With quickly advance of the computer, microelectronics and photonics technologies, LED display panel becomes a new
electronic advertising media. It can be used to show any information whatever characters or graphics. Most LED display
panels are built of many Light-Emitting Diodes arranged in a matrix form. The display has many advantages such as low
power, low cost, long life and high definition. Because the display panel is asked to show rich color, the LED display
panel's driving system becomes very complex. The design methodology of LED display panel's driver becomes more
and more important to meet the market requirements.
Cost is always the most important issue in public market domain. In this paper, we report a design methodology of LED
display panel's driver based on the microprocessor control unit (MCU) system and LED display controller IC, HT1632C,
to control three colors, RGB, color LED display panel and the modular panel size is 24*16 in matrix form. The
HT1632C is a memory mapping LED display controller, it can be used on many applications, such as digital clock,
thermometer, counter, voltmeter or other instrumentation readouts. Three pieces of HT1632C are used to drive a 24*16
RGB LED display panel, in our design case. Each HT163C chip is used to control one of the R, G and B color. As the
drive mode is driven in DC mode, the RGB display panel can create and totally of seven colors under the control of
MCU. The MCU generates the control signal to drive HT1632C. In this study, the software design methodology is
adopted with dynamic display principle. When the scan frequency is 60Hz, LED display panel will get the clear picture
and be able to display seven colors.
Saving energy, White-light LED plays a main role in solid state lighting system. Find the best energy saving driven
solution is the engineer endless hard work. Besides DC and AC driving, LED using Pulse Width Modulation (PWM)
operation is also a valuable research topic. The most important issue for this work is to find the drive frequency and duty
for achieving both energy saving and better feeling on the human vision sensation. In this paper, psychophysics of
human vision response to the lighting effect, including Persistence of vision, Bloch's Law, Broca-Sulzer Law,
Ferry-Porter Law, Talbot-Plateau Law, and Contrast Sensitivity, will be discussed and analyzed.
From the human vision system, we found that there are three factors: the flash sensitivity, the illumination intensity and
the background environment illumination, that are used to decide the frequency and duty of the PWM driving method. A
set of controllable LED lamps with adjustable frequency and duty is fitted inside a non-closed box is constructed for this
When the background environment illumination intensity is high, the variation of the flash sensitivity and illumination
intensity is not easy to observe. Increasing PWM frequency will eliminate flash sensitivity. When the duty is over 70%,
the vision sensitivity is saturated. For warning purpose, the better frequency range is between 7Hz to 15Hz and the duty
cycle can be lower down to 70%. For general lighting, the better frequency range is between 200Hz to 1000Hz and the
duty cycle can also be lower down to 70%.