An LED projector power supply circuit

Abstract

The application provides an LED projector power supply circuit, which comprises a first peripheral circuit, a second peripheral circuit, an isolation transformer and a control circuit; the first end of the control circuit is connected with the first end of the first peripheral circuit, the second end of the control circuit is connected with the first end of the second peripheral circuit, the third end of the control circuit is connected with an LED, the second end of the first peripheral circuit and the second end of the second peripheral circuit are connected through the isolation transformer, and the third end of the second peripheral circuit is connected with the LED; and the control circuit is used for outputting constant-voltage power supply and constant-current power supply to the first peripheral circuit and the second peripheral circuit. Compared with the prior art, the application has the advantages of simple topology, low cost and decisive advantages on the miniaturization of equipment, the application utilizes the volt-ampere characteristic of the LED light source and the winding voltage coupling characteristic of the transformer, and only one control chip is needed to realize constant-voltage and constant-current output, the power supply topology structure is simplified, and the production cost is reduced.

Description

Technical Field

[0001] The present invention is applicable to the technical field of LEDs, and in particular relates to a power supply circuit for an LED projector. Background Art

[0002] With the continuous advancement of projection technology, LED light sources are becoming increasingly common in projectors. With advantages such as long light source life, compact size, and no warm-up time, LED projectors have become a key development direction for projection equipment. In LED projectors, the power supply plays a crucial role, driving the LED light source, providing power to the control board, and powering peripheral devices.

[0003] In existing LED projector power supply circuits, such as dual-output LED projector power supplies, built-in LED power supplies often utilize two discrete power supply structures: one independently controlled constant current power supply drives the LED light source, while the other independently controlled constant voltage power supply powers the control board and peripheral devices. Because these multiple outputs require external control circuitry to achieve low standby power consumption, they also suffer from cross-regulation issues, and the constant voltage output has limited accuracy.

[0004] Therefore, a new LED projector power supply circuit is urgently needed to solve the above technical problems. Summary of the Invention

[0005] The present invention proposes a power supply circuit for an LED projector, aiming to simplify the power supply topology and reduce production costs.

[0006] The present invention provides a power supply circuit for an LED projector, comprising a first peripheral circuit, a second peripheral circuit, an isolation transformer, and a control circuit; a first end of the control circuit is connected to a first end of the first peripheral circuit, a second end of the control circuit is connected to a first end of the second peripheral circuit, a third end of the control circuit is connected to an LED, a second end of the first peripheral circuit and a second end of the second peripheral circuit are connected via the isolation transformer, and a third end of the second peripheral circuit is connected to the LED; the control circuit is configured to output a constant voltage power supply and a constant current power supply to the first and second peripheral circuits;

[0007] The control circuit includes an amplifier chip, an output voltage sampling circuit, a voltage loop compensation circuit, a current loop compensation circuit, a current and voltage loop isolation feedback circuit, and a current and voltage regulation circuit;

[0008] The first end of the amplifier chip is connected with the first end of the output voltage sampling circuit, the second end of the output voltage sampling circuit is connected with the first end of the voltage loop compensation circuit, the third end of the output voltage sampling circuit is taken as the third end of the control circuit, the second end of the amplifier chip is grounded, the third end of the amplifier chip is connected with the first end of the current loop compensation circuit, the second end of the voltage loop compensation circuit and the first end of the current-voltage loop isolation feedback circuit respectively, the fourth end of the amplifier chip is grounded, the fifth end of the amplifier chip is connected with the first end of the current-voltage regulation circuit, the sixth end of the amplifier chip is connected with the second end of the current-voltage regulation circuit, the second end of the current loop compensation circuit is connected with the third end of the current-voltage regulation circuit, the fourth end of the current-voltage regulation circuit is taken as the second end of the control circuit, and the second end of the current-voltage loop isolation feedback circuit is taken as the first end of the control circuit.

[0009] Preferably, the current-voltage loop isolation feedback circuit comprises a current-voltage loop isolation feedback chip, a first capacitor, a first resistor and a second resistor, the first end of the first resistor and the first end of the second resistor are connected with each other and connected with a power voltage, the second end of the first resistor is connected with the first end of the current-voltage loop isolation feedback chip, the second end of the current-voltage loop isolation feedback chip is connected with the second end of the second resistor, the second end of the current-voltage loop isolation feedback chip is taken as the first end of the current-voltage loop isolation feedback circuit, the third end of the current-voltage loop isolation feedback chip is grounded, the fourth end of the current-voltage loop isolation feedback chip is taken as the second end of the current-voltage loop isolation feedback circuit, the first end of the first capacitor is connected with the fourth end of the current-voltage loop isolation feedback chip, and the second end of the first capacitor is connected with the third end of the current-voltage loop isolation feedback chip.

[0010] Preferably, the output voltage sampling circuit comprises a third resistor, a fourth resistor and a fifth resistor, the first end of the third resistor is connected with a power voltage, the second end of the third resistor is taken as the second end of the output voltage sampling circuit, the first end of the fourth resistor is taken as the third end of the output voltage sampling circuit, the second end of the fourth resistor is connected with the second end of the third resistor, the second end of the fourth resistor is taken as the first end of the output voltage sampling circuit, the first end of the fifth resistor is connected with the second end of the third resistor, and the second end of the fifth resistor is grounded.

[0011] Preferably, the voltage loop compensation circuit comprises a sixth resistor and a second capacitor, the first end of the sixth resistor is taken as the first end of the voltage loop compensation circuit, the second end of the sixth resistor is connected with the first end of the second capacitor, and the second end of the second capacitor is taken as the second end of the voltage loop compensation circuit.

[0012] Preferably, the current loop compensation circuit includes a third capacitor and a seventh resistor, the first end of the third capacitor serves as the first end of the current loop compensation circuit, the second end of the third capacitor is connected to the first end of the seventh resistor, and the second end of the seventh resistor serves as the second end of the current loop compensation circuit.

[0013] Preferably, the current and voltage regulation circuit includes a fourth capacitor, an eighth resistor, a ninth resistor and a tenth resistor, the first end of the eighth resistor is connected to the power supply voltage, the second end of the eighth resistor is connected to the first end of the fourth capacitor, the first end of the fourth capacitor serves as the second end of the current and voltage regulation circuit, the second end of the fourth capacitor is grounded, the first end of the ninth resistor serves as the first end of the current and voltage regulation circuit, the second end of the ninth resistor serves as the fourth end of the current and voltage regulation circuit, the first end of the tenth resistor serves as the third end of the current and voltage regulation circuit, and the second end of the tenth resistor is connected to the second end of the eighth resistor.

[0014] Preferably, the second peripheral circuit further includes an eleventh resistor, and the eleventh resistor is used to sample the current.

[0015] Preferably, the output turns ratio of the isolation transformer is 6:4.

[0016] Compared to existing technologies, the present invention is suitable for applications with multiple outputs, one of which is a constant current output and the others are constant voltage outputs, where the accuracy of the constant voltage is not critical. The present invention offers a simple topology and low cost, significantly enhancing device miniaturization. By leveraging the volt-ampere characteristics of LED light sources and the voltage coupling characteristics of transformer windings, the present invention requires only one control chip to achieve both constant voltage and constant current outputs, thus reducing production costs by simplifying the power supply topology. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be described in detail below with reference to the accompanying drawings. The above and other aspects of the present invention will become clearer and easier to understand through the detailed description made with reference to the following drawings. In the accompanying drawings:

[0018] Fig. 1 is a schematic structural diagram of a control circuit provided by an embodiment of the present invention;

[0019] Fig. 2 It is a structural diagram of a first peripheral circuit and a second peripheral circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present 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 only used to explain the present invention and are not intended to limit the present invention.

[0021] Please refer to Figs. 1-2 The present invention proposes a power supply circuit for an LED projector, comprising a control circuit 1, a first peripheral circuit 2, a second peripheral circuit 3, and an isolation transformer T1; a first end of the control circuit 1 is connected to a first end of the first peripheral circuit 2, a second end of the control circuit 1 is connected to a first end of the second peripheral circuit 3, a third end of the control circuit 1 is connected to an LED, a second end of the first peripheral circuit 2 and a second end of the second peripheral circuit 3 are connected via the isolation transformer T1, and a third end of the second peripheral circuit 3 is connected to an LED; the control circuit 1 is configured to output a constant voltage power supply and a constant current power supply to the first peripheral circuit 2 and the second peripheral circuit 3;

[0022] The control circuit 1 includes an amplifier chip U2, an output voltage sampling circuit 12, a voltage loop compensation circuit 13, a current loop compensation circuit 14, a current and voltage loop isolation feedback circuit 11, and a current and voltage regulation circuit 15;

[0023] The first end (VCTRL) of the amplifier chip U2 is connected to the first end of the output voltage sampling circuit 12, the second end of the output voltage sampling circuit 12 is connected to the first end of the voltage loop compensation circuit 13, the third end of the output voltage sampling circuit 12 serves as the third end of the control circuit 1, the second end (GND) of the amplifier chip U2 is grounded, the third end (VOUT) of the amplifier chip U2 is respectively connected to the first end of the current loop compensation circuit 14, the second end of the voltage loop compensation circuit 13 and the first end of the current-voltage loop isolation feedback circuit 11, the fourth end (ICTRL) of the amplifier chip U2 is grounded, the fifth end (VSEN) of the amplifier chip U2 is connected to the first end of the current-voltage regulation circuit 15, the sixth end (VCC) of the amplifier chip U2 is connected to the second end of the current-voltage regulation circuit 15, the second end of the current loop compensation circuit 14 is connected to the third end of the current-voltage regulation circuit 15, the fourth end of the current-voltage regulation circuit 15 serves as the second end of the control circuit 1, and the second end of the current-voltage loop isolation feedback circuit 11 serves as the first end of the control circuit 1.

[0024] In an embodiment of the present invention, the current-voltage loop isolation feedback circuit 11 includes a current-voltage loop isolation feedback chip U3, a first capacitor C1, a first resistor R1 and a second resistor R2, the first end of the first resistor R1 and the first end of the second resistor R2 are interconnected and connected to the power supply voltage, the second end of the first resistor R1 is connected to the first end of the current-voltage loop isolation feedback chip U3, the second end of the current-voltage loop isolation feedback chip U3 is connected to the second end of the second resistor R2, the second end of the current-voltage loop isolation feedback chip U3 serves as the first end of the current-voltage loop isolation feedback circuit 11, the third end of the current-voltage loop isolation feedback chip U3 is grounded, the fourth end of the current-voltage loop isolation feedback chip U3 serves as the second end of the current-voltage loop isolation feedback circuit 11, the first end of the first capacitor C1 is connected to the fourth end of the current-voltage loop isolation feedback chip U3, and the second end of the first capacitor C1 is connected to the third end of the current-voltage loop isolation feedback chip U3.

[0025] In an embodiment of the present invention, the output voltage sampling circuit 12 includes a third resistor R3, a fourth resistor R4, and a fifth resistor R5. A first end of the third resistor R3 is connected to a power supply voltage, and a second end of the third resistor R3 serves as the second end of the output voltage sampling circuit 12. A first end of the fourth resistor R4 serves as the third end of the output voltage sampling circuit 12, a second end of the fourth resistor R4 is connected to the second end of the third resistor R3, and a second end of the fourth resistor R4 serves as the first end of the output voltage sampling circuit 12. A first end of the fifth resistor R5 is connected to the second end of the third resistor R3, and a second end of the fifth resistor R5 is grounded.

[0026] In an embodiment of the present invention, the voltage loop compensation circuit 13 includes a sixth resistor R6 and a second capacitor C2, the first end of the sixth resistor R6 serves as the first end of the voltage loop compensation circuit 13, the second end of the sixth resistor R6 is connected to the first end of the second capacitor C2, and the second end of the second capacitor C2 serves as the second end of the voltage loop compensation circuit 13.

[0027] In an embodiment of the present invention, the current loop compensation circuit 14 includes a third capacitor C3 and a seventh resistor R7, the first end of the third capacitor C3 serves as the first end of the current loop compensation circuit 14, the second end of the third capacitor C3 is connected to the first end of the seventh resistor R7, and the second end of the seventh resistor R7 serves as the second end of the current loop compensation circuit 14.

[0028] In an embodiment of the present invention, the current-voltage regulation circuit 15 includes a fourth capacitor C4, an eighth resistor R8, a ninth resistor R9, and a tenth resistor R10. The first end of the eighth resistor R8 is connected to a power supply voltage, the second end of the eighth resistor R8 is connected to the first end of the fourth capacitor C4, the first end of the fourth capacitor C4 serves as the second end of the current-voltage regulation circuit 15, the second end of the fourth capacitor C4 is grounded, the first end of the ninth resistor R9 serves as the first end of the current-voltage regulation circuit 15, the second end of the ninth resistor R9 serves as the fourth end of the current-voltage regulation circuit 15, the first end of the tenth resistor R10 serves as the third end of the current-voltage regulation circuit 15, and the second end of the tenth resistor R10 is connected to the second end of the eighth resistor R8. The ninth resistor R9 is used to sample the LED current.

[0029] In the embodiment of the present invention, the second peripheral circuit 3 further includes an eleventh resistor R11 , and the eleventh resistor R11 is used to sample the current.

[0030] In the embodiment of the present invention, the output turns ratio of the isolation transformer T1 is 6:4.

[0031] Specifically, a projector generally has two states, namely, the power-on standby state and the power-on projection working state; when the projector is connected to the power supply, the projector is in the standby working state, at which time the LED is not working, the amplifier chip U2 is working in the constant voltage loop state, and the current loop is open, and the two outputs are stable; when the projector is turned on, the LED light source is lit, and at this time the amplifier chip U2 is working in the constant current loop, and the voltage loop is open. The LED volt-ampere characteristics show that the LED works under a constant current, so the LED voltage can be regarded as fixed (without considering the device error and temperature characteristics). At this time, the LED output is equivalent to a fixed voltage. Combined with the transformer winding voltage coupling characteristics (the winding voltage is proportional to the number of winding turns), if you want to get another stable voltage, you only need to adjust the transformer winding ratio in proportion; with Fig. 2 For example, the built-in power supply has two outputs: a constant current of 2.8A for the LED driver and a constant voltage of 12V for the control board. The measured LED voltage at 2.8A is 17.5V. The transformer output turns ratio is designed to be 17.5 / 12, approximately equal to 6 / 4. The actual design includes 6 turns for the LED winding and 4 turns for the 12V winding.

[0032] Compared to existing technologies, the present invention is suitable for applications with multiple outputs, one of which is a constant current output and the others are constant voltage outputs, where the accuracy of the constant voltage is not critical. The present invention offers a simple topology and low cost, significantly enhancing device miniaturization. By leveraging the volt-ampere characteristics of LED light sources and the voltage coupling characteristics of transformer windings, the present invention requires only one control chip to achieve both constant voltage and constant current outputs, thus reducing production costs by simplifying the power supply topology.

[0033] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0034] The embodiments of the present invention are described above in conjunction with the accompanying drawings. What is disclosed is only a preferred embodiment of the present invention. However, the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms and equivalent changes without departing from the scope of protection of the purpose of the present invention and the claims, which are all within the protection of the present invention.

Claims

1. A power supply circuit for an LED projector, characterized in that: The device comprises a first peripheral circuit, a second peripheral circuit, an isolation transformer, and a control circuit; a first end of the control circuit is connected to a first end of the first peripheral circuit, a second end of the control circuit is connected to a first end of the second peripheral circuit, a third end of the control circuit is connected to an LED, a second end of the first peripheral circuit and a second end of the second peripheral circuit are connected via the isolation transformer, and a third end of the second peripheral circuit is connected to an LED; the control circuit is configured to output a constant voltage power supply and a constant current power supply to the first peripheral circuit and the second peripheral circuit; The control circuit includes an amplifier chip, an output voltage sampling circuit, a voltage loop compensation circuit, a current loop compensation circuit, a current and voltage loop isolation feedback circuit, and a current and voltage regulation circuit; The first end VCTRL of the amplifier chip is connected to the first end of the output voltage sampling circuit, the second end of the output voltage sampling circuit is connected to the first end of the voltage loop compensation circuit, the third end of the output voltage sampling circuit serves as the third end of the control circuit, the second end GND of the amplifier chip is grounded, the third end VOUT of the amplifier chip is respectively connected to the first end of the current loop compensation circuit, the second end of the voltage loop compensation circuit and the first end of the current-voltage loop isolation feedback circuit, the fourth end ICTRL of the amplifier chip is grounded, the fifth end VSEN of the amplifier chip is connected to the first end of the current-voltage regulation circuit, the sixth end VCC of the amplifier chip is connected to the second end of the current-voltage regulation circuit, the second end of the current loop compensation circuit is connected to the third end of the current-voltage regulation circuit, the fourth end of the current-voltage regulation circuit serves as the second end of the control circuit, and the second end of the current-voltage loop isolation feedback circuit serves as the first end of the control circuit.

2. The LED projector power supply circuit according to claim 1, wherein: The current-voltage loop isolation feedback circuit includes a current-voltage loop isolation feedback chip, a first capacitor, a first resistor and a second resistor. The first end of the first resistor and the first end of the second resistor are connected to each other and to the power supply voltage. The second end of the first resistor is connected to the first input end of the current-voltage loop isolation feedback chip, and the second input end of the current-voltage loop isolation feedback chip is connected to the second end of the second resistor. The second input end of the current-voltage loop isolation feedback chip serves as the first end of the current-voltage loop isolation feedback circuit. The third output end of the current-voltage loop isolation feedback chip is grounded. The fourth output end of the current-voltage loop isolation feedback chip serves as the second end of the current-voltage loop isolation feedback circuit. The first end of the first capacitor is connected to the fourth output end of the current-voltage loop isolation feedback chip, and the second end of the first capacitor is connected to the third output end of the current-voltage loop isolation feedback chip.

3. The LED projector power supply circuit according to claim 1, wherein: The output voltage sampling circuit includes a third resistor, a fourth resistor, and a fifth resistor. The first end of the third resistor is connected to the power supply voltage, the second end of the third resistor serves as the second end of the output voltage sampling circuit, the first end of the fourth resistor serves as the third end of the output voltage sampling circuit, the second end of the fourth resistor is connected to the second end of the third resistor, the second end of the fourth resistor serves as the first end of the output voltage sampling circuit, the first end of the fifth resistor is connected to the second end of the third resistor, and the second end of the fifth resistor is grounded.

4. The LED projector power supply circuit according to claim 1, wherein: The voltage loop compensation circuit includes a sixth resistor and a second capacitor, the first end of the sixth resistor serves as the first end of the voltage loop compensation circuit, the second end of the sixth resistor is connected to the first end of the second capacitor, and the second end of the second capacitor serves as the second end of the voltage loop compensation circuit.

5. The LED projector power supply circuit according to claim 1, wherein: The current loop compensation circuit includes a third capacitor and a seventh resistor, the first end of the third capacitor serves as the first end of the current loop compensation circuit, the second end of the third capacitor is connected to the first end of the seventh resistor, and the second end of the seventh resistor serves as the second end of the current loop compensation circuit.

6. The LED projector power supply circuit according to claim 1, wherein: The current and voltage regulation circuit includes a fourth capacitor, an eighth resistor, a ninth resistor and a tenth resistor. The first end of the eighth resistor is connected to the power supply voltage, the second end of the eighth resistor is connected to the first end of the fourth capacitor, the first end of the fourth capacitor serves as the second end of the current and voltage regulation circuit, the second end of the fourth capacitor is grounded, the first end of the ninth resistor serves as the first end of the current and voltage regulation circuit, the second end of the ninth resistor serves as the fourth end of the current and voltage regulation circuit, the first end of the tenth resistor serves as the third end of the current and voltage regulation circuit, and the second end of the tenth resistor is connected to the second end of the eighth resistor.

7. The LED projector power supply circuit according to claim 1, wherein: The second peripheral circuit further includes an eleventh resistor, and the eleventh resistor is used to sample current.

8. The LED projector power supply circuit according to claim 1, wherein: The output turns ratio of the isolation transformer is 6:4.

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