Elastic Wave Distance Detection for Print Head Impact Prevention
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Solution Overview
Problem
Ink jet printing apparatuses face issues with creases and cockling in printing media due to transport shifts, leading to potential carriage impacts, which existing optical detection methods struggle to accurately prevent, especially with transparent media and surface inclinations.
Innovation Solution
A printing apparatus utilizing an elastic wave radiation unit to measure the time of arrival of reflected elastic waves, allowing for precise detection of the distance between the carriage and printing medium, with a control unit stopping movement when the distance falls below a defined minimum, thus preventing impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an optical detection type sensor is used to detect printing medium uplift, then the carriage movement can be stopped to prevent impact, but false detections occur due to surface inclination and transparent media causing the system to stop unnecessarily
Solution Approach 1:
The patent replaces the optical detection system with an elastic wave-based detection system. The elastic wave sensor emits waves toward the printing medium surface and detects reflected waves to measure the gap distance. This mechanical/acoustic approach is insensitive to surface inclination and transparent media, eliminating false detections while maintaining reliable impact prevention.
Solution Approach 2:
The patent changes the detection parameter from optical reflection intensity to elastic wave time-of-flight. By measuring the time for elastic waves to travel to the printing medium surface and back, the system obtains accurate gap distance measurements that are not affected by surface inclination or media transparency, thereby resolving the false detection issue.
2Reliability
If the carriage is stopped frequently to prevent impact, then printing medium damage is avoided, but printing productivity decreases
Solution Approach 1:
The patent implements a feedback control system using elastic wave sensing to continuously monitor the gap between the carriage and printing medium. The control unit adjusts carriage speed dynamically based on real-time gap measurements, stopping only when necessary and maintaining normal speed when the gap is safe, thereby preserving productivity while ensuring printing quality.
Solution Approach 2:
The system transitions from static carriage movement to dynamic speed adjustment based on real-time elastic wave measurements. The carriage speed is continuously adapted according to the detected gap distance, allowing the system to maintain optimal speed when safe and prevent impacts only when necessary, thus balancing productivity and quality.
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 effectively prevents carriage impacts by accurately detecting distance changes, even with transparent media, and allows continuous printing when safe, enhancing printing quality and throughput.
Implementation Method 1
an elastic wave radiation unit that radiates elastic waves, which are pulses or burst waves in which a radiation direction is defined, toward the target printing surface, a reception unit that receives the elastic waves that are radiated from the elastic wave radiation unit and reflected by the target printing surface
Implementation Method 2
a control unit which measures the time of arrival taken for elastic waves that are radiated from the elastic wave radiation unit to arrive at the reception unit
Data Source
AI summary
A printing apparatus includes a print head that forms an image on a target printing surface of a printing medium by relatively moving with respect to the printing medium, an elastic wave radiation unit that radiates elastic waves, in air toward the target printing surface, a reception unit that receives the elastic waves that are radiated from the elastic wave radiation unit and reflected by the target printing surface, and a control unit which measures the time of arrival taken for elastic waves, and stops relative movement when the time of arrival is shorter than a defined time, in which the defined time is a time of arrival in which a distance from the print head to the printing medium and the distance from the elastic wave radiation unit to the printing medium to an allowable minimum distance between the print head and the printing medium.