Optical Sensor Reflectance Stabilization in Liquid Ejecting Apparatus
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Solution Overview
Problem
The accuracy of detecting the edge position of a sheet of paper in liquid ejecting apparatuses is compromised due to changes in the reflectance of the reference reflecting surface caused by ink mist and paper dust, leading to improper threshold value settings and reduced sensitivity of optical sensors over time.
Innovation Solution
A carriage with a liquid ejecting head and an optical sensor, featuring a coverable reflecting part protected from debris, allows for stable reflectance measurement and sensitivity adjustment, ensuring accurate edge detection despite progressive deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the optical sensor is exposed to detect edge position continuously, then edge detection functionality is maintained, but the sensor becomes sullied by ink mist and paper dust causing gradual decline in light reception and detection accuracy
Solution Approach 1:
The patent extracts the harmful environment (ink mist and paper dust) from the sensor area by introducing a partition wall that physically separates the sensor from the liquid ejecting head region. This allows the sensor to be protected from sullying while maintaining its detection function.
Solution Approach 2:
The partition wall acts as an intermediary barrier between the optical sensor and the harmful substances (ink mist, paper dust). It mediates the interaction by blocking the direct path of contaminants while allowing light to reach the sensor, thus protecting the sensor without interfering with its detection capability.
2Measurement precision
If the threshold value is set based on initial sensor performance, then initial edge detection accuracy is achieved, but detection accuracy deteriorates over time due to sensor aging and sullying
Solution Approach 1:
The patent performs preliminary actions by setting multiple threshold values in advance corresponding to different sensor performance levels. This allows the system to prepare for future degradation and switch to appropriate threshold values before detection accuracy is significantly impacted by aging or sullying.
Solution Approach 2:
The system incorporates feedback mechanisms to monitor sensor performance and adjust threshold values dynamically. By comparing detection results and monitoring light reception levels, the system can identify when sensor degradation occurs and switch to compensated threshold values to maintain detection accuracy throughout the sensor's operational life.
3Object-affected harmful factors
If a movable shutter is used to protect the sensor, then sensor protection from floating matter is achieved, but device complexity increases
Solution Approach 1:
Instead of using a complex movable shutter mechanism, the patent extracts the protection function by introducing a simple partition wall that is fixed or easily integrated into the carriage structure. This removes the need for additional actuators and control mechanisms while still achieving sensor protection.
Solution Approach 2:
The partition wall provides localized protection only in the specific area where the optical sensor is positioned, rather than covering the entire sensor assembly with a complex shutter mechanism. This local approach reduces overall device complexity while maintaining effective protection.
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
The solution maintains stable reflectance and enhances measurement sensitivity, ensuring accurate edge position detection even with progressive sensor degradation, avoiding unnecessary movement and maintaining throughput.
Implementation Method 1
an optical sensor which is provided to the carriage and has a light-emitting unit capable of irradiating light toward the medium and a light-receiving unit for receiving reflected light of the light and outputting an output value corresponding to an amount of light received
Data Source
AI summary
This is to provide a liquid ejecting apparatus and a sensor sensitivity setting method in a liquid ejecting apparatus making it possible to keep low any fluctuations in the reflectance of a reflecting part used to measure the sensitivity of an optical sensor provided to a carriage, and to enhance the accuracy of measurement sensitivity, thus making it possible to ensure the required sensitivity even in spite of progressive deterioration of the optical sensor.