Capacitive Sensor for Passenger Conveyor Detection
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Solution Overview
Problem
Existing passenger conveyor sensing systems are costly and inefficient due to the need for multiple sensors along the length of the conveyor, increasing expenses and maintenance requirements as the conveyor length increases.
Innovation Solution
A capacitive sensing system using a driving circuit, capacitive sensor, and controller to detect changes in capacitance caused by a person's presence, allowing for adjustment of the conveyor's operation mode through an oscillating drive signal and electric field generation between electrodes on balustrades or within the machine room.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple sensors are used along the length of the passenger conveyor, then detection reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges multiple sensing functions into a single capacitive sensor system. Instead of using multiple separate sensors (optical, infrared, piezoelectric, or RF) along the conveyor length, the invention uses one capacitive sensor with electrodes positioned on opposite sides of the conveyor to detect passengers throughout the entire length, thereby reducing device complexity while maintaining detection reliability
Solution Approach 2:
The capacitive sensor serves multiple functions: it detects passenger presence, determines passenger position, and triggers conveyor operation throughout its length. This single sensor system replaces multiple specialized sensors, achieving universal functionality that reduces both device complexity and cost while maintaining comprehensive detection capability
2Measurement precision
If multiple sensors are installed along the passenger conveyor, then detection precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent combines multiple sensing functions into a single capacitive sensor system, reducing the number of components that need to be manufactured and installed. This merging approach maintains detection precision through the capacitive field's ability to detect passengers at various positions while significantly reducing manufacturing cost compared to installing multiple separate sensors throughout the conveyor length
Solution Approach 2:
The capacitive field created by the electrodes acts as a virtual sensing network that covers the entire conveyor length without requiring physical sensors at each position. This field-based approach provides continuous detection coverage and precise passenger position detection while avoiding the high manufacturing and installation costs of multiple discrete sensors
3Reliability
If multiple sensors are used to detect passengers, then safety is improved, but maintenance requirements increase
Solution Approach 1:
The patent merges multiple sensing functions into a single capacitive sensor system with electrodes on opposite sides of the conveyor. This consolidation maintains safety by providing comprehensive passenger detection throughout the conveyor length while reducing maintenance requirements from what would be needed for multiple separate sensors distributed along the entire conveyor
4Adaptability or versatility
If sensors are installed throughout the length of the passenger conveyor, then detection capability is improved, but device complexity increases
Solution Approach 1:
The patent transitions from a one-dimensional array of discrete sensors along the conveyor length to a three-dimensional capacitive field between electrodes positioned on opposite sides of the conveyor. This dimensional change allows the system to detect passengers at any position along the conveyor without requiring multiple discrete sensing points, thereby improving detection capability while reducing device complexity
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
Enables efficient and cost-effective detection of passengers on the conveyor, allowing for controlled operation modes such as starting, slowing, or stopping, while reducing the need for extensive sensor installations, thereby improving safety and energy efficiency.
Implementation Method 1
a capacitive sensor having a first electrode configured to produce an electric field toward a second electrode in response to the oscillating drive signal
Implementation Method 2
a detection circuit connected to the capacitive sensor to sense changes in capacitance of the capacitive sensor
Data Source
Figure 1
Figure 2
Figure 3A~3F
AI summary
A system for detecting a person relative to a passenger conveyor includes a driving circuit for supplying an oscillating drive signal to a first electrode of a capacitive sensor configured to produce an electric field toward a second electrode in response to the oscillating drive signal. A detection circuit is connected to the capacitive sensor, and produces an output as a function of the capacitance of the capacitive sensor, such that the detection circuit senses a change in capacitance of the capacitive sensor, such as when a person enters the electric field between the first and second electrodes. A controller is responsive to the change in capacitance sensed by the detection circuit to selectively adjust an operation mode of the passenger conveyor.