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Composite SPWM algorithm for constant-current LED driving chip

An LED-driven, composite technology, applied in instruments, static indicators, etc., can solve the problems of difficult to achieve uniform dispersion, low PWM refresh rate, low gray level, etc., to achieve uniform dispersion is simple, easy and adaptive Grouping is simple and easy to implement, and the effect of improving visual fluency

Active Publication Date: 2021-06-18
CHINA KEY SYST & INTEGRATED CIRCUIT
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Problems solved by technology

[0006] The purpose of the present invention is to provide a compound SPWM algorithm for constant current LED drive chips to solve the problems of traditional PWM with low refresh rate, low gray level, low gray spots, unreasonable grouping, and difficulty in realizing even dispersal

Method used

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Embodiment 1

[0026] The invention provides a compound SPWM algorithm for a constant current LED drive chip, figure 1 It is a schematic diagram of the SPWM algorithm of the constant current LED driver chip. PWM dimming technology adjusts the brightness of LED lights by changing the duty cycle of PWM pulses. In the SPWM algorithm, the display time of one frame is broken up into several groups, and the original PWM pulse width is evenly distributed among the broken up groups while keeping the display gray value unchanged, that is, while maintaining the duty cycle While remaining unchanged, the number of channel openings is increased, thereby improving the display refresh rate.

[0027] One of the disadvantages of the traditional SPWM algorithm is that problems such as color blocks and pitting are prone to appear when the gray is low. The reason is that after the PWM pulse is broken up, the single channel opening time is shortened, and the analog channel of the chip has no time to open and cl...

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Abstract

The invention discloses a composite SPWM algorithm for a constant-current LED driving chip, and belongs to the field of LED display. The method includes: setting a digit N, a refresh level G and an optimization level K of the display gray data; when the gray data is not smaller than 512, dividing the gray data into H-bit high-order data and L-bit low-order data, N = H + L; according to the refresh level G and the optimization level K, averagely distributing H-bit high-order data into 2L sub-cycles, and uniformly distributing L-bit low-order data into the 2L sub-cycles; when the gray scale data is smaller than 512, dividing the gray scale data into a high gray scale group and a low gray scale group according to the actual gray scale data, namely visual data and invisible data, and grouping the invisible data according to the gray scale data by taking the actual gray scale data as a group; according to the gray data and the optimization level K, scattering the whole display period, totally 2N clock periods, into gray data sub-periods, and according to the optimization level K, uniformly distributing the visible data and the invisible data into the sub-periods.

Description

technical field [0001] The invention relates to the technical field of LED display, in particular to a composite SPWM algorithm for a constant current LED drive chip. Background technique [0002] LED full-color display is a new type of information display media rapidly developed in the world in the 1990s. It combines modern high-tech and has a series of advantages such as low power consumption, long service life, environmental protection, bright colors, and wide viewing range. . Traditional large-screen LED display systems have encountered many problems, such as low refresh rate, afterimages, and uneven display. At present, there are roughly two ways to control the brightness of LEDs: one is to use analog circuits for dimming, which is to linearly change the current flowing through the LED; the other is digital dimming, which uses PWM control methods to change the brightness of the LED. The duty cycle of the driving current flowing through the LED thus changes the average...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G09G3/32
CPCG09G3/32Y02B20/40
Inventor 彭杰范学仕唐茂洁
Owner CHINA KEY SYST & INTEGRATED CIRCUIT
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