A light decay compensation method for LED lamps based on accumulated lighting time length and a lamp

Abstract

A light decay compensation method for LED lamps based on accumulated lighting time length and a lamp, comprising LED lamp beads, a driving circuit, an MCU and a nonvolatile memory. The method comprises: the MCU continuously accumulates the lighting time length of the LED lamp beads and stores them in the nonvolatile memory; the MCU pre-stores light decay compensation parameters corresponding to the LED lamp beads, the parameters comprising a plurality of compensation time nodes and the current compensation amount of each node corresponding to the light decay curve data of the lamp beads, which is determined according to the corresponding light flux attenuation amount; the MCU compares the current accumulated lighting time length with each compensation time node in turn, and when a node is reached, controls the driving circuit to increase the output current by the current compensation amount corresponding to the node, the output current remains constant between adjacent nodes, and the output current remains unchanged after the last node is reached. The compensation amount is matched with the actual light decay characteristics of the specific lamp beads, and the compensation precision is high and the cost is low.

Description

Technical Field

[0001] This invention relates to the field of intelligent lighting technology, and in particular to a method and fixture for compensating for light decay in LED lamps based on cumulative lighting time. Background Technology

[0002] During prolonged use, LED chips experience a gradual decrease in luminous flux due to factors such as material aging, phosphor degradation, and accumulated junction temperature, a phenomenon known as "light decay." The degree of light decay in LED chips is closely related to the cumulative usage time and operating temperature, and chips of different brands, models, and packaging types exhibit significantly different light decay curves at different operating temperatures and color temperatures.

[0003] In the field of architectural lighting, there are rigid regulations on illuminance, such as national standards (e.g., GB 50034 "Standard for Lighting Design of Buildings") and AA-level illuminance requirements. Although luminaires may meet these standards when they leave the factory, light decay will cause a continuous decrease in illuminance as they are used over time, and eventually they may no longer meet the standard requirements. This results in the problem that the nominal lifespan of the luminaire (when the LEDs are not in failure) is much longer than its effective illuminance lifespan (the time when the illuminance still meets the standard).

[0004] The first type is a constant current drive scheme without any compensation. The luminaire driver circuit outputs a constant current from the factory until the end of its lifespan without any adjustment, and the luminous flux of the lamp beads continuously decreases with the duration of use. Its inherent defects are: the illuminance decreases monotonically over time, and may fall below the national standard requirements in the later stages of its lifespan; the nominal lifespan of the luminaire is much greater than its effective illuminance lifespan, resulting in resource waste; in mandatory illuminance scenarios such as educational lighting and medical lighting, the luminaire may be judged as unqualified in advance due to insufficient illuminance.

[0005] The second approach is to leave an overdrive margin at the factory. The drive current is set 10%–15% higher than the nominal value at the factory to ensure sufficient illuminance margin even after the lamp's light decays. Its inherent drawbacks are: the initial illuminance is too high, resulting in initial energy consumption exceeding actual needs; overdrive causes the lamp's junction temperature to rise, accelerating light decay and creating a vicious cycle of "compensation-accelerated decay"; the compensation amount is a one-time fixed value, unable to match the non-linear changes in the light decay curve, and unable to accurately control the illuminance level at the end of its lifespan.

[0006] The third type is a closed-loop feedback compensation scheme based on light sensors. A light sensor is installed in the luminaire to detect luminous flux or illuminance in real time, and the drive current is adjusted based on the comparison with the target value. Its inherent drawbacks include: increased costs due to the need for additional hardware such as light sensors and signal conditioning circuits; sensor aging, sensitivity drift, and temperature-related changes; low detection values ​​due to dust or contamination on the sensor surface, leading to overcompensation; significant impact of sensor installation location on detection results, resulting in numerous design constraints; stability issues in the feedback loop requiring careful tuning of control parameters; and the sensor's lifespan may be shorter than the luminaire's design lifespan.

[0007] The fourth method is a simple timed, uniformly increasing current scheme. A timer is set in the drive circuit to uniformly increase the drive current by a fixed amount at fixed intervals. Its inherent drawbacks are: the compensation amount and interval do not match the actual light decay curve; it does not differentiate between the brand, model, package, color temperature, and operating temperature of the LED chips, resulting in low compensation accuracy, potentially leading to undercompensation or overcompensation in some stages; it typically lacks a reliable mechanism for storing accumulated data after power failure; and it does not consider safety constraints after compensation. Summary of the Invention

[0008] To address the problems existing in the prior art, the technical problems to be solved by the present invention include: how to match the compensation amount with the actual light decay law of a specific LED chip without adding any optical detection elements; how to ensure that the cumulative lighting duration used as the compensation trigger reference is effective and not reset when the lamp is frequently switched on and off and powered off; how to increase the driving current for compensation without exceeding the safety boundaries of the lamp's certified power and components and junction temperature; and how to reduce the burden of controller operation and memory writing while maintaining stable light quality at each stage.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for compensating for light decay in an LED lamp, the lamp comprising LED chips, a driving circuit, an MCU, and a non-volatile memory, the method comprising the following steps: S1: The MCU continuously calculates the lighting time of the LED beads to obtain the cumulative lighting time, and stores the cumulative lighting time in the non-volatile memory so that the cumulative lighting time is not lost after power failure, and continues to accumulate on the basis of the stored cumulative lighting time after power is restored; S2: The MCU pre-stores the light decay compensation parameters corresponding to the LED beads. The light decay compensation parameters include multiple compensation time nodes and the current compensation amount corresponding to each compensation time node. The current compensation amount corresponding to each compensation time node is determined according to the light flux attenuation amount corresponding to the compensation time node in the light decay curve data of the LED beads. S3: The MCU compares the current cumulative lighting duration with the plurality of compensation time nodes in sequence; S4: When the cumulative lighting duration reaches one of the multiple compensation time nodes, the MCU controls the drive circuit to increase the output current of the compensation time node corresponding to the current compensation amount, and the output current of the drive circuit remains constant between two adjacent compensation time nodes. S5: When the cumulative lighting duration reaches the last compensation time node and the corresponding current compensation is completed, the output current of the drive circuit remains unchanged.

[0010] Furthermore, the multiple compensation time points include a cumulative lighting duration of 20,000 hours, 30,000 hours, 40,000 hours, and 50,000 hours; and no light decay compensation is performed before the cumulative lighting duration reaches 20,000 hours.

[0011] Furthermore, the current compensation amount corresponding to each compensation time node is determined in the following way: Based on the light decay curve of the LED bead, the cumulative lumen attenuation ratio corresponding to the compensation time node is obtained; the initial lumen value of the lamp is multiplied by the cumulative lumen attenuation ratio to obtain the lumen attenuation value corresponding to the compensation time node; the lumen attenuation value is divided by the lumen value per watt of power of the LED bead to obtain the power value to be compensated corresponding to the compensation time node; the power value to be compensated is divided by the actual operating voltage of the lamp to obtain the cumulative compensation current value corresponding to the compensation time node; the cumulative compensation current value corresponding to the compensation time node is subtracted from the cumulative compensation current value corresponding to the previous compensation time node to obtain the current compensation amount corresponding to the compensation time node.

[0012] Furthermore, the light decay curve data of the LED lamp bead includes light decay data under multiple operating temperature conditions; before the LED lamp leaves the factory, an operating temperature is selected from the multiple operating temperature conditions according to the design operating conditions of the LED lamp, and the current compensation amount corresponding to each compensation time node is predetermined based on the light decay data under the selected operating temperature and stored in the MCU; the MCU does not detect the actual operating temperature of the LED lamp bead during the compensation process.

[0013] Furthermore, after determining the current compensation amount corresponding to each compensation time node, a verification step is also included: verifying that the total output power of the lamp after compensation does not exceed the certified nominal power range of the lamp; and verifying that the component temperature, expected lifespan of the components, and junction temperature of the LED beads are all within the preset safety threshold range under the maximum compensation current condition; if any of the above conditions are not met, the current compensation amount of the corresponding compensation time node is reduced until it is met.

[0014] Furthermore, the light decay compensation parameter is related to the color temperature of the LED chip, and different color temperatures of LED chips correspond to different light decay compensation parameters.

[0015] Furthermore, the non-volatile memory is a NOR Flash memory; the LED lamp also includes a power failure detection circuit; the MCU updates the cumulative lighting duration at a preset period during the LED lamp bead lighting period, and writes the current cumulative lighting duration into the NOR Flash memory when the power failure detection circuit detects that the LED lamp has lost power.

[0016] Furthermore, the current compensation amount corresponding to each compensation time node does not exceed 2% of the output current of the driving circuit before compensation at that compensation time node, so that the change in color temperature and color rendering index of the LED bead between two adjacent compensation time nodes is within a preset range.

[0017] Secondly, the present invention provides an LED lamp with light decay compensation function, comprising: an LED chip; a driving circuit for providing driving current to the LED chip; an MCU connected to the driving circuit for controlling the output current of the driving circuit; and a non-volatile memory connected to the MCU for storing cumulative lighting duration and light decay compensation parameters, wherein the light decay compensation parameters include multiple compensation time nodes and current compensation amounts corresponding to each compensation time node, and the current compensation amounts corresponding to each compensation time node are determined based on the light decay curve data of the LED chip; the MCU is configured to: hold The cumulative lighting duration of the LED beads is continuously calculated and stored in the non-volatile memory, so that the cumulative lighting duration is not lost after power failure and continues to accumulate after power is restored; the current cumulative lighting duration is compared with the multiple compensation time nodes in sequence; when the cumulative lighting duration reaches a compensation time node, the drive circuit is controlled to increase the output current of the compensation time node by the current compensation amount corresponding to the compensation time node, and the output current of the drive circuit is kept constant between two adjacent compensation time nodes; when the cumulative lighting duration reaches the last compensation time node and the corresponding current compensation is completed, the output current of the drive circuit remains unchanged.

[0018] Furthermore, the LED lamp also includes a dimming circuit connected to the MCU, and the MCU achieves light decay compensation by superimposing a compensation current corresponding to the current compensation amount in the dimming circuit.

[0019] By adopting the above technical solution, the present invention has the following beneficial effects.

[0020] Firstly, this invention pre-stores the light decay curve data corresponding to the LED chips in the MCU. The MCU can determine the compensation current by simply querying the pre-stored data based on the cumulative lighting time, eliminating the need for any optical detection elements in the lamp or the need to detect the actual operating temperature of the LED chips. This solution transforms the compensation control from "closed-loop real-time feedback" to "open-loop predictive feedforward." Based on the light decay curve data provided by the LED chip manufacturer, it converts the physical quantity (luminous flux) that originally needed to be detected in real time into a time function that can be calculated in advance. This architecture choice is not simply about omitting sensors, but rather based on the predictability of LED light decay patterns: throughout the entire lifespan of up to 50,000 hours, the compensation accuracy is always determined by the pre-stored data, unaffected by physical processes such as sensor aging, drift, dust accumulation, and contamination, thus achieving high long-term reliability while eliminating optical detection hardware.

[0021] Secondly, the compensation accuracy is high, capable of matching the actual light decay characteristics of specific LED chips. Existing simple compensation schemes treat LED chips as general-purpose components, using uniform compensation parameters. However, in reality, the light decay patterns of LED chips vary significantly under different packaging forms (e.g., 2835, 3030, COB), different color temperatures (e.g., 1800K, 2700K, 5700K), and different operating temperatures. This invention pre-stores the light decay curve data of each LED chip and calculates the compensation amount accordingly, ensuring that the compensation matches the actual attenuation. The same lighting platform can accurately adapt to LED chips of different brands, models, packages, and color temperatures simply by replacing the light decay parameter table in the MCU. This characteristic of unchanged hardware and adapted parameters has outstanding engineering value in mass production.

[0022] Thirdly, the use of stepped discrete compensation brings the dual benefits of stable light quality and memory lifespan protection. This invention performs stepped compensation at specific time points instead of continuous fine-tuning, ensuring a constant driving current between adjacent compensation nodes. Light quality parameters such as color temperature and color rendering index of the LED chips remain stable during this stage, avoiding light quality fluctuations caused by continuous fine-tuning current. Simultaneously, it significantly reduces the computational burden on the MCU and the number of writes to non-volatile memory, which is beneficial for low-power, long-life operation.

[0023] Fourth, the power-off memory function ensures that the compensation strategy is effectively executed throughout the entire life cycle of the lamp. LED lamps inevitably experience frequent switching on and off during actual use. Without a reliable time retention mechanism, the accumulated time resets to zero after each power-on, severely delaying the compensation timing or even preventing it from triggering altogether, rendering the entire compensation strategy ineffective. This invention stores the accumulated lighting time in a non-volatile memory and continues accumulating it after power-on, fundamentally ensuring that the time-indexed compensation strategy can be correctly triggered.

[0024] Fifth, the compensation process has safety constraints. An increase in compensation current is inevitably accompanied by an increase in power consumption and temperature rise. This invention incorporates power constraints, temperature, lifespan, and junction temperature constraints as components of the compensation parameter determination process, ensuring that the compensated luminaire always operates within a safe operating range throughout its entire lifespan, preventing safety hazards caused by over-compensation or exceeding the product certification scope.

[0025] Sixth, existing lighting products can obtain the light decay compensation function of this invention through firmware upgrades without modifying hardware design and molds, resulting in low marginal costs for product upgrades. This solution does not add new component types, does not change assembly processes, and does not add testing procedures, thus having no negative impact on supply chain management and production efficiency. Attached Figure Description

[0026] Figure 1 This is a system structure block diagram of an LED lamp with light decay compensation function in an embodiment of the present invention; Figure 2 This is a flowchart of the LED lamp light decay compensation method in an embodiment of the present invention.

[0027] Explanation of reference numerals in the attached figures: 1—LED lamp bead; 2—Driver circuit; 3—MCU; 4—Non-volatile memory; 5—Power-down detection circuit; 6—Dimming circuit. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0029] It should be noted that the descriptions involving "first," "second," etc., in this invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0030] See Figure 1 and Figure 2This embodiment provides a method for compensating for light decay in an LED lamp. The lamp includes an LED chip 1, a driving circuit 2, an MCU 3, and a non-volatile memory 4. The driving circuit 2 provides driving current to the LED chip 1; the MCU 3 is connected to the driving circuit 2 and is used to control the output current of the driving circuit 2; the non-volatile memory 4 is connected to the MCU 3 and is used to store the cumulative lighting duration and light decay compensation parameters. The method includes the following steps.

[0031] S1: MCU3 continuously calculates the lighting time of LED bead 1 to obtain the cumulative lighting time, and stores the cumulative lighting time in non-volatile memory 4 so that the cumulative lighting time is not lost after power failure, and continues to accumulate on the basis of the stored cumulative lighting time after power is restored.

[0032] S2: The MCU3 pre-stores the light decay compensation parameters corresponding to LED bead 1. These light decay compensation parameters include multiple compensation time nodes and the current compensation amount corresponding to each compensation time node. The current compensation amount corresponding to each compensation time node is determined according to the luminous flux attenuation amount corresponding to the compensation time node in the light decay curve data of LED bead 1.

[0033] S3: MCU3 compares the current cumulative lighting duration with the multiple compensation time nodes in sequence.

[0034] S4: When the cumulative lighting time reaches one of the multiple compensation time nodes, the MCU3 controls the drive circuit 2 to increase the output current of the compensation time node corresponding to that compensation time node, and the output current of the drive circuit 2 remains constant between two adjacent compensation time nodes.

[0035] S5: When the cumulative lighting time reaches the last compensation time node and the corresponding current compensation is completed, the output current of the drive circuit 2 remains unchanged.

[0036] This embodiment proposes a new LED light decay compensation technology path, which transforms the physical detection problem into a data prediction problem. The key information required for light decay compensation is transformed from real-time optical signals into a combination of time information and pre-stored data tables, which simplifies the system hardware architecture while improving long-term reliability.

[0037] Example 2: Setting the Compensation Time Node In this embodiment, the multiple compensation time nodes include a cumulative lighting time of 20,000 hours, 30,000 hours, 40,000 hours and 50,000 hours, and no light decay compensation is performed before the cumulative lighting time reaches 20,000 hours.

[0038] This node setting reflects the principle of sufficiency and necessity in engineering. LED light decay typically exhibits rapid initial decay in the early stages (e.g., the first 10,000 hours), gradually leveling off thereafter. Furthermore, the initial decay rate has limited impact on achieving the required light intensity. Therefore, adopting a strategy of no compensation in the initial stage and phased compensation in the later stages is reasonable. The compensation current increases in a stepwise manner at each compensation time node, remaining constant between adjacent nodes.

[0039] The stepped compensation provides two additional benefits. First, it ensures constant light quality across all stages. The color temperature and color rendering index (CRI) of LED chips are closely related to the drive current. Stepped compensation ensures that the color temperature and CRI of the luminaire remain stable within each compensation stage (approximately 10,000 hours), so users will not perceive color temperature drift. This is particularly important for scenarios with high requirements for consistent light quality, such as educational lighting, exhibition lighting, and medical lighting. Second, it protects the lifespan of non-volatile memory. Stepped compensation, combined with the power-down write mechanism described later, significantly reduces the number of write cycles to the memory, ensuring that it will not fail due to exhaustion of write cycles throughout the entire lifespan of the luminaire.

[0040] Example 3: Method for Determining Current Compensation Amount In this embodiment, the current compensation amount corresponding to each compensation time node is precisely determined in incremental form as follows.

[0041] First, based on the light decay curve of LED chip 1, obtain the cumulative lumen attenuation ratio corresponding to the compensation time node. Second, multiply the initial lumen value of the luminaire by the cumulative lumen attenuation ratio to obtain the lumen attenuation value corresponding to the compensation time node. Then, divide this lumen attenuation value by the lumen value per watt of LED chip 1 to obtain the power compensation value corresponding to the compensation time node. Next, divide this power compensation value by the actual operating voltage of the luminaire to obtain the cumulative compensation current value corresponding to the compensation time node. Finally, subtract the cumulative compensation current value corresponding to the previous compensation time node from the cumulative compensation current value corresponding to the compensation time node to obtain the current compensation amount that should be increased at this compensation time node.

[0042] Taking the Seoul 3030 packaged LED chip STWSC2PB-E0 (2700K) at 70℃ as an example, the light decay data at each compensation time point and the compensation amount determined by the above method are shown in the table below:

[0043] .

[0044] As shown in the table above, without compensation, the luminous flux maintenance rate is approximately 93.78% after 50,000 hours. However, after staged compensation according to this embodiment, the luminous flux maintenance rate recovers to approximately 100% at each stage, and the illuminance of the luminaire remains essentially constant throughout its entire lifespan. Since the current compensation amount at each compensation time point is directly calculated from the luminous flux attenuation amount corresponding to that point on an incremental basis, the equivalent maintenance rate after compensation converges precisely to the initial level, and there is no cumulative overcompensation.

[0045] It should be noted that this embodiment calculates the increment of each node precisely according to the optical decay curve (where the increment of the first node is 2.91%), which is an independent implementation method. When there is a stricter limit on the optical quality fluctuation caused by single-step current change, the implementation method described in Embodiment Six below can be adopted to limit the single-step compensation amount to within 2%. If it is desired to simultaneously meet the requirements of accurate compensation and single-step compensation not exceeding 2%, the number of compensation time nodes can be appropriately increased and the node interval shortened (for example, one node is set every 5000 hours) so that the current compensation increment of each node falls within 2%.

[0046] This method for determining the compensation amount ensures that the increased current in each compensation stage can be traced back to the light decay data of the LED chip manufacturer, the photoelectric parameters of the luminaire, and the safety constraints. The compensation amount is based on evidence, can be calculated, verified, and traceable, providing clear technical support for the design verification, quality control, and product certification of luminaires.

[0047] Example 4: Parameter Determination Based on Preset Operating Temperature LED chips exhibit different light decay curves at different operating temperatures. In this embodiment, the light decay curve data of LED chip 1 includes light decay data under multiple operating temperature conditions. Before the LED lamp leaves the factory, based on the design operating conditions of the LED lamp, an operating temperature is selected from the multiple operating temperature conditions (for example, 70°C is selected based on the typical heat dissipation design and environmental conditions of the lamp). Based on the light decay data at the selected operating temperature, the current compensation amount corresponding to each compensation time node is predetermined according to the method in Embodiment 3, and then stored in the MCU3.

[0048] During the operation of the lamp, MCU3 does not detect the actual operating temperature of LED bead 1, but directly performs compensation according to the pre-set compensation parameters. Thus, this embodiment achieves compensation that matches the specific operating temperature conditions of the LED bead without adding a temperature sensor or introducing any temperature detection link during operation, further ensuring the characteristics of a pure open-loop feedforward architecture and no detection element.

[0049] Example 5: Safety Verification of Compensation Parameters and Correlation with Color Temperature In this embodiment, after determining the current compensation amount corresponding to each compensation time node, a safety verification step is also included. On the one hand, it is verified that the total output power of the lamp after compensation does not exceed the certified nominal power range of the lamp (e.g., not exceeding the CCC certified nominal power); on the other hand, under the maximum compensation current condition, it is verified that the component temperature of the drive circuit 2, the expected lifespan of the components, and the junction temperature of the LED beads 1 are all within the preset safety threshold range. If any of the above conditions are not met, the current compensation amount at the corresponding compensation time node is reduced until all conditions are met.

[0050] An increase in compensation current inevitably leads to increased power consumption and temperature rise, potentially causing safety risks or exceeding product certification limits. Existing technologies rarely incorporate safety verification into optical attenuation compensation schemes. This embodiment integrates safety constraints as part of the compensation parameter determination process, ensuring the compensation scheme operates within a safe range throughout its entire lifespan.

[0051] Furthermore, in this embodiment, the light decay compensation parameters are related to the color temperature of the LED bead 1, with different color temperatures corresponding to different light decay compensation parameters. This is because LED beads of different color temperatures typically use phosphors with different ratios, resulting in different light decay patterns. Pre-storing corresponding parameters for different color temperatures can further improve the compensation accuracy.

[0052] To illustrate the necessity of pre-storing parameters for specific LED chips, using Seoul 3030 packaged LED chips at 70°C: STWSC2PB-E0 (2700K) maintained a luminous flux of 93.78% after 50,000 hours, requiring approximately 6.22% compensation; while STWSC12S-E1H10000 (2700K) maintained a luminous flux of 70.01% after 50,000 hours, requiring approximately 29.99% compensation. The required compensation differs by nearly five times. Using uniform compensation parameters would inevitably lead to undercompensation for one type of LED chip and overcompensation for another. This invention fundamentally avoids these problems by pre-storing the individual luminous decay data for each LED chip and calculating the compensation amount separately.

[0053] Example 6: Single-step compensation amount limitation In this embodiment, the current compensation amount corresponding to each compensation time node does not exceed 2% of the output current of the driving circuit 2 before compensation at that compensation time node, so that the change in color temperature and color rendering index of LED bead 1 between two adjacent compensation time nodes is within a preset range. Limiting the single-step compensation amount to a small range ensures that the changes in color temperature and color rendering index caused by each current adjustment are within a range imperceptible to the human eye, further improving the consistency of light quality. As mentioned above, when the single-step increment calculated according to the light decay curve exceeds 2%, the increment of each step can be kept within 2% by increasing the number of compensation time nodes and shortening the node interval, thereby balancing compensation accuracy and single-step limitation.

[0054] Example 7: Memory Type and Power-Down Write Mechanism In this embodiment, the non-volatile memory 4 is a NOR Flash memory with an erase / write lifespan of approximately 1,000,000 cycles. The LED lamp also includes a power-down detection circuit 5 connected to the MCU3. During the illumination of the LED beads 1, the MCU3 internally updates the cumulative illumination duration at a preset period (e.g., every 1 second); when the power-down detection circuit 5 detects a power failure in the LED lamp, the MCU3 writes the current cumulative illumination duration into the NOR Flash memory 4.

[0055] The power-down triggered write mechanism described above has two advantages. First, because the NOR Flash is written only once during each power outage, rather than frequently at fixed time intervals, the number of writes over the entire lifespan can be reduced to the same order of magnitude as the number of times the lamp is turned on and off, far below the NOR Flash's erase / write lifespan limit of approximately 1,000,000 cycles. This ensures that the memory will not fail due to exhaustion of write cycles during the lamp's entire lifespan. Second, the power-down triggered write mechanism, combined with the high-frequency internal updates during lighting, avoids the problem of lost lighting time due to sudden power outages between writes in fixed-time interval write schemes, making the recording of accumulated lighting time more accurate and reliable.

[0056] Example 8: LED lamps with light decay compensation function See Figure 1 This embodiment provides an LED lamp with light decay compensation function, including an LED chip 1, a driving circuit 2, an MCU 3, and a non-volatile memory 4. The driving circuit 2 provides driving current to the LED chip 1; the MCU 3 is connected to the driving circuit 2 and controls the output current of the driving circuit 2; the non-volatile memory 4 is connected to the MCU 3 and stores the cumulative lighting time and light decay compensation parameters. These light decay compensation parameters include multiple compensation time nodes and the current compensation amount corresponding to each compensation time node. The current compensation amount corresponding to each compensation time node is determined according to the light decay curve data of the LED chip 1.

[0057] MCU3 is configured to: continuously accumulate and calculate the lighting duration of LED beads 1 and store it in non-volatile memory 4, so that the accumulated lighting duration is not lost after power failure and continues to accumulate after power-on; compare the current accumulated lighting duration with the multiple compensation time nodes in sequence; when the accumulated lighting duration reaches a compensation time node, control the drive circuit 2 to increase the output current of the drive circuit 2 by the current compensation amount corresponding to the compensation time node, and keep the output current of the drive circuit 2 constant between two adjacent compensation time nodes; when the accumulated lighting duration reaches the last compensation time node and the corresponding current compensation is completed, keep the output current of the drive circuit 2 unchanged.

[0058] Further, see Figure 1 The LED lamp also includes a dimming circuit 6 connected to the MCU3. The MCU3 achieves light decay compensation by superimposing a compensation current corresponding to the current compensation amount in the dimming circuit 6. By superimposing the compensation current in the dimming circuit 6, current compensation can be achieved without changing the main structure of the drive circuit 2, making it easy to integrate on existing lamp platforms.

[0059] For existing lighting products, since the light decay compensation function of this invention is mainly implemented through the control logic and pre-stored parameters of MCU3, existing lighting products can obtain this function through firmware upgrades without modifying hardware design and molds, resulting in low marginal cost of product upgrades. At the same time, this solution does not add new component types, does not change the assembly process, and does not add testing procedures, making it fully compatible with the existing supply chain and production process.

[0060] A comparison curve showing the change in luminous flux maintenance rate of the luminaire with the cumulative lighting time. It can be seen that without compensation, the luminous flux maintenance rate decreases monotonically with time, while with the compensation scheme of the present invention, the luminous flux maintenance rate is progressively increased in each compensation stage and maintained at a level close to the initial value, so that the illuminance of the luminaire remains basically constant throughout its entire life cycle.

[0061] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for compensating light decay in an LED lamp, the lamp comprising LED chips, a driving circuit, an MCU, and a non-volatile memory, characterized in that, The method includes the following steps: S1: The MCU continuously calculates the lighting time of the LED beads to obtain the cumulative lighting time, and stores the cumulative lighting time in the non-volatile memory so that the cumulative lighting time is not lost after power failure, and continues to accumulate on the basis of the stored cumulative lighting time after power is restored; S2: The MCU pre-stores the light decay compensation parameters corresponding to the LED beads. The light decay compensation parameters include multiple compensation time nodes and the current compensation amount corresponding to each compensation time node. The current compensation amount corresponding to each compensation time node is determined according to the light flux attenuation amount corresponding to the compensation time node in the light decay curve data of the LED beads. S3: The MCU compares the current cumulative lighting duration with the plurality of compensation time nodes in sequence; S4: When the cumulative lighting duration reaches one of the multiple compensation time nodes, the MCU controls the drive circuit to increase the output current of the compensation time node corresponding to the current compensation amount, and the output current of the drive circuit remains constant between two adjacent compensation time nodes. S5: When the cumulative lighting duration reaches the last compensation time node and the corresponding current compensation is completed, the output current of the drive circuit remains unchanged.

2. The method for compensating for light decay in LED lamps according to claim 1, characterized in that: The multiple compensation time points include a cumulative lighting time of 20,000 hours, 30,000 hours, 40,000 hours, and 50,000 hours; and no light decay compensation is performed before the cumulative lighting time reaches 20,000 hours.

3. The light decay compensation method for LED lamps according to claim 1, characterized in that: The current compensation amount corresponding to each compensation time node is determined in the following way: Based on the light decay curve of the LED beads, obtain the cumulative lumen attenuation ratio corresponding to the compensation time node; Multiply the initial lumen value of the luminaire by the cumulative lumen attenuation ratio to obtain the lumen attenuation value corresponding to the compensation time node; Divide the lumen attenuation value by the lumen value corresponding to the power per watt of the LED lamp bead to obtain the power value to be compensated at the compensation time node. Divide the power value to be compensated by the actual operating voltage of the lamp to obtain the cumulative compensation current value corresponding to the compensation time node; Subtract the cumulative compensation current value corresponding to the previous compensation time node from the cumulative compensation current value corresponding to the current compensation time node to obtain the current compensation amount corresponding to the current compensation time node.

4. The light decay compensation method for LED lamps according to claim 1, characterized in that: The light decay curve data of the LED lamp bead includes light decay data under multiple operating temperature conditions; before the LED lamp leaves the factory, an operating temperature is selected from the multiple operating temperature conditions according to the design operating conditions of the LED lamp, and the current compensation amount corresponding to each compensation time node is predetermined based on the light decay data under the selected operating temperature and stored in the MCU. The MCU does not detect the actual operating temperature of the LED beads during the compensation process.

5. The method for compensating for light decay in LED lamps according to claim 1 or 3, characterized in that: After determining the current compensation amount corresponding to each compensation time node, a verification step is also included: verifying that the total output power of the lamp after compensation does not exceed the certified nominal power range of the lamp; Under the condition of maximum compensation current, verify that the component temperature, expected lifespan of the components, and junction temperature of the LED beads of the driving circuit are all within the preset safety threshold range; if any of the above conditions are not met, reduce the current compensation amount at the corresponding compensation time node until the conditions are met.

6. The method for compensating light decay in LED lamps according to claim 1, characterized in that: The light decay compensation parameter is related to the color temperature of the LED chip, and different color temperatures of LED chips correspond to different light decay compensation parameters.

7. The method for compensating for light decay in LED lamps according to claim 1, characterized in that: The non-volatile memory is a NOR Flash memory; The LED lamp also includes a power failure detection circuit; the MCU updates the cumulative lighting duration at a preset cycle during the LED lamp bead lighting period, and writes the current cumulative lighting duration into the NOR Flash memory when the power failure detection circuit detects that the LED lamp has lost power.

8. The method for compensating for light decay in LED lamps according to claim 1, characterized in that: The current compensation amount corresponding to each compensation time node does not exceed 2% of the output current of the driving circuit before compensation at that compensation time node, so that the color temperature and color rendering index of the LED beads are within a preset range between two adjacent compensation time nodes.

9. An LED lamp with light decay compensation function, characterized in that, include: LED beads; The driving circuit is used to provide driving current to the LED beads; The MCU is connected to the drive circuit and is used to control the output current of the drive circuit. A non-volatile memory, connected to the MCU, is used to store the cumulative lighting time and light decay compensation parameters. The light decay compensation parameters include multiple compensation time nodes and the current compensation amount corresponding to each compensation time node. The current compensation amount corresponding to each compensation time node is determined according to the light decay curve data of the LED beads. The MCU is configured to: continuously accumulate and calculate the lighting duration of the LED beads and store it in the non-volatile memory, so that the accumulated lighting duration is not lost after power failure and continues to accumulate after power is restored; and compare the current accumulated lighting duration with the plurality of compensation time nodes in sequence. When the cumulative lighting time reaches a compensation time node, the control of the drive circuit will increase the output current of the drive circuit by the current compensation amount corresponding to the compensation time node, and keep the output current of the drive circuit constant between two adjacent compensation time nodes. Once the cumulative lighting duration reaches the last compensation time node and the corresponding current compensation is completed, the output current of the drive circuit remains unchanged.

10. The LED lamp with light decay compensation function according to claim 9, characterized in that: The LED lamp also includes a dimming circuit connected to the MCU, and the MCU achieves light decay compensation by superimposing a compensation current corresponding to the current compensation amount in the dimming circuit.

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