Liquid Ejection Timing Adjustment via Spotlight Edge Detection
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Solution Overview
Problem
Existing liquid-ejecting image forming apparatuses face challenges in accurately adjusting the ejection timing of liquid droplets due to instability in detecting the edge position of test patterns on materials with low reflectance, such as tracing paper, leading to inaccuracies in nozzle positioning and image formation.
Innovation Solution
The apparatus employs a reading unit with a light emitting and receiving system, relative movement, and signal correction processes to subtract background noise and stabilize the detected voltage, allowing for accurate alignment of local maxima and minima to determine the test pattern edge position, thereby correcting the ejection timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light receiving unit detects reflected light from a test pattern on low-reflectance material, then the edge position can be determined, but the detected voltage becomes unstable leading to measurement inaccuracies
Solution Approach 1:
A spotlight is introduced as an intermediary element between the light receiving unit and the test pattern. The spotlight concentrates the irradiated light into a focused beam that scans across the test pattern, enhancing the light interaction with the pattern features. This intermediary light concentration mechanism enables stable voltage detection even on low-reflectance materials by ensuring sufficient light intensity reaches the pattern and reflects back to the sensor.
Solution Approach 2:
The system changes the physical parameter of light distribution by using a spotlight to concentrate and focus the light beam. Instead of using diffuse illumination, the spotlight creates a concentrated scanning beam that moves across the test pattern. This parameter change in light concentration and scanning motion enables reliable edge detection by creating distinct voltage transitions when the spotlight scans across pattern edges, even on materials with low reflectance.
2Measurement precision
If the spotlight scans the test pattern to detect edge position, then the edge can be identified through voltage changes, but the method becomes ineffective when the sheet material has low reflectance
Solution Approach 1:
The spotlight serves as an intermediary that actively concentrates light onto the test pattern features. By focusing the light beam and scanning it across the pattern, the system compensates for the low reflectance of the sheet material. The concentrated spotlight ensures sufficient light intensity interacts with the pattern and returns to the light receiving unit, enabling edge detection despite the material's low reflectance properties.
Solution Approach 2:
The spotlight scans the test pattern in a periodic scanning motion, creating regular voltage fluctuations as it moves across the pattern features. This periodic scanning action generates characteristic voltage patterns with distinct maxima and minima that correspond to pattern edges. The periodic nature of the scanning enables reliable edge position determination through signal processing of the voltage waveform, even when the overall signal level is low due to material reflectance characteristics.
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 approach enables precise specification of the test pattern edge position even on low-reflectance materials, enhancing the accuracy of liquid droplet ejection timing adjustments and improving image formation quality.
Implementation Method 1
a light emitting unit which irradiates a light onto the recording medium, and a light receiving unit which receives a reflected light from the recording medium
Data Source
AI summary
An image forming apparatus is disclosed which reads a test pattern formed by ejecting liquid droplets onto a recording medium to adjust an ejection timing of the liquid droplets. The image forming apparatus includes a reading unit; a relative movement unit; a second detected data obtaining unit; a first detected data obtaining unit; a subtraction processing unit which subtracts a value comparable to a local minimum value of first detected data sets from each of the first detected data sets and second detected data sets; and a signal correction unit which calculates a proportion of the subtracted first detected data sets relative to the subtracted second detected data sets to align a local maximum value of the first detected data sets such that it is generally constant.