Recording-media tape reel

Abstract: Disclosed herein is a recording-media tape reel including a cylindrical hub with its center line as an axis of rotation, and a pair of disc flanges extending radially from upper and lower ends of the hub. The tape reel meets the following Equation: H 1 - α > H 2 + β in which H 1 is a reference value for a distance from a reference plane perpendicular to the rotation axis along the bottom surface of the lower flange, to the radially inner end of the interior surface of the flange, α is a tolerance on the negative side of H 1 , H 2 is a reference value for a distance from the reference plane to the radially outer end of the interior surface, and β is a tolerance on the positive side of H 2 .

Description: BACKGROUND OF THE INVENTION Field Of The Invention The present invention relates to a recording-media tape reel with disc flanges at the upper and lower ends of a cylindrical hub having an outer periphery on which tape is wound. A similar type of tape reel is described in US-A-1 179 145. Description of the Related Art Magnetic tape is used as recording media that are employed in an external storage unit for computers and other recording-reproducing units. The magnetic tape is wound on a tape reel and housed within a cartridge case. If the magnetic tape cartridge is loaded into a recording-reproducing unit, rotation of the tape reel causes the magnetic tape to run, and recording or reproduction of data relative to the recording surface of the magnetic tape is performed. Recent magnetic tape has a large capacity and can store up to tens to hundreds of G bytes per reel. To realize this large capacity, a pitch between data tracks is narrowed, or tape thickness is made thin, or servo signals are written in. For this reason, the tape running mechanism of a drive unit and the cartridge structure are required to have high precision. Particularly, the precision of a reel configuration on which magnetic tape is wound is required to be high. The above-mentioned tape reel is constructed of a cylindrical hub with its center line as an axis of rotation, and a pair of disc flanges extending radially from the upper and lower ends of the hub. Space for winding recording-media tape is formed between the outer periphery of the hub and the opposing interior surfaces of the flange pair. Prior art US-A-1 179 145, mentioned above, and forming the basis for the preamble of claim 1, describes a reel for handling elongated webs such as film and recording tape. The reel comprises a hub and a pair of axially spaced flanges which extend radially from the periphery of the hub to define a web take-up chamber. Since the hub and the coiled web may rotate at different speeds, the flanges may be slightly slanted outwardly from the centre. Generally, in the case where the tape reel is made up of resin-molded components, the lower flange and the hub are integrally formed and the upper flange separately formed is fixedly attached to the upper end of the hub. The fixed attachment between the hub and the upper flange is usually performed by an ultrasonic welding method, using weld bosses or an energy director. The ultrasonic welding is being widely used for manufacturing tape reels, because it shortens manufacturing time, and because it uses a portion melted from a molded component as a binder and therefore reduces the running cost. If, in a magnetic tape cartridge with such a tape reel, the interior surface of the flange being rotated makes contact with magnetic tape, there is a possibility that the problem of damage to the magnetic tape or dust occurrence will arise. This problem becomes a more important consideration, as recording density in the magnetic tape becomes greater, and as higher reliability is needed. Particularly, if the thickness of the magnetic tape (including a magnetic recording layer) is reduced to 20 µm or less, particularly 15 µm or less, damage to the magnetic tape due to the aforementioned rubbing will become conspicuous. WO-A-0030111 describes a magnetic tape reel comprising a cylindrical hub and a pair of upper and lower flanges attached thereto and extending outward in the radial direction. One embodiment shows the interior surface of the upper and lower flanges decreasing in thickness in the direction moving away from the hub. WO-A-0079536 and WO-A-0049614 relate to European patent applications falling within Article 54(3) EPC. both these documents describe a tape reel comprising a cylindrical hub and a pair of upper and lower flanges attached thereto. The distance between the upper and lower flange at their outer edge is greater than the distance between the upper and lower flange at their inner end next to said hub. In view of the circumstances mentioned above, it is the object of the present invention to provide a recording-media tape reel that is capable of preventing recording-media tape such as magnetic tape from making contact with the interior surface of the flange. The aforementioned magnetic tape cartridge, incidentally, is divided into a one-reel type and a two-reel type. For example, a drive unit, which drives a one-reel type of tape reel, has an annular driving gear and a magnet at the top of a rotating shaft so that a chucking operation with the tape reel can be reliably performed. The drive unit is constructed such that the driving gear meshes with a reel gear formed in one end surface of the tape reel and drives the reel gear without play between them. WO-A-9965032 also describes a tape reel comprising a hub and a pair of upper and lower flanges attached thereto. This tape reel relates to a single reel using a reel gear which is meshable with a driving gear for rotating said hub. SUMMARY OF THE INVENTION To achieve the object of the present invention mentioned above, there is provided a method of constructing a recording-media tape reel comprising the steps set out in claim 1. According to the method of the present invention, the equation H 1 - α > H 2 + β is met, when H 1 is a reference value for a distance H IN from a reference plane, perpendicular to the rotation axis along an exterior surface of one of the two flanges, to a radially inner end of the interior surface of the one flange, α is a tolerance on a negative side of H 1 , H 2 is a reference value for a distance H OUT from the reference plane to a radially outer end of the interior surface of the one flange, and β is a tolerance on a positive side of H 2 . That is, the present invention is characterized in that the minimum value of H IN is always greater than the maximum value of H OUT . It is preferable that this condition be established at any position on the reel, when the thickness of the recording-media tape is 20 µ m or less, particularly 15 µ m or less, and furthermore, 10 µm or less. The reason for this is that the aforementioned damage will tend to occur more easily, as the recording-media tape is made thinner. In addition, since thinner recording-media tape is used for high-density recording, damage will become a problem even when it is slight. According to the recording-media tape reel constructed in this way, the one flange may be formed integrally with one end of the hub, and the other of the two flanges may be fixedly attached to the other end of the hub. In the case of such a tape reel, the upper and lower flanges are resin-molded components and integration of them is normally performed by ultrasonic welding, so there is a limit to the precision. Assuming ΔH = H IN - H OUT , ΔH is not always constant at all positions along the radially outer end of the flange. Because of this, the aforementioned values of H IN and H OUT have tolerances, respectively, and manufacturing precision is managed so that the values of H IN and H OUT are within the tolerances. However, since it is obvious that it is more difficult, from the mechanical standpoint, to obtain the dimensional precision of the outer distance H OUT than to obtain the dimensional precision of the inner distance H IN , a tolerance for H OUT is set wider than that for H IN . Therefore, there are cases where there occurs, depending on the size of a tolerance, a reversed phenomenon that H IN ≦ H OUT is obtained, not H IN > H OUT . According to the recording-media tape reel of the present invention, the minimum value of H IN , H 1 - α, is always greater than the maximum value of H OUT , H 2 + β. Therefore, the reversed phenomenon mentioned above will no longer occur. Even when recording-media tape is 20 µm or less in thickness, the recording-media tape can be prevented from being damaged because of rubbing between the tape and the flange interior surface. BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects and advantages will become apparent from the following detailed description when read in conjunction with the accompanying drawings wherein: FIG. 1 is a sectional view showing a tape reel constructed according to the present invention; FIG. 2 is an enlarged sectional view showing the essential part of FIG. 1; DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will hereinafter be described in detail with reference to the drawings. Fig. 1 illustrates a two-reel type tape reel to which the present invention is applied. The tape reel 1 includes a cylindrical hub 2 formed integrally with a lower flange 3, and an upper flange 4 formed as a discrete body. The cylindrical hub 2 and the upper flange 4 are welded together by ultrasonic welding. Between the outer periphery 2a of the hub 2 and the interior surfaces 3a, 4a of the upper and lower flanges 3, 4, space is formed for winding recording-media tape (not shown) such as magnetic tape, etc. Within the cylindrical hub 2, a plurality of weld bosses 5 are provided at regular intervals in the circumferential direction so that they protrude upward in parallel to an axis of rotation, R, aligned with the center line of the hub 2. On the other hand, the upper disc flange 4 has transmission holes 6 into which the weld bosses 5 are inserted, at positions corresponding to the weld bosses 5. The upper flange 4 is placed on the hub 2, and the weld bosses 5 are inserted into the transmission holes 6 so that the upper ends of the weld bosses 5 project from the upper flange 4. With the annular tip end surface of a welding horn pressed against the upper end portions of the weld bosses 5, ultrasonic waves are applied to the upper portions of the weld bosses 5 to melt the weld bosses 5. The melted weld bosses 5 are flattened so that the upper flange 4 is fixedly attached to the hub 2. The bottom surface 3b of the lower flange 3 has coaxial ribs 7, 8. A plane P, perpendicular to the rotation axis R, which includes the flat bottom faces 7a, 8a of the ribs 7, 8, is set as a reference plane along the bottom surface 3b of the lower flange 3. As illustrated in Fig. 2, the tape reel 1 is constructed such that it meets the following Equation: H 1 - α > H 2 + β where H 1 is a reference value for a distance H IN , measured parallel to the rotation axis R, from the reference plane P to the radially inner end S IN of the interior surface 3a of the lower flange 3, α is a tolerance on the negative side of H 1 , H 2 is a reference value for a distance H OUT , measured parallel to the rotation axis R, from the reference plane P to the radially outer end S OUT of the interior surface 3a of the lower flange 3, and β is a tolerance on the positive side of H 2 . That is, the interior surface 3a of the lower flange 3 is inclined by an angle of  to the reference plane P so that the radially outer end S OUT of the interior surface 3a of the lower flange 3 becomes lower than the radially inner end S IN . In addition, the minimum value of H IN is always greater that the maximum value of H OUT . Assuming that, as an example of actual dimensions, H 1 = 2.24 mm, α = ± 0.1 mm, H 2 = 2.00 mm, and β= ± 0.1 mm, H IN becomes 2.24 ± 0.1 mm and H OUT becomes 2.00 ± 0.12 mm. Since H IN ranges from 2.14 to 2.34 mm and H OUT ranges from 1.88 to 2.12 mm, the minimum value (2.14 mm) of H IN is greater that the maximum value (2.12 mm) of H OUT . Therefore, the tape reel 1 of the first embodiment meets the above-mentioned condition. Thus, according to the invention, dimensions are set so that the minimum value (H 1 - α) of H IN is always greater that the maximum value (H 2 + β) of H OUT . Therefore, the reversed phenomenon mentioned above will not occur. Even in the case where magnetic tape of thickness 20 µ m or less is employed, the invention is capable of overcoming the drawback that the magnetic tape is damaged by rubbing between the magnetic tape and the interior surfaces of the flanges 3, 4 of the tape reel 1. While the present invention has been described with reference to the preferred embodiments thereof, the invention is not to be limited to the details given herein, but may be modified within the scope of the invention claimed.

Claims: A method of constructing a recording-media tape reel comprisingthe steps of: providing a cylindrical hub (2) with its center line as an axis of rotation (R); and providing a pair of disc flanges (3,4) extending radially from upper and lower ends of said hub so that space for winding recording-media tape is formed between an outer periphery of said hub and opposing interior surfaces of said flange pair, characterized by further comprising the steps of: setting a plane (P) perpendicular to the rotation axis (R) and positioned below the bottom surface (3b) of the lower flange (3) as a reference plane; setting H 1 as a reference value for a distance H IN measured parallel to the rotation axis (R) from the reference plane (P) to the radially inner end S IN of the interior surface (3a) of the lower flange (3); setting α as a tolerance on the negative side of H 1 ; setting H 2 as reference value for a distance H OUT measured parallel to said rotation axis (R) from reference plane (P) to the raidally outer end S OUT of the interior surface (3a) of the lower flange (3); setting β as a tolerance on the positive side of H 2 ; and checking that said tape reel meets the equation H 1 - α > H 2 + β. The method according to claim 1, wherein one flange is formed integrally with one end of said hub and the other of said two flanges is fixedly attached to the other end of said hub. The method according to claim 1, wherein said recording-media tape reel is a magnetic tape reel.

Inventors: KIYOO MORITA, KIYOO, MORITA
Applicants: FUJI PHOTO FILM CO LTD, FUJI PHOTO FILM CO., LTD
Application year: 2001
Main classification: G11B23
IPC codes: G11B23