Multi-Chip Exposure Head Correction for Uniform Image Density
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Solution Overview
Problem
Existing image forming apparatuses using electrophotographic methods face density unevenness due to variations in light amounts not only between chips but also among light emitting elements within a chip, which conventional corrections fail to address adequately.
Innovation Solution
The apparatus employs a configuration with two light emitting chips positioned differently along the photosensitive member's rotation axis, each with multiple light emitting elements, and utilizes digital-analog converters and circuit units to adjust light emission based on correction data, ensuring precise light amount control across all elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If correction is applied only between chips, then chip-level light amount differences are corrected, but density unevenness remains due to variations among light emitting elements within each chip
Solution Approach 1:
The patent applies local quality by implementing individual correction values for each light emitting element within chips. Instead of uniform correction across all elements, the system assigns specific correction values to each element based on its actual light emission characteristics, thereby addressing local variations and achieving uniform image density across the entire exposure area.
Solution Approach 2:
The patent changes the correction parameter from chip-level to element-level precision. By determining and applying individual correction values for each light emitting element based on measured light amounts, the system transforms the correction approach to address fine-grained variations, thereby eliminating density unevenness that coarser correction methods cannot resolve.
2Area of stationary object
If multiple light emitting chips are used to increase exposure coverage, then exposure area is expanded, but light amount variations between and within chips cause density unevenness
Solution Approach 1:
The patent applies local quality by implementing individual correction values for each light emitting element within chips. Instead of uniform correction across all elements, the system assigns specific correction values to each element based on its actual light emission characteristics, thereby addressing local variations and achieving uniform image density across the entire exposure area.
Solution Approach 2:
The patent segments the correction process into chip-level and element-level components. By dividing the exposure head into multiple chips and further segmenting each chip into individual light emitting elements, the system can apply targeted correction to each segment, ensuring uniform density across the entire expanded exposure area while accounting for variations at each hierarchical level.
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 approach effectively corrects light amount variations within and between chips, reducing density unevenness in the formed images, enhancing image quality by maintaining consistent light emission across the exposure head.
Implementation Method 1
a first light emitting chip including a plurality of first light emitting elements that are placed at different positions in the direction along the rotation axis of the photosensitive member
Data Source
AI summary
An image forming apparatus includes a light emitting chip and at least one processor. The light emitting chip includes a plurality of light emitting elements, a DAC outputting a voltage corresponding to a setting value, and a circuit unit that supplies a current to the plurality of light emitting elements based on the voltage. At least one processor is configured to set the setting value such that one light emitting element included among the plurality of light emitting elements emits light of a predetermined amount, and correct image data pieces that respectively correspond to the plurality of light emitting elements based on first correction data for correcting amounts of light respectively emitted by the plurality of light emitting elements. The circuit unit supplies a current to each of the plurality of light emitting elements based on the corrected image data pieces.