Principle of dot matrix printer
First, the composition of the dot matrix printer
There are many types and different types of dot matrix printers, which are generally divided into two parts: printing machinery and control and drive circuits. There are three kinds of movements of the pin printer during normal operation, namely the horizontal movement of the print head, the longitudinal movement of the printing paper and the stroke movement of the printing needle. These movements are all controlled by software and driven by some precision machinery.
1. Machinery
The printing mechanical device mainly includes a character car and a transmission mechanism, a printing needle control mechanism, a ribbon drive mechanism, a paper feeding mechanism and a printer status sensor. These mechanisms are precision mechanical devices to ensure that various mechanisms can realize the following various movements.
(1) Character car and transmission mechanism The character car is the carrier of the print head. The print head moves horizontally left and right through the character car transmission system, and then the printing pin hits the ribbon to print the character. The power source of the word car generally uses a stepping motor, and the rotation of the stepping motor is changed into a lateral movement of the word car through a transmission device. Generally, steel wire rope or synchronous toothed belt is used for transmission.
(2) Print pin control mechanism The print pin is the key to correct printing. The printing needle control mechanism realizes the movement of the printing needle withdrawing and withdrawing. Usually use electromagnetic principle to control the movement of the printing pin.
(3) The printing needle of the ribbon drive mechanism hits the ribbon, and the ink on the ribbon prints characters or graphics on the printing paper. During the printing process, when the print head moves to the left and right, the ribbon drive mechanism drives the ribbon to rotate back and forth at the same time, continuously changing the location where the ribbon is hit by the printing needle, ensuring uniform wear of the ribbon, thereby extending the ribbon The service life guarantees the uniform color of the printed characters or graphics.
The ribbon drive mechanism generally uses the word car motor to drive the synchronous toothed belt (such as LQ-1600K) or steel (nylon) wire rope to drive the ribbon shaft to rotate. It can also be driven by two separate motors (such as some color printers) The ribbon is running forward and backward.
(4) Paper feeding mechanism This mechanism realizes the longitudinal movement of the printing paper. After printing a line, it will feed the paper and change the line. Paper feeding methods generally include friction paper feeding, gear feeding, and platen roller feeding. Its power mode is to transform the rotation of the stepping motor into the paper-feeding movement through the traction mechanism.
(5) Printer status sensor For different printers, the sensor settings are different. Usually there are an original position sensor (detecting whether the carriage stops at the original position on the left), a paper end sensor (detecting whether the installed printing paper is used up, and an alarm when it is used up), a timing sensor (detecting the instant position of the carriage) and a machine Cover status sensor (detects abnormal opening of printer cover during printing) and so on.
Control and drive circuit
(1) Control circuit The control circuits of current popular printers have all adopted a microcomputer structure, so the printer is also a complete microcomputer. Divided from the processor category, there are those that use single-chip microcomputer to expand memory and interface circuits, and some that use CPU (to do processor) design. Divided from the composition structure, there is a single CPU structure, there are also master and slave CPU process control structure. Various controls of the printer are performed through software. A bit array font and control program are stored in ROM, and user-defined characters are stored in the line buffer RAM.
(2) Drive circuit The function of the drive circuit is that under the control of the control circuit, the paper feed motor, the carriage motor, and the printing needle are driven out by high voltage.
(3) Interface circuit The printer and host are connected with serial interface, parallel interface and USB interface.
(4) The DC voltage stabilizing circuit provides various DC power supplies for the printer.
Second, the working principle of the dot matrix printer
(I. Overview
The printer itself is a microcomputer system, and the work of the whole machine is controlled by the CPU. Its control program is stored in ROM, so that the CPU can work when it is turned on. The CPU can receive various control commands from the panel, and can also receive commands from the host and interpret and execute various commands. These connections are made through the interface of the computer. In general, there are two working methods for needle punching, Text Mede and Bit Image Print Mode.
1. Text mode
The print data of the pin printer is obtained from the host computer through the interface with the computer. The print data obtained by the printer is the ASCII code of the character to be printed, and these ASCII codes are stored in the print buffer in the printer. After the host computer fills the print buffer each time, the printer sends a "BUSY" signal to the host. After receiving the signal, the host suspends sending the data, and then the printer starts printing.
After printing starts, the CPU in the printer takes out the ASCII code of the printing character from the printing buffer, and calculates the first address of the character dot matrix storage area corresponding to the character. Take out the dot matrix codes of each column one by one according to the address, drive the printing pin, hit the ribbon, and form printing characters on the printing paper. The character generator ROM of the printer usually stores 96 kinds of ASCII codes and font codes of some special characters (some printers also have dot matrix codes of Chinese characters, such as LQ-1600K). When the data in the buffer area is printed, the printer is opened again to receive the new print data from the host computer and start a new printing process.
If it is necessary to print graphics or Chinese characters (for printers without Chinese character library), the pixel signal or Chinese character font code of the graphics can be sent by the host. Obviously, this printing method is similar to the way the display displays characters.
2. Bitmap
In this way, the print data sent by the computer is the data that controls the needle output and withdrawal, so the programmer can directly write a program to control each print pin, so as to print graphics, tables and Chinese characters.
(2) Working principle of the print head
The main part of the pin printer is the print head. Generally speaking, the 9-pin, 16-pin and 24-pin printers refer to the number of print pins on the print head. The print head can be divided into solenoid type, clap type, energy storage type, sound factor type and piezoelectric type according to the needle strike method. Here takes the print head of 24-pin printer LQ-1600K and AR3240 as an example to explain its working principle. The following figure is the working principle diagram of LQ-1600K print head, which is a snap-in print head. In front of each print pin (looking forward from the back of the print pin), there is a ring choke, 12 coils and 12 print pins are arranged around the ring choke (LQ1600K print head is divided into two layers, each layer 12 (Printing needles, 12 in the upper layer are long needles, 12 in the lower layer are short needles), 12 printing needles in each layer are evenly arranged on the circular circumference, and pass through the guide groove on the guide plate at the top of the print head to form two columns Print pins arranged in parallel.
Normally, the printing pin is separated from the driving coil by the elastic force of the return spring. When the driving coil passes current, the armature at the tail of the printing pin is excited to move to the driving coil, and at the same time, the printing pin is driven to hit the ribbon along the multi-layer guide plate, so The belt and printing paper are pressed against the roll. At this time, the ink on the ribbon is penetrated into the printing paper by the impact of the printing needle, leaving a small dot. When the current in the drive coil disappears, the printing pin is reset to its original state by the reset spring, and a printing action is completed. With this snap-on printhead, the printing needle accelerates quickly and the frequency of needle ejection is high. Because the printing needle is divided into two layers, it is more conducive to replacing the printing needle, and the long needle is broken and can be used as a short needle.
At the back of each printing pin (looking forward from the back of the printing pin) there is a ring yoke, around which 24 degaussing coils, 24 armature springs and 24 printing pins are arranged. The 24 printing pins are evenly arranged on the circular circumference, and pass through the guide groove on the guide plate at the top of the print head to form two parallel rows of printing pins.
The working principle of the energy storage print head is to use a permanent magnet to act on the spring, so that the print pin is retracted in the print head in an energy storage state, that is, the print pin stores the impact energy, and when the degaussing coil is energized, it generates a magnetic field with the permanent magnet The magnetic field in the opposite direction reduces the magnetic flux of the permanent magnet and counteracts the attraction of the permanent magnet to the armature and the spring at the rear of the printing pin, so that the spring drives the printing pin to fly forward to complete the throwing action. The advantages of this type of print head are low power consumption and fast printing speed.
Basic knowledge of ribbon
1. The role of the ribbon in the printer
The dot printer uses the dot-matrix striker in the printer head to strike the printing ribbon to produce a printing effect on the printing paper. It can be seen that the ribbon acts as a consumable in this process, and the quality of the ribbon will directly affect the printing effect and even the life of the print head.
Good ribbon = excellent printing effect = long life of the printer
The most important factor that determines the printing effect and service life of the dot matrix printer is the quality of the printing ribbon. High-quality ribbons can generally print more than 3 million characters, while inferior ribbons can only print about 100,000 to 200,000 characters and cannot continue. Normal use, the difference between the two reaches tens of times.
Second, choose a good ribbon
At present, this is the case in China. Imported original ribbons of higher quality are rare in our market. Most of the common ones are imported assembly or domestic ribbons, and there are many which imitate imported original or fake brand names. Fake ribbons are flooding the market.
1. How to identify the quality of the ribbon
Identify the quality of the ribbon of the needle printer mainly from the three aspects of the base, the joint weld and the ink.
1) Ribbon base
Generally speaking, the ribbon base of the ribbon is woven from nylon yarn. Its quality directly affects the service life of the ribbon and the ability of the ink to adhere and penetrate. The bases of printing ribbons currently on the market are divided into nylon 6 and nylon 66. The difference between the two is that the chemical content of nylon is different. Nylon 66 is better than nylon 6 in terms of elasticity, durability, and durability. The well-known brand ribbons on the market generally use nylon 66 as the base. Nylon 66 is divided into four types: low-density, medium-density, high-density, and high-density twisting. The higher the density, the more warp and weft weaves, the better the elasticity; taking 13MM bandwidth and 1CM belt length as an example, high-density belt The warp number is 98-100 woven, the weft number is 44 woven; the high-density twisted belt has a warp number of 105-107 woven, and a weft number of 47 woven. The two can be clearly distinguished when looking at the base of the white belt, but it is not easy to distinguish after dyeing the ink. The warp and weft of the high-density twisted tape are thicker, more durable, and have greater elasticity. The base of the tape for long-term printing is lint-free, continuous thread, and hemp leaf edge. The surface of a good tape base is smooth, without protruding fiber knots, the density of warp and weft is uniform and tight, the cutting edge is straight and uniform, and there is no scorching phenomenon. Touch by hand: The tape base is soft and delicate, with a smooth feeling. Good elasticity and good recovery when pulling. The bad tape base has severe thread breakage, feels hard when touched, the cutting edge is uneven, and the tape edge is scorched. The elasticity is small when pulling, the recovery is poor, and it is often entrained during printing; the base of the tape will be fluffed when it hits 60,000 characters per meter, and the edge of the lotus leaf will be generated, which causes the phenomenon of needle blocking and tape jam. In general, a high-density tape base woven with high-density nylon 66, with a warp and weft density of more than 130 threads per centimeter, and a fiber state with no entanglement, lint, or deformation should be selected. When choosing a ribbon, you can watch the ribbon against the light. If it can't pass the light, it is generally a high-density ribbon base, and the quality is better. If it can pass light, it means that the density of the tape base does not meet the standard requirements. Because of the ribbon woven from this low-density nylon yarn, its print quality will naturally be greatly reduced.
2) Ink
Of course, the ink is also very important. Good ink particles are very small, will not cause clogged pinholes, good fluidity, uniform PH value, strong absorption when coating ink, good moisture retention, durable printing and color transition during printing slow. Good ink is organic, non-toxic, non-corrosive, has no odor, does not become sticky after dyeing, and is easy to dry. Bad ink particles are large, sticky and sticky, and do not dry after dyeing the tape. The tapes produced are strongly adhered. The pinholes are easily blocked during printing, so that the needle cannot be stretched flexibly, which will break the needle.
When choosing, we should know that the ink of the ribbon should be moderate, too much or too little will affect the printing effect. The high-quality ribbon inks are all degreased. When you touch them with your hands, there will be no obvious traces of ink left on your fingers. The printing process of this ink is also very uniform, and there is no obvious difference between the front and back printing effects. And some of the inferior inks we have seen, if they feel greasy when touched by hand, and the fingers are full of traces of ink, it seems that the ink is sufficient, but there will be a phenomenon of heavy color when printing, that is to say, use Touching the paper with your hand will make it blurry. Inferior ink will not only cause poor printing effect, but it can also enter the gap between the print head needles along the print pin guide hole and solidify, clogging the print head, causing the printer to not print normally, and in serious cases, it may cause resistance to the print head. Increase and break the printing pin, the parallel groove of the printing pin is crushed, the print head drive chip or the ribbon motor is burnt out, and other serious failures.
3) Interface
We know that the interface of a good ribbon is flat and narrow, the error is relatively small, the degree of hardening is very light, and the needle is not hanged during printing; the interface is strong and the tensile strength is strong. The bad ribbon interface is wide and long, hard and serious, easy to hang the needle, and the needle is easy to break here.
The basic requirements for the ribbon joint welding seam are as follows: the welding angle should be greater than 30 degrees, the joint at the seam should be smooth, no obvious marks or protrusions, can maintain the original fiber characteristics of the tape base and normal and uniform Absorb ink. The welding seams of high-quality ribbons are all welded by ultrasonic welding machine, which can effectively guarantee the quality of the joint. However, the welding seams welded by simple hot-melt or hot-pressing methods have damaged the fiber characteristics of the tape base to varying degrees, resulting in the welding seam showing a protruding double-layer joint, and the interface is not smooth. This ribbon Often, the printing pin cannot be returned in time, which may cause serious wear, damage or even break the printing pin. Therefore, you should carefully observe the welding seam of the joint when purchasing the ribbon.
Basic knowledge of ribbon usage
We will encounter one or other problems in the process of using ribbons. Here is a summary of everyone's daily use of ribbons.
1. Do it yourself to change the ribbon
In fact, it is not too difficult to replace the printing ribbon by yourself, but the structure of the ribbon holders of different types of pin-type printers are different. Fortunately, the principle of their ribbon operation is similar. We now use Take the commonly used LQ1600 as an example: first, open the upper cover of the printer, you will see a black box shaped like a clip (usually black), we call it a printing frame, and the empty part in the middle is the print head. Remove the printing frame, pay attention to pull up from the end near the print head when disassembling, the printing frame can be easily removed. Then you can open the printing frame, because the structure of the printing frame of different models of printers is different, and its ribbon winding method is slightly different, so you must observe the winding method of the original ribbon, otherwise the ribbon is very likely Can not rotate normally and cause printing failure. It should be noted that the two gears in the print frame must be sandwiched between the colored ribbons, and they should be parallel to them. Otherwise, the ribbons will be displaced with the rotation of the gears, and finally the gears will not be able to rotate. After the ribbon is installed, install the print carriage back to its original position, and the ribbon replacement procedure can be completed.
2. A good way to extend the needle to hit the ribbon
In fact, as just mentioned, ribbons are the main consumables for dot matrix printers, so is there any way we can extend the life of ribbons in daily use? The answer is yes. Now take the AR3200 printer as an example to introduce several methods of saving ribbons. Of course, other printers can be used for reference.
1) Prepare two printing ribbon cassettes, print a formal document with a darker (newly replaced) ribbon, and use a lighter color (used, but the tape base must be intact, otherwise the needle will be damaged ) 'S ribbon prints informal documents or wax paper.
2) Fix two small pieces of foam with transparent tape at the ribbon exit position in the ribbon box, sandwich the ribbon between the two pieces of foam, and at the same time let the foam absorb some good quality printing ink, so as to keep the ribbon wet To extend the usage time of the ribbon.
3) Use two pieces of foam with good quality printing ink to clamp a section of ribbon exposed at the front of the ribbon cartridge, and gently turn the ribbon shaft to add some ribbon to the ribbon that has been used for a while (the tape base is intact) Ink (the entire ribbon must be added, otherwise the color will be different when printing), then open the ribbon box to let the ink ribbon to dry (or add a small amount of gasoline in the ink) to use, first try a few Unofficial pages make the ink evenly distributed. Then print the official draft.
4) Develop the habit of adjusting the distance between the print head and the paper according to the thickness of the paper. The principle is to be bigger, as long as the printing effect meets the requirements. For the new ribbon, the distance can be adjusted appropriately when printing thin paper, because the color is darker, which can ensure the print quality.
5) The ribbon can be removed when printing wax paper. Do not print wax paper directly at this time to prevent wax from melting into the pinhole. Most wax papers are equipped with transparent paper, which can be printed on the wax paper.
6) Sometimes the ribbon of the printing ribbon box is not working, and the printing needle repeatedly prints a certain part of the ribbon, causing the ribbon to have a "hole". At this time, the ribbon box should be opened to check whether the gears and metal cards are in series (large Partly due to too loose card ribbons). For the damaged ribbon, you can cut out the part with holes and then perform "welding". The "welding" method is simple: align and slightly overlap the interface, and stick it with transparent thin tape on the inside (Note: on the inside). Needle (general ribbon only uses the middle section).
According to the quality of the ribbon and the specific situation after printing, the above methods are adopted separately, and the usage time of a ribbon can be extended by as much as 1.5 to 2.5 times, which greatly reduces the consumption of the ribbon.
Ribbon common faults and solutions
When using a dot matrix printer, the most common problem is ribbon failure. Take the EPSON LQ series dot matrix printer as an example to introduce and solve several printer ribbon failures.
1) The ribbon is broken-the tension of the ribbon is too large, breaking the ribbon by breaking the suture or the hammer will cause the ribbon to break. In the former case, the broken part can be cut off and re-stitched; in the latter case, the ribbon can be replaced.
2) The ribbon is jammed-the edges of the ribbon are stripped and fluffed, which easily catches the ribbon wheel, causing the ribbon wheel to get stuck and the ribbon cannot be retracted normally to the ribbon cassette. The solution is: first open the printer cover, open the interlocking handle of the ribbon arm and the hammer row, gently pull the ribbon back at the feeding end of the ribbon cartridge, and then close the ribbon arm and the hammer row interlock Handle, turn on the power, the ribbon will be put back into the ribbon cassette after the machine self-test.
3) The failure of the drive belt of the ribbon drive wheel is worn or broken. This failure is caused by the long use time of the drive belt or the friction of the drive belt with the character chain. The solution is to adjust the position of the character chain so that it no longer rubs the drive belt; if it is broken, please replace it.
3. If the ribbon motion sensing signal is interrupted, first check whether the ribbon motion sensing signal line is damaged. If it breaks, please replace the signal cable; then check whether the ribbon motion sensing signal line at the J6 socket on the interlock conversion board is damaged Or the contact is not good, please replace or plug the signal cable.
Selling point of primary color ribbon
1. Selection of high-quality raw materials
1. Ribbon base
The base of the primary color ribbon is made of high-density nylon 66 imported from Japan. This base has good elasticity and durability. It can print for a long time. The base of the tape is lint-free, continuous, and can not afford the edge of the leaves. The surface of the belt base is flat, without protruding fiber knots, the warp and weft density is uniform and tight, the cutting edge is straight and uniform, and there is no scorching phenomenon.
2. Ink
The ink of the primary color ribbon uses high-quality 708N imported ink. The ink particles are very small, will not cause clogging of the pinholes, the fluidity is very good, the PH value is very uniform, the adsorption is strong when the ink is applied, the moisture retention is good, durable and print The color transition is slow.
Second, the use of excellent welding technology
The primary color ribbon adopts ultrasonic welding technology to effectively ensure the quality of the joint, make the welding interface flat and narrow, the error is relatively small, the degree of hardening is very light, and the needle is not hung when printing; the interface strength is large and the tensile strength is also strong.
Third, the use of advanced ink dyeing process
The primary color ribbon adopts advanced ink dyeing process to make the ink on the ribbon even, moderate and firm.
Fourth, the use of unique outer packaging design
The primary color ribbon breaks through the traditional single outer packaging mode and designs a novel and unique outer packaging, which gives a refreshing feeling.
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