Abstract:
Described is a portable cradle which includes a removable planar surface, a base and a plurality of vertical support members removably coupled to the base and supporting the planar surface above the base. Each vertical support member includes a biasing member urging the planar member upward away from the base with a total biasing force applied to the planar member being selected based on property of materials to be supported on the planar surface so that a position of an upper surface of the supported materials remains substantially constant as a quantity of materials supported on the planar surface is changed.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to portable devices that facilitate dispensing of materials. More specifically, the present invention relates to portable cradle devices with a feed mechanism that dispense various materials.  
         BACKGROUND INFORMATION  
         [0002]    Many types of construction materials are used as slabs or sheets, that can be used directly as in the case of pre-shaped tiles and bricks, or can be finished and then used, as in the case of sheet rock, concrete slabs and the like. Typically, these materials are supplied to the work site in stacks, such that the sheets of material are placed one on top of the other, and possibly bound together, so that large numbers of the material elements may be moved at one time. When the materials are used, the stacks are moved near the location where they are needed, and the material elements are removed from the stack one by one.  
           [0003]    As the sheet like construction materials are removed from the stack, the height of the stack is reduced. Since the construction worker removes the materials from the top of the stack, the topmost element that is presented to the worker for removal is not in a fixed position. When the stack is first started, the element being presented may be at a great height, at the top of the original stack. When the stack is almost used up, the element being presented is low, near a surface where the stack has been deposited, such as on the ground.  
           [0004]    This method of stacking elements of construction materials is not satisfactory, because it forces the worker to reach up for the materials at first, and to reach further and further down as the stack of materials is used. This process is not efficient, because the worker has to constantly reach for the materials in a different location. The process may be also unsafe, because the worker at some times has to reach up and lower to a working height the possibly heavy materials, and at other times must lift the materials up from near the ground. Back injuries may ensue from repeatedly lifting the heavy construction elements, while the materials may be dropped when removed from the top of a high stack, causing possible injury to the worker or damage to the materials.  
           [0005]    The problem may be somewhat alleviated by using materials bound in smaller stacks, so that the distance between the top and bottom of the stack is not great. However, it is much more efficient to move the construction materials in larger stacks, so that fewer trips to the work location are necessary to complete the work. In particular, if fork lifts or other mechanized equipment is used to move the materials, the larger the stack that can be brought to individual workers, the more efficient the process becomes.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention relates to a portable cradle which includes a removable planar surface, a base and a plurality of vertical support members removably coupled to the base and supporting the planar surface above the base. Each vertical support member includes a biasing member urging the planar member upward away from the base with a total biasing force applied to the planar member being selected based on property of materials to be supported on the planar surface so that a position of an upper surface of the supported materials remains substantially constant as a quantity of materials supported on the planar surface is changed.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 a  shows a perspective view of an exemplary embodiment of the cradle according to the present invention;  
         [0008]    [0008]FIG. 1 b  shows another exemplary embodiment of the cradle according to the present invention;  
         [0009]    [0009]FIG. 2 a  shows a side elevation view of the embodiment shown in FIG. 1 a;    
         [0010]    [0010]FIG. 2 b  shows a side elevation view of the embodiment shown in FIG. 1 b;    
         [0011]    [0011]FIG. 3 a  shows a top plan view of the embodiment shown in FIG. 1 a;    
         [0012]    [0012]FIG. 3 b  shows a top plan view of the embodiment shown in FIG. 1 a  having female attaching members;  
         [0013]    [0013]FIG. 4 shows a sectional view on line IV-IV of FIGS. 2 a  and  2   b  of an embodiment of the support and spring structure;  
         [0014]    [0014]FIG. 5 shows a sectional view on line V-V of FIGS. 2 a  and  2   b  of an embodiment of the connection between a support structure and a planar surface;  
         [0015]    [0015]FIG. 6 shows a perspective view showing a detail of mounting blocks on a base according to an embodiment of the present invention;  
         [0016]    [0016]FIG. 7 shows a top view showing a first storage configuration of the cradle according to the present invention; and  
         [0017]    [0017]FIG. 8 shows a top view showing a second storage configuration of the cradle according to the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0018]    The present invention may be further understood with reference to the following description and the appended drawings, wherein like elements are referred to with the same reference numerals.  
         [0019]    The cradle according to embodiments of the present invention may be utilized to hold stacks of materials (e.g., sheet-like construction materials) near the point of use of those materials. The exemplary cradle presents a topmost one of the elements in the stack at a substantially constant height, so that the worker using the materials can reach for the materials at a nearly constant, convenient height above the ground. The worker does not have to reach up to take the elements when the stack is full, and does not have to bend over to pick up the material elements when the stack is nearly used up. Thus, the worker may incur fewer injuries due to lifting and may work in a more efficient manner. Large stacks can be used, while the top most element in the stack is always presented at a convenient location.  
         [0020]    [0020]FIG. 1 a  shows an exemplary embodiment of the cradle according to the present invention. Cradle  100  includes a base  102  that provides an anchoring point on the ground for the rest of the cradle  100 . A support mechanism  109  is provided to position planar surface  106  relative to the base  102 . Planar surface  106  receives the materials  200  (e.g., construction materials), and is movable in the direction shown by arrows “A” with respect to base  102 . Support mechanism  109  provides a guide to control the movement of planar surface  106 , so that it can move only in a direction substantially perpendicular to base  102 . A system to resist displacement of planar surface  102  from a preferred distance “d” from base  102  is also provided by support mechanism  109 . This system applies a restoring force to planar surface  106 , that opposes the weight of construction elements  200  deposited on the planar surface  106 .  
         [0021]    In the exemplary embodiment shown in FIG. 1 a , the support mechanism  109  includes several support members  104  that are secured to base  102 , and extend substantially perpendicularly therefrom. Supports  104  and base  102  form a structural frame for cradle  100 . For example, for a rectangular base  102 , there may be four supports  104  placed at the corners of base  102 . Alternatively, a different shape of the base  102  or planar surface  106  may require a different configuration of supports  104 . Supports  104  may include guides  108  that are designed to direct the movement of planar surface  106  in a desired direction. Guides  108  may have a shape complementary to corners  111 , to permit planar surface  106  to move in a direction along arrows “A”, substantially perpendicular to base  102 .  
         [0022]    [0022]FIG. 1 b  shows another exemplary embodiment of the cradle  100  according to the present invention which is similar to the embodiment shown in FIG. 1 a . The cradle  100  has a plurality (e.g., three or four) moving arrangements, such as wheels  230 ,  232 . The moving arrangements allows the worker easily move heavy loads of materials  200 . In addition, the moving arrangements may have a braking mechanism (not shown). The braking mechanism allows the worker to fix the cradle  100  at a particular location, thus preventing the cradle  100  from incidentally moving from that fixed location.  
         [0023]    Also, the material  200  may be a different shapes. For example, the material  200  may be a shape of the surface  106  (as shown in FIG. 2 a ). Alternately, the material  200  may be of a smaller shape and placed in the middle of the surface  106  (as shown in FIG. 1 a ). Those skilled in the art would understand that materials  200  may come in different shapes and sizes and that the cradle  100  may be adjusted to accommodate theses shapes and sizes. For example, to accommodate the smaller shape materials  200  (as a shown in FIG. 1 a ), a frame (not shown) may be attached to the surface  106  which would prevent the materials  200  from shifting.  
         [0024]    As shown in FIGS. 1 a ,  1   b ,  2   a  and  2   b , support mechanism  109  may also include resilient/biasing elements such as springs  110 , used to urge the planar surface  106  to a desired height “d” from base  102 . Springs  110  may be associated with the supports  104 , or alternatively may be separate. In the exemplary embodiment shown, there is a spring  110  for each support  104 . However, the number of springs  110  and supports  104  does not have to be the same. In the exemplary embodiment, springs  110  are located between the base  102  and planar surface  106 . The neutral extension of springs  110 , meaning the extension at which no force is exerted, corresponds to the desired height “d”. When a weight such as stack  200  is placed in planar surface  106 , springs  110  are compressed, and tend to resist the displacement of planar surface  106 . Since the resisting force exerted by a spring is proportional to its compression, the more planar surface  106  is displaced, the greater the force opposing such displacement is generated by springs  110 .  
         [0025]    By carefully selecting the size and spring constant of springs  110 , it is possible to control the displacement of planar surface  106  such that topmost element  202  on stack  200  will always be at or near the height “d” from base  102 . For example, when the cradle  100  is empty, the weight of planar surface  106  will balance the spring force at height “d”. When a full stack is added, the additional weight compresses springs  110  until topmost element  202  is approximately at a height “d”, while planar surface  106  is lower. As the elements of construction material are removed from the top of stack  200 , the reduced weight compresses springs  110  less, and planar surface  106  is pushed upwards, such that the new topmost element is now approximately at a height “d” above base  102 . It should be apparent to one skilled in the art that the same result may be obtained by using springs under tension rather than under compression, for example simply by connecting the springs to the tops of supports  104  rather than to base  102 . A feed mechanism for the construction elements is thus provided, that places the topmost element of the stack at a constant height.  
         [0026]    The exemplary embodiment shown provides the advantage that planar surface  106  is to a certain extent self leveling. Springs  110  are located at the corners, and if a weight is placed near a corner rather than near the center of planar surface  106 , the spring nearest to the weight will be compressed the most, causing a greater restoring force that opposes further compression of that spring. The corner where the weight was added thus drops only a small distance, before further displacement is stopped by the spring.  
         [0027]    Elements of the exemplary embodiment of the present invention are further described with reference to FIG. 4. A detail of the support mechanism  109  is shown, as a cross section view taken on line IV-IV of FIGS. 2 a  and  2   b . One of supports  104  is shown, in this example having a structural portion with an L shaped cross section which resists buckling, and provides stability to the structure. In this example, the four L shaped supports  104 , together with base  102 , form a rigid frame that keeps the movement of planar surface  106  constrained to the desired direction.  
         [0028]    The support mechanism  109  of the exemplary embodiment includes a spring guide  112  that may be attached to support member  104 . Spring guide  112  surrounds a portion of the perimeter of spring  110 , and thus prevents it from buckling or being displaced. In this exemplary embodiment, spring guide  112  forms an internal channel, but does not completely surround spring  110 , so that a connection with planar surface  106  may be made, as will be described below. However, other configurations of spring guide  112  may be devised, which may surround spring  110  to a greater or lesser extent. In the configuration shown in FIG. 4, spring guide  112  has a circular cross section that extends for slightly more than 180 degrees, so that spring  110  cannot fall out through the opening defined by edges  120 . In this configuration, spring  110  is not attached to spring guide  112 , and is retained by gravity within channel  122  defined by the guide  112 .  
         [0029]    Planar surface  106  may have extensions  114  that are shaped to fit in guides  108  of the support mechanism  109 . In the exemplary embodiment shown in FIG. 5, extension  114  is a track interface that fits in the track or channel  122  defined by spring guide  112 , which here also acts as a guide for planar surface  106 . However, different configurations may be designed where extension  114  fits in a separate guide, or is guided by the surfaces of support member  104 . In this exemplary embodiment, extension  114  is circular, and fits in channel  122  on top of spring  110 . Thus, the force exerted by spring  110  is transmitted to planar surface  106  through the extensions  114 , which have the dual role of interfacing with springs  110  and keeping the planar surface  106  within the guide portions. Extension  114  may enter channel  122 , for example, through the opening defined by edges  120 . The combination of forces applied to a plurality of extensions  114  by corresponding spring guides  112  maintains planar surface  106  in its proper position relative to base  102 , particularly if extensions  114  are spaced around the perimeter of planar surface  106 , as shown in FIG. 3.  
         [0030]    According to an exemplary embodiment of the present invention, the frame of cradle  100  is disassembled, so that when not in use the cradle  100  may be stored or transported easily. In the present embodiment, planar surface  106  may be lifted up away from support members  104 , since during use it rests by gravity on springs  110 , within spring guides  112 . Springs  110  also can be lifted out of spring guides  112 , which in turn are easily removable from support members  104 . Support members  104  may be removed from base  102 , since they are held in place thereon by a friction or locking mechanism. In an alternative embodiment, support members  104  may be hinged to base  102 , so that when not in use they may be folded within the base  102 .  
         [0031]    [0031]FIG. 6 shows an exemplary embodiment of the mounting blocks  152  for the support members  104  and springs  110  to base  102 . A single mounting block  152  may be used for both components, or separate attachments may be used. The mounting block  152  may be a solid cylindrical base having a shape, e.g., of a male pedestal. The support member  104  and the spring  110  may be removably coupled to the mounting block  152 .  
         [0032]    In alternative exemplary embodiment of the present invention, the support member  104  and the spring  110  may be attached to the base  102  using a female attaching members  240  shown in FIG. 3 a . Each of the female attaching members  240  is coupled on the exterior of the base  102  and has a shape of a female coupling. The support member  104  and the spring  110  are removably inserted into the female attaching member  240 . The guide  112  stops at the top of the base  102 , while the spring  110  extends through the base  102  and stops at the bottom of the base  102 . The female attaching members  240  also server buffers to prevent incidental damage to the cradle  100  if it collides with another object.  
         [0033]    As indicated above, cradle  100  may be folded when not in use. FIGS. 7 and 8 show successive steps to disassemble and fold the cradle  100 . In FIG. 7, the springs  110  and support members  104  are removed from mounting blocks  152  of base  102 , and are placed within a box like storage portion formed by bottom surface  150  and side surfaces  154  of base  102 . In a subsequent step illustrated in FIG. 8, the planar surface  106  is placed on top of the springs  110  and support members  104 , forming a lid to the box defined by base  102 . In another embodiment, latches or locks may be used to prevent separation of planar surface  106  from base  102 , so that the components of the support mechanism may be securely held in the box like structure. The entire cradle  100  can be transported between job sites, or may be stored while occupying a minimal amount of space.  
         [0034]    This dual nature of the cradle  100  is one of its main advantages. The cradle  100  may, on one hand, serve to support materials  200  at a certain height; on the another hand, the cradle  100 , when in the folded position, may server a dolly to move the materials  200 . Another advantage of the present invention is that the cradle  100  does not require any complicated electrical and/or mechanical components. Furthermore, the cradle  100  allows to load the materials  200  from the top.  
         [0035]    In the preceding specification, the present invention has been described with reference to specific exemplary embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broadest spirit and scope of the present invention as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative rather than restrictive sense.