Magnetic Reed Switch Toner Level Detection Noise Filtering
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Solution Overview
Problem
In full-color image forming apparatuses, the proximity of motors to magnetic reed switches causes interference, leading to incorrect detection of toner levels in buffers, which hinders appropriate toner supply control.
Innovation Solution
Implementing a detection unit that samples magnetic reed switch signals at intervals equal to one-Nth of the motor's control pulse signal period, allowing determination of whether signals indicate toner shortage or motor noise, using signals from the last N periods to differentiate between the two.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a magnetic reed switch is used for detecting toner level in full-color image forming apparatus, then production cost is reduced, but the motor's magnetic field interference causes incorrect detection
Solution Approach 1:
The detection unit samples the magnetic reed switch signal periodically at intervals equal to one-Nth of the motor's control pulse period. This periodic sampling allows the system to distinguish between signals caused by toner level changes and those caused by motor operation, resolving the interference issue while maintaining cost-effectiveness
Solution Approach 2:
The determination unit uses feedback from multiple signal samples taken at different periods to determine whether toner supply is needed. By comparing signals across N periods, the system can identify genuine toner level changes versus motor-induced noise, improving detection reliability without adding significant cost
2Volume of moving object
If the motor is positioned close to the magnetic reed switch to save space, then device compactness is improved, but magnetic field interference increases
Solution Approach 1:
By sampling the magnetic reed switch signal at specific periodic intervals (one-Nth of the motor pulse period), the system can filter out magnetic interference from the motor while maintaining close positioning for compactness
Solution Approach 2:
The system performs preliminary sampling of the magnetic reed switch signal at multiple periods before making a determination. This preliminary action allows the system to anticipate and filter out motor-induced magnetic interference before it affects the toner level detection accuracy
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 approach prevents erroneous toner supply by accurately distinguishing between toner level changes and motor-induced noise, ensuring toner is replenished only when necessary, thus maintaining optimal buffer levels.
Implementation Method 1
The magnetic reed switch is turned ON and OFF in response to a change in magnetic field (i.e. magnetic variation) occurred in a sensing range
Implementation Method 2
As the liquid level of the toner is lowered, the detection plate along with the magnet moves down. At this time, the magnet brings about the change in the magnetic field
Data Source
AI summary
An image forming apparatus includes a buffer configured to temporarily store in the buffer toner supplied from a toner cartridge and to be fed to a developing unit; a magnetic reed switch configured to sense magnet variation occurring in a sensing range and sequentially output signals each indicating a result of the sensing; a toner level indicator plate disposed within the buffer to swing up and down about a fixed edge in response to a change in a level of the toner that remains in the buffer, the toner level indicator plate having a magnet on a free edge thereof, the magnet being made to reach the sensing range in a state where the toner level indicator plate has swung down.