Optical Pen-to-Paper Spacing Detection in Printers
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Solution Overview
Problem
Ink jet printers face challenges in maintaining consistent pen-to-paper spacing (PPS) over their lifetime due to factors like paper jams and handling, leading to variations in print quality, especially in high-end printers that require precise control for high-resolution images. Current methods for checking PPS uniformity are complex, time-consuming, and require skilled technicians with expensive external tools.
Innovation Solution
An automatic system and method using an optical reflectance sensor attached to the print head carriage, which measures absolute and relative PPS internally, allowing for accurate detection and adjustment without external tools, utilizing a test pattern and mathematical calibration to compensate for sensor height and media non-uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current manual methods are used to check PPS uniformity, then measurement precision can be achieved, but device complexity and time consumption increase significantly
Solution Approach 1:
The printing system performs self-diagnosis by automatically measuring PPS uniformity using an optical sensor integrated into the print head carriage. The system prints test patterns and analyzes them to detect spacing variations without requiring external measurement tools or skilled technicians, enabling the system to service itself.
Solution Approach 2:
The patent replaces manual mechanical measurement methods with an optical measurement system. An optical sensor detects the reflected light from the test pattern to determine PPS uniformity, eliminating the need for physical measuring tools and manual intervention while maintaining measurement precision.
2Measurement precision
If manual PPS checking methods are used, then accurate measurement is possible, but loss of time increases significantly
Solution Approach 1:
The optical sensor continuously monitors PPS uniformity during normal printing operations rather than requiring separate manual measurement sessions. The system performs automated measurements during print head movement, eliminating downtime and integrating measurement into the continuous printing process.
Solution Approach 2:
The system automatically performs PPS measurement and diagnosis without requiring technician intervention. The automated test pattern printing and optical analysis occur routinely, eliminating the time loss associated with scheduling and performing manual measurements by skilled technicians.
3Difficulty of detecting and measuring
If external measurement tools are used, then measurement capability is provided, but device complexity and cost increase
Solution Approach 1:
The optical sensor and test pattern system serve multiple functions: they are used for both printing and for measuring PPS uniformity. This multi-functionality eliminates the need for separate external measurement tools, reducing overall system complexity and cost while maintaining measurement capability.
Solution Approach 2:
The printing system includes its own self-contained measurement capability through integrated optical sensors and test pattern generation. This eliminates dependence on external measurement tools and specialized equipment, reducing system complexity and operational costs.
4Measurement precision
If manual measurement methods are used, then PPS can be measured, but ease of operation decreases due to specialized training requirements
Solution Approach 1:
The system performs automated PPS measurement and diagnosis without requiring skilled technician intervention. The automated test pattern printing, optical sensing, and analysis eliminate the need for specialized training, making the operation simple and accessible to end users.
Solution Approach 2:
The patent replaces complex manual measurement procedures with automated optical sensing and digital analysis. This substitution eliminates the need for specialized training in manual measurement techniques, significantly improving ease of operation while maintaining measurement precision through computational analysis.
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 simplifies and accelerates PPS measurement, providing accurate and cost-effective uniformity checks, reducing maintenance costs and improving print quality by allowing for internal calibration in stand-alone printers, such as self-service photo printing kiosks, without the need for specialized training or equipment.
Implementation Method 1
An automatic system and method using an optical reflectance sensor attached to the print head carriage, which measures absolute and relative PPS internally
Data Source
AI summary
A system for detecting pen-to-paper spacing (PPS) in a printing system having a pen attached to a moveable print head positioned near a print media position, includes a test pattern, at the print media position, a sensor device, attached to the print head, and a controller. The test pattern includes printed lines having a line dimension, and the sensor device is positioned to shine light upon, and detect light reflected from the test pattern as the print head scans across the test pattern. The controller is connected to receive reflectance signals from the reflectance sensor, and configured to determine line dimensions in the test pattern and compare said line dimensions with predetermined line dimension values for the test pattern to determine variation in the PPS.