Sheet Conveyance Basis Weight Estimation via Capacitance Subtraction
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Solution Overview
Problem
Existing techniques for estimating the basis weight of sheets in image forming apparatuses are susceptible to surrounding environmental variations, such as temperature and humidity, leading to inaccurate measurements.
Innovation Solution
A sheet conveying apparatus that uses a capacitance detector to measure capacitance both when a sheet is not passing through a detection region and when it is, allowing for the subtraction of environmental influences, thereby accurately estimating the basis weight by calculating the difference in capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitance sensor is used to estimate basis weight of sheet, then basis weight estimation is enabled, but estimation accuracy deteriorates due to surrounding environmental variations
Solution Approach 1:
The system performs preliminary capacitance measurement in a state where no sheet passes through the detection region to establish a baseline value that includes environmental influences. This preliminary action allows the system to later subtract these environmental effects from the measurement taken when a sheet is present, thereby isolating the sheet's capacitance contribution and improving basis weight estimation accuracy.
Solution Approach 2:
The system continuously monitors capacitance values and uses the difference between measurements (with and without sheet) to dynamically adjust and refine the basis weight estimation. By comparing the capacitance measured when a sheet is present against the baseline environmental capacitance, the system creates a feedback mechanism that compensates for environmental variations and maintains accurate measurements.
2Device complexity
If capacitance measurement is performed only when sheet passes through detection region, then measurement is simplified, but environmental influences cannot be removed
Solution Approach 1:
The system performs an additional preliminary measurement in the absence of a sheet to establish an environmental baseline. This preliminary action adds minimal complexity to the measurement process but enables the removal of environmental influences, significantly improving measurement precision through simple subtraction of the baseline value from the sheet-present measurement.
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 method enables precise estimation of the basis weight of sheets, reducing environmental variations' impact and improving printing accuracy by setting optimal control parameters like sheet feeding speed and fixing temperature.
Implementation Method 1
an estimation method using a capacitance sensor has been proposed. This estimation method is the application of the principle that the capacitance of the sheet correlates with the basis weight of the sheet
Implementation Method 2
a detector that detects capacitance in a predetermined detection region in the conveyance path; and a basis weight identifier that identifies a basis weight of the sheet on the basis of first capacitance detected by the detector while the sheet does not pass through the detection region and second capacitance detected by the detector while the sheet passes through the detection region
Data Source
AI summary
A sheet conveying apparatus capable of conveying a sheet as a conveyance target in a conveyance path includes a detector that detects capacitance in a predetermined detection region in the conveyance path; and a basis weight identifier that identifies a basis weight of the sheet as the conveyance target on the basis of first capacitance detected by the detector while the sheet as the conveyance target does not pass through the detection region and second capacitance detected by the detector while the sheet as the conveyance target passes through the detection region.