`
`rea
`Patentamt
`European
`Patent Office
`derbrevets
`
`""
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`(12)
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`Mt|||||||| |||||||||||||||ll
`(11)
`EP 1 098 320 B1
`
`EUROPEANPATENT SPECIFICATION
`
`(51) Int Cl.:
`G11B 23/107(2006.01)
`
`G11B 23/04 (2006.01)
`
`(45) Date of publication and mention
`of the grant of the patent:
`04.04.2007 Bulletin 2007/14
`
`(21) Application number: 00124448.2
`
`(22) Date offiling: 08.11.2000
`
`(54) Magnetic tape cartridge
`
`Magnetbandkassette
`
`Cassette a bande magnétique
`
`
`(84) Designated Contracting States:
`DE FR GB
`
`(30) Priority: 08.11.1999 JP 31716699
`09.11.1999 JP 31846499
`
`(43) Date of publication of application:
`09.05.2001 Bulletin 2001/19
`
`(60) Divisional application:
`04020872.0 / 1 492 112
`
`(73) Proprietor: FUJIFILM Corporation
`Minato-ku
`
`Tokyo(JP)
`
`Inventors:
`(72)
`¢ Takahashi, Daisuke,
`Fuji Photo Film Co., Ltd.
`Kanagawa-ken (JP)
`* Shiga, Hideaki,
`Fuji Photo Film Co., Ltd.
`Kanagawa-ken (JP)
`
`¢ Tsuyuki, Seiji,
`Fuji Photo Film Co., Ltd.
`Kanagawa-ken (JP)
`
`(74) Representative: Griinecker, Kinkeldey,
`Stockmair & Schwanhausser
`
`Anwaltssozietat
`Maximilianstrasse 58
`
`80538 Munchen (DE)
`
`(56) Referencescited:
`EP-A- 0 284 687
`
`EP-A- 1 054 403
`WO-A-97/15925
`
`US-A- 5 366 173
`
`EP-A- 0 926 676
`
`EP-A- 1 058 259
`WO-A-99/65032
`
`US-A- 5 901 916
`
`¢
`
`"Cartridge reel brake" IBM TECHNICAL
`DISCLOSUREBULLETIN,US,IBM CORP. NEW
`YORK,vol. 28, no. 10, March 1986 (1986-03), page
`4552 XP002099977 ISSN: 0018-8689
`
`EP1098320B1
`
`SONY Exhibit 1029
`SONY Exhibit 1029
`SONY v. FUJI
`SONYv. FUJI
`
`
`Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give
`notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in
`a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art.
`99(1) European Patent Convention).
`
`Printed by Jouve, 75001 PARIS (FR)
`
`

`

`1
`
`EP 1 098 320 B1
`
`2
`
`Description
`
`[0001] This invention relates to a magnetic tape car-
`tridge according to the preamble of independent claim 1.
`[0002] Asa recording medium for use in an external
`memory of a computer or the like, there has been known
`a magnetic tape cartridge comprising a magnetic tape
`wound around a single reel and a cartridge casing in
`which the reel is housed for rotation. Since the magnetic
`tape is used for storing data in a computer or the like and
`important information is stored on the magnetic tape, the
`magnetic tape cartridge is provided with a reel stopper
`means which prevents rotation of the reel when the mag-
`netic tape cartridge is not being used, e.g., when the mag-
`netic tape cartridge is being stored, so that trouble such
`as tape jam does not occur and the magnetic tapeis not
`accidentally drawn out.
`[0003] Thereel stoppermeans is provided with a brake
`member which is adapted to be engagedwiththe reel to
`preventrotation of the reel and is disengaged from the
`reel to permit rotation of the reel in response to a reel
`chucking action of the reel drive means of a tape drive
`such as an external memory when the magnetic tape
`cartridge is loaded in the tape drive.
`[0004]
`In order to improvereliability of the action of the
`reel stopper means and to prevent dust from entering the
`cartridge casing, the reel stopper means maybe, for in-
`stance, of a structure comprising a brake member which
`restricts rotation of the reel, an urging member which
`urges the brake member toward a locking position in
`which the brake member restricts rotation of the reel, and
`a release member which is movedin response to a reel
`chucking action of the reel drive means of a tape drive
`to move the brake member toward a release position in
`which the brake member releases the reel to permit ro-
`tation of the same.
`
`[0005] Thatis, when the magnetic tape cartridge is not
`being used, the brake member locks the reel so that the
`reel is not accidentally rotated and the magnetic tapeis
`not accidentally drawn out, and when the magnetic tape
`cartridge is loaded in a tape drive, the release member
`drives the brake member to release the reel in response
`to a reel chucking action of the reel drive means of the
`tape drive. In this state, the reel can be rotated and load-
`ing/unloading of the magnetic tape is permitted.
`[0006]
`In such a structure, it is advantageous in sim-
`plifying the structure that the release memberis adapted
`to be brought into abutment against a part of the reel
`drive means of the tape drive and the reel drive means
`pushesa part of the release member to drive the brake
`member to release the reel when the reel drive means
`
`chucksthe reel. However,in this case, when the release
`member drives the brake member to releasethe reel, the
`brake membercanbeinclined as shownin Figure 5 and
`the gear teeth on the brake member can be broughtinto
`contact with the rear teeth on the reel while the reel is
`
`rotated, which results in generation of noise, obstruction
`of rotation of the reel and unstable magnetic tape loading/
`
`unloading action.
`[0007] Asacauseof the brake memberbeinginclined,
`that the brake member becomesoff-centered and comes
`to be inclined when the brake member is moved to the
`
`locking position where the braking gear thereon is
`brought into engagementwith an engagement gear on
`the reel and the brake member is moved to the release
`
`position in this state can be conceived. Further,that the
`brake member wasincorporated in the magnetic tape
`cartridge inclined relative to the reel when the magnetic
`tape cartridge was assembled can be conceived.
`[0008] Whenthe braking gear teeth on the brake mem-
`ber are like sawteeth in shape and the surface of each
`tooth facing against the tape-unwinding direction of the
`reel is substantially normal, though rotation of the reel in
`the tape-unwinding direction can be surely prevented,
`there is fear that the magnetic tape is cut when the reel
`is rotated in the tape-winding direction due to drop impact
`when the magnetic tape cartridge drops.
`[0009] Thatis, when the braking gear and the engage-
`ment gear are engaged with each other at a substantially
`normal surface facing against the tape-unwinding direc-
`tion, the reel cannot be rotated in the tape-unwinding
`direction. Further, a leader member such asa leader pin
`is fixed to the end of the magnetic tape wound around
`the reel, and the leader member is held near the tape
`draw-out opening of the cartridge casing when the mag-
`netic tape cartridge is not being used. When the brake
`member is moved and the braking gear is disengaged
`from the engagement gear due to drop impact with the
`reel rotated in the tape-winding direction under inertia, a
`tape winding force acts on the magnetic tape whose end
`is fixed by the leader member. Since the reel cannot be
`rotated in the tape-unwinding direction or the direction in
`which the tension on the magnetic is released, the tape
`winding force acting on the magnetic tape can stretch
`the tape to deteriorate the magnetic recording and repro-
`ducing characteristics, remove the leader member from
`the magnetic tape, cut the magnetic tape, or displace the
`leader member from the predetermined position to disa-
`ble the regular tape draw-out action, thereby deteriorat-
`ing the reliability of the magnetic tape cartridge.
`[0010]
`From EP 0 926 676 A1 a magnetic tape car-
`tridge as indicated above is known, wherein the magnetic
`tape cartridge comprises a single reel, a casing anda
`reel stopper means. Here, the reel stopper means com-
`prises abrake member being movable up and down away
`from and towardsthe reel, an urging member urging the
`brake member towards the reel and a brake release
`
`member moving the brake member awayfrom the reel.
`The teeth of the brake member comprise, respectively,
`two abutment surfaces with an equal inclination, so that
`the teeth of the brake member could provide the same
`force on a single reel in both directions thereof, namely,
`winding and unwinding direction.
`[0011]
`EP 0 284 687 A2 discloses a tape cartridge
`comprising a spool, a brake button and projecting means
`with projections or centering ribs.
`
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`

`

`3
`
`EP 1 098 320 B1
`
`4
`
`[0012] WO 97 15925 Ai and US 5,901,916 A disclose
`atapecartridge comprising a housing, a tape supplyreel,
`reel gear and a reel lock, wherein the reel lock has been
`urged by a brake spring towards a locking meanspro-
`vided at the tape supply reel. Here, each of the teeth of
`the reel lock comprises equally inclined abutment sur-
`faces.
`
`following, the present invention is explained in greater
`detail by means of several embodiments thereof in con-
`junction with the accompanying drawings, wherein:
`
`Figure 1 is a perspective view showing a state of a
`magnetic tape cartridge in accordance with an em-
`bodimentof the present invention when the magnetic
`tape cartridge is not being used,
`Figure 2 is a fragmentary cross-sectional view of the
`magnetic tape cartridge shownin Figure 1 when the
`magnetic tape cartridge is being used,
`Figure 3 is a cross-sectional view taken along line
`A-A in Figure 2;
`Figure 4 is a cross-sectional view taken along line
`B-B in Figure 2, and
`Figure Sis a fragmentary cross-sectional view show-
`ing a state of a magnetic tape cartridge where the
`braking memberisinclined.
`
`It is an objective of the present invention to im-
`[0013]
`prove a magnetic tape coverage as indicated above so
`as to assure different forces applying from the brake
`member to the single reel in the winding and unwinding
`direction of the single reel.
`[0014] The objective is solved according to the present
`invention by amagnetic tape cartridge comprising a mag-
`netic tape wound around a single reel, a cartridge casing
`for housing the reel and a reel stopper means for locking
`the reel or permitting rotation thereof, wherein the reel
`stopper means comprises a braking member being
`moveable between a locking position anda releasing po-
`[0017] A magnetic tape cartridge 1 in accordance with
`sition, an urging member for urging the braking member
`an embodimentof the presentinvention will be described
`toward the locking position, and a releasing member be-
`with reference to the drawings, hereinbelow.
`ing rotated integrally with the reel for moving the braking
`member toward the releasing position in response to a
`[0018] The magnetic tape cartridge 1 comprises a car-
`
`reel chucking action of a reel drive means ofatapedrive, tridge casing 3 formed by fastening together upper and
`25
`and wherein the braking member is provided with a brak-
`lower casing halves 31 and 32 by screwsor the like. A
`ing gear comprising gear teeth being adapted to be en-
`single reel 2 around which a magnetic tape (not shown)
`gaged with at least one engagement gear tooth of an
`is wound is housed for rotation in the cartridge casing 3.
`engagementprojection formed on the reel, wherein each
`The lowercasing half 32 is provided with a central open-
`
`of the gear teeth of the braking gear comprisesafirst ing 32a. The magnetic tape cartridge 1 is further provided
`30
`inclined surface being directed towards a tape-unwinding
`with a reel stopper means 10 which permits rotation of
`direction and a second inclined surface being directed
`the reel 2 when the magnetic tape cartridge 1
`is being
`towards a tape-winding direction, wherein an interior an-
`used and restricts rotation of the reel 2 when the magnetic
`gle between the first inclined surface and a vertical is
`tape cartridge 1
`is not being used.
`smaller than an interior angle between the second in-
`[0019] The reel 2 comprises a reel hub 21 which is a
`clined surface and the vertical, and the inclined surfaces
`cylindrical member having a closed bottom and around
`form therebetween an apical angle being smaller than
`which the magnetic tape is wound, and lower and upper
`90°.
`flanges 22 and 23. The reel hub 21 and the lower flange
`22 are integrally formed by synthetic resin molding. The
`upper flange 23 is bonded to the reel hub 21, forinstance,
`by ultrasonic welding. The reel hub 21 is provided with a
`bottom wall 21a at the lower end portion thereof and a
`reel gear 24 for rotating the reel 2 is annularly formed on
`the lower surface of the bottom wall 21a, and annular
`reel plate 25 which is magnetically attracted by a reel
`drive means 11 of arecording and reproducing apparatus
`is mounted on the lower surface of the bottom wall 21a
`
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`inside the reel gear 24. The reel 2 is urged downward by
`an urging means5 to be described later.
`[0020] The reel drive means 11 is provided with an
`annulardrive gear 13 andamagnet (not shown) disposed
`onthe top surfaceof a rotary shaft 12. When the magnetic
`tape cartridge 1
`loaded in a bucketof the tape drive is
`moved downward toward the rotary shaft 12, the drive
`gear 13 is brought into mesh with the reel gear 24 and
`the reel plate 25 is magnetically attracted against the
`magnetto hold the drive gear 13 and the reel gear 24 in
`mesh with each other.
`In this manner, the reel drive
`means 11 chucksthe reel 2.
`
`[0015] According to the above mentioned, since the
`apical angle of the braking gear tooth is not larger than
`90° and theinterior angle for the first inclined surface of
`the braking gear tooth which is brought into abutment
`against the engagement gear teeth when the reel is ro-
`tated in the unwinding direction and the interior angle for
`the second inclined surface which is brought into abut-
`ment against the engagement gear teeth when the reel
`is rotated in the winding direction are not smaller than
`30° with the former smaller than the latter, rotation of the
`reel can be surely prevented and when the reel is rotated
`in the winding direction due to drop impact or the like and
`an excessive winding force acts on the magnetic tape,
`the braking member is moved toward the releasing po-
`sition along the first inclined surface and the braking gear
`is disengaged from the engagementgearteeth, whereby
`the reel is rotated in the unwinding direction to reduce
`the tension on the magnetic tape, and the magnetic tape
`can be prevented from being stretched or cut.
`[0016]
`Further preferred embodiments of the present
`invention are laid downin the further subclaims. In the
`
`

`

`5
`
`EP 1 098 320 B1
`
`6
`
`[0021] The mechanism of the reel stopper means 10
`will be described, hereinbelow. The reel stopper means
`10 comprises a braking member 4 which is movable up
`and down between alocking position whereitis in contact
`with the reel 2 to restrict rotation of the reel 2 and a re-
`
`ing gear 42 is brought into contact with the inclined sur-
`faces.
`
`[0026] As shownin Figure 4, each gear tooth of the
`braking gear 42 of the braking member 4 and each en-
`gagement gear tooth 29 on the engagementprojection
`27 are triangular in cross-section. The gear tooth of the
`leasing position whereit is away from the reel 2 to permit
`braking gear 42 hasa first inclined surface 42a which
`rotation of the same, an urging member 5 which urges
`faces against the tape-unwinding direction U and abuts
`the braking member 4 toward the locking position, anda
`againsta first inclined surface 29a of the engagement
`releasing member 6 which moves the braking member
`gear tooth 29 on the engagementprojection 27 which
`4 toward the releasing position.
`faces toward the tape-unwinding direction U, and a sec-
`[0022] As shownin Figure 3, three through holes 26
`ond inclined surface 42b which faces against the tape-
`are formedin the bottom wall 21a of the reel 2 at regular
`winding direction W and abuts against a second inclined
`angularintervals in the circumferential direction to extend
`surface 29b of the engagement gear tooth 29 on the en-
`through the portion at which the reel gear 24 is formed.
`gagementprojection 27 which faces toward the tape-
`On the upper surface of the bottom wall 21a, there are
`winding direction W. When the reel 2 is rotated in the
`erected three pairs of (six) engagementprojections 27
`tape-unwinding direction U with the braking gear 42 in
`at regularangularintervals in the circumferential direction
`mesh with the engagement gearteeth 29 on the engage-
`among the through holes 26. The upper end of each en-
`mentprojection 27, the first inclined surfaces 42a of the
`gagementprojection 27 is formed into an engagement
`gearteeth of the braking gear 42 are broughtinto abut-
`gear teeth 29 as shownin Figure 4. The through holes
`ment againstthe first inclined surfaces 29a of the en-
`26 maybe larger than three in number and the engage-
`gagementgear teeth 29, and when the reel 2 is rotated
`mentprojections 27 maybelarger three pairs in number.
`in the tape-winding direction W with the braking gear 42
`Further, the upper end of each engagementprojection
`27 may be formed into a single geartooth.
`in mesh with the engagement gear teeth 29 on the en-
`25
`
`[0023] The braking member 4 hasadisc portion 41 gagementprojection 27, the second inclined surfaces
`which is disposed in the reel hub 21 opposedto the bot-
`42b of the gear teeth of the braking gear 42 are brought
`tom wall 21a, and an annular braking gear 42 is formed
`into abutment against the second inclined surfaces 29b
`onthe lower surface of the disc portion 41 along the outer
`of the engagement gear teeth 29. Each of the gear tooth
`peripheral edge thereof. The braking gear 42 is adapted
`42 and the geartooth 29 is not larger than 90° in apical
`to be engaged with the engagement gear 29 on the en-
`angle y, and an interior angle @ between the first inclined
`gagementprojections 27. The central part of the lower
`surface 42a (or 29a) and a vertical S$ and an interior angle
`6 between the second inclined surface 42b (or 29b) and
`surface of the disc portion 41 is convex downward and
`the vertical S are not smallerthan 30°. Further, the interior
`forms a sliding portion 41a which is pressed against a
`sliding portion 61a on the upper surface of a body portion
`angle «for the first inclined surface 42a (29a)is not larger
`than the interior angle B for the second inclined surface
`61 of the releasing member 6 to be described later.
`[0024] An outer diameter D of the engagement gear
`42b (29b). That is, 60°Sy=90°, 30°=0.=45°, and 30°
`formed by the engagementgear teeth 29 on the engage-
`=B=60°.
`ment projections 27 onthe reel 2 (Figure 3)is larger than
`[0027] Aprojection 44 extends upward from the upper
`an outer diameter d (Figure 2) of the braking gear 42 on
`surface of the disc portion 41 of the braking member 4,
`the braking member 4. The braking gear 42 and the en-
`and across-shaped engagementgroove 45 is formed in
`gagement gear 29 are conical in shape and the height
`the projection 44 to extend in the vertical direction. An
`of each tooth is higher at the outer periphery thereof.
`engagementprojection 33 extending downward from the
`Accordingly, the braking gear 42 is engagedwith the en-
`inner surface of the upper casing half 31 of the cartridge
`gagementgear teeth 29 at their outer peripheriesfirst.
`casing 3 is in engagement with the engagement groove
`[0025] Whenthebraking gear 42 on the braking mem-
`45 of the braking member 4, whereby the braking mem-
`ber 4 is brought into mesh with the engagement gear 29
`ber 4 is held in the cartridge casing 3 to be movable up
`and downbut not to berotatable.
`on the engagementprojections 27, the outer periphery
`of the braking member 4 is guided by quide members 39
`formed on the inner surface of the reel hub 21 of the reel
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`[0028] A coiled spring (urging member) 5 is com-
`pressed between a portion of the upper surface of the
`disc portion 41 around the projection 44 and a spring
`retainer portion 34 formed on the upper casing half 31
`around the engagementprojection 33, whereby the brak-
`ing member 4 is urged toward the locking position where
`the braking gear 42 is engaged with the engagement
`gearteeth 29 on the engagementprojections 27.
`[0029] Thereleasing member 6 is disposed to be mov-
`able up and downbetween the braking member 4 and
`the bottom wall 21a of the reel hub 21 and comprisesthe
`
`2. The guide members 39 are respectively provided be-
`tween each pair of engagement projections 27, and ac-
`cordingly three guide members 39 are provided on the
`inner surface of the reel hub 21. Each guide member 39
`is in the form of a rib having an inclined surface which
`gradually inclines downward from the upper portion of
`the inner surface of the reel hub 21 toward the engage-
`ment projections 27, and the guide members 39 center
`the braking gear 42 when the outer periphery of the brak-
`
`

`

`7
`
`EP 1 098 320 B1
`
`8
`
`substantially triangular plate-like body portion 61. A cy-
`lindrical leg portion 63 extends downward from the lower
`surface of the body portion 61 at each corner thereof.
`The leg portions 63 are passed throughthe through holes
`26 in the bottom wall 21a of the reel 2 to be movable up
`and down. The engagement projections 27 are posi-
`tioned between the leg portions 63 outside the body por-
`tion 61 of the releasing member 6. The leg portions 63
`may also be rectangularor ellipsoidal in cross-section.
`[0030] When the releasing member 6 is in its lower-
`most position shown in Figure 1, the lower ends of the
`leg portions 63 project downward form the lower surface
`of the reel 2 through the portion at which the reel gear
`24 is formed, and when the drive gear 13 is broughtinto
`engagementwith the reel gear 24 in response to a chuck-
`ing action of the reel drive means 11, the leg portions 63
`are pushed upward by a predetermined stroke as shown
`in Figure 2, whereby the braking gear 42 of the braking
`member 4 is disengaged from the engagementgear teeth
`29 of the engagementprojections 27 and rotation of the
`reel 2 is permitted. Since the leg portions 63 are passed
`through the through holes 26 the releasing member 6 is
`rotated together with the reel 2.
`[0031] The reel 2 is provided with guide members 28
`(Figure 3) which guide the releasing member 6 when the
`leg portions 63 are inserted into the through holes 26.
`Each of the guide members 28 guides a corner of the
`body portion 61 of the releasing member 6 and comprises
`a pair of guide ribs formed on the inner surface of the
`reel hub 21 to extend in the vertical direction near one of
`
`the through holes 26. Reinforcing ribs like the guide ribs
`are provided on the entire inner surface of the reel hub 21.
`[0032] Operation of the reel stopper means 10 will be
`described, hereinbelow. Figure 1 showsa state of the
`magnetic tape cartridge 1 when it is not being used (e.g.,
`when it is stored).
`In the state shown in Figure 1, the
`braking member 4, the releasing member 6 and the reel
`2 are held in the lower casing half 32 of the cartridge
`casing 3 under the force of the urging member 5 and the
`central opening 32a of the lower casing half 32 is closed
`by the reel 2. The releasing member 6 is in its lowermost
`position where its lower surface is in abutment against
`the upper surface of the bottom wall 21a of the reel hub
`21 and the lower end portions of the leg portions 63
`project downward beyond the tips of the teeth ofthe reel
`gear 24. The braking member 4 is in abutment against
`the releasing member 6 and in its locking position where
`the braking gear 42 is in mesh with the engagement gear
`teeth 29 of the engagementprojections 27 on the reel 2,
`wherebyrotation of the reel 2 is restricted and the mag-
`netic tape is prevented from being drawn out.
`[0033] As shownin Figure 2, when the magnetic tape
`cartridge 1
`is loaded in a tape drive, the rotary shaft 12
`of the reel drive means 11 of the tape drive is moved
`toward the lower surface of the reel 2 and the drive gear
`13 is brought into mesh with the reel gear 24 with the reel
`2 slightly pushed upward, wherebythe leg portions 63 of
`the releasing member 6 are pushed upward bythe tips
`
`of the teeth of the drive gear 13. Thus, the releasing mem-
`ber 6 is moved upward overcoming the force of the urging
`member 5 and the braking member 4 is moved upward
`together with the releasing member 6, wherebythe brak-
`ing gear 42 is disengaged from the engagement gear
`teeth 29 of the engagementprojections 27 and rotation
`of the reel 2 is permitted. In this state, the braking member
`4 in its upper position is away from the guide members
`39 and doesnot restrict rotation of the reel 2 when the
`
`magnetic tape is loaded/unloaded.
`[0034] When the braking member 4 is moved down-
`ward from the releasing position to the locking position,
`the braking member 4 is centered by the guide members
`39 on the reel 2 so that the braking gear 42 is brought
`into mesh with the engagement gear teeth 29 with the
`braking member 4 held horizontal, whereby the braking
`member 4 is prevented from being inclined in the locking
`position. When the braking member 4 is subsequently
`moved upwardto the releasing position by the releasing
`member 6, the braking member 4 is held horizontal up
`to the releasing position. Accordingly, the phenomenon
`that the braking member 4 is inclined as shownin Figure
`5 can be suppressed, whereby the braking gear 42 is
`prevented from contacting the engagement gear teeth
`29 to generate noise or to obstruct rotation of the reel 2.
`Further, during assembly of the magnetic tape cartridge
`1, the braking member 4 is automatically centered in the
`reel hub 2 by the guide members 39 and is incorporated
`in place in the reel 2, whereby assembly of the magnetic
`tape cartridge 1 is facilitated.
`[0035]
`Even if the guide members 39 are not provided,
`since the outer diameter D of the engagement gear
`formed by the engagementgear teeth 29 on the engage-
`ment projections 27 on the reel2 is larger than the outer
`diameter d of the braking gear 42 on the braking member
`4, the braking member 4 is centered with respect to the
`reel hub 2 when it is moved from the releasing position
`to the locking position by virtue of the difference in diam-
`eter so that the braking gear 42 is brought into mesh with
`the engagementgear teeth 29 with the braking member
`4 held horizontal, whereby the braking member 4 is pre-
`vented from being inclined in the locking position.
`[0036]
`Further, when the reel 2 is rotated in the winding
`direction W due to drop impactor the like and an exces-
`sive winding force acts on the magnetic tape, the braking
`member 4 is moved upward along the first inclined sur-
`faces 42a and 29asincethe interior angles o for the first
`inclined surfaces 42a and 29a, which are brought into
`abutment against each other when the reel 2 is rotated
`in the unwinding direction U, are not smaller than 30°,
`and the braking gear 42 is disengaged from the engage-
`ment gear teeth 29, whereby the reel 2 is rotated in the
`unwinding direction U to reduce the tension on the mag-
`netic tape, and the magnetic tape can be prevented from
`being stretched or cut.
`[0037]
`Further, since the interior angles 6 for the sec-
`ond inclined surfaces 42b and 29b of the braking gear
`42 and the engagement gear teeth 29 are not smaller
`
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`

`9
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`EP 1 098 320 B1
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`10
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`than 30°, the reel 2 can be anyhowrotated even if the
`braking member 4 is in the locking position, though the
`rotation of the reel 2 is restricted. Accordingly, when the
`magnetic tape is accidentally drawn out from the car-
`tridge casing 3 during storageor the like of the magnetic
`tape cartridge 1, the magnetic tape can be rewound into
`the cartridge casing 3.
`[0038] The effect of reducing the tension on the mag-
`netic tape can be obtained when the interior angle « is
`not smaller than 30°. However when the interior angle «
`is larger than 45°, the locking force for preventing rotation
`ofthe reel 2 inthe unwinding direction becomes too weak.
`Thatis, in order to ensure both the effect of reducing the
`tension on the magnetic tape and the sufficient locking
`force, it is necessary that an apical angle y is not larger
`than 90° and the interior angles « for the first inclined
`surfaces 42a and 29a, which are brought into abutment
`against each other when the reel 2 is rotated in the un-
`winding direction U, are smaller than the interior angles
`B for the second inclined surfaces 42b and 29b which are
`brought into abutment against each other when the reel
`2 is rotated in the winding direction W.
`[0039] The height of the gear teeth of the braking gear
`42 and that of the engagement gear teeth 29 are set
`according to the distance between the locking position
`and the releasing position of the braking member 4. For
`a given height of the teeth, the number of the teeth is
`reduced andthe one-pitch length is increased as the api-
`cal angle yincreases. Accordingly, when the apical angle
`y is set not to be larger than 90°, the number of the gear
`teeth of the braking gear 42 is increased and the one-
`pitch length is reduced, whereby slack of the magnetic
`tape or the tension on the magnetic tape can be proper
`when the braking gear 42 is engaged with the engage-
`ment gear teeth 29.
`
`Claims
`
`surface (42a) being directed towards a tape-unwind-
`ing direction (U) and asecond inclined surface (42b)
`being directed towards a tape-winding direction (W),
`wherein an interior angle (o) between the first in-
`clined surface (42a) and a vertical (s) is smaller than
`an interior angle (3) between the secondinclined sur-
`face (42b) and the vertical (s), and the inclined sur-
`faces (42a,42b) form therebetween an apical angle
`(y) being smaller than 90°.
`
`2. A magnetic tape cartridge (1) according to claim 1,
`characterized in that the at least one engagement
`gear tooth (29) comprises a first and a second in-
`clined surface (29a,29b) being respectively corre-
`sponded to the first and second inclined surface
`(42a,42b) of the gear teeth of the braking gear (42).
`
`3. A magnetic tape cartridge (1) according to claim 1
`or 2, characterized in that the reel (2) is provided
`with a guide member (28,39) for centering the brak-
`ing member (4) with respect to the reel (2).
`
`4. A magnetic tape cartridge (1) according to claim 3,
`characterized in that the guide member (39) com-
`prises guide ribs being formed on an inner surface
`of a reel hub (21) at at least three places, wherein
`each guide ribs comprisesaninclined surfaceinclin-
`ing downward from an upper portion of the inner sur-
`face of the reel hub (21) toward a center of the reel
`(2).
`
`5. A magnetic tape cartridge (1) according to at least
`one of the claims 1 to 4, characterized in that an
`outer diameter (D) of an engagement gear compris-
`ing the at least one engagement geartooth (29)is
`larger than an outer diameter (d) of the braking gear
`(42).
`
`20
`
`25
`
`30
`
`35
`
`40
`
`Patentanspriiche
`
`1. Amagnetic tape cartridge (1) comprising a magnetic
`tape wound around a single reel (2), a cartridge cas-
`1. Magnetbandkassette (1), aufweisend ein um eine
`ing (3) for housing the reel (2) and a reel stopper
`Einzelspule (2) geschlungenes Magnetband, ein
`means (10) for locking the reel (2) or permitting ro-
`Kassettengehause(3) zum Unterbringen der Spule
`tation thereof, wherein the reel stopper means (10)
`(2) und eine Spulenanschlageinrichtung (10) zum
`comprises a braking member (4) being moveable
`Verriegeln der Spule (2) oder zum Gestatten der Dre-
`between a locking position and a releasing position,
`hung derselben, wobei die Spulenanschlageinrich-
`an urging member (5)for urging the braking member
`tung (10) ein Bremsteil (4) aufweist, das zwischen
`(4) toward the locking position, anda releasing mem-
`einer Verriegelungsposition und einer Freigabepo-
`ber (6) being rotated integrally with the reel (2) for
`sition bewegbar ist, ein Vorspannteil (6) zum Vor-
`moving the braking member (4) toward the releasing
`spannen des Bremsteils (4) in die Richtung zu der
`position in response to a reel chucking action of a
`Verriegelungsposition, und ein Freigabeteil (6), das
`reel drive means (11) of a tape drive, and wherein
`einstiickig mit der Spule (2) gedreht wird, zum Be-
`the braking member (4) is provided with a braking
`wegen des Bremsteils (4) in Richtung zu der Freiga-
`gear (42) comprising gear teeth being adapted to be
`beposition in Abhangigkeit von einer Spulenspann-
`engaged with at least one engagement gear tooth
`wirkung einer Spulenantriebseinrichtung (11) eines
`(29) of an engagementprojection (27) formed on the
`reel (2), characterized in that eachof the gearteeth
`Bandantriebs, und wobei das Bremsteil (4) mit einem
`
`of the braking gear (42) comprisesafirst inclined Bremszahnrad (42) versehen ist, das Zahnradzahne
`
`45
`
`50
`
`55
`
`

`

`11
`
`EP 1 098 320 B1
`
`12
`
`aufweist, die vorgesehen sind, um mit zumindestei-
`nem Eingriffszannradzahn (29) eines Eingriffsvor-
`sprungs (27), gebildet an der Spule (2) in Eingriff zu
`sein, dadurch gekennzeichnet, dass jedes der
`Zahnradzahne des Bremszahnrades (42) aufweist
`eine erste geneigte Oberflache (42a), die in die Rich-
`tung zu einer Bandabwicklungsrichtung (U) gerichtet
`ist und eine zweite geneigte Oberflache (42b), die in
`die Richtung zu einer Bandaufwickelrichtung (W) ge-
`richtet ist, wobei ein Innenwinkel (