Capacitive Sensor Relative Capacitance Measurement
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Solution Overview
Problem
Existing capacitive sensors in image forming apparatuses require factory calibration and non-volatile memory to determine waste toner levels, which limits their effectiveness and yield due to large tolerances in capacitance values.
Innovation Solution
A method that measures voltage intervals to calculate relative changes in capacitance, eliminating the need for initial calibration values by comparing these changes with threshold values and counting printed pages to determine toner levels, allowing for accurate detection of nearly full and full toner conditions without factory calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a capacitive sensor uses absolute capacitance values to determine waste toner levels, then the sensor can operate without non-volatile memory, but the large tolerance in capacitance values greatly decreases the expected yield of the waste toner box
Solution Approach 1:
The patent changes the measurement parameter from absolute capacitance values to relative capacitance changes (delta capacitance). By measuring the change in capacitance as waste toner accumulates between the capacitor plates, rather than relying on absolute values, the system achieves accurate measurement without requiring precise manufacturing tolerances or calibration storage.
2Measurement precision
If a capacitive sensor requires factory calibration and non-volatile memory storage, then measurement precision can be maintained, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts and eliminates the non-volatile memory component from the sensor system. By using relative capacitance change measurements, the system removes the need to store calibration values in memory, simplifying the device while maintaining measurement precision through differential measurement techniques.
3Productivity
If the waste toner box capacity is increased to maximize productivity, then more waste toner can be collected, but the sensor must accurately detect full condition over a larger range
Solution Approach 1:
The patent implements continuous monitoring of capacitance changes as waste toner accumulates in the box. By continuously measuring the relative change in capacitance rather than taking discrete snapshots, the system maintains accurate detection of the full condition across the entire capacity range, enabling larger box capacity without sacrificing measurement 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 approach enables reliable detection of waste toner levels without factory calibration, maximizing the capacity of the waste toner box and preventing damage to imaging apparatuses by accurately determining when the toner box is nearly full or full.
Implementation Method 1
Another sensor used in the prior system is a capacitive sensor that has a capacitor, the capacitance of the capacitor changes as the medium between plates of the capacitor changes from air to waste toner.
Data Source
AI summary
A capacitive sensor for sensing amount of waste toner in a waste toner box of an imaging apparatus includes a capacitor that has a pair of separated plates disposed within the interior of the waste toner box. The capacitance of the capacitor changes with the amount of toner in between the plates of the capacitor. A sensor circuitry is connected to the plates of the waste toner box that measure the capacitance of the capacitor as a voltage value. This voltage value is provided to a controller that determines a relative change in the capacitance value by determining a change in capacitance of the capacitor with respect to a number of pages printed by the imaging apparatus. The controller then determines the state of the waste toner box based on this relative change in capacitance.