Steering the Metaverse via Wearables with Optical Finger Navigation Technology

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The immersion of users residing in the metaverse requires the combination of physical hardware and software contents of AR / VR to produce a feeling of real engagement with the simulated world. Through years of experience-vision study in PixArt, the Optical Finger Navigation (OFN) is evolving into wearables technology to enable users to interact well via the AR / VR devices in the virtual world.

The OFN technology had been widely used as the optical trackpad in mobile phones before the era of touch-screen smartphones. The ease of use of the OFN is making users quickly adapt to its friendly interaction on a gadget for the HMI control. Let’s see how it works!

Figure 1. OFN Optical System

Figure 2. OFN System Blocks

The OFN optical system consists of 4 main functional blocks: OFN chip, optical lens, infrared (IR) LED, and touch cover. The touch cover and FPC could be customized based on the exterior ID of the end product. The IR LED illuminates the fingertip through the optical lens set. The OFN chip optically acquires sequential fingertip images and mathematically determines the direction and magnitude of finger movements. The OFN chip is a System on Chip (SoC), which contains the image acquisition system, digital signal processor (DSP), and I2C serial port interface. The microscopic surface images of the fingertip are acquired and processed internally to output the motion data in Δx and Δy relative displacement and directions, as well as touch, single-click, and double-click detection. The OFN chip computes all the imaging and motion interpretation processing on-chip without an external MCU to process data, thus enabling OFN technology to be a genuinely low-power solution for wireless HID.

Figure 3. OFN Output Data

To be well fit as the sensing element in the wearables, PixArt is further transforming the OFN technology to meet the critical aspects of the wearables on the small form factor, low power consumption, high performance and ease of integration. The newly introduced PAW3008 is the OFN solution that unlocks the intuitive interaction of human and machine steering the metaverse.

PAW3008 Solution Key Features
Operating Temperature -20 to + 60 ° C
Operating Voltage VDDM: 2.5V ~ 3.6V

VDDIO: 1.62V ~ VDDM

Current Consumption Run mode: 2.5 mA

Sleep1 / Sleep2: 50/25 µA

Standby Power down: 15 µA

Interface I2C
High Speed ​​Motion Detection up to 24 IPS (inches per sec)
Selectable Resolution up to 3200 CPI (counts per inch)
Data Output

Motion Data: Δx and Δy displacement

Motion Directions

Touch Detection

Click Detection: Single-click and Double-click

Versatile Interrupt Pins For output of the motion, directions, touch and click
Chip Package Type 9-ball CSP
Chip Package Size 1.526 x 1.656 x 0.554 mm3
Chip & Lens Assembly

Dimension (L x W x H)

3.6 x 2.5 x 1.5mm3 (not including touch cover and FPC)

Figure 4. The New PAW3008 OFN Chip and Lens

(1) Superb Tiny in Size

The newly introduced miniaturized OFN solution, PAW3008 from PixArt, comes in a superb tiny size with the chip and lens assembly size of 3.6 (L) x 2.5 (W) x 1.5 (H) mm3. This small OFN solution could be embedded onto slim and thin wearables designs such as Smart rings, apparel, band straps, etc.

Figure 5. Assembly of the OFN Chip, Optical Lens, and IR LED

Figure 6. OFN in PixArt’s Smart Ring Demo Reference

(2) Low Power Consumption

Low power consumption is always the key purchasing factor for a wearable gadget. The PAW3008 chip can operate in the low power current consumption of 2.5mA when detecting any finger movement and down to 25μA in standby mode. For example, the low-power design of the OFN solution could make a Smart ring last for 7.5hours of continuous usage for a single charge of 21mAH *.

* Based on the PixArt’s usage model of the Smart Ring Demo Reference as shown in Figure 6. For detailed information, please get in touch us directly.

(3) High Performance

For an AR / VR gadget to be widely adopted, a good user experience is vital to the perception of human-to-machine in the virtual world. The PAW3008 OFN solution is the well-pick for sensing slight finger movement via the AR / VR wearables accessories to control the software contents. The most impressive OFN technology is detecting tiny and genuine finger gestures. The natural pinch of a fingertip across the small window area of ​​the touch cover can be accurately translated as pointer movements with scalable sensitivity and resolution from 50 to 3200 counts per inch (CPI) to navigate smoothly around the virtual 3D space. The OFN solution can detect high-speed movement up to 24 inches per second (IPS). Even a quick finger-glide is not a puzzle to the OFN.

Figure 7. Application Illustration of OFN Smart Ring

(4) Ease of Integration

PixArt always puts reliability and ease of integration as the top considerations in product design. A complete OFN optical system could be put together by integrating the OFN chip, optical lens, and touch cover onto an FPC. As there is no mechanical moving part and does not require any precise optical alignment, the holder of the optical lens snaps directly onto the OFN chip package and IR LED to form a functional optical system. A touch cover is added to the final product as a protective cover to increase the usage robustness and exterior styling design purposes.

Figure 8. OFN Module

Many HMI products that involve finger movement can use the OFN technology to maneuver the navigation control. The OFN could be found in many gizmos roving into people’s daily lives. It was initially started as a trackpad in mobile phones, then used in the remote controller, presenter, handheld pointing devices, etc. When the Smart gadgets become popular, the OFN is coming into sight to be the sensing element in Smart Wearables as the AR / VR accessories to unleash its great use to give a feeling of actual engagement in controlling the computer-generated cybernetic space. The new PAW3008 miniaturized OFN solution is perfect in its tiny size to fit into the slim, thin and compact enclosed space of Smart Wearables.

PixArt is not only supplying the OFN solution in the discrete IC package with its matching optical lens and standard module package but also does customization for the chip and module. To fit into niche applications for the automotive, medical, industrial, etc., market segments, PixArt can customize the OFN solution with different module designs, including the touch cover designs. For evaluation of the OFN solution, the comprehensive support tools are available by contacting PixArt to request the samples, evaluation kit, and design kit.

For more information, please get in touch with your local PixArt sales or contact us at https://www.pixart.com.

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