Patent ID: 8684156

Claim:
A bill acceptor comprising: a housing comprising a face panel defining a bill slot for the insertion of a bill; a bill-receiving unit accommodated in said housing, said bill-receiving unit comprising a holder base defining therein a bill passage in communication with said bill slot, a control module, a transmission mechanism controllable by said control module to transfer an inserted bill, and a recognition circuit assembly mounted in opposing top and bottom sides of said bill passage, said recognition circuit assembly comprising a sampling and validating module consisting of a plurality of light emitters and light sensors and controllable by said control module to validate the authenticity and face value of an inserted bill; and at least one privacy filter mounted in a light path in said bill-receiving unit between said bill passage and said light sensors to filtrate external light sources and to let the light emitted by said light emitters pass toward said light sensors, said at least one privacy filter comprising a multilayer filter made of blind ultra-fine optical technology configured to allow only light emitted by the plurality of light emitters to pass through the bill passage at an angle of 90Â° or 60Â°Â±5Â°.