Medium Conveying Control Using Encoder Pulses for Line Spacing
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Solution Overview
Problem
DC motors used in medium conveying apparatuses, such as scanners, experience speed variations due to external factors like load changes, leading to inter-line spacing issues in scanned images.
Innovation Solution
Implementing a DC motor-driven conveyance roller system with an encoder that outputs a first pulse signal varying with motor speed, and an imaging device that acquires images in response to a second pulse signal with a constant cycle, using a processor to adjust image acquisition based on detected pulse counts to maintain image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a DC motor is used to drive the conveyance roller, then the cost is reduced and speed adjustment is simplified, but the rotation speed varies due to external factors such as load variation, causing inter-line spacing issues in the scanned image
Solution Approach 1:
The system uses an encoder to detect the actual rotation speed of the DC motor and feeds this information back to the control unit. The control unit compares the detected speed with the target speed and adjusts the motor driving signal accordingly to maintain constant rotation speed, thereby ensuring consistent line spacing in the scanned image.
Solution Approach 2:
The system dynamically changes the driving parameters of the DC motor based on real-time speed detection. When the encoder detects speed deviation, the control unit modifies the motor's driving voltage or current to compensate for load variations, maintaining the rotation speed within a predetermined range and preventing image distortion.
2Manufacturing precision
If the rotation speed of the DC motor is maintained at a constant value, then the line spacing in the scanned image remains consistent, but the system complexity increases due to the need for speed control mechanisms
Solution Approach 1:
The system employs an encoder to continuously monitor the motor's rotation speed and provides feedback to the control unit. This feedback mechanism enables automatic speed regulation without requiring complex mechanical control structures, maintaining constant line spacing through electronic control.
Solution Approach 2:
The patent replaces complex mechanical speed control mechanisms with an electronic control system using an encoder and control unit. The encoder converts mechanical rotation into electrical signals for speed detection, and the control unit processes these signals to adjust motor speed electronically, simplifying the overall system architecture while maintaining precision.
3Manufacturing precision
If the control unit discards images acquired during speed variation, then the image quality is maintained, but the scanning productivity decreases due to image discarding
Solution Approach 1:
The control unit proactively adjusts the motor driving signal before significant speed deviation occurs by continuously monitoring encoder feedback. This preliminary correction prevents speed variations that would cause image quality degradation, eliminating the need to discard images and maintaining both image quality and scanning productivity.
Solution Approach 2:
The real-time feedback from the encoder enables the control unit to detect and correct speed deviations during the scanning process. By maintaining speed within the predetermined range through continuous adjustment, the system produces high-quality images without requiring image discarding, thus preserving scanning productivity.
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 solution stabilizes image quality by discarding or selecting images based on pulse count adjustments, mitigating the effects of motor speed fluctuations and ensuring consistent image resolution.
Implementation Method 1
an encoder to output a first pulse signal whose cycle varies according to a rotation speed of the DC motor
Data Source
AI summary
A medium conveying apparatus includes a conveyance roller to convey a medium, a DC motor to drive the conveyance roller, a processor to rotate the DC motor, an encoder to output a first pulse signal whose cycle varies according to a rotation speed of the DC motor, and an imaging device to acquire an image acquired by imaging a conveyed medium in response to a pulse of a second pulse signal whose cycle is constant. The processor detects a number of pulses of the second pulse signal included in a predetermined cycle of the first pulse signal, and discards images acquired by the imaging device in the same number of pulses as difference between the detected number of pulses and a reference number, in a next cycle of the predetermined cycle of the first pulse signal, when the detected number of pulses exceeds the reference number.