JP2008108994A - Luminescent device and planar light source using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a luminescent device that has an appropriate light distribution characteristic relative to a light-guide plate, and a planar light source using the same. <P>SOLUTION: The luminescent device comprises a luminescent element and a case for storing the luminescent element, wherein the case has a first groove-shaped recess which is provided along the longitudinal direction of the case, and a second recess which is provided in substantially the center of the bottom surface of the first recess. The luminescent element is disposed in the bottom surface of the second recess. The second recess is sealed with a translucent material. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light emitting device and a planar light source using the same, and more particularly to a light emitting device and a planar light source for backlighting a liquid crystal display.

  In recent years, backlight units (planar light sources) for liquid crystal displays that are required to be thinner are replaced with cold cathode fluorescent lamp units and LED lamps (light emitting devices) that emit white light and the emitted light in a desired direction. Units that combine a light guide that obtains a planar light source by conversion have become mainstream.

For example, as shown in FIG. 3, an LED lamp 10 used in such a unit includes a case 1 having a recess 1a on one surface and a blue light emitting LED chip 2 mounted in the recess 1a. 1a is sealed with a resin containing a yellow phosphor that uses blue light as excitation light (see, for example, Patent Document 1).
JP 2004-193537 A

  By the way, the LED lamp 10 is required to have a light distribution characteristic that is narrow enough to allow the emitted light to enter the light guide plate in the thickness direction of the light guide plate, as indicated by the alternate long and short dash line in FIG. The Further, with respect to the lateral direction of the light guide plate, as shown by a one-dot chain line in FIG. 4B, a sufficiently wide light distribution characteristic is required to spread the emitted light to every corner of the light guide plate.

  However, in the LED lamp 10, since the light emitted from the LED chip 2 is dispersed by refraction at the interface between the resin and air, the thickness direction of the light guide plate is indicated by a broken line in FIG. As such, the light distribution characteristics are too wide. Further, with respect to the lateral direction of the light guide plate, the light emitted from the LED chip 2 is caused by the effect of condensing by reflection on the inner surface of the recess 1a, as shown by the broken line in FIG. The light distribution characteristics are too narrow. For these reasons, it is difficult to say that the light distribution characteristics required for the light guide plate are provided.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a light emitting device having an appropriate light distribution characteristic with respect to a light guide plate and a planar light source using the light emitting device. .

  In the light-emitting device including the light-emitting element and a case for housing the light-emitting element, the case includes a groove-shaped first recess provided in a longitudinal direction in the longitudinal direction of the case, and the first A second concave portion provided at the center of the bottom surface of the first concave portion, and the light emitting element is disposed on the bottom surface of the second concave portion, and only the second concave portion is sealed with a translucent material. It is solved by a light emitting device characterized in that

  In addition, the above-described problem is solved by a planar light source including the light-emitting device described above and a light guide plate that changes the direction of light emitted from the light-emitting device and emits light from only one predetermined surface. The

  According to the light emitting device of the present invention, when the emitted light from the light emitting element is emitted from the second recess, the light dispersed at the interface between the air and the translucent material is reduced in the thickness of the case in the first recess. For the light in the direction, the light distribution characteristics are narrowed by reflecting the light in the direction where the light is collected on the inner side surface, but for the light in the longitudinal direction of the case, there is no inner side surface in that direction, so the light distribution characteristics are Widen without narrowing. Thereby, the light-emitting device which has a suitable light distribution characteristic with respect to a light-guide plate can be obtained.

  Further, by combining the light emitting device and the light guide plate as described above, a planar light source that does not cause uneven color of light can be obtained.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

1A, 1B, and 1C are diagrams showing a light-emitting device according to an embodiment of the present invention. FIG. 1A is a perspective view, and FIG. A cross-sectional view taken along the line AA ′, FIG. 5C is a cross-sectional view taken along the line BB ′ of FIG.
The LED lamp 30 according to the present embodiment includes a groove-shaped first recess 21a provided in a longitudinal direction in the longitudinal direction of the case, and a second recess 21b provided in the center of the first recess. A case 30 and an LED chip mounted on the bottom surface of the second recess 21b are provided, and only the second recess is sealed with a translucent resin.
The case 20 is formed of a resin such as polyamide or liquid crystal polymer mixed with a white dye.

  The inner surface of the first recess 21a is provided with an inclination in the range of 50 ° to 70 ° with respect to the bottom surface of the first recess 21a. The inner surface of the second recess 21b parallel to the longitudinal direction of the case 30 is formed perpendicular to the bottom surface of the second recess 21b. Therefore, the light whose light collecting property is enhanced by the inner surface of the second recess 21b is incident on the interface between the resin sealing portion and the air, and further, the light dispersed at this interface is within the first recess 21a. The light distribution characteristic can be narrowed by the side surface.

  On the other hand, the first recess has no inner surface in the longitudinal direction of the case. For this reason, the light in the longitudinal direction of the case is not suppressed from being dispersed at the interface between the resin sealing portion and the air, so that the light distribution characteristic is widened. Note that the inner side surface of the second recess 21a parallel to the thickness direction of the case 30 is 50 ° to 70 ° with respect to the bottom surface of the first recess 21a in order to ensure a certain degree of light condensing performance in the longitudinal direction of the case. An inclination in the range of ° is provided.

  From the viewpoint of light reflectivity, it is desirable to deposit Ag or Al on the inner side surfaces of these recesses 21a and 21b.

The LED chip 11 has a gallium nitride compound semiconductor (Al _x Ga _y In _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) on a single crystal substrate such as sapphire, silicon carbide, or gallium nitride. , 0 ≦ x + y ≦ 1)) A plurality of layers are stacked, and emits blue light.
The sealing part 15 is formed from an epoxy resin, a silicon resin, a fluororesin, or the like. This is made to contain a yellow conversion phosphor, and white light is obtained by the mixed light of the blue emission light from the LED chip and the yellow wavelength conversion light from the phosphor.

  According to the LED lamp of the present embodiment having the above configuration, it is possible to widen the light distribution characteristic in the longitudinal direction of the case while narrowing the light distribution characteristic in the thickness direction of the case. Thereby, the LED lamp which has a suitable light distribution characteristic with respect to a light-guide plate can be obtained.

  FIG. 2 is a perspective view showing the backlight unit according to the embodiment of the present invention.

  The backlight unit of the present embodiment is disposed on the LED lamps 30a, 30b, and 30c and the light extraction surface side of the LED lamps, converts the direction of light emitted from the LED lamps 30a, 30b, and 30c, and has a predetermined surface. And a light guide plate 40 that emits light L only from the light source.

  According to such a backlight unit, since the LED lamps 30a, 30b, and 30c have appropriate light distribution characteristics with respect to the light guide plate, even if the LED lamps are arranged at a wide interval, light color unevenness does not occur. .

In the above embodiment, the case is formed of white resin, but it may be formed of ceramics. In the above embodiment, the combination of the blue light emitting LED chip and the yellow conversion phosphor is described. However, the present invention is not limited to this, and the combination of the blue light emitting LED, the green light emitting phosphor, and the red light emitting phosphor is used. It can also be applied to other combinations of LED lamps, such as a combination of an ultraviolet light emitting LED and a blue light emitting phosphor, a green light emitting phosphor and a red light emitting phosphor.
(Example)
A case having dimensions of a polyphthalamide containing a white dye as a raw material, a longitudinal direction of 4.2 mm, a thickness direction of 2.2 mm, and a depth direction of 1 mm was prepared. Here, the first recess has a depth of 0.3 mm, and the inner side surface is provided with an inclination of 50 ° with respect to the bottom surface. On the other hand, the depth of the second recess was 0.5 mm, and the inner side surface in the longitudinal direction of the case was provided with an inclination of 58 ° with respect to the bottom surface.

  Next, an LED chip is mounted in the center of the second recess, and an epoxy resin containing a YAG: Ce phosphor is filled and cured so as to cover only the second recess, thereby creating a sealing portion. . Through the above steps, an LED lamp as shown in FIG. 1 was produced.

  When the light distribution characteristics of this LED lamp were measured, the light distribution characteristics were narrowed for the light in the thickness direction of the case and the light in the longitudinal direction of the case was compared with the conventional LED lamp as shown in FIG. It was confirmed that the light distribution characteristics were wide and the light distribution characteristics were appropriate for the light guide plate.

1A, 1B, and 1C are diagrams showing an LED lamp according to an embodiment of the present invention. FIG. 1A is a perspective view, and FIG. A cross-sectional view taken along the line AA ′, FIG. 5C is a cross-sectional view taken along the line BB ′ of FIG. FIG. 2 is a perspective view showing the backlight unit according to the embodiment of the present invention. FIG. 3 is a cross-sectional view showing a conventional LED lamp. 4 (a) and 4 (b) are diagrams showing a conventional backlight unit, in which FIG. 1 (a) is a partial side view and FIG. 4 (b) is a partial top view.

Explanation of symbols

21 Case 21a 1st recessed part 21b 2nd recessed part 32 LED chip 30, 30a, 30b, 30c Light-emitting device 40 Light-guide plate L Light

Claims (7)

In a light emitting device including a light emitting element and a case for housing the light emitting element,
The case has a groove-shaped first recess provided by cutting in the longitudinal direction of the case, and a second recess provided in a substantially central portion of the bottom surface of the first recess,
The light emitting device is disposed on a bottom surface of the second recess, and only the second recess is sealed with a light-transmitting material.   The light-emitting device according to claim 1, wherein the light-transmitting material contains a phosphor.   3. The light emitting device according to claim 2, wherein white light is obtained by a mixed light of light emitted from the light emitting element and wavelength converted light from the phosphor.   The inner surface of the first recess has an inclination of an angle of 50 ° to 70 ° with respect to the bottom surface of the first recess. 2. The light emitting device according to item 1.   5. The inner surface of the second concave portion parallel to the longitudinal direction of the case is provided perpendicular to the bottom surface of the second concave portion. The light emitting device according to item.   The inner side surface of the second concave portion parallel to the thickness direction of the case has an inclination of an angle of 50 ° to 70 ° with respect to the bottom surface of the second concave portion. The light-emitting device according to claim 5. A light emitting device according to any one of claims 1 to 6,
A planar light source comprising: a light guide plate that changes a direction of light emitted from a light emitting device and emits light from only one predetermined surface.

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