Inkjet Head Voltage Switching for Low-Heat Drive Waveforms
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Solution Overview
Problem
Existing liquid ejection heads generate drive waveforms inside the head, leading to heat generation and limitations in heat-sensitive applications due to wiring resistance and connector contact resistance, making them unsuitable for a wide range of environments and applications.
Innovation Solution
A liquid ejection head design that generates drive waveforms outside the head and uses a selection circuit to switch between internal fixed voltages and external drive waveforms, with capacitors to maintain waveform integrity, allowing for flexible waveform selection and use in various environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If drive waveforms are generated inside the liquid ejection head, then the response speed is improved and integration is enhanced, but heat generation increases due to wiring resistance and connector contact resistance
Solution Approach 1:
The patent segments the waveform generation function from the ejection execution function. The drive waveform generation circuit is separated into an external device, while the liquid ejection head retains only the switching function. This segmentation reduces the wiring resistance and connector contact resistance within the head, thereby reducing heat generation while maintaining fast response capability through the integrated switching circuit.
Solution Approach 2:
The patent extracts the waveform generation function from the liquid ejection head and places it in an external device. This extraction removes the heat-generating waveform generation process from the head, reducing internal heat generation. The head retains the essential switching function through integrated circuits, maintaining response speed while eliminating the heat problem.
2Temperature
If drive waveforms are generated outside the liquid ejection head, then heat generation is reduced, but waveform deterioration occurs due to wiring resistance and connector contact resistance
Solution Approach 1:
The patent implements dynamic switching capability within the head through integrated circuits that can select between multiple power supply lines (first power supply line with fixed voltage and second power supply line with variable voltage). This dynamic switching allows the system to adapt to different waveform requirements while maintaining signal integrity despite external waveform generation.
Solution Approach 2:
The integrated circuit in the head acts as an intermediary between the externally generated drive waveform and the piezoelectric actuator. It receives the external waveform signal and uses the selectable power supply lines to maintain waveform integrity, compensating for deteriorations introduced by external wiring and connectors.
3Device complexity
If multiple fixed voltages are applied and drive waveforms are generated inside the head, then device integration is improved and size is reduced, but application flexibility is limited
Solution Approach 1:
The patent implements multi-functionality by providing multiple power supply lines (first power supply line with fixed voltage and second power supply line with variable voltage) that can be selectively switched. This allows the same liquid ejection head to adapt to different drive waveform requirements and application scenarios, enhancing versatility while maintaining the integrated structure.
Solution Approach 2:
The patent introduces dynamic voltage selection capability through integrated circuits that can switch between different power supply lines based on the required drive waveform. This dynamic adaptability allows the head to accommodate various applications without sacrificing integration, resolving the contradiction between device complexity and adaptability.
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 the use of liquid ejection heads in a wide range of environments and applications by optimizing drive waveforms and reducing heat generation, ensuring consistent printing quality across different conditions.
Implementation Method 1
a plurality of piezoelectric elements, each of which is configured to vary the volume of a corresponding one of the pressure chambers in response to a drive signal
Implementation Method 2
a first capacitor connected to the first power supply line
Data Source
AI summary
A liquid ejection head includes nozzles, pressure chambers each storing liquid and communicating with a nozzle, a volume of each chamber being varied to eject the liquid from the nozzle, piezoelectric elements each configured to vary the volume in response to a drive signal, an integrated circuit configured to generate the signal, a first line through which a first voltage is supplied, its voltage level being held constant, a second line through which a second voltage is supplied, its voltage level varying, a first capacitor connected to the first line, and a first switch circuit configured to selectively connect the integrated circuit to either the first or second lines. The integrated circuit generates the signal using either the first or second voltage, and a capacitance of the first capacitor is no less than a total capacitance of the piezoelectric elements.