1. Field of the Invention
The present invention relates generally to a cassette type tape cartridge. Specifically, the present invention relates to a tape cartridge for magnetic tape, particularly as utilized in computer tape drive applications, for providing improved guide characteristics during tape running.
2. Description of the Related Art
External tape drives are commonly available as a computer peripheral device allowing relatively low-cost, high-volume memory storage capacity to computer users. A variety of such tape drives have been proposed including, 8 mm cassette tape drives, DAT drives, 1/4 inch tape drives etc. It is necessary in such data storage applications that tape motion be precisely controlled for prevention of errors during data storage or playback due to so-called `off track` variation wherein the tape position varies laterally while in motion. According to such tracking error, even slight variation may degrade the overall performance of the tape drive.
Referring now to FIGS. 9 and 10, a tape guide portion of a conventional tape cartridge such as disclosed in U.S. Pat. No. 5,097,374 will be discussed hereinbelow for providing background information in connection with tile related art.
As may be seen in these drawings, the conventional cartridge 101 includes a magnetic head insertion portion 102 flanked on left and right sides thereof by first and second tape guide members 104, 105 provided on an upper side of a base plate 103 of the tape cartridge.
The magnetic tape 106 of the tape cartridge is guided around each of the guide members 104, 105 from the supply and take-up reels 109, 110.
Referring now to FIG. 10, it may be seen that each of the guide member 104, 105 respectively includes an upper flange 107 and a lower flange 108. It will be noted that each flange includes a positional regulating surface portion 107a, 108a thereof on an inner side of the flange 107, 108 such that a flange width FW from the surfaces of the positional regulating portions 107a, 108a, is greater than a tape width TW of the magnetic tape 106. Referring to FIG. 10, the height H1 of upper flanges 107, 107 and the height H2 of lower flanges relative the base plate are established.
Referring to FIG. 9, the base plate 103 is also provided with cut-out portion 102 in a front edge thereof For facilitating insertion of a magnetic head (not shown) of a tape drive (not shown) for performing reading and/or writing operations with the magnetic tape 106.
Also, as seen in FIG. 9, a drive mechanism of the tape cartridge 101 is provided. At a forward side of the base plate 103, at a position corresponding to a center of the front edge a drive roller 112 is rotatably mounted. In addition, at rear corners of the base plate 103 proximate a rear edge thereof, first and second (i.e. left and right) corner rollers 113 and 114 are rotatably disposed.
A drive belt 115, made of rubber, plastic, or the like is wound around the drive roller 112 and the first and second corner rollers 113, 114 so as to pressingly contact the surface of the portions of the magnetic tape 106 wound on the reels 109, 110.
According to this construction, when a tape drive (not shown) is engaged with the drive roller 112 so as to turn the drive roller 112, the drive belt 115 is turned along its path between the drive roller 112 and the first and second corner rollers 113, 114 in a manner so as to turn the supply and take-up reels 4 and 5 so as to move the tape therebetween via the first and second tape guide portions 7 and 8, by application of frictional pressure to the outer surface of the tape 106 wound on the supply and take-up reels 109, 110. However, an amount of pressure applied to each reel 109, 110 varies according to an amount of tape wound thereon, an thus the tape guide portions 104, 105 are necessary to stabilize tape motion.
However, according to this structure, when a flange width FW is wider than a tape width TW, problems may arise as set forth below.
First of all, during tape motion, a certain amount of variation of tape position, or `meandering` in relation to the surface of the tape guide portions 104, 105 is to be expected. If the difference in FW and TW is large, then naturally, according to positional variation of the tape 106 during running, a large degree of offtracking will result.
If such meandering in the width direction occurs during signal recording on the magnetic tape 106, such signal may well prove to be unreadable during playback for retrieving the recorded data.
However, if a dimension of FW is brought close to that of TW, this will not constrain meandering of the tape. Such meandering may have various causes such as irregular motor speed, tape running while the tape drive is being moved, a tape drive capstan (not shown) of the tape drive being misaligned, or other Factors. Thus, if a certain clearance C is not provided in the flange width FW, damage to the tape edges will inevitably occur during operation and tape life and recording quality will both be degraded, and if the clearance C is provided, offtracking will inevitably result.
Thus, it has been required to provide a tape cassette in which a degree of `offtracking` may be reduced under all operational conditions.