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Amp^T) / ma = A Ta = Time constant for exemplary tag A
Amp2(T) / ma = B % = Time constant for exemplary tag B
Amp3(T) / ma = C Tc = Time constant for exemplary tag C
Ampthresholdmin (t) / ma
^Pthresholdmax W / ma
LATENT ILLUMINANCE DISCRIMINATION
MARKER WITH REFLECTIVE LAYER FOR
DATA STORAGE CARTRIDGES
This application is a continuation-in-part application of U.S. application Ser. No. 09/161,007, filed on Sep. 25,1998 now pending.
FIELD OF THE INVENTION
The present invention relates in general to a system for identifying an object which includes marker, a source of irradiance, and a detector of light emitted from the marker. More particularly, the present invention relates to increasing the intensity of emitted light by disposing a reflective layer between the marker and the object.
BACKGROUND OF THE INVENTION
Disk drives for receiving removable disk cartridges, including conventional 3.5 inch floppy disk drives, must have some mechanism for detecting the insertion or presence of a disk cartridge in the drive. The actuator that carries the recording heads of the disk drive across the recording surfaces of the disk should not be allowed to move unless the presence of an appropriate disk cartridge which is non-drive damaging is detected. The removability feature requires that the disk drive have a cartridge insertion opening into which foreign objects can be inserted. If these objects physically engage the drive as a legitimate cartridge would, then the heads could be loaded onto or into the foreign object, thereby destroying the drive. Also, the spindle motor of the disk drive will be activated by a falsely detected foreign object, thereby generating particle debris. In the prior art, mechanical switches are typically employed to detect the presence of a disk cartridge within the drive. Such switches are typically positioned such that when a disk cartridge is inserted fully into the drive, the cartridge contacts the switch, thereby providing an indication that the disk cartridge is present.
"RETROREFLECTIVE 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 emitter/detector pair is in the drive and a retroreflective array is on the cartridge. The desired light lobe size is provided by the geometric size of the retroreflector array elements relative to the spacing of the emitter and the detector in the drive. Due to this physical size matching and the fact that retroreflectors are used, this marker on the cartridge is quite insensitive to cartridge tilt and distance from the emitter/detector pair in the drive. This patent is incorporated herein by reference.
Recently, very small mini-cartridges have been developed for use in miniature disc drives. These mini-drives are incorporated into hand-held devices such as digital cameras, electronic books, global positioning systems, cellular phones and the like. "INTERCHANGEABLE CARTRIDGE DATA STORAGE SYSTEM FOR DEVICES PERFORMING DIVERSE FUNCTIONS", Ser. No. 08/746, 085, filed Nov. 6, 1996, Edwards, et al, now U.S Pat. No. 5,809,520, describes such mini-cartridges, mini-drives, and hand-held devices. This application is incorporated herein by reference.
As disk storage products become smaller and smaller, the need for a cartridge marker of thinner physical size is required. In very thin disk drives where the distance between
the cartridge tag and the optical sensing device is very small (e.g., 1 mm), the inherent reflective gain mechanism obtained with a retroreflector over a diffuse or specular reflector is lost. Holographic directional light control is
5 possible, but due to the very small working distances the ability for false engagement of the drive is significantly increased with that approach.
The ability to discriminate between cartridge types after insertion into a data storage device but prior to putting the
10 read/write heads on the recording media is of significant value and utility. Principally this utility comes from the ability to detect the difference between various capacities or generations of data storage cartridges in a downward media compatible data storage drive. This discrimination capability allows for drive/media specific adjustments to be made such as media rotation rate, data channel rates, location of Z track for initial seeking, or even mechanical adjustment in the drive like the active engagement of new crash stop locations. The ability of a disk drive to predetermine the type/ generation of data storage cartridge inserted into it prior to enabling the spin-up and engagement of read/write elements also provides the drive system designer with new possibilities for cross-platform interchangeability.
A "caddy" cartridge, as mentioned in the aforementioned
25 Edwards, et al. application provides cross drive platform compatibility, for example between mini-cartridges and personal computer cartridges. The ability to recognize the installation of a "caddy" into the drive prior to spinning up of the "caddy" and loading of heads is necessary. Again
3Q rotational speed adjustments, Z track location information, data channel rate and crash stop/ID and OD data track location information must be determined prior to read/write head loading.
Another problem associated with the detection of LED
35 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
4q amplitude of the detected light signal highly variable.
Recently, in various industries, such as the distribution industry, phosphors have been used in the control of goods by means of bar codes, and furthermore, bar codes are printed on various prepaid cards and passing cards, and these
45 bar codes are read by optical reading apparatuses such as scanners to perform the desired actions. 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
50 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
55 reading apparatus. These techniques use the content or spectral shift from the irradiating light source for identification.
Although the art of detecting and discriminating between data storage cartridges is well developed, there remain some
60 problems inherent in this technology, particularly when the distance between the cartridge tag and the optical sensing device is between about 1 mm and about 15 mm. Therefore, a need exists for a tag that produces reliable detection and discrimination between data storage cartridges under vary
65 ing gain and marker spacings.
Naturally occurring materials that emit signals, such as phosphors, can be used in identification schemes where it is
important to ensure that only compatible devices are present. The emitted signal is usually quite faint and is typically amplified or increased in order for the identification scheme to perform robustly. Discrimination ratios (i.e., the ratio of the desired and the undesired signals) quantify how robustly 5 the system operates. Amplifying the signal does not increase the discrimination ratio because all signals are amplified by the same amount. Therefore, increasing the output of the emissive material is the preferred way to increase the discrimination ratio or robustness of the system. Other 10 methods of increasing light emissions include increasing the amount of material present and increasing the intensity of the light/energy source. These alternatives are not desirable because of the increased part and material cost.
It is an object of the present invention to increase the 15 efficiency of the energy transfer between the light source and the emissive material and/or increase the quantity of emissions the sensor detects without increasing the amount of material present or increasing the intensity of the light source. 20
SUMMARY OF THE INVENTION
The present invention is directed to a cartridge for a data storage drive which has a source of irradiance at an irradiance wavelength and a detector of irradiance for determining 25 whether the cartridge is suitable for use in the drive, comprising: a body; a data storage medium in the body; and a marker on the body, the marker being a latent illuminance material which receives irradiance from the source and emits irradiance having an initial intensity value toward the detec- 30 tor for detection which thereby identifies the cartridge as being suitable for use in that drive. In accordance with the invention, the intensity of the detected irradiance is increased by applying a reflective material or coating between the emissive material and the body. The reflective 35 surface has a reflectivity at charging light wavelengths and at emitting light wavelengths. The charging light, if not absorbed by the emissive material, reflects at the reflective surface and gets a 'second chance' to be absorbed by the emissive material. The light emitted from the emissive 40 material away from the sensor (detector) can be reflected by the reflective surface to the sensor. According to a further aspect of the present invention, the reflective surface could be comprised within the body itself. According to further aspects of the present invention, the reflective material could 45 be along the edges of the marker (label) substrate. According to further aspects of the present invention, the output of the emissive material, as detected by the detector, could also be increased by placing the emissive material on a concave surface focused towards the detector. 50
The foregoing and other aspects of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings. ^
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows an exemplary data storage cartridge of the present invention;
FIG. 2 is a perspective view of a device in which the m invention is used;
FIG. 3A is an exemplary latent illuminance output spectrum for a tag in accordance with the present invention;
FIG. 3B is a diagram of exemplary decay rates for exemplary tag materials in accordance with the invention; 65
FIG. 3C is an exemplary decay pattern for a tag in accordance with the present invention;
FIGS. 4A and 4B show a plan view and a cross section, respectively, of one exemplary embodiment of the invention; and
FIG. 5 shows a block diagram of an exemplary system in accordance with the present invention;
FIG. 6 shows a cross section of another exemplary embodiment of the invention with a concave reflector surface.
DESCRIPTION OF EXEMPLARY
EMBODIMENTS AND BEST MODE
The present invention is directed to a latent illuminance marker (hereinafter also referred to as a tag) which is used to identify and discriminate the type of data storage cartridge (hereinafter also referred to as a disk cartridge) that has been inserted into a disk drive. The present invention provides an optical detection mechanism so that it can be ascertained with near certainty that an inserted object is an appropriate disk cartridge. The tag system is a highly effective discriminate of appropriate cartridge insertion for a disk drive and can also be used to prevent unauthorized copies of software from being easily reproduced and used in disk drives. One means of effecting this software protection is to make the latent illuminance tag alone or in conjunction with data on the storage media a key mechanism which is inserted in the data storage drive for operation of the software. It should be noted that the term "illuminance" as used herein includes, but is not limited to, irradiance and the spectrum of light including ultra-violet (UV), visible, and near infrared.
FIGS. 1 and 2 show a cartridge and a disk drive to which the present invention is applicable. The cartridge and drive are described in the co-pending application entitled "INTERCHANGEABLE CARTRIDGE DATA STORAGE SYSTEM FOR DEVICES PERFORMING DIVERSE FUNCTIONS", Ser. No. 08/746,085, filed Nov. 6, 1996, now U.S. Pat. No. 5,809,520, which is incorporated herein by reference.
The disk cartridge 10 comprises an outer casing or body 12 and a disk-shaped recording medium 14 which is affixed to a hub 16 that is rotatably mounted in the casing 12 which is the base or substrate for the marker of the present invention. An opening on the bottom shell of the casing 12 provides access to the disk hub 16. A head access opening in the front peripheral edge 18 of the disk cartridge 10 provides access to the recording surfaces of the disk by the recording heads of a disk drive.
A latent illuminance marker, or tag, 20 is positioned on the disk cartridge 10 to be detected by a detector in a disk drive.
FIG. 2 shows a laptop computer 22 which has a disk drive 24 for receiving the disk cartridge 10 of FIG. 1. The drive 24 may be the Iomega ZIPTM drive which is disclosed and claimed in the U.S. patents identified in U.S. Pat. No. 5,638,228.
The latent illuminance marker 20 on the cartridge 10 is desirably very thin in order for the cartridge to fit in the thin form factor of the drive. Although any material exhibiting latent illuminant properties or characteristics can be used in accordance with the present invention, a phosphorescent material is used in a preferred embodiment of this invention. Materials of this type are often used for the detection of infrared radiation.
The present invention is directed to a latent illuminance tag, preferably phosphorescent, that can be attached to a data storage cartridge as a sticker, or printed into or applied via