Inkjet Printer Optical Path Splitting for Droplet Detection
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Solution Overview
Problem
Inkjet printers face challenges in accurately judging the ejection state of ink due to difficulties in distinguishing between changes in light reception caused by ink droplets and noise, especially when droplet sizes are small relative to the light beam.
Innovation Solution
The implementation of an inkjet printer design that includes a light emitting element, a beam splitter, and two light receiving elements, with a subtraction circuit to calculate the difference between light received through paths passing through and not passing through the ink's flight area, allowing for improved judgment of ink ejection state by reducing noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single light receiving element is used to detect ink droplets, then the device complexity is low, but the measurement precision deteriorates because changes in received light due to small droplets cannot be distinguished from noise
Solution Approach 1:
The light receiving system is segmented into multiple light receiving elements (first light receiving element and second light receiving element) that receive light through different optical paths. The first optical path passes through the flying area where ink droplets travel, while the second optical path does not pass through the flying area. By segmenting the detection system and comparing signals from different paths, the invention isolates droplet-related light changes from noise, thereby improving measurement precision without excessive complexity increase.
Solution Approach 2:
The patent introduces a subtraction circuit as an intermediary component that processes signals from multiple light receiving elements. This intermediary subtracts the signal from the second light receiving element (which receives only background light) from the signal of the first light receiving element (which receives both background light and droplet-related light changes). This intermediary processing step effectively removes noise while preserving droplet detection capability, improving measurement precision with minimal added complexity.
2Measurement precision
If the light beam size is reduced to match small droplet sizes, then the measurement precision improves, but the reliability deteriorates because noise becomes more significant relative to the already small signal
Solution Approach 1:
The invention extracts the noise component from the total light signal by using a dedicated optical path (second optical path) that does not pass through the flying area. The second light receiving element captures only background light and noise without droplet interference. By extracting this noise component and subtracting it from the first light receiving element's signal, the system reliably isolates the droplet-related signal even when droplets are small, thereby maintaining both measurement precision and reliability.
Solution Approach 2:
The system implements a feedback mechanism where the signal from the second light receiving element (representing background noise) is continuously fed back to the subtraction circuit. This feedback loop allows the system to dynamically compensate for background light variations and noise, ensuring stable and reliable droplet detection judgments even when working with small droplet signals. The feedback ensures that only genuine droplet-related light changes trigger detection responses.
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 solution enhances the accuracy of ink ejection state judgment by isolating the signal corresponding to ink droplets from noise, even when droplet sizes are smaller than the light beam, thereby improving the reliability of inkjet printing operations.
Implementation Method 1
a light emitting element configured to emit light
Implementation Method 2
a beam splitter configured to split an optical path, which is a path of light emitted from the light emitting element, into a first optical path and a second optical path
Implementation Method 3
an amount of light when the droplet passes through the light beam is measured by the light receiving element
Data Source
AI summary
An inkjet printer is provided that includes: a head including a nozzle, a light emitting element, a beam splitter configured to split an optical path into first and second optical paths, first and second light receiving elements configured to receive light passing through the first and second optical paths, respectively, a subtraction circuit configured to obtain a difference between an amount of received light by the first light receiving element and an amount of received light by the second light receiving element, and a controller. The first optical path is provided so as to pass through a flying area in which ink ejected from the nozzles flies, and the second optical path is provided so as not to pass through the flying area. The controller is configured to execute to judge an ejection state of ink by the head based on the difference.