Table Saw Auto Shutdown Using Workpiece Removal Sensing
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Solution Overview
Problem
Table tools often waste power and pose safety hazards when cutting large workpieces, as users cannot manually shut them down promptly due to being occupied with the cutting process.
Innovation Solution
A table tool with multiple working modes and an automatic shutdown feature that uses a sensing device to detect the removal of a workpiece, allowing for intelligent control and efficient power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual shutdown operation is used, then user can control the tool, but user cannot shut down in time when hands are occupied with cutting
Solution Approach 1:
The table tool automatically detects workpiece removal through the sensing device and shuts down the motor without requiring manual intervention. The system serves itself by monitoring its own operational state and autonomously transitioning from running to stopped state when the workpiece is removed, eliminating the need for user action.
Solution Approach 2:
The sensing device continuously monitors whether the workpiece is present on the table and provides feedback signals to the control circuit. Based on this feedback, the control circuit automatically adjusts the motor state, creating a closed-loop control system that responds to real-time conditions without manual input.
2Device complexity
If manual shutdown is required, then tool operation is simple, but power is wasted and safety hazards occur
Solution Approach 1:
The system automatically detects when the workpiece is removed and independently shuts down the motor without requiring user intervention. This self-service capability ensures power is not wasted while keeping the control mechanism relatively simple through automatic sensing and response.
Solution Approach 2:
The patent replaces manual mechanical operation with an automatic sensing and control system. The sensing device detects workpiece presence and the control circuit automatically manages motor power, substituting human action with an automated electromechanical system that prevents power waste.
3Loss of energy
If automatic shutdown function is added, then power waste is reduced, but device complexity increases
Solution Approach 1:
The sensing device provides continuous feedback about workpiece presence to the control circuit, enabling automatic shutdown decisions. This feedback mechanism reduces power waste by ensuring the motor only runs when needed, while the complexity is managed through a straightforward sensor-controller architecture.
Solution Approach 2:
The sensing device acts as an intermediary between the workpiece and the motor control system. It detects workpiece presence and translates this physical state into electrical signals that the control circuit uses to manage motor power, reducing the need for complex direct control mechanisms.
4Loss of time
If sensing device is used for automatic detection, then shutdown timing is improved, but device complexity increases
Solution Approach 1:
The sensing device provides real-time feedback on workpiece presence, enabling immediate detection and response when the workpiece is removed. This feedback loop minimizes shutdown response time while maintaining manageable system complexity through a direct sensor-to-controller signal path.
Solution Approach 2:
The patent replaces manual visual inspection and manual shutdown actions with an automated sensing system. The sensing device electronically detects workpiece presence and the control circuit automatically manages motor shutdown, substituting slow manual reactions with fast electronic detection and control.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A table tool (100B, 100) includes a table (10), a saw blade (20), a motor (30B, 30), a controller (70B, 70), a sensing device and a first switch (51B, 51). The table (10) has a workplane (11) on which a workpiece (40) is placed. The saw blade (20) acts on the workpiece (40). The motor (30B, 30) drives the saw blade (20) to rotate. The controller (70B, 70) is used for controlling rotation of the motor (30B, 30). The sensing device is electrically connected to the controller (70B, 70) and used for sensing a state of the workpiece (40) and outputting a first signal to the controller (70B, 70). The first switch (51B, 51) is used for a user to select a working mode from at least two working modes of the table tool (100B, 100). When the table tool (100B, 100) is in a first working mode, the controller (70B, 70) is configured to adjust a rotational speed of the motor (30B, 30) to be a first rotational speed based on an acquired first signal or a working parameter of the motor (30B, 30).