Osram Opto Semiconductors has added a very effective and low power consuming sensor to its portfolio of proximity and ambient light sensors. The company says that the compact SFH 7776 sensor registers the ambient brightness even behind dark smartphone covers and prevents unintentional responses from the touch screen during telephone calls. The company contends that this makes it even easier for smartphone designers to control the backlighting and touch functions of displays.

The digital SFH 7776 sensor contains an infrared LED (IRED) and two detectors and performs two different functions. It registers the ambient brightness in order to control the display backlighting so that it can always be easily read but consumes as little power as possible. It also deactivates the touch function on the display as soon as you hold the phone up to your ear during a phone call. The sensor sensor emits infrared light that is reflected by approaching objects, such as your ear.

The SFH 7776 sensor has a working range of up to 16 centimeters and compact size enables it use in smartphones and other mobile devices. Osram notes that thanks to the excellent sensitivity of the detector the component does not need lenses to bundle the emitted infrared light. This reportedly allows the sensor to have the small height of only 1.35 millimeters. With its black casing the sensor is virtually invisible even behind transparent phone covers. Its low power consumption is also an important factor in terms of its suitability for mobile devices – in standby mode it only needs 0.8 mA.

The very sensitive SFH 7776 has a very low detection limit of 0.002 lux (lx), and can therefore even be used behind dark casing panels. Designers can place the sensor anywhere and do not need a special translucent window.

“The SFH 777x series gives our customers a complete family of multifunctional sensors for an extremely wide range of phone covers,” said Dirk Sossenheimer, who is responsible for intelligent sensor applications at Osram Opto Semiconductors. Furthermore, the company says that the SFH 7776 is designed so that the ambient light sensor doesn´t react to short-term fluctuations in the brightness of various lamp types, caused for example by changes in the power supply frequency. This ensures that the display backlighting remains constant.

Osram claims that Crosstalk – an effect in which the emitted infrared light is reflected by the smartphone casing directly onto the receiver – is eliminated by the SFH 7776 in the component itself. For this reason, the company says that designers no longer need to provide separate optical barriers between the IRED and the detector.

Since the SFH 7776 covers the complete working range from 0 to 16 mm it would even react to direct contact (“zero distance detection”). The touch function of the display is therefore reliably deactivated even in marginal situations. “Overall, the SFH 7776 overcomes various challenges in terms of proximity and ambient light detection in the component itself, so designers can integrate the product in smartphones relatively easily," added Dirk Sossenheimer.