Inkjet Printhead Nozzle Discharge Detection via Temperature Derivatives
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Solution Overview
Problem
Conventional inkjet printing methods face challenges in accurately and quickly judging ink discharge failures in nozzles, leading to bulky and expensive apparatuses, and insufficient detection of nozzle failures.
Innovation Solution
A printing apparatus equipped with a printhead featuring a heater and temperature sensor, which monitors temperature changes and calculates second derivatives to determine normal discharge or failure, using a monitoring unit, extraction unit, arithmetic unit, addition unit, and judgment unit to accurately assess discharge states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reading apparatus is provided to detect printed patterns for judging nozzle discharge state, then detection capability is improved, but apparatus bulkiness and cost increase
Solution Approach 1:
The invention extracts the detection function from a separate reading apparatus and integrates it into the printhead itself through temperature sensors. This eliminates the need for external reading apparatus while maintaining detection capability, directly resolving the contradiction between detection accuracy and apparatus complexity.
Solution Approach 2:
The invention introduces temperature sensors as an intermediary element within the printhead to detect ink discharge states indirectly through temperature changes. This mediator approach enables accurate detection without requiring complex external reading apparatus, thus reducing overall system complexity while maintaining measurement precision.
2Measurement precision
If temperature detection elements are provided on heater board with wire bonding connections, then ink discharge source side detection is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The invention merges the temperature detection elements with the heater board structure itself, making them integral parts of the same component. This integration eliminates the need for separate wire bonding connections and multiple assembly steps, significantly simplifying manufacturing while maintaining the ability to detect ink discharge states at the source.
Solution Approach 2:
The heater board is designed to serve multiple functions: heating the ink for discharge and simultaneously detecting the discharge state through integrated temperature sensors. This multi-functionality eliminates the need for separate detection components and their associated complex wiring, reducing manufacturing complexity while achieving accurate detection.
3Reliability
If detection is performed based on printed check patterns, then discharge state judgment is possible, but detection timing is delayed and recovery operation is slow
Solution Approach 1:
The invention performs detection at the ink discharge source (in the printhead) before the ink is actually deposited on the medium. This preliminary detection of temperature changes occurs in real-time during the discharge process, enabling immediate identification of discharge failures and allowing for rapid recovery operations without waiting for pattern printing and subsequent reading.
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 accurate judgment of nozzle discharge states and failure occurrences at appropriate timing, preventing apparatus bulkiness and high costs while allowing for quick recovery and complementary printing operations.
Implementation Method 1
a printhead including a heater that generates heat energy to discharge ink
Implementation Method 2
a temperature sensor configured to detect a temperature; a monitoring unit configured to monitor a temporal change in the temperature detected by the temperature sensor
Data Source
AI summary
The present invention has been made to judge the discharge state of each nozzle accurately at an appropriate timing. For this purpose, a printing apparatus using a printhead including a heater and a temperature sensor to detect a temperature of the heater has the following arrangement. A temporal change in a detected temperature is monitored upon driving the printhead. In the temperature dropping process, temperatures are extracted at plural points of a time interval including a timing at which a feature point of the temporal change in the detected temperature in normal discharge appears. The second derivative of the temperature is calculated and added to obtain a total sum. The total sum is compared with a threshold defined based on the characteristic of the temporal change in the monitored temperature in discharge failure, thereby judging whether to normally discharge ink.