Working principle of needle printers

The printer itself is a micro-computer 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 start to work. The CPU can receive all kinds of control instructions from the panel or from the host, and interpret and execute all kinds of instructions. These connections are made through computer interfaces. There are two working modes of needle punching: Text Mode and Bit Image Print Mode.

Text style

Printed data of needle printer is obtained from host computer through interface with computer. The printer’s printed data is the ASCII codes of the characters to be printed, which are stored in the print buffer of the printer. The printer sends a BUSY (busy) signal to the host after each time the data transmitted by the host is filled with the print buffer. When the host receives the signal, it pauses sending data, and then the printer starts printing.

After printing begins, the CPU in the printer takes out the ASCII code of the printed character from the print buffer, and calculates the first address of the character lattice storage area corresponding to the character. Take out the dot matrix code of each column one by one according to the address, drive the printing needle, hit the ribbon, and form the printing characters on the printing paper. There are 96 ASCII codes and some special character font codes in the printer’s character generator ROM (some printers also have dot matrix codes of Chinese characters, such as LQ-1600K). When the data printing in the buffer is completed, the printer is opened again to receive the new printed data from the host and start the new printing process.

If you need to print graphics or Chinese characters (for printers without Chinese character library), the host can send out the pixel signal of graphics or Chinese character font code. Obviously, this printing method is similar to that of displaying characters on the display.

Bit mapping

In this way, the print data sent by the computer is the data that controls the pin-out and pin-closing of the printing needle, so the programmer can directly write a program to control each pin and print out the graphics, tables and Chinese characters.

The technical support content was provided by v4ink, a compatible toner cartridges seller

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