Liquid Ejecting Head Adhesive Configuration Crosstalk
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Solution Overview
Problem
In liquid ejecting heads, particularly in ink jet type recording apparatuses, crosstalk occurs due to the displacement of partition walls caused by pressure changes, leading to variations in ink droplet ejection characteristics such as flying speed and amount, especially when using organic solvent-based inks which cause adhesive swelling and reduced bonding strength.
Innovation Solution
The solution involves optimizing the adhesive configuration by ensuring the adhesive's width-to-protrusion width ratio (0.05 ≤ L/W ≤ 0.3) and height-to-width ratio (3.8 < H/D ≤ 9.0) to enhance bonding strength, using an epoxy-based adhesive blended with silica to suppress adhesive swelling and outflow, and maintaining a swelling rate of 10% or less, thereby reducing crosstalk and maintaining ejection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a plurality of nozzles are disposed in high density to improve recording quality, then the pitch between nozzles is reduced, but the partition wall becomes very thin and is easily displaced by pressure change, causing crosstalk
Solution Approach 1:
The adhesive is applied in advance to the lower end of the partition wall before assembling the pressure chamber components. This preliminary application ensures that when the pressure generation unit operates and pressure changes occur during liquid ejection, the adhesive is already in position to immediately suppress partition wall displacement, preventing crosstalk between adjacent nozzles
Solution Approach 2:
The adhesive acts as an intermediary element between the partition wall and the pressure chamber structure. By positioning the adhesive at the lower end of the partition wall, it serves as a mediator that absorbs and distributes the pressure forces, preventing direct transmission of pressure that would cause partition wall displacement and crosstalk
2Reliability
If organic solvent-based ink is used to enhance weather resistance, then ink performance is improved, but the adhesive swells and bonding strength is reduced, causing partition wall displacement and crosstalk
Solution Approach 1:
The adhesive is designed with controlled dimensions (width L and protrusion width W with ratio 0.05 ≤ L/W ≤ 0.3) that allow it to serve its function of suppressing partition wall displacement effectively, while accepting that it may degrade over time due to organic solvent exposure. The adhesive performs its critical function during the operational life of the device, after which replacement of the entire head assembly is performed rather than attempting to preserve the adhesive
Solution Approach 2:
The dimensions of the adhesive are precisely controlled with specific parameter ratios (width-to-protrusion width ratio L/W between 0.05 and 0.3, and height-to-width ratio H/D between 3.8 and 9.0). These parameter changes optimize the adhesive's ability to suppress partition wall displacement while minimizing its exposure to organic solvent, thereby maintaining bonding strength throughout the operational period
3Strength
If adhesive is applied to join substrate and nozzle plate, then bonding strength is initially sufficient, but adhesive swells when exposed to organic solvent, reducing bonding strength and allowing partition wall displacement
Solution Approach 1:
The adhesive is positioned locally at the lower end of the partition wall rather than being applied uniformly across the entire joining surface. This localized application concentrates the adhesive where it is most needed to suppress partition wall displacement, while minimizing the total amount of adhesive exposed to organic solvent, thereby reducing overall swelling and maintaining bonding stability
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 effectively suppresses crosstalk and maintains consistent ink ejection characteristics by increasing the bonding strength between the partition wall and the nozzle plate, reducing pressure loss and ensuring reliable ejection performance even with organic solvent-based inks.
Implementation Method 1
operating a pressure generation unit such as a piezoelectric element or a heating element
Implementation Method 2
a substrate forming the pressure chamber and a member, for example, a nozzle plate, which is laminated on the substrate and defines a bottom portion of the pressure chamber, are joined by the adhesive
Implementation Method 3
adhesive is swollen by the ink that is used and then the bonding strength thereof may be reduced
Data Source
Figure 1
Figure 2A~2C
Figure 3~4
AI summary
A liquid ejecting head includes nozzles which eject the liquid; pressure chambers which communicate with the nozzle; a pressure chamber substrate in which the pressure chambers are defined by partition walls; a piezoelectric element which generates a pressure change in a ink inside the pressure chamber; and a nozzle forming substrate which is joined to the pressure chamber substrate by adhesive and defines the bottom portion of the pressure chamber, the organic solvent-based ink having a compression rate greater than a compression rate of water is ejected from the nozzle by driving the piezoelectric element and by generating the pressure change in the pressure chamber, and when a width of the pressure chamber in an arrangement direction of the pressure chambers is W and a width of the adhesive in the arrangement direction of the pressure chambers in a state where the adhesive is flowed out from between a lower end portion of the partition wall and the bottom member to the pressure chamber side and then is solidified is L, the following expression is satisfied, 0.05 ≤ L/W ≤ 0.3.