Toner Charging Amount Acquisition via AC Frequency Response
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Solution Overview
Problem
Conventional image forming apparatuses face challenges in accurately predicting toner charging amounts due to complex changes in printing conditions, leading to issues like decreased image density, toner fogging, and increased toner flying, which existing predictive techniques struggle to address effectively.
Innovation Solution
The image forming apparatus includes a charging device, an exposing device, a developing device, a toner density detecting unit, a transfer unit, a development bias applying unit, and a storage unit that measures and adjusts toner charging amounts by changing the frequency of the alternating current voltage of the development bias, using reference information to calculate the toner charging amount based on detected density changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional prediction techniques are used to adjust toner density, development bias, and other parameters, then image density can be maintained under simple conditions, but prediction accuracy deteriorates when multiple conditions change compositively
Solution Approach 1:
The invention changes the measurement approach from predicting charging amount under various conditions to directly measuring it through frequency response characteristics. By measuring the tilt value from the relationship between AC voltage frequency changes and toner image density changes, the system obtains accurate charging amount data regardless of composite condition changes, eliminating the prediction accuracy problem.
2Measurement precision
If surface potential sensors or current measurement devices are added to measure charging amount directly, then measurement precision improves, but device complexity increases
Solution Approach 1:
Instead of directly measuring charging amount with specialized sensors, the invention uses the existing density detection system to measure toner image density. By correlating density changes with frequency changes, it indirectly obtains charging amount information through a measurement copy approach, avoiding the need for complex direct measurement devices.
Solution Approach 2:
The invention introduces frequency response characteristics as an intermediary measurement parameter. Rather than directly measuring charging amount or surface potential, it measures the relationship between AC voltage frequency and toner image density, using this intermediate response to derive charging amount information without complex sensors.
3Reliability
If conventional techniques are used to suppress toner flying and maintain image density, then image quality can be maintained under stable conditions, but toner flying increases and image density decreases when developer deteriorates
Solution Approach 1:
The invention implements a feedback mechanism where the measured charging amount (derived from frequency response) is continuously monitored and used to adjust development bias and other parameters. This closed-loop control automatically compensates for developer deterioration, maintaining image quality and suppressing toner flying without manual intervention.
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 allows for accurate prediction and adjustment of toner charging amounts, optimizing image density and reducing toner flying, thereby maintaining satisfactory image quality across varying printing conditions without the need for surface potential sensors or current measurements.
Implementation Method 1
a charging device that charges the image carrier to a predetermine charging potential
Implementation Method 2
an exposing device that exposes the surface of the image carrier charged to the charging potential, based on predetermined image information so as to form the electrostatic latent image
Implementation Method 3
a developing device that is disposed in a predetermined development nip portion in the rotational direction downstream with respect to the exposing device so as to oppose the image carrier. The developing device includes a developing roller that is rotated, carries developer including toner and carrier on a peripheral surface of the developing roller, and supplies the toner to the image carrier so as to form the toner image
Implementation Method 4
a transfer unit that transfers the toner image carried on the image carrier to a sheet
Data Source
AI summary
An image forming apparatus includes a storage unit and a charging amount acquisition unit. The charging amount acquisition unit forms a measurement toner image on the image carrier while changing the frequency of the alternating current voltage of the development bias with the potential difference in the direct current voltage between the developing roller and the image carrier being kept constant, acquires a tilt of a measurement straight line representing a relationship between the change amount of the frequency and the density change amount of the measurement toner image, based on the change amount of the frequency and a result of detecting density of the measurement toner image in the density detecting unit, and acquires a charging amount of the toner included in the measurement toner image formed on the image carrier based on the acquired tilt of the measurement straight line and the reference information in the storage unit according to the toner density detected by the toner density detecting unit.