JP2007335152A - Planar lighting apparatus, manufacturing method therefor, and arrangement method for transmission factor adjustor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a planar lighting apparatus which has transmission factor adjustors arranged on a light outgoing surface of a light guide plate, reduces its thickness and weight, and has a capability to reduce variation in the luminance without reduction in the average luminance of the incoming light. <P>SOLUTION: When a pattern density at the predetermined position (x, y) of a transmission factor adjustor is ρ(x, y), and a relative luminance is F(x, y) on the light outgoing from the predetermined position (x, y) of a light outgoing surface on the planar lighting apparatus, in case where the transmission factor adjustor with a pattern density of ρb is arranged, maximum value of the relative luminance is F<SB>max</SB>, and minimum value of the relative luminance is F<SB>min</SB>under the condition of 0<c≤0.3 and 0.5≤ρb; many transmission factor adjustors to be arranged on the light outgoing surface of the light guide plate are attached to the positions where the relationship between the relative luminance F(x, y) and pattern density ρ(x, y) satisfies the equation: ρ(x, y)=cäF(x, y)-F<SB>min</SB>}/(F<SB>max</SB>-F<SB>min</SB>)+ρb. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention provides a planar illumination device that illuminates the interior and exterior of a light guide plate, having a transmittance adjusting member composed of a transmittance adjusting body that makes light emitted from the light emitting surface of the light guide plate uniform emitted light, or The present invention relates to a planar lighting device used as a backlight for a liquid crystal display panel, an advertising panel, an advertising tower, a signboard, and the like, a method for arranging the transmittance adjusting body, and a method for manufacturing the planar lighting device.

A liquid crystal display device uses a backlight unit that irradiates light from the back side of a liquid crystal panel (LCD) to illuminate the liquid crystal panel. The backlight unit uses a light source for illumination, a light guide plate that diffuses light emitted from the light source and irradiates the liquid crystal panel, and a component such as a prism sheet and a diffusion sheet that uniformizes the light emitted from the light guide plate. Composed.
As such a backlight unit, for example, a backlight unit disclosed in Patent Document 1 is known.

FIG. 21 is a schematic cross-sectional view of the surface light source device disclosed in Patent Document 1.
In the surface light source device (backlight unit) shown in the figure, after the fluorescent lamp 202 is embedded in the light guide plate 200, the reflection sheet 204 is disposed on the back surface of the light guide plate 200, and the transmitted light amount correction sheet is provided on the exit surface of the light guide plate 200. 206, the light diffusion plate 208 and the prism sheet 210 are laminated.
The light guide plate 200 has a substantially rectangular shape, and is formed using a resin in which fine particles that diffuse illumination light are dispersed and mixed. In addition, the upper surface of the light guide plate 200 is flat and assigned to the exit surface. Further, a groove 200a having a U-shaped cross section for embedding the fluorescent lamp 202 is formed on the back surface (surface opposite to the light exit surface) of the light guide plate 200. The light guide plate 200 has a light exit surface directly above the fluorescent lamp 202. The light quantity correction surface 200b that prompts the emission of illumination light is formed.

  As described above, in Patent Document 1, the light guide plate 200 is formed by mixing fine particles, and the illumination light is corrected by the light amount correction surface 200b formed on a part or all of the emission surface except directly above the fluorescent lamp 202. It is described that by promoting the emission, the entire thickness can be reduced and unnatural luminance unevenness of the emitted light can be reduced.

Patent Document 2 discloses a backlight of a liquid crystal display device that can realize a reduction in size and weight of the liquid crystal display device and reduction in cost and power consumption without reducing the amount of backlight irradiation. For this purpose, a rectangular irradiation surface, a rectangular cross section grooved in parallel with the long side at the center of the short side, and a groove with a rectangular cross-section for inserting the light source, facing both sides of the long side across this groove A light guide plate having a back surface formed so that the plate thickness is gradually reduced is described.
Further, in Patent Document 3, the frame of the liquid crystal display device can be narrowed and the thickness can be reduced, and in order to obtain a bright backlight unit with good light utilization efficiency, the width direction of the concave portion for arranging the light source is described. A light guide (light guide plate) is described in which the parallel cross-sectional shape is a parabolic shape with the depth direction as the main axis.

  Further, in Patent Document 4, in order to keep the in-plane brightness of the display panel uniform and to provide high-intensity illumination, a plurality of refractive indexes are sequentially increased on the C-shaped highly reflective layer. A light guide plate is disclosed in which the plate-like optical waveguide layers are stacked and the light diffusion layer is brightened by the light emitted from the respective light emission end faces. Here, the recess for arranging the light source has a triangular shape.

  In a planar illumination device using such a light guide plate, luminance distributions such as bright lines and dark lines occur, and various methods have been proposed for improving this. (For example, Patent Document 5 and Patent Document 6)

  In Patent Document 5, as shown in FIG. 19, a dot-shaped print portion that prevents light transmission is formed on the surface, and the density of the print portion is an area where the cold cathode fluorescent lamp 36 is positioned directly below. A liquid crystal display device is described having a diffuser plate that is dense at 39A and sparse as it moves away from the region 39A. With such a diffusion plate, the amount of light emitted to the diffusion plate side is supposed to be uniform over the entire surface of the diffusion plate.

  Patent Document 6 describes a surface light source device in which a light amount adjustment layer for reflecting and scattering a part of light emitted from the upper surface on the surface facing the line light source and returning it to the light guide plate is described. Yes. It is described that the light amount adjustment layer may be formed so that the area ratio decreases as the distance from the line light source increases, or may be formed only in the vicinity of the line light source. In addition, as a material for the transparent flat plate, a translucent resin or film is used, but a light diffusion plate may be used to smooth the intensity distribution of light emitted from the light guide plate and the line light source to the upper surface. It is described as good.

As described above, Patent Document 5 and Patent Document 6 describe various configurations for reducing luminance unevenness, but it is necessary to use a sufficiently thick diffusion plate for each configuration, and the device becomes thick and heavy. There is a problem that the luminance unevenness cannot be sufficiently reduced.
In order to solve such a problem, the present inventor arranges a transmittance adjusting body with a predetermined pattern density on a transparent film in Patent Document 7 in order to suppress generation of bright lines of a linear light source. A constructed transmittance adjuster unit has been disclosed.

Japanese Patent Laid-Open No. 9-304623 JP-A-8-62426 JP 10-1333027 A JP-A-5-249320 JP-A-5-127156 JP-A-6-235823 International Publication No. 2006/028080 Pamphlet

By using the transmittance adjusting body unit described in Patent Document 7, the light emitted from the light exit surface of the light guide plate can be made more uniform and emitted light with reduced luminance unevenness.
Further, it is described that the transmittance adjusting body unit described in Patent Document 7 can be directly disposed on the surface of the light guide plate in addition to being disposed on the transparent sheet, the diffusion film, and the prism sheet.
By arranging the transmittance adjusting body on the surface of the light guide plate in this way, it is possible to prevent the light guide plate and the transmittance adjusting body from being displaced, and it is also possible to obtain an effect that it is not necessary to align during manufacturing. it can.

  However, when the transmittance adjusting body is directly arranged on the light exit surface of the light guide plate, there is a problem that even if the transmittance adjusting body is arranged so as to satisfy the expression described in Patent Document 7, the luminance unevenness cannot be reduced suitably. is there.

  The object of the present invention is to solve the problems based on the above prior art, the transmittance adjusting body is disposed on the light exit surface of the light guide plate, is thin and lightweight, without reducing the average luminance of the incident light, Another object of the present invention is to provide a planar illumination device capable of reducing luminance unevenness, a method of arranging a transmittance adjusting body, and a method of manufacturing a planar illumination device using the same.

As a result of the present inventors diligently studying the transmittance adjusting body in order to solve the above problems, when the transmittance adjusting body is arranged on a transparent sheet or the like other than the light emitting surface of the light guide plate, the light emitting surface of the light guide plate When the transmittance adjusting body is directly arranged on the light exit surface of the light guide plate, the light totally reflected on the light exit surface of the light guide plate and the light exit surface are affected. It was found to affect both light. In other words, by arranging the transmittance adjusting body on the light emitting surface of the light guide plate, the light emitted from the light emitting surface is also totally reflected. The effect of reducing the light is greater than that of the case. For this reason, it has been found that when the transmittance adjusting body is arranged based on the formula described in Patent Document 7, the luminance reduction effect in the bright line portion becomes too large, and thus the luminance unevenness cannot be reduced.
Further, in order to reduce the luminance reduction effect in the bright line portion, when the transmittance adjusting body is arranged at a pattern density in which the value of c in the equation of Patent Document 7 is reduced, the arrangement density of the transmittance adjusting body is reduced, It has also been found that since the scattering effect by the transmittance adjusting body is reduced, the luminance distribution changes depending on the observation angle, and even when the luminance unevenness in the front direction is reduced, the luminance unevenness occurs depending on the observation angle. That is, it was also found that angle-dependent unevenness occurs.
Specifically, as shown in FIG. 20 (a), the light emitted from the planar illumination device emits light in the front direction (α direction in FIG. 20 (a)) and in the oblique direction (β direction in FIG. 20 (a)). ), As shown in FIG. 20B, light with uniform luminance is emitted in the α direction, but light with uneven luminance may be emitted in the β direction. I found out.
Further, it has been found that such angle-dependent unevenness can be reduced by arranging a transmittance adjusting body having a constant density as a base concentration over the entire light exit surface of the light guide plate.
That is, the present inventor arranges the transmittance adjusting body with a uniform density distribution in addition to the density distribution of the predetermined pattern according to the luminance distribution when the transmittance adjusting body is not arranged, thereby Even when a transmittance adjusting body is disposed on the light exit surface, it has been found that the luminance unevenness can be reduced, and the present invention has been achieved.

That is, in order to solve the above-described problem, a first aspect of the present invention is a planar illumination device that emits light from a light exit surface,
A flat light guide plate for emitting light emitted from the light source from the light exit surface;
A transmittance adjusting member that is directly disposed on the light exit surface and diffuses and emits the light emitted from the light exit surface;
The transmittance adjusting body member is composed of a number of transmittance adjusting bodies,
The pattern density at a predetermined position (x, y) of the transmittance adjusting body is ρ (x, y), and the light exit surface of the surface illumination device is predetermined when the transmittance adjusting body having a pattern density of ρb is arranged. When the relative luminance of the light emitted from the position (x, y) is F (x, y), the relationship between the relative luminance F (x, y) and the pattern density ρ (x, y) is as follows. Expression ρ (x, y) = c {F (x, y) −F _min } / (F _max −F _min ) + ρb
(Where c is 0 <c ≦ 0.3 and ρb satisfies 0.5 ≦ ρb, F _max is the maximum luminance of the relative luminance F (x, y), and F _min is (It is the minimum luminance of relative luminance F (x, y))
The planar illumination device characterized by satisfying the above is provided.

Furthermore, it is preferable that an optical member is disposed on the light exit surface side of the transmittance adjusting member.
The optical member preferably includes at least one of a diffusion film, a prism sheet, and a diffusion plate.

  The ρb preferably satisfies ρb ≦ 1.5.

In order to solve the above-described problem, the second aspect of the present invention is arranged on the light emitting surface of the light guide plate of the planar illumination device having at least a flat light guide plate that emits light from the light exit surface. A method for arranging a large number of transmittance adjusting bodies constituting a transmittance adjusting member that diffuses and emits light emitted from the light guide plate,
The pattern density of the transmittance adjusting body at a predetermined position (x, y) of the transmittance adjusting member is ρ (x, y),
When the relative luminance of light emitted from a predetermined position (x, y) on the light exit surface of the planar illumination device in which the transmittance adjusting body having a pattern density of ρb is arranged is F (x, y),
The relationship between the relative luminance F (x, y) and the pattern density ρ (x, y) is expressed by the following equation:
ρ (x, y) = c {F (x, y) −F _min } / (F _max −F _min ) + ρb
(In the formula, c satisfies 0 <c ≦ 0.3 and 0.5 ≦ ρb, F _max is the maximum luminance of the relative luminance F (x, y), and the relative luminance F (x, y) Is the minimum brightness)
The transmittance adjusting body is arranged directly on the light exit surface of the light guide plate so as to satisfy the above condition.

In the arrangement method of the transmittance adjusting body, the transmittance adjusting body having a pattern density of ρb is arranged on the entire light exit surface of the light guide plate,
Thereafter, it is preferable to arrange a transmittance adjusting body having a pattern density of c {F (x, y) −F _min } / (F _max −F _min ) according to the predetermined position (x, y).

  Moreover, in order to solve the said subject, the 3rd form of this invention is a surface which arrange | positions the transmittance | permeability adjustment body on the light emission surface of a light-guide plate by the arrangement | positioning method of the transmittance | permeability adjustment body in any one of said. The manufacturing method of a state lighting apparatus is provided.

According to the first aspect of the present invention, by arranging the transmittance adjusting body that constitutes the transmittance adjusting member with a pattern density that satisfies the above formula, the luminance unevenness and the angle dependent unevenness are reduced without reducing the luminance. Can be emitted from the light exit surface.
Furthermore, the transmittance adjusting body and the light guide plate can be prevented from shifting by arranging the transmittance adjusting body directly on the light exit surface of the light guide plate. Thereby, even when the planar illumination device is arranged in a direction in which the light exit surface is parallel to the vertical direction, a direction in which the light exit surface is in the downward direction in the vertical direction, etc., the transmittance adjusting body is displaced from the predetermined position of the light guide plate. Can be prevented.

Moreover, according to the 2nd form of this invention, the density pattern of the transmittance | permeability adjustment body can be easily calculated, determined, and arrange | positioned. Thereby, the transmittance adjusting body can be easily disposed at a position where luminance unevenness and angle-dependent unevenness on the light exit surface of the light guide plate can be reduced.
Moreover, according to the 3rd form of this invention, the planar illuminating device which inject | emits the light by which the brightness nonuniformity and the angle dependence nonuniformity were reduced can be produced easily.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a planar lighting device, a method of arranging a transmittance adjusting body, and a manufacturing method of a planar lighting device according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

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 emitting 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, 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. 7) 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, and basically, as shown in FIGS. 3, 4 and 5A, A plurality of linear light sources 12 and a rectangular light exit surface 22a are formed on the side of the light exit surface 14a, and a plurality of parallel grooves 22b for accommodating the plurality of linear light sources 12 are formed on the back side thereof. The 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 grooves 22b, and the light exit surface 14a having a rectangular shape is disposed on the light exit surface 22a side of the light guide plate 22. And an optical member unit 24 having a rectangular plane, and a reflecting member 26 disposed along the rear surface 22d of the light guide plate 22.
4 shows only the unit light guide plate 23 having one parallel groove 22b which is one unit constituting the light guide plate 22, but as shown in FIG. The illuminating device main body 14 is constituted by a light guide plate 22 including 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 emitting surface 22 a of the light guide plate 22. Needless to say, it has a 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 cold cathode tube (CCFL: see FIG. 7) that is linear, that is, a thin rod, 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 tube (CCFL), for example, a normal fluorescent tube, a hot cathode 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 An LED light source may be used in which an LED is disposed on the bottom surface, LED light is incident from the top and bottom surfaces of the light guide, and is emitted from the side surface of the light guide.
The inverter unit 18 and the power source 38 (see FIG. 7) for turning on and off the plurality of linear light sources 12 will be described later.

The light guide plate 22 includes a plurality of unit light guide plates 23 as shown in FIG.
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. .
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 groove 22b may have a hyperbola shape as in the illustrated example, but may be any shape as long as it has a luminance uniforming effect such as a triangular shape, a U shape, and a parabolic shape. Those disclosed in [0040] to [0058] of Japanese Patent Application Laid-Open No. 2005-23497 related to the applicant's application 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 emitting 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 can increase the uniformity of the luminance of the illumination light emitted from the individual light emission surface 23a, and the decrease in luminance should be small. For example, the shape disclosed in Japanese Patent Application No. 2004-325251 relating to the application of the present applicant can also be applied.

The unit light guide plate 23 allows illumination light emitted from the linear light source 12 stored in the parallel groove 22b to enter, and is inclined in a direction parallel to the individual light exit 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 of the light guide plate 22. In this case, it goes without saying that the light emitting surfaces 23a of the plurality of unit light guide plates 23 are connected to one another, and the light guide plate 22 forms a uniform light emitting surface 22a.

  As shown in FIG. 5A, the light guide plate 22 may be a single light guide plate connector integrally formed with a plurality of unit light guide plates 23 connected, but cost reduction and yield are achieved. In consideration of the improvement of the above and the ease of manufacture, a plurality of integrally formed light guide plate assemblies of unit light guide plates 23 may be connected to form a large-sized light guide plate having a large area light output surface 22a. In this case, the light guide plate connector is connected to the thin end portions 23c of the unit light guide plates 23 of the adjacent light guide plate connectors, and is connected in a direction orthogonal to the parallel grooves 22b to increase the size and the light exit surface. 22a may be increased in area, or the end portions orthogonal to the thin-walled end portion 23c of the adjacent light guide plate connector are connected to each other and connected in a direction parallel to the parallel groove 22b to increase the size of the light output surface 22a. The area may be increased, or these may be performed simultaneously and connected in a direction parallel to and perpendicular to the parallel grooves 22b, so that the area of the light exit surface 22a may be increased. At this time, it is needless to say that the uniform planar light emitting surfaces of the plurality of light guide plate connectors are connected to each other, and the light guide plate 22 forms a uniform planar light emitting surface 22a. Absent. 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 to which the light guide plate connector is connected, and is disposed above the light guide plate 22. The optical member unit 24 to be described later preferably has substantially the same size (area) as the light exit surface 22a of the light guide plate 22.

The transmittance adjusting member 25 is used to reduce luminance unevenness of illumination light emitted from the light exit surface 22 a of the light guide plate 22, and includes a large number of transmittance adjusting bodies 27.
6A is a top view showing a schematic configuration of the transmittance adjusting member 25, and FIG. 6B is an enlarged view of a part of the transmittance adjusting member 25 shown in FIG. 6A. FIG. Here, in FIG. 6A, one pitch is the length from one end of the unit light guide plate 23 in the direction perpendicular to the parallel grooves.
As shown in FIGS. 6A and 6B, a large number of transmittance adjusting bodies 27 constituting the transmittance adjusting member 25 are dots of various sizes having a predetermined transmittance, and have a rectangular shape. However, they are arranged directly on the light exit surface 22a in a predetermined pattern, for example, a pattern (halftone dot pattern) in which the dot size and the number of dots arranged differ depending on the position. Moreover, the hole part 28 is formed by arrange | positioning many transmittance | permeability adjustment bodies 25. FIG.
As the transmittance adjusting body 27, a diffuse reflector can be used.
Examples of the diffuse reflector include those obtained by coating pigments such as silica, titanium oxide, and zinc oxide that scatter light, or beads such as resin, glass, and zirconia together with a binder. In addition, it is a material with high reflectance and low light absorption. For example, metals such as Ag and Al can be used.
The arrangement pattern of the transmittance adjusting body 27 will be described in detail later.

  The optical member unit 24 is for making the uniform illumination light emitted from the transmittance adjusting member 25 more uniform and emitting the illumination light with further improved uniformity from the light exit surface 14a of the illumination device body 14. 3 and FIG. 4, a microprism array parallel to the parallel grooves 22b of the light guide plate 22 constituting the light emitting surface 14a is formed, and the illumination light emitted from the transmittance adjusting member 25 is condensed. A prism sheet 24a for improving the brightness and improving the luminance, and a diffusion sheet 24b for diffusing and uniformizing the illumination light emitted from the transmittance adjusting member 25.

The arrangement order and the number of the arrangement of the prism sheets 24a and the diffusion sheets 24b are not limited, and the prism sheets 24a and the diffusion sheets used in the optical member unit 24 can be made uniform. Any optical member may be used as long as the illumination light emitted from the transmittance adjusting member 25 is more limited. 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.
Regarding the optical members used in the optical member unit 24 including the prism sheet 24a and the diffusion sheet 24b, those disclosed in [0028] to [0033] of Japanese Patent Application Laid-Open No. 2005-23497 related to the application of the present applicant. 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 main body 14 is housed and supported from above, and the lower housing 30 that covers the four side surfaces thereof, and the opening 16a on the upper surface that is smaller than the rectangular light emitting surface 14a of the lighting device main body 14 are provided. A rectangular opening is formed, the lower surface is opened, and the upper housing 32 is covered from above so as to cover the light guide plate assembly 14 and the lower housing 30 in which the light guide plate assembly 14 is housed, including its four side surfaces. A concave (U-shaped) folding member 34 fitted between the side wall of the lower housing 30 and the side wall of the upper housing 32, and the rear surface 22 d of the light guide plate 22. Is supported by the reflecting member 26, and the lighting device is And a light guide plate supporting member 36 which also supports the entire body 14. 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 member 34 needs to be disposed in each gap between the inner wall surface of the upper casing 32 and the upper casing 32 opposed to the lower casing 30 on the four side surfaces of the casing 16. It may be arranged between the side wall of the upper housing 32 and the side wall of the upper housing 32. Moreover, it is preferable to 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.

Furthermore, as the light guide plate support, a member obtained by inverting the light guide plate can be used.
By using a member obtained by inverting the light guide plate for the light guide plate support, positioning of the light guide plate and the light guide plate support can be facilitated, and the light guide plate support needs to be manufactured as a separate member. The manufacturing cost can be reduced.
Furthermore, by using a defective product that cannot be used as a light guide plate due to scratches on the surface, etc., the manufactured parts can be used efficiently, improving the yield of the product, and manufacturing costs. Can also be lowered.

Note that the housing 16 is provided with a fastener such as an L-shaped metal fitting that joins the four corners, or between the prism sheet 24a of the planar device main body 14 and the peripheral portion of the opening 16a of the upper housing 30. An elastic member made of an elastic material such as rubber or a protective member for protecting the entire upper surface of the prism sheet 24a of the planar apparatus main body 14 may be provided.
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 planar device body 14 will be described.
The drive device 37 shown in FIGS. 7A and 7B 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 illumination 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. 7B 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. In the periphery of the opening 16a of the casing 16 on the side orthogonal to the linear light source 12, as in the planar illumination device 11 shown in FIG. 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.

Here, an arrangement pattern of a large number of transmittance adjusting bodies 27 constituting the transmittance adjusting member 25 will be described in detail.
The transmittance adjusting body 27 is arranged with a constant distribution so that the pattern density does not change in the direction parallel to the axis of the light source 12, and is arranged with a predetermined pattern density distribution in the direction perpendicular to the axis of the light source 12. . The pattern density distribution in the direction perpendicular to the axis of the light source 12 is determined by the method described below.

First, an arbitrary position (x, y) of the light emitting surface of the planar illumination device when the transmittance adjusting member 25 having the bias density ρb is used on the entire surface of the light emitting surface of the light guide plate. ) Is assumed to be F (x, y). In addition, the relative luminance of light emitted from the light emitting surface of the planar illumination device when the transmittance adjusting member having the bias density ρb is the transmittance adjusting member 25 disposed on the entire light emitting surface of the light guide plate. Is the maximum value, that is, the maximum luminance is F _max, and the minimum value of the relative luminance, that is, the minimum luminance is F _min . The reference value of relative luminance is an arbitrary value.
At this time, if the pattern density at an arbitrary position (x, y) of the transmittance adjusting body 27 is ρ (x, y), the pattern density ρ (x, y) of the transmittance adjusting body 27 and the relative luminance F (x , Y) satisfies the following formula 1.
ρ (x, y) = c {F (x, y) −F _min } / (F _max −F _min ) + ρb Equation 1
Here, c is the maximum density, 0 <c ≦ 0.3, ρb is the bias density, and 0.5 ≦ ρb.

In the present invention, the pattern density ρ (x, y) is an occupancy rate per unit area (1 mm ² ) of the transmittance adjusting body 27 existing at an arbitrary position (x, y), and ρ (x, y ) = 1, the transmittance adjusting body 27 is arranged on the entire surface within the unit area, and when ρ (x, y) = 0, it is not arranged at all within the unit area.
Further, when the pattern density ρ (x, y) exceeds 1, that is, when the pattern density exceeds 100%, the transmittance adjusting body is arranged in a double layer (two layers). That is, the transmittance adjusting body is disposed on the entire surface within the unit area, and the transmittance adjusting body having a pattern density of (ρ (x, y) −1) is disposed. Here, the transmittance adjusting body has a uniform thickness, and the thickness of the transmittance adjusting body is doubled in the portion where the transmittance adjusting body is arranged in a double layer.

  By arranging the transmittance adjusting body 27 directly on the light exit surface 22a of the light guide plate 22 as in this embodiment, for example, the planar illumination device 10 is disposed so that the light exit surface 14a is parallel to the vertical direction. In this case, even when the light emission surface 14a is arranged downward in the vertical direction, it is possible to prevent a positional shift between the light emission surface 22a and the arrangement pattern of the transmittance adjusting body 27.

  Further, when the transmittance adjusting body 27 of the transmittance adjusting member 25 is arranged so as to satisfy the pattern density ρ (x, y) of the above formula 1, the transmittance adjusting body 27 is directly arranged on the light exit surface 22a. However, it is possible to suppress a decrease in average luminance of light emitted from the light emitting surface 14a of the planar illumination device 10 and reduce luminance unevenness.

Further, in the above formula 1, ρb is set to 0.5 or more, and the transmittance adjusting body 25 having a certain density or more is disposed on the entire light exit surface 22 a of the light guide plate 22, thereby generating the pattern density of the transmittance adjusting body 25. It is possible to prevent the occurrence of uneven angle dependency.
Here, the angle-dependent unevenness is observed when the luminance distribution changes depending on the angle at which the light exit surface is observed, for example, when viewed from a direction perpendicular to the light exit surface and when viewed from a direction inclined by 45 °. Depending on the angle, this means uneven brightness.
That is, by setting ρb to 0.5 or more, it is possible to prevent the luminance distribution (brightness unevenness) of light emitted from the light exit surface of the light guide plate from changing depending on the angle at which the light exit surface of the light guide plate is viewed.
Further, by determining the pattern density according to the relative brightness F (x, y) using the above formula 1, brightness unevenness can be reduced while maintaining high brightness.
In addition, by setting the range of c to 0.3 or less, even when the transmittance adjusting body is arranged directly on the light exit surface, the luminance unevenness can be suitably reduced.

  As described above, by arranging the transmittance adjusting body 27 of the transmittance adjusting member 25 so as to satisfy the pattern density ρ (x, y) of the above formula 1, the direction perpendicular to the light exit surface is also inclined. In addition, uneven brightness can be reduced and light with high brightness can be emitted.

  In this way, if the luminance unevenness is reduced by using the transmittance adjusting member 25, it is not necessary to sufficiently diffuse the light by the diffusion film 14, so that the diffusion film 14 can be made thinner. Further, the use of the prism sheet can be stopped, or the number of prism sheets used can be reduced, and a lighter and cheaper backlight unit can be provided.

Here, the transmittance adjusting body 27 preferably has a pattern density ρ (x, y) = 1, that is, the transmittance when the transmittance adjusting body is disposed on the entire surface is 10% or more and 50% or less, 20% More preferably, it is 40% or less.
By setting the transmittance to 10% or more, luminance unevenness can be suitably reduced, and by setting the transmittance to 50% or less, luminance unevenness can be reduced without reducing the average luminance.
Furthermore, the said effect can be acquired more suitably by making the transmittance | permeability into 20% or more and 40% or less.

  Moreover, it is preferable that the transmittance | permeability adjustment body 27 shall be 0.1 mm or less in the width | variety of one transmittance | permeability adjustment body. By setting the width to 0.1 mm or less, the dimensions are less than the discriminating ability of the naked eye, and when actually used as a liquid crystal display device, the shape of the transmittance adjusting body 27 is projected onto the light exit surface of the planar illumination device. Luminance unevenness is suppressed, and luminance unevenness can be efficiently reduced.

The bias density ρb is preferably ρb ≦ 1.5.
By setting ρb to 1.5 or less, the pattern density ρ (x, y) becomes 2.0 or less, and the transmittance adjusting body can be arranged in a double or less. That is, it is possible to arrange a transmittance adjusting body having a pattern density that satisfies the above formula 1 without triplet the transmittance adjusting body.
By arrange | positioning the transmittance | permeability adjustment body by double or less, it can arrange | position easily on the light emission surface of a light-guide plate, and can reduce apparatus cost and manufacturing cost.
Further, by setting ρb to 1.5 or less and ρ (x, y) to 2.0 or less, luminance unevenness can be reduced while preventing a decrease in average luminance.

In this embodiment, the pattern density distribution is adjusted by changing the size of the transmittance adjusting body. However, the present invention is not limited to this, and the arrangement interval of the transmittance adjusting bodies having a fixed shape is adjusted. By doing so, the pattern density can also be adjusted. For example, various methods such as an FM screening method and an AM core method can be used as a method for arranging the transmittance adjusting body according to the pattern density.
Here, the transmittance adjusting body is preferably arranged by the FM screening method. Thereby, the transmittance adjusting body can be dispersed and arranged as fine and uniform dots, and the arrangement pattern of the transmittance adjusting body can be made difficult to visually recognize from the light exit surface of the backlight unit. That is, the arrangement pattern of the transmittance adjusting body is projected from the light exit surface of the backlight unit, and uneven light can be prevented from being emitted, and more uniform light can be emitted. In addition, it is possible to prevent the dot size from becoming too small to make it difficult to form the transmittance adjusting body.

Here, the transmittance adjusting body has a maximum dimension of 500 μm or less. For example, in the case of a rectangular shape, the length of one side is preferably 500 μm or less, and in the case of an elliptical shape, the major axis is preferably 500 μm or less, and 200 μm or less. It is more preferable. By setting the maximum dimension of the transmittance adjusting body to 500 μm or less, the shape of the transmittance adjusting body becomes difficult to see, and by setting the maximum dimension to 200 μm or less, the shape of the transmittance adjusting body becomes invisible. When used as a liquid crystal display device, the shape of the transmittance adjusting body is not projected onto the light exit surface of the backlight unit, resulting in uneven brightness, and the uneven brightness can be reduced efficiently.
Further, it is more preferable that the transmittance adjusting body has a maximum dimension of 100 μm or less. By making the maximum dimension 100 μm or less, the dimension can be more surely below the discrimination ability of the naked eye. When actually used as a liquid crystal display device, the shape of the transmittance adjusting body is the light emission of the backlight unit. Luminance unevenness can be reduced more reliably and efficiently without being unevenly projected onto a surface.

Moreover, as a method of printing the transmittance adjusting body on the surface of the light guide plate, various printing methods such as screen printing, offset printing, and gravure printing can be used.
In this way, by making the transmittance adjusting body a fixed shape and adjusting the pattern density with the arrangement interval, the transmittance adjusting body is prevented from being projected too much on the light exit surface of the backlight unit, and the dot size is reduced. It is also possible to prevent the formation of the transmittance adjusting body from becoming too small.

Here, such a planar lighting device adjusts the transmittance by arranging the transmittance adjusting body on the light exit surface of the light guide plate based on the arrangement pattern determined by the above-described method using Equation 1 above. A member is provided, an optical member is disposed on the surface, and the other light source 12, casing 16, inverter unit 18 and the like are disposed at predetermined positions.
Further, the transmittance adjusting body is arranged with a transmittance adjusting body corresponding to the bias density ρb, and then the transmittance adjusting corresponding to c {F (x, y) −F _min } / (F _max −F _min ). The transmittance adjusting body satisfying the above formula 1, that is, the transmittance adjusting body corresponding to c {F (x, y) −F _min } / (F _max −F _min ) + ρb is preferably used. You may arrange at once.

Further, by determining the arrangement of the transmittance adjusting body using the above formula, the arrangement pattern of the transmittance adjusting body can be more easily determined. As a result, it is not necessary to repeat trial manufacture in order to determine a suitable arrangement pattern of the transmittance adjusting body, the design cost can be reduced, the time spent for the design can be shortened, and as a result, the transmittance adjusting member can be efficiently obtained. Can be designed.
Further, by using the above arrangement method, a transmittance adjusting body is arranged on the surface of the light guide plate to manufacture a planar lighting device, thereby emitting high-luminance light with reduced luminance unevenness and angle-dependent unevenness. A planar illumination device can be easily and efficiently produced.

Hereinafter, the surface illumination device of the present invention will be described in more detail with specific examples.
The planar illumination device of the present embodiment has the same configuration as the planar illumination device shown in FIGS.
In the present embodiment, a cold cathode tube having a diameter of 2.6 mm is used as the light source 12, and the light guide plate 23 has the thickness of the unit light guide plate 23 from the center of the unit light guide plate 22 as shown in FIG. 5B. The thin noodles, that is, the distance L to the joint surface with the adjacent unit light guide plate 23 is 14 mm, the thickness D of the thickest portion 23b of the unit light guide plate 23 is 5.5 mm, and the parallel grooves 22b The distance d1 between the front end portion of the light source and the light exit surface is 1 mm, the width G1 of the end of the parallel groove 22b opposite to the light exit surface 23a is 5.5 mm, and the junction between the inclined rear surface and the adjacent unit light guide plate The light guide plate is formed by connecting ten unit light guide plates having a smooth curved surface shape, a radius of curvature R of 15 mm, an inclination θ of the inclined back surface of 15.76 °, and a parallel groove 22b having a hyperbolic shape. It was used. The light exit surface 22 a of the light guide plate 22 has a rectangular shape with a length in the direction parallel to the light source 12 of 500 mm and a length in the direction perpendicular to the light source 12 of 280 mm.

  First, the transmittance adjusting body is fixed on the entire surface of the light emitting surface, that is, from the light emitting surface of the illumination device main body of the planar lighting device having the transmittance adjusting member in which only the bias density ρb in the above formula 1 is arranged. A visual test of the emitted light was performed. Here, a planar illumination device was produced in which the bias density ρb of the transmittance adjusting body was 0, 0.3, 0.5, 0.8, and 1.0, respectively.

The visual test is performed by 10 observers from a point 50 cm away from the light exit surface of the light guide plate from a direction perpendicular to the light exit surface, that is, the front direction, and a direction inclined by 45 ° with respect to the perpendicular direction. The exit surface was observed to determine whether or not there was a difference in brightness unevenness, that is, whether or not there was angle-dependent unevenness.
As a result of the judgment by the observer, if the number of persons judged that a difference in luminance unevenness was felt between the front direction and the direction inclined by 45 ° is x or more if the number is 6 or more and Δ or 2 if the number is 3 or more and 5 or less. If it was less than one name, it was rated as ○.

  Table 1 below shows the results of a visual test performed on the planar illumination device in which the bias density ρb of the transmittance adjusting body was 0, 0.3, 0.5, 0.8, and 1.0, respectively.

Thus, by setting the bias density ρb to 0.5 or more, angle-dependent unevenness can be reduced, and by setting the bias density ρb to 0.8 or more, angle-dependent unevenness can be more reliably reduced.
From the above, it is clear that the bias density ρb is preferably 0.5 or more, and more preferably 0.8 or more.

Next, in the planar lighting device having such a shape, in order to calculate the pattern density ρ (x, y) of the transmittance adjusting body that satisfies the above formula 1, the pattern density of the transmittance adjusting body depends on the position. A relative illumination F (x, y) of light emitted from the light exit surface of the illumination device body of the planar illumination device was calculated using a planar illumination device in which a constant transmittance adjusting member was arranged.
FIG. 9A is a top view showing a transmittance adjusting member in which a transmittance adjusting body is arranged with ρb = 0.8, and FIG. 9B shows the transmittance adjusting member shown in FIG. FIG.
In this embodiment, as shown in FIGS. 9A and 9B, the transmittance adjusting body 27a is arranged with the pattern density kept constant at ρ (x, y) = ρb = 0.8 (80%). The relative luminance (x, y) was calculated using the transmittance adjusting member 25a in which the hole 28a was formed. In this embodiment, the distance La between the hole 28a and the adjacent hole 28a in the direction parallel to the extending direction of the light source is set to La = Lb = 0.5 mm, and the transmittance adjusting body The arrangement pattern was adjusted.

Here, the relative luminance F (x, y) was calculated as follows.
First, the light emitting surface 14a of the lighting device body 14 of the planar lighting device 10 is fixed to an XY stage, and the luminance meter is fixed so as to be perpendicular to the light emitting surface 14a of the lighting device body 14. Then, the luminance at the position of the light exit surface 14a of the illuminating device main body 14 is measured by a luminance meter to obtain information on the brightness related to the specific position of the light exit surface 22a of the light guide plate 22.
Thereafter, by moving the XY stage, the luminance at each position on the light exit surface 14a of the illuminating device body 14 is measured, and the ratio of the luminance at each position to a predetermined reference value is determined at that position (x, y). The relative luminance was calculated as F (x, y). Further, the maximum luminance of the measured and calculated relative luminance, that is, the maximum value of the relative luminance is F _max , and the minimum luminance, that is, the minimum value of the relative luminance is F _min . The measurement results thus measured are shown in FIG. Here, in the graph of FIG. 10, the vertical axis is the relative luminance, and the horizontal axis is the distance from the center of the light guide plate (the center of the parallel groove). For reference, the result of calculating the relative luminance of light emitted from the light emission surface of the planar illumination device having the same configuration and shape except that the transmittance adjusting body is not provided is also shown. Here, in the present embodiment, the relative luminance is normalized by assuming that the average luminance in a state where the transmittance adjusting member is not installed is 1.

Next, the pattern density ρ (x, y) corresponding to the relative luminance F (x, y) is calculated from the measurement result using Equation 1 above. Here, in this embodiment, when the maximum density c is set to c = 0.1, 0.2, 0.3, 0.5, and 0.8, the pattern densities ρ (x, The distribution of y) was calculated.
FIG. 11 shows the distribution of the pattern density ρ (x, y) of the transmittance adjusting body calculated as c = 0.1, 0.2, 0.3, 0.5, and 0.8, respectively. In the graph of FIG. 11, the vertical axis is the pattern density ρ (x, y), and the horizontal axis is the distance [mm] from the center of the light guide plate (the center of the parallel groove).

Based on the pattern density ρ (x, y) of the transmittance adjusting body of c = 0.1, 0.2, 0.3, 0.5, 0.8 calculated in this way, the transmittance adjusting body is Each of the arranged planar lighting devices was created. Here, in FIGS. 6A and 6B described above, the transmittance in which the transmittance adjusting body 27 is arranged based on the result of calculating the distribution of the pattern density ρ (x, y) with c = 0.1. This is the adjustment member 25.
Here, in the present embodiment, the distribution of the pattern density ρ (x, y) is calculated every 0.5 mm in the width direction (lateral direction in FIG. 6), and the calculated pattern density ρ (x, y) is calculated. In order to satisfy, the transmittance adjusting body 27 was arranged by adjusting the area of the hole 28 when 0.5 ≦ ρ, and adjusting the area of the transmittance adjusting body 25 when ρ <0.5. In this embodiment, the arrangement pattern of the transmittance adjusting body is set such that the distance La between the hole portion and the adjacent hole portion in the direction parallel to the light source extending direction Lb is La = Lb = 0.5 mm. Adjusted.
In this embodiment, the transmittance adjusting member 27 is manufactured by arranging the transmittance adjusting member 27 so that the hole 28 or the transmittance adjusting member 25 has a substantially square shape.
Here, in the present embodiment, when the transmittance adjusting body is disposed on the entire surface, that is, when the pattern density ρ (x, y) is 1, the transmission created by the white ink having a transmittance of 33% at a wavelength of 550 nm. A rate adjuster 27 was placed.

  The relative luminance of light emitted from the light exit surface of the illumination device main body of the planar illumination device having the transmittance adjusting member 25 thus created was measured. The measurement method was the same as the measurement method for measuring the relative luminance F (x, y) described above. The measurement results are shown in FIG. Here, in the graph of FIG. 12, the vertical axis is the relative luminance, and the horizontal axis is the distance from the center of the light guide plate (the center of the parallel groove). For comparison, the relative luminance of the light emitted from the light exit surface of the illumination device body of the planar illumination device having the same configuration except that the transmittance adjustment member is not provided, and the pattern density of the transmittance adjuster The measurement result of measuring the relative luminance of the light emitted from the light exit surface of the illumination device body of the planar illumination device in which ρ (x, y) is 0.8 and a constant transmittance adjusting member is arranged is also shown.

As shown in FIG. 12, the luminance unevenness can be reduced by arranging the transmittance adjusting body with a pattern density satisfying Expression 1. Further, since the transmittance adjusting body having a constant density as the bias density is disposed as described above, it is possible to prevent the occurrence of angle-dependent unevenness.
That is, by arranging the transmittance adjusting body with a pattern density satisfying Equation 1, it is possible to reduce luminance unevenness and angle-dependent unevenness.

Next, other specific examples will be described together with other arrangement patterns of the transmittance adjusting member shown in FIGS. 13A and 13B and the graphs of FIGS.
In this embodiment, the other conditions are the same as those in the above-described specific embodiment except that the bias density ρb of the transmittance adjusting body is set to 1.0. FIG. 13A is a top view showing a transmittance adjusting member in which a transmittance adjusting body is arranged with a constant pattern density of 1.0 and FIG. 13B shows c = 0.14. It is a top view which shows the transmittance | permeability adjustment member except the bias density part of the transmittance | permeability adjustment member which has arrange | positioned the transmittance | permeability adjustment body with the calculated pattern density.
In this embodiment, first, in order to calculate the pattern density ρ (x, y) of the transmittance adjusting body that satisfies the above formula 1, the pattern density is 1.0 as shown in FIG. Using a planar illumination device in which a constant transmittance adjustment body 27b is disposed on the entire surface, the relative luminance F (x, y) of light emitted from the light exit surface of the illumination device main body of this planar illumination device was calculated.
The relative luminance F (x, y) was measured by the same method as in the specific example.
The calculated relative luminance is shown in FIG. Here, in the graph of FIG. 14, the vertical axis is the relative luminance, and the horizontal axis is the distance from the center of the light guide plate (the center of the parallel groove). For reference, the result of calculating the relative luminance of light emitted from the light emission surface of the planar illumination device having the same configuration and shape except that the transmittance adjusting member is not provided is also shown. Here, also in the present embodiment, the relative luminance is normalized by setting the average luminance in a state where the transmittance adjusting member is not installed to 1.

Next, the pattern density ρ (x, y) of the transmittance adjusting body that satisfies the above formula 1 was calculated based on the calculated relative luminance F (x, y) shown in FIG. Here, in this example, the maximum density c was calculated for c = 0.09, 0.14, 0.18, 0.3, 0.5, 0.8.
FIG. 15 shows the distribution of the pattern density ρ (x, y) of the transmittance adjusting body calculated as c = 0.09, 0.14, 0.18, 0.3, 0.5, 0.8. . In the graph of FIG. 15, the vertical axis is the pattern density ρ (x, y), and the horizontal axis is the distance [mm] from the center of the light guide plate (the center of the parallel groove).

Based on the pattern density ρ (x, y) of the transmittance adjusting body of c = 0.09, 0.14, 0.18, 0.3, 0.5, 0.8 calculated in this way. A planar lighting device in which a rate adjusting body was arranged was created.
As an example, a transmittance adjusting member that satisfies the above formula (1) when c = 0.14 and ρb = 1.0 has a transmittance adjusting body 27b disposed on the entire surface shown in FIG. The transmittance adjusting body 27c having the distribution shown in FIG.
The relative luminance of the light emitted from the light exit surface of the illumination device main body of the planar illumination device having the manufactured transmittance adjusting member 25 was measured. The measurement method was the same as the measurement method for measuring the relative luminance F (x, y) described above. The measurement results are shown in FIG. Here, in the graph of FIG. 16, the vertical axis is the relative luminance, and the horizontal axis is the distance from the center of the light guide plate (the center of the parallel groove). For comparison, the relative luminance of the light emitted from the light exit surface of the illumination device body of the planar illumination device having the same configuration except that the transmittance adjustment member is not provided, and the pattern density of the transmittance adjuster The measurement result of measuring the relative luminance of the light emitted from the light exit surface of the illumination device body of the planar illumination device in which ρ (x, y) is 0.8 and a constant transmittance adjusting member is arranged is also shown.

As shown in FIG. 16, even when the bias density ρb is set to ρb = 1, the luminance unevenness can be reduced by arranging the transmittance adjusting body with the pattern density satisfying the above formula 1.
It can also be seen that by setting c to 0.3 or less, the light emitted from the light exit surface can be made more uniform and without uneven brightness.
From the above, the effects of the present invention are clear.

Next, an example of a lighting device using the planar lighting device of the present invention will be described.
FIG. 17: is a schematic sectional drawing which shows one Embodiment which used the planar illuminating device of this invention for room illumination.
The planar illumination device 100 is an inverted Fuji-shaped illumination device in which two illumination device bodies are inclined at a predetermined angle, and includes a plurality of linear light sources 12, two illumination device bodies 14, and two housings. It has a body 16, two inverter units 18, a power source 38, and a fixing member 102.

  The fixing member 102 has a substantially isosceles trapezoidal shape with a cross section in a direction perpendicular to the bottom surface 102a passing through the center of the bottom surface 102a and having a line perpendicular to the bottom surface 102a as an axis of symmetry, and the bottom surface 102a is fixed to the ceiling. . That is, the fixing member 102 has inclined surfaces 102b and 102c that are inclined at a predetermined angle with respect to the ceiling 102a. Further, the inside of the fixing member 102 is hollow.

One lighting device main body 14 is housed in a housing 16, and the housing 16 is fixed to the inclined surface 102b. Further, the inverter unit 18 is fixed to a surface opposite to the surface on which the housing 16 of the inclined surface 102b is disposed. That is, the housing 16 is fixed to the outer surface of the inclined surface 102b, and the inverter unit 18 is fixed to the inner surface of the inclined surface 102b.
The other lighting device main body 14 and the housing 16 are disposed on the outer surface of the inclined surface 102c in the same manner as the lighting device main body 14 and the housing 16 disposed on the inclined surface 102b.
That is, the two illuminating device main bodies 14 and the two housings 16 are arranged symmetrically with respect to a line passing through the center of the bottom surface 102a and perpendicular to the bottom surface 102a.

  The power source 38 is fixed to a surface on the opposite side of the surface of the fixed portion 102 that is in contact with the ceiling, that is, an inner surface of the bottom surface. The power source 38 is connected to a plurality of inverter units and supplies a direct current.

Next, FIG. 18A is a cross-sectional view in a direction parallel to the axis of the linear light source 16 around the illumination device main body 14 of the planar illumination device 100 shown in FIG. 17, and FIG. 14 is a front view of FIG. In FIG. 18A, the casing 16, the transmittance adjusting member 25, and the reflecting member 26 are not shown.
The linear light source 12 includes a plurality of cold cathode tubes 104 arranged in series in parallel grooves of the unit light guide plate. The cold-cathode tube 104 has a U-shape with folded portions at both ends.
The inverter unit 18 includes a plurality of inverters 108, and each inverter 108 is connected to the cold cathode tube 104.

By forming the cold cathode tube 104 in a U shape, only a portion that emits uniform light excluding a portion that does not emit light such as an electrode portion at the end of the cold cathode tube and a portion that emits unstable light is provided on the light guide plate. Can be arranged in parallel grooves.
As a result, it is possible to prevent the occurrence of luminance unevenness at the connection part of the cold cathode tubes 104 arranged in series, and uniform light can be emitted from the linear light source 104.
Cold cathode tubes are limited in the length that can be manufactured according to the diameter due to problems such as strength, but in this way, by using a plurality of cold cathode tubes arranged in series, a cold cathode tube with a small diameter is used. Also, the linear light source can be lengthened. Thereby, it is possible to make the illuminating device main body long in the extending direction of the parallel grooves, that is, the light emitting surface is long and narrow, while preventing the cold cathode tube from being damaged.

  In this way, the planar illumination device 100 in which the two illumination device main bodies 14 whose light emission surfaces are elongated in the extending direction of the parallel grooves are arranged on the inclined surfaces 102b and 102c of the fixed part 102 having the isosceles trapezoidal shape, respectively. It can be used as room lighting in the same manner as an inverted Fuji type lighting device using a hot cathode tube (HCFL).

In addition, by using a cold cathode tube having a long life as a light source, the number of light source replacements can be reduced as compared with a lighting device using a hot cathode tube. Thereby, the cost (labor cost, parts cost) concerning replacement of the light source can be reduced.
Further, by using a cold cathode tube having a smaller amount of mercury and lead than the hot cathode tube as a light source, it is possible to prevent the diffusion of dangerous substances.

  In addition, when arranging a plurality of cold cathode tubes in series, it is possible to prevent uneven brightness at the connecting portion between the cold cathode tubes, so use a U-shaped cold cathode tube as in this embodiment. However, a linear cold cathode tube without a folded portion may be used.

  Further, the present invention is not limited to the reverse Fuji type lighting device, and it can also be used as an embedded lighting device in which a planar lighting device is embedded in a wall or ceiling so that the light emission surface is flush with the wall.

Next, FIG. 19A is a schematic cross-sectional view showing an embodiment in which the planar illumination device of the present invention is used as a signboard, and FIG. 19B is a front view of the planar illumination device. ) Is a side view of the planar illumination device.
The planar illumination device 120 includes a plurality of illumination units 122 and an outer frame body 124.

The illumination unit 122 includes a plurality of linear light sources 12, one illumination device body 14, and one inverter unit 18. Since the illumination unit 122 has the same configuration as the illumination device main body 14 and its peripheral portion shown in FIG. 18 described above, detailed description thereof will be omitted.
The plurality of illumination units 122 are arranged in a two-dimensional direction and spaced apart from each other by a predetermined distance so that the light exit surfaces are on the same plane.

The outer frame body 124 is disposed on the outer periphery of the illumination unit 122, and fixes the illumination unit 122 by a fixing means (not shown). The light emitted from the illumination unit 122 is transmitted through the surface of the outer frame body 124 that faces the light emission surface of the illumination unit 122 (light emission surface of the illumination device main body).
An image is formed on the surface through which the light of the outer frame body 124 of the planar illumination device 120 is transmitted, and the light is emitted from the illumination unit 122 to be used as an illumination signboard for displaying an advertisement or the like. Can do.

  Moreover, in this embodiment, although the illumination unit 122 was arrange | positioned spaced apart by predetermined spacing, you may arrange | position an illumination unit without a clearance gap.

  Although the planar lighting device of the present invention has been described in detail above, the present invention is not limited to the above-described embodiments, and various improvements and modifications may be made without departing from the gist of the present invention. Of course.

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 a top view which shows schematic structure of the transmittance | permeability adjustment member of the planar illuminating device shown in FIG. 3, (b) expanded a part of the transmittance | permeability adjustment member shown to (a). It is an enlarged top view. (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 top view which shows the transmittance | permeability adjustment member which made (rho) b = 0.8, (b) is an enlarged top view which expanded a part of the transmittance | permeability adjustment member shown to (a). It is a graph which shows an example of the result of having measured the relative luminance of the light inject | emitted from the light emission surface of a planar illuminating device. It is a graph which shows distribution of the pattern density of the transmittance | permeability adjustment body which computed the maximum density c as various values based on the calculation result of the relative luminance shown in FIG. It is a graph which shows the result of having calculated the relative luminance of the light inject | emitted from the light emission surface of the planar illuminating device which has arrange | positioned the transmittance | permeability adjustment body of the pattern density shown in FIG. (A) is a top view which shows the transmittance | permeability adjustment member which has arrange | positioned the transmittance | permeability adjustment body to the whole surface constant with pattern density set to 1.0, (b) is transmissive | permeated by the pattern density calculated as c = 0.14. It is a top view which shows the transmittance | permeability adjustment member except the bias density part of the transmittance | permeability adjustment member which has arrange | positioned the rate adjustment body. It is a graph which shows another example of the result of having measured the relative luminance of the light inject | emitted from the light emission surface of a planar illuminating device. It is a graph which shows distribution of the pattern density of the transmittance | permeability adjustment body which computed the maximum density c as various values based on the calculation result of the relative luminance shown in FIG. It is a graph which shows the result of having measured the relative luminance of the light inject | emitted from the light emission surface of the planar illuminating device which has arrange | positioned the transmittance | permeability adjustment body of the pattern density shown in FIG. It is a schematic sectional drawing which shows specific embodiment of the planar illuminating device of this invention. (A) is sectional drawing of the direction parallel to the axis | shaft of the light source around one illuminating device main body of the planar illuminating device shown in FIG. 17, (b) is a front view of an illuminating device main body. (A) It is a schematic sectional drawing which shows specific embodiment of the planar illuminating device of this invention, (b) is a front view of a planar illuminating device, (c) is a side surface of a planar illuminating device. FIG. (A) And (b) is a schematic diagram and a graph explaining angle-dependent unevenness, respectively. It is a disassembled perspective view which shows the conventional planar illuminating device.

Explanation of symbols

10, 11, 100, 120 Planar illumination device 12 Linear light source 14 Illumination device body 14a Light exit surface 16 Housing 16a Opening 18 Inverter unit 18a Drive circuit 18b Transformer 18c Tube current detection circuit 18d Voltage controlled oscillation circuit 20 Inverter housing Part 22 Light guide plate 22a Light exit surface 22b Parallel groove 22c Thinnest part 22d Back 23 Unit light guide plate 23a Individual light exit surface 23b Thick part 23c Thin end 23d Inclined surface 23e Inclined back part 24 Optical member unit 24a Prism sheet 24b Diffusion film 25 Transmittance adjusting member 26 Reflecting member 26a Reflecting film 26b Reflector 27 Transmittance adjusting body 28 Hole 30 Lower housing 32 Upper housing 34 Folding member 36 Light guide plate support member 37 Drive device 38 Power supply 102 Fixing member 104 Cold cathode tube 106 Inn Over data 122 lighting units 124 outer frame

Claims (7)

A planar illumination device that emits light from a light exit surface,
A flat light guide plate for emitting light emitted from the light source from the light exit surface;
A transmittance adjusting member that is directly disposed on the light exit surface and diffuses and emits the light emitted from the light exit surface;
The transmittance adjusting body member is composed of a number of transmittance adjusting bodies,
The pattern density at a predetermined position (x, y) of the transmittance adjusting body is ρ (x, y), and the light exit surface of the surface illumination device is predetermined when the transmittance adjusting body having a pattern density of ρb is arranged. When the relative luminance of the light emitted from the position (x, y) is F (x, y), the relationship between the relative luminance F (x, y) and the pattern density ρ (x, y) is as follows. Expression ρ (x, y) = c {F (x, y) −F _min } / (F _max −F _min ) + ρb
(Where c is 0 <c ≦ 0.3 and ρb satisfies 0.5 ≦ ρb, F _max is the maximum luminance of the relative luminance F (x, y), and F _min is (It is the minimum luminance of relative luminance F (x, y))
A planar illumination device characterized by satisfying the above.   Furthermore, the planar illuminating device of Claim 1 with which the optical member is arrange | positioned at the light-projection surface side of the said transmittance | permeability adjustment member.   The planar illumination device according to claim 2, wherein the optical member includes at least one of a diffusion film, a prism sheet, and a diffusion plate.   The planar lighting device according to claim 1, wherein the ρb satisfies ρb ≦ 1.5. A transmittance adjusting member that is disposed on the light emitting surface of the light guide plate of the planar lighting device having at least a flat light guide plate that emits light from the light exit surface, and diffuses and emits the light emitted from the light guide plate. A method for arranging a large number of transmittance adjusting bodies to be configured,
The pattern density of the transmittance adjusting body at a predetermined position (x, y) of the transmittance adjusting member is ρ (x, y),
When the relative luminance of light emitted from a predetermined position (x, y) on the light exit surface of the planar illumination device in which the transmittance adjusting body having a pattern density of ρb is arranged is F (x, y),
The relationship between the relative luminance F (x, y) and the pattern density ρ (x, y) is expressed by the following equation:
ρ (x, y) = c {F (x, y) −F _min } / (F _max −F _min ) + ρb
(In the formula, c satisfies 0 <c ≦ 0.3 and 0.5 ≦ ρb, F _max is the maximum luminance F (x, y) of the relative luminance, and the relative luminance F (x, y) Is the minimum brightness)
The transmittance adjusting body is arranged directly on the light exit surface of the light guide plate so as to satisfy the above. The transmittance adjusting body having a pattern density of ρb is disposed on the entire light exit surface of the light guide plate,
Thereafter, in accordance with a predetermined position (x, y), c { F (x, y) -F min} / (F max -F min) and the transmittance adjusters are pattern density becomes Claim 5 To arrange the transmittance adjusting body.   The manufacturing method of the planar illuminating device which arrange | positions the transmittance | permeability adjustment body on the light emission surface of a light-guide plate by the arrangement | positioning method of the transmittance | permeability adjustment body of Claim 5 or 6.

Images