Light Emitting Device Group Correction for Density Unevenness
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Solution Overview
Problem
In image forming apparatuses, density unevenness occurs due to variations in light intensity among light emitting elements, which is exacerbated by the need for increased width and speed, making it difficult to adjust light emission time for correction, especially when using self-scanning light-emitting-device array chips.
Innovation Solution
The light emitting device divides light emitting elements into groups, using a first correction method to uniformly adjust light intensity on a group-by-group basis by adjusting voltage, and a second method to individually adjust light emission time, allowing for high-speed scanning while ensuring adequate light emission time for each element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the light emitting device width or speed is increased to accommodate wide recording medium, then the light emission time assigned to each light emitting element becomes shorter, but adequate light emission time is needed to correct light intensity variations
Solution Approach 1:
The light emitting elements are divided into multiple groups along the main scanning direction, with each group independently controllable. This segmentation allows differential light emission time assignment to different groups, enabling correction of light intensity variations while maintaining high overall scanning speed.
Solution Approach 2:
The light emission time is made dynamic and adjustable for each group based on measured light intensity characteristics. The control unit dynamically assigns longer emission times to groups with lower light intensity and shorter times to groups with higher intensity, optimizing both uniformity and speed.
2Manufacturing precision
If light emission time is adjusted to correct density unevenness, then light intensity uniformity improves, but scanning speed decreases
Solution Approach 1:
By segmenting the light emitting elements into multiple independently controllable groups, the system can apply different emission time adjustments to different segments. This allows density uniformity correction without requiring uniform extension of emission time across all elements, thereby preserving scanning speed.
Solution Approach 2:
Each group is assigned a locally optimized light emission time based on its specific light intensity characteristics. Groups with lower light intensity receive longer emission times locally, while groups with higher intensity receive shorter times, achieving uniformity without globally reducing scanning speed.
3Manufacturing precision
If light intensity correction is performed on individual light emitting elements, then density unevenness is corrected, but device complexity increases
Solution Approach 1:
The system divides light emitting elements into groups and performs correction at the group level rather than requiring individual element control. This reduces control complexity while maintaining effective correction capability, as each group can be controlled as a unified unit with a common emission time parameter.
Solution Approach 2:
The invention applies correction to groups rather than every individual element, representing a partial action approach. This provides sufficient correction for density unevenness while avoiding the excessive complexity of individually controlling each light emitting element.
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 density unevenness in both main and subscanning directions, improving image quality by ensuring a wide light-intensity adjustable range and enabling high-speed operation without compromising image alignment.
Implementation Method 1
an optical recording unit that uses a light emitting device formed by arranging a large number of light emitting elements such as light emitting diodes (LEDs)
Implementation Method 2
an optical element that is used for forming an electrostatic latent image by focusing light outputs of the light emitting elements and exposing a photoconductor to light
Data Source
AI summary
A light emitting device includes a light-emitting element row that includes light emitting elements arranged in a row in a main scanning direction, an optical element that is used for forming an electrostatic latent image by focusing light outputs of the light emitting elements and exposing a photoconductor to light and a control unit that controls light emission of the light-emitting element row. The light-emitting element row is divided into groups, and the control unit uniformly corrects a light intensity of each of the light emitting elements included in the groups on a group-by-group basis by a first correction method so as to correct density unevenness in the main scanning direction.