Frequency reduction control method in PWM dimming mode for LED backlight

Abstract

This invention discloses a frequency reduction control method in PWM dimming mode for LED backlighting. The method includes: dividing the brightness adjustment range of the LED backlight panel into multiple brightness intervals, and setting a corresponding PWM dimming signal control mode for each brightness interval; at least one of the multiple control modes includes: forming a PWM dimming signal group from n PWM dimming signal cycles, where n is greater than 1; resetting the duty cycle of the n PWM dimming signals in the PWM dimming signal group; the duty cycles of the n PWM dimming signals are respectively set to D1, D2, ..., D... n And when the dimming brightness is m, we have: m=(D1+D2+……+D n ) / n.

Description

Technical Field

[0001] This invention relates to the field of LED backlight driving technology, and in particular to a frequency reduction control method in PWM dimming mode for LED backlights. Background Technology

[0002] In current LCD screens, LEDs are widely used as the backlight source. LED backlight brightness control typically employs two dimming modes: DC regulation and PWM regulation. PWM regulation offers advantages such as consistent current and low heat generation. However, when using PWM mode to control LED backlight brightness, the parasitic resistance and capacitance differ between different LED light-emitting channels, resulting in inconsistent current rise and fall times for each channel. Figure 1 As shown.

[0003] When the brightness is high, the duty cycle of the corresponding PWM dimming signal is large. At this time, the rise or fall time of the LED conduction current is relatively small compared with the high level duration of the PWM dimming signal. As a result, the brightness difference between channels will not be perceived by the human eye.

[0004] When the brightness is low, the corresponding PWM dimming signal has a small duty cycle, meaning the high-level duration of the PWM dimming signal itself is relatively short. Therefore, the rise or fall time of the current's rising or falling edge accounts for a larger proportion of the high-level duration of the PWM dimming signal. Consequently, the difference in rising and falling edges between different channels can lead to significant brightness differences. Furthermore, the higher the frequency of the PWM dimming signal, the shorter the high-level time of the PWM dimming signal, and the more pronounced this effect becomes.

[0005] Therefore, there is a need in this field for a new control method that can effectively suppress the brightness difference of different LED light-emitting channels under low brightness conditions in LED backlighting under PWM dimming mode. Summary of the Invention

[0006] Based on the above technical objectives, this invention provides a frequency reduction control method in PWM dimming mode for LED backlighting, the method comprising:

[0007] The brightness adjustment range of the LED backlight panel is divided into multiple brightness ranges, and each brightness range is set with a corresponding PWM dimming signal control mode.

[0008] At least one of the plurality of control modes includes:

[0009] A PWM dimming signal group is formed by n cycles of PWM dimming signals, where n is greater than 1;

[0010] The duty cycles of the n PWM dimming signals within the PWM dimming signal group are reset; the duty cycles of these n PWM dimming signals are set to D1, D2, ..., D... n And when the dimming brightness is m, we have:

[0011] m=(D1+D2+……+D n ) / n.

[0012] In one embodiment, there exists a minimum value among the n duty cycle values ​​of the n PWM dimming signals.

[0013] In one embodiment, the minimum value is zero.

[0014] In one embodiment, different brightness ranges are provided between different LED channels.

[0015] In one embodiment, the method includes reducing the frequency of the PWM signal in all control modes.

[0016] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the description, claims, and drawings. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0018] Figure 1 This is a schematic diagram of the PWM dimming signal waveform in existing technology;

[0019] Figure 2 This is a schematic diagram of a PWM dimming signal waveform according to an embodiment of the present invention;

[0020] Figure 3 This is a flowchart illustrating a frequency reduction control method under PWM dimming mode according to an embodiment of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0022] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this invention, the first element, component, area, layer, or portion discussed below may be referred to as a second element, component, area, layer, or portion. And when a second element, component, area, layer, or portion is discussed, it does not imply that the first element, component, area, layer, or portion necessarily exists in this invention.

[0023] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein for convenience of description to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, then the element or feature described as “below,” “under,” or “below” other elements or features will be oriented “above” other elements or features. Therefore, the exemplary terms “below” and “under” can include both above and below orientations. The device may be otherwise oriented (rotated 90 degrees or otherwise) and the spatial descriptive terms used herein will be interpreted accordingly.

[0024] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “including,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0025] Example 1

[0026] like Figure 2-3As shown, the frequency reduction control method in the PWM dimming mode of the present invention includes:

[0027] S100, the brightness adjustment range of the LED backlight panel is divided into multiple brightness intervals, and each brightness interval is set with a corresponding PWM dimming signal control mode. In this embodiment, the overall brightness adjustment range of the LED backlight panel from 0% to 100% is divided into a first brightness interval (0%, 5%) and a second brightness interval (5%, 100%). A first control mode is used for the first brightness interval, and a second control mode is used for the second brightness interval.

[0028] S101, at least one of the multiple control modes includes forming a PWM dimming signal group from multiple PWM dimming signal cycles. For example, in this embodiment, when the dimming brightness m (i.e., the brightness that the current LED backlight channel needs to display is m) is in the first brightness range, the PWM dimming signal is divided into a PWM dimming signal group consisting of four PWM dimming cycles, with each PWM dimming signal group including four PWM dimming cycles, i.e., including four PWM dimming signals. Meanwhile, in this embodiment, the second control mode sampled by other LED channels with dimming brightness in the second brightness range maintains the original PWM dimming control method, i.e., no processing is performed on the PWM dimming signal.

[0029] S102, reset the duty cycles of multiple PWM dimming signals within the PWM dimming signal group. When the PWM dimming signal group consists of n PWM dimming signal cycles, the duty cycles of these n PWM dimming signals are set to D1, D2, ..., D... n And when the dimming brightness is m, then:

[0030] m=(D1+D2+……+D n ) / n.

[0031] In this embodiment, when the dimming brightness m is 3%, the duty cycles of the four PWM dimming signals are set to D1 = 5%, D2 = 5%, D3 = 2%, and D4 = 0%, respectively, ensuring that the average duty cycle within each PWM dimming signal group remains 3%. However, for the PWM dimming signals with duty cycles D1 = 5% and D2 = 5%, the proportion of LED current change edges and high levels is reduced, thereby improving the brightness difference between different LED channels. Furthermore, since the duty cycle D4 = 0%, the frequency of the LED current envelope can be reduced.

[0032] In this embodiment, the number of PWM dimming cycles n in each PWM dimming signal group is 4. However, those skilled in the art should understand that the value of n can be varied as needed. Any value greater than 1 can be used to implement the technical solution of this invention.

[0033] In this embodiment, the overall brightness adjustment range of the LED backlight panel from 0% to 100% is divided into a first brightness range and a second brightness range. However, those skilled in the art should understand that this invention is not limited to dividing the brightness range into two brightness ranges; the invention can divide the brightness range into more brightness ranges as needed.

[0034] In this embodiment, a first control mode is adopted for the low-brightness first brightness range, which is to form a PWM dimming signal group by composing multiple PWM dimming signal cycles. However, those skilled in the art will understand that, according to actual engineering needs, when a more refined division of the brightness range is required, the first control mode can be implemented in multiple brightness ranges. Specifically, the first control mode can be implemented in multiple low-brightness ranges.

[0035] In this embodiment, the multiple reset duty cycles within the PWM dimming signal group can be set to zero duty cycle or not. Those skilled in the art should understand that setting a zero duty cycle can effectively reduce the current envelope frequency. Furthermore, this embodiment does not limit the arrangement order of the PWM signals for each duty cycle within the group; this arrangement order does not affect the average duty cycle value of the PWM dimming signal group.

[0036] In this embodiment, at least one of the multiple reset duty cycle values ​​is the minimum value relative to the other duty cycle values. Only in this way can the effect of increasing the other duty cycle values ​​be achieved, thereby improving the influence of rising and falling edges on the duty cycle.

[0037] The method of the present invention further includes reducing the frequency of the PWM signal in all control modes.

[0038] This invention can be any possible system, method, and / or computer program product at the level of integrated technical detail. The computer program product may include a computer-readable storage medium (or media) having computer-readable program instructions thereon for causing a processor to execute aspects of the invention.

[0039] A computer-readable storage medium can be a tangible device that can hold and store instructions used by an instruction execution device. The computer-readable storage medium can be, for example, but not limited to, electronic storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any suitable combination of the foregoing. A non-exhaustive list of more specific examples of computer-readable storage media includes the following: a portable computer floppy disk, a hard disk, random access memory (RAM), read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), a portable optical disc read-only memory (CD-ROM), a digital universal disc (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or raised structure in a groove on which instructions are recorded, and any suitable combination of the foregoing. A computer-readable storage medium, as used herein, should not be construed as a transient signal itself, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses through fiber optic cables), or electrical signals transmitted through wires.

[0040] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to a suitable computing / processing device, or via a network, such as the Internet, a local area network (LAN), a wide area network (WAN), and / or a wireless network, to an external computer or external storage device. This network may include copper transmission cables, optical fiber transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards them to a computer-readable storage medium within the suitable computing / processing device.

[0041] Computer-readable program instructions used to perform the operations of this invention may be assembler instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state setting data, configuration data for integrated circuits, or source code or object code written in one or more programming languages ​​and any combination of procedural programming languages. The computer-readable program instructions may be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer, partially on a remote computer, or entirely on a remote computer or server. In the latter case, the remote computer may be connected to the user's computer via any type of network including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., via the Internet through an Internet service provider). In some embodiments, electronic circuitry including, for example, programmable logic circuitry, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs) may execute the computer-readable program instructions by utilizing state information from the computer-readable program instructions to personalize the electronic circuitry and thereby perform aspects of the invention.

[0042] This document describes aspects of the invention with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer-readable program instructions.

[0043] These computer-readable program instructions can be provided to a computer's processor or other programmable data processing device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing device, create a mechanism for implementing flowcharts and / or blocks. Figure 1 Means of the functions / actions specified in one or more blocks. These computer-readable program instructions may also be stored in a computer-readable storage medium capable of guiding a computer, a programmable data processing apparatus and / or other apparatus operating in a particular manner, such that the computer-readable storage medium storing the instructions includes an article of manufacture comprising instructions for implementing aspects of the functions / actions specified in the flowchart and / or block diagram blocks.

[0044] Computer-readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other apparatus to cause a series of operational steps to be performed on the computer, other programmable devices or other apparatuses for producing computer-implemented processes, such that the instructions executed on the computer, other programmable devices or other apparatuses perform the functions / actions specified in the flowchart and / or block diagram boxes.

[0045] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of instructions comprising one or more executable instructions for implementing a specified logical function. In some alternative implementations, the functions indicated in a block may occur outside the order indicated in the diagram. For example, two blocks shown consecutively may actually be completed as a single step, executed concurrently, substantially concurrently, in a manner that overlaps partially or entirely in time, depending on the functions involved, or sometimes these blocks may be executed in reverse order. It will also be noted that each block illustrated in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented by a dedicated hardware-based system that performs the specified function or action or executes a combination of dedicated hardware and computer instructions.

[0046] This application describes embodiments with reference to flowchart illustrations and / or block diagrams of methods, apparatus (devices), and computer program products according to embodiments of this application. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0047] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0048] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

Claims

1. A frequency reduction control method in PWM dimming mode for LED backlighting, characterized in that, The method includes: The brightness adjustment range of the LED backlight panel is divided into a first brightness range (0%, 5%) and a second brightness range (5%, 100%). A first control mode is used for the first brightness range and a second control mode is used for the second brightness range. The first control mode is: A PWM dimming signal group is formed by combining n PWM dimming signal cycles; The duty cycles of the n PWM dimming signals within the PWM dimming signal group are reset; the reset duty cycles of the PWM dimming signals are set to D1, D2, ..., Dn respectively; and when the dimming brightness is m, we have: m = (D1 + D2 + ... + Dn) / n; The second control mode is to maintain the original PWM dimming control method; Among the n duty cycle values ​​of the reset PWM dimming signal, there is a minimum value, and n is greater than 1.

2. The method according to claim 1, characterized in that, The minimum value is zero.

3. The method according to claim 1, characterized in that, Different brightness ranges are set between different LED channels.

4. The method according to claim 1, characterized in that, The method includes reducing the frequency of the PWM signal in all control modes.

5. An LED backlight panel, characterized in that, The LED backlight panel uses the method described in any one of claims 1-4 to adjust the backlight brightness.

6. An LED display panel, characterized in that, The LED display panel uses the LED backlight panel as described in claim 5.

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