小点间距LED显示屏驱动芯片的研究

发布时间：2018-10-07 17:24

【摘要】：近年来,小点间距LED显示屏得到了快速发展,广泛应用于各行各业。在小点间距LED显示系统中,驱动芯片占有非常重要的作用,通过驱动控制电路来获得平稳的电流,从而使显示屏显示出细腻精美的图像视频信息。可见显示画面质量的好坏以及驱动电路性能的关键在于对显示驱动芯片的设计,具体体现在刷新频率和灰度等级两个指标。鉴于此,本文设计了一款满足小点间距LED显示屏显示需求的具有高刷新高灰阶特性的ICN2053驱动芯片。(1)针对小点间距LED显示屏的常见问题,如下鬼影、第一行偏暗、亮度不均、开路十字架、麻点等现象,在立足于已有的输出恒定电流的模拟电路基础上,本文提出了一系列解决方案。通过对16通道ICN2053驱动芯片的研究,并结合Verilog硬件描述语言对该款芯片的数字模块部分进行RTL设计,利用一些特殊的功能模块,如预充电电路模块、开路检测功能、电流增益调节、PWM优化等,就能够很好地解决这些常见问题。(2)针对刷新率问题,本设计采用了脉冲打散(SPWM)的新型PWM方式,通过内建双SRAM的存储模式对输入的灰度数据进行处理和优化,与传统驱动芯片相比,可以大大地提高显示屏的刷新率。另外,ICN2053芯片具有多个指令和配置寄存器,能够实现更多的控制和功能,比如可以实现打散组数可调,不同的打散组数能够实现不同的刷新率,有利于选择不同的方式控制LED显示屏,从而得到最合适的显示效果。ICN2053芯片的刷新率最高可以达到30720Hz,能够使显示屏有效避免闪烁及在高速摄影下出现条纹等不良现象的发生。(3)针对灰阶问题,ICN2053芯片支持1～32行扫,利用灰度时钟GCLK计数采样,能够实现16位65536级灰度数据的输出显示,理论上支持全彩显示屏红绿蓝形成约281万亿种颜色。同时,ICN2053芯片支持低灰度脉冲宽度优化,具有非常好的低灰显示效果,这对小点间距LED显示屏来说非常重要。这使得显示屏在低亮度下,仍能表现出高灰阶特性。本文对ICN2053芯片的设计采用了自顶向下的设计方法,在功能框架的基础上,划分模块并进行RTL设计、仿真、综合等步骤得到Netlist,再经过后端布局布线,实现芯片的版图和流片。最后,通过对ICN2053芯片的样片仿真和实验测试,结果基本满足设计要求,得出了ICN2053驱动芯片具有高刷新率、高灰阶特性及良好低灰显示效果的结论,可以完美支持小点间距LED显示屏工作,不会出现显示质量问题。
[Abstract]:In recent years, small dot spacing LED display screen has been rapidly developed, widely used in various industries. In the small dot spacing LED display system, the driver chip plays a very important role. By driving the control circuit to obtain a stable current, so that the display screen display exquisite image and video information. It can be seen that the key to the quality of the display picture and the performance of the drive circuit lies in the design of the display driver chip, which is embodied in the two indexes of refresh frequency and grayscale grade. In view of this, this paper designs a ICN2053 driver chip with high refresh and high gray scale to meet the demand of small dot spacing LED display screen display. (1) aiming at the common problems of small dot spacing LED display screen, the following is the ghost, the first line is dark, the brightness is uneven, Based on the existing analog circuits with constant output current, a series of solutions are proposed. Based on the research of 16-channel ICN2053 driver chip and Verilog hardware description language, the digital module of the chip is designed by RTL, and some special function modules, such as precharge circuit module, open circuit detection function, are used to design the digital module of the chip. The current gain adjustment and PWM optimization can solve these common problems well. (2) aiming at the problem of refresh rate, this design adopts a new type of PWM with pulse dispersion (SPWM). The input gray data is processed and optimized by the memory mode of built-in dual SRAM. Compared with the traditional drive chip, the refresh rate of the display screen can be greatly improved. In addition, the ICN2053 chip has multiple instructions and configuration registers, which can achieve more control and functions, such as the adjustable number of scattered groups, and the different refresh rates of different batching groups. It is advantageous to choose different ways to control the LED display, Therefore, the most suitable display effect. ICN2053 chip can achieve the highest refresh rate of 30720Hz. it can effectively avoid the occurrence of bad phenomena such as flicker and stripes under high-speed photography. (3) the ICN2053 chip supports 1 / 32 scan for gray-scale problems. By using the grayscale clock GCLK counting and sampling, the output display of 16-bit 65536 grayscale data can be realized, which theoretically supports the formation of about 281 trillion colors of full-color display screen red, green and blue. At the same time, the ICN2053 chip supports the optimization of the pulse width of low gray level, and has a very good effect of low gray display, which is very important for the small dot spacing LED display screen. This allows the display to display high grayscale characteristics at low brightness. In this paper, the top-down design method of ICN2053 chip is adopted. On the basis of the functional framework, the module is divided into modules and the RTL design, simulation and synthesis are carried out to get the Netlist, layout and routing through the back-end layout to realize the layout and flow sheet of the chip. Finally, through the simulation and experimental test of ICN2053 chip, the results basically meet the design requirements, and the conclusion that the ICN2053 driver chip has high refresh rate, high gray scale characteristic and good low ash display effect is obtained. Can support the small dot spacing LED screen work perfectly, does not have the display quality question.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN873

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