13.2.1 Red Illuminator
The red illuminator is made up of eight LEDs which are all
controlled simultaneously by the software application.
These are Bright Field general purpose illuminators used in
the operating distance range from 20 mm to 550 mm. The
reader focus distance further limits this range.
The red illuminator is an optimum solution for applications
where codes are printed on paper and where Direct Part
Marking (DPM) is obtained by ink jet or laser etching
technology on flat non-reflective surfaces, without any
evident machining flaws made by machine tools (that is,
cutters or lathes). The reader's pitch or skew angle helps
avoid direct reflection when codes are marked on very
reflective surfaces.
Figure 169. LED Red Illuminator
13.2.2 Multicolored DPM Illuminator
This is both a Bright Field and a Dark Field illuminator.
The Multicolored DPM illuminator is made up of 63 LEDs
divided into two groups of four sectors each which are
independently controlled by the software application.
Four sectors of six LEDs each make up the internal group
called Central LED Group and correspond to Bright Field
illumination. The operating distance range is typically from
20 mm to 250 mm. The reader focus distance further limits
this range.
The use of the Multicolored DPM Central LED Group is
particularly effective in direct part mark applications (DPM),
where linear machining flaws are present on the part
surfaces. In fact, in these cases, an image of the code can
be obtained having a very light background.
The other four sectors make up the external group called
Peripheral LED Group and correspond to Dark Field
illumination. Dark Field illumination is guaranteed by the 39
side-emitting blue LEDs divided as follows: a TOP sector of
seven LEDs, a BOTTOM sector of eight LEDs and two
sectors (LEFT and RIGHT) of twelve LEDs each.
Figure 170. 39/24 LED Multicolored DPM Illuminator
The Peripheral LED Group can be the correct solution for DPM applications with highly reflective surfaces. In these
applications, by using a traditional bright field illuminator, the code can result unreadable. This is because in the acquired
image some parts of the code are made invisible due to gray-level saturation generated by direct reflection of the illuminator
LEDs.
To obtain optimum Dark Field illumination, it is necessary to work at close range, typically in the range from 20 mm to 50
mm. The reader focus distance further limits this range.
An orange filter is applied over the Central LED Group to avoid harmful blue light reflections off the Peripheral LED
component packages.
The Peripheral LED Group can also be used as a Bright Field illuminator in the range from 50 mm to 100 mm.
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