Miniaturization and Battery Capacity in Wireless Earbuds and other Wearable Devices

ROHM has developed a compact 2.0mm × 1.0mm proximity sensor, the RPR-0720, optimized for applications requiring attachment/detachment and proximity detection.

As the use of IoT continues to grow, sensor devices that play a critical role are requiring greater miniaturization and functionality. ROHM offers a lineup of proximity sensors that combine light emitting and receiving elements in a single package, providing unmatched versatility that has led to widespread adoption in a range of applications, from mobile devices to industrial equipment. Particularly for wearable devices, in response to the growing demand for small proximity sensors that can support improved designs and an increase in the number of parts resulting from higher functionality, ROHM developed a compact proximity sensor that integrates a VCSEL and sensor IC.

The RPR-0720 is an optical sensor module that adopts a VCSEL featuring higher directivity than LEDs as the light emitting element and a sensor IC for the light receiving element. Compact size is achieved by optimizing the module structure using in-house chips, reducing area by approximately 78% compared to conventional products. At the same time, the wide input voltage range (2.7V to 4.5V) of the built-in VCSEL eliminates the need for a peripheral voltage booster circuit (i.e. consisting of a power supply IC, three capacitors, and one inductor) when using a Li-ion battery, contributing to greater space savings that leads to smaller applications and increased battery capacity. This makes it suitable not only for sensing attachment/detachment, but also for detecting various conditions in a wide range of applications.

Going forward, ROHM will continue to develop sensing products that meet customer needs by combining original light receiving and emitting elements to further improve energy savings and convenience.

 

Application Examples
Suitable for a wide range of applications that use light reflection to detect conditions.
◆ Attachment/detachment detection of wireless ear buds, smart watches, gaming console controllers, VR headsets, and the like
◆ Paper detection in printers, copiers, shredders, and other office automation devices
◆ E-cigarette cartridge/liquid detection
◆ Detecting various conditions in smartphones and laptops

Evaluation Board
ROHM also offers an evaluation board for the compact RPR-0720 proximity sensor (RPR-0720-EVK).
A user guide for the evaluation board is available on ROHM’s website.
https://www.rohm.com/products/optical-sensors/reflective-type-photosensors/rpr-0720-product#evaluationBoard

Terminology
VCSEL
Short for Vertical Cavity Surface Emitting Laser, a type of laser diode that can emit light directly from the surface. Although conventionally used for communication, it is increasingly being adopted in recent years as a light source for the optical block in sensing systems.

Featured Products

Ultra-compact and short-range detection ideal for wearables
Ultra-Compact Optical Proximity Sensor
RPR-0720 (PDF:1.4MB)

Source: http://www.rohm.com