WO2004083948A1 - Source de lumiere plane, lumiere avant et afficheur a cristaux liquides - Google Patents

Source de lumiere plane, lumiere avant et afficheur a cristaux liquides Download PDF

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Publication number
WO2004083948A1
WO2004083948A1 PCT/JP1999/007019 JP9907019W WO2004083948A1 WO 2004083948 A1 WO2004083948 A1 WO 2004083948A1 JP 9907019 W JP9907019 W JP 9907019W WO 2004083948 A1 WO2004083948 A1 WO 2004083948A1
Authority
WO
WIPO (PCT)
Prior art keywords
light
guide plate
light guide
plate
light source
Prior art date
Application number
PCT/JP1999/007019
Other languages
English (en)
Japanese (ja)
Inventor
Hiroshi Wada
Original Assignee
Hiroshi Wada
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hiroshi Wada filed Critical Hiroshi Wada
Priority to US09/622,863 priority Critical patent/US6474824B1/en
Publication of WO2004083948A1 publication Critical patent/WO2004083948A1/fr

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Classifications

    • 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
    • G02B6/0038—Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width 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
    • G02B6/0033—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

  • Planar light emitter front light and liquid crystal device
  • the present invention relates to a planar light emitter, a front light, and a liquid crystal device, and more particularly, to a structure of a planar light emitter suitable for use as a front light of a liquid crystal display device.
  • the transmissive liquid crystal display panel has a backlight so that the display can be viewed in a dark place.However, the backlight consumes a lot of power, and when it is used outside a building during bright daylight. On the contrary, there is a problem that the display becomes difficult to see.
  • a light guide plate is installed in front of the reflective liquid crystal display panel, and light from a light source such as a cold cathode tube placed near the end of the light guide plate is guided into the light guide plate.
  • a liquid crystal display device having a front light which is a planar light-emitting body that allows light to be displayed in a dark place by irradiating light from a light guide plate surface to a liquid crystal display panel. ing.
  • the liquid crystal display panel can be viewed through the light guide plate in the daytime, so that it can be used as a normal reflective liquid crystal display panel. This illuminates the liquid crystal display panel to make the display visible.
  • a linear light source such as a cold-cathode tube is used to introduce light almost uniformly into the light guide plate to illuminate the liquid crystal display panel.
  • a cold cathode tube it is sometimes impossible to use a cold cathode tube from the viewpoints of cost and volume, and there is a problem that the power consumption of the cold cathode tube is too large.
  • a front light 1 using a light guide plate 12 formed by arranging stripe-shaped and triangular cross-sectional convex portions on the surface in a plan view consisting of a gentle slope 12a and a steep slope 12b.
  • 0 in order to increase the effective brightness of the display at the time of lighting, it may be set so that it is viewed from the F direction shown in the figure, which is slightly inclined from the normal to the plate surface of the light guide plate 12.
  • a linear light source such as a cold-cathode tube is used as the light source
  • many bright lines are recognized as horizontal lines as shown in FIG. 6 due to the light leaking from the steep slope 12b.
  • a point light source 13 such as a light emitting diode
  • a linear light source such as a cold cathode tube
  • the present invention is to solve the above problems, and an object of the present invention is to provide a planar light emitter such as a front light which does not deteriorate visibility even when a point light source such as a light emitting diode is used. It is in. Disclosure of the invention
  • Means taken by the present invention to solve the above-mentioned problem is that a light-transmitting light guide configured to emit light propagating inside in a predetermined direction along the plate surface from the plate surface.
  • a light plate, and a light source disposed near an end of the light guide plate for introducing light into the light guide plate in another direction different from the predetermined direction; and a side of the light guide plate on which the light source is disposed.
  • a light emitting element provided at a different end thereof with a reflection layer for reflecting light propagating in the light guide plate toward the other direction in the light guide plate substantially in the predetermined direction. It is.
  • the light introduced into the light guide plate from the light source travels in the light guide plate, is reflected by the reflection plate, becomes light that travels in a substantially predetermined direction, and is emitted from the plate surface of the light guide plate. Since the optical path length from the light source to the emission position can be increased, It is possible to enhance the in-plane uniformity of emitted light when there is directivity, when the shape of the light source is a point light source, or when the distribution of light introduced from the light source to the light guide plate is biased. . Further, when used as a front light arranged on the front side of various display bodies, the distribution of the leaked light leaking to the front side can be alleviated, so that the visibility can be improved.
  • the other direction may be, for example, a direction along the plate surface of the light guide plate, and may be a direction opposite to the predetermined direction.
  • a light scattering layer is disposed between the light guide plate and the reflection layer. Since the light scattering layer is arranged before the reflecting surface, the light is scattered before and after the reflection, so that the in-plane uniformity of the emitted light can be further improved.
  • the light source may have directivity in a light emission direction in the light guide plate, and the light source may be a point light source. The invention is particularly effective.
  • the light source is preferably a light emitting diode.
  • the size and weight of the device incorporating the planar light emitter can be reduced, and the manufacturing cost can be reduced.
  • the light guide plate according to any one of claims 1 to 5, wherein the light guide plate is preferably configured not to emit the light traveling in the other direction from the plate surface before reaching the reflection layer. .
  • the entire optical path length of the light emitted from the plate surface of the light guide plate is reflected from the light source to the reflective layer. Since the distance can be longer than the distance, the in-plane uniformity of the emitted light can be increased.
  • a convex portion or a concave portion having a slope for emitting light from the plate surface is formed on the surface of the light guide plate.
  • the convex portion or the concave portion is formed so as to face the other direction as viewed from inside the light guide plate, and has a gentle angle with respect to the plate surface of the light guide plate. It is preferable that a gentle slope and a steep slope formed so as to face in the predetermined direction when viewed from the inside of the light guide plate and having a steep angle with respect to the plate surface of the light guide plate are provided. In this case, the surface consists of only gentle and steep slopes.
  • the convex portion has a triangular cross section and a stripe shape in a plan view. At this time, if the convex portion is formed on the plate surface opposite to the light emission direction, and if the predetermined direction and the other direction are opposite to each other, the steep slope is the convex portion. On the light source side, the gentle slope is formed on the opposite side to the light source.
  • the light source and the light guide plate are configured as front lights arranged on the front side of the panel surface of the liquid crystal device.
  • Such front lights include those described in claims 9 to 14 as described below.
  • a light guide plate having a light transmitting property configured to emit light propagating inside in a predetermined direction along the plate surface from the plate surface; and the light guide plate disposed near an end of the light guide plate.
  • a light source for introducing light in another direction different from the predetermined direction, wherein the light guide plate is configured to be transparent, and at a different end from the side of the light guide plate on which the light source is arranged.
  • a front light provided with a reflection layer for reflecting light propagating in the light guide plate in the other direction in the light guide plate substantially in the predetermined direction;
  • the light introduced into the light guide plate from the light source propagates in the light guide plate in a predetermined direction, is reflected by the reflection layer, propagates in the other direction, and is emitted from the plate surface of the light guide plate.
  • a light scattering layer is disposed in front of the reflection surface of the reflection layer.
  • the light scattered by the light scattering layer distant from the light source is emitted from the light guide plate.
  • the visibility can be further improved.
  • a large directivity reducing effect can be expected in a region close to the light source as compared with a case where a scattering plate is arranged on the incident surface of the light guide plate in the conventional front light structure.
  • a light scattering plate having a relatively low scattering intensity can be used, and light loss can be reduced.
  • the front light according to claim 9, wherein the light source has directivity in a light emission direction in the light guide plate.
  • the present invention is particularly effective when the light source is a point light source, and the light source is preferably a light emitting diode.
  • the light guide plate is configured not to emit the light traveling in the other direction from the plate surface before reaching the reflection layer. Is particularly effective.
  • a reflection type liquid crystal device having the above-mentioned front lights on the front side of the liquid crystal panel can be configured, and in this case, good visibility can be obtained in a bright place or a dark place.
  • FIG. 1 is a schematic cross-sectional view showing a structure of an embodiment of a planar light-emitting body (front light) according to the present invention.
  • FIG. 2 is a schematic configuration diagram showing a schematic configuration of a liquid crystal display device using the embodiment.
  • FIG. 3 is a partial cross-sectional schematic plan view showing a planar light distribution state of the embodiment.
  • FIG. 4 is a schematic plan view showing a schematic plan configuration of a liquid crystal display device using the same embodiment.
  • FIG. 5 is a schematic cross-sectional view showing a schematic structure of a conventional front light.
  • FIG. 6 is an external view explanatory view showing an appearance when a linear light source is used as a light source in the conventional front light. is there.
  • FIG. 7 is an external explanatory view showing the appearance when a point light source is used as a light source in a conventional front light.
  • FIG. 1 is a schematic cross-sectional view showing a schematic structure of a planar light-emitting body 20 according to the present invention.
  • the present embodiment includes a point light source 21 such as a light emitting diode, a light guide plate 22 having a light transmitting property made of acryl resin / polycarbonate resin formed by injection molding or the like, and a light guide plate.
  • the transmission type light scattering plate 23 attached to the end surface 2 2 d which is the reverse of the end surface 2 2 c on the side where the point light source 2 1 is arranged in 22 and the surface of the light scattering plate 23 It is composed of a reflective plate 24 attached.
  • the light scattering plate 23 and the reflection plate 24 may be held by another member such as a case body only by abutting against the end face 22 d of the light guide plate 22. It may be formed on the end face 22 d by a physical or chemical method.
  • a large number of stripe-shaped convex portions formed of a gentle slope 22a and a steep slope 22b are formed in parallel.
  • the convex portion of the shape-understand 'easy way convex part b light guide plate shape to expand is depicted schematically in 2 2
  • the light propagating along the surface of the light guide plate is totally reflected by the high light refractive index of the light guide plate even when it hits the rear surface of the light guide plate ⁇ gentle slope 22 a and does not leak to the outside. Again propagates along the plate surface, but if the angle of incidence of the light hitting the steep slope '2' 2 b.
  • the light It is emitted as leakage light 22B, and is totally reflected when the angle of incidence on the steep slope 22b is larger than the critical angle.
  • the reflected light reaches the back surface of the light guide plate 22, if the incident angle on the back surface is larger than the critical angle, it is totally reflected and propagates again in the light guide plate.
  • the incident angle on the back surface is smaller than the critical angle, the light is not reflected, and is emitted as illumination light 22 A downward from the back surface of the light guide plate 22.
  • the steep slope 2 2b becomes steeper, the average emission direction of the illumination light 22 A becomes closer to the normal direction of the plate surface of the light guide plate 22 so that the illumination efficiency is improved, but at the same time, the steep slope 2 2b Since the proportion of light at which the incident angle to the beam becomes smaller than the critical angle increases, the amount of leaked light 22B emitted from the steep slope 22b without being totally reflected also increases. The visibility becomes worse as the leakage light 22B increases, so the steep slope 22b is set to an appropriate inclination angle, for example, about 30 to 50.
  • the light emitting structure for emitting light from the back surface of the light guide plate 22 in the light guide plate 22 is not limited to the above-mentioned convex portions.
  • the light emitted from the point light source 21 is once corrected along the plate surface of the light guide plate (Rule 91). Proceed to the left side of the figure. Here, part of the light impinges on the gentle slope 22 a and the back, but most of the light is totally reflected by the gentle slope 22 a and the back and propagates while remaining in the light guide plate 22. .
  • the inclination angle of the gentle slope 2 2a is such that the light emitted from the point light source 21 and hits the gentle slope 2 2a does not leak out without being totally reflected, but the gentle slope 2 2a
  • the pitch at which the convex portions are formed is increased, and the number and area of the steep slopes 22 b are determined so as not to be reduced.
  • FIG. 2 shows a schematic configuration of a liquid crystal display device provided with the above planar light emitting body 20 as a front light.
  • This liquid crystal display device is configured by disposing a light guide plate 22 of a planar light emitting body 20 on the front side of a reflective liquid crystal display panel 30 having a reflective layer 31.
  • the planar illuminant 20 transmits external light to guide the light into the reflective liquid crystal display panel 30, and the light reflected by the reflective layer 31 reflects the reflective liquid crystal display panel.
  • the display contents formed in the 30 display area V can be visually recognized.
  • the point light source 21 when the outside is dark, the point light source 21 is turned on, so that the illumination light 22 A can be emitted from the lower surface of the light guide plate 22 toward the reflective liquid crystal display panel 30. With the illumination light 22 A, the display content formed on the reflective liquid crystal display panel 30 can be visually recognized.
  • FIG. 3 is a partial cross-sectional plan view of the above planar light-emitting body 20.
  • the three point light sources 21 are arranged substantially evenly along one end face 22 c of the light guide plate 22.
  • Each of the point light sources 21 has a light emitting characteristic having directivity such that the illuminance in the front direction is the highest as shown by the arrow in the figure, and the illuminance decreases rapidly as the point deviates from the front direction. Therefore, when lighting is performed using light traveling along the surface of the light guide plate 12 from the light source 11 as in the conventional front light shown in FIG. 5, a point light source 2 1 is used instead of the light source 1 1.
  • the scattering plate at this time may be a light scattering plate with low scattering intensity, but a structural problem arises because a sufficient distance between the light guide plate and the point light source is required. Therefore, to obtain the same effect with the point light source 21 adjacent to the light guide plate, it is necessary to use a light scattering plate having a high scattering intensity, so that light loss is large and sufficient brightness is obtained. However, there is a problem that power consumption becomes too large to obtain sufficient brightness.
  • the directivity of the point light source 21 is not so strong, it is possible to secure a certain degree of in-plane uniformity of illumination light and uniformity of leaked light even without the light scattering layer 23. it can.
  • the surface (reflection surface) of the reflection plate 24 is formed in a rough surface, or another material is selectively adhered to the surface of the reflection plate 24 to remove fine irregularities.
  • the light scattering effect may be obtained by forming.
  • fine irregularities may be formed on the end surface 22d of the light guide plate to serve as a light scattering portion.
  • the density or shape of the light emitting structure such as the above-mentioned convex portion is gradually changed along the traveling direction of light in order to make the in-plane distribution of the illumination light uniform as a planar light emitting body
  • the density and shape of the light emitting structure are changed along the traveling direction of the reflected light reflected from the reflection surface of the reflection layer such as the reflection plate 24 (that is, the right direction in FIG. 1). By doing so, the in-plane uniformity of the illumination light 22 A can be increased.
  • the planar light-emitting body of the present invention As described above, in the planar light-emitting body of the present invention, light introduced into the light guide plate from the light source travels inside the light guide plate, is reflected by the reflector plate, and becomes light that travels in a substantially predetermined direction. Since the light is emitted from the surface of the light plate, the optical path length from the light source to the emission position can be long, so the light source has directivity, the light source is a point light source, or the light source In the case where the distribution of light introduced into the light guide plate from the light is deviated, the in-plane uniformity of the emitted light can be improved. Also, when this planar light emitter is used as a front light disposed on the front side of various displays, electrical engineering devices, and electronic devices, the uneven distribution of the leakage light leaking to the front side can be reduced. The visibility can be improved.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Planar Illumination Modules (AREA)
  • Liquid Crystal (AREA)
  • Devices For Indicating Variable Information By Combining Individual Elements (AREA)

Abstract

Une source de lumière plane telle qu'une lumière avant utilise plusieurs sources de lumière ponctuelles telles que des diodes émettrices de lumière; elle empêche en même temps toute détérioration de la visibilité. Une source de lumière plane (20) qui compose une lumière avant comprend des sources de lumière ponctuelles (21) telles que des diodes lumineuses, une plaque transparente de guidage de lumière (22) telle qu'une plaque acrylique ou moulée par injection, une plaque transparente de diffusion (23) attachée à l'un des côtés (22d) de la plaque de guidage de lumière (22) opposée à l'autre côté (22c) sur lequel sont ménagées des sources ponctuelles de lumière (21), et un réflecteur ménagé à la surface de la plaque transparente de diffusion (23).
PCT/JP1999/007019 1998-12-28 1999-12-14 Source de lumiere plane, lumiere avant et afficheur a cristaux liquides WO2004083948A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US09/622,863 US6474824B1 (en) 1998-12-28 1999-12-14 Surface-emitting device, front light, and liquid crystal device

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP37358198A JP3608412B2 (ja) 1998-12-28 1998-12-28 面状発光体、フロントライト、液晶装置及び導光板
JP10/373581 1998-12-28

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Publication Number Publication Date
WO2004083948A1 true WO2004083948A1 (fr) 2004-09-30

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PCT/JP1999/007019 WO2004083948A1 (fr) 1998-12-28 1999-12-14 Source de lumiere plane, lumiere avant et afficheur a cristaux liquides

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WO (1) WO2004083948A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3968742B2 (ja) * 2000-03-30 2007-08-29 株式会社エンプラス 導光板、面光源装置及び表示装置
JP2006147451A (ja) * 2004-11-24 2006-06-08 Alps Electric Co Ltd 面発光装置及びそれを用いた表示ユニット
JP4486879B2 (ja) * 2004-12-22 2010-06-23 日本ぱちんこ部品株式会社 遊技機用発光素子式装飾装置

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62109185U (fr) * 1985-12-27 1987-07-11
JPH09113730A (ja) * 1995-10-13 1997-05-02 Omron Corp 面光源装置、当該面光源装置に用いる光学素子及び当該面光源装置を用いた画像表示装置その他の機器
JPH11184386A (ja) * 1997-12-24 1999-07-09 Seiko Instruments Inc フロントライト型照明装置およびフロントライト型照明装置付き反射型カラー表示装置

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62109185U (fr) * 1985-12-27 1987-07-11
JPH09113730A (ja) * 1995-10-13 1997-05-02 Omron Corp 面光源装置、当該面光源装置に用いる光学素子及び当該面光源装置を用いた画像表示装置その他の機器
JPH11184386A (ja) * 1997-12-24 1999-07-09 Seiko Instruments Inc フロントライト型照明装置およびフロントライト型照明装置付き反射型カラー表示装置

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Publication number Publication date
JP3608412B2 (ja) 2005-01-12
JP2000193972A (ja) 2000-07-14

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