JP2011171143A - Linear light emitting device - Google Patents

Abstract

The light distribution of an LED package is narrow with a directivity at the center. Therefore, when a side-edge type planar light emitting device is configured in combination with the light guide plate, a large amount of light enters the light guide plate perpendicularly and escapes, and the brightness of the light guide plate is reduced.
An LED package includes a mounting substrate having an inverted T-shaped cross section having a reflecting wall, a row of LED chips mounted on the mounting substrate, and a phosphor-containing silicone resin layer. One row of LED chips 42 is arranged so as to be offset from the center of the mounting substrate 41 and to face the reflecting wall 41a. As indicated by the thick arrows X 1 and X 2, most of the light from the LED chip 42 of the LED package 4 is incident from the side surface of the light guide plate 2 and reflected between the front and back surfaces of the light guide plate 2. The scattered light is scattered by the dot pattern 2c on the back surface, and the scattered light exits from the light exit surface on the front surface of the light guide plate 2 and enters the LCD panel 1 through the diffusion plate 2b.
[Selection] Figure 1

Description

  The present invention relates to a linear light emitting device comprising a light emitting element package, such as a light emitting diode (LED) package. For example, a linear light emitting device is combined with a light guide plate to form a side edge type planar light emitting device, and is used as a backlight light source of a liquid crystal display (LCD) device.

  2. Description of the Related Art A planar light emitting device used as a backlight light source of an LCD device is mainly a device using an LED element instead of a cold cathode fluorescent lamp (CCFL). Thereby, thickness reduction, weight reduction, power saving, etc. are aimed at. Surface light-emitting devices using LED elements are roughly classified into side-edge type and direct type, but side-edge type surface light-emitting devices are particularly superior in terms of thinning compared to direct-type surface light-emitting devices. Yes.

  FIG. 15 shows a side edge type planar light emitting device including a conventional linear LED package (see Patent Document 1).

  In the side edge type planar light emitting device of FIG. 15, for example, the light guide plate 2 is disposed on the back surface of the LCD panel 1, and the LED package 3 is disposed on the side surface of the light guide plate 2.

  A reflective sheet 2 a is provided on the back side of the light guide plate 2, and a diffusion plate 2 b is provided on the front side of the light guide plate 2. Further, a dot pattern 2 c is printed on the back surface of the light guide plate 2. Both the reflection sheet 2a and the dot pattern 2c are for irregularly reflecting (scattering) light, and the diffusion plate 2b is for diffusing light.

  The LED package 3 includes a mounting substrate 31, an LED chip 32 mounted on the mounting substrate 31, and a light distribution distribution adjusting convex lens 33 provided on the LED chip 32.

  In FIG. 15, as indicated by a thin line arrow X, light is incident from the side surface of the light guide plate 2 from the LED chip 32 of the LED package 3, and the back surface of the light guide plate 2 is reflected between the front surface and the back surface in the light guide plate 2. Are scattered by the dot pattern 2c, and the scattered light is emitted from the emission surface on the front surface of the light guide plate 2 and is incident on the LCD panel 1 through the diffusion plate 2b.

JP 2004-61693 A JP 2003-297127 A

  However, in the conventional side-edge type planar light emitting device of FIG. 15, the light distribution of the LED package 3 by the convex lens 33 is narrow at the directivity angle as shown in FIG. As a result, most of the light incident on the light guide plate 2 from the LED package 3 is incident on the light guide plate 2 vertically as shown by the thick arrow Y in FIG. The light guide plate 2 will come off. As a result, the scattered light in the dot pattern 2c of the light guide plate 2 is reduced, and the amount of light reaching the LCD panel 1 is reduced, so that the luminance of the light guide plate 2 is lowered.

  In addition, a concave lens can be provided on the LED package 3 to widen the directivity angle of the light distribution in the short side direction of the light guide plate (see Patent Document 2). In Patent Document 2, the light distribution in the long side direction of the light guide plate is expanded. However, even in this case, the light component perpendicularly incident on the light guide plate is not small, so that the luminance of the light guide plate is also lowered. Further, if the mounting position of the concave lens is shifted, the light distribution is largely shifted, and the efficiency of taking light into the light guide plate may be lowered.

  In order to solve the above-described problems, a linear light-emitting device according to the present invention includes a plurality of light-emitting elements mounted on a mounting substrate, and a reflection wall provided on the mounting substrate corresponding to each of the plurality of light-emitting elements. The plurality of light emitting elements are arranged along the longitudinal direction of the mounting substrate and shifted from the center of the mounting substrate, and the reflecting wall is provided to face one side surface of the light emitting element. Thereby, the directivity of the light distribution is directed outward and the light directed on the axis is reduced.

  The mounting substrate has an inverted T-shaped cross section. The inverted T-shaped mounting substrate can be easily formed by, for example, pressing.

  The mounting substrate has an L-shaped cross-sectional shape. A mounting substrate having an L-shaped cross section can be formed by bending a flat mounting substrate.

  Furthermore, the L-shaped cross-section reflecting wall portion of the mounting board described above can be made obliquely inside and outside, or can be made two-step obliquely inside.

  According to the present invention, since the light emitted from the light emitting element is reflected by the reflecting wall, the directivity of the light distribution is directed outward and the light directed on the axis is reduced. When applied to the side surface of the light guide plate of the light emitting device, the light component perpendicularly incident on the light guide plate decreases and the light emitted to the front surface of the light guide plate increases, so that the brightness of the light guide plate can be improved. In the present specification, “outside” refers to the reflection sheet side and the diffusion plate side (that is, the front surface or the back surface of the light guide plate).

1 is a cross-sectional view showing a side edge type planar light emitting device including a first embodiment of a linear LED package according to the present invention. 1 shows an example of a detailed arrangement of the LED package of FIG. 1, (A) is a plan view, (B) is a sectional view taken along line BB of (A), and (C) is a sectional view taken along line CC of (A). It is. It is a figure which shows the light distribution of the LED package of FIG. 1 shows another example of a detailed arrangement of the LED package of FIG. 1, (A) is a plan view, (B) is a sectional view taken along line BB of (A), and (C) is a line CC of (A). It is sectional drawing. It is sectional drawing which shows the example of a change of the LED package of FIG. It is sectional drawing which shows 2nd Embodiment of the LED package which concerns on this invention. It is sectional drawing which shows the example of a change of the LED package of FIG. It is sectional drawing which shows 3rd Embodiment of the LED package which concerns on this invention. It is sectional drawing which shows the example of a change of the LED package of FIG. It is sectional drawing which shows 4th Embodiment of the LED package which concerns on this invention. It is sectional drawing which shows the example of a change of the LED package of FIG. It is sectional drawing which shows 5th Embodiment of the LED package which concerns on this invention. It is sectional drawing which shows the example of a change of the LED package of FIG. 4 is a flowchart for explaining a method of manufacturing an LED package according to the present invention. It is sectional drawing which shows the side edge type planar light-emitting device containing the conventional linear LED package. It is a figure which shows the light distribution of the LED package of FIG.

  FIG. 1 is a sectional view showing a side-edge type planar light emitting device including the first embodiment of a linear LED package according to the present invention, FIG. 2 shows an example of a detailed arrangement of the LED package of FIG. 1A is a plan view of a reflecting wall and an LED chip in FIG. 1, FIG. 2B is a sectional view taken along line BB in FIG. 1A, and FIG. 2C is a sectional view taken along line CC in FIG.

  In FIG. 1, a linear LED package 4 is provided instead of the linear LED package 3 of FIG. That is, the LED package 4 includes an inverted T-shaped mounting substrate 41 having a reflecting wall 41a, a row of LED chips 42 mounted on one side of the reflecting wall 41a of the mounting substrate 41, and a phosphor-containing silicone resin layer 43. It becomes more. The mounting substrate on the other side (opposite side of the LED chip 42) of the reflection wall 41a of the mounting substrate 41 is also sealed with silicone resin, which increases the bonding area with the mounting substrate and increases the adhesive strength. Is increasing.

  The mounting substrate 41 is made of a highly reflective and corrosion-resistant metal such as Al or Cu. The mounting substrate 41 may be Al (increased reflection Al) whose surface has been subjected to enhanced reflection alumite treatment in order to increase brightness. Moreover, what gave Ag plating to Cu may be used. Further, the inverted T-shape in FIG. 1 of the reflection wall 41a of the mounting substrate 41 can be formed by, for example, pressing.

  The LED chip 42 is a laterally conductive element with a back surface insulation formed on a sapphire substrate. A longitudinal conduction element may be used. In the case of a laterally conductive element that is insulated from the back, it is connected in series, while in the case of a vertically conductive element, it is connected in parallel.

  As shown in FIGS. 1 and 2, one row of LED chips 42, for example, five LED chips 42 is displaced from the center of the mounting substrate 41 and one chip side surface 42a is reflected from the reflecting wall 41a toward the diffusion plate 2b. It arrange | positions so that the wall 41a may be opposed, and is connected in series by the Au bonding wire 44. FIG. In addition, on both ends of the mounting substrate 41, current-carrying substrates 45 for supplying power to the LED chip 42 are provided. Here, the LED chip 42 is arranged along the longitudinal direction of the mounting substrate 41 as shown in FIG.

  In the side edge type planar light emitting device of FIG. 1, the light distribution of the LED package 4 is directed on the axis with the directivity angle directed outward by the reflecting wall 41a of the mounting substrate 41 as shown in FIG. There is little light and much light is directed outward. Further, since the LED package 4 has the above configuration, the light from the LED package 4 is shifted from the center (Z-Z line) of the light guide plate 2 and is incident on the light guide plate 2. Few. Therefore, in FIG. 1, as indicated by the thick arrows X1 and X2, most of the light from the LED chip 42 of the LED package 4 is incident from the side surface 2d of the light guide plate 2 and between the front and back surfaces in the light guide plate 2. While being reflected, the light is scattered by the dot pattern 2 c on the back surface of the light guide plate 2, and this scattered light is emitted from the exit surface on the front surface of the light guide plate 2 and enters the LCD panel 1 through the diffusion plate 2 b. The light indicated by the thick line arrow X1 indicates light reflected by the reflection wall 41a of the mounting board 41, and the light indicated by the thick line arrow X2 indicates light that is not reflected by the reflection wall 41a of the mounting board 41. In any light, the incident angle of the light guide plate 2 is not vertical. In other words, light that enters the light guide plate 2 perpendicularly and does not reflect on the front and back surfaces of the light guide plate 2 and passes through the light guide plate 2 (light that does not face the back surface of the LCD panel 1) is reduced. In this way, the amount of light scattered in the dot pattern 2c of the light guide plate 2 increases and the amount of light reaching the LCD panel 1 increases, and thus the front luminance of the light guide plate 2 is improved.

  The LED chips 42 are arranged so as to be shifted from the center of the mounting substrate 41 and the light guide plate 2, and all the LED chips 42 do not necessarily have to be on one side of the center of the mounting substrate 41. For example, as shown in FIG. 4, the LED chips 42 may be arranged in a staggered manner, and the reflection walls 41a of the mounting substrate 41 may be arranged in a staggered manner.

  FIG. 5 is a sectional view showing a modification of the LED package 4 of FIG. 5, the silicone resin layer 43 in FIG. 1 is replaced with silicone resin convex lenses 43 ′ and 43 ″ to make the light distribution more outside. Even in this case, the light directed on the axis is small. Specifically, the silicone resin convex lens 43 ′ in FIG. 5A has a curved surface facing inward, and the silicone resin convex lens 43 ″ in FIG. 5B has an inner side (reflection wall side) and an outer side (reflection wall). The other side is curved.

  FIG. 6 is a sectional view showing a second embodiment of a linear LED package according to the present invention.

  In FIG. 6, a linear LED package 5 is provided instead of the linear LED package 4 of FIG. That is, the LED package 5 includes a mounting substrate 51 having a substantially L-shaped cross section having a reflecting wall 51 a, a row of LED chips 52 mounted on the mounting substrate 51, and a phosphor-containing silicone resin layer 53.

  The substantially L-shaped reflection wall 51a of the mounting substrate 51 can be easily formed by bending a flat mounting substrate. Therefore, the reflecting wall 51a can be easily made higher than the reflecting wall 41a of the first embodiment, and as a result, the light distribution can be made more outward. In FIG. 6, X1 indicates light reflected by the reflection wall 51a, and X2 indicates light not reflected by the reflection wall 51a.

  FIG. 7 is a cross-sectional view showing a modified example of the LED package 5 of FIG. 7, the silicone resin layer 53 in FIG. 6 is replaced with silicone resin convex lenses 53 ′ and 53 ″ to make the light distribution more outside. In this case, too, the light directed on the axis is small. Specifically, the silicone resin convex lens 53 ′ in FIG. 7A has a curved surface facing inward, and the silicone resin convex lens 53 ″ in FIG. 7B has a curved surface facing inward and outward. .

  FIG. 8 is a sectional view showing a third embodiment of a linear LED package according to the present invention.

  In FIG. 8, the LED chip 52 in FIG. 6 is brought close to the reflecting wall 51a. For example, the distance between the LED chip 52 and the reflecting wall 51a is reduced to about 0.1 mm or less. Thereby, a light distribution can be made more outside.

  FIG. 9 is a cross-sectional view showing a modified example of the LED package 5 of FIG. Also in FIG. 9, the silicone resin layer 53 of FIG. 8 is replaced with the silicone resin convex lenses 53 ', 53 "to make the light distribution more outside. In this case as well, the axial directivity is small.

  FIG. 10 is a sectional view showing a fourth embodiment of the linear LED package according to the present invention.

  In FIG. 10, a linear LED package 6 is provided instead of the linear LED package 4 of FIG. In other words, the LED package 6 includes a mounting substrate 61 having a substantially L-shaped cross section having a reflecting wall 61a, a row of LED chips 62 mounted on the reflecting wall 61a side of the mounting substrate 61, and a phosphor-containing silicone resin layer 63. Become.

  The oblique substantially L-shape of the reflection wall 61a of the mounting substrate 61 can be easily formed by bending a flat mounting substrate. Therefore, the reflecting wall 61a can be easily made higher than the reflecting wall 41a of the first embodiment, and as a result, the light distribution can be made more outward. In FIG. 10, X1 indicates light reflected by the reflecting wall 61a, and X2 indicates light that is not reflected by the reflecting wall 61a. Moreover, the substantially L-shaped bending angle (including the inner and outer directions) of the reflecting wall 61a is not limited.

  FIG. 11 is a cross-sectional view showing a modified example of the LED package 6 of FIG. 11, the silicone resin layer 63 in FIG. 10 is replaced with silicone resin convex lenses 63 ′, 63 ″ to make the light distribution more outside. In this case as well, the axial directivity is small. Specifically, the silicone resin convex lens 63 ′ of FIG. 11A has a curved surface facing inward, and the silicone resin convex lens 63 ″ of FIG. 11B has a curved surface facing inward and outward.

  FIG. 12 is a sectional view showing a fifth embodiment of a linear LED package according to the present invention.

  In FIG. 12, the tip of the reflecting wall 61a of FIG. 10 is processed inside the package. That is, the mounting substrate 61 has a substantially L-shape that is two-step diagonally inside.

  The two-stage diagonally inner L-shape of the reflection wall 61a of the mounting substrate 61 can be easily formed by bending a flat mounting substrate. As a result, the light distribution can be further outward. Also in FIG. 12, X1 indicates light reflected by the reflecting wall 61a, and X2 indicates light not reflected by the reflecting wall 61a.

  FIG. 13 is a cross-sectional view showing a modified example of the LED package 6 of FIG. In FIG. 13, the silicone resin layer 63 in FIG. 12 is replaced with silicone resin convex lenses 63 ′ and 63 ″ to make the light distribution more outside. Also in this case, the axial directivity is small. Specifically, the silicone resin convex lens 63 ′ of FIG. 13A has a curved surface facing inward, and the silicone resin convex lens 63 ″ of FIG. 13B has a curved surface facing inward and outward.

  Next, a method for manufacturing an LED package according to the present invention will be described. As an example of the LED package, the structure shown in FIG. 5B is adopted and described with reference to the flowchart of FIG. The size of the LED package is, for example, about 2.5 mm × about 150 mm × height about 2 mm. Further, the thickness of the mounting substrate 41 is, for example, 0.3 mm to 1.0 mm, and the height of the reflection wall 41a is about 1 mm. Furthermore, the height of the convex lens portion of the silicone resin convex lens 43 ″ is, for example, 0.5 mm or more.

  First, in step 1401, a flat mounting board is pressed to form a mounting board 41 having an inverted T-shaped cross section.

  Next, in step 1402, a bonding agent such as a white silicone adhesive is applied on the mounting substrate 41.

  Next, in Step 1403, the LED chip 42 and the current-carrying substrate 45 are mounted and the adhesive is cured. The energization substrate 45 is, for example, a glass epoxy substrate, a metal core substrate, or a ceramic substrate.

  Next, in step 1404, the LED chip 42 and the current-carrying substrate 45 are connected by the Au bonding wire 44.

  Finally, in step 1405, a silicone resin is formed, and a convex lens is further processed to form a silicone resin convex lens 43 ″. At this time, the mounting accuracy of the silicone resin convex lens 43 ″ is about ± 0.03 mm, and the LED chip 42 Even if mounting accuracy is taken into account, it becomes as high as ± 0.05mm.

  In the case of an LED package using a mounting substrate having an L-shaped cross section, a mounting substrate having a substantially L-shaped cross section is formed in step 1401 by bending the flat mounting substrate.

The present invention also provides the following configuration.
A planar shape comprising a light guide plate, a linear light-emitting device that allows light to enter the side surface of the light guide plate, a reflection sheet provided on the back surface of the light guide plate, and a diffusion plate provided on the front surface of the light guide plate A light emitting device,
The linear light-emitting device is
A plurality of light emitting elements mounted on a mounting substrate;
A reflective wall provided corresponding to each of the plurality of light emitting elements on the mounting substrate;
Comprising
The plurality of light emitting elements are arranged along the longitudinal direction of the mounting substrate and shifted from the center of the side surface of the mounting substrate and the light guide plate,
The planar light emitting device, wherein the reflection wall is provided to face one side surface of the light emitting element.

1: LCD panel 2: Light guide plate 2a: Reflective sheet 2b: Diffusion plate 2c: Dot pattern 2d: Light guide plate side surfaces 3, 4, 5, 6: LED packages 31, 41, 51, 61: Mounting substrates 32, 42, 52 62, 62: LED chip 42a: LED chip side surface 33: convex lenses 41a, 51a, 61a: reflecting walls 43, 53, 63: silicone resin layers 43 ′, 43 ″, 53 ′, 53 ″, 63 ′, 63 ″: Silicone resin convex lens 44: Au bonding wire 45: Current-carrying substrate

Claims (8)

A plurality of light emitting elements mounted on a mounting substrate;
A reflective wall provided corresponding to each of the plurality of light emitting elements on the mounting substrate;
Comprising
The plurality of light emitting elements are arranged along the longitudinal direction of the mounting substrate and shifted from the center of the mounting substrate,
The reflective wall is a linear light emitting device provided to face one side surface of the light emitting element.   The linear light-emitting device according to claim 1, wherein the mounting substrate has an inverted T-shaped cross section.   The linear light-emitting device according to claim 1, wherein the mounting substrate has an L-shaped cross-sectional shape.   The linear light-emitting device according to claim 3, wherein portions of the reflection wall having an L-shaped cross-sectional shape of the mounting substrate are formed obliquely inside and outside.   The linear light-emitting device according to claim 3, wherein a portion of the reflection wall having an L-shaped cross-sectional shape of the mounting substrate is inclined in two steps.   The linear light-emitting device according to claim 1, wherein a distance between the light-emitting element and the reflection wall is about 0.1 mm or less.   The linear light-emitting device according to claim 1, further comprising a resin layer formed on the light-emitting element. The linear light-emitting device according to claim 7, wherein the resin layer has a lens shape.

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