Printer Platen Edge Detection Threshold Determination

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Solution Overview

Problem

Existing printers lack a clear method for determining the threshold of detection for the edge of a printing medium, relying on ambiguous signal processing from optical sensors, which affects accurate edge detection and foreign substance identification.

Innovation Solution

A liquid ejecting apparatus with a platen featuring projections and a detector system that emits and receives light to generate detection signals, allowing a controller to determine a threshold value by averaging signal levels at multiple positions, and detect foreign substances based on signal levels indicative of their presence.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a threshold is set based on optical sensor output signal when sensing a protrusion on the platen, then edge detection capability is provided, but the method does not specify how to process the output signal to set the threshold

Engineering Contradiction:

Improveedge detection capabilityVSAvoidsignal processing complexity

Core Design Contradiction:

Ease of operationVSDifficulty of detecting and measuring

Solution Approach 1:

The patent segments the platen surface into multiple detection regions (first region with larger protrusions and second region with smaller protrusions) and obtains detection signals from multiple positions. This segmentation allows the system to process signals from different regions separately, making the threshold setting process more manageable and less complex while maintaining accurate edge detection capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary actions by obtaining detection signals from multiple positions on the platen before actually detecting the printing medium edge. These preliminary signals are used to determine an appropriate threshold value in advance, which simplifies the subsequent edge detection process and eliminates the need for complex real-time signal processing.

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If a single threshold value is used for edge detection, then the detection process is simple, but signal variation at different positions affects detection accuracy

Engineering Contradiction:

Improvedetection process simplicityVSAvoidedge detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent applies local quality by recognizing that different regions of the platen have different reflective properties. The first region with larger protrusions and the second region with smaller protrusions produce different signal levels. By obtaining detection signals from multiple positions and using these varied signals to determine the threshold, the system accounts for local variations in the platen surface while maintaining a single threshold value for the overall detection process.

Inventive Principle:

Principle #3Local quality

3Reliability

If the optical sensor detects protrusions on the platen to set threshold, then foreign substance detection is enabled, but signal levels at different positions make threshold determination difficult

Engineering Contradiction:

Improveforeign substance detectionVSAvoidthreshold determination accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent uses feedback by obtaining detection signals from multiple positions on the platen and using these signals to determine an appropriate threshold value. This feedback mechanism allows the system to adjust the threshold based on actual signal characteristics observed at different positions, improving both the accuracy of threshold determination and the reliability of foreign substance detection.

Inventive Principle:

Principle #23Feedback

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 method stabilizes edge detection and foreign substance identification by reducing signal variation, ensuring accurate threshold setting and improved operational reliability in printers.

Implementation Method 1

a light emitter operable to emit light toward the platen and a light receiver adapted to receive light reflected from the platen

Methodology Applied

Scientific EffectLight reflection: Reflection

Data Source

PatentUS7469984B2Method of determining threshold of detection for edge of printing medium, and printer operable to execute the same

Publication Date: 2008.12.30 SEIKO EPSON CORP

AI summary

A liquid ejecting head is operable to eject liquid toward a target medium. A platen opposes to the liquid ejecting head, and has a first region formed with a plurality of projections. A first detector includes a light emitter operable to emit light toward the platen and a light receiver adapted to receive light reflected from the platen. The first detector is operable to generate a detection signal in accordance with an amount of the light received by the light receiver. A controller is operable to obtain the detection signal at a plurality of positions in the first region to determine a threshold value of the detection signal for detecting whether the target medium exists on the platen.