I have no idea how my car’s engine works. Literally, just absolutely no clue. I know gas makes it go. If you think about it, I’m sure there are an endless number of things you use every day that you don’t really understand how they work. We all take these things for granted, which is fine since there are many hard-working people whose jobs it is to fix these things for us if something should go wrong.
But isn’t it nice to be in the know about these things? Not just for your Trivial Pursuit repertoire, though that’s very important, but to know if something goes wrong you’ve got the knowledge to go about fixing it. I know any time I need to have any work done on my car, I call my dad immediately. He knows so much that I don’t, so I want to make sure I’m getting the best deal, and getting what I actually need from my mechanic. When I’m buying a cell phone, though, I go it alone since I’ve got that stuff pretty well figured out. It’s so much easier not having to rely on others to help me with these types of things.
Your scanner is one of those things. The concept of its function in incredibly simple, but the actual execution is pretty complex. As Office Space has shown us, scanners can (and do) stop working, sometimes for seemingly no reason. Equipping yourself with some basic knowledge of how scanners work could end up saving you your time and sanity. So let’s dive in!
The scanner goes through multiple steps between you pressing the scan button and the file showing up on your computer. After your document is placed on the glass plate and you close the cover, that’s when the magic happens. As you probably have noticed, the inside of the cover is most likely white (most are). This makes it so that the background is consistent, making it easier for the scanner to recognize where the document begins and ends. Once you press “scan,” the lamp beneath the glass is used to illuminate your document.
This is where things start to get a little tricky. Scanners use multiple mirrors, a lens, a filter, and a charged coupled device (CCD), which altogether make up the scan head. The scan head is moved slowly across the document by a belt attached to a stepper motor. The scan head is attached to the stabilizer bar to make sure that nothing is moving around when it passes over the document.
When the scan head is moving across the document, the image is reflected through multiple mirrors until finally being reflected through the filter into the CCD. The CCD has light-sensitive photosites arrayed along it that read the level of brightness into electronic signals. These levels of brightness are then processed into a digital image.
Did that make sense? I’ll try and put it in layman’s terms. The light is shot at the paper. The reflection goes through a few mirrors. Then the reflection is shot into the neat light-sensitive board. That reads the level of brightness it’s sensing. A black letter will give off a lower level of brightness than a white blank spot. This is then converted into the digital image we see on our screen. Hopefully the picture helps.
But how does it get there, you ask? Great question. The scan is pretty useless unless we can access it on our computers. Scanners have a few options of how they connect to the computer. A parallel connection, a small computer system interface (SCSI) connection, USB, or FireWire. USB connections are probably the most often used because they’re fast, easy, and affordable.
Other than that, the last piece of the puzzle is to have software that knows how to communicate with your scanner. It’s often referred to as the driver. Think of it as a language barrier. Most scanners speak the same language: TWAIN. Your scanner converted your document into TWAIN. With the help of your software (driver), you’ll be able to turn that TWAIN into readable English on your computer. Though obviously it still works if you’re scanning something in Spanish. I really hope you got that joke. If not, go re-read the entire post and try again.
That’s it! You should feel smarter. I do. Now when something goes wrong with your scanner, you will look like the smartest guy (or girl) in the office. Spew off a few key words and everyone will think you are a genius. You’re welcome. If this doesn’t help you actually fix your scanner in the future, at least you’ll know what the repair guy is talking about.
Imaging Systems Inc 