Patent Publication Number: US-6341049-B1

Title: Cassette loading mechanism

Description:
FIELD OF THE INVENTION 
     The present invention relates to cassette loading mechanisms for use in magnetic recording-playback devices such as VTRs for removably loading a cassette onto the chassis of the device. 
     BACKGROUND OF THE INVENTION 
     FIG. 9 is a perspective view of a cassette  6  and a tray  3  for holding the cassette  6  as will be described below. The tray  3  has wall plates  32 ,  32  provided upright at opposite sides thereof and each having two pins  30 ,  31  projecting outward therefrom. The tray  3  has a lug  33  projecting upward from its front end and to be pushed by the front end of the cassette  6 . 
     The present applicant has previously disclosed a cassette loading mechanism shown in FIG. 10 ( see U.S. Pat. No. 5,535,071). The tray  3  described is provided inwardly of side plates  2  disposed upright on a chassis  1  and has its pins  30 ,  31  fitted in respective first and second guide slits  20 ,  21  formed in the side plate  2 . 
     Three gears  5 ,  50 ,  51  are arranged on the outer side of the side plate  2 . The gear  51  in the most downstream position is provided with a leg  52  having the pin  31  of the tray  3  fitted therein. When the gear  5  in the most upstream position is rotatingly driven, the gear  51  rotates, moving the tray  3  along the guide slots  20 ,  21 . 
     Projecting from a side wall of the chassis  1  are a pair of support members  9 ,  9 . A loading member  4  extending in the cassette loading direction for driving the tray  3  has the support members  9 ,  9  fitted therein. The loading member  4  is formed with mount openings  92 ,  92  for the two corresponding support members  9 ,  9  to fit in and with a rack  40  at its upper end. Each support member  9  comprises a shank  90  and a head  91  of increased diameter at the outer end of the shank. The mount opening  92  comprises a slit  93  extending in the cassette loading direction and a large hole  94  formed at one end of the slit  93  for the head  91  to fit in. 
     In mounting the loading member  4  on the chassis  1 , the head  91  of each support member  9  is positioned as opposed to the large hole  94  of the corresponding mount opening  92 , and the loading member  4  is fitted around the support member  9 . Next, the loading member  4  is moved toward a cassette ejecting direction a distance a (see FIG. 10) to cause the shank  90  to fit into the slit  93 . The loading member  4  is prevented from slipping off the chassis  1  by the head  91  of the support member  9 . The side plate  2  provided with the gear  5 , etc. is thereafter attached to the chassis  1 . The gear  5  is in mesh with the rack  40  when the mechanism is in condition for the start of cassette loading. 
     Provided on the rear side of the chassis  1  is an operation gear  10  rotatable by a motor (not shown) and meshing with teeth  53  projecting from the lower end of the loading member  4 . The rotation of the operation gear  10  is transmitted to the gear  5  by the loading member  4 . 
     FIGS. 11A and 11B are right side elevations of the cassette loading mechanism, FIG. 11A showing the mechanism in a standby state for cassette loading, FIG. 11B showing the mechanism during cassette loading. When the cassette  6  is placed onto the tray  3  in the standby state, a cassette-in sensor switch (not shown) disposed on the path of travel of the tray  3  is turned on, whereupon the operation gear  10  (see FIG. 10) is rotated. This moves the loading member  4  and the tray  3 , loading the cassette  6  in place. 
     However, the conventional cassette loading mechanism has the following problems. 
     When used singly, the support member  9  is unable to support the loading member  4  with good stability, so that the loading member  4  needs to be supported by at least two support members  9 ,  9  which are arranged at different locations. 
     Since the mount openings  92 ,  92  of the loading member  4  are arranged side by side along the cassette loading direction as seen in FIG. 10, the loading member  4  becomes elongated and large-sized. The chassis  1  provided with the support members  9 ,  9  is also large-sized. 
     Further the loading member  4  is fitted around each support member  9  and then moved toward the cassette ejecting direction a distance a for mounting. If this distance a is short, however, the loading member  4  is likely to slip off the chassis  1  when the chassis  1  is subjected to an impact while attaching the side plate  2  to the chassis  1 . The distance a therefore needs to be great. This also makes the loading member  4  and the chassis  1  large-sized. Whereas it is required that such a magnetic recording-playback device be compact in its entirety, the loading member  4  and the chassis  1  which are large-sized are in conflict with this requirement. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to compact the member for driving the tray and the chassis. 
     A side plate  2  disposed upright on a chassis  1  is provided with engaging pieces  8 ,  80  parallel to each other and corresponding to an upper end and a lower end of a loading member  4 . 
     The loading member  4  is formed, in the end thereof corresponding to one of the engaging pieces  8 ,  80 , with a cutout  49  for permitting the loading member  4  to move to inside the engaging piece  80  when positioned for mounting on the side plate  2 . 
     The loading member  4  is mounted on the side plate  2  by fitting the end thereof not having the cutout  49  to the other engaging piece  8  of the side plate  2  and causing the other end of the loading member  4  to clear the engaging piece  80  at the cutout  49  and to move to inside of the engaging piece  80 . The loading member  4  is slidable from the mounted position to move within a range in which the loading member  4  is in engagement with the side plate  2 . 
     The engaging pieces  8 ,  80  are provided on the side late  2  in corresponding relation with the upper end and the lower end of the loading member  4  and therefore serve to make the loading member more compact than in the conventional mechanism wherein the two mount openings in the loading member are arranged side by side along the loading direction. 
     When the loading member  4  is positioned for mounting on the side plate  2 , the upper end or lower end of the loading member  4  is in engagement with the engaging piece  8 . Accordingly, the loading member  4  can be engaged with the side plate  2  by sliding the member  4  from the mounting position such a distance that the upper or lower end of the loading member  4  which is out of engagement in the mounting position is engaged by the other engaging piece  80 . 
     When in the mounting position, the conventional loading member  4  is not engaged with the chassis  1  and is therefore likely to slip off the support members  9 ,  9  unless the distance a the member  4  is to be moved from the mounting position is great (see FIG.  10 ). According to the present invention, however, the loading member  4 , when positioned for mounting, has its upper or lower end already engaged with the side plate  2  and is less likely to slip off inadvertently from this position. This shortens the distance a the loading member  4  is to be slidingly moved from the mounting position for engagement with the side plate  2 , consequently compacting the loading member  4  and the chassis  1  having the side plate  2 . 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view of a cassette loading mechanism; 
     FIG. 2 is a front view of the cassette loading mechanism; 
     FIG. 3A is a perspective view of a loading member, and FIG. 3B is a rear view of the loading member; 
     FIGS. 4A and 4B are right side elevations of the cassette loading mechanism, FIG. 4A showing the mechanism on completion of cassette loading, FIG. 4B showing the same in a standby state for cassette loading; 
     FIGS. 5A and 5B are right side elevations of the cassette loading mechanism with a cassette placed therein, FIG. 5A showing the position relationship between the loading member and a pivotal lever, FIG. 5B showing the position relationship between the loading member and a torsion spring; 
     FIG. 6A is a view in section partly broken away and showing the loading member when the member is to be mounted on a side plate, and FIG. 6B is a side elevation showing a loading member mounted position; 
     FIG. 7A is a view in section showing the position relationship between an elastic piece and the loading member when the loading member is to be mounted on the side plate, and FIG. 7B is an enlarged view showing the loading member in engagement with a second engaging piece on the side plate; 
     FIG. 8 is a view in section partly broken away and showing a side plate and a loading member according to another embodiment; 
     FIG. 9 is a perspective view of the cassette and a tray; 
     FIG. 10 is an exploded perspective view of a conventional cassette loading mechanism; and 
     FIGS. 11A and 11B are right side elevations of the conventional cassette loading mechanism, FIG. 11A showing the mechanism in a standby state for cassette loading, FIG. 11B showing the same in the course of cassette loading. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the invention will be described below in detail with reference to the drawings concerned. 
     [Overall Construction] 
     FIG. 1 is an exploded perspective view of a cassette loading mechanism, and FIG. 2 is a front view of the mechanism as it is seen from the cassette insertion side thereof. 
     Provided upright on a chassis  1  is a slide plate  2  which is formed with first and second guide slots  20 ,  21  for pins  30 ,  31  on a tray  3  to fit in respectively. Although FIG. 1 shows two guide slots  20 ,  21 , the number of slots is not limited to two, but three slots may be provided for the tray  3  to move with good stability. 
     Another side plate  2  is provided also at the left side of the chassis  1  (see FIG.  2 ), and the two side plates  2 ,  2  are interconnected by a top plate  25  and a connecting rod  24  disposed at the lower end of the side plates  2 . Disposed inwardly of each side plate  2  is a pivotal lever  7  having a base end fitting to the connecting rod  24  and a forward end formed with a slit  71 , which has the pin  31  of the tray  3  fitted therein. A fitting pin  70  projects outward from a portion of the pivotal lever  7  away from its midportion toward the base end and extends through a circular-arc aperture  22  formed in the side plate  2 . 
     A cassette inlet between the side plates  2 ,  2  is provided with a door  65  pivoted at its upper end to the side plates  2  (see FIGS.  4 A and  4 B), and a door opener (not shown) for opening the door  65  has a base end fitted to the connecting rod  24 . 
     A loading member  4  in the form of a plate is disposed externally of and opposed to the side plate  2  shown in FIG.  1 . The side plate  2  is provided with a first engaging piece  8  extending in the cassette loading direction between the first and second guide slots  20 ,  21  thereof. Projecting from a lower end portion of the side plate  2  is a bent lug  81  positioned externally of the chassis  1  and having an outwardly bent lower end. The bent lug  81  has at its outer extremity an upward projection  82 . The bent lug  81  and the projection  82  provide a second engaging piece  80 . The loading member  4  is engageable with the first and second engaging pieces  8  and  80 . 
     Provided on the rear side of the chassis  1  is an operation gear  10  disposed under the second engaging piece  80  and rotatable by a motor (not shown). The operation gear  10  is in mesh with a rack  40  inwardly projecting from the lower end of the loading member  4 . Projecting from the inner surface of the loading member  4  is a holder  46  positioned above the rack  30 . The second engaging piece  80  fits in between the holder  46  and the rack  40 . 
     An elastic piece  26  having an outwardly projecting upper end is provided on the side plate  2  in front of the first engaging piece  8 . The elastic piece  26  is pushed in by the loading member  4  when the member  4  is mounted. 
     Contact pins  44 ,  44  facing inward are provided on the loading member  4  at upper end portions thereof. The inner ends of the contact pins  44 ,  44  are in contact with the side plate  2 , with the upper end of the loading member  4  engaged with the first engaging piece  8  (see FIG.  2 ). A guide pin  45  projecting inward from a front end portion of the loading member  4  fits in a guide channel member  23  on the side plate  2  for guiding the movement of the loading member  4  in the cassette loading direction. 
     Formed in the midportion of the loading member  4  is a cam groove  41  having a lower end opened as at  42  and extending obliquely upward from the opening  42 . The fitting pin  70  of the pivotal lever  7  has its outer end fitted in the cam groove  41 . With reference to FIGS. 4A and 4B which are right side elevations of the side plate  2 , the fitting pin  70  is opposed to the opening  42  of the cam groove  41  on completion of cassette loading as seen in FIG. 4A, while the fitting pin  70  is positioned at an upper end portion of the cam groove  41  when the mechanism is in a standby state for cassette loading. A rib  27  extending in the cassette loading direction is disposed between the first engaging piece  8  and the second guide slot  21 . With the loading member  4  mounted on the side plate  2 , the left contact pin  44  fits in between the first engaging piece  8  and the rib  27  (see FIG.  6 B). 
     [Details of the Loading Member] 
     FIG. 3A is a perspective view of the loading member  4 , and FIG. 3B is a view showing the loading member  4  as it is seen from the rear side thereof. A window  43  is formed in the loading member  4  slightly above its center portion and is continuous with the upper end of the cam groove  41 . When the mechanism is in the standby state for cassette loading, the fitting pin  70  is exposed from the window  43 . A torsion spring  55  is provided on the loading member  4  at its center portion and has one leg  56  extending toward the window  43 . In the standby state for cassette loading, the fitting pin  70  holds the torsion spring  70  deflectively deformed, with the pivotal lever  7  turned by the pin  31  on the tray  3  as will be described later. 
     As shown in FIGS. 3B and 2, the holder  46  comprises a horizontal plate  47  and a latch plate  48  extending downward from the inner end of the plate  47 . The latch plate  48  has a cutout  49  in the end thereof toward the cassette ejection side. 
     [Mounting the Loading Member] 
     The loading plate  4  is mounted on the side plate  2  by the following procedure. 
     FIG. 6A is a sectional view partly broken away and showing the loading member  4  while it is to be mounted on the side plate  2 , with the tray  3  omitted from the illustration. FIG. 6B is a side elevation showing the position where the loading member  4  is to be mounted. FIG. 7A is a view in section showing the position relationship between the elastic piece  26  and the loading member  4  when the loading member  4  is to be mounted on the side plate  2 , and FIG. 7B is an enlarged view showing the loading member  4  in engagement with a second engaging piece  80  on the side plate  2 . 
     First, the tray  3  is moved to a position where it is located on completion of cassette loading. As shown in FIG. 6B, the pins  30 ,  31  on the tray  3  are at the lower ends of the respective first and second guide slots  20 ,  21 , and the fitting pin  70  of the pivotal lever  7  is in contact with the clockwise end of the circular-arc apertured portion  22  of the side plate  2 . Subsequently, the loading member  4  is brought to the mounting position wherein the fitting pin  70  of the pivotal lever  7  is opposed to the opening  42  of the cam groove  41 , and the contact pin  44  toward the loading direction is opposed to the elastic piece  26 . At this time, the cutout  49  in the latch plate  48  of the loading member  4  is opposed to the projection  82  of the side plate  2 , permitting the latch plate  48  to move to inside the projection  82 . 
     As shown in FIG. 6A, the loading member  4  is lowered from the mounting position once and then inserted into the first engaging piece  8  obliquely from below, causing the first engaging piece  8  to engage the upper end of the member  4 . The contact pin  44  at the left fits in between the first engaging piece  8  and the rib  27 , and the loading member  4  has it upper end engaged with the side plate  2 . The loading member  4  in this state is pushed in toward the side plate  2 . As shown in FIG. 7A, the contact pin  44  toward the cassette loading direction deflects and deforms the elastic piece  26  by pushing. Further as seen in FIG. 7B, the latch plate  48  advances to inside the projection  82 , permitting the second engaging piece  80  to fit in between the horizontal plate  47  of the loading member  4  and the rack  40  thereof. The rack  4  of the loading member  4  meshes with the operation gear  10 . 
     The loading member  4  is thereafter moved toward the cassette ejecting direction. The latch plate  48  of the loading member  4  is engaged by the projection  82 . The loading member  4  is prevented from slipping off the chassis  1  by the first and second engaging pieces  8 ,  80 . When the loading piece  4  is further moved toward the cassette ejecting direction, the fitting pin  70  of the pivotal lever  7  moves along the cam groove  41  as shown in FIG. 4B, moving the tray  3  to the standby position for cassette loading. 
     [Safety Mechanism for Cassette Loading] 
     When the user inserts a cassette  6  into the tray  3  in the standby position for cassette loading, the cassette  6  moves the tray  3  by pushing a lug  33  (see FIG. 9) of the tray  3 . The cassette  6  is not loaded immediately at this time, but cassette loading is started after the tray  3  as pushed in by the cassette  6  a predetermined amount has been detected, thus preventing the cassette  6  from being loaded before it is fully inserted. This procedure will be described below. 
     FIGS. 5A and 5B are side elevations showing the side plate  2  and the loading member  4  immediately after the start of cassette loading. The tray  3  pushed in by the cassette  6  moves the pivotal lever  7  clockwise. 
     However, the lever fitting pin  70  extending through the circular-arc aperture  22  in the side plate  2  moves through the window  43  of the loading member  4 , merely deforming the torsion spring  55  by deflection and permitting the loading member  4  to remain at rest without rotating the operation gear  10  on the chassis  1 . 
     When the tray  3  has been pushed in by the predetermined amount, a cassette sensor switch (not shown) disposed on the path of travel of the tray  3  is pushed and turned on, rotating the motor coupled to the operation gear  10 . The loading member  4  meshing with the operation gear  10  moves the cassette loading direction. When the user releases the cassette  6  from the hand, the torsion spring  55  restores itself, and the tray  3  holding the cassette  6  thereon moves toward a loading completed position. 
     The pins  30 ,  31  of the tray  3  are positioned at the lower ends of the respective first and second guide slots  20 ,  21  on completion of loading as previously stated and as shown in FIG.  4 A. At this time, the front end of the loading member  4  is brought close to the side edge of the elastic piece  26 . This eliminates the likelihood of the loading member  4  moving to the mounted position (see FIG.  6 B), preventing the member  4  from slipping off the side plate  2 . Thus, the elastic piece  26  serves as a stopper for preventing the loading member  4  from slipping off inadvertently. 
     The loading member  4  is removable for a repair by pushing in the elastic piece  26  with the finger for deflective deformation and then moving the loading member  4  to the mounting position. 
     The engaging pieces  8 ,  80  are provided on the side plate  2  in corresponding relation with the upper end and the lower end of the loading member  4  and therefore serve to make the loading member  4  more compact than in the conventional mechanism wherein the two mount openings in the loading member  4  are arranged side by side along the loading direction. 
     Although the cutout  49  is formed in the lower end of the loading member  4  according to the present embodiment, the cutout  49  may be formed in the upper end of the loading member  4 , with the first and second engaging pieces  8 ,  80  arranged in the reverse relation (not shown). 
     Alternatively, the loading member  4  may be provided with the first engaging piece  8  and the second engaging piece  80  and thereby caused to be engaged by the side plate  2  as shown in FIG.  8 . In this case, the cutout  49  is formed in the side plate  2 , such that the upper end of the side plate  2  is first fitted to the first engaging piece  8 , and the second engaging piece  80  is then moved through the cutout  49  of the side plate  2  to inside thereof to mount the loading member  4  on the side plate  2 .