WO2017096567A1 - 背光电路、电子设备及背光调节方法 - Google Patents

背光电路、电子设备及背光调节方法 Download PDF

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Publication number
WO2017096567A1
WO2017096567A1 PCT/CN2015/096869 CN2015096869W WO2017096567A1 WO 2017096567 A1 WO2017096567 A1 WO 2017096567A1 CN 2015096869 W CN2015096869 W CN 2015096869W WO 2017096567 A1 WO2017096567 A1 WO 2017096567A1
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WIPO (PCT)
Prior art keywords
resistance
branch
backlight
duty ratio
resistor
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PCT/CN2015/096869
Other languages
English (en)
French (fr)
Inventor
帅俊卿
张浩靖
褚建飞
王石磊
Original Assignee
华为技术有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to CN201580071170.1A priority Critical patent/CN107533827B/zh
Priority to PCT/CN2015/096869 priority patent/WO2017096567A1/zh
Priority to EP15910042.9A priority patent/EP3376493B8/en
Priority to KR1020187019390A priority patent/KR102115873B1/ko
Priority to US16/060,442 priority patent/US10499472B2/en
Priority to JP2018529963A priority patent/JP6606288B2/ja
Publication of WO2017096567A1 publication Critical patent/WO2017096567A1/zh

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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
    • 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
    • G09G3/36—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 using liquid crystals
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/10—Controlling the intensity of the light
    • H05B45/12—Controlling the intensity of the light using optical feedback
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/06—Adjustment of display parameters
    • G09G2320/0626—Adjustment of display parameters for control of overall brightness
    • G09G2320/0633—Adjustment of display parameters for control of overall brightness by amplitude modulation of the brightness of the illumination source
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/06—Adjustment of display parameters
    • G09G2320/0626—Adjustment of display parameters for control of overall brightness
    • G09G2320/064—Adjustment of display parameters for control of overall brightness by time modulation of the brightness of the illumination source

Definitions

  • Embodiments of the present invention relate to the field of liquid crystal display, and in particular, to a backlight circuit, an electronic device, and a backlight adjustment method.
  • LCD Liquid Crystal Display
  • the LCD needs to use a backlight circuit to provide backlighting for proper display.
  • the backlight circuit is controlled by a backlight controller.
  • the backlight circuit comprises: a backlight power chip and a backlight LED connected to the backlight power chip (English: Light Emitting Diode, referred to as LED).
  • the backlight power chip receives the pulse width modulation (Pulse-Width Modulation, PWM for short) signal sent by the backlight controller, and the backlight power chip outputs a driving current to the backlight LED according to the pulse width modulation signal, and the backlight LED is driven according to the driving.
  • the current is backlit.
  • the magnitude of the driving current is positively correlated with the intensity of the backlight, that is, the larger the driving current, the higher the backlight intensity; the smaller the driving current, the lower the backlight intensity.
  • the current of the driving current output by the backlight power chip is limited, and the backlight brightness of the backlight LED output is also limited to a limited brightness range.
  • the minimum brightness or maximum brightness of the backlight LED output is not the ideal brightness that the developer would expect when designing or the ultimate brightness that the backlight LED can actually output.
  • the backlight power supply chip can only output the driving current within a limited current value adjustment range, and the brightness of the backlight LED output also belongs to the limited brightness range.
  • a backlight circuit, an electronic device, and a backlight adjustment method is as follows:
  • an embodiment of the present invention provides a backlight circuit, including: a backlight power chip and an adjustable resistor circuit;
  • the backlight power chip includes: a setting pin and an input pin for setting a reference current. And an output pin; one end of the adjustable resistance circuit is connected to the setting pin, The other end of the adjustable resistance circuit is grounded, the adjustable resistance circuit includes a first resistance branch and a second resistance branch, and the first resistance branch and the second resistance branch have different resistance values And for generating different reference currents;
  • the adjustable resistance circuit includes: a control end, wherein the control end is configured to receive a switching signal, and the resistance branch connected to the setting pin is in accordance with the switching signal Switching between the first resistor branch and the second resistor branch; the backlight power chip for determining a duty ratio of the PWM signal received according to the input pin based on the reference current Generating a drive current; outputting the drive current through the output pin, the drive current being used to drive a backlight source to transmit a backlight.
  • the backlight circuit provided by the first aspect is connected to the adjustable resistor circuit by the setting pin of the backlight power chip, and the adjustable resistor circuit connects the resistor branch connected to the set pin according to the switching signal at the first resistor branch and Switching between the second resistor branches, thereby changing the reference current in the backlight power chip, since the driving current is generated based on the reference current, thereby changing the current value adjustment range of the driving current; solving the limitation of the backlight power chip Hardware performance, the backlight power chip can only output the drive current within a limited current value adjustment range, resulting in the brightness of the backlight source output also falling into the finite brightness range; the reference current in the backlight power supply is changed through different resistance branches, thereby The output drive current is output within a larger current value adjustment range, so that the backlight intensity reaches a lower brightness or higher brightness effect.
  • the adjustable resistance circuit includes: a selection switch and at least two resistance branches; and any one of the at least two resistance branches is the a first resistance branch, the other one of the at least two resistance branches being the second resistance branch; the selection switch comprising: the control end and the selection end; And switching a resistance branch connected to the setting pin between the first resistance branch and the second resistance branch according to the switching signal received by the control terminal.
  • the selection switch comprising: the control end and the selection end; And switching a resistance branch connected to the setting pin between the first resistance branch and the second resistance branch according to the switching signal received by the control terminal.
  • the adjustable resistance circuit includes a first resistor and a second resistor connected in series; the first resistor and the second a resistor forming the first resistor branch; the second resistor forming the second resistor branch; or, the first resistor and the second resistor forming the second resistor branch; A resistor forms the first resistance branch.
  • the resistance branch in the adjustable resistance circuit is realized by the series circuit, and the electric The form of the road is simple and easy to design and produce on the circuit board.
  • the adjustable resistance circuit includes a third resistor and a fourth resistor connected in parallel; the third resistor forms the first a resistor branch; the fourth resistor forms the second resistor branch.
  • the resistance branch in the adjustable resistance circuit is realized by the parallel circuit, and the circuit form is simple and easy to design and produce on the circuit board.
  • the switching signal is sent by the backlight controller when the resistance branch corresponding to the desired brightness value and the resistance branch connected to the setting pin are different; the desired brightness value is used to indicate that the backlight source is desired to be emitted Backlight brightness.
  • an embodiment of the present invention provides an electronic device, including: a backlight controller, a memory, a backlight circuit according to any one of the first aspect or the first aspect, and a backlight source; the memory being coupled to the backlight controller, the memory storing an executable program of the backlight controller;
  • the backlight controller is connected to the input pin in the backlight circuit for transmitting the PWM signal to the backlight power chip; the backlight controller is connected to the control terminal in the backlight circuit And transmitting the switching signal to the adjustable resistance circuit;
  • the output pin of the backlight power chip in the backlight circuit is connected to the backlight source; the backlight source is configured to emit a backlight according to the driving current.
  • the backlight controller is: a central processing unit (English: Central Processing Unit; CPU); or the backlight controller 220 is a graphics processor (English: Graphics) The processing unit (abbreviation: GPU); or, the backlight controller 220 is an LCD driver integrated circuit (English: Driver integrated circuit, referred to as: Drive IC).
  • a central processing unit English: Central Processing Unit; CPU
  • the backlight controller 220 is a graphics processor (English: Graphics)
  • the processing unit abbreviation: GPU
  • the backlight controller 220 is an LCD driver integrated circuit (English: Driver integrated circuit, referred to as: Drive IC).
  • the backlight controller is configured to execute instructions in the memory, the backlight controller implementing any one of the following third or third aspects by executing the instructions The backlight adjustment method provided by the implementation.
  • an embodiment of the present invention provides a backlight adjustment method, which is applied to a backlight controller of an electronic device provided by the second aspect, the method comprising: the backlight controller acquiring a desired brightness value, the desired brightness a value for indicating a brightness of a backlight that is desired to be emitted by the backlight source; the backlight controller determining a resistance branch corresponding to the desired brightness value, the resistance branch being the first resistance branch and One of the second resistance branches; the backlight controller is directed to the adjustable resistance circuit when a resistance branch corresponding to the desired brightness value and a resistance branch connected to the set pin are different
  • the control terminal sends a switching signal; the backlight controller sends a PWM signal to the backlight power chip, the duty ratio of the PWM signal corresponds to the desired brightness value; and the backlight power chip is configured to use the reference current as a reference, generating a driving current according to a duty ratio of the PWM signal, and transmitting the driving current to the backlight source, wherein the backlight source is
  • the backlight adjustment method provided by the third aspect, by obtaining a desired brightness value by the backlight controller, controlling the adjustable resistance circuit when the resistance branch corresponding to the desired brightness value and the resistance branch connected to the set pin are different
  • the terminal sends a switching signal, and the adjustable resistor circuit switches the resistor branch connected to the set pin between the first resistor branch and the second resistor branch according to the switching signal, thereby changing the reference current in the backlight power chip, because The driving current is generated based on the reference current, so the current value adjustment range of the driving current is further changed; the backlight power supply chip can only output the driving current within a limited current value adjustment range due to the hardware performance of the backlight power supply chip.
  • the brightness of the backlight source output is also a problem of limited brightness range; the reference current in the backlight power supply is changed by different resistance branches, so that the output current is outputted within a larger current value adjustment range, so that the backlight intensity is lower.
  • the effect of brightness or higher brightness is also a problem of limited brightness range; the reference current in the backlight power supply is changed by different resistance branches, so that the output current is outputted within a larger current value adjustment range, so that the backlight intensity is lower.
  • the effect of brightness or higher brightness is also a problem of limited brightness range; the reference current in the backlight power supply is changed by different resistance branches, so that the output current is outputted within a larger current value adjustment range, so that the backlight intensity is lower.
  • the method before the sending the switching signal to the control end of the adjustable resistance circuit, the method further includes: if the resistance branch connected to the setting pin is the first When the resistance branch and the resistance of the first resistor branch are greater than the resistance of the second resistor branch, the duty ratio of the currently output PWM signal is gradually increased to a maximum duty ratio of 1 , the maximum The ratio 1 is the maximum duty ratio when the set pin is connected to the first resistor branch; if the resistor branch connected to the set pin is the first resistor branch and the first When the resistance of the resistance branch is smaller than the resistance of the second resistance branch, the duty ratio of the currently output PWM signal is gradually reduced to a minimum duty ratio of 1 , the minimum duty ratio 1 being the setting a minimum duty ratio when the pin is connected to the first resistor branch; if the resistor branch connected to the set pin is the second resistor branch and the resistance of the first resistor branch is greater than When the resistance of the second resistor branch is reduced, the duty ratio of the currently output PWM signal is
  • the sending by the backlight power supply chip, a PWM signal, where a duty ratio of the PWM signal corresponds to the desired brightness value, including: querying and the desired brightness value Corresponding to the duty ratio; after the switching, the resistance branch connected to the setting pin is the second resistance branch and the resistance of the first resistance branch is greater than the second resistance branch
  • the PWM signal currently outputted is gradually increased from the minimum duty ratio 2 to the duty ratio, and the minimum duty ratio 2 is when the setting pin is connected to the second resistance branch a minimum duty ratio
  • a resistance branch connected to the set pin after switching is the second resistor branch and a resistance of the first resistor branch is smaller than a resistance of the second resistor branch
  • gradually decreasing the currently outputted PWM signal from a maximum duty ratio 2 to the duty ratio, where the maximum duty ratio 2 is when the set pin is connected to the second resistance branch a maximum duty ratio
  • a resistance branch connected to the set pin after switching is the first resistance branch When the resistance of the first resist
  • the maximum duty ratio 1 is a maximum duty ratio when the set pin is connected to the first resistor branch; after the switching, the resistor branch connected to the set pin is the first resistor branch And when the resistance of the first resistor branch is smaller than the resistance of the second resistor branch, the minimum duty ratio 1 of the currently outputted PWM signal is gradually increased to the duty ratio,
  • the minimum duty cycle 1 is the minimum duty cycle when the set pin is connected to the first resistive branch.
  • the PWM signal can be gradually changed after the switching signal is transmitted, and the sudden change in the backlight luminance is not caused, and the flicker phenomenon of the backlight luminance is avoided.
  • the resistance value R1 of the first resistance branch and the resistance value R2 of the second resistance branch satisfy the following conditions:
  • the minimum duty ratio 1 is a minimum duty ratio when the set pin is connected to the first resistor branch; the maximum duty ratio 1 is the set pin and the first resistor a maximum duty ratio when the branches are connected; the minimum duty ratio 2 is a minimum duty ratio when the set pin is connected to the second resistance branch; the maximum duty ratio 2 is the setting The maximum duty cycle when the pin is connected to the second resistor branch.
  • the first resistance branch can be made to correspond
  • the current value adjustment range and the current value adjustment range corresponding to the second resistance branch can be combined into one continuous current value adjustment range, thereby realizing a wide range of current value adjustment range.
  • the current value adjustment range in which the variation range is large is such that there is no flicker when switching between the first resistance branch and the second resistance branch.
  • 1 is a schematic structural view of an existing electronic device
  • FIG. 2 is a schematic structural diagram of an electronic device according to an embodiment of the present invention.
  • 3A is a schematic structural diagram of an adjustable resistance circuit according to an embodiment of the present invention.
  • FIG. 3B is a schematic structural diagram of an adjustable resistance circuit according to another embodiment of the present invention.
  • 3C is a schematic structural diagram of an adjustable resistance circuit according to another embodiment of the present invention.
  • FIG. 4 is a schematic structural diagram of an electronic device according to an embodiment of the present invention.
  • FIG. 5 is a schematic diagram of the principle of the electronic device shown in FIG. 4 when performing backlight adjustment
  • FIG. 6 is a flowchart of a backlight adjustment method according to an embodiment of the present invention.
  • FIG. 7A is a flowchart of a backlight adjustment method according to an embodiment of the present invention.
  • FIG. 7B is a flowchart of a backlight adjustment method according to an embodiment of the present invention.
  • FIG. 7C is a flowchart of a backlight adjustment method according to an embodiment of the present invention.
  • FIG. 7D is a flowchart of a backlight adjustment method according to an embodiment of the present invention.
  • FIG. 1 shows a schematic structural diagram of an existing electronic device 100 .
  • the electronic device 100 includes a backlight controller 120, a memory 140, a backlight power chip 160, and a backlight source 180.
  • the backlight controller 120 can be a central processing unit (English: Central Processing Unit; referred to as: The backlight controller 120 may also be a graphics processing unit (English: Graphics Processing Unit, GPU for short); or the backlight controller 120 may also be an LCD integrated circuit (English: Driver integrated circuit, referred to as: Drive) IC).
  • the backlight controller 120 may also be a graphics processing unit (English: Graphics Processing Unit, GPU for short); or the backlight controller 120 may also be an LCD integrated circuit (English: Driver integrated circuit, referred to as: Drive) IC).
  • the memory 140 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (English: Static Random Access Memory, SRAM), electrically erasable programmable read only Memory (English: Electrically Erasable Programmable Read-Only Memory, EEPROM for short), Erasable Programmable Read Only Memory (EPROM), Programmable Read Only Memory (English: Programmable Read- Only Memory (referred to as: PROM), read only memory (English: Read Only Memory, referred to as: ROM), magnetic memory, flash memory, disk or optical disk.
  • static random access memory English: Static Random Access Memory, SRAM
  • electrically erasable programmable read only Memory English: Electrically Erasable Programmable Read-Only Memory, EEPROM for short
  • EPROM Erasable Programmable Read Only Memory
  • PROM Programmable Read Only Memory
  • ROM Read Only Memory
  • magnetic memory magnetic memory
  • flash memory disk or optical disk.
  • the backlight power chip 160 is an integrated circuit chip that outputs a driving current based on a PWM signal.
  • the backlight power chip 160 includes an input pin IN, a set pin ISET, and an output pin OUT.
  • the interior of the backlight power chip 160 includes a reference current source circuit 162.
  • the input pin IN is connected to the backlight controller 120.
  • the set pin ISET is connected to the reference current source circuit 162 inside the backlight power chip 160.
  • the set pin ISET is also connected to one end of the resistor R ISET outside the backlight power chip 160, and the other end of the resistor R ISET is grounded.
  • the reference current source circuit 162 is for providing a reference current I FB_full , which is calculated by:
  • I FB_full V ISET_full /R ISET *K ISET_full Formula One
  • V ISET_full is a reference voltage with a fixed voltage value
  • K ISET_full is a fixed parameter
  • K ISET_full is determined by electrical properties of the electronic components in the reference current source circuit 162.
  • one pin of the backlight power chip 160 is connected to the power source VBAT, and the other pin is grounded.
  • Backlight source 180 is typically a backlight LED. One end of the backlight source 180 is connected to the power source VBAT, and the other end is connected to the input pin OUT in the backlight power chip 160.
  • backlight controller 140 In operation, backlight controller 140 generates a desired brightness value in accordance with a predetermined backlight control strategy.
  • the desired brightness value is the backlight brightness that the backlight controller 120 desires from the backlight source 180.
  • the predetermined backlight control strategy is: when the ambient light level is dimmed, the desired brightness value is lowered; in the ambient light When the degree is bright, increase the desired brightness value.
  • the desired luminance value is typically represented by a 9-bit or 11-bit binary number and stored in a backlight register Reg_Iset.
  • the 9-bit representation is taken as an example, and the desired luminance value is 000000000, that is, 0 in decimal; or, the desired luminance value is 111111111, that is, 511 in decimal.
  • the expected brightness value is only a schematic mode of the brightness level or the brightness level, and is not equivalent to the brightness value in the actual physical quantity.
  • the backlight controller 140 queries the duty ratio corresponding to the desired luminance value in the "expected luminance value - duty ratio" correspondence table stored in advance.
  • This "expected brightness value - duty ratio” correspondence table is stored in the memory 140.
  • Table 1 exemplarily shows a "expected luminance value - duty ratio” correspondence table.
  • the desired brightness values are expressed in decimal below.
  • the backlight controller 140 transmits a PWM signal conforming to the duty ratio to an input pin of the backlight power chip 160. For example, if the brightness value is desired to be 4, the backlight controller 140 transmits a PWM signal having a duty ratio of 1.76% to the input pin of the backlight power chip 160.
  • the backlight power chip 160 After receiving the PWM signal, the backlight power chip 160 generates a driving current according to the duty ratio of the PWM signal based on the reference current.
  • the magnitude of the current of the drive current is proportional to the duty cycle of the PWM signal.
  • the current value of the drive current is calculated as follows:
  • I FB_full is the reference current and Duty is the duty cycle.
  • the duty cycle of the PWM signal is 1%
  • the reference current is 20mA
  • the duty ratio of the PWM signal is 100%
  • the minimum duty cycle that the backlight power chip 160 can receive is about 1%, so the minimum driving current that the backlight power chip 160 can output is approximately equal to: 1%* reference current, maximum
  • the driving current is approximately equal to: 100%* reference current, that is, the current value adjustment range of the driving current is [1%*I FB_ful , 100%*I FB_ful ].
  • the current value adjustment range is [ 2mA, 20mA]. Obviously, the current value adjustment range is limited.
  • the current value adjustment range of the driving current is relatively limited, in some dark light conditions, even if the backlight source 180 is driven with the minimum driving current, the backlight of the backlight power source 180 is still very strong, thereby irritating the user's eyes. Similarly, under certain bright conditions, even if the maximum driving current is used to drive the backlight source 180, the backlight emitted by the backlight power source 180 is still weak, and the display content on the liquid crystal display cannot be seen.
  • the maximum number of adjustment steps in the current value adjustment range is 512 steps, and the current value change of the drive current between the adjacent two backlight brightness values is about 0.19%* reference current.
  • the current value of the driving current is related to the reference current.
  • the embodiment of the present invention provides a technical solution based on changing the reference current to obtain a driving current having a larger current value range.
  • FIG. 2 a schematic structural diagram of an electronic device 200 according to an embodiment of the present invention is shown.
  • the backlight controller 220 may be a central processing unit (English: Central Processing Unit; abbreviated as: CPU); or the backlight controller 220 may also be a graphics processing unit (English: Graphics Processing Unit, GPU for short); or, a backlight controller 220 can also be an LCD driver integrated circuit (English: Driver integrated circuit, referred to as: Drive IC).
  • CPU Central Processing Unit
  • GPU Graphics Processing Unit
  • a backlight controller 220 can also be an LCD driver integrated circuit (English: Driver integrated circuit, referred to as: Drive IC).
  • Executable instructions of the backlight controller 220 are stored in the memory 240.
  • the memory 240 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), electrically erasable and programmable.
  • SRAM Static Random Access Memory
  • Read-only memory English: Electrically Erasable Programmable Read-Only Memory, EEPROM for short
  • EPROM Erasable Programmable Read Only Memory
  • PROM Programmable Read Only Memory
  • Read Only Memory English: Read Only Memory, ROM
  • magnetic memory flash memory, disk or optical disk.
  • the backlight power chip 260 includes an input pin IN, a setting pin ISET for setting a reference current, and an output pin OUT.
  • the interior of the backlight power chip 260 further includes a reference current source circuit 262.
  • the input pin IN is connected to the backlight controller 220.
  • backlight controller 220 is operative to transmit a PWM signal to input pin IN.
  • the adjustable resistance circuit 270 includes a first resistance branch 272 and a second resistance branch 274.
  • the resistance of the first resistor branch 272 is different from the resistance of the second resistor branch 274. It should be noted that although FIG. 2 shows the first resistance branch 272 and the second resistance branch 274, this does not constitute a limitation on the number thereof.
  • Figure 3A also shows a plurality of resistive branches including other resistive branches.
  • the adjustable resistance circuit 270 includes a control terminal C1.
  • the control terminal C1 is connected to the backlight controller 220.
  • the backlight controller 220 is configured to send a switching signal to the control terminal C1 when it is required to change the adjustment range of the driving current.
  • the control terminal C1 is configured to receive a switching signal, and the resistance branch connected to the setting pin ISET is switched from the first resistance branch 272 to the second resistance branch 274 according to the switching signal. Since the backlight power supply chip 260 includes a reference current source circuit 262, the reference current source circuit is used to provide a reference current 262. When the resistance of the resistor branch connected to the set pin ISET changes, the current value of the reference current in the backlight power chip 260 also changes. The magnitude of the reference current is inversely proportional to the resistance of the resistor branch connected to the set pin ISET.
  • the output pin OUT in the backlight power chip 220 is connected to one end of the backlight source 460.
  • Backlight power supply 460 is typically a backlight LED.
  • the other end of the backlight source 460 is connected to the power source VBAT.
  • the backlight power chip 260 and the adjustable resistor circuit 270 may be integrated on a motherboard of the electronic device, and the motherboard is usually further provided with a backlight controller 220, a memory 240, and other electronic devices.
  • the backlight power chip 260 is an integrated circuit chip disposed on the motherboard.
  • the backlight power chip 260 is electrically connected to the adjustable resistor circuit 270 through a conductive line on the main board.
  • the set pins ISET may have different names in different embodiments, such as full scale setting pins, but are all pins for setting the reference current. This embodiment sets the pin ISET The name is not specifically limited.
  • the adjustable resistance circuit 270 includes a selection switch 271, a first resistance branch 272, and a second resistance branch 274.
  • the selection switch 271 includes a control terminal C1 and a selection terminal C2.
  • the control terminal C1 is used to be connected to the backlight controller 220.
  • the selection terminal C2 is configured to connect the setting pin ISET with one of the first resistance branch 272 and the second resistance branch 272 according to the switching signal received by the control terminal C1.
  • the selection terminal C2 connects the setting pin ISET with the resistance branch having a smaller resistance value according to the switching signal received by the control terminal C1, so that the current value of the reference current in the backlight power source chip 220 is obtained.
  • the selection terminal C2 is set according to the switching signal received by the control terminal C1.
  • the pin ISET is connected to the resistor branch having a large resistance value, so that the current value of the reference current in the backlight power chip 270 is a small current value, thereby outputting a smaller driving current under the same duty ratio condition, thereby obtaining more Low backlight brightness.
  • control terminal C1 is a control terminal C1 that conforms to a general standard input output (English: General Purpose Input Output, GPIO for short).
  • the resistance branches in the adjustable resistance circuit 270 are two. However, three, four or even more can be set according to the requirements of the embodiment.
  • the number of the resistor branches in the adjustable resistor circuit 270 is not limited in this embodiment.
  • the adjustable resistance circuit 270 is implemented by an integrated variable resistance device.
  • the resistor branch in the adjustable resistance circuit 270 is implemented by a series circuit or a parallel circuit.
  • the adjustable resistance circuit 270 includes: a selection switch 271, a first resistor R ISET1 and a second resistor R ISET2 connected in series;
  • the first resistor R ISET1 and the second resistor R ISET2 form a second resistance branch 274; the second resistor R ISET2 forms a first resistance branch 272.
  • the second end of resistor R ISET2 provided ISET pin connected to the other end of the second resistor connected to one end of the first resistor R ISET2 R ISET1, the other end of the first resistor R ISET1.
  • the setting pin ISET is connected to the second resistance branch 274; when the selection terminal C2 in the selection switch 271 is turned on, the setting pin is set.
  • the ISET is connected to the first resistor branch 272.
  • the adjustable resistance circuit 270 includes a selection switch 271, a third resistor R ISET1 and a fourth resistor R ISET2 connected in parallel;
  • the third resistor R ISET1 forms a first resistive branch 272; the fourth resistor R ISET2 forms a second resistive branch 274.
  • the third resistor R ISET1 and the fourth resistor R ISET2 have different resistance values .
  • one ends of the third resistor R ISET1 and the fourth resistor R ISET2 are grounded.
  • the other ends of the third resistor R ISET1 and the fourth resistor R ISET2 are connected to the set terminal ISET through the selection terminal C2 of the selection switch 271.
  • the setting pin ISET is connected to the first resistance branch 272; the selection terminal and the fourth selection switch 271
  • the resistor R ISET2 is connected, the set pin ISET is connected to the second resistor branch 274.
  • adjustable resistance circuit 270 can be implemented. Only two implementations of the adjustable resistance circuit 270 are shown schematically in this embodiment, but the specific implementation of the adjustable resistance circuit 270 is not limited.
  • a current value adjustment range shown in FIG. 1 is [ The minimum duty ratio *I FB_ful , the maximum duty ratio *I FB_ful ] becomes two current value adjustment ranges [minimum duty ratio 1 *I 1 , maximum duty ratio 1 *I 1 ] and [minimum duty ratio 2 *I 2 , maximum duty ratio 2 *I 2 ].
  • I 1 is a reference current when the pin ISET is connected to the first resistor branch 272
  • I 2 is a reference current when the pin ISET is connected to the second resistor branch 274.
  • V ISET_full 1.229V
  • K ISET_full 1030
  • R 1 6340K
  • R 2 63.4K.
  • the current value adjustment range corresponding to the first resistance branch 272 is [0.002 mA, 0.2 mA]
  • the current value adjustment range corresponding to the second resistance branch 274 is [0.2 mA, 20 mA].
  • the three correspondence tables can be stored in the memory 240.
  • the three correspondence tables are: a total correspondence table between the desired luminance value and the sub-table luminance value, a first "sub-table luminance value - duty ratio" correspondence table, and a second "sub-table luminance value - duty ratio” Correspondence table.
  • the first “sub-table luminance value-duty ratio” correspondence table may be simply referred to as a first correspondence table; and the second “sub-table luminance value-duty ratio” correspondence table may be simply referred to as a second correspondence table.
  • the correspondence table is only for explaining the correspondence, and the expression of the correspondence table is not limited to the table.
  • three correspondence tables are used in this embodiment for convenience of understanding and explanation, but do not constitute a limitation on the number thereof.
  • the three correspondence tables may also be integrated on one table.
  • the total correspondence table between the expected brightness value and the sub-table brightness value may be simply referred to as a summary table.
  • the expected brightness value in a part of the expected brightness value in the total table corresponds to the sub-table brightness value in the first correspondence table, that is, the desired brightness value in a part of the value interval corresponds to the first resistance branch
  • the expected brightness value in another part of the desired brightness value in the total table corresponds to the sub-table brightness value in the second correspondence table, that is, the desired brightness value and the second resistance in the other part of the value interval
  • the branch corresponds.
  • Table 2 The schematic summary table is shown in Table 2:
  • sub-table luminance value a desired value of the desired luminance value / 255 * 511; when the desired luminance value is 256 to 511, corresponding to the second resistance branch, and the correspondence between the desired luminance value and the luminance value of the sub-table in the second correspondence table
  • sub-table brightness value (expected brightness value -256) / 255 * 511 rounded value.
  • the first correspondence table is a table of the sub-table luminance value-duty ratio actually used when the setting pin ISET in the backlight power chip 260 is connected to the first resistance branch.
  • An illustrative first correspondence table is shown in Table 3.
  • the second "expected brightness value - duty ratio" correspondence table may be simply referred to as a second correspondence table.
  • Second correspondence table When the setting pin in the backlight power chip 220 is connected to the second resistor branch, the "expected brightness value - duty ratio" correspondence table is required.
  • An illustrative second correspondence table is shown in Table 4.
  • the backlight controller 220 When the electronic device 200 is powered on, the backlight controller 220 reads the default desired brightness value (a pre-configured value or a value at the time of the last shutdown) from the backlight register Reg_Iset.
  • the desired brightness value is 259
  • the desired brightness value 259 corresponds to the sub-table brightness value 6 in the second correspondence table in the summary table, that is, the desired brightness value 259 corresponds to the second resistance branch 274.
  • the backlight controller 220 controls the second resistor branch 274 in the adjustable resistor circuit 270 to be connected to the set pin ISET.
  • the backlight controller 220 queries the second correspondence table for the duty ratio corresponding to the sub-table brightness value 6 to be 2.14%, and the backlight controller 220 sends the duty ratio to the input pin IN of the backlight power chip 260 to be 2.14. % PWM signal.
  • the reference current in the backlight power chip 260 is 20 mA
  • the backlight source 280 outputs the backlight to the outside according to the driving current of 4.28 mA.
  • the user manually sets the desired brightness value to be changed
  • An adjustment control for backlight brightness is provided in the setting interface of the electronic device.
  • the adjustment control is typically a drag adjustment control that includes a button 420 and a drag bar 440, as shown in FIG. The user moves the different positions of the drag bar 440 by dragging the button 420 to effect a change in the desired brightness value.
  • the application changes the desired brightness value according to its own control logic
  • the adjustment of the desired brightness value by the backlight controller 220 belongs to the control of the operating system level, in the operating system There is also an application layer on the system.
  • the application runs various applications, such as instant messaging programs, e-book readers, telephone programs, and short message programs.
  • the application changes the desired brightness value according to its own control logic. For example, the application is an e-book reading degree, and in the night reading mode, the desired brightness value is changed to 50; for example, the application is a telephone program, and in the call mode, the desired brightness value is changed to 0.
  • the operating system changes the desired brightness value based on the ambient light intensity.
  • a light sensor is usually disposed on the electronic device, and the ambient light intensity is collected by the light sensor.
  • the operating system can change the desired brightness value according to the ambient light intensity, for example, setting the desired brightness value to 100 when the ambient light intensity is A, and setting the desired brightness value to 200 when the ambient light intensity is B.
  • the manner in which the desired luminance value is changed in this embodiment is not limited.
  • the default desired brightness value 259 is manually modified by the user to 258.
  • the backlight controller 220 queries the total table that the sub-table brightness value corresponding to the desired brightness value 258 is 4 in the second correspondence table, that is, the resistance branch corresponding to the desired brightness value 258 is the second resistance branch 274. . Since the second resistor branch 274 is connected to the set pin ISET at this time, switching is not required.
  • the backlight controller 220 queries the second correspondence table that the duty ratio corresponding to the sub-table brightness value 4 is 1.76%, and the backlight controller 220 sends the duty ratio to the input pin IN of the backlight power chip 260 to be 1.76%. PWM signal.
  • the reference current in the backlight power chip 260 is 20 mA
  • the backlight source 280 outputs the backlight to the outside according to the driving current of 0.352 mA.
  • the default desired brightness value 259 is manually modified to 50 by the user. Then, the backlight controller 220 queries the total table that the sub-table brightness value corresponding to the desired brightness value 50 is 100 in the first correspondence table, that is, the resistance branch corresponding to the desired brightness value 50 is the first resistance branch 272. . Since the second resistor branch 274 is connected to the set pin ISET at this time, the backlight controller 220 needs to switch the second resistor branch 274 connected to the set pin ISET to the first resistor branch 272. The backlight controller 220 first sends a switching signal to the control terminal C1 of the adjustable resistor circuit 270. The adjustable resistor circuit 270 connects the set pin ISET to the first resistor branch 272 after receiving the switching signal.
  • the backlight controller 220 further queries the first correspondence table to find that the duty ratio corresponding to the sub-table brightness value 100 is 20%, and the backlight controller 220 sends the duty ratio to the input pin IN of the backlight power chip 260 by 20%. PWM signal.
  • the reference current in the backlight power chip 260 is 0.2 mA
  • the backlight source 280 outputs the backlight to the outside according to the driving current of 0.04 mA.
  • the backlight controller 220 queries the total table that the sub-table brightness value corresponding to the desired brightness value 260 is 8 in the second correspondence table, that is, the desired brightness.
  • the resistor branch corresponding to value 260 is the second resistor branch 274. Since the first resistor branch 272 is connected to the set pin ISET at this time, the backlight controller 220 needs to switch the first resistor branch 272 connected to the set pin ISET to the second resistor branch 274.
  • the backlight controller 220 first sends a switching signal to the control terminal C1 of the adjustable resistor circuit 270.
  • the adjustable resistor circuit 270 connects the second resistor branch 274 to the setting pin ISET after receiving the switching signal.
  • the backlight controller 220 further queries the second correspondence table to find that the duty ratio corresponding to the sub-table brightness value 8 is 2.52%, and the backlight controller 220 sends the duty ratio to the input pin IN of the backlight power chip 260 to be 2.52%. PWM signal.
  • the reference current in the backlight power chip 260 is 20 mA
  • the backlight source 280 outputs the backlight to the outside according to the driving current of 0.504 mA.
  • the backlight controller 220 queries the total table that the sub-table brightness value corresponding to the desired brightness value 50 is 100 in the first correspondence table, and expects The sub-table brightness value corresponding to the brightness value 260 is 8 in the second correspondence table.
  • the backlight controller 220 gradually increases the duty ratio of the PWM signal currently output before the switching to a maximum duty ratio of 1 100% before transmitting the switching signal, as follows:
  • the backlight controller 220 first adds the sub-table brightness value from 100 in the first correspondence table to obtain the sub-table brightness value 101, and queries the first correspondence table to find that the duty ratio corresponding to the sub-table brightness value 101 is 20.19%. , sending a PWM signal with a duty ratio of 20.19% to the input pin IN, and the driving current is 0.04038 mA;
  • the backlight controller 220 further increases the sub-table brightness value from 101 in the first correspondence table to obtain the sub-table brightness value 102, and queries the first correspondence table to find that the duty ratio corresponding to the sub-table brightness value 102 is 20.38%. Sending a PWM signal with an output duty ratio of 20.38% to the input pin IN, and the driving current is 0.04076 mA;
  • the backlight controller 220 further increases the sub-table brightness value from 102 in the first correspondence table to obtain a sub-table bright.
  • the value 103 is obtained from the first correspondence table, and the duty ratio corresponding to the sub-table brightness value 103 is 20.57%, and the PWM signal with an output duty ratio of 20.57% is sent to the input pin IN, and the driving current is 0.04114. mA;
  • the backlight controller 220 sequentially increases the sub-table brightness value to the maximum value 511 in the first correspondence table, and outputs a PWM signal with a duty ratio of 100%, and the driving current is 0.2 mA, as shown in FIG. Show.
  • the backlight controller 220 After transmitting the switching signal, the backlight controller 220 also needs to gradually increase the PWM signal outputted after the switching from the minimum duty ratio 2 to the duty ratio 2.52% corresponding to the desired brightness value 260. details as follows:
  • the backlight controller 220 After the brightness value of the sub-table increases to the maximum value 511 in the first correspondence table, the backlight controller 220 sends a switching signal to the control terminal C1 of the adjustable resistance circuit 270, and the adjustable resistance circuit 270 will receive the switching signal after receiving the switching signal.
  • the two resistor branch 274 is connected to the set pin ISET.
  • the backlight controller 220 After switching from the first resistance branch 272 to the second resistance branch 274, the backlight controller 220 updates the sub-table brightness value to the minimum sub-table brightness value 0 in the second correspondence table, and queries the second correspondence table.
  • the backlight controller 220 obtains the sub-table brightness value 1 by adding 1 to the sub-table brightness value from the second correspondence table, and the duty ratio corresponding to the sub-table brightness value 1 is 1.19% from the second correspondence table. Sending a PWM signal with an output duty ratio of 1.19% to the input pin IN, and the driving current is 0.238 mA;
  • the backlight controller 220 sequentially increments the sub-table brightness value to the sub-table brightness value 8 in the second correspondence table, and sends a PWM signal with a duty ratio of 2.52% to the input pin IN, at which time the driving current is 0.504 mA.
  • the drive current is gradually increased from 0.04 mA, 0.04038 mA, 0.04076 mA, . . . , 0.2 mA, 0.238 mA, . . . , to 0.504 mA.
  • the backlight is gradually brighter. Not only is there no flicker, but the physical life of the backlight source 280 can be protected.
  • the user is sensitive to backlight changes in a dark environment, but since the adjustment step between adjacent two drive currents in the first correspondence table is 0.00038 mA, the adjacent two drive currents in the second correspondence table
  • the adjustment step between the steps is 0.038 mA, so the adjustment step size at the lower backlight brightness of the embodiment of the present invention is smaller than the adjustment step length at the higher backlight brightness, and the user does not easily perceive the adjacent two drive currents.
  • the above backlight adjustment process may be adjusted from a smaller desired brightness value to a larger desired brightness value, or may be adjusted from a larger desired brightness value to a smaller desired brightness value.
  • the electronic device connects the set pin of the backlight power chip to the adjustable resistor circuit, and the adjustable resistor circuit connects the resistor branch connected to the set pin according to the switching signal.
  • a resistor branch is switched to the second resistor branch, thereby changing the reference current in the backlight power chip, thereby changing the current value adjustment range of the driving current; and solving the hardware performance limited by the backlight power chip, the backlight power chip can only be in
  • the output current is limited within the limited current value adjustment range, and the brightness of the backlight LED output is also in the finite brightness range; the reference current in the backlight power supply is changed by different resistance branches, thereby achieving output in more current value adjustment range.
  • the driving current is such that the backlight intensity reaches a lower brightness or higher brightness effect.
  • the current value adjustment range corresponding to the branch circuit and the current value adjustment range corresponding to the second resistance branch can be combined into one continuous current value adjustment range, thereby realizing a current range adjustment range with a large variation range.
  • the current value adjustment range in which the variation range is large is such that there is no flicker when switching between the first resistance branch and the second resistance branch.
  • the electronic device provided by the embodiment of the present invention further increases the brightness value of the first sub-table by gradually increasing or decreasing by 1 after the desired brightness value is changed from the first sub-table brightness value to the second sub-table brightness value.
  • the driving current is gradually changed, and the backlight is also gradually changed, so that the user's eyes can better adapt to the backlight changing process and protect the physical life of the backlight source.
  • the electronic device provided by the embodiment of the invention further reduces the adjustment step between two adjacent driving currents in a lower current value adjustment range, so that the user is sensitive to backlight changes in a dark environment. It is also not easy to perceive the change between two adjacent drive currents. That is, the backlight grading process at a lower backlight brightness is more delicate and soft.
  • the backlight controller 220 has the ability to adjust the backlight brightness at 1024 brightness levels.
  • three tables need to be stored in the memory 240: a summary table, a first correspondence table, and a second correspondence table.
  • the summary table, the first correspondence table, and the second correspondence table can be integrated into one table. If the backlight register is still 9 bits, the table is as shown in Table 5:
  • the adjustment step between adjacent two duty ratios is changed from 0.19% to 0.38, and the backlight controller 220 can adjust the backlight luminance only at 512 brightness levels.
  • the resistance branch corresponding to the desired luminance value [0, 255] is the first resistance branch
  • the resistance branch corresponding to the desired luminance value [256, 511] is the second resistance branch.
  • the two current value adjustment ranges do not intersect each other.
  • the current value adjustment range corresponding to the first resistance circuit 272 is [0.0015 mA, 0.15 mA]
  • the current value adjustment range corresponding to the second resistance branch 274 is [0.16 mA, 16 mA].
  • the range between the two current value adjustment ranges is small, for example, only 0.1 mA between 0.15 mA and 0.16 mA, the drive current jump when the two resistance branches are switched is weak, and the user is difficult to observe. To the jump.
  • the two current value adjustment ranges intersect at the boundary value.
  • the current value adjustment range corresponding to the first resistance circuit 272 is [0.0015 mA, 0.15 mA]
  • the current value adjustment range corresponding to the second resistance branch 274 is [0.15 mA, 15 mA].
  • the two current value adjustment ranges can be connected to form a continuous current value adjustment range.
  • the two current value adjustment ranges intersect in a section.
  • the current value adjustment range corresponding to the first resistance circuit is [0.0015 mA, 0.15 mA]
  • the current value adjustment range corresponding to the second resistance branch is [0.10 mA, 10 mA].
  • the minimum duty cycle and/or maximum duty cycle of the range can be such that the two current value adjustment ranges do not intersect each other or only intersect at the boundary value.
  • the current value adjustment range corresponding to the second resistor branch becomes [0.15 mA, 10 mA].
  • FIG. 6 is a flowchart of a method for adjusting a backlight according to an embodiment of the present invention.
  • the method can be performed by the backlight controller 220 provided in the embodiment shown in FIG. 2 above.
  • the method includes:
  • Step 601 Obtain a desired brightness value, where the desired brightness value is used to indicate a brightness of a backlight that is desired to be emitted by the backlight source;
  • the desired brightness value is the default desired brightness value
  • the change of the desired brightness value includes but is not limited to the following three modes:
  • the user manually sets the desired brightness value to be changed
  • the application changes the desired brightness value according to its own control logic
  • the operating system changes the desired brightness value based on the ambient light intensity.
  • Step 602 determining a resistance branch corresponding to the desired brightness value, the resistance branch being one of the first resistance branch and the second resistance branch;
  • the backlight controller determines the resistance branch corresponding to the desired brightness value by looking up the summary table shown in Table 2 or the correspondence table shown in Table 5.
  • Step 603 when the resistance branch corresponding to the desired brightness value and the resistance branch connected to the set pin are different, send a switching signal to the control end of the adjustable resistance circuit;
  • Step 604 sending a PWM signal to the backlight power chip, the duty ratio of the PWM signal corresponding to the desired brightness value;
  • the backlight controller determines the duty ratio corresponding to the desired brightness value by querying the first correspondence table shown in Table 3, or querying the second correspondence table shown in Table 4, or the correspondence table shown in Table 5. Then, the backlight controller sends a PWM signal conforming to the duty ratio to the input pin IN of the backlight power chip.
  • the backlight power chip is configured to generate a driving current according to a duty ratio of the PWM signal based on a reference current, and send a driving current to the backlight source, and the backlight source is configured to emit a backlight according to the driving current.
  • the backlight adjustment method obtains a desired brightness value by the backlight controller, and is adjustable when the resistance branch corresponding to the desired brightness value and the resistance branch connected to the set pin are different.
  • the control end of the resistance circuit sends a switching signal, and the adjustable resistance circuit switches the resistance branch connected to the set pin between the first resistance branch and the second resistance branch according to the switching signal, thereby changing the back
  • the reference current in the optical power chip because the driving current is generated based on the reference current, further changes the current value adjustment range of the driving current; and solves the limitation of the hardware performance of the backlight power chip, the backlight power chip can only be limited
  • the output driving current in the current value adjustment range causes the brightness of the backlight source output to belong to the finite brightness range; the reference current in the backlight power supply is changed through different resistance branches, thereby achieving output in a larger current value adjustment range.
  • the driving current is such that the backlight intensity reaches a lower brightness or higher brightness effect.
  • the backlight controller can also gradually adjust the driving current during the backlight switching process.
  • R1>R2 is adjusted from a smaller desired brightness value corresponding to the first resistance branch to a larger desired brightness value corresponding to the second resistance branch;
  • R1 ⁇ R2 is adjusted from a larger desired brightness value corresponding to the first resistance branch to a smaller desired brightness value corresponding to the second resistance branch;
  • R1>R2 is adjusted from a larger desired brightness value corresponding to the second resistance branch to a smaller desired brightness value corresponding to the first resistance branch;
  • R1 ⁇ R2 is adjusted from a smaller desired luminance value corresponding to the second resistive branch to a larger desired luminance value corresponding to the first resistive branch.
  • FIG. 7A shows a flowchart of a backlight adjustment method according to another embodiment of the present invention.
  • the method can be performed by the backlight controller 220 provided in the embodiment shown in Fig. 2 above for implementing the backlight adjustment of the first embodiment described above.
  • the method includes:
  • Step 701 Obtain a desired brightness value, where the desired brightness value is used to indicate a brightness of a backlight that is desired to be emitted by the backlight source;
  • the desired brightness value is the default desired brightness value
  • the change of the desired brightness value includes but is not limited to the following three modes:
  • the user manually sets the desired brightness value to be changed
  • the application changes the desired brightness value according to its own control logic
  • the operating system changes the desired brightness value based on the ambient light intensity.
  • Step 702 determining a resistance branch corresponding to the desired brightness value, the resistance branch being one of the first resistance branch and the second resistance branch;
  • the backlight controller determines the resistance branch corresponding to the desired brightness value by looking up the summary table shown in Table 2 or the correspondence table shown in Table 5.
  • Step 703 when the resistance branch corresponding to the desired brightness value is different from the resistance branch connected to the set pin, the resistance branch connected to the set pin is the first resistance branch and the resistance of the first resistance branch is greater than When the resistance of the second resistance branch is increased, the duty ratio of the currently output PWM signal is gradually increased to the maximum duty ratio 1 ;
  • the maximum duty cycle 1 is the maximum duty cycle when the set pin is connected to the first resistor branch.
  • the backlight controller limits the adjustment step used when the duty ratio of the currently output PWM signal is gradually increased to the maximum duty ratio 1 .
  • the adjustment step size may be a difference between duty ratios corresponding to luminance values of two adjacent sub-tables, such as 0.19% shown in Table 3 or Table 4; or may be corresponding to two adjacent desired luminance values.
  • the difference in the air ratio such as 0.38% shown in Table 5, or other possible values.
  • Step 704 sending a switching signal to the control end of the adjustable resistance circuit
  • the switching signal is used to trigger the adjustable resistance circuit to connect the second resistance branch to the set pin;
  • the switching signal is used to trigger the adjustable resistor circuit to connect the first resistor branch to the set pin.
  • Step 705 query a duty ratio corresponding to a desired brightness value
  • the backlight controller queries the total table, the first correspondence table, and the second correspondence table for the duty ratio corresponding to the desired brightness value; or the backlight controller queries the correspondence table shown in Table 5 to query the corresponding brightness value. Duty cycle.
  • Step 706 after the switch is connected to the set pin, the resistor branch is the second resistor branch and the resistance of the first resistor branch is greater than the resistance of the second resistor branch, and the current output PWM signal is minimized.
  • the null ratio 2 is gradually increased to a duty ratio corresponding to the desired luminance value;
  • the minimum duty cycle 2 is the minimum duty cycle when the set pin is connected to the second resistor branch.
  • the backlight controller is not limited to the adjustment step size used when the currently output PWM signal minimum duty ratio 2 is gradually increased to the duty ratio corresponding to the desired luminance value.
  • the adjustment step size may be a difference between duty ratios corresponding to luminance values of two adjacent sub-tables, such as 0.19% shown in Table 3 or Table 4; or may be corresponding to two adjacent desired luminance values.
  • the difference in the air ratio such as 0.38% shown in Table 5, or other possible values.
  • the backlight adjustment method provided in this embodiment can make the PWM signal gradually change before the switching signal is sent through step 703, and does not cause a sudden change in the backlight brightness, thereby avoiding the flicker phenomenon of the backlight brightness.
  • the PWM signal can be gradually changed after the switching signal is transmitted, and the sudden change of the backlight brightness is not caused, and the flicker phenomenon of the backlight brightness is avoided.
  • step 703 can be implemented as step 703a instead, and the above step 706 can be alternatively implemented as step 706a, as shown in FIG. 7B:
  • Step 703a when the resistance branch corresponding to the desired brightness value is different from the resistance branch connected to the set pin, the resistance branch connected to the set pin is the first resistance branch and the resistance of the first resistance branch is less than When the resistance of the second resistor branch is reduced, the duty ratio of the currently output PWM signal is gradually reduced to a minimum duty ratio of 1 .
  • the minimum duty cycle 1 is the maximum duty cycle when the set pin is connected to the first resistor branch.
  • Step 706a after the switch is connected to the set pin, the resistance branch is the second resistor branch and the resistance of the first resistor branch is smaller than the resistance of the second resistor branch, and the current output PWM signal is maximized.
  • the null ratio 2 is gradually reduced to a duty ratio corresponding to the desired luminance value.
  • the maximum duty cycle 2 is the maximum duty cycle when the set pin is connected to the second resistor branch.
  • step 703 can be implemented as step 703b instead, and the above step 706 can be alternatively implemented as step 706b, as shown in FIG. 7c:
  • Step 703b when the resistance branch corresponding to the desired brightness value and the resistance branch connected to the set pin are different, the resistance branch connected to the set pin is the second resistance branch and the resistance of the first resistance branch is greater than When the resistance of the second resistor branch is reduced, the duty ratio of the currently output PWM signal is gradually reduced to a minimum duty ratio of 2 .
  • the minimum duty cycle 2 is the minimum duty cycle when the set pin is connected to the second resistor branch.
  • Step 706b after the switch is connected to the set pin, the resistor branch is the first resistor branch and the resistance of the first resistor branch is greater than the resistance of the second resistor branch, and the current output PWM signal is maximized.
  • the null ratio 1 is gradually reduced to a duty ratio corresponding to the desired luminance value.
  • the maximum duty cycle 1 is the maximum duty cycle when the set pin is connected to the second resistor branch.
  • step 703 can be implemented as step 703c instead, and the above step 706 can be replaced as step 706c, as shown in FIG. 7C:
  • Step 703c when the resistance branch corresponding to the desired brightness value is different from the resistance branch connected to the set pin, the resistance branch connected to the set pin is the second resistance branch and the resistance of the first resistance branch is less than When the resistance of the second resistance branch is increased, the duty ratio of the currently output PWM signal is gradually increased to the maximum duty ratio 2 .
  • the maximum duty cycle 2 is the maximum duty cycle when the set pin is connected to the second resistor branch.
  • Step 706c after the switch is connected to the set pin, the resistance branch is the first resistor branch and the resistance of the first resistor branch is smaller than the resistance of the second resistor branch, and the minimum output of the currently output PWM signal is The null ratio 1 is gradually increased to a duty ratio corresponding to the desired luminance value.
  • the minimum duty cycle 1 is the minimum duty cycle when the set pin is connected to the second resistor branch.
  • a person skilled in the art may understand that all or part of the steps of implementing the above embodiments may be completed by hardware, or may be instructed by a program to execute related hardware, and the program may be stored in a computer readable storage medium.
  • the storage medium mentioned may be a read only memory, a magnetic disk or an optical disk or the like.

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Abstract

一种背光电路、电子设备及背光调节方法，涉及液晶显示领域，所述背光电路包括：背光电源芯片（260）和可调电阻电路（270）；背光电源芯片（260）包括用于设置参考电流的设置引脚（ISET）、输入引脚（IN）和输出引脚（OUT）；可调电阻电路（270）的一端与所述设置引脚（ISET）相连；可调电阻电路（270）还包括：控制端（C1），控制端（C1）用于接收切换信号，根据切换信号将与设置引脚（ISET）相连的电阻支路从第一电阻支路（272）切换为第二电阻支路（274）；背光电源芯片（260），用于以参考电流为基准，根据输入引脚（IN）接收到的PWM信号的占空比生成驱动电流；通过输出引脚（OUT）输出驱动电流。通过不同电阻支路改变背光电源中的参考电流，从而实现在更大的电流值调节范围内输出驱动电流，使得背光强度达到更低亮度或更高亮度。

Description

背光电路、电子设备及背光调节方法 技术领域
本发明实施例涉及液晶显示领域，特别涉及一种背光电路、电子设备及背光调节方法。
背景技术
诸如智能手机、平板电脑之类的电子设备，均采用液晶显示屏(英文：Liquid Crystal Display，简称：LCD)作为显示组件。
LCD需要使用背光电路提供背光才能正常显示。背光电路被背光控制器所控制。背光电路包括：背光电源芯片和与背光电源芯片相连的背光发光二极管(英文：Light Emitting Diode，简称：LED)。在工作过程中，背光电源芯片接收背光控制器发送的脉宽调制(英文：Pulse-Width Modulation，简称：PWM)信号，背光电源芯片根据脉宽调制信号向背光LED输出驱动电流，背光LED根据驱动电流发出背光。其中，驱动电流的大小与背光强度呈正相关关系，也即驱动电流越大，背光强度越高；驱动电流越小，背光强度越低。
受限于背光电源芯片的硬件性能，背光电源芯片输出的驱动电流的电流大小属于有限范围，导致背光LED输出的背光亮度也属于有限亮度范围。换句话说，背光LED输出的最低亮度或最高亮度并不是开发人员在设计时所期望的理想亮度或背光LED实际所能输出的极限亮度。
发明内容
为了解决受限于背光电源芯片的硬件性能，背光电源芯片只能在有限的电流值调节范围内输出驱动电流，导致背光LED输出的亮度也属于有限亮度范围的问题，本发明实施例提供了一种背光电路、电子设备及背光调节方法。所述技术方案如下：
第一方面，本发明实施例提供了一种背光电路，所述背光电路包括：背光电源芯片和可调电阻电路；所述背光电源芯片包括：用于设置参考电流的设置引脚、输入引脚和输出引脚；所述可调电阻电路的一端与所述设置引脚相连， 所述可调电阻电路的另一端接地，所述可调电阻电路包括第一电阻支路和第二电阻支路，所述第一电阻支路和所述第二电阻支路具有不同的电阻值，用于产生不同的所述参考电流；所述可调电阻电路包括：控制端，所述控制端用于接收切换信号，根据所述切换信号将与所述设置引脚相连的电阻支路在所述第一电阻支路和所述第二电阻支路之间切换；所述背光电源芯片，用于以所述参考电流为基准，根据所述输入引脚接收到的PWM信号的占空比生成驱动电流；通过所述输出引脚输出所述驱动电流，所述驱动电流用于驱动背光光源发送背光。
第一方面所提供的背光电路，通过将背光电源芯片的设置引脚与可调电阻电路相连，由可调电阻电路根据切换信号将与设置引脚相连的电阻支路在第一电阻支路和第二电阻支路之间切换，从而改变背光电源芯片中的参考电流，由于驱动电流是基于参考电流产生的，所以进而会改变驱动电流的电流值调节范围；解决了受限于背光电源芯片的硬件性能，背光电源芯片只能在有限的电流值调节范围内输出驱动电流，导致背光光源输出的亮度也属于有限亮度范围的问题；达到了通过不同电阻支路改变背光电源中的参考电流，从而实现在更大的电流值调节范围内输出驱动电流，使得背光强度达到更低亮度或更高亮度的效果。
在第一方面的第一种可能的实施方式中，所述可调电阻电路包括：选择开关和至少两条电阻支路；所述至少两条电阻支路中的任意一条电阻支路为所述第一电阻支路，所述至少两条电阻支路中的另一条电阻支路为所述第二电阻支路；所述选择开关包括：所述控制端和选择端；所述选择端，用于根据所述控制端接收到的所述切换信号，将与所述设置引脚相连的电阻支路在所述第一电阻支路和所述第二电阻支路之间进行切换。在本实施方式中，通过在可调电阻电路中设置选择开关和至少两条电阻支路，能够在可调电阻电路中实现三支电阻支路，四支电阻支路甚至更多，从而针对驱动电流实现更大的电流值调节范围。
结合第一方面的第一种可能的实施方式，在第二种可能的实施方式中，所述可调电阻电路包括串联的第一电阻和第二电阻；所述第一电阻和所述第二电阻形成所述第一电阻支路；所述第二电阻形成所述第二电阻支路；或，所述第一电阻和所述第二电阻形成所述第二电阻支路；所述第二电阻形成所述第一电阻支路。在本实施方式中，通过串联电路实现可调电阻电路中的电阻支路，电 路形式简易，容易在电路板上设计和生产。
结合第一方面的第一种可能的实施方式，在第三种可能的实施方式中，所述可调电阻电路包括并联的第三电阻和第四电阻；所述第三电阻形成所述第一电阻支路；所述第四电阻形成所述第二电阻支路。在本实施方式中，通过并联电路实现可调电阻电路中的电阻支路，电路形式简易，容易在电路板上设计和生产。
结合第一方面或第一方面的第一种可能的实施方式或第一方面的第二种可能的实施方式或第一方面的第三种可能的实施方式，在第五种可能的实施方式中，所述切换信号是背光控制器在与期望亮度值对应的电阻支路和与所述设置引脚相连的电阻支路不同时发送的；所述期望亮度值用于表示期望所述背光光源发出的背光亮度。
第二方面，本发明实施例提供了一种电子设备，所述电子设备包括：背光控制器、存储器、如第一方面或第一方面的任意一种可能的实施方式所提供的背光电路、以及背光光源；所述存储器与所述背光控制器相连，所述存储器存储有所述背光控制器的可执行程序；
所述背光控制器与所述背光电路中的所述输入引脚相连，用于向所述背光电源芯片发送所述PWM信号；所述背光控制器与所述背光电路中的所述控制端相连，用于向所述可调电阻电路发送所述切换信号；
所述背光电路中的所述背光电源芯片的所述输出引脚与所述背光光源相连；所述背光光源用于根据所述驱动电流发出背光。
在第二方面的第一种可能的实施方式中，所述背光控制器是：中央处理器(英文：Central Processing Unit；简称：CPU)；或者，背光控制器220是图形处理器(英文：Graphics Processing Unit，简称：GPU)；或者，背光控制器220是LCD驱动集成电路(英文:Driver integrated circuit，简称：Drive IC)。
在第二方面的第二种可能的实施方式中，背光控制器被配置为执行存储器中的指令，所述背光控制器通过执行指令来实现下述第三方面或第三方面的任意一种可能的实现方式所提供的背光调节方法。
第三方面，本发明实施例提供了一种背光调节方法，应用于如第二方面所提供的电子设备的背光控制器中，所述方法包括：背光控制器获取期望亮度值，所述期望亮度值用于表示期望所述背光光源发出的背光亮度；所述背光控制器确定与所述期望亮度值对应的电阻支路，所述电阻支路是所述第一电阻支路和 所述第二电阻支路中的一个；当与所述期望亮度值对应的电阻支路和与所述设置引脚相连的电阻支路不同时，所述背光控制器向所述可调电阻电路的控制端发送切换信号；所述背光控制器向所述背光电源芯片发送PWM信号，该PWM信号的占空比与所述期望亮度值对应；所述背光电源芯片用于以所述参考电流为基准，根据所述PWM信号的占空比生成驱动电流，向所述背光光源发送所述驱动电流，所述背光光源用于根据所述驱动电流发出背光。
第三方面所提供的背光调节方法，通过由背光控制器获取期望亮度值，在与期望亮度值对应的电阻支路和与设置引脚相连的电阻支路不同时，向可调电阻电路的控制端发送切换信号，由可调电阻电路根据切换信号将与设置引脚相连的电阻支路在第一电阻支路和第二电阻支路之间切换，从而改变背光电源芯片中的参考电流，由于驱动电流是基于参考电流产生的，所以进而会改变驱动电流的电流值调节范围；解决了受限于背光电源芯片的硬件性能，背光电源芯片只能在有限的电流值调节范围内输出驱动电流，导致背光光源输出的亮度也属于有限亮度范围的问题；达到了通过不同电阻支路改变背光电源中的参考电流，从而实现在更大的电流值调节范围内输出驱动电流，使得背光强度达到更低亮度或更高亮度的效果。
在第三方面的第一种可能的实施方式中，在向所述可调电阻电路的控制端发送切换信号之前，还包括：若与所述设置引脚相连的电阻支路是所述第一电阻支路且所述第一电阻支路的阻值大于所述第二电阻支路的阻值时，将当前输出的PWM信号的占空比逐渐增加至最大占空比1，所述最大占空比1是所述设置引脚与所述第一电阻支路相连时的最大占空比；若与所述设置引脚相连的电阻支路是所述第一电阻支路且所述第一电阻支路的阻值小于所述第二电阻支路的阻值时，将当前输出的PWM信号的占空比逐渐减小至最小占空比1，所述最小占空比1是所述设置引脚与所述第一电阻支路相连时的最小占空比；若与所述设置引脚相连的电阻支路是所述第二电阻支路且所述第一电阻支路的阻值大于所述第二电阻支路的阻值时，将当前输出的PWM信号的占空比逐渐减小至最小占空比2，所述最小占空比2是所述设置引脚与所述第二电阻支路相连时的最小占空比；若与所述设置引脚相连的电阻支路是所述第二电阻支路且所述第一电阻支路的阻值小于所述第二电阻支路的阻值时，将当前输出的PWM信号的占空比逐渐增大至最大占空比2，所述最大占空比2是所述设置引脚与所述第二电阻支路相连时的最大占空比。在本实施方式中，能够使得PWM 信号在发送切换信号之前是逐渐变化的，不会引发背光亮度的突变，避免背光亮度的闪烁现象。
在第三方面的第二种可能的实施方式中，所述向所述背光电源芯片发送PWM信号，该PWM信号的占空比与所述期望亮度值对应，包括：查询与所述期望亮度值对应的所述占空比；在切换后与所述设置引脚相连的电阻支路是所述第二电阻支路且所述第一电阻支路的阻值大于所述第二电阻支路的阻值时，将当前输出的所述PWM信号从最小占空比2逐渐增加至所述占空比，所述最小占空比2是所述设置引脚与所述第二电阻支路相连时的最小占空比；在切换后与所述设置引脚相连的电阻支路是所述第二电阻支路且所述第一电阻支路的阻值小于所述第二电阻支路的阻值时，将当前输出的所述PWM信号从最大占空比2逐渐减小至所述占空比，所述最大占空比2是所述设置引脚与所述第二电阻支路相连时的最大占空比；在切换后与所述设置引脚相连的电阻支路是所述第一电阻支路且所述第一电阻支路的阻值大于所述第二电阻支路的阻值时，将当前输出的所述PWM信号从最大占空比1逐渐减小至所述占空比，所述最大占空比1是所述设置引脚与所述第一电阻支路相连时的最大占空比；在切换后与所述设置引脚相连的电阻支路是所述第一电阻支路且所述第一电阻支路的阻值小于所述第二电阻支路的阻值时，将当前输出的所述PWM信号的最小占空比1逐渐增大至所述占空比，所述最小占空比1是所述设置引脚与所述第一电阻支路相连时的最小占空比。在本实施方式中，能够使得PWM信号在发送切换信号之后是逐渐变化的，不会引发背光亮度的突变，避免背光亮度的闪烁现象。
结合上述各个方面或各个方面的各种可能的实施方式，在可能的实施方式中，所述第一电阻支路的阻值R1和所述第二电阻支路的阻值R2满足如下条件：
R1≥R2*最大占空比2/最小占空比1；
或者，R1≤R2*最小占空比1/最大占空比2；
其中，所述最小占空比1是所述设置引脚与所述第一电阻支路相连时的最小占空比；所述最大占空比1是所述设置引脚与所述第一电阻支路相连时的最大占空比；所述最小占空比2是所述设置引脚与所述第二电阻支路相连时的最小占空比；所述最大占空比2是所述设置引脚与所述第二电阻支路相连时的最大占空比。在本实施方式中，通过令R1＝R2*最大占空比2/最小占空比1，或者， R1＝R2*最小占空比1/最大占空比2，能够使得第一电阻支路对应的电流值调节范围和第二电阻支路对应的电流值调节范围能够合并为一个连续的电流值调节范围，从而实现一个变化范围较大的电流值调节范围。该变化范围较大的电流值调节范围使得将第一电阻支路和第二电阻支路之间进行切换时，没有闪烁现象。
附图说明
为了更清楚地说明本发明实施例中的技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是一种已有的电子设备的结构示意图；
图2是本发明一个实施例提供的电子设备的结构示意图；
图3A是本发明一个实施例提供的可调电阻电路的结构示意图；
图3B是本发明另一个实施例提供的可调电阻电路的结构示意图；
图3C是本发明另一个实施例提供的可调电阻电路的结构示意图；
图4是本发明一个实施例提供的电子设备的结构示意图；
图5是图4所示电子设备在进行背光调节时的原理示意图；
图6是本发明一个实施例提供的背光调节方法的流程图；
图7A是本发明一个实施例提供的背光调节方法的流程图；
图7B是本发明一个实施例提供的背光调节方法的流程图；
图7C是本发明一个实施例提供的背光调节方法的流程图；
图7D是本发明一个实施例提供的背光调节方法的流程图。
具体实施方式
为使本发明的目的、技术方案和优点更加清楚，下面将结合附图对本发明实施方式作进一步地详细描述。
请参考图1，其示出了一种已有的电子设备100的结构示意图。该电子设备100包括：背光控制器120、存储器140、背光电源芯片160和背光光源180。
背光控制器120可以是中央处理器(英文：Central Processing Unit；简称： CPU)；或者，背光控制器120也可以是图形处理器(英文：Graphics Processing Unit，简称：GPU)；或者，背光控制器120还可以是LCD驱动集成电路(英文:Driver integrated circuit，简称：Drive IC)。
存储器140中存储有背光控制器120的可执行指令。存储器140可以由任何类型的易失性或非易失性存储设备或者它们的组合实现，如静态随机存取存储器(英文：Static Random Access Memory，简称：SRAM)，电可擦除可编程只读存储器(英文：Electrically Erasable Programmable Read-Only Memory，简称：EEPROM)，可擦除可编程只读存储器(英文：Erasable Programmable Read Only Memory，简称：EPROM)，可编程只读存储器(英文：Programmable Read-Only Memory，简称：PROM)，只读存储器(英文：Read Only Memory，简称：ROM)，磁存储器，快闪存储器，磁盘或光盘。
背光电源芯片160是一种基于PWM信号输出驱动电流的集成电路芯片。背光电源芯片160包括有：输入引脚IN、设置引脚ISET、输出引脚OUT。背光电源芯片160的内部包括：参考电流源电路162。
输入引脚IN与背光控制器120相连。
设置引脚ISET与背光电源芯片160内部的参考电流源电路162相连，设置引脚ISET还与背光电源芯片160外部的电阻RISET的一端相连，电阻RISET的另一端接地。
参考电流源电路162用于提供一个参考电流IFB_full，该参考电流的计算公式为：
IFB_full＝VISET_full/RISET*KISET_full  公式一
其中，VISET_full是电压值固定不变的参考电压；KISET_full是固定参数，KISET_full由参考电流源电路162中电子元件的电气性能所决定。显然，由于VISET_full、RISET、KISET_full三个参数均为固定值，所以该参考电流源电路162所提供的参考电流的电流值也是固定值。
此外，背光电源芯片160的一个引脚与电源VBAT相连，另一个引脚接地。
背光光源180通常是背光LED。背光光源180的一端与电源VBAT相连，另一端与背光电源芯片160中的输入引脚OUT相连。
在工作时，背光控制器140根据预定的背光控制策略生成期望亮度值。该期望亮度值是背光控制器120期望背光光源180所发出的背光亮度。比如，该预定的背光控制策略是：在环境光亮度变暗时，调低期望亮度值；在环境光亮 度变亮时，调高期望亮度值。
该期望亮度值通常采用9比特或者11比特的二进制数来表示，并且存储在一个背光寄存器Reg_Iset中。本实施例中以9比特表示为例，期望亮度值是000000000，也即十进制的0；或者，期望亮度值是111111111，也即十进制的511。需要说明的是，期望亮度值仅为亮度级别或亮度档位的示意方式，与实际物理量中的亮度值并不等同。
然后，背光控制器140在预先存储的“期望亮度值-占空比”对应表中，查询与期望亮度值对应的占空比。该“期望亮度值-占空比”对应表存储在存储器140中。表一示例性地示出了“期望亮度值-占空比”对应表。为了便于阅读和理解，下文中均以十进制来表示期望亮度值。
表一
Figure PCTCN2015096869-appb-000001
显然，由于期望亮度值的取值范围为[0，511]，而占空比的取值范围为[1％，100％]，所以相邻两个期望亮度值之间的占空比调节步长约为0.19％。背光控制器140向背光电源芯片160的输入引脚发送符合该占空比的PWM信号。比如，期望亮度值为4，则背光控制器140向背光电源芯片160的输入引脚发送占空比为1.76％的PWM信号。
背光电源芯片160在接收到该PWM信号后，以参考电流为基准，根据PWM信号的占空比生成驱动电流。该驱动电流的电流大小与PWM信号的占空比呈正比例关系。驱动电流的电流值计算公式如下：
IFBX＝IFB_full*Duty。  公式2
其中，IFB_full是参考电流，Duty是占空比。
比如，PWM信号的占空比为1％，参考电流是20mA，则驱动电流＝20mA*1％＝0.2mA；又比如，PWM信号的占空比为100％，参考电流是20mA，则驱动电流＝20mA*100％＝20mA。
受限于背光电源芯片160的物理性能，背光电源芯片160所能接收的最小占空比约为1％，所以背光电源芯片160所能输出的最小驱动电流约等于：1％*参考电流，最大驱动电流约等于：100％*参考电流，也即驱动电流的电流值调节范围为[1％*IFB_ful,100％*IFB_ful]，结合表一的示意性举例，该电流值调节范围为[2mA,20mA]。显然，该电流值调节范围比较有限。
由于驱动电流的电流值调节范围比较有限，在某些暗光条件下，即便采用最小驱动电流来驱动背光光源180，背光电源180所发出的背光仍然会非常强烈，从而刺激用户的眼睛。同理，在某些亮光条件下，即便采用最大驱动电流来驱动背光光源180，背光电源180所发出的背光仍然比较弱，无法看清液晶显示屏上的显示内容。
另外，该电流值调节范围内的最大调节步数是512步，相邻两个背光亮度值之间的驱动电流的电流值变化约为：0.19％*参考电流。
根据上述公式二可知，驱动电流的电流值与参考电流有关。为了获得电流值更小的驱动电流或者电流值更大的驱动电流，本发明实施例提供了一种基于改变参考电流，从而获得电流值取值范围更大的驱动电流的技术方案。另外，结合上述公式一可知，如果要改变参考电流，可以改变电阻RISET的阻值。基于上述思路，提供有如下实施例。
请参考图2，其示出了本发明一个实施例提供的电子设备200的结构示意图。背光控制器220、存储器240、背光电源芯片260、可调电阻电路270和背光光源280。
背光控制器220可以是中央处理器(英文：Central Processing Unit；简称：CPU)；或者，背光控制器220也可以是图形处理器(英文：Graphics Processing Unit，简称：GPU)；或者，背光控制器220也可以是LCD驱动集成电路(英文:Driver integrated circuit，简称：Drive IC)。
存储器240中存储有背光控制器220的可执行指令。存储器240可以由任何类型的易失性或非易失性存储设备或者它们的组合实现，如静态随机存取存储器(英文：Static Random Access Memory，简称：SRAM)，电可擦除可编程 只读存储器(英文：Electrically Erasable Programmable Read-Only Memory，简称：EEPROM)，可擦除可编程只读存储器(英文：Erasable Programmable Read Only Memory，简称：EPROM)，可编程只读存储器(英文：Programmable Read-Only Memory，简称：PROM)，只读存储器(英文：Read Only Memory，简称：ROM)，磁存储器，快闪存储器，磁盘或光盘。
背光电源芯片260，包括：输入引脚IN、用于设置参考电流的设置引脚ISET和输出引脚OUT。背光电源芯片260的内部还包括有：参考电流源电路262。
输入引脚IN与背光控制器220相连。在工作时，背光控制器220用于向输入引脚IN发送PWM信号。
可调电阻电路270的一端与设置引脚ISET相连，可调电阻电路270的另一端接地。可调电阻电路270包括第一电阻支路272和第二电阻支路274，第一电阻支路272的阻值不同于第二电阻支路274的阻值。需要说明的是，虽然图2示出了第一电阻支路272和第二电阻支路274，但这并不构成对其数量的限定。例如，图3A还示出了包括其他电阻支路的多个电阻支路。
可调电阻电路270包括：控制端C1。该控制端C1与背光控制器220相连。在需要改变驱动电流的调节范围时，背光控制器220用于向控制端C1发送切换信号。
控制端C1用于接收切换信号，根据切换信号将与设置引脚ISET相连的电阻支路从第一电阻支路272切换为第二电阻支路274。由于背光电源芯片260中包括有参考电流源电路262，该参考电流源电路用于提供参考电流262。在与设置引脚ISET相连的电阻支路的阻值发生改变时，背光电源芯片260中的参考电流的电流值也会发生改变。其中，参考电流的大小和与设置引脚ISET相连的电阻支路的阻值呈反比例关系。
背光电源芯片220中的输出引脚OUT与背光光源460的一端相连。背光电源460通常是背光LED。可选地，背光光源460的另一端与电源VBAT相连。
可选地，上述背光电源芯片260和可调电阻电路270可以集成在电子设备的主板上，该主板上通常还设置有背光控制器220、存储器240以及其它电子器件。背光电源芯片260为设置在主板上的一块集成电路芯片。背光电源芯片260通过主板上的导电线路与可调电阻电路270电性相连。
可选地，设置引脚ISET在不同的实施例中可能具有不同的名称，比如，满量程设置引脚，但均为用于设置参考电流的引脚。本实施例对设置引脚ISET 的名称不做具体限定。
结合参考图3A，其示例性地示出了一种可调电阻电路270的结构示意图。该可调电阻电路270包括：选择开关271、第一电阻支路272和第二电阻支路274。
选择开关271包括：控制端C1和选择端C2。
控制端C1用于与背光控制器220相连。
选择端C2，用于根据控制端C1接收到的切换信号，将设置引脚ISET与第一电阻支路272和第二电阻支路272中的一条电阻支路相连。
可选地，在亮光条件下，选择端C2根据控制端C1接收到的切换信号，将设置引脚ISET与阻值较小的电阻支路相连，使得背光电源芯片220中的参考电流的电流值为较大的电流值，从而在同等占空比条件下输出较大的驱动电流，得到更高的背光亮度；在暗光条件下，选择端C2根据控制端C1接收到的切换信号，将设置引脚ISET与阻值较大的电阻支路相连，使得背光电源芯片270中的参考电流的电流值为较小的电流值，从而在同等占空比条件下输出较小的驱动电流，得到更低的背光亮度。
可选地，控制端C1是符合通用标准输入输出(英文：General Purpose Input Output，简称：GPIO)的控制端C1。
可选地，可调电阻电路270中的电阻支路为两条。但也可以视实施例需求而设置三条、四条甚至更多，本实施例对可调电阻电路270中的电阻支路的条数不做限定。
可选地，可调电阻电路270通过集成化的可变电阻器件实现。
可选地，可调电阻电路270中的电阻支路通过串联电路或并联电路实现。
示意性地，结合参考图3B，其示出了使用串联电路实现可调电阻电路270的结构示意图。可调电阻电路270包括：选择开关271、串联的第一电阻RISET1和第二电阻RISET2；
第一电阻RISET1和第二电阻RISET2形成第二电阻支路274；第二电阻RISET2形成第一电阻支路272。
其中，第二电阻RISET2的一端与设置引脚ISET相连，第二电阻RISET2的另一端与第一电阻RISET1的一端相连，第一电阻RISET1的另一端接地。根据控制端C1接收到的切换信号，选择开关271中的选择端C2闭合时，将设置引脚ISET与第二电阻支路274相连；选择开关271中的选择端C2开启时，将设 置引脚ISET与第一电阻支路272相连。
示意性地，结合参考图3C，其示出了使用并联电路实现可调电阻支路270的结构示意图。可调电阻电路270包括选择开关271、并联的第三电阻RISET1和第四电阻RISET2；
第三电阻RISET1形成第一电阻支路272；第四电阻RISET2形成第二电阻支路274。第三电阻RISET1和第四电阻RISET2具有不同的阻值。
其中，第三电阻RISET1和第四电阻RISET2的一端接地。第三电阻RISET1和第四电阻RISET2的另一端通过选择开关271的选择端C2和设置引脚ISET相连。根据控制端C1接收到的切换信号，选择开关271中的选择端与第三电阻RISET1相连时，将设置引脚ISET与第一电阻支路272相连；选择开关271中的选择端与第四电阻RISET2相连时，将设置引脚ISET与第二电阻支路274相连。
本领域技术人员可以预见的是，可调电阻电路270的实现方式存在多种。本实施例中仅示意性的示出了可调电阻电路270的两种实现方式，但不对可调电阻电路270的具体实现方式作出限定。
根据公式二可知，在占空比的取值范围不变的情况下，参考电流的电流值发生改变后，驱动电流的电流值调节范围会增加，由图1所示的一个电流值调节范围[最小占空比*IFB_ful,最大占空比*IFB_ful]变为两个电流值调节范围[最小占空比1*I1,最大占空比1*I1]和[最小占空比2*I2，最大占空比2*I2]。I1是设置引脚ISET与第一电阻支路272相连时的参考电流，I2是设置引脚ISET与第二电阻支路274相连时的参考电流。
设第一电阻支路272的阻值为R1，第二电阻支路274的阻值为R2。
为了让电流值调节范围[最小占空比1*I1,最大占空比1*I1]中的最大驱动电流小于或等于电流值调节范围[最小占空比2*I2，最大占空比2*I2]中的最小驱动电流，也即，最大占空比1*I1≤最小占空比2*I2，结合公式1可知，R1和R2需要满足如下条件：
R1≥R2*最大占空比2/最小占空比1。
或者，为了让电流值调节范围[最小占空比1*I1,最大占空比1*I1]中的最小驱动电流大于或等于[最小占空比2*I2，最大占空比2*I2]中的最大驱动电流，也即，最小占空比1*I1≥最大占空比2*I2，结合公式1可知，R1和R2需要满足如下条件：
R1≤R2*最小占空比1/最大占空比2。
需要说明的是，最小占空比1和最小占空比2通常是相同的，均为1％。但是在可能的实施例中，最小占空比1和最小占空比2可以取不同的值，比如最小占空比1＝10％，最小占空比2＝1％。同理，最大占空比1和最大占空比2通常是相同的，均为100％。但是在可能的实施例中，最大占空比1和最大占空比2可以取不同的值，比如最大占空比1＝100％，最大占空比2＝90％。本实施例对此不加以限定，本实施例中仅以最小占空比1和最小占空比2是相同的，均为1％；最大占空比1和最大占空比2通常是相同的，均为100％来举例说明。
本实施例中以R1＝R2*最大占空比2/最小占空比1来举例说明。设VISET_full＝1.229V，KISET_full＝1030，R1＝6340K，R2＝63.4K。则与第一电阻支路272对应的电流值调节范围为[0.002mA,0.2mA]，与第二电阻支路274对应的电流值调节范围为[0.2mA,20mA]。
为了实现使用可调电阻电路270中的两个电阻支路来进行背光调节。存储器240中可以存储有三张对应表。这三张对应表分别是：期望亮度值与子表亮度值之间的总对应表、第一“子表亮度值-占空比”对应表和第二“子表亮度值-占空比”对应表。其中，第一“子表亮度值-占空比”对应表可简称为第一对应表；第二“子表亮度值-占空比”对应表可简称为第二对应表。容易理解的是，对应表只是为了说明对应关系，该对应表的表现形式也不限定为表。另外，本实施例中采用三张对应表也是为了方便理解和说明，但并不构成对其数量的限定，这三张对应表也可以集成在一张表上。
期望亮度值与子表亮度值之间的总对应表，可简称为总表。总表中的期望亮度值中的一部分取值区间内的期望亮度值与第一对应表中的子表亮度值对应，也即，一部分取值区间内的期望亮度值与第一电阻支路对应；总表中的期望亮度值中的另一部分取值区间内的期望亮度值与第二对应表中的子表亮度值对应，也即，另一部分取值区间内的期望亮度值与第二电阻支路对应。示意性的总表如表二所示：
表二
期望亮度值 第一对应表中的子表亮度值
0 0
1 2
2 4
3 6
…… ……
254 509
255 511
期望亮度值 第二对应表中的子表亮度值
256 0
257 2
258 4
259 6
…… ……
510 509
511 511
在表二中，当期望亮度值为0到255时与第一电阻支路对应，且此时期望亮度值与第一对应表中的子表亮度值之间的对应关系为：子表亮度值＝期望亮度值/255*511的取整值；当期望亮度值为256到511时与第二电阻支路对应，且此时期望亮度值与第二对应表中的子表亮度值的对应关系为：子表亮度值＝(期望亮度值-256)/255*511的取整值。
第一对应表是背光电源芯片260中的设置引脚ISET与第一电阻支路相连时，实际使用的“子表亮度值-占空比”对应表。示意性的第一对应表如表三所示。
表三
Figure PCTCN2015096869-appb-000002
第二“期望亮度值-占空比”对应表，可简称为第二对应表。第二对应表 是背光电源芯片220中的设置引脚与第二电阻支路相连时，所需要使用的“期望亮度值-占空比”对应表。示意性的第二对应表如表四所示。
表四
Figure PCTCN2015096869-appb-000003
背光控制器220调节背光时的具体方式如下：
在电子设备200开机时，背光控制器220从背光寄存器Reg_Iset中读取默认的期望亮度值(预先配置的值或上次关机时的值)。比如，该期望亮度值是259，该期望亮度值259在总表中与第二对应表中的子表亮度值6对应，也即该期望亮度值259与第二电阻支路274对应。则背光控制器220控制可调电阻电路270中的第二电阻支路274与设置引脚ISET相连。同时，背光控制器220在第二对应表中查询与子表亮度值6所对应的占空比为2.14％，则背光控制器220向背光电源芯片260的输入引脚IN发送占空比为2.14％的PWM信号。此时，背光电源芯片260中的参考电流为20mA，通过输出引脚OUT输出20*2.14％＝4.28mA的驱动电流，背光光源280根据4.28mA的驱动电流向外输出背光。
在电子设备200的工作过程中，可能存在三种因素导致期望亮度值发生变化：
第一，用户手动设置改变期望亮度值；
在电子设备的设置界面中提供有背光亮度的调节控件。该调节控件通常是拖动调节控件，包括一个按钮420和一个拖动条440，如图4所示。用户通过拖动按钮420位于拖动条440的不同位置，实现对期望亮度值的改变。
第二，应用程序根据自身的控制逻辑改变期望亮度值；
背光控制器220对期望亮度值的调节属于操作系统层级的控制，在操作系 统上还存在应用层，应用程运行有各种应用程序，比如：即时通信程序、电子书阅读程序、电话程序、短信息程序等。应用程序会根据自身的控制逻辑改变期望亮度值。比如，应用程序是电子书阅读程度，在夜间阅读模式下，将期望亮度值修改为50；又比如，应用程序是电话程序，在通话模式下，将期望亮度值修改为0。
第三，操作系统根据环境光强度改变期望亮度值。
电子设备上通常还设置有光传感器，通过光传感器采集环境光强度。操作系统能够根据环境光强度改变期望亮度值，比如：在环境光强度为A时，设置期望亮度值为100；在环境光强度为B时，设置期望亮度值为200。
本实施例中对期望亮度值的改变方式不做限定。
在一个可能的实施例中，默认的期望亮度值259被用户手动修改为258。则背光控制器220在总表中查询出与期望亮度值258对应的子表亮度值是第二对应表中的4，也即与期望亮度值258对应的电阻支路是第二电阻支路274。由于此时与设置引脚ISET相连的是第二电阻支路274，并不需要进行切换。背光控制器220在第二对应表中查询出与子表亮度值4对应的占空比为1.76％，则背光控制器220向背光电源芯片260的输入引脚IN发送占空比为1.76％的PWM信号。此时，背光电源芯片260中的参考电流为20mA，通过输出引脚OUT输出20*1.76％＝0.352mA的驱动电流，背光光源280根据0.352mA的驱动电流向外输出背光。
在另一个可能的实施例中，默认的期望亮度值259被用户手动修改为50。则背光控制器220在总表中查询出与期望亮度值50对应的子表亮度值是第一对应表中的100，也即与期望亮度值50对应的电阻支路是第一电阻支路272。由于此时与设置引脚ISET相连的是第二电阻支路274，所以背光控制器220需要将与设置引脚ISET相连的第二电阻支路274切换为第一电阻支路272。背光控制器220先向可调电阻电路270的控制端C1发送切换信号，可调电阻电路270在接收到切换信号后将设置引脚ISET与第一电阻支路272相连。背光控制器220再在第一对应表中查询出与子表亮度值100对应的占空比为20％，则背光控制器220向背光电源芯片260的输入引脚IN发送占空比为20％的PWM信号。此时，背光电源芯片260中的参考电流为0.2mA，通过输出引脚OUT输出0.2*20％＝0.04mA的驱动电流，背光光源280根据0.04mA的驱动电流向外输出背光。
如果期望亮度值又被用户手动从50修改为260，则背光控制器220在总表中查询出与期望亮度值260对应的子表亮度值是第二对应表中的8，也即与期望亮度值260对应的电阻支路是第二电阻支路274。由于此时与设置引脚ISET相连的是第一电阻支路272，所以背光控制器220需要将与设置引脚ISET相连的第一电阻支路272切换为第二电阻支路274。背光控制器220先向可调电阻电路270的控制端C1发送切换信号，可调电阻电路270在接收到切换信号后将第二电阻支路274与设置引脚ISET相连。背光控制器220再在第二对应表中查询出与子表亮度值8对应的占空比为2.52％，则背光控制器220向背光电源芯片260的输入引脚IN发送占空比为2.52％的PWM信号。此时，背光电源芯片260中的参考电流为20mA，通过输出引脚OUT输出20*2.52％＝0.504mA的驱动电流，背光光源280根据0.504mA的驱动电流向外输出背光。
但是工程师在试验中发现，将期望亮度值从50直接切换到260时，由于驱动电流是从0.04mA突变到0.504mA，改变幅度达到了十多倍，所以从用户来看，背光是闪烁后突然变亮的，背光的闪烁现象不仅刺激用户的眼睛，而且会加速损耗背光光源280的物理寿命。在更为优选的实施例中，驱动电流需要逐渐变化，以便用户的眼睛能够更好地适应背光变化过程，且保护背光光源280的物理寿命。
具体来讲，如果期望亮度值被用户手动从50修改为260，则背光控制器220在总表中查询出与期望亮度值50对应的子表亮度值是第一对应表中的100，与期望亮度值260对应的子表亮度值是第二对应表中的8。
背光控制器220在发送切换信号前，先将切换前当前输出的PWM信号的占空比逐渐增加至最大占空比1100％，具体如下：
背光控制器220先将子表亮度值从第一对应表中的100加1，得到子表亮度值101，从第一对应表中查询出与子表亮度值101对应的占空比为20.19％，向输入引脚IN发送占空比为20.19％的PWM信号，此时驱动电流为0.04038mA；
背光控制器220再将子表亮度值从第一对应表中的101加1，得到子表亮度值102，从第一对应表中查询出与子表亮度值102对应的占空比为20.38％，向输入引脚IN发送输出占空比为20.38％的PWM信号，此时驱动电流为0.04076mA；
背光控制器220再将子表亮度值从第一对应表中的102加1，得到子表亮 度值103，从第一对应表中查询出与子表亮度值103对应的占空比为20.57％，向输入引脚IN发送输出占空比为20.57％的PWM信号，此时驱动电流为0.04114mA；
依次类推，直至背光控制器220将子表亮度值逐次加1至第一对应表中的最大值511，输出占空比为100％的PWM信号，此时驱动电流为0.2mA，如图5所示。
背光控制器220在发送切换信号后，还需要将切换后输出的PWM信号的从最小占空比2逐渐增加至与期望亮度值260对应的占空比2.52％。具体如下：
在子表亮度值增大至第一对应表中的最大值511后，背光控制器220向可调电阻电路270的控制端C1发送切换信号，可调电阻电路270在接收到切换信号后将第二电阻支路274与设置引脚ISET相连。在从第一电阻支路272切换为第二电阻支路274后，背光控制器220将子表亮度值更新为第二对应表中的最小子表亮度值0，从第二对应表中查询出与子表亮度值0对应的占空比为最小占空比2＝1％，向输入引脚IN发送输出占空比为1％的PWM信号，此时驱动电流为0.2mA；
背光控制器220将子表亮度值从第二对应表中0加1后，得到子表亮度值1，从第二对应表中查询出与子表亮度值1对应的占空比为1.19％，向输入引脚IN发送输出占空比为1.19％的PWM信号，此时驱动电流为0.238mA；
依次类推，直至背光控制器220将子表亮度值逐次加1至第二对应表中的子表亮度值8，向输入引脚IN发送占空比为2.52％的PWM信号，此时驱动电流为0.504mA。
显然，驱动电流是从0.04mA、0.04038mA、0.04076mA，.......，0.2mA，0.238mA，……，逐渐增大至0.504mA。从用户角度来看，背光是逐渐变亮的。不仅没有闪烁现象，而且能够保护背光光源280的物理寿命。
同时，用户对暗光环境下的背光变化很敏感，但是由于第一对应表中的相邻两个驱动电流之间的调节步长是0.00038mA，第二对应表中的相邻两个驱动电流之间的调节步长是0.038mA，所以本发明实施例在较低背光亮度时的调节步长相比在较高背光亮度时的调节步长要小，用户不容易察觉到相邻两个驱动电流之间的变化。也即，在较低背光亮度时的背光渐变过程更加细腻和柔和。
需要说明的是，上述背光调节过程可以由较小的期望亮度值调节为较大的期望亮度值，也可以由较大的期望亮度值调节为较小的期望亮度值。
综上所述，本发明实施例提供的电子设备，通过将背光电源芯片的设置引脚与可调电阻电路相连，由可调电阻电路根据切换信号将与设置引脚相连的电阻支路从第一电阻支路切换为第二电阻支路，从而改变背光电源芯片中的参考电流，进而改变驱动电流的电流值调节范围；解决了受限于背光电源芯片的硬件性能，背光电源芯片只能在有限的电流值调节范围内输出驱动电流，导致背光LED输出的亮度也属于有限亮度范围；达到了通过不同电阻支路改变背光电源中的参考电流，从而实现在更多的电流值调节范围内输出驱动电流，使得背光强度达到更低亮度或更高亮度的效果。
本发明实施例提供的电子设备，还通过令R1＝R2*最大占空比2/最小占空比1，或者，R1＝R2*最小占空比1/最大占空比2，使得第一电阻支路对应的电流值调节范围和第二电阻支路对应的电流值调节范围能够合并为一个连续的电流值调节范围，从而实现一个变化范围较大的电流值调节范围。该变化范围较大的电流值调节范围使得将第一电阻支路和第二电阻支路之间进行切换时，没有闪烁现象。
本发明实施例提供的电子设备，还通过在期望亮度值从第一子表亮度值变化为第二子表亮度值的过程中，将第一子表亮度值逐渐加1或逐渐减1后渐变至第二子表亮度值，使得驱动电流是逐渐变化的，背光也是逐渐变化的，以便用户的眼睛能够更好地适应背光变化过程，而且保护背光光源的物理寿命。
本发明实施例提供的电子设备，还通过在较低的电流值调节范围内，让相邻两个驱动电流之间的调节步长更小，使得即便用户对暗光环境下的背光变化很敏感，也不容易察觉到相邻两个驱动电流之间的变化。也即，在较低背光亮度时的背光渐变过程更加细腻和柔和。
结合图5可知，由于第一对应表和第二对应表都存在512个子表亮度值，所以背光控制器220具有在1024个亮度级别上调节背光亮度的能力。但是存储器240中需要存储三个表：总表、第一对应表和第二对应表。在可选的实施例中，总表、第一对应表和第二对应表能够整合为一个表。若背光寄存器依然为9比特，则该表如表五所示：
表五
期望亮度值 占空比
0 1％
1 1.38％
2 1.76％
3 2.14％
… …
255 100％
256 0％
… …
511 100％
此时，相邻两个占空比之间的调节步长从0.19％改变为0.38，背光控制器220仅可以在512个亮度级别上调节背光亮度。其中，期望亮度值[0，255]对应的电阻支路是第一电阻支路，期望亮度值[256，511]对应的电阻支路是第二电阻支路。
需要说明的是，由于第一电阻支路的阻值R1和第二电阻支路的阻值R2不同，第一电阻支路所对应的电流值调节范围和第二电阻支路所对应的电流值调节范围，可能存在三种情况：
第一，两个电流值调节范围互不相交。此时，R1＞R2*最大占空比2/最小占空比1；或者，R1＜R2*最小占空比1/最大占空比2。比如，第一电阻电路272所对应的电流值调节范围是[0.0015mA，0.15mA]，第二电阻支路274所对应的电流值调节范围是[0.16mA，16mA]。可选地，当两个电流值调节范围之间的范围较小时，比如0.15mA和0.16mA之间仅相差0.01mA时，两个电阻支路切换时的驱动电流跳变比较弱，用户难以观察到该跳变。
第二，两个电流值调节范围在边界值上相交。此时，R1＝R2*最大占空比2/最小占空比1；或者，R1＝R2*最小占空比1/最大占空比2。比如，第一电阻电路272所对应的电流值调节范围是[0.0015mA，0.15mA]，第二电阻支路274所对应的电流值调节范围是[0.15mA，15mA]。两个电阻支路切换时的驱动电流不存在跳变，也即两个电流值调节范围可以连接成为一个连续的电流值调节范围。
第三，两个电流值调节范围在一段区间上相交，比如，第一电阻电路所对应的电流值调节范围是[0.0015mA，0.15mA]，第二电阻支路所对应的电流值调节范围是[0.10mA，10mA]。此时，通过预先在对应表中改变某一个电流值调 节范围的最小占空比和/或最大占空比，能够使得两个电流值调节范围互不相交，或者仅在边界值上相交。比如，通过改变第二电阻支路的最小占空比，使得第二电阻支路所对应的电流值调节范围变为[0.15mA，10mA]。
对上述背光控制器进行背光调节时的方法进行总结。请参考图6，其示出了本发明一个实施例提供的背光调节方法的方法流程图。该方法可以由如上图2所示实施例中提供的背光控制器220执行。该方法包括:
步骤601，获取期望亮度值，期望亮度值用于表示期望背光光源发出的背光亮度；
在电子设备开机时，期望亮度值为默认的期望亮度值；
在电子设备运行过程中，期望亮度值的改变包括但不限于如下三种方式：
第一，用户手动设置改变期望亮度值；
第二，应用程序根据自身的控制逻辑改变期望亮度值；
第三，操作系统根据环境光强度改变期望亮度值。
步骤602，确定与期望亮度值对应的电阻支路，电阻支路是第一电阻支路和第二电阻支路中的一个；
背光控制器通过查询表二示出的总表，或者表五示出的对应表，确定出与期望亮度值对应的电阻支路。
步骤603，当与期望亮度值对应的电阻支路和与设置引脚相连的电阻支路不同时，向可调电阻电路的控制端发送切换信号；
步骤604，向背光电源芯片发送PWM信号，该PWM信号的占空比与期望亮度值对应；
背光控制器通过查询表三示出的第一对应表，或者查询表四示出的第二对应表，或者表五示出的对应表，确定与该期望亮度值对应的占空比。然后，背光控制器向背光电源芯片的输入引脚IN发送符合该占空比的PWM信号。
背光电源芯片用于以参考电流为基准，根据PWM信号的占空比生成驱动电流，向背光光源发送驱动电流，背光光源用于根据驱动电流发出背光。
综上所述，本实施例提供的背光调节方法，通过由背光控制器获取期望亮度值，在与期望亮度值对应的电阻支路和与设置引脚相连的电阻支路不同时，向可调电阻电路的控制端发送切换信号，由可调电阻电路根据切换信号将与设置引脚相连的电阻支路在第一电阻支路和第二电阻支路之间切换，从而改变背 光电源芯片中的参考电流，由于驱动电流是基于参考电流产生的，所以进而会改变驱动电流的电流值调节范围；解决了受限于背光电源芯片的硬件性能，背光电源芯片只能在有限的电流值调节范围内输出驱动电流，导致背光光源输出的亮度也属于有限亮度范围的问题；达到了通过不同电阻支路改变背光电源中的参考电流，从而实现在更大的电流值调节范围内输出驱动电流，使得背光强度达到更低亮度或更高亮度的效果。
为了使背光亮度不发生突变，避免闪烁现象的产生，背光控制器还可以在背光切换过程中对驱动电流进行渐变调节。
由于存在R1＞R2，R1＜R2两种阻值情形，以及将较小的期望亮度值调节为较大的期望亮度值，将较大的期望亮度值调节为较小的期望亮度值两种调节情形，总共有四种可能的实施例：
第一种实施例，R1＞R2，从与第一电阻支路对应的一个较小的期望亮度值，调节至与第二电阻支路对应的一个较大的期望亮度值；
第二种实施例，R1＜R2，从与第一电阻支路对应的一个较大的期望亮度值，调节至与第二电阻支路对应的一个较小的期望亮度值；
第三种实施例，R1＞R2，从与第二电阻支路对应的一个较大的期望亮度值，调节至与第一电阻支路对应的一个较小的期望亮度值；
第四种实施例，R1＜R2，从与第二电阻支路对应的一个较小的期望亮度值，调节至与第一电阻支路对应的一个较大的期望亮度值。
请参考图7A，其示出了本发明另一个实施例提供的背光调节方法的流程图。该方法可以由如上图2所示实施例中提供的背光控制器220执行，用于实现上述第一种实施例的背光调节。该方法包括:
步骤701，获取期望亮度值，期望亮度值用于表示期望背光光源发出的背光亮度；
在电子设备开机时，期望亮度值为默认的期望亮度值；
在电子设备运行过程中，期望亮度值的改变包括但不限于如下三种方式：
第一，用户手动设置改变期望亮度值；
第二，应用程序根据自身的控制逻辑改变期望亮度值；
第三，操作系统根据环境光强度改变期望亮度值。
步骤702，确定与期望亮度值对应的电阻支路，电阻支路是第一电阻支路和第二电阻支路中的一个；
背光控制器通过查询表二示出的总表，或者表五示出的对应表，确定出与期望亮度值对应的电阻支路。
步骤703，当与期望亮度值对应的电阻支路和与设置引脚相连的电阻支路不同，与设置引脚相连的电阻支路是第一电阻支路且第一电阻支路的阻值大于第二电阻支路的阻值时，将当前输出的PWM信号的占空比逐渐增加至最大占空比1；
最大占空比1是设置引脚与第一电阻支路相连时的最大占空比。
背光控制器将当前输出的PWM信号的占空比逐渐增加至最大占空比1时所使用的调节步长不限。该调节步长可以是两个相邻的子表亮度值对应的占空比之差，比如表三或表四中示出的0.19％；也可以是两个相邻的期望亮度值对应的占空比之差，比如表五中示出的0.38％，或者其它可能的值。
步骤704，向可调电阻电路的控制端发送切换信号；
在与设置引脚相连的电阻支路是第一电阻支路时，该切换信号用于触发可调电阻电路将第二电阻支路与设置引脚相连；
在与设置引脚相连的电阻支路是第二电阻支路时，该切换信号用于触发可调电阻电路将第一电阻支路与设置引脚相连。
步骤705，查询与期望亮度值对应的占空比；
背光控制器在总表、第一对应表和第二对应表中查询与期望亮度值对应的占空比；或者，背光控制器在表五示出的对应表中查询出与期望亮度值对应的占空比。
步骤706，在切换后与设置引脚相连的电阻支路是第二电阻支路且第一电阻支路的阻值大于第二电阻支路的阻值时，将当前输出的PWM信号从最小占空比2逐渐增加至与期望亮度值对应的占空比；
最小占空比2是设置引脚与第二电阻支路相连时的最小占空比。
背光控制器将当前输出的PWM信号最小占空比2逐渐增加至与期望亮度值对应的占空比时所使用的调节步长不限。该调节步长可以是两个相邻的子表亮度值对应的占空比之差，比如表三或表四中示出的0.19％；也可以是两个相邻的期望亮度值对应的占空比之差，比如表五中示出的0.38％，或者其它可能的值。
综上所述，本实施例提供的背光调节方法，通过步骤703能够使得PWM信号在发送切换信号之前是逐渐变化的，不会引发背光亮度的突变，避免背光亮度的闪烁现象。通过步骤706能够使得PWM信号在发送切换信号之后是逐渐变化的，不会引发背光亮度的突变，避免背光亮度的闪烁现象。
同理，对于第二种实施例，可将上述步骤703可替代实现成为步骤703a，将上述步骤706可替代实现成为步骤706a，如图7B所示：
步骤703a，当与期望亮度值对应的电阻支路和与设置引脚相连的电阻支路不同，与设置引脚相连的电阻支路是第一电阻支路且第一电阻支路的阻值小于第二电阻支路的阻值时，将当前输出的PWM信号的占空比逐渐减小至最小占空比1。
最小占空比1是设置引脚与第一电阻支路相连时的最大占空比。
步骤706a，在切换后与设置引脚相连的电阻支路是第二电阻支路且第一电阻支路的阻值小于第二电阻支路的阻值时，将当前输出的PWM信号从最大占空比2逐渐减小至与期望亮度值对应的占空比。
最大占空比2是设置引脚与第二电阻支路相连时的最大占空比。
同理，对于第三种实施例，可将上述步骤703可替代实现成为步骤703b，将上述步骤706可替代实现成为步骤706b，如图7c所示：
步骤703b，当与期望亮度值对应的电阻支路和与设置引脚相连的电阻支路不同，与设置引脚相连的电阻支路是第二电阻支路且第一电阻支路的阻值大于第二电阻支路的阻值时，将当前输出的PWM信号的占空比逐渐减小至最小占空比2。
最小占空比2是设置引脚与第二电阻支路相连时的最小占空比。
步骤706b，在切换后与设置引脚相连的电阻支路是第一电阻支路且第一电阻支路的阻值大于第二电阻支路的阻值时，将当前输出的PWM信号从最大占空比1逐渐减小至与期望亮度值对应的占空比。
最大占空比1是设置引脚与第二电阻支路相连时的最大占空比。
同理，对于第四种实施例，可将上述步骤703可替代实现成为步骤703c，将上述步骤706可替代实现成为步骤706c，如图7C所示：
步骤703c，当与期望亮度值对应的电阻支路和与设置引脚相连的电阻支路不同，与设置引脚相连的电阻支路是第二电阻支路且第一电阻支路的阻值小于第二电阻支路的阻值时，将当前输出的PWM信号的占空比逐渐增大至最大占空比2。
最大占空比2是设置引脚与第二电阻支路相连时的最大占空比。
步骤706c，在切换后与设置引脚相连的电阻支路是第一电阻支路且第一电阻支路的阻值小于第二电阻支路的阻值时，将当前输出的PWM信号的最小占空比1逐渐增大至与期望亮度值对应的占空比。
最小占空比1是设置引脚与第二电阻支路相连时的最小占空比。
本领域普通技术人员可以理解实现上述实施例的全部或部分步骤可以通过硬件来完成，也可以通过程序来指令相关的硬件完成，所述的程序可以存储于一种计算机可读存储介质中，上述提到的存储介质可以是只读存储器，磁盘或光盘等。
以上所述仅为本发明的较佳实施例，并不用以限制本发明，凡在本发明的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。

Claims (13)

  1. 一种背光电路，其特征在于，所述背光电路包括：背光电源芯片和可调电阻电路；
    所述背光电源芯片，包括：用于设置参考电流的设置引脚、输入引脚和输出引脚；
    所述可调电阻电路的一端与所述设置引脚相连，所述可调电阻电路的另一端接地，所述可调电阻电路包括第一电阻支路和第二电阻支路，所述第一电阻支路和所述第二电阻支路具有不同的电阻值，用于产生不同的所述参考电流；
    所述可调电阻电路包括：控制端，所述控制端用于接收切换信号，根据所述切换信号将与所述设置引脚相连的电阻支路在所述第一电阻支路和所述第二电阻支路之间切换；
    所述背光电源芯片，用于以所述参考电流为基准，根据所述输入引脚接收到的脉宽调制PWM信号的占空比生成驱动电流；通过所述输出引脚输出所述驱动电流，所述驱动电流用于驱动背光光源发送背光。
  2. 根据权利要求1所述的背光电路，其特征在于，所述可调电阻电路包括：选择开关和至少两条电阻支路；所述至少两条电阻支路中的任意一条电阻支路为所述第一电阻支路，所述至少两条电阻支路中的另一条电阻支路为所述第二电阻支路；
    所述选择开关包括：所述控制端和选择端；
    所述选择端，用于根据所述控制端接收到的所述切换信号，根据所述切换信号将与所述设置引脚相连的电阻支路在所述第一电阻支路和所述第二电阻支路之间切换。
  3. 根据权利要求2所述的背光电路，其特征在于，所述可调电阻电路包括串联的第一电阻和第二电阻；
    所述第一电阻和所述第二电阻形成所述第一电阻支路；所述第二电阻形成所述第二电阻支路；
    或，
    所述第一电阻和所述第二电阻形成所述第二电阻支路；所述第二电阻形成 所述第一电阻支路。
  4. 根据权利要求2所述的背光电路，其特征在于，所述可调电阻电路包括并联的第三电阻和第四电阻；
    所述第三电阻形成所述第一电阻支路；
    所述第四电阻形成所述第二电阻支路。
  5. 根据权利要求1至4任一所述的背光电路，其特征在于，所述第一电阻支路的阻值R1和所述第二电阻支路的阻值R2满足如下条件：
    R1≥R2*最大占空比2/最小占空比1；
    或者，R1≤R2*最小占空比1/最大占空比2；
    其中，所述最小占空比1是所述设置引脚与所述第一电阻支路相连时的最小占空比；所述最大占空比1是所述设置引脚与所述第一电阻支路相连时的最大占空比；所述最小占空比2是所述设置引脚与所述第二电阻支路相连时的最小占空比；所述最大占空比2是所述设置引脚与所述第二电阻支路相连时的最大占空比。
  6. 根据权利要求1至4任一所述的背光电路，其特征在于，所述切换信号是背光控制器在与期望亮度值对应的电阻支路和与所述设置引脚相连的电阻支路不同时发送的；
    所述期望亮度值用于表示期望所述背光光源发出的背光亮度。
  7. 一种电子设备，其特征在于，所述电子设备包括：背光控制器、存储器、如权利要求1至6任一所述的背光电路和背光光源；所述存储器与所述背光控制器相连，所述存储器存储有所述背光控制器的可执行程序；
    所述背光控制器与所述背光电路中的所述背光电源芯片的所述输入引脚相连，用于向所述背光电源芯片发送所述脉宽调制PWM信号；所述背光控制器还与所述背光电路中的所述可调电阻电路的所述控制端相连，用于向所述可调电阻电路发送所述切换信号；
    所述背光电路中的所述背光电源芯片的所述输出引脚与所述背光光源相连；所述背光光源用于根据所述驱动电流发出背光。
  8. 根据权利要求7所述的电子设备，其特征在于，所述背光控制器是：中央处理器CPU或图像处理器GPU或液晶屏驱动集成电路Drive IC。
  9. 根据权利要求7所述的电子设备，其特征在于，所述背光控制器用于：
    获取期望亮度值，所述期望亮度值用于表示期望所述背光光源发出的背光亮度；
    确定与所述期望亮度值对应的电阻支路，所述电阻支路是所述第一电阻支路和所述第二电阻支路中的一个；
    当与所述期望亮度值对应的电阻支路和与所述设置引脚相连的电阻支路不同时，向所述可调电阻电路的控制端发送所述切换信号；
    所述背光控制器，还用于向所述背光电源芯片发送所述PWM信号，所述PWM信号的占空比与所述期望亮度值对应。
  10. 根据权利要求9所述的电子设备，其特征在于，
    所述背光控制器，还用于在向所述可调电阻电路的控制端发送所述切换信号之前，若与所述设置引脚相连的电阻支路是所述第一电阻支路且所述第一电阻支路的阻值大于所述第二电阻支路的阻值时，将当前输出的PWM信号的占空比逐渐增加至最大占空比1，所述最大占空比1是所述设置引脚与所述第一电阻支路相连时的最大占空比；
    或，
    所述背光控制器，还用于在向所述可调电阻电路的控制端发送所述切换信号之前，若与所述设置引脚相连的电阻支路是所述第一电阻支路且所述第一电阻支路的阻值小于所述第二电阻支路的阻值时，将当前输出的PWM信号的占空比逐渐减小至最小占空比1，所述最小占空比1是所述设置引脚与所述第一电阻支路相连时的最小占空比；
    或，
    所述背光控制器，还用于在向所述可调电阻电路的控制端发送所述切换信号之前，若与所述设置引脚相连的电阻支路是所述第二电阻支路且所述第一电阻支路的阻值大于所述第二电阻支路的阻值时，将当前输出的PWM信号的占空比逐渐减小至最小占空比2，所述最小占空比2是所述设置引脚与所述第二电阻 支路相连时的最小占空比；
    或，
    所述背光控制器，还用于在向所述可调电阻电路的控制端发送所述切换信号之前，若与所述设置引脚相连的电阻支路是所述第二电阻支路且所述第一电阻支路的阻值小于所述第二电阻支路的阻值时，将当前输出的PWM信号的占空比逐渐增大至最大占空比2，所述最大占空比2是所述设置引脚与所述第二电阻支路相连时的最大占空比。
  11. 根据权利要求9所述的电子设备，其特征在于，
    所述背光控制器，还用于查询与所述期望亮度值对应的所述占空比；在切换后与所述设置引脚相连的电阻支路是所述第二电阻支路且所述第一电阻支路的阻值大于所述第二电阻支路的阻值时，将当前输出的所述PWM信号从最小占空比2逐渐增加至所述占空比，所述最小占空比2是所述设置引脚与所述第二电阻支路相连时的最小占空比；
    或，
    所述背光控制器，还用于查询与所述期望亮度值对应的所述占空比；在切换后与所述设置引脚相连的电阻支路是所述第二电阻支路且所述第一电阻支路的阻值小于所述第二电阻支路的阻值时，将当前输出的所述PWM信号从最大占空比2逐渐减小至所述占空比，所述最大占空比2是所述设置引脚与所述第二电阻支路相连时的最大占空比；
    或，
    所述背光控制器，还用于查询与所述期望亮度值对应的所述占空比；在切换后与所述设置引脚相连的电阻支路是所述第一电阻支路且所述第一电阻支路的阻值大于所述第二电阻支路的阻值时，将当前输出的所述PWM信号从最大占空比1逐渐减小至所述占空比，所述最大占空比1是所述设置引脚与所述第一电阻支路相连时的最大占空比；
    或，
    所述背光控制器，还用于查询与所述期望亮度值对应的所述占空比；在切换后与所述设置引脚相连的电阻支路是所述第一电阻支路且所述第一电阻支路的阻值小于所述第二电阻支路的阻值时，将当前输出的所述PWM信号从最小占空比1逐渐增大至所述占空比，所述最小占空比1是所述设置引脚与所述第一电 阻支路相连时的最小占空比。
  12. 根据权利要求7至11任一所述的电子设备，其特征在于，所述第一电阻支路的阻值R1和所述第二电阻支路的阻值R2满足如下条件：
    R1≥R2*最大占空比2/最小占空比1；
    或者，R1≤R2*最小占空比1/最大占空比2；
    其中，所述最小占空比1是所述设置引脚与所述第一电阻支路相连时的最小占空比；所述最大占空比1是所述设置引脚与所述第一电阻支路相连时的最大占空比；所述最小占空比2是所述设置引脚与所述第二电阻支路相连时的最小占空比；所述最大占空比2是所述设置引脚与所述第二电阻支路相连时的最大占空比。
  13. 一种背光调节方法，其特征在于，应用于如权利要求7或8所述的电子设备的背光控制器中，所述方法包括：
    获取期望亮度值，所述期望亮度值用于表示期望所述背光光源发出的背光亮度；
    确定与所述期望亮度值对应的电阻支路，所述电阻支路是所述第一电阻支路和所述第二电阻支路中的一个；
    当与所述期望亮度值对应的电阻支路和与所述设置引脚相连的电阻支路不同时，向所述可调电阻电路的控制端发送切换信号；
    向所述背光电源芯片发送所述PWM信号，所述PWM信号的占空比与所述期望亮度值对应；所述背光电源芯片用于以所述参考电流为基准，根据所述PWM信号的占空比生成驱动电流，向所述背光光源发送所述驱动电流，所述背光光源用于根据所述驱动电流发出背光。
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