Movable Direct Sensor for Inkjet Conveyance Accuracy
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Solution Overview
Problem
Inkjet printing apparatuses face challenges in maintaining high conveyance accuracy due to sensing disabled periods when the sheet edge deviates from the fixed sensing position, leading to inconsistent image quality, especially during multipass printing methods.
Innovation Solution
The printing apparatus incorporates a movable direct sensor that can selectively position itself to either side of the sheet conveyance direction, allowing continuous sensing of sheet movement by using multiple openings and a movement mechanism, thereby reducing sensing disabled periods and ensuring accurate conveyance control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed direct sensor is used for sheet conveyance detection, then the sensor structure is simple, but the sensing disabled period increases when sheet edges deviate from the sensing position
Solution Approach 1:
The patent applies the dynamics principle by making the direct sensor movable instead of fixed. The sensor can dynamically adjust its position along the sheet conveyance direction to track the sheet edges during multipass printing, thereby eliminating the sensing disabled period while maintaining relatively simple device structure.
Solution Approach 2:
The patent introduces movement freedom in the sheet conveyance direction (adding a dimensional aspect) to the originally fixed sensor. This allows the sensor to access different positions along the conveyance path, converting a single-point fixed sensing into a multi-position trackable sensing system.
2Reliability
If a movable direct sensor is used to reduce sensing disabled period, then the sensing coverage is improved, but the device complexity increases
Solution Approach 1:
The patent replaces complex mechanical sensing systems with a simplified movable sensor approach. Instead of using multiple fixed sensors or complex mechanical detection mechanisms, a single direct sensor is made movable to achieve continuous edge detection, reducing overall system complexity while improving reliability.
3Productivity
If the sheet conveyance speed is increased for higher productivity, then the printing speed improves, but the conveyance accuracy decreases leading to image quality defects
Solution Approach 1:
The patent implements feedback control by using the movable direct sensor to continuously detect actual sheet conveyance position and amount. This real-time feedback information is used to correct and adjust conveyance control, maintaining high conveyance accuracy even at increased printing speeds, thereby preventing image quality defects.
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 solution enables improved image quality by maintaining accurate conveyance control and reducing defects such as white or black streaks, even during one-way printing, while allowing for higher printing speeds and increased sheet conveyance amounts without compromising image quality.
Implementation Method 1
a direct sensor including a light-emitting device that emits light toward the sheet, an image pickup device that images the sheet surface
Data Source
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AI summary
A printing apparatus including a conveyance mechanism (3) configured to convey a sheet in a predetermined direction, a printing unit (50, 2000, 7) configured to print an image on the sheet, a direct sensor (1000, 2003) having an image pickup device (1004) configured to image the sheet, which is used to sense movement of the sheet by signal processing of an output from the image pickup device. A movement mechanism (1014, 2006) is configured to move the image pickup device in a direction including a component of the predetermined direction, and a control unit (10) is configured to control the conveyance mechanism (3), the printing unit (50, 2000, 7), and the movement mechanism.