The result: The Edge Programmable thermostat, a “stylish, ultraslim designer device that borrows stylistically from highend photo frames,” according to Carrier. But it owes much of its thin profiles and good looks to carefully controlled backlighting, which comes courtesy of Global Lighting Technologies, Brecksville, Ohio (glthome.com). Their work includes backlighting for different areas of the display, including the LCD, overlays for characters and logos, along with backlighting for buttons and keypads. Lighting had to be bright, uniform, and with no hot spots or dark areas. It all also had to be thin, about 0.8-in. thin.

LEDs let GLT vary the brightness of the backlight. They used Microlens technology, a method of molding micro-optical elements onto the top and bottom of light guides. This is said to optimize the light-emission angle and improve the LEDs’ efficiency by more than 15%. In addition, the company can use microoptical lens arrays on the edge of the light guide to increase the normal spread of light from an LED from 90 to 120° for better uniformity.