JP4741407B2 - Planar illumination device and liquid crystal display device using the same - 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 emission surface, and is a planar illumination device that illuminates the interior or exterior, or a liquid crystal display panel, an advertisement panel, an advertisement tower, The present invention relates to a planar illumination device used as a backlight for a signboard or the like and a liquid crystal display device using the same.

In a liquid crystal display device, a planar illumination device is used as a backlight that irradiates light from the back side of the liquid crystal panel and illuminates the liquid crystal panel. Similarly, planar lighting devices are used for billboards on advertising panels and advertising towers.
Such a planar illumination device includes a light source for illumination, a light guide plate that diffuses light emitted from the light source and irradiates an object to be illuminated, a prism sheet that further uniformizes light emitted from the light guide plate, and a diffusion sheet , And components such as an inverter unit, and irradiates uniform light from the light exit surface of the light guide plate.

  FIG. 12 shows an example of a conventional planar illumination device. A planar illumination device 110 shown in FIG. 12 covers a light guide plate 122 that emits light emitted from a linear light source (not shown) from a light output surface, a lower housing 130 that holds the light guide plate 122, and a cover from above. And an inverter unit 118 that is connected to a linear light source and used to light the linear light source. As shown in FIG. 12, in the planar lighting device 110, the inverter unit 118 is disposed on the back surface side that is the surface opposite to the light guide plate 122 of the lower housing 130. When the inverter unit 118 is arranged in this way, it is common to form a through hole or the like in the lower housing 130 and connect the linear light source and the inverter unit through this.

The planar illumination device as shown in FIG. 12 has a problem that the thickness of the entire planar illumination device increases because the inverter unit is disposed on the back side. In addition, a member for providing a space for storing the inverter unit, wiring, and the like is required, and there is a problem that the number of parts increases.
In addition, since a member for providing a space for storing the inverter unit is arranged on the back surface of the housing, this member becomes an obstacle when attaching the planar lighting device to the ceiling or wall surface, and makes the attachment difficult. There was also a problem.

  The present invention has been made in view of the above problems, and can be easily reduced in thickness, and it is not necessary to arrange a new member or the like for housing the inverter unit on the back surface of the casing, and the ceiling or wall surface. It is an object of the present invention to provide a planar lighting device that can be easily attached to the projector and that can suppress an increase in the number of components. Another object of the present invention is to provide a liquid crystal display device using such a planar illumination device.

In order to solve the above problems, a first aspect of the present invention is to turn on a linear light source, a light guide plate that emits light emitted from the linear light source from a planar light emission surface, and the linear light source. A planar lighting device comprising: an inverter unit used to perform the operation; and a housing that is disposed on a surface opposite to the light emitting surface and supports the linear light source and the light guide plate, and a bottom portion of the housing have a recess for placing the inverter unit on one end side of the inverter unit includes a transformer that is disposed in the substrate and the substrate, at least, the transformer does not overlap the light guide plate in the recess The inverter unit is disposed at a position, and further, at least a part of the substrate of the inverter unit is disposed between the rear surface of the light guide plate opposite to the light emitting surface and the housing. There is provided a planar illumination device characterized in that it is arranged on the rear surface and parallel to the light guide plate.

1st aspect of this invention WHEREIN: The said recessed part is extended in the direction orthogonal to the axis line of this linear light source at the one end side of the bottom part of the said housing | casing in the side where the one end of the said linear light source is located. Preferably there is .

Moreover, the 1st aspect of this invention provides the planar illuminating device with which the said recessed part which arrange | positions the said inverter unit is formed including a resin member.
Further, according to the first aspect of the present invention, a plurality of notches are provided in a direction parallel to the linear light source at a position where the inverter unit is disposed in the recess, and according to the formation position of the notches, Provided is a planar illumination device in which a resin frame in which a groove for arranging the inverter unit is formed in a direction parallel to the linear light source is disposed on the upper surface of the recess, and is fitted into the entire area of the recess.

  According to a second aspect of the present invention, there is provided a liquid crystal display device characterized by using the planar illumination device according to the first aspect.

  According to the present invention, it is possible to reduce the thickness of the planar lighting device by providing a recess on one end side of the bottom of the lower housing and disposing the inverter unit in the recess. In addition, since a new member such as a housing for housing the inverter unit is not necessary, an increase in the number of parts can be prevented and productivity can be improved. In addition, since it is not necessary to provide a member for housing the inverter unit on the back surface of the planar lighting device, that is, the back surface of the housing, the flatness of the back surface can be improved, and the ceiling or wall surface of the planar lighting device can be improved. It is possible to easily attach to the.

The planar lighting device of the present invention will be described below.
FIG. 1 is a schematic perspective view showing a first embodiment of a planar illumination device of the present invention and showing an external appearance viewed from a 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 perspective view showing a main part of the planar illumination device shown in FIG. 4 is a cross-sectional view of the planar illumination device shown in FIG. 1 cut along a plane parallel to the linear light source. FIG. 5 is a partial cross-sectional view of an embodiment of the planar illumination 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 FIGS. 1, 2A to 2D, and FIG. 3, the planar illumination device 10 includes a plurality of linear light sources 12 and emits uniform light from a rectangular light emission surface 14a. The illuminating device main body 14, the illuminating device main body 14 accommodated therein, and a housing 16 in which a rectangular opening 16 a is formed on the light emitting surface 14 a side (front surface side), and disposed inside the housing 16 And a plurality of inverter units 18 used to turn on the plurality of linear light sources 12, and a power source 38 (FIG. 8) connected to the plurality of inverter units 18 for lighting the plurality of linear light sources 12, respectively. Reference).

Here, the illuminating device main body 14 is for emitting uniform light from the rectangular light emitting surface 14a. As shown in FIGS. 5, 6 and 7A, basically, A plurality of linear light sources 12 and a rectangular light exit surface 22a (light exit surface of the light guide plate 22) are formed on the light exit surface 14a side, and a plurality of parallel light sources 12 respectively accommodate the plurality of linear light sources 12 on the back side. A groove 22b is formed, and the light guide plate 22 in which the thinnest portion 22c having the thinnest thickness from the light exit surface 22a side to the back side is formed between adjacent parallel grooves 22b, and the light guide plate 22 is disposed on the light exit surface 22a side. The optical member unit 24 having a rectangular flat surface that forms the rectangular light emitting surface 14 a and the reflecting member 26 disposed along the back surface 22 d of the light guide plate 22 are provided.
6 shows only the unit light guide plate 23 having one parallel groove 22b that 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 the optical member unit 24 arranged on the upper portion of the light guide plate 22 is also a light exit surface 22 a that is a light exit surface of the light guide plate 22. Needless to say, they have substantially 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. 8), 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 light source such as a normal fluorescent tube (hot cathode tube; HCFL) or an external electrode tube (EEFL) can be used.
The inverter unit 18 and the power source 38 (see FIG. 8) 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 formed of a transparent resin, and as shown in FIG. 7B, a rectangular individual light emitting 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 paragraphs [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 paragraphs [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 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 emitting surface 23a from the thick portion 23b toward the thin end portion 23c. The illumination light propagated in the back surface portion 23e and the illumination light reflected from the inclined surface 23d and the reflecting member 26 arranged along the inclined surface 23d that forms 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. 7A, the light guide plate 22 has a structure in which unit light guide plates 23 adjacent to each other in the direction orthogonal to the parallel grooves 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 light exit 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 exit surface 22a.

  As shown in FIG. 7A, the light guide plate 22 may be a single light guide plate assembly integrally formed with a plurality of unit light guide plates 23 connected, but cost reduction and yield are achieved. Considering the improvement of the above and the ease of manufacture, a plurality of integrally formed light guide plate assemblies of the unit light guide plates 23 may be connected to provide a large light guide plate having a large area light exit 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, and the light exit 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. In addition, at this time, it is needless to say that the uniform planar light emitting surfaces of the plurality of light guide plate coupling bodies are coupled to each other, and the light guiding plate 22 forms a uniform planar light exit surface 22a. . 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 preferably has substantially the same size (area) as the light exit surface 22 a of the light guide plate 22.

  The optical member unit 24 makes the uniform illumination light emitted from the light exit surface 22a of the light guide plate 22 more uniform, and emits the illumination light with further improved uniformity from the light exit surface 14a of the illumination device body 14. As shown in FIG. 5 and FIG. 6, the illumination emitted from the light exit surface 22 a of the light guide plate 22 is formed with a microprism array that forms the light exit surface 14 a and is parallel to the parallel grooves 22 b of the light guide plate 22. A prism sheet 24a that improves light collection by improving light collection, a diffusion sheet 24b that diffuses and equalizes illumination light emitted from the light exit surface 22a of the light guide plate 22, and an output from the light exit surface 22a of the light guide plate 22 Is used to reduce the luminance unevenness of the illumination light, and is arranged on the transparent film 25a and the surface according to the luminance unevenness, and a large number of transmittance adjusting bodies 25 made of a diffuse reflector. And a transmittance adjusting member 24c provided with.

The transmittance adjusting member 24c is preferably provided on the side close to the light exit surface 22a of the light guide plate 22, but the arrangement order and number of the prism sheets 24a and the diffusion sheets 24b are not limited, and the optical member The prism sheet 24a, the diffusion sheet 24b, and the transmittance adjusting member 24c used in the unit 24 are not limited to those described above, and can make the illumination light emitted from the light exit surface 22a of the light guide plate 22 more uniform. Any optical member may be used as long as it is. 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.
In the case of the prism sheet 24a, the diffusion sheet 24b, and the transmittance adjusting member 24c, the optical members used in the optical member unit 24 are described in paragraphs [0028] to [0033] of Japanese Patent Application Laid-Open No. 2005-23497 related to the applicant's application. 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.

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 drive device 37 shown in FIGS. 8A and 8B 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. 8B 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.
Note that the inverter unit 18 in the illustrated example is arranged on a rectangular substrate portion 19 on which various circuits such as the drive circuit 18a, the tube current detection circuit 18c, and the voltage control oscillation circuit 18d are formed, and an upper portion of the substrate portion 19. And configured transformer 18b.

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 apparatus is basically configured as described above.

  On the other hand, as shown in FIG. 5, the housing 16 accommodates and supports the lighting device main body 14, and is sandwiched and fixed from the light emitting surface 14 a 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 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 side surfaces thereof. The concave (U-shaped) folding member 34 inserted between the side wall of the lower housing 30 and the side wall of the upper housing 32, and the back surface 22d of the light guide plate 22 are disposed at the bottom of the lower housing 30. A planar illumination is supported through the reflecting member 26. The entire apparatus main body 14 also has a light guide plate supporting member 36 for supporting.

  Here, as shown in FIG. 3 and FIG. 4, at the bottom of the lower housing 30, the lower housing 30 on the side where one end of the linear light source 12 is arranged when the lighting device main body 14 is installed, A recess 20 having a step 20a is formed along one side of one end 40 in the direction parallel to the parallel groove 22d (the direction indicated by arrow a in the figure) in a direction perpendicular to the axis of the linear light source 12. The The recess 20 houses a plurality of inverter units 18 inside the housing 16. The step 20 a has a height sufficient to accommodate the board portion 19 excluding the transformer 18 b of the inverter unit 18 in the recess 20. In addition, the length of the recess 20 in the direction parallel to the parallel groove 22d (the direction indicated by the arrow a in the drawing) may be long enough to accommodate the substrate portion 19.

  Here, when the inverter unit 18 is disposed in the recess 20 and the inverter unit 18 is housed in the housing 16, the transformer 18 b having a relatively large thickness of the inverter unit 18 is connected to the linear light source 12 and the light guide 12. The substrate portion 19 that is relatively thin so as not to come into contact with the optical plate 22 is parallel to the rear surface of the light guide plate 22 in a direction (indicated by an arrow a in the figure) parallel to the parallel groove 22d below the light guide plate 22. It is preferable to arrange in the above.

The planar lighting device of the illustrated example is provided on the outside of the casing, for example, on the back surface of the casing by providing a recess at one end of the bottom of the lower casing and disposing the inverter unit inside the casing (see FIG. 12), the thickness of the planar illumination device can be reduced, that is, the planar illumination device can be made thinner.
In addition, since there is no need to provide a member for housing the inverter unit and wiring for connecting the inverter unit and the linear light source on the back surface of the surface illumination device (the back surface of the lower housing), the number of parts can be increased. Can prevent and improve productivity. Moreover, the flatness of the back surface of a housing | casing can be improved and the attachment to the ceiling and wall surface of a planar illuminating device can be made easy.
Furthermore, since the planar lighting device of the illustrated example forms a bent structure (step 20a) in the lower housing when the recess 20 is formed, the rigidity of the lower housing can be improved.
In addition, by storing a part of the inverter unit (the substrate part in the illustrated example) parallel to the back surface of the light guide plate and positioned below the light guide plate, a direction parallel to the parallel grooves in the planar illumination device (the light source It is possible to reduce the length of the planar lighting device by reducing the length in the axial direction), and to improve the appearance of the planar lighting device by reducing the area of the non-opening portion of the upper housing.

Here, the housing 16 is preferably formed of a material having sufficient rigidity, such as metal or fiber reinforced plastic, in order to prevent the lighting device body 14 from being distorted.
Further, the side bracket 33 which is an L-shaped metal fitting improves the rigidity of the casing 16 by joining and reinforcing the four corners of the lower casing 30. 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 are used. Can do.
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, you may attach the reinforcement member which reinforces the recessed part of the concave folding member 34. FIG.
By arranging the folding member 34 in this way, the rigidity of the housing 16 can be increased, and light can be emitted uniformly and efficiently, while 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 being warped, and to obtain good optical characteristics without causing uneven brightness.

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.
The casing 16 includes an elastic member made of an elastic material such as rubber between the prism sheet 24a of the illuminating device body 14 and the peripheral portion of the opening 14a of the upper housing 30, and the prism sheet of the illuminating device body 14. A protective member for protecting the entire upper surface of 24a may be provided.
Heretofore, the first embodiment of the planar lighting device of the present invention has been described in detail.

Next, a second embodiment of the planar lighting device of the present invention will be described.
The planar illumination device of the present embodiment is basically the same as the planar illumination device of the first embodiment described above except for the shape of the storage unit of the inverter unit in the lower housing, and therefore the same member Are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 9 is a perspective view showing a main part of the planar illumination device 50 according to the present embodiment. FIG. 10 is an exploded perspective view showing a main part of the planar illumination device 50 shown in FIG. FIG. 11 is a partial perspective view showing a main part of the planar illumination device 50 shown in FIG. 9 to 11 include an end portion on the side where the inverter unit is disposed in a direction perpendicular to the parallel groove and a part of the parallel direction in the planar lighting device according to the second embodiment of the present invention. Indicates the area.

In the recess 54 of the lower housing 52 of the present embodiment, the position where the inverter unit 18 of the recess of the lower housing described in the first embodiment is arranged is a direction parallel to the parallel groove 22b (direction of arrow a). And has a configuration in which a plurality of notches 56 are formed and a resin frame 60 described later is placed on the upper surface of the recess 54.
The above-described resin frame 60 is formed such that a groove 62 is formed in accordance with the formation position of the notch 56 in the recess 54 and can be fitted in the entire area of the recess 54, and the notch 56 is formed in the recess 54. It is supported by the support part 58 (refer FIG. 10) arranged in the comb-tooth shape by having been performed, and is arrange | positioned on the upper surface of the recessed part 54 (refer FIG. 11).
The inverter unit 18 is disposed in the groove 62 of the resin frame 60. In the illustrated example, two inverter units are arranged in one groove, but one groove is formed for one inverter unit, and one inverter unit is arranged in one groove. Also good.

A support plate 64 is disposed between the resin frame 60 on which the inverter unit 18 is disposed and the light guide plate 22. The support plate 64 is integrated with the support surface 52a of the lower housing 52 to support the light guide plate 22 and the like. As described above, the level difference between the support surface 52a of the lower housing and the holding surface 58a of the holding portion 58 may be determined so that the support plate 64 has the same height as the support surface 52a of the lower housing 52. The holding portion 58, the resin frame 60, and the support plate 64 of the lower housing 52 are fixed by screwing.
The support plate 64 is made of resin as in the resin frame. In the present embodiment, the lower housing 52 is made of metal so as to have sufficient rigidity.

Here, in the present embodiment, metal is used for the lower housing 52, and a housing having sufficient rigidity can be obtained. However, when the inverter unit 18 is directly installed in the recess of the lower housing 52 made of metal as shown in the first embodiment, the metal lower housing 52 and the terminal on the high voltage side of the inverter unit 18 And since the distance with the electrode of the linear light source 12 connected to it is short, the problem that the brightness | luminance of the linear light source 12 falls under the influence of a leakage current or an eddy current arises.
To solve such a problem, the resin frame 60 is disposed between the metal lower housing and the inverter unit 18 as in the planar lighting device of the present embodiment, so that the high voltage portion (the above-described inverter unit) can be obtained. 18) and the lower housing 52 made of metal can be increased, thereby reducing the distributed capacitance generated around the high voltage portion. By reducing the size, it is possible to reduce the influence of luminance reduction due to housing mounting.
In this embodiment, the same effect as that of the first embodiment can be obtained.
The planar illumination device according to the second embodiment of the present invention has been described in detail.

  Here, the above-described planar illumination device of the present invention can be suitably used as a backlight unit of a liquid crystal display device.

  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.

For example, in the above-described embodiment, CCFL, HCFL, EEFL, or the like can be used as the linear light source. However, the planar illumination device according to the present invention is not limited to this, and a light emitting diode (LED) or a semiconductor is used. A light source such as a laser (LD) can also be used. When CCFL or the like is used as a linear light source, a device that converts direct current into alternating current, more specifically, a device that converts direct current power into high frequency alternating current power is used as an inverter unit for lighting the linear light source. When an LED, LD, or the like is used as the light source for the linear light source, a device (rectifier) that converts AC power into DC power may be used as the inverter unit. In the present invention, the inverter unit (converter) includes a device that converts AC power into DC power and a device that converts DC power into AC power.
In addition, when an LED or LD is used as the linear light source, a cylindrical or prismatic transparent light guide having the same length as the parallel grooves of the light guide plate is used, and the top and bottom surfaces of the light guide The LED may be arranged in such a manner that light from the LED enters from the top and bottom surfaces of the light guide and exits from the side of the light guide.

  Further, in the illustrated planar lighting device, various circuits such as a drive circuit, a tube current detection circuit and a voltage control oscillation circuit, and a transformer are set as one set, and this set is formed on a single substrate. Although the inverter unit is used, the planar lighting device according to the present invention is not limited to this, and a two-channel type inverter unit in which two sets are formed on one substrate may be used. A multi-channel type inverter unit formed on a single substrate may be used.

It is a schematic perspective view which shows the external appearance seen from the light-projection surface side of the planar illuminating device of the 1st Embodiment 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 perspective view which shows the principal part of the planar illuminating device shown in FIG. It is sectional drawing which cut | disconnected the planar illuminating device shown in FIG. 1 by the perpendicular | vertical surface parallel to a linear light source. 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. 5, (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 perspective view which shows the principal part of the planar illuminating device which concerns on the 2nd Embodiment of this invention. It is a disassembled perspective view which shows the principal part of the planar illuminating device shown in FIG. It is a fragmentary perspective view which shows the principal part of the planar illuminating device shown in FIG. It is principal part sectional drawing which shows an example of the conventional planar illuminating device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 50 Planar illuminating device 12 Linear light source 14 Illuminating device main body 14a Light emission surface 16 Case 16a Opening 18 Inverter unit 18a Drive circuit 18b Transformer 18c Tube current detection circuit 18d Voltage control oscillation circuit 20 Recessed part 22 Light guide plate 22a Light Exit surface 22b Parallel groove 22c Thinnest portion 22d Back surface 23 Unit light guide plate 23a Individual light exit surface 23b Thick portion 23c Thin end portion 23d Inclined surface 23e Inclined back surface portion 24 Optical member unit 24a Prism sheet 24b Diffusion film 24c Transmittance adjusting member 25a Transparent sheet 25b Transmittance adjustment body 26 Reflective member 26a Reflective film 26b Reflector 30 Lower housing 32 Upper housing 34 Folding member 36 Light guide plate support member 37 Drive device 38 Power supply 40 End portion 52 Lower housing 52a Support surface 54 Recessed portion 56 Cut Notch 58 holding part 58a holding surface 60 resin frame 62 groove 64 support plate

Claims (5)

A linear light source, a light guide plate for emitting light emitted from the linear light source from a planar light emitting surface, an inverter unit used for lighting the linear light source, and the opposite side of the light emitting surface A planar illumination device comprising a housing that is disposed on the surface of the linear light source and supports the light guide plate,
Have a recess for placing the inverter unit on one end side of the bottom portion of the housing,
The inverter unit includes a substrate and a transformer disposed on the substrate,
At least the inverter unit is disposed at a position where the transformer does not overlap the light guide plate in the recess,
Further, at least a part of the substrate of the inverter unit is arranged in parallel with the back surface of the light guide plate between the back surface of the light guide plate opposite to the light emitting surface and the housing. A planar lighting device.   2. The surface according to claim 1, wherein the recess extends on one end side of the bottom of the housing on the side where the end of the linear light source is located, in a direction perpendicular to the axis of the linear light source. Illuminator.   The planar lighting device according to claim 1, wherein the recess in which the inverter unit is disposed is formed including a resin member. A plurality of notches are provided in a direction parallel to the linear light source at a position where the inverter unit is disposed in the recess, and the inverter is parallel to the linear light source according to the formation position of the notches. The planar illumination device according to any one of claims 1 to 3, wherein a resin frame in which a groove for arranging a unit is formed is disposed on an upper surface of the recess and is fitted into the entire area of the recess.   A liquid crystal display device using the planar illumination device according to claim 1.

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