欧美亚洲h动漫一区二区_观看黄色网站_国产 日韩 欧美 综合_国产精品色午夜视频免费看,亚洲精品第一国产综合精品,美女1314视频在线观看,饥渴老熟妇女人乱伦视频















    





 



    

    

    2D barcode technology


    

    

    Time：


    
2023-05-08



    

    One-dimensional barcodes only express information in one direction (generally horizontal), while in the vertical direction do not express any information, and their certain height is usually to facilitate the alignment of the reader. The application of 1D barcodes can improve the speed of information entry and reduce the error rate, but 1D barcodes also have some shortcomings: * Small data capacity:




    
One-dimensional barcodes only express information in one direction (generally horizontal), while in the vertical direction do not express any information, and their certain height is usually to facilitate the alignment of the reader. The application of 1D barcodes can improve the speed of information entry and reduce the error rate, but 1D barcodes also have some shortcomings: * Small data capacity:



about 30 characters * Can only contain letters and numbers * Barcode size is relatively large (low space utilization)





* Barcode cannot be read

after it is damaged A barcode that stores information in a two-dimensional space horizontally and vertically is called a 2-dimensional bar code.

Like 1D barcodes, 2D barcodes have many different encoding methods, or symbolic systems. In terms of the coding principles of these symbolic systems, they can generally be divided into the following three types

: 1. Linear stacked QR code is generated by stacking multiple one-dimensional codes vertically on the basis of the principle of one-dimensional barcode coding. Typical symbology such as: Code 16K, Code 49, PDF417, etc.

2. Matrix QR code is encoded in a rectangular space through the different distributions of black and white pixels in the matrix. Typical symbology such as: Aztec, Maxi Code, QR Code, Data Matrix, etc.

3. Postal code is encoded by strips of different lengths, mainly used for mail encoding, such as: Postnet, BPO 4-State.

Among the many types of two-dimensional barcodes, the commonly used symbologies are: Data Matrix, Maxi Code, Aztec, QR Code, Vericode, PDF417, Ultracode, Code 49, Code 16K, etc., among which:

* Data Matrix is mainly used for the identification of small parts in the electronics industry, For example, Intel's Pentium processor has this code printed on the back.

* Maxi Code was developed by United Parcel Service (UPS) for package sorting and tracking.

* Aztec was introduced by Welch Allyn and can hold up to 3832 numbers or 3067 alphabetic characters or 1914 bytes of data.



Below, we take the PDF417 code as an example to introduce the characteristics and characteristics of the two-dimensional barcode.



a) Introduction

to PDF417 The PDF417 code was invented by Dr. Wang Yinjing, a Chinese in the United States. PDF is an abbreviation of the first three words of Portable Data File, which means "portable data file". Because each symbol character that makes up the barcode is composed of 4 bars and 4 blanks, if the narrow bar or empty bar that makes up the barcode is called a module, the total number of modules of the above 4 bars and 4 empty must be 17, so it is called 417 code or PDF417 code.



2) Features of PDF417

1. Large information capacity PDF417 code can express binary numbers in addition to letters, numbers, and ASCII characters. In order to make the encoding more compact and improve the information density, PDF417 has three formats when encoding:

* Extended alphanumeric compression format can hold 1850 characters;

* Binary / ASCII format can hold 1108 bytes;

* Number compression format can hold 2710 numbers.

2. Error correction ability 1D barcodes usually have a verification function to prevent misreading, and will be rejected if the barcode is defaced. And two-dimensional barcodes not only prevent errors, but also correct them, restoring the correct information even if the barcode is partially damaged.

3. The printing requirements are not high Ordinary printing equipment can be printed, and fax copies can also be read.

4. Can be read with a variety of reading devices The PDF417 code can be read with a laser reader with a grating, a linear and surface scanning image reader.

5. Can the size be adjusted to fit different print spaces?

6. The disclosure of the code system has become an international standard, and China has also formulated a national standard of 417 codes.



3) The error correction function of PDF417 The

error correction function of the two-dimensional barcode is realized by repeatedly representing part of the information (redundancy). For example, in the PDF417 code, a certain line contains information in addition to the bank's information, and there is some information that reflects characters in other positions (error correction codes). In this way, even if a part of the barcode is damaged, it can be restored by correcting the code that exists elsewhere.

PDF417 error correction ability according to the number of error correction code words is divided into 0 ~ 8 a total of 9, see Figure 4, don't the higher, the more correction code words, the stronger the correction ability, the larger the barcode. When the correction is 8, even if the barcode is 50% defaced, it can be read correctly, as shown in Figure 5.



4) Several variations of PDF417

As shown in Figure 6, PDF417 also has several variant symbolic forms:

* PDF417 truncated code In a relatively "clean" environment, where the possibility of barcode damage is small, the line indicator on the right can be omitted and the terminator reduced.

* PDF417 Microcode Further reduced PDF code.

* Macro PDF417 code When the file content is too long to be represented by a PDF417 code, it can be represented by a macro PDF417 code containing multiple (1~99999) barcode blocks. The advantages of two-dimensional barcodes

From the above introduction, it can be seen that two-dimensional barcodes have obvious advantages compared with one-dimensional barcodes, which can be summarized in the following aspects:

1) Larger data capacity The PDF417 code in the

figure contains all the text in the text box.

2) Beyond the limitations

of alphanumeric 3) The relative size of the barcode is small

4 ) It has the ability



to resist damage The application of two-dimensional barcode

I) Application of the transportation industry

A typical transportation business process usually goes through: suppliers - > freight forwarders, freight forwarders - > freight companies, freight companies - > customers and other processes, each process involves the processing of delivery documents. The shipping document contains a large amount of information, including: consignor information, consignee information, cargo list, mode of transportation, and so on. The premise of document processing is data entry, and the manual keyboard input method has the problem of low efficiency and high error rate, which can no longer meet the requirements of the modern transportation industry. Two-dimensional barcode provides a good solution in this regard, the content of the document is compiled into a two-dimensional barcode, printed on the shipping document, in all aspects of the transportation business using the two-dimensional barcode reader to scan the barcode, the information is entered into the computer management system, both fast and accurate.

In the U.S., while EDI applications have revolutionized the core of business processes, they have unfortunately ignored a key player in the process—the trucking company. Many EDI messages are always late for shippers, so much so that the shipment and customer document generation is affected by the inability to confirm accurate shipment note information in a timely manner. The American Trucking Association (ATA) therefore proposed a paper-based EDI system. The sender compiles the EDI information into a PDF417 barcode label and submits it to the shipper, and by scanning the barcode, the information is immediately transmitted to the shipper's computer system. All this happens at the right time and at the right place, making the entire transportation process much more efficient.

ii) Application of Identification Cards The

U.S. Department of Defense has printed PDF417 codes on military identification cards. The cardholder's name, rank, photo and other personal information are compiled into a PDF417 code printed on the card. Cards are used for access control of important places and hospital visits. The advantages of this application are real-time data collection, low implementation costs, the ability to read damaged cards (such as gunshots), and counterfeit protection.

The resident identity card of the Hong Kong Special Administrative Region of China has also adopted the PDF 417 code. Other applications such as business licenses, drivingLicenses, passports, temporary residence permits

for floating populations in China's cities, and medical insurance cards are also good application directions.

iii) Documents and Forms Application Every broker

of Seimei Insurance Company Japan carries a laptop when meeting clients. Each policy and agreement is created and printed out in a computer.

When they return to the office, they need to manually enter the policy data into the company's host.

In order to improve the accuracy and speed of data entry, they compiled the policy content into a PDF417 barcode and printed it on the document at the same time as the policy, so that

they could use a two-dimensional barcode reader to scan the barcode and enter the data into the host.

Other similar applications include: customs declarations, tax returns, various application forms from government departments, etc.

4) Asset Tracking

American steel pipe companies have different kinds of pipes in various places that need to be maintained. To track each tube, they compile the tube number, position number, manufacturer, length, etc., size, thickness and other information into a PDF417 barcode, make a label and attach it to the tube. When the tube is removed or installed, the operator scans the barcode label and the database information is updated in a timely manner. Factories can use two-dimensional barcodes to track production equipment; Hospitals and clinics can also use 2D barcode labels to track devices, computers, and surgical instruments.