Research on Timing of Automotive LED Dimming and Color Mixing Downlight and LED Large Display Screen

It can be predicted that the development of LED may need to go through three stages: cultivation stage, popularization stage and differentiation stage. The cultivation stage has passed, and the time point should be from 2008 to 2012; The popularization stage takes 2012 as the time point and is coming soon. The popularization storm will perplex manufacturers at the end of the popularization stage. How to highlight homogenization? We believe that bringing LED lighting into smart home and smart commercial lighting is a good way out.

Dimming and toning downlight was born for this purpose. We integrate the "dimming and toning" technology into the downlight in order to give more added value to the product. We have made an in-depth analysis of LED dimming and color matching, that is, it is a product, which should not only highlight the key points: dimming (brightness) and color matching (color temperature can change continuously, from 3000K to 6000K), but also have good man-machine interface and bus expansion ability (so as to be included in the general interface of intelligent home).

As a set of system, dimming and color matching scheme is composed of "digital controller" and "controlled dimming and color matching downlight group". The first thing is to design a set of transmission protocol to ensure that the user's operation can be finally accepted and responded by the downlight. In the process, we found that the LED dimming and color mixing downlight is different from the current LED display and other timing protocols. Their relationship is just like the difference between FTP and UTP.

For example, the key point of LED lighting requirements is: the user's operation can be effectively and reliably reflected, which is different from the requirements of LED large screen display. The signal of LED lighting must first ensure reliability and avoid bit error as much as possible, and the LED display can continue after allowing bit error and frame loss;

Secondly, the data flow transmitted by LED lighting is much shorter, because it does not have a large amount of content like the display screen. Therefore, there are fewer data packets, which can adapt to a longer transmission distance, and it is possible to control the transmission through wireless means (such as GPRS, WiFi, ZigBee, power line transmission, etc. of smart home);

Third, the data of LED lighting is sudden and time delay is allowed. In other words, compared with LED point light source landscape lighting and large screen display, the data transmission of LED lighting is sudden rather than sustainable, and it is idle most of the time. Only when the user operates the LED, the controlled lamp needs to respond. The allowable delay mentioned here means that most users have an acceptable delay of 100 milliseconds for LED lighting control.

Fourth, it is necessary to suppress surge through timing. Therefore, we can effectively suppress the impact on the power grid when the dimming and color mixing downlights are suddenly turned on and off through certain software operations (such as sequential delay).

Since timing is so important, we can simply design a timing to explain some characteristics of LED dimming and color mixing downlight. For example, in the hardware of downlight receiving end, we can build a single chip microcomputer, which is used to receive data packets transmitted from the transmitter.