SPECTRO-3 -
The new color sensor series of Sensor Instruments
With the
SPECTRO-3 series there now is a
family of color sensors that have been
specifically designed for "true-color" detection ("human visual reception") and
high switching frequency. The sensors can be used both in AC and in DC
operation with integrated or externally controlled light source.
With
the included SPECTRO3-Scope Windows® software illumination can also be
turned off (OFF mode) with a simple mouse-click - which also allows the
detection of the L*u*v* color value of self-luminous objects such as LEDs,
automobile tail lights, fluorescent lamps, or e.g. the color of flames. Up to
31 colors can be output through the 5 digital outputs, the typ. maximum
switching frequency is 30 kHz. Apart from a white-light source, a
high-performance UV lights source also is available and allows color detection
and differentiation of fluorescent colors without any problems. Different
front-ends make it possible to implement operating distances of almost 0
through to approx. 500 mm, with detection areas of a diameter of 0.5 mm to 100
mm. The use of optical fibres (approx. 50 different versions) allows
applications in Ex areas (zone 0). Apart from the optical fibre types (FIO
group) there also are the types of the DIL
group (diffuser), which primarily are used for applications where the gloss
effect of the objects to be inspected has to be suppressed. For objects with an
extremely high gloss, however, it is recommended to use the
POL group (polarisation filter), while the
FCL group is especially used for applications
requiring a differentiation between glossy and diffuse objects. If the
application requires a color detection of small objects, the suitable sensors
are of the FIO group or of the
COF group (transmitter and receiver optics
arranged cofocally), which allow a reliable detection of smallest objects at a
distance of 30 mm or 50 mm, respectively.
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Extensive
range of optical fibres for the new SPECTRO-3-FIO series
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different optical fibre sensor head versions are now available for the new
SPECTRO-3-FIO color sensor series. Optical fibre cross-sections range from
Ø 0.6 mm to Ø 10 mm, or 3 mm x 0.5 mm up to 88 mm x 0.15
mm.
Light is emitted at the front side either axially or at an angle of
90°. The micro-fibres are available in different lengths and are provided
in sturdy, industry-type quality. For the most important sensor head versions
there also are front-ends that allow a larger distance from the object with a
smaller light spot size (up to 150 mm). Furthermore, the color sensor can be
operated with the external light sources SI-ELS and
SI-ELS-UV, which for example allows the detection of color marks or
fluorescent color marks.
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Color checking
of structured and inhomogeneous surfaces
With many objects requiring
color checking an inhomogeneous surface causes problems in color determination.
A structured surface, for example, leads to gloss rate fluctuations that cause
difficulties for conventional color sensors because depending on the gloss rate
the color is sometimes detected more intensively and sometimes less
intensively, and the actual color that depends on the respective gloss rate of
the surface, is brightened or "softened" by direct reflection. With the
SPECTRO-3-50-DIL color sensor, diffuse
illumination considerably reduces this gloss effect.
Furthermore,
optical averaging of structural fluctuations is performed with the help of the
large measuring range (measuring spot typ. 20 mm at a distance of 50 mm), and
the color is thus reliably detected.
The true-color color detector
("human color perception") and the evaluation software ("human color
assessment") furthermore guarantee that even smallest color differences of
different objects are reliably detected.
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Reliable and
fast color detection at a large distance
The
SPECTRO-3-FCL series now also allows color
detection at a large distance. Depending on the version and on the object, a
distance of up to 500 mm can be realised. The sensor is equipped with
super-bright white-light LEDs and a so-called true-color chip that perceives
colors like the human eye. Up to 31 colors an be taught. During operation the
sensor determines the color reference that comes closest to the current color
sample ("human color interpretation").
Teaching either can be performed
under Windows® with the supplied SPECTRO3-Scope software, through the
INØ pin, or with the TEACH button that is integrated at the sensor
housing. Color scanning is performed with a scanning frequency of up to 40 kHz,
the switching frequency of the sensor is 30 kHz. The sensor unit is integrated
in an M34 aluminium housing, the optics unit is protected by a scratch-proof
glass cover, which makes the sensor suitable for rough industrial
use.
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High-speed
color sensor with integrated gloss suppression
Color inspection of
glossy objects primarily depends on correct illumination. For example, when
directed light is used, i.e. light that is directed onto the object at a
certain angle, the color detector apart from the actual object color also
receives influences due to direct reflection of the transmitter light depending
on the gloss rate of the object. The actual object color thus is distorted due
to the influence of direct reflection, the colors become smoother, red for
example is recognised as pink, blue as bright blue, etc.
With the
color sensors of the SPECTRO-3-DIL series the effect of direct reflection
is considerably suppressed by using diffuse light, colors are detected much
more clearly, and a reliable color differentiation of differently colored
glossy objects is thus possible. Up to 31 color references can be stored in the
sensor, and the sensor determines the color reference that comes closest to the
current color sample. A true-color chip is used as color detector ("human color
perception"). Inspection is performed at a scanning rate of 40 kHz and a
switching frequency of the digital outputs (5 outputs) of 30 kHz. With its
compact M34 aluminium housing and the glass cover of the transmitter and
receiver optics the SPECTRO-3 color sensor is excellently suited for rough
industrial use.
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High-speed
color detection of fluorescent objects
Conventional luminescence
sensors that are available on the market are able to detect whether there is a
fluorescent object, but they utterly fail when they should perform color
differentiation of such objects! With the luminescence color sensors of the
SPECTRO-3-UV series there now are sensors that
apart from brightness differentiation (grey scale evaluation) also can perform
color differentiation. Up to 31 different fluorescent objects can be stored in
the sensor's color memory. The color information is provided via 5 digital
outputs, a serial interface also is available.
Teaching of the
fluorescent objects can be performed either under Windows® with the
included SPECTRO3-Scope software, with the TEACH button that is integrated at
the sensor, or through digital input INØ. With its compact (M34 housing)
and sturdy design the sensor is excellently suited for rough industrial
use.
The 40 kHz scanning frequency and the 30 kHz switching frequency
also guarantee a reliable detection and recognition of fast-moving fluorescent
markings.
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High-speed
color detection of small objects at a great distance
The confocal
sensors of the SPECTRO-3-COF series project
white-light spots with a diameter of approx. 1 mm to 5 mm or with dimensions of
4 mm x 0.7 mm onto the object to be detected. The transmitter optics unit is
located at the centre of the receiver optics unit, which results in a highly
compact design. This allows a reliable, high-precision, and high-speed
detection of small objects such as e.g. color markings or wires at a great
distance.
The color sensor features 5 digital outputs; teaching of up to
31 colors can be performed with the included SPECTRO3-Scope Windows®
software, with a Teach-button at the sensor housing or with a Teach-input for
external teaching. With a scanning frequency of 40 kHz and a switching
frequency of 30 kHz the color mark detector definitely ranks among the faster
systems. Reliable color differentiation on the one hand is guaranteed by the
so-called true-color detector (human color perception), and on the other hand
by a special evaluation algorithm. The color that is currently placed under the
sensor is compared with the color references (up to 31) that are stored in the
color memory. Similar to human evaluation the color sensor software first
performs a pre-selection of references (possible candidates) whose tolerance
range includes the current color. From the possible reference colors it then
selects the one color that is closest to the current color (direct comparison).
Only this process allows the detection even of smallest color differences (to
ΔE=0.3).
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Color
inspection of glossy objects
In practice, the reliable detection of
the color of glossy objects usually is extremely difficult because the actual
color information is mixed with direct reflection resulting from the gloss
effect. A rich color thus is turned into a "soft" color, because the direct
reflection of the color sensor's light source does not contain any color
information. Red thus is recognised as pink, blue as bright blue,
etc.
In the SPECTRO-3-50-POL color sensor,
integrated polarisation filters prevent such direct reflection, the actual
color thus can be clearly recognised and reliably detected. Parameterisation of
the sensor is considerably facilitated by the included SPECTRO3-Scope
Windows® software. This software provides various evaluation modes, teach
functions, and trigger possibilities. A detected color is output via 5 digital,
npn- and pnp-capable outputs, and via a serial interface (RS232, USB and
Ethernet). The switching frequency is approx. 30 kHz.
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Human visual
perception, only 1000 times faster
The new SPECTRO-3-FIO series now
also allows the detection of color marks with a scanning frequency of 40 kHz.
With a high-power LED white light is fed into an optical fibre bundle, and via
cross-section converter and attachment optics unit is projected onto the color
mark to be detected as a light spot measuring 4 mm x 0.7 mm or 2 mm x 0.2 mm,
or having a diameter of 0.5 mm. A part of the light impinging on the color mark
is scattered back into the attachment optics unit and through the optical fibre
bundle is directed onto the true-color detector that recognises the color of
the object similar to human visual perception. With different attachment optics
units, object distances of >0 mm up to approx. 200 mm can be realised. Due
to the use of an optical fibre the color inspection system also can be used in
Ex areas without any problems. Compressed-air attachment units can be provided
as protection against excessive dirtying.
With a Windows® user
interface the color sensor can be correspondingly parameterised via RS232, USB
and ETHERNET. The software also provides various evaluation
methods.
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High-speed,
high-precision color mark detection with the SPECTRO-3-FIO - also suitable for
Ex areas
The SPECTRO-3-FIO is a
color mark detector that detects color like a
human, but with a considerably higher frequency of approx. 40
kHz.
Through a special reflected-light optical fibre white light that is
provided by a super-bright white-light LED is directed onto the color mark to
be detected. Various optical fibres and attachment optics units are available
to allow a highly precise color mark detection. At a distance of approx. 10 mm
from the object, the light spot thus may have a diameter of Ø 0.5 mm or
dimensions of 2 mm x 0.2 mm or 4 mm x 0.7 mm. The light that is scattered back
from the color mark towards the reflected-light optical fibre impinges on a
so-called true-color detector that divides the light into a red, green, and
blue component.
The controller that is integrated in the sensor then
performs color calculation acc. to the L*a*b* method, and can select the
suitable color from up to 31 stored color marks.
Due to the use of
optical fibres the system also is suitable for Ex area applications, where for
optical fibre lengths of more than 2 m the external
white-light source SPECTRO-3-ELS is available.
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Color
measurement of self-luminous objects with the SPECTRO-3-FIO
With the
SPECTRO-3-FIO color sensor there now is a system
that ideally can measure different light sources similar to human visual
perception. This is achieved by the "true-color detector" that is integrated in
the sensor, and by corresponding software evaluation algorithms. The so-called
L*,u*,v* value provides information about the brightness and about the
red/green and yellow/blue color value of the light source. An extensive range
of optical fibres and attachment optics units allows optimal matching of the
sensor system to the respective light source. The required dynamic range is
achieved by way of eight software-selectable gain stages. Optical attenuation
filters are available for super-bright light sources.
Up to 31 light
sources can be stored (taught) in the SPECTRO-3-FIO, the tolerance ranges for
the individual taught color states can be preset with the software. The sensor
provides the information about the detected color state by way of five digital
outputs.
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New
SPECTRO3-Scope Windows® user interface for the SPECTRO-3 series
The SPECTRO3-Scope software was developed
specifically for the parameterisation and data monitoring of color sensors of
the SPECTRO-3 series.
The software allows
the selection of different illumination modes such as AC (modulated light), DC
(constant light), Pulse (pulsed operation) or OFF (self-luminous object). In
case of AC, DC, or PULSE mode the brightness of the light source can be set. In
all four modes the gain of the color detector can be set in 8 stages.
The software furthermore allows the setting of a trigger type (external
trigger, self-triggering, or continuous), the selection of various color
evaluation methods x,y,INT, SiM (evaluation acc. to L*a*b*) and L*u*v* in case
of self-luminous objects, and color modes (BEST HIT, FIRST HIT, MINIMAL
DISTANCE, COL5).
With the color modes the current object color is
compared with up to 31 references (that can be taught by the user) according to
different criteria. Supposedly the most efficient and mostly used mode is the
BEST HIT mode, which first selects the possible references from the stored
color references (selection of candidates) and then performs an exact
comparison with the candidate. The SPECTRO-3 sensor then selects the candidate
that is closest to the current object color. Parameterisation furthermore is
facilitated by extensive data monitoring, displaying both the raw data, the
detected reference color, and the calculated values such as SiM, L*u*v*, xyINT
in graphical and numerical form. Operation is further facilitated by a data
recorder, a calibration function, and by teaching not only to single objects,
but to a series of objects of the "same" color. The possibility of forming
color groups that allows the combination of several taught colors on one
switching output, also is worth mentioning.
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High-speed
fluorescent color mark detection with the SPECTRO-3-FIO-UV
With the
super-bright UV light source SI-ELS-UV and the
SPECTRO-3-FIO-UV evaluation unit there now is a
color sensor system that not only performs high-speed detection of fluorescent
color marks, but also is able to perform differentiation by fluorescent color
and brightness. Objects are detected with a scanning frequency of typ. 40 kHz
at a distance of approx. 12 mm between sensor head and object. Depending on the
employed optical fibre and front-end the spot size may have a diameter of 0.7
mm or dimensions of 2 mm x 0.2 mm or 4 mm x 0.7 mm.
The included
SPECTRO3-Scope Windows® operator software allows the teaching of up to 31
colors and the selection of various evaluation methods (L*, u*, v* or x, y,
INT) and evaluation modes (BEST HIT, FIRST HIT, MINIMAL DISTANCE, SELFTRIGGER).
Since the system uses reflected-light optical fibres, the detection of
fluorescent marks also can be performed in Ex areas (zone 0) without any
problems. Optical fibres of various lengths are available.
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Insensitive to
extraneous light, non-contacting, and high-speed inline color measurement
L*a*b* inline color measurement according to the 45°/0°
method under illumination similar to D65 with a true-color detector (color
curves identical to the human eye) now is possible with the
SPECTRO-3-45°/0° color measuring
system.
Closeness to the D65 standard light curve is achieved by a
combination of special white-light LEDs, blue-light LEDs, and optical filters.
The use of LEDs furthermore allows light modulation, which prevents influences
of extraneous light on the measuring result. The color sensor provides the
color values in digital, serial form. The system furthermore features 5 digital
outputs that allow the output of up to 31 stored colors (L*, a*, b* values).
The distance between color measuring system and object is approx. 30 mm, the
typical measuring range is 10 mm.
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