Analysis of the main performance indexes of LED display screen

The beginning of 1998, after five years, in the LED-display.cnLEDw.com/ >LED display Committee (now China Guangxie branch LED display) organization efforts, "the industry standard LED display test method" (hereinafter referred to as the "standard") will be issued. So as to correctly guide the user to understand the performance indicators of the LED display, it is very important to regulate the LED display market.

In order to better implement the standard, the following suggestions are put forward.

1 maximum brightness

At the end of last year the industry "standard", did not give a clear feature of this important performance for maximum brightness, which is consistent with the GB/T1.2-2002. In the "directives for Standardization - Part second: Standard normative technical elements content determination method of" 5.4.3 "by the determined value" mentioned: "if allow product diversification, some characteristics of the value of the products can not make provisions (although these characteristics on the performance of the product has obvious effect)". Because of the use of LED display environment vary widely, illumination (which is generally known as the brightness of the environment) is not the same, so for the most complex products, as long as the criteria specified in the corresponding test methods, provide a performance data by the supplier (product information) a list of specific requirements of better performance than the standard". These are in line with international standards, but it also resulted in the bid unrealistic users to compare with each other, and do not understand, resulting in many tender requirements of the "maximum brightness" is often far higher than the actual need. Therefore, in order to guide the user to correctly understand the recommendations of LED display "the maximum brightness of the performance, it is necessary to provide a guidance for Industry: in some occasions, in different light environments, the brightness of the LED display panel to what values can meet the requirements.

2 color main wavelength error

Will color the main wavelength error index, from the "wavelength error" to "the main wavelength error of primary colors, more to the index reflects the LED display a characteristic of what. The color of the main wavelength is equivalent to the color of the human eye to observe the color, is a psychological quantity, is the color of a distinction between each attribute. The performance requirements of this industry standard, literally, the user is unable to understand that it is an indicator to reflect the color uniformity of LED display. Therefore, is to guide the user to understand the term first, and then understand the index? First, from the customer's point of view to understand and understand the LED display, and then give the user can understand the easy to understand the performance characteristics? As mentioned earlier, GB/T1.22002 (which means "the content of normative technical elements of standardization work for the second part of the standard of product standards for a principle that" performance principle ":" as long as possible, performance requirements shall be expressed without design and describe the characteristics of expression, this approach to technology have the largest room for development". "Primary wavelength error" is such a design requirement, if the "color uniformity" instead, there is no limit to what wavelength LED. For users, as long as you promise to the LED display color is uniform, regardless of what you are using technology to achieve the greatest possible, leave room for the development of technology, thus greatly beneficial to the development of the industry.

3 duty cycle

Like the "performance" principle "as long as possible, performance requirements shall be expressed without design and describe the characteristics of expression, this approach to technology development have the largest room". We believe that the "duty" is a design technique, should not be a performance index for the LED display product standards; everyone is very clear, which users will care about the display driver duty cycle, they care about is the display effect, and not our technology; why should we own the manufacturing technical barriers to limit the industry's technological development?

4 refresh frequency

From "measurement standard" point of view, seems to ignore the real concerns of users, it is also not very good considering the various manufacturers for driving IC, driving circuit and the way of a test, causing difficulties. For example, Shenzhen stadium full color tender, in the sample testing experts in this test will bring many problems. "Refresh frequency" a picture of the time required to display the countdown, the display as a light source, which is the flashing frequency of the light source. We can use a kind of "light sense frequency meter" instrument to directly test the light source flicker frequency of the display screen to reflect the index. We have done this test using oscilloscope to measure any color LED driving current waveform to determine the "Refresh" in the white field measured under 200HZ; in the 3 gray level and low gray level, by measuring the frequency of up to ten KHZ, and using PR-650 spectrometer; whether in white or in the field. 200, 100, 50 level gray level, the measured light blinking frequency was 200HZ.

The above is just a simple explanation for several characteristics of LED display, there are a lot of bidding in "working life" and "MTBF" and so on, not a test method to confirm that LED display is in accordance with the requirements of stability, reliability and life in a relatively short period of time should not be required; these requirements. The producer can guarantee, but can not replace the requirements, it is a business concept, the concept of the contract, rather than technology