Ink Viscosity Measurement Using Laser Level Detection
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Solution Overview
Problem
In pad printing, the viscosity of ink changes over time due to evaporation of thinner, leading to inconsistent print quality and increased rejects, as existing measurement methods are either too complex or unsuitable for continuous monitoring during the printing process.
Innovation Solution
A method involving setting the ink in motion within its container and measuring the local level over time to determine viscosity, using a simple and non-contact optical measurement, such as a laser beam, allowing for regular and precise assessment of ink viscosity during the printing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional spatula or flow cup methods are used to measure ink viscosity, then the measurement is simple and cost-effective, but the measurement precision is insufficient for continuous monitoring during printing
Solution Approach 1:
The patent replaces mechanical contact-based viscosity measurement methods (spatula, flow cup) with an optical measurement system. A laser beam measures the position of a sinker in the ink, and this position data is converted to viscosity values. This substitution enables precise, continuous, non-contact viscosity monitoring during the printing process without the limitations of traditional mechanical methods.
2Measurement precision
If rotational viscometers are used outside the pad printing machine, then precise viscosity determination is achieved, but the device complexity and handling requirements increase significantly
Solution Approach 1:
The patent integrates the viscosity measurement system directly into the pad printing machine's ink container. The ink container serves dual functions: holding the ink for printing and housing the optical viscosity measurement system. The sinker, laser beam, and evaluation unit are incorporated into the existing ink container structure, eliminating the need for separate external viscometers and reducing handling complexity.
Solution Approach 2:
The patent merges the viscosity measurement system with the ink container. The sinker is positioned within the ink container, and the laser beam measurement system is integrated into the container structure. This combination allows viscosity measurements to be taken directly within the printing machine without requiring separate measuring devices, thereby reducing device complexity and streamlining operation.
3Stability of the object's composition
If thinner is added continuously to counteract evaporation, then ink viscosity consistency is maintained, but the complexity of the control system increases
Solution Approach 1:
The patent implements a feedback control system where the optical viscosity measurement continuously monitors ink viscosity during printing. The evaluation unit processes the measured viscosity data and automatically controls the thinner supply to maintain optimal viscosity levels. This closed-loop feedback mechanism maintains ink composition stability without requiring complex manual intervention or elaborate control systems.
Solution Approach 2:
The system enables the ink viscosity control to be self-regulating. The optical measurement system continuously monitors viscosity, and the evaluation unit automatically adjusts thinner addition based on real-time measurements. This self-service approach maintains consistent ink viscosity throughout the printing process without requiring external complex control mechanisms or frequent manual adjustments.
4Productivity
If optical measurement with laser beam is used, then non-contact continuous monitoring is enabled, but the measurement of local level in moving ink becomes challenging
Solution Approach 1:
The patent introduces a sinker that settles into the ink before measurement. The sinker is positioned in advance within the ink container, allowing it to reach equilibrium position in the ink. This preliminary positioning enables the optical laser measurement to accurately detect the ink level or sinker position even during printing operations, as the sinker provides a stable reference point amidst the moving ink.
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 reliable and continuous monitoring of ink viscosity, ensuring consistent print quality by automatically adjusting the thinner supply based on real-time measurements, reducing rejects and maintaining optimal ink viscosity.
Implementation Method 1
A non-contact optical measuring method, in particular the use of a laser beam, is used here
Data Source
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Figure 3a~3b
AI summary
A method and a device for measuring ink viscosity in pad printing are described. In this method, a printing ink (3) contained in an ink reservoir (2) is set in motion, and a measuring device (5) determines the time profile of the ink's movement (3) within the reservoir (2) by measuring the local level (hl, h2) of the ink within the reservoir (2). Based on this time profile, an evaluation unit then determines a measure of the ink's viscosity (3).