CMOS Optical Encoder Layout for Integrated Light Sensing
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Solution Overview
Problem
Conventional optical encoders require numerous production steps and separate components for the light source and photodiodes, leading to inefficiencies and high costs.
Innovation Solution
Integrating the transmitter and receiver units onto the same semiconductor substrate, such as silicon, using a CMOS process, to form a compact and economical optical encoder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the light source and photodiodes are made of different semiconductor materials (direct bandgap for light source, indirect bandgap for photodiodes), then the optical efficiency is improved, but the manufacturing complexity and number of production steps increase significantly
Solution Approach 1:
The patent merges the light source and photodiodes onto the same semiconductor substrate, integrating previously separate components into a unified structure. This combination maintains optical efficiency while eliminating the need for complex multi-material integration processes, as both components are now fabricated using the same indirect bandgap semiconductor material and manufacturing steps.
Solution Approach 2:
The patent changes the fundamental material parameter by using indirect bandgap semiconductor material for both the light source and photodiodes, rather than using different materials (direct bandgap for light source, indirect bandgap for photodiodes). This parameter change simplifies manufacturing while the patent compensates for the lower optical efficiency of indirect bandgap materials through optimized device design and structure.
2Reliability
If the light source and photodiodes are spatially separated and aligned, then the optical performance is maintained, but the alignment precision and production time increase
Solution Approach 1:
The patent merges the light source and photodiodes onto the same semiconductor substrate, eliminating the need for spatial separation and alignment between separate components. Both elements are fabricated in fixed relative positions during the same manufacturing process, ensuring precise alignment without requiring additional alignment steps or specialized equipment.
Solution Approach 2:
The patent performs the alignment action during the initial fabrication process by defining the relative positions of the light source and photodiodes through standard semiconductor manufacturing steps (such as photolithography and etching). This preliminary action ensures precise alignment is built into the structure from the start, eliminating the need for subsequent alignment operations.
3Adaptability or versatility
If separate components are used for light source and photodiodes, then the design flexibility is improved, but the production cost and assembly complexity increase
Solution Approach 1:
The patent combines the light source and photodiodes into a single integrated component on one semiconductor substrate, eliminating separate manufacturing and assembly processes. This integration reduces production cost by eliminating multiple fabrication steps, materials, and assembly operations, while the patent maintains design flexibility through the ability to configure the integrated components in different arrangements.
Solution Approach 2:
The patent creates a universal semiconductor substrate that can serve multiple functions: fabricating both the light source and photodiodes, providing mechanical support, enabling electrical connections, and ensuring precise alignment. This multi-functional substrate reduces the need for separate components and simplifies the overall manufacturing process.
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 integration reduces manufacturing steps and costs while ensuring precise alignment and compactness, enhancing the encoder's efficiency and cost-effectiveness.
Implementation Method 1
a light source (light-emitting diode, LED)... configured to send measuring light in the direction of the coding element
Implementation Method 2
receive measuring light emitted by the transmitter unit and reflected by at least one part of the coding element
Implementation Method 3
at least one receiver unit... configured to receive measuring light... and to generate and output a measurement signal based on the received measuring light
Data Source
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AI summary
An optical encoder comprises a first part and a second part, which are movable relative to one another, a coding arranged on the first part, at least one transmitting unit arranged on the second part, which is designed to transmit measuring light in the direction of the coding, at least one receiving unit arranged on the second part, which is designed to receive measuring light emitted by the transmitting unit and reflected by at least part of the coding and to generate and output a measuring signal based on the received measuring light, and at least one evaluation unit which is designed to determine a relative position between the first and the second part based on the output measuring signal, wherein the transmitting unit and the receiving unit are arranged on the same semiconductor substrate.