Combined Position Index Track Optical Encoder
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Solution Overview
Problem
Conventional optical encoders with separate position and index tracks are larger in size, costly, and have limited resolution due to the complexity of track layout and alignment, which complicates precise tracking and increases the device's footprint.
Innovation Solution
A combined position and index track on the code wheel, utilizing a single track with optically distinguishable sections for both position and index detection, coupled with a combined photodetector array that includes position and index photodetectors, allows for reduced encoder size and improved alignment tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate position and index tracks are used on the code wheel, then position and index detection can be achieved, but the encoder size increases and manufacturing complexity increases
Solution Approach 1:
The patent combines the position track and index track into a single integrated track on the code wheel. The track contains both position markers and index markers in a unified structure, eliminating the need for separate tracks. This merging reduces the overall encoder size and simplifies the manufacturing process while maintaining the ability to detect both position and index information.
Solution Approach 2:
The single track on the code wheel serves multiple functions by incorporating both position detection markers and index detection markers. The track pattern includes alternating light-transmitting and light-blocking sections that encode both rotational position information and index information, allowing one track to perform the work of traditionally separate tracks.
2Measurement precision
If separate photodiode tracks are implemented for AB photodiodes and index photodiodes, then position and index signals can be detected separately, but alignment precision becomes more difficult to achieve
Solution Approach 1:
The patent merges the AB photodetectors and index photodetectors into a single integrated photodetector array. This unified array detects both position and index signals from the single combined track, eliminating the alignment challenges between separate photodiode tracks and their corresponding tracks on the code wheel.
Solution Approach 2:
The single combined track acts as an intermediary that translates both position and index information into a unified optical signal pattern. This intermediate representation simplifies the detection process by the photodetector array, as the track's alternating light-transmitting and light-blocking sections create a comprehensive signal that contains both position and index data.
3Measurement precision
If multiple separate tracks are used on the code wheel, then comprehensive motion monitoring is achieved, but the cost of the code wheel increases
Solution Approach 1:
The patent combines multiple separate tracks into a single integrated track structure on the code wheel. This single track contains all necessary markers for monitoring rotational position and number of revolutions, reducing the amount of material and manufacturing steps required compared to multiple separate tracks, thereby lowering production costs.
Solution Approach 2:
The single track performs multiple functions by encoding both position information and index information in its pattern of light-transmitting and light-blocking sections. This multi-functional design eliminates the need for separate dedicated tracks for different measurement purposes, simplifying the code wheel structure and reducing manufacturing complexity and cost.
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 a smaller, more cost-effective optical encoder with enhanced resolution and improved alignment tolerance, capable of accurately determining the rotational position and count of a moving part without the need for separate tracks, thus simplifying the design and increasing the device's usability.
Implementation Method 1
In a transmissive code wheel, the light is modulated as it passes through transmissive sections of a track on the code wheel. The transmissive sections are separated by non-transmissive sections. In a reflective code wheel, the light is modulated as it is reflected off of reflective sections of the track on the code wheel.
Implementation Method 2
As the light is modulated in response to the rotation of the code wheel, a stream of electrical signals is generated from a photodetector array that receives the modulated light.
Data Source
AI summary
An optical encoder. The encoder includes a coding element, an emitter, and a detector. The coding element has a track with a track pattern. The track pattern includes a plurality of optically distinguishable sections, which include a plurality of position sections and an index section. The emitter generates a light signal incident on the track of the coding element. The detector includes a combined position and index photodetector array. The combined position and index photodetector array includes a plurality of position photodetectors and an index photodetector. Embodiments of this type of optical encoder implement position and index sections in a single track on the coding element.