KEYWORDS: Light emitting diodes, Clocks, LED displays, Data conversion, Binary data, Data modeling, Optoelectronic devices, Digital signal processing, RGB color model, Switches
Designed a three-channel LED driver, realized the single-wire transmission of cascade signal between the drive IC of LED. Including the MCU digital interface, date register, clock synchronization, PWM grayscale adjustment circuit, as well as high voltage driver circuit for LED, etc… The driver control LED displaying 256 gray. Chip will generate synchronous sampling clock signals according to the received serial signals, when 24 bits dates have been received, the output pin begins to transport the dates followed-up which are automotive shaped to the input of the next chip. When the date receiving becomes low level that represent RESET, the red, green and blue channels will export different signals based on different input dates. Through the external MCU, it is realized the Separate luminance, and by connecting chips in series it achieved the control of outdoor big screen’ colorful display. The automatic shaping forward technique makes the number of chips cascading immune to the limitations of signal transmission, but only limited by the refresh speed.
Light-emitting diode (LED) is a liquid cold source light source that rapidly develops in recent years. The merits of high brightness efficiency, long duration, high credibility and no pollution make it satisfy our demands for consumption and natural life, and gradually replace the traditional lamp-house-incandescent light and fluorescent light. However, because of the high cost and unstable drive circuit, the application range is restricted. To popularize the applications of the LED, we focus on improving the LED driver circuit to change this phenomenon. Basing on the traditional LED drive circuit, we adopt pre-setup constant current model and introduce pulse width modulation (PWM) control method to realize adjustable 256 level-grays display. In this paper, basing on human visual characteristics and the traditional PWM control method, we propose a new PWM control timing clock to alter the duty cycle of PWM signal to realize the simple gamma correction. Consequently, the brightness can accord with our visual characteristics.
Infrared focal plane array (IRFPA) is a key component in infrared system and thermal imaging devices, widely applied in military and civilian fields, with a huge market potential and prospects. IRFPA readout circuit technology and test technology in its research occupies an important position, related to the ability to accurately and efficiently obtain the IRFPA signal and the ability of IRFPA devices for accurate performance evaluation. This paper uses an IRFPA point-by-point bias calibration, through a series of accurate timing control signals to read and save the calibration data and external input, effectively increases the point-by-point bias control accuracy, and finally improves the quality of the output image.
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