Fire Alarm Master Unit Time Division Synchronization

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Solution Overview

Problem

In automatic fire alarm systems, interference between response signals from multiple slave devices can occur due to clock generator inaccuracies, leading to potential miscommunication and incorrect recognition of fire alarms.

Innovation Solution

The system introduces a master device that synchronizes with slave devices using a time division communication method, where each slave device transmits its response signal after a unique waiting time, varying the voltage between cables, to minimize interference by ensuring response signals fall within designated reception periods.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the reception interval of the synch signal is extended to accommodate more slave devices, then the system capacity increases, but the time lag between synch signal reception and response signal transmission increases, causing signal interference

Engineering Contradiction:
Improvenumber of slave devicesVSAvoidtime lag
Core Design Contradiction:
Quantity of substanceVSLoss of time

Solution Approach 1:

The patent segments the response signal transmission process by introducing a waiting time period for each slave device before transmission. This segmentation allows multiple slave devices to transmit responses in a structured sequence rather than simultaneously, preventing interference while accommodating more devices in the system.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements periodic action by requiring slave devices to wait for a predetermined time period after receiving the synch signal before transmitting their response signals. This periodic timing structure ensures that responses from multiple slave devices are transmitted in an organized manner, preventing overlap and interference while allowing the system to scale to more devices.

Inventive Principle:
Principle #19Periodic action

2Ease of manufacture

If slave devices with low accuracy clock generators are used, then device cost decreases, but signal transmission timing precision deteriorates, causing response signal interference

Engineering Contradiction:
Improvedevice costVSAvoidtiming precision
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent applies preliminary anti-action by proactively introducing a waiting time period that compensates for potential timing errors from low-accuracy clock generators. This pre-planned time buffer prevents timing conflicts before they occur, allowing the system to use cheaper clock generators while maintaining reliable signal transmission.

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

The waiting time period acts as an intermediary element between the synch signal reception and response signal transmission. This intermediary time buffer absorbs timing variations caused by low-accuracy clock generators, preventing direct timing conflicts between multiple slave devices while allowing them to use cost-effective components.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Productivity

If multiple slave devices transmit response signals simultaneously, then communication efficiency increases, but signal interference occurs, leading to miscommunication

Engineering Contradiction:
Improvecommunication efficiencyVSAvoidsignal accuracy
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary action by having slave devices prepare their response signals during the waiting time period after receiving the synch signal. This preliminary preparation ensures that when transmission occurs, each device is ready to transmit at its designated time without conflict, maintaining both efficiency and reliability.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements dynamics by allowing the system to adapt its communication timing based on the number of slave devices and their individual waiting time requirements. This dynamic timing structure enables the system to maintain efficient communication while preventing interference, as each slave device can transmit at an optimized time based on system conditions.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3349196B1Master unit for automatic fire alarm system and automatic fire alarm system
Publication Date: 2019.12.04 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD
  • EP3349196B1 patent drawingFigure 1
  • EP3349196B1 patent drawingFigure 2
  • EP3349196B1 patent drawingFigure 3

AI summary

An object of the present invention is to provide an automatic fire alarm system master device and automatic fire alarm system that would reduce the chances of causing interference between response signals transmitted from a plurality of slave devices and also provide an automatic fire alarm system slave device configured to transmit a response signal to cause interference much less frequently. A master device (20) according to the present invention includes a transmitter (24), a transmission controller (274), a receiver (23), and a reception controller (273). The transmission controller (274) makes the transmitter (24) transmit a synch signal every time a predetermined amount of time passes. Sixteen slave devices (10) are connected to a pair of cables (51, 52). The slave devices (10) transmit their respective response signals after their respective waiting times, varying their length from one slave device (10) to another, have passed since reception of the synch signal. The reception controller (273) makes the receiver (23) receive the respective response signals from the slave devices (10) during their respective reception periods after their respective waiting times have passed since transmission of the synch signal by the transmitter (24). The predetermined amount of time is long enough to allow the response signals to fall within their respective reception periods.