Facsimile Line Status Detection Using Delayed Voltage Monitoring
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Solution Overview
Problem
Facsimile devices incorrectly judge whether an external telephone has released a public line due to interference from digital service units like PBX or terminal adapters, leading to erroneous busy state indications.
Innovation Solution
A facsimile device configuration that includes a voltage detector, a telephone status monitoring unit, and a monitoring operation control unit to delay activation of the monitoring unit until a predetermined time after the facsimile circuit releases the public line, preventing erroneous judgments by digital service unit interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the facsimile device immediately monitors the public line voltage after releasing the line to detect external telephone status, then the response speed is improved, but erroneous judgment occurs due to intermediate voltage states caused by digital service units
Solution Approach 1:
The facsimile device performs a preliminary action by waiting for a predetermined time period after releasing the public line before monitoring the voltage to detect external telephone status. This preliminary waiting period allows the voltage to stabilize and avoids detecting intermediate voltage states that would cause erroneous judgment, thus resolving the contradiction between fast response and accurate detection.
2Measurement precision
If the facsimile device monitors the public line voltage continuously to detect external telephone status, then the detection precision is improved, but false busy state indications occur due to voltage interference from digital service units
Solution Approach 1:
The facsimile device applies preliminary action by introducing a predetermined waiting period after line release before initiating voltage monitoring. This ensures that the voltage has stabilized and intermediate states have disappeared, allowing continuous monitoring to accurately detect the external telephone status without false busy state indications.
Solution Approach 2:
The predetermined time period acts as an intermediary element between line release and voltage monitoring. This time interval mediates the transition by allowing the digital service unit to complete its voltage stabilization process, thereby enabling accurate detection without interference from intermediate voltage states.
3Productivity
If the facsimile device releases the public line immediately after communication to improve line availability, then the productivity is improved, but erroneous status detection occurs due to lingering intermediate voltage
Solution Approach 1:
The facsimile device releases the public line immediately after communication to improve line availability and productivity. The predetermined waiting period is then applied as a preliminary action before status detection, allowing the voltage to stabilize without delaying the line release, thus maintaining both high productivity and accurate detection.
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
Prevents incorrect judgments about the external telephone's line status, ensuring accurate detection of the telephone's on-hook or off-hook state and preventing false busy state messages.
Implementation Method 1
a voltage detector that detects a voltage of the public line
Data Source
AI summary
A facsimile device connected to a public line in parallel with an external telephone is provided. The facsimile device includes a facsimile circuit configured to send and receive image data through the public line, a voltage detector that detects a voltage of the public line, a telephone status monitoring unit configured to judge whether the external telephone closes the public line based on the voltage of the public line detected by the voltage detector and a reference voltage, a monitoring operation control unit configured to keep the telephone status monitoring unit in an inactive state until a predetermined time elapses from a time when the facsimile circuit releases the public line, and to activate the telephone status monitoring unit if the predetermined time elapses from the time when the facsimile circuit releases the public line.