Optical Pushbutton Faceplate Sensing With Wider Assembly Tolerance
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Solution Overview
Problem
Conventional pushbuttons actuated by force, especially capacitive, inductive, or piezoelectric types, require high manufacturing and assembly accuracy with tight tolerance ranges, and often necessitate additional insulation or transparent materials, leading to reliability issues and increased susceptibility to errors.
Innovation Solution
An operating device with a cover plate that is partly elastically deformable, equipped with a transmitter for emitting electromagnetic radiation and a receiver for spatially resolving the reflection, allowing reliable actuation detection through minimal deformations, thereby increasing tolerance ranges and reducing the need for calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional pushbuttons (capacitive, inductive, piezoelectric) are used, then actuation detection is possible, but manufacturing and assembly accuracy requirements are high with tight tolerance ranges
Solution Approach 1:
The patent replaces conventional capacitive, inductive, or piezoelectric sensing mechanisms with an optical measurement system. A transmitter emits radiation toward the operating portion, and a receiver detects changes in the reflected radiation pattern when the operating portion deforms under actuation force. This optical substitution eliminates the need for tight electrical tolerances and insulation measures, resolving the contradiction between detection precision and manufacturing precision requirements.
2Measurement precision
If contact and proximity sensitive pushbuttons are used, then actuation detection is possible, but additional insulation measures are required for metallic operating faceplates
Solution Approach 1:
The optical sensing system replaces electrical sensing fields, eliminating the need for insulation between the metallic operating faceplate and underlying components. Since the measurement is based on optical reflection rather than electrical field interaction, metallic faceplates can be used without additional insulation layers, simplifying the device structure while maintaining detection capability.
3Measurement precision
If optical sensor systems are used, then actuation detection is possible, but transparent materials or perforations are required for the operating faceplate
Solution Approach 1:
Instead of transmitting radiation through the operating faceplate from the rear (which would require transparent materials or perforations), the system inverts the approach by emitting radiation from the front side and detecting the reflected radiation. The transmitter and receiver are positioned to detect changes in the reflection pattern caused by surface deformation, allowing the use of opaque materials without compromising detection functionality.
4Reliability
If conventional pushbuttons with tight tolerances are used, then actuation detection is reliable, but susceptibility to errors increases and calibration is needed
Solution Approach 1:
The optical system measures actuation through changes in the reflection pattern of radiation, which are caused by surface deformation. This approach is less susceptible to environmental errors such as humidity, temperature drift, and electrical interference that affect conventional sensing methods. The system evaluates the spatial distribution of reflected radiation rather than relying on absolute threshold values, reducing error susceptibility while maintaining reliable detection.
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 enhances the reliability and reduces manufacturing complexity by detecting actuations based on relative changes in radiation reflection, allowing for increased tolerance in component assembly and eliminating the need for calibration, while maintaining functionality across various materials and dimensions.
Implementation Method 1
at least one transmitter for emitting electromagnetic radiation
Implementation Method 2
the operating portion... at least partly reflects the radiation emitted by the at least one transmitter
Implementation Method 3
at least one receiver for registering electromagnetic radiation
Implementation Method 4
The operating portion of the cover plate is configured in such a way that it is at least partly elastically deformable and/or movable by an action of force
Data Source
AI summary
An operating device, in particular for electronic household appliances, includes a cover plate with an operating portion, a transmitter for emitting electromagnetic radiation, a receiver for registering electromagnetic radiation, and control electronics for evaluating measurement signals produced by the receiver. The operating portion is at least partly elastically deformable and/or movable by an action of force from the direction of a user side of the cover plate and it at least partly reflects the radiation emitted by the transmitter. The receiver is disposed and/or configured in such a way that it facilitates a spatially resolved registration of the radiation reflected by the operating portion in such a way that the control electronics can detect an actuation of the operating portion in a manner dependent on a registration location of the reflected radiation. An electronic household appliance having at least one operating device is also provided.