Optical Encoder Amplitude Normalization for Precision
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing position detection systems, such as absolute encoders, face errors due to fluctuations in light source emission and uneven reflectance, leading to increased size requirements for correction mechanisms.
Innovation Solution
An optical encoder with a sensor unit integrated into a light receiving and emitting unit, featuring a patterned scale with alternating areas of different pitches, where the signal processor normalizes amplitude signals to reduce errors and maintain precision without increasing detector size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a monitoring light receiving element and reference pattern are added to correct light amount fluctuations, then detection precision is improved, but device size increases
Solution Approach 1:
The patent extracts the light amount correction function from a separate monitoring system and integrates it into the main detection channel by using the same light receiving element for both position detection and light amount normalization, eliminating the need for dedicated monitoring components
Solution Approach 2:
The light receiving element is designed to serve multiple functions: detecting the optical pattern for position determination and simultaneously measuring light amount for normalization, thereby eliminating the need for separate monitoring elements and reducing overall device size
2Device complexity
If the encoder structure is simplified to reduce size, then device complexity is reduced, but detection precision deteriorates due to light amount fluctuations
Solution Approach 1:
The system uses its own detection signal to perform light amount correction by normalizing the output signal with the measured light amount, eliminating the need for external correction mechanisms and maintaining precision with simplified structure
Solution Approach 2:
The patent changes the parameter being measured from raw light intensity to normalized amplitude by dividing the detection signal by the light amount, thereby compensating for fluctuations and maintaining precision without additional hardware
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 system achieves precise position detection by normalizing amplitude signals, reducing the influence of light source fluctuations and uneven reflectance, while maintaining a compact design.
Implementation Method 1
a light receiving element array... converts an output... into positional information
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
An encoder includes a scale (20) that includes a pattern row, a detector array (16), and a signal processor (30). The pattern row has a plurality of different modulation periods in the moving direction, an amplitude of the energy distribution in the pattern having at least one modulation period being configured to change with a position of the scale in the moving direction. The signal processor acquirers an amplitude of an energy distribution of a corresponding modulation period based on an output signal from the detector array, and an amplitude signal obtained by normalizing a plurality of amplitudes obtained by the plurality of amplitude acquirers, the amplitude signal serving as a position signal representative of the position of the scale.