photoelectric basics

7/31/2019 Photoelectric Basics

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Banner Products


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Early Photoelectric Sensors

Early sensors used anincandescent bulb as

the light source


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Wavelength (nanometers)

400

Ultraviolet Visible Light Infrared

Sunlight

500 600 700 800 900 1000

Red

LEDGreenLEDInfrared

LED

Phototransistor

ResponsePhotocellResponse

BlueLED

Optical Device Response


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Emitter

Receiver

Pulse Modulated Light

A Modulated (Pulsed)Light Source


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onoff

Advantages of LEDs

Long Life

Vibration Resistant

Ability to Modulate

Solid State Reliability


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Photoelectric Keys to Success:

Excess Gain


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Light

on Receiver Element

ReceiversThreshold

Excess Gain (E.G.) =

Excess Gain Formula


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Guidelines ForExcess Gain Values

1.5X

5X

10X

50X

Clean Air

Slightly Dirty

Moderately Dirty

Very Dirty


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Excess Gain Chart


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Photoelectric Keys To Success:

Excess Gain Contrast


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Light Level at Receiver

in Light Condition

Light Level at Receiver

in DarkCondition

Contrast =

Contrast


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1.2 : 1orLess

Unreliable for traditional photoelectrics,consider D12E or D11E

1.2 : 1to

2 : 1

Poor contrast, consider sensors with

ac-coupled amplification

2 : 1

to3 : 1

Low contrast, sensing environment must

remain clean and all other sensingvariables must remain stable

Contrast Values And CorrespondingGuidelines


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Contrast Values And CorrespondingGuidelines

3 : 1to

10 : 1

Good contrast, minor sensing systemvariables will not affect sensingreliability

10 : 1

orGreater

Excellent contrast, sensing shouldremain reliable as long as the sensingsystem has enough excess gain foroperation


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Excess Gain

Contrast

Effective Beam


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Effective Beam OfOpposed Mode Sensors

Receiver

Radiation Pattern

EffectiveBeam

Field-of-View

Emitter


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Effective Beam ForRetroreflective Mode Sensor

Retroreflective

Target

Retroreflective Sensor

Radiation Patternand Field-of-View

Effective Beam


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Effective Beam is the

Sensor Radiation Pattern

Effective Beam

Object

Effective Beam Diffuse Sensing


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Effective BeamConvergent Sensing

Sensing

Depth-of-Field

Area of

Maximum Signal


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Excess Gain

Contrast

Effective Beam

Sensing Modes


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Opposed Mode

Advantages

Most Reliable Sensing Mode

Highest Excess Gain and Longest Range

Great Contrast When Sensing an OpaqueObject

Concerns

May not Work with Transparent or

Translucent Objects


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Emitter

Object

Receiver

Opposed Sensing Mode


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Excess Gain Chart


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Typical Opposed Mode Beam Pattern


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Highest Optical Gain!

Opposed Mode Without Apertures

Proper Alignment

Radiation Pattern

Receiver

Field of View

Effective Beam

Emitter


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Narrow Beam Pattern

Opposed Mode With Apertures

Proper Alignment

Radiation Pattern

Receiver

Field-of-View

EffectiveBeam

Emitter


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Less Tolerant Of Misalignment

Opposed Mode Without Apertures

Misalignment

Radiation Pattern

Receiver

Field of View

Effective Beam

Emitter


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Aperture Examples

WORLD-BEAM


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Improperly Placed

Bottle Cap Breaks Beam

Receiver Emitter

Aperture Application Example

Eff ti B With


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Receiver/Emitterwith Large Lens

Emitter/Receiverwith Small Lens

Emitter/Receiverwith Aperture

Effective Beamis Cone-shaped Receiver/Emitter

with Large Lens

Effective Beam WithUnequal Lens Diameters

Light Ope ate s Da k Ope ate


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Light Operate vs. Dark OperateOpposed Mode System

Light Operate Dark Operate

Output Energized whenBeam is Unblocked, theReceiver Sees Light

Output Energized whenBeam is Blocked, theReceiver Sees Dark


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Retroreflective Mode

Advantages

Good Excess Gain and Range

Great Contrast when Sensing an OpaqueObject

Only Need to Apply Power to One Side

Concerns

Not as Good as Opposed Mode in a Dirty

Environment


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QS18

Retro Target

Object

Retroreflective Sensing Mode


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Retroreflective Sensors with Separate Emitter

and Receiver Lenses Have a Blind Spot at VeryClose Range

Retro Target

Retro Sensor

EmitterLens

ReceiverLens

Target Lens

Retroreflective Blind Spot


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Excess Gain Chart

Typical Beam Pattern


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Typical Beam PatternRetroreflective Sensors


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Extended Retroreflective Range

The Range of Most Retroreflective Sensors may be

Extended by using Additional Retroreflective Target Area

BeamSize

Retroreflective

Sensor

Cluster of BRT-3Retroreflectors


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Boxes with ShinyVinyl Wrap

Retroreflective

Target

RetroreflectiveSensor

Conveyor

Reflected Light

SkewAngle

>10

Use Of Skew Angle To Avoid Proxing


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Polarized Light

Emitted Light isLinearly Polarized

Shiny Object

Retroreflector

Light Reflected 90 byCorner-Cube Reflector willPass thru Receive Filter

Light Reflected in Phase

by Shiny Object andBlocked by Receiver Filter

Retroreflector


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Excess Gain Chart

Light Operate vs Dark Operate


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Light Operate vs. Dark OperateFor A Retroreflective Mode Sensor

Dark Operate

The output is energized whenan object blocks the light from

reaching the retroreflective target.The sensor sees dark

Light Operate

The output is energizedwhen the beam is unblocked,

the sensor sees light

Retro

Target

Opaque

Object

Retro

Target

Retro

Sensor

Opaque

Object


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Move Target Up-Down, Left-Right

Retroreflective Mode Alignment

Retro Target

Up

Down

Left

Right

QS18LV


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Diffuse Sensing Modes


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Diffuse Mode

Advantages

Moderate Excess Gain and Range

Good Contrast

No Need for Power or Reflectoron Opposite Side

Concerns

Contrast and Sensing Distance Depends

on Object Color and Reflectivity


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Object EmittedLight

ReceivedLight

Diffuse Sensing Mode


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Effective Beam

Effective Beam is the

Sensor Radiation Pattern

Object

Effective Beam Diffuse Sensing


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Relative Reflectivity Table

Material Reflectivity (%) Excess Gain Reqd

Kodak white

test card

White paper

Masking tape

Beer foam

Clear plastic

90%

80%

75%

70%

40%

1

1.1

1.2

1.3

2.3


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Black anodized

aluminum

Rough wood pallet

Natural aluminum,

unfinished

Stainless Steel,

micro finish

50%

20%

140%

400%

1.8

4.5

0.6

0.2



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For Materials with Shiny or Glossy Surfaces, theReflectivity Figure Represents the Maximum Light

Return, with the Sensor Beam Exactly Perpendicularto Material Surface


Black neoprene

Black rubber tire

Clear plastic bottle

4%

1.5%

40%

22.5

60

2.3



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Excess Gain Chart

Typical Beam Pattern


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Typical Beam PatternDiffuse Mode Sensors

Diffuse Sensing Of Shiny Surface


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Diffuse Sensing Of Shiny SurfaceSensor Parallel For Reliable Detection

UnreliableReliable

Divergent Proximity


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Divergent ProximitySensing Mode

Object

QS18

Minimum Distance To Reflective Background


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Minimum Distance To Reflective BackgroundSurface For A Diffuse Mode Sensor

3X min.

X

X = Distance From Sensor to Web

3X = Minimum Distance from Web to Floor

Floor

Web Travel

QS18VP6D


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Fixed-FieldSensing Mode


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E

R2

Lenses

Object A Object B

Emitter

Receivers

Sensing Field

R1

Object is Sensed if Amount

of Light at R1 is Greater Than

the Amount of Light at R2

Fixed-Field Sensing Mode


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Fill Level Application

Fixed-Field

Sensor

Filler

Coffee

Can

Direction

Emitter

Receiver


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Light OperateThe output is energized when lightis reflected directly from an objectsurface. The sensor sees light.

Dark OperateThe output is energized when no objectis present in front of the sensor to returnthe emitted light. The sensor sees dark.

ReflectiveObject

For a Proximity Mode Sensor (diffuse, divergent,

convergent, and background suppression)

Light Operate vs Dark Operate

ReflectiveObject


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ConvergentSensing Mode


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Convergent Mode

Advantages

Better Excess Gain and Contrast thanDiffuse Mode Sensing

No Need for Power or Reflector on

Opposite Side Concerns

Limited Range and Sensing Angle is MoreCritical on Shiny Objects


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Convergent Beam Sensing Mode

Sensing

Depth-of-Field

Focus

Object

QS18


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Excess Gain Chart


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Beam Pattern

Convergent Beam


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Bottle Counting

Convergent

Sensor

ProductFlow

QS18


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SM312CV

Direction

Register

Mark

web

Label

ConvergentSpot

NOTE SENSOR

ANGLE

Register MarkDetection


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Fiber Optic Sensing Mode


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Fiber Optic Sensing Mode

Custom Assemblies for Special Mounting

Needs

Hazardous Locations

Moves Light Signal in/out of Remote

Locations Withstands Shock and Vibration

Inherent Noise Immunity

Restricted Sensing Locations Smaller Size than Self-Contained Sensors


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Stainless SteelFerrule (Typical) Stainless SteelInterlock Sheathing

IndividualGlass Strands

PolishedSurface

OpticalEpoxy

Glass Fiber Optic Construction

ki i


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Packing Fraction

IndividualGlass Strand

PackingFraction

~ 30% Signal Loss

Typical IndividualFib O i A bl


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Used for Opposed, Mechanical Convergent,

Specular and Long Range Diffuse Sensing Modes

Fiber Optic Assembly

Typical BifurcatedFib O ti A bl


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Used for Diffuse and Retroreflective Sensing

Two Branches are Randomly Mixed into One

Fiber Optic Assembly

Gl Fib O ti Ad t


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Glass Fiber Optic Advantages

Extreme Temperature Applications -600F,

900 F all Metal Designs

Standard Temperatures -200 F to 480 F,-40 F to 220 F PVC, Phenolic Parts 400 F Maximum

Corrosive/Wet Environments

Profile Matching of Parts Possible

Logic Functions Possible with Multi-Branched Models

Fib O ti C


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Fiber Optic Concerns

System Cost

Loss of Excess Gain

Gl Fib O ti N t


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Glass Fiber Optic Notes

Repeated Flexing Causes Fiber Breakage

Radiation will Darken Glass

Fibers can not be Modified for Length

Pl ti Fib O ti C t ti


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Plastic Fiber Optic Construction

PolishedSurface

Bare

MonofilamentOptical Fiber

Epoxy

DummyInsert

PolyethyleneJacketed

Optical Fiber

Nickel Plated BrassThreaded Tip

Pl ti Fib O ti Ad t


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Plastic Fiber Optic Advantages

Less Cost than Glass Fibers

Flexible-Coiled Models

Less Signal Attenuation than Glass

Field Modifiable Length

Cutters Supplied with Each Cable Assembly

Plastic Fibe Optic Notes


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Plastic Fiber Optic Notes

IR Light not Transmitted well Through Plastic

Visible LEDs are Used

Visible LEDs Have Less Optical Powerthan Infrared LEDs

Single Filament on Relatively Large Scale

Glass .05 mmversusPlastic .25 mm, .50 mm, 1.0 mm,or .1.5 mm

Bend Radius of Cable Affects Transmission


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Application Considerations


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Application Considerations

Environmental

Mechanical

Mode

Interface

Logic

Response Time

Environmental Considerations


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Environmental Considerations

Temperature

Shock & Vibration

Chemicals or Radiation

Electrical Noise

Hazardous Gases, Liquids, Filings

Dirt, Dust, Smoke, Spray, Washdown


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Hazardous Area Sensing

Types Of Sensors For Hazardous Areas


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Types Of Sensors For Hazardous Areas

Explosion Proof

Intrinsically Safe

Namur

NEMA Ratings


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NEMA Ratings

NEMA 4 Hosedown

Stream of water 1 inch in diameter, at a rateof 65 gallons per minute, at a range of 12feet, for a minimum 5 minutes

NEMA 4x Hosedown and Corrosion Same test as NEMA 4, and shall not rust when

subjected to a salt spray (fog) test for 200hours

NEMA Ratings


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NEMA Ratings

NEMA 6 Occasional Submersion

Submerge six feet under water for 30minutes (includes NEMA 4)

NEMA 6P Prolonged Submersion

Submerge Six feet under water for 24hours (includes NEMA 4X)

Mechanical Considerations


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Mechanical Considerations

Size

Angle

Wiring Runs

Accessibility

Indicators

Sensing Mode Considerations


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Sensing Mode Considerations

Opacity of the Target

Effective Beam Size

Range

Contrast

Interfacing Considerations


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Interfacing Considerations

Voltage to Power Sensor

Voltage Required for Load

Current Draw of Load

Response Time of Load

Digital or Analog

Current Sinking Output


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Current Sinking Output

Switching Element

(NPN) Transistor

+V dc

output

dccommon

To+V dc

Todc Common

Load

Current Sourcing Output


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Current Sourcing Output

Switching Element

(PNP) Transistor

+V dc

output

dccommon

Load

To+V dc

Todc Common

Example Of A Solid-StateBipolar Output


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Bipolar Output

+

-

Out

+V dc

dc Common

Current SourcingOutput

Current SinkingOutput

Out

SensingCircuit

Example Of Bi-Modal Output


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Example Of Bi Modal Output

Current Sourcing (PNP) Configuration

SourcingOutputON

Sinking

OutputOFF

36V

Load Output 10-30V dcSupply Voltage

Blue Brown

Current

SenseAndOutputSelect

Load Circuit

Example Of Solid-StateComplementary Output


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Complementary Output

-

NO

+V dc

dc Common

Normally ClosedOutput

Normally OpenOutput

NC

Sensing

Circuit

+

Logic Considerations


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Logic Considerations

L/O or D/O

Single Sensor or Multiple Sensors

Timing Delays or Holds

Response Time of Load

Common Timing Logic


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Common Timing Logic

One-Shot

ON-Delay

OFF-Delay

One-Shot Logic


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One Shot Logic

Signal

Output

ON-Delay Logic


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ON Delay Logic

Delay

Input

Output

OFF-Delay Logic


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OFF Delay Logic

HoldHold

Input

Output

Response Time Considerations


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Response Time Considerations

Width of Part

Linear Velocity

Tr = W/V

Tr = Required Response Time

W = Width of Part

V = Speed of Part

Calculating Response TimeFor Small Objects


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For Small Objects

Width of Object Diameter of Effective Beam

Speed of the Object

Required Response Time

Equals

Application Example


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.55 Inch Diameter Pin

.5 Inch Diameter Effective Beam

Application Example

Emitter Receiver

EffectiveBeam

100"/Sec.

Pin

Application Example


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Application Example

Required Sensor Response Time is Eased

by Use of Apertures

Emitter Receiver

.1" EffectiveBeam

100"/sec.

Pin

Aperture Aperture

Required Sensor Response Time


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Time of Dark Condition

Pin Diameter Effective Beam Diameter

Speed of the Pin through the Beam

Equals

Equals

.55" - .1"100 in./sec.

.45 inch

100 in./sec.4.5 Milliseconds= =

equ ed Se so espo se e


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MeasurementArrays


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Arrays

Scan Analysis Modes


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y

FBB First Beam Blocked

LBB Last Beam Blocked

TBB Total Beams Blocked

CBB Contiguous Beams Blocked

FBM First Beam Made

TBM Last Beam Made

CBM Total Beams Made

ALL All Data

VHSVehicle Separation


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LogProfiling

Hole-In-Web Application


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pp

Edge-Guiding


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g g

Paint Booth ProfilingApplications


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pp


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Laser Photoelectrics

Family


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WORLD-BEAMQS18

WORLD-BEAMQ12

WORLD-BEAM

QS30


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LT7

LT3


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Ultrasonic Sensors

U GAGE T30U


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U-GAGE T30U

Pump-In Application (switch #1 off)


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Sensor

Flow

Pump Control

Initial Level

1 Initial Tank Level Outputs are INACTIVE

11

Low Level (Far Limit)

2 Level Drops Below Far Limit Outputs ACTIVE

2

High Level (Near Limit)

3 Level Rises Above Near Limit Outputs DEACTIVATE

3

1

2

NOTE: If no echo is received by the sensor,the target is assumed to be beyond

the far window limit.

Pump-Out Application (switch #1 on)


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Flow

Pump Control

Sensor

1 Initial Tank Level Outputs are INACTIVE

Initial Level1

2 Level Rises Above Near Limit Outputs ACTIVE

High Level (Near Limit)2

1

3 Level Drops Below Far Limit Outputs DEACTIVATE

Low Level (Far Limit)

2

1

3

NOTE: If no echo is received by the sensor,the target is assumed to be beyond the far

window limit.

QT50U


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QT50U App

lication


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Pallet Load

QT50U Universal Supply VoltageTarget Applications


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Tank Level Detection or Measurement

Q45UR


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Q45UR Has Automatic Windowing


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Follows Same HOLD, CLICK, CLICK,

Routine as other Banner Products

1. Set Window Size with DIP Switches

2. Set up Good Condition

3. Hold, Click, Click to TEACH the

Nominal Good Distance

Good Bad Bad

2 mm

1, 2, 3, or 4 mm Windows

Q45UR And M18


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Web Thickness

M18


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Roll Diameter

S18U Applications


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Minimum and Maximum Limitswith Analog Model to Control

a Clear Object Loop

Retrosonic Sensing Presence ofObjects Regardless of Part Shapeor Orientation


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QS18 Ultrasonic


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photoelectric basics

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