Techkon DENS, Руководство пользователя

Страница: 10 / 22

10
Manual TECHKON DENS
How to measure
After switching DENS on, it is instantly ready to measure. Just position the measure-
ment aperture on top of the measurement sample and press shortly with the index
finger the DENS button. Within less than one second the resulting measurement value
will appear on the display of the device.
Please ensure that the device always has a firm stand on a flat surface. There must not
be a distance between the measurement head and the sample where light could pass
through, because this can influence the measurement.
The color of the background material underneath the measurement sample can have
an influence on the measurement result. Different technical standards describe which
backing material to use. In the printing industry the following procedure is widely used:

white backing for proofs and

black backing for prints.
Calibration
Prior to every series of measurements a calibration should be carried out. After a cali-
bration the device is long term stable, however it is recommended to perform a cali-
bration before starting a new measurement task just to be sure the device is working
properly.
For density measurements according to Status ISO E / Pol the calibration is carried out
on paper white. This will ensure that the density values are in direct ratio to the ink
thickness which is applied on the paper. When there is a change in the paper type, a
new calibration has to be done.
When a calibration according to Status ISO T / no Pol is carried out an absolute white
standard is used (see enclosed reference card).
For dot % measurements in transmission a calibration is done on a unexposed spot of
the film to be sure, that no “veil” on the film will falsify the dot % value.
A calibration is as easy to carry out as a measurement: Place the measurement head
on top of a blank area of the paper sheet or the absolute white standard. The calibra-
tion can be started now by pressing the CAL button. A successful calibration will be
indicated be three horizontal lines. The device is now ready for measurements.
During the calibration process always take care that the instrument is on a flat, stable
surface and that the material backing the paper is the same as for the following mea-
surements (white, gray or black). When the paper sample is printed on both sides, it
is recommended to use a black backing material in order to avoid mismeasurements
due to color shining through the back of the opaque paper.