Optical sensor for measuring ambient light behind smartphone OLED screens

    Ams has announced the TCS3701, an RGB light sensor and infrared proximity sensor IC that accurately measures ambient light intensity behind OLED screens. This feature caters to today's industry design trends to maximize the display area of your smartphone by eliminating the front bezel, which is typically where the ambient light/proximity sensors are located.

     By developing this "behind the OLED screen" ambient light/proximity sensor, Ams enables smartphone manufacturers to achieve the highest display area to body size ratio while retaining key touch screen disabling and automatic display brightness/color adjustment functions, which require an RGB/ infrared light sensor.

     Although the TCS3701 is limited in its operation behind the light-emitting OLED display, it can still sense ambient light that passes through the display and is superimposed on the light emitted by the display pixels directly above the sensor. Ams has developed unique algorithms that accurately detect ambient light levels without the need to know the brightness of the display pixels above the sensor.

     Light transmission through an OLED screen is limited by its transmittance, but the TCS3701's ultra-high sensitivity to light shows that it can still make accurate light measurements in all lighting conditions. The TCS3701 comes in a 2.0mm x 2.5mm x 0.5mm OQFN compact package that can be placed behind the OLED screen of a smartphone. It gives smartphone designers the flexibility to install infrared emitters to support proximity sensing at the optimal front position. Crosstalk compensation algorithm provides reliable proximity sensing performance.

     David Moon, senior marketing Manager at Ams, said: "Today, smartphone Oems are striving to maximize the screen proportion of their products and minimize the bezel area on the display surface. The TCS3701 gives phone designers the ability to take this trend to the next level, potentially eliminating bezels altogether. This is because the TCS3701 can operate behind an OLED display, a breakthrough achieved by excellent device sensitivity and sophisticated measurement algorithms to compensate for optical distortion caused by an OLED display."