Abstract: A document verification device detects the presence of a metal security thread embedded in a document such as currency paper. The device includes a sensor pad arrangement and corresponding signal processing electronics. The arrangement includes a single central sensing pad flanked by an array of twenty-seven pairs of outer pads. Each pair of outer pads in the array is electrically connected together. Every pad is made of conductive material. The width dimension of each outer pad in the array is greater than the width of the security thread. Each outer pad in the array is preferably angled to improve the reliability of detection of the security thread.

Abstract: Capacitive water height gauge and method in which a pair of electrically conductive plates are positioned side-by-side to form a capacitor having a capacitance which is dependent upon the dielectric properties of materials in a region above the plates. The plates are positioned beneath the body of water so that the capacitance is dependent upon the amount of water in the region above the plates, and that capacitance is monitored to determine the height of the water above the plates.

Abstract: In accordance with a first aspect of the present invention, the sensitivity of a magnetically modulated AC-AFM is substantially improved by the use of a ferrite-core solenoid for modulating the magnetic cantilever of the ACAFM. In accordance with a second aspect of the present invention, the detection system for a magnetically modulated AC-AFM incorporates AC coupling of the signal from the position sensitive detector/beam deflection detector in order to remove the DC component of the signal, resulting in significantly improved dynamic range over systems utilizing DC coupling. High frequency modulation signals are detected through the use of fast analog multipliers which, after active filtering, give a low frequency signal which may be processed by digital electronics. In accordance with a third aspect of the present invention, operation of the microscope at small amplitudes of oscillation leaves small asperities on the tip intact and results in dramatic improvement in resolution.

Abstract: A security thread for documents such as currency and banknote paper comprises a plastic substrate coated with a plurality of discrete metallic patterns of electrically-conductive material, such as aluminum. The metallic patterns are arranged on the surface of the thread to indicate the particular denomination of the currency paper. The thread is typically embedded entirely with the currency paper. A first embodiment of a verification device determines the authenticity and denomination of the currency paper by counting the number of conductive metallic patterns on the thread and comparing the count to various count ranges. A second embodiment of the verification device scans the thread in a narrow-edge direction such that it simultaneously encounters all of the conductive thread segments. Capacitive coupling of an oscillator signal into one or more sensing pads result in an electrical signal having a distinct pattern.

Abstract: A photodiode and a phototransistor are positioned on opposite sides of a document subjected to verification for authenticity under transmitted light. A logic circuit determines the presence or absence of the security feature and correspondingly provides visual or audible indication thereof. The photodiode, phototransistor and related circuitry are arranged within an enclosure that is attached to a currency receiving device such as a cash register. The visual or audible indicators are mounted on the cash register for immediate indication of the currency verification to the cashier. A simplified capacitive proximity sensor can be employed, per se, for inexpensive applications or for redundant verification in combination with an optical detector. The shape of the capacitive sensor is configured to that of the security thread to discriminate between the security thread and the currency paper. Additional optical circuits are employed to detect counterfeit markings on the currency surface.

Abstract: A currency paper has a security thread embedded therein. The thread comprises a plastic substrate having a plurality of alphanumeric, metallic, electrically-conductive characters formed thereon. The characters have predetermined heights and widths and spacings therebetween. The verification device comprises an oscillator electrode and associated horizontal and vertical electrodes. A time-varying oscillator signal is coupled to the oscillator electrode. The spacing of the horizontal and vertical electrodes in relation to the oscillator electrode is determined by the spacing between the metallized characters on the thread. A valid security thread capacitively couples the oscillator signal into the horizontal electrode but not the vertical electrode. On the other hand, a counterfeit security thread will couple the oscillator signal into both the horizontal and vertical electrodes. Signal processing electronics is provided to sense these valid and counterfeit conditions.

Abstract: A verification device for a security thread embedded within currency paper includes two or more sensor channels, each channel comprising a sensor plate and a guard plate disposed adjacent to one another. The sensor plate and guard plate of one channel are in a planar relationship with the sensor plate and guard plate of all other channels. A transistor has its base connected to the sensor plate and its emitter connected to the guard plate, thereby effectively removing any stray capacitance between the sensor and guard plates. The output of the transistor at its emitter is indicative of the amount of the electrical charge on the sensor plate. Signal processing electronics disposed after the transistor convert the sensor plate capacitance into an electrical signal whose pulse width is proportional to the amount of sensor plate capacitance. A valid currency having a security thread embedded therein passes by a sensor plate and varies the amount of capacitance of the plate.

Abstract: A verification device for a security thread embedded within currency paper includes a pair of capacitive plates having applied thereto time-varying electronic signals that are 180.degree. out of phase. Disposed between the plates is a sensor element comprising a cylindrical wire dimensionally equal to the security thread. A guard electrode surrounds the sensor; the guard, sensor, and plates comprising a capacitance bridge. When the security thread in the currency is adjacent to the sensor and in proximity thereto, a capacitance imbalance occurs in the bridge. Electronic circuitry is responsive to this imbalance and provides an indication of a valid security thread embedded within the proffered currency paper.

Abstract: A photodiode and a phototransistor are positioned on opposite sides of a document subjected to verification for authenticity under transmitted light. A logic circuit determines the presence or absence of the security feature and correspondingly provides visual or audible indication thereof. The photodiode, phototransistor and related circuitry are arranged within an enclosure that is attached to a currency receiving device such as a cash register. The visual or audible indicators are mounted on the cash register for immediate indication of the currency verification to the cashier. A simplified capacitive proximity sensor can be employed, per se, for inexpensive applications or for redundant verification in combination with an optical detector. The shape of the capacitive sensor is configured to that of the security thread to discriminate between the security thread and the currency paper. Additional optical circuits are employed to detect counterfeit markings on the currency surface.

Abstract: A security thread detector for verifying the authenticity of banknotes. In the preferred embodiment, the invention comprises a housing with a passage through which banknotes can be passed, wherein the housing also comprises a waveguide, a microwave oscillator for generating microwaves and two resonating slots on a wall of the waveguide, and a microwave detector. After a banknote is inserted through the passageway, the microwave diode produces an analog signal that is proportional to the microwave strength. The diode and the slots are arranged such that the radiated power from each slot is one hundred eighty degrees out-of-phase. If a banknote has no security thread, then the detector receives a balanced signal. If the banknote contains a security thread, the thread interferes with one of the radiating slots. This interference causes an imbalance condition and a corresponding signal is sent from the detector diode. The resulting signal is then sent to a microprocessor which activates an appropriate indicator.

Abstract: A method and apparatus for generating in real time full width formation profiles of a web of material which passes between a light source and a camera which generates signals corresponding to the light intensity across the entire width of the web as compared to single point or sample measurements. These signals are then processed to generate in real time at a full width formation profile of the web.

Abstract: Precision traveling optical table assembly having a rigid support framework and a rigid rectangular framework. The rigid rectangular framework is supported at three locations upon the rigid support framework. The rectangular framework includes a pair of spaced parallel rails. An optical table is provided. Carriages are mounted upon the pair of rails for longitudinal movement relative to the rails. The optical table is supported at only three locations from the carriages. A drive mechanism is connected between the carriages and the rectangular framework for causing relative movement between the optical table and the rectangular framework. At least one optical element is carried by the optical table.

Abstract: Optical scanning apparatus including a rotating pyramidal mirror scanning wheel with reflector segments for deflecting a laser beam into and away from a doublet mirror roof reflector associated with said scanning wheel. The scanning wheel introduces components of vertical and horizontal angular deviation into the beam, the vertical deviation component being cancelled by inversion through the roof reflector while the horizontal angular component is doubled upon the second reflection from the scanning wheel so that the output beam is vertically wobble-free and stable while the beam is scanned through the sum of the horizontal angular components introduced by the wheel.

Abstract: Disclosed is an optical read-write system including a first laser scanner for linearly scanning an object and generating a digital signal for the line scan. The digital signal is stored in a buffer at a read clock rate which is correlated to the scan of the first laser scanner. The digital signal is read-out of the buffer at a write clock rate and is applied as a control signal for a second laser scanner which linearly scans an image plane to develop an image. The second scanner scans at the same scan rate and distance as the first scanner, and the size of the image compared to the object size is determined by the differential of the read clock rate and the write clock rate.

Abstract: Gimballed coupling for use with a lead screw and nut assembly having a housing with the nut mounted in the housing and the nut threadedly engaging the lead screw. A transfer plate is provided. A thrust bearing assembly is carried by the transfer plate. First and second bearing members are provided which are disposed between the nut and the thrust bearing assembly. The first bearing member engages the housing and the second bearing member engages the thrust bearing. The first and second bearing members have cooperative spherical surfaces to permit the pivotal movement of the nut with respect to the transfer plate. Means is carried by the transfer plate and the housing for yieldably urging the housing towards the transfer plate. Additional means is provided for preventing rotation of the housing with respect to the transfer plate.

Abstract: Disclosed is a facsimile system having a transmitter for optically scanning input copy to produce modulated electrical signals to be transmitted to a receiver. The receiver responsively controls output optical scanning to form output copy as a reproduction of the input copy. Signal processing in both the transmitter and receiver employs spatial coding. In the transmitter scanner, a spatially coded reference signal, generated by the scanning beam and a spatial mask, is employed. In the receiver scanner, a spatially coded reference signal, generated by the scanning beam and an identical spatial mask is employed also. Therefore, the transmitter and receiver scanners are spatially synchronized without the need for real-time synchronization.