CN112382243A - Driving circuit and method, backlight plate and display device - Google Patents
Driving circuit and method, backlight plate and display device Download PDFInfo
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- CN112382243A CN112382243A CN202011282068.5A CN202011282068A CN112382243A CN 112382243 A CN112382243 A CN 112382243A CN 202011282068 A CN202011282068 A CN 202011282068A CN 112382243 A CN112382243 A CN 112382243A
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
- G09G3/3406—Control of illumination source
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2320/00—Control of display operating conditions
- G09G2320/02—Improving the quality of display appearance
- G09G2320/0233—Improving the luminance or brightness uniformity across the screen
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Abstract
The embodiment of the invention provides a driving circuit and a method, a backlight plate and a display device, wherein the driving circuit comprises: the device comprises a voltage stabilizing module, a first lamp string and a first current regulating module; the output end of the voltage stabilizing module is connected with the first end of the first lamp string, and the second end of the first lamp string is connected with the first current regulating module; the voltage stabilizing module is used for generating a constant voltage through voltage feedback and taking the constant voltage as the power supply voltage of the first lamp string; the first current adjusting module is used for collecting the first driving current flowing through the first lamp string and adjusting the first driving current according to the comparison result of the first driving current and the reference signal. The driving circuit provided by the embodiment can enable the currents of different lamp strings to be consistent, so that the brightness uniformity of the backlight plate and the visual effect of the display screen are improved.
Description
Technical Field
The embodiment of the invention relates to the technical field of voltage conversion, in particular to a driving circuit and method, a backlight plate and a display device.
Background
A backlight, which is a light source device for ensuring the brightness of the back of the display screen, is required to be provided in the display device. The brightness uniformity of the light emitted from the backlight is an important factor in determining the visual effect of the display screen.
In the prior art, an LED driving circuit of a backlight generally adopts a constant voltage mode to perform boost conversion on an input voltage to obtain a constant voltage, and the constant voltage provides a power supply for each LED string in a light emitting module to enable the LED light emitting module to emit light.
However, since the internal resistance of each LED is different, different LED strings may have inconsistent current under the driving of constant voltage, so that the light emitted from the backlight has poor brightness, which affects the visual effect of the display screen.
Disclosure of Invention
The embodiment of the invention provides a driving circuit and method, a backlight plate and a display device, which are used for improving the brightness uniformity of the backlight plate and the visual effect of a display screen.
In a first aspect, an embodiment of the present invention provides a driving circuit, including: the device comprises a voltage stabilizing module, a first lamp string and a first current regulating module;
the output end of the voltage stabilizing module is connected with the first end of the first lamp string, and the second end of the first lamp string is connected with the first current regulating module;
the voltage stabilizing module is used for generating a constant voltage through voltage feedback and taking the constant voltage as the power supply voltage of the first lamp string;
the first current adjusting module is used for collecting a first driving current flowing through the first lamp string and adjusting the first driving current according to a comparison result of the first driving current and a reference signal.
In one possible design, the first current regulation module includes: the current sampling circuit comprises a triode, a bias resistor, a current sampling resistor and a voltage stabilizing tube;
the collector of the triode is connected with the second end of the first lamp string and is connected with the base through the bias resistor, and the emitter of the triode is connected with one end of the current sampling resistor and the voltage stabilizing end of the voltage stabilizing tube; the other end of the current sampling resistor is grounded; the cathode of the voltage stabilizing tube is connected with the base electrode of the triode, and the anode of the voltage stabilizing tube is grounded;
the voltage regulator tube is used for comparing the first driving current sampled by the current sampling module with a reference signal and sending a comparison result to the triode;
and the triode is used for regulating the first driving current according to the comparison result.
In one possible design, the current feedback module further includes: an overvoltage protection module;
and one end of the overvoltage protection module is connected with the cathode of the voltage stabilizing tube, and the other end of the overvoltage protection module is grounded and is used for performing overvoltage protection on the voltage stabilizing tube.
In one possible design, the overvoltage protection module includes a first diode;
and the cathode of the first diode is connected with the cathode of the voltage stabilizing tube, and the anode of the first diode is grounded.
In one possible design, the first current regulation module further includes: a feedback resistor;
one end of the feedback resistor is connected with the cathode of the voltage stabilizing tube, and the other end of the feedback resistor is connected with the feedback end of the controller of the voltage stabilizing module;
the voltage stabilizing module is used for generating a PWM signal according to a feedback signal of the feedback resistor through the controller and generating an output voltage according to the PWM signal so as to regulate a first driving current flowing through the first lamp string.
In one possible design, the driving circuit further includes: the second lamp string and the second current regulating module;
the first end of the second lamp string is connected with the output end of the voltage stabilizing module, and the other end of the second lamp string is connected with the second current regulating module;
the second current adjusting module is used for collecting a second driving current flowing through the second lamp string and adjusting the second driving current according to a comparison result of the second driving current and a reference signal.
In one possible embodiment, the voltage regulation module is a voltage boost module or a voltage buck module.
In one possible design, the voltage stabilizing module is a boosting module, and the voltage stabilizing module comprises an input capacitor, an inductor, a freewheeling diode, an output capacitor, a switching tube controller and a voltage sampling unit;
one end of the inductor is connected with the input capacitor, and the other end of the inductor is connected with the first end of the switch tube and the anode of the freewheeling diode; the cathode of the freewheeling diode is connected with the output capacitor and the first end of the voltage sampling unit; the second end of the voltage sampling unit is grounded, and the output end of the voltage sampling unit is connected with the feedback end of the controller; the output end of the controller is connected with the control end of the switch tube; the first end of the switch tube is connected with the anode of the freewheeling diode, and the second end of the switch tube is grounded;
the input capacitor is used for stabilizing the input voltage;
the inductor is used for storing electric energy;
the freewheeling diode is used for freewheeling when the electric energy stored by the inductor is released to the output capacitor;
the switch tube is used for receiving the PWM signal output by the controller and conducting or disconnecting according to the PWM signal;
the voltage sampling unit is used for sampling the output voltage and feeding back the sampling voltage to the feedback end of the controller, so that the controller generates the PWM signal according to the sampling voltage.
In a second aspect, an embodiment of the present invention provides a driving method, including: the voltage stabilizing module generates a constant voltage through voltage feedback, and the constant voltage is used as the power supply voltage of the first lamp string;
the first current adjusting module collects a first driving current flowing through the first lamp string and adjusts the first driving current according to a comparison result of the first driving current and a reference signal.
In one possible design, the first current regulation module includes: the current sampling circuit comprises a triode, a bias resistor, a current sampling resistor and a voltage stabilizing tube; the collector of the triode is connected with the second end of the first lamp string and is connected with the base through the bias resistor, and the emitter of the triode is connected with one end of the current sampling resistor and the voltage stabilizing end of the voltage stabilizing tube; the other end of the current sampling resistor is grounded; the cathode of the voltage stabilizing tube is connected with the base electrode of the triode, and the anode of the voltage stabilizing tube is grounded; the method further comprises the following steps:
the voltage-stabilizing tube compares the first driving current sampled by the current sampling module with a reference signal and sends a comparison result to the triode;
and the triode regulates the first driving current according to the comparison result.
In one possible design, the first current regulation module further includes a feedback resistor, one end of the feedback resistor is connected with the cathode of the voltage regulator tube, and the other end of the feedback resistor is connected with the feedback end of the controller of the voltage regulator module; the method further comprises the following steps:
the controller generates a PWM signal according to a feedback signal of the feedback resistor;
the voltage stabilizing module generates output voltage according to the PWM signal so as to regulate first driving current flowing through the first lamp string.
In a third aspect, embodiments of the present invention provide a backlight panel, including the driving circuit according to the first aspect and various possible designs of the first aspect.
In a fourth aspect, embodiments of the present invention provide a display device, including the backlight panel according to the third aspect.
The driving circuit and method, backlight panel and display device provided by the embodiment comprise: the device comprises a voltage stabilizing module, a first lamp string and a first current regulating module; the output end of the voltage stabilizing module is connected with the first end of the first lamp string, and the second end of the first lamp string is connected with the first current regulating module; the voltage stabilizing module is used for generating a constant voltage through voltage feedback and taking the constant voltage as the power supply voltage of the first lamp string; the first current adjusting module is used for collecting a first driving current flowing through the first lamp string and adjusting the first driving current according to a comparison result of the first driving current and a reference signal. The driving circuit provided by the embodiment monitors the current by connecting the current sampling resistor on the lamp string in series on the basis of the constant voltage mode, compares the monitored current with the reference voltage of the voltage stabilizing tube, and adjusts the driving current passing through the lamp string according to the comparison result, so that the currents of different lamp strings tend to be consistent, and the brightness uniformity of the backlight plate and the visual effect of the display screen are improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a circuit diagram of a driving circuit in a constant voltage mode according to an embodiment of the present invention;
fig. 2 is a circuit diagram of a driving circuit according to an embodiment of the invention;
fig. 3 is a circuit schematic diagram of a constant current mode driving circuit according to an embodiment of the present invention;
fig. 4 is a circuit diagram of a driving circuit according to another embodiment of the invention;
fig. 5 is a circuit diagram of a driving circuit according to another embodiment of the invention;
fig. 6 is a circuit diagram of a driving circuit according to another embodiment of the invention;
fig. 7 is a circuit diagram of a driving circuit according to another embodiment of the invention;
fig. 8 is a circuit diagram of a driving circuit according to another embodiment of the invention.
Reference numerals:
an input capacitance C1; an inductance L; a freewheel diode D1; an output capacitor C2; a switching tube Q1; a first resistor R1; a second resistor R2; first light string LEDs 1; second light string LEDs 2; a controller 11; inputting a voltage VIN; an output voltage VOUT; a voltage stabilizing module 10; a first current regulation module 20; a transistor Q2; a sampling resistor R3; a bias resistor R4; a voltage regulator tube RG 1; a first diode D2; a feedback terminal FB; a feedback resistor R5; a second current regulation module 30.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, 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 some, but not all, embodiments of the present invention. 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.
Fig. 1 is a circuit diagram of a constant voltage mode driving circuit according to an embodiment of the present invention. As shown in fig. 1, the input capacitor C1, the inductor L, the freewheeling diode D1, the output capacitor C2, the switching tube Q1, the controller 11, the first resistor R1 and the second resistor R2 form a boost module, and the boost module is configured to boost the input voltage VIN to obtain a constant output voltage VOUT, and use VOUT as a power supply voltage of the light emitting module. The light module includes a first string of LEDs1 and a second string of LEDs 2.
In a specific implementation process, the controller 10 generates a PWM signal according to the sampled voltage of the output voltage VOUT sampled by the first resistor R1 and the second resistor R2, and controls the on and off of the switching tube Q1 through the PWM signal to obtain the output voltage VOUT higher than VIN, so as to supply power to the light emitting module. Specifically, assuming that the switching tube Q1 is turned off for a certain time, the voltage of the output capacitor is equal to the input voltage, and then the voltage is boosted through the charging phase and the discharging phase in sequence. During the charging phase, the switch Q1 is turned on, the input voltage VIN flows through the inductor L, and the freewheeling diode D1 prevents the capacitor from discharging to ground. Since the input voltage VIN is a dc voltage, the current on the inductor L linearly increases at a certain rate, and the inductor L stores energy as the inductor current increases. In the discharging stage, the switching tube Q1 is turned off, and the current flowing through the inductor L does not suddenly disappear due to the current holding characteristic of the inductor L, but slowly gradually decreases from the highest value at the end of charging to 0. When the inductor L is turned off, the freewheeling diode D1 allows freewheeling, so the inductor L starts to charge the output capacitor C2, and the voltage across the output capacitor C2 increases, and the output voltage VOUT is higher than the input voltage VIN. The boosting effect is realized.
It can be seen that VOUT can be maintained at a constant value through voltage feedback of R1 and R2 and control of the controller 10, however, since the internal resistances of the LEDs are different, the sum of the internal resistances of the first string and the second string of LEDs may also be different, and thus the currents generated by the first string and the second string of LEDs with different internal resistances are different under the same constant voltage. The light emitted by the backlight plate has poor brightness, and the visual effect of the display screen is influenced.
In view of the above problems, the inventors have found that current monitoring can be performed by connecting a current sampling resistor in series to a string of lights on the basis of a constant voltage mode, and that currents of different strings of lights can be made to be consistent by comparing the monitored current with a reference voltage of a voltage regulator tube and adjusting a driving current flowing through the string of lights according to a comparison result.
The technical solution of the present invention will be described in detail below with specific examples. The following several specific embodiments may be combined with each other, and details of the same or similar concepts or processes may not be repeated in some embodiments.
Fig. 2 is a circuit schematic diagram of a driving circuit according to an embodiment of the present invention, as shown in fig. 1, the driving circuit includes: a voltage stabilization module 10, a first string of lights LEDs1, and a first current regulation module 20.
The output terminal of the voltage regulator module 10 is connected to the first terminal of the first string LEDs1, and the second terminal of the first string LEDs1 is connected to the first current regulating module 20.
The voltage stabilizing module 10 is used for generating a constant voltage through voltage feedback and using the constant voltage as a power supply voltage of the first string LEDs 1.
The first current adjusting module 20 is configured to collect the first driving current flowing through the first string of LEDs1 and adjust the first driving current according to a comparison result between the first driving current and the reference signal.
In this embodiment, the voltage stabilizing module 10 may be a voltage boosting module or a voltage reducing module. The present embodiment is not limited to this, as long as a constant voltage can be supplied by voltage feedback adjustment.
In practical application, the driving circuit may include a plurality of light strings, and each light string is correspondingly provided with a current adjusting module, so that the working currents of the light strings tend to be consistent, and the brightness uniformity of the backlight plate is improved.
The working process of the driving circuit provided by the embodiment is as follows: the voltage regulator module 10 generates a constant voltage through voltage feedback and supplies the constant voltage as a power supply voltage for the first string LEDs1 to power the first string LEDs 1. The first string LEDs1 emit light under the action of a constant voltage, the first current adjusting module 20 corresponding to the first string LEDs1 collects the first driving current of the first string LEDs1, compares the collected first driving current with the reference signal, and adjusts the first driving current according to the comparison result, so that the first driving current and the reference signal tend to be consistent. Similarly, for other light strings, the driving currents of other light strings can be adjusted to be consistent with the reference signal through the current adjusting modules corresponding to the other light strings, so that the light emitting brightness of each light string is consistent, and the brightness uniformity of the backlight plate is improved.
Fig. 3 is a circuit schematic diagram of a constant current mode driving circuit according to an embodiment of the present invention. As shown in fig. 3, the driving circuit includes: the LED lamp comprises an input capacitor C1, an inductor L, a freewheeling diode D1, an output capacitor C2, a switching tube Q1, a controller 11, a boosting module consisting of a first resistor R1 and a second resistor R2, and a light-emitting module consisting of a first string of lights 1 and a second string of lights 2. The driving current of the first light string LEDs1 is collected through the resistor R9 by arranging the switch tube Q4 and the resistor R9 in series with the first light string LEDs1, and the driving current is sent to the constant current chip for analysis so as to generate the PWM signal to control the switch tube Q4 to be turned on and off, thereby adjusting the driving current, and similarly, the driving current of the second light string LEDs2 is adjusted through arranging the resistor R10 and the switch tube Q5 for the second light string LEDs 2. And feeds back the current feedback result to the controller 11, so that the controller 11 generates a PWM signal to control the switching tube Q1 to generate a corresponding output voltage VOUT. Therefore, the driving circuit in the constant current mode needs to adopt an additional constant current chip to adjust the current, the cost is high, the circuit connection is complex, the driving circuit provided by the embodiment can adjust the driving current only through the current adjusting module corresponding to each lamp string to compare the driving current with the reference signal, and compared with the prior art shown in fig. 3, the driving circuit can reduce the cost and has a simple circuit.
The driving circuit provided by the embodiment comprises: a voltage stabilization module 10, a first string of lights LEDs1 and a first current regulation module 20; the output end of the voltage stabilizing module 10 is connected with the first end of the first string LEDs1, and the second end of the first string LEDs1 is connected with the first current adjusting module 20; the voltage stabilizing module 10 is used for generating a constant voltage through voltage feedback, and the constant voltage is used as a power supply voltage of the first string LEDs 1; the first current adjusting module 20 is configured to collect the first driving current flowing through the first string of LEDs1 and adjust the first driving current according to a comparison result between the first driving current and the reference signal. The driving circuit provided by the embodiment monitors the current by connecting the current sampling resistor R3 on the string lights in series on the basis of the constant voltage mode, compares the monitored current with the reference voltage of the voltage stabilizing tube, and adjusts the driving current passing through the string lights according to the comparison result, so that the currents of different string lights tend to be consistent, thereby improving the brightness uniformity of the backlight plate and the visual effect of the display screen.
Fig. 4 is a circuit schematic diagram of a driving circuit according to another embodiment of the present invention, and as shown in fig. 4, based on the embodiment shown in fig. 2, the structure of the first current regulating module 20 is explained in detail in this embodiment. In this embodiment, the first current regulation module 20 includes: the circuit comprises a triode Q2, a bias resistor R4, a current sampling resistor R3 and a voltage regulator tube RG 1.
The collector of the triode Q2 is connected with the second end of the first light string LEDs1 and is connected with the base through a bias resistor R4, and the emitter is connected with one end of a current sampling resistor R3 and the voltage-stabilizing end of a voltage-stabilizing tube RG 1; the other end of the current sampling resistor R3 is grounded; the cathode of the voltage regulator tube RG1 is connected with the base of the triode Q2, and the anode is grounded.
And the voltage regulator tube RG1 is used for comparing the first driving current sampled by the current sampling module with a reference signal and sending a comparison result to the triode Q2.
And a transistor Q2 for adjusting the first driving current according to the comparison result.
In this embodiment, the specific model of the voltage regulator RG1 is not specifically limited in this embodiment, and the voltage regulator RG1 only has three ports, namely an anode port, a cathode port and a voltage stabilizing port, and can compare a voltage signal obtained by converting a current signal sampled by the sampling resistor R3 with a reference voltage. Alternatively, the model of the voltage regulator tube RG1 may be AZ 431-A.
In a specific operation process, the voltage regulator module 10 generates a constant voltage through voltage feedback, and supplies the constant voltage as a power voltage of the first string LEDs1 to the first string LEDs 1. The first string LEDs1 emit light under the action of a constant voltage, the sampling resistor R3 in the first current adjusting module 20 corresponding to the first string LEDs1 collects the first driving current of the first string LEDs1, the voltage regulator RG1 compares the collected first driving current with a reference signal, and the triode Q2 and the bias resistor R4 adjust the first driving current according to the comparison result, so that the first driving current and the reference signal tend to be consistent. Similarly, for other light strings, the driving currents of other light strings can be adjusted to be consistent with the reference signal through the current adjusting modules corresponding to the other light strings, so that the light emitting brightness of each light string is consistent, and the brightness uniformity of the backlight plate is improved.
The driving circuit provided by this embodiment collects the first driving current flowing through the first string LEDs1 through the sampling resistor R3, and sends the first driving current to the voltage regulator RG1, compares the first driving current with the reference signal through the voltage regulator RG1, and sends the comparison result to the triode Q2, and adjusts the first driving current according to the comparison result through the triode Q2 and the bias resistor R4 so that the driving current and the reference signal tend to be consistent, thereby making the currents of different strings tend to be consistent, and further improving the brightness uniformity of the backlight board, and the visual effect of the display screen.
Optionally, in order to protect the voltage regulator RG1, in a specific embodiment, an overvoltage protection module is additionally provided, as shown in fig. 5, the current feedback module further includes: an overvoltage protection module; and one end of the overvoltage protection module is connected with the cathode of the voltage regulator tube RG1, and the other end of the overvoltage protection module is grounded and is used for performing overvoltage protection on the voltage regulator tube RG 1.
The overvoltage protection module comprises a first diode D2; the cathode of the first diode D2 is connected to the cathode of the regulator RG1, and the anode is grounded.
The driving circuit provided by the embodiment can avoid breakdown of the voltage regulator tube RG1 in the current regulation module by arranging the overvoltage protection module, and ensures normal operation of the circuit.
Fig. 6 is a circuit schematic diagram of a driving circuit according to yet another embodiment of the present invention, as shown in fig. 6, on the basis of the above embodiment, for example, on the basis of the embodiment shown in fig. 5, in order to increase the adjustment range of the driving current of the strings of lights and further ensure that the currents of the strings of lights tend to be consistent, a feedback resistor R5 is additionally provided in this embodiment, so as to feed back the comparison result of the sampled driving current and the reference signal to the controller 11 of the voltage stabilizing module 10, and the output constant voltage is adjusted by combining with the voltage feedback. Specifically, in this embodiment, the first current adjusting module 20 further includes: feedback resistor R5.
One end of the feedback resistor R5 is connected to the cathode of the regulator tube RG1, and the other end is connected to the feedback terminal FB of the controller 11 of the regulator module 10.
The voltage stabilizing module 10 is configured to generate a PWM signal according to a feedback signal of the feedback resistor R5 through the controller 11, and generate an output voltage VOUT according to the PWM signal, so as to regulate a first driving current flowing through the first string LEDs 1.
In a specific operation process, the voltage regulator module 10 generates a constant voltage through voltage feedback, and supplies the constant voltage as a power voltage of the first string LEDs1 to the first string LEDs 1. The first string LEDs1 emit light under the action of a constant voltage, the sampling resistor R3 in the first current adjusting module 20 corresponding to the first string LEDs1 collects the first driving current of the first string LEDs1, the voltage regulator RG1 compares the collected first driving current with a reference signal, and the triode Q2 and the bias resistor R4 adjust the first driving current according to the comparison result, so that the first driving current and the reference signal tend to be consistent. In view of the limited adjustment range of the driving current through the transistor Q2 and the bias resistor R4, the feedback resistor R5 is added, the comparison result is sent to the controller 11 of the voltage stabilizing module 10 through the feedback resistor R5, so that the controller 11 generates a PWM signal according to the comparison result and a voltage feedback signal, and sends the PWM signal to the switching tube Q1, and a constant voltage is output through control and adjustment of the switching tube Q1. Thereby providing a greater range of drive current adjustment for the LEDs1 of the first string of lights. Similarly, for other light strings, the driving currents of other light strings can be adjusted to be consistent with the reference signal through the current adjusting modules corresponding to the other light strings, so that the light emitting brightness of each light string is consistent, and the brightness uniformity of the backlight plate is improved.
The driving voltage provided by the embodiment is adjusted by combining current feedback and voltage feedback through additionally arranging the feedback resistor R5, so that the adjusting range of the driving current of the lamp strings can be further enlarged, the currents of different lamp strings tend to be consistent, and the brightness uniformity of the backlight plate and the visual effect of the display screen are improved.
Fig. 7 is a circuit diagram of a driving circuit according to another embodiment of the present invention, as shown in fig. 7, based on the embodiment shown in fig. 6, in this embodiment, a detailed description is given of a specific result of the voltage stabilizing module 10, specifically, the voltage stabilizing module 10 is a voltage boosting module, and the voltage stabilizing module 10 includes an input capacitor C1, an inductor L, a freewheeling diode D1, an output capacitor C2, a switching tube Q1, a controller 11, and a voltage sampling unit.
One end of the inductor L is connected with the input capacitor C1, and the other end of the inductor L is connected with the first end of the switching tube Q1 and the anode of the freewheeling diode D1; the cathode of the freewheeling diode D1 is connected with the output capacitor C2 and the first end of the voltage sampling unit; the second end of the voltage sampling unit is grounded, and the output end of the voltage sampling unit is connected with the feedback end FB of the controller 11; the output end of the controller 11 is connected with the control end of the switching tube Q1; the switching tube Q1 has a first terminal connected to the anode of the freewheeling diode D1 and a second terminal connected to ground.
The input capacitor C1 is used for stabilizing the input voltage VIN.
And the inductor L is used for storing electric energy.
And the freewheeling diode D1 is used for freewheeling when the electric energy stored in the inductor L is released to the output capacitor C2.
And a switching tube Q1 for receiving the PWM signal output by the controller 11 and turning on or off according to the PWM signal.
And the voltage sampling unit is used for sampling the output voltage VOUT and feeding back the sampled voltage to the feedback terminal FB of the controller 11, so that the controller 11 generates a PWM signal according to the sampled voltage.
Optionally, the voltage sampling unit includes: a first resistor R1 and a second resistor R2.
One end of the first resistor R1 is connected to the cathode of the freewheeling diode D1, the other end is connected to the feedback terminal FB of the controller 11 and one end of the second resistor R2, and the other end of the second resistor R2 is grounded.
In a specific implementation process, the controller 11 generates a PWM signal according to the sampled voltage of the output voltage VOUT sampled by the first resistor R1 and the second resistor R2, and controls the on and off of the switching tube Q1 through the PWM signal to obtain the output voltage VOUT higher than VIN, so as to supply power to the light emitting module. Specifically, assuming that the switching tube Q1 is turned off for a certain time, the voltage of the output capacitor C2 is equal to the input voltage VIN, and then the voltage is boosted through a charging phase and a discharging phase in sequence. During the charging phase, the switch Q1 is turned on, the input voltage VIN flows through the inductor L, and the freewheeling diode D1 prevents the capacitor from discharging to ground. Since the input voltage VIN is a dc voltage, the current on the inductor L linearly increases at a certain rate, and the inductor L stores energy as the current of the inductor L increases. In the discharging stage, the switching tube Q1 is turned off, and the current flowing through the inductor L does not suddenly disappear due to the current holding characteristic of the inductor L, but slowly gradually decreases from the highest value at the end of charging to 0. Since the switching tube Q1 is turned off, the inductor L can freewheel through the freewheeling diode D1, so that the inductor L starts to charge the output capacitor C2, the voltage across the output capacitor C2 rises, and the output voltage VOUT is higher than the input voltage VIN. The boosting effect is realized. The first string LEDs1 emit light under the action of the constant voltage provided by the regulator module 10, the sampling resistor R3 in the first current adjusting module 20 corresponding to the first string LEDs1 collects the first driving current of the first string LEDs1, the voltage regulator RG1 compares the collected first driving current with the reference signal, and the triode Q2 and the bias resistor R4 adjust the first driving current according to the comparison result, so that the first driving current and the reference signal tend to be consistent. The comparison result is sent to the controller 11 of the voltage stabilizing module 10 through the feedback resistor R5, so that the controller 11 generates a PWM signal according to the comparison result and the voltage feedback signal, and sends the PWM signal to the switching tube Q1, and a constant voltage is output through control and regulation of the switching tube Q1. Thereby providing a greater range of drive current adjustment for the LEDs1 of the first string of lights. Similarly, for other light strings, the driving currents of other light strings can be adjusted to be consistent with the reference signal through the current adjusting modules corresponding to the other light strings, so that the light emitting brightness of each light string is consistent, and the brightness uniformity of the backlight plate is improved.
The driving circuit provided by the embodiment is additionally provided with the current regulating module with simple structure and low cost on the basis of the boosting module in the constant-voltage mode with low cost, so that the currents of different lamp strings tend to be consistent, and the brightness uniformity of the backlight plate and the visual effect of the display screen are improved.
Fig. 8 is a circuit schematic diagram of a driving circuit according to another embodiment of the present invention, as shown in fig. 7, based on the embodiment shown in fig. 7, in this embodiment, a second light string LEDs2 and a corresponding second current adjusting module 30 are added, and in this embodiment, the driving circuit further includes: second string LEDs2 and second current regulation module 30.
The first end of the second string LEDs2 is connected to the output end of the voltage regulator module 10, and the other end is connected to the second current regulator module 30.
The second current adjusting module 30 is used for collecting the second driving current flowing through the second string LEDs2 and adjusting the second driving current according to the comparison result between the second driving current and the reference signal.
Optionally, as shown in fig. 8, the second current regulating module 30 includes a sampling resistor R6, a transistor Q3, a regulator tube RG2, a bias resistor R7, a feedback resistor R8, and a diode D3. The implementation principle of the second current regulation module 30 is similar to that of the second current regulation module 20.
In a specific implementation, the voltage regulator module 10 generates a constant voltage through voltage feedback, and supplies the constant voltage as a power voltage of the first string LEDs1 to the first string LEDs 1. The first string LEDs1 emit light under the action of a constant voltage, the first current adjusting module 20 corresponding to the first string LEDs1 collects the first driving current of the first string LEDs1, compares the collected first driving current with the reference signal, and adjusts the first driving current according to the comparison result, so that the first driving current and the reference signal tend to be consistent. The second string LEDs2 emit light under the action of a constant voltage, the second current adjusting module 30 corresponding to the second string LEDs2 collects the second driving current of the second string LEDs2, compares the collected second driving current with the reference signal, and adjusts the second driving current according to the comparison result, so that the second driving current and the reference signal tend to be consistent. Therefore, the brightness of each light string tends to be consistent, and the brightness uniformity of the backlight plate is further improved.
The driving circuit provided by the embodiment is additionally provided with the current regulating module with simple structure and low cost on the basis of the boosting module in the constant-voltage mode with low cost, so that the currents of different lamp strings tend to be consistent, and the brightness uniformity of the backlight plate and the visual effect of the display screen are improved.
An embodiment of the present invention further provides a driving method, which is applied to the driving circuits provided in the embodiments shown in fig. 2 and fig. 4 to fig. 8, and the method includes:
the voltage stabilizing module generates a constant voltage through voltage feedback, and the constant voltage is used as the power supply voltage of the first lamp string;
the first current adjusting module collects a first driving current flowing through the first lamp string and adjusts the first driving current according to a comparison result of the first driving current and the reference signal.
In this embodiment, the voltage stabilizing module may be a voltage boosting module or a voltage reducing module. The present embodiment is not limited to this, as long as a constant voltage can be supplied by voltage feedback adjustment.
In practical application, the driving circuit may include a plurality of light strings, and each light string is correspondingly provided with a current adjusting module, so that the working currents of the light strings tend to be consistent, and the brightness uniformity of the backlight plate is improved.
In a specific implementation, as shown in fig. 2, the voltage regulator module 10 generates a constant voltage through voltage feedback, and supplies the constant voltage as a power voltage of the first string LEDs1 to the first string LEDs 1. The first string LEDs1 emit light under the action of a constant voltage, the first current adjusting module 20 corresponding to the first string LEDs1 collects the first driving current of the first string LEDs1, compares the collected first driving current with the reference signal, and adjusts the first driving current according to the comparison result, so that the first driving current and the reference signal tend to be consistent. Similarly, for other light strings, the driving currents of other light strings can be adjusted to be consistent with the reference signal through the current adjusting modules corresponding to the other light strings, so that the light emitting brightness of each light string is consistent, and the brightness uniformity of the backlight plate is improved.
In the driving method provided by this embodiment, on the basis of the constant voltage mode, the current sampling resistor is connected in series to the lamp string to monitor the current, the monitored current is compared with the reference voltage of the voltage regulator tube, and the driving current flowing through the lamp string is adjusted according to the comparison result, so that the currents of different lamp strings tend to be consistent, and the brightness uniformity of the backlight plate and the visual effect of the display screen are improved.
In one particular embodiment, the first current regulation module includes: the current sampling circuit comprises a triode, a bias resistor, a current sampling resistor and a voltage stabilizing tube; the collector of the triode is connected with the second end of the first lamp string and is connected with the base through a bias resistor, and the emitter of the triode is connected with one end of a current sampling resistor and the voltage stabilizing end of a voltage stabilizing tube; the other end of the current sampling resistor is grounded; the cathode of the voltage-stabilizing tube is connected with the base electrode of the triode, and the anode of the voltage-stabilizing tube is grounded; the method further comprises the following steps:
the voltage stabilizing tube compares the first driving current sampled by the current sampling module with a reference signal and sends a comparison result to the triode;
the triode adjusts the first driving current according to the comparison result.
In a specific embodiment, the first current regulation module further comprises a feedback resistor, one end of the feedback resistor is connected with the cathode of the voltage regulator tube, and the other end of the feedback resistor is connected with the feedback end of the controller of the voltage regulator module; the method further comprises the following steps:
the controller generates a PWM signal according to a feedback signal of the feedback resistor;
the voltage stabilizing module generates an output voltage according to the PWM signal so as to regulate a first driving current flowing through the first lamp string.
The driving method provided by the embodiment of the invention is applied to the driving circuit embodiment, the implementation principle and the technical effect are similar, and the embodiment is not described herein again.
An embodiment of the present invention further provides a backlight panel, which includes the driving circuit of the above embodiment.
In the backlight provided by this embodiment, the driving circuit includes: a voltage stabilization module 10, a first string of lights LEDs1 and a first current regulation module 20; the output end of the voltage stabilizing module 10 is connected with the first end of the first string LEDs1, and the second end of the first string LEDs1 is connected with the first current adjusting module 20; the voltage stabilizing module 10 is used for generating a constant voltage through voltage feedback, and the constant voltage is used as a power supply voltage of the first string LEDs 1; the first current adjusting module 20 is configured to collect the first driving current flowing through the first string of LEDs1 and adjust the first driving current according to a comparison result between the first driving current and the reference signal. On the basis of a constant voltage mode, a current sampling resistor R3 is connected in series on the lamp string to monitor the current, the monitored current is compared with the reference voltage of a voltage regulator tube RG1, and the driving current flowing through the lamp string is regulated according to the comparison result, so that the currents of different lamp strings tend to be consistent, and the brightness uniformity of a backlight plate and the visual effect of a display screen are improved.
The invention further provides a display device, which comprises the backlight plate provided by the embodiment.
The driving circuit of the backlight plate in the display device provided by the embodiment comprises: a voltage stabilization module 10, a first string of lights LEDs1 and a first current regulation module 20; the output end of the voltage stabilizing module 10 is connected with the first end of the first string LEDs1, and the second end of the first string LEDs1 is connected with the first current adjusting module 20; the voltage stabilizing module 10 is used for generating a constant voltage through voltage feedback, and the constant voltage is used as a power supply voltage of the first string LEDs 1; the first current adjusting module 20 is configured to collect the first driving current flowing through the first string of LEDs1 and adjust the first driving current according to a comparison result between the first driving current and the reference signal. On the basis of a constant voltage mode, a current sampling resistor R3 is connected in series on the lamp string to monitor the current, the monitored current is compared with the reference voltage of a voltage regulator tube RG1, and the driving current flowing through the lamp string is regulated according to the comparison result, so that the currents of different lamp strings tend to be consistent, and the brightness uniformity of a backlight plate and the visual effect of a display screen are improved.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (13)
1. A driver circuit, comprising: the device comprises a voltage stabilizing module, a first lamp string and a first current regulating module;
the output end of the voltage stabilizing module is connected with the first end of the first lamp string, and the second end of the first lamp string is connected with the first current regulating module;
the voltage stabilizing module is used for generating a constant voltage through voltage feedback and taking the constant voltage as the power supply voltage of the first lamp string;
the first current adjusting module is used for collecting a first driving current flowing through the first lamp string and adjusting the first driving current according to a comparison result of the first driving current and a reference signal.
2. The driving circuit of claim 1, wherein the first current regulating module comprises: the current sampling circuit comprises a triode, a bias resistor, a current sampling resistor and a voltage stabilizing tube;
the collector of the triode is connected with the second end of the first lamp string and is connected with the base through the bias resistor, and the emitter of the triode is connected with one end of the current sampling resistor and the voltage stabilizing end of the voltage stabilizing tube; the other end of the current sampling resistor is grounded; the cathode of the voltage stabilizing tube is connected with the base electrode of the triode, and the anode of the voltage stabilizing tube is grounded;
the voltage regulator tube is used for comparing the first driving current sampled by the current sampling module with a reference signal and sending a comparison result to the triode;
and the triode is used for regulating the first driving current according to the comparison result.
3. The driver circuit of claim 2, wherein the current feedback module further comprises: an overvoltage protection module;
and one end of the overvoltage protection module is connected with the cathode of the voltage stabilizing tube, and the other end of the overvoltage protection module is grounded and is used for performing overvoltage protection on the voltage stabilizing tube.
4. The driving circuit of claim 3, wherein the overvoltage protection module comprises a first diode;
and the cathode of the first diode is connected with the cathode of the voltage stabilizing tube, and the anode of the first diode is grounded.
5. The driver circuit of claim 2, wherein the first current regulation module further comprises: a feedback resistor;
one end of the feedback resistor is connected with the cathode of the voltage stabilizing tube, and the other end of the feedback resistor is connected with the feedback end of the controller of the voltage stabilizing module;
the controller is used for generating a PWM signal according to a feedback signal of the feedback resistor;
the voltage stabilizing module is further configured to generate an output voltage according to the PWM signal to adjust a first driving current flowing through the first string of lights.
6. The drive circuit according to any one of claims 1 to 5, wherein the drive circuit further comprises: the second lamp string and the second current regulating module;
the first end of the second lamp string is connected with the output end of the voltage stabilizing module, and the other end of the second lamp string is connected with the second current regulating module;
the second current adjusting module is used for collecting a second driving current flowing through the second lamp string and adjusting the second driving current according to a comparison result of the second driving current and a reference signal.
7. The driving circuit according to any one of claims 1 to 4, wherein the voltage stabilizing module is a voltage boosting module or a voltage dropping module.
8. The driving circuit according to claim 7, wherein the voltage stabilizing module is a voltage boosting module, and the voltage stabilizing module comprises an input capacitor, an inductor, a freewheeling diode, an output capacitor, a switching tube, a controller and a voltage sampling unit;
one end of the inductor is connected with the input capacitor, and the other end of the inductor is connected with the first end of the switch tube and the anode of the freewheeling diode; the cathode of the freewheeling diode is connected with the output capacitor and the first end of the voltage sampling unit; the second end of the voltage sampling unit is grounded, and the output end of the voltage sampling unit is connected with the feedback end of the controller; the output end of the controller is connected with the control end of the switch tube; the first end of the switch tube is connected with the anode of the freewheeling diode, and the second end of the switch tube is grounded;
the input capacitor is used for stabilizing the input voltage;
the inductor is used for storing electric energy;
the freewheeling diode is used for freewheeling when the electric energy stored by the inductor is released to the output capacitor;
the switch tube is used for receiving the PWM signal output by the controller and conducting or disconnecting according to the PWM signal;
the voltage sampling unit is used for sampling the output voltage and feeding back the sampling voltage to the feedback end of the controller, so that the controller generates the PWM signal according to the sampling voltage.
9. A driving method applied to the driving circuit according to any one of claims 1 to 8, the method comprising:
the voltage stabilizing module generates a constant voltage through voltage feedback, and the constant voltage is used as the power supply voltage of the first lamp string;
the first current adjusting module collects a first driving current flowing through the first lamp string and adjusts the first driving current according to a comparison result of the first driving current and a reference signal.
10. The driving method according to claim 9, wherein the first current regulation module includes: the current sampling circuit comprises a triode, a bias resistor, a current sampling resistor and a voltage stabilizing tube; the collector of the triode is connected with the second end of the first lamp string and is connected with the base through the bias resistor, and the emitter of the triode is connected with one end of the current sampling resistor and the voltage stabilizing end of the voltage stabilizing tube; the other end of the current sampling resistor is grounded; the cathode of the voltage stabilizing tube is connected with the base electrode of the triode, and the anode of the voltage stabilizing tube is grounded; the method further comprises the following steps:
the voltage-stabilizing tube compares the first driving current sampled by the current sampling module with a reference signal and sends a comparison result to the triode;
and the triode regulates the first driving current according to the comparison result.
11. The driving method according to claim 10, wherein the first current regulation module further comprises a feedback resistor, one end of the feedback resistor is connected to the cathode of the regulator tube, and the other end of the feedback resistor is connected to the feedback end of the controller of the regulator module; the method further comprises the following steps:
the controller generates a PWM signal according to a feedback signal of the feedback resistor;
the voltage stabilizing module generates output voltage according to the PWM signal so as to regulate first driving current flowing through the first lamp string.
12. A backlight panel comprising the driving circuit according to any one of claims 1 to 8.
13. A display device comprising the backlight of claim 12.
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| CN202011282068.5A CN112382243A (en) | 2020-11-16 | 2020-11-16 | Driving circuit and method, backlight plate and display device |
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| CN202011282068.5A CN112382243A (en) | 2020-11-16 | 2020-11-16 | Driving circuit and method, backlight plate and display device |
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Application publication date: 20210219 |