Perforated Sensor Protector for Wet-Hand Dispenser Reliability
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Solution Overview
Problem
Capacitive sensors in automatic product dispensers, such as roll paper towel dispensers, often require recalibration when exposed to moisture, leading to temporary inoperability and user confusion, especially in high-use situations.
Innovation Solution
A sensor protector with a perforated surface or grid is placed in front of the sensor area to prevent liquid accumulation, featuring a ratio of 70% to 99% open area and 1% to 30% solid area, which reduces moisture collection and allows the capacitive sensor to function without recalibration, even when touched with wet hands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a capacitive sensor is used in an automatic dispenser, then hands-free operation and sanitation are improved, but the sensor becomes susceptible to moisture from wet hands causing recalibration delays
Solution Approach 1:
A sensor protector barrier is introduced as an intermediary element between the user's hands and the capacitive sensor. This barrier allows capacitive coupling to occur for hands-free operation while preventing direct contact and moisture accumulation on the sensor surface, thus maintaining reliability during wet hand conditions
2Measurement precision
If the sensor area is made accessible for capacitive sensing, then detection sensitivity is improved, but liquid accumulation on the sensor area causes recalibration
Solution Approach 1:
The sensor protector is designed with a porous or perforated structure that allows capacitive electric fields to pass through for detection while physically blocking liquid accumulation. The porous structure permits electromagnetic interaction while preventing moisture from reaching the sensor surface
3Measurement precision
If recalibration is performed when moisture is detected, then sensor accuracy is restored, but operational delays and user confusion occur
Solution Approach 1:
The sensor protector performs preliminary protection by preventing moisture from reaching the sensor in the first place, thereby eliminating the need for recalibration. This preemptive barrier stops the harmful effect before it can trigger the recalibration process, avoiding operational delays
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 sensor protector effectively prevents recalibration delays by minimizing moisture on the sensor area, ensuring continuous operation of the automatic dispenser without user confusion or downtime.
Implementation Method 1
A technology used to activate the automatic dispenser is capacitive sensing, wherein a capacitive sensor (a.k.a. capacitive displacement sensor) detects a change in capacitance when something, e.g., fingers or the hands of a user, approaches the capacitive sensor
Implementation Method 2
The sensor protector provides a protection barrier or grid in front of the sensor area. The perforations or matrix of openings in the sensor protector prevent water from the user's hands from collecting on or near the sensor area
Data Source
AI summary
A method for preventing recalibration of an automated product dispenser, a sensor protector for a product dispenser, and a product dispenser including a housing having a sensor area, a capacitive sensor adjacent a first surface of the sensor area of the housing, where the sensor has a target sensing area extending through the first surface and beyond a second surface of the housing opposite the first surface in a direction away from the first surface and a sensor protector which includes a plurality of spaced apart projections extending from the second surface in the direction away from the first surface.