PURPOSE: To obtain a magnetic card having high security by providing a wavelength-absorbing material which absorbs a predetermined wavelength, at least, on part of the surface.
CONSTITUTION: A magnetic card consists of a wavelength absorbing material which absorbs a predetermined wavelength provided on at least, part of the surface. A wavelength absorber absorbs an infrared ray, and is composed of at least, one type of rare earth element with a powdery appearance and an average grain diameter of 0.01 to 10μm. The absorptive amount of infrared ray is measured by irradiating the magnetic card with an infrared ray of specified wavelength, and the identify of the magnetic card is checked based on the measured absorptive amount. The rare earth elements which absorb a light of 900nm or higher are ytterbium Yb, dysprosium Dy and samarium Sm. These elements are generally very difficult to obtain. If these elements are applied to the card and the falseness of the card is determined using a sensor, the card will be a effective device for forgery prevention.
SUZUKI TETSUO
TAKAHASHI HIDEO
| JPS6480594A | 1989-03-27 | |||
| JPS6420663A | 1989-01-24 |