JP5991891B2 - Surface lighting device - Google Patents

Description

The present invention relates to a planar illumination device used as illumination means such as a liquid crystal display device.

Today's electronic devices are generally equipped with display devices as information display means and input means. In particular, a liquid crystal display device is generally used for an electronic apparatus having a large-screen display device such as a personal computer or an in-vehicle navigator. Since liquid crystal is not a self-luminous display element, for example, in a transmissive liquid crystal display device, illumination means for irradiating light to the liquid crystal panel is essential, and a transflective liquid crystal display device using external light However, auxiliary lighting means are provided to enable use in the dark. As a lighting means of such a liquid crystal display device, a so-called sidelight type backlight (planar lighting device), which mainly includes a light guide plate and a light source disposed on the side of the light guide plate, is thin. Since it has the advantage of being easy to make, it is widely used in combination with a liquid crystal display device. In addition, with the recent improvement in performance of white light emitting diodes (LEDs), a surface using white LEDs, which are point light sources, as a light source to further reduce the size and thickness of planar lighting devices and reduce power consumption. A state lighting device is also common.

Such a planar illumination device used for a large-screen display device is arranged on the light incident surface of the light guide plate in order to obtain a necessary light amount as the display region (backlight illumination region) expands. It is required to increase the number of LEDs. On the other hand, the increase in the number of LEDs is greatly affected by the temperature rise due to the heat generated from each LED, leading to a reduction in the light emission efficiency of the LEDs due to the temperature rise.

Therefore, in order to efficiently release the heat generated from the LED to the outside, a flexible printed circuit board (FPC) having a small thickness is used as a circuit board for mounting the LED, and the surface opposite to the surface on which the FPC LED is mounted is used. A configuration in which the surface (back surface) is brought into contact with a side surface of a heat radiating plate such as aluminum having a high thermal conductivity or a metal frame constituting a surface lighting device, and these are used as a heat radiating medium is widely adopted (for example, , See Patent Document 1).
In order to increase the thermal conductivity of the FPC and improve the heat dissipation, the applicants of the present invention have a side surface (light incident surface) 102a of the light guide plate 102 as in the planar illumination device 100 schematically illustrated in FIG. In addition, the LED 103 mounted on the flexible printed circuit board (hereinafter also referred to as FPC) 110 is arranged, and a surface that uses a metal material having excellent thermal conductivity such as aluminum as a material constituting the frame 105 that holds them integrally. The idea lighting device is invented. In this example, a wall is provided on the frame 105 so as to face the FPC 110, and this wall is used as the heat radiating plate 105a.

Furthermore, the structure which uses the double-sided FPC which has a conductor pattern on both front and back as shown in FIG. 8 for the mounting substrate of LED is employ | adopted (for example, refer patent document 2). In this example, as shown in FIG. 8, a conductor pattern 114 is formed on the front side surface 110 </ b> F of the FPC 110 so that the electrode terminal 103 a of the LED 103 is mounted on the land portion 112. A through hole 116 is formed in the conductor pattern 114 continuous to the land portion 112. A plating film 116 a is formed on the wall surface of the through hole 116. The cross-sectional shape of the through hole 116 is suitable when considering the workability, but is not necessarily limited thereto.

Then, at least a region A of the back side surface 110R of the FPC 110 where the through hole 116 is formed is joined to the heat radiating plate 105a via the high thermal conductive resin 118. The high thermal conductive resin 118 has electrical insulation, and for example, a high thermal conductivity in which a silicone-based resin material or a nonconductive thermal conductive filler such as alumina, aluminum nitride, or silicon carbide is added. Resin materials can be used.
In addition, a conductor pattern 120 that is continuous with the plating film 116a applied to the through hole 116 is formed at least in a region A where the through hole 116 is formed on the back side surface 110R of the FPC 110. The conductor patterns 114 and 120 are both formed on the surface of a flexible base film 122 made of polyimide or the like, and further covered with a flexible cover film 124 such as polyimide or the like so as to cover the conductor patterns 114 and 120. ing.

JP 2011-060485 A JP 2006-344472 A

By the way, recently, while the illumination area required for the planar illumination device is further expanded, further reduction in thickness of the planar illumination device is also demanded. For this reason, the shape of the FPC on which the LEDs arranged facing the light incident surface of the light guide plate are mounted also tends to be further elongated. For example, in the case of a planar illumination device having an illumination area of 7 inches, the shape of the FPC mounting portion is approximately 160 mm × 3 mm, and the increase in the so-called aspect ratio of the FPC is significant. As described above, when the aspect ratio of the FPC increases, the FPC is easily bent in a direction (short direction) perpendicular to the longitudinal direction in the assembly process of the planar lighting device, which is a factor that hinders assembly workability. Become. In addition, there is a concern that the adhesion between the FPC and the heat dissipation medium as described above deteriorates and the heat dissipation deteriorates.

In particular, when a structure in which the front and back conductor patterns 114 and 120 are electrically connected via the through holes 116 as shown in FIG. 8 is adopted, as shown in FIG. In order to electrically separate 114 and 120, it is necessary to provide a boundary portion BP that divides the conductor. Since there is no conductor (copper foil) in this boundary portion, the bending strength of the FPC is reduced as compared with a portion having a conductor, and the possibility that the above-described problem is significantly generated in the boundary portion BP is increased. .
The present invention has been made in view of the above problems, and the object of the present invention is to improve the assembly workability while enabling further expansion of the illumination area, and to the heat dissipation of the LED as the light source. It is providing the planar illuminating device which considered also.

(Aspect of the Invention)
The following aspects of the present invention exemplify the configuration of the present invention, and will be described separately for easy understanding of various configurations of the present invention. Each section does not limit the technical scope of the present invention, and some of the components of each section are replaced, deleted, or further while referring to the best mode for carrying out the invention. Those to which the above components are added can also be included in the technical scope of the present invention.

(1) A planar illumination device including a light guide plate, a point light source disposed on a side surface of the light guide plate, and a multilayered flexible printed board on which the point light source is mounted,
The flexible printed circuit board extends along a longitudinal direction of the flexible printed circuit board and is electrically connected to the point light source, and is formed with at least a first conductor pattern formed in one layer, and the first conductor A second conductor pattern formed on a layer different from the layer on which the pattern is formed, and the first conductor pattern and the second conductor pattern each have a boundary portion that divides the conductor in a plan view. A planar illumination device formed in a manner that intersects with each other.

In the planar illumination device described in this section, a flexible printed circuit board (FPC) on which a point light source disposed on a side surface of a light guide plate is mounted extends along the longitudinal direction of the FPC and is electrically connected to the point light source. that, at least, have a multilayer structure including a first conductor pattern formed on one layer and a second conductor pattern formed on a layer different from a layer where the first conductor pattern is formed Yes. Moreover, the first conductor pattern and the second conductor pattern are each formed in such a manner that the boundary portions that divide the conductor intersect each other in plan view. For this reason, the FPC is flattened by paying attention to the range in which the boundary portion is arranged (excluding the region where the conductor pattern does not exist near the edge of the FPC and therefore the boundary portion of the conductor pattern does not occur. The same applies hereinafter). When viewed, the region where the conductor portions of the first conductor pattern and the second conductor pattern do not exist in the thickness direction is limited to the region where the boundary portion intersects.
In other words, there is a wide range of conductor portions of the first conductor pattern or the second conductor pattern that extend along the longitudinal direction of the FPC and are electrically connected to the point light source , except for the region where the boundary portion intersects. Therefore, the bending strength of the FPC is ensured by narrowing the region where the conductor portion does not exist in any layer overlapping in the thickness direction of the FPC.

(2) In the above item (1), the portions of the boundary portion that divides the conductor formed in each of the first conductor pattern and the second conductor pattern intersect each other in plan view. Of the conductor pattern and the second conductor pattern, the boundary portion formed at least one of the conductor pattern and the planar shape formed in such a manner as to extend in an inclined manner with respect to the edge portion parallel to the longitudinal direction of the flexible printed circuit board Lighting device (Claim 2).
In the planar illumination device described in this section, a boundary portion formed on at least one of the first conductor pattern and the second conductor pattern is inclined with respect to an edge portion parallel to the longitudinal direction of the flexible printed circuit board. It is formed in an extending manner. For this reason, the other boundary part is orthogonal to the edge part parallel to the longitudinal direction, for example, as is usually seen as a conductor pattern, or substantially orthogonal (on processing accuracy and function) In the case of a configuration that is substantially orthogonal from the viewpoint, portions that intersect with each other in plan view are formed due to the difference in both angles.

(3) In the above item (2), the portions of the boundary portion that divides the conductor formed in each of the first conductor pattern and the second conductor pattern intersect each other in plan view. The boundary portion formed in the conductor pattern is formed in a manner extending in an inclined manner with respect to the edge portion parallel to the longitudinal direction of the flexible printed circuit board, and the boundary portion formed in the second conductor pattern is A planar illuminating device formed in such a manner as to extend in an inclined direction opposite to the first conductor pattern with respect to an edge portion parallel to the longitudinal direction (Claim 3).
The planar illumination device according to this section extends at an inclination with respect to an edge portion parallel to the longitudinal direction of the flexible printed circuit board at a boundary portion formed in both the first conductor pattern and the second conductor pattern. It has the part formed in the aspect. And when both boundary parts incline and extend in the reverse direction, the part which cross | intersects by planar view will be formed resulting from the angle difference of both.

(4) In the above items (1) to (3), a pair of pads to which a pair of electrodes of the point light source are electrically connected to one of the first conductor pattern and the second conductor pattern. The boundary portion is provided between the pair of pads formed or between the pads to which the electrodes on the opposite phase side of the point light source adjacent in the longitudinal direction of the flexible printed board are electrically connected. A planar lighting device (Claim 4).
In the planar illumination device described in this section, a pair of pads is formed on one of the first conductor pattern and the second conductor pattern, and a point light source is mounted so as to straddle the pair of pads. Is. A boundary portion is formed between the pair of pads or between the pads to which the positive and negative phase electrodes of the (separate) point light source adjacent to the longitudinal direction of the flexible printed board are electrically connected. Are provided, and the surface illumination device according to the above items (1) to (3) has a corresponding action.

(5) In the above item (4), there is provided a relay portion in which a through hole is formed to electrically connect the first conductor pattern and the second conductor pattern with the boundary portion interposed therebetween. A planar lighting device in which the pad is formed continuously to the relay portion (Claim 5).
In the planar illumination device described in this section, a relay portion is provided across at least one boundary portion of the first conductor pattern and the second conductor pattern, and the two relay portions sandwiching the boundary portion are provided, The pad according to the above item (4) is connected. In other words, a part or all of the first conductor pattern or the second conductor pattern is formed as a relay portion, and the boundary portion is formed in such a manner that the relay portion is divided. The pad is different from the other conductor pattern in which the pad is not formed by the through hole formed in the relay portion for electrically connecting the first conductor pattern and the second conductor pattern. Energization between layers is ensured.
Further, the boundary portions arranged so as to divide the relay portion are formed so as to intersect with each other in plan view, so that the conductor portions of the first conductor pattern and the second conductor pattern in the thickness direction. By limiting the region where the boundary does not exist to the region where the boundary portion intersects and narrowing the region where the conductor portion does not exist in any layer overlapping the thickness direction of the FPC, the bending strength of the FPC is ensured.

(6) In the above paragraphs (1) to (5), the conductor pattern divided by the boundary portion at a distance from the opposing edge portion of the conductor pattern divided by the boundary portion in the boundary portion; A planar illumination device in which a conductor portion of another system is disposed (claim 6).
The planar illumination device described in this section has a conductor part of a different system from the conductor pattern divided by the boundary part, spaced from the opposite edge part of the conductor pattern divided by the boundary part. By doing so, two narrow boundary portions are formed. And the area | region where the conductor part does not exist in a boundary part is narrowed further. Further, it is possible to give a function as an electric circuit to a conductor portion of another system.

(7) In the above items (1) to (6), the boundary portion is a planar illumination that extends continuously in the longitudinal direction along the edge portion in the vicinity of the edge portion parallel to the longitudinal direction. Device (claim 7).
In the planar illumination device described in this section, the boundary portion is also in the conductor pattern extending continuously in the longitudinal direction along the edge portion in the vicinity of the edge portion parallel to the longitudinal direction. To (6), the action corresponding to the planar illumination device is achieved.

(8) In the above items (1) to (7), one layer on which the first conductor pattern is formed is a layer located on the outermost surface, and is located on the side opposite to the layer located on the outermost surface. A planar illumination device in which the outermost surface layer is a layer on which the second conductor pattern is formed.
In the planar illumination device according to this section, one layer on which the first conductor pattern is formed is a layer located on the outermost surface, and the outermost layer located on the side opposite to the layer located on the outermost surface However, the planar lighting device having the FPC which is the layer in which the second conductor pattern is formed also exhibits the action corresponding to the planar lighting device according to the items (1) to (7). That is, the FPC of the planar lighting device according to this section is such that the first and second conductive patterns are formed on the outermost surface layers of the front and back surfaces in the case of a multilayer FPC having three or more layers as well as two layers. It is. When a pair of pads are formed on the conductor pattern, at least the pad portion is exposed to the outside from the outermost surface.

(9) A planar illumination device according to the items (1) to (8), wherein the opposing edge portions of the conductor pattern divided by the boundary portion are formed in a linear shape or an arc shape.
In the planar illumination device described in this section, from the above (1) to (1), regardless of whether the opposing edge portions of the conductor pattern divided by the boundary portion are linear or arcuate, The effect corresponding to the planar illumination device according to item 8) is exhibited.

(10) The planar illumination device according to (1) to (9), wherein the boundary portion is provided in a bent portion of the flexible printed board.
In the planar illumination device described in this section, the boundary portion is provided in a bent portion of the FPC, that is, a portion that is intentionally bent. Then, in a state where the FPC is viewed in plan, in an area where the conductor portions of the first conductor pattern and the second conductor pattern exist in the thickness direction, the bent shape of the FPC is stably maintained by plastic deformation of the conductor portion. It will be a thing.

Furthermore, the characteristic part of the flexible printed circuit board employed in the planar illumination device described in the above (1) to (10) is also used as an FPC of an electronic device other than the planar illumination device. 11) to (20).
(11) one first conductor pattern, at least including a flexible printed circuit board and the second conductor pattern, the formed layer different from the layer in which the conductor pattern is formed in said first formed layer The first conductor pattern and the second conductor pattern extend along the longitudinal direction of the flexible printed circuit board and are conducted.
Each of the first conductor pattern and the second conductor pattern includes a boundary portion that divides the conductor, and the boundary portions are arranged so as to intersect each other in plan view. Flexible printed circuit board.

(12) In the above item (11), the portions of the boundary portion that divides the conductor formed in each of the first conductor pattern and the second conductor pattern intersect each other in plan view.
A boundary portion formed on at least one of the first conductor pattern and the second conductor pattern is formed so as to extend in an inclined manner with respect to an edge portion parallel to the longitudinal direction. Flexible printed circuit board.
(13) In the above item (12), the portions of the boundary portion that divides the conductor formed in each of the first conductor pattern and the second conductor pattern intersect each other in plan view.
In the boundary part formed in the first conductor pattern, it is formed in an aspect extending in an inclined manner with respect to an edge part parallel to the longitudinal direction of the flexible printed circuit board, and
The boundary portion formed in the second conductor pattern is formed so as to extend in an inclined manner in an opposite direction to the first conductor pattern with respect to an edge portion parallel to the longitudinal direction. Flexible printed circuit board.
(14) In the above items (11) to (13), a pair of pads to which a pair of electrodes of a mounting component are electrically connected is formed on one of the first conductor pattern and the second conductor pattern. The boundary portion is provided between the pair of pads or between the pads to which the electrodes on the opposite phase side of the point light source adjacent in the longitudinal direction of the flexible printed board are electrically connected. A flexible printed circuit board characterized by that.
(15) In the above item (14), there is provided a relay portion in which a through hole for electrically connecting the first conductor pattern and the second conductor pattern is formed across the boundary portion. The flexible printed circuit board, wherein the pad is formed continuously with the relay portion.

(16) In the above paragraphs (11) to (15), a conductor pattern divided by the boundary portion at a distance from an opposing edge portion of the conductor pattern divided by the boundary portion, in the boundary portion; A flexible printed circuit board in which a conductor portion of another system is arranged.
(17) In the above items (11) to (16), the boundary portion extends continuously in the longitudinal direction along the edge portion in the vicinity of the edge portion parallel to the longitudinal direction. Flexible printed circuit board.
(18) In the above items (11) to (17), one layer on which the first conductor pattern is formed is a layer located on the outermost surface, and is located on the side opposite to the layer located on the outermost surface. A flexible printed circuit board, wherein the outermost surface layer is a layer on which the second conductor pattern is formed.
(19) The flexible printed circuit board according to (11) to (18), wherein the opposing edge portions of the conductor pattern divided by the boundary portion are formed in a linear shape or an arc shape.
(20) The flexible printed circuit board according to (11) to (19), wherein the boundary portion is provided in a bent portion of the flexible printed circuit board.
And according to the flexible printed circuit board described in the above items (11) to (20), the flexible printed circuit board according to the planar illumination device described in the above items (1) to (10) has a corresponding action. Is.

Since the present invention is configured as described above, it is possible to provide a planar illumination device that can further expand the illumination area, has good assembly workability, and also takes into consideration the heat dissipation of the LED as a light source. Is possible.

The structure of the flexible printed circuit board of the planar illuminating device concerning embodiment of this invention is shown, The top view which shows each layer which concerns on a 1st conductor pattern and a 2nd conductor pattern, and the state by which these were laminated | stacked The top view and sectional drawing which show are shown. The modification of FIG. 1 is shown. It shows another modification of FIG. 1 is a flexible printed circuit board of a planar lighting device according to an embodiment of the present invention, and shows a structure including a pair of pads to which a pair of electrodes of a point light source are electrically connected; The top view which shows each layer which concerns on a pattern and a 2nd conductor pattern, and the top view and sectional drawing which show the state by which these were laminated | stacked are shown. 5 shows a modification of FIG. It shows another modification of FIG. It is a perspective view which shows roughly the structure of the conventional planar illuminating device. FIG. 9 shows a flexible printed circuit board of the conventional planar lighting device shown in FIG. 8, (a) is a cross-sectional view showing a state where LEDs are surface-mounted, and (b) shows a flexible printed circuit board of (a). A front side view and (c) are back side views. FIG. 9 schematically shows a boundary portion that divides the conductor of the flexible printed board shown in FIG. 8, and is a plan view showing each layer related to the first conductor pattern and the second conductor pattern, and these are laminated. The top view and sectional drawing which show a state are shown.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Here, parts that are the same as or correspond to those in the prior art are given the same reference numerals as appropriate, and detailed descriptions thereof are omitted.
Each of the FPCs 10 illustrated in FIGS. 1 to 6 below is used as a substrate on which the LED 103 is mounted, similarly to the conventional FPC 110 shown in FIG. Is. Each of FIGS. 1 to 6 shows a part of an FPC having a large aspect ratio, and the illustrated portion has a configuration that is actually continuous in the horizontal direction of each drawing. For the entire configuration of the planar lighting device 100, refer to FIGS. 7 and 8 as appropriate.

The FPC 10A shown in FIG. 1 includes a first conductor pattern 12A formed in one layer, a second conductor pattern formed in a layer different from the layer in which the first conductor pattern is formed, and 14A. Is included. In the illustrated example, the FPC 10A has a two-layer configuration. One layer on which the first conductor pattern 12A is formed is a layer facing the front side. On the other hand, the layer located on the opposite side (back side) from this layer is the layer on which the second conductor pattern 14A is formed. The first conductor pattern 12A and the second conductor pattern 14A are respectively provided with boundary portions 12ABP and 14ABP that divide the conductor, and the boundary portions 12ABP and 14ABP intersect each other in plan view. It is what is arranged in.

Further, the portions (intersections) CP of the boundary portions 12ABP and 14ABP formed in each of the first conductor pattern 12A and the second conductor pattern 14A that divide the conductor intersect each other in plan view are In the boundary portion 12ABP formed in the conductor pattern 12A, at least a predetermined range (determined as appropriate) near the center in the short side direction (vertical direction in FIG. 1) of the FPC 10A is the longitudinal direction (horizontal direction in FIG. 1). ) With respect to the end edge portion 16 parallel to). On the other hand, also in the boundary portion 14ABP formed in the second conductor pattern 14A, at least a predetermined range (determined appropriately) near the center in the short direction of the FPC 10A is an end edge portion 16 parallel to the longitudinal direction of the FPC 10A. On the other hand, the first conductor pattern 12A is formed so as to extend in a direction opposite to the first conductor pattern 12A.
Note that one of the first conductor pattern 12A and the second conductor pattern 14A is formed in a mode orthogonal to the edge 16 (the boundary between the pair of pads 12Da of the FPC 10D in FIG. 4). (Refer to the example in which the portion 12DBP is provided.) The boundary portion of the other conductor pattern is formed so as to extend in a direction inclined with respect to the edge portion 16 parallel to the longitudinal direction of the FPC 10A. Also good. Even in this case, the intersection CP of the boundary portions 12ABP and 14ABP is formed.

As in the example of FIG. 1, the FPC 10 </ b> B shown in FIG. 2 is a layer on which the first conductor pattern 12 </ b> B is formed facing the front side, and is located on the opposite side (back side) to this layer. The layer is a layer in which the second conductor pattern 14B is formed. The first conductor pattern 12B and the second conductor pattern 14B are respectively provided with boundary portions 12BBP and 14BBP that divide the conductor, and the boundary portions 12BBP and 14BBP intersect each other in plan view. Is constituted.
Further, each of the boundary portions 12BBP and 14BBP is separated from the opposing edge portions 12BE and 14BE of the conductor patterns 12B and 14B divided by these boundary portions, and the conductor pattern 12B divided by the boundary portions 12BBP and 14BBP. , 14B and another system, conductor portions 18 and 20 are arranged. In the example shown in the drawing, these different-system conductor portions 18 and 20 are formed in a linear shape so that the central portions of the boundary portions 12BBP and 14BBP extend along the shapes of the edge portions 12BE and 14BE. Yes.

Similarly to the example of FIGS. 1 and 2, the FPC 10C shown in FIG. 3 is a layer in which one layer on which the first conductor pattern 12C is formed faces the front side, and the opposite side (back side) to this layer. The layer located at is a layer in which the second conductor pattern 14C is formed. The first conductor pattern 12C and the second conductor pattern 14C are respectively provided with boundary portions 12CBP and 14CBP that divide the conductors, and the boundary portions 12CBP and 14CBP intersect each other in plan view. Is constituted.
Further, each of the boundary portions 12CBP and 14CBP has a conductor pattern extending continuously in the longitudinal direction along the edge portion 16 in the vicinity of the edge portion 16 parallel to the longitudinal direction of the FPC 10C. is there.

The FPC 10D shown in FIG. 4 is a layer in which one layer on which the first conductor pattern 12D is formed faces the front side, and a layer located on the opposite side (back side) from this layer is the second conductor pattern. The point where 14D is formed is the same as the example in FIGS.
Further, in the example of FIG. 4, a pair of pads 12 </ b> Da to which a pair of electrodes of the LED 103 (so-called top view type LED) is electrically connected is formed on the first conductor pattern 12 </ b> D. A boundary portion 12DBP is provided between the pair of pads 12Da. The boundary between the pair of pads 12Da is generally formed in a mode orthogonal to the edge 16 as shown in FIG. 4, and this general pad shape is also used in this example. Is to follow.
On the other hand, the boundary part 14DBP similar to the example of FIGS. 1 and 2 is formed in the second conductor pattern 14D, whereby the boundary parts 12DBP and 14DBP intersect each other in plan view. Is constituted.

The FPC 10E shown in FIG. 5 is a layer in which one layer on which the first conductor pattern 12E is formed faces the front side, and a layer located on the opposite side (back side) from this layer is the second conductor pattern. The point where 14E is formed is the same as the example of FIGS. However, the pad 12Ea formed on the first conductor pattern 12E shown in FIG. 5 is one in which the electrodes on the positive / negative / negative phase side of the LED 103 adjacent (separate) in the longitudinal direction of the FPC 10E are electrically connected. And a pair is formed with each pad located outside the illustrated range (outside of the right and left in the figure).
Further, as a difference from the example of FIG. 4, the first conductor pattern 12E is a relay for electrically connecting the first conductor pattern 12E and the second conductor pattern 14E across the boundary portion 12EBP. The pad 12Ea is formed continuously with the relay portion. Moreover, a through hole (see the through hole 116 in FIG. 8) is formed in the whole or a part of the first conductor pattern 12E as the relay portion, and the first conductor pattern 12E and the first conductor pattern 12E are formed by this through hole. The second conductor pattern 14E is electrically connected. In other words, all or a part of the first conductor pattern 12E is formed as a relay portion, and the boundary portion 12EBP is formed in a manner of dividing the relay portion 12E. And the boundary part 12EBP formed in the conductor pattern 12E as a relay part is formed in the aspect orthogonal to the edge part 16 similarly to the form of the boundary part of pad 12Da shown by FIG. On the other hand, the second conductor pattern 14E is formed with a boundary portion 14EBP similar to the example of FIGS. 1, 2, and 4, and the boundary portions 12EBP and 14EBP intersect each other in plan view. Is constituted.

The first conductor pattern 12F of the FPC 10F shown in FIG. 6 is formed on the first conductor pattern 12A shown in FIG. 1 with the boundary portion 12EBP of the first conductor pattern 12E of the FPC 10E shown in FIG. Similarly to the boundary portion 12ABP, the edge portion 16 is formed so as to extend in an inclined direction with respect to the end edge portion 16 parallel to the longitudinal direction of the FPC 10F (left-right direction in FIG. 1). On the other hand, the second conductor pattern 14F is formed with boundary portions 14FBP similar to those in the examples of FIGS. 1, 2, 4, and 5, and the boundary portions 12FBP and 14FBP intersect each other in plan view. The intersection CP is formed.
Further, the first conductor pattern 12F as a relay portion is formed with a through hole (see the through hole 116 in FIG. 8), and is similar to the example of FIG. 5 in that it functions as a relay portion.

Now, according to the embodiment of the present invention configured as described above, the following operational effects can be obtained.
First, in the planar illumination device according to the embodiment of the present invention, the FPC (10A to 10F) on which the LED 103 disposed on the side surface of the light guide plate 102 is mounted is at least a first conductor formed in one layer. It has a multilayer structure including patterns (12A to 12F) and second conductor patterns (14A to 14F) formed in a layer different from the layer on which the first conductor pattern is formed. . In addition, the first conductor patterns (12A to 12F) and the second conductor patterns (14A to 14F) each have boundary portions (12ABP to 12FBP, 14ABP to 14FBP) that divide the conductors in a plan view. Are formed in such a manner.
For this reason, ranges in which the boundary portions (12ABP to 12FBP, 14ABP to 14FBP) are arranged (except for a range in which there is no conductor pattern near the edge portion 16 of the FPC, and thus no boundary portion of the conductor pattern can be generated). When the FPC (10A to 10F) is viewed in plan with a focus on the above, the conductor portions of the first conductor pattern (12A to 12F) and the second conductor pattern (14A to 14F) are arranged in the thickness direction of the FPC (10A to 10F). It is possible to limit the region where no exists to the intersection CP of the boundary portions (12ABP to 12FBP, 14ABP to 14FBP).

In other words, the first conductor pattern (12A to 12F) and the first conductor pattern (12A to 12F) and any layer overlapping in the thickness direction of the FPC (10A to 10F) except for the intersection CP of the boundary portions (12ABP to 12FBP, 14ABP to 14FBP) By narrowing the region of the second conductor pattern (14A to 14F) where the conductor portion does not exist, the bending strength of the FPC (10A to 10F) is ensured.
For this reason, in handling the FPC (10A to 10F), the occurrence of inadvertent bending is avoided, and the assembly workability is not hindered even in the assembly process of the planar lighting device 100. As a result, it is possible to avoid deterioration in adhesion between the FPC (10A to 10F) and the heat radiation medium (the heat radiation plate 105a of the frame 105 shown in FIG. 7) constituting the planar illumination device 100. It becomes. Therefore, the heat dissipation of the LED 103 is not impaired, and it is possible to prevent a decrease in luminance of the planar lighting device 100 due to the temperature increase of the LED 103.

  Here, as illustrated in FIG. 1 to FIG. 3 and FIG. 6, in the boundary portions 12ABP, 12BBP, 12CBP, and 12FBP formed in the first conductor patterns 12A, 12B, 12C, and 12F, It has the part formed in the aspect extended incline with respect to the edge 16 parallel to a longitudinal direction. Further, in the boundary portions 14ABP, 14BBP, 14CBP, and 14FBP formed in the second conductor patterns 14A, 14B, 14C, and 14F, the direction opposite to the first conductor pattern is formed with respect to the edge portion 16 that is parallel to the longitudinal direction. It has the part formed in the aspect extended in inclination. Then, due to the angular difference between the two, a crossing portion CP that intersects with each other in plan view is formed.

On the other hand, as illustrated in FIG. 4 and FIG. 5, the boundary portions 12DBP and 12EBP of the first conductor patterns 12Da and 12E are in relation to the edge portion parallel to the longitudinal direction so as to be normally seen as a conductor pattern. In the boundary portions 14DBP and 14EBP formed in an orthogonal manner and formed on the other side, the boundary portions 14DBP and 14EBP are formed in an aspect extending in a direction inclined with respect to the edge portion parallel to the longitudinal direction. Due to the difference, intersecting portions CP intersecting each other in plan view are formed.

Further, as illustrated in FIG. 4, even when the LED 103 is mounted so that the pair of pads 12Da is formed on the first conductor pattern 12D and straddles the pair of pads 12Da, the pair of pads 12Da By providing the boundary portion 12DBP between the two, the above-described effects can be obtained.
Alternatively, as illustrated in FIG. 5 and FIG. 6, even when the pads 12Ea and 12Fa are mounted with the electrodes on the positive and negative / negative phase sides of the LED 103 adjacent (separate) in the longitudinal direction of the FPCs 10E and 10F, By providing the boundary portions 12EBP and 12FBP on the first conductor patterns 12E and 12F located between the pads 12Ea and 12Fa, the above-described effects can be obtained.

  In the examples shown in FIGS. 5 and 6, the first conductor patterns 12E and 12F and the second conductor patterns 14E and 14F are sandwiched between the boundary portions 12EBP and 12FBP of the first conductor patterns 12E and 12F. First conductor patterns 12E and 12F are provided as two relay portions in which through holes (see the through holes 116 in FIG. 8) for electrical connection are formed. And by connecting pads 12Ea and 12Fa to these relay portions 12E and 12F, through the through holes of the first conductor patterns 12E and 12F, the pads 12Ea and 12Fa of the first conductor patterns 12E and 12F, and the pads Energization between different layers is ensured with the other conductor patterns 14E and 14F in which is not formed.

In the examples of FIGS. 5 and 6, the boundary portions 12EBP and 12FBP arranged so as to divide the relay portions 12E and 12F, and the boundary portions 14EBP and 14FBP of the other conductor patterns 14E and 14F, They are formed so as to intersect with each other in plan view. For this reason, the range in which the boundary portion is arranged (the range in which the relay portions 12E and 12F as conductor patterns in the vicinity of the end edge portion 16 of the FPCs 10E and 10F do not exist, and thus the boundary portion of the relay portions 12E and 12F cannot be generated. When the FPCs 10E and 10F are viewed in plan, paying attention to the above, the regions where the conductor portions of the first conductor patterns 12E and 12F and the second conductor patterns 14E and 14F do not exist in the thickness direction are defined as the boundary portions 12EBP and 14EBP. Can be limited to the intersection CP of 12 and the intersection CP of 12FBP and 14FBP. And it becomes possible to ensure the bending strength of FPC10E and 10F by narrowing the area | region where a conductor part does not exist in any layer which overlaps the thickness direction of FPC.

In addition, as in the example shown in FIG. 2, the conductor patterns 12B and 14E divided by the boundary portions 12BBP and 14BBP are separated by the boundary portions 12BBP and 14BBP at a distance from the opposing edge portions 12BE and 14BE. By arranging the conductor portions 18 and 20 of a different system from the conductor patterns 12B and 14E, the 12BBP and 14BBP become two narrow-width boundary portions. Thus, the bending strength of the FPC 10B is ensured by further narrowing the region where the conductor portion does not exist in the boundary portion. Moreover, it is also possible to give a function as an electric circuit to the conductor portions 18 and 20 of another system as necessary.
Further, as in the example shown in FIG. 3, the boundary portion 12CBP constitutes a conductor pattern extending continuously in the longitudinal direction along the edge portion 16 in the vicinity of the edge portion 16 parallel to the longitudinal direction of the FPC 10C. Even so, the bending strength of the FPC 10C can be ensured.

  In addition, since the examples of FIGS. 1 to 6 are all two-layer FPCs, one layer on which the first conductor patterns 12A to 12F are formed is a layer located on the outermost surface, and the outermost surface. The layer on the outermost surface located on the opposite side to the layer located at is the layer on which the second conductor patterns 12A to 12F are formed. However, even in the case of a multi-layer FPC having three or more layers made up of only two layers, the first and second conductive patterns are formed on the outermost surface layers of the front and back surfaces, so that the same as the above-described two-layer FPC The effect of this is achieved. Similarly to the example of FIGS. 4 to 6, when a pair of pads 12Da, 12Ea, and 12Fa is formed on the first conductor patterns 12D, 12E, and 12F, at least this pad portion is at the outermost surface. Will be exposed to the outside.

Further, in all of the examples of FIGS. 1 to 6, the opposing edge portions of the conductor patterns 12A to 12F and 14A to 14F divided by the boundary portions 12ABP to 12FBP and 14ABP to 14FBP are linearly formed. However, it can be appropriately formed in an arc shape, and even in this case, the above-described effects can be obtained.
4 to 6, pads 12Da, 12Ea, and 12Fa are formed on the first conductor patterns 12D, 12E, and 12F on the front surface side. If necessary, the second conductors on the back surface side are formed. Pads corresponding to the pads 12Da, 12Ea, and 12Fa may be formed on the patterns 14D, 14E, and 14F.
In addition, the boundary portions 12ABP to 12FBP and 14ABP to 14FBP are provided in the bent portions of the FPCs 10A to 10F, that is, the portions that are intentionally bent because of the arrangement in the planar illumination device 100. Also good. In this case, in a region where the conductor portions of the first conductor patterns 12A to 12F and the second conductor patterns 14A to 14F are present in the thickness direction in a state in which the FPC is viewed in plan, the plasticity of the conductor portions is present. Due to the deformation, it is possible to stably maintain the bent shape of the FPC.

10A, 10B, 10C, 10D, 10E, 10F: FPC
12A, 12B, 12C, 12D, 12E, 12F: First conductor pattern 12ABP, 12BBP, 12CBP, 12DBP, 12EBP, 12FBP: Boundary portion 12BE, 14BE: Edge portion 12Da, 12Ea, 12Fa: Pad 14A, 14B, 14C , 14D, 14E, 14F: second conductor pattern 14ABP, 14BBP, 14CBP, 14DBP, 14EBP, 14FBP: boundary part 18, 20: conductor part of another system CP: intersection part 100: planar illumination device, 102 light guide plate, 102a: side surface, 103: LED

Claims (8)

A planar illumination device including a light guide plate, a point light source disposed on a side surface of the light guide plate, and a flexible printed circuit board having a multilayer structure for mounting the point light source,
The flexible printed circuit board extends along a longitudinal direction of the flexible printed circuit board and is electrically connected to the point light source, and is formed with at least a first conductor pattern formed in one layer, and the first conductor A second conductor pattern formed in a layer different from the layer in which the pattern is formed,
The planar lighting device, wherein each of the first conductor pattern and the second conductor pattern is formed in such a manner that boundary portions that divide the conductor intersect each other in a plan view.
Lighting device. The portions formed in each of the first conductor pattern and the second conductor pattern and intersecting each other in plan view of the boundary part that divides the conductor are as follows:
A boundary portion formed on at least one of the first conductor pattern and the second conductor pattern is formed so as to be inclined and extend with respect to an edge portion parallel to the longitudinal direction of the flexible printed circuit board. The planar illumination device according to claim 1, wherein The portions formed in each of the first conductor pattern and the second conductor pattern and intersecting each other in plan view of the boundary part that divides the conductor are as follows:
The boundary part formed in the first conductor pattern is formed in an aspect extending in an inclined manner with respect to an edge part parallel to the longitudinal direction of the flexible printed circuit board, and
The boundary portion formed in the second conductor pattern is formed in such a manner that the boundary portion extends in a direction opposite to the first conductor pattern with respect to an edge portion parallel to the longitudinal direction. The planar illumination device according to claim 2. One of the first conductor pattern and the second conductor pattern is formed with a pair of pads to which a pair of electrodes of the point light source are electrically connected, and between the pair of pads or the flexible conductor 4. The boundary portion is provided between pads to which electrodes on the opposite phase side of point light sources adjacent in the longitudinal direction of the printed circuit board are electrically connected. The planar illumination device according to claim 1. A relay part in which a through hole is formed to electrically connect the first conductor pattern and the second conductor pattern across the boundary part is provided, and the pad is formed continuously from the relay part. The planar lighting device according to claim 4, wherein: is formed. The conductor portion separated from the conductor pattern divided by the boundary portion is arranged at a distance from the opposite edge portion of the conductor pattern divided by the boundary portion at the boundary portion. The planar illumination device according to any one of claims 1 to 5. The said boundary part is extended in the longitudinal direction continuously along this edge part in the vicinity of the edge part parallel to a longitudinal direction, The any one of Claim 1 to 6 characterized by the above-mentioned. Planar lighting device. The one layer on which the first conductor pattern is formed is a layer located on the outermost surface, and the outermost layer located on the opposite side of the layer located on the outermost surface is the second conductor pattern. The planar illumination device according to any one of claims 1 to 7, wherein the planar illumination device is a formed layer.