Reading Apparatus Roller Control for Stable Scanning Accuracy
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Solution Overview
Problem
Existing image reading apparatuses face issues with maintaining reading accuracy due to fluctuations in conveying speed and torque requirements for motors, especially when using stepping motors, which consume excessive power and cause vibrations or bending of recording media.
Innovation Solution
A reading apparatus using brushless motors with a hardware processor that controls the rotational speed and torque of rollers based on their operating state, ensuring that rollers farther downstream rotate faster, and switches between speed and torque controls to maintain consistent conveying speed and reduce fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If stepping motors are driven to produce maximum torque to prevent losing steps, then conveying reliability is improved, but power consumption increases and excessive force is applied to the recording medium
Solution Approach 1:
The patent applies dynamics by switching between two control modes (speed control and torque control) based on the operating state of the motor. The control device determines whether to prioritize speed or torque output depending on whether the motor is in an acceleration phase or steady-state phase, making the control characteristics dynamic rather than fixed. This resolves the contradiction by applying maximum torque only when necessary (during acceleration) and using speed control during steady-state operation, thereby reducing overall power consumption while maintaining conveying reliability.
Solution Approach 2:
The patent changes the control parameters (switching between speed control and torque control modes) based on the motor's operating state. By monitoring parameters such as motor speed, acceleration, and load conditions, the control device adjusts the control mode to optimize the balance between reliability and power consumption. This parameter change approach allows the system to adapt to different operational requirements and avoid excessive power consumption while ensuring reliable conveying.
2Ease of operation
If downstream rollers carry large load from upstream rollers to maintain speed difference, then conveying function is improved, but conveying speed fluctuates causing recording medium vibration and reducing reading accuracy
Solution Approach 1:
The patent implements feedback control by continuously monitoring the operating state of motors and the position of recording media, then adjusting control parameters accordingly. The control device uses feedback information to determine when to switch between speed control and torque control modes, and to adjust the speed difference between upstream and downstream rollers. This feedback mechanism prevents excessive load transfer that would cause speed fluctuations and media vibration, thereby maintaining reading accuracy while ensuring proper conveying function.
Solution Approach 2:
The patent applies preliminary anti-action by proactively adjusting the speed difference between rollers and controlling torque output before load fluctuations can cause problematic vibrations. The control device anticipates potential issues by monitoring motor operating states and preemptively adjusting control parameters to prevent excessive load transfer and speed fluctuations, rather than reacting after problems occur. This maintains both conveying function and reading accuracy.
3Measurement precision
If speed difference between upstream and downstream rollers is maintained to ensure reading accuracy, then reading accuracy is improved, but torque requirements vary significantly causing motor operating instability
Solution Approach 1:
The patent applies dynamics by making the control mode adjustable based on operating conditions. Rather than maintaining a fixed control mode, the system dynamically switches between speed control and torque control depending on whether the motor is accelerating or in steady-state operation. This dynamic approach stabilizes motor operation by applying appropriate control characteristics for each phase, while still maintaining the necessary speed difference between rollers for reading accuracy.
Solution Approach 2:
The patent changes control parameters (switching between speed control and torque control modes) based on motor operating state to stabilize motor performance. By monitoring parameters such as acceleration, speed, and load conditions, the control device adjusts the control mode to prevent instability while maintaining the speed difference required for accurate reading. This parameter adaptation resolves the contradiction between maintaining speed difference and ensuring motor stability.
Data Source
AI summary
A reading apparatus includes a reader, a conveyor, motors and a hardware processor. The reader reads a surface of a recording medium with an image formed. The conveyor includes rollers disposed along a conveyance path that passes through a reading area of the reader, and conveys the recording medium being laid across the rollers. The motors rotate the rollers. The hardware processor controls operations of the motors such that the rollers located farther downstream in a conveyance direction of the recording medium rotate faster. As to at least one motor of the motors, the hardware processor switches between and performs a first control to adjust a rotational speed and a second control to adjust a torque, depending on an operating state of the motor.