LED Exposure Correction for Density Uniformity
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Solution Overview
Problem
Image forming apparatuses face issues with density unevenness due to variations in LED element shapes and characteristics, as well as misalignment and fluctuations in optical characteristics, leading to vertical streaks and bands that degrade image quality.
Innovation Solution
An image forming apparatus that includes an image reading device and an image forming device, with a processor that generates a predetermined pattern on a recording medium, calculates correction values for light emission based on density data, and determines correct placement of the medium to adjust light emission amounts, thereby correcting density unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a predetermined pattern is formed and read with a scanner to calculate correction values, then density unevenness can be corrected, but the process becomes complex and time-consuming
Solution Approach 1:
The system performs preliminary density detection and correction value calculation by forming a predetermined pattern and reading it with a scanner before actual image formation. This preliminary action allows the correction values to be pre-calculated and stored in memory, so that during normal operation, only the pre-computed correction values need to be applied, significantly simplifying the real-time process while maintaining high density uniformity.
2Manufacturing precision
If correction values are calculated based on density data from a predetermined pattern, then vertical streaks and bands can be reduced, but the measurement precision may be insufficient without proper placement verification
Solution Approach 1:
The system uses the image reading device to read the predetermined pattern formed on the recording medium, calculates density data from the read image, and uses this feedback to determine whether the recording medium was placed correctly. Based on this feedback, the system either recalculates correction values with proper placement or notifies the user of placement errors, ensuring high measurement precision for accurate density correction.
3Manufacturing precision
If the light emission amount of LED elements is adjusted to correct density unevenness, then image quality improves, but the device complexity increases due to additional correction mechanisms
Solution Approach 1:
The system corrects density unevenness by changing the parameter of light emission amount for each LED element. Correction values are calculated based on density data from reading a predetermined pattern, and these correction values adjust the drive current or emission duration of each LED element. This parameter change approach allows effective correction of vertical streaks and bands while maintaining a relatively simple device structure, as it only requires modifying the electrical parameters of existing LED elements rather than adding complex optical components.
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 alleviates density unevenness not addressed by initial correction values, ensuring uniform image quality by accounting for variations in LED elements and other components, and correctly determining medium placement for accurate readings.
Implementation Method 1
an exposure device to expose the charged surface of the photoconductor to form an electrostatic latent image on the photoconductor
Implementation Method 2
an exposure device including a light-emitting element... to expose the charged surface of the photoconductor
Implementation Method 3
a charger to charge a surface of the photoconductor
Data Source
AI summary
An image forming apparatus includes an image reading device; an image forming device including a photoconductor, a charger, an exposure device including a light-emitting element, a memory to store a first correction value for correction a light emission amount of the light-emitting element, and a driver to drive the light-emitting element, a developing device, a transfer device, and a fixing device. The image forming apparatus further includes a processor to calculate a second correction value for correcting the light emission amount, based on density data of image data of a predetermined pattern on a recording medium; calculate a third correction value for correcting the light emission amount, based on the first correction value and the second correction value; and determine, before calculating the third correction value, whether placement of the recording medium on the reading table is correct based on the density data.