Sheet Conveyance Torque Detection for Grammage-Based Image Formation
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Solution Overview
Problem
Conventional image forming apparatuses struggle to accurately set image forming conditions based on the grammage of recording materials, as they rely on thickness detection methods that are not precise enough, leading to inconsistencies in image quality.
Innovation Solution
An image forming apparatus that measures torque at a curved part of the conveyance path using a torque detection unit to determine grammage, adjusting image forming conditions such as transfer voltage, fixing temperature, and conveyance speed based on the detected grammage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If thickness detection method is used to determine recording material characteristics, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent replaces the mechanical thickness detection method with a torque-based detection system. A torque detection unit measures the torque required to rotate a roller that guides the recording material through a curved conveyance path. This substitution allows for more accurate grammage detection because torque measurement directly reflects the actual physical properties of the recording material (mass per unit area) rather than just its thickness, resolving the contradiction between simple device configuration and precise measurement.
2Measurement precision
If torque is measured at a curved part of the conveyance path, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent intentionally introduces a curved conveyance path with a specific radius of curvature (50mm to 150mm) to enable accurate torque-based grammage detection. The curved path creates a bending moment on the recording material as it passes through, and the torque required to maintain rotation of the guide roller directly correlates with the grammage. This curvature-based approach allows precise measurement while using a relatively simple structural modification to the conveyance system.
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 allows for more accurate setting of image forming conditions, improving image quality by ensuring proper fixation of toner images on various types of recording materials.
Implementation Method 1
a torque detection unit configured to detect a value related to a driving torque of the driving motor produced in a period in which the pickup roller feeds the sheet
Data Source
AI summary
An image forming apparatus includes a sheet feeding cassette, a pickup roller to feed a sheet stored in the sheet feeding cassette, a conveyance roller, an image forming portion, first and second conveyance guides, a driving motor, a torque detection unit, and a control unit. The torque detection unit detects a value related to a driving torque of the driving motor produced in a period when the pickup roller feeds the sheet. The control unit determines an image forming condition under which image formation is to be performed on the sheet at the image forming portion. The control unit determines the image forming condition in accordance with a performed result of detection by the torque detection unit performed in a period in which the sheet is guided with both the first conveyance guide and the second conveyance guide by being conveyed with the conveyance roller and the sheet is bent.