Inkjet Recording Apparatus Gap Adjustment and Humidification
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Solution Overview
Problem
Existing inkjet recording systems face challenges in securely holding sheets with varying properties and efficiently humidifying recording heads, leading to potential image degradation and increased start-up times due to uneven humidity distribution and reduced holding force.
Innovation Solution
A recording apparatus with a conveying unit using rollers to nip the sheet between recording head units, a humidifying unit to supply humidified gas, and an adjusting mechanism to vary the gap between ink nozzles and the sheet, along with a control unit to optimize humidification and recording settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a humidified gas is supplied to the space between recording heads and the sheet to prevent ink nozzles from drying, then the recording heads are humidified, but the holding force of the sheet is remarkably reduced due to charge escape
Solution Approach 1:
The patent divides the sheet holding function into multiple locations: the sheet is held at both the front surface (by electrostatic attraction) and the rear surface (by vacuum attraction or electrostatic attraction). This segmentation ensures that even if humidity affects charges on one surface, the other surface maintains holding force.
Solution Approach 2:
The patent introduces a humidified gas supply mechanism that operates independently from the sheet holding mechanism. By controlling the timing and location of humidified gas supply, the system maintains sheet holding force while preventing nozzle drying. The humidified gas is supplied in a controlled manner that does not interfere with the electrostatic charges needed for sheet holding.
2Reliability
If vacuum attraction is used to hold the sheet, then the sheet can be held securely, but the introduced humidified gas is sucked by vacuum before the sheet is attracted, degrading humidification efficiency
Solution Approach 1:
The patent supplies the humidified gas to the recording heads before the sheet is fed into the recording position. This preliminary humidification ensures that the recording heads are properly moisturized before the sheet arrives, preventing the vacuum from sucking away the humidified gas. The timing is coordinated so that humidification occurs first, then the sheet is attracted and held.
3Reliability
If a pair of rollers nipping the sheet is used to hold and convey the sheet, then the sheet can be securely held, but the current of the introduced humidified gas is blocked by the roller, making it difficult to set desired humidity in a short time
Solution Approach 1:
The patent positions the humidified gas supply mechanism to target specific areas around the recording heads, rather than attempting to humidify the entire space uniformly. The gas is supplied locally where the recording heads are located, ensuring effective humidification without being blocked by the rollers. This localized approach achieves desired humidity levels quickly without compromising sheet holding 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
Ensures secure sheet holding and rapid humidification of recording heads, enabling high-quality image recording across various sheet types with reduced start-up times.
Implementation Method 1
a conveying unit configured to convey the sheet to a recording location, a pair of rollers nipping the sheet between a recording location of the first recording head unit and a recording location of the second recording head unit
Implementation Method 2
a humidifying unit configured to supply a humidified gas into a space where ink nozzles of the first and second recording head units are exposed
Implementation Method 3
an attraction belt or attraction roller which holds the sheet while attracting the rear surface of the sheet using a method of electrostatic attraction or vacuum attraction
Implementation Method 4
When the method of vacuum attraction is used to hold the sheet in the printer disclosed in Japanese Patent Laid-Open No. 2006-44021
Data Source
AI summary
Prior to recording, the gap between ink nozzles and a sheet is set to a first gap and a humidified gas is supplied in a short time. After that, the gap is varied from the first gap to a second gap smaller than the first gap and recording is then started.