Scribing apparatus

Abstract: A scribing apparatus which forms a scribe line on a work 100 comprises a scribe body 10 having a cutter 13 put on the work 100 and a vibration generation member 14 which vibrates the cutter 13 in a direction perpendicular to the work 100 periodically, a support device having a support body 20 for supporting the scribe body 10 to be movable, and magnetic force applying means 40 for holding the scribe body 10 at a standard height in the direction by using magnetic force. The magnetic force applying means 40 includes a pair of magnets 41a, 41b and a pair of magnets 42a, 42b repulsing each other in a direction parallel to a direction in which the vibration generation member 14 vibrates. And magnetically repelling force applied to the scribe body 10 by said first pair of magnets 41a, 41b and magnetically repelling force applied to the scribe body 10 by said second pair of magnets 42a, 42b oppose to each other.

Description: The present invention relates to a scribing apparatus for forming a scribe line on a surface of a workpiece made of a hard brittle material such as plate glass, ceramics plate, a semicondutor or the like. A scribe apparatus which applies vibrations when forming a scribe line on the surface of a workpiece made of a hard brittle material is conventionally known. This scribing apparatus has a vibration generation member generating a vibration in a scribe body, and the scribing apparatus vibrates the cutter disposed on a lower end of the scribe body. When the cutter stays in contact with the workpiece surface, the scribe body vibrates without changing a position of the cutter. Therefore a pressure applied to the workpiece by the cutter vibrates periodically, and a deep vertical cracks is generated on the workpiece surface in a workpiece thickness direction. In the known scribe apparatus, when the scribe body is vibrated, it is likely that the cutter will be bounced off the workpiece surface and will not stay in contact with the workpiece surface. As a result, damage such as horizontal (lateral) cracks or the like are generated and fine vertical cracks are not formed on the workpiece surface. In order to solve this problem, the Japanese Patent Laid-open Publication No. JP-A-9-278473 discloses an scribing apparatus which applies a static load to the workpiece by using a plate spring or making the weight of the scribe body heavier so as to prevent the cutter from being bounced off the workpiece surface. Also, as shown in Fig. 9, a scribe apparatus that prevent a cutter from being bounced off a workpiece surface by using a weight 1 and spring 2 is proposed (the Japanese Patent Laid-open Publication No. JP-A-11-157860). In this scribe apparatus, the weight 1 is provided above the scribe body 4 through the spring 2, and gravity of the weight 1 applied to the scribe body 4 prevents the cutter 3 from being bounced off the workpiece 5. Total gravity of mass W1 of the weight 1 and mass W2 of the scribe body 2 are given to the workpiece 5 as a static load. However, in a way of applying the static load to the workpiece by making the weight of the scribe body heavier, since the static load applied to the workpiece becomes excessive, horizontal cracks are most likely generated near the scribe line on the surface of the workpiece. Conversely, if the static load is too underestimated, the cutter will be bounced off the workpiece surface, and continuous micro-cracks will not be secured. Also, in a way of applying the static load to the workpiece by using a plate spring, since applying the static load to the workpiece is owing to a spring constant and a natural frequency of the plate spring, resonance will easily occur between the scribe body and the plate spring, so control of the formation of a scribe line is reduced. Further in the scribe method in the Japanese Patent Laid-open Publication No. HEI 11-157860, if a vibration generation member frequency is close to a natural frequency in a system of the spring 2 and the weight 1, the weight 1 will resonate, and an undesirable elastic load will be applied to the scribe body 4 by the spring 2. Also, since the weight 1 is provided, the static load applied to the workpiece 5 from the cutter 3 becomes larger, damage such as horizontal cracks occurs on the surface of the workpiece 5. Further, if the scribe body 4 and the weight 1 are not guided sufficiently, the scribe body 4 will totter, and an appropriate dynamic load will not be applied to the workpiece 5. An object of the present invention is to substantially eliminate defects or drawbacks encountered in the prior art mentioned above and to provide a scribing apparatus for forming deep cracks along a scribe line without occurring the damage on the workpiece surface. It is another object of the present invention to provide a scribe apparatus of that type which applies an appropriate static and dynamic load to the workpiece from the cutter. According to the invention, it is possible to apply an appropriate static load to the workpiece from the cutter. Therefore, scribing apparatus can form deep cracks along a scribe line without occurring a damage on the workpiece surface. According to the present invention there is provided a scribing apparatus for scribing a line on the surface of a workpiece, the apparatus comprising: a scribe body having a cutter and a vibration generation member arranged to periodically vibrate the cutter in use in a direction substantially perpendicular to the surface of the workpiece; a support device having a support body and movable, in use, parallel to the surface of the workpiece; wherein the scribe body is movable, in use, relative to the support body in a direction perpendicular to the surface of the workpiece; characterised by comprising: a magnetic force applying means associated with the support body and the scribe body arranged to apply, in use, a holding magnetic force to the scribe body in a direction perpendicular to the surface of the workpiece to hold, in use, the scribe body in a predetermined position relative to the support body. Embodiments of the present invention will now be described with reference to the accompanying drawings, in which: Fig. 1 is a schematic side view showing an entire structure of a scribing apparatus according to a first embodiment of the present invention; Fig. 2 is a sectional view taken along the line II-II in Fig. 1; Fig. 3 is a schematic side view showing an entire structure of a scribing apparatus according to a second embodiment of the present invention; Fig. 4 is a sectional view taken along the line IV-IV in Fig. 3; Fig. 5 is a perspective view showing a weight; Fig. 6 is a front view showing a lower part of the weight; Fig. 7 is a perspective view showing a rectilinear guide; Fig. 8 is a graph showing a pressure applied to the workpiece by a cutter; Fig. 9 is a schematic side view showing a structure of a scribing apparatus in the prior art; Fig. 1 shows a scribing apparatus according to a first embodiment of the present invention. With reference to Fig. 1, the scribe apparatus comprises a scribe body 10, a support body 20 arranged vertically for supporting the scribe body 10 so that the scribe body movable and having a slide mechanism arranged between the scribe body 10 and the support body 20 which makes the scribe body 10 movable in a vertical direction relative to the support body 20, a magnetic force applying means (a magnetic holding mechanism) 40 for holding the scribe body at a standard height (position) by using vertical magnetic force, a moving mechanism 50 moving the support body 20 in a direction perpendicular to space in Fig. 1, and a table 60 on which a plate-shaped workpiece 100 such as a plate glass or ceramics plate is placed in horizontal plane. A support device described in claim 1 includes said support body 20, said slide mechanism 30, and said magnetic holding mechanism 40. Fig. 2 shows the scribe body 10. The scribe body 10 comprises the body portion 11, a holder 12 supported by the body portion 11 so as to be minutely slidable in the vertical direction, a cutter 13 attached to the lower end of the holder 12 and a vibration generation member 14 having two piezoelectric actuators in series or the like for generating and applying vibrations to the holder 12 in a vertical direction. The body portion 11 has a vertically elongated box-shaped structure, and the holder 12 is accommodated inside the body portion 11. The holder 12 also has a vertically elongated box-shaped structure, and the vibration generation member is accommodated inside the holder 12. The vibration generation member extends vertically, and has a central axis in common with axes of the body portion 11 and the holder 12, the central axis (line) being shown as L in Fig. 2. The vibration is generated along to this axis line L. The vibration generation member 14 has a lower end abutting against a bottom surface of an inner space of the holder 12. The holder 12 also has an upper end supported by a guide member provided at the upper end of the body portion 11 to be minutely slidable in a direction along the central axis L, i.e. vibrating direction. The lower end of the holder 12 is supported by a plate spring 16 laid across the body portion 11 and a spherical ball 30 (as a pre-load applying member) made of an elastic material such as rubber or resin. The ball 30 is disposed between a receiver plate 18 fixed to the body portion 11 and the holder 12. The ball 30 acts to urge the holder 12 upward by its elastic restoring force so as to apply the pre-load (a force in a direction to compress the vibration generation member 14 axially) to the vibration generation member arranged between the body surface of the inner space of the holder 12 and an adjusting screw screwed to the guide member. The holder 12 has a pair of lower forked extensions extending so as to straddle the plate spring 16, and the cutter 13 is mounted to the lower end (front end) of the paired extensions of the holder 12 through attachments 19a, 19b by which a mounting angle of the cutter 13 is adjustable with respect to the holder 12. The cutter 13 is mounted to a position substantially on the central axis line L of the vibration generation member. A lower end portion of the cutter 13 has a conical shape extending downward and is sharp-pointed. The cutter 13 comprises a diamond particle having a substantially quadrangular pyramid shape fixed to the lower end thereof. The apex of the diamond particle points below so as to be put on the surface of the workpiece 100. The slide mechanism 17 (see Fig. 2) comprises a guide 31 fixed to the support body so as to extend vertically and a slider 32 supported by the guide 31 to be slidable in the vertical direction. A hollow 32a extending in the vertical direction is formed on the slider 32. The body portion 11 is put in and fixed to the hollow 32a. The slider 32 composes one part of the scribe body 10. The magnetic holding mechanism 40, which is a distinctive feature in the embodiment of the present invention, has a pair of magnets 41 repelling each other disposed over the slider 32 and a second pair of magnets 42 repelling each other disposed under the slider 32. The first pair of magnets 41 have a permanent magnet 41 a fixed to an upper surface of the slider 32 and a permanent magnet 41b opposing to and vertically alienated from the permanent magnet 41 a, said permanent magnet 41 b being fixed to the support body 20. Said permanent magnet 41 b is provided as follows. Support body 20 has a horizontally extending plate 21 fixed to at the upper end thereof, and a position adjustment mechanism (a magnetic force adjustment) 43 is attached to the horizontally extending plate 21. The structure of the position adjustment mechanism 43 is similar to the structure of a well-known micrometer. The position adjustment mechanism 43 comprises a sleeve 43a fixed to an upper surface of the horizontally extending plate 21, a manually operated case 43b disposed outside a periphery surface of the sleeve 43a, and a spindle 43c of which a projecting amount is adjustable by rotating the manually operated case 43b. The spindle 43a penetrates the horizontally extending plate 21 and extends downward. The permanent magnet 41b is fixed to the lower end of the spindle 43. Therefore, adjusting the projecting amount of the spindle 43a by rotating the manually operated case 43b allow the position (height) of the permanent magnetic 41b to be adjusted. The permanent magnets 41a and 41b are opposing to each other so that identical magnetic polarities (for example N polarities) are put face to face. There is a vertical distance between the permanent magnets 41a and 41b. And repulsive force between permanent magnets 41a and 41b urge the scribe body 10 including the slider 32 downward, that is, toward the workpiece 100. The second pair of magnets 42 have a permanent magnet 42a fixed to a lower surface of the slider 32 and a permanent magnet 42b, fixed to the support body, opposing to and vertically alienated from the permanent magnet 42a. Like the first pair of magnets 41a, 41b, the permanent magnet 42b is provided in the support body through a horizontally extending plate 22 fixed at the lower end thereof and a position adjustment mechanism 45 (a magnetic force adjustment) attached to the horizontally extending plate 22. A sleeve 45a of the position adjustment mechanism 45 is fixed to a lower surface of the horizontally extending plate 22. A spindle 45c projecting upward from the sleeve 45a penetrates the horizontally extending plate 22. The permanent magnet 42b is fixed to the upper end of the spindle 45c. Adjusting the projecting amount of the spindle 45c by rotating the manually operated case 45b allows the position (height) of the permanent magnetic 42b to be adjusted. The permanent magnets 42a and 42b are also opposing to each other so that identical magnetic polarities are put face to face. And repulsive force between permanent magnets 42a and 42b urge the scribe body 10 including the slider 32 upward apart from the workpiece 100, that is, in a direction in which the scribe body 10 is apart from the workpiece 100. From the foregoing description, magnetically repelling force applied to the scribe body 10 by said first paid of magnets 41a, 41b and magnetically repelling force applied to the scribe body 10 by said second pair of magnets 42a, 42b are opposing to each other in a vertical direction parallel to a direction in which the vibration generation member 14 vibrates. And the pair of magnets 41a, 41b and the pair of magnets 42a, 42b are aligned in a axial direction extending vertically. A description of an operation in the scribe apparatus will be given below. As mentioned above, the workpiece 100 is horizontally placed on the table so that the positioning of the workpiece 100 is determined. On the other hand, when the cutter 13 is not put on the workpiece 100, the scribe body 10 is floated by using magnetically repelling force of the pair of magnets 41a, 41b and 42a, 42b in opposite directions and is held at a standard height (position). The magnetic force applied to the scribe body 10 is determined by the height of magnetic 41b and the height of magnetic 42b adjusted by the position adjustment mechanisms 43, 45. When the scribe body 10 is at the standard height, the total of force caused by the own weight of the scribe body 10 and the repulsive force of the-paired magnets 41a, 41b are equal to the repulsive force of paired magnets 42a, 42b. That is, when the scribe body 10 is at the standard height, the repulsive force of the paired magnets 42a, 42b is larger than the repulsive force of the paired magnets 41a, 41b by the weight of the scribe body 10. The standard height of the scribe body 10 is set slightly lower than a height while the scribe body 10 is getting on the workpiece 100 by some amount for example 10 µm. Also, the distance between the paired magnets 41a, 41b and the distance between the paired magnets 42a, 42b, while the scribe body 10 is in the standard height, determine restoring force applied to the scribe body 10 being displaced out of the standard height. At first, the scribe body 10 set in the standard height is horizontally apart from the edge of the workpiece 100. By the moving mechanism which moves the scribe body 10 and the support body 20 to the workpiece 100 horizontally, the cutter 13 gets on the workpiece 100 after hitting the edge of the workpiece 100. A distance between the standard height while the scribe body 10 is not placed on the workpiece 100 and the height while the scribe body 10 is getting on the workpiece 100 is determined by the desirable static load corresponding to the workpiece 100. And since the distance is not set so larger than a necessary distance, the cutter 13 can easily get on the workpiece 100. As the cutter 13 gets on the workpiece 100, the scribe body 10 moves upward out of the standard height. According to this displacement of the scribe body 10, the repulsive force of the paired magnets 41 a, 41 b becomes larger and the repulsive force of the paired magnets 42a, 42b becomes smaller, the scribe body 10 is applied a downward load which restores the scribe body 10 to the standard height. This load as a static load pushes the cutter 13 on the workpiece 100. The static load is based not only on the weight of the scribe body 10 but also on the repulsive force of paired magnets 41a, 41b, 42a, 42b according to the displacement of the scribe body 10 out of the standard height. Therefore, adjusting the displacement of the scribe body 10 by the position adjustment mechanisms 43, 45 can appropriately adjust the static load according to thickness or material of the workpiece 100. As mentioned above, after the cutter 13 is put on the workpiece 100, the cutter 13 is moved by the moving mechanism so as to draw a locus along the surface of the workpiece 100. When the scribe body 10 gets on the workpiece 100 or before the scribe body 10 gets on the workpiece 100, the two vibration generation have been applied an in-phase high frequency voltage and are periodically expanded or contracted in the axial direction. A vibration of the holder 12 caused by the periodic expansion and contraction of the vibration generation members 14, 14 is transmitted to the workpiece 100 through the cutter 13. As a result the cutter 13 forms a scribe line consisting of continuous vertical micro-cracks on the surface of the workpiece 100 along the locus thereof. From the foregoing description, since the static load is changed and made smaller, it is possible to prevent a horizontal cracks from occurring near the scribe line and to form a fine scribe line. By the way, mass which contributes to a vibration energy transmitted from the vibration generating members to the workpiece 100 is determined by the mass of the holder 12, the attachment 19a, 19b and the cutter 13. Also, mass which contributes for receiving a reaction force from the vibration generation members is determined by the mass of the body portion 11 and the slider 32. The mass is chosen with no relation to the static load so that the mass is sufficiently heavy and the vibration energy is surely transmitted to the workpiece 100 from the cutter 13. Also, a vibration of the body portion 11 and the slider 12 caused by the vibration generation members is absorbed by using the magnetic force of paired magnets 41a, 41b and 42a, 42b without interposing a spring, and it is possible to keep resonance to a minimum. The workpiece 100 formed the scribe line as mentioned above is removed from the table 60 and is broken along the scribe line with a workpiece breaking apparatus not shown. It is to be noted that, in the above described embodiment, although a permanent magnet is used for the magnetically holding mechanism, an electromagnetic may be used for the magnetically holding mechanism. Using the electromagnet, the magnetically repelling force can be adjusted by changing an impressed electric current of the electromagnetic. Further, although the first pair of magnets 41a, 41b and second pair of magnets 42a, 42b are arranged parallel to the central axis L of the vibration generation members and shifted therefrom, the first pair of magnets 41a, 41b and second pair of magnets 42a, 42b may be arranged on the central axis L of the vibration generation members. Further, it may be possible to apply a pre-load to the vibration generation members by using a pair of magnets in place of the plate spring 6 and ball 30. Also, the scribing apparatus may be slanted in an angle of 90 degree so that the vibration generation members vibrate in a horizontal direction. In this case, gravity of the scribe body does not affect maintenance of the scribe body 10 by the paired magnets 41a, 41b and paired magnets 42a, 42b. Further, the cutter 13 may consists of a disk, capable of rotating, having a edge at a periphery thereof. Fig. 3 shows a scribing apparatus according to a second embodiment of the present invention. This scribing apparatus forms scribe line on a thin board-like workpiece 111 made of a hard brittle material such as plate glass, ceramics plates, a semicondutor or the like with a high speed and precision by using the cutter 112 such a a chisel or the like. After the cutter 112 contacts the workpiece 111 which is placed on the table 113, a pressure applied to the workpiece 111 by the cutter 112 is vibrated, consequently the vertical (longitudinal) cracks 114 are generated. The vertical cracks 114 will be applied a force so that the cracks 114 grows, and the workpiece 11 will be broken. As shown in Fig. 3, this scribing apparatus comprises a support body 115, a scribe body 117 having a cutter 112 and a vibration generation member 116 which vibrates the cutter periodically, a weight 118 applying a load to the scribe 117 so as to prevent the cutter 112 from floating up in the air, a pair of load applying magnets 119a, 119b, repulsing each other as a load transmission means for transmitting a load from the weight 118 to the scribe body 117 by using magnetic force, a pair of floatage applying magnets 120a, 120b repulsing each other which urge the scribe body 117 upwards as a static load adjustment device adjusting a static load applied to the workpiece 111 from the cutter 112 by using magnetic force. A linear rolling motion guide apparatus (a slide mechanism) such as rectilinear guide 121 is provided between the base plate 115 and the scribe body 117 so that the scribe body 117 is vertically movable in a rectilinear motion relative to the base plate 115. Also, a linear rolling motion guide apparatus (a slide mechanism) such as rectilinear guide 121 is provided between the support body 115 and the weight 118 so that the weight 118 is movable in a rectilinear motion relative to the base plate 115. The support body 115 is attached to a moving mechanism 123 so that the scribe body 117 and the weight 118 are horizontally movable in a two dimensions (horizontal plane). The scribe body 117 has the cutter 112 at a lower end thereof, and vibrates the cutter 112 periodically. Fig. 4 shows the scribe body 117. The scribe body 117 comprises the body portion 125, a holder 126 for holding the cutter 112 supported by the body portion 125 so as to be minutely slidable in a vertical direction, the cutter 112 (see Fig. 3) attached to the lower end of the holder 12 and two piezo-actuators 127, 127 in series or the like for generating and applying vibrations to the holder 12 in the vertical direction as a vibration generation member. The body portion 125, the holder 126, and the piezo-actuators 127, 127 have the same central line L, and in this embodiment the central line L is in a vertical direction. Applying a high frequency electric field to the piezo-actuators 127, 127 not only expands and contacts the piezo-actuators 127, 127 but also vibrates the cutter 112. These piezo-actuators 127, 127 are combined up and down in series and cooled by cooling air. The body portion 125 has a vertically elongated box-shaped structure, and the holder 126 is accommodated inside the body portion 11. The holder 126 also has a vertically elongated box-shaped structure, and the piezo-actuators 127, 127 are accommodated inside the holder 126. Projector 128 projecting into the inside of the body portion 125 is provided at an upper end portion of the body portion 125, on the other hand a hole 128 in which the projection 128 fit is made in a upper end portion of the holder 126. A spherical ball 130 which apply a pre-load to the piezo-actuators 127, 127 is provided at a lower end of the holder 126. This ball 130 is made of an elastic material such as rubber or resin or the like, and supported by a receiver plate 131. Also a plate spring 132 is disposed over the ball 130 laid across the body portion 125. The ball 130 and the plate spring 132 act to urge the piezo-actuators 127, 127 upward by their elastic restoring force. The pre-load applied to the piezo-actuators 127, 127 is adjusted by rotating a adjustment screw 133 provided at a upper end portion of the body portion 125. It is to be noted that, although the plate spring 132 and the ball 130 are used for applying the pre-load to the piezo-actuators 127, 127, it may be possible to use a pair of magnets to apply the pre-load to the piezo-actuators 127, 127. Further, it is not limited to the piezo-actuators 127, 127 made of piezoelectric materials for vibrating the cutter 112, and an actuator which vibrates by using the air or applying a magnetic field thereto may be used in place of the piezo-actuators 127, 127. The holder 126 has a pair of lower forked extensions extending so as to straddle the plate spring 132. As shown in Fig. 3 the cutter 112 is mounted to the lower end of the paired extensions of the holder 126 through attachments 134a, 134b so that a mounting angle of the cutter 112 is adjustable with respect to the holder 126. The lower attachment 134b is capable of turning against the upper attachments 134a, and the mounting angle of the lower attachment 134b is adjustable with respect to the upper attachment 134a. The cutter 112 is disposed on the central line L. A lower end portion of the cutter 112 has a conical shape extending downward and is sharp-pointed. The cutter 112 comprises a diamond particle having a substantially quadrangular pyramid shape fixed to the lower end thereof. The apex of the diamond particle points below so as to be put on the surface of the workpiece 111. It may be possible to use a disk-shaped chisel having an edge at a periphery thereof, and supported by a holder 126 with the chisel rotating. The weight 118 applying a load to the scribe body 117 comprises a mass changing device which changes mass of the weight 118. This mass changing device is composed of an additional weight 136 which is added by means such as bolts or adhesive for connecting the additional weight 136 to the weight 118. Mass of the additional weight 136 is determined corresponding to the workpiece 111. Also, if the mass of the scribe body 117 is wanted to be changed, an additional weight not shown is added by means such as bolts or adhesive. The mass of the additional weight for the scribe body 117 is also determined corresponding to the workpiece 111. As shown in Fig. 3, a plate spring 140 is provided under the lower end of the weight 118. Fig. 6 shows the plate spring 140 attached to the weight 118. A hollow 141 is formed on the lower end of the weight 118, and is laid across both edges 142, 142 so that the plate spring 140 is capable of deflecting. And at the center of a lower surface of the plate spring 140, a load applying magnet 119a mentioned later is attached. The scribe body 117 and the weight 118 is attached to the base plate 115 through the rectilinear guides 121, 122. Fig. 7 shows the rectilinear guides 121, 122. This rectilinear guides 121, 122 respectively comprises a guide rail 162 elongated and extending in a vertical direction formed with a ball rolling groove 161a extending along a longitudinal direction thereof, a movable block 165 formed with a ball circulation passage 164 including a loaded ball rolling groove 163a corresponding to the ball rolling groove 161a of the guide rail 162 and assembled with the guide rail 162 to be relatively movable along the guide rail 162, and a number of balls 166, arranged in a ball circulation passage 164 and circulating therein in conformity with the relative motion of the movable block 165 with respect to the guide rail 162. By arranging the number of balls 166, between the movable block 165 and the guide rail 162, the movable block 165 moves smoothly. The guide rail 162 is attached to the support body 115, and the movable block 165 is attached to the scribe body 117 or to the weight 118. The movable block 165 constitutes a part of the scribe body 117 or the weight 118 and contributes to mass of the scribe body 117 or the weight 118. A direction in which the weight 118 rectilinearly moves is consistent with a direction in which the scribe body 117 rectilinearly moves. It is to be noted that rollers may be used in place of the balls 166. As shown in Fig. 3, the pair of load applying magnets 119a, 119b as the load transmission means which transmits a load to the scribe body from the weight 118 by using magnetic force are disposed between the scribe body 117 and the weight 118. This pair of magnets respectively are composed of permanent magnet. One of the load applying magnets 119a, 119b is attached to the lower surface of the plate spring 140, and the other of the load applying magnets 119a, 119b is attached to the upper surface of the scribe body 117. Also, the pair of the load applying magnets 119a, 119b are vertically arranged in series opposing to each other so that identical magnetic polarities (for example N polarities) are put face to face. The pair of the load applying magnets 119a, 119b magnets are repulsing each other. Repulsive force caused by the load applying magnets 119a, 119b transmits the load of the weight 118 to the scribe body 117. The pair of upwards urging magnets 120a, 120b as the static load adjustment device which adjusts a static load applied to the workpiece 111 from the cutter 112 are provided under the scribe body 117. The pair of floatage applying magnets 120a, 120b are respectively composed of a permanent magnet. And one of the floating applying magnets 120a, 120b is attached to the lower surface of the scribe body 117 and the other is attached to a level controlling mechanism 146 which is provided in a horizontally extending plate 145 projecting from the support body 115. This level of controlling mechanism 146 has the same structure as a well-known micrometer and comprises a sleeve 147 fixed to a lower surface of the horizontally extending plate 149, a manually operated case 148 provided outside the sleeve 147, and a spindle 149 which projects upward from the sleeve 45a by rotating the manually operated case 148. The spindle 149 penetrates the horizontally extending plate 145 and extends upwards. The floatage applying magnet 120b is fixed to a upper end surface of the spindle 149. Rotating the manually operated case 148 adjust a projection amount of the spindle 149 and adjust a height of the floatage applying magnet 120b. The pair of upwards urging magnets 120a, 120b are also vertically arranged in series so that identical magnet polarities (for example N polarities) are put face to face with repulsing each other. Repulsive force of the floatage applying magnets 120a, 120 applies a floatage to the scribe body 117 and adjusts a static load applied to the workpiece 111 from the cutter 112. Also, an electromagnet which is capable of changing a magnetic force may be used in place of the permanent magnet. In case of using the electromagnet, magnetic force is adjusted by changing a voltage applied to the electromagnet. Next, how to use the scribe apparatus is explained hereinafter. First mass of the weight 118 and the scribe body 117 are determined according to a material of the workpiece 111 such as gallium arsenide (GaAs), or glass, or silicon, or the like and a thickness of the workpiece 111. The more heavier mass of the scribe body 117 is, the more larger the dynamic load is, and it is possible to form a deep vertical cracks 114 on the surface 111 a or the workpiece 111. Also, since gravity of the weight 118 and gravity of the scribe body added up influence the static load, it has been definite in advance according to the workpiece 111. Next, workpiece 111 is placed on the horizontal table 113, and the workpiece 111 is located in an appointed position. When the cutter 112 gets on the workpiece 111, the static load is applied to the workpiece 111 by the cutter 112. The height of the floatage applying magnet 120b is adjusted by the level controlling mechanism 146 so that the static load becomes definite according the workpiece 111. Suppose that the floatage applying magnets 120a, 120b are not provided, the static load is equal to the gravity of the weight 118 and the scribe body 117 added up. Providing the floatage applying magnets 120a, 120b decreases the static load by the magnetically repulsive force. If the static load is too large, a horizontal cracks may be generated on the surface 111 a of the workpiece 111. Conversely, if the static load is too small, the cutter 112 will float up from workpiece 111 in the air and have a collision with the workpiece 111 and cause damage to the workpiece 111. Therefore, the static load is carefully determined according to the workpiece 111. After gaining the definite static load, the piezo-actuators 127, 127 are applied a high frequency voltage (an electric field) and are periodically expanded or contracted in the axial direction. And the workpiece 111 is applied the dynamic load by vibrating the cutter 112. It is to be noted that since the cutter 112 is always contact with the workpiece 111 by the static load, the scribe body 117 itself vibrates. Fig. 8 shows a pressure applied to the workpiece 111 by the cutter 112. The pressure vibrates according to the vibration of the scribe body 117. And the mean value of the pressure is the same as the static load. The dynamic load, that is, an amplitude of vibration shown in Fig. 8 is in proportion to the mass of the scribe body 117 (to be exact, the mass of body portion and slide member 165). According to this embodiment of the invention, since the weight 118 floated by using the repulsive force of the load applying magnets 119a, 119b vibrates periodically, an interval between the pair of load applying magnets 119a, 119b seldom changes. Therefore the repulsive force of the load magnets 119a, 119b seldom changes. Further, since the magnets 119a, 119b are good in attenuation, an attenuation force is applied in the scribe body 117. As a result, it is possible to apply an appropriate dynamic load to the workpiece 111 by the cutter 112. Also, since a spring connecting the weight 118 with the scribe body 117 directly is not provided, the weight 118 will not resonate. Further, when the cutter runs on the workpiece 111, or a thickness of the workpiece 111 has changed, or the workpiece 111 is undulated, since the weight 118 moves and follows the cutter 112, magnetically repelling the force seldom changes in these cases. According to this embodiment of the invention, since the spring 140 and the load applying magnets 119a, 119b are connected in series, the vibration of the scribe body 117 will be complex, and it will be possible to apply a complex dynamic load vibrating to the workpiece 111 from the cutter 112. Therefore, deep vertical cracks can be formed even on the materials such as silicon and so forth that are difficult to be formed a scribe line with a sine wave. According to this embodiment of the invention, since the scribing apparatus comprises the static load adjustment device adjusting a static load applied to the workpiece 111 from the cutter 112, it is possible to lower the static load with the mass of the scribe body remaining heavy. Therefore, it is possible to lower the static load with the dynamic load remaining large, and to provide a scribe apparatus which is fitted to cut the hard brittle material. The support body 115 is horizontally moved by the moving mechanism 123. And the scribe line being composed of vertical cracks formed on the surface 111 a of the workpiece 111. The workpiece 111 formed the scribe line as mentioned above is removed from the table 113 and is broken along the scribe line with a workpiece breaking apparatus not shown. In one preferred example performed by the applicant, the scribe apparatus of a second embodiment was used. In the test result, the vertical cracks formed by the scribe apparatus was about 500 µm exceedingly deep to about 7 µm wide. Additionally it was confirmed that the surface 111a of the workpiece 111 was not damaged.

Claims: A scribing apparatus for scribing a line on the surface of a workpiece (100;111), the apparatus comprising: a scribe body (10;117) having a cutter (13;112) and a vibration generation member (14;116) arranged to periodically vibrate the cutter in use in a direction substantially perpendicular to the surface of the workpiece; a support device having a support body (20;115) and movable, in use, parallel to the surface of the workpiece; wherein the scribe body is movable, in use, relative to the support body in a direction perpendicular to the surface of the workpiece; characterised by comprising: a magnetic force applying means (40) associated with the support body and the scribe body arranged to apply, in use, a holding magnetic force to the scribe body in a direction perpendicular to the surface of the workpiece to hold, in use, the scribe body in a predetermined position relative to the support body. A scribing apparatus according to claim 1, wherein said magnetic force applying means (40) includes at least one pair of magnets (41;42) disposed between the scribe body (10;117) and the support body (20;115) and arranged to repel each other in use. A scribing apparatus according to claim 2, wherein said magnetic force applying means (40) comprises two pairs of magnets (41,42;119,120) disposed in the direction parallel to the direction in which the vibration generation member (14;116) vibrates. A scribing apparatus according to claim 3, wherein said magnetic force applying means (40) comprises: a first pair of magnets (41;119) arranged to repel each other, in use, one of said first pair of magnets being disposed on the scribe body (10;117) and the other one of said first pair of magnets being disposed on the support body so that a first repelling force is applied to the scribe body in use, and a second pair of magnets (42;120) arranged to repel each other in use, one of said second pair of magnets being disposed on the scribe body and the other one of said second pair of magnets being disposed on the support body so that a second repelling force is applied to the scribe body in use; wherein the first and second repelling forces are opposing each other and in a direction parallel to the direction in which the vibration generation member (14;116) vibrates. A scribing apparatus according to any of claims 2 to 4, wherein said magnetic force applying means (40) includes a magnetic force adjustment mechanism capable of adjusting, in use, the position of at least one of the pair of magnets (41,42;119,120). A scribing apparatus according to any of claims 2 to 4, wherein one of the pair of magnets (41,42;119,120) comprises an electromagnet, and said magnetic force applying means has a magnetic force adjustment mechanism capable of adjusting, in use, the impressed electric current of said electromagnet. A scribing apparatus according to any preceding claim, the support device further having: a weight (118) arranged to apply, in use, a load to the scribe body, (117) the weight being movable in the direction parallel to the direction in which the vibration generation member (116) vibrates; wherein the magnetic force applying means (40) is arranged to transmit, in use, the load to the scribe body from the weight. A scribing apparatus according to claim 7, wherein a spring (140,132) is disposed between said weight (118) and said magnetic force applying means (40) or between said magnetic force applying means and said scribe body (117). A scribing apparatus according to claim 8, wherein said spring comprises a flat spring (140) attached to the weight (118). A scribing apparatus according to any of claims 7 to 9 wherein, said weight (118) is also suppported by the support body (114) and wherein said scribe body (117) and said weight are attached to the support body through rectilinear guides (121,122) so that said scribe body and said weight are movable, in use, in the direction parallel to the direction in which the vibration generation member (116) vibrates. A scribing apparatus according to any of claims 7 to 10, further comprising a mass changing device (136) arranged to change, in use, the mass of said weight or said scribe body (117). A scribing apparatus according to any of claims 1 to 6, the support device further having: an elastic member arranged to apply, in use, a load to the scribe body (10,117) to urge it towards the workpiece; wherein the magnetic force applying means (40) is arranged to transmit, in use, the load from the elastic member to the scribe body.

Inventors: ISHIKAWA HIROKAZU, SHIMOTOYODOME GYO, ISHIKAWA, HIROKAZU, SHIMOTOYODOME, GYO
Applicants: BELDEX CORP, THK CO LTD, BELDEX CORPORATION, THK CO., LTD.
Application year: 2000
Main classification: C03B33
IPC codes: C03B33