无源液晶光学器件的低成本驱动电路设计

Design of low-cost drive circuit for passive liquid crystal optical device

为了实现多路无源液晶光学器件的驱动,设计开发了低成本、低复杂度及幅频可调的多路驱动电路。首先,为了便于控制液晶器件,在PC机和驱动板之间采用USB数据传输方式进行控制信号的传输。其次,驱动板卡采用母板加多子板模式,每个子板可输出32路驱动信号,其可依据实际需求灵活选取子板数目,从而降低成本。母板与子板均采用STM32作为主控芯片,子板通过SPI接口与母板进行数据传输。每个子板通过2个SPI接口将数据分组分发给DAC芯片,每个DAC芯片可控制16路数模转换,最终实现192路模拟信号的输出。最后,进行制板和测试。结果显示,输出模拟电压与灰度值符合线性比例关系,其绝对误差在0.010 V左右,符合10 bit、1024级电压灰度值调制精度。该驱动板卡可以实现多路驱动信号的输出,满足多路无源液晶光学器件驱动控制的需求。

In order to realize the driving of multi-channel passive liquid crystal optical devices,the driving circuit with low cost,low complexity and adjustable amplitude and frequency is designed and developed.Firstly,to facilitate the control of the liquid crystal device,the USB data transmission method is used to transmit the control signal between the PC and the driver board.Secondly,the driver board adopts the combination of the mother board and daughter board,and each daughter board can output 32 driving signals,which can flexibly select the number of daughter board according to actual needs,thereby reducing the cost.The mother board and the daughter board both use STM32 as the main control chip,and the daughter board communicates with the mother board through the SPI interface.Each daughter board distributes data packets to the DAC chip through 2 SPI interfaces,and each DAC chip can control 16 channels of digital-to-analog conversion,realize the output of 192 channels of analog signals eventually.Finally,the board is made and tested.The results show that the output analog voltage is in linear proportional relationship to the gray value,and its absolute error is about 0.010 V,which is in line with the modulation accuracy of 10 bit,1024-level voltage gray value.The driver board can realize the output of multi-channel driving signals and meet the requirements of driving control of multi-channel passive liquid crystal optical devices.