JP2006140114A - Planar lighting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that a former planar lighting system having a light source arranged between a light deflection control board and a light reflection member has an uneven luminance and requires much power consumption. <P>SOLUTION: The planar lighting system 10 according to the present invention comprises a plurality of planar light sources 11 extending in a first direction and aligned in a second direction crossing the first direction, a light deflection control board 12 arranged to cover the planar light sources 11, and a light reflection member 13 arranged opposite to the light deflection control board 12 to hold the planar light sources 11. The planar light source 11 includes a pair of planar light emission portions 11c and 11d facing to the light deflection control board 12 and the light reflection member 13 respectively, the light reflection member 13 includes a plurality of concave reflection surfaces 13a extending in the first direction and aligned with a predetermined space in the second direction. The alignment space of the planar light sources 11 is set to be the same as of integral multiple of that of the concave reflection surface 13a of the light reflection member 13, and the plane light emission portion 11d of the planar light source 11 facing to the light reflection member 13 is arranged across the neighboring two concave reflection surfaces 13a of the light reflection member 13. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention provides a plurality of planar light sources arranged in parallel with each other at a predetermined interval, a light deflection control plate arranged so as to cover the plurality of planar light sources, and a light deflection control across the plurality of planar light sources. The present invention relates to a flat illumination device including a light reflecting member that is disposed on the opposite side of the plate and guides light from a plurality of planar light sources to the light deflection control plate side.

  2. Description of the Related Art It is known that a flat illumination device used for a backlight light source of a transmissive liquid crystal display device is suitable for a relatively small area and that adapted for a relatively large area. Among these, as described in Patent Document 1, a light guide that fits in a relatively small area uses a plate-like light guide through which light propagates, and a light source is inserted into the light guide from the side end face of the light guide. From the light guide, and finally the light emitted from the surface of the light guide is made uniform through the light diffusion sheet and the brightness enhancement film, and the light quantity distribution is made uniform and the direction of the emitted light is controlled. On the other hand, as described in Patent Document 2 and Patent Document 3, a light diffusion sheet and a brightness enhancement film are arranged on the opposite side of the light reflecting member with the light source interposed therebetween, as described in Patent Document 2 and Patent Document 3. The light emitted from the light source is all guided to the light diffusion sheet and the brightness enhancement film side by the light reflecting member, and the light quantity distribution of the outgoing light passing through the light diffusion sheet and the brightness enhancement film is made uniform and its direction is controlled. Yes.

  The light diffusing sheet described above scatters highly directional light in a nearly completely diffusing state, contributing to uniform light quantity distribution, and the brightness enhancement film, on the contrary, gives specific directivity to scattered light. Contribute. By appropriately using these two types of sheets together, the light quantity distribution of the emitted light is made uniform and the directivity is adjusted.

Japanese Patent Laid-Open No. 9-292531 Japanese Patent No. 3267725 JP 2001-215497 A

  In the conventional flat illumination device described in Patent Document 1, since the light source is arranged on the side of the light guide, the thickness of the flat illumination device itself can be set thin. Because it is limited around the light guide, it is difficult to use it as a backlight source for large liquid crystal display devices with a large display area, and it is possible to uniformly emit high-intensity light from the entire surface of the light guide plate. It can be difficult. In addition, when the light guide is enlarged with an increase in display area, the light guide itself cannot be increased in thickness in order to maintain mechanical strength, and the weight increases and the interior increases. There was a drawback that the loss of propagating light also increased.

  In the case of the conventional flat illumination devices described in Patent Document 2 and Patent Document 3, since there is no restriction as in the case of using a light guide with respect to the arrangement of the light source, such a problem can be solved. If the optical path length from the illumination surface of the flat illumination device to the exit surface of the illumination light is set long, it becomes a factor that hinders the compactness of the flat illumination device. For this reason, if the thickness of the flat illumination device itself is to be reduced, the optical path length from the light source to the exit surface of the illumination light of the flat illumination device cannot be taken sufficiently. As a result, unevenness in the luminance distribution and light quantity distribution is likely to occur, and in order to avoid this, it is necessary to use a plurality of light diffusion sheets having the disadvantage of increasing light loss, or to arrange the light sources more densely than necessary. In this case, there are problems in terms of cost and power consumption. Further, the conventional straight tube type cold cathode tube used as a light source has a uniform radiation characteristic of light from the center thereof, so that the utilization efficiency of the emitted light is not so good. In addition, in the case of using a light reflecting member in which a concave reflecting surface having a constant curvature surrounding the light source is continuously formed according to the arrangement interval of the light sources, the light reflected at the boundary portion of the adjacent concave reflecting surface becomes a strong bright line. As a result, it reaches a light diffusion sheet and a brightness enhancement film, and causes a large brightness unevenness.

  An object of the present invention is to provide a compact flat illumination device that is less likely to cause unevenness in luminance distribution and light amount distribution and that can be adapted to large-area illumination.

  A planar illumination device according to the present invention includes a plurality of planar light sources that extend in a first direction and are arranged at predetermined intervals along a second direction that intersects the first direction, and the plurality of planar light sources. A transparent light deflection control plate disposed so as to cover the plurality of planar light sources, and disposed on the opposite side of the light deflection control plate across the plurality of planar light sources, and controls the light deflection from the plurality of planar light sources. Each of the planar light sources has a pair of flat planar light emitting portions facing the light deflection control plate and the light reflecting member, respectively. The light reflecting member has a plurality of concave reflecting surfaces extending in the first direction and arranged at predetermined intervals along the second direction, and the arrangement intervals of the plurality of planar light sources are It is set to be equal to or an integral multiple of the arrangement interval of the concave reflecting surfaces of the light reflecting member, and the light reflecting member It is characterized in that the plane emitting part of the planar light source is positioned in two adjacent astride the concave reflecting surface of the light reflecting member.

  In the present invention, the light emitted from one planar light emitting portion of the planar light source facing the light deflection control plate proceeds as it is to the light deflection control plate side, and the light emitted from the other planar light emitting portion facing the light reflecting member. Advances toward the light reflecting member, is totally reflected by the concave reflecting surface, and is guided to the light deflection control plate side. The light finally emitted from the planar light source is emitted from the light deflection control plate in a state where the emission direction and the dispersion state are controlled. Further, most of the light reflected at the boundary portion between the two adjacent concave reflection surfaces is blocked by the planar light source arranged so as to cover the boundary portion, and does not reach the light deflection control plate side.

  In the flat illumination device according to the present invention, the planar light source may be a cold cathode tube using hard glass.

  Each concave reflecting surface has a symmetrical shape with an intermediate position along the second direction as a center, while including the center of each planar light source and in a first direction perpendicular to the light deflection control plate The along plane may be a boundary between two adjacent concave reflecting surfaces.

  The concave reflecting surface can be formed by a continuous curved surface or a plurality of planes extending in the first direction.

  A width dimension along the second direction of each planar light source is set to be equal to or less than a width dimension of each concave reflecting surface along the second direction of the light reflecting member, and a pair of planar light emission of each planar light source It is preferable that the interval between the portions is set smaller than the width dimension along the second direction of the planar light source. In this case, it is effective to set the width dimension along the second direction of each planar light source to a range of 2 to 10 times the interval between the pair of planar light emitting portions.

  The light deflection control plate may have a light deflection member for deflecting light passing through the light deflection control plate in a predetermined direction.

  A cold cathode tube can be employed as the planar light source, and the electrode can be formed elongated along the second direction. In this case, the electrode may have a large number of uneven portions or a net shape.

  According to the planar illumination device of the present invention, the planar light source has a pair of flat planar light emitting portions facing the light deflection control plate and the light reflecting member, the light reflecting member extends in the first direction and Having a plurality of concave reflection surfaces arranged at predetermined intervals along the direction of 2, the arrangement interval of the plurality of planar light sources is set to be the same as the arrangement interval of the concave reflection surfaces of the light reflecting member, or an integer multiple, Since the planar light emitting part of the planar light source facing the light reflecting member is positioned so as to straddle two adjacent concave reflecting surfaces of the light reflecting member, direct light from the planar light source and the concave reflecting surface The light reflected and passed between the adjacent planar light sources is guided to the light deflection control plate, while the planar light source blocks the reflected light that is difficult to control at the boundary between the two adjacent concave reflecting surfaces. The brightness and illuminance distribution of the illumination light emitted from the light deflection control plate can be made more uniform than the conventional one. Can or Rukoto. In addition, since the light source has a flat planar light emitting portion facing the light deflection control plate and the light reflecting member, most of the light emitted from the light source can be efficiently emitted from the light deflection control plate.

  Each concave reflecting surface has a symmetrical shape with an intermediate position along the second direction as a center, while including the center of each planar light source and in a first direction perpendicular to the light deflection control plate If the plane along the line is the boundary between two adjacent concave reflecting surfaces, the direct light from the planar light source and the light reflected by the concave reflecting surface and passed between the adjacent planar light sources It can be guided to the light deflection control plate in the state of being alternately overlapped along the second direction, the distance between the light reflecting member and the planar light source, the inclination angle and the curvature of each concave reflecting surface of the light reflecting member, etc. Can be designed in the same manner, and manufacturing and assembly thereof can be facilitated.

  A width dimension along the second direction of each planar light source is set to be equal to or less than a width dimension of each concave reflecting surface along the second direction of the light reflecting member, and a pair of planar light emission of each planar light source When the interval between the portions is set to be smaller than the width dimension along the second direction of the planar light source, the emitted light from the planar light emitting portion of the planar light source facing the light reflecting member is directed to two adjacent concave reflecting surfaces. Can be reflected to the light deflection control plate side, and the ratio of the light emitted from the planar light source to the light deflection control plate and the light reflecting member side can be set more, and the light emitted from the light source can be set. The utilization efficiency can be improved as compared with the conventional one. Such an effect becomes remarkable particularly when the width dimension along the second direction of each planar light source is set in a range of 2 to 10 times the interval between the pair of planar light emitting portions. The same lighting effect can be achieved with lower power consumption.

  When the light deflection control plate has a light deflection member for deflecting light passing through the light deflection control plate in a predetermined direction, it becomes possible to adjust the directivity of the illumination light emitted from the light deflection control plate, Higher luminance illumination light can be emitted in a desired direction.

  If a cold cathode tube is adopted as a planar light source and the electrode has a large number of irregularities or is net-like, the current concentration at the electrode is relaxed, thereby dispersing the heat generation of the electrode, The deterioration is prevented and stable discharge is possible over a long period of time.

  Embodiments of the flat illumination device according to the present invention will be described in detail with reference to FIGS. 1 to 6, but the present invention is not limited to these embodiments, and further combinations thereof are described in the claims. Any change or modification encompassed by the disclosed concept of the present invention is possible, and can of course be applied to any other technique belonging to the spirit of the present invention.

  The appearance of the flat illumination device in this embodiment is shown in FIG. 1 in an exploded state, the cross-sectional structure of the main part is shown in FIG. 2, and the appearance of the planar light source in this embodiment is shown in FIG. That is, the flat illumination device 10 according to the present embodiment extends in a first direction perpendicular to the paper surface of FIG. 2 and crosses the first direction (the left-right direction in FIG. 2). ), A plurality of planar light sources 11 arranged at predetermined intervals, an optically transparent light deflection control plate 12 arranged so as to cover the plurality of planar light sources 11, and a plurality of planar light sources 11 A light reflecting member 13 disposed on the opposite side of the light deflection control plate 12 to guide light from the plurality of planar light sources 11 to the light deflection control plate 12 side, the planar light source 11, the light deflection control plate 12, A housing 14 for accommodating and holding the light reflecting member 13 is provided.

The light reflecting member 13 in the present embodiment is formed by pressing a metal such as aluminum into a corrugated shape, but when formed of a resin, a white powder such as barium titanate is used to improve the light shielding property and the light reflectance. A resin material in which the body (pigment) is kneaded, for example, a liquid crystal polymer made of an aromatic polyester, a modified polyamide, polybutylene terephthalate, nylon 46, or the like can be used. The light reflecting member 13 has a plurality of concave reflecting surfaces 13a extending in the first direction and arranged at predetermined intervals along the second direction. Each concave reflecting surface 13a has a symmetrical shape with an intermediate position along the second direction as a center, and includes a center of each planar light source 11 and is perpendicular to the light deflection control plate 12. A plane along the direction (indicated by a two-dot chain line in FIG. 2) forms a boundary between two adjacent concave reflecting surfaces 13a. Individual concave reflecting surface 13a is a cross-sectional shape along the second direction forms a 1/2 small predetermined radius of curvature of the arcuate than these arrangement pitch P _13, but a parabolic or elliptical other such It is possible to form a quadratic curve or a higher-order curve, or to form a state in which a number of planes approximating this are connected. The concave reflecting surface 13a may be a mirror surface, or may be a smooth surface or a fine rough surface such as a satin surface. In any case, a metal foil or a resin sheet is attached to the surface or machined. Thus, the concave reflecting surface 13a can be finished.

The planar light source 11 in this embodiment is formed of a flat hard glass cold-cathode tube, and projecting dimet wires 11b connected to the electrodes 11a from both ends in the longitudinal direction. The pair of electrodes 11a formed from a metal plate has a flat shape elongated in the second direction corresponding to the cross-sectional contour shape of the flat cold cathode tube, and thereby a part of the electrode 11a. In addition to preventing the current from concentrating on the electrode 11a, the heat dissipation of the electrode 11a itself is improved to prevent the deterioration of the durability and thermal deformation, while allowing stable discharge over a long period of time. In this embodiment, the tip surface of one electrode 11a is formed as a convex surface and the tip surface of the other electrode 11a is formed as a concave surface. However, the shape of the electrode 11a itself and its tip surface is a cold cathode. It goes without saying that it can be appropriately changed according to the characteristics of the tube. Each planar light source 11 has a pair of upper and lower flat planar light emitting portions 11c and 11d facing the light deflection control plate 12 and the light reflecting member 13, respectively. Width W along the second direction of each of the surface light source 11 is set to the array pitch P ₁₃ following each concave reflecting surface 13a in the second direction of the light reflecting member 13. Moreover, the space | interval (thickness) H of a pair of planar light emission part 11c, 11d of each planar light source 11 is smaller than the width dimension W along the 2nd direction of the planar light source 11, and the planar illuminating device 10 whole. Are appropriately set according to the size, required luminance characteristics, electrical characteristics, mechanical strength of the planar light source 11 itself, optical characteristics, electrical characteristics, and the like. Usually, the width dimension W along the second direction of the planar light source 11 is set in a range of 2 to 10 times the interval H between the pair of planar light emitting portions 11c and 11d. Thus, since the planar light emitting portions 11c and 11d are wide with respect to the thickness of the planar light source 11, light with high luminance can be obtained even if the number of planar light sources 11 incorporated in the planar illumination device 10 is small. Can be emitted from the light deflection control plate 12. The arrangement pitch P ₁₁ of the surface light source 11 is set to the same interval as the arrangement pitch P ₁₃ of the concave reflecting surface 13a of the light reflecting member 13, the planar light emitting portion 11d of the light reflecting member 13 facing the planar light source 11 is light The reflecting member 13 is positioned so as to straddle two adjacent concave reflecting surfaces 13a.

  In this way, by arranging the planar light source 11 so as to cover the boundary portion between the two adjacent concave reflecting surfaces 13a, a strong bright line reflected at the boundary portion is blocked by the planar light source 11, and thus light deflection control is performed. There is an advantage that the luminance distribution of the light emitted from the plate 12 can be easily uniformed.

  The light deflection control plate 12 is made of acrylic resin (PMMA), polycarbonate (PC), polyethylene terephthalate (PET) or the like, and has fine irregularities for deflecting light passing therethrough in a predetermined direction. Thus, the illuminance distribution and luminance distribution of illumination light emitted from the surface of the light deflection control plate 12 are adjusted to desired characteristics (generally uniform). As this light deflection control plate 12, a so-called prism sheet or a so-called light diffusing plate can be used, or one obtained by superimposing a plurality of sheets as required, such as JP-A-2003-35824. It is also possible to employ a light deflection element described in 1) formed as fine irregularities.

  When the illumination area of the flat illumination device 10 is relatively small, the casing 14 can be formed by aluminum die casting or sheet metal processing. However, when the illumination area of the flat illumination device 10 is relatively large, a light reflecting member. It can be said that it is preferable from the viewpoint of weight reduction to adopt the one in which the same resin casing 14 as 13 is injection-molded.

  Therefore, the light emitted from the flat light emitting portion 11 c of the planar light source 11 on the side facing the light deflection control plate 12 proceeds to the back surface 12 a of the light deflection control plate 12. Further, the light emitted from the planar light emitting portion 11d of the planar light source 11 on the side facing the light reflecting member 13 mainly travels to the two concave reflecting surfaces 13a located immediately below, and is reflected here and mutually reflected. It finally reaches the back surface 12 a of the light deflection control plate 12 from between the adjacent planar light sources 11. In this way, the light directly reaching the back surface 12a of the light deflection control plate 12 from the planar light source 11 and reflected from the planar light source 11 by the light reflecting member 13, and passes between the adjacent planar light sources 11. Thus, the illuminance distribution and the luminance distribution of the illumination light emitted from the front surface 12b of the light deflection control plate 12 are uniform over the entire area of the light deflection control plate 12 by the light reaching the back surface 12a of the light deflection control plate 12. As described above, the distance between the planar light source 11 and the light deflection control plate 12 and the light reflecting member 13, the contour shape of the concave reflecting surface 13 a of the light reflecting member 13, the surface roughness of the light reflecting member 13, and the arrangement interval thereof. It is necessary to set appropriately.

  Thus, after preparing an appropriate number of planar light sources 11 having a length corresponding to the width dimension of the optical deflection control plate 12 along the first direction, the planar light sources 11 and the optical deflection control plate 12 and The surface 12b of the light deflection control plate 12 is set by appropriately setting the distance between the light reflecting member 13, the contour shape of the concave reflecting surface 13a of the light reflecting member 13, the surface roughness of the light reflecting member 13, and the arrangement interval thereof. The illuminance distribution and luminance distribution of the illumination light emitted from can be made uniform.

In the embodiment described above, although the array pitch P ₁₁ of the concave reflecting surface 13a of the arrangement pitch P ₁₃ and the planar light source 11 of the light reflecting member 13 was set to be the same, the array pitch of the concave reflecting surface 13a of the light reflecting member 13 it is also possible to set the P ₁₃ to an integral multiple of the arrangement pitch P ₁₁ of the surface light source 11.

FIG. 4 shows a cross-sectional structure of another embodiment of the flat illumination device 10 according to the present invention. Elements having the same functions as those of the previous embodiment are designated by the same reference numerals, and redundant description is omitted. It shall be. That is, in the present embodiment, the arrangement pitch P ₁₃ of the concave reflection surfaces 13 a of the light reflecting member 13 is set to be twice the arrangement pitch P ₁₁ of the planar light sources 11, and the individual planar light sources 11 facing the light reflecting member 13. This is the same as the previous embodiment in that the planar light emitting part 11d is positioned so as to straddle two adjacent concave reflecting surfaces 13a of the light reflecting member 13. In this case, since the boundary portion between the two concave reflection surfaces 13a exists in the middle of the adjacent planar light sources 11, there is a concern that the reflected light of this portion becomes a relatively strong emission line. However, since the incident angle of the light from the planar light source 11 is shallow with respect to the boundary portion between the two concave reflecting surfaces 13a, the reflected light is rather rather than the light deflection control plate 12 side. Since it propagates to the side (in the left-right direction in FIG. 4), it reaches the light deflection control plate 12 in a state where the intensity is considerably weakened. In other words, the bright lines that are difficult to control do not reach the light deflection control plate 12, and the same effect as in the previous embodiment can be obtained.

  In addition, it is also possible to employ | adopt the electrode 11a as shown in FIG.5 and FIG.6 as the electrode 11a of the flat cold cathode tube used in embodiment mentioned above. That is, the electrode 11a shown in FIG. 5 has a large number of concave and convex portions. For example, the electrode 11a is made porous by etching a large surface, made of continuously foamed metal, or metal that has been subjected to mechanical perforation. The electrode 11a block can be employed. Further, the electrode 11a shown in FIG. 6 is formed by three-dimensionally forming a metal net, and each has an elongated contour shape corresponding to the cross-sectional contour shape of the cold cathode tube, and the effective surface area of the electrode 11a is reduced. It spreads to prevent current concentration and dissipates the heat generated by the electrode 11a itself, which is intended for stable discharge over a long period of time, and has a structure in which the jimet wire 11b protrudes rearward from the rear end.

It is a three-dimensional projection figure showing the external appearance of one Embodiment of the planar illuminating device by this invention in a decomposition | disassembly state. It is an expanded sectional view of the planar illuminating device shown in FIG. It is the stereographic projection figure showing the external appearance of the planar light source integrated in the planar illuminating device shown in FIG. It is an extraction enlarged view showing the other shape of the electrode part of the planar light source shown in FIG. It is an extraction enlarged view showing another shape of the electrode part of the planar light source shown in FIG. It is sectional drawing showing the structure of the principal part in other embodiment of the planar illuminating device by this invention.

Explanation of symbols

10 planar illumination device 11 planar light source 11a electrode 11b Zimmet lines 11c, 11d planar light emitting portion 12 light deflection control plate 12a back surface 12b surface 13 the light reflecting member 13a concave, reflective surface 14 arranged in the casing P ₁₁ planar light source pitch P ₁₃ concave reflector Arrangement pitch of surface W Width of planar light source H Distance between pair of planar light emitting parts

Claims (6)

A plurality of planar light sources that extend in the first direction and are arranged at predetermined intervals along a second direction that intersects with the first direction, and a transparent that is arranged to cover the plurality of planar light sources A light deflection control plate, and a light reflection member disposed on the opposite side of the light deflection control plate across the plurality of planar light sources, and guiding light from the plurality of planar light sources to the light deflection control plate side A flat lighting device comprising:
Each of the planar light sources has a pair of flat planar light emitting portions facing the light deflection control plate and the light reflecting member,
The light reflecting member has a plurality of concave reflecting surfaces extending in the first direction and arranged at predetermined intervals along the second direction,
The arrangement interval of the plurality of planar light sources is set to be the same as or an integer multiple of the arrangement interval of the concave reflection surfaces of the light reflecting member, and the planar light emitting unit of the planar light source facing the light reflecting member is A flat illumination device characterized by being positioned so as to straddle two adjacent concave reflecting surfaces of a light reflecting member.   Each of the concave reflecting surfaces has a symmetrical shape with an intermediate position along the second direction as a center, and includes a center of each of the planar light sources and a first perpendicular to the light deflection control plate. 2. The flat illumination device according to claim 1, wherein a plane along the direction of the line forms a boundary between two adjacent concave reflection surfaces.   The width dimension along the second direction of the individual planar light source is set to be equal to or less than the width dimension of the individual concave reflecting surface along the second direction of the light reflecting member, and the individual planar light source 3. The flat illumination device according to claim 1, wherein an interval between the pair of planar light emitting units is set to be smaller than a width dimension along the second direction of the planar light source. .   The width dimension along the 2nd direction of the said each planar light source is set to the range of 2 to 10 times the space | interval of the pair of planar light emission part, The Claim 3 characterized by the above-mentioned. Planar lighting device.   5. The planar illumination according to claim 1, wherein the light deflection control plate has a light deflection member for deflecting light passing through the light deflection control plate in a predetermined direction. apparatus.   The planar illumination device according to any one of claims 1 to 5, wherein the planar light source is a cold cathode tube, and an electrode thereof has a large number of uneven portions or has a net shape.

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