A detector ( 10 ) for detecting an object ( 42 ) in a media item ( 40 ), such as a check or banknote is described. The detector ( 10 ) comprises first electrically conducting means ( 14 ), such as a roller, disposed on one side of a media path ( 32 ); second electrically conducting means ( 16 ), such as another roller, disposed on an opposing side of the media path ( 32 ); insulating means ( 30 a,b ) for electrically insulating the first and second conducting means ( 14,16 ); and impedance measuring means ( 38 ) for measuring the impedance between the first and second electrically conducting means ( 14,16 ). By measuring the impedance between the conducting means ( 14,16 ) it is possible to determine if an electrically conducting object ( 42 ) is being carried by a media item ( 40 ).
1. A detector for detecting an object in a media item, the detector comprising:
a first electrical conducting member disposed on one side of a media path;
a second electrical conducting member disposed on an opposite side of the media path;
a first insulating member which is other than a media item and which is disposed on one end portion of the first electrical conducting member to electrically isolate the first and second electrical conducting members;
a second insulating member which is other than a media item and which is disposed on an opposite end portion of the first electrical conducting member to electrically isolate the first and second electrical conducting members; and
an impedance measuring circuit for measuring impedance at a location which is between the first and second electrical conducting members and between the first and second insulating members to determine if an object is present in the media item as the media item is transported along the media path.
2. A detector according to claim 1 , wherein the first and second electrical conducting members comprise rollers.
3. A detector according to claim 1 , further comprising urging means for biasing the first and second electrical conducting towards each other.
4. A detector according to claim 1 , wherein the first and second electrical conducting members are disposed so that the first and second electrical conducting members are in contact with the media item when the media item passes between the first and second electrical conducting members and between the first and second insulating members.
5. A self-service terminal comprising:
means for receiving a single sheet media item deposited by a self-service customer conducting a self-service transaction;
means defining a media item path along which the deposited single sheet media item can be transported;
a first electrical conductor disposed on one side of the media item path;
a second electrical conductor disposed on an opposite side of the media item path;
a pair of insulating discs mounted on one of the first and second electrical conductors and for electrically isolating the first and second electrical conductors; and
impedance measuring means for measuring impedance between the first and second electrical conductors to determine if an object is present in the deposited single sheet media item being transported along the media item path.
6. A self-service terminal according to claim 5 , wherein each of the first and second electrical conductors comprises a number of rollers.
7. A self-service terminal according to claim 5 , further comprising urging means for biasing the first and second electrical conductors towards each other.
8. A detector according to claim 1 , wherein each of the first and second insulating members comprises elastomeric material.
9. A self-service terminal according to claim 6 , wherein the first and second electrical conductors are disposed so that the first and second electrical conductors are in contact with the single sheet media item as the single sheet media item passes between the first and second electrical conductors and between the pair of insulating discs along the media item path.
10. A self-service terminal according to claim 6 , wherein the impedance measuring means includes means for attempting to pass a current between the first and second electrical conductors.
11. A self-service terminal according to claim 10 , wherein the impedance measuring means includes means for measuring current flow between the first and second electrical conductors when current is attempted to be passed between the first and second electrical conductors.
12. A self-service terminal according to claim 11 , further comprising means for indicating the presence of an object in the single sheet media item when current flow between the first and second electrical conductors is detected.