Abstract:
The invention concerns a tray having an integral latch that mates to a boss of an adjacent tray to form a stable stack. The latch may be incorporated into any type of tray, basket, or other container for storing articles. Multiple containers may be stacked together without the use of a detachable clip. Also disclosed is a tray that includes an array of posts extending downward to support the tray on a flat surface.

Description:
BACKGROUND OF THE INVENTION 
     FIG. 1A  illustrates a conventional tray  100  for transporting disk drive components. Tray  100  can be assembled into a stack by attaching a clip onto protrusion  20  and lip  13 . Such a clip  15  is shown in  FIG. 1B . To properly secure the stack  30  of  FIG. 1B , it is necessary to attach clip  15  to both sides of the stack. The disadvantages of a separate clip is that it can be easily misplaced and it has a limited stacking capacity. Only four trays can be secured in a stack with the prior art clip  15 . Clip  15  has a fixed height. Consequently, the number of trays that can be secured in a stack is always limited to the parameters of clip  15 . A need therefore exists for securing a stack of trays without having to use detachable clips. 
   SUMMARY OF THE INVENTION 
   The invention pertains to a tray having an integral latch for securing multiple trays in a stack. The latch is molded into the tray and permits multiple trays to mate together without using a separate detachable clip. 
   The present invention also pertains to a method of stacking two or more trays. In this embodiment, a first tray is aligned to the top of a second tray and the latch from one tray is moved toward the boss of the second tray. Thereafter the first tray is secured to the second tray by interlocking the latches of a first tray to bosses of a second tray. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  illustrates a tray with a boss for attachment to a clip in accordance with the prior art; 
       FIG. 1B  illustrates a stack of trays secured with a clip in accordance with the prior art; 
       FIG. 2A  illustrates a perspective view of a tray having an integral latch in accordance with the invention. 
       FIG. 2B  illustrates an exploded view of the latch head. 
       FIG. 2C  illustrates an exploded view of the boss portion of the latch. 
       FIG. 3  illustrates the principal angles associated with the latch; 
       FIG. 4A  is a sectional view of the tray stack illustrates a stack assembled in accordance with the present invention; 
       FIG. 4B  is a sectional view of the tray stack of  FIG. 4A . 
       FIG. 5A  illustrates a stack assembled in accordance with a second embodiment of the present invention; 
       FIG. 5B  is a sectional view of the tray stack of  FIG. 5A . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The preferred embodiments of the present invention will now be described with reference to  FIGS. 2A-5B . Similar components are designated with the same reference numerals throughout the various figures. The specific details and parameters are provided herein to further the understanding of the invention. 
   A tray  200  in accordance with the invention is illustrated in  FIG. 2A  as including an integral latch  55 . Tray  200  preferably has a basket or box-like configuration that includes a base  25  and a wall structure  23  extending from the base at a predetermined draft angle. Wall structure  23  comprises a first and a second pair of walls  37 ,  39 . An axis of symmetry exists between each pair of walls. Consequently, each of the second pair of walls has identical structures as the other. In the embodiment of  FIG. 2A , boss  27  is shown on one surface of wall  37 , whereas latch  55  extends from a first pair of walls. In the embodiment of  FIG. 2A , latch  55  extends from the exterior of each wall  37 . 
     FIG. 2B  illustrates an enlarged view of latch  55 , which comprises a head  10  connected to an extension  12 . Tray  200  and latch  55  are molded from the same material. However, latch  55  is more flexible than the other portions of tray  200  because the snap side of the latch is unconstrained. In addition, latch  55  preferably curves slightly outward in one direction.  FIG. 2C  illustrates an enlarged view of boss  27 , facing inward, toward the storage area of the tray. 
   The principal angles associated with the integral latch are illustrated in  FIG. 3 . Latch head  10  is defined by edges  29 A and  29 B. Edges  29 A and  29 B are angled to facilitate mating with a second tray. In a preferred embodiment, the angle θ between edge  29 A and edge  29 B ranges from 30 to 60 degrees. In this embodiment, the latch comprises a cantilever snap that projects outward from tray  200 . The cantilever snap is preferably present on each of a first pair of walls (such as walls  33 A and  33 B). Cantilever snap is also coplanar with the exterior surfaces of walls  33 A and  33 B. The preferred draft angle α between wall surface  30  and the latch head  10  ranges from 178 degrees and 180 degrees as shown in  FIG. 3 . 
     FIGS. 4A and 4B  illustrate trays  200  and  225  in a tray assembly are designed to stack on top of each other. The perimeter of tops  33  and corner regions  53  have profiles that facilitate stacking. Each tray has a lip  40  on the perimeter that may support corner regions  53  of an adjacent tray when stacked together. Specifically, a lower portion of each corner region may be supported by a lip  40  of an adjacent tray in a stack of trays. Bosses  27  of tray  200  are shown in  FIG. 4A  on interior wall  22 A. In operation each latch  55  grips a boss of an adjacent tray to snap the trays together. When trays  200  and  225  are snapped together, it is not possible to simply lift tray  200  vertically away from  225  without applying a force. 
   To disassemble the stack of  FIG. 4B , an operator places one hand on tray  225  and exerts a pull force by gripping a portion of tray  200  with a second hand. In this manner, the pull force separates latches  55  of tray  200  from bosses  27  of tray  225 .  FIG. 4B  illustrates a sectional view of boss  27  snapped into latch  55 . In the most preferred embodiment, latch  55  is provided on a lower portion of each tray, and the boss is located on an interior upper wall surface. However, the location of the boss and the latch can be interchanged. In other words, in a less preferred embodiment, the latch may extend from an upper interior portion of the tray, and the boss can protrude from a lower exterior wall portion. 
   Tray  200  of  FIG. 4A  has a base that includes posts  28  extending perpendicular to the floor  19 . Ramps are retained between posts  28 . In addition, tray  200  has a plurality of openings on each pair of walls and on the base. Alternative embodiments of the invention encompass trays that have a different floor on the base.  FIG. 5A  illustrates a sectional view of an alternative tray assembly wherein the base includes posts  24  extending downward from floor  19 . Posts  24  allow any tray or tray assembly of the present invention to be placed on a flat surface. In this embodiment, latch  55  preferably is shorter than post  24 . Otherwise, tray assembly  300  will rock if the length of latch  55  exceeds the length of posts  24 .  FIG. 5A  also illustrates the interference fit  70  that results when trays  200  and  225  are interlocked together. An exploded view of the interference fit  70  is shown in  FIG. 5B . When α is 178°, the interference or overlap in section  70  is 0.20 mm. The interference decreases to 0.10 mm, when α is 180°. 
   The present invention is not limited to solely containers that include posts  28  or  24 , or both  28  and  24 . For example, the floor of base  25  may instead include slots, pockets, raised mounts, or any other configuration for transporting articles. Moreover, the floor may alternatively be planar. Yet another example of a tray which may include the latch of the present invention is described in the following U.S. application entitled “Retention Latch for Packaging Apparatus” filed by the same inventors on May 16, 2005, the disclosure of which is hereby incorporated by reference. It is also understood that the invention may be used in baskets, and other containers in addition to trays, that are suitable for handling a plurality of articles. 
   The types of components that can be stored in trays  200  include electronic devices, medical instruments, and other articles of manufacture. 
   An advantage of the present invention is that the number of trays that can be stacked is not limited to the parameters of a detachable clip. The present invention relies on a latch and boss that are molded into the trays. When it is desirable to assemble a group of trays together, each tray is easily connected into a stable stack by mating their respective bosses to the latches of an adjacent tray.