Rhombic Aperture Optical Droplet Detection
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Solution Overview
Problem
Existing image-forming apparatuses face detection accuracy issues due to increased noise from diffracted light when using a square aperture opening, leading to reduced accuracy in detecting the state of discharged liquid droplets.
Innovation Solution
A device with a light emitter and receiver arrangement featuring a rhombic or rectangular aperture opening, where the light-receiving surface is displaced along the diagonal lines of the aperture opening, reducing offset light incidence and improving signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a square aperture opening is used in the light emitter, then the device structure is simple and easy to manufacture, but diffracted light increases in the direction of line segments connecting middle points of parallel sides, causing increased noise and reduced detection accuracy
Solution Approach 1:
The patent applies asymmetry by changing the aperture opening shape from a conventional square to a rhombic shape. This asymmetric configuration causes diffracted light to be generated in diagonal directions rather than along the axis-connecting directions of a square aperture. By positioning the light-receiving surface to receive scattered light from liquid droplets while avoiding the diagonal diffraction directions, the patent reduces noise from diffracted light and improves detection accuracy while maintaining manufacturing simplicity.
2Object-affected harmful factors
If the light-receiving surface is displaced in the feeding direction of the recording medium, then mist attachment to the light-emitting element and collimator lens is reduced, but diffracted light may incident on the light-receiving surface as offset light, increasing noise
Solution Approach 1:
The patent uses the rhombic aperture shape to create asymmetric diffraction patterns where the main diffraction directions are along the diagonals. By strategically positioning the light-receiving surface at an offset from the optical axis in the feeding direction, the patent achieves two goals: (1) the offset position avoids direct incidence of diffracted light along the diagonal directions, reducing noise; and (2) the positioning still allows reception of scattered light from liquid droplets while being less susceptible to mist attachment compared to on-axis positioning.
Solution Approach 2:
The patent addresses the mist attachment problem by utilizing the feeding direction dimension. By displacing the light-receiving surface in the feeding direction (orthogonal to the width direction where nozzles are arranged), the patent creates spatial separation from the region where mist tends to accumulate near the nozzles and light-emitting element, thereby reducing mist attachment while managing diffracted light through the rhombic aperture geometry.
3Device complexity
If the light-receiving surface is positioned on the optical axis of the light emitter, then the optical path is simple, but diffracted light incidents directly on the light-receiving surface, increasing noise and reducing detection accuracy
Solution Approach 1:
The patent employs the rhombic aperture shape to redirect diffracted light away from the optical axis. The asymmetric rhombic geometry causes diffraction maxima to occur along diagonal directions rather than perpendicular to the aperture sides as with a square aperture. By positioning the light-receiving surface at an offset from the optical axis, the patent ensures that diffracted light does not directly incident on the receiver, reducing noise while maintaining a relatively simple optical path configuration.
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
Enhances detection accuracy of discharged liquid droplets by minimizing noise and preventing mist attachment to the light-receiving element and lens, thereby improving the overall detection process.
Implementation Method 1
the light emitter includes a light-emitting element, a condenser lens which condenses light from the light-emitting element to emit as a light beam
Implementation Method 2
a condenser lens which condenses light from the light-emitting element to emit as a light beam
Implementation Method 3
when the light beams pass through the aperture opening, diffracted light with the light beams is generated in the direction of the line segments connecting respective middle points of the parallel two sides of the aperture opening
Implementation Method 4
This device receives scattered light of light beams with the light receiver, which scatters forward in the traveling direction of the light beams due to the existence of the liquid droplets
Data Source
AI summary
A device for detecting a state of a discharged liquid droplet includes a plurality of nozzles which is arranged in a width direction of a recording medium orthogonal to a feeding direction of the recording medium to discharge a liquid droplet toward the recording medium, a light emitter which is provided on one side of the recording medium in the width direction orthogonal to the feeding direction of the recording medium, and a light receiver which is provided on the other side of the recording medium in the width direction, wherein the light emitter includes a light-emitting element, a condenser lens which condenses light from the light-emitting element to emit as a light beam, and an aperture stop member including an aperture opening through which the light beam passes.