Night Vision and LCD Backlight Inverters

[houseisland]

Among other duties, I support PC navigation systems on a fleet of boats.

LCD monitors were a godsend, because unlike CRT monitors, they generate very little EMI and do not interfere with compasses, radios, and other systems. And they take up very little of the highly limited space in wheelhouses.

However, I now have a problem in that most current production models of LCD monitors do not dim to black. The dimming range of backlight inverters has been greatly reduced, and the maximum reduction possible is now only to 30/40% of full brightness. For a navigation system a monitor must be dimmable (brightness and contrast) to a point where the display is not visible in daylight because the system must be used at night. If the display is too bright at night, the person at helm of the boat is blinded by the monitor. Also light from the monitor escapes from the wheelhouse windows and poses a navigation hazard for other vessels.

Monitors can be modded -- I can buy backlight inverters with a wider dimming range, but installing these voids warranties, and great care is required in matching the LCD panel and inverter properties and it is not always possible to identify the LCD panel reliably so....

True "marinized" monitors for navigation systems are obscenely expensive, and I do not need their water-proof rugged construction, since none of the boats I support have navigation equipment in open cockpits. So...

Does anyone know of any current LCD production models that dim to black?

There must be something out there. Astronomers and theater people have the same needs. But maybe they all still use CRT monitors?

[Richard1]

Having been a navigator I think I can say spend the money on marinized monitors. People spill stuff, come in from the rain wet and more. In the pilot house you need rugged equipment IMHO.

That having been said here's one option. This monitor, the NEC MultiSync LCD1980FXi, has an auto dimming feature that adapts to the brightness of the environment.

http://www.trustedreviews.com/article.aspx?art=1557

[houseisland]

Thanks Richard1.

We have been using budget LCDs for a number of years, primarily AOC LM500 models, and have never had one fail. And the company will not go to the expense of the marinized monitors. The PCs are not legally "navigation itself" but are merely "aids to navigation," and anyone skippering a boat should be able to do so with paper charts and traditional navigation equipment (ha, ha, ha..... a lot of people can't untie the boat from the dock without the computer).

I will check out the NEC model.

Thanks again.

[Platypus]

Could you source a dark clip-over filter panel for night use?

[3fingersalute]

I'm not fully understanding whay you are asking; wouldn't dimming to entire blackness be the same as just turning it off?

[houseisland]

Turning the brightness and contrast down to their lowest settings so that the monitor appears black in daylight still leaves a faint display which is visible in total darkness.

Even the power and hard drive LEDs are too bright and if the PC is not in a cabinet they are usually taped over with electrical tape - red tape works quite well.

The filter system works to a point in combination with other things. Navigation programs such as Nobeltec Visual Navigation Suite, Maptech Offshore Navigator, and Maxsea have night display modes. There is a freeware program call Dark Adapted which was designed for astronomers and which allows the tweaking of the display's gamma settings. But it is all not as good or as convenient as using the brightness and contrast controls. Some people have taken to putting a black plastic garbage bag over the monitor, an inelegant but practical solution.