Image Forming Apparatus Density Correction via Sensor Feedback
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Solution Overview
Problem
Conventional image forming apparatuses face challenges in suppressing density variations in output images due to eccentricity or shape errors of photosensitive elements and developing rollers, which affect image quality.
Innovation Solution
The apparatus includes a photosensitive element, an optical scanning device, a developing unit, a photosensitive element period detecting sensor, and multiple density sensors that detect density variations. A processing device corrects the light source driving signal based on signals from these sensors to adjust image formation, thereby addressing density irregularities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to form images with laser light scanning, then image formation is achieved, but density variation occurs due to eccentricity or shape errors of the photosensitive element
Solution Approach 1:
The system performs preliminary detection of the photosensitive element's rotation period using a detection sensor, and pre-calculates correction values for light source intensity before actual image formation. This allows the control device to compensate for eccentricity and shape errors in advance, ensuring uniform image density without requiring mechanical perfection of the photosensitive element
Solution Approach 2:
The system continuously monitors the rotation period of the photosensitive element using a detection sensor and feeds this information back to the control device. The control device adjusts the light source driving signal based on this feedback to compensate for density variations caused by eccentricity or shape errors, maintaining consistent image quality
2Ease of operation
If the light source intensity is kept constant, then the scanning process is simple, but density variation occurs due to varying gap between photosensitive element and developing roller
Solution Approach 1:
The control device pre-calculates the appropriate light source intensity adjustments based on detected rotation period variations before the scanning process begins. This preliminary preparation allows the system to maintain simple operation while ensuring density uniformity through pre-planned compensation
Solution Approach 2:
The system dynamically adjusts the light source driving signal parameters based on the detected rotation period of the photosensitive element. By changing the light intensity parameter in response to rotation variations, the system compensates for density differences caused by varying gaps between the photosensitive element and developing 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 solution effectively reduces density variations in the sub scanning direction, leading to improved image quality by compensating for eccentricities and shape errors in both photosensitive elements and developing rollers.
Implementation Method 1
a photosensitive element being photosensitive and serving as a scanned surface
Implementation Method 2
a density sensor that detects a density variation of an image
Data Source
AI summary
An image forming apparatus that forms an image includes: a photosensitive element; an optical scanning device that includes a light source, and scans a surface of the photosensitive element in a main scanning direction with light emitted from the light source to form a latent image; a developing unit that develops the latent image; a photosensitive element period detecting sensor that detects a rotation period of the photosensitive element; a density sensor that detects a density variation of an image developed by the developing unit, in a sub scanning direction; and a processing device that corrects a driving signal of the light source according to the image information, based on an output signal of the density sensor and an output signal of the photosensitive element period detecting sensor.