Improved Design Of Circuit System For 3D Hemet-mounted Display

As one of the three-dimensional (3D) display technique that employ the most extensive application currently ,the 3D helmet-mounted display (HMD) is a hot in display field recent years. The development of HMD is a research and practice of synthetic technology, including computer software technology, circuit technology, image source technology, mechanism and optical technology. Image source technology and drive circuit design of micro-display chip always are the key to HMD among them.According to the structure and feature of the traditional HMD, this paper proposed a design of 3D HMD drive circuit based on USB2.0 interface, PC platform, micro-display chip in technique of OLED and FPGA/CPLD primary controller. The whole drive circuit adopts the mode in which 16-bit data parallel transmit. The two pieces of 8-bit micro-display chip scanned at the same clock share the 16-bit bus as a whole and realize binocular synchronous display as a result. The design will be discussed more deeply in this paper based on previous work.Hardware circuit for data transmission controlled by FPGA/CPLD includes USB interface module, frame cache module, scan-display and registers configuration by I~2C bus module of micro-display chip. By use of USB2.0 interface chip-CY7C68013A,the problem of band width for high speed data transmission is solved. The two pieces of SRAM are used to access image data in the whole frame. ME3203 micro-display chip is chosen as display device In addition, this paper proposed a practical and improved PCB design scheme of drive circuit which optimized the function and size and further perfected the drive circuit based on previous work.The hardware program of control unit is designed by modular idea, which included slave-FIFO controller of USB interface chip, ping-pong operation of frame cache module, scan sequence of micro-display chip and PC master as well as routing of data bus and bridging logic design in practical scheme. The program is coded in Verilog HDL hardware description language. Hierarchical design(split-synthesis method) of high-level language is adopted in coding. The emulation results after synthesis meet the requirements of each chips' sequence.The software system of drive circuit, which included firmware of USB chip, USB driver and client test program, is the key to data communication between PC and drive circuit. The client test program fulfiled tasks as follows: operating USB device, reading, combin and transmiting binocular image data. The BMP image in PC was transmitted to verify hardware platform's function . The results of test demonstrate the feasibility of the design and accuracy of data communication. The drive circuit meets design requirement.