Abstract:
The invention relates to a cassette for a tape type data recording medium, especially a reel cassette having screwed body halves, containing a clip with plastic tape guide rod, exerting constant maintaining forces on a tape guide rod and simultaneously on integral lugs, snapping into said cassette sidewall recesses and holding said two body halves in position.

Description:
DESCRIPTION  
         [0001]    The invention relates to a cartridge for data recording media in tape form, in particular a single-reel cartridge, according to the preamble of claim 1.  
           [0002]    As can be seen from FIGS.  1  to  3 , cartridges for data recording media in tape form, in particular single-reel cartridges, essentially comprise a housing, formed by a lower housing part ( 701 ) and an upper housing part ( 702 ) which are screwed to each other, a reel ( 30 ) which is mounted rotatably in said housing, has magnetic tape wound up on it (not represented) and the free end of which is connected to a tape guiding pin ( 50 ), the latter being fixed by means of a tape guiding pin clasp ( 40 ) in housing clearances ( 709 ,  710 ) of the lower cartridge part ( 701 ) and upper cartridge part ( 702 ) which are located in the region of the in tape exit opening, and the tape exit opening being located in a corner of the housing and capable of being closed by a spring-loaded sliding door ( 60 ).  
           [0003]    A cartridge of the generic type, or components of it, such as for example the spring-loaded sliding door of the tape exit opening, the reel brake and the tape guiding pin clasp, are, for example, the subject of the applications EP 0924 702 A1, EP 0926 675 A1 and EP 0926 675 A1.  
           [0004]    For satisfactory functioning of the tape guiding pin gripper on the equipment side, a closely toleranced retaining force is required for the tape guiding pin ( 50 ). Furthermore, the tape guiding pin ( 50 ) is to consist of non-magnetic and stainless metal. As a result of this requirement, the applicant regards the use of stainless steel to be unfavorable for the tape guiding pin clasp ( 40 ) and tape guiding pin ( 50 ). Use of the stainless steel/stainless steel material pairing is unfavorable to the extent that it has a tendency to “seize ” and consequently, during the course of use, the defined retaining force for the tape guiding pin ( 50 ) exceeds the permissible tolerance on account of changing frictional conditions. To be regarded as a further factor with adverse effects on the required constant retaining force are the production-related tolerances, which have a disproportionate effect in the case of tape guiding pin clasps of this size that are produced from spring steel wire or spring sheet metal.  
           [0005]    As already mentioned at the beginning, a cartridge with screwed housing halves is concerned here. This type of connection for the housing halves appears to the applicant to be favorable insofar as, in the case of repair, it offers the user an advantage with respect to access to the data stored in the cartridge that is not be underestimated. For example, if a cartridge with welded housing halves is damaged by the use of force so severely that it can no longer be loaded in the drive, the stored data are usually also lost, since prizing open the welded cartridge entails considerable risks for the data stored on the data medium in tape form contained in it. In contrast, a cartridge with a screwed housing can be opened without any problem, and the roll of tape with the stored data can easily be removed if need be and placed into an undamaged cartridge housing.  
           [0006]    However, set against this advantage is the not insignificant disadvantage that, in at least one region, the position of the screwed connection cannot be optimally chosen. For system-related reasons, no screwed connection can be provided within the region of the area (A) represented in FIG. 1 due to the gripper used for the tape guiding pin ( 50 ) and the required free running-out space for the data recording medium in tape form. This has the consequence that the screwed cartridge does not meet the requirements of a standardized drop test, in which the cartridge is subjected to a free drop from approximately 1 meter.  
           [0007]    As the tests conducted by the applicant show, the separating joint ( 720 ) between the lower housing part ( 701 ) and the upper housing part ( 702 ) of the cartridge side walls ( 711 ,  712 ) lying in the running-out direction of the tape tends to gape apart, with the housing halves changing their predetermined position in relation to each other, both horizontally and vertically, in this region, and consequently the tape guiding pin ( 50 ) can both assume a position deviating from its predetermined position of rest, or become jammed, and also spring out of its arrestment. The tape guiding pin ( 50 ) can in this case no longer be taken up by the gripper on the equipment side, of the tape guiding device, and the cartridge consequently cannot function.  
           [0008]    The prior art and these considerations therefore gave rise to the object of eliminating the disadvantages described of the inconstant retaining force on the cartridge side for the tape guiding pin ( 50 ) and its inadequate positional fixing under the stress occurring when the cartridge is dropped.  
           [0009]    The object was achieved by the cartridge of the type stated at the beginning being provided with a tape guiding pin clasp ( 40   a ,  40   b ,  40   c ,  40   d ) and by this clasp additionally having means which fixes the cartridge side walls ( 711 ,  712 ) of the housing lower part ( 701 ) and the housing upper part ( 702 ), lying in the running-out direction of the tape, in a positively engaging manner and with effect in the horizontal and vertical directions. 
       
    
    
       [0010]    The invention is now explained in more detail with reference to the drawings, in which specifically:  
         [0011]    [0011]FIG. 1 shows a schematic plan view of a housing lower part of a cartridge according to the prior art  
         [0012]    [0012]FIG. 2 shows a vertical section through the region of the tape exit opening of a cartridge according to the prior art  
         [0013]    [0013]FIG. 3 shows a side view in the direction of the tape exit opening of the region represented in FIG. 2  
         [0014]    [0014]FIG. 4 shows a perspective representation of a first embodiment of a tape guiding pin clasp according to the invention  
         [0015]    [0015]FIG. 5 shows a perspective representation of a second embodiment of a tape guiding pin clasp according to the invention  
         [0016]    [0016]FIG. 6 shows a perspective representation of a third embodiment of a tape guiding pin clasp according to the invention  
         [0017]    [0017]FIG. 7 shows a perspective representation of a fourth embodiment of a tape guiding pin clasp according to the invention  
         [0018]    [0018]FIG. 8 shows a partial plan view of the region of the tape exit opening of the first embodiment of a cartridge according to the invention  
         [0019]    [0019]FIG. 9 shows a vertical section through the region of the tape exit opening of the first embodiment of a cartridge according to the invention  
         [0020]    [0020]FIG. 10 shows a partial plan view of the region of the tape exit opening of the second embodiment of a cartridge according to the invention  
         [0021]    [0021]FIG. 11 shows a perspective representation of part of a cartridge according to the invention with a fitted tape guiding pin clasp according to embodiment 2. 
     
    
       [0022]    A first embodiment of the tape guiding pin clasp ( 40   a ) is now described with reference to FIG. 4, FIG. 8 and FIG. 9.  
         [0023]    As represented in FIG. 9, the positively engaging fixing, with effect in the horizontal and vertical directions, of the cartridge side walls ( 711 ,  712 ) lying in the running-out direction of the tape in relation to each other takes place by means of at least two clip connections ( 730 ) and with the clips ( 403   a ) that are integrated into the retaining plate ( 401   a ) of the tape guiding pin clasp ( 40   a ) being capable of engaging with corresponding clearances ( 713 ,  714 ) of the cartridge side walls ( 711 ,  712 ).  
         [0024]    As can be seen from FIG. 4, the tape guiding pin clasp ( 40   a ) is formed symmetrically with respect to the horizontal center line (H) and essentially comprises the retaining plate ( 401   a ), with the side of the retaining plate facing the reel ( 30 ) being preferably planar while the opposite side is beveled, starting from the horizontal center line (H), in the direction of the two end faces in a way corresponding to the contour of the receiving pockets ( 721 ,  722 ) located in the cartridge side walls ( 711 ,  712 ), and the spring elements ( 410   a ) formed on the end faces ( 404   a ) of the retaining plate ( 401   a ), essentially comprising an arcuate, offset fastening portion ( 411   a ) and the spring arm ( 412   a ), the respective free end of which is adjoined by the arresting portion ( 414   a ), with the contact surface ( 415   a ) of the latter with respect to the tape guiding pin ( 50 ) being of an at least partially cylindrical form and the spring element ( 410   a ) preferably having a rectangular cross section. Other cross-sectional shapes are likewise possible, it also being possible for the individual portions of the spring element ( 410   a ) to have different cross sections in a way corresponding to the materials selected for the tape guiding pin clasp ( 50 ). The outwardly facing planar surface ( 416   a ) of the arresting portion ( 414   a ) rises up in a step-shaped manner above the outwardly facing planar surface ( 413   a ) of the spring arm ( 412   a ) in order on the one hand to compensate for the production-related vertical tolerances, which have an effect during the assembly of the cartridge parts, and on the other hand to ensure that the retaining force for the tape guiding pin ( 50 ) is not adversely influenced by additional friction, based on undesirable contact of the spring arm ( 410   a ) with the corresponding housing surface, with the overall height (h) of the arresting portion ( 414   a ) corresponding to the height of the clamping portion ( 503 , depicted in FIG. 3) of the tape guiding pin ( 50 ).  
         [0025]    The retaining plate ( 401   a ) has symmetrically with respect to the horizontal center line (H) and with respect to the vertical center line (V) an essentially H-shaped clearance, with the free ends of the remaining central tabs ( 402   a ) being formed as clips ( 403   a ) which engage in corresponding clearances ( 713 ,  714 ) of the cartridge side walls ( 711 ,  712 ) when the tape guiding pin clasp ( 40   a ) is inserted into the cartridge housing. The H-shaped clearance and the thickness of the retaining plate ( 401   a ) are formed in such a way that, on the one hand, the resultant dimensions of the clips ( 403   a ) ensures a sufficiently stable clip connection ( 730 ) with the cartridge side walls ( 711 ,  712 ) and, on the other hand, no deforming of the retaining plate ( 401   a ) and the cartridge side walls ( 711 ,  712 ) occurs.  
         [0026]    The longitudinal sides of the retaining plate ( 401   a ) have tapering mounting bevels ( 418   a ,  419   a ) which run from the horizontal center line (H) in the direction of the end faces and are additionally formed as dovetails, so that, in interaction with the bevels ( 715 ,  716 ) provided in the cartridge side walls ( 711 ,  712 ), a dovetail guide is produced, through which the forces arising when the tape guiding pin ( 50 ) is moved in and out are introduced into the cartridge side walls ( 711 ,  712 ).  
         [0027]    A particularly preferred embodiment of the dovetail guide is obtained if the guiding surfaces formed by the bevels ( 418   a ) and facing in the direction of the fastening portion ( 411   a ) preferably provide support over their full surface area and the guiding surfaces formed by the bevels ( 419   a ) and facing in the direction of the arresting portion ( 414   a ) preferably provide only partial support. This is achieved for example by the mounting bevels ( 419   a ) facing in the direction of the arresting portion ( 414   a ) being partially set back, so that only supporting subsurfaces remain in a restricted region above and below the horizontal center line (H). This compensates for production-related tolerances and the tape guiding pin clasp ( 40   a ) can be mounted in the cartridge housing without any play or significant stress.  
         [0028]    As can also be seen from FIG. 8, the clearance ( 726   a ,  727   a ) provided in the lower cartridge part ( 701 ) and upper cartridge part ( 702 ), for receiving the spring arm ( 410   a ), is formed in such a way that said spring arm in the unloaded state, that is when the tape guiding pin ( 50 ) is in the position of rest in the cartridge housing or in the operating position outside the cartridge housing, bears against the projections ( 724   a ,  725   a ), with the projection ( 724   a ) being located in the lower housing part ( 701 ) and the projection ( 725   a ) being located in the upper housing part ( 702 ). This arrangement, together with the dimensions of the arresting portion ( 414   a ), achieves the effect that, after the tape guiding pin clasp ( 40   a ) has been fitted into the housing halves ( 701 ,  702 ), the spring arms ( 412   a ) are under slight prestress, but the tape guiding pin ( 50 ) does not induce any additional stress in the spring arms ( 412   a ) when it is in the position of rest in the cartridge housing. This means that the retaining forces only act on the spring arms ( 412   a ) during the operation of moving the tape guiding pin ( 50 ) in and out, and a more prolonged constancy of the retaining force is achieved as a result.  
         [0029]    A preferred second embodiment of the tape guiding pin clasp ( 40   b ) is now described with reference to FIG. 5, FIG. 10 and FIG. 11.  
         [0030]    As can be seen from FIG. 5, the further embodiment of the tape guiding pin clasp ( 40   b ) represented is likewise formed symmetrically with respect to the horizontal center line (H), with the retaining plate ( 401   b ) corresponding in all design details to the retaining plate ( 401   a ) of the first embodiment. This applies in particular to the preferred embodiment of the dovetail guide, here the guiding surfaces formed by the bevels ( 418   b ) and facing in the direction of the supporting portion ( 420   b ) providing support over their full surface area and the guiding surfaces formed by the bevels ( 419   b ) and facing in the direction of the arresting portion ( 414   b ) providing only partial support. The reference numbers equivalent to the first embodiment and not explained any further here are identified by an appended “b”, as used generally in the description of the second embodiment.  
         [0031]    The spring element ( 410   b ) itself is subdivided into the supporting arm ( 420   b ) and the spring arm ( 412   b ), with the spring arm ( 412   b ) again being adjoined by the arresting portion ( 414   b ), the contact surface ( 415   b ) of the latter with respect to the tape guiding pin ( 50 ) being of a convex form, and the spring element ( 410   b ) being articulated on the retaining plate ( 401   b ) between the supporting arm ( 420   b ) and the spring arm ( 412   b ) by means of the fastening portion ( 411   b ). The spring element preferably has a rectangular cross section. In the embodiment shown here, the fastening portion ( 411   b ) is located approximately at the center of the spring element ( 410   b ), but both the position of the fastening portion ( 411   b ) and the cross section of the spring arm ( 412   b ) can be varied in consideration of the respective conditions.  
         [0032]    As already described in the first embodiment, here, too, the outwardly facing planar surface ( 416   b ) of the arresting portion ( 414   b ) rises up in a step-shaped manner above the outwardly facing planar surfaces ( 413   b ) of the spring arm ( 412   b ), with a similar, step-shaped elevation ( 422   b ) being provided on the free end of the supporting arm ( 421   b ) in a way corresponding to the requirements of the spring element ( 410   b ), in order on the one hand to restrict the production-related vertical tolerances, which have an effect during the assembly of the cartridge parts, and on the other hand to ensure that the retaining force for the tape guiding pin ( 50 ) is not adversely influenced by additional friction, based on undesirable contact of the spring arm ( 410   b ) with the corresponding surface of the housing clearance ( 726   b ,  727   b ), with both the overall height (h) of the arresting portion ( 414   b ) and the overall height of the supporting arm ( 421   b ), including the stepped elevation ( 422   b ) provided at its free end, corresponding to the height of the clamping portion ( 503 ) of the tape guiding pin ( 50 ).  
         [0033]    As can also be seen from FIG. 10, the clearance ( 726   b ,  727   b ) provided in the lower cartridge part ( 701 ) and upper cartridge part ( 702 ), for receiving the spring arm ( 410   b ), is formed in such a way that said spring arm in the unloaded state, that is when the tape guiding pin ( 50 ) is in the position of rest in the cartridge housing or in the operating position outside the cartridge housing, bears against the projections ( 724   b ,  725   b ,  728   b ,  729   b ), with the projections ( 724   b ,  728   b ) being located in the lower housing part ( 701 ) and the projections ( 725   b ,  729   b ) being located in the upper housing part ( 702 ). This arrangement, together with the dimensions of the arresting portion ( 414   b ), achieves the effect that, after the tape guiding pin clasp ( 40   b ) has been fitted into the housing halves ( 701 ,  702 ), the spring arms ( 410   b ) are under slight prestress, but the tape guiding pin ( 50 ) does not induce any additional stress in the spring arms ( 412   b ) of the tape guiding pin clasp ( 40   b ) when it is in the position of rest in the cartridge housing. This again means that the retaining forces only act on the spring arms ( 412   b ) during the operation of moving the tape guiding pin ( 50 ) in and out, and a more prolonged constancy of the retaining force is achieved as a result.  
         [0034]    A further advantage of this described embodiment is consequently that the forces arising during the moving in and out of the tape guiding pin ( 50 ) are introduced into the bottom of the cartridge and the top of the cartridge via the resting surfaces of the projections ( 724   b ,  725   b ,  728   b ,  729   b ), and consequently do not act on the dovetail guide, and furthermore no relative movement between the supporting arm ( 420   b ), the lower part of the cartridge ( 701 ) and the upper part of the cartridge ( 702 ) is produced in the region of the bearing surfaces of the projections ( 724   b ,  725   b ,  728   b ,  729   b ), and consequently no quality-reducing abrasion occurs at this location.  
         [0035]    As already mentioned at the beginning, the tape guiding pin gripper/tape guide system, which guides the data medium in tape form to the take-up reel of the drive, imposes high requirements on the tape guiding pin clasp ( 40   a ,  40   b ,  40   c ,  40   d ). Of particular significance here are both the dimensional accuracy, while maintaining smallest possible production tolerances, and the material used. While the dimensional accuracy is ensured by using the precision injection-molding process, with respect to the selection of the material to be used it is necessary to ensure a high modulus of elasticity and adequate lubricity, to prevent inadmissible fluctuations in the retaining force due to diminishing of the resilient force and also due to changing frictional conditions in the region of the contact surfaces of the tape guiding pin and tape guiding pin clasp.  
         [0036]    High-grade moldable plastics are suitable as the material for the tape guiding pin clasp ( 40   a ,  40   b ,  40   c ,  40   d ), high-grade being understood to mean plastics with a high modulus of elasticity and good wear resistance. Thermoplastics, elastomers and thermosetting plastics are suitable as base materials. Examples of preferred materials which can be used are polycarbonate (PC), polyamide (PA) and polyoxymethylene (POM), it also being possible for the base materials to be provided with fillers or functional additives. Both organic and inorganic substances are suitable as fillers, taking the form of particles, for example as fibers or spheres.  
         [0037]    Carbon-fiber-reinforced polyoxymethylene is particularly preferred, the lubricity being ensured by the addition of polytetrafluoroethylene. A material which meets these requirements is obtainable for example under the designation KCL-4022D from the company LNP Engineering Plastics Inc. This material is based on polyoxymethylene, contains 10% carbon fiber and 10% polytetrafluoroethylene and has a modulus of elasticity of 7 300 Mpa. To obtain both a reliably acting clip connection ( 730 ) and a functionally capable dovetail guide, the wall thickness of the cartridge side walls ( 711 ,  712 ), lying in the running-out direction of the tape, of the lower housing part ( 701 ) and the housing upper part ( 702 ) is preferably to be increased in the corresponding region, in particular in the region of the bevels ( 715 ,  717  in the lower housing part) and ( 716 ,  718  in the upper housing part—not represented) to the extent permitted by the run-out of the tape.  
         [0038]    As FIG. 9 also reveals, for simple release of the clip connection ( 730 ) it is expedient to provide in the cartridge side walls ( 711 ,  712 ), in the region of the clip connections ( 730 ), a respective bore ( 733 ), through which the clip ( 403   a ,  403   b ) is pressed by means of a suitable pin (not represented) out of the corresponding clearance ( 713 ,  714 ) of the cartridge side wall ( 711 ,  712 ).  
         [0039]    The third tape guiding pin clasp ( 40   c ), represented in FIG. 6, represents an embodiment of the tape guiding pin clasp ( 40   b ) depicted in FIG. 5 that has been optimized from technical injection-molding aspects, the retaining plate ( 401   c ) now having only a slot-shaped clearance ( 409   c ) instead of the H-shaped clearance. The reference numbers equivalent to the second embodiment and not explained any further here are identified by an appended “c”.  
         [0040]    Finally, represented in FIG. 7 is a further material-optimized variant of the tape guiding pin clasp ( 40   d ), with the retaining plate now only comprising a cross-piece ( 401   d ) which connects the two spring arms ( 410   d ) to each other. Provided on the cross-piece, are, both the two clips ( 403   d ) for connecting the upper housing part ( 701 ) and the lower housing part ( 702 ) and the two butt straps ( 417   d ) for fixing the tape guiding pin clasp ( 40   d ) in the housing halves.  
         [0041]    Use of the tape guiding pin clasps according to the invention that are represented is not restricted to, screwed cartridge housing they can also be used advantageously in the case of cartridge housing halves that are welded to each other.