Specular Reflection Distance Sensor Alignment for Print Head Height Control
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Solution Overview
Problem
Existing recording devices with specular reflection type distance sensors face challenges in accurately measuring distance to printing media with uneven surfaces, as light reflection can occur at positions offset from the target, leading to measurement deviations and printing density variations.
Innovation Solution
The printing device incorporates a specular reflection type distance sensor with a light-emitting element and light-receiving element aligned in the moving direction of the carriage, ensuring that light is reflected off the target position on the printing medium even when the surface is uneven, and a diffuse reflection type sensor with elements aligned orthogonally to the moving direction to minimize measurement errors due to diffuse reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a specular reflection type distance sensor is used to measure distance to printing medium, then measurement speed and precision are improved, but measurement accuracy deteriorates when the printing medium surface is uneven
Solution Approach 1:
The patent changes the alignment dimension of the light-emitting and light-receiving elements. Instead of aligning them in the conveying direction (one dimension), they are aligned in the moving direction of the carriage (another dimension). This dimensional change allows the sensor to maintain accurate distance measurement on uneven surfaces by ensuring light reflects off the target position rather than offset positions.
2Device complexity
If the light-emitting element and light-receiving element are aligned in the conveying direction, then the sensor structure is simplified, but light reflects off offset positions on uneven surfaces causing measurement errors
Solution Approach 1:
The patent resolves this contradiction by changing the alignment dimension from the conveying direction to the moving direction of the carriage. This maintains a relatively simple sensor structure while eliminating the measurement error caused by light reflecting off offset positions on uneven surfaces.
3Measurement precision
If the light-emitting element and light-receiving element are aligned in the moving direction of the carriage, then measurement accuracy on uneven surfaces is improved, but the sensor configuration becomes more complex
Solution Approach 1:
The patent achieves improved measurement accuracy on uneven surfaces by aligning the light-emitting and light-receiving elements in the moving direction of the carriage. While this does increase configuration complexity compared to orthogonal alignment, it resolves the critical measurement accuracy issue, and the complexity is justified by the significant improvement in printing quality and measurement reliability.
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 allows for precise distance measurement and consistent printing density across uneven printing media surfaces, reducing measurement errors and maintaining printing quality by adjusting ink ejection based on real-time sensor data.
Implementation Method 1
The first distance sensor is a specular reflection type distance sensor
Data Source
AI summary
A printing device includes a head and a carriage. The head has a nozzle. The head is configured to eject liquid from the nozzle toward a printing medium. The carriage is configured to move the head in a first direction. The carriage includes a first distance sensor. The first distance sensor is configured to measure a distance between the head and the printing medium. The first distance sensor is a specular reflection type distance sensor. The first distance sensor includes a light-emitting element and a light-receiving element. The light-emitting element and the light-receiving element are aligned in the first direction.