Printing Apparatus Light Intensity Gradient Control
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Solution Overview
Problem
Conventional ink-jet printers using photo-curing clear ink often experience line or streak formation due to uneven light irradiation, particularly near the downstream end in the sub-scanning direction, leading to differences in ink curing and refractive indices.
Innovation Solution
A printing apparatus with a configuration that includes a first head with nozzles for discharging clear ink, a first irradiator with light sources arranged in a specific pattern, and a controller to adjust light intensities, ensuring that the light intensity from outer light sources is smaller than that from the inner light sources, thereby reducing the gradient of light intensity distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the light irradiation distribution waveform rises gradually from the upstream end and reaches maximum near the downstream end, then the clear ink can be cured effectively, but the light intensity falls steeply near the downstream end causing uneven curing and line/streak formation
Solution Approach 1:
The light source is divided into multiple independent light emitting elements arranged in a row. Each light emitting element can be controlled independently to emit light with different intensities, allowing the overall light distribution to be shaped into a bell curve pattern that provides uniform irradiation across the clear ink layer.
Solution Approach 2:
Different light emitting elements are controlled to emit light with different intensities based on their position. The control unit adjusts the intensity of each light emitting element so that the combined light distribution follows a bell curve pattern, with higher intensity in the middle region and lower intensity at the ends, ensuring uniform curing throughout the clear ink layer.
2Reliability
If the light intensity is increased near the downstream end to compensate for the steep fall, then curing is improved, but the gradient of light intensity increases causing more pronounced boundary reflections and lines
Solution Approach 1:
The control unit changes the intensity parameter of each light emitting element dynamically. By adjusting the intensity of light emitting elements in the middle region to be higher than those at the ends, the system creates a bell curve light distribution that maintains gentle gradients throughout, preventing sharp intensity changes that cause boundary reflections and lines.
3Device complexity
If a simple light source arrangement is used, then the device complexity is reduced, but the light intensity distribution becomes uneven causing lines and streaks in the clear ink
Solution Approach 1:
Multiple light emitting elements are arranged in a row and controlled independently to serve dual purposes: they provide the necessary light intensity for curing while simultaneously shaping the light distribution pattern. This multi-functional arrangement allows a single light source structure to achieve both adequate curing and uniform irradiation distribution.
Solution Approach 2:
The control unit receives image data and adjusts the intensity of each light emitting element based on the processing requirements. This feedback mechanism allows the system to adapt the light distribution pattern to match the clear ink layer characteristics, ensuring uniform curing while maintaining simple hardware architecture.
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 configuration effectively reduces the occurrence of lines or streaks in the clear ink by minimizing the gradient of light intensity distribution, ensuring a smoother curing process and reducing visible boundary reflections.
Implementation Method 1
a first head including a plurality of first nozzles configured to discharge a clear ink having photo-curing property to a printing medium; a first irradiator including a plurality of first light sources configured to irradiate the clear ink on the printing medium with a light
Data Source
AI summary
There is provided a printing apparatus including: a first head including first nozzles; a first irradiator including first light sources; and a controller. The first nozzles are arranged to constitute a nozzle row. The first light sources are arranged to constitute a light source row, and including an inner light source, and first and second outer light sources. The controller is configured to cause: the first head to execute a first discharging operation of discharging a clear ink to a printing medium; and the first irradiator to execute a first irradiating operation of irradiating the clear ink with a light. The controller is configured to make an intensity of the light, from each of the first and second outer light sources, with which the clear ink is irradiated smaller than an intensity of the light, from the inner light source, with which the clear ink is irradiated.