Coin and method for testing the coin

Abstract

A coin comprises a core made of a first metal, an outer ring surrounding the core concentrically and made of a further metal, and a central ring between the core and outer ring fixedly connected thereto. The central ring consists of an electrically insulating material. Further, the central ring is transparent to electromagnetic waves of a first wavelength range and is less transparent or not transparent to a second wavelength range. Methods for testing the coin are also described.

Claims

1. A method for testing a coin, comprising: moving the coin through an optical arrangement and through light in a visible or an invisible range transmitted by at least one optical transmitter, wherein the coin has a core of a first metal, an outer ring of a second metal, and a central ring of electrically insulating material arranged between the core and the outer ring, and wherein the central ring is transparent to electromagnetic waves of a first wavelength range and less transparent or not transparent to a second wavelength range; receiving by an optical sensor arrangement light passed through the central ring; generating by an evaluator a signal when the coin is moved past the optical sensor arrangement, wherein the optical sensor arrangement is sensitive for both the first wavelength range and the second wavelength range, namely for light passed and light not passed or partially passed through the central ring; and generating by an evaluator a genuine coin signal when the optical sensor arrangement does not respond to light not passed or partially passed to the optical sensor arrangement.

2. The method according to of claim 1, further comprising: analyzing by the evaluator the signal generated when the coin is moved past the optical sensor arrangement; and producing a genuine coin signal if a spectrum of the received light corresponds to the electrically insulating material of the central ring of a genuine coin.

3. The method of claim 1 wherein the optical sensor arrangement is sensitive to a wavelength range of visible light.

4. The method of claim 1 wherein the optical sensor arrangement is sensitive to a wavelength range of invisible light.

5. The method of claim 1 wherein the optical sensor arrangement is sensitive to electromagnetic waves in a wavelength range of visible light and electromagnetic waves in a wavelength range of invisible light.

6. The method of claim 5 wherein the optical sensor arrangement includes two sensors.

7. The method of claim 1 wherein the light is produced by an LED.

8. The method of claim 1 wherein the optical sensor arrangement includes a phototransistor.

9. The method of claim 1 wherein the optical sensor arrangement includes a surface sensor or line sensor.

10. The method of claim 1, further comprising determining mechanical dimensions of the coin by means of the signals of the optical sensor arrangement, the mechanical dimensions including a width of the outer ring, a width of the central ring, a diameter of the core and a diameter of the coin.

11. The method of claim 1, further comprising passing the coin through two optical paths which each include an optical transmitter and an optical sensor, wherein one path operates at wavelengths in a visible spectral range and the other path operates at wavelengths in an invisible spectral range.

12. The method of claim 1, further comprising: activating temporarily an optical transmitter in sequence; and producing firstly light in a visible spectral range and secondly light in an invisible spectral range, wherein the optical sensor arrangement is sensitive to electromagnetic waves in a visible spectral range and electromagnetic waves in an invisible spectral range.

13. The method of claim 12 wherein the optical sensor arrangement includes two optical sensors of different sensitivities.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1A shows a plan view of a coin made of three materials.

(2) FIG. 1B shows a sectional view along line B-B in FIG. 1A.

(3) FIG. 2 shows a schematic view of the coin according to FIGS. 1A and 1B when passing through two light barriers L1 and L2.

(4) FIG. 3 shows the response of the light barriers to different materials of the central ring of the coins.

(5) FIG. 4 shows a schematic view similar to FIG. 2 with two light barriers on top of one another.

(6) FIG. 5 shows a sectional view of an optical arrangement for carrying out a method according to the invention.

(7) FIG. 6 shows a schematic view similar to FIG. 2 with a line detector or surface detector for the optical arrangement.

(8) FIG. 7 shows a sectional view of the optical arrangement according to FIG. 6 for carrying out a method according to the invention.

DETAILED DESCRIPTION

(9) Shown in FIGS. 1A and 1B is a coin 10 consisting of three parts, namely having a core 1 made of a first metal material, an outer ring 2 made of a second metal material and a central ring 3 made of an electrically insulating material, for example a polymer. Moreover, the material of the central ring 3 may be translucent or transparent. The thickness of the core 1 is indicated as dd and the thickness of the outer ring 2 is indicated as dr.

(10) Shown in FIG. 2 is a coin running track 20 along which the coin 10 rolls. Two light barriers L1 and L2 are arranged in the spacing a, said light barriers being at a height h above the coin running track 20. The light barriers consist, for example, of at least one optical transmitter and an optical receiver or sensor on different sides of the path of the coin 10. The light barrier L1 operates with light in the visible wavelength range and the light barrier 2 operates with light in the infrared wavelength range. When the coin 10 passes the light barriers L1 and L2, time recordings are made when the light barriers L1, L2 are interrupted. The interruption takes place for the first time when the edge of the coin 10 passes into the light barrier L1 and represents the time t0 in FIG. 3(a). At this time, both (transparent and non-transparent) wavelength ranges are blocked. However, if the edge of the transition from the metal outer ring 2 to the central ring 3 passes the light barrier L1, the transparent wave range is detected by the optical sensor of the light barrier L1, which is represented by the time t1. At the transition from the central ring 3 to the metal core 1, both wavelength ranges are blocked once again. This occurs at the time t2. When the second half of the coin 10 passes, the times t3, t4 and t5 are similarly determined. The individual ring widths or, respectively, the core diameter and the entire coin diameter may be detected from the determined time periods t0 to t1, t1 to t2, t2 to t3, t3 to t4 and t4 to t5. Such detections are described in DE 27 24 868, EP 0 839 364 and EP 0 694 888, for example. The determined individual ring widths may be used as security features.

(11) The light barrier L2 is positioned at the same distance from the track 20 as the light barrier L1 and the spacing a between L1 to L2 is known. From these preset measurements the mechanical spacings of the coins may be calculated. The light barrier L2 is designed for a specific wavelength range, for example infrared light. For this specific wavelength range, no changes to the signal are currently identified at t11 and t12, t13 and t14, but only at t15 if the entire coin 10 has passed the light barrier L2, as the material of the central ring does not allow the infrared light to pass. This is revealed from the graph of FIG. 3(a) at the bottom. FIG. 3(b) shows the process when a coin with a material of the central ring that is transparent to infrared light is tested. It may be seen that the same signal sequences are then produced for the light barriers L1 and L2. Thus, this is an effective discriminating feature for identifying coins provided with a counterfeit material for the central ring.

(12) FIG. 3(c) shows the signal sequence for the two light barriers L1 and L2 both for a conventional bicolour coin and for coins provided with a central ring, where the material for the central ring is not transparent to both visible light and invisible light.

(13) As a whole, the following security features are able to be identified:

(14) Material of the central ring which is transparent to visible light;

(15) Material where infrared light is blocked;

(16) Widths of the outer ring to the left and right;

(17) Width of the material of the central ring to the left and right; and

(18) Core diameter.

(19) In FIG. 4 four light barriers respectively consisting of one optical transmitter and one optical receiver which are identified by 11 and 12, or respectively 11 and 12, are arranged one above the other at a distance h, and respectively h, from the coin running track 20 and at a distance a from one another. If a standard coin of smaller diameter moves through the light barriers 11 and 12, a signal sequence t1 and t2 is produced. For a coin of larger diameter, similar signal sequences are also produced by the light paths 11 and 12. However, if the light barriers are located level with a central ring according to FIG. 1A or 1B, similar signal sequences for 11 and 12 and 11 and 12 may be produced once again, as have been described in connection with FIG. 3.

(20) In FIG. 5 a principal plate 30 and a pivoting plate 32 are shown, wherein said pivoting plate 32 forms the coin running track 20. An LED 34 is incorporated in the pivoting plate 32, said LED 34 passing light through the coin 10 when it moves along the running track 20 past the LED 34. A phototransistor 36 is arranged in the principal plate 30, said phototransistor 36 cooperating with an optical element 38 that produces the effect of a lens and having a portion 40 with a small diameter protruding into a recess 42 of the principal plate 30. The optical element 38 receives the light produced by the LED 34 provided it is either not blocked by the coin 10 or is allowed through by a region of the coin 10 as is the case in connection with the above-described figures.

(21) Instead of a receiver at one point for the light of the LED 34, a line sensor or surface sensor may also be provided in a vertical and or horizontal arrangement as is shown by sensor 44 or respectively by sensor 46 in FIG. 6. In FIG. 7, the sensor 46 is shown in a horizontal arrangement through which light is passed by the LED 34 over the entire width of sensor 46 in order to receive light from the LED 34, which is either not blocked by the coin 10 or is allowed to pass therethrough.