Abstract:
A capstan shaft cleaning device has a cleaning member removing dirt attached to a capstan shaft and a moving mechanism moving the cleaning member between a position at which the cleaning member contacts the capstan shaft and a position at which the cleaning member is separated from the capstan shaft, the cleaning member having at least two points of contact contacting a periphery of the capstan shaft.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a capstan shaft cleaning device. 
     2. Description of the Related Art 
     Generally, an apparatus for magnetically recording and reproducing information such as, for example, a digital audio tape recorder, or DAT, is provided with a capstan shaft and pinch roller for making a magnetic recording medium such as a magnetic tape run at a constant speed. The capstan shaft is rotated at a constant rpm by a capstan motor, the pinch roller presses the magnetic tape against the capstan shaft during a tape loading operation and the tape runs at a constant speed corresponding to the rotation of the capstan shaft, making it possible to carry out stable magnetic recording and reproduction of information to and from the magnetic tape. 
     As described above, the capstan shaft is in sliding contact with the magnetic tape during magnetic recording and reproduction, so magnetic particles can come loose from and fall off the magnetic tape onto the capstan shaft. Once these magnetic particles fall onto the capstan shaft the magnetic tape can no longer run with stability. 
     As a result, the conventional magnetic recording/reproduction apparatus is provided with a cleaning device to remove magnetic particles and other such dirt and dust from the capstan shaft. 
     FIG. 1 is a partial cutaway plan view of a conventional capstan shaft cleaning device. As shown in the diagram, the capstan shaft  2  is supported so as to rotate freely within a capstan housing  3 . 
     A felt material  4  that functions as a cleaning device  1  is affixed to the capstan housing  3 . The felt material  4  is positioned so as to contact the capstan shaft  2  from a side opposite the side on which the magnetic tape slidingly contacts the capstan shaft  2 . Accordingly, the felt material  4  is in continuous contact with the capstan shaft  2 , wiping away magnetic particles and other dirt. 
     However, a problem arises in that although the conventional cleaning device  1  using a felt material  4  performs adequately at first, over time the felt material  4  becomes dirty and its effectiveness as a cleaner diminishes sharply. In the worst case, magnetic particles adhering to the felt material  4  come off onto the capstan shaft  2 . 
     Additionally, because the felt material  4  is affixed to the capstan housing  3  it is not easy to replace the felt material  4  when the felt material  4  becomes dirty. Moreover, because the felt material  4  is used under high-temperature conditions the felt material  4  sometimes peels off from the capstan housing  3 . 
     SUMMARY OF THE INVENTION 
     Accordingly, it is a general object of the present invention to provide an improved and useful capstan shaft cleaning device in which the disadvantages described above are eliminated. 
     A further object of the present invention is to provide an improved and useful capstan shaft cleaning device in which the cleaning effectiveness thereof can be maintained for an extended period of time. 
     The above-described objects of the present invention are achieved by a capstan shaft cleaning device comprising: 
     a cleaning member removing dirt attached to a capstan shaft; and 
     a moving mechanism moving the cleaning member between a position at which the cleaning member contacts the capstan shaft and a position at which the cleaning member is separated from the capstan shaft, 
     the cleaning member having at least two points of contact contacting a periphery of the capstan shaft. 
     According to the invention described above, the effectiveness of the capstan shaft cleaning device can be maintained over an extended period of time. In particular, because cleaning member contact points are formed at at least two points along a peripheral direction of the capstan shaft, the capstan shaft cleaning device can still securely slidably contact the capstan shaft and remove magnetic particles and other dirt adhering to the capstan shaft even if the assembled capstan shaft cleaning device and the capstan shaft are out slightly of position with respect to each other. 
     Additionally, the above-described objects of the present invention are also achieved by the capstan shaft cleaning device as described above, wherein: 
     the contact points of the cleaning member are made of a hard resin material including an antistatic agent; and 
     the contact points form projections with obtuse angles in cross-section in a direction of a radius of the capstan shaft. 
     According to the invention described above, there is no diminution in cleaning power as is the case with the conventional felt material and cleaning effectiveness can be maintained over an extended period of time. 
     Additionally, the above-described objects of the present invention are also achieved by a capstan shaft cleaning device comprising: 
     a cleaning member removing dirt attached to a capstan shaft; and 
     a moving mechanism moving the cleaning member between a position at which the cleaning member contacts the capstan shaft and a position at which the cleaning member is separated from the capstan shaft, 
     the moving mechanism being provided with a follow mechanism that displaces so that a contact line of the cleaning member contacting the capstan shaft adheres closely to the capstan shaft. 
     Additionally, the above-described objects of the present invention are also achieved by a capstan shaft cleaning device as described above, wherein the cleaning member comprises: 
     an arm; and 
     a bearing part, 
     a contact portion having a contact line parallel to an axis of the capstan shaft provided at one end of the arm, the bearing part extending cylindrically from an intermediate position of the arm in a direction parallel to the axis of the capstan shaft, the bearing part supported by a shaft, a gap being provided between the shaft and a portion of the bearing part parallel to a surface including the two contact lines of the cleaning member, a projection being formed at a portion of the bearing part near a side on which the arm is provided, the bearing part being engaged by the shaft via the projection as to be displaceable about the projection, the contact line of the cleaning member following and adhering closely to the capstan shaft. 
     According to the invention described above, the contact line of the cleaning member changes so as to follow and closely adhere to the capstan shaft and ensure removal of magnetic particles and other dirt adhering to the capstan shaft. 
     Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial cutaway plan view of a conventional capstan shaft cleaning device; 
     FIG. 2 is a plan view of a magnetic recording/reproduction device adapting a capstan shaft cleaning device according to an embodiment of the present invention; 
     FIG. 3 is an oblique view of a capstan shaft cleaning device according to an embodiment of the present invention; 
     FIG. 4 is a simplified plan oblique view of a capstan shaft cleaning device according to an embodiment of the present invention; and 
     FIGS. 5A and 5B are a partial cross-sectional view of the cleaning device shown in FIG. 4 along line A—A and a partial cross-sectional view of the cleaning device shown in FIG. 4 along line B—B, respectively. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A description will now be given of one preferred embodiment of a magnetic head according to the present invention, with reference to the accompanying drawings. 
     For clarity of explanation, a brief description will first be given of a magnetic recording/reproduction apparatus such as a DAT streamer, hereinafter referred to simply as an apparatus, adapting the cleaning device  28  of the present invention. 
     In the apparatus  10  shown in FIG. 2, magnetic tape  14  is extracted from a loaded DAT tape cassette  12  by loading poles  16 ,  18  and wound around a rotary drum  20  having a rotary head not shown in the diagram. The magnetic tape  14  is urged onward by a pinch roller  22  and a capstan shaft (capstan)  24 , with the rotary drum (rotary head)  20  rotating at high speed in a direction indicated in the diagram by arrow X. Information is recorded to the magnetic tape  14  by the rotary head and information recorded on the magnetic tape  14  is reproduced by the rotary head. The rotary drum  20  is mounted on a drum base fixedly mounted on a chassis not shown in the diagram. Additionally, the pinch roller  22  and capstan shaft  24  is provided on a sub-chassis  26 , the sub-chassis  26  being fixedly mounted on the chassis. It should be noted that the capstan shaft cleaning device  28  according to the present invention is mounted on the sub-chassis  26  and disposed opposite the pinch roller  22 , with the capstan shaft  24  in between the capstan shaft cleaning device  28  and the pinch roller  22 . 
     Next, a description will be given of the composition of the capstan shaft cleaning device  28 . 
     As shown in FIGS. 3,  4 ,  5 A and  5 B, the capstan shaft cleaning device  28  chiefly comprises a cleaning member  30  and a movement member  32  for moving the cleaning ember  30 . 
     The cleaning member  30  comprises an arm  31  and a bearing part  40 . Contact points  38   a,    38   b  are formed at one end of the cleaning member  30 , the contact points  38   a,    38   b  extending along lines of contact LI, L 2  with the capstan shaft  24  parallel to the axis of the capstan shaft  24 . The bearing part  40  extends vertically from an intermediate portion of the arm  31 , along a line parallel to the axis of the capstan shaft  24 . The bearing part  40  is supported by a shaft  36  fixedly mounted on the subchassis  26 . 
     The contact points  38   a,    38   b  are made of a hard resin material including an antistatic agent. As described above there are two such contact points  38   a,    38   b,  so even if there is a slight misalignment between the relative positions of the capstan shaft cleaning device  28  and the capstan shaft  24  the capstan shaft cleaning device  28  can still be in secure sliding contact with the capstan shaft and remove magnetic particles and other dirt adhering to the capstan shaft. Additionally, there is no transfer of static electricity from the cleaning member  30  to the capstan shaft  24 , so the magnetic tape  14  can be prevented from winding around the capstan shaft  24 . 
     It should be noted that ceramics and industrial gemstones are also possible materials for the cleaning member  30 . 
     As shown in FIG. 4, the contact points  38   a,    38   b  in cross-section in a direction of a radius of the capstan shaft  24  form projections with obtuse angles θa, θb. It should be noted that the contact points  38   a,    38   b  may in cross-section also form three or more acute angle projections, although two projections are functionally sufficient. Additionally, considering the increased wear on the contact points  38   a,    38   b  in the event that the contact points  38   a,    38   b  in cross-section form acute angles, it is preferable that the contact points  38   a,    38   b  form obtuse angle projections. By so doing the cleaning capacity of the cleaning member  30  is not attrited and magnetic particles adhering to the capstan shaft  24  can be securely removed. 
     Additionally, a through-hole aperture portion is formed on the bearing part  40  as shown in FIG. 4, in such a way that a radius thereof in a direction of axis b is greater than a radius thereof in a direction of axis a. Accordingly, a gap  42  is formed between portions  40   a,    40   b  of the bearing part  40  parallel to a surface that includes the two lines of contact L 1 , L 2  with the capstan shaft  24  of the contact points  38   a,    38   b  one the one hand and the shaft  36  described above on the other. 
     Additionally, as shown for example in FIG. 5B, projections  44   a,    44   b  are formed at portions  40   a,    40   b  of the bearing part  40  near a side on which the arm  31  is provided. Portions  40   a,    40   b  of the bearing part  40  at which the projections  44   a,    44   b  are formed correspond to a central position of each of the lines of contact L 1 , L 2  of the cleaning member  30  described above. It should be noted that the gap  42  between the bearing part  40  and the axis  36  is such as to be smaller on a side on which the arm  31  is provided than on a side opposite the side on which the arm  31  is provided, as shown in FIG.  5 B. Accordingly, the bearing part  40  is engaged by the shaft  36  via the projections  44   a ,  44   b  so as to swingingly displace through an arc of approximately 1° in a direction indicated in FIG. 5B by arrow Y, being self-aligning. 
     The capstan shaft cleaning device  28  having the structure described above is in a standby mode when the apparatus  10  is not operating or when the magnetic tape  14  is urged forward by the pinch roller  22  and the capstan  24 . That is, the capstan shaft cleaning-device  28  is in a state in which the capstan shaft cleaning device  28  is separated from the capstan shaft  24 . In the time it takes for the capstan shaft  24  to stop rotating after the pinch roller  22  separates from the capstan shaft  24  when the apparatus  10  stops, the contact points  38   a,    38   b  of the capstan shaft cleaning device  28  are urged by the moving mechanism  32  comprising a crank mechanism or the like into contact with the capstan shaft  24  from a side of the capstan shaft  24  opposite the side of the capstan shaft  24  pressed by the pinch roller  22 , thus wiping the capstan shaft  24  free of magnetic particles and other dirt adhering to the capstan shaft  24  and thereby cleaning the capstan shaft  24 . 
     Accordingly, the contact points  38   a,    38   b  are in contact with the capstan shaft  24  not continuously but for a predetermined time period only, so the contact points  38   a,    38   b  are not subjected to unnecessary wear. Additionally, the capstan shaft cleaning device  28  can still securely slidably contact the capstan shaft  24  and remove magnetic particles and other dirt adhering to the capstan shaft  24  even if the assembled capstan shaft cleaning device  28  and the capstan shaft  24  are out of position with respect to each other, because cleaning member contact points are formed at at least two points along a peripheral direction of the capstan shaft and thus the contact lines L 1 , L 2  formed by the contact points  38   a,    38   b  of the cleaning member  30  displace as the bearing part of the capstan shaft cleaning device  28  displaces, thus following and closely contacting the capstan shaft  24  so as to securely slide along the capstan shaft  24  and wiping the capstan shaft  24  free of magnetic particles and the like adhering to the capstan shaft  24 . 
     It should be noted that that although the embodiment described above uses a DAT streamer as the device in which the capstan shaft cleaning device of the present invention is adapted, the cleaning device of the present invention can be adapted for use with a wide variety of magnetic recording/reproduction apparatuses having a capstan shaft. 
     The above description is provided in order to enable any person skilled in the art to make and use the invention and sets forth the best mode contemplated by the inventors of carrying out the invention. 
     The present invention is not limited to the specifically disclosed embodiments and variations, and modifications may be made without departing from the scope and spirit of the present invention. 
     The present application is based on Japanese Priority Application No. 11-069058, filed on Mar. 15, 1999, the entire contents of which are hereby incorporated by reference.