Dynamic information storage or retrieval – Storage medium structure – Specified material
Reexamination Certificate
1999-07-09
2001-09-18
Neyzari, Ali (Department: 2752)
Dynamic information storage or retrieval
Storage medium structure
Specified material
C430S269000
Reexamination Certificate
active
06292460
ABSTRACT:
FIELD OF THE INVENTION
The invention generally relates to the recording of information of any kind, such as analog or digital pictures, symbols, data, or the like.
The invention more particularly relates to a reusable information recording medium provided with a sensitive layer, and to a method of using such a medium for recording various elements of information.
BACKGROUND OF THE INVENTION
The need for recording information is as old as mankind, and has received solutions without number, such as painting, writing, photography, etc.
During the past 50 years, the development of computer science, the market globalization, and the consideration of environmental requirements have increased the need for re-usable information recording media, such as magnetic memories, recording tapes or discs, in which information, once recorded, is retained without consumption of energy.
More recently, the improvements of technology have increased the need for information recording media, such as re-usable optical discs, in which information can be stored with a very high density and still retained without consumption of energy.
An example of such a solution is given for instance in the published French patent application FR 2 726 116.
However, the re-usable information recording media presently known and adapted to the information recording by a computer fail to offer the possibility of being directly readable by a human being, i.e. without any specific apparatus.
OBJECT OF THE INVENTION
In this context, the purpose of the invention is to propose a re-usable information recording medium, in which information is retained without consumption of energy, and which can also display information in a visible form for the human eye.
It is also an object of this invention to propose a corresponding method for recording information and a method for erasing a recorded medium of the invention.
SUMMARY OF THE INVENTION
The re-usable information recording medium of the invention, which comprises a sensitive layer, is mainly characterized in that said sensitive layer comprises, at least, a plurality of particles having a magnetically responsive position, and a retaining material having a temperature dependent viscosity and in which said particles are embedded, said particles and said retaining material exhibiting at least respective first and second light absorption spectra which are different one from the other.
Preferably, the retaining material is chosen so that its viscosity decreases when temperature increases.
In one possible embodiment of the invention, the particles used are optically anisotropic, either by their shape and/or by their color.
The sensitive layer may further comprise a stiffening material partitioning the retaining material into a plurality of domains.
In that case, the domains, or at least most of them, may be fully surrounded by the stiffening material.
The information recording medium of the invention may also further comprise a substratum to the upper face of which is bound the sensitive layer.
A transparent protective layer may be bound to the upper face of the sensitive layer.
Depending on the applications, the retaining material may preferably be transparent or merely translucent.
In a preferred embodiment of the invention, the particles used contain a ferromagnetic material having a predetermined Curie temperature, and the retaining material is chosen so as to have a melting temperature lower than the Curie temperature of the particles.
In one embodiment of the invention, each particle can selectively adopt a position of translation among a plurality of positions of translation comprising at least a first position relatively close to an upper face of the sensitive layer, and a second position relatively remote from said upper face of the sensitive layer.
In another embodiment of the invention, each particle can selectively adopt a position of rotation among a plurality of positions of rotation comprising at least first and second different orientations of the polar axis of this particle.
As the recording medium of the invention allows information to be recorded by a control of the position of translation or of the position of rotation of the particles with regard to the upper face of the sensitive layer, the recording medium may adopt a non-recorded or initial configuration, in which all the particles have the same position, or a recorded configuration, in which at least some different particles have respective different positions.
In a preferred embodiment of the invention, the particles and the retaining material exhibit respective first and second capacities of absorbing infra-red light, the first of which is higher than the second one.
Similarly, the particles and the retaining material advantageously exhibit respective first and second capacities of absorbing visible light, the first of which is higher than the second one.
The invention also relates to a method for recording various elements of information on respective different areas of the sensitive layer of an information recording medium of the type described, in which the viscosity of the retaining material decreases when temperature increases and in which all the particles have a same position of translation and/or rotation, this method mainly comprising the step of applying to the information recording medium a magnetic field component biasing the particles towards another position of translation and/or rotation, and the step of selectively heating said different areas as a function of said various elements of information.
The step of selectively heating the different areas of the sensitive layer advantageously comprises the step of selectively directing a light beam onto said different areas.
Although the sensitive layer may be heated by a bidimensional matrix of resistors, or by a matrix of light beams, the different areas of the sensitive layer may be sequentially and selectively scanned by a light beam by relative movement between the sensitive layer and the light beam.
For a higher efficiency, the light beam preferably has an infra-red energy component.
Shades in the recorded information may be obtained by modulating the light beam in time, i.e. heating different areas of the sensible layer by light impulses of different durations, and/or by modulating the light beam in energy, i.e. heating different areas of the sensible layer by light or light impulses of different wavelengths.
The invention also relates to a method for erasing information recorded on at least some areas of the sensitive layer of the information recording medium of the type described, in which the viscosity of the retaining material decreases when temperature increases, this method mainly comprising the step of applying to the information recording medium a magnetic field component along a fixed direction, and the step of heating all the areas of the sensitive layer.
Whenever the sensitive layer should exhibit high contrast, at least some of the different areas thereof may be heated up to complete melting of the retaining material.
REFERENCES:
patent: 3673597 (1972-06-01), Horst et al.
patent: 3982334 (1976-09-01), Tate
patent: 4293634 (1981-10-01), Monosov
patent: 4438443 (1984-03-01), Doev et al.
patent: 5342682 (1994-08-01), Vogelgesang et al.
patent: 5-9227489 (1984-12-01), None
Camena Est
Neyzari Ali
Pennie & Edmonds LLP
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