Image Forming Apparatus Gradation Control via Bit Data Adjustment
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Solution Overview
Problem
Existing image forming apparatuses face challenges in maintaining gradation characteristics of output images due to variations in scanning speed, leading to significant differences in gradation characteristics between input and output images, especially when magnification correction is performed without an fθ lens.
Innovation Solution
An image forming apparatus that includes a photosensitive member, an exposure unit, a determination unit to determine the number of bit data per pixel, a selection unit to choose conversion conditions based on the bit data, and a generation unit to generate a PWM signal for driving the exposure unit, ensuring different numbers of bit data are used depending on the image data and density values to minimize gradation errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If magnification correction is performed by adding or deleting bit data irrespective of density value, then magnification correction is achieved, but gradation characteristics deteriorate
Solution Approach 1:
The patent applies local quality by differentiating the magnification correction process based on pixel density characteristics. High-density pixels (binary values 0 or 255) are corrected by deleting bit data, while low-density pixels (binary values 1-254) are corrected by adding bit data. This localized approach ensures that gradation characteristics are preserved for low-density pixels while achieving magnification correction for high-density pixels, thereby resolving the contradiction between magnification correction accuracy and gradation quality.
2Manufacturing precision
If the number of bit data per pixel is varied to correct magnification, then magnification correction is improved, but gradation characteristics are reduced
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the number of bit data per pixel based on the pixel's density value and position. For high-density pixels, the number of bit data is reduced through deletion, while for low-density pixels, the number of bit data is increased through addition. This parameter adjustment is performed selectively according to pixel characteristics, enabling magnification correction while preserving gradation characteristics across different density regions.
3Device complexity
If bit data is added or deleted irrespective of position, then magnification correction is simplified, but image quality deteriorates
Solution Approach 1:
The patent implements local quality by making the bit data addition or deletion process position-dependent. The correction method is selected based on the pixel's position in the main scanning direction and its density value. This position-aware approach ensures that magnification correction is applied appropriately across different regions of the image, maintaining image quality while achieving the required magnification correction.
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 suppresses the reduction in gradation characteristics of output images by dynamically adjusting bit data based on scanning position and density values, improving image quality by maintaining consistent gradation across the image forming process.
Implementation Method 1
an image is formed by forming an electrostatic latent image on a photosensitive member through control of laser in accordance with an image signal
Data Source
AI summary
Provided is an image forming apparatus including: an exposure unit scanning a photosensitive member with a light beam radiated by a light source which is driven by a driving unit; a determination unit determining a number of bit data per pixel for a predetermined pixel of image data; a selection unit having conversion conditions for converting the image data into a bit pattern for the driving, and selecting a predetermined conversion condition depending on the determined number of bit data, the conversion conditions set such that numbers of bit data included in the obtained bit pattern for the radiating are different, and that the numbers of bit data are different depending on the image data; and a generation unit generating, based on the selected predetermined conversion condition and a density value of the predetermined pixel, the bit pattern for generating a PWM signal for the driving for the predetermined pixel.