Sunlight viewable screens have been available for more than 20 years, and they're not at all expensive. The least expensive marine depth finder/fish finder cost about $100, has a 400 X 600 resolution and can be seen clearly in direct sunlight. The technique is called super-twist TFT (thin film transistor) and it actually gets brighter with increased sunlight. Essentially, the light passes through a grid, then is reflected back through the LCD display, thereby providing all the backlight needed to see the information on the screen. The current LCD displays utilize a tiny florescent light on each side of the screen, which is just about useless outdoors. Even a large, florescent, shop-light is nearly invisible in direct sunlight. You can only imagine what you get with a light that is the size of a pencil lead.

Cheers,

Gary