Elevator Call Button Circuit With PWM Sensing to Cut Wiring
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Solution Overview
Problem
In elevator systems, particularly in high-rise or ultra-high-rise buildings, the large number of buttons in Car Operation Panels (COP) and Hall Button Panels (HBP) leads to complex wire layouts and increased costs due to the numerous wires required for light-emitting control and status monitoring, which is challenging given the limited internal space.
Innovation Solution
The implementation of a device with button units that include a switching element and a variable resistance circuit coupled in parallel with a display element, where a control unit determines the button switch state based on resistance value and applies pulse width modulation signals with different duty cycles to control the switching element, reducing the number of wires needed by integrating light-emitting diode control and status monitoring functions into a two-wire system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple buttons are equipped with separate wires for light-emitting control and status monitoring, then reliable button function control is achieved, but wire quantity and device complexity increase significantly
Solution Approach 1:
The patent combines light-emitting control and status monitoring functions into a single wire by using a variable resistance circuit where the display element and button switch share the same connection line. The control unit determines button state by detecting resistance changes in this combined circuit, eliminating the need for separate monitoring wires.
Solution Approach 2:
The single wire connecting the button switch serves multiple functions simultaneously: it provides power to the display element, controls light emission through PWM signals, and enables status monitoring through resistance detection. This multi-functional wire reduces overall wire quantity while maintaining full button functionality.
2Adaptability or versatility
If the number of buttons is increased to accommodate high-rise building requirements, then elevator service coverage is improved, but wire harness cost and internal space requirements increase
Solution Approach 1:
By merging light-emitting control and status monitoring into a single wire per button, the patent reduces the wire harness quantity proportionally with the number of buttons. This allows the system to scale to accommodate high-rise building requirements without linearly increasing wire harness complexity and cost.
3Measurement precision
If separate wires are used for each button's light-emitting control and status monitoring, then precise button state detection is achieved, but manufacturing cost increases
Solution Approach 1:
The patent achieves precise button state detection using a single wire by measuring resistance changes in the variable resistance circuit. The control unit detects whether the button is pressed by monitoring the resistance value, providing accurate state detection while reducing wire quantity and manufacturing cost.
Solution Approach 2:
The patent replaces the mechanical/electrical separation of control and monitoring wires with an electronic sensing approach. Instead of using separate physical wires for monitoring, the system uses electrical resistance measurement through the shared wire to detect button state, reducing material cost while maintaining detection precision.
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 significantly reduces the number of wires required, simplifies wiring design, and lowers manufacturing costs while maintaining effective light-emitting diode functionality and button switch state monitoring, enhancing the efficiency and cost-effectiveness of elevator control systems.
Implementation Method 1
the display element is a light-emitting diode
Data Source
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AI summary
The present application relates to elevator technology and, in particular, to a device for inputting an elevator calling command and an elevator control system comprising the device. A device for inputting an elevator calling command in accordance with an embodiment of the present application comprises one or more button units, each of the button units comprising a switching element and a variable resistance circuit coupled with the switching element. The variable resistance circuit comprises a button switch and a display element coupled in parallel, and a resistance value of the variable resistance circuit varies with a state of the button switch. The device further comprises a control unit configured to determine a state of a corresponding button switch based on the resistance value of the variable resistance circuit within each of the button units, and to apply a pulse width modulation signal having different duty cycles onto a control terminal of a corresponding switching element based on the state as determined.