CN110010085B - Backlight driving adjusting circuit, chip and method - Google Patents
Backlight driving adjusting circuit, chip and method Download PDFInfo
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- CN110010085B CN110010085B CN201910245625.7A CN201910245625A CN110010085B CN 110010085 B CN110010085 B CN 110010085B CN 201910245625 A CN201910245625 A CN 201910245625A CN 110010085 B CN110010085 B CN 110010085B
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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
Abstract
The invention discloses a backlight driving and adjusting circuit, a chip and a method, wherein the backlight driving and adjusting circuit comprises: the backlight control unit is used for driving and controlling the backlight module; a segment dimming voltage setting unit for setting a segment dimming voltage; the dimming control unit is used for carrying out dimming algorithm control on the dimming pulse signal; the segmented voltage setting unit is connected with the dimming control unit, and the dimming control unit is connected with the backlight control unit. The invention realizes the mixed dimming function through the backlight driving and adjusting circuit, the chip and the method, solves the noise problem of dimming inductance in a single PWM dimming mode, eliminates the problem of rolling interference of pictures caused by beat interference, and effectively improves the picture quality and the display effect of televisions and other display equipment.
Description
Technical Field
The invention relates to the technical field of backlight drive control, in particular to a backlight drive adjusting circuit, a backlight drive adjusting chip and a backlight drive adjusting method.
Background
At present, in LED televisions and other liquid crystal display devices, a backlight module driving chip mainly adopts two dimming modes, i.e., an analog dimming mode and a PWM (Pulse Width Modulation) dimming mode.
For the analog dimming mode, the voltage range controlled by the analog dimming mode is generally smaller, so that the current regulation range of the lamp strip controlled by the analog dimming mode is smaller. Along with the continuous increase of lamp strip electric current among the practical application, backlight unit is when the simulation is adjusted luminance and is reached minimum level, and the lamp strip still keeps great electric current, and luminance in a poor light is still higher, hardly satisfies the module and controls by bright to dark full range. Meanwhile, if the range of the analog dimming level is widened, the difference between the color temperature of the lamp strip when the backlight module is dark and the brightness of the backlight module is high is large, which is not beneficial to the consistency debugging of image quality, and therefore, the analog dimming level cannot be popularized and applied comprehensively in large-size display equipment.
PWM dimming is a commonly used dimming method at present, and is widely applied to the field of LED televisions and other large-sized display devices. During module brightness control, through adjusting PWM duty cycle, backlight unit can realize better linear brightness control by dark to bright control's the whole range. However, PWM dimming has the following problems:
firstly, the lighting effect of the lamp strip in the PWM dimming mode is low;
secondly, the PWM dimming has the noise problem of a dimming inductor, and compared with a simulation dimming mode, the constant current inductor has higher noise;
third, the problem of beat interference between the PWM dimming frequency and the field frequency of the LED glass causes the picture to have rolling interference, which is difficult to eliminate.
Thus, the prior art has yet to be improved and enhanced.
Disclosure of Invention
In view of the foregoing disadvantages of the prior art, an object of the present invention is to provide a backlight driving and adjusting circuit, a chip and a method, which can achieve a hybrid dimming function and improve the image quality and display effect of a display device such as a television.
In order to achieve the purpose, the invention adopts the following technical scheme:
a backlight driving adjustment circuit, comprising:
backlight control unit for driving and controlling backlight module
A segment dimming voltage setting unit for setting a segment dimming voltage;
the dimming control unit is used for carrying out dimming algorithm control on the dimming pulse signal;
the segmented dimming voltage setting unit is connected with the dimming control unit, and the dimming control unit is connected with the backlight control unit.
In the backlight driving and adjusting circuit, the backlight driving and adjusting circuit further comprises a voltage dividing unit, the voltage dividing unit comprises a first resistor and a second resistor, one end of the first resistor is used for inputting a reference voltage, and the other end of the first resistor is respectively connected with one end of the second resistor and the segmented dimming voltage setting unit.
The backlight driving and adjusting circuit is characterized by further comprising a boosting power unit, wherein the boosting power unit comprises a boosting inductor, a boosting MOS (metal oxide semiconductor) tube, a first diode, an output capacitor, a third resistor and a fourth resistor, VIN (voltage-in-voltage) is input into one end of the boosting inductor, the other end of the boosting inductor is respectively connected with a drain electrode of the boosting MOS tube and an anode of the first diode, one end of the output capacitor is connected with a cathode of the first diode and outputs backlight voltage to the backlight module, the other end of the output capacitor is grounded, a grid electrode of the boosting MOS tube is connected with the backlight control unit, a source electrode of the boosting MOS tube is connected with one end of the third resistor and one end of the fourth resistor, the other end of the third resistor is grounded, and the other end of the fourth resistor is connected with the backlight control unit.
In the backlight driving and adjusting circuit, the backlight driving and adjusting circuit further comprises a backlight adjusting unit, the backlight adjusting unit comprises a dimming MOS tube and a fifth resistor, a grid electrode of the dimming MOS tube is connected with the backlight control unit, a source electrode of the dimming MOS tube is connected with one end of the backlight control unit and one end of the fifth resistor, the other end of the fifth resistor is grounded, and a drain electrode of the dimming MOS tube is connected with the backlight module.
A backlight driving and adjusting chip comprises a chip body, wherein the chip body is integrated with a backlight driving and adjusting circuit.
A backlight driving adjustment method, comprising the steps of:
setting a value of the segment dimming voltage;
receiving a dimming pulse signal sent by a main board and obtaining the duty ratio of the dimming pulse signal;
and selecting a dimming mode of the backlight module according to the value of the segmented dimming voltage and the duty ratio of the dimming pulse signal, and adjusting and driving the backlight module.
In the backlight driving and adjusting method, the step of setting the segment dimming voltage specifically includes:
acquiring a fixed reference voltage;
and dividing the reference voltage to obtain a segmented dimming voltage, and controlling the segmented dimming voltage by a comparator array and an algorithm to obtain different dimming intervals.
In the backlight driving and adjusting method, the step of selecting the dimming mode of the backlight module according to the value of the segmented dimming voltage and the duty ratio of the dimming pulse signal, and the step of adjusting and driving the backlight module specifically includes:
when the segmented dimming voltage is less than a volt, if the duty ratio of the dimming pulse signal is less than A%, the dimming mode is a PWM dimming mode; if the duty ratio of the dimming pulse signal is more than A%, the dimming mode is an analog dimming mode;
when the segmented dimming voltage is larger than a volt and smaller than B volt, if the duty ratio of the dimming pulse signal is smaller than B%, the dimming mode is a PWM dimming mode; if the duty ratio of the dimming pulse signal is greater than B%, the dimming mode is an analog dimming mode;
when the segmented dimming voltage is greater than b volt and less than C volt, if the duty ratio of the dimming pulse signal is less than C%, the dimming mode is a PWM dimming mode; if the duty ratio of the dimming pulse signal is larger than C%, the dimming mode is an analog dimming mode;
when the segmented dimming voltage is larger than c volts, if the duty ratio of the dimming pulse signal is smaller than D%, the dimming mode is a PWM dimming mode; if the duty ratio of the dimming pulse signal is larger than D%, the dimming mode is an analog dimming mode;
after the dimming mode of the backlight module is selected, the backlight module is adjusted and driven;
wherein 0< a < B < C < D <100,0< a < B < C.
In the backlight driving and adjusting method, the step of receiving the dimming pulse signal sent by the main board and obtaining the duty ratio of the dimming pulse signal specifically includes:
receiving a dimming pulse signal sent by a main board;
and performing direct current conversion on the dimming pulse signal to obtain direct current conversion voltage corresponding to the duty ratio of the dimming pulse signal.
In the backlight driving and adjusting method, the step of performing dc conversion on the dimming pulse signal to obtain a dc conversion voltage corresponding to the duty ratio of the dimming pulse signal specifically includes:
when the duty ratio of the pulse dimming signal is 100%, the corresponding direct current conversion voltage is a 1;
when the duty ratio of the pulse dimming signal is 50%, the corresponding direct current conversion voltage is 0.5a 1;
when the duty ratio of the pulse dimming signal is D%, the corresponding direct current conversion voltage is a 2;
when the duty ratio of the pulse dimming signal is C%, the corresponding direct current conversion voltage is a 3;
when the duty ratio of the pulse dimming signal is B%, the corresponding direct current conversion voltage is a 4;
when the duty ratio of the pulse dimming signal is A%, the corresponding direct current conversion voltage is a 5;
when the duty ratio of the pulse dimming signal is 0%, the corresponding direct current conversion voltage is 0;
wherein 0< a < B < C < D <100,0< a5< a4< a3< a2< a 1.
Compared with the prior art, the backlight driving and adjusting circuit, the chip and the method provided by the invention have the advantages that: the backlight control unit is used for driving and controlling the backlight module; a segment dimming voltage setting unit for setting a segment dimming voltage; the dimming control unit is used for carrying out dimming algorithm control on the dimming pulse signal; the segmented dimming voltage setting unit is connected with the dimming control unit, and the dimming control unit is connected with the backlight control unit. The invention realizes the mixed dimming function through the backlight driving and adjusting circuit, the chip and the method, solves the noise problem of dimming inductance in a single PWM dimming mode, eliminates the problem of rolling interference of pictures caused by beat interference, and effectively improves the picture quality and the display effect of televisions and other display equipment.
Drawings
Fig. 1 is a schematic circuit diagram of a backlight driving adjusting circuit according to the present invention.
Fig. 2 is a flowchart of a backlight driving adjusting method according to the present invention.
Fig. 3 is a flowchart of step S100 in a backlight driving adjustment method according to the present invention.
Fig. 4 is a flowchart of step S200 in a backlight driving adjustment method according to the present invention.
Fig. 5 is a flowchart of step S220 in a backlight driving adjustment method according to the present invention.
Fig. 6 is a flowchart of step S300 in a backlight driving adjustment method according to the present invention.
Detailed Description
The present invention provides a backlight driving and adjusting circuit, a chip and a method thereof, and in order to make the objects, technical solutions and effects of the present invention clearer and clearer, the present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Referring to fig. 1, a schematic circuit diagram of a backlight driving and adjusting circuit provided by the present invention is shown, and the present invention also provides a backlight driving and adjusting chip, where the backlight driving and adjusting chip includes a chip body 100, the backlight driving and adjusting circuit is wholly or partially integrated on the chip body 100, and the backlight driving and adjusting circuit includes:
a backlight control unit 10 for driving and controlling the backlight module;
a segment dimming voltage setting unit 20 for setting a segment dimming voltage;
a dimming control unit 30 for performing dimming algorithm control on the dimming pulse signal;
the segmented dimming voltage setting unit is connected with the dimming control unit 30, the dimming control unit 30 is connected with the backlight control unit 10, and the backlight control unit 10 is connected with the backlight module 40.
The backlight driving adjusting chip is based on a backlight constant current control chip kernel, a segmented dimming voltage setting unit 20 and a dimming control unit 30 are added on the basis of an original backlight control unit 10, and a dimming chip design scheme capable of setting a simulated dimming and PWM dimming proportion is formed, namely, a PWM dimming mode of the original chip is changed into a CPWM (hybrid dimming function) dimming mode.
The chip body 100 is provided with a CPWM pin, and a dimming pulse signal sent by the mainboard can be sent into the chip body 100 through the defined CPWM pin. Meanwhile, the chip body 100 is further provided with an ADIM pin and a VREF pin, and a voltage dividing unit 50 is disposed on the periphery of the chip body 100 (or may be integrated on the chip body 100), where the voltage dividing unit 50 is configured to divide a reference voltage on the VREF pin and send the divided reference voltage to the ADIM pin.
In a specific embodiment, the voltage dividing unit 50 includes a first resistor R1 and a second resistor R2, one end of the first resistor R1 is connected to the VREF pin, the other end of the first resistor R1 is connected to one end of the second resistor R2 and the ADIM pin, respectively, and the other end of the second resistor R2 is grounded.
The VREF voltage on the VREF pin is a fixed reference voltage inside the backlight driving adjustment chip, and the ADIM voltage on the ADIM pin is obtained by passing the VREF voltage inside the chip body 100 through the voltage division unit 50. The step dimming voltage setting unit 20 includes a comparator array (in this embodiment, the comparator array includes a first comparator U1, a second comparator U2, and a third comparator U3) formed by a plurality of comparators, and the ADIM voltage passes through the comparator array inside the step dimming voltage setting unit 20 (the input ADIM voltage signal is compared with a series of reference voltages) and is subjected to algorithm control by the dimming control unit 30, so that different dimming levels can be obtained, and the control thresholds correspond to different duty ratios of the externally input CPWM signal.
In a further embodiment, the chip body 100 is further provided with a DRI pin and an ISW pin respectively connected to the backlight control unit 10 in the dimming control circuit, a boost power unit 60 is disposed at the periphery of the chip body 100, and the boost power unit 60 is connected to the backlight module 40 (in this embodiment, the backlight module 40 is composed of an LED backlight bar) and provides a backlight voltage for the backlight module 40.
Specifically, the boost power unit 60 includes a boost inductor L1, a boost MOS transistor Q1, a first diode D1, an output capacitor C2, a third resistor R3, and a fourth resistor R4, wherein a VIN voltage of the motherboard is input to one end of the boost inductor L1, the other end of the boost inductor L1 is respectively connected to a drain of the boost MOS transistor Q1 and an anode of the first diode D1, a cathode of the first diode D1 is connected to one end of the output capacitor C2 and the backlight module, the other end of the output capacitor C2 is grounded, a gate of the boost MOS transistor Q1 is connected to a DRI pin of the chip body 100, a source of the boost MOS transistor Q1 is connected to one end of the third resistor R3 and one end of the fourth resistor R4, the other end of the third resistor R3 is grounded, and the other end of the fourth resistor R4 is connected to an ISW end of the chip body 100.
The DRI pin is a driving pin of the boost MOS transistor Q1, the ISW pin is a power loop current detection pin, and the chip body 100 controls the boost MOS transistor Q1 to be turned on and off through the DRI pin, so as to control the boost power unit 60 to work, and boost the input VIN voltage to the backlight voltage required by the backlight module. The ISW pin is a power loop current detection pin, and the third resistor R3 and the fourth resistor R4 are current sampling resistors.
Meanwhile, an ADRI pin and an ISEN pin are further arranged on the chip body 100, a backlight adjusting unit 70 is further arranged on the periphery of the chip body 100, and the backlight adjusting unit 70 comprises a dimming MOS transistor Q2 and a fifth resistor R5. The ADRI pin is connected to the grid of the dimming MOS tube Q2, the ISEN pin and one end of the fifth resistor R5 are connected to the source of the dimming MOS tube Q2, the other end of the fifth resistor R5 is grounded, and the drain of the dimming MOS tube Q2 is connected with the backlight module.
The ADRI pin is a driving pin of a dimming MOS tube Q2, and the ISEN pin is a power detection current pin of the booster circuit. The dimming MOS transistor Q2 is combined with the dimming control unit 30 to form a dimming control circuit for adjusting the current of the backlight module; the fifth resistor R5 is a current sampling resistor. Of course, the dimming MOS transistor Q2 and the fifth resistor R5 may be integrated in the chip body 100, besides being disposed at the periphery of the chip body 100.
In addition, the chip body 100 is further provided with an LPF pin, and the LPF pin is grounded through a capacitor C2. The LPF pin is a low-pass filter pin and is used for performing direct current conversion on an input dimming pulse signal CPWM to obtain a direct current level signal. The CPWM signal is outputted to the backlight control circuit through the dimming control unit 30 circuit corresponding to different level values under different duty ratios, and is used as the adjusting reference voltage of the dimming MOS transistor Q2.
In addition, the present invention further provides a backlight driving adjustment method, please refer to fig. 2, which is a flowchart of the backlight driving adjustment method, and the backlight driving adjustment method includes the following steps:
s100, selecting and setting a segmented dimming voltage;
s200, receiving a dimming pulse signal sent by a main board;
s300, selecting a dimming mode of the backlight module according to the value of the segmented dimming voltage and the duty ratio of the dimming pulse signal, and adjusting and driving the backlight module.
Specifically, referring to fig. 3, the step S100 includes:
s110, obtaining a fixed reference voltage;
and S120, dividing the reference voltage to obtain a segmented dimming voltage, and performing comparator array and algorithm control on the segmented dimming voltage to obtain different dimming intervals.
Through the ADIM pin function of the backlight driving adjustment chip, that is, the voltage of the ADIM pin is obtained by dividing the internal reference voltage VREF through the voltage dividing unit 50, and after passing through the comparator array of the segmented dimming voltage setting unit 20, the ADIM pin and the dimming control unit 30 are subjected to algorithm control, so that different ADIM voltage settings are obtained, and the segmented dimming gears for setting the analog dimming and the PWM dimming are selected corresponding to the control of different external input CPWM signal duty ratios.
The segmented dimming gear of the backlight driving and adjusting chip can be flexibly set according to needs, for example, when the set dimming gear is A%, when the duty ratio of a dimming pulse signal is 0-A%, the module is controlled to be backlight by adopting a PWM dimming mode; and when the duty ratio of the dimming pulse signal is more than A%, analog dimming is adopted, so that the hybrid dimming function is realized.
Specifically, referring to fig. 4, the step S200 includes:
s210, receiving a dimming pulse signal sent by a main board;
and S220, performing direct current conversion on the dimming pulse signal to obtain direct current conversion voltage corresponding to the duty ratio of the dimming pulse signal.
In the dimming control chip, the input dimming pulse signal CPWM can be subjected to direct current conversion through an LPF pin to obtain a direct current level signal. The CPWM signal is outputted to the backlight control unit 10 through the dimming control unit 30 as the adjusting reference voltage of the dimming MOS transistor Q2 corresponding to different level values at different duty ratios.
Specifically, referring to fig. 5, the step S220 includes:
s221, when the duty ratio of the pulse dimming signal is 100%, the corresponding direct current conversion voltage is a 1V;
s222, when the duty ratio of the pulse dimming signal is 50%, the corresponding direct current conversion voltage is 0.5a 1V;
s223, when the duty ratio of the pulse dimming signal is D%, the corresponding direct current conversion voltage is a 2V;
s224, when the duty ratio of the pulse dimming signal is C%, the corresponding direct current conversion voltage is a 3V;
s225, when the duty ratio of the pulse dimming signal is B%, the corresponding direct current conversion voltage is a 4V;
s226, when the duty ratio of the pulse dimming signal is A%, the corresponding direct current conversion voltage is a 5V;
s227, when the duty ratio of the pulse dimming signal is 0%, the corresponding direct current conversion voltage is 0V;
wherein 0< a < B < C < D <100,0< a5< a4< a3< a2< a 1; the duty ratio of the pulse dimming signal and the corresponding direct current conversion voltage are in a linear corresponding relation.
Then, the voltage V is converted into DCLPFAfter the conversion by the dimming control unit 30, the ISEN regulated voltage V of the backlight regulating unit 70 is outputtedADJ，VADJHas a voltage value of V LPF1/H of the voltage value of (1), wherein H is a predetermined constant. By mixing VADJInto the backlight control unit 10, ISEN passes VADJThe adjustment is performed, and then the current of the backlight module 40 is adjusted by the backlight adjusting unit 70, so as to finally control the backlight brightness of the whole device.
In addition, referring to fig. 6, the step S300 specifically includes:
s310, when the segmented dimming voltage is less than a volt, if the duty ratio of the dimming pulse signal is less than A%, the dimming mode is a PWM dimming mode; if the duty ratio of the dimming pulse signal is more than A%, the dimming mode is an analog dimming mode;
s320, when the segmented dimming voltage is larger than a volt and smaller than B volt, if the duty ratio of the dimming pulse signal is smaller than B%, the dimming mode is a PWM dimming mode; if the duty ratio of the dimming pulse signal is greater than B%, the dimming mode is an analog dimming mode;
s330, when the segmented dimming voltage is greater than b volt and less than C volt, if the duty ratio of the dimming pulse signal is less than C%, the dimming mode is a PWM dimming mode; if the duty ratio of the dimming pulse signal is larger than C%, the dimming mode is an analog dimming mode;
s340, when the segmented dimming voltage is larger than c volts, if the duty ratio of the dimming pulse signal is smaller than D%, the dimming mode is a PWM dimming mode; if the duty ratio of the dimming pulse signal is larger than D%, the dimming mode is an analog dimming mode;
s350, adjusting and driving the backlight module after the dimming mode of the backlight module is selected;
wherein A < B < C < D, a < B < C. A. B, C, D, and the values of a, b and c can be set according to actual needs, so that the backlight driving adjustment chip has a plurality of dimming ranges.
When dimming pulse signals input by the CPWM pin are respectively 100% -D%/C%/B%/A%, the backlight driving adjusting chip works in a simulation dimming mode. And in the analog dimming mode, the maximum duty ratio of dimming is 100%. At this time, the ISEN regulation voltage of the analog dimming is VADJ（VLPFH). When the input duty cycle of the CPWM signal is less than D%/C%/B%/a%, the dimming duty cycle starts from 100%, and the regulated voltage of ISEN goes from analog dimming to PWM dimming as the duty cycle of the CPWM signal decreases.
Referring to fig. 1, the DIM signal output by the dimming control unit 30 is an internal dimming signal with a fixed frequency fDIM(typically greater than 20KHz, greater than the noise range recognizable by the human ear). When the duty ratio of the external CPWM signal is lower than D%/C%/B%/A%, the constant current chip works in the PWM mode, and the duty ratio of the internal dimming signal starts to start from the beginning along with the reduction of the duty ratio of the external dimming signal CPWMThe 100% is gradually decreased so as to control the brightness adjustment of the backlight of the module.
The backlight driving and adjusting method can achieve the following effects:
1) the dimming full range control of the backlight module is realized, and the limitation of the dimming range under the analog dimming mode is avoided;
2) in the analog dimming range, the lighting effect of the backlight module is effectively improved; within the PWM dimming range, the linearity of the dimming range of the backlight module is ensured;
3) the problem of noise of dimming inductors in single PWM dimming is solved;
4) the problem of picture rolling interference caused by beat interference between PWM dimming frequency and LED glass field frequency is solved, and the picture quality and the display effect of televisions and other display equipment are improved.
Moreover, after the design scheme provided by the invention is used, the software of the external mainboard does not need to be adjusted, and the scheme has strong compatibility; the external PWM signal is converted into an ADIM signal without an external RC circuit, and is directly sent into a chip for processing through a CPWM pin, so that the reliability is higher.
Therefore, the invention provides a method for realizing the segmented mixed dimming combining the analog dimming and the PWM dimming by the design of the constant current scheme under the condition of not changing the dimming frequency of the dimming pulse signal output by the main board, and realizes the dimming full-range control of the LED backlight module by utilizing the advantages of respective dimming. The sectional type mixed dimming technology improves the lighting effect of the backlight module under the PWM dimming mode, solves the problem of noise of dimming inductance in a single PWM dimming mode, eliminates the problem of rolling interference of pictures caused by beat interference between PWM dimming frequency and LED glass field frequency, and has universal application value in improving the picture quality and display effect of televisions and other display equipment. Meanwhile, the technical scheme of the invention improves the display effect and the picture quality of display equipment such as televisions and the like, and has important popularization value.
In summary, the present invention provides a backlight driving and adjusting circuit, a chip and a method, wherein the backlight driving and adjusting circuit includes: the backlight control unit is used for driving and controlling the backlight module; a segment dimming voltage setting unit for setting a segment dimming voltage; the dimming control unit is used for carrying out dimming algorithm control on the dimming pulse signal; the segmented dimming voltage setting unit is connected with the dimming control unit, and the dimming control unit is connected with the backlight control unit. The invention realizes the mixed dimming function through the backlight driving and adjusting circuit, the chip and the method, solves the noise problem of dimming inductance in a single PWM dimming mode, eliminates the problem of rolling interference of pictures caused by beat interference, and effectively improves the picture quality and the display effect of televisions and other display equipment.
It should be understood that equivalents and modifications of the technical solution and inventive concept thereof may occur to those skilled in the art, and all such modifications and alterations should fall within the scope of the appended claims.
Claims (8)
1. A backlight driving and adjusting circuit, comprising:
backlight control unit for driving and controlling backlight module
A segment dimming voltage setting unit for setting a segment dimming voltage;
the dimming control unit is used for carrying out dimming algorithm control on the dimming pulse signal;
the segmented dimming voltage setting unit is connected with the dimming control unit, and the dimming control unit is connected with the backlight control unit;
the segmented dimming voltage setting unit comprises a comparator array formed by a plurality of comparators, the comparator array is connected with the dimming control unit and is used for setting different segmented dimming voltages according to the division of the reference voltage, and the segmented dimming voltages correspond to different control threshold values of the duty ratio of the external input dimming pulse signal;
selecting a dimming mode of the backlight module according to the value of the segmented dimming voltage and the duty ratio of the dimming pulse signal, and adjusting and driving the backlight module;
when the segmented dimming voltage is less than a volt, if the duty ratio of the dimming pulse signal is less than A%, the dimming mode is a PWM dimming mode; if the duty ratio of the dimming pulse signal is more than A%, the dimming mode is an analog dimming mode;
when the segmented dimming voltage is larger than a volt and smaller than B volt, if the duty ratio of the dimming pulse signal is smaller than B%, the dimming mode is a PWM dimming mode; if the duty ratio of the dimming pulse signal is greater than B%, the dimming mode is an analog dimming mode;
when the segmented dimming voltage is greater than b volt and less than C volt, if the duty ratio of the dimming pulse signal is less than C%, the dimming mode is a PWM dimming mode; if the duty ratio of the dimming pulse signal is larger than C%, the dimming mode is an analog dimming mode;
when the segmented dimming voltage is larger than c volts, if the duty ratio of the dimming pulse signal is smaller than D%, the dimming mode is a PWM dimming mode; if the duty ratio of the dimming pulse signal is larger than D%, the dimming mode is an analog dimming mode;
after the dimming mode of the backlight module is selected, the backlight module is adjusted and driven;
wherein 0< a < B < C < D <100,0< a < B < C.
2. The backlight driving and adjusting circuit of claim 1, further comprising a voltage dividing unit, wherein the voltage dividing unit comprises a first resistor and a second resistor, one end of the first resistor is inputted with a reference voltage, and the other end of the first resistor is respectively connected to one end of the second resistor and the segment dimming voltage setting unit.
3. The backlight driving and regulating circuit of claim 1, further comprising a boost power unit, wherein the boost power unit comprises a boost inductor, a boost MOS transistor, a first diode, an output capacitor, a third resistor and a fourth resistor, one end of the boost inductor inputs VIN voltage, the other end of the boost inductor is connected to the drain of the boost MOS transistor and the anode of the first diode respectively, one end of the output capacitor is connected to the cathode of the first diode and outputs backlight voltage to the backlight module, the other end of the output capacitor is grounded, the gate of the boost MOS transistor is connected to the backlight control unit, the source of the boost MOS transistor is connected to one end of the third resistor and one end of the fourth resistor, the other end of the third resistor is grounded, and the other end of the fourth resistor is connected to the backlight control unit.
4. The backlight driving and adjusting circuit of claim 1, further comprising a backlight adjusting unit, wherein the backlight adjusting unit comprises a dimming MOS transistor and a fifth resistor, a gate of the dimming MOS transistor is connected to the backlight control unit, a source of the dimming MOS transistor is connected to one end of the backlight control unit and one end of the fifth resistor, another end of the fifth resistor is grounded, and a drain of the dimming MOS transistor is connected to the backlight module.
5. A backlight driving adjustment chip, characterized in that the backlight driving adjustment chip comprises a chip body, on which the backlight driving adjustment circuit according to any one of claims 1-4 is integrated.
6. A backlight driving adjustment method is characterized by comprising the following steps:
setting a value of the segment dimming voltage;
receiving a dimming pulse signal sent by a main board and obtaining the duty ratio of the dimming pulse signal;
selecting a dimming mode of the backlight module according to the value of the segmented dimming voltage and the duty ratio of the dimming pulse signal, and adjusting and driving the backlight module;
the step of setting the segmented dimming voltage specifically comprises:
acquiring a fixed reference voltage;
dividing the reference voltage to obtain a segmented dimming voltage, and performing comparator array and algorithm control on the segmented dimming voltage to obtain different dimming intervals;
the step of selecting the dimming mode of the backlight module according to the value of the segmented dimming voltage and the duty ratio of the dimming pulse signal, and adjusting and driving the backlight module specifically comprises:
when the segmented dimming voltage is less than a volt, if the duty ratio of the dimming pulse signal is less than A%, the dimming mode is a PWM dimming mode; if the duty ratio of the dimming pulse signal is more than A%, the dimming mode is an analog dimming mode;
when the segmented dimming voltage is larger than a volt and smaller than B volt, if the duty ratio of the dimming pulse signal is smaller than B%, the dimming mode is a PWM dimming mode; if the duty ratio of the dimming pulse signal is greater than B%, the dimming mode is an analog dimming mode;
when the segmented dimming voltage is greater than b volt and less than C volt, if the duty ratio of the dimming pulse signal is less than C%, the dimming mode is a PWM dimming mode; if the duty ratio of the dimming pulse signal is larger than C%, the dimming mode is an analog dimming mode;
when the segmented dimming voltage is larger than c volts, if the duty ratio of the dimming pulse signal is smaller than D%, the dimming mode is a PWM dimming mode; if the duty ratio of the dimming pulse signal is larger than D%, the dimming mode is an analog dimming mode;
after the dimming mode of the backlight module is selected, the backlight module is adjusted and driven;
wherein 0< a < B < C < D <100,0< a < B < C.
7. The backlight driving adjustment method according to claim 6, wherein the step of receiving the dimming pulse signal sent by the motherboard and obtaining the duty ratio of the dimming pulse signal specifically comprises:
receiving a dimming pulse signal sent by a main board;
and performing direct current conversion on the dimming pulse signal to obtain direct current conversion voltage corresponding to the duty ratio of the dimming pulse signal.
8. The backlight driving adjustment method according to claim 7, wherein the step of performing dc conversion on the dimming pulse signal to obtain a dc conversion voltage corresponding to a duty ratio of the dimming pulse signal specifically comprises:
when the duty ratio of the pulse dimming signal is 100%, the corresponding direct current conversion voltage is a 1;
when the duty ratio of the pulse dimming signal is 50%, the corresponding direct current conversion voltage is 0.5a 1;
when the duty ratio of the pulse dimming signal is D%, the corresponding direct current conversion voltage is a 2;
when the duty ratio of the pulse dimming signal is C%, the corresponding direct current conversion voltage is a 3;
when the duty ratio of the pulse dimming signal is B%, the corresponding direct current conversion voltage is a 4;
when the duty ratio of the pulse dimming signal is A%, the corresponding direct current conversion voltage is a 5;
when the duty ratio of the pulse dimming signal is 0%, the corresponding direct current conversion voltage is 0;
wherein 0< a < B < C < D <100,0< a5< a4< a3< a2< a 1.
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