Liquid Ejection Head Electrode Voltage Control
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Solution Overview
Problem
In liquid ejection apparatuses, charged matter with opposite polarity from ink colloidal particles can attach to the surface of electrodes, potentially being burned by the heat generating resistive element, leading to reduced ejection speed and shortened head life.
Innovation Solution
A liquid ejection apparatus with a voltage application unit that adjusts electrode potentials, making the first electrode lower than the second before driving the resistive element and higher after start-up, to prevent attachment of charged matter to the electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a first electrode and second electrode are provided in the liquid chamber to control charged matter, then attachment of charged matter to electrodes is prevented, but device complexity increases due to additional electrodes and voltage control mechanisms
Solution Approach 1:
The electrode system is segmented into a first electrode (covering the heat generating resistive element) and a second electrode (positioned differently in the liquid chamber), each independently controlled by the voltage application unit. This segmentation allows differential voltage control to manage different aspects of charged matter behavior, resolving the contradiction by providing targeted control without requiring a completely complex unified system
Solution Approach 2:
The voltage application unit dynamically switches between two operational modes: applying voltage to make the first electrode lower potential than the second during standby, and reversing the polarity during driven state. This dynamic voltage switching enables the system to adapt to different operational requirements, preventing charged matter attachment while maintaining ejection functionality
2Speed
If voltage is applied between electrodes during standby state to prevent charged matter attachment, then ejection speed is maintained, but energy consumption increases
Solution Approach 1:
The voltage application operates periodically based on operational state: during standby state before heat generating resistive element driving, voltage is applied to prevent charged matter attachment and maintain ejection speed; during driven state, the voltage polarity is switched to facilitate the ejection process. This periodic action ensures ejection speed is maintained when needed while allowing energy-efficient operation during active ejection
Solution Approach 2:
The system changes the voltage parameter (potential difference between first and second electrodes) based on operational state. During standby, a specific voltage configuration is applied to prevent attachment; during driven state, the voltage parameter is switched to reverse polarity. This parameter change approach maintains ejection speed during standby while managing energy consumption through state-dependent control
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 configuration suppresses the attachment of charged ink components to the electrodes, maintaining stable ejection operations and extending the life of the liquid ejection head by preventing burns and ensuring consistent performance.
Implementation Method 1
a heat generating resistive element configured to generate energy for ejecting the liquid inside the liquid chamber
Implementation Method 2
a first electrode provided in the liquid chamber so as to cover the heat generating resistive element and being capable of forming an electric field in the liquid inside the liquid chamber, and a second electrode provided in the liquid chamber at a position different from a position of the first electrode and being capable of forming an electric field in the liquid inside the liquid chamber
Implementation Method 3
in a standby state before the heat generating resistive element is driven, the voltage application unit applies a voltage between the first electrode and the second electrode so as to make potential at the first electrode lower than potential at the second electrode
Data Source
AI summary
A liquid ejection apparatus, an ejection control method, and a liquid ejection head are capable of suppressing shortening of the life of the liquid ejection head and maintaining stable ejection operation. For this purpose, voltage is applied to upper electrodes and counter electrodes so as to make the voltage at the upper electrodes lower than the voltage at the counter electrodes before heat generating resistive elements are driven, and voltage is applied to the upper electrodes and the counter electrodes so as to make the voltage at the upper electrodes higher than the voltage at the counter electrodes at the same time as or after the start of driving of the heat generating resistive elements.