X-Rite 939, Operator'S Manual

Page: 91 / 108

C H A P T E R F I V E
5-34
Trap
The Trap function determines how well one ink prints over
another ink (overprinting). You should select the Trap Mode
(formula) located in the Configuration menu before measuring
(refer to Section Four)
.
Trap is calculated using one of two formulas:
Preucil (GATF) Trap formula
(factory default)
T
D D
D
P
OP
=
−
×
1
2
100
Brunner Trap formula
( )
T
B
=
−
−
×
−
− +
1 10
1 10
100
1 2
D
D D
OP
Where:
•
D
OP
= Density of overprint - paper
•
D
2
= Density of 2
nd
ink - paper
•
D
1
= Density of 1
st
ink - paper
To access the Trap function:
1.
Use the Tab keys
$@
to highlight
Trap
.
–
M A I N M E N U
–
↑
O p a c i t y
D e n s i t y
D o t / T o n e
T r a p
↓
X — R i t e
9 3 9
— — — — — —
X X X X
* * * * * *
2.
Press the Enter key
#
to access the Trap function.
Measuring Paper
The instrument takes the density value of the paper and
automatically subtracts it from subsequent trap measurements.
To measure paper:
1.
If not selected, press the Tab keys
$@
to highlight Paper.
<
Measure Paper
> appears in the user dialog. The paper
values displayed are the current values set in the
instrument.