Optimise display performance in mobile devices with optical sensor

May 13, 2014 // By Graham Prophet
ams’ integrated colour sensor drives intelligent display management in smartphones and tablets; the TMD3782 digital sensor is intended for use in mobile devices and combines ambient light, colour and proximity sensing.

Positioned as the first integrated ambient light, colour (RGB) and proximity sensor that is optimised for operation behind dark glass to drive intelligent display adaption in mobile devices, the TMD3782 optical module is suited for smartphones and tablets. The sensor integrated in the TMD3782 provides ambient light intensity (lux) and colour measurement enabling mobile devices to automatically adjust their display’s colour and brightness for the best viewing experience and power savings.

High-resolution displays on mobile devices must operate in a wide range of light sources, including fluorescent, incandescent and sunlight. The TMD3782 on-chip filters minimise the effects of ultra-violet and IR light and enable its photopic response thus improving the overall accuracy of light and colour sensing. The device is able to sense light in a similar manner to the human eye, enabling more sophisticated control of the display brightness and colour.

The TMD3782 packs the ambient light, colour and proximity sensor, IR LED and optical lenses in a 3.9 x 2.4 x 1.4mm module. The sensor’s integrated proximity sensor can be used to simplify a product’s user interface, for instance, supporting intelligent on/off control of smartphone touchscreens. The device’s integrated proximity sensor also allows tablets to eliminate false ambient light sensing measurements by detecting when the user’s hand or finger is blocking light from reaching the sensor. The proximity detection is factory-calibrated to a distance of 100 mm, eliminating the need for OEMs to perform production-line calibration, and simplifying end-product manufacturing.

The TMD3782 sensor’s photodiodes have a radial structure to create a uniform and optimised angular response when mounted under the 360° module lens. The sensor also provides a 45 degree field of view for a broader and more accurate measurement of the lighting environment. An interrupt capability enables the sensor to alert the applications processor when pre-set light and color measurement thresholds are crossed, eliminating the need for continuous polling and reducing overall system power requirements and hence