Reflection Photosensor Position Detection with Segmented Light Reception
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Solution Overview
Problem
Conventional position detection systems using magnetic sensors face challenges such as large size, high cost, difficulty in improving signal linearity, potential malfunctions due to magnetic field interactions, and accuracy issues related to magnetization and oxidation, which hinder long-distance and high-resolution position detection in camera modules.
Innovation Solution
A reflection type photosensor with alternating reflecting and non-reflecting surfaces is used, featuring multiple light receiving portions with different regions to enhance linearity and resolution, along with a calculating means that processes signals to achieve linear output and neutral potential conversion, allowing for accurate long-distance position detection without magnetic sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic sensors are used for position detection, then detection accuracy can be improved, but device size increases and cost increases
Solution Approach 1:
The patent replaces magnetic sensors with a reflection type photosensor system consisting of a light emitting element, light receiving element, and reflection plate with alternating reflective and non-reflective portions. This optical substitution eliminates the need for magnets and magnetic field detection, achieving compact device size while maintaining detection capability through optical reflection patterns.
Solution Approach 2:
The patent uses optical reflection patterns created by alternating reflective and non-reflective portions on the reflection plate to encode position information. Instead of directly detecting magnetic fields, the system captures optical copies/reflections of the pattern, processes the light intensity variations, and converts them to position signals, achieving accurate detection with smaller components.
2Measurement precision
If magnetic sensors are used for position detection, then detection accuracy can be improved, but manufacturing cost increases
Solution Approach 1:
The patent employs inexpensive optical components (light emitting LED, light receiving photodetector, and simple reflection plate with alternating patterns) instead of expensive magnetic sensors and magnets. These optical components are mass-producible, have simpler manufacturing processes, and eliminate the need for precise magnetization and assembly, significantly reducing manufacturing costs while maintaining detection accuracy.
3Volume of moving object
If conventional reflection type photosensor is used, then device size can be reduced, but detection resolution deteriorates for long distances
Solution Approach 1:
The reflection plate is divided into multiple alternating reflective and non-reflective portions along the moving direction, creating distinct optical zones. The light receiving element corresponds to multiple segmented regions, allowing the system to detect position by determining which segments are illuminated. This segmentation enables high-resolution position detection over long distances while maintaining a compact device form factor.
Solution Approach 2:
Different portions of the reflection plate have different optical properties (reflective vs. non-reflective), creating localized optical characteristics that encode position information. The light receiving element detects variations in reflected light intensity from different local regions, enabling precise position determination. This local differentiation of optical properties allows high-resolution detection without increasing overall device size.
4Measurement precision
If magnetic sensors are used for position detection, then signal detection can be improved, but signal linearity becomes difficult to improve
Solution Approach 1:
The reflection plate features periodic alternating patterns of reflective and non-reflective portions, creating regular periodic variations in reflected light intensity as the plate moves. This periodic optical signal is inherently easier to process and linearize than magnetic sensor outputs. The calculating unit can directly map the periodic light intensity variations to linear position measurements, simplifying signal processing and improving linearity without complex compensation circuits.
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 a compact, cost-effective position detection system capable of detecting distances over 10 mm with a resolution of 5 μm or less, eliminating magnetic field-related issues and maintaining accuracy even with temperature fluctuations, suitable for high-end camera modules and applications requiring long-distance and high-accuracy position detection.
Implementation Method 1
light from the light emitting element 3 is reflected on the reflection plate 5 and is input into the light receiving element 4
Implementation Method 2
a light emitting element 3 for emitting light in the direction of the reflection portion 12 and a light receiving element 8 for receiving light reflected on the reflection portion 12
Data Source
AI summary
An object of the present invention is to provide a position detecting device using a reflection type photosensor, which assures a small size and low cost and enables detection of a long distance of about 10 mm or more, and a position detecting method. The position of a moving body is detected by providing, on the moving body, a reflection plate (12) having reflecting surfaces (sa) and non-reflecting surfaces (sb) arranged alternately in a moving direction of the moving body, providing a light receiving element (8) of the reflection type photosensor (9) with, for example, two light receiving portions (8a and 8b) having different light receiving regions in the moving direction of the moving body, outputting output signals from these two light receiving portions (8a and 8b), and carrying out at least one calculation of adding, subtracting, dividing and function calculation of these two output signals.