • the configuration described in the claims is adopted.
  • the present application includes a plurality of means for solving the above-mentioned problems.
  • the light guide plate includes diffraction gratings on the upper surface and the lower surface of the transparent substrate.
  • an illumination device using the light guide plate of the present invention includes a light guide plate having diffraction gratings on the upper surface and the lower surface of a transparent substrate, a light source that makes light incident on a predetermined end surface of the light guide plate, and a drive device for the light source. It is characterized by having.
  • the apparatus of the present invention includes a lighting device including a light guide plate having diffraction gratings on the upper surface and the lower surface of the transparent substrate, a light source that makes light incident on a predetermined end surface of the light guide plate, and a drive device for the light source. It is characterized by doing.
  • a light guide plate that can be applied to a light source having a wide light emission angle distribution and that has a small amount of light loss due to manufacturing cost and wavelength selection.
  • FIG. 1 is a diagram illustrating a configuration example of a light guide plate 100 in the first embodiment.
  • the light guide plate 100 shown in FIG. 1 is applicable to a light source having a wide light emission angle distribution, and is a light guide plate with little manufacturing cost and less light loss due to wavelength selection.
  • white light 103 incident light
  • a white LED light source 102 is incident on a transparent light guide plate substrate 101 included in the light guide plate 100.
  • the light incident surface 1013 of the light guide plate substrate 101 is obliquely cut away from the perpendicular 1014, and the light beam having the highest intensity of the incident white light 103 has a critical angle of total reflection in the light guide plate substrate 101. It is set to have a predetermined incident angle ⁇ 0 which is about the middle of 90 °.
  • the light guide plate substrate 101 includes lattice regions 104, 105, and 106 in which lattices having different lattice depths and lattice pitches are formed.
  • the grating regions 104, 105, and 106 are regions that emit light having different wavelengths, and the white light 103 incident from the incident surface 1013 is light having a wavelength for each region in the order in which the lattice regions 104 to 106 are arranged. Is continuously transmitted.
  • the inclination directions of the grating surfaces 1041 and 1042 are parallel to each other, and the grating pitch p and the grating depth d are made equal.
  • the inclination directions of the grating surfaces 1051 and 1052 are parallel to each other, and the grating pitch p and the grating depth d are respectively set. equal.
  • the diffraction angles by the blazed diffraction grating become ⁇ 1 , ⁇ 2 , and ⁇ 3 , they are diffracted in the opposite direction by the blazed diffraction grating facing the upper surface 1011 and the lower surface 1012.
  • the original incident angle ⁇ 0 is restored, and basically the diffracted light can be stably propagated through the light guide plate 10.
  • a blazed diffraction grating can obtain diffracted light with a diffraction efficiency of 100% in principle at an incident angle and wavelength satisfying the blaze condition if the reflectance at the interface is 100% due to total reflection or the like. Can do. Under such conditions, light can propagate with 100% efficiency in the light guide plate as described above with the blazed grating facing each other.
  • unit lattice regions 120 and 122 in which lattice grooves are continuously disposed are intermittently disposed with the planar regions 121 and 13 interposed therebetween. Further, the interval between the unit cell regions 120 and 122, that is, the planar regions 121 and 123 are gradually narrowed in the light guide direction.
  • This configuration is illustrated only for the lattice region 104 in FIG. 1, but the same applies to the other lattice regions 105 and 106.
  • the number of lattices in the rightmost unit lattice region 1201 in the drawing is larger than the number of lattices in the previous unit lattice regions 1202 and 1203.
  • the light is basically designed to be emitted only from the unit lattice region 120 on the upper surface 1011 of the light guide plate 100. Since the local emission efficiency is constant, the shorter the light guide distance is, the longer the lattice is. The emitted light intensity is increased. However, in the light guide plate 100, it is ideal that the output light intensity is equal regardless of the light guide distance. Thus, the unit cell region is made intermittent in this way, and the average output light intensity is made uniform by changing the interval. I am trying.
  • Such uniforming of the emitted light intensity may be achieved by gradually increasing the effective area where the grating is formed in the light guide direction of the light guide plate 100 as the distance from the incident surface 1013 increases. Therefore, instead of changing the interval between the unit lattice regions 120, 122 having the same number of lattices, that is, the size of the planar regions 121, 123, the interval between the unit lattice regions 120, 122 is the same, and each unit lattice region 120, The number of grids 122 may be gradually increased as the distance from the incident surface 1013 increases. However, in order to obtain the light diffraction effect, a certain number of continuous lattices of several tens are necessary (in the light guide plate 100 in FIG. 1, the number of lattices is smaller than the actual number for simplification. is doing).
  • the white incident light 103 incident on the incident surface 1013 of the light guide plate 100 from the LED light source 102 has light of three wavelength components of ⁇ 1, ⁇ 2, and ⁇ 3.
  • 106 are designed so that the wavelength regions of the light emitted from the upper surface 1011 are different by changing the groove shape of the grating. Since light in the wavelength band near ⁇ 1 is mainly emitted in the grating region 104, the remaining light in the wavelength bands of ⁇ 2 and ⁇ 3 is dominant in the light beam 113 incident on the grating region 105. In addition, in the grating region 105, light of ⁇ 2 is mainly emitted. Similarly, in the light beam 114 incident on the grating region 106, the remaining light in the wavelength band centering on ⁇ 3 is dominant, and in the grating region 106, light having a wavelength of ⁇ 3 is mainly emitted.
  • the diffracted light traveling from the unit cell region 122 on the lower surface 1012 toward the upper surface 1011 is incident again on the corresponding unit cell region 120 on the upper surface 1011, and the unit cell regions 120 on the upper surface 1011 and the lower surface 1012.
  • the boundary position 122 is shifted.
  • the diffraction angle from the blazed diffraction grating of the upper surface 1011 is ⁇ 0. Will not return. However, if it is a diffraction angle at which light can be guided stably, light guide is continued at that angle.
  • the light emitted from the upper surface 1011 of the light guide plate 100 causes the diffraction efficiency on the transmission side of the upper surface 1011 to be higher than other wavelengths at a specific wavelength due to the wavelength dependence of the diffraction angle of the blazed diffraction grating.
  • the condition is basically that no outgoing light is generated at a nearby wavelength, and thus the outgoing angle of the outgoing light is an outgoing angle with a large surface grazing of the light guide plate substrate 101. Therefore, in order for the observer to recognize the emitted light directly facing the surface of the light guide plate, a diffusion plate 115 is disposed on the emission surface with an air gap 118 interposed therebetween.
  • a support member 116 is disposed between the upper surface 1011 and the diffusion plate 115 to the extent that light emission is not hindered.
  • the lower surface 1012 is coated with a metal film 117 in order to reduce the light amount loss due to the transmitted light on the lower surface 1012.
  • FIG. 2 shows a blue light having a wavelength of 0.45 ⁇ m at an incident angle of 50 ° on an opposed blazed diffraction grating (corresponding to a unit grating region) having a medium refractive index of 1.5, a pitch of 2.4 ⁇ m, and a grating depth of 0.32 ⁇ m. It is a light ray figure of diffracted light at the time of making enter.
  • the light beam angle it is shown that from the second-order diffracted light to the 11th-order diffracted light can be emitted from the upper surface 1011 of the light guide plate 100, and the second-order diffracted light or less cannot be emitted and is totally reflected. Further, the ⁇ 1st order diffracted light of the first order diffracted light reflected by the upper surface 1011 is incident on the lower surface 1012 again at the same incident angle of 50 ° as the original incident light. That is, this becomes stable propagation light.
  • FIG. 3 shows the efficiency of each diffracted light beam emitted from the upper surface 1011 in FIG. 2 described above.
  • the second-order diffracted light is emitted from the upper surface 1011 with an efficiency of about 45%, but it can be seen that the efficiency of other orders is small.
  • FIG. 4 shows the efficiency of each order of light reflected by the upper surface 1011.
  • the first-order diffracted light is reflected into the light guide plate substrate 101 with a diffraction efficiency of 40%.
  • FIG. 5 shows a calculation result of diffraction efficiency in which the first-order diffracted light reflected from the upper surface 101 is diffracted by the blazed diffraction grating on the upper surface 101 when the intensity of the original incident light 103 is 1. It can be seen that the efficiency of ⁇ 1st order light that can be stably propagated is about 20%.
  • FIG. 6 is a ray diagram when red light having a wavelength of 0.65 ⁇ m is incident on the same grating at the same incident angle. It can be seen that the light rays that can be emitted from the upper surface 1011 are the second-order light to the seventh-order light, and the orders below the first-order diffracted light are also totally reflected in the light guide plate substrate 101.
  • FIG. 7 shows the efficiency of each order of diffracted light emitted from the upper surface 1011 in FIG. Like the blue light, the second-order diffracted light has the largest amount of light, but the efficiency is about 9%, which is much smaller than the blue light.
  • FIG. 8 shows each diffraction efficiency of the reflected light reflected from the upper surface 1011 in FIG. It can be seen that the first-order diffracted light is reflected into the light guide plate substrate 101 with an efficiency of about 80%.
  • FIG. 9 shows the diffraction efficiency when the first-order diffracted light reflected in FIG. 8 is diffracted by the diffraction grating on the upper surface 1011. It can be seen that while the efficiency is almost 80%, it is diffracted as ⁇ 1st order light and becomes propagating light at the same incident angle as the incident light 103.
  • FIG. 10 shows the top surface emission efficiency and propagation efficiency averaged over an angle range from 45 ° to 75 ° in the present embodiment. It can be seen from the horizontal axis of the graph of FIG. 10 that the blue light propagation efficiency corresponding to the short wavelength region is low and the emission efficiency is large.
  • FIG. 11 shows the light guide plate substrate 101 with a thickness of 3 mm and a structure in which diffraction regions are continuously formed (a structure that is not discrete and does not include the planar region 121) and is uniform from the amount of light emitted per propagation length. This is a logarithm of the light emission intensity per unit length with respect to the propagation distance when it is assumed that light is emitted. As shown in this graph, although the emission intensity of blue light is large at a propagation distance of 0, it can be seen that the intensity rapidly decreases as the propagation distance increases.
  • FIG. 12 shows the ratio of providing the diffraction grating region in the propagation distance in the light guide direction of the light guide plate 100 in order to improve the situation of FIG. 11 and make the light emission intensity uniform.
  • the ratio of the grating region is set to about 10% at the light incident position, and the ratio is set to gradually increase as the propagation distance increases from there.
  • the light emission intensity distribution in the light guide plate subjected to such measures is as shown in FIG.
  • FIG. 13 shows the emission intensity distribution in the light guide plate compensated based on the characteristics of FIG. 12 for each wavelength.
  • the vertical axis is not logarithmic but linear coordinates.
  • the intensity of blue light having a wavelength of 0.45 ⁇ m increases up to a propagation distance of about 50 mm.
  • FIG. 14 is a diagram showing an emission spectrum for each propagation distance in the compensated light guide plate. In this graph, it can be seen that blue light is dominant when the propagation distance is short, but red light becomes dominant as the propagation distance becomes longer.
  • FIG. 15 shows the top surface when blue light having a wavelength of 0.45 ⁇ m is incident on an opposing blazed diffraction grating having a medium refractive index of 1.5, a pitch of 2.4 ⁇ m, and a grating depth of 0.21 ⁇ m.
  • the efficiency of each diffracted light emitted from 1011 is shown. Although the diffracted light of the second order or higher is emitted, it can be seen that the efficiency is as small as 3% or less.
  • FIG. 16 shows the efficiency of each subsequent light reflected from the upper surface 1011.
  • the first-order diffracted light is reflected into the light guide plate substrate 101 with a diffraction efficiency of 80% or more.
  • FIG. 17 shows a calculation result of diffraction efficiency in which the first-order diffracted light reflected from the upper surface 1011 is diffracted by the blazed diffraction grating on the upper surface 1011 when the intensity of the original incident light 103 is 1.
  • the efficiency of ⁇ 1st order light that can be stably propagated is 80% or more.
  • FIG. 18 shows the efficiency of each order of diffracted light emitted from the upper surface 1011 when red light having a wavelength of 0.65 ⁇ m is incident on the same grating at the same incident angle.
  • red light having a wavelength of 0.65 ⁇ m is incident on the same grating at the same incident angle.
  • first-order diffracted light is emitted with an efficiency of 40% or more.
  • FIG. 19 shows the diffraction efficiency of the reflected light reflected from the upper surface 1011 shown in the graph of FIG. In this graph, it can be seen that the 0th order light and the 1st order diffracted light are reflected into the light guide plate substrate 101 with an efficiency of about 20%.
  • FIG. 20 shows the diffraction efficiency when the reflected first-order diffracted light shown in the graph of FIG. 19 is diffracted by the diffraction grating on the upper surface 1011.
  • the light is diffracted as ⁇ 1st order light with an efficiency of almost 20%, and becomes propagating light at the same incident angle as the incident light 103.
  • the graph of FIG. 19 since the 0th-order light has the same amount of light, the light propagating at the original incident angle is estimated to be about 40%.
  • FIG. 21 is a diagram showing the upper surface emission efficiency and propagation efficiency averaged over an angle range from an incident angle of 45 ° to 75 ° in the present example. Unlike the graph of FIG. 10, it can be seen that the propagation efficiency of red light is low and the amount of emitted light is large.
  • FIG. 22 shows a structure in which the light guide plate substrate 101 has a thickness of 3 mm and diffraction grating regions are continuously formed (a structure that is not discrete and does not include the planar region 121). It is the graph which showed the emitted light intensity per unit length with respect to propagation distance by the logarithm on the assumption that light is radiate
  • FIG. 23 shows the ratio of providing the diffraction grating region in the propagation distance in the light guide direction of the light guide plate 100 in order to improve the situation of FIG. 22 and make the light emission intensity uniform.
  • the ratio of the grating region is set to about 10% at the light incident position, and the ratio is set to gradually increase as the propagation distance increases from there.
  • the light emission intensity distribution in the light guide plate subjected to such measures is as shown in FIG.
  • FIG. 24 shows the emission intensity distribution in the light guide plate compensated based on the characteristics of FIG. 23 for each wavelength.
  • the vertical axis is not a logarithm but a linear coordinate. In the graph of FIG. 24, it can be seen that the intensity of red light having a wavelength of 0.6 to 0.65 ⁇ m is increased up to a propagation distance of about 80 mm.
  • FIG. 25 is a diagram showing an emission spectrum for each propagation distance. In this graph, it can be seen that red light is dominant when the propagation distance is short, but blue light becomes dominant as the propagation distance becomes longer.
  • FIG. 26 is a diagram illustrating a configuration example of an illumination device 200 using the light guide plate 100 in the present embodiment.
  • the conventional light guide plate 100 is often used as a monochromatic light source such as a backlight of a liquid crystal panel.
  • FIG. 26 shows an example in which the light guide plate 100 is mounted as the illumination device 200 that emits light of a plurality of colors.
  • the lighting device 200 includes a casing 210 made of resin or metal and having appropriate strength and heat dissipation efficiency, a glass panel 201 fitted in one surface of the casing 210, and the glass panel.
  • a light guide plate 100 that emits light via a diffuser plate 115, a white LED light source 102 that irradiates incident light on the end surface of the light guide plate 100, and the white LED light source 102 is driven and controlled.
  • An LED driving circuit 202 driving device such as a driver IC and a power source 205 that supplies electricity to the LED driving circuit 202 are configured.
  • FIG. 27 is a diagram illustrating a configuration example of the mobile terminal 300 using the lighting device 200 according to the present embodiment.
  • the example of the portable terminal 300 which incorporates the illuminating device 200 mentioned above and utilizes light emission for alerting a user or transmitting various information is shown.
  • the illumination device 200 incorporated in a part of the liquid crystal screen 301 emits uniform light in a wavelength selective manner regardless of the distance in the light guide direction.
  • the light guide plate 100 in the illumination device 200 emits a total of three colors of red, green, and blue.
  • the mounting example of such a light guide plate 100 is not limited to the above example.
  • the light guide plate 100 can be applied to display lamps (head lamps and tail lamps on the exterior of the vehicle body, turn indicators, interior lamps on the vehicle interior, and display instrument lamps) for various transport machines such as automobiles.
  • a light guide plate that can be applied to a light source having a wide light emission angle distribution and that has a small amount of light loss due to manufacturing cost and wavelength selection.
  • the diffraction grating is formed by unevenness of the transparent substrate.
  • the diffraction grating may be formed by discretely forming a plurality of grating regions formed by continuous groove-shaped gratings along the light guide direction.
  • the light emission intensity (outgoing light) can be made uniform along.
  • the interval between the plurality of discretely formed lattice regions may be gradually narrowed along the light guide direction.
  • the intensity of emitted light near the incident position on the light guide plate is appropriately suppressed, while the presence of the lattice area per unit light guide distance is suppressed.
  • an appropriate emitted light intensity can be obtained even at a position away from the incident position.
  • the number of lattices in each of the plurality of discretely formed lattice regions may be gradually increased along the light guide direction.
  • the intensity of the emitted light near the incident position on the light guide plate is appropriately suppressed, while by increasing the number of gratings in the grating region, the distance from the incident position is increased. An appropriate outgoing light intensity can be obtained even at the position.
  • the diffraction grating is a blazed diffraction grating, and the inclination directions of the grating surfaces are the same between the diffraction grating on the upper surface and the diffraction grating on the lower surface. It is.
  • the diffraction grating is a blazed diffraction grating, and one of the diffraction gratings on the upper surface and the lower surface has a large incident angle of light to be guided. It is preferable that the other lattice plane is inclined in the direction in which the incident angle of light to be guided is reduced.
  • the incident light incident from the end face of the light guide plate can continue to propagate between the grating surfaces of the diffraction gratings on the upper surface and the lower surface without disturbing the reflection angle.
  • the transmitted light can be transmitted to the light source, and the light amount loss can be further effectively reduced.
  • the grating surface inclined in the direction in which the incident angle of the light to be guided is reduced is assumed to be a metal film deposited. Is preferable.
  • the incident light incident from the end face of the light guide plate can continue to propagate between the grating surfaces of the diffraction gratings on the upper surface and the lower surface without disturbing the reflection angle.
  • a member having a diffusion surface is disposed on the outer surface of the light guide plate on the surface side close to the lattice surface inclined in the direction in which the incident angle of the light to be guided increases. If so, it is preferable.
  • a plurality of grating regions having different grating depths or grating pitches of the diffraction grating may be arranged along the light guide direction.
  • the angle of the end surface on which the light to be guided is incident with respect to the transparent substrate surface is an angle in a range where the propagation efficiency of the light guided in the light guide plate is equal to or greater than a predetermined value. If it is not vertical, it is preferable.

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Abstract

[Problem] To provide a light guide plate that can be used with a light source having a wide light emission angle distribution, and for which manufacturing cost and light amount loss accompanying wavelength selection are low. [Solution] A light guide plate (100) having a configuration in which a plurality of diffraction gratings (107-112) formed by irregularities in a transparent substrate (101) are discretely provided along the light-guide direction on the top surface (1011) and bottom surface (1012) of the transparent substrate (101).

Description

導光板及び導光板を用いた装置Light guide plate and device using light guide plate
　本発明は、意匠照明などに用いる発色型の導光板およびそれを用いた装置に関する。 The present invention relates to a color-forming light guide plate used for design illumination and the like, and an apparatus using the same.
　従来から存在する導光板は、液晶ディスプレイのバックライト用として採用されることからわかるように、出射光に関する波長選択性がない。そのため、こうした導光板からの出射光は照明光源と同じ色になるのが一般的である。そこで、導光板における出射光の波長選択性について検討した技術として、以下の技術が提案されている。 As is understood from the fact that the existing light guide plate is used for the backlight of the liquid crystal display, there is no wavelength selectivity regarding the emitted light. Therefore, the emitted light from such a light guide plate is generally the same color as the illumination light source. Therefore, the following techniques have been proposed as techniques for examining the wavelength selectivity of the emitted light in the light guide plate.
　すなわち、導光板と、同導光板の対向する２つの面の少なくとも一方に形成され、高屈折率誘電体層と低屈折率誘電体層を交互に積層した多層膜フィルタとを備え、同多層膜フィルタは、その膜厚が前記少なくとも一方の面内で連続的に変化するように形成されている光学素子（特許文献１参照）が提案されている。 Specifically, the light guide plate and a multilayer filter formed on at least one of the two opposing surfaces of the light guide plate and alternately laminated with a high refractive index dielectric layer and a low refractive index dielectric layer are provided. As the filter, an optical element (see Patent Document 1) is proposed in which the film thickness is continuously changed within the at least one surface.
　また、（Ａ）光が入射あるいは出射され、所望のブラッグ条件を満足する干渉縞が形成された回折領域、及び、（Ｂ）回折領域の縁部から延在し、回折領域から出射された光が入射し、あるいは又、回折領域に入射される光が出射され、所望のブラッグ条件を満足する干渉縞が形成されていない非回折領域、を有する反射型体積ホログラム回折格子から成る回折格子部材（特許文献２参照）なども提案されている。 Further, (A) a diffraction region where light is incident or emitted to form an interference fringe that satisfies a desired Bragg condition, and (B) light that extends from the edge of the diffraction region and is emitted from the diffraction region. Or a diffraction grating member composed of a reflective volume hologram diffraction grating having a non-diffractive area in which interference fringes satisfying a desired Bragg condition are not formed. Patent Document 2) is also proposed.
特開２００２－７２０１０号公報Japanese Patent Laid-Open No. 2002-72010 特開２００８－２０７７０号公報JP 2008-20770 A
　一方、従来型の導光板に特定波長の光を吸収するカラーフィルタを設置すれば、出射光を色づかせることはできるが、カラーフィルタで吸収される波長のエネルギーロスが生じる。 On the other hand, if a color filter that absorbs light of a specific wavelength is installed on a conventional light guide plate, the emitted light can be colored, but energy loss of the wavelength absorbed by the color filter occurs.
　他方、上述の従来技術の如く、多層膜の膜厚を連続的に変化させて出射光に波長選択性を生じさせる構成においては、基板材料と異なる少なくとも２種類の低屈折率材料と高屈折率材料が必要となり、材料コストが大きくなりやすい。また、多層膜の膜厚を連続的に変化させて成形を行うプロセスは、機器や工程時間等のコストが大きくなる問題点がある。 On the other hand, in the configuration in which the film thickness of the multilayer film is continuously changed to generate wavelength selectivity in the emitted light as in the above-described prior art, at least two kinds of low refractive index materials and high refractive indexes different from the substrate material are used. Material is required and the material cost tends to increase. Further, the process of forming by continuously changing the film thickness of the multilayer film has a problem that costs such as equipment and process time increase.
　また、反射型体積ホログラムを導光板に形成する技術においては、反射型体積ホログラムの持つ角度選択性の特性ゆえに、全反射の臨界角以上の広い範囲の入射角度に対して波長選択性を保つことができず、設計上の自由度が制限され、適用範囲が狭くなりやすいという問題点がある。 In addition, in the technology of forming a reflective volume hologram on the light guide plate, the wavelength selectivity is maintained over a wide range of incident angles that are greater than the critical angle of total reflection due to the angle selectivity characteristic of the reflective volume hologram. However, there is a problem that the degree of freedom in design is limited and the application range tends to be narrow.
　そこで本発明の目的は、広い発光角度分布を持つ光源に対して適用可能で、かつ、製作コストと波長選択に伴う光量損失が少ない導光板の技術を提供することにある。 Therefore, an object of the present invention is to provide a technology of a light guide plate that can be applied to a light source having a wide light emission angle distribution and that is low in production cost and light amount loss accompanying wavelength selection.
　上記課題を解決するために、例えば特許請求の範囲に記載の構成を採用する。本願は上記課題を解決する手段を複数含んでいるが、その一例を挙げるならば、透明基板の上面および下面に回折格子を備える導光板である。 In order to solve the above problems, for example, the configuration described in the claims is adopted. The present application includes a plurality of means for solving the above-mentioned problems. To give an example, the light guide plate includes diffraction gratings on the upper surface and the lower surface of the transparent substrate.
　また、本発明の導光板を用いた照明装置は、透明基板の上面および下面に回折格子を備える導光板と、当該導光板の所定端面に光を入射する光源と、当該光源の駆動装置とを備えたことを特徴とする。 In addition, an illumination device using the light guide plate of the present invention includes a light guide plate having diffraction gratings on the upper surface and the lower surface of a transparent substrate, a light source that makes light incident on a predetermined end surface of the light guide plate, and a drive device for the light source. It is characterized by having.
　また、本発明の装置は、透明基板の上面および下面に回折格子を備える導光板と、当該導光板の所定端面に光を入射する光源と、当該光源の駆動装置とを備えた照明装置を具備することを特徴とする。 In addition, the apparatus of the present invention includes a lighting device including a light guide plate having diffraction gratings on the upper surface and the lower surface of the transparent substrate, a light source that makes light incident on a predetermined end surface of the light guide plate, and a drive device for the light source. It is characterized by doing.
　本発明によれば、広い発光角度分布を持つ光源に対して適用可能で、かつ、製作コストと波長選択に伴う光量損失が少ない導光板を提供可能となる。 According to the present invention, it is possible to provide a light guide plate that can be applied to a light source having a wide light emission angle distribution and that has a small amount of light loss due to manufacturing cost and wavelength selection.
第１の実施例における導光板の基本構成例を示す模式図である。It is a schematic diagram which shows the basic structural example of the light-guide plate in a 1st Example. 第１及び第２の実施例の導光板に入射した入射光（波長０．４５μｍ）の光線図である。It is a light ray figure of incident light (wavelength 0.45 micrometer) which injected into the light-guide plate of the 1st and 2nd Example. 第２の実施例における導光板に入射した入射光（波長０．４５μｍ）のうち青色光に関する上面出射光の回折効率を示す図である。It is a figure which shows the diffraction efficiency of the upper surface emitted light regarding blue light among the incident light (wavelength of 0.45 micrometer) which injected into the light-guide plate in a 2nd Example. 第２の実施例における導光板に入射した入射光（波長０．４５μｍ）のうち青色光に関する上面反射光の回折効率を示す図である。It is a figure which shows the diffraction efficiency of the upper surface reflected light regarding blue light among the incident light (wavelength 0.45 micrometer) which injected into the light-guide plate in a 2nd Example. 第２の実施例における導光板に入射した入射光（波長０．４５μｍ）のうち青色光に関する、下面回折格子による１次回折光の上面回折格子による反射回折光の回折効率を示す図である。It is a figure which shows the diffraction efficiency of the reflected diffracted light by the upper surface diffraction grating of the 1st-order diffracted light by a lower surface diffraction grating regarding blue light among the incident light (wavelength 0.45 micrometer) which injected into the light-guide plate in a 2nd Example. 第２及び第３の実施例の導光板に入射した入射光（波長０．６５μｍ）の光線図である。It is a light ray figure of the incident light (wavelength 0.65 micrometer) which injected into the light-guide plate of the 2nd and 3rd Example. 第２の実施例における導光板に入射した入射光（波長０．６５μｍ）のうち赤色光に関する上面出射光の回折効率を示す図である。It is a figure which shows the diffraction efficiency of the upper surface emitted light regarding red light among the incident light (wavelength 0.65 micrometer) which injected into the light-guide plate in a 2nd Example. 第２の実施例における導光板に入射した入射光（波長０．６５μｍ）のうち赤色光に関する上面反射光の回折効率を示す図である。It is a figure which shows the diffraction efficiency of the upper surface reflected light regarding red light among the incident light (wavelength 0.65 micrometer) which injected into the light-guide plate in a 2nd Example. 第２の実施例における導光板に入射した入射光（波長０．６５μｍ）のうち赤色光に関する、下面回折格子による１次回折光の上面回折格子による反射回折光の回折効率を示す図である。It is a figure which shows the diffraction efficiency of the reflected diffracted light by the upper surface diffraction grating of the 1st-order diffracted light by a lower surface diffraction grating regarding red light among the incident light (wavelength 0.65 micrometer) which injected into the light-guide plate in a 2nd Example. 第２の実施例における導光板に関し、入射光の入射角度で平均化した上面出射効率と伝搬効率の波長特性を示す図である。It is a figure which shows the wavelength characteristic of the upper surface output efficiency and propagation efficiency which were averaged with the incident angle of incident light regarding the light-guide plate in a 2nd Example. 第２の実施例における導光板に関し、一様回折格子の場合の発光強度伝搬距離依存性を示す図である。It is a figure which shows the light emission intensity propagation distance dependence in the case of a uniform diffraction grating regarding the light-guide plate in a 2nd Example. 第２の実施例における導光板に関し、一様回折格子の場合での発光強度伝搬距離依存性を低減して発光強度分布の均一化を図る場合の、回折格子領域面積比を示す図である。It is a figure which shows the diffraction grating area | region area ratio in the case of aiming at equalization of light emission intensity distribution by reducing the light emission intensity propagation distance dependence in the case of a uniform diffraction grating regarding the light-guide plate in a 2nd Example. 第２の実施例における導光板に関し、発光強度分布の均一化を図るための伝搬損失補償後の発光強度伝搬距離依存性を示す図である。It is a figure which shows the light emission intensity propagation distance dependence after the propagation loss compensation for aiming at equalization of light emission intensity distribution regarding the light-guide plate in a 2nd Example. 第２の実施例における導光板に関し、発光スペクトルの伝搬距離依存性を示す図である。It is a figure which shows the propagation distance dependence of the light emission spectrum regarding the light-guide plate in a 2nd Example. 第３の実施例における導光板に入射した入射光（波長０．４５μｍ）のうち青色光に関する上面出射光の回折効率を示す図である。It is a figure which shows the diffraction efficiency of the upper surface emitted light regarding blue light among the incident light (wavelength 0.45 micrometer) which injected into the light-guide plate in a 3rd Example. 第３の実施例における導光板に入射した入射光（波長０．４５μｍ）のうち青色光に関する上面反射光の回折効率を示す図である。It is a figure which shows the diffraction efficiency of the upper surface reflected light regarding blue light among the incident light (wavelength 0.45 micrometer) which injected into the light-guide plate in a 3rd Example. 第３の実施例における導光板に入射した入射光（波長０．４５μｍ）のうち青色光に関する、下面回折格子による１次回折光の上面回折格子による反射回折光の回折効率を示す図である。It is a figure which shows the diffraction efficiency of the reflected diffracted light by the upper surface diffraction grating of the 1st-order diffracted light by a lower surface diffraction grating regarding blue light among the incident light (wavelength 0.45 micrometer) which injected into the light-guide plate in a 3rd Example. 第３の実施例における導光板に入射した入射光（波長０．６５μｍ）のうち赤色光に関する上面出射光の回折効率を示す図である。It is a figure which shows the diffraction efficiency of the upper surface emitted light regarding red light among the incident light (wavelength 0.65 micrometer) which injected into the light-guide plate in a 3rd Example. 第３の実施例における導光板に入射した入射光（波長０．６５μｍ）のうち赤色光に関する上面反射光の回折効率を示す図である。It is a figure which shows the diffraction efficiency of the upper surface reflected light regarding red light among the incident light (wavelength 0.65 micrometer) which injected into the light-guide plate in a 3rd Example. 第３の実施例における導光板に入射した入射光（波長０．６５μｍ）のうち赤色光に関する、下面回折格子による１次回折光の上面回折格子による反射回折光の回折効率を示す図である。It is a figure which shows the diffraction efficiency of the reflected diffracted light by the upper surface diffraction grating of the 1st-order diffracted light by a lower surface diffraction grating regarding red light among the incident light (wavelength 0.65 micrometer) which injected into the light-guide plate in a 3rd Example. 第３の実施例における導光板に関し、入射角度で平均化した上面出射効率と伝搬効率の波長特性を示す図である。It is a figure which shows the wavelength characteristic of the upper surface output efficiency and propagation efficiency which were averaged by the incident angle regarding the light-guide plate in a 3rd Example. 第３の実施例における導光板に関し、一様回折格子の場合の発光強度伝搬距離依存性を示す図である。It is a figure which shows the light emission intensity propagation distance dependence in the case of a uniform diffraction grating regarding the light-guide plate in a 3rd Example. 第３の実施例における導光板に関し、一様回折格子の場合での発光強度伝搬距離依存性を低減して発光強度分布の均一化を図る場合の、回折格子領域面積比を示す図である。It is a figure which shows the diffraction grating area | region area ratio in the case of aiming at equalization of light emission intensity distribution by reducing the light emission intensity propagation distance dependence in the case of a uniform diffraction grating regarding the light-guide plate in a 3rd Example. 第３の実施例における導光板に関し、発光強度分布の均一化を図るための伝搬損失補償後の発光強度伝搬距離依存性を示す図である。It is a figure which shows the light emission intensity propagation distance dependence after the propagation loss compensation for aiming at equalization of light emission intensity distribution regarding the light-guide plate in a 3rd Example. 第３の実施例における導光板に関し、発光スペクトルの伝搬距離依存性を示す図である。It is a figure which shows the propagation distance dependence of the emission spectrum regarding the light-guide plate in a 3rd Example. 本実施形態における導光板を用いた照明装置の構成例を示す図である。It is a figure which shows the structural example of the illuminating device using the light-guide plate in this embodiment. 本実施形態における照明装置を用いた携帯端末の構成例を示す図である。It is a figure which shows the structural example of the portable terminal using the illuminating device in this embodiment.
　以下に本発明の実施形態について図面を用いて詳細に説明する。図１は第１の実施例における導光板１００の構成例を示す図である。図１に示す導光板１００は、広い発光角度分布を持つ光源に対して適用可能で、かつ、製作コストと波長選択に伴う光量損失が少ない導光板である。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram illustrating a configuration example of a light guide plate 100 in the first embodiment. The light guide plate 100 shown in FIG. 1 is applicable to a light source having a wide light emission angle distribution, and is a light guide plate with little manufacturing cost and less light loss due to wavelength selection.
　まず第１の実施例として導光板１００の基本的な構成例について説明する。この実施例においては、図１にて示すように導光板１００が含む透明な導光板基板１０１に、白色ＬＥＤ光源１０２からの白色光１０３（入射光）が入射されている。導光板基板１０１における入射面１０１３は垂線１０１４から傾けて斜めに切り欠いてあり、入射する白色光１０３のうち最も強度が大きい光軸の光線が、導光板基板１０１内における全反射の臨界角と９０°の中間程度の所定の入射角θ０になるように設定されている。 First, a basic configuration example of the light guide plate 100 will be described as a first embodiment. In this embodiment, as shown in FIG. 1, white light 103 (incident light) from a white LED light source 102 is incident on a transparent light guide plate substrate 101 included in the light guide plate 100. The light incident surface 1013 of the light guide plate substrate 101 is obliquely cut away from the perpendicular 1014, and the light beam having the highest intensity of the incident white light 103 has a critical angle of total reflection in the light guide plate substrate 101. It is set to have a predetermined incident angle θ 0 which is about the middle of 90 °.
　導光板基板１０１は、格子深さや格子ピッチの異なる格子が形成された格子領域１０４、１０５、１０６を含んでいる。この格子領域１０４、１０５、１０６は、互いに異なる波長の光を出射させる領域であり、入射面１０１３から入射した白色光１０３は、各格子領域１０４～１０６の配置順で、領域毎の波長の光を連続的に透過させていく。 The light guide plate substrate 101 includes lattice regions 104, 105, and 106 in which lattices having different lattice depths and lattice pitches are formed. The grating regions 104, 105, and 106 are regions that emit light having different wavelengths, and the white light 103 incident from the incident surface 1013 is light having a wavelength for each region in the order in which the lattice regions 104 to 106 are arranged. Is continuously transmitted.
　また、格子領域１０４における上面１０１１のブレーズ回折格子１０７と下面１０１２のブレーズ回折格子１０８は、各格子面１０４１、１０４２の傾斜方向が互いに平行であり、格子ピッチｐと格子深さｄをそれぞれ等しくしている。同様にして格子領域１０５の上面１０１１のブレーズ回折格子１０９と下面１０１２のブレーズ回折格子１１０も、各格子面１０５１、１０５２の傾斜方向が相互に平行であり、格子ピッチｐと格子深さｄがそれぞれ等しい。格子領域１０６についても同様である。このような構成とすることにより、ブレーズ回折格子による回折角度がθ１、θ２、θ３のようになっても、上面１０１１と下面１０１２で対向するブレーズ回折格子により逆向きに回折されることにより元の入射角θ０に戻り、基本的に回折光が安定的に導光板１０の中を伝搬して行くよう図ることができる。 In the blazed diffraction grating 107 on the upper surface 1011 and the blazed diffraction grating 108 on the lower surface 1012 in the grating region 104, the inclination directions of the grating surfaces 1041 and 1042 are parallel to each other, and the grating pitch p and the grating depth d are made equal. ing. Similarly, in the blazed diffraction grating 109 on the upper surface 1011 and the blazed diffraction grating 110 on the lower surface 1012 of the grating region 105, the inclination directions of the grating surfaces 1051 and 1052 are parallel to each other, and the grating pitch p and the grating depth d are respectively set. equal. The same applies to the lattice region 106. By adopting such a configuration, even when the diffraction angles by the blazed diffraction grating become θ 1 , θ 2 , and θ 3 , they are diffracted in the opposite direction by the blazed diffraction grating facing the upper surface 1011 and the lower surface 1012. Thus, the original incident angle θ 0 is restored, and basically the diffracted light can be stably propagated through the light guide plate 10.
　なお、ブレーズ回折格子は、界面の反射率が全反射などで１００％の反射率が得られれば、ブレーズ条件を満足する入射角と波長において原理的に１００％の回折効率で回折光を得ることができる。そのような条件下では、ブレーズ格子が対向した上述のごとき導光板の中において、１００％の効率で光が伝搬できることになる。 A blazed diffraction grating can obtain diffracted light with a diffraction efficiency of 100% in principle at an incident angle and wavelength satisfying the blaze condition if the reflectance at the interface is 100% due to total reflection or the like. Can do. Under such conditions, light can propagate with 100% efficiency in the light guide plate as described above with the blazed grating facing each other.
　また、各格子領域１０４～１０６において、格子溝が連続的に配置されている単位格子領域１２０、１２２が平面領域１２１、１３を挟んで断続的に配置されている。また、単位格子領域１２０、１２２間の間隔、すなわち平面領域１２１、１２３は導光方向に向かって徐々に狭くなっている。この構成については図１では格子領域１０４についてのみ図示しているが、他の格子領域１０５、１０６でも同様である。また、格子領域１０５では、図中一番右の単位格子領域１２０１の格子数が、その前の単位格子領域１２０２、１２０３の格子数より増えている。光は基本的に導光板１００における上面１０１１の単位格子領域１２０からのみ出射されるように設計されており、局所的な出射効率が一定のため、格子が連続であれば導光距離が短いほど出射光強度が大きくなる。しかし導光板１００では導光距離によらず出射光強度が等しいことが理想であるため、このように単位格子領域を断続的にし、その間隔を変えることで平均的な出射光強度の均一化を図っている。 In each of the lattice regions 104 to 106, unit lattice regions 120 and 122 in which lattice grooves are continuously disposed are intermittently disposed with the planar regions 121 and 13 interposed therebetween. Further, the interval between the unit cell regions 120 and 122, that is, the planar regions 121 and 123 are gradually narrowed in the light guide direction. This configuration is illustrated only for the lattice region 104 in FIG. 1, but the same applies to the other lattice regions 105 and 106. In the lattice region 105, the number of lattices in the rightmost unit lattice region 1201 in the drawing is larger than the number of lattices in the previous unit lattice regions 1202 and 1203. The light is basically designed to be emitted only from the unit lattice region 120 on the upper surface 1011 of the light guide plate 100. Since the local emission efficiency is constant, the shorter the light guide distance is, the longer the lattice is. The emitted light intensity is increased. However, in the light guide plate 100, it is ideal that the output light intensity is equal regardless of the light guide distance. Thus, the unit cell region is made intermittent in this way, and the average output light intensity is made uniform by changing the interval. I am trying.
　このような出射光強度の均一化は、導光板１００の導光方向において、格子が形成されている実効面積を、入射面１０１３から離れるほど徐々に大きくして行けばよい。そこで、同じ格子本数の単位格子領域１２０、１２２の各間の間隔すなわち平面領域１２１、１２３の大きさを変える代わりに、単位格子領域１２０、１２２間の間隔は同じで、各単位格子領域１２０、１２２の格子本数を、入射面１０１３から離れるほど徐々に増やす構成としてもよい。ただし光の回折効果を得るためには、ある程度の連続する格子本数が数十本程度は必要である（なお、図１の導光板１００においては、簡略化のため格子本数は実際よりも少なく表示している）。 Such uniforming of the emitted light intensity may be achieved by gradually increasing the effective area where the grating is formed in the light guide direction of the light guide plate 100 as the distance from the incident surface 1013 increases. Therefore, instead of changing the interval between the unit lattice regions 120, 122 having the same number of lattices, that is, the size of the planar regions 121, 123, the interval between the unit lattice regions 120, 122 is the same, and each unit lattice region 120, The number of grids 122 may be gradually increased as the distance from the incident surface 1013 increases. However, in order to obtain the light diffraction effect, a certain number of continuous lattices of several tens are necessary (in the light guide plate 100 in FIG. 1, the number of lattices is smaller than the actual number for simplification. is doing).
　ＬＥＤ光源１０２から導光板１００の入射面１０１３に入射する白色入射光１０３は、λ１、λ２、λ３の３つの波長成分の光を有しており、上述の導光板１００において、格子領域１０４、１０５、１０６で格子の溝形状を変えることによって、それぞれ上面１０１１から出射する光の波長領域が異なるように設計されている。格子領域１０４ではλ１の近傍の波長帯の光が主に出射されるため、格子領域１０５に入射する光線１１３はその残りであるλ２とλ３の波長帯の光が支配的となる。また、格子領域１０５ではそのうち、λ２の光が主に出射される。同様にして格子領域１０６に入射する光線１１４ではその残りであるλ３を中心とした波長帯の光が支配的となり、格子領域１０６ではλ３の波長の光が主に出射される。 The white incident light 103 incident on the incident surface 1013 of the light guide plate 100 from the LED light source 102 has light of three wavelength components of λ1, λ2, and λ3. , 106 are designed so that the wavelength regions of the light emitted from the upper surface 1011 are different by changing the groove shape of the grating. Since light in the wavelength band near λ1 is mainly emitted in the grating region 104, the remaining light in the wavelength bands of λ2 and λ3 is dominant in the light beam 113 incident on the grating region 105. In addition, in the grating region 105, light of λ2 is mainly emitted. Similarly, in the light beam 114 incident on the grating region 106, the remaining light in the wavelength band centering on λ3 is dominant, and in the grating region 106, light having a wavelength of λ3 is mainly emitted.
　図１における導光板１００では、下面１０１２の単位格子領域１２２から上面１０１１に向かう回折光が、再び上面１０１１の対応する単位格子領域１２０に入射するように上面１０１１と下面１０１２の単位格子領域１２０、１２２の境界位置をずらしている。しかし図１中では便宜上表示していないが、下面１０１２の平坦領域１２３から上面１０１１に向かう光線が単位格子領域１２０に入り込んでしまう場合には、上面１０１１のブレーズ回折格子からの回折角がθ０に戻らなくなってしまう。しかしそれがまた安定して導光できる回折角度であれば、またその角度で導光が継続される。 In the light guide plate 100 in FIG. 1, the diffracted light traveling from the unit cell region 122 on the lower surface 1012 toward the upper surface 1011 is incident again on the corresponding unit cell region 120 on the upper surface 1011, and the unit cell regions 120 on the upper surface 1011 and the lower surface 1012. The boundary position 122 is shifted. However, although not shown in FIG. 1 for the sake of convenience, when a light beam traveling from the flat region 123 of the lower surface 1012 toward the upper surface 1011 enters the unit grating region 120, the diffraction angle from the blazed diffraction grating of the upper surface 1011 is θ 0. Will not return. However, if it is a diffraction angle at which light can be guided stably, light guide is continued at that angle.
　なお、導光板１００の上面１０１１において出射させる光は、ブレーズ回折格子の回折角の波長依存性により、特定波長で上面１０１１の透過側の回折効率が他波長より大きくなるようにさせる。この場合も、基本的に近傍波長で出射光が生じない条件であるため、出射光の出射角度は導光板基板１０１の表面すれすれの大きな出射角度となる。このため観察者が導光板表面に正対して出射光を認識できるようにするため、出射面にはエアギャップ１１８を挟んで拡散板１１５を配置している。また、この拡散板１１５を支持するため、光の出射を妨げない程度に、上面１０１１と拡散板１１５との間に支持部材１１６を配置している。また下面１０１２での透過光による光量損失を減らすために、下面１０１２には金属膜１１７をコーティングしている。 Note that the light emitted from the upper surface 1011 of the light guide plate 100 causes the diffraction efficiency on the transmission side of the upper surface 1011 to be higher than other wavelengths at a specific wavelength due to the wavelength dependence of the diffraction angle of the blazed diffraction grating. In this case as well, the condition is basically that no outgoing light is generated at a nearby wavelength, and thus the outgoing angle of the outgoing light is an outgoing angle with a large surface grazing of the light guide plate substrate 101. Therefore, in order for the observer to recognize the emitted light directly facing the surface of the light guide plate, a diffusion plate 115 is disposed on the emission surface with an air gap 118 interposed therebetween. Further, in order to support the diffusion plate 115, a support member 116 is disposed between the upper surface 1011 and the diffusion plate 115 to the extent that light emission is not hindered. In addition, the lower surface 1012 is coated with a metal film 117 in order to reduce the light amount loss due to the transmitted light on the lower surface 1012.
　続いて第２の実施例として、上述のような構造を基本的に備える導光板１００を用いて青色の波長の光を選択的に出射させる例について説明する。図２は、媒質屈折率１．５、ピッチ２．４μｍ、格子深さ０．３２μｍの対向型ブレーズ回折格子（単位格子領域に対応する）に、入射角５０°で波長０．４５μｍの青色光を入射させた場合の、回折光の光線図である。光線角度としては２次回折光から１１次回折光までが導光板１００の上面１０１１から出射できることを示しており、２次回折光以下は出射できずに全反射していることを示している。上面１０１１で反射する１次回折光のさらに－１次光回折光が元の入射光と同じ５０°の入射角で再び下面１０１２に入射している。すなわちこれが安定的な伝搬光となる。 Subsequently, as a second embodiment, an example in which light having a blue wavelength is selectively emitted using the light guide plate 100 that basically includes the above-described structure will be described. FIG. 2 shows a blue light having a wavelength of 0.45 μm at an incident angle of 50 ° on an opposed blazed diffraction grating (corresponding to a unit grating region) having a medium refractive index of 1.5, a pitch of 2.4 μm, and a grating depth of 0.32 μm. It is a light ray figure of diffracted light at the time of making enter. As for the light beam angle, it is shown that from the second-order diffracted light to the 11th-order diffracted light can be emitted from the upper surface 1011 of the light guide plate 100, and the second-order diffracted light or less cannot be emitted and is totally reflected. Further, the −1st order diffracted light of the first order diffracted light reflected by the upper surface 1011 is incident on the lower surface 1012 again at the same incident angle of 50 ° as the original incident light. That is, this becomes stable propagation light.
　図３は、上述の図２における上面１０１１から出射する各次の回折光の効率を示したものである。図３にて示すように２次回折光が約４５％の効率で上面１０１１から出射するが、他の次数は効率が小さいことがわかる。一方、図４は、上面１０１１で反射する各次の光の効率を示したものである。この図４にて示すように、１次回折光が４０％の回折効率を持って、導光板基板１０１内に反射することがわかる。 FIG. 3 shows the efficiency of each diffracted light beam emitted from the upper surface 1011 in FIG. 2 described above. As shown in FIG. 3, the second-order diffracted light is emitted from the upper surface 1011 with an efficiency of about 45%, but it can be seen that the efficiency of other orders is small. On the other hand, FIG. 4 shows the efficiency of each order of light reflected by the upper surface 1011. As can be seen from FIG. 4, the first-order diffracted light is reflected into the light guide plate substrate 101 with a diffraction efficiency of 40%.
　また、図５はもとの入射光１０３の強度を１とするときに、上面１０１で反射する１次回折光が上面１０１のブレーズ回折格子で回折される回折効率を計算したものである。安定的に伝搬できる－１次光の効率は２０％程度であることがわかる。 FIG. 5 shows a calculation result of diffraction efficiency in which the first-order diffracted light reflected from the upper surface 101 is diffracted by the blazed diffraction grating on the upper surface 101 when the intensity of the original incident light 103 is 1. It can be seen that the efficiency of −1st order light that can be stably propagated is about 20%.
　一方、図６は同じ格子に同じ入射角で波長０．６５μｍの赤色光を入射させた場合の光線図である。上面１０１１から出射できる光線は２次光から７次光であり、やはり１次回折光以下の次数は導光板基板１０１内に全反射することがわかる。また、図７は図６において上面１０１１から出射する各次の回折光の効率を示したものである。青色光同様、２次回折光が一番光量が大きいが、効率は約９％であり、青色光よりもかなり小さいことがわかる。 On the other hand, FIG. 6 is a ray diagram when red light having a wavelength of 0.65 μm is incident on the same grating at the same incident angle. It can be seen that the light rays that can be emitted from the upper surface 1011 are the second-order light to the seventh-order light, and the orders below the first-order diffracted light are also totally reflected in the light guide plate substrate 101. FIG. 7 shows the efficiency of each order of diffracted light emitted from the upper surface 1011 in FIG. Like the blue light, the second-order diffracted light has the largest amount of light, but the efficiency is about 9%, which is much smaller than the blue light.
　図８は図６において上面１０１１で反射する反射光の各次の回折効率を示したものである。１次回折光が約８０％の効率で導光板基板１０１内に反射されることがわかる。また、図９は図８において反射される１次回折光が上面１０１１の回折格子で回折されるときの回折効率を示したものである。ほぼ８０％の効率のままで、－１次光として回折され、入射光１０３と同じ入射角で伝搬光となることがわかる。 FIG. 8 shows each diffraction efficiency of the reflected light reflected from the upper surface 1011 in FIG. It can be seen that the first-order diffracted light is reflected into the light guide plate substrate 101 with an efficiency of about 80%. FIG. 9 shows the diffraction efficiency when the first-order diffracted light reflected in FIG. 8 is diffracted by the diffraction grating on the upper surface 1011. It can be seen that while the efficiency is almost 80%, it is diffracted as −1st order light and becomes propagating light at the same incident angle as the incident light 103.
　図１０は本実施例において、入射角４５°から７５°までの角度範囲で平均化した、上面出射効率と伝搬効率である。図１０のグラフ横軸において波長の短い領域に対応する青色光の伝搬効率が低く、出射効率は大きいことがわかる。 FIG. 10 shows the top surface emission efficiency and propagation efficiency averaged over an angle range from 45 ° to 75 ° in the present embodiment. It can be seen from the horizontal axis of the graph of FIG. 10 that the blue light propagation efficiency corresponding to the short wavelength region is low and the emission efficiency is large.
　図１１は、導光板基板１０１の厚さ３ｍｍ、回折領域が連続的に形成された構造（離散的でなく、平面領域１２１らが存在しない構造）において、伝搬長さあたりの出射光量から均一に光が出射されると仮定した場合の、伝搬距離に対する単位長さあたりの発光強度を対数で示したものである。このグラフに示すとおり、青色光が伝搬距離０では発光強度が大きいものの、伝搬距離がのびるに従って急激に強度低下することがわかる。 FIG. 11 shows the light guide plate substrate 101 with a thickness of 3 mm and a structure in which diffraction regions are continuously formed (a structure that is not discrete and does not include the planar region 121) and is uniform from the amount of light emitted per propagation length. This is a logarithm of the light emission intensity per unit length with respect to the propagation distance when it is assumed that light is emitted. As shown in this graph, although the emission intensity of blue light is large at a propagation distance of 0, it can be seen that the intensity rapidly decreases as the propagation distance increases.
　一方、図１２は、図１１の状況を改善して発光強度の均一化を図るべく、導光板１００の導光方向の伝搬距離のうち回折格子領域を設ける比率を示したものである。ここでは、伝搬距離１００ｍｍを想定し、光線入射位置では格子領域の比率は約１０％、そこから伝搬距離がのびるに従って徐々に比率を高くするように設定している。こうした措置を施した導光板における発光強度分布は図１３に示すとおりとなる。図１３は図１２の特性に基づいて補償された導光板における発光強度分布を波長ごとに示したものである。図１１のグラフと異なり、縦軸は対数ではなく線形座標である。この図１２のグラフにおいて、伝搬距離５０ｍｍ程度までは波長０．４５μｍの青色光の強度が大きくなっていることがわかる。 On the other hand, FIG. 12 shows the ratio of providing the diffraction grating region in the propagation distance in the light guide direction of the light guide plate 100 in order to improve the situation of FIG. 11 and make the light emission intensity uniform. Here, assuming a propagation distance of 100 mm, the ratio of the grating region is set to about 10% at the light incident position, and the ratio is set to gradually increase as the propagation distance increases from there. The light emission intensity distribution in the light guide plate subjected to such measures is as shown in FIG. FIG. 13 shows the emission intensity distribution in the light guide plate compensated based on the characteristics of FIG. 12 for each wavelength. Unlike the graph of FIG. 11, the vertical axis is not logarithmic but linear coordinates. In the graph of FIG. 12, it can be seen that the intensity of blue light having a wavelength of 0.45 μm increases up to a propagation distance of about 50 mm.
　また、図１４は、上述の補償された導光板における伝搬距離ごとの発光スペクトルを示した図である。このグラフにおいて、伝搬距離が短い間は青色光が支配的であるが、伝搬距離が長くなってくると赤色の光が支配的になってくることがわかる。 FIG. 14 is a diagram showing an emission spectrum for each propagation distance in the compensated light guide plate. In this graph, it can be seen that blue light is dominant when the propagation distance is short, but red light becomes dominant as the propagation distance becomes longer.
　次に、第３の実施例として、導光板１００において赤色の波長の光を選択的に出射させる構成例について説明する。なお、光線図はピッチと波長が等しい図３と同一である。図１５は、媒質屈折率１．５、ピッチ２．４μｍ、格子深さ０．２１μｍの対向型ブレーズ回折格子に、入射角５０°で波長０．４５μｍの青色光を入射させた場合の、上面１０１１から出射する各次の回折光の効率を示したものである。２次回折光以上の回折光が出射するが、その効率は３％以下と小さいことがわかる。 Next, as a third embodiment, a configuration example in which light having a red wavelength is selectively emitted from the light guide plate 100 will be described. Note that the ray diagram is the same as FIG. 3 with the same pitch and wavelength. FIG. 15 shows the top surface when blue light having a wavelength of 0.45 μm is incident on an opposing blazed diffraction grating having a medium refractive index of 1.5, a pitch of 2.4 μm, and a grating depth of 0.21 μm. The efficiency of each diffracted light emitted from 1011 is shown. Although the diffracted light of the second order or higher is emitted, it can be seen that the efficiency is as small as 3% or less.
　また図１６は、上面１０１１で反射する各次の光の効率を示したものである。このグラフにおいて、１次回折光が８０％以上の回折効率を持って、導光板基板１０１内に反射することがわかる。 FIG. 16 shows the efficiency of each subsequent light reflected from the upper surface 1011. In this graph, it can be seen that the first-order diffracted light is reflected into the light guide plate substrate 101 with a diffraction efficiency of 80% or more.
　また図１７は、もとの入射光１０３の強度を１とするときに、上面１０１１で反射する１次回折光が上面１０１１のブレーズ回折格子で回折される回折効率を計算したものである。このグラフにおいて、安定的に伝搬できる－１次光の効率は８０％以上であることがわかる。 FIG. 17 shows a calculation result of diffraction efficiency in which the first-order diffracted light reflected from the upper surface 1011 is diffracted by the blazed diffraction grating on the upper surface 1011 when the intensity of the original incident light 103 is 1. In this graph, it can be seen that the efficiency of −1st order light that can be stably propagated is 80% or more.
　一方、図１８は同じ格子に同じ入射角で波長０．６５μｍの赤色光を入射させた場合の上面１０１１から出射する回折光の各次の効率を示したものである。このグラフにおいては、青色光と異なり、１次回折光が４０％以上の効率で出射することがわかる。 On the other hand, FIG. 18 shows the efficiency of each order of diffracted light emitted from the upper surface 1011 when red light having a wavelength of 0.65 μm is incident on the same grating at the same incident angle. In this graph, it can be seen that, unlike blue light, first-order diffracted light is emitted with an efficiency of 40% or more.
　また図１９は、上述の図１８のグラフで示した上面１０１１で反射する反射光の回折効率を示したものである。このグラフにおいて、０次光と１次回折光が約２０％の効率で導光板基板１０１内に反射されることがわかる。 FIG. 19 shows the diffraction efficiency of the reflected light reflected from the upper surface 1011 shown in the graph of FIG. In this graph, it can be seen that the 0th order light and the 1st order diffracted light are reflected into the light guide plate substrate 101 with an efficiency of about 20%.
　また図２０は、図１９のグラフで示した、反射される１次回折光が上面１０１１の回折格子で回折されるときの回折効率を示したものである。このグラフにおいて、ほぼ２０％の効率のままで、－１次光として回折され、入射光１０３と同じ入射角で伝搬光となることがわかる。図１９のグラフにおいて、０次光も同等程度の光量であったため、元の入射角で伝搬する光はこれも合わせて約４０％と推定される。 FIG. 20 shows the diffraction efficiency when the reflected first-order diffracted light shown in the graph of FIG. 19 is diffracted by the diffraction grating on the upper surface 1011. In this graph, it can be seen that the light is diffracted as −1st order light with an efficiency of almost 20%, and becomes propagating light at the same incident angle as the incident light 103. In the graph of FIG. 19, since the 0th-order light has the same amount of light, the light propagating at the original incident angle is estimated to be about 40%.
　図２１は、本実施例において、入射角４５°から７５°までの角度範囲で平均化した、上面出射効率と伝搬効率を示す図である。図１０のグラフと異なり、赤色光の伝搬効率が低く、出射光量が大きいことがわかる。 FIG. 21 is a diagram showing the upper surface emission efficiency and propagation efficiency averaged over an angle range from an incident angle of 45 ° to 75 ° in the present example. Unlike the graph of FIG. 10, it can be seen that the propagation efficiency of red light is low and the amount of emitted light is large.
　また図２２は、導光板基板１０１の厚さ３ｍｍ、回折格子領域が連続的に形成された構造（離散的でなく平面領域１２１らが存在しない構造）であり、伝搬長さあたりの出射光量から均一に光が出射されると仮定した場合の、伝搬距離に対する単位長さあたりの発光強度を対数で示したグラフである。このグラフにおいて、赤色光が伝搬距離０では発光強度が大きいものの、伝搬距離によって急激に強度が低下することがわかる。 FIG. 22 shows a structure in which the light guide plate substrate 101 has a thickness of 3 mm and diffraction grating regions are continuously formed (a structure that is not discrete and does not include the planar region 121). It is the graph which showed the emitted light intensity per unit length with respect to propagation distance by the logarithm on the assumption that light is radiate | emitted uniformly. In this graph, it can be seen that although red light has a large emission intensity at a propagation distance of 0, the intensity rapidly decreases with the propagation distance.
　また図２３は、図２２の状況を改善して発光強度の均一化を図るべく、導光板１００の導光方向の伝搬距離のうち回折格子領域を設ける比率を示したものである。ここでは、伝搬距離１００ｍｍを想定し、光線入射位置では格子領域の比率は約１０％、そこから伝搬距離がのびるに従って徐々に比率を高くするように設定している。こうした措置を施した導光板における発光強度分布は図２４に示すとおりとなる。図２４は図２３の特性に基づいて補償された導光板における発光強度分布を波長ごとに示したものである。図２２グラフと異なり、縦軸は対数ではなく線形座標である。この図２４のグラフにおいて、伝搬距離８０ｍｍ程度までは波長０．６～０．６５μｍの赤色光の強度が大きくなっていることがわかる。 FIG. 23 shows the ratio of providing the diffraction grating region in the propagation distance in the light guide direction of the light guide plate 100 in order to improve the situation of FIG. 22 and make the light emission intensity uniform. Here, assuming a propagation distance of 100 mm, the ratio of the grating region is set to about 10% at the light incident position, and the ratio is set to gradually increase as the propagation distance increases from there. The light emission intensity distribution in the light guide plate subjected to such measures is as shown in FIG. FIG. 24 shows the emission intensity distribution in the light guide plate compensated based on the characteristics of FIG. 23 for each wavelength. Unlike the graph of FIG. 22, the vertical axis is not a logarithm but a linear coordinate. In the graph of FIG. 24, it can be seen that the intensity of red light having a wavelength of 0.6 to 0.65 μm is increased up to a propagation distance of about 80 mm.
　また図２５は、伝搬距離ごとの発光スペクトルを示した図である。このグラフにおいて、伝搬距離が短い間は赤色光が支配的であるが、伝搬距離が長くなってくると青色の光が支配的になってくることがわかる。 FIG. 25 is a diagram showing an emission spectrum for each propagation distance. In this graph, it can be seen that red light is dominant when the propagation distance is short, but blue light becomes dominant as the propagation distance becomes longer.
　続いて、上述してきた導光板１００を実装した構成の具体例について説明する。図２６は本実施形態における導光板１００を用いた照明装置２００の構成例を示す図である。従来型の導光板１００は、液晶パネルのバックライトなど単色光の光源として用いられることが多かった。一方、図２６においては、複数の色の光を発光する照明装置２００として導光板１００を実装した例を示している。 Subsequently, a specific example of a configuration in which the light guide plate 100 described above is mounted will be described. FIG. 26 is a diagram illustrating a configuration example of an illumination device 200 using the light guide plate 100 in the present embodiment. The conventional light guide plate 100 is often used as a monochromatic light source such as a backlight of a liquid crystal panel. On the other hand, FIG. 26 shows an example in which the light guide plate 100 is mounted as the illumination device 200 that emits light of a plurality of colors.
　この照明装置２００は、樹脂や金属で構成された適宜な強度および放熱効率を備えた筐体２１０と、この筐体２１０のうち一つの面に填め込み設置されたガラスパネル２０１と、このガラスパネル２０１の下方にあって、拡散板１１５を介して光を出射させる導光板１００と、この導光板１００の端面に入射光を照射する白色ＬＥＤ光源１０２と、当該白色ＬＥＤ光源１０２を駆動、制御するドライバＩＣなどＬＥＤ駆動回路２０２（駆動装置）と、このＬＥＤ駆動回路２０２に電気を供給する電源２０５とから構成される。 The lighting device 200 includes a casing 210 made of resin or metal and having appropriate strength and heat dissipation efficiency, a glass panel 201 fitted in one surface of the casing 210, and the glass panel. A light guide plate 100 that emits light via a diffuser plate 115, a white LED light source 102 that irradiates incident light on the end surface of the light guide plate 100, and the white LED light source 102 is driven and controlled. An LED driving circuit 202 (driving device) such as a driver IC and a power source 205 that supplies electricity to the LED driving circuit 202 are configured.
　また図２７は本実施形態における照明装置２００を用いた携帯端末３００の構成例を示す図である。上述した照明装置２００を組み込んで、ユーザに対する注意喚起や各種の情報伝達用に発光を利用する携帯端末３００の例を示す。この携帯端末３００では、液晶画面３０１の一部に組み込んだ照明装置２００が、導光方向の距離によらず均一な光を波長選択的に出射する。図２７の例では、照明装置２００における導光板１００が赤、緑、青の計３色を出射させている。 FIG. 27 is a diagram illustrating a configuration example of the mobile terminal 300 using the lighting device 200 according to the present embodiment. The example of the portable terminal 300 which incorporates the illuminating device 200 mentioned above and utilizes light emission for alerting a user or transmitting various information is shown. In this portable terminal 300, the illumination device 200 incorporated in a part of the liquid crystal screen 301 emits uniform light in a wavelength selective manner regardless of the distance in the light guide direction. In the example of FIG. 27, the light guide plate 100 in the illumination device 200 emits a total of three colors of red, green, and blue.
　こうした導光板１００の実装例としては、上述の例のみに限定されない。例えば、導光板１００を自動車など各種輸送機械の表示用ランプ（車体外装のヘッドランプやテールランプ、方向指示器、或いは車体内装の室内灯、表示計器用ランプ）に適用出来る。 The mounting example of such a light guide plate 100 is not limited to the above example. For example, the light guide plate 100 can be applied to display lamps (head lamps and tail lamps on the exterior of the vehicle body, turn indicators, interior lamps on the vehicle interior, and display instrument lamps) for various transport machines such as automobiles.
　以上、本発明を実施するための最良の形態などについて具体的に説明したが、本発明はこれに限定されるものではなく、その要旨を逸脱しない範囲で種々変更可能である。 The best mode for carrying out the present invention has been specifically described above. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention.
　こうした本実施形態によれば、広い発光角度分布を持つ光源に対して適用可能で、かつ、製作コストと波長選択に伴う光量損失が少ない導光板を提供可能となる。 According to the present embodiment, it is possible to provide a light guide plate that can be applied to a light source having a wide light emission angle distribution and that has a small amount of light loss due to manufacturing cost and wavelength selection.
　本明細書の記載により、少なくとも次のことが明らかにされる。すなわち、本実施形態の導光板において、前記回折格子は透明基板の凹凸によって形成されたものであるとすれば好適である。 記載 At least the following will be made clear by the description in this specification. That is, in the light guide plate of the present embodiment, it is preferable that the diffraction grating is formed by unevenness of the transparent substrate.
　これによれば、導光板形成に際し、基板材料と異なる材料や複雑なプロセスは不要となり、導光板生成に必要な機器や工程時間等のコストを低廉なものとできる。
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　また、本実施形態の導光板において、前記回折格子は、連続する溝状の格子によって形成される格子領域が、導光方向にそって離散的に複数形成されたものであるとしてもよい。 According to this, when forming the light guide plate, a material different from the substrate material and a complicated process are not necessary, and the costs such as equipment and process time required for generating the light guide plate can be reduced.
In the light guide plate of the present embodiment, the diffraction grating may be formed by discretely forming a plurality of grating regions formed by continuous groove-shaped gratings along the light guide direction.
　これによれば、溝状の格子領域での光の出射および反射と、格子領域間の平坦面での光の全反射とを適宜に組み合わせることで、光量損失を抑制しつつ、導光方向に沿って（出射光の）発光強度を均一化出来る。 According to this, by appropriately combining the emission and reflection of light in the groove-like lattice region and the total reflection of light on the flat surface between the lattice regions, the light amount loss is suppressed and the light guide direction is reduced. The light emission intensity (outgoing light) can be made uniform along.
　また、本実施形態の導光板において、前記離散的に複数形成された格子領域間の間隔が、導光方向に沿って漸次狭くなっているとしてもよい。 Further, in the light guide plate of the present embodiment, the interval between the plurality of discretely formed lattice regions may be gradually narrowed along the light guide direction.
　これによれば、単位導光距離あたりの格子領域の存在密度を低くすることにより、導光板への入射位置近辺での出射光強度を適宜に抑える一方、単位導光距離あたりの格子領域の存在密度を高くすることにより、入射位置から離れた位置でも適宜な出射光強度を得られることになる。 According to this, by reducing the density of the lattice area per unit light guide distance, the intensity of emitted light near the incident position on the light guide plate is appropriately suppressed, while the presence of the lattice area per unit light guide distance is suppressed. By increasing the density, an appropriate emitted light intensity can be obtained even at a position away from the incident position.
　また、本実施形態の導光板において、前記離散的に複数形成された各格子領域における格子数が、導光方向に沿って漸次多くなっているとしてもよい。 Further, in the light guide plate of the present embodiment, the number of lattices in each of the plurality of discretely formed lattice regions may be gradually increased along the light guide direction.
　これによれば、格子領域における格子数を少なくすることにより、導光板への入射位置近辺での出射光強度を適宜に抑える一方、格子領域における格子数を多くすることにより、入射位置から離れた位置でも適宜な出射光強度を得られることになる。 According to this, by reducing the number of gratings in the grating region, the intensity of the emitted light near the incident position on the light guide plate is appropriately suppressed, while by increasing the number of gratings in the grating region, the distance from the incident position is increased. An appropriate outgoing light intensity can be obtained even at the position.
　また、本実施形態の導光板において、前記回折格子はブレーズ回折格子であって、前記上面の回折格子と前記下面の回折格子との間で各格子面の傾斜方向が同じであるとすれば好適である。 In the light guide plate of the present embodiment, it is preferable that the diffraction grating is a blazed diffraction grating, and the inclination directions of the grating surfaces are the same between the diffraction grating on the upper surface and the diffraction grating on the lower surface. It is.
　これによれば、導光板の端面から入射した入射光が、上面と下面の各回折格子の格子面間で反射角度を乱すことなく伝搬を続けることが可能となり、光量損失を効果的に低減出来る。 According to this, it becomes possible for the incident light incident from the end face of the light guide plate to continue to propagate without disturbing the reflection angle between the grating surfaces of the diffraction gratings on the upper surface and the lower surface, thereby effectively reducing the light amount loss. .
　また、本実施形態の導光板において、前記回折格子はブレーズ回折格子であって、前記上面および前記下面の各回折格子のうちいずれか一方の格子面は、導光する光の入射角が大きくなる方向に傾斜し、他方の格子面は、導光する光の入射角が小さくなる方向に傾斜しているものであるとすれば好適である。 In the light guide plate of the present embodiment, the diffraction grating is a blazed diffraction grating, and one of the diffraction gratings on the upper surface and the lower surface has a large incident angle of light to be guided. It is preferable that the other lattice plane is inclined in the direction in which the incident angle of light to be guided is reduced.
　これによれば、導光板の端面から入射した入射光が、上面と下面の各回折格子の格子面間で反射角度を乱すことなく伝搬を続けることが可能であり、更に、上面または下面の一方に出射光を透過させ、光量損失を更に効果的に低減出来る。 According to this, the incident light incident from the end face of the light guide plate can continue to propagate between the grating surfaces of the diffraction gratings on the upper surface and the lower surface without disturbing the reflection angle. The transmitted light can be transmitted to the light source, and the light amount loss can be further effectively reduced.
　また、本実施形態の導光板において、前記各回折格子の格子面のうち、導光する光の入射角が小さくなる方向に傾斜した格子面は、金属膜が蒸着されているものであるとすれば好適である。 Further, in the light guide plate of the present embodiment, among the grating surfaces of the diffraction gratings, the grating surface inclined in the direction in which the incident angle of the light to be guided is reduced is assumed to be a metal film deposited. Is preferable.
　これによれば、導光板の端面から入射した入射光が、上面と下面の各回折格子の格子面間で反射角度を乱すことなく伝搬を続けることが可能であり、更に、上面または下面の一方に出射光を透過させると共に、他方の面からの出射を抑止して、光量損失を更に効果的に低減出来る。 According to this, the incident light incident from the end face of the light guide plate can continue to propagate between the grating surfaces of the diffraction gratings on the upper surface and the lower surface without disturbing the reflection angle. Thus, it is possible to more effectively reduce the light loss by transmitting the outgoing light to the light source and suppressing the outgoing light from the other surface.
　また、本実施形態の導光板において、当該導光板の外面のうち、前記導光する光の入射角が大きくなる方向に傾斜した格子面と近接した面側に、拡散面を有する部材が配置されているとすれば好適である。 In the light guide plate of the present embodiment, a member having a diffusion surface is disposed on the outer surface of the light guide plate on the surface side close to the lattice surface inclined in the direction in which the incident angle of the light to be guided increases. If so, it is preferable.
　これによれば、前記近接した面からの出射光の出射角によらず、導光板外に向けて均一に拡散された光を放射することが可能となる。 According to this, it becomes possible to radiate light uniformly diffused out of the light guide plate regardless of the emission angle of the emitted light from the adjacent surfaces.
　また、本実施形態の導光板において、前記回折格子の格子深さまたは格子ピッチが異なる複数の格子領域が、導光方向に沿って配置されているとしてもよい。 Further, in the light guide plate of this embodiment, a plurality of grating regions having different grating depths or grating pitches of the diffraction grating may be arranged along the light guide direction.
　これによれば、光源から導光板に入射した光を、導光方向の所定位置で所望波長毎に透過させることが可能となる。 According to this, it becomes possible to transmit the light incident on the light guide plate from the light source for each desired wavelength at a predetermined position in the light guide direction.
　また、本実施形態の導光板において、導光させる光を入射する端面が透明基板面に対する角度は、当該導光板内において導光する光の伝搬効率が所定以上となる範囲の角度であって、垂直でないとすれば好適である。 Further, in the light guide plate of the present embodiment, the angle of the end surface on which the light to be guided is incident with respect to the transparent substrate surface is an angle in a range where the propagation efficiency of the light guided in the light guide plate is equal to or greater than a predetermined value. If it is not vertical, it is preferable.
　これによれば、導光板の端面から入射した入射光が、上面と下面の各回折格子の格子面間で反射角度を乱すことなく効率よく伝搬を続けることが可能となり、光量損失を効果的に低減出来る。 According to this, it becomes possible for incident light incident from the end face of the light guide plate to continue to propagate efficiently without disturbing the reflection angle between the grating surfaces of the upper and lower diffraction gratings, effectively reducing the amount of light loss. It can be reduced.
１００　導光板
１０１　導光板基板
１０１１　基板上面
１０１２　基板下面
１０１３　入射面
１０２　白色ＬＥＤ光源
１０３　入射白色光線（入射光）
１０４　第１の波長の出射領域
１０４１、１０４２　格子面
１０５　第２の波長の出射領域
１０５１、１０５２　格子面
１０６　第３の波長の出射領域
１０６１、１０６２　格子面
１０７　第１の波長の出射領域の上面ブレーズ回折格子
１０８　第１の波長の出射領域の下面ブレーズ回折格子
１０９　第２の波長の出射領域の上面ブレーズ回折格子
１１０　第２の波長の出射領域の下面ブレーズ回折格子
１１１　第３の波長の出射領域の上面ブレーズ回折格子
１１２　第３の波長の出射領域の下面ブレーズ回折格子
１１３　第２の波長の出射領域の入射光線
１１４　第３の波長の出射領域の入射光線
１１５　拡散板
１１６　拡散板支持部材
１１７　金属反射膜
１２０　単位格子領域
２００　照明装置
２０１　ガラスパネル
２０２　ＬＥＤ駆動回路（駆動装置）
２０５　電源
２１０　筐体
３００　携帯端末
３０１　液晶画面 100 light guide plate 101 light guide plate substrate 1011 substrate upper surface 1012 substrate lower surface 1013 incident surface 102 white LED light source 103 incident white light (incident light)
104 Emission areas 1041 and 1042 of the first wavelength Lattice surface 105 Emission areas 1051 and 1052 of the second wavelength Lattice surface 106 Emission areas 1061 and 1062 of the third wavelength Lattice surface 107 Upper surface blaze of the emission area of the first wavelength Diffraction grating 108 Bottom blazed diffraction grating 109 in first wavelength emission region Top blazed diffraction grating 110 in second wavelength emission region Bottom blazed diffraction grating 111 in second wavelength emission region 111 Upper surface blazed diffraction grating 112 Lower surface blazed diffraction grating 113 in the third wavelength exit region 113 Incident beam 114 in the second wavelength exit region 115 Incident beam 115 in the third wavelength exit region Diffusion plate 116 Diffusion plate support member 117 Metal reflection Film 120 Unit lattice area 200 Illumination device 201 Glass panel 202 LED drive circuit (drive device)
205 Power supply 210 Case 300 Mobile terminal 301 Liquid crystal screen

Claims (13)

  1. 　透明基板の上面および下面に回折格子を備える導光板。 A light guide plate with diffraction gratings on the upper and lower surfaces of a transparent substrate.
  2. 　前記回折格子は透明基板の凹凸によって形成されたものであることを特徴とする請求項１に記載の導光板。 The light guide plate according to claim 1, wherein the diffraction grating is formed by unevenness of a transparent substrate.
  3. 　前記回折格子は、連続する溝状の格子によって形成される格子領域が、導光方向にそって離散的に複数形成されたものであることを特徴とする請求項１に記載の導光板。 2. The light guide plate according to claim 1, wherein the diffraction grating is formed by discretely forming a plurality of lattice regions formed by continuous groove-shaped gratings along a light guide direction.
  4. 　前記離散的に複数形成された格子領域間の間隔が、導光方向に沿って漸次狭くなっていることを特徴とする請求項３に記載の導光板。 The light guide plate according to claim 3, wherein an interval between the plurality of discretely formed lattice regions is gradually narrowed along a light guide direction.
  5. 　前記離散的に複数形成された各格子領域における格子数が、導光方向に沿って漸次多くなっていることを特徴とする請求項３に記載の導光板。 4. The light guide plate according to claim 3, wherein the number of lattices in each of the plurality of discretely formed lattice regions is gradually increased along the light guide direction.
  6. 　前記回折格子はブレーズ回折格子であって、前記上面の回折格子と前記下面の回折格子との間で各格子面の傾斜方向が同じであることを特徴とする請求項１に記載の導光板。 2. The light guide plate according to claim 1, wherein the diffraction grating is a blazed diffraction grating, and an inclination direction of each grating surface is the same between the diffraction grating on the upper surface and the diffraction grating on the lower surface.
  7. 　前記回折格子はブレーズ回折格子であって、前記上面および前記下面の各回折格子のうちいずれか一方の格子面は、導光する光の入射角が大きくなる方向に傾斜し、他方の格子面は、導光する光の入射角が小さくなる方向に傾斜しているものであることを特徴とする請求項１に記載の導光板。 The diffraction grating is a blazed diffraction grating, and one of the upper and lower diffraction gratings is inclined in a direction in which an incident angle of light to be guided is increased, and the other grating surface is The light guide plate according to claim 1, wherein the light guide plate is inclined in a direction in which an incident angle of light to be guided decreases.
  8. 　前記各回折格子の格子面のうち、導光する光の入射角が小さくなる方向に傾斜した格子面は、金属膜が蒸着されているものであることを特徴とする請求項７に記載の導光板。 8. The guide according to claim 7, wherein among the grating surfaces of the diffraction gratings, a grating surface inclined in a direction in which an incident angle of light to be guided is reduced is a metal film deposited thereon. Light board.
  9. 　当該導光板の外面のうち、前記導光する光の入射角が大きくなる方向に傾斜した格子面と近接した面側に、拡散面を有する部材が配置されていることを特徴とする請求項７に記載の導光板。 8. A member having a diffusing surface is disposed on the outer surface of the light guide plate on a surface side close to a lattice surface inclined in a direction in which an incident angle of the light to be guided increases. The light guide plate described in 1.
  10. 　前記回折格子の格子深さまたは格子ピッチが異なる複数の格子領域が、導光方向に沿って配置されていることを特徴とする請求項１に記載の導光板。 The light guide plate according to claim 1, wherein a plurality of grating regions having different grating depths or grating pitches of the diffraction grating are arranged along a light guide direction.
  11. 　導光させる光を入射する端面が透明基板面に対する角度は、当該導光板内において導光する光の伝搬効率が所定以上となる範囲の角度であって、垂直でないことを特徴とする請求項１の導光板。 The angle between the end face on which the light to be guided is incident on the transparent substrate surface is an angle in a range where the propagation efficiency of the light guided in the light guide plate is not less than a predetermined value, and is not vertical. Light guide plate.
  12. 　透明基板の上面および下面に回折格子を備える導光板と、当該導光板の所定端面に光を入射する光源と、当該光源の駆動装置とを備えたことを特徴とする照明装置。 An illumination device comprising: a light guide plate having diffraction gratings on an upper surface and a lower surface of a transparent substrate; a light source that makes light incident on a predetermined end surface of the light guide plate; and a drive device for the light source.
  13. 　透明基板の上面および下面に回折格子を備える導光板と、当該導光板の所定端面に光を入射する光源と、当該光源の駆動装置とを備えた照明装置を具備することを特徴とする装置。 An apparatus comprising: a light guide plate having diffraction gratings on an upper surface and a lower surface of a transparent substrate; a light source that impinges light on a predetermined end surface of the light guide plate; and a driving device for the light source.
PCT/JP2014/059823 2014-04-03 2014-04-03 Light guide plate, and device using light guide plate WO2015151255A1 (en)

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US11143810B2 (en) * 2017-04-04 2021-10-12 Leia Inc. Unilateral backlight, multiview display, and method employing slanted diffraction gratings
JP2022530185A (en) * 2019-04-03 2022-06-28 カール ツァイス イエナ ゲゼルシャフト ミット ベシュレンクテル ハフツング A device that generates light distribution using an optical waveguide
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US11812738B2 (en) 2010-03-08 2023-11-14 Monsanto Technology Llc Polynucleotide molecules for gene regulation in plants
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