Backlight driving method and backlight driving system

Abstract

The application discloses a backlight driving method and a backlight driving system. The backlight driving method comprises the following steps: arranging temperature sampling elements at different positions in an LED array; obtaining ambient temperatures of different LED sub-zones according to temperature sampling signals; and adjusting driving signals of the different LED sub-zones according to the ambient temperatures, so as to reduce color deviation of the LED array. The application effectively reduces color deviation of the LED array caused by uneven temperature distribution through distributed temperature sampling and temperature compensation for sub-zones, and improves display quality.

Description

Technical Field

[0001] This invention relates to the field of backlight control technology, and more specifically, to a backlight driving method and a backlight driving system. Background Technology

[0002] With the development of display technology, mini-LED backlighting has become the mainstream backlighting solution for high-end display devices due to its advantages such as high contrast, high dynamic range, and local dimming. In a mini-LED backlighting system, the LED array is divided into a large number of independently controllable zones. By adjusting the brightness of each zone, fine local dimming is achieved, thereby improving the contrast and sense of depth of the image.

[0003] However, during operation, the junction temperature of mini-LED chips changes with the driving current and emission time. Both the emission wavelength and luminous efficiency of LEDs are temperature-sensitive: as the junction temperature increases, the peak wavelength of the LED shifts, and the brightness decreases. For RGB tri-color LEDs, different colors are sensitive to temperature differently, causing a shift in the white light color coordinates with temperature changes, resulting in a color cast perceptible to the naked eye. When the temperature distribution in different zones of the LED array is uneven, the degree of color cast varies between zones, further leading to regional color differences across the entire screen, severely impacting display quality.

[0004] Existing compensation schemes for LED color shift problems have the following main shortcomings:

[0005] (1) Unified compensation for the whole board without zoning: Some solutions only set one or a few temperature detection points on the backlight board and apply a uniform compensation amount to all LED zones based on the average temperature of the whole board. However, in reality, due to the different display content and luminous brightness of different zones, there are significant differences in the junction temperature of LEDs in each zone. Unified compensation for the whole board cannot eliminate the color deviation differences between zones.

[0006] (2) Only ambient temperature is detected, without considering the power temperature rise: Most existing temperature compensation schemes only collect the ambient temperature or substrate temperature near the LED, without considering the power temperature rise caused by the LED's own heat generation. In fact, the junction temperature of the LED is equal to the ambient temperature plus the temperature rise caused by its own power dissipation. Using only the ambient temperature as the basis for compensation has a large error, especially when the brightness is high.

[0007] (3) Unreasonable arrangement of temperature sampling points: Some schemes place the temperature detection element inside the driver chip or close to the LED beads, which is easily affected by the heat generated by the power device itself, resulting in the measured temperature not being able to truly reflect the ambient temperature of the LED, thus affecting the compensation accuracy.

[0008] Therefore, there is an urgent need for a backlight driving solution that can achieve high-precision temperature detection and color shift compensation for each zone of mini-LED while keeping costs under control. Summary of the Invention

[0009] In view of this, the present invention provides a backlight driving scheme for achieving high-precision temperature detection and color shift compensation.

[0010] In a first aspect, the present invention provides a backlight driving method for driving an LED array, characterized in that it includes:

[0011] Temperature sampling elements are placed at different positions in the LED array to obtain temperature sampling signals;

[0012] The ambient temperature of different LED zones is obtained based on the temperature sampling signal.

[0013] The drive signals for different LED zones are adjusted based on the ambient temperature to reduce the color shift of the LED array.

[0014] Preferably, the ambient temperature of the LED partition is obtained based on the temperature sampling signal of at least one of the temperature sampling elements adjacent to the target LED partition.

[0015] Preferably, each temperature sampling element is marked with a position according to its physical position in the LED array, so that each temperature sampling element has a corresponding position coordinate; according to the physical position of the target LED partition in the LED array, a temperature sampling element at the corresponding position is selected, and the ambient temperature of the target LED partition is obtained according to its sampling signal.

[0016] Preferably, the temperature sampling elements are evenly distributed in the LED array and are disposed on the light bars of the LED array. The temperature sampling elements are located between adjacent LED partitions and are not physically in contact with the driver chip and the LED partitions.

[0017] Preferably, for an LED partition located in a boundary region, the temperature sampling signal of the temperature sampling element that is closest to the LED partition and located on the boundary is selected as the ambient temperature of the LED partition.

[0018] Preferably, for LED partitions not located in the boundary area, multiple temperature sampling elements closest to the LED partition are selected with the location coordinates of the LED partition as the center. The ambient temperature of the LED partition is calculated by weighting the temperature sampling signals of each temperature sampling element and the distance between the LED partition and each temperature sampling element.

[0019] Preferably, the power temperature rise of each LED partition is calculated based on the real-time power of each LED partition, and the power temperature rise is superimposed on the ambient temperature corresponding to the LED partition to obtain the core temperature of the LED partition. The drive signal of the LED partition is adjusted based on the core temperature.

[0020] Preferably, the power temperature rise of each LED zone is obtained by multiplying the average power of the LED zone by the thermal resistance of the LED beads in the LED zone.

[0021] Preferably, the average power of the LED partition is obtained by multiplying the duty cycle and peak value of the current flowing through the LED partition with the LED voltage drop of the LED partition.

[0022] Preferably, the main control unit in the backlight driving system determines the compensation amount corresponding to the ambient temperature or core temperature according to a preset temperature-duty cycle compensation table or temperature-brightness compensation curve, generates an adjustment signal accordingly, and sends it to the corresponding driving chip. The driving chip generates the driving signal according to the adjustment signal.

[0023] Preferably, the main control unit in the backlight driving system updates the driving information corresponding to the ambient temperature or core temperature according to a preset temperature-duty cycle table or temperature-brightness curve, and sends the driving information to the corresponding driving chip, which then generates the driving signal based on the driving information.

[0024] Preferably, the driving chip includes a temperature detection circuit, a communication circuit, and a driving signal generation circuit. The temperature detection circuit receives the temperature sampling signal and transmits it to the main control unit through the communication circuit. The main control unit obtains a corresponding adjustment signal based on the temperature sampling signal. The adjustment signal is transmitted to the driving signal generation circuit through the communication circuit, and the driving signal is adjusted by the driving signal generation circuit.

[0025] Preferably, each of the driving chips corresponds to at least one temperature sampling element.

[0026] Preferably, the temperature sampling element is sampled once in each frame period to obtain the ambient temperature of each LED partition corresponding to each frame.

[0027] In a second aspect, the present invention provides a backlight driving system for driving an LED array, characterized in that it comprises:

[0028] Multiple temperature sampling elements are distributed at different positions in the backlight driving system to acquire multiple temperature sampling signals corresponding to different positions;

[0029] Multiple driver chips are connected to the main control unit and report the multiple temperature sampling signals.

[0030] The main control unit obtains the ambient temperature of different LED zones based on the multiple temperature sampling signals, and adjusts the driving signals of different LED zones based on at least the ambient temperature, thereby reducing the color shift of the LED array.

[0031] Preferably, the main control unit obtains the ambient temperature of the LED partition based on the temperature sampling signal of at least one temperature sampling element adjacent to the target LED partition.

[0032] Preferably, the main control unit marks the position of each temperature sampling element according to the physical position of each temperature sampling element in the LED array, so that each temperature sampling element has a corresponding position coordinate; according to the physical position of the target LED partition in the LED array, the temperature sampling element at the corresponding position is selected, and the ambient temperature of the target LED partition is obtained according to its sampling signal.

[0033] Preferably, the temperature sampling elements are evenly distributed in the LED array and are disposed on the light bars of the LED array. The temperature sampling elements are located between adjacent LED partitions and do not contact the driver chip or the LED partitions.

[0034] Preferably, for an LED partition located in a boundary region, the temperature sampling signal of the temperature sampling element that is closest to the LED partition and located on the boundary is selected as the ambient temperature of the LED partition.

[0035] Preferably, for LED partitions not located in the boundary area, multiple temperature sampling elements closest to the LED partition are selected with the location coordinates of the LED partition as the center. The ambient temperature of the LED partition is calculated by weighting the temperature sampling signals of each temperature sampling element and the distance between the LED partition and each temperature sampling element.

[0036] Preferably, the main control unit also calculates the power temperature rise of each LED partition based on the real-time power of each LED partition, adds the power temperature rise to the ambient temperature corresponding to the LED partition to obtain the core temperature of the LED partition, and adjusts the drive signal of the LED partition based on the core temperature.

[0037] Preferably, the main control unit includes:

[0038] The ambient temperature module is used to calculate the ambient temperature corresponding to each LED zone based on the temperature sampling signals and locations of each temperature sampling element.

[0039] The power temperature rise module is used to obtain the average power of the LED zone based on the product of the duty cycle and peak value of the current of each LED zone and the LED voltage drop of the LED zone, and multiply the average power by the thermal resistance of the LED beads in the LED zone to obtain the power temperature rise of the LED zone.

[0040] The core temperature module is used to superimpose the ambient temperature and the power temperature rise to obtain the core temperature.

[0041] Preferably, the main control unit further includes a compensation module, which is used to obtain the compensated drive information by looking up a table according to the ambient temperature or core temperature, and send the drive information to the corresponding drive chip, wherein the drive chip generates the drive signal according to the drive information.

[0042] Preferably, each of the driving chips corresponds to at least one of the temperature sampling elements, and the driving chip is electrically coupled to the corresponding temperature sampling element through its temperature detection pin to collect the ambient temperature at the location of the temperature sampling element.

[0043] Preferably, each of the driving chips is connected to a temperature sampling element, which is attached to the area of ​​the light strip driven by the driving chip and is arranged adjacent to the LED partitions in the same area.

[0044] Preferably, each of the driving chips is connected to a plurality of temperature sampling elements, and each temperature sampling element is attached to a different position of the light strip driven by the driving chip.

[0045] Preferably, the temperature detection module uses the frame period of the backlight driving system as the sampling period, and performs temperature sampling once on the temperature sampling element in each frame period to obtain the temperature sampling value corresponding to each frame.

[0046] Preferably, the driver chip sequentially acquires the temperature sampling signals of each temperature sampling element in a time-division sampling manner.

[0047] Preferably, the system further includes a channel selection module, which is coupled between the temperature detection circuit and multiple temperature sampling elements. The control logic of the driver chip controls the channel selection module to select different temperature detection channels in different time periods, so that only one temperature sampling element is connected to the temperature detection circuit in a given time period.

[0048] Preferably, the driving chip performs sampling once for each of the temperature sampling elements connected to it within one frame period to obtain the temperature sampling value of each temperature sampling element corresponding to each frame.

[0049] This invention discloses a backlight driving method and a backlight driving system. The backlight driving method includes: placing temperature sampling elements at different positions in an LED array; obtaining the ambient temperature of different LED zones based on temperature sampling signals; and adjusting the driving signals of different LED zones based on at least the ambient temperature, thereby reducing the color shift of the LED array. This invention effectively reduces the color shift caused by uneven temperature distribution in the LED array through distributed temperature sampling and zone-by-zone temperature compensation, thus improving display quality. Attached Figure Description

[0050] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0051] Figure 1 This is a schematic diagram of the backlight driving system according to the first embodiment of the present invention;

[0052] Figure 2 This is a schematic diagram of the backlight driving system according to the second embodiment of the present invention;

[0053] Figure 3 This is a schematic flowchart of the backlight driving method of the present invention. Detailed Implementation

[0054] The present invention is described below based on embodiments, but the invention is not limited to these embodiments. In the detailed description of the invention below, certain specific details are described in detail. Those skilled in the art will fully understand the invention even without these details. To avoid obscuring the essence of the invention, well-known methods, processes, flows, elements, and circuits are not described in detail.

[0055] Furthermore, those skilled in the art should understand that the accompanying drawings provided herein are for illustrative purposes only and are not necessarily drawn to scale.

[0056] Furthermore, it should be understood that in the following description, "circuit" refers to a conductive loop consisting of at least one element or sub-circuit connected by electrical or electromagnetic connections. When an element or circuit is said to be "connected" to another element or "connected" between two nodes, it can be directly coupled or connected to another element, or there may be intermediate elements. The connection between elements can be physical, logical, or a combination thereof. Conversely, when an element is said to be "directly coupled to" or "directly connected" to another element, it means that there are no intermediate elements between them.

[0057] Unless the context explicitly requires it, the words "comprising," "including," and similar terms throughout the specification and claims should be interpreted as encompassing rather than being exclusive or exhaustive; that is, meaning "including but not limited to."

[0058] In the description of this invention, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0059] Figure 1 A schematic diagram of the backlight driving system structure according to a first embodiment of the present invention is shown. Figure 1 As shown, the backlight driving system includes: an LED array, a main control unit (MCU), multiple driver chips 20, and multiple temperature sampling elements 30 (e.g., NTC thermistors) distributed in the LED array. The multiple temperature sampling elements 30 are distributed at different positions in the backlight driving system to acquire multiple temperature sampling signals corresponding to different positions.

[0060] Figure 1 A block diagram of the internal structure of the driver chip 20 is also shown. (For example...) Figure 1 As shown, the driver chip 20 internally includes a temperature detection circuit 21, a communication circuit 22, and a drive signal generation circuit 23. The temperature detection circuit 21 samples the temperature sampling signal generated by the temperature sampling element 30 through a temperature detection pin, converts the temperature sampling signal into digital temperature information, and stores it in the temperature register inside the driver chip 20. The main control unit (MCU) reads the temperature registers of each driver chip 20 through the communication circuit 22 to obtain the temperature data of each sampling point. The MCU obtains a corresponding adjustment signal based on the temperature sampling signal, and the adjustment signal is transmitted to the drive signal generation circuit 23 through the communication circuit 22. The drive signal generation circuit 23 adjusts the drive signal according to the adjustment signal.

[0061] The temperature detection circuit 21 is integrated inside the driver chip 20. Each driver chip 20 is connected to an external temperature sampling element 30 via its temperature detection pin. One end of the temperature sampling element 30 is connected to the temperature detection pin of the driver chip 20, and the other end is grounded. It should be noted that, due to the inconvenience of drawing diagrams, Figure 1The diagram only shows the driver chip 20 in the first row of light strips connected to an external temperature sampling element 30 via its temperature detection pin. In reality, each driver chip 20 is connected to an external temperature sampling element 30 via its temperature detection pin. It should be noted that in one embodiment, this temperature detection pin can be a dedicated temperature detection pin; in another embodiment, this temperature detection pin can reuse the driver pin of the driver chip 20, which can be achieved by configuring the pin selection function of the driver chip 20.

[0062] The backlight driving system also includes an FPC connector, which is located in the middle or edge area of ​​the light strip. The communication interface of the driver chip 20 is connected to the FPC connector through wiring on the light strip. The FPC connector is connected to the system control board where the main control unit MCU is located via an FPC cable, thereby realizing data interaction between each driver chip 20 and the main control unit MCU. Each driver chip 20 reports a temperature sampling signal to the main control unit MCU through the FPC interface. The temperature sampling signal includes digital temperature information stored in the temperature register of each driver chip 20. The main control unit MCU sends adjusted driving information or compensation signals to each driver chip 20 through the FPC interface.

[0063] The LED array is divided into multiple LED zones 10, with each zone arranged in rows and columns. Each LED zone contains at least one LED bead; in this embodiment, we will use one LED bead per LED zone as an example. Temperature sampling elements 30 are disposed on the LED strips of the LED array. The layout of the temperature sampling elements 30 follows these principles: (1) The temperature sampling elements 30 are evenly distributed in the LED array to cover the temperature distribution area of ​​the entire backlight system as much as possible; (2) The temperature sampling elements 30 are located between adjacent LED zones 10 and are not physically in contact with the driver chip 20 or the LED zone 10. Figure 1 Taking a single LED strip as an example, the strip has three driver chips 20, each connected to an external temperature sampling element 30. The three temperature sampling elements 30 are distributed at different positions on the strip. The temperature sampling elements 30 are not attached to the driver chips 20 or the LED beads to avoid interference from the driver chip's own heat and the LED's power heat, thus ensuring that the collected temperature more accurately reflects the ambient temperature of the LED.

[0064] In a preferred embodiment, after obtaining the temperature data of each sampling point, the main control unit MCU calculates the ambient temperature of each LED zone based on the physical location of each temperature sampling element 30 in the LED array and its temperature sampling signal using a bilinear interpolation algorithm.

[0065] like Figure 1 As shown, the LED array is divided into m columns × n rows, for example, 32 columns × 6 rows. Taking the center point of the bottom left LED partition as the origin, the center coordinates of each LED partition are represented as follows: x-coordinate is 0, 1, 2, …, m-1; y-coordinate is 0, 1, 2, …, n-1. For example, the coordinates of the 32 LED partitions in the first row are (0, 0) to (31, 0); the coordinates of the 32 LED partitions in the second row are (0, 1) to (31, 1); and so on.

[0066] There are i × j temperature sampling points (usually i ≤ m, j ≤ n), and the temperature value of each sampling point is represented as S(i, j). The position coordinates of each sampling point are determined according to its actual physical location. For example, Figure 1 There are 6 × 6 = 36 temperature sampling points set up. The location of each temperature sampling point is the location of each temperature sampling element 30, and the coordinates of each temperature sampling point are determined according to the actual physical location of the temperature sampling element.

[0067] refer to Figure 1 In one embodiment, assuming that each temperature sampling element 30 is located near the driver chip 20 and there are no LED beads between the driver chip 20 and the temperature sampling element 30, the coordinates of the six temperature sampling points in the first row are (1.5, 0), (6.5, 0), (12.5, 0), (18.5, 0), (24.5, 0), and (29.5, 0); the coordinates of the six temperature sampling points in the second row are (1.5, 1), (6.5, 1), (12.5, 1), (18.5, 1), (24.5, 1), and (29.5, 1); and so on.

[0068] In another embodiment, each temperature sampling element 30 is positioned two LED partitions apart from the driver chip 20, and the driver chips 20 and temperature sampling elements 30 in the two left and right LED strips of each row are symmetrically arranged. Figure 1 The positions of the driver chip 20 and temperature sampling element 30 in the bottom row of the LED strip are shown in the diagram. The coordinates of the six temperature sampling points in the first row are (3.5, 0), (8.5, 0), (14.5, 0), (16.5, 0), (22.5, 0), and (27.5, 0); the coordinates of the six temperature sampling points in the second row are (3.5, 1), (8.5, 1), (14.5, 1), (16.5, 1), (22.5, 1), and (27.5, 1); and so on.

[0069] For a target LED partition (m, n), its ambient temperature Q(m, n) is obtained by weighting the temperature values ​​of its nearest surrounding temperature sampling points according to distance. Specifically, for LED partitions located in the boundary region, boundary interpolation is used. The specific calculation method is as follows:

[0070] Here, we take the example where each temperature sampling element 30 is located at a position two LED partitions apart from the driver chip 20. Specifically, the coordinates of the six temperature sampling points in the first row are (3.5, 0), (8.5, 0), (14.5, 0), (16.5, 0), (22.5, 0), and (27.5, 0); the coordinates of the six temperature sampling points in the second row are (3.5, 1), (8.5, 1), (14.5, 1), (16.5, 1), (22.5, 1), and (27.5, 1); and so on.

[0071] For LED partitions in the boundary region, the temperature sampling signal of the temperature sampling element closest to the LED partition and located on the boundary is selected as the ambient temperature Q(m, n) of the LED partition. In this embodiment of the invention, for partitions located in the left boundary region (m < 5): Q(m, n) = S(0, j), where j = n, that is, the ambient temperature of the leftmost 5 LED partitions in each row is the temperature value S(0, j) of the first temperature sampling point in each row; for partitions located in the right boundary region (m > 27): Q(m, n) = S(5, j), where j = n, the ambient temperature of the rightmost 5 LED partitions in each row is the temperature value S(5, j) of the last temperature sampling point in each row. It should be noted that 5 and 27 are not fixed, and in different implementations, they need to be determined according to the actual location of the temperature sampling points in the boundary region.

[0072] For LED zones within the internal area: Using the location coordinates of the LED zone as the center, select multiple temperature sampling elements that are closest to the LED zone. Calculate the ambient temperature Q(m, n) of the LED zone by weighting the temperature sampling signals of each element and the distance between the LED zone and each element.

[0073] For partitions where 5 ≤ m ≤ 9:

[0074] Q(m, n) = S(0, j) + (m - 3.5) × (S(1, j) - S(0, j)) / 5, where j = n;

[0075] For partitions where 10 ≤ m ≤ 15:

[0076] Q(m, n) = S(1, j) + (m - 8.5) × (S(2, j) - S(1, j)) / 6, where j = n;

[0077] Similarly, for partitions located in other internal areas, linear interpolation is performed using the same principle. That is, a weighted average is calculated based on the distance ratio between the target LED partition and the two nearest temperature sampling points. This can be expressed by the formula: Q(m, n) = y1 + (m - x1)×(y2 - y1) / (x2 - x1), where y1 and y2 are the temperature sampling values ​​of the first and second temperature sampling points adjacent to the target LED partition (m, n), and x1 and x2 are the x-coordinate values ​​of the first and second temperature sampling points adjacent to the target LED partition (m, n).

[0078] Using the bilinear interpolation algorithm described above, the ambient temperature of each LED zone (e.g., 192 zones) can be calculated from a limited number of temperature sampling points (e.g., 36), achieving the technical effect of high-precision coverage with fewer sampling points.

[0079] It should be noted that in this embodiment of the invention, the ambient temperature of the target LED partition is obtained by weighted averaging based on the distance ratio between the target LED partition and the two nearest sampling points. However, this invention does not limit this, and the ambient temperature of the target LED partition can also be obtained by weighted averaging based on the distance ratio between the target LED partition and the three or four nearest sampling points.

[0080] The main control unit (MCU) determines the corresponding compensation amount by looking up a table based on the ambient temperature Q(m, n) of each LED zone, and adjusts the drive signal of each LED zone accordingly. Specifically, the MCU internally stores a preset temperature-duty cycle compensation table or temperature-brightness compensation curve. The MCU looks up the compensation table or curve based on the ambient temperature to obtain the corresponding compensation amount, and generates adjusted drive information (e.g., backlight information including updated duty cycle), and then sends the drive information to the corresponding driver chip 20.

[0081] The communication circuit 22 of the driver chip 20 receives the driving information, and the driving signal generation circuit 23 generates a corresponding driving signal (e.g., a PWM signal) based on the driving information to drive the corresponding LED zone. The brightness of the LED zone is adjusted by adjusting the duty cycle of the PWM signal, thereby compensating for brightness drift and color shift caused by temperature changes.

[0082] In this embodiment, temperature sampling is performed once on the temperature sampling element within each frame period (i.e., each frame image display period) to obtain the ambient temperature and core temperature of each LED partition corresponding to each frame, thereby achieving frame-by-frame temperature compensation update. Since temperature changes have thermal inertia, the frame-by-frame update compensation strategy can meet the display accuracy requirements.

[0083] In summary, this embodiment provides a backlight driving system and its ambient temperature acquisition method. The system integrates the temperature detection circuit within the backlight driving chip. The driving chip only needs one temperature detection pin connected to an external temperature sampling element to complete the acquisition and digitization of the temperature signal. The main control unit reads the temperature registers of each driving chip through the communication bus to obtain the temperature value of each sampling point, and then uses a bilinear interpolation algorithm to calculate the ambient temperature of each LED zone from the finite number of sampling points.

[0084] The technical advantages of this embodiment are as follows: First, the temperature detection circuit is integrated inside the driver chip, eliminating the need for a separate temperature detection chip or complex peripheral circuits, thus reducing system cost and PCB layout complexity. Second, the layout of uniformly distributed NTC thermistors on the LED strip and physically isolated from the driver chip and LED zones avoids interference from power device heating on temperature sampling, ensuring the accuracy of ambient temperature detection. Third, through a bilinear interpolation algorithm, the technical effect of accurately estimating the ambient temperature of a large number of LED zones (e.g., 192) with a small number of temperature sampling points (e.g., 36) is achieved, striking a good balance between system cost and temperature detection accuracy. Compared to the existing technology where a single temperature sensor represents a large area of ​​temperature, this embodiment, through uniformly distributed sampling points combined with an interpolation algorithm, can accurately reflect the actual ambient temperature of each LED zone, providing an accurate data foundation for subsequent temperature compensation.

[0085] Furthermore, in another implementation, after obtaining the ambient temperature of each LED zone, the main control unit MCU also calculates the power temperature rise C(m, n) based on the real-time power of each LED zone, and superimposes the ambient temperature and the power temperature rise C(m, n) to obtain the core temperature Core(m, n).

[0086] The power temperature rise C(m, n) of each LED zone is obtained by multiplying the average power P_avg(m, n) of the LED zone by the thermal resistance Rth_LED of the LED beads in the LED zone: C(m, n) = P_avg(m, n) × Rth_LED, where Rth_LED is the thermal resistance of the LED bead (unit: °C / W), which can be obtained from the LED bead's datasheet.

[0087] The average power P_avg(m, n) is obtained by multiplying the duty cycle Duty of the current flowing through the LED partition, the peak current I_peak, and the forward voltage drop Vf of the LED in the LED partition when it is in the on state: P_avg(m, n) = Duty × I_peak × Vf.

[0088] The power temperature rise C(m, n) is superimposed on the ambient temperature Q(m, n) corresponding to the LED partition to obtain the core temperature Core(m, n) of the LED in the LED partition: Core(m, n) = Q(m, n) + C(m, n), where Core(m, n) is the core temperature of the (m, n)th LED partition, Q(m, n) is the ambient temperature of the LED partition, and C(m, n) is the power temperature rise of the LED partition.

[0089] In a preferred embodiment, the main control unit (MCU) includes an ambient temperature module, a power temperature rise module, a core temperature module, and a compensation module. The ambient temperature module calculates the ambient temperature Q(m, n) for each LED partition based on the temperature sampling signals and locations of each temperature sampling element. The power temperature rise module obtains the average power P_avg(m, n) of each LED partition based on the product of the duty cycle (Duty), peak value (I_peak), and LED voltage drop (Vf) of that LED partition, and multiplies this average power by the thermal resistance (Rth_LED) of the LED beads within that LED partition to obtain the power temperature rise C(m, n). The core temperature module superimposes the ambient temperature Q(m, n) and the power temperature rise C(m, n) to obtain the core temperature Core(m, n). The compensation module looks up the compensated drive information from a table based on the core temperature Core(m, n) and sends the drive information to the corresponding driver chip 20.

[0090] The main control unit (MCU) determines the corresponding compensation amount by looking up a table based on the core temperature (Core, n) of each LED zone, and adjusts the drive signal of each LED zone accordingly. Specifically, the MCU internally stores a preset temperature-duty cycle compensation table or temperature-brightness compensation curve. The MCU looks up the compensation table or curve based on the core temperature according to the ambient temperature to obtain the corresponding compensation amount, and generates adjusted drive information (e.g., backlight information including updated duty cycle), and then sends the drive information to the corresponding driver chip 20.

[0091] In summary, this embodiment provides a temperature compensation control method based on core temperature. After obtaining the ambient temperature of each LED zone, the main control unit calculates the power temperature rise of each LED zone based on its real-time power, and then superimposes the ambient temperature and the power temperature rise to obtain the core temperature of the LED. The main control unit looks up the compensated driving information based on the core temperature and sends it to the corresponding driver chip, which then generates an adjusted driving signal to drive the LED zone.

[0092] The technical advantages of this embodiment are as follows: First, by superimposing ambient temperature and power temperature rise, the junction temperature of the LED beads is accurately reflected, rather than simply measuring the ambient temperature, providing a more accurate basis for temperature compensation. Second, since the driving current and duty cycle of different LED zones are different, their power temperature rises are also different. This embodiment achieves differentiated power temperature rise calculation and independent compensation for each zone. Third, the main control unit achieves compensation through a lookup table, resulting in a fast response speed, suitable for real-time temperature compensation scenarios. Fourth, by performing temperature sampling and compensation update once per frame cycle, temperature tracking accuracy is ensured while avoiding excessive occupation of system resources. Compared with existing technologies that only consider ambient temperature or use a uniform compensation coefficient, this embodiment comprehensively considers both ambient temperature and self-heating effects, achieving more accurate temperature compensation and thus more effectively reducing the color shift of the LED array.

[0093] Figure 2 A schematic diagram of the backlight driving system structure according to a second embodiment of the present invention is shown. Figure 2 As shown, this embodiment provides a different connection method between the driver chip and the temperature sampling element compared to Embodiment 1.

[0094] In this embodiment of the invention, each driver chip 20 is connected to multiple temperature sampling elements 30, and each temperature sampling element 30 is respectively disposed at a different position of the light strip driven by the driver chip 20. The driver chip 20 is electrically coupled to each temperature sampling element 30 through multiple temperature detection pins to obtain more refined temperature distribution information within the area driven by the driver chip 20.

[0095] In a preferred embodiment, each driver chip is connected to multiple temperature sampling elements 30, and each temperature sampling element 30 is disposed at a different position on the light strip driven by the driver chip 20 to obtain more refined temperature distribution information. Preferably, each temperature sampling element is electrically coupled to the driver chip 20 whose physical location is closest to it. In this embodiment, multiple driving pins in the driver chip 20 can be multiplexed as temperature sampling pins.

[0096] The correspondence between the driver chip 20 and the temperature sampling element 30 can be flexibly selected according to the actual application scenario, such as the size of the backlight system, the number of partitions, and the cost budget. This invention does not limit this. For example, each driver chip 20 can be connected to two temperature sampling elements 30, or each driver chip 20 can be connected to three or more temperature sampling elements.

[0097] Since the driver chip 20 is typically configured with only a limited number of temperature detection pins (e.g., one or two), when a single driver chip 20 needs to connect to multiple temperature sampling elements, in a preferred embodiment, at least some of the temperature detection pins of the driver chip 20 use a time-division sampling method to obtain the temperature values ​​of each temperature sampling element 30.

[0098] refer to Figure 2 Specifically, according to control logic, the driver chip 20 sequentially selects different temperature detection channels in the channel selection module 40 within different time periods to connect the corresponding temperature sampling element 30 to the temperature detection circuit 21 inside the driver chip 20. Within a given time period, only one temperature sampling element 30 is connected to the temperature detection circuit 21. The driver chip 20 samples and performs analog-to-digital conversion on the voltage of this temperature sampling element 30, and stores the converted digital temperature information in the corresponding temperature register. Subsequently, the driver chip 20 switches to the next time period to sample the next temperature sampling element 30. Through this time-division sampling method, the driver chip 20 sequentially completes temperature acquisition from multiple temperature sampling elements within one frame period.

[0099] It should be noted that the sampling frequency of each temperature sampling element 30 can be set according to actual application requirements. Preferably, the driver chip 20 performs sampling once for each of the temperature sampling elements connected to it within one frame period to ensure the integrity and synchronization of temperature data in each frame.

[0100] The technical advantages of this embodiment are as follows: First, the one-to-many correspondence between the driver chip and the temperature sampling elements can obtain more refined temperature distribution information, which is suitable for high-end display applications with large size, high partition density, and higher requirements for color deviation. Furthermore, the number of temperature sampling elements can be flexibly selected according to the actual application scenario, exhibiting high scalability. Second, this embodiment, through time-division sampling, allows a single driver chip to utilize a limited number of temperature detection pins to connect to multiple temperature sampling elements. Without significantly increasing chip pin overhead, it improves the spatial resolution of temperature sampling, providing denser temperature sampling points for subsequent bilinear interpolation algorithms, thereby further improving the accuracy of calculating the ambient temperature of each LED partition.

[0101] Figure 3 A schematic flowchart of the backlight driving method of the present invention is shown. Figure 3 As shown, the backlight driving method includes the following steps:

[0102] Step S1: Set the temperature sampling element at different positions in the LED array.

[0103] The temperature sampling element, for example, is a thermistor (NTC or PTC), which is disposed on the LED strips of the LED array and located between adjacent LED zones. The temperature sampling elements are evenly distributed in the LED array to obtain temperature sampling signals, and they are not physically in contact with the driver chip or the LED zones to avoid interference from the driver chip's own heat generation and the LED power generation.

[0104] Step S2: Obtain the ambient temperature of different LED zones based on the temperature sampling signal.

[0105] Each temperature sampling element converts the detected temperature into an electrical signal. The driver chip acquires this electrical signal through its temperature detection pin, converts it into digital temperature information, and then reports it to the main control unit MCU.

[0106] Specifically, the ambient temperature of the LED partition is obtained based on the temperature sampling signal of at least one temperature sampling element adjacent to the target LED partition. In a preferred embodiment, each temperature sampling element is marked with corresponding position coordinates according to its physical position in the LED array; a temperature sampling element at the corresponding position is selected based on the physical position of the target LED partition in the LED array, and the ambient temperature of the target LED partition is obtained based on its sampling signal.

[0107] Furthermore, for LED partitions located in the boundary region, the temperature sampling signal of the temperature sampling element closest to the LED partition and located on the boundary is selected as the ambient temperature of the LED partition; for LED partitions not located in the boundary region, multiple temperature sampling elements closest to the LED partition are selected with the location coordinates of the LED partition as the center, and the ambient temperature of the LED partition is calculated by weighting the temperature sampling signals of each temperature sampling element and the distance between the LED partition and each temperature sampling element.

[0108] Preferably, the temperature sampling element is sampled once in each frame period to obtain the ambient temperature of each LED partition corresponding to each frame.

[0109] Step S3: Calculate the power temperature rise of each LED zone based on its real-time power.

[0110] Specifically, the power temperature rise of each LED zone is obtained by multiplying the average power of the LED zone by the thermal resistance of the LED beads within that LED zone. The average power of the LED zone is obtained by multiplying the duty cycle and peak value of the current flowing through the LED zone by the LED voltage drop of that LED zone.

[0111] Step S4: Add the power temperature rise to the ambient temperature to obtain the core temperature.

[0112] The core temperature of the LED partition is obtained by superimposing the power temperature rise onto the ambient temperature corresponding to the LED partition.

[0113] Step S5: Adjust the driving signals of different LED zones according to at least the ambient temperature or core temperature, thereby reducing the color shift of the LED array.

[0114] The main control unit in the backlight driving system determines the compensation amount corresponding to the ambient temperature or core temperature based on the preset temperature-duty cycle compensation table or temperature-brightness compensation curve, and generates an adjustment signal accordingly and sends it to the corresponding driver chip. The driver chip generates the driving signal based on the adjustment signal.

[0115] Alternatively, the main control unit updates the driving information corresponding to the ambient temperature or core temperature according to a preset temperature-duty cycle table or temperature-brightness curve, and sends the driving information to the corresponding driving chip, which then generates the driving signal based on the driving information.

[0116] In summary, this embodiment provides a backlight driving method. This method distributes temperature sampling elements throughout the LED array, obtains the ambient temperature of different LED zones based on the temperature signals from each sampling point, and adjusts the driving signal at least according to the ambient temperature, thereby reducing color shift in the LED array. The method also includes calculating the power temperature rise based on the real-time power of each LED zone, superimposing the ambient temperature and the power temperature rise to obtain the core temperature, and performing temperature compensation based on the core temperature. Compared to existing technologies that use a single or a small number of temperature sensors for unified compensation, this embodiment effectively overcomes the technical defects of traditional solutions caused by inaccurate temperature detection and insufficient compensation through the distributed layout of temperature sampling elements and independent temperature detection and compensation for each LED zone.

[0117] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. For those skilled in the art, the present invention can be modified and varied in various ways. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of protection of the present invention.

Claims

1. A backlight driving method for driving an LED array, characterized in that, include: Temperature sampling elements are placed at different positions in the LED array to obtain temperature sampling signals; The ambient temperature of different LED zones is obtained based on the temperature sampling signal. The drive signals for different LED zones are adjusted based on the ambient temperature to reduce the color shift of the LED array.

2. The backlight driving method according to claim 1, characterized in that, The ambient temperature of the LED partition is obtained based on the temperature sampling signal of at least one of the temperature sampling elements adjacent to the target LED partition.

3. The backlight driving method according to claim 1, characterized in that, Based on the physical location of each temperature sampling element in the LED array, each temperature sampling element is marked with a corresponding position coordinate; based on the physical location of the target LED partition in the LED array, a temperature sampling element at the corresponding position is selected, and the ambient temperature of the target LED partition is obtained based on its sampling signal.

4. The backlight driving method according to claim 1, characterized in that, The temperature sampling elements are evenly distributed in the LED array and are disposed on the LED strips of the LED array. The temperature sampling elements are located between adjacent LED partitions and are not physically in contact with the driver chip and the LED partitions.

5. The backlight driving method according to claim 1, characterized in that, For LED partitions located in the boundary region, the temperature sampling signal of the temperature sampling element that is closest to the LED partition and located on the boundary is selected as the ambient temperature of the LED partition.

6. The backlight driving method according to claim 1, characterized in that, For LED zones not located in the boundary area, multiple temperature sampling elements closest to the LED zone are selected with the location coordinates of the LED zone as the center. The ambient temperature of the LED zone is calculated by weighting the temperature sampling signals of each temperature sampling element and the distance between the LED zone and each temperature sampling element.

7. The backlight driving method according to claim 1, characterized in that, The power temperature rise of each LED partition is calculated based on its real-time power. This power temperature rise is then added to the ambient temperature corresponding to the LED partition to obtain the core temperature of the LED partition. Based on this core temperature, the drive signal of the LED partition is adjusted.

8. The backlight driving method according to claim 7, characterized in that, The power temperature rise of each LED zone is obtained by multiplying the average power of the LED zone by the thermal resistance of the LED beads in the LED zone.

9. The backlight driving method according to claim 8, characterized in that, The average power of the LED partition is obtained by multiplying the duty cycle and peak value of the current flowing through the LED partition by the LED voltage drop of the LED partition.

10. The backlight driving method according to claim 1 or 7, characterized in that, The main control unit in the backlight driving system determines the compensation amount corresponding to the ambient temperature or core temperature based on the preset temperature-duty cycle compensation table or temperature-brightness compensation curve, and generates an adjustment signal accordingly and sends it to the corresponding driver chip. The driver chip generates the driving signal based on the adjustment signal.

11. The backlight driving method according to claim 1 or 7, characterized in that, The main control unit in the backlight driving system updates the driving information corresponding to the ambient temperature or core temperature according to the preset temperature-duty cycle table or temperature-brightness curve, and sends the driving information to the corresponding driving chip. The driving chip generates the driving signal according to the driving information.

12. The backlight driving method according to claim 4, characterized in that, The driving chip includes a temperature detection circuit, a communication circuit, and a driving signal generation circuit. The temperature detection circuit receives the temperature sampling signal and transmits it to the main control unit through the communication circuit. The main control unit obtains a corresponding adjustment signal based on the temperature sampling signal. The adjustment signal is transmitted to the driving signal generation circuit through the communication circuit, and the driving signal is adjusted by the driving signal generation circuit.

13. The backlight driving method according to claim 4, characterized in that, Each of the driver chips corresponds to at least one temperature sampling element.

14. The backlight driving method according to claim 1, characterized in that, Temperature sampling is performed once per frame period on the temperature sampling element to obtain the ambient temperature of each LED partition corresponding to each frame.

15. A backlight driving system for driving an LED array, characterized in that, include: Multiple temperature sampling elements are distributed at different positions in the backlight driving system to acquire multiple temperature sampling signals corresponding to different positions; Multiple driver chips are connected to the main control unit and report the multiple temperature sampling signals. The main control unit obtains the ambient temperature of different LED zones based on the multiple temperature sampling signals, and adjusts the driving signals of different LED zones based on at least the ambient temperature, thereby reducing the color shift of the LED array.

16. The backlight driving system according to claim 15, characterized in that, The main control unit obtains the ambient temperature of the LED partition based on the temperature sampling signal of at least one of the temperature sampling elements adjacent to the target LED partition.

17. The backlight driving system according to claim 15, characterized in that, The main control unit marks the position of each temperature sampling element according to its physical position in the LED array, so that each temperature sampling element has a corresponding position coordinate; according to the physical position of the target LED partition in the LED array, the temperature sampling element at the corresponding position is selected, and the ambient temperature of the target LED partition is obtained according to its sampling signal.

18. The backlight driving system according to claim 15, characterized in that, The temperature sampling elements are evenly distributed in the LED array and are disposed on the LED strips of the LED array. The temperature sampling elements are located between adjacent LED partitions and do not contact the driver chip or the LED partitions.

19. The backlight driving system according to claim 15, characterized in that, For LED partitions located in the boundary region, the temperature sampling signal of the temperature sampling element that is closest to the LED partition and located on the boundary is selected as the ambient temperature of the LED partition.

20. The backlight driving system according to claim 15, characterized in that, For LED zones not located in the boundary area, multiple temperature sampling elements closest to the LED zone are selected with the location coordinates of the LED zone as the center. The ambient temperature of the LED zone is calculated by weighting the temperature sampling signals of each temperature sampling element and the distance between the LED zone and each temperature sampling element.

21. The backlight driving system according to claim 15, characterized in that, The main control unit also calculates the power temperature rise of each LED partition based on the real-time power of each LED partition, adds the power temperature rise to the ambient temperature corresponding to the LED partition to obtain the core temperature of the LED partition, and adjusts the drive signal of the LED partition based on the core temperature.

22. The backlight driving system according to claim 21, characterized in that, The main control unit includes: The ambient temperature module is used to calculate the ambient temperature corresponding to each LED zone based on the temperature sampling signals and locations of each temperature sampling element. The power temperature rise module is used to obtain the average power of the LED zone based on the product of the duty cycle and peak value of the current of each LED zone and the LED voltage drop of the LED zone, and multiply the average power by the thermal resistance of the LED beads in the LED zone to obtain the power temperature rise of the LED zone. The core temperature module is used to superimpose the ambient temperature and the power temperature rise to obtain the core temperature.

23. The backlight driving system according to claim 15 or 21, characterized in that, The main control unit also includes a compensation module, which is used to obtain the compensated drive information by looking up a table according to the ambient temperature or core temperature, and send the drive information to the corresponding drive chip, and the drive chip generates the drive signal according to the drive information.

24. The backlight driving system according to claim 15, characterized in that, Each of the driving chips corresponds to at least one of the temperature sampling elements. The driving chip is electrically coupled to the corresponding temperature sampling element through its temperature detection pin to collect the ambient temperature at the location of the temperature sampling element.

25. The backlight driving system according to claim 24, characterized in that, Each of the driving chips is connected to a temperature sampling element, which is attached to the area of ​​the light strip driven by the driving chip and is arranged adjacent to the LED partitions in the same area.

26. The backlight driving system according to claim 24, characterized in that, Each of the driving chips is connected to a plurality of temperature sampling elements, and each temperature sampling element is attached to a different position of the light strip driven by the driving chip.

27. The backlight driving system according to claim 15, characterized in that, The temperature detection module uses the frame period of the backlight driving system as the sampling period, and performs temperature sampling once on the temperature sampling element in each frame period to obtain the temperature sampling value corresponding to each frame.

28. The backlight driving system according to claim 26, characterized in that, The driver chip sequentially collects the temperature sampling signals of each temperature sampling element using a time-division sampling method.

29. The backlight driving system according to claim 28, characterized in that, It also includes a channel selection module, which is coupled between the temperature detection circuit and multiple temperature sampling elements. The control logic of the driver chip controls the channel selection module to select different temperature detection channels in different time periods, so that only one temperature sampling element is connected to the temperature detection circuit in a certain time period.

30. The backlight driving system according to claim 28, characterized in that, The driving chip performs sampling once for each of the temperature sampling elements connected to it within a frame period to obtain the temperature sampling value of each temperature sampling element corresponding to each frame.

Images