LED backlight driving chip, driving circuit, module and brightness control method

Abstract

The present disclosure provides an LED backlight driving chip, a driving circuit, a module and a brightness control method. The LED backlight driving chip comprises a power supply circuit and a voltage detection circuit. An input end of the power supply circuit and an anode of an LED lamp bead are connected to an external power line. The power supply circuit receives an external power voltage transmitted by the external power line, converts the external power voltage into a first internal power voltage, and supplies power to the voltage detection circuit based on the first internal power voltage. The voltage detection circuit detects each voltage of the external power voltage and the cathode voltage of a plurality of LED lamp beads in sequence, obtains an anode detection voltage of the LED lamp bead and a cathode detection voltage of the plurality of LED lamp beads, and sends a plurality of detection voltages to a host computer, so that the host computer determines the temperature of each LED lamp bead based on the plurality of detection voltages. The LED backlight driving chip can simplify the wiring of the LED backlight module, and can accurately detect the actual temperature of the LED lamp bead.

Description

Technical Field

[0001] The embodiments disclosed herein relate to the field of LED backlight driving technology, and more particularly to LED backlight driving chips, driving circuits, modules, and brightness control methods. Background Technology

[0002] In display panels, sub-millimeter light-emitting diode (Mini LED) backlight modules typically employ two power supplies. One power supply provides a fixed voltage and powers the LED backlight driver chip to drive the LED chips for dimming. The other power supply powers the LED chips and can be dynamically adjusted in real time. Both power supplies are generated by direct current (DC) to DC converters. The light intensity of LED chips varies with temperature. Existing solutions infer the temperature distribution of the LED backlight panel by detecting the internal temperature of the chip, thereby adjusting the driving current of the LED chips.

[0003] However, using two power supplies would consume more wiring resources for the LED backlight module, making the wiring of the LED backlight module complex. If the temperature distribution of the LED backlight board is estimated by using the chip's own junction temperature, the actual temperature of the LED chips cannot be accurately detected because there is a difference between the chip's own junction temperature and the ambient temperature. Summary of the Invention

[0004] This disclosure provides an LED backlight driver chip, driver circuit, module, and brightness control method, which can simplify the wiring of the LED backlight module and accurately detect the actual temperature of the LED beads.

[0005] In a first aspect, this disclosure provides an LED backlight driver chip, including a power supply circuit and a voltage detection circuit. The input terminal of the power supply circuit, the first input terminal of the voltage detection circuit, and the anodes of a plurality of LED beads are connected to an external power supply line. The output terminal of the power supply circuit is connected to the power supply terminal of the voltage detection circuit. The plurality of second input terminals of the voltage detection circuit are connected one-to-one with the cathodes of the plurality of LED beads. The output terminal of the voltage detection circuit is connected to a host computer.

[0006] The power supply circuit is configured to receive an external power supply voltage transmitted from the external power line, convert the external power supply voltage into a first internal power supply voltage, and supply power to the voltage detection circuit based on the first internal power supply voltage.

[0007] The voltage detection circuit is configured to receive multiple input voltages, sequentially detect each of the multiple input voltages to obtain multiple detection voltages, and send the multiple detection voltages to the host computer so that the host computer can determine the temperature of each LED bead based on the multiple detection voltages. The multiple input voltages include the external power supply voltage and the cathode voltages of the multiple LED beads, and the multiple detection voltages include the anode detection voltage and the cathode detection voltage of the multiple LED beads.

[0008] In some embodiments of this disclosure, the power supply circuit includes a first linear regulator and a voltage converter. The LED backlight driver chip also includes a power supply voltage input pin. The input terminal of the voltage converter and the input terminal of the first linear regulator are connected to the external power line through the power supply voltage input pin. The output terminal of the first linear regulator is connected to the power supply terminal of the voltage converter, and the output terminal of the voltage converter is connected to the power supply terminal of the voltage detection circuit.

[0009] The first linear regulator is configured to convert the external power supply voltage into a second internal power supply voltage and provide the second internal power supply voltage to the voltage converter to power the voltage converter.

[0010] The voltage converter is configured to step down the external power supply voltage to obtain the first internal power supply voltage.

[0011] In some embodiments of this disclosure, the voltage converter includes a transformer ratio selection circuit, a switched capacitor array, and a voltage conversion control circuit. The input terminals of the transformer ratio selection circuit and the switched capacitor array are connected to the power supply voltage input pin. The first input terminal of the voltage conversion control circuit is connected to the output terminal of the transformer ratio selection circuit, the second input terminal of the voltage conversion control circuit is connected to the output terminal of the switched capacitor array, and the output terminal of the voltage conversion control circuit is connected to the control terminal of the switched capacitor array.

[0012] The transformer ratio selection circuit is configured to determine the transformer ratio of the voltage converter based on the external power supply voltage.

[0013] The voltage conversion control circuit is configured to control the capacitors in the switched capacitor array to charge and discharge based on the transformation ratio and the first internal power supply voltage, so as to control the switched capacitor array to step down the external power supply voltage to the first internal power supply voltage.

[0014] In some embodiments of this disclosure, the voltage converter is a switched capacitor converter, and the power supply circuit further includes a second linear regulator, the output terminal of the voltage converter being connected to the output terminal of the power supply circuit through the second linear regulator.

[0015] In some embodiments of this disclosure, the LED backlight driver chip further includes a power supply voltage output pin, the output terminal of the voltage converter is connected to the first plate of an external filter capacitor through the power supply voltage output pin, and the second plate of the external filter capacitor is connected to the ground potential line.

[0016] In some embodiments of this disclosure, the voltage detection circuit includes an analog-to-digital converter and a time-division control circuit. The LED backlight driver chip further includes a power supply voltage input pin and multiple LED cathode voltage input pins. The first input terminal of the analog-to-digital converter is connected to the external power supply line through the power supply voltage input pin. Each second input terminal of the analog-to-digital converter is connected to the cathode of an LED through an LED cathode voltage input pin. The output terminal of the time-division control circuit is connected to the control terminal of the analog-to-digital converter, and the output terminal of the analog-to-digital converter is connected to the host computer.

[0017] The time-division control circuit is configured to provide a gating signal to the analog-to-digital converter.

[0018] The analog-to-digital converter is configured to select a target voltage input pin from a plurality of voltage input pins based on the gating signal, and convert the target input voltage received by the target voltage input pin into a target detection voltage; wherein the plurality of voltage input pins includes the power supply voltage input pin and the plurality of LED cathode voltage input pins.

[0019] In some embodiments of this disclosure, the LED backlight driver chip further includes an interface circuit and a data output pin. The output terminal of the time-division control circuit is connected to the control terminal of the analog-to-digital converter through the interface circuit, and the output terminal of the analog-to-digital converter is connected to the data output pin through the interface circuit to send the target detection voltage to the host computer.

[0020] In a second aspect, this disclosure provides an LED backlight driving circuit, including a plurality of LED backlight driving chips provided in the first aspect, each LED backlight driving chip being connected to a plurality of LED beads within the same LED backlight zone.

[0021] Thirdly, this disclosure provides an LED backlight module, including an LED backlight board and an LED backlight driving circuit provided in the second aspect. The LED backlight board includes multiple LED backlight zones, and each LED backlight zone is provided with multiple LED beads.

[0022] Fourthly, this disclosure provides an LED backlight brightness control method, applied to an LED backlight brightness control system, the LED backlight brightness control system including a host computer and the LED backlight driver chip provided in the first aspect, the method comprising: The system receives the plurality of detection voltages sent by the LED backlight driver chip; determines the temperature of the plurality of LED beads based on the plurality of detection voltages; and adjusts the driving current of the corresponding LED bead based on the temperature of each LED bead to make the brightness of LED beads with the same brightness requirement consistent.

[0023] In some embodiments of this disclosure, determining the temperature of the plurality of LED beads based on the plurality of detected voltages includes: Based on the anode detection voltage of the LED beads and the cathode detection voltage of the plurality of LED beads, the actual driving voltage of the plurality of LED beads is determined, wherein the plurality of detection voltages include the anode detection voltage of the LED beads and the cathode detection voltage of the plurality of LED beads; based on the actual driving voltage of each LED bead and the voltage-temperature characteristic curve of the corresponding LED bead, the temperature of the corresponding LED bead is determined.

[0024] In some embodiments of this disclosure, adjusting the driving current of the corresponding LED based on the temperature of each LED to ensure that the brightness of LEDs with the same brightness requirement is consistent includes: Based on the temperature of each LED, the actual luminous intensity of the corresponding LED is determined; based on the actual luminous intensity and the target luminous intensity of each LED, the luminous intensity adjustment amount of the corresponding LED is determined; wherein, the target luminous intensity is used to characterize the brightness requirement; based on the luminous intensity adjustment amount of each LED, the driving current adjustment amount of the corresponding LED is determined; based on the driving current adjustment amount of each LED, the driving current of the corresponding LED is adjusted.

[0025] The technical solution disclosed herein provides an LED backlight driver chip, including a power supply circuit and a voltage detection circuit. By connecting the input terminal of the power supply circuit and the anode of the LED chip to an external power supply line, the power supply circuit receives the external power supply voltage transmitted by the external power supply line, converts the external power supply voltage into a first internal power supply voltage, and supplies power to the voltage detection circuit based on the first internal power supply voltage. Power can be supplied to the LED chip and the LED backlight driver chip based on the same external power supply line, which can save the wiring resources of the LED backlight module and simplify the wiring of the LED backlight module.

[0026] In addition, the voltage detection circuit sequentially detects each of the external power supply voltage and the cathode voltage of multiple LED beads to obtain the anode detection voltage and cathode detection voltage of the LED beads. The multiple detection voltages are then sent to the host computer so that the host computer can determine the temperature of each LED bead based on the multiple detection voltages. The actual temperature of the LED bead can be accurately detected based on the actual driving voltage of the LED bead. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. It should be understood that the drawings described below only relate to some embodiments of this disclosure and are not intended to limit this disclosure, wherein: Figure 1 A schematic diagram of the structure of an LED backlight module provided by the prior art.

[0028] Figure 2 A schematic diagram of another LED backlight module provided by the prior art.

[0029] Figure 3 This is a schematic diagram of the structure of an LED backlight module provided in an embodiment of the present disclosure.

[0030] Figure 4 This is a schematic diagram of the structure of an LED backlight driver chip provided in an embodiment of this disclosure.

[0031] Figure 5 This is a schematic diagram of a power supply circuit provided in an embodiment of the present disclosure.

[0032] Figure 6 This is a schematic diagram of another LED backlight driver chip provided in an embodiment of this disclosure.

[0033] Figure 7 This is a schematic diagram of another power supply circuit provided in an embodiment of the present disclosure.

[0034] Figure 8 This is a schematic diagram of another LED backlight module provided in an embodiment of the present disclosure.

[0035] Figure 9 This is a schematic diagram of the structure of a voltage converter provided in an embodiment of the present disclosure.

[0036] Figure 10 This is a flowchart illustrating an LED backlight brightness control method provided in an embodiment of the present disclosure.

[0037] Figure 11 This is a schematic diagram of the normalized luminous intensity of a red LED bead as a function of temperature, provided in an embodiment of this disclosure. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are also within the scope of protection of this disclosure.

[0039] In this disclosure, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of the phrase "embodiment" in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this disclosure can be combined with other embodiments.

[0040] Furthermore, the terms "first," "second," etc., in the specification, claims, or the accompanying drawings are used to distinguish different objects rather than to describe a specific order, and may explicitly or implicitly include one or more of the features.

[0041] In the description of this disclosure, unless otherwise stated, "multiple" and "at least two" mean two or more (including two), and similarly, "multiple groups" and "at least two groups" mean two or more (including two groups).

[0042] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0043] Figure 1 A schematic diagram of the structure of an LED backlight module provided for the prior art, such as... Figure 1 As shown, the LED backlight module 100 includes an LED backlight board 110 and an LED backlight driving circuit 120. The LED backlight board 110 includes multiple LED backlight zones, and each LED backlight zone contains multiple LED beads (LED_1 to LED_N). The LED backlight driving circuit 120 includes multiple LED backlight driving chips (Chip_1 to Chip_M), and each LED backlight driving chip is connected to multiple LED beads (LED_1 to LED_N) within the same LED backlight zone. Here, M and N are both integers greater than 1.

[0044] For example, such as Figure 1As shown, each LED backlight driver chip includes two power supply pins and N LED pins. Both power supply pins are connected to the first power supply line to receive the first power supply voltage VDD1. The N LED pins are connected one-to-one with the cathodes of all LED beads (LED_1 to LED_N) in the corresponding LED backlight zone. The anodes of all LED beads (LED_1 to LED_N) are connected to the second power supply line to receive the second power supply voltage VDD2.

[0045] The first power supply voltage VDD1 is the operating voltage of the LED backlight driver chip, which is a fixed voltage generated by the DC-DC converter and is usually set to less than 5V to drive the LED beads for dimming. The second power supply voltage VDD2 is the anode voltage of the LED beads, which is an adjustable voltage generated by the DC-DC converter. Its voltage range is usually set to several volts to tens of volts and can be flexibly configured according to different models of LED beads. While ensuring the driving current of the LED beads, the second power supply voltage VDD2 is kept as low as possible to reduce the voltage on the LED pins.

[0046] Therefore, the LED backlight driver chip and the LED backlight board need to be powered independently, which will result in occupying more wiring resources of the LED backlight module and making the wiring of the LED backlight module more complicated.

[0047] To save on wiring in LED backlight modules, existing technologies have proposed LED backlight module 200, such as... Figure 2 As shown, Figure 2 A schematic diagram of another LED backlight module provided in the prior art includes an LED backlight board 210 and an LED backlight driving circuit 220. The LED backlight board 210 includes multiple LED backlight zones, each containing multiple LED beads (LED_1 to LED_N). The LED backlight driving circuit 220 includes multiple LED backlight driving chips (Chip_1 to Chip_M), each connected to multiple LED beads (LED_1 to LED_N) within the same LED backlight zone.

[0048] For example, such as Figure 2 As shown, each LED backlight driver chip includes two power supply pins and N LED pins. The N LED pins are connected one-to-one with the cathodes of all LED beads (LED_1 to LED_N) within the corresponding LED backlight zone. The anodes of all LED beads (LED_1 to LED_N) are connected to the second power supply line to receive the second power supply voltage VDD2. The two power supply pins are internally connected within the LED backlight driver chip.

[0049] Multiple LED backlight driver chips connected in series are connected to the first power line to receive the first power supply voltage VDD1, thus achieving series power supply. For example, ... Figure 2 As shown, one power pin of LED backlight driver chip Chip_1 is connected to the first power line, another power pin of LED backlight driver chip Chip_1 is connected to one power pin of LED backlight driver chip Chip_2, and another power pin of LED backlight driver chip Chip_2 is connected to one power pin of LED backlight driver chip Chip_3.

[0050] However, the overcurrent capacity inside the LED backlight driver chip is limited and does not support too many series connections. Usually, only two or three levels can be connected in series. Therefore, the power supply of the LED backlight driver chip and the LED backlight board still occupies a lot of the wiring resources of the LED backlight module.

[0051] In view of this, the present disclosure provides an LED backlight module, including an LED backlight board and a plurality of LED backlight driver chips. The LED backlight driver chip includes a power supply circuit and a voltage detection circuit. The LED backlight board includes a plurality of LED beads. The input terminal of the power supply circuit and the anode of the LED beads are connected to an external power supply line. The power supply circuit receives the external power supply voltage transmitted by the external power supply line, converts the external power supply voltage into a first internal power supply voltage, and supplies power to the voltage detection circuit based on the first internal power supply voltage. In this way, power can be supplied to the LED beads and the LED backlight driver chips based on the same external power supply line, which can save the wiring resources of the LED backlight module and simplify the wiring of the LED backlight module.

[0052] The LED backlight module provided in this disclosure will be described in detail below with reference to several specific embodiments.

[0053] Figure 3 This is a schematic diagram of the structure of an LED backlight module provided in an embodiment of the present disclosure, as shown below. Figure 3 As shown, the LED backlight module 300 includes an LED backlight board 310 and an LED backlight driving circuit 320. The LED backlight board 310 includes multiple LED backlight zones, and each LED backlight zone is equipped with multiple LED beads (LED_1 to LED_N). The LED backlight driving circuit 320 includes multiple LED backlight driving chips 400, and each LED backlight driving chip 400 is connected to the multiple LED beads (LED_1 to LED_N) in the same LED backlight zone.

[0054] For example, Figure 4 This is a schematic diagram of the structure of an LED backlight driver chip provided in an embodiment of this disclosure, combined with... Figure 3 and Figure 4As shown, the LED backlight driver chip 400 includes a power supply circuit 410 and a voltage detection circuit 420. The input terminal of the power supply circuit 410, the first input terminal of the voltage detection circuit 420, and the anodes of multiple LED beads (LED_1 to LED_N) are connected to an external power supply line. The output terminal of the power supply circuit 410 is connected to the power supply terminal of the voltage detection circuit 420. The multiple second input terminals of the voltage detection circuit 420 are connected one-to-one with the cathodes of the multiple LED beads (LED_1 to LED_N). The output terminal of the voltage detection circuit 420 is connected to a host computer.

[0055] The power supply circuit 410 is configured to receive an external power supply voltage VLED+ transmitted from an external power supply line, convert the external power supply voltage VLED+ into a first internal power supply voltage VDD, and provide power to the voltage detection circuit 420 based on the first internal power supply voltage VDD.

[0056] The voltage detection circuit 420 is configured to receive multiple input voltages, sequentially detect each of the multiple input voltages to obtain multiple detection voltages, and send the multiple detection voltages to a host computer so that the host computer can determine the temperature of each LED bead based on the multiple detection voltages. The multiple input voltages include the external power supply voltage VLED+ and the cathode voltages of the multiple LED beads (VLED-_1 to VLED-_N), and the multiple detection voltages include the anode detection voltage Vdet_0 of the LED beads and the cathode detection voltages of the multiple LED beads (Vdet_1 to Vdet_N).

[0057] See also Figure 3 and Figure 4 The LED backlight driver chip 400 also includes a power supply voltage input pin Vled. The input terminal of the power supply circuit 410 is connected to an external power supply line through the power supply voltage input pin Vled to receive the external power supply voltage VLED+.

[0058] For example, Figure 5 This is a schematic diagram of a power supply circuit provided in an embodiment of the present disclosure, such as... Figure 5 As shown, the power supply circuit 410 includes a first linear regulator 411 and a voltage converter 412. The input terminal of the voltage converter 412 and the input terminal of the first linear regulator 411 are connected to an external power supply line through the power supply voltage input pin Vled. The output terminal of the first linear regulator 411 is connected to the power supply terminal of the voltage converter 412, and the output terminal of the voltage converter 412 is connected to the power supply terminal of the voltage detection circuit 420.

[0059] The first linear regulator 411 can be a low dropout regulator (LDO). The first linear regulator 411 receives the external power supply voltage VLED+ transmitted from the external power line through the power supply voltage input pin Vled, performs step-down regulation on the external power supply voltage VLED+ to convert the external power supply voltage VLED+ into a second internal power supply voltage VDD_PRE, and provides the second internal power supply voltage VDD_PRE to the voltage converter 412 to supply power to the voltage converter 412.

[0060] The voltage converter 412 can be a step-down voltage converter, such as a step-down switched capacitor converter. The voltage converter 412 includes a power stage circuit and a control stage circuit. The control stage circuit is powered by the second internal power supply voltage VDD_PRE. The power stage circuit receives the external power supply voltage VLED+ and is controlled by the control stage circuit to step down the external power supply voltage VLED+ to obtain the first internal power supply voltage VDD. The first internal power supply voltage VDD is then provided to the voltage detection circuit 420 to supply power to the voltage detection circuit 420.

[0061] In summary, the LED backlight driver chip 400 and the LED chips are connected to the same external power line and powered by the same external power supply voltage VLED+, thus saving wiring resources in the LED backlight module and simplifying the wiring of the LED backlight module.

[0062] For example, Figure 6 This is a schematic diagram of another LED backlight driver chip provided in an embodiment of this disclosure, combined with... Figure 3 , Figure 4 and Figure 6 As shown, the LED backlight driver chip 400 also includes multiple LED cathode voltage input pins (led1 to ledN). The voltage detection circuit 420 includes an analog-to-digital converter (ADC) and a time-division control circuit 421. The first input terminal of the ADC is connected to an external power supply line through the power supply voltage input pin Vled. Each second input terminal of the ADC is connected to the cathode of an LED through an LED cathode voltage input pin. The output terminal of the time-division control circuit 421 is connected to the control terminal of the ADC. The output terminal of the ADC is connected to a host computer.

[0063] For example, such as Figure 6 As shown, the output terminal of the voltage converter 410 is connected to the power supply terminal of the analog-to-digital converter (ADC) and the power supply terminal of the time-division control circuit 421. The voltage converter 410 provides a first internal power supply voltage VDD to the ADC and the time-division control circuit 421 to supply power to them.

[0064] An analog-to-digital converter (ADC) has one first input terminal and N second input terminals. During the operation of the ADC, only one input terminal is selected at any given time, allowing the ADC to convert the input voltage received at the selected input terminal to obtain the detection voltage. For example, if the first input terminal is selected, the ADC detects the external power supply voltage VLED+ to obtain the anode detection voltage Vdet_0 of the LED. If the i-th second input terminal is selected, the ADC detects the cathode voltage VLED-_i of the i-th LED to obtain the cathode detection voltage Vdet_i of the i-th LED, where 1 ≤ i ≤ N.

[0065] The time-division control circuit 421 can provide a gating signal to the analog-to-digital converter (ADC) to indicate the currently selected input terminal, i.e., the currently selected voltage input pin. Based on the gating signal, the ADC selects a target voltage input pin from multiple voltage input pins and converts the target input voltage received by the target voltage input pin into a target detection voltage to detect multiple input voltages in a time-division manner (external power supply voltage VLED+ and the cathode voltages of the LED beads VLED-_1 to VLED-_N). The multiple voltage input pins include the power supply voltage input pin Vled and multiple LED cathode voltage input pins (led1 to ledN).

[0066] After receiving multiple detection voltages (the anode detection voltage Vdet_0 and the cathode detection voltages Vdet_1 to Vdet_N of the LED beads), the host computer determines the actual driving voltage VLED_i of the i-th LED bead based on the anode detection voltage Vdet_0 and the cathode detection voltage Vdet-_i of the i-th LED bead. Since the relationship between the driving voltage and temperature of an LED bead can be described by a voltage-temperature characteristic curve, the actual driving voltage VLED of the LED bead can be converted based on this curve to obtain the accurate actual temperature of the LED bead.

[0067] In this embodiment of the disclosure, by connecting the input terminal of the power supply circuit 410 and the anode of the LED bead to an external power line, the power supply circuit receives the external power supply voltage VLED+ transmitted by the external power line, converts the external power supply voltage VLED+ into a first internal power supply voltage VDD, and supplies power to the voltage detection circuit 420 based on the first internal power supply voltage VDD. Power can be supplied to the LED bead and the LED backlight driver chip based on the same external power line, which can save the wiring resources of the LED backlight module and simplify the wiring of the LED backlight module.

[0068] In addition, the voltage detection circuit 420 sequentially detects each of the external power supply voltage VLED+ and the cathode voltages (VLED-_1 to VLED-_N) of the LED beads to obtain the anode detection voltage Vdet_0 of the LED beads and the cathode detection voltages (Vdet_1 to Vdet_N) of multiple LED beads. The multiple detection voltages are then sent to the host computer so that the host computer can determine the temperature of each LED bead based on the multiple detection voltages. The actual temperature of the LED beads can be accurately detected based on the actual driving voltage of the LED beads.

[0069] In some embodiments, Figure 7 A schematic diagram of another power supply circuit provided in an embodiment of this disclosure is shown below. Figure 7 As shown, the voltage converter 412 is a step-down switched capacitor converter, and the power supply circuit 410 also includes a second linear regulator 413. The output terminal of the voltage converter 412 is connected to the output terminal of the power supply circuit 410 through the second linear regulator 413.

[0070] For example, since the output voltage of the switched capacitor converter has a large voltage ripple, the first internal power supply voltage VDD output by the voltage converter 412 has a large voltage ripple. The first internal power supply voltage VDD can be regulated by the second linear regulator 413 to obtain a stable third internal power supply voltage VDD_REG, and the third internal power supply voltage VDD_REG is provided to the voltage detection circuit 420 to supply power to the voltage detection circuit 420.

[0071] In some embodiments, Figure 8 This is a schematic diagram of another LED backlight module provided in an embodiment of the present disclosure, as shown below. Figure 8 As shown, the LED backlight driver chip 400 also includes a power supply voltage output pin Vdd, and the LED backlight driver circuit 320 also includes multiple off-chip filter capacitors C, the number of which is the same as the number of off-chip filter capacitors C in the LED backlight driver chip 400.

[0072] Combination Figure 5 , Figure 7 and Figure 8 As shown, the output terminal of the voltage converter 412 is connected to the first plate of the external filter capacitor C through the power supply voltage output pin Vdd, and the second plate of the external filter capacitor C is connected to the ground potential line to filter the first internal power supply VDD voltage output by the voltage converter 412.

[0073] In some embodiments, Figure 9 This is a schematic diagram of the structure of a voltage converter provided in an embodiment of the present disclosure, as shown below. Figure 9As shown, the voltage converter 412 includes a turns ratio selection circuit 4121, a switched capacitor array 4122, and a voltage conversion control circuit 4123. The input terminals of the turns ratio selection circuit 4121 and the switched capacitor array 4122 are connected to the power supply voltage input pin Vled. The first input terminal of the voltage conversion control circuit 4123 is connected to the output terminal of the turns ratio selection circuit 4121, the second input terminal of the voltage conversion control circuit 4123 is connected to the output terminal of the switched capacitor array 4122, and the output terminal of the voltage conversion control circuit 4123 is connected to the control terminal of the switched capacitor array 4122.

[0074] The transformer ratio selection circuit 4121 is configured to determine the transformer ratio of the voltage converter 412 based on the external power supply voltage VLED+.

[0075] The voltage conversion control circuit 4123 is configured to control the capacitors in the switched capacitor array 4122 to charge and discharge based on the transformation ratio and the first internal power supply voltage VDD, so as to control the switched capacitor array 4122 to step down the external power supply voltage VLED+ to the first internal power supply voltage VDD.

[0076] For example, the external power supply voltage VLED+ is flexibly configured based on the type of LED beads, while the operating voltage of the voltage detection circuit 420 is a fixed voltage. Therefore, for different external power supply voltages VLED+, firstly, the transformer ratio selection circuit 4121 needs to determine the transformer ratio that matches the current external power supply voltage VLED+ based on the operating voltage of the voltage detection circuit 420.

[0077] The switched capacitor array 4122 includes multiple switching transistors and at least one capacitor. The voltage conversion control circuit 4123 can receive the transformation ratio output by the transformation ratio selection circuit 4121 and determine the operating timing of each switching transistor based on the transformation ratio to control the on / off state of each switching transistor. During this process, each capacitor charges and discharges to transfer charge, thereby obtaining the first internal power supply voltage VDD. The voltage conversion control circuit 4123 can also receive the first internal power supply voltage VDD to monitor the load state of the voltage converter 412 and adjust the operating timing of each switching transistor based on changes in the first internal power supply voltage VDD to ensure that the first internal power supply voltage VDD reaches a stable value.

[0078] In some embodiments, combined with Figure 3 , Figure 6 and Figure 8 As shown, the LED backlight driver chip 400 also includes an interface circuit 430 and a data output pin DOUT. The output of the time-division control circuit 421 is connected to the control terminal of the analog-to-digital converter (ADC) through the interface circuit 430. The output of the ADC is connected to the data output pin DOUT through the interface circuit 430 to send the target detection voltage to the host computer.

[0079] For example, such as Figure 3 and Figure 8 As shown, the LED backlight driver chip 400 also includes a data input pin DIN. In all the LED backlight driver chips 400 in the LED backlight driver circuit 320, the data output pin DOUT of the previous LED backlight driver chip 400 of any two adjacent LED backlight driver chips 400 is connected to the data input pin DIN of the next LED backlight driver chip 400 to ensure that the detection voltage of all LED beads in the LED backlight board can be transmitted to the host computer.

[0080] like Figure 3 and Figure 8 As shown, the LED backlight driver chip 400 also includes two grounding pins gnd, both of which are connected to the ground potential line to ground GND through the ground potential line.

[0081] This disclosure also provides an LED backlight brightness control system, including a host computer and an LED backlight driver chip 400 provided in any of the above embodiments, which has the functional modules and beneficial effects of the LED backlight driver chip 400, which will not be described in detail here.

[0082] This disclosure also provides an LED backlight brightness control method, which is applied to the above-mentioned LED backlight brightness control system and is specifically executed by a host computer.

[0083] Figure 10 This is a flowchart illustrating an LED backlight brightness control method provided in an embodiment of the present disclosure, as shown below. Figure 10 As shown, the specific steps of the LED backlight brightness control method include: S101 receives multiple detection voltages sent by the LED backlight driver chip.

[0084] S102 determines the temperature of multiple LED beads based on multiple detection voltages.

[0085] For example, firstly, based on the anode detection voltage (Vdet_0) of the LED and the cathode detection voltages (Vdet_1 to Vdet_N) of multiple LEDs, the actual bias voltage of the PN junction of the multiple LEDs, i.e. the actual driving voltage (VLED_1 to VLED_N), is determined.

[0086] For example, based on the anode detection voltage Vdet_0 of the LED bead and the cathode detection voltage Vdet-_i of the i-th LED bead, the actual driving voltage VLED_i of the i-th LED bead is determined as Vdet_0 - Vdet-_i.

[0087] Secondly, based on the actual driving voltage of each LED bead and the voltage-temperature characteristic curve of the corresponding LED bead, the temperature of the corresponding LED bead is determined.

[0088] For example, different types of LED beads have different voltage-temperature characteristic curves. After obtaining the actual driving voltages (VLED_1 to VLED_N) of multiple LED beads, for each LED bead: based on the corresponding voltage-temperature characteristic curve, the actual driving voltage is converted into temperature, thereby obtaining the actual temperature of the LED bead.

[0089] Compared to existing technologies that estimate the temperature distribution of LED backlight boards by measuring the junction temperature of the chip itself, the technology provided in this disclosure can obtain the accurate actual temperature of the LED chips by detecting the actual driving voltage of the LED chips.

[0090] S103, based on the temperature of each LED bead, adjusts the driving current of the corresponding LED bead to make the brightness of LED beads with the same brightness requirement consistent.

[0091] For example, RGB Mini LEDs are quite sensitive to temperature, especially red LEDs. Under the same driving current, the light intensity of the LED will vary significantly under different temperature conditions. Figure 11 As shown, Figure 11 This is a schematic diagram illustrating the normalized luminous intensity of a red LED bead as a function of temperature, provided in an embodiment of this disclosure. For LED beads with the same brightness requirement, their actual brightness is not consistent under different temperature conditions. Therefore, it is necessary to compensate the driving current of the LED bead to compensate for the luminous intensity shift caused by temperature, so that its actual brightness remains consistent.

[0092] A specific description of one possible implementation of S103 is as follows: First, based on the temperature of each LED, the actual luminous intensity of the corresponding LED is determined. Then, based on the actual luminous intensity of each LED and the target luminous intensity used to characterize the brightness requirement, the luminous intensity adjustment amount of the corresponding LED is determined. Subsequently, based on the luminous intensity adjustment amount of each LED, the driving current adjustment amount of the corresponding LED is determined. Finally, based on the driving current adjustment amount of each LED, the driving current of the corresponding LED is adjusted, a corresponding driving current command is generated, and the driving current command is sent to the corresponding LED backlight driver chip.

[0093] After receiving the drive current command, the LED backlight driver chip adjusts the drive current of the corresponding LED beads based on the drive current command. This can accurately compensate for the temperature drift of light intensity, so that the brightness adjustment of LED beads with the same brightness requirements is consistent, thereby improving the consistency of LED bead light intensity at different temperatures.

[0094] In this embodiment of the disclosure, multiple detection voltages sent by the LED backlight driver chip are received, and the temperatures of multiple LED beads are determined based on the multiple detection voltages. Based on the temperature of each LED bead, the driving current of the corresponding LED bead is adjusted to make the brightness of LED beads with the same brightness requirement consistent. This can accurately compensate for the temperature drift of light intensity, thereby improving the consistency of light intensity of LED beads at different temperatures.

[0095] Unless otherwise expressly indicated by the context, the singular form of words used herein and in the appended claims includes the plural form, and vice versa. Thus, when referring to the singular, the plural form of the corresponding term is generally included. Similarly, the terms “comprising” and “including” are to be interpreted as including rather than exclusively. Likewise, the terms “including” and “or” should be interpreted as including unless such interpretation is expressly prohibited herein. Where the term “example” is used herein, the “example” is merely exemplary and illustrative, and should not be considered exclusive or extensive.

[0096] Several embodiments of this disclosure have been described in detail above. However, it is obvious that those skilled in the art can make various modifications and variations to the embodiments of this disclosure without departing from the spirit and scope of this disclosure. The scope of protection of this disclosure is defined by the appended claims.

Claims

1. An LED backlight driver chip, characterized in that, Includes power supply circuit and voltage detection circuit; The input terminal of the power supply circuit, the first input terminal of the voltage detection circuit, and the anodes of the multiple LED beads are connected to an external power supply line. The output terminal of the power supply circuit is connected to the power supply terminal of the voltage detection circuit. The multiple second input terminals of the voltage detection circuit are connected one-to-one with the cathodes of the multiple LED beads. The output terminal of the voltage detection circuit is connected to a host computer. The power supply circuit is configured to receive an external power supply voltage transmitted by the external power line, convert the external power supply voltage into a first internal power supply voltage, and supply power to the voltage detection circuit based on the first internal power supply voltage. The voltage detection circuit is configured to receive multiple input voltages, sequentially detect each of the multiple input voltages to obtain multiple detection voltages, and send the multiple detection voltages to the host computer so that the host computer can determine the temperature of each LED bead based on the multiple detection voltages; wherein, the multiple input voltages include the external power supply voltage and the cathode voltage of the multiple LED beads, and the multiple detection voltages include the anode detection voltage and the cathode detection voltage of the multiple LED beads.

2. The LED backlight driver chip according to claim 1, characterized in that, The power supply circuit includes a first linear regulator and a voltage converter, and the LED backlight driver chip also includes a power supply voltage input pin. The input terminal of the voltage converter and the input terminal of the first linear regulator are connected to the external power supply line through the power supply voltage input pin. The output terminal of the first linear regulator is connected to the power supply terminal of the voltage converter, and the output terminal of the voltage converter is connected to the power supply terminal of the voltage detection circuit. The first linear regulator is configured to convert the external power supply voltage into a second internal power supply voltage and provide the second internal power supply voltage to the voltage converter to power the voltage converter; The voltage converter is configured to step down the external power supply voltage to obtain the first internal power supply voltage.

3. The LED backlight driver chip according to claim 2, characterized in that, The voltage converter includes a turns ratio selection circuit, a switched capacitor array, and a voltage conversion control circuit. The input terminal of the transformer ratio selection circuit and the input terminal of the switched capacitor array are connected to the power supply voltage input pin. The first input terminal of the voltage conversion control circuit is connected to the output terminal of the transformer ratio selection circuit. The second input terminal of the voltage conversion control circuit is connected to the output terminal of the switched capacitor array. The output terminal of the voltage conversion control circuit is connected to the control terminal of the switched capacitor array. The transformer ratio selection circuit is configured to determine the transformer ratio of the voltage converter based on the external power supply voltage. The voltage conversion control circuit is configured to control the capacitors in the switched capacitor array to charge and discharge based on the transformation ratio and the first internal power supply voltage, so as to control the switched capacitor array to step down the external power supply voltage to the first internal power supply voltage.

4. The LED backlight driver chip according to claim 2, characterized in that, The voltage converter is a switched capacitor converter, and the power supply circuit further includes a second linear regulator. The output terminal of the voltage converter is connected to the output terminal of the power supply circuit through the second linear regulator.

5. The LED backlight driver chip according to any one of claims 2 to 4, characterized in that, The LED backlight driver chip also includes a power supply voltage output pin. The output terminal of the voltage converter is connected to the first plate of an external filter capacitor through the power supply voltage output pin, and the second plate of the external filter capacitor is connected to the ground potential line.

6. The LED backlight driver chip according to claim 1, characterized in that, The voltage detection circuit includes an analog-to-digital converter and a time-division control circuit, and the LED backlight driver chip also includes a power supply voltage input pin and multiple LED cathode voltage input pins. The first input terminal of the analog-to-digital converter is connected to the external power supply line through the power supply voltage input pin. Each second input terminal of the analog-to-digital converter is connected to the cathode of an LED through an LED cathode voltage input pin. The output terminal of the time-sharing control circuit is connected to the control terminal of the analog-to-digital converter. The output terminal of the analog-to-digital converter is connected to the host computer. The time-division control circuit is configured to provide a gating signal to the analog-to-digital converter; The analog-to-digital converter is configured to select a target voltage input pin from a plurality of voltage input pins based on the gating signal, and convert the target input voltage received by the target voltage input pin into a target detection voltage; wherein the plurality of voltage input pins includes the power supply voltage input pin and the plurality of LED cathode voltage input pins.

7. The LED backlight driver chip according to claim 6, characterized in that, The LED backlight driver chip also includes an interface circuit and data output pins; The output of the time-division control circuit is connected to the control terminal of the analog-to-digital converter through the interface circuit, and the output of the analog-to-digital converter is connected to the data output pin through the interface circuit to send the target detection voltage to the host computer.

8. An LED backlight driving circuit, characterized in that, It includes multiple LED backlight driver chips as described in any one of claims 1 to 7, each LED backlight driver chip being connected to multiple LED beads within the same LED backlight zone.

9. An LED backlight module, characterized in that, It includes an LED backlight panel and the LED backlight driving circuit as described in claim 8. The LED backlight panel includes multiple LED backlight zones, and each LED backlight zone is provided with multiple LED beads.

10. A method for controlling the brightness of an LED backlight, characterized in that, An application is made in an LED backlight brightness control system, the LED backlight brightness control system comprising a host computer and an LED backlight driver chip as described in any one of claims 1 to 7, the method comprising: Receive the plurality of detection voltages sent by the LED backlight driver chip; The temperature of the multiple LED beads is determined based on the multiple detected voltages; Based on the temperature of each LED bead, the driving current of the corresponding LED bead is adjusted to ensure that the brightness of LED beads with the same brightness requirement is consistent.

11. The method according to claim 10, characterized in that, Determining the temperature of the plurality of LED beads based on the plurality of detected voltages includes: Based on the anode detection voltage of the LED beads and the cathode detection voltage of the plurality of LED beads, the actual driving voltage of the plurality of LED beads is determined, wherein the plurality of detection voltages include the anode detection voltage of the LED beads and the cathode detection voltage of the plurality of LED beads; The temperature of the corresponding LED is determined based on the actual driving voltage of each LED and the voltage-temperature characteristic curve of the corresponding LED.

12. The method according to claim 10, characterized in that, The step of adjusting the driving current of the corresponding LED based on the temperature of each LED to ensure that the brightness of LEDs with the same brightness requirement is consistent includes: Based on the temperature of each LED bead, the actual light intensity of the corresponding LED bead is determined; Based on the actual light intensity and target light intensity of each LED, the light intensity adjustment amount of the corresponding LED is determined; wherein, the target light intensity is used to characterize the brightness requirement; Based on the light intensity adjustment amount of each LED, the driving current adjustment amount of the corresponding LED is determined; Based on the driving current adjustment amount of each LED bead, adjust the driving current of the corresponding LED bead.

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