Linear Encoder Calibration Using Read Head Reference Points
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Solution Overview
Problem
Current linear encoders face challenges in achieving high precision due to environmental influences and aging effects, which cause shifts in the mass embodiment relative to the read head, leading to inaccuracies in position measurement, especially in applications requiring precise distance measurements.
Innovation Solution
A linear encoder with a calibration method that uses detection reference points to determine the position of code elements with high precision, allowing for the establishment of a standard detection distance, enabling accurate calibration without external temperature determinations, and allowing the mass embodiment to be composed of less precise materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the mass embodiment is made from conventional materials (steel, plastic, glass, ceramic), then manufacturing cost and ease of production are improved, but measurement precision deteriorates due to thermal expansion and aging effects causing position drift
Solution Approach 1:
The patent changes the reference frame from the mass embodiment to the read head. By establishing calibration references on the read head (which has negligible thermal expansion) rather than on the mass embodiment, the system compensates for thermal and aging effects. The calibration data is stored in the read head and used to correct position measurements, effectively decoupling measurement precision from the thermal stability of the mass embodiment material.
Solution Approach 2:
The patent replaces the mechanical approach of using thermally stable materials for the mass embodiment with an electronic/software-based solution. Instead of relying on the physical stability of the mass embodiment, the system uses digital calibration data stored in memory to compensate for position drift caused by thermal expansion and aging, substituting mechanical material stability with electronic data processing.
2Measurement precision
If code calibration is performed to assign position values to code elements, then measurement precision is improved, but device complexity and calibration difficulty increase due to the need for external position determination means and temperature compensation
Solution Approach 1:
The read head performs self-calibration by using its own internal calibration references (which are thermally stable) to determine the position of code elements on the mass embodiment. The calibration process is automated and uses the read head's sensor unit to detect code elements and calculate position values without requiring external calibration equipment or manual intervention, making the system self-sufficient.
Solution Approach 2:
The patent introduces calibration references as intermediary elements on the read head that serve as a stable reference frame. These calibration references act as mediators between the read head and the mass embodiment, allowing the system to establish accurate position relationships without directly measuring the mass embodiment's dimensions, thereby simplifying the calibration process.
3Adaptability or versatility
If the read head is moved in relation to the mass embodiment for scanning, then measurement capability is improved, but reliability deteriorates due to relative movement causing position drift and measurement errors
Solution Approach 1:
The patent implements feedback through continuous calibration. The read head detects code elements at multiple positions during normal operation and uses this information to update calibration data in real-time. This feedback mechanism allows the system to compensate for position drift caused by relative movement, maintaining measurement reliability even as the read head moves along the mass embodiment.
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
This approach enables high-precision distance measurements independent of temperature influences, reducing manufacturing and maintenance demands on the mass embodiment, and allowing for simpler calibration without external position determination means, thereby lowering production and maintenance costs.
Implementation Method 1
The scanning of the mass embodiment is performed in this case in a contactless manner, generally based on optical, inductive, magnetic, or capacitive physical principles. For example, the read head can have illuminating means, which irradiate a mass embodiment having light-reflective or light-scattering (reflected light scanning) or light-transmitting (transmitted light scanning) markings with light. The light is incident therefrom on a light-sensitive pickup of a sensor, for example, on a photocell or a CCD array.
Data Source
AI summary
A linear encoder can have a mass embodiment having a position code marking, a read head having a calibration means, and a control and analysis unit, and calibration method for calibrating a position code made of code elements using the read head. The read head has a sensor unit having at least two detection reference points, the detection distance of which establishes at least one standard with high precision. In the scope of the calibration method, calibrated position values are prepared for code elements with the aid of the standard, which is determined with high precision, and are stored in the control and analysis unit.