Transparent Belt Paper Position Sensing for Inkjet Printers
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Solution Overview
Problem
Inkjet printers with multiple print heads face challenges in achieving precise image registration and accurate sheet media transport due to translational and transverse movements, leading to potential paper jams, skewed images, and image distortion, especially when handling sheets with varying properties.
Innovation Solution
A printer system utilizing a continuous, transparent Mylar belt with electrostatic tacking and a series of through-beam optical sensors to accurately track and position sheet media, ensuring precise registration of images across multiple print heads by maintaining the sheet's position relative to the belt and adjusting for any transverse excursions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple print heads are used in the transport direction to achieve high sheet processing speeds and high colour density, then productivity and manufacturing precision are improved, but the complexity of the transport system increases and paper position control becomes more difficult
Solution Approach 1:
The patent replaces complex mechanical position sensing systems with a transparent belt and optical sensor system. The optical sensor detects paper position through the transparent belt, eliminating the need for complex mechanical encoders or position sensors on the belt itself, thus reducing mechanical complexity while maintaining high-speed operation
Solution Approach 2:
The transparent belt acts as an intermediary that allows optical sensors to detect paper position without direct mechanical contact. This intermediary approach simplifies the position sensing mechanism while enabling precise control of paper movement through multiple print heads
2Manufacturing precision
If multiple print heads are used to print images with large number of inks and greater ink thickness, then manufacturing precision and colour density are improved, but image registration accuracy becomes more difficult to maintain
Solution Approach 1:
The patent replaces mechanical position sensing with optical sensing through the transparent belt. Optical sensors detect paper position and timing, providing precise registration data without the complexity of mechanical encoders, thus maintaining image registration accuracy across multiple print heads
Solution Approach 2:
The optical sensors provide continuous feedback on paper position and timing to the control system. This feedback enables real-time adjustment of print head firing timing to maintain precise image registration across multiple print heads, compensating for any belt position variations
3Reliability
If vacuum systems or roller nips are used to hold sheet media to the belt, then sheet transport reliability is improved, but paper jams and lifting occur with sheets of varying properties
Solution Approach 1:
The patent replaces vacuum systems and roller nips with electrostatic tack and friction-based transport on a transparent belt. This substitution eliminates the mechanical pressure and vacuum systems that cause paper jams and lifting, while providing more uniform and adaptable sheet handling for varying sheet properties
Solution Approach 2:
The patent changes the transport mechanism from mechanical (vacuum/roller nip) to electrostatic and friction-based. This parameter change allows the system to handle varying sheet properties more effectively, as electrostatic tack and friction can adapt to different sheet weights, thicknesses, and surface characteristics without causing damage
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
Enables high-speed, accurate registration of multiple print heads with minimal image distortion, even with varying sheet properties, by maintaining precise control over sheet positioning and handling, thus preventing paper jams and ensuring consistent image quality.
Implementation Method 1
a series of through beam optical sensors operable to direct a sensing beam through the belt for sensing of the position of the transported sheet medium upon the sheet medium breaking the beam
Implementation Method 2
a charging means to charge the sheet medium to electrostatically tack the sheet medium to the belt
Data Source
AI summary
A printing apparatus has a print head and a transport mechanism including a continuous transparent belt for transporting a sheet medium past a print head. The apparatus includes a through optical sensor operable to direct a sensing beam through the belt for sensing the position of the transported sheet medium when the sheet medium breaks the beam.