Dynamic magnetic information storage or retrieval – Record transport with head stationary during transducing – Tape record
Reexamination Certificate
2002-12-09
2004-11-16
Miller, Brian E. (Department: 2652)
Dynamic magnetic information storage or retrieval
Record transport with head stationary during transducing
Tape record
Reexamination Certificate
active
06819525
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to data cartridge library systems that are capable of storing a plurality of data cartridges, such as tape cartridges, in a storage array and selectively moving a data cartridge between the array and a drive that transfers data between a host computer and a recording medium located within a data cartridge device.
DESCRIPTION OF THE RELATED ART
Data cartridge library systems are primarily used to archive data, i.e. store data that is or may be important to the user of a computer system but not immediately needed by the user. To elaborate, the typical library system receives data from a host computer and stores the data in one or more data cartridges. When the host computer requires some of the data that was previously stored in a data cartridge, a request for the data is sent from the host computer to the library system. In response, the library system locates the data cartridge that contains the data being requested and transmits the data to the host computer.
The typical data cartridge library system is comprised of a cartridge holder with a plurality of storage slots that are used for storing a plurality of data cartridges, a player/recorder device for reading data that has been stored on the recording medium located within a data cartridge and/or writing data onto the recording medium, and a transport device for moving data cartridges between the cartridge holder and the player/recorder device. To store data in a data cartridge, the library system initially uses the transport device to load a data cartridge into the player/recorder device. Once the data cartridge has been loaded into the player/recorder device, the drive records or writes data from the host computer onto the recording medium located within the data cartridge. After all of the data has been recorded, the transport device removes the data cartridge from the player/recorder device and places the data cartridge in one of the slots of the cartridge holder. Generally, at some later time, the host computer has a need for the data stored on the data cartridge and issues a request for the data to the library system. In response, the library system identifies the slot of the cartridge holder in which the data cartridge on which the needed data is stored, causes the transport device to move the data cartridge from the slot to the player/recorder device. Once the data cartridge is loaded into the player/recorder, the desired data on the recording medium located within the cartridge is read by the player/recorder and passed on to the host computer.
SUMMARY OF THE INVENTION
The present invention addresses the need for a low-cost data cartridge library system by reducing the number of certain components, especially expensive components, that are needed to perform certain functions within the library. Cost reduction is also achieved with respect to particular library functions by using less expensive, low-precision componentry in combination with componentry that compensates for the low-precision and still provides a reduced cost relative to high-precision componentry.
One embodiment of the invention provides a data cartridge library with a picker assembly that utilizes a single electro-mechanical device to accomplish the following functions: (1) grasping a data cartridge located in either a slot of the data cartridge holder or in the drive; (2) retracting a grasped cartridge a sufficient distance from the holder or the drive so that the cartridge can be moved to another location within the library; (3) inserting a grasped cartridge into a slot of the data cartridge holder or into the drive; and (4) releasing a data cartridge that has been inserted into either a slot of the data cartridge holder or the drive. In contrast, most known data cartridge library systems use two electro-mechanical devices to accomplish the noted functions, one to perform the grasping and releasing function and the other to accomplish the retracting and inserting functions. In one embodiment, a single electro-mechanical device is used to move a cam that contacts a cam follower surface on a grasping portion of the picker, i.e. the portion of the picker that is capable of grasping, retracting, inserting and releasing a data cartridge, in a fashion that accomplishes each of the noted functions. In one embodiment, the cam follower surface includes two distinct cam follower surfaces that are contacted by different portions of the cam. Interaction between the cam with the first cam follower surface causes the grasper to be displaced either towards or away from the data cartridge holder or drive to accomplish the retraction and insertion functions, respectively. The grasping and releasing of a data cartridge is attributable to the interaction between the cam and the second cam follower surface.
A further embodiment of the invention provides a data cartridge library with a picker assembly that limits the force applied to the picker assembly during operations involving the drive. For instance, during a retraction operation, variations in the operation of one drive from another drive may result in a data cartridge being positioned closer to the picker by one drive than another drive. A data cartridge that is positioned closer to the picker than anticipated will result in the picker contacting the data cartridge sooner than expected and a force being applied by the data cartridge to the picker that could damage the picker and/or the data cartridge. Similarly, during an insertion operation, the drive may be positioned closer to the picker than anticipated and produce a similar problem. The problems can be addressed by either time consuming and perhaps expensive adjustment of the components and/or by employing high precision design techniques. The present invention reduces the need for such approaches by providing a picker with a force limiter or compensator. In one embodiment, the picker assembly employs a spring between the grasping portion of the picker assembly, i.e. the portion of the picker assembly that is used to grasp, retract, insert and release a data cartridge, and a portion of the picker that contributes to moving the grasper towards and away from the drive to compensate for the noted variations in distance of a cartridge during a retraction operation and factors that may result in an undesirable force being applied to the picker during an insertion operation. The spring permits the grasping portion of the picker assembly to move relative to the portion of the picker assembly that is used to move the grasper when a data cartridge is contacted earlier than anticipated.
Another embodiment of the invention provides a data cartridge library with a picker assembly that includes a grasper, i.e. the portion of the picker assembly that is used to grasp, retract, insert and release a data cartridge, and a device for moving the grasper during insertion and retraction operations such that the velocity of the grasper varies in a substantially sinusoidal manner. The permits the grasper to be moved at a slower velocity when near the data cartridge holder/drive and a faster velocity further from the cartridge holder/drive. In one embodiment, a circular gear with an attached cam that contacts a cam follower surface associated with the grasper is used in the retraction and insertion operations. The gear provides the sinusoidal aspect of the motion. By moving the grasper in a sinusoidal manner, greater force can be applied to a data cartridge during the point in the insertion and retraction operations involving the drive. To elaborate, some drives require that a data cartridge be forcefully inserted into and/or retracted from the drive. The greater force with the slower speed provide reliable insertion/retraction of a data cartridge into/from such drives. In another embodiment, the sinusoidal movement of the grasper is combined with the force limiter. This permits the appropriate amount of force to be applied to a data cartridge during insertion/retraction of a data cartridge with respect to the drive, while also
Brace Clark D.
Rinard Eric A.
Rinard Gregory S.
Ruff Brian A.
Holland & Hart LLP
Kulish, Esq. Christopher J.
Miller Brian E.
Spectra Logic Corporation
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