Sheet Thickness Measurement via Light Propagation

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Solution Overview

Problem

Conventional sheet thickness measuring devices struggle to accurately determine the thickness of individual sheets in a stack due to insufficient contrast and the potential detection of multiple sheets as a single thick sheet, leading to inaccuracies in sheet type identification and printing conditions.

Innovation Solution

A sheet thickness measuring device that illuminates a stack of sheets from a defined area and detects light distribution at a separate area on the side face, using a light shielding member to prevent direct illumination light from entering the detection unit, allowing for accurate calculation of sheet thickness based on propagated light patterns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If only the light reflected by the directly illuminated area of the side face of the sheet stack is captured, then the measurement process is simple, but it is difficult to obtain sufficient contrast to find accurate thicknesses of the respective sheets

Engineering Contradiction:

Improvemeasurement process complexityVSAvoidsheet thickness measurement accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent introduces a light shielding member as an intermediary element that blocks directly reflected light from reaching the light receiving element. This mediator allows only the light that has propagated through the sheets to be detected, thereby achieving sufficient contrast for accurate thickness measurement without significantly complicating the overall measurement process

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If the light reflected from the directly illuminated area is captured, then the device configuration is simple, but the light intensity contrast at gaps between sheets is insufficient leading to lower peaks in light amount

Engineering Contradiction:

Improvedevice configurationVSAvoidlight amount contrast information

Core Design Contradiction:

Device complexityVSLoss of information

Solution Approach 1:

The patent extracts and removes the harmful component (directly reflected light) from the detection process by using a light shielding member. This extraction allows the detection system to capture only the useful information (light that has propagated through the sheets and gaps), thereby preserving the light amount contrast information necessary for identifying gaps between sheets

Inventive Principle:

Principle #2Taking out (Extraction)

3Ease of operation

If conventional optical measurement is used, then manual sheet thickness input is eliminated, but accurate detection of individual sheet thickness is difficult leading to potential detection of multiple sheets as single thick sheet

Engineering Contradiction:

Improveautomatic sheet thickness detectionVSAvoidindividual sheet thickness accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The light shielding member serves as a mediator that filters out directly reflected light, allowing only transmitted light to reach the detector. This enables the system to automatically detect individual sheet thickness with high precision by creating clear peaks in the light amount distribution corresponding to gaps between sheets, thereby solving the problem of misidentifying multiple sheets as a single thick sheet

Inventive Principle:

Principle #24Intermediary (Mediator)

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 enhances the accuracy of sheet thickness measurement by clearly distinguishing peaks corresponding to individual sheets, enabling precise identification of sheet type and optimizing printing conditions.

Implementation Method 1

an illumination unit that outputs a light that is illuminated into a stack of sheets from a first area defined on one of faces including a top face, a bottom face, and side faces of the stack of sheets; a detection unit that detects a light amount distribution of light entered into the stack of sheets and propagated to a second area through the stack of sheets

Methodology Applied

Scientific EffectLight propagation and absorption: Absorption (EM radiation)

Implementation Method 2

a light shield that prevents the light illuminated by the illumination unit from reaching the detection unit without entering into the stack of sheets

Methodology Applied

Scientific EffectLight shielding: Absorption (EM radiation)

Data Source

PatentUS7663769B2Sheet thickness measuring device and image forming apparatus

Publication Date: 2010.02.16 KK TOSHIBA

AI summary

A sheet thickness measuring device includes: an illumination unit that outputs a light that is illuminated into a stack of sheets from a first area defined on one of faces including a top face, a bottom face, and side faces of the stack of sheets; a detection unit that detects a light amount distribution of light entered into the stack of sheets and propagated to a second area through the stack of sheets, the second area defined on one of the side faces of the stack of sheets; and a calculation unit that calculates a thickness of a sheet in the stack of sheets based on the light amount distribution detected by the detection unit.