Abstract:
According to the structure of a conventional magnetic recording/reproducing apparatus, the loading and unloading of a cartridge are effected by pushing the cartridge into the apparatus manually against the biasing force of a plate spring which serves as a cartridge holding member, thus requiring a large force (about 0.5 to 1 Kgf) for the cartridge loading and unloading operation. In the magnetic recording/reproducing apparatus of the present invention, a slide member having retaining rollers is attached to a housing slidably and the retaining rollers are brought into engagement with engaging portions of a cartridge. In this state the slide member is allowed to slide to effect loading and unloading of the cartridge.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a magnetic recording/reproducing apparatus. Particularly, the invention is concerned with a loading and unloading mechanism for a cartridge with a magnetic tape received therein. 
     2. Description of the Prior Art 
     A conventional magnetic recording/reproducing apparatus  21  will be described below with reference to FIG. 24 which is a plan view of the apparatus, FIG. 25A which is a sectional view taken on line A—A in FIG. 24, and FIG. 25B which is a side view of a principal portion thereof. 
     In the conventional magnetic recording/reproducing apparatus  21  (hereinafter referred to as the “apparatus  21 ”), a pair of guide members  21   b  and  21   c  each having a U-shaped groove are attached in an opposed relation to each other to right and left side faces of a base plate  21   a.    
     In the vicinity of the guide members  21   b  and  21   c , openings  21   d  are formed in portions of the base plate  21   a , as shown in FIG.  25 A. 
     On the back of the base plate  21   a  are mounted a pair of plate springs  22  having a strong resilience, the plate springs  22  being screwed at one end thereof and free at the opposite end. At the tip of the free end of each plate spring  22  is formed a retaining portion  22   a  and a roller  22   b  is supported rotatably by the retaining portion  22   a.    
     The roller  22   b  is inserted into the associated opening  21   d  of the base plate  21   a.  When a strong depressing force is applied to the roller  22   b,  the strong resilience of the plate spring  22  permits the roller  22   b  to move vertically within the opening  21   d  with the foregoing screwed portion of the plate spring as fulcrum. 
     A cartridge  23 , with a magnetic tape  23   a  accommodated therein, has guide grooves  23   b  formed in both side faces thereof, as shown in FIG.  25 B. The guide grooves  23   b  are guided by the guide members  21   b  and  21   c  to conduct the cartridge  23  into the apparatus  21 . 
     In portions of a bottom plate  23   c  which constitutes the guide grooves  23   b  of the cartridge  23  there are formed cutout portions  23   d.    
     For loading the cartridge  23  into the apparatus  21 , first the front end portion of the cartridge is inserted manually in the direction of arrow B from an inlet  21   e  of the apparatus. 
     As a result, the front end portion of the bottom plate  23   c  of the cartridge  23  comes into abutment with the rollers  22   b.  But if the cartridge  23  is pushed into the apparatus  21  with a stronger force, the plate springs  22  deflect downward, whereby the rollers  22   b  are forced down. 
     By virtue of the resilience of the plate springs  22  the rollers  22   b  come into elastic contact with one end of each of the cutout portions  23   d.    
     In this way one end of each of the cutout portions  23   d  is pressed in the direction of arrow A (45°) by the rollers  22   b,  whereby the cartridge  23  is held in the interior of the apparatus  21  while it is prevented from coming off the apparatus. In this state, a magnetic head  24  and the magnetic tape  23   a  are in abutment with each other, now ready for recording and reproduction. 
     For unloading the cartridge  23  from the apparatus  21 , the operator is required to pull a rear end portion  23   e  of the cartridge, which projects from the inlet  21   e  to the exterior of the apparatus, manually in the direction of arrow C against the biasing force of the plate springs  22 , allowing the rollers  22   b  to be disengaged from the cutout portions  23   d  of the cartridge  23 , whereby the cartridge can be removed from the apparatus  21 . 
     In the above conventional apparatus  21 , however, since the loading and unloading of the cartridge  23  are performed by hand, a fairly strong force (about 0.5 to 1 Kgf) is required against the biasing force of the plate springs  22 . In order to facilitate the loading and unloading of the cartridge  23 , the resilience of the plate spring  22  may be weakened, but in this case the force for holding the cartridge in the apparatus  21  becomes weaker, and when vibration or the like is exerted on the apparatus from the exterior, the magnetic tape  23   a , which is in sliding contact with the magnetic head  24 , may move, or the cartridge  23  may no longer be held in place. Once such a state occurs, it may become impossible to effect accurate recording and reproduction. 
     SUMMARY OF THE INVENTION 
     For solving the above-mentioned problems, according to the present invention there is provided, in the first aspect thereof, a magnetic recording/reproducing apparatus including a loading and unloading mechanism which makes it possible for a cartridge with a magnetic tape received therein to be loaded and unloaded with respect to the apparatus, also including a slide member capable of engaging the cartridge, and further including a housing for holding the slide member, the loading and unloading of the cartridge being effected by sliding the slide member in an engaged state thereof with the cartridge. 
     In the second aspect of the present invention there is provided, in combination with the apparatus in the first aspect, magnetic recording/reproducing apparatus wherein the slide member is held slidably with respect to the housing and in such a manner that when the slide member lies on a cartridge inlet side, engaging portions thereof for engagement with the cartridge can be engaged with and disengaged from the cartridge in a direction orthogonal to the sliding direction. 
     In the third aspect of the present invention there is provided, in combination with the apparatus in the second aspect, a magnetic recording/reproducing apparatus wherein the engagement of the slide member with the cartridge is effected by engagement of retaining portions formed as protuberances on the slide member side with engaging grooves formed on the cartridge side, the retaining portions of the slide member being displaceable vertically with respect to the sliding direction. 
     In the fourth aspect of the present invention there is provided, in combination with the apparatus in the third aspect, a magnetic recording/reproducing apparatus wherein the retaining portions of the slide member are constituted by rollers supported on one end side of the slide member. 
     In the fifth aspect of the present invention there is provided, in combination with the apparatus in the fourth aspect, a magnetic recording/reproducing apparatus wherein the slide member is formed with stoppers at positions near the rollers, the stoppers being higher than the rollers. 
     In the sixth aspect of the present invention there is provided, in combination with the apparatus in the second aspect, a magnetic recording/reproducing apparatus wherein the housing is provided with cam portions to displace the slide member into engagement with and disengagement from the cartridge. 
     In the seventh aspect of the present invention there is provided, in combination with the apparatus in the sixth aspect, a magnetic recording/reproducing apparatus wherein the cam portions are formed integrally with the housing by projecting portions of the housing downward. 
     In the eighth aspect of the present invention there is provided, in combination with the apparatus in the fourth aspect, a magnetic recording/reproducing apparatus wherein when the rollers are positioned on the lower side with a vertical motion of the slide member, the rollers come into contact with end portions of the engaging grooves of the cartridge to lock the cartridge temporarily. 
     In the ninth aspect of the present invention there is provided, in combination with the apparatus in any of the first to seventh aspects, a magnetic recording/reproducing apparatus wherein the housing is provided with a drive source and a rotary cam mechanism connected to the drive source, and the slide member is driven electrically by the rotary cam mechanism. 
     In the tenth aspect of the present invention there is provided, in combination with the apparatus in any of the first to eighth aspects, a magnetic recording/reproducing apparatus wherein in a cartridge loading position the whole of the cartridge is loaded completely into the housing. 
     In the eleventh aspect of the present invention there is provided a magnetic recording/reproducing apparatus including a loading and unloading mechanism which makes it possible for a cartridge with a magnetic tape received therein to be loaded and unloaded with respect to the apparatus, also including a slide member capable of engaging the cartridge, further including an electric drive means for sliding the slide member, a housing for holding the slide member, and a sensor for detecting that the cartridge has been inserted into the housing, wherein when it is detected by the sensor that the cartridge has been inserted into the housing, the electric drive means is operated to start sliding of the slide member for completing the loading of the cartridge. 
     In the twelfth aspect of the present invention there is provided, in combination with the apparatus in the eleventh aspect, a magnetic recording/reproducing apparatus wherein the housing is provided with a slidable opening member for opening a lid of the cartridge and wherein, after the cartridge has been inserted and its lid opened by the opening member, the opening member is allowed to slide with a further cartridge inserting motion, and this sliding of the opening member is detected by the sensor to detect that the cartridge has been inserted, whereupon the operation of the electric drive means is started. 
     In the thirteenth aspect of the present invention there is provided, in combination with the apparatus in the eleventh aspect, a magnetic recording/reproducing apparatus wherein an opening member for opening a lid of the cartridge is fixed to the housing and wherein, when it is detected by the sensor that the lid has been opened and that the cartridge has been inserted, the operation of the electric drive means is started. 
     In the fourteenth aspect of the present invention there is provided, in combination with the apparatus in the eleventh aspect, a magnetic recording/reproducing apparatus wherein the slide member is held slidably with respect to the housing and in such a manner that when the slide member lies on a cartridge inlet side, engaging portions thereof for engagement with the cartridge are movable in a direction orthogonal to the sliding direction. 
     In the fifteenth aspect of the present invention there is provided, in combination with the apparatus in the fourteenth aspect, a magnetic recording/reproducing apparatus wherein the engagement of the slide member with the cartridge is effected by engagement of retaining portions constituted by rollers with engaging grooves formed in the cartridge, the said rollers being supported on one end side of the slide member and displaceable vertically with respect to the sliding direction. 
     In the sixteenth aspect of the present invention there is provided, in combination with the apparatus in the fifteenth aspect, a magnetic recording/reproducing apparatus wherein the slide member is formed with stoppers at positions near the rollers, the stoppers being higher than the rollers 
     In the seventeenth aspect of the present invention there is provided, in combination with the apparatus in any of the eleventh to thirteenth aspects, a magnetic recording/reproducing apparatus wherein the electric drive means comprises a motor and a transfer mechanism. 
     In the eighteenth aspect of the present invention there is provided a magnetic recording/reproducing apparatus including a loading and unloading mechanism which makes it possible for a cartridge with a magnetic tape received therein to be loaded and unloaded with respect to the apparatus, also including a slide member capable of engaging the cartridge, and further including a housing for holding the slide member, wherein the slide member is provided with a stopper mechanism for stopping the cartridge at a position of engagement with the slide member upon insertion of the cartridge into the apparatus and which stopper mechanism, when the slide member is pulled in, permits movement of the cartridge while maintaining the engaged state of the cartridge with the slide member. 
     In the nineteenth aspect of the present invention there is provided, in combination with the apparatus in the eighteenth aspect, a magnetic recording/reproducing apparatus wherein the stopper mechanism is formed integrally with the slide member. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an explanatory view showing the whole of a magnetic recording/reproducing apparatus according to an embodiment of the present invention; 
     FIG. 2 is an explanatory view showing a completed state of cartridge loading in the magnetic recording/reproducing apparatus; 
     FIG. 3 is a plan view of a housing used in the magnetic recording/reproducing apparatus; 
     FIG. 4 is a sectional view showing a principal part of a cam portion of the housing illustrated in FIG. 3; 
     FIG. 5 is a perspective view of a slide member used in the magnetic recording/reproducing apparatus; 
     FIG. 6 is a perspective view of a cartridge used in the magnetic recording/reproducing apparatus; 
     FIG. 7 comprises a front view, a side view and a bottom view of a spur gear used in the magnetic recording/reproducing apparatus; 
     FIG. 8 is a perspective view of a cam plate used in the magnetic recording/reproducing apparatus; 
     FIG. 9 is a plan view of principal portions in a waiting state for cartridge loading in the magnetic recording/reproducing apparatus; 
     FIG. 10 is a plan view of principal portions in a cartridge loaded state in the magnetic recording/reproducing apparatus; 
     FIG. 11 is an explanatory view showing a relation between a slide plate and a cam portion in a waiting state for cartridge loading in the magnetic recording/reproducing apparatus; 
     FIG. 12 is a sectional view of principal portions for explaining an engaged state of a roller with the cartridge at the beginning of cartridge loading in the magnetic recording/reproducing apparatus; 
     FIG. 13 is a sectional view of principal portions for explaining a roller-cartridge engaged state at the beginning of cartridge loading in the magnetic recording/reproducing apparatus; 
     FIG. 14 is a sectional view of principal portions for explaining a roller-cartridge engaged state at completed loading of the cartridge in the magnetic recording/reproducing apparatus; 
     FIG. 15 is a sectional view of principal portions for explaining the operation of an opening member and that of a sensor at the beginning of cartridge loading in the magnetic recording/reproducing apparatus; 
     FIG. 16 is a sectional view of principal portions for explaining the operation of the opening member and one of the sensor at the beginning of cartridge loading in the magnetic recording/reproducing apparatus; 
     FIG. 17 is a sectional view of principal portions for explaining the operation of the opening member and one of the sensor at completed loading of the cartridge in the magnetic recording/reproducing apparatus; 
     FIG. 18 is a plan view of principal portions for explaining the operation of the opening member and one of the sensor at the beginning of cartridge loading illustrated in FIG. 15; 
     FIG. 19 is a plan view of principal portions for explaining the operation of the opening member and one of the sensor at the beginning of cartridge loading illustrated in FIG. 16; 
     FIG. 20 is an explanatory view showing a completed state of cartridge loading in a magnetic recording/reproducing apparatus according to another embodiment of the present invention; 
     FIG. 21 is a plan view of principal portions for explaining the operation of a cartridge sensor used in a magnetic recording/reproducing apparatus according to a further embodiment of the present invention; 
     FIG. 22 is a sectional view of principal portions for explaining the operation of a cartridge sensor used in a magnetic recording/reproducing apparatus according to a still further embodiment of the present invention; 
     FIG. 23 is a sectional view of principal portions for explaining the operation of a stopper member used to prevent overrunning of a cartridge in a magnetic recording/reproducing apparatus according to a still further embodiment of the present invention; 
     FIG. 24 is a plan view of principal portions for explaining a loaded state of a cartridge into a conventional magnetic recording/reproducing apparatus; and 
     FIG. 25 comprises a sectional view of principal portions and a side view of principal portions for explaining the cartridge loaded state in the conventional magnetic recording/reproducing apparatus. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Magnetic recording/reproducing apparatus embodying the present invention will now be described with reference to FIGS. 1 to  23 . As shown in FIGS. 1 and 2, a magnetic recording/reproducing apparatus  1  (hereinafter referred to as the apparatus  1 ) substantially comprises a housing  2  which is generally rectangular in external shape and in the interior of which are mounted various components to be described later, and a cover  17  for closing an upper portion of the housing  2 , with a cartridge inlet  1   a  being formed in a front portion of the housing. 
     At side faces of a cartridge  4 , which accommodates a magnetic tape therein and which is to be loaded into the apparatus  1 , there are formed guide portions  4   f  and  4   e  in an up-and-down relation to each other for guiding the cartridge into the apparatus  1 . In the lower guide portions  4   e  are formed engaging grooves  4   g  for engagement and locking therein of retaining portions  3   e  of a slide member  3 . FIG. 2 is an appearance view at completed loading of the cartridge  4  into the apparatus  1  with the retaining portions of the slide member engaged in the grooves  4   g.    
     A more detailed construction of the apparatus  1  will be described with reference to FIGS. 3 to  10 . 
     The housing  2  is constituted by a metallic plate for example. As shown in a plan view of FIG. 3, the housing  2  is formed in a rectangular external shape and it comprises a bottom plate  2   a  and side plates  2   b,    2   b  formed opposedly to each other by bending the bottom plate  2   a  upward (to this side perpendicularly to the paper surface of FIG.  3 ). 
     In two right and left positions of the bottom plate  2   a  are punched a pair of openings  2   c ,  2   c  with a press or the like. In the openings  2   c ,  2   c  are formed tongue-like cam portions  2   d ,  2   d,  respectively, to constitute inclined portions projecting obliquely downward from the bottom plate  2   a,  as shown in FIG.  4 . 
     Thus, portions of the housing  2  are projected to the back side of the bottom plate  2   a  to form the cam portions  2   d  as the above inclined portions integral with the housing. 
     Between the two openings  2   c ,  2   c  shown in FIG. 3 is formed a head mounting hole  2   e  by punching. At positions adjacent to the head mounting hole  2   e  are formed two stoppers  2   f  by cutting and raising portions of the bottom plate  2   a  upward (to this side perpendicularly to the paper surface of FIG.  3 ). 
     Further, an arcuate guide slot  2   g  is formed through the bottom plate  2   a.    
     Rivet mounting apertures  2   j  are formed in the bottom plate  2   a  at positions near the openings  2   c ,  2   c  and also near the guide slot  2   g.  Additionally, around the guide slot  2   g  are formed a plurality of circular apertures of a small diameter. 
     The slide member  3  is disposed in contact with a back side  2   h  of the bottom plate  2   a.    
     The slide member  3  is constituted by a metallic plate having resilience such as a stainless steel plate. As shown in a perspective view of FIG. 5, the slide member  3  is generally U-shaped in external form and comprises a base portion  3   a  and arm portions  3   b ,  3   c  extending forward from both right and left sides of the base portion  3   a.    
     Tips of the arm portions  3   b  and  3   c  are bent upward at right angles from the outside to form a pair of roller holding portions  3   d  in an opposed relation to each other. 
     Retaining portions are formed respectively at the tips of the paired roller holding portions  3   d ,  3   d.  The retaining portions are constituted respectively by metallic, retaining rollers  3   e ,  3   e  which are supported rotatably by shafts. 
     In the vicinity of the roller holding portions  3   d  and through the arm portions  3   b ,  3   c  are formed elongated sliding slots  3   f ,  3   f  respectively by punching so that their longitudinal directions are parallel to each other. Nearly centrally of the base portion  3   a  is also formed a sliding slot  3   g  by punching in a direction parallel to the sliding slots  3   f.  On the right-hand side of the sliding slot  3   g  in FIG. 5 is formed an elliptical aperture  3   h  in a direction orthogonal to the sliding slot  3   g.    
     The arm portions  3   b  and  3   c  are of the same length and their front ends  3   j  and  3   k  are formed in a rectilinear shape. The roller holding portions  3   d ,  3   d  extend forward beyond the front ends  3   j  and  3   k.    
     As shown in FIGS. 9 and 10, the slide member  3  of such a construction is mounted slidably to the back side  2   h  of the bottom plate  2   a  of the housing  2  with rivets  2 K. 
     For mounting the slide member  3  to the back side of the bottom plate  2   a , the housing  2  shown in FIG. 3 is turned inside out so that the back side  2   h  faces up. Then, the roller holding portions  3   d  of the slide member  3  with the retaining rollers  3   e  attached thereto are aligned with the two openings  2   c  of the bottom plate  2   a  and inserted therein. Then, alignment is made so that the front ends  3   j  and  3   k  of the slide member  3  do not strike on the slants of the cam portions  2   d  of the bottom plate  2   a.    
     Further, the three rivet mounting apertures  2   j  are aligned respectively with the sliding slots  3   f ,  3   f  and  3   g  formed in the slide member  3 , and the tips of rivets  2   k  having head portions of a diameter larger than the width of each sliding slot are inserted into those sliding slots and rivet mounting apertures. 
     The rivets  2   k  thus inserted into the rivet mounting apertures  2   j  of the housing  2  are then caulked and fixed to the bottom plate  2   a  with a caulking jig (not shown), whereby the slide member  3  is attached slidably to the back side  2   h  of the housing  2 . 
     As shown in FIG. 6, the cartridge  4  to be loaded into the apparatus  1  receives therein a magnetic tape  4   a , which is wound round rotatable reels  4   b ,  4   b.    
     A cutout portion  4   j  is formed centrally of a front side  4   c  of the cartridge  4 , and a pinch roller  4   d  is disposed so that its outer peripheral portion partially overhangs the cutout portion  4   j  . The reels  4   b,    4   b  rotate in interlock with rotation of the pinch roller  4   d,  thereby making it possible to wind up or wind back the magnetic tape  4   a.    
     At both right and left outer side faces of the cartridge  4  are formed guide portions  4   e  and  4   f  in an up-and-down relation to each other to guide the cartridge  4  into the apparatus  1 . 
     The right and left lower guide portions  4   e  respectively have engaging grooves  4   g  formed by partially cutting out the guide portions. 
     On the right-hand side in the figure of the front side  4   c  of the cartridge  4  is disposed a lid  4   h  capable of being opened and closed. With the lid  4   h  open, the magnetic tape  4   a  is exposed. 
     At a position closer to the right-hand corner in the figure with respect to the position of the lid  4   h  there is disposed a support pin  4   m  which supports the lid pivotably. A torsion coil spring (not shown) is wound round the support pin  4   m  to urge the lid  4   h  in its closing direction resiliently at all times. 
     An end portion  4   n  of the lid  4   h  is projected on the right-hand side of the cartridge relative to the support pin  4   m.  When the end portion  4   n  is pressed from the front, the lid  4   h  turns around the support pin  4   m  to open the right-hand portion of the front side  4   c  of the cartridge  4 . 
     As shown in FIG. 9, a motor mounting plate  5  is secured with bolts or the like to the bottom plate  2   a  of the housing  2 , and an electric motor  6  for sliding the slide member  3  is mounted to the motor mounting plate  5 . That is, the electric motor  6  is used as a drive source for sliding the slide member  3 . 
     A pinion gear  6   a  is mounted on the shaft of the motor  6  and the rotation of the motor is transmitted to gears  7  via the pinion gear  6   a.  The gears  7  comprise a pinion gear  7   a,  a worm gear  7   b  integral with the pinion gear  7   a,  and pinion gears  7   c,    7   d  each comprising two pinion gears of different diameters formed integrally with each other, which pinion gears and worm gear are in a mutually engaged state. The gears  7  thus constituted are fitted through respective shaft portions into apertures of a small diameter formed in the vicinity of the guide slot  2   g.    
     Upon rotation of the motor  6 , the rotational force is transmitted to a cam mechanism  8  having a spur gear  9  via the gears  7 . 
     The cam mechanism  8  comprises a spur gear  9  and a cam plate  10 . As shown in FIG. 7, the spur gear  9  is circular in external form and has a plurality of tooth threads  9   a  formed on its outer periphery. The gear of a smaller diameter in the pinion gear  7   d  is in mesh with the tooth threads  9   a  to transmit the rotation of the motor  9  to the cam mechanism  8 . 
     A projection  9   b  of a generally triangular shape is formed on the surface of the spur gear  9  at a position close to the outer periphery of the surface. 
     On the back side of the spur gear  9  is formed a cam groove  9   c  of a generally arcuate shape at predetermined width and depth in such a manner that the distance from the rotational center gradually becomes larger clockwise in FIG. 7A from near a central hole  9   d  up to near the tooth threads  9   a  formed on the outer periphery side. 
     In the cam mechanism  8 , moreover, a rotatable cam plate  10 , which converts the rotational motion of the spur gear  9  into a linear motion, is disposed between the spur gear  9  and the bottom plate  2   a  of the housing  2 . 
     As shown in FIG. 8, the, cam plate  10  has a generally L-shaped external form. On one side of the cam plate  10 , a cam pin  10   a  of a circular section is projected upward at one end portion, and a support shaft  10   b  is projected downward at the rotational center of the cam plate. Further, at an end portion on the opposite side of the cam plate  10 , a slide pin  10   c  of a circular section is projected downward in the same direction as the support shaft  10   b.  The cam pin  10 , support shaft  10   b  and slide pin  10   c  are secured to the cam plate  10  by caulking and the like. 
     In the cam plate  10  of such a construction, the support shaft  10   b  is attached rotatably to the bottom plate  2   a,  as shown in FIG.  9 . The slide pin  10   c  of the cam plate  10  is fitted through the arcuate guide slot  2   g  movably and its tip is inserted into the elliptical aperture  3   h  formed in the slide member  3 . 
     The tip of the slide pin  10   c  projects downward through the aperture  3   h  and a washer (not shown) is caulked thereto. The slide member  3  is connected slidably to the tip of the slide pin  10   c  so as to prevent dislodgment thereof. 
     The cam pin  10   a  is slidably engaged with the cam groove  9   c  of the spur gear  9 . 
     In the cam mechanism  8  of such a construction, when the spur gear  9  rotates in the counterclockwise direction, the cam pin  10   a  of the cam plate  10  moves in a direction away from the rotational center of the spur gear  9  following the contour of the cam groove  9   c  of the spur gear  9 . 
     As a result, the cam plate  10  rotates counterclockwise about the support shaft  10   b  and the slide pin  10   c  moves in the arcuate guide slot  2   g  of the housing  2  in the direction of arrow E, causing the slide member  3  to slide in the arrow E direction. 
     As shown in FIG. 9, a magnetic head  11  is mounted within the head mounting hole  2   e  of the housing  2 . At a predetermined position spaced from the magnetic head  11  is disposed a conveyance roller  12  for winding the magnetic tape  4   a.  With a motor (not shown) or the like as a drive source, the conveyance roller  12  is rotated clockwise and counterclockwise, thereby making it possible to wind up and wind back the magnetic tape  4   a.    
     As shown in FIG. 1, the upper portion of the housing  2  is covered with a cover  17  to close the interior of the magnetic recording/reproducing apparatus  1 . In a front portion of the apparatus  1  is formed a cartridge inlet  1   a,  through which the cartridge  4  can be conducted smoothly into the apparatus. 
     In the interior of the housing  2  shown in FIG. 9 are disposed cartridge guide members (not shown) for guiding the insertion of the cartridge  4  along the side plates  2   b.  In the cartridge guide member located on one side, an elongated opening member  13  for opening the lid  4   h  of the cartridge  4  is disposed slidably. 
     The opening member  13  is formed by molding and the like. As shown in FIG. 15, a lid opening portion  13   a  is formed arcuately at an end portion of the opening member  13  so as to be positioned near the cartridge inlet  1   a  of the apparatus  1 . 
     The opening member  13  also has a pressing portion  13   b  projecting upward on the right-hand side in the figure of the lid opening portion  13   a.  When the cartridge  4  is inserted into the apparatus, the pressing portion  13   b  is pressed by an end portion on the front side  4   c  of the cartridge, whereby the opening member  13  is made slidable. 
     On the right-hand side of the pressing portion  13   b  is formed a coil spring retaining portion  13   c,  and at a rightmost end in the figure is formed a switch input portion  13   d  as a lower stepped portion. 
     One end of a coil spring  14  is anchored at the coil spring retaining portion  13   c  of the opening member  13 , while the opposite end thereof is fixed to the cartridge guide member (not shown). Consequently, the slidable opening member  13  is urged resiliently in the direction of arrow F at all times by virtue of the coil spring  14 . 
     Above the switch input portion  13   d  formed on the right-hand side of the opening member  13 , a sensor  15 , say, a push switch, is secured to a printed circuit board  16 . When the opening member slides in the direction of arrow E and the switch input portion  13   d  pushes the detector  15  upward to turn ON the sensor, the sliding motion of the opening member  13  is detected by the sensor  15  and thus the insertion of the cartridge  4  can be detected. 
     The printed circuit board  16  is mounted with bolts or the like to mounting portions (not shown) formed by cutting and bending the side plates  2   b  of the housing  2 . The printed circuit board  16  is also covered with the cover  17 . 
     The operation of the magnetic recording/reproducing apparatus  1  of the above construction embodying the present invention will be described below with reference to FIGS. 9 to  19 . 
     In the apparatus  1  which is in a stand-by state before insertion of the cartridge  4 , as shown in FIG. 11, the front ends  3   j  ( 3   k ) of the slide member  3  strike on the slants of the cam portions  2   d  projecting from the bottom plate  2   a  of the housing  2 . Further, the roller holding portions  3   d  sink downward and the retaining rollers  3   e  are positioned approximately half within the openings  2   c.  The front ends  3   j  ( 3   k ) of the slide member  3  are moved up and down by the cam portions  2   d,  whereby the retaining rollers  3   e  as the foregoing retaining portions can be engaged with and disengaged from the engaging grooves  4   g  of the cartridge  4 . 
     Thus, while the apparatus is in a stand-by state for the insertion of cartridge, the retaining portions of the slide member for engagement with the cartridge are displaceable in a direction orthogonal to the sliding direction of the slide member. 
     The following description is now provided about the operation for loading the cartridge into the apparatus  1 . 
     First, the cartridge  4 , which is indicated with a dash-double dot line in FIG. 9, is pushed in lightly in the direction of arrow E from the cartridge inlet  1   a  formed on the front side of the apparatus  1 , by manual operation of the operator. As a result, the guide portions  4   e  and  4   f  formed on both right and left sides of the cartridge  4  are guided by the guide members disposed on both right and left sides in the interior of the housing  2 , and the end portion  4   n  of the cartridge lid comes into abutment with the lid opening portion  13   a  of the opening member  13  in the interior of the housing  2 , as shown in FIGS. 15 and 18. 
     With a further insertion of the cartridge  4  into the housing  2 , the end portion  4   n  of the lid  4  is pressed against the lid opening portion  13   a  of the opening member  13  and turns in the direction of arrow D in FIG. 18 with the support pin  4   m  as fulcrum, so that the front side  4   c  of the cartridge  4  is opened partially. 
     On the other hand, with the insertion of the cartridge  4 , the front ends of the cartridge guide portions  4   e  strike against the retaining rollers  3   e , as shown in FIG.  12 . However, since the retaining rollers  3   e  are positioned on the lower side under the action of the cam portions  2   d,  the cartridge  4  can be further pushed into the apparatus  1  with a light force of small resistance. At this time, the retaining rollers  3   e  are somewhat depressed by the guide portions  4   e.    
     As the cartridge  4  is further inserted into the housing  2 , the lid  4   h  assumes a forwardly straight state with respect to the front side  4   c  of the cartridge and thus becomes parallel to the opening member  13 , as shown in FIG.  19 . 
     In this state, if the cartridge  4  is further inserted into the housing  2 , the front side  4   c  of the cartridge comes into abutment with the pressing portion  13   b  of the opening member  13 . 
     With a still further insertion of the cartridge  4  into the apparatus  1 , as shown in FIG. 16, the opening member  13  moves, against the resilience of the coil spring  14 , inwards together with the cartridge  4  and the switch input portion  13   d  of the opening member  13  turns ON the sensor  15  such as a push switch, attached to the printed circuit board  16  positioned above, to detect that the cartridge  4  has been inserted into the apparatus  1 . 
     Thus, a further insertion of the cartridge  4  after opening of the lid causes the opening member  13  to slide, and this sliding motion is detected by the sensor  15  to detect that the cartridge  4  has been inserted. 
     Once the insertion of the cartridge  4  is detected by the sensor  15 , the operation of the drive source  6  such as a motor for example is started. 
     At this time, the relation between the retaining rollers  3   e  as the retaining portions of the slide member  3  and the engaging grooves  4   g  of the cartridge  4  is such that the retaining rollers  3   e  come to be positioned in the engaging grooves  4   g  from their state shown in FIG. 12 in which the retaining rollers strike on ends of the guide portions  4   e.  Thus, the insertion of the cartridge  4  gives rise to a click feeling. 
     As soon as the retaining rollers  3   e  are positioned in the engaging grooves  4   g  of the cartridge  4 , the sensor  15  is turned ON and the operation for inserting the cartridge  4  into the apparatus  1  is switched over from manual operation to electric drive using the drive source  6  such as a motor for example. 
     Thus, once the drive source  6  starts operating, the spur gear  9  of the cam mechanism  8  is rotated counterclockwise in FIG. 9 via gears  7 , and the cam plate  10  rotates counterclockwise about the support shaft  10   b  while following the contour of the cam groove  9   c  of the spur gear  9 . 
     As a result, the pin  10   c  of the cam plate  10  moves along the guides slot  2   g  of the housing  2  and the slide member  3  begins to move in the direction of arrow E. 
     Once the movement of the slide member  3  in the arrow E direction starts, as shown in FIG. 13, the front ends  3   j  ( 3   k ) of the slide member  3  slide down from the slants of the cam portions  2   d  of the housing  2 , and the arm portions  3   b,    3   c  become parallel to the back side of the bottom plate  2   a  by virtue of the resilience of the slide member  3 . 
     In this state, the retaining rollers  3   e  of the slide member  3  are engaged completely in the engaging grooves  4   g  of the cartridge  4  to retain the cartridge. Further, as the slide member  3  slides in the arrow E direction, the cartridge  4  is pulled into the apparatus  1 . 
     Next, when the spur gear  9  further rotates in the counterclockwise direction, the top of the apex of the triangular projection  9   b  of the spur gear turns ON a slide position detecting switch (not shown) which is provided on the printed circuit board  16  located above the spur gear and which is for detecting a slide position in the loading direction, with the result that the drive source  6  turns OFF. At this time, as shown in FIG. 10, the pin  10   a  on the cam plate  10  engaged in the cam groove  9   c  of the spur gear  9  is positioned approximately on the outermost periphery side, and the pin  10   c,  which is in an engagement anti-dislodgmentwise with the slide member  3 , moves up to the outermost side in the arrow E direction of the guide slot  2   g  of the housing  2 . When the slide member  3  has thus been pulled in up to the innermost part of the apparatus  1 , the sliding motion of the slide member  3  in the arrow E direction stops. 
     With such a movement of the slide member  3  to the inner part of the apparatus  1 , the pinch roller  4   d  of the cartridge  4  comes into abutment with the conveyance roller  12  disposed in the interior of the apparatus  1 , and the magnetic tape  4   a  comes into sliding contact with the magnetic head  11 . 
     When the cartridge  4  is pulled in by the drive source  6 , as shown in FIG. 17, the opening member  13  is pulled in the arrow E direction together with the cartridge, and the coil spring  14  is in a stretched state, while the sensor  15  remains ON. 
     As mentioned above, the cartridge  4  comes into abutment with the conveyance roller  12  and its sliding motion stops. To be more specific, the slide member  3  moves a little more in the arrow E direction and then stops in order to prevent slippage with respect to the pinch roller. 
     Therefore, as shown in FIG. 14, the retaining rollers  3   e  of the slide member  3  somewhat strike on the side walls of the guide portions  4   e  with the engaging grooves  4   g  formed therein and are located at lower positions to retain the cartridge  4 . 
     Once the sliding motion of the cartridge  4  and that of the slide member  3  stops, recording and reproduction for the magnetic tape  4   a  can be done any time in accordance with a command issued from an external computer (not shown) for example. 
     When the loading of the cartridge  4  is over, the rear end portion of the cartridge is exposed to the extent that it can be held by the operator, as shown in FIG.  2 . 
     Thus, in the apparatus  1  of this embodiment, by only the sliding motion of the slide member  3  toward the inner part of the apparatus, the cartridge  4  can be loaded into the apparatus  1  and positioned and held therein. 
     The following description is now provided about an eject operation for taking out the cartridge from the inside of the apparatus  1 . In accordance with an eject command issued from an external computer (not shown) or the like, the drive source  6  is turned ON and is rotated in the direction opposite to the rotational direction in the loading of the cartridge  4 , thereby causing the spur gear  9  to rotate clockwise from its state shown in FIG.  10 . 
     Further, the cam plate  10  is rotated clockwise and the pin  10   c  is moved in the arrow F direction, thus causing the slide member  3  to slide toward the cartridge inlet  1   a  (in the arrow F direction). The slide member  3  and the cartridge  4  are returned to their positions shown in FIGS. 9 and 12. 
     As a result, the apex of the triangular projection  9   b  of the spur gear  9  turns ON a slide position detecting switch (not shown) which is provided on the printed circuit board  16  and which is for detecting a slide position in the eject direction, resulting in that the rotation of the drive source  6  is stopped to stop the movement in the arrow F direction of the slide member  3 . 
     Then, as shown in FIG. 15, the cartridge  4  moves to the front side of the apparatus  1  relative to the position where the sensor  15  turns ON, with the resilience of the coil spring  14  which is anchored at the opening member  13 . In this state, the retaining rollers  3   e  of the slide member  3  are in a temporarily engaged state in the engaging grooves  4   g  of the cartridge  4 , as shown in FIG. 12, so that the cartridge can be easily taken out from the apparatus  1  manually and with a light force. 
     Upon completion of the cartridge extracting operation, the apparatus  1  assumes a stand-by state waiting for insertion of the cartridge  4 . 
     If the motor  6  as the drive source or the cam mechanism  8  fails during the cartridge eject operation from the apparatus  1  and the cartridge  4  is left behind within the apparatus, the operator is required to pull out the cartridge while holding a rear side  4 K of the cartridge, whereby the holding portions  3   d  are deflected downward and hence the cartridge can be taken out. Thus, the cartridge  4  is employable without any trouble. 
     If a resilient member for urging the cartridge  4  in a direction to eject it to the exterior of the apparatus  1  is provided separately and the cartridge is ejected by the resilient member, it is possible to further improve the operability. 
     Referring now to FIG. 20, there is illustrated another embodiment of the present invention, in which the whole of the cartridge  4  is loaded completely into the housing  2 . In this case, there is no portion of the cartridge  4  projecting from the apparatus  1  to the exterior and therefore there is no fear of, for example, the operator&#39;s hand striking against the cartridge by mistake which would cause a deviation in the abutment position between the tape and the head. Further, in applications not requiring frequent replacement of cartridge, particularly in a data backup unit of a computer, the cartridge may be left loaded in the apparatus over a long period. Even in such a case, this embodiment permits suppressing the deterioration of performance caused by the entry of dust or the like. Thus, it is possible to effect recording and reproduction with a high reliability. 
     Referring now to FIGS. 21 and 22, there is illustrated a further embodiment of the present invention in which the body of a cartridge is detected directly and then the loading of the cartridge is started. 
     In the embodiment illustrated in FIG. 21, an opening member  13 ′ is formed integrally with a cartridge guide member (not shown) which is fixed in the interior of the housing  2  to guide the insertion of a cartridge  4 . A sensor  15  is attached to the opening member  13 ′ in an opposed relation to an opening position of a lid  4   h  of the cartridge  4 . 
     When the cartridge  4  is inserted into the apparatus  1  of such a construction and the lid  4   h  is opened by the fixed opening member  13 ′, the surface of the lid  4   h  pushes ON the sensor  15  attached to the opening member  13  and constituted by a push switch or the like, whereby it is detected that the cartridge  4  has been inserted into the apparatus. Then, a drive source  6  such as a motor is turned ON. 
     The sensor  15  may be attached to an upper case  17  or printed circuit board  16 , as shown in FIG.  22 . According to this construction, when the cartridge  4  is further inserted into the apparatus  1  after the lid  4   h  has been opened by the opening member  13 ′, an upper end portion of the lid  4   h  pushes ON the sensor  15 . 
     By turning ON of the sensor  15  it is detected that the cartridge  4  has been inserted into the apparatus, whereupon the operation of the drive source such as a motor is started to perform the loading operation. 
     Thus, since the sensor is provided correspondingly to the lid opening position of the cartridge, it is possible to surely detect insertion of the cartridge and opening of the lid without using any other separate member. 
     Now, with reference to FIG. 23, a description is directed to a magnetic recording/reproducing apparatus according to a still further embodiment of the present invention which apparatus is provided with stoppers for preventing the overrun of a cartridge at the time of insertion of the cartridge. 
     In the apparatus of this embodiment, a slide member  3  is integrally formed with stopper portions  3   m  by press working so as to be located at a more inside position than roller holding portions  3   d  and higher than retaining rollers  3   e  of the slide member  3 . 
     The stopper portions  3   m  are formed so that they can stop insertion of a cartridge  4  at a position where the retaining rollers  3   e  are engaged in retaining grooves  4   g  of the cartridge  4 . 
     During the manual insertion of the cartridge  4  into the apparatus, there may occur an overrun of the cartridge  4  being pushed too much into the apparatus  1  with the force of inertia. However, the tips of guide portions  4   e  of the cartridge  4  come into abutment with the stopper portions  3   m  of the slide member  3 , whereby the movement of the cartridge  4  into the housing  2  is stopped. 
     Thus, it is unlikely at all that the cartridge  4  will be pushed excessively into the apparatus  1  and that the retaining rollers  3   e  once engaged in the engaging grooves  4   g  will come off the same grooves and stop while striking on the surfaces of the guide portions  4   e  located on the rear side of the cartridge. It is, therefore, possible to effect the loading of the cartridge positively. Besides, there is no fear of an increase of the motor load at the beginning of the loading. 
     In the magnetic recording/reproducing apparatus of the present invention, as set forth hereinabove, since the slide member is brought into engagement with engaging portions of a cartridge, allowing the cartridge to slide and be loaded to and ejected from the apparatus with sliding motions of the slide member, the cartridge can be loaded to and ejected from a recording/reproducing position of the apparatus easily and securely. 
     Further, by operating the slide member with use of an electric drive source, it becomes possible to effect an automatic loading of the cartridge and hence possible to provide a magnetic recording/reproducing apparatus superior in operability.