Media Sensor Polarization Filter Brewster Angle Detection

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Solution Overview

Problem

Conventional media sensing systems have low resolution in differentiating among various media types due to overlapping output ranges of diffuse and specular reflectance values.

Innovation Solution

The system employs a media sensor with an optical emitter, a polarization filter, and a detector that emits light at Brewster's angle to polarize reflected light, allowing the polarization filter to filter out specific components, enabling the detector to generate distinct electrical signals for different media types based on refractive indices and surface roughness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional optical detectors are used to detect specular and diffuse reflectance components, then the media sensor can detect media types, but the resolution and ability to differentiate among various media types is low due to overlapping output ranges

Engineering Contradiction:

Improvemedia type differentiation resolutionVSAvoidoptical detection system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

A polarization filter is introduced as an intermediary component between the optical emitter and the optical detector. The filter selectively transmits polarized light while blocking non-polarized light, creating a distinct optical path that enhances the differentiation capability between media types without significantly increasing overall system complexity

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system changes the polarization state parameter of the light by emitting light at Brewster's angle, which polarizes the reflected light. This parameter change creates distinct detection signals for different media types, improving measurement precision while maintaining a relatively simple device structure

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If light is emitted at Brewster's angle to polarize reflected light, then the polarization filter can filter out specific components and improve media type differentiation, but the system requires precise angle control

Engineering Contradiction:

Improvepolarized light filtering accuracyVSAvoidangle of incidence control difficulty

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The optical emitter is pre-positioned at Brewster's angle relative to the print medium surface, establishing the correct angle of incidence before operation begins. This preliminary positioning ensures that the reflected light is properly polarized without requiring continuous angle adjustment during media type detection

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system utilizes the natural polarization properties of light at Brewster's angle to automatically achieve the desired filtering effect. The polarization filter works passively with the naturally polarized reflected light, eliminating the need for complex active angle control mechanisms

Inventive Principle:

Principle #25Self-service

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 ability to distinguish between different media types, improving the resolution and accuracy of media type identification, allowing for precise print instructions and ink usage adjustments.

Implementation Method 1

The optical emitter 106 is positioned and oriented to achieve an angle of incidence of approximately Brewster's angle of the print medium 14. In this way, the print medium 14 polarizes substantially all of the reflected light

Methodology Applied

Scientific EffectBrewster's angle polarization: Brewster's Angle

Implementation Method 2

the print medium 14 polarizes substantially all of the reflected light

Methodology Applied

Scientific EffectLight polarization: Polarisation

Implementation Method 3

The polarization filter 104 is positioned and oriented to receive the reflected light... the polarization filter 104 filters out all of the s-polarized light component

Methodology Applied

Scientific EffectPolarization filtering: Polarisation

Implementation Method 4

the polarization filter 104 filters out all of the s-polarized light component of the reflected light

Methodology Applied

Scientific EffectSelective light absorption: Absorption (EM radiation)

Implementation Method 5

The optical detector 108 detects the filtered light and generates an electrical signal representative of the detected light

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS7780258B2Media sensor with polarization filter

Publication Date: 2010.08.24 AVAGO TECHNOLOGIES INTERNATIONAL SALES PTE LTD

AI summary

An apparatus for sensing a media type of a print medium. Embodiments of the apparatus include an emitter, a polarization filter, and a detector. The emitter is configured to emit light toward a surface of the print medium. The polarization filter is configured to filter polarized light reflected from the surface of the medium. The detector is coupled to the polarization filter and configured to detect the filtered light. The detector is also configured to generate an electrical signal representative of the detected light.