text: the present invention will be now described in detail with reference to the accompanying drawings , in which preferred embodiments of the present invention are shown . fig2 is a perspective view illustrating primary parts of a test handler according to the present invention , and fig3 is a block diagram illustrating primary parts of the test handler according to the present invention . referring to fig2 and fig3 , the test handler according to the present invention includes three transfers 200 ′, 200 ″, and 200 ′″, three horizontal movement units 300 ′, 300 ′″, and 300 ′″, and a controller . the three transfers 200 ′, 200 ″, and 200 ′″ transfer user trays under a transfer standby state to a transfer position , and the three horizontal movement units 300 ′, 300 ″, 300 ′″ independently move the three transfers 200 ′, 200 ″ and 200 ′″ in a horizontal direction . on the other hand , the symbol ‘ t ,’ which is not described in detail , indicates an installation plate on which all of the elements are installed . the following will describe the configuration of the test handler in detail . the three transfers 200 ′, 200 ″, and 200 ′″ will be renamed as follows : reference numeral 200 ′ is 5 referred to as a first transfer suitable for performing a movement operation within a first section a ; reference numeral 200 ″ is referred to as a second transfer suitable for performing a movement operation within a second section b ; and 200 ″ is referred to as a third transfer suitable for performing a movement operation within a third section c . the first to third transfers 200 ′, 200 ″ and 200 ′″ each include a gripper 21 suitable for selectively gripping and un - gripping a user tray , and a vertical movement unit 22 suitable for moving the gripper 21 in a vertical direction . the gripper 21 will not be fully described in this application because the configuration thereof was described in detail in the cited reference . the vertical movement unit 22 includes a vertical guide rail 22 a enabling the gripper 21 to move up and down in a vertical direction therealong , a motor 22 b supplying mechanical power thereto so that the gripper 21 can perform a vertical direction movement . also , in order to transfer the mechanical power of the motor 22 b to the gripper 21 , the vertical movement unit 22 includes a transfer shaft 22 c , a pulley 22 d installed at one end of the transfer shaft 22 c , a motor pulley 22 e installed at the rotation 20 shaft of the motor 22 b , and a belt 22 f connecting the pulley 22 d to the motor pulley 22 e . in addition , the vertical movement unit 22 further includes a holding plate 22 g holding the vertical guide rail 22 a . therefore , the vertical movement unit 22 enables the gripper 21 to move up and down as the mechanical power of the motor 22 b is transferred to the gripper 21 through the motor pulley 22 e , pulley 22 d and transfer shaft 22 c , according to 25 forward and backward rotations of the motor 22 b . although the gripper 21 and the vertical movement unit 22 are installed at each of the first to third transfers 200 ′, 200 ″ and 200 ′″, the other grippers and vertical movement units of the first to third transfers 200 ′, 200 ″ and 200 ′″ are numbered by the same numerals as 21 and 22 in fig2 , for a brief description . on the other hand , the three horizontal movement units 300 ′, 300 ″, and 300 ′″ will be renamed as follows : reference numeral 300 ′ is referred to as a first horizontal movement unit which can move the first transfer 200 ′ in a horizontal direction within the first section a ; reference number 300 ″ is referred to as a second horizontal movement unit which can move the second transfer 200 ″ in a horizontal direction within the second section b , and reference numeral 300 ′″ is referred to as a third horizontal movement unit which can move the third transfer 200 ′″ in a horizontal direction within the third section c . more specifically , the first horizontal movement unit 300 ′ horizontally moves the first transfer 200 ′ within the first section a such that the first transfer 200 ′ can transfer a user tray ( not shown ) under a transfer standby state onto the loading plate . the user tray includes one of a plurality of target devices to be tested ( not shown ), which are stacked on a stacker ( not shown ). the stacker is located under the loading plate . to this end , the first horizontal movement unit 300 ′ includes : horizontal guide rails 31 a and 31 b which guide a holding plate 22 g of the first transfer 200 ′ such that the holding plate 22 g can perform a horizontal movement ; a first motor 32 ′ supplying mechanical power for the horizontal movement of the first transfer 200 ′ thereto ; a first a pulley 33 ′ a installed to the rotation shaft of the first motor 32 ′; a first b pulley 33 ′ b installed to a corresponding place which is apart from the first a pulley 33 ′ a in a horizontal direction ; and a first belt 34 ′ connecting the first a pulley 33 ′ a , the first b pulley 33 ′ b and the holding plate 22 g of the first transfer 200 ′ to each other . here , as shown in fig2 , the first a pulley 33 ′ a is located at one end of the first section a and the first b pulley 33 ′ b is located at the other end . the second horizontal movement unit 300 ″ horizontally moves the second transfer 200 ″ within the second section b in a horizontal direction , such that the second transfer 200 ″ can transfer an empty user tray under a transfer standby state on the loading plate from a gripping position to a transfer position where the empty user tray on an unloading plate is located . here , the second section b is from the gripping position to the transfer position . to this end , the second horizontal movement unit 300 ″ includes : horizontal guide rails 31 a and 31 b which guide a holding plate 22 g of the second transfer 200 ″ such that the holding plate 22 g can perform a horizontal movement ; a second motor 32 ″ supplying mechanical power for the horizontal movement of the second transfer 200 ″ thereto ; a second a pulley 33 ″ a installed to the rotation shaft of the second motor 32 ″; a second b pulley 33 ″ b installed to a corresponding place which is apart from the second a pulley 33 ″ a in the horizontal direction ; and a second belt 34 ″ connecting the second a pulley 33 ″ a , the second b pulley 33 ″ b and the holding plate 22 g of the second transfer 200 ″ to each other . here , as shown in fig2 , the second a pulley 33 ″ a is located at one end of the second section b and the second b pulley 33 ″ b is located at the other end . although the present embodiment is implemented such that first to third horizontal movement units can share the horizontal guide rails 31 a and 31 b , 20 person skilled in the art will easily appreciate that the embodiment can be modified such that each of the horizontal movement units can employ the respective horizontal guide rails . the third horizontal movement unit 300 ′″ horizontally moves the third transfer 200 ′ within the third section c , such that the third transfer 200 ′″ can transfer a user tray ( on which test - finished devices are included ) from a position on an unloading plate to a transfer position , while the tray is under a transfer standby state , such that the test finished devices can be loaded to a stacker installed under the unloading plate . to this end , the third horizontal movement unit 300 ′″ includes : horizontal guide rails 31 a and 31 b which guide a holding plate 22 g of the third transfer 200 ′″ such that the holding plate 22 g can perform a horizontal movement ; a third motor 32 ″ supplying mechanical power for the horizontal movement of the third transfer 200 ′″ thereto ; a third a pulley 33 ′ a installed to the rotation shaft of the third motor 32 ″; a third b pulley 33 ′″ b installed to a corresponding place which is apart from the third a pulley 33 ′″ a in a horizontal direction ; and a third belt 34 ″ connecting the third a pulley 33 ′″ a , the third b pulley 33 ′″ b and the holding plate 22 g of the third transfer 200 ′″ to each other . here , as shown in fig2 , the third a pulley 33 ′″ a is located at one end of the third section c and the third b pulley 33 ′″ b is located at the other end . the first to third horizontal movement units 300 ′, 300 ″ and 300 ′″ are operated such that : when the respective first to third motors 32 ′, 32 ″ and 32 ′″ are operated according to control of the controller 400 , corresponding pulleys ( 33 ′ a , 33 ′ b ; 33 ″ a , 33 ″ b ; 33 ′″ a , 33 ′″ b ) and belts ( 34 ′; 34 ″; 34 ′″) are also operated together , and accordingly the holding plate 22 g of each of the first to third transfers 200 ′, 200 ″ and 200 ′″ is guided by the horizontal guide rails 31 a and 31 b , thereby smoothly moving the first to third transfers 200 ′, 200 ″ and 200 ′″ in a horizontal direction . on the other hand , the controller 400 controls operations of the motor 22 b of the vertical movement unit 22 and the first to third motors 32 ′, 32 ″ and 32 ′″ of the first to third horizontal movement units 300 ′, 300 ″ and 300 ′″ to control operations of the first to third transfers 200 ′, 200 ″ and 200 ′″. the following is a description for the operation of the first to the first transfers 25 200 ′, 200 ″ and 200 ′″ which are controlled by the controller 400 as the test handler starts . for convenient description , each of the first to the first transfers 200 ′, 200 ″ and 200 ′″ will be described , referring to fig4 to fig6 in which only a horizontal movement distance is illustrated . the first transfer 200 ′ grips a user tray 81 that has therein a plurality of target devices to be tested , which is under a transfer standby state , from a stacker 71 located under a loading plate 61 , and then waits near the loading plates 61 , in step s 41 ( a gripper is illustrated as it is located beside the left of the loading plate 61 as shown in fig4 ) while the second transfer 200 ″, whose description will be described in detail later , is gripping an empty user tray from one of the loading plates 61 . afterwards , the first transfer 200 ′ puts the gripped user tray 81 onto the one of the loading plates 61 , in step s 42 , after the second transfer 200 ″ finishes gripping the empty user tray . after that , the first transfer 200 ′ repeats its operation within the first section . the second transfer 200 ″ grips an empty user tray under a transfer standby state from one of the loading plates 61 , where the empty user tray is prepared as the plurality of the target devices to the test tray are transferred to the test tray , and then waits near the unloading plates 62 , in step s 51 ( a gripper 21 is illustrated as it is located beside the left of one of the unloading plates 62 as shown in fig5 ), while the third transfer 200 ′″ ( described in detail later ) is gripping a user tray , having a plurality of tested devices loaded therein , from one of the unloading plates 62 . afterwards , the second transfer 200 ″ puts the gripped empty user tray onto the one of the unloading plates 62 , in step s 52 , after the third transfer 20 ′″ finishes gripping the user tray . after that , the second transfer 200 ″ moves near one of the loading plates 61 , again , and waits for the next operation , in step s 53 ( the gripper 21 is illustrated , in fig5 , as it is located beside the right of one of the loading plates ). then , the second transfer 200 ″ repeats its operations within the second section . on the other hand , wh 5 en an event occurs in a state where all of the devices , which are included in the user tray on the loading plate 61 , are not loaded onto the test tray , the second transfer 200 ″ loads a corresponding user tray onto a stacker numbered by 74 . namely , such an operation is performed to prevent the corresponding user tray moving onto the unloading plate while a device remains on the corresponding user tray on the loading plate 61 . here , the embodiment may be modified such that an additional space can receive the corresponding user tray . also , when an event occurs on one of the unloading plates 62 while any event is not occurring on one of the loading plates 61 , the second transfer 200 ′ grips an empty user tray from a stacker numbered by 73 , in which empty user trays are stacked , and then transfers the empty user tray onto one of the unloading plates 62 in which the event occurred . therefore , the unloading operation is smoothly performed without delay . while the third transfer 200 ′″ waits near one of the unloading plates 62 ( the gripper 21 waits beside the right side of one of the unloading plates 62 in fig6 ), when a user tray is shown , where the user tray is under a transfer standby state as the target devices are unloaded to the test tray , the unloaded user tray is gripped , in step s 62 , and then loaded on a stacker 72 located under one of the unloading plates 62 , in step s 62 . after that , the third transfer 200 ′″ repeats its operation within the third section . as apparent from the above description , the present invention provides a test handler including three transfers each of which has a gripper and a vertical movement unit which moves the gripper in a vertical direction , where the three transfers independently move in a horizontal direction , each transfer has a function such that a previous procedure can be performed before an event occurs , and horizontal movement distance is divided on the basis of 5 functions of the respective transfers such that the respective transfers can move quickly , thereby enhancing the processing speed thereof due to the movement of user trays . although the preferred embodiments of the present invention have been disclosed for illustrative purposes , those skilled in the art will appreciate that various modifications , additions and substitutions are possible , without departing from the scope and spirit of the invention as disclosed in the accompanying claims .