Research On Digital Signals Processing System Of Automatic Lensmeter

Based on the principle of the Lensmeter and the technology of CCD, step-motor auto-focusing and Digital System Processor(DSP), a novel principle and realization of the Automatic Lensmeter is proposed in this article. Firstly, the image signal is generated from LEDS which are under control of the DSP. Then, the high-resolution linear CCD obtains image signal. At last, signal sampling, signal processing, and controlling the step-motor to focalize are carried out by DSP. And optical parameters of the spectacles are obtained.In the article, the background, definition and classification of the Lensmeter are discussed, and the principle of the current Lensmeter is analysed, based on which the novel principle of the Automatic Lensmeter is proposed. The design of the whole system is followed, including the design of the lamp-house module, the design of the CCD module and the design of the auto-focusing module. The software and hardware research environment is given. The generation of the optical signal and the signal processing are discussed in detail. Based on the serial communication, the person to computer interface of this system is developed, and the interface on the PC is realized. In view of the demand for the real time controlling and data processing, TMS320F2812 DSP is chosen as the system CPU. This DSP has low power consumption, high-performance speed, and abundant on-chip resources. Therefore, the step-motor is driven directly without any additional circuit. Such characteristics not only reduce the cost and the difficulties of the system research, but also save the time of the research development.