Avago Technologies has announced a color controller with an integrated color photosensor for backlighting LCDs, touted to be the industry's first such product. According to the company, the new ADJD-J823 enables more accurate and consistent RGB LED backlighting and richer colors than conventional technology. This solution is suitable for use in digital cameras, cell phones, PDAs, portable DVD players and display screens measuring 7 inches diagonal or smaller.
The device has a small footprint and low profile that allows it to easily fit into portable LCD devices where board space is limited, Avago said. The 5-by-5-by-0.75mm illumination and color management (ICM) device operates at voltages as low as 2.5V.
The new device is a CMOS mixed-signal IC with integrated RGB photosensors designed to be the closed loop optical feedback device of an RGB LED-based backlighting system. It also has a wide gain control and uses an algorithm to automatically select the optimum gain.
A typical system consists of an array of RGB LEDs, LED drivers and the color controller. The device samples the light output from the RGB LED array, processes the color information and adjusts the light output from the RGB LEDs until the target color is achieved. To do this, the device integrates an RGB photosensor array, an ADC front-end, a color data processing logic core and a high-resolution 12bit PWM output generator. By employing a feedback system and the color controller, the light output produced by the LED array maintains its color over time and temperature.
"By integrating the sensor and controller into one package, we are expanding the benefits of color management to the growing array of applications using color LCD screens in smaller consumer electronics," said Lee Soo Ghee, vice president and general manager for Avago's Optoelectronic Products Division.
Avago said the use of LED backlighting with the company's ICM control in LCD TVs has been proven to offer 25 percent richer colors than conventional cold cathode fluorescent lamp (CCFL) backlighting. In addition, LED backlighting totally eliminates the traces of mercury found in CCFLs to meet European Union RoHS mandates, the company said.
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