Print-Quality Concepts; Printing Characteristics Defined; Print-Quality Measuring Devices - IBM 1403 Field Engineering Maintenance Manual

Print quality is an important consideration with any
mM
1403 Printer. However, where the output of a 1403
is
used for input to an optical-character-recognition
system, quality of printing becomes a prime consider-
ation.
This is because an
IBM
1403 Printer that is producing
printing that is entirely satisfactory to customers who
are visually reading the output may not be producing
printing with the characteristics needed for low reject
rates in reading machines.
Printing Characteristics Defined
Some of the terms in this manual are unique to the sub-
ject of print characteristics. Definitions of these terms
follow.
Average Edge
The typical edge· of a printed character is not a straight
line. The term average edge is defined as an imaginary
line that bisects the edge irregularity (Figure 95).
Average edges of characters need to be clearly indi-
cated because of the way in which the character recog-
nition-logic of the optical-character reader is designed.
Stroke Width
A stroke is a portion of a character (Figure 96). It can
~ be a vertical, horizontal, curved, or slanted segment.
:.·SJr.oke.width is the distance between the average edges
'~~f
the stroke.
Density
"'Density, or ink coverage, is the blackness of a charac-
. ter. This. is determined visually by comparing the
character to a comparative density chart.
Figure 95. Average Edge and Stroke-Width
Print-Quality Concepts
Contrast
Contrast is the difference in density measurement be-
tween the character and the background area. This can
also be defined as the difference between print reflec-
tion from the printed character and background reflec-
tion from the surface of the document.
Extraneous Ink
Extraneous ink (or other particles) is any spot appear-
ing within the reading area not between the average
edges of the character. This condition (Figure 97) can
be caused by streaks, smears, or splatter. No extrane-
ous ink (or particle) whose area is equal to or greater
than a half-cell area is acceptable (Figure 98).
Phantom Printing
Phantom printing means printing an unwanted charac-
ter that is the next one in sequence on the chain .150"
away from the desired character.
Voids
A stroke void in a character (Figure 99) is a light spot
that is completely surrounded by ink and is vis able to
the experienced eye without the aid of a magnifying
device. A character void is a light spot that is not com-
pletely surrounded by ink and is visable to
the~e~~:
enced eye. . . -"
Slur
A slur is ink that is not a part of the average character
outline. Smears, phantom printing, etc., are also in-
cluded in this category.
Print.Qualify Measuring Devices
At present, two types of gages are available for meas-
uring print quality.
-:- --\-
-
----- : L-(D
I
... - - - - ( 2
I
i~
- - - - _ 1 ____ -
Figure 96. Character Stroke
The three strokes that make up
the character "One " are drawn
by the datted lines.
95