Emi, LLC

Cyril Arthur Lee

A magnetizable anisotropic material layer having a pattern of regions of differently aligned material has an initial pattern of remanent magnetization, when manufactured by applying directional magnetic fields. This pattern is not easily restored, and is generally impossible to restore, after demagnetization or remagnetization. By preserving the residual pattern and selectively removing it in use by the application of a magnetic field, a security feature is provided. A secure document system using such a feature is provided.

Security document and system

A secure document is produced by securely attaching to a support a body of including a security feature and having a shape which conveys information to the eye. For example the body is a layer of magnetizable material having apertures of letters, numbers and the like. The document can be examined by both magnetic and optical examination apparatus to cross-check that no alteration has been made. A method of making a secure document and examination apparatus is also described. The security feature may be a pattern of magnetic anisotropy fixed into the material.

Security material and secure document system using said material

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.

Magnetic recording

Apparatus to examine a magnetic storage layer expected to contain a magnetic watermark includes means to magnetize the layer with a unidirectional field of a selected strength without saturating it and means to detect any distinct region of magnetic remanence. The apparatus may further include means to record the resultant remanence levels (or their ratio) for such a region and another part of the layer, means to magnetize the layer with a unidirectional field of a different selected strength, means to detect any then-existing such distinct region or regions, means to measure the remanence levels (or their ratio) for the then-existing such region and another part of the layer, and means to compare the measured and recorded levels (or their ratios) and indicate from the result of the comparison whether or not this represents a layer having a magnetic watermark of regions of distinctly aligned anisotropic magnetic particles. The use of different amounts of magnetization will produce different ratios of remanence in a layer having such a watermark but not in an homogenous layer.

Method and apparatus for authenticating a record medium consisting of

Magnetic record media including permanent structures of aligned acicular particles have been proposed as a means of identifying and authenticating a medium. A method of recording and reading out information on such media without interference from the permanent structure remanence variation is described. Suitable forms of magnetic record media and their manufacture are described. The use of the media and method for security documents such as credit cards is also described.

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Maidenhead, United Kingdom

Cyril Arthur Lee