Image Density Control via Patch Analysis and Toner Ratio Correction
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Solution Overview
Problem
Conventional image forming apparatuses face challenges in maintaining stable image density due to dispersion in developing agent and photo conductor properties, leading to issues like ghosting, transfer failure, and premature toner cartridge depletion, as existing correction methods are insufficient for low dot counts and high image densities.
Innovation Solution
An image forming apparatus with an outputted image density control system that forms patch images, counts pixels, measures toner supply, and adjusts target density values based on the ratio of toner supply to pixel count, ensuring accurate density control and prolonged toner cartridge life by correcting toner consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional density correction methods are used with a single light beam sensor, then manufacturing cost and apparatus size are reduced, but image density stability deteriorates due to dispersion in developing agent and photo conductor properties
Solution Approach 1:
The patent divides the image formation process into two separate correction stages: toner density correction (using a first light beam sensor) and image density correction (using a second light beam sensor). This segmentation allows each sensor to focus on specific parameters, improving overall measurement accuracy and image density stability while maintaining cost-effectiveness through the use of simple optical sensors rather than complex measurement systems.
Solution Approach 2:
The patent introduces intermediate transfer bodies and correction patches as mediators in the measurement process. The correction patches are formed on the photo conductor, transferred to intermediate transfer bodies, and then measured by light beam sensors. This intermediary approach allows indirect measurement of density parameters, compensating for variations in developing agent and photo conductor properties while keeping the apparatus structure relatively simple.
2Reliability
If toner density is increased to maintain image quality at high image ratios, then image density stability improves, but toner consumption increases leading to premature cartridge depletion
Solution Approach 1:
The patent implements feedback control by measuring the density of correction patches with light beam sensors and using these measurements to adjust development bias voltage and toner supply. The system continuously monitors image density and toner density, comparing measured values against target values, and automatically corrects deviations. This feedback mechanism ensures optimal image quality is maintained while preventing excessive toner consumption that would lead to premature cartridge depletion.
Solution Approach 2:
The patent dynamically adjusts key parameters including development bias voltage, toner supply rate, and exposure conditions based on measured density values and environmental conditions such as temperature and humidity. By changing these parameters in response to actual measurement data, the system maintains stable image quality across varying operating conditions while optimizing toner usage efficiency and preventing premature cartridge depletion.
3Reliability
If development bias is raised to suppress quality drop in density, then image density uniformity improves, but toner discharge amount increases accelerating toner consumption
Solution Approach 1:
The patent uses feedback control to adjust development bias voltage based on measured image density and toner density from correction patches. Rather than continuously raising the bias voltage, the system makes precise, measured adjustments only when and where needed to achieve target density values. This feedback-based approach maintains image density uniformity while avoiding excessive toner discharge that would accelerate consumption and deplete the cartridge prematurely.
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
The system stabilizes image density over time, preventing ghosting and transfer failures while optimizing toner usage, ensuring consistent image quality and extending toner cartridge life by dynamically adjusting target density values.
Implementation Method 1
a charging portion, light beam scanning portion, developing portion, transferring portion and the like, disposed around a photo conductor drum as an image carrying body such that they oppose the peripheral surface of this photo conductor drum. The surface of the photo conductor drum is charged uniformly by applying a predetermined voltage to the charging portion
Implementation Method 2
a static latent image is formed with a light beam from the light beam scanning portion
Implementation Method 3
that image is developed by supplying toner in the developing portion
Implementation Method 4
the toner image is transferred to an intermediate transfer body or the like by the transfer portion
Implementation Method 5
The paper to which the image is transferred is subjected to fixing processing by the fixing portion during the transportation up to a discharge port
Data Source
AI summary
An image forming apparatus including: an outputted image density control portion that forms a patch image and determines an outputted image density control condition based on a comparison result of the density of the patch image with a preliminarily set target value; a pixel count portion capable of counting the amount of image pixel at the time of image formation; a pixel count value accumulating memory portion that accumulates and stores the pixel count value; a toner supply portion; a toner supply amount measuring portion capable of measuring the amount of toner supplied to the developing device; a toner supply amount accumulating memory portion that accumulates and stores the toner supply amount; and a target value correcting portion that corrects the target value of the density of the patch image from the relation between a pixel count accumulating value and a toner supply amount accumulation value, is provided.