Optical Encoder Combining Rough and Fine Displacement Detection
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Solution Overview
Problem
Optical absolute displacement encoders require complex structures with multiple lattice arrangements and detecting heads, leading to increased size and complexity, and are unable to detect absolute displacement without zero point calibration, which can result in apparatus shutdown and disassembly after a crash event.
Innovation Solution
A displacement detecting apparatus that combines rough and fine relative rotational displacements using a single optical pattern and light-receiving element arrangement, allowing for absolute displacement detection without zero point adjustment by inclining the lattice arrangements relative to the tangential direction, enabling high-resolution detection with a simple structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple lattice arrangements and detecting heads are arranged in the scale to detect absolute displacement, then absolute displacement detection capability is improved, but device complexity and size increase
Solution Approach 1:
The patent combines multiple detection functions into a single detecting head by integrating both total light quantity detection and incremental displacement detection capabilities. The detecting head includes light receiving elements that simultaneously provide rough displacement information (for absolute position) and fine displacement information (for high-resolution measurement), eliminating the need for separate detection systems.
Solution Approach 2:
The detecting head is designed to perform multiple functions: it detects both the total light quantity (providing rough displacement for absolute position determination) and the incremental displacement signals (providing fine resolution). This multi-functional design allows a single component to replace what would traditionally require multiple separate systems.
2Reliability
If multiple lattice arrangements and detecting heads are arranged in the scale to detect absolute displacement, then absolute displacement detection capability is improved, but the size and weight of the system increase
Solution Approach 1:
The patent merges the functions of multiple detecting heads into a single integrated detecting head. By combining total light quantity detection and incremental displacement detection in one component, the overall system weight is reduced while maintaining absolute displacement detection capability.
3Measurement precision
If zero point calibration is performed to ensure accurate displacement detection, then measurement precision is improved, but operational continuity deteriorates due to apparatus shutdown and disassembly requirements
Solution Approach 1:
The system performs preliminary action by continuously tracking rough displacement through total light quantity detection. This preliminary tracking maintains absolute position information without requiring periodic shutdowns for calibration, allowing the system to recover quickly from crashes without losing positional accuracy.
Solution Approach 2:
The patent ensures continuity of useful action by implementing continuous absolute position tracking through total light quantity detection. The system maintains uninterrupted displacement detection capability, eliminating the need to stop operation for zero point calibration and ensuring continuous measurement accuracy.
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 reliable detection of absolute rotational displacement with high precision and reliability, reducing the need for zero point calibration and disassembly, even after a crash event, and allows for precise torque detection and robot control.
Implementation Method 1
a detecting head which has light-receiving elements of a lattice arrangement, which detect the optical pattern of the scale
Data Source
AI summary
The displacement detecting apparatus acquires a quantity of a relative rotational displacement between a scale and a detecting head, based on a change of outputs of the light-receiving elements. The displacement detecting apparatus acquires the quantity of the relative rotational displacement between the scale and the detecting head, by combining a quantity of a rough relative rotational displacement between the scale and the detecting head, which has been acquired from an output of the total of light quantities that are output from each of the light-receiving elements in the detecting head, with a quantity of a fine relative rotational displacement between the scale and the detecting head, which has been acquired from an incremental displacement signal that is output from each of the light-receiving elements in the detecting head.