JP7161330B2 - light emitting device - Google Patents

Description

The present invention relates to a light-emitting device including light-emitting elements such as light-emitting diodes.

Conventionally, there has been known a light-emitting device that combines a light-emitting element that emits light having a predetermined wavelength (emission color) and a wavelength converter that converts the wavelength of light emitted from the light source (for example, Patent Document 1, etc.). ).

JP 2010-219324 A

In some cases, light emitting devices are required not only to emit light of high intensity (that is, to have high output) but also to have a clear boundary between light and dark (that is, to have high contrast). In this case, the light-emitting device is required to be configured so as to emit high-power light from a specific region and not to emit light from other regions.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a light emitting device having a simple structure and high output and high contrast.

A light-emitting device according to the present invention comprises a substrate, a light-emitting element arranged on the substrate, a light-transmitting member arranged on the light-emitting element, a frame arranged on the substrate so as to surround the light-transmitting member, and a substrate. a coating disposed thereon, covering the side surface of the light-transmitting member and the top surface of the frame, and having an upper surface exposed to the outside, wherein the coating is particles composed of a plurality of particles dispersed in the coating. wherein the particles in the particle group comprise a plurality of titanium oxide particles or zinc oxide particles dispersed in the vicinity of the upper surface of the coating and having a portion within each particle having a smaller bandgap than other portions. Characterized by

A light-emitting device according to the present invention includes a substrate, a light-emitting element arranged on the substrate, a frame arranged on the substrate so as to surround the light-emitting element, and a frame arranged on the substrate and configured to cover the side surfaces and the frame of the light-emitting element. a coating that covers the upper surface of the body and has an upper surface exposed to the outside, the coating having a particle group composed of a plurality of particles dispersed in the coating, and the particles of the particle group comprising the coating It is characterized by comprising a plurality of titanium oxide or zinc oxide particles dispersed in the vicinity of the upper surface of the body and having a portion within each particle having a smaller bandgap than other portions.

1 is a cross-sectional view of a light emitting device according to Example 1. FIG. 1 is a top view of a light emitting device according to Example 1. FIG. 1 is an enlarged cross-sectional view of a light emitting device according to Example 1. FIG. 4 is a cross-sectional view of particles in a coating in the light-emitting device according to Example 1. FIG. 4A to 4C are diagrams illustrating a method for manufacturing the light emitting device according to Example 1; 4A to 4C are diagrams illustrating a method for manufacturing the light emitting device according to Example 1; 4A to 4C are diagrams illustrating a method for manufacturing the light emitting device according to Example 1; FIG. 4 is a diagram schematically showing light paths in the light-emitting device according to Example 1; FIG. 10 is a cross-sectional view of a light-emitting device according to Modification 1 of Example 1; FIG. 10 is a cross-sectional view of a light-emitting device according to Modification 2 of Example 1; FIG. 11 is a cross-sectional view of a light-emitting device according to Modification 3 of Example 1; FIG. 10 is a cross-sectional view of a light-emitting device according to Modification 4 of Example 1; FIG. 11 is a cross-sectional view of a light-emitting device according to Modification 5 of Example 1; FIG. 10 is a cross-sectional view of a light emitting device according to Example 2; FIG. 10 is a top view of a light emitting device according to Example 2; FIG. 10 is an enlarged cross-sectional view of a light emitting device according to Example 2; FIG. 10 is a diagram showing light output from a light emitting device according to Example 2; FIG. 11 is a cross-sectional view of a light emitting device according to Example 3; FIG. 11 is a top view of a light emitting device according to Example 3;

Examples of the present invention will be described in detail below.

FIG. 1A is a cross-sectional view of a light emitting device 10 according to Example 1. FIG. FIG. 1B is a schematic top view of the light emitting device 10. FIG. FIG. 1A is a cross-sectional view along line VV of FIG. 1B. Also, FIG. 1C is an enlarged cross-sectional view showing an enlarged portion A surrounded by a dashed line in FIG. 1A. The configuration of the light emitting device 10 will be described with reference to FIGS. 1A to 1C.

The light-emitting device 10 includes a substrate 11, a light-emitting element 12 placed on the substrate 11, a light-transmitting member 13 placed on the light-emitting element 12, and a light-transmitting member 14 placed on the light-transmitting member 13. have Further, the light emitting device 10 is arranged on the substrate 11 so as to surround the light emitting element 12, the light transmitting member 13 and the light transmitting member 14 while being separated from each of the light emitting element 12, the light transmitting member 13 and the light transmitting member 14. It has a frame 15 with a

The light emitting element 12 has its bottom surface arranged on the top surface of the substrate 11 . The bottom surface of the translucent member 13 is arranged on the top surface of the light emitting element 12 . The bottom surface of the light transmitting member 14 is arranged on the top surface of the light transmitting member 13 . The bottom surface of the frame 15 is arranged on the top surface of the substrate 11 .

The light-emitting device 10 also has a cover 16 formed on the substrate 11 and covering the side surfaces of the light-emitting element 12 , the light-transmitting member 13 and the light-transmitting member 14 , and the upper surface of the frame 15 . Moreover, the cover 16 has an upper surface S1 exposed to the outside.

In this embodiment, the substrate 11 is a mounting substrate having wiring for power supply to the light emitting element 12 . The substrate 11 has a mounting surface for the light emitting element 12, and has first wiring and second wiring formed on the mounting surface and electrically insulated from each other. Further, the substrate 11 has a first external electrode and a second external electrode formed on a surface (rear surface) opposite to the mounting surface and electrically connected to the first wiring and the second wiring, respectively. It has electrodes. The light emitting element 12 is mounted on the substrate 11 and connected to wiring on the substrate 11 .

The light emitting element 12 is, for example, a semiconductor light emitting element such as a light emitting diode. In this embodiment, the light emitting element 12 has a semiconductor layer (not shown) made of a nitride semiconductor. The light emitting element 12 emits, for example, light in the blue region (420 to 470 nm wavelength) (hereinafter sometimes referred to as blue light).

In this embodiment, the light emitting element 12 includes a support substrate (for example, a silicon substrate), a semiconductor layer bonded to the first main surface of the support substrate, and a semiconductor layer formed on the first main surface of the support substrate. It has one electrode and a second electrode formed on a second main surface facing the first main surface of the supporting substrate and having a polarity different from that of the first electrode. The first electrode may be formed on a semiconductor layer joined to the first main surface of the support substrate.

A second electrode of the light emitting element 12 is electrically connected to a second wiring of the substrate 11 via a conductive joining member. A first electrode of the light emitting element 12 is electrically connected to a first wiring of the substrate 11 via a gold wire.

Note that the configuration of the light emitting element 12 on the substrate 11 is not limited to this. For example, the light emitting element 12 having another configuration includes a light emitting element having a growth substrate, a semiconductor layer grown on the growth substrate, and a first electrode and a second electrode formed on the semiconductor layer (hereinafter referred to as , referred to as a light emitting element 12A).

The light emitting element 12A can be bonded to the substrate 11 by, for example, bonding the surface of the growth substrate opposite to the semiconductor layer and the mounting surface of the substrate 11 with a bonding member. Also, the first electrode and the second electrode of the light emitting element 12 can be joined to the first wiring and the second wiring of the substrate 11 via gold wires, respectively. When the light emitting element 12A is placed on the substrate 11, a growth substrate is placed on the substrate 11, and a semiconductor layer is placed on the growth substrate.

Another configuration of the light emitting element 12 is a case where the semiconductor layer of the light emitting element 12A is bonded to the mounting surface of the substrate 11 (flip chip bonding, hereinafter referred to as the light emitting element 12B). In this case, the first wiring and the second electrode of the light emitting element 12B can be joined to the first wiring and the second wiring of the substrate 11 by a conductive joining member. When the light emitting element 12B is mounted on the substrate 11, the semiconductor layer is arranged on the substrate 11, and the growth substrate is arranged on the semiconductor layer.

In this embodiment, the light-emitting element 12 has a rectangular (square in this embodiment) top shape when viewed from a direction perpendicular to the mounting surface of the light-emitting element 12 on the substrate 11 . However, the top surface shape of the light emitting element 12 is not limited to a rectangular shape, and may be various shapes such as a circular shape, an elliptical shape, and a rectangular shape. In this embodiment, the top surface of the light emitting element 12 functions as the light extraction surface of the light emitting element 12 .

The translucent member 13 is a member that transmits light emitted from the light emitting element 12, and is made of a member that transmits at least visible light, for example. For example, the translucent member 13 can be made of epoxy resin, silicone resin, low-melting glass, or the like.

Further, the translucent member 13 may contain a wavelength converter, such as a phosphor, that converts the wavelength of light emitted from the light emitting element 12 . For example, as the phosphor, a green phosphor that converts blue light into green light, a yellow phosphor that converts blue light into yellow light, a red phosphor that converts blue light into red light, or the like can be used.

In addition, the structure of the translucent member 13 is not limited to this. For example, the translucent member 13 may be composed of a metal oxide nanoparticle sintered body that transmits the light emitted from the light emitting element 12 and the light converted by the phosphor. Also, the light-emitting device 10 may not have the translucent member 13 .

The light transmitting member 14 is arranged on the upper surface of the light transmitting member 13 . The light transmitting member 14 is a member that transmits the light emitted from the light emitting element 12 and/or the light converted by the wavelength converter, and is made of a member that transmits at least visible light, for example. For example, the light transmitting member 14 may be a glass plate, a sapphire plate, a YAG (yttrium aluminum garnet) plate, or the like.

Also, the light transmitting member 14 may contain a wavelength converter, such as a phosphor, that converts the wavelength of the light emitted from the light emitting element 12 . For example, as the phosphor, a green phosphor that converts blue light into green light, a yellow phosphor that converts blue light into yellow light, a red phosphor that converts blue light into red light, or the like can be used.

In addition, the structure of the light transmission member 14 is not limited to this. For example, the light transmission member 14 is made of acrylic resin, polycarbonate resin, epoxy resin, silicone resin, fluororesin, or metal oxide nano-particles, which transmits light emitted from the light emitting element 12 and light converted by the wavelength converter. It may be composed of a sintered body of particles.

The top surface of the light transmitting member 14 functions as a light extraction surface of the light emitting device 10 . In this embodiment, the top surface of the light transmitting member 14 has the same shape as the top surface of the light emitting element 12, for example, a rectangular shape. However, the top surface shape of the light transmitting member 14 is not limited to a rectangle, and may be a shape different from the top surface shape of the light emitting element 12 . Further, for example, the side surface of the light transmitting member 14 may be formed in a stepped shape, or may be inclined with respect to the upper surface.

The frame 15 is arranged on the substrate 11 so as to surround the light emitting element 12, the light transmitting member 13 and the light transmitting member 14 while being separated from each of the light emitting element 12, the light transmitting member 13 and the light transmitting member 14. there is Note that the frame 15 may be arranged so as to surround the outer periphery of the substrate 11 . Further, in this embodiment, the frame body 15 is formed integrally with the substrate 11 and together with the substrate 11 forms a lamp house having a recess for housing the light emitting element 12 . The frame 15 is made of, for example, an alumina compact.

The cover 16 is formed on the substrate 11 in a region outside the light emitting element 12 , the light transmitting member 13 and the light transmitting member 14 and surrounded by the frame 15 . Moreover, the cover 16 is formed so as to partially cover the upper surface of the frame 15 . Note that the cover 16 may cover a part of the upper surface of the frame 15 or may cover the entire frame 15 (the frame 15 may be embedded).

The cover 16 will be described in detail below. The cover 16 has an upper surface S1 exposed to the outside. Specifically, the cover 16 extends over the substrate 11 from the end of the upper surface of the light transmitting member 14 (that is, the light extraction surface) to the upper surface of the frame 15 (the surface opposite to the substrate 11). arranged consecutively. Moreover, the cover 16 is provided in an annular shape so as to surround the side surface of the light transmitting member 14 .

The cover 16 has an inner peripheral bottom surface in contact with the substrate 11, an inner peripheral side surface in contact with the side surface of the light transmitting member 14, an outer peripheral side surface in contact with the inner surface of the frame 15, and an outer peripheral bottom surface in contact with the upper surface of the frame 15. and an upper surface S1 provided on the opposite side of the inner peripheral bottom surface and the outer peripheral bottom surface and exposed to the outside.

In this embodiment, the case where the cover 16 is in contact with the entire side surface of the light transmitting member 14 will be described. However, the cover 16 may be in contact with only part of the side surface of the light transmitting member 14 . For example, the cover 16 extends from the end of the upper surface (light extraction surface) of the light transmitting member 14 toward the bottom surface of the light transmitting member 14 (the surface on which light from the light emitting element 12 and the light transmitting member 13 is incident), It is also possible to cover only the middle of the side surface of the light transmitting member 14 (that is, the area above the side surface of the light transmitting member 14).

Also, in this embodiment, the case where the cover 16 is in contact with the entire inner surface of the frame 15 will be described. However, the cover 16 may be in contact with only part of the inner surface of the frame 15 . For example, the cover 16 may cover only a partial region from the upper end to the lower end of the inner surface of the frame 15 (that is, the upper region of the inner surface of the frame 15).

Further, in this embodiment, the top surface of the frame 15 is configured to be higher than the top surface of the light transmitting member 14 from the substrate 11 . Therefore, the cover 16 is arranged at a higher position on the outer peripheral side surface than on the inner peripheral side surface. Moreover, in this embodiment, the covering 16 contains a thermosetting resin as described later. Therefore, the upper surface S1 of the cover 16 has a shape slightly recessed toward the substrate 11 due to heat shrinkage after curing. In addition, the upper surface of the frame 15 may be arranged so as to be flush with the upper surface of the light transmitting member 14 . Moreover, the upper surface of the frame 15 may be arranged at a position lower than the upper surface of the light transmitting member 14 so that the cover 16 can easily cover the upper surface of the frame 15 .

Next, the internal structure of the cover 16 will be described with reference to FIGS. 1C and 1D. First, as shown in FIG. 1C, the coating 16 includes a plurality of titanium oxide particles dispersed within the coating 16 (first, second and third titanium oxide particles P1, P2 and P3 are shown in FIG. 1C). shown).

In this embodiment, the coating 16 includes a medium (matrix) for dispersing the particle groups PT. Examples of the medium include thermosetting silicone resins and epoxy resins. That is, the covering 16 is made of a resin containing particles. In addition, in this embodiment, the resin body as the medium has a property of transmitting visible light.

In this embodiment, the cover 16 is a sealing material for sealing the light-emitting element 12 and other functional elements (such as a Zener diode that stabilizes the voltage applied to the light-emitting element 12) and wiring on the substrate 11. function as a body.

Further, as shown in FIG. 1D, each of the first to third titanium oxide particles P1 to P3 includes particle main bodies P10, P20 and P30, a coating film P11 covering the particle main bodies P10, P20 and P30, respectively, P21 and P31.

Specifically, in the present embodiment, the first titanium oxide particles P1 consist of a particle body P10 (a portion made of titanium oxide) and a coating film that covers the surface of the particle body P10 and protects the particle body P10. and P11. The coating film P11 is, for example, a film made of an organic substance such as alumina, silica, or polyol. Similarly, each of the second and third titanium oxide particles P2 and P3 has particle bodies P20 and P30 and coating films P21 and P31 that coat the surfaces of the particle bodies P20 and P30.

Next, as shown in FIG. 1D, in the particle group PT, each of the first and third titanium oxide particles P1 and P3 has more It has a portion NB with a small bandgap.

In addition, as shown in FIG. 1C, in this embodiment, the particle group PT is arranged such that the density of the small bandgap portion NB in each particle decreases from the upper surface S1 of the coating 16 toward the substrate 11. contains first to third titanium oxide particles P1 to P3 dispersed in For clarity of illustration, the first and third titanium oxide particles P1 and P3 are hatched in FIG. 1C. In this embodiment, each of the titanium oxide particles P1 to P3 is made of titanium dioxide (TiO ₂ ) having a rutile crystal structure.

The density of the small bandgap portion NB in each of the first to third titanium oxide particles P1 to P3 is, for example, the ratio of the small bandgap portion NB in each particle. , is the occupied area of the small bandgap portion NB on the surface of each of the grain bodies P10 to P30.

In the present embodiment, in the first titanium oxide particles P1 dispersed in the region closest to the upper surface S1 in the particle group PT, the bandgap is smaller than the other portions in the first titanium oxide particles P1. The portion NB has the highest density (having the portion NB with the small bandgap at the first density).

For example, the small bandgap portion NB of the first titanium oxide particles P1 has a bandgap energy smaller than the energy of visible light (specifically, the energy of the wavelength of visible light). For example, the small bandgap portion NB of the first titanium oxide particles P1 includes emitted light (blue light in this embodiment) from the light emitting element 12 and emitted light from the translucent member 13 (in this embodiment, blue light). It has a bandgap energy (eg, about 1.5 eV) smaller than that of blue light and yellow light).

Further, in the second titanium oxide particles P2 dispersed in the region closest to the substrate 11 in the particle group PT, the density of the portion NB having the smallest bandgap in the second titanium oxide particles P2 is the lowest ( with the smaller bandgap portion NB of the second density).

For example, the second titanium oxide particles P2 hardly have the small bandgap portion NB, as shown in FIG. 1D. Therefore, for example, the second titanium oxide particles P2 have bandgap energy higher than the energy of the light emitted from the light emitting element 12 in any portion (almost all).

For example, when the second titanium oxide particles P2 have a rutile crystal structure, the second titanium oxide particles P2 have a bandgap energy of 3.0 eV. When the second titanium oxide particles P2 have an anatase-type crystal structure, the second titanium oxide particles P2 have a bandgap energy of 3.2 eV.

Further, in the third titanium oxide particles P3 dispersed between the first and second titanium oxide particles P1 and P2 in the particle group PT, the portion of the third titanium oxide particles P3 where the bandgap is small NB (for example, a portion having a bandgap energy of 1.5 eV) is the density between the first titanium oxide particles P1 and the second titanium oxide particles P2 (the third density (the first density and the second densities between )) are provided.

It is understood that titanium oxide crystals have a smaller bandgap due to oxygen deficiency. More specifically, oxygen vacancies form an intermediate level between the valence band and conduction band of titanium oxide. The bandgap referred to here is the energy gap between this intermediate level and the valence band or conduction band. Therefore, for example, the small bandgap portion NB in the first or third titanium oxide particles P1 or P3 is understood to be a portion in which oxygen deficiency occurs in the crystal of titanium oxide.

Here, the bandgap (local bandgap in each particle) of the first to third titanium oxide particles P1 to P3 will be described. A crystal with a bandgap has the optical property of absorbing light of wavelengths with energies greater than its bandgap energy and transmitting light of wavelengths with energies less than this energy.

In this embodiment, the small bandgap portion NB of each of the first and third titanium oxide particles P1 and P3 has a bandgap energy smaller than the bandgap energy corresponding to the wavelength of visible light. Therefore, each of the first and third titanium oxide particles P1 and P3 absorbs visible light by the small bandgap portion NB. Therefore, in this example, the first and third titanium oxide particles P1 and P3 are black or gray under observation using white visible light because the visible light is absorbed.

In this embodiment, each of the second titanium oxide particles P2 does not (almost does not have) the small bandgap portion NB, and thus transmits and scatters visible light. Therefore, in this example, each of the second titanium oxide particles P2 presents a white color under observation using white visible light.

Further, in this embodiment, the regions in which the first, second and third titanium oxide particles P1, P2 and P3 in the coating 16 are dispersed are respectively referred to as the first, second and third dispersed regions ( or first, second and third particle layers) 16A, 16B and 16C, the first and third dispersion regions 16A and 16C are visible light absorption regions (hereinafter simply referred to as absorption regions function as AB. On the other hand, the second dispersion area 16B functions as a visible light scattering/reflection area (hereinafter simply referred to as a scattering/reflection area) SC that scatters and reflects visible light.

Also, the first and third titanium oxide particles P1 and P3 are dispersed only in a region near the upper surface S1 of the coating 16. As shown in FIG. For example, the first and third titanium oxide particles P1 and P3 are dispersed only in a region within a depth range of 20 μm or less from the top surface S1. Therefore, the covering 16 functions as an absorption region AB in the vicinity of the upper surface S1, and functions as a scattering reflection region SC inside thereof.

Further, in this embodiment, the first to third titanium oxide particles P1 to P3 are dispersed in the coating 16 (inside the medium) with a uniform dispersion density as a whole. However, the first to third titanium oxide particles P1 to P3 may be dispersed such that the dispersion density (content) gradually increases from the upper surface S1 of the coating 16 toward the substrate 11. FIG. For example, the dispersion density of the second titanium oxide particles P2 within the second dispersion region 16B may be higher than the dispersion density of the first titanium oxide particles P1 within the first dispersion region 16A.

The first, second and third titanium oxide particles P1, P2 and P3 have coating films P11, P21 and P31, respectively, so that the first to third titanium oxide particles P1 to P3 are yellowed by ultraviolet rays. Has resistance to discoloration (yellowing resistance) and weather resistance.

If resistance to yellowing due to ultraviolet rays and weather resistance are not required, the first to third titanium oxide particles P1 to P3 may not have the coating films P11 to P31. For example, when the absorption region AB is formed in the vicinity of the upper surface S1 of the cover 16, the absorption region AB can absorb ultraviolet rays. Therefore, in this case, each of the first to third titanium oxide particles P1 to P3 may not have the coating films P11 to P31.

2A, 2B, and 2C are diagrams showing each step of the method for manufacturing the light emitting device 10. FIG. Each of FIGS. 2A-2C is a cross-sectional view similar to FIG. 1A during each step. A method for manufacturing the light emitting device 10 will be described with reference to FIGS. 2A to 2C.

First, FIG. 2A is a diagram showing the substrate 11 on which the light-emitting element 12, the light-transmitting member 13, the light-transmitting member 14, the frame 15, and the particle-containing resin 16P are formed. In this embodiment, first, a lamp house is prepared in which a frame 15 is bonded to a substrate 11 (step 1). Next, the light emitting element 12 is placed on the substrate 11 and bonded (step 2). Next, a light-transmitting member 14 (glass plate) is adhered onto the light-emitting element 12 via a light-transmitting member 13 containing a yellow phosphor (step 3).

Subsequently, silicone containing titanium oxide particles P0 similar to the third titanium oxide particles P3 is applied as the particle-containing resin 16P on the region between the light transmitting member 14 and the frame 15 on the substrate 11 and on the upper surface of the frame 15. Fill with resin (step 4). Then, the particle-containing resin 16P is heated and cured (step 5). In this example, rutile-type titanium dioxide having an average particle size of 250 nm and a bandgap energy of 3.0 eV was used as the titanium oxide particles P0. A silicone resin was used as the resin medium of the particle-containing resin 16P. The concentration of the titanium oxide particles P0 in the particle-containing resin 16P was set to 16 wt%.

FIG. 2B is a diagram showing the upper surface of the particle-containing resin 16P while the upper surface S0 of the particle-containing resin 16P is being irradiated with laser light. After curing the particle-containing resin 16P, the upper surface S0 of the particle-containing resin 16P exposed to the outside in the light emitting element 12 and the frame 15 is irradiated with the laser beam LB (step 6).

In this example, a laser light source LS that emits laser light LB with a wavelength of 355 nm was prepared. Then, the upper surface S0 of the particle-containing resin 16P was irradiated with the laser beam LB having a beam diameter of φ45 μm and an output of 50 kW/cm ² while scanning at a speed of 1000 mm/sec. The energy of light with a wavelength of 355 nm is about 3.5 eV, and the bandgap energy of rutile-type titanium dioxide is 3.0 eV. Therefore, the energy of the laser beam LB is higher than the bandgap energy of the titanium oxide particles P0. Therefore, the laser beam LB is absorbed by the titanium oxide particles P0.

As a result, oxygen atoms are released from the titanium oxide particles P0 irradiated with the laser beam LB. Further, by adjusting the irradiation intensity, irradiation time, focal position, etc. of the laser beam LB, the laser beam LB is irradiated only to the titanium oxide particles P0 in the vicinity of the upper surface S0. Therefore, titanium oxide particles with the most oxygen deficiency are generated near the upper surface S0 in the particle-containing resin 16P, and the degree of deterioration (oxygen deficiency) of the titanium oxide particles P0 decreases as the distance from the upper surface S0 increases.

As a result, the titanium oxide particles P0 with many oxygen defects present in the vicinity of the upper surface S0 of the particle-containing resin 16P become the first titanium oxide particles P1 having a high density and a small bandgap portion NB. Further, the titanium oxide particles P0 separated from the upper surface S0 of the particle-containing resin 16P become the third titanium oxide particles P3 having relatively few small bandgap portions NB.

When separated from the upper surface S0 by a predetermined distance (the distance at which the laser beam LB is blocked by the titanium oxide particles), the titanium oxide particles P0 maintain their properties without being affected by the laser irradiation. Therefore, the titanium oxide particles P0 existing in the vicinity of the substrate 11 become the second titanium oxide particles P2 which hardly have the small bandgap portion NB. In this manner, a coating containing a plurality of titanium oxide particles (particle group PT) dispersed such that the density of the portion NB having a smaller bandgap than the other portions in each particle is gradually lowered by laser irradiation. 16 and a light emitting device 10 including the same can be fabricated (FIG. 2C).

In the step of irradiating the laser light LB (step 6), the laser light source LS and the laser light source LS are used so as not to alter other materials such as the medium of the cover 16 (for example, silicone resin), the light transmitting member 13 and the light transmitting member 14. It is preferable to adjust the laser light LB. For example, by irradiating the laser beam LB under the conditions described above, it is possible to alter only the titanium oxide particles P0 while suppressing alteration of other materials.

The inventors of the present application have found that the laser beam LB under the above conditions (and the output within the range of 25 to 75 kW/cm ² ) is generated by the silicone resin as the medium of the cover 16, the translucent member 13, and the fluorescence in the translucent member 13. It is confirmed that the body and the glass plate as the light transmitting member 14 are not degraded. In this embodiment, a silicone resin having a transmittance of 60% or more for light with a wavelength of 355 nm is used as the medium of the cover 16 .

Note that the method for manufacturing the light emitting device 10 is not limited to this. For example, after the particle-containing resin 16P is applied and allowed to stand still for a predetermined time, the particle-containing resin 16P is heated to cause the titanium oxide particles P0 to settle. As a result, it is possible to form the coating 16 in which the dispersion density of the titanium oxide particles P0 on the upper surface S1 side is lowered.

FIG. 3 is a diagram schematically showing light paths in the light emitting device 10. As shown in FIG. First, most of the light emitted from the light-emitting element 12 passes through the light-transmitting member 13 and the light-transmitting member 14 and exits from the upper surface (light extraction surface) of the light-transmitting member 14 like the light L1. taken out to the outside.

Next, light (such as light L2) entering the scattering reflection area SC of the cover 16 from the side surface of the light transmission member 14 is reflected by the scattering reflection area SC and returns to the light transmission member 14 . Then, light such as the light L2 is taken out from the upper surface of the light transmitting member 14 to the outside.

On the other hand, the light (light such as light L3) entering the absorption region AB of the cover 16 from the side surface of the light transmitting member 14 is absorbed by the absorption region AB. Also, light such as light L3 is sufficiently attenuated even if it is not completely absorbed in the absorption region AB. Therefore, almost no light is extracted from the upper surface S1 of the cover 16. FIG.

Moreover, even when the lights L1 and L2 are taken out from the light transmitting member 14, some of them may return to the light emitting device 10. FIG. Specifically, for example, when the light-emitting device 10 is used for lighting, the entire light-emitting device 10 is housed in the housing of the lighting device. Further, the light extracted from the light emitting device 10 is projected from the lighting device toward a region (space) to be illuminated via various optical systems such as lenses. Therefore, it is assumed that part of the light extracted from the light emitting device 10 is reflected or scattered by the housing and optical system and returns to the light emitting device 10 .

On the other hand, in the light emitting device 10 , the cover 16 is provided on the upper surface of the frame 15 and the cover 16 also has the absorption region AB on the upper surface of the frame 15 . Therefore, almost the entire surface of the substrate 11 except for the light extraction surface, which is the upper surface of the light transmitting member 14, becomes the absorption region AB. Therefore, even light returning toward the frame 15 from the outside of the light emitting device 10 is absorbed or sufficiently attenuated by the absorption region AB of the cover 16, as shown as light L4 in FIG.

In the region on the upper surface of the frame 15, it is sufficient to give priority to the absorption of external light, such as the light L4, incident on the light emitting device 10. FIG. That is, in the region on the upper surface of the frame 15, it is not necessary to consider absorption of light such as the light L3. Therefore, in the area on the upper surface of the frame 15, the cover 16 has a lower absorptance than the area on the substrate 11 (the area on the substrate 11 between the light transmitting member 14 and the frame 15). may be

Therefore, for example, among the titanium oxide particles dispersed in the area near the upper surface S1 in the cover 16, the titanium oxide particles dispersed in the area above the upper surface of the frame 15 are the light transmitting member 14 on the substrate 11. and a portion NB having a lower bandgap than the titanium oxide particles dispersed in the region between the frame members 15 .

More specifically, for example, the particle group PT does not have to have the first titanium oxide particles P1 (the first dispersed region 16A) in the region on the upper surface of the frame 15 . That is, only the second and third titanium oxide particles P2 and P3 are dispersed in the region above the frame 15 on the upper surface S1 of the cover 16, and the third titanium oxide particles P3 are arranged near the upper surface S1. may be Also, for example, only the third titanium oxide particles P3 (the third dispersed region 16C) may be provided in the region on the upper surface of the frame 15 .

For example, when the first titanium oxide particles P1 are not formed, in step 6 for forming the absorption region AB, the scanning speed of the laser light LB is increased or the beam of the laser light LB is increased in the region above the frame 15. Adjustments such as increasing the diameter may be performed. Further, by devising the conditions of step 6 in this manner, the processing time of the particle-containing resin 16P can be shortened.

As described above, when the light extraction surface of the light emitting device 10 is viewed, almost no light is extracted from regions other than the upper surface of the light transmitting member 14 by having the cover 16 . Therefore, since the light and darkness are clearly separated between the area of the light transmitting member 14 and the other areas, it is possible to obtain emitted light with high contrast. In other words, stray light can be reduced when the light-emitting device 10 is used as a lighting device.

In addition, the covering 16 has high reflectivity with respect to most of the light incident on the covering 16 from the light emitting element 12, the light transmitting member 13, and the light transmitting member 14 side. It absorbs light. Therefore, the light emitting device 10 can emit high-contrast light without sacrificing a decrease in light output.

Also, the absorption region AB of the cover 16 can be easily formed only by adding the step of irradiating the laser beam LB (step 6). Therefore, it is possible to easily provide the light emitting device 10 with high output and high contrast.

In this embodiment, the resin body, which is the dispersion medium for the particle groups PT, is integrally formed. That is, for example, each of the first to third titanium oxide particles P1 to P3 in the covering 16 is dispersed in the same medium. Further, there is no medium boundary between each of the first to third dispersion regions 16A to 16C. Therefore, even if the absorption region AB is provided, the mechanical strength of the covering 16 is maintained, and the optical function is stabilized as described above. Therefore, the covering 16 and the light emitting device 10 are of high quality and long life.

Further, in this embodiment, the particle groups PT have a uniform dispersion density as a whole within the coating 16 . Therefore, each of the first to third titanium oxide particles P1 to P3 is dispersed in the coating 16 with a density within a range comparable to each other. Therefore, even when the absorption region AB is provided, the thermal expansion coefficient of the covering 16 as a whole is made uniform, thereby maintaining the mechanical strength of the covering 16 . Therefore, the covering 16 and the light emitting device 10 are of high quality and long life.

In addition, as described above, the dispersion density of the titanium oxide particles in the coating 16 may gradually decrease toward the substrate 11 . For example, when the dispersion density of the second titanium oxide particles P2 on the density substrate 11 side is increased and the dispersion density of the first titanium oxide particles P1 on the upper surface S1 side is decreased, the resin on the upper surface S1 of the cover 16 Cracking can be suppressed.

More specifically, for example, using the particle-containing resin 16P in which the content of the titanium oxide particles P0 in step 4 is changed from 16 wt% to 32 wt%, a stationary step (a step of settling the titanium oxide particles P0) is performed. When the coating 16 is formed through . In this case, it is possible to improve the reflectance in the scattering reflection area SC while maintaining the absorptivity of the absorption area AB, and furthermore it is possible to prevent resin cracking.

Also, in this embodiment, the coating 16 has a thermosetting epoxy resin or silicone resin having a refractive index within the range of 1.4 to 1.55 as the resin medium. Further, the particle group PT includes, for example, anatase-type titanium oxide particles having a refractive index of approximately 2.5 or rutile-type titanium oxide particles having a refractive index of approximately 2.7. Considering the scattering of light within the coating 16, the particle group PT (especially the second titanium oxide particles P2) preferably has a higher refractive index than the resin medium.

Further, the particle size (average particle size) of each of the first to third titanium oxide particles P1 to P3 in the particle group PT of the coating 16 is in the range of 150 to 350 nm, considering that good diffuse reflection is obtained. preferably within Further, the average particle size of the first to third titanium oxide particles P1 to P3 is 1 to 1/1 to the wavelength of light (visible light) entering the coating 16 (for example, the wavelength in the medium of the silicone resin). By setting it within the range of about 4, Mie scattering with a high backscattering ratio can be generated, and extremely good diffuse reflection can be obtained. By adjusting the average particle size of the particles in the particle group PT in consideration of these factors, the reflectance in the scattering reflection area SC can be increased. Also in the absorption region AB, the light is scattered and absorbed by the particles with a high probability, so that the absorptivity can be increased.

Further, the concentration of the particle group PT in the coating 16 is preferably in the range of 5 to 70 wt% in consideration of obtaining the desired light reflectivity and light absorption, and ease of production (particle-containing resin Considering the ease of application of 16P) and manufacturing costs, it is more preferable to be in the range of 8 to 30 wt%. The configuration of the particle groups PT and the medium in the coating 16 is merely an example.

Further, as shown in FIG. 1D, each of the first to third titanium oxide particles P1 to P3 has a coating film P11 to P31 (that is, the titanium oxide particle P0 used for forming each particle is coated). film), in the irradiation step (step 6) of the laser beam LB during the manufacture of the light-emitting device 10, a high-power laser with a wavelength of 355 nm is used to effectively and stably produce each of the particle bodies P10 to P30. Oxygen vacancies can be generated on the surface of the In particular, when a coating film is provided for the purpose of imparting yellowing resistance (resistance to ultraviolet rays) to each particle, it is necessary to stably form the absorption region AB only in a thin region of several μm from the upper surface S1 of the coating 16. can be done.

Further, when the particle size of the titanium oxide particles P0 is substantially equal to the wavelength of the laser beam LB within the particle-containing resin 16P, in the region within the particle-containing resin 16P, the titanium oxide particles P0 have a large backscatter ratio. Scattering occurs. As a result, the laser beam LB is scattered and reflected in the vicinity of the upper surface S0 of the particle-containing resin 16P. can be done.

In addition, by using light having a wavelength with energy higher than the bandgap energy of the titanium oxide particles P0 in the particle-containing resin 16P as the laser light LB, the laser light LB can be absorbed by the titanium oxide particles P0. Therefore, the absorption region AB can be formed only in a thin region of several μm to 20 μm in the vicinity of the upper surface S1 of the cover 16. FIG.

4A is a cross-sectional view of a light emitting device 10A according to Modification 1 of Embodiment 1. FIG. The light-emitting device 10A has the same configuration as the light-emitting device 10 except for the configuration of the translucent member 13A. In this modified example, the translucent member 13A partially covers the side surface of the light emitting element 12 . That is, the translucent member 13A is formed on the upper surface and side surfaces of the light emitting element 12. As shown in FIG. In this modification, the cover 16 is in contact with the light emitting element 12 in the lower area of the side surface of the light emitting element 12, and covers the light emitting element 12 in the upper area via the translucent member 13A.

In the light emitting device 10A, the cover 16 has a portion above the side surface of the light emitting element 12 that does not come into contact with the side surface of the light emitting element 12 . When the cover 16 is configured in this manner, the light emitted from the side surface of the light emitting element 12 can be guided by the light transmitting member 13A and made incident on the outer edge portion of the light transmitting member 14 . Therefore, the amount of light extracted from the outer edge of the light transmitting member 14 can be increased. Therefore, the light emitting device 10A has a high contrast.

4B is a cross-sectional view of a light emitting device 10A according to Modification 2 of Embodiment 1. FIG. The light-emitting device 10B has the same configuration as the light-emitting devices 10 and 10A except for the configuration of the translucent member 13B. In this modified example, the translucent member 13B covers the entire side surface of the light emitting element 12 . That is, the translucent member 13B is in contact with the entire top surface and side surfaces of the light emitting element 12 . In this modification, the cover 16 covers the side surface of the light emitting element 12 via the translucent member 13B.

In the light emitting device 10B, the cover 16 does not come into contact with the side surface of the light emitting element 12 completely. When the cover 16 is configured in this manner, almost all of the light emitted from the side surface of the light emitting element 12 can enter the outer edge portion of the light transmitting member 14 by the light transmitting member 13B. Therefore, the amount of light extracted from the outer edge of the light transmitting member 14 can be increased. Therefore, the light emitting device 10B has a high contrast.

4C is a cross-sectional view of a light-emitting device 10C according to Modification 3 of Example 1. FIG. The light-emitting device 10C has the same configuration as the light-emitting device 10 except for the configuration of the light-transmitting member 13C and the light-transmitting member 14A. In this modified example, the light transmitting member 14A has an upper surface that is larger than the upper surface of the light emitting element 12. As shown in FIG. Further, the light transmitting member 13C is formed from the side surface of the light emitting element 12 to the bottom surface of the light transmitting member 14A.

In this modification, the light emitted from the light emitting element 12 is incident on the entire bottom surface of the light transmitting member 14A through the light transmitting member 13C, and then extracted to the outside from the top surface of the light transmitting member 14A. Moreover, the cover 16 covers the side surface of the light transmitting member 13C and the side surface of the light transmitting member 14A. Therefore, for example, the light emitted from the side surface of the light emitting element 12 can enter the outer edge portion of the light transmitting member 14A through the light transmitting member 13C. Therefore, for example, it is possible to increase the size of the light extraction surface without changing the size of the light emitting element 12, and to provide the light emitting device 10C in which the decrease in contrast is suppressed.

4D is a cross-sectional view of a light-emitting device 10D according to Modification 4 of Example 1. FIG. The light-emitting device 10D has the same configuration as the light-emitting device 10 except for the configuration of the light-transmitting member 13D and the light-transmitting member 14B. In this modified example, the light transmitting member 14B has an upper surface smaller than the upper surface of the light emitting element 12 . Also, the light transmitting member 13D is formed from the upper surface of the light emitting element 12 to the side surface of the light transmitting member 14B.

In this modified example, the light emitted from the light emitting element 12 is incident on the bottom and side surfaces of the light transmitting member 14B through the light transmitting member 13D, and then extracted to the outside from the top surface of the light transmitting member 14B. In addition, the cover 16 covers the side surfaces of the light emitting element 12 and the light transmitting member 13D, and the upper portion of the side surface of the light transmitting member 14B. Therefore, for example, it is possible to reduce the size of the light extraction surface without changing the size of the light emitting element 12, and to provide the light emitting device 10D with high output and high contrast.

4E is a cross-sectional view of a light-emitting device 10E according to Modification 5 of Example 1. FIG. The light-emitting device 10E has the same configuration as the light-emitting device 10 except that the light-transmitting member 13 and the light-transmitting member 14 are not provided. The light emitting device 10E has a substrate 11, a light emitting element 12 arranged on the substrate 11, and a cover 17 covering the side surface of the light emitting element 12. As shown in FIG. Further, in this modification, the light-emitting device 10E has a frame 15A having a height that matches the height (thickness) of the light-emitting element 12 . The cover 17 is provided on the area between the frame 15A and the light emitting element 12 on the substrate 11 and on the upper surface of the frame 15A.

The cover 17 has the same configuration as the cover 16 except that it covers the side surface of the light emitting element 12 . The cover 17 covers the side surface of the light emitting element 12 and the upper surface of the frame 15A, and has an upper surface S1 exposed to the outside. Further, similarly to the coating 16, the coating 17 has a plurality of layers dispersed in such a manner that the density of the portion NB having a smaller bandgap than the other portions in each particle is lower from the upper surface S1 toward the substrate 11. titanium oxide particles (for example, first to third titanium oxide particles P1 to P3).

In this modified example, the upper surface of the light emitting element 12 is exposed to the outside. In this case, the emitted light from the light emitting element 12 is directly taken out without passing through another medium. Also in the light-emitting device 10E, since the coating 17 contains the particle groups PT, the light-emitting device can achieve high output and high contrast.

In this embodiment, the case where the cover 16 has the absorption region AB and the scattering reflection region SC for visible light has been described. However, the configuration of the cover 16 is not limited to this. For example, the light emitting element 12 may have a configuration that emits light in a band other than visible light. In this case, the absorption region AB and the scattering reflection region SC of the coating 16 absorb and reflect light in the other wavelength band and/or light converted to another wavelength by the wavelength converter, respectively. It's fine if you have it.

In other words, for example, a region having light absorptivity and light reflectivity corresponding to the wavelengths of emitted light from the light emitting element 12 and emitted light from the wavelength converter included in the light transmitting member 13 or the light transmitting member 14. The particles in the coating 16 and their bandgap configuration, as well as the medium, need only be adjusted so as to have a

Further, in this case, considering that the absorption region AB and the scattering reflection region SC are effectively provided in the coating 16, for example, the titanium oxide particles in the particle group PT are the light emitted from the light emitting element 12 and/or the transmission light. It is preferable that the particles have an average particle diameter corresponding to the wavelength in the coating 16 of the emitted light from the wavelength converter included in the optical member 13 or the light transmitting member 14 .

Further, in consideration of maintaining mechanical strength, the coating 16 preferably has an integrally formed resin medium (for example, silicone resin) in which the plurality of titanium oxide particles of the particle group PT are dispersed. .

Further, in this embodiment, the case where the particle group PT includes the first to third titanium oxide particles P1 to P3 has been described, but the configuration of the particle group PT is not limited to this. For example, the particle group PT may be composed of only two types of titanium oxide particles P1 and P2.

In this case, for example, the coating 16 is arranged at a position closest to the upper surface S1, and has a plurality of first regions (portions NB) having a high density of portions (portions NB) having a bandgap smaller than the energy of the light emitted from the light emitting element 12. and a plurality of portions (portions NB) arranged closer to the substrate 11 than the first titanium oxide particles P1 and having a bandgap smaller than the energy of the light emitted from the light emitting element 12 (portions NB) at a low density. and the second titanium oxide particles P2.

Further, for example, the particle group PT may contain at least the first titanium oxide particles P1. That is, the particle group PT is a plurality of titanium oxide particles (first titanium oxide particles P1) dispersed in the vicinity of the upper surface S1 of the coating 16 and having a portion NB having a bandgap smaller than that of other portions in each particle. should have

In addition, the particles forming the absorption regions AB and the scattering reflection regions SC in the particle group PT are not limited to titanium oxide particles. For example, zinc oxide (ZnO) has properties similar to titanium oxide. For example, zinc oxide has a bandgap energy of 3.37 eV and is transparent to visible light. In addition, zinc oxide has a property of absorbing ultraviolet rays (for example, laser light LB) having a wavelength of 355 nm. Furthermore, the refractive index of zinc oxide is 2.0, which is greater than the refractive index of silicone resin (1.4 to 1.55). Zinc oxide has the property of absorbing visible light by forming a deep donor level due to oxygen deficiency to reduce the bandgap (a portion corresponding to the small bandgap portion NB is formed).

Therefore, for the particle group PT, it is possible to use metal oxide crystals, such as titanium oxide particles and zinc oxide particles, which have the property of transmitting visible light in a crystal state with no oxygen deficiency and absorbing visible light due to oxygen deficiency. can. For example, metal oxide particles having such properties may be substituted for the first to third titanium oxide particles P1 to P3, or in addition to the first to third titanium oxide particles P1 to P3. It may be contained in the particle group PT.

In addition to the titanium oxide particles or the zinc oxide particles, the particle group PT scatters emitted light from the light emitting element 12 and/or emitted light from the wavelength converter included in the light transmitting member 13 or the light transmitting member 14. particles may be added. The particles include metal carbides such as silicon carbide (SiC), silicon nitride (Si2N3), gallium nitride (GaN), aluminum nitride (AlN), aluminum oxide (Al2O3), metal oxides, metal nitrides and the like. particles.

In other words, the particle group PT only needs to have a plurality of particles dispersed within the coating 16 . When the particle group PT contains a plurality of particles including particles other than titanium oxide particles and zinc oxide particles, the plurality of particles are dispersed in the coating 16 at a uniform density, or the particles are dispersed in the coating 16 at a uniform density. It suffices if the particles are dispersed so that the density gradually increases toward Further, for example, all the particles included in the particle group PT may be dispersed at the concentration described above.

Moreover, in this embodiment, the case where the light emitting device 10 has one light emitting element 12 has been described. However, the light emitting device 10 may have multiple light emitting elements 12 . Also in this case, for example, the covering 16 having the particle groups PT may cover the side surface of the light transmitting member 14 and the upper surface of the frame 15 .

Thus, for example, the light-emitting device 10 includes a substrate 11, a light-emitting element 12 arranged on the substrate 11, a light-transmitting member 14 arranged on the light-emitting element 12, and the light-transmitting member 14 on the substrate 11. It has a frame 15 arranged so as to surround it, and a cover 16 covering the side surface of the light transmitting member 14 and the top surface of the frame 15 on the substrate 11 and having an upper surface S1 exposed to the outside.

Further, the coating 16 has a particle group PT composed of a plurality of particles dispersed within the coating 16 . Further, the particles of the particle group PT are dispersed in the vicinity of the upper surface S1 of the coating 16, and a plurality of titanium oxide particles (first titanium oxide particles P1) or with zinc oxide particles. Therefore, it is possible to provide the light emitting device 10 with a simple configuration and high output and high contrast.

Further, for example, the light-emitting device 10E includes a substrate 11, a light-emitting element 12 arranged on the substrate 11, a frame 15A arranged on the substrate 11 so as to surround the light-emitting element 12, and a light-emitting element 15A arranged on the substrate 11. and a cover 17 covering the 12 side surfaces and the upper surface of the frame 15A and having an upper surface S1 exposed to the outside.

Moreover, the coating 17 has a particle group PT composed of a plurality of particles dispersed within the coating 17 . Further, the particles of the particle group PT are dispersed in the vicinity of the upper surface S1 of the coating 17, and a plurality of titanium oxide particles (first titanium oxide particles P1) or with zinc oxide particles. Therefore, it is possible to provide the light emitting device 10E with a simple configuration and high output and high contrast.

FIG. 5A is a cross-sectional view of a light emitting device 20 according to Example 2. FIG. 5B is a top view of the light emitting device 20. FIG. FIG. 5A is a cross-sectional view along line WW in FIG. 5B. Also, FIG. 5C is an enlarged cross-sectional view showing an enlarged portion B surrounded by a dashed line in FIG. 5A.

The light-emitting device 20 has the same configuration as the light-emitting device 10 except for the configuration of the covering 21 . In the light-emitting device 20, the cover 21 covers the side surface of the light transmitting member 14 and has an upper surface S1 exposed to the outside, like the cover 16 does.

In this embodiment, the coating 21 is composed of a plurality of titanium oxide particles dispersed from a partial region of the upper surface S1 toward the substrate 11 so that the density of the small bandgap portion NB within each particle is low. It has a particle group PT1 containing (first to third titanium oxide particles P1, P2 and P3). In FIG. 5C, the titanium oxide particles P1 and P3 are hatched.

In other words, of the particle group PT1, the first titanium oxide particles P1 forming the absorption region AB are dispersed in a portion of the upper surface S1 of the covering 21. As shown in FIG. That is, the covering 21 has the first dispersed region 21A only on part of the upper surface S1. Moreover, the coating 21 has a second dispersed region 21B in which only the second titanium oxide particles P2 are uniformly dispersed toward the substrate 11 in another region of the upper surface S1. The covering 21 can be formed, for example, by irradiating only a part of the upper surface S0 of the particle-containing resin 16P with the laser beam LB.

In this embodiment, the first titanium oxide particles P1 are dispersed in the coating 21 so as to surround the light transmitting member 14 at a predetermined distance (distance D) from the side surface of the light transmitting member 14. . Therefore, the covering 21 partially reflects and scatters the light (like the light L3 in FIG. 3) entering the covering 21 from the side surface of the light transmitting member 14 . The light-emitting device 20 has a suitable configuration, for example, when higher output is prioritized between higher contrast and higher output.

The balance between the output of the extracted light and the contrast depends on the distance D (FIG. 5C) from the side surface of the light transmitting member 14 to the absorption area AB in the cover 21, that is, the scattering reflection area SC in contact with the side surface of the light transmitting member 14. can be adjusted by adjusting the thickness up to the absorption region AB.

FIG. 6 is a diagram showing the distribution of light output from the light emitting device 20. As shown in FIG. The horizontal axis of FIG. 6 indicates the position of the light-emitting device 20 along the WW line of FIG. 5B, and the vertical axis indicates the light output (luminance normalized by the maximum value).

In FIG. 6, a light-emitting device having a coating in which only the second titanium oxide particles P2 are dispersed is prepared as the light-emitting device 100 according to the comparative example, and the output from the light-emitting device 100 is are superimposed on the measurement results of the light emitting device 20 and indicated by a dashed line.

In addition, for the measurement, each of the light-emitting devices 20 and 100 is housed, and a light-shielding light-shielding glass having an opening having substantially the same shape and size as the upper surface of the substrate 11 is provided in the region above the light-transmitting member 14 in the light-emitting devices 20 and 100 . A housing (test housing) was prepared. Then, the light output from the light emitting devices 20 and 100 at the opening of the housing was measured, and the results shown in FIG. 6 were obtained.

Specifically, it is assumed that the light-emitting device is mounted in a light-shielding housing that accommodates the light-emitting device. In this case, a part of the housing is provided with a light extraction opening in which an optical system such as a lens is arranged, and the light emitted from the light emitting device is extracted to the outside of the housing through the light extraction opening. Become.

The opening of the test housing is a virtual light extraction port of the housing in which the light emitting device 20 is supposed to be actually accommodated. That is, the graph of FIG. 6, which is the measurement result of the light output at the opening of the test housing, can be said to be the evaluation result of the light emitting device 20 in an environment close to the actual use environment.

As shown in FIG. 6, in the light-emitting device 20, compared to the light-emitting device 100, the output from the region other than the light-emitting element 12 (light-transmitting member 14) is greatly suppressed, and the light output from the region of the light-emitting element 12 is high. is emitted. Also, the maximum output values of the light emitting devices 20 and 100 were substantially the same. That is, it can be seen that the light-emitting device 20 is a high-contrast light-emitting device without lowering the output.

Here, the absorption area AB on the frame 15 in the cover 21 (the same applies to the cover 16 in Example 1) will be described. As shown in FIG. 6, it can be seen that the light near the frame 15 measured in the light emitting device 100 is greatly suppressed in the light emitting device 20 . This is because the cover 21 covers the upper surface of the frame 15 and the cover 21 also has the absorption area AB on the upper surface of the frame 15 .

Specifically, as shown in FIG. 6, in the region near the frame 15 in the light-emitting device 100, although it is away from the light-extracting surface, the light-transmitting member 14 (and the scattering reflection region SC), A small amount of light is measured. This is the result of measuring light such as the light L4 shown in FIG. 3 (for example, stray light that repeats reflection within the test housing and travels toward the upper surface of the frame 15).

On the other hand, in the light emitting device 20 , the light output monotonically and sharply decreases as the distance from the light transmitting member 14 increases, and almost no light is measured in the vicinity of the frame 15 . This is because the stray light traveling toward the frame 15 in the test case is absorbed by the absorption region AB in the cover 21 near the frame 15 . Therefore, the light-emitting device 20 (and the light-emitting device 10) having the cover 21 (and the cover 16) can maintain high contrast even when operating in an environment in which it is actually used.

Next, in consideration of maintaining a high contrast, as shown in FIG. Preferably, a reflective area SC is provided. This is because light with an intensity of less than 1/100 is light with an intensity that does not deteriorate the contrast. In this example, the upper limit of this distance D was about 0.2 mm.

It should be noted that this distance D corresponds to the distance that light can enter in the cover 21 (scattering reflection area SC). Also, the distance D varies depending on the dispersion density of the titanium oxide particles. Therefore, for example, as described above, the output from the light transmitting member 14 and the surrounding covering 21 is measured, and the side surface of the light transmitting member 14 is located at a position where the output is 1/100 of the upper surface of the light transmitting member 14. It is preferable to provide the scattering reflection area SC up to a position close to .

That is, the distance D is the distance from the side surface of the light transmitting member 14 to the position within the region of the upper surface S1 of the cover 21 where light having 1/100 or more of the maximum intensity of the light emitted from the light transmitting member 14 is emitted. is preferably In addition, the cover 21 is provided in a region outside the position where light having an intensity of 1/100 of the light output from the light transmitting member 14 is emitted (a position separated by a distance D from the side surface of the light transmitting member 14). It is preferable to have a plurality of titanium oxide particles (eg, first to third titanium oxide particles P1, P2 and P3) dispersed so that the density of the small bandgap portion NB within the particles is low.

Also in this embodiment, the light-emitting device 20 may not have the light-transmitting member 13 and the light-transmitting member 14 . Moreover, the cover 21 does not have to have the scattering reflection area SC over the entire periphery near the side surface of the light emitting element 12 . For example, the coating 21 is composed of a plurality of titanium oxide layers (first to second layers) dispersed in layers so that the density of the small bandgap portion NB in each particle is lowered from a portion of the upper surface S1 toward the substrate 11. 3) of titanium oxide particles P1, P2 and P3).

Thus, in this embodiment, for example, the first titanium oxide particles P1 of the coating 21 (a portion located closest to the upper surface S1 and having a bandgap smaller than the energy of the light emitted from the light emitting element 12 (Titanium oxide particles having the portion NB) at a higher density than other particles) are dispersed in the coating 21 so as to surround the side surface of the light transmitting member 14 at a predetermined distance D from the side surface of the light transmitting member 14. It is Therefore, the light emitting device 20 with high output and high contrast can be provided.

In addition, the coating 21 has a portion (part NB) at a density lower than that of the first titanium oxide particles P1. Therefore, the light emitting device 20 can emit high-contrast light and has a high output.

FIG. 7A is a cross-sectional view of a light emitting device 30 according to Example 3. FIG. 7B is a top view of the light emitting device 30. FIG. FIG. 7A is a cross-sectional view along line XX of FIG. 7B. The light-emitting device 30 has the same configuration as the light-emitting device 10 except for the configuration of the covering 31 .

Cover 31 has a plurality of recesses 31R on upper surface S1. In this embodiment, as shown in FIG. 7B, each recess 31R of the cover 31 is formed in a groove shape so as to surround the light emitting element 12, the light transmitting member 13, and the light transmitting member . Moreover, each of the recessed portions 31R has a columnar (scale-like) inner wall.

The coating 31 can be formed, for example, by irradiating the upper surface S0 of the particle-containing resin 16P with laser light LB (ultraviolet region wavelength light) in a superimposed manner (multiple times). Specifically, a laser beam LB having a wavelength of 355 nm and an output of 25 kW/cm ² or more is irradiated in a specific pattern, and this is irradiated again in the same pattern, thereby sequentially sublimating and removing the silicone resin from the surface. An irradiation mark of the laser beam LB remains on the surface. As a result, grooves corresponding to the beam diameter of the laser beam LB and its moving direction are formed on the upper surface S0 of the particle-containing resin 16P. This laser mark becomes the concave portion 31R of the cover 31. As shown in FIG.

The concave portion 31R of the cover 31 can be formed not only by irradiating the laser beam LB multiple times, but also by adjusting the output of the laser beam LB, the scanning speed, and the like. Also, the shape of the recess 31R is not limited to the illustrated shape. For example, the upper surface of the cover 31 may be formed with a convex portion, or may be formed with continuous wave-like unevenness. The cover 31 may have an upper surface S1 having various unevenness.

In this embodiment, similarly to the coating 16, the coating 31 includes titanium oxide particles (the first and third It has a particle group PT comprising titanium oxide particles P1 and P3).

In the present embodiment, the upper surface S1 of the cover 31 has, for example, repeated recesses 31R, so that the surface area exposed to the outside is larger than that of a flat surface (for example, the upper surface S1 of the cover 16). increase. This increases the surface area of the absorbent area AB provided in the covering 31 . Therefore, the cover 31 highly efficiently absorbs light (like the light L3 in FIG. 3) entering the cover 31 from the side surface of the light transmitting member 14 . Therefore, the light-emitting device 30 has a suitable configuration, for example, when priority is given to contrast over contrast and output.

In this embodiment, the case where the recess 31R is formed on the entire upper surface S1 of the cover 31 has been described. However, the recessed portion 31R may be formed only in part of the upper surface S1 of the cover 31 . Also, the shape of the recess 31R is not limited to that shown in FIGS. 7A and 7B. The cover 31 should just have the recessed part 31R on the upper surface S1.

10, 10A, 10B, 10C, 10C, 10D, 10E, 20, 30 Light-emitting device 11 Substrate 12 Light-emitting element 13 Light-transmitting member 14 Light-transmitting member 15, 15A Frames 16, 17, 21, 31 Covers P1, P2, P3 titanium oxide particles PT, PT1 particle group

Claims (17)

a substrate;
a light emitting element disposed on the substrate;
a light transmitting member disposed on the light emitting element;
a frame disposed on the substrate so as to surround the light transmitting member;
a cover disposed on the substrate, covering the side surface of the light transmitting member and the upper surface of the frame, and having an upper surface exposed to the outside;
The coating has a particle group consisting of a plurality of particles dispersed in the coating,
The particles of the particle group are dispersed only in the vicinity of the upper surface of the coating and include a plurality of titanium oxide particles or zinc oxide particles each having a portion with a smaller bandgap than other portions within each particle. A light emitting device. Among the plurality of titanium oxide particles or zinc oxide particles, the plurality of titanium oxide particles or zinc oxide particles dispersed in the region on the upper surface of the frame are the light-transmitting member on the substrate and the frame. 2. The method according to claim 1, wherein each particle has a portion having a lower bandgap than the other portion and having a density lower than that of the plurality of titanium oxide particles or zinc oxide particles dispersed in the region between the particles. luminous device. 3. The light-emitting device according to claim 1, wherein the plurality of particles in the particle group are dispersed at a uniform density within the coating. 3. The light-emitting device according to claim 1, wherein said plurality of particles in said particle group are dispersed in said coating such that the density thereof gradually increases from said upper surface toward said substrate. In the plurality of titanium oxide particles or zinc oxide particles in the particle group, a portion having a smaller bandgap than the other portion in each particle has a lower density from the upper surface of the coating toward the substrate. 5. The light emitting device according to any one of claims 1 to 4, characterized in that: 6. The light emitting device according to any one of claims 1 to 5, wherein the cover has a resin medium in which the plurality of particles are dispersed and integrally formed. The particle group includes a plurality of first titanium oxide particles or zinc oxide particles that are provided closest to the upper surface and have a portion with a smaller bandgap than the other portions at the highest density, and the plurality of first titanium oxide particles or zinc oxide particles. A plurality of first titanium oxide particles or zinc oxide particles provided closer to the substrate than the plurality of first titanium oxide particles or zinc oxide particles and having a portion having a lower density than the plurality of first titanium oxide particles or zinc oxide particles and a bandgap smaller than the other portions . 7. The light emitting device according to any one of claims 1 to 6, comprising 2 titanium oxide particles or zinc oxide particles. The light-emitting device according to any one of claims 1 to 7, wherein the plurality of particles in the particle group are dispersed within a range of 5 to 70 wt% in the coating. 9. The light emitting device according to any one of claims 1 to 8, wherein the plurality of titanium oxide particles or zinc oxide particles have a particle body and a coating film that coats the particle body. 8. The light emitting device according to claim 7, wherein the plurality of first titanium oxide particles or zinc oxide particles are dispersed in a region within a depth range of 20 μm or less from the top surface of the covering. . The plurality of titanium oxide particles or zinc oxide particles are dispersed in the coating so as to surround the side surface of the light-transmitting member at a predetermined distance from the side surface of the light-transmitting member. The light emitting device according to any one of claims 1 to 10. The predetermined distance is from the side surface of the light transmitting member to a position within the region of the upper surface of the cover where light having a maximum intensity of 1/100 or more of the maximum intensity of light emitted from the light transmitting member is emitted. 12. The light-emitting device of claim 11, wherein the light-emitting device is a distance. The light emitting device according to any one of claims 1 to 12, wherein the cover has a plurality of unevenness on the upper surface. 14. The plurality of titanium oxide particles or zinc oxide particles according to any one of claims 1 to 13, wherein the particles have an average particle size corresponding to the wavelength of light emitted from the light emitting element within the coating. luminous device. a substrate;
a light emitting element disposed on the substrate;
a frame arranged on the substrate so as to surround the light emitting element;
a cover disposed on the substrate, covering the side surface of the light emitting element and the upper surface of the frame, and having an upper surface exposed to the outside;
The coating has a particle group consisting of a plurality of particles dispersed in the coating,
The particles of the particle group are dispersed only in the vicinity of the upper surface of the coating and contain a plurality of titanium oxide particles or zinc oxide particles each having a smaller bandgap portion than other portions. A light emitting device. In the plurality of titanium oxide particles or zinc oxide particles in the particle group, a portion having a smaller bandgap than the other portion in each particle has a lower density from the upper surface of the coating toward the substrate. 16. The light-emitting device according to claim 15, characterized by: 17. The light emitting device according to claim 15, wherein the cover has a resin medium in which the plurality of particles are dispersed and integrally formed.

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