By heating the coated thermo chromic paper or the thermal paper, printed image is produced in thermal printers. Paper is passed over the thermal printer head. The areas where it is heated, it becomes black and the image is produced. There are also the printers which are two color direct thermal printers. They are used to create the image which are both; the black and white image and the colored image by applying heat at two different temperatures. They use heat sensitive paper but there are some printers which are thermal transfer printer. They use heat sensitive ribbon for the printing. There are some of the key components of the thermal printer like thermal head, platen, spring and controller boards. Thermal heads are used to generate the heat and prints the paper. Platen is a rubber roller which is used to feed the paper. Spring is the component which is used to apply the pressure to the thermal head and then it contacts with the thermo sensitive paper. Controller heads are used to control the mechanism.
Thermo sensitive paper is inserted in the thermal head and the platen to print the paper. Heat is generated by sending electrical current to the heating elements of thermal head. The thermo sensitive coloring layer of the thermo sensitive paper is activated by the heat. It changes the color of the place where the heat is applied. This printing mechanism is called thermal system. The thermal printers are dot matrix printers as the heat elements are a matrix of closely related and spaced dots.
There is solid state mixture of dye and suitable matrix in the paper. It is a combination of a fluoranleuco dye and an octa decyl phosphonic acid. The dye reacts with the acid when the matrix as heated above of its melting point. It is then shifted to the colored form. when the matrix solidifies back quickly enough then this form is then changed into the meta stable state. For the management of the thermal printers mechanisms, the controller boards are embedded with the firmware. There are multiple bar code types, graphics and the logos which are managed by the firmware. User can choose among different resident fonts and the sizes of the characters. There are various sensors which are derived by the controller boards. These sensors can be paper low, paper out, door open, top of form and many more. There are multiple interfaces like RS-232, parallel, USB and wireless. Thecash drwaer is also maintained and controlled for the point of sale applications.
Tips and comments
As compared to the impact dot matrix printers, the thermal printers print the pages quietly and fast. They are ideal for the portable and the retail applications, as they consume less power, they are smaller in size and lighter. There are some kinds of printers like roll based printers. They can be rapidly refilled. There are some of the commercial applications of thermal printers and these are filling station pumps, point of sale systems, voucher printers in slot machines, information kiosks, print on demand labels for shipping, and the strips on the hospital cardiac monitors for recording live rhythm.