JP2018037397A - Planar lighting device and substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a planar lighting device and a substrate capable of suppressing generation of disconnection of wiring for connecting LEDs (Light Emitting Diode) in series.SOLUTION: A planar lighting device includes: a light guide plate for emitting light which has entered from a side surface; a plurality of light sources arranged on the side surface side, and for emitting the light which enters the side surface; a substrate having a mounting surface on which the plurality of light sources are mounted; and first wiring formed on an opposite surface on the opposite side from the mounting surface of the substrate, and for connecting the plurality of light sources in series.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a planar lighting device and a substrate.

  There is a planar illumination device in which a plurality of LEDs (Light Emitting Diodes) are arranged so as to face a light incident surface of a light guide plate. In such a planar lighting device, for example, a plurality of LEDs are arranged on the mounting surface side by side in the longitudinal direction of FPC (Flexible Printed Circuits), and wirings that connect adjacent LEDs in series (hereinafter referred to as series wiring). Is formed on the mounting surface (see, for example, Patent Document 1).

JP 2008-298905 A

  However, when the series wiring is formed on the mounting surface of the FPC, it becomes more difficult to dispose the cover lay (insulating layer) so as to cover the series wiring as the interval between adjacent LEDs is narrowed. In addition, the land portion where the cover layer is not formed and the wiring layer is exposed and is electrically connected to the LED and the electrode of the LED are electrically connected by solder. When such solder flows from the land portion to the series wiring having a narrow line width, stress concentration tends to occur at the end portion of the solder. This point will be described with reference to FIGS.

  9 to 11 are diagrams for explaining problems in the case where the serial wiring is formed on the mounting surface of the FPC. In FIG. 9, the electrode 101 a of the LED 101 and the wiring 104 a of the land portion 104 provided on the mounting surface 103 a of the FPC 103 are electrically connected by solder 105. Further, the electrode 102 a of the LED 102 adjacent to the LED 101 and the wiring 106 a of the land portion 106 provided on the mounting surface 103 a are electrically connected by solder 107. FIG. 9 shows a case where the solders 105 and 107 flow through the serial wiring 108 that connects the adjacent LEDs 101 and 102 in series. Here, when stress is applied in the direction indicated by arrows 110 and 111 in FIG. 10 due to handling such as rework, the stress concentrates on the end portion 105a of the solder 105 and the end portion 107a of the solder 107 shown in FIG. The disconnection 108a, 108b is likely to occur in the series wiring 108.

  As described above, when the series wiring is formed on the mounting surface of the FPC, it is difficult to arrange the cover lay, and stress concentration is likely to occur. Therefore, there is a high possibility that the series wiring is disconnected. Become. The tendency is that the smaller the interval between adjacent LEDs is, and the thinner the planar illumination device is, the smaller the wiring width (in the short direction of the FPC (direction intersecting the direction in which the LEDs are arranged)). ) Is considered to be more prominent as it becomes narrower.

  This invention is made | formed in view of the above, Comprising: It aims at providing the planar illuminating device and board | substrate which can suppress generation | occurrence | production of the disconnection of the wiring which connects LED in series.

  In order to solve the above-described problems and achieve the object, a planar illumination device according to one aspect of the present invention is disposed on a side surface of a light guide plate that emits light incident from a side surface, and is disposed on the side surface. A plurality of light sources that emit incident light, a substrate having a mounting surface on which the plurality of light sources are mounted, and an opposite surface opposite to the mounting surface of the substrate, wherein the plurality of light sources are connected in series. First wiring.

  According to one embodiment of the present invention, it is possible to suppress the occurrence of disconnection of wiring that connects LEDs in series.

FIG. 1 is a front view illustrating an example of the appearance of the planar illumination device according to the embodiment. 2 is a cross-sectional view taken along line AA in FIG. FIG. 3A is a front view schematically showing the opposite surface of the FPC according to the embodiment. FIG. 3B is a front view schematically showing the mounting surface of the FPC according to the embodiment. FIG. 4 is a front view illustrating a specific example of the opposite surface of the FPC according to the embodiment. FIG. 5 is a front view illustrating a specific example of a part of the mounting surface of the FPC according to the embodiment. FIG. 6 is an enlarged view of the FPC portion in FIG. FIG. 7 is a diagram for explaining a planar illumination device according to a modification of the embodiment. FIG. 8 is an enlarged view of a portion in FIG. FIG. 9 is a diagram for explaining a problem when the serial wiring is formed on the mounting surface of the FPC. FIG. 10 is a diagram for explaining a problem when the serial wiring is formed on the mounting surface of the FPC. FIG. 11 is a diagram for explaining a problem when the serial wiring is formed on the mounting surface of the FPC.

  Hereinafter, a planar illumination device and a substrate according to an embodiment will be described with reference to the drawings. In addition, the relationship of the dimension of each element in a drawing, the ratio of each element, etc. may differ from reality. Even between the drawings, there are cases in which portions having different dimensional relationships and ratios are included.

(Embodiment)
FIG. 1 is a front view illustrating an example of the appearance of the planar illumination device according to the embodiment. As shown in the example of FIG. 1, the shape of the planar illumination device 10 according to the embodiment is substantially rectangular when viewed from above. One end side in the longitudinal direction (Y-axis direction) of the planar illumination device 10 is covered with a light shielding sheet 30 including a first light shielding sheet 30a and a second light shielding sheet 30b. Further, the other end side in the longitudinal direction of the planar illumination device 10 is covered with a light shielding sheet 31. The planar illumination device 10 emits light from a light emitting region (also referred to as a light emitting area) 90 that is not covered with the light shielding sheets 30 and 31. That is, the light emitting area 90 is defined by the light shielding sheets 30 and 31. The planar illumination device 10 according to the present embodiment is used as a backlight of a liquid crystal display device. Such a liquid crystal display device is used, for example, in a smartphone.

  Here, in FIG. 1, the light shielding sheet 30 is wider than the light shielding sheet 31. This is because the light shielding sheet 31 covers a light guide plate 16, a diffusion sheet 18, and a prism sheet 19, which will be described later, existing below the light shielding sheet 31, while the light shielding sheet 30 is described later, which exists below the light shielding sheet 30. This is to cover a relatively wide area including the LED 14, the FPC 12, and the like described later in addition to the light guide plate 16, the diffusion sheet 18, and the prism sheet 19.

  2 is a cross-sectional view taken along line AA in FIG. As shown in FIG. 2, the planar lighting device 10 includes an FPC 12 as a substrate (mounting substrate), a fixing member 13, an LED 14 as a light source (point light source), a first connection member 15, a light guide plate 16, and a second connection. The member 17, the diffusion sheet 18, the prism sheet 19, the frame 20, the reflection sheet 21, and the light shielding sheet 30 are included.

  The frame 20 houses the FPC 12, the fixing member 13, the LED 14, the first connection member 15, the light guide plate 16, the second connection member 17, the diffusion sheet 18, the prism sheet 19, the reflection sheet 21, and the double-sided tape 22. The frame 20 has a side wall 20a and a bottom 20b. The frame 20 is, for example, a stainless steel sheet metal frame having high rigidity and light reflectance.

  The bottom portion 20b has a shape that spreads along a main surface 16b, which will be described later, of the light guide plate 16. The bottom portion 20b has a floor surface 20d that is a surface on the light guide plate 16 side. The floor surface 20d has a flat surface 20d_1 and a concave surface 20d_2 of a concave portion 20c described later. The light guide plate 16 is placed on the plane 20d_1. The side wall 20a is integrally formed in the direction in which light is emitted from the bottom 20b along the long side of a light incident surface 16c (to be described later) of the light guide plate 16 (the normal direction of the plane 20d_1 of the floor 20d, the positive direction of the Z axis). It is the part that stands up. The side wall 20a has a side surface 20e which is an inner side surface. Moreover, the bottom part 20b has the recessed part 20c. The recess 20c escapes the lower end of the FPC 12 that is formed to be recessed in a direction opposite to the direction in which light is emitted along the side surface 20e from the portion on the side surface 20e side of the floor surface 20d (the negative direction of the Z axis). It is a member. The recess 20c has a concave surface 20d_2. Since the first connecting member 15 is disposed in the recess 20c (specifically, on the concave surface 20d_2 of the recess 20c), the width of the recess 20c (the dimension of the recess 20c in the Y-axis direction) is larger than the first connection. The member 15 is formed to be relatively wide so that the member 15 is disposed in the recess 20c.

  The light guide plate 16 is formed in a rectangular shape in a top view using a transparent material (for example, polycarbonate resin). The light guide plate 16 has two main surfaces 16a and 16b and a light incident side surface (light incident surface) 16c which is a side surface on which the LED 14 is disposed. The light incident surface 16 c is a strip-shaped surface that extends in the short direction of the planar illumination device 10. The light emitted from the LED 14 is incident on the light incident surface 16c. The main surface 16a is an emission surface from which light incident from the light incident surface 16c (light emitted from the LED 14) is emitted. Therefore, in the following description, “main surface 16a” may be referred to as “exit surface 16a”. On the main surface 16b side that is the surface opposite to the exit surface 16a of the light guide plate 16, for example, an optical path changing pattern composed of a plurality of dots is formed. By forming the optical path changing pattern, the traveling direction of the light traveling in the light guide plate 16 is changed, and light is emitted from the emission surface 16a. That is, the planar illumination device 10 according to the embodiment is a so-called edge light type illumination device.

  The reflection sheet 21 reflects the light leaked from the main surface 16b opposite to the emission surface 16a and returns it to the light guide plate 16 again. The reflection sheet 21 is disposed between the main surface 16b of the light guide plate 16 and the floor surface 20d in a state of being fixed on the floor surface 20d (specifically, the flat surface 20d_1 of the floor surface 20d) by the double-sided tape 22. .

  The double-sided tape 22 is, for example, a white double-sided tape. One surface of the double-sided tape 22 is affixed to a part of the reflection sheet 21, and the other surface is affixed to the floor surface 20d (specifically, the flat surface 20d_1 of the floor surface 20d). Thereby, the double-sided tape 22 fixes the reflective sheet 21 on the floor surface 20d.

  The LED 14 is a point light source (point light source). The LED 14 is, for example, a pseudo white LED composed of a blue LED and a yellow phosphor. LED14 is formed in the substantially rectangular parallelepiped shape as a whole, and has the light emission surface 14a and the surface mounted in the mounting surface 12a mentioned later of FPC12 on the opposite side to the light emission surface 14a. The LED 14 is a so-called top view type LED. In the present embodiment, the plurality of LEDs 14 are arranged on the mounting surface 12a with a predetermined interval along the long side direction (X-axis direction) of the mounting surface 12a. That is, in a state where the light emitting surfaces 14a of the plurality of LEDs 14 are opposed to the light incident surface 16c of the light guide plate 16, the plurality of LEDs 14 are predetermined along the long side direction (X-axis direction) of the light incident surface 12c. Arranged at intervals. The plurality of LEDs 14 emit light toward the light incident surface 16c. As described above, the plurality of LEDs 14 emit light that is incident on the light incident surface 16c. The LED 14 may be a side view type LED.

  The FPC 12 is a strip-shaped substrate that extends in the short direction of the planar illumination device 10 (X-axis direction, long side direction of the light incident surface 16c). The FPC 12 has two main surfaces 12a and 12b. The two main surfaces 12 a and 12 b are strip-shaped surfaces extending in the short direction of the planar illumination device 10. Of the two main surfaces 12a and 12b, the main surface 12a is a mounting surface on which the LED 14 is mounted. For this reason, hereinafter, “main surface 12a” may be referred to as “mounting surface 12a”. The mounting surface 12a faces the surface of the LED 14 opposite to the light emitting surface 14a. The LED 14 is driven and lit by the control of a drive circuit (not shown) via the FPC 12. The main surface 12b is a surface opposite to the mounting surface 12a. For this reason, hereinafter, “main surface 12b” may be referred to as “opposite surface 12b”.

  The fixing member 13 fixes the FPC 12 to the side surface 20 e of the frame 20. The fixing member 13 is, for example, a double-sided tape. One surface of the fixing member 13 is attached to the opposite surface 12b of the FPC 12, and the other surface is attached to the side surface 20e, whereby the FPC 12 is fixed to the side surface 20e.

  The first connecting member 15 is disposed between the light guide plate 16 and the LED 14 and the floor surface 20d (specifically, the concave surface 20d_2 of the floor surface 20d), and optically or structurally connects the light guide plate 16 and the LED 14 to each other. Connect. Explaining with a specific example, the first connecting member 15 connects the light incident surface 16c of the light guide plate 16 and the light emitting surface 14a of the LED 14 with the optical axis of the light guide plate 16 and the optical axis of the LED 14 aligned. Connect. The 1st connection member 15 is a strip-shaped single-sided tape, and contains the adhesion layer (adhesive) 15a and the base material 15b.

  The base material 15b is, for example, PET, and the adhesive layer 15a is, for example, silicon or acrylic. The adhesive layer 15a adheres to at least a part of the main surface 16b of the light guide plate 16 near the LED 14 and also adheres to at least a part of the surface of the LED 14 near the light guide plate 16 near the light guide plate 16. Thereby, at least a part of the main surface 16 b of the light guide plate 16 and at least a part of the surface of the LED 14 on the floor surface 20 d side are attached to the first connecting member 15. As a result, the first connecting member 15 connects the light incident surface 16 c of the light guide plate 16 and the light emitting surface 14 a of the LED 14.

  Here, the case where the 1st connection member 15 is a double-sided tape is demonstrated. In this case, since the light guide plate 16 and the LED 14 are fixed to the floor surface 20d, if any force is applied to the planar illumination device 10 from the outside, the light guide plate 16 and the LED 14 can release the force. It is conceivable that it will be damaged. However, since the first connecting member 15 according to the present embodiment is a single-sided tape, the light guide plate 16 and the LEDs 14 are not fixed to the floor surface 20d, so that the light guide plate 16 and the LEDs 14 release an external force. Can do. For this reason, according to the planar illuminating device 10 which concerns on this embodiment, generation | occurrence | production of the damage of the light-guide plate 16 and LED14 can be suppressed.

  The first connecting member 15 has a member that absorbs light or a member that reflects light. For example, when the first connecting member 15 has a member that reflects light, the light emitted from the light emitting surface 14a of the LED 14 is reflected and returned to the light guide plate 16 again, so that the luminance can be improved. .

  The 2nd connection member 17 is arrange | positioned on the opposite side to the 1st connection member 15 with respect to the light-guide plate 16 and LED14, and connects the light-guide plate 16 and LED14 optically or structurally. Explaining with a specific example, the second connecting member 17 connects the light incident surface 16 c of the light guide plate 16 and the light emitting surface 14 a of the LED 14. The 2nd connection member 17 is arrange | positioned between the diffusion sheet 18 mentioned later, the light-guide plate 16, and LED14. The second connecting member 17 is, for example, a double-sided tape. One surface of the second connecting member 17 is affixed to at least a part of the light exit surface 16a of the light guide plate 16 near the LED 14 and is close to the light guide plate 16 on the surface opposite to the surface of the LED 14 on the floor surface 20d side. Affixed to at least a part of Thereby, at least a part of the emission surface 16a of the light guide plate 16 and at least a part of the surface opposite to the surface of the LED 14 on the floor surface 20d side are attached to the second connecting member 17. As a result, the second connecting member 17 connects the light incident surface 16 c of the light guide plate 16 and the light emitting surface 14 a of the LED 14.

  The other surface of the second connecting member 17 is attached to at least a part of the diffusion sheet 18 on the side wall 20a side. Thereby, the 2nd connection member 17 fixes the diffusion sheet 18 to the light-guide plate 16 and LED14. Accordingly, since the second connecting member 17 can suppress the diffusion sheet 18 from floating from the light guide plate 16, it suppresses deterioration of luminance characteristics such as luminance and luminance distribution of light emitted from the light emitting region 90. can do.

  The diffusion sheet 18 is disposed on the emission surface 16a side of the light guide plate 16, and diffuses light emitted from the emission surface 16a. Explaining with a specific example, the diffusion sheet 18 is disposed so as to cover at least a part of the light exit surface 16a and the surface of the LED 14 opposite to the floor surface 20d, and diffuses the light emitted from the light output surface 16a. . As described above, the diffusion sheet 18 is fixed to the light guide plate 16 and the LED 14 by the second connecting member 17.

  The prism sheet 19 is disposed on the surface opposite to the surface facing the emission surface 16a of the diffusion sheet 18, and performs light distribution control of the light diffused by the diffusion sheet 18 to perform light distribution control. Is emitted.

  The light shielding sheet 30 is disposed so as to cover a part of the prism sheet 19 on the side wall 20 a side, and blocks light emitted from a part of the light emitting surface 16 a of the light guide plate 16.

  The light shielding sheet 30 includes a first light shielding sheet 30a and a second light shielding sheet 30b. For example, the first light shielding sheet 30a is a single-sided tape that can shield light. One end side of the first light shielding sheet 30 a is attached to the outer surface of the side wall 20 a of the frame 20. For example, the 2nd light shielding sheet 30b is a double-sided tape which can block light. Of the two surfaces of the second light shielding sheet 30b, one end side of one surface is attached to the other end side of the first light shielding sheet 30a, and the other end side of one surface is on the side wall 20a side of the prism sheet 19. It is pasted. The other surface of the second light shielding sheet 30b is attached to a liquid crystal display device that uses the planar illumination device 10 as a backlight.

  The external connection portion 50 of the FPC 12 is inserted through a hole (not shown) formed across the side wall 20a side of the recess 20c and the lower end side of the side wall 20a, and is bent along the outer surface of the bottom portion 20b. Yes.

  FIG. 3A is a front view schematically showing the opposite surface 12b of the FPC 12 according to the embodiment, and FIG. 3B is a front view schematically showing the mounting surface 12a of the FPC 12 according to the embodiment. FIG. 4 is a front view illustrating a specific example of the opposite surface 12b of the FPC 12 according to the embodiment. FIG. 5 is a front view illustrating a specific example of a part of the mounting surface 12a of the FPC 12 according to the embodiment.

  In FIG. 3B, on the mounting surface 12a, five LED rows (light source rows) 14b, which are rows of LEDs 14 in which eight LEDs 14 are connected in series, are connected in parallel. That is, a total of 40 LEDs 14 are mounted on the mounting surface 12a. As shown in FIG. 3B, the plurality of LEDs 14 constituting the LED array 14b are mounted side by side in the X-axis direction (first direction) on the mounting surface 12a.

  An example of mounting the LED 14 will be described. As shown in FIG. 5, land portions 71 a to 71 d are formed on the mounting surface 12 a of the FPC 12. Here, the land portion 71a is electrically connected to a through hole 55a described later. The land portion 71b is electrically connected to a through hole 55b described later. One LED 14 is disposed in the region 80, the external electrode (anode) of the LED 14 is electrically connected to the land portion 71a, and the external electrode (cathode) of the LED 14 is electrically connected to the land portion 71b. . The land portion 71c is electrically connected to a through hole 55b described later, and the land portion 71d is electrically connected to a through hole 55a described later. The land portion 71c is electrically connected to the external electrode (cathode) of the LED 14 adjacent to the LED 14 in the minus direction of the X axis, and the land portion 71d is external to the LED 14 adjacent to the land portion 71d in the plus direction of the X axis. The electrode (anode) is electrically connected. As shown in FIG. 5, through holes 55a are formed in the areas of the land portions 71a and 71d in the XZ plan view. Further, a through hole 55b is formed in the area of the land portions 71b and 71c. Hereinafter, when all the land portions including the land portions 71a to 71d described above are described without distinction, they may be expressed as “land portions 71”. The same applies to the land portions 71 other than the land portions 71a to 71d described above.

  In addition, the total number of LED14, the number of LED14 which comprises LED row 14b, and the number of parallel are not restricted to this. The 40 LEDs 14 are referred to as an LED group 14c.

  As shown in FIGS. 3A, 3B and 4, the FPC 12 has through holes 51a to 51j. Hereinafter, when the ten through holes 51a to 51j are not distinguished from each other, they may be referred to as “through holes 51”.

  As shown in FIGS. 3A and 4, the FPC 12 includes routing wires 52 a to 52 j. 3B, among the eight LEDs 14 constituting the rightmost (rightmost) LED row 14b, the rightmost LED 14 is connected to the routing wiring 52a shown in FIGS. 3A and 4 through the through hole 51a. Yes. Also, in FIG. 3B, among the eight LEDs 14 constituting the rightmost LED row 14b, the leftmost LED 14 is connected to the routing wiring 52b shown in FIGS. 3A and 4 through the through hole 51b. That is, the routing wiring 52a is connected to the through hole 51a, and the routing wiring 52b is connected to the through hole 51b. The area 57a shown in FIG. 3A includes a part of the routing wirings 52a and 52b connected to the rightmost LED row 14b in FIG. 3B and the eight LEDs 14 constituting the rightmost LED row 14b in FIG. 3B in series. This is a region where wiring (series wiring 56 described later) connected to is formed on the opposite surface 12b.

  In FIG. 3B, among the eight LEDs 14 constituting the second LED row 14b from the right end, the rightmost LED 14 is connected to the routing wiring 52c shown in FIGS. 3A and 4 through the through hole 51c. ing. 3B, among the eight LEDs 14 constituting the second LED row 14b from the right end, the leftmost LED 14 is connected to the routing wiring 52d shown in FIGS. 3A and 4 through the through hole 51d. ing. That is, the routing wiring 52c is connected to the through hole 51c, and the routing wiring 52d is connected to the through hole 51d. The region 57b shown in FIG. 3A constitutes part of the routing wirings 52c and 52d connected to the second LED row 14b from the right end in FIG. 3B and the second LED row 14b from the right end in FIG. 3B. This is a region where wiring (series wiring 56 described later) for connecting the eight LEDs 14 in series is formed on the opposite surface 12b.

  As shown in FIG. 3A, the FPC 12 according to the present embodiment has three (plural) external connection portions 50a, 50b, and 50c on the lower end side (minus direction side of the Z-axis). The external connection portions 50a, 50b, and 50c are elongated strips. A conductive portion 53a is formed in the external connection portion 50a. The lead wirings 52a, 52b, 52c, and 52d are connected to the conductive portion 53a. That is, the FPC 12 has one external connection portion 50a for the two LED rows 14b. The conductive portion 53a is electrically connected to the drive circuit described above.

  3B, among the eight LEDs 14 constituting the third LED row 14b from the right end, the rightmost LED 14 is connected to the routing wiring 52e shown in FIGS. 3A and 4 through the through hole 51e. ing. In FIG. 3B, among the eight LEDs 14 constituting the third LED row 14b from the right end, the leftmost LED 14 is connected to the routing wiring 52f shown in FIGS. 3A and 4 through the through hole 51f. ing. That is, the lead wiring 52e is connected to the through hole 51e, and the lead wiring 52f is connected to the through hole 51f. 3A constitutes part of the routing wirings 52e and 52f connected to the third LED row 14b from the right end in FIG. 3B and the third LED row 14b from the right end in FIG. 3B. This is a region where wiring (series wiring 56 described later) for connecting the eight LEDs 14 in series is formed on the opposite surface 12b.

  Further, as shown in FIG. 3A, a conductive portion 53b is formed in the external connection portion 50b. The lead wiring 52e and the lead wiring 52f are connected to the conductive portion 53b. That is, the FPC 12 has one external connection portion 50b for one LED row 14b. Note that the conductive portion 53b is electrically connected to the drive circuit described above.

  In FIG. 3B, among the eight LEDs 14 constituting the second LED row 14b from the leftmost (left end), the rightmost LED 14 is routed as shown in FIGS. 3A and 4 through the through hole 51g. 52g. In FIG. 3B, among the eight LEDs 14 constituting the second LED row 14b from the left end, the leftmost LED 14 is connected to the routing wiring 52h shown in FIGS. 3A and 4 through the through hole 51h. ing. That is, the routing wiring 52g is connected to the through hole 51g, and the routing wiring 52h is connected to the through hole 51h. The area 57d shown in FIG. 3A constitutes part of the routing wires 52g and 52h connected to the second LED row 14b from the left end in FIG. 3B and the second LED row 14b from the left end in FIG. 3B. This is a region where wiring (series wiring 56 described later) for connecting the eight LEDs 14 in series is formed on the opposite surface 12b.

  Also, in FIG. 3B, among the eight LEDs 14 constituting the leftmost LED row 14b, the rightmost LED 14 is connected to the routing wiring 52i shown in FIGS. 3A and 4 through the through hole 51i. Also, in FIG. 3B, among the eight LEDs 14 constituting the leftmost LED row 14b, the leftmost LED 14 is connected to the routing wiring 52j shown in FIGS. 3A and 4 through the through hole 51j. That is, the routing wiring 52i is connected to the through hole 51i, and the routing wiring 52j is connected to the through hole 51j. 3A, a part of the routing wires 52i and 52j connected to the leftmost LED row 14b in FIG. 3B and the eight LEDs 14 constituting the leftmost LED row 14b in FIG. 3B are connected in series. This is a region where wiring (series wiring 56 described later) connected to is formed on the opposite surface 12b.

  Further, as shown in FIG. 3A, a conductive portion 53c is formed in the external connection portion 50c. The lead wiring 52g, the lead wiring 52h, the lead wiring 52i, and the lead wiring 52j are connected to the conductive portion 53c. That is, the FPC 12 has one external connection part 50c for the two LED rows 14b. Note that the conductive portion 53c is electrically connected to the drive circuit described above.

  Hereinafter, when the external connection units 50a to 50c are described without being distinguished from each other, they may be expressed as “external connection unit 50”. Further, when the routing wirings 52a to 52j are described without being distinguished from each other, they may be expressed as “the routing wiring 52”. The routing wiring 52 is an example of a second wiring. Moreover, when it demonstrates without distinguishing the electroconductive parts 53a-53c, it may describe with "the electroconductive part 53".

  Here, with reference to FIG. 4, the specific example of the electroconductive parts 53a-53c is demonstrated. As shown in FIG. 4, the conductive portion 53a includes a connection pad 54a, a connection pad 54b, and a connection pad 54c. The lead wire 52a is connected to the connection pad 54a, the lead wire 52c is connected to the connection pad 54b, and the lead wire 52b and the lead wire 52d are connected to the connection pad 54c. For example, the routing wiring 52a is connected to the cathode of the rightmost LED 14 among the eight LEDs 14 constituting the rightmost LED row 14b in FIG. 3B. Further, the routing wiring 52b is connected to the anode of the leftmost LED 14 among the eight LEDs 14 constituting the rightmost LED row 14b in FIG. 3B. The routing wiring 52c is connected to the cathode of the rightmost LED 14 among the eight LEDs 14 constituting the second LED row 14b from the right end in FIG. 3B. Further, the routing wiring 52d is connected to the anode of the leftmost LED 14 among the eight LEDs 14 constituting the second LED row 14b from the right end in FIG. 3B.

  The conductive portion 53b includes a connection pad 54d and a connection pad 54e. A lead wiring 52e is connected to the connection pad 54d, and a lead wiring 52f is connected to the connection pad 54e. For example, the routing wiring 52e is connected to the cathode of the rightmost LED 14 among the eight LEDs 14 constituting the third LED row 14b from the right end in FIG. 3B. Further, the routing wiring 52f is connected to the anode of the leftmost LED 14 among the eight LEDs 14 constituting the third LED row 14b from the right end in FIG. 3B.

  The conductive portion 53c includes a connection pad 54f, a connection pad 54g, and a connection pad 54h. The lead wire 52g is connected to the connection pad 54f, the lead wire 52i is connected to the connection pad 54g, and the lead wire 52h and the lead wire 52j are connected to the connection pad 54h. For example, the routing wiring 52g is connected to the cathode of the rightmost LED 14 among the eight LEDs 14 constituting the second LED row 14b from the left end in FIG. 3B. Further, the lead wiring 52h is connected to the anode of the leftmost LED 14 among the eight LEDs 14 constituting the second LED row 14b from the left end in FIG. 3B. Further, the routing wiring 52i is connected to the cathode of the rightmost LED 14 among the eight LEDs 14 constituting the leftmost LED row 14b in FIG. 3B. Further, the routing wiring 52j is connected to the anode of the leftmost LED 14 among the eight LEDs 14 constituting the leftmost LED row 14b in FIG. 3B.

  Hereinafter, when the connection pads 54a to 54h are described without being distinguished from each other, they may be referred to as “connection pads 54”.

  As described above, the routing wiring 52 connected to each LED row 14b (a plurality of LEDs 14 (eight LEDs 14 in this embodiment)) is formed on the opposite surface 12b opposite to the mounting surface 12a of the FPC 12. The lead wiring 52 is a wiring extending from both ends of each LED row 14b (eight LEDs 14 in this embodiment).

  As shown in FIG. 3A, wiring (series wiring) 56 that connects two adjacent LEDs 14 in series is formed on the opposite surface 12b of the FPC 12 in accordance with the number of LEDs 14 connected in series. . That is, the FPC 12 includes a series wiring 56. For example, in FIG. 3A, the leftmost (left end) series wiring 56 (hereinafter referred to as the left end series wiring) is the most of the eight LEDs 14 constituting the rightmost (right end) LED row 14b in FIG. 3B. It is connected to the external electrode (anode) of the right LED 14 via a through hole 55a. Further, the left end series wiring 56 includes an external electrode (cathode) of the LED 14 adjacent to the rightmost LED 14 among the eight LEDs 14 constituting the rightmost (right end) LED row 14b in FIG. 3B, and the through hole 55b. Is connected through. Similarly, the other series wirings 56 electrically connect two adjacent LEDs 14 in series via the through holes 55a and 55b. That is, one end of the series wiring 56 is connected to one of the two adjacent LEDs 14 via the through hole 55a, and the other end is connected to the other LED 14 via the through hole 55b. The serial wiring 56 is an example of a first wiring, the through hole 55a is an example of a first through hole, and the through hole 55b is an example of a second through hole. The through holes 55a and 55b are, for example, blind via holes (BVH).

  A cover lay (not shown) is disposed on the opposite surface 12 b so as to cover the series wiring 56 and the routing wiring 52. That is, the FPC 12 includes a coverlay.

  In the planar lighting device 10 according to the present embodiment, the series wiring 56 is formed not on the mounting surface 12a on which the LEDs 14 of the FPC 12 are mounted, but on the opposite surface 12b opposite to the mounting surface 12a. In the planar lighting device 10 according to this embodiment, the coverlay is not disposed on the mounting surface 12b, and the coverlay is disposed on the opposite surface 12b. Here, since the LED 14 is not mounted on the opposite surface 12b, there are relatively few restrictions on the shape of the coverlay to be arranged. For this reason, it is easier to dispose a cover lay on the opposite surface 12b than to dispose a cover lay on the mounting surface 12a. Therefore, the planar lighting device 10 according to the present embodiment can easily arrange a coverlay that protects the series wiring 56 and the lead wiring 52 from disconnection.

  Moreover, since electrical components such as the LED 14 are not mounted on the opposite surface 12b, the degree of freedom of the pattern shape of the series wiring 56 is relatively large. For example, the series wiring 56 can be monotonous with a relatively large line width. Furthermore, since no solder is required for the series wiring 56, the strength of the series wiring 56 can be increased, and the occurrence of disconnection of the series wiring 56 due to stress concentration at the end of the solder can be suppressed.

  FIG. 6 is an enlarged view of a portion 70 of the FPC 12 in FIG. As shown in FIG. 6, the series wiring 56 is a wiring that extends in the X-axis direction (the direction in which the plurality of LEDs 14 are arranged) and has an end portion that forms an arc. Further, as shown in FIG. 6, the lead wiring 52 d is formed on the opposite surface 12 b so as not to contact (interfere) with the series wiring 56. Specifically, for example, as shown in FIG. 6, the series wiring 56 is formed in the central portion in the short side direction (Z-axis direction) of the opposite surface 12 b of the FPC 12. In addition, the center part in the short side direction of the opposite surface 12b refers to a part in a certain range from the center in the short side direction of the opposite surface 12b, for example. And in the range where the series wiring 56 is not formed in the long side direction (X-axis direction) of the opposite surface 12b, the routing wiring 52d is in the central portion of the opposite surface 12b in the short side direction and the long side direction of the opposite surface 12b. And is branched into two (plural) wirings at a portion facing the end of the series wiring 56. In the range where the series wiring 56 is not formed in the long side direction of the opposite surface 12b, two branched wirings are formed on both sides of the series wiring 56 in the short side direction of the opposite surface 12. Similarly to the lead wiring 52d, the lead wirings 52a, 52d to 52g, 52j are formed on the opposite surface 12b so as not to contact the series wiring 56. Thereby, generation | occurrence | production of the short circuit (short) of LED14 can be suppressed.

  The planar lighting device 10 according to the present embodiment has been described above. As described above, according to the planar illumination device 10 according to the present embodiment, it is possible to suppress the occurrence of disconnection of the series wiring (wiring that connects the LEDs 14 in series) 56.

  The routing wiring 52 connected to the anode of the LED 14 described above may be connected to the cathode of the LED 14, and the routing wiring 52 connected to the cathode of the LED 14 described above may be connected to the anode of the LED 14. As described above, when the connection of the routing wiring 52 is changed between the cathode and the anode, the series wiring 56 is connected to the external electrode (cathode) of the LED 14 via the through hole 55a, and is connected via the through hole 55b. The external electrode (anode) of the LED 14 is connected.

(Modification of the embodiment)
In the embodiment described above, the case where there are three external connection units 50 has been described, but the number of external connection units 50 is not limited thereto. For example, the number of external connection units 50 may be reduced to two. Therefore, such an embodiment will be described as a planar illumination device according to a modification of the embodiment. In the description of the first modification, the same components as those in the above-described embodiment may be denoted by the same reference numerals and description thereof may be omitted.

  The planar illumination device according to the modification is different from the planar illumination device 10 according to the above-described embodiment in that only the external connection portions 50a and 50c among the above-described external connection portions 50a to 50c are provided. FIG. 7 is a diagram for explaining a planar illumination device according to a modification of the embodiment. FIG. 8 is an enlarged view of a portion 81 in FIG.

  As shown in FIG. 7, in the planar lighting device according to the modification, the lead wiring 52e extends toward the external connection portion 50a. The lead wiring 52e is connected to the connection pad 54a or the connection pad 54b. Further, the wiring lines 52d and 52e according to the modification have a narrower line width than the wiring lines 52d and 52e according to the embodiment. This is because the routing wiring 52d and the routing wiring 52e extend toward the same external connection portion 50 (external connection portion 50a).

  As shown in FIG. 8, the routing wiring 52e overlaps with the routing wiring 52d in the Z-axis direction. That is, the routing wiring 52d extending from one LED row 14b and the routing wiring 52e extending from the other LED row 14d overlap in the Z-axis direction (second direction) intersecting the X-axis direction.

  Further, in the planar lighting device according to the modification, although not shown, the lead wiring 52f extends toward the external connection portion 50c. The lead wiring 52f is connected to the connection pad 54h. In addition, the wiring lines 52f and 52g according to the modification are narrower than the wiring lines 52f and 52g according to the embodiment. This is because the routing wiring 52f and the routing wiring 52g extend toward the same external connection portion 50 (external connection portion 50c).

  The routing wiring 52f overlaps the routing wiring 52g in the Z-axis direction. That is, the routing wiring 52g extending from one LED row 14b and the routing wiring 52f extending from the other LED row 14d overlap in the Z-axis direction (second direction) intersecting the X-axis direction.

  As described above, the number of the external connection portions 50 can be reduced by overlapping the routing wiring 52 extending from one LED row 14b and the routing wiring 52 extending from the other LED row 14d in the Z-axis direction. it can.

  In the above-described embodiment and modification, the case where the routing wiring 52 is formed on the opposite surface 12b of the FPC 12 has been described. However, the routing wiring 52 may be formed on the mounting surface 12a of the FPC 12. For example, even if the LED 14 is mounted on the mounting surface 12a, the routing wiring 52 may be formed on the mounting surface 12a when a region (space) for forming the routing wiring 52 can be secured on the mounting surface 12a.

  Further, in the above-described embodiments and modifications, the example in which all the series wirings 56 are formed on the opposite surface 12b of the FPC 12 has been described. However, some of the series wirings 56 may be formed on the opposite surface 12b of the FPC 12 and the other series wirings 56 may be formed on the mounting surface 12a of the FPC 12. Further, all the series wirings 56 may be formed on both the opposite surface 12b of the FPC 12 and the mounting surface 12a. That is, for all the series wirings 56, a part of the series wiring 56 may be formed on the opposite surface 12b, and the other part may be formed on the mounting surface 12a.

  The embodiment and the modification have been described above. It should be noted that the present invention is not limited to the above embodiment and the above modification. What was comprised combining each component mentioned above suitably is also contained in this invention. Further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspect of the present invention is not limited to the above-described embodiment, and various modifications can be made.

10 Planar illumination device 12 FPC (substrate)
13 Fixing member 14 LED (light source)
14b Light source array 15 1st connection member 15a Adhesive layer 15b Base material 16 Light guide plate 17 2nd connection member 18 Diffusion sheet 19 Prism sheet 20 Frame 20a Side wall 20b Bottom part 20c Recessed part 20d Floor surface 20e Side surface 30 Light-shielding sheet 30a First light-shielding sheet 30b 2nd light shielding sheet 50a-50c External connection part 51a-51j Through hole 52a-52j Lead wiring (2nd wiring)
53a to 53c Conductive portions 54a to 54h Connection pads 55a and 55b Through holes (first through hole, second through hole)
56 Series wiring (first wiring)

Claims (12)

A light guide plate that emits light incident from the side surface;
A plurality of light sources arranged on the side surface and emitting light incident on the side surface;
A substrate having a mounting surface on which the plurality of light sources are mounted;
A first wiring that is formed on an opposite surface of the substrate opposite to the mounting surface and connects the plurality of light sources in series;
A planar lighting device.   The first wiring extends in a direction in which the plurality of light sources are arranged, and one end is connected to one of the two adjacent light sources via a first through hole, and the other end is connected to the other light source. The planar illumination device according to claim 1, wherein the planar illumination device is connected via a second through hole.   3. The apparatus according to claim 1, further comprising a second wiring extending from both ends of the light source array including the plurality of light sources connected in series and formed so as not to contact the first wiring on the opposite surface. The surface illumination device described. The plurality of light sources connected in series are mounted side by side in a first direction on the mounting surface,
The first wiring is formed at a central portion in a second direction intersecting the first direction on the opposite surface,
In a range where the first wiring is not formed in the first direction on the opposite surface, the second wiring is formed in a central portion in the second direction on the opposite surface, and the first wiring Branched into a plurality of wires at the portion facing the end,
In the range where the first wiring is formed in the first direction of the opposite surface, the plurality of wirings are formed on both sides of the first wiring in the second direction of the opposite surface.
The planar illumination device according to claim 3. The plurality of light sources connected in series are mounted side by side in a first direction on the mounting surface,
A plurality of the light source rows are arranged in the first direction on the mounting surface,
The planar shape according to claim 3 or 4, wherein a second wiring extending from one light source row and a second wiring extending from another light source row overlap in a second direction intersecting the first direction. Lighting device.   The planar illumination device according to any one of claims 1 to 5, further comprising a cover lay disposed on the opposite surface of the mounting surface and the opposite surface so as to cover the first wiring. A substrate having a mounting surface on which a plurality of light sources are mounted,
A substrate comprising a first wiring that is formed on an opposite surface of the substrate opposite to the mounting surface and connects the plurality of light sources in series.   The first wiring extends in a direction in which the plurality of light sources are arranged, and one end is connected to one of the two adjacent light sources via a first through hole, and the other end is connected to the other light source. The substrate according to claim 7, which is connected through a second through hole.   9. The apparatus according to claim 7 or 8, further comprising a second wiring extending from both ends of the light source array including the plurality of light sources connected in series and formed on the opposite surface so as not to contact the first wiring. The substrate described. The plurality of light sources connected in series are mounted side by side in a first direction on the mounting surface,
The first wiring is formed at a central portion in a second direction intersecting the first direction on the opposite surface,
In a range where the first wiring is not formed in the first direction on the opposite surface, the second wiring is formed in a central portion in the second direction on the opposite surface, and the first wiring Branched into a plurality of wires at the portion facing the end,
In the range where the first wiring is formed in the first direction of the opposite surface, the plurality of wirings are formed on both sides of the first wiring in the second direction of the opposite surface.
The substrate according to claim 9. The plurality of light sources connected in series are mounted side by side in a first direction on the mounting surface,
A plurality of the light source rows are arranged in the first direction on the mounting surface,
The board | substrate of Claim 9 or 10 with which the 2nd wiring extended | stretched from one light source row | line | column and the 2nd wiring extended | stretched from another light source row | line | column overlap in the 2nd direction which cross | intersects the said 1st direction.   The substrate according to any one of claims 7 to 11, further comprising a coverlay disposed on the opposite surface of the mounting surface and the opposite surface so as to cover the first wiring.

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