Dynamic magnetic information storage or retrieval – General recording or reproducing – Recording-or erasing-prevention
Reexamination Certificate
1999-01-13
2001-09-18
Faber, Alan T. (Department: 2753)
Dynamic magnetic information storage or retrieval
General recording or reproducing
Recording-or erasing-prevention
C360S132000, C360S069000, C359S529000, C250S559440, C250S550000, C250S23700G, C250S559150, C250S559160
Reexamination Certificate
active
06292319
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a marker for identifying an object in a system which includes a source of irradiance and a detector of light reflected from the marker. More particularly, the present invention relates to a removable data storage cartridge and to a data storage drive for receiving the cartridge. Even more particularly, the present invention relates to detecting the presence of the correct disk cartridge in the data storage drive by use of a retroreflective marker on the cartridge.
2. Description of the Prior Art and the Problems Solved by the Invention
Disk drives for receiving removable disk cartridges, including conventional 3.5″ 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 a disk cartridge is detected. 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.
The above identified parent application entitled “Retroreflective Marker for Data Storage Cartridge” 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.
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 DEVICE PERFORMING DIVERSE FUNCTIONS”, U.S. Ser. No. 08/746,085 filed Nov. 11, 1996, Edwards, et al. now U.S. Pat. No. 5,809,320 (Attorney's Docket IOM-9319) describes such mini-cartridges, mini-drives, and hand-held devices. This application is incorporated herein by reference.
The mini-cartridge's data storage disk has a total thickness of about 2.5 mm. As disk storage products become smaller and smaller the need for a cartridge marker of thinner physical size is required. The aforementioned mini-cartridge has such a requirement. The present invention provides a solution to this requirement while maintaining the functionality of the retroreflector invention.
The ability to discriminate between cartridge types after insertion into a data storage device but prior to putting the 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.
A “caddy” cartridge, as mentioned in the aforementioned 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 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. This invention provides a solution of these problems also.
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. Since these are typically randomly located the effect on the amplitude of the reflected return is variable. A smoothing or homogenizing of reflected light in this type of system would be a significant improvement in system to system reliability.
SUMMARY OF THE INVENTION
In accordance with the present invention, an object such as a data storage cartridge has an identifying marker which includes a very thin sheet of plastic retroreflective material. The marker reflects irradiance from a source back toward the source for detection by a detector to thereby identify the object as being suitable for use in the system.
The use of a very thin retroreflective material such as Reflexite (0.006″ period) causes reflection of almost all of the light back into the source LED. In accordance with the invention a planer surface relief optical structure is placed in front of the retroreflective material. This element provides the appropriate redirection upon reflection of the light to the location of the light sensing detector.
The term “planar surface relief optical structure (PSROS) refers to thin substrates such as optically clear plastic or glass which have one or both of their surfaces modified from planar to one of texture or varying thickness. These surface relief structures can produce diffractive or refractive reshaping of the incident wavefront of light. Ruled or holographic diffraction gratings, for example are planar surface relief devices. Other names for planar surface relief structures include binary optics and holographic light shaping diffusers. Typical methods for providing this texturing or relief patterning is the use of mechanical ruling engines for the ruled gratings and photolithographic techniques for holographic diffraction gratings. Mass production of these master planar surface relief optical structures includes embossing, casting injection modeling, and thermal transfer techniques. Mass produced PSROS are typically made of plastic.
In the embodiments of this invention the PSROS is configured such that after the emitting light source wavefront is transmitted through the PSROS in one direction and reflected off the micro retroreflective structure and then again retransmitted through the PSROS the aggregate effect on the wavefront is to reshape it such that light is brought back to a predetermined location where a light detector is placed. This detector has a fixed location and orientation relative to the light emitter. This location and orientation remain a constant within the effective cone angle of the retroreflective array material no matter where the retroreflective marker is placed in a lateral plane which is a fixed distance from the retroreflective marker as long as the lateral angular orientation between the light source/detectors and the marker remains fixed. As the marker is rotated laterally relative to the emitter/detectors the reflected wavefronts orientation also rotates in unison.
Use of a light diffusing surface relief hologram provides this function. A reflected ellipse of light is sent back toward the emitter/detectors with a predetermined orientation relative to the emitter and hence a detector is placed appropriately such that this light may be detected to determine marker presence. Due to the reflection orientation or geometric location of this light the type of marker being used may be detected. Hence there is detection with a high signal to noise level and discrimination between types of markers due to geometric orientation.
Faber Alan T.
Iomega Corporation
Woodcock Washburn Kurtz Mackiewicz & Norris LLP
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