What is a barcode scanner?
Barcode scanner, also known as barcode reader, barcode scanning gun, barcode scanner, barcode scanning gun and barcode reader. It is a reading device used to read the information contained in the barcode. Using the optical principle, the content of the barcode is decoded and transmitted to the computer or other equipment through data line or wireless. It is widely used to scan the barcode of goods and documents in supermarkets, logistics express, libraries and so on.
Structure of barcode reader
The structure of a barcode reader is usually the following parts: optoelectronic device, light source, receiver device, optoelectronic conversion parts, decoding circuit, and computer interface.
There are four main types of photo-sensitive devices used in barcode scanners on the market: photomultiplier tube, silicon oxide isolated CCD, semiconductor isolated CCD, and contact photo-sensitive device (CIS or LIDE).
The mainstream is two CCDs, the principle is simply: in a silicon single crystal integrated with thousands to tens of thousands of phototransistors, these phototransistors are divided into three columns, respectively, with red, green and blue color filter cover, so as to achieve color scanning. Comparison of the two CCDs, silicon oxide isolation CCD and better than the semiconductor isolation CCD, familiar with the physics of friends naturally know the reason. Simply put is the semiconductor CCD transistor leakage phenomenon between the scan accuracy will be affected, with silicon oxide isolation will greatly reduce the leakage phenomenon (this is the insulator), of course, it is best to add temperature control, because whether it is a semiconductor or conductor is generally temperature-sensitive, warming conductivity will generally improve. Now most of the mainstream market is the semiconductor isolation CCD with, silicon oxide isolation CCD is relatively small, apparently because of the higher cost. If you want to understand the effect of a barcode scanner, it is important to understand what quality of optoelectronic components are used in barcode scanners, even if the same semiconductor isolation quality also varies.
Contact photo-sensitive device, it uses a photo-sensitive material is generally the cadmium sulfide we use to manufacture photoresistors, the production cost should be much lower than the CCD (the same precision CIS barcode scanner on the market is always a lot cheaper than the CCD barcode scanner precisely for this reason). The scanning distance is short, the scanning clarity is low and even sometimes does not reach the nominal value, and the temperature change is easy to affect the scanning accuracy, these are exactly the fatal problems of this barcode scanner. Familiar with the physics of friends should know that the cadmium sulfide resistance between the leakage phenomenon than the semiconductor compartment is also large, which also reduces the accuracy.
Photomultiplier tube, the light-sensitive material is mainly metal cesium oxide. His scanning accuracy, even by the degree of temperature and noise, etc. are the best, but also the price is the most expensive. General users such as me are dreaming only, the price is too expensive we skipped its specific technical characteristics here.
A barcode scanner optoelectronic device is an important factor in determining its performance, others such as control circuits, software, etc. are also very important. It can be somewhat difficult to understand this information directly. We often only know a limited amount of content (trade secrets), we can only rely on actual operation and evaluation software to understand when judging the performance of a barcode scanner in the end.
The basic working principle of a barcode reader
The basic working principle of barcode reader is: the light from the light source is irradiated to the barcode symbol through the optical system, and the reflected light is imaged on the photoelectric converter through the optical system to generate an electrical signal, and the signal is amplified by the circuit to generate an analog voltage, which is proportional to the reflected light irradiated to the barcode symbol, and then after filtering and shaping to form a square wave signal corresponding to the analog signal The signal is then filtered and shaped to form a square wave signal corresponding to the analog signal, which is interpreted by the decoder into a digital signal that can be directly accepted by the computer.
The resolution of the barcode scanner
The resolution of the barcode scanner is determined from three aspects: the optical part, the hardware part and the software part. In other words, the resolution of the barcode scanner is equal to the resolution of its optical parts plus its own resolution obtained by processing and analysis through hardware and software.
The optical resolution is the actual number of light points that the optical component of the barcode scanner can capture in each square inch area, which refers to the physical resolution of the CCD (or other photoelectric devices) of the barcode scanner and also the real resolution of the barcode scanner, and its value is the value obtained by dividing the pixel points that can be captured by the photoelectric component by the horizontal maximum sweepable size of the barcode scanner. If the resolution is 1200 DPI, the resolution of the optical part of the barcode scanner often accounts for only 400 to 600 DPI. the resolution of the expanded part is generated jointly by hardware and software, and this process is generated by the computer’s analysis of the image and mathematical filling of the blank part (this process is also called interpolation).
Optical scanning and output are one-to-one, what is scanned is what is output. After the computer hardware and software processing, the output image will become more realistic and the resolution will be higher. Most of the barcode scanners sold in the market now have the function of software and hardware expansion for resolution. Some barcode scanners advertise 9600×9600 DPI, which is only the maximum resolution obtained through software interpolation, not the real optical resolution of the barcode scanner. So for the barcode scanner, its resolution has the optical resolution (or optical resolution) and the maximum resolution, of course we are concerned about the optical resolution, which is the hard work.
When we say that the resolution of a barcode scanner is as high as 4800DPI (this 4800DPI is the sum of optical resolution and software differential processing), it means that when a barcode scanner is used to input an image, 4800×4800 pixels (Pixel) can be collected on a scanning area of 1 square inch. When scanning an image, the higher the scanning resolution is set, the finer the effect of the generated image, and the larger the generated image file, but the more interpolated components.
Classification of barcode scanner
Barcode scanner, also called barcode reader, barcode scanner gun, laser barcode scanner, is widely used in supermarkets, logistics express, libraries, etc. to scan the barcode of goods and documents.
Laser scanner scanning window light transmission mirror using special toughened materials, light transmission rate smooth, depth of field far, the overall plastic needs to be odorless, high temperature resistance, corrosion resistance, easy to scrub, easy to operate the characteristics.
In addition to one, two-dimensional barcode scanner classification. Can also be classified as: CCD, all-angle laser and laser handheld barcode scanners.
Technology used in barcode readers
Ordinary barcode readers usually use the following four technologies: light pen, CCD, laser, and image-based red light.
What is a light pen?
The optical pen is the first handheld contact barcode reader, and it is also the most economical one.
When using, the operator needs to touch the light pen to the surface of the barcode, through the lens of the light pen emits a very small light point, when this light point crosses the barcode from left to right, in the “empty” part, the light will be reflected, and in the “bar” part, the light will be absorbed, so that in the This voltage is amplified, shaped and used for decoding.
Contact with the bar code to read, to be able to clarify which is the bar code being read; reading the length of the bar code can be unlimited; lower cost compared to other readers; no internal moving parts, more robust; small size and light weight. Disadvantages: the use of light pen will be subject to various restrictions, for example, in some occasions is not suitable for contact reading bar codes; in addition, only in a relatively flat surface to read the specified density, print quality bar codes, the light pen can play its role; and the operator needs to be trained to use, such as reading speed, reading angle, and the use of improper pressure will affect its reading performance; finally. Because it must contact reading, when the barcode is damaged due to improper storage, or when there is a protective film on it, the light pen can not be used; the first reading success rate of the light pen is low and the false code rate is high.
What is CCD reader?
CCD is an electronically coupled device, more suitable for close and contact reading, it is not as expensive as laser readers, and there are no internal moving parts.
The CCD reader uses one or more LEDs to emit light that can cover the entire barcode, and the image of the barcode is transmitted to a row of light, which is sampled by each individual photodiode, and the neighboring detection result is “black” or “white” to distinguish each bar or In other words, the CCD reader does not pay attention to read each “bar” or “empty”, but the entire part of the bar code, and converted into an electrical signal that can be decoded.
Advantages: Compared with other readers, the CCD reader is cheaper, but also has a wide range of densities for reading bar codes, easy to use. It is lighter than a laser reader and is not like a light pen only contact reading.
Disadvantages: The limitation of CCD reader is its reading depth of field and reading width, which will be difficult when it needs to read barcodes printed on curved surfaces (such as beverage cans); it is also not very suitable for some occasions that require long-distance reading, such as the warehouse field; CCD has poor anti-drop performance and therefore produces a higher failure rate; CCD is also not a good choice when the barcode to be read is wide, and the information When the barcode to be read is wide, CCD is not a good choice, and the barcode with long information or low density can easily exceed the reading range of the scanning head, resulting in unreadable barcode; Moreover, in some barcode readers with multiple LEDs, the failure of any one of the LEDs will lead to unreadability; Most CCD readers have a low success rate of first reading and a high chance of false code.
What is laser gun?
Laser scanner is a relatively high price among various scanners, but it can provide the highest indicators of various functions, so it is widely used in various industries.
The basic working principle of laser scanner is: a handheld laser scanner sends a beam of light through a laser diode, which is irradiated to a rotating prism or a mirror swinging back and forth, and the reflected light is irradiated to the barcode surface through the reading window, and the light returns to the reader after the reflection of the bar or empty, which is collected and focused by a mirror and converted into an electrical signal through a photoelectric converter, and the signal will be passed through the scanner or the decoding software on the terminal for decoding.
Laser scanner is divided into two forms of handheld and fixed: handheld laser gun connection is convenient and simple, flexible in use, fixed laser scanner is suitable for reading the most larger, smaller bar codes, effectively freeing hands work.
Advantages: laser scanner can be very outstanding for non-contact scanning, usually, in the reading distance of more than 30cm laser reader is the only choice; laser reading bar code density range, and can read irregular bar code surface or through the glass or transparent adhesive paper reading, because of non-contact reading, so will not damage the bar code label; because of more advanced reading and decoding system, the first reading recognition High success rate, faster recognition speed relative to optical pen and CCD, and good recognition of barcodes with poor printing quality or blurred; very low error rate (only about one in three million); good shock and fall resistance of laser readers, such as: SymbolLS4000 series of scanners, which can be 1.5 meters concrete fall resistance.
Disadvantages: The only disadvantage of laser scanner is its relatively high price, but if calculated from the sum of the purchase cost and use cost, there is not much difference with CCD reader.
What is an image-based red barcode reader?
Image type red barcode reader is a barcode reader that can replace laser gun. Its scanning depth of field is up to 30 cm, and with its scanning speed of up to 300 times/sec, it has excellent reading performance. The unique image-based design makes its decoding ability extremely strong, and barcodes that cannot be read by general scanners can still be easily read by Image Red. Through the intelligent interface, the keyboard, RS232 serial port, USB and other interfaces can be converted by simply replacing the cable, and at the same time, it can also be directly connected to a laptop computer. For special devices such as PDAs, some models can be powered directly by built-in batteries, solving the problem of insufficient power supply for PDAs. It can also be set up and software upgraded through software. Its rich data editing functions can make the image type red scanner with the user’s existing software fully compatible. The excellent performance of the image scanner combined with its affordable price will definitely become your best choice.
Types of barcode scanners
There are many types of barcode scanners, etc. The common ones are as follows.
Handheld barcode scanner
Handheld barcode scanner is a product formed by the technology introduced in 1987, the shape is very much like the barcode scanner used by supermarket cashiers holding in their hands. The vast majority of handheld barcode scanners use CIS technology, optical resolution of 200dpi, there are black and white, grayscale, color a variety of types, including color type is generally 18-bit color. There are also individual high-grade products using CCD as a light-sensitive device, which can realize bit true color, and the scanning effect is better.
Small roller type barcode scanner
This is the intermediate product of handheld barcode scanner and platform barcode scanner (there are new ones appearing in these years, because it is built-in power supply and small volume is called notebook barcode scanner) Most of these products use CIS technology, optical resolution is 300 dpi, there are two types of color and grayscale, color type is generally 24-bit color. There are also and a few small roller barcode scanner using CCD technology, scanning effect is significantly better than the CIS technology products, but due to structural constraints, the volume is generally significantly larger than the CIS technology products. The design of the small roller type is to fix the lens of the barcode scanner, and move the object to be scanned through the lens to scan, operating like a printer, the object to be scanned must pass through the machine and then sent out, therefore, the object to be scanned can not be too thick. The biggest advantage of this barcode scanner is that the size is very small, but due to the use of a variety of limitations, such as only scanning thin paper, the range can not exceed the size of the barcode scanner.
Platform Barcode Scanner
Also known as flatbed barcode scanner and desktop barcode scanner, most of the barcode scanners on the market now belong to flatbed barcode scanner, which is the mainstream now. The advantage of flatbed barcode scanner is that it is like using a photocopier, as long as the top cover of the barcode scanner is opened, no matter it is a book, newspaper, magazine or photo negative, it can be put on it and scanned, which is quite convenient, and the scanned effect is also the best among all Common types of barcode scanner in the best.
There are also large format barcode scanners for large format scanning, pen barcode scanners, barcode scanners, negative barcode scanners (note that they are not flat barcode scanners with transverse scanning, the effect is much better, and the price is of course expensive), physical barcode scanners (not flat barcode scanners with physical scanning capability, somewhat similar to digital cameras), and cylinder barcode scanners mainly used in the field of printing and typesetting. Scanners and many others.
Interface types of barcode scanners
The following four types of interfaces are commonly used for barcode scanners.
SCSI (Small Computer Standard Interface)
The maximum number of devices connected to this interface is 8, usually the maximum transmission speed is 40M / S, faster, generally connected to high-speed devices. SCSI device installation is more complex, in the PC generally need to add another SCSI card, easy to generate hardware conflicts, but powerful.
EPP (Enhanced Parallel Interface)
An enhanced bi-directional parallel transmission interface, the maximum transmission speed of 1.5 Mbps. advantage is not required in the PC with other cards, no limit on the number of connections (as long as you have enough ports), the installation of equipment and easy to use. The disadvantage is that the speed is slower than SCSI. This interface is simple and easy to install and use in the low-end of the low performance requirements of the occasion to replace the SCSI interface.
USB (Universal Serial Bus Interface)
Up to 127 peripherals can be connected, the current USB1.1 standard maximum transmission speed of 12Mbps, and a secondary channel for the transmission of low-speed data. In the future, if there is a USB2.0 standard barcode scanner speed may be extended to 480M/s. With hot plug and play function, plug and play. This interface of the barcode scanner with the USB standard in the Intel force to promote the establishment and promotion and gradually popularized.
PS2 (keyboard interface)
And USB usage is similar, need a smart head conversion, generally purchased in the scanner gun will come with the. Now there are still many companies with PS2 interface.
Product features of the barcode scanner
The barcode scanner has the following characteristics.
- (1) scanning window light-transmitting mirror using special toughened materials, more resistant to shattering, light transmission rate more freely, making the depth of field farther;
- (2) gun body plastic in line with national standards production process, so that no odor, high temperature resistance, corrosion resistance, easy to scrub, gun line with a pin can be removed, the operation is very convenient;
- (3) ergonomic design perfect embodiment, beeping sound is bigger (can be small), shock absorption from head to tail reasonably equipped, can resist many times 2 meters fall road ground test.
Application areas of the barcode scanner
Bar code scanner is widely used in commercial POS cash register system, express warehouse logistics, books and garments medicine, banking and insurance communication and many other fields of demand. Keyboard interface, USB interface and RS232 interface three kinds of interfaces are available. The standard product includes the scanner host, USB data cable, manual and white bracket; courier company \ warehousing logistics \ warehouse inventory \ supermarket stores \ books and clothing stores, etc., as long as there is a bar code where there is a laser code existence.
Prospects for the development of barcode scanners
In recent years, the Internet of things as a rapidly developing popular field. There are more and more people in the industry have widely recognized the market prospects of the Internet of Things, although many people feel that the Internet of Things has been deeply rooted in people’s hearts, but there are also many people think that the Internet of Things want to be as short as possible in many areas of universal realization is just an extravagant hope, as the saying goes, see the wisdom of the people, but now according to the familiar Internet of Things is indeed again in some aspects have been very widely used.
Imagine, we are now living in a rapid development of technology, not exaggerate that every day there will be rapid changes, if we now all supermarkets are eliminated with barcode scanner but continue to use the cashier manually enter the number of each item, then the long queue in front of the supermarket checkout counter will bring how annoying shopping experience to everyone. To put it in a small way, people will definitely reduce the queue to go to the supermarket to buy goods, to put it in a larger way, it can directly lead to the decline of consumption level. It is not conducive to the stable development of the economic level. Also, if we go to the mall when shopping for clothes also eliminated the barcode scanner, then the security of the goods will be greatly reduced, and the theft rate will be significantly increased. If we do not have barcode scanner to locate and track the location of the parcel when we shop online, then who can be sure that the goods bought can accurately reach the buyer’s home?
Nowadays, barcode scanning industry technology has been widely used in many fields and industries, such as retail industry, manufacturing, logistics, medical, warehousing, and even security, etc. The most recent craze is the QR code scanning technology on WeChat, which can quickly and accurately screen information. Your phone, with the new version of WeChat (with QR code software) installed, can directly use your phone’s camera to scan and identify the information contained in the QR code. Each WeChat user can generate their own unique QR code, and when you encounter a QR code, your phone can be scanned to accurately appear the information of the person you want to find, which can effectively prevent adding the wrong person as a friend.
Now many fast food restaurants, such as KFC and McDonald’s have taken the lead in using QR code scanning electronic coupons instead of the previous electronic coupons. Because many of the previous electronic coupons had time limits, but the number and location were not limited, leading to a flood of electronic coupons. Now the QR code scanning coupons are no longer limited by time and area, providing convenience to more consumers and a massive promotion for the merchants themselves.
It can be seen that the prospects of barcode scanners will be unlimited, because this is fully in line with the fast-paced pace of modern society people need to do the most convenient thing with the shortest time mentality, and will certainly be the general trend.
China barcode scanner manufacturer www.tractility.com offers PDF417/1D/2D/QR Barcode Scanner/Barcode Reader.