Toner Charge Measurement via Developing Current Subtraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing image forming apparatuses using two-component developers face challenges in accurately measuring toner charge amounts due to environmental fluctuations and complex print conditions, leading to issues like decreased image density, image fogging, and toner scattering.
Innovation Solution
An image forming apparatus with a control unit that calculates the toner charge amount by detecting the developing current and subtracting the carrier current from the toner current, using a reference image to estimate the toner charge based on the toner current and developing amount, thereby accurately measuring toner charge and adjusting image formation conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If prediction methods based on number of prints and environmental conditions are used to adjust toner charge amount, then image density can be maintained under simple conditions, but prediction accuracy deteriorates when number of prints, environmental fluctuation, print mode, and print rate change in a complex manner
Solution Approach 1:
The patent replaces the mechanical/prediction-based system (estimating toner charge from print counts and environmental data) with an electrical measurement system (directly measuring developing current to calculate toner charge amount). This substitution enables accurate measurement under complex varying conditions by directly detecting the electrical properties of the developing process rather than relying on predictive models.
Solution Approach 2:
The patent introduces an intermediary measurement approach by using developing current as a mediator to indirectly measure toner charge amount. Instead of directly measuring charge or relying on predictions, the system measures the developing current flowing during the development process and calculates toner charge from this intermediate electrical parameter, providing accurate results under varying conditions.
2Measurement precision
If developing current is measured to calculate toner charge amount, then measurement accuracy is improved, but device complexity increases due to additional current detecting units and calculation circuits
Solution Approach 1:
The patent makes the existing developing voltage power supply unit perform multiple functions: it not only applies developing voltage to the developer carrier but also serves as part of the current detection system by measuring the developing current. This multi-functionality reduces device complexity by eliminating the need for separate dedicated current measurement hardware while maintaining accurate toner charge measurement capability.
Solution Approach 2:
The patent merges the voltage application function and current measurement function into a single integrated system. The developing voltage power supply unit is designed to both apply voltage and detect current, combining what would traditionally be separate components into one unified device, thereby simplifying the overall system architecture while achieving accurate toner charge measurement.
3Measurement precision
If carrier current is subtracted from developing current to obtain toner current, then toner charge measurement accuracy is improved, but calculation complexity increases
Solution Approach 1:
The patent performs preliminary measurement of carrier current under conditions where no toner transfer occurs (such as during cleaning cycles or when the photoconductor surface is fully charged). This pre-measured carrier current value is then subtracted from the developing current during actual image formation to isolate the toner current component. This preliminary action simplifies the calculation by having the carrier current value ready in advance rather than requiring complex real-time separation.
Solution Approach 2:
The patent measures carrier current separately and then subtracts it from the total developing current to obtain toner current. This partial measurement approach (measuring only the carrier component separately) simplifies the overall calculation compared to attempting to directly measure toner current, while still achieving accurate results through the subtraction of the known carrier current component.
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 allows for precise estimation of toner charge, identifying carrier life and image density issues, and effectively suppressing image defects like development ghosts and transfer failures by optimizing toner concentration and voltage settings.
Implementation Method 1
The charging device charges the image carrier
Implementation Method 2
An exposing device forms an electrostatic latent image by exposing the image carrier charged by the charging device
Implementation Method 3
The developing device has a developer carrier arranged facing the image carrier and carrying a two-component developer that includes a magnetic carrier and toner, and forms a toner image by adhering the toner to the electrostatic latent image formed on the image carrier
Implementation Method 4
The current detecting unit detects a DC component of a developing current that flows when a developing voltage is applied to the developer carrier
Data Source
AI summary
Provided is an image forming apparatus having a simple configuration capable of measuring a toner current included in a developing current and accurately calculating a toner charge amount based on the measurement result. A developing device has a developer carrier that carries a two-component developer including a magnetic carrier and toner. A developing voltage power supply applies a developing voltage obtained by superimposing an AC voltage on a DC voltage on the developer carrier. A control unit estimates a toner charge amount based on a toner current calculated by subtracting a carrier current from a developing current detected by a current detecting unit when a reference image is formed during non-image formation, and a toner developing amount calculated from the density of a reference image detected by a density detecting device.