Security element for security paper

Details Security element for security paper Security element for security paper

1999-09-24

2001-03-13

Lam, Cathy (Department: 1775)

Printed matter

Having revealable concealed information, fraud preventer or...

And electrically conductive material

C283S091000, C283S114000

Reexamination Certificate

active

06199911

ABSTRACT:

The invention relates to a security element for security paper for banknotes and the like having both aesthetic and anti-counterfeitable qualities.
It is widely known to use in banknotes and other security documents security elements, such as security threads or strips, which are made from a transparent film provided with a continuous reflective metal layer, such as aluminium, which is vacuum deposited on, for example, polyester film. Banknotes made from such paper have been in general circulation in many countries for many years. When the security threads are embedded in the security paper and the paper is subsequently printed to provide the security documents, the threads cannot be readily discerned in reflective light but is immediately transparent as a dark image when the document is viewed in transmitted light.
In recent times, in order to enhance the security of security documents, especially banknotes, against modern counterfeiting techniques making use of the sophisticated colour separation, printing and colour photocopier technology, it has become common to use a security thread comprising a thin layer of aluminium on a plastic support which is exposed on one side of the sheet at intervals along the length of the element, the region of exposure being referred to as a window. GB-A-1,552,853 and GB-A-1,604,463 disclose banknotes containing such windows. Paper for use in producing such banknotes can be made using the method disclosed in our European Patent Specification EP-A0,059,056. The widespread use of banknotes having security threads exposed in windows along the length of the element has resulted in enhanced security. A banknote of this type provides added security against counterfeiters as, when viewed in transmitted light, the strip is seen as a dark line, and, when viewed in reflected light on the appropriate side, the bright shiny aluminium portions which are exposed at the windows are readily visible. However, there is a need for even greater security by the use of more sophisticated devices in order to render the task of a would be counterfeiter more difficult as the reflected light appearance of the exposed aluminium portions of a security device can be simulated by modern materials and techniques, for example by the use of hot foil stamping.
More recent developments in this field include security paper with a security element as described in U.S. Pat No. 4,652,015 in which a resist and etch technique is used to selectively demetalise regions of a vacuum deposited aluminium layer on a polyester film thereby leaving security indicia comprising metal characters on the plastic strip. The strip is wholly embedded in the paper and the metal characters are undetectable to the unaided eye and in reflective illumination whilst only becoming legible in transmitted light. However, this type of thread is unsuitable for windowed applications. Because the characters are discrete and separated, the resulting look in windows is confusing and uneven.
A further improvement described in our patent specification EP-A-0,319,157 which describes the use of a partially metallised film having metal-free portions of between 10% and 50% of the area of the device, the metal-free portions along the length of the device providing a repeating pattern, design or indicia. The metal layer, however, retains a continuous metal path along its length. Banknotes formed from security threads as described therein provide excellent security and a public security feature in which the threads are eminently “readable” by the public when viewing the threads in transmitted light without the aid of a lens or other viewing accessory. In transmitted light the threads appear as black strips which very clearly stand out against their surroundings. In the embedded version, the threads are almost invisible when viewed with reflected light, although obviously the threads can be used in windowed paper also. In the windowed version, the thread is seen in reflected light as silver blocks in the windows surrounding the metal free areas.
Whilst this type of thread produces an easily recognisable effect suitable for windows or embedding, the straight edges of the negative block can be mimicked by blocking techniques.
In EP-A-0659936 a security thread is described which consists of a light transmitting plastic film with a coating which is at least partly opaque and in which the thread comprises information in the form of visually and/or machine readable characters or pattern which extend from the opaque region into an adjacent light transmitting region. This has the advantage that the visual impression can only be imitated by means of very complex techniques.
EP-A-0659587 describes a security thread which again consists of a light transmitting plastic film with a coating which is at least partly opaque. The coating has light transmitting regions in the form of visually and/or machine readable characters or patterns, which form a first type of information. A second type of information in the form of visually and/or machine readable characters or patterns is additionally disposed on the plastic film and differs from the first type of information in terms of size and/or visual impression. In the examples described in the specification there is a combination of a negative inscription, which cannot be copied because of the reflective light/transmitted light effect, with a further type of information which is particularly easy to distinguish by reflective light. Alternatively the protective effect utilises the comparison between large easily legible negative inscription and a small negative inscription which is visually difficult to resolve on a transparent plastic thread.
It is an object of the present invention to further enhance the security of security elements such as threads.
According to the invention there is therefore provided a security element for wholly or partially embedding in security paper comprising an elongate strip of a light transmitting polymeric substrate, said substrate bearing a reflective metallic layer on at least one surface thereof in the form of a design, characterised in that said design comprises at least one substantially lineal repeating pattern consisting of one or more lines or shapes formed by one or more lines, of which pattern one or more of the frequency, instantaneous amplitude and/or maximum amplitude of the pattern varies along the length of the element, the and/or at least one other geometric pattern also providing a continuous metal path along the length of the element, said design having at least one non-linear boundary.
The use of a repeating geometric pattern, as opposed to printed messages, has the advantage that it is more likely to be recognised on a narrow thread than alpha-numeric characters which become less legible as they get smaller. A repeating pattern is aesthetically more attractive than the designs delineated by straight edges which are most commonly used currently and are described in EP-A-0319157.
Alternatively a security element for wholly or partially embedding in security paper comprising an elongate strip of a light transmitting polymeric substrate, said substrate bearing a reflective metallic layer on at least one surface thereof in the form of a design, characterised in that said design comprises at least one repeating pattern consisting of one or more lines or shapes formed by one or more lines, the pattern comprising a sequence of adjacent discrete elements each incrementally different from the preceding and following elements.
Preferably at least one of the repeating patterns has a maximum width of the reflective metal layer in the transverse direction of 0.8 mm and more preferably of 0.5 mm.
In a preferred embodiment of the invention, the width of the security element is greater than or equal to 2 mm thus allowing integration of complex surface patterns into the paper substrate.
Preferably the design has at least one continuous metal path. This continuous metal path advantageously provides an electrically conductive path extending along the length of t

Affiliated with

Also associated with

Rating

Security element for security paper does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Security element for security paper, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Security element for security paper will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2498967