TWI521171B - Light-emitting device - Google Patents

Description

Illuminating device

The present invention relates to a light-emitting device, and more particularly to a light-emitting device having a plurality of light-transmissive layers.

The conventional light-emitting device is limited by the limitation of the opaque metal substrate, and the light emitted by the light-emitting element cannot emit light from the metal substrate, thereby limiting the uniformity of the light distribution of the light-emitting device. Therefore, how to improve the uniformity of the light distribution of the light-emitting device is one of the efforts of the industry.

The invention relates to a light-emitting device which can improve the uniformity of light distribution.

According to an embodiment of the invention, a lighting device is proposed. The light emitting device comprises a light transmissive substrate and a light emitting element. The light transmissive substrate comprises a first light transmissive layer having a refractive index N ₁ , a second light transmissive layer having a refractive index N ₂ , and a third light transmissive layer having a refractive index N ₃ , and a third The light transmissive layer includes a recess that exposes the surface of the second light transmissive layer. The light-emitting element is disposed in the concave portion. The light-emitting element has a bottom light-emitting surface facing the exposed second light-transmitting layer, and the light-emitting element has a refractive index of N _chip . Wherein, the refractive index of air is defined as N _air , and N _chip >N ₂ >N ₁ , N ₃ >N _air . In order to better understand the above and other aspects of the present invention, the preferred embodiments are described below, and in conjunction with the drawings, the detailed description is as follows:

100‧‧‧Lighting device

110‧‧‧Transparent substrate

111‧‧‧First light transmission layer

112‧‧‧Second light transmission layer

112s‧‧‧ side

112u‧‧‧ surface

113‧‧‧The third light transmission layer

113u, 120u‧‧‧ upper surface

113r‧‧‧ recess

113w‧‧‧ side wall

114‧‧‧First electrode line

115‧‧‧Second electrode line

120‧‧‧Lighting elements

121‧‧‧First electrical contact

122‧‧‧Second electrical contacts

120b‧‧‧Glossy

120s‧‧‧Stained side

130‧‧‧wavelength conversion layer

A1‧‧‧ first angle

A2‧‧‧second angle

D1, D2, D3‧‧‧ optical loss

L1, L2, L3, L4‧‧‧ rays

N ₁ , N ₂ , N ₃ , N _chip , N _air ‧‧ ‧ refractive index

ΔN1, △N2, △N3‧‧‧ refractive index difference

1 is a cross-sectional view of a light emitting device in accordance with an embodiment of the present invention.

Fig. 2 is a view showing the appearance of Fig. 1.

1 is a cross-sectional view of a light emitting device in accordance with an embodiment of the present invention. The light emitting device 100 includes a light transmissive substrate 110, a light emitting element 120, and a wavelength conversion layer 130.

The overall thickness of the light transmissive substrate 110 is between 0.1 mm and 5 mm. The transparent substrate 110 includes a first light transmissive layer 111, a second light transmissive layer 112, and a third light transmissive layer 113 that are sequentially stacked. The refractive index of the first light transmissive layer 111 is N ₁ , the refractive index of the second light transmissive layer 112 is N _{2 ,} and the refractive index of the third light transmissive layer 113 is N ₃ . The refractive index of the light-emitting element 120 is N _chip , and the refractive index of air is defined as N _air . The relationship of the above refractive indices is N _chip > N ₂ > N ₁ and N ₃ > N _air . In one embodiment, the materials of the first light transmissive layer 111, the second light transmissive layer 112, and the third light transmissive layer 113 may be selected from the group consisting of sapphire, metal oxide, tantalum carbide, single crystal germanium, polycrystalline germanium, glass, Plastic, in which metal oxides such as zinc oxide, titanium oxide, and plastics such as polycarbonate (Polycarbonate, PC), polymethylmethacrylate (PMMA), methyl methacrylate (MS) or Polystyrene (PS). As long as the first light-transmitting layer 111, the second light-transmitting layer 112, and the third light-transmitting layer 113 can satisfy the above refractive index relationship, the first light-transmissive layer 111, the second light-transmitting layer 112, and the third portion are not limited in the embodiment of the present invention. The material of the light transmissive layer 113. In addition, the transmittances of the first light transmissive layer 111, the second light transmissive layer 112, and the third light transmissive layer 113 are greater than 70%, but the embodiment of the invention is not limited thereto.

Embodiment, the refractive index of the light emitting element is approximately 2.5 N _chip 120, a first light-transmitting layer 111 of a refractive index N ₁ to about 1.8, the refractive index of the light-transmitting layer 113 of the third N ₃ may be a first light-transmitting layer 111 of the embodiment The refractive index N ₁ is substantially the same, and the refractive index N _{2 of the} second light transmissive layer 112 is about 2.1. In this design, the material of the first light transmissive layer 111 may be glass, and the material of the second light transmissive layer 112 may be selected from metal oxides such as zinc oxide and titanium oxide, and the material of the third light transmissive layer 113 may be A light transmissive layer 111 is similar.

The third light transmissive layer 113 includes a recess 113r that exposes the surface 112u of the second light transmissive layer 112. The light emitting element 120 is provided in the recess 113r. The depth of the recess 113r is between about 0.05 mm and 0.5 mm; however, the depth of the recess 113r may depend on the thickness of the light-emitting element 120, which is not limited in the embodiment of the present invention. The upper surface 120u of the light-emitting element 120 can be aligned with the upper surface 113u of the third light-transmissive layer 113 by the thickness of the light-emitting element 120 and the depth of the recess 113r. In another embodiment, the upper surface 120u of the light emitting element 120 may be higher or lower than the upper surface 113u of the third light transmissive layer 113.

The light-emitting element 120 has a bottom light-emitting surface 120b facing the second light-transmitting layer 112 exposed from the concave portion 113r, so that the light L1 emitted from the bottom light-emitting surface 120b sequentially passes through the second light-transmitting layer 112 and the first light-transmitting layer 111. And the light. Due to the design of N _chip > N ₂ &gt _; N ₁ , the change in refractive index from the light-emitting element 120 to the first light-transmitting layer 111 is made gentle, and this reduces the light loss of the light ray L1.

The greater the refractive index change at the interface through which the light ray L1 passes, the greater the light loss. For example, if the second light transmissive layer 112 is omitted, the refractive index difference ΔN1=N _chip −N _{1 at} the interface between the light emitting element 120 and the first light transmissive layer 111, and the light L1 passes through the interface of the refractive index difference ΔN1. The loss is assumed to be D1. In this embodiment, the refractive index difference ΔN2=N _chip -N _{2 at} the interface between the light-emitting element 120 and the second light-transmitting layer 112, and the refractive index difference between the second light-transmitting layer 112 and the first light-transmitting layer 111 N3=N ₂ -N ₃ , wherein ΔN2 and ΔN3 are both smaller than ΔN1. The light loss at the interface of the light ray L1 passing through the refractive index difference ΔN2 is assumed to be D2, and the light loss at the interface passing through the refractive index difference ΔN3 is assumed to be D3. In terms of optical loss, since the refractive index change between the light-emitting element 120 to the first light-transmitting layer 111 of the present embodiment is slowed down (ΔN2→ΔN3), the sum of the optical losses D2 and D3 is still smaller than the optical loss D1. . That is to say, due to the design of the second light transmissive layer 112 of the present embodiment, the refractive index change between the light emitting element 120 and the first light transmissive layer 111 is prevented from being excessively changed, so that the light loss of the light L1 can be reduced.

The light emitting element 120 is, for example, a light emitting diode wafer. In this embodiment, the light-emitting element 120 is a flip-chip light-emitting diode wafer. In detail, the light-emitting element 120 includes a first electrical contact 121 and a second electrical contact 122. The first electrical contact 121 and the second electrical contact 122 are formed on the bottom light-emitting surface 120b of the light-emitting element 120. on. The transparent substrate 110 further includes a first electrode line 114 and a second electrode line 115. The first electrical contact 121 and the second electrical contact 122 are respectively connected to the first electrode line 114 and the second electrode line 115. The first electrode line 114 and the second electrode line 115 are electrically connected.

The light emitting element 120 further includes a side light emitting surface 120s facing the side wall 113w of the third light transmitting layer 113 of the recess 113r. After the light L2 emitted from the side light emitting surface 120s penetrates the third light transmitting layer 113 and enters the second light transmitting layer 112, since N ₂ >N ₁ and N ₂ >N ₃ , and the second light transmitting layer 112 is sandwiched Between the first light transmissive layer 111 and the third light transmissive layer 113, the probability of total reflection of the light L2 in the second light transmissive layer 112 is large. Since the light ray L2 is totally reflected in the second light transmitting layer 112, the light loss of the light ray L2 from the side surface 112s of the second light transmitting layer 112 can be reduced.

In this embodiment, the side light emitting surface 120s and the side wall 113w of the third light transmitting layer 113 of the concave portion 113r are parallel to each other. The angle between the bottom light emitting surface 120b of the light emitting element 120 and the side light emitting surface 120s is the first angle A1, and the first angle A1 is an obtuse angle. The second angle A2 between the second light transmissive layer 112 and the third light transmissive layer 113 in the recess 113r is complementary to an acute angle of the first angle A1, wherein the second angle A2 is between 30 degrees and 90 degrees. In another embodiment, the relationship between the first angle A1 and the second angle A2 is not limited to being complementary. For example, the first angle A1 may be 90 degrees, and the second angle A2 may be between 30 degrees and 90 degrees. The light ray L2 emitted from the side light-emitting surface 120s can penetrate the third light-transmitting layer 113 and enter the second light-transmitting layer 112. The embodiment of the present invention does not limit the relationship between the first angle A1 and the second angle A2. The defined side light exit surface 120s and the side wall 113w must be parallel.

The wavelength conversion layer 130 is disposed above the light emitting element 120. The wavelength conversion layer 130 includes a phosphor that can be excited by the light-emitting element 120 to emit a longer wavelength of light, and the light L3 emitted from the upper surface 120u of the light-emitting element 120 is converted by the wavelength conversion layer 130 to be different. The color light is out.

In addition, as shown in FIG. 1 , since the side light emitting surface 120s of the light emitting element 120 is adjacent to the third light transmitting layer 113, the light L4 emitted from the side light emitting surface 120s of the light emitting element 120 can pass through the third through before being emitted to the air. In the light layer 113, the light loss is reduced. Further, the refractive index of the wavelength conversion layer 130 is lower than that of the third light transmissive layer 113 and the local refractive indices of the wavelength conversion layers 130 are inconsistent; therefore, if the third light transmissive layer 113 is omitted, the light is emitted from the side of the light emitting element 120. The light L4 emitted from the surface 120s enters the wavelength conversion layer 130 and then exits to the air, which increases the light loss. In contrast, in the present embodiment, the refractive index change of the light-emitting element 120→the third light-transmissive layer 113→air is more moderate due to the design of the third light-transmitting layer 113 (compared to the light-emitting element 120→wavelength conversion layer 130→air) ), thus reducing the light loss. In one embodiment, the wavelength conversion layer 130 may not be formed in a space between the side light emitting surface 120s and the third light transmitting layer 113, or may fill at least a space between the side light emitting surface 120s and the third light transmitting layer 113. portion. In addition, the side light emitting surface 120s may be spaced apart from the third light transmitting layer 113 by a distance, or may directly contact the third light transmitting layer 113.

In summary, since the upper surface, the lower surface, and the side surface of the light-emitting device 100 of the embodiment of the present invention can emit light, the light-emitting device 100 becomes a full-circumferential light-emitting type light-emitting device, thereby improving the light-type distribution uniformity of the light-emitting device 100. .

Fig. 2 is a view showing the appearance of Fig. 1 (in order to avoid the complexity of the drawing, the light-emitting element and the wavelength conversion layer are not shown). The first electrode line 114 and the second electrode line 115 of the transparent substrate 110 extend along the surface 112u of the second light transmissive layer 112 and the sidewall 113w of the third light transmissive layer 113 to the upper surface 113u of the third light transmissive layer 113, respectively. The light emitting element 120 can transmit the first electrode line 114 and the second electrode line 115 extending from the upper surface 113u. The external circuit board (not shown) is electrically connected to the external circuit board to control the light emitting element 120 to emit light through the first electrode line 114 and the second electrode line 115. In another embodiment, the first electrode line 114 and the second electrode line 115 of the embodiment of the present invention may not be entirely exposed on the upper surface 113u. For example, a portion of the first electrode line 114 and/or a portion of the second electrode line 115 may extend within the interlayer of the first/second light transmissive layer or within the interlayer of the second/third light transmissive layer, and the first electrode The other portion of the line 114 and/or the other portion of the second electrode line 115 exposes the pad attached to the external power source to the upper surface 113u.

In conclusion, the present invention has been disclosed in the above preferred embodiments, and is not intended to limit the present invention. A person skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

100‧‧‧Lighting device

110‧‧‧Transparent substrate

111‧‧‧First light transmission layer

112‧‧‧Second light transmission layer

112s‧‧‧ side

112u‧‧‧ surface

113‧‧‧The third light transmission layer

113u, 120u‧‧‧ upper surface

113r‧‧‧ recess

113w‧‧‧ side wall

114‧‧‧First electrode line

115‧‧‧Second electrode line

120‧‧‧Lighting elements

121‧‧‧First electrical contact

122‧‧‧Second electrical contacts

120b‧‧‧Glossy

120s‧‧‧Stained side

130‧‧‧wavelength conversion layer

A1‧‧‧ first angle

A2‧‧‧second angle

L1, L2, L3, L4‧‧‧ rays

Claims (10)

A light-emitting device comprising: a light-transmissive substrate comprising: sequentially stacking a first light-transmitting layer having a refractive index N ₁ , a second light-transmitting layer having a refractive index of N ₂ , and a first refractive index of N ₃ a third light transmissive layer, and the third light transmissive layer includes a concave portion exposing the surface of the second light transmissive layer; a light emitting element is disposed in the concave portion, the light emitting element has a bottom light emitting surface facing the bare The second light transmissive layer, and the refractive index of the light emitting element is N _chip ; wherein the refractive index of air is defined as N _air , and N _chip > N ₂ > N ₁ , N ₃ > N _air . The illuminating device of claim 1, wherein the illuminating element further comprises a side light emitting surface facing the side wall of the third light transmitting layer of the recess. The illuminating device of claim 2, wherein the side light emitting surface and the side wall of the third light transmitting layer of the concave portion are parallel to each other. The light-emitting device of claim 3, wherein an angle between the bottom light-emitting surface of the light-emitting element and the side light-emitting surface is a first angle, and the first angle is an obtuse angle, and the first portion of the concave portion The angle between the two light transmissive layers and the third light transmissive layer is complementary to an acute angle of the first angle. The light-emitting device of claim 1, wherein the refractive index N ₁ is equal to the refractive index N ₃ . The illuminating device of claim 5, further comprising a wavelength conversion layer disposed above the illuminating element. The illuminating device of claim 6, wherein the wavelength conversion layer comprises a fluorescing element that is excited by the illuminating element to emit another wavelength of longer light. Light powder. The illuminating device of claim 1, wherein the material of the first light transmissive layer and the third light transmissive layer is glass, and the second light transmissive layer is a metal oxide. The illuminating device of claim 1, wherein the illuminating element is a light emitting diode chip. The illuminating device of claim 9, wherein the illuminating diode chip is a flip-chip diode chip.