What is the principle of a dot matrix printer and how does it make the corresponding needles protrud

The main component of a dot matrix printer is the print head, and the 9-needle, 16-needle, and 24-needle printers usually refer to the number of print needles on the print head. According to the firing method, the print head can be divided into solenoid type, pat type, energy storage type, sound factor type and piezoelectric type. Here we take the printhead of the 24-pin printer LQ-1600K and AIZ3240 as an example to illustrate its working principle.

The picture on the right is the working principle diagram of the LQ-1600K print head, which is a snap print head. In front of each printing needle (looking forward from the back of the printing needle), there is a circular choke, and 12 coils and 12 printing pins are arranged around the circumferential choke (the LQ1600K print head is divided into two layers, each layer has 12 printing needles, the upper layer is 12 long needles, and the lower layer is 12 short needles), and the 12 printing needles in each layer are evenly arranged on the circumference of the ring, and penetrate out at the top of the print head along the guide groove on the guide plate to form two parallel rows of printing needles.

As can be seen from the figure, usually the printing pin is in the state of leaving the driving coil by the elastic force of the return spring, when the driving coil passes the current, the armature at the end of the printing needle is excited to move to the driving coil, and at the same time, the printing needle is driven to hit the ribbon along the multi-layer guide plate, so that the ribbon and the printing paper are pressed to the scroll. At this point, the ink on the ribbon is struck by the print needle and penetrates into the paper, leaving a small dot. When the current in the drive coil disappears, the print pin is returned to the original state by the return spring to complete a printing action.

This kind of pat type print head, the printing needle accelerates quickly, the frequency of the needle is high, because the printing needle is divided into two layers, it is more conducive to replacing the printing needle, and the long needle can be used as a short needle when it is broken.

Diagram of the working principle of the AR3240 printhead.

The picture on the left is the working principle diagram of the AR3240 printhead, which is an energy storage printhead. Behind each stin (looking from the back of the stitch forward) there is a circular choke around which 24 degaussing coils, 24 armature pins, and 24 pins are arranged. The 24 pins are arranged evenly around the circumference of the ring and threaded at the top of the print head along the guide groove on the deflector plate to form two parallel rows of pins.

As can be seen from the figure, the working principle of the energy storage print head is to act on the spring with a permanent magnet, so that the printing needle is shrunk in the print head in the energy storage state, that is, the printing needle stores the striking energy, and when the degaussing wire group is energized, a magnetic field opposite to the direction of the magnetic field of the permanent magnet is generated, that is, the magnetic flux of the permanent magnet is reduced, and the attraction of the permanent magnet to the armature and the spring sheet at the rear of the printing needle is canceled, so that the spring sheet drives the printing needle to fly forward and complete the printing action. The advantages of this type of printhead are low power consumption and fast printing speed.

The basic working principle of a dot matrix printer:

The dot matrix printer uses the principle of mechanical and circuit drive to make the printing needle hit the ribbon and the printing medium, and then print out the dot matrix, and then form characters or graphics from the dot matrix to complete the printing task. In the online state, the printer receives the print control command, character printing or graphic printing command sent by the PC through the interface, and then after processing through the CPU of the printer, it looks for the first column address (when printing in the forward direction) or the last column address (when printing in the reverse direction) corresponding to the image code corresponding to the character or figure from the font library, so that the code is found out one by one and sent to the print head driving circuit, and the print head is stimulated to print the dot matrix printer.

Structure of a dot matrix printer:

The dot matrix printer consists of two parts: "printing mechanism" and "control drive circuit", and there are three kinds of mechanical movements in the printing process: the horizontal movement of the print head, the longitudinal movement of the printing paper, and the stylus movement of the printing needle. These movements are controlled by software, and the drive system is carried out by some precision machinery.

The dot matrix dot matrix printer uses the diameter of the print needle to drive the print needle to hit the ribbon forward through the electromagnet in the print head to hit the ribbon, and the ink dot is printed on the printing paper to complete the printing action. So, a dot matrix dot matrix printer is actually a mechatronic system. It consists of two main parts:

Mechanical part and electrical control part. The mechanical part mainly completes the tasks such as the horizontal left and right movement of the print head, the longitudinal movement of the printing paper and the cyclic movement of the printing ribbon, and the electrical control part mainly completes the printing data and control information received from the computer, converts the data in the form of ASC code transmitted by the computer into printing data, controls the action of the printing needle, and controls the action of the stepping motor of the word car and the stepping motor of the paper feeding according to the requirements of the printing format, and detects the working status of the printer in real time.