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Thread: "60,000 PPS max"?

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    Default "60,000 PPS max"?

    Some scanner sellers mention something like "60,000 PPS max" for their 40,000 point scanners.
    http://www.eightonlight.cn/products/.../0621/120.html

    Is this okay? I can set the speed to 60K in my program, but...

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    No way to tell from the information in that ad. It clearly says 40K ILDA at +-20degrees, though. I'd wonder if that is even true but assuming it is, you can't get to 60K without reducing the angle or allowing the ILDA pattern to distort. Or is 60Khz the maximum frequency response of the amps (I doubt it). Anyway, I'd ignore the 60K since it is probably just marketing BS.

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    I never understood what the "+-20" meant.

    I don't know about this scanner in particular, but I've had luck to test a DT40 and make it run at 60K without reducing the angle (15). The animation I tried actually become more smooth without distortion. I fear that running it at that speed can cause damage though.

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    try that with the ilda12k test pattern (at the risk of breaking your galvos)

    Quote Originally Posted by johnjack View Post
    I never understood what the "+-20" meant.

    I don't know about this scanner in particular, but I've had luck to test a DT40 and make it run at 60K without reducing the angle (15). The animation I tried actually become more smooth without distortion. I fear that running it at that speed can cause damage though.
    suppose you're thinkin' about a plate o' shrimp. Suddenly someone'll say, like, plate, or shrimp, or plate o' shrimp out of the blue, no explanation. No point in lookin' for one, either. It's all part of a cosmic unconciousness.

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    I'll ask Pat Murphy for permission to publish the early three ring binder of the standard. Much will become clear if he allows this.

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    there are a lot of specs (chinese and otherwise) that should written off as marketing hype. sure, you can drive 30k scanners at 40k and depending on the data being projected and the scan angle, it may look excellent, or it may not.

    but... the standard is the Ilda12k test pattern at 30k and 8 degrees. that is the benchmark. the "40k" scanners bill showed in his video did not properly display the test pattern at 40kpps and were having problems displaying it properly at 30k. this does not mean they won't work. it just means they don't meet the advertised spec. as both steve and bill have documented in other posts, the ilda test patterns actually contain data about scanner performance. you can diagnose a lot of scanner issues by watching how the patterns degrade.

    i did get your email. i'll look into it when i'm off work and by my projector.

    we want to assume that when the vendor advertises ilda60k scanners, that's shorthand for "these awesome scanners will display the ilda 12k test pattern properly at 60k pps at at 8 degrees of deflection"... but reality and marketing hype don't intersect on that graph.


    Quote Originally Posted by dream View Post
    Hi Swamidog.
    I've heard alot here myself that running a scanner at a higher speed it is not meant to can damage it.
    But I've also heard from Michal from Moncha that they run 30K scanners at 40K speed with no problem.
    from an email:

    Also I don't remember which chinese companies said this to me, but I've been told I can run a 40K scanner at 60K max if I want to.

    I don't want to question the expertise of many people in this forum, but also the developer of Moncha and the chinese laser projector manufacturers.

    BTW Swamidog, did you get my email?
    suppose you're thinkin' about a plate o' shrimp. Suddenly someone'll say, like, plate, or shrimp, or plate o' shrimp out of the blue, no explanation. No point in lookin' for one, either. It's all part of a cosmic unconciousness.

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    I own a pair of the PT40K, and can confirm that 60K is not within reach if you care about your gear. If pushed that hard, they build up heat really fast while screaming (for mercy) , and the results for graphics are poor for standard factory setting. (Have not fine-tuned them yet). Otherwise, i really like them. Reliable and quite precise if you keep within proper limits of scanningangle and speed.
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    Quote Originally Posted by dream View Post
    I'm not sure why you're telling me all this Swamidog. I wasn't talking about how test patterns will look at 60K with 40K scanners. All I said was I've heard that running a 30K scanner at 40K will damage the scanner and I've also heard people like Michal from Moncha and some chinese companies doing just that. So I don't know what to think.
    How good will the projections look in this case is another topic and I didn't touch that.


    Thanks.
    You can run 30K scanners at 40K at a small fraction of their design scan angle without hurting them. How distorted the image will be is function of the scanner and amplifier design, not the standard. You might get 3-4 degrees of angle at 40 K without serious distortion. You will see it in the image when the image degrades. You will hear the scanner straining next. If you continue to increase the angle and force 40K signals, on most scanners, at some point you may/will do damage. Yet that 3-4 degrees is a small fraction of the scanners full angle range.

    There is NO standard for how much OVERDRIVE a scanner can withstand. Older scan amps had a "coil temperature calculator" circuit to prevent damage. When the Chinese copied the older scanner amps , care to guess which circuit evaporated to save cost? Hint, its the CTC protection circuit. So there is nothing to stop you from applying a signal which may, long term, damage your scanners.

    How do you know what is the bad signal level? You input a standard test pattern and see what happens as you command the image size to increase at a given speed. You will learn what you can push.

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    Quote Originally Posted by swamidog View Post
    the "40k" scanners bill showed in his video did not properly display the test pattern at 40kpps and were having problems displaying it properly at 30k. this does not mean they won't work. it just means they don't meet the advertised spec. as both steve and bill have documented in other posts, the ilda test patterns actually contain data about scanner performance. you can diagnose a lot of scanner issues by watching how the patterns degrade.
    http://www.youtube.com/watch?v=8iWjpz2YEO0

    Quote Originally Posted by dream View Post
    I have a DT40 and they start "screaming" when you try to display something more than 500 points. Setting the kpps in the program to 60K or adding more points doesn't make that sound loader or different. And do we know that the extra heat cause the heat level to reach the safety limit and cause damage?
    it just sounds weird that they say you can run them at 60K while that will destroy them and give a 1-2 year warranty for it. And a it seems weird that a guy like Michal hasn't had a problem yet with running a 30K chinese scanner at 40K speed.

    Don't think that I don't believe you guys when you say running scanners faster than they are meant to run won't damage them. Of course it will. But how fast.
    As Steve said above it's not just speed but angle that matters. Narrow the scan angle and they'll run faster. Whether or not you get a good image is another thing as I believe other factors such as resonance kick in when certain speeds are reached.

    Also most frames are designed to display correctly at 30K. The main reason most people buy faster scanners is so they scan wider. However, the 506's from Pangolin have re-written the rules here as they will go ridiculously wide with very little distortion even though they are 30K. I believe Pangolin claim around 15 degrees for the ILDA test pattern @ 30K compared to around 5 degrees allegedly found for DT40's @30K in their video test (from memory) and for only a little almost unnoticeable distortion, the 506's will go to around 50 degrees at 30K.

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    Quote Originally Posted by dream View Post
    Again, i dont undertsand why you guys are talking about quality. I want to know if running a 30k scanner at 40k or 40k at 60k in your program will actually do any damage, because it seems some noticeable people might have been doing that for a while.
    It depends on what you are displaying. If you are displaying a single dot then you can run them at 1000000000000000000000000 pts per second without any harm. Likewise, simple things like circles where there are no sudden changes in direction can be displayed much more easily than random pts all over the place. My el cheapo Chinese scanners will actually shut themselves off momentarily if they are driven too hard and before that you can visibly see and audibly hear they are having problems. While working on my laser software I have made mistakes and caused my scanners to do things that they should never be asked to do but they are still alive and kicking.

    So, to answer your question, your scanners will let you know if they are OK with 40K or 60K before any damage is done. The scanned images will look like crap and you will back off. I'm sure if you just let them continue to beat themselves up they'd eventually be damaged by only a maniac would do that.

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