Nozzle Check Scanning Angle for Sensor Chip Gap Detection
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Solution Overview
Problem
Inkjet image forming apparatuses face misdetection of ink ejection malfunction nozzles due to gaps between sensor chips in contact image sensors, which can occur when thin lines in the test pattern pass through these gaps during scanning.
Innovation Solution
The apparatus includes a line sensor with plural sensor chips and a gap between them, and the sheet is slanted to ensure that thin lines pass through positions other than the gap, allowing the ejection malfunction determination unit to determine nozzle functionality based on densities at multiple positions in the scanned image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a contact image sensor with gaps between sensor chips is used for scanning test pattern images, then the scanning function is achieved, but misdetection of thin lines occurs when they pass through the gaps, leading to incorrect nozzle malfunction identification
Solution Approach 1:
The patent changes the scanning approach from perpendicular to the nozzle arrangement direction to an angled direction. By scanning at a specific angle, the thin lines that would normally pass through the gaps between sensor chips are redirected to pass through the active sensing areas, thereby avoiding misdetection while maintaining the use of contact image sensors with gaps between chips.
Solution Approach 2:
The patent modifies the scanning parameters by changing the angle at which the test pattern is scanned relative to the nozzle arrangement direction. This parameter change ensures that thin lines are captured by the sensor chips rather than passing through the gaps between them, thus improving both measurement precision and reliability of nozzle malfunction detection.
2Ease of operation
If the sheet is scanned in the transportation direction, then the scanning process is simple, but thin lines may pass through sensor chip gaps causing misdetection
Solution Approach 1:
Instead of scanning perpendicular to the nozzle arrangement (simple approach), the patent introduces an angled scanning direction. This dimensional change in the scanning approach ensures thin lines are captured by sensor chips while maintaining operational feasibility through controlled sheet feeding at the appropriate angle.
Solution Approach 2:
The patent introduces dynamic adjustment of the scanning angle relative to the nozzle arrangement direction. By making the scanning angle a variable parameter rather than a fixed perpendicular orientation, the system adapts to avoid gaps between sensor chips while capturing thin lines effectively.
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 approach effectively reduces misdetection of malfunctioning nozzles by ensuring clear detection of thin lines, even when they traverse the sensor chip gaps, thereby improving the accuracy of nozzle identification.
Implementation Method 1
the line sensor scans test pattern image on the sheet and generates a test pattern scanned image
Data Source
AI summary
A line sensor includes plural sensor chips and a gap between adjacent two sensor chips. In a test pattern image, a thin line is formed by ink ejected from a nozzle. Further, the line sensor scans the test pattern image on a sheet slanted from a transportation direction of the sheet and generates a test pattern scanned image. An ejection malfunction determination unit determines densities at at least two secondary-scanning-directional positions at a primary-scanning-directional position corresponding to each nozzle in the test pattern scanned image, and determines whether the nozzle is an ejection malfunction nozzle or not on the basis of the determined densities. Here, a slant angle of the sheet is set such that a primary-scanning-directional distance between two positions in the test pattern image corresponding to the two secondary-scanning-directional positions is larger than an arrangement interval of sensor pixels in the sensor chip.