Method and an apparatus for checking objects to be checked for authenticity

An apparatus for checking the authenticity of a checking object which includes a base formed of a non-magnetic material, a scanning region provided in the base, a code indicator section provided in the base, and a number of high-permeability magnetic elements dispersed in the scanning region, the apparatus comprising:

• exciting means for applying a DC bias magnetic field to said high-permeability magnetic elements dispersed in said scanning region;
• said bias magnetic field having a magnitude such that said high-permeability magnetic elements are restored from a magnetized state back to an original state when application of the bias magnetic field is stopped,
• a transportation mechanism for moving the scanning region relatively to the magnetic field at a predetermined speed;
• detecting means for picking up a change in standing of a magnetic flux, which varies depending on the distribution of said high-permeability magnetic elements, thereby detecting a detection signal for the change of the magnetic flux, as the scanning region passes through the bias magnetic field;
• code writing means for recording a code corresponding to the detection signal in the code indicator section of the checking object;
• reading means for reading the code recorded in the code indicator section;
• and
• means for collating the code read by the reading means with the detection signal detected by the detecting means and concluding that the checking object is real when the read code and the detection signal correspond to each other.

A method for checking the authenticity of a checking object which includes a base formed of a non-magnetic material and a number of high-permeability magnetic elements dispersed in a scanning region of the base, comprising the steps of:

• a manufacturing process for manufacturing the checking object;
• and
• a collating process for checking the checking object,
• the manufacturing process including the following steps:
• an excitation step of applying a magnetic field to said high-permeability magnetic elements dispersed within the scanning region by means of a magnetic field generator while simultaneously passing the scanning region between the magnetic field generator and a magnetic sensor,
• said magnetic field having a magnitude such that said high-permeability magnetic elements are restored from a magnetized state back to an original state when application of the magnetic field is stopped,
• a step of detecting a detection signal for a change in standing of a magnetic shielding effect, which varies depending on the distribution of the high-permeability magnetic elements, by means of the magnetic sensor, as the scanning region crosses the magnetic field, said excitation step and said step of detecting being executed simultaneously,
• a step of obtaining a cipher code by enciphering the detection signal, and
• a step of recording the cipher code in a code indicator section of the checking object, and
• the collating process including the following steps:
• an excitation step of applying the magnetic field to said high-permeability magnetic elements within the scanning region by means of the magnetic field generator while simultaneously passing the scanning region between the magnetic field generator and the magnetic sensor,
• a step of detecting the detection signal for the change in standing of a magnetic shielding effect, which varies depending on the distribution of said high-permeability magnetic elements, by means of the magnetic sensor, as the scanning region crosses the magnetic field, said excitation step and said step of detecting being executed simultaneously,
• a step of reading the cipher code recorded in the code indicator section,
• a step of reproducing a code for collation by decoding the cipher code, and
• a step of collating the collation code reproduced in the code reproduction step with the detection signal detected in the detection step and concluding that the checking object is real when the collation code and the detection signal correspond to each other.

An apparatus for checking the authenticity of a checking object which includes a base formed of a non-magnetic material, a scanning region provided in the base, a code indicator section provided in the base, and a number of high-permeability magnetic elements dispersed in the scanning region, the apparatus comprising:

• a first exciting coil for applying a first alternating field to said high-permeability magnetic elements dispersed in said scanning region, said first alternating field having a magnitude such that said high-permeability magnetic elements are restored from a magnetized state back to an original state when application of said first state alternating magnetic field is stopped,
• a first magnetic sensor opposed to the first exciting coil;
• a transportation mechanism for passing the scanning region between the first exciting coil and the first magnetic sensor;
• a second exciting coil situated in a position magnetically isolated from the first exciting coil and used to generate a second alternating field identical with the first alternating field;
• a second magnetic sensor opposed to the second exciting coil;
• a circuit for fetching a detection signal corresponding to the difference between an output produced in the first magnetic sensor and an output produced in the second magnetic sensor as the scanning region passes between the first exciting coil and the first magnetic sensor;
• code writing means for recording a code corresponding to the detection signal in the code indicator section of the checking object;
• reading means for reading the code recorded in the code indicator section;
• and
• means for collating the code read by the reading means with the detection signal and concluding that the checking object is real when the read code and the detection signal correspond to each other.