Reference Signal Generation Circuit for Incremental Encoder
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Solution Overview
Problem
Existing methods for generating reference signals in incremental encoders face challenges such as accuracy limitations due to manufacturing constraints, complexity in optical systems, and difficulties in miniaturization, which affect the precision and simplicity of the signal generation process.
Innovation Solution
A reference signal generation apparatus featuring a light-receiving unit with two orthogonal light-receiving element arrays, where the output reference signal starts and ends based on equal signal levels, allowing for a constant width signal independent of manufacturing limitations, and additional configurations to reduce fluctuations and foreign object interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single light-receiving element is used to generate reference signal, then the configuration is simple, but the accuracy is limited by manufacturing constraints on light-receiving element size and positioning
Solution Approach 1:
The light-receiving unit is divided into multiple light-receiving elements (first through fourth elements) arranged in arrays. Each element contributes to generating the reference signal, allowing high accuracy without requiring extreme miniaturization of individual elements. The segmentation enables parallel signal generation that improves overall precision while maintaining reasonable element dimensions.
Solution Approach 2:
The patent transitions from using a single light-receiving element to using multiple elements arranged in two-dimensional arrays with specific spatial relationships. The first and second elements are arranged in a first direction, while the third and fourth elements are arranged in a second direction orthogonal to the first. This dimensional arrangement enables accurate reference signal generation without relying solely on miniaturizing single elements.
2Measurement precision
If multiple reference point detection patterns are used to improve accuracy, then reference signal precision improves, but the optical system becomes more complex and miniaturization becomes difficult
Solution Approach 1:
Instead of using multiple reference point detection patterns on the scale, the patent segments the light-receiving function into multiple elements. The first light-receiving element array and second light-receiving element array process different spatial information from the same reference point detection pattern, achieving accuracy improvement without adding complex optical components or requiring scale miniaturization.
Solution Approach 2:
The patent uses light-receiving elements arranged in orthogonal directions (first direction and second direction) to extract positional information from the reference point detection pattern. This dimensional arrangement allows accurate reference signal generation without requiring the reference point detection pattern itself to be miniaturized, avoiding diffraction issues.
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 the generation of highly accurate reference signals with a simple configuration, maintaining constant width and reducing fluctuations, even under manufacturing constraints and potential foreign object interference.
Implementation Method 1
a reference point detection light-receiving unit that receives light from a reference point detection pattern, in which the light is emitted from a light source
Data Source
AI summary
A reference signal generation circuit generates a reference signal from a reading result of the reference point detection pattern. The first light-receiving element array includes a first light-receiving element that outputs a first signal, and a second light-receiving element that is disposed in a first direction of the first light-receiving element and outputs a second signal. A second light-receiving element array includes a third light-receiving element that outputs a third signal, and a fourth light-receiving element that is disposed in the first direction of the third light-receiving element and outputs a fourth signal. The second light-receiving element array is disposed in a second direction of the first light-receiving element array. The reference signal generation circuit outputs a reference signal that starts at a period when levels of the first and second signal become equal and ends at a period when levels of the third and fourth signal become equal.