Head-mounted LED operating shadowless lamp circuit and head-mounted LED operating shadowless lamp

Abstract

The invention discloses a head-mounted LED operating shadowless lamp circuit and a head-mounted LED operating shadowless lamp, and belongs to the technical field of medical instruments. The circuit comprises an LED direct current driving chip, a voltage sampling resistor, a current sampling resistor, a soft start capacitor, an external MOS tube and LED lamp beads connected in parallel. A soft start circuit, a power taking circuit, a reference voltage circuit, a voltage constant circuit, a comparison amplification circuit, a current constant circuit and a control output circuit are arranged in the LED direct-current driving chip, constant-voltage, constant-power or constant-current driving can be achieved, PWM dimming is not needed, and therefore the stroboflash phenomenon is thoroughly eliminated, and lighting uniformity and visual comfort are improved. The device is simple in structure, high in integration level, good in reliability and suitable for fine operation occasions such as surgical operations.

Description

Technical Field

[0001] This invention belongs to the field of medical device technology and relates to a head-mounted LED surgical shadowless lamp circuit and a head-mounted LED surgical shadowless lamp. Background Technology

[0002] Head-mounted LED surgical shadowless lamps are crucial equipment in surgical procedures, as their illumination directly affects the clarity of the surgical field and the precision of the surgeon's operation. Ordinary head-mounted LED surgical shadowless lamps are powered by lithium batteries and dimmed via a PWM-controlled DC / DC module. While they offer advantages such as portability and dimming capability, they still have the following drawbacks: 1) They require the integration of lithium battery management, DC / DC conversion, PWM control, and protection circuits, increasing PCB layout complexity and potential failure points; 2) At low PWM frequencies (e.g., below 200Hz), visible flicker occurs, causing visual fatigue or illusions for the surgeon, affecting the precision of surgical operations. While high-frequency PWM (e.g., >1kHz) can alleviate flicker, it increases switching losses and electromagnetic interference. Summary of the Invention

[0003] The technical solution of this invention is used to solve the problem of how to design a simple, flicker-free head-mounted LED surgical shadowless lamp circuit.

[0004] The present invention solves the above-mentioned technical problems through the following technical solutions: This invention provides a head-mounted LED surgical shadowless lamp circuit, comprising: an LED DC driver chip U1, a voltage sampling resistor Rf, a current sampling resistor Rs, a soft-start capacitor Cp, an external MOSFET, and multiple LED beads; the multiple LED beads are connected in parallel to form an LED lighting module, and the positive terminal of the LED lighting module is connected to the 8V pin of the LED DC driver chip U1. # The pin is connected in parallel to the positive terminal of the lithium battery, and one end of the voltage sampling resistor Rf is connected to the 8 pin of the LED DC driver chip U1. # Pin connections: the other end of the voltage sampling resistor Rf is connected to pin 7 of the LED DC driver chip U1. # Pin connections: One end of the soft-start capacitor Cp is connected to pin 2 of the LED DC driver chip U1. # Pin connections: the other end of the soft-start capacitor Cp is connected to pin 1 of the LED DC driver chip U1. # Pin connections, LED DC driver chip U1's pin 1 # The pin is grounded, and the gate of the external MOSFET is connected to pin 5 of the LED DC driver chip U1. # Pin connections: The source of the external MOSFET is connected to one end of the current sampling resistor Rs. The source of the external MOSFET is also connected to pin 3 of the LED DC driver chip U1. #Pin connections are established, the other end of the current sampling resistor Rs is grounded, the drain of the external MOSFET is connected to the negative terminal of the LED lighting module, and the LED DC driver chip U1 has four pins connected to the ground. # pins and 6 # All pins are left floating.

[0005] Further, the LED DC driver chip U1 includes: a power supply circuit, a reference voltage circuit, a voltage constant circuit, a comparator amplifier circuit, a current constant circuit, a control output circuit, and a soft-start circuit; the soft-start circuit is connected to the power supply circuit, which is connected to the voltage constant circuit, the reference voltage circuit, and the current constant circuit respectively; the comparator amplifier circuit is connected to the voltage constant circuit, the reference voltage circuit, the current constant circuit, and the control output circuit respectively; the power supply circuit obtains the power for chip operation from an external circuit; the comparator amplifier circuit compares and amplifies the voltage signals collected by the voltage sampling resistor Rf and the current sampling resistor Rs with the reference voltage; the voltage constant circuit, when the external power supply voltage is higher than the rated voltage, compares and amplifies the voltage signals collected by the voltage sampling resistor Rf and the current sampling resistor Rs with the reference voltage; the voltage constant circuit, when the external power supply voltage is higher than the rated voltage, compares and amplifies the voltage signals collected by the voltage sampling resistor Rf and the current sampling resistor Rs with the reference voltage; The comparator amplifier circuit and output control circuit adjust the operating state of the external MOSFET, allowing the external MOSFET to handle the overvoltage portion and enabling the LED lighting module to operate in a constant voltage state. When the external power supply voltage is lower than the rated voltage, the comparator amplifier circuit and output control circuit adjust the operating state of the external MOSFET to ensure it is fully turned on, enabling the LED lighting module to operate in a constant power state. The current constant circuit collects the current of the LED lighting module and adjusts the operating state of the external MOSFET through the comparator amplifier circuit and output control circuit, enabling the LED lighting module to operate in a constant current state. The control output circuit controls the operating state of the external MOSFET, enabling the LED lighting module to operate in constant voltage, constant power, or constant current modes.

[0006] Furthermore, the power supply circuit includes: a resistor R1 and a transistor W1; one end of the resistor R1 serves as the F port of the LED DC driver chip U1, and the other end of the resistor R1 is connected to the emitter of the transistor W1. The base and collector of the transistor W1 are shorted and then grounded, and the grounded end serves as the B port of the LED DC driver chip U1. At this time, the transistor W1 is used as a Zener diode.

[0007] Further, the reference voltage circuit includes: transistor T2, resistor R5, transistor D1, transistor D2, transistor D3, transistor T5, and transistor T6; the collector of transistor T2 is connected to one end of resistor R1, the base of transistor T2 is connected to the other end of resistor R1, the emitter of transistor T2 is connected to one end of resistor R5, the other end of resistor R5 is connected to the base of transistor D1, and the base and collector of transistor D1 are short-circuited. In this case, transistor D1 functions as a diode. The emitter of transistor D2 is connected to the base of transistor D2, and the base and collector of transistor D2 are shorted. In this case, transistor D2 is used as a diode. The emitter of transistor D2 is connected to the base of transistor D3, and the base and collector of transistor D3 are shorted. In this case, transistor D3 is used as a diode. The emitter of transistor D3 is connected to the base of transistor T5, and the base and collector of transistor T5 are shorted. The emitter of transistor T5 is grounded. The base of transistor T5 is connected to the base of transistor T6, and the emitter of transistor T6 is grounded.

[0008] Further, the voltage constant circuit includes: transistors Q3, Q4, and T3, resistors R2, R6, and R7; the emitter of transistor Q3 is connected to one end of resistor R1, the base of transistor Q3 is connected to the base of transistor Q4, the base and collector of transistor Q3 are short-circuited, the collector of transistor Q3 is connected to the collector of transistor T3, the base of transistor T3 is connected to one end of resistor R6, the other end of resistor R6 is connected to the common point where resistor R5 and transistor D1 are connected, the emitter of transistor T3 is connected to one end of resistor R7, the other end of resistor R7 is connected to the collector of transistor T6, the emitter of transistor Q4 is connected to one end of resistor R1, the collector of transistor Q4 is connected to one end of resistor R2, and the other end of resistor R2 serves as the E port of LED DC driver chip U1.

[0009] Further, the comparison amplifier circuit includes: transistor T4, resistors R8, R10, R11, and R12; the collector of transistor T4 is connected to one end of resistor R1, the emitter of transistor T4 is connected to one end of resistor R8, the other end of resistor R8 is connected to the collector of transistor T6, resistors R11 and R12 are connected in series, wherein the non-series end of resistor R11 is connected to the emitter of transistor T2, and the non-series end of resistor R12 is grounded; the base of transistor T4 is connected to one end of resistor R10, and the other end of resistor R10 is connected to the common point of series connection of resistors R11 and R12.

[0010] Further, the constant current circuit includes: transistor T7, transistor T8, resistors R3, R13, R14, R15, R16, and R17; the collector of transistor T7 is connected to one end of resistor R1, the emitter of transistor T7 is connected to one end of resistor R14, the other end of resistor R14 is connected to one end of resistor R13, the other end of resistor R13 is grounded, and the base of transistor T7 is connected to the common point of series connection of resistors R11 and R12; the collector of transistor T8 is connected to resistor R2... The other end is connected as follows: the emitter of transistor T8 is connected to one end of resistor R15, the other end of resistor R15 is connected to one end of resistor R13, and resistors R3 and R17 are connected in series. The non-series end of resistor R3 is connected to the collector of transistor Q1, and the non-series end of resistor R17 is grounded. The common point of the series connection of resistors R3 and R17 serves as the C port of LED DC driver chip U1. The base of transistor T8 is connected to one end of resistor R16, and the other end of resistor R16 is connected to the common point of the series connection of resistors R3 and R17.

[0011] Furthermore, the control output circuit includes: transistor T9, transistor T10, and resistor R18; the base of transistor T9 is connected to the common point of resistors R11 and R12 in series, the collector of transistor T9 is connected to one end of resistor R1, the emitter of transistor T9 is connected to one end of resistor R18, the base of transistor T10 serves as the D port of LED DC driver chip U1, the collector of transistor T10 is connected to the other end of resistor R2, the emitter of transistor T10 is connected to one end of resistor R18, and the other end of resistor R18 is grounded.

[0012] Furthermore, the soft-start circuit includes: transistor Q1, transistor Q2, resistor R4, and transistor D4; the emitter of transistor Q1 is connected to the emitter of transistor Q2, and then connected to one end of resistor R1; the base of transistor Q1 is connected to the base of transistor Q2; the base and collector of transistor Q2 are short-circuited; the collector of transistor Q2 is connected to one end of resistor R4; the other end of resistor R4 is connected to the other end of resistor R1; the collector of transistor D4 is connected to the emitter of transistor Q2; the base and emitter of transistor D4 are short-circuited, at which point transistor D4 is used as a diode; the base of transistor D4 is connected to the base of transistor T3; and the short-circuited base and emitter of transistor D4 serve as port A of the LED DC driver chip U1.

[0013] The present invention also provides a head-mounted LED surgical shadowless lamp, wherein the head-mounted LED surgical shadowless lamp is powered by the above-mentioned head-mounted LED surgical shadowless lamp circuit.

[0014] The beneficial effects of this invention are as follows: This invention employs an LED DC driver chip to drive LEDs with constant voltage and constant current, completely eliminating PWM dimming and preventing flickering at its source, thus protecting the visual health of users. The integrated LED DC driver chip replaces multi-module discrete designs, reducing external components and lowering PCB layout complexity and failure rate. It avoids high-frequency switching operations, reducing switching losses and electromagnetic interference, and improving system energy efficiency and compatibility. The LED DC driver chip has a built-in soft-start circuit that delays the power-on process, prevents current surges, and extends the lifespan of the LED and components. It can automatically switch between constant voltage, constant power, or constant current modes based on the input voltage, adapting to lithium battery voltage fluctuations and maintaining stable lighting. Within its operating range, the LED current is stable, providing uniform illumination without dark areas or bright spots. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the head-mounted LED surgical shadowless lamp circuit according to Embodiment 1 of the present invention; Figure 2 This is a structural block diagram of the LED DC driver chip according to Embodiment 1 of the present invention; Figure 3 This is a circuit schematic diagram of the LED DC driver chip according to Embodiment 1 of the present invention; Figure 4 This is a PCB diagram of the LED DC driver chip according to Embodiment 1 of the present invention; Figure 5 This is a physical package diagram of the LED DC driver chip according to Embodiment 1 of the present invention. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments: Example 1 like Figure 1 As shown, this embodiment provides a head-mounted LED surgical shadowless lamp circuit, including: an LED DC driver chip U1, a voltage sampling resistor Rf, a current sampling resistor Rs, a soft-start capacitor Cp, an external MOSFET, and multiple LED beads.

[0018] Multiple LED beads are connected in parallel to form an LED lighting module, and the positive terminal of the LED lighting module is connected to the 8-pin LED DC driver chip U1. #The pin is connected in parallel to the positive terminal of the lithium battery, and one end of the voltage sampling resistor Rf is connected to the 8 pin of the LED DC driver chip U1. # Pin connections: the other end of the voltage sampling resistor Rf is connected to pin 7 of the LED DC driver chip U1. # Pin connections: One end of the soft-start capacitor Cp is connected to pin 2 of the LED DC driver chip U1. # Pin connections: the other end of the soft-start capacitor Cp is connected to pin 1 of the LED DC driver chip U1. # Pin connections, LED DC driver chip U1's pin 1 # The pin is grounded, and the gate of the external MOSFET is connected to pin 5 of the LED DC driver chip U1. # Pin connections: The source of the external MOSFET is connected to one end of the current sampling resistor Rs. The source of the external MOSFET is also connected to pin 3 of the LED DC driver chip U1. # Pin connections are established, the other end of the current sampling resistor Rs is grounded, the drain of the external MOSFET is connected to the negative terminal of the LED lighting module, and the LED DC driver chip U1 has four pins connected to the ground. # pins and 6 # All pins are left floating.

[0019] like Figure 2 and Figure 3 As shown, the LED DC driver chip U1 includes: a power supply circuit, a reference voltage circuit, a constant voltage circuit, a comparator amplifier circuit, a constant current circuit, a control output circuit, and a soft start circuit; the soft start circuit is connected to the power supply circuit, the power supply circuit is connected to the constant voltage circuit, the reference voltage circuit, and the constant current circuit respectively, and the comparator amplifier circuit is connected to the constant voltage circuit, the reference voltage circuit, the constant current circuit, and the control output circuit respectively.

[0020] The soft-start circuit includes: PNP transistor Q1, PNP transistor Q2, resistor R4, and NPN transistor D4; the power supply circuit includes: resistor R1 and NPN transistor W1; the reference voltage circuit includes: NPN transistor T2, resistor R5, NPN transistor D1, NPN transistor D2, NPN transistor D3, NPN transistor T5, and NPN transistor T6; the voltage constant circuit includes: PNP transistor Q3, PNP transistor Q4, and NPN transistor D5. 4. NPN transistor T3, resistors R2, R6, and R7; the comparator amplifier circuit includes: NPN transistor T4, resistors R8, R10, R11, and R12; the current constant circuit includes: NPN transistors T7 and T8, resistors R3, R13, R14, R15, R16, and R17; the control output circuit includes: NPN transistors T9 and T10, and resistor R18.

[0021] The emitter of PNP transistor Q1 is connected to the emitter of PNP transistor Q2, and then connected to one end of resistor R1. The base of PNP transistor Q1 is connected to the base of PNP transistor Q2. The base and collector of PNP transistor Q2 are shorted. The collector of PNP transistor Q2 is connected to one end of resistor R4. The other end of resistor R4 is connected to the other end of resistor R1. The collector of NPN transistor D4 is connected to the emitter of PNP transistor Q2. The base and emitter of NPN transistor D4 are shorted. At this time, N... NPN transistor D4 is used as a diode. The base of NPN transistor D4 is connected to the base of NPN transistor T3. The base and emitter of NPN transistor D4 are shorted together and serve as port A of LED DC driver chip U1. One end of resistor R1 serves as port F of LED DC driver chip U1, and the other end of resistor R1 is connected to the emitter of NPN transistor W1. The base and collector of NPN transistor W1 are shorted together and then grounded. The grounded terminal serves as port B of LED DC driver chip U1. At this time, NPN transistor W1 acts as a Zener diode. In the diode configuration, the collector of NPN transistor T2 is connected to one end of resistor R1, the base of NPN transistor T2 is connected to the other end of resistor R1, the emitter of NPN transistor T2 is connected to one end of resistor R5, and the other end of resistor R5 is connected to the base of NPN transistor D1. The base and collector of NPN transistor D1 are shorted, so NPN transistor D1 functions as a diode. The emitter of NPN transistor D1 is connected to the base of NPN transistor D2, and the base and collector of NPN transistor D2 are shorted, so NPN transistor D1 functions as a diode. NPN transistor D2 is used as a diode. The emitter of NPN transistor D2 is connected to the base of NPN transistor D3. The base and collector of NPN transistor D3 are shorted. In this case, NPN transistor D3 is used as a diode. The emitter of NPN transistor D3 is connected to the base of NPN transistor T5. The base and collector of NPN transistor T5 are shorted. The emitter of NPN transistor T5 is grounded. The base of NPN transistor T5 is connected to the base of NPN transistor T6. The emitter of NPN transistor T6 is grounded.The emitter of PNP transistor Q3 is connected to one end of resistor R1. The base of PNP transistor Q3 is connected to the base of PNP transistor Q4. The base and collector of PNP transistor Q3 are shorted. The collector of PNP transistor Q3 is connected to the collector of NPN transistor T3. The base of NPN transistor T3 is connected to one end of resistor R6. The other end of resistor R6 is connected to the common point where resistor R5 and NPN transistor D1 are connected. The emitter of NPN transistor T3 is connected to one end of resistor R7. The other end of resistor R7 is connected to the collector of NPN transistor T6. The emitter of PNP transistor Q4 is connected to one end of resistor R1. The collector of PNP transistor Q4 is connected to... One end of resistor R2 is connected, and the other end of resistor R2 serves as the E port of LED DC driver chip U1; the collector of NPN transistor T4 is connected to one end of resistor R1, the emitter of NPN transistor T4 is connected to one end of resistor R8, and the other end of resistor R8 is connected to the collector of NPN transistor T6; resistors R11 and R12 are connected in series, with the non-series end of resistor R11 connected to the emitter of NPN transistor T2, and the non-series end of resistor R12 grounded; the base of NPN transistor T4 is connected to one end of resistor R10, and the other end of resistor R10 is connected to the common point of series connection of resistors R11 and R12; the collector of NPN transistor T7 is connected to one end of resistor R1. The emitter of NPN transistor T7 is connected to one end of resistor R14, the other end of resistor R14 is connected to one end of resistor R13, and the other end of resistor R13 is grounded. The base of NPN transistor T7 is connected to the common point of series connection of resistors R11 and R12. The collector of NPN transistor T8 is connected to the other end of resistor R2, the emitter of NPN transistor T8 is connected to one end of resistor R15, and the other end of resistor R15 is connected to one end of resistor R13. Resistors R3 and R17 are connected in series. The non-series connection of resistor R3 is connected to the collector of PNP transistor Q1, and the non-series connection of resistor R17 is grounded. The common point of series connection of resistors R3 and R17 serves as the DC current for the LED. At port C of driver chip U1, the base of NPN transistor T8 is connected to one end of resistor R16, and the other end of resistor R16 is connected to the common point of series connection of resistors R3 and R17. The base of NPN transistor T9 is connected to the common point of series connection of resistors R11 and R12. The collector of NPN transistor T9 is connected to one end of resistor R1, and the emitter of NPN transistor T9 is connected to one end of resistor R18. The base of NPN transistor T10 serves as port D of LED DC driver chip U1. The collector of NPN transistor T10 is connected to the other end of resistor R2, and the emitter of NPN transistor T10 is connected to one end of resistor R18. The other end of resistor R18 is grounded.

[0022] like Figure 4 and Figure 5 As shown, the LED DC driver chip U1 is packaged in an SOP8 pin configuration; the pin-to-port correspondence of the LED DC driver chip U1 is as follows: chip 1 # The pin (GND) is port B, which is the common ground terminal; Chip 2 # Pin (SS) is port A, which is the input terminal of the soft-start capacitor; 3 of the chip # Pin (IS) is port C, which is the constant current input terminal; 4 of the chip # The pin (NC) is left floating; 5 of the chip # The OUT pin is the D port, which is the control output terminal; 6 of the chip # The pin (NC) is left floating; 7 of the chip # The pin (VS) is the E port, which is a constant voltage input terminal; 8 of the chip # The pin (VCC) is the F port, which is the power input terminal.

[0023] Working principle description The power supply circuit obtains power from an external circuit, with a low voltage of 3.3V to 5V. The reference voltage circuit generates a reference voltage for the comparator amplifier circuit, with a voltage of approximately 1.2V. The comparator amplifier circuit compares and amplifies the voltage signals collected by the voltage sampling resistor Rf and the current sampling resistor Rs with the reference voltage. The voltage constant circuit adjusts the operating state of the external MOSFET through the comparator amplifier circuit and the output control circuit when the external supply voltage is higher than the rated voltage, so that the external MOSFET bears the overvoltage portion and the LED lighting module operates in a constant voltage state. When the external supply voltage is lower than the rated voltage, the comparator amplifier circuit and the output control circuit adjust the operating state of the external MOSFET to make the external MOSFET fully conduct, so that the LED lighting module operates in a constant power state. The current constant circuit collects the current of the LED lighting module and adjusts the operating state of the external MOSFET through the comparator amplifier circuit and the output control circuit to make the LED lighting module operate in a constant current state. The control output circuit is the chip output section, which controls the operating state of the external MOSFET to make the LED lighting module operate in constant voltage or constant current mode, not exceeding the constant output power.

[0024] The soft-start circuit utilizes the unidirectional conduction of transistor D4. Resistor R4 and soft-start capacitor Cp form an RC time constant. After the RC time constant delay, soft-start capacitor Cp is fully charged, transistors Q2 and Q1 are cut off, and the circuit receives normal power, thus achieving the soft-start function. The NPN transistor W1 in the power supply circuit is reverse-biased, acting as a Zener diode. External power is supplied with a stable circuit voltage through resistor R1 and NPN transistor W1, thus drawing power from an external power source. In the reference voltage circuit, since the conduction voltage of transistors D1, D2, and D3 is... The voltage constant circuit acts as a reference voltage circuit, providing a reference voltage for the LED DC driver chip U1. The voltage constant circuit provides a constant voltage to the LED DC driver chip U1 when the external voltage changes. In the comparison amplification circuit, the input terminal of transistor T4 compares and amplifies externally acquired voltage and current signals, acting as a comparison amplification circuit. The current constant circuit provides a constant current to the LED DC driver chip U1 when the external current changes. The control output circuit amplifies the output through transistors T9 and T10, acting as a control output circuit.

[0025] The operating states of the external MOSFET are as follows: When the external DC power supply voltage is lower than the rated voltage, the external MOSFET is fully turned on. When the external DC power supply voltage exceeds the protection voltage, the external MOSFET is turned off. When the external DC power supply voltage is higher than the rated voltage but lower than the protection voltage, the external MOSFET operates in the linear region. At this time, the voltage division of the external MOSFET can be adjusted by adjusting the impedance of the external MOSFET.

[0026] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention 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. Such 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 invention.

Claims

1. A head-mounted LED surgical shadowless lamp circuit, characterized by, The LED direct current driving chip U1 comprises: a power taking circuit, a reference voltage circuit, a voltage constant circuit, a comparison and amplification circuit, a current constant circuit, a control output circuit and a soft start circuit; the soft start circuit is connected with the power taking circuit, the power taking circuit is connected with the voltage constant circuit, the reference voltage circuit and the current constant circuit respectively, and the comparison and amplification circuit is connected with the voltage constant circuit, the reference voltage circuit, the current constant circuit and the control output circuit respectively; the power taking circuit obtains the power supply for the chip operation from the external circuit, the comparison and amplification circuit compares and amplifies the voltage signals collected by the voltage sampling resistor Rf and the current sampling resistor Rs with the reference voltage; when the external power supply voltage is higher than the rated voltage, the voltage constant circuit adjusts the working state of the external MOS tube through the comparison and amplification circuit and the output control circuit, the external MOS tube bears the overvoltage part, and the LED lighting module works in the constant voltage state; when the external power supply voltage is lower than the rated voltage, the voltage constant circuit adjusts the working state of the external MOS tube through the comparison and amplification circuit and the output control circuit, the external MOS tube is fully turned on, and the LED lighting module works in the constant power state; the current constant circuit adjusts the working state of the external MOS tube through the comparison and amplification circuit and the output control circuit by collecting the current of the LED lighting module, so that the LED lighting module works in the constant current state; the control output circuit controls the working state of the external MOS tube, so that the LED lighting module works in the constant voltage, constant power or constant current mode. LED direct current drive chip U1, voltage sampling resistor Rf, current sampling resistor Rs, soft start capacitor Cp, external MOS tube and a plurality of LED lamp beads; a plurality of said LED lamp beads are connected in parallel to form an LED lighting module, the positive electrode of the LED lighting module is connected with the pin 8 of the LED direct current drive chip U1 # The pin is connected with the positive electrode of the lithium battery, one end of the voltage sampling resistor Rf is connected with the pin 8 of the LED direct current drive chip U1 # The pin is connected, and the other end of the voltage sampling resistor Rf is connected with the pin 7 of the LED direct current drive chip U1 # The pin is connected, and one end of the soft start capacitor Cp is connected with the pin 2 of the LED direct current drive chip U1 # The pin is connected, and the other end of the soft start capacitor Cp is connected with the pin 1 of the LED direct current drive chip U1 # The pin is connected, and the pin 1 of the LED direct current drive chip U1 # The pin is grounded, and the gate electrode of the external MOS tube is connected with the pin 5 of the LED direct current drive chip U1 # The pin is connected, one end of the source electrode of the external MOS tube is connected with the current sampling resistor Rs, and the source electrode of the external MOS tube is also connected with the pin 3 of the LED direct current drive chip U1 # The pin is connected, and the other end of the current sampling resistor Rs is grounded, the drain electrode of the external MOS tube is connected with the negative electrode of the LED lighting module, and the pin 4 of the LED direct current drive chip U1 # The pin and 6 # The pins are all suspended.

2. The head-mounted LED surgical shadowless lamp circuit of claim 1, wherein, The power taking circuit comprises: a resistor R1 and a triode W1; one end of the resistor R1 is used as the F port of the LED direct current driving chip U1, the other end of the resistor R1 is connected with the emitter of the triode W1, the base and the collector of the triode W1 are short-circuited and then grounded, the grounding end is used as the B port of the LED direct current driving chip U1, and the triode W1 is used as a voltage stabilizing diode at this time.

3. The head-mounted LED surgical shadowless lamp circuit of claim 2, wherein, The reference voltage circuit comprises: a triode T2, a resistor R5, a triode D1, a triode D2, a triode D3, a triode T5 and a triode T6; the collector of the triode T2 is connected with one end of the resistor R1, the base of the triode T2 is connected with the other end of the resistor R1, the emitter of the triode T2 is connected with one end of the resistor R5, the other end of the resistor R5 is connected with the base of the triode D1, the base and the collector of the triode D1 are short-circuited, the triode D1 is used as a diode at this time, the emitter of the triode D1 is connected with the base of the triode D2, the base and the collector of the triode D2 are short-circuited, the triode D2 is used as a diode at this time, the emitter of the triode D2 is connected with the base of the triode D3, the base and the collector of the triode D3 are short-circuited, the triode D3 is used as a diode at this time, the emitter of the triode D3 is connected with the base of the triode T5, the base and the collector of the triode T5 are short-circuited, the emitter of the triode T5 is grounded, the base of the triode T5 is connected with the base of the triode T6, and the emitter of the triode T6 is grounded.

4. The head-mounted LED surgical shadowless lamp circuit of claim 3, wherein, ​ 5. The head-mounted LED surgical shadowless lamp circuit of claim 4, wherein, The voltage constant circuit comprises a transistor Q3, a transistor Q4, a transistor T3, a resistor R2, a resistor R6 and a resistor R7; an emitter of the transistor Q3 is connected with one end of the resistor R1, a base of the transistor Q3 is connected with a base of the transistor Q4, the base of the transistor Q3 is short-circuited with a collector of the transistor Q3, the collector of the transistor Q3 is connected with a collector of the transistor T3, a base of the transistor T3 is connected with one end of the resistor R6, the other end of the resistor R6 is connected at a connecting point of the resistor R5 and the transistor D1, an emitter of the transistor T3 is connected with one end of the resistor R7, the other end of the resistor R7 is connected with a collector of the transistor T6, an emitter of the transistor Q4 is connected with one end of the resistor R1, a collector of the transistor Q4 is connected with one end of the resistor R2, the other end of the resistor R2 is taken as an E port of the LED direct current driving chip U1.

6. The head-mounted LED surgical shadowless lamp circuit of claim 5, wherein, The comparison amplification circuit comprises a transistor T4, a resistor R8, a resistor R10, a resistor R11 and a resistor R12; a collector of the transistor T4 is connected with one end of the resistor R1, an emitter of the transistor T4 is connected with one end of the resistor R8, the other end of the resistor R8 is connected with a collector of the transistor T6, the resistor R11 and the resistor R12 are connected in series, wherein, a non-series end of the resistor R11 is connected with an emitter of the transistor T2, a non-series end of the resistor R12 is grounded; a base of the transistor T4 is connected with one end of the resistor R10, the other end of the resistor R10 is connected at a connecting point of the resistor R11 and the resistor R12.

7. The head-mounted LED surgical shadowless lamp circuit of claim 6, wherein, The current constant circuit comprises a transistor T7, a transistor T8, a resistor R3, a resistor R13, a resistor R14, a resistor R15, a resistor R16 and a resistor R17; a collector of the transistor T7 is connected with one end of the resistor R1, an emitter of the transistor T7 is connected with one end of the resistor R14, the other end of the resistor R14 is connected with one end of the resistor R13, the other end of the resistor R13 is grounded, a base of the transistor T7 is connected at a connecting point of the resistor R11 and the resistor R12; a collector of the transistor T8 is connected with the other end of the resistor R2, an emitter of the transistor T8 is connected with one end of the resistor R15, the other end of the resistor R15 is connected with one end of the resistor R13, the resistor R3 and the resistor R17 are connected in series, wherein, a non-series end of the resistor R3 is connected with a collector of the transistor Q1, a non-series end of the resistor R17 is grounded, a connecting point of the resistor R3 and the resistor R17 is taken as a C port of the LED direct current driving chip U1; a base of the transistor T8 is connected with one end of the resistor R16, the other end of the resistor R16 is connected at the connecting point of the resistor R3 and the resistor R17.

8. The head-mounted LED surgical shadowless lamp circuit of claim 7, wherein, The control output circuit comprises: a transistor T9, a transistor T10 and a resistor R18; a base of the transistor T9 is connected to a common point of the resistor R11 and the resistor R12 in series, a collector of the transistor T9 is connected to one end of the resistor R1, an emitter of the transistor T9 is connected to one end of the resistor R18, a base of the transistor T10 is a D port of the LED direct current driving chip U1, a collector of the transistor T10 is connected to the other end of the resistor R2, an emitter of the transistor T10 is connected to one end of the resistor R18, and the other end of the resistor R18 is grounded.

9. The head-mounted LED surgical shadowless lamp circuit of claim 8, wherein, The soft start circuit comprises: a transistor Q1, a transistor Q2, a resistor R4 and a transistor D4; an emitter of the transistor Q1 and an emitter of the transistor Q2 are connected together and then connected to one end of the resistor R1, a base of the transistor Q1 and a base of the transistor Q2 are connected, the base of the transistor Q2 is short-circuited with a collector of the transistor Q2, the collector of the transistor Q2 is connected to one end of the resistor R4, the other end of the resistor R4 is connected to the other end of the resistor R1, a collector of the transistor D4 is connected to the emitter of the transistor Q2, a base of the transistor D4 is short-circuited with an emitter of the transistor D4, at this time, the transistor D4 is used as a diode, the base of the transistor D4 is connected to a base of the transistor T3, and the base of the transistor D4 is short-circuited with the emitter of the transistor D4 and used as an A port of the LED direct current driving chip U1.

10. A head-mounted LED surgical shadowless lamp, characterized in that The head-mounted LED surgical shadowless lamp circuit is powered by the head-mounted LED surgical shadowless lamp circuit according to any one of claims 1-9.

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