Printer Head Voltage Control for Ink Density Uniformity
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Solution Overview
Problem
Changing the jetting frequency of an ink jet printer's head based on the speed of the print object leads to density unevenness in the printed image due to varying jetting speeds.
Innovation Solution
A controller adjusts the output voltage of the power circuit based on the determined jetting frequency, using correction values to maintain a constant jetting speed of ink droplets from the nozzles, thereby minimizing density unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the jetting frequency of the head is changed based on the speed of the print object, then the productivity is improved, but the manufacturing precision deteriorates due to density unevenness in the printed image
Solution Approach 1:
The patent applies parameter changes by adjusting the output voltage of the power circuit based on the determined jetting frequency. The controller changes the voltage parameter to compensate for variations in jetting speed, thereby maintaining constant droplet velocity and uniform density in the printed image while allowing jetting frequency to vary for productivity improvement.
2Adaptability or versatility
If the jetting frequency of the head is changed based on the speed of the print object, then the adaptability is improved, but the manufacturing precision deteriorates due to varying jetting speed
Solution Approach 1:
The controller dynamically changes the output voltage parameter of the power circuit according to the determined jetting frequency. This parameter adjustment compensates for the effect of frequency changes on jetting speed, maintaining consistent droplet velocity and ensuring printing precision while adapting to different print object speeds.
Solution Approach 2:
The system employs feedback by determining jetting frequency based on encoder signals indicating print object speed, then using this information to adjust the power circuit output voltage. This closed-loop control ensures that jetting speed remains constant despite variations in jetting frequency, resolving the contradiction between adaptability and precision.
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 ensures a consistent jetting speed of ink droplets across varying frequencies, reducing the likelihood of density unevenness in the printed image.
Implementation Method 1
Each of the heads 11 includes a CMOS circuit 30 having a PMOS transistor 31, an NMOS transistor 32, a resistance 35, two piezoelectric bodies 11b and 11b'
Data Source
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AI summary
A printing apparatus (1) has a conveyance roller (5A) configured to convey a sheet (100) in a first direction, an encoder (6) provided at the conveyance roller (5A), a head (11) having a plurality of nozzles (11a) aligned in a second direction intersecting with the first direction and being configured to jet liquid to the sheet which is conveyed in the first direction by the conveyance roller and a controller (7) having a power circuit (21-26) configured to apply voltage to the head for jetting the liquid. The controller is configured to: determine a jetting frequency for the head based on a signal outputted from the encoder; and change an output voltage of the power circuit depending on the determined jetting frequency.