An overview of impact printing
This paper gives an overview of impact printing and reviews some of the more recent advances made in this printing technology. Matrix and fully-formed-character impact-printing technologies are discussed for both serial printers and line printers. The critical electromechanical subassemblies that are described are the hammer unit, the paper-handling system, the inking system, and the type-element system. The mathematics describing printer performance and the operation of some of the subassemblies are presented. The relative simplicity of the impact printer still allows it to be the most economical form of text printing. Its other advantages are reliability, general insensitivity to environment, and the ability to print on the greatest variety of print media.
THE ROLE OF OUTPUT DEVICES IN THE HIGHER EDUCATION OF CARTOGRAPHY
The rapid development of information technology affected cartography considerably in the last four decades of the 20th century. Traditional offset printing methods were developed neither by and nor for cartography. In the cartographic curriculum, however, these techniques were taught to let cartographers control/evaluate the final phase of map making. The first digital output device used by cartographers (and also by students in the higher education) was the pen plotter. Other type of early computer printers (line printers and dot matrix printers) were only used at large firms, but their output was of very poor quality for cartographic purpose. Colour dot matrix printers were able to print colour maps, but both the speed and quality was insufficient. This technology was soon replaced by inkjet printing, which is still the most common and most affordable method (even in large format). In higher education curricula, the reproduction process was taught as an independent subject or a part of other related subjects. Cartographers should know the complete technical process to be sure that the maps will be reproduced as they were planned. In the second phase, when the digital output devices became wide-spread and higher education institutions could afford these devices, the course on map reproduction was completed with digital methods, and the necessary theoretical information about the process was also added. In the third phase, when the output device became easily available for even home users, the traditional offset printing method has seemingly lost its importance, and the students became rather interested in the digital printing methods. Nowadays, the most important output devices in cartography are the screen of the computer, mobile phone, and PDA, which again made us introduce changes in the curriculum.
Theory and applications of step motors
Theory and applications of step motors , Theory and applications of step motors , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی