Variable-pitch pick and place device

Abstract

Improved variable-pitch pick and place devices may include one or more improvements such as a mechanical linkage such as pantograph linkage, the linkage itself linked to a plurality of device-gripping mechanisms arranged in a row so as to keep uniform, though variable, spacing between the device-gripping mechanisms, with the number of such mechanisms being increased relative to the number of parts in the linkage for reduced tolerance stack-up and improved positioning accuracy. The horizontal position of the linkage may be fixed at a position not at an end thereof, and desirably within the middle third or at the middle thereof. The linkage may be controlled at three points. These point may include a vertically flexible but horizontally fixed link to a supporting structure at the middle of the pantograph, a link at one end of the pantograph to one side of an endless loop of timing belt, and a link at the other end of the pantograph to the other side of the endless loop of timing belt. The links to the timing belt at the ends of the pantograph may be made via two end-most device-gripping mechanisms. The position of the timing belt may be controlled by a servomotor with a position encoder, the servomotor controlled by a controller such as a computer. The device-gripping mechanisms may include a vacuum tip grounded and supplied with vacuum by an electrically-conductive vacuum tube.

I claim:  
     
         1 . A method for moving electronic devices from a first location to a second location using a plurality of electronic-device grippers which are spaced apart from each other along a row, the method comprising: 
 picking up electronic devices with the electronic-device grippers at the first location and with the electronic-device grippers at a first pitch or spacing;    selecting a desired pitch or spacing for the electronic-device grippers; and    electronically controlling the adjustment of the pitch between the electronic-device grippers from the first pitch to the desired pitch.    
     
     
         2 . The method of  claim 1  further comprising moving the electronic-device grippers, and thereby the electronic devices carried by the electronic-device grippers, from the first location to the second location, and releasing the electronic devices from the electronic-device grippers at the second location.  
     
     
         3 . The method of  claim 1  further comprising picking up respective electronic devices with the electronic-device grippers from a first holder at the first location, adjusting the pitch between the electronic-device grippers to the desired pitch, and placing the electronic devices in a second holder at the second location.  
     
     
         4 . A method for moving electronic devices from a first location to a second location with a plurality of electronic-device grippers arranged in a row and spaced apart from each other along the row, the method comprising: 
 picking up respective electronic devices with the electronic-device grippers at the first location and with the electronic-device grippers at a first pitch or spacing;    selecting a value corresponding to a desired pitch or spacing for the electronic-device grippers from a look up table; and    adjusting the pitch between the electronic-device grippers to a desired pitch based upon the value obtained from the look up table.    
     
     
         5 . A method for moving electronic devices, comprising: 
 providing a plurality of electronic-device grippers arranged in a row and a frame supporting said plurality of electronic-device grippers for movement along the row;    picking up respective electronic devices with said plurality of electronic-device grippers; and    adjusting the spacing between adjacent electronic-device grippers to adjust the spacing between adjacent electronic devices while maintaining the center of the row of electronic-device grippers at a fixed position relative to the frame and maintaining equal spacing between adjacent electronic-device grippers.    
     
     
         6 . The method of  claim 5  wherein the act of picking up respective electronic devices with said plurality of electronic-device grippers comprises moving at least selected electronic-device gripper downwardly to a down position for picking up a respective electronic device, detecting whether all of the selected electronic-device grippers are in the down position, and activating each of the selected electronic-device gripper to grip a respective electronic device while in the down position.  
     
     
         7 . The method of  claim 6  comprising optically detecting whether all of the selected electronic-device grippers are in the down position.  
     
     
         8 . The method of  claim 6  wherein all of the electronic-device grippers are moved together to the down position.  
     
     
         9 . A method for moving electronic devices with a plurality of gripper mechanisms, the method comprising: 
 moving at least one of the gripper mechanisms downward toward a down position for gripping a respective electronic device;    detecting whether the at least one of the gripper mechanisms is in the down position;    activating the at least one gripper mechanism to grip a respective electronic device;    moving the at least one gripper mechanism upward toward an up position; and    adjusting the spacing between gripper mechanisms.    
     
     
         10 . The method of  claim 9  further comprising optically detecting whether all of the gripper mechanisms are in the down position.  
     
     
         11 . The method of  claim 9  further comprising detecting whether all of the gripper mechanisms are in the up position prior to adjusting the spacing between the gripper mechanisms.  
     
     
         12 . The method of  claim 9  comprising the act of electronically controlling the adjusting of the spacing.  
     
     
         13 . The method of  claim 12  further comprising detecting whether all of the gripper mechanisms are in the up position prior to adjusting the spacing between the gripper mechanisms.  
     
     
         14 . A method for moving electronic devices comprising: 
 providing a plurality of gripper mechanisms arranged in a row and carried by a pantograph linkage for movement along the row;    picking up the electronic devices with a respective gripper mechanism; and    applying a moving force to the pantograph linkage adjacent to one end of the row in a first direction and applying a moving force to the pantograph linkage mechanism adjacent to the other end of the row in a second direction opposite the first direction for varying the length of the pantograph linkage and thereby changing the spacing between the gripper mechanisms along the row.    
     
     
         15 . The method of  claim 14  wherein the moving force is applied in the first direction to the outermost gripper mechanism at the one end of the row to thereby apply the force in the first direction to the pantograph linkage through such gripper mechanism and wherein the moving force is applied in the second direction to the outermost gripper mechanism at the other end of the row to thereby apply the force in the second direction to the pantograph linkage through such gripper mechanism.  
     
     
         16 . The method of  claim 15  further comprising rotating a tensile-force transmitting member coupled to each of the outermost gripping mechanisms to apply the moving force in the first and second directions to the outermost gripper mechanisms to vary the length of the pantograph linkage.  
     
     
         17 . A method for varying the spacing between electronic devices carried by a plurality of gripper mechanisms arranged in a row, the method comprising: 
 applying a vacuum to the gripper mechanisms to cause the gripper mechanisms to carry respective electronic devices;    electronically controlling the adjustment of the spacing between gripper mechanisms, to vary the spacing between the electronic devices carried by the gripper mechanisms from a first spacing to a second spacing.    
     
     
         18 . The method of  claim 17  further comprising moving the gripper mechanisms, and thereby the electronic devices carried by the gripper mechanisms, from a first location to a second location, and releasing the vacuum on the gripper mechanisms to place the electronic devices at the second location.  
     
     
         19 . The method of  claim 17  wherein the gripper mechanisms are supported on a pantograph linkage and the method further comprises the act of maintaining a first location of the pantograph linkage at a fixed position when the spacing between gripper mechanisms is adjusted to the second spacing.  
     
     
         20 . The method of  claim 19  wherein the first location is in the middle third of the row.  
     
     
         21 . The method of  claim 20  wherein the first location is at the center of the row.  
     
     
         22 . The method of  claim 17  wherein the gripper mechanisms are supported on a pantograph linkage and a tensile-force member is coupled to the outermost gripper mechanism at each end of the row, and the act of electronically adjusting the pitch between gripper mechanisms comprises electronically controlling the movement of the tensile-force member from a first position to a second position to cause a change in the length of the pantograph linkage and a corresponding change in spacing between the gripper mechanisms to the desired spacing.  
     
     
         23 . A method of supporting electronic-device grippers so as to be of variable pitch or spacing, the method comprising: 
 supporting a plurality of electronic-device grippers on a pantograph having first and second ends at spaced apart locations;    extending the pantograph in a first direction to increase the pitch between the electronic-device grippers and retracting the pantograph in a second direction opposite of the first direction to decrease the pitch between the electronic-device grippers; and    restricting a first location of the pantograph from movement in the first and second directions, the first location being intermediate the first and second ends of the pantograph.    
     
     
         24 . The method according to  claim 23  wherein the first location is within the middle third of the pantograph.  
     
     
         25 . The method according to  claim 24  wherein the first location is at the center of the pantograph.  
     
     
         26 . The method according to  claim 23  wherein the act of supporting comprises supporting a plurality of electronic-device grippers on a vertically oriented pantograph.  
     
     
         27 . The method according to  claim 23  comprising the act of applying a force to respective second and third locations of the pantograph to extend and retract the pantograph, the second and third locations being on opposite sides of the first location from one another and adjacent to the respective first and second ends of the pantograph.  
     
     
         28 . A method of extending and retracting a pantograph supporting a plurality of electronic-device grippers to vary the pitch or spacing between the electronic-device grippers, the method comprising: 
 coupling a tensile force transmitting member to the pantograph at first and second spaced apart locations;    driving the tensile force transmitting member in a first direction to extend the pantograph and increase the spacing between the electronic-device grippers;    driving the tensile force transmitting member in a second direction opposite to the first direction to retract the pantograph and decrease the spacing between the electronic-device grippers; and    electronically and selectively controlling the driving of the tensile force transmitting member.    
     
     
         29 . The method according to  claim 28  comprising the act of electronically controlling a drive motor to control the driving of the tensile force transmitting member.  
     
     
         30 . The method according to  claim 28  comprising the act of electronically controlling the driving of the tensile force transmitting member in response to values from a lookup table.  
     
     
         31 . The method according to  claim 28  wherein the act of driving a tensile force transmitting member comprises driving a timing belt.