Inkjet Printer Gap Detection Using Intersecting Linear Patterns
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Solution Overview
Problem
Inkjet printers face issues with ink droplet misplacement on wave-shaped recording sheets due to varying gap levels between the ink discharging surface and the recording medium, leading to low-quality printed images.
Innovation Solution
A gap detecting device and method that print and read a gap level pattern on the recording medium, using intersecting linear patterns to detect fluctuations in the gap levels, allowing for precise adjustment of ink discharging timing to ensure accurate ink placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If inkjet printing is performed on a wave-shaped recording sheet with fixed ink discharging timing, then the printing process is simple and fast, but the ink droplets land in deviated positions resulting in low-quality printed images
Solution Approach 1:
The system performs preliminary detection of gap levels by printing a test pattern and reading it with a scanner before actual printing. Based on this preliminary information about the wave shape of the recording sheet, the control unit pre-calculates and stores corrected ink discharging timings for each position, enabling accurate printing without real-time complex calculations during actual printing
Solution Approach 2:
The system uses a scanner to read back the test pattern printed on the recording sheet and detects the actual gap levels. This feedback information about the wave shape is used to calculate corrected ink discharging timings, creating a closed-loop system that adapts to the specific recording sheet being printed
2Manufacturing precision
If ink discharging timing is adjusted for each position on the wave-shaped recording sheet, then ink landing position accuracy is improved, but the complexity of the printing system increases due to the need for gap detection and timing calculation
Solution Approach 1:
A test pattern consisting of linear patterns at specific angles serves as an intermediary to indirectly measure gap levels. Instead of using complex direct measurement devices, the system prints a simple geometric pattern and uses optical reading to detect gap variations, simplifying the measurement mechanism while maintaining precision
Solution Approach 2:
The system creates a digital copy or model of the gap level variations by reading the test pattern and storing the detected information in a table. This copied information about the wave shape is then used to determine corrected ink discharging timings, replacing the need for complex real-time calculations with simple table lookups
Data Source
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Figure 3A~3B
AI summary
An inkjet printer including an inkjet head with an ink discharging surface, a head scanning unit to drive the inkjet head to reciprocate along a first direction, and a pattern-printing control unit to control printing a gap level pattern on a recording medium, is provided. The pattern-printing control unit controls the inkjet head and the head scanning unit to print the gap level pattern including a plurality of unit patterns, in each of which the first linear pattern and the second linear pattern intersect each other, aligned along the first direction by manipulating the inkjet head to form a plurality of first linear patterns, which are formed to intersect the first direction, along the first direction, and to form a plurality of second linear patterns, which are formed to intersect the first linear patterns respectively at a same angle, along the first direction.