Detecting Screw Unevenness in Image Forming Apparatus
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electrophotographic image forming apparatuses struggle to detect screw unevenness, which causes periodic image density failure, especially when the image width is more than the screw pitch, as existing methods require costly image analysis mechanisms.
Innovation Solution
An image forming apparatus and method that uses a developing current detector to analyze changes in developing current during imaging of a stripe image with a width narrower than the screw blade period and a length longer than the screw unevenness period, allowing for detection of image density failure without an image analysis mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an image analysis mechanism is installed to detect screw unevenness, then detection capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the optical/image analysis mechanism with an electrical measurement system. Specifically, it uses a current detection mechanism that measures current values during the rotation of the developer feeder screw. This electrical measurement approach substitutes the complex optical imaging and analysis system, achieving screw unevenness detection through current variations caused by rotational resistance changes, thereby reducing device complexity while maintaining detection capability.
2Area of stationary object
If a full-width image is used for detection, then detection coverage is improved, but screw unevenness cannot be detected when image width exceeds screw pitch
Solution Approach 1:
The patent divides the detection process into segments by using a narrow stripe image whose width is less than the screw pitch. This segmentation allows the detection system to focus on a specific region where screw unevenness effects are visible in the current variations. By analyzing current changes during the rotation cycle within this narrowed detection zone, the system can accurately detect screw unevenness without the masking effect that occurs when the image width exceeds the screw pitch, thus resolving the contradiction between coverage and precision.
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
Enables the detection and potential repair of screw unevenness, improving image quality by analyzing developing current changes over time, even without an image analysis mechanism, thereby addressing the challenge of periodic image density failure.
Implementation Method 1
a developing current detector that detects a value of developing current that flows between the image carrier and the developer carrier during imaging
Data Source
AI summary
An image forming apparatus includes: a developer carrier; a screw-shaped developer feeder that feeds developer to the developer carrier; an image carrier on which an image is imaged with toner of the developer; a developing current detector that detects developing current between the image carrier and the developer carrier during imaging; and a controller that detects image density failure that is periodic and oblique to a rotation direction of the image carrier. The controller causes a stripe image to be imaged on the image carrier and analyzes change of the developing current with time during imaging of the stripe image, thereby detecting the image density failure. The stripe image has a width in a length direction of the image carrier narrower than a period of a blade of the developer feeder and has a length in the rotation direction longer than a period of the image density failure.