Ink Jet Recording Head with Segmented Discharge Ports
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Solution Overview
Problem
Ink jet recording heads face challenges in achieving high-quality image printing without grainy images due to increased ink mist and discharge failures, especially when using small ink droplets, which lead to higher head temperatures and mechanical damage, ultimately reducing print speed and throughput.
Innovation Solution
The recording head is configured with multiple discharge port groups of different sizes to control ink discharge amounts, assigning brighter inks like yellow to middle-sized ports to minimize grainy effects and ink mist, thereby reducing the number of dots required and preventing discharge failures by managing head temperature and ink mist accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If small ink droplets are used to achieve high-quality image printing without grainy images, then image quality is improved, but ink mist increases and adheres to the discharge port causing discharge failure
Solution Approach 1:
The discharge port group is segmented into multiple discharge ports with different discharge amounts (first through fourth discharge ports). This segmentation allows the system to use a mix of small and large droplets rather than uniformly small droplets, reducing overall ink mist generation while maintaining image quality in critical areas.
Solution Approach 2:
Different discharge ports are assigned different discharge characteristics (small vs. large discharge amounts) based on local requirements. The fourth discharge port with intermediate discharge amount is specifically assigned to yellow ink to balance image quality and mist reduction, while other ports handle different colors or functions.
2Productivity
If the number of discharge ports is increased to achieve high-density recording, then recording speed and resolution are improved, but head temperature increases causing mechanical damage
Solution Approach 1:
The heating device is segmented into multiple independent heating elements (first through fourth heating devices) corresponding to different discharge ports. This allows selective activation of heating elements based on image requirements, reducing overall thermal load on the head while maintaining recording speed.
Solution Approach 2:
The system uses periodic pulse driving of heating devices to generate bubbles for ink ejection. By controlling the duty cycle and timing of pulse signals, the system achieves high-speed recording while allowing thermal dissipation between pulses, preventing excessive temperature buildup.
3Manufacturing precision
If small discharge ports are used to reduce dot size, then image quality is improved, but the number of dots required increases leading to higher head temperature
Solution Approach 1:
The discharge port group combines small discharge ports (first and second types) with a larger fourth discharge port type. This segmentation allows the system to use fewer total dots by leveraging the larger fourth discharge ports for areas where fine detail is less critical, reducing the cumulative thermal load from repeated heating cycles.
Solution Approach 2:
Different discharge port types are strategically assigned to different ink colors and image regions. The fourth discharge port with larger discharge amount is assigned to yellow ink, reducing the number of heating cycles required for yellow regions, while smaller ports handle colors requiring finer detail, optimizing the balance between image quality and thermal management.
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 allows for high-quality image printing without reducing print speed, reducing ink mist and discharge failures, and extending the number of pages printable by controlling head temperature and minimizing mechanical stress on the heating device.
Implementation Method 1
A heating device (i.e., an electrothermal conversion device) provided at the discharge port responds to a pulse drive of several to several tens of microseconds to form a bubble by film boiling
Data Source
AI summary
An ink jet recording head configured to perform recording by discharging at least two types of ink onto a recording medium while scanning the recording medium. The head includes a first discharge port group and a second discharge port group configured to discharge a first ink, and a third discharge port group and a fourth discharge port group configured to discharge a second ink different from the first ink. The fourth discharge port group discharges a smaller amount of ink at a time from a single discharge port than the third discharge port group, the second discharge port group discharges a smaller amount of ink at a time from a single discharge port than the first discharge port group. The fourth discharge port group discharges a smaller amount of ink at a time from a single discharge port than the first discharge port group, and discharges a larger amount of ink at a time from a single discharge port than the second discharge port group.