Optical Ranging Sensor Light Spot Detection
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Solution Overview
Problem
Conventional optical ranging sensors have large sizes, high manufacturing costs, increased response time, and power consumption due to the separate packaging of CMOS image sensors and laser diodes, leading to inaccurate distance measurements and noise in determining the center of gravity of the light spot.
Innovation Solution
An optical ranging sensor with a light receiving unit having a matrix of light receiving cells arranged in two directions, where the size of the effective light receiving part is optimized to be between the radius and diameter of the light spot, allowing for reduced chip size and eliminating unnecessary signal processing, thereby improving performance and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the effective light receiving part is made large to accommodate light spot movement, then the light spot position can be accurately detected, but the chip size and manufacturing cost increase
Solution Approach 1:
The light receiving part is segmented into an effective light receiving part and an ineffective light receiving part. Only the effective portion is used for light spot position detection, while the ineffective portion is excluded from processing. This segmentation allows the effective area to be minimized to just what is needed for accurate detection, reducing overall chip size while maintaining measurement precision.
Solution Approach 2:
Different regions of the light receiving part are assigned different functions. The effective light receiving part is optimized for high-precision light spot detection with appropriate sensitivity, while the ineffective portion is either non-functional or used for other purposes. This local differentiation allows the detection-critical region to be small and precise without requiring the entire chip to be large.
2Adaptability or versatility
If separate packages are used for CMOS image sensor and laser diode, then each component can be optimized independently, but the overall device size and manufacturing complexity increase
Solution Approach 1:
The CMOS image sensor and laser diode are integrated into a single chip package rather than using separate packages. This merging reduces the overall device size, simplifies the manufacturing process by reducing the number of assembly steps, and eliminates alignment issues between separate components while maintaining the ability to optimize each component's design within the integrated structure.
3Reliability
If the effective light receiving part is made large to ensure light spot coverage, then detection reliability is improved, but power consumption and response time worsen due to processing unnecessary data
Solution Approach 1:
The ineffective light receiving part that generates unnecessary data is extracted and excluded from the signal processing pipeline. Only the effective light receiving part that actually contributes to accurate light spot position detection is processed. This extraction eliminates wasted computational resources, reducing power consumption and accelerating response time while maintaining or improving detection reliability through focused processing of relevant data.
4Measurement precision
If the effective light receiving part is made large to accommodate light spot variations, then measurement accuracy is maintained, but manufacturing cost increases
Solution Approach 1:
The light receiving part is segmented to identify and utilize only the effective portion needed for accurate distance measurement. By determining the minimum effective area required for the light spot to move through its full range, the chip size is reduced to this essential portion only. This segmentation enables cost-effective manufacturing by minimizing material usage and chip real estate while preserving the measurement precision needed for accurate distance detection.
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 solution enables accurate distance measurement with reduced sensor size and cost, faster response time, and improved signal-to-noise ratio, addressing the limitations of conventional sensors by optimizing the light receiving unit's size and structure.
Implementation Method 1
a light emitting element 12 for projecting a light beam on an object to be measured
Implementation Method 2
a light receiving element 13 for receiving reflected light resulting from reflection of the light beam from the object to be measured
Data Source
AI summary
An optical ranging sensor includes a light emitting unit for projecting a light beam on an object to be measured, a light receiving unit on which a light spot of reflected light of the light beam from the object is formed, and a processing circuit unit for processing output signals from the light receiving unit and detecting a distance to the object. The light receiving unit includes an effective light receiving part having light receiving cells arranged in matrix form in a first direction in which a position of the light spot moves as the object moves along a direction of an optical axis of the light emitting unit, and in a second direction orthogonal to the first direction. A size of the effective light receiving part in the second direction is not smaller than a radius of the light spot but not larger than a diameter thereof.