U.S. patent application number 15/579663 was filed with the patent office on 2018-05-31 for method for accurate population of a circuit carrier.
The applicant listed for this patent is ZKW GROUP GMBH. Invention is credited to Dietmar KIESLINGER, Jurgen ZORN.
Application Number | 20180153064 15/579663 |
Document ID | / |
Family ID | 56119247 |
Filed Date | 2018-05-31 |
United States Patent
Application |
20180153064 |
Kind Code |
A1 |
ZORN; Jurgen ; et
al. |
May 31, 2018 |
METHOD FOR ACCURATE POPULATION OF A CIRCUIT CARRIER
Abstract
A method for accurate population of a circuit carrier (2) with
at least one electronic component (1) which comprises at least two
separately controllable light-emitting surfaces (3a, 3b, 3c),
having the following steps: a) optically detecting current
positions of the at least two light-emitting surfaces (3a, 3b, 3c)
of the electronic component (1); b) calculating at least one
current variable (S.sub.ist) characterizing the geometric location
of the light-emitting surfaces (3a, 3b, 3c) according to the
current positions of the at least two light-emitting surfaces (3a,
3b, 3c) of the electronic component (1); c) comparing the at least
one current variable (S.sub.ist) to at least one target variable
(S.sub.soll) for calculating at least one correction variable (k);
d) populating the circuit carrier (2) with the at least one
electronic component (1) according to the at least one correction
variable (k).
Inventors: |
ZORN; Jurgen; (Rossatz,
AT) ; KIESLINGER; Dietmar; (Theresienfe, AT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ZKW GROUP GMBH |
Wieselburg |
|
AT |
|
|
Family ID: |
56119247 |
Appl. No.: |
15/579663 |
Filed: |
June 2, 2016 |
PCT Filed: |
June 2, 2016 |
PCT NO: |
PCT/AT2016/050173 |
371 Date: |
December 5, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H05K 13/08 20130101;
F21S 41/657 20180101; H05K 3/303 20130101; F21S 41/141 20180101;
H05K 13/0812 20180801; Y02P 70/50 20151101; H05K 1/181 20130101;
H05K 13/046 20130101; H05K 2201/10106 20130101; H05K 13/0813
20180801; H05K 2203/166 20130101; Y02P 70/613 20151101; F21Y
2115/00 20160801; G01B 11/14 20130101 |
International
Class: |
H05K 13/08 20060101
H05K013/08; H05K 1/18 20060101 H05K001/18; F21S 41/141 20180101
F21S041/141; F21S 41/657 20180101 F21S041/657; H05K 3/30 20060101
H05K003/30; G01B 11/14 20060101 G01B011/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 9, 2015 |
AT |
A 50469/2015 |
Claims
1. A method for accurate population of a circuit carrier (2) with
at least one electronic component (1) which comprises at least two
separately controllable light-emitting surfaces (3a, 3b, 3c), by
which position errors of the light-emitting surfaces (3a, 3b, 3c)
on the electronic component are detected and compensated for by
calculating a correction variable (k), the method comprising: a)
optically detecting current positions of the at least two
light-emitting surfaces (3a, 3b, 3c) of the electronic component
(1) with respect to a reference point; b) calculating at least one
current variable (S.sub.ist) characterizing the geometric location
of the light-emitting surfaces (3a, 3b, 3c) according to the
current positions of the at least two light-emitting surfaces (3a,
3b, 3c) of the electronic component (1); c) comparing the at least
one current variable (S.sub.ist) to at least one target variable
(S.sub.soll) for calculating at least one correction variable (k),
wherein the target variable (S.sub.soll) is represented by
predefined values regarding the location and orientation of the
light-emitting surfaces (3a, 3b, 3c) with respect to the reference
point; d) populating the circuit carrier (2) with the at least one
electronic component (1) according to the at least one correction
variable (k).
2. The method of claim 1, wherein the current variable (S.sub.ist)
and the target variable (S.sub.soll) are supplied to, or detected
by, a digital computation unit in which the correction variable (k)
is calculated, wherein the correction variable (k) is transferred
to a population device as a digital information signal for
population according to step d).
3. The method of claim 1, wherein the correction variable (k)
comprises at least one vector variable, wherein the direction of
the vector variable is oriented in parallel to the population
surface of the circuit carrier (2).
4. The method of claim 3, wherein the correction variable (k) also
comprises an angular value for rotation about an axis of rotation
(z), wherein the axis of rotation is oriented orthogonally to the
population surface of the circuit carrier (2).
5. The method of claim 1, wherein the at least one current variable
(S.sub.ist) comprises information characterizing the profile, in
particular the slope, of the visible edges of the light-emitting
surfaces (3a, 3b, 3c).
6. The method of claim 1, wherein the at least one current variable
(S.sub.ist) comprises information characterizing a virtual centroid
(S.sub.g) of the light-emitting surfaces (3a, 3b, 3c), wherein the
virtual centroid (S.sub.g) is determined by determining the
geometric centers (S.sub.1, S.sub.2, S.sub.2) of the individual
light-emitting surfaces (3a, 3b, 3c) by taking into account their
current positions.
7. The method of claim 1, wherein the at least one current variable
(S.sub.ist) comprises information characterizing the dimensions and
position of a fictitious rectangular surface, wherein the
dimensions as well as the position and orientation of the
fictitious rectangle (R) are selected such that the ratio between
overlap and size of the surface is optimized.
8. The method of claim 1, wherein the target variable (S.sub.soll)
comprises a position information with respect to a reference point,
wherein the reference point is disposed on the electronic component
(1) or the circuit carrier (2) of the electronic component (1).
9. The method of claim 1, wherein the light-emitting surfaces (3a,
3b, 3c) are spaced from one another.
10. The method of claim 1, wherein the at least one electronic
component (1) has a plurality of at least three, four or five
light-emitting surfaces (3a, 3b, 3c) which are preferably disposed
in a row.
11. The method of claim 1, wherein the electronic component (1) is
an LED, preferably an SMD-LED.
12. The method of claim 1, wherein the light-emitting surfaces (3a,
3b, 3c) are illuminated by an external light source during step
a).
13. The method of claim 1, wherein the light-emitting surfaces (3a,
3b, 3c) are excited to emit light during step a).
14. A circuit carrier (2) with at least one electronic component
(1), wherein the electronic component (1) has at least two
separately controllable light-emitting surfaces (3a, 3b, 3c),
wherein populating the circuit carrier (2) with the at least one
electronic component (1) according to the current positions of the
at least two light-emitting surfaces (3a, 3b, 3c) of the electronic
component (1) is performed according to the method of claim 1.
15. A motor vehicle headlamp with a circuit carrier (2) of claim
14.
Description
[0001] The invention relates to a method for accurate population of
a circuit carrier with at least one electronic component which
comprises at least two separately controllable light-emitting
surfaces.
[0002] Furthermore, the invention relates to a circuit carrier with
at least one electronic component, wherein the electronic component
comprises at least two separately controllable light-emitting
surfaces. Moreover, the invention relates to a motor vehicle
headlamp having a circuit carrier according to the invention.
[0003] Methods for accurate population of a circuit carrier with
electronic components, each having exactly one light-emitting
surface, have been known in the art.
[0004] Various developments in light technology now allow
electronic components to be provided with at least two separately
controllable light-emitting surfaces. For example, such a component
may be the LED light source commercially available under the name
"OSLON Black Flat" (KW H3L531.TE model) from the manufacturer
OSRAM. This allows to considerably reduce the number of electronic
components to be disposed on a circuit carrier, which components
may be intended for use in an LED matrix headlamp, for example.
[0005] In the assembly of such elements using known methods, the
presence of at least two separately controllable light-emitting
surfaces on one single electronic component poses the problem that
a prerequisite of this method--i.e. that each electronic component
has exactly one light-emitting surface--is not satisfied.
Therefore, in order to use said methods, one of the at least two
light-emitting surfaces would first have to be selected according
to criteria to be defined which are not yet known. However, the
remaining light-emitting surfaces would be disregarded in this
case. As such, if a circuit carrier is populated with electronic
components having at least two light-emitting surfaces in a
conventional manner, then an optimum orientation of the components
and/or light-emitting surfaces cannot be ensured. However, errors
in the orientation/position of the light-emitting surfaces can, in
particular when used in a motor vehicle headlamp, lead to
inadmissible inaccuracies and aberrations in the light pattern of
the motor vehicle headlamp.
[0006] One objective of the invention is therefore to provide a
method for accurate population of a circuit carrier with at least
one electronic component which comprises at least two separately
controllable light-emitting surfaces.
[0007] This objective is achieved by a method of the type mentioned
at the beginning, having the following steps according to the
invention: [0008] a) optically detecting current positions of the
at least two light-emitting surfaces of the electronic component,
[0009] b) calculating at least one current variable characterizing
the geometric location of the light-emitting surfaces according to
the current positions of the at least two light-emitting surfaces
of the electronic component, [0010] c) comparing the at least one
current variable to at least one target variable for calculating at
least one correction variable, [0011] d) populating the circuit
carrier with the at least one electronic component according to the
at least one correction variable.
[0012] Thanks to the invention, it is possible to implement an
accurate population of a circuit carrier with at least one
electronic component which comprises at least two separately
controllable light-emitting surfaces, wherein position errors of
two or more light-emitting surfaces on the electronic component can
be detected and compensated for by calculating a correction
variable.
[0013] Optically detecting the current positions of the electronic
component is typically accomplished by using a camera system and
suitable image processing algorithms, wherein the positions are
detected with respect to a reference point which may, for example,
be formed on the electronic component or on the circuit carrier.
Here, the term "(current) position of a surface" not only means the
dimension of the surface, but also its location or spatial
orientation with respect to the reference point.
[0014] The target variable is typically represented by predefined
values regarding the location and orientation of the light-emitting
surfaces with respect to the reference point. For example, the
target variable is determined from the geometric target position
and target dimension of the light-emitting surfaces with respect to
the reference point which may be known from a data sheet, for
example, or can be calculated. Further details can be found in the
description of figures.
[0015] The population under item d) of the method is performed by
taking the correction variable into account in that, with the aid
of the correction variable, a predefined installation position is
corrected into an actual installation position, in which the
electronic component is applied onto, in particular soldered to,
the circuit carrier. The correction variable is determined using a
digital computation unit and can be transferred to a population
device in digital form.
[0016] Thus, it may be contemplated that the current variable
characterizing the geometric location of the light-emitting
surfaces and the target variable are supplied to, or detected by, a
digital computation unit, in which the correction variable is
calculated, wherein the correction variable is transferred to a
population unit for population according to step d) as a digital
information signal.
[0017] Preferably, it may be contemplated that the correction
variable comprises at least one vector variable, the direction of
the vector variable being oriented in parallel to the population
surface of the circuit carrier. Therefore, in a Cartesian
coordinate system, consisting of axes x, y and z which are
orthogonal to one another, in which axes x and y are oriented in
parallel to the population surface of the circuit carrier, the
vector variable contains information on the magnitude and direction
of a vector in the x-y plane. Thus, the population may be corrected
in the x- and y-direction.
[0018] Moreover, it may be advantageous if the correction variable
comprises an angular value for rotation around an axis of rotation
z, wherein the axis of rotation z is oriented orthogonally to the
population surface of the circuit carrier. Thus, it is possible to
change the orientation of the electronic component on the circuit
carrier. As a prerequisite, it is, of course, contemplated that the
target variable will contain information on a target orientation of
the electronic component so that the correction variable can be
calculated by comparing the current variable with the target
variable.
[0019] To detect the orientation of the light-emitting surfaces in
a convenient manner, it may be contemplated that the at least one
current variable contains information characterizing the profile,
in particular the slope, of the visible edges of the light-emitting
surfaces. For example, this information may comprise the position
of a plurality of points on the edge, which are detected by common
edge detection (e.g. by gradient filtering), for example. The
location of the edges is of particular importance when used in
lighting systems in which the edge profile has a direct impact on
the light pattern of the lighting system. For example, this is the
case with a motor vehicle headlamp having a low-beam function where
no additional mask is provided for defining a cut-off line, but
where the cut-off line is, for example, defined by the location of
the light-emitting surfaces with respect to an optical system, e.g.
a reflector. Other light functions for which defined light-dark
transitions are relevant would be exemplified by an adaptive
front-lighting function, a fog light function and an adaptive high
beam.
[0020] Alternatively, it may be contemplated that the at least one
current variable comprises information characterizing a virtual
centroid of the light-emitting surfaces, wherein the virtual
centroid is determined by determining the geometric centers of the
individual light-emitting surfaces by taking into account their
current positions.
[0021] In another version of the invention, it may be contemplated
that the at least one current variable comprises information
characterizing the dimension and position of a fictitious
rectangular surface, wherein the dimensions as well as the position
and orientation of the fictitious rectangle are selected such that
the ratio between overlap and size of the surface is optimized.
[0022] These two latter types of information on the current
variable are well-suited for use in the population of circuit
carriers adapted to produce a high-beam distribution. This is
because the homogeneity of the overall light pattern is of much
greater importance there than the profile of individual edges,
wherein the light patterns of individual light-emitting surfaces
typically overlap each other at least partially so that the profile
of individual edges is less important. In addition, these methods
are well-suited for the population of circuit carriers incorporated
into imaging systems where cut-off lines are formed by additional
aids such as masks.
[0023] More specifically, it may be contemplated that the target
variable comprises position information with respect to a reference
point, wherein the reference point is disposed on the electronic
component or the circuit carrier of the electronic component.
Optically detecting the current position of the light-emitting
surfaces here also includes detecting the reference points such
that the positions can be measured with respect to the reference
points.
[0024] In an advantageous implementation of the invention, the
light-emitting surfaces may be spaced from one another.
Alternatively, the light-emitting surfaces may be disposed on a
single converter surface, wherein different areas of the converter
surface may be controlled and activated by separately controllable
chips.
[0025] More specifically, it may be contemplated that the at least
one electronic component has a plurality of at least three, four or
five light-emitting surfaces which are preferably disposed in a
row.
[0026] It may be particularly advantageous if the electronic
component is an LED, preferably an SMD-LED.
[0027] To be able to optically detect the light-emitting surfaces
more easily, it may be advantageous to illuminate the
light-emitting surface with an external light source during step
a).
[0028] In particular, the light-emitting surfaces may be excited to
emit light during step a). The excitation may either be
accomplished by illumination of sufficient intensity by an external
light source or also by activation of the electronic component.
[0029] In another aspect, the invention relates to a circuit
carrier with at least one electronic component, wherein the
electronic component has at least two separately controllable
light-emitting surfaces, characterized in that population of the
circuit carrier with at least one electronic component according to
the current positions of the at least two light-emitting surfaces
of the electronic component is performed according to the method of
the invention as discussed at the beginning.
[0030] Moreover, the invention relates to a motor vehicle headlamp
with a circuit carrier according to the invention.
[0031] The invention is explained in greater detail below with
reference to an exemplary and non-limiting embodiment illustrated
in the figures. Therein,
[0032] FIG. 1 shows a schematic representation of a fictitious
electronic component on a section of a circuit carrier,
[0033] FIG. 2 shows a representation of the rear of the electronic
component,
[0034] FIGS. 3a and 3b show a representation of a real electronic
component with incorrectly aligned light-emitting surfaces and a
measure to eliminate the error,
[0035] FIGS. 4a and 4b show a representation of the electronic
components of FIG. 3a and another measure to eliminate the
error,
[0036] FIG. 5 shows another electronic component with incorrectly
aligned light-emitting surfaces and another measure to eliminate
the error,
[0037] FIG. 6 shows the electronic component of FIG. 5 and another
measure to eliminate the error.
[0038] FIG. 1 shows a schematic representation of a fictitious
(derived from the data sheet) electronic component 1 on a section
of a circuit carrier 2 which was populated with electronic
component 1 (fictitious). In the present example, electronic
component 1 has three separately controllable light-emitting
surfaces 3a, 3b and 3c. From this fictitious example, a target
variable can be determined in advance against which the optically
determined current variable can be compared during the actual
population process.
[0039] Individual position information relates to the Cartesian
coordinate system, consisting of axes x, y and z, wherein axes x
and y are oriented in parallel to the plane of the light-emitting
surfaces and axis z protrudes into the sheet plane. The choice of
the coordinate system and its location may be freely determined by
one skilled in the art as long as a clear definition of the
location of the light-emitting surfaces 3a, 3b and 3c is possible.
Thus, a Cartesian coordinate system x', y', z' could also be
employed, the origin of which lies in a corner of the housing of
electronic component 1. Such corners may often be detected
particularly easily by optical detection methods and downstream
image processing algorithms. The origin of the selected coordinate
system constitutes the reference point for position
information.
[0040] In the exemplary embodiment shown, the light-emitting
surfaces 3a, 3b und 3c have a square shape with a side length 1.
They are disposed in a row and spaced from one another. The
exemplified electronic component 1 is the model of the "OSLON Black
Flat" series mentioned at the beginning, wherein the housing of the
electronic component has a side length sl in the x- and y-direction
of between 2 and 10 mm and the width b of the row of light-emitting
surfaces 3a, 3b und 3c is between approximately 1.5 and 9 mm.
[0041] The light-emitting surfaces 3a, 3b und 3c each have centers
or centroids S.sub.1, S.sub.2 and S.sub.3, wherein these are offset
with respect to the zero point of the coordinate system x, y, z.
Thus, all three centroids S.sub.1, S.sub.2 and S.sub.3 have an
offset y1 (e.g. between 0.1 and 0.6 mm, these values are derived
from the data sheet) in the direction of the y-axis. In addition,
centroids S.sub.1 and S.sub.3 are offset towards/in x-direction
relative to the zero point of the coordinate system x, y and z.
From the location of the individual light-emitting surfaces 3a, 3b
and 3c and/or the centroids S.sub.1, S.sub.2 and S.sub.3, an
overall centroid S.sub.g (referred to as a virtual centroid in the
claims) can be calculated which coincides with the target centroid
S.sub.soll--as the data of electronic component 1, as shown,
corresponds to the target values (without tolerances). This target
centroid S.sub.soll can be used as the target variable in the
method according to the invention.
[0042] FIG. 2 shows a representation of the rear of electronic
component 1, wherein the contact surfaces of anodes A1 to A3 and
cathodes K1 to K3 are shown therein, which are associated with
individual chips, preferably LED chips, configured to control
light-emitting surfaces 3a, 3b and 3c. After population of circuit
carrier 2 with electronic component 1, sufficient contact must be
established between the cathode and anode surfaces and
corresponding surfaces on the circuit carrier. For this purpose,
the contact surfaces may, for example, be coated, in particular
printed, with solder paste and secured to electronic component 1 in
a reflow soldering process.
[0043] FIGS. 3a and 3b show a representation of a real electronic
component 1 where light-emitting surfaces 3a, 3b and 3c are not
disposed in the target positions derived from the data sheet
(indicated by dashed surfaces 3a', 3b' and 3c'), but exhibit
deviations therefrom. Light-emitting surfaces 3a, 3b and 3c all
have an offset in the direction of the y-axis. Moreover, the first
light-emitting surface 3a is offset outwardly against the direction
of the x-axis. In contrast to electronic component 1 in accordance
with the data sheet (see FIG. 1), the individual centroids S.sub.1,
S.sub.2 und S.sub.3 of light-emitting surfaces 3a, 3b and 3c are no
longer disposed on a common line. FIG. 3a now shows a way to
determine a current variable (in this example a position)
associated with the offset light-emitting surfaces 3a, 3b and 3c,
which may be compared with a target variable S.sub.soll, i.e. the
desired location of the overall centroid.
[0044] For this purpose, a self-contained geometric shape is
defined, the corner points of which are formed by the centroids of
the individual light-emitting surfaces. In this example, centroids
S.sub.1, S.sub.2 and S.sub.3 form a triangle which is shown
schematically. The centroid of this triangle may either be
determined geometrically by the medians indicated in FIG. 3a or
mathematically and corresponds to the overall centroid of
light-emitting surfaces 3a, 3b and 3c and can be used as current
variable S.sub.ist. According to step c) of the method of the
invention, current variable S.sub.ist can now be compared to target
variable S.sub.soll to determine a correction variable therefrom.
In this example, the target variable contains coordinates on the x-
and y-position of the overall target centroid and the current
variable contains coordinates on the x- and y-position of the
overall current centroid. By obtaining the difference between the
coordinates of S.sub.soll and S.sub.ist, the correction variable k
may be calculated in the form of a vector which can be used to
correct the population position of electronic component 1 on
circuit carrier 2.
[0045] This process is exemplified in FIG. 3a, in which a
predefined population position, position P1, has been corrected
into an actual population position P2 by displacing the electronic
component by a vector of correction variable k such that the
position of the corrected overall centroid S.sub.ist,korr is
consistent with position S.sub.soll. This process corresponds to
step d) of the method according to the invention.
[0046] The examples according to FIGS. 4a, 4b, 5 and 6 address
other and, where appropriate, alternative aspects of the invention
and illustrate that the method of the invention is widely
applicable and not limited to the version according to FIGS. 3a and
3b.
[0047] Thus, FIG. 4a shows electronic component 1 according to FIG.
3a, wherein another way to correct the location of light-emitting
surfaces 3a, 3b and 3c is illustrated. Here, a regression line is
placed between the individual centroids S.sub.1, S.sub.2 and
S.sub.3, wherein the slope .alpha. of the regression line is
assessed with respect to the x-axis (or y-axis) and the position of
electronic component 1 according to FIG. 4b is corrected by
displacing electronic component 1 according to FIG. 3b and
additionally rotating it about the z-axis by an angle .alpha.. In
this example, correction variable k therefore comprises both a
vector variable, comprising the coordinates of the displacement in
the x- and y-direction, and an angular value, i.e. angle .alpha.,
indicating a rotation about axis z.
[0048] FIG. 5 shows another real electronic component 1 with
incorrectly disposed light-emitting surfaces 3a, 3b and 3c and
another measure to eliminate the error. Here, edges e1, e2 and e3
of light-emitting surfaces 3a, 3b und 3c are optically detected,
for which purpose the location of at least two points on edges e1,
e2 and e3 must be established. The location and profile of the
edges can be determined such that, similar to the method according
to FIGS. 4a and 4b, a regression line can be calculated, the slope
.alpha. of which can be used to correct the actual population
position of electronic component 1. The correction of the
orientation of edges e1, e2 and e3 of light-emitting surfaces 3a,
3b und 3c is primarily relevant for motor vehicle headlamp modules
where the individual light sources are reproduced sharply in the
light pattern of the headlamp, as is the case with maintaining
cut-off lines for low beam, adaptive high beam, adaptive
front-lighting and fog light modules, for example, in which the
low-beam distribution is defined by the location of the light
sources with respect to and in relation to a reflector.
[0049] FIG. 6 shows another measure for electronic component 1
according to FIG. 5 to eliminate the incorrect position of
light-emitting surfaces 3a, 3b and 3c. For this purpose, current
variable S.sub.ist comprises information characterizing the
dimensions and position of a fictitious rectangular surface R,
wherein the dimensions as well as the position and orientation of
the fictitious rectangle R are selected such that the ratio between
overlap and size of the surface is optimized. In a most simple
version of this method, it may be contemplated that rectangle R is
determined based on the positions and dimensions of light-emitting
surfaces 3a, 3b and 3c of electronic component 1 according to FIG.
1 and the rectangle R thus obtained is positioned and oriented such
that the surface overlap with light-emitting surfaces 3a, 3b and 3c
is at a maximum. In turn, the location of the centroid and the
orientation of rectangle R can be used to correct the population
position of electronic component 1.
[0050] The term "characterizing information" often used in the
claims merely means that suitable variables or fields are used to
identify the relevant information which are suitable to reflect and
clearly define the relevant information. For example, information
characterizing the position and orientation of fictitious
rectangular surface R may be indicated by a field in which entries
on the length, width, position and orientation of rectangle R are
indicated.
[0051] The improvement of the location of overall centroid S.sub.g
of light-emitting surfaces 3a, 3b and 3c is particularly relevant
for high-beam functions or for all other functions where cut-off
lines are defined using additional aids such as masks.
[0052] The exemplary embodiments shown in FIGS. 1 to 6 disclose an
electronic component 1 with three light-emitting surfaces 3a, 3b
and 3c. It is understood that the number of light-emitting surfaces
may deviate from the number shown. Similarly, the geometric shape
of the light-emitting surfaces may deviate from the shapes
shown.
[0053] To recognize light-emitting surfaces 3a, 3b and 3c more
easily, it may be contemplated that they are illuminated by an
external light source during step a), by which the contrast of
light-emitting surfaces 3a, 3b and 3c to surrounding surfaces can
be improved. This external light source preferably emits blue light
onto light-emitting surfaces 3a, 3b and 3c. Depending on whether a
quick optical detection is critical (e.g. for rapid population), it
may be contemplated that the wavelength and intensity of the light
emitted by the external light source are selected such that
light-emitting surfaces 3a, 3b and 3c are excited to emit
light.
[0054] In view of this teaching, one skilled in the art is able to
obtain other embodiments of the invention which are not shown.
Hence, the invention is not limited to the embodiments shown.
Moreover, individual aspects of the invention or the embodiments
may be taken up and combined with one another. What is essential
are the ideas underlying the invention which may be implemented by
one skilled in the art in multiple ways having regard to this
description and still be maintained as such.
* * * * *