CN111341272A - Backlight control method, system, terminal and computer readable storage medium - Google Patents
Backlight control method, system, terminal and computer readable storage medium Download PDFInfo
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- CN111341272A CN111341272A CN201811641073.3A CN201811641073A CN111341272A CN 111341272 A CN111341272 A CN 111341272A CN 201811641073 A CN201811641073 A CN 201811641073A CN 111341272 A CN111341272 A CN 111341272A
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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
- G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
- G09G3/3406—Control of illumination source
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
- G09G3/3406—Control of illumination source
- G09G3/3413—Details of control of colour illumination sources
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Abstract
The invention belongs to the technical field of liquid crystal screens, and provides a backlight control method, a system, a terminal and a computer readable storage medium, which are used for a liquid crystal screen, wherein the liquid crystal screen comprises a backlight unit and a liquid crystal unit, and the relationship between the preset display brightness and a dimming threshold value is judged by acquiring the preset display brightness; setting the brightness of the backlight unit according to the strength relation between the preset display brightness and the dimming threshold; and further setting the backlight transmittance of the liquid crystal unit according to the preset display brightness and the set light-emitting brightness. Therefore, different luminance and backlight transmittance are correspondingly set according to the strength relation between the preset display brightness and the dimming threshold, and the problem of difficulty in gray control of a large-current area of the discrete MOS tube is solved; the control mode has high flexibility, improves the contrast of a screen, and solves the problem that the gray level adjustment precision is low in the existing control technology for the dynamic backlight liquid crystal screen.
Description
Technical Field
The invention belongs to the technical field of liquid crystal screens, and particularly relates to a backlight control method, a backlight control system, a backlight control terminal and a computer readable storage medium.
Background
Currently, LED backlight technology is usually driven in a static or passive manner. Compared with the conventional technology, the active driving method for driving the Light Emitting element has the advantages of high contrast, energy saving, and the like, and is commonly used for liquid crystal panels or OLEDs (Organic Light-Emitting diodes).
For a conventional LED backlight driving circuit, an active backlight driving is usually performed based on MOSFET discrete components, that is, MOSFET tubes are connected in series with LEDs and provide driving current for the LEDs. However, due to the limitation of the IV characteristic of the MOSFET discrete device, the accuracy of controlling the current Ids with the voltage Vg is relatively low, and it is considered that the relationship between the driving voltage and the light emitting luminance of the LED brings a large error, which makes it difficult to achieve the accurate control of the gray scale in the above manner.
Therefore, the existing control technology for the dynamic backlight liquid crystal screen has the problem of low gray scale adjustment precision.
Disclosure of Invention
The invention aims to provide a backlight control method, a backlight control system, a terminal and a computer readable storage medium, and aims to solve the problem that the existing control technology for a dynamic backlight liquid crystal screen is low in gray scale adjustment precision.
The invention provides a backlight control method, which is used for a liquid crystal screen, wherein the liquid crystal screen comprises a backlight unit and a liquid crystal unit, and the backlight control method comprises the following steps:
acquiring preset display brightness, and judging the strength relation between the preset display brightness and a dimming threshold;
setting the brightness of the backlight unit according to the strength relation between the preset display brightness and the dimming threshold;
and setting the backlight transmissivity of the liquid crystal unit according to the preset display brightness and the set light-emitting brightness.
A second aspect of the present invention provides a backlight control system for a liquid crystal panel, the liquid crystal panel including a backlight unit and a liquid crystal unit, the backlight control system comprising:
the display brightness judging module is used for acquiring preset display brightness and judging the strength relation between the preset display brightness and a dimming threshold;
the light-emitting brightness setting module is used for setting the light-emitting brightness of the backlight unit according to the strength relation between the preset display brightness and the dimming threshold;
and the backlight transmittance setting module is used for setting the backlight transmittance of the liquid crystal unit according to the preset display brightness and the set light-emitting brightness.
A third aspect of the present invention provides a terminal, comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the backlight control method as described above when executing the computer program.
A fourth aspect of the present invention provides a computer-readable storage medium storing a computer program, wherein the computer program, when executed by a processor, implements the steps of the backlight control method as described above.
The invention provides a backlight control method, a backlight control system, a terminal and a computer readable storage medium, which are used for a liquid crystal screen, wherein the liquid crystal screen comprises a backlight unit and a liquid crystal unit, and the relationship between the preset display brightness and a dimming threshold value is judged by acquiring the preset display brightness; setting the brightness of the backlight unit according to the strength relation between the preset display brightness and the dimming threshold; and further setting the backlight transmittance of the liquid crystal unit according to the preset display brightness and the set light-emitting brightness. Therefore, different luminance and backlight transmittance are correspondingly set according to the strength relation between the preset display brightness and the dimming threshold, and the problem of difficulty in gray control of a large-current area of the discrete MOS tube is solved; the control mode has high flexibility, improves the contrast of a screen, and solves the problem that the gray level adjustment precision is low in the existing control technology for the dynamic backlight liquid crystal screen.
Drawings
Fig. 1 is a flowchart illustrating steps of a backlight control method according to an embodiment of the invention.
Fig. 2 is an exemplary circuit diagram of a basic circuit of 2T1C of the active driving unit provided by the present invention.
FIG. 3 is I for the discrete component MOS2 transistor of FIG. 2ds-VgsIs a graph of the relationship of (A).
FIG. 4 is a graph of a model of the graph of the luminance versus the driving voltage established for FIG. 2.
Fig. 5 is a schematic flowchart illustrating a detailed implementation of a backlight control method according to an embodiment of the present invention.
Fig. 6 is a schematic block diagram of a backlight control system according to another embodiment of the present invention.
Fig. 7 is a schematic structural diagram of a specific module of a backlight control system according to another embodiment of the present invention.
Fig. 8 is a schematic cross-sectional view illustrating a liquid crystal panel and an LED display unit in a backlight control system according to another embodiment of the invention.
Fig. 9 is a schematic structural diagram of a backlight control system according to another embodiment of the present invention.
Fig. 10 is a schematic structural diagram of a terminal according to yet another embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The backlight control method, the backlight control system, the terminal and the computer readable storage medium are used for a liquid crystal screen, wherein the liquid crystal screen comprises a backlight unit and a liquid crystal unit, and the relationship between the preset display brightness and the dimming threshold value is judged by acquiring the preset display brightness; setting the brightness of the backlight unit according to the strength relation between the preset display brightness and the dimming threshold; and further setting the backlight transmittance of the liquid crystal unit according to the preset display brightness and the set light-emitting brightness. Therefore, different luminance and backlight transmittance are correspondingly set according to the strength relation between the preset display brightness and the dimming threshold, and the problem of difficulty in gray control of a large-current area of the discrete MOS tube is solved; the flexibility of this control mode is stronger, has promoted the contrast of screen, and user's experience feels stronger.
Fig. 1 shows a flow of steps of a backlight control method according to the present invention, and for convenience of description, only the parts related to the present embodiment are shown, which are detailed as follows:
the backlight control method is used for a liquid crystal screen, the liquid crystal screen comprises a backlight unit and a liquid crystal unit, and the backlight control method comprises the following steps:
s101, acquiring preset display brightness, and judging the strength relation between the preset display brightness and a dimming threshold;
in an embodiment, the dimming threshold is set to be a product of a maximum backlight transmittance and a preset light emitting luminance, wherein the maximum backlight transmittance is a maximum value of the backlight transmittances in the plurality of backlight lattices provided for the liquid crystal cell. In the liquid crystal unit, a plurality of pixel points are arranged, and each pixel point is correspondingly provided with backlight transmittance, so that a plurality of backlight transmittances can appear. A maximum value is selected among the plurality of backlight transmittances, i.e., defined as a maximum backlight transmittance.
S102, setting the brightness of the backlight unit according to the strength relation between preset display brightness and a dimming threshold;
because the brightness of the backlight unit is set according to the strength relation between the preset display brightness and the dimming threshold, the brightness of the backlight unit can be flexibly adjusted, namely dynamically changed. Specifically, when the preset display brightness is stronger than the dimming threshold, the light-emitting brightness of the backlight unit is a fixed value, and the screen adopts the same display mode as the traditional static backlight; when the preset display brightness is weaker than the dimming threshold, the light emitting brightness of the backlight unit changes in real time with the change of the preset display brightness, and then the screen should adopt a dynamic backlight algorithm. Referring to fig. 3, the case where the preset display luminance is stronger than the dimming threshold corresponds to a large current region of the discrete MOS transistor. Meanwhile, the situation that the preset display brightness is weaker than the dimming threshold corresponds to a low-current region of the discrete MOS tube, and due to the adoption of a dynamic backlight algorithm, the brightness of the backlight unit is flexibly adjusted, the gray scale adjustment precision is greatly improved, and the problem that the discrete MOS tube is difficult to control the gray scale in the high-current region is solved.
And S103, setting the backlight transmittance of the liquid crystal unit according to the preset display brightness and the set light emitting brightness.
Specifically, after the luminance of the backlight unit is set, the backlight transmittance of the liquid crystal unit is obtained, and the two are in an inverse proportional relationship. In this embodiment, the quotient obtained by dividing the preset display brightness value by the set brightness value is used to obtain the backlight transmittance of the liquid crystal cell and set the backlight transmittance, which is specifically obtained by the following formula:
T＝L/B
wherein, T is the backlight transmittance of the liquid crystal cell, L is the preset display brightness, and B is the set brightness.
The brightness of the backlight unit can be flexibly adjusted, so that the backlight transmissivity of the liquid crystal unit is correspondingly changed, the effect of stronger flexibility of the control method is achieved, the contrast of a screen is improved, and the user experience is stronger.
In an embodiment, the setting and the operation principle of the large current region and the small current region are described with reference to fig. 2 to 4:
in fig. 2, a 2T1C basic circuit is taken as an example, and a MOSFET tube (shown as MOS2 in fig. 2) capable of bearing a large current is connected in series with an LED to provide a driving current for the LED. With MOS1 turned on, drive voltage VdataThe LEDs are powered sequentially through MOS1 and MOS 2.
When dynamic dimming is performed through the circuit structure, as can be seen from the Ids-Vgs relationship of the discrete MOS2 transistor in fig. 3, the IV curve has a large dynamic resistance when the current is small, that is, the variation range of Vgs is large in the process of Ids variation; conversely, when the current is large, the dynamic resistance is small. Simultaneous combination of drawings4 the luminance (shown by LED luminance B in FIG. 4) and the driving voltage (shown by V in FIG. 4) of the backlight unitdataIs shown, and VdataEquivalent to V in FIG. 3gs) Establishing a curve model, wherein the driving voltage is used for driving the liquid crystal display, and the curve model is divided into a large current area and a small current area according to the slope of the curve, namely, when the slope of the curve is greater than a preset angle value, the corresponding area is divided into the large current area; and when the slope of the curve is smaller than the preset angle value, dividing the corresponding area into a small current area. The light emission luminance corresponding to the boundary point between the large current region and the small current region is set to a preset light emission luminance (fig. 4 adopts B)TRepresentation).
Therefore, the curve of the large-current area is extremely steep, the driving voltage is used for controlling the light-emitting brightness, the error is large, and the light-emitting brightness deviation caused by the error brought by the driving voltage is more sensitive in the large-current area than in the small-current area, namely, the light-emitting brightness can be greatly changed when the driving voltage changes slightly in the large-current area. As can be seen from the above analysis, the error is large when the brightness B of the LED is controlled in the large current region, and the accuracy is relatively high when the control is performed in the small current region. Therefore, the driving voltage corresponding to the boundary between the large current region and the small current region is defined as VTI.e. when the Vgs voltage is less than VTThe dynamic resistance of the MOS2 is larger, the current can be accurately controlled, and the corresponding luminous brightness is BT. Conversely, when the Vgs voltage is greater than VTAt times, the dynamic resistance of MOS2 is small and its current cannot be precisely controlled.
Therefore, the large current region and the small current region are set, and different display control methods are respectively adopted for the large current region and the small current region:
in a large current region, a display mode of a traditional static backlight is adopted as long as the driving voltage is more than VTThen, the light emission luminance is set to a fixed value, for example, the light emission luminance is fixed to correspond to B in fig. 4max；
In the low current region, with dynamic backlightingDisplay mode, i.e. with a drive voltage less than or equal to VTThen, the gray-scale value of the luminance is correspondingly obtained according to the change of the driving voltage, for example: when the driving voltage is V1When it is, the luminance is B1(ii) a When the driving voltage is V2When it is, the luminance is B2(ii) a When the driving voltage is VTWhen it is, the luminance is BT… … it can be seen that in the low current region, the light emission brightness is flexibly adjustable, i.e., dynamically variable.
The large current region corresponds to a case where the preset display luminance is higher than the dimming threshold, and the small current region corresponds to a case where the preset display luminance is lower than the dimming threshold.
As an embodiment of the present invention, the control method is a coordinated dimming method between an LCD (Liquid crystal display) panel and an LED backlight array, and solves a problem that a discrete MOS transistor is difficult to control a gray scale in a large current region. Meanwhile, in a low-current area, a dynamic dimming mode is adopted, wherein the dynamic dimming mode refers to that the LCD array and the backlight LED array are used for controlling the gray scale at the same time, the defect of backlight light leakage of a liquid crystal screen can be overcome, and the contrast of the screen is improved.
Fig. 5 shows a specific implementation flow of a backlight control method according to the present invention, and for convenience of description, only the relevant portions of the embodiment are shown, which are detailed as follows:
as an embodiment of the present invention, the step S102 further includes the following steps:
s1021, when the preset display brightness is higher than the dimming threshold, setting the brightness to be first brightness;
in one embodiment, the first light-emitting brightness is a maximum value of light-emitting brightness of a plurality of backlight lattices provided for the backlight unit. In the backlight unit, a plurality of backlight lattices are provided, and each backlight lattice is provided with a corresponding light-emission luminance, and thus, a plurality of light-emission luminances appear. The maximum value is selected among a plurality of light emission luminances, i.e., defined as a first light emission luminance, i.e., corresponding to B in fig. 4max。
And S1022, when the preset display brightness is weaker than the dimming threshold, setting the brightness to be a second brightness, and regulating and controlling the pixel gray level.
In one embodiment, the second luminance is a square root of a product of the predetermined display luminance and the predetermined luminance and a quotient of the product and the maximum backlight transmittance, which is obtained by the following formula:
B＝sqrt(L*BT/Tmax)
wherein L is the preset display brightness, BTFor presetting the brightness, TmaxSqrt is the square root for maximum backlight transmittance.
Furthermore, under the condition of lower preset display brightness, the brightness of the liquid crystal unit and the brightness of the backlight unit can be regulated and controlled simultaneously to regulate and control the gray level of the pixel, so that the problem of light leakage of liquid crystal is avoided, and very low display brightness can be realized.
The specific implementation flow of the backlight control method is as follows:
firstly, acquiring preset display brightness, and judging whether the preset display brightness is stronger than a dimming threshold value; if so, setting the brightness of the backlight unit to be first brightness which is fixed and unchanged; if not, the light-emitting brightness of the backlight unit is set to be a second light-emitting brightness which can be flexibly adjusted; and finally, according to the preset display brightness and the set luminous brightness, the preset display brightness and the set luminous brightness are subjected to division and quotient calculation to obtain the backlight transmittance of the liquid crystal unit and set the backlight transmittance.
By the backlight control method, different luminance and backlight transmissivity are correspondingly set according to the strength relation between preset display brightness and a dimming threshold, so that the problem that the gray scale of the discrete MOS tube in a large-current area is difficult to control is solved; the flexibility of this control mode is stronger, has promoted the contrast of screen, and user's experience feels stronger.
Fig. 6 shows a module structure of a backlight control system according to another embodiment of the present invention, and for convenience of description, only the relevant parts of the embodiment are shown, which are detailed as follows:
the present invention also provides a backlight control system for a liquid crystal panel, the liquid crystal panel including a backlight unit and a liquid crystal unit, the backlight control system comprising:
the display brightness judging module 10 is configured to obtain preset display brightness, and judge a strength relationship between the preset display brightness and a dimming threshold;
in an embodiment, the dimming threshold is set to be a product of a maximum backlight transmittance and a preset light emitting luminance, wherein the maximum backlight transmittance is a maximum value of the backlight transmittances in the plurality of backlight lattices provided for the liquid crystal cell. In the liquid crystal unit, a plurality of pixel points are arranged, and each pixel point is correspondingly provided with backlight transmittance, so that a plurality of backlight transmittances can appear. A maximum value is selected among the plurality of backlight transmittances, i.e., defined as a maximum backlight transmittance. Meanwhile, the preset light-emitting brightness is set by combining the demarcation point of the large-current area and the small-current area of the discrete MOS tube, namely the critical value of dynamic dimming.
A light-emitting brightness setting module 20, configured to set light-emitting brightness of the backlight unit according to a strength relationship between preset display brightness and a dimming threshold;
because the brightness of the backlight unit is set according to the strength relation between the preset display brightness and the dimming threshold, the brightness of the backlight unit can be flexibly adjusted, namely dynamically changed. Specifically, when the preset display brightness is stronger than the dimming threshold, the light-emitting brightness of the backlight unit is a fixed value, and the screen adopts the same display mode as the traditional static backlight; when the preset display brightness is weaker than the dimming threshold, the light emitting brightness of the backlight unit changes in real time with the change of the preset display brightness, and then the screen should adopt a dynamic backlight algorithm. Referring to fig. 3, the case where the preset display luminance is stronger than the dimming threshold corresponds to a large current region of the discrete MOS transistor. Meanwhile, the situation that the preset display brightness is weaker than the dimming threshold corresponds to a low-current region of the discrete MOS tube, and due to the adoption of a dynamic backlight algorithm, the brightness of the backlight unit is flexibly adjusted, the gray scale adjustment precision is greatly improved, and the problem that the discrete MOS tube is difficult to control the gray scale in the high-current region is solved.
And a backlight transmittance setting module 30, configured to set a backlight transmittance of the liquid crystal cell according to the preset display brightness and the set light emitting brightness.
Specifically, after the luminance of the backlight unit is set, the backlight transmittance of the liquid crystal unit is obtained, and the two are in an inverse proportional relationship. In this embodiment, the quotient obtained by dividing the preset display brightness value and the set brightness value is used to obtain the backlight transmittance of the liquid crystal cell and set the backlight transmittance, which is specifically obtained by the following formula:
T＝L/B
wherein, T is the backlight transmittance of the liquid crystal cell, L is the preset display brightness, and B is the set brightness.
The brightness of the backlight unit can be flexibly adjusted, so that the backlight transmissivity of the liquid crystal unit is correspondingly changed, the effect of stronger flexibility of the control method is achieved, the contrast of a screen is improved, and the user experience is stronger.
Fig. 7 shows a specific module structure of a backlight control system according to another embodiment of the present invention, and for convenience of description, only the relevant parts of the embodiment are shown, and the detailed description is as follows:
as an embodiment of the present invention, the light-emitting brightness setting module 20 further includes:
a first setting unit 201, configured to set the luminance to a first luminance when the preset display luminance is stronger than the dimming threshold;
in one embodiment, the first light-emitting brightness is a maximum value of light-emitting brightness of a plurality of backlight lattices provided for the backlight unit. In the backlight unit, a plurality of backlight lattices are provided, and each backlight lattice is provided with a corresponding light-emission luminance, and thus, a plurality of light-emission luminances appear. The maximum value is selected among the plurality of light emission luminances, that is, defined as a first light emission luminance.
The second setting unit 202 is configured to set the light-emitting brightness to a second light-emitting brightness and regulate and control the pixel grayscale when the preset display brightness is weaker than the dimming threshold.
In one embodiment, the second luminance is a square root of a product of the predetermined display luminance and the predetermined luminance and a quotient of the product and the maximum backlight transmittance. Furthermore, under the condition of lower preset display brightness, the brightness of the liquid crystal unit and the brightness of the backlight unit are regulated and controlled to regulate the gray level of the pixel, so that the problem of liquid crystal light leakage is avoided, and very low display brightness can be realized.
In one embodiment, fig. 8 shows a display unit composed of liquid crystal cells LCDi and backlight units LEDi, and the preset display luminance L thereof can be expressed as:
L＝BT EQN(3.1)
where B is the luminance of the backlight unit and T is the backlight transmittance of the liquid crystal unit. In general, in the case of a static backlight, B is a constant, the variation of the gray level of L is completely adjusted by the variation of T, and the presence of the phenomenon T (0) ≠ 0 constrains the gray level minimum value Lmin ═ B ≠ Tleak of L. In the case of a dynamic backlight, B may vary from one screen to another, and thus the minimum value of the gray scale of L may be reduced.
Therefore, according to the above formula EQN 3.1.1, in order to achieve a certain preset display luminance L, 2 degrees of freedom are involved: the luminance B and the backlight transmittance T. For example, to lower the preset display luminance L, the emission luminance B may be lowered, and the backlight transmittance T may also be lowered. The luminance B of the backlight is determined by the backlight panel, and the transmittance T of the backlight is determined by the liquid crystal panel.
When the preset display brightness L is high, the same display mode (corresponding to the large current region in fig. 4) as the conventional static backlight is used; when the preset display luminance L is low, the dynamic backlight algorithm (corresponding to the low current region in fig. 4) of the current mainstream is adopted. The boundary of high and low brightness is BTTmax, thus avoiding the difficulty of gray scale control in the high-current region of the discrete MOS tube, wherein BTTmax is the maximum backlight transmittance, which is the above-mentioned predetermined light emission luminance.
Because a plurality of pixel points are arranged in the liquid crystal unit, a plurality of backlight lattices are arranged in the backlight unit, and the following dynamic dimming modes for the condition that the number of the LED backlight lattices is the same as that of the LCD pixel points and the condition that the number of the LED backlight lattices is less than that of the LCD pixel points are described one by one:
firstly, the LED backlight dot matrix and the LCD pixel points have the same number and correspond to each other:
in the first case: if the preset display brightness L is larger, the L/Tmax is satisfied>BT. The light emission luminance B is set to Bmax at this time, which is the above-described maximum light emission luminance, so that the backlight transmittance T is set purely to realize L. Where the backlight transmittance T should be set to L/Bmax. Under the condition that the preset display brightness L is larger, the backlight transmissivity T is also larger, and at the moment T>>Tleak, the luminance error caused by light leakage is small.
In the second case: if the preset display brightness L is smaller, the L/Tmax is satisfied<＝BT. At this time, the light emission luminance B is set to sqrt (L × B)T/Tmax), and then the backlight transmittance T is set to sqrt (L × Tmax/B)T). Therefore, under the condition of lower brightness, the liquid crystal unit and the light-emitting brightness B are regulated and controlled simultaneously to regulate and control the gray level of the pixel, the problem of liquid crystal light leakage is avoided, and very low brightness can be realized. Wherein sqrt means a square root.
Specifically, B ═ sqrt (L ═ B) described in the second caseT/Tmax)，T＝sqrt(L*Tmax/BT) This is a special case, and any other combination may be adopted in practice as long as BT ═ L can be satisfied.
If it is desired to control the driving voltage VdataDigitalizing, and making it take on the value range of [ V0, V1, V2 … V ] depicted in FIG. 4T,Vmax]At this time, the corresponding light-emitting luminance is [0, B1, B2 … B ]T,Bmax]. The voltage values are mostly distributed in a small current region on a driving voltage axis, and the corresponding light-emitting brightness B1, B2 … BTThe value of the constant voltage is lower and is far less than Bmax corresponding to the maximum value Vmax of the driving voltage, namely (V-V0)/(Vmax-V0)>>B/Bmax, where V0 is the LED turn-on voltage, is equivalent to a region of low light-emitting brightness (B)<BT) Achieving a larger gray scale control range (V0-V) as much as possibleT)。
Secondly, when the number of the LED backlight dot matrixes is smaller than that of the LCD pixel points, the LED backlight dot matrixes mean that one LED backlight chip needs to illuminate N pixel points, and each pixel point corresponds to one pixel pointA liquid crystal cell. Selecting the maximum brightness value L from the display brightness L1, L2 … … LN of the N pixelsMAnd setting the brightness of the backlight unit to B ═ LMand/Tmax. Then, each Ti — Li/B, where i is 1,2 … N, is set according to the determined light emission luminance B. The following is a way of setting the light emission luminance B of the backlight unit:
in the first case: if L isMIs larger, satisfies LM/Tmax>BT. The light emission luminance B is set to Bmax at this time.
In the second case: if L isMSmaller, satisfies LM/Tmax<＝BT. The light emission luminance B is set to sqrt (L) at this timeM*BT/Tmax)。
Similarly, after the light emission luminance B is set, the backlight transmittances Ti ═ Li/B, where i is 1 and 2 … N, respectively, are set.
Fig. 9 shows a structure of a backlight control system according to another embodiment of the present invention, and for convenience of description, only the parts related to this embodiment are shown, which are detailed as follows:
the control system not only comprises a liquid crystal panel (namely a liquid crystal unit) and an LED array (namely a backlight unit), but also comprises a controller for driving the liquid crystal panel and a controller for driving the LED array. The two controllers respectively control the gray scale of each unit in the array. In this embodiment, the gray scale for both the LCD and LED arrays is 255.
The control method comprises the following steps: the backlight transmittance T and the light emission luminance B are equally divided at the time of control to distinguish the gradation. Then, let the backlight transmittance of the LCD be Tmin + n/255 x (Tmax-Tmin), where n is in the range of {0, 1,2 … 62, 63 }. The luminous brightness is m/255 Bmax, wherein the value range of m is {0, 1,2 … 14, 15, 255 }. B isTFor the dynamic dimming threshold, the threshold is also usually set as a preset luminance, specifically corresponding to the boundary point of the large current region and the small current region, in this embodiment, BT＝15/255*Bmax。
If L isMHigher than BTTmax, then the LED array controller will be LEDThe brightness of the LCD is set as Bmax, and the LCD controller respectively sets the backlight transmissivity Ti according to the requirements of each pixel point in the area.
If L isMNot higher than BTTmax, the brightness B of the LED may be set to LMand/Tmax, the LCD controller respectively sets the backlight transmissivity Ti according to the requirements of each pixel point in the area.
Therefore, in the LED backlight array unit driven in an active mode, the problem of gray scale control precision caused by the switching characteristic of the MOS tube is solved, the gray scale control capability of the backlight module is effectively improved, and especially under the condition of low gray scale, the influence of liquid crystal light leakage is reduced.
As shown in fig. 10, the present invention further provides a terminal for implementing the backlight control method, where the terminal may be a terminal such as a smart phone, a tablet computer, a Personal Computer (PC), a Personal Digital Assistant (PDA), a learning machine, and includes: one or more input devices 83 (only one shown in fig. 10) and one or more output devices 84 (only one shown in fig. 10). The processor 81, memory 82, input device 83 and output device 84 are connected by a bus 85.
It should be understood that, in the embodiment of the present invention, the Processor 81 may be a Central Processing Unit (CPU), and the Processor may also be other general processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) or other Programmable logic devices, discrete Gate or transistor logic devices, discrete hardware components, and the like. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The input device 83 may include a keyboard, a touch pad, a fingerprint sensor (for collecting fingerprint information of a user and direction information of the fingerprint), a microphone, etc., and the output device 84 may include a display, a speaker, etc.
The memory 82 may include a read-only memory and a random access memory, and provides instructions and data to the processor 81. A portion or all of the memory 81 may also include non-volatile random access memory. For example, the memory 82 may also store device type information.
The memory 82 stores a computer program that is executable on the processor 81, for example, a program of a backlight control method. The processor 81 implements the steps in the above-described embodiment of the backlight control method, such as steps 101 to 103 shown in fig. 1, when executing the computer program. Alternatively, the processor 81 executes the computer program to realize the functions of the modules/units in the backlight control system embodiment, such as the functions of the modules 10 to 30 shown in fig. 6.
The computer program may be divided into one or more modules/units, which are stored in the memory 82 and executed by the processor 81 to accomplish the present invention. The one or more modules/units may be a series of computer program instruction segments capable of performing specific functions, which are used to describe the execution process of the computer program in the terminal performing backlight control. For example, the computer program may be divided into a display brightness determination module, a light emission brightness setting module, and a backlight transmittance setting module, and the specific functions of each module are as follows: the display brightness judging module is used for acquiring preset display brightness and judging the strength relation between the preset display brightness and a dimming threshold; the light-emitting brightness setting module is used for setting the light-emitting brightness of the backlight unit according to the strength relation between the preset display brightness and the dimming threshold; and the backlight transmittance setting module is used for setting the backlight transmittance of the liquid crystal unit according to the preset display brightness and the set light-emitting brightness.
To sum up, the backlight control method, the backlight control system, the terminal and the computer-readable storage medium provided by the embodiments of the present invention are used for a liquid crystal display, where the liquid crystal display includes a backlight unit and a liquid crystal unit, and the relationship between the preset display brightness and a dimming threshold is determined by obtaining the preset display brightness; setting the brightness of the backlight unit according to the strength relation between the preset display brightness and the dimming threshold; and further setting the backlight transmittance of the liquid crystal unit according to the preset display brightness and the set light-emitting brightness. Therefore, different luminance and backlight transmittance are correspondingly set according to the strength relation between the preset display brightness and the dimming threshold, and the problem of difficulty in gray control of a large-current area of the discrete MOS tube is solved; the control mode has high flexibility, improves the contrast of a screen, and solves the problem that the gray level adjustment precision is low in the existing control technology for the dynamic backlight liquid crystal screen.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (11)
1. A backlight control method for a liquid crystal panel including a backlight unit and a liquid crystal unit, the backlight control method comprising:
acquiring preset display brightness, and judging the strength relation between the preset display brightness and a dimming threshold;
setting the brightness of the backlight unit according to the strength relation between the preset display brightness and the dimming threshold;
and setting the backlight transmissivity of the liquid crystal unit according to the preset display brightness and the set light-emitting brightness.
2. The backlight control method of claim 1, wherein setting the brightness of the backlight unit according to the relationship between the preset display brightness and the dimming threshold specifically comprises:
when the preset display brightness is higher than the dimming threshold, setting the light-emitting brightness to be a first light-emitting brightness;
and when the preset display brightness is weaker than the dimming threshold, setting the light-emitting brightness to be a second light-emitting brightness, and regulating and controlling the pixel gray scale.
3. The backlight control method of claim 2, wherein setting the brightness of the backlight unit according to the relationship between the preset display brightness and the dimming threshold further comprises:
establishing a curve model of the luminance of the backlight unit and a driving voltage, wherein the driving voltage is used for driving the liquid crystal screen;
dividing the curve model into a large current area and a small current area according to the slope of the curve;
and setting the luminous brightness corresponding to the boundary point of the large current region and the small current region as preset luminous brightness.
4. The backlight control method of claim 3, wherein dividing the curve model into a large current region and a small current region according to a slope of the curve specifically comprises:
when the slope of the curve is larger than a preset angle value, dividing a corresponding area into the large-current area;
when the slope of the curve is smaller than the preset angle value, dividing the corresponding area into the small current area, and correspondingly acquiring the gray-scale value of the luminous brightness in the small current area according to the change of the driving voltage.
5. The backlight control method of claim 2, wherein the first light emission luminance is a maximum value of the light emission luminances in a plurality of backlight lattices provided to the backlight unit.
6. The backlight control method of claim 3, wherein the dimming threshold is a product of a maximum backlight transmittance and the preset light emission luminance,
the maximum backlight transmittance is the maximum value of the backlight transmittance among a plurality of pixel points arranged in the liquid crystal unit.
7. The backlight control method of claim 6, wherein the second light emission luminance is a square root of a product of the predetermined display luminance and the predetermined light emission luminance and a quotient of the maximum backlight transmittance.
8. The backlight control method of claim 1, wherein setting the backlight transmittance of the liquid crystal cell according to the preset display luminance and the set light emission luminance is specifically obtained according to the following formula:
T＝L/B
wherein T is the backlight transmittance of the liquid crystal unit, L is the preset display brightness, and B is the set light-emitting brightness.
9. A backlight control system for a liquid crystal panel, the liquid crystal panel including a backlight unit and a liquid crystal unit, the backlight control system comprising:
the display brightness judging module is used for acquiring preset display brightness and judging the strength relation between the preset display brightness and a dimming threshold;
the light-emitting brightness setting module is used for setting the light-emitting brightness of the backlight unit according to the strength relation between the preset display brightness and the dimming threshold;
and the backlight transmittance setting module is used for setting the backlight transmittance of the liquid crystal unit according to the preset display brightness and the set light-emitting brightness.
10. A terminal comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that the processor implements the steps of the backlight control method according to any of claims 1 to 8 when executing the computer program.
11. A computer-readable storage medium, in which a computer program is stored which, when being executed by a processor, carries out the steps of the backlight control method according to any one of claims 1 to 8.
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