Scan Guard

Discussion in 'FB series of products' started by aricha, Feb 9, 2017.

  1. aricha

    aricha Well-Known Member

    Is there a document about the Scan Guard?
    What is it guarding, the scanners or audience?
  2. Pangolin

    Pangolin Staff Member

    HI Aricha,

    You ask a very good question, and it's one that we really need to clarify in the upcoming FB4 documentation.

    Nevertheless, "Scan Guard" is a kind of scan-fail safeguard that is built into FB4. In order to use it, the FB4 generally must be installed directly inside a laser projector, and must have the "position" signal from the X- and Y-scanners connected to the FB4. When that is done, the FB4 can monitor the position signals and get an idea how fast the scanners are going, and also where the scanners are projecting, and then make intelligent decisions as to whether or not to apply blanking to the signal.

    So, for example, let's say you are projecting a very slow moving beam. This kind of thing is potential harmful for audiences (if the beam is projected directly into an audience, and if the beam has sufficiently high power, and sufficiently low divergence). So "Scan Guard" can be enabled to prevent this sort of thing from happening. There are parameters that you can adjust which control how fast the beam must be moving, and also parameters which will help FB4 to understand where the audience is located (i.e below a "horizon").

    I will STRONGLY CAUTION EVERYBODY that this "Scan Guard" feature SHOULD NOT BE RELIED UPON AS THE SOLE AUDIENCE PROTECTION MEASURE!!! For the absolute best protection, customers should use our PASS system, which is based almost entirely on analog hardware (not software), and which includes multiple redundant circuits to monitor a wide variety of projector behaviors (not just scan speed and position). FB4 "Scan Guard" feature is a good thing to have -- especially as an ADDITIONAL layer of safety.

    Best regards,

    William Benner
  3. aricha

    aricha Well-Known Member