Sheet Size Detection via Resistance Segments
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Solution Overview
Problem
Conventional sheet size detecting mechanisms for automatic document feeders are costly due to their complex structure and require multiple components, making them expensive to fabricate and assemble.
Innovation Solution
A simplified sheet size detecting mechanism using a sheet guiding module, a sensing module with a contact element and circuit board featuring conductive segments and fixed resistors, and a control unit to determine paper size by measuring resistance values, reducing the need for additional tools and calibration procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional sensing module with photo interrupter, capacitive sensor and metallic elastic slice is used, then the sheet size detecting function is achieved, but the fabrication cost is high due to multiple components
Solution Approach 1:
The patent combines multiple sensing functions (contact detection and resistance measurement) into a single integrated sensing module. The conductive segments are directly formed on the circuit board, eliminating the need for separate photo interrupters, capacitive sensors, and metallic elastic slices. This merging reduces component count while maintaining detection accuracy.
Solution Approach 2:
The patent replaces complex mechanical sensing components with an electrical resistance-based detection system. Instead of using mechanical photo interrupters or capacitive sensors, the invention uses conductive segments with fixed resistors that provide different resistance values based on paper size, simplifying the sensing mechanism.
2Measurement precision
If a conventional sensing module with multiple components is used, then the sheet size detecting function is achieved, but the assembly process is complex and costly
Solution Approach 1:
The sensing module integrates the contact element, conductive segments, and fixed resistors into a single circuit board assembly. This eliminates multiple separate components that would require complex assembly procedures, making the manufacturing process simpler and more cost-effective.
Solution Approach 2:
The circuit board with conductive segments and fixed resistors serves as both the structural support and the sensing element. The resistance values are inherently provided by the fixed resistors connected to different conductive segments, eliminating the need for external calibration or additional adjustment mechanisms.
3Ease of manufacture
If conductive segments with fixed resistors are used instead of multiple sensing components, then the fabrication cost is reduced, but the measurement mechanism must be simplified
Solution Approach 1:
The patent uses different resistance values as the distinguishing parameter for detecting different paper sizes. Each conductive segment is associated with a fixed resistor having a specific resistance value, and the control unit determines paper size by measuring which resistance value is detected, maintaining precision through parameter differentiation.
Solution Approach 2:
The circuit board with conductive segments and fixed resistors serves multiple functions: it provides structural support, acts as the sensing element, and provides the measurement signal through resistance values. This multi-functionality eliminates the need for separate dedicated sensing 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 mechanism effectively detects paper size with reduced fabrication costs and simplified assembly, providing precise measurements without the need for complex calibration or additional tools.
Implementation Method 1
a first fixed resistor of the plural fixed resistors connected with the first conductive segment provides a first resistance value, and the circuit board issues a first sensing signal according to the first resistance value
Data Source
AI summary
A sheet size detecting mechanism includes a sheet guiding module, a sensing module and a control unit. The sensing module includes a contact element and a circuit board. The circuit board includes a first conducting part, a second conducting part and plural fixed resistors. The first conducting part includes plural conductive segments. The plural conductive segments are connected with the corresponding fixed resistors, respectively. While the sheet guiding module is moved relative to the sheet input tray, the contact element is moved with the sheet guiding module. When the electric connection between a first conductive segment and the second conducting part is established through the contact element, the corresponding fixed resistor provides a resistance value, and the circuit board issues a sensing signal according to the resistance value. The control unit acquires the size of the paper sheet according to the sensing signal.