JP6247350B2 - Surface lighting device - Google Patents

Description

  The present invention relates to a sidelight type planar illumination device in which a light source is disposed on a side of a light guide plate.

In recent years, in backlights used for liquid crystal display devices and the like, there is an increasing demand for higher brightness in order to further improve the visibility of the display screen.
However, the current connection wiring pattern shape formed on a circuit board on which an LED (Light Emitting Diode) as a light source is mounted has a limit on the distance between the LEDs that can be mounted, and the number of LED lamps is limited. .

  In addition, there exist the following patent documents 1 and 2 as a literature well-known invention concerning this application.

Japanese Patent Laid-Open No. 2004-233809 JP 2006-237320 A

FIG. 5A is a plan view showing a light source part of a conventional sidelight type backlight, and FIG. 5B is a circuit board (circuit board on which an LED is mounted) in the light source part of the conventional sidelight type backlight. FIG.
As shown in FIG. 5A, in the conventional sidelight type backlight, a plurality of LEDs 101 mounted on a substrate 102 are disposed in contact with the side end face 103s of the light guide plate 103. The plurality of LEDs 101 irradiate light from the side end surface 103 s of the light guide plate 103 to the inside thereof.

  The substrate 102 on which the plurality of LEDs 101 are mounted is FPC (Flexible Printed Circuits), and its surface is covered with a coverlay 104 of an insulating layer as shown in FIG. A land 102r to which a pair of electrodes (not shown) of each LED 101 is connected is exposed from the opening 104k of the coverlay 104 including a part of a connection wiring (conduction pattern) connected to the land 102r. . In other words, a part of the connection wiring that connects the lands 102 r facing each other of the adjacent LEDs 101 is covered with a part of the cover lay 104. On the substrate 102, a plurality of pairs of lands 102r corresponding to the pair of electrodes of the respective LEDs 101 are arranged at a pitch pt1 (see FIG. 5B).

  By the way, as described above, the backlight of a liquid crystal panel used for a portable terminal (PDA: Personal Digital Assistant), that is, a planar illumination device, is required to have higher luminance. As one of countermeasures, a configuration in which more LEDs 101 are arranged on a light incident surface (side end surface 103 s) that is a side surface of the light guide plate 103 has been studied. In this case, the following two problems arise.

As a first point, as described in Patent Document 1, when all the LEDs are driven in series, the driving voltage becomes too large.
As a second point, as described in Patent Document 2, it is difficult to provide a cover lay between adjacent LEDs due to the processing limit of the cover lay and the limit of the attaching position accuracy with respect to the connection wiring. If there is no coverlay on the connection wiring arranged between adjacent LEDs, there is a concern about disconnection due to insufficient adhesive strength.

Of the above two problems (problems), the first point can be solved by reducing the driving voltage by driving the configuration of Patent Document 1, that is, by driving all the LEDs 101 into a plurality of groups.
However, for the second point, in the case of adopting the configuration of Patent Document 1, that is, the configuration in which all LEDs are divided into a plurality of groups and arranged so that LEDs belonging to different groups are adjacent to each other, The connection wiring disclosed in Patent Document 2 cannot be employed as it is.

  This is because in Patent Document 2, it is assumed that adjacent LEDs are connected in series, and therefore, in the configuration of Patent Document 1, adjacent LEDs in different groups are connected. That is, in the configuration of Patent Document 1, the LEDs of the same group cannot be connected in series because the LEDs of the same group are connected in series.

  In addition to the above two problems (problems), in order to stably achieve the illumination characteristics (high brightness and uniform illumination) of the planar illumination device at a high level, all the LEDs are accurately placed at predetermined positions. Need to be fixed. For this purpose, it is necessary to perform self-alignment with high accuracy when the LED is mounted on the FPC (land).

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a planar illumination device that has high reliability and can stably achieve high luminance and uniform illumination.

In order to achieve the above object, a planar illumination device according to the first aspect of the present invention includes a light guide plate, a plurality of light sources arranged in a row along the longitudinal direction of the side end surface of the light guide plate, Each of the planar lighting devices includes a mounting board on which each is mounted. The mounting board includes a base material and a conductive pattern formed on the base material, and a cover member is disposed on the conductive pattern. The conduction pattern is provided in a longitudinal direction corresponding to each pair of electrode terminals of the light source, and is connected to the plurality of pairs of lands to which the pair of electrode terminals are respectively connected. The light guide plate is disposed on the light source side boundary adjacent to the land side opposite to the land side that forms a pair with each land in the longitudinal direction of the mounting substrate in each land. Side A first lead portion extending from the corner formed by the boundary toward the light guide plate side to the lower side of the cover member, and the side on which the light guide plate is disposed on the side where the first lead portion is provided A second lead portion extending from the corner of the land on the opposite side to the light guide plate side to the lower side of the cover member, and a land-side boundary forming a pair in the land The corner formed by the boundary on the side opposite to the light guide plate is not connected to the leading portion extending from the boundary on the side opposite to the light guide plate to the side opposite to the light guide plate . The second lead portion extends substantially perpendicularly to the longitudinal direction of the mounting substrate .

  According to the first aspect of the present invention, the corner formed by the land-side boundary forming a pair in the land and the boundary opposite to the light guide plate side is guided from the boundary opposite to the light guide plate side. Since the drawer portion extending to the side opposite to the optical plate is not connected, high-precision self-alignment when mounting the light source on the mounting substrate is possible. Further, the lead-out portion connected to the land can suppress peeling of the conductive pattern and the light source from the mounting substrate. Therefore, it is possible to achieve high brightness and uniform illumination of the planar illumination device.

In the planar lighting device according to the second aspect of the present invention, in the first aspect of the present invention, the cover member includes a first cover member disposed on the light guide plate side of the light source, and the light guide plate side of the light source. comprises a second cover member which is disposed at a side opposite to the said first cover member is disposed on the first lead portion on the light guide plate side, the second cover member is the light guide plate disposed on the second lead portion on the opposite side of the.

In the planar lighting device according to the third aspect of the present invention, in the second aspect of the present invention, the first cover member and the second cover member are connected between the pair of lands.

In the planar lighting device according to the fourth aspect of the present invention, in any one of the first to third aspects of the present invention, one light source is driven and controlled independently of the other adjacent light sources.
According to the fourth aspect of the present invention, independent drive control is possible between adjacent light sources.

According to a fifth aspect of the present invention, there is provided the planar lighting device according to any one of the first to fourth aspects, wherein the mounting board is a flexible printed board.
According to the fifth aspect of the present invention, the space of the planar lighting device can be reduced.
In the planar illumination device according to the sixth aspect of the present invention, in any one of the first to fifth aspects of the present invention, no conduction pattern is formed from the land toward the adjacent light source.
According to a seventh aspect of the present invention, there is provided the planar lighting device according to any one of the first to fifth aspects, wherein the first lead-out portion is formed in a direction in which the plurality of light sources are arranged. Connected to the pattern.

  ADVANTAGE OF THE INVENTION According to this invention, the planar illuminating device which has high reliability and can implement | achieve high brightness | luminance and uniformity of illumination stably can be provided.

(a) is a top view which shows the planar illuminating device of embodiment which concerns on this invention, (b) is the A section enlarged view of (a). It is an enlarged view which shows the assembly | attachment of LED on the light-guide plate and FPC of embodiment. (a) is a top view which shows the surface of FPC of embodiment, (b) is a top view which shows the back surface of FPC of embodiment. It is the figure which expanded and showed an example of the conduction pattern of the part which mounts one LED. (a) is a top view which shows the light source part of the conventional sidelight type backlight, (b) is an example of the board | substrate (circuit board which mounts LED) in the light source part of the conventional sidelight type backlight. It is a top view which expands and shows.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
Fig.1 (a) is a top view which shows the planar illuminating device of embodiment based on this invention, FIG.1 (b) is the A section enlarged view of Fig.1 (a).
FIG. 2 is an enlarged view showing the assembly of the LED on the light guide plate and the FPC.
The planar illumination device S of the embodiment is a planar illumination device that performs illumination from the rear used for a backlight such as a liquid crystal panel.

The planar illumination device S is an illumination device called a sidelight type backlight in which an LED (Light Emitting Diode) 1 as a light source is disposed on the side of the light guide plate 2.
Specifically, the planar illumination device S is provided with a plurality of LEDs 1 (1r, 1g, 1b) mounted on the FPC 3 in contact with the side end surface 2s on the side of the light guide plate 2, and the light guide plate 2 is irradiated with light. The LEDs 1 are all white LEDs, and the LEDs 1r, LED1g, and LED1b are obtained by grouping white LEDs into three groups. That is, LED 1r is an LED belonging to the first group of white LEDs, LED 1g is an LED belonging to the second group of white LEDs, and LED 1b is an LED belonging to the third group of white LEDs.

  On the rear side of the light guide plate 2 (the back side of the paper in FIG. 1A), the light that deviates from the total reflection condition of the light guide plate 2 and leaks back is reflected to the front side (the front side of the paper surface in FIG. 1A). A sheet (not shown) is arranged. On the other hand, a diffusion sheet (not shown) for diffusing light, a prism sheet (not shown) for increasing luminance, and the like are disposed in front of the light guide plate 2 (on the front side in FIG. 1 (a)). .

  FIG. 3A is a plan view showing the front surface of the FPC of the embodiment, and FIG. 3B is a plan view showing the back surface of the FPC of the embodiment. In FIG. 3A, the electrode terminals dra, drb, dga, dgb, dba, dbb of the LED 1 are conductive patterns (r1, r2, h1a, h1b, h2a, h2b exposed from the opening 4k of the cover lay 4). , H3a, h3b), in order to clarify the positional relationship, black is used in all groups.

FIG. 4 is an enlarged view showing an example of a conduction pattern (around a pair of lands in part B in FIG. 3A) of a portion where one LED is mounted. Note that a second group of LEDs 1g is disposed in part B of FIG.
On the front and back surfaces of the FPC 3, wiring patterns p1, p2, p3, p4, lands r1, r2, and lead portions h1a, h1b, h2a, h2b, h3a, h3b (see FIG. 4), which are conductive patterns of a conductive foil such as copper Is formed by etching or the like. That is, in addition to the wiring patterns p1, p2, and p3, the lands r1 and r2 and the lead portions h1a and h1b, h2a, h2b, h3a, and h3b are conductive conductive patterns.

As shown in FIG. 3A and FIG. 4, the wiring patterns p1, p2, p3, and p4, which are the conductive patterns of the FPC 3, and the lead-out portions h1a, h1b, h2a, h2b, h3a, and h3b are adjacent to the LED1. The cover lay 4 is arranged in such a manner that the opposing lands r2 and r1 of the two pairs of lands r1 and r2 are integrally exposed from the opening 4k. 3A and 4, the cover lay 4 (opening 4k) is indicated by a two-dot chain line.
That is, the surface of the FPC 3 (see FIG. 3A) is covered with the cover lay 4 having the opening 4k. The coverlay 4 is an insulating material having heat resistance and adhesiveness.

Each pair of electrode terminals dra, drb, electrode terminals dga, dgb, and electrode terminals dba, dbb of the adjacent LEDs 1 (1r, 1g, 1b) are regions of the coverlay 4 between the corresponding lands r1, r2 and the openings 4k. It is fixed by soldering across the board and electrically connected. Thereby, each LED1 is mounted in FPC3.
For example, in the rightmost first group of LEDs 1r of the FPC 3 in FIG. 1 (a), as shown in FIG. 1 (b) and FIG. 3 (a), the electrode terminal dra passes through the opening 4k of the cover lay 4, The electrode terminal drb is soldered to the land r2 (see FIG. 4) through the opening 4k of the cover lay 4 while being soldered to the land r1 (see FIG. 4).

  Similarly, in the second group of LEDs 1g from the right of the FPC 3 in FIG. 1A, the electrode terminal dga passes through the opening 4k of the cover lay 4 as shown in FIG. 3A and FIG. The electrode terminal dgb is soldered to the land r2 through the opening 4k of the cover lay 4 while being soldered to the land r1.

  Similarly, in the third group of LEDs 1b from the right of the FPC 3 in FIG. 1A, the electrode terminal dba passes through the opening 4k of the cover lay 4 through the land r1 as shown in FIG. The electrode terminal dbb is soldered to the land r2 through the opening 4k of the cover lay 4. Other LEDs 1 are similarly mounted (mounted) on the FPC 3.

  As described above, the cover lay 4 is arranged between the lands r1 and r2 of the LED 1 (the place of the cover lay 4 between the openings 4k), but in order to realize a narrow pitch of the LEDs 1, as described below. The shape of the conduction pattern (r1, r2, h1a, h1b, h2a, h2b, h3a, h3b, p1 to p4) is formed.

Here, because of the structure (design), the backlight is assembled so that the LED 1 is abutted against (contacted with) the side end surface 2s of the light guide plate 2 as indicated by the white arrow α1 in FIG. The peel strength from the FPC 3, that is, the strength of fixing the LED 1 to the FPC 3 is very important.
In this abutting step, the wiring (conduction pattern) of the FPC 3 on the light guide plate 2 side (front) receives an external force so as to float from the FPC 3 (the base material 3b), while the wiring on the opposite side (back) of the light guide plate 2 ( Since an external force is applied so that the conductive pattern) is pressed by the FPC 3, the wiring on the light guide plate 2 side (front) is more easily peeled off from the base material 3b than the wiring on the opposite side (rear side) of the light guide plate 2.

<FPC3>
An FPC 3 that is a double-sided FPC shown in FIG. 3 is configured to mount 12 LEDs 1 that are white LEDs as shown in FIG. As described above, the 12 LEDs 1 are divided into three groups, the LED 1r belonging to the first group, the LED 1g belonging to the second group, and the LED 1b belonging to the third group. It is comprised from LED1 (1r, 1g, 1b). That is, twelve LEDs 1 are composed of four first group LEDs 1r, four second group LEDs 1g, and four third group LEDs 1b.

Then, the twelve LEDs 1 (1r, 1g, 1b) are arranged from one end (right end) to the other end (left end) of the FPC 3, from the first group LED 1r, the second group LED 1g, and the third group LED1b is made into one unit, and it arrange | positions so that four units may be repeated.
The LEDs 1 (1r, 1g, 1b) belonging to each group are connected in series as shown in FIG. That is, among the 12 LEDs 1, the first group of LEDs 1r are connected in series, the second group of LEDs 1g are connected in series, and the third group of LEDs 1b are connected in series. ing.

  Specifically, the FPC 3 shown in FIG. 3 has a base material 3b and conductive patterns (p1 to p4, h1a, h1b, h2a, h2b, h3a, h3b, r1, r2) formed on the base material 3b. The FPC 3 is provided with an LED mounting portion 3A on which the LED 1 is mounted, wiring patterns p1 to p4 for connection to the LED 1, and connection terminals st (see FIG. 3B) electrically connected thereto. Wiring part 3B.

On the front and back surfaces of the FPC 3, wiring patterns p1, p2, p3, and p4 for supplying current (voltage) to the LEDs 1 (1r, 1b, 1g) are lands r1, r2 to which the respective LEDs 1 are connected, and lead portions. Along with h1a, h1b, h2a, h2b, h3a, and h3b, it is formed by etching or the like.
The FPC 3 has through holes th for electrically connecting the wiring patterns p1 to p4 on the front surface shown in FIG. 3A and the wiring patterns p1 to p4 on the back surface shown in FIG. Yes.

  The pair of electrode terminals dra and drb of the first group of LEDs 1r are connected to the wiring pattern p1, and the pair of electrode terminals dga and dgb of the second group of LEDs 1g are connected to the wiring pattern p2. A pair of electrode terminals dba and dbb of the third group of LEDs 1b are connected to the wiring pattern p3. The wiring pattern p4 is a ground line.

  In other words, the LEDs 1r of the four first groups are connected in series via the wiring pattern p1 and the through hole th formed on the front and back surfaces of the FPC 3. In addition, the LEDs 1g of the four second groups are connected in series via a wiring pattern p2 and a through hole th formed on the front and back surfaces of the FPC 3. Similarly, the four LEDs 1b of the third group are connected in series via the wiring pattern p3 and the through hole th formed on the front and back surfaces of the FPC 3.

  As shown in FIG. 1, the LED 1 of one point light source has a group of LEDs different from the LED 1 of another adjacent point light source. That is, a second group of LEDs 1g is disposed adjacent to the first group of LEDs 1r, a third group of LEDs 1b is disposed adjacent to the second group of LEDs 1g, The first group of LEDs 1r is disposed adjacent to the first group of LEDs 1b.

In this way, drive control of the LED 1 of another group of point light sources adjacent to the LED 1 of the point light source can be performed independently of each other via the wiring pattern p (p1, p2, p3). That is, the LED 1r of the first group, the LED 1g of the second group, and the LED 1b of the third group are connected to each other via the wiring patterns p1 to p4 so that drive control can be performed independently of each other.
In the present embodiment, the case where drive control of three adjacent groups (three groups) of LEDs 1 (1r, 1g, 1b) can be performed independently of each other is illustrated, but two groups (two groups) or four groups (4 The wiring pattern may be formed so that the drive control of the above group) can be performed independently of each other.

<Conduction pattern>
Next, characteristic portions of the conduction pattern (p1 to p4, r1, r2, h1a, h1b, h2a, h2b, h3a, h3b) of the FPC 3 according to the present embodiment will be described with reference to FIG.
In FIG. 4, in order to clarify the positional relationship between the electrode terminals dga, dgb of the second group of LEDs 1g and the conduction patterns (p4, r1, r2, h1a, h1b, h2a, h2b, h3a, h3b), The L-shaped electrode terminals dga and dgb of the LEDs 1g of the second group are shown in black on the lands r1 and r2.

  As described above, each LED 1 (see FIG. 1) has a pair of electrode terminals dra, drb, dga, dgb, dba, dbb fixed to the rectangular lands r1, r2 shown in FIG. 4 by soldering. The

The conduction pattern formed on the FPC 3 has the following characteristics.
First, one of the lands r1 having a rectangular shape (indicated by a solid line and a two-dot chain line in FIG. 4) outside (the left side of the land r1 in FIG. 4), that is, the other in the X direction (longitudinal direction of the FPC 3) in FIG. The side of the third group of LEDs 1b (see FIG. 1A) adjacent to the left in FIG. 4 on the side opposite to the land r2 is the side where the light guide plate 2 is disposed (Y direction (short direction of the FPC 3)) A first lead portion h1a which is a wiring extending from the one corner (end portion) to the light guide plate 2 side is formed.

The first lead portion h1a is formed in a rectangular shape and connected to the wiring pattern p4.
A portion of the first lead portion h1a near the land r1 is exposed from the opening 4k (indicated by a two-dot chain line in FIG. 4) of the cover lay 4, and the other portion is covered with the cover lay 4. The tip of the first lead portion h1a is electrically connected to the wiring pattern p4.

  Also, one land in the outer side (right side of the land r2 in FIG. 4) outside the other land r2 (shown by a solid line and a two-dot chain line in FIG. 4), that is, in the X direction in FIG. 4 (longitudinal direction of the FPC 3). The side opposite to r1, that is, the side on which the light guide plate 2 on the side of the first group of LEDs 1r (see FIG. 1A) adjacent to the right in FIG. 4 is disposed (in the Y direction (short direction of the FPC 3)) A first lead portion h1b, which is a wiring extending from one corner (end portion) to the light guide plate 2 side, is formed.

  The first lead portion h1b has a rectangular shape. The first lead portion h1b is electrically connected to a second lead portion h2b described later, and is electrically connected to the wiring pattern p2 (see FIG. 3B) formed on the back surface side through the through hole th1. It is connected to the.

  Secondly, a second lead which is a wiring extending from one corner on the side where the light guide plate 2 is arranged to the inside of one land r1 (the other land r2 side in the X direction in FIG. 4) to the light guide plate 2 side. A portion h2a is formed.

  The second lead portion h2a is formed in a wide shape so as to protrude toward the light guide plate 2 side and the other land r2. It is formed in a wide shape up to a level at which a stripe-shaped gap s1 is formed between a pair of second lead portions h2b to be described later. The second lead portion h2a is covered with the cover lay 4 except for a portion (region) near the land r1 while the portion (region) near the land r1 is an opening of the cover lay 4. It is exposed from 4k (indicated by a two-dot chain line in FIG. 4).

  That is, by effectively utilizing the space inevitably formed between the pair of lands r1 and r2 by the structure of the electrode terminals dga and dgb of the second group of LEDs 1g, the second lead portion h2a of the conduction pattern is formed. ing. The second lead portion h2a is directly electrically connected to the wiring pattern p4.

Further, a second lead portion h2b which is a wiring extending from the one corner on the side where the light guide plate 2 is disposed inside the other land r2 (on the one land r1 side in the X direction in FIG. 4) to the light guide plate 2 side. Is formed.
The second lead portion h2b is formed in a wide shape so as to project toward the light guide plate 2 side and the other land r1. The second lead portion h2b is formed in a wide shape up to a level at which a stripe-shaped gap s1 is formed between the second lead portion h2a and the pair of second lead portions h2a.

The second lead portion h2b is covered with the cover lay 4 except for the portion (region) near the land r2, and the portion (region) near the land r2 is opened from the opening 4k of the cover lay 4. Exposed. That is, by effectively utilizing the space inevitably formed between the pair of lands r1 and r2 by the structure of the electrode terminals dga and dgb of the second group of LEDs 1g, the second lead portion h2b of the conduction pattern is formed. ing.
As described above, the second lead portion h2b is electrically connected to the wiring pattern p2 (see FIG. 3B) formed on the back surface side through the through hole th1.

  With the above configuration, in the second group of LEDs 1g, one electrode dga is connected to the wiring pattern p4 from the first and second lead portions h1a and h2a, and the other electrode dgb is connected to the first and second electrodes. The two lead portions h1b and h2b are connected to the wiring pattern p2 (see FIG. 3B) on the back surface through the through hole th1. Similarly, the other LEDs 1g in the second group are connected in series to the wiring pattern p2.

Similarly, the first group of LEDs 1r and the third group of LEDs 1b are soldered to a corresponding pair of lands r1 and r2, and the first group of LEDs 1r are connected in series to the wiring pattern p1, and the first Three groups of LEDs 1b are connected in series to the wiring pattern p3.
Thereby, LED1 of the same group of 4 units is connected in series independently with LED1 of another group.

As described above, four units of the first group of LEDs 1r are independent of the other second group of LEDs 1g and the third group of LEDs 1b through the wiring pattern p1, as shown in FIG. Connected in series.
In addition, as shown in FIG. 3, four units of the second group of LEDs 1g are independently connected in series with the other first group of LEDs 1r and the third group of LEDs 1b via the wiring pattern p2. Has been.

  Similarly, as shown in FIG. 3, four units of the third group of LEDs 1b are independent of the first group of LEDs 1r and the second group of LEDs 1g via the wiring pattern p3. Connected in series.

Third, as shown in FIG. 4, the wiring extends from one corner on the opposite side to the side where the light guide plate 2 is disposed in the Y direction of one land r <b> 1 toward the outer side to the opposite side of the light guide plate 2. A third lead portion h3a is formed. The third lead portion h3a extends so that its tip is covered with the cover lay 4, and its root portion (side connected to the land r1) is exposed from the opening 4k of the cover lay 4.
The width of the third lead portion h3a is formed wider than the width of the first lead portion h1a formed so as to be connected to the land r1.

  Similarly, a third lead portion h3b that is a wiring extending to the opposite side of the light guide plate 2 is formed from one corner opposite to the side where the light guide plate 2 is disposed in the Y direction of the other land r2. Has been. The third lead portion h3b extends so that its tip is covered with the cover lay 4, and its root portion (side connected to the land r2) is exposed from the opening 4k of the cover lay 4.

The width of the third lead portion h3b is formed wider than the width of the first lead portion h1b formed so as to be connected to the land r2.
FIG. 4 illustrates the case where the tips of the third lead portions h3a and h3b are electrically opened. However, some of the third lead portions h3a and h3b shown in FIG. As described above, the tip may be bypassed and electrically connected to another conduction pattern.

In the present embodiment, the third lead portions h3a and h3b are formed wider than the first lead portions h1a and h1b, respectively. However, the areas of the third lead portions h3a and h3b are respectively set to the first lead portions h3a and h3b. You may comprise larger than the drawer | drawing-out part h1a and h1b.
As described above, the electrode terminals dga and dgb of the second group of LEDs 1g are fixed to the lands r1 and r2 of the FCP3 by soldering, so that the second group of LEDs 1g is attached to the FCP3.
Similarly, the electrode terminals dra and drb of the first group of LEDs 1r and the electrode terminals dba and dbb of the third group of LEDs 1b are also fixed to the corresponding pair of lands r1 and r2.

  At this time, of the external lines of the pair of lands r1 and r2, the lands of the portions where the first lead portions h1a and h1b, the second lead portions h2a and h2b, and the third lead portions h3a and h3b are not connected. When mounting the LED 1 (1r, 1g, 1b) on the lines i1, i2, i3 (indicated by solid lines in FIG. 4) of the r1 and the lines i4, i5, i6 (indicated by solid lines in FIG. 4) of the land r2 The self-alignment reference for the two-axis directions (X and Y directions) can be used. Specifically, for the X direction, the lines i1 and i4 orthogonal to the X direction are the reference, and for the Y direction, the lines i2, i3, i5, and i6 orthogonal to the Y direction are the reference. .

By forming the conductive pattern having the above configuration, the following effects can be obtained.
As a first point, the leading ends of the first lead portions h1a and h1b and the third lead portions h3a and h3b and many portions of the second lead portions h2a and h2b formed in a wide or large area are covered by the coverlay 4. The first, second, and third lead portions h1a, h1b, h2a, h2b, h3a, h3b, the wiring patterns p1 to p4, and the lands r1 and r2 of the conductive pattern are peeled off from the FCP3. The peel strength of the LED 1 from the FCP 3 is improved. As a result, it is possible to increase the mounting density of the LEDs 1 to a level at which the coverlay 4 cannot be disposed between the adjacent LEDs 1. Actually, as shown in FIG. 3A, the opening 4k of the cover lay 4 is arranged between the adjacent LEDs 1.

  As a second point, the two lead portions extending from the two corners of the lands r1 and r2 on the light guide plate 2 side (the upper side in FIG. 4) to the lower part of the cover lay 4 forward, that is, the first lead portion h1a. , H1b and the second lead portions h2a, h2b, the FPC 3 (of the conductive pattern) of the wiring (conduction pattern) in the step (see FIG. 2) of abutting the LED 1 in the step of assembling the planar lighting device S to the light guide plate 2 Peeling from the front portion of the base material 3b can be effectively suppressed. That is, by forming the conductive pattern including the lands r1 and r2 as shown in FIG. 4, the peeling strength of the LED 1 (fixing strength of the LED 1 to the FPC 3) is secured, and the strength is secured.

The third point is that the width of the third lead portions h3a and h3b is wider or larger than the width of the first lead portions h1a and h1b, thereby increasing the peeling strength of the wiring (conduction pattern) on the rear side. Can be bigger.
As a result, the light guide plate 2 side and the anti-light guide plate 2 side (upper and lower surfaces of FIG. 4) due to the absence of portions corresponding to the second lead portions h2a and h2b on the side opposite to the light guide plate 2 (lower side in FIG. 4). (Fixed strength in the direction) is reduced, and it becomes possible to compensate for insufficient peeling strength on the rear side on the side opposite to the light guide plate 2 (the lower side in FIG. 4). This is an effective means when the peeling strength of the conductive pattern on the side opposite to the light guide plate 2 becomes a problem.

  As a fourth point, the first lead portions h1a and h1b, the second lead portions h2a and h2b, and the third lead portions h3a and h3b of the pair of lands r1 and r2 shown in FIG. 4 are connected. The parts (lines i1 to i6) not shown (shown by solid lines in FIG. 4) are used as a reference for self-alignment with respect to the biaxial direction (X and Y directions in FIG. 4) when the LED 1 is mounted on the FPC 3. be able to. As described above, i1 and i4 are the reference for the X direction, and i2, i3, i5, and i6 are the reference for the Y direction. Thereby, it is possible to ensure the positional accuracy at the time of mounting LED1.

  From the first point to the fourth point, the cover lay 4 is not disposed between the lands r1 and r2 on which the LED 1 is mounted, that is, between the adjacent LEDs 1 (the opening 4k of the cover lay 4 is disposed), and the land r1, By devising the shape of r2, it is possible to realize a narrow pitch arrangement of the LEDs 1 while ensuring the peel strength of the LEDs 1 from the FPC 3. Therefore, an LED mounting land pattern for narrowing the LED pitch can be formed.

Thereby, since many LED1 can be arrange | positioned in the limited space, the planar illuminating device S with high brightness | luminance is realizable.
Moreover, since disconnection of the conductive pattern is prevented, a highly reliable planar illumination device S can be realized.
Moreover, since the self-alignment at the time of LED mounting can be performed with high precision, the planar illumination device S that can stably provide high luminance and uniform illumination can be realized.

<< Other Embodiments >>
In the above-described embodiment, the point light source LED 1 is exemplified, but a light source having a shape other than the point light source such as a linear light source or a planar light source may be used as long as the present invention is applicable.
In the above-described embodiment, the case where the stripe-shaped gap s1 is provided between the second lead portions h2a and h2b is illustrated. However, the gap does not necessarily have to be a stripe shape. However, it is more preferable to form the gap between the second lead portions h2a and h2b narrow because the second lead portions h2a and h2b can be formed with a large area.

In the embodiment, the FPC 3 is illustrated as an example of the light source mounting substrate. However, a substrate other than the FPC 3 may be applied as long as the present invention is applicable. However, the FPC 3 is suitable for the planar lighting device S in a narrow space.
Moreover, although the said embodiment demonstrated and demonstrated the case where LED1 was white LED, you may apply LED of another different color as LED1.

  While embodiments of the present invention have been described above, the description is intended to be exemplary. Accordingly, various modifications and changes can be made within the scope of the present invention. That is, the present invention can be arbitrarily changed as appropriate without departing from the spirit of the invention.

1 LED (light source)
2 Light guide plate 3 FPC (mounting board)
3b Base material 4 Cover lay (cover member, first cover member, second cover member)
p1, p2, p3, p4 Wiring pattern (conduction pattern)
ra, rb land (conduction pattern)
h1a, h1b First drawer part (drawer part, conduction pattern)
h3a, h3b Second drawer part (drawer part, conduction pattern)
dr, dg, db electrode terminal S planar illumination device

Claims (7)

A planar illumination device comprising a light guide plate, a plurality of light sources arranged in a line along the longitudinal direction of the side end face of the light guide plate, and a mounting substrate on which each of the light sources is mounted,
The mounting substrate has a base material and a conductive pattern formed on the base material, and a cover member is disposed on the conductive pattern,
The conductive pattern is provided in the longitudinal direction corresponding to each pair of electrode terminals of the light source, and a plurality of pairs of lands to which the pair of electrode terminals are connected, respectively, and leads connected to the pair of lands. Including
The drawer is
A corner portion formed by a boundary on the light source side adjacent to the land side opposite to the land side that forms a pair with each land and a boundary on the side where the light guide plate is disposed in the longitudinal direction of the mounting substrate in each land. A first lead portion extending from the light guide plate side to the lower side of the cover member, and a side of the land opposite to the side where the light guide plate is disposed on the side where the first lead portion is provided. A second lead portion extending from the corner toward the opposite side of the light guide plate to the lower side of the cover member,
A corner formed by a land-side boundary forming a pair in the land and a boundary opposite to the light guide plate side extends from the boundary opposite to the light guide plate side to the opposite side of the light guide plate. The drawer is not connected ,
The planar lighting device, wherein the first and second lead portions extend substantially perpendicular to a longitudinal direction of the mounting substrate . It said cover member includes a first cover member disposed on the light guide plate of the light source, and the light guide plate of the light source comprises a second cover member disposed on the opposite side, the first the cover member is disposed on the first lead portion on the light guide plate side, said second cover member from said light guide plate and being disposed on said second extraction portion on the opposite side The planar illumination device according to claim 1. The planar illumination device according to claim 2, wherein the first cover member and the second cover member are connected between the pair of lands. 4. The planar illumination device according to claim 1, wherein one of the light sources is driven and controlled independently of the other adjacent light sources. 5. The planar lighting device according to any one of claims 1 to 4, wherein the mounting board is a flexible printed board. No conduction pattern is formed from the land toward the adjacent light source.
The planar illumination device according to any one of claims 1 to 5, wherein The first lead portion is connected to a conduction pattern formed in a direction in which the plurality of light sources are arranged.
The planar illumination device according to any one of claims 1 to 5, wherein

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