Paper Thickness Detection Using Transmitted and Reflected Light

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Solution Overview

Problem

Existing image forming apparatuses face challenges in accurately determining the thickness of printing paper due to the influence of smoothness and glossiness, which can lead to incorrect detection and potential apparatus malfunction, especially when using low-cost optical sensors.

Innovation Solution

The apparatus employs a light emitting part and optical sensors to measure transmitted and reflected light at different angles, calculating a thickness coefficient by normalizing the amounts of transmitted and reflected light, thereby calibrating the thickness determination and suppressing the effects of smoothness and glossiness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the amount of transmitted light is used to determine paper weight, then detection is simple, but detection accuracy deteriorates due to smoothness and glossiness

Engineering Contradiction:
Improvedetection system complexityVSAvoidweight detection accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent combines transmitted light detection and reflected light detection into a single integrated measurement system. By merging these two detection methods and processing their combined data, the system achieves accurate weight detection that is insensitive to paper surface properties like smoothness and glossiness.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent changes the measurement parameters from solely transmitted light intensity to a composite parameter that incorporates both transmitted light and reflected light characteristics. This parameter transformation enables the system to eliminate the influence of surface smoothness and glossiness on weight detection accuracy.

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If high-smoothness paper is detected using transmitted light, then detection is straightforward, but erroneous determination occurs due to decreased transmitted light

Engineering Contradiction:
Improvedetection process simplicityVSAvoidweight determination reliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent introduces reflected light as an intermediary measurement that mediates between the paper's surface properties and the weight determination. By using reflected light characteristics as an intermediate parameter, the system can compensate for the decreased transmitted light in high-smoothness paper and achieve reliable weight detection.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of manufacture

If low-cost optical sensors are used, then device cost is reduced, but detection accuracy is compromised due to surface property interference

Engineering Contradiction:
Improvedevice costVSAvoidthickness detection precision
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent creates a computational model that copies or simulates the behavior of expensive specialized sensors using standard optical sensors. By developing algorithms that process both transmitted and reflected light data, the system replicates high-precision detection capabilities using low-cost components.

Inventive Principle:
Principle #26Copying

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 allows for accurate and robust detection of printing paper thickness, even with low-cost optical sensors, by calibrating the change in transmitted light using the reflected light components, ensuring correct detection and reducing the impact of smoothness and glossiness.

Implementation Method 1

an optical sensor to irradiate light to a medium forming a toner image on a surface from the light emitting element and detect the amount of transmitted light transmitted through the medium

Methodology Applied
Scientific EffectLight transmission: Light

Implementation Method 2

detect the amounts of two or more reflected lights at different angles reflected from the medium

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP3511776B1Image forming device and image forming method
Publication Date: 2021.08.04 HEWLETT PACKARD DEVELOPMENT COMPANY LP
  • EP3511776B1 patent drawingFigure 1
  • EP3511776B1 patent drawingFigure 2
  • EP3511776B1 patent drawingFigure 3

AI summary

An image forming apparatus is disclosed. The image forming apparatus includes an image forming part to form an image on printing paper, a sensor part to irradiate light to the printing paper and detecting amount of transmitted light transmitted through the printing paper and amount of reflected light reflected from the printing paper at each of a plurality of positions, and a processor to determine a thickness of the printing paper on the basis of the amount of the transmitted light and the amounts of a plurality of reflected lights and control the image forming part on the basis of the determined thickness.