Printer Tension Control via Lever Feedback Loop

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Solution Overview

Problem

Existing printer technologies face challenges in maintaining consistent tension of recording media during printing, leading to variations in conveyance speed and poor print quality, especially when dealing with high rotational inertia media like roll paper.

Innovation Solution

An inkjet printer with a media conveyance mechanism, a printhead, a lever that moves based on tension changes, and a control unit that adjusts the media supply operation to maintain the lever in a target position, using a rotary encoder to detect and control the lever's movement, thereby minimizing tension variations and ensuring constant conveyance speed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If switching control is used to maintain loop size within threshold values, then the recording medium tension can be buffered, but significant tension or slack is produced just before control changes, causing conveyance speed fluctuations

Engineering Contradiction:

Improvetension bufferingVSAvoidconveyance speed stability

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The patent transitions from static threshold-based switching control to dynamic continuous control. The loop detection means continuously detects loop size, and the control unit dynamically adjusts the drive roller speed in real-time based on the detected loop size, eliminating abrupt control changes and maintaining stable conveyance speed throughout the printing process.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements continuous feedback control where the loop detection means constantly monitors the loop size and feeds this information back to the control unit, which continuously adjusts the drive roller speed. This closed-loop feedback system maintains loop size within optimal ranges without producing the significant tension variations that occur with threshold-based switching control.

Inventive Principle:

Principle #23Feedback

2Stability of the object's composition

If the drive roller is stopped to form a loop and then driven to increase loop size when detected as smaller than threshold, then slack can be created in the recording medium, but this on/off control causes great lever swinging and tension variation

Engineering Contradiction:

Improveloop formationVSAvoidcontrol operation complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical on/off switching control system with an electronic continuous control system. Instead of mechanically stopping and starting the drive roller based on threshold crossings, the system uses electronic sensing to continuously detect loop size and electronically controls the motor speed to maintain optimal loop conditions, eliminating mechanical shocks and lever swinging.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If threshold-based control is used to detect slack and switch conveyance operation, then recording medium tension can be regulated, but conveyance speed fluctuates greatly due to lever swinging

Engineering Contradiction:

Improvetension regulationVSAvoidconveyance speed precision

Core Design Contradiction:

Manufacturing precisionVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by continuously maintaining the loop size within optimal ranges before printing begins. The continuous detection and control system proactively adjusts the drive roller speed to prevent tension variations from occurring, rather than reacting to threshold crossings during the printing process, thereby ensuring stable conveyance speed throughout.

Inventive Principle:

Principle #10Preliminary action

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

This solution effectively reduces tension variations and maintains precise conveyance of the recording medium, ensuring high print quality by continuously detecting and adjusting the lever's position to maintain optimal tension, reducing the likelihood of slippage and wear on conveyance rollers.

Implementation Method 1

a rotary encoder that detects the position or movement of the lever in a stepless or multi-step manner

Methodology Applied

Scientific EffectRotary encoder detection:

Data Source

PatentUS9545803B2Printer with mechanism for controlling recording medium tension

Publication Date: 2017.01.17 SEIKO EPSON CORP

AI summary

An inkjet printer has a mechanism to counter change in the tension of the recording medium to convey the recording medium with more precision. Such printer has a media conveyance mechanism that conveys a recording medium; an inkjet printhead that prints on the conveyed medium when the printhead is located at a position opposed to the media conveyance mechanism; a media supply mechanism that supplies the medium to the media conveyance mechanism; a lever that is positioned between the media conveyance and media supply mechanisms and that moves to compensate and thus counter internal tension changes in the recording medium resulting from operation of these mechanisms; a detector that detects the movement or position of the lever; and a control unit that controls the media supply operation based on output from the detector so that the lever is urged back to or maintained in a home position.