Epson FX-185 User Manual - Page 67

Figure 3-1 shows one each of lower- and uppercase letters. The p gives an example of the way a few lowercase letters use the bottom two rows of the matrix. All numbers, uppercase letters, and most symbols are formed within the top seven rows of the matrix. Main columns The construction of the print head restricts the maximum height of any character to nine dots. As shown in Figure 3-2, the print head uses a vertical column of nine pins (actually, wires). Because there is only one column of pins, the head must move sideways sequentially to each of the different column positions of the matrix, then fire the appropriate pins. Electrical impulses cause the FX to fire pins at the paper. As a pin is fired, it presses against the ribbon to produce one dot of the matrix. At each position, the printer fires only the pins that are necessary to print the current column of the character. Figure 3-2. The print head To print a capital H as in Figure 3-2, the print head fires pins 1 through 7 in column 1; pin 4 in columns 2 , 3 , and 4; and pins 1 through 7 again in column 5. 50