Roll Sheet Width Detection Using Rotational Potentiometer
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Solution Overview
Problem
Conventional image forming apparatuses struggle to accurately detect and register the width of roll sheets due to the absence of necessary sheet restriction plates, leading to printing issues when roll sheets of different widths are used, as existing methods are designed for flat sheets and not roll sheets.
Innovation Solution
An image forming apparatus with a pair of placement stages, racks, a pinion, potentiometer, and rotatable members that allow for the detection of roll sheet width by varying resistance values, enabling accurate measurement and registration without the need for additional sheet restriction plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sheet restriction plates are arranged in the sheet conveyance path to detect roll sheet width, then width detection becomes possible, but the apparatus size increases and conveyance load increases due to contact between the sheet and restriction plates
Solution Approach 1:
The patent replaces the mechanical sheet restriction plates with a rotational detection system using a roller, encoders, and signal processing to detect roll sheet width. Instead of using physical plates that contact and restrict the sheet, the invention uses a roller that rotates in response to sheet width, with encoders converting this rotation into electrical signals for precise width measurement, thereby eliminating the need for complex mechanical restriction structures in the conveyance path.
Solution Approach 2:
The patent introduces a roller as an intermediary element between the roll sheet and the detection system. The roller rotates in response to the sheet width and transfers this mechanical motion to encoders, which convert it into electrical signals. This intermediary mechanism allows width detection without requiring direct contact between restriction plates and the sheet, reducing conveyance load and apparatus complexity.
2Stability of the object's composition
If sheet restriction plates are arranged on both sides of the roll sheet to guide the sheet, then sheet guidance is improved, but the means for rotating the roll sheet is interrupted and measurement accuracy decreases
Solution Approach 1:
The patent replaces the mechanical sheet restriction plates that physically guided the sheet with a rotational detection system. The roller rotates in response to sheet width and this rotation is converted into electrical signals by encoders, providing guidance and measurement functionality without physical plates that would interrupt roll rotation or cause contact issues during conveyance.
Solution Approach 2:
The roller in the invention serves multiple functions simultaneously: it guides the roll sheet, detects the sheet width through its rotation, and transfers this information to the detection system via encoders. This self-service mechanism eliminates the need for separate restriction plates and rotation means, allowing the roll to rotate freely while still achieving accurate width detection and guidance.
3Measurement precision
If restriction plates are used to detect separate sheet width by detecting voltage applied to variable resistor, then sheet width can be calculated, but this method cannot be applied to roll sheets as they do not collapse like separate sheets
Solution Approach 1:
The patent replaces the voltage detection method based on variable resistors (which relied on sheet collapse) with a rotational detection system. The roller rotates in response to roll sheet width, and encoders convert this rotation into electrical signals that can be processed to determine width. This mechanical-to-electrical conversion system is universally applicable to both separate sheets and roll sheets, eliminating the limitation of the voltage method.
Solution Approach 2:
The patent changes the detection parameter from voltage (based on sheet collapse) to rotation angle (based on roller rotation). The roller's rotation angle corresponds to the roll sheet width, and this angular parameter is converted into electrical signals by encoders. This parameter change makes the detection method adaptable to roll sheets, which do not collapse like separate sheets, while maintaining measurement precision.
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
Enables reliable detection and registration of roll sheet widths, preventing printing errors and maintaining a compact apparatus design by eliminating the need for redundant components in the conveyance path.
Implementation Method 1
a potentiometer which operates in association with rotation of the pinion; voltage detecting means for detecting a voltage value in accordance with a resistance value of the potentiometer
Data Source
AI summary
An image forming apparatus has rotatable members for rotatably retaining respective ones of flanges mounted to opposite ends of a roll sheet, and placement stages on which the roll sheet is to be placed and on which respective ones of the rotatable members are mounted. Racks are mounted to respective ones of the placement stages for undergoing movement to move the placement stages relative one another to vary a distance between the placement stages. A pinion is arranged between the racks for undergoing rotation to move the racks, and a potentiometer whose resistance value varies in accordance with a distance between the placement stages undergoing movement with rotation of the pinion is provided. An A/D converter outputs a value based on a resistance value of the potentiometer. A calculation device calculates a width of the roll sheet based on the value output from the A/D converter. A memory stores the calculated width of the roll sheet.