New LED Device Controls Color, Brightness With 1 Circuit System

Aug 22, 2014
Mami Akasaka, Nikkei Technology Online
The newly-developed LED devices. The "GW6TGBJC50C" (left) and "GW6NGWJCS0C." (image courtesy of Sharp)
The newly-developed LED devices. The "GW6TGBJC50C" (left) and "GW6NGWJCS0C." (image courtesy of Sharp)
[Click to enlarge image]

Sharp Corp developed two kinds of LED devices that adjust color in accordance with brightness by using only one circuit system.

The devices, "GW6NGWJCS0C" and "GW6TGBJC50C," are targeted at lighting apparatuses such as downlights and spotlights.

Conventional light sources such as incandescent lamps change their color temperatures (colors) when their illuminances (brightnesses) are changed. It is believed that humans find comfort in a certain range that is defined by the relationship between illuminance and color temperature (when illuminance and brightness simultaneously change in a certain way). And LED devices are now increasingly being required to have such characteristics.

The new LED devices developed by Sharp have two light sources that have different colors and are made by sealing an LED chip with two kinds of fluorescent plastics. By changing the output of each light source and mixing colors, the color temperature can be adjusted between 2,000 and 3,000K.

In general, two circuit systems are necessary to control the outputs of two light sources. However, Sharp enabled to do it in accordance with brightness control only with one circuit system by applying its own current control technology. As a result, it became possible to simplify the circuit design of LED lamps and easily embed them in lighting apparatuses.

Moreover, with a packaging technology called "Zenigata" (shape of a coin), it is possible to realize an LED optical design that has a small light source area and reduces the unevennesses of brightness and color. Furthermore, because of the high color rendering index (Ra) of 92-94, it is possible to reproduce the natural color of an object on which light is applied.

Sharp will start to deliver samples Aug 22, 2014, and begin volume production in September. The prices of the samples of the GW6NGWJCS0C (input power: about 12W) and GW6TGBJC50C (input power: about 35W) are ¥1,500 and 3,600 (approx US$14.4 and 33.7, including tax), respectively.