Optical Sensor Alternating Light for Medium Detection

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Solution Overview

Problem

Scanner devices face erroneous medium detection due to ambient light interference with optical sensors, leading to incorrect determination of medium presence on the conveying path.

Innovation Solution

A medium conveying device with a processor-controlled optical sensor system that alternates light projection between two levels, determining medium presence based on reception light level changes at fixed sampling timings, and positions sensors to minimize ambient light impact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Difficulty of detecting and measuring

If an optical sensor is used to determine medium presence, then detection capability is improved, but measurement precision deteriorates due to ambient light interference

Engineering Contradiction:

Improvedetection capabilityVSAvoidmeasurement precision

Core Design Contradiction:

Difficulty of detecting and measuringVSMeasurement precision

Solution Approach 1:

The projector alternates between first and second projection light amounts at fixed time intervals. The processor determines medium presence by detecting whether the reception light amount alternates correspondingly, enabling distinction between ambient light (constant) and projection light (alternating) signals

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The projection light amount is made dynamic by alternating between two levels, transforming the static optical sensing into a dynamic modulation detection system that can differentiate between static ambient light and dynamic projection light signals

Inventive Principle:

Principle #15Dynamics

2Reliability

If ambient light enters the receiver, then reception light amount increases, but reliability deteriorates due to erroneous determination

Engineering Contradiction:

Improvedetermination accuracyVSAvoidambient light interference

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system converts the harmful ambient light interference into a beneficial reference signal. By comparing the alternating reception light pattern against the known projection light modulation, the system can identify and exclude ambient light components, using them as a baseline for accurate medium presence determination

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

Accurately determines medium presence on the conveying path, reducing errors caused by ambient light and ensuring reliable medium detection and handling.

Implementation Method 1

The optical sensor includes a projector and a receiver. The projector is arranged on the lower surface side and projects light toward the upper surface. The receiver is arranged on the upper surface side to face the projector and receives the light projected from the projector.

Methodology Applied

Scientific EffectLight projection and reception: Light

Implementation Method 2

when a transmissive optical sensor is used for the determination, the light projected from a projector is blocked by the medium to be read, and the medium to be read is determined to be present on the conveying path when the reception light amount of a receiver decreases

Methodology Applied

Scientific EffectLight blocking: Absorption (EM radiation)

Implementation Method 3

when a reflective optical sensor is used for the determination, the light projected from a projector is reflected by the medium to be read, and the medium to be read is determined to be present on the conveying path when the reception light amount of a receiver increases

Methodology Applied

Scientific EffectLight reflection: Reflection

Data Source

PatentUS11765291B2Medium conveying device and determination method

Publication Date: 2023.09.19 PFU LTD

AI summary

In a medium conveying device, a projector projects light, a projection light amount of the light changes, at every fixed time, to a first projection light amount and a second projection light amount less than the first projection light amount, a receiver receives the light projected from the projector, a processor determines, at fixed sampling timings, whether a reception light amount of the receiver is at a first reception light level or a second reception light level smaller than the first reception light level, determines, when the reception light amount alternately changes to the first reception light level and the second reception light level, that a medium is not present on a conveying path, and determines, when the reception light amount is fixed to either the first reception light level or the second reception light level, that the medium is present on the conveying path.