Elevator Call Button Circuit Using PWM and Resistance Sensing
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Solution Overview
Problem
Elevator systems in high-rise or ultra-high-rise buildings face challenges with wire management due to the large number of buttons, leading to complex layouts and increased costs, especially in devices like Car Operation Panels (COP) and Hall Button Panels (HBP), where multiple wires are required for light-emitting control and status monitoring.
Innovation Solution
A device with button units featuring a switching element and a variable resistance circuit, utilizing a control unit to determine button switch states via resistance values and apply pulse width modulation signals with varying duty cycles to control a display element, reducing the number of wires needed by using a two-wire setup for each button.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If multiple buttons are equipped with multiple wires for light-emitting control and status monitoring, then the button functionality is complete, but the wire layout becomes complex and the cost of wire harnesses increases
Solution Approach 1:
The patent combines the light-emitting control function and button status monitoring function into a single wire connection. The control unit sends a first signal through the wire to control the display element's light emission, and simultaneously monitors the button's switching state by detecting the second signal (voltage change) on the same wire. This merging of functions reduces the number of wires from multiple separate connections to a single shared communication line, directly resolving the wire layout complexity issue.
Solution Approach 2:
The single wire connection is designed to perform multiple functions simultaneously: it serves as both a control signal transmission line for the display element and a status monitoring line for the button switch. The control unit can differentiate between the first signal (for light control) and the second signal (for status monitoring) based on signal characteristics, enabling one wire to replace what would traditionally require multiple dedicated wires.
2Adaptability or versatility
If the number of buttons is increased to accommodate high-rise or ultra-high-rise buildings, then the elevator serving capacity is improved, but the wire layout difficulty and wire harness cost increase
Solution Approach 1:
The patent implements a universal communication protocol where a single wire connection between the control unit and each button unit handles both control and monitoring functions. This universal approach allows the system to scale to any number of buttons (whether for high-rise or ultra-high-rise buildings) without proportionally increasing wire complexity, as each button unit uses the same single-wire interface regardless of the total number of buttons in the system.
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 simplifies wiring and reduces manufacturing costs by minimizing the number of wires required, while providing clear visual feedback on button states through adjustable light emission, thus enhancing the efficiency and cost-effectiveness of elevator input devices.
Implementation Method 1
the display element is a light-emitting diode
Data Source
AI summary
A device for inputting an elevator calling command and an elevator control system including the device. A device for inputting an elevator calling includes one or more button units, each of the button units including a switching element and a variable resistance circuit coupled with the switching element. The variable resistance circuit includes 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 includes 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.