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
• • 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
  • G02B6/0036—2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• • 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
  • G02B6/0053—Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• • 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
• • 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
  • G02B6/0045—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 by shaping at least a portion of the light guide
  • G02B6/0046—Tapered light guide, e.g. wedge-shaped light guide

Definitions

• the present invention relates to a liquid crystal display device used for a notebook personal computer, a liquid crystal television, etc., a signage device such as a guide signboard or a large signboard at a station or a public facility, and various information signs and traffic signs on an expressway or a general road. More specifically, the present invention relates to a surface light source element constituting a display device such as a traffic sign device, and more specifically, has a high luminance and a uniform luminance distribution in a light emitting surface without performing a uniform processing such as a speckle pattern. Is obtained with respect to the surface light source element. Background art
• This liquid crystal display device basically includes a backlight section and a liquid crystal display element section.
• the backlight part there are a direct type in which a light source is provided directly below the liquid crystal display element and an edge light type in which a light source is provided facing the side end surface of the light guide. It has been heavily used.
• the edge light method is a backlight in which a light source is arranged on a side surface of a plate-shaped light guide to emit light on the entire surface of the light guide, and is called a so-called surface light source element.
• a plate-shaped transparent material such as an acryl resin plate is used as a light guide, and light from a light source disposed facing the side end face is transmitted from the side end face (light incident surface) to the light guide.
• a light emission function such as a light scattering portion formed on the front surface or the back surface of the light guide, the light is emitted from the entire light emission surface in a planar manner. Things.
• an internal lighting system is used to enhance nighttime visibility and legibility.
• Two lighting methods, external lighting are used.
• characters, figures, photographs, etc. are formed on a translucent plastic plate such as a methacrylic plate by cutting or printing to form a display panel, and a light source is placed inside the display panel.
• a straight tube or ring-shaped fluorescent lamp is generally used as a light source.
• a light source is arranged above, below, and on the front side of the display panel on which the display contents are formed, and this light source illuminates the entire surface of the display panel.
• Straight tube fluorescent lamps are commonly used.
• Japanese Patent Application Laid-Open No. 1-245252 discloses a light emitting function in which a light diffusing substance is densely applied or adhered to the back surface of the light guide opposite to the light emitting surface as the distance from the light incident surface increases.
• Provided surface light source elements have been proposed.
• Japanese Patent Application Laid-Open No. H11-106406 discloses that a light guide is formed by laminating a plurality of transparent plates on the surface of which fine spots made of a light scattering substance are formed in various patterns. Proposed.
• a white pigment such as titanium oxide / sulfuric acid barrier is used as a light scattering substance, light loss such as light absorption when light impinging on the light scattering substance is scattered. Therefore, the brightness distribution can be made uniform, but there is a problem that the brightness of the emitted light is reduced.
• Japanese Patent Application Laid-Open Nos. 1-244049 and 1-2525333 disclose a light reflection pattern corresponding to the reciprocal of the emission light distribution on the light emission surface of the light guide.
• a surface light source element in which an emitted light adjusting member and a light diffusion plate are arranged.
• the light reflected by the emission light adjusting member and the light diffusion plate cannot be reused, light loss occurs, and the luminance of the emitted light in a desired direction is reduced. there were.
• Hei 2-846618 disclose a light-emitting surface of a light guide and at least one of its back surface with a matte surface or a large number of lens units.
• a surface light source element which is formed and has a prism sheet mounted on a light emitting surface has been proposed.
• a surface light source element can obtain a very high luminance, it is still unsatisfactory in terms of uniformity of the luminance distribution on the light emitting surface, and is only a small surface light source element of about several inches. could not be used.
• a matte surface or a number of lens units are formed on the emission surface, and a rough surface portion and a smooth portion are formed on the back surface so that the ratio of the rough surface portion increases as the distance from the light source increases, and a prism sheet is formed on the light emission surface.
• a matte surface or a number of lens units are formed on the emission surface, and a rough surface portion and a smooth portion are formed on the back surface so that the ratio of the rough surface portion increases as the distance from the light source increases, and a prism sheet is formed on the light emission surface.
• Such a surface light source element can achieve a uniform luminance distribution of emitted light and reduce light loss
• a display device such as a liquid crystal display device or a display device
• the liquid crystal display device or The pattern formed by the rough surface portion and the smooth portion formed on the back surface of the light guide through the display plate was observed, which had a problem that the observation of the image was hindered. Disclosure of the invention
• an object of the present invention is to provide a surface light source element having high luminance and excellent uniformity of luminance distribution on a light emitting surface without performing a uniform processing of a speckle pattern or the like.
• the present inventors have made intensive studies on the structure of the light exit surface or the back surface of the light guide, and as a result, By providing a rough surface consisting of fine irregularities with a constant average inclination angle or a fine irregular surface consisting of a large number of lens rows, it is possible to have high brightness and to perform uniform processing such as a speckle pattern.
• the present inventors have found that a surface light source element having excellent uniformity of the luminance distribution of the emitted light within the light emitting surface can be obtained, and have arrived at the present invention.
• a light guide in the surface light source element of the present invention, includes a light source, at least one side end face facing the light source as a light incident surface, and one surface substantially orthogonal to the light incident surface as a light emitting surface. And a light deflection sheet provided on the light exit surface side of the light guide, and the light exit surface of the light guide and at least one of the back surfaces thereof have an average inclination angle of 0.5. ⁇ 7.5. It is characterized by having a microstructure of:
• the surface light source element of the present invention comprises a light source, and a light guide having at least one side end surface facing the light source as a light incident surface and one surface substantially orthogonal to the light incident surface as a light emitting surface.
• a lens sheet provided on the light exit surface side of the light guide and having a large number of lens rows formed in parallel on at least one surface, and the light exit surface of the light guide and the back surface thereof
• At least one surface is composed of a rough surface composed of a large number of substantially spherical fine convex bodies, and has an average inclination angle of 0.5 to 7.5 °. is there.
• a light source at least one side end surface facing the light source is a light incident surface, and one surface substantially orthogonal to the light incident surface is a light emitting surface.
• a light guide, and a lens sheet provided on the light exit surface side of the light guide and having a large number of lens rows formed in parallel on at least one of the surfaces, and the light of the light guide is provided.
• the outgoing surface and at least one of the back surface extend in a direction parallel to the light incident surface, and have an average inclination angle of 0.5 to 7.5. It is characterized by being constituted by a large number of lens rows each having an inclined surface.
• a liquid crystal display device, a sign device, and a traffic sign device of the present invention are characterized by using the above-described surface light source element as a backlight.
• a large number of minute spherical convex bodies having an average inclination angle of 0.5 to 7.5 ° are provided on at least one of the light exit surface and the back surface of the light guide.
• the light emitted from the light exit surface of the light guide is formed by forming a large number of lens arrays consisting of inclined surfaces with an average inclination angle of 0.5 to 7.5 ° in a direction parallel to the light incident surface.
• the light emission rate of the light can be reduced, thereby increasing the amount of light propagating in the light guide toward the front end, and reducing the luminance in the light emission surface without performing a uniform processing such as a speckle pattern. High uniformity can be obtained.
• FIG. 1 is a perspective view showing a surface light source element of the present invention.
• FIG. 2 is a schematic diagram showing an optical path of light on a light exit surface of the light guide of the present invention.
• FIG. 3 is a coordinate system in which the spherical shape of the convex body of the present invention is simplified to a circle.
• FIG. 4 is a partial sectional view showing a prism surface of the light guide of the present invention.
• FIG. 5 is a partial sectional view showing a lenticular lens surface of the light guide of the present invention.
• FIG. 6 is a side view showing an example of the light guide of the surface light source element of the present invention.
• FIG. 7 is a side view showing an example of the light guide of the surface light source element of the present invention.
• FIG. 8 is a partial perspective view showing the liquid crystal display device of the present invention.
• FIG. 9 is a graph showing a model of the distribution of light emitted from the light guide.
• FIG. 10 is a chart of the surface roughness of the rough surface according to the first embodiment of the present invention. This is a chart of the fraction coefficient and the second derivative.
• FIG. 11 is a chart of the surface roughness of the rough surface of Comparative Example 1 of the present invention, and a chart of its first derivative and second derivative.
• FIG. 12 is a partial cross-sectional view showing a prism surface of a light guide according to a comparative example.
• FIG. 13 is a partial cross-sectional view showing a lenticular lens surface of a light guide according to a comparative example.
• the surface light source element of the present invention has a light source having an elongated light source 2, at least one light incident surface 11 facing the light source 2, and a light emitting surface 12 substantially orthogonal to the light source.
• the light guide 1 includes a light guide 1 and a light deflection sheet 3 including a lens sheet such as a prism sheet mounted on a light exit surface 12 of the light guide 1.
• the light incident on the light guide 1 from the light source 2 is such that light having a distribution exceeding the critical angle is totally reflected on the light exit surface 12 and the back surface 13 of the light guide 1 repeatedly. It propagates through the light guide 1.
• FIG. 2 schematically shows the refraction and reflection of light in the light guide 1 having irregularities on the surface.
• the light once incident on the concave and convex portions and reflected changes the incident angle when subsequently entering the concave and convex portions, so that light is emitted out of the light guide 1.
• the present inventors have found that the relationship between the light emission intensity (I) at a certain point and the light emission intensity (1.) at the end of the light incident surface is as follows: the emission ratio ( ⁇ ), the light incident surface It was found that the following formula (1) was experimentally satisfied by the distance (L ') from the end and the thickness (t) of the light guide 1.
• the uniformity of the brightness distribution of the emitted light within the light emitting surface 12 depends on the emission rate ( ⁇ ) You can see it.
• the emission rate ( ⁇ ) of the light guide 1 having a thickness of t (mm) is measured at a distance of 20 mm from the end of the light entrance surface of the light guide 1 and the distance ( ⁇ ) from the end of the light entrance surface ( From the ratio (L '/ t) of the ratio (L') to the thickness (t) of the light guide 1 (L '/ t) and the logarithm of the luminance, the gradient (K (mm "')) is obtained, and the following (2 ).
• the uniformity of the luminance distribution in the surface light source element is evaluated and examined by using the degree of variation (R%) expressed by the following equation (3) as a measure of the uniformity of the luminance distribution.
• the degree of variation (R%) is 20% in the range from the point 5 mm away from the edge of the light incident surface to the opposite edge at the substantially central part of the light guide 1 (the central part in the longitudinal direction of the light source 2).
• the luminance is measured at mm intervals, and the maximum value of the measured luminance (I max ), the minimum value of the measured luminance (I m , n), and the average value of the measured luminance (lav) are obtained, and the following formula (3) is used. .
• the emission rate ( ⁇ ) and the degree of variation (R%) are determined by the length of the light guide 1 ( L) and the thickness (t) are found to have a specific relationship depending on As the rate ( ⁇ ) increases, the degree of variation (R%) increases accordingly. If the emission rate ( ⁇ ) is constant, the ratio (L) of the light guide 1 to the thickness (t) ( As LZ t) increases, the degree of variation (R%) also increases. That is, in the light guide 1 having a certain size, the uniformity (variability) of the luminance distribution in the light emitting surface 12 of the light guide 1 depends on the emission rate ( ⁇ ) from the light guide 1. It was found that uniformity of the luminance distribution could be achieved by controlling the emission rate ( ⁇ ).
• the present inventors have proposed a case where the surface (light emitting surface 12, back surface 13) of the light guide 1 is constituted by a rough surface of fine irregularities made up of a large number of substantially spherical convexes.
• the fine irregular shape is considered to be a slope having approximately one slope.
• the average inclination angle ( ⁇ a) specified in IS 04287/1 — 1987 can be used as the gradient.
• the average inclination angle ( ⁇ a) increases, the light emitted from the light guide 1 becomes closer to the normal direction of the light emitting surface 1 2 (the direction of the thickness t of the light guide 1). .
• the emission rate ( ⁇ ) from the light guide 1 also increases accordingly. For this reason, the uniformity of the luminance distribution in the light emitting surface 12 of the surface light source element can be increased by lowering the emission rate ( ⁇ ) from the light guide 1, and the average inclination angle ( ⁇ It has been found that uniformity can be achieved by reducing a).
• the light emitting surface 12 of the light guide 1 and at least one of the back surfaces 13 thereof are provided with an average inclination angle (ea) force of 0.5 to 7.It is composed of a rough surface of 5 ° or a number of lens rows.
• the emission rate ( ⁇ ) from the light guide 1 can be sufficiently reduced, and the luminance distribution in the light emission surface 12 of the surface light source element can be made uniform. is there. This is because if the average inclination angle ( ⁇ &) of the rough surface is less than 0.5 °, the total amount of light emitted from the light exit surface 12 of the light guide 1 decreases, and sufficient luminance cannot be obtained.
• the average inclination angle (0a) of the rough surface exceeds 7.5 °, the emission rate ( ⁇ ) of the light guide 1 increases, and the uniformity of luminance is impaired as a surface light source element.
• the average inclination angle (0a) of the rough surface exceeds 7.5 °, the emission rate ( ⁇ ) of the light guide 1 increases, and the uniformity of luminance is impaired as a surface light source element.
• the average inclination angle (0a) of the rough surface exceeds 7.5 °, the emission rate ( ⁇ ) of the light guide 1 increases, and the uniformity of luminance is impaired as a surface light source element.
• the average inclination angle (0a) of the rough surface exceeds 7.5 °, the emission rate ( ⁇ ) of the light guide 1 increases, and the uniformity of luminance is impaired as a surface light source element.
• ( ⁇ a) is 1-6. And more preferably in the range of 2 to 5 °.
• the average inclination angle (S a) of the rough surface with fine irregularities was determined by measuring the surface roughness of the rough surface formed on the light guide surface with a stylus type surface roughness meter at a driving speed of 0.03 mmZ seconds. It can be obtained by measuring and correcting the slope by subtracting the average line from the chart obtained by this measurement, and calculating by the following equations (4) to (5).
• "" indicates the distance scanned by the stylus
• X indicates the measurement position
• f (x) indicates the variation of the stylus.
• the light emission rate ( ⁇ ) from the light emission surface 12 of the light guide 1 is set to 1 to 4.5. % Is preferable. This is because if the light emission rate ( ⁇ ) from the light emission surface of the light guide is less than 1%, the emission angle of the light emitted from the light emission surface (The angle with respect to the normal line of the light emitting surface 12) becomes large, and it tends to be difficult to sufficiently direct the emitted light in the normal direction even if a deforming member such as a prism sheet is used.
• the emission ratio ( ⁇ ) exceeds 4.5%, the uniformity of the luminance distribution tends to be impaired as a surface light source element of a liquid crystal display device or the like.
• the emission ratio ( ⁇ ) is in the range of 1 to 4%, more preferably in the range of 1.2 to 3.5%.
• the peak of the maximum light intensity of the light emitted from the light exit surface of the light guide 1 is 6 5
• the angle between the direction of the peak indicating the maximum light intensity of the emitted light and the direction at which the light intensity is 50% of the maximum light intensity is 20 degrees or less. It is preferable to emit light with such directivity. This is because the peak indicating the maximum light intensity of the emitted light is less than 65 degrees with respect to the normal to the light emitting surface, or the direction of the peak indicating the maximum light intensity of the emitted light and 50% of the maximum light intensity. If the angle formed by the direction exceeds 20 degrees, the emission rate ( ⁇ ) from the light guide 1 increases, and it tends to be impossible to achieve uniform brightness distribution on the light emission surface. It is.
• the surface light source element requires as high a luminance as possible, it is preferable that the light emitted from the surface light source element be concentrated in the observation direction.
• the angle between the direction of the peak indicating the maximum light intensity of the light emitted from the light guide 1 and the direction indicating the intensity of 10% of the maximum light intensity is 50 degrees or less. This is because if this angle exceeds 50 degrees, the amount of light emitted in directions other than the observation direction increases even when the optical bending sheet is used, and there is a tendency that sufficiently high luminance cannot be obtained in the observation direction. That's why.
• the radius of curvature of the convexes is uniform. It is preferable that the average period (P), the minute average radius of curvature (R), and the average deviation of the minute average radius of curvature of the fine convex body constituting the surface of the light guide 1
• (S) satisfy a specific relationship. That is, the ratio (RZ P) between the minute average radius of curvature (R) and the average period (P) of the convex body is in the range of 3 to 10, and the ratio of the minute average radius of curvature to the minute average radius of curvature (R) is It is preferable that the ratio (SZR) of the average deviation (S) of the distribution be within a range of 0.85 or less. This is because when the ratio (RZP) between the small average radius of curvature of the convex body and the average period is less than 3, the average inclination angle ( ⁇ a) of the substantially spherical surface irregularities due to the convex body increases.
• RZP is preferably in the range of 5-7.
• the ratio (SZR) of the average deviation of the distribution of the minute average radius of curvature to the minute average radius of curvature exceeds 0.85, the distribution of the convex bodies constituting the surface of the light guide 1 becomes non-uniform. This is because the uniformity of the luminance distribution in the light emitting surface of the light guide 1 tends to decrease, and the SZR is preferably in the range of 0.8 or less, more preferably 0.7 or less. Range.
• the average period ( ⁇ ) of the convex body is determined by measuring the surface of the light guide 1 on a straight line of a given length (for example, l OOO ix m) in any direction in a surface roughness meter. This is the average value of the period calculated from the number of peaks of the convex body of, and calculated from the number of peaks of the convex body.
• the minute average radius of curvature (R) can be determined as follows from a chart obtained by measuring the surface of the light guide 1 composed of the convex body with a surface roughness meter. First, the spherical shape of the convex body is simplified to an arc. In the coordinate system shown in Fig. 3, when the radius of the circle is r, it is expressed by the following equation (6).
• equation (8) As commonly used in the design of optical lenses, if the central part of the spherical surface of the convex body is used, r> x, and the approximate expression of equation (7) is expressed as the following equation (8).
• the sphere (arc) can be replaced by a quadratic curve
• the second derivative is equal to the reciprocal of the radius. Accordingly, the second-order differential coefficient of the chart curve measured by the surface roughness meter is obtained, and the average value of the reciprocal thereof is obtained, whereby the minute average radius of curvature (R) of the present invention is obtained.
• the small average radius of curvature (R) is expressed by the following equation (10). Since the average deviation (S) of the small average radius of curvature (R) indicates a deviation from the average value, it is expressed by the following equation (11).
• the minute average radius of curvature (R) and the average deviation (S) thereof use values obtained by detecting a minute region with a value of 5 or less, and the ratio of the minute average radius of curvature to the minute average radius of curvature (R) is used.
• the ratio (SZR) of the average deviation (S) of the distribution is expressed by the following equation (12).
• n In order to increase the brightness of the R surface light source element, it is desirable that the light emitted from the surface light source element be concentrated in the viewing direction, and the light emitted from the light guide 1 should be concentrated in one direction. Is desirable.
• a rough surface constituting at least one of the light emitting surface 12 and the back surface 13 of the light guide is provided in order to emit such outgoing light concentrated in one direction from the light guide 1. Is preferably a rough surface in which the area where the minute average inclination angle ( ⁇ a) is 20 ° or more is 2% or less.
• the small average inclination angle ( ⁇ ⁇ &) is small.
• the area over 20 ° is less than 1%.
• the emission rate ( ⁇ ) from the light guide 1 when the emission rate ( ⁇ ) from the light guide 1 is reduced as in the present invention, the ratio of light propagating and returning while reflecting in the light guide 1 increases, and Since the amount of light emitted from the device tends to decrease, it is desirable to further increase the luminance as the surface light source element by concentrating the emission direction of the emitted light in one direction.
• the haze value is preferably in the range of 20 to 40%. This is a light guide
• a surface light source element with a small degree of variation in luminance (R%) and excellent uniformity can be obtained.
• ( ⁇ ) is relatively small, the ratio of light that travels back and forth while reflecting in the light guide 1 increases, and the amount of light emitted from the light guide 1 tends to decrease. This is because it is desirable to increase the brightness of the image. Therefore, by performing a roughening treatment so that the haze value of the light guide 1 is in the range of 20 to 40%, the luminance as the surface light source element can be further increased. If the haze value of the light guide 1 is less than 20%, the unevenness forming the rough surface becomes small, and the luminance as the surface light source element cannot be sufficiently increased. If it exceeds, the unevenness of the rough surface becomes intense, causing unevenness in the emitted light and decreasing the uniformity of the luminance distribution.
• the haze value is preferably in the range of 30 to 40%.
• a processing method for uniformly forming a large number of specific, substantially spherical, fine convex bodies on the light guide 1 but, for example, rough processing is performed by chemical etching using hydrofluoric acid or the like.
• Metal or glass molds with surfaces formed, glass A method in which a rough surface is formed by blasting fine particles such as beads, a mold in which a rough surface is formed by using blast and chemical etching together, or the like, and the rough surface is transferred by heat press, injection molding, or the like; Examples thereof include a method of applying or attaching a transparent substance to the light guide 1 in a concavo-convex shape by a printing method or the like, and a method of directly processing the light guide 1 by a blast method / etching method.
• the surface of a glass plate is blasted by spraying fine particles such as glass beads, and then the processed surface is chemically etched with hydrofluoric acid or the like to form a rough surface. It is preferable to form the light guide 1 by transferring a rough surface or by injection molding a transparent resin into such a mold.
• the number of lens rows formed on the surface of the light guide 1 has an average inclination angle (0a) of 0.5 to 7.5.
• the lens array is not particularly limited as long as it is a lens array composed of inclined surfaces such as an array of lenticular lenses having an arc-shaped cross section, a prism array having a saw-tooth cross-section, and a concavo-convex array having a continuous cross-section having a waveform. No. Among them, a prism array (FIG. 4) and a lenticular single lens array (FIG. 5) having symmetrical cross sections are particularly preferable.
• Such a lens array is formed so that the lens array extends in a direction parallel to the light incident surface 11 of the light guide 1, and preferably, each lens array is formed continuously in parallel.
• the pitch of the lens rows is appropriately selected depending on the application, but is usually preferably in the range of 20 ⁇ m to 5 mm.
• a processing method for forming a large number of lens rows composed of inclined surfaces having a specific average inclination angle ( ⁇ &) on the surface of the light guide for example, chemical etching, byte cutting, laser processing, etc.
• An active energy linear curing resin is placed on the transparent substrate. Coated and shaped and cured by irradiation with active energy rays to form a lens Examples include a method of transferring a pattern, a method of directly processing the light guide 1 by etching, bit cutting, laser processing, or the like.
• the size of the light guide 1 used in the surface light source element of the present invention is not particularly limited, but the length (the length of the light guide 1 ( It is preferable to use the light guide 1 having a ratio (LZ t) of L) to the thickness (t) of 200 or less.
• LZt exceeds 200, uniformity of the luminance distribution on the light emitting surface cannot be sufficiently achieved even if the rough surface of the light guide 1 or the average inclination angle ( ⁇ &) of the lens array is reduced.
• LZt is more preferably 150 or less. In particular, when it is used as a liquid crystal display device, it is preferably at most 100, more preferably at most 80.
• the light guide 1 a transparent plate made of glass, synthetic resin, or the like can be used.
• synthetic resin for example, various highly transparent synthetic resins such as an acrylic resin, a polycarbonate resin and a butyl chloride resin can be used.
• the light guide 1 can be manufactured by molding into a plate by a molding method.
• methacrylic resin is excellent in light transmittance, heat resistance, mechanical properties, and moldability, and is suitable as a light guide material.
• the methacrylic resin a resin having a methyl methacrylate unit content of 80% by weight or more is preferable.
• glass beads, inorganic fine particles such as titanium oxide, and resin fine particles such as a styrene resin, an acrylic resin, and a silicone resin can be dispersed as a light diffusing material.
• a light source 2 such as a flashlight is disposed adjacent to one end (incident end face 11) of the light guide 1 as described above, and faces the light emitting face 12.
• a reflection layer 4 is formed by a reflection film or the like.
• the light source 2 and the light incident surface 11 of the light guide 1 are configured to be covered with a case-film 5 coated with a reflective agent on the inside.
• the light guide 1 may have a plate shape, a wedge shape (thickness t gradually decreases in the L ′ direction) as shown in FIG. 6, or a shape (L ′ direction) as shown in FIG. (Thickness t gradually decreases toward the center at both ends).
• the emission direction of the light emitted from the light guide 1 is usually light having a directivity of 60 to 80 ° from the normal to the emission surface 12.
• a light bending sheet 3 is placed on the light guide 1.
• the variable optical angle sheet 3 used include a diffusion sheet and a lens sheet having a lens surface in which a large number of lens units are formed in parallel on at least one surface.
• the lens shape formed on the lens sheet various shapes are used depending on the purpose, and examples thereof include a prism shape, a lenticular lens shape, and a wavy shape.
• the pitch of the lens unit of the lens sheet is 30 ⁇ !
• the prism apex angle is appropriately selected according to the emission angle of the light emitted from the light guide. It is preferable to be in the range of 50 to 120 °. Also, the direction of the lens sheet is appropriately selected according to the exit angle of the light emitted from the light guide, and the lens may be placed so that the lens surface is on the light guide side, or may be placed in the opposite direction. May be. In general, when the light guide 1 having a rough surface having a specific average inclination angle ( ⁇ &) as described above or a surface constituted by a large number of lens rows is used, the apex angle is 50 to 75.
• ⁇ & specific average inclination angle
• variable optical angle sheets 3 can be used as needed.
• the two lens sheet forces can be stacked and used so that the respective lens rows are at an angle or parallel to each other.
• the lens sheets can be placed so that each lens surface is in the upper or lower direction, and the lens surfaces of both lens sheets are in opposite directions. Can also.
• the first lens sheet adjacent to the light guide 1 is mounted such that the lens surface is on the light guide side and the lens array 31 is parallel to the light source. (See Fig. 1), and then place the second lens sheet so that the lens surface is on the opposite side of the light guide, and the lens row is orthogonal to the lens row of the first lens sheet.
• the first prism sheet should have an apex angle of 50 to 75 °
• the second prism sheet should have an apex angle of 80 to 75 °. 1 0 0. It is preferable to use those.
• the lens sheet is preferably manufactured using a material having a high visible light transmittance and a relatively high refractive index.
• a material having a high visible light transmittance and a relatively high refractive index for example, acrylic resin, polycarbonate resin, vinyl chloride resin, active energy ray curing Mold resin and the like.
• an active energy ray-curable resin is preferred from the viewpoints of scratch resistance, handleability, productivity and the like of the lens sheet.
• additives such as an antioxidant, an ultraviolet absorber, an anti-yellowing agent, a bluing agent, a pigment, and a diffusing agent can be added to the lens sheet as needed.
• a usual molding method such as extrusion molding, injection molding or the like can be used.
• a polyester resin, an acrylic resin, or a polycarbonate resin may be used.
• the lens portion is formed by an active energy ray-curable resin on a transparent substrate such as a transparent film or sheet made of a transparent resin such as lunar chloride resin, polymethacrylimide resin, or polyolefin resin.
• an active energy linear curing resin liquid is injected into a lens mold having a predetermined lens pattern, and a transparent base material is superposed.
• an active energy ray such as an ultraviolet ray or an electron beam is irradiated through the transparent base material, and the active energy ray-curable resin liquid is polymerized and cured, and is separated from the lens mold to obtain a lens sheet.
• the lens sheet as described above, as well as a diffusion sheet, a color filter, a polarizing film, and the like, are used to optically change, converge, and diffuse light, Various optical elements that change characteristics can be used.
• a general straight tube fluorescent lamp can be used as the light source 2, but if it is difficult to replace the light source 2, it is necessary to separately use a line light composed of a plurality of optical fibers. Light can be transmitted from the installed light source.
• a liquid crystal display device 7 is mounted on the light emitting surface side of the surface light source device configured as described above, so that a liquid crystal display device used for a notebook computer, a liquid crystal television, or the like is provided.
• a liquid crystal display device used for a notebook computer, a liquid crystal television, or the like can be used as In such a liquid crystal display device, a very high uniformity of the luminance distribution is required, and the degree of variation (R%) is 30% or less, preferably 25% or less, and more preferably 20% or less.
• a sign board formed by cutting, printing, or the like on a translucent plastic board such as a methacryl board is placed on a translucent plastic board, so that it can be used in stations and public facilities.
• the degree of variation (R%) is set to 250% or less, preferably 200% or less.
• methacrylic By mounting a road sign or a traffic sign etc. on a plastic plate such as a plate by cutting or printing, it is used as a traffic sign device for various guide signs and traffic signs on expressways and general roads. can do.
• the variation (R%) is set to 450% or less, preferably 300% or less.
• the luminance is measured at 20 mm intervals from the light incident surface end of the light guide, and the ratio (L '/ t) of the distance (L') from the light incident surface end to the thickness (t) of the light guide 1 is measured.
• the gradient (K (mm " 1 )) was obtained from the graph of the logarithm of luminance and the logarithm, and was obtained by the above equation (2).
• the luminance is measured at intervals of 2 Omm within the range from the point 5 mm away from the edge of the light incident surface to the opposite end in the approximate center of the light guide parallel to the light incident surface, and the maximum value of the measured luminance (I TM ax ), the minimum value of the measured luminance (I min ), and the average value of the measured luminance (I av ) were determined, and were determined by the above equation (3).
• the cold-cathode tube was connected to a DC power supply via an inverter (TDK CX A—M10L), and was lit by applying 12 V DC.
• the light guide was placed on the measuring table, and the center was adjusted so that it rotated about the axis of rotation parallel to the axis of the cold-cathode tube.
• the position of the meter (NT-1 ° manufactured by Minolta) was adjusted.
• the rotation axis was rotated from + 85 ° to -85 ° at 1 ° intervals, and the luminance of the emitted light was measured with a luminance meter.
• the cold-cathode tube was connected to a DC power supply via an inverter (available from D-01 Corporation—1 ⁇ 110 L), and was lit by applying 12 V DC.
• the surface light source element was mounted on a measurement table, and the center was adjusted so that it rotated on a rotation axis parallel to the cold cathode tube axis.
• the brightness of the emitted light was measured using a luminance meter with the rotation axis set to 0 °. The measurement was performed by excluding 5 mm near the cold cathode tube of the light guide, dividing the other part into squares of 20 mm square, measuring the brightness at the center of each square, and averaging the measured values. To obtain the normal luminance.
• the surface roughness of the rough surface is measured in the same manner as in the case of the average tilt angle ( ⁇ &), and the resulting chatter is divided into n pieces at 1 mm intervals.
• ( ⁇ ⁇ a) was calculated by the above equation (13). From these calculation results, the ratio of the number of microscopic regions having a microscopic average inclination angle ( ⁇ 3) of 20 ° or more to the number of all microscopic regions was determined.
• the first derivative (K i) at 5 ⁇ intervals on a straight line having a length of 1000 in the arbitrary direction of the light guide was determined.
• the obtained first derivative (K i) was sequentially connected, and was calculated from the number (m) crossing 0 using the following equation (16).
• the radius of curvature (r,) at five intervals on a straight line having a length of 1 000 in an arbitrary direction of the light guide and the small average radius of curvature (R) were obtained from the above equation (11).
• the surface of the glass plate is made of glass beads with a particle size of 125 to 149 / urn (FGB-120 manufactured by Fuji Seisakusho), and the distance from the glass plate to the spray nozzle is set to 10 cm.
• the blast treatment was performed at a spray pressure of 4 Kg_cm 2 .
• chemical etching of the blast surface is performed by performing a fluorine treatment, and a thickness of 4 mm, 16.5 mm X 210 mm is obtained by using an electrode obtained by taking a replica by an electrode.
• the rough surface was transferred to one surface of the transparent acrylic resin plate by thermal transfer to obtain a light guide.
• the rough surface of the obtained light guide had a structure in which fine convex bodies having a substantially spherical shape were uniformly distributed.
• the ratio of the region where the average inclination angle (S a) and the minute average inclination angle ( ⁇ &) of the light guide were 20 ° or more was measured, and the results are shown in the table.
• FIG. 10 shows a chart of the surface roughness of the obtained light guide, which was measured by using a stylus type surface roughness meter.
• the first derivative and second derivative were obtained, and are shown in FIG. 10 respectively.
• Table 1 shows the structural parameters of the light guide surface.
• the angle distribution of the emitted light from the light guide was measured, and the angle (peak angle) of the peak direction indicating the maximum light intensity with respect to the normal line, the peak direction indicating the maximum light intensity, and the maximum Angle between direction indicating 50% of light intensity (angle difference of 50% intensity from peak), angle between peak direction indicating maximum light intensity and direction indicating 10% intensity of maximum light intensity (Angle difference of 10% intensity from peak force>) was obtained and is shown in Table 1.
• One end face of 210 mm and two ends of 1 65 mm of the obtained light guide A PET film on which silver was deposited was adhered to the surface by adhesion processing, and a PET film on which silver was deposited was taped on the back surface opposite to the roughened light emitting surface to form a reflective surface.
• a straight tube fluorescent lamp (KC230T4E, 4 mm ⁇ X2 30 mm, manufactured by Matsushita Electric Industrial Co., Ltd.) is installed on one end face of the remaining 210 mm of the light guide, and the light of the light guide is A prism sheet with a number of parallel prism rows with a vertical angle of 63 ° and a pitch of 50 ⁇ made of acrylic UV curable resin with a refractive index of 1.53 on a PET film on the exit surface.
• the device was mounted so as to face the light emission surface side to form a surface light source element. Table 1 shows the normal luminance of the obtained surface light source element.
• a light guide was produced in the same procedure using a transparent acrylic resin plate having a thickness of 3 mm and a thickness of 90 mm ⁇ 300 mm.
• a silver-evaporated PET film was attached to the two end faces of 30 Omm of the obtained light guide by adhesive processing, and the silver-evaporated PET film was taped to the back surface opposite to the roughened light emission surface.
• a reflection surface was formed.
• a straight tube-type fluorescent lamp (KC130T4E, 4 mm ⁇ x 130 mm, manufactured by Matsushita Electric Industrial Co., Ltd.) was installed on one end of the light guide at 90 mm. Using this surface light source element, the emission ratio and the degree of variation (R%) of the light guide were determined and are shown in Table 1.
• the surface of the mirror-finished stainless steel plate was made 10 cm from the stainless steel plate to the spray nozzle using glass beads (FGB-120 manufactured by Fuji Seisakusho) with a particle size of 125 to 149 wm.
• the blast treatment was performed at a spray pressure of 4 K / cm 2 .
• a rough surface was transferred by heat transfer to one surface of a transparent acryl resin plate having a thickness of 3 mm and a size of 165 mm ⁇ 210 mm to form a light guide.
• the angle between the direction indicating the intensity of 50% of the maximum light intensity (the angle difference of 50% intensity from the peak) and the direction between the peak direction indicating the maximum light intensity and the direction indicating the intensity of 10% of the maximum light intensity was determined and shown in Table 1.
• the obtained light guide was used as a surface light source element in the same manner as in Example 1.
• Table 1 shows the normal luminance of the obtained surface light source element.
• the emission ratio and the degree of variation (R%) of the light guide were determined and are shown in Table 1.
• Example 2 Using the stainless steel plate mold used in Example 2, the rough surface was transferred to one surface of a transparent acrylic resin plate having a thickness of 4 mm and a size of 16.5 mm x 210 mm by a mature transfer to obtain a light guide.
• the obtained light guide had the same structure, physical properties, and characteristics as the light guide of Example 2.
• the obtained light guide was used as a surface light source element in the same manner as in Example 1.
• Table 1 shows the normal luminance of the obtained surface light source element.
• the emission ratio and the degree of variation (R%) of the light guide were determined and are shown in Table 1.
• a transparent acrylic resin plate was used in the same manner as in Example 1, except that one end of 210 mm was 3 mm thick and the other end was 1 mm thick. A light guide was obtained.
• the obtained light guide had the same structure, physical properties, and characteristics as in Example 1.
• a surface light source element was prepared in the same manner as in Example 1 except that a straight tube-type fluorescent lamp was installed on the end face side of the obtained light guide having a thickness of 3 mm.
• Table 1 shows the normal luminosity of the obtained surface light source element, and the emission ratio ( ⁇ ) and the degree of variation (R%) of the light guide.
• a light guide was obtained in the same manner as in Example 2 except that 74 to 88 urn (FGB-200 manufactured by Fuji Seisakusho) was used as glass beads for blasting.
• the average inclination angle (S a) and the small average inclination angle ( ⁇ ⁇ ) of the obtained light guide were measured at a ratio of 20 ° or more, and the results are shown in Table 1.
• the surface roughness chart of the rough surface of the optical body measured using a stylus-type surface roughness meter is shown in Fig. 11.
• the first derivative and second derivative were obtained, and Fig. 11
• the structural parameters of the surface of the light guide are shown in Table 1. Furthermore, the angle distribution of the emitted light from the light guide was measured using this light guide, and the peak direction showing the maximum light intensity was obtained.
• the angle (peak angle) with respect to the normal line indicates the maximum light intensity
• the angle between the direction of the peak and the direction showing 10% of the maximum light intensity indicates the maximum light intensity
• the obtained light guide was used as a surface light source element in the same manner as in Example 1.
• Table 1 shows the normal luminance of the obtained surface light source element.
• the emission ratio and the degree of variation (R%) of the light guide were determined and are shown in Table 1.
• Comparative Example 2 Using the stainless steel plate mold used in Comparative Example 1, the rough surface was transferred by thermal transfer to one surface of a transparent acryl resin plate having a thickness of 4 mm and a size of 165 mm ⁇ 21 O mm to obtain a light guide.
• the obtained light guide had the same structure, physical properties, and characteristics as in Example 2.
• the obtained light guide was used as a surface light source element in the same manner as in Example 1.
• Table 1 shows the normal luminance of the obtained surface light source element.
• the emission ratio and the degree of variation (R%) of the light guide were determined and are shown in Table 1.
• Table 1 shows the results of measuring the ratio of the area where the average inclination angle ( ⁇ &) and the minute average inclination angle (A 6> a) of the obtained light guide were 20 ° or more.
• the rough surface of the obtained light guide was measured using a stylus type surface roughness meter, and Table 1 shows one structural parameter of the light guide surface.
• the angle distribution of the emitted light from the light guide is measured, and the angle (peak angle) of the peak direction indicating the maximum light intensity to the normal line, the peak direction indicating the maximum light intensity, and the The angle between the direction indicating the intensity of 50% of the maximum light intensity (the angle difference of 50% intensity from the peak) and the angle between the peak direction indicating the maximum light intensity and the direction indicating the intensity of 10% of the maximum light intensity ( The angle difference of 10% intensity from the peak) was calculated and shown in Table 1.
• the normal luminance of the obtained surface light source element was obtained and is shown in Table 1.
• Table 1 shows the emission ratio and the degree of variation (R%) of the light guide obtained by using the surface light source element configured in the same manner as in Example 1.
• a diamond plate is used as a square plate, and a number of prism rows with a vertical angle of 172 ° and a pitch of 50 ⁇ m corresponding to the shape shown in Fig. 4 are arranged in parallel.
• the prism surface was transferred by thermal transfer to one surface of a 4 mm ⁇ 210 mm ⁇ 165 mm transparent acryl resin plate to form a light guide.
• the average tilt angle ( ⁇ &) of the obtained light guide was 4.2 °.
• a silver-evaporated PET film is adhered to two end surfaces of 165 mm and one end surface of 210 mm of the obtained light guide by adhesive processing, and the back surface opposite to the light emission surface which is a prism surface
• a PET film with silver deposited on it was taped to form a reflective surface.
• a cold-cathode tube (KC 230 T4 E, 4 mm 0 X 23 O mm) made of silver-evaporated PET film was wound around the other end face of the light guide and installed as a light source lamp.
• the light source was mounted so as to face the light emitting surface side of the light emitting device.
• Table 2 shows the normal luminance of the obtained surface light source element.
• a light guide was produced in the same procedure using a 3 mm x 90 mm x 300 mm transparent acryl resin plate.
• a surface light source element was prepared in the same manner as described above, except that a PET film on which silver was vapor-deposited was adhered to two end faces of 30 Omm of the obtained light guide, and the obtained surface was obtained.
• Table 2 shows the emission ratio and degree of variation (R%) of the light guide of the light source element.
• the lenticular lens surface was transferred by heat transfer to one surface of a transparent acrylic resin plate of mm x 210 mm x 165 mm to form a light guide.
• the average inclination angle ( ⁇ &) of the obtained light guide was 4.3 °.
• the obtained light guide was a surface light source element in the same manner as in Example 5. did.
• Table 2 shows the normal luminance of the obtained surface light source element.
• a surface light source element was produced in the same manner as in Example 5, and the emission ratio and the degree of variation (R%) of the light guide of the obtained surface light source element were determined and are shown in Table 2.
• a mold with a prism pattern in which many prism rows with apical angle of 164 ° and pitch of 50 corresponding to the shape as shown in Fig. 12 were formed in parallel was used.
• the prism surface was transferred to one surface of a transparent acryl resin plate of 4 mm ⁇ 210 mm ⁇ 165 mm by thermal transfer to form a light guide.
• the average inclination angle ( ⁇ &) of the obtained light guide was 8.2 °.
• the obtained light guide was used as a surface light source element in the same manner as in Example 5.
• Table 2 shows the normal luminance of the obtained surface light source element.
• a surface light source element was manufactured in the same manner as in Example 5, and the emission ratio and the degree of variation (R%) of the light guide of the obtained surface light source element were determined and are shown in Table 2.
• Example 2 In the same manner as in Example 1, a rough surface was transferred by thermal transfer to one surface of a transparent acryl resin plate having a thickness of 10 mm and a thickness of 600 mm ⁇ 250 mm to form a light guide.
• the average inclination angle ( ⁇ &) and the small average inclination angle ( ⁇ ⁇ 8) of the obtained light guide were measured in the region where the average inclination angle was 20 ° or more.
• the structure of the rough surface of the obtained light guide and the emission light characteristics were the same as those in Example 1.
• a silver-evaporated PET film was attached to the 600 mm ⁇ end face and the 1250 mm two end faces of the obtained light guide by adhesive processing, and silver was applied to the back surface facing the roughened light emission surface.
• the reflective surface was formed by tape-taping the deposited PET film.
• a 30W fluorescent lamp (FSL 30T 6W manufactured by Matsushita Electric Industrial Co., Ltd.) was installed on one end face of the remaining 600 mm of the light guide, and a PET film with a refractive index of 1.53 was placed on the light exit surface of the light guide.
• a surface light source is mounted on a prism sheet made of an acrylic ultraviolet curable resin and formed with a large number of parallel prism rows with a vertical angle of 63 ° and a pitch of 50 rn, with the prism surface facing the light emitting surface side of the light guide.
• the element was used.
• Table 3 shows the normal luminance of the obtained surface light source element.
• a light guide was manufactured in the same procedure using a transparent acryl resin plate having a thickness of 10 mm and a thickness of 600 mm ⁇ 250 mm.
• a silver-evaporated PET film is attached to the two end faces of 1 250 mm of the obtained light guide by adhesive processing, and the silver-evaporated PET film is taped to the back surface opposite to the roughened light emission surface.
• a 30 W fluorescent lamp FSL 30 T 6 W, manufactured by Matsushita Electric Industrial Co., Ltd.
• This surface light source element Table 3 shows the emission ratio and the degree of variation (R%) of the light guide using the above.
• a rough surface was transferred by thermal transfer to one surface of a transparent acryl resin plate having a thickness of 10 mm and a thickness of 600 mm X 125 Omm to obtain a light guide.
• the average inclination angle ( ⁇ & ) and the small average inclination angle (ASa) of the obtained light guide were measured at a rate of 20 ° or more, and the results are shown in Table 3.
• the structure of the rough surface and the emission light characteristics of the obtained light guide were the same as those in Comparative Example 1.
• the obtained light guide was used as a surface light source element in the same manner as in Example 7.
• Table 3 shows the normal luminance of the obtained surface light source element.
• the emission ratio and the degree of variation (R%) of the light guide were determined and are shown in Table 3.
• the prism surface was transferred to one surface of a transparent acrylic resin plate of 10 mm ⁇ 600 mm ⁇ 250 mm by thermal transfer to form a light guide.
• the average inclination angle (Sa) of the obtained light guide was 4.2 °.
• a silver-evaporated PET film was adhered to the two end faces of 1250 mm and one end face of 600 mm of the obtained light guide by adhesive processing, and silver was applied to the back surface opposite to the light emitting surface that was the prism surface.
• the reflective surface was formed by tape-taping the deposited PET film.
• a 30W fluorescent lamp (Matsushita Electric FSL 30T6) is wound around a PET film on which silver is deposited on the other end face of the light guide, and the light guide is installed as a light source lamp.
• a prism sheet is formed on the PET film by forming a large number of parallel prism rows with a vertical angle of 63 ° and a pitch of 50 ⁇ using an acrylic UV curable resin with a refractive index of 1.53.
• the prism surface emits light from the light guide.
• a surface light source element was mounted so as to face the surface side. Normal luminosity of the obtained surface light source element Table 4 shows the measured values.
• a light guide was produced in the same procedure.
• a surface light source device was prepared in the same manner as described above, except that silver-deposited PET films were adhered to the two end surfaces of 1250 mm of the obtained light guide, and then adhered.
• Table 4 shows the emission ratio and the degree of variation (R%) of the light guide of the device.
• Example 6 the lenticular lens surface was transferred to one surface of a transparent acrylic resin plate of 10 mm ⁇ 600 mm ⁇ 250 mm by thermal transfer to obtain a light guide.
• the average inclination angle (Sa) of the obtained light guide was 4.3 °.
• the obtained light guide was used as a surface light source element in the same manner as in Example 8.
• Table 4 shows the normal luminance of the obtained surface light source element.
• a surface light source element was produced in the same manner as in Example 8, and the emission ratio and the degree of dispersion (R%) of the light guide of the obtained surface light source element were determined and are shown in Table 4.
• the prism surface was transferred by thermal transfer to one surface of a transparent acrylic resin plate of 10 mm ⁇ 600 mm ⁇ 1250 mm to form a light guide.
• the average inclination angle (0a) of the obtained light guide was 8.2 °.
• the obtained light guide was used as a surface light source element in the same manner as in Example 8.
• Table 4 shows the normal luminance of the obtained surface light source element.
• a surface light source element was manufactured in the same manner as in Example 8, and the emission ratio and the degree of variation (R%) of the light guide of the obtained surface light source element were determined and are shown in Table 4.
• the prism surface was transferred by thermal transfer to one surface of a transparent acrylic resin plate of 10 mm x 600 mm x l 250 mm to form a light guide. did.
• the average inclination angle (0a) of the obtained light guide was 8.3 °.
• the obtained light guide was used as a surface light source element in the same manner as in Example 8.
• Table 4 shows the normal luminance of the obtained surface light source element. Further, a surface light source element was manufactured in the same manner as in Example 8, and the emission ratio and the degree of variation (R%) of the light guide of the obtained surface light source element were determined and are shown in Table 4.
• a translucent acryl plate on which a photograph was printed or a translucent acryl plate on which a traffic sign was printed was arranged on the surface light source elements of Examples 7 to 9 and Comparative Examples 6 to 8 to form a large signboard and a traffic sign. Signs and signs using the surface light source elements of Examples 7 to 9 of the present invention were very bright and uniform. On the other hand, when the surface light source elements of Comparative Examples 6 to 8 were used, a relatively bright screen was observed in the vicinity of the light source, but the brightness decreased remarkably as the distance from the light source increased, and the brightness was extremely reduced near the end. It was dark. Industrial applicability
• the light emitting surface of the light guide and at least one of the back surface facing the light guide have an average inclination angle (O 3) composed of a large number of substantially spherical fine protrusions of 0.5 to 0.5, for example. 7. Form a rough surface of 5 °, or form a number of lens rows composed of inclined surfaces with an average tilt angle ( ⁇ a) of 0.5 to 7.5 °, and obtain an average tilt angle (S a ) Has a high brightness by forming a microstructure of 0.5 to 7.5 °, and a surface light source that shows a uniform brightness distribution in the light emitting surface without performing uniform processing such as a speckle pattern.
• Table Example 1 Example 2 ms 4 rows of thighs 1 row of rows 2 1: Image 3
• ⁇ a 20 ° iiLh 0 0.5 0.5 0 3 3 4 Ratio (%)
• ⁇ ⁇ ⁇ a 20 ° or more 0 3 ratio (%)

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• 1997
  • 1997-01-31 CN CN97192605A patent/CN1078335C/zh not_active Expired - Lifetime
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