Colour sensor features infra-red measurement channel

The IR measurement channel enables stand-alone cameras and smartphones to adjust the colour temperature of the flash to produce higher quality photographs in both indoor and outdoor environments. Changes in the IR content of the light affect colour measurements, therefore, a passband clear (C) channel photo-diode is included to provide a direct measurement reference for mathematically subtracting unwanted residual IR energy. An integrated IR blocking filter further improves the accuracy of colour measurements by minimising IR spectral component effects.

The fifth IR channel is sensitive to IR light in a 700-1,100nm spectrum. Every light source has its own spectral fingerprint, with known proportions of UV, RGB and IR light, therefore, a system can identify the light source in the user’s vicinity by measuring the IR-to-C and Red-to-C channel ratios and applying a detection algorithm to the measurements.

By measuring the CCT and brightness of ambient light in a system, consumer electronics devices can automatically adjust the colour tones of the display for the best viewing experience under varying lighting conditions and behind attenuating dark inked glass or spectrally distorting materials.

To eliminate CCT and lux measurement errors in fast-changing lighting conditions, the TCS3490 features four independent ADCs which enable simultaneous sampling of all four channels. Featuring a radial structure, the sensor’s photodiodes create a uniform and optimised response irrespective of the angle of the incident light. The need for continuous I²C bus polling is eliminated by a level-shifter style interrupt pin, which enables the sensor to alert the applications processor when pre-set light and colour measurement thresholds are crossed. This reduces the overall system power consumption, extending the battery life.

“The consumer electronics touchscreen display is a key competitive battleground, and manufacturers can win by differentiating their brand with a more intelligent display management capability. The TCS3490 five-channel colour sensor enables manufacturers to make their display’s colours look more vibrant and engaging, as well as easier on a user’s eyes in both indoor and outdoor lighting conditions. That’s because its CCT measurements very closely match what the human eye perceives as colour and brightness,” said David Moon, Senior Product Marketing Manager, Advance Optical Solutions Division, ams.

The TCS3490, which is offered in a 2.0x2.4mm DFN package, is available now in production quantities. The sensor is priced at $1.40 each and sold in 1,000-piece quantities.