Registers – Coded record sensors – Particular sensor structure
Reexamination Certificate
1998-09-25
2001-07-24
Le, Thien M. (Department: 2876)
Registers
Coded record sensors
Particular sensor structure
C235S462020
Reexamination Certificate
active
06264107
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates in general to a marker for identifying and/or authenticating an object or article in a system which includes a source of irradiance and a detector of light emitted from the marker. More particularly, the present invention relates to an object having a marker and to a reader for receiving the object. Even more particularly, the present invention relates to detecting the presence of a correct or authentic object in the reader by use of a latent illuminance marker on the object.
BACKGROUND OF THE INVENTION
A whole range of different solutions to the problem of authenticating and validating an article or object, such as a document or data storage cartridge, have been proposed, such as marking with radioactive isotopes, marking with non-radioactive tracer substances which under neutron irradiation partially absorb the radiation, and marking with UV-fluorescing substances. All these proposed solutions are accompanied by considerable drawbacks.
The first two mentioned proposals have the advantage that substances are being used which are difficult to obtain with the view of forging or counterfeiting, but which at the same time suffer from the major drawback that radioactive radiation is being used, this being subject to stringent regulation and apt to cause apprehension in some people who might come in contact therewith. UV-fluorescence requires a high voltage and is difficult to modulate.
Bar codes have also been used to identify articles. In general, a bar code is printed on a substrate such as a prepaid card with black ink. From the mark, information is read by irradiating the mark and detecting variation of reflected light by using a difference of reflectance between a printed part and a non-printed part. Thus, these bar codes are read by optical reading apparatuses such as scanners to perform the desired actions.
One problem associated with the detection of light reflected from any reflective material is the occurrence of illuminance hot spots or structure in the light output which often results in uneven illumination of the cartridge marker. Reflective markers can also become faded, scratched, or soiled. These factors combine to make the amplitude of the detected light signal highly variable.
Recently, in various industries such as the distribution industry, latent illuminance materials such as phosphors have been used in bar codes for the control of goods. Moreover, various attempts have been made to apply forgery preventive means to credit cards and prepaid cards or to detect forged cards. For example, the marks such as bar codes are printed with an ink containing a phosphor by offset printing or by using an ink ribbon to form latent image marks. The latent image marks are irradiated with a semiconductor laser beam to excite the phosphor and the light emitted from the phosphor is received to read the bar code information by an optical reading apparatus. These techniques use the spectral content of the latent illuminance for identification. It is known that read errors occur frequently with spectral content identification techniques.
Prior cartridge type products have used a retro-reflective marker to identify the disk type. “RETRO-REFLECTIVE MARKER FOR DATA STORAGE CARTRIDGE”, U.S. Pat. No. 5,638,228, to Thomas, III, describes the reflection of a highly concentrated quasi circular lobe of light whose spread on reflection is captured by the aperture of a phototransistor in close proximity to a light emitting diode (LED). This excitor/detector pair is in the drive and a retro-reflective array is on the cartridge. The desired light lobe size is provided by the geometric size of the retro-reflector array elements relative to the spacing of the excitor and the detector in the drive. Due to this physical size matching and the fact that retro-reflectors are used, this marker on the cartridge is quite insensitive to cartridge tilt and distance from the excitor/detector pair in the drive. Another problem associated with the detection of LED light reflected from any reflective material is the occurrence of illuminance hot spots or structure in the LED output which often results in uneven illumination of the cartridge marker. Reflective cartridge markers can also become faded, scratched, or soiled. These factors combine to make the amplitude of the detected light signal highly variable. This patent is incorporated herein by reference.
“LATENT ILLUMINANCE DISCRIMINATION MARKER FOR DATA STORAGE CARTRIDGES”, filed concurrently with this application, Thomas III, et al. (Attorney's Docket IOM-9689), describes a system for identifying and discriminating removable data storage cartridges and a data storage drive for receiving the cartridge. This system relates to the detection of the correct disk cartridge in the data storage drive by use of the decay time of a latent illuminance tag, preferably a phosphor tag disposed on the cartridge.
“LATENT IRRADIANCE DISCRIMINATION METHOD AND MARKER SYSTEM FOR CARTRIDGELESS DATA STORAGE DISKS”, filed concurrently with this application, Krieger, et al. (Attorney's Docket IOM-1150), describes a system for identifying and discriminating removable cartridgeless data storage disks and a data storage drive for receiving the disk. This system relates to the detection of the correct disk in the data storage drive by use of the decay time of a latent illuminance tag, preferably a phosphor tag disposed on the disk.
Although the art of identifying and authenticating objects and articles using markers and bar codes is well developed, there remain some problems inherent in this technology, particularly in increasing the difficulty of counterfeiting and decreasing the probability of read and detection errors. Therefore, a need exists for a marker that produces reliable detection and discrimination.
SUMMARY OF THE INVENTION
The present invention is directed to a checkable object, characterized in that it is provided with a marker comprising a rare earth phosphorescent material, with the property that it emits irradiance having a latent wavelength illuminance spectrum in the range between about 450 nm and about 1050 nm and has a latent illuminance decay time which is used to identify the object when irradiated with a source of irradiance. Preferably, the source of irradiance has an irradiance wavelength outside of the latent illuminance wavelength spectrum, and the decay time is in the range between about 50 &mgr;sec and about 1 sec.
According to one aspect of the present invention, the decay time is an amount of time for the irradiance from the marker to decay to a predetermined intensity value or an amount of time it takes for the irradiance from the marker to decay from a first predetermined intensity value to a second predetermined intensity value. Preferably, the irradiance from the marker has an intensity that decays exponentially or as the sum of differently weighted exponential decays. More preferably, the intensity of the irradiance decays according to e
−(t/(T/X))
, where T is a decay time constant for a predetermined amount of decay, X is a predetermined constant, and t is a time that has elapsed from when the source of irradiance stops providing the irradiance.
According to further aspects of the present invention, the rare earth phosphorescent material is coated on a pressure sensitive sticker substrate, suspended in an adhesive or a glue, blended with an ink and printed on the object, or injection molded on the object.
According to one aspect, the marker further comprises a filter to absorb light having a predetermined range of wavelengths. Preferably, the filter comprises a rare earth element.
In a further embodiment within the scope of the present invention, a method of marking and checking an object is provided, comprising the steps of: at the time of marking, providing the object with a phosphorescent material, with the property that it emits irradiance having a latent illuminance wavelength spectrum in the range between about 450 nm and about 1050 nm and has a latent illuminance decay
Dixon Glenn B.
Thomas, III Fred C.
Iomega Corporation
Le Thien M.
Woodcock Washburn Kurtz Mackiewicz & Norris LLP
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