A method (600) for detecting and tracking a feature of a web of packaging material (102), using a first capacitor (106) placed at a distance (d) from the web of packaging material (102) is provided. The method (600) comprises; feeding (602) a section of the web of packaging material (102) to a first position (p), so that the section influences a dielectric property of the first capacitor (106), measuring (604), at a point of time (t), a capacitance of the first capacitor (106), and determining (612) the feature of the section passing the first capacitor (106) at the point of time (t), based on the capacitance.

Embodiments disclosed herein include a sensor wafer. In an embodiment, the sensor wafer comprises a substrate, wherein the substrate comprises a first surface and a second surface opposite the first surface. In an embodiment, the sensor wafer further comprises a first conductive pad with a first surface area, wherein the first conductive pad has a surface that is substantially coplanar with the first surface of the substrate. In an embodiment, the sensor wafer further comprises a second conductive pad with a second surface area that is smaller than the first surface area, wherein the second conductive pad has a surface that is substantially coplanar with the first surface of the substrate.

Embodiments disclosed herein include a sensor wafer. In an embodiment, the sensor wafer comprises a substrate, wherein the substrate comprises a first surface, a second surface opposite the first surface, and an edge surface between the first surface and the second surface. In an embodiment, the sensor wafer further comprises a plurality of sensor regions formed along the edge surface, wherein each sensor region comprises a self-referencing capacitive sensor.

A sheet conveying apparatus capable of conveying a sheet as a conveyance target in a conveyance path includes a detector that detects capacitance in a predetermined detection region in the conveyance path; and a basis weight identifier that identifies a basis weight of the sheet as the conveyance target on the basis of first capacitance detected by the detector while the sheet as the conveyance target does not pass through the detection region and second capacitance detected by the detector while the sheet as the conveyance target passes through the detection region.

An apparatus for measuring thickness and/or basis weight of a web or film has a frame defining a measurement channel between two opposing frame faces. A first sensor component is on or appended to the first face and a second sensor component is on or appended to the second face of the frame. A series of rollers guide the web or film into the measurement channel in an overlapping relation such that at least two portions of said web reside in said measurement channel for detection by the sensor. The frame may be a C-frame gauge, and the sensor may be two capacitor plates. One sensor component is a source, while the opposing sensor component is sensitive to the source emission. The combined thickness of the portions of the web residing in the measurement channel is determined based upon the degree to which the web or film attenuates the emission.

A device for detecting a foreign object attached on a surface of a sheet-like medium, comprising a static electricity providing part (A) for providing static electrical charges, a medium transporting part (B) for transporting a medium under detection, and a static electricity sensor and identifier part (C). The medium transporting part comprises a static electricity receiving unit and a static electricity absorbing unit sequentially connected. The static electricity receiving unit is connected to the static electricity providing part (A), and the static electricity absorbing unit is connected to the static electricity sensor and identifier part (C). The static electricity receiving unit is configured to transfer the static electrical charges obtained from the static electricity providing part (A) to the medium under detection. The static electricity absorbing unit is configured to absorb the static electrical charges of the medium under detection.

A sheet conveying apparatus capable of conveying a sheet as a conveyance target in a conveyance path includes a detector that detects capacitance in a predetermined detection region in the conveyance path; and a basis weight identifier that identifies a basis weight of the sheet as the conveyance target on the basis of first capacitance detected by the detector while the sheet as the conveyance target does not pass through the detection region and second capacitance detected by the detector while the sheet as the conveyance target passes through the detection region.

A device for detecting a foreign object attached on a surface of a sheet-like medium, comprising a static electricity providing part (A) for providing static electrical charges, a medium transporting part (B) for transporting a medium under detection, and a static electricity sensor and identifier part (C). The medium transporting part comprises a static electricity receiving unit and a static electricity absorbing unit sequentially connected. The static electricity receiving unit is connected to the static electricity providing part (A), and the static electricity absorbing unit is connected to the static electricity sensor and identifier part (C). The static electricity receiving unit is configured to transfer the static electrical charges obtained from the static electricity providing part (A) to the medium under detection. The static electricity absorbing unit is configured to absorb the static electrical charges of the medium under detection.

A method is described for measuring, in a multi-layer film obtained by blow extrusion process and formed by one or more layers of a first material and a second material, the total thickness of the first material and/or the second material. The method includes the steps of: a) acquiring by means of an X-ray sensor a first measurement signal representative of the total thickness of the film; b) acquiring by means of a capacitive sensor a second measurement signal which is the sum of the signals given by the first and second materials of the film. The signal given by each material of the film is a function of the thickness of the material; and c) calculating, from the first and second signals, the total thickness (L.sub.1 of the first material and/or the total thickness (L.sub.2) of the second material.

A method for determining container properties, wherein a container to be examined is transported along a predetermined transport path, and this container has a bottom region, a main body which serves to receive a filling material, and an mouth region, and wherein this container is formed at least in part of a material containing paper or cardboard. At least one wall of the container is arranged between two electrodes, and an electrical voltage or an alternating electrical field is applied to the electrodes, and at least one electrical parameter is determined which is characteristic of an electrical field which is built up between electrodes, and from this electrical parameter, at least one parameter characteristic of the container is determined.