Off-Axis Droplet Detection for Inkjet Nozzle Reliability
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Solution Overview
Problem
Inkjet printing devices face reliability issues due to nozzle malfunctions, such as resistive element failures, blockages in ink supply lines, firing chambers, and nozzles, which affect the quality of printed images or objects.
Innovation Solution
A droplet detection apparatus using a light emitter with a spatial intensity distribution profile and a light detector positioned to receive the peak intensity away from the optical axis, allowing for effective detection of droplet ejection from nozzles, even in large-scale printing devices where scalability and interference mitigation are challenges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional light emitter with peak intensity on the optical axis is used, then the light detection is simple, but interference between multiple detection points occurs and detection precision deteriorates in large-scale printing devices
Solution Approach 1:
The patent applies local quality by positioning the light detector to receive light at a specific location (peak intensity point) that is offset from the optical axis. This creates a localized detection zone with optimal signal characteristics, improving droplet detection precision while maintaining a relatively simple overall system structure. The detector is positioned to receive light at coordinates (x, y, z) where the spatial intensity distribution reaches its maximum, rather than on the central optical axis.
2Productivity
If multiple nozzles are used to increase productivity, then printing output increases, but nozzle malfunction impact on quality increases
Solution Approach 1:
The patent implements feedback by using the light detector to monitor droplet ejection from multiple nozzles and providing information about nozzle performance. The detector receives light that has interacted with droplets, and this information can be used to identify malfunctions in individual nozzles, allowing for real-time quality control and maintaining consistent printing quality across multiple nozzles operating in parallel.
3Measurement precision
If the light detector is positioned on the optical axis, then the alignment is simple, but the detection precision deteriorates due to interference and scattered light
Solution Approach 1:
The patent applies dimensionality change by moving the light detector from the central optical axis (one-dimensional alignment) to an off-axis position in three-dimensional space. The detector is positioned at specific coordinates (x, y, z) where it receives light at the peak intensity point of the spatial intensity distribution. This spatial repositioning improves detection precision by avoiding interference and scattered light while maintaining reasonable alignment requirements through defined geometric relationships.
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 reliable detection of droplet ejection from multiple nozzles, ensuring consistent printing quality by identifying and addressing potential malfunctions, and allowing for modular scalability in large printing systems.
Implementation Method 1
a light emitter to emit light along an optical axis, the light having a spatial intensity distribution profile with a peak that is non-coincident with the optical axis; and a light detector located relative to the light emitter such that, in use, the peak of the spatial intensity distribution profile is incident on the light detector
Implementation Method 2
determine whether a droplet is present along the droplet trajectory on the basis of the signal generated by the light detector
Data Source
AI summary
Apparatus to detect droplets and methods for detecting droplets are described. The apparatus comprise a light emitter and a light detector. The light emitter is to emit light along an optical axis, the light having a spatial intensity distribution profile with a peak that is non-coincident with the optical axis. The light detector is located relative to the light emitter such that, in use, the peak of the spatial intensity distribution profile is incident on the light detector.