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Anonymous Poster

Sensor type needed

11/20/2007 8:39 PM

Hello, I am in need of a sensor that can operate in an environment with a large amount of UV saturation, I do not believe a regular photo cell will work in this application. It needs to be a transmitted beam type of sensor. Will a class one red visible laser work in this application?

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#1

Re: Sensor type needed

11/21/2007 2:42 AM

I would think so especially if a suitable filter is used over the receiver.

Check on the receiver characteristics / spectrum on manufacturers websites, or get a manufacturers rep' in.

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#2
In reply to #1

Re: Sensor type needed

11/21/2007 4:11 AM

I thought so as well, but I was not sure.....being a holiday weekend I have not been able to get in touch with any manufactuers reps. Thanx for your input

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Anonymous Poster
#3

Re: Sensor type needed

11/22/2007 1:14 AM

i think infrared source is the best choice as its frequency if far a way from uv frequency

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Anonymous Poster
#4

Re: Sensor type needed

11/22/2007 1:57 AM

In Photoelectric sensors, Silicon photodetectors relative response to UV (380nm) is practically zero. Blue LED spectrum (480nm) is about 20%, Green (550nm) 40%, Red (660nm) about 60% and IR (infrared 880~910 nm) is 100%.

So any ThruBeam (opposed emitter -detector), Retroreflective , Diffuse proximity (standard, BGS back ground suppression) would work.

Today the red leds 660nm are ultrabrights (> 4000mcd- millicandelas) most manufacturers use them as they are easier to align and do achieve industrial long ranges thus have become very popular over the past 15 yrs. IRs are now left for specific applications in security (i.e.turnstiles) or ignore color targets, or optical power penetration thru environmetal conditions is needed.

TB: sensing ranges to 12m (for a compact size 31x20x11mm) 20 meters ( larger), 30m to 100m laser types

Diffuse BGS = 2 meters (IR) 1 meter Red LED

Retros= 3 to 30 meters ( Red and IR) Red LED with polirizing filters to detect "silver can type reflections" reliably. Also Transparent sensing models are availables..

check...www.optex-ramco.com

Technical support should be able to guide you to get the best form fit function for your application.

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#5

Re: Sensor type needed

11/22/2007 8:01 AM

You wrote: "I need a sensor that..."

That senses what?

Wangito.

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#7
In reply to #5

Re: Sensor type needed

11/22/2007 12:34 PM

The application is to read kitchen cabinet doors as they travel along a hanging conveyor line in our finishing department. I want to count these doors at they go by a fixed position, the problem is the sensors need to be mounted in a UV oven that dries our topcoat finish. Thanx Steve.....Happy Thanksgiving!!!!!!

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#8
In reply to #7

Re: Sensor type needed

11/22/2007 3:54 PM

A goood filtered IR detector having a narrow beam as a source should do it. or as an alternative 2 to 10 or so GHz microwave source. You can mount the transmitter and receiver outside the oven, if non-metallic cabinet is used, it could be an acceptable UV barrier. there are many µW transmitter/receivers that can be easily modified for the purpose.

And if you can't win them, join them. you could probably measure the UV attenuation or the UV shadow cast by the door while traveling over a UV detector? Just a wild one.

Wangito.

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#9
In reply to #7

Re: Sensor type needed

11/22/2007 5:45 PM

Kitchen cabinet doors; are you counting, monitoring presence, or detecting motion?

What is the sensing range?

What type of output? NPN (sink ) or PNP (source) or Relay

What type of voltage source do you have? (110/220)VAC or DC (10-30volts)

Response time on these sensors is between 500 microseconds and 2 milliseconds

The relays types (VAC) are slower and do not last as long as the digital outputs NPN/ PNP

Depending on your specifications, the list price is about $75 to $95 for the pair, some include mounting brackets

Dont need Infra Red, Visible Red source are much easier to align and you would know if it has power.!!.....UV spectrum (wavelength) does not affect Silicon detectors --is too low to amplify and it is probabbly non-modulated !!!!!!!

If you had issues with heavy contamination you could use ultrasonics- but your application is very common- from your market thru electrical panels, house appliances to automotive!! Photelectrics are used.

Just protect the housings with a bracket type "dog house" so that the UV rays do not attack the housing over time (fade issues). They are "modulated- asynchronous detection" do not pay attention to dc sources like the sun or overhead lamps (60hz and multiples) or your UV lamps

Here are some LED and Laser types.....IP67 and 100G protection!!

Any questions be glad to help!!

Google Photoelectrics Industrial sensors and you will find many other manufacturers

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#11
In reply to #7

Re: Sensor type needed

11/23/2007 6:22 AM

Can't you just use a dichroic UV blocking filter to minimise the amount of UV seen by your sensor? Something like these

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#13
In reply to #7

Re: Sensor type needed

11/23/2007 8:20 PM

why go 'hi-tech' when it will probably become coated with the finish. you have them on an overhead conveyor, install a switch with a whisker to be tripped as they go by. hook the contacts to a counter or your plc program, and it counts for you. if you have your heart set on a sensor use an IR type they are generally good even in high dust areas.

Good luck and have fun,

JJ

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#6

Re: Sensor type needed

11/22/2007 9:57 AM

I am also looking for suitable sensor - to provide online material thickness (steel) data aqusition, any one has suggestion? material thickness from steel coil developed and feeded into rolling milling for cold forming - accuray/precision is looking womewhere equal or better than present micrometer 0.001" (manual check).

thanks

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#10

Re: Sensor type needed

11/22/2007 8:02 PM

What are you trying to sense?

-m-

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#12
In reply to #10

Re: Sensor type needed

11/23/2007 9:05 AM

galv. steel strip gage (thickness).

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