By: Mahnoor Shehzad

Zuha MazharZainab Arif

X-S

Barcode Reader + Scanner 2D/3D

A barcode reader, also called a price scanner or point-of-scale scanner, is an electronic device for reading printed barcodes. Like a flatbed scanner, it consists of a light source, a lens and a light sensor translating optical impulses into electrical ones.

Barcode Reader:

There are five basic types of barcode readers..

- pen wands - slot scanners - charge-couple device (CCD) scanners - image scanner - laser scanners

Types of Barcode Readers:

A pen wand is the simplest barcode reader. It consist of a light source and a photo diode that are placed next to each other in the tip of a pen or wand. To read a bar code, you drag the tip of the pen across all the bars in a steady even motion. The photo diode measures the intensity of the light reflection back from the light source and generates a waveform that is used to measure the widths of the bars and spaces in the bar code.

Dark bars in a barcode absorb light and white spaces reflect light so that the voltage waveform generated by the photo diode is an exact duplicate of a bar and space pattern in the barcode. This wave form is decoded by the scanner in a manner similar to the way Morse code dots and dashes are decoded.

Pen Wand

A slot scanner remains stationary and the item with the bar code on it is pulled by hand through the slot. Slot scanners are typically used to scan barcodes on identification cards.

Slot Scanner

A CCD scanner has a better read-range than the pen wand and is often used in retail sales. Typically, a CCD scanner has a ‘gun’ type interface and has to be held no more than one inch from the bar code. Each time the bar code is scabbed, several readings are taken to reduce the possibility of errors.

A disadvantage of the CCD scanner is that it cannot read a bar code that is wider than its input face.

Charge-Couple Device (CCD) scanners

An image scanner, also called a camera reader, uses a small video camera to capture an image of the bar code and then uses sophisticated digital image processing techniques to decode the bar code. It can read a bar code from about 3 to 9 inches away and generally costs less than a laser scanner.

Image Scanner; barcode reader

A laser scanner, either hand-held or stationary, does not have to be close to the bar code in order to do its job. It uses a system of mirros and lenses to allow the scanner to read the bar code regardless of orientation, and can easily read a bar code up to 24 inches away. To reduce the possibility of error, a laser scanning may perform up to 500 scans per second. Specialized long-range laser scanners are capable of reading a bar code to 30 feet away.

Laser Scanner; barcode reader

There are five basic advantages of barcode readers…

- Speed - Accuracy - Data Integrity - Ease of Implementation - Cost Effectiveness

Advantages of Barcode Readers

- System failure may cost more delays- Scratched or crumpled barcodes may cause

problems- Data must be coded in the barcode- In laser scanning, durability and cost are two

disadvantages.

Disadvantages of Barcode Readers

A scanner is a device that captures images from photographic prints, posters, magazine pages, and similar sources and converts them into digital data for computer editing and display.

2D scanners:

The document is placed on the glass plate and the cover is closed. The inside of the cover in most scanners is flat white, although a few are black. The cover provides a uniform background that the scanner software can use as a reference point for determining the size of the document being scanned. Most flatbed scanners allow the cover to be removed for scanning a bulky object, such as a page in a thick book.

A cold cathode fluorescent lamp (CCFL) is used to illuminate the document. The entire mechanism (mirrors, lens, filter and CCD array) make up the scan head.

The scan head is moved slowly across the document by a belt that is attached to a stepper motor. The scan head is attached to a stabilizer bar to ensure that there is no wobble or deviation in the pass. Pass means that the scan head has completed a single complete scan of the document.

The image of the document is reflected by an angled mirror to another mirror. In some scanners, there are only two mirrors while others use a three mirror approach. Each mirror is slightly curved to focus the image it reflects onto a smaller surface.

The last mirror reflects the image onto a lens. The lens focuses the image through a filter on the CCD array.

Most scanners today use the single pass method. The lens splits the image into three smaller versions of the original. Each smaller version passes through a color filter (red, green & blue) onto a discrete section of the CCD array. The scanner combines the data from the three parts of the CCD array into a single full-color image.

How Scanners Work:

Flat Bed ScannerSheet-fed ScannerHandheld Scanners

Types of 2D Scanners:

These are also called desktop scanners flatbed scanners are the most versatile and popular format. These are capable of capturing color pictures, documents, pages from books and magazines, and, with the right attachments, even scan transparent photographic film.

Advantages: They are widely known for their high quality scans.  They are extremely easy to use, especially for new users.Disadvantages: They’re often large and bulky and tend to take up more

room than other scanners. They are more expensive as compared to other scanners.Use of Application: Offices, Homes

Flat Bed Scanners

These are similar to flatbed scanners except the document is moved and the scan head is immobile. A sheet-fed scanner looks a lot like a small portable printer.

Advantages: Sheet-fed scanners are great for scanning large documents like

manuals or transcripts. A big advantage of a sheet-fed scanner is that it is smaller in size

than a flatbed scanner and uses much less desk space.  They are portable. Good for travelling.Disadvantages: They are not good for scanning images because the document is

actually moving and the scanner itself remains stable. This is the precise reason that these scanners are not very good at scanning any type of graphics. Because the image is zooming past so fast, the scanner must capture a moving target. As a result, the quality and clarity of the image suffers.

Sheet-fed Scanners

These use the same basic technology as a flatbed scanner, but rely on the user to move them instead of a motorized belt. This type of scanner typically does not provide good image quality. However, it can be useful for quickly capturing text.

Advantages:Small (portable) Inexpensive

Disadvantages:Poor quality.You have to manually move it Need to keep your hand steady or else, the image is messed up.

Application of use: Used in warehouses and grocery stores to track inventory, but variations of handheld scanners are used in offices, homes and schools. Some handheld scanners are even made to be taken in a briefcase or suitcase for mobile scanning needs on the go.

Handheld Scanners

A 3D scanner is a device that analyzes a real-world object or environment to collect data on its shape and possibly its appearance (i.e. colour). The collected date can then be used to construct digital three dimension models.

Many different technologies can be used to built these 3D- scanning devices; each technology comes with its own limitations in the kind of objects that can be digitized are still present, for example, optical technologies encounter many difficulties with shiny, mirroring or transparent objects. For example, industrial computed tomography can be used to construct 3D models, applying non-destructive testing.

3D scanners:

Collected 3D data is useful for a wide variety of applications. These devices are used extensively by the entertainment industry in the production of movies and video games. Other common applications of this technology include…

-industrial design -orthotics -prosthetics -reverse engineering -prototyping -quality control

Quickly capture all of the physical measurements of any physical object.

Save time in design work.Ensure parts will fit together on the first try. Capture engineering optimizations inherent in

manufactured parts.Utilize modern manufacturing on parts that we

originally manufacture before CAD Compare ‘a-designed’ model to ‘as-built’ condition of manufactured parts of 3D scanners.

Advantages of 3D scanners:

The size of a 3D scanner can be as big as a small refrigerator

The price of a 3D scanner is expensive. Some small businesses cannot afford them.

Non-contact 3D scanners can be very slow in scanning objects

The clarity of the image may not be the best.

Disadvantages of a 3D Scanner