Scanning Laser Projector Depth Mapping Power Allocation

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Solution Overview

Problem

Scanning laser projectors face power limitations when combined with depth mapping, and existing depth mapping sensors have limited flexibility in generating 3D maps with fixed resolutions, restricting the combination of image projection and depth mapping capabilities.

Innovation Solution

The solution involves a scanning laser projector system that temporally separates projected image pixels and depth mapping pulses, allowing for maximum power usage in both functions without overlap, and dynamically adjusts scanning mirror motion to modify the characteristics of the 3D point cloud, such as resolution and data density.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If scanning laser projector combines image projection and depth mapping functions, then versatility is improved, but power consumption increases beyond available limits

Engineering Contradiction:
ImprovefunctionalityVSAvoidpower consumption
Core Design Contradiction:
Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The system alternates between image projection mode and depth mapping mode in periodic time slots. During image projection time slots, the laser projects image pixels. During depth mapping time slots, the laser projects depth mapping pulses. This periodic switching allows both functions to operate at full power without simultaneous power consumption, resolving the contradiction between versatility and power consumption.

Inventive Principle:
Principle #19Periodic action

2Ease of manufacture

If depth mapping sensor uses fixed-resolution CMOS imaging sensor, then manufacturing simplicity is improved, but adaptability in resolution is reduced

Engineering Contradiction:
Improvesensor simplicityVSAvoidresolution flexibility
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The system uses a scanning mirror with controllable scan parameters (scan rate, scan amplitude, number of scan lines) to dynamically adjust the resolution and data density of the depth map. This dynamic control allows the same simple sensor hardware to produce depth maps at multiple resolutions, resolving the contradiction between manufacturing simplicity and resolution flexibility.

Inventive Principle:
Principle #15Dynamics

3Illumination intensity

If scanning laser projector uses maximum power for image projection, then image quality is improved, but power available for depth mapping is reduced

Engineering Contradiction:
Improveimage brightnessVSAvoidpower for depth mapping
Core Design Contradiction:
Illumination intensityVSUse of energy by moving object

Solution Approach 1:

The system divides time into periodic slots: image projection time slots where maximum power is allocated to image pixels for high image brightness, and depth mapping time slots where maximum power is allocated to depth mapping pulses. This temporal separation allows each function to receive full power allocation without compromising the other, resolving the power allocation contradiction.

Inventive Principle:
Principle #19Periodic action

4Measurement precision

If scanning laser projector allocates power for depth mapping, then depth mapping capability is improved, but image projection power is reduced

Engineering Contradiction:
Improvedepth mapping accuracyVSAvoidprojected image brightness
Core Design Contradiction:
Measurement precisionVSIllumination intensity

Solution Approach 1:

The system uses periodic time slot allocation where depth mapping pulses receive full power during their dedicated time slots, ensuring measurement precision. Image projection receives full power during its dedicated time slots, ensuring image brightness. The periodic switching eliminates power competition between the two functions, resolving the contradiction between depth mapping accuracy and image brightness.

Inventive Principle:
Principle #19Periodic action

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

This approach enables full power utilization for both image projection and depth mapping without compromising image quality or resolution, providing flexible and high-resolution 3D surface mapping capabilities.

Implementation Method 1

at least one source of laser light configured to generate a laser beam

Methodology Applied
Scientific EffectLaser: Laser

Implementation Method 2

at least one scanning mirror configured to reflect the laser beam

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 3

depth mapping device configured to receive reflections of the depth mapping pulses from a surface and generate a 3-dimensional point cloud of the surface based at least in part on timing of the received reflections

Methodology Applied
Scientific EffectTime of flight: Time of Flight

Data Source

PatentEP3497926B1Devices and methods for providing depth mapping with scanning laser image projection
Publication Date: 2021.09.01 MICROVISION INC
  • EP3497926B1 patent drawingFigure 1
  • EP3497926B1 patent drawingFigure 2
  • EP3497926B1 patent drawingFigure 3A

AI summary

Devices are described herein for combining image projection with surface scanning. In general, the devices and methods utilize at least one source of laser light to generate a laser beam (102), and scanning mirror(s) (104) that reflect the laser beam into a pattern of scan lines. The source of light is controlled to selectively generate projected image pixels during a first portion of the pattern of scan lines, and to selectively generate depth mapping pulses during a second portion of the pattern of scan lines. The projected image pixels generate a projected image, while the depth mapping pulses are reflected from the surface, received, and used to generate a 3-dimensional point clouds that describe the measured surface depth at each point. Thus, during each scan of the pattern both a projected image and a surface depth map can be generated.