CN113140190B - Backlight driving circuit, control method and display panel - Google Patents
Backlight driving circuit, control method and display panel Download PDFInfo
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- CN113140190B CN113140190B CN202110473004.1A CN202110473004A CN113140190B CN 113140190 B CN113140190 B CN 113140190B CN 202110473004 A CN202110473004 A CN 202110473004A CN 113140190 B CN113140190 B CN 113140190B
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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 application discloses drive circuit in a poor light for drive light emitting component, including adjusting module and drive module, adjusting module connects multiunit light emitting component and drive module, and drive module includes a plurality of drive transistor, and adjusting module is used for: obtaining the driving current of each group of light-emitting elements, comparing the driving currents to determine the maximum driving current, adjusting the gate voltage of each driving transistor according to the maximum driving current and adjusting the on-time of the driving transistor so that the current average value of the driving current is kept constant. In the application, thereby obtain light emitting component's drive current through regulating circuit and adjust drive transistor's voltage and on-time, guaranteed light emitting component's luminance homogeneity, simultaneously, can reduce drive transistor's consumption, saved the consumption, reduce drive transistor and damage the risk. In addition, the application also provides a display screen and a control method.
Description
Technical Field
The present application relates to the field of display technologies, and in particular, to a backlight driving circuit, a control method, and a display panel.
Background
With the continuous development of display technology, the size and resolution of the screen are continuously improved, and at present, the liquid crystal display screen can adopt a Mini-LED as a backlight module. However, the Mini-LED backlight module is composed of a plurality of rows of Mini-LED strings arranged in an array, and a plurality of backlight driving circuits are required to drive the corresponding Mini-LED strings, and the threshold voltage Vth of a part of metal-oxide semiconductor field effect transistors (MOSFET) in the backlight driving circuits may deviate from a standard value due to manufacturing difference between the backlight driving circuits, so that under the same gate voltage Vgs, the driving current Ids is not matched between different LED strings, which affects brightness uniformity.
Disclosure of Invention
The present application is directed to solving at least one of the problems in the prior art. Therefore, the present application needs to provide a backlight driving circuit, a control method and a display panel.
The backlight driving circuit is used for driving the light-emitting elements, and comprises an adjusting module and a driving module, wherein the adjusting module is connected with a plurality of groups of light-emitting elements and the driving module, the driving module comprises a plurality of driving transistors, one driving transistor is connected with a group of light-emitting elements, and the adjusting module is used for:
obtaining a driving current of each light emitting element;
comparing the drive currents to determine a maximum drive current; and
adjusting the gate voltage of each of the drive transistors according to the maximum drive current and adjusting the on-time of the drive transistors such that the current average of the drive currents remains constant.
In some embodiments, the adjusting module comprises a plurality of adjusting modules, each adjusting module comprises a control unit, a comparison unit and a pulse width modulation unit, the control unit is connected with a light emitting element, the pulse width modulation unit and the comparison unit, and the pulse width modulation unit is also connected with the grid electrode of the driving transistor;
the control unit is used for acquiring the driving current of the light-emitting element and generating a regulating voltage and a control signal according to the driving current;
the comparison unit is used for generating a driving voltage from a reference voltage according to the regulating voltage and transmitting the driving voltage to the pulse width modulation unit;
the pulse width modulation unit is used for transmitting the driving voltage to the grid electrode of the driving transistor according to the control signal.
In certain embodiments, the control unit comprises:
a current input terminal connected to the cathode of the light emitting element for transmitting a driving current of the light emitting element;
the voltage output unit is connected with the current input end and the comparison unit and used for generating the adjusting voltage according to the driving current of the light-emitting element and transmitting the adjusting voltage to the comparison unit;
and the control signal output unit is connected with the current input end and the pulse width modulation unit and is used for generating the control signal according to the driving current of the light-emitting element and transmitting the control signal to the pulse width modulation unit.
In some embodiments, the pulse width modulation unit comprises:
a first switch element, a first end of which is connected to the voltage output unit and the comparison unit, a second end of which is connected to the control signal output unit, and a third end of which is connected to the gate of the driving transistor;
and a first end of the second switching element is connected with the gate of the driving transistor, a second end of the second switching element is connected with the control signal output unit, and a third end of the second switching element is connected with a ground terminal.
In some embodiments, the comparison unit includes a voltage input unit, a first voltage comparator, and a second voltage comparator connected in sequence;
the first voltage comparator comprises a first positive input end, a first negative input end and a first output end, the first positive input end is connected with the voltage input unit, the first negative input end is connected with the source electrode of the driving transistor, and the first output end is connected with the second voltage comparator;
the second voltage comparator is connected with the voltage output unit and comprises a second positive input end, a second negative input end and a second output end, the second positive input end is connected with the first output end, and the second output end is connected with the pulse width modulation unit and the second negative input end.
In some embodiments, the voltage input unit includes an operational amplifier unit and an adjusting resistor, a first end of the operational amplifier unit is connected to the reference voltage input end, a second end of the operational amplifier unit is connected to the first positive input end, and the adjusting resistor is respectively connected to a ground end and a third end of the operational amplifier unit.
In some embodiments, the driving module further includes a power voltage input terminal and a feedback resistor, the power voltage input terminal is connected to the anode of the light emitting element, one end of the feedback resistor is connected to the source of the driving transistor, and the other end of the feedback resistor is connected to the ground.
In some embodiments, the driving transistor is an N-channel type metal-oxide-semiconductor field effect transistor.
The display panel of the embodiment of the present application includes a light emitting element and the backlight driving circuit of any one of the embodiments described above.
The driving control method according to the embodiment of the present application is applied to the backlight driving circuit described in any one of the above, and the driving control method includes:
acquiring a driving current in each of the light emitting elements;
comparing the drive currents to determine a maximum drive current;
adjusting the gate voltage of each of the drive transistors according to the maximum drive current and adjusting the on-time of the drive transistors such that the current average of the drive currents remains constant.
In the backlight driving circuit, the display screen and the control method in the embodiments of the present application, the driving current of each group of light emitting elements is obtained through the adjusting module, and the maximum driving current is obtained according to the comparison of the driving currents, so that the gate voltage of the driving transistor is adjusted, the driving current of each group of light emitting elements is equal to the maximum driving current, and meanwhile, the on-time of the driving transistor is controlled, so that the current average value of the driving current is kept constant. Therefore, the voltage division of the driving transistor is reduced while the brightness uniformity of the multiple groups of light-emitting elements is ensured, so that the power consumption of the driving transistor is reduced, and the risk of damage of the driving transistor is prevented.
Additional aspects and advantages of the present application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the present application.
Drawings
The above and/or additional aspects and advantages of the present application will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 is a schematic diagram of the principle characteristic of a driving transistor of the embodiment of the present application;
FIG. 2 is a block schematic diagram of a display screen according to an embodiment of the present application;
FIG. 3 is a schematic diagram of a connection module between a backlight driving circuit and a light emitting device according to an embodiment of the present disclosure;
fig. 4 is a circuit diagram of a backlight driving circuit according to an embodiment of the present application.
Description of the main element symbols:
the backlight driving circuit 10, the adjusting module 11, the comparing unit 111, the voltage input unit 1111, the operational amplifier 11111, the adjusting resistor R2, the first voltage comparator 1112, the second voltage comparator 1113, the control unit 112, the voltage output unit 1121, the control signal output unit 1122, the pulse width modulation unit 113, the first switching element 1131, and the second switching element 1132;
the driving module 12, the driving transistor 121, the power supply voltage input end PVDD, and the feedback resistor R1;
Detailed Description
Reference will now be made in detail to embodiments of the present application, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative and are only for the purpose of explaining the present application and are not to be construed as limiting the present application.
In the description of the present application, it is to be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the present application and for simplicity in description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed in a particular orientation, and be operated in a particular manner, and are not to be construed as limiting the present application. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.
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 the case may be.
In this application, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may comprise direct contact of the first and second features, or may comprise contact of the first and second features not directly but through another feature in between. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.
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. Further, the present application may repeat reference numerals and/or reference letters in the various examples for simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or arrangements 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.
With the continuous development of display technology, the size and resolution of the screen are continuously improved, and at present, the liquid crystal display screen can adopt a Mini-LED as a backlight module. The Mini-LED backlight module has the characteristic of high dynamic contrast, and the display of the liquid crystal display screen can be more prominent. However, the Mini-LED backlight module is composed of a plurality of rows of Mini-LED strings arranged in an array, and a plurality of backlight driving circuits are required to drive the corresponding Mini-LED strings, and the threshold voltage Vth of a part of metal-oxide semiconductor field effect transistors (MOSFET) in the backlight driving circuits may deviate from a standard value due to manufacturing difference between the backlight driving circuits, so that under the same gate voltage Vgs, the driving current Ids of different LED strings is not matched, which affects brightness uniformity.
In the related art, a feedback adjustment function may be provided inside a chip for driving a Mini-LED display, and the feedback adjustment function may adjust the gate voltage Vgs of the MOSFET deviating from a standard value so that the driving current Ids thereof is the same as the standard driving current of the standard Mini-LED string, for example, the threshold voltage Vgs of the MOSFET may be lowered on a large-current channel, and the driving current Ids may be reduced to lower the luminance of the corresponding Mini-LED, or the gate voltage Vgs may be increased on a small-current channel, and the driving current Ids may be further increased to raise the luminance of the corresponding Mini-LED until the driving current Ids is the same as the driving current Ids of the standard Mini-LED string. However, referring to FIG. 1, only a small portion of the voltage applied to the drain of the MOSFET itself is used as the pinch-off voltage of the MOSFET (the value is equal to the overdrive voltage: vgs-Vth), and the rest of the voltage is almost entirely applied to overcome the resistance of the pinch-off region to the drain current (excess voltage = Vds- (Vgs-Vth)), and the drive current Ids will not change regardless of the increase of the drive voltage Vds. After the gate voltage Vgs of the LED string with large current is reduced, the driving current Ids is reduced, the voltage drop of the LED string can be reduced, the power supply voltage (fixed value) output by the power supply end Vboost acts on a MOSFET (metal-oxide-semiconductor field effect transistor), and due to the reduction of the gate driving voltage Vgs, the pinch-off voltage can be reduced, so that more redundant energy acting on the MOSFET is consumed on the MOSFET, the MOSFET is heated, the power consumption is greatly wasted, and the risk of burning the MOSFET is increased.
Referring to fig. 2, in view of the above, the present application provides a display panel 100, where the display panel 100 includes a backlight driving circuit 10, a backlight module 20 and a display panel 30. The display panel 30 is disposed corresponding to the backlight module 20, and the backlight driving circuit 10 is connected to the backlight module 20 and is configured to drive the backlight module 20 to emit light.
The display screen 100 can be applied to smart wearable devices such as televisions, computers, mobile phones, tablet or electronic watches, VR devices, AR devices, and the like. For example, in some examples, display screen 100 may be implemented on a television, and display screen 100 refers to a television screen.
The Display 100 is a Liquid Crystal Display (LCD). The display panel 30 is used for displaying an image to be displayed, and the backlight module 20 is used for generating backlight to cooperate with the display panel 30 to display the image to be displayed.
The display panel 30 may be divided into a plurality of display regions, and the number of the display regions may be 4, 6, 8 or even more, and the specific number of the display regions is not limited. Each display area comprises a plurality of pixel units, and the display area displays an image to be displayed through the pixel units.
The backlight module 20 may include a plurality of light emitting elements 22 arranged in an array, and the plurality of light emitting elements 22 arranged in an array are divided into a plurality of groups, each group of light emitting elements 22 may include one or more light emitting elements, and it is understood that the cathode terminal of each group of light emitting elements 22 is the cathode of the last light emitting element 22 along the current direction. The light emitting elements 22 may be OLEDs, mini-LEDs, micro-LEDs, or the like, for example, the Mini-LEDs may be used as the light emitting elements 22 in the present application, that is, the backlight module 20 is formed by arranging a plurality of Mini-LEDs in an array.
Referring to fig. 3, the backlight driving circuit 10 is used for driving the light emitting element 22 to emit light, and the backlight driving circuit 10 includes a regulating module 11 and a driving module 12. The driving module 12 is connected with the adjusting module 11 and the plurality of groups of light emitting elements 22, the adjusting module 11 is respectively connected with the light emitting elements 22 and the driving module 12, the driving module 12 includes a plurality of driving transistors 121, the driving transistors 121 are connected with the light emitting elements 22, and the adjusting module 11 is used for: the driving currents of each group of light emitting elements 22 are acquired and compared to determine the maximum driving current, and the gate voltage of each driving transistor 121 is adjusted according to the maximum driving current and the on-time of the driving transistor 121 is adjusted so that the pwm signal of the driving transistor 121 is equal to the preset pwm signal.
In the display screen 100 and the backlight driving circuit 10 of the present application, the driving current provided to the light emitting elements 22 in each driving transistor 121 is obtained through the adjusting module 11, and the maximum driving current is obtained through comparison, and then the gate voltage of the driving transistor 121 is adjusted by using the maximum driving current as a standard, so that the driving current of each group of light emitting elements 22 is equal to the maximum driving current by the driving transistor 121 according to the gate voltage, and meanwhile, the on-time of the driving transistor 121 is also controlled, so that the current average value of the driving current is kept constant. Thus, the luminance uniformity of the light emitting element 22 is ensured, the voltage dividing effect of each driving transistor 121 can be reduced, the consumption of redundant energy on the driving transistor 121 is avoided, the power consumption is reduced, and the risk of burning out the driving transistor 121 is reduced.
In the embodiment of the present application, the driving transistor 121 may be a metal-oxide semiconductor field effect transistor or other switching devices with the same characteristics. The source and drain of the transistor used herein may be symmetrical in structure, so that there may be no difference in structure between the source and drain.
In addition, the transistors may be classified into N-type and P-type transistors according to their characteristics, the embodiments of the present disclosure are each explained by taking an N-type transistor as an example, and the driving transistor 121 is an N-channel type metal-oxide-semiconductor field effect transistor. That is, in the embodiment of the present application, when the gate of the driving transistor 121 receives a high level signal, the source and the drain of the driving transistor 121 are turned on. Based on the description and teaching of the present disclosure for the N-type transistor implementation, a person of ordinary skill in the art can easily conceive of the implementation of the present disclosure using the P-type transistor without any creative effort, and therefore, these implementations are also within the protection scope of the present disclosure.
The current average value is a product of the magnitude of the drive current and the duty ratio of the drive current, and the luminance of the light-emitting element can be kept stable by keeping the current average value of the drive current constant, and the luminance of the light-emitting element can be kept stable as the product of the magnitude of the drive current and the duty ratio of the drive current is more stable. The duty cycle of the drive current refers to the duty cycle of the pulse modulated signal (PWN) for the duration of the drive current.
Pulse Width Modulation (PWM) is an analog control method, and modulates the bias of the base of a transistor or the gate of an MOS transistor according to the change of a corresponding load to change the conduction time of the transistor or the MOS transistor, thereby changing the output of a switching regulator.
It will be appreciated that since the duration of the drive current is equal to the on-time of the drive transistor, that is, the duty cycle of the drive current can be controlled by controlling the on-time of the drive transistor. And the driving transistor is an N-channel metal-oxide-semiconductor field effect transistor and is conducted when the grid voltage of the driving transistor is high level voltage.
Referring to fig. 4, in particular, the driving module 12 includes a power voltage input terminal PVDD, a driving transistor 121, and a feedback resistor R1, wherein the power voltage input terminal PVDD is connected to an anode of the light emitting element 22 and is used for transmitting a power voltage to the light emitting element 22, and the magnitude of the power voltage is constant. The drain of the driving transistor 121 is connected to the cathode of the light emitting element 22. The source of the driving transistor 121 is connected to one end of the feedback resistor R1, and the other end of the feedback resistor R1 is grounded. One end of the adjustment module 11 is connected to the gate of the driving transistor 121, and the other end is connected to the cathode of the light emitting element 22.
It can be understood that the calculation formula of the driving current Ids is:
Ids＝(1/2)UnCox(W/L)*(Vgs-Vth) 2
in the formula: un: is the rate of migration of electrons. And (3) Cox: is the unit area gate oxide capacitance. W/L: width-to-length ratio of oxide layer. Vgs-Vth: is the overdrive voltage.
Since the driving transistor 121 is an N-channel type metal-oxide-semiconductor field effect transistor, when the gate voltage of the driving transistor 121 reaches the turn-on voltage of the driving transistor 121 and continues to increase, the turn-on degree of the driving transistor 121 increases, so that the driving current of the light emitting element 22 increases. The voltage across the light emitting element 22 is related to the driving current flowing through the light emitting element 22, and the power supply voltage inputted from the power supply voltage input terminal PVDD is a constant value. Therefore, the adjusting module 11 can obtain the driving current flowing through the light emitting element 22, generate the on-time of the adjusting driving transistor 121 according to the driving current, and adjust the voltage of the gate of the driving transistor 121 to realize the adjustment of the driving current of the light emitting element 22. Thereby, the drive current flowing through the light emitting element 22 is increased so that the voltage Vds across the drain and source of the drive transistor 121 is reduced, thereby reducing the consumption of energy on the drive transistor 121, and thus reducing the power consumption, and reducing the risk of burning out the drive transistor 121.
The adjusting module 11 includes a plurality of adjusting modules 11, and the plurality of adjusting modules 11 may be connected such that each adjusting module can obtain the magnitude of each set of driving current. Each adjusting module 11 comprises a control unit 112, a comparing unit 111 and a pulse width modulation unit 113. The control unit 11 is configured to obtain a driving current flowing through the light emitting element 22, compare the driving current with a maximum driving current, compare the maximum driving current with the driving current flowing through the current light emitting element 22 to generate an adjustment voltage and a control signal, transmit the adjustment voltage to the comparison unit 112, and transmit the control signal to the pulse width modulation unit 113.
Further, the control unit 112 includes a current input terminal, a voltage output unit 1121 and a control signal output unit 1122, wherein the current input terminal is connected to the cathode of the light emitting element 22 and is used for obtaining the driving current of the light emitting element 22, and the voltage output unit 1121 is connected to the current input terminal and the comparison unit 111 and is used for generating the adjustment voltage according to the driving current of the light emitting element 22 and transmitting the adjustment voltage to the comparison unit 112. The control signal output unit 1122 is connected to the current input terminal and the pulse width modulation unit 113, and is configured to generate a control signal according to the driving current of the light emitting element 22 and transmit the control signal to the pulse width modulation unit 113.
The pwm unit 113 is further connected to the comparison unit 111 and the gate of the driving transistor 121, the comparison unit 111 is configured to generate a driving voltage according to the adjustment voltage and transmit the driving voltage to the pwm unit 113, and the pwm unit 113 is configured to generate a pwm signal according to the control signal and the driving voltage and transmit the pwm signal to the gate of the driving transistor 121 to control the conduction degree and the conduction time of the driving transistor 121, so that the driving current flowing through the light emitting element 22 is the maximum driving current, and at the same time, the product of the duration of the driving current and the magnitude of the driving current is kept constant.
Further, the pulse width modulation unit 113 includes a first switching element 1131 and a second switching element 1132, a first end of the first switching element 1131 is connected to the comparing unit 111 for receiving the driving voltage output by the comparing unit 111, and a second end of the first switching element 1131 is connected to the control signal output unit 1122 for receiving the control signal transmitted by the control signal output unit 1122. The third terminal of the first switch element 1131 is connected to the gate of the driving transistor 121, when the first switch element 1131 receives a control signal, the first switch element 1131 is closed, the comparing unit 111 is connected to the gate of the driving transistor 121, the comparing unit 111 writes a driving voltage into the gate of the driving transistor 121, the driving voltage is a high-level signal, the driving transistor 121 is turned on, and the light emitting element 22 emits light. A first terminal of the second switching element 1132 is connected to the gate of the driving transistor 121, a second terminal of the second switching element 1132 is connected to the control signal output unit 1122, and a third terminal of the second switching element 1132 is connected to the ground terminal. After the second switching element 1132 receives the control signal, the second switching element 1132 is closed, the gate of the driving transistor 121 is connected to the ground terminal, a low level signal is written into the gate of the driving transistor 121, and the driving transistor 121 is turned off.
In some embodiments, the comparison unit 111 includes a voltage input unit 1111, a first voltage comparator 1112, and a second voltage comparator 1113, which are connected in sequence.
The first voltage comparator 1112 includes a first positive input terminal, a first negative input terminal, and a first output terminal. The first positive input terminal is connected to the voltage input unit 1111, the first negative input terminal is connected to the source of the driving transistor 121, and the first output terminal is connected to the second voltage comparator 1113.
The second voltage comparator 1113 is also connected to the voltage output unit 1121 and the pulse width modulation unit 113. Specifically, the second voltage comparator includes a second positive input terminal, a second negative input terminal, and a second output terminal, where the second positive input terminal is connected to the first output terminal, and the second output terminal is connected to the first switching element 1131 and the second negative input terminal, and is configured to generate a driving voltage from the reference voltage according to the regulated voltage of the voltage output unit 1121, and transmit the driving voltage to the first switching element 1131.
In some embodiments, the voltage input unit 1111 is configured to transmit a reference voltage to the first voltage comparator 1112. Specifically, the voltage input unit 1111 includes an operational amplifier unit 11111 and an adjusting resistor R2, a first terminal of the operational amplifier unit 11111 is connected to the reference voltage input terminal Vref, a second terminal of the operational amplifier unit 11111 is connected to the first positive input terminal of the first voltage comparator 1112, and the adjusting resistor R2 is respectively connected to the ground terminal and the third terminal of the operational amplifier unit 11111.
The process of the backlight driving circuit 10 will be briefly described. The power supply voltage input terminal PVDD is used to supply a power supply voltage to the light emitting element 22 to cause the light emitting element 22 to emit light. The current input terminal of the control unit 112 obtains the current driving current flowing through the light emitting elements 22, compares the driving current with the light emitting elements 22 of other groups to obtain the maximum driving current, generates an adjustment voltage according to the driving current and the maximum driving current through the voltage output unit 1121, and transmits the adjustment voltage to the second voltage comparator 1113, and generates a control signal according to the current driving current and the maximum driving current through the control signal output unit 1122, and transmits the control signal to the pulse width modulation unit 113. The second voltage comparator 1113 generates a driving voltage after receiving the adjustment voltage and transmits the driving voltage to the first switching element 1131 of the pulse width modulation unit 113, the first switching element 1131 of the pulse width modulation unit 113 is closed after receiving the control signal, transmits the driving voltage to the driving transistor 121, and the driving transistor 121 adjusts the driving current to the maximum driving current according to the driving voltage. The second switching element 1132 is closed after receiving the control signal. The low level signal of the ground terminal is transmitted to the gate of the driving transistor 121, so that the driving transistor 121 is turned off. Thus, the average value of the current of the drive current flowing through the light emitting element 22 is kept constant.
The embodiment of the present application further provides a driving control method, which is used for the backlight driving circuit 10 of any one of the above embodiments, and the driving control method includes:
012: acquiring a driving current of a light emitting element;
014: comparing the drive currents to determine a maximum drive current;
016: the gate voltage of each drive transistor is adjusted in accordance with the maximum drive current shown and the on-time of the drive transistor is adjusted so that the current average value of the drive current remains constant.
In this way, the driving current provided by the driving transistor to the light emitting elements 22 is obtained, the maximum driving current is obtained through comparison, and then the gate voltage of the driving transistor is adjusted by taking the maximum driving current as a standard, so that the driving current of each group of light emitting elements 22 is equal to the maximum driving current, and meanwhile, the on-time of the driving transistor is also controlled, so that the current average value of the driving current of the driving transistor 121 is kept constant, thus, the brightness uniformity of the light emitting elements 22 is ensured, meanwhile, the energy consumption of each driving transistor can be reduced, and the power consumption of the display screen is reduced.
In the description herein, references to the description of the terms "one embodiment," "certain embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that: numerous changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the application, the scope of which is defined by the claims and their equivalents.
Claims (9)
1. A backlight driving circuit for driving light emitting elements, comprising an adjusting module and a driving module, wherein the adjusting module is connected to a plurality of sets of the light emitting elements and the driving module, the driving module comprises a plurality of driving transistors, the driving transistors are connected to a set of the light emitting elements, and the adjusting module is configured to:
obtaining a driving current of each group of the light-emitting elements;
comparing the drive currents to determine a maximum drive current; and
adjusting the gate voltage of each driving transistor according to the maximum driving current and adjusting the on-time of the driving transistor to keep the current average value of the driving current constant;
the adjusting modules comprise a plurality of adjusting modules, each adjusting module comprises a control unit, a comparison unit and a pulse width modulation unit, the control unit is connected with the light-emitting element, the pulse width modulation unit and the comparison unit, and the pulse width modulation unit is also connected with the grid electrode of the driving transistor;
the control unit is used for acquiring the driving current of the light-emitting element and generating a regulating voltage and a control signal according to the driving current;
the comparison unit is used for generating a driving voltage from a reference voltage according to the regulating voltage and transmitting the driving voltage to the pulse width modulation unit;
the pulse width modulation unit is used for transmitting the driving voltage to the grid electrode of the driving transistor according to the control signal.
2. The backlight driving circuit according to claim 1, wherein the control unit comprises:
a current input terminal connected to the cathode of the light emitting element for transmitting a driving current of the light emitting element;
the voltage output unit is connected with the current input end and the comparison unit and used for generating the adjusting voltage according to the driving current of the light-emitting element and transmitting the adjusting voltage to the comparison unit;
and the control signal output unit is connected with the current input end and the pulse width modulation unit and is used for generating the control signal according to the driving current of the light-emitting element and transmitting the control signal to the pulse width modulation unit.
3. The backlight driving circuit according to claim 2, wherein the pulse width modulation unit comprises:
a first switch element, a first end of which is connected to the voltage output unit and the comparison unit, a second end of which is connected to the control signal output unit, and a third end of which is connected to the gate of the driving transistor;
and a first end of the second switching element is connected with the gate of the driving transistor, a second end of the second switching element is connected with the control signal output unit, and a third end of the second switching element is connected with a ground terminal.
4. The backlight driving circuit according to claim 3, wherein the comparing unit includes a voltage input unit, a first voltage comparator and a second voltage comparator connected in sequence;
the first voltage comparator comprises a first positive input end, a first negative input end and a first output end, the first positive input end is connected with the voltage input unit, the first negative input end is connected with the source electrode of the driving transistor, and the first output end is connected with the second voltage comparator;
the second voltage comparator is connected with the voltage output unit and the pulse width modulation unit, the second voltage comparator comprises a second positive input end, a second negative input end and a second output end, the second positive input end is connected with the first output end, and the second output end is connected with the pulse width modulation unit and the second negative input end.
5. The backlight driving circuit according to claim 4, wherein the voltage input unit comprises an operational amplifier unit and an adjusting resistor, a first terminal of the operational amplifier unit is connected to a reference voltage input terminal, a second terminal of the operational amplifier unit is connected to the first positive input terminal, and the adjusting resistor is respectively connected to a ground terminal and a third terminal of the operational amplifier unit.
6. The backlight driving circuit according to claim 1, wherein the driving module further comprises a power voltage input terminal and a feedback resistor, the power voltage input terminal is connected to the anode of the light emitting element, one end of the feedback resistor is connected to the source of the driving transistor, and the other end is connected to a ground terminal.
7. The backlight driving circuit according to claim 1, wherein the driving transistor is an N-channel type metal-oxide-semiconductor field effect transistor.
8. A display panel comprising light emitting elements and the backlight driving circuit according to any one of claims 1 to 7.
9. A control method for a backlight driving circuit according to any of claims 1-7, the control method comprising:
acquiring a driving current in each of the light emitting elements;
comparing the drive currents to determine a maximum drive current;
adjusting the gate voltage of each of the drive transistors according to the maximum drive current and adjusting the on-time of the drive transistors such that the current average of the drive currents remains constant.
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| CN116741107A (en) * | 2022-03-04 | 2023-09-12 | 华为技术有限公司 | Backlight driving circuit, chip, backlight module and electronic equipment |
| CN114863870B (en) * | 2022-05-10 | 2023-05-26 | 绵阳惠科光电科技有限公司 | Drive control circuit and display device |
| CN115132130A (en) * | 2022-07-18 | 2022-09-30 | 苏州华星光电技术有限公司 | Backlight module and display device |
| WO2024021080A1 (en) * | 2022-07-29 | 2024-02-01 | 京东方科技集团股份有限公司 | Driving circuit, backlight module and driving method therefor, and display apparatus |
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