Embedded Densitometer for Thermal Printer Color Calibration
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Solution Overview
Problem
Thermal printers face challenges in onsite calibration due to variability in printer usage, media changes, and environmental conditions, which affect color accuracy and require manual intervention for calibration.
Innovation Solution
Integration of an embedded reflection densitometer within the printer that can sense donor patches and reflection density on the receiver medium, eliminating the need for a separate donor patch sensor assembly, and allowing for automatic calibration with minimal operator intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate donor patch sensor assembly is used to sense donor patches, then the positioning and edge detection of donor patches is improved, but the device complexity increases due to requiring multiple separate sensor assemblies
Solution Approach 1:
The patent combines the donor patch sensing function and the reflection density measurement function into a single embedded densitometer assembly. The densitometer can sense donor patches on the moving web and also measure reflection density on the printed receiver, eliminating the need for separate sensor assemblies and reducing overall device complexity while maintaining measurement precision
Solution Approach 2:
The embedded densitometer is designed with multi-functionality to perform both donor patch sensing and reflection density measurement. This universal sensor serves multiple purposes: positioning donor patches, detecting color patch edges, and measuring printed receiver density, thereby reducing the number of separate components needed
2Measurement precision
If manual calibration is performed with operator intervention, then the calibration accuracy can be adjusted, but the ease of operation decreases and calibration time increases
Solution Approach 1:
The system enables automatic calibration by embedding the densitometer within the printer, allowing it to autonomously measure reflection density and calculate new LUTs without requiring external operator intervention. The printer performs calibration measurements and adjustments automatically, improving ease of operation while maintaining calibration accuracy
Solution Approach 2:
The embedded densitometer provides continuous feedback on printed receiver density, enabling the system to automatically adjust LUTs and printing parameters. This feedback mechanism allows the printer to self-correct calibration issues and adapt to onsite variability without manual intervention
3Measurement precision
If factory calibration is performed with multiple LUTs, then the initial color accuracy is improved, but the adaptability to onsite variability decreases
Solution Approach 1:
The system transitions from static factory calibration to dynamic onsite calibration by embedding the densitometer. The printer can now perform real-time calibration measurements and adjust LUTs dynamically based on actual printing conditions, media variations, and environmental factors at the customer site, thereby improving adaptability while maintaining color accuracy
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
Enables precise color calibration and positioning of donor patches during printing, improving color rendition and reducing the need for manual calibration, thus enhancing the printer's ability to adapt to onsite variations.
Implementation Method 1
A light source provides light to at least one reflector that directs the light towards the densitometer
Data Source
AI summary
A sensor apparatus for providing two sensing operations within a thermal printer includes a densitometer with at least one light source that discriminates color and that is positioned in a first position for sensing donor patches within the thermal printer; the densitometer while in a second position provides signals from printed receiver media for internal color calibration of the thermal printer. At least one reflector directs light from the light source to the densitometer through a donor web when the densitometer is in the first position; and a switchable device repositions the densitometer from either the first position or the second position.