LED lamp filament and bulb lamp using same

Abstract

An LED filament (100, 300, 400), the LED filament (100, 300, 400) comprising an LED chip unit (202, 204), a light conversion layer (220, 420) and an electrode (210, 212, 410, 412), the light conversion layer (220, 420) covering the LED chip unit (202, 204) and a part of the electrode (210, 212, 410, 412), the color of light emitted after the LED filament (100, 300, 400) is lightened being different from the color of the light conversion layer (220, 420). The LED lamp has the characteristics of uniform light emission and good heat dissipation effect.

Description

LED filament and bulb lamp using the same Technical Field

[0001] The present application relates to the field of lighting, and in particular to an LED filament and a bulb lamp using the LED filament. Background Art

[0002] LEDs, with their environmentally friendly, energy-saving, high-efficiency, and long lifespan, have gained widespread attention in recent years, gradually replacing traditional lighting fixtures. However, traditional LED light sources are directional, unlike traditional lamps that can illuminate at wide angles. Therefore, integrating LEDs into traditional lamps presents challenges depending on the type of fixture.

[0003] In recent years, an LED filament that allows LED light sources to emit light similar to traditional tungsten filament bulbs, achieving 360° full-angle illumination, has been gaining increasing attention in the industry. This type of LED filament is made by connecting multiple LED chips in series and fixing them on a narrow, elongated glass substrate. The entire glass substrate is then wrapped with silicone doped with phosphor and then electrically connected to complete the process. In addition, there is also a type of LED soft filament, which has a similar structure to the above-mentioned filament, but the glass substrate is partially replaced with a flexible substrate (hereinafter referred to as FPC), allowing the filament to have a certain degree of bendability. However, soft filaments made with FPC have disadvantages such as the FPC's thermal expansion coefficient being different from the silicone coating the filament, which can cause the LED chip to shift or even debond after long-term use; or the FPC is not conducive to flexible changes in process conditions.

[0004] The applicant has previously disclosed a flexible filament (e.g., some embodiments of Chinese Patent Publication No. CN106468405A). This flexible filament structure, devoid of a substrate, offers a flexible, wavelength-converting fluorescent package, replacing the traditional structure that requires mounting the chip on a substrate before applying phosphor and encapsulating it. However, some filament structures pose challenges to the stability of the metal bonding wires between the chips during bending. When the chips are densely arranged within the filament, connecting adjacent LED chips via metal bonding can easily lead to excessive stress concentration in specific locations within the filament during bending, potentially damaging or even breaking the metal bonding wires connecting the LED chips. Therefore, some embodiments still require further improvement in quality.

[0005] Existing flexible filament products require different LED filament shapes depending on the bulb type, resulting in varying filament lengths. For the same filament, using the same number of LED chips, longer filament length increases the spacing between adjacent LED chips. When the filament is lit, the light spots (or graininess) observed by the naked eye become more noticeable, significantly impacting user comfort.

[0006] In the existing technology, most LED lamps use a combination of blue LED chips and yellow phosphors to emit white light. However, the light in the red region of the LED lamp's emission spectrum is weak, and the color rendering index is low, making it difficult to achieve a low color temperature. To improve the color rendering index, a certain amount of green phosphor and red phosphor are generally added. However, the relative conversion rate of red phosphor is low, which usually leads to a decrease in the overall luminous flux of the LED lamp, that is, a decrease in light efficiency. Secondly, the red, green, and blue cone cells in the human eye have different sensitivities. If red light is lacking, the green light and blue light will form a cyan image in the human eye, reducing the color gamut of color reproduction. This not only makes the lighting scene dull and boring, but also affects the quality of the lighting environment. In addition, using lighting with high color rendering can improve people's perception of space, while low color rendering affects the ability to distinguish objects and accurately perceive the surrounding environment.

[0007] Existing LED filaments typically only have a phosphor glue coating applied to their outer surface. However, since different color temperatures of phosphor glue exhibit different colors after drying, when multiple LED filaments with different color temperatures are installed, a chaotic display of colors appears, making the LED lamp less aesthetically pleasing as a decorative light. Some designs incorporate graphene glue layers above and below the substrate, modulating the graphene to different colors to mitigate the visual impact of the varying colors of the phosphor glue layers. However, graphene production is expensive and can pollute the environment.

[0008] The LED chip has a first light-emitting surface and a second light-emitting surface, which are opposite to each other. The light emitted from the first light-emitting surface (front) is directed toward the top layer, and the light emitted from the second light-emitting surface (back) is directed toward the supporting layer. Generally, the back of a flip-chip or back-plated front-mounted LED chip is basically opaque, and the brightness difference between the front and back of the LED chip is large. If the above-mentioned LED chip is used in an LED filament, the luminous flux in some directions will be less after the LED filament is wound, and the light output of the LED bulb will be uneven.

[0009] Furthermore, LED filaments are typically incorporated into LED bulbs. To enhance their aesthetics and provide a more uniform and wide-ranging illumination, they are often bent into various curves. However, the LED chips within the filaments are relatively rigid, making them difficult to bend into the desired shape. Furthermore, the filaments are prone to cracking due to stress concentration during bending.

[0010] In addition, LED filaments are generally arranged in a straight line around the core column, and the LED filaments emit very little light near the two ends. When one end of multiple LED filaments is installed close to each other near the top of the light output of the bulb, a dark area will be formed in the light output direction of the central axis of the bulb, resulting in uneven spatial distribution of the output light, uneven illumination distribution, and problems such as the "darkness under the lamp" phenomenon.

[0011] Currently, LED filament lamps typically use a driver power supply to convert AC power into DC power before driving the lamp to emit light. However, the ripple generated during the AC-to-DC rectification process can cause flickering in the LED filament. To reduce or even eliminate the flickering produced by LED filaments, an electrolytic capacitor is typically added to the driver power supply to remove the ripple. However, the heat generated by the heating elements in the driver power supply can significantly impact the lifespan of the electrolytic capacitor.

[0012] When a lighting device includes multiple LED components, the multiple LED components need to be driven using different currents. If multiple drivers are used, the circuit complexity and cost will inevitably increase. Therefore, a shunt circuit is required to distribute the current among the multiple LED components.

[0013] Finally, when the semiconductor dispensing device of the prior art performs dispensing operations on the flexible filament semiconductor, there are dispensing anomalies, which lead to subsequent failure of normal wire bonding or problems in the bonding between the LED chip and the base film.

[0014] In summary, in view of the deficiencies and defects of the existing technology, how to improve the above problems is a technical problem that urgently needs to be solved by those skilled in the art.

[0015] Summary of the Invention

[0016] It is particularly noted that the present disclosure may actually include one or more technical solutions that are currently claimed for protection or have not yet been claimed for protection, and in order to avoid confusion due to unnecessary distinctions between these technical solutions during the process of writing the specification, the possible multiple technical solutions in this article may be collectively referred to as "this application".

[0017] This summary describes a number of embodiments of the present application. However, the term "present application" is used only to describe certain embodiments disclosed in this specification (whether or not included in the claims), and is not a complete description of all possible embodiments. Certain embodiments of the various features or aspects described below as "present application" may be combined in various ways to form an LED bulb or a portion thereof.

[0018] The present application discloses an LED bulb lamp, which includes a lamp housing and a lamp base connected to the lamp housing. At least one cantilever, a stem and an LED filament are provided in the lamp housing. The stem includes a vertical rod. Each cantilever includes a first end and a second end opposite to each other. The first end of the cantilever is connected to the vertical rod, and the second end of the cantilever is connected to the LED filament. The LED bulb lamp is located in a spatial coordinate system (X, Y, Z), wherein the Z axis is parallel to the stem. On the XY plane, the central angle corresponding to the arc at which at least two bending points of the LED filament are located ranges from 170° to 220°.

[0019] Preferably, each cantilever has an intersection with the LED filament, and on the XY plane, at least two intersections are located on a circle with the core as the center.

[0020] Preferably, the LED filament includes an LED segment and a conductor segment connecting two adjacent LED segments, and in the Z-axis direction, the height of the vertical rod is greater than the height of the conductor segment.

[0021] Preferably, the LED filament also includes an electrode connecting the LED segment, and the LED segment includes a first segment and a second segment. The first segment is formed by the electrode extending toward the top of the lamp housing to the bending point, and the second segment is formed by extending from the bending point toward the lamp head to the conductor segment. The first segment and the second segment have relative first and second distances from the lamp housing, and the first distance is smaller than the second distance.

[0022] Preferably, the LED filament further includes a light conversion layer, which includes a top layer and a base layer. The LED segment and the conductor segment are placed on the base layer, and the top layer covers the LED segment and the conductor segment and part of the electrode. In the first distance direction, the base layer of the LED filament is close to the lamp housing, and the top layer of the LED filament is away from the lamp housing.

[0023] Preferably, a bonding adhesive is provided between the base layer and the LED chip, and at least 80% of the bottom surface of each chip unit attached to the base layer is covered with the bonding adhesive.

[0024] The present application also discloses an LED bulb lamp, which includes a lamp housing and a lamp head connected to the lamp housing. A core column and an LED filament are provided in the lamp housing. The lamp housing is divided into an upper part and a lower part by a plane A. The lamp housing has a maximum width at plane A. The core column and the plane have an intersection. The lamp housing has a relative lamp housing top and lamp housing bottom. The lamp housing bottom is close to the lamp head. The length of the filament between the lamp housing top and plane A is less than the length of the filament between plane A and the lamp housing bottom.

[0025] Preferably, in the height direction of the LED bulb, the distance from the highest point of the LED filament to the plane A is smaller than the distance from the lowest point of the LED filament to the plane A in the height direction of the LED bulb.

[0026] Preferably, the lamp housing is filled with gas containing oxygen.

[0027] Preferably, the LED bulb is located in a spatial coordinate system (X, Y, Z), wherein the Z axis is parallel to the core column, and the LED bulb further comprises at least one cantilever connected to the core column, each cantilever having an intersection with the LED filament, and on the XY plane, at least two intersections are located on a circle with the core column as the center.

[0028] Preferably, the LED filament includes an LED segment, a conductor segment connecting two adjacent LED segments, and an electrode connected to the LED segment. A line connecting at least one intersection point and a bending point of the conductor segment forms a straight line La. The intersection point on the straight line La forms a straight line Lb with the electrode of the filament. The angle α between the straight line La and the straight line Lb is in the range of 0°<α<90°.

[0029] The present application has the following or any combination of technical effects through the above technical solutions: (1) by filling the lamp housing with a combination of nitrogen and oxygen, the service life of the base layer can be effectively improved due to the interaction between oxygen and the radicals in the base layer; (2) by designing the relationship between the diameter of the lamp head, the maximum diameter of the lamp housing and the maximum width of the LED filament in the Y-axis direction on the YZ plane or the maximum width in the X-axis direction on the XZ plane, the heat dissipation effect of the bulb lamp can be effectively improved; (3) the thickness of the base layer is less than the thickness of the top layer. Since the thermal conductivity of the top layer is greater than the thermal conductivity of the base layer, the distance for the heat generated by the LED chip to be conducted to the outer surface of the base layer is relatively short, so that heat is not easily accumulated, and the heat dissipation effect of the LED filament is good; (4) the supporting layer includes a transparent layer and a base layer. The transparent layer plays a supporting role for a part of the base layer, thereby enhancing the strength of the base layer and facilitating die bonding. The part of the base layer not covered by the transparent layer allows a part of the heat generated by the LED chip to be directly dissipated through the base layer; (5) The transparent layer includes a first transparent layer and a second transparent layer. When the LED filament is bent, the electrode is prone to separation from the light conversion layer or the part where the light conversion layer contacts the electrode is prone to cracks. The first transparent layer and the second transparent layer can structurally reinforce the part where the light conversion layer contacts the electrode to prevent cracks from occurring in the part where the light conversion layer contacts the electrode; (6) The conductor includes a covering part and an exposed part. When the LED filament is bent, the exposed part will be slightly deformed due to the force. The bending area is small and the degree of deformation is small, which is conducive to maintaining the bending shape of the LED filament. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG1A is a schematic structural diagram of another embodiment of an LED filament of the present application;

[0031] FIG1B is a schematic structural diagram of another embodiment of an LED filament of the present application;

[0032] FIG1C is a schematic structural diagram of another embodiment of an LED filament of the present application;

[0033] 1D to 1G are schematic structural diagrams showing multiple embodiments of the LED filament of the present application;

[0034] FIG1H is a top view of an embodiment of an LED filament of the present application with the top layer removed;

[0035] FIG1I is a schematic structural diagram of another embodiment of an LED filament of the present application;

[0036] FIG1J is a schematic structural diagram of another embodiment of an LED filament of the present application;

[0037] FIG1K is a schematic diagram of the structure of LED chip bonding wires according to an embodiment;

[0038] FIG1L is a top view of an embodiment of the present application showing an LED filament in an unbent state with the top layer removed;

[0039] FIG1M is a top view of an embodiment of the present application showing an LED filament in an unbent state with the top layer removed;

[0040] FIG1N is a schematic diagram of the structure of an LED filament in an unbent state in an embodiment of the present application;

[0041] FIG10 is a schematic diagram of the structure of an LED filament in an unbent state in some embodiments of the present application;

[0042] FIG1P is a schematic diagram of a partial structure of an LED filament in one embodiment of the present application;

[0043] FIG1Q is a schematic cross-sectional view of FIG1P ;

[0044] FIG1R is a schematic diagram of a partial structure of an LED filament in one embodiment of the present application;

[0045] FIG1S is a schematic diagram of a partial structure of an LED filament in one embodiment of the present application;

[0046] [Corrected 18.11.2022 according to Rule 91] FIG1T is a schematic diagram of the structure of an LED filament in an embodiment of the present application;

[0047] [Corrected 18.11.2022 according to Rule 91] FIG1U is a schematic diagram of the structure of an LED filament in some embodiments of the present application;

[0047] [Corrected 18.11.2022 according to Rule 91] FIG. 1V is a schematic diagram of the structure of an LED filament in some embodiments of the present application;

[0048] [Corrected 18.11.2022 according to Rule 91] FIG1W is a schematic diagram of the structure of an LED filament in some embodiments of the present application;

[0049] FIG2A is a schematic structural diagram of an embodiment of an LED filament of the present application;

[0050] FIG2B is a bottom view of FIG2A ;

[0051] FIG2C is a partial cross-sectional schematic diagram of the AA position in FIG2A;

[0052] 3A to 3E are schematic diagrams of a first embodiment of a method for manufacturing an LED filament according to the present application;

[0053] 4A to 4D respectively show a schematic diagram, a side view, another side view, and a top view of an LED bulb according to an embodiment of the present application;

[0054] FIG5 is a schematic diagram of an LED bulb according to an embodiment of the present application;

[0055] FIG6A is a schematic diagram of a lamp holder according to an embodiment of the present application;

[0056] FIG6B is a schematic diagram of the AA section in FIG6A ;

[0057] FIG7A is a schematic diagram of a lamp holder according to an embodiment of the present application;

[0058] FIG7B is a schematic diagram of an embodiment of the BB section in FIG7A ;

[0059] FIG7C is a schematic diagram of an embodiment of the cross section BB in FIG7A ;

[0060] 8A to 8D respectively show a schematic diagram, a side view, another side view, and a top view of an LED bulb according to an embodiment of the present application;

[0061] 9A to 9D respectively show a schematic diagram, a side view, another side view, and a top view of an LED bulb according to an embodiment of the present application;

[0062] FIG10A is a schematic diagram of an LED filament when it is not bent according to an embodiment;

[0063] FIG10B is a schematic diagram of an LED bulb lamp using the LED filament shown in FIG10A;

[0064] FIG11A is a schematic diagram of an LED bulb according to an embodiment;

[0065] FIG11B is an enlarged schematic diagram of portion A in FIG11A ;

[0066] FIG12 is a schematic diagram showing the light spectrum of an LED bulb according to an embodiment of the present application;

[0067] FIG13 is a schematic diagram showing the light spectrum of an LED bulb lamp according to an embodiment of the present application;

[0068] FIG14 is a schematic diagram showing a light spectrum of an LED bulb lamp according to an embodiment of the present application;

[0069] FIG15 is a schematic diagram of light transmission of the LED bulb of the present application;

[0070] FIG16 is a schematic diagram of the C0 / 180 plane and the C90 / 270 plane of the LED bulb of the present application;

[0071] FIG17 is a light distribution curve diagram of an LED bulb according to an embodiment;

[0072] FIG18 is a light distribution curve diagram of an LED bulb according to an embodiment;

[0073] FIG19 is a light distribution curve diagram of an LED bulb according to an embodiment;

[0074] FIG20 is a light distribution curve diagram of an LED bulb according to an embodiment;

[0075] 21 is a circuit diagram of a first constant current circuit according to an embodiment of the present invention;

[0076] 22 is a circuit diagram of a second constant current circuit according to an embodiment of the present invention;

[0077] 23 is a circuit diagram of a third constant current circuit according to an embodiment of the present invention;

[0078] FIG24 is a circuit block diagram of an LED lamp according to an embodiment of the present application;

[0079] FIG25A is a schematic diagram of the circuit structure of an LED lamp according to an embodiment of the present application;

[0080] FIG25B is a schematic diagram of the circuit structure of an LED lamp according to another embodiment of the present application;

[0081] FIG25C is a schematic diagram of the circuit structure of an LED lamp according to another embodiment of the present application;

[0082] In the picture:

[0083] R1 to R4 are the first to fourth resistors respectively; M1 is the main switching element, Q1 is the auxiliary switching element, and switching devices such as field effect tubes and triodes can be used; D5 is a light-emitting diode or a light-emitting diode group; PTC is a PTC resistor; V2 is a voltage source. DETAILED DESCRIPTION

[0084] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0085] As shown in FIG. 1A to FIG. 1M , FIG. 2A to FIG. 2C and FIG. 3A to FIG. 3E , the LED filament has a light conversion layer 220 / 420 , an LED chip unit 202 / 204 (or an LED segment 402 / 404 ) and electrodes (or conductive electrodes) 210 , 212 / 410 , 412 . The light conversion layer 220 / 420 encapsulates the LED chip units 202 / 204 (or LED segments 402 / 404) and portions of the electrodes (or conductive electrodes) 210, 212 / 410, 412. Portions of the electrodes (or conductive electrodes) 210, 212 / 410, 412 are exposed outside the light conversion layer 220 / 420. Adjacent LED chip units 202, 204 (or LED segments 402, 404) are electrically connected to each other, as are the LED chip units 202 / 204 (or LED segments 402 / 404) and the electrodes (or conductive electrodes) 210, 212 / 410, 412. The LED filament includes at least two LED chips 442, with adjacent LED chips 442 electrically connected to each other. The LED chip units 202 / 204 (or LED segments 402 / 404) include at least one LED chip 442. The light conversion layer 420 includes a top layer 420a and a carrier layer. The top layer 420a and the carrier layer can each be a layered structure of at least one layer. The layered structure can be selected from: a phosphor glue with high plasticity (relative to the phosphor film), a phosphor film with low plasticity or a transparent layer, or any combination of the three. The phosphor glue / phosphor film contains the following ingredients: silicone-modified polyimide and / or glue. The phosphor glue / phosphor film can also include phosphor, inorganic oxide nanoparticles (or heat dissipation particles). The transparent layer 420c can be composed of a light-transmitting resin (such as silicone, polyimide) or a combination thereof. The glue can be, but is not limited to, silicone. In one embodiment, the top layer 420a and the carrier layer are made of the same material. In one embodiment, the carrier layer includes a base layer 420b. In the height direction of the LED filament, the height of the top layer 420a is greater than the height of the base layer 420b. The base layer 420b includes relative upper and lower surfaces, and the top layer 420a includes relative upper and lower surfaces, and the upper surface of the base layer 420b contacts a portion of the lower surface of the top layer 420a; the LED chip 442 includes relative upper and lower surfaces, and the upper surface of the LED chip 442 is close to the upper surface of the top layer 420b relative to the lower surface of the LED chip 442, and the distance from the lower surface of the LED chip 442 to the lower surface of the base layer 420b is smaller than the distance from the lower surface of the LED chip 442 to the upper surface of the top layer 420a. Since the thermal conductivity of the top layer 420a is greater than the thermal conductivity of the base layer 420b, the distance for the heat generated by the LED chip 442 to be conducted to the outer surface of the base layer 420b is relatively short, so that heat is not easily accumulated, and the heat dissipation effect of the LED filament is good.In one embodiment, if the LED filament is supplied with no more than 8W of electrical energy, when the LED filament is illuminated, it emits a luminous flux of at least 4 lm per millimeter of LED filament length (or per millimeter of filament body length or per millimeter of top layer 420a length). In one embodiment, at least two LED chips 442 are included per millimeter of LED filament length (or per millimeter of filament body length or per millimeter of top layer 420a length), and the junction temperature of the LED chips 442 is no greater than the junction temperature of the LED chips 442 after 15,000 hours of illumination in an ambient temperature of 25°C. Alternatively, if the LED filament is supplied with no more than 8W of electrical energy, when the LED filament is illuminated, it emits a luminous flux of at least 4 lm per cubic millimeter of LED filament volume (or per cubic millimeter of filament body volume or per cubic millimeter of top layer 420a volume). In one embodiment, at least two LED chips are included per cubic millimeter of the LED filament volume (or per cubic millimeter of the filament body volume or per cubic millimeter of the top layer 420a volume), and the junction temperature of the LED chip 442 in an ambient environment of 25°C is no greater than the junction temperature of the LED chip 442 after the LED filament has been lit for 15,000 hours. In some embodiments, the lifespan of the LED chip 442 can be related to the thermal equilibrium temperature (e.g., the junction temperature of the LED chip 442). The relationship between the lifespan of the LED chip 442 and the junction temperature varies depending on the manufacturer of the LED chip 442. In the LED filament, heat from the LED chip 442 is transferred to the ambient environment via thermal conduction, maintaining the temperature at or below a specific temperature (e.g., maintaining the junction temperature of the LED chip at or below the junction temperature of the LED chip over its rated lifespan of 15,000 hours in an ambient environment of 25°C).

[0086] In most applications, filament lamps are no longer simply for lighting purposes; they have become a decorative element. Specifically, when the filament is unlit, consumers focus on the filament's shape and color (including the filament's color (or the color of the filament body) and the color of the bulb itself). When the filament is lit, consumers prioritize color temperature and illumination compliance. The filament body mentioned above does not include the portion of the electrode exposed from the light conversion layer 420. In one embodiment, when the LED filament is unlit, the surface of the filament appears white, gray, black, blue, green, or purple. In some embodiments, the surface of the filament may also be the surface of the light conversion layer 420. When lit, the filament emits light of a different color than when unlit, allowing bulbs with this filament to be used in different scenarios and achieve diverse decorative effects. In some embodiments, the LED filament includes a coating, and the coating may be white, gray, black, blue, green, or purple. The coating covers at least a portion of the surface of the light conversion layer 420, and preferably covers the entire surface of the light conversion layer 420. For example, if a red coating is used to cover the surface of the light conversion layer 420, the surface of the LED filament appears red when the LED filament is not lit, but when the LED filament is lit, the LED filament emits white light. Of course, after the LED filament is lit, it can emit light of the same color as when the LED filament is not lit. For example, if a white coating is used to cover the surface of the light conversion layer 420, the surface of the LED filament appears white when the LED filament is not lit, and when the LED filament is lit, the light emitted by the LED filament is also white. The white coating can be aluminum oxide. In some embodiments, the surface of the top layer 420a and / or the carrier layer is covered with a thin film, and the color of the film is black, gray, red, etc. Generally, all substances have a certain degree of light absorption. Preferably, a film with high light transmittance is used, for example, a film with a light transmittance of at least greater than 80, which can prevent the luminous flux from decreasing after the LED filament is lit. In some embodiments, the film is thinner than the top layer 420a, so that heat generated by the LED chip 442 is less likely to accumulate in the film, thereby balancing the appearance and heat dissipation requirements of the LED filament. The film may or may not contain phosphor. When the film contains phosphor, the phosphor content of the film is less than the phosphor concentration of the top layer 420a or the carrier layer. If the top layer 420a or the carrier layer is multi-layered, the phosphor content of the film is at least less than the phosphor content of one of the layers. Due to the presence of the film, the thickness of the LED filament increases, and the heat conduction path of the LED filament becomes longer. Increasing the phosphor content in the film to improve the heat dissipation performance of the LED filament increases its hardness due to the increased phosphor content, making the LED filament less flexible and increasing the probability of cracking when the LED filament is bent. Therefore, by adding a certain amount of phosphor to the film, the color of the LED filament when it is not lit can be changed while balancing the heat dissipation performance and flexibility of the LED filament.In some embodiments, after the top layer 420a and / or the base layer are coated with a thin film, the main body of the filament appears grayish black (close to the original color of a tungsten filament) when the filament is unlit, and the light emitted by the LED filament appears white when the filament is lit. In some embodiments, the color of the light conversion layer, the main body of the filament, etc. when the filament is unlit, or the color of the light emitted by the LED filament when it is lit, includes a primary color or a color blended from at least two primary colors, such as the three primary colors of light (RGB).

[0087] As shown in FIG1W , the aforementioned coating or film is a layer 480 disposed on the outer surface of the light conversion layer 420. In some embodiments, the hardness of the layer 480 is less than that of the light conversion layer 420 to prevent the layer 480 from being too hard and thus affecting the normal bending of the filament. In some embodiments, the hardness of the layer 480 can be greater than that of the light conversion layer 420 to provide further support for the entire filament. Regardless of the hardness of the layer 480, the provision of the layer 480 can improve the overall support of the filament.

[0088] The bulb of a filament lamp is filled with gas, and the refractive indices of the light conversion layer 420, the layered body 480, and the gas filling the bulb decrease in sequence. Compared to a lamp without a layered body, the significant difference in refractive index between the light conversion layer and the gas filling can result in greater light loss. However, the aforementioned arrangement of the layered body 480 in this embodiment minimizes light loss along the light output path of the LED chip 442.

[0089] The layered body 480 can be made of silicone or a material primarily composed of silicone. When silicone is used directly, the color of the silicone itself can be used to make the layered body 480 appear white, thereby giving the filament a white appearance. By adding a colorant to the silicone, the layered body 480 can be made to exhibit different colors as described above. Furthermore, a photoreactive substance can be added to the layered body 480 so that after the LED chip emits light, it undergoes a first light conversion through the light conversion layer 420, and then a second light conversion through the photoreactive substance within the layered body 480. This allows the LED filament to have a first color when unlit and a second color different from the first color when lit, with the first and second colors having a primary color difference.

[0090] In one embodiment, the light conversion layer 420 includes a top layer 420a and a carrier layer. The top layer 420a and the carrier layer can each comprise at least one layer. The top surface of the top layer 420a and the bottom surface of the carrier layer have different colors. Because the LED filament exhibits two different colors when unlit, it can be applied to multi-color scenarios.

[0091] In some embodiments, when the LED chips 442 are arranged in only one row along the width of the LED filament (as shown in FIG. 2B , where the LED chips 442 (i.e., in FIG. 2B ) are arranged in the same direction), the LED filament has a bendable section and a non-bendable section along its length, and the total length of the bendable section is less than the total length of the non-bendable section, thereby providing better support for the entire LED filament. The non-bendable section is the total length of the LED filament along its length that includes the LED chips 442 or the electrodes 210 , 212 / 410 , 412 , while the bendable section is the section that includes only the light conversion layer 220 / 420 and / or the conductive wires (the conductive wires herein refer to the conductive wires connecting adjacent LED chips or the conductive wires connecting the LED chips to the electrodes). In other words, the section along the length of the LED filament that is not provided with the LED chips 442 or the electrodes 210 , 212 / 410 , 412 constitutes the bendable section.

[0092] In some embodiments, in the length direction of the LED filament, the total length of the bendable section accounts for at least 30% of the total length of the LED filament to ensure the bendability of the filament.

[0093] In some embodiments, along the length direction of the LED filament, the total length of the bendable section accounts for at least 30% and no more than 50% of the total length of the LED filament, thereby making the LED filament both bendable and supportive.

[0094] In some embodiments, when the LED chips 442 are arranged in two rows along the width of the LED filament and the two rows of LED chips 442 are connected in parallel (as shown in FIG. 1L ), the LED filament also has a bendable section and a non-bendable section along its length, with the total length of the bendable sections being less than the total length of the non-bendable sections. This allows the entire LED filament to have better support and bendability. The non-bendable section is the total length of the LED filament along its length that includes the LED chips 442 or the electrodes 210, 212 / 410, 412, while the bendable section is comprised solely of the light conversion layer 220 / 420 and / or conductive wires (the conductive wires herein refer to conductive wires connecting adjacent LED chips or conductive wires connecting an LED chip to an electrode). Specifically, the bendable section is comprised of the portion of the LED filament along its length that is not provided with the LED chips 442 or the electrodes 210, 212 / 410, 412.

[0095] In some embodiments, the total length of the bendable segments accounts for at least 0.001% and no more than 20% of the total length of the LED filament. In some embodiments, the portion of the LED filament where the LED chips are located (i.e., the area between the leftmost and rightmost LED chips in FIG. 1L ) may not have a bendable segment. However, due to the staggered arrangement of adjacent LED chips, the filament still exhibits a certain degree of bendability.

[0096] In some embodiments, when the LED chips 442 are arranged in two rows along the width of the LED filament, and the two rows of LED chips 442 are connected in series (as shown in FIG. 1M ), the LED filament has a bendable section and a non-bendable section along its length, and the total length of the bendable section is less than the total length of the non-bendable section, thereby providing better support for the entire LED filament. The non-bendable section is the total length of the LED filament along its length that includes the LED chips 442 or the electrodes 210, 212 / 410, 412, while the bendable section is the section that includes only the light conversion layer 220 / 420 and / or the conductive wires (the conductive wires herein refer to the conductive wires connecting adjacent LED chips or the conductive wires connecting the LED chips to the electrodes). In other words, the section along the length of the LED filament that is not provided with the LED chips 442 or the electrodes 210, 212 / 410, 412 constitutes the bendable section.

[0097] In some embodiments, along the length direction of the LED filament, the total length of the bendable section accounts for at least 0.001% and no more than 30% of the total length of the LED filament, thereby making the LED filament both bendable and supportive.

[0098] In some embodiments, regardless of whether one or two rows of LED chips are arranged on the LED filament, more than 0.5 LED chips are arranged per unit length (per millimeter) so that a reasonable spacing can be set between the LED chips to meet the requirements of light uniformity and prevent serious thermal effects between the LED chips.

[0099] Figure 1A is a schematic diagram of the structure of an embodiment of an LED filament according to the present application. The LED filament 400 comprises a light conversion layer 420, LED segments 402 / 404, and electrodes 410 / 412. LED segments 402 / 404 include at least one LED chip 442. Adjacent LED chips within the LED filament, as well as the LED chips and electrodes 410 / 412, are electrically connected to each other. This electrical connection can be achieved, for example, via a circuit film or, as described later, first conductive wires 440 (see Figure 1B). The light conversion layer 420 comprises a top layer 420a and a carrier layer. The carrier layer comprises a base layer 420b and a transparent layer 420c. The base layer 420b is located between the top layer 420a and the transparent layer 420c (at least on a cross section of the LED filament 400). In one embodiment, the base layer 420b includes relative upper and lower surfaces, the upper surface of the base layer 420b contacts a portion of the top layer 420a, and the lower surface of the base layer 420b contacts the transparent layer 420c. In some embodiments, the lower surface of a portion of the base layer 420b contacts the transparent layer 420c, and the transparent layer 420c supports a portion of the base layer 420b, thereby enhancing the strength of the base layer 420b and facilitating die bonding. The portion of the base layer 420b that is not covered by the transparent layer 420c allows the heat generated by a portion of the LED chip 442 to be directly dissipated through the base layer 420b. In this embodiment, the total length of the base layer 420b is the same as the total length of the top layer 420a. In one embodiment, the total length of the transparent layer 420c is 5-100% of the total length of the base layer 420b. In one embodiment, the length of the transparent layer 420c is less than the length of the base layer 420b, and the total length of the transparent layer 420c is 10-80% of the total length of the base layer 420b. In one embodiment, the total length of the transparent layer 420c is 10-50% of the total length of the base layer 420b. When the LED filament is thin (for example, the width of the LED filament is ≤120μm), the heat dissipation area of ​​the LED chip is relatively reduced. Since the transparent layer is located below the base layer, on the one hand, deformation of the base layer caused by heat can be reduced; on the other hand, it can help support the LED chip and facilitate die bonding. In one embodiment, transparent layer 420c includes a first transparent layer 420c1 and a second transparent layer 420c2. Both first transparent layer 420c1 and second transparent layer 420c2 extend along the length of the LED filament. First transparent layer 420c1 extends from one end of base layer 420b, and second transparent layer 420c2 extends from the other end of base layer 420b. The extension direction of first transparent layer 420c1 is opposite to the extension direction of second transparent layer 420c2. In one embodiment, light conversion layer 420 has a first end and a second end opposite the first end. In one embodiment, LED chip 442 is located between the first and second ends. If the LED chip closest to the first end is denoted as LED chip n1, then the LED chips from the first end to the second end are LED chips n2, n3, ..., n. m, m is an integer and m≤800. In some embodiments, 50≤m≤300. The length of the first transparent layer 420c1 and / or the second transparent layer 420c2 along the length of the LED filament is at least greater than the distance from the first end to the LED chip n2. A gap exists between the first transparent layer 420c1 and the second transparent layer 420c2. Along the length of the LED filament, the distance between the first transparent layer 420c1 and the second transparent layer 420c2 is greater than the length of the first transparent layer 420c1 and / or the second transparent layer 420c2. When the LED filament is bent, the electrodes near the light conversion layer are prone to separation, or cracks may form in the portion of the light conversion layer contacting the electrodes. The first transparent layer 420c1 and the second transparent layer 420c2 can provide structural reinforcement in the portion of the light conversion layer contacting the electrodes, preventing cracks in the portion of the light conversion layer 420 contacting the electrodes 410 / 412.

[0100] FIG1B is a schematic diagram of another embodiment of an LED filament according to the present invention. As shown in FIG1B , LED filament 400 comprises a light conversion layer 420; LED segments 402 and 404; electrodes 410 and 412; and a conductor segment 430 for electrically connecting adjacent LED segments 402 and 404. LED segments 402 and 404 include at least two LED chips 442, which are electrically connected to each other via a first conductive wire 440. In this embodiment, conductive segment 430 includes a conductor 430a that connects LED segments 402 and 404. The shortest distance between two LED chips 442 within adjacent LED segments 402 and 404 is greater than the distance between adjacent LED chips within each LED segment 402 and 404, and the length of first conductive wire 440 is shorter than the length of conductor 430a. This ensures that stress generated when bending between the two LED segments prevents the conductive segment from breaking. The light conversion layer 420 is coated on at least two sides of the LED chip 442 and the electrodes 410 and 412. The light conversion layer 420 exposes portions of the electrodes 410 and 412. The light conversion layer 420 comprises a top layer 420a and a carrier layer, serving as the upper and lower layers of the LED filament, respectively. In this embodiment, the carrier layer comprises a base layer 420b, which includes an upper surface and a lower surface opposite the upper surface. The upper surface of the base layer 420b is adjacent to the top layer 420a, with the LED segments 402 / 404 and portions of the electrodes 410 / 412 positioned on the upper surface of the base layer 420b. Alternatively, at least one side of the LED segments 402 / 404 is in direct or indirect contact with the upper surface of the base layer 420b.

[0101] As shown in FIG1C , in this embodiment, a conductor segment 430 is also located between two adjacent LED segments 402 and 404, and the multiple LED chips 442 within each LED segment 402 and 404 are electrically connected to each other via a first conductive wire 440. However, the conductor 430a within the conductor segment 430 in FIG1C is not in the form of a wire, but rather in the form of a sheet or film. In some embodiments, the conductor 430a can be made of copper foil, gold foil, or other electrically conductive materials. In this embodiment, the conductor 430a is attached to the surface of the base layer 420b and adjacent to the top layer 420a, that is, located between the base layer 420b and the top layer 420a. Furthermore, the conductor segment 430 is electrically connected to the LED segments 402 and 404 via a second conductive wire 450. Specifically, the two LED chips 442 within the adjacent LED segments 402 and 404, respectively, and the shortest distance from the conductor segment 430, are electrically connected to the conductor 430a within the conductor segment 430 via the second conductive wire 450. The length of the conductor segment 430 is greater than the distance between two adjacent LED chips 442 in the LED segments 402 and 404, and the length of the first wire 440 is less than the length of the conductor 430a. With this design, since the conductor segment has a relatively long length, it can be ensured that the conductor segment has good bendability. Assuming that the maximum thickness of the LED chip 442 in the radial direction of the LED filament is H, the thickness of the electrode 410 / 412 and the conductor 430a in the radial direction of the LED filament is 0.5H to 1.4H, preferably 0.5H to 0.7H. There is a height difference between the LED chip and the electrode, and between the LED chip and the conductor, so that the wire bonding process can be implemented, while ensuring the quality of the wire bonding process (that is, having good strength), thereby improving the stability of the product.

[0102] As shown in FIG1D , an LED filament 400 comprises a light conversion layer 420; LED segments 402 and 404; electrodes 410 and 412; and a conductor segment 430 for electrically connecting adjacent LED segments 402 and 404. The LED segments 402 and 404 include at least one LED chip 442. The conductor segment 430 is electrically connected to the LED segments 402 and 404 via a second conductive wire 450. Specifically, the two LED chips 442 located within adjacent LED segments 402 and 404 and closest to the conductor segment 430 are electrically connected to a conductor 430a within the conductor segment 430 via the second conductive wire 450. The LED chips 442 are electrically connected to each other via a first conductive wire 440. The conductor segment 430 includes a conductor 430a that connects the LED segments 402 and 404. The conductor 430a may be a conductive metal sheet or strip, such as a copper or iron sheet. The shortest distance between two LED chips 442 within adjacent LED segments 402 and 404 is greater than the distance between two adjacent LED chips within each LED segment 402 or 404. The length of the first conductive wire 440 is shorter than the length of the conductor 430a. This ensures that when the two LED segments are bent, the conductor segment bears a larger force area, preventing the generated stress from causing the conductor segment to break. The light conversion layer 420 covers at least two sides of the LED chips 442 and the electrodes 410 and 412. The light conversion layer 420 exposes a portion of the electrodes 410 and 412. The light conversion layer 420 includes a top layer 420a and a supporting layer. The supporting layer includes a base layer 420b and a transparent layer 420c. The base layer 420b is located between the top layer 420a and the transparent layer 420c. The base layer 420b and the top layer 420a cover at least two sides of the LED chip 442. The thermal conductivity of the transparent layer 420c is greater than the thermal conductivity of the base layer 420b. The thickness of the base layer 420b in the radial direction of the LED filament is less than or equal to the thickness of the conductor 430a in the radial direction of the LED filament. When the LED filament is thinner (for example, the width of the LED filament is ≤120μm), the heat dissipation area of ​​the LED chip is relatively reduced. By adopting the transparent layer, on the one hand, the deformation of the base layer caused by heat can be reduced. On the other hand, it can assist in supporting the LED chip, which is beneficial to die bonding. The transparent layer 420c can be, for example, a hard substrate such as an alumina ceramic plate or a sapphire substrate, or a soft substrate with a high thermal conductivity (for example, a thermal conductivity ≥ 2.0 (W / (m·K)). The translucent alumina ceramic plate or transparent sapphire substrate facilitates the transmission of light emitted from the LED chip toward the transparent layer, thereby achieving full-circle light for the LED filament. In this embodiment, the top layer 420a, the base layer 420b, and the transparent layer 420c wrap the conductor 430a, which, on the one hand, reduces the impact of the external environment on the conductor, and on the other hand, increases the bearing capacity of the conductor during electrical connection, thereby improving the electrical connection stability when the conductor is bent.In some embodiments, the thickness of the base layer 420b along the height of the LED filament is less than or equal to the thickness of the conductor 430a along the height of the LED filament. This shortens the heat conduction path from the LED chip to the transparent layer, improving heat dissipation from the LED filament. In other embodiments, the thickness of the transparent layer 420c along the height of the LED filament is greater than the thickness of the base layer 420b along the height of the LED filament. This shortens the heat conduction path from the LED chip to the transparent layer, improving heat dissipation from the LED filament. In some implementations, the absolute value of the height difference between the LED chip 442 and the conductor 430a along the height of the LED filament is greater than the height of the LED chip 442 along the height of the LED filament. When the LED filament bends, the second conductor is stretched and deformed less, making it less likely to break. In some embodiments, the base layer 420b contacts at least one side of the LED chip 442 and one side of the conductor segment 430. In this embodiment, the LED chip 442 and the conductor 430a are located on different sides of the base layer 420b.

[0103] Referring to Figures 1E to 1G , in some embodiments, conductor 430a includes a covering portion 430b and an exposed portion 430c. The length of the exposed portion 430c in the axial direction of the LED filament is less than the distance between adjacent LED chips within any LED segment 402 / 404. When the LED filament is bent, the exposed portion 430c is slightly deformed by the force applied, resulting in a small bending area and minimal deformation, which helps maintain the bent shape of the LED filament. As shown in Figure 1E , the exposed portion 430c includes a first exposed portion 430c1 and a second exposed portion 430c2. The portion of the top layer 420a that exposes the conductor 430a is the first exposed portion 430c1, and the portion of the transparent layer 420c that exposes the conductor 430a is the second exposed portion 430c2. The length of the first exposed portion 430c1 in the axial direction (lengthwise) of the LED filament is greater than or equal to the length of the second exposed portion 430c2 in the axial direction of the LED filament, ensuring electrical connection stability and uniform force distribution during conductor bending. As shown in Figure 1F , the exposed portion includes only the first exposed portion 430c1. The length of the first exposed portion 430c1 in the axial direction of the LED filament is less than or equal to the distance between adjacent LED chips within any LED segment 402 / 404. When the LED filament bends, the stress generated during bending is concentrated on the conductor segment, reducing the risk of breakage of the wires connecting adjacent LED chips. As shown in Figure 1G , the exposed portion includes only the second exposed portion 430c2, which alleviates stress concentration on the conductor. The length of the second exposed portion 430c2 in the axial direction of the LED filament is less than or equal to the distance between adjacent LED chips within any LED segment 402 / 404. Because a portion of the conductor is located between adjacent transparent layers, the transparent layers' support for the conductor is ensured to be stable.

[0104] Referring to Figure 1H , an LED filament 400 comprises a light conversion layer 420; LED segments 402 and 404; electrodes 410 and 412; and a conductive segment 430 for electrically connecting adjacent LED segments 402 and 404. Each LED segment 402 and 404 includes at least one LED chip 442. The conductive segment 430 is electrically connected to the LED segments 402 and 404 via a second conductive wire 450. Specifically, the two LED chips 442 located within adjacent LED segments 402 and 404 and closest to the conductive segment 430 are electrically connected to a conductor 430a within the conductive segment 430 via the second conductive wire 450. The conductive segment 430 includes a conductor 430a that connects the LED segments 402 and 404. The conductor 430a may be a conductive metal sheet or strip, such as a copper or iron sheet. The shortest distance between two LED chips 442 within adjacent LED segments 402 and 404 is greater than the distance between two adjacent LED chips within each LED segment 402 / 404. The LED chips are electrically connected via a first conductive wire 440, which is shorter than the length of the conductor 430a. When the two LED segments are bent, the conductor segments bear a larger force, preventing the generated stress from breaking. A light conversion layer 420 covers at least two sides of the LED chips 442 and the electrodes 410 / 412. The light conversion layer 420 exposes a portion of the electrodes 410 / 412. The light conversion layer 420 includes a top layer (not shown) and a carrier layer, which includes a base layer 420b and a transparent layer 420c. The LED chips 442 within each LED segment 402 / 404 are arranged along the radial direction (or widthwise direction) of the LED filament. Each LED chip 442 within each LED segment 402 / 404 is connected to the conductor 430a and / or the electrodes 410 / 412. In this embodiment, the base layer 420b and the transparent layer 420c have equal widths in the radial direction of the LED filament, resulting in a large contact area between the base layer 420b and the transparent layer 420c, making delamination less likely. In other embodiments, the base layer 420b has a smaller width in the radial direction of the LED filament than the transparent layer 420c. A top layer (not shown) contacts the base layer and the transparent layer 420c, and the base layer 420b is thinner than the top layer. Heat emitted from the LED chip is transferred simultaneously to the top layer and the transparent layer via the base layer, thereby improving the heat dissipation efficiency of the LED filament. Furthermore, the top layer and the transparent layer fully encase the base layer, protecting it from external environmental influences. Furthermore, when the LED filament is bent, the top layer's multiple side surfaces provide protection, reducing the probability of breakage of the second conductive wire 450 and improving product yield.

[0105] Referring to Figures 1I to 1J , an LED filament comprises a light conversion layer 420, LED segments 402 / 404, and electrodes 410 / 412. LED segments 402 / 404 include at least one LED chip 442. Adjacent LED chips 442 within the LED filament are electrically connected to each other and to the electrodes 410 / 412. Adjacent LED chips 442 are connected via wires 440. The light conversion layer 420 covers all surfaces of the wires 440, effectively preventing them from being exposed and accidentally touched by equipment or workers during winding. The light conversion layer 420 encapsulates the LED segments 402 / 404 and electrodes 410 / 412, while exposing at least a portion of the two conductive electrodes 210 and 212. The light conversion layer 420 includes a top layer 420a and a carrier layer. The top layer 420a covers all surfaces of the wires 440, with a certain distance between the wires 440 and the carrier layer. The top layer 420a and the supporting layer can be a layered structure of at least one layer respectively. The top layer 420a includes a phosphor layer 420a1 and a phosphor film layer 420a2, or the top layer 420a includes a phosphor layer 420a1 and a phosphor glue layer 420a2. The thermal conductivity of the phosphor layer 420a1 is greater than that of the phosphor film layer (or phosphor glue layer) 420a2. The phosphor layer 420a1 is in contact with at least one surface of the LED chip 42. On the one hand, the heat generated by the LED chip 442 is directly transferred to the phosphor film layer / phosphor glue layer 420a2 through the phosphor layer 420a1. Since the phosphor layer 420a1 does not contain non-conductive or poorly thermally conductive silicone, it has good thermal conductivity. The heat generated by the LED chip 442 can be quickly transferred to the phosphor film layer / phosphor glue layer 420a2 through the phosphor layer 420a1, preventing heat from accumulating near the LED chip 442. The phosphor film layer or phosphor glue layer 420a2 is in contact with the phosphor layer 420a1; on the other hand, the light emitted by the LED chip 442 excites the phosphor layer 420a1 to produce a color of light (for example, red light), and the phosphor layer 420a1 has a weak absorption capacity for the light emitted by the LED chip, so the light loss caused is small and does not affect the luminous flux of the LED bulb. The light emitted by the LED chip 442 is converted into white light after passing through the phosphor film layer or phosphor glue layer 420a2, and the light generated after exciting the phosphor layer 420a1 can supplement the white light with color light in a certain wavelength range (for example, red light with a wavelength of 610nm-650nm), so that the color rendering index (Ra) of the LED bulb is at least greater than 85 and / or R9 is greater than 45. After the LED bulb is lit, the color gamut of the color reproduction of the lighting environment can be increased, thereby improving the quality of the lighting environment.Furthermore, the phosphor layer 420a1 only covers the upper surface (or light-emitting surface) of the LED chip 442 or the phosphor layer 420a1 only contacts the upper surface (or light-emitting surface) of the LED chip 442. Since the light-emitting angle (or beam angle) of the LED chip 442 is generally 120 degrees and the phosphor is generally more expensive, the phosphor layer 420a1 only covers the upper surface (or light-emitting surface) of the LED chip, which can achieve the above-mentioned light-emitting effect and reduce the material cost of the LED bulb.

[0106] In some embodiments, phosphor layer 420a1 wraps a portion of wire 440, and phosphor film / phosphor glue layer 420a2 wraps another portion of wire 440. Together, phosphor layer 420a1 and phosphor film (or phosphor glue) 420a2 cover wire 440. Phosphor layer 420a1 may be harder than phosphor film / phosphor glue layer 420a2, or less flexible or bendable than phosphor film / phosphor glue layer 420a2. The connection between wire 440 and LED chip 442 is wrapped by phosphor layer 420a1, thereby reducing the bendability of the connection. Furthermore, the protective effect of phosphor layer 420a1 further reduces the risk of breakage at the connection between wire 440 and LED chip 442. In addition, the phosphor layer 420a1 and the phosphor film layer / phosphor glue layer 420a2 can provide dual protection for the wire 440, preventing the wire from breaking when the LED filament is bent. The quality of the welding wire is mainly determined by five points: A, B, C, D, and E. A is the connection between the chip pad 4401 and the gold ball 4403, B is the connection between the gold ball 4403 and the wire 440, C is between the two sections of the wire 440, D is the connection between the wire 440 and the second solder point weld bar 4402, and E is between the second solder point weld bar 4402 and the surface of the chip 442. Because point B is the first bending point of the wire 440 when it is traced, the wire diameter of the wire 440 at point D is thinner, so the wire 440 is easy to break at points B and D. Therefore, for example, when implementing As shown in the structure of Figure 1K, when the LED filament is bent, the part of the wire 440 located in the phosphor film layer / phosphor glue layer 420a2 is mainly subjected to force, while the part of the wire 440 located in the phosphor layer 420a1 is subjected to less force. Therefore, the thickness of the phosphor layer 420a1 can be smaller than the thickness of the phosphor film layer (or phosphor glue) 420a2. The phosphor layer 420a1 can cover points B and D of the wire. Due to the material properties of the phosphor layer 420a1 (hardness, flexibility or bendability), the wire can be prevented from breaking at points B and D.

[0107] As shown in FIG. 1I , each LED chip 442 is covered with a phosphor layer 420a1. A portion of the LED filament has a phosphor film layer (or phosphor glue layer) 420a2 in direct contact with the carrier layer. In some embodiments, this portion is located between two adjacent LED chips 442. The phosphor layer 420a1 only covers the LED chip 442, which can achieve the above-mentioned luminous effect and reduce the production cost of the LED bulb.

[0108] As shown in FIG1J , the phosphor layer 420a1 extends along the length of the LED filament. The phosphor layer 420a1 can be applied to a single LED filament or to multiple LED filaments simultaneously, simplifying the coating process and improving production efficiency. In some areas of the LED filament, the phosphor layer 420a1 is in direct contact with the carrier layer. In some embodiments, this area is located between two adjacent LED chips. Due to the increased area of ​​the phosphor layer 420a1 (which also increases the heat dissipation area) and the relatively thin phosphor layer 420a1, heat generated by the LED chip 442 is easily transferred from the phosphor layer 420a1 to the phosphor film layer (or phosphor glue layer) 420a2.

[0109] In some embodiments, the phosphor layer 420a1 includes phosphor and silica gel. The viscosity of the silica gel is no greater than 1600 mPa·s (at 25°C and 10 rpm), allowing the phosphor to mix evenly with the silica gel, resulting in a relatively smooth phosphor layer after application. If the viscosity of the silica gel is greater than 1500 mPa·s (at 25°C and 10 rpm), a diluent (e.g., kerosene) may be added when preparing the phosphor layer 420a1. The silica gel and diluent are first mixed to reduce the viscosity, and then mixed with the phosphor. After application, the diluent evaporates (e.g., by air drying), forming the phosphor layer 420a1 on the surface of the LED chip 442. A phosphor with a narrow half-peak width (half-peak width no greater than 50 nm) can be used. A narrow half-peak width provides strong energy and high excitation efficiency. In order to supplement red light, general lighting equipment combines some phosphors in low-peak wavelength bands (peak wavelength not greater than 630nm) with some high-peak wavelength bands (peak wavelength greater than 640nm). However, these phosphors generally have a wide half-peak wavelength width and relatively low excitation efficiency. After the lighting equipment is turned on, the R9 value is small, and the color gamut of color reproduction is reduced. In one embodiment, a phosphor with a half-peak wavelength (FWHM) of 10 to 30nm and a peak wavelength of 630-635nm can be used to supplement red light within a certain peak wavelength range, thereby increasing the color gamut of color reproduction.

[0110] Next, the chip bonding design for the LED filament will be described. Figure 1L shows a top view of an unbent LED filament in one embodiment of the present application, with the top layer removed. The LED filament includes a first LED chip unit 202, a second LED chip unit 204, and electrodes 210 / 212. The first LED chip unit 202 and the second LED chip unit 204 are electrically connected to the electrodes 210 / 212, respectively. The first LED chip unit 202 extends parallel to or substantially parallel to the second LED chip unit 204, and the first and second LED chip units 202 and 204 are connected in parallel. The first and second LED chip units 202 and 204 each include a plurality of LED chips 442. The spacing between adjacent LED chips 442 in the first LED chip unit 202 is equal to the spacing between adjacent LED chips 442 in the second LED chip unit 204. In other embodiments, the spacing between adjacent LED chips 442 in the first LED chip unit 202 may not be equal to the spacing between adjacent LED chips 442 in the second LED chip unit 204. The light conversion layer 420 has a first end and a second end opposite to the first end. The LED chip 442 is located between the first end and the second end. The LED chip 442 closest to the first end in the first LED chip unit 202 is denoted as LED chip a1. The LED chips 442 from the first end to the second end are LED chips a2, a3, ..., a m , m is an integer; the LED chip 442 closest to the first end in the second LED chip unit 204 is recorded as LED chip b1, and the LED chips 442 from the first end to the second end are LED chips b2, b3, ... b n , n is an integer, LED chip b in the length direction of LED filament n Located in LED chip a m With LED chip a m+1 Between, and LED chip a m The projection in the width direction of the LED filament and the LED chip b nThe projections along the width of the LED filament do not overlap (n = m). That is, the LED chips 442 of the first LED chip unit 202 and the LED chips 442 of the second LED chip unit 204 are staggered along the length of the LED filament. When using the same number of LED chips, the longer the LED filament, the greater the spacing between adjacent LED chips. When the filament is lit, the light spots (or graininess) observed by the naked eye become more noticeable, seriously affecting the user's visual comfort. Furthermore, for LED filaments of the same length, the greater the number of LED chips, the smaller the spacing between adjacent LED chips, and the heat generated by adjacent LED chips can affect each other. To ensure that the LED filament has excellent light-emitting effect and heat dissipation performance, the first LED chip unit 202 and the second LED chip unit 204 are connected in parallel in this embodiment. The LED chip 442 in the second LED chip unit 204 is located between the two adjacent LED chips 442 in the first LED chip unit 202. Since the light emitted by the second LED chip unit 204 can supplement the light spot generated by the first LED chip unit 202, the light-emitting effect of the LED filament is improved. In addition, compared with LED filaments with the same LED filament length and number of LED chips, the distance between the two adjacent LED chips in the first LED chip unit 202 and the second LED chip unit 204 is larger, the heat generated by the adjacent LED chips is not easy to affect each other, and the junction temperature of the LED filament is reduced.

[0111] In another embodiment, the projections of the LED chip 442 in the first LED chip unit 202 and the LED chip 442 in the second LED chip unit 204 in the length direction of the LED filament have overlapping areas. m With LED chip b n The projections in the length direction of the LED filament have overlapping areas, because in the width direction of the LED filament, the LED chip a m With LED chip b n The spacing between the LED chips is reduced, the width of the LED filament is narrowed, and the width of the LED filament is close to that of the traditional tungsten filament lamp. The LED filament is more beautiful when wound. m 、LED chip b n They have multiple side faces, and in the length direction of the LED filament, the LED chip b n One side of the LED chip is located at m One side S1 and LED chip a m+1 In one embodiment, the side S1 is opposite to the side S2. In one embodiment, in the width direction of the LED filament, the LED chip a m 、LED chip b nThe widths of the LED filament are Wa and Wb respectively. The width W of the LED filament is not less than the sum of Wa and Wb, that is, W≥Wa+Wb.

[0112] In one embodiment, the LED chip has a first light-emitting surface and a second light-emitting surface, the first light-emitting surface and the second light-emitting surface are opposite to each other, the light emitted from the first light-emitting surface (front side) is toward the top layer, and the light emitted from the second light-emitting surface (back side) is toward the supporting layer, the luminous flux of the light emitted from the front side of the LED chip is equal to or approximately equal to the luminous flux of the light emitted from the light-emitting surface of the LED chip (the absolute value of the difference in luminous flux between the front and back sides is ≤30lm), the brightness difference between the front and back sides of the LED chip is small, the above-mentioned LED chip is used in the LED filament, and the light is evenly emitted in all directions after the LED filament is wound, and the LED bulb has an excellent light-emitting effect.

[0113] FIG1M is a top view of an unbent LED filament in one embodiment of the present application, with the top layer removed. The LED filament includes electrodes 210 / 212, an LED chip 442, and a conductive wire 440. Multiple LED chips 442 are arranged in two rows on the LED filament (i.e., adjacent LED chips 442 are staggered along the width of the LED filament). The two rows of LED chips 442 are arranged along the length of the LED filament. The LED chips 442 are connected in series. Adjacent LED chips 442 along the length of the LED filament are connected by conductive wire 440. In FIG1M , the LED chip 442 closest to the electrode 210 along the length of the LED filament is electrically connected to the electrode 210 via the first conductive portion 240. The LED chip 442 closest to the electrode 212 along the length of the LED filament is electrically connected to the electrode 210 via the first conductive portion 240. The first conductive portion 240 can be a conductive wire.

[0114] In this embodiment, the LED chips 442 have a length dimension a along the length direction of the filament. The ratio of the sum of the lengths a of all LED chips 442 (i.e., Σa) to the length of the LED filament is greater than 0.5, 0.6, 0.65, or 0.7. This ensures the density of the LED chips 442 along the length direction of the LED filament, thereby increasing the total luminous flux and effectively reducing the graininess of the light output. Furthermore, because adjacent LED chips 442 are staggered along the width direction of the LED filament, the LED filament can have better bendability while maintaining the same spacing between the LED chips. Conversely, if the ratio of the sum of the lengths of all LED chips 442 to the length of the LED filament is greater than 0.5, 0.6, 0.65, or 0.7, and the LED chips 442 are arranged in a single row, the LED filament may have poor bendability and cannot be bent normally, thereby limiting the shape of the filament.

[0115] Please continue to refer to Figures 2A to 2C. Figure 2A is a schematic perspective partial cross-sectional view of an embodiment of an LED filament of the present application; Figure 2B is a schematic bottom view of Figure 2A; and Figure 2C is a schematic partial cross-sectional view taken along line AA in Figure 2A. The LED filament 300 includes a plurality of LED chip units 202, 204, at least two conductive electrodes 210, 212, and a light conversion layer 220. The LED chip units 202, 204 are electrically connected to each other. The conductive electrodes 210, 212 are arranged corresponding to the LED chip units 202, 204 and are electrically connected to the LED chip units 202, 204 via a first conductive portion 240. The light conversion layer 220 encapsulates the LED chip units 202, 204 and the conductive electrodes 210, 212, with at least a portion of the two conductive electrodes 210, 212 exposed. The light conversion layer 220 includes silicone, phosphor, and heat dissipation particles. In some embodiments, the LED chip unit 202 / 204 includes at least one LED chip, and the phosphor concentration corresponding to each surface of the LED chip is the same, so that the light conversion rate of each surface is the same, and the light uniformity of the LED filament is good.

[0116] The LED chip unit 202 / 204 includes at least one LED chip. Each LED chip unit 202 / 204 has a first electrical connection portion 206a and a second electrical connection portion 206b. Along the length of the LED filament, the distance between the first connection portions 206a of two adjacent LED chip units 202 / 204 is greater than the distance between two adjacent LED chip units 202 / 204. In some embodiments, along the length of the LED filament, the distance between the first connection portion 206a and the second connection portion 206b of two adjacent LED chip units 202 / 204 is greater than the distance between the two adjacent LED chip units 202 / 204. At least a portion of the first electrical connection portion 206a and the second electrical connection portion 206b contacts the light conversion layer 220. The first electrical connection portion 206a and the second electrical connection portion 206b are located on the same side of the LED chip unit 202 / 204.

[0117] In one embodiment, the second electrical connection portion 206b of the LED chip unit 202 is electrically connected to the first electrical connection portion 206a of the LED chip unit 204. For example, the second electrical connection portion 206b of the LED chip unit 202 can be electrically connected to the first electrical connection portion 206a of the LED chip unit 204 through the second conductive portion 260. The second conductive portion 260 has an endpoint a and an endpoint b. The line connecting the endpoints a and b is a straight line ab, and the straight line ab intersects with the length direction p of the LED filament. In some embodiments, the light conversion layer 220 includes a top layer and a carrier layer (not shown). The top layer encapsulates the LED chip units 202 and 204 and the conductive electrodes 210 and 212, with at least a portion of the two conductive electrodes 210 and 212 exposed. The carrier layer includes a base layer, which includes an upper surface and a lower surface opposite the upper surface. The upper surface of the base layer is closer to the top layer relative to the lower surface of the base layer. At least one of the first conductive portion 240 and the second conductive portion 260 is in contact (directly or indirectly) with the upper surface of the base layer. When the LED filament bends, the radius of curvature of the base layer after bending under force is relatively small, making the first and second conductive portions less likely to break. In one embodiment, the first electrical connection portion 206a and the second electrical connection portion 206b are in contact (directly or indirectly) with the upper surface of the base layer. The LED chip unit can be a flip chip or a mini LED chip. Mini LED refers to LEDs with a package size in the range of 0.1-0.2 mm, also known as sub-millimeter light-emitting diodes. When the LED chip units are electrically connected, for example, the second electrical connection portion 206b of the LED chip unit 202 can be the positive connection point, and the first electrical connection portion 206a of the LED chip unit 204 can be the negative connection point. The second electrical connection portion 206b of the LED chip unit 202 can be electrically connected to the first electrical connection portion 206a of the LED chip unit 204 via the second conductive portion 260. For another example, the second electrical connection portion 206b of the LED chip unit 202 can be the negative connection point, and the first electrical connection portion 206a of the LED chip unit 204 can be the positive connection point. The second electrical connection portion 206b of the LED chip unit 202 can be electrically connected to the first electrical connection portion 206a of the LED chip unit 204 via the second conductive portion 260. The first conductive portion 240 and the second conductive portion 260 can be in the form of wires or films, such as copper wires, gold wires, circuit films, or copper foil.

[0118] Please refer to Figures 3A to 3E, which are schematic diagrams of an embodiment of a method for manufacturing an LED filament according to the present application. The method for manufacturing an LED filament includes:

[0119] S20: Laying LED chip units 202, 204 and conductive electrodes 210, 212 on a carrier 280 (as shown in FIG3A);

[0120] S22A: Apply a top layer 220a to the portions of the LED chip units 202, 204 and the conductive electrodes 210, 212 that are not in contact with the carrier 280. Then, a curing (or solidification) process is performed on the LED chip units 202, 204 and the conductive electrodes 210, 212 coated with the top layer 220a, so that the top layer 220a is cured and covers the LED chip units 202, 204 and the conductive electrodes 210, 212 above the carrier, while exposing a portion of at least two conductive electrodes 210, 212 (as shown in FIG3B ). This curing process may be, for example, but not limited to, heating or ultraviolet (UV) irradiation.

[0121] S22B: There are several ways to flip the LED chip units 202, 204 and the conductive electrodes 210, 212 coated with the top layer 220a. One way is to simply place the LED chip units 202, 204 and the conductive electrodes 210, 212 on the carrier 280 without any adhesive relationship between them. The LED chip units 202, 204 and the conductive electrodes 210, 212 can be directly flipped, and the flipped semi-finished product can be placed back on the carrier 280.

[0122] Secondly, if a glue-like substance, such as photoresist used in semiconductor manufacturing or easily removable bonding adhesive, is placed between the carrier 280 and the LED chip units 202, 204, and the conductive electrodes 210, 212, this glue-like substance, after being properly baked, can temporarily secure the LED chip units 202, 204, and the conductive electrodes 210, 212 to the carrier 280. Therefore, before or after flipping the LED chip units 202, 204, and the conductive electrodes 210, 212 coated with the top layer 220a, the photoresist coated on the carrier 280 can be cleaned with acetone, or the bonding adhesive on the carrier can be removed with a corresponding solvent. This allows the LED chip units 202, 204, and the conductive electrodes 210, 212 coated with the top layer 220a to be separated from the carrier 280. Further cleaning can also be performed to remove any residual photoresist or bonding adhesive.

[0123] S24: electrically connecting adjacent LED chip units 202, 204 and LED chip units 202 / 204 to conductive electrodes 210, 212 (as shown in FIG3C);

[0124] S26: After step S24, the base layer 220b is coated on the portions of the LED chip units 202, 204 and the conductive electrodes 210, 212 not coated by the top layer 220a, and then cured (as shown in FIG3D).

[0125] Specifically, the base layer 220b and the chip units 202 and 204 may include a bonding adhesive to enhance adhesion. Furthermore, to ensure stable attachment of the chip units 202 and 204 to the base layer 220b, at least 80% of the bottom surface of each chip unit 202 and 204 attached to the base layer 220b is covered with bonding adhesive. Furthermore, 100% of the bottom surface of each chip unit 202 and 204 attached to the base layer 220b is covered with bonding adhesive.

[0126] After step S26, step S28 may be further included for cutting the LED chip units 202, 204 and the conductive electrodes 210, 212 wrapped with the light conversion layer 220, as indicated by the dotted lines in FIG3E . Thus, the cut elongated element becomes the LED filament 300. The cutting method in step S28 is not limited to that shown in FIG3E ; each two adjacent vertical rows of LED chip units 202, 204 may also be cut into a single LED filament.

[0127] In the LED filament preparation method of this embodiment, the top layer 220a and the base layer 220b can contain the same ratio of phosphor and silica. If the top layer 220a and the base layer 220b also contain oxide nanoparticles, the ratios of phosphor, silica, and oxide nanoparticles in the top layer 220a and the base layer 220b are the same. In other words, the top layer 220a and the base layer 220b are made of the same material. They are distinguished as the top layer 220a and the base layer 220b for convenience of description. Of course, in other embodiments, the ratios of phosphor, silica, and oxide nanoparticles in the top layer 220a and the base layer 220b may be different.

[0128] In one embodiment, the aforementioned base layer includes an organosilicon-modified polyimide, a thermal curing agent, heat dissipation particles, and phosphors. The thermal curing agent is an epoxy resin, isocyanate, or a bisoxazoline compound, and the heat dissipation particles include silicon dioxide (SiO2), aluminum oxide (Al2O3), zirconium oxide (ZrO2), etc. In one embodiment, the amount of the thermal curing agent is 3-12% of the weight of the organosilicon-modified polyimide. The organosilicon-modified polyimide includes repeating units represented by the following general formula (I):

[0129]

[0130] In the general formula (I), Ar 1is a tetravalent organic group. The organic group has a benzene ring or an alicyclic hydrocarbon structure. The alicyclic hydrocarbon structure may be a monocyclic alicyclic hydrocarbon structure or an alicyclic hydrocarbon structure containing a bridged ring. The alicyclic hydrocarbon structure containing a bridged ring may be a bicyclic alicyclic hydrocarbon structure or a tricyclic alicyclic hydrocarbon structure. The organic group may also be a benzene ring structure or an alicyclic hydrocarbon structure containing an active hydrogen functional group, wherein the active hydrogen functional group is any one or more of a hydroxyl group, an amino group, a carboxyl group, an amide group, or a thiol group.

[0131] Ar 2 The organic group may be a divalent organic group having, for example, a monocyclic alicyclic hydrocarbon structure, or a divalent organic group containing an active hydrogen functional group, wherein the active hydrogen functional group is any one or more of a hydroxyl group, an amino group, a carboxyl group, an amide group or a thiol group.

[0132] R is each independently selected from methyl or phenyl.

[0133] n is 1 to 5, and preferably n is 1, 2, 3 or 5.

[0134] The number average molecular weight of general formula (I) is 5,000 to 100,000, preferably 10,000 to 60,000, and more preferably 20,000 to 40,000. The number average molecular weight is a polystyrene conversion value based on a calibration curve prepared using standard polystyrene using a gel permeation chromatography (GPC) apparatus. When the number average molecular weight is 5,000 or less, it is difficult to obtain good mechanical properties after curing, and in particular, the elongation tends to decrease. On the other hand, when it exceeds 100,000, the viscosity becomes too high, making it difficult to form the resin.

[0135] Ar 1 It is a component derived from dianhydride, and the dianhydride may include aromatic anhydride and aliphatic anhydride. The aromatic anhydride includes aromatic anhydride containing only benzene ring, fluorinated aromatic anhydride, aromatic anhydride containing amide group, aromatic anhydride containing ester group, aromatic anhydride containing ether group, aromatic anhydride containing sulfur group, aromatic anhydride containing sulfone group and aromatic anhydride containing carbonyl group, etc.

[0136] Ar 2 It is a component derived from diamines, which can be divided into aromatic diamines and aliphatic diamines. Aromatic diamines include aromatic diamines containing only benzene ring structures, fluorinated aromatic diamines, aromatic diamines containing ester groups, aromatic diamines containing ether groups, aromatic diamines containing amide groups, aromatic diamines containing carbonyl groups, aromatic diamines containing hydroxyl groups, aromatic diamines containing carboxyl groups, aromatic diamines containing sulfone groups, aromatic diamines containing sulfur groups, etc.

[0137] Adding different thermal curing agents will have different effects on the light transmittance of silicone modified polyimide.

[0138] Even when adding the same thermal curing agent, varying the addition amount can have varying effects on light transmittance. Table 1-1 shows that increasing the addition amount of BPA, a thermal curing agent, from 4% to 8% for a fully aliphatic silicone-modified polyimide improves light transmittance. However, increasing the addition amount to 12% results in little change in light transmittance. This suggests that light transmittance improves with increasing thermal curing agent addition, but once the increase reaches a certain level, the effect of adding more thermal curing agent on light transmittance becomes quite limited.

[0139] Table 1-1

[0140]

[0141] The phosphor composition as part of the top layer 420b includes a first phosphor, a second phosphor, a third phosphor, and a fourth phosphor. Under blue light excitation, the first phosphor has a peak wavelength of 490 to 500 nm and a full width at half maximum (FWHM) of 29 to 32 nm; under blue light excitation, the second phosphor has a peak wavelength of 520 to 540 nm and a full width at half maximum (FWHM) of 110 to 115 nm; under blue light excitation, the third phosphor has a peak wavelength of 520 to 540 nm and a full width at half maximum (FWHM) of 110 to 115 nm. The phosphor has a peak wavelength of 660-672 nm and a full width at half maximum (FWHM) of 15-18 nm. Under blue light excitation, the fourth phosphor has a peak wavelength of 600-612 nm and a full width at half maximum (FWHM) of 72-75 nm, or a peak wavelength of 620-628 nm and a full width at half maximum (FWHM) of 16-18 nm, or a peak wavelength of 640-650 nm and a full width at half maximum (FWHM) of 85-90 nm. The center particle size (D50) of any one of the first, second, third, and fourth phosphors is in the range of 15-20 μm. The D50 of the second and third phosphors is preferably in the range of 15-16 μm, and the D50 of the first and fourth phosphors is preferably in the range of 16-20 μm. When blue light excites phosphors, varying top layer thicknesses at the same phosphor concentration can affect the phosphor's half-peak width. In this embodiment, the thickness of the top layer 420b is 80-100 μm. The weight percentages of the various phosphors in the phosphor composition are as follows: 5.45-5.55% for the first phosphor, 70-88% for the second phosphor, 0.6-7% for the third phosphor, and the remainder for the fourth phosphor. The phosphors are blended at a specific phosphor-to-glue ratio, with phosphors of different peak wavelengths selected. The measured optical performance is shown in Table 1, using a blue LED chip with a peak wavelength of 451 nm, a full width at half maximum (FWHM) of 16.3 nm, and a current of 30 mA.

[0142] Table 1

[0143]

[0144] From Nos. 1-4 in Table 1, it can be seen that the content of the third and fourth phosphors in the phosphor composition affects the luminous efficacy (Eff), average color rendering index (Ra), and saturated red (R9). From Nos. 1 and 2, it can be seen that increasing the content of the fourth phosphor with a peak wavelength of 670nm increases Eff, while Ra and R9 decrease. When replacing a phosphor with a peak wavelength of 652nm with a phosphor with a peak wavelength of 630nm, as can be seen from Nos. 3 and 4 in Table 1, increasing the content of the fourth phosphor with a peak wavelength of 670nm decreases Eff, while Ra and R9 increase. Therefore, when selecting fourth phosphors with different peak wavelengths, the amounts of the third and fourth phosphors can be adjusted to achieve optimal luminous performance.

[0145] The ratio of phosphor to glue

[0146] The same phosphor was selected and the ratio of the phosphor composition to the glue was adjusted as shown in Table 2. As can be seen from Table 2, different ratios of the phosphor composition to the glue resulted in different Eff, Ra, R9, and CCT. The higher the proportion of the phosphor composition to the glue, the lower the Eff, Ra, and CCT, while R9 showed a trend of decreasing and then increasing. Furthermore, when the phosphor composition is combined with glue (e.g., silica gel) as the top layer of an LED filament, during the production of the top layer, the phosphor composition has a greater specific gravity than the silica gel, which can cause significant sedimentation of the phosphor, resulting in a color temperature shift in the white light LED. The greater the proportion of the phosphor, the more phosphor sedimentation occurs, and the more severe the color temperature shift. Therefore, the weight ratio of the phosphor composition to the glue in the top layer is 0.2 to 0.3:1, preferably 0.25 to 0.3:1. In one embodiment, a certain amount of hollow glass microspheres can be added to the phosphor composition. As the phosphor settles, the glass microspheres float upward. This floating process reduces the backscattering / emission of light, offsetting the light scattering effect of the phosphor settling. This can mitigate color temperature shift. Furthermore, because the microspheres absorb little visible light, the addition of the glass microspheres has a minimal effect on the initial brightness of the white LED. The mass ratio of the glass microspheres to the phosphor composition is 1:5-15, and preferably the weight ratio is 1:10-15.

[0147] Table 2

[0148]

[0149] In one embodiment, an LED filament is provided. The LED filament is made of the phosphor composition described above and a blue light chip. The blue light chip has a peak wavelength of 450 to 500 nm and a half-peak width of 15 to 18 nm.

[0150] In some embodiments, the phosphor composition comprising the top layer 420b includes a first phosphor, a second phosphor, and a third phosphor. Under blue light excitation, the first phosphor has a peak wavelength of 500-550 nm and a full width at half maximum (FWHM) of 100-130 nm. Under blue light excitation, the second phosphor has a peak wavelength of 580-620 nm and a full width at half maximum (FWHM) of 70-90 nm. Under blue light excitation, the third phosphor has a peak wavelength of 620-670 nm and a full width at half maximum (FWHM) of 70-95 nm. The center particle size (D50) of each of the first, second, and third phosphors is in the range of 15-20 μm, preferably 15-16 μm for the first phosphor and 16-20 μm for the second and third phosphors. When blue light excites the phosphor, different top layer thicknesses for the same phosphor concentration will affect the phosphor's half-peak width. In this embodiment, the thickness of the top layer 420b is 80 to 100 μm. The amount of the first phosphor in the phosphor composition is less than or equal to ten times the sum of the amounts of the second and third phosphors, i.e., the amount of the first phosphor is ≤ 10*(amount of the second phosphor + amount of the third phosphor). The weight ratio of the phosphor composition to the silica gel in the top layer is 0.4 to 0.8:1. The closer the amount of the phosphor composition to the silica gel, the higher the light conversion efficiency of the LED chip. Furthermore, the contact area between the phosphor and the LED chip increases, improving the heat dissipation efficiency of the LED chip.

[0151] As shown in FIG1N , an LED filament is provided in one embodiment. Its basic structure can be similar to that of the aforementioned embodiments, namely, the LED filament includes a light conversion layer 420, an LED chip 442, and an electrode 410. The LED chips 442 are connected to each other via a first conductive wire 440, and the LED chip 442 and the electrode 410 are connected via a second conductive wire 450. The light conversion layer 420 surrounds the LED chips 442 and at least a portion of the electrode 410. Furthermore, the basic structure or material composition of the light conversion layer 420 in this embodiment can also be similar to that of the aforementioned embodiments. The LED chips 442 in this embodiment constitute an LED segment 402. In this embodiment, the junction of the light conversion layer 420 and the electrode 410 forms a joint 460. The joint 460 surrounds at least a portion of the electrode 410 and does not cover (or include) the LED chip 442. In this embodiment, one end of the electrode 410 is exposed outside the joint 460, while the other end is surrounded / covered by the joint 460. The joint 460 extends beyond the end of one end of the electrode 410 along the length of the LED filament and does not cover any of the LED chips 442 in the radial projection of the LED filament. The ratio of phosphor and / or heat sink particles in the light conversion layer 420 at the joint 460 is lower than that of the light conversion layer 420 at the LED segment 402. By reducing the ratio of phosphor and / or heat sink particles in the light conversion layer 420 at the joint 460 (increasing the ratio of silicone), its flexibility is increased, preventing cracking at the joint 460 due to stress generated by bending the electrode 410. Otherwise, cracking at the joint 460 could cause the second conductive wire 450 at the joint 460 to break.

[0152] As shown in FIG1N , the junction 460 includes a sleeve 470. The phosphor content of the sleeve 470 is lower than that of the light conversion layer 420 at the LED segment 402. The provision of the sleeve 470 reduces the overall phosphor content of the light conversion layer 420 at the junction 460. Specifically, the phosphor content of the light conversion layer 420 covered by the sleeve 470 (which may include the sleeve 470 itself) is lower than that of the light conversion layer 420 at the LED segment 402. In some embodiments, the sleeve 470 does not contain phosphor or heat dissipation particles.

[0153] A portion of the sleeve 470 is directly positioned over the electrode 410, while another portion is positioned over the light conversion layer 420 at the junction 460. The light conversion layer 420 enclosed by the sleeve 470 and the sleeve 470 itself together form the junction 460. Structurally, the sleeve 470 prevents cracking of the light conversion layer 420 at the junction 460. One end of the sleeve 470 extends beyond the end of the electrode 410 along the filament's length. The sleeve 470 can be positioned over either or both ends of the LED filament. The area covering the light conversion layer 420 should occupy less than 10% of the LED filament's length. In other words, the total length of the sleeve 470 covering the light conversion layer 420 should be less than 10% of the total length of the LED filament (excluding the electrode 410). This ensures that the light-emitting area and total brightness of the LED filament are not affected by the sleeve 470, while also ensuring that the sleeve 470 reinforces the LED filament's structure.

[0154] In some embodiments, the sleeve 470 may be made of a transparent or translucent material (i.e., a light-transmitting material) to reduce light loss when light passes through the sleeve 470. In some embodiments, the color of the sleeve 470 is the same or substantially the same as the color of the light conversion layer 420 to maintain the color consistency of the appearance of the filament. The sleeve 470 may be a heat shrink tube, that is, when the sleeve 470 is sleeved on the electrode 410 and the light conversion layer 420, the sleeve 470 is heated to shrink and be included on the electrode 410 and the light conversion layer 420. The sleeve 470 can be made of a thermoplastic material such as PVC, PE, PP, PET, OPP, PVDC, POF, etc. The above materials are all existing technologies and will not be described in detail here.

[0155] In some embodiments, glue is applied to the outside of the light conversion layer 420 at the joint 460 to form the aforementioned sleeve 470. When the sleeve 470 is formed by glue, it may not directly cover at least a portion of the surface of the electrode 410, or it may directly cover at least a portion of the surface of the electrode 410.

[0156] As shown in FIG1O , in some embodiments, the phosphor ratio of the light conversion layer 420 at the joint 460 is lower than the phosphor ratio of the light conversion layer 420 of the LED segment 402, and the silicone ratio of the light conversion layer 420 at the joint 460 is higher than the silicone ratio of the light conversion layer 420 of the LED segment 402, so that the light conversion layer 420 at the joint 460 has better bendability, thereby reducing the risk of cracking.

[0157] Referring to FIG. 1P , in one embodiment, the electrode 410 includes a second portion 4102 encased or covered by the light conversion layer 420 and a first portion 4101 exposed outside the light conversion layer 420. The second portion 4102 exhibits superior bending properties to the first portion 4101 along the length of the LED filament. In other words, when the same force is applied to the first and second portions 4101, the first portion 4101 bends less than the second portion 4102. This allows the second portion 4102 to have bending properties closer to those of the light conversion layer 420, reducing the likelihood of stress-induced fracture of the light conversion layer 420 when the LED filament is bent.

[0158] In this embodiment, the first portion 4101 and the second portion 4102 have different bending properties due to their different structural designs. Specifically, the area per unit length of the second portion 4102 is smaller than the area per unit length of the first portion 4101, so that the second portion 4102 has better bending properties.

[0159] The second portion 4102 includes an end 41021, a curved section 41022, and a connecting section 41023. The end 41021, the curved section 41022, and the connecting section 41023 are sequentially arranged along the length of the second portion 4102, and the connecting section 41023 is connected to the first portion 4101. The area per unit length of the curved section 41022 is smaller than the area per unit length of the end 41021 and the connecting section 41023, respectively. This ensures that when the second portion 4102 is subjected to force, the primary bending portion is located in the curved section 41022.

[0160] The area per unit length of the connecting section 41023 is larger than the area per unit length of the connecting section 41023 and the end 41021, respectively, so that the end of the light conversion layer 420 and the electrode 410 have a larger bonding area, thereby improving the bonding strength and preventing cracking at the bonding point between the end of the light conversion layer 420 and the electrode 410 when the LED filament is bent.

[0161] As shown in FIG1P , one or more grooves 41024 are provided on one or both sides of the bending section 41022 in the width direction to reduce the area per unit length of the bending section 41022, thereby improving overall bendability. Furthermore, the provision of grooves 41024 also enhances the bonding strength between the electrode 410 and the light conversion layer 420. Specifically, the material of the light conversion layer 420 can pass through the grooves 41024, so that the light conversion layers 420 on opposite sides of the electrode 410 are connected through the material of the light conversion layer 420 within the grooves 41024, forming a connection similar to a riveted connection.

[0162] As shown in FIG1R , one or more groups of holes 41025 are provided at the bend section 41022 to reduce the area per unit length of the bend section 41022. Furthermore, the provision of holes 41025 can also enhance the bonding strength between the electrode 410 and the light conversion layer 420. Specifically, the material of the light conversion layer 420 can pass through the holes 41025, so that the light conversion layer 420 on the front and back sides of the electrode 410 is connected through the light conversion layer 420 material within the holes 41025.

[0163] As shown in Figures 1P and 1Q , through-holes 41026 can be provided at the end 41021 of electrode 410 to enhance the bonding strength between end 41021 and light conversion layer 420. Material from light conversion layer 420 can pass through through-holes 41026, allowing the light conversion layer 420 on the front and back sides of electrode 410 to be connected via the material from light conversion layer 420 within through-holes 41025, forming a connection similar to a riveted connection.

[0164] As shown in Figures 1P and 1R, the end 41021 of electrode 410 is configured with a curved surface 41027 to prevent stress concentration caused by the sharp corner at end 41021, which could cause cracking or even breakage of light conversion layer 420. In some embodiments, end 41021 is configured as a spherical surface to achieve the same technical effect as described above.

[0165] In some embodiments, the second portion 4102 and the first portion 4101 are made of different materials, so that the second portion 4102 has better bending performance than the first portion 4101.

[0166] As shown in FIG. 1S , in some embodiments, the thickness (average thickness) of the second portion 4102 is smaller than the thickness (average thickness) of the first portion 4101 , such that the second portion 4102 has better bending properties than the first portion 4101 .

[0167] As shown in FIG. 1T , an embodiment provides an LED filament having the same basic structure as the aforementioned embodiments. Specifically, the LED filament includes a light conversion layer 420, an LED chip 442, and an electrode 410. The LED chips 442 are connected to each other via a first conductive wire 440, and the LED chips 442 and the electrode 410 are connected via a second conductive wire 450. The light conversion layer 420 encapsulates the LED chips 442 and at least a portion of the electrode 410. Furthermore, the basic structure and material composition of the light conversion layer 420 in this embodiment may also be similar to those in the aforementioned embodiments.

[0168] In this embodiment, the first conductive wire 440 has a first portion 44001. The first portion 44001 is located between the two LED chips 442 along the length of the LED filament (in the projection direction of the LED filament's width / thickness, the first portion 44001 is located between the tangent lines of the two LED chips 442). When the LED filament bends, the area between the LED chips 442 is the primary bending region (the area containing the LED chips 442 is less susceptible to bending). To reduce the risk of breaking the first portion 44001 of the first conductive wire 440 when the LED filament bends, the length L1 of the first portion 44001 is configured to be greater than the distance D1 between the two LED chips 442. In other words, the length L1 of the first portion 44001 is configured to be greater than the projection length of the first portion 44001 along the width of the LED filament. This design provides the first conductive wire 440 with more margin for bending, preventing breakage.

[0169] In some embodiments, the ratio of the length L1 of the first portion 44001 to the distance D1 between the two groups of LED chips 442 (or the projected length of the first portion 44001 along the width of the LED filament) is greater than 1.1, 1.2, 1.3, or 1.4. This ensures that when the LED filament is bent, the first portion 44001 has sufficient length to deform with the bend, preventing the first portion 44001 from breaking. In some embodiments, the length L1 is greater than the projected length D1 of the first portion 44001 along the width of the LED filament.

[0170] In some embodiments, the ratio of the length L1 of the first portion 44001 to the distance D1 between the two groups of LED chips 442 (or the projected length of the first portion 44001 along the width of the LED filament) is less than 2. If the length of the first portion 44001 is too long, the light conversion layer 420 may not be effectively covered, and the first conductive wire 44001 may even be exposed outside the light conversion layer 420. Furthermore, an excessively long first portion 44001 may result in material waste.

[0171] In some embodiments, the first portion 44001 is configured to be arc-shaped so that its length L1 is greater than the distance D1 between the two groups of LED chips 442 (the projected length of the first portion 44001 in the width direction of the LED filament).

[0172] As shown in FIG. 1U , in some embodiments, the first portion 44001 is configured to be wavy or spiral so that its length is greater than the distance between the two groups of LED chips 442 (the projected length of the first portion 44001 in the width direction of the LED filament).

[0173] As shown in FIG. 1V , in some embodiments, the first portion 44001 (or the entire first conductive wire 440 ) is generally "m"-shaped when viewed from the side of the LED filament. This allows the first portion 44001 of the first conductive wire 440 to be longer per unit length, providing a greater buffer when the LED filament bends, thereby preventing the first portion 44001 from being broken.

[0174] When the LED filament shown in Figures 1T to 1V is bent, the side of the LED chip 442 with the first conductive wire 440 is typically positioned outward (i.e., facing the exterior of the lamp body), while the other side is positioned inward (i.e., facing the interior of the lamp body). As shown in Figures 1T to 1V , both sides of the LED filament are typically bent downward along their length, so that the side of the LED chip 442 with the first conductive wire is positioned outward (i.e., facing the exterior of the lamp body). The arrangement of the first conductive wire 440 in the embodiments shown in Figures 1T to 1V ensures excellent bendability of the LED filament and prevents the first conductive wire 440 from breaking due to excessive bending. For example, the LED filament can be bent to a shape with a radius of curvature at its maximum point of curvature less than 10 mm, 8 mm, or 5 mm. Considering that the maximum curvature of the bent LED filament is not necessarily a circular arc, it can be expressed as follows: assuming that the LED chip 422 is electrically connected via conductive wires, the maximum inscribed circle radius of the bent LED filament at its maximum point of curvature is less than 15 mm, 10 mm, or 8 mm. In other words, when the LED filament in this embodiment uses a first conductive wire 440 to electrically connect to the LED chips 442, the maximum inscribed radius of the curved portion of the LED filament can be less than 15 mm, 10 mm, or 8 mm, while also ensuring that the first conductive wire 440 is not broken. Conventional LED filaments that use flexible substrates to support and electrically connect LED chips lack conductive wires, eliminating the risk of wire breakage. While these filaments may have a greater bending range, they are clearly not comparable.

[0175] In this embodiment, after the LED filament is bent, the maximum inscribed circle at the point of maximum curvature should be larger than 3 or 3.5 mm to reduce the risk of breaking the first conductive wire 440 due to excessive bending.

[0176] To ensure or further increase the bendability of the LED filament, the position of the first conductive wire 440 can also be adjusted. When the LED filament is bent as described above (i.e., the side of the LED chip 442 with the first conductive wire 440 is positioned externally, while the other side is positioned internally), the radius of curvature of the portion of the LED filament closer to the outside of the bend increases, and the resulting deformation or tension within this portion also increases. Therefore, the first conductive wire 440 can be positioned as far away from the surface 401 of the LED filament in the width (or thickness) direction as possible. This surface 401 is the surface of the LED chip 442 with the first conductive wire 440. Using Figure 1V as an example, the shortest distance from the first conductive wire 442 to the surface 401 is L, and the width (or thickness) dimension of the LED filament is D. The ratio of L to D is at least greater than 0.1.

[0177] In this embodiment, the first conductive wire 440 has a second portion 44002. When projected across the width of the LED filament onto the corresponding LED chip 442, the second portion 44002 completely falls within the area defined by the LED chip 442. One end of the second portion 44002 is connected to the LED chip 442, while the other end is connected to the first portion 44001 (the first portion 44001 and the second portion 44002 may be integrally formed). In other words, one end of the second portion 44002 is connected to the LED chip 442, while the other end does not extend beyond the corresponding LED chip 442 along the length of the LED filament.

[0178] In this embodiment, the length L2 of the second portion 44002 is greater than the distance D2 from the connection point between the second portion 44002 and the LED chip 442 to the longitudinal end of the LED chip 442 (the projected length of the second portion 44002 along the width of the LED filament). When the LED filament bends, the bending of the first portion 44001 pulls on the second portion 44002. This arrangement of the second portion 44002 provides room for deformation, preventing the connection point between the second portion 44002 and the LED chip 442 from breaking due to the tension of the first portion 44001.

[0179] In this embodiment, the first conductive line 440 has two sets of second portions 44002 , and at least one of the sets of second portions 44002 is configured as described above.

[0180] In some embodiments, the ratio of the length L2 of the second portion 44002 to the distance D2 from the connection point between the second portion 44002 and the LED chip 442 to the end of the LED chip 442 in the longitudinal direction (the projected length of the second portion 44002 in the width direction of the LED filament) is greater than 1.15, 1.2, 1.3, or 1.4, thereby reducing the risk of the second portion 44002 being broken at the connection point with the LED chip 442 due to tension.

[0181] In some embodiments, the ratio of the length L2 of the second portion 44002 to the distance D2 from the connection point between the second portion 44002 and the LED chip 442 to the end of the lengthwise direction of the LED chip 442 (the projected length of the second portion 44002 in the widthwise direction of the LED filament) is less than 2. If the second portion 44002 is too long, the second portion 44002 will inevitably have a larger bending amplitude or occupy space in the widthwise direction of the LED filament, both of which will adversely affect the LED filament (for example, a larger bending amplitude may cause greater internal stress in the second portion 44002, while occupying space in the widthwise direction of the LED filament requires a thicker light conversion layer, resulting in a thicker LED filament).

[0182] In this embodiment, the ratio of the length L2 of the second portion 44002 to the distance D2 from the connection point between the second portion 44002 and the LED chip 442 to the end of the LED chip 442 in the longitudinal direction (the projected length of the second portion 44002 in the width direction of the LED filament) is greater than the ratio of the length L1 of the first portion 44001 to the distance D1 between the two groups of LED chips 442 (or the projected length of the first portion 44001 in the width direction of the LED filament). This can be expressed as follows:

[0183] L2 / D2>L1 / D1

[0184] Typically, when the LED filament is bent, the connection point between the second portion 44002 and the LED chip 442 is more susceptible to tension and breakage. Therefore, by setting L2 / D2>L1 / D1, the risk of breakage at the connection point between the second portion 44002 and the LED chip 442 can be reduced.

[0185] In some embodiments, the first portion 44001 and the second portion 44002 are both arc-shaped, and the curvature radius of the second portion 44002 is smaller than the curvature radius of the first portion 44001, so that the first portion 44001 and the second portion 44002 satisfy the above formula, that is, L2 / D2>L1 / D1.

[0186] In other embodiments, L1 / D1>L2 / D2 can also be set to ensure that when the LED filament bends, the first wire (i.e., the first part) in the area where the bending mainly occurs has sufficient buffer space to prevent it from being easily broken.

[0187] In this embodiment, the second conductive wire 450 can also be configured as described above. Specifically, the second conductive wire 450 includes a first portion 4501, which is located between the LED chip 442 and the electrode 410 along the length of the LED filament. When the LED filament bends, the area between the LED chip 442 and the electrode 410 may become one of the bending regions (the area containing the LED chip 442 and the electrode 410 is less susceptible to bending). To reduce the risk of the first portion 45001 of the second conductive wire 450 being broken when the LED filament bends, the length L3 of the first portion 4501 is configured to be greater than the distance D3 between the LED chip 442 and the electrode 410. In other words, the length L3 of the first portion 4501 is configured to be greater than the projected length of the first portion 4501 along the width of the LED filament.

[0188] In some embodiments, the ratio of the length L3 of the first portion 4501 to the distance D3 between the LED chip 442 and the electrode 410 (or the projected length of the first portion 4501 in the width direction of the LED filament) is greater than 1.1, 1.2, 1.3, or 1.4. This ensures that when the LED filament is bent, the first portion 4501 has sufficient length to deform with the bend, thereby preventing the first portion 4501 from being broken.

[0189] In some embodiments, the ratio of the length L3 of the first portion 4501 to the distance D3 between the LED chip 442 and the electrode 410 (or the projected length of the first portion 4501 along the width of the LED filament) is less than 2. If the length of the first portion 4501 is too long, the light conversion layer 420 may not be covered effectively, and the first conductive wire 4501 may even be exposed outside the light conversion layer 420. Furthermore, an excessively long first portion 4501 may result in material waste.

[0190] In some embodiments, the first portion 4501 is configured to be arc-shaped so that its length L3 is greater than the distance D3 between the LED chip 442 and the electrode 410 (the projected length of the first portion 44001 in the width direction of the LED filament).

[0191] As shown in FIG. 1U , in some embodiments, the first portion 4501 is configured to be wavy so that its length is greater than the distance between the LED chip 442 and the electrode 410 (the projected length of the first portion 44001 in the width direction of the LED filament).

[0192] In this embodiment, the second conductive wire 450 has a second portion 4502. When projected across the width of the LED filament onto the corresponding LED chip 442, the second portion 4502 completely falls within the area defined by the LED chip 442. One end of the second portion 4502 is connected to the LED chip 442, while the other end is connected to the first portion 4501 (the first portion 4501 and the second portion 4502 may be integrally formed). In other words, one end of the second portion 4502 is connected to the LED chip 442, while the other end does not extend beyond the corresponding LED chip 442 along the length of the LED filament.

[0193] In this embodiment, the length L4 of the second portion 4502 is greater than the distance D4 from the connection point between the second portion 4502 and the LED chip 442 to the longitudinal end of the LED chip 442 (the projected length of the second portion 4502 along the width of the LED filament). When the LED filament bends, the bending of the first portion 4501 pulls on the second portion 4502. This arrangement of the second portion 4502 provides room for deformation, preventing the connection point between the second portion 4502 and the LED chip 442 from breaking due to the tension of the first portion 4501.

[0194] In some embodiments, the ratio of the length L4 of the second portion 4502 to the distance D4 from the connection point between the second portion 4502 and the LED chip 442 to the end of the LED chip 442 in the longitudinal direction (the projected length of the second portion 4502 in the width direction of the LED filament) is greater than 1.15, 1.2, 1.3, or 1.4, thereby reducing the risk of the second portion 4502 being broken at the connection point with the LED chip 442 due to tension.

[0195] In some embodiments, the ratio of the length L4 of the second portion 4502 to the distance D4 from the connection point between the second portion 4502 and the LED chip 442 to the end of the lengthwise direction of the LED chip 442 (the projected length of the second portion 4502 in the widthwise direction of the LED filament) is less than 2. If the second portion 4502 is too long, the second portion 4502 will inevitably have a larger bending amplitude or occupy space in the widthwise direction of the LED filament, both of which will adversely affect the LED filament (for example, a larger bending amplitude may cause greater internal stress in the second portion 4502, while occupying space in the widthwise direction of the LED filament requires a thicker light conversion layer, resulting in a thicker LED filament).

[0196] In this embodiment, the ratio of the length L4 of the second portion 4502 to the distance D4 from the connection point between the second portion 4502 and the LED chip 442 to the end of the LED chip 442 in the longitudinal direction (the projected length of the second portion 4502 in the width direction of the LED filament) is greater than the ratio of the length L3 of the first portion 4501 to the distance D3 between the LED chip 442 and the electrode 410 (or the projected length of the first portion 4501 in the width direction of the LED filament). This can be expressed as follows:

[0197] L4 / D4>L3 / D3

[0198] Typically, when the LED filament is bent, the connection point between the second portion 4502 and the LED chip 442 is more susceptible to breaking due to tension. Therefore, by setting L4 / D4>L3 / D3, the risk of breaking the connection point between the second portion 4502 and the LED chip 442 can be reduced.

[0199] In some embodiments, the first portion 4501 and the second portion 4502 are both arc-shaped, and the curvature radius of the second portion 4502 is smaller than the curvature radius of the first portion 4501, so that the first portion 4501 and the second portion 4502 satisfy the above formula, that is, L4 / D4>L3 / D3.

[0200] In some embodiments, the second conductive wire 450 includes a third portion 4503. When projected onto the corresponding electrode 410 along the width of the LED filament, the third portion 4503 completely falls within the range defined by the electrode 410. One end of the third portion 4503 is connected to the electrode 410, while the other end is connected to the first portion 4501 (the first portion 4501 and the third portion 4503 may be integrally formed). In other words, one end of the third portion 4503 is connected to the electrode 410, while the other end does not extend beyond the corresponding electrode 410 along the length of the LED filament.

[0201] In this embodiment, the length L5 of the third portion 4503 is greater than the distance D5 from the connection point between the third portion 4502 and the electrode 410 to the longitudinal end of the electrode 410 (the projected length of the third portion 4503 along the width of the LED filament). When the LED filament bends, the bending of the first portion 4501 pulls on the third portion 4503. This arrangement of the third portion 4503 provides room for deformation, preventing the third portion 4503 from breaking at the connection point with the electrode 410 due to the tension of the first portion 4501.

[0202] In some embodiments, the ratio of the length L5 of the third portion 4502 to the distance D5 from the connection point between the third portion 4503 and the electrode 410 to the end of the lengthwise direction of the electrode 410 (the projected length of the third portion 4503 in the width direction of the LED filament) is greater than 1.15, 1.2, 1.3, or 1.4, thereby reducing the risk of the third portion 4503 being broken at the connection point with the electrode due to tension.

[0203] In some embodiments, the ratio of the length L5 of the third portion 4503 to the distance D5 from the connection point of the third portion 4503 with the electrode 410 to the end of the lengthwise direction of the electrode 410 (the projected length of the third portion 4503 in the widthwise direction of the LED filament) is less than 2. If the third portion 4503 is too long, the third portion 4503 will inevitably have a larger bending amplitude or occupy space in the widthwise direction of the LED filament, both of which will have an adverse effect on the LED filament (for example, a larger bending amplitude may cause greater internal stress in the third portion 4503, and occupying space in the widthwise direction of the LED filament may require a thicker light conversion layer, resulting in a thicker LED filament).

[0204] Please refer to Figures 4A and 4B to 4D. Figure 4A is a schematic diagram of an LED bulb 40h according to one embodiment of the present application. Figures 4B to 4D respectively show a side view, another side view, and a top view of the LED bulb 40h of Figure 4A. In this embodiment, as shown in Figures 4A to 4D, the LED bulb includes a lamp housing 12, a lamp base 16 connected to the lamp housing 12, at least two conductive brackets disposed within the lamp housing 12, a cantilever (not shown), a stem 19, and a single LED filament 100. The stem 19 includes opposing stem bottoms and stem tops. The stem bottom is connected to the lamp base 16, and the stem top extends into the interior of the lamp housing 12. For example, the stem top may be located approximately at the center of the interior of the lamp housing 12. The conductive brackets are connected to the stem 19. The LED filament 100 includes a filament body and two filament electrodes (or electrodes or conductive electrodes) 110 and 112, located at opposite ends of the filament body. The filament body is the rest of the LED filament 100 excluding the filament electrodes 110 and 112. The two filament electrodes 110 and 112 are connected to two conductive supports, respectively. One end of the cantilever is connected to the stem 19, and the other end is connected to the filament body.

[0205] To prevent the tungsten filament from burning in air and causing oxidation and fracture during the manufacturing process of traditional bulbs, a glass structure with a trumpet-shaped stem is designed to fit over the opening of the glass bulb housing and then sintered to seal it. A vacuum pump is then connected through the port of the trumpet stem to replace the air inside the lamp housing with nitrogen, preventing the tungsten filament from burning and oxidizing. Finally, the port of the trumpet stem is sintered to seal it. The vacuum pump then replaces the air inside the lamp housing with pure nitrogen or a combination of nitrogen and helium in an appropriate ratio through the stem, improving the thermal conductivity of the gas inside the lamp housing and removing any potential water mist. In one embodiment, the gas may be replaced with a combination of nitrogen and oxygen or nitrogen and air in an appropriate ratio, with the oxygen or air content being 1-10% of the volume of the lamp housing, preferably 1-5%. When the base layer contains saturated hydrocarbons, during the use of the LED bulb, the saturated hydrocarbons will be affected by light, heat, stress, etc. to generate free radicals. The generated free radicals or activated molecules combine with oxygen to form peroxide free radicals. Filling the lamp housing with oxygen can improve the heat resistance and light resistance of the base layer containing saturated hydrocarbons.

[0206] During the manufacturing process of an LED bulb, to increase the refractive index of the light emitted by the LED filament in the lamp housing 12, foreign matter, such as rosin, may be attached to the inner wall of the lamp housing 12. The average thickness of the foreign matter deposited per square centimeter of the inner wall area of ​​the lamp housing 12 is 0.01 to 2 mm, preferably 0.01 to 0.5 mm. In one embodiment, the foreign matter content per square centimeter of the inner wall area of ​​the lamp housing 12 accounts for 1% to 30%, preferably 1% to 10%, of the total foreign matter content of the inner wall of the lamp housing 12. This foreign matter content can be adjusted, for example, by vacuum drying the lamp housing. In another embodiment, a portion of impurities may be left in the gas filling the lamp housing 12, with the impurity content in the gas filling being 0.1% to 20%, preferably 0.1% to 5%, of the volume of the lamp housing 12. This impurity content can be adjusted, for example, by vacuum drying the lamp housing. Because the gas filling contains a small amount of impurities, the light emitted by the LED filament is reflected or refracted by the impurities, increasing the emission angle, thereby improving the luminous effect of the LED filament.

[0207] The LED bulb is located in a spatial coordinate system (X, Y, Z), where the Z axis is parallel to the stem 19. The projected lengths of the LED filament on the XY plane, YZ plane, and XZ plane are lengths L1, L2, and L3, respectively. In one embodiment, the ratio of lengths L1, L2, and L3 is 0.8:1:0.9. In another embodiment, the ratio of lengths L1, L2, and L3 is (0.5 to 0.9):1:(0.6 to 1). This ratio of lengths L1, L2, and L3 is close to 1:1:1, resulting in an excellent luminous effect and omnidirectional illumination. When bent, the LED filament 100 has at least one first bending point and at least two second bending points. The first and second bending points are spaced apart, and the height of any first bending point on the Z axis is greater than that of any second bending point. In one embodiment, the spacing between two adjacent first bending points on the Y axis or X axis is equal, resulting in a neat and beautiful appearance for the LED filament. In one embodiment, the spacing between two adjacent first bending points on the Y-axis or X-axis has a maximum value D1 and a minimum value D2, with D2 ranging from 0.5D1 to 0.9D1. This results in a relatively uniform luminous flux distribution on each plane. Assuming the diameter of the lamp base 16 is R1 (see FIG4B ), the maximum diameter of the lamp housing 12 or the maximum horizontal spacing of the lamp housing 12 in the YZ plane is R2 (see FIG4B ), and the maximum width of the LED filament 100 in the Y-axis direction on the YZ plane (see FIG4B ) or the maximum width in the X-axis direction on the XZ plane is R3 (see FIG4C ), with R3 being between R1 and R2, i.e., R1 < R3 < R2. When the LED filament is bent, the spacing between adjacent first bending points and / or adjacent second bending points in the Z-axis direction is wide, which facilitates improved heat dissipation of the LED filament. During the manufacturing process of the LED bulb, the LED filament 100 can be first placed in the inner space of the lamp housing 12 in a folded manner, and then the LED filament 100 can be manually or mechanically extended within the lamp housing 12 so that the maximum length of the LED filament 100 in the XZ plane satisfies the above relationship.

[0208] As shown in Figures 4A to 4D , in this embodiment, the LED filament 100 has one conductor segment 130, while there are two LED segments 102 and 104. Each adjacent LED segment 102 and 104 is connected by a conductor segment 130. The LED filament 100 bends in an arc at its highest point, i.e., the LED segments 102 and 104 each bend in an arc at their highest point, and the conductor segment also bends in an arc at its lowest point. The LED filament 100 can be defined as a segment following each bent conductor segment 130, with each LED segment 102 and 104 forming a corresponding segment.

[0209] Furthermore, since the LED filament 100 utilizes a flexible substrate, the flexible substrate is preferably a silicone-modified polyimide resin composition comprising a silicone-modified polyimide, a thermal curing agent, heat-dissipating particles, and a phosphor. In this embodiment, the two LED segments 102 are each bent into an inverted U-shape, with the conductor segment 130 positioned between the two LED segments 102. The degree of bending of the conductor segment 130 is equal to or greater than that of the LED segments 102. Specifically, the two LED segments 102 are bent into an inverted U-shape at the highest point of the LED filament, each having a bending radius r1. The conductor segment 130 is bent at the lowest point of the LED filament 100, each having a bending radius r2, where r1 is greater than r2. This configuration of the conductor segment 130 enables the LED filament 100 to achieve a small bending radius within a limited space. In one embodiment, the bending points of LED segments 102 and 104 are at the same height in the Z direction. Due to the symmetry of the LED filament, the LED bulb emits relatively uniform light. In another embodiment, the bending points of LED segments 102 and 104 are at different heights in the Z direction. For example, the bending point of LED segment 102 is at a greater height than the bending point of LED segment 104. When the LED filaments are of the same length and placed in the lamp housing in this manner, a portion of the LED filament is tilted toward the lamp housing, thereby improving heat dissipation. Furthermore, the vertical rod 19a of this embodiment is lower in the Z direction than the vertical rod 19a of the previous embodiment. The height of this vertical rod 19a corresponds to the height of the conductor segment 130, or the vertical rod 19a substantially contacts a portion of the conductor segment 130. For example, the lowest point of the conductor segment 130 can be connected to the top of the vertical rod 19a, thereby preventing deformation of the overall shape of the LED filament 100. In various embodiments, the conductor segments 130 may be connected to each other by passing through holes in the top of the upright 19a, or by being glued to the top of the upright 19a, but the present invention is not limited thereto. In one embodiment, the conductor segments 130 and the upright 19a may be connected using a guide wire, for example, by extending a guide wire from the top of the upright 19a to connect the conductor segments 130.

[0210] As shown in FIG4B , in this embodiment, the conductor segment 130 is taller than the two electrodes 110 and 112 in the Z direction. The two LED segments 102 and 104 extend upward from the two electrodes 110 and 112 to their highest points, then bend downward and extend to the conductor segment 130 connecting the two LED segments 102 and 104. As shown in FIG4C , in this embodiment, the profile of the LED filament 100 in the XZ plane resembles a V-shape. Specifically, the two LED segments 102 extend upward and outward, bend at their highest points, and then extend downward and inward to the conductor segment 130. As shown in FIG4D , in this embodiment, the profile of the LED filament 100 in the XY plane has an S-shape. As shown in FIG4B and FIG4D , in this embodiment, the conductor segment 130 is located between the electrodes 110 and 112. As shown in FIG4D , in this embodiment, on the XY plane, the bending point of the LED segment 102, the bending point of the LED segment 104, and the electrodes 110 and 112 are approximately located on a circle centered on the conductor segment 130 (or the stem 19 or the upright 19 a ). For example, on the XY plane, the bending point of the LED segment 102, the bending point of the LED segment 104 are located on the same circle centered on the stem 19 or the upright 19 a . In some embodiments, on the XY plane, the bending point of the LED segment 102, the bending point of the LED segment 104, and the electrodes 110 and 112 are located on the same circle centered on the stem 19 or the upright 19 a .

[0211] Please refer to FIG5 , which is a schematic diagram of an LED bulb 40i according to an embodiment of the present application. The LED bulb 40i of this embodiment has the same basic structure as the LED bulb 40h of FIG4 , including a lamp housing 12, a lamp base 16 connected to the lamp housing 12, at least two conductive brackets provided in the lamp housing 12, a cantilever (not shown), a stem 19, and a single LED filament 100. The difference is that the LED bulb 40i of this embodiment does not have a vertical rod 19a, and the stem 19 includes an inflatable tube. The gas in the lamp housing 12 is passed through the inflatable tube. The gas tube is filled, as shown in FIG5 . In the Z-axis direction, the shortest distance from the LED filament 100 (or the bending point of the LED segment 102 / 104 ) to the lamp housing 12 is H1, and the shortest distance from the conductor segment 130 of the LED filament 100 to the stem 19 is H2. H1 is less than or equal to H2. The bending point of the LED segment is closer to the lamp housing, so the heat dissipation path of the LED filament is short, thereby improving the heat dissipation effect of the bulb. In other embodiments, H1 is greater than H2, so that the LED filament is roughly located in the middle area of ​​the lamp housing, and the lighting effect is better.

[0212] Referring to FIG6 , FIG6 is a schematic diagram of the structure of a lamp holder according to an embodiment of the present application. In this embodiment, a power supply assembly (or driving power supply) 20 is provided in the lamp holder 16. The power supply assembly is electrically connected to the LED filament and the electrodes of the LED filament. The power supply assembly 20 includes a substrate 201. The substrate 201 is provided with a heating element (an element that generates a lot of heat during operation, such as an IC, a resistor, etc.) and a heat-sensitive element (such as an electrolytic capacitor, etc.). The lamp holder 16 has an inner surface and an outer surface opposite to the inner surface. The outer surface of the lamp holder 16 is away from the power supply assembly 20. The heating element is closer to the inner surface of the lamp holder 16 than the heat-sensitive element. The heating element has an insulating sheet 202 on it. The insulating sheet 202 contacts the inner surface of the lamp holder 16. For example, the insulating sheet 202 can be brought into contact with the inner surface of the lamp holder 16 by welding or fasteners. In one embodiment, the heating element is packaged as a whole into a component, and the component has a heat sink, which contacts the inner surface of the lamp holder 16. For example, after the IC and the rectifier bridge are packaged into a component, the heat sink is made to contact the inner surface of the lamp holder 16 by welding or fasteners. The heat sink can be welded to the inner surface of the lamp holder 16 as a negative wire.

[0213] In another embodiment, the substrate 201 is in direct contact with the inner surface of the lamp holder 16. Compared with indirect contact between the substrate and the lamp holder through glue, the direct contact method can improve the heat dissipation effect of the bulb lamp while reducing the heat transfer medium.

[0214] In another embodiment, the heating element is covered with thermal conductive adhesive. For example, the substrate 201 has a first surface 2011 and a second surface 2012, the second surface 2012 is away from the LED filament, the heating element and the heat-sensitive element are respectively located on the first surface 2011 and the second surface 2012, and the thermal conductive adhesive is covered on the first surface 2011. The heat generated by the heating element can be transferred to the lamp holder through the thermal conductive adhesive, thereby improving the heat dissipation effect of the bulb.

[0215] In another embodiment, as shown in FIG7 , a heat conducting portion 203 is provided on the inner surface of the lamp holder 16. The heat conducting portion 203 may be a net bag for accommodating the heating element or a metal part in contact with the heating element. The thermal conductivity of the heat conducting portion 203 is greater than or equal to the thermal conductivity of the lamp holder 16. The heat generated by the heating element can be quickly transferred to the lamp holder 16 through the heat conducting portion 203, thereby improving the heat dissipation effect of the bulb lamp.

[0216] In another embodiment, each surface of the power supply assembly 20 is covered with thermally conductive adhesive, with a portion of the thermally conductive adhesive contacting the inner surface of the lamp holder 16. This can be achieved, for example, by using a flexible substrate that is entirely incorporated into the lamp holder 16, which is then filled with thermally conductive adhesive. Covering the entire power supply assembly with thermally conductive adhesive increases the heat dissipation area, thereby significantly improving heat dissipation.

[0217] In another embodiment, as shown in FIG7C , the substrate 201 is parallel to the axial direction of the lamp holder 16 (or the axial direction of the stem 19 in FIG4 , FIG5 , and FIG8 ). Since all the heating elements can be placed on the side of the substrate closest to the lamp holder, the heat generated by the heating elements can be quickly transferred to the lamp holder, thereby improving the heat dissipation efficiency of the power supply assembly. In addition, the heat-sensitive elements and the heat-resistant elements can be placed on different surfaces of the substrate, reducing the impact of the heat generated by the heating elements during operation on the heat-sensitive elements, thereby improving the overall reliability and life of the power supply module. In one embodiment, the substrate 201 is provided with heating elements (elements that generate a lot of heat during operation, such as ICs, resistors, etc.) and heat-sensitive elements (such as electrolytic capacitors, etc.). The heating elements are closer to the inner surface of the lamp holder 16 than other electronic components (such as heat-sensitive elements or other non-heat-sensitive components, such as capacitors). Therefore, the heating elements have a shorter heat transfer distance to the lamp holder 16 than other electronic components, which is more conducive to the heat generated by the heating elements during operation being transferred to the lamp holder 16 for dissipation, thereby improving the heat dissipation efficiency of the power supply assembly 20.

[0218] As shown in Figures 5 to 7, the projections of the gas tube and the substrate 201 on the XY plane overlap. In some embodiments, the projections of the gas tube and the substrate 201 on the XZ and / or YZ planes are spaced apart (or do not overlap), or in the height direction of the lamp holder (Z-axis direction), there is a certain distance between the gas tube and the substrate, and the gas tube and the substrate do not contact each other, thereby increasing the accommodation space of the power supply component and improving the utilization rate of the substrate. In addition, when the substrate 201 contacts the inner surface of the lamp holder 16, a cavity is formed between the first surface 2011 of the substrate 201 and the core column 19. The heat generated by the heating element on the first surface of the substrate can be transferred through the cavity, reducing the thermal impact on the heat-sensitive elements on the second surface, thereby improving the service life of the power supply component.

[0219] Please refer to Figures 8A to 8D , which illustrate schematic diagrams of an LED bulb 40j according to an embodiment of the present application. This embodiment of LED bulb 40j shares the same basic structure as LED bulb 40h in Figure 4 , including a lamp housing 12, a lamp base 16 connected to lamp housing 12, at least two conductive brackets disposed within lamp housing 12, at least one cantilever 15, a stem 19, and an LED filament 100. The cantilever 15 is not shown in Figures 8B and 8C . The stem 19 includes a stem 19a. Each cantilever 15 includes opposing first and second ends. The first end of each cantilever 15 is connected to the stem 19a, while the second end of each cantilever 15 is connected to the LED filament 100. The LED bulb shown in Figure 8C differs from the bulb shown in Figure 4 in that, in the Z-axis direction, the height of stem 19a is greater than the distance between its bottom and the conductor segment 130. Stem 19a includes opposing bottom and top ends, with the bottom end being closer to the gas tube. As shown in Figure 8D , on the XY plane, the arcs corresponding to at least two bend points of the LED filament are centered at angles ranging from 170° to 220°, ensuring appropriate spacing between the bend points of the LED segments and ensuring effective heat dissipation. At least one cantilever 15 is located at a bend point of the LED filament 100, for example, at the bend point of LED segments 102 / 104. Each cantilever 15 intersects with the LED filament 100. On the XY plane, at least two of these intersections lie on a circle centered on the stem 19 (or upright 19a). This creates a certain degree of symmetry in the LED filament, resulting in approximately equal luminous flux in all directions and uniform illumination from the LED bulb. In one embodiment, a line connecting at least one intersection point and the bending point of the conductor segment 130 forms a straight line La. The intersection point on line La forms a straight line Lb with the electrodes 110 / 112 of the LED filament. The angle α between lines La and Lb is in the range of 0°<α<90°, preferably 0°<α<60°. This ensures that the bent LED segments have an appropriate spacing, resulting in better light extraction and heat dissipation. The bending points of the LED segments have a curvature radius. For example, the bending point of LED segment 102 has a curvature radius r3, and the bending point of LED segment 104 has a curvature radius r4. r3 is equal to r4, ensuring uniform light extraction across all planes. Alternatively, r3 can be set to be greater than r4 or less than r4 to meet lighting and / or heat dissipation requirements in specific directions. The bending point of the conductor segment 130 has a curvature radius r5, which is smaller than the maximum value of r3 and r4, that is, r5<max(r3, r4). Therefore, the LED filament is less likely to break. In addition, there is a certain distance between the LED segments closer to the core to prevent the heat generated by the two LED segments from affecting each other.

[0220] In one embodiment, an LED filament includes a top layer and a supporting layer. When the LED filament is bent, in any cross-section along the height of the LED filament or along the central axis (or optical axis) of the LED chip, the supporting layer is closer to the lamp housing than the top layer. In other words, the shortest distance from the supporting layer to the lamp housing is shorter than the shortest distance from the top layer to the lamp housing. In some embodiments, the LED filament, when bent, has a bending point (or bending zone), at which the radius of curvature of the supporting layer is greater than the radius of curvature of the top layer. In some embodiments, when the LED filament is bent, in any cross-section along the height of the LED filament or along the central axis (or optical axis) of the LED chip, the top layer is closer to the central axis (or stem) of the LED bulb than the supporting layer, and the distance from the top layer to the central axis (or stem) of the LED bulb is shorter than the distance from the supporting layer to the central axis (or stem) of the LED bulb. In some embodiments, the LED filament, when bent, has a bending point (or bending zone), at which the light-emitting surface of the LED chip faces the central axis (or stem) of the LED bulb. With the above design, when any LED filament in an LED bulb bends, the bending stress on the conductors in the LED filament is reduced, making it less likely to break. LED segments 102 / 104 include a first segment and a second segment. The first segment extends upward (toward the top of the lamp housing) from electrodes 110 / 112 to the bending point, and the second segment extends downward (toward the lamp base) from the bending point to conductor segment 130 connecting the two LED segments 102 and 104. The first and second segments are spaced apart from the lamp housing 12 by first and second distances, respectively. The first distance is less than the second distance. In the direction of the first distance, the base layer 420b of the LED filament is closer to the lamp housing 12, while the top layer 420a of the LED filament is farther away. For example, in FIG8B , the first segment of LED segment 104 is spaced apart from the lamp housing 12 by first and second distances D1 and D2, respectively. The first distance D1 is less than the second distance D2. In the direction of the first distance D1, the base layer 420b of the LED filament is closer to the lamp housing 12, while the top layer 420a of the LED filament is farther away. When the LED filament is bent, the wire in the LED filament is subjected to less bending stress and is less likely to break, thereby improving the production quality of the LED bulb.

[0221] 4A to 4D and 8A to 8D, the lamp housing 12 is divided into an upper portion and a lower portion by a plane A. The lamp housing 12 has a maximum width at plane A. For example, the plane figure formed by R2 (maximum horizontal spacing) in FIG. 4B is located on plane A. When the stem 19 intersects with plane A, the lamp housing 12 has a top and a bottom relative to each other. The bottom of the lamp housing is close to the lamp head 16. The length of the LED filament between the top of the lamp housing and plane A (or the distance from the highest point of the LED filament to plane A in the height direction of the LED bulb) is smaller than the length of the LED filament between plane A and the bottom of the lamp housing (or the distance from the lowest point of the LED filament to plane A in the height direction of the LED bulb). Because the inner diameter of the lamp housing 12 above the top of the stem 19 is smaller when the stem 19 intersects with plane A, the lamp housing 12 accommodates The gas volume is small. If most of the LED filaments are located at the top of the core column, it will affect the overall heat dissipation effect of the LED filament, and thus reduce the product quality; if the core column 19 has a certain distance from plane A and the distance from the top of the core column to plane A is less than the height of the vertical pole 19a, the core column 19 includes a relative core column bottom and a core column top, the core column bottom is connected to the lamp head 16, and the core column top extends toward the top of the lamp shell. The length of the LED filament between the top of the core column and the top of the lamp shell (or the distance between the highest point of the LED filament and the top of the core column) is less than the length of the LED filament between the top of the core column and the bottom of the lamp shell (or the distance between the top of the core column and the lowest point of the LED filament). Most of the LED filaments can be indirectly supported by the core column, thereby ensuring the stability of the LED filament shape during transportation of the LED bulb. In some embodiments, when there is a distance between the core column 19 and plane A and the distance from the top of the core column to plane A is greater than the height of the vertical pole 19a, the core column 19 includes a relative core column bottom and a core column top, the core column bottom is connected to the lamp head 16, and the core column top extends toward the top of the lamp housing. The length of the LED filament located between the top of the core column and the top of the lamp housing is greater than the length of the LED filament located between the top of the core column and the bottom of the lamp housing. Since the volume of gas contained between the top of the core column and the bottom of the lamp housing is large, and most of the LED filaments are located between the top of the core column and the bottom of the lamp housing, it is beneficial to dissipate heat for the LED filament.

[0222] Please refer to Figures 9A to 9D, which are schematic diagrams of an LED bulb according to an embodiment of the present application. The LED bulb includes a lamp housing 12 and a lamp base 16 connected to the lamp housing 12. Multiple LED filaments C1, C2, C3, ..., Cn are disposed within the lamp housing 12, where n is an integer. Each LED filament 100 includes a first electrode and a second electrode. After the LED filament is bent, the vertical distance between the first and second electrodes does not exceed the height of the stem 19. In one embodiment, when the LED filament 100 is unbent, it includes a first end and a second end that are opposite each other. These first and second ends are used to connect to a power supply assembly (not shown) to power the LED chips on the LED filament 100. The length of the LED filament 100 is the distance from the first end to the second end. When the LED filament 100 is bent, the first and second ends of each LED filament 100 are separated from each other, resulting in a spatial distribution of each LED filament 100. In some embodiments, along the central axis of the LED bulb, the vertical distance between the first end of any LED filament and the first end of any other LED filament is no more than 2 cm, or / and the vertical distance between the second end of any LED filament and the second end of any other LED filament is no more than 2 cm. This allows the first electrodes of the multiple LED filaments to pass through (or substantially pass through) the first plane, and the second electrodes of the multiple LED filaments to pass through (or substantially pass through) the second plane. When the LED filaments are electrically connected, the first ends of the multiple LED filaments 100 are connected together, or the second ends are connected together, or the first end of one LED filament 100 is connected to the second end of another LED filament, simplifying the electrical connection. Compared to the second plane, the first plane is closer to the top of the lamp housing, and the first and second planes are separated. The first and second planes are parallel to each other, or may be at a certain angle to each other.

[0223] Each LED filament 100 is arranged in a spiral shape, extending in a spiral about an axis (e.g., the central axis of an LED bulb). The angle of rotation of the second end of the LED filament relative to the first end about the central axis of the LED bulb exceeds 270 degrees (when the LED filament is projected onto a plane along the central axis of the LED bulb, the central angle occupied by the LED filament 100 on the plane is greater than 270 degrees). Preferably, the axes around which at least two LED filaments 100 rotate coincide with each other, or the axes around which at least two LED filaments 100 rotate are parallel to each other or at an angle. The axis around which the LED filament 100 extends between the first and second ends forms a smooth curve, or a broken line. In one embodiment, the axis around which the LED filament 100 rotates is parallel to the stem 19, or the LED filament 100 extends in a spiral about the stem 19.

[0224] The distance between at least one point on LED filament C1 and stem 19 is equal to or approximately equal to the distance between a point on LED filament Cn (n≠1) and stem 19. In one embodiment, along the height of the LED bulb, LED filaments C1, C2, C3, ..., Cn are sequentially adjacent, and the distance between LED filament C1 and LED filament C2 is equal to or approximately equal to the distance between LED filament Cn and LED filament Cn+1 (n≥2). In the xy plane, the first and / or second electrodes of LED filaments C1, C2, C3, ..., Cn are located on a circle centered on stem 19 (or the vertical rod). In the XZ or YZ plane, the projections of the LED filaments intersect, with the projections of some LED filaments Cn intersecting with the projections of LED filament Cn+1 (n≥1). In some embodiments, the projection of one LED filament intersects with the projections of other LED filaments on the XZ plane or the YZ plane. For example, in an LED bulb including four LED filaments C1, C2, C3, and C4, the projection of a portion of LED filament C2 intersects with the projections of LED filament C1, LED filament C3, and LED filament C4 on the XZ plane or the YZ plane. Of course, in other embodiments, the projection of a portion of LED filament C2 may intersect with the projections of at least two of LED filaments C1, C3, and C4.

[0225] 10A and 10B , a fixing portion 13 is provided within the lamp housing 12 . A power module (not shown) is connected to the fixing portion 131 . The fixing portion 13 has a first opening 133 . The main body of each filament is located within the first opening 133 . A portion of the electrodes 410 / 412 of each LED filament is connected to the fixing portion 131 to secure the position of the LED filament 100 . Specifically, the fixing portion 13 has a first connection portion 131 and a second connection portion 132 relative to each other, the first electrode 410 is connected to the first connection portion 131, and the second electrode 412 is connected to the second connection portion 132. The first connection portion 131 has a first end and a second end relative to each other, and the second connection portion 132 has a third end and a fourth end relative to each other. Compared with the second end, the first end of the first connection portion 131 is close to the third end of the second connection portion 132. When the fixing portion 13 is curled, the first end of the first connection portion 131 approaches the second end of the first connection portion 131, and the third end of the second connection portion 132 approaches the fourth end of the second connection portion 132, that is, the first connection portion 131 and the second connection portion 132 curl in the same direction, and the LED filament 100 is in a straight strip shape. In some embodiments, when the fixing portion 13 is curled, the first end of the first connecting portion 131 approaches the second end of the first connecting portion 131, and the fourth end of the second connecting portion 132 approaches the third end of the second connecting portion 132. In other words, the first connecting portion 131 and the second connecting portion 132 curl in opposite directions, resulting in a bent LED filament 100. After the fixing portion 13 is curled, the power module is electrically connected to the first connecting portion 131 and the second connecting portion 132, respectively. A carrier 14 is also provided within the lamp housing 12. After the fixing portion 13 is curled, the LED filament 100 is attached to the carrier 14. The carrier 14 is made of a material with a light transmittance of at least 70%, such as glass, to reduce absorption of light emitted by the LED filament 100 by the carrier 14. In other embodiments, the carrier can be cylindrical, with the LED filament secured to the carrier by adhesive or other means.

[0226] Referring to Figures 11A and 11B , a support unit is provided on the stem 19 . The support unit is perpendicular to the stem 19 (or the central axis of the LED bulb) and extends along the central axis of the LED bulb toward the top of the lamp housing 12 . The support unit is provided with a plurality of support portions 15 , each of which is provided with a second opening 151 . The height of the LED filament 100 is smaller than the width of the LED filament 100 . The LED filament 100 can first enter the support portion 15 at an angle through the second opening 151 . Since the minimum distance of the second opening 151 is greater than the width of the LED filament 100 , the LED filament 100 can be prevented from escaping from the support portion 15 , thereby fixing the shape of the LED filament 100 .

[0227] Please refer to Figure 12, which is a schematic diagram of the light spectrum of an LED bulb according to one embodiment of the present application. In this embodiment, the LED bulb can be any of the LED bulbs disclosed in the previous embodiments, and any single LED filament disclosed in the previous embodiments is provided within the LED bulb. Measuring the light emitted by the LED bulb using a spectrum meter yields the spectrum diagram shown in Figure 12. This spectrum diagram shows that the LED bulb's spectrum is primarily distributed between wavelengths of 400nm and 800nm, with three peaks, P1, P2, and P3, appearing at three locations within this range. Peak P1 occurs between approximately 430nm and 480nm, peak P2 between approximately 580nm and 620nm, and peak P3 between approximately 680nm and 750nm. Peak P1 is less intense than peak P2, and peak P2 is less intense than peak P3. As shown in Figure 12, this spectral distribution is close to that of a traditional incandescent filament lamp and also close to that of natural light. In one embodiment, a schematic diagram of the light spectrum of a single LED filament is shown in Figure 13. This spectral diagram shows that the spectrum of the LED bulb is primarily distributed between 400nm and 800nm, with three peaks, P1, P2, and P3, appearing at three locations within this range. Peak P1 is approximately between 430nm and 480nm, peak P2 is approximately between 480nm and 530nm, and peak P3 is approximately between 630nm and 680nm. In terms of intensity, the intensity of peak P1 is less than that of peak P2, and the intensity of peak P2 is less than that of peak P3. As shown in Figure 13, this spectral distribution is close to that of a traditional incandescent filament lamp and also close to that of natural light.

[0228] Please refer to Figure 14, which shows the light spectrum of an LED bulb according to one embodiment of the present application. As can be seen from the figure, the LED bulb's spectrum distribution has three peaks, P1', P2', and P3', similar to those shown in Figure 13, between wavelengths of 400nm and 800nm. Peak P1' occurs between approximately 430nm and 480nm, peak P2' occurs between approximately 480nm and 530nm, and peak P3' occurs between approximately 630nm and 680nm. Peak P1' is less intense than peak P2', while peak P2 is less intense than peak P3'. The differences are that P1' has a greater intensity than P1, and P3' has a greater half-wavelength width than P3. This LED bulb has an average color rendering index (Ra) (R1-R8) greater than 95, a saturated red color (R9) greater than or equal to 90, and an LED filament luminous efficacy (Eff) greater than or equal to 100 lm / w.

[0229] Figures 17-20 show light distribution curves for LED bulbs according to various embodiments. In conjunction with Figure 15 , the figures show that the light emitted by the LED bulb is roughly symmetrically distributed around the optical axis L. When the LED bulb is illuminated, the light emitted exhibits a butterfly-shaped light distribution curve, exhibiting a relatively wide light distribution. If the lamp base is facing upward and the lamp housing is facing downward (as shown in Figure 16 ), the downward direction is defined as 0 degrees. Curve L1 shows the light intensity distribution curve for the 0-degree and 180-degree sections (C0 / 180), while curve L2 shows the light intensity distribution curve for the 90-degree and 270-degree sections (C90 / 270). C0 / 180 and C90 / 270 are symmetrical about the central axis of the LED bulb, respectively. The LED bulb has symmetrical light distribution at the 0-degree and 180-degree sections and / or at the 90-degree and 270-degree sections. Because when the LED bulb is lit, the filament lengths or the number of LED chips on the two cross-sections are different in different angle ranges, the luminous intensity on curve L1 is greater than the light intensity on curve L2 in some angle ranges, while the luminous intensity on curve L1 is less than the light intensity on curve L2 in other angle ranges. As a result, curves L1 and L2 partially overlap, that is, there is at least one point on curve L1 that is located on curve L2.

[0230] Specifically, in the 0-degree and 180-degree cross-sections, and the 90-degree and 270-degree cross-sections, within a certain angular range, the luminous intensity of curve L1 is greater than that of curve L2 (i.e., curve L1 is outside curve L2). Within this angular range, the length of the LED filament corresponding to curve L1 is greater than that corresponding to curve L2, or the number of LED chips corresponding to curve L1 is greater than that corresponding to curve L2. For example, this occurs within the range of 100 to 130 degrees in FIG. 17 , within the range of 30 to 80 degrees in FIG. 18 , within the range of 30 to 160 degrees in FIG. 19 , and within the range of 70 to 80 degrees in FIG. 20 .

[0231] On a plane symmetrically centered around the central axis of the LED bulb, a portion of the top layer of the LED filament faces outward, while a portion of the support layer faces outward. On a cross-section of the central axis (or optical axis) of the LED chip, when the support layer faces outward, the shortest distance from the support layer to the lamp housing is less than the shortest distance from the top layer to the lamp housing; when the top layer faces outward, the shortest distance from the top layer to the lamp housing is less than the shortest distance from the support layer to the lamp housing. Light emitted by the LED filament partially originates from the top layer and partially from the support layer. The luminous flux of light emitted through the top layer is greater than the luminous flux of light emitted through the support layer. Planes symmetrically centered around the central axis of the LED bulb (e.g., the YZ plane) contain both light emitted from the top layer and from the base layer. If some of these planes only receive light from the top layer or the base layer, the light distribution of the LED bulb will be uneven, affecting the light output of the LED bulb.

[0232] In one embodiment, when any LED filament in an LED bulb is bent, at least two LED chips in one LED filament emit light in different directions. If the LED bulb contains more than two LED filaments, the light emission direction of at least one LED chip in one LED filament is different from the light emission direction of at least one LED chip in another LED filament. The light emission direction of the LED chips will affect the luminous flux of the LED bulb at different angles. Since the multiple LED chips in the LED filament have different light emission directions, the LED bulb will emit light at multiple angles, preventing dark areas from appearing at certain angles. For example, in Figures 14 to 17, the LED bulb emits light in all areas except near the lamp base.

[0233] In one embodiment, some LED bulbs have a relatively low luminous flux distribution within the range of 0 to 30 degrees. For example, the total luminous flux within the range of 0 to 30 degrees is 3% to 20% of the total luminous flux of the LED bulb. When the LED filament in these LED bulbs is bent around the central axis of the LED bulb, the LED filament is relatively far from the central axis (or stem) of the LED bulb, resulting in less light output from the central axis region of the LED bulb. In some embodiments, different regions of the LED filament have different distances from the central axis (or stem) of the LED bulb. Some of the LED filament is close to the central axis (or stem) of the LED bulb, while others are far from the central axis. Furthermore, some LED chips are close to the central axis (or stem) of the LED bulb, while others are far from the central axis. If a portion of the LED filament is relatively close to the central axis of the LED bulb, the distance between this portion of the LED filament (the top layer or the supporting layer) and the central axis (or stem) of the LED bulb is 2-15 mm, or the cantilever length is 2-15 mm. On the one hand, the heat generated by the LED filament is not easy to accumulate; on the other hand, the luminous flux in the light emission direction of the LED bulb is increased, so that the spatial distribution of the output light of the LED bulb is uniform.

[0234] In some embodiments, at least a portion of the LED filament intersects the central axis (or stem) of the LED bulb. For example, this intersection can occur when a portion of the LED filament passes through the top of the stem, or when a portion of the LED filament is approximately zero distance from the stem (0-5 mm). Alternatively, the LED filament and stem can be considered as separate lines that intersect or intersect with the central axis of the LED bulb. The LED filament increases the luminous flux in the central axis region of the LED bulb, with the luminous flux within the range of 0 to 30 degrees being 20 to 50% of the total luminous flux of the LED bulb, thereby preventing the formation of a dark area in the light emission direction of the central axis of the LED bulb. Furthermore, the portion of the LED filament that intersects the central axis (or stem) of the LED bulb includes at least one LED chip, thereby increasing the luminous flux in the central axis region of the LED bulb.

[0235] In some embodiments, the LED filaments in the LED bulb are symmetrical about the central axis (or stem) of the LED bulb in at least one plane (e.g., the XY plane, the YZ plane, or the YZ plane). Furthermore, in at least one plane, the length of the LED filaments is symmetrical about the central axis (or stem) of the LED bulb. Still further, in at least one plane, the number of LED chips in the LED filaments is symmetrical about the central axis (or stem) of the LED bulb. When the LED filaments are symmetrically distributed, the light intensity distribution of the LED bulb is relatively uniform on the 0-degree and 180-degree cross-sections and the 90-degree and 270-degree cross-sections. The areas enclosed by curves L1 and L2 are substantially the same. For example, as shown in Figures 17-18, the light distribution of the LED bulb is relatively uniform.

[0236] The beam angle of an LED bulb at 0° and 180° sections is α, and the beam angle of an LED bulb at 90° and 270° sections is β. The absolute difference between α and β is less than 50°. If the difference between α and β is large, the locations of maximum light intensity on the two sections of the LED bulb will be far apart, resulting in more pronounced light levels and poor light uniformity. Furthermore, if the absolute difference between α and β is less than 30°, the LED bulb has excellent light uniformity. Furthermore, if the absolute difference between α and β is less than 10°, the light distribution of the LED bulb is uniform. The definition of beam angle can be determined by the International Commission on Illumination (CIE Europe) or the International Society for Illumination (IES USA). Specifically, according to the International Society for Illumination (IES USA), the average beam angle (the average of α and β) of an LED bulb is greater than 100°, indicating a wide light distribution. In this embodiment, the beam angle of an LED bulb is defined as the angle between the two sides at 50% of the normal light intensity.

[0237] The distance between the highest and lowest points of the LED filament in an LED bulb accounts for 50% to 80% of the housing height (the distance from the connection between the housing and the base to the top of the housing). This allows light to pass through most of the housing, resulting in a wide light distribution. If the LED bulb includes multiple LED filaments, the highest and lowest points of the LED filaments described above refer to the highest and lowest points of any single LED filament.

[0238] Figure 21 is a circuit diagram of a constant current circuit according to an embodiment of the present invention. Following common circuit diagram conventions, the optional parameters of each component are indicated in international standard units. In the following description, for simplicity, the first resistor R1 is referred to as R1, and the other components are similarly referred to.

[0239] According to the circuit shown in Figure 21, after power-on, the voltage at point A is equal to the voltage divided by R4 across R3 and R4. Therefore, the current between the drain and source of M1 increases, increasing Vbe sufficiently to turn on Q1, which in turn lowers the voltage at point A, causing the current between the drain and source of M1 to decrease. Because R1 is very small, Vbe cannot reach Q1's turn-on voltage, causing Q1 to turn off. When Q1 turns off, the voltage at point A returns to the voltage divided by R4 across R3 and R4, causing the current between the drain and source of M1 to increase again. This process then repeats, ultimately keeping M1 on and maintaining the current IR1 flowing through R1 at approximately the ratio of Vbe to R1. This ensures a constant current through load D5.

[0240] The structure of the circuit shown in Figure 22 is basically the same as that of Figure 21, except that Figure 22 includes a positive temperature coefficient thermistor (PTC). The figure shows the voltages at some points and the currents in some branches. The current flowing through the PTC is IPTC = (Vin-Vbe) / PTC. Since the current at the base of input Q1 is almost zero, IPTC = IR2, and IR2 = (Vbe-VB) / R2, where VB represents the voltage at point B. Therefore, (Vin-Vbe) / PTC = (Vbe-VB) / R2, where PTC represents the resistance of the PTC resistor. According to this transformation, VB = Vbe-(Vin-Vbe)R2 / PTC. From Figure 22, we can see that VB = ID5 × R1, so ID5 × R1 = Vbe-(Vin-Vbe)R2 / PTC, which gives Formula 1:

[0241] ID5=Vbe / R1-[(Vin-Vbe)×R2] / (PTC×R1).

[0242] Equation 1 shows that the load current ID5 is also affected by the PTC resistance. Due to the physical properties of transistors, their base voltage Vbe decreases as temperature rises. Equation 1 shows that a decrease in Vbe decreases ID5, which in turn reduces the load current, affecting the lamp's illumination. Conversely, the PTC resistance increases as temperature rises. Equation 1 shows that an increase in PTC resistance also increases ID5, helping to offset the fluctuations in load current caused by the decrease in Vbe.

[0243] According to Formula 1, if the PTC resistor is replaced with a negative temperature coefficient thermistor, ID5 will increase as the temperature drops, thus achieving low-temperature protection for the lamp. Formula 1 also shows that R1 directly affects ID5, meaning R1 directly affects the lamp's brightness. Therefore, while the power supply voltage remains constant, the load current can be adjusted by selecting the value of R1.

[0244] According to the circuits shown in Figures 21 and 22, M1 acts as the main switching element, and its current is affected by the negative feedback loop formed by R1, R2, and Q1. Q1, as the secondary switching element, is turned on or off by the current of M1, ultimately maintaining the on-current of M1 at a fixed level, thereby realizing a constant current circuit for the load. Figures 21 and 22 are only examples, and other circuit topologies may also be used, such as Figure 23, which is a circuit diagram of a third constant current circuit according to an embodiment of the present invention.

[0245] According to the circuit shown in FIG23 , in a preferred manner, that is, when PTC1 (or an NTC resistor) is added, similar to the analysis above, after power-on, the on-current of M1 increases, causing Q3 to turn on, and the turning on of Q3 causes the on-current of M1 to decrease, which also constitutes a negative feedback similar to that in FIG24 and FIG22 , so that M1 maintains a constant on-current state, and the current flowing through the load D1 is constant.

[0246] In the technical solutions of the embodiments of the present invention, the switching elements may also employ other types of switching devices. In addition to being a DC voltage source, the power supply may also be a rectifier circuit, thereby converting the external AC input (usually mains power) into DC. Furthermore, the fourth resistor R4 may be connected in parallel with a capacitor, so that the voltage at point A gradually increases upon power-up, thereby achieving a delayed power-up function.

[0247] According to the technical solution of the embodiments of the present invention, a main switching element and a negative feedback circuit are used to maintain a constant current through the main switching element, thereby realizing a constant current circuit. This approach requires only a small number of discrete components to implement a constant current circuit and does not involve electromagnetic compatibility issues. In the specific circuit structure, a PTC or NTC can also be used to mitigate temperature drift. When applied to a lamp, this constant current circuit occupies a small space and provides stable light emission.

[0248] Reference Figure 24 is a circuit block diagram of an LED lamp according to an embodiment of the present application. In this embodiment, the LED lamp includes a constant current drive circuit 10a, a shunt circuit 20a, and an LED module 30a. The constant current drive circuit 10a is a constant current source that provides a constant current. The LED module 30a includes an LED component 31a and an LED component 32a. The LED components 31a and 32a are electrically connected to the shunt circuit 20a. The shunt circuit 20a is used to receive the constant current from the constant current drive circuit 10a and distribute the current to the LED components 31a and 32a. In this embodiment, the LED component is a light-emitting diode or multiple light-emitting diodes connected in series.

[0249] In some embodiments, LED component 31a and LED component 32a are configured with different color temperatures. The brightness of LED components 31a and 32a can be adjusted by adjusting the current flowing through LED component 31a and LED component 32a. The color temperature can be adjusted by adjusting the brightness ratio of LED component 31a and LED component 32a.

[0250] In some embodiments, LED assembly 31a and LED assembly 32a are configured as different colors.

[0251] In some embodiments, LED assembly 31 a and LED assembly 32 a include different numbers of light-emitting diodes.

[0252] Through the configuration of the above embodiment, only one constant current drive circuit is required to control at least two LED assemblies, achieving the function of adjusting color temperature or color. In particular, when the number of light-emitting diodes included in the LED assemblies varies, current regulation of different LED assemblies can still be achieved.

[0253] Reference Figure 25A is a schematic diagram of the circuit structure of an LED lamp according to an embodiment of the present application. In this embodiment, a constant current drive circuit 10a includes a constant current source A1, an LED assembly 31a includes an assembly D1, an LED assembly 32a includes an LED assembly D2, and a shunt circuit 20a includes a transistor Q1, resistors R1, and R2. The anode of LED assembly D1 is electrically connected to the anode of LED assembly D2 and is also electrically connected to the first output terminal of constant current source A1. The cathode of LED assembly D1 is electrically connected to the collector of transistor Q1, the emitter of transistor Q1 is electrically connected to a common ground terminal, the base of transistor Q1 is electrically connected to the first pin of resistor R2, and the second pin of resistor R2 is electrically connected to the first pin of resistor R1 and the cathode of LED assembly D2. The second pin of resistor R1 is electrically connected to the common ground terminal. The second output terminal of constant current source A1 is electrically connected to the common ground terminal.

[0254] In this embodiment, the LED components D1 and D2 include one light emitting diode or a plurality of light emitting diodes connected in series (ie, the LED chips in the aforementioned embodiment).

[0255] The operating principle of shunt circuit 20a is explained below. In this embodiment, constant current source A1 provides a constant current I1. After being shunted by shunt circuit 20a, the current flowing through LED component D1 is ID1, and the current flowing through LED component D2 is ID2. The current flowing through resistor R1 is IR1, and the current flowing through resistor R2 is IR2. The voltage at the base of transistor Q1 is Vbe, and the current at the emitter of transistor Q1 is IQ1. These currents satisfy the following relationship:

[0256] I1=ID1+ID2

[0257] ID2=IR1+IR2

[0258] IQ1=ID1+IR2

[0259] In this embodiment, since the current of IR2 is small and can be ignored,

[0260] ID2≈IR1

[0261] IQ1≈ID1

[0262] IR1≈Vbe / R1

[0263] When ID2 is increasing, VR1 increases, and IR2 increases. According to the transistor's amplification principle, ID1 increases because ID1 and ID2 add up to a constant value, I1. When ID1 increases, ID2 decreases. Therefore, when ID2 is increasing, the regulation of shunt circuit 20a suppresses the increase in ID2, allowing ID2 to stabilize. Similarly, when ID2 is decreasing, VR1 decreases, and IR2 decreases. According to the transistor's amplification principle, ID1 decreases because ID1 + ID2 = I1. Therefore, when ID1 decreases, ID2 increases. Therefore, when ID2 is decreasing, the regulation of shunt circuit 20a suppresses the decrease in ID2, allowing ID2 to stabilize.

[0264] ID2≈Vbe / R1

[0265] ID1=I1-ID2

[0266] In this embodiment, Vbe is a constant value, approximately 0.7 V. By adjusting the value of the resistor R1 , the values ​​of the currents ID1 and ID2 can be adjusted to achieve the purpose of adjusting the brightness of the LED components D1 and D2 .

[0267] In some embodiments, the number of LEDs included in LED assembly D1 is less than or equal to the number of LEDs included in LED assembly D2.

[0268] In some embodiments, LED assemblies D1 and D2 are configured to have different colors or color temperatures.

[0269] In some embodiments, the transistor Q1 can be replaced by a field effect transistor, which does not affect the technical effect to be achieved by the present application.

[0270] FIG25B is a schematic diagram of the circuit structure of an LED lamp according to another embodiment of the present application. The circuit structure of this embodiment is similar to that of the embodiment described in FIG25A , except that in this embodiment, the LED module 30a further includes an LED component D3, and the shunt circuit 20a further includes a transistor Q2 and resistors R3 and R4. The anode of LED component D1 is electrically connected to the anodes of LED components D2 and D3, and is also electrically connected to the first output terminal of constant current source A1. The cathode of LED component D1 is electrically connected to the collector of transistor Q1. The emitter of transistor Q1 is electrically connected to the second pin of resistor R1, and its base is electrically connected to the first pin of resistor R2. The second pin of resistor R2 is electrically connected to the cathode of LED component D2 and the first pin of resistor R1. The collector of transistor Q2 is electrically connected to the second pin of resistor R1, its emitter is electrically connected to a common ground, and its base is electrically connected to the first pin of resistor R4. The second pin of the resistor R4 is electrically connected to the cathode of the LED assembly D3 and the first pin of the resistor R3. The second pin of the resistor R3 is electrically connected to the common ground. The second output terminal of the constant current source A1 is electrically connected to the common ground.

[0271] The principle of the shunt circuit regulating the current of three LED components in this embodiment is similar to that of the embodiment described in FIG25A , except that an additional LED component D3 is added in this embodiment. The current relationship in this embodiment satisfies the following equation:

[0272] I1=ID1+ID2+ID3

[0273] ID3≈IR3

[0274] ID2≈IR1

[0275] ID1≈IQ1

[0276] In this embodiment, IR2 and IR4 can be ignored.

[0277] so:

[0278] ID3≈Vbe / R3

[0279] ID2≈Vbe / R1

[0280] ID1=I1–ID2–ID3

[0281] In this embodiment, Vbe is a constant value, approximately 0.7 V. By adjusting the resistance values ​​of resistors R1 and R3, the magnitudes of currents ID2, ID3, and ID1 can be adjusted, thereby adjusting the brightness of LED components D1, D2, and D3.

[0282] In this embodiment, the number of diodes included in the LED assembly D1 is less than or equal to the number of LEDs included in the LED assembly D2; the number of LEDs included in the LED assembly D2 is less than or equal to the number of LEDs included in the LED assembly D3.

[0283] In some embodiments, the LED assemblies D1 , D2 , D3 are configured to have different colors or color temperatures.

[0284] In some embodiments, transistors Q1 and Q2 can be replaced by field-effect transistors without affecting the technical effects to be achieved by the present application.

[0285] Through the configuration of the above embodiment, only one constant current drive circuit is required to control three LED assemblies and achieve the function of adjusting color temperature or color. In particular, when the number of light-emitting diodes included in the LED assemblies varies, current regulation of different LED assemblies can still be achieved.

[0286] FIG25C is a schematic diagram of the circuit structure of an LED lamp according to another embodiment of the present application. The circuit structure of the LED lamp in this embodiment is similar to that of the embodiment described in FIG25A , except that the transistors used in the shunt circuit 20a in this embodiment are PNP transistors, whereas the transistors used in the embodiment described in FIG25A are NPN transistors. In this embodiment, the constant current drive circuit 10a includes a constant current source A1, the LED module 30a includes LED components D1 and D2, and the shunt circuit 20a includes a transistor Q1 and resistors R1 and R2. The emitter of transistor Q1 is electrically connected to the first pin of resistor R1 and the first output terminal of constant current source A1, the collector is electrically connected to the anode of LED component D1, and the base is electrically connected to the first pin of resistor R2. The second pin of resistor R2 is electrically connected to the second pin of resistor R1 and the anode of LED component D2. The cathodes of LED components D1 and D2 are electrically connected and to a common ground. The second output terminal of the constant current source A1 is electrically connected to the common ground terminal.

[0287] The operating principle of the shunt circuit 20a in this embodiment is similar to that of the embodiment described in Figures 25A and 5B and will not be further described here. In this embodiment, since the current of IR2 is small, it can be ignored. Its current satisfies the following relationship:

[0288] ID2≈Vbe / R1

[0289] ID1=I1–ID2

[0290] By adjusting the value of the resistor R1 , the values ​​of the currents ID1 and ID2 can be adjusted, thereby adjusting the brightness of the LED components D1 and D2 .

[0291] In some embodiments, the number of LEDs included in LED assembly D1 is less than or equal to the number of LEDs included in LED assembly D2.

[0292] In some embodiments, the LED assemblies D1 , D2 are configured to have different colors or color temperatures.

[0293] In some embodiments, the transistor Q1 can be replaced by a field effect transistor without affecting the technical effect to be achieved by the present application.

[0294] Through the configuration of the above embodiment, only one constant current drive circuit is required to control two LED assemblies and achieve the function of adjusting color temperature or color. In particular, when the number of light-emitting diodes included in the LED assemblies varies, current regulation of different LED assemblies can still be achieved.

[0295] Through the description of the above embodiments, those skilled in the art can reasonably expand the embodiments and perform current diversion and regulation on multiple LED components, rather than being limited to two or three channels.

[0296] The "single LED filament" or "one LED filament" referred to in this application refers to a structure formed by connecting the aforementioned conductor segments and LED segments together, or consisting solely of LED segments (or LED chip units), having an identical and continuous light conversion layer (including an identical and continuously formed top or bottom layer), and having only two conductive electrodes at both ends electrically connected to the conductive support of the bulb. A structure that meets the above structural description is referred to in this application as a single LED filament structure.

[0297] This application has been disclosed above with reference to preferred embodiments. However, those skilled in the art should understand that these embodiments are merely illustrative of some embodiments of the present application and should not be construed as limiting. It should be noted that any equivalent variations and substitutions to these embodiments, or reasonable combinations between these embodiments (particularly the LED filament embodiment in FIG. 4 combined with the light bulb embodiment in FIG. 4 ), are intended to be encompassed within the scope of this application. Therefore, the scope of protection of this application shall be determined by the scope defined in the appended claims.

Claims

1. An LED filament, the LED filament comprising an LED chip unit, a light conversion layer, and electrodes, characterized in that, The light conversion layer covers the LED chip unit and part of the electrodes, and the color of the light emitted by the LED filament after it is lit is different from the color of the light conversion layer.

2. The LED lamp as described in claim 1, characterized in that, When the LED filament is not lit, the surface of the LED filament is white, gray, black, blue, green, or purple.

3. An LED light, characterized in that, Include: A constant current drive circuit includes a first output terminal and a second output terminal to provide a constant current circuit. An LED module includes at least two LED components coupled to the constant current drive circuit for receiving the constant current and lighting up. as well as, The shunt circuit is electrically connected to the constant current drive circuit and the LED module to distribute the current to different LED components.

4. The LED lamp as described in claim 3, characterized in that, The LED assembly comprises one light-emitting diode or multiple light-emitting diodes connected in series.

5. The LED lamp as described in claim 4, characterized in that, The different LED components contain different numbers of light-emitting diodes.

6. The LED lamp as described in claim 4, characterized in that, The different LED components have different color temperatures or colors.

7. The LED lamp as described in claim 3, characterized in that, The LED module includes a first LED component and a second LED component.

8. The LED lamp as described in claim 7, characterized in that, The shunt current includes a first transistor, a first resistor, and a second resistor. The collector of the first transistor is electrically connected to the cathode of the first LED assembly, the emitter of the first transistor is electrically connected to the first ground terminal, the base of the first transistor is electrically connected to the first pin of the second resistor, the second pin of the first resistor is electrically connected to the cathode of the second LED assembly and the first pin of the first resistor, the second pin of the first resistor is electrically connected to the first ground terminal, the anode of the first LED assembly is electrically connected to the anode of the second LED assembly and is electrically connected to the first output terminal of the constant current drive circuit, and the second output terminal of the constant current drive circuit is electrically connected to the first ground terminal.

9. The LED lamp as described in claim 7, characterized in that, The number of light-emitting diodes included in the first LED component is less than or equal to the number of light-emitting diodes included in the second LED component.

10. The LED lamp as described in claim 8, characterized in that, The first resistor is a variable resistor.

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