Printing Apparatus Encoder-Based Tension Control
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Solution Overview
Problem
The existing printing apparatuses face challenges in accurately controlling the conveyance of media due to differences in rotational speed between the feed driving unit and the roll, leading to reduced control accuracy.
Innovation Solution
The proposed solution involves a printing apparatus with a conveyance unit that includes a feeding unit, a conveyance roller pair, a feed driving unit, a first encoder to detect the rotational speed of the feed driving unit, and a second encoder to detect the rotational speed of the feeding unit. The control unit executes a feed adjustment operation by adjusting the tension of the medium based on the outputs from the encoders, with the second encoder's output used in the first period and the first encoder's output used in the second period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the roll is rotated at a rotational speed faster than the rotational speed of the feed driving unit, then the medium can be fed quickly to the conveyance roller pair, but a difference in rotational speed is caused between the feed driving unit and the roll, reducing control accuracy
Solution Approach 1:
The patent divides the rotational speed detection into two separate segments: one encoder detects the rotational speed of the feed driving unit, and another encoder detects the rotational speed of the feeding unit (roll). This segmentation allows the control unit to independently monitor both speeds and manage the speed difference, thereby maintaining control accuracy even when the roll rotates faster than the feed driving unit.
Solution Approach 2:
The patent implements a feedback mechanism where the control unit receives rotational speed information from encoders mounted on both the feed driving unit and the feeding unit. Based on this feedback, the control unit can adjust the driving speed to maintain synchronization and prevent medium conveyance errors, resolving the contradiction between high-speed feeding and control accuracy.
2Ease of operation
If control is performed based on the rotational speed of the feed driving unit, then the feed driving unit can be easily controlled, but the accuracy of the control is reduced due to the difference in rotational speed between the feed driving unit and the roll
Solution Approach 1:
The control system is segmented into two independent detection channels: one monitoring the feed driving unit and another monitoring the feeding unit. This allows the system to maintain simple control of the feed driving unit while simultaneously acquiring accurate speed data from the feeding unit encoder for precision control adjustments.
Solution Approach 2:
The control unit acts as an intermediary that receives data from both encoders and reconciles the speed difference. By using the feeding unit encoder output as a reference, the control unit mediates between the easy-to-control feed driving unit and the accuracy requirement, ensuring precise medium conveyance control.
Data Source
AI summary
A printing apparatus includes a conveyance unit, a printing unit, and a control unit. The conveyance unit includes a feeding unit, a conveyance roller pair, a feed driving unit, a first encoder, and a second encoder. The control unit is configured to execute a feed adjustment operation of adjusting tension of the medium fed from the feeding unit by controlling the feed driving unit such that the control unit executes the feed adjustment operation based on an output of the second encoder in a first period from a start of rotation of the conveyance roller pair until a specified time elapses and such that the control unit executes the feed adjustment operation based on an output of the first encoder in a second period after completion of the first period.