Encoder Mist Detection and Ejection Restriction in Liquid Printers
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Solution Overview
Problem
In liquid ejecting apparatuses, mist of liquid droplets floating in the housing without being attached to the print medium causes detection errors in encoders, leading to degraded image quality during printing due to incorrect ejection timing.
Innovation Solution
A liquid ejecting apparatus with an encoder that includes a scale and light emitting/receiving elements to detect positional changes, a signal generation section to create pulse signals for ejection timing, and an ejection restriction section that prevents ejection when the time length between pulses exceeds a threshold, thereby maintaining image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If liquid is continuously ejected to maintain productivity, then printing speed is improved, but detection error occurs due to mist attachment on encoder scale
Solution Approach 1:
The system continuously monitors the time length between pulses from the encoder and compares it against a threshold value. When the time length exceeds the threshold, indicating mist attachment on the scale, the system automatically restricts liquid ejection to prevent further contamination of the encoder, thereby maintaining measurement precision while resuming productivity when conditions improve.
Solution Approach 2:
The system uses its own operational parameters (pulse timing from encoder) to detect degradation in measurement precision and automatically adjusts its behavior (restricting ejection) to restore proper functioning, without requiring external intervention or separate monitoring systems.
2Manufacturing precision
If ejection timing is controlled based on encoder output, then ejection precision is improved, but image quality degrades when detection error occurs
Solution Approach 1:
The system continuously monitors the time length between pulses from the encoder and compares it against a threshold value. When the time length exceeds the threshold, indicating mist attachment on the scale, the system automatically restricts liquid ejection to prevent further contamination of the encoder, thereby maintaining measurement precision while resuming productivity when conditions improve.
Solution Approach 2:
The system takes preventive action by restricting liquid ejection before significant image quality degradation occurs. By detecting abnormal pulse timing in advance, the system prevents mist from accumulating further on the encoder scale, thereby protecting the reliability of the ejection timing control system.
3Reliability
If liquid ejection is restricted when detection error occurs, then image quality is maintained, but productivity decreases
Solution Approach 1:
The system implements periodic monitoring of encoder pulse timing and uses periodic restriction of liquid ejection only when necessary (when time length exceeds threshold). This allows the system to maintain high productivity during normal operation while periodically preventing image quality degradation when detection errors are detected, optimizing the balance between productivity and 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
The solution effectively restricts ink ejection when detection errors occur, preventing mist attachment to the encoder and ensuring accurate ejection timing, thus maintaining high image quality during printing.
Implementation Method 1
a light receiving element receiving light reflected by the scale
Implementation Method 2
a light receiving element receiving light transmitted through the scale in the light emitted from the light emitting element
Data Source
AI summary
A liquid ejecting apparatus includes an ejecting section configured to eject liquid to a print medium, a movement mechanism configured to change the relative positional relationship between the print medium and the ejecting section, an encoder configured to include a scale, a light emitting element emitting light, and a light receiving element receiving light reflected by the scale or light transmitted through the scale in the emitted light and configured to output information changed in accordance with a change in the positional relationship, a signal generation section configured to generate a pulse signal including a pulse prescribing a timing when the ejecting section ejects liquid based on the information, a measurement section configured to measure a time length between pulses included in the pulse signal, and an ejection restriction section configured to restrict ejection of liquid from the ejecting section when the time length is larger than a threshold value.