Scribing head, and scribing apparatus and scribing method using the scribing head

Abstract

A scribing head 1 of this invention raises and lowers a scribing cutter by rotation of a servomotor 3. As a scribe pressure, a rotational torque of the servomotor 3 is transmitted to the scribing cutter. To form a scribe line across another scribe line which is formed earlier, the scribe pressure is raised temporarily when the scribing head passes the scribe line which is formed earlier. The rotational torque of the servomotor 3 is controlled at any of preset limits while the position of a cutter 6 of the scribing head shifts on the brittle substrate. The servomotor 3 is driven under position-control mode.

1. A scribing head equipped with a scribing cutter for forming a scribe line on a brittle substrate, the scribing cutter being positioned by a servomotor which is driven under position-control mode so as to raise and lower the scribing cutter, wherein
 when the scribing cutter deviates from a position set by the servomotor, the driving torque is limited while it acts to reposition the scribing cutter to the position set by the servomotor, and a driving torque is transmitted to the scribing cutter as a scribe pressure.  
 
     
     
       2. A scribing head according to  claim 1 , wherein transfer movement of the servomotor is converted to vertical movement through a gear, and  the driving torque is applied as a scribe pressure. 
     
     
       3. A scribing head according to  claim 1 , wherein a scribe line is formed across another scribe line which is formed earlier, with the scribe pressure being raised temporarily when the scribing head passes the scribe line which is formed earlier. 
     
     
       4. A scribing head according to  claim 1 , wherein the driving torque of the servomotor is controlled at any of present limits while the position of the cutter of the scribing head shifts on the brittle substrate. 
     
     
       5. A scribing head according to  claim 1 , wherein the servomotor sets the position of the scribing head so as to locate below a top surface of the brittle substrate, and substantially at the same time as the start of a scribing action, the thus set position is lowered further to a predetermined position. 
     
     
       6. A scribing head according to  claim 1 , comprising:
 a scribing head body which runs on a brittle substrate;  
 a tip holder mounted on the scribing head body via a support shaft which extends parallel to a surface of the brittle substrate, the tip holder being freely swingable around the axis of the support shaft; and  
 a cutter wheel tip attached to the tip holder via a rotation shaft which extends parallel to the surface of the brittle substrate, the cutter wheel lip being freely rotatable around the axis of the rotation shaft.  
 
     
     
       7. A scribing head according to  claim 6 , wherein the tip holder is mounted via a turning shaft which extends orthogonally to the surface of the brittle substrate, the tip holder being freely swingable around the axis of the turning shaft. 
     
     
       8. A scribing head according to  claim 7 , wherein the rotation shaft is offset from the axis of the turning shaft toward the support shaft. 
     
     
       9. A scribing head according to  claim 6 , wherein the axis of the support shaft locates on or above a vector line of a reaction force which derives from the brittle substrate and which is exerted on the cutter wheel tip during the scribing action. 
     
     
       10. A scribing apparatus for scribing a brittle substrate by moving a scribing head which is equipped with a scribing cutter for forming a scribe line on the brittle substrate,
 wherein the scribing apparatus is equipped with a scribing head according to any one of  claims 1  to  4 ,  5 ,  6  or  9 .  
 
     
     
       11. A method for scribing a brittle substrate, using a scribing head which comprises: a scribing head body according to any one of  claims 1  to  4 ,  5  or  6  to  9 , which runs on the brittle substrate; a tip holder mounted on the scribing head body via a support shaft which extends parallel to a surface of the brittle substrate, the tip holder being freely swingable around the axis of the support shaft; and a cutter wheel lip attached to the tip holder via a rotation shaft which extends parallel to the surface of the brittle substrate, the cutter wheel tip being freely rotatable around the axis of the rotation shaft,
 wherein the scribing head forms a scribe line on the surface of the brittle substrate by running on the brittle substrate, with the support shaft locating behind the cutter wheel tip.  
 
     
     
       12. A method for scribing a brittle substrate according to  claim 11 , wherein the tip holder is mounted via a turning shaft which extends orthogonally to the surface of the brittle substrate, the tip holder being freely swingable around the axis of the turning shaft. 
     
     
       13. A method for scribing a brittle substrate according to  claim 12 , wherein the rotation shaft is offset from the axis of the rotation shaft toward the support shaft. 
     
     
       14. A method for scribing a brittle substrate according to  claim 11 , wherein a reaction force which derives from the brittle substrate and which is exerted on the cutter wheel tip during the scribing action, is oriented along a line which connects the origin of the reaction force and the axis of the support shaft, or oriented nearer to the brittle substrate relative to the line. 
     
     
       15. A scribing head according to any one of  claims 1  to  4 ,  5 , or  6  to  9  wherein the scribing head raised and lowers in a direction perpendicular to a major surface of the brittle substrate. 
     
     
       16. A method for scribing a brittle substrate, equipped with a scribing cutter for forming a scribe line on the brittle substrate, the scribing cutter being positioned by a servomotor which is driven under position-control mode so as to raise and lower the scribing cutter, the brittle substrate being scribed with a driving torque of the servomotor which is transmitted to the scribing cutter as a scribe pressure, wherein when the scribing cutter deviates from a position set by the servomotor, the driving torque is limited while it acts to reposition the scribing cutter to the position set by the servomotor. 
     
     
       17. A method for scribing a brittle substrate according to  claim 16 , wherein transfer movement of the servomotor is converted to vertical movement through a gear, and the driving torque is applied as a scribe pressure. 
     
     
       18. A method for scribing a brittle substrate according to  claim 16 , wherein a scribe line is formed across another scribe line which is formed earlier, with the scribe pressure being raised temporarily when the scribing head passes the scribe line which is formed earlier. 
     
     
       19. A method for scribing a brittle substrate according to  claim 16 , wherein the driving torque of the servomotor is controlled at any of preset limits while the position of the scribing cutter of the scribing head shifts on the brittle substrate. 
     
     
       20. A method for scribing a brittle substrate according to  claim 16 , wherein the servomotor sets the position of the scribing head so as to locate below a top surface of the brittle substrate, and substantially at the same time as the start of a scribing action, the thus set position is lowered further to a predetermined position. 
     
     
       21. A method for scribing brittle substrate according to any one of  claims 16  to  20 , wherein transfer movement of the servomotor is converted to vertical movement through a gear, and the driving torque is applied as a scribe pressure. 
     
     
       22. A scribing head equipped with a scribing cutter, the scribing cutter being movable toward and away from a surface of a brittle substrate and forming a scribe line on the brittle substrate by applying a pressure on the surface of the brittle substrate,
   the scribing head comprising:        a servomotor for moving the scribing cutter toward and away from the surface of the brittle substrate and biasing the scribing cutter onto the surface of the brittle substrate.      
     
     
       23. A scribing head according to  claim 22 , further comprising:
   a controller which outputs a position command signal for moving the scribing cutter to a predetermined position, and a torque command signal for determining a torque limit of a rotational torque generated by the servomotor; and        a servo amplifier which outputs a drive signal to the servomotor, the drive signal being such that the servomotor is driven in a rotation direction of a rotation shaft of the servomotor by a rotational torque not higher than the torque limit, wherein the rotation direction of the rotation shaft corresponds to a direction of moving the scribing cutter to the predetermined position indicated by the position command signal.      
     
     
       24. A scribing apparatus comprising:
   a scribing head according to    claim 22   ,        means for holding the brittle substrate; and        means for moving the scribing cutter relative to the brittle substrate in a direction along the surface of the brittle substrate.      
     
     
       25. A scribing apparatus comprising:
   a scribing head according to    claim 23   ,        means for holding the brittle substrate; and        means for moving the scribing cutter relative to the brittle substrate in a direction along the surface of the brittle substrate.      
     
     
       26. A scribing apparatus according to  claim 25 , wherein
   the predetermined position of the scribing cutter indicated by the position command signal is a position closer to a second surface of the brittle substrate rather than a position where the scribing cutter contacts a first surface of the brittle substrate,        the torque limit includes a first torque limit, a second torque limit and a third torque limit, the first torque limit and the third torque limit being smaller than the second torque limit, and        as the torque command signal the controller outputs the first torque limit when the scribing cutter rides on the brittle substrate, outputs the second torque limit when the scribing cutter moves on the surface of the brittle substrate, and outputs the third torque limit when the scribing cutter comes out of the surface of the brittle substrate, based on a position and a movement direction of the scribing cutter relative to the brittle substrate.      
     
     
       27. A scribing apparatus according to  claim 25 , wherein
   the torque limit includes a second torque limit and a fourth torque limit that is greater than the second torque limit, and        the controller outputs the second torque limit when the scribing cutter moves on a part of the surface of the brittle substrate which does not contain another scribe line, and outputs the fourth torque limit when the scribing cutter moves across another scribe line.      
     
     
       28. A method for scribing a brittle substrate, wherein a scribe line is formed on a brittle substrate with use of a scribing cutter which is movable toward and away from a surface of the brittle substrate and which forms the scribe line on the brittle substrate by applying a pressure on the surface of the brittle substrate,
   the method comprising the steps of:        moving, by controlling a servomotor, the scribing cutter toward and away from the surface of the brittle substrate so as to bring the scribing cutter to a predetermined position, and        applying a pressure to the brittle substrate via the scribing cutter by setting a rotational torque of the servomotor at a predetermined torque limit.      
     
     
       29. A method for scribing a brittle substrate according to  claim 28 , wherein the predetermined position of the scribing cutter is a position closer to a second surface of the brittle substrate rather than a position where the scribing cutter contacts a first surface of the brittle substrate, and the torque limit includes a first torque limit, a second torque limit and a third torque limit, the first torque limit and the third torque limit being smaller than the second torque limit,
   the method comprising the steps of:        setting the torque limit at the first torque limit so as to move the scribing cutter onto the brittle substrate,        setting the torque limit at the second torque limit so as to move the scribing cutter along the surface of the brittle substrate and form a scribe line, and        setting the torque limit at the third torque limit after formation of the scribe line, so as to move the scribing cutter out of the surface of the brittle substrate.      
     
     
       30. A method for scribing a brittle substrate according to  claim 28 , wherein
   the torque limit includes a second torque limit and a fourth torque limit that is greater than the second torque limit, and        the torque limit is set at the second torque limit when a scribe line is formed on a part of the surface of the brittle substrate which does not contain another scribe line, and is set at the fourth torque limit when the scribing cutter moves across another scribe line.