Light-Projection Device for ToF Range Finding Using 2D Array Scanning
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Solution Overview
Problem
Existing Time-of-Flight (ToF) range-finding methods face limitations in increasing luminous flux density without separating light flux, leading to reduced maximum measurable distance and accuracy due to decreased energy per flux and lower reflected light intensity.
Innovation Solution
A light-projection device with a two-dimensionally arranged light-emitting element array, a light-projection lens for adjusting light projection range, and a driving device for changing relative positions between the light source array and lens, along with a light source controller for varying light source array positions, allows for increased luminous flux density without flux separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If luminous flux is separated into a plurality of luminous fluxes using a diffraction optical element, then the density of luminous flux is increased, but the energy per luminous flux after separation decreases and the maximum measurable distance is shortened
Solution Approach 1:
The light source array segments the light emission into multiple independent light-emitting elements arranged in a two-dimensional pattern, allowing each element to emit light independently toward different spatial regions, thereby increasing luminous flux density without dividing existing flux into weaker components
Solution Approach 2:
The invention transitions from one-dimensional linear light sources to two-dimensional light source arrays, enabling light emission in multiple spatial dimensions simultaneously. This dimensional expansion increases the density of luminous flux in the measurement region while maintaining sufficient energy per flux path
2Quantity of substance
If luminous flux is separated using an optical element, then the density of luminous flux is increased, but the intensity of reflected light is lower and range finding accuracy may decrease
Solution Approach 1:
The light source array segments light emission into multiple independent elements that can be controlled individually, allowing optimized emission patterns that increase flux density while maintaining sufficient reflected light intensity for accurate measurement
Solution Approach 2:
The invention changes the spatial distribution parameters of light emission by arranging light-emitting elements in a two-dimensional array with specific pitch relationships. This parameter optimization enables increased luminous flux density while maintaining the reflected light intensity necessary for accurate range finding
3Quantity of substance
If the pitch of luminous flux is smaller than the pitch of light-emitting elements through flux separation, then the density of luminous flux is increased, but the configuration becomes more complex
Solution Approach 1:
Rather than using complex optical elements to separate and redistribute flux, the invention segments the light source itself into a two-dimensional array of light-emitting elements, directly generating high-density flux patterns without additional optical separation components
Solution Approach 2:
Instead of taking the conventional approach of using optical elements to separate existing flux from a single source, the invention inverts the approach by using multiple segmented light sources to directly generate the desired high-density flux distribution, eliminating the need for flux separation optics
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 configuration enhances the density of distance measurement points, maintains the maximum measurable distance, and improves range finding accuracy by increasing space resolution without reducing reflected light intensity.
Implementation Method 1
a light source array in which a plurality of light-emitting elements are two-dimensionally arranged; a light-projection lens that adjusts a light projection range of light emitted from the light source array
Data Source
AI summary
Disclosed is a light-projection device that is used for a range finding apparatus that computes a distance to an object that has reflected light, by measuring a time difference between a time when light is emitted and a time when reflected light is detected. The light-projection device comprises a light source array in which a plurality of light-emitting elements are two-dimensionally arranged and a light-projection lens that adjusts a light projection range of light emitted from the light source array. The light projection device further comprises a driving device that changes relative positions between the light source array and the light-projection lens and a light source control unit that switches on the light source array under conditions where the light source array is in different positions.