Nozzle Taper Geometry in Liquid Ejecting Heads for High-Speed Recording
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Solution Overview
Problem
Increasing the drive frequency of piezoelectric elements to achieve high-speed recording results in higher drive voltages, leading to increased heat generation and fluctuating viscosity, which affects droplet size and image density, causing uneven images.
Innovation Solution
A liquid ejecting head with nozzles having a diameter D and taper angle θ that satisfy the relationships θ≥2.1×D−36.4, D>22 μm, and θ<45°, along with a natural frequency Fr of 120 kHz, to stabilize droplet ejection and reduce drive voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the drive frequency is increased to achieve high-speed recording, then the recording speed is improved, but the drive voltage must be increased leading to heat generation and viscosity fluctuation
Solution Approach 1:
The patent changes the geometric parameters of the nozzle (diameter D and taper angle θ) to satisfy a specific relationship θ≥2.1×D−36.4. This parameter optimization allows the flow channel to operate efficiently at high drive frequencies while maintaining stable droplet ejection and reducing the required drive voltage, thereby resolving the contradiction between recording speed and energy consumption.
2Reliability
If the drive voltage is increased to eject droplets at high drive frequency, then the droplet ejection is maintained, but heat generation increases causing viscosity decrease and droplet size fluctuation
Solution Approach 1:
By optimizing the nozzle parameters (diameter D and taper angle θ) to satisfy θ≥2.1×D−36.4, the patent reduces the drive voltage required for droplet ejection at high frequencies. This parameter optimization minimizes Joule heating in the piezoelectric element, maintaining stable liquid viscosity and consistent droplet size, thus resolving the contradiction between ejection reliability and temperature control.
3Productivity
If the natural frequency is increased to enable high-speed recording, then the drive frequency can be increased, but higher drive voltage is required
Solution Approach 1:
The patent optimizes the nozzle geometric parameters (diameter D and taper angle θ) to satisfy θ≥2.1×D−36.4, which improves the flow channel characteristics and reduces the power required to drive the piezoelectric element at high frequencies. This allows high natural frequency operation for high-speed recording while minimizing the increase in drive voltage, resolving the contradiction between productivity and power consumption.
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
Stable droplet ejection is achieved at high drive frequencies with reduced drive voltage, maintaining consistent image density and preventing nozzle meniscus breakage, while allowing for high recording resolution and cost-effective manufacturing.
Implementation Method 1
The piezoelectric element applies pressure to the liquid in the pressure chamber to eject droplets from the nozzle
Implementation Method 2
When a high drive voltage is applied to a piezoelectric element, the amount of heat generated increases based on the law of Joule heating
Data Source
AI summary
There is provided a liquid ejecting head including a flow channel member and a piezoelectric element. The flow channel member includes a flow channel including a nozzle and a pressure chamber connected to the nozzle. The piezoelectric element is fixed to the flow channel member that applies pressure to the liquid in the pressure chamber and causes droplets to be ejected from the nozzle. The natural frequency Fr of the flow channel is 120 kHz or higher. The diameter D [μm] of the nozzle and the taper angle θ [°] of the nozzle satisfy the relationships: θ≥2.1×D−36.4, D>22 μm, and θ<45°.