Abstract:
A magnetic recording/reproduction apparatus for magnetically recording information to and/or reproducing information from a recording medium, the magnetic recording/reproduction apparatus having an electrically grounded tape cassette loading/ejecting mechanism, the tape cassette loading/ejecting mechanism including a chassis adapted to be electrically grounded, a cassette holder for loading a tape cassette into and/or ejecting a tape cassette from the apparatus, a slider cam assembly mounted on the chassis and mechanically coupled to the cassette holder for moving the cassette holder to and from a predetermined loading position inside the apparatus, and a static electric charge removal mechanism electrically connected to the cassette holder for removing a static electric charge from the cassette holder.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to an apparatus for magnetically recording information to and/or reproducing information from a recording medium, and more particularly, to a Digital Audio Tape Recorder, or DAT. 
     2. Description of the Related Art 
     One type of apparatus for magnetically recording information to and/or reproducing information from a recording medium, such apparatus hereinafter referred to as a magnetic recording/reproduction apparatus, is a Digital Audio Tape recorder, or DAT. 
     A conventional DAT  1  is shown in FIG.  1 . As shown in the drawing, the DAT  1  mainly comprises a chassis  2 , on top of which are provided a variety of mechanisms and components, including a tape cassette loading and ejecting mechanism  3 , a reel drive mechanism  4 , a rotary cylinder  5  and a tape loading mechanism  6 . 
     The tape cassette loading and ejecting mechanism  3 , hereinafter referred to as simply the tape cassette loading mechanism  3 , loads a tape cassette (not shown in the diagrams) to a predetermined position within the DAT  1 . The tape cassette loading and ejecting mechanism  3  mainly comprises a cassette holder  7  into which the tape cassette is loaded, a slider cam assembly  8  capable of sliding in the X 1 -X 2  direction as indicated in the diagram, and a drive mechanism which, however, is not shown in the diagram. It should be noted that the cassette holder  7 , the chassis  2  and the slider cam assembly  8  are made of metal. 
     The cassette holder  7  and the slider cam assembly  8  are connected by a metal shaft  9  such that as the slider cam assembly  8  moves the cassette holder  7  moves with it. 
     The movement of the cassette holder  7  is determined by a cam groove  11   a  of a cam  11  formed on the slider cam assembly  8  together with a substantially L-shaped guide groove  13  formed in a resinous side wall of the chassis. In other words, the drive mechanism causes the slider cam assembly  8  to move in the X 1  direction as shown in FIG. 1, which causes the cassette holder  7  to first move horizontally in the X 1  direction and then drop downward. By so doing, a tape cassette loaded in the cassette holder  7  is transported to the above-described predetermined position within the apparatus  1  for recording/reproduction. It should be noted that the cam  11  is made of a resinous material to facilitate the sliding of the shaft  9  along the cam  11 . 
     The reel drive mechanism  4  rotatably drives a supply reel and a take-up reel, neither of which is shown in the drawing. Additionally, the magnetic tape (not shown) extracted from the tape cassette is wound around the rotary cylinder  5  at a predetermined angle, with magnetic recording of information to and reproduction of information from the magnetic tape performed as the tape moves. It should be noted that the rotary cylinder  5  is mounted atop a resinous drum base  14 . Additionally, the tape loading mechanism  6  extracts the magnetic tape from the tape cassette and winds the magnetic tape around the rotary cylinder  5  at a predetermined angle. 
     The mode switching mechanism  10  comprises a mode switching gear, a link and a mode switching plate, none of which is shown in the drawing. The mode switching gear is rotatably driven by a mode switching motor  15 . It should be noted that reference number  19  in FIG. 1 indicates a motor bracket. Additionally, a circuit board  16  that controls the mode switching motor  15  is provided adjacent to the mode switching motor  15 . Additionally, the tape cassette loading mechanism  3  and the tape loading mechanism  6  are connected to the mode switching plate, with the mode switching motor  15  moving the mode switching plate to a plurality of predetermined mode switching positions, thereby accomplishing the mode switching of the apparatus  1 . 
     It should be noted that reference number  21  represents an amplifier assembly comprising an amplifier that amplifies the recording signal and a wiring board that sends the amplified signal to the rotary cylinder  5 . 
     However, the conventional apparatus  1  having the structure described above has a drawback, in that when the tape cassette is loaded to the cassette holder  7  a static electric charge on the tape cassette is transferred to the cassette holder  7 . As noted previously, the cam  11  of the slider cam assembly  8  that engages the metal shaft that connects the cassette holder  7  and the slider cam assembly  8  is made of a resinous material in order to facilitate the sliding of the shaft  9  therealong. Moreover, the arm  18  that moves the slider cam assembly  9  is also coated with a resinous material for the same purpose. As a result, the static electricity is not discharged externally via the slider cam assembly  8  but instead remains on the cassette holder  7 . The presence of this static electric charge can cause the integrated circuits mounted on the above-described adjacent circuit board to be reset or otherwise operate in a mistaken manner. 
     At the same time, the conventional apparatus  1  as described above has an additional drawback in that, in the process of loading the tape cassette into the cassette holder  7  and moving the slider cam assembly  8  to a predetermined position directly above the amplifier assembly  21 , the slider cam assembly  8  becomes an antenna for radiating electromagnetic waves generated from the wiring board, which can adversely affect the operation of the other electronic components within the apparatus  1 . As a result, conventionally the amplifier assembly  21  is covered with a shield casing not shown in the diagram. However, providing such a shield casing requires the use of valuable space in an apparatus having a dense concentration of electronic components, and is therefore undesirable. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is a general object of the present invention to provide an improved and useful magnetic recording/reproduction apparatus in which the drawbacks described above are eliminated. 
     More specifically, a first object of the present invention is to provide an improved and useful magnetic recording/reproduction apparatus in which a static electric charge on the cassette holder is discharged externally and eliminated with the loading of the tape cassette into the cassette holder. 
     In addition, a second object of the present invention is to provide a magnetic recording/reproduction apparatus in which the slider cam assembly is prevented from acting as an antenna for the radiation of electromagnetic waves generated from the amplifier assembly. 
     The above-described objects of the present invention are achieved by a magnetic recording/reproduction apparatus for magnetically recording information to and/or reproducing information from a recording medium, the magnetic recording/reproduction apparatus having an electrically grounded tape cassette loading/ejecting mechanism, the tape cassette loading/ejecting mechanism comprising: 
     a chassis adapted to be electrically grounded; 
     a cassette holder for loading a tape cassette into and/or ejecting a tape cassette from the apparatus; 
     a slider cam assembly mounted on the chassis and mechanically coupled to the cassette holder for moving the cassette holder to and from a predetermined loading position inside the apparatus; and 
     a static electric charge removal mechanism electrically connected to the cassette holder for removing a static electric charge from the cassette holder. 
     According to this aspect of the invention, because the cassette holder is electrically grounded by the ground terminal the static electricity is discharged externally and eliminated not via the chassis when a static electric charge on the tape cassette is transferred to the cassette holder when the tape cassette is loaded into the cassette holder, thus avoiding damage to or interference with the circuit board due to the presence of a static electric charge. 
     Additionally, the above-described objects of the present invention are also achieved by a magnetic recording/reproduction apparatus for magnetically recording information to and/or reproducing information from a recording medium, the magnetic recording/reproduction apparatus having an electrically grounded tape cassette loading/ejecting mechanism, the tape cassette loading/ejecting mechanism comprising: 
     a chassis adapted to be electrically grounded mounting an electronic component that generates electromagnetic waves; 
     a cassette holder for loading a tape cassette into and/or ejecting a tape cassette from the apparatus; 
     a slider cam assembly mounted on the chassis and mechanically coupled to the cassette holder for moving the cassette holder to and from a predetermined loading position inside the apparatus; and 
     an electromagnetic wave removal mechanism, the electromagnetic wave removal mechanism contacting the slider cam assembly at least when the slider cam assembly has moved the cassette holder to the predetermined loading position inside the apparatus so as to electrically ground the slider cam assembly and cassette holder. 
     According to this aspect of the invention, when the slider cam assembly has moved to a point directly above the amplifier unit and is exposed to electromagnetic waves generated by the amplifier unit, the slider cam assembly is electrically grounded and thus functions not as an antenna but as a shield casing covering the electronic components, eliminating the adverse effects of noise interference on these electronic components. 
     Additionally, the above-described objects of the present invention are also achieved by the magnetic recording/reproduction apparatus as described above, wherein the flexible member of the electromagnetic wave removal mechanism has a substantially comb-like shape. 
     According to this aspect of the invention, each of the individual teeth of the comb-like flexible member flex so as to envelopingly contact the slider cam assembly and thus ground the slider cam assembly securely at multiple points. Additionally, because the slider cam assembly and each of the teeth of the comb-like flexible member form a ground contact, the effectiveness of the ground can be increased by increasing the number of teeth in the comb-like flexible member. 
    
    
     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 perspective view of a conventional magnetic recording/reproduction apparatus; 
     FIG. 2 is a disassembled perspective view of a magnetic recording/reproduction apparatus for explaining a mechanism for removing static electricity and electromagnetic waves according to one embodiment of the present invention; 
     FIG. 3 is a disassembled perspective view from a rear side of the mechanism for removing static electricity and electromagnetic waves shown in FIG. 2; 
     FIGS. 4A and 4B are diagrams showing perspective and edge views of a leaf spring adapted to one embodiment of the present invention; 
     FIGS. 5A and 5B are plan and side views, respectively, of the magnetic recording/reproduction apparatus according to one embodiment of the present invention; 
     FIGS. 6A and 6B are diagrams for explaining a torsion spring adapted to one embodiment of the present invention, showing left lateral views of a slider cam assembly in an advanced position and a retracted position, respectively; 
     FIGS. 7A and 7B are diagrams for explaining a torsion spring adapted to one embodiment of the present invention, showing partial plan views of a slider cam assembly in an advanced position and a retracted position, respectively; and 
     FIGS. 8A and 8B are diagrams for explaining a leaf spring adapted to one embodiment of the present invention, showing right lateral views of a slider cam assembly in an advanced position and a retracted position, respectively. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A description will now be given of a magnetic recording/reproduction apparatus according to one embodiment of the present invention, with reference to the accompanying drawings. It should be noted that identical or corresponding elements are given identical or corresponding reference numbers in all drawings, with detailed descriptions thereof given once and thereafter omitted. In addition, where relevant, for ease of explanation directions in the drawings are given as X 1 -X 2  for a front-to-back direction, Y 1 -Y 2  for the side-to-side direction, and Z 1 -Z 2  for the vertical direction. 
     FIG. 2 is a disassembled perspective view of a. magnetic recording/reproduction apparatus for explaining a mechanism for removing static electricity and electromagnetic waves according to one embodiment of the present invention. FIG. 3 is a disassembled perspective view from a rear side of the mechanism for removing static electricity and electromagnetic waves shown in FIG.  2 . FIGS. 4A and 4B are diagrams showing perspective and edge views of a leaf spring adapted to one embodiment of the present invention. FIGS. 5A and 5B are plan and side views, respectively, of the magnetic recording/reproduction apparatus according to one embodiment of the present invention. 
     The magnetic recording/reproduction apparatus  20 , hereinafter referred to as the apparatus  20 , is substantially similar to the conventional art except for the mechanism for removing static electricity and electromagnetic waves. Accordingly, the following description concentrates on the mechanism for removing static electricity and electromagnetic waves. 
     As described above, the tape cassette loading mechanism  3  comprises a cassette holder  7  and a slider cam assembly  8 , both made of metallic material. The cassette holder  7  has a flat floor panel  7   a  and side walls  7   b  on lateral edges in the Y 1 -Y 2  directions. Each of the side walls  7   b  is provided with a pair of shafts  22   a  and  22   b  near front and rear end portions thereof, the shafts being of different heights. Additionally, a threaded portion is provided at a tip of the shafts  22   b , such threaded portion not, however, being shown in the drawing. 
     Additionally, as shown in the diagram, the slider cam assembly  8  comprises a substantially rectangular base portion  8   a  and a pair of lateral arms  8   b  extending from the base portion  8   a  in an X 1 -X 2  direction. Each of the lateral arms  8   b  is provided with a cam  11  having a cam groove  11   a . A coil spring  26  made of conductive metal that acts as a second connecting means is provided on a rear edge base portion  8   a . One end  26   a  of the coil spring  26  is retained by an aperture formed in the base portion  8   a.    
     Further, L-shaped guide grooves  13  for accommodating the slider cam assembly  8 ,are formed in resinous side walls  12  of the chassis  2 . 
     To install the apparatus  20 , one of the shafts  22   b  of the cassette holder  7  is covered with a coil section  28   a  of a torsion spring  28  made of a conductive metal that is the first connecting means. Next, the shafts  22   a ,  22   b  are fitted to the cam grooves  11   a  of the cam  11  of the slider cam assembly  8 . Then, one end  28   b  of the torsion spring  28  is engaged to a bottom edge of the side wall  7   b  of the cassette holder  7  and the other end  28   c  of the torsion spring  28  is engaged to a top edge of the side wall  8   a  of the slider cam assembly  8 . 
     Then, in order to mount the cassette holder  7  and the slider cam assembly  8  on the chassis  2 , the tips of the shafts  22   a ,  22   b  are fitted into the guide grooves  13  in the side walls  12  of the chassis  2 , bushings  30  are fitted over the tips of the shaft and screws  31  are fitted to the threaded portions in the tips of the shaft  22   b . Additionally, bushings  54  and screws  56  are inserted into straight-line grooves  50  formed toward the rear of the side walls  12 , with the screws screwed into hole portions  52  formed in the side walls  8   b . It should be noted that both the shafts  22   a ,  22   b  and the bushings  30  are made of conductive metal. 
     Once the apparatus  20  has been mounted, the other end  26   b  of the coil spring  26  provided on the base portion  8   a  of the slider cam assembly  8  is retained by a screw  32  provided on the motor bracket  19  and made from a conductive metallic material. It should be noted that the motor bracket  19  is fixedly mounted to the chassis  2  by screws  32  and  32   a.    
     Additionally, a metallic rear wall  34  connected to a ground terminal (not shown in the drawing) is provided at a rear portion of the chassis  2 . A leaf spring  36  made of conductive metallic material is mounted so as to contact the rear wall  34  and project in a forward X 2  direction. 
     A more detailed description will now be given of the leaf spring  36 , with reference to FIGS. 4A,  4 B,  5 A and  5 B. 
     A bottom edge of the leaf spring  36  is bent at a right angle and formed into a bottom flange  36   a , and mounted to an underside of the chassis  2 , toward the rear X 1  side of the chassis  2 . For convenience, a more detailed description of the mounting of the leaf spring  36  on the chassis will be deferred. Additionally, a bottom edge along both lateral ends of the rear wall  34  of the chassis  2  is similarly bent at a right angle and formed into separate bottom flanges  34   a , which are mounted to the underside of the chassis  2  by screws. A separate smaller bottom flange  34   b  between the bottom flanges  34   a  is also similarly screwed into the underside of the chassis  2 , but with the bottom flange  36   a  of the leaf spring  36  sandwiched between the bottom flange  34   b  and the underside of the chassis  2 . The effect of this disposition is to securely adapt the leaf spring  36  and the chassis  2  to be electrically grounded via the rear wall  34  of the chassis  2  once the entire unit is inserted into a magnetic recording/reproduction apparatus such as a DAT. 
     Separately, it should be noted that reference numeral  62  indicates an amplifier unit that is part of the amplifier assembly  21  and which functions to amplify the recording signals. In the present embodiment, the amplifier  62  is positioned outside the rear wall  34 , so the amplifier  62  output is fed into the interior of the unit by using a wiring board  60 . The amplified recording signals flow through the wiring board  60  and thus the wiring board becomes a source of electromagnetic radiation. 
     The bottom of the leaf spring  36  is notched in two places to form projections  42 . When mounting the leaf spring  36  on the chassis  2 , the chassis  2  is slid between the projections  42  and the bottom flange  36   a  of the leaf spring  36 , thus electrically connecting the leaf spring  36  to the chassis  2 . The leaf spring  36  further comprises a base portion  58  for fixedly mounted the leaf spring  36  to the chassis  2  and a flexible portion  61  extending vertically from the base portion  58 . The flexible portion  61  comprises two parallel rows of comb-like teeth  38  extending laterally Y 1 -Y 2  direction, the rows being formed one substantially atop the other with a large open space  40  between the rows as best seen in FIG. 4A. A projecting portion  36   b  projecting toward the rear wall  34 , that is, toward the X 1  direction, is formed at a position in intermediate between the two rows of teeth  38 . 
     A description will now be given of the static electric charge removal mechanism and the electromagnetic wave removal mechanism of the apparatus  20  having the structure described above, in that order. 
     FIGS. 6A and 6B are diagrams for explaining a torsion spring adapted to one embodiment of the present invention, showing left lateral views of a slider cam assembly in an advanced position and a retracted position, respectively. FIGS. 7A and 7B are diagrams for explaining a torsion spring adapted to one embodiment of the present invention, showing partial plan views of a slider cam assembly in an advanced position and a retracted position, respectively. 
     With the cassette holder  7  and the slider cam assembly  8  in the advanced position shown in FIG. 6A, that is, advanced toward the X 2  direction, the shaft  22   b  advances to an upper end of the slanted portion of the cam groove  11   a  of the cam  11 . At this time the torsion spring  28  is disposed so that one end  28   b  thereof is engaged by the bottom edge of the side wall  7   b  of the cassette holder  7  and the other end  28   c  thereof is engaged by a top edge of the slider cam assembly  8 . As a result, the coil portion  28   a  of the torsion spring wound about the shaft  22   b  is twisted slightly, thereby producing a spring force. 
     Similarly, with the cassette holder  7  and the slider cam assembly  8  in the retracted position shown in FIG. 6B, that is, withdrawn toward the X 1  direction, the shaft  22   b  retracts to a straight horizontal portion of the cam groove  11   a  of the cam  11  and the cassette holder  7  drops downward in the Z 2  direction. At this time, the ends  28   b ,  28   c  of the torsion spring  28  slide along the their retaining walls, thereby eliminating the tension in the spring and with it the spring force described above. 
     It should be noted that the coil portion  28   a  of the torsion spring  28  also functions as a compression spring, with the compression so generated constantly pressing the torsion spring against the walls  7   b ,  8   b  of the cassette holder  7  and slider cam assembly  8 , respectively. 
     Accordingly, the torsion spring  28  electrically connects the cassette holder  7  and the slider cam assembly  8 . It should be noted that the spring force exerted in the vertical Z 1 -Z 2  direction by the torsion spring  28  is minimal, as is the surface area of contact between the torsion spring  28  and the walls  7   b ,  8   b . As a result, there is not much dust created by friction as the spring slides along the walls. Additionally, though the spring force of the torsion spring  28  in the vertical Z 1 -Z 2  direction is small, as described above the torsion spring exerts a spring force like that of a compression spring in the Y 1 -Y 2  direction, so the torsion spring  28  securely engages the walls  7   b ,  8   b . It should be noted that the ends  28   b ,  28   c  of the torsion spring are shaped like hooks and thus can be engaged easily without interfering with the smooth operation of the tape cassette loading mechanism  3 . 
     A description will now be given of the coil spring  26 , with reference to FIGS. 7A and 7B. 
     FIGS. 7A and 7B are diagrams for explaining a torsion spring adapted to one embodiment of the present invention, showing partial plan views of a slider cam assembly in an advanced position and a retracted position, respectively. 
     As shown in FIG. 7A, the coil portion  26   c  of the coil spring  26  is compressed when the slider cam assembly  8  is in the advanced position, that is, advanced in the X 2  direction. As shown in FIG. 7B, the coil portion  26   c  of the coil spring  26  is extended when the slider cam assembly  8  is in the retracted position, that is, retracted in the X 2  direction. As noted previously, one end  26   a  of the coil spring  26  is retained by the aperture formed in the base portion  8   a  of the slider cam assembly  8  and the other end  26   b  of the coil spring  26  is retained by the screw  32 . 
     The cassette holder  7  and slider cam assembly  8  are constantly in motion when the apparatus  20  is in use, so the slider cam assembly  8  remains electrically connected to the screw  32  via the coil spring  26 . As noted previously, the screw  32  is electrically connected to the rear wall  34  via the chassis  2  and from there to the ground terminal. 
     The static electric charge removal mechanism described above, the cassette holder  7  is connected to the slider cam assembly  8  via the torsion spring  28 , the slider cam assembly  8  is connected to the screw  32  on the motor bracket  19  via the coil spring  26 , the screw  32  is connected to the chassis  2 , the chassis  2  is connected to the rear wall  34 , and the rear wall  34  is connected to the ground terminal. As a result, the cassette holder  7  is securely grounded. 
     Accordingly, even if the cassette holder  7  acquires a static electric charge, that static electric charge is discharged externally, thereby eliminating the noise generated by the static electricity and preventing the circuit board from malfunctioning. 
     A description will now be given of the electromagnetic wave removal mechanism, with reference to FIGS. 8A and 8B. 
     FIGS. 8A and 8B are diagrams for explaining a leaf spring adapted to one embodiment of the present invention, showing right lateral views of a slider cam assembly in an advanced position and a retracted position, respectively. 
     As shown in FIG. 8A, the leaf spring  36  and a rear end of the base portion  8   a  of the slider cam assembly  8  are separated from each other when the slider cam assembly  8  is in the advanced position, that is, advanced in the X 2  direction. In this case, the slider cam assembly  8  is separated also from the wiring board  60  that carries the amplifier assembly  21  that generates electromagnetic waves, so there is no possibility that the slider cam assembly  8  becomes an antenna for the propagation of electromagnetic waves from the wiring board  60 . 
     However, when the slider cam assembly  8  is in a retracted position as shown in FIG. 8B, that is, retracted in the X 1  direction, a rear end of the base portion  8   a  of the slider cam assembly  8  contacts the leaf spring  36  and a projecting portion  36   b  contacts a rear wall  34 . The projecting portion  36   b  so positioned thus formed a fixed end and generates a spring force. 
     When the slider cam assembly  8  is retracted and the base portion  8   a  of the slider cam assembly  8  is directly above the wiring board  60  as described above and the base portion of the slider cam assembly  8  contacts the leaf spring  36 , the bottom flange  36   a  of the leaf spring  36  is electrically connected to the ground terminally that is connected to the rear wall  34  via the bottom flanges  34   a  of the rear wall  34 . Accordingly, the slider cam assembly  8  does not act as a radiating antenna for the propagation of electromagnetic waves from the wiring board  60  but instead acts as a shield casing for the wiring board  60  and blocking the radiation of electromagnetic waves therefrom. 
     Additionally, as can be appreciated from the diagrams, a length L 2  of substantially the entire leaf spring  36  is greater than a length L 1  of the upper part of the leaf spring  36 , so the spring constant is increased and the spring force of the leaf spring  36  as a whole is enhanced, thereby improving the contact between the rear. end of the base portion  8   a  and the leaf spring  36 . 
     Additionally, the teeth  38  of the slider cam assembly  8  leaf spring  36  are by definition individually formed and can therefore bend independently to accommodate the rear end of the base portion  8   a  of the slider cam assembly  8  even if the base portion  8   a  contacts the leaf spring  36  not cleanly but at an angle to the leaf spring  36 . The practical effect is that the electrical grounding of the slider cam assembly  8  is improved. 
     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. 11-229809, filed on Aug. 16, 1999, the entire contents of which are hereby incorporated by reference.