Power Tool Rotational Handle Control via Optical Sensor
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Solution Overview
Problem
Current power tools require users to linearly move their fingers to control rotational motion, making it difficult to directly compare trigger travel to output rotation and adjust speed quickly for finer control.
Innovation Solution
The power tool incorporates a handle connected to a potentiometer or sensor that allows rotational movement, enabling users to select rotational direction and speed by rotating the handle, and includes a trigger assembly with multiple degrees of freedom and force-sensing resistors for tactile feedback, along with a swipe pad or pressure sensing pads for intuitive control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a digital switch or analog trigger switch is used to control tool output, then the tool can be turned on and off or deliver variable power, but the user's linear finger travel makes it difficult to directly compare trigger travel to output rotation and achieve quick speed adjustments
Solution Approach 1:
The patent replaces the traditional mechanical trigger switch with an optical sensor system. A light source and light receiver detect the rotational position of a coded disk attached to the output shaft, converting mechanical rotation into electrical signals for speed control. This substitution enables direct optical measurement of output rotation, resolving the difficulty of comparing trigger travel to output rotation.
Solution Approach 2:
The patent implements a feedback mechanism where the optical sensor detects the actual output rotation through the coded disk and provides this information to the control system. This feedback loop allows the system to compare the desired speed (from trigger position) with the actual output speed, enabling precise speed adjustments and resolving the measurement comparison difficulty.
2Speed
If a traditional trigger switch is used, then the tool delivers power based on trigger travel, but the user cannot make quick speed adjustments for finer control
Solution Approach 1:
The patent replaces the mechanical trigger switch with an optical encoder system that directly measures output shaft rotation. This substitution provides precise, real-time feedback on actual output speed, enabling the microprocessor to make quick, accurate speed adjustments for finer control that was not achievable with traditional mechanical triggers.
Solution Approach 2:
The patent implements dynamic speed control where the microprocessor continuously adjusts motor power based on real-time feedback from the optical sensor. This dynamic adjustment capability allows for quick speed changes and fine control, transforming the static trigger-based control into a responsive, adaptive system.
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
This design enhances user control by allowing direct comparison of handle rotation to output rotation, enabling precise speed adjustments and operational inputs, improving user interface efficiency and ease of use.
Implementation Method 1
a light source and a light receiver for detecting a rotational position of the output shaft
Implementation Method 2
force-sensing resistors for tactile feedback
Data Source
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AI summary
A power tool (10) comprising a housing (12), a motor (14) disposed in the housing, a tool holder (22) driven by the motor, a control circuit for controlling the motor, a rotary input rotatable relative to the housing, and a rotational sensor for sensing the rotational position of the rotary input relative to the housing. The rotary input can be a thumbwheel or a handle (28) that rotates relative to the housing (12). The control circuit receives input from the rotational sensor for controlling motor speed, rotational direction, etc. Other user interface mechanisms are disclosed as well.