LED light source

Abstract

This application provides an LED light source, belonging to the field of LED lighting technology, comprising at least two LED beads. Each LED bead includes an LED chip and a photosensitive element mounted on a substrate. The LED chip and photosensitive element are electrically connected, and the voltage difference between the LED chips of any two LED beads under low current is less than a predetermined value. This application incorporates a photosensitive element within each LED bead, electrically connecting the corresponding LED chip to the photosensitive element. The photosensitive element can change its parameters according to the brightness of the LED chip, thereby adaptively adjusting the current flowing through the LED chip and thus adjusting its brightness, improving the brightness uniformity of the LED bead (especially under low current). Simultaneously, the voltage value under low current is used to screen all LED chips in the LED light source, resulting in good consistency among all LED chips. All LED beads can maintain consistent brightness even under low current, further improving the brightness uniformity of the LED light source.

Description

Technical Field

[0001] This application relates to the field of LED lighting, specifically to an LED light source. Background Technology

[0002] LED chips are characterized by high brightness, low energy consumption, and long lifespan, meeting the needs of various scenarios and are widely used in displays, billboards, interior and exterior decoration, automotive lighting, and other fields. Currently, most LED light sources on the market are composed of multiple LED chips connected in series and parallel in different combinations. To avoid the undesirable phenomenon of inconsistent brightness in LED light sources, the consistency of the luminous brightness of LED chips is required to be very high.

[0003] In certain special locations, to align with the concept of green environmental protection and energy conservation, LED light sources need to maintain a low-brightness state during non-operational periods. For example, in underground parking garages, LED light sources need to remain bright when vehicles pass by, and low-brightness at other times. Conventional LED chips are very bright at high brightness, and the light from adjacent LED chips compensates for each other, preventing noticeable differences in brightness. However, at low brightness, the subtle differences in brightness within the LED chips become particularly noticeable, resulting in a visually significant unevenness in brightness and poor uniformity, thus affecting lighting performance. Utility Model Content

[0004] In view of this, the embodiments of this application aim to provide an LED light source to solve the problems of poor brightness uniformity in existing LED light sources.

[0005] This application provides an LED light source, including at least two LED beads. Each LED bead includes a substrate, an LED chip, and a photosensitive element. The LED chip and the photosensitive element are both located on the substrate and are electrically connected. The difference in voltage values ​​of the LED chips of any two LED beads under low current is less than a predetermined value.

[0006] In some embodiments, the photosensitive element is a photosensitive device or a photosensitive chip, and the photosensitive device or the photosensitive chip is connected in parallel with the corresponding LED chip.

[0007] In some embodiments, the photosensitive element includes a photosensitive surface and electrodes, and the LED bead further includes a reflective layer that at least covers the exposed surfaces of the photosensitive element other than the photosensitive surface and the electrodes.

[0008] In some embodiments, the reflective layer also covers non-conductive areas of the exposed surface of the substrate.

[0009] In some embodiments, the reflective layer is at least one of a white adhesive layer, a metal reflective layer, and a dielectric reflective layer.

[0010] In some embodiments, the thickness of the reflective layer is less than or equal to 0.17 mm.

[0011] In some embodiments, the LED chip is bonded to the substrate by a first die bond layer, the first die bond layer being transparent; and / or, the photosensitive element is fixed to the substrate by a second die bond layer, the second die bond layer being white.

[0012] In some embodiments, the voltage value under low current is the voltage value of the LED chip under a predetermined current, wherein the predetermined current is less than or equal to the minimum turn-on current of the LED chip and 10% of the rated current of the LED chip.

[0013] In some embodiments, the predetermined value is less than or equal to 0.05V.

[0014] In some embodiments, the LED light source has at least 10 parallel light-emitting paths, and each light-emitting path has at least two LED beads connected in series.

[0015] This application provides an LED light source, including at least two LED beads. Each LED bead includes an LED chip and a photosensitive element mounted on a substrate. The LED chip and the photosensitive element are electrically connected. The difference in voltage values ​​of the LED chips of any two LED beads under low current is less than a predetermined value. In this application, a photosensitive element is provided in each LED bead, and the corresponding LED chip is electrically connected to the photosensitive element. The photosensitive element can change its parameters according to the brightness of the LED chip, thereby adaptively adjusting the current flowing through the LED chip, and thus adjusting the brightness of the LED chip, improving the brightness uniformity among the LED beads (especially under low current). At the same time, since the difference in voltage values ​​of the LED chips of any two LED beads under low current is less than a predetermined value, it is equivalent to using the voltage values ​​under low current to screen all the LED chips in the LED light source, resulting in good consistency among all the LED chips. All LED beads can maintain consistent brightness even under low current, improving the brightness uniformity of the LED light source. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of bonding LED chips and photosensitive elements onto a substrate, provided in an embodiment of this application.

[0017] Figure 2This is a schematic diagram of a structure in which a blocking adhesive layer is provided on the top surface of the electrode and the photosensitive surface of a photosensitive element, as provided in an embodiment of this application.

[0018] Figure 3 This is a schematic diagram of a structure in which a layer of white glue is molded onto a photosensitive element as a reflective layer, as provided in an embodiment of this application.

[0019] Figure 4 This is a schematic diagram of the structure for debonding the barrier adhesive layer provided in an embodiment of this application.

[0020] Figure 5 This is a schematic diagram of the structure of an LED lamp bead in an LED light source provided in an embodiment of this application.

[0021] Figure 6 This is a schematic diagram showing the distribution of LED chips and photosensitive elements on an LED bead provided in an embodiment of this application.

[0022] The attached figures are labeled as follows:

[0023] 100-Substrate; 101-Bowl; 201-LED chip; 211-Second electrode; 221-First die bond layer; 202-Photosensitive element; 212-First electrode; 222-Second die bond layer; 232-Photosensitive surface; 300-Barrier layer; 400-Reflective layer; 500-Light conversion layer. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] This application provides an LED light source, which can be a direct-lit LED light source or a side-lit LED light source. The LED light source includes at least two LED beads, and the LED beads in the LED light source can be distributed in one or more rows. Figure 5 This is a schematic diagram of the structure of an LED lamp bead in an LED light source provided in an embodiment of this application. Figure 6 This is a schematic diagram showing the distribution of the LED chip 201 and photosensitive element 202 on an LED lamp bead provided in an embodiment of this application. Figure 5 and Figure 6As shown, an LED bead includes an LED chip 201 and a photosensitive element 202 located on a substrate 100. The LED chip 201 and the photosensitive element 202 are electrically connected, and the voltage difference of the LED chips 201 of any two LED beads under low current is less than a predetermined value. This application provides a photosensitive element 202 in each LED bead, electrically connecting the corresponding LED chip 201 to the photosensitive element 202. The photosensitive element 202 can change its parameters according to the brightness of the LED chip 201, thereby adaptively adjusting the current flowing through the LED chip 201, and thus adjusting the brightness of the LED chip 201, improving the brightness uniformity among LED beads (especially under low current). Simultaneously, since the voltage difference of the LED chips 201 of any two LED beads under low current is less than a predetermined value, it is equivalent to using the voltage value under low current to filter all LED chips 201 in the LED light source, resulting in better consistency among all LED chips 201. All LED beads can maintain consistent brightness even under low current, improving the brightness uniformity of the LED light source.

[0026] Specifically, the substrate 100 can be made of ceramic materials (including one or more of AlN, Al2O3, SiO, SiO2, Si3N4, and SiON) or metallic materials (including aluminum or copper). The substrate 100 has a ring-shaped cup 101 disposed on it. The cup 101 can be made of thermosetting epoxy resin, thermosetting silicone, or thermoplastic plastic. Electrical connectors such as plugs and pads can be disposed within the substrate 100. The LED chip 201 and the photosensitive element 202 can both be disposed within the cup 101. The cup 101 also has a light conversion layer 500 that covers the LED chip 201 and the photosensitive element 202 and fills the space within the cup 101.

[0027] Please continue reading. Figure 5 The inner wall of the cup 101 is inclined, and the opening width of the cup 101 on the side closer to the substrate 100 is smaller than the opening width on the side farther from the substrate 100. Alternatively, the cup 101 can be understood as a frustum-shaped cone with a trapezoidal cross-section, its diameter gradually increasing from bottom to top, resulting in an inclined inner wall. In this way, when light emitted from the LED chip 201 shines on the inner wall of the cup 101, the inner wall can reflect the light onto the light conversion layer 500, improving light utilization, avoiding light energy waste, and reducing power consumption. Of course, the cup 101 may not be provided on the substrate 100. In this case, the light conversion layer 500 can be hemispherical or other shapes, and can also cover the substrate 100, the LED chip 201, and the photosensitive element 202.

[0028] Furthermore, the light emitted by the LED chip 201 can be blue light, violet light, or ultraviolet light, etc. Based on this, the LED chip 201 can be a blue LED chip 201, such as a GaN-based LED chip 201 that emits blue light. The LED chip 201 can also be a violet or ultraviolet LED chip 201. An LED bead may include only a single LED chip 201, but in some embodiments, at least two LED chips 201 may be provided.

[0029] In some embodiments, the LED chip 201 can be die-bonded onto the substrate 100 using a first die-bonding adhesive layer 221, and then the LED chip 201 is interconnected with electrical connectors within the substrate 100 using leads. The first die-bonding adhesive layer 221 is typically located between the bottom of the LED chip 201 and the substrate 100, but the first die-bonding adhesive layer 221 may also overflow from the bottom of the LED chip 201, thereby covering the sidewalls of the LED chip 201. To avoid the first die-bonding adhesive layer 221 blocking the light emitted by the LED chip 201, the color of the first die-bonding adhesive layer 221 is preferably transparent.

[0030] In some embodiments, the LED chip 201 can also be flip-chip soldered onto the substrate 100, which can free it from the constraints of leads and die bond, resulting in the LED chip 201 having high thermal conductivity, low thermal resistance, and the ability to withstand high current, as well as stronger reliability, higher luminous flux maintenance rate, and longer service life.

[0031] In some embodiments, the photosensitive element 202 can be a photosensitive device or a photosensitive chip. For example, the photosensitive device can be a photoresistor or a photodiode, while the photosensitive chip can be a chip packaged together with a photoresistor or photodiode and circuits such as a current amplifier. Compared to using a photosensitive device alone as the photosensitive element 202, using a photosensitive chip as the photosensitive element 202 can improve performance such as accuracy and sensitivity. Typically, the photosensitive device or photosensitive chip is connected in parallel with the corresponding LED chip 201. When the brightness of the LED chip 201 fluctuates, the light energy received by the photosensitive surface 232 of the photosensitive element 202 changes accordingly. The photosensitive element 202 can change its own parameters (such as resistance value) to change the current through the LED chip 201, thereby adjusting the brightness of the LED chip 201. By adaptively adjusting the current through the LED chip 201, the brightness uniformity of the LED beads is improved. Especially when all LED chips are dimly lit, taking a photoresistor as an example, if the brightness of a certain LED chip 201 is too low, a noticeable dark area will appear in the LED light source. At this time, the light-sensitive surface 232 of the photoresistor receives less light energy, its resistance increases, the current through the photoresistor decreases, and the current through the LED chip 201 increases, which can improve the brightness of the LED chip 201 and prevent the dark area from appearing. Conversely, if the brightness of a certain LED chip 201 is too high, a noticeable bright spot will appear in the LED light source. At this time, the light-sensitive surface 232 of the photoresistor receives more light energy, its resistance decreases, the current through the photoresistor increases, and the current through the LED chip 201 decreases, which can reduce the brightness of the LED chip 201 and prevent the bright spot from appearing.

[0032] In some embodiments, when the photosensitive element 202 is a photosensitive chip, it can be die-bonded onto the substrate 100 using a second die-bonding adhesive layer 222. The photosensitive element 202 is interconnected with electrical connectors within the substrate 100 via leads, and finally electrically connected to the LED chip 201 via metal wires on the substrate 100. The second die-bonding adhesive layer 222 is typically located between the bottom of the photosensitive element 202 and the substrate 100. However, the second die-bonding adhesive layer 222 may also overflow from the bottom of the photosensitive element 202, thereby covering the sidewalls of the photosensitive element 202. To ensure that the light emitted by the LED chip 201 passes through the second die-bonding adhesive layer 222 and is absorbed by the molding compound of the photosensitive element 202, the color of the second die-bonding adhesive layer 222 is preferably white, thereby reflecting some of the light emitted by the LED chip 201, reducing light loss, and improving luminous efficiency.

[0033] In some embodiments, the photosensitive element 202 can also be flip-chip bonded to the substrate 100. This eliminates the constraints of leads and die-attach adhesive, resulting in a photosensitive element 202 with high thermal conductivity, low thermal resistance, and the ability to withstand high currents, thus exhibiting stronger reliability and a longer lifespan. However, it should be noted that the photosensitive surface 232 of the photosensitive element 202 needs to be located on the surface of the photosensitive element 202 facing away from the substrate 100. Of course, when the photosensitive element 202 is a photosensitive device, it can also be directly bonded to the substrate 100.

[0034] Based on this, the difference in voltage values ​​of LED chips 201 under low current for any two LED beads is less than a predetermined value. Since the voltage value of LED chip 201 under low current is the forward voltage value corresponding to LED chip 201 when a small forward current (usually less than 20μA, for example, 1μA) is applied, it is also called VFL (Forward Voltage Low), VF4, or Vfin. It can reflect the consistency capability, epitaxial (PN junction part) defect status, and ohmic contact status of LED chip 201. If the voltage values ​​of LED chips 201 of any two LED beads in the LED light source are small in difference under low current, the brightness consistency of all LED beads in the LED light source is good under low current dim lighting conditions, thereby further improving the brightness uniformity of the LED light source. Meanwhile, the voltage value under low current can also be called the voltage value under micro current or the voltage value under minute current. Usually, when a current near its rated current (IF) is applied to the LED chip 201, the forward voltage of the LED chip 201 is also near its rated voltage (VF). However, the LED chip 201 will generate heat at this time. The amount of heat in the area where the LED chip 201 is located will affect the light emission of the LED chip 201. However, the LED chip 201 has basically no heat effect under low current. Therefore, the influence of heat on the LED chip 201 can be shielded, so that the voltage value under low current can reflect the consistency of the LED chip 201.

[0035] In some embodiments, the predetermined value is less than or equal to 0.05V, but should not be limited thereto.

[0036] It should be noted that the voltage value under low current is the voltage value of LED chip 201 at a predetermined current. The predetermined current needs to be between the minimum turn-on current of LED chip 201 and 10% of the rated current of LED chip 201, so as to ensure that the brightness emitted by the LED bead is consistent when it is turned on at a low turn-on current. For example, the minimum turn-on current of LED chip 201 can be 0.05μA and the rated current is 20mA. Then the predetermined current (i.e., low current) can be greater than 0.05μA and less than 2mA, and can be 1μA, 20μA, 1mA, etc., but is not limited to this.

[0037] It is understandable that, regardless of whether the photosensitive element 202 is a photosensitive device or a photosensitive chip, the periphery of the photosensitive element 202 may absorb a significant amount of light. Adding a photosensitive element 202 to each LED chip may lead to a decrease in the overall luminous flux of the LED chip, which may contradict the current market trend of high luminous efficiency. Therefore, please continue reading... Figure 5 The LED chip may also include a reflective layer 400, which can cover the unused area surrounding the photosensitive element 202. The reflective layer 400 reflects the light emitted by the LED chip 201, achieving the effect of not weakening the overall light output, reducing light loss and improving luminous efficiency. Specifically, the photosensitive element 202 typically has a photosensitive surface 232 and electrodes (…). Figure 5 The first electrode 212), the reflective layer 400 at least covers the exposed surface of the photosensitive element 202 except for the photosensitive surface 232 and the electrode (first electrode 212), Figure 5 The photosensitive surface 232 and the electrode (first electrode 212) of the photosensitive element 202 are both on its top surface. Therefore, the reflective layer 400 covers the sidewalls and the empty area on the top surface of the photosensitive element 202. However, this should not be the limitation. The electrode (first electrode 212) of the photosensitive element 202 can also be in other positions, which will not be listed here.

[0038] In some embodiments, the reflective layer 400 may also cover non-conductive areas of the exposed surface of the substrate 100, thereby preventing the substrate 100 from absorbing light emitted by the LED chip 201, further reducing light loss and improving luminous efficiency. Specifically, there may be some pads and metal lines on the substrate 100, and the reflective layer 400 may cover the exposed areas of the substrate 100 other than the pads and metal lines.

[0039] Furthermore, the reflective layer 400 can be at least one of a white adhesive layer, a metal reflective layer, and a dielectric reflective layer. It should be noted that when the reflective layer 400 is a metal reflective layer, the reflective layer 400 needs to maintain a certain distance from the electrodes of the photosensitive element 202 and the conductive areas on the substrate 100, so as to avoid short circuits.

[0040] Optionally, the thickness of the reflective layer 400 can be less than or equal to 0.17 mm. Within this thickness range, the reflective layer 400 will not significantly affect the size and weight of the LED beads, and the reflective layer 400 is also relatively easy to form.

[0041] Furthermore, the light conversion layer 500 in this application can be formed by mixing a colloid and a light conversion material. The light conversion material can be quantum dots or phosphors, and the colloid can be materials such as silicone. That is, the light conversion layer 500 can be a quantum dot layer or a phosphor layer. Compared with the traditional white light solution that uses a layered dispensing method to simultaneously improve the color rendering index and luminous efficacy, the LED beads in this application can use quantum dots instead of phosphors. The process is easy to control, the yield is high, and it is not affected by high or low color temperatures, thus simultaneously improving light extraction efficiency, color rendering index, and reliability.

[0042] Furthermore, since the more LEDs in an LED light source, the more pronounced the subtle differences in brightness between the LEDs themselves become, this application is particularly suitable for use in LED light sources with a large number of LEDs. For example, the LED light source in this application can have at least 10 parallel light-emitting paths, with at least two LEDs connected in series in each light-emitting path.

[0043] Based on this, some embodiments of this application also provide a method for preparing the LED beads in the above-mentioned LED light source. Figures 1-5 This is a schematic diagram of the corresponding steps in the method for preparing an LED bead according to an embodiment of this application. Next, we will combine... Figures 1-5 The preparation method of LED lamp beads is described in detail.

[0044] like Figure 1 As shown, a substrate 100 is provided. The substrate 100 can be made of ceramic materials (including one or more of AlN, Al2O3, SiO, SiO2, Si3N4, and SiON) or metallic materials (including aluminum or copper). A cup 101, which is annular in shape and disposed on the substrate 100, is provided on the substrate 100. The cup 101 can be made of thermosetting epoxy resin, thermosetting silicone, or thermoplastic plastic, etc. Electrical connectors such as plugs and solder pads can be disposed within the substrate 100.

[0045] Please continue reading. Figure 1 An LED chip 201 and a photosensitive element 202 are die-bonded onto a substrate 100, both located within a bowl-shaped cup 101. The LED chip 201 is die-bonded onto the substrate 100 using a first die-bonding adhesive layer 221, while the photosensitive element 202 is die-bonded onto the substrate 100 using a second die-bonding adhesive layer 222. The first die-bonding adhesive layer 221 is preferably transparent, and the second die-bonding adhesive layer 222 is preferably white.

[0046] In some embodiments, the LED chip 201 can also be flip-chip bonded to the substrate 100. This eliminates the constraints of leads and die-attach adhesive, resulting in high thermal conductivity, low thermal resistance, and the ability to withstand high currents, leading to enhanced reliability, higher luminous flux maintenance, and a longer lifespan. The photosensitive element 202 can also be flip-chip bonded to the substrate 100. This eliminates the constraints of leads and die-attach adhesive, resulting in high thermal conductivity, low thermal resistance, and the ability to withstand high currents, leading to enhanced reliability and a longer lifespan. However, it should be noted that the photosensitive surface 232 of the photosensitive element 202 needs to be located on the surface of the photosensitive element 202 facing away from the substrate 100. Of course, when the photosensitive element 202 is a photosensitive device, it can also be directly bonded to the substrate 100.

[0047] like Figure 2 As shown, a barrier adhesive layer 300 is disposed on the top surface of the electrode (first electrode 212) and the photosensitive surface 232 of the photosensitive element 202. The barrier adhesive layer 300 can be a photosensitive film or a thermally degradable film. The thickness of the barrier adhesive layer 300 cannot be made very thin; generally speaking, the thickness of the barrier adhesive layer 300 is greater than or equal to 0.17 mm.

[0048] like Figure 3 As shown, a layer of white adhesive is molded onto the photosensitive element 202 as a reflective layer 400. Since the top surface of the electrode (first electrode 212) of the photosensitive element 202 and the photosensitive surface 232 have a blocking adhesive layer 300, the reflective layer 400 will cover the exposed surface of the photosensitive element 202 except for the photosensitive surface 232 and the electrode.

[0049] In some embodiments, the reflective layer 400 may also cover the non-conductive areas of the exposed surface of the substrate 100. In this case, when the barrier adhesive layer 300 is formed, the barrier adhesive layer 300 may also cover the conductive areas of the exposed surface of the substrate 100 and other areas where the reflective layer 400 is not desired to be formed. When white adhesive is molded on the photosensitive element 202, white adhesive is also molded on the non-conductive areas of the exposed surface of the substrate 100, so that the formed reflective layer 400 covers the exposed surface of the photosensitive element 202 except for the photosensitive surface 232 and the electrode (first electrode 212) and the non-conductive areas of the exposed surface of the substrate 100.

[0050] It should be noted that the reflective layer 400 is not limited to being formed by compression molding. When the material of the reflective layer 400 is changed, the reflective layer 400 can also be formed by other methods.

[0051] It should be noted that the thickness of the reflective layer 400 needs to be less than or equal to the thickness of the blocking adhesive layer 300 to avoid the problem that the blocking adhesive layer 300 cannot be removed. Therefore, the thickness of the reflective layer 400 can be less than or equal to 0.17mm.

[0052] like Figure 4 As shown, the barrier adhesive layer 300 is debonded, releasing its adhesiveness and thus peeling it off from the electrode (first electrode 212) and photosensitive surface 232 of the photosensitive element 202. Afterwards, wire bonding can be performed on the LED chip 201 and the photosensitive element 202. The electrode (second electrode 211) of the LED chip 201 is electrically connected to the substrate 100 via leads, and the electrode (first electrode 212) of the photosensitive element 202 is electrically connected to the substrate 100 via leads.

[0053] like Figure 5 As shown, a light conversion layer 500 is formed inside the bowl 101 and baked and cured. The light conversion layer 500 covers the LED chip 201 and the photosensitive element 202 and fills the space inside the bowl 101.

[0054] After manufacturing individual LED beads, they need to be categorized according to their voltage values ​​under low current and predetermined values. Table 1 shows a categorization method for different LED beads provided in an embodiment of this application. As can be seen from Table 1, for LED chips 201 with different operating voltages, their voltage ranges under the same low current are also different. Therefore, after manufacturing LED beads of the same type, the forward voltage of the LED chip 201 of each LED bead under a forward current of 1μA can be tested. Then, the LED beads of the same type are categorized according to a predetermined value (0.05V) to ensure that the voltage values ​​of the LED chip 201 of all LED beads in the same category under low current do not exceed 0.05V. Afterward, LED beads in the same category can be selected to form an LED light source, ensuring that the difference in voltage values ​​of the LED chip 201 of any two LED beads in the LED light source under low current is less than 0.05V.

[0055] Table 1: Classification Methods for Different LED Beads

[0056]

[0057] In summary, this embodiment provides an LED light source, including at least two LED beads. Each LED bead includes an LED chip 201 and a photosensitive element 202 located on a substrate 100. The LED chip 201 and the photosensitive element 202 are electrically connected, and the difference in voltage values ​​of the LED chips 201 of any two LED beads under low current is less than a predetermined value. In this application, a photosensitive element 202 is provided in each of the LED beads, and the corresponding LED chip 201 is electrically connected to the photosensitive element 202. The photosensitive element 202 can change its own parameters according to the brightness of the LED chip 201, thereby adaptively adjusting the current flowing through the LED chip 201, and thus adjusting the brightness of the LED chip 201, improving the brightness uniformity among the LED beads (especially under low current). At the same time, since the difference in voltage values ​​of the LED chips 201 of any two LED beads under low current is less than a predetermined value, it is equivalent to using the voltage values ​​under low current to screen all the LED chips 201 in the LED light source, so that the consistency of all the LED chips 201 is good, and all the LED beads can ensure consistent brightness even under low current, thus improving the brightness uniformity of the LED light source.

[0058] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0059] It should also be noted that although preferred embodiments have been disclosed above, these embodiments are not intended to limit this application. Any person skilled in the art can make many possible variations and modifications to the technical solutions of this application, or modify them into equivalent embodiments, without departing from the scope of the technical solutions of this application. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this application, without departing from the content of the technical solutions of this application, shall still fall within the scope of protection of the technical solutions of this application.

[0060] It should also be understood that, unless otherwise specified or indicated, the terms “first,” “second,” “third,” etc., in the specification are used only to distinguish the various components, elements, and steps in the specification, and not to indicate the logical or sequential relationships between the various components, elements, and steps.

[0061] Furthermore, it should be recognized that the terminology described herein is used only to describe particular embodiments and is not intended to limit the scope of this application. It must be noted that the singular forms “a” and “an” as used herein include plural bases unless the context clearly indicates the opposite. For example, a reference to “a step” or “an apparatus” means a reference to one or more steps or apparatuses, and may include secondary steps and secondary apparatuses. All conjunctions used should be understood in the broadest sense. Also, the word “or” should be understood as having the definition of logical “or”, not logical “exclusive OR”, unless the context clearly indicates the opposite. Furthermore, implementations of the methods and / or devices in the embodiments of this application may include performing selected tasks manually, automatically, or in combination.

Claims

1. An LED light source, characterized in that, The device includes at least two LED beads, each LED bead comprising a substrate (100), an LED chip (201), and a photosensitive element (202). The LED chip (201) and the photosensitive element (202) are both located on the substrate (100), and the LED chip (201) and the photosensitive element (202) are electrically connected. The difference in voltage values ​​of the LED chips (201) of any two LED beads under low current is less than a predetermined value.

2. The LED light source according to claim 1, characterized in that, The photosensitive element (202) is a photosensitive device or a photosensitive chip, and the photosensitive device or the photosensitive chip is connected in parallel with the corresponding LED chip (201).

3. The LED light source according to claim 1, characterized in that, The photosensitive element (202) includes a photosensitive surface (232) and an electrode. The LED lamp bead also includes a reflective layer (400), which at least covers the exposed surface of the photosensitive element (202) other than the photosensitive surface (232) and the electrode.

4. The LED light source according to claim 3, characterized in that, The reflective layer (400) also covers the non-conductive areas of the exposed surface of the substrate (100).

5. The LED light source according to claim 3 or 4, characterized in that, The reflective layer (400) is at least one of a white adhesive layer, a metal reflective layer, and a dielectric reflective layer.

6. The LED light source according to claim 3 or 4, characterized in that, The thickness of the reflective layer (400) is less than or equal to 0.17 mm.

7. The LED light source according to claim 1, characterized in that, The LED chip (201) is die bonded to the substrate (100) by a first die bond layer (221), the first die bond layer (221) being transparent; and / or, the photosensitive element (202) is fixed to the substrate (100) by a second die bond layer (222), the second die bond layer (222) being white.

8. The LED light source according to claim 1, characterized in that, The voltage value under low current is the voltage value of the LED chip (201) under a predetermined current, wherein the predetermined current is between the minimum turn-on current of the LED chip (201) and 10% of the rated current of the LED chip (201).

9. The LED light source according to claim 1 or 8, characterized in that, The predetermined value is less than or equal to 0.05V.

10. The LED light source according to claim 1, characterized in that, The LED light source has at least 10 parallel light-emitting paths, and each light-emitting path has at least two LED beads connected in series.

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