Exposure Head Emission Timing Alignment for Image Quality
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Solution Overview
Problem
In electrophotographic image forming apparatuses, the arrangement of light-emitting points in exposure heads with multiple chips leads to irregularities in image formation due to positional disparities between adjacent light-emitting points, resulting in gaps greater than half the quantization unit, which affects the alignment and quality of the electrostatic latent image.
Innovation Solution
An image forming apparatus with an exposure device that includes a controller and memory to determine and adjust the emission timing of light-emitting points, using a tentative correction amount determination module and inter-chip adjustment module to ensure alignment of light-emitting points along a straight line, thereby reducing positional disparities and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple light-emitting chips are arranged in the main scanning direction with adjacent chips shifted in the sub scanning direction, then the light-emitting points can be continuously arranged without gaps, but positional disparities between adjacent light-emitting points occur, causing gaps greater than half the quantization unit in the electrostatic latent image
Solution Approach 1:
The patent applies preliminary action by pre-measuring the actual positions of all light-emitting points and pre-calculating the required emission timing corrections before actual image formation. The controller stores these correction values and applies them in advance, ensuring that even though chips are physically displaced, the emitted light points will be precisely aligned on the photoconductor surface.
Solution Approach 2:
The patent changes the emission timing parameter of each light-emitting point based on its measured positional deviation. By adjusting the emission time of each LED individually according to its actual position, the system compensates for physical misalignments between chips, ensuring that all light-emitting points converge to their intended positions on the photoconductor.
2Device complexity
If simple quantization of shift amounts is performed, then the correction process is simplified, but the gap between adjacent light-emitting points may become greater than half the quantization unit, resulting in image irregularities
Solution Approach 1:
The patent implements feedback by measuring the actual positions of light-emitting points, comparing them against the ideal grid positions, and using this feedback information to calculate precise emission timing corrections. The system continuously monitors and adjusts based on actual measurements, ensuring that correction values are optimized to minimize gaps between adjacent light-emitting points while maintaining computational efficiency.
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 reduces the gap between light-emitting points to not greater than half the quantization unit, enhancing the alignment and quality of the electrostatic latent image formed on the photoconductor, thereby improving the overall image forming process.
Implementation Method 1
a photoconductor is exposed to a light beam to form an electrostatic latent image on the photoconductor
Data Source
AI summary
In an image forming apparatus, a quantized amount of correction A is applied to emission timing with which each light-emitting point is to be caused to give off light emission to thereby align points of exposure to light emitted from the light-emitting points, substantially with a straight line extending in the main scanning direction on a photoconductor. The amount of correction A is adjusted by adding or subtracting one to or from one of the tentatively determined amounts of correction A1, A2 for light-emitting point (P1, P2) at opposite ends of two adjacent light-emitting chips, if formula (1) is not satisfied:ΔE-B<D2(1)where B is difference |C1−C2| between amounts of shift C1, C2 of the light-emitting points (P1, P2) stored in a memory, ΔE is a value derived from |A1−A2| multiplied by the quantization unit D, |A1−A2| is the difference between the amounts of correction A1, A2.