WO2013046276A1 - Illumination device and liquid-crystal display device using this - Google Patents

Illumination device and liquid-crystal display device using this Download PDF

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Publication number
WO2013046276A1
WO2013046276A1 PCT/JP2011/005524 JP2011005524W WO2013046276A1 WO 2013046276 A1 WO2013046276 A1 WO 2013046276A1 JP 2011005524 W JP2011005524 W JP 2011005524W WO 2013046276 A1 WO2013046276 A1 WO 2013046276A1
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WO
WIPO (PCT)
Prior art keywords
light
guide plate
light guide
led
inclined surface
Prior art date
Application number
PCT/JP2011/005524
Other languages
French (fr)
Japanese (ja)
Inventor
誠治 村田
真弓 長▲吉▼
大内　敏
将史 山本
Original Assignee
日立コンシューマエレクトロニクス株式会社
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Application filed by 日立コンシューマエレクトロニクス株式会社 filed Critical 日立コンシューマエレクトロニクス株式会社
Priority to PCT/JP2011/005524 priority Critical patent/WO2013046276A1/en
Publication of WO2013046276A1 publication Critical patent/WO2013046276A1/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
    • G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
    • G02B6/0015—Means for improving the coupling-in of light from the light source into the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/0018—Redirecting means on the surface of the light guide
    • 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
    • G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
    • G02B6/0015—Means for improving the coupling-in of light from the light source into the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/002—Means for improving the coupling-in of light from the light source into the light guide provided on the surface of the light guide or in the bulk of it by shaping at least a portion of the light guide, e.g. with collimating, focussing or diverging surfaces
    • G02B6/0021—Means for improving the coupling-in of light from the light source into the light guide provided on the surface of the light guide or in the bulk of it by shaping at least a portion of the light guide, e.g. with collimating, focussing or diverging surfaces for housing at least a part of the light source, e.g. by forming holes or recesses
    • 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
    • G02B6/0075—Arrangements of multiple light guides
    • G02B6/0078—Side-by-side arrangements, e.g. for large area displays

Definitions

  • the present invention relates to an illumination device and a liquid crystal display device using the same as a backlight.
  • Edge light type is a flat light guide made of transparent resin for point light such as LEDs. Since it is the structure which irradiates a liquid crystal panel by making it planar light with an optical plate, it is advantageous to thickness reduction (reduction of a depth dimension) of a video display apparatus.
  • Patent Document 1 As a conventional technology of a backlight device using such a light guide plate, for example, the one described in Patent Document 1 is known.
  • Patent Document 1 a plurality of concave portions having a horizontal direction as a longitudinal direction are provided on the bottom surface of the light guide plate in the vertical direction, a plurality of side emission LEDs are stored in the respective concave portions, and light from the LEDs is reflected inside the light guide plate. It discloses that the light is emitted to the liquid crystal panel side.
  • JP 2006-236701 A Japanese Patent Laid-Open No. 2005-117023 Japanese Laid-Open Patent Publication No. 2003-242817
  • a side emission type (side view type) LED is used as the LED.
  • a direction directly above the LED that is, a direction orthogonal to the optical axis direction of the side view type LED.
  • There is light traveling toward the liquid crystal panel. For example, the light transmitted through the LED package, the light reflected from the inner wall surface of the recess, or the reflection sheet disposed on the back side of the light guide plate.
  • Bright lines are generated and are visually recognized as uneven brightness.
  • the above-mentioned patent document does not consider this point.
  • the present invention has been made in view of the above-described problems of the prior art, and provides a technique capable of reducing luminance unevenness and obtaining a uniform luminance distribution while improving light utilization efficiency. .
  • the present invention is characterized by the structure described in the claims.
  • the present invention relates to a plurality of light sources, a light guide plate for emitting light from the light sources as planar light, and a light distribution adjusting sheet disposed on the light emission side of the light guide plate.
  • the optical axis of the light source is substantially parallel to the light emitting surface of the light guide plate or the back surface thereof, and a recess for storing the light source is provided on the back side of the light guide plate,
  • An inclined surface is provided at a position corresponding to the concave portion or the light source on the light emitting surface of the light guide plate, and the inclined surface is formed so as to go from the back surface of the light guide plate to the light emitting surface according to the optical axis direction of the LED.
  • the angle of the inclined surface is inclined more than a critical angle of the light guide plate with respect to air when the direction perpendicular to the light emitting surface of the light guide plate is used as a reference.
  • the present invention can provide an illumination device that is advantageous for thinning the device, has high luminance and high luminance uniformity, and is suitable for applying area dimming, and a liquid crystal display device using the same.
  • the liquid crystal display device includes a plurality of LEDs (Light Emitting Diode) 1 serving as light sources and the liquid crystal panel 5 side by converting the light from the LEDs 1 into planar light.
  • LEDs Light Emitting Diode
  • a light guide plate 2 having a flat plate shape for emitting light, a plurality of LEDs 1, a light source substrate 3 on which electronic components (not shown) such as drivers for supplying current to the LEDs 1 are mounted, and light of the light guide plate 2
  • a light distribution adjusting sheet 4 provided at a predetermined distance from the emission surface (surface facing the liquid crystal panel 5), and a liquid crystal panel 5 irradiated with light transmitted through the light distribution adjusting sheet 4;
  • a reflection sheet 7 provided on the back side of the light guide plate 2 and a chassis 9.
  • the LED 1, the light guide plate 2, the light source substrate 3, the light distribution adjustment sheet 4, and the reflection sheet 7 constitute an illumination device of the liquid crystal display device according to the present embodiment, that is, a backlight device.
  • the lighting device may further include a chassis 9.
  • the light guide plate 2 is composed of a plurality of light guide plate blocks 2a, 2b and 2c, and each of the light guide plate blocks 2a, 2b and 2c has a plurality of (four in this embodiment) LEDs. Is provided. Further, as shown in FIG. 2, the LED 1 is housed on the back surface (surface opposite to the light emission surface and facing the surface of the light source substrate 3) of each light guide plate block 2a, 2b, 2c. A recess 6 is provided. The recess 6 is formed at a position corresponding to each LED 1 on the light source substrate 3.
  • one concave portion 6 is provided for one LED 1, but this concave portion 6 is a horizontal direction of the light guide plate 2 (a direction perpendicular to the optical axis of the LED 1 and in the horizontal direction of FIG. 1). ) May be formed by extending continuously.
  • a rib for partitioning the LEDs 1 may be provided inside the groove and between the LEDs 1. If the rib is provided, the luminance near the rib may be lowered. In this case, the rib may be appropriately provided with a slope shape or a diffusion surface.
  • the number and arrangement configuration of the light guide plate blocks 2a, 2b, and 2c shown in FIGS. 1 and 2 are merely examples, and are not limited thereto.
  • a plurality of light guide plate blocks are arranged two-dimensionally. May be.
  • the light guide plate 2 is transparent, and is molded from a resin material such as PMMA or polycarbonate.
  • a fine optical pattern may be provided on the surface (light emitting surface and / or back surface).
  • Such an optical pattern may be formed by printing a reflective ink on the surface of the light guide plate 2 or may be provided with prism-shaped or lens-shaped irregularities formed of polygons by, for example, laser processing. Good.
  • the density and size of the unevenness may vary depending on the position of the light exit surface of the light guide plate 2.
  • the pattern may be regularly arranged one-dimensionally or two-dimensionally.
  • a reflection sheet 7 is provided on the back surface of the light guide plate 2 so that light transmitted through the back surface of the light guide plate 2 is reflected and returned to the inside of the light guide plate 2. Thereby, luminance uniformity and emission efficiency can be improved.
  • the reflective sheet to be used may be a reflective sheet having diffusibility or a mirror mirror. When a mirror mirror is used, it becomes easy to give a peak to the light distribution, and if it is a diffuse reflection sheet, the light distribution is wide and the emission efficiency is easily improved. Which is used may be appropriately selected according to the desired optical performance.
  • the LED 1 emits white light, and is mounted on the light source substrate 3 so that its optical axis is in a direction substantially parallel to the light emitting surface or back surface of the light guide plate 2 or the surface of the light source substrate 3. Accordingly, the light emission direction of the LED 1 is the longitudinal direction of the light guide plate 2 (the direction from the left to the right in FIG. 2), as indicated by the arrows in FIG.
  • the LED 1 can be mounted on the light source substrate 3 as it is. In this way, the light emission direction of the LED 1 can be easily matched with the longitudinal direction of the light guide plate 2. For this reason, a side view type LED is used as the LED 1 in this embodiment.
  • an LED is used as the light source, but an LD (laser diode) can also be used.
  • a plurality of light sources having different emission colors such as RGB may be combined. With such a configuration, the emission color can be adjusted.
  • a top-view type LED that emits light in a direction substantially perpendicular to the electrode surface is used, and the light source substrate 3 is arranged so that its optical axis is parallel to the surface of the light source substrate 3. May be implemented. Which type is to be used may be appropriately selected according to the mounting configuration and conditions of the LED on the light source substrate 3.
  • the light source substrate 3 on which the LEDs 1 are mounted is attached to the back surface of the light guide plate 2 via the reflection sheet 7 so that each LED 1 is accommodated in the recess 6 of the light guide plate 2.
  • the reflection sheet 7 is sandwiched and held between the back surface of the light guide plate 2 and the light source substrate 3.
  • the light guide plate 2 and the light source substrate 3 are attached by, for example, inserting a mold pin (not shown) into a hole penetrating the light source substrate 3, the reflection sheet 7, and the light guide plate 2.
  • the light source substrate 3 is fixed to the metal chassis 9 through an insulating sheet (not shown).
  • the light guide plate 2, the light source substrate 3 including the LEDs 1, and the reflection sheet 7 are held by the chassis 9.
  • the mold pin may also penetrate the chassis 9 to couple the light source substrate 3, the reflection sheet 7, and the light guide plate 2.
  • a metal such as aluminum, iron, an alloy, or a plastic material such as PET can be used.
  • the LED 1 housed in the recess 6 of the light guide plate 2 emits light in a direction substantially parallel to the light emitting surface or back surface of the light guide plate 2 or the surface of the light source substrate 3, and this light is incident on one side of the recess 6.
  • the light enters the light guide plate 2 through the surface.
  • a part of the light incident on the light guide plate 2 is transmitted through the light exit surface of the light guide plate 2, and a part of the light travels in the longitudinal direction of the light guide plate 2 while being repeatedly reflected on the light exit surface and the back surface.
  • the light is emitted from the light emission surface according to the shape and characteristics of an optical pattern (not shown) formed on the light emission surface of the light guide plate 2.
  • the light transmitted through the back surface of the light guide plate 2 is reflected by the reflection sheet 7, returns to the light guide plate 2 again, and is emitted from the light exit surface of the light guide plate 2.
  • the light emitted from the light exit surface of the light guide plate 2 is spatially uniformized by the light distribution adjusting sheet 4.
  • a diffusion sheet made of a diffusible material can be used, for example. Thereby, luminance unevenness on the light emitting surface of the lighting device can be reduced, and a high-quality light emission state can be realized.
  • the light distribution adjusting sheet 4 may be configured in combination with a diffusion sheet, a brightness enhancement film such as a prism sheet, and another diffusion plate having a thickness larger than that of the diffusion sheet in order to further increase the diffusibility. .
  • the light transmitted through the light distribution adjusting sheet 4 is irradiated to the liquid crystal panel 5.
  • the liquid crystal panel 5 controls the transmittance for each liquid crystal pixel according to the input video signal, and optically responds to the input video signal by spatially modulating the light from the light distribution adjustment sheet 4 for each liquid crystal pixel.
  • An image (video) is formed.
  • area dimming is performed in which the light intensity in the bright part of the image is increased and the light intensity in the dark part of the image is decreased.
  • a signal processing circuit such as an LSI for area dimming is attached to the rear side of the chassis 9.
  • the LED 1 in the cross-section perpendicular to the light emission surface of the light guide plate 2 and parallel to the optical axis of the LED, the LED 1 is positioned at a position corresponding to the LED 1 or the recess 6 on the light emission surface side of the light guide plate 2.
  • the inclined surface 8 is formed so as to have a shape from the back side of the light guide plate 2 toward the light emitting surface.
  • the inclined surface 8 is formed from the rear surface of the light guide plate 2 on the rear surface (surface opposite to the light emission surface) side of the LED 1 to the light emission surface of the light guide plate 2 positioned at a predetermined distance from the light emission surface of the LED 1. Has been.
  • the angle of the inclined surface 8 is inclined more than the critical angle of the light guide plate with respect to the air when the direction perpendicular to the irradiation surface of the lighting device (light distribution adjusting sheet 4 or light emitting surface of the light guide plate 2) is used as a reference. . Further, as shown in FIG. 1, the inclined surface 8 extends continuously in the arrangement direction of the LEDs 1 (direction perpendicular to the optical axis of the LEDs 1).
  • a strong peak that is, a light spot
  • luminance unevenness tends to appear more prominently as the distance between the light distribution adjusting sheet 4 and the light guide plate 2 is smaller.
  • the inclined surface 8 is provided at a position corresponding to the LED 1 or the recess 6 on the light emitting surface side of the light guide plate 2.
  • the optical action of the inclined surface 8 will be described with reference to FIG.
  • FIG. 3 shows the optical action of the inclined surface 8 and the irradiation intensity distribution of the emitted light for one light guide plate block in this embodiment.
  • the light source board 3 and the chassis 9 are not shown for simplification of illustration.
  • the inclined surface 8 provided at a position corresponding to the LED 1 on the light guide surface 2 of the light guide plate 2 is based on a direction perpendicular to the irradiation surface (light distribution adjustment sheet 4 or the light output surface of the light guide plate 2) of the lighting device. Inclined more than the critical angle based on the material of the light guide plate 2. For this reason, as shown in FIG. 3, the angle ⁇ formed between the light beam directed substantially directly upward from the LED 1 and the inclined surface 8 is larger than the critical angle. A light beam incident from a medium having a higher refractive index to a lower medium at an angle larger than the critical angle has a property of being totally reflected and not transmitted.
  • the light beam reflected from the LED 1 or by the concave portion 6 or the reflection sheet 7 and traveling in a direction substantially perpendicular to the irradiation surface of the illumination device is totally reflected by the inclined surface 8 of the light guide plate 2 as shown in the drawing. 2 in the longitudinal direction and does not pass through the inclined surface 8. Therefore, as shown in the irradiation intensity distribution graph in the upper part of FIG. 3, the luminance is locally increased in the vicinity of the portion immediately above the LED 1 on the irradiation surface of the illumination device, that is, the light spot is suppressed or reduced compared to FIG. 11. Can do. As a result, it is possible to suppress luminance unevenness in which the vicinity of the light emission surface of the LED 1 appears to be bright locally.
  • the light beam directed almost directly above the LED 1 travels in the longitudinal direction of the light guide plate 2 by the inclined surface 8, it can be used as light emitted from the light emitting surface.
  • a light shielding member or the like is provided at a position corresponding to the LED 1 or the concave portion 6 on the light emitting surface of the light guide plate 2, light energy is lost due to light absorption by the light shielding member.
  • the loss does not occur and the light can be used as light emitted from the light emitting surface. Therefore, according to the present embodiment, it is possible to suppress luminance unevenness due to the light spot while improving the light utilization efficiency.
  • a diffusive transmissive sheet may be arranged on the light guide plate 2 as a light distribution adjusting sheet 4 at a predetermined distance, and the light distribution angle of the light from the light guide plate 2 may be dispersed to reduce luminance unevenness. Further, by arranging any one of the reflection sheet and the optical member subjected to the three-dimensional pattern processing as the light distribution adjusting sheet 4 or a combination thereof, the light from the light guide plate 2 is divided into reflected light and transmitted light. The brightness unevenness may be reduced.
  • the concave portion 6 or the reflection sheet 7 and directed almost directly above the LED 1 is configured.
  • a light shielding member may be provided.
  • the inclined surface 8 in the portion corresponding to the LED 1 or the recess 6 of the light guide plate 2 by providing the inclined surface 8 in the portion corresponding to the LED 1 or the recess 6 of the light guide plate 2, the light directed toward the vicinity of the portion directly above the light emitting surface of the LED 1 is totally reflected.
  • the longitudinal direction (tip direction) of the light guide plate By guiding in the longitudinal direction (tip direction) of the light guide plate, it is possible to locally increase the brightness in the portion immediately above the light emitting surface of the LED 1, that is, to reduce the brightness of the light spot. Therefore, according to the present embodiment, it is possible to provide an illumination device in which luminance unevenness is reduced while improving light utilization efficiency and a liquid crystal display device using the illumination device.
  • the illumination device having the optical action / effect described above can be obtained without a new member such as a light-shielding member, a forming process for adding it, or a processing process.
  • the illumination device having the optical action / effect described above can be obtained.
  • a liquid crystal display device using this can be realized at low cost.
  • the lighting device according to the present embodiment is applied to the backlight of the liquid crystal display device.
  • the present invention is not limited to this, and the present invention is also applicable to, for example, indoor lighting, outdoor lighting, and signboard lighting. Embodiments can be applied.
  • the light guide plate blocks 2a, 2b, and 2c are physically divided.
  • the light guide plate blocks 2a, 2b Two or more or all of 2c may be integrated.
  • a V-shaped groove 81 may be formed at a position corresponding to the LED 1 or the recess 6 on the light emitting surface of the light guide plate 2, thereby forming the inclined surface 8. That is, in this modification, a V-shaped groove 81 having an inclined surface 8 is provided at a position in the vicinity of the LED 1 on the light emitting surface of the light guide plate 2 with integrated blocks.
  • the groove may be U-shaped.
  • the light source board 3 and the chassis 9 are not shown for simplification.
  • the light guide plate block by integrating at least one light guide plate block, it is possible to reduce the number of man-hours for mounting to the chassis 9, and thus it is possible to provide a lighting device that is easy to manufacture. Furthermore, in this modification, by forming the inclined surface 8 with the V-shaped groove 81, when the light guide plate is produced by injection molding, the depression caused by the shrinkage of the light guide plate during cooling after injection molding is suppressed. It becomes possible to do. In the injection molding, when the thickness changes, when the resin cools and hardens, temperature unevenness or shrinkage unevenness may occur and a dent may occur. In order to prevent this, it is desirable that the light guide plate has a shape with little change in thickness.
  • a V-shaped groove 81 is formed at a position corresponding to the LED 1 or the concave portion 6 on the light emitting surface of the light guide plate 2, thereby changing the thickness compared to the light guide plate block of FIGS. 1 and 2. Therefore, it is possible to provide a high quality light guide plate 2 by preventing deformation during manufacture.
  • the V-shaped groove 81 can be easily formed by, for example, providing a projection corresponding to the V-shaped groove 81 in a mold in advance in injection molding.
  • the V-shaped groove 81 may be formed by cutting the surface of the light guide plate 2.
  • the inclined surface 8 formed on the light guide plate 2 is a linear plane.
  • the light exit surface of the light guide plate 2 is orthogonal to the light exit surface.
  • the curved inclined surface 82 is provided at a position corresponding to the LED 1 or the recess 6 on the light emitting surface side of the light guide plate 2.
  • the curved inclined surface 82 has a convex shape toward the light emitting surface side of the light guide plate 2 in the cross section, and the light guide plate on the rear surface (surface opposite to the light emitting surface) of the LED 1.
  • the angle between the line segment connecting the arbitrary point on the curved inclined surface 82 in the cross section and the light emitting surface of the LED 1 and the normal line at the arbitrary point is the critical of the light guide plate 2 with respect to air. It is more than a corner.
  • the light guide plate 2 is composed of a plurality of light guide plate blocks 2a, 2b, and 2c as in the first embodiment, but this is an example.
  • the number and arrangement direction of the light guide plate blocks are not limited to this.
  • FIG. 7 shows an irradiation intensity distribution of the emitted light in one light guide plate block based on the present embodiment.
  • illustration of the light source substrate 3 and the chassis 9 is omitted for simplification of illustration.
  • the substantially true LED 1 as described in the first embodiment is provided.
  • the region that gives the optical action of the light directed upward in the longitudinal direction of the light guide plate 2 is wider than the planar inclined surface.
  • a light beam that is perpendicular or substantially perpendicular to the light emitting surface of the light guide plate 2 from the LED 1 can be reflected by the inclined surface 8.
  • the light beam is emitted from the LED 1.
  • the effect of suppressing the light spot in the vicinity of the light emission surface of the LED 1 on the irradiation surface of the illumination device is larger than that in the first embodiment, as shown in the graph of the irradiation intensity distribution at the top of FIG.
  • this embodiment can also be configured to integrate a plurality of light guide plate blocks 2a, 2b, and 2c as shown in FIG. 8, for example.
  • the light source board 3 and the chassis 9 are not shown for the sake of simplicity.
  • a curved V-shaped groove 83 having a curved surface 82 as a surface closer to the LED 1 is provided on the light emitting surface of the light guide plate 2. According to such a configuration, it is possible to have the effect of the second embodiment that the productivity is further improved in addition to the effect of the present embodiment.
  • the shape of the cross section of the curved inclined surface 82 may be a parabolic inclined surface 84 having a paraboloid having a focal point near the light emitting surface of the LED 1 as shown in FIG. 9 also omits the illustration of the light source board 3 and the chassis 9 for simplification of illustration.
  • the light beam from the LED 1 emitted from the focal position of the paraboloid is reflected by the inclined surface 84 of the paraboloid, and is emitted substantially parallel to the reflection sheet 7 or the chassis 3 as shown in the figure. It becomes easy to reach far away from the light guide plate 2.
  • a lighting device can be provided.
  • any of the above examples has an effect of suppressing the increase in luminance (light spot) immediately above the light emitting surface of the LED 1, but was partially printed with ink having low reflectivity or transparency to further suppress the increase in luminance.
  • a transmissive optical sheet may be provided on the light guide plate 2.
  • the brightness suppression effect is high when printed directly above the LED 1. Thereby, luminance uniformity can be further improved.
  • this invention is not limited to the above-mentioned Example, Various modifications are included.
  • the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those including all the components of the embodiments.
  • a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Planar Illumination Modules (AREA)

Abstract

In an illumination device whereby light from an LED is converted to a planar light source by a light guide plate, there is disclosed a technique for making it possible to obtain uniform brightness distribution with increased efficiency of utilisation of the light and reduced brightness unevenness. The illumination device comprises: a plurality of LEDs (1) acting as a light source; a light guide plate (2) for emitting the light from these LEDs (1) as planar light; and an optical distribution adjustment sheet (4) arranged on the optical emission side of this light guide plate. The optic axis of the LEDs (1) is substantially parallel with the optical emission face or back face of the light guide plate (2) and a recess (6) for accommodating the LEDs (1) is provided on the back face side of the light guide plate (2). An inclined face (8) is provided in a position corresponding to the recess (6) or LEDs (1) of the optical emission face of the light guide plate (2). The angle of this inclined face (8) is at least the critical angle of the light guide plate (2) with respect to air, taking the direction perpendicular to the optical emission face of the light guide plate (2) as a reference.

Description

照明装置およびそれを用いた液晶表示装置LIGHTING DEVICE AND LIQUID CRYSTAL DISPLAY DEVICE USING THE SAME
　本発明は、照明装置、及びこれをバックライトとして用いた液晶表示装置に関する。 The present invention relates to an illumination device and a liquid crystal display device using the same as a backlight.
　近年の省電力要求に対応するため、液晶表示装置に用いられるバックライトユニットにおいても消費電力の低減が求められている。そのため、バックライトユニットの光源として、従来のＣＣＦＬ等の蛍光管に代えて、発光効率が高く、かつ応答性が高い（つまりバックライトの光強度を局所的或いは部分的に制御するエリア制御が容易な）発光ダイオード(ＬＥＤ：Light Emitting Diode)が用いられている。 In order to meet the recent power saving demand, reduction of power consumption is also required in backlight units used in liquid crystal display devices. Therefore, as a light source of the backlight unit, instead of a conventional fluorescent tube such as CCFL, the luminous efficiency is high and the response is high (that is, the area control for locally or partially controlling the light intensity of the backlight is easy. A light emitting diode (LED: Light Emitting Diode) is used.
　ＬＥＤを光源として使用するバックライトユニットは、主として直下型、エッジライト型（サイドライト型とも呼ばれる）があり、エッジライト型は、ＬＥＤ等の点状光を透明樹脂で構成された平板状の導光板により面状光にして液晶パネルへ照射する構成であるため、映像表示装置の薄型化（奥行き寸法の低減）に有利である。 Backlight units that use LEDs as light sources are mainly of direct type and edge light type (also called side light type). Edge light type is a flat light guide made of transparent resin for point light such as LEDs. Since it is the structure which irradiates a liquid crystal panel by making it planar light with an optical plate, it is advantageous to thickness reduction (reduction of a depth dimension) of a video display apparatus.
　このような導光板を用いたバックライト装置の従来技術として、例えば特許文献１に記載のものが知られている。特許文献１は、導光板の底面に水平方向を長手方向とした凹部を垂直方向に複数設け、それぞれの凹部にサイドエミッション型ＬＥＤを複数格納し、ＬＥＤからの光を導光板内部で反射して液晶パネル側へ出射することを開示している。 As a conventional technology of a backlight device using such a light guide plate, for example, the one described in Patent Document 1 is known. In Patent Document 1, a plurality of concave portions having a horizontal direction as a longitudinal direction are provided on the bottom surface of the light guide plate in the vertical direction, a plurality of side emission LEDs are stored in the respective concave portions, and light from the LEDs is reflected inside the light guide plate. It discloses that the light is emitted to the liquid crystal panel side.
　また導光板を用いたバックライト装置においては、導光板の光源近傍部分（光入射部付近）が他の部分に比べ光の強度が局所的に大きくなるという、輝度むらが発生する。かかる輝度むらを低減するための従来技術として、例えば特許文献２～３に記載のように、導光板表面の光源近傍部分に遮光部材や光反射吸収部材を設けることが知られている。 Also, in the backlight device using the light guide plate, unevenness in luminance occurs in which the light intensity in the vicinity of the light source (near the light incident portion) of the light guide plate is locally higher than the other portions. As a conventional technique for reducing such luminance unevenness, for example, as disclosed in Patent Documents 2 to 3, it is known to provide a light shielding member and a light reflection / absorption member near the light source on the surface of the light guide plate.
特開２００６－２３６７０１号公報JP 2006-236701 A 特開２００５－１１７０２３号公報Japanese Patent Laid-Open No. 2005-117023 特開２００３－２４２８１７号広報Japanese Laid-Open Patent Publication No. 2003-242817
　上記特許文献１ではＬＥＤとしてサイドエミッション型（サイドビュー型）ＬＥＤを使用しているが、サイドビュー型のＬＥＤにおいても、ＬＥＤの直上方向、すなわちサイドビュー型ＬＥＤの光軸方向と直交する方向で液晶パネル側に向かう光が存在する。例えば、ＬＥＤのパッケージを透過した光や凹部の内壁面、または導光板の背面側に配置された反射シートで反射した光などである。このような光により、導光板を液晶パネル側（映像観察側）から見た場合、導光板の光出射面の、ＬＥＤの配置位置或いは凹部の形成位置と対応した箇所に点状の光スポットまたは輝線が生じ、これが輝度むらとして視認される。上記特許文献はこの点については考慮されていない。 In the above Patent Document 1, a side emission type (side view type) LED is used as the LED. However, even in a side view type LED, a direction directly above the LED, that is, a direction orthogonal to the optical axis direction of the side view type LED. There is light traveling toward the liquid crystal panel. For example, the light transmitted through the LED package, the light reflected from the inner wall surface of the recess, or the reflection sheet disposed on the back side of the light guide plate. With such light, when the light guide plate is viewed from the liquid crystal panel side (image viewing side), a spot-like light spot or a spot on the light emission surface of the light guide plate corresponding to the LED placement position or the recess formation position Bright lines are generated and are visually recognized as uneven brightness. The above-mentioned patent document does not consider this point.
　また、上記の光スポットまたは輝線を視覚的に目立たなくするために、例えば特許文献２または３のように導光板表面の光源近傍部分に遮光部材や光反射吸収部材を設けた場合は、遮光部材や光反射吸収部材で光エネルギーが吸収されることとなるため光の利用効率が低下する。また、当該部材の形成・加工工程及び部品点数が増加するため、コストの上昇を生じることとなる。 Further, in order to make the above-mentioned light spot or bright line visually inconspicuous, for example, when a light shielding member or a light reflection / absorption member is provided in the vicinity of the light source on the surface of the light guide plate as in Patent Document 2 or 3, the light shielding member In addition, since light energy is absorbed by the light reflection / absorption member, the light use efficiency decreases. In addition, since the formation and processing steps of the member and the number of parts increase, the cost increases.
　本発明は、上記従来技術の課題に鑑みて為されたものであり、光の利用効率を高めつつ、輝度むらを低減して均一な輝度分布を得ることが可能な技術を提供するものである。 The present invention has been made in view of the above-described problems of the prior art, and provides a technique capable of reducing luminance unevenness and obtaining a uniform luminance distribution while improving light utilization efficiency. .
　本発明は、特許請求の範囲に記載された構成を特徴とするものである。その一例を挙げるならば、本発明は、複数の光源と、該光源からの光を面状光として出射するための導光板と、該導光板の光出射側に配置された配光調整シートとを備えた照明装置において、前記光源の光軸は、前記導光板の光出射面またはその背面と略平行であり、前記導光板の背面側に前記光源を収納するための凹部が設けられ、前記導光板の光出射面の、前記凹部または前記光源と対応する位置に傾斜面が設けられ、前記傾斜面は前記ＬＥＤの光軸方向に従って前記導光板の背面から光出射面へ向かうように形成されており、前記傾斜面の角度が、前記導光板の光出射面と垂直な方向を基準にしたとき、空気に対する前記導光板の臨界角以上に傾いていることを特徴とする。 The present invention is characterized by the structure described in the claims. As an example, the present invention relates to a plurality of light sources, a light guide plate for emitting light from the light sources as planar light, and a light distribution adjusting sheet disposed on the light emission side of the light guide plate. The optical axis of the light source is substantially parallel to the light emitting surface of the light guide plate or the back surface thereof, and a recess for storing the light source is provided on the back side of the light guide plate, An inclined surface is provided at a position corresponding to the concave portion or the light source on the light emitting surface of the light guide plate, and the inclined surface is formed so as to go from the back surface of the light guide plate to the light emitting surface according to the optical axis direction of the LED. The angle of the inclined surface is inclined more than a critical angle of the light guide plate with respect to air when the direction perpendicular to the light emitting surface of the light guide plate is used as a reference.
　本発明は、装置の薄型化に有利で、かつ高輝度、輝度均一性が高く、エリア調光を適用するのに好適な照明装置及びそれを用いた液晶表示装置を提供することができる。 The present invention can provide an illumination device that is advantageous for thinning the device, has high luminance and high luminance uniformity, and is suitable for applying area dimming, and a liquid crystal display device using the same.
　上記した以外の本発明の構成及び効果は、以下の実施形態の説明により明らかにされる。 The configuration and effects of the present invention other than those described above will become apparent from the following description of the embodiments.
本発明の第１実施例に係る照明装置の俯瞰図である。It is an overhead view of the illuminating device which concerns on 1st Example of this invention. 本発明の第１実施例に係る照明装置の側面図である。It is a side view of the illuminating device which concerns on 1st Example of this invention. 第１実施例による光学的作用及び照射強度分布を示す図である。It is a figure which shows the optical effect | action and irradiation intensity distribution by 1st Example. 第２実施例の変形例に係る照明装置の側面図を示す図である。It is a figure which shows the side view of the illuminating device which concerns on the modification of 2nd Example. 本発明の第２実施例に係る照明装置の俯瞰図である。It is an overhead view of the illuminating device which concerns on 2nd Example of this invention. 本発明の第２実施例に係る照明装置の側面図である。It is a side view of the illuminating device which concerns on 2nd Example of this invention. 第２実施例による光学的作用及び照射強度分布を示す図。The figure which shows the optical effect | action and irradiation intensity distribution by 2nd Example. 第２実施例の変形例を示す図である。It is a figure which shows the modification of 2nd Example. 第２実施例の更に別の変形例を示す図である。It is a figure which shows another modification of 2nd Example. 第１実施例において傾斜面８が無い場合の照射強度分布を示す図。The figure which shows irradiation intensity distribution when there is no inclined surface 8 in 1st Example.
　以下、本発明の実施形態について、添付の図面を参照して説明する。尚、各図または各実施例において、同一の構成、機能または作用を有する要素には同じ番号を付し、重複した説明を省略するものとする。 Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In each drawing or each embodiment, elements having the same configuration, function, or action are denoted by the same reference numerals, and redundant description is omitted.
　まず図１～図４を用いて、本発明の第１実施例の構成を説明する。図１及び図２に示されるように、本実施例に係る液晶表示装置は、光源としての複数のＬＥＤ（Light Emitting Diode）１と、該ＬＥＤ１からの光を面状光にして液晶パネル５側へ出射するための平板形状を為す導光板２と、複数のＬＥＤ１、及びＬＥＤ１に電流を供給するためのドライバ等の電子部品（図示しない）が実装された光源基板３と、導光板２の光出射面（液晶パネル５と対向する面）側に対して所定距離間隔を以って設けられた配光調整シート４と、該配光調整シート４を透過した光が照射される液晶パネル５と、導光板２の背面側に設けられた反射シート７と、シャーシ９とを有する。ここで、ＬＥＤ１、導光板２、光源基板３、配光調整シート４及び反射シート７は、本実施例に係る液晶表示装置の照明装置、すなわちバックライト装置を構成する。この照明装置は、更にシャーシ９を含んでもよい。 First, the configuration of the first embodiment of the present invention will be described with reference to FIGS. As shown in FIGS. 1 and 2, the liquid crystal display device according to the present embodiment includes a plurality of LEDs (Light Emitting Diode) 1 serving as light sources and the liquid crystal panel 5 side by converting the light from the LEDs 1 into planar light. A light guide plate 2 having a flat plate shape for emitting light, a plurality of LEDs 1, a light source substrate 3 on which electronic components (not shown) such as drivers for supplying current to the LEDs 1 are mounted, and light of the light guide plate 2 A light distribution adjusting sheet 4 provided at a predetermined distance from the emission surface (surface facing the liquid crystal panel 5), and a liquid crystal panel 5 irradiated with light transmitted through the light distribution adjusting sheet 4; And a reflection sheet 7 provided on the back side of the light guide plate 2 and a chassis 9. Here, the LED 1, the light guide plate 2, the light source substrate 3, the light distribution adjustment sheet 4, and the reflection sheet 7 constitute an illumination device of the liquid crystal display device according to the present embodiment, that is, a backlight device. The lighting device may further include a chassis 9.
　本実施例において、導光板２は複数の導光板ブロック２ａ、２ｂ、２ｃで構成されており、また各導光板ブロック２ａ、２ｂ、２ｃにはそれぞれ複数（本実施例では４個）のＬＥＤが設けられている。また各導光板ブロック２ａ、２ｂ、２ｃの背面（光出射面と反対側の面であり光源基板３の面と対向する面）側には、図２に示されるようにＬＥＤ１を収納するための凹部６が設けられている。この凹部６は、光源基板３上の各ＬＥＤ１と対応する位置に形成されている。本実施例では、１つのＬＥＤ１に対し１つの凹部６を設けているが、この凹部６は、導光板２の水平方向（ＬＥＤ１の光軸と直交する方向であって、図１の紙面左右方向）に連続的に延びて形成された溝であってもよい。溝の場合は、当該溝の内部であってＬＥＤ１相互間に、ＬＥＤ１間を仕切るためのリブを設けてもよい。リブを設けるとリブ近傍の輝度が低下してしまう可能性があるため、その場合にはリブに適宜斜面形状や拡散面を設けてもよい。 In this embodiment, the light guide plate 2 is composed of a plurality of light guide plate blocks 2a, 2b and 2c, and each of the light guide plate blocks 2a, 2b and 2c has a plurality of (four in this embodiment) LEDs. Is provided. Further, as shown in FIG. 2, the LED 1 is housed on the back surface (surface opposite to the light emission surface and facing the surface of the light source substrate 3) of each light guide plate block 2a, 2b, 2c. A recess 6 is provided. The recess 6 is formed at a position corresponding to each LED 1 on the light source substrate 3. In this embodiment, one concave portion 6 is provided for one LED 1, but this concave portion 6 is a horizontal direction of the light guide plate 2 (a direction perpendicular to the optical axis of the LED 1 and in the horizontal direction of FIG. 1). ) May be formed by extending continuously. In the case of a groove, a rib for partitioning the LEDs 1 may be provided inside the groove and between the LEDs 1. If the rib is provided, the luminance near the rib may be lowered. In this case, the rib may be appropriately provided with a slope shape or a diffusion surface.
　図１及び図２に示された導光板ブロック２ａ、２ｂ、２ｃの数や配置構成はは一例であって、これに限定されるものではなく、例えば複数の導光板ブロックを二次元的に配列してもよい。 The number and arrangement configuration of the light guide plate blocks 2a, 2b, and 2c shown in FIGS. 1 and 2 are merely examples, and are not limited thereto. For example, a plurality of light guide plate blocks are arranged two-dimensionally. May be.
　上記導光板２は透明であり、例えばＰＭＭＡ、ポリカーボネ―トなどの樹脂材料で成型される。所望の空間的な輝度均一性や配光分布に応じて、その表面（光出射面及び／または背面）に微細な光学パターンを設けてもよい。かかる光学パターンは、反射性を持つインクを導光板２の表面に印刷することで形成してもよいし、また多角形で構成されるプリズム状またはレンズ状の凹凸を例えばレーザ加工で設けてもよい。このような構成であれば、導光板２光出射面での空間的な輝度均一性を改善することが可能となる。さらに、上記の凹凸の密度や大きさは、導光板２の光出射面の位置によってが変化していてもよい。また、上記パターンは、1次元または２次元的に規則的に配列されるものであってもよい。 The light guide plate 2 is transparent, and is molded from a resin material such as PMMA or polycarbonate. Depending on the desired spatial luminance uniformity and light distribution, a fine optical pattern may be provided on the surface (light emitting surface and / or back surface). Such an optical pattern may be formed by printing a reflective ink on the surface of the light guide plate 2 or may be provided with prism-shaped or lens-shaped irregularities formed of polygons by, for example, laser processing. Good. With such a configuration, it is possible to improve the spatial luminance uniformity on the light exit surface of the light guide plate 2. Furthermore, the density and size of the unevenness may vary depending on the position of the light exit surface of the light guide plate 2. The pattern may be regularly arranged one-dimensionally or two-dimensionally.
　導光板２の背面には反射シート７が設けられており、導光板２の背面を透過した光を反射して導光板２の内部に戻すようにしている。これにより、輝度均一性及び出射効率を改善できる。使用する反射シートは、拡散性を有する反射シートでもよいし、鏡面ミラーでもよい。鏡面ミラーを用いると配光分布にピークを持たせやすくなり、拡散反射シートであれば、配光分布が広く、出射効率が改善されやすくなる。どちらを用いるかは、所望する光学性能に応じて適宜選択すればよい。 A reflection sheet 7 is provided on the back surface of the light guide plate 2 so that light transmitted through the back surface of the light guide plate 2 is reflected and returned to the inside of the light guide plate 2. Thereby, luminance uniformity and emission efficiency can be improved. The reflective sheet to be used may be a reflective sheet having diffusibility or a mirror mirror. When a mirror mirror is used, it becomes easy to give a peak to the light distribution, and if it is a diffuse reflection sheet, the light distribution is wide and the emission efficiency is easily improved. Which is used may be appropriately selected according to the desired optical performance.
　ＬＥＤ１は白色光を放出するものであり、その光軸が導光板２の光出射面または背面、或いは光源基板３の面とほぼ平行な方向となるように光源基板３に実装されている。従って、ＬＥＤ１の光放出方向は、図２の矢印で示されるように、導光板２の長手方向（図２の紙面左から右の方向）となる。ここで、ＬＥＤ１として、光放出方向が電極面と平行なサイドビュー型のＬＥＤを用いれば、ＬＥＤ１を光源基板３にそのまま実装することができる。このようにすれば容易にＬＥＤ１の光放出方向を導光板２の長手方向と一致させることができる。このため、本実施例ではＬＥＤ１としてサイドビュー型のＬＥＤを用いるものとする。 The LED 1 emits white light, and is mounted on the light source substrate 3 so that its optical axis is in a direction substantially parallel to the light emitting surface or back surface of the light guide plate 2 or the surface of the light source substrate 3. Accordingly, the light emission direction of the LED 1 is the longitudinal direction of the light guide plate 2 (the direction from the left to the right in FIG. 2), as indicated by the arrows in FIG. Here, if a side-view type LED whose light emission direction is parallel to the electrode surface is used as the LED 1, the LED 1 can be mounted on the light source substrate 3 as it is. In this way, the light emission direction of the LED 1 can be easily matched with the longitudinal direction of the light guide plate 2. For this reason, a side view type LED is used as the LED 1 in this embodiment.
　本実施例では、光源としてＬＥＤを使用しているが、ＬＤ（レーザダイオード）を使用することも可能である。光源としてＬＥＤやＬＤを用いる場合、ＲＧＢ等発光色が異なる光源を複数組み合わせて構成していてもよい。このような構成であれば、発光色を調整することができる。またサイドビュー型ＬＥＤに代えて、電極面に対して略垂直な方向に光を放出するトップビュー型のＬＥＤを用い、その光軸が光源基板３の面と平行になるように光源基板３に実装してもよい。どちらの型を使用するかは、光源基板３へのＬＥＤの取り付け構成や条件に合わせて適宜選択すればよい。 In this embodiment, an LED is used as the light source, but an LD (laser diode) can also be used. When an LED or LD is used as the light source, a plurality of light sources having different emission colors such as RGB may be combined. With such a configuration, the emission color can be adjusted. Further, instead of the side-view type LED, a top-view type LED that emits light in a direction substantially perpendicular to the electrode surface is used, and the light source substrate 3 is arranged so that its optical axis is parallel to the surface of the light source substrate 3. May be implemented. Which type is to be used may be appropriately selected according to the mounting configuration and conditions of the LED on the light source substrate 3.
　ＬＥＤ１が実装された光源基板３は、各ＬＥＤ１が導光板２の凹部６に収納されるように、反射シート７を介して導光板２の背面に取り付けられる。これにより導光板２の背面と光源基板３とで反射シート７が挟持され保持される。導光板２と光源基板３の取り付けは、例えば図示しないモールドピンを光源基板３、反射シート７、及び導光板２を貫通する孔に挿入することにより行われる。 The light source substrate 3 on which the LEDs 1 are mounted is attached to the back surface of the light guide plate 2 via the reflection sheet 7 so that each LED 1 is accommodated in the recess 6 of the light guide plate 2. As a result, the reflection sheet 7 is sandwiched and held between the back surface of the light guide plate 2 and the light source substrate 3. The light guide plate 2 and the light source substrate 3 are attached by, for example, inserting a mold pin (not shown) into a hole penetrating the light source substrate 3, the reflection sheet 7, and the light guide plate 2.
　光源基板３は、図示しない絶縁シートを介して金属製のシャーシ９に固定される。これによって、導光板２、ＬＥＤ１を含む光源基板３及び反射シート７がシャーシ９に保持される。上記モールドピンは、シャーシ９も貫通して光源基板３、反射シート７、及び導光板２を結合するようにしてもよい。また、シャーシ９の材質は、例えば、アルミニウムや鉄、合金などの金属、またはＰＥＴなどのプラスチック材料などを使用することができる。 The light source substrate 3 is fixed to the metal chassis 9 through an insulating sheet (not shown). As a result, the light guide plate 2, the light source substrate 3 including the LEDs 1, and the reflection sheet 7 are held by the chassis 9. The mold pin may also penetrate the chassis 9 to couple the light source substrate 3, the reflection sheet 7, and the light guide plate 2. As the material of the chassis 9, for example, a metal such as aluminum, iron, an alloy, or a plastic material such as PET can be used.
　導光板２の凹部６に収納されたＬＥＤ１は、導光板２の光出射面または背面或いは光源基板３の面と略平行は方向に光を放出し、この光は凹部６の一側面である入射面を通して導光板２に入射される。導光板２へ入射された光は、一部は導光板２の光出射面を透過して出射し、一部は光出射面と背面で反射を繰り返しながら導光板２の長手方向に進行し、導光板２の光出射面に形成された図示しない光学パターンの形状や特性に応じて光出射面から出射される。導光板２の背面を透過した光は反射シート７で反射されて再び導光板２に戻り、導光板２の光出射面から出射される。 The LED 1 housed in the recess 6 of the light guide plate 2 emits light in a direction substantially parallel to the light emitting surface or back surface of the light guide plate 2 or the surface of the light source substrate 3, and this light is incident on one side of the recess 6. The light enters the light guide plate 2 through the surface. A part of the light incident on the light guide plate 2 is transmitted through the light exit surface of the light guide plate 2, and a part of the light travels in the longitudinal direction of the light guide plate 2 while being repeatedly reflected on the light exit surface and the back surface. The light is emitted from the light emission surface according to the shape and characteristics of an optical pattern (not shown) formed on the light emission surface of the light guide plate 2. The light transmitted through the back surface of the light guide plate 2 is reflected by the reflection sheet 7, returns to the light guide plate 2 again, and is emitted from the light exit surface of the light guide plate 2.
　導光板２の光出射面から出射された光は、配光調整シート４によって空間的に均一化される。この配光調整シート４は、例えば拡散性の材質で構成されている拡散シートを用いることができる。これにより照明装置の発光面における輝度ムラを低減し、高品位な発光状態を実現できる。また、配光調整シート４は、拡散シートと、プリズムシートなどの輝度向上フィルム、より拡散性を増すために、拡散シートよりも厚みを有する別の拡散板等と組み合わせて構成されていてもよい。 The light emitted from the light exit surface of the light guide plate 2 is spatially uniformized by the light distribution adjusting sheet 4. As the light distribution adjustment sheet 4, a diffusion sheet made of a diffusible material can be used, for example. Thereby, luminance unevenness on the light emitting surface of the lighting device can be reduced, and a high-quality light emission state can be realized. Further, the light distribution adjusting sheet 4 may be configured in combination with a diffusion sheet, a brightness enhancement film such as a prism sheet, and another diffusion plate having a thickness larger than that of the diffusion sheet in order to further increase the diffusibility. .
　配光調整シート４を透過した光は、液晶パネル５に照射される。液晶パネル５は、入力された映像信号に応じて液晶画素毎に透過率を制御し、配光調整シート４からの光を液晶画素毎に空間的に変調することにより入力映像信号に応じた光学像（映像）を形成する。 The light transmitted through the light distribution adjusting sheet 4 is irradiated to the liquid crystal panel 5. The liquid crystal panel 5 controls the transmittance for each liquid crystal pixel according to the input video signal, and optically responds to the input video signal by spatially modulating the light from the light distribution adjustment sheet 4 for each liquid crystal pixel. An image (video) is formed.
　各導光板ブロック２ａ、２ｂ、２ｃに対応するＬＥＤ１のグループ、または各導光板ブロック２ａ、２ｂ、２ｃを更に複数のエリアに分割したときの各エリアに対応する１または複数のＬＥＤ１は、各導光板ブロック２ａ、２ｂ、２ｃまたは各エリアに対応する液晶パネル５の領域に供給される映像信号の輝度に応じて個別に制御される。これにより、映像の明るい部分の光強度を強く、映像の暗い部分の光強度を弱くする、いわゆるエリア調光が実行される。尚、エリア調光ためのＬＳＩ等の信号処理回路は、シャーシ９の背面側に取り付けられる。 The group of LEDs 1 corresponding to each light guide plate block 2a, 2b, 2c, or one or more LEDs 1 corresponding to each area when each light guide plate block 2a, 2b, 2c is further divided into a plurality of areas, It is individually controlled according to the luminance of the video signal supplied to the optical plate blocks 2a, 2b, 2c or the area of the liquid crystal panel 5 corresponding to each area. Thus, so-called area dimming is performed in which the light intensity in the bright part of the image is increased and the light intensity in the dark part of the image is decreased. Note that a signal processing circuit such as an LSI for area dimming is attached to the rear side of the chassis 9.
　本実施例は、上記構成において、導光板２の光出射面側のＬＥＤ１または凹部６に対応する位置に、導光板２の光出射面と直交しかつＬＥＤの光軸と平行な断面において、ＬＥＤ１の光軸方向（図２矢印の方向）に従って導光板２の背面側から光出射面に向かうような形状を為す傾斜面８を形成したことを特徴とするものである。この傾斜面８は、ＬＥＤ１の後面（光放出面と反対側の面）側の導光板２背面から、ＬＥＤ１の光放出面よりも所定距離先に位置する導光板２光出射面に渡って形成されている。そして、傾斜面８の角度は、照明装置の照射面（配光調整シート４または導光板２の光出射面）に垂直な方向を基準にしたとき、空気に対する導光板の臨界角以上傾いている。また傾斜面８は、図１に示されるようにＬＥＤ１の配列方向（ＬＥＤ１の光軸と直交する方向）に延びて連続的に形成されている。 In this embodiment, in the cross-section perpendicular to the light emission surface of the light guide plate 2 and parallel to the optical axis of the LED, the LED 1 is positioned at a position corresponding to the LED 1 or the recess 6 on the light emission surface side of the light guide plate 2. According to the optical axis direction (the direction of the arrow in FIG. 2), the inclined surface 8 is formed so as to have a shape from the back side of the light guide plate 2 toward the light emitting surface. The inclined surface 8 is formed from the rear surface of the light guide plate 2 on the rear surface (surface opposite to the light emission surface) side of the LED 1 to the light emission surface of the light guide plate 2 positioned at a predetermined distance from the light emission surface of the LED 1. Has been. And the angle of the inclined surface 8 is inclined more than the critical angle of the light guide plate with respect to the air when the direction perpendicular to the irradiation surface of the lighting device (light distribution adjusting sheet 4 or light emitting surface of the light guide plate 2) is used as a reference. . Further, as shown in FIG. 1, the inclined surface 8 extends continuously in the arrangement direction of the LEDs 1 (direction perpendicular to the optical axis of the LEDs 1).
　ここで、図１及び図２において傾斜面８が無い構成、すなわち導光板２の光出射面が一様に平面である場合の問題について図１０を参照して説明する。 Here, the problem in the case where the inclined surface 8 is not present in FIGS. 1 and 2, that is, the light emission surface of the light guide plate 2 is uniformly flat will be described with reference to FIG.
　図１０に示すように、ＬＥＤ１から出射した光線の中には、ＬＥＤ１から導光板２の光出射面に向かって略垂直に出射し、導光板２を透過する光線が存在する。また凹部９の内壁または反射シート７で反射して上部へ向かう光線も存在する。これらの光線はＬＥＤ１の光放出面の直上部分近傍に集中されることから、当該ＬＥＤ１の光放出面の直上部分は、照射装置の照射面において照度が高くなる傾向にある。つまり、照明装置の照射面上においてＬＥＤ１の光放出面の直上部分で強いピーク、すなわち光スポットが発生し、これが輝度ムラとして見えてしまう。かかる輝度ムラは、配光調整シート４と導光板２との距離が小さいほど顕著に現れる傾向にある。 As shown in FIG. 10, among the light beams emitted from the LED 1, there are light beams that are emitted substantially perpendicularly from the LED 1 toward the light emission surface of the light guide plate 2 and transmitted through the light guide plate 2. There is also a light beam that is reflected by the inner wall of the recess 9 or the reflection sheet 7 and travels upward. Since these light rays are concentrated in the vicinity of the portion immediately above the light emitting surface of the LED 1, the portion directly above the light emitting surface of the LED 1 tends to have high illuminance on the irradiation surface of the irradiation device. That is, a strong peak, that is, a light spot, is generated on the irradiation surface of the illumination device at a portion directly above the light emission surface of the LED 1, and this appears as luminance unevenness. Such luminance unevenness tends to appear more prominently as the distance between the light distribution adjusting sheet 4 and the light guide plate 2 is smaller.
　これに対し本実施例では、図１及び図２に示されるように、導光板２の光出射面側のＬＥＤ１または凹部６に対応する位置に傾斜面８を設けている。かかる傾斜面８の光学作用を図３を用いて説明する。図３は、本実施例における傾斜面８の光学的作用と導光板ブロック１個分の出射光の照射強度分布を示している。図３では図示の簡略化のために光源基板３及びシャーシ９の図示を省略している。 In contrast, in this embodiment, as shown in FIGS. 1 and 2, the inclined surface 8 is provided at a position corresponding to the LED 1 or the recess 6 on the light emitting surface side of the light guide plate 2. The optical action of the inclined surface 8 will be described with reference to FIG. FIG. 3 shows the optical action of the inclined surface 8 and the irradiation intensity distribution of the emitted light for one light guide plate block in this embodiment. In FIG. 3, the light source board 3 and the chassis 9 are not shown for simplification of illustration.
　導光板２光出射面のＬＥＤ１と対応する位置に設けられた傾斜面８は、照明装置の照射面（配光調整シート４または導光板２の光出射面）に垂直な方向を基準にしたとき、導光板２の材質に基づく臨界角以上に傾いている。このため、図３に示されるように、ＬＥＤ１からほぼ真上方向に向かう光線と傾斜面８とがなす角度θは臨界角よりも大きくなる。臨界角よりも大きな角度で屈折率が高い方の媒質から低い方の媒質へ向かって入射した光線は、全反射して透過しない性質がある。つまり、ＬＥＤ１から、または凹部６或いは反射シート７で反射して照明装置の照射面にほぼ垂直な方向に向かう光線は、図示されるように導光板２の傾斜面８で全反射されて導光板２の長手方向に進行し、傾斜面８を透過しない。そのため、図３上部にある照射強度分布グラフに示されるように、照明装置の照射面のＬＥＤ１直上部分近傍で輝度が局所的に高くなること、すなわち光スポットを図１１に比べ抑制または緩和することができる。その結果、ＬＥＤ１の光放出面近傍が局所的に明るく見えるという輝度ムラを抑制することができる。 The inclined surface 8 provided at a position corresponding to the LED 1 on the light guide surface 2 of the light guide plate 2 is based on a direction perpendicular to the irradiation surface (light distribution adjustment sheet 4 or the light output surface of the light guide plate 2) of the lighting device. Inclined more than the critical angle based on the material of the light guide plate 2. For this reason, as shown in FIG. 3, the angle θ formed between the light beam directed substantially directly upward from the LED 1 and the inclined surface 8 is larger than the critical angle. A light beam incident from a medium having a higher refractive index to a lower medium at an angle larger than the critical angle has a property of being totally reflected and not transmitted. That is, the light beam reflected from the LED 1 or by the concave portion 6 or the reflection sheet 7 and traveling in a direction substantially perpendicular to the irradiation surface of the illumination device is totally reflected by the inclined surface 8 of the light guide plate 2 as shown in the drawing. 2 in the longitudinal direction and does not pass through the inclined surface 8. Therefore, as shown in the irradiation intensity distribution graph in the upper part of FIG. 3, the luminance is locally increased in the vicinity of the portion immediately above the LED 1 on the irradiation surface of the illumination device, that is, the light spot is suppressed or reduced compared to FIG. 11. Can do. As a result, it is possible to suppress luminance unevenness in which the vicinity of the light emission surface of the LED 1 appears to be bright locally.
　更に、ＬＥＤ１のほぼ真上方向に向かう光線は傾斜面８によって導光板２の長手方向に進行するため、光出射面から出射する光として利用することが出来る。光スポットを目立たなくするために、導光板２光出射面のＬＥＤ１や凹部６と対応する位置に遮光部材等を設けた場合は、当該遮光部材での光の吸収による光エネルギーの損失が生じるが、本実施例では当該損失が生じず、かつ光出射面から出射する光として利用することができる。従って、本実施例によれば、光の利用効率を向上させつつも光スポットによる輝度ムラを抑制することが可能となる。 Furthermore, since the light beam directed almost directly above the LED 1 travels in the longitudinal direction of the light guide plate 2 by the inclined surface 8, it can be used as light emitted from the light emitting surface. In order to make the light spot inconspicuous, when a light shielding member or the like is provided at a position corresponding to the LED 1 or the concave portion 6 on the light emitting surface of the light guide plate 2, light energy is lost due to light absorption by the light shielding member. In this embodiment, the loss does not occur and the light can be used as light emitted from the light emitting surface. Therefore, according to the present embodiment, it is possible to suppress luminance unevenness due to the light spot while improving the light utilization efficiency.
　さらに、配光調整シート４として拡散性の透過シートを導光板２の上に所定距離離して配置し、導光板２からの光を配光角度を分散させて輝度ムラ低減を図ってもよい。また、配光調整シート４として反射シートや立体的なパターン加工を施した光学部材のいずれか又はこれらの組合せをを配置し、導光板２からの光を反射光と透過光とに分けることで、輝度ムラ低減を図ってもよい。 Furthermore, a diffusive transmissive sheet may be arranged on the light guide plate 2 as a light distribution adjusting sheet 4 at a predetermined distance, and the light distribution angle of the light from the light guide plate 2 may be dispersed to reduce luminance unevenness. Further, by arranging any one of the reflection sheet and the optical member subjected to the three-dimensional pattern processing as the light distribution adjusting sheet 4 or a combination thereof, the light from the light guide plate 2 is divided into reflected light and transmitted light. The brightness unevenness may be reduced.
　また、傾斜面８の各ＬＥＤ１と対応する位置に、ＬＥＤ１から、または凹部６或いは反射シート７で反射してＬＥＤ１のほぼ直上方向に向かう光を吸収或いは反射するための例えば白色インクで構成された遮光部材を設けてよい。このように構成することにより、光の損失が増加するものの、より一層ＬＥＤ１近傍における光スポットを低減或いは緩和することができる。 Further, at a position corresponding to each LED 1 on the inclined surface 8, for example, white ink for absorbing or reflecting light reflected from the LED 1, the concave portion 6 or the reflection sheet 7 and directed almost directly above the LED 1 is configured. A light shielding member may be provided. With this configuration, although the light loss increases, the light spot in the vicinity of the LED 1 can be further reduced or alleviated.
　以上のように、本実施例によれば、導光板２のＬＥＤ１または凹部６と対応する部分に傾斜面８を設けることで、ＬＥＤ１の光放出面の直上部分近傍に向かう光を全反射して導光板の長手方向（先端方向）に導くことで、ＬＥＤ１の光放出面の直上部分における局所的な高輝度化、すなわち光スポットの輝度を低減できる。よって、本実施例によれば、光の利用効率を高めつつも輝度むらが低減された照明装置とこれを用いた液晶表示装置を提供することができる。また、そのような光学的作用・効果を、遮光部材などの新たな部材やそれを付加するための形成工程や加工工程なしに得ることができるので、上記光学的作用・効果を有する照明装置とこれを用いた液晶表示装置を、低コストで実現することができる。 As described above, according to the present embodiment, by providing the inclined surface 8 in the portion corresponding to the LED 1 or the recess 6 of the light guide plate 2, the light directed toward the vicinity of the portion directly above the light emitting surface of the LED 1 is totally reflected. By guiding in the longitudinal direction (tip direction) of the light guide plate, it is possible to locally increase the brightness in the portion immediately above the light emitting surface of the LED 1, that is, to reduce the brightness of the light spot. Therefore, according to the present embodiment, it is possible to provide an illumination device in which luminance unevenness is reduced while improving light utilization efficiency and a liquid crystal display device using the illumination device. In addition, since such an optical action / effect can be obtained without a new member such as a light-shielding member, a forming process for adding it, or a processing process, the illumination device having the optical action / effect described above can be obtained. A liquid crystal display device using this can be realized at low cost.
　上記おいては、液晶表示装置のバックライトに本実施例に係る照明装置を適用した例を説明したが、これに限られるものではなく、例えば室内照明や室外照明、看板の照明などにも本実施例を適用することができる。 In the above, the example in which the lighting device according to the present embodiment is applied to the backlight of the liquid crystal display device has been described. However, the present invention is not limited to this, and the present invention is also applicable to, for example, indoor lighting, outdoor lighting, and signboard lighting. Embodiments can be applied.
　また、図１～図３に示した例では導光板ブロック２ａ、２ｂ、２ｃは物理的に分割されているものとしているが、例えば図４に示される変形例ように、導光板ブロック２ａ、２ｂ、２ｃの２つ以上または全てを一体化してもよい。この場合、導光板２の光出射面のＬＥＤ１または凹部６と対応する位置にＶ字状の溝８１を形成し、これにより傾斜面８を形成すればよい。すなわち、この変形例では、ブロックを一体化した導光板２の光出射面に、ＬＥＤ１近傍の位置に傾斜面８を有するＶ字状の溝８１を設けたものである。溝はＵ字状であってもよい。尚、図４でも図示の簡略化のために光源基板３及びシャーシ９の図示を省略している。 In the example shown in FIGS. 1 to 3, the light guide plate blocks 2a, 2b, and 2c are physically divided. However, for example, as in the modification shown in FIG. 4, the light guide plate blocks 2a, 2b Two or more or all of 2c may be integrated. In this case, a V-shaped groove 81 may be formed at a position corresponding to the LED 1 or the recess 6 on the light emitting surface of the light guide plate 2, thereby forming the inclined surface 8. That is, in this modification, a V-shaped groove 81 having an inclined surface 8 is provided at a position in the vicinity of the LED 1 on the light emitting surface of the light guide plate 2 with integrated blocks. The groove may be U-shaped. In FIG. 4, the light source board 3 and the chassis 9 are not shown for simplification.
　このように、少なくとも１つ以上の導光板ブロックを一体化することにより、シャーシ９への取り付け工数を削減することができるため、製造しやすい照明装置を提供できる。さらに、この変形例では、Ｖ字状の溝８１により傾斜面８を形成することによって、射出成型で導光板を作成する場合において、射出成型後の冷却時に導光板の収縮により発生する凹みを抑制することが可能となる。射出成型では、厚みが変化すると、樹脂が冷却して固まる際に温度ムラや収縮ムラが発生して凹みが発生する可能性がある。これを防ぐためには、導光板の厚みの変化が少ない形状にすることが望ましい。 Thus, by integrating at least one light guide plate block, it is possible to reduce the number of man-hours for mounting to the chassis 9, and thus it is possible to provide a lighting device that is easy to manufacture. Furthermore, in this modification, by forming the inclined surface 8 with the V-shaped groove 81, when the light guide plate is produced by injection molding, the depression caused by the shrinkage of the light guide plate during cooling after injection molding is suppressed. It becomes possible to do. In the injection molding, when the thickness changes, when the resin cools and hardens, temperature unevenness or shrinkage unevenness may occur and a dent may occur. In order to prevent this, it is desirable that the light guide plate has a shape with little change in thickness.
　この変形例では導光板２の光出射面のＬＥＤ１または凹部６と対応する位置にＶ字状の溝８１を形成することにより、図１や図２の導光板ブロックに比べて厚さの変化を小さく出でき、以って、製造時の変形を防ぎ、高品質な導光板２を提供できる。上記Ｖ字状の溝８１は、たとえば射出成型において、金型に予めＶ字状の溝８１に対応する突起などを設けることにより容易に形成することができる。Ｖ字状の溝８１は、導光板２表面を切削することで形成してもよい。このように、この変形例によれば生産性に優れた照明装置を提供できる。 In this modification, a V-shaped groove 81 is formed at a position corresponding to the LED 1 or the concave portion 6 on the light emitting surface of the light guide plate 2, thereby changing the thickness compared to the light guide plate block of FIGS. 1 and 2. Therefore, it is possible to provide a high quality light guide plate 2 by preventing deformation during manufacture. The V-shaped groove 81 can be easily formed by, for example, providing a projection corresponding to the V-shaped groove 81 in a mold in advance in injection molding. The V-shaped groove 81 may be formed by cutting the surface of the light guide plate 2. Thus, according to this modification, it is possible to provide a lighting device with excellent productivity.
　続いて本発明の第２実施例について図５～図９を参照して説明する。 Subsequently, a second embodiment of the present invention will be described with reference to FIGS.
　第１実施例では、導光板２に形成される傾斜面８を直線的な平面としたが、本実施例では図５及び図６に示されるように、導光板２の光出射面と直交しかつＬＥＤ１の光軸と平行な断面において、曲線としている。すなわち、本実施例では、導光板２の光出射面側のＬＥＤ１または凹部６に対応する位置に曲面状傾斜面８２を設けたものである。この曲面状傾斜面８２は、上記断面において、導光板２の光出射面側に向かって凸の形状を為しており、かつＬＥＤ１の後面（光放出面と反対側の面）側の導光板２背面から、ＬＥＤ１の光放出面よりも所定距離先に位置する導光板２の光出射面に渡って形成されている。そして、上記断面における曲面状傾斜面８２の面上の任意の点とＬＥＤ１の光放出面とを結ぶ線分と、当該任意の点における法線とがなす角度が、空気に対する導光板２の臨界角以上となっている。 In the first embodiment, the inclined surface 8 formed on the light guide plate 2 is a linear plane. However, in this embodiment, as shown in FIGS. 5 and 6, the light exit surface of the light guide plate 2 is orthogonal to the light exit surface. And in the cross section parallel to the optical axis of LED1, it is set as the curve. That is, in this embodiment, the curved inclined surface 82 is provided at a position corresponding to the LED 1 or the recess 6 on the light emitting surface side of the light guide plate 2. The curved inclined surface 82 has a convex shape toward the light emitting surface side of the light guide plate 2 in the cross section, and the light guide plate on the rear surface (surface opposite to the light emitting surface) of the LED 1. 2 formed from the rear surface to the light emitting surface of the light guide plate 2 positioned a predetermined distance ahead of the light emitting surface of the LED 1. The angle between the line segment connecting the arbitrary point on the curved inclined surface 82 in the cross section and the light emitting surface of the LED 1 and the normal line at the arbitrary point is the critical of the light guide plate 2 with respect to air. It is more than a corner.
　本実施例は、図５及び図６に示されるように、第１実施例と同様に導光板２は複数の導光板ブロック２ａ、２ｂ、２ｃにより構成されているが、これは一例であり、導光板ブロックの個数や配列方向はこれに限定されるものではない。 In this embodiment, as shown in FIGS. 5 and 6, the light guide plate 2 is composed of a plurality of light guide plate blocks 2a, 2b, and 2c as in the first embodiment, but this is an example. The number and arrangement direction of the light guide plate blocks are not limited to this.
　本実施例に基づく１つの導光板ブロックにおける出射光の照射強度分布を図７に示す。図７は、図示の簡略化のために光源基板３及びシャーシ９の図示を省略している。 FIG. 7 shows an irradiation intensity distribution of the emitted light in one light guide plate block based on the present embodiment. In FIG. 7, illustration of the light source substrate 3 and the chassis 9 is omitted for simplification of illustration.
　図７に示されるように、導光板２の光出射面側のＬＥＤ１または凹部６に対応する位置に曲面状傾斜面８２を設けることによって、第１実施例で説明したような、ＬＥＤ１のほぼ真上方向に向かう光を導光板２の長手方向に向かう光学作用を与える領域が、平面状の傾斜面に比べ広くなる。第１実施例では、ＬＥＤ１から導光板２の光出射面に対して垂直或いは略垂直に向かう光線を傾斜面８で反射可能であったが、本実施例の構成であれば、ＬＥＤ１から出射する光線のうち、導光板２の光出射面に対して垂直な方向以外にも、該垂直方向に対してある程度の角度を有する光線についても反射可能である。そのため、照明装置の照射面の、ＬＥＤ１の光放出面近傍における光スポットを抑制する効果が、図７上方にある照射強度分布のグラフに示されるように、第１実施例に比べ大きくなる。その結果、第１実施例よりも輝度均一性がより改善された照明装置を提供できる。 As shown in FIG. 7, by providing a curved inclined surface 82 at a position corresponding to the LED 1 or the recess 6 on the light emitting surface side of the light guide plate 2, the substantially true LED 1 as described in the first embodiment is provided. The region that gives the optical action of the light directed upward in the longitudinal direction of the light guide plate 2 is wider than the planar inclined surface. In the first embodiment, a light beam that is perpendicular or substantially perpendicular to the light emitting surface of the light guide plate 2 from the LED 1 can be reflected by the inclined surface 8. However, in the case of the configuration of this embodiment, the light beam is emitted from the LED 1. Of the light rays, in addition to the direction perpendicular to the light exit surface of the light guide plate 2, light rays having a certain angle with respect to the vertical direction can be reflected. Therefore, the effect of suppressing the light spot in the vicinity of the light emission surface of the LED 1 on the irradiation surface of the illumination device is larger than that in the first embodiment, as shown in the graph of the irradiation intensity distribution at the top of FIG. As a result, it is possible to provide an illuminating device with improved luminance uniformity as compared with the first embodiment.
　本実施例も第２実施例と同様に、例えば図８に示されるように複数数の導光板ブロック２ａ、２ｂ、２ｃを一体化した構成とすることも可能である。尚、図８でも図示の簡略化のために光源基板３及びシャーシ９の図示を省略している。この場合、図４に示したものと異なり、導光板２の光出射面に、ＬＥＤ１に近い方の面を曲面８２とした曲面付きＶ字状溝８３を設ける。このような構成によれば、本実施例の効果に、更に生産性を向上させるとの第２実施例の効果を併せ持つことが出来る。 As in the second embodiment, this embodiment can also be configured to integrate a plurality of light guide plate blocks 2a, 2b, and 2c as shown in FIG. 8, for example. In FIG. 8, the light source board 3 and the chassis 9 are not shown for the sake of simplicity. In this case, unlike the case shown in FIG. 4, a curved V-shaped groove 83 having a curved surface 82 as a surface closer to the LED 1 is provided on the light emitting surface of the light guide plate 2. According to such a configuration, it is possible to have the effect of the second embodiment that the productivity is further improved in addition to the effect of the present embodiment.
　更にまた、上記曲面状傾斜面８２の上記断面の形状を、例えば図９に示されるようにＬＥＤ１の光放出面近傍に焦点を持つ放物面を有する方物面傾斜面８４としてもよい。図９も図示の簡略化のために光源基板３及びシャーシ９の図示を省略している。この構成であれば、放物面の焦点位置から出射したＬＥＤ１からの光線は、方物面傾斜面８４で反射し、図示されるように反射シート７或いはシャーシ３に略平行に出射するため、導光板２の遠方に到達しやすくなる。その結果、導光板２の光出射面のうち、ＬＥＤ１の光放出面近傍の部分の輝度を低減し、ＬＥＤ１から遠方の部分を明るく照射する構成を実現することが可能となり、輝度均一性が高い照明装置を提供することができる。 Furthermore, the shape of the cross section of the curved inclined surface 82 may be a parabolic inclined surface 84 having a paraboloid having a focal point near the light emitting surface of the LED 1 as shown in FIG. 9 also omits the illustration of the light source board 3 and the chassis 9 for simplification of illustration. With this configuration, the light beam from the LED 1 emitted from the focal position of the paraboloid is reflected by the inclined surface 84 of the paraboloid, and is emitted substantially parallel to the reflection sheet 7 or the chassis 3 as shown in the figure. It becomes easy to reach far away from the light guide plate 2. As a result, it is possible to reduce the luminance of the light emitting surface of the light guide plate 2 in the vicinity of the light emitting surface of the LED 1 and realize a configuration in which the portion far from the LED 1 is brightly irradiated, and the luminance uniformity is high. A lighting device can be provided.
　上記いずれの実施例もＬＥＤ１の光放出面直上の輝度上昇（光スポット）を抑制する効果があるが、さらに輝度上昇を抑制するため、反射性もしくは透過性の低いインクで部分的に印刷された透過性の光学シートを導光板２の上に設けてもよい。特に、ＬＥＤ１直上に印刷されていると輝度抑制効果が高い。これにより、より一層輝度均一性を改善することができる。 Any of the above examples has an effect of suppressing the increase in luminance (light spot) immediately above the light emitting surface of the LED 1, but was partially printed with ink having low reflectivity or transparency to further suppress the increase in luminance. A transmissive optical sheet may be provided on the light guide plate 2. In particular, the brightness suppression effect is high when printed directly above the LED 1. Thereby, luminance uniformity can be further improved.
　この場合において、いずれかの実施例の構成を採用すれば、インクの光学的性質の仕様緩和を図ることができるメリットもある。 In this case, if any one of the configurations of the embodiments is employed, there is an advantage that the specification of the optical properties of the ink can be relaxed.
　なお、本発明は上記した実施例に限定されるものではなく、様々な変形例が含まれる。例えば、上記した実施例は本発明を分かりやすく説明するために詳細に説明したものであり、必ずしも実施例の全ての構成要素を備えるものに限定されるものではない。また、ある実施例の構成の一部を他の実施例の構成に置き換えることが可能であり、また、ある実施例の構成に他の実施例の構成を加えることも可能である。また、各実施例の構成の一部について、他の構成の追加・削除・置換をすることが可能である。 In addition, this invention is not limited to the above-mentioned Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those including all the components of the embodiments. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.
１…光源、２…導光板、３…シャーシ、４…配光調整シート、５…液晶パネル、６…凹部、７…反射シート、８…傾斜面、９…シャーシ、８１…Ｖ字状溝、８２…曲面状傾斜面、８３…曲面付Ｖ字状溝、８４…放物面傾斜面。 DESCRIPTION OF SYMBOLS 1 ... Light source, 2 ... Light guide plate, 3 ... Chassis, 4 ... Light distribution adjustment sheet, 5 ... Liquid crystal panel, 6 ... Recessed part, 7 ... Reflective sheet, 8 ... Inclined surface, 9 ... Chassis, 81 ... V-shaped groove, 82: curved inclined surface, 83 ... V-shaped groove with curved surface, 84 ... parabolic inclined surface.

Claims (7)

  1. 　光源と、該光源からの光を面状光として出射するための導光板と、該導光板の光出射側に配置された配光調整シートとを備えた照明装置において、
    　前記光源の光軸は、前記導光板の光出射面またはその背面と略平行であり、前記導光板の光出射面と対向する背面側に前記光源を収納するための凹部が設けられ、前記導光板の光出射面の前記凹部または前記光源と対応する位置に傾斜面が設けられ、
    　前記傾斜面は、前記光源の光軸方向に従って前記導光板の背面から光出射面へ向かうように形成されており、前記傾斜面の角度が、前記配光調整シートまたは導光板の光出射面と垂直な方向を基準にしたとき、空気に対する前記導光板の臨界角以上に傾いていることを特徴とする照明装置。     In an illuminating device comprising a light source, a light guide plate for emitting light from the light source as planar light, and a light distribution adjustment sheet disposed on the light emission side of the light guide plate,
    The optical axis of the light source is substantially parallel to the light exit surface of the light guide plate or the back surface thereof, and a recess for housing the light source is provided on the back side facing the light exit surface of the light guide plate. An inclined surface is provided at a position corresponding to the concave portion or the light source of the light exit surface of the light plate,
    The inclined surface is formed so as to go from the back surface of the light guide plate to the light emitting surface according to the optical axis direction of the light source, and the angle of the inclined surface is the light distribution adjusting sheet or the light emitting surface of the light guide plate. A lighting device, wherein the lighting device is inclined more than a critical angle of the light guide plate with respect to air when a vertical direction is used as a reference.
  2. 　請求項１に記載の照明装置において、前記光源がサイドビュー型ＬＥＤであり、該サイドビュー型ＬＥＤの光軸が前記導光板の光出射面またはその背面と平行であることを特徴とする照明装置。 The illumination device according to claim 1, wherein the light source is a side-view type LED, and an optical axis of the side-view type LED is parallel to a light emission surface of the light guide plate or a back surface thereof. .
  3. 　請求項２に記載の照明装置において、前記導光板が複数の導光板ブロックで構成されており、前記各導光板ブロックのそれぞれに前記凹部と、前記傾斜面が設けられていることを特徴とする照明装置。 The lighting device according to claim 2, wherein the light guide plate includes a plurality of light guide plate blocks, and each of the light guide plate blocks is provided with the concave portion and the inclined surface. Lighting device.
  4. 　請求項２に記載の照明装置において、前記導光板の光出射面の前記凹部または前記光源と対応する位置に、前記傾斜面を有する溝が形成されていることを特徴とする照明装置。 3. The illumination device according to claim 2, wherein a groove having the inclined surface is formed at a position corresponding to the concave portion or the light source of the light emitting surface of the light guide plate.
  5. 　請求項２に記載の照明装置において、前記傾斜面が、前記導光板の光出射面側に凸を向けた曲面状傾斜面であり、該曲面状傾斜面の任意の点と前記ＬＥＤの光放出面とを結ぶ線分と、当該任意の点における法線とがなす角度が、空気に対する導光板の臨界角以上とされていることを特徴とする照明装置。 3. The lighting device according to claim 2, wherein the inclined surface is a curved inclined surface having a convex toward the light emitting surface side of the light guide plate, and an arbitrary point of the curved inclined surface and light emission of the LED An illuminating device characterized in that an angle formed by a line segment connecting the surfaces and a normal line at the arbitrary point is equal to or greater than a critical angle of the light guide plate with respect to air.
  6. 　請求項２に記載の照明装置において、前記傾斜面が、前記ＬＥＤの光放出面を焦点とした放物面であることを特徴とする照明装置。 3. The illuminating device according to claim 2, wherein the inclined surface is a paraboloid focusing on the light emitting surface of the LED.
  7. 　請求項１乃至６のいずれかに記載の照明装置と液晶パネルとを有し、該照明装置を前記液晶パネルに光を照射するためのバックライトとして用いたことを特徴とする映像表示装置。 7. An image display device comprising the illumination device according to claim 1 and a liquid crystal panel, wherein the illumination device is used as a backlight for irradiating the liquid crystal panel with light.
PCT/JP2011/005524 2011-09-30 2011-09-30 Illumination device and liquid-crystal display device using this WO2013046276A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09160032A (en) * 1995-12-12 1997-06-20 Omron Corp Illuminator, liquid crystal display device using the illuminator, portable terminal equipment, on board equipment and optical recognition device
JP2001250412A (en) * 2000-03-03 2001-09-14 Rohm Co Ltd Illumination device and liquid crystal display device provided with the same
JP2006252951A (en) * 2005-03-10 2006-09-21 Toyoda Gosei Co Ltd Planar light emitting device
JP2008103301A (en) * 2006-09-21 2008-05-01 Sharp Corp Backlight device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09160032A (en) * 1995-12-12 1997-06-20 Omron Corp Illuminator, liquid crystal display device using the illuminator, portable terminal equipment, on board equipment and optical recognition device
JP2001250412A (en) * 2000-03-03 2001-09-14 Rohm Co Ltd Illumination device and liquid crystal display device provided with the same
JP2006252951A (en) * 2005-03-10 2006-09-21 Toyoda Gosei Co Ltd Planar light emitting device
JP2008103301A (en) * 2006-09-21 2008-05-01 Sharp Corp Backlight device

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