Photoelectric Encoder Resolution via Phase Shifted Rectangular Waves
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Solution Overview
Problem
Conventional photoelectric encoders face limitations in achieving high resolution due to material processing constraints, leading to reduced effective light receiving element width and increased cost, with existing solutions struggling to maintain signal quality and mechanical strength.
Innovation Solution
A photoelectric encoder design featuring a light receiving section composed of 2n light receiving elements arranged side by side within a region wider than one pitch of the light transmitting/reflecting zones, utilizing a first and second rectangular-wave generation section to produce output signals with higher resolution, improving the effective light receiving element width and signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If glass is used as the material of the movable object to achieve high resolution, then measurement precision is improved, but device cost increases due to the need to ensure mechanical strength
Solution Approach 1:
The patent replaces expensive glass scale rulers with inexpensive synthetic resin scale rulers. The synthetic resin material allows for cost-effective manufacturing while achieving the required mechanical strength and resolution through optimized design and processing techniques.
Solution Approach 2:
The patent changes the material parameter from glass to synthetic resin, and optimizes the pitch and dimensions of the light passing zones to achieve high resolution without requiring expensive materials. This parameter optimization enables cost-effective high-resolution measurement.
2Measurement precision
If the pitch of light passing zones and light non-passing zones is reduced to increase resolution, then measurement precision is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent optimizes the pitch parameters of the light passing zones and light non-passing zones to achieve high resolution while maintaining reasonable manufacturing precision requirements. By carefully selecting and optimizing these dimensional parameters, the system achieves 300 dpi resolution without excessive machining constraints.
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 enables higher resolution outputs with improved signal strength and reduced cost, allowing for accurate detection of displacement and direction, while maintaining mechanical integrity.
Implementation Method 1
a light emitting element and a light receiving section to detect a movable object which has a light transmitting/reflecting zone for transmitting or reflecting light emitted from the light emitting element
Implementation Method 2
a light receiving section to detect a movable object which has a light transmitting/reflecting zone for transmitting or reflecting light emitted from the light emitting element toward the light receiving section
Data Source
AI summary
In the photoelectric encoder of the invention, as a light passing zone PZ of a movable object 21 travels by one pitch P, an output signal OUT2 of a second logical operation unit 26b comes to be delayed in phase by 45° with respect to an output signal OUT1 of a first logical operation unit 26a. Therefore, an output having a resolution two times higher than that of the movable object having a phase difference of 90° can be obtained, where the width of each of light receiving elements 22a-22d is (¼)P. Accordingly, the width of each of the light receiving elements can be made two times larger, compared with the case where the width of each of the light receiving elements is (⅛)P as in conventional optical encoders. Thus, the output strength of the detection signal can be increased, so that the S/N ratio can be improved.