Rotary Switch Shaft Integrating LED for Illuminated Indication
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Solution Overview
Problem
Existing electromechanical controls for appliances like washing machines are difficult to operate in low-light settings due to inadequate illumination of the control knob's setting indicia.
Innovation Solution
A light emitting diode (LED) is integrated into the operator shaft of the control knob, with sliding contacts providing power and alignment to enhance light efficiency, allowing for direct illumination of the knob's indicia, and includes features like a fracture plane to protect users from line voltage in case of damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If an LED is placed at the distal end of the operator shaft to provide illumination, then the illumination intensity and efficiency are improved, but the complexity of the control structure increases
Solution Approach 1:
The patent combines the LED light source with the operator shaft by positioning the LED at the distal end of the shaft, integrating two separate functions (illumination and mechanical operation) into a single unified structure. This merging approach improves illumination efficiency while minimizing additional structural complexity.
Solution Approach 2:
The LED is nested within the operator shaft structure, specifically positioned at the distal end where it can utilize the shaft's existing geometry and mounting features. This nesting approach allows the illumination component to be housed within the mechanical component, reducing overall space requirements and simplifying the control structure.
2Use of energy by moving object
If sliding contacts are used to provide power to the LED, then energy efficiency is improved, but the reliability of the electrical connection deteriorates
Solution Approach 1:
The patent employs sliding contacts that maintain continuous electrical connection with the rotating shaft, providing a buffered connection that compensates for rotational movement and potential misalignment. This beforehand cushioning approach ensures reliable power delivery to the LED while maintaining energy efficiency through the sliding contact mechanism.
3Illumination intensity
If the LED is positioned closer to the knob for better alignment with the pointer, then light efficiency is improved, but the exposure to line voltage increases
Solution Approach 1:
The patent introduces an intermediary fracture plane between the LED and the line voltage contacts. This fracture plane acts as a safety barrier that separates the high-voltage electrical components from the low-voltage illumination components. In normal operation, the fracture plane remains intact, allowing the LED to be positioned close to the knob for optimal light efficiency while protecting against line voltage exposure.
Solution Approach 2:
The operator shaft is segmented into distinct electrical zones by the fracture plane, separating the line voltage contacts from the LED power supply. This segmentation creates isolated electrical domains where high voltage and low voltage coexist safely, enabling the LED to be positioned near the knob without increasing exposure to hazardous voltages.
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 solution provides improved illumination of the control knob's settings in low-light conditions while ensuring user safety by reducing exposure to hazardous voltages in case of damage, making the control more intuitive and user-friendly.
Implementation Method 1
A light emitting diode (LED) is integrated into the operator shaft of the control knob
Data Source
AI summary
A shaft of a rotary switch, for example, useful as a control for an appliance, such as a washing machine, incorporates an LED at the end of the shaft and projecting light laterally from the shaft to provide an indication of the rotary position of the corresponding knob with respect to printed indicia on a console. The LED may be powered by slip rings incorporated into the rotary switch and communicating directly with line power as controlled by the limiting resistor and the shaft may include a controlled breakage feature providing LED conductors that are recessed within the shaft in the event of shaft breakage to reduce the chance of operator contact with line voltage.