Photoelectric General Flashcards
Pros for Opposed Mode
- Reliability (contamination and sensor misalignment from shock and vibration)
- High excess gain
-Impervious to surface reflectivity
-Part Counting
-Aperturing for small parts (if object small, use aperture to make beam smaller)
Cons for Opposed Mode
-Clear Materials
-High Excess Gain at short range
How many types of Retroreflective?
3
Standard
Polarized
Coaxial
Pros for Retroreflect
-Reliable Sensing
-Convenience (only space for one sensor)
Cons for Retroreflect
-Less excess gain (compared to opposed)
-Effective beam (avoid when detecting small objects or for precise positioning control)
-Clear materials
-Shiny materials
- Blind spot at close range
Polarized Retroreflective
- Shorter Range
- Has Blind Spot
Coaxial Retroreflective
- No more blind spot
- Can see clear objects
- Can see through smaller openings
- Precise leading edge detection
Is diffuse light or dark operate
light
Pro for Diffuse
- Convenience (only needs itself)
- Conveyors (Used for straightforward product presence sensing)
Cons for Diffuse
- Dependent on Object Reflectivity and Shape
- Shiny Surface (if angled)
- Background Objects
- Small Parts Detection
- Low Excess Gain
- Count Inaccuracy (bad at counting radiused parts)
Pros for Convergent
- High Excess Gain
- Counting Radiused Objects
- Accurate Positioning
- Fill Level Applications
Cons for Convergent
- Depth of Field
- Effect of Surface Reflectivity
Con for Fixed Field and Adjustable Field
Shiny Surfaces
What are the Environmental Considerations?
Temperature
Moisture
Corrosive
Dirt, Dust, Fog
Vibration and Shock
Electrical Noise
Hazardous Environment
What are the two kinds of Output?
Analog and discrete
What is analog and which applications to use it?
Measurable change in volt or current 0-10 V or 4-20 mA
Applications: Measurements and Inspection
PNP ?
Discrete Sourcing
Volt comes from the brown line (+) to load (-)
NPN?
Discrete Sinking
Volt comes from load (+) to blue line (-)
Pros for Fiber Optics
Tight sensing locations
Vibration and shock
Extreme environment
Explosion proof design
High temps
Custom sensor design
Noise Immunity
Cons of fiber optics
Sensing system cost
Excess gain is low
Applications for fiber optics
Punch press
Vibratory Feeders
Conveyors
Pill counting
Oven
Semiconductor processing equipment
Pros for glass fiber optics
Easy, fast and inexpensive to create glass fiber optic to fit a specific space or sensing environment
Fiber bundle may even be shaped at the sensing end to create a beam to “match” the profile of the object
Most glass fiber optics are very rugged and perform reliably in extreme temps
Cons for glass fiber optics
Breakage of the individual strand resulting from sharp bending or continued flexing as occurs on reciprocating mechanism
Pros for plastic fiber optics
Less expensive and allow less signal attenuation than glass fiber
More flexible and also survive well under repeated flexing
cause of their size, plastic fiber can be routed into extremely tight areas
Cons for plastic fiber optics
Plastic fiber optic require a visible light source for effective sensing
Less tolerant to temp extremes and sensitive to many chemicals and solvents
The bend radius of the cable affects the transmission of light
Pros for Ultrasonic sensors
Immune to light reflection
Pump control
Good for dusty/dirty environment
Chemically resistant models available
Low cost compared to radar
No dead zone if used in retrosonic mode
Cons for Ultrasonic sensors
Windy area
Angled Surfaces
No visible spot
Applications for Ultrasonic Sensors
Tank level and pump control
Web and loop control
Opposed mode for food and beverages
Clear or opaque objects
What is retrosonic sensing?
Not looking for glass bottle but actually looking for other bar of the conveyor belt
What are the add ons for ultrasonic sensors and why
Stilling tubes:
For tank level measurement
Goes all the way into the liquid to calm turbulent surfaces or prevent foam accumulation
Waveguide:
Narrowing the beam
Direct sonic signal through small openings
Mount closer to a tank wall
Eliminate interference from an obstacle
Length should be shorter than dead zone with a 45° chamfer
Applications for T-Gage
Temp sensor
Automotive
Packaging
Material Handling
Baked Goods
Assembly
Why use Radar
Ignore ambient condition
Dust, dirt, wind, fog, rain, sunlight will be able to see through it all
Wide temp range for extreme conditions
Beam angle (can program for region of interest)
FMCW to detect moving and stationary target
FMCW
Frequency Modulated Continuous Wave
Diff between Radar and Ultrasonic?
Radar:
- Detects moving and stationary objects
- Unaffected by wind, rain, snow, fog, and sunlight
- Simple and easy installation
Ultrasonic:
- Susceptible to wind, rain, and snow
- Limited range
- Accuracy in measurement (up to 0.55mm resolution)
Differences between Radar and Laser Sensors
Radar:
- Detects moving and stationary objects
- Unaffected by wind, rain, snow, fog, and sunlight
- Simple and easy installation
- Low/no maintenance
Laser Sensors:
- Affected by rain, snow, fog, dust, and sunlight
- Small detection area
- Laser LED decreases over lifetime
- Accuracy in measurement (up to micron resolution)
How laser work?
Triangulation and Time of Flight (TOF)
Pros for Triangulation for laser?
Shorter range
better resolution
IP69K
Clear Object detection
High precision measurement
Better repeatability than TOF
Applications for Triangulation Lasers
Automotive
Semiconductor
CPG
Food and beverage
Pros for TOF of laser
Longer range
Best in class for range, repeatability and accuracy
High excess gain
Applications for TOF lasers
Overhead Gantry Cranes
Automated Storage
Retrieval
AGV
Automated carts
Repeatability def
Repeatability is the measurement of how reliably a sensor can repeat the same measurement in the same conditions.
Calculated by having a sensor detect a motionless single color target multiple times in a lab setting
Resolution Def
Resolution of a sensor tells you the smallest change in distance that the sensor can detect
Resolution can be impacted by target conditions: Distance to the target sensor, response speed, and other factors
Linearity Def
Linearity is the maximum deviation between an ideal straight line measurement and the actual measurement. It indicates how closely a sensor is, analog output can approximate a straight line when measuring across the sensor range
Accuracy Def
Accuracy is the difference between the actual distance to a target and the sensor measure distance and is important when using the measurements direct from sensor VIA IO-Link
What is an amplifier for fiber optic
It puts the emitter and receiver together
