SPAD Array Depth Sensing with Scanning Beam
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional depth cameras for virtual reality (VR) and augmented reality (AR) systems face challenges in achieving high accuracy and resolution while maintaining a small form factor and low power consumption, particularly with structured light methods that result in unused pixels and sensitivity trade-offs, and indirect time of flight systems that require complex computations and multiple image captures.
Innovation Solution
A depth camera assembly (DCA) with a transmitter and receiver, utilizing a beam steering assembly to generate a wide field-of-view and a two-dimensional array of single photon avalanche diode (SPAD) pixels, where the controller activates specific pixels to reduce ambient light and enhance depth information determination, allowing for efficient power usage and accurate depth mapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If structured light is used for depth sensing, then depth measurement capability is provided, but many pixels remain unused and accuracy depends on emitter-detector separation
Solution Approach 1:
The patent segments the sensor array into multiple independently controllable regions or groups of pixels. By activating only specific pixel groups corresponding to the scanned angular position, the system divides the large sensor array into smaller functional units, thereby improving the utilization of the sensor area while maintaining depth measurement capability.
Solution Approach 2:
The system dynamically activates different sets of pixels based on the angular position of the scanned beam. This dynamic reconfiguration allows the sensor array to adapt to the scanning pattern, ensuring that only the necessary pixels are active at any given time, thus improving area utilization and reducing power consumption.
2Adaptability or versatility
If a large sensor array is used to capture wide field-of-view, then more pixels are available for depth sensing, but power consumption increases
Solution Approach 1:
Instead of activating the entire sensor array simultaneously, the system activates only a partial subset of pixels at each moment, corresponding to the current angular position of the scanned beam. This partial action approach maintains wide field-of-view coverage capability while significantly reducing power consumption by keeping only necessary pixels active.
Solution Approach 2:
The system employs periodic scanning of different angular positions, with each position activating a specific set of pixels. This periodic activation pattern allows the sensor array to cover a wide field-of-view over time while maintaining low power consumption during each individual measurement cycle.
3Measurement precision
If indirect time of flight is used, then depth can be measured independently per pixel, but complex computations and multiple image captures are required
Solution Approach 1:
The system performs preliminary spatial encoding of the optical paths using the scanning beam pattern before detection. By pre-organizing which pixels receive light from which directions through controlled scanning, the system simplifies subsequent depth computation, avoiding the need for complex post-processing algorithms required in conventional indirect time-of-flight systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The DCA provides accurate and efficient depth information with reduced power consumption, enabling immersive VR/AR experiences by effectively utilizing a wide field-of-view and minimizing unused pixels, thus overcoming the limitations of conventional methods.
Implementation Method 1
an imaging device including a detector that comprises a two dimensional array of pixels that each include a single photon avalanche diode (SPAD)
Implementation Method 2
the beam steering assembly deflects the one or more optical beams to generate outgoing light having a relatively large angular spread
Data Source
AI summary
A depth camera assembly (DCA) includes a light generator emitting a beam of light into a local area and a detector. The detector captures light from the beam reflected by objects in the local area to a portion of an array of pixels that each include a single photon avalanche diode (SPAD). The location of the portion of the array is based in part on the angle of the beam emitted from the projector. The DCA identifies a set of pixels of the array corresponding to the portion and selectively retrieves current generated from the reflected light by the pixels in the portion of the array without retrieving current generated by pixels in other portions of the array.