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Add Intelligence To Touch Interfaces With Fully Integrated Proximity & Ambient Light Sensors

Smartphone Sensors

The process of the digitalisation of our environment and the connection of nearly everything to the Internet creates tons of new possibilities. Possibilities which need intelligent user interfaces and control. Buttons tend to vanish and are often replaced by touch screens and gesture control.

The Need For Sensors

Those modern control interfaces and displays need sensors in order to adapt to their surroundings. There are two main parameters which need to be observed. The first is the proximity to other objects in order to switch the display on and off as well as to adapt the displayed functions. Modern displays are usually also equipped with ambient light sensing capabilities in order to tune the display brightness to the perfect balance of energy saving and readability.

While proximity and ambient light sensors are used individually in many different applications there is a vast variety of use cases which requires both. Good examples are smartphones which use proximity sensors to switch of the display during calls to prevent unwanted interaction with the touch interface. At the same time the devices use ambient light sensors to adjust the display brightness to a comfortable level to your eyes and to save energy in low light environments.

Nearly every modern device equipped with a touch screen can benefit from both sensor types (e.g. tablets, smartwatches, touch displays in cars, cameras).

Vishay’s Fully Integrated Proximity & Ambient Light Sensors

In order to be able to support such applications in the best way Vishay has introduced several products integrating proximity and ambient light sensors in one part (VCNL4010, VCNL4020, and VCNL4020X01).

Those devices obtain the infrared emitter and photo detector for proximity sensing. In addition an ambient light sensor, a signal processing IC and I2C communication interface are integrated. The VCNL family offers full 16-bit resolution for both the proximity and ambient features as well as user-defined interrupt levels along with multiple packaging options.

Vishay VCNL Family
Fully integrated proximity and ambient light sensor solutions from Vishay (image: Vishay)

As the window design and sensor placement is already taken care of and the need for mechanical cross-talk barriers is eliminated the design process is greatly simplified by Vishay. Each sensor is further equipped with standard I2C communication and an interrupt function (reducing power consumption through elimination of polling traffic between the sensor and microcontroller).

Integrating The Sensors In Your Design

While proximity and ambient light sensing for consumer goods might seem pretty straight forward especially with the VCNL products there are still some basic challenges to overcome. Among them is the placement of the sensor in order to achieve the best results (see below).

Proximity Sensor Placement
The ideal window sizes for the VCNL4020X01/VCNL4020/VCNL3020 based on the depth of the sensor are shown in the table above. Different shapes and smaller sizes are possible but performance may be impacted. (image: Vishay)

In addition, finding the best balance of measurement parameters and energy consumption is key to implement the features of the sensors without sacrificing battery life (use Vishay’s Optical Sensor Current Estimator here to try different scenarios).

In order to choose the best part for your device it is further recommended to utilise the Vishay Sensor Starter Kit to select the best components and to evaluate the different sensors. The kit comes with software, USB I2C interface and the VCNL4020 board (learn more in this video here). To evaluate all sensors you can choose additional VCNL add-on boards.

For Vishay hardware, support and questions feel free to contact us here

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