Abstract:
A collapsible music stand including a ground engaging base portion, an upright portion, and a selectively collapsible desk portion. The desk has a pair of body portions operably coupled by a pair of over-center toggle linkages. Each over-center toggle linkage is selectively positionable in at least a first favored position, wherein the linkage is extended so that the body portions are spaced apart and the linkage opposes movement of the body portions toward each other. Further, the toggle linkages are positionable in a second favored position wherein the body portions are freely movable toward each other to collapse the desk. The desk further includes at least one resilient element arranged so as to bias the body portions toward each other when each the toggle linkages are positioned in the first favored position.

Description:
This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application Serial No. 60/361,674, filed Mar. 5, 2002, said application also being fully incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Music stands that are collapsible for ease of storage and handling are well known. One commonly used design has a music desk comprising stays or wires connected in a scissors arrangement, and attached to an upright base. An example of this type is found in U.S. Pat. No. 6,260,812 to Auke disclosing a collapsible music stand comprising a rod shaped central upright supported by legs and with a head consisting of extendable stays that can be folded. Stands of this type, however, typically lack rigidity in the desk assembly. As a result, they often do not provide adequate support for sheets of music, especially when the music is thin or is of a large size. Neither are they suitable for supporting heavy items such as books. 
     Another type of stand has a solid music desk comprised of folding platens, hinged together in any number of arrangements. An example of this type is found in U.S. Pat. No. 5,979,856 issued to Hsu. The folding platens of this type, however, generally make the stand heavy and bulky when folded. 
     Both types of prior art stands generally lack means for easily and securely adjusting tilt of the desk. Often, no adjustment at all for tilt is provided. If provided, the means used sometimes relies on friction between two parts to maintain a selected position. Such an arrangement is prone to undesired movement if bumped or even if a heavier object is placed on the desk. Other arrangements involve parts secured with a screw or bolt. Such arrangements, however, have the disadvantage of being hard to adjust and manipulate, and difficult to disassemble for storage or transport. 
     What is needed is a stand that is easily collapsible into a compact form, while having a rigid desk assembly when deployed. Such a stand should be capable of handling very large and thin music sheets as well as books and other heavy items at a variety of desk tilt angles. 
     SUMMARY OF THE INVENTION 
     The present invention is a collapsible music stand that addresses the problems found in the prior art. The stand generally includes a desk assembly, an upright assembly and a base. 
     In preferred embodiments, the desk is collapsible, and includes a lower music rest and a crown member connected at the sides by an arrangement of pivoted arms. When extended so that the desk is in a deployed condition with the music rest and crown member spaced apart, the arms are positioned in an “over-center” arrangement with the pivot of the arms displaced to one said of a center axis which extends through the ends of each arm. The arms are biased against arm stops on the music rest and the crown member by elastic or spring bias members that act to pull the top member towards the music rest. This arrangement provides a very rigid desk suitable for supporting heavy items. When desired, the desk can be collapsed by pressing the arms inward and pushing the top member toward the music rest. Recesses for the arms may be provided so that the desk folds into a compact package. 
     A quick-connect device may be provided so that the desk is easily and quickly detachable from the base and upright. Desk tilt is preferably user adjustable with a hand operable spring-loaded tilt adjustment apparatus having a number of discrete positions. Also, extensible clips may be provided to support large sheets of music or other matter. 
     The upright assembly may be height adjustable by means of telescoping members that are held in a desired position with a compression fitting. The telescoping members also allow the upright assembly to be collapsed into a compact form. 
     In preferred embodiments, the base assembly may include pivoted legs that are inwardly foldable. In use, the base assembly may be secured to the bottom of the upright assembly with a threaded connection. The base assembly can thus be unthreaded and the mounting hub slid along the upright assembly when the stand is collapsed. Thus, with legs folded, the base and upright assembly assume a compact, easily transportable and storable form. 
     Thus, a collapsible music stand according to the present invention includes a ground engaging base portion, an upright portion, and a selectively collapsible desk detachably operably coupled to the upright portion. The desk has a pair of body portions operably coupled by a pair of over-center toggle linkages. Each over-center toggle linkage is selectively positionable in at least a first favored position, wherein the linkage is extended so that the body portions are spaced apart and the linkage opposes movement of the body portions toward each other. Further, the toggle linkages are positionable in a second favored position wherein the body portions are freely movable toward each other to collapse the desk. The desk further includes at least one resilient element arranged so as to bias the body portions toward each other when each the toggle linkages are positioned in the first favored position. The music stand may also include a tilt mechanism enabling the desk to be selectively positioned at any of a plurality of predetermined discrete tilt positions. Extensible music clips may be included to enable the desk to support music pieces having extended width dimensions. 
     The present invention may also be characterized as including a music stand with a ground engaging base portion, an upright portion, and a selectively collapsible desk detachably operably coupled to the upright portion. The desk includes a pair of articulating arm assemblies, each having a pair of opposing ends and including a pair of links connected at a pivot, each arm assembly presenting a center axis extending through the ends. Further, the desk includes a pair of opposing body portions arranged so as to operably couple the pair of body portions. The body portions and the arm assemblies have cooperating stop structures defining a favored deployed position of the desk wherein the body portions are spaced apart and the pivot of each arm assembly is laterally displaced from the center axis in a first direction. The arm assemblies and the body portions are adapted so that when the pivot of each said arm assembly is laterally displaced from the center axis in a second direction opposite the first direction, the desk is positionable in a favored collapsed position wherein said arm assemblies are folded and the body portions are adjacent each other. At least one resilient element is provided coupling the body portions and arranged so as bias the desk in the deployed position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a music stand according to the present invention in a fully deployed position; 
     FIG. 2 is a frontal elevation view of the stand of FIG. 1; 
     FIG. 3 is a bottom plan view of the stand of FIG. 1; 
     FIG. 4 is a rear elevation view of the stand of FIG. 1; 
     FIG. 5 is a top plan view of the stand of FIG. 1; 
     FIG. 6 is a side elevation view of the stand of FIG. 1; 
     FIG. 7 is a front elevation view of the desk in a fully deployed position; 
     FIG. 8 is a front elevation view of the desk in a partially collapsed position; 
     FIG. 9 is a front elevation view of the desk in a fully collapsed position; 
     FIG. 10 is a view of the connection details of the base portion and upright portion of the stand; 
     FIG. 11 is a view of an extensible clip assembly according to the invention; 
     FIG. 12 is side elevation view of the stand depicting desk tilt angle adjustment; 
     FIG. 13 is an enlarged perspective view of the desk tilt adjustment assembly; 
     FIG. 14 is a cross-sectional view of the desk tilt adjustment assembly of FIG. 13; 
     FIG. 15 is an end elevation view of the desk tilt adjustment assembly; 
     FIG. 16 is a perspective view of the stand depicting the extensible clips supporting a piece of music; 
     FIG. 17 is a front elevation view of an alternative embodiment of a desk assembly according to the present invention; and 
     FIG. 18 is a partially exploded view of a compression fitting height adjustment for the upright assembly. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Collapsible music stand  20  generally includes a base portion  22 , an upright portion  24 , and a desk  26 . When collapsed, desk  26  may be detached from upright portion  24 , and base portion  22  may be positioned axially along upright portion  24  as depicted in FIG. 10, thus presenting compact components that can be easily moved and stored. 
     Base portion  22  generally includes a hub portion  28  and legs  30 . Hub portion  28  is generally cylindrical in shape and has a longitudinal bore  32 , a portion of which may be internally threaded. Leg mount tabs  34  project radially from hub portion  28 , each having an aperture  36  for receiving a pivot pin  38 . Each of legs  30  has a recess  40  for receiving one of leg mount tabs  34 . Bore  42  extends through leg  30  and is positioned so as to correspond with aperture  36  when the tab  34  is received in recess  40 . Pivot pin  38  extends through bore  42  and aperture  36  so that each leg  30  is pivotally attached to hub portion  28  at pivot pin  38 . The bottom peripheral corner  44  of leg  30  may be rounded as depicted in FIG. 10 to enable the pivoting movement. Also, the inner face  46  of leg  30  may be concave so as to fit conformingly with outer surface  48  of hub portion  28 . 
     Upright portion  24  generally includes an outer shaft portion  50 , an inner telescoping shaft portion  52 , a bottom cap  54  and a desk connector portion  56 . Bottom cap  54  fits on the bottom end  58  of outer shaft portion  50 , and may have a threaded portion  60  on the outer surface  62  thereof. Outer shaft portion  50  may be sized so as to slidably fit through longitudinal bore  32  of hub portion  28 , and be slidable thereon, as depicted in FIG.  10 . Threaded portion  60  may thread into the internal threads of longitudinal bore  32  so that base portion  22  may be secured to upright portion  24 . 
     Inner telescoping shaft portion  52  is axially slidable within an axially oriented bore  53  in outer shaft portion  50 . The axial position of inner telescoping shaft portion  52  can be fixed with respect to outer shaft portion  50  using height adjustment assembly  64  shown in FIG.  18 . Height adjustment assembly  64  generally includes a top cap  66  disposed over the top end  68  of outer shaft portion  50 , a ferrule  70 , and a compression sleeve  72 . 
     In operation, after inner telescoping shaft portion  52  is slidably positioned at a desired position within outer shaft portion  50 , ferrule  70 , which is interiorly threaded, is threaded onto threaded portion  74  of top cap  66 . As ferrule  70  is tightened, compression sleeve  72  is forced into the annular space  76  between inner telescoping shaft portion  52  and outer shaft portion  50 . The increased friction between inner telescoping shaft portion  52  and outer shaft portion  50  acts to resist relative axial sliding and to thus maintain the desired position. In a preferred embodiment, inner telescoping shaft portion  52  may be retained within outer shaft portion  50  by a friction sleeve (not depicted) inserted in groove  78  and adapted to engage top cap  66  so as to prevent withdrawal of inner telescoping shaft portion  52 . It will of course be appreciated that any other suitable arrangement could also be used to retain inner telescoping shaft portion  52 , including a flared end. 
     Desk  26  generally includes a first body portion  80  which may be a music rest  82 , a second body portion  84  which may be a crown member  86 , a pair of articulating arm assemblies  88  in the form of over-center toggle linkages  90 , and resilient tension members  92 . Each articulating arm assembly  88  generally includes a pair of arm links  94 ,  96 , pivotally coupled at a pivot  98  forming a toggle linkage. Each articulating arm assembly  88  presents a center axis  100 , which extends through the opposing ends  102 ,  104  of the assembly  88 . 
     Music rest  82  generally includes a back portion  106  and a tray portion  108 . Tray portion  108  projects generally perpendicularly from front side  110  of back portion  106  proximate bottom edge  112 . One or more longitudinal grooves  114  may be provided on tray portion  108  to retain the bottom edge of music, as well as pencils, batons or other items. Front side  110  of back portion  106  further has a recessed region  116  formed therein for receiving arm links  96  when folded as will be explained in further detail hereinbelow. Recessed region  116  is defined by a perpendicular surface  120 . 
     Crown member  86  generally includes a main portion  122  and an arcuate handle portion  124 . Main portion  122  has a pair of recessed regions  126 , defined by perpendicular surfaces  128 , for receiving arm links  94  when folded. Arcuate handle portion  124  is attached to main portion  122  above cutout  130 . 
     Each arm link  94  is pivotally coupled to crown member  86  in one of recessed regions  126  at an upper pivot  132 , and each arm link  96  is pivotally attached to music rest  82  in recessed region  116  at a lower pivot  134 . When desk  26  is in a first favored deployed position as depicted in FIG. 7, edge  136  of arm link  96  engages arm stop portion  138  of perpendicular surface  120 , and edge  140  of arm link  94  engages arm stop portion  142  of perpendicular surface  128 . Arm links  94 ,  96 , are thereby prevented from any further outward lateral rotational movement about upper pivot  132  and lower pivot  134  respectively. Also, when edge  136  is engaged with arm stop portion  138  and edge  140  is engaged arm stop portion  142 , pivot  98  is disposed laterally outboard from center axis  100  by a distance annotated D 1  in the drawings, being thus disposed slightly “over-center”. 
     One or more resilient tension members  92  are connected between music rest  82  and crown member  86  so as to exert a biasing force tending to pull music rest  82  and crown member  86  toward each other, as indicated by the arrow in FIG.  7 . The biasing force exerted by tension members  92  is resisted by the arm assemblies  88 . Since pivot  98  is disposed outwardly from center axis  100 , the biasing force has a horizontal component, annotated FY, acting to force pivot  98  outwardly and to force edges  136 ,  140 , into arm stop portions  138 ,  142 , respectively. In this deployed position, desk  26  has a stable, generally rectangular shape. 
     Tension members  92  are preferably elastic cords made from resilient material such as nylon. It will be readily appreciated that other elastic or spring biasing means that accomplish the purpose of providing a biasing force for drawing crown member  86  toward music rest  82  may be used according to the invention. For example, an arrangement of coil springs could be used. Another example could involve wire, string members, straps, or the like equipped with retractors for example, spring-loaded retractors, concealed or positioned in the music rest  82  or crown member  86 . 
     Desk  26  is depicted in a partially collapsed configuration in FIG. 8, and in a fully collapsed position in FIG.  9 . To collapse desk  26 , pivots  98  are pushed inward to the other side of center axis  100  as depicted in FIG. 8, thereby pivoting arm links  94 ,  96 , about upper and lower pivots  132 ,  134 , respectively, and away from arm stop portions  138 ,  142 . Arm links  94 ,  96 , pivot inward into recessed regions  116 ,  126 , until edges  144 ,  146 , are proximate perpendicular surfaces  120 ,  128 , and crown member  86  is proximate or even contacting music rest  82  as depicted in FIG.  9 . Tension members  92  fold in on themselves, or alternatively, could be provided with a retraction mechanism (not depicted) to take up any slack. 
     In addition to the embodiment depicted here, it will be appreciated that a variety of alternative arrangements of cooperating structures are possible on arm assemblies  88  and first and second body portions  80 ,  84 , to position the desk components in the favored deployed position. For example, suitable structures on the arm assemblies  88  adapted and positioned to engage with portions of body portions  80 ,  84 , could be substituted for the arm stop portions  138 ,  142  on body portions  80 ,  84 . 
     Desk  26  may be detachably coupled to upright portion  24  by any suitable method or mechanism. In a preferred embodiment, depicted in FIG. 13, a standard female quick-connect air hose connector fitting  148  is affixed to the upper end  150  of inner telescoping shaft portion  52  of upright portion  24 . A cooperating male fitting  152  of the air hose connector is affixed to desk  26  and is arranged to face downwardly. Desk portion  26  may thereby be attached and detached from upright portion  24  by engaging and disengaging male fitting  152  from female fitting  148 . 
     Music stand  20  may include a desk tilt adjustment assembly  154  for providing a tilt adjustment of desk  26  about a horizontal axis, annotated x—x in the drawings. Tilt adjustment assembly  154  generally includes an outer, hollow portion  156  and an inner portion  158 . Inner portion  158  is axially slidable within outer portion  156 , and has a portion  160  with a generally square cross-section. Outer portion  156  has a proximal portion  162  with a plurality of inwardly directed notches  164 , which are adapted to engage the shoulders  166  of portion  160 . It will be appreciated that, when inner portion  158  is axially positioned in a first position so that shoulders  166  are engaged with notches  164 , outer and inner portions  156 ,  158 , are rotationally fixed together. It will be appreciated that notches  164  define discrete rotational positions for inner portion  158  within outer portion  156 . When inner portion  158  is axially positioned in the direction of the arrows as depicted in FIG. 14 in a second position wherein portion  160  is within distal portion  168  of outer portion  156 , inner portion  158  is freely rotatable therein. A compression spring  170  may be provided to bias inner portion  158  toward the first position. As will be readily appreciated, any other suitable arrangement, such as a solid piece of resilient material, may be used in place of compression spring  170 . 
     In the preferred embodiment depicted in FIG. 13, outer portion  156  is connected to mounting plate  172 , which in turn is attached to desk  26  with fasteners  174 . Male fitting  152  projects from inner portion  158  through an aperture  176  in outer portion  156  and is received in female connector fitting  148  of upright portion  24  as previously described. A button  178  may be provided on inner portion  158  to enable axial positioning of inner portion  158  by a user. 
     The operation of desk tilt adjustment assembly  154  may now be understood by reference to FIGS. 12-15. When disposed in the first position described above, inner portion  158  is rotationally fixed to outer portion  156 , thereby fixing desk  26  at a tilt angle, annotated α in the drawings. When button  178  is depressed, inner portion  158  slides axially inward, disengaging shoulders  166  from notches  164 . In this position, inner portion  158  is rotatable within outer portion  156 , enabling desk  26  to be tilted to any desired tilt angle α within the rotational range of travel of the mechanism. Once desk  26  is positioned at the desired angle, compression spring  170  returns inner portion  158  to the first position with shoulders  166  engaging notches  164 , thereby fixing desk  26  at the desired angle. 
     It will of course be appreciated that numerous variations of desk tilt adjustment assembly  154  are possible. For example, the number of discrete tilt positions provided by the mechanism may be varied, depending on the number and spacing of notches  164 . Also, the position of the cooperating structures could be reversed, with notches  164  being on inner member  158  and a suitable engaging structure on outer member  156 . In addition, the orientation of the desk tilt adjustment assembly itself could be reversed so that desk  26  is connected to inner portion  158  and upright member  24  is connected with outer portion  156 . 
     The music stand  20  of the present invention may also be provided with one or more extensible music clips  180  as depicted in FIGS. 11 and 16 for holding large width sheet music pieces  190  that may extend beyond the lateral margins  182  of desk portion  26 . Each music clip  180  generally includes a telescoping rod portion  184  and a paper clip  186 . Music clip  180  may be arranged so as to retract within a recess  188  provided for the purpose in crown member  86 . 
     In operation, music clip  180  may be pulled laterally outward by a user to extend telescoping rod portion  184 , thereby positioning paper clip  186  at a suitable position for supporting an extra width piece of sheet music  190  as depicted in FIG.  16 . 
     In addition to the embodiments depicted in FIGS. 1-16, it will be recognized that other arrangement of the over-center articulating arm sets  88  and body portions  80 ,  84 , of desk portion  26  are possible. For example, as depicted in FIG. 17, the arm sets  88  may be disposed at the top and bottom of the desk  26 , while body portions  80 ,  84  are laterally opposed.