Reflected Light Intensity Detection for Non-White Substrates

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Solution Overview

Problem

In printing apparatuses, detecting light reflected from substrates of non-white colors is challenging due to absorption, making it difficult to determine the appropriate light source for alignment and print head positioning.

Innovation Solution

A method that involves depositing a patch of print agent onto the substrate, directing radiation from multiple light sources with different wavelengths, measuring the intensity of reflected light, and selecting the source that produces the greatest contrast between the substrate and the print agent, ensuring optimal detection and alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a single light source is used for detection, then the device complexity is reduced, but the measurement precision deteriorates when printing on non-white substrates due to light absorption

Engineering Contradiction:
Improvedetection of reflected lightVSAvoidarrangement of light sources
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system dynamically selects which light source to use based on the substrate color being detected. The processor determines the substrate color and selectively activates the appropriate light source wavelength, making the system adaptive rather than static. This resolves the contradiction by providing high measurement precision for different substrate types without requiring all light sources to be active simultaneously, thus managing device complexity.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the parameter of light wavelength by selecting different light sources from the plurality available. Each light source emits a specific wavelength range, and the processor selects the optimal wavelength based on the substrate color to maximize reflected light detection. This parameter change allows precise measurement across different substrate types without increasing the physical complexity of the detection arrangement.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If multiple light sources with different wavelengths are used, then the adaptability to different substrate colors is improved, but the device complexity increases

Engineering Contradiction:
Improvedetection on various substrate colorsVSAvoidplurality of light sources
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

A single detector arrangement serves multiple functions by detecting reflected light from substrates of different colors. The system uses a plurality of light sources with different wavelengths, where each light source can be selected based on the substrate color, making the detection system universal for various printing applications. This multi-functionality achieves high adaptability without proportionally increasing complexity, as one detector handles all detection tasks.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system dynamically selects which light source to use based on the substrate color being detected. The processor determines the substrate color and selectively activates the appropriate light source wavelength, making the system adaptive rather than static. This resolves the contradiction by providing high measurement precision for different substrate types without requiring all light sources to be active simultaneously, thus managing device complexity.

Inventive Principle:
Principle #15Dynamics

3Measurement precision

If light sources are selected without considering substrate color, then the ease of operation is improved, but the measurement precision deteriorates due to light absorption

Engineering Contradiction:
Improveintensity of reflected lightVSAvoidlight source selection
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The system performs self-service by automatically determining the substrate color and selecting the appropriate light source without requiring manual intervention. The processor analyzes the substrate color characteristics and autonomously selects the optimal light source wavelength to maximize reflected light detection. This automation maintains ease of operation while achieving high measurement precision, as the system handles the complex selection process itself.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system uses feedback from the detected substrate color to select the appropriate light source. The processor determines the substrate color based on reflected light characteristics and uses this information to select the optimal light source wavelength. This feedback loop ensures measurement precision is optimized for each substrate type while maintaining ease of operation, as the system automatically adjusts based on real-time 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 approach allows for effective selection of the appropriate light source based on the substrate color, enhancing print management and alignment operations, especially when printing on non-white or translucent substrates, by maximizing the intensity difference between the substrate and the print agent.

Implementation Method 1

a sensor to detect light from each light source that has been reflected from the printable medium

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 2

reflected light of some colors (i.e. light of some wavelengths) may not be easy to detect by the detector, for example due to the light being absorbed by the substrate

Methodology Applied
Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Data Source

PatentEP3774345B1Determining reflected light intensities of light sources
Publication Date: 2023.12.20 HEWLETT PACKARD DEVELOPMENT COMPANY LP
  • EP3774345B1 patent drawingFigure 1
  • EP3774345B1 patent drawingFigure 2
  • EP3774345B1 patent drawingFigure 3

AI summary

The method may comprise depositing print agent of a particular color onto a printable substrate to form a patch of print agent. It may comprise directing radiation from a plurality of radiation sources onto the patch of print agent and onto the printable substrate. Also, may comprise detecting, using a sensor, radiation from the plurality of radiation sources which has been reflected from the printable substrate and radiation from the plurality of radiation sources which has been reflected from the patch of print agent. Further, may comprise measuring, for each of the plurality of radiation sources, an intensity of the radiation reflected from the printable substrate and an intensity of the radiation reflected from the patch of print agent. Also, may comprise selecting, based on the measured intensities, a radiation source of the sources to be associated with the print agent of the particular color.