Many terminal customers often pay attention to various parameter indicators when choosing industrial LCD screens, and the brightness of the screen is the most important concern for many terminal customers. However, many manufacturers have different brightness units for brightness parameter information. So what do they all mean? How to convert them? What is the reference value for the performance of industrial display screens?
For display devices, brightness is a crucial performance metric that determines whether the LCD screen can be clearly visible in direct sunlight. And brightness is measured in candela per square meter (cd/m2) or nit. Just like the power of a car engine is expressed in "horsepower", so is the Nit. The significance it represents is that the brightness of a display screen is equivalent to the brightness of how many candles. The amount of light on a 300 nit desktop monitor is equivalent to the brightness of 300 candles in a space of 1 square meter. The 1500 nit outdoor display screen is equivalent to the illumination of 1500 candles.
Furthermore, Knight is not the same as ANSI lumens (a universal specification in forward projection solutions). 1 lumen represents the amount of light reflected by a candle per square meter at a constant distance. Reflected light can be measured using lumens, while direct light can be measured using nits. This is why projectors typically use lumens for brightness, while displays (including rear projectors) use Nit. Sometimes, projection installation is calculated using foot lamberts (FL), which is equivalent to a brightness of 1 lumen per square meter, with the aim of producing higher perceived brightness screen reflections in brighter rooms. 1 nit is equivalent to approximately 0.292FL.
Returning to the display screen, in order to measure the brightness of the display screen, it is necessary to display some images on the screen. Normally, when the screen displays a fully white screen, brightness measurements are taken from edge to edge and from top to bottom. For displays such as LCD screens that require a backlight source, conducting a full white measurement can determine the maximum light output that the display can achieve. Although it is unlikely that users will display a fully white image on the screen, this value represents the highest brightness that the display screen can achieve.
For self luminescent display devices (such as plasma, OLED, or LED screens), brightness calculation is more difficult. Because each pixel is directly addressed (and turned on or off based on the content pointing to that pixel), the brightness of each pixel will change as the power of the driving pixel is shared among all pixels. For example, when displaying a fully white screen, the measured brightness will be lower than the brightness of a small white square displayed in the middle of the screen. These two situations represent two common indicators, one is standard brightness measurement (i.e. typical value), and the other is peak brightness measurement (i.e. peak value).