ams: light sensor with 50/60Hz flicker detect eliminates banding
ams introduces a new color (RGB), proximity and flicker detection sensor, the TCS3707, which enables a mobile phone camera to take clean, unblemished photo-graphs in artificial lighting scenes.
When equipped with a TCS3707, a mobile phone’s camera may be used in any conditions, including under artificial light sources such as fluorescent lights or street lamps, without suffering from banding or other image artefacts generated by the invisible flickering of AC powered lighting.
The TCS3707’s ultra-high sensitive RGB, Clear, Wideband channels enable accurate measurements of the color and intensity of ambient light across a wide range of lighting conditions. This enables mobile phone makers to deploy sophisticated display brightness and color management schemes, and to implement camera and flash color balancing.
The device’s flicker detection engine can detect the flickering of any artificial light source operating from 50Hz or 60Hz alternating current cycles. Flicker produces banding and other artefacts in pictures taken by an image sensor with a rolling shutter. The effect is produced when the flickering light turns on or off while the shutter is in operation.
The TCS3707’s flicker detection capability allows the camera controller to synchronize the shutter with the ‘On’ part of the AC cycle. The sensor can also supply flicker measurements to the mobile phone’s applications processor to support flicker cancellation firmware at frequencies other than50/60Hz by using the internal FIFO on the device.
The TCS3707 proximity sensor embeds IR cross-talk rejection and, when paired with an IR emitter, produces reliable proximity detection. The TCS3707 is supplied in a 2.0 x 2.5 x 0.5mm OQFN package.