Ejector Alignment Using Collimated Light for Clear Drop Detection
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Solution Overview
Problem
Existing printing systems face difficulties in detecting and aligning ejectors that eject clear material drops, particularly on shiny or mirror-like surfaces, as the clear drops do not image well and are obscured by the background light, making it challenging to infer their positions and orientations.
Innovation Solution
A printing system comprising an ejector head with an array of ejectors, an actuator, photosensitive devices, and a controller, which uses a light source with a louver and light pipe to emit collimated light for improved detection of clear drops, allowing for the identification of misalignment distances and adjustment of ejector alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If clear material drops are ejected onto shiny or mirror-like surfaces, then the surface finish and gloss levels of the printed product are improved, but the detection of drop positions becomes difficult due to background light obscuration
Solution Approach 1:
A louver structure is introduced as an intermediary element between the light source and the clear drops. The louver directs light at a specific angle to illuminate the clear drops without causing excessive background reflection, enabling the photosensitive device to detect drop positions even on shiny surfaces. This mediator structure resolves the contradiction by controlling light interaction separately from the surface finish requirement.
2Manufacturing precision
If clear drops are used to adjust gloss levels and form optical structures, then the quality of the printed product is improved, but the clear drops do not image well making alignment verification difficult
Solution Approach 1:
The louver acts as a mediator that enables measurement of clear drops without altering their optical structure quality. By controlling the illumination angle, the louver allows the photosensitive device to capture images of clear drops for alignment verification while maintaining the drops' intended optical properties for the final product.
Solution Approach 2:
The system changes the illumination parameter (light angle) to enable detection of clear drops. By adjusting the angle at which light strikes the clear drops through the louver structure, the system makes the drops visible to the photosensitive device without changing the drops' material properties or their intended function in the final product.
3Device complexity
If conventional light sources are used without directional control, then the system complexity is reduced, but the detection of clear drops on shiny surfaces is obscured by background light
Solution Approach 1:
The louver serves as a relatively simple intermediary structure that directs light from a conventional light source at a specific angle. This approach maintains relatively low system complexity while effectively enabling clear drop detection on shiny surfaces by controlling the path of light between the source and the detection plane.
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 effective detection and alignment of ejectors that eject clear material drops on shiny or mirror-like substrates, enhancing the precision of drop registration and surface finish in 2D and 3D printing systems.
Implementation Method 1
a light emitting diode (LED) that directs light into one end of the light pipe to enable light to be emitted from the openings in the light pipe and pass through the louver
Implementation Method 2
a plurality of photosensitive devices, each photosensitive device being configured to generate an electrical signal that corresponds to an amount of light received by the photosensitive device
Data Source
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AI summary
A printer is configured with an optical sensor that enables dashes in a test pattern formed with clear drops on a mirror-like surface to be detected and their positions identified. The optical sensor includes a louver positioned adjacent to a light source to limit and collimate an amount of light emitted by the light source onto each portion of the test pattern. The limiting of the light facilitates the processing of the image data generated by a plurality of photodevices that receive the specular light reflections from the mirror-like substrate and the test pattern to identify the positions of the dashes. These identified positions are compared to expected positions to identify misalignment distances that can be used to adjust ejector head alignment and timing of the firing signals to the ejector head that ejects clear drops.