CN216849225U

CN216849225U - LED backlight driving power supply device

Info

Publication number: CN216849225U
Application number: CN202123345598.2U
Authority: CN
Inventors: 毛鹏; 褚俊杰; 段世太
Original assignee: Suzhou Northen Microelectronics Technology Co ltd
Current assignee: Suzhou Northen Microelectronics Technology Co ltd
Priority date: 2021-12-28
Filing date: 2021-12-28
Publication date: 2022-06-28
Anticipated expiration: 2031-12-28

Abstract

The application discloses LED backlight driving power supply device. The LED backlight driving power supply device comprises a Buck converter, a power supply controller, a dimming circuit, an MCU module, a peripheral circuit, a display screen, a key module and a light intensity acquisition module, wherein the input end of the LED backlight driving power supply device is connected with an AC/DC constant voltage source, and the output end of the LED backlight driving power supply device is connected with an LED load. The utility model provides a LED is shaded and drives power supply unit has following beneficial effect: 1) the target light intensity can be set through the keys, and dynamic dimming can be realized according to the difference value between the ambient light intensity and the set light intensity. 2) The dimming circuit adopts closed-loop control, and output current instability caused by load fluctuation or unstable input voltage is avoided. 3) A scheme with high dimming performance is provided, and the light can be accurately dimmed according to a set value.

Description

LED backlight driving power supply device

Technical Field

The utility model relates to a LED high accuracy backlight drive power supply technical field especially relates to a LED backlight drive power supply unit, can realize the luminance automatically regulated of lamp house and adjust luminance the degree of accuracy height.

Background

Nowadays, various light box advertisements, also known as "light box posters" or "night publicity pictures" are seen everywhere, and the application places are distributed on roads, both sides of streets, and public places such as movie (theater) houses, exhibition (sales) shows, commercial downtown areas, stations, airports, docks, parks, and the like. The backlight light source of the lamp box advertisement is usually an LED, if the backlight always keeps high brightness, although the content of the lamp box can be well displayed, the energy waste is large, and the brightness of the LED can be changed according to the requirement in different application occasions and time periods.

In practical applications, the LED backlight driving power supply mostly adopts the LED lighting power supply which is mature in the market. For example, a common bright and weft power supply in the industry (such as a product with the model number of HLG-240H) is supplied by mains supply, constant current output can be realized, the output end of the product is directly connected to the LED, a port of the dimming device is reserved, the port is externally connected with the dimming device, and a knob of the dimming device is rotated to realize the dimming function. When adjusting luminance, can only judge whether adjusting luminance reaches the target value through lamp pearl luminance, and can't realize carrying out closed loop, dynamic adjustment according to the ambient light intensity.

In summary, the following problems still exist in the conventional power supply scheme: 1) only the brightness change of the lamp beads can be seen during dimming, and the current change cannot be known; 2) the dimming circuit is mostly controlled in an open loop mode, and the output current is difficult to ensure to be stable on a certain given value; 3) the traditional dimming method cannot realize the quantitative adjustment of the LED driving current according to the ambient light intensity; 4) the power supply system is usually not intelligent enough and generally does not have a good human-computer interaction function.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a LED drive power supply unit that is shaded, combine the not enough of current multiplexed output power supply unit existence, can adjust luminance according to the accuracy under the different environment, improve the precision of adjusting luminance.

In order to achieve the above object, an embodiment of the present invention provides an LED backlight driving power supply device, an input terminal of which is connected to an AC/DC constant voltage source, and an output terminal of which is connected to an LED load, wherein the LED backlight driving power supply device includes a Buck converter, a power supply controller, a dimming circuit, an MCU module, a peripheral circuit, a display screen, a key module, and a light intensity collecting module; keys in the display screen and key module control the AC/DC constant voltage source to be input to the Buck converter and then output end voltage Vo; the terminal voltage Vo is output to the LED load to emit light; the light intensity acquisition module acquires the luminous intensity of the LED load, generates a feedback signal and inputs the feedback signal to the MCU module and the peripheral circuit; the MCU module and the peripheral circuit output the luminous intensity of the LED load to the display screen in the display screen and the key module; the MCU module and the MCU module in the peripheral circuit send dimming signals to the dimming circuit according to the LED load luminous intensity target value signals arranged in the display screen and the key module; the dimming circuit sends a VDIM signal to the power supply controller according to the dimming signal; the power controller collects sampling signals at the output end of the Buck converter, the power controller superposes the VDIM signals according to the sampling signals, the error processing circuit modulates driving signals of the Buck converter, and the modulated signals are sent to a switching tube of the Buck converter.

Further, the Buck converter comprises a positive electrode access end, a negative electrode access end, a positive electrode end voltage output end Vo + and a negative electrode end voltage output end Vo-; a switching tube Q1 and an inductor L are connected in series between the positive electrode access end and the positive electrode end voltage output end Vo +, and a resistor Rf is connected between the negative electrode access end and the negative electrode end voltage output end Vo-; a switch tube Q2 is connected between the connection node of the switch tube Q1 and the inductor L and the negative electrode access end, and a capacitor C is connected between the positive electrode end voltage output end Vo + and the negative electrode access end; collecting the sampling signal at the voltage output end Vo-of the negative pole end, wherein the signal modulated by the power supply controller comprises a driving signal and a PMW signal, and the PMW signal is a signal obtained by inverting and delaying the driving signal through an inverter and a buffer; the driving signal is input to the switching tube Q1, and the PMW signal is input to the switching tube Q2.

Further, in the power supply controller, the sampling signal and the VDIM signal are input to an input terminal of the power supply controller, the input terminal of the power supply controller is connected with a resistor Rf1 and a resistor Rf2 in series, and one end of the resistor Rf2 is grounded; the resistor Rf1 and the resistor Rf2 are connected to the inverting input terminal of the amplifier U1A, and the reference current Iref is input to the non-inverting input terminal of the amplifier U1A; a circuit ground is formed by connecting a branch composed of a capacitor Cc and a resistor Rc and a capacitor Cc in series in parallel at the output end of the amplifier U1A; the output end of the amplifier U1A is connected to the inverting input end of an amplifier U2A, and a reference voltage Vm is input to the non-inverting input end of the amplifier U2A; the output end of the amplifier U2A outputs a driving signal to the grid electrode of the switch tube Q1; the output end of the amplifier U2A is also connected in series with an inverter and a buffer, and the PMW signal is generated after the drive signal is subjected to inversion and time delay processing through the inverter and the buffer and is input to the gate of the switching tube Q2.

Furthermore, the MCU module and the peripheral circuit comprise an MCU module, a display circuit and a key circuit; the display circuit and the key circuit are both connected with the MCU module, and the light intensity acquisition module inputs the feedback signal generated by the light intensity acquisition module to the MCU module; and the MCU module sends a dimming signal to the dimming circuit.

Furthermore, the display screen and key module comprises keys and a display screen; the LED load luminous intensity target value input by the key is transmitted to the MCU module through the key circuit and then converted into a dimming signal to be sent to the dimming circuit; the MCU module transmits the feedback signal input by the light intensity acquisition module to a display screen through the display circuit.

Further, in the display screen and key module, the key is composed of 4 function keys, and the display screen displays the brightness value or the sampling current value collected by the light intensity collecting module.

Further, in the dimming circuit, the dimming circuit includes a phototransistor QS, a voltage division circuit, a first voltage follower U1B, an RC filter circuit, and a second voltage follower U1C; the voltage division circuit comprises a resistor R1 and a resistor R2 which are arranged in series, the resistor R1 is connected with a driving voltage Vcc, the resistor R2 is grounded, and a connection node of the resistor R1 and the resistor R2 is connected to a non-inverting input end of the first voltage follower U1B and a first electrode of the photosensitive transistor QS; the gate of the photo transistor QS receives the dimming signal; a second electrode of the photo transistor QS is grounded; the RC filter circuit comprises a resistor R3 and a capacitor C1; the output end of the first voltage follower U1B is connected to the non-inverting input end of the second voltage follower U1C through the resistor R3, the non-inverting input end of the second voltage follower U1C is further connected to the ground end of the resistor R2 through the capacitor C1, and the output end of the second voltage follower U1C outputs the VDIM signal to the power controller.

The utility model provides a LED is shaded and drives power supply unit has following beneficial effect: 1) the target light intensity can be set through the keys, and dynamic dimming can be realized according to the difference value between the ambient light intensity and the set light intensity. 2) The dimming circuit adopts closed-loop control, and output current instability caused by load fluctuation or unstable input voltage is avoided. 3) A scheme with high dimming performance is provided, and the light can be accurately dimmed according to a set value.

Drawings

The technical solution and other advantages of the present application will be presented in the following detailed description of specific embodiments of the present application with reference to the accompanying drawings.

Fig. 1 is a schematic circuit structure diagram of an LED backlight driving power supply device according to an embodiment of the present disclosure.

Fig. 2 is a schematic circuit diagram of a Buck converter according to an embodiment of the present disclosure.

Fig. 3 is a schematic circuit structure diagram of a power supply controller according to an embodiment of the present application.

Fig. 4 is a schematic circuit structure diagram of a dimming circuit according to an embodiment of the present application.

Fig. 5 is a schematic circuit structure diagram of an MCU module and a peripheral circuit provided in the embodiment of the present application.

Fig. 6 is a schematic diagram of a key and a display module according to an embodiment of the present disclosure.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It is to be understood that the embodiments described are only a few embodiments of the present application and not all 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 application.

In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.

The following disclosure provides many different embodiments or examples for implementing different features of the application. In order to simplify the disclosure of the present application, specific example components and arrangements are described below. Of course, they are merely examples and are not intended to limit the present application. Moreover, the present application may repeat reference numerals and/or letters in the various examples, such repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. In addition, examples of various specific processes and materials are provided herein, but one of ordinary skill in the art may recognize applications of other processes and/or use of other materials.

The utility model relates to a LED is shaded and is driven power supply unit can adjust luminance accurately, include following part: buck converter, power controller, dimmer circuit, MCU module and peripheral circuit, display and button module.

1) Buck converter: the front-stage constant voltage source is used for providing input for the rear-stage synchronous Buck converter, a constant current control mode is adopted, and a PWM (pulse width modulation) driving signal is output and sent to the Buck converter after the sampling current is sent to the power supply controller.

2) A power supply controller: the input signal of the power controller is composed of a sampling current value and a VDIM (vehicle dynamic integrated management system), the two signals are superposed in a certain proportion and then sent to an error processing link, and a PWM modulation circuit outputs PWM driving signals to Q1 and Q2 of a Buck converter according to the error processing.

3) The dimming circuit: the PWM signal of the dimming circuit is sent by the MCU module, the MCU module carries out conversion according to the key input value, and closed-loop control is realized according to the sampling value and the input reference value. A voltage follower is added in front of an RC (current limiting resistor) filter circuit, so that the front voltage dividing circuit and the filter circuit can be isolated, the influence of the filter resistance on the front voltage dividing circuit is greatly reduced, and the accuracy of the input voltage of the filter circuit is further improved.

4) MCU module and peripheral circuit: the MCU-based control circuit comprises a key circuit and a display circuit. Signals of the light intensity acquisition module are processed and then input into the MCU, the MCU is compared with a target set by the key circuit, the signals are converted into PWM signals and sent to the light modulation circuit switch tube Q1, and the output value of real-time sampling can be transmitted to the display screen through the sampling circuit and the display circuit.

5) Display screen and button module: the key consists of 4 function keys, and can set output dimming brightness; the display circuit is connected with the key circuit and the MCU, so that the real-time sampling current value can be displayed.

Specifically, as shown in fig. 1 to 6, the input end of the LED backlight driving power supply device is connected to an AC/DC constant voltage source, and the output end thereof is connected to an LED load, which includes a Buck converter, a power supply controller, a dimming circuit, an MCU module and a peripheral circuit, a display screen and key module, and a light intensity collecting module.

As shown in fig. 1, a key in the display screen and key module controls the AC/DC constant voltage source to input the voltage Vo at the output end of the Buck converter; the terminal voltage Vo is output to the LED load to emit light; the light intensity acquisition module acquires the luminous intensity of the LED load, generates a feedback signal and inputs the feedback signal to the MCU module and the peripheral circuit; the MCU module and the peripheral circuit output the luminous intensity of the LED load to the display screen in the display screen and the key module; the MCU module and the MCU module in the peripheral circuit send dimming signals to the dimming circuit according to the LED load luminous intensity target value signals arranged in the display screen and the key module; the dimming circuit sends a VDIM signal to the power supply controller according to the dimming signal; the power controller collects sampling signals at the output end of the Buck converter, the power controller superposes the VDIM signals according to the sampling signals, the error processing circuit modulates driving signals of the Buck converter, and the modulated signals are sent to a switching tube of the Buck converter.

As shown in fig. 2, further, the Buck converter includes a positive terminal, a negative terminal, a positive terminal voltage output terminal Vo +, and a negative terminal voltage output terminal Vo-; a switching tube Q1 and an inductor L are connected in series between the positive electrode access end and the positive electrode end voltage output end Vo +, and a resistor Rf is connected between the negative electrode access end and the negative electrode end voltage output end Vo-; a switch tube Q2 is connected between the connection node of the switch tube Q1 and the inductor L and the negative electrode access end, and a capacitor C is connected between the positive electrode end voltage output end Vo + and the negative electrode access end; collecting the sampling signal at the voltage output end Vo-of the negative pole end, wherein the signal modulated by the power supply controller comprises a driving signal and a PMW signal, and the PMW signal is a signal obtained by inverting and delaying the driving signal through an inverter and a buffer; the driving signal is input to the switching tube Q1, and the PMW signal is input to the switching tube Q2.

As shown in fig. 3, further, in the power controller, the sampling signal and the VDIM signal are input to an input terminal of the power controller, the input terminal of the power controller is connected in series with a resistor Rf1 and a resistor Rf2, and one end of the resistor Rf2 is grounded; the resistor Rf1 and the resistor Rf2 are connected to the inverting input terminal of the amplifier U1A, and the reference current Iref is input to the non-inverting input terminal of the amplifier U1A; a circuit ground is formed by connecting a branch composed of a capacitor Cc and a resistor Rc and a capacitor Cc in series in parallel at the output end of the amplifier U1A; the output end of the amplifier U1A is connected to the inverting input end of an amplifier U2A, and a reference voltage Vm is input to the non-inverting input end of the amplifier U2A; the output end of the amplifier U2A outputs a driving signal to the grid electrode of the switch tube Q1; the output end of the amplifier U2A is also connected in series with an inverter and a buffer, and the PMW signal is generated after the drive signal is subjected to inversion and time delay processing through the inverter and the buffer and is input to the gate of the switching tube Q2.

As shown in fig. 5, further, the MCU module and the peripheral circuit include an MCU module, a display circuit and a key circuit; the display circuit and the key circuit are both connected with the MCU module, and the light intensity acquisition module inputs the feedback signal generated by the light intensity acquisition module to the MCU module; the MCU module sends a dimming signal to the dimming circuit.

As shown in fig. 6, further, the display screen and key module includes keys and a display screen; the LED load luminous intensity target value input by the key is transmitted to the MCU module through the key circuit and then converted into a dimming signal to be sent to the dimming circuit; the MCU module transmits the feedback signal input by the light intensity acquisition module to a display screen through the display circuit.

As shown in fig. 6, further, in the display screen and key module, the key is composed of 4 function keys, and the display screen displays the brightness value or the sampling current value collected by the light intensity collecting module.

As shown in fig. 4, further, in the dimming circuit, the dimming circuit includes a phototransistor QS, a voltage dividing circuit, a first voltage follower U1B, an RC filter circuit, and a second voltage follower U1C; the voltage division circuit comprises a resistor R1 and a resistor R2 which are arranged in series, the resistor R1 is connected with a driving voltage Vcc, the resistor R2 is grounded, and a connection node of the resistor R1 and the resistor R2 is connected to a non-inverting input end of the first voltage follower U1B and a first electrode of the photosensitive transistor QS; the gate of the photo transistor QS receives the dimming signal; a second electrode of the photo transistor QS is grounded; the RC filter circuit comprises a resistor R3 and a capacitor C1; the output end of the first voltage follower U1B is connected to the non-inverting input end of the second voltage follower U1C through the resistor R3, the non-inverting input end of the second voltage follower U1C is further connected to the ground end of the resistor R2 through the capacitor C1, and the output end of the second voltage follower U1C outputs the VDIM signal to the power controller.

The utility model provides a LED drive power supply device in a poor light has following beneficial effect: 1) the target light intensity can be set through the keys, and dynamic dimming can be realized according to the difference value between the ambient light intensity and the set light intensity. 2) The dimming circuit adopts closed-loop control, and output current instability caused by load fluctuation or unstable input voltage is avoided. 3) A scheme with high dimming performance is provided, and the light can be accurately dimmed according to a set value.

The external DC power supply of this scheme is the power supply of Buck converter, connects this power supply unit's output LED load simultaneously, presses "power" button to supply power. After the direct current power supply normally supplies power, a dimming target value is set through the key, and the MCU is dynamically adjusted through a feedback signal of the light intensity acquisition module to send a PWM signal of the dimming circuit. After receiving the PWM dimming signal sent by the MCU, the dimming circuit outputs a VDIM value after voltage division, isolation and filtering processing of the dimming circuit. At the moment, a current sampling signal input by the power supply control circuit is superposed with a VDIM signal, and the Buck circuit driving signal is modulated after error processing. Because of the synchronous Buck circuit, the modulated driving signals are respectively sent to the Buck power switch tube after being subjected to phase inversion and time delay processing. The real-time current value can be displayed on the display module through the MCU module and the peripheral circuit. The illumination acquisition module continuously acquires the light intensity, and after the light intensity is fed back to the MCU module, automatic closed-loop dimming can be realized according to the difference with the target value, so that the dimming accuracy is ensured.

In the foregoing embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.

The above embodiments of the present application are described in detail, and specific examples are applied in the present application to explain the principles and implementations of the present application, and the description of the above embodiments is only used to help understand the technical solutions and core ideas of the present application; those of ordinary skill in the art will understand that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications or substitutions do not depart from the spirit and scope of the present disclosure as defined by the appended claims.

Claims

1. An LED backlight driving power supply device is characterized by comprising a Buck converter, a power supply controller, a dimming circuit, an MCU module, a peripheral circuit, a display screen, a key module and a light intensity acquisition module, wherein the input end of the LED backlight driving power supply device is connected with an AC/DC constant voltage source, and the output end of the LED backlight driving power supply device is connected with an LED load;

keys in the display screen and key module control the AC/DC constant voltage source to be input to the Buck converter and then output end voltage Vo; the terminal voltage Vo is output to the LED load to emit light;

the light intensity acquisition module acquires the luminous intensity of the LED load, generates a feedback signal and inputs the feedback signal to the MCU module and the peripheral circuit;

the MCU module and the peripheral circuit output the luminous intensity of the LED load to the display screen in the display screen and the key module;

the MCU module and the MCU module in the peripheral circuit send dimming signals to the dimming circuit according to the LED load luminous intensity target value signals arranged in the display screen and the key module;

the dimming circuit sends a VDIM signal to the power supply controller according to the dimming signal;

the power controller collects sampling signals at the output end of the Buck converter, the power controller superposes the VDIM signals according to the sampling signals, the error processing circuit modulates driving signals of the Buck converter, and the modulated signals are sent to a switching tube of the Buck converter.

2. The LED backlight driving power supply device according to claim 1, wherein the Buck converter includes a positive terminal input, a negative terminal input, a positive terminal voltage output Vo +, a negative terminal voltage output Vo-;

a switching tube Q1 and an inductor L are connected in series between the positive electrode access end and the positive electrode end voltage output end Vo +, and a resistor Rf is connected between the negative electrode access end and the negative electrode end voltage output end Vo-;

a switch tube Q2 is connected between the connection node of the switch tube Q1 and the inductor L and the negative electrode access end, and a capacitor C is connected between the positive electrode end voltage output end Vo + and the negative electrode access end;

collecting the sampling signal at the voltage output end Vo-of the negative pole end, wherein the signal modulated by the power supply controller comprises a driving signal and a PMW signal, and the PMW signal is a signal obtained by inverting and delaying the driving signal through an inverter and a buffer; the driving signal is input to the switching tube Q1, and the PMW signal is input to the switching tube Q2.

3. The LED backlight driving power supply device according to claim 2, wherein, in the power supply controller,

the sampling signal and the VDIM signal are input into an input end of the power supply controller, the input end of the power supply controller is connected with a resistor Rf1 and a resistor Rf2 in series, and one end of the resistor Rf2 is grounded; the inverting input end of the amplifier U1A is connected between the resistor Rf1 and the resistor Rf2, and a reference current Iref is input to the non-inverting input end of the amplifier U1A;

a circuit ground is formed by connecting a branch composed of a capacitor Cc and a resistor Rc and a capacitor Cc in series in parallel at the output end of the amplifier U1A; the output end of the amplifier U1A is connected to the inverting input end of an amplifier U2A, and a reference voltage Vm is input to the non-inverting input end of the amplifier U2A; the output end of the amplifier U2A outputs a driving signal to the grid electrode of the switch tube Q1;

the output end of the amplifier U2A is also connected in series with an inverter and a buffer, and the PMW signal is generated by the drive signal after being subjected to inversion and delay processing through the inverter and the buffer and then is input to the gate of the switching tube Q2.

4. The LED backlight driving power supply device according to claim 1, wherein the MCU module and the peripheral circuit comprise an MCU module, a display circuit and a key circuit; the display circuit and the key circuit are both connected with the MCU module, and the light intensity acquisition module inputs the feedback signal generated by the light intensity acquisition module to the MCU module; and the MCU module sends a dimming signal to the dimming circuit.

5. The LED backlight driving power supply device according to claim 4, wherein the display screen and key module comprises a key and a display screen; the LED load luminous intensity target value input by the key is transmitted to the MCU module through the key circuit and then converted into a dimming signal to be sent to the dimming circuit; the MCU module transmits the feedback signal input by the light intensity acquisition module to a display screen through the display circuit.

6. The LED backlight driving power supply device according to claim 5, wherein the keys of the display screen and key module are composed of 4 function keys, and the display screen displays the brightness value or the sampling current value collected by the light intensity collecting module.

7. The LED backlight driving power supply device according to claim 1, wherein, in the dimming circuit,

the dimming circuit comprises a photosensitive transistor QS, a voltage division circuit, a first voltage follower U1B, an RC filter circuit and a second voltage follower U1C;

the voltage division circuit comprises a resistor R1 and a resistor R2 which are arranged in series, the resistor R1 is connected with a driving voltage Vcc, the resistor R2 is grounded, and a connection node of the resistor R1 and the resistor R2 is connected to a non-inverting input end of the first voltage follower U1B and a first electrode of the photosensitive transistor QS; the gate of the photo transistor QS receives the dimming signal; a second electrode of the photo transistor QS is grounded; the RC filter circuit comprises a resistor R3 and a capacitor C1; the output end of the first voltage follower U1B is connected to the non-inverting input end of the second voltage follower U1C through the resistor R3, the non-inverting input end of the second voltage follower U1C is further connected to the ground end of the resistor R2 through the capacitor C1, and the output end of the second voltage follower U1C outputs the VDIM signal to the power controller.