Handheld Printer Nozzle Drying Prevention via Frequency-Based Ink Discharge Control
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Solution Overview
Problem
Handy mobile printers (HMPs) face issues with ink drying on nozzles, leading to degraded image quality due to the lack of a sheet conveyor, which results in incomplete ink discharge and the formation of 'dead pixels' when the user moves the printer over a medium.
Innovation Solution
The HMP incorporates a liquid droplet discharging controller that ensures each nozzle discharges ink for a controlled number of times greater than initially defined by the image data, with a frequency recorder tracking these discharges to prevent nozzle drying and maintain image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the HMP discharges ink only according to the image data without additional discharges, then the device complexity is reduced and operation is simpler, but ink drying on nozzles occurs leading to degraded image quality and dead pixels
Solution Approach 1:
The controller performs preliminary determination of whether additional ink discharges are necessary before completing the normal discharging process. By proactively identifying nozzles that require additional discharges based on discharge frequency criteria, the system prevents ink drying issues before they occur, rather than reacting after dead pixels are formed
Solution Approach 2:
The system implements a feedback mechanism where the controller monitors the discharge frequency of each nozzle and uses this information to determine whether additional discharges are needed. The discharge frequency serves as feedback that triggers corrective action (additional discharges) when nozzles are at risk of drying out
2Reliability
If the HMP discharges ink for more times than defined by image data, then nozzle drying is prevented and image quality is maintained, but the productivity and printing efficiency is reduced
Solution Approach 1:
Instead of performing additional discharges for all nozzles uniformly, the system applies partial action by determining additional discharges only for specific nozzles that meet the discharge frequency criteria. This selective approach ensures sufficient ink discharge for at-risk nozzles while avoiding unnecessary discharges for other nozzles, thereby maintaining printing efficiency
Solution Approach 2:
The system changes the discharge parameter (number of discharges) dynamically based on the discharge frequency of each nozzle. By adjusting the discharge count as a variable parameter rather than a fixed value, the system optimizes the balance between preventing nozzle drying and maintaining printing speed
3Manufacturing precision
If the HMP uses a sheet conveyor like traditional printers, then automatic sheet positioning and ink discharge accuracy are improved, but the device size increases and portability is lost
Solution Approach 1:
The system compensates for the lack of automatic sheet conveyance by implementing self-service mechanisms including user guidance for manual sheet positioning and automatic compensation for discharge positions based on detected sheet positions. The HMP serves its own positioning needs through sensors and control algorithms rather than relying on a mechanical sheet conveyor
Data Source
AI summary
A liquid droplet discharging apparatus includes a plurality of nozzles to discharge a liquid droplet onto a medium and a liquid droplet discharging controller to receive image data. The liquid droplet discharging controller controls each of the nozzles to discharge the liquid droplet in an amount defined by the image data onto a target discharging position on the medium, which corresponds to a pixel position defined by the image data. The liquid droplet discharging controller controls at least one of the nozzles to discharge the liquid droplet for a controlled number of times smaller than a number of times N representing an integer not smaller than 2 in an amount greater than the amount defined by the image data onto the target discharging position on the medium. A frequency recorder records the controlled number of times of discharging for each of the at least one of the nozzles.