Abstract:
A pole base assembly for a magnetic recording/reproducing apparatus for guiding a tape drawn from a reel through a predetermined path in parallel or substantially in parallel toward a lead surface of a head drum. The pole base assembly comprises a pole base disposed to approach and retreat from a side of the head drum when the tape is loaded and unloaded, respectively, a sloping pole disposed to be sloped on the pole base, to be parallel or substantially parallel to the lead surface of the head drum, for guiding the tape fed to the head drum at a predetermined angle, to be parallel to the lead surface, and a supporting holder disposed on the pole base, and having a sloping part to support the sloping pole to be inclined at a predetermined angle.

Description:
This application claims benefit under 35 U.S.C. § 119 from Korean Patent Application No. 2002-52623, filed on Sep. 2, 2002, the entire content of which is incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a magnetic recording/reproducing apparatus, and more particularly, to a pole-base assembly for a magnetic recording/reproducing apparatus, for guiding a tape which is released from a tape cassette and loaded in contact with a head drum. 
   2. Description of the Related Art 
   Generally, a magnetic recording/reproducing apparatus is a device for recording information on a recording medium such as a magnetic tape, and reproducing the recorded information. There are several types of magnetic recording/reproducing apparatus, namely, a VCR (Video Cassette tape Recorder), a camcorder, and so on. 
   A magnetic recording/reproducing apparatus typically comprises a main deck at which a head drum is rotatably disposed, a main sliding member movably disposed to slide laterally on the main deck, a sub-deck movably disposed to slide longitudinally on the main deck, a moving means for moving a cassette tape inserted into the sub-deck to a predetermined position in the main deck, and a reel table for receiving two tape reels of the cassette tape and driven to wind one tape reel. The head drum is rotatably disposed at the main deck to record/reproduce information on a tape. The apparatus further comprises a tape loading means for loading the tape on the head drum, and a tape guide device. 
     FIG. 1  shows an example of a tape guide device. The tape guide device comprises an entrance pole base assembly  20  and an exit pole base assembly  30  for guiding the tape T at both sides of the head drum  10  to drive around the head drum  10 , and a plurality of guideposts  41 ,  42 ,  43 ,  44 . The guideposts  41  and  42  are fixed to the main deck  1 , and the other guideposts  43  and  44  are moved in the main deck  1  to guide the driving of the tape T and to adjust tension. 
   The pole-base assemblies  20 ,  30  are moved along a direction A by a predetermined moving means to guide the driving of the tape T. Since the head drum  10  is disposed at a predetermined slope at the main deck  1 , the pole-base assemblies  20 ,  30  have special construction for guiding the tape T inclined at a predetermined angle as the tape T is being guided along the head drum  10 . 
   Namely, the entrance pole base assembly  20  comprises a pole base  21 , a rotation supporting roller  23  and a sloping pole  25 , as shown in  FIG. 2 . Since the head drum is disposed to be sloped, the sloping pole  25  is disposed to be sloped with respect to the rotation supporting roller  23  between the rotation supporting roller  23  and head drum  10  to maintain parallel to the tape T. 
   With the conventional pole base assembly having the above construction, when the pole base  21  is manufactured by a molding process, a hole for coupling with the sloping pole  25  is bored and then the pole base  21  is press-fit into the hole to be fixedly disposed at a predetermined angle. In this case, the angle of the sloping pole  25  press-fit in the hole is determined by the initial position of the manufactured hole. Therefore, the angle of the sloping pole press-fit in the hole varies according to a manufacturing tolerance of the hole, thereby increasing the likelihood that the sloping pole will be sloped at an incorrect angle, and thus decreasing productivity. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is to provide an improved pole base assembly for a magnetic recording/reproducing apparatus. 
   Another object of the present invention is to provide a pole base assembly having a pole base which supports a sloped pole in an improved manner. 
   These and other objects are substantially achieved by providing an improved pole base assembly for a magnetic recording/reproducing apparatus for guiding a tape drawn from a reel through a predetermined path toward a lead surface of a head drum. The pole base assembly comprises a pole base disposed to approach and retreat from a side of the head drum when the tape is loaded and unloaded, respectively, a sloping pole, coupled to the pole base and sloped at a sloping angle with respect to the pole base, for guiding the tape fed to the head drum at a predetermined angle, to be substantially parallel to the lead surface, and a supporting holder, disposed on the pole base and configured to support the sloping pole at the sloping angle. The supporting holder comprises a first supporting wall that has a sloping surface for supporting the sloping pole at the sloping angle, and a second supporting wall that has a supporting surface in contact with the supporting wall for supporting the sloping pole. 
   The first supporting wall has a gradually increasing thickness from an upper end to a lower end. The sloping surface has a width that is greater than the radius of the sloping pole and smaller than the diameter of the sloping pole, and more particularly, the sloping surface has a width that is substantially uniform along the length of the sloping surface. The supporting surface is formed at substantially 90° with respect to the sloping surface, and has a substantially uniform width that is greater than the radius of the sloping pole and smaller than the diameter of the sloping pole. 
   Furthermore, the second supporting wall has a sub-sloping surface which is in substantially parallel relation with respect to the sloping surface. The supporting holder further includes a bottom surface which is adapted to contact and support a lower end of the sloping pole, and extends at substantially 90° with respect to the sloping surface. 
   The pole base further has a supporting hole therein and a supporting boss spaced from the supporting hole, such that a first axis X extends from the center of the supporting hole to the center of the supporting boss, a second axis Y extends in line with the center of the supporting hole, and a third axis Z extends in a perpendicular relation with respect to the first axis X and the second axis Y. The sloping pole is located at a direction angle θ with respect to the first axis X. The sloping pole is disposed on the pole base to have a predetermined slope α with respect to another imaginary axis Y′ which is in parallel with the second axis Y. In addition, the sloping pole can be bonded to the pole base with adhesive, or can be formed integral with the pole base. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be described in detail with reference to the following drawings in which like reference numerals refer to like elements wherein: 
       FIG. 1  is a schematic plane view for illustrating a conventional magnetic recording/reproducing apparatus; 
       FIG. 2  is a partial perspective view showing important parts of  FIG. 1 ; 
       FIG. 3  is a perspective view showing a pole base assembly for a magnetic recording/reproducing apparatus in accordance with an embodiment of the invention; 
       FIG. 4  is a cross-sectional view along a line I—I in  FIG. 3 ; 
       FIG. 5  is a front view of the pole base assembly of  FIG. 3 ; 
       FIG. 6  is a plan view of the pole base assembly of  FIG. 3 ; 
       FIG. 7  is a sectional view taken on line II—II of  FIG. 6 ; and 
       FIG. 8  is a plane view showing the pole base assembly of  FIG. 3  from another angle. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Certain embodiments of the invention will be hereinafter described in detail with reference to the accompanying drawings. 
   Referring to  FIGS. 3 and 4 , a pole base assembly for a magnetic recording/reproducing apparatus in accordance with an embodiment of the invention comprises a pole base  50 , a sloping pole  60  disposed to be inclined at a predetermined angle on the pole base  50 , and a supporting holder  70  disposed on the pole base  50  for supporting the sloping pole  60  at the predetermined slope. 
   In loading and unloading of the tape cassette, the pole base  50  advances and retreats in the transverse direction of the head drum along a guide rail that is provided on the deck. To this end, as shown in  FIG. 5 , the pole base  50  includes a guide protrusion  51  guided along the guide rail during the loading/unloading of the pole base  50  and a supporting boss  52  to which a link unit (not shown) is connected for loading/unloading of the pole base  50 . Both the guide protrusion  51  and the supporting boss  52  protrude from the lower surface of the pole base  50 , and are spaced apart from each other by a predetermined distance. The loading/unloading of the pole base  50  having the above-described construction is generally known in the art, and accordingly, further description thereof will be omitted. 
   Further provided on the pole base  50  are a sloping pole  60  and a vertical pole  63  for guiding the tape at a predetermined posture. The vertical pole  63  is connected to a supporting hole  50   a  formed in the pole base  50 , and assembled in a perpendicular or substantially perpendicular relation with respect to the upper surface of the pole base  50 . The supporting hole  50   a  is formed through the center of the guide protrusion  51 . The vertical pole  63  may be connected in the supporting hole  50   a  by a screw or press-fitting. The vertical pole  63  guides the running of the magnetic tape toward the head drum in advance of the guidance of the sloping pole  60 . 
   The sloping pole  60  is disposed on the pole base  50  at a predetermined slope. As shown in  FIG. 2 , because the head drum  10  is in an inclined position at a predetermined angle, the sloping pole  60  is accordingly inclined so as to guide the tape in parallel or substantially parallel relation with respect to the lead surface of the head drum  10 . 
   The supporting holder  70  is provided on the pole base  50  to support the pole base  50  at a predetermined slope. The supporting holder  70  includes a first supporting wall  71  that has a sloping surface  71  a for supporting the sloping pole  60  at a predetermined angle, and a second supporting wall  73  that has a supporting surface  73   a  in contact with the supporting wall  71  and for supporting the sloping pole  60 . 
   Referring now to  FIGS. 5 and 6 , the structure and position of the supporting holder  70  and the sloping pole  60  will be described with reference to a 3-dimensional coordinate system based on a first axis X extending from the center of the supporting hole  50   a  to the center of the supporting boss  52 , a second axis Y extending in line with the center of the supporting hole  50   a , and a third axis Z extending in a perpendicular relation with respect to the first and the second axes X, Y. 
   In the 3-dimensional coordinate system, the sloping pole  60  is located at a direction angle θ with respect to the first axis X. Also, the sloping pole  60  is disposed on the pole base  50  to have a predetermined slope α with respect to another imaginary axis Y′ which is in parallel with the second axis Y. To this end, the sloping surface  71   a  of the supporting holder  70  is located at the direction angle θ, but at the slope as much as α. The direction angle θ and the slope α may vary in accordance with the slope of the head drum as employed, and thus, they are not strictly limited to certain fixed values. 
   Meanwhile, for the sake of increasing the supporting force of the sloping pole  60 , the first supporting wall  71  that has the sloping surface  71   a  is formed such that the same has a gradually increasing thickness from the upper end to the lower end. Also, the sloping surface  71   a  has a width w 1  that is greater than the radius r, but smaller than the diameter R of the sloping pole  60 . Accordingly, the sloping pole  60  is stably supported in contact with the sloping surface  71   a . The sloping surface  71   a  has the uniform or substantially uniform width w 1  along the length thereof, that is, in the direction parallel or substantially parallel with the sloping pole  60 . 
   The sloping surface  71   a  is formed such that it is in perpendicular relation with respect to a plane connecting the second axis Y and a certain axis x′ moved from the first axis X by the direction angle θ. 
   The second supporting wall  73  has a supporting surface  73   a  for contact-supporting the sloping pole  60  just as the sloping surface  71   a  of the first supporting wall  71  does. The supporting surface  73   a  also has a ‘V’ shape, which is also the same for the supporting surface  71   a . For a more stable support of the sloping pole  60 , the supporting surface  73   a  is formed at 90° or substantially 90° with respect to the sloping surface  71   a . Accordingly, the supporting surface  71   a  crosses the plane of the first and the third axes X, Z in a perpendicular relation. Just like the sloping surface  71   a  of the first supporting wall  71 , the supporting surface  73   a  has a width w 2  that is greater than the radius r, but smaller than the diameter R of the sloping pole  60 . The supporting surface  73   a  also has the uniform width w 2  in the parallel direction with respect to the sloping pole  60 . 
   The second supporting wall  73  has a sub-sloping surface  73   b  which is in parallel or substantially parallel relation with respect to the sloping surface  71   a . As the width w 2  of the supporting surface  71   a  of the sub-sloping surface  73   b  is uniform, the sloping pole  60  is provided at the slope as much as α. By providing the sub-sloping surface  73   b , interference of the tape in the supporting holder  70  can be avoided while the tape is guided by the sloping pole  60  supported on the supporting holder  70 . The second supporting wall  73  has a predetermined thickness, that is, a predetermined length between the supporting surface  73   a  and the outer surface  73   c  opposite to the supporting surface  73   a.    
   Because the sloping pole  60  is supported on two points, that is, on the sloping surface  71   a  and the supporting surface  73   a , the position and posture thereof are determined automatically. The supporting holder  70  further includes a bottom surface  75  to contact-support the lower end of the sloping pole  60 . The bottom surface  75  corresponds to the upper surface of the pole base  50 , and is provided at a predetermined angle, and preferably at 90°, with respect to the sloping surface  71   a . Accordingly, the sloping pole  60  is fixed in position by the close contact with the sloping surface  71   a , the bottom surface  75  and the supporting surface  73   a . The sloping pole  60  is secured onto the supporting holder  70  by adhesive, such as a bond. Preferably, adhesive is first applied to the sloping surface  71   a , the supporting surface  73   a  and the bottom surface  75 , and then the sloping pole  60  is positioned thereon. 
   It is also preferable to form the supporting holder  70  at a lower height than the sloping pole  60  in an inclined state so that there is no interference. However, the supporting holder  70 , that is, the sloping surface  71   a  may preferably have a length more than a half of the length of the sloping pole  60  so as to secure stable supporting force of the sloping pole  60 . 
   The supporting holder  70  constructed as above may preferably be formed integrally with the pole base  50 . This is because, by integrally forming the supporting holder  70  with the pole base  50  through a metal mold or an injection molding, allowances between the sloping surface  71   a , the supporting surface  73   a  and the bottom surface  75  can be maximized. 
   With the pole base assembly of the tape recorder according to the embodiment of the present invention described above, the sloping pole  60  is supported at a predetermined slope by forming the supporting holder  70  integrally with the pole base  50 . Because the position and the posture of the sloping pole  60  are determined by the sloping surface  71   a , the supporting surface  73   a  and the bottom surface  75 , assembly can be easily completed without having to use a separate jig or inspection equipment, but simply by bonding the sloping pole  60  onto the supporting holder  70 . 
   Because the sloping pole  60  can be assembled onto the pole base  50  in a desired position and posture, productivity increases, while the defect rate decreases. 
   Further, by designing the sloping surface  71   a , the supporting surface  73   a  and the bottom surface  75  of the supporting holder  70  based on the 3-dimensional coordinate system that uses the supporting hole  50   a  and the supporting boss  52  provided to the pole base  50 , appropriate design in respect to sizes and dimensions of each part is enabled, and alteration in design becomes easier. 
   With the pole base assembly of the magnetic recording/reproducing apparatus according to the embodiments of the present invention described above, while the sloping pole is assembled on the sloping surface which is provided on the pole base in advance, the inclination of the sloping pole is automatically determined by the sloping surface. As a result, defect rate decreases and productivity increases. 
   Although certain embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions can be made without departing from the scope and spirit of the invention as disclosed in the accompanying claims.