Contactless Rotary Pull Switch With Magnetic Position Sensing
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Solution Overview
Problem
Existing contactless rotary pull switches for vehicle lighting and other applications face limitations in discerning distinct switching positions and suffer from increased cost and complexity due to the placement of circuit boards and LEDs, which affects durability and lighting efficiency.
Innovation Solution
A contactless rotary pull switch design that utilizes magnetic sensing for robust detection of both rotational and pull positions, with a multi-pole rotational magnet maintained in a fixed axial position and separate pull magnets, along with a vane member to interrupt the magnetic field, allowing for distinct position identification and efficient backlighting through LEDs positioned adjacent the switch face.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single magnet or arrangement of magnets is used with sensors to determine both rotational position and pull position, then the switch can operate contactlessly, but the variations in magnetic field strength are not great enough to discern a distinct switching position
Solution Approach 1:
The patent divides the magnetic sensing system into two separate subsystems: one for rotational position detection and one for pull position detection. Each subsystem uses dedicated magnets and sensors, ensuring that each function has sufficient magnetic field variation for reliable detection without interference from the other function.
Solution Approach 2:
The patent introduces a non-ferrous arm member as an intermediary element that mechanically couples the rotary shaft to the pull position magnet assembly. This arm member transmits the pull motion to the magnets without being affected by magnetic fields, enabling reliable pull position detection while maintaining contactless operation.
2Ease of manufacture
If the circuit board and LEDs are located at the back portion of the switch module, then the switch structure is simplified, but optical fibers or light pipes are necessary for transmitting light, increasing cost and complexity
Solution Approach 1:
The patent merges the circuit board and LED assembly with the front face of the switch module, eliminating the need for separate light transmission mechanisms. The LEDs are positioned directly adjacent to the symbols on the face, allowing light to illuminate the symbols directly without requiring optical fibers or light pipes.
3Reliability
If mechanical contacts are used for controlling vehicle lighting functions, then the switch can provide robust switching, but the switch is not contactless, reducing durability
Solution Approach 1:
The patent replaces the mechanical contact system with a contactless magnetic sensing system. Magnets and magnetic sensors are used to detect both rotational and pull positions without physical contact, eliminating wear and tear associated with mechanical contacts while maintaining reliable switching control for vehicle lighting functions.
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
The solution provides robust sensing of rotational and pull positions, enhances durability, and achieves bright, efficient lighting with reduced complexity and cost by maintaining the magnetic field strength for rotational sensing and using a vane member for pull position detection, while ensuring waterproof construction.
Implementation Method 1
a first magnetic sensor configured to sense a magnetic field generated by the first magnet to identify a rotational position of the switch knob assembly
Implementation Method 2
at least one additional magnetic sensor configured to sense a magnetic field generated by the at least one additional magnet to identify a pull position of the switch knob assembly
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A contactless rotary pull switch includes a switch knob assembly rotatable about an axis to a plurality of rotational positions and actuatable to at least one pull position, with the switch knob assembly including a knob element and a rotational shaft fixedly coupled thereto. A rotational magnet is coupled to the rotational shaft so as to rotate therewith, and at least one pull magnet is positioned separately from the rotational magnet. A rotational sensor senses a magnetic field generated by the rotational magnet to identify a rotational position of the switch knob assembly and at least one pull sensor senses a magnetic field generated by the pull magnet(s) to identify a pull position of the switch knob assembly. A rotatable arm member selectively enables/inhibits sensing of the magnetic field generated by the pull magnet(s) by the at pull sensor(s), to identify distinct pull positions of the switch knob assembly.