CN112581916A - Dimming circuit of backlight module, dimming method of dimming circuit and display device - Google Patents
Dimming circuit of backlight module, dimming method of dimming circuit and display device Download PDFInfo
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- CN112581916A CN112581916A CN202011471087.2A CN202011471087A CN112581916A CN 112581916 A CN112581916 A CN 112581916A CN 202011471087 A CN202011471087 A CN 202011471087A CN 112581916 A CN112581916 A CN 112581916A
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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
- 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
- G09G3/3413—Details of control of colour illumination sources
Abstract
The invention provides a dimming circuit of a backlight module, a dimming method and a display device thereof, wherein the dimming circuit comprises a clock generator for copying a target PWM signal output by a driving board according to a current display picture into a first PWM signal, a second PWM signal and a third PWM signal, the first PWM signal is directly input to a microcontroller, the second PWM signal is input to the microcontroller through a second sub-PWM signal modulated by a first gate circuit, and the third PWM signal is input to the microcontroller through a third sub-PWM signal modulated by a second gate circuit; the microcontroller is used for: determining the level state of the target PWM signal according to the first path of PWM signal, determining the edge jump time of the target PWM signal according to the second sub-path PWM signal and the third sub-path PWM signal, determining the duty ratio of the target PWM signal according to the level state and the edge jump time, and adjusting the brightness output to the backlight source according to the duty ratio.
Description
Technical Field
The invention relates to the technical field of display, in particular to a dimming circuit of a backlight module, a dimming method of the dimming circuit and a display device.
Background
In the conventional backlight control, Pulse Width Modulation (PWM) dimming is often used to adjust the backlight brightness, specifically, a PWM signal is generated by a complete machine driving board or a System On Chip (SOC), and the PWM signal is directly used to adjust the backlight brightness.
At present, the PWM signal is usually acquired through the rising edge time and the falling edge time of the waveform, on one hand, the rising edge time and the falling edge time of the waveform corresponding to the PWM signal are usually only microsecond level, and particularly, the falling edge time is too short, so that the acquisition error is easy to occur, and the backlight adjustment quality is influenced. On the other hand, signals with too high or too low duty ratio cannot be distinguished, for example, 0% and 100%, and are prone to brightness jump.
Therefore, the conventional backlight brightness is low in adjustment efficiency, and the display quality is further reduced.
Disclosure of Invention
The invention provides a dimming circuit of a backlight module, a dimming method thereof and a display device, which are used for improving the adjusting efficiency of backlight brightness and further improving the display quality.
In a first aspect, an embodiment of the present invention provides a dimming circuit of a backlight module, including:
a driver board, a clock generator electrically connected to the driver board, a gate circuit electrically connected to the clock generator, and a microcontroller electrically connected to the gate circuit, the gate circuit including a first gate circuit and a second gate circuit, wherein:
the clock generator is used for copying a target PWM signal output by the driving board according to a current display picture into a first PWM signal, a second PWM signal and a third PWM signal, the first PWM signal is directly input to the microcontroller, the second PWM signal is input to the microcontroller through a second sub-circuit PWM signal modulated by the first gate circuit, the third PWM signal is input to the microcontroller through a third sub-circuit PWM signal modulated by the second gate circuit, and the second sub-circuit PWM signal and the third sub-circuit PWM signal are in reverse symmetry;
the microcontroller is configured to:
determining the high-low level state of the target PWM signal according to the first path of PWM signal, determining the edge jumping time of the target PWM signal according to the second sub-path PWM signal and the third sub-path PWM signal, determining the duty ratio of the target PWM signal according to the high-low level state and the edge jumping time, and adjusting the brightness output to the backlight source according to the duty ratio.
In one possible implementation, the microcontroller is specifically configured to:
if the first path of PWM signal is detected to be high level, determining that the target PWM signal is high level;
and if the first path of PWM signal is detected to be at a low level, determining that the target PWM signal is at a low level.
In a possible implementation manner, if the target PWM signal is at a high level, the microcontroller is specifically configured to:
respectively detecting a first moment of a rising edge of the second sub-circuit PWM signal, and after the first moment, a second moment of a rising edge of the third sub-circuit PWM signal, and determining a difference value between the second moment and the first moment as a first duration of the target PWM signal keeping the high level in one signal detection period;
if the target PWM signal is at a low level, respectively detecting a third time of a rising edge of the third sub-PWM signal, and after the third time, a fourth time of a rising edge of the second sub-PWM signal, and determining a difference between the fourth time and the third time as a second duration of the target PWM signal maintaining the low level in the signal detection period;
adding the first duration and the second duration to determine a total duration, wherein the total duration is a duration corresponding to the signal detection period;
determining a ratio of the first duration to the total duration, the ratio being determined as a duty cycle of the target PWM signal during the signal detection period.
In a possible implementation manner, if the microcontroller does not detect a rising edge of any one of the second sub-circuit PWM signal and the third sub-circuit PWM signal, the microcontroller is specifically configured to:
keeping the duty ratio of the target PWM signal unchanged.
In a possible implementation manner, if the microcontroller does not detect the rising edge of the second sub-circuit PWM signal and the rising edge of the third sub-circuit PWM signal, the microcontroller is specifically configured to:
if the target PWM signal is at a high level, controlling the duty ratio of the target PWM signal to be a preset maximum value, and adjusting the brightness of the backlight source to be a brightness maximum value according to the preset maximum value;
and if the target PWM signal is at a low level, controlling the duty ratio of the target PWM signal to be a preset minimum value, and adjusting the brightness of the backlight source to be a brightness minimum value according to the preset minimum value.
In a possible implementation manner, the first gate circuit is an and gate, a first input end of the and gate is electrically connected to an output end of the clock generator, a second input end of the and gate is electrically connected to a first preset high potential end, and an output end of the and gate is electrically connected to a first port of the microcontroller.
In a possible implementation manner, the second gate circuit is a nand gate, a third input terminal of the nand gate is electrically connected to the output terminal of the clock generator, a fourth input terminal of the nand gate is electrically connected to the second preset high potential terminal, and an output terminal of the nand gate is electrically connected to the second port of the microcontroller.
In a second aspect, an embodiment of the present invention provides a display device, including:
a display panel;
the backlight module comprises a backlight source and the dimming circuit of the backlight module, wherein the dimming circuit is used for adjusting the brightness of the backlight source.
In a third aspect, an embodiment of the present invention provides a dimming method using the dimming circuit of the backlight module, including:
generating a target PWM signal through the driving board according to a current display picture;
copying the target PWM signal into a first PWM signal, a second PWM signal and a third PWM signal through the clock generator, wherein the first PWM signal is directly input to the microcontroller, the second PWM signal is input to the microcontroller through a second sub-PWM signal modulated by a first gate circuit, and the third PWM signal is input to a third port of the controller through a third sub-PWM signal modulated by a second gate circuit, wherein the second sub-PWM signal and the third sub-PWM signal are in inverse symmetry;
determining the high-low level state of the current PWM signal by the target PWM signal through the microcontroller, determining the edge jump time of the target PWM signal according to the second sub-PWM signal and the third sub-PWM signal, determining the duty ratio of the target PWM signal according to the high-low level state and the edge jump time, and adjusting the brightness output to the backlight source according to the duty ratio.
In one possible implementation, the determining, by the microcontroller, the target PWM signal to determine the high-low level state of the current-path PWM signal includes:
if the microcontroller detects that the first path of PWM signal is at a high level, the target PWM signal is determined to be at the high level;
and determining that the target PWM signal is at a low level when the microcontroller detects that the first PWM signal is at a low level.
The invention has the following beneficial effects:
the embodiment of the invention provides a dimming circuit of a backlight module, a dimming method thereof and a display device, wherein the dimming circuit comprises a driving board, a clock generator electrically connected with the driving board, a gate circuit electrically connected with the clock generator and a microcontroller electrically connected with the gate circuit, wherein the clock generator is used for copying a target PWM signal output by the driving board according to a current display picture into a first PWM signal, a second PWM signal and a third PWM signal, namely the PWM signals are copied into three identical output signals, the first PWM signal is input into the microcontroller through a second sub-PWM signal modulated by a first gate circuit in the gate circuit, namely the first PWM signal is input into the microcontroller through a signal modulated by the first gate circuit, and the third PWM signal is input into the microcontroller through a third sub-PWM signal modulated by a second gate circuit in the gate circuit The microcontroller is configured to input a signal modulated by the third PWM signal through the second gate circuit to the microcontroller, where the modulated second sub-PWM signal and the third sub-PWM signal are in inverse symmetry, and the microcontroller is configured to determine a high-low level state of the target PWM signal according to the first PWM signal, determine a moment when an edge of the target PWM signal jumps according to the second sub-PWM signal and the third sub-PWM signal, determine a duty cycle of the target PWM signal according to the high-low level state and the moment when the edge jumps, and then adjust the brightness output to the backlight according to the duty cycle. That is to say, a clock generator in the dimming circuit copies a target PWM signal output by the driving board into three identical signals, one of the three identical signals is used for judging the high-low level state of the target PWM signal, the other two identical signals are used for acquiring the edge jump time of the target PWM signal, and the high-low level state and the edge jump time are used for jointly determining the acquired PWM signal, so that the brightness jump is avoided, the backlight brightness adjustment efficiency is improved, and the display quality is further improved.
Drawings
Fig. 1 is a schematic structural diagram of a dimming circuit of a backlight module according to an embodiment of the present invention;
fig. 2 is a schematic diagram illustrating a correspondence relationship between a target PWM signal and one of a timing sequence and a waveform between a first sub-PWM signal, a second sub-PWM signal, and a third sub-PWM signal in a dimming circuit of a backlight module according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a dimming circuit of a backlight module according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a dimming circuit of a backlight module according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a dimming circuit of a backlight module according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of a display device according to an embodiment of the present invention;
fig. 7 is a flowchart of a method of dimming by using a dimming circuit of a backlight module according to an embodiment of the present invention;
fig. 8 is a step in step S103 in fig. 7: determining, by the microcontroller, the target PWM signal to determine one of a high-low level state of a current-path PWM signal;
fig. 9 is a step in step S103 in fig. 7: and determining the duty ratio of the target PWM signal according to the high-low level state and the time of the edge jump.
Description of reference numerals:
1-a drive plate; 2-a clock generator; a 3-gate circuit; 4-a microcontroller; 41-a first port; 42-a second port; 31-a first gate circuit; 311-a first input terminal; 312 — a second input; 32-a second gate circuit; 321-a third input terminal; 322-a fourth input terminal; 5-a first preset high potential end; 10-a display panel; 20-a backlight module; 21-a backlight source; 22-dimming circuit.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the drawings of the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. And the embodiments and features of the embodiments may be combined with each other without conflict. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention without any inventive step, are within the scope of protection of the invention.
Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. The use of the word "comprise" or "comprises", and the like, in the context of this application, is intended to mean that the elements or items listed before that word, in addition to those listed after that word, do not exclude other elements or items.
It should be noted that the sizes and shapes of the figures in the drawings are not to be considered true scale, but are merely intended to schematically illustrate the present invention. And the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.
In the prior art, the collection precision of the receiving end on the PWM signal is often influenced by the sampling frequency, for example, the PWM signal is 120Hz, and when the sampling precision is 1% brightness, the sampling frequency is at least 24KHz, and in order to improve the brightness collection precision and further improve the dynamic contrast, the collection precision can be improved from 1% to 0.1%, accordingly, the sampling frequency needs to be at least 240KHz, and the higher sampling frequency can influence the use performance of the device to a certain extent. In addition, at present, the PWM signal is usually acquired through the rising edge time and the falling edge time of the waveform, on one hand, the rising edge time and the falling edge time of the waveform corresponding to the PWM signal are usually only microsecond level, and particularly, the falling edge time is too short, so that the acquisition error is easy to occur, and the backlight adjustment quality is affected. On the other hand, signals with too high or too low duty ratios, for example, 0% and 100%, cannot be distinguished, and no clear judgment can be given. In practical application, once external conditions change, such as temperature and signal source, the single chip microcomputer has a problem in identifying the PWM signal, which may result in brightness loss or brightness flicker.
As a specific example, the backlight module having Local Dimming (Local Dimming) function usually employs the following Dimming strategy: when no signal change can be acquired, the brightness is forced to be set to 100%. However, at this time, the actual luminance is likely to be 0%, and thus, the luminance may be instantaneously changed, and if the luminance is located at the signal detectable boundary, the luminance may repeatedly flicker, so that the entire backlight luminance may be adjusted with low efficiency, and the display quality may be affected.
In view of this, embodiments of the present invention provide a dimming circuit of a backlight module, a dimming method thereof, and a display device, which are used to improve the efficiency of adjusting the backlight brightness and ensure the display quality.
Fig. 1 shows a dimming circuit of a backlight module according to an embodiment of the present invention, which includes:
a driver board 1, a clock generator 2 electrically connected to the driver board 1, a gate circuit 3 electrically connected to the clock generator 2, and a microcontroller 4 electrically connected to the gate circuit 3, the gate circuit 3 including a first gate circuit 31 and a second gate circuit 32, wherein:
the clock generator 2 is configured to copy a target PWM signal output by the driving board 1 according to a current display picture into a first PWM signal, a second PWM signal, and a third PWM signal, where the first PWM signal is directly input to the microcontroller 4, the second PWM signal is input to the microcontroller 4 via a second sub-PWM signal modulated by a first gate circuit 31, and the third PWM signal is input to the microcontroller 4 via a third sub-PWM signal modulated by a second gate circuit 32, where the second sub-PWM signal and the third sub-PWM signal are in inverse symmetry;
the microcontroller 4 is configured to:
determining the high-low level state of the target PWM signal according to the first path of PWM signal, determining the edge jumping time of the target PWM signal according to the second sub-path PWM signal and the third sub-path PWM signal, determining the duty ratio of the target PWM signal according to the high-low level state and the edge jumping time, and adjusting the brightness output to the backlight source according to the duty ratio.
In the embodiment of the invention, a clock generator 2 in a dimming circuit copies a target PWM signal output by a driving board 1 into three identical signals, wherein one signal is used for judging the high-low level state of the target PWM signal, the other two signals are used for collecting the edge jump time of the target PWM signal, and the collected target PWM signal is jointly determined by the high-low level state and the edge jump time, wherein the collection of the edge jump time of the target PWM signal is two interrupt collections, so that the problem that the signal collection is influenced by insufficient interrupt speed is avoided.
In a specific implementation process, the second sub-circuit PWM signals and the third sub-circuit PWM signals are in inverse symmetry, so that when the target PWM signals are collected, the signal collection process can be converted into the collection of the rising edge, the collection of the falling edge is avoided, and the efficiency of signal collection is further ensured.
In the embodiment of the present invention, the microcontroller 4 is specifically configured to:
if the first path of PWM signal is detected to be high level, determining that the target PWM signal is high level;
and if the first path of PWM signal is detected to be at a low level, determining that the target PWM signal is at a low level.
In a specific implementation process, the first path of PWM signal is used for acquiring a high-low level state, and since the first path of PWM signal is directly input to the microcontroller 4, the first path of PWM signal is substantially identical to the target PWM signal, and therefore, the microcontroller 4 can determine a current state of the target PWM signal according to the acquired level state of the first path of PWM signal, and determine whether to start timing the target PWM signal. Specifically, if the first PWM signal is detected to be at a high level, the target PWM signal is determined to be at a high level, and if the first PWM signal is detected to be at a low level, the target PWM signal is determined to be at a low level, so that the acquisition of the high-low level state of the target PWM signal is realized by acquiring the level state of the first PWM signal.
In the embodiment of the present invention, if the target PWM signal is at a high level, the microcontroller 4 is specifically configured to:
respectively detecting a first moment of a rising edge of the second sub-circuit PWM signal, and after the first moment, a second moment of a rising edge of the third sub-circuit PWM signal, and determining a difference value between the second moment and the first moment as a first duration of the target PWM signal keeping the high level in one signal detection period;
if the target PWM signal is at a low level, respectively detecting a third time of a rising edge of the third sub-PWM signal, and after the third time, a fourth time of a rising edge of the second sub-PWM signal, and determining a difference between the fourth time and the third time as a second duration of the target PWM signal maintaining the low level in the signal detection period;
adding the first duration and the second duration to determine a total duration, wherein the total duration is a duration corresponding to the signal detection period;
determining a ratio of the first duration to the total duration, the ratio being determined as a duty cycle of the target PWM signal during the signal detection period.
In a specific implementation process, as shown in fig. 2, a schematic diagram of a corresponding relationship between a target PWM signal and one of a timing sequence and a waveform between a first sub-PWM signal, a second sub-PWM signal, and a third sub-PWM signal is shown, where the target PWM signal is a rectangular wave pulse signal, and an arc line in fig. 2 is an actual output waveform of the corresponding signal. The first PWM signal is substantially identical to the target PWM signal, and the waveform of the second sub-PWM signal is substantially identical to the waveform of the target PWM signal, but due to the delay characteristic of the device of the first gate circuit 31, the second sub-PWM signal is slightly delayed in time sequence compared with the first PWM signal. In this way, by using the delay characteristic of the first gate circuit 31, after the microcontroller 4 detects the level state of the first PWM signal, the second sub-PWM signal can be collected for the rising edge, so that the efficiency of signal collection is improved. In addition, the second sub-circuit PWM signals and the third sub-circuit PWM signals are in reverse symmetry, and therefore the time sequences of the second sub-circuit PWM signals and the third sub-circuit PWM signals are consistent, and the quality of signal acquisition is further guaranteed.
In a specific implementation process, as shown in fig. 2, in one signal detection period T, a time duration corresponding to one signal detection period T is (T1+ T2). If the target PWM signal is at a high level, and correspondingly, the first PWM signal is at a high level, at this time, detection of a high level time may be started, a first time of a rising edge of the second sub-PWM signal is detected, a second time of a rising edge of the third sub-PWM signal is detected, and a difference between the second time and the first time is determined as a first duration of the target PWM signal maintaining the high level in the signal detection period, for example, at t1 shown in fig. 2.
In a specific implementation process, still referring to fig. 2, if the target PWM signal is at a low level, and accordingly, the first PWM signal is at a low level, at this time, detection of a low level time may be started, a third time of a rising edge of the third sub-PWM signal is detected, a fourth time of a rising edge of the second sub-PWM signal is detected, and a difference between the fourth time and the third time is determined as a second duration t2, for example, t2 shown in fig. 2, during which the target PWM signal keeps at the low level in the signal detection period.
In an implementation, after the first duration and the second duration are determined, the first duration and the second duration may be added to determine a duration corresponding to a signal detection period, and still taking fig. 2 as an example, the duration corresponding to a signal detection period T is (T1+ T2). Then, a ratio of the first duration to the total duration is determined, and the ratio is determined as a duty ratio of the target PWM signal in the signal detection period, taking fig. 2 as an example, the duty ratio P of the target PWM signal maintaining the high level in the signal detection period T may be P ═ T1/(T1+ T2) × 100%, and then the luminance of the backlight source may be adjusted according to the duty ratio. In a specific implementation process, the rising edge time of the second sub-path PWM signal and the rising edge time of the third sub-path PWM signal are detected, so that the time difference between the second sub-path PWM signal and the third sub-path PWM signal is determined, the duty ratio time in a signal detection period is further calculated, the falling edge time is not detected in the whole detection process any more, the starting time and the ending time of a high level and the starting time and the ending time of a low level in the signal detection period are detected by using two interrupts in turn, and the signal acquisition efficiency is improved.
In this embodiment of the present invention, if the microcontroller 4 cannot detect a rising edge of any one of the second sub-circuit PWM signal and the third sub-circuit PWM signal, the microcontroller 4 is specifically configured to:
keeping the duty ratio of the target PWM signal unchanged.
In a specific implementation process, since the second sub-circuit PWM signal and the third sub-circuit PWM signal are both derived from the same signal source, as long as one signal is not detected, the microcontroller 4 may determine the current state as an abnormal state, and at this time, the duty ratio of the target PWM signal is kept unchanged, thereby avoiding brightness jump and improving display quality.
In this embodiment of the present invention, if the microcontroller 4 cannot detect the rising edge of the second sub-circuit PWM signal and the rising edge of the third sub-circuit PWM signal, the microcontroller 4 is specifically configured to:
if the target PWM signal is at a high level, controlling the duty ratio of the target PWM signal to be a preset maximum value, and adjusting the brightness of the backlight source to be a brightness maximum value according to the preset maximum value;
and if the target PWM signal is at a low level, controlling the duty ratio of the target PWM signal to be a preset minimum value, and adjusting the brightness of the backlight source to be a brightness minimum value according to the preset minimum value.
In a specific implementation process, if the microcontroller 4 cannot detect a rising edge, the actual level state of the target PWM signal may be determined according to the collected level state of the first path of PWM signal, if the target PWM signal is at a high level, the duty ratio of the target PWM signal is controlled to be a preset maximum value, where the preset maximum value is a preset value, for example, 100%, and then the brightness of the backlight source is adjusted to be the maximum brightness value according to the preset maximum value. In addition, if the target PWM signal is at a low level, the duty ratio of the target PWM signal is controlled to be a preset minimum value, for example, 0%, and then the luminance of the backlight source is adjusted to be the minimum luminance value according to the preset minimum value. Therefore, no matter what the level state of the target PWM signal is, the duty ratio of the target PWM signal can be set according to the actual level value of the target PWM signal, so that brightness jump is avoided, and the display quality is improved.
In the embodiment of the present invention, as shown in fig. 3, it is a schematic diagram of one of the structures of the dimming circuit, specifically, the first gate circuit 31 is an and gate, a first input terminal 311 of the and gate is electrically connected to the output terminal of the clock generator 2, a second input terminal 312 of the and gate is electrically connected to the first preset high potential terminal 5, and an output terminal of the and gate is electrically connected to the first port 41 of the microcontroller 4.
In a specific implementation process, the first preset high potential terminal 5 may be a potential terminal set by an external power supply, or a potential terminal output by a power supply shared by the driving board 1, which is not limited herein. Before the second path of PWM signals enters the microcontroller 4, the AND gate can be used for performing AND operation on the second path of PWM signals and the first preset high potential end, so that the second sub-path PWM signals modulated by the AND gate are obtained, interference is reduced in the AND gate modulation process, and the quality of the second sub-path PWM signals is improved.
In the embodiment of the present invention, as shown in fig. 4, it is a schematic structural diagram of a dimming circuit, specifically, the second gate circuit 32 is a nand gate, a third input 321 of the nand gate is electrically connected to the output of the clock generator 2, a fourth input 322 of the nand gate is electrically connected to the second preset high potential terminal, and an output of the nand gate is electrically connected to the second port 42 of the microcontroller 4.
In a specific implementation, the second preset high potential terminal may be the same potential terminal as the first preset high potential terminal, as shown in fig. 4, or may be a different potential terminal, and specifically, the second preset high potential terminal may be a potential terminal set by an external power supply, or a potential terminal output by a power supply shared by the driving board 1, which is not limited herein. Before the third PWM signal enters the microcontroller 4, the nand gate may perform a nand operation on the third PWM signal and the second preset high potential end, so as to obtain the third sub-PWM signal modulated by the nand gate.
Referring to fig. 3 and 4, fig. 5 is a schematic diagram of one of the structures of the dimming circuit. In a specific implementation process, due to the fact that delay effects of device characteristics of the AND gate and the NAND gate are approximately the same, a simultaneous sequence of the second sub-circuit PWM signal and the third sub-circuit PWM signal is guaranteed, and therefore the duty ratio of the target PWM signal is determined by collecting rising edges of the second sub-circuit PWM signal and the third sub-circuit PWM signal, adjustment of the brightness of the backlight source is achieved, accuracy of the whole collection process is high, and display quality is guaranteed.
In the embodiment of the present invention, because the microcontroller 4 may only perform high-low level detection on the first path of PWM signal, in a specific implementation process, the microcontroller 4 may use a General Purpose Input/Output (GPIO) port to acquire the first path of PWM signal, and in addition, the microcontroller 4 may acquire the second sub-path of PWM signal and the third sub-path of PWM signal through a timer port, thereby ensuring the use performance of the dimming circuit.
In the embodiment of the present invention, before the first sub-circuit PWM signal, the second sub-circuit PWM signal, and the third sub-circuit PWM signal enter the microcontroller 4, each signal may be subjected to a pull-down process, so as to avoid interference of an abnormal signal on a detection result, and further ensure efficiency of backlight adjustment.
Based on the same inventive concept, as shown in fig. 6, an embodiment of the present invention further provides a display device, including:
a display panel 10;
the backlight module 20 comprises a backlight source 21 and a dimming circuit 22 of the backlight module for adjusting the brightness input to the backlight source 21.
The principle of the display device to solve the problem is similar to the dimming circuit 22 of the backlight module, so the implementation of the display device can refer to the implementation of the dimming circuit 22, and repeated descriptions are omitted.
In a specific implementation process, the display device provided in the embodiment of the present invention may be any product or component having a display function, such as a mobile phone, a tablet computer, a television, a display, a notebook computer, a digital photo frame, and a navigator. Other essential components of the display device are understood by those skilled in the art, and are not described herein nor should they be construed as limiting the present invention.
Based on the same inventive concept, as shown in fig. 7, an embodiment of the present invention further provides a dimming method using the dimming circuit of the backlight module, including:
s101: generating a target PWM signal through the driving board according to a current display picture;
s102: copying the target PWM signal into a first PWM signal, a second PWM signal and a third PWM signal through the clock generator, wherein the first PWM signal is directly input to the microcontroller, the second PWM signal is input to the microcontroller through a second sub-PWM signal modulated by a first gate circuit, and the third PWM signal is input to a third port of the controller through a third sub-PWM signal modulated by a second gate circuit, wherein the second sub-PWM signal and the third sub-PWM signal are in inverse symmetry;
s103: determining the high-low level state of the current PWM signal by the target PWM signal through the microcontroller, determining the edge jump time of the target PWM signal according to the second sub-PWM signal and the third sub-PWM signal, determining the duty ratio of the target PWM signal according to the high-low level state and the edge jump time, and adjusting the brightness output to the backlight source according to the duty ratio.
The specific implementation of steps S101 to S103 has been described in detail in the aforementioned dimming circuit of the backlight module, and is not repeated herein.
In the embodiment of the present invention, as shown in fig. 8, for the step in step S103: determining, by the microcontroller, the target PWM signal to determine a high-low level state of a current-path PWM signal, including:
s201: if the microcontroller detects that the first path of PWM signal is at a high level, the target PWM signal is determined to be at the high level;
s202: and determining that the target PWM signal is at a low level when the microcontroller detects that the first PWM signal is at a low level.
The specific implementation of steps S201 to S202 is already detailed in the dimming circuit of the backlight module, and is not described herein again.
In the embodiment of the present invention, as shown in fig. 9, the step in step S103 is: determining the duty ratio of the target PWM signal according to the high-low level state and the edge jumping time, including:
s301: if the target PWM signal is at a high level, respectively detecting a first moment of a rising edge of the second sub-circuit PWM signal, and after the first moment, a second moment of a rising edge of the third sub-circuit PWM signal, and determining a difference value between the second moment and the first moment as a first duration of the target PWM signal keeping the high level in a signal detection period;
s302: if the target PWM signal is at a low level, respectively detecting a third time of a rising edge of the third sub-PWM signal, and after the third time, a fourth time of a rising edge of the second sub-PWM signal, and determining a difference between the fourth time and the third time as a second duration of the target PWM signal maintaining the low level in the signal detection period;
s303: adding the first duration and the second duration to determine a total duration, wherein the total duration is a duration corresponding to the signal detection period;
s304: determining a ratio of the first duration to the total duration, the ratio being determined as a duty cycle of the target PWM signal during the signal detection period.
The specific implementation of steps S301 to S304 is already detailed in the dimming circuit of the backlight module, and is not repeated here.
In the embodiment of the present invention, in step S102: after the clock generator copies the target PWM signal into a first PWM signal, a second PWM signal, and a third PWM signal, if the microcontroller does not detect a rising edge of any PWM signal of the second sub-PWM signal and the third sub-PWM signal, the method further includes:
keeping the duty cycle of the target PWM signal unchanged by the microcontroller.
In the embodiment of the present invention, in step S102: after the clock generator copies the target PWM signal into a first PWM signal, a second PWM signal, and a third PWM signal, if the microcontroller does not detect a rising edge of the second sub-PWM signal and a rising edge of the third sub-PWM signal, the method further includes:
if the target PWM signal is at a high level, controlling the duty ratio of the target PWM signal to be a preset maximum value through the microcontroller, and adjusting the brightness of the backlight source to be a maximum brightness value according to the preset maximum value;
and if the target PWM signal is at a low level, controlling the duty ratio of the target PWM signal to be a preset minimum value through the microcontroller, and adjusting the brightness of the backlight source to be the brightness minimum value according to the preset minimum value.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.
Claims (10)
1. A dimming circuit of a backlight module is characterized by comprising:
a driver board, a clock generator electrically connected to the driver board, a gate circuit electrically connected to the clock generator, and a microcontroller electrically connected to the gate circuit, the gate circuit including a first gate circuit and a second gate circuit, wherein:
the clock generator is used for copying a target PWM signal output by the driving board according to a current display picture into a first PWM signal, a second PWM signal and a third PWM signal, the first PWM signal is directly input to the microcontroller, the second PWM signal is input to the microcontroller through a second sub-circuit PWM signal modulated by the first gate circuit, the third PWM signal is input to the microcontroller through a third sub-circuit PWM signal modulated by the second gate circuit, and the second sub-circuit PWM signal and the third sub-circuit PWM signal are in reverse symmetry;
the microcontroller is configured to:
determining the high-low level state of the target PWM signal according to the first path of PWM signal, determining the edge jumping time of the target PWM signal according to the second sub-path PWM signal and the third sub-path PWM signal, determining the duty ratio of the target PWM signal according to the high-low level state and the edge jumping time, and adjusting the brightness output to the backlight source according to the duty ratio.
2. The circuit of claim 1, wherein the microcontroller is specifically configured to:
if the first path of PWM signal is detected to be high level, determining that the target PWM signal is high level;
and if the first path of PWM signal is detected to be at a low level, determining that the target PWM signal is at a low level.
3. The circuit of claim 2, wherein if the target PWM signal is high, the microcontroller is specifically configured to:
respectively detecting a first moment of a rising edge of the second sub-circuit PWM signal, and after the first moment, a second moment of a rising edge of the third sub-circuit PWM signal, and determining a difference value between the second moment and the first moment as a first duration of the target PWM signal keeping the high level in one signal detection period;
if the target PWM signal is at a low level, respectively detecting a third time of a rising edge of the third sub-PWM signal, and after the third time, a fourth time of a rising edge of the second sub-PWM signal, and determining a difference between the fourth time and the third time as a second duration of the target PWM signal maintaining the low level in the signal detection period;
adding the first duration and the second duration to determine a total duration, wherein the total duration is a duration corresponding to the signal detection period;
determining a ratio of the first duration to the total duration, the ratio being determined as a duty cycle of the target PWM signal during the signal detection period.
4. The circuit of claim 2, wherein if the microcontroller does not detect a rising edge of either of the second sub-circuit PWM signal and the third sub-circuit PWM signal, the microcontroller is specifically configured to:
keeping the duty ratio of the target PWM signal unchanged.
5. The circuit of claim 2, wherein if the microcontroller does not detect a rising edge of the second sub-circuit PWM signal and a rising edge of the third sub-circuit PWM signal, the microcontroller is specifically configured to:
if the target PWM signal is at a high level, controlling the duty ratio of the target PWM signal to be a preset maximum value, and adjusting the brightness of the backlight source to be a brightness maximum value according to the preset maximum value;
and if the target PWM signal is at a low level, controlling the duty ratio of the target PWM signal to be a preset minimum value, and adjusting the brightness of the backlight source to be a brightness minimum value according to the preset minimum value.
6. The circuit of claim 1, wherein the first gate circuit is an and gate, a first input of the and gate is electrically connected to the output of the clock generator, a second input of the and gate is electrically connected to the first predetermined high potential terminal, and an output of the and gate is electrically connected to the first port of the microcontroller.
7. The circuit of claim 1, wherein the second gate circuit is a nand gate, a third input of the nand gate is electrically connected to the output of the clock generator, a fourth input of the nand gate is electrically connected to the second predetermined high potential terminal, and an output of the nand gate is electrically connected to the second port of the microcontroller.
8. A display device, comprising:
a display panel;
a backlight module comprising a backlight source and a dimming circuit of the backlight module as claimed in any one of claims 1 to 7 for adjusting the brightness input to the backlight source.
9. A dimming method using the dimming circuit of the backlight module according to any one of claims 1 to 7, comprising:
generating a target PWM signal through the driving board according to a current display picture;
copying the target PWM signal into a first PWM signal, a second PWM signal and a third PWM signal through the clock generator, wherein the first PWM signal is directly input to the microcontroller, the second PWM signal is input to the microcontroller through a second sub-PWM signal modulated by a first gate circuit, and the third PWM signal is input to a third port of the controller through a third sub-PWM signal modulated by a second gate circuit, wherein the second sub-PWM signal and the third sub-PWM signal are in inverse symmetry;
determining the high-low level state of the current PWM signal by the target PWM signal through the microcontroller, determining the edge jump time of the target PWM signal according to the second sub-PWM signal and the third sub-PWM signal, determining the duty ratio of the target PWM signal according to the high-low level state and the edge jump time, and adjusting the brightness output to the backlight source according to the duty ratio.
10. The method of claim 9, wherein said determining the target PWM signal by the microcontroller determines a high-low state of a current PWM signal, comprising:
if the microcontroller detects that the first path of PWM signal is at a high level, the target PWM signal is determined to be at the high level;
and determining that the target PWM signal is at a low level when the microcontroller detects that the first PWM signal is at a low level.
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