Image Density Measurement with Dual Light Intensity Control
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Solution Overview
Problem
Existing image forming apparatuses face challenges in accurately detecting image density across a wide range due to variations in irradiation light amounts, leading to errors in density determination, especially in high-density areas and low-density regions, which affects the quality of printed images.
Innovation Solution
The apparatus employs a dual light intensity setting for measuring images, using a lower intensity for low-density areas and a higher intensity for high-density areas, allowing for precise density determination by adjusting light emission based on specific measurement conditions to optimize reflected light measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a high irradiation light amount is used for measuring pattern images, then the reflected light amount increases which allows detection of low-density areas, but the output value of the light receiving element becomes saturated for low-density areas and the image bearing member, which disturbs correct detection of density
Solution Approach 1:
The patent applies dynamics by making the irradiation light amount adjustable rather than fixed. The light emission unit is controlled to emit light at different intensities (first light amount for low-density areas, second light amount for high-density areas) based on the measurement conditions and pattern image density requirements, allowing the system to adapt to different measurement scenarios and avoid saturation while ensuring sufficient reflected light for detection.
2Measurement precision
If a low irradiation light amount is used for measuring pattern images, then the reflected light amount decreases which avoids saturation, but the output variation of the light receiving element in response to density variation becomes small, which enlarges conversion error
Solution Approach 1:
The patent applies local quality by using different irradiation light amounts for different density regions of the pattern image. Low-density areas are measured with a higher first light amount to ensure sufficient reflected light signal, while high-density areas are measured with a lower second light amount to avoid saturation. This localized adaptation of light intensity to the specific measurement requirements of each density region optimizes the output variation of the light receiving element and minimizes conversion errors.
3Device complexity
If the same irradiation light amount is used for both low-density and high-density pattern image measurement, then the measurement process is simplified, but density determination accuracy deteriorates in either low-density areas or high-density areas
Solution Approach 1:
The patent resolves this contradiction by implementing dynamic control of the irradiation light amount based on the density characteristics of the pattern image being measured. The control unit determines whether to use the first light amount or second light amount according to the measurement conditions, enabling accurate density determination across the full density range while maintaining a relatively simple measurement process through automated light amount selection.
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 enhances measurement accuracy across a wide density range, reducing errors and improving the overall quality of printed images by ensuring correct detection of density variations.
Implementation Method 1
a light emission unit; a measurement unit that measures reflected light from a measurement image formed on the image bearing member
Data Source
AI summary
An image forming apparatus that enhances measurement accuracy of a pattern image and improves quality of a printed image. Light emitted from a light emission unit based on a first measurement condition is reflected from an image bearing member, and first information is generated based on a measurement result of the image bearing member. Second information is determined based on the first measurement condition, the first information, and a second measurement condition. Light is emitted based on the first measurement condition when a first measurement image is measured, and an image forming condition is generated based on a measurement result of the first measurement image and the first information. Light is emitted based on the second measurement condition when a second measurement image is measured, and the image forming condition is generated based on a measurement result of the second measurement image and the second information.