The present invention relates to an ultrasonic sensor for detecting double sheets and a method of detecting double sheets using the same, in which in configuring the ultrasonic sensor for detecting double sheets of banknotes passing through a transfer path, the ultrasonic sensor is configured to include an ultrasonic wave generator and an ultrasonic wave receiver provided in pair to face each other in a direction perpendicular to a transfer direction of the banknotes with the transfer path for transferring the banknotes interposed therebetween, and periodicity of a reception signal detected by the ultrasonic wave receiver is determined to detect whether a zero sheet, a single sheet or double sheets of the banknotes pass through the transfer path according to generation or not of the periodic signal and/or a frequency of the generation.

A dynamic photometric stereo inspection technique usable to capture and analyse the topography of a moving surface. The technique includes an enhanced data capture method and apparatus comprising a spaced array of at least two coplanar illuminates to improve measurement range and accuracy. The apparatus can be used to inspect banknotes, e.g. to assist with fitness assessment and/or forgery detection. The method may comprise automatically assessing surface topography data to provide qualitative and quantitative information about 2D and 3D features, such as changes in reflectivity, colour, glossiness, 3D texture and the surface profile of the surface under inspection.

There is described a method for examining a value document while employing a digital image of the value document which comprises pixels, wherein the image is examined for the presence of at least one irregularity relating to a pre-specified property of the value document, when such an irregularity is found an examination region representing the irregularity is fixed in dependence on the size and/or position and/or form of the irregularity in the image, and for checking the irregularity only a part of those pixels of the digital image that correspond to the examination region is employed.

A paper sheet handling apparatus includes: a displacement amount detector that includes a pressing part intended to press a paper sheet against a transporting face of a paper sheet transporting path and having an initial position at which the pressing part is not in contact with the transporting face of the paper sheet transporting path, the displacement amount detector detecting a displacement amount of displacement of the pressing part from the initial position in a direction perpendicular to the transporting face, the pressing part being displaced according to a thickness of a paper sheet passing between the transporting face and the pressing part; a reference displacement amount storage; a paper sheet thickness storage; and a tape thickness threshold storage.

A multifeed detection device according to the present disclosure includes: a light source configured to irradiate a sheet with light; a light receiver configured to receive transmission light transmitted through a sheet and reflection light reflected by a sheet; and a controller configured to acquire, from the light receiver, transmission output data that is output data of the transmission light and reflection output data that is output data of the reflection light, the controller being configured to determine whether or not a multifeed of sheets has occurred based on the transmission output data and the reflection output data.

A multifeed detection device according to the present disclosure includes: a light source configured to irradiate a sheet with light; a light receiver configured to receive transmission light transmitted through a sheet and reflection light reflected by a sheet; and a controller configured to acquire, from the light receiver, transmission output data that is output data of the transmission light and reflection output data that is output data of the reflection light, the controller being configured to determine whether or not a multifeed of sheets has occurred based on the transmission output data and the reflection output data.