TAPER MACHINE USING INERTIAL CONTROL OF PARTS

Abstract: A method for packaging electronic chips (18) into the compartments of a carrier tape (14) includes feeding a chip into a preselected position with respect to a movable vacuum head (82), taking custody of the chip by way of a vacuum in the vacuum head, moving the vacuum head in a single motion toward the carrier tape without substantially altering the direction of movement of the vacuum head, and interrupting the vacuum in the vacuum head to release the chip into a compartment of the tape. The chips may be fed by gravity feed. The preselected position may be within a slot (58) in a body (50), and the body may be bifurcated to provide access for the vacuum head to the slot. The body may be moved aside after the vacuum head has taken custody of the chip to remove a support surface or floor (56) from under the chip. The chip may then be moved downwardly, either directly or along an arcuate path, in a single motion to position the chip in the tape compartment.

Description: Taper Machine Using Inertial Control of Parts This application claims the benefit of co-pending U.S. Provisional Patent Application No. 60/184,887 filed February 25, 2000. Field of the Invention The invention relates to machines used to load electrical parts or circuit elements, hereinafter referred to generically as chips, into the compartments or pockets of a carrier tape for storage and shipment. Background of the Invention Typically, a manufacturer of chips will create a large number of chips, and the chips will be supported on a temporary carrier medium. The chips are then processed through a quality control machine of one type or another, where the chips are visually inspected for flaws. The chips passing the inspection are then removed from the temporary carrier medium and placed in the compartments or pockets of a carrier tape. The carrier tape is then wound on a reel and stored and eventually shipped to the purchaser of the chips (often a manufacturer of electronic devices such as personal computers). There are several processes and methods known for removing the chips from the temporary carrier medium and placing the chips in the pockets of the carrier tape. Often a pick-and-place device or module is used. In many instances the chips are fed to the pick- and-place device by a gravity feed. The pick-and-place device takes custody of each chip and moves the chip over some distance to the pocket of the carrier tape. To date pick-and-place assemblies have been constructed to move chips to the tape compartment through a series of distinct movements. More specifically, the pick-and- place head is moved to engage an exposed surface of a chip and the head is attached to the chip by means of a vacuum. The pick-and-place head is then moved upwardly and is displaced to one side or the other with the chip attached to the head. Once the chip is positioned over the tape compartment, the head is brought to a stop. Then the pick-and- place head is moved downwardly toward the tape compartment, and the vacuum is released to deposit the chip in the tape compartment. The movement of the pick-and-place head is then retraced to return the head to the start position and repeat the steps just described for the next chip in line. The movement of the head is as rapid as possible to maintain a speedy loading operation, and the chip is therefore subjected to abrupt starts, stops, and changes in direction of movement. As a result, it is not uncommon for chips to dislodge or displace on the head. If the chip is forced off of the head, the chip may in some cases be damaged. If the chip is not separated, but just displaced, the chip may be positioned in the tape compartment in an improper or skewed position, which again can result in damage to the chip and/or disrupt the loading process. Most gravity feed apparatus are angled with respect to horizontal, which requires the pick-and-place head to mirror the angle to facilitate the loading process. Such angular disposition of the head can exaggerate the above-mentioned problems. Summary of the Invention The invention provides a method for packaging electronic chips into the compartments of a carrier tape includes feeding a chip into a preselected position with respect to a movable vacuum head, taking custody of the chip by way of a vacuum in the vacuum head, moving the vacuum head in a single motion toward the carrier tape without substantially altering the direction of movement of the vacuum head, and interrupting the vacuum in the vacuum head to release the chip into a compartment of the tape. The chips may be feed by gravity feed. The preselected position may be within a slot in a body, and the body may be bifurcated to provide access for the vacuum head to the slot. The body may be moved aside after the vacuum head has taken custody of the chip to remove a support surface or floor from under the chip. The chip may then be moved downwardly, either directly on along an arcuate path, in a single motion to position the chip in the tape compartment. Brief Description of the Drawings Figs. 1-5 are schematic representations of the movement of a prior art pick-and- place head as viewed from the side. Fig. 6 is a perspective view of a taper machine embodying the present invention. Figs. 7-9 are side schematic representations of an apparatus embodying the present invention and executing the steps of moving a chip from a feeder to a carrier tape. Figs. 10 and 11 are side schematic representations of an alternative embodiment of the invention. Figs. 12 and 13 are side schematic representations of another alternative embodiment of the invention. Fig. 14 is a view taken from the vantage of line 14-14 in Fig. 13. Detailed Description Figs 1-5 illustrate the operation of a pick-and-place elevator or head 10 executing a prior art method for loading a carrier tape 14. A chip 18 is delivered to a pick-and-place station on an inclined surface 22 of a gravity feed arrangement. The chip 18 engages a stop 26, and is thereby positioned in the pick-and-place station for engagement by the head 10. In Fig. 1, the head 10 is moved toward the chip 18, a vacuum is drawn through the head 10 and the chip 18 is attached to the head 10 by reason of the vacuum. Next, as illustrated in Fig. 2, the head 10 is moved away from the surface 22 to clear the stop 26. At this point it should be noted the chip 18 is being displaced against its own weight and against the inertial forces tending to keep the chip 18 at rest on the surface 22. Of course, the step is preferably conducted as quickly as possible to maximize the efficiency of the tape loading process. The inertial forces that must be overcome are directly related to the speed at which the step is carried out. The vacuum force must therefore be rather strong to insure the head 10 maintains custody of the chip 18 when the step is executed quickly. The strong vacuum creates the possibility of damage to the chip 18 or its exposed leads and/or terminals. Fig. 3 illustrates the next step in the movement of the prior art loading process. In this step, movement of the head 10 away from the surface 22 is stopped, and then the head is pivoted or moved to the left as seen in the drawings to transport the chip 18 to a position over the carrier tape 14. As with the steps described above, this step is preferably carried out very quickly, and thus there are further inertial forces exerted on the chip 18 when movement of the head 10 stops and changes direction quickly. Additionally, at the end of this step, the head 10 is brought to a quick stop over a compartment or pocket in the carrier tape 14, which is yet another change in momentum of the chip 18. In Fig. 4, the chip 18 is quickly lowered by the head 10 to position the chip 18 in the tape compartment. Once the chip 18 is positioned in the tape compartment, the vacuum is momentarily shut off to release the chip 18 into the tape compartment. Fig. 5 illustrates the last step in the prior art loading process. In this step, the head 10 is raised and returned to the position illustrated in Fig. 1. Fig. 6 illustrates a taper machine 30 embodying the present invention and including a tape supply reel 31 and a tape output reel 32. The machine 30 includes an inclined surface or gravity feed apparatus 34 for supporting chips 18 to be packaged in the carrier tape 14. The tape 14 runs from the supply reel 31, through a taper assembly 46, and to the output reel 32. The taper assembly 46 transfers the chips 18 from the inclined surface 34 to the tape 14. A stop 48 is positioned upstream (in the sense of travel along the inclined surface 34) of the taper assembly 46, and provides one chip 18 at a time to the taper assembly 46. Turning to Figs. 7-9, the taper assembly 46 will be discussed in more detail. The taper assembly 46 includes a chip receiving body 50 that has a bifurcated or split nose 54 and a floor 56 that together define a chip receiving slot 58. The nose 54 also includes a cam profile surface 62 extending substantially parallel to the inclined surface 34, and a nose profile surface 66 which is substantially linear and angled down toward the inclined surface 34. Positioned within the slot 58 is a stop 70 that locates the chip 18 within the slot 58. Supported on top of the body 50 is a cam follower 74, which may, for example, be a roller. The cam follower 74 supports a pivot arm 78 which in turn supports a vacuum head 82. The head 82 extends between the two halves of the bifurcated nose 54, and into the slot 58. The pivot arm 78 is fixed for rotation with the cam follower 74 such that the pivot arm 78 and cam follower 74 rotate together. The pivot arm 78 is suitably biased (e.g. by spring or gravity) in the clockwise direction as viewed in Figs. 7-9. The first step of the taping process is illustrated in Fig. 7. A chip 18 slides or is fed down the inclined surface 34 and into the slot 58. The chip 18 is positioned under the head 82 by the stop 70. When the chip 18 is in engagement with the stop 70, a vacuum is drawn in the head 82 so that the head 82 takes custody of the chip 18. The next step is illustrated in Fig. 8, where the body 50 is moved down and to the left as illustrated and substantially parallel to the inclined surface 34. This movement causes the chip 18 to be moved out of the slot 58. As the body 50 is moved, the support floor 56 is moved from underneath the chip 18. The cam follower 74 is held stationary such that the body 50 moves relative to the cam follower 74. Fig. 9 illustrates the next step in the process, in which the chip 18 is deposited into a compartment or pocket of the carrier tape 14. Movement of the cam follower 74 down the nose profile surface 66, causes the cam follower 74 to rotate as illustrated, which in turn causes the pivot arm 78 to pivot and the head 82 to lower. This action moves the chip 18 toward the carrier tape. The vacuum is then interrupted to release the chip 18 from the head 82 and deposit the chip 18 into the tape compartment, and the body 50 is moved to the right as illustrated, causing the pivot arm 78 to raise the head 82 and move the slot 58 into the position shown in Fig. 7. It should be appreciated that the above-described process moves the chip 18 substantially in the direction of the chip's 18 acceleration due to gravity (i.e., in the direction of its weight), and that substantially no inertial forces act on the chip 18 as the chip is moved down into the tape compartment. Any the inertial forces acting on the chip 18 during the downward movement of the head 82 tend to further secure the head's custody of the chip 18. In this manner the chip 18 is transported in single smooth motion step to the tape compartment from the inclined surface 34. Because there are no stops and/or changes in direction between the inclined surface 34 and the tape compartment, and substantially all motion is in the direction of weight of the chip 18, a lower vacuum may be used when compared to prior art arrangements. The taper machine of the present invention therefore minimizes the opportunity for damage to or misalignment of the chip 18. An alternative embodiment is illustrated in Figs. 10 and 11. In this embodiment the chips 18 are transported on a track 86 by a singulator station 90 comprising a suitable belt drive 94 for moving the chips 18 against a stop 98. An air jet 102 moves a selected or singulated chip into a bifurcated body 106 after stop 98 is moved up to release the chip 18. The singulated chip 18 moves against stop 110 and onto support platform or floor 114. When so positioned a vacuum is drawn on vacuum elevator 118 to attach the chip 18 thereto. The body 106 is moved to the right as illustrated by actuator 122 which can be hydraulic or pneumatically operated. As the body 106 is moved, the floor 114 is removed from under the chip 18, and the cam follower 126 attached to the vacuum elevator rides down on the inclined surface 130 lowering the chip 18 toward and into the tape compartment at which time the vacuum is interrupted and the chip 18 is released. The body 106 is then moved to left as illustrated returning the vacuum elevator 118 to the start position to attach to and move a subsequent chip 18 to the tape compartment. Again the chip 18 is moved in a single smooth step and in the direction of the weight of the chip 18 to achieve the advantages mentioned above. Figs. 12 and 13 illustrate another embodiment of the taper assembly 46, in which a singulator stop 134 permits a single chip 18 to slide down the inclined surface 34 into abutment with a stop 138. A vacuum head 142 is pivoted by a drive mechanism 146 to a position above the chip 18. The drive mechanism 146 may include, for example, a motor output shaft or a shaft operatively interconnected with a motor output shaft 147, a pair of sprockets 148, and a flexible force transfer member 149 (e.g., a drive belt or chain). A vacuum is applied through the head 142 to take custody of the chip 18. An actuator 150 is used to pivot or otherwise move a floor member 154 from under the chip 18. Once the floor member 154 is clear of the chip 18, the vacuum head 142 is pivoted down to position the chip 18 in the tape compartment. The vacuum is then interrupted and the vacuum head 142 and floor member 154 are raised to the positions shown in Fig. 12. Fig. 14 illustrates a type of vacuum head 142 that may be employed to assist in keeping custody of the chip 18 during transfer of the chip 18 from the surface 34 to the tape 14. The illustrated head 142 includes a pair of depending members 158 that snugly fit on either side of the chip 18 to further prevent the chip 18 from moving relative to the head 142 during transfer to the tape. It should be noted that the head arrangement illustrated in Fig. 14 may be used with the vacuum heads 82, 118 of Figs. 7-11 as well. It should also be noted that additional depending member 158 may be employed to embrace the chip 18 on three or even four sides to further reduce the likelihood of movement of the chip 18 during transfer.

Claims: CLAIMS 1. A method for packaging electronic chips into the compartments of a carrier tape, the method comprising: feeding a chip into a preselected position with respect to a movable vacuum head; taking custody of the chip by way of a vacuum in the vacuum head; moving the vacuum head in a single motion toward the carrier tape without substantially altering the direction of movement of the vacuum head; and interrupting the vacuum in the vacuum head to release the chip into a compartment of the tape. 2. The method of claim 1 , wherein said act of feeding a chip includes providing a plurality of chips, singulating the chips with a stop to permit a single chip at a time to pass by the stop, and sliding the singulated chip along an inclined surface under the influence of gravity to the preselected position with respect to the vacuum head. 3. The method of claim 1 , further comprising: providing a body defining a slot having a floor surface, wherein said act of feeding includes providing a chip in the slot, and wherein said act of taking custody includes positioning the head adjacent the chip in the slot to expose the chip to the vacuum in the head; and after taking custody of the chip, removing the floor surface from under the chip, wherein said act of moving the vacuum head includes moving the vacuum head substantially downwardly in the direction of the weight of the chip. 4. The method of claim 1 , wherein said feeding a chip step includes supporting the chip under the movable vacuum head with a support surface, the method further comprising removing the support surface from under the chip prior to said act of moving the vacuum head. 5. The method of claim 1 , further comprising providing a body having a nose profile surface, wherein the vacuum head includes a cam follower adapted to follow the nose profile surface in response to movement of the body, and wherein said act of moving the vacuum head includes causing the vacuum head to pivot about the cam follower by moving the body. 6. The method of claim 1 , wherein said act of moving the vacuum head includes pivoting the vacuum head only along a single arcuate path. 7. The method of claim 1, wherein said act of moving the vacuum head includes displacing the head only in a vertical direction. 8. The method of claim 1, wherein said act of moving the vacuum head includes pivoting the vacuum head in response to rotation of an output shaft of a motor. 9. An apparatus for transferring electronic chips from a chip feeding mechanism to a carrier tape having compartments, the apparatus comprising: a vacuum head adapted to take custody of a chip by way of a vacuum applied through the head; and means for moving the vacuum head in a single motion toward the carrier tape without substantially altering the direction of movement of the vacuum head. 10. The apparatus of claim 9, wherein said means for moving includes a body having a nose profile surface, and wherein said vacuum head includes a cam member movable along said nose profile surface in response to movement of said body. 11. In a system for handling electrical circuit units and including a circuit unit loading station, transport means for moving said circuit units to said loading station, and wherein said loading station includes a selectively operable vacuum unit and a circuit unit receiver operatively associated with said vacuum unit, the improvement comprising said vacuum unit supported for movement in a predetermined plane, said circuit unit receiver located in said plane, means for moving said vacuum unit in said plane toward and away from said receiver, means for positioning a circuit unit in said loading station, in said plane, and below said vacuum unit, means for producing a vacuum at said vacuum unit to attach said circuit unit to said vacuum unit for movement therewith, and means for moving said vacuum unit with said circuit unit attached thereto toward said receiver and interrupting said vacuum to release said circuit unit when it is positioned within said receiver. 12. The combination of claim 11 , wherein said receiver is positioned below said transport means. 13. The combination of claim 11 , wherein said vacuum unit moves along an arcuate path in said plane toward and away from said receiver. 14. The combination of claim 11 , wherein said means for moving said vacuum unit includes a cam follower supported for movement in said plane, a circuit unit moving module including a cam surface supported for engagement with and movement relative to said cam follower and a support surface aligned with the path of movement of said circuit units on said transport means to receive and engage a circuit unit and support said engaged circuit unit adjacent said vacuum unit, said cam surface being movable to effect movement of said cam follower in said plane and simultaneously removing said support surface as said circuit unit is attached to said vacuum unit, and wherein said vacuum unit moves in an arcuate path when moving toward and away from said receiver.

Inventors: WEISS MARTIN, WEISS, MARTIN
Applicants: ROBOTIC VISION SYSTEMS, WEISS MARTIN, ROBOTIC VISION SYSTEMS, INC., WEISS, MARTIN
Application year: 2001
Main classification: B65B3
IPC codes: B65B9, B65B35, H05K13