(1) Luminozitate maximă
In the industry "standard" discussed at the end of last year, no clear characteristic requirements were given for the important performance of "maximum brightness", which is in line with GB/T1.2-2002. In the "Guidelines for Standardization Part 2: Methods for Determining Normative Technical Elements in Standards", "5.4.3 Values Determined by Suppliers" mentioned: "If diversification of products is allowed, certain products The characteristic value does not need to be stipulated (although these characteristics have a significant influence on the performance of the product)".
Because the use environment of LED display screens is very different, the illuminance (that is, the ambient brightness as ordinary people call it) is not the same, so "for most complex products, as long as the corresponding test methods are specified in the standard, the supplier provides a performance data (Product information) The list is better than the specific performance requirements given in the standard." These are all in line with international standards, but this has resulted in unrealistic comparisons in bidding, and users do not understand this. As a result, the "maximum brightness" required in many bids is often far higher than actual needs.
Therefore, it is recommended that in order to guide users to correctly understand the performance index of the "maximum brightness" of the LED display, the industry must give a guide: In some occasions, under different illuminance environments, the brightness of the LED display can reach what value. Can meet the requirements.
(2) Eroare de lungime de undă dominantă a culorii primare
Changing the primary color dominant wavelength error index from "primary color wavelength error" to "primary color dominant wavelength error" can better explain what characteristics of the LED display screen this indicator reflects. The dominant wavelength of a color is equivalent to the hue of the color observed by the human eye. It is a psychological quantity and an attribute that distinguishes colors from each other. The performance requirements specified by this industry standard, literally, users cannot understand that it is an indicator that reflects the color uniformity of LED display screens. Therefore, it is to guide users to understand this term first, and then understand this indicator? Or should we first understand and understand the LED display from the customer's point of view, and then give the user understandable and easy-to-understand performance characteristics? Just like the aforementioned GB/T1.2-2002 (Methods for Determination of Normative Technical Elements in Standards Part 2 Standardization Guidelines", one of the principles for product standard formulation is the "performance principle": "As long as possible , The requirements should be expressed by performance characteristics instead of design and description characteristics. This method leaves the greatest room for technological development." "Primary color dominant wavelength error" is such a design requirement, if it is "color uniformity" Instead, there is no LED with a limited wavelength.
Pentru utilizatori, atâta timp cât vă asigurați că culoarea afișajului LED este uniformă, indiferent de mijloacele tehnice pe care le folosiți pentru a o realiza, lăsați cât mai mult spațiu posibil pentru dezvoltarea tehnologică, ceea ce este foarte benefic pentru dezvoltarea industriei.
(3) Ciclul de funcționare
Just like the "performance principle" mentioned above, "as long as possible, requirements should be expressed by performance characteristics instead of design and description characteristics. This method leaves the greatest leeway for technological development." We believe that "duty cycle" is purely a requirement of design technology and should not be used as a performance indicator of the LED display product standard; everyone knows that there are users who care about the drive duty cycle of the display, they care It is the effect of the display screen, not the realization of our technology; why should we create this kind of technical barrier ourselves and restrict the technological development of the industry?
(4) Frecvența de reîmprospătare
Judging from the measurement method of "Standard", it seems to ignore the issues that users really care about, and it does not take into account the different drive ICs, drive circuits and methods used by various manufacturers, which makes testing difficult. For example, the full-color screen bidding of the Shenzhen Stadium, in the sample test of experts, the test of this indicator has brought many problems. "Refresh frequency" is the reciprocal of the time required for one frame of screen display. Regarding the display as a luminous light source, it is the flicker frequency of the light source. We can directly test the flicker frequency of the light source of the display screen with an instrument similar to a "light-sensitive frequency meter" to reflect this indicator. We have done this test and used an oscilloscope to measure the LED drive current waveform of any color to determine the "refresh frequency". The measured frequency is 200HZ under the white field; at low gray levels such as 3 gray levels, the measured frequency is as high as More than a dozen KHZ, but measured with a PR-650 spectrometer; whether in white field or at gray levels such as 200, 100, 50, etc., the flicker frequency of the measured light source is 200HZ.
The above points are just a brief description of the characteristics of several LED display screens. There are also many "working life", "mean time between failures" and so on encountered in bidding. No test method can be shorter It is confirmed within time whether the LED display meets the requirements of stability, reliability or life; these requirements should not be specified. The producer can make a guarantee, but it cannot replace the requirement. It is a business concept, a contract concept, not a technical concept. The industry association should have a clear statement on this, which will be very beneficial to users, producers and the entire industry.
Regarding how to guide users to correctly understand a product with a complex system such as the LED display, it is still necessary for the industry association to organize more LED display technology forums, start from the actual situation, analyze the product from the user's perspective, and guide users to correctly understand the LED display. .
