WO2022077766A1 - 背光恒流控制电路和背光结构 - Google Patents

背光恒流控制电路和背光结构 Download PDF

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Publication number
WO2022077766A1
WO2022077766A1 PCT/CN2020/139008 CN2020139008W WO2022077766A1 WO 2022077766 A1 WO2022077766 A1 WO 2022077766A1 CN 2020139008 W CN2020139008 W CN 2020139008W WO 2022077766 A1 WO2022077766 A1 WO 2022077766A1
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WIPO (PCT)
Prior art keywords
electrically connected
unit
switch unit
transistor
backlight
Prior art date
Application number
PCT/CN2020/139008
Other languages
English (en)
French (fr)
Inventor
刘金风
Original Assignee
Tcl华星光电技术有限公司
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Publication of WO2022077766A1 publication Critical patent/WO2022077766A1/zh

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Classifications

    • 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
    • G09G3/3406—Control of illumination source
    • G09G3/3413—Details of control of colour illumination sources
    • 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]
    • H05B45/30—Driver circuits
    • H05B45/32—Pulse-control circuits
    • H05B45/325—Pulse-width modulation [PWM]
    • 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]
    • H05B45/30—Driver circuits
    • H05B45/345—Current stabilisation; Maintaining constant current
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/40—Control techniques providing energy savings, e.g. smart controller or presence detection

Definitions

  • the present application relates to the field of display technology, in particular to the field of display drive technology, and in particular to a backlight constant current control circuit and a backlight structure.
  • Mini LED With the development of technology, a kind of Mini LED with ultra-small process structure has been mass-produced in small batches. Due to its small structure, LED can realize more partitions. Compared with traditional LCD display technology, Mini LED backlight has more backlight partitions, which makes the TV picture quality more refined, lower energy consumption, more detailed picture, and more obvious contrast. .
  • the existing Mini LED backlight adopts the local dimming backlight realized by the active address driving (AM: ActiveMatrix, also known as active addressing, active addressing, active driving, etc.) scheme, and each partition is composed of multiple LED lights connected in series , using constant voltage control mode (that is, VDD voltage is fixed) to drive each partition to work, when there is an LED lamp in the circuit fault and short circuit, the total resistance of the LED lamp string in the partition becomes smaller, because the voltage at both ends of the LED lamp string does not change , so that the current of the LED light string in this partition becomes larger, and the LED lights are extremely sensitive to current, the display brightness of this partition will be greater than other partitions, or greater than the required brightness, resulting in uneven brightness of the entire backlight, which greatly affects the display. Effect.
  • A ActiveMatrix, also known as active addressing, active addressing, active driving, etc.
  • the present application provides a backlight constant current control circuit and a backlight structure.
  • constant current control By performing constant current control on the light emitting module, it is possible to avoid affecting the current of the light emitting module after a device in the light emitting module is short-circuited, which is beneficial to keep the current of the light emitting module at a preset value.
  • the current keeps the luminous brightness of the light-emitting module at the preset luminous brightness, thereby ensuring the stability and uniform distribution of the backlight brightness, which is beneficial to improve the display effect.
  • the application provides a backlight constant current control circuit, including a light emitting module and a constant current control module;
  • the constant current control module includes a first switch unit; the constant current control module is used to adjust the conduction time and conduction of the first switch unit when detecting that the working current of the light emitting module deviates from the preset current to adjust the working current of the light-emitting module to the preset current, so that the light-emitting brightness of the light-emitting module is maintained at the preset light-emitting brightness.
  • the constant current control module further includes a feedback unit and a sampling unit;
  • the sampling unit is electrically connected to the first switch unit
  • the feedback unit is electrically connected to the sampling unit and the first switch unit, respectively, and is used for detecting the voltage across the sampling unit, and when detecting that the voltage across the sampling unit deviates from a preset voltage, determine the The operating current of the light emitting module deviates from the preset current, and the conduction time and the degree of conduction of the first switch unit are adjusted to adjust the operating current of the light emitting module to the preset current.
  • the feedback unit includes a level converter, a first PWM controller and a comparator;
  • the comparator is electrically connected to the sampling unit and the first PWM controller respectively, and is used for detecting the voltage across the sampling unit and comparing the voltage across the sampling unit with the preset voltage; When the voltage across the sampling unit deviates from the preset voltage, determining that the operating current of the light-emitting module deviates from the preset current, and outputting a level signal to the first PWM controller according to the degree of deviation;
  • the first PWM controller is also electrically connected to the level shifter, and is configured to output a duty cycle signal to the level shifter according to the level signal;
  • the level converter is also electrically connected to the first switch unit, and is used to adjust the level of the duty cycle signal, and adjust the level of the first switch unit through the adjusted duty cycle signal. On-time and on-degree.
  • the first switch unit includes a first transistor, and the sampling unit includes a sampling resistor;
  • the drain of the first transistor is electrically connected to the output end of the light-emitting module, the source of the first transistor is grounded through the sampling resistor, and the gate of the first transistor is connected to the level shifter.
  • the output terminal is electrically connected;
  • the input terminal of the comparator is electrically connected to the source of the first transistor, and the output terminal of the comparator is electrically connected to the input terminal of the first PWM controller;
  • the output end of the first PWM controller is electrically connected to the input end of the level conversion.
  • the light emitting module includes a plurality of LEDs arranged in series.
  • the backlight constant current control circuit further includes a boosting module electrically connected to the input end of the light emitting module;
  • the boosting module includes a charge and discharge unit, a second switch unit and a third switch unit; the charge and discharge unit is electrically connected to the second switch unit and the third switch unit, respectively;
  • the boosting module is used to adjust the on-time of the second switch unit and the third switch unit according to the preset light-emitting brightness; when the second switch unit is on, the charging and discharging unit is charged , and the charging and discharging unit is discharged when the third switching unit is turned on, so as to output a preset power supply voltage to the input end of the light-emitting module.
  • the boosting module further includes a driver and a second PWM controller;
  • the charging and discharging unit includes an inductor, the second switching unit includes a second transistor, and the first The three-switch unit includes a third transistor;
  • the second PWM controller is electrically connected to the input terminal of the driver; the input terminal of the driver is electrically connected to the second PWM controller, and the output terminal of the driver is respectively connected to the gate of the second transistor is electrically connected to the gate of the third transistor;
  • One end of the inductor is connected to the input voltage, and the other end is electrically connected to the drain electrode of the second transistor and the source electrode of the third transistor respectively, the source electrode of the second transistor is grounded, and the source electrode of the third transistor is grounded.
  • the drain is electrically connected to the input end of the light emitting module.
  • the boosting module further includes a first capacitor and a second capacitor; one end of the first capacitor is electrically connected to an end of the inductor far away from the second transistor, The other end is grounded; one end of the second capacitor is electrically connected to the input end of the light-emitting module, and the other end is grounded.
  • the present application also provides a backlight structure, comprising a plurality of the above-mentioned backlight constant current control circuits; the backlight structure includes at least one backlight sub-region, and each of the backlight sub-regions is provided with at least one light-emitting module of the backlight constant current control circuit .
  • a plurality of the constant current control modules in the plurality of the backlight constant current control circuits are integrated and arranged in the same control chip.
  • the backlight constant current control circuit further includes a boosting module electrically connected to the input end of the light-emitting module, and the boosting module is also integrated in the control chip.
  • the boosting module includes a charge and discharge unit, a second switch unit and a third switch unit; the charge and discharge unit is respectively connected with the second switch unit and the third switch unit electrical connection;
  • the boosting module is used to adjust the on-time of the second switch unit and the third switch unit according to the preset light-emitting brightness; when the second switch unit is on, the charging and discharging unit is charged , and the charging and discharging unit is discharged when the third switching unit is turned on, so as to output a preset power supply voltage to the input end of the light-emitting module.
  • the constant current control module corresponding to each of the backlight partitions is provided in an independent control chip.
  • the constant current control module further includes a feedback unit and a sampling unit;
  • the sampling unit is electrically connected to the first switch unit
  • the feedback unit is electrically connected to the sampling unit and the first switch unit, respectively, and is used for detecting the voltage across the sampling unit, and when detecting that the voltage across the sampling unit deviates from a preset voltage, determine the The operating current of the light emitting module deviates from the preset current, and the conduction time and the degree of conduction of the first switch unit are adjusted to adjust the operating current of the light emitting module to the preset current.
  • the feedback unit includes a level converter, a first PWM controller and a comparator
  • the comparator is electrically connected to the sampling unit and the first PWM controller respectively, and is used for detecting the voltage across the sampling unit and comparing the voltage across the sampling unit with the preset voltage; When the voltage across the sampling unit deviates from the preset voltage, determining that the operating current of the light-emitting module deviates from the preset current, and outputting a level signal to the first PWM controller according to the degree of deviation;
  • the first PWM controller is also electrically connected to the level shifter, and is configured to output a duty cycle signal to the level shifter according to the level signal;
  • the level converter is also electrically connected to the first switch unit, and is used to adjust the level of the duty cycle signal, and adjust the level of the first switch unit through the adjusted duty cycle signal. On-time and on-degree.
  • the first switch unit includes a first transistor, and the sampling unit includes a sampling resistor;
  • the drain of the first transistor is electrically connected to the output end of the light-emitting module, the source of the first transistor is grounded through the sampling resistor, and the gate of the first transistor is connected to the level shifter.
  • the output terminal is electrically connected;
  • the input terminal of the comparator is electrically connected to the source of the first transistor, and the output terminal of the comparator is electrically connected to the input terminal of the first PWM controller;
  • the output end of the first PWM controller is electrically connected to the input end of the level conversion.
  • the light emitting module includes a plurality of LEDs arranged in series.
  • the backlight constant current control circuit further includes a boosting module electrically connected to the input end of the light emitting module;
  • the boosting module includes a charge and discharge unit, a second switch unit and a third switch unit; the charge and discharge unit is electrically connected to the second switch unit and the third switch unit, respectively;
  • the boosting module is used to adjust the on-time of the second switch unit and the third switch unit according to the preset light-emitting brightness; when the second switch unit is on, the charging and discharging unit is charged , and the charging and discharging unit is discharged when the third switching unit is turned on, so as to output a preset power supply voltage to the input end of the light-emitting module.
  • the boosting module further includes a driver and a second PWM controller;
  • the charging and discharging unit includes an inductor, the second switching unit includes a second transistor, and the third switching unit including a third transistor;
  • the second PWM controller is electrically connected to the input terminal of the driver; the input terminal of the driver is electrically connected to the second PWM controller, and the output terminal of the driver is respectively connected to the gate of the second transistor is electrically connected to the gate of the third transistor;
  • One end of the inductor is connected to the input voltage, and the other end is electrically connected to the drain electrode of the second transistor and the source electrode of the third transistor respectively, the source electrode of the second transistor is grounded, and the source electrode of the third transistor is grounded.
  • the drain is electrically connected to the input end of the light emitting module.
  • the boosting module further includes a first capacitor and a second capacitor; one end of the first capacitor is electrically connected to one end of the inductor away from the second transistor, and the other end is grounded ; One end of the second capacitor is electrically connected to the input end of the light-emitting module, and the other end is grounded.
  • the constant current control module includes a first switch unit electrically connected with the light emitting module; when the constant current control module detects that the working current of the light emitting module deviates from the preset current, it can adjust the The conduction time and conduction degree of the first switch unit can adjust the lighting time of the lighting module and the voltage division of the lighting module, so that the working current (average current) of the lighting module can be adjusted, so that the working current of the lighting module is equal to the preset current, Therefore, the light-emitting brightness of the light-emitting module can be maintained at the preset light-emitting brightness, which avoids the problem of uneven brightness of the backlight structure caused by the current fluctuation of the light-emitting module, and is beneficial to improve the stability of the backlight brightness; when the backlight constant current control circuit and the backlight structure are applied When used in a display device, it is beneficial to improve the display effect.
  • FIG. 1 is a schematic block diagram of a backlight constant current control circuit provided by an embodiment of the present application.
  • FIG. 2 is a schematic circuit diagram of a backlight constant current control circuit provided by an embodiment of the present application.
  • FIG. 3a is a schematic diagram of a backlight structure provided by an embodiment of the present application.
  • FIG. 3b is a schematic diagram of another backlight structure provided by an embodiment of the present application.
  • first and second are only used for descriptive purposes, and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, features defined as “first”, “second” may expressly or implicitly include one or more of said features. In the description of the present application, “plurality” means two or more, unless otherwise expressly and specifically defined.
  • the terms “installed”, “connected” and “connected” should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection Connection, or integral connection; it can be mechanical connection, electrical connection or can communicate with each other; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal communication of two elements or the interaction of two elements relation.
  • installed should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection Connection, or integral connection; it can be mechanical connection, electrical connection or can communicate with each other; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal communication of two elements or the interaction of two elements relation.
  • a first feature "on” or “under” a second feature may include direct contact between the first and second features, or may include the first and second features Not directly but through additional features between them.
  • the first feature being “above”, “over” and “above” the second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is level higher than the second feature.
  • the first feature is “below”, “below” and “below” the second feature includes the first feature being directly below and diagonally below the second feature, or simply means that the first feature has a lower level than the second feature.
  • an embodiment of the present application provides a backlight constant current control circuit 1, and the backlight constant current control circuit 1 includes a light-emitting module 2 and a constant current control module 3; wherein, the constant current control module 3 includes and A first switch unit 4 arranged in series with the light emitting module 2; the constant current control module 3 is used to adjust the conduction time and conduction degree of the first switch unit 4 when detecting that the working current of the light emitting module 2 deviates from the preset current, so as to The operating current of the light-emitting module 2 is adjusted to a preset current, so that the light-emitting brightness of the light-emitting module 2 is maintained at the preset light-emitting brightness.
  • the light-emitting brightness of the light-emitting module 2 is controlled by the working current; wherein, the working current is the actual current when the light-emitting module 2 emits light, and the preset current is the flow rate of the light-emitting module 2 when the light-emitting module 2 is preset to emit light.
  • the working current is the actual current when the light-emitting module 2 emits light
  • the preset current is the flow rate of the light-emitting module 2 when the light-emitting module 2 is preset to emit light.
  • the magnitude of the current passing through the light-emitting module 2 therefore, the preset current can be obtained according to the preset light-emitting brightness.
  • the light emitting module 2 includes a plurality of LEDs arranged in series, specifically, a plurality of Mini-LEDs arranged in series. In this embodiment, four LEDs arranged in series are used as an example for illustration. Since it is the average current per unit time that determines the brightness of the LED, both the working current and the preset current can be understood as the average current. Since the light-emitting module 2 is arranged in series with the first switch unit 4 , the light-emitting time of the light-emitting module 2 can be controlled by controlling the on-time of the first switch unit 4 , thereby controlling the average current of the light-emitting module 2 and adjusting the light-emitting module 2 operating current.
  • the first switch unit 4 in the embodiment of the present application is a voltage-controlled device, such as a transistor, which may be an NMOS transistor; the Vgs (the voltage between the gate and the source) of the first switch unit 4 can be controlled to The on-resistance Rds between the drain and the source of the first switch unit 4 is controlled, that is, the conduction state of the first switch unit 4 is controlled; since the light-emitting module 2 is arranged in series with the first switch unit 4, the size of Rds can be controlled by to control the voltage division of the light-emitting module 2 on the entire circuit, so as to adjust the working current of the light-emitting module 2 .
  • the light-emitting time and voltage division of the light-emitting module 2 can be adjusted by adjusting the conduction time and the degree of conduction of the first switch unit 4, so as to adjust the working current of the light-emitting module 2 to a preset current, so that the light-emitting module
  • the luminous brightness of 2 is kept at the preset luminous brightness, which avoids the problem of current fluctuation and uneven brightness caused by the short circuit of the LED in the light-emitting module 2, which is beneficial to improve the stability of the backlight brightness, and when the backlight constant current control circuit 1 is applied to the display In the device, it is beneficial to improve the display effect.
  • the constant current control module 3 further includes a feedback unit 5 and a sampling unit 6 .
  • the sampling unit 6 is electrically connected to the light-emitting module 2 through the first switch unit 4;
  • the feedback unit 5 is electrically connected to the sampling unit 6 and the first switch unit 4, respectively, for detecting the voltage Vs across the sampling unit 6, and when the sampling unit is detected 6.
  • the sampling unit 6 has a fixed resistance value R 0 , and the light-emitting module 2 , the first switch unit 4 and the sampling unit 6 are connected in series, so the currents flowing through the light-emitting module 2 , the first switch unit 4 and the sampling unit 6 are of the same magnitude; Therefore, the working current of the light emitting module 2 can be obtained according to the voltage Vs across the sampling unit 6 .
  • the feedback unit 5 includes a level shifter Ls, a first PWM controller 7 and a comparator Com.
  • the comparator Com is electrically connected to the sampling unit 6 and the first PWM controller 7 respectively, and is used to detect the voltage Vs at both ends of the sampling unit 6 and compare the voltage Vs at both ends of the sampling unit 6 with the preset voltage Vref; When the voltage Vs at both ends deviates from the preset voltage Vref, it is determined that the operating current of the light-emitting module 2 deviates from the preset current, and a level signal is output to the first PWM controller 7 according to the degree of deviation.
  • the first PWM controller 7 is also electrically connected to the level shifter Ls for outputting a first duty cycle signal to the level shifter Ls according to the level signal.
  • the level shifter Ls is also electrically connected to the first switch unit 4 for adjusting the level of the first duty cycle signal, and adjusting the on-time of the first switch unit 4 through the adjusted first duty cycle signal and continuity.
  • the comparator Com when the working current of the light-emitting module 2 deviates (greater than) the preset current in the positive direction, the comparator Com outputs the first level signal to the first PWM controller 7 , and when the working current of the light-emitting module 2 deviates in the negative direction (less than) ) when the current is preset, the comparator Com outputs a second level signal to the first PWM controller 7; the first PWM controller 7 outputs a different first duty cycle signal according to the first level signal and the second level signal .
  • the level shifter Ls is used for amplifying the first duty cycle signal, that is, increasing the level of the first duty cycle signal.
  • the first switch unit 4 is a first transistor Q1, specifically an NMOS transistor; the sampling unit 6 is a sampling resistor Rs.
  • the drain of the first transistor Q1 is electrically connected to the output terminal of the light emitting module 2 , the source of the first transistor Q1 is grounded through the sampling resistor Rs, and the gate of the first transistor Q1 is electrically connected to the output terminal of the level shifter Ls.
  • the input terminal of the comparator Com is electrically connected to the source of the first transistor Q1 , and the output terminal of the comparator Com is electrically connected to the input terminal of the first PWM controller 7 .
  • the output terminal of the first PWM controller 7 is electrically connected to the input terminal of the level conversion.
  • the input end of the light emitting module 2 is the anode end, and the output end of the light emitting module 2 is the cathode end.
  • the comparator Com includes a non-inverting input terminal (+) and an inverting input terminal (-).
  • the non-inverting input terminal of the comparator Com is electrically connected to the source of the first transistor Q1
  • the inverting input terminal of the comparator Com is connected to the preset voltage Vref, and at this time, the non-inverting input terminal of the comparator Com receives two sampling resistors Rs.
  • the comparator Com Compare the voltage Vs across the sampling unit 6 with the preset voltage Vref, if the voltage Vs across the sampling unit 6 is greater than the preset voltage Vref, the comparator Com outputs a high-level signal to the first PWM controller 7 , if the voltage Vs across the sampling unit 6 is less than the preset voltage Vref, the comparator Com outputs a low-level signal to the first PWM controller 7 .
  • the inverting input terminal of the comparator Com when the inverting input terminal of the comparator Com is electrically connected to the source of the first transistor Q1, the non-inverting input terminal of the comparator Com is connected to the preset voltage Vref, and at this time, the inverting input terminal of the comparator Com receives the sampling The voltage Vs across the resistor Rs; compares the voltage Vs across the sampling unit 6 with the preset voltage Vref, if the voltage Vs across the sampling unit 6 is greater than the preset voltage Vref, the comparator Com outputs a low output to the first PWM controller 7 level signal, if the voltage Vs across the sampling unit 6 is lower than the preset voltage Vref, the comparator Com outputs a high level signal to the first PWM controller 7 .
  • the constant current control module 3 may further include a controller, the controller is electrically connected to the input end of the comparator Com, and is used for outputting the preset voltage Vref to the comparator Com.
  • the constant current control module 3 may further include an adjusting resistor, one end of the adjusting resistor is electrically connected to the controller, and the other end is grounded.
  • the controller can adjust the preset luminous brightness of the light emitting module 2 according to the resistance value of the adjustment resistor. It can be understood that the value of the preset voltage Vref output by the controller is different if the resistance value of the adjustment resistor is different.
  • the setting of the adjusting resistor can make the constant current control module 3 suitable for the light emitting module 2 with different brightness requirements, thereby increasing the application range.
  • the backlight constant current control circuit 1 further includes a boosting module 8 electrically connected to the input end of the light emitting module 2 for providing the preset power supply voltage VDD to the input end of the light emitting module 2 .
  • the boosting module 8 includes a charging and discharging unit 9, a second switching unit 10 and a third switching unit 11; the charging and discharging unit 9 is electrically connected with the second switching unit 10 and the third switching unit 11 respectively, and the third switching unit 11 is connected with the light emitting module
  • the input terminals of 2 are electrically connected.
  • the boosting module 8 is used to adjust the conduction time of the second switch unit 10 and the third switch unit 11 according to the preset luminance; when the second switch unit 10 is turned on, the charging and discharging unit 9 is charged, and when the third switch unit 10 is turned on, the charging and discharging unit 9 is charged. When 11 is turned on, the charging and discharging unit 9 is discharged to output the preset power supply voltage VDD to the input terminal of the light emitting module 2 .
  • the preset power supply voltage VDD in this embodiment is a fixed voltage.
  • the boosting module 8 further includes a driver 12 and a second PWM controller 13; the charging and discharging unit 9 is an inductor Lf, the second switching unit 10 is a second transistor Q2, specifically an NMOS tube, and the third switching unit 11 is a second transistor Q2.
  • the three transistors Q3 are specifically PMOS tubes.
  • the second PWM controller 13 is electrically connected to the input end of the driver 12, and is used for outputting a second duty cycle signal to the driver 12 according to the preset luminous intensity.
  • the input terminal of the driver 12 is electrically connected to the second PWM controller 13, and the output terminal of the driver 12 is electrically connected to the gate of the second transistor Q2 and the gate of the third transistor Q3, respectively, for respectively according to the second duty cycle signal.
  • the turn-on time of the second transistor Q2 and the third transistor Q3 is adjusted.
  • One end of the inductor Lf is connected to the input voltage Vin, and the other end is electrically connected to the drain of the second transistor Q2 and the source of the third transistor Q3 respectively, the source of the second transistor Q2 is grounded, and the drain of the third transistor Q3 is connected to the light-emitting
  • the input end of the module 2 is electrically connected.
  • the boosting module 8 can boost the input voltage Vin to a preset output voltage through the charging process of the inductor Lf, and can output the preset output voltage to the input terminal of the light emitting module 2 through the discharging process of the inductor Lf.
  • the boosting module 8 further includes a first capacitor C1 and a second capacitor C2.
  • One end of the first capacitor C1 is electrically connected to one end of the inductor Lf away from the second transistor Q2, and the other end is grounded to keep the input voltage Vin stable;
  • one end of the second capacitor C2 is electrically connected to the input end of the light-emitting module 2, The other end is grounded to keep the preset output voltage VDD stable.
  • the other input end of the driver 12 is also connected to the enable signal En.
  • the enable signal En When the enable signal En is at a high level, the driver 12 is in a working state, and when the enable signal En is at a low level, the driver 12 is in an off state;
  • the enable signal En may be provided to the driver 12 through gate driving.
  • the working principle of the boosting module 8 is as follows: when the driver 12 is connected to the high-level enable signal En, the boosting module 8 starts to work, and the second PWM controller 13 turns the light-emitting module 2 according to the preset luminance of the light-emitting module 2 .
  • the driver 12 outputs the second duty cycle signal, and the driver 12 controls the second transistor Q2 and the third transistor Q3 to be turned on successively according to the second duty cycle signal.
  • the inductor Lf When the second transistor Q2 is turned on and the third transistor Q3 is turned off, the inductor Lf is charged, the input voltage Vin flows through the inductor Lf, and the current on the inductor Lf increases linearly in a certain proportion; when the second transistor Q2 is turned off and the third transistor Q3 is turned on, the inductor Lf is discharged and flows through the inductor Lf The current of Lf flows to the input terminal of the light emitting module 2 and charges the second capacitor C2, so that the voltage VDD received by the input terminal of the light emitting module 2 is higher than the input voltage Vin. Therefore, by controlling the turn-on time of the second transistor Q2 and the third transistor Q3 to be different, the increase ratio of the input voltage Vin can be controlled to be different, so that different VDD can be provided according to the preset brightness.
  • the embodiment of the present application does not limit the provision of the preset power supply voltage VDD to the input end of the light emitting module 2 in other manners.
  • the constant current control module 3 includes a first switch unit 4 and a sampling unit 6 arranged in series with the light emitting module 2 in sequence, and a first switch unit 4 and a sampling unit 6 respectively connected to the first switch unit 4 and the sampling unit 6 Electrically connected feedback unit 5 .
  • the constant current control module 3 detects the voltage Vs across the sampling unit 6 through the feedback unit 5, thereby indirectly detecting the working current of the light-emitting module 2, and when it is detected that the working current of the light-emitting module 2 deviates from the preset current, the feedback unit 5 adjusts the first
  • the conduction time and conduction degree of the switch unit 4 can adjust the lighting time of the lighting module 2 and the voltage division of the lighting module, so that the working current (average current) of the lighting module 2 can be adjusted, so that the working current of the lighting module 2 is equal to the preset voltage.
  • the luminous brightness of the light-emitting module 2 can be maintained at the preset luminous brightness, which avoids the problem of uneven brightness of the backlight structure caused by the current fluctuation of the light-emitting module 2, and is beneficial to improve the stability of the backlight brightness; when the backlight constant current control When the circuit 1 is applied to a display device, it is beneficial to improve the display effect.
  • an embodiment of the present application further provides a backlight structure 14, and the backlight structure 14 includes a plurality of backlight constant current control circuits provided in the foregoing embodiments.
  • the backlight structure 14 includes at least one backlight sub-region 15, and each backlight sub-region 15 is provided with at least one light-emitting module of a backlight constant current control circuit.
  • the multiple constant current control modules in the multiple backlight constant current control circuits are integrated in the same control chip 16 , and the boost module in the backlight constant current control circuit can also be integrated into the control chip 16 .
  • a light-emitting module and a connecting line between the light-emitting module and the control chip 16 are arranged in the backlight partition 15, and the control chip 16 can be arranged in the frame area or the back of the backlight structure 14 to avoid being arranged in the backlight partition 15, and through a
  • the control chip 16 can control the light emitting modules of multiple partitions, which can effectively simplify the circuit structure of the backlight partition 15, which is beneficial to reduce costs.
  • the first end of the control chip 16 is connected to the input voltage Vin
  • the second end of the control chip 16 is connected to the enable signal En
  • the third end of the control chip 16 is grounded
  • the fourth end of the control chip 16 is connected to a plurality of The output ends of the light emitting modules in the backlight sub-areas 15 are electrically connected
  • the fifth ends of the control chip 16 are respectively electrically connected with the output ends of the light-emitting modules in the plurality of backlight sub-areas 15 .
  • 3a and 3b illustrate by taking four backlight sub-regions 15 as an example, and the four backlight sub-regions 15 are respectively provided with light-emitting modules D1, D2, D3 and D4.
  • the control chip 16 may only be provided with one boosting module, the boosting module
  • the output terminals of the light-emitting modules are respectively electrically connected to the input terminals of the light-emitting modules D1, D2, D3 and D4 to provide the same preset power supply voltage VDD; at this time, the number of boost modules can be reduced, and the power of the enable signal En can be reduced at the same time.
  • the number of input terminals is conducive to simplifying the circuit and saving costs.
  • a boosting module is set in the control chip 16 corresponding to each backlight sub-region 15, so that the input terminals of the light-emitting modules D1, D2, D3 and D4 receive the
  • the VDDs are different, such as VDD1, VDD2, VDD3 and VDD4, and each booster module corresponds to an enable signal En, such as En1, En2, En3 and En4.
  • the constant current control module in the backlight structure 14 can perform constant current control on the light emitting module, so as to avoid the fluctuation of the working current of the light emitting module due to the short circuit of the LEDs from affecting the luminous brightness, so the backlight structure 14 can be applied to the liquid crystal display device. , providing a backlight source with stable brightness for the liquid crystal display panel, which is beneficial to the stability and uniform distribution of the backlight brightness, thereby helping to improve the display effect.
  • the constant current control module and the boosting module in the backlight structure 14 are integrated in one control chip 16, so that the backlight structure 14 can adjust the light-emitting brightness of the light-emitting modules of the plurality of backlight partitions 15 through one control chip 16, which is conducive to simplifying
  • the circuit structure of the backlight partition 15 can reduce the cost.
  • the embodiment of the present application also provides a backlight structure, which is different from the above-mentioned embodiment in that the constant current control module and the boosting module corresponding to each backlight partition are arranged in an independent control chip, that is, one control chip controls one backlight Partitioned lighting modules.

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Abstract

一种背光恒流控制电路（1）和背光结构（14），背光恒流控制电路（1）包括发光模块（2）和恒流控制模块（3）；恒流控制模块（3）包括第一开关单元（4）；恒流控制模块（3）用于在检测到发光模块（2）的工作电流偏离预设电流时，调节第一开关单元（4）的导通时间和导通程度，以调节发光模块（2）的工作电流至预设电流，使发光模块（2）的发光亮度保持为预设发光亮度。

Description

背光恒流控制电路和背光结构
本申请要求于2020年10月16日提交中国国家知识产权局、申请号为202011110366.6、发明名称为“一种背光恒流控制电路和背光结构”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及显示技术领域，尤其涉及显示驱动技术领域，具体涉及一种背光恒流控制电路和背光结构。
 背景技术
随着信息化社会的蓬勃发展，面板产业驱动技术的日益成熟，机遇与挑战也随之而来，由于LCD背光的局限性，如功耗大、对比度低等缺点，迫使背光朝着Local dimming（局部可控制）的方向发展。
随着技术的发展，一种超小工艺结构的Mini LED已实现小批量量产，Mini LED因结构小，可实现更多分区，相比于传统LCD显示技术，Mini LED背光具有更多的背光分区，使电视画质精细度更高、能耗更低、画面更细致，对比度越明显。
现有的Mini LED背光采用有源选址驱动(AM：ActiveMatrix，又称有源寻址、主动寻址、有源驱动等)方案实现的Local Dimming背光，每一分区由多个LED灯串联组成，采用恒压控制方式（即VDD电压固定）驱动每一分区工作，当电路中有一个LED灯故障短路后，分区内的LED灯串的总电阻变小，由于LED灯串两端的电压不变，使得这一分区LED灯串的电流变大，而LED灯对电流极其敏感，该分区的显示亮度将大于其他分区，或大于需求的亮度，导致整个背光亮度不均，极大的影响了显示效果。
 技术问题
本申请提供一种背光恒流控制电路和背光结构，通过对发光模块进行恒流控制可以避免发光模块中的某个器件短路后影响发光模块的电流，有利于使发光模块的电流保持为预设电流，使得发光模块的发光亮度保持为预设发光亮度，从而保证背光亮度稳定以及分布均匀，有利于提高显示效果。
 技术解决方案
本申请提供一种背光恒流控制电路，包括发光模块和恒流控制模块；
所述恒流控制模块包括第一开关单元；所述恒流控制模块用于在检测到所述发光模块的工作电流偏离预设电流时，调节所述第一开关单元的导通时间和导通程度，以调节所述发光模块的工作电流至所述预设电流，使所述发光模块的发光亮度保持为预设发光亮度。
在本申请所提供的背光恒流控制电路中，所述恒流控制模块还包括反馈单元和采样单元；
所述采样单元与所述第一开关单元电连接；
所述反馈单元分别与所述采样单元和所述第一开关单元电连接，用于检测所述采样单元两端的电压，并在检测到所述采样单元两端的电压偏离预设电压时，确定所述发光模块的工作电流偏离所述预设电流，调节所述第一开关单元的导通时间和导通程度，以调节所述发光模块的工作电流至所述预设电流。
在本申请所提供的背光恒流控制电路中，所述反馈单元包括电平转换器、第一PWM控制器和比较器；
所述比较器分别与所述采样单元和所述第一PWM控制器电连接，用于检测所述采样单元两端的电压，并比较所述采样单元两端的电压与所述预设电压的大小；在所述采样单元两端的电压偏离所述预设电压时，确定所述发光模块的工作电流偏离所述预设电流，根据偏离程度向所述第一PWM控制器输出电平信号；
所述第一PWM控制器还与所述电平转换器电连接，用于根据所述电平信号向所述电平转换器输出占空比信号；
所述电平转换器还与所述第一开关单元电连接，用于调节所述占空比信号的电平大小，并通过调节后的所述占空比信号调节所述第一开关单元的导通时间和导通程度。
在本申请所提供的背光恒流控制电路中，所述第一开关单元包括第一晶体管，所述采样单元包括采样电阻；
所述第一晶体管的漏极与所述发光模块的输出端电连接，所述第一晶体管的源极通过所述采样电阻接地，所述第一晶体管的栅极与所述电平转换器的输出端电连接；
所述比较器的输入端与所述第一晶体管的源极电连接，所述比较器的输出端与所述第一PWM控制器的输入端电连接；
所述第一PWM控制器的输出端与所述电平转换的输入端电连接。
在本申请所提供的背光恒流控制电路中，所述发光模块包括多个串联设置的LED。
在本申请所提供的背光恒流控制电路中，所述背光恒流控制电路还包括与所述发光模块的输入端电连接的升压模块；
所述升压模块包括充放电单元、第二开关单元和第三开关单元；所述充放电单元分别与所述第二开关单元和所述第三开关单元电连接；
所述升压模块用于根据所述预设发光亮度调节所述第二开关单元和所述第三开关单元的导通时间；在所述第二开关单元导通时使所述充放电单元充电，且在所述第三开关单元导通时使所述充放电单元放电，以向所述发光模块的输入端输出预设电源电压。
在本申请所提供的背光恒流控制电路中，所述升压模块还包括驱动器和第二PWM控制器；所述充放电单元包括电感，所述第二开关单元包括第二晶体管，所述第三开关单元包括第三晶体管；
所述第二PWM控制器与所述驱动器的输入端电连接；所述驱动器的输入端与所述第二PWM控制器电连接，所述驱动器的输出端分别与所述第二晶体管的栅极和所述第三晶体管的栅极电连接；
所述电感的一端接入输入电压，另一端分别与所述第二晶体管的漏极和所述第三晶体管的源极电连接，所述第二晶体管的源极接地，所述第三晶体管的漏极与所述发光模块的输入端电连接。
在本申请所提供的背光恒流控制电路中，所述升压模块还包括第一电容和第二电容；所述第一电容的一端与所述电感远离所述第二晶体管的一端电连接，另一端接地；所述第二电容的一端与所述发光模块的输入端电连接，另一端接地。
本申请还提供一种背光结构，包括多个上述的背光恒流控制电路；所述背光结构包括至少一个背光分区，每个所述背光分区设有至少一个所述背光恒流控制电路的发光模块。
在本申请所提供的背光结构中，多个所述背光恒流控制电路中的多个所述恒流控制模块集成设置在同一控制芯片中。
在本申请所提供的背光结构中，所述背光恒流控制电路还包括与所述发光模块的输入端电连接的升压模块，所述升压模块也集成设置在所述控制芯片中。
在本申请所提供的背光结构中，所述升压模块包括充放电单元、第二开关单元和第三开关单元；所述充放电单元分别与所述第二开关单元和所述第三开关单元电连接；
所述升压模块用于根据所述预设发光亮度调节所述第二开关单元和所述第三开关单元的导通时间；在所述第二开关单元导通时使所述充放电单元充电，且在所述第三开关单元导通时使所述充放电单元放电，以向所述发光模块的输入端输出预设电源电压。
在本申请所提供的背光结构中，每个所述背光分区对应的所述恒流控制模块设置在独立的控制芯片中。
在本申请所提供的背光结构中，所述恒流控制模块还包括反馈单元和采样单元；
所述采样单元与所述第一开关单元电连接；
所述反馈单元分别与所述采样单元和所述第一开关单元电连接，用于检测所述采样单元两端的电压，并在检测到所述采样单元两端的电压偏离预设电压时，确定所述发光模块的工作电流偏离所述预设电流，调节所述第一开关单元的导通时间和导通程度，以调节所述发光模块的工作电流至所述预设电流。
在本申请所提供的背光结构中，所述反馈单元包括电平转换器、第一PWM控制器和比较器；
所述比较器分别与所述采样单元和所述第一PWM控制器电连接，用于检测所述采样单元两端的电压，并比较所述采样单元两端的电压与所述预设电压的大小；在所述采样单元两端的电压偏离所述预设电压时，确定所述发光模块的工作电流偏离所述预设电流，根据偏离程度向所述第一PWM控制器输出电平信号；
所述第一PWM控制器还与所述电平转换器电连接，用于根据所述电平信号向所述电平转换器输出占空比信号；
所述电平转换器还与所述第一开关单元电连接，用于调节所述占空比信号的电平大小，并通过调节后的所述占空比信号调节所述第一开关单元的导通时间和导通程度。
在本申请所提供的背光结构中，所述第一开关单元包括第一晶体管，所述采样单元包括采样电阻；
所述第一晶体管的漏极与所述发光模块的输出端电连接，所述第一晶体管的源极通过所述采样电阻接地，所述第一晶体管的栅极与所述电平转换器的输出端电连接；
所述比较器的输入端与所述第一晶体管的源极电连接，所述比较器的输出端与所述第一PWM控制器的输入端电连接；
所述第一PWM控制器的输出端与所述电平转换的输入端电连接。
在本申请所提供的背光结构中，所述发光模块包括多个串联设置的LED。
在本申请所提供的背光结构中，所述背光恒流控制电路还包括与所述发光模块的输入端电连接的升压模块；
所述升压模块包括充放电单元、第二开关单元和第三开关单元；所述充放电单元分别与所述第二开关单元和所述第三开关单元电连接；
所述升压模块用于根据所述预设发光亮度调节所述第二开关单元和所述第三开关单元的导通时间；在所述第二开关单元导通时使所述充放电单元充电，且在所述第三开关单元导通时使所述充放电单元放电，以向所述发光模块的输入端输出预设电源电压。
在本申请所提供的背光结构中，所述升压模块还包括驱动器和第二PWM控制器；所述充放电单元包括电感，所述第二开关单元包括第二晶体管，所述第三开关单元包括第三晶体管；
所述第二PWM控制器与所述驱动器的输入端电连接；所述驱动器的输入端与所述第二PWM控制器电连接，所述驱动器的输出端分别与所述第二晶体管的栅极和所述第三晶体管的栅极电连接；
所述电感的一端接入输入电压，另一端分别与所述第二晶体管的漏极和所述第三晶体管的源极电连接，所述第二晶体管的源极接地，所述第三晶体管的漏极与所述发光模块的输入端电连接。
在本申请所提供的背光结构中，所述升压模块还包括第一电容和第二电容；所述第一电容的一端与所述电感远离所述第二晶体管的一端电连接，另一端接地；所述第二电容的一端与所述发光模块的输入端电连接，另一端接地。
 有益效果
本申请提供的背光恒流控制电路和背光结构，恒流控制模块包括与发光模块电连接的第一开关单元；恒流控制模块在检测到发光模块的工作电流偏离预设电流时，可以通过调节第一开关单元的导通时间和导通程度来调节发光模块的发光时间以及发光模块的分压，从而可以调节发光模块的工作电流（平均电流），使得发光模块的工作电流等于预设电流，故发光模块的发光亮度可以保持为预设发光亮度，避免了发光模块因电流波动导致背光结构亮度不均的问题，有利于提高背光亮度的稳定性；当该背光恒流控制电路和背光结构应用到显示装置中时，有利于提高显示效果。
 附图说明
下面结合附图，通过对本申请的具体实施方式详细描述，将使本申请的技术方案及其它有益效果显而易见。
图1为本申请实施例提供的背光恒流控制电路的示意框图。
图2为本申请实施例提供的背光恒流控制电路的电路示意图。
图3a为本申请实施例提供的一种背光结构的示意图。
图3b为本申请实施例提供的另一种背光结构的示意图。
 本发明的实施方式
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述。显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
在本申请的描述中，需要理解的是，术语“中心”、“纵向”、“横向”、“长度”、“宽度”、“厚度”、“上”、“下”、“前”、“后”、“左”、“右”、“竖直”、“水平”、“顶”、“底”、“内”、“外”、“顺时针”、“逆时针”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本申请和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请的限制。此外，术语“第一”、“第二”仅用于描述目的，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”的特征可以明示或者隐含地包括一个或者更多个所述特征。在本申请的描述中，“多个”的含义是两个或两个以上，除非另有明确具体的限定。
在本申请的描述中，需要说明的是，除非另有明确的规定和限定，术语“安装”、“相连”、“连接”应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或一体地连接；可以是机械连接，也可以是电连接或可以相互通讯；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通或两个元件的相互作用关系。对于本领域的普通技术人员而言，可以根据具体情况理解上述术语在本申请中的具体含义。
在本申请中，除非另有明确的规定和限定，第一特征在第二特征之“上”或之“下”可以包括第一和第二特征直接接触，也可以包括第一和第二特征不是直接接触而是通过它们之间的另外的特征接触。而且，第一特征在第二特征“之上”、“上方”和“上面”包括第一特征在第二特征正上方和斜上方，或仅仅表示第一特征水平高度高于第二特征。第一特征在第二特征“之下”、“下方”和“下面”包括第一特征在第二特征正下方和斜下方，或仅仅表示第一特征水平高度小于第二特征。
下文的公开提供了许多不同的实施方式或例子用来实现本申请的不同结构。为了简化本申请的公开，下文中对特定例子的部件和设置进行描述。当然，它们仅仅为示例，并且目的不在于限制本申请。此外，本申请可以在不同例子中重复参考数字和/或参考字母，这种重复是为了简化和清楚的目的，其本身不指示所讨论各种实施方式和/或设置之间的关系。此外，本申请提供了的各种特定的工艺和材料的例子，但是本领域普通技术人员可以意识到其他工艺的应用和/或其他材料的使用。
如图1和图2所示，本申请实施例提供了一种背光恒流控制电路1，背光恒流控制电路1包括发光模块2和恒流控制模块3；其中，恒流控制模块3包括与发光模块2串联设置的第一开关单元4；恒流控制模块3用于在检测到发光模块2的工作电流偏离预设电流时，调节第一开关单元4的导通时间和导通程度，以调节发光模块2的工作电流至预设电流，使发光模块2的发光亮度保持为预设发光亮度。
具体的，本申请实施例中，发光模块2的发光亮度受工作电流的控制；其中，工作电流为发光模块2发光时的实际电流大小，预设电流为发光模块2在预设发光亮度时流过发光模块2的电流大小；因此，预设电流可以根据预设发光亮度获得。
具体的，发光模块2包括多个串联设置的LED，具体可以是多个串联设置的Mini-LED，本实施例中以4个串联设置的LED为例进行示意说明。由于决定LED发光亮度的是单位时间内的平均电流，工作电流和预设电流均可以理解为平均电流。由于发光模块2与第一开关单元4串联设置，可以通过控制第一开关单元4的导通时间来控制发光模块2的发光时间，从而控制发光模块2的平均电流的大小，实现调节发光模块2的工作电流。另外，本申请实施例中的第一开关单元4为压控型器件，例如晶体管，具体可以为NMOS管；可以通过控制第一开关单元4的Vgs（栅极和源极之间的电压）来控制第一开关单元4的漏极和源极间的导通电阻Rds，即控制第一开关单元4的导通状态；由于发光模块2与第一开关单元4串联设置，可以通过控制Rds的大小来控制发光模块2在整个电路上的分压，从而调节发光模块2的工作电流。因此，本申请实施例可以通过调节第一开关单元4的导通时间和导通程度来调节发光模块2的发光时间和分压，从而调节发光模块2的工作电流至预设电流，使发光模块2的发光亮度保持为预设发光亮度，避免了发光模块2中的LED短路导致电流波动以及亮度不均的问题，有利于提高背光亮度的稳定性，且当背光恒流控制电路1应用到显示装置中时，有利于提高显示效果。
恒流控制模块3还包括反馈单元5和采样单元6。采样单元6通过第一开关单元4与发光模块2电连接；反馈单元5分别与采样单元6和第一开关单元4电连接，用于检测采样单元6两端的电压Vs，并在检测到采样单元6两端的电压Vs偏离预设电压Vref时，确定发光模块2的工作电流偏离预设电流，调节第一开关单元4的导通时间和导通程度，以调节发光模块2的工作电流至预设电流。
具体的，采样单元6具有固定阻值R 0，发光模块2、第一开关单元4和采样单元6串联连接，故流过发光模块2、第一开关单元4和采样单元6的电流大小相同；因此，可以根据采样单元6两端的电压Vs获得发光模块2的工作电流。本申请实施例中的预设电压Vref为采样单元6的电流为预设电流时采样单元6两端的电压Vs，即预设电压Vref=预设电流×R 0，因此，可以通过比较采样单元6两端的电压Vs与预设电压Vref的大小来比较发光模块2的工作电流与预设电流的大小。
具体的，反馈单元5包括电平转换器Ls、第一PWM控制器7和比较器Com。
比较器Com分别与采样单元6和第一PWM控制器7电连接，用于检测采样单元6两端的电压Vs，并比较采样单元6两端的电压Vs与预设电压Vref的大小；在采样单元6两端的电压Vs偏离预设电压Vref时，确定发光模块2的工作电流偏离预设电流，根据偏离程度向第一PWM控制器7输出电平信号。第一PWM控制器7还与电平转换器Ls电连接，用于根据电平信号向电平转换器Ls输出第一占空比信号。电平转换器Ls还与第一开关单元4电连接，用于调节第一占空比信号的电平大小，并通过调节后的第一占空比信号调节第一开关单元4的导通时间和导通程度。
具体的，当发光模块2的工作电流正向偏离（大于）预设电流时，比较器Com向第一PWM控制器7输出第一电平信号，当发光模块2的工作电流负向偏离（小于）预设电流时，比较器Com向第一PWM控制器7输出第二电平信号；第一PWM控制器7根据第一电平信号和第二电平信号输出不同的第一占空比信号。
具体的，电平转换器Ls用于放大第一占空比信号，即增大第一占空比信号的电平。
在一实施例中，第一开关单元4为第一晶体管Q1，具体为NMOS管；采样单元6为采样电阻Rs。第一晶体管Q1的漏极与发光模块2的输出端电连接，第一晶体管Q1的源极通过采样电阻Rs接地，第一晶体管Q1的栅极与电平转换器Ls的输出端电连接。比较器Com的输入端与第一晶体管Q1的源极电连接，比较器Com的输出端与第一PWM控制器7的输入端电连接。第一PWM控制器7的输出端与电平转换的输入端电连接。
可以理解的，发光模块2的输入端为阳极端，发光模块2的输出端为阴极端。
具体的，比较器Com包括同相输入端（＋）和反相输入端（－）。当比较器Com的同相输入端与第一晶体管Q1的源极电连接时，比较器Com的反相输入端接入预设电压Vref，此时，比较器Com的同相输入端接收采样电阻Rs两端的电压Vs；比较采样单元6两端的电压Vs与预设电压Vref的大小，若采样单元6两端的电压Vs大于预设电压Vref，则比较器Com向第一PWM控制器7输出高电平信号，若采样单元6两端的电压Vs小于预设电压Vref，则比较器Com向第一PWM控制器7输出低电平信号。当然，当比较器Com的反相输入端与第一晶体管Q1的源极电连接时，比较器Com的同相输入端接入预设电压Vref，此时，比较器Com的反相输入端接收采样电阻Rs两端的电压Vs；比较采样单元6两端的电压Vs与预设电压Vref的大小，若采样单元6两端的电压Vs大于预设电压Vref，则比较器Com向第一PWM控制器7输出低电平信号，若采样单元6两端的电压Vs小于预设电压Vref，则比较器Com向第一PWM控制器7输出高电平信号。
在一实施例中，恒流控制模块3还可以包括一控制器，该控制器与比较器Com的输入端电连接，用于向比较器Com输出预设电压Vref。恒流控制模块3还可以包括一调节电阻，调节电阻的一端与控制器电连接，另一端接地。控制器可以根据调节电阻的阻值大小调整发光模块2的预设发光亮度，可以理解的是，调节电阻的阻值不同，则控制器输出的预设电压Vref的大小不同。该调节电阻的设置可以使恒流控制模块3适用于不同亮度需求的发光模块2，增大应用范围。
具体的，背光恒流控制电路1还包括与发光模块2的输入端电连接的升压模块8，用于向发光模块2的输入端提供预设电源电压VDD。升压模块8包括充放电单元9、第二开关单元10和第三开关单元11；充放电单元9分别与第二开关单元10和第三开关单元11电连接，第三开关单元11与发光模块2的输入端电连接。升压模块8用于根据预设发光亮度调节第二开关单元10和第三开关单元11的导通时间；在第二开关单元10导通时使充放电单元9充电，且在第三开关单元11导通时使充放电单元9放电，以向发光模块2的输入端输出预设电源电压VDD。
需要说明的是，本实施例中的预设电源电压VDD为一固定电压。
具体的，升压模块8还包括驱动器12和第二PWM控制器13；充放电单元9为电感Lf，第二开关单元10为第二晶体管Q2，具体为NMOS管，第三开关单元11为第三晶体管Q3，具体为PMOS管。第二PWM控制器13与驱动器12的输入端电连接，用于根据预设发光亮度向驱动器12输出第二占空比信号。驱动器12的输入端与第二PWM控制器13电连接，驱动器12的输出端分别与第二晶体管Q2的栅极和第三晶体管Q3的栅极电连接，用于根据第二占空比信号分别调节第二晶体管Q2和第三晶体管Q3的导通时间。电感Lf的一端接入输入电压Vin，另一端分别与第二晶体管Q2的漏极和第三晶体管Q3的源极电连接，第二晶体管Q2的源极接地，第三晶体管Q3的漏极与发光模块2的输入端电连接。
具体的，升压模块8通过电感Lf的充电过程可以将输入电压Vin升高为预设输出电压，且通过电感Lf的放电过程可以将预设输出电压向发光模块2的输入端输出。
具体的，升压模块8还包括第一电容C1和第二电容C2。其中，第一电容C1的一端与电感Lf远离第二晶体管Q2的一端电连接，另一端接地，用于使输入电压Vin保持稳定；第二电容C2的一端与发光模块2的输入端电连接，另一端接地，用于使预设输出电压VDD保持稳定。
具体的，驱动器12的另一输入端还接入使能信号En，当使能信号En为高电平时，驱动器12处于工作状态，当使能信号En为低电平时，驱动器12处于关闭状态；可以通过栅极驱动向驱动器12提供使能信号En。
具体的，升压模块8的工作原理为：当驱动器12接入高电平的使能信号En时，升压模块8开始工作，第二PWM控制器13根据发光模块2的预设发光亮度向驱动器12输出第二占空比信号，驱动器12根据第二占空比信号控制第二晶体管Q2和第三晶体管Q3先后导通，当第二晶体管Q2导通且第三晶体管Q3断开时，电感Lf进行充电，输入电压Vin流过电感Lf，且电感Lf上的电流以一定的比例线性增大；当第二晶体管Q2断开且第三晶体管Q3导通时，电感Lf进行放电，流过电感Lf的电流流向发光模块2的输入端并对第二电容C2进行充电，使得发光模块2的输入端接收到的电压VDD高于输入电压Vin。因此，通过控制第二晶体管Q2和第三晶体管Q3的导通时间的不同，可以控制输入电压Vin的增大比例不同，故可以根据预设亮度不同提供不同的VDD。
当然，本申请实施例不限制采用其他方式向发光模块2的输入端提供预设电源电压VDD。
本申请实施例提供的背光恒流控制电路1中，恒流控制模块3包括依次与发光模块2串联设置的第一开关单元4和采样单元6，以及分别与第一开关单元4和采样单元6电连接的反馈单元5。恒流控制模块3通过反馈单元5检测采样单元6两端的电压Vs，从而间接检测发光模块2的工作电流，且在检测到发光模块2的工作电流偏离预设电流时，通过反馈单元5调节第一开关单元4的导通时间和导通程度来调节发光模块2的发光时间以及发光模块的分压，从而可以调节发光模块2的工作电流（平均电流），使得发光模块2的工作电流等于预设电流，故发光模块2的发光亮度可以保持为预设发光亮度，避免了发光模块2因电流波动导致背光结构亮度不均的问题，有利于提高背光亮度的稳定性；当该背光恒流控制电路1应用到显示装置中时，有利于提高显示效果。
如图3a和图3b所示，本申请实施例还提供了一种背光结构14，背光结构14包括多个上述实施例中提供的背光恒流控制电路。背光结构14包括至少一个背光分区15，每个背光分区15设有至少一个背光恒流控制电路的发光模块。
具体的，多个背光恒流控制电路中的多个恒流控制模块集成设置在同一控制芯片16中，且背光恒流控制电路中的升压模块也可以集成设置在该控制芯片16中。此时，背光分区15内设置发光模块以及发光模块与控制芯片16之间的连接线，而控制芯片16可以设置在背光结构14的边框区或背面，避免设置在背光分区15，且通过一颗控制芯片16可以控制多个分区的发光模块，可以有效的的精简背光分区15的电路结构，有利于降低成本。
具体的，控制芯片16的第一端接入输入电压Vin，控制芯片16的第二端接入使能信号En，控制芯片16的第三端接地，控制芯片16的第四端分别与多个背光分区15中的发光模块的输出端电连接，控制芯片16的第五端分别与多个背光分区15中的发光模块的输出端电连接。
图3a和图3b以4个背光分区15为例进行示意，4个背光分区15中分别设置有发光模块D1、D2、D3和D4。如图3a所示，当4个背光分区15的亮度要求一致时，即发光模块D1、D2、D3和D4的预设发光亮度相同，控制芯片16中可以只设置一个升压模块，升压模块的输出端分别与发光模块D1、D2、D3和D4的输入端电连接，用于提供相同的预设电源电压VDD；此时，可以减少升压模块的数量，同时可以减少使能信号En的输入端的数量，有利于简化电路以及节约成本。如图3b所示，当4个背光分区15的亮度要求不同时，控制芯片16中对应每个背光分区15都设置一个升压模块，使得发光模块D1、D2、D3和D4的输入端接收到的VDD不同，例如VDD1、VDD2、VDD3和VDD4，且每个升压模块都对应一个使能信号En，例如En1、En2、En3和En4。
本实施中，背光结构14中的恒流控制模块可以对发光模块进行恒流控制，避免了发光模块因LED短路造成的工作电流波动而影响发光亮度，故背光结构14可以应用在液晶显示装置中，为液晶显示面板提供稳定亮度的背光源，有利于背光亮度稳定以及分布均匀，从而有利于提高显示效果。另外，背光结构14中的恒流控制模块和升压模块集成设置在一个控制芯片16中，使得背光结构14通过一个控制芯片16可以调节多个背光分区15的发光模块的发光亮度，有利于精简背光分区15的电路结构并降低成本。
本申请实施例还提供了一种背光结构，与上述实施例不同的在于，每个背光分区对应的恒流控制模块和升压模块设置在独立的控制芯片中，即一颗控制芯片控制一个背光分区的发光模块。
在上述实施例中，对各个实施例的描述都各有侧重，某个实施例中没有详述的部分，可以参见其他实施例的相关描述。
以上对本申请实施例所提供的一种背光恒流控制电路和背光结构进行了详细介绍，本文中应用了具体个例对本申请的原理及实施方式进行了阐述，以上实施例的说明只是用于帮助理解本申请的技术方案及其核心思想；本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例的技术方案的范围。

Claims (20)

  1. 一种背光恒流控制电路，包括发光模块和恒流控制模块；
    所述恒流控制模块包括第一开关单元；所述恒流控制模块用于在检测到所述发光模块的工作电流偏离预设电流时，调节所述第一开关单元的导通时间和导通程度，以调节所述发光模块的工作电流至所述预设电流，使所述发光模块的发光亮度保持为预设发光亮度。
  2. 如权利要求1所述的背光恒流控制电路，其中，所述恒流控制模块还包括反馈单元和采样单元；
    所述采样单元与所述第一开关单元电连接；
    所述反馈单元分别与所述采样单元和所述第一开关单元电连接，用于检测所述采样单元两端的电压，并在检测到所述采样单元两端的电压偏离预设电压时，确定所述发光模块的工作电流偏离所述预设电流，调节所述第一开关单元的导通时间和导通程度，以调节所述发光模块的工作电流至所述预设电流。
  3. 如权利要求2所述的背光恒流控制电路，其中，所述反馈单元包括电平转换器、第一PWM控制器和比较器；
    所述比较器分别与所述采样单元和所述第一PWM控制器电连接，用于检测所述采样单元两端的电压，并比较所述采样单元两端的电压与所述预设电压的大小；在所述采样单元两端的电压偏离所述预设电压时，确定所述发光模块的工作电流偏离所述预设电流，根据偏离程度向所述第一PWM控制器输出电平信号；
    所述第一PWM控制器还与所述电平转换器电连接，用于根据所述电平信号向所述电平转换器输出占空比信号；
    所述电平转换器还与所述第一开关单元电连接，用于调节所述占空比信号的电平大小，并通过调节后的所述占空比信号调节所述第一开关单元的导通时间和导通程度。
  4. 如权利要求3所述的背光恒流控制电路，其中，所述第一开关单元包括第一晶体管，所述采样单元包括采样电阻；
    所述第一晶体管的漏极与所述发光模块的输出端电连接，所述第一晶体管的源极通过所述采样电阻接地，所述第一晶体管的栅极与所述电平转换器的输出端电连接；
    所述比较器的输入端与所述第一晶体管的源极电连接，所述比较器的输出端与所述第一PWM控制器的输入端电连接；
    所述第一PWM控制器的输出端与所述电平转换的输入端电连接。
  5. 如权利要求1所述的背光恒流控制电路，其中，所述发光模块包括多个串联设置的LED。
  6. 如权利要求1所述的背光恒流控制电路，其中，所述背光恒流控制电路还包括与所述发光模块的输入端电连接的升压模块；
    所述升压模块包括充放电单元、第二开关单元和第三开关单元；所述充放电单元分别与所述第二开关单元和所述第三开关单元电连接；
    所述升压模块用于根据所述预设发光亮度调节所述第二开关单元和所述第三开关单元的导通时间；在所述第二开关单元导通时使所述充放电单元充电，且在所述第三开关单元导通时使所述充放电单元放电，以向所述发光模块的输入端输出预设电源电压。
  7. 如权利要求6所述的背光恒流控制电路，其中，所述升压模块还包括驱动器和第二PWM控制器；所述充放电单元包括电感，所述第二开关单元包括第二晶体管，所述第三开关单元包括第三晶体管；
    所述第二PWM控制器与所述驱动器的输入端电连接；所述驱动器的输入端与所述第二PWM控制器电连接，所述驱动器的输出端分别与所述第二晶体管的栅极和所述第三晶体管的栅极电连接；
    所述电感的一端接入输入电压，另一端分别与所述第二晶体管的漏极和所述第三晶体管的源极电连接，所述第二晶体管的源极接地，所述第三晶体管的漏极与所述发光模块的输入端电连接。
  8. 如权利要求7所述的背光恒流控制电路，其中，所述升压模块还包括第一电容和第二电容；所述第一电容的一端与所述电感远离所述第二晶体管的一端电连接，另一端接地；所述第二电容的一端与所述发光模块的输入端电连接，另一端接地。
  9. 一种背光结构，包括多个如权利要求1所述的背光恒流控制电路；所述背光结构包括至少一个背光分区，每个所述背光分区设有至少一个所述背光恒流控制电路的发光模块。
  10. 如权利要求9所述的背光结构，其中，多个所述背光恒流控制电路中的多个所述恒流控制模块集成设置在同一控制芯片中。
  11. 如权利要求10所述的背光结构，其中，所述背光恒流控制电路还包括与所述发光模块的输入端电连接的升压模块，所述升压模块也集成设置在所述控制芯片中。
  12. 如权利要求11所述的背光结构，其中，所述升压模块包括充放电单元、第二开关单元和第三开关单元；所述充放电单元分别与所述第二开关单元和所述第三开关单元电连接；
    所述升压模块用于根据所述预设发光亮度调节所述第二开关单元和所述第三开关单元的导通时间；在所述第二开关单元导通时使所述充放电单元充电，且在所述第三开关单元导通时使所述充放电单元放电，以向所述发光模块的输入端输出预设电源电压。
  13. 如权利要求9所述的背光结构，其中，每个所述背光分区对应的所述恒流控制模块设置在独立的控制芯片中。
  14. 如权利要求9所述的背光结构，其中，所述恒流控制模块还包括反馈单元和采样单元；
    所述采样单元与所述第一开关单元电连接；
    所述反馈单元分别与所述采样单元和所述第一开关单元电连接，用于检测所述采样单元两端的电压，并在检测到所述采样单元两端的电压偏离预设电压时，确定所述发光模块的工作电流偏离所述预设电流，调节所述第一开关单元的导通时间和导通程度，以调节所述发光模块的工作电流至所述预设电流。
  15. 如权利要求14所述的背光结构，其中，所述反馈单元包括电平转换器、第一PWM控制器和比较器；
    所述比较器分别与所述采样单元和所述第一PWM控制器电连接，用于检测所述采样单元两端的电压，并比较所述采样单元两端的电压与所述预设电压的大小；在所述采样单元两端的电压偏离所述预设电压时，确定所述发光模块的工作电流偏离所述预设电流，根据偏离程度向所述第一PWM控制器输出电平信号；
    所述第一PWM控制器还与所述电平转换器电连接，用于根据所述电平信号向所述电平转换器输出占空比信号；
    所述电平转换器还与所述第一开关单元电连接，用于调节所述占空比信号的电平大小，并通过调节后的所述占空比信号调节所述第一开关单元的导通时间和导通程度。
  16. 如权利要求15所述的背光结构，其中，所述第一开关单元包括第一晶体管，所述采样单元包括采样电阻；
    所述第一晶体管的漏极与所述发光模块的输出端电连接，所述第一晶体管的源极通过所述采样电阻接地，所述第一晶体管的栅极与所述电平转换器的输出端电连接；
    所述比较器的输入端与所述第一晶体管的源极电连接，所述比较器的输出端与所述第一PWM控制器的输入端电连接；
    所述第一PWM控制器的输出端与所述电平转换的输入端电连接。
  17. 如权利要求9所述的背光结构，其中，所述发光模块包括多个串联设置的LED。
  18. 如权利要求9所述的背光结构，其中，所述背光恒流控制电路还包括与所述发光模块的输入端电连接的升压模块；
    所述升压模块包括充放电单元、第二开关单元和第三开关单元；所述充放电单元分别与所述第二开关单元和所述第三开关单元电连接；
    所述升压模块用于根据所述预设发光亮度调节所述第二开关单元和所述第三开关单元的导通时间；在所述第二开关单元导通时使所述充放电单元充电，且在所述第三开关单元导通时使所述充放电单元放电，以向所述发光模块的输入端输出预设电源电压。
  19. 如权利要求18所述的背光结构，其中，所述升压模块还包括驱动器和第二PWM控制器；所述充放电单元包括电感，所述第二开关单元包括第二晶体管，所述第三开关单元包括第三晶体管；
    所述第二PWM控制器与所述驱动器的输入端电连接；所述驱动器的输入端与所述第二PWM控制器电连接，所述驱动器的输出端分别与所述第二晶体管的栅极和所述第三晶体管的栅极电连接；
    所述电感的一端接入输入电压，另一端分别与所述第二晶体管的漏极和所述第三晶体管的源极电连接，所述第二晶体管的源极接地，所述第三晶体管的漏极与所述发光模块的输入端电连接。
  20. 如权利要求19所述的背光结构，其中，所述升压模块还包括第一电容和第二电容；所述第一电容的一端与所述电感远离所述第二晶体管的一端电连接，另一端接地；所述第二电容的一端与所述发光模块的输入端电连接，另一端接地。
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