Coin discriminator using a plurality of optical fiber groups

A coin discriminating apparatus including a light source for irradiating the surface of a coin to be discriminated with light normal thereto, a plurality of optical fiber groups each including a plurality of optical fibers for guiding light reflected by the surface of the coin to be discriminated, each of the optical fibers disposed so that an imaginary extension of the center axis thereof passes through the center of the surface of the coin to be discriminated at a predetermined angle, the predetermined angle being different between different optical fiber groups, a plurality of photoelectric converters each facing an end portion of an associated one of the optical fiber groups further from the end portion facing the coin to be discriminated and being adapted for receiving the reflected light guided by the associated optical fiber group and converting it to an electrical signal proportional to the amount of the received light, and a discriminator for discriminating coins based upon the electrical signals generated by the plurality of photoelectric converters. The thus constituted apparatus can, with a simple structure, discriminate the denominations, genuineness and the like of coins by detecting coin surface unevenness.

BACKGROUND OF THE INVENTION 
The present invention relates to a coin discriminating apparatus and, in 
particular, to such a apparatus which can detect coin surface unevenness 
and based thereon discriminate the denominations, genuineness and the like 
of coins with a simple structure. 
DESCRIPTION OF PRIOR ART 
There has been known a method for detecting coin surface unevenness by 
irradiating the surface of a coin, detecting light reflected by the 
surface of the coin and based upon this detection, discriminating the 
denomination, genuineness and the like of the coin. 
For instance, Japanese Patent Publication No. Hei 3-63782 proposes a coin 
discriminating apparatus for discriminating the genuineness of coins by 
obliquely irradiating the surface of each coin and comparing data obtained 
by detecting light reflected by arcuate portions in a plurality of annular 
areas concentric with the center of the coin with reference data 
determined in advance. 
Since this apparatus discriminates the genuineness of coins by detecting 
the unevenness of characteristic surface portions of each denomination of 
coin based upon light reflected from the coins, it is able to accurately 
discriminate coins. 
However, in the case of discriminating foreign coins from predetermined 
coins of the same diameter, it is unnecessary to discriminate coins by 
detecting the unevenness of surface characteristic portions of each 
denomination of coin as done in the prior art apparatus. In this case, the 
structure of the prior art coin discriminating apparatus is unnecessarily 
complicated. 
SUMMARY OF THE INVENTION 
It is, therefore, an object of the present invention to provide a coin 
discriminating apparatus which can detect coin surface unevenness and 
based thereon discriminate the denominations, genuineness and the like of 
coins with a simple structure. 
The above and other objects of the present invention can be accomplished by 
a coin discriminating apparatus comprising irradiating means for 
irradiating the surface of a coin to be discriminated with light normal 
thereto, a plurality of optical fiber groups each including a plurality of 
optical fibers for guiding light reflected by the surface of the coin to 
be discriminated, each of the optical fibers having a light receiving end 
portion disposed so that an imaginary extension of the center axis thereof 
passes through the center of the surface of the coin to be discriminated 
at a predetermined angle, said predetermined angle being different between 
different optical fiber groups, a plurality of photoelectric converting 
means each facing the end portion of an associated one of optical fiber 
groups further from the light receiving end portion facing the coin to be 
discriminated and being adapted for receiving the reflected light guided 
by the associated optical fiber groups and converting it to an electrical 
signal proportional to the amount of the received light, and 
discriminating means for discriminating coins based upon the electrical 
signals generated by the plurality of photoelectric converting means. 
In a preferred aspect of the present invention, the light receiving end 
portions of the plurality of optical fibers are spaced by the same 
distance from the center of the coin to be discriminated. 
In a further preferred aspect of the present invention, the discriminating 
means includes calculating means for producing detection data based upon 
the electrical signals and comparing means for comparing the detection 
data with reference data stored therein. 
In a further preferred aspect of the present invention, the light receiving 
end portions of the plurality of optical fibers of each of the optical 
fiber groups are disposed to be concentric with the center of the coin to 
be discriminated. 
In a still further preferred aspect of the present invention, the light 
receiving end portions of the plurality of optical fibers are supported by 
support means formed as a hemispherical shell. 
In another preferred aspect of the present invention, the discriminating 
means includes amplifier means or amplifying the electrical signals.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A coin discriminating apparatus which is an embodiment of the present 
invention is constituted so as to discriminate foreign coins from 
predetermined coins which foreign and predetermined coins cannot be 
discriminated from each other based upon difference in diameter 
therebetween. In FIG. 1, the coin discriminating apparatus comprises a 
light source 1, a collimator lens 3 for converting light emitted from the 
light source 1 to a parallel light flux 2 and a casing 4 formed as a 
hemispherical shell and having the top portion of the casing 4 thereof 
formed with a circular opening 5 the diameter of which is slightly smaller 
than that of coins to be discriminated. 
Therefore, light emitted from the light source 1 is converted to a parallel 
light flux 2 by the collimator lens 3 and projected onto a coin 6 which 
has been transported to the coin discriminating apparatus by a 
transporting means (not shown) so that the center thereof is aligned with 
the center of the casing 4 constituted as the hemispherical shell. 
The light receiving end portions of three optical fiber groups A, B, C are 
mounted on the casing 4. Each group of optical fibers A, B, C comprises N 
number of optical fibers A(1) to A(N), B(1) to B(N) and C(1) to C(N). The 
number N is a positive integer. As shown in FIG. 2, the optical fibers 
A(1) to A(N) constituting the optical fiber group A are disposed such that 
the angle between the imaginary extensions of the center axes of the light 
receiving end portions of the optical fibers A(1) to A(N) and the center 
axis L of the casing 4, namely, the imaginary extension of the center axis 
passing through the center of the coin to be discriminated is equal to 
"a". The optical fibers B(1) to B(N) constituting the optical fiber group 
B is disposed such that the angle between the center axes of the light 
receiving end portions of the optical fibers B(1) to B(N) and the center 
axis of the casing 4 is equal to "b". The optical fibers C(1) to C(N) 
constituting the optical fiber group C is disposed such that the angle 
between the center axes of the light receiving end portions of the optical 
fibers C(1) to C(N) and the center axis of the casing 4 is equal to "c". 
The light receiving end portions of the optical fibers A(1) to A(N) are 
disposed in the vicinity of the opening 5 of the casing 4 and a&lt;b&lt;c. The 
light receiving end portions of the optical fibers A(1) to A(N) are 
equally spaced from each other along a circle on the surface of the casing 
4 concentric with the center axis of the casing 4. The light receiving end 
portions of the optical fibers B(1) to B(N) are equally spaced from each 
other along a circle on the surface of the casing 4 concentric with the 
center axis of the casing 4. The light receiving end portions of the 
optical fibers C(1) to C(N) are equally spaced from each other along a 
circle on the surface of the casing 4 concentric with the center axis of 
the casing 4. 
In this embodiment, the number N is set to be even and, therefore, as shown 
in FIG. 2, the optical fibers A(i) and A(N/2+i), the optical fibers B(i) 
and B(N/2+i) and the optical fibers C(i) and C(N/2+i) are symmetrically 
disposed with respect to the center axis L of the casing 4. The number "i" 
is a positive integer equal to or smaller than "N/2". 
FIG. 3 is a schematic front view showing the optical fibers A(1) to A(N), 
B(1) to B(N), C(1) to C(N) and a one dimensional image sensor. 
In FIG. 3, the end portions of the optical fibers A(1) to A(N) further from 
the coin 6 are disposed to face a pixel row 7A consisting of N pixels of 
the one dimensional image sensor 7 so that light from each optical fiber 
is received by only one pixel among them. The end portions of the optical 
fibers B(1) to B(N) further from the coin 6 are disposed to face a pixel 
row 7B consisting of N pixels of the one dimensional image sensor 7 
different from the pixel row 7A so that light from each optical fiber is 
received by only one pixel among them. The end portions of the optical 
fibers C(1) to C(N) further from the coin 6 are disposed to face a pixel 
row 7C consisting of N pixels of the one dimensional image sensor 7 
different from the pixel rows 7A and 7B so that light from each optical 
fiber is received by only one pixel among them. 
FIG. 4 is a block diagram of a detection system, a discriminating system 
and a display system of the coin discriminating apparatus which is an 
embodiment of the present invention. 
In FIG. 4, when a pixel row 7A, 7B, 7C of the one dimensional image sensor 
7 receives light reflected by the coin 6, it converts the light to an 
electrical detection signal and outputs the signal to a discriminating 
means 8. The discriminating means 8 comprises a calculating means 9 for 
integrating the detection signals input from the pixel rows 7A, 7B, 7C and 
calculating the gradient of a detection data curve obtained by plotting 
the integrated values with respect to the positions of the optical fibers 
A(1) to A(N), B(1) to B(N), C(1) to C(N) and a comparing means 10 for 
comparing the gradient of the detection data curve calculated by the 
calculating means 9 with a reference gradient stored therein in advance to 
discriminate whether the coin 6 is a predetermined coin or a foreign coin 
and outputting a display signal to a display means 11 when it judges that 
the coin 6 is a foreign coin. When the display means 11 receives the 
display signal, it displays on a display portion (not shown) a message 
that a foreign coin has been detected. 
The thus constituted coin discriminating apparatus which is an embodiment 
of the present invention operates as follows to discriminate coins. 
At first, when a coin 6 has been transported to the coin discriminating 
apparatus by a transporting means (not shown) and it is detected that the 
center of the coin 6 coincides with the center of the casing 4 formed as a 
hemispherical shell, the light source 1 emits light. The light emitted 
from the light source 1 is converted to a parallel light flux 2 by the 
collimator lens 3 and projected onto the surface of the coin 6 normal 
thereto. 
The light projected onto the surface of the coin 6 to be discriminated is 
reflected by the surface of the coin 6 and received by the light receiving 
end portions of the optical fibers A(1) to A(N), B(1) to B(N), C(1) to 
C(N). The light projected onto the surface of the coin 6 normal thereto is 
reflected by the flat surface of coin 6 normal thereto, whereas the light 
is reflected by uneven portions of the surface of coin 6 in oblique 
directions depending upon the angles of the surfaces of the uneven 
portions with respect to the horizontal plane. 
Accordingly, the more uneven portions that are present on the surface of 
coin 6, the greater the ratio of light reflected in oblique directions 
becomes, whereby the amount of reflected light received by the optical 
fibers A(1) to A(N) constituting the optical fiber group A decreases and 
an amount of reflected light received by the optical fibers B(1) to B(N) 
constituting the optical fiber group B and the optical fibers C(1) to C(N) 
constituting the optical fiber group C increases. On the other hand, the 
fewer uneven portions that are present on the surface of coin 6, the more 
the optical fibers A(1) to A(N) constituting the optical fiber group A 
receive reflected light, whereby the amount of reflected light received by 
the optical fibers B(1) to B(N) constituting the optical fiber group B and 
the optical fibers C(1) to C(N) constituting the optical fiber group C 
decreases. 
Each of the pixel rows 7A, 7B, 7C of the one dimensional image sensor 7 
converts received light to an electrical detection signal the magnitude of 
which depends upon the amount of received light and outputs it to the 
discriminating means 8. 
The calculating means 9 of the discriminating means 8 integrates the 
detection signals input from the pixel rows 7A, 7B, 7C of the one 
dimensional image sensor 7 and plots the integrated values with respect to 
the angles between the center axes of the optical fibers A(1) to A(N), 
B(1) to B(N) and C(1) to C(N) and the center axis L of the casing 4, 
thereby producing a detection data curve and calculates the gradient of 
the detection data curve for output to the comparing means 10. The greater 
the angle an uneven surface portion formed on the coin 6 makes with 
respect to the horizontal plane, the greater the amount of reflected light 
received by the optical fibers C(1) to C(N) constituting the optical fiber 
group C becomes and the smaller the angle an uneven surface portion on the 
coin 6 makes with respect to the horizontal plane, the greater the amount 
of reflected light received by the optical fibers B(1) to B(N) 
constituting the optical fiber group B becomes. However, since the angles 
of uneven surface portions formed on the surface of coin 6 are normally 
not great, the more uneven portions that are present on the surface of the 
coin 6, the greater the amount of reflected light received by the optical 
fibers C(1) to C(N) becomes, but the increase in the amount of reflected 
light received by the optical fibers B(1) to B(N) is greater than the 
increase in the amount received by the optical fibers C(1) to C(N). 
Therefore, the more uneven portions that are present on the surface of the 
coin 6, the smaller the gradient of the detection data curve becomes. 
The comparing means 10 compares the gradient of the detection data curve 
input from the calculating means 9 with a reference gradient stored 
therein in advance to discriminate whether the coin 6 is a predetermined 
coin or a foreign coin. 
When the comparing means 10 judges that the coin 6 is a foreign coin, it 
outputs a display signal to the display means 11 so as to cause it to 
display on a display portion (not shown) a message that a foreign coin has 
been detected. 
FIGS. 5 (a) and (b) show examples of detection data curves obtained by 
plotting integrated values of the amounts of reflected light received by 
the pixel rows 7A, 7B, 7C calculated by the calculating means 9 with 
respect to angles between the center axes of the optical fibers A(1) to 
A(N), B(1) to B(N) and C(1) to C(N) and the center axis L of the casing 4. 
FIG. 5 (a) shows an example of a detection data curve obtained from a coin 
6 on which many uneven portions are present and FIG. 5 (b) shows an 
example of a detection data curve obtained from a coin 6 on which not so 
many uneven portions are present. 
As apparent from FIGS. 5 (a) and (b), since the amount of reflected light 
received by the optical fibers B(1) to B(N) and C(1) to C(N) becomes 
greater in the case where many uneven portions are present on the surface 
of the coin 6 than in the case where not so many uneven portions are 
present on the surface of the coin 6, the gradient of the detection data 
curve becomes smaller. Therefore, by comparing the gradient of the 
detection data curve with the reference gradient it is possible to 
discriminate whether the coin 6 is the predetermined coin or a foreign 
coin. 
According to this embodiment, it is possible to discriminate whether the 
coin 6 is a predetermined coin or a foreign coin only by locating the 
light receiving end portions of the optical fibers A(1) to A(N), B(1) to 
B(N) and C(1) to C(N) at their predetermined positions, respectively 
integrating the amounts of reflected light received thereby, calculating 
the gradient of the detection data curve obtained by plotting the 
integrated values with respect to the angles between the center axes of 
the optical fibers A(1) to A(N), B(1) to B(N) and C(1) to C(N) and the 
center axis L of the casing 4 formed as a hemispherical shell and 
comparing the thus calculated gradient with the reference gradient. 
Therefore, it is possible to discriminate coins by a coin discriminating 
apparatus with a simple structure. 
FIG. 6 is a schematic center lateral cross sectional view showing a coin 
discriminating apparatus which is another embodiment of the present 
invention. 
The coin discriminating apparatus shown in FIG. 6 has the same 
configuration as that in the previous embodiment except that the shape of 
the casing 4 is different. More specifically, although the previous 
embodiment is provided with the casing 4 formed as a hemispherical shell, 
the casing 4 of the coin discriminating apparatus according to this 
embodiment is constituted as a shell having four wall portions the angles 
of which are different from each other. Light receiving end portions of N 
optical fibers A(1) to A(N) are mounted on wall portion 4A. Light 
receiving end portions of N optical fibers B(1) to B(N) are mounted on 
wall portion 4B. Light receiving end portions of N optical fibers C(1) to 
C(N) are mounted on wall portion 4C. Each light receiving end portion of 
the optical fibers is oriented so that the extension of its center axis 
passes through the center of the shell constituting the casing 4, namely 
the center of the coin 6. 
Similarly to the previous embodiment, the more uneven portions that are 
present on the surface of the coin 6, the greater the amount of reflected 
light received by the optical fibers B(1) to B(N) and C(1) to C(N), 
whereby it is possible to discriminate whether the coin 6 is a 
predetermined coin or a foreign coin by calculating the gradient of the 
detection data curve and comparing it with the reference gradient. 
However, in this embodiment, the distance between the light receiving end 
portions of the optical fibers A(1) to A(N) and the surface of the coin 6, 
the distance between the light receiving end portions of the optical 
fibers B(1) to B(N) and the surface of the coin 6 and the distance between 
the light receiving end portions of the optical fibers A(1) to A(N) and 
the surface of the coin 6 are different from each other, as shown in FIG. 
7. Therefore, the discriminating means 8 includes amplifier means 12a, 12b 
each having a predetermined amplifying factor for correcting the detection 
signals output from the pixel rows 7A, 7B in proportion to the distances 
between the optical fibers and the surface of the coin 6 and outputting 
corrected detection signals to the calculating means 9. 
The present invention has thus been shown and described with reference to a 
specific embodiment. However, it should be noted that the present 
invention is in no way limited to the details of the described 
arrangements but changes and modifications may be made without departing 
from the scope of the appended claims. 
For example, in the above described embodiments, although the optical fiber 
group A is constituted by N optical fibers A(1) to A(N), the optical fiber 
group B is constituted by N optical fibers B(1) to B(N) and the optical 
fiber group C is constituted by N optical fibers C(1) to C(N) wherein N is 
determined to be an even number, N may instead be an odd number. Further, 
although the respective optical fiber groups A, B, C are constituted by 
the same number of optical fibers and the three optical fiber groups A, B, 
C are mounted on the casing 4 so as to be concentric with the center axis 
of the casing 4, if amplifier means are provided for correcting the 
detection signals output from the pixel rows 7A, 7B, 7C, the numbers of 
the optical fibers constituting the optical fiber groups A, B, C may be 
different and it is unnecessary to dispose the optical fiber groups A, B, 
C so as to be concentric with the center axis of the casing 4. 
Moreover, in the above described embodiments, although an electrical signal 
proportional to the amount of reflected light from the coin 6 is generated 
using the pixel rows 7A, 7B, 7C of the one dimensional image sensor 7, it 
is possible to use a photoelectric converting element such as CCD (charge 
coupled device), a photodiode or the like which can generate electrical 
signals in proportion to the amount of reflected light received by the 
optical fibers A(1) to A(N), B(1) to B(N) and C(1) to C(N), instead of the 
one dimensional image sensor 7. 
Further, in the above described embodiments, although a hemispherical shell 
or a shell having four wall portions whose angles are different from each 
other is used as the casing 4, the shape of the casing 4 is not limited 
and any casing may be used insofar as it can fix the light receiving end 
portions of the optical fibers A(1) to A(N), B(1) to B(N) and C(1) to C(N) 
such that imaginary extensions of the center axes thereof pass through the 
center of the coin 6 to be discriminated. 
Furthermore, in the above described embodiments, although the 
discrimination of coins is made by comparing the gradient of the detection 
data curve with the reference curve, it is possible to discriminate coins 
by producing reference data in advance, storing them in the comparing 
means 10 and comparing the reference data and the detection data. In this 
case, even if no amplifier means is provided, it is possible to set the 
distances between the light receiving end portions of the optical fibers 
A(1) to A(N), B(1) to B(N) and C(1) to C(N) and the surface of the coin 6 
to be discriminated so as to be different from each other and it is 
unnecessary to dispose the light receiving end portions of the optical 
fibers A(1) to A(N), B(1) to B(N) or C(1) to C(N) so as to be equally 
spaced from each other. 
Moreover, in the above described embodiments, although it is discriminated 
by comparing the gradient of the detection data curve with the reference 
gradient whether or not the coin 6 is a predetermined coin or a foreign 
coin, it is possible to discriminate the damage level of the coin 6 in 
addition to such discrimination by storing a reference amount of reflected 
light to be received by one of the optical fiber groups A, B or C in the 
comparing means 10 and comparing the amount of reflected light received by 
the one of the optical fiber groups A, B or C with the reference amount 
based upon the detection signal, or comparing the detection data with the 
reference data. FIG. 8 shows the detection data curve of a damaged coin 
produced according to the embodiment shown in FIGS. 1 to 5. Since the 
entire surface of a damaged coin is normally uniformly damaged, the amount 
of reflected light received by the optical fiber groups A, B, C is 
uniformly decreased and the detection data curve, which is normally as 
shown by the dotted line, becomes as shown by the solid line. Therefore, 
it is possible to further discriminate the damage level of coin 6 by 
calculating the gradient of the detection data curve based upon the 
detection signals from the one dimensional image sensor 7 and comparing 
the amount of reflected light received by one of the optical fiber groups 
A, B, C with the reference amount stored in the comparing means 10 in 
advance. 
Further, in the above described embodiments, although light emitted from 
the light source 1 is converted to a parallel light flux 2 using the 
collimator lens 3, it is possible to provide a parallel light flux 2 onto 
the coin 6 using a laser source for emitting a laser beam having a high 
rectilinear propagation ability, instead of the light source 1 and the 
collimator lens 3. 
Furthermore, in the above described embodiments, although three optical 
fiber groups A, B, C are used, this is not absolutely necessary and any 
number of optical fiber groups greater the one suffices. 
Moreover, in the present invention, the respective means need not 
necessarily be physical means and arrangements whereby the functions of 
the respective means are accomplished by software fall within the scope of 
the present invention. In addition, the function of a single means may be 
accomplished by two or more physical means and the functions of two or 
more means may be accomplished by a single physical means. 
According to the present invention, it is possible to provide a coin 
discriminating apparatus which can detect coin surface unevenness and 
based thereon discriminate the denominations, genuineness and the like of 
coins with a simple structure.