Substrate Transfer Arm Notch for Accurate Overlap Detection
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Solution Overview
Problem
Existing transfer apparatuses struggle to individually detect and specify multiple substrates mounted on transfer arms, especially due to spatial restrictions and the inability to accurately differentiate between substrates using transmission-type sensors.
Innovation Solution
A transfer apparatus equipped with reflection-type distance measuring sensors and a notch on the holding arm, allowing for the detection of substrates by projecting an optical axis based on a reference surface and detecting differences in light-receiving positions between reflected light beams from the reference surface and the substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If transmission-type sensors are used to detect substrates, then the detection can be performed through the holding arm structure, but the ability to accurately differentiate between multiple substrates is lost due to spatial restrictions
Solution Approach 1:
The patent replaces transmission-type sensors with reflection-type distance measuring sensors. This substitution changes the detection mechanism from transmitting light through the holding arm to measuring the distance of reflected light from the substrate surface, enabling accurate differentiation of multiple substrates without spatial restrictions
Solution Approach 2:
The patent changes the detection parameter from light transmission intensity to distance measurement based on light reflection time or phase. This parameter change allows the system to distinguish multiple substrates at different positions along the optical axis, resolving the inability to differentiate substrates with transmission-type sensors
2Productivity
If multiple substrates are held on transfer arms, then the transfer efficiency is improved, but the ability to individually detect and specify each substrate is lost
Solution Approach 1:
The patent introduces the holding arm structure as an intermediary reference object with known geometric features (the tip surface). By measuring the distance from the sensor to this reference surface and comparing it with the distance to the substrate, the system can calculate the substrate's position and identity, thereby recovering the position information that would otherwise be lost when multiple substrates are held simultaneously
Solution Approach 2:
The patent replaces the mechanical approach of individually positioning and detecting substrates with an optical measurement system. The reflection-type sensors measure distances to multiple substrates simultaneously, and the control unit processes these measurements to identify and specify individual substrates, maintaining transfer efficiency while recovering position information
3Strength
If the holding arm structure is solid without openings, then the mechanical strength is maintained, but the optical axis cannot pass through to detect substrates behind the arm
Solution Approach 1:
The patent extracts a portion of the holding arm structure to create an opening or window at the tip of the arm. This opening allows the optical axis of the reflection-type sensor to pass through and reach the substrate behind the arm, enabling detection without compromising the overall mechanical strength of the holding arm
Solution Approach 2:
The patent applies local quality change by creating a specific opening only at the tip region of the holding arm where optical access is needed, while maintaining the solid structure in other regions to preserve mechanical strength. This localized modification allows optical detection without globally weakening the structure
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
Enables accurate and reliable detection of multiple substrates, improving the efficiency of substrate transfer and reducing errors associated with spatial restrictions and misalignment.
Implementation Method 1
detecting a difference in a light-receiving position between a diffused and reflected light beam from the reference surface and a diffused and reflected light beam from the substrate
Data Source
AI summary
A transfer apparatus transfers a first substrate and a second substrate while holding the first substrate and the second substrate to overlap each other in a plan view. The transfer apparatus includes: a first holding arm configured to hold the first substrate in a horizontal direction; a second holding arm configured to hold the second substrate in the horizontal direction; a first detection sensor configured to detect presence/absence of the first substrate held by the first holding arm; and a second detection sensor configured to detect presence/absence of the second substrate held by the second holding arm, wherein the first detection sensor includes a sensor configured to detect the presence/absence of the first substrate, and wherein the first holding arm includes a notch formed at least at an inner end portion of a tip of the first holding arm and configured to allow the optical axis to pass therethrough.