The characteristics of dot matrix printers are: simple structure, mature technology, good performance-price ratio, and low consumption costs. Although dot matrix printers have higher noise, lower resolution, and easy-to-damage printing needles, in recent years, due to the development of technology, the printing speed of dot matrix printers has been greatly improved, the printing noise has been reduced, the printing quality has been improved, and the dot matrix printers have become more popular. Type printers are developing in the direction of specialization and specialization, making them irreplaceable by other types of printers in application fields such as bank book printing, financial invoice printing, continuous printing of recorded scientific data, bar code printing, fast line skip printing and multiple copy production. Function.
Currently, there are two main types of dot matrix printers on the market: 9-pin and 24-pin dot matrix printers. The 9-pin model is not equipped with a Chinese character library. Its basic function is to print letters and numeric symbols. If you want to use it to print simple Chinese characters composed of 16×16 dots, it can only be printed in graphic mode. The printing must be done in two times, that is, the first Print the upper half of a line of Chinese characters with 8 dots at one time, and print the lower half of the Chinese character with 8 dots the second time. The upper and lower parts are combined into a complete line of Chinese characters. Obviously, the speed of printing Chinese characters is very low; if you want to use it to print Chinese characters composed of 24×24 dot matrix, a complete line of Chinese characters will need to be printed at least three times to complete, and the printing speed will be even slower.
According to relevant standards, the definition of "Chinese character dot matrix printer" is: a printer that can print one or more types of printers that meet the international Chinese character glyph dot matrix requirements by printing horizontally once. Currently, the popular 24-pin printers on the market can print Chinese characters composed of 24×24 dots at one time.
The Western dot matrix printer itself does not have a Chinese character library, and the Chinese character library is set on the computer system hard disk. When processing Chinese character information, with the support of the Chinese character operating system (CCDOS), the dot matrix code in the Chinese character library on the hard disk is called according to the Chinese character input code, and the host computer sends the read dot matrix code to the printer in the form of a dot image. For a Chinese character composed of a 24×24 dot matrix, the host must send the corresponding 72-byte dot matrix code to the printer. Obviously, not only the host is busy converting Chinese characters, but also the dot matrix code is continuously transmitted between the host and the printer, which greatly reduces the system efficiency. For printers equipped with their own Chinese character library, when the computer processes Chinese character information, the host only needs to send the Chinese character national standard code (two bytes) that needs to be printed directly to the printer, and the Chinese character national standard code becomes the corresponding dot matrix code. It is completed inside the printer. Compared with the two, the host machine processes a Chinese character and the output of the 72-byte dot matrix code in the past is shortened to the output of the two-byte national standard code, which greatly improves the system work efficiency. The internal hardware and software of the printer can also complete functions such as vertical printing of Chinese characters, horizontal enlargement, vertical enlargement, italic font printing, hollow font printing, reverse white printing, and black font printing. In this way, the functions and printing speed of the Chinese character printer can be fully utilized.
1.1 The basic working principle of dot matrix printers. Dot matrix printers use mechanical and circuit driving principles to make the printing needle hit the ribbon and printing media, thereby printing out a dot matrix, which is then used to form characters or graphics. to complete the printing task. When the printer is online, it receives the print control command, character printing or graphic printing command sent by the PC through the interface. After processing by the printer's CPU, it searches for the first column address of the image encoding corresponding to the character or graphic from the font library. (When printing in the forward direction) or the last column address (when printing in the reverse direction), the codes are found column by column and sent to the print head drive circuit to stimulate the print head to print.
The basic printing steps of a dot matrix printer are: start the character carriage → check whether the print head enters the printing area → perform printing initialization → drive the print head to print a column according to character or graphic encoding → generate column spacing → generate character spacing → After one line of printing is completed, start the paper feeding motor to drive the printing roller and printing paper to feed one line → Line feed (if it is one-way printing, press Enter) to prepare for the next line of printing. This is how the monitoring program controls the printing motor of the dot matrix printer to complete the printing job.
From a structure and principle point of view, dot matrix printers are composed of two parts: "printing mechanical device" and "control drive circuit". There are three types of mechanical movements during the printing process: lateral movement of the print head , the longitudinal movement of the printing paper and the firing pin movement of the printing needle. These movements are performed by software-controlled drive systems through some precision machinery.
The mechanical devices of dot matrix printers include:
(1) Print head driving mechanism (character carriage mechanism)
This mechanism uses stepper motors and gear reduction device, a synchronous toothed belt drives the character carriage to move laterally;
(2) Print head
The print head is the printing mechanism. It is a character-forming component and consists of several printing needles. It is composed of a corresponding number of electromagnets, in which the electromagnet can drive the printing needle to complete the striking action;
(3) Ribbon driving mechanism
One-way is commonly used in dot matrix printers Circulating ribbon mechanism, when the print head moves left and right, the ribbon driving mechanism drives the ribbon to move left, which can change the impact position of the ribbon, ensure uniform wear of the ribbon, extend the service life of the ribbon, and ensure the color depth of the printed characters. consistent. Ribbons are often made of ribbon-shaped nylon or film coated with black or blue ink.
(4) Paper feeding mechanism
The paper feeding mechanism is a mechanism that drives the printing paper to move longitudinally to achieve line feeds.
The paper feeding mechanism of dot matrix printers is generally divided into friction paper feeding and gear paper feeding. The former is suitable for printing paper without paper feeding holes; the latter is suitable for printing paper with paper feeding holes. When the print head completes one line of printing (regardless of the number of characters), the paper feeding mechanism will immediately complete one or more lines of paper;
(5) Printing status sensing mechanism
Different needles The status sensing mechanisms of type printers are different, generally including paper end sensing mechanism, original position sensing mechanism and timing sensing mechanism.
The frame of the dot matrix printer is mainly composed of left and right wall panels, electrical assembly frame and base. The shell is integrally molded by plastic compression and adopts a fully enclosed form to prevent dust and reduce noise.
Modern dot matrix printers also widely use microprocessors, ROM and RAM memories in the control and drive circuits. Among them, the ROM is mainly used to store the management program, character library and Chinese character library of dot matrix printers. The capacity is generally more than 10KB without the Chinese character library, and the capacity is larger after adding the Chinese character library. The RAM is mainly used as a data buffer for the printer to receive host information. One part stores the character set from the ROM after the dot matrix printer is powered on and initialized, and the other part is used for dynamic parameter exchange during program execution. Different dot matrix printers have different RAMs. The RAM of Chinese character dot matrix printers is generally tens of KB, while the RAM of non-Chinese character dot matrix printers is generally only about 1KB. Obviously, modern dot matrix printers can not only complete the control printing task by themselves, but also print Chinese characters independently.
1.2 The main classification of dot matrix printers. On the surface, there is no difference between various types of dot matrix printers. However, with the need for specialization and specialization, different types of dot matrix printers have emerged, among which the main ones are "Universal dot matrix printer", "passbook dot matrix printer", "line dot matrix printer" and "high-speed dot matrix printer", etc. The following will focus on the characteristics, performance and technology of these printers.
⑴Universal dot matrix printer
my country's "universal dot matrix printer" is a very widely used Chinese character printing device in the early days. The number of pins in the print head is generally 24 pins, with wide lines and There are two types of narrow lines. The print head slides back and forth on the metal rod to complete horizontal line printing. The maximum printing width is 33cm, the printing speed is generally 50 Chinese characters/second (standard), the resolution is generally 180dpi, and ribbon printing is used. The paper can be fed by friction and dragging. It can print single pages or print Supplies such as perforated and folded continuous paper, ribbons and print media are inexpensive. Due to electromagnetic impact, the print head will heat up seriously when printing continuously for a long time, but because the printing speed is not fast, the impact will not be big; and because general dot matrix printers are generally wide-format printers and are compatible with DOS systems, they are especially suitable for report processing. Many general offices and financial institutions.
Universal dot matrix printers are easy to use, but if the ribbon and paper are of poor quality or improperly installed, the needles can easily break. When the printed characters are too light, it means that the coloring ability of the ribbon is reduced, and pin hanging and paper blocking are prone to occur. At this time, the ribbon must be replaced. In addition, the ribbons of universal dot matrix printers are not uniform and cannot be substituted for each other. The universal dot matrix printer has a manual adjustment lever to adjust the thickness of the paper. When the thickness of the printing paper changes, be sure to adjust the thickness adjustment lever to adjust the printing depth and protect the printing needle.
⑵ Passbook dot matrix printer
With the development of electronics in various industries, passbook dot matrix printers specially used for counter business in banks, postal and telecommunications, insurance and other service departments have been Rapidly promoted and applied, the so-called passbook dot matrix printer is also called bill dot matrix printer. Compared with other general dot matrix printers, passbook dot matrix printers have the following characteristics:
l Flat push paper feeding: flat push The unique paper path design reduces printing deviations caused by paper bending and paper jams, making it easy for paper to advance and retreat, and also makes it possible to handle ultra-thick printing media;
l Adaptive paper thickness: Passbook dot matrix printer The printing objects are passbooks and other bills, and the thickness of different passbook bills is different, so the passbook dot matrix printer is required to automatically adjust the printing gap and hitting force according to the printing media with different thicknesses to achieve clear printing effects of any thickness;
l Automatic correction technology: It can automatically adjust the printing medium, greatly improving the printing accuracy and making the operator's operation extremely simple;
l Paper positioning technology: In order to make the printing format neat and consistent , install photoelectric sensors on the paper car bracket to automatically detect the left and right boundaries of the paper. Multiple photoelectric sensors are installed at the paper feeding mechanism to detect the top position of the paper to ensure that the paper is absolutely flat relative to the printing bottom plate. Then through the print positioning instructions in the printer control software, the printing position is completely accurate;
l Magnetic stripe reading and writing function: Provides an optional built-in magnetic stripe reader and writer, which can read and write the user's passbook Name, card number, amount and other information, and supports multiple magnetic stripe formats such as ANSI, ISO, NCR, IBM, HITACHI, etc.;
l Printing status identification: It has two-way communication function with the host or terminal, and can The current status and errors that occur are reflected in a timely and accurate manner and handled accordingly. In addition, most passbook dot matrix printers are specially designed to automatically stop printing when the cover is opened, which can prevent printing errors caused by human interference and protect personal safety;
l Other functions: Some high-end passbook dot matrix printers It also provides some optional functions, such as two operators sharing the printer, automatically identifying barcode page numbers, printing magnetic and other cipher text, providing confidentiality and decryption, bank-specific symbol printing, and using Fresh-Rom storage technology to automatically download and upgrade software. wait.
The technical indicators for evaluating passbook dot matrix printers are mainly whether the equipment has good advanced paper processing capabilities, media adaptability range, ease of operation, business processing speed, command simulation capabilities, ease of maintenance and consumables Durability, as well as the scalability of machine functions, etc. In particular, high-end passbook printers should have functions such as automatic paper deflection, automatic edge alignment, and adaptive thickness printing, which can not only ensure highly accurate printing results, but also make the operation extremely easy.
⑶Line dot matrix printer
Line dot matrix printer is a high-end dot matrix printer that can meet the requirements of high-speed batch printing services in banking, securities, telecommunications, taxation and other industries. . Line matrix printers have a strong tendency for professional printing. There are specialized Western character printers and specialized Chinese character printers. Compared with general-purpose dot matrix printers, line dot matrix printers have extremely strong internal data processing capabilities. Due to the complex control of the print head and paper feeding, they generally adopt a master-slave dual CPU processing method, which can greatly increase the printing speed. It can also comprehensively control the printing process.
The print head of a dot matrix printer has a complex structure. In order to ensure that the dot matrix printer does not break due to overheating when printing at high speeds, the heat dissipation and cooling mechanism inside the print head is very good. Line matrix printers have many printing pins and a high pin output frequency. Therefore, the print head also adopts many effective measures and advanced technologies to reduce noise.
The key technology of line matrix printers is the print head, and the needle output frequency is as high as 2000Hz, which is more than twice that of general matrix printers. The number of printing pins is generally 72 pins, 91 pins, 144 pins, and the most is 288 pins, which is more than ten times that of a 24-pin ordinary dot matrix printer. The print head of a line matrix printer adopts a modular structure (for example, a 144-pin print head has 12 modules, each module has 12 pins). Each module only needs to be responsible for horizontal printing for a short printing distance (usually about 1 inch). , much smaller than the printer distance of ordinary dot matrix printers (generally more than ten inches).
The pin arrangement of the printing pin module has a significant impact on the printing speed and performance of the line dot matrix printer. Generally, the line dot matrix printer is divided into straight pin arrangement, oblique pin arrangement and There are several parallel and vertical arrangements.
The straight arrangement method means that the needles in the printing needle module are arranged horizontally and horizontally. When the needle module moves horizontally left and right for printing, it can only complete the printing distance of one line of horizontal dots. The printing height is 1/180 inch or 1/ 144 inches. The speed of a line matrix printer using this arrangement can reach 1,000 lines/minute for Western characters, but the speed for Chinese characters is only more than 200 lines/minute. Therefore, the straight-line dot matrix printer is very suitable for printing output of Western characters.
The oblique arrangement method means that the needles in the printing needle module are arranged diagonally. When the needle module moves horizontally left and right for printing, the module can print several rows of horizontal dots with just a few needles, such as the KD6000C line printer. The module has 12 pins arranged diagonally. The speed of this printer when printing Chinese characters can reach 1000 Chinese characters/minute, which is more suitable for Chinese character output.
The parallel vertical arrangement means that the pins in the printing needle module are arranged in parallel and vertically in two columns. Each module generally has 24 pins. The speed is increased by adding multiple print heads. This is an early Line printing technology has been basically eliminated.
Line matrix printers are high-end printers with a printing pin life of more than 1 billion times/pin, but their life is affected by the quality of the printing paper and ribbon.
⑷High-speed dot matrix printer
High-speed dot matrix printer is a product between ordinary dot matrix printers and line matrix printers. Its main feature is that the printer is very fast. High-speed dot matrix printers are more expensive, but have high printing quality, high printing speed, and can bear heavy printing loads. They occupy an important position in the fields of finance, postal and telecommunications, transportation, and corporate units for batch processing of printing data.
The "patent" of dot matrix printers is the functions of carbon copying and continuous paper feeding. High-speed dot matrix printers also have this capability. At present, the copying capacity of high-speed dot matrix printers is generally 1+4~1+5 layers, and the better ones can reach the copying capacity of 1+8 layers.