White light LED device with large wide angle and module

Abstract

The utility model relates to a large wide angle white light LED device and module, comprising a substrate, an LED chip, a fluorescent glue layer and a transparent glue layer, the top of the LED chip is covered with a semi-transparent reflection layer, and the LED chip is fixed on the substrate; the fluorescent glue layer wraps the LED chip; and the transparent adhesive layer covers the surfaces of the fluorescent adhesive layer and the substrate. The large-wide-angle white light LED device and the large-wide-angle white light LED module have a large light emitting angle and a uniform light emitting effect.

Description

Technical Field

[0001] The utility model relates to the technical field of semiconductors, in particular to a wide-angle white light LED device and a module. Background Art

[0002] LED devices are considered as the next generation mainstream display technology because of their small light source size, ultra-high contrast, wide color gamut, greatly improved color vividness, reduced optical light mixing distance, and reduced screen thickness. They are used in display screens of electronic products such as computers and mobile phones, car display screens, indoor and outdoor billboards, stage backgrounds, and other fields. However, the traditional white light LED device generally has a light emission angle of only 120°, and the light emitted is brightest in the vertical center normal direction. As the light gradually deviates from the center normal direction, the light emission angle increases, and its brightness decreases accordingly, which limits its application in some fields. Therefore, how to increase the light emission angle of white light LED devices has become a problem that more and more engineers are concerned about.

[0003] At present, the commonly used method of secondary lens packaging is to increase the light output angle, such as Figure 1 The structure of an existing white light LED device for increasing the light output angle includes: a substrate 1, a light emitting chip 2, a fluorescent glue layer 3 and a transparent glue 4. The light emitting chip 2 is arranged at the center of the substrate 1; the fluorescent glue layer 3 wraps the light emitting chip 2 and is hemispherical, and the fluorescent glue layer is formed by mixing fluorescent powder into materials such as silica gel or silicone resin. Among them, the fluorescent powder converts the blue light emitted by the light emitting chip 2 into white light, and the mountain-shaped silica gel or silicone resin can act as a lens to expand the light output angle of the light emitting chip 2; the transparent glue 4 covers the surface of the fluorescent glue layer 3, which can further expand the light output angle of the light emitting chip 2.

[0004] However, the white light LED device in the prior art has high brightness at the center and low brightness around it, and there is a large difference in brightness between the top light and the side light, that is, there is a problem of uneven brightness in all directions. Utility Model Content

[0005] Based on this, the purpose of the utility model is to provide a wide-angle white light LED device and module, including a substrate, an LED chip, a fluorescent glue layer and a transparent glue layer, the top of the LED chip is covered with a semi-transmissive reflective layer and fixed on the substrate; the fluorescent glue layer wraps the LED chip; the transparent glue layer covers the surface of the fluorescent glue layer and the substrate.

[0006] Furthermore, the bottom of the LED chip is also covered with a semi-transmissive reflective layer.

[0007] Furthermore, a reflective platform with a reflective surface on the upper surface is included, the reflective platform is arranged around the outer side of the LED chip, and its height increases along the peripheral direction. The reflective platform can reduce the brightness difference between the center and the surrounding of the light source, thereby achieving a uniform light output effect.

[0008] Furthermore, the angle between the reflection surface of the reflection platform and the substrate is 10-30°.

[0009] Furthermore, the angle between the reflection surface of the reflection platform and the substrate is 15°.

[0010] Furthermore, the volume ratio between the LED chip and the fluorescent glue layer is 1:1.5-2.1.

[0011] Furthermore, the thickness of the fluorescent glue of the fluorescent glue layer is 0.32 mm.

[0012] Furthermore, it also includes a transparent bracket, which is arranged on the substrate and forms a cup-shaped structure with an upper opening with the substrate, and can transmit the light emitted by the LED chip. The transparent bracket plays a supporting role for the transparent adhesive layer.

[0013] Furthermore, the LED chip is fixed on the substrate by transparent insulating glue.

[0014] Furthermore, a large luminous angle LED module is provided, comprising a plurality of the aforementioned large wide-angle white light LED devices.

[0015] In order to better understand and implement the present invention, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of an LED device with increased light output angle in the prior art;

[0017] Figure 2 This is a schematic diagram of the LED chip of the wide-angle white light LED device of the utility model;

[0018] Figure 3 This is a schematic diagram of a wide-angle white light LED device of the utility model;

[0019] Figure 4 This is a light source path diagram of the wide-angle white light LED device of the utility model.

[0020] Reference numerals: substrate 1, light emitting chip 2, fluorescent adhesive layer 3 and transparent adhesive 4;

[0021] The substrate 10 , the transparent support 20 , the LED chip 30 , the underlay 32 , the electron-type semiconductor layer 34 , the active layer 35 , the hole semiconductor layer 36 , the electrode layer 37 , the semi-transparent reflective layer 38 , the reflection platform 40 , the fluorescent adhesive layer 50 , and the transparent adhesive layer 60 . DETAILED DESCRIPTION

[0022] See also Figure 2 , which is a schematic diagram of a wide-angle white light LED device according to Embodiment 1 of the present invention. The wide-angle white light LED device of the present invention comprises a substrate 10, a transparent bracket 20, an LED chip 30, a reflection platform 40, a fluorescent adhesive layer 50 and a transparent adhesive layer 60.

[0023] The substrate 10 is made of ceramic, and has a solder pad on its surface.

[0024] The transparent support 20 is an annular enclosure structure, fixed on the surface of the substrate 10, and forms a cup-shaped structure with an upper opening with the substrate 10. The transparent support 20 is light-transmissive, and the material is selected from PCT transparent material (polycyclohexylene dimethylene terephthalate resin), preferably one of EMC material (epoxy molding compound) or SMC transparent material (sheet molding compound).

[0025] The LED chip 30 is located in the cup-shaped structure of the transparent support 20, fixed at the center of the substrate 10, and electrically connected to the substrate 10 through the pad. Figure 3 The LED chip 30 includes a substrate 32, an electron-type semiconductor layer 34, an active layer 35, a hole semiconductor layer 36 and an electrode layer 37 which are stacked in sequence. The electron-type semiconductor layer 34 covers the surface of the substrate 32, the active layer 35 is located on one side of the surface of the electron-type semiconductor layer 34, so that the upper surface of the electron-type semiconductor layer 34 is partially exposed, and the hole semiconductor layer 36 covers the active layer 35. The electrode layer 37 is respectively arranged on the surface of the electron-type semiconductor layer 34 and the hole semiconductor layer 36.

[0026] When the current flows from the hole semiconductor layer to the electron semiconductor layer 34, the electrons of the electron semiconductor layer 34 and the holes of the hole semiconductor layer 36 diffuse to the active layer 35, and the electrons and holes recombine in the active layer 35, and generate energy in the form of photons. The photons formed can be emitted in all directions around, among which most of the photons are emitted in the vertical direction, forming light rays emitting in the vertical direction; a part of the photons are emitted through one or more structures in the hole semiconductor layer 36, the active layer 35, the electron semiconductor layer 34 and the substrate 32, and these photons deviate from the vertical direction under the action of refraction. The more structures they pass through, the more the photons deviate from the vertical direction; and a small part of the photons will be emitted from the horizontal direction of the side. Therefore, the brightness of the light emitted from the center of the LED chip in the vertical direction (center normal direction) is higher, and the brightness of the light radiated from the center to the surroundings that deviates from the center normal direction and forms a certain angle with the center normal direction is lower, and as the angle of deviation increases, the brightness of the emitted light is also lower.

[0027] Since the LED chip 30 is fixed on the substrate 10, the light radiated vertically downward and diagonally downward by the LED chip 30 cannot be used, resulting in light loss. The experimental new type first covers a semi-transparent reflective layer 38 on the bottom of the LED chip 30 to reflect the light emitted vertically downward and diagonally downward to the top and sides of the LED chip 30, thereby improving the light utilization efficiency.

[0028] Specifically, a DBR layer (distributed Bragg reflector) is provided at the bottom of the substrate 32 as a semi-transparent reflective layer. The DBR layer can realize the reflection or transmission of light of a specific wavelength, and is a multilayer film structure formed by alternating stacking of two materials with different refractive indices according to the periodicity of ABAB. The light undergoes multiple reflections and refractions in the multilayer film structure to form light rays emitted toward the top and sides of the LED chip 30. The material of the DBR layer can be selected from two of silicon oxide, titanium oxide, magnesium fluoride, yttrium oxide, zinc sulfide, zirconium oxide and silicon nitride.

[0029] Furthermore, a semi-transparent reflective layer 38 is covered on the exposed surface of the hole semiconductor layer 36. The semi-transparent reflective layer is a DBR layer (distributed Bragg reflector). A part of the light emitted by the LED chip to the top is emitted through the semi-transparent reflective layer, and the other part is reflected to the bottom DBR layer under the reflection effect of the semi-transparent reflective layer. The light is reflected multiple times between the top DBR layer and the bottom DBR layer to form light emitted from the center normal direction, which reduces the brightness of the light in the center normal direction, increases the brightness of the light emitted from the side of the LED chip, and reduces the brightness difference between the light emitted by the LED chip at different angles.

[0030] The LED chip 30 is a blue light LED chip, which is located in the cup-shaped structure formed by the transparent bracket 20 and the substrate 10. The LED chip 30 is fixed to the center of the substrate 10 by insulating glue and is electrically connected to the pad. In actual production, the insulating glue inevitably overflows from the bottom of the chip to the side, blocking the light from the side. Therefore, the utility model selects transparent insulating glue and uses its transparent characteristics to reduce the blocking of the light from the side of the chip by the glue overflowing from the bottom.

[0031] The reflecting platform 40 includes a supporting platform and a reflecting layer covering the surface of the supporting platform, and the reflecting layer forms a reflecting surface on the upper surface of the reflecting platform 40. The material of the supporting platform can be selected from plastics such as EMC (epoxy resin molding compound) and PCT (polycyclohexylene dimethylene terephthalate resin). The surface of the reflecting platform 40 is covered with a reflecting layer with a reflectivity greater than 90%, and the reflecting layer reflects light. Specifically, a DBR layer or a reflecting particle layer prepared by reflecting particles can be selected. The material of the reflecting particles includes one or more of graphite, graphene, titanium dioxide, zinc oxide, zinc sulfide, zinc barium white, and silver powder. The reflecting platform 40 is arranged in the transparent bracket 20, surrounded by the outer side of the LED chip 30, and its height increases along the peripheral direction. When the light emitted from the side of the LED chip 30 is emitted to the reflecting surface on the upper surface of the reflecting platform 40, the light is deflected, so that the brightness difference between the light emitted by the LED chip at different angles is reduced, and the light is emitted more uniformly.

[0032] The following describes the principle of the reflector 40 making the LED device emit light more uniformly:

[0033] The brightness of LED devices is generally expressed in terms of luminous intensity. Effective light emission refers to the maximum luminous intensity that can be achieved on the center line (center normal) of the LED device. When the luminous intensity of the light emitted by the LED device can reach 50% of the maximum luminous intensity, it is considered effective light emission, otherwise it is invalid light emission. The maximum angle formed between effective lights is the light emission angle of the LED device.

[0034] The setting of the above-mentioned DBR layer increases the luminous intensity on the side of the LED chip, but in the direction where the side of the LED chip deviates from the center normal at a larger angle (75-90°), there is still ineffective light with weaker luminous intensity; in the direction where the side of the LED chip deviates from the center normal at a medium angle (50-75°), although the luminous intensity of the light reaches the standard of effective light emission, there is still a difference from the maximum luminous intensity on the center normal.

[0035] The reflecting platform 40 concentrates and utilizes the ineffective light emitted from the side, and the light is superimposed to form effective light with higher luminous intensity. Specifically, the ineffective light on the side of the LED chip 30 is refracted in the direction of the medium angle deviating from the center normal, and the invalid light is superimposed with the light originally emitted in the direction of the medium angle deviating from the center normal. The brightness of the light emitted in the direction of the medium angle deviating from the center normal reduces the brightness difference between the center and the periphery of the LED device. Furthermore, in order to concentrate the ineffective light on the effective light whose original luminous intensity has a large difference with the maximum luminous intensity, so as to reduce the difference in luminous intensity of the effective light between various angles of the LED chip, the angle between the reflective surface on the upper surface of the reflecting platform 40 and the substrate 10 is set to 10 to 30°. Preferably, the angle between the reflective surface on the upper surface of the reflecting platform 40 and the substrate 10 is set to 15°. Please refer to Figure 4 , which is a light source path diagram of a wide-angle white light LED device. When the reflection platform 40 and the substrate 10 are at an angle of 15°, the light emitted from the side of the LED chip 30 in the horizontal direction of the substrate 10 (the direction deviating from the center normal by 90°) is reflected by the reflection surface on the upper surface of the reflection platform 40, and then the light is emitted from the direction at an angle of 30° to the substrate 10 (the direction deviating from the center normal by 60°), so that the brightness of the light in the direction deviating from the center normal by 60° is enhanced, and the difference in brightness of the light in the direction vertical to the center normal is reduced, thereby achieving a uniform light output effect.

[0036] The fluorescent glue layer 50 is located in the truncated cone structure of the reflector 40 on the surface of the substrate 10, wrapping the LED chip 30, and is hemispherical, and the bottom of the fluorescent glue layer 50 is in contact with the bottom of the reflector 40. The hemispherical fluorescent glue layer 50 is equivalent to a lens, so that the light emitted by the LED chip 30 is refracted through the fluorescent glue layer 50, and the light is refracted and emitted in a direction deviating from the center normal, which can further reduce the difference in light output brightness in the center normal direction of the LED chip and in the direction deviating from the center normal.

[0037] The composition of the fluorescent glue layer 50 includes silicone resin and fluorescent powder, which is formed by doping the fluorescent powder material in the silicone resin. The fluorescent powder material includes one or more materials that can be stimulated to emit light, such as YAG (yttrium aluminum garnet), KSF (potassium fluorosilicate), β-sialon (silicon aluminum oxynitride), nitride, QD (quantum dot) fluorescent powder, etc. The fluorescent powder material in the fluorescent glue layer 50 is excited by the light emitted by the LED chip 30, emits yellow light or other colors of light, and is mixed with the blue light emitted by the LED chip 30 to form white light, which plays a color conversion role.

[0038] Generally, the fluorescent glue layer 50 is prepared by the glue dispensing process, but the fluorescent glue layer 50 prepared by the glue dispensing process has certain instability, which may cause the LED device to leak blue light or emit light in a scattered manner. The technicians found that the amount of the fluorescent glue layer 50 is an important influencing factor: when the amount of the fluorescent glue layer 50 is small, it may not cover the LED chip 30, resulting in blue light leakage; when the amount of the fluorescent glue layer 50 is large, under the action of surface tension, the curvature formed on the surface of the fluorescent glue layer 50 is large, so that the thickness of the fluorescent glue layer 50 facing the top of the LED chip 30 is too large; when the amount of the fluorescent glue layer 50 is increased, gravity plays a dominant role, and the curvature formed on the surface of the fluorescent glue layer 50 is reduced, but the fluorescent glue layer 50 is easy to extend upward from the bottom along the side wall of the reflective platform 40, so that the thickness of the fluorescent glue layer 50 facing the side of the LED chip 30 is too large, so a suitable amount of fluorescent glue is required to make the thickness of the fluorescent glue layer 50 uniform. Furthermore, in order to more quickly and accurately determine the amount of fluorescent glue, the amount of fluorescent glue layer is determined based on the size of the chip, and the volume ratio between the LED chip 30 and the fluorescent glue layer 50 is set to 1:1.5-2.1. For example, when the size of the LED chip 30 is 10mil*30mil, the amount of the fluorescent glue layer 50 is set to 0.00015mL, and the center thickness of the fluorescent glue layer 50 is 0.32mm.

[0039] The transparent adhesive layer 60 is made of silicone resin material, covering the surface of the fluorescent adhesive layer 50 and the reflector 40, and filling the internal space of the cup-shaped structure formed by the transparent bracket 20 and the substrate 10. The top protrudes to form a hemispherical structure with uniform thickness, which further refracts the light emitted by the LED chip 30, reducing the difference in light output brightness in the normal direction of the center of the LED chip and the direction deviating from the normal direction of the center. The edge of the transparent adhesive layer 60 contacts the cup mouth surface of the cup-shaped structure of the transparent bracket 20, and the transparent bracket 20 supports the transparent adhesive layer 60. The thickness of the transparent adhesive layer 60 is made more uniform, and the degree of refraction of light emitted at different angles by the transparent adhesive layer is more consistent, thereby emitting more uniform light. Further, in order to prevent the transparent adhesive layer 60 from overflowing along the cup mouth of the transparent bracket 20, the adhesive amount of the transparent adhesive layer 60 is set to 0.006mL and the thickness is set to 0.69mm.

[0040] The working principle of the wide-angle white light LED device described in the utility model is introduced below:

[0041] The LED chip 30 emits light from the center to all directions. When the light is emitted to the DBR layer at the top and bottom of the LED chip 30, part of the light is refracted to the side of the LED chip 30, thereby reducing the brightness of the light emitted from the top of the LED chip 30. Furthermore, a fluorescent glue layer 50 with uniform thickness is provided according to the size of the chip, so that the light emitted by the LED chip 30 through the fluorescent glue layer 50 is white light, and the emitted light is relatively uniform. Furthermore, the light emitted through the fluorescent glue layer 50 is reflected to the reflection surface on the upper surface of the reflection platform 40, and the reflection platform 40 uses the invalid light emitted from the side to enhance the luminous intensity of the effective light on the side: the light emitted from the side of the fluorescent glue in the direction of a larger angle (75-90°) deviating from the center normal is reflected by the reflection surface on the upper surface of the reflection platform 40 to the direction of a medium angle (50-75°) deviating from the center normal on the side, forming an effective light with a higher light intensity, so that the light emission within the effective light angle range is uniform. The transparent adhesive layer 60 is supported by the transparent bracket 20 to form a transparent adhesive layer 60 with a relatively uniform thickness. When the light emitted by the fluorescent adhesive layer 50 or reflected by the reflector 40 passes through the transparent adhesive layer 60 with a uniform thickness, the light emitted at different angles is refracted by the transparent adhesive layer to a relatively consistent degree, thereby emitting relatively uniform light. By reducing the luminous intensity of the top of the LED chip, a series of settings to enhance the luminous intensity of the side, and ensuring that the thickness of the medium through which the light at each angle passes is uniform, a white light with a large light output angle and uniform light output is finally formed.

[0042] Correspondingly, the utility model also provides a display module, which includes a plurality of the above-mentioned wide-angle white light LED devices.

[0043] Compared with the prior art, the wide-angle white light LED device of the utility model reduces the light intensity emitted in the vertical direction of the center of the LED chip by setting a DBR layer on the LED chip, while increasing the light intensity emitted to the side. Furthermore, the invalid light on the side is superimposed on the effective light with weaker light intensity through the reflector structure, so that the LED device maintains a larger light output angle while achieving a uniform light output effect. A suitable volume ratio between the chip and the fluorescent glue is also set to further ensure the uniform light output effect of the wide-angle white light LED device.

[0044] The above-mentioned embodiments only express several implementation methods of the utility model, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the utility model patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the utility model, and the utility model is also intended to include these modifications and modifications.

Claims

1. A wide-angle white light LED device, characterized in that: It includes a substrate, an LED chip, a fluorescent glue layer and a transparent glue layer. The top of the LED chip is covered with a semi-transmissive reflective layer and fixed on the substrate; the fluorescent glue layer wraps the LED chip; and the transparent glue layer covers the surface of the fluorescent glue layer and the substrate.

2. A wide-angle white light LED device according to claim 1, characterized in that: The bottom of the LED chip is also covered with a semi-transmissive reflective layer.

3. A wide-angle white light LED device according to claim 2, characterized in that: It also includes a reflection platform with a reflection surface on its upper surface. The reflection platform is arranged around the outer side of the LED chip, and its height increases along the peripheral direction.

4. The wide-angle white light LED device according to claim 3, characterized in that: The angle between the reflection surface of the reflection platform and the substrate is 10-30 degrees.

5. The wide-angle white light LED device according to claim 4, characterized in that: The angle between the reflection surface of the reflection platform and the substrate is 15°.

6. The wide-angle white light LED device according to claim 5, characterized in that: The volume ratio between the LED chip and the fluorescent glue layer is 1:1.5-2.

1.

7. The wide-angle white light LED device according to claim 6, characterized in that: The thickness of the fluorescent glue of the fluorescent glue layer is 0.32 mm.

8. The wide-angle white light LED device according to claim 7, characterized in that: It also includes a transparent bracket, which is arranged on the substrate and forms a cup-shaped structure with an opening on the top with the substrate.

9. The wide-angle white light LED device according to claim 8, characterized in that: The LED chip is fixed on the substrate by transparent insulating glue.

10. A wide-angle white light LED module, characterized in that: The invention comprises a plurality of wide-angle white light LED devices as claimed in any one of claims 1 to 9.

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