Piezo Inkjet Nozzles Prevent Clogging via Periodic Vibration
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Solution Overview
Problem
Inkjet printing systems face nozzle clogging and discharge defects due to ink evaporation and drying in unused nozzles, particularly in sheet feed printing machines, leading to inefficiencies and production losses, especially with fixed-type line heads where purging is not possible.
Innovation Solution
Implementing a method that includes a vibrating step for all nozzles during printing on an elongated medium, with a selector to adjust the vibration time, and alternating between discharging and vibrating steps, prioritizing discharging on image areas and vibrating on non-image areas, to prevent clogging and maintain nozzle functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a meniscus of a nozzle is maintained in a resting state to prevent discharge defects, then discharge defects are reduced, but ink evaporation and drying still occur leading to nozzle clogging
Solution Approach 1:
The patent applies periodic vibration action to the piezoelectric element at a frequency of 100 Hz or higher during the resting state. This periodic vibration prevents ink from settling and drying in the nozzle while consuming minimal energy, thereby preventing nozzle clogging without requiring continuous ink discharge.
Solution Approach 2:
The patent utilizes mechanical vibration of the piezoelectric element to maintain ink flow in the nozzle. By applying vibration at 100 Hz or higher, the ink remains agitated and prevents solid content precipitation, effectively preventing clogging while the nozzle is not in discharge mode.
2Reliability
If swinging action is performed in a region between sheets before page printing, then discharge defects are prevented, but a sufficient space is required between mediums and printing time is lost
Solution Approach 1:
The patent maintains continuous useful action by applying vibration to the piezoelectric element during the entire resting period between printing operations. This eliminates the need for separate swinging actions between sheets, as the continuous vibration continuously prevents ink drying and discharge defects without interrupting the printing process.
Solution Approach 2:
By using high-frequency periodic vibration during the resting state, the patent achieves the same protective effect as swinging action but without requiring physical movement between sheets, thereby eliminating space requirements and time losses associated with sheet handling.
3Device complexity
If a line head of a fixed type is used, then printing structure is simplified, but ink dries more easily causing discharge defects
Solution Approach 1:
The patent applies mechanical vibration to the piezoelectric element in the fixed-type line head at a frequency of 100 Hz or higher. This vibration prevents ink from settling and drying in the nozzles, maintaining discharge reliability while preserving the structural simplicity and cost-effectiveness of the fixed-type line head design.
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 approach effectively prevents nozzle clogging, allows immediate reuse of idle nozzles, reduces production time losses, and simplifies printing data preparation by eliminating the need for individual nozzle settings, enhancing overall production efficiency and preventing discharge defects.
Implementation Method 1
In an inkjet printing system of a piezo system, ink filled in an ink chamber is pushed out due to deformation of a piezoelectric element applied with a voltage so that ink is discharged from a nozzle.
Implementation Method 2
there is a possibility of causing such a discharge defect that ink cannot be discharged straightly due to clogging in the nozzle or a partial clogging therein
Data Source
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Figure 3(a)~3(b)
AI summary
A method for controlling an inkjet printing apparatus which can prevent nozzle discharge defects in all nozzles and is excellent in production efficiency is provided. The present invention lies in a method for controlling an inkjet printing apparatus performing printing to an elongated printing medium 11, the inkjet printing apparatus being provided with a printing head 10 having a plurality of nozzles composed of an opening portion 21 from which ink is discharged, an ink chamber 22 communicating with the opening portion 21 to accommodate ink, and a piezoelectric element 23 attached to the ink chamber 22 via a vibrating plate 24, and the method having a discharging step of performing continuous application to the piezoelectric element 23 of a nozzle to be used with a pulse number of two or more waves per one printing element to deform the piezoelectric element, thereby discharge ink in the ink chamber 22 from the opening portion 21, and a vibrating step of performing application to the piezoelectric elements 23 of all the nozzles with a pulse number of one wave per one printing element to deform the piezoelectric elements, thereby imparting only vibrations to the inks in the ink chambers 22 without discharging the inks , where the discharging step and the vibrating step are performed alternately.