Optical Sensor External Light Interference Reduction

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Solution Overview

Problem

The existing label detection systems in printing devices are prone to erroneous detection due to external light interference, as the optical sensors are exposed to the atmosphere and cannot accurately distinguish between reflected light from labels and external light sources.

Innovation Solution

A printing apparatus is designed with a reflective optical sensor and a second light receiving portion positioned outside the conveying region to detect external light, allowing for adjustment of the sensor's sensitivity based on the intensity of external light, thereby reducing false detections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the optical sensor is located at a position in the vicinity of the outlet and immediately below the label conveyance path to detect label presence, then the detection position is convenient and responsive, but external light enters the light receiver causing erroneous detection

Engineering Contradiction:

Improvelabel presence detection accuracyVSAvoidexternal light interference

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

A light shielding member is introduced as an intermediary element between the external environment and the light receiver. This member selectively blocks external light from reaching the light receiver while allowing the detection of reflected light from labels, thus resolving the contradiction between detection accuracy and external light interference

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The light receiver area is differentiated into two functional zones: a light reception area that receives reflected light from labels and a light shielding area that blocks external light. This local differentiation allows the sensor to simultaneously achieve accurate label detection while rejecting external light interference

Inventive Principle:

Principle #3Local quality

2Speed

If the light receiver is exposed to atmosphere to receive reflected light from labels, then the optical path is open and responsive, but external light sources interfere with the detection signal

Engineering Contradiction:

Improvedetection response speedVSAvoiddetection reliability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The light shielding member acts as a mediator that preserves the open optical path for label detection while filtering out external light interference, thus maintaining fast response speed while improving detection reliability

Inventive Principle:

Principle #24Intermediary (Mediator)

3Loss of time

If the outlet label-detection sensor is positioned to monitor the conveyance path closely, then detection timing is optimized, but the sensor is exposed to external light causing false presence detection

Engineering Contradiction:

Improvedetection timing accuracyVSAvoidfalse detection signals

Core Design Contradiction:

Loss of timeVSLoss of information

Solution Approach 1:

The light shielding member is positioned to block external light from reaching the light receiver while maintaining the optical path for label detection, thus preserving accurate detection timing while preventing false detection signals caused by external light interference

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

The apparatus effectively minimizes erroneous label detection by adjusting the sensitivity of the optical sensor according to external light conditions, ensuring accurate presence/absence detection of labels despite external light interference.

Implementation Method 1

Light emitted from the light emitter is reflected upon a label, and the reflected light is received at the light receiver

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

The adjustment part is configured to adjust a sensitivity in the detection of the presence of the print medium by the first light receiving portion. Adjustment of the sensitivity of the first light receiving portion is performed based on an intensity of the external light received at the second light receiving portion

Methodology Applied

Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentUS11208230B2Printing apparatus including optical sensor located at conveying region through which label passes

Publication Date: 2021.12.28 BROTHER KOGYO KK

AI summary

A printing apparatus includes a casing, an optical sensor, a second light receiving portion and an adjustment part. The optical sensor includes a light emitting portion and a first light receiving portion. The optical sensor is provided at a position in the vicinity of the outlet and located within a conveying region. The conveying region is an area through which the print medium passes. The second light receiving portion is provided in the vicinity of the optical sensor and positioned outside the conveying region where external light is perceivable. The adjustment part is configured to adjust a sensitivity in the detection of the presence of the print medium by the first light receiving portion. Adjustment of the sensitivity of the first light receiving portion is performed based on an intensity of the external light received at the second light receiving portion.