JP5836812B2 - Linear light source device, surface light emitting device, and liquid crystal display device - Google Patents

Description

  The present invention relates to a linear light source device that emits linear light from a plurality of light emitting elements arranged in a longitudinal direction on a long substrate, a surface light emitting device, and a liquid crystal display device.

  The light source device includes a light emitting element, a wiring pattern for supplying power to the light emitting element, and an optical member such as a light guide plate that irradiates light from the light emitting element in a desired direction. Some light source devices include a plurality of light emitting elements, a linear one, and the like. In general, the light source device is required to emit uniform light. Conventional light source devices are disclosed in Patent Documents 1 to 3, for example.

(Patent Document 1)
FIG. 15 shows an outline of the surface light source unit described in Patent Document 1. FIG. 15 (a) is a plan view, and FIG. 15 (b) is a cross-sectional view taken along line CC in FIG. 15 (a). It is sectional drawing in a 'line, (c) of the figure is sectional drawing in the DD' line in (a) of the figure. As shown in the figure, the surface light source unit 1000 includes a light guide plate 1001 and a light emitting unit 1002, and the light emitting unit 1002 is an LED mounting in which a plurality of chip-shaped LEDs (light emitting diodes) 1003 as light emitting elements are multilayer wiring structures. It is mounted on the circuit board 1004.

  The plurality of LEDs 1003 are connected in series in each of the two groups 1010 and 1011. Thereby, a drive voltage can be made low compared with the structure which connects all LED1003 in series. Furthermore, it is possible to secure the necessary light quantity simply by increasing the number of groups.

  The LEDs 1003 are arranged so that the LEDs 1003 belonging to the first and second groups 1010 and 1011 are adjacent to each other. Thereby, when any of the LEDs 1003 is broken and disconnected, the group to which the LED 1003 belongs is turned off, but since the other groups are turned on, the light emission can be continued.

(Patent Documents 2 and 3)
FIG. 16 is a perspective view showing an outline of the linear light source device described in Patent Documents 2 and 3. In the illustrated linear light source device 1100, a plurality of light emitting elements 1101 are arranged at intervals from each other along the longitudinal direction of a long substrate 1102 on which an electrode pattern is formed, and covers each light emitting element 1101. As described above, a sealing member 1103 made of a translucent resin is formed. Further, positive and negative connection terminals 1106 and 1107 for energizing the light emitting element 1101 are formed at both ends of the substrate 1102, respectively. The illustrated linear light source device 1100 is provided in the vicinity of the side surface of the light guide plate in the same manner as the light emitting unit 1002 shown in FIG.

  As shown in FIG. 16, the sealing member 1103 includes a planar portion in which first and second recesses 1104 and 1105 having a V-shaped cross section along the longitudinal direction of the substrate 1102 are substantially parallel to the upper surface of the substrate 1102. 1108 are alternately connected to each other. The first recess 1104 is formed between the adjacent light emitting elements 1101 and 1101, and the second recess 1105 is formed immediately above the light emitting element 1101.

  According to the above structure, part of the light from the light emitting element 1101 is reflected by the second recess 1105 and guided in the longitudinal direction of the substrate 1102. Accordingly, it is possible to suppress the luminance that tends to be excessively high immediately above the light emitting element 1101. Further, part of the light guided in the longitudinal direction of the substrate 1102 is refracted by the first recess 1104 and irradiated to the outside. Accordingly, it is possible to increase the luminance that tends to decrease in the intermediate portion between the adjacent light emitting elements 1101 and 1101. As a result, even when light is emitted with high luminance, uneven luminance and bright lines can be suppressed.

  Further, the sealing member 1103 includes a fluorescent portion (not shown) mixed with phosphors in the vicinity of the light emitting element 1101. Thereby, even when a desired color is emitted, chromaticity unevenness can be suppressed.

Japanese Unexamined Patent Publication No. 2004-233809 (published on August 19, 2004) JP 2009-021221 A (released on January 29, 2009) JP 2009-260174 A (published on November 05, 2009)

  In the linear light source device 1100 described in Patent Documents 2 and 3, all the light emitting elements 1101 are connected in series by electrode patterns on the substrate 1102. Therefore, in order to further improve the luminance, when the number of the light emitting elements 1101 is increased, it is necessary to increase the voltage applied between the positive and negative connection terminals 1106 and 1107.

  For example, it is assumed that the driving voltage per light emitting element 1101 is 3.2 V, and the maximum voltage that can be applied to the linear light source device 1100 is 24 V. In this case, when 22 light emitting elements 1101 are connected in series, it is necessary to apply a voltage of 3.2 V × 22 = 70.4 V, and the applied voltage is insufficient. For this reason, in the linear light source device 1100 described in Patent Literatures 2 and 3, it is difficult to increase the luminance by increasing the number of the light emitting elements 1101.

  On the other hand, in the case of the surface light source unit 1000 described in Patent Document 1, since the LEDs 1003 are divided into two groups, 3.2 V × 22/2 = 35.2 V is sufficient. Therefore, if the LEDs 1003 are divided into three or more groups, the maximum value of the voltage that can be applied is not exceeded.

  However, in the case of the surface light source unit 1000 described in Patent Document 1, since the LEDs 1003 and the wiring patterns are provided on the substrate, it is necessary to increase the number of wiring patterns in order to increase the number of the groups. As a result, it is necessary to increase the width of the substrate. As a result, the light source device is increased in size.

  The present invention has been made in view of the above problems, and its purpose is to provide a linear light source device that can increase the number of light-emitting elements and can suppress an increase in the scale of the device. It is to provide.

  The linear light source device according to the present invention is a linear light source device that irradiates linear light from a plurality of light emitting elements arranged in a longitudinal direction on a long substrate. And a wiring pattern for connecting the plurality of light emitting elements in series, and the light emitting elements and the wiring pattern are divided into a plurality of groups. Are connected in series via the wiring pattern, and power is supplied to each group, and the wiring pattern of each group is formed on the back surface of the substrate.

  According to the above configuration, the light emitting elements and the wiring patterns are divided into a plurality of groups. In each group, the light emitting elements are connected in series via the wiring patterns, and power is supplied to each group. It has become. As a result, the driving voltage can be lowered as compared with the configuration in which all the light emitting elements are connected in series, so that the number of light emitting elements can be increased, and as a result, the luminance can be increased.

  Moreover, since the wiring patterns of each group are formed on the back surface of the substrate, an increase in the width of the substrate can be suppressed as compared with the conventional configuration formed on the top surface of the substrate. As a result, an increase in the scale of the apparatus can be suppressed.

In the linear light source device according to the present invention, it is preferable that the light emitting elements of each group are alternately arranged. In this case, when one of the groups is disconnected due to a failure or the like, the light emitting elements belonging to the group cannot emit light, but the other groups can emit light. Thereby, the emission of light can be continued. Further, the light emitting elements adjacent to the light emitting elements that are unable to emit light belong to the other group and can emit light. Therefore, a decrease in luminance due to the absence of light from the light emitting element that has become unable to emit light can be suppressed by the light from the adjacent light emitting elements, and as a result, luminance unevenness can be suppressed.
The linear light source device according to the present invention further includes a through hole for electrically connecting the wiring patterns on the front surface and the back surface of the substrate, and the through hole is provided between the light emitting elements. The through hole for connecting one group of wiring patterns and the through hole for connecting another group of wiring patterns are provided at different positions in the short direction of the substrate. Is preferred. In this case, it is possible to reduce the size of the substrate in the short direction as compared with the conventional case, and as a result, it is possible to reduce the size of the linear light source device.

  The linear light source device according to the present invention further includes a light-transmitting sealing member that seals the plurality of light-emitting elements, and the sealing member is provided between the adjacent light-emitting elements. A first recess that bends light guided in the sealing member and guides part or all of the light to the outside, and light irradiated from the light emitting element in the normal direction of the upper surface of the substrate It is preferable to include a second recess that bends and guides part or all of the light into the sealing member.

  In this case, part or all of the light from the light emitting element is guided into the sealing member by the second recess. Accordingly, it is possible to suppress luminance that is directly emitted from the light emitting element and tends to be high. In addition, part or all of the light guided into the sealing member is irradiated to the outside by the first recess. Accordingly, it is possible to increase the luminance that tends to decrease between adjacent light emitting elements. As a result, even when light is emitted with high luminance, uneven luminance and bright lines can be suppressed. Further, when the light emitting elements of each group are alternately arranged, the luminance unevenness can be further suppressed.

  In addition, it is preferable that the 1st recessed part of the said sealing member totally reflects the light guided in the said longitudinal direction within the said sealing member. In this case, since it can prevent that the said light is irradiated from the longitudinal direction edge part of the said sealing member, the brightness | luminance from the said linear light source device can be increased.

  Moreover, it is preferable that the 2nd recessed part of the said sealing member reflects all the lights irradiated from the said light emitting element to the normal line direction of the said board | substrate upper surface. In this case, the high luminance light from the light emitting element can be prevented from being directly irradiated to the outside, and thus the luminance unevenness can be further suppressed.

  In addition, as an example of the shape of the 1st recessed part of the said sealing member, and a 2nd recessed part, the shape of the cross section along the longitudinal direction of the said board | substrate is mentioned.

  In the linear light source device according to the present invention, it is preferable that the sealing member includes a fluorescent material and includes a fluorescent part that covers each of the light emitting elements. In this case, chromaticity unevenness can be suppressed even when a desired color is emitted.

  In the linear light source device according to the present invention, one or a plurality of additional substrates are stacked on the lower surface of the substrate, and an external connection terminal that supplies power to the light emitting elements of each group includes the substrate and the additional substrate. The external connection terminal may be provided at one end of the substrate and the additional substrate using an additional wiring pattern formed on the additional substrate.

  In this case, in the connection destination device to which the linear light source device is connected, when the external connection terminals for supplying power are gathered, it is preferable that the wiring does not need to be routed. The external connection terminals may be collected on the upper surface of the substrate or may be collected on the lower surface of the additional substrate.

In the linear light source device according to the present invention, it is preferable that the wiring patterns of the respective groups are further formed on the upper surface of the substrate. In this case, since the wiring pattern functions as a reflector, the luminance can be increased.
In the linear light source device according to the present invention, each of the light emitting element and the wiring pattern group includes two external connection terminals, and the light emission included in the same group between the two external connection terminals. It is preferable that the element is arranged.

  In addition, if it is a surface light-emitting device provided with the linear light source device of the said structure and the light-guide plate for radiate | emitting the light linearly incident from this linear light source device with planar light, it is the same as that of the above-mentioned There is an effect. Further, the same effects as described above can be obtained as long as the liquid crystal display device outputs a display by including the surface light emitting device having the above-described configuration and a liquid crystal panel that modulates light from the surface light emitting device.

  As described above, in the linear light source device according to the present invention, power is supplied to each light emitting element connected in series via the wiring pattern in each group, so that the drive voltage can be lowered and the number of light emitting elements can be reduced. In addition to the effect that the wiring pattern can be increased, the wiring patterns of each group are formed on the back surface of the substrate, so that an increase in the width of the substrate can be suppressed. As a result, there is an effect of suppressing an increase in the scale of the apparatus.

It is a perspective view which shows the outline | summary of the linear light source device which is one Embodiment of this invention. It is a side view which shows the outline | summary of the said linear light source device. It is a perspective view which shows the dicing process in the manufacturing method of the said linear light source device. It is a front view which shows typically the electrical connection form of the light emitting element in the said linear light source device. It is the top view and bottom view which show the wiring pattern of the said linear light source device. It is a circuit diagram of the said linear light source device and its modification. It is sectional drawing which shows the state which mounted the said linear light source device in the mounting board | substrate. It is a front view which shows typically advancing of the light in the 1st recessed part vicinity of the sealing member in the said linear light source device. It is a front view which shows typically advancing of the light in the 2nd recessed part vicinity of the said sealing member. It is a graph which shows the profile of the luminous intensity in the said linear light source device. The front view which shows typically the structure of the linear light source device which is another embodiment of this invention, the figure which expands and shows a part of this structure, and expands and shows a part of modification of the said structure Figure. The front view which shows typically the structure of the linear light source device which is another embodiment of this invention, the figure which expands and shows a part of this structure, and the part of the modification of the said structure is expanded FIG. It is a front view which shows typically the structure of the linear light source device which is another embodiment of this invention. It is the top view which shows the wiring pattern of the linear light source device which is other embodiment of this invention, and the front view which shows typically the structure of the said linear light source device. It is the top view and sectional drawing which show the outline | summary of the conventional surface light source unit. It is a perspective view which shows the outline | summary of the conventional linear light source device. It is a graph which shows the profile of the luminous intensity in the conventional surface light source unit.

[Embodiment 1]
An embodiment of the present invention will be described with reference to FIGS. 1 and 2 are a perspective view and a side view showing an outline of a linear light source device 11 according to the present embodiment. As shown in FIGS. 1 and 2, the linear light source device 11 according to the present embodiment includes a printed circuit board 12, a plurality of light emitting elements 13, a sealing member 14, and reflection sheets 15 and 16. In FIG. 1, the reflective sheets 15 and 16 shown in FIG. 2 are omitted so that the structure of the linear light source device 11 can be easily understood.

(Outline of the linear light source device 11)
Although the linear light source device 11 of this embodiment is suitable as a linear light source of a backlight of a liquid crystal display device, it is not limited to this.

  As shown in FIG. 1, a plurality of light emitting elements 13 are arranged in a line at equal intervals along the longitudinal direction of the printed circuit board 12 on the upper surface of the long printed circuit board 12 to cover the plurality of light emitting elements 13. A translucent sealing member 14 is formed. The electrical connection form of the light emitting element 13 will be described later.

  As shown in FIG. 2, a reflective sheet 15 is attached to the front surface of the printed circuit board 12 and the sealing member 14, and a reflective sheet 16 is attached to the rear surface. Thereby, the light emitted from the light emitting element 13 is transmitted through the sealing member 14, and part of the light is reflected by the reflection sheets 15 and 16 and is irradiated to the outside. Accordingly, the linear light source device 11 functions as a linear light source that emits light in a direction perpendicular to the printed circuit board 12.

  Further, as shown in FIG. 1, the sealing member 14 has first and second recesses 20 and 21 having a V-shaped cross section along the longitudinal direction of the printed circuit board 12 on the upper surface of the printed circuit board 12. The parallel plane portions 22 are alternately connected. The first recess 20 is formed between the adjacent light emitting elements 13 and 13, and the second recess 21 is formed immediately above the light emitting element 13.

  As a result, the sealing member 14 formed between the adjacent light emitting elements 13 and 13 includes a bottom portion of the first recess 20 and has a substantially symmetric shape with respect to a plane whose normal is the longitudinal direction. Yes. Note that the end portions 23 and 23 of the sealing member 14 have inclined surfaces that spread outward toward the printed circuit board 12.

  According to the above configuration, the light from the light emitting element 13 is reflected by the second recess 21 and guided in the longitudinal direction of the printed circuit board 12. Therefore, it is possible to suppress the luminance that tends to be excessively high immediately above the light emitting element 13. Further, the light guided in the longitudinal direction of the printed circuit board 12 is refracted by the first concave portion 20 and is irradiated to the outside. Accordingly, it is possible to increase the luminance that tends to be low in the intermediate portion between the adjacent light emitting elements 13 and 13. As a result, even when light is emitted with high luminance, uneven luminance and bright lines can be suppressed.

  Further, the sealing member 14 has a fluorescent part 24 mixed with phosphors, and the fluorescent part 24 is formed so as to cover the light emitting element 13 in the vicinity of each light emitting element 13. Even when a desired color is emitted by the fluorescent portion 24, chromaticity unevenness can be suppressed.

  An example of the light emitting element 13 is an LED using a GaN compound semiconductor. The light-emitting element 13 is formed by laminating an n-type layer and a p-type layer on a transparent sapphire substrate, forming an n-type electrode or a p-type electrode on each upper surface of the n-type layer and the p-type layer, Is die-bonded to the wiring pattern of the printed circuit board 12 with a wire.

  Further, the sealing member 14 is formed of a translucent resin such as silicone. In addition, the fluorescent part 24 of the sealing member 14 is formed by dispersing the fluorescent material in the translucent resin.

(Manufacturing method of the linear light source device 11)
Next, a method for manufacturing the linear light source device 11 having the above configuration will be described. FIG. 3 is a perspective view showing a dicing step in the manufacturing method. First, a plurality of light-emitting elements 13 are mounted in a matrix on a plate-like printed circuit board 100, and a fluorescent material in which a phosphor is dispersed in a light-transmitting resin is applied to each light-emitting element 13. Thereby, the fluorescent member which coat | covers each light emitting element 13 is formed.

  Next, a translucent resin is formed in a region surrounded by the printed board 100, the fluorescent member, and a molding die in which two V-shaped grooves are formed along the rows of the light emitting elements 13. Inject and cure. Thereby, a plate-shaped sealing member 101 having two types of V-shaped grooves 102 and 103 is formed. The first groove 102 is formed between the adjacent rows, and the second groove 103 is formed immediately above the row. Thereby, the plate-like member 110 as shown in FIG. 3 is completed.

  Next, as shown in FIG. 3, dicing is performed on the plate-like member 110 in a direction perpendicular to the row using a dicing blade 120. Thereby, the plate-shaped printed circuit board 100, the fluorescent member, and the plate-shaped sealing member 101 are respectively the long printed circuit board 12, the fluorescent portion 24, and the long sealing member shown in FIG. 14, a long member as shown in the figure is generated. And the linear light source device 11 is completed by providing the reflective sheets 15 and 16 in the front surface and rear surface of the elongate member of illustration.

(Details of the linear light source device 11)
Next, an electrical connection form in the linear light source device 11 of the present embodiment will be described. FIG. 4 is a front view schematically showing the electrical connection form, and FIGS. 5A and 5B are a plan view and a bottom view respectively showing the electrical connection form. FIG.

  In the linear light source device 11 of the present embodiment, an anode external connection terminal 51 is connected to one end of a configuration in which a plurality of light emitting elements 13 are connected in series via a wiring pattern and a through hole, and the cathode is connected to the other end. An external connection terminal 52 is connected. Furthermore, in the present embodiment, the external connection terminals 51 and 52, the light emitting element 13, the wiring patterns 31 and 32, and the through hole 41 are divided into two groups. In the following, a member a belonging to the first group is denoted by a suffix a, and a member belonging to the second group is denoted by a suffix b.

  As shown in FIGS. 4 and 5, the printed circuit board 12 has the first group of light emitting elements 13 a and the second group of light emitting elements 13 b arranged alternately. In the following, in the printed circuit board 12, the surface on which the light emitting elements 13a and 13b are die-bonded is referred to as “front surface”, and the opposite surface is referred to as “back surface”.

  In the first group, the plurality of light emitting elements 13a include a wiring pattern 31a provided on the surface of the printed circuit board 12 between the external connection terminal 51a on the anode side and the external connection terminal 52a on the cathode side, and the back surface of the printed circuit board 12. Are connected in series via a wiring pattern 32a provided on the front surface and through-holes 41a for electrically connecting the wiring patterns 31a and 32a on the front and back surfaces.

  On the other hand, in the second group, the plurality of light emitting elements 13b include a wiring pattern 31b provided on the surface of the printed board 12 between the anode side external connection terminal 51b and the cathode side external connection terminal 52b, and the printed board 12. Are connected in series via a wiring pattern 32b provided on the back surface of the wiring pattern and through-holes 41b for electrically connecting the wiring patterns 31b and 32b on the front surface and the back surface.

  Also, as shown in FIG. 5, a single-layer double-sided board is used as the printed circuit board 12, and alternate wiring of the first group and second group wiring patterns 32a and 32b is formed on the back surface thereof.

  According to the above configuration, the five light emitting elements 13a belonging to the first group are connected in series, and the five light emitting elements 13b belonging to the second group are connected in series. Thereby, a drive voltage can be made low compared with the structure by which all the light emitting elements 13 were connected in series. In addition, the necessary amount of light can be secured simply by increasing the number of groups.

  Further, the light emitting element 13a and the light emitting element 13b are arranged so as to be adjacent to each other. Thereby, for example, even if the light emitting element 13a belonging to the first group is broken and becomes a disconnected state, the light emitting element 13a belonging to the group cannot be turned on, but the light emitting element 13b belonging to the second group can be turned on. The emission can be continued.

  Further, since the printed board 12 is not a multilayer board but a single-sided double-sided board, an inexpensive linear light source device 11 can be provided. Further, since the external connection terminals 51a · b and 52a · b are provided at both ends of the printed circuit board 12, a heat dissipation circuit can be formed on the left and right sides of the printed circuit board.

  In the embodiment, the width of the printed circuit board 12 is 0.4 mm. As shown in FIG. 5, the center of the first group of through holes 41 a is set at a position shifted forward by 100 μm from the center of the short side direction (width direction) of the printed circuit board 12. On the other hand, the center of the through hole 41b of the second group is set at a position shifted 100 μm backward from the center of the printed circuit board 12 in the short direction.

  Further, as shown in FIG. 5, on the surface of the printed circuit board 12, a wiring pattern 31a electrically connected to the first group of through holes 41a and a wiring pattern 31b electrically connected to the second group of through holes 41b. An interval of 100 μm is provided between them to form an alternate wiring. Further, on the back surface of the printed circuit board 12, a second group wiring pattern 32b having a width of 80 μm is formed beside the first group through-hole 41a, and the second group light emitting elements 13b are connected in series. Further, a first group wiring pattern 32a having a width of 80 μm is formed beside the second group through-hole 41b, and the light emitting elements 13a of the first group are connected in series.

  As described above, the positions of the through holes 41 a and b that connect the wiring patterns 31 a and b on the front surface and the wiring patterns 32 a and 32 b on the lower surface of the printed circuit board 12 from the center in the short direction of the linear light source device 11. It is arranged at a position shifted in the front-rear direction. In this way, the linear light source device 11 using a single-sided double-sided board as the printed board 12 is obtained. Thereby, compared with the structure of patent document 1, the size of the width direction of a board | substrate can be made small. As a result, the linear light source device 11 can be reduced in size.

  FIG. 6 is a circuit diagram of the linear light source device 11 of this embodiment and a modification thereof. In this embodiment, as shown to (a) of the figure, it is a 4 terminal structure which consists of four external connection terminals 51a * b and 52a * b. However, in this configuration, as shown in FIG. 4B, the external connection terminals 51a and 51b on the anode side of the first group and the second group are connected, and the external side of the first group and the second group on the cathode side is connected. A two-terminal structure including two external connection terminals 51 and 52 may be formed by connecting the connection terminals 52a and 52b.

  4 and 5, the first group of anode-side external connection terminals 51a and the second group of cathode-side external connection terminals 52b, which are located at both ends of the printed circuit board 12, are printed It is formed on both the front surface and the back surface of the substrate 12. This is to prevent the linear light source device 11 from floating when the linear light source device 11 is mounted on another mounting board by soldering.

  FIG. 7 is a cross-sectional view showing a state in which the linear light source device 11 is mounted on a mounting substrate 60 such as a flexible substrate. As shown in the drawing, the linear light source device 11 has the external connection terminals 51 a and 52 a and 52 a and b (or the external connection terminals 51) in a state where a cut surface (front surface or rear surface) by dicing is in contact with the upper surface of the mounting substrate 60. 52) and the terminals (not shown) of the mounting substrate 60 are connected by the solder 61. At this time, since the external connection terminals 51a and 52b described above are provided on both the front and back surfaces of the printed circuit board 12, both the front and back surfaces of the linear light source device 11 are fixed to the mounting substrate 60 by the solder 61. As a result, the floating can be suppressed.

  In the circuit shown in FIG. 6B, a single-sided structure in which the external connection terminals 51 and 52 are formed on the front surface or the back surface of the printed circuit board 12 may be used. According to the above structure, since the formation surface of the terminal is biased to one surface, there is a concern about the floating of the linear light source device 11, but there is an advantage that the mounting process can be reduced. Moreover, as shown in FIG.6 (c), it is good also as a structure which reversed the polarity of the light emitting element 13b from the circuit shown to (a) of the figure.

(Effect 1 of the linear light source device 11)
In the linear light source device 11, since the light emitting element 13 is not present at the intermediate position of the light emitting element 13, the light emission intensity is likely to be lower than that in the vicinity of the light emitting element 13. This causes luminance unevenness and color unevenness.

(Effect of the first recess 20)
On the other hand, according to the linear light source device 11 of the present embodiment, the light having the traveling component in the substrate longitudinal direction on the upper surface of the printed circuit board 12 is transmitted from the first recess 20 formed at the intermediate position between the light emitting elements 13. It can be pulled out efficiently. This effect will be described with reference to FIG.

  8A to 8C are front views schematically showing the progress of light in the vicinity of the first recess 20 of the sealing member 14. As shown to (a) of the figure, the light inject | emitted from the light emitting element 13 (not shown) advances in the inside of the sealing member 14, repeating reflection with the incident angle and reflection angle (alpha) (i). The first concave portion 20 of the linear light source device 11 causes all of the light to pass through the interface between the sealing member 14 and the outside (air), that is, the upper surface of the sealing member 14 depending on the size of α (i). It has an angle to reflect.

  The total reflection amount of light is determined by the inclination angle θ (i) of the inclined surface of the first recess 20 with respect to the upper surface direction of the printed circuit board 12 and α (i). That is, in the first recess 20, the light having an incident angle (θ (i) + α (i) −90 °) of light incident on the interface between the sealing member 14 and the outside (air) is not less than the critical angle θc. Reflected (trajectory 122).

  Further, as shown in FIG. 8C, the angle at which the light having a traveling component nearly parallel to the upper surface of the printed circuit board 12 including light having α (i) of 0 ° is reflected is set to the first recess 20. If the inclination angle θ ′ (i) is not included, the light once exits from one inclined surface of the first recess 20 but reenters the other inclined surface. The light which repeated it is radiate | emitted from the edge part of the linear light source device 11, and does not contribute to the improvement of visibility.

  In contrast, in the linear light source device 11 of the present embodiment, the inclination angle θ (i) is set to an angle that totally reflects light when α (i) is particularly 0 ° (parallel to the upper surface of the substrate). Yes. Therefore, the traveling direction of the light traveling in a direction nearly parallel to the upper surface of the printed circuit board 12 is changed by the first recess 20. A part of the light changes in the traveling direction including a large amount of components in the vertical direction on the upper surface of the substrate and is emitted from the apparatus, which contributes to improvement in visibility.

  Further, light whose incident angle (θ (i) + α (i) −90 °) is less than the critical angle θc is refracted and emitted to the outside at a refraction angle β (i) (trajectory 123). ). If the refractive index of the sealing member 14 is about 1.5, the refractive angle is larger than the incident angle because the refractive index is larger than that of external air (refractive index of about 1.0). Therefore, as shown in FIG. 8B, in the conventional light source device in which the first recess 20 is not provided, the light guided in the sealing member 14 is emitted from the end of the light source device. Therefore, visibility is not improved.

  On the other hand, in the linear light source device 11 of the present embodiment, light having an incident angle (θ (i) + α (i) −90 °) less than the critical angle θc is refracted and emitted to the outside. For this reason, the said light contributes to the improvement of visibility.

(Effects of the second recess 21)
Further, in the linear light source device 11 of the present embodiment, the light emitted from the light emitting element 13 or the light emitted from the phosphor in the fluorescent part 24 that receives light from the light emitting element 13 is directly above the light emitting element 13. It is possible to prevent the second recess 21 from going out from the outside. This effect will be described with reference to FIG.

  FIGS. 9A and 9B are front views schematically showing the progress of light in the vicinity of the second recess 21 of the sealing member 14. (A) of the figure shows a locus 124 of light emitted from the light emitting element 13 in the normal direction of the printed circuit board 12 and the inside of the sealing member 14 after the light is totally reflected at the sealing member 14-air interface. A locus 125 of light traveling in the longitudinal direction of the printed circuit board 12 is shown. Further, (b) in the figure shows a locus 126 of light emitted from the light emitting element 13 in the normal direction and a locus of light emitted to the air side after the light is refracted at the sealing member 14-air interface. 127.

  Specifically, FIG. 9A shows a case where the above method is applied from the light emitting element 13 when the inclination angle θ of the surface of the second recess 21 is larger than the total reflection angle θc (θ> θc). Traces 124 and 125 of light emitted in the linear direction and refracted or reflected at the sealing member 14-air interface are shown. On the other hand, (b) in the figure shows that the angle θ formed by the second recess 21 with respect to the upper surface of the substrate is smaller than the total reflection angle θc (θ <θc) from the light emitting element 13 in the normal direction. The traces 126 and 127 of the emitted light and refracted or reflected at the sealing member 14-air interface are shown.

  As shown in FIG. 9 (a), in the linear light source device 11, the inclination angle θ of the second recess 21 is inclined more than the critical angle θc of total reflection. Therefore, in the second recess 21, the light traveling in the normal direction on the upper surface of the printed circuit board 12 is totally reflected, so that the uniformity of the light intensity distribution in the longitudinal direction of the printed circuit board 12, that is, whether or not the light emitting element 13 is in the vicinity. The uniformity of the irrelevant luminous intensity distribution can be further improved.

  Specifically, the inclination angle θ of the second recess 21 is set larger than the critical angle θc of total reflection at the interface between the sealing member 14 and the outside. By so doing, the traveling direction of the light traveling in the upward direction from the light emitting element 13, in other words, the traveling direction of the high-intensity light emitted in the normal direction of the upper surface of the printed circuit board 12 is applied to the upper surface of the printed circuit board 12. It can be changed in a direction having parallel components. As a result, the light is guided in the sealing member 14 to reach the first recess 20, and is refracted at the interface between the first recess 20 and the outside and emitted to the outside.

Here, considering the total reflection occurring at the interface between the outside (air) and the sealing member 14, the critical angle θc of the total reflection can be obtained from the following equation (1).
n × sin (θc) = 1 (1)
In Formula (1), n is the refractive index of the resin of the sealing member 14, and generally has light wavelength dependency. For example, in the case of a typical high-refractive-index resin for coating, the refractive index n of the resin has a value of about 1.5 for light with a wavelength of 455 nm from a typical blue light-emitting element. Here, when n is 1.5 and the critical angle θc of total reflection is calculated from the equation (1), it is approximately 42 °.

  The light traveling in the normal direction from the light emitting element 13 has higher intensity than the light traveling in the other direction. For this reason, in the plane of the linear light source device 11, the light emission intensity is higher in the portion directly above the light emitting element 13 than in other positions, and uneven brightness tends to occur in the device surface.

  On the other hand, as shown in FIG. 9B, when θ <θc, the light emitted from the light emitting element 13 in the normal direction is refracted by the slope of the second recess 21, The light is emitted in a direction deviating from the axial direction. Therefore, since the intensity of the light that travels in the normal direction from the light emitting element 13 and is emitted is reduced, uneven brightness in the apparatus surface is suppressed.

  Further, as shown in FIG. 9A, when θ> θc, the light emitted from the light emitting element 13 in the normal direction is totally reflected by the slope of the second recess 21 and the normal line. In addition to deviating from the direction, the printed circuit board 12 has a traveling component in the longitudinal direction and is guided inside the sealing member 14. Finally, the light guided in the sealing member 14 with the component in the longitudinal direction of the upper surface of the printed circuit board 12 reaches the first recess 20, and the first recess 20 Refracted and emitted to the outside. Accordingly, since the light emitting element 13 does not exist, the intensity of light emitted tends to be lower than other positions, and the light emitted from the intermediate position between the light emitting elements 13 is supplemented. The brightness unevenness in is suppressed.

  In the light source device, there are a position where the luminous intensity tends to be high, such as the vicinity of the light emitting element, and a position where the luminous intensity is likely to be low, such as an intermediate position between the light emitting elements, in the plane where the light emitting element is arranged. .

(Effects of multiple groups connected in series)
Further, the linear light source device 11 of the present embodiment can suppress luminance unevenness as compared with the surface light source unit 1000 described in Patent Document 1. This effect will be described with reference to FIG. 10 and FIG. FIG. 10 is a graph showing a luminous intensity profile in the linear light source device 11 of the present embodiment. FIG. 17 is a graph showing a luminous intensity profile in the conventional surface light source unit 1000.

  In the conventional surface light source unit 1000, the LEDs are divided into two groups, the LEDs are connected in series for each group, and the LEDs belonging to the two groups are arranged alternately. In the conventional surface light source unit 1000, the luminous intensity profile in the longitudinal direction of the apparatus (LED arrangement direction) is as shown in FIG. As shown in the figure, the portion where the LED is arranged has a bright spot, and the light intensity is lowered almost uniformly (darkened) at the position where the LED is not arranged.

  Further, in the conventional surface light source unit 1000, when any of the LEDs is broken and disconnected, and the LED of the group to which this LED belongs is turned off, the luminous intensity profile in the longitudinal direction of the apparatus is shown in FIG. ) As shown. As shown in the drawing, between the LEDs of the groups that are lit, which sandwich the LEDs of the groups that are turned off, the luminous intensity is almost uniformly low, and the luminance unevenness appears remarkably.

  On the other hand, the linear light source device 11 of the present embodiment has the first and second recesses 20 and 21, so that the luminous intensity profile in the longitudinal direction of the device (the arrangement direction of the light emitting elements 13) is as shown in FIG. As shown in (a). As shown in the figure, the light intensity distribution becomes slightly higher at the position of the first recess 20.

  Further, in the linear light source device 11 of the present invention, when any one of the light emitting elements 13a is broken and disconnected, and the light emitting elements 13a of the group to which the light emitting element 13a belongs are turned off, the luminous intensity in the longitudinal direction of the apparatus. The profile is as shown in FIG. As shown in the figure, a certain amount of light intensity can be obtained even at the position of the first recess 20 adjacent to the light-emitting element 13a that is turned off, so that luminance unevenness is suppressed and the quality near the incident light is kept in a good state. It can be understood that this is possible.

  In the experiment, when one group of the light emitting elements is turned off, the luminous intensity distribution in the longitudinal direction of the substrate is reduced by 50% in the conventional light emitting device, whereas in the linear light source device 11 of the present embodiment, , Was suppressed to a decrease of 30-40%.

[Embodiment 2]
Next, another embodiment of the present invention will be described with reference to FIG. FIG. 11A is a front view schematically showing the structure of the linear light source device according to the present embodiment, and FIG. 11B is an enlarged view showing a part of the structure. . Further, (c) and (d) in the same figure are enlarged views showing a part of the modified example of the above structure.

  As shown in FIG. 11, the linear light source device 211 of the present embodiment has four layers instead of the printed circuit board 12 which is a single-sided double-sided substrate, as compared with the linear light source device 11 shown in FIGS. 1 to 10. The difference is that the printed circuit board 212 having a multilayer substrate structure having the above wiring pattern is used, the external connection terminal and the wiring pattern, and the other configurations are the same. In addition, the same code | symbol is attached | subjected to the structure which has the function similar to the structure demonstrated in the said embodiment, and the description is abbreviate | omitted.

  As shown in FIG. 11A, the printed circuit board 212 is obtained by stacking an upper layer base material, a core base material, and a lower layer base material, and has a total of four layers and seven types of wiring patterns. ing. Below, let the surface in which light emitting element 13a * 13b is provided be a 1st layer, and it will be set as a 2nd layer, a 3rd layer, and a 4th layer as it moves to a lower layer.

  As shown in FIGS. 11A and 11B, in the first group, the plurality of light emitting elements 13a are arranged between a wiring pattern 31a between an anode-side external connection terminal 251a and a cathode-side external connection terminal 252a. 32a, the through hole 41a, the wiring pattern 233a provided in the third layer of the printed circuit board 12, and the through hole 242a for electrically connecting the second and third layer wiring patterns 32a and 233a, The third-layer wiring pattern 233a and the fourth-layer cathode-side external connection terminal 252a are connected in series via a through hole 243a for electrical connection.

  On the other hand, in the second group, the plurality of light emitting elements 13b include wiring patterns 31b and 32b, through-holes 41b, and printed circuit board 12 between the anode-side external connection terminal 251b and the cathode-side external connection terminal 252b. The wiring patterns 234b provided in the fourth layer and the through holes 242b for electrically connecting the wiring patterns 31b and 234b of the first layer and the fourth layer are connected in series.

  In this embodiment, as shown in FIGS. 11A and 11B, the external connection terminals 251 a and b and 252 a and b are connected to one side of the printed board 212 by using a multilayer board as the printed board 212. Gathered at the end of the. Thereby, the LED mounting substrate that is conductively connected to a circuit (not shown) such as a mobile phone, a digital camera, or a portable game device can be reduced. As a result, it is possible to provide an LED mounting substrate that is cheaper than a structure in which external connection terminals are provided at both ends of the substrate.

  The external connection terminals 251a · b and 252a · b are collected on the lower surface of one end portion of the printed circuit board 212 as shown in FIG. 11C by changing the connection form between the wiring pattern and the through hole. Or, as shown in (d) of the figure, it can also be collected on the upper surface of one end of the printed circuit board 212.

[Embodiment 3]
Next, still another embodiment of the present invention will be described with reference to FIG. FIG. 12A is a front view schematically showing the structure of the linear light source device according to this embodiment, and FIG. 12B is an enlarged view showing a part of the structure. . Further, (c) and (d) in the same figure are enlarged views showing a part of the modified example of the above structure.

  As shown in FIG. 12, the linear light source device 311 of the present embodiment has three layers instead of the printed circuit board 12 that is a single-sided double-sided substrate, as compared with the linear light source device 11 shown in FIGS. 1 to 10. The difference is that the printed circuit board 312 having a multilayer substrate structure having the above wiring pattern is used, the external connection terminal and the wiring pattern, and the other configurations are the same. In addition, the same code | symbol is attached | subjected to the structure which has the function similar to the structure demonstrated in the said embodiment, and the description is abbreviate | omitted.

  As shown to (a) of FIG. 12, the printed circuit board 312 has the wiring pattern of the 3 layer structure on which the upper layer base material, the core base material, and the lower layer base material were piled up.

  As shown in FIGS. 12A and 12B, in the first group, the plurality of light emitting elements 13a are arranged between the anode-side external connection terminal 351a and the cathode-side external connection terminal 352a. 32a, the through hole 41a, the wiring pattern 333a provided in the third layer of the printed circuit board 12, and the through hole 342a for electrically connecting the second and third layer wiring patterns 32a and 333a. Are connected in series.

  On the other hand, in the second group, the plurality of light emitting elements 13b are arranged between the anode-side external connection terminal 351b and the cathode-side external connection terminal 352b, the wiring patterns 31b and 32b, the through holes 41b, and the printed circuit board 12. The wiring patterns 333b provided in the third layer and the through holes 342b that electrically connect the wiring patterns 31b and 333b of the first layer and the third layer are connected in series.

  According to the present embodiment, as shown in FIGS. 12A and 12B, the external connection terminals 351 a and b and 352 a and b are connected to both surfaces of the printed board 312 by using a multilayer board as the printed board 312. Can be collected at one end. Thereby, as above-mentioned, the board | substrate for LED mounting can be made small, and an inexpensive LED mounting board | substrate can be provided.

  By changing the connection form between the wiring pattern and the through hole, the external connection terminals 351a · b and 352a · b are collected on the lower surface of one end portion of the printed circuit board 312 as shown in FIG. Alternatively, as shown in (d) of FIG.

[Embodiment 4]
Next, still another embodiment of the present invention will be described with reference to FIG. FIG. 13 is a front view schematically showing the structure of the linear light source device according to this embodiment. As shown in the figure, the linear light source device 411 of the present embodiment is different from the linear light source device 311 shown in FIG. 12 in the external connection terminals and the wiring pattern, and the other configurations are the same. In addition, the same code | symbol is attached | subjected to the structure which has the function similar to the structure demonstrated in the said embodiment, and the description is abbreviate | omitted.

  As shown in FIG. 13, in the first group, the plurality of light emitting elements 13a include wiring patterns 31a and 32a, a through hole 41a, and an external connection terminal 451a on the anode side and an external connection terminal 452a on the cathode side. The wiring pattern 433a provided in the third layer of the printed circuit board 12, the through hole 442a for electrically connecting the wiring patterns 31a and 433a of the first layer and the third layer, the second layer and the third layer The wiring patterns 32a and 433a are connected in series via a through hole 443a for electrically connecting the wiring patterns 32a and 433a.

  On the other hand, in the second group, the plurality of light emitting elements 13b are provided between the anode-side external connection terminal 451b and the cathode-side external connection terminal 452b. The wiring patterns 433b provided in the third layer and the through-holes 442b for electrically connecting the wiring patterns 31b and 433b of the first layer and the third layer are connected in series.

  According to the present embodiment, as shown in FIG. 13, by using a multilayer substrate as the printed circuit board 412, the external connection terminals 451 a and b and 452 a and b are gathered at the center of the lower surface of the printed circuit board 412. In this case, the mounting substrate to be electrically connected to the circuit (not shown) of the external device can be made smaller than the configuration in which the external connection terminal is provided at one end portion of the substrate, and the cost can be reduced.

  In the present embodiment, a configuration in which a three-layer multilayer board is used as the printed board 412 is shown, but it goes without saying that this may be changed to a four-layer printed board 212 as shown in FIG. Absent.

[Embodiment 5]
Next, another embodiment of the present invention will be described with reference to FIG. FIG. 14A is a plan view showing a wiring pattern of the linear light source device according to this embodiment, and FIG. 14B is a front view schematically showing the structure of the linear light source device. is there.

  As shown in FIGS. 14A and 14B, the linear light source device 511 of the present embodiment has three light emitting elements 13 as compared to the linear light source device 11 shown in FIGS. The other structure is the same except that it is divided into groups. In addition, the same code | symbol is attached | subjected to the structure which has the function similar to the structure demonstrated in the said embodiment, and the description is abbreviate | omitted. In the following description, a member belonging to the first group is denoted by the suffix a, a member belonging to the second group is denoted by the suffix b, and a member belonging to the third group is denoted by the suffix c. Yes.

  As shown in FIGS. 14A and 14B, in the first group, the plurality of light emitting elements 13a are arranged between the printed circuit board 12 between the anode-side external connection terminal 551a and the cathode-side external connection terminal 552a. Are connected in series via a wiring pattern 531a provided on the front surface, a wiring pattern 532a provided on the back surface of the printed circuit board 12, and a through hole 541a for electrically connecting the wiring patterns 531a and 532a on the front surface and the back surface. Has been.

  On the other hand, in the second group, the plurality of light emitting elements 13b include a wiring pattern 531b provided on the surface of the printed circuit board 12 between the anode side external connection terminal 551b and the cathode side external connection terminal 552b, and the printed circuit board 12. Are connected in series via a wiring pattern 532b provided on the back surface of the wiring pattern and through-holes 541b for electrically connecting the wiring patterns 531b and 532b on the front surface and the back surface.

  In the third group, the plurality of light emitting elements 13c include a wiring pattern 531c provided on the surface of the printed circuit board 12 between the anode side external connection terminal 551c and the cathode side external connection terminal 552c, and the printed circuit board 12. Are connected in series via a wiring pattern 532c provided on the back surface of the wiring pattern and through-holes 541c for electrically connecting the wiring patterns 531c and 532c on the front surface and the back surface.

  Further, as shown in FIG. 14, a single-layer double-sided board is used as the printed board 12, and a plurality of wiring patterns 532a to 532c in the first group, the second group, and the third group are formed on the back surface thereof. Is formed. Further, in the linear light source device 511 of the present embodiment, external connection terminals 551a to c and 552a to c for supplying current to the light emitting elements 13a to 13c are provided at both ends of the printed circuit board 12.

  Thus, the present invention can also be applied to a configuration in which a plurality of light emitting elements 13 are divided into three or more groups and the light emitting elements 13 are connected in series for each group. In the present embodiment, a single-layer double-sided board is used as the printed board 12, but the present invention is not limited to this, and a multilayer board may be used. Further, the external connection terminals 551a to c and 552a to c may not be arranged at both ends of the printed circuit board 12, and may be arranged, for example, at the center of the printed circuit board 12.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  In the surface light emitting device including the linear light source device of each embodiment and a light guide plate for emitting light incident linearly from the linear light source device as planar light, the luminance unevenness is small, The bright line can be small in the vicinity of the light incident surface. In addition, a liquid crystal display device that performs display output by including a liquid crystal panel that modulates light from the surface light-emitting device can have a display quality with less luminance unevenness. In addition, although the linear light source device of each embodiment has a two-system lighting circuit configuration, even if a short circuit or an opening occurs at one location, the entire surface light emitting device or liquid crystal display device does not become unlit. Further, in the two-system lighting circuit configuration, when the liquid crystal display device is considered, it is possible to drive the display image in two frames and to perform power saving driving.

  As described above, the drive voltage can be lowered, the number of light emitting elements can be increased, and the increase in the scale of the device can be suppressed, so that it can be applied to a light source of an arbitrary display device having a backlight. It is suitable for a light source of a display device such as a mobile phone, in particular, a mobile phone having a narrowed frame, a mobile information terminal, a digital camera, or a portable game machine.

11 Linear Light Source Device 12 Printed Circuit Board (Board)
13 (ac) Light-emitting element 14 Sealing member 15/16 Reflective sheet 20 First recess 21 Second recess 22 Planar portion 23 End 24 Fluorescent portion 31a / b Surface wiring pattern 32a / b Rear surface wiring pattern 41a / b Through hole 51a / b External connection terminal 52a / b on the anode side External connection terminal 60 on the cathode side Mounting substrate 61 Solder 100 Printed circuit board 101 Sealing member 110 Plate member 120 Dicing blade 211 Linear light source device 212 Printed circuit board (Board, additional board)
233a Wiring pattern 234b Wiring pattern 242a / b Through hole 243a Through hole 251a / b External connection terminal 252a / b External connection terminal 311 Linear light source device 312 Printed circuit board (board, additional board)
333a / b Wiring pattern 342a / b Through hole 351a / b External connection terminal 352a / b External connection terminal 411 Linear light source device 412 Printed circuit board (board, additional board)
433a / b Wiring patterns 442a / b Through holes 443a Through holes 451a / b External connection terminals 452a / b External connection terminals 511 Linear light source devices 531a-c Wiring patterns 532a-c Wiring patterns 541a-c Through holes 551a-c External connections Terminals 552a-c External connection terminal 1001 Light guide plate

Claims (11)

A linear light source device that irradiates linear light from a plurality of light emitting elements arranged in a longitudinal direction on a long substrate,
A wiring pattern formed on the substrate and for connecting the plurality of light emitting elements in series;
The light emitting element and the wiring pattern are divided into a plurality of groups,
In each group, the light-emitting elements are connected in series via the wiring pattern, and power is supplied to each group.
The wiring patterns of each group are formed on the back surface of the substrate ,
The light emitting elements of the above groups are arranged alternately,
Further comprising through holes for electrically connecting the wiring patterns on the front and back surfaces of the substrate,
The through hole is provided between the light emitting elements,
The through hole for connecting a wiring pattern of one group and the through hole for connecting a wiring pattern of another group are provided at different positions in the short direction of the substrate . A linear light source device. A light-transmitting sealing member that seals the plurality of light-emitting elements;
The sealing member is
A first recess that is provided between the light emitting elements adjacent to each other and bends light guided in the sealing member to guide part or all of the light to the outside;
A second recess that bends light emitted from the light emitting element in the normal direction of the upper surface of the substrate and guides a part or all of the light into the sealing member. The linear light source device according to claim 1 . The linear light source device according to claim 2 , wherein the first concave portion of the sealing member totally reflects the light guided in the longitudinal direction in the sealing member. The second recess of the sealing member, the linear light source device according to claim 2 or 3, characterized in that totally reflects the light irradiated from the light emitting element in the normal direction of the substrate top surface. The first recess and the second recess of the sealing member have a V-shaped cross section along the longitudinal direction of the substrate, according to any one of claims 2 to 4. The linear light source device described. The sealing member includes a phosphor, and a linear light source device according to any one of claims 2, characterized in that it comprises a fluorescent portion for covering the respective light emitting element to 5 . One or more additional substrates are stacked on the lower surface of the substrate,
External connection terminals for supplying power to the light emitting elements of each group are provided on the substrate and the additional substrate,
The external connection terminal may utilize additional wiring pattern formed on the additional substrate, claim 1, characterized in that provided on one end of the substrate and the additional substrate until 6 1 The linear light source device according to item.   Each group has two external connection terminals,
  The linear light source device according to claim 7, wherein the light emitting elements included in the same group are arranged between the two external connection terminals.   9. The linear light source device according to claim 1, wherein a wiring pattern of each group is further formed on an upper surface of the substrate. The linear light source device according to any one of claims 1 to 9,
A surface light emitting device comprising: a light guide plate for emitting light linearly incident from the linear light source device as planar light.   A liquid crystal display device that performs display output by comprising the surface light emitting device according to claim 10 and a liquid crystal panel that modulates light from the surface light emitting device.

Images