JP4198246B2 - Surface light source element - Google Patents

Surface light source element Download PDF

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Publication number
JP4198246B2
JP4198246B2 JP32500898A JP32500898A JP4198246B2 JP 4198246 B2 JP4198246 B2 JP 4198246B2 JP 32500898 A JP32500898 A JP 32500898A JP 32500898 A JP32500898 A JP 32500898A JP 4198246 B2 JP4198246 B2 JP 4198246B2
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Japan
Prior art keywords
light source
surface
light
control plate
convex portion
Prior art date
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Expired - Fee Related
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JP32500898A
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Japanese (ja)
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JP2000148032A (en
Inventor
伊久雄 大西
洋一 橋本
陸司 渡辺
克也 藤澤
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株式会社クラレ
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Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a surface light source element using electroluminescence as a light emission source.
[0002]
[Prior art]
A transmissive display element typified by a liquid crystal panel, an advertising panel, and the like require a planar light source that emits light from the back surface thereof. One of such planar light sources is one using electroluminescence (hereinafter, electroluminescence is abbreviated as “EL”).
[0003]
[Problems to be solved by the invention]
In recent years, there has been a strong demand for thinning transmissive display elements, advertising panels, and the like. The EL light source is thin, and if an EL light source is used, a transmissive display element or the like can be thinned. However, the EL light source has a problem of low luminance.
[0004]
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a surface light source element having a feature of being thin but having high luminance using an EL as a light source.
[0005]
[Means for Solving the Problems]
The surface light source element of the present invention that solves the above-described problems includes a light source that uses electroluminescence as a light source, and a plurality of convex portions provided on a surface facing the light source, and the convex portions are in close contact with an emission surface of the light source. And an output light control plate disposed on the output surface side of the light source, and the light incident on the top of the convex portion from the light source side at an angle greater than a critical angle is output by the convex portion. It is taken out to the side. A plurality of convex portions may be provided on the surface of the outgoing light control plate opposite to the surface facing the light source.
[0006]
Of the light emitted from the light emitting layer of the EL light source, light incident at a critical angle or more with respect to the transparent substrate covering the EL light emitting layer is totally reflected and is not emitted from the transparent substrate. In the present invention, since the plurality of convex portions provided on the light incident surface of the outgoing light control plate are in close contact with the outgoing surface of the EL light source, light incident at a critical angle or more is taken out from the top of the convex portion. Can do. This can increase the brightness of the surface light source element (improve the brightness in the front direction by about 50% at the maximum).
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The principle of the present invention will be described with reference to FIGS. FIG. 2 shows a light source (EL light source) based on general electroluminescence composed of a transparent substrate 2 typified by transparent glass and the like, a transparent electrode 3 typified by ITO and the like, an electroluminescence layer 4 and a metal layer 5. It is a schematic sectional drawing of 1). FIG. 1A is a schematic cross-sectional view of a surface light source element of the present invention in which an emitted light control plate 6 is provided on the light emitting surface side of the transparent substrate 2 of the EL light source. A plurality of convex portions 9 are formed on the surface of the outgoing light control plate facing the transparent substrate 2, that is, the light incident surface 7 of the outgoing light control plate. The convex portion 9 is in close contact with and integrated with the emission surface of the transparent substrate 2 of the EL light source 1. The light generated from the light emitting layer 4 of the EL light source 1 shown in FIGS. 1A and 2 propagates through the transparent substrate 2 and reaches the light emitting surface. When the refractive index of the transparent substrate 2 is n and the emission side is air, the critical angle is θc = Sin −1 (1 / n)
(However, the refractive index of air is 1). In the light reaching the interface between the transparent substrate 2 and air, when the incident angle to the transparent substrate 2 is smaller than the critical angle, the light is refracted and emitted at the interface between the transparent substrate 2 and air (FIG. 2). Light ray L1) shown in FIG. Light incident at an angle larger than the critical angle propagates through the transparent substrate 2 again by total reflection. This reflected light is reflected again at the interface between the EL light-emitting layer 4 and the metal electrode 5. When the surface layer of the metal electrode 5 is parallel to the surface of the transparent substrate, the surface of the transparent substrate 2 and the metal electrode 5 are reflected. Multiple reflections are repeated with the surface layer of the light source and the light is not emitted from the transparent substrate 2 (light ray L2 shown in FIG. 2).
[0008]
However, according to the present invention, as shown in FIG. 1A, the top of the convex portion 9 provided on the light incident surface side of the outgoing light control plate 6 is brought into close contact with the surface of the transparent substrate 2, whereby the total reflection condition is achieved. Can also be taken into the outgoing light control plate 6. The captured light is emitted from the light exit surface 8 of the exit light control plate 6 after undergoing total reflection and refraction on the convex wall surface of the exit light control plate. The outgoing light control plate can extract light that has not been used so far, and can increase the luminance of the surface light source element. FIG.1 (b) is a schematic perspective view of an example of the surface light source element of this invention shown to Fig.1 (a).
[0009]
In the present invention, the plurality of convex portions provided on the outgoing light control plate may not have periodicity, but may have a one-dimensional or two-dimensional periodic structure. When the plurality of convex portions provided on the outgoing light control plate have periodicity, it is desirable that the ratio of the height of the convex portion to the period (pitch) of the convex portion is in the range of 1/3 to 2. If it is smaller than this range, refraction and reflection at the convex wall surface may be difficult to occur, and if it is larger than this range, EL emitted light from other than the close contact portion of the convex portion may be refracted by the convex portion. Because. The period is preferably in the range of 10 μm to 5 cm. FIG. 3 shows an example of a pattern of convex portions having periodicity provided on the light incident surface of the outgoing light control plate. FIG. 3A shows an example in the case of a two-dimensional pattern, and FIG. 3B shows an example in the case of a one-dimensional pattern. When the convex portion is a one-dimensional pattern, the angular distribution only in the direction orthogonal to the groove direction of the convex portion can be controlled. However, when the convex portion is a two-dimensional pattern, the angular distribution in both directions is controlled. Can be controlled.
[0010]
When providing a convex portion of a one-dimensional pattern on both the surface facing the light source of the outgoing light control plate and the surface opposite to the surface (outgoing surface), the convex portions of the one-dimensional pattern are in a direction perpendicular to each other. It is desirable to be provided. By providing a convex portion on the exit surface, the exit light control plate can have a function of controlling the angular distribution of the exit light from the surface light source element as well as taking out the light from the EL light source. Brightness can be increased by configuring the projections provided on the exit surface side of the exit light control plate to form a prism array.
[0011]
The cross-sectional shape of the convex pattern may be constituted by either a straight line or a curved line. In the case of a curved line, a parabola, an ellipse, or a combination of these curves is desirable. FIG. 4 shows an example of the cross-sectional shape of the convex portion on the incident surface side of the outgoing light control plate used in the present invention. The thing shown to Fig.4 (a) is comprised by the straight line. The structure shown in FIG. 4B is a curved surface, and the curved surface is elliptical. The curved surface is not limited to an ellipse, and may be a paraboloid or a curved surface formed by a combination of an ellipse and a paraboloid. In addition, by changing the shape of the convex portion provided on the incident surface side of the outgoing light control plate and the shape of the convex portion provided on the outgoing surface side, a luminance peak is obtained in an oblique direction with respect to the outgoing surface of the surface light source element. Can be directed.
[0012]
FIG. 5 shows a schematic perspective view of another specific example of the surface light source element of the present invention. In this surface light source element, a convex portion 10 is also provided on the exit surface side of the exit light control plate 6. As shown in FIG. 6, the outgoing light control plate 6 has a one-dimensional pattern of convex portions 9 on the incident side (light source side), and a one-dimensional pattern of convex portions 10 on the outgoing side. . The groove directions of these two convex portions are orthogonal to each other. The cross-sectional shape of the projection 10 on the exit side is, for example, a prism array having an apex angle of 90 °, so that the light collected by the projection 9 on the entrance side is further collected by the projection 10 provided on the exit side. Since the light can be emitted, higher luminance can be achieved.
[0013]
FIG. 7 shows a schematic perspective view of another specific example of the surface light source element of the present invention. In this surface light source element, minute projections 10 are randomly arranged on the exit surface side of the exit light control plate 6. The heights of the minute protrusions are randomly distributed in the range of 0.1 μm to 3 μm. In the case of this example, the light collected by the convex portion 9 on the incident surface side is scattered by the random convex portion 10 provided on the exit surface side, and the angular distribution of luminance is made smooth to improve the appearance. Can do. In addition, when the grating provided on the incident surface side has periodicity, the periodic pattern of the grating can be hidden by the scattering effect by the minute projections 10, so that the liquid crystal panel having periodicity with the surface light source element, etc. Moiré that occurs when combined with can be prevented.
[0014]
The said convex part of the emitted light control board used by this invention is produced by press-molding an acrylic board, for example. In addition, an ultraviolet curable resin is applied on a transparent film such as a TAC film, an acrylic film, a PET film, a PC film, and the ultraviolet curable resin is irradiated by irradiating ultraviolet rays (UV) by pressing a female mold against the film. It can also be produced by peeling the molded product from the female mold after curing. The outgoing light control plate can also be produced by injection molding using a transparent resin. The convex portion of the outgoing light control plate and the transparent substrate of the EL light source can be bonded using an ultraviolet (UV) curable adhesive.
[0015]
The material for forming the electroluminescent layer of an EL light source used as a light source in the present invention may be either organic or inorganic. Further, the present invention intends to extract light confined in the EL light source by total reflection occurring in the EL light source covered with the transparent substrate by a convex portion provided on the light incident surface side of the outgoing light control plate. Therefore, it can be used regardless of the configuration of the EL light source.
[0016]
Applications of the surface light source element of the present invention include liquid crystal backlights, advertising backlights, room lighting, signs, and the like.
[0017]
【The invention's effect】
According to the present invention, a high-brightness electroluminescent surface light source element can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating the principle of a surface light source element of the present invention.
FIG. 2 is a ray tracing diagram of a conventional surface light source element using EL.
FIG. 3 is a diagram illustrating an example of a pattern of convex portions on a light incident surface side of an outgoing light control plate.
FIG. 4 is a diagram illustrating an example of a cross-sectional shape of a convex portion of an outgoing light control plate.
FIG. 5 is a schematic perspective view of an example of the surface light source element of the present invention.
FIG. 6 is a schematic perspective view of an example of an outgoing light control plate.
FIG. 7 is a schematic perspective view of another example of the surface light source element of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electroluminescence (EL) light source 2 Transparent substrate 3 Transparent electrode 4 EL layer 5 Metal layer 6 Output light control plates 9, 10 Convex part

Claims (2)

  1. A light source that uses electroluminescence as a light source, and a plurality of convex portions are provided on a surface facing the light source, and an output disposed on the light emitting surface side of the light source so that the convex portions are in close contact with the light emitting surface of the light source. A surface light source element comprising: an emission control plate; and a light beam incident on the top of the convex portion from the light source side at an angle greater than a critical angle is extracted to the outgoing light control plate side by the convex portion.
  2. The surface light source element according to claim 1, wherein a plurality of convex portions are provided on a surface opposite to the surface facing the light source of the emitted light control plate.
JP32500898A 1998-11-16 1998-11-16 Surface light source element Expired - Fee Related JP4198246B2 (en)

Priority Applications (1)

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JP32500898A JP4198246B2 (en) 1998-11-16 1998-11-16 Surface light source element

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP32500898A JP4198246B2 (en) 1998-11-16 1998-11-16 Surface light source element

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JP2000148032A JP2000148032A (en) 2000-05-26
JP4198246B2 true JP4198246B2 (en) 2008-12-17

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011052101A1 (en) 2009-10-30 2011-05-05 富士通フロンテック株式会社 Prism plate, illumination optical system of imaging device, and mold for prism plate

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1548470B1 (en) * 2002-08-13 2014-02-12 Zeon Corporation Organic electroluminescence element comprising a lens array sheet
JP4631662B2 (en) * 2005-05-27 2011-02-23 株式会社豊田自動織機 Surface light source device, optical member, original reading device using the optical member, and surface light source device
CN102176515A (en) * 2006-01-31 2011-09-07 陶氏康宁公司 Soft lithographic molding of surface relief output couplers for organic light emitting diodes
JP5309993B2 (en) * 2006-05-31 2013-10-09 コニカミノルタ株式会社 Surface light emitter and display device
WO2008007772A1 (en) * 2006-07-13 2008-01-17 Konica Minolta Holdings, Inc. Surface light emitting body and display
JP2008021542A (en) * 2006-07-13 2008-01-31 Konica Minolta Holdings Inc Surface light emitter, display device, and lighting system
WO2008020514A1 (en) * 2006-08-17 2008-02-21 Konica Minolta Holdings, Inc. Surface light emitting apparatus
WO2008056511A1 (en) * 2006-11-08 2008-05-15 Konica Minolta Holdings, Inc. Plane emitter and display apparatus utilizing the same
JP4711264B2 (en) * 2007-03-06 2011-06-29 株式会社クラレ Surface light source element and method for manufacturing surface light source element
CN101983441B (en) * 2008-04-04 2012-11-21 皇家飞利浦电子股份有限公司 Oled device with macro extractor
WO2011115058A1 (en) 2010-03-16 2011-09-22 日東電工株式会社 Optical sheet with adhesive layer, method for producing optical sheet with adhesive layer, light source using optical sheet with adhesive layer, and image display device using optical sheet with adhesive layer

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011052101A1 (en) 2009-10-30 2011-05-05 富士通フロンテック株式会社 Prism plate, illumination optical system of imaging device, and mold for prism plate
EP3026470A1 (en) 2009-10-30 2016-06-01 Fujitsu Frontech Limited Prism plate, illumination optical system of imaging device, and forming die of prism plate

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