There is provided a reel, the reel in which a difference in winding radii across the entire recording tape width between a winding terminal end of a first turn and a winding start end of a second turn of a recording tape that has been wound around a hub is 1.3 times a thickness of the recording tape, or less.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC 119 from Japanese Patent application No. 2015-066199 filed on Mar. 27, 2015, the disclosure of which is incorporated by reference herein.

BACKGROUND

1. Technical Field

The present disclosure relates to a reel.

2. Related Art

Conventional tape cartridges are known in which a single reel, with a recording tape such as magnetic tape wound around an outer peripheral face of a hub, is housed inside a case. Conventional reels of such conventional tape cartridges are also known in which a center line average roughness Ra of the outer peripheral face of the hub is stipulated to be from 0.005 μm to 0.04 μm (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 2003-30952).

Conventional winding methods are also known in which a free end portion of the recording tape is caused to make sliding-contact with the outer peripheral face of the hub, and the free end portion of the recording tape adheres to the outer peripheral face of the hub due to abraded powder that is generated as a result (see, for example, JP-A No. 2010-215327).

However, in reels that are molded by a mold in which a gate forming an injection inlet for melted resin material is, for example, disposed in a position that forms a center portion of a bottom plate of the hub, three hole portions are sometimes formed at equal intervals around the circumferential direction to the bottom plate further to the radial direction inside than an inner peripheral face of the hub. In such cases, the melted resin material that has been injected through the gate is divided by the portions forming the hole portions, flows toward the radial direction outside, and converges at a portion forming the hub.

Weld lines along the axial direction are therefore liable to form at the outer peripheral face of the hub positioned at the radial direction outside of the hole portions (seeFIG. 7). A phenomenon is also seen in which portions of the mold facing the weld lines degrade over time. The cause of this phenomenon is thought to be as described below. Namely, when molding using the mold, corrosive gas generated by the melted resin flows in a manner similar to that of the melted resin, and so is liable to concentrate at portions formed by the weld lines (hereafter referred to as “weld portions”), and portions of the mold facing the weld lines sometimes corrode over time due to this corrosive gas.

When part of the mold corrodes, the corroded portion is transferred to the outer peripheral face of the reel hub, such that the weld portions have a rougher surface than portions where the weld lines are not formed (hereafter referred to as “non-weld portions”). Thus, when the free end portion of the recording tape is caused to make sliding-contact with the outer peripheral face of the hub, in order to be adhered thereto, more abraded powder than required is generated at the weld portions.

In particular, recording tapes have become even thinner in recent years, such that, when the recording tape with the free end portion adhered to the outer peripheral face of the hub is wound around for a first turn, a second turn, a third turn, and so on, a step (creasing) that cannot be ignored of the thickness of the recording tape or greater occurs in the recording tape from the second turn onward superimposed on the free end portion, due to abraded powder interposed between the free end portion and the outer peripheral face of the hub.

When a step occurs in the recording tape that has been wound around the hub, when the recording tape is run while rotating the reel for a predetermined number of rotations, and the recording tape is recorded on or played back by a recording and playback head of a drive device, the behavior of the recording tape at the portion where the step has occurred changes suddenly, such that a recording defect or a playback defect (hereafter referred to as “drop-out”) may occur in the recording and playback head.

SUMMARY

The present disclosure obtains a reel capable of suppressing drop-out from occurring when recording on or playing back a recording tape using a recording and playback head.

A first aspect of the present disclosure is a reel, wherein a difference in winding radii across the entire recording tape width between a winding terminal end of a first turn and a winding start end of a second turn of a recording tape that has been wound around a hub is 1.3 times a thickness of the recording tape, or less.

A second aspect of the present disclosure is a reel, wherein: an end portion of a recording tape is adhered to a hub by interposing abraded powder; and a difference in winding radii across the entire recording tape width between a winding terminal end of a first turn, and a winding start end of a second turn of the recording tape that has been wound around the hub is 1.3 times the thickness of the recording tape, or less.

The present disclosure enables drop-out to be suppressed from occurring when recording on or playing back a recording tape using a recording and playback head.

DETAILED DESCRIPTION

Detailed explanation follows regarding exemplary embodiments of the present disclosure, based on the drawings. First, simple explanation follows regarding a recording tape cartridge10that houses a single reel20, and then explanation follows regarding the reel20. Note that when a recording tape T is wound onto the reel20according to the present exemplary embodiments, the winding is performed by a winding method described in JP-A No. 2010-215327.

As illustrated inFIG. 1, the recording tape cartridge10includes a case12made of a resin such as polycarbonate (PC). The case12is formed in a substantially rectangular box shape, and the single reel20made of a resin such as polycarbonate (PC) is housed alone so as to be capable of rotating at the inside thereof.

An opening14for pulling out the recording tape T that has been wound onto the reel20is formed in a side wall of the case12. A leader pin16, which is anchored and pull-operated by a pulling member (not illustrated in the drawings) of a drive device (not illustrated in the drawings), is fixed to a free end portion Te of the recording tape T that is pulled out from the opening14.

The opening14is opened and closed by a door18. The door18is formed in a substantially rectangular plate shape of a size capable of closing the opening14, and is biased in a direction that closes the opening14by a biasing member (not illustrated in the drawings). The door18is opened against the biasing force of the biasing member as the recording tape cartridge10is mounted onto the drive device.

First Exemplary Embodiment

Explanation follows regarding the reel20according to a first exemplary embodiment. As illustrated inFIG. 2AandFIG. 3, the reel20is configured by a circular tube shaped reel hub22that configures an axial center portion, a lower flange24serving as a flange that is integrally provided at a lower end portion of the reel hub22, an upper flange26serving as a flange that is provided at and joined to an upper end portion of the reel hub22, and a bottom plate28that is integrally provided so as to close the lower end portion of the reel hub22.

Note that a reel component member30of the present exemplary embodiment is configured by the reel hub22, the lower flange24, and the bottom plate28. The recording tape T, which is a magnetic tape or the like serving as an information recording and playback medium, is wound around an outer peripheral face22A of the reel hub22, and width direction end portions of the wound recording tape T are protected by the lower flange24and the upper flange26(seeFIG. 2B).

As illustrated inFIG. 3andFIG. 4A, three engagement gears32are formed at equal intervals around the circumferential direction to an upper face of the bottom plate28further to the radial direction inside than an inner peripheral face of the reel hub22. When the recording tape cartridge10is not mounted to the drive device and is not in use, the engagement gears32mesh with brake gears of a brake member (not illustrated in the drawings) that is incapable of rotating with respect to the case12.

As illustrated inFIG. 3andFIG. 4B, a reel gear34is formed in a ring shape to a lower face of the bottom plate28further to the radial direction inside than the inner peripheral face of the reel hub22. A ring shaped reel plate36formed of a magnetic material is integrally fixed by insert molding or the like to the lower face of the bottom plate28, further to the radial direction inside than the reel gear34.

Three hole portions38, inserted with leg portions of a release member (not illustrated in the drawings) provided inside the reel hub22in order to release the braking of the reel20by the brake member, are formed at equal intervals on top of the reel gear34. A gate mark46is formed further to the radial direction inside than the reel plate36, at a center portion of the bottom plate28(the axial center of the reel20) in this embodiment.

A gear opening (not illustrated in the drawings) to expose the reel gear34and the reel plate36to the outside is formed in substantially a center portion of a lower wall of the case12. The reel gear34that is exposed through the gear opening is enmeshed with a drive gear (not illustrated in the drawings) formed to a rotary shaft (not illustrated in the drawings) of the drive device.

The enmeshing operation with the rotary shaft presses the leg portions of the release member toward the axial direction upper side, the release member presses the brake member upward toward the axial direction upper side, and releases the enmeshing of the brake gears with the engagement gears32, such that braking on the reel20is released. The reel20which has been released from braking rotates inside the case12due to the rotary shaft being rotation-driven.

Winding Method

Explanation follows regarding a winding method in which the recording tape T is adhered to and wound around the outer peripheral face22A of the reel hub22in the reel20configured as described above, without being coated with a liquid for adhering. Note thatFIG. 5AandFIG. 5Bare plan view cross-sections illustrating only the reel hub22of the reel20, in order to simplify the explanation (the drawings). A resilient body48, described later, is configured by a sponge form material that has an appropriate hardness (such as hardness of22using a measuring method based on the Society of Rubber Industry, Japan Standard (SRIS) 0101).

As illustrated inFIG. 5A, the reel20is set on a rotary drive gear (not illustrated in the drawings) of a winding device. Namely, the reel gear34of the reel20is enmeshed with the rotary drive gear. Note that the reel plate36is attracted to a magnet (not illustrated in the drawings) provided at the radial direction inside of the rotary drive gear when this is performed.

A free end portion Tf, forming the opposite side of the recording tape T to the free end portion Te that is attached to the leader pin16, is retained by air suction to an upper face50A of a retaining mechanism50of the winding device. The resilient body48provided in a recessed portion52of the retaining mechanism50then presses the outer peripheral face22A of the reel hub22, with the free end portion Tf interposed therebetween.

Namely, the free end portion Tf of the recording tape T that is present on top of the resilient body48is caused to contact the outer peripheral face22A of the reel hub22with a predetermined pressure. The reel hub22is then rotated for several seconds at a predetermined speed (such as 300 rpm) in the arrow A direction illustrated inFIG. 5A, and the outer peripheral face22A of the reel hub22is caused to make sliding-contact with the recording tape T for a predetermined distance or more (such as 2000 mm or more). As illustrated inFIG. 5B, the free end portion Tf of the recording tape T adheres to the outer peripheral face22A of the reel hub22when this is performed.

Note that the adhesion force of the recording tape T is determined by a surface roughness Ra (nm) of a non-magnetic face, this being the contact face of the recording tape T (hereafter referred to as “back face Tb”) contacting the outer peripheral face22A of the reel hub22, and the contact duration. Namely, in cases in which the surface roughness Ra of the back face Tb of the recording tape T is low (a smooth face with Ra<approximately 5 nm), there is a large friction force against the outer peripheral face22A of the reel hub22, such that there is a large adhesion force (adhesion is easy). In such cases, the recording tape T thereby adheres to the reel hub22(outer peripheral face22A), even if the contact duration (contact distance) thereto is short.

However, in cases in which the surface roughness Ra of the back face Tb of the recording tape T is high (a rough face with Ra≧approximately 5 nm), there is a small friction force against the outer peripheral face22A of the reel hub22, such that there is a low adhesion force (adhesion is difficult). In such cases, the contact duration (contact distance) of the reel hub22(outer peripheral face22A) against the recording tape T is thereby lengthened to increase the adhesion force. When the contact duration (contact distance) is lengthened, abraded powder D is generated at the back face Tb of the free end portion Tf (seeFIG. 8,FIG. 9), and it is thought that the adhesion force against the reel hub22(outer peripheral face22A) is increased by this abraded powder D.

Simple explanation regarding this mechanism follows below. An oxide film is formed to the outer peripheral face22A of the reel hub22. Thus, when the back face Tb of the recording tape T and the outer peripheral face22A of the reel hub22(the oxide film) rub against each other in a pressed-together state, part of the oxide film is stripped away, and fine protrusions on the back face Tb are ground down. The abraded powder D is generated, and the abraded powder D adheres to the outer peripheral face22A of the reel hub22.

The abraded powder D is spread out due to the sliding-contact of the reel hub22against the recording tape T, such that the bonding force is increased (in particular, surface energy rises at the outer peripheral face22A where the oxide film has been stripped off, and the bonding force thereof is increased). The abraded powder D with increased bonding force accordingly performs the role of an adhesive, thereby obtaining adhesion force of the recording tape T (free end portion Tf) against the outer peripheral face22A of the reel hub22.

Moreover, due to fine protrusions on the back face Tb of the recording tape T being ground down, the back face Tb is closer to being a smooth face, such that the friction force against the outer peripheral face22A of the reel hub22is also increased. Thus, even in a recording tape T that has high surface roughness Ra (a rough face) of the back face Tb, adhesion force of the free end portion Tf against the outer peripheral face22A of the reel hub22is increased, and the free end portion Tf adheres to the outer peripheral face22A of the reel hub22.

The free end portion Tf of the recording tape T is adhered to the outer peripheral face22A of the reel hub22by the above mechanism, without using any liquid for adhering recording tapes, such as alcohol. Note that, when the free end portion Tf of the recording tape T has adhered to the outer peripheral face22A of the reel hub22, the air suction by the retaining mechanism50is released, and as illustrated inFIG. 5B, the retaining mechanism50is separated from the reel hub22.

The rotary drive gear of the rotation mechanism is then rotated at a lower speed (such as 60 rpm) than the rotation speed during the above-described sliding-contact, while a predetermined tensile force (such as approximately 0.01N in cases in which the thickness of the recording tape T is 5.2 μm) is applied to the recording tape T. When a predetermined amount of the recording tape T has been wound around the reel hub22, the rotary drive gear is then rotated at a high speed, and the recording tape T is sequentially wound onto the reel hub22.

As illustrated inFIG. 2B, the reel20is thereby ultimately in a state with the recording tape T wound thereon. Note that, as illustrated inFIG. 8, when this winding method is employed, adhesion may be performed in a state in which predetermined gaps S1, S2are respectively formed between edges of the recording tape T, and the lower flange24and the upper flange26(the recording tape T does not slope toward the lower flange24side or the upper flange26side).

Next, explanation follows regarding a mold60that integrally molds the reel hub22, the lower flange24, and the bottom plate28of the reel20, namely, regarding configuration and operation of the mold60that molds the reel component member30.

As illustrated inFIG. 6, the mold60includes a fixed side mold60A and a movable side mold60B, and a space for molding the reel component member30(respective formation portions, described later) by abutting the movable side mold60B against the fixed side mold60A. Explanation follows regarding the respective formation portions that form the reel component member30.

The mold60is manufactured by steel or the like, and includes a hub formation portion62for forming the reel hub22, a flange formation portion64for forming the lower flange24, and a bottom plate formation portion68for forming the bottom plate28. An anticorrosion coating CT is applied to a wall face62A of the hub formation portion62that forms the outer peripheral face22A of the reel hub22.

A gate66for injecting melted resin material such as PC into the mold60is disposed further to the radial direction inside than a wall face62B of the hub formation portion62that forms the inner peripheral face of the reel hub22, and is disposed at a center portion of the bottom plate formation portion68(the axial center of the reel20) in this example. Thus, when melted resin material is injected through the gate66, the resin material flows from the bottom plate formation portion68toward the hub formation portion62and the flange formation portion64.

Note that the three hole portions38are formed in the bottom plate28at equal intervals around the circumferential direction. Three column portions58are therefore provided to the bottom plate formation portion68at equal intervals around the circumferential direction. The resin material flowing from the bottom plate formation portion68toward the hub formation portion62side is temporarily divided by the respective column portions58, and then converges inside the hub formation portion62. As illustrated inFIG. 7, a weld line42that runs substantially along the axial direction is accordingly formed to the outer peripheral face22A of the reel hub22at the radial direction outside of each hole portion38formed by the respective column portion58.

During molding using the mold60, corrosive gas is generated from the melted resin material. The corrosive gas flows in a similar manner to that of the melted resin material, and so is liable to concentrate at convergence portions of the resin material inside the hub formation portion62. Thus, in cases in which the anticorrosion coating CT is not applied to the wall face62A of the hub formation portion62, it is conceivable that parts of the wall face62A (locations facing the weld lines42) corrode over time due to the corrosive gas, and that the roughness of these parts of the wall face62A is transferred to the outer peripheral face22A of the reel hub22. Weld portions40including the weld lines42are thereby formed at equal intervals in three locations to the outer peripheral face22A of the reel hub22(seeFIG. 7).

Note that the recording tape T is wound onto the outer peripheral face22A of the reel hub22using the above-described winding method; however, the surface is rougher at the weld portions40than at non-weld portions44(between each weld portion40and weld portion40). Thus more abraded powder D than required is liable to be generated by the weld portions40. Moreover, the recording tape T has a thickness of 5.5 μm or less (5.2 μm in the present exemplary embodiment) and 1000 m or more is wound around the reel20, with there being a trend in the future towards even thinner recording tapes.

Thus, as illustrated inFIG. 8andFIG. 9, when the free end portion Tf of the recording tape T is adhered to the outer peripheral face22A of the reel hub22by the abraded powder D, and a winding start portion of a second turn of the recording tape T is superimposed on and wound around the free end portion Tf of a first turn of the recording tape T with the abraded powder D interposed between the recording tape T and the outer peripheral face22A, a step that is the thickness of the recording tape T or greater occurs at the winding start portion of the second turn of the recording tape T due to the abraded powder D, such that creasing is liable to occur in the recording tape T sequentially superimposed on the winding start portion.

When creasing occurs in the recording tape T, when the recording tape T has been run while rotating the reel20for a predetermined number of rotations, and the recording tape T has been recorded on or played back by a recording and playback head (not illustrated in the drawings) of the drive device, the behavior of the recording tape T at the portion where the creasing has occurred changes suddenly, such that there is a possibility of a recording defect or a playback defect, namely, of drop-out occurring in the recording and playback head.

Note that, in the present exemplary embodiment as described above, in order to reduce the surface roughness Ra of the weld portions40, the anticorrosion coating CT is applied to the wall face62A of the hub formation portion62that forms the outer peripheral face22A of the reel hub22. Specifically, a chromium nitride-based coating, or a diamond-like carbon (DLC) coating, for example, is applied to the wall face62A.

This enables the wall face62A of the hub formation portion62of the mold60to be suppressed or prevented from corroding over time during molding, thereby enabling the surface roughness Ra of the weld portions40including the weld lines42to be reduced. Specifically, a difference between the surface roughness Ra of the weld portions40and the surface roughness Ra of the non-weld portions44can be reduced to 0.25 μm, or less.

Thus, in the winding method in which the free end portion Tf of the recording tape T is wound on after being caused to make sliding-contact with and adhere to the outer peripheral face22A of the reel hub22, when the recording tape T is being wound around the outer peripheral face22A of the reel hub22, generation of more abraded powder D than required can be suppressed, and the step occurring due to the recording tape T being wound around can be reduced.

Specifically, obviously in cases of joining without employing the abraded powder D, but even in cases of joining employing the abraded powder D as illustrated inFIG. 9, a difference in winding radii We, Wf across the entire width of the recording tape T between a winding terminal end of the first turn and a winding start end of the second turn of the recording tape T that has been wound around the outer peripheral face22A of the reel hub22is 1.3 times the thickness of the recording tape T, or less. Creasing can be suppressed or prevented from occurring on the recording tape T within this range, and drop-out can be suppressed or prevented from occurring. Moreover, since the degree to which creasing occurs can be predicted, control that suppresses or prevents the occurrence of drop-out is possible.

Note that the anticorrosion coating CT is only applied to the wall face62A of the hub formation portion62. Namely, the anticorrosion coating CT is not applied to respective wall faces of the bottom plate formation portion68or the flange formation portion64, which respectively mold the bottom plate28and the lower flange24which demand dimensional accuracy.

The surface roughness Ra and winding radius in the present exemplary embodiment is measured by a contour/form measuring system CV-3000CNC (manufactured by Mitutoyo Corporation). In the case of winding radius, for example, the surface of the recording tape T from the vicinity of the winding terminal end of the first turn to the vicinity of the winding start end of the second turn is scanned around the circumferential direction of the reel hub22at an appropriate location along the axial direction of the reel hub22, and the difference in radii is derived from the acquired contour curve.

Second Exemplary Embodiment

Explanation follows regarding a reel20according to a second exemplary embodiment. Note that similar locations to the first exemplary embodiment are appended with the same reference numerals, and detailed explanation thereof (including common operation) is omitted as appropriate.

As illustrated inFIG. 10AandFIG. 10B, the reel20according to the second exemplary embodiment includes a circular shaped opening portion28A at the center portion of the bottom plate28(the axial center of the reel20), and three of the gate marks46are formed at equal intervals on top of the reel gear34formed to the lower face of the bottom plate28. Namely, as illustrated inFIG. 11, in the mold60for molding the reel component member30of this reel20, three of the gates66are disposed at equal intervals around the circumferential direction of the bottom plate formation portion68.

Melted resin material that is injected through the three gates66thereby converges together at the bottom plate formation portion68, and also converges together at the hub formation portion62and the flange formation portion64. Thus, similarly to in the first exemplary embodiment, weld portions40each including the weld line42are formed to the outer peripheral face22A of the reel hub22(seeFIG. 7).

Namely, in the first exemplary embodiment, the weld portions40are formed to the outer peripheral face22A of the reel hub22by the three column portions58provided to the bottom plate formation portion68at equal intervals around the circumferential direction, whereas in the second exemplary embodiment, the weld portions40are formed to the outer peripheral face22A of the reel hub22by disposing the three gates66at the bottom plate formation portion68at equal intervals around the circumferential direction. Thus, as illustrated inFIG. 11, it is effective to apply the anticorrosion coating CT to the wall face62A of the hub formation portion62of the mold60in this example also.

Third Exemplary Embodiment

Explanation follows regarding a reel20according to a third exemplary embodiment. Note that similar locations to the first exemplary embodiment and the second exemplary embodiment are appended with the same reference numerals, and detailed explanation thereof (including common operation) is omitted as appropriate.

The reel20according to the third exemplary embodiment includes the reel component member30molded using a mold (not illustrated in the drawings) in which the anticorrosion coating CT is not applied to the wall face62A of the hub formation portion62. The outer peripheral face22A of the reel hub22(the weld portions40in particular) is ground such that the difference between the surface roughness Ra of the weld portions40and the surface roughness Ra of the non-weld portions44is 0.25 μm, or less. Note that a mold60applied with the anticorrosion coating CT may be employed.

Explanation follows regarding an example of a grinder for grinding the outer peripheral face22A of the reel hub22. As illustrated inFIG. 12, the grinder includes a grinding member54that is configured capable of contacting and moving away from the outer peripheral face22A of the reel hub22. A recessed portion55with a circular arc shape in side view is formed to the grinding member54. The resilient body48is fixed by adhesion to the recessed portion55, and a dummy tape56used for grinding is fixed by adhesion to an upper face54A of the grinding member54, including an upper face of the resilient body48.

The outer peripheral face22A of the reel hub22is thereby ground as described below. First, the reel20is set on a rotary drive gear (not illustrated in the drawings) of the grinder. Namely, the reel gear34of the reel20is enmeshed with the rotary drive gear. Note that the reel plate36is attracted to a magnet (not illustrated in the drawings) provided at the radial direction inside of the rotary drive gear when this is performed. The grinding member54is then moved, and the dummy tape56presses against the outer peripheral face22A of the reel hub22.

Namely, the dummy tape56that is present on top of the resilient body48is caused to contact the outer peripheral face22A of the reel hub22with a predetermined pressure. The reel hub22is then rotated at a predetermined speed around the arrow A direction illustrated inFIG. 12. The outer peripheral face22A of the reel hub22(the weld portions40in particular) is thereby ground by the dummy tape56, thereby enabling the difference between the surface roughness Ra of the weld portions40and the surface roughness Ra of the non-weld portions44to be 0.25 μm, or less.

Thus, in the winding method in which the free end portion Tf of the recording tape T is caused to make sliding-contact with and adhere to the outer peripheral face22A of the reel hub22and then is wound thereon, when the recording tape T is wound around the outer peripheral face22A of the reel hub22, more of the abraded powder D than required can be suppressed from occurring (or configured such that substantially no abraded powder D occurs), and the step occurring due to the recording tape T being wound around can be reduced.

Note that it is preferable that at least the recessed portion55is formed in a curved face shape (a circular arc shape in side view) with a curvature of the outer peripheral face22A of the reel hub22, or less. This enables a contact surface area of the dummy tape56present on top of the resilient body48against the outer peripheral face22A of the reel hub22to be well secured. This enables the outer peripheral face22A of the reel hub22(the weld portions40in particular) to be efficiently ground.

Reels20according to the present exemplary embodiments have been explained above based on the drawings; however, the reels20according to the present exemplary embodiments are not limited to those illustrated, and the design may be modified as appropriate within a range not departing from the spirit of the present disclosure.

For example, the reel component member30configuring the reel20may be configured by the reel hub22, the upper flange26, and the bottom plate28. Moreover, a configuration may be applied in which the anticorrosion coating CT is only applied to parts (locations facing the weld lines42) of the wall face62A of the hub formation portion62. It is sufficient that there are plural of the hole portions38, or the gate marks46and the gates66, and the numbers thereof are not limited to the three illustrated in the drawings.