Density Detection Unit with Dual Spot Diameters for Image Control
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Solution Overview
Problem
Image forming apparatuses face challenges in maintaining high image density reproducibility due to variations in driving and image forming members, as well as fluctuations in temperature and environment, leading to inefficient developer consumption and calibration requirements.
Innovation Solution
An image forming apparatus with a detection unit comprising a light emitting element and two light receiving elements, where the spot diameter of specular reflected light is smaller than that of diffuse reflected light, allowing for precise control of image forming conditions by sampling the test pattern more frequently in the movement direction of the image carrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the test pattern size is reduced to decrease developer consumption, then developer consumption is reduced, but detection precision deteriorates because the test pattern becomes comparable to or smaller than the spot diameter of irradiated light
Solution Approach 1:
The detection is segmented into two independent measurements: specular reflected light detection and diffuse reflected light detection. Each measurement uses optimized light receiving elements with different spot diameters, allowing the test pattern to be smaller than the diffuse light spot diameter while still enabling accurate density control through the combination of both measurements
Solution Approach 2:
Diffuse reflected light measurement serves as an intermediary to compensate for surface condition variations. By measuring both specular and diffuse reflected light, the system can calculate the specular component more accurately even when the test pattern is small, thus maintaining detection precision while reducing developer consumption
2Length of stationary object
If the spot diameter of diffuse reflected light is reduced to enable smaller test patterns, then test pattern size can be reduced, but detection accuracy of diffuse reflected light deteriorates
Solution Approach 1:
The system changes the parameter of spot diameter differently for specular and diffuse reflected light measurements. The first light receiving element uses a smaller spot diameter optimized for specular reflection, while the second uses a larger spot diameter optimized for diffuse reflection, allowing accurate measurement of both components with a small test pattern
3Measurement precision
If high spatial resolution and high detection precision are achieved simultaneously, then detection accuracy is improved, but the effects of surface condition variations cannot be suppressed without averaging multiple measurements
Solution Approach 1:
The system uses feedback from diffuse reflected light measurement to correct specular reflected light detection. By measuring surface conditions through diffuse reflection and using this information to adjust the specular reflection measurement, the system achieves high detection accuracy while suppressing surface variation effects without requiring complex averaging procedures
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 reduces developer consumption while maintaining high precision in density control, effectively stabilizing image density and reproducibility by accurately detecting and controlling both specular and diffuse reflected light components.
Implementation Method 1
a light emitting element configured to irradiate light directed at the image carrier or the test pattern, and a first light receiving element and a second light receiving element configured to receive reflected light of the light irradiated by the light emitting element
Data Source
AI summary
An image forming apparatus includes an image forming unit, which forms a test pattern for density control on the image carrier; and first and second light receiving elements, which receive reflected light irradiated by a light emitting element. A spot diameter of a reflected light received by the first light receiving element is smaller than a spot diameter of a reflected light received by the second light receiving element, and a number of sampling of the test pattern in line with a movement direction of a surface of the image carrier by the first light receiving element is greater than that of the test pattern in line with the moving direction by the second light receiving element.