Flatbed Scanners
Flatbed Scanners
A standard flatbed scanner
A flatbed scanner is a device that is used to digitise hard copies of documents, converting the paper document into an accurate digital copy. They are the most common form of 2D scanners, with other types including hand scanners and drum scanners, though these are far more rare.
Flatbed scanners are:
- Usually A4 to A3 size
- More accurate than taken a photo because there is no distortion or lighting variation
- Documents are usually digitised to a JPG image of PDF file
Flatbed scanners of use Optical Character Recognition (OCR) software to automatically detect and convert text to an editable form within a PDF file output.
Flatbed Scanners - Video
How Flatbed Scanners Work – video
A video describing how flatbed scanners convert hard copies of documents into a digital copy.
YouTube blocked? Try the Google Drive version.
Flatbed Scanning Process:
- Light is emitted from a light source (usually a xenon tube bulb)
- The light hits the image, altering the intensity and frequency of the light wave, and bounces back.
- Mirrors direct the light towards a lens which folds the light so that it can be concentrated on the Charge Coupled Device
- The CCD cells output an analogue electrical signal, which varies in each cell depending on intensity and frequency
- The electrical signal is passed to an ADC, which converts the signal into a stream of digital data for each portion of the image and sends the data to a buffer
- A stepper motor and belt system moves the scanner head along the full image until the entire image is scanned
- The data in the buffer is converted to a file, such as a PDF or JPG and is transferred to the computer
3D Scanners
3D Scanners
3D scanners are used to make a digital copy of real world physical objects, so that they can be either used with computer software, or so that a physical copy of the original object can be 3D printed. There are lots of different types of 3D scanners, and depending on the type of scanner they might work using:
- Visible light
- Laser light
- Infra red light.
For small objects the object is placed on a turntable and rotated as a light is shone on the object. The distance from the light source is then calculated for each part of the image as it is rotated and this data is used to rebuild the object in it’s digital form.