Backlight driving method, driving chip and backlight module

Abstract

The invention provides a backlight driving method, a driving chip and a backlight module, and the method comprises the steps: for an LED in the backlight module, determining a target gray-scale value of a pixel point corresponding to the LED in a process of displaying a current frame image; under the condition that it is determined that the target gray-scale value is within a preset low gray-scale range, a target gray-scale coefficient corresponding to the target gray-scale value is determined based on a target corresponding relation, the target corresponding relation corresponds to the current gray-scale grade, and the low gray-scale range is determined based on the current gray-scale grade; based on the target gray scale coefficient, increasing the pulse width of an original PWM signal corresponding to the LED, and decreasing the frequency of the original PWM signal to obtain a target PWM signal; and controlling the brightness of the LED based on the target PWM signal. According to the application, the pulse width of the low-gray-scale PWM signal is increased, and the frequency of the low-gray-scale PWM signal is reduced, so that the phenomenon of non-uniform display is improved while the display intensity is not influenced, and the display effect is improved.

Description

Technical Field

[0001] This application relates to the technical field of LED backlight, and particularly relates to a backlight driving method, a driving chip, and a backlight module. Background Art

[0002] Pulse Width Modulation (PWM) is a technology widely used in Light Emitting Diode (LED) dimming. The basic principle of PWM technology is to adjust the brightness of the LED by adjusting the pulse width of the pulse signal.

[0003] At high gray levels, PWM technology can provide good brightness control and uniformity. However, since the response time of most LEDs is in the nanosecond level and there are differences in response time among different LEDs, at low gray levels, due to the very small effective pulse width of the PWM signal, this difference in response time is particularly obvious, resulting in differences in the actual brightness of the LEDs and uneven display. Summary of the Invention

[0004] This application provides a backlight driving method, a driving chip, and a backlight module to solve the problem of uneven backlight display in the prior art.

[0005] In a first aspect, this application provides a backlight driving method, including:

[0006] For the LEDs in the backlight module, determine the target gray level value of the pixel corresponding to the LED during the display of the current frame image;

[0007] When it is determined that the target gray level value is within a preset low gray level range, based on the target correspondence, determine the target gray level coefficient corresponding to the target gray level value, where the target correspondence corresponds to the current gray level grade, and the low gray level range is determined based on the current gray level grade;

[0008] Based on the target gray level coefficient, increase the pulse width of the original PWM signal corresponding to the LED and decrease the frequency of the original PWM signal to obtain a target PWM signal;

[0009] Based on the target PWM signal, control the brightness of the LED;

[0010] Based on the target PWM signal, control the LED.

[0011] In a possible implementation, the target correspondence is determined by the following method:

[0012] Determine the gray-scale values within the low gray-scale range among the gray-scale values corresponding to the current gray-scale level;

[0013] For each gray-scale value within the low gray-scale range, calculate the gray-scale coefficient corresponding to the gray-scale value based on the current gray-scale level and the gray-scale value;

[0014] Take the corresponding relationship between the gray-scale value and the gray-scale coefficient as the target corresponding relationship.

[0015] In a possible implementation, determine the low gray-scale range in the following manner:

[0016] Calculate 2 to the power of to obtain a first value, where s is the current gray-scale level;

[0017] Take the range greater than or equal to 1 and less than or equal to the first value as the low gray-scale range.

[0018] In a possible implementation, the calculation of the gray-scale coefficient corresponding to the gray-scale value based on the current gray-scale level and the gray-scale value includes:

[0019] Calculate a first calculated value corresponding to the gray-scale value based on the current gray-scale level and the gray-scale value;

[0020] Sort the gray-scale values within the second preset range in a first order, and sort the calculated first calculated values in a second order, where if the first order is from large to small, the second order is from small to large, and if the first order is from small to large, the second order is from large to small;

[0021] For each gray-scale value in the sorted gray-scale values, take the first calculated value at the same position as the gray-scale value in the sorted first calculated values as the gray-scale coefficient corresponding to the gray-scale value.

[0022] In a possible implementation, the calculation of the first calculated value corresponding to the gray-scale value based on the current gray-scale level and the gray-scale value includes:

[0023] Calculate the logarithm of the gray-scale value with base 2 to obtain a second calculated value;

[0024] Calculate the difference between the gray-scale level and the second calculated value;

[0025] Calculate 2 to the power of the difference to obtain a third calculated value;

[0026] Take the ratio of 1 to the third calculated value as the first calculated value corresponding to the gray-scale value.

[0027] In a possible implementation, adjusting the pulse width of the original PWM signal corresponding to the LED to be larger and reducing the frequency of the original PWM signal based on the target grayscale coefficient to obtain a target PWM signal includes:

[0028] Taking the quotient of the pulse width of the original PWM signal and the target grayscale coefficient as the target pulse width, and taking the product of the frequency of the original PWM signal and the target grayscale coefficient as the target frequency;

[0029] Generating the target PWM signal based on the target pulse width and the target frequency.

[0030] In a second aspect, the present application further provides a driving chip, including:

[0031] A determination module, configured to determine, for an LED in a backlight module, a target grayscale value of a pixel point corresponding to the LED during the display of the current frame image; and in the case where it is determined that the target grayscale value is within a preset low grayscale range, determining a target grayscale coefficient corresponding to the target grayscale value based on a target correspondence relationship, where the target correspondence relationship corresponds to the current grayscale level, and the low grayscale range is determined based on the current grayscale level;

[0032] An adjustment module, configured to adjust the pulse width of the original PWM signal corresponding to the LED to be larger and reduce the frequency of the original PWM signal based on the target grayscale coefficient to obtain a target PWM signal;

[0033] A control module, configured to control the brightness of the LED based on the target PWM signal.

[0034] In a possible implementation, the determination module determines the target correspondence relationship in the following manner:

[0035] Determining the grayscale values within the low grayscale range among the grayscale values corresponding to the current grayscale level;

[0036] For each grayscale value within the low grayscale range, calculating a grayscale coefficient corresponding to the grayscale value based on the current grayscale level and the grayscale value;

[0037] Taking the correspondence relationship between the grayscale value and the grayscale coefficient as the target correspondence relationship.

[0038] In a possible implementation, the determination module determines the low grayscale range in the following manner:

[0039] Calculating 2 to the power to obtain a first value, where s is the current grayscale level;

[0040] Take the range greater than or equal to 1 and less than or equal to the first value as the low gray-scale range.

[0041] In a possible implementation, the determining module is specifically configured to:

[0042] Calculate a first calculated value corresponding to the gray-scale value based on the current gray-scale level and the gray-scale value;

[0043] Sort the gray-scale values within the second preset range in a first order, and sort the calculated first calculated values in a second order, where if the first order is from large to small, the second order is from small to large, and if the first order is from small to large, the second order is from large to small;

[0044] For each gray-scale value in the sorted gray-scale values, take the first calculated value at the same position as the gray-scale value in the sorted first calculated values as the gray-scale coefficient corresponding to the gray-scale value.

[0045] In a possible implementation, the determining module is specifically configured to:

[0046] Calculate the logarithm of the gray-scale value with base 2 to obtain a second calculated value;

[0047] Calculate the difference between the gray-scale level and the second calculated value;

[0048] Calculate 2 to the power of the difference to obtain a third calculated value;

[0049] Take the ratio of 1 to the third calculated value as the first calculated value corresponding to the gray-scale value.

[0050] In a possible implementation, the adjusting module is specifically configured to:

[0051] Take the quotient of the pulse width of the original PWM signal and the target gray-scale coefficient as the target pulse width, and take the product of the frequency of the original PWM signal and the target gray-scale coefficient as the target frequency;

[0052] Generate the target PWM signal based on the target pulse width and the target frequency.

[0053] In a third aspect, the present application further provides a backlight module, including the driving chip according to any one of the second aspects, and an LED electrically connected to the driving chip.

[0054] The beneficial effects of the present invention are as follows:

[0055] A backlight driving method, a driving chip, and a backlight module provided by the present application determine, for an LED in the backlight module, a target gray level value of a pixel point corresponding to the LED during the display of the current frame image; in the case where the target gray level value is within a preset low gray level range, based on a target correspondence relationship, determine a target gray level coefficient corresponding to the target gray level value, where the target correspondence relationship corresponds to the current gray level grade, and the low gray level range is determined based on the current gray level grade; based on the target gray level coefficient, increase the pulse width of the original PWM signal corresponding to the LED, and decrease the frequency of the original PWM signal to obtain a target PWM signal; control the LED based on the target PWM signal. In the embodiment of the present application, if the target gray level value is within the low gray level range, then determine the target gray level coefficient corresponding to the target gray level value, then increase the pulse width of the original PWM signal based on the target gray level coefficient, decrease the frequency of the original PWM signal, and finally control the brightness of the LED based on the adjusted PWM signal. Since the pulse width of the PWM signal at low gray levels is increased and the frequency of the PWM signal at low gray levels is decreased, the phenomenon of uneven display is improved without affecting the display intensity, and the display effect is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings without creative efforts based on these drawings.

[0057] Figure 1 A schematic diagram of an application scenario of the backlight driving method provided by the embodiment of the present application;

[0058] Figure 2 A schematic flow chart of a backlight driving method provided by the embodiment of the present application;

[0059] Figure 3 A schematic flow chart of calculating a first calculated value provided by the embodiment of the present application;

[0060] Figure 4 A schematic diagram of an original PWM signal provided by the embodiment of the present application;

[0061] Figure 5 A schematic diagram of a target PWM signal provided by the embodiment of the present application;

[0062] Figure 6 A schematic structural diagram of a driving chip provided by the embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0063] To make the objectives, technical solutions, and advantages of this application clearer, the following will further describe this application in detail with reference to the accompanying drawings. Apparently, the described embodiments are only a part of the embodiments of this application, rather than all of them. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of this application.

[0064] It should be noted that the terms "first", "second", etc. in the description and claims of this application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of this application described here can be implemented in an order other than those illustrated or described here. The implementation manners described in the following exemplary embodiments do not represent all implementation manners consistent with this application. On the contrary, they are merely examples of devices and methods consistent with some aspects of this application as detailed in the appended claims.

[0065] With the continuous development of the display industry, the requirements for image quality are getting higher and higher. Gray-scale fineness and refresh rate are important parameters for measuring image quality. Usually, gray-scale levels are used to describe gray-scale fineness. For example, the gray-scale level is 16 bit (bits), that is, 16-bit gray scale. 16-bit gray scale can provide 2 16 ^16 = 65536 different gray-scale values. The 65536 gray-scale values include 0 to 65535. The gray-scale value refers to the value corresponding to a certain brightness. Therefore, the 65536 gray-scale values also represent 65536 brightness changes. The refresh rate refers to the number of times the LED switches on and off per second under the control of the PWM signal. The higher the refresh rate, the lighter the stroboscopic effect and the more natural the light.

[0066] In display technology, to adjust the brightness of the LED in the backlight module, the PWM technology is usually adopted, that is, a PWM signal is sent to the LED. When the effective pulse width of the PWM signal acts on the LED, the LED emits light due to the conduction current. When the ineffective pulse width of the PWM acts on the LED, the LED is turned off due to the current being cut off.

[0067] When using the PWM technology to control the LED brightness, the brightness of the LED is controlled by changing the pulse width of the PWM signal. The effective pulse width of the PWM signal is calculated through the gray-scale value, the number of gray scales, and the refresh rate. Among them, the number of gray scales is 2 n ^n, where n is the gray-scale level. Specifically, the effective pulse width of the PWM signal can be calculated by the following formula: effective pulse width = gray-scale value / number of gray scales / refresh rate.

[0068] For example, the gray-scale level is 16 bit, and the refresh rate is 3840 Hz. Since 16-bit gray scale can provide 2 16= 65,536 different grayscale values, that is, the number of grayscale levels is 65,536. Therefore, the effective pulse widths of the PWM signals include 65,536. The minimum effective pulse width of the PWM signal = 1 / 65,536 / 3840 = 3.97364×10 -9 seconds.

[0069] It should be noted that when the grayscale value is 0, the effective pulse width of the PWM signal is close to 0. Therefore, the effective pulse width of the PWM signal corresponding to the 0 grayscale value is not calculated using the above formula.

[0070] As Figure 1 shown, it is a schematic diagram of an application scenario of the backlight driving method provided by an embodiment of the present application. The backlight module 13 includes an LED 131 and a driving chip 132. The driving chip 132 is connected to a plurality of LEDs 131. Figure 1 In

[0071] this case, one driving chip 132 is connected to two LEDs 131. The driving chip 132 sends a PWM signal to the LEDs 131 connected to the driving chip 132 to control the brightness of the LEDs 131, thereby realizing the adjustment of the brightness of the backlight module 13.

[0071] When displaying a frame of image, the driving chip 132 calculates the pulse width of the PWM signal according to the refresh rate and the grayscale value of the pixel points corresponding to the LEDs connected to the driving chip 132. Here, the pulse width, that is, the effective pulse width. The smaller the grayscale value, the lower the gray level, and the smaller the calculated pulse width of the PWM signal. For example, the grayscale level is 16 bit and the refresh rate is 3840 Hz. When the grayscale value of the pixel point corresponding to the LED is 1, the effective pulse width of the PWM signal is 3.97364×10 -9 seconds. When the grayscale value of the pixel point corresponding to the LED is 2, the effective pulse width of the PWM signal is 7.9473×10 -9 seconds. When the grayscale value of the pixel point corresponding to the LED is 3, the effective pulse width of the PWM signal is 11.9209×10 -9 seconds.

[0072] When the effective pulse width of the PWM signal is at the nanosecond level, it is required that the driving chip realizes nanosecond-level PWM pulse width control. Nanosecond-level control poses a certain difficulty for the driving chip. In addition, since the response time of most LEDs is at the nanosecond level and there are differences in the response time among different LEDs, when the effective pulse width of the PWM signal is very small, the difference in the response time among the LEDs is particularly obvious, resulting in uneven display.

[0073] Figure 2

[0074] S201: Determine the target gray level value of the pixel corresponding to the LED in the backlight module during the display of the current frame image;

[0075] S202: When it is determined that the target gray level value is within the preset low gray level range, determine the target gray level coefficient corresponding to the target gray level value based on the target correspondence relationship, where the target correspondence relationship corresponds to the current gray level;

[0076] S203: Based on the target gray level coefficient, increase the pulse width of the original PWM signal corresponding to the LED and decrease the frequency of the original PWM signal to obtain the target PWM signal;

[0077] S204: Control the brightness of the LED based on the target PWM signal.

[0078] In the embodiment of the present application, for the LED in the backlight module, determine the target gray level value of the pixel corresponding to the LED during the display of the current frame image; when it is determined that the target gray level value is within the preset low gray level range, determine the target gray level coefficient corresponding to the target gray level value based on the target gray level value and the current gray level, where the target correspondence relationship corresponds to the current gray level, and the low gray level range is determined based on the current gray level; based on the target gray level coefficient, increase the pulse width of the original PWM signal corresponding to the LED and decrease the frequency of the original PWM signal to obtain the target PWM signal; control the LED based on the target PWM signal. In the embodiment of the present application, if the target gray level value is within the low gray level range, then determine the target gray level coefficient corresponding to the target gray level value, then increase the pulse width of the original PWM signal based on the target gray level coefficient and decrease the frequency of the original PWM signal, and finally control the brightness of the LED based on the adjusted PWM signal. Since the pulse width of the PWM signal at low gray levels is increased and the frequency of the PWM signal at low gray levels is decreased, the phenomenon of uneven display is improved without affecting the display intensity, and the display effect is improved.

[0079] The LED in the embodiment of the present application may be a Mini LED.

[0080] In a specific implementation, one pixel of the display interface corresponds to at least one LED in the backlight module. When displaying the current frame image, the driving chip first determines the target gray level value of the pixel corresponding to the LED connected to it. If the target gray level value is within the preset low gray level range, based on the target gray level value and the current gray level grade, the target gray level coefficient corresponding to the target gray level value is determined. Based on this target gray level coefficient, the pulse width of the original PWM signal corresponding to the LED is increased, and the frequency of the original PWM signal corresponding to the LED is decreased to obtain the target PWM signal, and the brightness of the LED is controlled based on the target PWM signal; if the target gray level value is within the preset high gray level range, the brightness of the LED is controlled based on the original PWM signal.

[0081] In the embodiment of the present application, when determining the target gray level coefficient corresponding to the target gray level value based on the target gray level value and the current gray level grade, the corresponding relationship corresponding to each gray level grade can be preset and stored. The corresponding relationship is the corresponding relationship between the gray level value and the gray level coefficient. After determining that the target gray level value is within the preset low gray level range, the target corresponding relationship corresponding to the current gray level grade is searched, and the target gray level coefficient corresponding to the target gray level grade is searched from the target corresponding relationship. The following details how to determine the corresponding relationship corresponding to the gray level grade.

[0082] In one embodiment, the target corresponding relationship, that is, the corresponding relationship corresponding to the current gray level grade, is determined in the following way. First, the gray level values located within the preset low gray level range are determined from the gray level values corresponding to the current gray level grade. Then, for each gray level value among the determined gray level values, based on the current gray level grade s and the gray level value h, the gray level coefficient f(h) corresponding to the gray level value is calculated. Finally, the corresponding relationship between the gray level value h and the gray level coefficient f(h) corresponding to the gray level value is used as the target corresponding relationship.

[0083] In a specific implementation, the low gray level range can be determined in the following way. Calculate 2 to the power to obtain the first value A (i.e., ), and the range greater than or equal to 1 and less than or equal to the first value A is used as the low gray level range, that is, the low gray level range is where s is the current gray level grade;

[0084] In the embodiment of the present application, in addition to including the low gray level range, it also includes a preset high gray level range. The high gray level range can be determined in the following way. Calculate 2 to the power of s, and use the difference between 2 to the power of s and 1 as the second value B (i.e., B = 2 s - 1), and the range greater than the first value A and less than or equal to the second value B is used as the high gray level range, that is, the high gray level range is

[0085] For example, the grayscale level s is 8 bits, and the first value The second value B = 2 s = 2 8 = 256. The low grayscale range is 1 ≤ h ≤ 16, and the high grayscale range is 16 < h < 256. That is to say, the grayscale values from 1 to 16 correspond to the low grayscale, and the grayscale values from 17 to 255 correspond to the high grayscale.

[0086] It should be noted that since the pulse width of the PWM signal is close to 0 when the grayscale value is 0, therefore, there is no need to adjust the pulse width of the PWM signal corresponding to the 0 grayscale value.

[0087] In the embodiments of the present application, when determining the corresponding relationship corresponding to the grayscale level, first, based on the grayscale level, determine the low grayscale range, then, from the grayscale values corresponding to the grayscale level, determine the grayscale values located within the low grayscale range, and then, based on the grayscale level s and the grayscale value h, calculate the grayscale coefficient f(h) corresponding to the grayscale value.

[0088] In a specific implementation, when determining the low grayscale range based on the grayscale level, the high grayscale range can also be determined based on the grayscale level. Since the PWM signals corresponding to the grayscale values within the high grayscale range are not adjusted, therefore, in a specific implementation, the high grayscale range can be determined in advance or not determined. The embodiments of the present application do not make any limitations in this regard.

[0089] In one embodiment, when calculating the grayscale coefficient corresponding to the grayscale value located within the low grayscale range, first, for each grayscale value located within the low grayscale range, based on the current grayscale level s and the grayscale value h, calculate the first calculated value corresponding to the grayscale value h; then sort the grayscale values within the low grayscale range in the first order, and sort the calculated first calculated values in the second order, where the first order and the second order are different. If the first order is from large to small, then the second order is from small to large. If the first order is from small to large, then the second order is from large to small; finally, for each grayscale value in the sorted grayscale values, use the first calculated value at the same position as the grayscale value in the sorted first calculated values as the grayscale coefficient corresponding to the grayscale value.

[0090] Specifically, as Figure 3 shown, it is a schematic flow chart of calculating the first calculated value provided by the embodiments of the present application:

[0091] S301: Calculate the logarithm of the grayscale value h with base 2 to obtain the second calculated value;

[0092] S302: Calculate the difference between the current grayscale level s and the second calculated value;

[0093] S303: Calculate the difference power of 2 to obtain the third calculated value;

[0094] S304: Use the ratio of 1 to the third calculated value as the first calculated value corresponding to the grayscale value h.

[0095] In the embodiment of the present application, after determining that the grayscale value h is within the low grayscale range (i.e., ), first calculate the second calculated value (i.e., the second calculated value = log2h), then calculate the difference between the current grayscale level s and the second calculated value (i.e., s - log2h), then calculate the third calculated value (i.e., ), and finally calculate the first calculated value (i.e., ).

[0096] After calculating multiple first calculated values, sort the grayscale values within the low grayscale range in the first order, sort the calculated first calculated values in the second order, and for each grayscale value in the sorted grayscale values, use the first calculated value at the same position as the grayscale value in the sorted first calculated values as the grayscale coefficient corresponding to the grayscale value.

[0097] For example, the grayscale values within the low grayscale range include h1, h2, h3, h4, and the calculated first calculated values include m, p, k, e. As shown in Table 1, the first calculated value e is calculated based on the grayscale value h1, the first calculated value k is calculated based on the grayscale value h2, the first calculated value p is calculated based on the grayscale value h3, and the first calculated value m is calculated based on the grayscale value h4.

[0098] The first order is from largest to smallest, and the second order is from smallest to largest. Sort the grayscale values in the first order. As shown in Table 1, the sorted grayscale values are h4, h3, h2, h1, and the sorted first calculated values are e, k, p, m.

[0099] Gray scale value First calculated value Sorted first calculated value h4 m e h3 p k h2 k p h1 e m

[0100] Table 1

[0101] It can be seen from Table 1 that the grayscale coefficient f(h) corresponding to the grayscale value h4 is e; the grayscale coefficient f(h) corresponding to the grayscale value h3 is k; the grayscale coefficient f(h) corresponding to the grayscale value h2 is p; the grayscale coefficient f(h) corresponding to the grayscale value h1 is m.

[0102] For another example, the gray scale values within the low gray scale range include h1, h2, h3, h4, and the calculated first calculated values include m, p, k, e. As shown in Table 2, the first calculated value e is calculated based on the gray scale value h1, the first calculated value k is calculated based on the gray scale value h2, the first calculated value p is calculated based on the gray scale value h3, and the first calculated value m is calculated based on the gray scale value h4.

[0103] The first order is the order from small to large, and the second order is the order from large to small. Sort the gray scale values in the first order. As shown in Table 2, the sorted gray scale values are h1, h2, h3, h4, and the sorted first calculated values are m, p, k, e.

[0104] Gray scale value First calculated value Sorted first calculated value h1 e m h2 k p h3 p k h4 m e

[0105] Table 2

[0106] As can be seen from Table 2, the gray scale coefficient f(h) corresponding to the gray scale value h1 is m; the gray scale coefficient f(h) corresponding to the gray scale value h2 is p; the gray scale coefficient f(h) corresponding to the gray scale value h3 is k; the gray scale coefficient f(h) corresponding to the gray scale value h4 is e.

[0107] For ease of understanding, the present application will be described below with specific embodiments.

[0108] For example, the gray scale level s is 12bit, the refresh rate M is 3840Hz, the first order is from small to large, and the second order is from large to small. Determine the corresponding relationship corresponding to the gray scale level s and calculate the first value After calculating the first value A, determine that the low gray scale range is 1 ≤ h ≤ 64.

[0109] For each gray scale value within the low gray scale range of 1 ≤ h ≤ 64, calculate the corresponding After obtaining the first calculated value corresponding to each gray scale value, sort the gray scale values within the low gray scale range in the first order, sort the calculated first calculated values in the second order, and for each gray scale value in the sorted gray scale values, use the first calculated value at the same position as the gray scale value in the sorted first calculated values as the gray scale coefficient corresponding to the gray scale value, as shown in Table 3.

[0110]

[0111] Table 3

[0112] It can be obtained from Table 3 that the corresponding relationship corresponding to the gray scale level 12bit can refer to Table 4:

[0113] Gray scale value h Gray scale coefficient f(h) 1 0.01563 2 0.01538 3 0.01514 4 0.01489 ...... ...... 61 0.000976 62 0.000732 63 0.000488 64 0.000244

[0114] Table 4

[0115] In a specific implementation, it can be considered that there is also a gray scale coefficient for the gray scale value within the high gray scale range. The gray scale coefficient corresponding to the gray scale value within the high gray scale range is determined to be 1, and the original PWM signal is adjusted using the gray scale coefficient 1, that is, the pulse width of the original PWM signal and the frequency of the original PWM signal are not adjusted.

[0116] In the embodiments of the present application, the gray scale coefficient satisfies the following functional relationship:

[0117]

[0118] where f(h) is the gray scale coefficient, h is the gray scale value, and s is the gray scale level.

[0119] The above function can also be expressed as:

[0120]

[0121] Since the number of gray scale values h is 2 s , when dividing the gray scale values into high gray scale and low gray scale, the inverse operation of h = 2 s is used, that is, log2h. log2h is divided into two parts, one part is greater than or equal to 0 and less than or equal to and the other part is greater than and less than s. After dividing log2h, the low gray scale range can be obtained as and the high gray scale range is

[0122] The above is the method provided by the embodiments of the present application to determine the corresponding relationship corresponding to the gray scale level. Next, after finding the target gray scale coefficient corresponding to the target gray scale value in the target corresponding relationship in the embodiments of the present application, how to increase the pulse width of the original PWM signal corresponding to the LED and decrease the frequency of the original PWM signal will be described.

[0123] In a specific implementation, the quotient of the pulse width of the original PWM signal and the target gray scale coefficient is used as the target pulse width, and the product of the frequency of the original PWM signal and the target gray scale coefficient is used as the target frequency; based on the target pulse width and the target frequency, a target PWM signal is generated.

[0124] In a specific implementation, the pulse width L1 of the original PWM signal = h / H / M, that is where h is the gray scale value, H is the number of gray scales, and M is the refresh rate. The frequency f1 of the original PWM signal is the same as the refresh rate M.

[0125] Calculate the quotient of the pulse width L1 of the original PWM signal and the gray scale coefficient f(h), and use the quotient as the target pulse width L2, that is Since the calculated f(h) values are all decimals, L2 is greater than L1;

[0126] Calculate the product of the frequency f1 of the original PWM signal and the grayscale coefficient f(h), and use the product as the target frequency f2, that is, f2 = f1 × f(h). Similarly, since the calculated f(h) is a decimal, f2 is less than f1.

[0127] Generate a target PWM signal based on the target pulse width L2 and the target frequency f2, and control the brightness of the LED based on the target PWM signal.

[0128] In the embodiments of the present application, increasing the pulse width of the original PWM signal can improve the problem of uneven display, and reducing the frequency of the original PWM signal can ensure that the luminous intensity remains unchanged, so that normal display can be achieved.

[0129] The following uses specific embodiments to illustrate the present application.

[0130] For example, the response time of LED1 on the backlight module is 10 nanoseconds, and the response time of LED2 is 5 nanoseconds. The response times of LED1 and LED2 are different. It should be noted that the response time of the LED is the time from off to on.

[0131] Under the settings of a frame rate of 60Hz, a grayscale level of 12bit, and a refresh rate of 3840Hz, there are 64 PWM cycles in one frame. That is to say, within one frame time, the LED has to go from off to on 64 times. When the grayscale value is 1, the theoretical pulse width of the PWM signal is 63.578 nanoseconds. Therefore, when the grayscale value is 1, within one frame time, the total on-time of the LED is 63.578 × 64 = 4068.992 nanoseconds. The time consumed by LED1 for 64 responses is 10 × 64 = 640 nanoseconds, and the actual total on-time of LED1 is 4068.992 - 640 = 3428.992 nanoseconds, which is 84.27% of the theoretical brightness; the time consumed by LED2 for 64 responses is 5 × 64 = 320 nanoseconds, and the actual total on-time of LED2 is 4068.1992 - 320 = 3748.992 nanoseconds, which is 92.14% of the theoretical brightness. The brightness difference between LED1 and LED2 is 7.87%.

[0132] Referring to Table 4, the grayscale coefficient f(h) corresponding to the grayscale value 1 is 0.01563. The theoretical pulse width of the original PWM signal corresponding to the grayscale value 1 nanoseconds, the frequency f1 of the original PWM signal corresponding to the grayscale value 1 is 3840Hz; after adjusting the original PWM signal with the grayscale coefficient 0.01563 corresponding to the grayscale value 1, the theoretical pulse width of the target PWM signal In nanoseconds, the frequency f2 of the target PWM signal is 3840 × 0.01563 = 60.0192 Hz.

[0133] Since the frequency of the target PWM signal becomes 60.0192 Hz, therefore, at low gray levels, the refresh rate becomes 60.0192 Hz. Under the control of the target PWM signal, that is, with a frame rate of 60 Hz, a gray level of 12 bits, and a refresh rate of 60.0192 Hz, there are 1.00032 PWM cycles in one frame. That is to say, within one frame time, the LED needs to turn on and off 1.00032 times. When the gray level value is 1, the theoretical pulse width of the PWM signal is 4068.7 nanoseconds. Therefore, when the gray level value is 1, within one frame time, the total on-time of the LED is 4068.7 × 1.00032 = 4070 nanoseconds. The time consumed for LED1 to respond 1.00032 times is 10 × 1.00032 = 10.0032 nanoseconds, which is 10.0032 / 4068.7 × 100% = 0.25% of the theoretical brightness; the time consumed for LED2 to respond 1.00032 times is 5 × 1.00032 = 5.0016 nanoseconds, which is 5.0016 / 4068.7 × 100% = 0.123% of the theoretical brightness. The brightness difference between LED1 and LED2 is 0.127%.

[0134] It can be seen from this that under the control of the target PWM signal, the loss time of both LED1 and LED2 decreases, that is, the effective light-emitting time of LED1 and LED2 increases; at the same time, the brightness difference between LED1 and LED2 becomes smaller, thereby improving the phenomenon of uneven display.

[0135] As Figure 4 shown, it is a schematic diagram of an original PWM signal provided by an embodiment of the present application. As Figure 5 shown, it is a schematic diagram of a target PWM signal provided by an embodiment of the present application. Figure 4 and Figure 5 The PWM cycle in is the time interval between the starting point of one pulse and the starting point of the next pulse, including the sum of the high-level time and the low-level time of one pulse.

[0136] Figure 4 For the original PWM signal in, with a frame rate of 60 Hz, a gray level of 12 bits, and a refresh rate of 3840 Hz, the time of one frame is 16.67 milliseconds (i.e., one frame time = 1 / frame rate = 1 / 60). There are 3840 PWM cycles in 1 second. When the gray level value is the maximum value of 4095, the effective pulse width of the PWM signal is close to a straight line. At low gray levels, the pulse width of the original PWM signal is smaller. Figure 5The target PWM signal in it adjusts the pulse width and frequency of the original PWM signal at low gray levels, increases the pulse width of the original PWM signal, and decreases the frequency of the original PWM signal, thereby reducing the uneven display phenomenon at low gray levels, improving the display effect, and in addition, reducing the driving difficulty of the driving chip.

[0137] Based on the same concept, the embodiment of the present application also provides a driving chip, which is applied to a backlight module. The principle of the driving chip to solve the problem is similar to the above-mentioned backlight driving method. Therefore, the implementation of the driving chip can refer to the implementation of the backlight driving method, and the repeated parts will not be described again.

[0138] As Figure 6 shown, it is a schematic structural diagram of a driving chip provided by an embodiment of the present application. The chip includes:

[0139] A determination module 61, configured to determine, for an LED in a backlight module, a target gray level value of a pixel point corresponding to the LED during the display of the current frame image; in the case where it is determined that the target gray level value is within a preset low gray level range, based on a target correspondence relationship, determine a target gray level coefficient corresponding to the target gray level value, where the target correspondence relationship corresponds to the current gray level level, and the low gray level range is determined based on the current gray level level;

[0140] An adjustment module 62, configured to increase the pulse width of the original PWM signal corresponding to the LED and decrease the frequency of the original PWM signal based on the target gray level coefficient to obtain a target PWM signal;

[0141] A control module 63, configured to control the brightness of the LED based on the target PWM signal.

[0142] In a possible implementation manner, the determination module 61 determines the target correspondence relationship in the following manner:

[0143] Determine the gray level values within the low gray level range among the gray level values corresponding to the current gray level level;

[0144] For each gray level value within the low gray level range, calculate a gray level coefficient corresponding to the gray level value based on the current gray level level and the gray level value;

[0145] Take the correspondence relationship between the gray level value and the gray level coefficient as the target correspondence relationship.

[0146] In a possible implementation manner, the determination module 61 determines the low gray level range in the following manner:

[0147] Calculate 2 to the Raise it to the power of s to obtain a first value, where s is the current grayscale level;

[0148] Take the range greater than or equal to 1 and less than or equal to the first value as the low grayscale range.

[0149] In a possible implementation manner, the determining module 61 is specifically configured to:

[0150] Calculate a first calculated value corresponding to the grayscale value based on the current grayscale level and the grayscale value;

[0151] Sort the grayscale values within the second preset range in a first order, and sort the calculated first calculated values in a second order. Wherein, if the first order is from large to small, the second order is from small to large; if the first order is from small to large, the second order is from large to small;

[0152] For each grayscale value in the sorted grayscale values, take the first calculated value at the same position as the grayscale value in the sorted first calculated values as the grayscale coefficient corresponding to the grayscale value.

[0153] In a possible implementation manner, the determining module 61 is specifically configured to:

[0154] Calculate the logarithm of the grayscale value with base 2 to obtain a second calculated value;

[0155] Calculate the difference between the grayscale level and the second calculated value;

[0156] Calculate 2 to the power of the difference to obtain a third calculated value;

[0157] Take the ratio of 1 to the third calculated value as the first calculated value corresponding to the grayscale value.

[0158] In a possible implementation manner, the adjusting module 62 is specifically configured to:

[0159] Take the quotient of the pulse width of the original PWM signal and the target grayscale coefficient as the target pulse width, and take the product of the frequency of the original PWM signal and the target grayscale coefficient as the target frequency;

[0160] Generate the target PWM signal based on the target pulse width and the target frequency.

[0161] Based on the same concept, an embodiment of the present application further provides a backlight module. The principle of the backlight module to solve the problem is similar to that of the above-mentioned driving chip. Therefore, the implementation of the backlight module can refer to the implementation of the driving chip, and the repeated parts will not be described again.

[0162] A backlight module provided by an embodiment of the present application includes a driving chip as described in any one of the above embodiments, and an LED electrically connected to the driving chip.

[0163] The present application provides a backlight driving method, a driving chip, and a backlight module. The method includes determining, for an LED in the backlight module, a target gray level value of a pixel point corresponding to the LED during the display of the current frame image; in the case where the target gray level value is within a preset low gray level range, determining a target gray level coefficient corresponding to the target gray level value based on a target correspondence relationship; based on the target gray level coefficient, increasing the pulse width of an original PWM signal corresponding to the LED and decreasing the frequency of the original PWM signal to obtain a target PWM signal; and controlling the LED based on the target PWM signal. In the embodiment of the present application, if the target gray level value is within the low gray level range, a target gray level coefficient corresponding to the target gray level value is determined, then the pulse width of the original PWM signal is increased based on the target gray level coefficient, the frequency of the original PWM signal is decreased, and finally, based on the adjusted PWM signal, the brightness of the LED is controlled. Since the pulse width of the PWM signal at low gray levels is increased and the frequency of the PWM signal at low gray levels is decreased, the phenomenon of uneven display is improved without affecting the display intensity, and the display effect is improved.

[0164] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memories, CD-ROMs, optical memories, etc.) containing computer-usable program codes.

[0165] The present application is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for implementing the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0166] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce a manufacture including instruction means that implement the function specified in the flowchart(s) Figure 1 one or more flowcharts and / or block diagrams Figure 1 specified in one or more blocks or a plurality of blocks.

[0167] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, whereby the instructions executed on the computer or other programmable apparatus provide steps for implementing the function specified in the flowchart(s) Figure 1 one or more flowcharts and / or block diagrams Figure 1 specified in one or more blocks or a plurality of blocks.

[0168] It is apparent that those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application is also intended to include these modifications and variations.

Claims

1. A backlight driving method, characterized in that: include: For an LED in a backlight module, determining a target grayscale value of a pixel corresponding to the LED in a process of displaying a current frame image; In the case where it is determined that the target grayscale value is within a preset low grayscale range, determining a target grayscale coefficient corresponding to the target grayscale value based on a target corresponding relationship, wherein the target corresponding relationship corresponds to a current grayscale level, and the low grayscale range is determined based on the current grayscale level; Based on the target grayscale coefficient, the pulse width of the original PWM signal corresponding to the LED is increased, and the frequency of the original PWM signal is decreased to obtain a target PWM signal; Based on the target PWM signal, the brightness of the LED is controlled.

2. The method according to claim 1, characterized in that The target correspondence is determined by: Determine a grayscale value that is within the low grayscale range among grayscale values ​​corresponding to the current grayscale level; For each grayscale value within the low grayscale range, based on the current grayscale level and the grayscale value, calculating a grayscale coefficient corresponding to the grayscale value; The correspondence between the grayscale value and the grayscale coefficient is used as the target correspondence.

3. The method according to claim 2, characterized in that The low grayscale range is determined by: Calculation 2 to the power of s, to obtain a first value, wherein s is the current grayscale level; A range greater than or equal to 1 and less than or equal to the first value is used as the low grayscale range.

4. The method according to claim 2, characterized in that: The calculating, based on the current grayscale level and the grayscale value, a grayscale coefficient corresponding to the grayscale value comprises: Based on the current grayscale level and the grayscale value, calculating a first calculated value corresponding to the grayscale value; Sorting the grayscale values ​​within the second preset range according to a first order, and sorting the calculated first calculated values ​​according to a second order, wherein if the first order is an order from large to small, then the second order is an order from small to large, and if the first order is an order from small to large, then the second order is an order from large to small; For each grayscale value in the sorted grayscale values, a first calculated value in the sorted first calculated values ​​that has the same position as the grayscale value is used as a grayscale coefficient corresponding to the grayscale value.

5. The method according to claim 4, characterized in that The calculating, based on the current grayscale level and the grayscale value, a first calculated value corresponding to the grayscale value comprises: Calculate the logarithm of the grayscale value with base 2 to obtain a second calculated value; Calculating a difference between the grayscale level and the second calculated value; Calculate the difference value of 2 to a power to obtain a third calculated value; The ratio of 1 to the third calculated value is used as a first calculated value corresponding to the grayscale value.

6. The method according to any one of claims 1 to 5, characterized in that: The step of increasing the pulse width of the original PWM signal corresponding to the LED and decreasing the frequency of the original PWM signal based on the target grayscale coefficient to obtain the target PWM signal includes: Taking the quotient of the pulse width of the original PWM signal and the target grayscale coefficient as the target pulse width, and taking the product of the frequency of the original PWM signal and the target grayscale coefficient as the target frequency; The target PWM signal is generated based on the target pulse width and the target frequency.

7. A driver chip, characterized in that: include: A determination module, for determining, for an LED in a backlight module, a target grayscale value of a pixel point corresponding to the LED in a process of displaying a current frame image; In the case where it is determined that the target grayscale value is within a preset low grayscale range, determining a target grayscale coefficient corresponding to the target grayscale value based on a target corresponding relationship, wherein the target corresponding relationship corresponds to a current grayscale level, and the low grayscale range is determined based on the current grayscale level; An adjustment module, configured to increase the pulse width of the original PWM signal corresponding to the LED and decrease the frequency of the original PWM signal based on the target grayscale coefficient to obtain a target PWM signal; A control module is used to control the brightness of the LED based on the target PWM signal.

8. The chip according to claim 7, characterized in that: The determination module determines the target correspondence relationship in the following manner: Determine a grayscale value that is within the low grayscale range among grayscale values ​​corresponding to the current grayscale level; For each grayscale value within the low grayscale range, based on the current grayscale level and the grayscale value, calculating a grayscale coefficient corresponding to the grayscale value; The correspondence between the grayscale value and the grayscale coefficient is used as the target correspondence.

9. The chip according to claim 8, characterized in that: The determination module determines the low grayscale range in the following manner: Calculation 2 to the power of s, to obtain a first value, wherein s is the current grayscale level; A range greater than or equal to 1 and less than or equal to the first value is used as the low grayscale range.

10. The chip according to claim 8, characterized in that: The determination module is specifically used for: Based on the current grayscale level and the grayscale value, calculating a first calculated value corresponding to the grayscale value; Sorting the grayscale values ​​within the second preset range according to a first order, and sorting the calculated first calculated values ​​according to a second order, wherein if the first order is an order from large to small, then the second order is an order from small to large, and if the first order is an order from small to large, then the second order is an order from large to small; For each grayscale value in the sorted grayscale values, a first calculated value in the sorted first calculated values ​​that has the same position as the grayscale value is used as a grayscale coefficient corresponding to the grayscale value.

11. The chip according to claim 10, characterized in that: The determination module is specifically used for: Calculate the logarithm of the grayscale value with base 2 to obtain a second calculated value; Calculating a difference between the grayscale level and the second calculated value; Calculate the difference value of 2 to a power to obtain a third calculated value; The ratio of 1 to the third calculated value is used as a first calculated value corresponding to the grayscale value.

12. The chip according to any one of claims 7 to 11, characterized in that: The adjustment module is specifically used for: Taking the quotient of the pulse width of the original PWM signal and the target grayscale coefficient as the target pulse width, and taking the product of the frequency of the original PWM signal and the target grayscale coefficient as the target frequency; The target PWM signal is generated based on the target pulse width and the target frequency.

13. A backlight module, characterized in that: The invention comprises a driving chip as claimed in any one of claims 7 to 12, and an LED electrically connected to the driving chip.

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