Configurable Photodetector Array for Accurate Optical Encoder Mapping

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Solution Overview

Problem

Existing encoder systems face inaccuracies due to forced assignment of pixels to single quadrature states and uniform light intensity treatment, which limits their ability to handle varying code wheel configurations and non-uniform light sources.

Innovation Solution

A configurable photodetector array that allows pixels to be assigned to multiple states and weighted differently, enabling accurate mapping of optical energy contributions and compensating for non-uniform light intensity profiles, thereby improving encoder system accuracy and versatility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If pixels are forced to be assigned to a single quadrature state, then the encoder chip can be simplified in configuration, but measurement precision deteriorates due to inaccuracy in detecting optical energy contributions

Engineering Contradiction:

Improveencoder chip configurationVSAvoidposition detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent segments the optical energy detection by dividing the pixel array into multiple groups, where each group is assigned to a specific quadrature state. This allows different segments of pixels to contribute to different quadrature components (A+, A-, B+, B-), enabling accurate reconstruction of optical energy contributions while maintaining a simplified single-chip configuration.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent makes the encoder chip universal by implementing a configurable pixel assignment mechanism that can adapt to different code wheel configurations. The same encoder chip can be used with various code wheels by reconfiguring which pixels are assigned to which quadrature states, thereby achieving multi-functionality without requiring multiple specialized chips.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Device complexity

If uniform weights are applied to current outputs from pixels, then the processing is simplified, but measurement precision deteriorates when the light source generates a non-uniform light intensity profile

Engineering Contradiction:

Improvesignal processing complexityVSAvoidposition detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent applies local quality by assigning different weights to different pixels or pixel groups based on their specific characteristics and the light intensity profile. Instead of using a uniform weight for all pixels, the system optimizes weights locally for each pixel or group to compensate for non-uniform light intensity distribution, thereby improving measurement precision while adding manageable complexity to the signal processing.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If a single integrated circuit design is used for various encoder configurations, then manufacturing cost and supply chain complexity are reduced, but adaptability to different mechanical constructions and light sources is limited

Engineering Contradiction:

Improvemanufacturing cost and supply chain complexityVSAvoidadaptability to different encoder configurations

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamics by making the pixel-to-quadrature-state assignment configurable and adjustable. The encoder chip can dynamically reconfigure which pixels are assigned to which quadrature states based on the specific code wheel configuration and light source characteristics. This configurability allows a single integrated circuit design to adapt to various encoder configurations, maintaining both ease of manufacture and versatility.

Inventive Principle:

Principle #15Dynamics

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 the use of a single integrated circuit design for various encoder configurations, reducing costs and complexity in the supply chain while enhancing the accuracy and adaptability of encoder systems to different mechanical constructions and light sources.

Implementation Method 1

an encoder chip (e.g., an optical sensor integrated circuit) including one or more photodetectors that receive the modulated light and generate electrical signals in response thereto

Methodology Applied

Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentUS11378422B2Method and apparatus for improved performance in encoder systems by configuring a detector array using a partition map and assigning weights to output currents of the detector array

Publication Date: 2022.07.05 TT ELECTRONICS PLC

AI summary

An encoder system includes a configurable detector array, wherein the configurable detector array includes a plurality of detectors. The encoder system may also include a memory operable to store a partition map that defines a state for each of the plurality of detectors. The encoder system may also include an emitter operable to generate a flux modulated by a motion object, wherein the configurable detector array is operable to receive the flux and generate respective current outputs for each of the detectors in response to the flux. In an embodiment, the current outputs from detectors having a same state are grouped together. The encoder system may also include one or more current duplicators to duplicate the current outputs from detectors having one state to group with the current outputs from detectors having a different state. The encoder system may also adjust weights of the current outputs.