(19) 0
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`)
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`European Patent Office
`Office européen des brevets
`
`HillliliiilliiiilliiilliiiiliililiiliililliiilliiiiillilliiliiilliiilHill
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`(11)
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`EP 0 926 676 A1
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`(12)
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`EUROPEAN PATENT APPLICATION
`
`(43) Date of publication:
`30.06.1999 Bulletin 1999/26
`
`(51) Int Cl.5: G11B 23l107, G11B 23/04
`
`(21) Application number: 98124712.5
`
`(22) Date of filing: 24.12.1998
`
`(84) Designated Contracting States:
`AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU
`MC NL PT SE
`
`Designated Extension States:
`AL LT LV MK RO SI
`
`9 Shiga, Hideaki, clo Fuji Photo Film Co., Ltd.,
`Kanagawa-ken (J P)
`9 Takahashi, Daisuke, clo Fuji Photo Film Co., Ltd.,
`Kanagawa-ken (J P)
`lshihara, Yusuke, clo Fuji Photo Film Co., Ltd.,
`Kanagawa-ken (J P)
`9 Tsuyuki, Seiji, clo Fuji Photo Film Co., Ltd.,
`Kanagawa-ken, (JP)
`
`9
`
`(74) Representative: Grflnecker, Kinkeldey,
`Stockmair & Schwanhéusser Anwaltssozietét
`Maximilianstrasse 58
`
`80538 Mfinchen (DE)
`
`
`uous wall portion of the reel hub.
`
`(30) Priority: 25.12.1997 JP 35672297
`
`(71) Applicant: FUJI PHOTO FILM CO., LTD.
`Kanagawa—ken, 250-01 (J P)
`
`(72) Inventors:
`9 Morita, Kiyoo clo Fuji Photo Film Co., Ltd.
`Odawara-shi, Kanagawa-ken (JP)
`
`(54) Magnetic tape cartridge
`
`A magnetic tape cartridge includes a cartridge
`(57)
`casing and a single reel which is contained in the car-
`tridge casing for rotation. The reel has a reel hub in the
`form of a cylindrical member which has a bottom wall
`and is provided with an opening and a stopper gear
`formed on the bottom wall. A brake member is provided
`with a brake gear and is movable up and down between
`an operative position where the brake gear is brought
`into engagement with the stopper gear to prevent rota-
`tion of the reel and a retracted position where the brake
`gear is disengaged from the stopper gear to permit ro-
`tation of the reel. The brake member is normally urged
`toward the operative position and moved tothe retracted
`position by a pusher member of a tape drive system
`which acts on the brake member through the opening in
`the reel hub when the magnetic tape cartridge is loaded
`in the tape drive system. A continuous wall portion is
`erected around the opening in the reel hub, and the
`brake member includes a horizontal portion and a con-
`tinuous skirt portion which extends downward from the
`horizontal portion and is in contact with the continuous
`wall portion of the reel hub to close the opening together
`with the horizontal portion. The brake member is moved
`between the operative position and the retracted posi-
`tion with the skirt portion kept in cotact with the contin-
`
`Printed by Jouve, 75001 PARIS (FR)
`
`21ft? 2“
`
`SONY Exhibit 1011
`SONY Exhibit 1011
`SONY v. FUJI
`SONY v. FUJI
`
`EP0926676A1
`
`

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`1
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`EP 0 926 676 A1
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`2
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`Description
`
`BACKGROUND OF THE INVENTION
`
`Field of the Invention
`
`[0001] This invention relates to a magnetic tape car-
`tridge, and more particularly to a magnetic tape car-
`tridge comprising a cartridge casing and a single reel
`around which a magnetic tape is wound and which is
`contained in the cartridge casing for rotation.
`
`Description of the Related Art
`
`[0002] There has been known a single reel magnetic
`tape cartridge, comprising a cartridge casing and a sin-
`gle reel around which a magnetic tape is wound and
`which is contained in the cartridge casing for rotation,
`as a recording medium for an external storage for a com-
`puter and the like. Such a single reel magnetic tape car-
`tridge is used for retaining important data of a computer
`or the like and accordingly is arranged so that trouble
`such as tape jamming does not occur and the magnetic
`tape is not accidentally drawn out.
`[0003] The reel is provided with a cylindrical reel hub
`having a closed bottom and stopper gear teeth are
`formed in a circle and a brake member provided with a
`brake gear which is adapted to be brought into engage-
`ment with the stopper gearteeth is disposed to be mov-
`able in the direction of thickness of the cartridge casing
`along the axis of rotation of the reel. The brake member
`is urged, for instance, by a coiled spring toward a posi-
`tion where the stopper gear teeth are engaged with the
`break gearto prevent rotation of the reel when the mag-
`netic tape cartridge is not used. When the magnetic tape
`cartridge is loaded in a recording and reproducing sys—
`tem, a brake release spindle of the recording and repro—
`ducing system pushes upward the brake member to dis—
`engage the stopper gear teeth from the brake gear.
`[0004] However if a space is formed between the
`brake member and the reel hub when the brake member
`
`is moved upward, dust and dirt can enter the inside of
`the cartridge casing through the space.
`
`SUMMARY OF THE INVENTION
`
`In view of the foregoing observations and de-
`[0005]
`scription, the primary object of the present invention is
`to provide a magnetic tape cartridge in which dust and
`dirt can be prevented from entering the inside ofthe car—
`tridge casing when the brake member is moved upward
`to permit rotation of the reel.
`[0006]
`In accordance with the present invention, there
`is provided a magnetic tape cartridge comprising a car-
`tridge casing, a single reel around which a magnetic
`tape is wound and which is contained in the cartridge
`casing for rotation, the reel having a reel hub in the form
`of a cylindrical member which has a bottom wall and is
`
`provided with an opening and a stopper gear formed on
`the bottom wall, and a brake member which is provided
`with a brake gear and is movable up and down between
`an operative position where the brake gear is brought
`into engagement with the stopper gear to prevent rota-
`tion of the reel and a retracted position where the brake
`gear is disengaged from the stopper gear to permit ro-
`tation of the reel,
`the brake member being normally
`urged toward the operative position and moved to the
`retracted position by a pusher member of a tape drive
`system which acts on the brake member through the
`opening in the reel hub when the magnetic tape car-
`tridge is loaded in the tape drive system,
`
`wherein the improvement comprises that
`a continuous wall portion is erected around the
`opening in the reel hub, and
`the brake member comprises a horizontal portion
`which is disposed above the opening in the reel hub
`and receives force from the pusher member when
`the brake member is movedtothe retracted position
`and a continuous skirt portion which extends down-
`ward from the horizontal portion and is in contact
`with the continuous wall portion of the reel hub,
`thereby closing the opening together with the hori—
`zontal portion, the brake member being moved be—
`tween the operative position and the retracted po-
`sition with the skirt portion kept in contact with the
`continuous wall portion of the reel hub.
`
`It is preferred that the brake member compris-
`[0007]
`es a first member and a second member which abuts
`
`against the first member from above and is movable up
`and down together with the first member, said horizontal
`portion and the skirt portion are formed on the first mem-
`ber and the brake member is urged toward the operative
`position by a spring means which acts on the second
`member.
`
`[0008] The skirt portion may be fitted either on or in
`the continuous wall portion.
`[0009]
`In the case where the brake member compris-
`es the first and second members, it is preferred that the
`first and second members abut against each other by
`way of a projection and the first and/or second members
`be formed of low friction hardwearing material.
`[0010]
`In the magnetic tape cartridge of the present
`invention, the skirt portion is kept in contact with the con-
`tinuous wall portion on the reel hub to keep the opening
`closed even when the brake member is in the retracted
`
`position, entrance of dust and dirt Into the cartridge cas—
`ing through the opening can be prevented.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
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`[0011]
`
`is an exploded perspective view of a mag-
`Figure 1
`netic tape cartridge in accordance with a first em-
`
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`EP 0 926 676 A1
`
`4
`
`bodiment of the present invention,
`Figure 2 is a side view of the first member of the
`brake member,
`Figure 3 is a side view of the second member of the
`brake member,
`Figure 4 is a fragmentary cross-sectional view
`showing an important part of the magnetic tape car-
`tridge of the first embodiment,
`Figure 5 is a fragmentary cross-sectional view
`showing a modification of the first embodiment,
`Figure 6 is a view similar to Figure 5 but showing
`another modification of the first embodiment,
`Figure 7 is a cross—sectional view of a magnetic tape
`cartridge in accordance with a second embodiment
`of the present invention in a state where the mag-
`netic tape cartridge is not used,
`Figure 8 is an exploded perspective view showing
`the reel stopper mechanism of the magnetic tape
`cartridge,
`Figure 9 is a fragmentary cross-sectional showing
`the magnetic tape cartridge in a state where it is
`used,
`Figure 10 is a fragmentary cross-sectional showing
`a modification of the magnetic tape cartridge of the
`second embodiment,
`Figure 11 is a view similar to Figure 8 but showing
`the reel stopper mechanism in a magnetic tape car-
`tridge in accordance with a third embodiment of the
`present invention,
`Figure 12 is a cross-sectional view of a magnetic
`tape cartridge in accordance with a fourth embodi-
`ment of the present invention in a state where the
`magnetic tape cartridge is not used,
`Figure 13 is an exploded perspective view showing
`the reel stopper mechanism of the magnetic tape
`cartridge,
`Figure 14 is a fragmentary cross—sectional showing
`the magnetic tape cartridge in a state where it is
`used,
`Figure 15 is a fragmentary cross-sectional view
`showing an example of the through hole and the
`push rod employed in the fourth embodiment,
`Figures 16A and 16B are fragmentary cross-sec-
`tional views showing another example of
`the
`through hole and the push rod employed in the
`fourth embodiment,
`Figure 17 is a fragmentary cross-sectional view
`showing still another example of the through hole
`employed in the fourth embodiment,
`Figure 18 is a fragmentary cross—sectional view
`showing still another example of the through hole
`and the push rod employed in the fourth embodi-
`ment,
`Figure 19 is a fragmentary cross-sectional view
`showing still another example of the through hole
`employed in the fourth embodiment,
`Figures 20 and 21 show modifications of the brake
`release member,
`
`Figures 22A and 22B are cross-sectional views
`showing modifications of the shapes of the push rod
`and the through hole,
`Figures 23A and 23B are cross-sectional views
`showing modifications of the shapes of the push rod
`and the through hole,
`Figure 24 is a cross-sectional view of a magnetic
`tape cartridge in accordance with a fifth embodi-
`ment of the present invention in a state where the
`magnetic tape cartridge is not used,
`Figure 25 is an exploded perspective view showing
`the reel stopper mechanism of the magnetic tape
`cartridge,
`Figure 26 is a cross—sectional view of a magnetic
`tape cartridge in accordance with a sixth embodi-
`ment of the present invention in a state where the
`magnetic tape cartridge is not used, and
`Figure 27 is an exploded perspective view showing
`the reel stopper mechanism of the magnetic tape
`cartridge.
`
`DESCRIPTION OF THE PREFERRED EMBODIMENT
`
`in ac-
`In Figure 1, a magnetic tape cartridge 1
`[0012]
`cordance with a first embodiment of the present inven—
`tion comprises a single reel 4 around which a magnetic
`tape 20 is wound and is contained for rotation in a car-
`tridge casing 7. The reel 4 is formed by bonding together
`a lower reel half 5 and an upper reel half 6 by ultrasonic
`welding. The cartridge casing 7 is formed by fastening
`together upper and lower casing halves 2 and 3 by
`screws and the like.
`
`[0013] The lower reel half 5 comprises a cylindrical
`hub 23 and a flange 24 which are integrally molded from
`synthetic resin. A reel plate 8 for magnetically connect-
`ing a drive mechanism of a recording and reproducing
`system is mounted on the outer bottom surface of the
`hub 23. Further on the inner bottom surface of the hub
`
`is formed a stopper gear 23A which is brought into
`23,
`engagement with a brake gear 32A formed on a brake
`member 30 to be described later and prevents rotation
`of the reel 4 when the magnetic tape cartridge 1
`is not
`used. The hub 23 is provided with an opening 238,
`through which a brake release spindle in the recording
`and reproducing system is inserted to push upward the
`brake member 30. An annular groove 23C in which the
`brake member 30 is fitted is formed around the opening
`238.
`
`[0014] The brake member 30 comprises a first mem—
`ber 31 having an annular protrusion 31A (Figure 2)
`which is fitted in annular groove 23C of the reel hub 23
`and a second member 32 having an annular protrusion
`which is projected downward as shown in Figure 3. The
`brake gear 32A is formed on the lower end face of the
`annular protrusion of the second member 32. A projec-
`tion 31 B is formed on the upper surface of the first mem-
`ber 31 and the second member 32 rests on the projec-
`tion 31 as shown in Figure 4. Furtheran exposed portion
`
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`

`5
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`EP 0 926 676 A1
`
`6
`
`31 C which is exposed outward through the opening 238
`of the reel hub 23 as shown in Figure 4 is formed on the
`lower surface of the first member 31. A projection 328
`which is like a cross in cross-section and is normally held
`in a groove 2A which is like a cross in cross-section and
`is formed on the inner surface of the upper casing half
`2 is provided on the upper surface of the second mem-
`ber 32.
`
`[0015] The brake member 30 is urged downward by
`a coiled spring 10 fitted on the projection 328 and is po-
`sitioned in the cartridge casing 8 with the annular pro-
`trusion 31A of the first member 31 received in the annu-
`
`lar groove 32C of the reel hub 23, with the brake gear
`32A and the stopper gear 23A in mesh with each other
`and with the projection 328 received in the groove 2A
`as shown in Figure 4. The height of the first member 31
`(the distance between the lower end face of the annular
`protrusion 32A and the top of the projection 31 B) is set
`so that the second member 32 rests on the projection
`31 B of the first member 31 and the brake gear 32A and
`the stopper gear 23A are in mesh with each other so
`long as the second member 32 is in a position as urged
`bythe coiled spring 10. Furtherthe height of the annular
`protrusion 31A of the first member 31 and the depth of
`the annular groove 230 of the reel hub 23 are set so
`that the annular protrusion 31A is still
`in the annular
`groove 23C even if the first member 31 is lifted to its
`uppermost position. Thefirstmember31 and/orthesec-
`ond member 32 is formed of low friction, hardwearing
`material such as polyoxymethylene, resin added with
`molybdenum or the like.
`[0016]
`In this state, rotation of the reel 4 is prevented
`by engagement between the brake gear 32A and the
`stopper gear 23A. When the magnetic tape cartridge 1
`is loaded in the recording and reproducing system, the
`brake release spindle of the recording and reproducing
`system pushes upward the exposed portion 31 C of the
`brake member 30, whereby the first and second mem—
`bers 31 and 32 of the brake member 30 are moved up-
`ward overcoming the force of the coiled spring 10 and
`the gears 32A and 23A are disengaged from each other
`to permit rotation of the reel 4. At this time, though the
`annular protrusion 31A of the first member 31 is moved
`upward relative to the annular groove 230 of the reel
`hub 23, the protrusion 31 A is not drawn out ofthe groove
`230 as described above.
`
`[0017] A tape outlet opening 26 through which the
`magnetic tape 20 is drawn out is formed in a side wall
`of the cartridge casing 7. The tape outlet opening 26 is
`closed and opened by a slide door 27 which is slidable
`in the directions of double-headed arrow A and is urged
`in the closing position by a spring not shown.
`[0018] A leader pin 21 is fixed to the leading end of
`the magnetic tape 20 and when the magnetic tape car-
`tridge 1
`is not used, the magnetic tape 20 is entirely
`wound around the reel 4 with the leader pin 21 held in
`a recess 28 formed near the tape outlet opening 26.
`[0019] When the magnetic tape cartridge 1
`is loaded
`
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`in a recording and reproducing system, the gears 23A
`and 32A of the hub 23 and the brake member 30 are
`
`disengaged from each otherto permit rotation of the reel
`4 in the manner described above and the drive mecha-
`
`nism of the recording and reproducing system holds the
`reel plate 8 under magnetic force and rotates the reel 4.
`At the same time, the slide door 27 is opened and the
`leader pin 21 is brought to a predetermined position in
`a tape running path, thereby recording or reproduction
`becomes feasible. In this state, since the annular pro-
`trusion 31A of the first member 31 is still in the annular
`
`groove 230, dust cannot enter the cartridge casing 7
`through the opening 238 of the reel hub 23.
`[0020]
`Since the annular protrusion 31 A is fitted in the
`annular groove 23C, the first member 31 is sometimes
`rotated relative to the second member 32 in response
`to rotation of the reel 4. In this particular embodiment,
`since the first member 31 is in contact with only at the
`projection 318, sliding resistance is small and genera-
`tion of wear tailings can be reduced. Further since the
`first member 31 and/orthe second member 32 is formed
`
`low friction, hardwearing material such as poly-
`of
`oxymethylene, sliding resistance is smaller and gener-
`ation of wear tailings can be more reduced.
`[0021] Though,
`in the first embodiment described
`above, the groove 23C is formed in the reel hub 23 and
`the protrusion 31A of the first member 31 is fitted in the
`groove 230, an annular wall portion 23D may be formed
`around the opening 238 as shown in Figure 5, and the
`annular protrusion 31 A may be fitted on the annular wall
`portion 23D. Otherwise an annular wall portion 23E may
`be formed around the opening 238 and the annular pro-
`trusion 31 A may be fitted in the annular wall portion 23E
`as shown in Figure 6. In this case, it is preferred that an
`annular flange 23F be provided to project inward from
`the annular wall portion 23E, thereby preventing the first
`member 31 from falling down through the opening 238.
`[0022]
`Further, though,
`in the first embodiment de—
`scribed above,
`the first member 31 is
`in abutment
`against the second member 32 at the projection 318
`formed on the first member 31, such a projection may
`be formed on the second member 32 or on each of the
`first and second members 31 and 32.
`
`A magnetic tape cartridge in accordance with
`[0023]
`a second embodiment of the present invention will be
`described with reference to Figures 7 to 9, hereinbelow.
`[0024]
`In Figure 7, the magnetic tape cartridge 101 of
`the second embodiment comprises a single reel 102
`around which a magnetic tape (not shown) is wound and
`is contained for rotation in a cartridge casing 103. The
`cartridge casing 103 is formed by fastening together up-
`per and lower casing halves 131 and 132 by screws and
`the like. The lower casing half 132 is provided with a
`central opening 132a. Further the magnetic tape car-
`tridge 101 is provided with a reel stopper means 110
`which prevents rotation of the reel 102 when the mag-
`netic tape cartridge 101 is not used and permits rotation
`of the reel 102 when the magnetic tape cartridge 101 is
`
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`7
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`EP 0 926 676 A1
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`8
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`used.
`
`[0025] The reel 102 comprises a reel hub 121 which
`is a cylindrical member having a bottom wall 121a and
`doughnut-shaped lower and upper flanges 122 and 123
`extending outward from the lower and upper ends of the
`reel hub 121 . The reel hub 121 and the lowerflange 122
`are formed integrally with each other by molding of syn-
`thetic resin and the upper flange 123 is fixed to the reel
`hub 121, for instance, by ultrasonic welding. Gearteeth
`(reel gear) 124 for driving the reel 102 are formed in a
`circle on the lower surface of the bottom wall 121a of
`
`the reel hub 121 and an annular reel plate 125 of mag-
`netic metal is mounted on the lower surface of the bot—
`
`tom wall 121a inside the reel gear 124. The reel gear
`124 and the reel plate 125 are exposed outside through
`the central opening 132a in the cartridge casing 132.
`The reel 102 is urged downward by an urging member
`105 to be described later.
`
`[0026] A reel drive means 111 of a tape drive system
`comprises a rotaw spindle 112 provided with a drive
`gear 11 3formed on the upper end face ofthe rotary spin-
`dle 112 and a magnet disposed on the upper end face
`of the same. When the magnetic tape cartridge 101 is
`loaded in the tape drive system, the rotary spindle 111
`is moved upward toward the magnetic tape cartridge
`101 and the drive gear 113 is brought into mesh with the
`reel gear 124 while the magnet attracts the reel plate
`125 to hold the drive gear 113 in mesh with the reel gear
`124.
`
`[0027] The reel stopper means 110 comprises a brake
`member 104 which is movable up and down away from
`and toward the reel 102, an urging member 105 which
`urges the brake member 104 toward the reel 102 and a
`brake release member 106 which moves the brake
`
`member away from the reel 102.
`[0028] As shown in Figure 8, three through holes 126
`are formed in the bottom wall 121a of the reel hub 121
`
`at regular intervals on a circle to extend through the bot—
`tom wall 121a at the portion where the reel gear 124 is
`formed. Further three engagement projections 127 are
`erected from the upper surface of the bottom wall 121a
`at regular intervals on a circle in positions angularly
`spaced from the through holes 126. The number of the
`through holes 126 and the engagement projections 127
`need not be limited tothree but for or more through holes
`126 and engagement projections 127 may be formed.
`The upper end portion of each engagement projection
`127 is shaped like a gear tooth and may be shaped like
`a plurality of gear teeth. In Figure 8, only the bottom wall
`121a of the reel hub 121 is shown as the reel 102.
`
`[0029] The brake member 104 is a substantially disc-
`like member and is disposed in the reel hub 121 op-
`posed to the bottom wall 121a of the reel hub 121. A
`plurality of gear teeth 141 (stopper gear) are annularly
`formed on the lower surface of the brake member 104
`
`member 104 and is fitted in a guide groove formed in a
`guide portion 131a projecting downward from the inner
`surface of the upper casing half 131 , whereby the brake
`member 104 is able to be moved toward and away from
`the bottom wall 121 a of the reel hub 121 without rotating
`relative to the reel hub 121. The protrusion 142 and the
`groove in the guide portion 131a may be like a cross in
`cross-section.
`
`[0030] An urging member 105 in the form of a coiled
`spring compressed between the upper surface of the
`brake member 104 urges the brake member 104toward
`the operative position where the stopper gear 141 and
`the engagement projections 127 are engaged with each
`other to prevent rotation of the reel 104.
`[0031] The brake release member 106 is disposed
`between the brake member 104 and the bottom wall
`
`121a of the reel hub 121 to be movable up and down.
`As shown in Figure 8, the brake release member 106
`comprises a central disc portion 161 and three arms 162
`extending radially outward from the central disc portion
`161. A rectangular push rod 163 extends downward
`from the free end of each arm 162 and is inserted for up
`and down movement into one of the through holes 126
`formed in the bottom wall 121a of the reel hub 121 with
`
`its lower end projected into teeth portion of the reel gear
`124 on the lower surface of the reel hub 121. The en—
`
`gagement projections 127 are positioned between the
`arms 162.
`
`In the lowermost position of the brake release
`[0032]
`member 106 shown in Figure 7, the lower end face of
`each push rod 163 is positioned substantially flush with
`the tips of the teeth of the reel gear 1 24 and, in response
`to chucking action of the rotary spindle 111 of the tape
`drive system for bringing the drive gear 113 into mesh
`with the reel gear 124, the push rods 163 are pushed
`upward to move upward the brake release member 106
`by a predetermined amount, thereby disengaging the
`engagement projection 127 from the stopper gear 141
`to permit rotation of the reel 102 as shown in Figure 9.
`Since the push rods 163 are inserted into the through
`holes 126 in the reel hub 121 , the brake release member
`106 is rotated integrally with the reel 102.
`[0033] The brake member 104 is urged downward by
`the urging means 105 so that the lower surface thereof
`abuts against the upper surface of the brake release
`member 106. A spherical projection 164 is formed on
`the upper surface of the central disc portion 161 coaxi-
`ally with the axis of rotation ofthe brake release member
`106, and a recess 143 having a curved bottom is formed
`on the lower surface of the brake member 104 so that
`
`the tip of the spherical projection 164 abuts against the
`center of the recess 143. Further an annular protrusion
`165 is formed on the upper surface of the brake release
`member 106 around the spherical projection 164 and
`the lower surface of
`the brake member 104 abuts
`
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`and are adapted to be brought into engagement with the
`engagement projections 127. A straight protrusion 142
`extends upward from the upper surface of the brake
`
`against the upper surface of the protrusion 165. Thus
`the brake member 104 and the brake release member
`
`106 contact each other over a limited area, whereby the
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`EP 0 926 676 A1
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`10
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`resistance to rotation of the reel 102 is reduced and gen-
`eration of wear talllngs can be suppressed.
`[0034] As shown in Figure 8, a plurality of slits 165a
`are formed in the annular protrusion 165 at predeter-
`mined intervals. Wear tailings generated between the
`contact surfaces ofthe brake member 104 and the brake
`
`release member 106 are gathered in the slits 165a so
`that the wear tailings are not held between the contact
`surfaces to promote wear.
`[0035] Though, in the embodiment described above,
`the projection 164 and the protrusion 165 are formed on
`the brake release member 106, they may be formed on
`the brake member 104. Further only one of the projec—
`tion 164 and the protrusion 165 may be formed. Since
`the peripheral speed increases toward the outer periph-
`ery of the central disc portion 161, it is preferred that the
`annular protrusion 165 be formed nearer to the center
`of the disc portion 161.
`[0036]
`In the modification of the second embodiment
`shown in Figure 10, the brake release member 106 con-
`tacts the brake member 104 at a ball 150 which is press-
`fitted in a recess formed on the upper surface of the
`brake release member 106 and is received in a recess
`144 formed in the lower surface of the brake member
`
`104. It is preferred that the ball 150 be formed hardwear—
`ing material such as steel or ceramics.
`[0037]
`It
`is preferred that at least one of the brake
`member 104 and the brake release member 106 be
`
`formed of lowfrlction, hardwearing material. For exam-
`ple, the brake member 104 is formed of polyoxymethyl-
`ene while the brake release member 106 is formed of
`
`polycarbonate resin, polycarbonate resin added with
`graphite, ABS resin, ABS resin added with graphite, or
`nylon resin added with molybdenum.
`[0038]
`Further, as clearly shown in Figure 8, the pro-
`trusion 142 extends long substantially across the upper
`surface of the brake member 104 and accordingly the
`coiled spring 105 fitted on the protrusion 142 is large in
`diameter. That is, the coiled spring 105 acts on the brake
`member 104 at a portion near the outer periphery of the
`brake member 104. Accordingly the coiled spring 105
`acts on the brake member 104 at a portion nearthe push
`rods 163 which are pushed upward by the rotary spindle
`111 of the tape drive system. With this arrangement, de-
`formation of the brake member 104, especially of the
`arms 162, can be suppressed, wherebythe brake mem-
`ber 104 can be smoothly lifted without friction between
`the outer surface of the push rod 163 and the inner sur—
`face of the through hole126. Since the thickness of the
`brake member 104, especially of the arms 162,
`is re—
`stricted, the brake member 104 is apt to be deformed
`when the working point at which the coiled spring 105
`acts on the brake member 104 is remote from the work-
`
`ing point at which the upward force transmitted from the
`rotary spindle 111 by way of the push rods 163 acts on
`the brake member 104. When the brake member 104 is
`
`the push rods 163
`the outer surface of
`deformed,
`brought into contact with the inner surface of the through
`
`holes 126 and friction therebetween adversely affects
`the brake release operation.
`[0039] A magnetic tape cartridge in accordance with
`a third embodiment of the present invention will be de-
`scribed with reference to Figure 11, hereinbelow.
`[0040] The magnetic tape cartridge of the third em-
`bodiment is substantially the same as the second em-
`bodiment, and accordingly the elements analogous to
`those in the second embodiment are given the same ref-
`erence numerals and only the difference from the sec-
`ond embodiment will be mainly described. Figure 11 is
`a view similar to Figure 8 but showing the reel stopper
`mechanism in the third embodiment.
`
`[0041] As shown in Figure 11, in this embodiment, ro—
`tation of the reel 102 is prevented by engagement of an
`external bevel gear 141' which is formed on the brake
`member 104 to conically taper toward the reel hub 121
`and an internal bevel gear 127' which is formed on the
`reel hub 121 to conically flare toward the brake member
`104. The internal bevel gear 127' is partly cutaway and
`the through holes 126 into which the push rods 163 of
`the brake release member 106 are inserted are formed
`
`at the cutaway portions.
`[0042]
`In this embodiment, since rotation of the reel
`102 is prevented by engagement of the conical gears
`141 ' and 1 27' and theformer is pressed againstthe latter
`by the urging means, the brake member 104 is centered
`with respect to the reel hub 121 so that the centerof the
`brake member 104 is on the axis of rotation of the reel
`
`102 and the gears 141' and 127' are engaged with each
`other under a uniform pressure over the entire periphery
`thereof, whereby rotation of the reel 102 can be surely
`prevented. Furtherforthe same reason, the brake mem-
`ber 104 can be lifted keeping the horizontal position by
`the spherical projection 164 when the push rods 163 are
`pushed downward and the gear 141' can be surely dis—
`engaged from the gear 127' over the entire periphery
`thereof.
`
`[0043] Rotation of the reel 102 may be prevented by
`pressing a high friction conical surface on the brake
`member 104 against a high friction conical surface on
`the reel hub 121.
`
`[0044] A magnetic tape cartridge in accordance with
`afourth embodiment of the present invention will be de-
`scribed, hereinbelow.
`[0045] As shown in Figure 12, the magnetic tape car-
`tridge 201 of the fourth embodiment comprises a single
`reel 202 around which a magnetic tape (not shown) is
`wound and is contained for rotation in a cartridge casing
`203. The cartridge casing 203 is formed by fastening
`together upper and lower casing halves 231 and 232 by
`screws and the like. The lower casing half 232 is pro-
`vided with a central opening 232a. Furtherthe magnetic
`tape cartridge 201 is provided with a reel stopper means
`210 which prevents rotation of the reel 202 when the
`magnetic tape cartridge 201 is not used and permits ro-
`tation of the reel 202 when the magnetic tape cartridge
`201 is used.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`

`

`11
`
`EP0926 676 A1
`
`12
`
`[0046] The reel 202 comprises a reel hub 221 which
`is a cylindrical member having a bottom wall 221a and
`doughnut-shaped lower and upper flanges 222 and 223
`extending outward from the lower and upper ends of the
`reel hub 221 . The reel hub 221 and the lowerflange 222
`are formed integrally with each other by molding of syn-
`thetic resin and the upper flange 223 is fixed to the reel
`hub 221, for instance, by ultrasonic welding. Gear teeth
`(reel gear) 224 for driving the reel 202 are formed in a
`circle on the lower surface of the bottom wall 221a of
`
`the reel hub 221 and an annular reel plate 225 of mag-
`netic metal is mounted on the lower surface of the bot-
`
`tom wall 221a inside the reel gear 224. The reel gear
`224 and the reel plate 225 are exposed outside through
`the central opening 232a in the cartridge casing 232.
`The reel 202 is urged downward by an urging member
`205 to be described later.
`
`[0047] When the magnetic tape cartridge 201 is load-
`ed in the tape drive system, the rotary spindle 111 is
`moved upward toward the magnetic tape cartridge 201
`and the drive gear 11 3 is brought into mesh with the reel
`gear 224 while the magnet attracts the reel plate 225 to
`hold the drive gear 113