Linear Displacement Sensor Using Position Sensitive Detector
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical displacement sensors suffer from signal nonlinearity and accuracy errors due to unrecognized issues with light sources, leading to suboptimal precision and cost-effectiveness compared to LVDT-type sensors.
Innovation Solution
A position sensing device with a frame, guide bearing, motion element, position sensitive detector, and a position indicating emitter that uses a light source and emitter material to generate excitation light, forming a measurement spot on the detector, which maintains uniform intensity and reduces errors by absorbing and re-emitting light within specific wavelength ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional light source is used in an optical displacement sensor, then the device structure can be simple, but signal nonlinearity and accuracy errors occur
Solution Approach 1:
The patent introduces a correction filter as an intermediary element in the optical path between the light source and the detector. This filter compensates for the non-uniform intensity distribution of conventional light sources, eliminating signal nonlinearity and accuracy errors while maintaining the simplicity of the overall device structure.
2Measurement precision
If a correction filter is added to achieve homogenous illumination, then measurement accuracy improves, but device complexity and cost increase
Solution Approach 1:
The patent modifies the spectral characteristics of the light source by introducing a correction filter with specific transmission properties. This changes the intensity distribution parameter of the light to achieve uniform illumination, improving measurement accuracy without requiring a complete redesign of the device structure.
3Measurement precision
If LVDT-type sensors are used to achieve precise measurement, then measurement precision improves, but device complexity and cost increase compared to optical sensors
Solution Approach 1:
The patent replaces the mechanical LVDT sensing system with an optical sensing system. By using a light source, correction filter, and photodetector arrangement, the system achieves LVDT-level measurement precision while eliminating complex mechanical components, resulting in a simpler and lower-cost device.
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 provides improved linearity and accuracy with reduced signal nonlinearity and accuracy errors, resulting in a simpler, lower-cost, and more precise optical position sensing device.
Implementation Method 1
The position indicating emitter comprises an emitter material that absorbs light in the first wavelength range and responds by outputting excitation light generated within the emitter material, the generated excitation light including a second wavelength range
Implementation Method 2
The position sensitive detector is fixed relative to the frame and comprises a photodetector configured to provide an output that is responsive to the position of a light spot along a sensing axis direction
Data Source
AI summary
A position sensing device comprises a frame, a guide bearing, a motion element, a position sensitive detector, a light source, and a position indicating emitter. The motion element is guided by the guide bearing over a measuring range along a measuring axis direction. The light source is configured to radiate source light. The position indicating emitter moves with the motion element. The position indicating emitter comprises an emitter material that absorbs source light and outputs excitation light from the emitter material to form a measurement spot on the position sensitive detector. The measurement spot moves along the sensing axis direction of the position sensitive detector corresponding to the position of the motion element along the measuring axis direction. The position sensitive detector outputs at least one signal in response to the measurement spot which is indicative of the position of the motion element along the measuring axis direction.