Min Light in Lux for the Clear View of LCD Screen

Sounds like a good question for the manufacturer of your LCD screens. Your minimum level will depend on the type of activity that is to take place. For instance, will the occupants need to read or write, take notes, or just manage to get around without tripping over each other?

As to the maximum, the LCD manufacturer only supplies a fixed amount of backlighting lux and he will be able to guide your design. The rest of us would be making assumptions that may be invalid because we don't know anything about what kind of LCD you have.

Good luck with your quest.

well the LCD is used in NOC room and hopefully u knw how it works in NOC room i aslo need to know is 500 lux of illumination is good enough for the room of area 34 sq meter as my NOC room is 6.5x5.5 meters

I don't know what a NOC room is, but I know about lighting and displays.

The luminance (commonly called brightness) of an LCD screen is not measured in Lux, it is measured in candelas per square meter (cd/m²) which is sometimes referred to as 'nits'.

Lux is a measure of illumination, which is the amount of light falling on a surface; nits (or more properly, cd/m²) is a measure of luminance, or light coming from a surface, either by emission or reflection. [Nits is an archaic term and its use is discouraged, though people are still using it.]

There is no direct correlation between Lux and Nits for an LCD because the LCD is not a lambertian emitter, i.e., it does not emit light equally in all directions. You'll need to get a photometer and measure the LCD screen luminance to see how many cd/m² are being emitted.

Typically a display that is used in a dark room needs to be dimmable to around 1 to 5 cd/m². (In an aircraft cockpit, at night, LCDs are often dimmed to 0.2 cd/m².)

Conversely, a display that is used outdoors needs to achieve between 500 and 1000 cd/m² to be just barely readable in sunlight. In an office environment, the display might only need to have a luminance of 50 to 100 cd/m².

So those are the extreme limits for most displays. You'll need to decide how bright your NOC room is, and then decide how bright your LCD screens need to be.

The room illumination should be lower than the screen luminance. Once you get a photometer, aim it at white pieces of paper taped to the walls and floor of your NOC room. You'll want the luminance of the white paper to average less than the luminance of your screens, perhaps half the luminance.

The best thing, really, is to hire an illumination engineer on contract. He (or she) will give you advice and save you a lot of problems, and probably save you a lot of money if the system you build is wrong and then needs to be replaced. There are a lot of unknowns in your situation that ought to be looked at by a pro, rather than you just using the very simplistic information I gave you above.

NOC = Network Operations Center.

It's like Valhalla for computer nerds...