Print Head Positioning for Extended Thermal Image Length
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Solution Overview
Problem
Existing thermal printing methods are limited by the operational speed of the print head, which restricts the ability to generate images on continuously advancing substrates, and the length of images that can be printed is limited by the distance between the parked and upstream extreme positions of print head travel.
Innovation Solution
A method that utilizes a sensor device to predict substrate speed and control print head movement between upstream and downstream extreme positions, allowing the print head to move to the downstream extreme position in advance of printing, enabling the use of the entire distance for image printing and maintaining optimal relative speed between the print head and substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the print head is moved to the downstream extreme position in advance of printing, then the length of images that can be printed is increased, but the complexity of controlling print head movement is increased
Solution Approach 1:
The print head is moved to the downstream extreme position in advance of the printing operation, before the substrate reaches the optimal printing position. This preliminary positioning allows the full travel distance to be utilized for printing, enabling longer images to be printed without increasing control complexity, as the movement is predetermined based on the predicted substrate speed.
Solution Approach 2:
A sensor device detects the actual speed of the substrate and provides feedback to the controller. The controller uses this feedback to predict when the substrate speed will be less than a predetermined speed and automatically adjusts the print head position accordingly, maintaining optimal relative speed during printing while utilizing the full travel distance for longer images.
2Manufacturing precision
If the print head is moved in the direction of substrate advancement to increase relative speed, then image quality is maintained, but the distance available for printing is reduced
Solution Approach 1:
The print head is positioned at the downstream extreme position before printing begins, based on prediction of substrate speed. During printing, the print head moves from this downstream position towards the upstream position, utilizing the entire travel distance for printing while maintaining optimal relative speed through controlled movement direction and speed.
Solution Approach 2:
The print head movement is made dynamic and adaptable rather than static. The controller adjusts the print head movement in real-time based on the predicted and actual substrate speed, changing both the direction and speed of the print head to maintain optimal relative speed while maximizing the printing distance available.
3Device complexity
If the print head remains stationary at the printing station, then device complexity is reduced, but the ability to handle varying substrate speeds is limited
Solution Approach 1:
The print head is designed to be movable rather than stationary, allowing it to adapt to varying substrate speeds. The controller dynamically adjusts the print head position and movement based on sensor feedback about substrate speed, enabling the system to handle both fast and slow substrate speeds while maintaining image quality, without significantly increasing overall device complexity.
Solution Approach 2:
A sensor device continuously monitors substrate speed and provides feedback to the controller, which automatically adjusts print head movement accordingly. This feedback mechanism enables the system to adapt to varying substrate speeds dynamically, maintaining optimal printing conditions whether the substrate moves fast or slow, while keeping the control system relatively simple through automated response.
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 method allows for longer images to be printed by utilizing the full range of print head travel and ensures image quality by adjusting relative speed, even when substrate speed changes, preventing image quality issues due to slowing or stopping substrates.
Implementation Method 1
a sensor device to sense the speed of the substrate as the substrate moves relative to the base adjacent to the printing station
Implementation Method 2
printing elements of the thermal print head are selectively energised under computer control, to generate a desired image on the substrate
Data Source
AI summary
A method of printing utilizing a printing apparatus having a base, a printing station where a print head is mounted, the print head including a plurality of printing elements which are selectively energisable to generate an image on a substrate upon there being relative movement between the substrate and the print head, the print head being moveable relative to the base, and the apparatus including a sensor device to sense the speed of the substrate as the substrate moves relative to the base adjacent to the printing station, and a controller to receive input signals from the sensor device and to control print head movement relative to the base to achieve a desired relative speed between the print head and the substrate, and wherein the method includes predicting when the speed of the substrate relative to the base, as the substrate advances, will be less than a predetermined speed, and in response, moving the print head at the printing station to a downstream extreme position of print head travel, and during printing of an image, moving the print head from the downstream extreme position towards the upstream extreme position.