JP2010183061A - Light-emitting device and lighting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting device for controlling the light distribution of an LED by a phosphor layer for converting light, and to provide a lighting system using the light-emitting device. <P>SOLUTION: The light-emitting device 30 includes: an LED packaging substrate 31 where wiring is formed; an LED 32 for applying light to B stuck to the LED packaging substrate 31; and the phosphor layer 33 including a fluorescent substance for applying light to Y by the light of B emitted from the LED 32. A surface 33a at a side opposite to the LED 32 of the phosphor layer 33 is composed of a curved surface falling toward the LED 32. Furthermore, an incline falling conically toward the LED 32 is composed so that the curved surface is surrounded. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a light emitting device and a lighting device using the same.

  A cold cathode discharge tube (CCFL: Cold Cathode Fluorescent Lamp) is widely used as a light source of an illumination device such as a backlight of a liquid crystal display (LCD). In recent years, a light emitting diode (LED) has begun to be used as a light source of the lighting device.

An illuminating device using LEDs as light sources is configured by arranging LEDs that emit light in red (R), green (G), and blue (B), and arranging a large number of these sets. Further, an LED that emits a set of R, G, and B is used as one package, and many such packages are arranged side by side. Further, an LED package in which the LED emitting light to B is covered with a phosphor layer to convert the B light into yellow (Y) light so that white light is emitted by the color mixture of B and Y. Also comes to be used. Here, the LED package is a light-emitting device including a light-emitting diode (LED), and is disposed, for example, so that the lead frame is exposed inside the concave portion of the white resin case having the concave portion, and inside the concave portion. A light emitting diode (LED) is attached to an exposed lead frame, and these are electrically connected, and a sealing resin containing a sealing resin or a phosphor is formed in a recess so as to cover the semiconductor light emitting element. It is.
The illumination system used in the illumination apparatus includes a direct system in which a plurality of LED packages are arranged inside the illumination apparatus, for example, at intersections of the grid, and an end (edge) of the light guide plate made of acrylic or the like. There is an edge light system in which a plurality of LED packages are arranged.

  Patent Document 1 describes a technique for forming a linear light source that emits emitted light whose cross section is a line with a single LED for use in an edge light type planar light source or the like. Here, in a light emitting device in which an LED is sealed with a resin sealing body made of a translucent resin, a pair of parabolas falling symmetrically from both sides toward the center when viewed in the X-direction cross section of the resin sealing body. When viewed in the Y-direction cross section, the upper surface has a shape with a convex curve upward.

Japanese Patent No. 3905343

  However, a light emitting device (LED package) used in a direct illumination device is required to have a light emission characteristic different from the edge light method. Even in direct-type lighting devices, there is a demand for thinning (low profile) and a reduction in the number of light emitting devices (LED packages). That is, there is a need for a light emitting device controlled to emit light suitable for use in a direct lighting device and a lighting device using the light emitting device.

  The objective of this invention is providing the light-emitting device which controlled the light distribution of LED with the fluorescent substance layer which converts light, and an illuminating device using the same.

A light-emitting device to which the present invention is applied is formed by covering a light-emitting element on a substrate, a light-emitting element fixed on the substrate, and the surface opposite to the light-emitting element is depressed toward the light-emitting element. And a phosphor layer containing a fluorescent material and having a curved surface.
Then, the bottom of the curved surface of the phosphor layer is provided so as to face the light emitting element.
Further, the surface of the phosphor layer opposite to the light emitting element may be provided with a curved surface and an inclined surface that surrounds the curved surface and falls toward the light emitting element.

  Still further, a transparent resin layer formed on the substrate so as to cover the phosphor layer is further provided. And the external shape of a transparent resin layer can be shape | molded by the column shape. In the present invention, the outer shape may be a columnar shape, and includes shapes such as an elliptical column and an oval column, for example. Among other things, the outer shape can be characterized by a prismatic shape.

  From another point of view, an illumination device to which the present invention is applied is provided so as to face a light emitting device, a plurality of light emitting devices arranged to be connected to the circuit substrate, and emitting light. A diffusion plate that diffuses light incident from the light emitting device and emits the light from a surface opposite to the light emitting device, the light emitting device emitting light on the substrate, a light emitting element fixed on the substrate, and The surface opposite to the light emitting element is formed so as to cover the element, and includes a curved surface that is depressed toward the light emitting element, and a phosphor layer containing a fluorescent material.

  According to the present invention, it is possible to reduce the height of the lighting device and reduce the number of light emitting devices (LED packages).

It is a figure which shows the illuminating device in 1st Embodiment. It is a figure which shows the cross-sectional structure of the illuminating device in 1st Embodiment, and the light distribution characteristic of a light-emitting device. It is a figure explaining the structure of the light-emitting device in 1st Embodiment. It is a figure explaining the light distribution characteristic of the light-emitting device in 1st Embodiment. It is a figure which shows the result of the ray tracing for demonstrating the influence which the surface shape of a fluorescent substance layer has on the light distribution characteristic of a light-emitting device. It is a figure explaining the structure and light distribution characteristic of the light-emitting device in 2nd Embodiment. It is a figure explaining the structure and light distribution characteristic of the light-emitting device in 3rd Embodiment. It is a figure explaining the relationship between the structure of each light-emitting device in Examples 1-5 and a comparative example, and an evaluation result. It is a figure explaining the structure of the light-emitting device of a comparative example. It is a figure explaining the relationship between the radiation intensity and radiation angle (theta) in each light-emitting device of Example 1 and a comparative example. It is a figure explaining the relationship between the radiation intensity in the light-emitting device of Example 4, and radiation angle (theta). It is a figure explaining the relationship between the radiation intensity in the light-emitting device of Example 5, and radiation angle (theta).

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
(First embodiment)
FIG. 1 is a diagram illustrating an illumination device 10 according to the first embodiment.
In FIG. 1, the illumination device 10 is configured as a backlight of the LCD panel 20 as an example.

The lighting device 10 includes, for example, a circuit board 11 formed of glass epoxy or the like on which wiring is formed, a light emitting device 30 that includes LEDs and is mounted on the circuit board 11 and connected to the wiring, and a light emitting device of the circuit board 11 A diffusion plate 12 is provided to face the surface on which 30 is mounted. The diffusion plate 12 is arranged in parallel to the circuit board 11.
The light emitting devices 30 are regularly arranged on the circuit board 11 so as to be arranged, for example, at the intersections of the lattices. As described above, the illumination device 10 is a direct type.

  Although not shown, the LCD panel 20 includes a liquid crystal between a TFT substrate in which a thin film transistor (TFT) and a pixel electrode are formed for each pixel and a counter substrate in which a color filter and the like are formed for each counter electrode and pixel. The structure is sandwiched between. Furthermore, the LCD panel 20 includes polarizing plates on the outside of the TFT substrate and the counter substrate.

Since the light emitting device 30 is connected to the wiring formed on the circuit board 11, light is emitted (emitted) by supplying a current to the wiring.
The diffusing plate 12 diffuses light incident from the light emitting device 30 and emits light from a surface opposite to the incident surface. Thereby, the illuminating device 10 emits light.
Then, the LCD panel 20 controls the voltage applied to the liquid crystal for each pixel to form an image by transmitting or blocking the light incident from the illumination device 10.

FIG. 2 is a diagram illustrating a cross-sectional structure of the illumination device 10 and a light distribution characteristic of the light emitting device 30.
FIG. 2A is a cross-sectional view taken along line AA ′ of the illumination device 10 shown in FIG. FIG. 2A shows the circuit board 11, the light emitting device 30, and the diffusion plate 12. A plurality of light emitting devices 30 are regularly arranged on the circuit board 11.
Further, FIG. 2A shows light 41 emitted from the light emitting device 30 and light 42 emitted from the diffusion plate 12.

The light 41 emitted from the light emitting device 30 enters the diffusion plate 12 while spreading. The diffusion plate 12 emits the light 42 from the surface opposite to the surface on which the light 41 is incident.
It is desirable that the light 41 emitted from the light emitting device 30 is uniformly incident on the diffusion plate 12. Therefore, the number, arrangement, pitch, and the like of the light emitting devices 30 on the circuit board 11 are determined so that the light 41 emitted from the light emitting device 30 is uniformly incident on the diffusion plate 12.

  The diffusing plate 12 is made of, for example, a resin in which scatterers that do not absorb light are dispersed. The scatterer of the diffusion plate 12 reflects the light 41 incident on the diffusion plate 12 in various directions. Thereby, the diffusion plate 12 diffuses the light and controls the emission direction and the luminance distribution of the light from the diffusion plate 12.

FIG. 2B shows the definition of the light emission direction from the light emitting device 30. That is, a direction perpendicular to the diffusion plate 12 from the position of the light emitting device 30 is called a normal direction of the light emitting device 30 and is set to 0 °. The direction 90 ° to the right of the paper from the normal direction is 90 °, and the direction 90 ° to the left is −90 °. Further, an angle θ from the normal direction to the right 90 ° direction is defined as a radiation angle θ. Note that the angle θ toward the left 90 ° direction is −θ (not shown). The same applies to other surfaces including the normal line at the position of the light emitting device 30 other than the surface including the normal line at the position of the light emitting device 30 and the AA ′ line.
Here, the intensity of the light emitted from the light emitting device 30 is indicated by the radiant flux of light per solid angle in the light emitting direction outside the light emitting device 30, that is, the radiant intensity.
The dependence of the radiation intensity emitted by the light emitting device 30 on the radiation angle θ is referred to as the light distribution characteristic of the light emitting device 30.

  The light emitted from the light emitting device 30 at the radiation angle θ enters the diffusion plate 12 at the incident angle θ. For this reason, the radiant flux of light incident per unit area of the diffusion plate 12 is a value obtained by multiplying the radiant intensity by cos θ.

Here, regarding the method of expressing the light distribution characteristics, the light distribution characteristics in two special cases will be described.
FIG. 2C shows the light distribution characteristics when the light emitting device 30 is a light source with uniform diffusivity (in accordance with Lambert's cosine law). The light distribution characteristic is indicated by polar coordinates with the light emitting device 30 at the origin O. The horizontal axis represents the radiation intensity in the 90 ° direction on the right, the radiation intensity in the −90 ° direction on the left, and the vertical axis represents the radiation intensity in the normal direction (0 °) of the light emitting device 30. And between each axis | shaft, the radiation intensity in each direction is shown. The radiation intensity is shown as a relative value.

According to Lambert's cosine law, if the radiation intensity in the normal direction is I0, the radiation intensity Iθ at the radiation angle θ is expressed by Iθ = I0 cos θ. Therefore, the radiation intensity decreases as the radiation angle θ increases. The light distribution characteristic is a circle whose diameter is a line connecting the origin O of the light emitting device 30 and the vertical axis 1 in the normal direction, as shown in FIG.
For example, when this light is incident on the diffuser plate 12, the radiant flux incident per unit area of the diffuser plate 12 is obtained by multiplying the radiation intensity by cos θ as described above, and thus becomes cos ² θ times I0. . For this reason, the light emitted from the diffusing plate 12 is bright in the normal direction of the light emitting device 30, but the surroundings are dark.
For this reason, the illumination device 10 configured by arranging a plurality of light emitting devices 30 causes unevenness in the brightness of the light emitted from the diffusion plate 12 so that parts of the light emitted from the light emitting devices 30 overlap each other. Need to be configured so that there are few.

On the other hand, FIG. 2D shows the light distribution characteristics when the radiation intensity of the light emitting device 30 at the radiation angle θ is 1 / cos θ times the radiation angle 0 ° in the range of the radiation angles θ1 to −θ1. At this time, the line (radiation intensity envelope) connecting the radiation intensities at the radiation angle θ is parallel to the line connecting 90 ° and −90 ° in the range of the radiation angles θ1 to −θ1.
In this case, since the radiant flux per unit area on the diffusion plate 12 is obtained by multiplying the radiation intensity by cos θ as described above, the radiant flux per unit area of the diffusion plate 12 is constant. That is, within the radiation angles θ1 to −θ1, the light 42 emitted from the diffusion plate 12 has little unevenness in brightness.

As a result, the illuminating device 10 may be configured such that the light emitted from the respective light emitting devices 30 does not overlap each other. Thereby, the illumination device 10 with little unevenness in brightness can be configured by a small number of light emitting devices 30.
That is, in the direct lighting system 10, the light emitting device 30 having the light distribution characteristic shown in FIG.

  Note that the light emitted from the light emitting device 30 is totally reflected by the diffusion plate 12 when the radiation angle θ increases. Therefore, the maximum value that can be taken by the radiation angle θ <b> 1 may be up to a critical angle at which the light emitted from the light emitting device 30 is totally reflected by the diffusion plate 12.

FIG. 3 is an example of a diagram illustrating the structure of the light emitting device 30 according to the first embodiment. 3A is a plan view of the light emitting device 30, and FIG. 3B is a cross-sectional view taken along the line BB 'of FIG. 3A.
The light emitting device 30 emits light to a substrate on which wiring is formed, for example, a glass epoxy LED mounting substrate 31, and a light emitting element, for example B, fixed on the LED mounting substrate 31 with a conductive adhesive or a nonconductive adhesive. The LED 32 and a phosphor layer 33 containing a fluorescent material that emits light in Y by the B light emitted from the LED 32 are provided.

  The LED mounting substrate 31 is configured in a disk shape, for example. Although not shown, the LED mounting board 31 is provided with a terminal for connecting to the wiring formed on the circuit board 11. Furthermore, wiring for connecting to the terminals of the LEDs 32 is formed on the LED mounting substrate 31.

For example, the LED 32 is formed of a group III nitride semiconductor in which an n-type semiconductor layer, a light emitting layer, and a p-type semiconductor layer are epitaxially grown in this order on a sapphire substrate.
The LED 32 is fixed to the LED mounting substrate 31 on the surface opposite to the light emitting surface. Furthermore, the electrode (not shown) of the LED 32 and the wiring formed on the LED mounting substrate 31 are connected by, for example, a wire bond (not shown).

  The phosphor layer 33 is formed on the surface 31 a of the LED mounting substrate 31 so as to cover the LEDs 32 fixed to the LED mounting substrate 31. The phosphor layer 33 is a rubber-based resin containing about 10% by mass of a Yttrium Aluminum Garnet (YAG) phosphor having a size of about 10 μm, for example.

The phosphor layer 33 is surrounded by a front surface 33a, a back surface 33b, and a side surface 33c. The side surface 33 c of the phosphor layer 33 is formed in a columnar shape, continuing to the side surface of the LED mounting substrate 31. The back surface 33 b of the phosphor layer 33 is in contact with the front surface 31 a of the LED mounting substrate 31.
The surface 33a of the phosphor layer 33 is configured by a curved surface that drops toward the LED 32 in the central region, for example, a spherical surface having a curvature R. The curved surface is provided so that the bottom of the curved surface faces the LED 32.
Further, the surface 33a of the phosphor layer 33 is formed with an inclined surface that falls in a conical shape toward the LED 32 so as to surround the curved surface. That is, the phosphor layer 33 is configured as a rotating body that passes through the center of the LED 32 and has an XX ′ line that is a perpendicular to the LED 32 as a rotation axis.

The distance h1 is from the surface 31a of the LED mounting substrate 31 to the point where the point T corresponding to the apex of the cone formed by the surface 33a of the phosphor layer 33 and the line XX ′ intersect. Similarly, the distance h2 is from the surface 31a of the LED mounting substrate 31 to the center S of the curvature R of the curved surface. Furthermore, the distance h3 is from the surface 31a of the LED mounting substrate 31 to the thickest part on the outer periphery of the phosphor layer 33.
Further, the angle formed by the inclined surface is the central angle φ. The LED mounting substrate 31 has a diameter d1.
The light emitting device 30 has, for example, R = 0.680 mm, h1 = 0.653 mm, h2 = 1.300 mm, h3 = 1.256 mm, φ = 1136 °, d1 = 2.983 mm.

In the light emitting device 30, the current is supplied to the LED 32 from the wiring formed on the circuit board 11 through the wiring formed on the LED mounting substrate 31, so that the LED 32 emits (emits light) B light. The phosphor layer 33 emits (emits) Y light by the B light.
That is, in the light emitting device 30 according to the first embodiment, the B light emitted from the LED 32 and the Y light emitted from the phosphor layer 33 by the B light are mixed to emit white light.

FIG. 4 is a diagram for explaining light distribution characteristics obtained by simulation of the light emitting device 30 according to the first embodiment.
FIG. 4A shows the light distribution characteristics when a hemispherical phosphor layer 33 is provided as a comparative example in the light emitting device 30. The light distribution characteristic of FIG. 4A is similar to the light distribution characteristic shown in FIG. That is, the light emitting device 30 provided with the hemispherical phosphor layer 33 exhibits light distribution characteristics according to Lambert's cosine law. The light distribution characteristics in FIG. 4A are characteristics on the plane including the normal line of the LED 32 and the BB ′ line in FIG. 3A, but the same is true for other planes including the normal line of the LED 32. The light distribution characteristics of are shown.

  On the other hand, FIG. 4B shows the light distribution characteristics of the light emitting device 30 provided with the phosphor layer 33 in the first embodiment shown in FIG. The envelope of the radiation intensity of the light emitting device 30 is substantially parallel to a line connecting 90 ° and −90 ° when the radiation angle θ is in the range of −22.5 ° to 22.5 °. This light distribution characteristic is close to the light distribution characteristic shown in FIG. The light distribution characteristic in FIG. 4B is a characteristic on the plane including the line XX ′ in FIG. 3B and the line BB ′ in FIG. Other surfaces including the line show similar characteristics.

Next, the reason why the light emitting device 30 in the first embodiment produces the light distribution characteristic shown in FIG. 4B will be described.
In the first embodiment, it is required that the radiation intensity of the light emitting device 30 is higher as the radiation angle θ is larger.
The phosphor layer 33 converts B light emitted from the LED 32 into Y light and also functions as a lens. Therefore, if the shape of the phosphor layer 33 is changed, the light distribution of the light emitted from the phosphor layer 33 can be controlled.

As a method of increasing the radiation intensity of the light emitting device 30 as the radiation angle θ is larger, it is conceivable that the upper surface of the phosphor layer 33 is a concave lens. It is also conceivable that the upper surface of the phosphor layer 33 is conical so that it has a V shape in which two prisms are arranged in a cross section.
FIG. 5 is a diagram showing the result of ray tracing for explaining the influence of the surface shape of the phosphor layer 33 on the light distribution characteristics of the light emitting device 30. Here, in order to clarify the influence of the surface shape of the phosphor layer 33, a transparent resin layer was used instead of the phosphor layer 33.

FIG. 5A is a diagram showing the result of ray tracing in the transparent resin layer 34 having the thinnest concave lens shape on the upper surface with respect to the LED 32.
An LED 32 is provided on the LED mounting substrate 31, and a concave lens-shaped transparent resin layer 34 is provided on the LED mounting substrate 31 so as to cover the LED 32.
Looking at the result of ray tracing, in this structure, the light emitted from the LED 32 is slightly out in the normal direction of the LED 32.

On the other hand, FIG. 5B is a diagram showing the result of ray tracing in the case of the transparent resin layer 35 having the thinnest conical upper surface with respect to the LED 32.
An LED 32 is provided on the LED mounting substrate 31, and a transparent resin layer 35 having a conical surface is provided on the LED mounting substrate 31 so as to cover the LED 32.
Looking at the result of ray tracing, in this structure, the number of rays emitted from the LED 32 is small in the normal direction of the LED 32 and is excessively emitted to the side of the LED 32.

From the above, as shown in the first embodiment, the surface 33a of the phosphor layer 33 has a curved surface portion facing the LED 32, and the surrounding portion of the curved surface is inclined toward the normal line of the LED 32. A conical configuration is preferable.
Note that the result of ray tracing shown in FIG. 5 does not consider the effect of light scattering by the fluorescent material in the phosphor layer 33 or the effect of light emitted by the phosphor. Therefore, the light distribution characteristic shown in FIG. 4B is obtained by adding these effects, and is not only due to the lens effect of the phosphor layer 33.

(Second Embodiment)
FIG. 6 is a diagram illustrating the structure and light distribution characteristics of the light emitting device 30 according to the second embodiment. 6A is a plan view of the light emitting device 30, and FIG. 6B is a cross-sectional view taken along the line CC 'of FIG. 6A. FIG. 6C shows light distribution characteristics obtained by simulation of the light emitting device 30.
The light emitting device 30 of the second embodiment includes, for example, a glass epoxy LED mounting substrate 51 on which wiring is formed, and a light emitting element fixed on the LED mounting substrate 51 with a conductive adhesive or a nonconductive adhesive, For example, an LED 32 that emits light to B, a phosphor layer 33 that emits light to Y by B light emitted from the LED 32, and a transparent resin layer 52 that is formed so as to cover the phosphor layer 33 are provided.
The LED 32 and the phosphor layer 33 are the same as those in the light emitting device 30 in the first embodiment.

The transparent resin layer 52 is, for example, a rubber-based resin, and is the same as the resin used for the phosphor layer 33. The transparent resin layer 52 has a cylindrical shape with the same diameter d2 as the diameter d2 of the LED mounting substrate 51, and the surface 52a thereof is flat. The transparent resin layer 52 has a thickness t1 from the surface 51a of the LED mounting substrate 51. For example, d2 = 4.465 mm and t1 = 1.920 mm.
The light emitting device 30 in the second embodiment is equivalent to a structure in which the light emitting device 30 in the first embodiment is covered with a columnar transparent resin layer 52.

As shown in FIG. 6C, the envelope of the radiation intensity of the light emitting device 30 is parallel to the line connecting -90 ° and 90 ° when the radiation angle θ is in the range of −45 ° to 45 °. This characteristic has a wider range of radiation angles than the characteristic shown in FIG.
The light distribution characteristic in FIG. 6C is a characteristic in a plane including the line XX ′ in FIG. 6B and the line CC ′ in FIG. 6A. Other surfaces including the line show similar characteristics.

(Third embodiment)
FIG. 7 is a diagram illustrating the structure and light distribution characteristics of the light emitting device 30 according to the third embodiment. 7A is a plan view of the light emitting device 30, and FIG. 7B is a cross-sectional view taken along the line DD 'in FIG. 7A. FIG. 7C shows the light distribution characteristics in the directions of the DD ′ line and the EE ′ line of FIG. 7A obtained by simulation of the light emitting device 30.

The light emitting device 30 according to the third embodiment includes, for example, a glass epoxy LED mounting substrate 61 on which wiring is formed, and a light emitting element fixed on the LED mounting substrate 61 with a conductive adhesive or a nonconductive adhesive, For example, an LED 32 that emits light at B, a phosphor layer 33 that emits light at Y by the B light emitted from the LED 32, and a transparent resin layer 62 that is formed so as to cover the phosphor layer 33 are provided.
The LED mounting substrate 61 has a rectangular plate shape with side lengths d3 and d4. The LED 32 and the phosphor layer 33 are the same as those in the light emitting device 30 in the first embodiment. The transparent resin layer 62 is, for example, a rubber-based resin and is the same as the resin used for the phosphor layer 33. The transparent resin layer 62 has a rectangular prismatic shape with side lengths d3 and d4, a thickness t2 from the surface 61a of the LED mounting substrate 61, and a flat surface 62a, like the LED mounting substrate 61. For example, d3 = d4 = 4.465 mm and t2 = 2.080 mm.
The light emitting device 30 in the third embodiment is equivalent to a structure in which the light emitting device 30 in the first embodiment is covered with a prismatic transparent resin layer 62.

  As shown in FIG. 7C, the envelope of the radiation intensity of the light emitting device 30 is − in both the DD ′ line and the EE ′ line in the range of the radiation angle θ of −45 ° to 45 °. It is parallel to the line connecting 90 ° and 90 °. This indicates that the radiant flux incident per unit area of the diffusion plate 12 is constant in a rectangular range. For this reason, in the illuminating device 10, what is necessary is just to arrange | position the light-emitting device 30 so that it may lay down a tile so that the light radiate | emitted from each light-emitting device 30 may not overlap. For this reason, if the light-emitting device 30 of 3rd Embodiment is used, it can arrange most efficiently.

In addition, although the surface 33a of the fluorescent substance layer 33 and the part which LED32 opposes were made into the spherical surface of the curvature R as an example, it may be the curved surface which fell toward LED32.
The center angle φ formed by the conical inclined surface around the curved surface is 136 ° as an example, but may be 30 ° or more and less than 180 °. Preferably, the angle is 130 ° to 140 °. If the central angle φ is smaller than these values, the light becomes stronger in the range where the radiation angle θ is small. On the other hand, when the central angle φ is larger than these values, the light becomes strong in the range where the radiation angle θ is large.

  Further, the resin of the phosphor layer 33 in which the fluorescent substance is dispersed is not limited to the rubber-based resin, and a resin-based resin, a silicone material, or the like can be used.

  In addition, the transparent resin layer 62 formed so as to cover the phosphor layer 33 has a columnar shape or a prismatic shape, but may have a columnar shape with a recessed side surface. That is, the side surface of the columnar transparent resin layer 62 may be used by being deformed according to the light distribution characteristics.

Next, examples of the present invention will be described, but the present invention is not limited to the examples.
The inventor manufactured the light emitting device 30 for each of the first embodiment, the second embodiment, and the third embodiment. The light distribution characteristics, light emission efficiency, and extraction efficiency of the light emitting device 30 and the light emitting device 30 of the comparative example were examined.
FIG. 8 is a diagram illustrating the relationship between the configuration of each light emitting device 30 and the evaluation results in Examples 1 to 5 and the comparative example.

Each light-emitting device 30 of Examples 1 to 3 has the configuration described in the first embodiment. The light emitting device 30 of Example 4 has a configuration using a cylindrical transparent resin layer 52 corresponding to the second embodiment. The light emitting device 30 of Example 5 has a configuration using a prismatic transparent resin layer 62 corresponding to the third embodiment.
The phosphor layers 33 of the light emitting devices 30 of Examples 1 to 5 have the shapes exemplified in the first embodiment except for the matters described below.
Furthermore, the transparent resin layer 52 of the light emitting device 30 of Example 4 has the shape exemplified in the second embodiment. Similarly, the transparent resin layer 62 of the light emitting device 30 of Example 5 has the shape exemplified in the third embodiment.

  On the other hand, in the light emitting device 30 of the comparative example, as described below, the LED 32 is attached to the inside of the concave portion 71a of the white resin case 70 (see FIG. 9 to be described later) having the concave portion 71a (see FIG. 9 to be described later). Is formed by forming a phosphor layer 75 (see FIG. 9 described later) in the recess 71a.

Here, the light emitting device 30 of the comparative example will be described.
FIG. 9 is a diagram illustrating the structure of a light emitting device 30 of a comparative example. 9A is a top view of the light emitting device 30, and FIG. 9B is a cross-sectional view taken along the line FF ′ of FIG. 9A. In the light emitting device 30 of the comparative example, the LED 32 is mounted on the white resin case 70.
The white resin case 70 includes a resin container 71 having a recess 71 a having a wall surface 81 that rises so as to expand toward the upper side, an anode lead part 72 including a lead frame integrated with the resin container 71, and a cathode lead. And a phosphor layer 75 provided to cover the recess 71a. And LED32 is being fixed to the bottom face 80 which has the circular shape of the recessed part 71a of the white resin case 70. As shown in FIG. The phosphor layer 75 is provided so as to cover the LED 32 as well.

The resin container 71 of the white resin case 70 is formed by injection-molding a thermoplastic resin containing a white pigment in a metal lead portion including the anode lead portion 72 and the cathode lead portion 73.
In the LED 32, the p electrode is connected to the anode lead portion 72 and the n electrode is connected to the cathode lead portion 73 via a bonding wire (not shown) on the cathode lead portion 73 exposed on the bottom surface 80. The anode lead portion 72 and the cathode lead portion 73 are respectively bent and disposed on the back side of the resin container 71.
The light emitting device 30 of the comparative example has a horizontal d5 of 3.5 mm and a vertical d6 of 2.8 mm in FIG.

  The LED 32 emits B light by causing a current to flow through the LED 32 using the anode lead portion 72 as a positive electrode and the cathode lead portion 73 as a negative electrode. The phosphor layer 75 emits Y light by the B light emitted from the LED 32. In the light emitting device 30 of the comparative example, as in Examples 1 to 5, the B light emitted from the LED 32 and the Y light emitted from the phosphor layer 75 by the B light are mixed to produce white light. Is emitted.

Now, returning to FIG. 8, the items of the configuration shown in FIG. 8 will be described.
“Number of LED chips” indicates the number of LED chips mounted per light emitting device 30 (package). The so-called number of LED chips per package. The number of chips of 3 indicates that the LED 32 of the light emitting device 30 is configured by three LED chips, that is, the light emitting device 30 is a 3 in 1 package.
LED32 of each light-emitting device 30 of Examples 1-5 is comprised by three LED chips. The LED 32 of the light emitting device 30 of the comparative example is composed of one LED chip. In any case, the LED 32 emits B light having a peak near 448 nm.
The next “LED radiant flux” indicates the radiant flux of the LED 32 in mW.
The “phosphor (content ratio)” is the phosphor used for the phosphor layer 33 (Examples 1 to 5) and the phosphor layer 75 (comparative example) that emits light to Y by the B light emitted from the LED 32. The type and content rate are shown. Here, Y450C (manufactured by INTEMATIX) and EY425No. Two types of phosphors 2 (manufactured by INTERMATIX) were used. The content is in the range of 8% by mass to 12% by mass.

  “Transparent resin” indicates the presence or absence of the transparent resin layer 52 or the transparent resin layer 62 of the light emitting device 30. As described above, in Example 4, the columnar transparent resin layer 52 is used corresponding to the second embodiment. Further, in Example 5, a prismatic transparent resin layer 62 is used corresponding to the third embodiment. In other Examples 1 to 3 and the comparative example, neither the transparent resin layer 52 nor the transparent resin layer 62 is used.

Next, the evaluation result will be described.
In FIG. 8, as evaluation results of the respective light emitting devices 30 in Examples 1 to 5 and the comparative example, the half value angle that is the range of the radiation angle θ in which the radiation intensity is 1/2 or more of the peak, the luminous efficiency, and the CIE1931 The chromaticity coordinates in the color system and the extraction efficiency are shown.
The extraction efficiency referred to here is a value obtained by dividing the radiant flux from each light emitting device 30 in Examples 1 to 5 and the comparative example by the respective LED radiant flux, and does not consider a loss in the LED chip.
Hereinafter, the evaluation results shown in FIG. 8 will be described while sequentially explaining the relationship between the radiation intensity and the radiation angle θ in each of the light emitting devices 30 in Examples 1 to 5 and the comparative example.

  FIG. 10 is a diagram illustrating the relationship between the radiation intensity and the radiation angle θ in each light emitting device 30 of Example 1 and the comparative example. FIG. 10A shows the relationship between the radiation intensity and the radiation angle θ, with the radiation angle θ as the horizontal axis and the radiation intensity as the vertical axis. On the other hand, FIG. 10B shows the relationship between the radiation intensity and the radiation angle θ in polar coordinates (polar coordinate notation). In each case, the radiation intensity is shown as a relative value.

First, a comparative example will be described. The light emitting device 30 of the comparative example includes an LED 32 (consisting of one LED chip) having a radiant flux of 14.26 mW, and contains 12% by mass of Y450C as the phosphor of the phosphor layer 75. The remainder of the phosphor layer 75 excluding the phosphor is SCR-1011 (manufactured by Shin-Etsu Chemical Co., Ltd.), which is a silicone rubber resin.
FIG. 10A shows the light distribution characteristic in the cross section taken along the line FF ′ shown in FIG. 9 as the orientation characteristic of the light emitting device 30 of the comparative example. In the light emitting device 30 of the comparative example, the radiation intensity decreases rapidly as the radiation angle θ approaches 0 ° to 90 ° or −90 °. As can be seen from FIG. 10B, in the polar coordinate notation, the radiation intensity indicates a vertically long envelope.
As shown in the comparative example of FIG. 10A, the half-value angle shown in FIG. 8 is the radiation angle θ (the left and right radiation angles θ across 0 °) at which the radiation intensity becomes ½ of the peak value. Range (difference). The half-value angle of the light emitting device 30 of the comparative example was 110 °.
Further, in the light emitting device 30 of the comparative example, the luminous efficiency was 88 lm / W, and the chromaticity coordinates were x = 0.34 and y = 0.37. The take-out efficiency was 82.1%.

On the other hand, the light-emitting device 30 of Example 1 includes an LED 32 (consisting of three LED chips) having a radiant flux of 19 mW, and contains 8% by mass of Y450C as the phosphor of the phosphor layer 33. The remainder of the phosphor layer 33 excluding the phosphor is KER-2500 (manufactured by Shin-Etsu Chemical Co., Ltd.), which is a silicone rubber resin.
In FIG. 10A, as the orientation characteristics of the light emitting device 30 of Example 1, the light distribution characteristics (shown by 0 ° plane) in the cross section along the line BB ′ shown in FIG. The orientation characteristics (shown by a 90 ° plane) in a cross section taken along a line orthogonal to the line are shown. And also in the light-emitting device 30 of Example 1, the radiation intensity decreases as the radiation angle θ approaches 0 ° to 90 ° or −90 °. However, even if the radiation angle θ is 90 ° or −90 °, it does not become zero. That is, in the light emitting device 30 of Example 1, it is shown that light is emitted also in the lateral direction (radiation angle ± 90 °) of the light emitting device 30. The rate of decrease is moderate compared to the light emitting device 30 of the comparative example. The half-value angle of the light-emitting device 30 of Example 1 is 148 °, which is about 40 ° larger than the half-value angle of 110 ° of the light-emitting device 30 of the comparative example.
Further, as shown in FIG. 10B, in the polar coordinate notation, the envelope of the radiation intensity of the light emitting device 30 of the first embodiment is a horizontally wide ellipse. In FIG. 10B, the envelope of the radiation intensity of the light emitting device 30 of Example 1 is wider in the left-right direction than the envelope of the radiation intensity of the light emitting device 30 of the comparative example.

As described above, the light emitting device 30 of Example 1 shows that light spreads in the lateral direction (radiation angle ± 90 °) as compared with the light emitting device 30 of the comparative example.
And the envelope of the radiation intensity of the light emitting device 30 of Example 1 shown in FIG. 10B is close to the envelope of the radiation intensity of FIG. 4B obtained by simulation in the first embodiment. Therefore, the characteristics of the light emitting device 30 of Example 1 indicate that the light emitting device 30 of the first example can be realized.

  In addition, in the light-emitting device 30 of Example 1 shown to Fig.10 (a), the light distribution characteristic in a 0 degree surface and the light distribution characteristic in a 90 degree surface seem to have shifted | deviated with respect to the radiation angle (theta). This is due to an installation error of the light emitting device 30 in the measurement of the orientation characteristics. As can be seen from the configuration of the light emitting device 30 of the first embodiment shown in FIG. 3A, the cross section taken along the line BB ′ and the cross section taken along the line perpendicular to the BB ′ line are structures. Since they are the same, there is almost no difference between the light distribution characteristic shown at 0 ° and the light distribution characteristic shown at 90 °. The same applies to FIG. 10B in polar coordinate notation.

The light-emitting device 30 of Example 2 and 3 is the light-emitting device 30 in 1st Embodiment similarly to the light-emitting device 30 of Example 1. FIG. The light emitting device 30 of Example 2 includes an LED 32 (consisting of three LED chips) having a radiant flux of 19 mW, and contains 10% by mass of Y450C as a phosphor of the phosphor layer 33. On the other hand, the light emitting device 30 of Example 3 includes an LED 32 (comprising three LED chips) having a radiant flux of 21 mW, and EY4254No. 2 is contained in an amount of 10% by mass. In all cases, the remainder of the phosphor layer 33 excluding the phosphor is KER-2500 (manufactured by Shin-Etsu Chemical Co., Ltd.), which is a silicone rubber resin.
Although not shown, the light emitting devices 30 of Examples 2 and 3 exhibit the same alignment characteristics as the light emitting device 30 of Example 1. The light emitting device 30 of Example 2 had a half-value angle of 148 ° and a luminous efficiency of 107 lm / W (chromaticity coordinates x = y = about 0.3). In addition, the light-emitting device 30 of Example 3 had a half-value angle of 155 °, a light emission efficiency of 112 lm / W, and a take-out efficiency of 70.7%.

That is, the light-emitting device 30 of Examples 2 and 3 has a larger half-value angle than the light-emitting device 30 of the comparative example and can emit light in a wide range of the emission angle θ, as with the light-emitting device 30 of Example 1. You can see that In Examples 1 and 2 and Example 3, the half-value angle is different from 148 ° and 155 °, which is considered to be due to the type of the phosphor used, the variation in the shape of the light emitting device 30, and the like. .
On the other hand, the extraction efficiency of the light emitting device 30 of Example 3 is 70.7%, which is smaller than the extraction efficiency of 82.1% of the light emitting device 30 of the comparative example. As shown in FIG. 3, since the side surface of the phosphor layer 33 is cylindrical, the light incident on the side surface of the cylinder at a total reflection angle is repeatedly reflected and confined on the side surface of the cylinder. This is thought to be due to the difficulty of taking it out. On the other hand, in the light emitting device 30 of the comparative example, the inner side of the white resin case 70 is configured by the wall surface 81 that rises so as to expand toward the upper side, so that it is considered that light is not easily trapped.

  FIG. 11 is a diagram illustrating the relationship between the radiation intensity and the radiation angle θ in the light emitting device 30 according to the fourth embodiment. FIG. 11A shows the relationship between the radiation intensity and the radiation angle θ, with the radiation angle θ as the horizontal axis and the radiation intensity as the vertical axis. On the other hand, FIG. 11B shows the relationship between the radiation intensity and the radiation angle θ in polar coordinates (polar coordinate notation). In each case, the radiation intensity is shown as a relative value. Note that FIG. 11A also shows the alignment characteristics of the comparative example described in FIG.

The light emitting device 30 of Example 4 is the light emitting device 30 of the second embodiment, and includes a cylindrical transparent resin layer 52. The number of LED chips of the LED 32, the LED radiant flux of the LED 32, the phosphor (EY425 No. 2) used for the phosphor layer 33, and the content thereof are the same as those of the light emitting device 30 of the third embodiment.
The transparent resin layer 52 is KER-2500 (manufactured by Shin-Etsu Chemical Co., Ltd.), like the remaining silicone rubber resin excluding the phosphor of the phosphor layer 33.

  11 (a) and 11 (b), the light distribution characteristics (shown by 0 ° plane) along the line CC ′ in FIG. 6 (a) and the cross section along the line orthogonal to the CC ′ line. Orientation characteristics (indicated by a 90 ° plane). The radiant intensity of the light emitting device 30 of Example 4 is maximized when the radiation angle θ is around ± 20 °, and slightly decreases around 0 °. The radiation intensity decreases as the radiation angle θ approaches 20 ° to 90 ° or −20 ° to −90 °, but the rate of the decrease is more gradual than that of the light emitting device 30 of the first embodiment. The full width at half maximum of the light emitting device 30 of Example 4 is 159 °, which is larger than those in Examples 1 to 3 (148 ° and 155 °).

The envelope of the radiation intensity in the polar coordinate notation of FIG. 11B is further expanded in the left-right direction as compared with the case of Example 1 shown in FIG. The envelope of the radiant intensity in FIG. 11B has a shape close to the envelope of the radiant intensity in FIG. 6C obtained by simulation in the second embodiment. Note that the radiation intensity is small when the radiation angle θ is in the ± 45 ° direction because the light emitting device 30 of Example 4 has the side surface and the top surface of the cylindrical transparent resin layer 52 shown in FIG. This is probably because the shape was not a steep shape (right angle) at the boundary, but a rounded corner.
Therefore, the characteristics shown by the light emitting device 30 of Example 4 indicate that the light emitting device 30 of the second example can be realized.

  Note that the light distribution characteristic on the 0 ° plane and the light distribution characteristic on the 90 ° plane appear to be shifted with respect to the radiation angle θ. This is due to an installation error of the light emitting device 30 in the measurement of orientation characteristics. As can be seen from the configuration of the light emitting device 30 of the second embodiment shown in FIG. 6A, the cross section taken along the line CC ′ and the cross section taken along the line perpendicular to the line CC ′ are structures. Since they are equivalent to each other, there is almost no difference between the light distribution characteristics at 0 ° and the light distribution characteristics at 90 °. The same applies to FIG. 11B expressed in polar coordinates.

  The light emitting device 30 of Example 4 has a luminous efficiency of 112 lm / W. However, the extraction efficiency is 68.4%, which is smaller than that of Example 3 and the comparative example. As shown in FIGS. 6A and 6B, the extraction efficiency is small because the transparent resin layer 52 has a cylindrical shape, so that the light incident on the side surface of the cylinder at the total reflection angle is the side surface of the cylinder. This is thought to be due to repeated reflection and confinement and difficulty in taking it out.

  FIG. 12 is a diagram illustrating the relationship between the radiation intensity and the radiation angle θ in the light emitting device 30 of the fifth embodiment. FIG. 12 (a) shows the relationship between the radiation intensity and the radiation angle θ, with the radiation angle θ as the horizontal axis and the radiation intensity as the vertical axis. On the other hand, FIG. 12B shows the relationship between the radiation intensity and the radiation angle θ in polar coordinates (polar coordinate notation). In each case, the radiation intensity is shown as a relative value. FIG. 12A also shows the alignment characteristics of the comparative example described in FIG.

The light emitting device 30 of Example 5 is the light emitting device 30 of the third embodiment, and includes a prismatic transparent resin layer 62 having a square top surface. The number of LED chips of the LED 32, the LED radiant flux of the LED 32, the phosphor (EY425 No. 2) used for the phosphor layer 33, and the content thereof are the same as those of the light emitting device 30 of the third embodiment.
The transparent resin layer 62 is KER-2500 (manufactured by Shin-Etsu Chemical Co., Ltd.), like the remaining silicone rubber resin excluding the phosphor of the phosphor layer 33.

12 (a) and 12 (b), the light distribution characteristics (shown by the 0 ° plane) in the cross section along the line DD 'in FIG. 7 (a) and the line orthogonal to the DD' line. The orientation characteristics in the cross section (shown by the 90 ° plane) and the orientation characteristics in the cross section along the line inclined by 40 ° with respect to the DD ′ line (shown by the 40 ° plane) are shown. The line inclined by 40 ° with respect to the DD ′ line is close to the EE ′ line inclined by 45 ° with respect to the DD ′ line in FIG.
As shown in FIG. 12A, in the orientation characteristics at the 0 ° plane and the orientation characteristics at the 90 ° plane, the radiant intensity is the maximum when the radiation angle θ is around ± 30 °, and the radiation angle θ is 0 °. In the vicinity, the radiation intensity is slightly reduced. As the radiation angle θ approaches 30 ° to 90 ° or −30 ° to −90 °, it gradually decreases. The orientation characteristics on the 0 ° plane and the orientation characteristics on the 90 ° plane are almost the same. As can be seen from FIG. 7A, since the upper surface of the prismatic transparent resin layer 62 is square, the cross section taken along the line DD ′ and the cross section taken along the line perpendicular thereto are structurally equivalent. It is.

On the other hand, in the orientation characteristics on the 40 ° plane, the radiation intensity is maintained to be larger up to a larger range of the radiation angle θ (the absolute value of θ) than the orientation characteristics on the 0 ° plane and the 90 ° plane. That is, the full width at half maximum of the orientation characteristic on the 40 ° plane is wider than the orientation characteristic on the 0 ° plane and the orientation characteristic on the 90 ° plane. As shown in FIG. 8, the full width at half maximum on the 0 ° plane is 157 °, but the full width at half maximum on the 40 ° plane is 162 °.
This also applies to the polar coordinate notation shown in FIG. 12 (b). The envelope of the radiation intensity at the 40 ° plane is more lateral than the envelope of the radiation intensity at the 0 ° plane and the 90 ° plane. It has spread.

The envelope of the radiation intensity of each of the 0 ° plane, 90 ° plane, and 40 ° plane shown in FIG. 12B is DD ′ in FIG. 7C obtained by simulation in the third embodiment. And a shape close to the envelope of the radiation intensity indicated by EE ′. Note that the difference between the lateral spread of the radiation intensity envelope on the 40 ° plane and the lateral spread of the 0 ° or 90 ° radiation intensity envelope is indicated by DD ′ in FIG. 7C. The difference between the horizontal spread of the envelope of radiation intensity and the spread of the envelope of radiation intensity indicated by EE ′ in the horizontal direction is smaller than that of EE ′ being 45 ° with respect to DD ′. On the other hand, the 40 ° plane is considered to be 40 ° shallow.
In addition, in the envelope of the radiation intensity on the 0 °, 90 °, and 40 ° planes shown in FIG. 12B, the radiation intensity decreases when the radiation angle θ is around ± 45 °. This is probably because the boundary between the upper surface and the side surface of the resin layer 62 does not have a steep shape (right angle), but has a rounded corner.

Furthermore, the light-emitting device 30 of Example 5 has chromaticity coordinates x = y = about 0.3 and luminous efficiency of 136 lm / W. The take-out efficiency is 96.1%, which is higher than those in Examples 3 and 4 and the comparative example. This is because the transparent resin layer 62 is formed in a prismatic shape, so that even light incident on the side surface of the prism at a total reflection angle can be extracted from the other side surface, and the light is confined in the transparent resin layer 62. It is thought that it is because it is hard to be done.
Therefore, the light emitting device 30 provided with the prismatic transparent resin layer 62 is most preferable because it has a large half-value angle and high extraction efficiency.

DESCRIPTION OF SYMBOLS 10 ... Illuminating device, 11 ... Circuit board, 12 ... Diffusing plate, 20 ... LCD panel, 30 ... Light-emitting device, 31, 51, 61 ... LED mounting board, 32 ... LED, 33, 75 ... Phosphor layer, 34, 35 , 52, 62 ... transparent resin layer, 70 ... white resin case, 71 ... resin container

Claims (7)

A substrate,
A light-emitting element fixed on the substrate;
The light-emitting element is formed on the substrate so as to cover the light-emitting element, and a surface opposite to the light-emitting element includes a curved surface that is depressed toward the light-emitting element, and includes a phosphor layer containing a fluorescent material. Light-emitting device.   The light emitting device according to claim 1, wherein the bottom surface of the curved surface of the phosphor layer is provided so as to face the light emitting element. The surface of the phosphor layer opposite to the light emitting element is
The curved surface;
The light-emitting device according to claim 2, further comprising an inclined surface that surrounds the curved surface and falls toward the light-emitting element. The light-emitting device according to claim 1, further comprising a transparent resin layer formed on the substrate so as to cover the phosphor layer.   The light emitting device according to claim 4, wherein an outer shape of the transparent resin layer is formed in a columnar shape.   The light emitting device according to claim 5, wherein an outer shape of the transparent resin layer is formed in a prismatic shape. A circuit board;
A plurality of light emitting devices arranged to be connected to the circuit board and emitting light;
A diffusion plate that is provided facing the light emitting device, diffuses light incident from the light emitting device, and emits the light from a surface opposite to the light emitting device;
With
The light emitting device
A substrate,
A light-emitting element fixed on the substrate;
The light-emitting element is formed on the substrate so as to cover the light-emitting element, and a surface opposite to the light-emitting element is provided with a curved surface that is depressed toward the light-emitting element, and includes a phosphor layer containing a fluorescent material. Lighting device.

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