Triggering An Ir Receiver From A White Object, Capturing 8mm movies

I have started to build a system/circuit to capture old cine 8/super 8 using the Cinecap programme.

I am having trouble to get the IR receiver being triggered when a white blade moves passed the IR receiver.

(There are three blades of which I have painted one white i.e. 2 black blades will pass before the white blade is supposedly required to trigger the system)

For the system I used the following-
A cine projector that can run as slow as 3 frames per second (Eumig 610D).

The moment that the frame "stops" for a split second, you need your camcorder to record the image and these frames are put together by the Cinecap into an AVI file. So when the frame stops, a trigger needs to be activated. In this case an IR receiver is the trigger.
(I also tried with a microswitch, but the capturing was erratic)

My video camera is a 3CCD Panasonic NV GS250

I have done the following: I converted a mouse (acknowledge James Rueben):

http://i261.photobucket.com/albums/ii62/av...led-1copy-2.jpg

Used the following circuit (acknowledge James Rueben)::



Connected to an IR receiver:
OPB608A


http://www.datasheetcatalog.org/datasheets2/22/229105_1.pdf

The IR receiver and all my connections (converted mouse; circuit board) are working well.

My finger, or any white paper triggers a signal which captures a frame via my camcorder on Cinecap, BUT, the paper, my finger, etc need to be very close to the surface of the IR receiver to trigger the signal.

As mentioned before, I painted one of the three blades white, which will hopefully be triggered by the white blade going past.(acknowledge James Rueben):

http://i261.photobucket.com/albums/ii62/av...led-1copy-4.jpg


It only works when I bring the IR receiver very close to the stationary blade.

If the blade rotates at 3fps, it does not trigger a signal, although I bring the receiver quite close.

What is the solution?:

I can see two possibilities
1. Either put something on the blade ? white paper, other material which the IR receiver will pick up (this is where I need advice and this will be the easiest),
2. Or get a stronger?? IR receiver.

I feel that there must be a way to produce a strong input by means of some material to create the trigger. I used PVA paint.

Any advice will be helpful. Will try it out in the next week or two.

Regards
Albie

I need to acknowledge the help I got from James Rueben in this regard- he initiated the project, with the initial input fro Ronypony.
Having Trouble with DIY Telecine (8mm) System - VideoHelp.com

[EDIT]: big pics made links

This post has been edited by Roccivic on May 30, 2009 11:17 pm

now that you have the surface primed with pva ...
try using "silver" (aluminum) paint on the shutter blade .
if that does not work ... time to go to the next level .

http://www.datasheetcatalog.org/datasheets2/31/319115_1.pdf
Gives reflectivity for some surfaces, and distance.
The laser one has more range/sensitivity.
Or you could use a photo interrupter (google) either made from separate LED and photo transistor or as a unit, eg:
http://industrial.panasonic.com/www-cgi/jv...4+ATC7000+5++WW

Thanks for that.

Someone suggested that I use a mirror/foil on the blade. But will try the aluminium paint first

If you have no luck with the IR pickup, you might try a commercial inductive proximity sensor. They make some very small ones, that should fit.

I am learning very fast! Thanks for all the replies.

With regards to pick up, I have had advice as follows;

-Use an IR light or LED light and mount it so that it shines on the white blade
-Either paint the blade aluminum, or use a thin mirror on the blade.

Some felt I should change the R2 value to much higher e.g. 100k resistor.

Any comments so far?

If that doesn't work, I might get a photo interrupter. But as all three blades will be going through the slit, I will need to "extend" the one blade so that only one out of three goes through the slit and triggers the switch. What material would you suggest?

Hopefully something will work, but I need more advice- a very newbie.

tekwiz, please give me mote detail on the "commercial inductive proximity sensor".

Then I might not need to go through all these other options.

Regards
Albie

Info: http://www.ab.com/sensors/products/proximity_sensors/ These sensors are quite small, self contained, & require only a DC supply. Most have output capabilities that will drive most any solid state circuit or even a relay. Googling "inductive proximity sensor" will turn up much more data.
I heve experience with these sensors for industrial automation & they are very accurate & easy to use. Some models offer ±.5mm or better repeatibility. Almost all have built in sensitivity adjustments. They sell for ~$20 each in single quantities.

Thanks for that, but if I use one of these sensors, woudn't it pick up all 3 blades? I need one out of three to be picked up

Yes, the inductive pick-up will pick-up all blades - so you will have to extend one.

If you look at the data sheet for the sensor, there is a chart for normalized collector current vs object distance. That plot tells me that the sensor is designed for operation at very close distances (<0.1 inch). It may be because of the way the internal LED and receiver are oriented.

You can make your own sensor with a narrow beam IR LED and a IR detector. Then position them at appropriate angle and spacing to get optimum performance at the distance from the blade you want. You can also use a Darlington configuration to improve on the current gain of the assembly. Using a mirror film strip will also help.

You can also think about sticking a very small neodymium magnet to one of the blades to change the situation with the inductive sensor. I forgot to ask; is the shutter fan made of metal or plastic? If plastic, you definitely need a magnet. Something like this:

http://www.kjmagnetics.com/products.asp?cat=10

With a magnet, you should be able to use a Hall effect switch as well:

http://www.allegromicro.com/en/Products/De.../an/an27701.pdf

This app. note explains how to increase the effectiveness of the magnets etc. to help with larger gaps.

remember ...
any substantial weight added to one blade of the shutter will cause imbalance .
the same weight (in position) will have to be added to the others to even things up .

I have had replies on other forums as well:

They suggest to increase R2 to 100k and reduce R1 to 68-72 ohm.
Some also feel that the easiest would be to use a photo interrupter.

Any opinions on this?

Regards
Albie

(I havent thought about the weight issue)

This might be the best way. Glueing a tiny plastic flag to one of the vanes would be a way to ensure that only one vane trips the circuit, provided that enough clearance exists within the projector to pass the flag. With properly positioned emitter & sensor, the flag need be no larger than 3mm square. An interrupter setup would certainly offer more positive results than reflective sensing. You can either modify your existing sensor pair, or salvage an interrupter type from an old VCR. They are also sometimes found in old printers or disc drives.

it doesn't take much weight at a fair rpm to cause problems .
that rotary shutter should spin at a good clip .

an interrupter should work well , provided that you can accomplish some things :
an optical path for the shutter blades to run in
trigger from only one blade or use a divide by three counter
eliminate ambient light from triggering the detector side

if you have room you could add small extensions to the shutter blades ; one solid , the others clear plastic ... if they are close in weight it will minimize the imbalance .
ambient light should not be a problem if the detector is mounted on the "dark side" .
that reminds me , which side do you have the ir unit mounted on ?

as for the change in resistor values ... i wouldn't hazard a guess without more information .
an oscilloscope hooked to the detector circuit would help tell the story .
there may not be enough reflectivity differential between the black and "silver" paint at ir wavelengths .

3fps=180RPM. It would take an awful lot of weight to create a serious OOB condition at that speed, especially given the relatively small diameter of the shutter assembly. A few milligrams of plastic flag isn't likely to create any issues.

Thanks for the replies.

The IR was receiver was tried on the "dark" side.

I like the photo interrupter idea with a piece of rigid plastic glued to one blade.

Please have a look at the following site and advise me what you think might work- remember I'm very much a newbie

http://za.rs-online.com/web/search/searchB...1996+4294955625

Thanks!!
Albie

how much room do you have to mount the optointerrupter ?
what type of trigger output do you require ?

a set of good clear pictures showing the area in which the optointerrupter mounts would help in determining the physical requirements . include a ruler for scaling .

I am not at home this week, but will try to take some pictures with a ruler this weekend.

I am not sure what the output should be, but if it helps, the design is such that we basically use the right "click" of the mouse and every "click" triggers the software programme.(see below)

Some more detail I can add:

This is how the set-up should be:

Projector projects to a lens (the Eumig allows for speed to go down with a gear system to 3 fps), produce an ariel image which is captured at 3fps. This is not my set up.




Initially tried a microswitch, but this works erratic, especially at the start of film. The two black wires on the right hand top of the picture of the mouse was used- 5V and 0V.




Cinecap program- screenshot





The photo that I have posted of the IR receiver next to the blade, is not mine. I havent fixed mine, but this is how I painted a blade.

Hope this makes it a bit clearer

This post has been edited by avz10 on June 04, 2009 09:08 pm

hmmm ...

i had some sync and frame issues when converting 8/16mm films with a cine-tele unit .
i got around the issue by using a fast shutter speed on the camera and working the camera closer to the screen .
the increased light level compensated for the fast shutter , this kept the camera from cranking up the ccd/video gain and creating noise .
i was using a sony hi-8 and using the video output to feed the capture device .

Cinecap is supposed to capture every frame with the mouse click and then produces an AVI file. The people who are using the microswitch have reported very good results.

Here are some photos of available space:







From the side:







The in-side of the cover



Hope this gives you an idea of the available space, as I've said before, when I go to buy the resistors, I can just as well buy a photo interrupter

Thanks for any opinions

When you tried the microswitch, where did the actuating motion come from?

Looks like you painted the blade in place (without taking it out). It looks ugly

From the pictures, my guess is that the blade is about 2mm thick. If it rotates true without any side to side play, you can use an interrupter with a slot of 3mm or so. Like:

http://za.rs-online.com/web/search/searchB...oduct&R=1273085

I like the fact that this one has all the signal processing taken care of (Schmitt output). If the blade has a wobble, use a switch with a wider slot. Something like:

http://za.rs-online.com/web/search/searchB...oduct&R=2192533

With this, you will have to do some signal processing or at least add a pull up resistor. Mounting can be done with a spacer on the blade cover itself. However, with that, you will have to estimate various distances accurately and do the final adjustments from front. Or replace the blade cover with a clear acrylic strip that will allow you some view as you adjust the sensor against the blade.

BTW, what currency are the prices in? They seem high numbers.

a micro switch for triggering ? they must have debouncing *somewhere* .
they must use the blade to get a trigger reference for 3 frames , else wise it would miss frames .
do you have enough clearance room on the other side of the shutter blade rotation for extension tabs ?
heh ... removing that shutter blade to paint it would be a royal pain .

in the second picture from the bottom ...
it looks like you have enough room to mount an interrupter .
the clearance between the blade and lens assembly is pretty tight ... not conducive to extension tabs .
i question whether or not a small tab would provide accurate timing for a/the whole blade width .

i am thinking that there must be some way in the software to compensate for the number of shutter blades (etc) ... if there is this will simplify the project over all .
do you have a link to the product with good documentation ?

I will try to give some answers

This projector works on gears- so when you move from 18 fps down to 6 down to 3 fps, the gear changes. That white object at the back is moving with every frame that moves, because the frame is stationary for a split second in the gate. It works very during the film, but, at the beginning of each film there are tensioning issues.

Probably 2mm thick. I thought of attaching rigid plastic, like an old X-ray film and paint that piece black. What other interrupters on the site look ok? and will I be able to use my original circuit then?

Sounds too difficult for me!! Would try the more straight forward ones!

Thought so too, but this is part of the gear system and moves forwards and backwards when you change the projection speed.

The currency is in South African Rand- so divide by 8; so it's only 2 or 3 US dollar

Here is the original link- quite long. The first article is archived, but they give the link later on:

This is the original one that was archived:Read this first

http://web.archive.org/web/*/http://homepa...r8/diytelecine/

The thread:
http://forum.videohelp.com/topic340942.htm...650a674cb469827

Your replies have been excellent. Will buy the resistors next week, and if that doesnt work, will buy an interrupter that I can install with minimum change in my current circuit

Thanks
Albie

When you say it works with a mouse click, I am not sure how the mouse switch is wired inside a mouse. What I mean is, when you click, that switch closure is then translated into a digital signal inside the mouse & sent to the computer. That may be the reason for using a microswitch to keep things simple. Wiring the output of an optosensor to a mouse may or may not work unless you ensure the logic levels are compatible.

If the microswitch works well, there may be another option to keep things simple. Going back to the magnet idea, you could use a reed switch. This being an electromechanical component, will be easy for you to integrate. Reeds are available in various sizes. This one looks OK to me:

http://za.rs-online.com/web/search/searchB...oduct&R=3622518

Don't use the magnet recommended on that page. It is too big and probably meant to slide on the reed (through hole). A small neodymium bar magnet should work. You will have to adjust the spacing. Balance the blades with dummy weights on other segments. Hopefully there is enough clearance all around the blades to mount small magnets? (we can't really see the inside path of the blades). It should be possible to find suitable disc magnets 2 - 3 mm thick.

Colleages, I am wondering if perhaps the original retro reflective sensor might not actually be working, but the problem lies in the output signal being unsuitable for some reason, like too short a pulse, or the wrong level perhaps. Food for thought. Perhaps some method of actually monitoring the output would allow the OP to fine tune the system until it works properly.