Abstract:
A tilt-swivel stand includes a base member, a movable member mounted on the base member, and a connecting mechanism for connecting the base member to the movable member. The connecting mechanism consists of a protrusion and a guide groove into which the protrusion is inserted. The protrusion includes a shank and an engaging portion. This engaging portion has a normal size greater than the width of the guide groove. The engaging portion is flexible enough to go through the guide groove.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a tilt-swivel stand. In particular, it relates to a tilt-swivel stand to support e.g. a CRT (cathode ray tube) for moving the screen of the CRT both in a vertical plane (tilt) and in a horizontal plane (swivel).  
           [0003]    2. Description of the Related Art  
           [0004]    An example of conventional tilt-swivel stands is disclosed in JP-A-6(1994)-189229. The conventional stand, as shown in FIG. 10 of the accompanying drawings, is provided with a base  50  placed on e.g. a desk, and a movable member  60  upon which a CRT is mounted.  
           [0005]    The base  50  is provided at its upper portion with a concave supporting surface  51  coinciding with a part of the surface of a sphere. An upright protrusion  52  extends at the center of the supporting surface  51 . The movable member  60  is provided at its lower portion with a convex slide surface  61  whose curvature is equal to that of the above-mentioned concave surface  51 . The slide surface  61  is formed with an elongated guide groove  62  to receive the protrusion  52  of the base  50 . The width of the groove  62  is slightly greater than the outer diameter of the protrusion  52 .  
           [0006]    In the assembled state, the concave surface  51  is held in sliding engagement with the convex slide surface  61 , with the protrusion  52  extending into the guide groove  62 . A screw  70  with a sufficiently large head is driven into the upper portion of the protrusion  52  to prevent the movable member  60  from coming off the base  50 .  
           [0007]    With the above arrangement, the movable member  60  is still allowed to tilt on the base  50  as the protrusion  52  is moved along the groove  62 . Also, the movable member  60  can be swiveled about the protrusion  52  with respect to the base  50 , at whatever position the protrusion  30  is located within the guide groove  62 .  
           [0008]    However, in the conventional tilt-swivel stand, the screw  70  is used for holding the base  50  and the movable member  60  together. Unfavorably, driving the screw  70  into the prescribed portion requires for an additional procedure in the assembly line. Also, to use the screw  70  will raise the production costs.  
           [0009]    Another example of conventional tilt-swivel stands is disclosed in JP-A-8(1996)-140017. As shown in FIG. 11 of the accompanying drawings, the conventional stand includes a base (not shown) and a movable member  80  held in sliding engagement with the base, as in the previous conventional stand (FIG. 10). The tilt-swivel stand of FIG. 11 is different from the previous one in that no screw is used for attaching the movable member  80  to the base.  
           [0010]    Specifically, as shown in FIG. 11, an upright protrusion  90  is arranged at the center of the base, and a guide groove  81  is formed in the movable member  80  for receiving the upright protrusion  90 . The upright protrusion  90  is formed with several fins  90   a  projecting radially. The guide groove  81  has a uniform width except for one end  81   a  at which a generally circular through-hole is formed.  
           [0011]    For attaching the movable member  80  to the non-illustrated base, the protrusion  90  is inserted into the guide groove  81  at the enlarged end  81   a.  The end  81   a  is large enough to allow the fins  90   a  to go beyond the groove  81 . Then, the movable member  80  is caused to slide on the base, so that the fins  90   a  are moved from the end  81   a  to the constant-width portion  81   b,  as shown in FIG. 11. In this state, some of the horizontally projecting pins  90   a  are caught by the movable member  80 , thereby securing the movable member  80  to the non-illustrated base.  
           [0012]    With such an arrangement, no additional fixing means such as a screw is needed, which is advantageous to reducing the number of parts necessary for assembling the tilt-swivel stand. Consequently, the production costs and production time are both reduced.  
           [0013]    Though the tilt-swivel stand of FIG. 11 has the above advantages, it has been found disadvantageous in the following point.  
           [0014]    As long as the protrusion  90  is located in the constant-width portion  81   b  of the groove  81 , the movable member  80  is prevented from coming off the non-illustrated base due to the fins  90   a  abutting on the movable member  80 . However, the protrusion  90  may be brought to the enlarged portion  81   a  of the groove  81  when the user tilts the CRT mounted on the movable member  80  too much. This unusual positioning of the protrusion  90  relative to the groove  81  is invisible to the user since an CRT is placed on the movable member  80 . Thus, unaware of the current situation, the user may try to move the CRT to a different location and lift it. However, with the stopping fins  90   a  located at the enlarged portion  81   a  of the groove, the non-illustrated base may come off the movable member  80  and may fall onto the desk.  
         SUMMARY OF THE INVENTION  
         [0015]    The present invention has been proposed under the circumstances described above, and its object is to provide a tilt-swivel stand which can be readily assembled and does not suffer from accidental detachment of the movable member from the base.  
           [0016]    According to the present invention, there is provided a tilt-swivel stand including: a base member provided with a concave surface having a predetermined curvature; a movable member mounted on the base member and provided with a convex surface having a curvature equal to the curvature of the concave surface; and connecting means for connecting the base member to the movable member. The connecting means includes a protrusion and a guide groove which has a predetermined width. The protrusion includes a shank and an engaging portion which has a normal size greater than the width of the guide groove. The engaging portion is flexible enough to go through the guide groove.  
           [0017]    With such an arrangement, the movable member is readily attached to the base member simply by pressing the protrusion into the guide groove. The flexible engaging portion is reduced in overall size as it is going through the guide groove, and then restores on its own to the original shape after passing by the guide groove. In this position, the engaging portion is caught by the member in which the guide groove is formed (that is, the movable member or base member), thereby holding together the movable member and the base member.  
           [0018]    In the assembled state, the movable member is mounted on the base member, with the convex surface of the former held in sliding engagement with the concave surface of the latter. The guide groove into which the protrusion is inserted for restriction of movement is typically straight, thereby allowing the movable member to move in a vertical plane (that is, “tilt”) relative to the base member. How far the movable member can be tilted depends upon the length of the guide groove.  
           [0019]    Though the tilting movement is restricted by the configuration of the guide groove, as stated above, basically the rotation of the protrusion relative to the guide groove is not limited by the geometry of the groove. This means that rotation of the protrusion relative to the guide groove can take place at any position in the groove.  
           [0020]    According to a preferred embodiment of the present invention, the shank of the protrusion includes a diametrically larger portion and a diametrically smaller portion. The diametrically larger portion is substantially equal in size to the width of the guide groove.  
           [0021]    With such an arrangement, the protrusion is properly guided by the guide groove when the diametrically larger portion of the protrusion is held in the guide groove.  
           [0022]    According to a preferred embodiment of the present invention, the protrusion is provided on the movable member, while the guide groove is provided on the base member.  
           [0023]    Alternatively, the protrusion may be provided on the base member, while the guide groove may be provided on the movable member.  
           [0024]    Preferably, the protrusion may have an anchor-like configuration. Specifically, the engaging portion may include a pair of engaging pieces which are non-parallel to each other. Each of the engaging pieces may be a generally rectangular plate, though the present invention is not limited to this.  
           [0025]    The tilt-swivel stand of the present invention may further includes stopping means for restricting rotation of the movable member relative to the base member. Preferably, the stopping means may include a profiled element and a stopping wall. The profiled element may be arranged adjacent to the protrusion, while the stopping wall may be arranged adjacent to the guide groove.  
           [0026]    Preferably, the profiled element may be provided with a generally rectangular portion and a semi-cylindrical portion.  
           [0027]    Other features and advantages of the present invention will become apparent from the detailed description given below with reference to the accompanying drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0028]    [0028]FIG. 1 is a sectional side view showing a tilt-swivel stand according to a first embodiment of the present invention;  
         [0029]    [0029]FIG. 2 is a bottom view showing the tilt-swivel stand of FIG. 1;  
         [0030]    [0030]FIG. 3 is a sectional view taken along lines III-III in FIG. 1;  
         [0031]    [0031]FIG. 4 is an enlarged sectional side view showing principal portions of the tilt-swivel stand shown in FIG. 1;  
         [0032]    [0032]FIG. 5 is an enlarged sectional side view showing principal portions of the tilt-swivel stand shown in FIG. 3;  
         [0033]    [0033]FIG. 6A is a view taken along lines VI-VI in FIG. 4;  
         [0034]    [0034]FIG. 6B is a plan view showing the stopper in FIG. 6A;  
         [0035]    [0035]FIG. 7 illustrates how the tilt-swivel stand works;  
         [0036]    [0036]FIG. 8 is a sectional side view showing a tilt-swivel stand according to a second embodiment of the present invention;  
         [0037]    [0037]FIG. 9 is a sectional view taken along lines IX-IX in FIG. 8;  
         [0038]    [0038]FIG. 10 is an exploded view showing an example of conventional tilt-swivel stand; and  
         [0039]    [0039]FIG. 11 is a schematic plan view showing another example of conventional tilt-swivel stand.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0040]    The preferred embodiments of the present invention will be described below with reference to the accompanying drawings.  
         [0041]    Reference is first made to FIGS.  1 - 7  illustrating a tilt-swivel stand according to a first embodiment of the present invention. Basically, the stand (generally indicated by reference numeral  1 ) includes a base  10  to be placed on e.g. a desk, and a movable member  20  mounted on the base  10 . Each of the base  10  and the movable member  20  is a one-piece component which may be made of a resin material.  
         [0042]    As seen from FIGS.  1 - 3 , the base  10  is provided with a leg portion  11 , which is circular as viewed from above (or below). As shown in FIG. 1, the leg portion  11  has a predetermined height H. The upper surface  11   a  of the leg portion descends toward the periphery of the leg portion. The leg portion  11  is not a completely solid body but rather hollow for reduction in weight. For improving the mechanical strength, the leg portion  11  is provided with a plurality of reinforcing ribs  17 , as shown in FIG. 2.  
         [0043]    The base  10  is provided at its upper portion with a slide surface  12  having a circular profile, as viewed from above. The slide surface  12  is (a part of) a concave surface, which is configured to snugly hold a sphere S (see FIG. 1 or  3 ). As viewed from above, the center of the slide surface  12  coincides with the center of the leg portion  11 . The slide surface  12  is the top surface of a cylindrical wall portion  13  extending upright from the leg portion  11 . The height of the wall portion  13  may be smaller than the height H of the leg portion  11 .  
         [0044]    A partition wall  14  is provided slightly below the slide surface  12  to be connected to the inner surface of the wall portion  13 . As seen from FIG. 1 or  3 , the partition wall  14  is so configured as to snugly engage the surface of a sphere (not shown) which is concentric with but slightly larger than the above-mentioned sphere S.  
         [0045]    As shown in FIGS.  1 - 6 A, the partition wall  14  is formed with an elongated guide groove  16  having a predetermined width W (FIGS. 4 and 6A). Below the partition wall  14  is provided a pair of ribs  15  for reinforcing the wall  14 . The ribs  15  extend in parallel to the guide groove  16  which is located between these ribs. As best shown in FIGS. 4 and 6A, a pair of ribs  18  are provided on the upper surface of the partition wall  14 . These ribs  18  also extend in parallel to the guide groove  16 , with the groove located between them. The height of the ribs  18  is short enough to avoid contact with the sphere S.  
         [0046]    Referring to FIG. 1, the movable member  20  is provided with an upper surface  21  to be connected to a CRT. The lower surface  22  of the movable member is a convex surface coinciding with a part of the surface of the sphere S. Thus, the lower surface  22  is snugly supported by the slide surface  12  of the base  10 , as illustrated in the figure. The movable member  20  is large enough to keep the lower surface  22  in proper engagement with the slide surface  12  after the movable member  20  has been tilted relative to the base  10  within a predetermined range.  
         [0047]    The movable member  20  is formed integrally with a downward protrusion  30  located at the center of the lower surface  22 . As best shown in FIGS. 4 and 5, the protrusion  30  is divided into three portions: a base portion  31 , an intermediate portion  32  and an end portion  33 . The base portion  31  and the intermediate portion  32  both have a circular cross section, but the former is greater in diameter than the latter. The diameter of the base portion  31  is slightly smaller than the width W of the guide groove  16 . Thus, the base portion  31  is movable along the guide groove  16 , while also rotatable within the groove.  
         [0048]    The intermediate portion  32 , which is axially longer than the base portion  31 , connects the base portion  31  to the end portion  33 .  
         [0049]    The end portion  33  is formed with first and second anchoring arms  33   a,    33   b.  As seen from FIGS. 4 and 5, each of the arms  33   a,    33   b  is a generally rectangular plate, which is appropriately flexible, as will be described later. The length of each arm is L1, as shown in FIG. 5. In FIG. 4, the first arm  33   a  extends upward and to the left, while the second arm  33   b  extends upward and to the right. The maximum width of the end portion  33  is L2. According to the present invention, the length L1 and the width L2 are both greater than the width W of the guide groove  16 . With such an arrangement, the first and second arms  33   a,    33   b  come into abutment with the partition wall  14 , whatever angles the protrusion  30  is rotated (swiveled) through in the guide groove  16 . Thus, the movable member  20  is advantageously prevented from accidentally coming off the base  10 .  
         [0050]    As shown in FIGS.  4 - 6 A, the lower surface  22  of the movable member  20  is integrally formed with a profiled solid element or stopper  40  adjacent to the base portion  31  of the protrusion  30 . In cooperation with a stopping wall or rib, the stopper  40  serves to restrict the rotation of the movable member  20  relative to the base  10 , as described below.  
         [0051]    Referring to FIGS. 6A and 6B, the stopper  40  is divided into a generally rectangular portion  40 L and a semi-cylindrical portion  40 R. The rectangular portion  40 L is formed with two round corners  40   b,  while the semi-cylindrical portion  40 R is formed with a semi-cylindrical surface  40   a.  The center of the semi-cylindrical portion  40 R coincides with the center of the base portion  31  and intermediate portion  32 . As shown in FIG. 6B, the radius of the semi-cylindrical portion  40 R is set at R 1 , while the distance between the center of the intermediate portion  32  and the round corner  40   b  is set at R 2 . The length R 1  is smaller than the length R 2  (R 1 &lt;R 2 ).  
         [0052]    In cooperation with the ribs  18  formed on the partition wall  14 , the stopper  40  prevents the movable member  20  from swiveling about the protrusion  30  through more than the maximum angle. Specifically, as shown in FIG. 6A, the rib  18   a  on the left is spaced from the center of the base portion  31  by a distance D 1 , while the other rib  18   b  on the right is spaced from the center of the base portion  31  by a distance D 2 . The distance D 1  is greater than the distance D 2  (D 1 &gt;D 2 ). The length or radius R 1  of the semi-cylindrical portion  40 R is equal to or slightly smaller than the distance D 2  (D1&gt;D2≧R1). The length R 2  of the rectangular portion  40 L is rendered greater than the distance D 1  (R 2 &gt;D 1 &gt;D 2 ≧R1).  
         [0053]    With such an arrangement, when the movable member  20  is caused to swivel relative to the base  10 , the semi-cylindrical portion  40 R of the stopper  40  does not come into abutment with any of the right and the left ribs  18   a,    18   b.  On the other hand, the round corners  40   b  of the rectangular portion  40 L of the stopper  40  will come into abutment with the right rib  18   b  (but not with the left rib  18   a ) in swiveling the movable member  20  relative to the base  10 . In this manner, the stopper  40  prevents the movable member  20  from being rotated about the protrusion  30  endlessly. In the illustrated embodiment, the stopper  40  (and hence the movable member  20 ) can be rotated through a maximum of 180 degrees.  
         [0054]    As being moved along the guide groove  16 , the axis of the protrusion  30  of the movable member  20  varies in inclination. For instance, when the protrusion  30  of the movable member  20  takes the lowermost position shown in FIG. 3, the rotation axis Ax extends upright, so that the non-illustrate CRT mounted on the movable member  20  is caused to swivel in the horizontal plane. However, when the movable member  20  is shifted to the left relative to the base  10  and takes a different position indicated by broken lines, the rotation axis Ax is not upright but slightly inclined. In this position, the non-illustrate CRT is caused to swivel in a non-horizontal plane.  
         [0055]    Referring to FIG. 7, according to the above-illustrated embodiment, the movable member  20  is readily assembled into the base  10  simply by pressing the protrusion  30  of the movable member  20  into the guide groove  16  of the base  10 . At this time, the flexible arms  33   a,    33   b  will give no unduly large resisting force to the partition wall  14 . Once the protrusion  30  is properly inserted into the guide groove  16 , with the arms  33   a,    33   b  having gone through the groove  16 , the once-closed arms  33   a,    33   b  are restored to the normal state, as shown in FIG. 4. As a result, the movable member  20  is anchored to the base  10 , while it still can tilt or rotate relative to the base  10 .  
         [0056]    Reference is now made to FIGS. 8 and 9 illustrating a tilt-swivel stand according to a second embodiment of the present invention. As in the first embodiment described above, the tilt-swivel stand of the second embodiment includes a base  10 ′ and a movable member  20 ′ slidably mounted on the base  10 ′. The base  10 ′ is provided with a leg portion  11 ′ and reinforcing ribs  15 ′. The convex lower surface  22 ′ of the movable member  20 ′ and the concave upper surface  12 ′ of the base  10 ′ are both configured to partially coincide with the surface of a sphere S′. Thus, the lower surface  22 ′ comes into snug engagement with the upper surface  12 ′.  
         [0057]    Differing from the first embodiment, a protrusion  30 ′ is provided on the side of the base  10 ′, while a guide groove  16 ′ cooperating with the protrusion  30 ′ is provided on the side of the movable member  20 ′.  
         [0058]    However, the arrangements of the protrusion  30 ′ itself are identical to those of the first embodiment. For instance, the protrusion  30 ′ is divided into a diametrically larger base portion  31 ′, a diametrically smaller intermediate portion  32 ′ and an end portion  33 ′ which is provided with a pair of flexible anchoring arms  33   a′  and  33   b′.    
         [0059]    Further, the relation between the protrusion  30 ′ and the guide groove  16 ′ is also the same as that of the first embodiment. For instance, the width of the guide groove  16 ′ is substantially equal to or slightly greater than the diameter of the base portion  31 ′ of the protrusion  30 ′. The flexible arms  33   a′  and  33   b′  are readily pressed into the groove  16 ′. Once properly put in place, the anchoring arms  33   a′  and  33   b′  serve to prevent the movable member  20 ′ from accidentally coming off the base  10 ′, while also allowing the movable member  20 ′ to tilt and swivel relative to the base  10 ′.  
         [0060]    The base  10 ′ is formed with a stopper  40 ′ adjacent to the base portion  31 ′ of the protrusion  30 ′, while the movable member  20 ′ is formed with parallel ribs  18 ′ cooperating with the stopper  40 ′ of the base  10 ′. As in the first embodiment, the stopper  40 ′ is brought into abutment with (either one of) the ribs  18  to prevent the movable member  20 ′ from being rotated too much relative to the base  10 ′.  
         [0061]    According to the second embodiment, the protrusion  30 ′ is provided on the stationary base  10 ′. This means that, differing from the first embodiment (see FIG. 3), the rotation axis of the movable member  20 ′ does not vary in inclination as the movable member  20 ′ is being tilted relative to the base  10 ′. Thus, the swiveling of the movable member  20 ′ takes place in the same plane.  
         [0062]    The present invention is not limited to the two embodiments described above. For instance, the tilt-swivel stand of the present invention can be used for supporting an object other than a CRT. Further, the configuration of the anchoring arms for attaching the movable member to the base is not limited to the illustrated example. The anchoring arms can be made into many forms as long as they facilitate the attachment of the movable member to the base and prevent the movable member from accidentally coming off the base.  
         [0063]    The present invention being thus described, it is obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention, and all such modifications as would be obvious to those skilled in the art are intended to be included within the scope of the following claims.