![]() How-to design LED signage and LED matrix displays (Part 1), Masashi Nogawa, EDN, July 30, 2014. ![]() Part 3 explores some of the issues which affect the image quality and reliability of LED displays, and the technologies and design techniques used to deal with them. Note: The BC signals which implement the brightness control function illustrated here are shown in the previous schematic ( Figure 4 ), highlighted with green text. Figure 5a is in a bright room while Figure 5b is in a dark room – but they both look the same to the human eye. However, the same outdoor system doesn’t need near as much light output at night.įigure 5 shows how brightness settings can change the same image, depending on ambient brightness. For example, an outdoor display system in bright daylight needs the highest light output to overcome the bright sunlight. As with adjusting the brightness on your notebook PC, it depends on the ambient brightness. However the brightness control changes all IC outputs simultaneously.īrightness control is an effective way to adjust whole display brightness. Now, all lamps can be set to have the same target digitized value.īrightness control (BC) is a similar function to dot correction adjusting output current amplitude. A best practice is to utilize visual inspection equipment which can digitize output color from a RGB lamp. Because the dot correction function adjusts output current amplitude, a calibration attempt with a dot correction causes another smaller color shift. In Part 1, we confirmed that the LED current change shifts its output light wavelength (color). įigure 4 LED display with PWM control IC including dot correction and brightness control. An example of a dot-corrected calibrated display is shown in Figure 3b. Thus, a dot correction is like a set of current-output digital-to-analog converters (DACs).
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |