Nozzle Plate Discharging for Electrostatic Inkjet Printers
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Solution Overview
Problem
The existing liquid ejecting apparatus using electrostatic attraction and electric field assist methods face issues with uneven or insufficient discharging of the nozzle plate, leading to abnormal charging states and interference with meniscus formation, resulting in inconsistent liquid ejection due to dirt accumulation and high humidity effects on surface resistance.
Innovation Solution
A liquid ejecting apparatus with a conductive discharging member that contacts the entire area of the nozzle plate, utilizing a porous material with interconnected cells impregnated with conductive liquid to thoroughly discharge the nozzle plate, ensuring even charging and preventing dirt spread, thereby maintaining optimal electrostatic forces for consistent ejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a high voltage is applied between the liquid in the nozzle and the counter electrode for liquid ejection, then the electrostatic attraction force is increased to enable high viscosity ink ejection, but the nozzle plate accumulates electric charge that prevents proper charging in subsequent ejection cycles
Solution Approach 1:
A conductive member is introduced as an intermediary between the nozzle plate and ground. This conductive member selectively discharges accumulated electric charge from the nozzle plate's ejecting surface while maintaining the electrostatic field necessary for liquid ejection. The conductive member acts as a mediator that removes harmful charge accumulation without disrupting the functional electric field between the charging electrode and counter electrode.
Solution Approach 2:
The invention periodically discards accumulated electric charge from the nozzle plate by conducting it through the conductive member to ground. This discarding of excess charge is performed between ejection cycles to recover the nozzle plate's charging capability, ensuring consistent electrostatic attraction force for subsequent liquid ejection operations.
2Reliability
If conventional discharging methods using ionic wind or contact brushes are used, then the nozzle plate can be discharged, but the liquid is dried up and hardened at the ejecting port or uneven discharging occurs
Solution Approach 1:
The conductive member serves as a gentle intermediary for charge discharge that does not involve direct mechanical contact or ionic wind. By providing a controlled conduction path, it avoids the harmful effects of liquid evaporation and hardening caused by ionic wind, and prevents uneven discharging associated with contact brushes.
3Productivity
If the nozzle plate is not discharged between ejection cycles, then the apparatus operates continuously, but the recorded charging from previous cycles causes excessive or insufficient liquid ejection
Solution Approach 1:
The conductive member is activated periodically between ejection cycles to discharge accumulated charge from the nozzle plate. This periodic discharging action resets the electrical state of the nozzle plate, ensuring that each subsequent ejection cycle starts with consistent charging conditions, thereby maintaining precise and uniform liquid ejection.
4Adaptability or versatility
If environmental humidity is high, then the surface resistance of the nozzle plate decreases and electric charge maintaining ability deteriorates, but the electrostatic force applied to liquid becomes unstable
Solution Approach 1:
The conductive member acts as a stabilizing intermediary that compensates for humidity-induced variations in nozzle plate surface resistance. By providing a controlled discharge path, it ensures that the electrostatic field remains stable and predictable regardless of environmental humidity conditions, maintaining consistent liquid ejection performance.
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
The solution enables secure and efficient discharging of the nozzle plate, preventing uneven charging and dirt accumulation, ensuring stable and consistent liquid ejection by maintaining appropriate electrostatic forces and preventing meniscus interference.
Implementation Method 1
a discharging device to discharge the charged nozzle plate
Implementation Method 2
an electrostatic voltage applying device to apply an electrostatic voltage onto liquid in the nozzle
Implementation Method 3
an electrostatic attraction force created by an electric field formed between various substrates configuring an object to receive the droplet and the nozzle
Implementation Method 4
a technology using a pressure by distortion of a piezoelectric element
Data Source
AI summary
In a liquid ejecting apparatus using the electrostatic attraction method or electric field assist method, a liquid ejecting apparatus where discharging of a nozzle plate is securely performed and appropriate liquid ejecting is possible is provide. The liquid ejecting apparatus is provided with an electrode; a liquid ejecting head, having, a nozzle plate including a nozzle opposed to the counter electrode to eject liquid, a pressure generating device to rise a meniscus of liquid at a ejecting port of the nozzle, and a charging electrode opposed to the counter electrode via the nozzle plate, an electrostatic voltage applying device to apply electrostatic voltage onto the liquid in the nozzle; a discharging device to discharge the charged nozzle plate; and a control device to control the electrostatic voltage applying device and the discharging device; wherein the discharging device provides a conductive discharging member detachable to an whole area of the nozzle plate opposed to the counter electrode.