FQA

LED display is composed of the array of LED devices used to display text, text, graphics, images, animation, market, as well as a variety of television, video, live events and the like.  LED display screen is a new type of information and communication media; It is a collection of electronic, optical, communication, computer, network, structure, civil engineering and other disciplines.LED display is kind of customized products due to different specifications and sizes.

Grey level: A calibrated sequence of grey tones, ranging from black to white. In remote sensing, electromagnetic radiation falling on a photosensitive receiver generates an electrical current proportional to the intensity of the radiation. The receiver is usually tuned to specific wavelength bands and the signal from each receiver is amplified and its intensity classified into different levels, usually 0 (black) to 256. These are the digital numbers of each of the pixel units that together make up a remotely sensed frame. In multi-spectral scanning systems, the digital numbers are classified into grey-scale bands, of which there are usually 10 to 12, but up to 256 shades of grey (brightness) may be used. 

The color and brightness emitted by an LED are determined by the chemical composition and construction. Single-color (monochrome) displays are made up of one color of LEDs, whereas full-color displays contain LEDs that emit red, green and blue light. The color efficiency of the human eye has different sensitivity to different colors, and therefore perceives the brightness of each color differently. 

The number of LEDs alone does not determine display brightness. The design, quality, brightness, lens and viewing angle of the LEDs, as well as the drive method and contrast of the module, determine the overall brightness of a display. In fact, using more LED’s per unit area creates more hear and therefore requires more cooling.

Pixel Pitch is the distance between neighboring pixels which calculated by mm. 

Pixel Density is the quantity of pixels per square meter. 
Pixel Configuration is the description of the consistence of a pixel. For example, we use 1 red lamp, 1 green lamp, 1 blue lamp to compose a pixel, the pixel configuration is 1R1G1B or SMD 3 in 1. 

The operational lifetime of an LED Display is determined by the lifetime of the LEDs. LED Manufacturers estimate the LED lifetime to be 100,000 hours under certain operating conditions. The lifetime is decided when the brightness has decreased to 50% of original brightness.

Three primary factors determine LED lifetime:
Manufacturing process of the LED
Driving (powering) method of the LED
Temperatures present at the LED die during operation

LED thermal management is vitally important to maintaining LED lifetime. Increasing the power through an LED increases brightness but reduces its lifetime due to increased heat generation. Increased exposure to higher temperature also shortens the lifetime. LED thermal management can only be done through the LED lead frame by conducting the heat to a Printed Circuit Board (PCB) and by allowing airflow to cool the LED lead frame.

LED Display components must be designed to handle a wide range of outdoor environmental factors, such as temperature and humidity. All components must be coated to protect from possible corrosion.

Ingress Protection (IP) is a European rating that describes the degree of protection provided by an enclosure of electrical equipment. The rating system consists of the letters IP followed by two numbers:
The first number indicates the degree of protection against solid foreign object ingress.
The second number indicates the degree of protection against liquid ingress. 

According to this system an IP65 enclosure will not allow the ingress of dust and is protected against jets of water from any direction. IP65 enclosures are ideal therefore for use in wet and wash-down environments for example food preparation areas.