CN113450704B - LED driving method, driving unit, display device and readable storage medium - Google Patents
LED driving method, driving unit, display device and readable storage medium Download PDFInfo
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- CN113450704B CN113450704B CN202011089130.9A CN202011089130A CN113450704B CN 113450704 B CN113450704 B CN 113450704B CN 202011089130 A CN202011089130 A CN 202011089130A CN 113450704 B CN113450704 B CN 113450704B
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- 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
- G09G3/22—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 using controlled light sources
- G09G3/30—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 using controlled light sources using electroluminescent panels
- G09G3/32—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 using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
Abstract
The invention relates to an LED driving method, a driving unit, a display device and a readable storage medium. The LED driving method comprises the following steps: acquiring a previous frame of the LED light-emitting device which needs to be driven currently and the gray value of the frame; determining an output parameter of the current signal according to the gray values of the previous frame and the current frame; the output parameters of the current signal comprise the current segment number and the current output time of each segment, the current segment number is not less than 2, the current output time of each segment is one N of the period of the global clock signal of the LED driving circuit, and N is an integer not less than 2; and in the period of starting the scanning signal, outputting a current signal according to the output parameter of the current signal so as to drive the LED light-emitting device which needs to be driven currently. The LED display refresh rate under low gray scale is improved by driving with the current signals of multiple sections of short time, and the display effect of the LED can be improved in some implementation processes.
Description
Technical Field
The present invention relates to the field of LED (Light Emitting Diode) display, and in particular, to an LED driving method, a driving unit, a display device, and a readable storage medium.
Background
With the development of small spacing, the LED display screen puts higher requirements on line driving, and the line driving is switched from a pure P-type Field Effect Transistor (P-channel Metal-Oxide-Semiconductor Field-Effect Transistor, PMOSFET) to multifunctional line driving with higher integration level and stronger function. In the related art, a Pulse-Width Modulation (PWM) is used to output a current signal, and different current signal Pulse widths represent different gray levels displayed by an LED, wherein a high gray level requires a wider current signal Pulse Width, and a low gray level corresponds to a narrower current signal Pulse Width. In the related art, a break-up function is used to improve the refresh rate of the LED display. However, in the related art, the refresh rate of the low gradation is still low, and the display effect of the low gradation tends to be less than expected.
Therefore, how to increase the refresh rate of the LED display panel when displaying low gray scale and ensure the display effect of low gray scale is an urgent problem to be solved.
Disclosure of Invention
In view of the above-mentioned shortcomings of the related art, the present application aims to provide a method and a device for driving an LED, a display device and a readable storage medium, which are intended to solve the problems of low refresh rate and poor display effect of low gray scales when an LED display panel displays low gray scales.
An LED driving method comprising:
acquiring a previous frame of the LED light-emitting device which needs to be driven currently and the gray value of the frame;
determining an output parameter of the current signal according to the gray values of the previous frame and the current frame;
the output parameters of the current signal comprise the number of current segments and the current output time of each segment, wherein the number of the current segments is not less than 2, the current output time is one N of the period of a global clock signal of the LED driving circuit, and N is an integer not less than 2;
and outputting the current signal according to the output parameter of the current signal to drive the LED light-emitting device which needs to be driven currently in the period of one-time scanning signal starting.
According to the LED driving method, the gray values of the previous frame and the current frame of the LED light-emitting device needing to be driven currently are obtained, and the output parameters of the current signal are determined according to the gray values of the previous frame and the current frame, wherein the output parameters of the current signal comprise the current segment number and the current output time of each segment, the current segment number is not less than 2, the current output time is one N-th of the period of a global clock signal of the LED driving circuit, N is an integer not less than 2, and in the starting period of a scanning signal, the current signal is output according to the output parameters of the current signal to drive the LED light-emitting device needing to be driven currently; the current signals output by the LED driving method are multi-section current signals with the current output time being shorter than the period of the global clock signal of the LED driving circuit, and the refresh rate of LED display low gray scale is improved. And because the total duration time of the current signals output in multiple sections is longer than the duration time of only one section of current signals, the total duration time of the current signals is increased, the influence of parasitic capacitance on the current value is weakened, and the LED display quality under low gray scale can be improved in some implementation processes.
Optionally, before determining the output parameter of the current signal according to the gray-level values of the previous frame and the current frame, the method further includes:
and judging whether the gray value of the current frame is lower than a preset threshold value, if not, switching to a high gray driving method to control the LED driving circuit.
By setting a preset threshold value, the driving method is ensured to be suitable for the current display condition.
Optionally, the determining the output parameter of the current signal according to the gray-level values of the previous frame and the current frame includes:
and acquiring the output parameter of the current signal from a mapping table stored in the LED driving circuit according to the gray value of the last frame and the gray value of the current frame of the LED light-emitting device needing to be driven.
By obtaining the output parameters of the current signal from the stored mapping table, the output parameters of the current signal can be quickly obtained for control.
Optionally, the current output time of each segment is the same during the period of one-time scanning signal starting.
By setting the current output time of each segment to be the same, in some implementations, control can be simplified.
Optionally, during a period when the scanning signal is turned on, providing the current signal according to the output parameter of the current signal includes:
and continuously outputting M current signals within the starting period of one scanning signal, wherein M is equal to the number of the current segments, and the duration of each current signal is equal to the corresponding current output time.
Optionally, during a period when the scanning signal is turned on, providing the current signal according to the output parameter of the current signal includes:
outputting M current signals within the period of one-time scanning signal starting, wherein M is equal to the number of the current segments, the duration of each current signal is equal to the corresponding current output time, the interval time from the current signal starting to the current signal starting at the next time is equal, and the interval time between the current signal starting at the last time and the scanning signal starting is less than the interval time between the current signals starting at two adjacent times.
The uniformity of the LED display can be further improved by uniformly distributing the M current signals in the turn-on period of one scanning signal.
Optionally, before providing the current signal according to the output parameter of the current signal, the method further includes:
and performing frequency multiplication processing on the global clock signal to obtain a current clock signal, wherein the current clock signal is used as a clock reference of the current signal.
The global clock signal of the LED driving circuit is multiplied, so that a current clock signal with higher frequency is provided for controlling the current signal.
Based on the same inventive concept, the application also provides an LED driving unit, which comprises a processor, a memory and a communication bus;
the communication bus is used for realizing connection communication between the processor and the memory;
the processor is configured to execute one or more computer programs stored in the memory to implement the steps of the LED driving method as described above.
The current signals output by the LED driving unit are multi-section current signals with current output time shorter than the period of the global clock signal of the LED driving circuit, and the refresh rate of LED display low gray scale is improved. And because the total duration time of the current signals output in multiple sections is longer than the duration time of only one section of current signals, the total duration time of the current signals is increased, the influence of parasitic capacitance on the current value is weakened, and the LED display quality under low gray scale can be improved in some implementation processes.
Based on the same inventive concept, the application also provides a display device;
the display device includes: the LED driving circuit comprises an LED array, a plurality of row data lines, a plurality of column data lines and the LED driving unit;
each row of data lines electrically connects the first poles of the same row of LED light-emitting devices in the LED array;
each column data line electrically connects second poles of the same column of LED light-emitting devices in the LED array;
any one of the column data line and the row data line is electrically connected with the current signal output end of the LED driving unit to receive a current signal, and the other one of the column data line and the row data line receives a scanning signal.
The display device has high refresh rate for displaying low gray scale. The LED light-emitting device is controlled by the current signals output in multiple sections, and the total duration time of the current signals in multiple sections is longer than the duration time of only one current signal output, so that the total duration time of the current signals is increased, the influence of parasitic capacitance on the current value is weakened, the low gray scale display is uniform in some implementation processes, and the effect is good.
Optionally, the LED driving unit includes:
the voltage output unit is connected with the column data line, receives the global clock signal and controls the column data line based on the global clock signal;
a current control unit for controlling the column data line based on a clock signal having a frequency higher than the global clock signal;
and the current output unit is connected with the column data line and outputs a current signal when the voltage output unit and the current control unit both provide output signals.
The current control unit is arranged to be matched with the voltage output unit for control, and the implementation mode is simple and reliable.
Optionally, the current control unit includes:
a frequency multiplier to receive and multiply the global clock signal;
and the time schedule controller is used for receiving the clock signal obtained by frequency multiplication of the frequency multiplier and controlling the column data line based on the clock signal after frequency multiplication.
The clock signal with higher frequency is obtained through the frequency multiplier, the operation is simple, and the cost is low.
Based on the same inventive concept, the present application also provides a readable storage medium storing one or more programs, which are executable by one or more processors to implement the steps of the LED driving method as described above.
Drawings
Fig. 1 is a flowchart of an LED driving method according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a current signal with a part of gray-scale values in the related art according to an embodiment of the invention;
FIG. 3 is a timing diagram of a current signal according to the present invention;
FIG. 4 is another timing diagram of the current signals according to the present invention;
fig. 5 is a schematic structural diagram of an LED driving unit 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 schematic diagram of a related art LED driving circuit according to another embodiment of the present invention;
fig. 8 is a schematic diagram of an LED driving circuit according to another embodiment of the present invention;
fig. 9 is a flowchart illustrating a method for driving an LED according to another embodiment of the present invention;
fig. 10 is a schematic diagram of an implementation manner of a control portion of an LED driving circuit according to another embodiment of the present invention;
FIG. 11 is a timing diagram of a global clock signal and a current clock signal according to another embodiment of the present invention;
FIG. 12 is a timing diagram illustrating a control process performed by the LED driving circuit shown in FIG. 10 according to another embodiment of the present invention;
fig. 13 is a timing diagram illustrating another control performed by the LED driving circuit shown in fig. 10 according to another embodiment of the present invention;
fig. 14 is a schematic diagram of another implementation manner of a control portion of an LED driving circuit according to another embodiment of the present invention;
FIG. 15 is a timing diagram illustrating a control process performed by the LED driving circuit shown in FIG. 14 according to another embodiment of the present invention;
description of reference numerals:
t1 — on period of one scan signal; t2 — period of global clock signal; t3 — one cycle of the clock signal of the current signal; 50-an LED driving unit; 51-a processor; 52-a memory; 53-a communication bus; 61-row data lines; 62-column data line; 71-a voltage output unit; 72-a current output unit; 73-a current control unit; 731-frequency multiplier; 732-timing controller.
Detailed Description
To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present application are given in the accompanying drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
In the related art, the LED display panel has a low refresh rate when displaying low gray scale, and the effect is not good.
Based on this, the present application intends to provide a solution to the above technical problem, the details of which will be explained in the following embodiments.
Example (b):
referring to fig. 1, fig. 1 is a flowchart of an LED driving method according to an embodiment of the present invention,
s101, acquiring a previous frame of the LED light-emitting device which needs to be driven currently and the gray value of the frame;
it should be noted that the LED display screen driven by the LED driving method of the present invention is a scanning display, in which the time between two displays is short because the LED light emitting device flashes quickly, so that the gray scale displayed in the previous frame affects the next frame. That is, the LED light emitting device needs to calculate the gray scale value of the previous frame and the gray scale value of the current frame, and then determine how to drive the LED light emitting device to achieve the effect of displaying the gray scale required by the current frame. In this embodiment, the gray values of the previous frame and the current frame of the LED light emitting device that needs to be driven are obtained, it should be understood that, in the current LED light emitting device that needs to be driven, that is, in the scanning display, the LED light emitting device that the corresponding scanning signal turns on, taking line scanning as an example, when the scanning signal of a certain line turns on, the LED light emitting device of the corresponding line may be driven, and according to the content that needs to be displayed and the content that has been displayed, it can be known whether the LED light emitting devices need to be driven, and the gray values of the previous frame and the current frame are obtained. It can be understood that the previous frame of the LED light emitting device that needs to be driven currently and the gray scale value of the current frame can be obtained through a corresponding control portion, such as a control chip.
S102, determining an output parameter of the current signal according to the gray values of the previous frame and the current frame;
the LED light-emitting device is a component driven by current to work, and can show different display effects by controlling a current signal; for example, if the current signal is continued for a long time, the LED light emitting device emits light for a long time, thereby exhibiting a high gray scale display effect. In this embodiment, the output parameter of the current signal is determined according to the gray-scale value of the previous frame and the gray-scale value of the present frame, and it should be noted that the determined output parameter of the current signal indicates how the LED light emitting device should be driven if the current signal is to be converted from the gray-scale value of the previous frame to the gray-scale value of the present frame.
In the present embodiment, the output parameters of the current signal include the number of current segments and the current output time of each segment, the number of current segments is not less than 2, and the current output time of each segment is one nth of the period of the global clock signal of the LED driving circuit, N being an integer not less than 2.
It will be appreciated that the global clock signal serves as a clock reference for various types of control in the LED driver circuit. It should be noted that, in the related art, as shown in fig. 2, in the on period T1 of the primary scan signal, the on period T1 of the primary scan signal in the present embodiment lasts 32 × 512 scan signal periods, the on period T1 of the primary scan signal is divided into 32 segments, and for the display of the low gray scale of 32 gray scale values or less, each segment is driven by at most one segment of current signal (the low level in the figure indicates the output current signal), and the 32 gray scale value has one segment of current signal in the on period T1 of each scan signal. For the display of the lower gray scale above 32 gray scale values, there may be no less than two segments of current signals in the turn-on period of one scan signal, but the current signals are controlled based on the global clock signal, the duration of each segment of current signal is at least the period T2 of the global clock signal, and the duration of each segment of current signal is kept at the maximum at the highest gray scale value.
In this embodiment, the current output time of each segment is controlled to be N times of the period of the global clock signal of the LED driving circuit, so that more segments of current signals can exist in the on period of one scanning signal, and at least two segments of current signals exist even when the gray scale value is 1.
It should be noted that, in the LED display circuit, mutual capacitance, that is, parasitic capacitance exists on the data line of the LED light emitting device due to the wiring of the circuit. The parasitic capacitance may divide a part of the current to some extent, which may cause the current value of the LED to be lower than an ideal current value in a short time, resulting in insufficient luminance/chromaticity display uniformity. Particularly in the case of low gray scale display, since the duration of the current signal required for the low gray scale display itself is short, the influence of the parasitic capacitance on the formation thereof is more significant, and the current value may be lower than the ideal current value before the parasitic capacitance is filled. In this embodiment, the current signal is divided into at least 2 segments, and the current output time is one N times of the period of the global clock signal of the LED driving circuit, and since the current signal is divided into multiple segments to be output, the total duration of the current signals output in multiple segments is longer than the duration of only one segment of the current signal output in the same turn-on period of the scanning signal under the condition that the same gray scale value is ensured to be displayed. It will be appreciated that the time for which the parasitic capacitance charges is substantially constant, i.e. the time for which the parasitic capacitance has an effect on the current value is substantially fixed, and the effect of the parasitic capacitance on the current value is relatively attenuated as the total duration of the current signal increases.
In some embodiments, before determining the output parameter of the current signal according to the gray-level values of the previous frame and the present frame, the method further includes: and judging whether the gray value of the frame is lower than a preset threshold value, if not, switching to a high gray driving method to control the LED driving circuit.
It can be understood that, in the LED driving method of the present embodiment, the current signal not less than 2 segments is used for driving, so that a better display effect can be achieved in the low gray level display, and the refresh rate in the low gray level display can be improved. However, for the display with higher gray scale, the driving method of the LED of the present embodiment does not improve the display effect as much as the low gray scale. And the display of high gray scale value needs to occupy longer duration of the current signal in one scanning start-up period, and the current signal cannot be divided into multiple current signals with duration less than half of the period of the global clock signal and less than half of the period of the global clock signal. And when the gray value of the frame is greater than the preset threshold value, switching to a high gray driving method to control the LED driving circuit. It is to be understood that the high gray driving method referred to herein may be any driving method capable of displaying high gray. The preset threshold may be a value obtained after a technician tests, and the LED driving method of this embodiment may be used for displaying gray-scale values lower than the preset threshold, for example, 32 gray-scale values, 64 gray-scale values, 256 gray-scale values, and the like may be used as the preset threshold.
As an example, the following manner may be adopted as the high gradation driving method: determining output parameters of a current signal according to the gray values of the previous frame and the current frame, wherein the output parameters of the current signal comprise the number of current segments and the current output time of each segment, and the number of the current segments is equal to 1; and outputting the current signal according to the output parameter of the current signal to drive the LED light-emitting device which needs to be driven currently in the period of one-time scanning signal starting. That is, for the display of a high gradation value, the current signal satisfying the current output time can be directly output in a non-segmented manner.
In some embodiments, determining the output parameter of the current signal according to the gray-level values of the previous frame and the current frame includes:
and acquiring the output parameter of the current signal from a mapping table stored in the LED driving circuit according to the gray value of the last frame and the gray value of the current frame of the LED light-emitting device required to be driven.
The output parameters of the current signals are stored in the LED driving circuit in the form of a mapping table, and when a corresponding processor carries out driving control, the output parameters of the current signals can be directly obtained only by inquiring according to the gray values of the previous frame and the current frame, so that the gray values displayed by the LED light-emitting devices can be equal to the gray values of the current frame through the inquired output parameters of the current signals.
As shown in table 1, taking 2bits gray as an example, for example, the output parameter of the current signal represented by the parameter XX in the table represents that the gray displayed in the previous frame is gray value 2, and the gray displayed in the current frame is gray value 3, the corresponding output parameter of the current signal should be the parameter 32. It should be noted that the mapping relationship stored in the mapping table is obtained by testing of a technician, and the technician tests an appropriate output parameter of the current signal according to actual conditions and according to various conditions of the gray-scale values of the previous frame and the current frame, stores the output parameter in the LED driving circuit, and can directly call the output parameter when a corresponding processor performs driving control. It is understood that there may be a plurality of suitable output parameters of the current signal for the same gray-level value of the previous frame and the present frame, and the output parameters may be arbitrarily selected. In other embodiments, the output parameter of the current signal may be stored in other manners.
TABLE 1
In some embodiments, the current output time of each segment is the same during one scan signal turn-on period.
It can be understood that, when the current output time of each segment is the same, the number of current segments in the output parameters of the current signals of different gray scale values is different, and the number of current segments of a low gray scale value is smaller than that of current segments of a higher gray scale value. In some implementation scenes, the current output time of each section is set to be the same, so that the control can be facilitated, and parameters needing to be managed in the control process are reduced.
And S103, outputting a current signal according to the output parameter of the current signal in the starting period of the primary scanning signal so as to drive the LED light-emitting device which needs to be driven currently.
In some embodiments, providing the current signal according to the output parameter of the current signal during the one-time scan signal on period includes:
and continuously outputting M current signals within the starting period of one scanning signal, wherein M is equal to the number of current segments, and the duration of each current signal is equal to the corresponding current output time.
Fig. 3 is a timing diagram illustrating the provision of a current signal according to an output parameter of the current signal, as shown in fig. 3. Taking 4 current signals as an example, the 4 current signals are output continuously, that is, the time interval from each turn-on of the current signal to the next turn-on of the current signal is the shortest possible time interval. It will be appreciated that the shortest interval between two current signals is equal to one period T3 of the clock signal controlling the current signals.
In some embodiments, providing the current signal according to the output parameter of the current signal during the one-time scan signal on period includes:
outputting M current signals within the period of one-time scanning signal starting, wherein M is equal to the number of the current segments, the duration of each current signal is equal to the corresponding current output time, the interval time from the current signal starting to the current signal starting at the next time is equal, and the interval time between the current signal starting at the last time and the scanning signal starting is less than the interval time between the current signals starting at two adjacent times. In such an embodiment, the current signals corresponding to M times are distributed more uniformly in the on period of one scanning signal.
As shown in fig. 4, also taking the 4 current signals as an example, the 4 current signals are more uniformly distributed in the on period of one scanning signal. It is understood that the respective durations of the M current signals may be different. In the specific implementation process, for the same gray scale value, different current signal output modes may also need different current signal output parameters to achieve the effect of displaying the same gray scale value, and in each case, how to set the current signal output parameters can be measured in advance by a technician. It can be understood that, if the current signal is uniformly distributed and outputted within one scanning signal on period, the uniformity of the LED display can be further improved.
In some embodiments, providing the current signal according to the output parameter of the current signal further comprises:
and carrying out frequency multiplication processing on the global clock signal to obtain a current clock signal, wherein the current clock signal is used as a clock reference of the clock signal.
It will be appreciated that the current output time of the current signal is one-N times the period of the global clock signal of the LED driver circuit, and thus the current signal requires a higher frequency clock signal as a reference. In some embodiments, the global clock signal used by the LED driving circuit may be directly subjected to frequency multiplication to obtain a higher frequency clock signal as a clock reference of the current signal. Illustratively, the global clock signal can be frequency-doubled by a circuit, a chip, a single chip and the like with a frequency doubling function.
In other embodiments, other clock signals with higher frequency may also be directly accessed as the clock signal of the current signal, and it should be noted that the frequency of the clock signal of the current signal should be a multiple of the frequency of the clock signal of the current signal.
The present embodiment further provides an LED driving unit 50, see fig. 5, including a processor 51, a memory 52, and a communication bus 53, where the communication bus 53 is used to implement connection communication between the processor 51 and the memory 52;
the processor 51 is configured to execute one or more programs stored in the memory 52 to implement the steps of the LED driving method as described above. It is understood that the processor 51 may be one or more, and a plurality of processors may respectively execute the steps of collectively implementing the LED driving method as described above.
The present embodiment further provides a display device, referring to fig. 6, including an LED array, a plurality of row data lines 61, a plurality of column data lines 62, and the LED driving unit 50 as described above;
each row of data lines 61 electrically connects first poles of the same row of LED light emitting devices in the LED array;
each column data line 62 electrically connects second poles of the same column of LED light emitting devices in the LED array;
the LED driving unit 50 is used for providing a current signal to drive the diode array;
either one of the row data line 61 and the column data line 62 is electrically connected to a current signal output terminal of the LED driving unit 50 to receive a current signal, and the other one receives a scan signal.
In this embodiment, the first electrode of the LED light emitting device is an anode, and the second electrode is a cathode. For an LED light emitting device, the row data line and the column data line are connected to the anode and the cathode, respectively, in other embodiments, the anode may be connected to the column data line, and the cathode may be connected to the row data line. According to different circuit connection modes, the current signal output by the LED driving unit can be positive or negative. When the display device is displaying, the scanning signals are used for scanning the row data lines or the column data lines one by one, the scanning signals are used for scanning the row data lines, generally called as row scanning display, the current signal output end of the LED driving unit is connected with each column data line, and when the scanning signals are scanned to the corresponding row data lines, the current signals are provided for the column data lines to drive the corresponding LED light-emitting devices. In this embodiment, the scan signal may also be provided by the LED driving unit.
The present embodiments also provide a readable storage medium that includes volatile or non-volatile, removable or non-removable media implemented in any method or technology for storage of information such as readable instructions, data structures, program modules or other data. Readable storage media include, but are not limited to, RAM (Random Access Memory), ROM (Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), flash Memory or other Memory technology, CD-ROM (Compact Disc Read-Only Memory), DVD (Digital versatile Disc) or other optical Disc storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by a processor.
The readable storage medium in this embodiment stores one or more programs, and the one or more programs are executable by one or more processors to implement the steps of the LED driving method as described above.
In the LED driving method provided in this embodiment, the gray values of the previous frame and the current frame of the LED light emitting device to be currently driven are obtained, and the output parameter of the current signal is determined according to the gray values of the previous frame and the current frame, where the output parameter of the current signal includes the number of current segments and the current output time of each segment, the number of current segments is not less than 2, the current output time is one nth of the period of the global clock signal of the LED driving circuit, N is an integer not less than 2, and during the turn-on period of a scanning signal, the current signal is output according to the output parameter of the current signal to drive the LED light emitting device to be currently driven; the current signal is split into a plurality of sections of current signals of which the current output time is shorter than the period of the global clock signal of the LED driving circuit, and the refresh rate of LED display low gray scale is improved. And because the total duration time of the current signals output in multiple sections is longer than the duration time of only one section of current signals, the total duration time of the current signals is increased, the influence of parasitic capacitance on the current value is weakened, and the LED display quality under low gray scale can be improved in some implementation processes.
Another embodiment of the present invention
The present embodiment further describes the LED driving method according to the present invention with reference to specific circuits and timing sequences and specific control processes. Fig. 7 is a schematic diagram of an LED driving circuit in the related art, which illustrates a specific implementation of a part of functions in an LED driving unit, and includes a voltage output unit 71 and a current output unit 72, where the voltage output unit 71 can be controlled according to a corresponding program to provide an output signal, and the current output unit 72 outputs a current signal when the output signal is turned on. Referring to fig. 8 again, for the illustration of the LED driving circuit provided in the present embodiment, the LED driving unit in the present embodiment includes a voltage output unit 71, a current output unit 72, and a current control unit 73, wherein the voltage output unit 71 and the current output unit 72 use a global clock signal as a clock reference, and the current control unit 73 uses a clock signal with a higher frequency as a reference. The voltage output unit is connected with the column data line, receives the global clock signal and controls the column data line based on the global clock signal, and the current control unit is used for controlling the column data line based on the clock signal with the frequency higher than that of the global clock signal; and the current output unit is connected with the column data line and outputs a current signal when the voltage output unit and the current control unit provide output signals. It should be noted that, in this embodiment, the processor, the memory or the communication bus of the LED driving unit is not directly shown, and in practical applications, all or part of the LED driving unit may be distributed in each of the units, or may be formed as a single part or multiple parts to control the units. In the present embodiment, a current control unit 73 is added on the basis of the related art, and the current control unit 73 uses a clock signal with a higher frequency to determine whether the current of the current output unit 72 is output together with the voltage output unit 71. It should be understood that in other embodiments, other circuit structures or functional modules may be used to implement the LED driving method of the present invention.
As shown in fig. 9, the LED driving circuit of the present embodiment performs the following steps:
s201, acquiring a global clock signal of the LED driving circuit, and performing frequency multiplication processing on the global clock signal to obtain a current clock signal as a clock reference of the current signal;
for example, as shown in fig. 10, in this embodiment, the current control unit 73 may include a frequency multiplier 731 and a timing controller 732, the frequency multiplier 731 is connected to a global clock signal of the LED driving circuit to perform frequency multiplication processing on the global clock signal, the timing controller 732 controls according to the frequency-multiplied current clock signal output by the frequency multiplier, and for example, the timing controller 732 may control on/off of the column data line to achieve an effect of controlling whether the current output unit can output the current signal. Fig. 11 shows timing diagrams of the global clock signal and the current clock signal, and in this embodiment, the frequency of the current clock signal is 3 times the frequency of the global clock signal. In other embodiments, a current clock signal with a frequency higher than the global clock signal may be directly accessed without using a frequency multiplier.
S202, acquiring a previous frame of the LED light-emitting device which needs to be driven currently and the gray value of the frame;
the LED light emitting device displays the content to be displayed frame by frame.
S203, judging whether the gray value of the frame is lower than a preset threshold value, if not, executing S204, and if so, executing S205;
the LED driving method of the present embodiment is suitable for low gray scale display, and the preset threshold in the present embodiment is 32 gray scale values as an example.
S204, controlling the LED driving circuit by using a high gray scale driving method;
s205, acquiring the output parameter of the current signal from a mapping table stored in the LED driving circuit according to the gray value of the last frame and the gray value of the current frame of the LED light-emitting device needing to be driven;
in this embodiment, a corresponding mapping table is set for the gray values of 32 gray values and below, and the query is performed from the mapping table according to the gray values of the previous frame and the current frame. The output parameters of the current signals stored in the mapping table can be obtained by technicians through tests. In practical application, for the same control effect (i.e. changing from the same previous frame gray value to the same present frame gray value), a plurality of different output parameters of the current signal can be preset, so as to ensure richer control strategies and adapt to more requirements.
S206, continuously outputting a current signal in the starting period of the primary scanning signal;
taking the current segment number as 4 segments and the current output time of each segment being one period of the current clock signal as an example, please refer to fig. 12, which is a timing diagram of the implementation process, wherein the voltage output unit provides the output signal (OUT signal in the figure), the current control unit provides the control signal (CTL signal in the figure), and when the output signal and the control signal are both turned on, the current output unit provides the current signal. The output signal of the voltage output unit of the embodiment adopts a global clock signal as a reference, and the starting time can be set to be longer; and the control signal of the current output unit is subjected to frequency multiplication to obtain a current clock signal, and the current clock signal is controlled together with the voltage output unit. As shown in fig. 13, the output signal is also divided into a plurality of segments to be turned on, and the control signal is turned on according to the output reference of the current signal during the turn-on period of the output signal. However, it should be understood that the output signal and the control signal are both turned on during one scan signal. In this embodiment, the signal is on when it is at low level, but in other embodiments, a control scheme that is active at high level may be used, that is, the signal is on when it is at high level.
It should be noted that any control method may be adopted as long as the current signal provided by the final current output unit is consistent with the output parameter of the current signal acquired in step S205. The LED driving circuit and the control portion are only used as an example of one implementation, and the present invention is not limited to a specific structure of hardware. Still another example is provided, as shown in fig. 14, a current clock signal can be obtained by directly providing a frequency multiplication to the voltage output unit 71, in this example, only one unit is used to control the output of the current, and the timing sequence thereof is shown in fig. 15, which saves one control signal and is simpler in circuit structure and timing control compared to fig. 12 under the same control effect.
It should be noted that the timing and output parameters of the current signal provided in the present embodiment are only schematic illustrations for explaining the LED driving method of the present invention, and do not represent actual control parameters. In practical applications, the output parameters of the current signals need to be obtained by a technician according to the required display effect, and the specific time sequence may be presented differently according to the actual situation.
The LED driving method of this embodiment obtains the gray values of the previous frame and the current frame of the LED light emitting device that needs to be driven currently, and uses the high gray driving method to control when the gray value of the current frame is higher than the preset threshold, and determines the output parameter of the current signal according to the gray values of the previous frame and the current frame when the gray value of the current frame is lower than the preset threshold, and the current signal output according to the output parameter of the current signal is a multi-segment current signal with a shorter duration of each segment, compared with a single-segment current signal with a low gray in the conventional control method, the LED driving method of this embodiment improves the refresh rate of the LED low gray display, and the total duration of the multi-segment output current signal is longer than the duration of only outputting one segment of current signal, so that the total duration of the current signal is increased, and the influence of the parasitic capacitance on the current value is relatively weakened, the quality of LED display under the low gray is promoted.
It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.
Claims (12)
1. An LED driving method, comprising:
acquiring a previous frame of the LED light-emitting device which needs to be driven currently and the gray value of the frame;
determining an output parameter of the current signal according to the gray values of the previous frame and the current frame;
the output parameters of the current signal comprise the number of current segments and the current output time of each segment, wherein the number of the current segments is not less than 2, the current output time of each segment is one N of the period of a global clock signal of the LED driving circuit, and N is an integer not less than 2;
and outputting the current signal according to the output parameter of the current signal to drive the LED light-emitting device which needs to be driven currently in the starting period of the scanning signal, wherein a clock signal with the frequency higher than that of the global clock signal is used as the clock reference of the current signal.
2. The LED driving method according to claim 1, before determining the output parameter of the current signal according to the gray-level values of the previous frame and the current frame, further comprising:
and judging whether the gray value of the current frame is lower than a preset threshold value, if not, switching to a high gray driving method to control the LED driving circuit.
3. The LED driving method according to claim 1, wherein the determining the output parameter of the current signal according to the gray-level values of the previous frame and the current frame comprises:
and acquiring the output parameter of the current signal from a mapping table stored in the LED driving circuit according to the gray value of the last frame and the gray value of the current frame of the LED light-emitting device needing to be driven.
4. The LED driving method of claim 1, wherein the current output time of each segment is the same during one scan signal turn-on period.
5. The LED driving method according to claim 1, wherein providing a current signal according to an output parameter of the current signal during a period in which a scan signal is turned on comprises:
and continuously outputting M current signals within the starting period of one scanning signal, wherein M is equal to the number of the current segments, and the duration of each current signal is equal to the corresponding current output time.
6. The LED driving method according to claim 1, wherein providing a current signal according to an output parameter of the current signal during a period in which a scan signal is turned on comprises:
outputting M current signals within the period of one-time scanning signal starting, wherein M is equal to the number of the current segments, the duration of each current signal is equal to the corresponding current output time, the interval time from the current signal starting to the current signal starting at the next time is equal, and the interval time between the current signal starting at the last time and the scanning signal starting is less than the interval time between the current signals starting at two adjacent times.
7. The LED driving method according to any one of claims 1 to 6, wherein before providing a current signal according to an output parameter of the current signal, further comprising:
and performing frequency multiplication processing on the global clock signal to obtain a current clock signal, wherein the current clock signal is used as a clock reference of the current signal.
8. The LED driving unit is characterized by comprising a processor, a memory and a communication bus, wherein the communication bus is used for realizing connection communication between the processor and the memory;
the processor is configured to execute one or more programs stored in the memory to implement the steps of the LED driving method according to any one of claims 1 to 7.
9. A display device comprising an LED array, a plurality of row data lines, a plurality of column data lines, and the LED driving unit of claim 8;
each row of data lines electrically connects the first poles of the same row of LED light-emitting devices in the LED array;
each column data line electrically connects second poles of the same column of LED light-emitting devices in the LED array;
any one of the column data line and the row data line is electrically connected with the current signal output end of the LED driving unit to receive a current signal, and the other one of the column data line and the row data line receives a scanning signal.
10. The display device according to claim 9, wherein the LED driving unit includes:
the voltage output unit is connected with the column data line, receives the global clock signal and controls the column data line based on the global clock signal;
a current control unit for controlling the column data line based on a clock signal having a frequency higher than the global clock signal;
and the current output unit is connected with the column data line and outputs a current signal when the voltage output unit and the current control unit both provide output signals.
11. The display device according to claim 10, wherein the current control unit includes:
a frequency multiplier to receive and multiply the global clock signal;
and the time schedule controller is used for receiving the clock signal obtained by frequency multiplication of the frequency multiplier and controlling the column data line based on the clock signal after frequency multiplication.
12. A readable storage medium storing one or more programs, the one or more programs being executable by one or more processors to implement the steps of the LED driving method according to any one of claims 1 to 7.
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