1. Field of the Invention
The present invention relates to a color printer which sprays ink of various colors such as yellow, magenta, cyan and black onto the recording medium in order to make color print-outs.
2. Description of the Prior Art
For printing out figures and characters in multiple colors, an on-demand ink jet printer is conventionally used which prints out figures and characters in color by a mixture of cyan, magenta, yellow and/or black inks loaded on the printer.
FIG. 1 shows the construction of such conventional on-demand ink jet printer. As shown, the printer has slide shafts 2 and 3 mounted parallel to each other in front of a platen 1. A carriage 4 is supported by the slide shafts 2 and 3 so as to be horizontally movable along the platen 1.
The carriage 4 is driven by a pulse motor (not shown) which is connected with the carriage 4 through wire. The carriage 4 contains an ink tank 5 and moves rightward for printing operation.
The ink tank 5 is provided with a printer head 6 on the side facing the platen 1. Four ink cartridges 7, 8, 9 and 10 of different color inks are inserted in the ink tank The cartridges 7, 8 and 9 are for the three primary color inks; yellow, magenta and cyan, and the cartridge 10 is for black ink. The three primary color inks are mixed as necessary on the recording medium in printing out picture elements of multiple colors.
FIG. 2 is a front view of the printer head 6.
Four orifice groups 6Y, 6M, 6C and 6B are horizontally arranged on the printer head 6 and each group consists of four vertically aligned orifices 11, 12, 13 and 14. From right to left in the printing direction, the orifice groups 6Y, 6M, 6C and 6B are for yellow, magenta, cyan and black inks, respectively. The orifices 11, 12, 13 and 14 in each group correspond to four vertical recording dots for a picture element. The four orifice groups are horizontally spaced from one another by eight-dot equivalent distance. Each of the four orifices 11, 12, 13 and 14 in each group is aligned on the same line with the corresponding orifices in the other groups.
Although the above conventional color printer is generally used for colored figure printing, it is also demanded as an ordinary printer which prints out characters in black.
That is, the demand for multi-purpose printers which can print out not only color figures but also characters of high definition is growing in recent years.
The printer head of the above conventional color printer is, however, designed for color figure printing with the space of 1/120 inches between the vertical recording dots. Therefore, high speed character printing is not possible with this printer head.
In other words, the conventional color printer is very slow in character printing operation. Besides, the characters printed out are of poor definition. In short, the conventional printer functions poorly as a character printer.
USPTO Backgrounds
USPTO Backgrounds