Magnetic recording media including permanent structures of aligned acicular particles have been proposed as a means of identifying and authenticating a medium. A structure of such a media by which information can be recorded and read-out without interference from the structural remanence difference is described. An apparatus and method for the examination of such media for their permanent structures, particularly when used in security documents such as credit cards, are also described.
Data validation uses redundant storage of the data on two-layer magnetic tapes. A method and system provide data recording and reading on such magnetic tapes with a high degree of protection from errors and/or fraudulent behavior. The two-layer tape includes a first layer with a high coercive field positioned on a support and a second magnetic layer with a lower coercive field covering the first layer. Synchronous recording is done on the two layers so that all data is recorded on the second layer and some of the date is recorded on the first layer. Data on the second layer is validated upon reading by reading the data in the first layer after erasure of the second layer.
With an automatic wicket apparatus, a commutation ticket is provided With a second record section for recording a character pattern corresponding to information for entrance or exit in the form of a magnetic latent image, besides a first record section for encoding and recording the information for entrance or exit. At the time of entrance, a character pattern including the date of entrance and entraining station name is recorded as a magnetic latent image in the second record section. At the time of exit, a character pattern including the date of exit and alighting station name is recorded as a magnetic latent image in the second record section. In case of suspicion, the character pattern in the form of a magnetic latent image in the second record section of the record medium is visualized by using a magnetic latent image-visible image conversion member.
Methods and apparatus for increasing the density of data storage on a magnetic medium by using variations in positioning of magnetic transitions to encode bits. Conventionally encoded bits are written to the medium as sequences of magnetic transitions according to an encoding standard. Additional bits are encoded on the medium as deviations from a nominal position of magnetic transitions separating conventionally encoded bits. The deviation from the nominal position is within an allowable range of tolerance for the standard followed in encoding the conventionally encoded bits. In order to prevent accumulation of error, additional bits are only encoded in transitions separating a pair of conventionally encoded bits. The first and last transitions of the pair do not have additional bits encoded as deviations of transition locations. This technique allows the encoding of one additional bit for every two conventionally encoded bits.
A secure card such as a credit card having a magnetic strip thereon is disclosed. The magnetic strip is coated with a thin amorphous layer having electrical characteristics and a processor. In a first state, the amorphous layer acts to interfere with reading of information from the magnetic strip. Identification of a user of the card as an authorized user thereof results in a second state in which the information stored in the magnetic strip is accessible. For example, biometric identification or the use of a PIN entered either directly into the card or through an input terminal cause the processor to switch power from the amorphous strip thereby removing the interference and unmasking the information on the magnetic strip.
Methods and apparatus for increasing the density of data storage on a magnetic medium by using variations in positioning of magnetic transitions to encode bits. Conventionally encoded bits are written to the medium as sequences of magnetic transitions according to an encoding standard. Additional bits are encoded on the medium as deviations from a nominal position of magnetic transitions separating conventionally encoded bits. The deviation from the nominal position is within an allowable range of tolerance for the standard followed in encoding the conventionally encoded bits. In order to prevent accumulation of error, additional bits are only encoded in transitions separating a pair of conventionally encoded bits. The first and last transitions of the pair do not have additional bits encoded as deviations of transition locations. This technique allows the encoding of one additional bit for every two conventionally encoded bits.
