Printing Apparatus Nozzle Inspection via Perpendicular Line Sensor
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Solution Overview
Problem
Conventional image forming apparatuses face challenges in accurately inspecting nozzle discharge characteristics due to variations in scanning elements and light distribution characteristics, leading to inconsistent scanning results even when discharge characteristics are the same.
Innovation Solution
The apparatus employs an optical carriage with a line sensor where photodiodes are arrayed perpendicular to the nozzle array direction, allowing for precise scanning by moving the sensor in a direction crossing the conveyance path, thereby reducing variations in scanning characteristics and light distribution, and using a correction table to adjust for positional differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the scanning elements of the sensor are arrayed in the same direction as the nozzle array direction, then the sensor can scan the printed image, but the scanning result includes variation in scanning elements or variation in light distribution characteristics making accurate inspection impossible
Solution Approach 1:
The patent applies asymmetry by arraying the scanning elements (photodiodes) in a direction perpendicular to the nozzle array direction, rather than parallel to it. This asymmetric arrangement ensures that each nozzle's discharge characteristics are scanned by different photodiodes, eliminating the variation in scanning results caused by photodiode characteristics. The perpendicular arrangement creates a cross-directional scanning geometry that decouples the nozzle sequence from the sensor element sequence.
Solution Approach 2:
The patent transitions from a one-dimensional scanning approach (scanning in the same direction as nozzle array) to a two-dimensional scanning approach by arraying photodiodes perpendicular to the nozzle direction. This dimensional change allows the scanning system to capture image data across both the nozzle array direction and the perpendicular direction, enabling accurate inspection by eliminating the correlation between nozzle position and specific photodiode characteristics.
2Measurement precision
If a line sensor with photodiodes arrayed perpendicular to the nozzle array direction is used, then variation in scanning characteristics is reduced, but the device complexity increases
Solution Approach 1:
The patent applies asymmetry by arraying the scanning elements (photodiodes) in a direction perpendicular to the nozzle array direction, rather than parallel to it. This asymmetric arrangement ensures that each nozzle's discharge characteristics are scanned by different photodiodes, eliminating the variation in scanning results caused by photodiode characteristics. The perpendicular arrangement creates a cross-directional scanning geometry that decouples the nozzle sequence from the sensor element sequence.
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 enables consistent and accurate inspection of nozzle discharge characteristics by minimizing the influence of scanning element variations and light distribution issues, ensuring reliable measurement results.
Implementation Method 1
scanning the formed image with an optical sensor
Implementation Method 2
scanning elements (photodiodes) are arrayed in the same direction as a nozzle array direction
Data Source
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AI summary
A printing apparatus (1) comprising: printing means (3, 30) for printing by discharging the ink from the plurality of orifices to a printing medium (504) conveyed in a second direction crossing the first direction, and printing an inspection pattern including a first patch and a second patch different in color or having the same color and different in density so as to extend in the first direction on the printing medium by the plurality of orifices; and scanning means (405) for scanning in the second direction and scanning the inspection pattern (901, 902, 903); wherein the scanning means scans the first patch by using a first detection element of the plurality of detection elements and scans the second patch by using a second detection element which is another element of the plurality of detection elements.