GB2342750A

GB2342750A - Token validating apparatus

Info

Publication number: GB2342750A
Application number: GB9821794A
Authority: GB
Inventors: Ezio Panzeri
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-10-06
Filing date: 1998-10-06
Publication date: 2000-04-19
Also published as: GB9821794D0

Abstract

Apparatus for validating a token comprises; a token guide for guiding a token along a predetermined path, a light source 10 for generating a beam of light, a light detector 18, 20 for detecting where the beam of light is intercepted by a token passing along the predetermined path and an integrally formed lens and prism 6. The integrally formed lens and prism 6 receives the beam of light and forms a first collimated beam in a first direction traversing the predetermined path, and the prism section of the arrangement receives a portion of the collimated beam internally reflecting it to form a second collimated beam (16 Figure 4) in a second direction traversing the predetermined path in a substantially perpendicular direction. The integrally formed lens and prism 6 may be formed from transparent plastics furane or polymethylmethacrilate, and can have a second lens surface that is substantially flat. The token guide may be positioned so that a major face of a planar token is substantially perpendicular to the first collimated beam. The token guide and the integrally formed lens and prism 6 may be enclosed in a housing formed from opaque moulded plastics. The light detector may be a CMOS linear array 18, 20. The light source may be a laser diode 10 fixed to the housing 22. Apparatus for validating a token may comprise, a light source, an integrally formed housing 22 and token guide 24 formed of moulded plastics, the housing 22 encapsulating a light detector.

Description

TOKEN VALIDATING APPARATUS This invention relates to the field of systems for validating tokens, such as coins.

It is known to provide token validating systems, such as that described in PCT Published Patent Application WO-A-97/44760, that use optical sensing to determine the precise dimensions of a token. These precise dimensions then give an indication of which token has been placed through the apparatus.

Token validating systems are typically needed in very high quantities in order to satisfy the various sources of demand, such as vending machines, ticket machines and the like. Accordingly, measures that can reduce the expense and complexity of token validation systems are strongly advantageous.

A further advantageous characteristic of token validating systems is that they should be highly resistant to environmental influences, e. g. if used in an outdoor location that is wet, hot and/or humid, then the validating apparatus must not malfunction.

Viewed from one aspect the present invention provides apparatus for validating a token, said apparatus comprising: a token guide for guiding a token along a predetermined path; a light source for generating a beam of light; a light detector for detecting where said beam of light is intercepted by a token passing along said predetermined path; and an integrally formed lens and prism for receiving said beam at a first lens surface and forming a first collimated beam in a first direction traversing said predetermined path, said prism receiving a portion of said collimated beam and intemally reflecting said portion to form a second collimated beam in a second direction traversing said predetermined path and substantially perpendicular to said first direction.

Providing the lens and the prism in a single integrally formed unit for generating the two perpendicular light beams has a number of advantages associated with it. Firstly, the number of components within the validating apparatus is reduced so reducing the cost of manufacture and the complexity of assembly. Furthermore, integrally forming the lens and the prism reduces the losses in intensity of the light beam due to it moving from one transmission medium (e. g. the lens material) to another light transmission medium (the air). This in turn means that less intense, less expensive and more reliable light sources may be used to achieve reliable and accurate validation. The reduction in the number of surfaces through which the light beam must pass also increases environmental resistance by decreasing the number of surfaces that can be subject to contamination that would block the transmission of the light beam.

The integrally informed lens and prism is particularly well suited for use in a validating system as set out above and is able to produce a desired output of two collimated and substantially perpendicular light beams using only a relatively few and simple optical elements.

It will be appreciated that the surfaces of the integrally formed lens and prism could have many different forms and shapes for achieving collimation of the first light beam, but it is preferred that the second lens surface is substantially flat.

A substantially flat second lens surface is well suited to allow the integrally formed lens and prism to be placed close to the token guide such that the predetermined path the token follows will intercept both the first collimated beam and the second collimated beam substantially simultaneously as it passes. Furthermore, having the token pass close by the second lens surface reduces the likelihood of foreign bodies causing a problem by blocking the optical path between the second lens surface and the token.

The tokens being validated could have many different shapes. However, it will be appreciated that a large majority of tokens that one would wish to validate are substantially plainer in shape (e. g. circular discs) and accordingly embodiments in which the first collimated beam and the second collimated beam are substantially perpendicular to one another with the major plane of the token perpendicular to the first collimated beam and parallel to the second lens surface are particularly convenient.

The integrally formed lens and prism could be formed of various different materials providing they had the appropriate transmission characteristics and refractive index. However, the invention is particularly well suited to embodiments in which the integrally formed lens and prism is formed of molded plastics. Molded plastics are well suited to mass producing optical elements of a suitable accuracy and with relatively complex shapes such as that involved in the present invention.

Whilst many different plastics materials may be used, a particularly environmentally resistant and suitable plastics materials is one of furane and polymethylmethacrilate.

Environmental resistance (e. g. antifog, humidity resistance) may be improved and manufacturing cost reduced in embodiments in which a housing encloses said token guide and said integrally formed lens and prism, said housing, said token guide and said integrally formed lens and prism are all integrally formed of molded plastics.

Electronic components can be particularly vulnerable to environmental malfunctions and so preferred embodiments of the invention encapsulate the light detector within the molded plastics. It has been found that light detectors, and especially CMOS linear array sensors, are able to withstand the temperatures involved in molded plastics for the required cooling down periods.

The performance of the validation apparatus can be improved by making the housing from opaque plastics whilst the integrally formed lens and prism is formed of transparent plastics.

The use of opaque plastics for the housing ensures that light from the light source does not escape and also reduces the possibility of externally generated light influencing the light sensors and causing malfunctions.

It has been found convenient that the light source should be fixed to the housing after the housing has been formed. This is particularly the case when the light source is a laser diode. Presently available light sources are not well suited to withstanding the high temperatures that may be involved in encapsulation whilst also providing the other features of a highly compact form and an intense light output.

New light sources with greater temperature resistance may be encapsulated to improve environmental resistance.

The tokens being validated could have many different forms as mentioned above. However, it will be appreciated that the invention is particularly well suited to validating tokens which are coins.

Viewed from another aspect the present invention provides apparatus for validating a token, said apparatus comprising: a housing; a token guide within said housing for guiding a token along a predetermined path; a light source for generating a beam of light; and a light detector for detecting where said beam of light is intercepted by a token passing along said predetermined path; wherein said housing and said token guide are integrally formed of molded plastics and said light detector in encapsulated within said housing.

The encapsulation of the light detector within an integrally formed housing and token guide has the strong advantage of providing an improved level of environmental resistance and simplifying construction and assembly costs.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings: Figure 1 schematically illustrates and integrally formed lens and prism; Figure 2 shows a possible cylindrical, aspherical profile for the first lens surface; Figure 3 illustrates a mathematical representation of the shape of the first lens surface; Figure 4 illustrates the reduced and balanced transmission loses given by the integrally formed lens and prism; Figure 5 illustrates the paths of the light beam through the integrally formed lens and prism; Figure 6 illustrates the relative dispositions of the light source, optical elements and light detectors within the validating system; Figure 7 is similar to that of Figure 6, but in this case also shows a cut-away section of the housing; Figure 8 is a plan view of Figure 7; and Figure 9 is a perspective exploded view of the light source and sensing portion of a token validating system.

Figure 1 shows in the left hand portion how the functions being performed by the integrally formed lens and prism unit are similar to those that would be performed by a separate lens 2 and prism 4. When these are combined as a single integrally formed lens and prism as shown in the right hand portion of Figure 1, then the optical paths are substantially unaltered. What does alter is the number of times the light must pass from one transmission medium to another and accordingly the transmission loses and risks of surface contamination are reduced.

Figure 2 shows an example of the lens profile that may be used for the first lens surface 8 of the integrally formed lens and prism 6. The first lens surface shape shown in such that light diverging from a point light source a suitable distance from the lens is collimated into a first collimated light beam that passes substantially perpendicularly through the second lens surface 10, which is substantially flat.

Figure 3 illustrates the mathematical equation giving the shape of the first lens surface illustrated in Figure 2. Other shapes are possible, e. g. cylindrical.

Figure 4 is similar to Figure 1, but in this case shows the transmission losses.

Assuming that each time the light passes between air and the polymethylmethacrilate of the optical elements it is subject to a 4% loss in intensity, then the separate elements illustrated in the left hand size of Figure 4 would result in an 8% loss in intensity for the first collimated beam and a 16% loss in intensity for the second collimated beam. In contrast to this, the integrally formed lens and prism produces an 8% loss in intensity for both the first collimated beam and the second collimated beam. This has the advantage that the intensity of the light source does not have to be unduly increased to compensate for what otherwise would be the weaker of the beams, i. e. the second collimated beam. Furthermore, a balance in the intensities between the two collimated light beams means that the light intensity of a single light source may be chosen to the value that best suits the light detectors that respond to both of the light beams.

Figure 5 illustrates the path of the light beams passing through the combined lens and prism. A light source 10 generates a divergent beam that is formed into a fan shaped beam by the optical element 12. This fan shaped beam is then incident upon the combined lens and prism 6. The first lens surface 8 collimates the beam. The portion of the collimated beam that passes into the prism section of the combined lens and prism 6 is subject to total internal reflection at the prism surface 14 to form the second collimated beam 16. The light paths through the combined lens and prism unit 6 are also shown in plan view at the bottom of Figure 5.

Figure 6 shows the relative dispositions of the light source 10 in the form of a laser diode, the optical element 12, the combined lens and prism 6 and two light detectors 18,20. The light detectors are CMOS linear array sensors.

Figure 7 is similar to Figure 6, but in this way showing part of the housing 22 in cut-away form. In practice, the housing 22 is composed of opaque polymethylmethacrilate that is integrally formed in a molding process with the transparent polymethylmethacrilate that forms the lens and prism unit 6 and the optical element 12. The light detectors 18,20 are also embedded within this housing 22. The plastics material is typically heated to 240 C for the molding process and the light detectors 18,20 have a resistance to such temperatures of approximately 10 seconds, which is sufficient to allow the plastics to cool below a temperature at which they would otherwise damage the light sensors 18,20.

Figure 8 is a plan view of the arrangement of Figure 7.

Figure 9 is an exploded perspective view of the light detecting portion of the validating system. The signal processing portion may be similar to that described in PCT Published Patent Application WO-A-97/44760.

The housing 22 includes a coin guide slot 24 through which a coin (token) to be validated is passed. When the coin passes through the coin guide it follows a predetermined path in front of the light detectors 18,20 and interrupts the light beams produced by the lens and prism unit 6 that are incident upon the light detectors 18,20.

The high speed sensing performed by the light detectors 18,20 allows a series of measurements to be made that when analyzed are characteristic of a particular token.

The laser diode 10 that serves as the light source is fixed to the housing 22 as a separate operation after the housing and optical components have been integrally formed by injection plastics molding. The laser diode 10 would be unable to withstand the molten temperatures of the plastics material from which the housing 22 is formed.

Claims

CLAIMS 1. Apparatus for validating a token, said apparatus comprising: a token guide for guiding a token along a predetermined path; a light source for generating a beam of light; a light detector for detecting where said beam of light is intercepted by a token passing along said predetermined path; and an integrally formed lens and prism for receiving said beam at a first lens surface and forming a first collimated beam in a first direction traversing said predetermined path, said prism receiving a portion of said collimated beam and internally reflecting said portion to form a second collimated beam in a second direction traversing said predetermined path and substantially perpendicular to said first direction.
2. Apparatus as claimed in claim 1, wherein said integrally formed lens and prism has a second lens surface that is substantially flat.
3. Apparatus as claimed in claim 2, wherein said first collimated beam is substantially perpendicular to said second lens surface.
4. Apparatus as claimed in any one of the preceding claims, wherein said token guide is disposed such that said predetermined path leads a substantially planar token to pass intercept said beam of light with its major plane substantially perpendicular to said first collimated beam and its edge substantially perpendicular to said second collimated beam.
5. Apparatus as claimed in any one of the preceding claims, wherein said integrally formed lens and prism is formed of molded plastics.
6. Apparatus as claimed in claim 5, wherein said molded plastics is one of fuiane and polymethylmethacrilate.
7. Apparatus as claimed in any one of the preceding claims, wherein a housing encloses said token guide and said integrally formed lens and prism, said housing, said token guide and said integrally formed lens and prism all being integrally formed of molded plastics.
8. Apparatus as claimed in claim 7, wherein said light detector is encapsulated within said molded plastics.
9. Apparatus as claimed in claim 8, wherein said light detector is a CMOS linear array sensor.
10. Apparatus as claimed in any one of claims 7,8 and 9, wherein said housing is formed of opaque plastics and said integrally formed lens and prism is formed of transparent plastics.
11. Apparatus as claimed in any one of claims 7 to 10, wherein said light source is fixed to said housing after said housing has been formed.
12. Apparatus as claimed in claim 11, wherein said light source is a laser diode.
13. Apparatus as claimed in any one of the preceding claims, wherein said token is a coin.
14. Apparatus for validating a token, said apparatus comprising: a housing; a token guide within said housing for guiding a token along a predetermined path; a light source for generating a beam of light; and a light detector for detecting where said beam of light is intercepted by a token passing along said predetermined path; wherein said housing and said token guide are integrally formed of molded plastics and said light detector in encapsulated within said housing.
15. Apparatus as claimed in claim 14, wherein said molded plastics is polymethylmethacrilate.
16. Apparatus as claimed in any one of claims 14 and 15, wherein said light detector is a CMOS linear array sensor.
17. Apparatus as claimed in any one of claims 14,15 and 16, wherein said housing is formed of opaque plastics.
18. Apparatus as claimed in any one of claims 14 to 17, wherein said light source is fixed to said housing after said housing has been formed.
19. Apparatus as claimed in claim 18, wherein said light source is a laser diode.
20. Apparatus as claimed in any one of claims 14 to 19, wherein said token is a coin.
21. Apparatus for validating a token substantially as hereinbefore described with reference to the accompanying drawings.