Optical Encoder Phase Shifter for Variable Interpolation
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Solution Overview
Problem
Conventional optical encoders face limitations in adapting to different interpolation factors, requiring changes in phase shifter circuits and resistor mixers, which complicates the adjustment of phase shifts and reduces positioning resolution.
Innovation Solution
A phase shifter circuit with four resistor strings, each having M identical resistors, where tape-out nodes are strategically located between resistors to generate phase-shifted signals adaptable to various interpolation factors, allowing for fine-tuning of phase deviations by adjusting tape-out positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional phase shifter circuits with fixed resistor mixers are used, then the circuit structure is simple, but the adaptability to different interpolation factors is poor and positioning resolution is limited
Solution Approach 1:
The patent implements a dynamic phase shifter circuit where the effective number of resistors in each resistor string can be adjusted through switching elements. This allows the circuit to adapt to different interpolation factors by dynamically reconfiguring the resistor networks, transforming a static circuit into one that can be adjusted based on positioning resolution requirements.
Solution Approach 2:
The patent designs a universal phase shifter circuit that can handle multiple interpolation factors (4-fold, 8-fold, 10-fold, etc.) using a single circuit structure. By incorporating switching elements that can selectively connect different numbers of resistors, the circuit achieves multi-functionality, eliminating the need for separate resistor mixers for each interpolation factor.
2Adaptability or versatility
If multiple resistor mixers are used for different interpolation factors, then adaptability to different interpolation factors is improved, but device complexity and the number of components increase
Solution Approach 1:
The patent merges multiple resistor mixer functions into a single integrated phase shifter circuit. By combining four resistor strings with switching elements in one circuit block, it achieves the functionality of multiple separate resistor mixers while reducing the total number of components and simplifying the overall structure.
Solution Approach 2:
The patent uses dynamic switching elements to reconfigure the resistor networks within a single circuit, allowing one phase shifter to perform the work of multiple static resistor mixers. This dynamic reconfiguration enables the circuit to adapt to different interpolation factors without requiring multiple physical mixer units.
3Measurement precision
If fixed phase shift circuits are used, then manufacturing is simple, but positioning precision and phase fine-tuning capability are limited
Solution Approach 1:
The patent introduces dynamic switching elements that allow post-manufacturing adjustment of phase shifts. This enables fine-tuning of positioning precision by selectively activating different resistor combinations, achieving high measurement precision while maintaining relatively simple manufacturing through a standardized circuit design with adjustable parameters.
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 the optical encoder to output phase-shifted signals suitable for different interpolation factors, enhancing positioning resolution and accuracy by allowing for easy calibration of phase deviations without the need for multiple resistor mixers.
Implementation Method 1
The first resistor string has M identical first resistors cascaded together, and two ends of the first resistor string are configured to receive the first signal and the second signal, respectively
Implementation Method 2
receive a first signal, a second signal, a third signal and a fourth signal sequentially having a 90-degrees phase shift
Data Source
AI summary
There is provided a phase shifter circuit of an optical encoder that receives four signals generated from photodiodes. The phase shifter circuit includes four resistor strings each coupled to two of the four signals having a 90-degrees phase pitch. By taping out different numbers of signals at different tape-out nodes of each of the four resistor strings, the phase shifter circuit is adapted to output signals for different interpolation factors without changing the mask set.