CN111642038A

CN111642038A - LED drive circuit and projector

Info

Publication number: CN111642038A
Application number: CN202010502230.3A
Authority: CN
Inventors: 高文刚
Original assignee: Goertek Optical Technology Co Ltd
Current assignee: Goertek Optical Technology Co Ltd
Priority date: 2020-06-04
Filing date: 2020-06-04
Publication date: 2020-09-08
Anticipated expiration: 2040-06-04
Also published as: CN111642038B

Abstract

The invention discloses an LED drive circuit and a projector, wherein the projector comprises a red, green and blue LED lamp, and the LED drive circuit comprises: an LED driver configured to output an LED driving signal; the controlled end of the current expansion circuit is connected with the LED driver, and the output end of the current expansion circuit is connected with one electrode of at least one LED lamp in the red, green and blue LED lamps; the controlled end of the switch control circuit is connected with the LED driver, and the output end of the switch control circuit is connected with the other electrode of at least one LED lamp in the red, green and blue LED lamps; the current expansion circuit and the switch control circuit work when receiving the LED driving signal to light the LED lamp. The invention can improve the LED driving current under the original driving framework without changing the program and the output of the LED driver.

Description

LED drive circuit and projector

Technical Field

The invention relates to the technical field of LED driving, in particular to an LED driving circuit and a projector.

Background

The LED is applied to various devices, for example, in a projector, in actual use, as the brightness requirement of the LED is continuously increased, the driving current is continuously increased, and the driving range of the LED driving chip provided by TI is limited, which cannot meet the requirement of increasing the LED driving current again under the existing driving current of the DLP projector, if the driving current is to be increased, the program of the DLP driver and the peripheral circuit thereof need to be changed, so that the existing TI DLP driving system cannot be used.

Disclosure of Invention

The invention mainly aims to provide an LED driving circuit and a projector, and aims to improve the current driving capability of an LED.

In order to achieve the above object, the present invention provides an LED driving circuit, which is applied to a projector, wherein the projector includes a red, green and blue LED lamp, and the LED driving circuit includes:

an LED driver configured to output an LED driving signal;

the controlled end of the current expansion circuit is connected with the LED driver, and the output end of the current expansion circuit is connected with one electrode of at least one LED lamp in the red, green and blue LED lamps;

the controlled end of the switch control circuit is connected with the LED driver, and the output end of the switch control circuit is connected with the other electrode of at least one LED lamp in the red, green and blue LED lamps; the current expansion circuit and the switch control circuit work when receiving the LED driving signal to light the LED lamp.

Optionally, the number of the output ends of the current amplifying circuit is two, and the two output ends of the current amplifying circuit are respectively connected with the blue LED lamp and the green LED lamp in the red, green and blue three-color LED lamp in a one-to-one correspondence manner;

the switch control circuit comprises a first electronic switch and a second electronic switch, and the first electronic switch and the second electronic switch are respectively connected with blue LED lamps and green LED lamps in red, green and blue LED lamps in a one-to-one correspondence mode.

Optionally, the LED driver includes a first LED driving signal output end and a second LED driving signal output end, and the first LED driving signal output end of the LED driver is connected to the current expanding circuit and the switch control circuit, respectively;

and a second LED driving signal output end of the LED driver and a red LED lamp in the red, green and blue LED lamps.

Optionally, the LED driving circuit further includes a first diode and a second diode, and anodes of the first diode and the second diode are respectively connected to the controlled end of the current spreading circuit; and the cathodes of the first diode and the second diode are connected with a first driving signal output end of the LED driver.

Optionally, the projector further includes a Bp LED lamp, and one of the two output ends of the current spreading circuit is further connected to an electrode of the Bp LED lamp; one of the two output ends of the switch control circuit is also connected with the other end of the Bp LED lamp.

Optionally, the current spreading circuit includes a first current spreading branch and a second current spreading branch;

the two output ends of the first current expansion branch are respectively connected with blue LED lamps and green LED lamps in red, green and blue LED lamps in a one-to-one correspondence manner;

the switch control circuit comprises a first switch control branch and a second switch control branch; the first switch control branch comprises a first electronic switch and a second electronic switch, and the first electronic switch and the second electronic switch are respectively connected with blue LED lamps and green LED lamps in red, green and blue LED lamps in a one-to-one correspondence manner;

the output end of the second current expanding branch circuit is connected with one electrode of a red LED lamp in the red, green and blue LED lamps, and the output end of the second switch control branch circuit is connected with the other electrode of the red LED lamp in the red, green and blue LED lamps.

Optionally, the projector further includes a Bp LED lamp, and one of the two output ends of the first current spreading branch is further connected to an electrode of the Bp LED lamp; one of the two output ends of the first switch control branch is also connected with the other end of the Bp LED lamp.

Optionally, the LED driving circuit further includes a third diode, a fourth diode, and a fifth diode, and anodes of the third diode and the fourth diode are respectively connected to the controlled end of the first current spreading branch; cathodes of the third diode and the fourth diode are connected with a first driving signal output end of the LED driver;

and the anode of the fifth diode is connected with the controlled end of the second current spreading branch, and the cathode of the fifth diode is connected with the second driving signal output end of the LED driver.

Optionally, the LED driving circuit further includes an LED controller, and an output end of the LED controller is connected to the LED driver; the LED controller is configured to output a corresponding LED control signal to the LED driver according to the received image data.

The invention also provides a projector which comprises the LED driving circuit.

The LED driving circuit is configured to output an LED driving signal through an LED lamp LED driver; and the current expansion circuit and the switch control circuit are respectively connected with two electrodes of the LED lamp and are controlled based on LED drive, and the current expansion circuit and the switch control circuit work when receiving an LED drive signal to light the LED lamp. The invention can improve the LED driving current without changing the program and the output of the LED driver under the original driving framework, and the current value can be set at will. Meanwhile, the circuit can ensure the synchronism of the LED switch, and the operation stability of the system is ensured.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

FIG. 1 is a functional block diagram of an LED driving circuit according to an embodiment of the present invention;

fig. 2 is a schematic circuit diagram of an LED driving circuit according to an embodiment of the invention;

FIG. 3 is a schematic circuit diagram of an LED driving circuit according to another embodiment of the present invention;

fig. 4 is a schematic circuit diagram of an LED driving circuit according to another embodiment of the present invention.

The reference numbers illustrate:

the implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that, if directional indications (such as up, down, left, right, front, and back … …) are involved in the embodiment of the present invention, the directional indications are only used to explain the relative positional relationship between the components, the movement situation, and the like in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indications are changed accordingly.

In addition, if there is a description of "first", "second", etc. in an embodiment of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.

The invention provides an LED driving circuit which is suitable for various LED light source devices.

Among them, the LED Light source device may be a projector, such as a DLP (Digital Light Processing), which is a device composed of a high-speed Digital Light reflecting switch array based on semiconductor manufacturing technology. The DMD can precisely control the gray scale of light by adopting a binary pulse width modulation technology, and a DLP system is formed by image processing, a memory, a light source and an optical system, so that a large-screen, high-brightness, seamless and high-contrast color image can be projected. The image signal is usually processed digitally and then the light is projected. The optical engine is one of the most important components in DLP projection systems. The following embodiments are described by taking an example of an LED driving circuit applied to a projector, and the LED driving circuit of the present invention is specifically applied to driving red, green and blue LEDs of a projector. DLP projection systems are generally composed of four parts, a light emitting part, a DMD, an optical element, and a structural part. The quality of the light source system directly affects the projection quality of the picture, and with the development of semiconductor technology, the LED becomes an important light source. With the continuous update of projection technology, the micro projector of the DLP projection mode proposed by TI, the DLP projector is increasingly popular with users as a product of TI companies. The volume, brightness, resolution and contrast are all better than those of the early white light LED LCOS technology projector, and the driving scheme is the simplest and the high efficiency only by adopting a TI driving chip set. However, in actual use, the driving current is continuously increased due to the continuously increased brightness requirement of the LED, and the driving range of the LED driving chip provided by the TI is limited, so that the requirement of increasing the driving current of the LED again under the existing driving current of the DLP projector cannot be met.

Referring to fig. 1 to 4, in an embodiment of the present invention, the LED driving circuit includes:

an LED driver 10 configured to output an LED driving signal;

the controlled end of the current expanding circuit 20 is connected with the LED driver 10, and the output end of the current expanding circuit 20 is connected with an electrode of at least one LED lamp of the red, green and blue LED lamps;

the controlled end of the switch control circuit 30 is connected with the LED driver 10, and the output end of the switch control circuit 30 is connected with the other electrode of at least one LED lamp in the red, green and blue LED lamps; wherein the current spreading circuit 20 and the switch control circuit 30 operate to light the LED lamp when receiving the LED driving signal.

In this embodiment, the LED driving circuit further includes an LED controller 40, and an output end of the LED controller 40 is connected to the LED driver 10; the LED controller 40 is configured to output a corresponding LED control signal to the LED driver 10 according to the received image data.

The LED controller 40 can be implemented by a Digital Light Processor (DLP), a video decoder is further disposed in the LED driving circuit, an input end of the video decoder is connected to a synthesized video signal output end of the terminal, an output end of the video decoder is connected to an input end of the DLP controller, an output end of the DLP controller is connected to the LED driver 10, the video decoder is configured to decode and convert the synthesized video signal from the terminal into a full Digital signal including image information, and the DLP controller is configured to coordinate with a Digital video image signal, an LED Light source and a projection lens to process the full Digital signal into a signal recognizable to the Digital micromirror assembly, and output the signal to the Digital micromirror assembly to project the image information on a large screen or other surfaces. The LED controller 40 and the terminal can be connected through a cable, and can also be connected in a wireless mode such as Bluetooth, WIFI, infrared and the like.

The LED driver 10 may be implemented by using a DLPA3000, and the LED driver 10 may output a constant current and constant duty ratio LED driving signal under the control of the DLP controller. Meanwhile, under the control of a DLP controller synchronous signal, Red, Green and Blue LED lamps in the projector are respectively controlled, namely Red, Green and Blue LEDs are lighted in turn, so that an image is projected. Green _ Switch & Blue _ Switch are control signals for lighting the LED externally output by the DLPA3000, and the Green & Blue LED lighting control signals are respectively controlled in the circuit.

It is understood that the current expanding circuit 20 and the switch control circuit 30 are both used for amplifying the current for driving the LED lamp to operate, so as to increase the driving current of the LED lamp. The switch control circuit 30 may be implemented by a switch control circuit 30 composed of power transistors such as MOS transistors. The MOS transistor may be turned on when receiving a high level (or a low level) and turned off when receiving a low level (or a high level). The current amplifying circuit 20 can be realized by adopting a TPS92641 type power supply driver, the LED driving current adjustment of 0 to 20A can be realized by setting the driving current of the power supply driver, the driving signal output end of the LED driver 10 is connected to the enable end of the power supply driver, and operates when receiving a high level (or a low level) and stands by when receiving a low level (or a high level). In the present embodiment, taking the low level active as an example, the switch control circuit 30 and the current spreading circuit 20 receive the synchronization signal output by the LED driver 10, and are controlled by the LED driver 10 to operate or wait. The current spreading circuit 20 may be connected to the anode of the LED lamp and the switch control circuit 30 may be connected to the cathode of the LED lamp. Of course, in other embodiments, the connection relationship between the current spreading circuit 20 and the switch control circuit 30 and the LED lamp may be modified and adjusted, and is not limited herein.

Specifically, when receiving a low-level LED driving signal output from the LED driver 10, the current spreading circuit 20 and the switch control circuit 30 operate simultaneously, and the LED lamp is turned on, and when receiving a high-level LED driving signal output from the LED driver 10, the current spreading circuit 20 and the switch control circuit 30 stand by simultaneously, and the LED lamp is turned off.

The driving current of the red LED lamp LD1 is different from the driving currents of the blue LED lamp LD2 and the green LED lamp LD3 according to the characteristics of the red, green and blue LED lamps themselves, and the driving current of the red LED lamp LD1 is generally smaller than the driving currents of the blue LED lamp LD2 and the green LED lamp LD 3. Therefore, according to the application requirements of the product, for example, in the product with higher brightness requirement, in the application where the brightness of the red, green and blue three-color LED lamps needs to be improved, the current expanding circuit 20 and the switch control circuit 30 simultaneously control the three-color LED lamps to operate. In the application of red, green and blue LEDs, which only needs to increase the brightness of the blue LED LD2 or the green LED LD3, the current expanding circuit 20 and the switch control circuit 30 simultaneously control the blue LED LD2 or the green LED LD3 to work.

The LED driving circuit of the present invention is configured to output an LED driving signal through an LED lamp LED driver 10; and the current expanding circuit 20 and the switch control circuit 30 are respectively connected with two electrodes of the LED lamp, the current expanding circuit 20 and the switch control circuit 30 are controlled based on LED driving, and the current expanding circuit 20 and the switch control circuit 30 work when receiving an LED driving signal to light the LED lamp. According to the invention, the LED driving current can be improved under the original driving framework without changing the program and the output of the LED driver 10, and the current value can be set at will. Meanwhile, the circuit can ensure the synchronism of the LED switch, and the operation stability of the system is ensured.

Referring to fig. 1 to 2, in an embodiment, two output ends of the current spreading circuit 20 are provided, and the two output ends of the current spreading circuit 20 are respectively connected to the blue LED lamps LD2 and the green LED lamps LD3 of the red, green and blue three-color LED lamps in a one-to-one correspondence;

the switch control circuit 30 comprises a first electronic switch K1 and a second electronic switch K2, wherein the first electronic switch K1 and the second electronic switch K2 are respectively connected with blue LED lamps LD2 and green LED lamps LD3 in red, green and blue three-color LED lamps in a one-to-one correspondence mode.

In an embodiment, the LED driver 10 includes a first LED driving signal output terminal and a second LED driving signal output terminal, and the first LED driving signal output terminal of the LED driver 10 is respectively connected to the current spreading circuit 20 and the switch control circuit 30;

and a second LED driving signal output end of the LED driver 10 is connected to a red LED lamp LD1 in the red, green and blue LED lamps.

In this embodiment, the current spreading circuit 20 and the switch control circuit 30 are used to control the blue LED lamp LD2 and the green LED lamp LD3 in the red, green and blue LED lamps, that is, to increase the driving currents of the blue LED lamp LD2 and the green LED lamp LD 3. The red LED lamp LD1 in the red, green and blue three-color LED lamp is directly driven by the LED driver 10, the LED driver 10 is integrated with a DC-DC module and a switch control circuit 30, the DC-DC module is used for providing working voltage for the red LED lamp LD1, the output end of the DC-DC module is connected with the anode of the red LED lamp LD1, the switch control circuit 30 is connected with the cathode of the red LED lamp LD1, and when the switch control circuit 30 is closed, the LED lamp is lighted.

And outputting a constant-current constant-duty-ratio LED driving signal to the LED driver 10 under the control of the DLP controller. Therefore, the DLP driver outputs synchronous LED driving signals, and respectively controls Red, Green and Blue LEDs to be lighted in turn, so that images are projected. Green _ Switch & Blue _ Switch is a control signal for lighting the LED externally output by the DLPA3000, and the Green and/or Blue LED lighting control signals are controlled in the circuit respectively. The LED driver 10 outputs an active low-level LED driving signal, and when receiving the low-level LED driving signal output by the LED driver 10, the current spreading circuit 20 and the switch control circuit 30 operate simultaneously to turn on the blue LED lamp LD2 and/or the green LED lamp LD3, and when receiving the high-level LED driving signal output by the LED driver 10, the current spreading circuit 20 and the switch control circuit 30 stand by simultaneously, and both the blue LED lamp LD2 and the green LED lamp LD3 are turned off. In this process, the red LED lamp LD1 is directly driven by the LED driver 10, so that when the red, green, and blue LEDs are lit, different color outputs are realized to complete image display. It can be understood that when the DLP driver is adopted for implementation, two resistors R1 and R2 are further arranged in parallel on the periphery of the DLP driver, R1 and R2 are dummy loads, the dummy loads R1 and R2 are provided, the DLPA3000 cannot automatically protect a shutdown system due to the fact that Green and Blue LEDs are driven by the TPS92641, and an optical mechanical system can be effectively protected. In addition, the two resistors R1, R2 may also be used for current limiting to reduce the power consumption of the LED driver 10 itself.

The LED driving circuit further comprises a first current sampling resistor R4, and the first current sampling resistor R4 is arranged between the red LED lamp LD1 and the ground in series.

VCC is LED driving voltage, IRed is working current when the red LED lamp LD1 is normally lighted; VLED is the operating voltage across the LED, and ILED _ Min is the minimum LED drive current allowed for DLPA3000 operation. In the above embodiment, the LED driving circuit may be applied to an LED light source device with a red LED driving current of 6A or less and blue and green LEDs driving currents of > 6A. Wherein, R4 is the resistance of the first current sampling resistor R4.

Referring to fig. 1 to 3, in an embodiment, the LED driving circuit further includes a first diode D1 and a second diode D2, and anodes of the first diode D1 and the second diode D2 are respectively connected to the controlled terminal of the current spreading circuit 20; cathodes of the first diode D1 and the second diode D2 are connected to a first driving signal output terminal of the LED driver 10.

In this embodiment, the first diode D1 and the second diode D2 form an or logic gate circuit, so as to ensure that the current expanding circuit 20 can be triggered to operate when the LED driver 10 outputs any one of the blue LED driving signal and the green LED driving signal. At this time, when receiving the LED driving signal (blue LED driving signal and/or green LED driving signal) output from the LED driver 10, the switching control circuit 30 controls the cathode of the LED lamp of the corresponding color to be grounded, so that the LED lamp of the corresponding color is turned on by the current expanding circuit 20 and the switching control circuit 30. That is, the current spreading circuit 20 and the Switch control circuit 30 receive the synchronous signal Green _ Switch & Blue _ Switch output by the DLPA3000 to control the Switch of the current spreading circuit 20 and the Switch of the Switch K1& K2 formed by the MOS transistor, thereby ensuring that the Green & Blue LEDs are turned on in turn. The LED driving circuit further comprises a second current sampling resistor R6, and the second current sampling resistor R6 is arranged between the blue LED lamp LD2 and the green LED lamp LD3 in the red, green and blue three-color LED lamp in series and the ground. Iadj sets the reference voltage input for the current.

Wherein IG and IB are TPS92641 output currents; vref sets the reference voltage for the Iadj pin input current of TPS 92641. R6 is the resistance value of the second current sampling resistor.

Referring to fig. 1 to 3, in an embodiment, the projector further includes a Bp LED lamp LD4, and one of two output terminals of the current spreading circuit 20 is further connected to one electrode of the Bp LED lamp LD 4; one of the two output terminals of the switch control circuit 30 is also connected to the other of the Bp LED lamp LD 4.

It can be understood that, in order to increase the brightness of the green LED lamp LD3, a Bp LED lamp LD4 is further connected in series in the loop of the green LED lamp LD3, and the Bp LED lamp LD4 is turned on together with the green LED lamp LD3, that is, when the LED driver 10 outputs a green LED driving signal, the current expanding circuit 20 is triggered to operate. At this time, upon receiving the green LED driving signal outputted from the LED driver 10, the switch control circuit 30 controls the cathodes of the corresponding green LED lamps LD3 and Bp LED lamp LD4 to be grounded, so that the Bp LED lamp LD4 and the green LED lamp LD3 are lit under the action of the current spreading circuit 20 and the switch control circuit 30.

Referring to fig. 1 to 4, in an embodiment, the current spreading circuit 20 includes a first current spreading branch 21 and a second current spreading branch 22;

the two output ends of the first current spreading branch 21 are respectively connected with the blue LED lamps LD2 and the green LED lamps LD3 of the red, green and blue three-color LED lamps in a one-to-one correspondence manner;

the switch control circuit 30 comprises a first switch control branch 31 and a second switch control branch 32; the first switch control branch 31 comprises a first electronic switch K1 and a second electronic switch K2, and the first electronic switch K1 and the second electronic switch K2 are respectively connected with blue LED lamps LD2 and green LED lamps LD3 in red, green and blue three-color LED lamps in a one-to-one correspondence manner;

the output end of the second current expanding branch 22 is connected to one electrode of the red LED lamp LD1 in the red, green and blue three-color LED lamp, and the output end of the second switch control branch 32 is connected to the other electrode of the red LED lamp LD1 in the red, green and blue three-color LED lamp.

In this embodiment, the current spreading circuit 20 and the switch control circuit 30 are both two paths, and one path is used to control the blue LED lamp LD2 and the green LED lamp LD3 in the red, green and blue three-color LED lamp, i.e., to increase the driving currents of the blue LED lamp LD2 and the green LED lamp LD 3. The other path controls a red LED lamp LD1 in the red, green and blue LED lamps.

And outputting a constant-current constant-duty-ratio LED driving signal to the LED driver 10 under the control of the DLP controller. Therefore, the DLP driver outputs synchronous LED driving signals, and respectively controls Red, Green and Blue LEDs to be lighted in turn, so that images are projected. Green _ Switch & Blue _ Switch is a control signal for lighting the LED externally output by the DLPA3000, and the Green and/or Blue LED lighting control signals are controlled in the circuit respectively. The LED driver 10 outputs a low-level effective LED driving signal, when receiving the low-level LED driving signal output by the LED driver 10, the first current spreading branch 21 and the first switch control branch 31 operate simultaneously, and the blue LED lamp LD2 and/or the green LED lamp LD3 are turned on, and when receiving the high-level LED driving signal output by the LED driver 10, the current spreading circuit 20 and the switch control circuit 30 are in standby simultaneously, and the blue LED lamp LD2 and the green LED lamp LD3 are both turned off. Similarly, when receiving the low-level LED driving signal output by the LED driver 10, the second current expanding branch 22 and the second switch control branch 32 operate simultaneously, and the red LED lamp LD1 is turned on, and when receiving the high-level LED driving signal output by the LED driver 10, the second current expanding branch 22 and the second switch control branch 32 are in standby state simultaneously, and the red LED lamp LD1 is turned off. Therefore, when the red, green and blue LED lamps are respectively lightened, the output of different colors is realized, and the image display is completed. It can be understood that when the DLP driver is adopted for implementation, three resistors R1, R2 and R3 are further arranged in parallel on the periphery of the DLP driver, R1& R2& R3 are dummy loads, the dummy loads R1& R2& R3 are provided, the DLPA3000 cannot automatically protect a closing system because Red & Green & Blue LEDs are driven by the TPS92641, and an optical mechanical system can be effectively protected. In addition, the three resistors R1, R2, R3 may also be used for current limiting to reduce the power consumption of the LED driver 10 itself.

Referring to fig. 1 to 4, in an embodiment, the projector further includes a Bp LED lamp LD4, and one of two output ends of the first current spreading branch 21 is further connected to an electrode of the Bp LED lamp LD 4; one of the two output terminals of the first switch control branch 31 is further connected to the other of the Bp LED lamps LD 4.

It can be understood that, in order to increase the brightness of the green LED lamp LD3, a Bp LED lamp LD4 is further disposed in series in the loop of the green LED lamp LD3, and the Bp LED lamp LD4 is lit along with the green LED lamp LD3, that is, when the LED driver 10 outputs a green LED driving signal, the first current spreading branch 21 is triggered to operate. At this time, upon receiving the green LED driving signal outputted from the LED driver 10, the first switch control branch 31 controls the cathodes of the corresponding green LED lamps LD3 and Bp LED lamp LD4 to be grounded, so that the Bp LED lamp LD4 and the green LED lamp LD3 are turned on under the action of the current spreading circuit 20 and the switch control circuit 30.

Referring to fig. 1 to 4, in an embodiment, the LED driving circuit further includes a third diode D3, a fourth diode D4, and a fifth diode D5, anodes of the third diode D3 and the fourth diode D4 are respectively connected to the controlled end of the first current spreading branch 21; cathodes of the third diode D3 and the fourth diode D4 are connected with a first driving signal output terminal of the LED driver 10;

an anode of the fifth diode D5 is connected to the controlled terminal of the second current spreading branch 22, and a cathode of the fifth diode D5 is connected to the second driving signal output terminal of the LED driver 10.

In this embodiment, the third diode D3 and the fourth diode D4 form an or logic gate circuit, so as to ensure that the current expanding circuit 20 can be triggered to operate when the LED driver 10 outputs any one of the blue LED driving signal and the green LED driving signal. At this time, when receiving the LED driving signal (blue LED driving signal and/or green LED driving signal) output by the LED driver 10, the first switch control branch 31 controls the cathode of the LED lamp of the corresponding color to be grounded, so that the LED lamp of the corresponding color is turned on under the action of the first current spreading branch 21 and the first switch control branch 31. That is, the first current spreading branch 21 and the first Switch control branch 31 receive the synchronization signal Green _ Switch & Blue _ Switch output by the DLPA3000 to control the Switch of the current spreading circuit 20 and the Switch K4& K5 formed by the MOS transistor, thereby ensuring that the Green & Blue LEDs are turned on in turn. The fifth diode D5 is a unidirectional conducting element, and is configured to increase the sensitivity of the second current spreading branch 22 to the red LED driving signal, so as to ensure that the red LED lamp LD1 can be smoothly conducted.

The LED driving circuit further comprises a third current sampling resistor R7 and a fourth current sampling resistor R8, and the third current sampling resistor R7 is arranged between a blue LED lamp LD2 and a green LED lamp LD3 in the red, green and blue three-color LED lamp and the ground in series. The fourth current sampling resistor R8 is serially connected between the red LED lamp LD1 of the red, green and blue LED lamps and ground Iadj as a current setting reference voltage input terminal.

Wherein, IR, IG and IB are TPS92641 output currents; vref sets the reference voltage for the Iadj pin input current of TPS 92641. R7 is the resistance value of the third sampling resistor, and R8 is the resistance value of the fourth sampling resistor. In the above embodiment, the LED driving circuit may be applied to an LED light source device in which the driving current of the red LED is > 6A and the driving currents of the blue LED and the green LED are > 6A. The LED driving circuit can be applied to DLP projection systems and laser projection systems, in particular to projection systems with high-brightness LEDs as light sources. The LED drive circuit can conveniently improve the LED drive current on the basis of the original TI scheme, and the current value can be set at will. Meanwhile, the circuit can ensure the synchronism of the LED switch, and the operation stability of the system is ensured. The original framework is not required to be changed, the development time and difficulty of the circuit can be effectively reduced, and the LED driving circuit is favorable for popularization and application in high-current products.

The invention also provides a projector which comprises the LED driving circuit. The detailed structure of the LED driving circuit can refer to the above embodiments, and is not described herein; it can be understood that, because the LED driving circuit is used in the projector of the present invention, the embodiment of the projector of the present invention includes all technical solutions of all embodiments of the LED driving circuit, and the achieved technical effects are also completely the same, and are not described herein again.

The above description is only an alternative embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. An LED drive circuit is applied to a projector, the projector comprises a red, green and blue LED lamp, and the LED drive circuit is characterized by comprising:

an LED driver configured to output an LED driving signal;

2. The LED driving circuit according to claim 1, wherein the current spreading circuit has two output terminals, and the two output terminals of the current spreading circuit are respectively connected to the blue LED lamps and the green LED lamps of the three-color red, green and blue LED lamps in a one-to-one correspondence manner;

3. The LED driver circuit of claim 2, wherein the LED driver includes a first LED driving signal output and a second LED driving signal output, the first LED driving signal output of the LED driver being connected to the current spreading circuit and the switch control circuit, respectively;

4. The LED driving circuit according to claim 3, further comprising a first diode and a second diode, anodes of the first diode and the second diode being respectively connected to the controlled terminal of the current spreading circuit; and the cathodes of the first diode and the second diode are connected with a first driving signal output end of the LED driver.

5. The LED driving circuit according to claim 2, wherein the projector further comprises a Bp LED lamp, one of the two output terminals of the current spreading circuit is further connected to an electrode of the Bp LED lamp; one of the two output ends of the switch control circuit is also connected with the other end of the Bp LED lamp.

6. The LED driving circuit of claim 1, wherein the current spreading circuit comprises a first current spreading branch and a second current spreading branch;

7. The LED driving circuit according to claim 6, wherein the projector further comprises a Bp LED lamp, one of the two output terminals of the first current spreading branch is further connected to an electrode of the Bp LED lamp; one of the two output ends of the first switch control branch is also connected with the other end of the Bp LED lamp.

8. The LED driving circuit according to claim 6, further comprising a third diode, a fourth diode and a fifth diode, wherein anodes of the third diode and the fourth diode are respectively connected to the controlled end of the first current spreading branch; cathodes of the third diode and the fourth diode are connected with a first driving signal output end of the LED driver;

9. The LED driving circuit according to any one of claims 1 to 8, further comprising an LED controller, wherein an output terminal of the LED controller is connected to the LED driver; the LED controller is configured to output a corresponding LED control signal to the LED driver according to the received image data.

10. A projector characterized by comprising the LED driving circuit according to any one of claims 1 to 9.