WO1995031810A1 - Boitier de videocassette comportant une zone de regulation de relachement amelioree - Google Patents

Boitier de videocassette comportant une zone de regulation de relachement amelioree Download PDF

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Publication number
WO1995031810A1
WO1995031810A1 PCT/US1995/004015 US9504015W WO9531810A1 WO 1995031810 A1 WO1995031810 A1 WO 1995031810A1 US 9504015 W US9504015 W US 9504015W WO 9531810 A1 WO9531810 A1 WO 9531810A1
Authority
WO
WIPO (PCT)
Prior art keywords
reel
wall
tape
cassette
slack
Prior art date
Application number
PCT/US1995/004015
Other languages
English (en)
Inventor
Vincent P. Teuber
Original Assignee
Minnesota Mining And Manufacturing Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Minnesota Mining And Manufacturing Company filed Critical Minnesota Mining And Manufacturing Company
Publication of WO1995031810A1 publication Critical patent/WO1995031810A1/fr

Links

Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B23/00—Record carriers not specific to the method of recording or reproducing; Accessories, e.g. containers, specially adapted for co-operation with the recording or reproducing apparatus ; Intermediate mediums; Apparatus or processes specially adapted for their manufacture
    • G11B23/02—Containers; Storing means both adapted to cooperate with the recording or reproducing means
    • G11B23/04—Magazines; Cassettes for webs or filaments
    • G11B23/041—Details
    • G11B23/043—Brakes for tapes or tape reels
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B23/00—Record carriers not specific to the method of recording or reproducing; Accessories, e.g. containers, specially adapted for co-operation with the recording or reproducing apparatus ; Intermediate mediums; Apparatus or processes specially adapted for their manufacture
    • G11B23/02—Containers; Storing means both adapted to cooperate with the recording or reproducing means
    • G11B23/04—Magazines; Cassettes for webs or filaments
    • G11B23/08—Magazines; Cassettes for webs or filaments for housing webs or filaments having two distinct ends
    • G11B23/087—Magazines; Cassettes for webs or filaments for housing webs or filaments having two distinct ends using two different reels or cores
    • G11B23/08707—Details
    • G11B23/08721—Brakes for tapes or tape reels

Definitions

  • the present invention relates to magnetic tape cassettes. More particularly, the present invention relates to a slack limiter area for videocassettes which improves operation of the slack limiter.
  • Videocassettes typically include two reels mounted within a housing with a length of magnetic tape wound around the two reels and extending between the reels across an access opening. Slack or looseness in the tape between the reels can arise when the cassette is transported or is separated from its associated recording or reproducing device.
  • cassettes typically have locks which restrict rotation of the reels when the cassette is not in the recorder, it is still possible for one or both of the reels within the cassette housing to turn, unwind the tape and develop slack in the portion of the tape extending between the reels. This can happen, for example, when the cassette is in the recording or reproducing device and the reel locks have been released and the tape is being pulled from the cassette for engagement with a rotary recording head.
  • Slack in the tape can also occur when the tape is engaged with the recorder if driving and braking the reels during the operation of the recorder is not performed synchronously and at the same rate. This slack can cause the tape to jam within the cassette housing or within the recorder and can lead to defective recording or playing operations.
  • U.S. Patent No. 4,813,628 discloses a tubular slack limiter.
  • U.S. Patent Nos. 4,773,615, 4,639,967, 4,598,329, 4,569,492, 4,518,135, 4,405,097, and 4,382,565 all disclose slack limiters having a generally common configuration.
  • These slack limiters include a resilient, flexible strip which is generally made of a plastic material. The strip is fixed at one end to the cassette housing and has a free end which can include a layer of low friction material such as polytetrafluoroethylene and which contacts the tape.
  • slack limiters also known as wiper tabs
  • wiper tabs operate by pressing the tape against a stationary portion of the cassette housing, such as a guide pin, and frictionally preventing the tape from unwinding from the reel and developing slack.
  • These slack limiters have resilient portions which contact and provide a required force on the tape.
  • the slack limiters must be formed from materials other than the material of the cassette housing itself.
  • the pressure-applying slack limiter is typically not molded directly into the cassette housing and must be attached as a separate part after forming the housing.
  • One attachment method involves engaging a notch of the slack limiter with a projection on the housing.
  • slack limiters incorporate several features which have proven desirable. In particular, these slack limiters are typically oriented such that the portion of the slack limiter strip near the end which contacts the tape is nearly parallel to the tape. Further, it is common practice to provide a solid post or other member on the side of the tape opposite the slack limiter, against which the slack limiter presses the tape, to hold the tape more firmly and limit the motion of the slack limiter.
  • the tape path is such that when the tape is in forward motion, the tension in the tape pulls it away from the post, limiting wear on the side of the tape which contacts the solid member.
  • the slack limiter it is desirable for the slack limiter to contact the tape with the lightest possible pressure which will still achieve the desired function of limiting excess tape slack.
  • a problem which has arisen in certain tape cassettes, such as the Betacam-L, however, is that there is insufficient room within the cassette for a slack limiter tab having this combination of features.
  • Figure l shows a portion of a Betacam-L tape cassette in the region of the slack limiter tab.
  • the cassette 10 includes tape 12 which is wrapped around a tape reel 14 and passes around a roller 16 and a post 18 on its way toward the other tape reel where it passes around another post and roller before winding on that reel.
  • a slack limiter tab 20 is mounted in a tab enclosure 22 which includes three walls 24, 26, 28, and a cylindrical wall 30 which is attached directly to the wall 24, and indirectly to the wall 28 through a connecting wall 32.
  • the enclosure includes a corner 34 which receives one end of the slack limiter.
  • the slack limiter 20 is shown in Figure 2.
  • the slack limiter includes an attaching edge 36 and a contact edge 38.
  • a low friction material may be placed adjacent the contact edge 38 to form a low friction end 40.
  • a notch 42 defines a resilient portion 44 of the slack limiter 20 between the notch 42 and the contact edge 38.
  • the notch 42 receives the connecting wall 32 when the slack limiter 20 is mounted in the enclosure 22 with the attaching edge 36 received in the corner 34 to hold the slack limiter in place.
  • the tape path and general cassette configuration are specified by standards agreed upon by manufacturers of various portions of the system.
  • the slack limiter 20 is constrained to contact the tape 12 in the region between the roller 16 and the post 18.
  • This slack limiter operates by pressing the tape in a free span between the guide sleeve and the guide roller when tape is in tension, such as during operation when the tape spools between reels.
  • the contact edge 38 of the slack limiter 20 contacts the tape 12 at a point which is as near as practicable to the post 18, space does not permit an end portion 40 of the slack limiter 20 to be oriented parallel, or even nearly parallel, to the tape 12.
  • Angle A is actually quite large.
  • the slack limiter 20 When the tape 12 is moving in the forward direction shown by the arrow in Figure 1, the slack limiter 20 is in a tension or trailing edge mode, since the frictional force of the tape 12 on the end portion 40 places the resilient portion 44 in tension, and the contact edge 38 is a trailing edge, relative to the forward tape direction. Any protrusions on the tape 12 encountered by the contact edge 38 will simply cause the slack limiter 20 to lift away from the tape and wipe over the protrusion.
  • the slack limiter 20 when the tape 12 is moving in a reverse direction, the slack limiter 20 is in a compression or leading edge mode, since the contact edge 38 is a leading edge and the resilient portion 44 is loaded in compression. In this mode, any protrusion can catch the leading contact edge 38, buckle the resilient portion 44 and drag the end portion 40 to position 40'.
  • a commonly occurring protrusion in magnetic cassette tapes is the splice between the leader and the tape.
  • a typical adhesive for attaching the leader to the tape 12 is pressure-sensitive splicing tape. Since the splice is of finite thickness, it is possible that it may catch the contact edge 38 of the slack limiter 20.
  • the slack limiter 20 is then located inside of the guide roller and will not function as a slack limiter. Once in this position, the slack limiter will not shift back to its proper position. Also, the slack limiter could catch on the reel lock notches and cause severe noise, called motorboating, due to the slack limiter 20 being repeatedly hit by the teeth 46 of the reel 14. In this position, the slack limiter could also create a cassette jam.
  • a known method for preventing the splice from dragging the slack limiter 20 into the buckled and flopped over position a phenomenon which will be called tab flopover, is to assure that all splices are very streamlined, or at least well pressed down, to avoid a protruding edge which might catch the contact edge 38.
  • tab flopover a phenomenon which will be called tab flopover
  • Each reel has a forward direction and a reverse direction.
  • the forward direction corresponds to the play or fast forward modes and the reverse direction corresponds to the reverse mode.
  • the reverse direction corresponds to the reverse mode.
  • these direction-mode correspondences are reversed. Whenever the tape is moving between reels, one reel will see the tape moving forward and the other reel will see the tape moving in reverse. Thus, every time the tape moves, there is a danger of dislocating the slack limiter 20.
  • This invention involves a system for preventing flopover of a slack limiting tab in a videocassette when the tape is running in the reverse direction. Buckling of the resilient portion of the slack limiting tab is limited by a constraining wall which the tab engages if the leading edge of the tab catches a protrusion on the tape.
  • the constraining wall allows the tab to move a limited distance in the direction of tape transport while the contact end of the tab and the tape itself reorient to positions which eventually allow the tab to ride over the protrusion without tab flopover.
  • the invention is especially useful in preventing tab flopover caused by excessively protruding leader-to-tape splices, thereby allowing greater latitude in the splicing process.
  • the videocassette base includes two reel walls which each defines a respective reel area.
  • Each slack limiter is located adjacent the respective reel wall, and each reel wall extends from a central area toward the adjacent side wall for such a distance that it extends sufficiently toward the front of the cover to prevent the slack limiter from bending past the tape guide roller.
  • the reel walls and their extended portions are located on the cover.
  • the reel walls and extended portions are located on both the base and the cover.
  • Each reel wall can be the same height as the side walls for its entire length or can include a portion extending beyond a respective connecting wall that is higher than the side walls and extends for substantially the entire height of the assembled cassette.
  • Figure 1 is a partial top view of a slack limiter tab installed in a known Betacam-L videocassette.
  • Figure 2 a perspective view of a slack limiter tab before installation in a videocassette.
  • Figure 3 is a partial top view similar to Figure 1 showing the phenomenon of tab flopover due to an excessively protruding splice.
  • Figure 4 is a partial top view of a slack limiter installed in a videocassette base of the present invention having a constraining wall.
  • Figure 5 is a perspective view of the entire videocassette of Figure 4.
  • Figure 6 is a partial perspective view of the cover of the video cassette showing one embodiment of the present invention.
  • Figure 7 is a partial perspective view of the base of the video cassette showing another embodiment of the present invention.
  • Figure 8 is a partial perspective exploded view of the cover and base of the video cassette showing another embodiment of the present invention.
  • FIG 4 shows a portion of a Betacam-L tape cassette according to one embodiment of the present invention in the region of the slack limiter tab.
  • the cassette 10 includes tape 12 which is wrapped around a tape reel 14 and passes around two tape guides on its way toward the other tape reel where it passes around another post and roller before winding on that reel.
  • one tape guide is a roller 16 and the other is a post 18.
  • the guide post can be formed as a post molded as part of the base or cover or as a sleeve made of a separate material.
  • the sleeve can stand alone or can be a cylinder mounted on a post.
  • the slack limiter tab 20 is mounted in a tab enclosure 22 which includes three walls 24, 26, 28, and a cylindrical wall 30 which is attached directly to the wall 24, and indirectly to the wall 28 through a connecting wall 32.
  • the enclosure includes a corner 34 which receives one end of the slack limiter.
  • the reel wall 28 has an extended portion 50 which serves as a constraining wall and prevents flopover.
  • Figure 4 is a view of the base taken along the parting line of the base and the cover. At this location, the extended portion 50 is shown in cross section, corresponding to the base of Figure 7 described below. With the extended portion 50, when the tape
  • the slack limiter 20 operates similarly to the slack limiter in the cassette of Figure 1.
  • the slack limiter 20 is in a compression or leading edge mode.
  • the extended portion 50 of the reel wall 28 blocks the slack limiter, and prevents flopover.
  • the slack limiter 20 will not catch on the reel lock notches, will not cause motorboating, and will not create a cassette jam.
  • the reel wall extended portion can be formed completely as part of the base reel wall.
  • the reel wall extended portion 50 can be formed completely as part of the cover reel wall.
  • the reel wall extended portion 50 can be formed on part on the cover reel wall and in part on the base reel wall. It is also possible to use only one of the partial reel wall extended portions as this will sufficiently block the slack limiter.
  • the downwardly extending portion of the extended portion 50 is chamfered on the inner corner.
  • the chamfer 52 prevents damaging the slack limiter when the cover is assembled onto the base.
  • the downwardly extending portion shape, including the chamfered corner, provides more clearance with the slack limiter during assembly to prevent damaging the slack limiter.

Landscapes

  • Packaging Of Annular Or Rod-Shaped Articles, Wearing Apparel, Cassettes, Or The Like (AREA)

Abstract

Vidéocassette (10) comprenant une patte de régulation (20) de relâchement, prévue pour entrer en contact avec la bande (12) et empêcher cette dernière de se dérouler de la cassette (10), et des parois (24, 26, 28, 30, 32) servant à positionner ladite patte dans la cassette. Le boîtier de cette vidéocassette comprend deux parois (28) de bobine qui sont chacune situées à l'avant et définissent respectivement une zone de bobine, chaque patte (20) étant située adjacente à la paroi (28) de bobine respective. Chaque paroi (28) de bobine s'étend depuis la zone centrale jusqu'à la paroi latérale adjacente sur une distance telle qu'elle s'avance suffisamment vers l'avant pour empêcher la patte de régulation de relâchement de se plier au delà du galet (16) de guidage de la bande.
PCT/US1995/004015 1994-05-12 1995-03-31 Boitier de videocassette comportant une zone de regulation de relachement amelioree WO1995031810A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US24163994A 1994-05-12 1994-05-12
US08/241,639 1994-05-12

Publications (1)

Publication Number Publication Date
WO1995031810A1 true WO1995031810A1 (fr) 1995-11-23

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ID=22911544

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1995/004015 WO1995031810A1 (fr) 1994-05-12 1995-03-31 Boitier de videocassette comportant une zone de regulation de relachement amelioree

Country Status (1)

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WO (1) WO1995031810A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1011104A2 (fr) * 1998-12-08 2000-06-21 TDK Corporation Cassette à bande

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3142831A1 (de) * 1980-10-31 1982-06-16 Hitachi Maxell, Ltd., Ibaraki, Osaka Magnetbandkassette
DE3149441A1 (de) * 1980-12-18 1982-07-29 Fuji Photo Film Co., Ltd., Minami-Ashigara, Kanagawa Kassette fuer ein magnetisches aufzeichnungsband
US4544976A (en) * 1981-12-15 1985-10-01 Fuji Photo Film Co., Ltd. Pad provided in the interior of a videotape cassette
EP0289411A2 (fr) * 1987-04-24 1988-11-02 Sony Corporation Cassette pour bande magnétique et similaire comportant un dispositif de commande de tension de bande

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3142831A1 (de) * 1980-10-31 1982-06-16 Hitachi Maxell, Ltd., Ibaraki, Osaka Magnetbandkassette
DE3149441A1 (de) * 1980-12-18 1982-07-29 Fuji Photo Film Co., Ltd., Minami-Ashigara, Kanagawa Kassette fuer ein magnetisches aufzeichnungsband
US4544976A (en) * 1981-12-15 1985-10-01 Fuji Photo Film Co., Ltd. Pad provided in the interior of a videotape cassette
EP0289411A2 (fr) * 1987-04-24 1988-11-02 Sony Corporation Cassette pour bande magnétique et similaire comportant un dispositif de commande de tension de bande

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1011104A2 (fr) * 1998-12-08 2000-06-21 TDK Corporation Cassette à bande
EP1011104A3 (fr) * 1998-12-08 2000-07-19 TDK Corporation Cassette à bande
US6338449B1 (en) 1998-12-08 2002-01-15 Tdk Corporation Tape cassette capable of easily installing and securing biasing member for reel brake

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