Inkjet Head Gap Control for Sheet Lifting Prevention
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Solution Overview
Problem
Conventional line-type inkjet recording apparatuses face efficiency losses due to frequent interruptions in recording operations caused by thick recording sheets lifting from the conveyor belt, leading to soiling, damage, and jamming, which reduces their speed advantage over serial-type recording apparatuses.
Innovation Solution
An image recording apparatus with a recording head, conveyor, and controller that adjusts the distance between the conveyor and recording head based on the elevation of the recording medium, using a distance sensor to detect the medium's position and control the gap between the discharging surface and conveying surface to prevent contact, while also controlling the volume of ink droplets and conveying speed to minimize mist and maintain image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the recording sheet is conveyed continuously at high speed, then productivity is improved, but the recording sheet may lift from the conveyor belt causing soiling, damage, and jamming
Solution Approach 1:
The patent applies dynamics by making the gap between the conveyor belt and recording head adjustable rather than fixed. The gap is dynamically changed based on the recording sheet thickness detected by a sensor, allowing the system to adapt to different sheet conditions while maintaining continuous high-speed operation without sheet lifting or jamming
Solution Approach 2:
The patent changes the physical parameter of the gap distance between the conveyor belt and recording head based on detected sheet thickness. By varying this parameter according to actual sheet conditions, the system prevents sheet lifting while maintaining continuous conveyance at high speed, thus resolving the contradiction between productivity and reliability
2Reliability
If the gap between the conveyor and recording head is increased to prevent sheet lifting, then reliability is improved, but image quality deteriorates due to increased mist and reduced droplet precision
Solution Approach 1:
The system dynamically adjusts the gap size based on real-time detection of sheet thickness. When sheets are thick and prone to lifting, the gap is increased to prevent contact. When sheets are thin or normal, the gap is reduced to maintain image quality and minimize mist. This dynamic adjustment resolves the contradiction between reliability and manufacturing precision
Solution Approach 2:
The gap parameter is varied according to detected sheet thickness rather than maintaining a fixed large gap. This selective parameter change ensures prevention of sheet lifting only when necessary, while maintaining optimal gap size for image quality during normal operation, thus resolving the contradiction between reliability and manufacturing precision
3Reliability
If recording is stopped frequently to prevent sheet lifting, then sheet damage is reduced, but productivity decreases due to interrupted recording operations
Solution Approach 1:
The system performs preliminary detection of sheet thickness before the sheet reaches the recording head. Based on this advance detection, the gap is pre-adjusted to appropriate levels, preventing sheet lifting and potential damage before they occur. This allows continuous recording operation without interruption, resolving the contradiction between reliability and productivity
Solution Approach 2:
The system uses feedback from the thickness detection sensor to continuously monitor sheet conditions and dynamically adjust the gap. This closed-loop control prevents sheet lifting and damage while maintaining continuous operation, eliminating the need for frequent stops and thus resolving the contradiction between reliability and productivity
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 enhances operating efficiency by preventing unnecessary ink discharge, reducing waste and damage, and maintaining image quality by adjusting the gap and conveying speed in response to the recording medium's position, thus overcoming the limitations of conventional line-type recording apparatuses.
Implementation Method 1
a distance sensor that detects a distance of the recording medium from the conveying surface when the leading edge of the recording medium is placed at a first predetermined position on the conveying surface
Data Source
AI summary
An image recording apparatus improves the operating efficiency while preventing trouble due to the contact of a recording medium with a discharging surface of a recording head. A distance sensor for detecting the distance of the leading edge of a sheet from a conveying surface is provided upstream from the inkjet head in the conveying direction of the sheet. A gap control unit controls a frame moving mechanism to move the inkjet head up so that a gap between the discharging surface and the conveying surface increases when the distance detected by the distance sensor is above a first distance, and the gap distance may be increased by different amounts depending on the distance detected by the distance sensor. A discharging control unit controls the inkjet head to discharge ink droplets after the gap is increased.