Code Wheel Index Region Layout for Stable Encoder Pulse Widths
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Solution Overview
Problem
Conventional code wheels face issues with index signal pulse width variation due to assembly and spatial tolerances, leading to reduced index gating margin and potential missing or double indexing.
Innovation Solution
The code wheel design includes an index region with a first region closer to the signal region and a second region larger than the first, ensuring balanced pulse widths and increased index gating margin through a processing circuit that determines the wheel's rotation based on code and index signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional index region is used in the code wheel, then the structure is simple, but the pulse width variation increases due to assembly and spatial tolerances
Solution Approach 1:
The index region is divided into two distinct zones: a first region closer to the signal region and a second region farther away. This local differentiation allows each zone to contribute differently to the generated light pattern, compensating for tolerance variations and achieving more consistent pulse widths across different assembly conditions.
Solution Approach 2:
The index region employs an asymmetric design where the first region and second region have different characteristics. This asymmetry is intentionally designed to counterbalance the effects of assembly tolerances and spatial variations, resulting in more uniform light pattern widths and reduced pulse width variation in the generated index signal.
2Ease of manufacture
If assembly tolerances are present, then manufacturing is easier, but the index gating margin is reduced
Solution Approach 1:
The invention changes the spatial parameters of the index region by creating two distinct regions at different distances from the signal region. This parameter modification allows the system to maintain adequate index gating margin even when assembly tolerances cause variations in component positioning, thereby improving reliability without compromising ease of manufacture.
3Device complexity
If the index region is equidistant from the signal region, then the structure is symmetric and simple, but the light pattern width varies
Solution Approach 1:
Instead of maintaining uniform symmetry, the index region implements local quality differentiation with two zones at different distances from the signal region. This approach prioritizes light pattern width consistency over geometric symmetry, ensuring that the generated light patterns have more uniform widths despite the asymmetric arrangement.
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 more balanced index pulses and improved index gating margin, enhancing the reliability of the encoding system by reducing pulse width variation and preventing missing or double indexing.
Implementation Method 1
a signal region, configured to receive light and generate at least one code signal according to the light
Implementation Method 2
an index region, configured to generate an index signal according to the light
Data Source
AI summary
A code wheel comprising: a signal region, configured to receive light and generate at least one code signal according to the light; and an index region, configured to generate an index signal according to the light, wherein the index signal represents a complete rotation of the code wheel. The index region comprises a first region with a first region and comprises a second region with a second region larger than the first region. The first region is closer to the signal region than the second region. The code wheel may be applied to an encoding system with a processing circuit, which is configured to determine a rotation of the code wheel according to the code signals and the index signal.