Table lamp power supply

Abstract

The utility model relates to the technical field of power supplies, and discloses a desk lamp power supply, which aims to solve the technical problem that glasses are uncomfortable due to flicker caused by PWM (Pulse-Width Modulation) dimming adopted in the conventional desk lamp, and is provided with a reference power supply circuit, a dimming circuit and a driving circuit, the rectification module is used for providing a direct-current power supply for the reference power supply circuit, the dimming circuit and the driving circuit, the reference power supply circuit is used for providing reference voltage for the dimming circuit, the dimming circuit is used for controlling the output current of the driving circuit, and the driving circuit supplies power to the LED assembly; the dimming circuit comprises a reference potentiometer CW and an operational amplifier U15, the in-phase input end of the operational amplifier U15 is connected with the adjusting end through a resistor R77, the first fixed end of the reference potentiometer CW is grounded, the second fixed end of the reference potentiometer CW is connected with the reference power supply circuit through a resistor R79, the inverted input end of the operational amplifier U15 is grounded through a capacitor C30, and the output end of the operational amplifier U15 is connected with the driving circuit. PWM dimming is not adopted, so that the stroboflash problem is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of power supplies, in particular to a desk lamp power supply. Background Art

[0002] As people's awareness of quality of life and health continues to improve, LED (Light Emitting Diode) desk lamps are gradually replacing traditional energy-saving desk lamps and becoming widely used lighting equipment. LED desk lamps are favored for their excellent energy-saving effects and extremely long service life.

[0003] For example, the Chinese invention patent application document with publication number CN105357815A discloses an LED desk lamp, which includes a power adapter circuit, a PWM dimming integrated circuit, a light source driving circuit and an LED quantum dot light source, as shown in pages

[0004] to

[0006] of its specification; the power adapter circuit is connected to the input end of the PWM dimming integrated circuit; the output end of the PWM dimming integrated circuit is connected to the LED quantum dot light source through the light source driving circuit, and the turning on, off and brightness of the LED quantum dot light source are controlled by the PWM dimming integrated circuit and the light source driving circuit.

[0004] However, users have higher and higher requirements for the light quality of desk lamps. Existing desk lamps use PWM dimming, which is a common LED dimming technology, but it has some disadvantages. The first is the flickering problem, which may cause eye discomfort or even harm health after long-term use. Second, PWM dimming may generate electromagnetic interference and noise, affecting user experience and other devices. Utility Model Content

[0005] The utility model aims to provide a desk lamp power supply to solve the technical problem that PWM dimming is used in existing desk lamps and flickers, causing discomfort to glasses.

[0006] To achieve the above purpose, the specific technical solution of a desk lamp power supply of the utility model is as follows:

[0007] A desk lamp power supply comprises a step-down circuit and a rectifier module. The step-down circuit comprises a transformer T2. The primary side of the transformer T2 is input with AC power. The secondary side of the transformer T2 is connected to the input end of the rectifier module. A reference power supply circuit, a dimming circuit and a drive circuit are provided. The rectifier module is used to provide a DC power supply to the reference power supply circuit, the dimming circuit and the drive circuit. The reference power supply circuit is used to provide a reference voltage to the dimming circuit. The dimming circuit is used to control the output current of the drive circuit. The drive circuit supplies power to an LED component. The dimming circuit comprises a reference potentiometer CW and an operational amplifier U15. The in-phase input end of the operational amplifier U15 is connected to the adjustment end through a resistor R77. The first fixed end of the reference potentiometer CW is grounded. The second fixed end of the reference potentiometer CW is connected to the reference power supply circuit through a resistor R79. The inverting input end of the operational amplifier U15 is grounded through a capacitor C30. The output end of the operational amplifier U15 is connected to the drive circuit.

[0008] The key technology of the desk lamp power supply lies in the design of its dimming circuit, which uses a reference potentiometer CW and an op amp U15. The reference potentiometer CW is connected to the reference power circuit through resistor R79, ensuring that the dimming circuit can obtain a stable reference voltage. The inverting input of the op amp U15 is grounded through capacitor C30, thereby providing a stable reference level, allowing the circuit to accurately control the output of the LED component at different brightnesses. The output of the op amp U15 is connected to the drive circuit, which is responsible for adjusting the current of the LED component, thereby realizing the dimming function of the desk lamp. Overall, this design can ensure that the LED desk lamp can provide stable and continuous lighting effects at different brightnesses, and does not use PWM dimming, thereby avoiding frequent flickering problems and improving the user experience and visual comfort.

[0009] Furthermore, the reference power supply circuit includes an operational amplifier regulator Z1 and an operational amplifier U16, the non-inverting input terminal of the operational amplifier U16 is connected to the cathode of the voltage regulator Z1, the anode of the voltage regulator Z1 is grounded, the inverting input terminal of the operational amplifier U16 is connected to its output terminal, the output terminal of the operational amplifier U16 is grounded through a capacitor C31, and the operational amplifier U16 is connected to the anode of the diode D14 through a pull-up resistor R80.

[0010] The operational amplifier regulator Z1 can provide a stable voltage. Regardless of the fluctuation of the mains input, the reference power supply circuit can provide a consistent reference voltage, thus ensuring the stability of the dimming circuit.

[0011] The operational amplifier U16 achieves high-precision regulation of the output voltage of the voltage regulator Z1 through a negative feedback mechanism. By connecting the inverting input terminal to the output terminal, the voltage deviation can be reduced, thereby improving the stability and accuracy of the circuit.

[0012] The output end of the operational amplifier U16 is grounded through the capacitor C31, which can effectively suppress voltage fluctuations and further improve the stability and noise suppression capability of the circuit.

[0013] The above characteristics of the reference power supply circuit can ensure that the power supply circuit provides a stable reference voltage with high accuracy and stability, thereby providing a reliable basis for the dimming circuit and further ensuring the stable lighting effect of the LED desk lamp at different brightness.

[0014] Furthermore, the driving circuit includes a PNP-type power transistor Q7 and an NPN-type power transistor Q8, the base of the power transistor Q8 is connected to the output end of the operational amplifier U15 through a resistor R74, the emitter of the power transistor Q8 is grounded, the collector of the power transistor Q8 is connected to the base of the power transistor Q7 through a resistor R81, and the collector of the power transistor Q7 outputs a regulated power supply to the LED through an energy storage inductor L2.

[0015] The bipolar structure using PNP and NPN power transistors can achieve more efficient current control. The NPN power transistor Q8 controls the base voltage of Q7, thereby controlling the brightness of the LED, while Q7 is responsible for outputting the power current to the LED component.

[0016] The circuit can provide a stable current output by outputting a regulated power supply to the LED through the collector of the power transistor Q7 via the energy storage inductor L2.

[0017] The output structure of the energy storage inductor L2 can effectively convert the power supply current into the stable current required by the LED. The output end of the resistor R74 and the operational amplifier U15 is connected to the base of the power transistor Q8, realizing precise control of the LED output current. It can ensure the stable lighting effect of the LED at different brightness and avoid the problem of frequent flickering.

[0018] Furthermore, a diode D12 is provided, the collector of the power transistor Q7 is connected to the cathode of the diode D12, the anode of the diode D12 is grounded, and a resistor R82 is connected between the base and emitter of the power transistor Q7.

[0019] The setting of diode D12 can realize reverse protection and prevent the circuit from being damaged by reverse voltage. This design ensures the stability and reliability of the circuit, improves the durability of the circuit, and prolongs the service life of the desk lamp.

[0020] When reverse voltage appears in the circuit, diode D12 will conduct and guide the reverse current to the ground, preventing the reverse current from damaging other components in the circuit. This design protects other components in the drive circuit and ensures the stable operation of the entire power supply circuit.

[0021] The setting of resistor R82 can help control the current between the base and emitter of power transistor Q7, further improving the stability of the circuit and the accuracy of current control. This helps to ensure that the LED components obtain stable current output, thereby ensuring the stable lighting effect of the LED desk lamp at different brightness and reducing the possibility of frequent flickering.

[0022] The setting of diode D12 and resistor R82 improves the stability and reliability of the circuit, while protecting other components from the influence of reverse voltage, ensuring the stable lighting effect of the LED desk lamp and reducing the possibility of frequent flickering.

[0023] The desk lamp power supply provided by the utility model has the following advantages:

[0024] The dimming circuit uses a reference potentiometer CW and an op amp U15. The reference potentiometer CW is connected to the reference power supply circuit through resistor R79, ensuring that the dimming circuit can obtain a stable reference voltage. The inverting input of the op amp U15 is grounded through capacitor C30, thereby providing a stable reference level, allowing the circuit to accurately control the output of the LED component at different brightnesses. The output of the op amp U15 is connected to the drive circuit, which is responsible for adjusting the current of the LED component, thereby realizing the dimming function of the desk lamp. Overall, this design can ensure that the LED desk lamp can provide stable and continuous lighting effects at different brightnesses, and does not use PWM dimming, thereby avoiding frequent flickering problems and improving the user experience and visual comfort. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a functional structure diagram of the desk lamp power supply provided by the utility model;

[0026] Figure 2 The utility model provides a power supply schematic diagram of the desk lamp. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0028] See also Figure 1 and Figure 2The utility model provides a desk lamp power supply, including a step-down circuit, a rectifier module, a reference power supply circuit, a dimming circuit and a drive circuit. The step-down circuit includes a transformer T2. The primary side of the transformer T2 is input with AC power. The secondary side of the transformer T2 is connected to the input end of the rectifier module. The rectifier module is used to provide a DC power supply V+ to the reference power supply circuit, the dimming circuit and the drive circuit. The reference power supply circuit is used to provide a reference voltage to the dimming circuit. The dimming circuit is used to control the output current of the drive circuit. The drive circuit supplies power to the LED component.

[0029] The input end of the transformer T2 is connected to the live wire L and the neutral wire N, and the output end of the transformer T2 is connected to a rectifier module, which includes a diode D13, a diode D14, a diode D15 and a diode D16. The anodes of the diode D13 and the diode D15 are connected, the cathodes of the diode D14 and the diode D16 are connected, the cathode of the diode D15 is connected to the anode of the diode D16, the anode of the diode D14 is connected to the cathode of the diode D13, and the anode of the diode D15 and the anode of the diode D14 are respectively connected to the output end of the transformer T2. The anode of the diode D13 is grounded as the negative electrode of the rectifier output end, the cathode of the diode D14 and the cathode of the diode D16 are used as the positive electrode of the rectifier output end, and the positive electrode of the rectifier output end is connected to the filter capacitor C33.

[0030] The AC power outputs a 12V to 15V DC power supply V+ through transformer T2 and rectifier module.

[0031] The reference power supply circuit includes an operational amplifier regulator Z1 and an operational amplifier U16, the non-inverting input terminal of the operational amplifier U16 is connected to the cathode of the voltage regulator Z1, the anode of the voltage regulator Z1 is grounded, the inverting input terminal of the operational amplifier U16 is connected to its output terminal, the output terminal of the operational amplifier U16 is grounded through a capacitor C31, and the operational amplifier U16 is connected to the anode of the diode D14 through a pull-up resistor R80.

[0032] The power supply of the operational amplifier U16 is taken from the DC power supply V+ output by the rectifier module. The operational amplifier U16 and the voltage regulator Z1 constitute a reference power supply circuit for providing a reference voltage to the operational amplifier U15.

[0033] The non-inverting input terminal of the operational amplifier U15 is connected to the adjustment terminal of the reference potentiometer CW through a resistor R77. The reference potentiometer CW includes a first fixed terminal, a second fixed terminal and an adjustment terminal. The first fixed terminal of the reference potentiometer CW is grounded. The second fixed terminal of the reference potentiometer CW is connected to the output terminal of the operational amplifier U16 through a resistor R79. A resistor R75 is connected between the output terminal of the operational amplifier U15 and its non-inverting input terminal. The inverting input terminal of the operational amplifier U15 is grounded through a capacitor C30.

[0034] A PNP-type power transistor Q7 and an NPN-type power transistor Q8 are provided. The base of the power transistor Q8 is connected to the output terminal of the operational amplifier U15 through a resistor R74, the emitter of the power transistor Q8 is grounded, the collector of the power transistor Q8 is connected to the base of the power transistor Q7 through a resistor R81, the emitter of the power transistor Q7 is connected to the DC power supply V+, and the collector of the power transistor Q7 outputs a voltage-stabilized power supply to the LED through the energy storage inductor L2. A diode D12 is also provided, the collector of the power transistor Q7 is connected to the cathode of the diode D12, and the anode of the diode D12 is grounded. A resistor R82 is connected between the base and the emitter of the power transistor Q7. The diode D12 is used as a freewheeling diode and is combined with the energy storage inductor L2 to make the output power supply more stable.

[0035] In one embodiment, the inductor L1 is a high-frequency magnetic ring with an outer diameter of 15 mm, and the diameter of the enameled wire is 0.25 mm.

[0036] The LED assembly is grounded through the current detection resistor R83, and is also connected to the inverting input of the operational amplifier U15 through the feedback resistor R78. The inverting input of the operational amplifier U15 is sampled by the detection resistor R83 and compared with the non-inverting input, so that its output is adjusted by the reference potentiometer CW, and is driven and amplified by the power transistors Q7 and Q8 to light up the LED.

[0037] In one embodiment, the power of the current-sense resistor R83 is 1W and the resistance is 2.2 ohms, which determines the total current of the LED light-emitting component.

[0038] The reference potentiometer can control the output current of the subsequent stage to complete the dimming. The PWM adjustment method is not adopted, and there is no flicker problem in this dimming.

[0039] In summary, the utility model provides a desk lamp power supply, and the dimming circuit adopts a reference potentiometer CW and an operational amplifier U15. The reference potentiometer CW is connected to the reference power supply circuit through a resistor R79, ensuring that the dimming circuit can obtain a stable reference voltage. The inverting input terminal of the operational amplifier U15 is grounded through a capacitor C30, thereby providing a stable reference level, so that the circuit can accurately control the output of the LED component at different brightnesses. The output terminal of the operational amplifier U15 is connected to the driving circuit, which is responsible for adjusting the current of the LED component, thereby realizing the dimming function of the desk lamp. Overall, this design can ensure that the LED desk lamp can provide stable and continuous lighting effects at different brightnesses, and PWM dimming is not used, thereby avoiding frequent flickering problems and improving the user experience and visual comfort.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A desk lamp power supply, comprising a step-down circuit and a rectifier module, wherein the step-down circuit comprises a transformer T2, the primary side of the transformer T2 is input with AC power, and the secondary side of the transformer T2 is connected to the input end of the rectifier module, characterized in that: A reference power supply circuit, a dimming circuit and a driving circuit are provided. The rectifier module is used to provide a DC power supply to the reference power supply circuit, the dimming circuit and the driving circuit. The reference power supply circuit is used to provide a reference voltage to the dimming circuit. The dimming circuit is used to control the output current of the driving circuit. The driving circuit supplies power to the LED component. The dimming circuit includes a reference potentiometer CW and an operational amplifier U15. The in-phase input terminal of the operational amplifier U15 is connected to the adjustment terminal through a resistor R77. The first fixed terminal of the reference potentiometer CW is grounded. The second fixed terminal of the reference potentiometer CW is connected to the reference power supply circuit through a resistor R79. The inverting input terminal of the operational amplifier U15 is grounded through a capacitor C30. The output terminal of the operational amplifier U15 is connected to the driving circuit.

2. A desk lamp power supply according to claim 1, characterized in that: The reference power supply circuit includes an operational amplifier regulator Z1 and an operational amplifier U16, wherein the non-inverting input terminal of the operational amplifier U16 is connected to the cathode of the voltage regulator Z1, the anode of the voltage regulator Z1 is grounded, the inverting input terminal of the operational amplifier U16 is connected to its output terminal, the output terminal of the operational amplifier U16 is grounded via a capacitor C31, and the operational amplifier U16 is connected to the anode of the diode D14 via a pull-up resistor R80.

3. A desk lamp power supply according to claim 2, characterized in that: The driving circuit includes a PNP type power transistor Q7 and an NPN type power transistor Q8. The base of the power transistor Q8 is connected to the output end of the operational amplifier U15 through a resistor R74, the emitter of the power transistor Q8 is grounded, the collector of the power transistor Q8 is connected to the base of the power transistor Q7 through a resistor R81, and the collector of the power transistor Q7 outputs a regulated power supply to the LED through an energy storage inductor L2.

4. A desk lamp power supply according to claim 3, characterized in that: A diode D12 is also provided. The collector of the power transistor Q7 is connected to the cathode of the diode D12. The anode of the diode D12 is grounded. A resistor R82 is connected between the base and emitter of the power transistor Q7.

Images