Block Circuit for Power Tool Control Signal Malfunction
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Solution Overview
Problem
Power tools can malfunction due to issues with their control circuits, leading to unintended operation, which existing safety mechanisms fail to adequately prevent.
Innovation Solution
A block circuit is introduced between the control circuit and the actuation circuit to block the actuation of the drive unit when an abnormal control signal is detected, using logical operations with discriminant reference signals to determine signal abnormalities, thereby preventing the movable element from being moved by a malfunctioning control circuit without modifying existing circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a control circuit formed by a microcomputer is used to control the actuation circuit, then the control functionality and automation are improved, but the reliability deteriorates due to potential malfunctioning and abnormal control signals
Solution Approach 1:
A block circuit is introduced as an intermediary component between the control circuit and the actuation circuit. This block circuit receives the control signal from the control circuit and performs logical operations with discriminant reference signals to determine whether to block or transmit the control signal to the actuation circuit, thereby protecting against control circuit malfunction while maintaining automation
Solution Approach 2:
The block circuit implements a feedback mechanism by continuously monitoring the control signal from the control circuit and comparing it with discriminant reference signals. When an abnormal control signal is detected, the block circuit feeds back a blocking action to prevent the abnormal signal from reaching the actuation circuit, thus maintaining system reliability
2Reliability
If a safety switch is used to prevent malfunctioning, then the safety is improved, but the reliability deteriorates because the control circuit can still output abnormal control signals when the safety switch is on
Solution Approach 1:
The block circuit performs preliminary anti-action by proactively monitoring and blocking abnormal control signals before they can reach the actuation circuit. This prevents harmful unintended operation even when the safety switch is activated, addressing the limitation of existing safety switches
3Device complexity
If the actuation circuit is directly connected to the control circuit, then the device complexity is reduced, but the reliability deteriorates due to lack of protection against control circuit malfunction
Solution Approach 1:
The block circuit serves as a relatively simple intermediary component that can be integrated into the existing circuit without significantly increasing device complexity. It provides necessary protection against control circuit malfunction while maintaining ease of circuit connection through straightforward integration
Data Source
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AI summary
It is an object of the invention to provide a technique for preventing power tool from being operated by a malfunction of the control circuit. A representative driving power tool includes a movable element, a drive unit to drive the movable element, an actuation circuit to actuate the drive unit, a control circuit and an operation switch that outputs an operation signal. The control circuit outputs a control signal when the operation signal for instructing driving of the movable element is outputted from the operation switch. The actuation circuit actuates the drive unit when the control signal is outputted from the control circuit. Actuation of the drive unit is blocked when the control signal outputted from the control circuit is abnormal. According to the invention, a movable element can be prevented from being moved by malfunctioning of the control circuit.