JP4652987B2 - Surface lighting device - Google Patents

Description

  The present invention has a light guide plate that diffuses light emitted from a light source and emits illumination light from a light exit surface, and is a planar illumination device that illuminates indoors or outdoors, or a liquid crystal display panel, an advertising panel, an advertising tower, The present invention relates to a planar lighting device used as a backlight for a signboard or the like.

  In recent years, the size of devices has been increasing in liquid crystal display panels and indoor and outdoor planar illumination devices. Along with this, the light guide plates used in these lighting devices are also required to be enlarged. In that case, for example, a method of producing one large light guide plate having a periodic structure is taken.

  However, in this method, the larger the size of the light guide plate, the more difficult the production and the higher the cost. Therefore, a method is adopted in which a plurality of unit light guide plates are connected. This makes it easier to manufacture and lowers the cost than using a large light guide plate.

  However, when a plurality of unit light guide plates are connected to support a large apparatus, a small amount of illumination light leaks from the connection portion of each unit light guide plate when the light source emits light. May occur. The bright line generated in the gap between the light guide plate coupling parts is caused by a strong light beam being emitted from a narrow area. However, there is a possibility that the bright line part is clearly visible and may be noticeable. For this reason, unevenness occurs in the illumination light, making it difficult to display an accurate image or achieving uniform illumination.

  An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a planar illumination device capable of suppressing uneven emission lines generated when connecting a plurality of unit light guide plates and emitting light without unevenness. It is to provide.

  In order to achieve the above object, the present invention comprises a plurality of unit light guide plates each having a linear light source and an individual light exit surface, the unit light guide plate being disposed adjacent to another unit light guide plate, A light exit surface that is flush with the individual light exit surface of the unit light guide plate, diffuses light emitted from the linear light source, and exits from the light exit surface; and the light of the light guide plate A planar illuminating device having a diffusing material for diffusing illumination light emitted from an emission surface, wherein the unit light guide plate has an uneven surface on a surface facing an adjacent unit light guide plate. A planar lighting device is provided.

  Further, in the unit light guide plate, it is preferable that the uneven shape of the surface facing the adjacent unit light guide plate is a shape obtained by inverting the uneven shape of the end surface of the adjacent unit light guide plate, and further, the unit light emitting surface It is preferable to have a plurality of parallel grooves in which the linear light sources are arranged on the opposite surface.

  Alternatively, the unit light guide plate has a concavo-convex shape of a surface facing an adjacent unit light guide plate having irregularities in a cross section in a direction parallel to the light exit surface, or of a surface facing the adjacent unit light guide plate. It is preferable that the concavo-convex shape has irregularities in a cross section in a direction perpendicular to the light exit surface.

According to the present invention as described above, uneven illumination can be reduced by dispersing the bright lines generated in the connecting portion when a plurality of unit light guide plates are connected. Thereby, even when a planar illumination device such as a large illumination or a liquid crystal monitor is used, illumination with no unevenness is possible.
Furthermore, since the connecting portion of the unit light guide plate is not a flat surface but has an uneven shape, it is possible to prevent misalignment when connecting the unit light guide plates and improve the alignment accuracy of the connecting portion. To do.

The planar lighting device of the present invention will be described below.
FIG. 1 is a schematic perspective view showing an embodiment of the planar lighting device according to the present invention and showing an appearance viewed from the light exit surface side. 2A, 2B, 2C, and 2D are a front view, a bottom view, a side view, and a rear view of the planar illumination device shown in FIG. 1, respectively. FIG. 3 is a partial cross-sectional view of an embodiment of the planar lighting device shown in FIG. In addition, in the following figures including these figures, in order to facilitate understanding, they are shown enlarged in the direction of the thickness of the planar lighting device.
As shown in FIG. 1 and FIGS. 2A to 2D, the planar illumination device 10 includes a plurality of linear light sources 12 and emits uniform light from a rectangular light exit surface 14 a. 14, a housing 16 in which the lighting device main body 14 is housed and a rectangular opening 16a is formed on the light emitting surface 14a side (surface side), and the housing 16 is opposite to the light emitting surface 14a. An inverter storage unit 20 that stores a plurality of inverter units 18 that are attached to the side (rear surface side) and that is used to light each of the plurality of linear light sources 12, and a plurality of inverter units 18 that are stored in the inverter storage unit 20 And a power source 38 (see FIG. 6) for lighting the plurality of linear light sources 12 respectively.

Here, the illuminating device main body 14 is for emitting uniform light from the rectangular light emitting surface 14a. As shown in FIGS. 3, 4 and 5A, basically, A plurality of linear light sources 12 and a rectangular light emission surface 22a are formed on the side of the light emission surface 14a, and a plurality of parallel grooves 22b that respectively accommodate the plurality of linear light sources 12 are formed on the back side thereof. A light guide plate 22 in which the thinnest portion 22c having the thinnest thickness from the light exit surface 22a toward the back side is formed between the parallel grooves 22b, and the light guide plate 22 is disposed on the light exit surface 22a side. An optical member unit 24 having a rectangular plane that forms the exit surface 14a, and a reflecting member 26 disposed along the back surface 22d of the light guide plate 22 are provided.
4 shows only the unit light guide plate 23 having one parallel groove 22b as one unit constituting the light guide plate 22, but as shown in FIG. The illuminating device main body 14 is formed by a light guide plate 22 formed by connecting a plurality of unit light guide plates 23, and an optical member unit 24 disposed on the light guide plate 22 is also substantially the same as the light exit surface 22 a of the light guide plate 22. Needless to say, they have the same size (area).

The linear light source 12 is disposed in the plurality of parallel grooves 22 b of the light guide plate 22 and is connected to the inverter unit 18. The linear light source 12 used in the present invention is a linear, that is, a thin rod-shaped cold cathode tube (CCFL: see FIG. 6), and is used to illuminate a surface. Here, a cold cathode tube is used as the linear light source 12, but the present invention is not limited to this, and the linear light source 12 may be any rod-shaped light source (linear light source), In addition to the cold cathode fluorescent lamp (CCFL), for example, a normal fluorescent tube (hot cathode fluorescent tube; HCFL), an external electrode tube (EEFL), a light emitting diode (LED), a semiconductor laser, or the like can be used. When an LED is used as the linear light source 12, a cylindrical or prismatic transparent light guide having the same length as the parallel grooves 22b of the light guide plate 22 is used, and the upper surface of the light guide and You may use LED light source which arrange | positions LED in a bottom face, injects the light of LED from the upper surface and bottom face of a light guide, and inject | emits from the side surface of a light guide.
The inverter unit 18 and the power source 38 (see FIG. 6) for turning on and off the plurality of linear light sources 12 will be described later.

As shown in FIG. 5A, the light guide plate 22 is configured by connecting a plurality of unit light guide plates 23 to each other.
The unit light guide plate 23 is made of a transparent resin, and as shown in FIG. 5B, a rectangular individual light exit surface 23a, a thick portion 23b parallel to one side thereof, and both sides of the thick portion 23b. A thin end portion 23c formed parallel to one side, and the thickness is reduced from the thick portion 23b toward the thin end portions 23c on both sides in a direction perpendicular to the one side, constituting the back surface 22d of the light guide plate 22; It has an inclined back surface portion 23e that forms a curved inclined surface 23d, and a parallel groove 22b that is formed parallel to one side of the thick portion 23b and that houses the light source 12. That is, the unit light guide plate 23 includes one parallel groove 22b, and has an individual light exit surface 23a having the same length as the light exit surface 14a of the light guide plate 22 in a direction parallel to the parallel groove 22b. .
Further, in the unit light guide plate 23, a connection surface with the adjacent unit light guide plate 23, that is, a surface facing the adjacent unit light guide plate 23 (hereinafter referred to as an end surface 23f) has an uneven shape. The shape of the end face 23f will be described in detail later.
As the structures and materials of the unit light guide plate 23 and the light guide plate 22, those disclosed in [0036] to [0039] of Japanese Patent Application Laid-Open No. 2005-23497 related to the applicant's application can be applied.

The parallel grooves 22b may have two hyperbolic shapes that intersect each other as shown in the illustrated example. However, any shape having a luminance uniforming effect such as a triangular shape, a U shape, or a parabolic shape may be used. A thing disclosed in [0040] to [0058] of Japanese Patent Application Laid-Open No. 2005-23497 related to the application of the present applicant can be applied.
Further, the inclined surface 23d may be formed of a curved surface as in the illustrated example, or may be a flat surface having a constant inclination angle with respect to the individual light exit surface 23a, or a plurality of inclination angles that gradually change. These curved surfaces and planes need to be parallel to the parallel grooves 22b.
The profile of the cross section of the parallel groove 22b and the inclined surface 23d perpendicular to the parallel groove 22b is not particularly limited, but the luminance uniformity of the illumination light emitted from the individual light emission surface 23a is high, and If there is little decrease in luminance, the present invention is not particularly limited, but the one disclosed in Japanese Patent Application No. 2004-325251 relating to the application of the present applicant can be applied.

The unit light guide plate 23 allows illumination light emitted from the linear light source 12 accommodated in the parallel groove 22b to enter, and is inclined in a direction parallel to the individual light emission surface 23a from the thick portion 23b toward the thin end portion 23c. The illumination light propagated through the back surface portion 23e and the illumination light reflected by the inclined surface 23d and the reflecting member 26 disposed along the inclined surface 23d and along the inclined surface 23d constituting the back surface are uniformly distributed from the individual light emitting surface 23a. Is emitted as a simple illumination light.
Thus, uniform illumination light is emitted from the light exit surface 22a of the light guide plate 22 to which the plurality of unit light guide plates 23 are connected.
As shown in FIG. 5A, the light guide plate 22 has a structure in which the unit light guide plates 23 adjacent to each other in the direction orthogonal to the parallel groove 22b are connected to each other by the thin end portions 23c. The connecting portion forms the thinnest portion 22 c of the light guide plate 22. In this case, it goes without saying that the individual light exit surfaces 23a of the plurality of unit light guide plates 23 are connected to each other, and the light guide plate 22 forms a uniform light exit surface 22a.

In this embodiment, the light guide plate 22 is formed by connecting a plurality of unit light guide plates 23. However, the present invention is not limited to this, and a plurality of unit light guide plates 23 are connected. A plurality of integrally formed light guide plate connectors may be connected to form a large light guide plate having a large area of light exit surface 22a. In other words, the unit light guide plate may have a shape in which a plurality of parallel grooves in which light sources are arranged is formed, and a plurality of unit light guide plates may be connected to form a light guide plate having a flush light exit surface.
By integrally molding the plurality of unit light guide plates in this way, it is possible to reduce the number of connecting portions where bright lines are generated, and to emit uniform illumination light from the light exit surface.
In addition, the plurality of unit light guide plates 23 or the light guide plate coupling bodies are orthogonal to the parallel grooves 22b between the adjacent unit light guide plates 23 or the thin end portions 23c of the unit light guide plates 23 positioned at the ends of the light guide plate coupling bodies. The light emitting surface 22a may be enlarged by connecting in the direction, and the light emitting surface 22a may be increased in area, or the end portions orthogonal to the adjacent unit light guide plate 23 or the thin end portion 23c of the light guide plate connector may be connected in parallel. It may be connected in a direction parallel to the groove 22b to increase the size and the light emission surface 22a to have a large area, or these may be performed simultaneously to connect in a direction parallel to and perpendicular to the parallel groove 22b. The light emitting surface 22a may be increased in size and the area may be increased. At this time, the uniform planar light emission surfaces of the plurality of unit light guide plates 23 or the light guide plate connector are connected to each other, and the light guide plate 22 forms a uniform planar light emission surface 22a. Needless to say. In this case, the linear light source 12 is preferably a linear light source having the length of the parallel groove 22b of the light guide plate 22 connected to the unit light guide plate 23 or the light guide plate connector. It is preferable that the optical member unit 24 disposed in the upper part has substantially the same size (area) as the light exit surface 22a of the light guide plate 22.

The optical member unit 24 makes the uniform illumination light emitted from the light emission surface 22a of the light guide plate 22 more uniform, and emits the illumination light with further improved uniformity from the light emission surface 14a of the illumination device body 14. As shown in FIGS. 3 and 4, a microprism array parallel to the parallel grooves 22b of the light guide plate 22 and forming the light emission surface 14a is formed and emitted from the light emission surface 22a of the light guide plate 22. A prism sheet 24a for improving brightness by improving the condensing property of the illumination light,
A diffusion sheet 24b (diffusing material) that diffuses and equalizes the illumination light emitted from the light exit surface 22a of the light guide plate 22 and the luminance unevenness of the illumination light emitted from the light exit surface 22a of the light guide plate 22 are reduced. A transparent sheet 25a and a transmittance adjusting member 24c provided on the surface of the transparent sheet 25a according to the luminance unevenness and including a large number of transmittance adjusting bodies 25b made of a diffuse reflector.

The transmittance adjusting member 24c is preferably provided on the side close to the light exit surface 22a of the light guide plate 22. However, the arrangement order and the number of arrangement of the prism sheets 24a and the diffusion sheets 24b are not limited. The prism sheet 24a, the diffusion sheet 24b, and the transmittance adjusting member 24c used in the member unit 24 are not limited to those described above, and the illumination light emitted from the light exit surface 22a of the light guide plate 22 can be made more uniform. Any optical member may be used as long as it can be used. The prism sheet 24a may be disposed between the light guide plate 22 and the reflecting member 26 on the back surface 22d side, or a prism row may be formed on the back surface 22d of the light guide plate 22 itself.
The optical members used in the optical member unit 24 having the prism sheet 24a, the diffusion sheet 24b, and the transmittance adjusting member 24c are described in [0028] to [0033] of Japanese Patent Application Laid-Open No. 2005-23497 related to the present applicant. What is disclosed can be applied.

The reflecting member 26 used in the illuminating device main body 14 is disposed along the back surface 22 d of the light guide plate 22 and is for improving the utilization efficiency of the illumination light emitted from the linear light source 12. A reflective sheet 26a that is disposed along the back surface 22d of the light guide plate 22 excluding the parallel grooves 22b on the back side where the grooves 22b are formed, reflects light leaking from the back surface of the light guide plate 22 and reenters the light guide plate 22; The light guide plate 22 is arranged on the back surface of the linear light source 12 so as to block the parallel grooves 22b of the light guide plate 22 between the adjacent reflection sheets 26a. And a reflector 26b for making the reflected light incident from the side wall surface of 22b.
The illumination device body 14 is basically configured as described above.

  On the other hand, as shown in FIG. 3, the housing 16 accommodates and supports the illuminating device main body 14, and is sandwiched and fixed from the light emitting surface 14a side and the reflecting member 26 side, and the upper surface is open. The lighting device body 14 is housed and supported from above, and the lower housing 30 that covers the four side surfaces of the lighting device body 14 and the rectangular light emission surface 14a of the lighting device body 14 have an opening 16a on the top surface. A rectangular opening is formed, a lower surface is opened, and an upper housing 32 that covers the lighting device main body 14 and the lower housing 30 in which the lighting device main body 14 and the lower housing 30 are covered, including the four sides thereof, and a lower portion A concave (U-shaped) folding member 34 inserted between the side wall of the housing 30 and the side wall of the upper housing 32, and the bottom surface of the lower housing 30 are disposed on the back surface 22d of the light guide plate 22. 26 is supported through The entire apparatus main body 14 also has a light guide plate supporting member 36 for supporting. Although not shown in FIG. 3, an inverter storage unit 20 (see FIG. 2) that stores a plurality of inverter units 18 is attached to the back side of the lower housing 30.

Here, as a method for joining the lower housing 30 and the folding member 34, and a method for joining the folding member 34 and the upper housing 32, various known methods such as a method using bolts and nuts, a method using an adhesive, and the like. Can be used.
The upper housing 32 is larger than the lower housing 30 and at least outer wall surfaces at both ends of the lower housing 30 parallel to the parallel grooves 22b of the light guide plate 22 of the illuminating device body 14 or the linear light source 12 housed therein. The folding members 34 need to be disposed in the gaps between the inner wall surfaces of the upper casing 32 and the upper casing 32 facing each other. The folding members 34 are arranged on the four sides of the casing 16 with respect to the lower casing 30. You may arrange | position between a side wall and the side wall of the upper housing | casing 32. FIG. Moreover, you may attach the reinforcement member which reinforces the recessed part of the concave folding member 34. FIG.
By disposing the folding member 34 in this way, the rigidity of the housing 16 can be increased, and light can be emitted uniformly and efficiently. On the other hand, the light guide plate 22 is likely to warp due to the presence of the parallel grooves 22b. Even so, it is possible to correct the warp or prevent the light guide plate 22 from warping, and to obtain good optical characteristics without causing uneven brightness. Moreover, the rigidity of the housing | casing 16 can be made higher by attaching the reinforcement member which reinforces the recessed part of the folding | turning member 34, and it can prevent more appropriately that the light guide plate 22 warp. Thereby, better optical characteristics can be obtained.

The light guide plate support 36 is formed of a resin such as polycarbonate. In the illustrated example, the light guide plate support 36 is a convex member having a shape obtained by inverting the shape of the back surface 22d of the thinnest portion 22c of the light guide plate 22. Although it arrange | positions at predetermined intervals for every thinnest part 22c of the light-guide plate 22 along the back surface 22d of the light-guide plate 22 at the bottom part of the lower housing | casing 30, this invention is not limited to this, A light-guide plate It may be a continuous member in which convex portions having a shape obtained by inverting the shape of the back surface 22d of 22 are provided at a predetermined interval.
Note that the housing 16 has a stopper such as an L-shaped metal fitting that joins the four corners, rubber between the prism sheet 24a of the lighting device main body 14 and the peripheral edge of the opening of the upper housing 32, or the like. There may be provided an elastic member made of the above elastic material, a protective member for protecting the entire upper surface of the prism sheet 24a of the illuminating device body 14, or the like.
The housing 16 is basically configured as described above.

Next, driving devices for the plurality of linear light sources 12 housed in the parallel grooves 22b of the light guide plate 22 of the illuminating device body 14 will be described.
The driving device 37 shown in FIGS. 6A and 6B drives the linear light source 12 such as a plurality of CCFLs, that is, turns on and off, and drives the illumination of the planar lighting device 10. A plurality of inverter units 18 respectively connected to the linear light sources 12 such as a plurality of CCFLs, and a power source 38 to which the plurality of inverter units 18 are connected. FIG. 6B shows a block diagram of the drive unit 37 for lighting the linear light source 12 such as one CCFL in order to show the detailed configuration of the inverter unit 18.
The power source 38 is a DC power source that outputs a DC voltage, for example, a DC voltage of 24V DC. This DC voltage is supplied to each of the plurality of inverter units 18 connected to the power source 38.

  The inverter unit 18 is connected to the drive circuit 18a that generates a primary AC signal having a predetermined frequency of a predetermined voltage (for example, 650 Vp-p) from the DC voltage supplied from the power supply 38, and the linear light source 12, and is connected to the drive circuit. A transformer 18b that boosts the primary AC signal generated in 18a to a high-voltage secondary AC signal (for example, 6500 Vp-p, 1000 to 2400 Vrms) necessary for lighting the linear light source 12 such as CCFL; The tube current detection circuit 18c for detecting the tube current connected to the linear light source 12 such as CCFL and the tube current output from the tube current detection circuit 18c are fed back, and the drive circuit 18a receives the primary AC signal. A voltage-controlled oscillation circuit 18d that oscillates a clock (fundamental wave) having a predetermined frequency for generation according to the fed-back tube current; That.

In the present invention, by configuring the drive device 37 of the linear light source 12 in this way, the plurality of linear light sources 12 are lit simultaneously and uniformly efficiently, stably and safely, with uniform brightness. Can emit light.
In the present invention, the plurality of linear light sources 12 are turned on at the same time. However, only a part of them may be turned on by the inverter unit 18 or these may be switched.
The linear light source driving device and the planar illumination device are basically configured as described above.

  Although the planar lighting device 10 of the above-described embodiment is provided with the inverter storage portion 20 on the back side of the housing 16 and stores a plurality of inverter units 18, the planar lighting device of the present invention is limited to this. 7, between the lower housing 30 and the upper housing 32 in the periphery of the opening 16 a of the housing 16 on the side orthogonal to the linear light source 12, as in the planar illumination device 11 shown in FIG. 7. A space may be provided to serve as the inverter storage unit 20, and a plurality of inverter units 18 may be stored. By doing so, the back surface of the planar illumination device 11, that is, the back surface of the housing 16 can be flattened, and attachment to a ceiling or a wall surface can be facilitated.

  Next, several embodiments of the method for connecting the unit light guide plates 23 in the planar illumination device 10 of the present invention will be described in detail with reference to FIGS.

FIG. 8A is a schematic top view illustrating a connecting portion between two unit light guide plates 23 adjacent to the light guide plate 22 of the planar illumination device 10.
In the end face 23f of the unit light guide plate 23 of the light guide plate 22 of the present embodiment, rectangular convex portions 50 having the same shape are formed at regular intervals, and the space between the convex portions 50 and 50 is a rectangular shape. It becomes the recessed part 52 of this. Further, the end surface 23′f of the unit light guide plate 23 ′ adjacent to the unit light guide plate 23 has a shape obtained by inverting the shape of the end surface 23f of the unit light guide plate 23, that is, the unit light guide plate 23 and the unit light guide plate 23 ′. When connected, a rectangular concave portion 54 is formed on the end surface 23′f of the unit light guide plate 23 ′ corresponding to the arrangement of the convex portions 50 on the end surface 23f of the unit light guide plate 23. A rectangular convex portion 56 is formed on the end surface 23′f of the unit light guide plate 23 ′ corresponding to the concave portion 52 of the end surface 23f of the end surface 23f of the unit light guide plate 23 ′. Thus, the end surface 23f of the unit light guide plate 23 and the end surface 23′f of the adjacent unit light guide plate 23 ′ are in a male-female relationship. In other words, the outline of the end surface 23f of the unit light guide plate 23 in the plane parallel to the light exit surface and the outline of the end surface 23'f of the adjacent unit light guide plate 23 'have the same shape.

  Next, FIG. 8B is a schematic top view showing an emission state of a light beam from the light guide plate 22, and FIG. 8C is a guide in which a diffusion sheet 24 b is arranged on the light emission surface of the light guide plate 22. It is a schematic top view which shows the emission state of the light beam from an optical plate. For comparison, FIG. 11A is a schematic top view showing a light emission state from a light guide plate 100 having a flat end surface, and FIG. 11B is a diagram in FIG. It is a schematic top view which shows the emission state of the light beam from the light guide plate 100 which has arrange | positioned the diffusion sheet 24b on the light emission surface of the used light guide plate 100. FIG.

When the end surface 102f of the unit light guide plate 102 that is a connecting portion between the adjacent unit light guide plates 102 has a flat shape, the light beam emitted from the linear light source is reflected on the unit light guide plate 102 as shown in FIG. Leakage occurs between the gaps of the connecting portions, that is, between the end surface of the unit light guide plate 102 and the end surface 102′f of the unit light guide plate 102 ′, and a linear bright line 104a is generated.
By covering the light emitting surface of the light guide plate 100 with the diffusion sheet 24b, the bright line 104a is dispersed, and as a result, the change in luminance around the bright line generating part can be moderated, but as shown in FIG. Thus, since the bright line 104b becomes conspicuous, it is difficult to make the luminance unevenness inconspicuous even when covered with the diffusion sheet 24b.

In the present invention, as shown in FIG. 8A, the end surface 23f of the unit light guide plate 23 has an uneven shape, specifically, a shape in which the convex portion 50 and the concave portion 52 are repeatedly formed, and is adjacent. The shape of the end surface 23′f of the unit light guide plate 23 ′ is a shape in which a concave portion 54 and a convex portion 56 corresponding to the concave and convex shape of the end surface 23f are formed.
As shown in FIG. 8B, the illumination light emitted from the light exit surface 22a of the light guide plate 22 is a unit light guide plate 23 in which the light beam emitted from the linear light source is adjacent to the end surface 23f of the unit light guide plate 23. Since it leaks from the space between the 'end surface 23'f, a rectangular wave type bright line 40a is generated. When the diffusion sheet 24b is disposed on the light exit surface 22a of the light guide plate 22, as shown in FIG. 8C, the bright lines 40a are dispersed to become the bright lines 40b, and the luminance unevenness can be made inconspicuous. . Further, as in the present embodiment, the end face 23f is formed in a concavo-convex shape so that the unit light guide plates having flat end faces as shown in FIGS. 11 (a) and 11 (b) are connected to each other. Thus, since the region where the bright line 40a is dispersed is further widened, the change in luminance around the bright line generation portion can be made more gradual. That is, the luminance difference between the light leaking from between the end faces and the light transmitted through the light guide plate can be gradually reduced in a wider area. As a result, the luminance unevenness caused by the bright lines is hardly visually recognized.
Further, in FIG. 8C, only the diffusion sheet 24b is arranged, but in addition, an optical member unit 24 including the prism sheet 24a and the transmittance adjusting member 24c as shown in FIGS. It is more preferable to arrange.

According to the present invention as described above, the uneven illumination can be reduced by dispersing the bright lines generated at the connecting portions of the unit light guide plates 23.
Furthermore, since the end surface 23f which is a connection part of the unit light guide plates 23 has an uneven shape, when connecting the unit light guide plates 23 to each other, in the extending direction of the end surfaces 23f (the extending direction of the parallel grooves). Deviation can be prevented, and the alignment accuracy of the connecting portion is improved.

Here, in the said embodiment, although the end surface of the unit light-guide plate was made into the rectangular uneven | corrugated shape, this invention is not limited to this, It can be set as various uneven | corrugated shapes.
FIGS. 9A to 9C are pattern examples when the shape of the end surface 23f of the unit light guide plate 23, which is a connecting portion of the unit light guide plates that can be used in the present invention, is viewed from the light exit surface side. .
As shown in FIG. 9 (a), the convex portion 60 of the end surface 23f of the unit light guide plate 23 has a triangular shape and a saw shape in which a plurality of convex portions 60 are continuously formed, and the end surface 23 ′ of the unit light guide plate 23 ′. The convex portion 62 of f may have the same shape, and the unit light guide plate 23 and the unit light guide plate 23 ′ may be adjacent to each other by disposing the end surface 23f and the end surface 23′f to face each other.
Further, as shown in FIG. 9B, the convex portion 64 of the end face 23f of the unit light guide plate 23 has a parabolic shape, and is formed into a corrugated shape in which a plurality of convex portions 64 are continuously formed. The convex portion 66 of the end surface 23′f may have the same shape, and the unit light guide plate 23 and the unit light guide plate 23 ′ may be adjacent to each other by disposing the end surface 23f and the end surface 23′f to face each other.
Further, as shown in FIG. 9C, the convex portions 68 of the end surface 23f of the unit light guide plate 23 are L-shaped, the plurality of convex portions 68 are arranged at regular intervals, and the end surface 23 of the unit light guide plate 23 ′. The unit light guide plate 23 and the unit light guide plate 23 ′ may be adjacent to each other by arranging the end surface 23 f and the end surface 23 ′ f to face each other with the same shape for the convex portion 70 of “f”.
In addition, this invention is not limited to the said shape, The end surface of a unit light-guide plate can be made into various uneven | corrugated shape.
In addition, when the light guide plates are bonded to each other using an adhesive or the like, the occurrence of luminance unevenness at the connection portion can be reduced by using such an uneven shape.

Moreover, in the pattern of FIG. 9, the adjacent unit light-guide plate has a symmetrical unevenness | corrugation from the point that the clearance gap between the connection parts of an adjacent unit light-guide plate can be made smaller, and a bright line generation | occurrence | production part can be made small. The outline of the end face 23f of the unit light guide plate 23 and the outline of the end face 23'f of the adjacent unit light guide plate 23 'in the plane parallel to the exit surface exemplify patterns having the same shape. It is not limited to. For example, when the optical member unit 24 is arranged, a pattern that is asymmetrical to the left and right may be used as long as the bright line can be dispersed. That is, the outline of the end surface 23f of the unit light guide plate 23 in a plane parallel to the light exit surface may be different from the outline of the end surface 23'f of the adjacent unit light guide plate 23 '.
In particular, when the light emitted from the end face of one unit light guide plate and the brightness of the light emitted from the end face of the other unit light guide plate are different, by adjusting the light emitted from the end face according to the shape of the end face, It is possible to prevent uneven brightness from occurring at the connection portion.

If the end face 23f of the unit light guide plate 23 is connected in such a shape as described above, the bright lines are dispersed as shown in FIG. 8C when the diffusion sheet 24b is arranged. The width of the bright line is widened and blurred, and a clear bright line is not visually recognized.
Thereby, the light with reduced luminance unevenness can be emitted from the light exit surface of the illuminating device main body.

In the above example, the concave / convex shape of the end surface 23f of the unit light guide plate 23 is an uneven shape when viewed from the individual light exit surface 23a side of the unit light guide plate 23. When viewed from a direction parallel to the extending direction of the parallel grooves 22b of the light guide plate 22, the shape may be uneven.
FIG. 10 is a schematic cross-sectional view showing an embodiment of a light guide plate having an uneven shape when viewed from a direction parallel to the extending direction of the parallel grooves of the light guide plate.
In FIG. 10, a convex portion 80 is formed on the individual light exit surface 23a side (upper side in FIG. 10) of the end surface 23f of the unit light guide plate 23, and a concave portion 82 is formed on the inclined surface 23d side (lower side in FIG. 10). A concave portion 84 is formed on the individual light exit surface 23′a side of the end surface 23′f of the unit light guide plate 23 ′ adjacent to the light guide plate 23, and a convex portion 86 is formed on the inclined surface 23d side. Here, the convex part 80, the recessed part 82, the recessed part 84, and the convex part 86 are extended in the extension direction of the parallel groove | channel 22b. That is, the convex portion 80, the concave portion 82, the concave portion 84, and the convex portion 86 have the same cross section perpendicular to the extending direction of the parallel groove 22b.
Such unit light guide plates 23 and 23 ′ are arranged by engaging the convex portion 80 and the concave portion 84, and the concave portion 82 and the convex portion 86. Thus, by arranging the unit light guide plate 23 and the unit light guide plate 23 ′ adjacent to each other, the individual light exit surface 23a and the individual light exit surface 23′a constitute a flush light exit surface 22a.
As described above, the light exit surface of the light guide plate can also be obtained by forming the end surface of the unit light guide plate into a shape having irregularities when viewed from the direction parallel to the extending direction of the parallel grooves and fitting the adjacent unit light guide plates. By disposing the diffusion sheet 24b on the upper side, as in the case of FIG. 8A, it is possible to disperse the bright lines generated at the connecting portions of the unit light guide plates, and to reduce the visibility of luminance unevenness.

  Further, in the present invention, the diffusion sheet 24b is arranged over the entire light guide plate 22. However, if it is difficult to suppress the luminance unevenness due to the bright lines alone, the diffusion sheet 24b is appropriately and partially applied to the clear portion of the bright lines. Further, a diffusion material may be arranged. For example, it is possible to further reduce the luminance unevenness of the illumination light by further disposing a diffusing material at positions on both ends of the bright line.

  In the above embodiment, a plurality of unit light guide plates are connected to each other, and the thin end portion serving as the connecting portion has a shape having irregularities, but the present invention is not limited to this. For example, as described above, in the case of a configuration in which a plurality of light guide plate assemblies integrally formed with a plurality of unit light guide plates are connected, an end surface that becomes a connection portion between the light guide plate connector and the light guide plate connector is an uneven shape. By doing so, the uneven brightness of the illumination light can be reduced.

  As described above, the planar illumination device and the liquid crystal display device of the present invention have been described in detail. However, the present invention is not limited to the above embodiments, and various improvements and modifications can be made without departing from the gist of the present invention. Of course it is also good.

It is a schematic perspective view which shows the external appearance seen from the light-projection surface side of one Embodiment of the planar illuminating device of this invention. (A), (b), (c), and (d) are the front view of the planar illuminating device shown in FIG. 1, the side view of a longitudinal direction, the side view of a transversal direction, and a rear view, respectively. It is a fragmentary sectional view of one Embodiment of the planar illuminating device shown in FIG. It is a schematic perspective view of the planar illuminating device main body corresponding to one unit light-guide plate used for the planar illuminating device shown in FIG. (A) is a schematic perspective view of the light-guide plate used for the planar illuminating device shown in FIG. 3, (b) shows the cross-sectional shape of one unit light-guide plate of the planar illuminating device main body shown in FIG. FIG. (A) is the wiring diagram of one Embodiment of the drive device of the linear light source used for the planar illuminating device shown in FIG. 2, (b) is the block of the drive device of the linear light source shown to (a). FIG. It is a schematic block diagram which shows other embodiment of the planar illuminating device of this invention. (A) is a figure which shows an example of the shape of the connection part of the light-guide plate of a planar illuminating device, (b) is a figure which shows an example of the bright line in the connection part of the light-guide plate shown to (a), (C) is a figure which shows an example of the bright line at the time of arrange | positioning a diffusion material to the light-guide plate shown to (a). It is a figure which shows another example of the shape of the connection part of the light-guide plate of the planar illuminating device of this invention. It is a figure which shows the cross-sectional shape of the connection part of the light-guide plate of the planar illuminating device of this invention. (A) is a figure which shows an example of the bright line in the connection part of the light guide plate of the conventional planar illuminating device, (b) is an example of the bright line at the time of arrange | positioning a diffusion material to the light guide plate shown to (a). FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 11 Planar illuminating device 12 Linear light source 14 Illuminating device main body 14a Light emission surface 16 Housing | casing 16a Opening part 18 Inverter unit 18a Drive circuit 18b Transformer 18c Tube current detection circuit 18d Voltage control oscillation circuit 20 Inverter accommodating part 22,100 Light guide plate 22a Light exit surface 22b Parallel groove 22c Thinnest portion 22d Back surface 23, 102 Unit Light guide plate 23a Individual light exit surface 23b Thick portion 23c Thin end portion 23d Inclined surface 23e Inclined back surface portion 23f End surface 24 Optical member unit 24a Prism sheet 24b Diffusion sheet 24c Transmittance adjusting member 25a Transparent sheet 25b Transmittance adjusting body 26 Reflecting member 26a Reflecting sheet 26b Reflector 30 Lower housing 32 Upper housing 34 Folding member 36 Light guide plate support member 37 Drive device 38 Power supply

Claims (5)

A plurality of unit light guide plates each having a linear light source and an individual light exit surface are provided, the unit light guide plates are disposed adjacent to other unit light guide plates, and are flush with the individual light exit surfaces of the plurality of unit light guide plates. A light guide plate that diffuses light emitted from the linear light source and emits the light from the light exit surface, and a diffusion material that diffuses illumination light emitted from the light exit surface of the light guide plate A planar lighting device comprising:
Of the unit light guide plate, the end face facing the unit light guide plate adjacent in the cross section in the direction parallel to the light exit plane, the repeating pattern of irregularity is formed over the entire area, the repetitive pattern of this unevenness, A planar illumination device characterized by being combined with a repeating pattern of irregularities formed on end faces of adjacent unit light guide plates . 2. The planar lighting device according to claim 1, wherein the unit light guide plate has an uneven shape of an end surface facing an adjacent unit light guide plate, which is a shape obtained by inverting the uneven shape of an end surface of the adjacent unit light guide plate.   The planar illumination device according to claim 1, wherein the outline of the end surface of the unit light guide plate has a shape different from the outline of the end face of the unit light guide plate adjacent thereto. The planar lighting device according to any one of claims 1 to 3 , wherein the unit light guide plate has a plurality of parallel grooves in which the linear light sources are arranged on a surface opposite to the unit light emission surface.   The planar illumination device according to any one of claims 1 to 4, wherein a shape of a convex portion of the end face of the unit light guide plate is an L shape.

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