Capacitive Hand Dryer Sensing to Prevent False Triggering
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Solution Overview
Problem
Conventional hand dryers face issues with untimely triggering and complex installation due to the positioning of photoelectric sensors, which require a transparent part for light beam detection, leading to hygiene, sealing, and cost challenges.
Innovation Solution
A hand dryer design utilizing a capacitive proximity detector positioned behind an opaque outer part with a detection zone extending through and opposite this part, and a metal barrier at the front wall to limit the detection zone, eliminating the need for a transparent component and simplifying the structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a photoelectric sensor is used for proximity detection, then detection function is achieved, but a transparent part is required which causes installation complexity, sealing problems, and hygiene issues
Solution Approach 1:
The patent extracts the transparent part from the device structure by using a capacitive proximity detector that can detect through opaque materials. This eliminates the window component entirely, removing the associated sealing joints and transparency requirements while maintaining the proximity detection function.
Solution Approach 2:
The patent replaces the optical detection system (photoelectric sensor requiring light transmission through transparent material) with a capacitive detection system that works through opaque materials. This substitution eliminates the need for transparent components and their associated sealing and hygiene problems.
2Reliability
If a transparent part is used for photoelectric sensor positioning, then light beam detection is enabled, but cleaning frequency increases and hygiene problems arise
Solution Approach 1:
The transparent part is completely removed from the device. The capacitive proximity detector is positioned behind the opaque outer wall and detects changes in capacitance through the wall material, eliminating the window that would require frequent cleaning and maintenance.
Solution Approach 2:
The detection function is copied from an optical system to a capacitive system that works through the same opaque material, allowing the outer wall to serve both structural and detection transmission purposes without requiring transparency.
3Reliability
If the detection zone extends over the front of the drying device, then proximity detection is achieved, but untimely triggering occurs
Solution Approach 1:
The patent applies local quality by using a metal barrier part at the front wall to locally limit the capacitive field. This creates a defined detection zone only in specific areas where hand placement occurs, preventing premature triggering while maintaining detection sensitivity in the intended zones.
Solution Approach 2:
The metal barrier part acts as an intermediary element that shapes and confines the capacitive detection field. It prevents the field from extending too far forward, thereby avoiding untimely triggering while allowing detection to occur at the appropriate location when hands are placed in the drying zone.
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 detection accuracy while avoiding untimely triggering and reduces manufacturing and maintenance costs by eliminating the need for a transparent part, resulting in a more practical and hygienic hand dryer.
Implementation Method 1
a capacitive proximity detector which generates from a detection zone for the operation of the means for producing the air flow during the presence of the hands of the user in this detection zone
Data Source
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AI summary
The present invention relates to a hand-dryer device (1) including: (i) a means (16) for producing an air flow, (ii) at least one nozzle (15), which is connected to said air-flow-producing means (16), for projecting an air jet capable of drying the hands of a user within a drying area (4), and (iii) a means (17) for controlling said air-flow-producing means (16), comprising at least one capacitive proximity sensor (19) provided with a detection area (Z), said control means (17) being intended to activate the operation of said air-flow-producing means (16) when one or both hands of the user is (are) present in said detection area (Z).