Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism
Reexamination Certificate
1998-11-13
2001-10-02
Sniezek, Andrew L. (Department: 2651)
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
C360S060000, C360S133000
Reexamination Certificate
active
06297923
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an improved apparatus and method for determining whether a suitable data storage cartridge has been inserted into a disk drive, thereby protecting the drive against damage due to the insertion of disk cartridges and foreign objects that are unacceptable for use in the drive.
Removable disk cartridges for storing digital electronic information typically comprise an outer casing or shell that houses a rotatable recording medium, or disk, upon which electronic information can be stored. The cartridge shell often comprises upper and lower halves that are joined together to house the disk. The disk is mounted on a hub that rotates freely within the shell. When the cartridge is inserted into a disk drive, a spindle motor engages the disk hub in order to rotate the disk. The outer shell of the cartridge typically has some form of opening near its forward edge to provide the recording heads of the drive with access to the recording surface of the disk. A shutter or door mechanism is often provided to cover the opening when the cartridge is not in use, thereby preventing dust or other contaminants from entering the cartridge and settling on the recording surface of the disk. The term “disk cartridge,” as used in this application, refers to any data storage device, including tape cartridges.
The actuator that carries the recording heads of the disk drive across the recording surface of the disk should not be allowed to move unless the presence of a disk cartridge with an appropriate form factor, i.e., geometry, is detected. Movement of the actuator where a foreign object or a disk with an inappropriate form factor has been inserted will likely damage the drive or corrupt the data stored on the disk. Thus, when a data-storage cartridge is inserted into a drive, it is critical that the type of cartridge be recognized by the drive as a cartridge that is suitable for safe and reliable use in that particular drive. Most removable cartridge drives use cartridges having similar form factors. Additionally, foreign objects are easily inserted into disk drives. Therefore, disk drives that receive removable disk cartridges must have some mechanism for detecting the insertion or presence of a suitable cartridge within the drive. This mechanism must also be able to discriminate between cartridges appropriate for use in the drive, disks which are not suitable for the drive, and foreign objects.
In the prior art, mechanical switches are typically employed to detect the presence of a disk cartridge. Such switches are often positioned such that when a disk cartridge is fully inserted into a drive, the cartridge contacts the switch and thereby produces an indication that the cartridge is present.
Disk detection systems utilizing reflective materials have been developed and patented. For example, U.S. Pat. No. 5,638,228 (“the '228 patent”), which issued on Jun. 10, 1997, discloses such a system. The '228 patent is hereby incorporated by reference. This patent describes a disk cartridge comprising a reflective marker. The patent also describes a disk drive comprising a light emitter and a light detector coupled to an electrical circuit. When the disk cartridge is inserted into the drive, the emitter and detector become optically coupled by via the reflective marker. This coupling causes an increase in the amount of irradiance reaching the detector, which in turn causes a change in the electrical output of the detector.
As described in the '228 patent, the amount of light reflected by a reflector-equipped cartridge is greater than the amount reflected by most other objects. Therefore, by sensing that the light reflected from an object inserted into a disk drive exceeds a predetermined threshold, the detector and electrical circuit can recognize that a disk cartridge with a reflective marker has been inserted. The electronic circuit will permit activation of the drive's read/write heads under these conditions, thereby allowing the drive to interface with the disk cartridge. Conversely, when the intensity of the reflected light does not exceed the predetermined threshold, the electronic circuit interprets this as indication that a suitable data. cartridge is not present in the drive. The electrical circuit will not enable the heads under this condition, thereby preventing the drive from operating.
The emitter/detector described in the '228 patent has proven to be effective in identifying the presence of disks appropriate for use in a particular disk drive. Under certain limited circumstances, however, the '228 design allows activation of the drive in the presence of disks and foreign objects that may damage the drive. Such activation occurs because objects having surface reflectivities similar to or greater than that of a reflector are interpreted by the '228 design as disks appropriate for use in the drive. Hence, there is a need to provide a greater degree of differentiation between disks appropriate for use in a particular drive, and disks and other objects that can damage the drive if inserted.
SUMMARY OF THE INVENTION
The present invention comprises a disk-detection system that provides improved discrimination between objects suitable and unsuitable for use in a particular disk drive. The invention comprises a light emitter and a light detector. These components are used in conjunction with a data-storage cartridge equipped with a reflective marker. The emitter is oriented such that the light generated by the emitter strikes the surface of the marker an angle substantially less than 90 degrees. The detector is located directly adjacent to the emitter, and is oriented in a manner similar to that of the emitter.
The noted improvement in object differentiation stems from the fact that certain surfaces possess the relatively unique ability to reflect light back along its incident path when the incident angle is substantially less than 90 degrees (“incident path” refers to the path of the incident light at it travels toward the reflecting surface; “incident angle” is the angle at which incident light strikes the reflecting surface). Hence, when a cartridge comprising such a surface is inserted into a disk drive that incorporates an emitter and detector oriented in the above-noted manner, the detector will be illuminated by light reflected from that surface. Conversely, when most other objects are inserted into such a drive, most or all of the light incident upon the object will be reflected in directions other than the incident direction. Hence, the detector will not register a change in output voltage under such conditions, and the electrical circuitry in the drive will not allow activation of the drive.
In a preferred embodiment of the invention, a data-storage cartridge is equipped with a retro-reflective marker comprising a plurality of reflective panels. Each reflective panel is angled in relation to the top and bottom surfaces of the marker, i.e., the surfaces of the marker that lie flush with the surrounding cartridge structure. In the preferred embodiment, a portion of the emitter is angled such that the emitted light strikes some of the reflective panels at an angle of about 90 degrees. More specifically, the angle between the light-emitting surface of the emitter and the bottom surface of the cartridge is matched with the angle between the reflective panels and the top surface of the marker. This geometry disposes the light-emitting surface and a plurality of the reflective panels in substantially parallel planes.
The noted geometrical configuration results in an optimal reflection along the light's incident path, i.e., back toward the detector. Hence, when a cartridge equipped with a retro-reflective marker is installed in the exemplary drive, the detector will be illuminated by a relatively strong reflection from the marker. Conversely, when an object that is not equipped with a retro-reflective marker is placed in the drive, any reflection along the incident path will, in general, be low or non-e
Burnside Michael C.
Lee Dale E.
Iomega Corporation
Sniezek Andrew L.
Woodcock Washburn Kurtz Mackiewicz & Norris LLP
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