Abstract:
A system and method for automatically replacing a tray in a handler system is disclosed. The system and method includes a stacker assembly for housing a plurality of trays, each tray holding at least one device, and a replacement apparatus for automatically replacing a tray in the stacker assembly with a replacement tray. The system and method further includes identifying a tray in need of replacement, adjusting the stacker assembly so that the tray in need of replacement is aligned with the tray replacement apparatus, and replacing the tray with the replacement tray.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to handler systems, and more particularly to a handler system which incorporates a semi-automatic tray replacement apparatus.  
         BACKGROUND OF THE INVENTION  
         [0002]    With advances in technology, manufacturing and testing functions have become highly automated processes, requiring little human supervision or intervention. In the testing environment, systems have been developed that can automatically select a device to be tested, pass it though any type of pretest preparation, test the device, gather and store the test results, and then pass the device to a holding area for further processing. In the past, some, if not all, of these steps were performed by an operator. Today, however, the entire process can function largely without human intervention.  
           [0003]    After a device has been tested, it must be handled or stored in some manner so that the operator can differentiate between devices by type or testing results. In the area of integrated circuit testing, the devices are placed in trays after testing. Typically, the trays are organized to store particular types of devices. For example, one tray might be dedicated to a specific sort or bin category of a device. A handler system is an automated system that receives the tested device and places it in the appropriate tray according to its sort/bin category.  
           [0004]    [0004]FIG. 1 illustrates a typical handler system  10 , such as a Seiko Epson NS-5000, that operates in conjunction with a testing system (not shown). As is shown, the handler system  10 , includes a stacker assembly  15  containing a plurality of slots  20   a - 20   h  for receiving an equal number of trays  30   a - 30   h.  The slots  20   a - 20   h  are arranged vertically, one on top of the other, such that the trays  30   a - 30   h  are stacked. Each tray  30   a - 30   h  accommodates several devices  40  and is dedicated to a particular sort/bin category. In operation, the testing system (not shown) indicates which sort/bin category tray  30   a - 30   h  is needed. A servomotor  50  in the handler system  10  moves the stacker assembly  15  vertically (Y-Axis movement) so that the slot  20   e  containing the appropriate tray  30   e  is aligned to a stationary output platform  60 . The tray  30   e  is then placed on the output platform  60 , where a pickup head  70  places the tested device  40  in the tray  30   e.  The tray  30   e  is then returned to its corresponding slot  20   e , and the handler system  10  is ready to load another device  40 .  
           [0005]    When any tray  30   a - 30   h  is fully loaded with devices  40 , the servomotor  50  moves the stacker assembly  15  to a home position. Once there, the handler system  10  stops operation and sounds an alarm, informing the operator that a particular tray, e.g., tray  30   e  is full and needs to be replaced. In response to the alarm, the operator must manually remove the fully loaded tray  30   e , and replace it with an empty tray  30   e &#39; in the corresponding slot  20   e.  Thereafter, the operator must reset the handler system  10  to resume operation.  
           [0006]    Once the alarm is sounded, the handler system  10  will cease operation, and will not restart until the full tray  30 e has been replaced by the operator. In turn, the entire testing process upstream from the handler system  10  must stop because there is no where to place the devices  40  after they have been tested. If the operator is not present, the entire testing system will sit idle until the operator returns. Even if the operator is present to respond immediately to the alarm, it typically takes at least 30 seconds to exchange the tray  30   e  and to resume operation.  
           [0007]    Thus, under the absolute best circumstances, testing will stop for approximately 30 seconds. Nevertheless, under the worst circumstances, down time can extend for hours. In any event, any down time adversely effects efficiency and productivity, the two qualities supposedly optimized by automated systems.  
           [0008]    Accordingly, what is needed is a system and method for tray-replacement in an automated handler system, which minimizes workflow interruptions, and reduces the testing system down time. The system and method should provide for fast, efficient tray loading and unloading, and tray-exchange in an automated handler system. Further, the system and method should be cost effective and easy to implement with existing processes and equipment. The present invention addresses such a need.  
         SUMMARY OF THE INVENTION  
         [0009]    A system and method for automatically replacing a tray in a handler system is disclosed. The system and method includes a stacker assembly for housing a plurality of trays, each tray holding at least one device, and a replacement apparatus for automatically replacing a tray in the stacker assembly with a replacement tray. The system and method further includes identifying a tray in need of replacement, adjusting the stacker assembly so that the tray in need of replacement is aligned with the tray replacement apparatus, and replacing the tray with the replacement tray.  
           [0010]    The system and method in accordance with the present invention overcomes the problems of conventional handler systems by providing the capability of replacing a tray without necessarily stopping the operation of the handler system. Hence, the time and cost incurred due to work stoppages is avoided. Additionally, the tray replacement apparatus allows the tray-exchange procedure to occur automatically and allows the handler system to resume operation without the immediate attention of the operator, thereby enhancing productivity. The system and method in accordance with the present invention increases overall operating speed, improves efficiency, and reduces the cost of manufacturing. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 illustrates a side view of a conventional handler system.  
         [0012]    [0012]FIG. 2 illustrates a side view of the handler system incorporating the tray replacement apparatus in accordance with the present invention.  
         [0013]    [0013]FIG. 3 illustrates a back view of the tray replacement apparatus in accordance with the present invention.  
         [0014]    [0014]FIG. 4 illustrates the activated and deactivated states of a cylinder mounted on the housing bracket in accordance with one embodiment of the present invention.  
         [0015]    [0015]FIG. 5 is a flow chart illustrating the process of replacing the tray in accordance with the present invention.  
         [0016]    FIGS.  6 A- 6 C illustrates the tray exchange in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0017]    The present invention relates generally to handler systems, and more particularly to a handler system for integrated devices incorporating a tray replacement apparatus. The following description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements. Various modifications to the preferred embodiment and the generic principles and features described herein will be readily apparent to those skilled in the art. Thus, the present invention is not intended to be limited to the embodiment shown but is to be accorded the widest scope consistent with the principles and features described herein.  
         [0018]    The handler system in accordance with the present invention incorporates a tray replacement apparatus, which automatically unloads a tray from the stacker assembly to an unload area, and automatically reloads a replacement tray into the same slot. Once the replacement tray is in place, the handler system can resume its normal operation. The unloaded tray on the unload area can be retrieved by an operator at a later time without interrupting the handler system&#39;s operation.  
         [0019]    Although the present invention will be described in the context of a handler system with a stacker assembly and trays, such as Seiko Epson Model NS-5000 pick-and-place handler, one of ordinary skill in the art will appreciate that the principles described herein could apply to many types of material handling and assembly systems, and the replacement apparatus could be utilized effectively with holding units other than trays. Such use would be within the spirit and scope of the present invention.  
         [0020]    [0020]FIG. 2 illustrates a side view of the handler system  100  incorporating the tray replacement apparatus  110  in accordance with an embodiment of the present invention. Features similar in handler system  10  are denoted by similar numbers. The tray replacement apparatus (“TRA”)  110  is integrated internally into the handler system  100  and mounted within the system&#39;s  100  metal housing (not shown). The TRA  110  is preferably mounted beneath the output platform  60 , as shown in FIG. 2.  
         [0021]    The TRA  110  includes a driving system comprising a DC motor  112  connected to a belt and pulley arrangement  114 . An unload area  116  and load area  118  are stationary platforms with respective front ends  116   a  and  118   a,  the platforms being oriented in such a manner as to face the stacker assembly  15  and its slots  20   a - 20   h.  The TRA  110  also includes a linear bearing track  120  which runs alongside the stacker assembly  15 , from a back end of the slots  15   a  to the front ends  116   a,    118   a  of the unload and load platforms, respectively. A housing bracket  124  moves along the linear bearing track  120  via linear bearing blocks  122  which are mounted onto the housing bracket  124  and straddle the linear bearing track  120 . A pair of miniature cylinders, an upper cylinder 126  and a lower cylinder 128 , are mounted on a surface of the housing bracket  124  facing the tray  30   h.    
         [0022]    As is shown, the belt and pulley arrangement  114  runs parallel to the linear bearing track  120 . The linear bearing blocks  122  are in physical contact with the belt  114   a.  Thus, the linear bearing blocks  122 , and therefore the housing bracket  124 , move along the linear bearing track  120  when the belt  114   a  to moves longitudinally, which occurs when the DC motor  112  rotates. If the DC motor  112  rotates in a counter clockwise fashion, the belt  114   a  will move from left to right, thereby causing the housing bracket  124  to move from left to right. The opposite occurs, i.e., the housing bracket  124  moves from left to right, when the DC motor  112  rotates in a clockwise fashion.  
         [0023]    Referring now to FIG. 3, illustrated is a back view of the TRA  110  looking down the linear bearing track  120  from the slots&#39; back end  15   a  to the fronts of the platforms  116   a,    118   a.  As is seen, TRA  110  is situated such that the upper and lower cylinders  126 ,  128  are aligned with a tray  30   h  in the unload area  116  and a tray  30   h′  in the load area  118 , respectively. An important feature of the cylinders  126 ,  128  is the ability to extend and retract.  
         [0024]    [0024]FIG. 4 illustrates this feature which allows the TRA  110  to move a tray  30   h  to the unload area  116  and a tray  30   h′  from the load area  118 . The upper cylinder  126  is shown in FIGS. 4A and 4B. The upper cylinder  126  extends when activated in FIG. 4A, and retracts when deactivated in FIG. 4B. The lower cylinder  128  (not shown) exhibits the same functionality. This feature can be implemented by an electrical solenoid air valve (not shown) connected in parallel to the DC motor  112 , as is understood by one skilled in the art. In operation, the upper cylinder  126  is preferably located near the upper back corner of the housing bracket  124  (see FIG. 2), while the lower cylinder  128  is preferably located near the bottom front corner of the housing bracket  124 .  
         [0025]    When the housing bracket  124  is in a first position to unload the tray  30   h  from its slot  20   h,  the upper cylinder  126  is behind the tray  30   h,  as shown in FIG. 2. When the housing bracket  124  is in the first position, the upper cylinder  126  is activated so that the cylinder  126  engages the tray  30   h.  Thus, the housing bracket  124  can unload the tray  30   h  out of its slot  20   h  via the extended upper cylinder  126 .  
         [0026]    When the housing bracket  124  is in a second position to load a replacement tray  30   h′  into its slot  20   h,  the lower cylinder  128  is in front of the replacement tray  30   h′.  When the housing bracket  124  is in the second position, the lower cylinder  128  is activated so that the lower cylinder  128  engages the replacement tray  30   h′.  Thus, the housing bracket  124  can load the replacement tray  30   h′  into its slot  20   h  via the extended lower cylinder  128 .  
         [0027]    [0027]FIGS. 5 and 6 illustrate the tray replacement process in accordance with one embodiment of the present invention. The process  200  illustrated in FIG. 5 starts at step  210  when the handler system  100  senses that a tray  30  needs to be replaced, e.g., the tray  30  is full. In FIG. 6A, tray  30   e  is full and in need of replacement. The handler system  100  directs the stacker assembly  15  to move so that the tray  30   e  is aligned with the unload area  116 , via step  220 . Once aligned, in step  230 , the handler system  100  ensures that the upper and lower cylinders  126 ,  128  are deactivated, and then moves the housing bracket  124  to the first position alongside the tray  30   e  via the DC motor  112  and belt and pulley arrangement  114 .  
         [0028]    Next, the upper cylinder  126  is activated such that it extends behind the tray  30   e,  via step  240 . The DC motor  112  then moves the tray  30   e  forward, via the housing bracket  124  and upper cylinder  126 , onto the unload area  116 , and an alarm is sounded to alert the operator to remove the tray  30   e,  in step  250 . FIGS. 6A and 6B illustrate how the TRA  110  moves the tray  30   e  from the stacker assembly  15  to the unload area  116 .  
         [0029]    As is seen in FIG. 6B, the housing bracket  124  is in the second position when the tray  30   e  is completely on the unload area  116 . Referring back to FIG. 5, in step  260 , the stacker assembly  15  moves to align the now empty slot  20   e  with the load area  118 , which holds a replacement tray  30   e′.  The upper cylinder  126  is deactivated and the lower cylinder  128  is activated such that it extends in front of the replacement tray  30   e′,  via step  270 . Next, in step  280 , the DC motor moves the housing bracket  124  to the first position, thereby moving the replacement tray  30   e′  from the load area  118  into the slot  20   e  in the stacker assembly  15 . FIG. 6C illustrates this step. Once the replacement tray  30   e′  is in place, the lower cylinder  128  is deactivated in step  290 , and the handler system  110  returns to normal operation, via step  300 .  
         [0030]    As stated above, each tray  30   a - 30   h  is dedicated to a sort/bin category of the device  40 . Thus, when a tray  30  requires replacement, e.g. it becomes full, the handler system  100  of the present invention must inform the operator as to which sort/bin category the tray  30  belongs. One embodiment of the present invention accomplishes this by utilizing a display  130  (FIG. 2) linked to the TRA  110  which indicates the last bin/sort category before the handler system  100  sensed the need for tray replacement. The display  130  can be a multi-segment LED, or any other appropriate display such as an output on a computer screen. In this embodiment, it is assumed that the last device  40  placed in the tray  30  triggers the tray replacement process  200 .  
         [0031]    So for example, a device  40  is tested, the testing system informs the handler system  100  of the sort/bin category, the handler system  100  aligns the tray  30  corresponding to the device&#39;s sort/bin category with, and moves it onto, the output platform  60 , where the device  40  is placed in the tray  30 . If the tray  30  becomes full, the handler system  100  will begin the tray replacement process  200 . The sort/bin category of the device  40 , which was the last device  40  to be loaded, is transferred to the display  130 . Hence, when the operator comes shortly thereafter to remove the tray  30 , the operator will know to what sort/bin category the tray  30  belongs. Once the tray  30  is removed, the display  130  resets and the alarm mutes.  
         [0032]    With the handler system  100  in accordance with the present invention, the task of replacing trays  30  is transformed from a manual operation to a semi-automatic task. Thus, operator intervention is minimal, and more importantly, because the handler system  100  resumes operation automatically after replacing the tray  30 , system down time is minimized. The operator is only required to remove the tray  30  from the unload area  116 , and replenish the load area  118  with another replacement tray  30 &#39;. Accordingly, the present invention improves throughput, productivity, and system efficiency, while decreasing manufacturing costs and wasted time.  
         [0033]    Although the present invention has been described in accordance with the embodiments shown, one of ordinary skill in the art will readily recognize that there could be variations to the embodiments and those variations would be within the spirit and scope of the present invention. Accordingly, many modifications may be made by one or ordinary skill in the art without departing from the spirit and scope of the appended claims.