Abstract: A number of bistable magnetic devices are dispersed in a scanning region of a checking object. Each bistable magnetic device is formed of a nonmagnetic material which undergoes a drastic flux reversal attributable to the Large Barkhausen effect when subjected in succession to first and second external magnetic fields of opposite directions. A processing apparatus comprises magnetic generators for generating magnetic fields of opposite directions, a transportation mechanism for moving the checking object at constant speed, and a coil for detecting magnetic pulses, which are generated as the bistable magnetic devices are subjected to the flux reversal, as changes of electromagnetic induction voltage. A detection signal for the scanning region detected by the apparatus is converted into a cipher code and then recorded in a code indicator section of the checking object.

Abstract: A number of bistable magnetic devices are dispersed in a scanning region of a checking object. Each bistable magnetic device is formed of a nonmagnetic material which undergoes a drastic flux reversal attributable to the Large Barkhausen effect when subjected in succession to first and second external magnetic fields of opposite directions. A processing apparatus comprises magnetic generators for generating magnetic fields of opposite directions, a transportation mechanism for moving the checking object at constant speed, and a coil for detecting magnetic pulses, which are generated as the bistable magnetic devices are subjected to the flux reversal, as changes of electromagnetic induction voltage. A detection signal for the scanning region detected by the apparatus is converted into a cipher code and then recorded in a code indicator section of the checking object.

Abstract: Provided is an identification system which is highly effective in identifying the authenticity of an object and extremely difficult to analyze for the purpose of forgery. The object to be identified is affixed with an identification element comprising a reflective layer including a hologram, a diffraction grating or the like, which directs incident light of a prescribed wave length into a plurality of point symmetric directions, and a polarization plane rotating layer which rotates the polarization plane of the light as it passes through the polarization rotating layer. A linearly polarized light is impinged upon the identification element, and is received by a multisegment photodiode arranged in an annular fashion.

Abstract: A number of high-permeability magnetic elements are dispersed in a scanning region of a checking object. A core of a processing apparatus is provided with an exciting coil and a sensor coil. When a bias magnetic field is applied to the core, and the scanning region is passed in the vicinity of a gap, the permeability of the gap varies depending on the density of the magnetic elements, so that a magnetic flux passing through the core changes. A detection signal corresponding to the change of the magnetic flux is detected by means of the sensor coil. This detection signal is converted into a cipher code and then recorded in a code indicator section of the checking object.

Abstract: An object to be checked has a scanning region which contains a large number of magnetic elements scattered at random. Each of the magnetic elements is made up of an element main body formed of a high molecular material, and magnetic metal powder contained in the element main body. A processing apparatus employed for checking whether or not the object is authentic has a magnetic sensor which is made up of a pair of MR elements and a magnet. The MR elements are arranged side by side in the direction in which the scanning region is scanned. In the manufacturing process of the object, a detection signal which is based on variations in the output ratio between the MR elements is produced, with the scanning region of the object being moved. The detection signal is converted into a cipher code, and this cipher code is recorded in a code indicator section.

Abstract: Each identification mark consisting of hologram or diffraction grating having a unique diffractive property which can be detected with optical identification means is formed on a seal, and, by affixing such seals as a combination and reading them, the analysis or forgery of each identification mark is made highly difficult. Since the possible modes of combination and the possible number of combinations can be freely and easily selected, high levels of expandability, identification power and handling facility can be achieved at a relatively low cost. This system can be applied to various articles such as information storage cards including magnetic cards, and keys. By using the system for verifying the authenticity of the article, an effective prevention of the counterfeiting of the article can be achieved.

Abstract: Provided is a system for identifying the authenticity of an article which is reliable, and would not restrict the freedom of design. An identification region is defined on the article for identification purpose. The identification region comprises a light reflecting layer which is adapted to transmit visible light and reflect light of a certain wavelength other outside the visible light band with a certain diffractive property. Therefore, the identification region is hardly visible to human eyes, and this not only discourages an attempt to counterfeit the identification region but also would not affect the external appearance of the article. Further, the visible light which has passed through the reflecting layer and reflected by the surface of the article itself or an underlying layer is prevented from reaching the light detecting device so that spurious noises which may disturb the identification process can be eliminated.

Abstract: For the purpose of identifying the authenticity of an article, an incident detecting light beam having a certain wave length and a polarization plane extending in a certain direction is projected from a light emitting element, and the plane of polarization of this incident light is rotated by 90.degree. as it impinges upon and reflected by an identification region having a specific reflective directivity owing to its diffractive property, and the reflected linearly polarized light is received by a light receiving element which is capable of recognizing the diffractive property via a polarization filter oriented so as to receive only the light having a plane of polarization perpendicular to that of the incident light.

Abstract: An optical identification label consisting of an area of hologram or diffraction grating which is transparent to visible light but reflects incident light with a specific reflective directivity. By identifying the reflectivity directivity, it is possible to identify the authenticity of the label and, hence, the object to which the identification label is affixed. The fact that the identification label is transparent to human eyes offers a strong discouraging effect on potential forgers. Further, the pattern of the reflected light may be used as means for encoding data.

Abstract: An optical head structure, comprising: a light source; an optical system for projecting a first light beam from the light source upon an optical data recording medium and guiding a second light beam produced from the optical data recording medium as a result of projecting the first light beam, as a converging light beam; a light detecting element having at a photoelectric surface area divided into at least three surface parts, consisting of a central band part extending centrally and diametrally across the surface area and a pair of adjoining outer parts which are arranged on either side of the central band part, to receive the second light beam at a position in a path of the second light beam slightly displaced from a focal point of the second light beam; and a subtracter for producing a difference between an output from the central band part and a sum of outputs of the adjoining parts; the central band part being progressively narrower as it extends away from a central part of the photoelectric surface area

Abstract: A screw inspection device of the invention has a screw transfer mechanism for transferring a screw through a predetermined transfer path, a sensor for performing predetermined measurements of the screw during transfer thereof, a timing signal transmitter for generating a timing signal every time the screw reaches the sensor, a comparator for generating an acceptance/non-acceptance signal representing the measurement results from the sensor every time the timing signal is received, a sorting signal generator for generating a sorting signal corresponding to the acceptance/non-acceptance signal when the corresponding screw reaches the end of the transfer path, and a sorter for classifying the screws into defective and nondefective screws.