Barcode scanners are also called barcode readers, barcode scanners, barcode scanners, barcode scanners and barcode readers. They are all the same thing, but they are called differently. It is a reading device used to read the information contained in the barcode. It uses optical principles to decode the content of the barcode and transmit it to the computer or other devices through a data cable or wirelessly.
At present, barcode scanners are connected to computers through wired methods mainly through PS/2 keyboard interface, RS232 serial port, and USB interface. They are connected to computers through wireless methods mainly through Bluetooth and 2.4G. Generally, the wireless distance is basically 30 meters to 100 meters. Barcode scanners are classified into one-dimensional barcode scanners and two-dimensional barcode scanners according to barcodes; they can also be divided into handheld scanners, fixed barcode scanners, and platform barcode scanners. According to the scanning method, barcode scanners can be divided into: CCD barcode scanners, laser handheld scanners, full-angle laser scanners, etc.
The basic working principle of the barcode scanner is: the light emitted by the light source passes through the optical system to illuminate the barcode symbol, and the reflected light passes through the optical system to form an image on the photoelectric converter, which generates an electrical signal. The signal is amplified by the circuit to generate an analog voltage, which is proportional to the light reflected from the barcode symbol. After filtering and shaping, it forms a square wave signal corresponding to the analog signal, which is interpreted by the decoder as a digital signal that can be directly accepted by the computer.
To successfully select a barcode scanner that matches the target requirements, users have three main criteria: working distance, label size and barcode density. The working distance refers to the distance between the scanner and the label during scanning. The scanning distance can range from zero (contact type) to several feet. The scanning distance is determined by the barcode scanner; the label size refers to the entire width of the barcode being scanned; the barcode density refers to the width of the smallest bar or space module that can meet the reading requirements. These three factors are interrelated. For example, the label size and the bar and space modules are larger. Barcodes can also support a larger scanning distance. Light pens, CCD barcode scanners, and laser barcode scanners have different performances, and have different price points and usage cycles. In each aspect, users have to make different considerations.
1. Working distance (depth of field)
The depth of field of the barcode scanner must be clearly defined. When operating, does the operator touch the barcode scanner to the label surface or keep it at a certain distance? Generally speaking, contact or close-range scanning is used in retail, office, and factory applications, while long-range scanning is typically used in warehouse, distribution, and transportation applications.
The depth of field of the three types of barcode scanners is very different. As can be seen from their names, the contact light pen needs to be in contact with the label surface; the working distance of the CCD barcode scanner is limited to 0-30cm, but the latest CCD barcode scanners have effectively extended the depth of field to 60cm; the depth of field of the laser barcode scanner is the longest, between (20-100cm), and some special laser guns designed to scan large barcodes can reach a depth of several feet.
The difference in depth of field can be reflected in the price of the barcode scanner. Whether in terms of cost or life cycle, the light pen is usually the most economical barcode scanner, the laser gun is the most expensive, and the price of the CCD barcode scanner is between the two.
2. Label size/label density
The label density refers to the minimum width of the bar or space unit, measured in one thousandth of an inch, that is, "mil". For linear and one-dimensional barcodes, the size of the label is considered to be the width of the label. High-density barcodes (below 7 mils) need to be scanned at a closer distance, while low-density barcodes (above 15 mils) can be scanned at a longer distance.
When choosing a CCD barcode scanner, be sure to know the full width of the barcode being scanned. In most cases, the maximum width of the barcode that a CCD barcode scanner can scan is limited by the width of the scanner's opening, and some specialized barcode scanners for reading large barcodes need to be specially designed. Since the light produced by the light pen and laser gun can move on the surface of the barcode, both readers can scan relatively wide barcodes.
If you decide to choose a light pen, in terms of hardware, you must consider the aperture of the light pen. The width of the aperture should be roughly equal to the width of the narrowest bar or space of the X-dimensional barcode to be scanned. If the aperture is too large, adjacent barcodes will appear in the scanning window during scanning, making scanning more difficult; if the aperture is too small, the scanner will mistake some printing defects on the barcode for bars or spaces that should not exist in the barcode, causing scanning errors.
3. Image decoding
Once the scanner's beam and recognition system captures the barcode bar or space unit, the information must be converted into symbols that can be recognized by the host computer system. This process is called decoding. The decoding function module can automatically identify the type of barcode being scanned and load the corresponding decoding algorithm to decode the barcode on the label.
The decoded information is formatted as standard RS-232 serial port data, or converted into keyboard commands and transmitted to the host computer system. The decoded information is transmitted to the RS-232 communication interface through a cable, and the keyboard data is transmitted to the keyboard port of the terminal through a "Y" cable. "Interface" is used to represent the technology of connecting the barcode scanner to the host or terminal. The serial port inserts the scanned data into the RS-232 signal between the host or terminal, and the keyboard port treats the data as a string of keyboard signals. Through the programmed software, the barcode scanner can scan the barcode menu to select the parameters of the terminal and interface.
A few years ago, the decoding and communication functions of the barcode scanner needed to be completed by separate devices. The barcode scanner outputs a laser calibration signal (HHLC) or light pen simulation signal to an external decoding box, which completes the decoding and transmission functions. Now, barcode scanner manufacturers have integrated the decoding components of three types of barcode scanners into one part, namely the decoded output scanner (DOS). The decoded output scanner uses a plug-in to provide exactly the same performance as the code box, but at a lower price.
When two or more different types of scanning devices work in their respective decoding states at the same time or require an auxiliary port (for integrated measurement, printing or other I/O devices), an additional decoding port is still required. But from the convenience of integration and low system cost, this integrated decoding scanner is still an excellent choice.
4. Interface device
After the data on the label is decoded, it must be transmitted to the host computer system. The functions of the serial port and keyboard port for formatting data and output have been explained above. Of course, the barcode scanner must be physically connected to the host computer system, so consumers need to determine the type of physical interface of the PC or system. Manufacturers' handheld barcode scanners support hundreds of terminal types and also provide hundreds of interface lines. Users can order appropriate interface lines as needed.
Since the decoded output scanner can support many terminal interfaces with one component, some CCD and laser handheld scanner manufacturers have standardized universal interface line solutions, so that users do not need to reserve a large number of interface lines. Universal interface lines can support both CCD scanners and laser scanners, saving time and money.
The three types of handheld barcode scanners, light pens, CCD scanners and laser scanners, all have excellent performance-price ratios in applications.
Netum has been deeply involved in the field of barcode scanning and document imaging for 15 years, focusing on providing stable, reliable, and technologically advanced data collection solutions for global corporate customers. Our solutions are widely used in retail, logistics warehousing, smart manufacturing, healthcare, government, and public services, effectively improving operational efficiency and data accuracy. We will give you the most professional barcode solution