A method and a sensor for checking documents are provided in which the same detector is used for a remission measurement and a luminescence measurement of the value document. The remission measurement value being detected during the illumination of the value document with an excitation light used for luminescence excitation, and the luminescence measurement value after switching off the illumination. In order to reduce a distortion of the remission measurement value by the luminescence, a spectral detection filter is incorporated into the detection ray path, which has a transmission of at least 0.5% in the spectral region of the excitation light. The increased transmission of the spectral detection filter achieves that the excitation intensity impinging on the detector far exceeds the luminescence intensity occurring simultaneously with the excitation and thus reduces the mentioned distortion.

A method and a sensor for checking documents are provided in which the same detector is used for a remission measurement and a luminescence measurement of the value document. The remission measurement value being detected during the illumination of the value document with an excitation light used for luminescence excitation, and the luminescence measurement value after switching off the illumination. In order to reduce a distortion of the remission measurement value by the luminescence, a spectral detection filter is incorporated into the detection ray path, which has a transmission of at least 0.5% in the spectral region of the excitation light. The increased transmission of the spectral detection filter achieves that the excitation intensity impinging on the detector far exceeds the luminescence intensity occurring simultaneously with the excitation and thus reduces the mentioned distortion.

A light detection sensor includes a light source that irradiates a detection target with light, a rod lens that collects emitted light from the detection target, a first light receiving element that detects the emitted light that has passed through the rod lens, and a second light receiving element that detects the emitted light that has passed through the rod lens, at a position different from a position at which the first light receiving element detects the light.

Provided is a banknote sorter. A light source unit obliquely illuminates light at a designated angle onto a surface of a banknote when the banknote is being transferred through the banknote sorter by a driving means. A light sensor unit is placed to sense the light that is irradiated at the designated angle onto the surface of the banknote and/or tape, reflected from the surface of the banknote and/or the tape, and is incident onto the light sensor unit at an angle different from the designated angle. A control unit controls the light source unit, processes sensing information from the light sensor unit, and discriminates any tape on the banknote.

A payment card includes hidden features (e.g., textual messages, graphics, emphasis features associated with conspicuous features of the payment card, or the like) undiscernible under only visible light, but discernable under ultraviolet light. The hidden features can be incorporated into multiple layers of a side of the payment card and can be present with different transparencies, different colors, and different persistence.

A method for checking value documents involves the steps of: irradiating, by an excitation device, a first side of the value document with excitation radiation for exciting luminescence of a luminescent substance on the value document, such that the first side is a back side of the value document, capturing luminescence radiation which was excited by excitation of the luminescent substance at a front side of the value document by at least a part of the excitation radiation after transmission through the substrate of the value document and exits the value document at least partly at the back side of the value document after transmission through the value document, by a capture device, and checking the value document in dependence on at least one property of the captured luminescence radiation by means of an evaluation device.

A method for checking value documents involves the steps of: irradiating, by an excitation device, a first side of the value document with excitation radiation for exciting luminescence of a luminescent substance on the value document, such that the first side is a back side of the value document, capturing luminescence radiation which was excited by excitation of the luminescent substance at a front side of the value document by at least a part of the excitation radiation after transmission through the substrate of the value document and exits the value document at least partly at the back side of the value document after transmission through the value document, by a capture device, and checking the value document in dependence on at least one property of the captured luminescence radiation by means of an evaluation device.

A light source driver circuit has a switching regulator including a voltage input, a voltage output, and a regulation input; a current source with a switching element and a voltage-controllable member arranged in series with the light source load. A pulse signal is applied to a control terminal of the switching element to connect, in a first switching state of the switching element, a control terminal of the voltage-controllable member to a voltage source and in a second switching state of the switching element not to connect the control terminal of the voltage-controllable member to the voltage source; and a regulation unit. An optical measuring instrument includes a light source driver circuit, a device checks value documents with the light source driver circuit, and a method is provided for operating a light source load with the light source driver circuit.

A light source driver circuit has a switching regulator including a voltage input, a voltage output, and a regulation input; a current source with a switching element and a voltage-controllable member arranged in series with the light source load. A pulse signal is applied to a control terminal of the switching element to connect, in a first switching state of the switching element, a control terminal of the voltage-controllable member to a voltage source and in a second switching state of the switching element not to connect the control terminal of the voltage-controllable member to the voltage source; and a regulation unit. An optical measuring instrument includes a light source driver circuit, a device checks value documents with the light source driver circuit, and a method is provided for operating a light source load with the light source driver circuit.

A payment card includes hidden features (e.g., textual messages, graphics, emphasis features associated with conspicuous features of the payment card, or the like) undiscernible under only visible light, but discernable under ultraviolet light. The hidden features can be incorporated into multiple layers of a side of the payment card and can be present at different transparencies. The hidden features, applied during manufacturing, can be i) selected (e.g., randomly or sequentially) from an available hidden features list; ii) supplied by user input; and/or iii) selected based on a user's previous hidden feature(s) (e.g., the same as or different from the previous hidden feature). A quality check can include comparing an image of the payment card illuminated under ultraviolet light with the selected hidden feature(s).