A computer scanner is a device which inputs data – a document, a picture, a drawing, or even a three-dimensional object – to the computer system by creating an image of it. It, basically, turns a ‘hard copy’ to a ‘soft copy’.
History of Scanners
A scanner can be considered a related device to facsimile machines and pantelegraph. A pantelegraph is the first form a fax machine, invented by Giovanni Caselli and commercialized in the 1860s. In 1913, Edoard Belin created the Belinograph which uses photocell and allows transmission of images over the phone. Later on, the Belino was introduced in Europe which uses a rotating drum and a photodetector. This rotating drum later on became the focus of improvement and was made to be a drum scanner.
Types of Scanners
Most scanners are used for documents and pictures only. However, some others are used for three dimensional objects:
1. Drum Scanners use photomultiplier tubes (PMT) to capture images. They are called such because they have acrylic cylinders to which reflective originals are mounted. This type of scanner is deemed low quality as the newer scanners use either CCD or CIS.
2. Flatbed Scanners are those which are commonly seen coupled with printers. They each have a glass pane and a light moving under it to scan an image. There are two types of flatbed scanners: The CCD scanner and the CIS scanner. The CCD (Charge-Coupled Device) scanner has a mirror under the light which reflects the document to the CCD. Meanwhile, the CIS (Contact Image Sensor) scanner has no mirror and, as the name implies, needs to be in contact with the image which it needs to scan. The CIS is more portable than the CCD. However, the CIS produces lower quality images than CCDs.
3. Hand held scanners are of two kinds: the Document Scanner and the 3D Scanner. The Document scanner (DS) is used for paper files to be scanned. The Document Scanner is a manual device which requires the user to be steady in dragging it down the document as shaking can distort the image. The DS was popular in the 1990’s and with the recent introduction of flatbed scanners, the DS is, somehow, obsolete. While the DS’ popularity may have waned, hand held 3D (Three Dimensional) Scanners are still popular as they are used in reverse engineering, industrial design, medical application and digital manufacturing. To regulate the shaking of a user’s hand, 3D scanners use reflective tabs, which serve as markers for the device to to align the images properly.
4. Film Scanners are for scanning ‘slides’ (positive) and/or negative films. These are usually small scanners especially designed for camera films. About 4 – 6 slides can be mounted on it at a time. These scanners have the same CCD technology as the flatbeds. However, with the recent development in technology and the introduction of digital cameras, film scanners are rarely used.
Scanner to Computer Connection
Direct Computer Connection – A scanner may be connected directly to the computer with the use of cables specially designed for one end to fit a port in the scanner and the other to fit a port in the computer. The most common ports available in computers nowadays are the USB (Universal Serial Bus) ports which cater to almost all devices, including the scanner. The USB 2.0 quickly transfers data from the scanner to the computer – about 60 megabytes per second.
Indirect Computer Connection – Another way of connecting a scanner to a computer is via network or indirect connection. By connecting a scanner to a network, all the computers connected to the same network can use the aforementioned scanner. This came with the introduction of multi-purpose devices which rolls a fax machine, a scanner and a printer into one.
The regular outputs of scanners are non-compressed images which are stored on the computer. However, it must be noted that some scanners produce a document file – i.e. .doc, .docx and .txt files – of scanned paper files. This makes the document editable and easier to manage.
This device makes storing files easier as they allow files to be made into soft copies that may be stored for a long time. In addition, there are two ways to connect a scanner to a computer – directly and indirectly. The scan output, which generally, is in image format is the data which is stored in the computer and may be reproduced in future time.