Light emitting device

Abstract

The embodiment of the utility model provides a light-emitting device. The light emitting device includes: a light emitting chip; the first fluorescent glue layer surrounds the light-emitting chip; the second fluorescent glue layer is arranged on the first fluorescent glue layer and covers the light-emitting chip; wherein the horizontal height of the first fluorescent glue layer in the die bonding area does not exceed 125% of the thickness of the light-emitting chip, and the die bonding area is a longitudinal space corresponding to the light-emitting chip. The light-emitting device provided by the embodiment of the utility model can realize pure red light with high brightness and high color purity.

Description

Technical Field

[0001] The utility model relates to the technical field of lighting, in particular to a light-emitting device. Background Art

[0002] With the rapid development of the LED (light-emitting diode) packaging industry in recent years, the packaging process for white LEDs has matured. However, the pursuit of high color purity and high brightness for specialized colors still leaves significant room for improvement. For example, to achieve pure red light, in addition to using red light chips, a short-wavelength chip is generally considered to excite red powder. However, to ensure red light purity (e.g., greater than 96%), a long-wavelength red powder (e.g., one with an emission wavelength greater than 650 nanometers) must be used. The higher the red light purity requirement, the greater the wavelength and amount of red powder required. This results in a decrease in the luminous efficiency and brightness of the entire light-emitting unit, failing to meet green lighting requirements. Utility Model Content

[0003] Therefore, in order to overcome at least some of the defects and deficiencies in the prior art, an embodiment of the present invention provides a light emitting device.

[0004] The light-emitting device provided in an embodiment of the present invention includes: a light-emitting chip; a first fluorescent adhesive layer surrounding the light-emitting chip; and a second fluorescent adhesive layer disposed on the first fluorescent adhesive layer and covering the light-emitting chip. The height of the first fluorescent adhesive layer in the crystal-bonding region does not exceed 125% of the thickness of the light-emitting chip. The crystal-bonding region is defined as the longitudinal space corresponding to the light-emitting chip. By stimulating specific first and second fluorescent adhesive layers through the light-emitting chip, the red light emitted by the light-emitting device has a high brightness and a color purity exceeding 99%. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0006] Figure 1 A schematic structural diagram of a light emitting device provided in an embodiment of the present utility model.

[0007] Figure 2 This is another structural schematic diagram of the light-emitting device provided in an embodiment of the present utility model.

[0008] Figure 3 This is a spectrum diagram of the light-emitting device provided in an embodiment of the present utility model. DETAILED DESCRIPTION

[0009] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments described in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0010] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, top, bottom, horizontal, and vertical) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0011] In the embodiments of the present invention, references to "first," "second," and the like are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include at least one of the features.

[0012] See also Figure 1 and Figure 2 The light emitting device 10 provided by the embodiment of the present invention is a red light emitting device, which may include: a light emitting chip 100, a first fluorescent adhesive layer 200 and a second fluorescent adhesive layer 300.

[0013] The light-emitting chip 100 can be, for example, a violet light chip, a blue light chip, or a green light chip. This invention uses a blue light chip, which has been tested to have better excitation efficiency for most red phosphors, as an example. The wavelength band of the light-emitting chip 100 can be, for example, 450-460 nanometers. The first fluorescent adhesive layer 200 can, for example, surround the light-emitting chip 100, specifically, surrounding the sidewalls of the light-emitting chip 100. The second fluorescent adhesive layer 300 is disposed on the first fluorescent adhesive layer 200 and covers the light-emitting chip 100. Specifically, the first fluorescent adhesive layer 200 is located on the bottom layer, and the second fluorescent adhesive layer 300 is located on the top layer.

[0014] At least one of the first fluorescent glue layer 200 and the second fluorescent glue layer 300 has a first emission wavelength within the range of 630±2 nanometers, and at least one of the first fluorescent glue layer 200 and the second fluorescent glue layer 300 has a second emission wavelength within the range of 650-690 nanometers. This allows the emission spectrum of the light-emitting device 10 to have a peak inflection point within the range of 630±2 nanometers and another peak inflection point within the range of 650-690 nanometers. This ensures that both brightness and purity of the light-emitting device 10 are achieved to a certain extent.

[0015] See Table 1, which compares data between the prior art and the light-emitting device 10 provided by this embodiment. The prior art achieves an excellent result of extremely high color purity (e.g., 99%) by simply using a short-wavelength light-emitting chip to excite a long-wavelength red powder (e.g., red powder emitting at a wavelength greater than 650 nanometers). The color coordinates are (0.7063, 0.2900), and the purity reaches 0.989, approaching 99%. However, the brightness is only 10.43. In a large amount of data, the average purity of light-emitting devices manufactured using this technology within a three-step color tolerance range can only be guaranteed to be greater than 97%. In one specific embodiment, the light-emitting device 10 of the present invention, using the same light-emitting chip and operating current density, achieves a brightness of 13.10, significantly improving both luminous efficacy and brightness. Furthermore, the average purity of the light-emitting device 10 manufactured using this technology within the three-step color tolerance range can be guaranteed to be greater than 99%.

[0016] Table 1

[0017]

[0018] Specifically, in one embodiment of the present invention, the first phosphor layer 200 may include, for example, an ultra-narrowband phosphor having an emission wavelength of 630±2 nanometers, and a half-wave width range of less than 30 nanometers. The second phosphor layer 300 may include, for example, a medium-wideband phosphor, and a half-wave width range of 50 to 70 nanometers. In this embodiment, the ultra-narrowband phosphor may be, for example, a fluoride phosphor, specifically, KSF (K2SiF6:Mn 4+ ) phosphor, KGF(K2GeF6:Mn 4+ ) phosphor, KTF(K2TiF6:Mn 4+) phosphors, etc. The medium-wideband phosphors can be, for example, selected from nitride phosphors, silicates, sulfides, a-SiAlON phosphors, etc. In this embodiment, the second phosphor adhesive layer 300 can use, for example, a single medium-wideband phosphor, or can use two or more medium-wideband phosphors of different wavelengths mixed in a certain proportion. When the second phosphor adhesive layer 300 uses only one medium-wideband phosphor, the emission wavelength range of the medium-wideband phosphor is preferably 650 to 690 nanometers. When the second phosphor adhesive layer 300 uses two or more medium-wideband phosphors of different wavelengths mixed in a certain proportion, the emission wavelength range of the medium-wideband phosphors that can be used is 630 to 700 nanometers, and at least one of the medium-wideband phosphors has an emission wavelength range of 650 nanometers or more. In other words, although the emission wavelength of the second fluorescent glue layer 300 is mentioned above as being 650-690 nanometers, the selection of medium- and wide-bandwidth phosphors is not limited to those with an emission wavelength of 650-690 nanometers. The second fluorescent glue layer 300 can include multiple phosphors with an emission wavelength of 630-700 nanometers. When the mixed phosphors have a peak wavelength in the emission spectrum between 650-690 nanometers after excitation, this constitutes the second fluorescent glue layer 300 with an emission wavelength of 650-690 nanometers as described in the present invention. An emission wavelength of the second fluorescent glue layer 300 that is too short will result in reduced color purity, while an emission wavelength that is too long will affect brightness. In another embodiment of this embodiment, the first fluorescent glue layer 200 can include a medium- and wide-bandwidth phosphor with an emission wavelength in the range of 650-690 nanometers, and the second fluorescent glue layer 300 can include an ultra-narrowband phosphor with an emission wavelength of 630±2 nanometers. Of course, this embodiment is not limited to this. The first phosphor layer 200 and the second phosphor layer 300 include a medium-bandwidth phosphor with an emission wavelength in the range of 650 to 690 nanometers and an ultra-narrowband phosphor with an emission wavelength of 630 ± 2 nanometers. For ease of explanation, the following description will only focus on the currently preferred embodiment. By combining the ultra-narrowband phosphor with an emission wavelength of 630 ± 2 nanometers with the phosphor with an emission wavelength of 630 to 700 nanometers, the intensity of the orange-yellow portion of the luminous spectrum of the light-emitting device 100, which is close to red light, can be controlled, thereby improving the purity of the red light. Furthermore, the ultra-narrowband phosphor is preferably used in an amount of 20% to 70% of the total weight of all phosphors, thereby improving the brightness of the red light.

[0019] Conventional phosphor-converted LED lighting products mix all phosphors with silica gel to form a fluorescent glue, which is then directly encapsulated onto an LED light-emitting chip. The light-emitting chip, such as a blue light chip, excites the fluorescent glue and emits mixed light. However, for special colors of light with high purity requirements, such as pure red light, a red phosphor with a longer emission wavelength is required to ensure the color point of the red light, and a larger amount of red phosphor is required to absorb all the light emitted by the light-emitting chip to ensure the final color purity. The longer the emission wavelength of the red or orange phosphor, the worse the luminous efficiency. The higher the red light purity requirement, the greater the demand for the wavelength and amount of red phosphor. As the demand for red light wavelength and amount increases, the luminous efficiency and brightness of the entire light-emitting unit will drop sharply, failing to meet the requirements of green lighting. In addition, based on the requirement for product miniaturization, excessive phosphor dosage may cause operational difficulties and affect product yield. The light-emitting device 10 provided in this embodiment uses a layered dispensing process to separate phosphors with different characteristics into fluorescent glue, which is arranged in a specific manner to reduce the total amount of phosphor used and improve the brightness of the light-emitting device while ensuring color purity.

[0020] See also Figure 1 and Figure 2 The height of the first fluorescent adhesive layer 200 in the die-bonding area S1 does not exceed 125% of the thickness of the light-emitting chip 100. The die-bonding area S1 is the longitudinal space corresponding to the light-emitting chip 100. The height of the first fluorescent adhesive layer 200 in the die-bonding area S1 is the sum of the thickness of the first fluorescent adhesive layer 200 and the portion surrounding the light-emitting chip 100 (i.e., the thickness of the light-emitting chip 100), and the thickness of the first fluorescent adhesive layer 200 located on the upper surface of the light-emitting chip 100.

[0021] Specifically, see Figure 1 The first fluorescent adhesive layer 200 is disposed around the light-emitting chip 100, and the first fluorescent adhesive layer 200 does not cover the upper surface of the light-emitting chip 100. Specifically, the upper surface of the light-emitting chip 10 may not be provided with the first fluorescent adhesive layer 200, for example. In this embodiment, the light-emitting device 10 may further include a support cup 400, the light-emitting chip 100 is disposed at the bottom of the support cup 400, and the first fluorescent adhesive layer 200 and the second fluorescent adhesive layer 300 are both disposed within the support cup 400. The first fluorescent adhesive layer 200 is disposed around the light-emitting chip 100. Based on the current dispensing process, the first fluorescent adhesive layer 200 may climb along the cup wall of the support bowl 400, so that the horizontal height of the portion of the first fluorescent adhesive layer 200 close to the cup wall may exceed the upper surface of the light-emitting chip 100. However, in this embodiment, the longitudinal space where the chip is located is regarded as the die-bonding area S1. Excluding the portion where the first fluorescent adhesive layer 200 climbs along the cup wall of the support bowl 400, the horizontal height of the first fluorescent adhesive layer 200 is less than or equal to the thickness of the light-emitting chip 100.

[0022] See also Figure 2The first fluorescent glue layer 200 can also be arranged, for example, around the light-emitting chip 100 and covering the upper surface of the light-emitting chip 100. The thickness of the first fluorescent glue layer 200 covering the upper surface of the light-emitting chip 100 is less than or equal to 25% of the thickness of the light-emitting chip 100. Furthermore, the thickness of the first fluorescent glue layer 200 covering the upper surface of the light-emitting chip 100 is less than or equal to 15% of the thickness of the light-emitting chip 100. Through such an arrangement, a better excitation effect can be achieved, and hidden dangers such as wire collapse caused by the glue hitting the wire can be avoided. In other words, in this embodiment, the horizontal height of the first fluorescent glue layer 200 in the crystal bonding area is less than or equal to 125% of the thickness of the light-emitting chip 100, and more preferably less than or equal to 115% of the thickness of the light-emitting chip 100. Such a design can ensure that the second fluorescent glue layer 300 has sufficient operating space in the vast majority of miniaturized bracket bowls on the market, which helps to achieve the purpose of the present invention.

[0023] Furthermore, the ultra-narrowband phosphor can be, for example, evenly distributed within the first fluorescent adhesive layer 200. This even distribution of the ultra-narrowband phosphor within the first fluorescent adhesive layer 200 can provide a better excitation effect. The second fluorescent adhesive layer 300 can, for example, have a layered structure. The second fluorescent adhesive layer 300 can, for example, include a precipitate layer 310 proximate to the first fluorescent layer 200 and a clear adhesive layer 320 disposed on the precipitate layer 310, away from the first fluorescent adhesive layer 200. Specifically, the clear adhesive layer 320 is located on the side of the precipitate layer 310 away from the light-emitting chip 100. Furthermore, the thickness of the clear adhesive layer 320 is less than that of the precipitate layer 310. To put it another way, the light-emitting device of the present invention can have a longitudinal cross-section, and the fluorescent adhesive can, for example, be shown as a three-layer structure, including the first fluorescent adhesive layer 200, the precipitate layer 310, and the clear adhesive layer 320. The precipitate layer 310 is located between the first fluorescent adhesive layer 200 and the clear adhesive layer 320, and the clear adhesive layer 320 is located on the side of the precipitate layer 310 away from the light-emitting chip 100. The second fluorescent adhesive layer 300 is thicker than the first fluorescent adhesive layer 200; the thickness of the precipitated layer 310 is thicker than the first fluorescent adhesive layer 200, and the thickness of the precipitated layer 310 is thicker than the thickness of the clear adhesive layer 320. It should be noted that the clear adhesive layer 320 is not completely free of fluorescent adhesive; it is just that the content / concentration of visible fluorescent powder in the clear adhesive layer is lower than that in the precipitated layer.

[0024] For example, when preparing the first fluorescent glue layer 200, it can be centrifuged at a low speed for a short time, for example, by semi-centrifugation. In this way, the surface of the fluorescent glue can be roughly leveled, but the ultra-narrow wave phosphor will not settle to the bottom, so that the ultra-narrow wave phosphor is evenly distributed in the first fluorescent glue layer 200. When preparing the second fluorescent glue layer 300, for example, a full centrifugation method can be used for long-term high-speed centrifugation. After full centrifugation, the lower layer of the second fluorescent glue layer 300 is precipitated to form a precipitation layer 310, and the upper layer forms a clear glue layer 320, so that the fluorescent glue can be better leveled and cover the lower first fluorescent glue layer 200. Leveling can improve the stability of subsequent operations, improve the concentration of color points, and improve the color uniformity at different angles. As a result, the flatness of the interface between the second fluorescent glue layer 300 and the first fluorescent glue layer 200 is greater than the flatness of the interface between the precipitation layer 310 and the clear glue layer 320. According to Figure 1 and Figure 2 As can be seen, the light-emitting device of the present invention has a longitudinal cross-section showing that the curvature of the boundary between the second fluorescent adhesive layer 300 and the first fluorescent adhesive layer 200 (or the boundary between the precipitated layer 310 and the first fluorescent adhesive layer 200) is greater than the curvature of the boundary between the precipitated layer 310 and the clear adhesive layer 320. In other words, the boundary between the precipitated layer 310 and the clear adhesive layer 320 is smoother than the boundary between the second fluorescent adhesive layer 300 and the first fluorescent adhesive layer 100. The above-described operation of the first fluorescent adhesive layer 200 and the second fluorescent adhesive layer 300 facilitates more stable mass production of light-emitting devices 100 with high color purity and brightness, resulting in a higher production yield and less color tolerance variation in mass-produced light-emitting devices 100.

[0025] In this embodiment, the weight ratio of the ultra-narrowband phosphor to the first phosphor adhesive layer 300 is in the range of 30% to 70%, and the weight ratio of the medium-wideband phosphor to the second phosphor adhesive layer 300 is in the range of 35% to 75%. These weight ratios can be adjusted based on the specific selection of the light-emitting chip 100, the ultra-narrowband phosphor, and the medium-wideband phosphor. When the adjusted light-emitting device 10 has the following characteristics in its luminous spectrum, the purpose of the present invention can be achieved. Figure 3 , Figure 3The luminous spectrum of the light-emitting device 10 provided in this embodiment. The normalized intensity value of the luminous spectrum in the range below 580 nanometers is less than or equal to 6%; preferably, this intensity value may be less than or equal to 4%; more preferably, it may be less than or equal to 2%. By adjusting the specific combination of the light-emitting chip 100 and the phosphor according to the specific requirements of the luminous spectrum of the light-emitting device 10, it can be ensured that the blue light emitted by the light-emitting chip 100 is fully absorbed by the first fluorescent glue layer 200 and the second fluorescent glue layer 300, thereby avoiding affecting the purity of the red light emitted by the light-emitting device 10. Simply put, in some embodiments, the color coordinates of the light emitted by the light-emitting chip 100 that excites the first fluorescent glue layer 200 and the second fluorescent glue layer 300 are located at (x, y), where x>0.6850 and y<0.3050, which meets the basic requirements of high color purity red light.

[0026] Furthermore, the emission spectrum of the light-emitting device 10 may, for example, have a first peak inflection point Wp1 and a second peak inflection point Wp2. The wavelength range of the first peak inflection point Wp1 is 630 ± 2 nanometers, and the wavelength range of the second peak inflection point Wp2 is 645 to 700 nanometers. In most embodiments, the second peak inflection point Wp2 is typically the peak value of the light-emitting device 100. In a preferred embodiment, the intensity of the first peak inflection point Wp1 is less than the intensity of the second peak inflection point Wp2. This ensures that the ultra-narrowband phosphor with a shorter wavelength is not excessively used, which would cause the color coordinates (x, y) of the light-emitting device 100 to deviate from the basic requirements of x > 0.6850 and y < 0.3050, thereby affecting the red light purity. Normalization is performed with the intensity of the second peak inflection point Wp2 as 100%. The normalized intensity of the first peak inflection point Wp1 is less than 95%, preferably between 75% and 95%, achieving an optimal balance between color purity and brightness. In other words, the intensity of the first emission wavelength of the light emitting device 100 of this embodiment is less than the intensity of the second emission wavelength.

[0027] In some embodiments, the emission spectrum of the light-emitting device 10 may further include a third peak inflection point Wp3 located between the first peak inflection point Wp1 and the second peak inflection point Wp2, with the wavelength of the third peak inflection point Wp3 ranging from 635±2 nanometers. In other embodiments, the emission spectrum of the light-emitting device 10 may further include a fourth peak inflection point Wp4 located between the first peak inflection point Wp1 and the second peak inflection point Wp2, with the wavelength of the fourth peak inflection point Wp4 ranging from 645±2 nanometers. The normalized intensity of the third peak inflection point Wp3 may be 75% to 95%, and the normalized intensity of the fourth peak inflection point Wp4 may be 80% to 95%.

[0028] In summary, the light-emitting device 10 of the present invention utilizes the first and second phosphor layers 200, the light-emitting chip 100, the ultra-narrowband phosphor, and the medium-wideband phosphor to interact with each other, thereby ensuring that at least one of the first and second phosphor layers has a first emission wavelength within the range of 630±2 nanometers (reflected as a first peak inflection point Wp1 in the emission spectrum), and at least one of the first and second phosphor layers has a second emission wavelength within the range of 650-690 nanometers (reflected as a second peak inflection point Wp2 in the emission spectrum). This results in light emitted by the light-emitting device 10 having a color purity exceeding 99% and high brightness.

[0029] In addition, it can be understood that the aforementioned embodiments are merely illustrative descriptions of the present invention. Under the premise that the technical features do not conflict, the structures do not contradict, and the purpose of the invention of the present invention is not violated, the technical solutions of the various embodiments can be arbitrarily combined and used in combination.

[0030] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A light emitting device, characterized in that: include: Light-emitting chip; a first fluorescent adhesive layer surrounding the light-emitting chip; as well as a second fluorescent adhesive layer, disposed on the first fluorescent adhesive layer and covering the light-emitting chip; The horizontal height of the first fluorescent glue layer in the crystal-fixing area does not exceed 125% of the thickness of the light-emitting chip, and the crystal-fixing area is the longitudinal space corresponding to the light-emitting chip.

2. The light emitting device according to claim 1, wherein At least one of the first fluorescent glue layer and the second fluorescent glue layer has a first emission wavelength in the range of 630±2 nanometers, and at least one of the first fluorescent glue layer and the second fluorescent glue layer has a second emission wavelength in the range of 650 to 690 nanometers, and the intensity of the first emission wavelength is less than the intensity of the second emission wavelength.

3. The light emitting device according to claim 2, wherein: The first fluorescent adhesive layer does not cover the upper surface of the light-emitting chip.

4. The light emitting device according to claim 2, wherein: The first fluorescent glue layer is arranged around the light emitting chip and covers the upper surface of the light emitting chip. The thickness of the first fluorescent glue layer covering the upper surface of the light emitting chip is less than or equal to 25% of the thickness of the light emitting chip.

5. The light emitting device according to claim 2, wherein: The second fluorescent adhesive layer has a layered structure, and includes a precipitation layer close to the first fluorescent layer and a clear adhesive layer located on the precipitation layer and away from the first fluorescent adhesive layer.

6. The light emitting device according to claim 5, wherein The thickness of the clear glue layer is smaller than that of the precipitation layer, and the thickness of the first fluorescent glue layer is smaller than that of the precipitation layer.

7. The light emitting device according to claim 1, wherein The light emitting device has a light emitting spectrum, and the normalized intensity of the light emitting spectrum below 580 nanometers is less than or equal to 6%.

8. The light emitting device according to any one of claims 1 to 7, wherein: The light-emitting spectrum of the light-emitting device has a first peak inflection point and a second peak inflection point. The wavelength range of the first peak inflection point is 630±2 nanometers, the wavelength range of the second peak inflection point is 650-690 nanometers, and the intensity ratio of the first peak inflection point to the second peak inflection point is less than 95%.

9. The light emitting device according to claim 8, wherein The luminous spectrum of the light-emitting device also includes a third peak inflection point and a fourth peak inflection point. The wavelength value of the third peak inflection point is 635±2 nanometers, and the wavelength value of the fourth peak inflection point is 645±2 nanometers; the normalized intensity range of the third peak inflection point is 75% to 95%, and the normalized intensity range of the fourth peak inflection point is 80% to 95%.

10. The light emitting device according to claim 1, wherein The color coordinates of the light emitted by the light emitting device fall at (x, y), where x>0.6850 and y<0.3050.

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