Image Forming Device Light Quantity Correction for Density Uniformity
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Solution Overview
Problem
Existing electrophotographic image forming devices suffer from a reciprocity failure phenomenon, leading to uneven image density and worsening jaggies in text/CAD image modes, which affects the performance at specified resolutions.
Innovation Solution
An image forming device employing an electrophotographic method with a light quantity corrector that adjusts light quantity correction values for multiple light-emitting elements, and a controller that manages these corrections to prevent differences in light quantity settings during text/CAD image modes, thereby maintaining uniform jaggies and resolution performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If light quantity correction is applied to resolve density level difference in half-tone images, then density uniformity is improved, but jaggies worsen in text/CAD image modes
Solution Approach 1:
The patent applies dynamic control by switching between different light quantity correction strategies based on image mode detection. For half-tone images, density correction is applied; for text/CAD images, uniform light quantity is maintained. This dynamic adaptation resolves the contradiction by preventing jaggy worsening in text/CAD modes while maintaining density uniformity in half-tone modes.
Solution Approach 2:
The patent changes the correction parameter strategy based on image type. In half-tone images, light quantity correction values are adjusted to resolve density level differences. In text/CAD images, the correction values are set to maintain uniform light quantity across all light-emitting elements, preventing jaggy deterioration. This parameter adaptation resolves the technical contradiction.
2Manufacturing precision
If multiple light exposures are performed at high scanning frequency to make density level difference unnoticeable, then density uniformity is improved, but device complexity and cost increase significantly
Solution Approach 1:
Instead of increasing scanning frequency or number of beams, the patent changes the light quantity correction parameters for each light-emitting element. By individually adjusting correction values based on detected density level differences, the system achieves density uniformity without increasing device complexity or the number of beams.
Solution Approach 2:
The patent replaces mechanical/optical solutions (multiple beams, high scanning frequency) with electronic control solutions (individual light quantity correction for each beam). This substitution achieves the same density uniformity goal while significantly reducing device complexity and cost.
3Manufacturing precision
If correction value is inverted and made smaller toward center light source to prevent density level difference, then density uniformity is improved, but jaggies worsen in text/CAD image modes
Solution Approach 1:
The patent dynamically adjusts the correction strategy based on image mode. For half-tone images, the inverted correction value pattern is applied to prevent density level differences. For text/CAD images, uniform correction values are applied to prevent jaggy worsening. This dynamic selection resolves the contradiction between density uniformity and jaggy quality.
Solution Approach 2:
The patent changes the correction value distribution pattern based on image type detection. In half-tone modes, correction values are inverted and decreased toward the center. In text/CAD modes, correction values are kept uniform. This parameter adaptation resolves the technical contradiction by preventing jaggy deterioration while maintaining density uniformity where needed.
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 solution effectively prevents worsening jaggies in text/CAD image modes and ensures sufficient performance at specified resolutions, while also preventing density level differences in half-tone images due to reciprocity failure.
Implementation Method 1
An electrophotographic image forming device is known in which a light beam emitted from a light source, such as a laser diode, is focused on a photoreceptor drum (image carrier) by a scanning optical system to form an electrostatic latent image on the surface of the photoreceptor drum
Implementation Method 2
a reciprocity failure phenomenon occurs in which, even when the total light quantity that is applied to the photoreceptor drum is the same, the formation state of the latent image differs when there is a difference in the relationship between the light quantity and the light exposure time
Data Source
AI summary
An image forming device employing an electrophotographic method that scans a surface of an image carrier with a multi-beam emitted from a plurality of light-emitting elements based on image data, including: a light quantity corrector that performs a light quantity correction so as to resolve a density level difference in an image, and sets a difference in a light quantity correction value of the plurality of light-emitting elements; and a controller that, when the image data is in a predetermined image mode such as text/CAD, controls the light quantity corrector so as to not set a difference in a set light quantity of the plurality of light-emitting elements.