Toner Fogging Detection via Blank Sheet Measurement
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Solution Overview
Problem
Existing image forming apparatuses face challenges in accurately detecting toner fogging, especially when the developer's design life has expired, due to toner stains on the image carrier and transfer roller, which are not considered in previous detection methods, leading to inaccurate background density measurements and premature replacement.
Innovation Solution
The apparatus employs a conveyance unit, image forming unit, setting unit, and reading unit to differentiate between first and second transfer conditions, allowing for precise detection of toner fogging by reading the background density in a non-formation state and a non-image region, using image sensors to distinguish between regions with and without toner images, and determining fogging based on color differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If background density is measured by reading a sheet with no image formed on the front surface, then fogging detection is enabled, but toner stains on the image carrier and transfer roller cause measurement errors
Solution Approach 1:
The patent extracts the harmful toner stain factor from the measurement system by introducing a blank sheet that bypasses the image carrier and transfer roller. The blank sheet is fed directly to the reading unit, eliminating the source of contamination and enabling accurate background density measurement without toner stain interference.
Solution Approach 2:
The patent introduces a blank sheet as an intermediary medium between the reading unit and the image forming components. This blank sheet serves as a mediator that allows the reading unit to obtain accurate background density data without直接接触 (direct contact) with the toner-stained image carrier and transfer roller.
2Reliability
If developer is replaced before design life expiration to ensure print quality, then fogging is reduced, but resource waste occurs
Solution Approach 1:
The patent implements a feedback mechanism where the reading unit continuously monitors background density and the control unit compares it against threshold values. This feedback loop provides real-time information about developer condition, enabling replacement decisions based on actual performance degradation rather than predetermined time schedules, thus optimizing resource utilization while maintaining print quality.
Solution Approach 2:
The patent replaces the mechanical/time-based developer replacement system with an optical detection and control system. Instead of replacing developer based on fixed time intervals or usage counts, the system uses optical density measurement and automated control logic to determine the optimal replacement timing, substituting a sophisticated sensing and control mechanism for simple mechanical scheduling.
3Ease of operation
If existing fogging detection methods are used, then process adjustment can be executed, but accurate detection is impossible when toner stains are present
Solution Approach 1:
The patent segments the sheet handling process into two distinct paths: a normal image forming path and a blank sheet measurement path. The blank sheet measurement path is specifically designed to isolate the background density measurement from the image forming components, creating a separate measurement channel that is not contaminated by toner stains on the image carrier and transfer roller.
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 enhances the accuracy of toner fogging detection, preventing unnecessary developer replacement by accurately measuring background density and identifying the source of fogging, thus extending the developer's life and improving print quality.
Implementation Method 1
a reading unit generates a first reading result by reading the sheet that has passed through the image forming unit set in the first transfer condition, and generates a second reading result by reading the sheet that has passed through the image forming unit set in the second transfer condition
Data Source
AI summary
An image forming apparatus sets, on an image forming unit, one of a first transfer condition that does not cause an image to be formed on a sheet and a second transfer condition that causes an image to be formed on the sheet. The apparatus generates a first reading result by reading the sheet that has passed through the image forming unit set in the first transfer condition, and generates a second reading result by reading the sheet that has passed through the image forming unit set in the second transfer condition. The apparatus detects toner fogging based on the first reading result and a reading result out of the second reading result, the reading result concerning a non-image region in which no image is formed on a surface of the sheet.