Substrate Rotation Speed Calculation via Vibration Noise Cancellation
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Solution Overview
Problem
Existing methods for calculating substrate rotation speed are hindered by vibrations and sounds that include noise from factors other than the notch hitting the roller, leading to inaccurate calculations.
Innovation Solution
A rotation speed calculation apparatus using multiple vibration or sound sensors to detect vibrations or sounds generated by a notch hitting rollers and the housing, with a calculator to subtract or add these signals to isolate the substrate's rotation speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single vibration sensor is used to detect vibrations when the notch hits the roller, then the rotation speed can be calculated, but the detected vibrations include noise from housing vibrations leading to inaccurate calculations
Solution Approach 1:
The detection system is segmented into multiple sensors: one sensor detects the combined vibration signal (notch hitting roller + housing vibrations) while another sensor detects only the housing vibrations. This segmentation allows the housing vibration noise to be separated and removed from the useful signal, improving rotation speed calculation accuracy.
Solution Approach 2:
The harmful housing vibration noise is extracted from the total detected signal using a separate vibration sensor. By taking out the noise component independently, the system can subtract it from the main signal to obtain a clean measurement of the notch-hitting vibrations, thereby improving measurement precision.
2Measurement precision
If multiple vibration sensors are used to detect and cancel housing vibrations, then the rotation speed calculation accuracy is improved, but the device complexity increases
Solution Approach 1:
An additional vibration sensor acts as an intermediary to detect housing vibrations separately. This intermediary sensor provides the noise signal that can be subtracted from the main detection signal, improving accuracy despite the increase in sensor count. The intermediary sensor enables noise cancellation without requiring complex signal processing of the main sensor output.
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
Accurately calculates substrate rotation speed by canceling noise from the housing vibrations, improving calculation accuracy even when notch-generated vibrations or sounds are small.
Implementation Method 1
a first vibration sensor configured to detect a vibration generated when a notch in a peripheral edge portion of a substrate to be cleaned hits a roller holding the peripheral edge portion of the substrate
Implementation Method 2
a second vibration sensor configured to detect a vibration of a housing defining a space in which the substrate is cleaned
Implementation Method 3
a rotation speed calculator configured to calculate a rotation speed of the substrate based on the vibration detected by the first vibration sensor and the vibration detected by the second vibration sensor
Implementation Method 4
a first sound sensor configured to detect a sound generated when a notch in a peripheral edge portion of a substrate to be cleaned hits a roller holding the peripheral edge portion of the substrate when the substrate is rotated by driving the roller to rotate
Implementation Method 5
a second sound sensor configured to detect a sound generated from a housing defining a space in which the substrate is cleaned
Implementation Method 6
a rotation speed calculator configured to calculate a rotation speed of the substrate based on the sound detected by the first sound sensor and the sound detected by the second sound sensor
Data Source
AI summary
Provided is a rotation speed calculation apparatus including: a first vibration sensor configured to detect a vibration generated when a notch in a peripheral edge portion of a substrate to be cleaned hits a roller holding the peripheral edge portion of the substrate when the substrate is rotated by driving the roller to rotate; a second vibration sensor configured to detect a vibration of a housing defining a space in which the substrate is cleaned; and a rotation speed calculator configured to calculate a rotation speed of the substrate based on the vibration detected by the first vibration sensor and the vibration detected by the second vibration sensor.