Arrangement Detector for Plate Objects Using Imaging Shape Matching
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Solution Overview
Problem
Conventional arrangement detectors for plate-shaped objects, such as semiconductor wafers, face challenges in accurately distinguishing between the presence of substrates and light blurring, especially when the substrates have angled or non-circular shapes, leading to misidentification and increased complexity in load port design.
Innovation Solution
An arrangement detector with an imaging means that captures images of the substrate edges, uses a judgement window with specific reference lines to determine shape matching rates, and includes an area calculation means to differentiate between single and double-layered substrates, reducing the risk of misidentifying light blurring as a normal substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a transmission type sensor is used to detect substrate storage states, then detection capability is improved, but the device requires sufficient space between the substrate outer peripheral surface and container inner wall surface, which increases the size of the load port or container transport system
Solution Approach 1:
The patent transitions from a transmission type sensor that requires lateral space to an imaging sensor that captures images from above, changing the detection dimension from horizontal to vertical. This allows detection without requiring sufficient space between the substrate edge and container wall, thus reducing load port size while maintaining detection capability
Solution Approach 2:
The patent uses an imaging sensor to capture optical images of the substrate, creating a visual copy that can be analyzed to determine storage states. This copying approach eliminates the need for physical transmission paths through the substrate edge space, allowing compact load port design
2Device complexity
If an imaging sensor is used to detect substrate storage states by discriminating light and dark, then device complexity is reduced, but light blurring from diffuse reflection causes false detection and misidentification
Solution Approach 1:
The patent applies local quality by using a light-shielding member positioned specifically at the container bottom to block diffuse reflected light only in the critical detection area. This localized intervention eliminates blurring in the substrate detection region without affecting overall system complexity or requiring complete redesign of the illumination system
Solution Approach 2:
The light-shielding member acts as an intermediary element that mediates between the light source and the imaging sensor. It selectively blocks harmful diffuse reflected light while allowing useful light from the substrate to reach the sensor, thereby improving detection accuracy without increasing device complexity
3Ease of manufacture
If the container size is increased to form space between the substrate and container wall for sensor arrangement, then sensor arrangement feasibility is improved, but the size of the load port and container transport system increases
Solution Approach 1:
The patent repositions the sensor arrangement from a lateral configuration requiring horizontal space to a vertical configuration where the imaging sensor captures images from above. This dimensional change enables sensor arrangement without increasing container size or load port dimensions
Solution Approach 2:
The imaging sensor configuration serves multiple functions: it detects substrate presence, determines storage states, and works with various substrate shapes and sizes. This universal approach eliminates the need for shape-specific sensor arrangements that would require additional space
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 effectively reduces the likelihood of misidentifying light blurring as a substrate, improves detection accuracy for both single and double-layered substrates, and allows for a more compact load port design that can handle various substrate shapes without increasing size.
Implementation Method 1
the light emitted from the light source is diffusely reflected inside the container
Data Source
AI summary
An arrangement detector for plate-shaped objects and a lord port including the same are provided. The arrangement detector for plate-shaped objects includes a judgement window setting means, a shape determination means for determining a shape matching rate by superimposing the judgement window on the image captured by the imaging means, and an object judgement means for judging the plate-shaped objects do not exist in the judgement window overlaid on the image captured by the imaging means, in case that the shape matching rate determined by the shape determination means is equal to or less than a predetermined value. A first reference line is a continuous straight line in the judgement window, and a second reference line is a collection of discontinuous line segments linearly arranged in the judgement window.