Intelligent lighting lamp based on constant current driving

Abstract

The utility model provides a kind of intelligent lighting fixture based on constant current drive, it is related to intelligent lighting technical field, comprising: MCU main control board and LED power board;MCU main control board is equipped with main control MCU, negative feedback operational amplifier and temperature compensation circuit;LED power board is equipped with NPN triode, sampling resistance and power conversion circuit;LED power board drives LED lamp pearl by power conversion circuit;The DAC output pin of main control MCU is connected with the positive input of negative feedback operational amplifier by temperature compensation circuit, the output of negative feedback operational amplifier is connected to the base of NPN triode, sampling resistance and the negative input of negative feedback operational amplifier are all connected with the emitter of NPN triode, LED lamp pearl is connected with the collector of NPN triode;Wherein, negative feedback operational amplifier, NPN triode and sampling resistance constitute closed loop control loop, so that NPN triode is in constant current state, to carry out constant current drive to LED lamp pearl.

Description

Technical Field

[0001] This utility model relates to the field of intelligent lighting technology, and in particular to an intelligent lighting fixture based on constant current drive. Background Technology

[0002] With the continuous development of smart lighting technology, users have placed higher demands on the stability, dimming effect, and intelligence of lighting fixtures. Currently, traditional smart lighting fixtures mostly use PWM control to adjust LED brightness; however, this control method easily leads to flickering, affecting lighting quality and user experience. When taking photos with mobile phones or other devices, stripes may sometimes appear. Flickering may also occur when the dimming is low.

[0003] Furthermore, as the operating temperature of the lamp and the ambient temperature increase, the luminous efficiency of the lamp will decrease. This means the actual brightness of the lamp will be lower than its nominal brightness. Some solutions use temperature sensors to compensate for this. However, this increases costs because the NTC (light temperature sensor) can fluctuate significantly, potentially leading to overcompensation and accelerating the aging of the LED chips. Utility Model Content

[0004] In view of the shortcomings of the prior art, the purpose of this utility model embodiment is to provide an intelligent lighting fixture based on constant current drive, which can solve the technical problems of existing PWM control methods that easily cause the lamp to flicker and the lamp's luminous efficiency to decrease as the lamp's operating temperature and ambient temperature increase.

[0005] This utility model embodiment proposes an intelligent lighting fixture based on constant current drive, including: an MCU main control board and an LED power supply board; the MCU main control board is equipped with a main control MCU with DAC output function, a negative feedback operational amplifier, and a temperature compensation circuit; the LED power supply board is equipped with an external high-power NPN transistor, a sampling resistor, and a power conversion circuit for converting AC input power into LED driving voltage; the LED power supply board drives LED beads through the power conversion circuit; the DAC output pin of the main control MCU is connected to the positive input of the negative feedback operational amplifier through the temperature compensation circuit, the output of the negative feedback operational amplifier is connected to the base of the NPN transistor, the sampling resistor and the negative input of the negative feedback operational amplifier are both connected to the emitter of the NPN transistor, and the LED beads are connected to the collector of the NPN transistor; The negative feedback operational amplifier, the NPN transistor, and the sampling resistor form a closed-loop control circuit, which keeps the NPN transistor in a constant current state to drive the LED bead with a constant current.

[0006] The beneficial effects of the technical solution provided by this utility model embodiment include at least the following: (1) In this embodiment of the present invention, the negative feedback operational amplifier, the NPN transistor and the sampling resistor form a closed-loop control circuit, so that the NPN transistor is in a constant current state to drive the LED beads with constant current, thereby eliminating the flickering of the lamp under traditional PWM control and realizing stable lighting of the lamp.

[0007] (2) In this embodiment of the utility model, the temperature compensation circuit can adjust the current according to the temperature change, thereby ensuring the brightness of the LED beads is stable. This compensation can avoid the brightness reduction caused by the temperature rise, thereby maintaining the expected lighting effect of the lamp and realizing the stable lighting of the lamp. Attached Figure Description

[0008] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this invention. Throughout the drawings, the same reference numerals denote the same components. Obviously, the drawings described below are merely some embodiments of this invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0009] Figure 1 This is a schematic diagram of the overall structure of an intelligent lighting fixture based on constant current drive, provided by an embodiment of this utility model.

[0010] Figure 2 This is a detailed structural diagram of an intelligent lighting fixture based on constant current drive provided by an embodiment of this utility model.

[0011] Figure 3 This is a schematic diagram of a temperature compensation circuit provided in an embodiment of the present invention.

[0012] Figure 4 This is a schematic diagram of another temperature compensation circuit provided in an embodiment of the present invention.

[0013] Figure labeling: 1-MCU main control board; 11-Main control MCU; 12-Negative feedback operational amplifier; 13-Temperature compensation circuit; 131-Diode array; 132-Grounding resistor; 133-First resistor; 134-Second resistor; 135-Third resistor; 136-Fourth resistor; 137-Positive temperature coefficient thermistor; 2-LED power supply board; 21-NPN transistor; 22-Sampling resistor; 23-Power conversion circuit; 3-LED bead. Detailed Implementation

[0014] To enable those skilled in the art to better understand the technical solutions in the embodiments of this utility model, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. It should be understood that these descriptions are exemplary only and are not intended to limit the scope of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this utility model.

[0015] Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts disclosed in this utility model.

[0016] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this invention.

[0017] Reference manual attached Figures 1 to 4 The present invention provides a structure for an intelligent lighting fixture based on constant current drive, comprising: an MCU main control board 1 and an LED power supply board 2.

[0018] The MCU main control board 1 is equipped with a main control MCU 11 with DAC output function, a negative feedback operational amplifier 12, and a temperature compensation circuit 13. The output voltage range of the DAC output pin is 0-5V.

[0019] The LED power board 2 is equipped with an external high-power NPN transistor 21, a sampling resistor 22, and a power conversion circuit 23 for converting AC input power into LED driving voltage.

[0020] LED power board 2 drives LED beads 3 through power conversion circuit 23. The DAC output pin of the main control MCU 11 is connected to the positive input of negative feedback operational amplifier 12 through temperature compensation circuit 13. The output of negative feedback operational amplifier 12 is connected to the base of NPN transistor 21. Sampling resistor 22 and negative input of negative feedback operational amplifier 12 are both connected to the emitter of NPN transistor 21. LED beads 3 are connected to the collector of NPN transistor 21. When the brightness of LED beads 3 needs to be adjusted, the main control MCU 11 lowers or raises the DAC output voltage according to user instructions or sensing signals. The negative feedback operational amplifier adjusts the output voltage according to the change in positive input voltage, thereby changing the base current of external high-power NPN transistor 21, so that the current through LED beads 3 changes accordingly, realizing synchronous adjustment of LED brightness.

[0021] In this embodiment of the invention, a closed-loop control circuit is formed by negative feedback operational amplifier 12, NPN transistor 21 and sampling resistor 22, so that NPN transistor 21 is in a constant current state to drive LED beads 3 with constant current, thereby eliminating the flickering of lamps under traditional PWM control and realizing stable lighting of lamps.

[0022] Furthermore, the negative feedback operational amplifier 12, the NPN transistor 21, and the sampling resistor 22 form a closed-loop control circuit, which keeps the NPN transistor 21 in a constant current state to drive the LED bead 3 with constant current.

[0023] In this embodiment of the invention, a closed-loop control circuit is formed by negative feedback operational amplifier 12, NPN transistor 21 and sampling resistor 22, so that NPN transistor 21 is in a constant current state to drive LED beads 3 with constant current, thereby eliminating the flickering of lamps under traditional PWM control and realizing stable lighting of lamps.

[0024] Furthermore, the constant current output method greatly enhances the stability of the lamp, completely suppresses the ripple interference of the DC-DC power supply, and ensures the normal operation of the lamp under various power supply environments.

[0025] Furthermore, by designing an external high-power NPN transistor 21 on the LED power board 2, not only is the size of the MCU main control board 1 saved, making installation and layout easier, but the space of the LED power board 2 is also used to set up a dedicated heat dissipation structure, which improves the heat dissipation performance of the transistor and extends its service life.

[0026] Furthermore, the negative feedback operational amplifier 12 is designed on the MCU main control board 1 and shares a power supply with the main control MCU 11, which simplifies the area of ​​the LED power supply board 2 and the power supply system, and reduces the overall cost.

[0027] Furthermore, when it is necessary to adjust the brightness of LED beads 3, the brightness of the LED can be changed synchronously and smoothly by simply adjusting the output voltage of the DAC through the main control MCU11. The dimming process is precise and smooth, improving the user experience.

[0028] Furthermore, the main control MCU11 can also integrate Bluetooth Mesh and microwave radar functions, realizing intelligent control of the lamps, meeting the lighting needs of different scenarios, and improving the practicality and convenience of the lamps.

[0029] Optionally, the temperature compensation circuit 13 includes a diode array 131 and a grounding resistor 132. The DAC output pin of the main control MCU 11 is connected to the positive input of the negative feedback operational amplifier 12 through the diode array 131, and the cathode of the diode array 131 is grounded through the grounding resistor 132.

[0030] When the ambient temperature rises, the voltage on the diode array 131 decreases, which in turn causes the voltage fed back to the positive input of the negative feedback operational amplifier 12 to rise.

[0031] For example, at normal room temperature, the forward voltage VF of this germanium diode is approximately 0.3V, and two diodes in series have a voltage of 0.6V. If the MCU's DAC output is 2V, the voltage input to the positive input of the op-amp is 2V - 0.6V = 1.4V. When the temperature rises, for example by 50 degrees Celsius, the diode's VF voltage drop is approximately 0.15V, and two diodes in series have a voltage of 0.3V. At this point, the voltage at the positive input of the op-amp becomes 2V - 0.3V = 1.7V. Because the diode's temperature coefficient is controllable and reliable, it ensures that the LED operates reliably while being compensated, without requiring additional MCU functionality to measure the LED current and ambient temperature. The entire process becomes very simple and reliable. The only work the MCU software needs to do is increase the drive voltage of the LED by 0.6V to offset the effect of adding the series diode array. Adding a grounding resistor next to the temperature compensation diode appropriately increases the current, ensuring more stable diode operation.

[0032] Because the diode array is mounted on the MCU control board, changes in the diodes essentially reflect changes in the ambient temperature of the lamp. This solution is simple, reliable, and flexible in adjustment, and has achieved good results in testing and practical use.

[0033] Furthermore, when the current across the sampling resistor is insufficient, the voltage across it will decrease. This voltage is fed back to the negative input of the negative feedback op-amp, which will automatically increase its output voltage, increase the base current of the external high-power NPN transistor, thereby increasing the emitter current and maintaining the stability of the output current.

[0034] Optionally, the diode array 131 includes a plurality of diodes connected in series. The specific number of diodes is not limited in this invention.

[0035] Optionally, the temperature compensation circuit 13 includes a first resistor 133, a second resistor 134, a third resistor 135, a fourth resistor 136, and a positive temperature coefficient thermistor 137.

[0036] The DAC output pin of the main control MCU11 is connected to the input terminal of the first resistor 133, the output terminal of the first resistor 133 is connected to the input terminal of the second resistor 134, and the output terminal of the second resistor 134 is connected to the positive input of the negative feedback op-amp 12.

[0037] The output terminal of the second resistor 134 is connected to the input terminals of the third resistor 135 and the fourth resistor 136 respectively. The output terminal of the fourth resistor 136 is connected to the input terminal of the positive temperature coefficient thermistor 137. The output terminals of the third resistor 135 and the output terminals of the positive temperature coefficient thermistor 137 are both grounded.

[0038] When the ambient temperature rises, the resistance of the positive temperature coefficient thermistor 137 increases, which in turn increases the voltage fed back to the positive input of the negative feedback operational amplifier 12.

[0039] In this embodiment of the invention, by combining a positive temperature coefficient thermistor with a resistor network, the temperature compensation circuit can automatically adjust the voltage input to the positive input terminal of the negative feedback operational amplifier 12 according to changes in ambient temperature. When the temperature rises, the resistance of the thermistor increases, thereby increasing the feedback voltage. This design can effectively compensate for the influence of temperature changes on the LED drive current, maintain stable LED brightness, avoid overcompensation or excessive current, prevent LED aging, improve system reliability, simplify hardware design, and reduce costs by not relying on complex temperature sensors.

[0040] Optionally, the main control MCU11 controls the NPN transistor 21 through the DAC output.

[0041] Specifically, the main control MCU11 outputs a precise control voltage signal through its built-in DAC (digital-to-analog converter). This voltage signal, after passing through a temperature compensation circuit, is transmitted to the positive input of the negative feedback operational amplifier 12, thereby adjusting the negative feedback loop. When the DAC voltage output by the MCU changes, the negative feedback operational amplifier 12 adjusts its output voltage according to the change in input voltage, thereby controlling the base current of the external high-power NPN transistor 21. The NPN transistor 21 adjusts its emitter current according to the change in base current, thus precisely controlling the current of the LED bead 3 and achieving LED brightness adjustment. This constant current driving method ensures stable brightness of the LED bead under different operating conditions.

[0042] Optionally, a heat dissipation structure matching the NPN transistor 21 is provided on the LED power board 2.

[0043] It's important to note that the NPN transistor 21 consumes power during operation, meaning it generates heat. If this heat isn't effectively dissipated, the performance of the NPN transistor 21 may be affected, or even damaged. Therefore, matching the heat dissipation structure to the NPN transistor 21 during the design phase is crucial. The purpose of the heat dissipation structure is to quickly remove the heat generated by the transistor, ensuring that the NPN transistor 21 operates within its normal temperature range and preventing performance degradation or malfunction due to overheating. The design of the heat dissipation structure considers the transistor's power consumption and heat distribution, typically using heat sinks to increase the heat conduction area, improve heat dissipation efficiency, and thus extend the device's lifespan.

[0044] Optionally, the heat dissipation structure is specifically a heat sink. A heat sink is a common type of heat dissipation structure; it improves heat dissipation efficiency by increasing the surface area. Heat sinks are typically made of highly thermally conductive materials such as aluminum alloy, and through contact with the NPN transistor 21, they rapidly conduct the heat generated by the transistor away. The design of the heat sink usually takes into account the power requirements of the LED luminaire, space constraints, and environmental conditions. For example, designing a dedicated heat sink for the NPN transistor 21 on the LED power board 2 not only ensures that the transistor's temperature remains within a safe range but also improves the overall thermal management performance of the LED power board, preventing performance degradation or failure due to overheating.

[0045] Optionally, the bandwidth of the negative feedback operational amplifier 12 is not less than 1MHz. The negative feedback operational amplifier 12 is the core component of the entire constant current drive circuit, responsible for regulating and stabilizing the LED current. To ensure stability while maintaining a high-speed response, the operational amplifier's bandwidth must be sufficiently wide. A bandwidth of not less than 1MHz means that the negative feedback operational amplifier 12 can handle rapidly changing signals, ensuring the system's response speed and accuracy. The wider the bandwidth, the larger the range of signal frequencies that the negative feedback operational amplifier 12 can handle, which is crucial for the stability of the constant current control circuit. The high-bandwidth negative feedback operational amplifier 12 can effectively suppress current fluctuations caused by factors such as power supply noise and load changes, thereby ensuring that the brightness of the LED bead 3 remains stable and avoiding flickering or fluctuations.

[0046] Optionally, the MCU main control board 1 also includes a sensor interface for acquiring sensor data and a communication interface for communication. The sensor interface can connect to ambient light sensors, temperature sensors, etc., for real-time acquisition of environmental data. For example, the ambient light sensor can adjust the LED brightness according to the ambient light intensity, achieving automatic dimming. The temperature sensor can monitor the internal temperature of the lamp and adjust the drive current in real time to prevent overheating. Furthermore, communication interfaces such as Bluetooth, Wi-Fi, or Zigbee enable remote control and data transmission between the lamp and smart home systems or mobile devices. By integrating these functions, the MCU can not only control brightness but also achieve intelligent management of the lamp, improving user experience and device adaptability.

[0047] Optionally, sampling resistor 22 is grounded. Grounding sampling resistor 22 helps ensure the stability of the current monitoring signal and reduces interference. By grounding the sampling resistor, the entire measurement signal can be measured at a lower potential, making the system more stable and reducing current measurement errors caused by ground noise and other issues.

[0048] This utility model encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of this utility model. To provide the public with a thorough understanding of this utility model, specific details are described in detail in the preferred embodiments; however, those skilled in the art can fully understand this utility model without these details. Furthermore, to avoid unnecessary confusion regarding the essence of this utility model, well-known methods, processes, procedures, components, and circuits are not described in detail.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present utility model, and not to limit it. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present utility model. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present utility model should be included within the protection scope of the present utility model.

Claims

1. A smart lighting fixture based on constant current drive, characterized in that, include: MCU main control board (1) and LED power supply board (2); the MCU main control board (1) is equipped with a main control MCU (11) with DAC output function, a negative feedback operational amplifier (12) and a temperature compensation circuit (13); the LED power supply board (2) is equipped with an external high-power NPN transistor (21), a sampling resistor (22) and a power conversion circuit (23) for converting AC input power into LED driving voltage; the LED power supply board (2) drives LED beads (3) through the power conversion circuit (23); the DAC output pin of the main control MCU (11) is connected to the positive input of the negative feedback operational amplifier (12) through the temperature compensation circuit (13), the output of the negative feedback operational amplifier (12) is connected to the base of the NPN transistor (21), the sampling resistor (22) and the negative input of the negative feedback operational amplifier (12) are both connected to the emitter of the NPN transistor (21), and the LED beads (3) are connected to the collector of the NPN transistor (21); The negative feedback operational amplifier (12), the NPN transistor (21) and the sampling resistor (22) form a closed-loop control circuit, so that the NPN transistor (21) is in a constant current state to drive the LED bead (3) with constant current.

2. The intelligent lighting fixture based on constant current drive according to claim 1, characterized in that, The temperature compensation circuit (13) includes a diode array (131) and a grounding resistor (132); the DAC output pin of the main control MCU (11) is connected to the positive input of the negative feedback operational amplifier (12) through the diode array (131), and the cathode of the diode array (131) is grounded through the grounding resistor (132); When the ambient temperature rises, the voltage on the diode array (131) decreases, which in turn causes the voltage fed back to the positive input of the negative feedback operational amplifier (12) to rise.

3. The intelligent lighting fixture based on constant current drive according to claim 2, characterized in that, The diode array (131) includes multiple diodes connected in series.

4. The intelligent lighting fixture based on constant current drive according to claim 1, characterized in that, The temperature compensation circuit (13) includes a first resistor (133), a second resistor (134), a third resistor (135), a fourth resistor (136), and a positive temperature coefficient thermistor (137). The DAC output pin of the main control MCU (11) is connected to the input terminal of the first resistor (133), the output terminal of the first resistor (133) is connected to the input terminal of the second resistor (134), and the output terminal of the second resistor (134) is connected to the positive input of the negative feedback operational amplifier (12). The output terminal of the second resistor (134) is connected to the input terminals of the third resistor (135) and the fourth resistor (136) respectively. The output terminal of the fourth resistor (136) is connected to the input terminal of the positive temperature coefficient thermistor (137). The output terminals of the third resistor (135) and the positive temperature coefficient thermistor (137) are both grounded. When the ambient temperature rises, the resistance of the positive temperature coefficient thermistor (137) increases, which in turn increases the voltage fed back to the positive input of the negative feedback operational amplifier (12).

5. The intelligent lighting fixture based on constant current drive according to claim 1, characterized in that, The main control MCU (11) controls the NPN transistor (21) through DAC output.

6. The intelligent lighting fixture based on constant current drive according to claim 1, characterized in that, The LED power board (2) is provided with a heat dissipation structure that matches the NPN transistor (21).

7. The intelligent lighting fixture based on constant current drive according to claim 6, characterized in that, The heat dissipation structure is specifically a heat sink.

8. The intelligent lighting fixture based on constant current drive according to claim 1, characterized in that, The bandwidth of the negative feedback operational amplifier (12) is not less than 1MHz.

9. The intelligent lighting fixture based on constant current drive according to claim 1, characterized in that, The MCU main control board (1) is also equipped with a sensor interface for realizing sensor data acquisition and a communication interface for communication.

10. The intelligent lighting fixture based on constant current drive according to claim 1, characterized in that, The sampling resistor (22) is grounded.

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