Abstract:
In a horizontal conveyance type auto-handler, the operation of a carrier is stopped when a positional displacement of the carrier relative to a test board is detected. A shaft is provided on a center of a guide pin on the test board. When the carrier which is displaced relative to the test board is lowered, the shaft is pushed down by the carrier, and the lowering of the shaft is detected by an optical sensor, thereby stopping the lowering operation of the carrier.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention:  
           [0002]    The invention relates to a carrier positional displacement detecting mechanism which is suitable for positioning a carrier relative to a test board on which IC sockets are disposed in a horizontal conveyance type auto-handler.  
           [0003]    2. Description of the Prior Art:  
           [0004]    There is a horizontal conveyance type auto-handler for horizontally conveying a carrier on which ICs are mounted of auto-handlers which automatically supply ICs, upon completion of assembly thereof, to a test system and automatically classify and accommodate the ICs based on the result of a test. A conventional carrier positional displacement detection in the horizontal conveyance type auto-handler will be described next.  
           [0005]    [0005]FIG. 3 is a view showing a conventional carrier positional displacement detecting mechanism provided with IC sockets, carriers, contact pushers, and the like. FIG. 4 is a sectional view taken along guide pins in FIG. 3. As shown in FIGS. 3 and 4, a plurality of IC sockets  3  are provided on a test board  2 , while guide pins  3 a are provided upright on each IC socket. Guide pins  1  are provided upright on the test board  2 .  
           [0006]    A carrier  4  is conveyed horizontally by a conveyance mechanism, not shown, in the direction of an arrow A in FIG. 3 while a plurality of carrier dowels  5  for holding individual ICs  7  are provided on the carrier  4 . The carrier  4  conveyed onto the test board  2  is lowered toward the test board  2  by an elevating mechanism, not shown, in the direction of the arrow B in FIG. 4.  
           [0007]    When the carrier  4  is lowered, guide pins  1  on the test board  2  are inserted into and engaged in holes  4 a defined in the carrier  4 . As a result, the entire carrier  4  is positioned relative to the test board  2 . Thereafter, guide pins  3   a  on the IC sockets  3  are inserted into and engaged in carrier dowel guide holes  5   a  defined in each carrier dowel  5  corresponding to each IC socket  3 , so that individual ICs  7  are positioned relative to the IC sockets  3 .  
           [0008]    After positioning of each IC  7  relative to each IC socket  3 , the contact pusher  6  is lowered from the above of the carrier  4  so that the ICs  7  on the carrier  4  are forced to contact the IC sockets  3  by the contact pusher  6 , thereby testing the ICs  7 .  
           [0009]    However, according to the conventional carrier positional displacement detecting mechanism having the construction set forth above, if the carrier  4  conveyed onto the test board  2  is lowered while it is not located at a normal position owing to a faulty operation of the conveyance mechanism or setting error by an operator, there occurs a problem that the guide pins  1  on the test board  2  are not inserted or engaged into the guide holes  4   a,  and further the contact pusher  6  is lowered, so that the carrier  4  is sandwiched between the contact pusher  6  and the guide pins  1 .  
           [0010]    To solve the foregoing inconvenience, for example, it is conceived such a construction the position of the carrier  4  is detected by a sensor which is installed previously, then the carrier  4  is lowered toward the test board  2 . However, this construction has a drawback that it takes time for detecting the position of the carrier  4  by the sensor, causing a problem that index time is prolonged.  
         SUMMARY OF THE INVENTION  
         [0011]    In view of the foregoing circumstances, the foregoing problem of the positional displacement of a carrier is solved by detecting a positional displacement of the carrier when the carrier is positioned relative to a test board, and it is an object of the invention to provide and advantageous carrier positional displacement detecting mechanism without taking time for detecting the position.  
           [0012]    A first aspect of the invention resides in a carrier positional displacement detecting mechanism provided in an auto-handler comprising, as shown in FIG. 1, a carrier ( 4 ) for mounting an IC thereon, and a measuring part ( 2 ) for measuring the IC mounted on the carrier ( 4 ), said carrier ( 4 ) having a positioning hole ( 4   a ), and a measuring part ( 2 ) having a projection ( 11 ) wherein the projection ( 11 ) is inserted into the positioning hole ( 4   a ) so as to position the carrier ( 4 ) relative to the measuring part ( 2 ), and wherein the carrier positional displacement detecting mechanism comprises positional displacement time contact means ( 8 ) projected from and disposed on each tip end of the projection ( 11 ) and capable of passing through the positioning hole ( 4   a ) only when the projection ( 11 ) and the positioning hole ( 4   a ) correspond to each other, and contact detection means ( 9 ) for detecting the contact between the positional displacement time contact means ( 8 ) and the carrier ( 4 ) and outputting a carrier positional displacement signal.  
           [0013]    The carrier positional displacement detecting mechanism according to the second aspect of the invention is characterized in that the positional displacement time contact means ( 8 ) in the first aspect of the invention is a shaft projected from and biased by the projection ( 11 ) and the contact detection means ( 9 ) is in the first aspect of the invention is a sensor for detecting a rear end ( 8   b ) of the shaft ( 8 ).  
           [0014]    The carrier positional displacement detecting mechanism according to the third aspect of the invention is characterized in that the positioning operation of the carrier ( 4 ) is stopped when the contact detection means ( 9 ) detects the carrier positional displacement signal.  
           [0015]    The reference numerals set forth here are provided for comparing with the attached drawings, but they do not constituents of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 is view showing a state where the position of a carrier in a carrier positional displacement detecting mechanism according to a preferred embodiment of the invention is displaced.  
         [0017]    [0017]FIG. 2 is view showing a state where the position of a carrier is in a carrier positional displacement detecting mechanism according to a preferred embodiment of the invention is in a normal position.  
         [0018]    [0018]FIG. 3 is a view showing a conventional carrier positional displacement detecting mechanism provided with IC sockets, carriers, contact pushers, and the like.  
         [0019]    [0019]FIG. 4 is a sectional view taken along guide pins in FIG. 3.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]    [0020]FIG. 1 is view showing a state where the position of a carrier in a carrier positional displacement detecting mechanism according to a preferred embodiment of the invention is displaced, wherein FIG. 1(A) shows a state before the carrier is lowered, and FIG. 1(B) shows a state after the carrier is lowered. FIG. 2 is view showing a state where the position of a carrier is in a carrier positional displacement detecting mechanism according to a preferred embodiment of the invention is in a normal position, wherein FIG. 2(A) shows a state before the carrier is lowered, and FIG. 2(B) shows a state after the carrier is lowered.  
         [0021]    Basic constituents such as a test board, carriers, contact pushers, and the like are substantially the same as those set forth in the prior art of the invention (see FIGS. 3 and 4), and the improvement of the invention resides in the constituent of guide pins provided on the test board and the neighborhood thereof. Accordingly, the constituents of the test board and carriers, and the like as described in the prior art are depicted by the same reference numerals and the explanation thereof is omitted.  
         [0022]    A guide pin  11  (positioning projection) is provided on a carrier  4  instead of the guide pin  1  as explained in the prior art with reference to FIGS. 1 and 2, and it is inserted into a guide hole  4   a  of the carrier  4  for positioning the carrier  4 . A through hole  1   a  is formed on the center of the guide pin  11 , and a shaft  8  or contact means at positional displacement time (hereinafter referred to as positional displacement time contact means) is inserted into the through hole  11   a  to be freely movable up and down.  
         [0023]    A compression coil spring  10  (hereinafter simply referred to as a spring  10 ) is provided inside the through hole  11   a  for protruding and biasing the shaft  8  upward. The tip end  8   a  of the shaft  8  protrudes more than that of the guide pin  11 , and the rear end  8   b  of the shaft  8  protrudes downward (lower side of the test board  2 ) more than the lower end of the guide pin  11 . An optical sensor  9  (contact detection means) is provided at the position where the rear end  8   b  of the shaft  8  is forced to enter and extract from the through hole  11   a  when the shaft  8  is moved up and down. The carrier positional displacement detecting mechanism is structured by the constituents set forth above. The contact detection means may be replaced by a contact-type or non-contact type contact detection means.  
         [0024]    In a normal operation, as shown in FIG. 2(A), the carrier  4 , on which a non -measured IC  7  (not shown) is mounted, is conveyed onto the test board  2  (measuring part). Since the carrier  4  is correctly positioned on the test board  2  in the case as illustrated in FIG. 2(A), when the carrier  4  is lowered toward the test board  2 , the guide pin  11  is inserted and engaged in the positioning hole  4   a  of the carrier  4  so that the carrier  4  is properly positioned onto the test board  2  as shown in FIG. 2(B).  
         [0025]    As shown in FIGS.  2 (A) and  2 (B), the tip end  8   a  of the shaft  8  does not contact the carrier  4  and the like, the shaft  8  does not move up and down, and hence the rear end  8   b  of the shaft  8  does not intercept the optical sensor  9 . That is, in this case, the positional displacement of the carrier  4  is not detected, and hence the lowering operation and the like of the carrier  4  are not interrupted.  
         [0026]    Then, although the carrier  4  is lowered even if the position of the conveyed carrier  4  is displaced from the test board  2  as shown in FIG. 1(A), the guide pin  11  provided on the test board  2  is neither inserted and nor engaged in the positioning hole  4   a  of the carrier  4 , and hence the tip end  8   a  of the shaft  8  is brought into contact with the portion other than the positioning hole  4   a  of the  4  as shown in FIG. 1(B). As a result, the shaft  8  is moved downward while resisting the spring  10 , so that the rear end  8   b  of the shaft  8  intercepts the optical sensor  9 .  
         [0027]    When the optical sensor  9  is intercepted, it outputs a carrier positional displacement detection signal. A controller of an autohandler, not shown, interrupts the lowering of the carrier  4  based on the carrier positional displacement detection signal. As a result, the inconvenience that the carrier  4  is sandwiched between the contact pressure and the guide pin is solved. Thereafter, the carrier  4  is once raised up to the conveyance position and adjusted in position, then it is lowered again, and the positioning operation of the carrier  4  is resumed again.  
         [0028]    As mentioned in detail above, since the invention adopts the carrier positional displacement detecting mechanism, even if the position of the carrier  4  is not detected in advance before the carrier  4  is lowered, the optical sensor  9  outputs the detection signal only in the case where the position of the carrier  4  is displaced when the carrier  4  is actually lowered, so that the lowering of the carrier  4  is interrupted. That is, additional time for detecting position of the carrier  4  is not required, and hence an index time is not prolonged, which is very convenient.  
         [0029]    According to the invention, only in the case where the position of the carrier  4  is displaced when the carrier  4  is actually lowered, the positional displacement time contact means contacts the carrier  4 , and the contact detection means outputs the positional displacement detection signal. In such a manner, the positional displacement of the carrier  4  is detected. When the positional displacement of the carrier  4  is detected, it is possible to take measures for interrupting the lowering of the carrier  4 , so that the deformation or breakage of the carrier  4  can be prevented in advance. Further, additional time for detecting position of the carrier  4  is not required, and hence the operation time is not extended, which is very convenient.  
         [0030]    Further, according to the invention, it is possible to structure the carrier positional displacement detecting mechanism with a simple construction comprising the shaft and the sensor for detecting the rear end of the shaft.