Gray-scale Modulation Of Dynamic Infrared Image Simulation System Of The Dmd Chip

The application of simulation technology in various fields has attracted the attention from more and more countries internationally. Related to infrared technology, infrared simulation can be applied to optimization, performance evaluation of infrared systems (i.e. infrared lead, FLIR, Forward Looking Infra-Red system), and the evaluation of search-track algorithm.First the theory and design of the infrared dynamic imaging simulation system is introduced by this dissertation. By comparing of several infrared image generation methods, using DMD (Digital Micromirror Device) chip as infrared modulation device to develop dynamic infrared image simulation seems to be a feasible approach. For the system that using DMD chips for infrared simulation, grayscale modulation with DMD is the core technology. Several grayscale modulation methods are introduced, like amplitude control, spatial grayscale modulation, and timing grayscale modulation, etc. After comparing above methods for DMD chip, PWM (Pulse Width Modulation) is chosen to modulate the grayscale signal for the image.There are two methods to implement PWM, pulse width counting method, and pulse gated method. Pulse width counting method is to compare the grayscale signal from binary image that stored in the latch, with the value in the counter. The counter and comparator control the duty cycle of the pulse in order to modulate the grayscale signal. Based on the method mentioned above, two plans that use reversible counter and up-counter has been proposed. The plan of using reversible counter to modulate grayscale has been applied to the field emission display technique. This plan will be used for DMD chip grayscale modulation in this thesis. Another plan of using up-counter is also provided. It is individually verified by simulation for its feasibility. Pulse gated method is to split the time to several binary time in one pulse cycle. In the grayscale modulation, every bit in the binary image corresponds to different binary time. Whether each time period could be selected depends on each value in the binary grayscale signal. Specific to this method, it is individually verified by simulation for its feasibility by using 3 new designs including sequential signal generator, shift register, and multiplexer. For 4-bit and 8-bit grayscales, circuit is designed for each method, how to improve when expand grayscale level is explained, and the advantage and disadvantage are shown for all 5 method after comparison.Finally, an improved algorithm for grayscale signal modulation is utilized in this thesis. It will combine the PWM and FRC (Frame Rate Control) together to improve the grayscale modulation system.