Epson LQ-1000 User Manual - Page 81

Dot Patterns, Eight-pin Graphics, Twenty-four-pin Graphics, Pin Labels

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Dot patterns The LQ's print head is able to print graphics as well as text because graphic images are formed on the LQ about the same way that pictures in newspapers and magazines are printed. If you look closely at a newspaper photograph, you can see that it is made up of many small dots. The LQ also forms its images with patterns of dots, as many as 360 dot positions per inch horizontally and 180 dots vertically. The images printed by the LQ can, therefore, be as finely detailed as the one on the first page of this chapter. Eight-pin graphics So that it is compatible with the many programs written for such printers such as the Epson FX and RX series, the LQ has an 8-pin graphics mode with six densities. Although this mode uses only one third of the LQ's pins, it produces good quality graphics and allows you to use the many programs written for 8-pin graphics. Twenty-four-pin graphics The graphics mode that takes full advantage of the LQ's print head is 24-pin graphics. It has five densities, but for simplicity this explanation will begin with only one of them, triple-density. Triple-density prints up to 180 dots per inch horizontally. As the print head moves across the paper, every 1/180th of an inch it must receive instructions about which of its 24 pins to fire. At each position it can fire any number of pins from none to 24. This means that the printer must receive 24 bits of information for each column it prints. Since the LQ uses 8-bit bytes of information in its communication with a computer, it needs three bytes of information for each position. Pin labels To tell the printer which pins to fire in each column, you first divide each of the vertical columns into three sections of eight pins each and consider each section separately. Since there are 256 possible combinations of the eight pins in each section, you need a numbering system that allows you to use a single number to specify which of the 256 possible patterns you want. This numbering system is shown in Figure 6-1. 6-3

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Dot patterns
The LQ’s print head is able to print graphics as well as text because
graphic images are formed on the LQ about the same way that pic-
tures in newspapers and magazines are printed. If you look closely at a
newspaper photograph, you can see that it is made up of many small
dots. The LQ also forms its images with patterns of dots, as many as
360 dot positions per inch horizontally and 180 dots vertically. The
images printed by the LQ can, therefore, be as finely detailed as the
one on the first page of this chapter.
Eight-pin graphics
So that it is compatible with the many programs written for such
printers such as the Epson FX and RX series, the LQ has an 8-pin
graphics mode with six densities. Although this mode uses only one
third of the LQ’s pins, it produces good quality graphics and allows
you to use the many programs written for 8-pin graphics.
Twenty-four-pin graphics
The graphics mode that takes full advantage of the LQ’s print head
is 24-pin graphics. It has five densities, but for simplicity this explana-
tion will begin with only one of them, triple-density.
Triple-density prints up to 180 dots per inch horizontally. As the
print head moves across the paper, every 1/180th of an inch it must
receive instructions about which of its 24 pins to fire. At each position
it can fire any number of pins from none to 24. This means that the
printer must receive 24 bits of information for each column it prints.
Since the LQ uses 8-bit bytes of information in its communication
with a computer, it needs three bytes of information for each position.
Pin labels
To tell the printer which pins to fire in each column, you first divide
each of the vertical columns into three sections of eight pins each and
consider each section separately. Since there are 256 possible combina-
tions of the eight pins in each section, you need a numbering system
that allows you to use a single number to specify which of the 256
possible patterns you want. This numbering system is shown in Figure
6-1.
6-3