Reflection Photosensor Position Detection Using Double-Sided Reflector
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Solution Overview
Problem
Existing position detecting devices using magnetic sensors and large magnets are bulky and costly, and those employing reflection type photosensors face challenges in accurately detecting positions beyond 1 mm due to size constraints and thermal sensitivity issues.
Innovation Solution
A position detecting device utilizing a pair of reflection type photosensors with a double-sided reflector and an operating circuit that processes the outputs of both sensors to calculate sums, differences, and ratios, allowing for accurate position detection without magnetic sensors or large magnets, and compensates for thermal fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic sensors and large magnets are used for position detection, then detection range can be extended to 5 mm or more, but device size becomes large and cost increases
Solution Approach 1:
The patent replaces the magnetic field-based detection system with an optical system using reflection type photosensors. This substitution eliminates the need for large magnets and magnetic sensors, significantly reducing device size while maintaining the ability to detect positions at 5 mm or more distance through optical reflection principles.
Solution Approach 2:
The patent changes the detection parameter from magnetic field interaction to optical reflection intensity. By measuring the intensity of reflected light at different distances, the system achieves position detection capability at 5 mm or more range without requiring the physical space for large magnets, thus resolving the contradiction between detection range and device size.
2Volume of moving object
If single reflection type photosensor is used for position detection, then device size is reduced, but detection accuracy deteriorates at distances beyond 1 mm
Solution Approach 1:
The patent divides the detection system into multiple reflection type photosensors arranged at different positions. Each photosensor detects reflected light intensity at its specific location, and the control unit processes signals from multiple sensors to calculate precise position information, achieving accurate detection at distances beyond 1 mm while maintaining compact device size.
Solution Approach 2:
The patent transitions from one-dimensional detection (single sensor) to multi-dimensional detection by arranging photosensors in specific spatial configurations. This dimensional expansion allows the system to triangulate and determine precise position at greater distances, overcoming the 1 mm accuracy limitation of single-sensor systems.
3Device complexity
If reflection type photosensor output is used for position detection, then device complexity is reduced, but thermal sensitivity causes detection errors
Solution Approach 1:
The patent implements a feedback mechanism where the control unit continuously monitors outputs from multiple reflection type photosensors and adjusts position calculations based on detected variations. This feedback processing compensates for thermal sensitivity effects, maintaining detection reliability while preserving the simple device configuration.
Solution Approach 2:
The system uses the reflected light signal itself to compensate for thermal effects. By analyzing the intensity and pattern of reflected light detected by multiple photosensors, the control unit can identify and correct thermal drift, allowing the system to self-correct detection errors without additional complex components.
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
Enables downsized, cost-effective, and high-sensitive position detection over a wide range (1 mm to 10 mm) with improved linearity and reduced thermal influence, suitable for camera modules with zoom functions.
Implementation Method 1
a position detecting device utilizing a pair of reflection type photosensors with a double-sided reflector
Implementation Method 2
reflection type photosensors... outputs of the reflection type photosensors are detected
Data Source
AI summary
There is provided a position detecting device using reflection type photosensors in which a position sensing of lens located not less than 1 mm apart from a sensor can be conducted.A pair of reflection type photosensors PR1 and PR2 are oppositely arranged, a double sided reflector 5 attached on a movable body is movably arranged between the pair of reflection type photosensors and a position of the double sided reflector 5 is detected from the outputs of these reflection type photosensors. In the position detecting device of the present invention, an operating formula in which linear values are obtained depending on a moving distance of the double sided reflector can be used. For example, when an output of one of the pair of reflection type photosensors is Vo1, and an output of the other is Vo2, the position detecting is conducted using the operating formula of (Vo1−Vo2)/(Vo1+Vo2).