Low-Luminance LED Exposure Head Control for Highlight Contrast
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Solution Overview
Problem
Image forming apparatuses using light-emitting elements with low exposure luminance, such as LEDs and organic EL, face challenges in maintaining image reproducibility and contrast due to increased exposure time per pixel, leading to decreased linearity between exposure amount and photosensitive body potential, especially in highlight regions and thin lines.
Innovation Solution
An image forming apparatus that includes a processing unit to generate second image data by adjusting the emission of light-emitting elements based on a ratio of set exposure luminance and a reference value, specifically increasing or decreasing emissions in regions where contiguous bit data are present, to improve image reproducibility and contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If light-emitting elements with low exposure luminance (such as LEDs and organic EL) are used for an exposure head, then the apparatus can be reduced in size and complexity, but the exposure time per pixel must be increased, leading to decreased linearity between exposure amount and photosensitive body potential
Solution Approach 1:
The patent changes the exposure luminance parameter by selectively increasing or decreasing the luminance of individual light-emitting elements based on the image data. This allows compensation for the non-linear exposure characteristics of low-luminance LEDs, improving image reproducibility while maintaining the size benefits of using LED arrays instead of laser systems.
2Quantity of substance
If the exposure time per pixel is increased to compensate for low exposure luminance, then the same exposure amount can be achieved, but the linearity of the relationship between exposure amount and photosensitive body potential increases, decreasing contrast in highlight regions and thin lines
Solution Approach 1:
The patent applies local quality by adjusting the exposure luminance of individual light-emitting elements based on their specific position and the corresponding image region. Highlight regions and thin lines receive different luminance adjustments compared to other regions, preserving contrast while achieving the required exposure amount.
Solution Approach 2:
The system dynamically changes the exposure luminance parameter for different light-emitting elements based on the image content. By increasing luminance for elements corresponding to highlight regions and thin lines, the patent maintains linearity and contrast while achieving adequate exposure amounts.
3Volume of stationary object
If the exposure luminance is decreased to use light-emitting elements such as LEDs, then the apparatus size is reduced, but the reproducibility of images with low exposure amounts deteriorates
Solution Approach 1:
The patent compensates for the low exposure luminance of LEDs by dynamically adjusting the exposure luminance parameter for each light-emitting element. This allows the system to maintain image reproducibility for low exposure amount regions while using compact LED-based exposure heads instead of larger laser systems.
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
Enhances image reproducibility and contrast in highlight regions and thin lines by optimizing exposure luminance, ensuring that regions with higher densities approach their target values, thereby improving overall image quality.
Implementation Method 1
light-emitting elements with a relatively low exposure luminance (exposure intensity), such as LEDs and organic EL
Implementation Method 2
light-emitting elements with a relatively low exposure luminance (exposure intensity), such as LEDs and organic EL
Implementation Method 3
exposes the photosensitive body and form an image by developing the electrostatic latent image
Data Source
AI summary
An image forming apparatus includes: a setting unit configured to set an exposure luminance; and a processing unit configured to generate first image data, which is a set of bit data for controlling emission or non-emission of light-emitting elements of a exposure head, and second image data, which is obtained by increasing/decreasing light-emitting elements that emit light in the first image data. The processing unit is configured to generate the second image data by increasing/decreasing, in a first region, which excludes an edge region inside a region in which pieces of bit data indicating emission are contiguous in the first image data, bit data indicating emission, according to a ratio of a setting value of the exposure luminance and a reference value of the exposure luminance.