WO2001091063A1

WO2001091063A1 - A coin knurling sensor

Info

Publication number: WO2001091063A1
Application number: PCT/SE2001/001089
Authority: WO
Inventors: Geoff Howells
Original assignee: Scan Coin Industries Ab
Priority date: 2000-05-19
Filing date: 2001-05-17
Publication date: 2001-11-29
Also published as: AU2001258995A1; SE0001861A0; SE0001861D0

Abstract

A coin discriminator analyses an edge pattern of a coin (10) moving past a sensor (20). The sensor comprises an optical source (30) for emitting light (30') onto an edge (40) of the coin and an optical receiver (50) for receiving light reflected from the edge (50'). Furthermore, the coin discriminator comprises a processing device (60), coupled to the sensor and adapted to analyse a signal representing the light received by the optical receiver and in respone determine a type of the coin. The optical source (30) comprises a laser diode.

Description

A COIN KNURLING SENSOR

Technical Field The present invention relates to a coin discriminator for analysing an edge pattern of a coin. The coin moves past a sensor, which comprises an optical source for emitting light onto an edge of the coin and an optical receiver for receiving light reflected from the edge. The coin discriminator further comprises a processing device, coupled to the sensor and adapted to analyse a signal representing the light received by the optical receiver and in response determine a type of the coin. It also relates to a method for analysing the edge pattern of the coin moving past the sensor.

Description of the Prior Art

Coin discriminators are used for measuring different physical characteristics of a coin in order to determine its type, e.g. its denomination, currency or authenticity. Various dimensional, electric and magnetic characteristics are measured for this purpose, such as the diameter and thickness of the coin, its electric conductivity, its magnetic permeability, and its edge pattern, e g its edge knurling. Coin discriminators are commonly used in coin handling machines, such as coin counting machines, coin sorting machines, vending machines, gaming machines, etc. Examples of previously known coin handling machines are for instance disclosed in O97/07485 and WO87/07742. Several methods are known for determining the knurling on an edge of a coin and its denomination. US-A-5 383 546 discloses a first solution with an arrangement for detecting a foreign body in a coin channel or recognizing the edge knurling on a coin passing the coin channel. Light is emitted from an LED diode, which is placed above the channel, and down through the coin channel. Every object that passes the channel either reflects or absorbs light, wherein a detector, also placed above the channel, receives a different amount of light depending on what kind of object that passes through the channel and also depending on whether or not an object passes in the channel. The detected light is measured as a voltage value indicating the amount of received light corresponding to different knurls or present foreign bodies.

Another solution is disclosed in EP-B-311 554, wherein an LED diode, which emits IR light, and a detector are placed in the bottom of a coin channel in which a coin rolls . An opening with glass coverage protects the diode and the detector. The reflection from knurled coins changes, so that the output signal from the detector has an alternating current component, which is converted to digital signals corresponding to the frequency of knurls present on the edge of the coin. Smooth coin edges create no alternating current component, and the measurement of such coins is ended after a certain time. The problem with the first solution is that the LED diode does not give the same accuracy when coins with different diameters are being analysed due to a fixed focusing with its lenses, which makes the reflected light more diffuse and therefore more difficult to analyse. The second solution has problems with dirt aggregating on the glass coverage of the sensors in the bottom of the channel and wear of said glass coverage.

Summary of the Invention The main objects of the present invention are to simplify the construction and the procedure for analysing edge patterns on coins .

These objects are achieved for a coin discriminator adapted to analyse an edge pattern of a coin moving past a sensor. The sensor comprises an optical source for emitting light onto an edge of the coin and an optical receiver for receiving light reflected from the edge. Furthermore, the coin discriminator comprises a processing device, which is coupled to the sensor and adapted to analyse a signal representing the light received by the optical receiver and in response determine a type of the coin. The optical source comprises a laser diode.

The distance between the edge of the coin to be analysed and the sensor is kept constant by a datum edge . The datum edge is placed between the edge of the coin and the sensor and is in contact with the edge of the coin when the coin moves past the sensor during the analysis.

By providing a coin handling machine with a coin discriminator according to the invention, the following advantages are obtained. The focusing is enhanced due to a constant distance between the sensor and the edge of a coin. Consequently, a very simple arrangement may be used for focusing the light emitted onto an edge of a coin, or even no focusing arrangement at all. Moreover, there is no aggregation of dirt over a window placed below a moving coin. Also, wear of the glass is reduced, and the analysis of edge patterns is more exact due to a smaller light spot size provided by the laser diode, thereby providing a wider range of light levels compared to an LED diode.

Brief Description of the Drawings

The present invention will now be described in more detail, reference being made to the accompanying drawings, in which: FIG 1 is a top view showing a sensor according to a preferred embodiment of the invention,

FIG 2 is a side view in section showing the sensor in FIG 1, FIG 3 is a diagram showing output signals from the sensor in FIGS 1 and 2 when analysing a typical knurled coin,

FIG 4 is a diagram showing output signals from the sensor in FIGS 1 and 2 when analysing a typical unknurled coin,

FIG 5 is a side view showing another embodiment of the sensor according to the invention,

FIG 6 is a diagram showing output signals from the sensor in FIG 5 when analysing a typical knurled coin,

FIG 7 is a diagram showing output signals from the sensor in FIG 5 when analysing a typical unknurled coin,

FIG 8 is a circuit showing a preferred embodiment of electronic components in the sensor, and FIG 9 is a flow chart illustrating a method according to the invention for analysing an edge pattern on a coin.

Detailed Description of the Invention

FIG 1 shows a preferred embodiment of a coin discriminator according to the invention. FIG 2 is a side view of the coin discriminator in FIG 1. The coin discriminator analyses an edge pattern of a coin 10 moving past a sensor 20 along a coin path. The edge pattern could be intermediate, continuous, fine, or coarse knurling, or any other kind of pattern, e g symbols, letters or figures. The coin 10 may be transported along the coin path by active means, such as an endless belt or a rotary carrier member using friction for engaging the coin 10. The coin may also be transported along the coin path by gravity, wherein the coin path is defined by an inclined support surface on which the coin may roll, as shown in FIG 5, which illustrates another embodiment of the coin discriminator according to the invention.

The sensor 20 in FIGS 1 and 2 comprises an optical source 30, which emits light 30' along an optical axis illustrated as an arrow extending from the optical source to an edge 40 of a coin 10. The sensor also comprises an optical receiver 50, which receives light 50' reflected from the edge along another optical axis, as illustrated by another arrow extending from the edge 40 of the coin to the optical receiver. Furthermore, the sensor 20 has a processing device 60, which comprises common standard electronic components, such as a central processing unit (CPU) , a digital signal processor (DSP) or a programmable logic array (PLA) together with a filter 62 and an analog- digital converter 64. The processing device 60, the filter 62 and the analog-digital converter 64 are shown schematically in FIGS 1 and 5. Moreover, the processing device 60 comprises a memory, and a set of program instructions is stored in the memory and is executable by the processing device.

The optical source 30 is preferably a laser diode, and the optical receiver 50 is preferably a photo- transistor. The advantage of using a laser diode is that it gives a small spot size, providing a wide range of reflected light levels. The processing device 60 is operatively connected to the sensor 20 and is adapted to analyse a signal representing the light detected by the optical receiver 50 and in response determine a type of the coin 10. Different signal outputs from different coins are illustrated by diagrams in FIGS 3 and 4.

The optical receiver 50 is protected against dirt and damage by a wall 90 placed over the optical receiver in parallel with the moving coin 10. The distance between the edge 40 of the coin 10 and the sensor 20 is kept constant in the embodiment of the coin dicriminator shown in FIG 1. This is done by providing a datum edge 70 between the edge of the coin and the sensor, wherein the datum edge is in level with the coin by at least one side. The datum edge is in contact with the

ii 0 H-¹ rt ft CQ rt H 4 P- d Φ tr Φ rt .V Hi μ- t . .

£T s d rt P- TJ Pi 03 fu Pi £ Φ to φ φ Hi H- 3^J μ- 3" Φ Φ φ 3 Q- fu P- 3 Φ 3 O o μ- CQ 3^J f H μ- 0 Hi μ- φ o Pi

TJ HI Φ ft⁾ LQ φ TJ TS rt 3 LQ 03 LQ Φ d T. P- - 3 d Φ rt fU Hj d Hi Hj fu LQ • LQ ri •A φ rt 3 ϋ Hi Φ fu Φ Φ Hi Hi φ 0 P fu d Ω rt Hi 0 Φ Hi Φ φ H O rt fu tY Φ Φ Ω H ^« fu CQ Φ . rt Hi 0 rt 3 Φ Ω S Ω Hi

CQ Ω Φ rt 3 03 03 rt W 0 μ- Φ 03 φ 3^J $ h-> Hi i ft⁾ φ rf 0 ft⁾ tr . φ ii CQ α 3" 03 d Φ Φ Φ Φ f Ω Hi LQ P. Φ m 3 Φ Φ ^ fu φ 3 H¹ μ- Hi Φ o

3 Φ rt d Φ HJ 3 3 P- Ω- 3 0 3 3 3^J i fu oo 3 P. tr Pi ω H 0 Ω

(i- -.. TJ Φ φ H_. rt rt Ω. 3 f ft⁾ Ω rt Φ Φ Hh Ω o μ- CQ LQ φ O O 3 3 φ p. 0 fu li Ω- Φ φ φ Φ Φ Φ rt 3 Hi μ- 3 0 tr • 3 Tf Φ rt Pi d Hi fu Hi rr 3^* Φ rt TS Q- Pi μ- fi rt μ- 03 Φ 3 P. rt Ω fu ≤. ft⁾ ft⁾ TJ 0 3 f rt

H- 0 n ≥! 0 fu H LQ LQ 3^J 3 d Φ LQ μ- d Ω tti 3 Hi 1 Φ 3 3 0 Hi Φ 3 d rt

<! -S Φ 0 K φ Ω 0 0 t Φ Φ 0 3 Hi f f *< C^Q 0 ^ 0 Φ O Φ fu P. μ- Hi μ- 3 - φ φ 3 li CQ Φ 03 0 3 0 rt . d Φ P LQ μ- μ- 3 _^ 3 LQ 3 3 0 Ω Φ

<! rt S 0 Φ μ- ... CQ 3 *d LΠ φ Hi 0 3 3 d Ω rt Φ rt rt 0 d φ

CQ φ H- Φ 3 3 3 3 rt rt H. 1-3 0 ^•» d Hi o rt Hi LQ 03 0 Z rt 3" μ- <! CQ 3 P. Ω ft⁾ 3 LQ Φ 0 rt tr t-f Φ tr li Hi Φ φ 3 M μ- 3 03 F iy cr Φ 3 φ fu LQ O

3 LQ μ- H μ- CQ Φ Φ Hi Φ S Hi 03 α Ω rt o O 3 rt ft⁾ Φ φ ^ LQ 3 Ω rt Φ μ-

TJ fu CO Φ 3 3" Φ μ- φ Φ Hi π- μ- 3" Hh LQ fu TJ Hi 0 φ 0 Φ 3

H rt rt 3 Ω LQ 0 •< Φ P- LQ 3 Pi 3 Φ 3 Φ 0 Ω TJ Φ 03 fu TJ rt 3 μ- Hi μ-

Φ tT tr ii 0 3 Ω μ- μ- φ rt Ω P- rt 3 ft⁾ rt tr tr φ rt 0 rt 3 μ- 03 H μ- φ t ft⁾ Ω rt 3 fu fu rt fu $u 3 μ- 0 ^ Pi 3^J μ- *< 3 rt μ- 03 $u o

0 m CQ o rt Ω 3^J . < Φ LQ 3 W 0 3 μ- H H μ- Φ f P. t Hi 03 Hi Ω rt 0 H 3

Hi φ Ω d Φ μ- μ- μ- Q- HJ 3 H. LQ 3 μ- Q fu ft⁾ μ- (0 f 0 ft⁾ u y Hi TJ ft⁾

Ω « tr H 3 CQ 03 ft⁾ to d ^ LQ 3 03 Ω rt rt tr Hi 3 H-¹ Φ ft⁾ 0 Pi tr rt 0 03 HJ Φ φ d •* Hi 3 o ii Φ P. tr ω φ φ 0 d 3^J LQ Φ 03 rt CQ Hi Φ Φ

3 H- Ω CQ 3 3 >*_ H 03 LQ φ fu rt rt 3 3 3 _o TJ Hi Hi 3^J CQ 3

2 Ω Ω tV H 1-3 μ- O F. φ μ- rt 3 03 Φ 03 03 rt P⁾ o o ft⁾ φ μ- Φ μ- tr 0

H- ft⁾ 0 Ω Φ 3 Ω 3^J 3 3 μ- Hi P- f Φ P. Hi tr H 0 rt Φ 3^{^} 03 TJ Hi Ω LQ 3 fu Hh rt Q e

Ω H- rt μ- fu C d Φ H-¹ 3 Ω Φ 0 HJ f P. Φ 03 rt f Φ Φ tr Ω LQ Hi - ft⁾ CQ Ω 3 d H. ω Hi rt Ω ^-. rt rt Hi $ Hi 3 LQ μ- 3 3 μ- rt 0 Pi fu Φ

H" !-r CQ ft⁾ O φ 3" d 0 fu t Φ tr H CQ 0 μ- rt Φ rt $. Ω Pi rt <! μ- rt

Ω φ rt φ 3 Φ 0- d Φ 03 μ- . o P- Φ Φ H 03 Hi μ- fu φ μ- 3 3^J 3 S Ω

--. 0 C^Q tr Ω- Ω- Q- μ- rt fu rt 3 . Ω rt P. ! f 3 h-¹ rt 03 Hi 3 Φ φ Φ 0

0 13 Φ Hi TJ rt Φ Hi Hi f*. H-¹ P. r tr φ 03 μ- O 3 P. ΪT fu H rt fu μ- li CΩ H- ti tr 3^J Ω Hi d μ- Ω- fu 3^J 0 Hi μ- μ- Φ Φ fu μ- CQ _^ 03 0 fu Φ TJ Ul ^!T1 O P. ft⁾ Hi 3

-3 H- 3 Φ *<. μ- 0 φ rt 0 LQ rt f X LQ f P. Ω M rt Tf s X TJ O H fu h-¹

Φ P. LQ μ- H 3 Φ Φ CQ μ- Ω tr LQ 0 3^J O ft⁾ $, fu Φ Ω tr Ω μ- rt Hi 3

LQ Φ rt fu s tr 13 03 CQ 3 0 rt Hi Hi d 3 tr Hi 03 0 μ- ft⁾ 03 d Φ 0

H- i 3^* ii Φ Φ μ- rt _-=> rt 3 fu μ- f H rt Ω μ- Ω μ- Φ ι-3 μ- Hi Hi H 3 Hi 03 < fu φ φ φ fu H 03 Hi LQ O O tr O rt 3 H. 3 0 TJ 0 Hi φ Ω 3 3^J ω 3 Φ Φ . Hi 0 μ- Φ

3 i ST i 3 Φ Φ Φ 3 3 μ- μ- t rt Φ O φ φ Hi 03 03 l-h CQ Hi 0 0 f rt 0 W Hi μ- rt 3 φ Hi — H LQ TJ H TJ Pi rt t rr H 0 0 H 3 H H- Hi Hi 3 ^■<! Hi H-¹ 3 u • P. H t 03 Ω O Hi tr Hi LQ -2 ft⁾ TJ o 0 Φ 3 3 φ 3 CQ 3 Hi d 13^* Φ 3 CQ 0 φ ft⁾ 0 f ft⁾ 0 φ Φ Φ μ- 3 fu

Λ φ Λ rt Φ f φ HJ o Φ Ω I μ- f 3 φ . H- 3 fU 03 rt CQ rt ct CQ

N tr d rt d μ- tr Hi μQ H • rt H Φ LQ 3 Ό s 3 i 3 01 Φ 0 Φ tr rt ii Φ Φ <! - φ ø Φ Φ rt Ω d μ- cπ σi Φ Ω P- 3 Pi rt CQ tr Pi Ω TJ 3 O 03 3

3 φ φ 3 TJ 0 Φ 3 o P- LQ ft⁾ 3^J μ- H Ul ≤ rt rt rt . rt f rt

Ω fu Ω H. Ω Ά O ii μ- 3 LQ 3 Φ 03 φ rt H o O f μ- φ μ- φ fu rt W

0 ^ rt φ ^■ : H d φ 3 Ω 3 α Hti 03 Φ 3" Φ - if 3 P- Ω P- H3 3 Φ Φ

H- μ- P. Ω rt 03 - ^ f Hi Hi CQ 0 Ω CQ Φ μ- 0 Pi ft⁾ 3^{^} Hi

3 TJ Ω LQ TS φ 3 . 0 ty Hi d Φ LQ CQ Ω < 0 H) r Φ μ- μ- 03 ra ti fu φ φ *- d 3 Hi Q- μ- Ω 3 0 HJ 3 Φ H Hi φ ≤ Hi •<! 3 fu Φ

• 0 <! rr rt rt o $, 0⁾ Φ 03 P. u 0 0 LQ (-^■ 3 l-h 0 φ μ- μ- 0 f Ω μ- f w P- 0 LQ 03 03 rt oo 3 ft⁾ - CQ

H- Hi 3 3 Hi 3 tr 3 3 Hi Φ 03 CQ tr O 3 rt 0

CQ LQ Φ tr H.

Φ Φ

ω > to t ι_κ o o o

Ω Pi rt Ω TS Hi Hi rt H 3 rt tr σi μ- fu TJ o fu Hi 0 ω ω φ 03 03 μ- rt rt 03 3 Pi

0 μ- tr 0 H μ- 3^J 3" Φ 0 S ^■ : o 3 03 Hi TS 3 H T o μ- o 3 φ d tr 0 d o μ- μ- Hi φ 3 0 LQ φ Φ Ω d _^ Ω 0 rt 0 0 rt tr 3 TJ μ- Hi <! 03

3 Hi 03 rt tr Φ 3 Φ rt h-¹ μ- Ω μ- rt 3 μ- fu 0 03 TS d 03 rt Hi Φ Ω

03 φ Ω rt Φ rt 0 P- μ- rt 3" Hh d 3 Φ Ω 3^J Ω tr d ^ Pi O 0 03 3^J fu 03 Hi

K 0 Hj Ω TJ μ- <! Φ 0 Φ 0 pⁱ CQ fu Φ rt fu 0 03 tr μ- Hi Hi rt φ Φ Ω μ- ft⁾ α Φ μ- d rt fu rt Hj φ Pi m Hi Hi μ- rt 03 Hi 3^J H-¹ < rt μ- 3 rt Hi 3 Φ fu 3 ^

CQ μ- 3 3 Ω Φ 3 μ- φ Hj 3^J 0 3 tr μ- Φ φ Hi Ω φ Ω fu tr Hi μ- H

Hi rt rt P. LQ Ω Ω μ- Φ rt TJ fu LQ Φ 3 Hj fu Hi fu 3^J 3 0 CQ rt 0 μ- H 0 3 Ω μ- Hi H μ- ft⁾ rt TJ 3 3^* rt 3 LQ Φ Hi Φ φ rt rt rt d Φ P. LQ O 3 fu

3 Φ P. o 0 μ- φ Ή μ- 0 Φ μ- ft⁾ rt Hh Ω Hi Pi Ω 3^J Φ φ TS Hi Pi μ- 3^J O LQ rt in

Hi μ- 3 3 03 0 J fu S Ω pr μ- P. φ 0 LQ φ Φ i 3 μ- Hi Hi 3 rt O

^1 φ ft⁾ fu 03 3 Ω rt Ω fu ^ Φ H_. φ μ- ^ Φ μ- μ- H-¹ μ- fu μ- φ . μ- fu H μ-

H 3 3 3 3 rt rt 0 Φ Hi μ- 0 H 03 03 <! < < Ω tr rt H-¹ 03 Ω 3 3 3

Ω rr φ P Φ £r 0 d 0 P. 0 Ω μ- μ- 0 rt μ- Φ φ fu φ 0 ^ 03 d φ Φ rt Hi Ω fu r->

CQ rt ft⁾ Φ Hj Hh -3 ft⁾ 3 Hi 3 TJ Ω Hi X H Hi μ- 03 03 4a tr rt 0 Ω d

03 Φ rt 3 rt Ω f H φ LQ rt Φ Φ rt 0 3 fu H-" r H H 0 Φ 3" μ- Ω CQ ω μ- Hj 3^J 03 CQ 3" φ Ω Hi fu H Ω μ- 3 σi Φ 3 U1 3 μ- Hj rt o Ω Hi Φ 3 0 rt

LQ 03 Φ ft⁾ Φ 0 rt tr 03 o φ f Ω tr μ- o 3 LQ o rt LQ fu ^{^} o 03 HJ Hi f 3 rt 3 fu μ- Φ o 0 • μ- fu 0 03 ^• — * Pi - 0 fu tr rt φ in rt fu Pi TJ Pi fu

3 fu fu 03 3^J Φ μ- 3 3 H <! d <! 03 P. _^. μ- fu Hi rt φ TS " 3 μ- fu μ- rt

P. H" H; Φ f 3 fi φ Hi φ μ- μ- 0 3 3 2 u Hi Pi 03 0 fu Φ φ Hi rt 3 Φ φ 3 rt 3 Ω 3 rt Ω Hi LQ 03 3 TS fu LQ 0 tr 3 0 ω fu μ- 3 φ 3¹ CQ CQ

0 03 ft⁾ H-¹ rt 0 3^J rt Φ 3 0 Φ φ 3 rt μ- S o μ- 3 3 P. Ω CQ Ω d rt O rt 3 μ- 3^J <! Φ fu fu d 3 Hi Pi Hi & Ω Φ - 3 Φ rt 0 φ rt tr rt fu ft⁾ rt 0 Hi 3^J 3 3 Φ Φ Φ ω 3 H-" Hi rt ft⁾ Hj Φ 3^J Pi Φ μ- μ- μ- 3 μ- * ; 0 3

Hi TJ Φ φ φ 3 0 o Pi Ω rt rt 0 Hi LQ X fu ] Ω 3 03 3 03 0 0

Φ d t to H P. 0 Φ TJ Ω Hi Φ μ- μ- 3" 3 Hi Φ rt H-" μt 0 LQ 0 3 Hi rt rt rt φ o P- TS 3 rt O fu μ- Φ 3 <! Φ 0 φ Φ O Ω 3 TS P- H 0 3^J 3" μ- CQ μ- ft⁾ 03 rt rt μ- μ- 3 3 TJ ω φ rt TJ Ω πP- 3 3 CO TJ P- H-¹ μ- 0 H-" Φ Φ

H-¹ fu < 03 CQ d μ- Ω 3 Pi Hi o ^ h-¹ TJ 3^J rt φ o Pi LQ 0 0 fu 03 to Hi Hi

Hi 3 ft⁾ rt TS Ω μ- ft⁾ Hi Φ H *< Hi Φ μ- μ- μ- M 3 ≤ Ω Ω O μ- μ- d Hi fu Hi ft⁾ μ- TJ ft⁾ 3 H-" TJ rt φ 03 ft⁾ Ω 0 Ω o 3 fu 1 Φ 3 Φ H fu 3 3 Φ

03 0 H-¹ μ- 3 3 0 P. f B 03 Φ 3 to Ω Ω Φ ft⁾ φ Hi LQ 3 [O 3 fi μ- fu 3 LQ <! 3 rt 3 > : φ Ω Hi μ- 03 rt Φ TS 3 P 0 Φ P h-¹ CQ rt rt 3 03 Φ tr

Hi 03 03 Φ 1 rt Hi Ω 0 3^J 0 rt H 3 CQ LQ rr Hi 0 03 O fu H- fu 0 3 0 ft⁾ rt φ H Φ fu d 0 3 μ- rt 1 3 03 Φ fu H-¹ 3^{^} H TJ μ- S tr 3 μ- H 3 rt Pi rt F Pi μ- tr Ω CQ Ω rt Hi 3 TS 03 3 3" to Φ μ- X μ- φ 0 rt fu fu 0 fu 3 Hi μ- μ-

Φ Φ Hh Φ CO d Φ Φ Ω μ- rt φ LQ Φ •• Ω 3 μ- LQ 3 μ- φ 03 Hi <j rt 0 ft⁾ 0 3

P. rt Hi μ- P. φ rt μ- rt LQ o 03 3¹ Ω Ω i Φ 0 *τ] £ 3 3 φ

03 Ω => H Hi < ¹ Ω P. rt 0 rt Φ rt 0 rt fu rt μ- CQ Hi H 3 tr ft⁾ 0 Φ fu Φ tr ft⁾ φ 3^J S 0 P P- 0 . — . μ- 3^J H-¹ 3- 3 rt Ω H μ- rt

^ 3 H- Φ ft⁾ Ω 4 ^ μ- rt rt Φ rt - φ Hi μ- LΠ 3 Φ φ rt 3" CQ to 3 W

Φ 3 3 3 Φ 3 t Φ μ- rt < H o fu rt 3^J Φ Hi O Ω Φ 0

Pi CQ Pi TS rt Φ Hj Hi H-¹ Ω t μ- μ- rt H-¹ - μ> 0 X 0 tr Φ tr H H. H μ- rt rt H 0 3¹ Hi φ 3 μ- f Φ 3 Ω tr d o TS μ- TS Φ μ- Φ 1 TJ μ- Φ fu s. -S 3^J t o μ- Φ φ 0 Ω μ- LQ H φ φ Q Hi - — rt 03 rt Ω 3 M 0 3 rt

LQ 0 μ- Φ . o 3 TJ φ 3 Q rt rt Φ _^. μ- μ- Hi o Ω 03 μ- Φ 3^{^}

Hi rt rt fu fu rt μ- μ- rt Hi Φ tr en Ω Hi Hi Ω Ω μ- μ- H-¹ φ μ- 3 P. rt Φ fu rt tr φ ι-3 fu H rt μ- <! 3 Φ 3 Φ o o fu rt fu fu H 3 μ- 3 CQ rt ^{^}

3 • ! Pi tr 3 i Hj μ- Ω Φ LQ Hi Ω 03 μ- rt Φ 3 H-" 03 3 CQ μ- 03 Φ Ω

CQ TS LQ μ- Pi 0 0 0 ft⁾ Hj φ φ 0 CQ 3 Φ Ω Φ rt H Φ 0 d 3 d 0

Φ Φ 03 3 $ 3 H-¹ rt Ω μ- Hi fu m P rt 03 03 o P- Hi 03 LQ TS Ω μ- μ- 03 f 3 σi 3^J Φ < 3 3- rt Φ 0 0 φ TS 0 3

3 Hi H rt o Φ μ- φ t φ Φ 0 tr P d d to Pi Pi 0 μ-

0 o φ fu to 0 < Hi o Hi Hi Hi O 0 Hi 3

Hi rt o fu Φ rt Ω Ω 3^J μ- rt 0 Hi P ft⁾ 3" φ φ Φ μ- 3 3 H

Hi Φ Φ 03 o

FIGS 6 and 7. FIG 6 shows the output signals representing the reflected light from the edge of the Greek 50 Dr coin, and FIG 7 shows the output signals representing the reflected light from the edge of the Norwegian 20 Kr coin. The vertical lines are caused by the light being reflected by the knurling of the coin as the coin rolls. The Greek coins are very variable in the quality of the knurling on the edge. Some coins are deeply knurled, while others only have a series of black scratches on the edge. However, the diagram in FIG 6 is considered to represent the output signals of a typical Greek 50 Dr coin. The difference between the output signals from the two coins and the overall frequency profile for each coin in FIG 6 and 7 are easily analysed for determining the type for each coin. FIG 8 is a circuit diagram illustrating a preferred embodiment of the analog electronic components used in the coin discriminator according to the invention. The light from the optical source 30 is reflected from the knurling and received by the optical receiver 50 shown to the left in FIG 8. The two op-amps and the analog electronic components in the middle of the circuit form a band pass filter 140. This band pass filter has a centre frequency of about 8kHz and a Q value of about 4.

Q is defined as f/df, wherein f is the centre frequency and df is the frequency difference between the high and low points. The high point means the centre frequency that is high enough so that only 50% of the amplitude passes through the band pass filter 140. The low point means the same 50% amplitude, but below the centre frequency.

The pitch of the knurling and the speed of the coin 10 past the sensor 20 determine the centre frequency. A coin travelling at 4m/s and having 0.5 mm pitched knurling will produce reflections at a rate of 8000 per second. In practice the optical receiver will see about 30 or 40 reflections depending on the coin diameter. The low value of 4 for the filter Q value allows this small number of reflections to be seen and can handle pitches, which are not exactly 0.5 mm. A last op-amp 150 to the right in the circuit in FIG 8 is used as a comparator, which converts and inverts the filtered analog output signals from the band pass filter 140 into digital signals. The band pass filter 140 creates a low output when more light is reflected and received by the optical receiver 50, and when the comparator inverts these signals a low input creates a high logic level and vice versa. Because of the band pass filter, the digital output is most sensitive to light varying at 8kHz. The digital signals from the comparator 150 are timed for measuring how long each high and low period is.

The timing is done by a very fast single chip microprocessor (not shown) . One pin of the single chip microprocessor is connected to a comparator output 160, which is shown to the right in the circuit in FIG 8. The other pins are connected to one side of a dual port RAM (not shown) except for a final pin, which is used as trigger input connected to a PC (not shown) . This trigger input is used to start the timing measurements as the coin 10 approaches the sensor 20. The software on the single chip microprocessor operates as follows: a level change on the trigger input supplied by the PC causes the single chip microprocessor to time the high and low periods on the input from the comparator 150. As each high or low period is measured, its length in time is stored in the dual port RAM. A typical coin 10 that gives 40 reflections from the knurling will produce about 80 numbers in the dual port RAM.

The other side of the dual port RAM is connected to the PC, which provided the trigger input to the single chip microprocessor based on the readings from other coin to to o 5 o

Ω 03 Hh H SD Hi CQ Hj fu Hi rt TJ Hi 0 Hi VD 03 TS Ω H Pi tr 03 IT 03 rt Hi 3 03

0 fu μ- μf- 3 0 μ- μ- Φ tr tr tr Φ TS Φ H μ- fu 0 O μ- ^ 0 3 0 μ- μ- f φ

3 3 H O fu Hi LQ LQ Hh Hh φ φ 0 TS rt Hi o 3 03 3 03 Hi 0 Hi 3 H Ω 3

< T⁾ rt H tr 3 μ- rt Hj μ- H-" • d rt φ μ- Ω rt rt S rt φ tr CQ

Φ H-¹ φ μ- 0 Hj rt fu Φ Hj TS TS 0 Φ Ω Φ μ 03 03 Hj tr % 3 S CQ φ μ- 0

W Φ Hj 3 LQ Φ H-¹ Ω 03 t tr Ω CQ fu Ω rt rt μ- Φ ft⁾ fu Pi 3 Hi rt Hi Φ 3 H3 ft) rt rt 0 0 d φ H-¹ rt H. fu tr μ- 3 3 H3 Hj Ω Hj fu Φ 03

Φ tr 0 i rt Φ 0 3^J 3 Ω CQ rt rt Hj 3 Φ tr 3 Φ 3 0 μ- Hh tr Φ 0 Φ 3 tr .

P Φ Hi 3^J H < Φ . 0 m 0 0 Hi rt Hi Pi Φ Φ <! 3 0 φ μ- . ^ _^-.

3 fu Φ φ μ- 03 3 H-¹ tr¹ Ω Ω Φ μ- φ 0 03 Ω Φ fu H-¹ 03 3 3 3 fu rt 3 Ω 3 Φ μ- TS Φ o d d 3 3 Ω fu d Φ 0 i rt H fu μ- φ rt Hi 0

3 rt 3" fu 3 rt LQ 03 fu CQ -j HJ Hj rt LQ Φ 3 μ- 03 3 3 0 0 3 3 03 fu φ tr rt rt

Pⁱ tr Φ H- μ- H fu Hi 03 μ H Hi μ- P LQ H- 03 rt μ- Hi ^ fu TJ TJ 03 Ω φ Φ φ 03 0 Pi 0 d 3 Pi φ φ Φ Hh rt <J tr •<! 0 fu 3 μ- φ d μ- Hj CQ μ- 03 φ LQ P. 3 3 fu φ Pi 0 3 3 H tr φ i rt Hi Ω Ω 3 ^ ^ φ Hi P. 03 tr

3 Φ μ- S H-¹ rt μ- TJ rt rt O φ Hi φ μ- rt fu μ- LQ 03 P. Φ Φ μ- fu 0

<! 03 o φ Ω fu 0 Φ rt LQ 1 S rt ω t H. μ- Ω 03 03 3 ≤ φ Hi μ- d 3 LQ Ω O tr fu μ- μ- μ- Hi Ω Φ o H-¹ O s; Hi Ω Ω CQ 0 fu LQ Pi 3_^

HJ μ- LQ rt 0 Ω rt rt rt 3 03 CQ 3 φ Hi Ω - d _^ μ- μ- d 0 d 3 rt μ- Φ rt 3 TS Hi 0 Φ O Φ fu TS LQ Hh Φ rt 3 rt H. μ- 3 0 3 Pi tr Hh φ •

Φ rt fu d 3 Pi d P. fu fu TS h-> ft⁾ φ φ μ- fu tr 03 rt CQ Hi rt φ fu

P- φ rt rt TS rt TS 3 μ> 3 Hi rt φ rt P 3 3 3 rt φ CQ rt rt Ω ^< m

Hi 03 3^J 0 3 TJ fu Φ P. ω TS 0 tr Ω Φ μ- ft⁾ fi rt μ- Ω rt tr TJ t tr tr μ- Φ 03 Φ 3 0 d 03 fu o H- TJ Hi rt CQ tr rt rt tr 03 3 d rt φ μ- φ μ- rt μ-

3 Pi μ- μ- φ μ- rt PT μ- • μ- 0 0 Φ *< rt φ rr Φ rt rt Φ tr rt TJ O 03 rt 03 LQ Ω 3 03 fu CQ Hh Hi d Pi fu Φ Pi tr Φ ^1 μ- φ fu Ω Ω

0 fu 3 μ- rt Φ 03 3 0 ! μ- rt LQ 3 rt P. Φ P. TS H <! Φ <! tr 0 3 ft⁾ TJ

3 rt fu Hi 03 μ- Hi P φ μ- tr (-^■ fu tr tr fu Ω φ Pi 3 Φ μ- μ- Ω

P< fu fu H-¹ Ω tr LQ -_- φ rt P. 0 μ- H-¹ Φ tr ; Φ rt KΩ LQ d Hi 0 3 Ω H-¹ μ- H tr CQ d Hi *< 3 0 TJ rt H 3 rt LQ 0 ^ i d O oo 03 Φ 3 fu Hi Hi 0 3

LQ 0 Φ μ- 0 fu 3 μ- Φ 0 fu u tr tr LQ 0 rt LQ 3 O - rt tr LQ H 0 -3 ⁾ μ- LQ 3 μ- rt H rt H = rt Ω d 3 h-> φ rt TJ rt tr φ Φ T. Φ Φ rt O T *< rt 03 3 tr 03 Ω rt CQ Pi 0 rt tr Φ Φ μ- ft⁾ TJ fu Hi tr Hi rt fu 0 Φ μ- μ- Φ 0 t Φ tr rt 0 in d μ- Φ P. 3 03 03 rt tr φ μ- 0 tr Ω

H d <! Ω 3 3 fu Hi Pi Ω 0 T o rt Ω 0 O LQ rt «. rt 0 μ- 03 Ω Φ 0 rt Φ 0 LQ rt Hi 0 0 rt - TJ SD 0 TS Φ 0 03 Φ Hh LQ Φ 3

TJ TJ Hi 3 ^ =3 φ - 3 fu 3 3 rt μ- d H-" TJ rt 0 tr tr Hi tr 3 r 03 Pi rt d d << rt H rt o H tr 03 < tr Ω μ- rt rt μ- Hh o rt 0 ^■<! 3 tr d 3 03 d ii

H-¹ rt μ- Ω tr Hh - μ- rt Φ φ fu 3 Hi μ- Ω O tr $, μ- u H d 0 ft⁾ 0

03 in 3 Φ 0 μ- Ω fu tr H -¹ 03 Φ Ω fu rt . Φ 3 3 O LQ 3 H- Hi Hi H-ⁱ H φ CQ 0 00 TJ H-¹ 03 tr 3 Φ rt H-¹ rt μ- Ω fu H-¹ tr Φ Hi tr Pi μ- H-¹

03 μ- ^*5= d . tr 1 rt μ- Φ μ- Hi tr IQ Φ φ Hi 03 μ- fu 3 Φ TJ fu

LQ 03 CQ fu fu Φ LQ Hi =: φ P- LQ Φ Φ 3 μ- 03 tr Φ 3 3 fu fu H-¹ LQ P. rt 0 μ- 3 . M 3 3 Hi 3 Φ 0 P. tr Ω fu < 03 0 Ω φ 3 03 3 0 tr Hi Ω

3 fu ^ fu Pⁱ TJ φ fu Hi Hi LQ rt rt Φ Hh H φ 0 d 0 3 03 43 Ω Pi -3 tr 0 φ rt 0

H-¹ Ω CQ Pi H M Hh Φ 0 μ- 0 CQ Hi d Hi μ- 0 H 0 0 f Hj μ- rt 03 Ω tr TJ • Φ = μ- < Hi Hi Ω 3 μ- Hi Ω Hh μ- H-' rt 03 TJ t 3

3^* 0 fu fu μ- Ω o ft⁾ 3 Φ 3 μ- in Ω Φ rt 3 0 μ- Φ 3 o v

Φ fu d 0 03 3 3 rt 0 Hi rt Hi 3 o Φ μ- fu K£> rt 3 Pi o ^j tr

Hi 3 Hi CQ Pi 03 Hj <! Φ _^ o . ϋJ 03 μ- Hi . tr μ> 03 φ rt Hj u

3 φ rt 03 rt 0 3 Hi CQ μ- O 03 Φ φ O • CQ 0 • Φ rt 3

Φ φ rt Hi rt rt 3 tr H 03 S rt m CQ fu Hi 3 fu 0 α

X . tr μ- 3^J Φ 0 O φ rt μ- tr fu Φ tr μ- 3 tr Ω μ- ι-3 i H-¹ rt Φ Φ TJ Hi ⁼ fu rt Φ TJ Φ 3 0 fu Φ 0 03 0 rt tr 03 tr μ- fu rt φ Ω LQ Hi < 3 μ- Hi tr φ φ 3

CQ 3 Φ to 0 Φ • Φ ω 03 φ Pi Ω 3 Pi Φ rt LQ rt Pi Hi ω μ- μ- ιo rt Pi 0 0 rf *ϋ tr

Φ o 3 tr 3 o Φ μ- 3 tr Ω φ

TJ fu K . TS 3 Φ φ

940 by the last op-amp 150 serving as the comparator at the right hand of the circuit in FIG 8.

This is followed by a step 950 in which a "list of numbers" is created representing the digital pulses. For each coin there will be a series of numbers produced relating to the duration of time during which a "0" signal is recorded and the duration of time during which a "1" signal is recorded. These numbers are then used to produce a single number, which is the number of peaks recorded for that coin 10. The digital pulses in the form of the "list of numbers" are analysed by the processing device 60, whereby the type of coin is determined and the coin 10 is discriminated/identified in a last step 960. This discrimination is done by comparing the number of peaks with a preset threshold level, i e if the number of peaks is greater than this threshold level, then the coin is knurled, and if the number is less than the threshold level, the coin is unknurled.

Claims

1. A coin discriminator for analysing an edge pattern of a coin (10) moving past a sensor (20) , the sensor comprising an optical source (30) for emitting light (30') onto an edge (40) of said coin and an optical receiver (50) for receiving light reflected from said edge (50'), the coin discriminator further comprising a processing device (60) , coupled to the sensor and adapted to analyse a signal representing the light received by said optical receiver and in response determine a type of the coin, c h a r a c t e r i z e d in that said optical source (30) comprises a laser diode and that the distance between the edge (40) of the coin (10) to be analysed and the sensor (20) is kept constant by a datum edge (70) , which is placed between the edge of the coin and the sensor and is in contact with the edge of the coin when the coin moves past the sensor during the analysis.

2. A coin discriminator for analysing an edge pattern of a coin (10) moving past a sensor (20) , the sensor comprising an optical source (30) for emitting light (30') onto an edge (40) of said coin and an optical receiver (50) for receiving light reflected from said edge (50'), the coin discriminator further comprising a processing device

(60) , coupled to the sensor and adapted to analyse a signal representing the light received by said optical receiver and in response determine a type of the coin, c h a r a c t e r i z e d in that said optical source (30) comprises a laser diode and that the coin (10) rolls in a coin channel (120) with a slope past the sensor (20) , which is placed in the coin channel above the coin, during the analysis of the edge pattern.

3. A coin discriminator according to claim 1, wherein the datum edge (70) is made of a wear resistant material, e g a ceramic material or hard metal.

4. A coin discriminator according to claim 2, wherein the optical receiver (50) is a phototransistor .

5. A coin discriminator according to claim 2, wherein the processing device (60) comprises: at least one of a central processing unit (CPU) , a digital signal processor (DSP) or a programmable logic array (PLA) ; together with a filter (62) , which removes unwanted noise, an analog- digital converter (64) , which converts the analog output signals created by the optical receiver (50) into digital signals, and a memory; and a set of program instructions stored in the memory and executable by the processing device .

6. A coin discriminator according to claim 5, wherein the pattern on the edge of the coin (10) could be, e g intermediate, continuous, fine or coarse knurling, or any other kind of patterns, e g symbols, letters or figures.

7. A method for analysing an edge pattern of a coin (10) moving past a sensor (20) , the sensor comprising an optical source (30) for emitting light onto an edge (40) of said coin and an optical receiver (50) for receiving light reflected from said edge, c h a r a c t e r i z e d by the consecutive steps of moving a coin (10) in front of the sensor (20) as a first step (900) , emitting light onto the edge (40) of the coin by an optical source (30) of the sensor (20) as a second step (910) , receiving reflected light from the edge of the coin by the optical receiver (50) , and in response generating analog signals in a third step (920) , filtering the analog signals for removing unwanted low and high frequencies or noise in a fourth step (930) , counting and converting, in a following step (940) , the filtered analog signals into digital pulses, creating a list of numbers representing the digital pulses in terms of the length of each pulse and the length of the gaps between the pulses in a next step (950) , and analysing the list of numbers in a last step (960) so as to discriminate between coins with approved edge patterns and coins with no edge patterns or non-approved edge patterns .