Inkjet Driver Circuit Dynamic Voltage Selection
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Solution Overview
Problem
Inkjet printers with piezoelectric elements experience substantial energy loss due to power dissipation during charging and discharging, especially with higher jet frequencies or more nozzles, leading to inefficiencies in ink drop ejection.
Innovation Solution
A control system with a current source and a switch connected to multiple power supplies is used to minimize voltage difference over the current source, reducing power dissipation by selectively switching to the power supply with the lowest voltage difference, thereby optimizing the actuation of the piezoelectric element for ink drop ejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a piezoelectric element is actuated by charging and discharging with a constant power supply voltage, then ink drop ejection is achieved, but substantial power dissipation occurs
Solution Approach 1:
The patent applies dynamics by making the power supply voltage adjustable rather than constant. The control circuit dynamically selects different voltage levels from multiple power supplies based on the instantaneous voltage across the piezoelectric element, optimizing the charging/discharging process to minimize power dissipation while maintaining ink drop ejection functionality.
Solution Approach 2:
The patent changes the voltage parameter during the actuation cycle. By switching between multiple power supplies with different voltage levels, the system optimizes the voltage difference across the current source, thereby reducing power dissipation (P = V²/R) while still achieving the necessary piezoelectric deformation for ink drop ejection.
2Productivity
If a higher jet frequency or larger number of nozzles is used, then printing productivity increases, but energy loss becomes even larger
Solution Approach 1:
The dynamic voltage selection enables the system to handle higher jet frequencies efficiently. By rapidly switching between different power supply voltages based on real-time conditions, the circuit can maintain optimal power dissipation levels even at higher operating frequencies, thus supporting increased printing productivity without proportional energy loss increases.
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 significantly reduces power dissipation during charging and discharging of the piezoelectric element, improving the efficiency of ink drop ejection and reducing energy loss, with potential efficiency gains up to 95%.
Implementation Method 1
a piezoelectric element operatively coupled to the ink duct... Control means control actuation of a piezoelectric element, so that it deforms and a volume change is achieved in the ink duct
Data Source
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AI summary
The invention relates to an inkjet printing apparatus, comprising a print head, the print head comprising an ink duct, a piezoelectric element operatively coupled to the ink duct, and a control means for controlling an ink drop ejection from the ink duct by actuation of the piezoelectric element, the control means comprising a current source, a number of power supplies, and a switch, connected between the current source and the number of power supplies, characterized in that the current source is configured to generate a current for actuating the piezoelectric element by charging and discharging, and the switch is configured to connect the current source and one of said number of power supplies, said one of said number of power supplies being selected such that a lowest voltage difference over the current source exists.