Apparatus for detecting the thickness of bank note

An apparatus for detecting the thickness of a bank note has a plurality of detectors which slide along the surface of the bank note. The detectors are attached to a detection arm side by side. The detection arm is pivotably mounted an a machine frame. If one or more detectors slide on the bank note having a thickness exceeding a standard value, the arm is swung and the displacement of the arm is detected.

BACKGROUND OF THE INVENTION 
This invention relates to an apparatus which is installed in an automatic 
money exchange machine and which detects the thickness of a bank note. 
Heretofore, the determination of the genuineness of a bank note deposited 
in an automatic money exchange machine, or the like, has been mainly 
carried out by reading the pattern of a portion of the bank note and 
collating the read-out pattern with reference data. If a system of reading 
only the pattern of one portion of a bank note is adopted, however it 
cannot be categorically said that there is no possibility of a fabricated 
bank note, such as one made by cutting a bank note into slender strips and 
connecting some of them by using adhesive tape (see FIG. 9), being 
erroneously recognized and accepted as a genuine one. 
To detect such a fabricated bank note, devices such as an "Apparatus for 
Detecting the Thickness of Paper and the Like" disclosed in the 
publication of Japanese Patent Public Disclosure No. 60592/1984 have been 
proposed. 
This detection apparatus adopts a system in which, as shown in FIGS. 7 and 
8, a planar detection arm 4 which is vertically rotatable about a shaft 3 
as center is made to come into contact with a bank note 2 being 
transported on rolls 1, and the angle of rotation of the shaft 3 caused by 
the vertical movement of the detection arm 4 in accordance with the 
thickness of the bank note 2 is detected by a potentiometer 5. This 
detection apparatus is designed so that it can detect the change in an 
output signal from the potentiometer 5 when the detection arm 4 rotates 
(in the clockwise direction as viewed in FIG. 7) when a piece of adhesive 
tape (with a thickness of approximately 0.03 mm) which is thinner than the 
bank note 2 (with a thickness of about 0.09 mm) passes below the detection 
arm 4, thereby enabling the rejection of a fabricated bank note. 
However, the detection apparatus of the above-described method is capable 
of detecting a fabricated bank note only when a piece of adhesive tape 6 
passes below the detection arm 4, as shown in FIG. 9. Therefore, it is 
possible that such a detection apparatus will be incapable of detecting a 
fabricated bank note when a bank note strip 7 of a narrow width passes 
below the detection arm 4. 
Accordingly, it is conceivable to provide a plurality of detection 
apparatuses, each constituted by a detection arm 4 and a potentiometer 5. 
However, this arrangement has the problem that it increases the cost of 
the apparatus. 
SUMMARY OF THE INVENTION 
It is, therefore, an object of the invention to provide, at a low cost, a 
thickness-detecting apparatus which is capable of positively detecting a 
fabricated bank note made by connecting a relatively small number of 
narrow strips of a bank note by means of adhesive tape. 
To attain the aforementioned object, it has been noted that the joint 
portion where a bank note strip and a piece of adhesive tape overlap is 
thicker than a real bank note, so that the genuineness of a bank note can 
be determined by detecting whether any one of a plurality of detectors 
sliding along the surface of a bank note has been displaced by such a 
thicker portion.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
One embodiment of the present invention will be now described in detail 
with reference to the accompanying drawings. 
FIG. 4 shows the external appearance of an automatic money exchange machine 
to which the detection apparatus of the present invention is applied. This 
automatic money exchange machine has the functions of discriminating 
whether or not a bank note inserted into an inserted bank note 
discrimination mechanism 9 provided in a machine body 8 is acceptable, 
dispensing a prescribed a number of a designated type of bank note from a 
dispensing mechanism if the inserted bank note is judged to be acceptable, 
and returning the same to the inserted bank note discrimination mechanism 
9 if it is judged to be unacceptable. 
Next, a description will be made of the arrangement of a 
thickness-detecting apparatus provided in the inserted bank note 
discrimination mechanism 9. 
A conveying surface, which comes into contact with the underside of the 
bank note 2 to support it, is provided inside the inserted bank note 
discrimination mechanism 9. Conveyor belts 12 which convey the bank note 2 
by clamping it between themselves and the conveying surface 11, are 
provided above the conveying surface 11. In addition, the conveyor belts 
12 are wound around belt rollers 14 rotating about a shaft 13, and run in 
the direction of the arrows shown in FIG. 1. 
Support shafts 15 are provided above the belt roller 14, and each supports 
a portion of a detection arm 16 adjacent to the upper end thereof in such 
a manner that the detection arm 16 is vertically rotatable. A detection 
roller 17 is rotatably provided on the lower end portions of the detection 
arms 16. This detection roller 17 is constituted by large-diameter 
portions (detection portions) 18, which serve as detectors and which 
rotate the detection arm 16 in accordance with the thickness of the bank 
note 2 as they come into contact with the bank note 2, and small-diameter 
portions (notched portions) 19 provided between the large-diameter 
portions 18. The large-diameter portions 18 are provided at a plurality of 
places on the detection roller 17 at intervals along the axial direction 
of the detection roller 17. 
A conventional thickness-detecting apparatus detects the difference between 
an approximately 0.09 mm-thick bank note and a piece of approximately 0.03 
mm-thick adhesive tape, i.e., a 67% error, by a calculation as follows: 
EQU (0.09-0.03)/0.09.apprxeq.0.67 
In order for the thickness-detecting apparatus of the above-described 
embodiment to detect that a joint portion where the bank note and the 
adhesive tape overlap is thicker by the thickness of the adhesive tape, it 
would be necessary for it to detect a 33% error, calculated as follows: 
EQU 0.03/0.09.apprxeq.0.33 
Accordingly, in order to positively detect a displacement corresponding to 
the additional thickness of the adhesive tape, it is necessary to provide 
a higher-grade surface finish than the surface roughness of at least about 
0.03 mm. 
Therefore, in this invention a pin 39 is secured to the upper end portion 
of each detection arm 16. The detection arm 16 is urged clockwise, as 
viewed in the figure, by means of a tensile coil spring 20 connected to 
the pin 39 so as to enable the detection roller 17 to be brought into 
close contact with the bank note 2 on the conveying surface 11. 
In addition, a coupling member 21 is provided between the fixing portions 
and the tips of the detection arms 16, to link the detection arms 16 
together. 
A transmission member 22 is provided for the coupling member 21, and has 
the function of transmitting the rotational motion of the detection arms 
16 to a potentiometer 23. The potentiometer 23 functions as a detection 
mechanism which detects the movement of the transmission member 22, i.e., 
the movement of the detection roller 17, and converts it into an electric 
signal. 
Reference numeral 24 in the figures denotes rollers for drawing the bank 
note 2 into the body of the machine upon completion of the inspection of 
its thickness. 
The detection apparatus having the above arrangement detects a fabricated 
bank note by the following operations. 
When the fabricated bank note 2 is inserted into the inserted bank note 
discrimination mechanism 10, it is conveyed rightward, as viewed in FIG. 
1, by the conveyor belt 12, and passes below the detection roller 17. At 
this point, at least one of the plurality of large-diameter portions 18 
provided on the detection roller 17 is pushed upward, as shown in FIG. 5, 
by one of the joints between the adhesive tape 6 and the bank note strips 
7, i.e., any of the overlapped portions of the adhesive tape 6 and the 
bank note strip 7 which are thickner than a real bank note. As the 
detection roller 17 is raised, the detection arms 16 rotate 
counterclockwise, as viewed in FIG. 1, to actuate the potentiometer 23, 
which converts the displacement of the detection roller 17 into an 
electric signal. 
Furthermore, as shown in FIG. 6, if the fabricated bank note is inserted in 
the direction opposite to that shown in FIG. 5, since the joint portions 
of the adhesive tape 6 and the bank note strips 7 are thicker than a real 
bank note, the detection arms 16 are raised as a large-diameter portion 18 
passes over one of the joint portions to effect detection. 
If an abnormality is detected, the bank note is returned by rotating the 
conveyor belts 12 and the rollers 24 in the reverse direction; but if no 
abnormality is detected, the bank note is taken into the body of the 
machine by the rollers 24. 
The number of large-diameter portions formed on the detection roller and 
the intervals therebetween should not be restricted to those shown in the 
above embodiment; it goes without saying that they may be modified, as 
required, in accordance with the various different types of fabricated 
bank notes that can be foreseen. 
In the above embodiment, a rotary roller is used as a detector, but a lever 
or the like that slides along the surface of the bank note may be used as 
a detector. 
Moreover, the mechanism for detecting the displacement of the detector 
should not be restricted to that of the above embodiment; it may, of 
course, be modified as required. 
As is apparent from the foregoing description, the present invention has 
the following advantages: 
(i) If any one of the plurality of integrally movable detectors comes into 
contact with a joint portion, i.e., a thicker portion, of a strip of bank 
note and a piece of adhesive tape, the detection arms are displaced, 
enabling the actuation of the potentiometer. In consequence, it is 
possible to positively detect a fabricated bank note made by connecting a 
number of narrow strips of a bank note by means of adhesive tape. 
(ii) Since the detector sliding along the bank note is divided into a 
plurality of pieces which are distributed over the entire range of 
detection, it is possible to reduce the area of the detector which 
requires sophisticated finishing, thereby reducing the production costs.