Arrangement for mechanically and accurately processing a workpiece with a position detecting pattern or patterns

• US 4,794,736 A
• Filed: 03/08/1988
• Issued: 01/03/1989
• Est. Priority Date: 12/27/1985
• Status: Expired due to Term

• Current Assignee: Citizen Watch Co Limited (Citizen Electronics Company Limited)
• Original Assignee: Citizen Watch Co Limited (Citizen Electronics Company Limited)
• Inventors: Fujii, Naoki, Nakaoka, Junichi, Hatsuse, Toshikazu, Ito, Masaru, Wada, Toshiaki, Fuwa, Shigehiro
• Primary Examiner(s): Schmidt, Frederick R.
• Assistant Examiner(s): Rachuba, Maurina
• Application Number:
  US07/168,540
• Time in Patent Office: 301 Days
• Field of Search: 51/165.72, 51/165.77, 125/13 R, 83/71, 83/74, 83/365
• US Class Current: 451/6
• CPC Class Codes: B23Q 15/24 of linear position
• CPC Class Codes: B24B 49/12 involving optical means
• CPC Class Codes: B24B 9/065 of thin, brittle parts, e.g. semiconductors, wafers
• CPC Class Codes: G05B 19/402 characterised by control arrangements for positioning, e.g. centring a tool relative to a hole in the workpiece, additional detection means to correct position G05B19/19 takes precedence
• CPC Class Codes: G05B 2219/37572 Camera, tv, vision
• CPC Class Codes: G05B 2219/41091 Alignment, zeroing, nulling, set parallel to axis
• CPC Class Codes: G05B 2219/45161 Grinding machine

Abstract

An arrangement for mechanically processing a workpiece having a position detecting pattern or patterns formed thereon has a mechanically processing tool disposed at a predetermined position, a worktable arranged so as to be linearly moved in at least one of the rectangular coordinate X- and Y-axes while holding the workpiece thereon, and a position aligning unit provided with an opto-electric line sensor capable of detecting one of the patterns of the workpiece and issuing pattern detected signals, and an operation/control unit capable of mathematically processing the detected signals from the line sensor to determine a position of the workpiece to be mechanically processed and generating control signals for controlling the movement of the worktable so that the position to be mechanically processed is aligned with the position of the mechanically processing tool. The line sensor may be a CCD type line sensor.

Claims

1. An arrangement for mechanically processing a workpiece having at least one optically sensible position detection pattern formed thereon against which a desired position of the workpiece to be mechanically processed is established, comprising:

a worktable for mounting a workpiece thereon, arranged to be linearly movable in at least one axial direction of X- and Yperpendicular coordinate axes extending in a plane;

drive means including a table drive means for linearly moving said worktable in accordance with drive control information;

a machining tool for effecting a mechanical processing of the workpiece mounted on said worktable when the desired position of the workpiece is moved to and positioned at a predetermined position suitable for engagement with said machining tool;

a tool carrier carrying said machining tool and provided with a tool feed means for engaging said machine tool with said workpiece when carrying out the mechanical processing of said workpiece;

a position aligning system responsive to at least one position detecting pattern having a latent reference line and at least one side line inclined relative to one of the X and Y coordinate axis at a predetermined angle for carrying out a position alignment of said desired position of said workpiece with said predetermined position suitable for engagement with said machine tool, said position aligning system including;

a position detector arranged at a fixed position with respect to said machining tool, and having an opto-electric line sensor including means for issuing an electrical signal indicating a linear amount of displacement of said position detecting pattern of said workpiece in at least one axial direction of said X- and Y-coordinate axes by scanning said position detecting pattern in a predetermined single axial direction of said X- and Y-coordinate axes when said workpiece mounted on said worktable is positioned beneath said position detector, and;

operation and control means connected to said position detector for carrying out a mathematical operation to detect the latent reference line of said position detecting pattern and said desired position of said workpiece to be mechanically processed in accordance with said electrical signal from said position detector, said operation and control means being further connected to said table drive means for providing said table drive means with said drive control information for moving said worktable until said desired position of said workpiece to be mechanically processed is aligned with said predetermined position suitable for engagement with said machine tool.

2. An arrangement for mechanically processing a workpiece according to claim 1, wherein said worktable is arranged so as to be moved in both directions of the X- and Y-perpendicular coordinate axes by said table drive means of said drive means, and wherein said tool carrier is non-movably arranged so as to hold said machining tool at a fixed position with respect to said X- and Y-perpendicular coordinate axes, said tool carrier being formed so as to be mechanically integral with said position detector of said position aligning system.

3. An arrangement for mechanically processing a workpiece according to claim 2, wherein said worktable is arranged so as to be further rotatable about an axis vertical to the plane of the X- and Y-perpendicular coordinate axes, wherein said drive means includes a table rotating means for rotating said worktable about said axis vertical to the plane of the X- and Y-perpendicular coordinate axes in accordance with rotation control information, and wherein said operation and control means is connected to said table rotating means and is able to further carry out a mathematical operation to detect an angular displacement of said latent reference line of said position detecting pattern with respect to the X- and Y-perpendicular coordinate axes, thereby providing said table rotating means with said rotation control information until said angular displacement of said latent reference line of said position detecting pattern is eliminated.

4. An arrangement for mechanically processing a workpiece according to claim 1, wherein said worktable is linearly movable in a first axial direction of the X- and Y-coordinate axes by said table drive means of said drive means, and wherein said tool carrier carrying said machining tool is movable in a second axial direction perpendicular to the first axial direction in the plane of the X- and Y-coordinate axes and is also formed so as to be mechanically integral with said position detector of said position aligning system, and wherein said drive means includes a tool carrier drive means for linearly moving said tool carrier in the second axial direction.

5. An arrangement for mechanically processing a workpiece according to claim 1, wherein said operation and control means comprises a first means for mathematically calculating a positional difference between said desired position of said workpiece to be mechanically processed and an actually processed position of said workpiece detected by said opto-electric line sensor after completion of a preceding one of every two successive mechanical processing operations of said workpiece, and a second means for generating a feedback drive information on the basis of said positional difference calculatd by said first means and for supplying said feedback drive information to said table drive means of said drive means prior to commencement of the remaining one of said every two successive mechanical processing operations of said workpiece.

6. An arrangement for mechanically processing a workpiece according to claim 1, wherein said machining tool is a severing wheel rotationally driven by a drive motor held in said tool carrier for severing said workpiece.

7. An arrangement for mechanically processing a workpiece according to claim 1, wherein said opto-electric line sensor is a CCD linear image sensor.

11. An arrangement for mechanically processing a workpiece as in claim 1, wherein the means for determining the linear displacement of said position detecting pattern from said at least one coordinate axis includes means for determining the product of

(a) a number of clock pulses corresponding to the position of said at least one side line from said at least one coordinate axis, and

(b) a constant corresponding to the size of each line sensor, and

(c) The tangent of the angle of inclination of said at least one side line to said single coordinate axis.

8. An apparatus for severing a workpiece having at least one optically sensible position detecting pattern formed thereon against which a desired severed position of the workpiece is established, comprising:

a fixed machine bed;

a worktable for mounting a workpiece thereon, arranged on the fixed machine bed so as to be linearly movable in at least one axial direction of the X- and Y-perpendicular coordinate axes extending in a horizontal plane;

table drive means for linearly moving said worktable in accordance with drive control information, said table drive means including at least a drive motor for drive linear movement of said worktable via a feed mechanism, and a drive circuit connected to said drive motor;

a rotatable abrasive wheel for severing at the desired severing position of said workpiece mounted on said worktable when said desired position of said workpiece is moved to and positioned at a predetermined position suitable for engagement with a severing edge of said abrasive wheel;

a tool carrier arranged on said fixed machine bed at a position spaced from said worktable and carrying said abrasive wheel, said tool carrier being provided with a tool feed means for engaging said abrasive wheel with said workpiece when severing said workpiece;

a position aligning system responsive to at least one position detecting pattern having a latent reference line and at least one side line inclined relative to one of the X and Y coordinate axes at a predetermined angle for carrying out a position alignment of said desired severing position of said workpiece with said predetermined position suitable for engagement with said abrasive wheel, said position aligning system including;

a position detector arranged above said worktable while maintaining a fixed positional relationship with respect to said abrasive wheel, said position detector having a CCD type line sensor having means for issuing an electrical signal indicating a linear amount of displacement of said position detecting pattern of said workpiece in at least one axial direction of said X- and Y-coordinate axes by scanning said position detecting pattern in a predetermined single axial direction of said X- and Y-coordinate axes when said workpiece mounted on said worktable is positioned directly beneath said position detector, and;

operation and control means electrically connected to said position detector for carrying out a mathematical operation to detect the latent reference line of said position detecting pattern and said desired severing position of said workpiece in accordance with said electrical signal from said position detector, said operation and control means being further electrically connected to said drive circuit for providing said table drive motor with said drive control information for moving said worktable until said desired severing position of said workpiece is aligned with said predetermined position suitable for engagement with said abrasive wheel.

9. An apparatus for severing a workpiece according to claim 8, wherein said workpiece is a semiconductor wafer having said position detecting pattern, for being severed into a plurality of semiconductor chips.

10. An apparatus for severing a workpiece according to claim 9, wherein said position detecting pattern is trapezoidal in configuration having a latent center line forming said latent reference line and arranged so that said latent center line extends parallel to one of the axial directions of the X- and Y-perpendicular coordinate axes extending in a horizontal plane.

12. An apparatus for severing a workpiece as in claim 8, wherein the means for determining the linear displacement of said position detecting pattern from said at least one coordinate axis includes means for determining the product of

(a) a number of clock pulses corresponding to the position of said at least one side line from said at least one coordinate axis, and

(b) a constant corresponding to the size of each line sensor, and

(c) The tangent of the angle of inclination of said at least one side line to said single coordinate axis.

13. An arrangement for mechanically processing a workpiece having at least one optically sensible position detection pattern formed thereon against which a desired position of the workpiece to be mechanically processed is established, comprising:

a worktable for mounting a workpiece thereon, arranged to be linearly movable in at least one axial direction of X- and Y-perpendicular coordinate axes extending in a plane;

drive means including a table drive means for linearly moving said worktable in accordance with drive control information;

a machining tool for effecting a mechanical processing of the workpiece mounted on said worktable when the desired position of the workpiece is moved to and positioned at a predetermined position suitable for engagement with said machining tool;

a tool carrier carrying said machining tool and provided with a tool feed means for engaging said machine tool with said workpiece when carrying out the mechanical processing of said workpiece;

a position aligning system responsive to a position detecting pattern having a first rectangle, a second rectangle parallel to and spaced a predetermined to distance from one side of the first rectangle, and a third rectangle parallel to and spaced a predetermined distance from the opposite side of the first rectangle, said pattern having a latent reference line parallel to said first, second and third spaced rectangles, for carrying out a position alignment of said desired position of said workpiece with said predetermined position suitable for engagement with said machine tool, said position aligning system including;

a position detector arranged at a fixed position with respect to said machining tool, and having an opto-electric line sensor including means for issuing an electrical signal indicating a linear amount of displacement of said position detecting pattern of said workpiece in at least one axial direction of said X- and Y-coordinate axes by scanning said position detecting pattern in a predetermined single axial direction of said X- and Y-coordinate axes when said workpiece mounted on said worktable is positioned beneath said position detector, and;

operation and control means connected to said position detector for carrying out a mathematical operation to detect the latent reference line of said position detecting pattern and said desired position of said workpiece to be mechanically processed in accordance with said electrical signal from said position detector, said operation and control means being further connected to said table drive means for providing said table drive means with said drive control information for moving said worktable until said desired position of said workpiece to be mechanically processed is aligned with said predetermined position suitable for engagement with said machine tool.

15. An arrangement for mechanically processing a workpiece as in claim 13, wherein the means for determining the linear displacement of said position detecting pattern from said at least one coordinate axis includes means for determining the product of

(a) a number of clock pulses corresponding to the position of said at least one side line from said at least one coordinate axis, and

(b) a constant corresonding to the size of each line sensor, and

(c) The tangent of the angle of inclination of said at least one side line to said single coordinate axis.

14. An apparatus for severing a workpiece having at least one optically sensible position detecting pattern formed thereon against which a desired severed position of the workpiece is established, comprising:

a fixed machine bed;

a worktable for mounting a workpiece therein, arranged on the fixed machine bed so as to be linearly movable in at least one axial direction of the X- and Y-perpendicular coordinate axes extending in a horizontal plane;

table drive means for linearly moving said worktable in accordance with drive control information, said table drive means including at least a drive motor for drive linear movement of said worktable via a feed mechanism, and a drive circuit connected to said drive motor;

a rotatable abrasive wheel for severing at the desired severing position of said workpiece mounted on said worktable when said desired position of said workpiece is moved to and positioned at a predetermined position suitable for engagement with a severing edge of said abrasive wheel;

a tool carrier arranged on said fixed machine bed at a position spaced from said worktable and carrying said abrasive wheel, said tool carrier being provided with a tool feed means for engaging said abrasive wheel with said workpiece when severing said workpiece;

a position aligning system responsive to a position detecting pattern having a first rectangle, a second rectangle parallel to and spaced a predetermined to distance from one side of the first rectangle, and a third rectangle parallel to and spaced a predetermined distance from the opposite side of the first rectangle, said pattern having a latent reference line parallel to said first, second and third spaced rectangles, for carrying out a position alignment of said desired severing position of said workpiece with said predetermined position suitable for engagement with said abrasive wheel, said position aligning system including;

a position detector arranged above said worktable while maintaining a fixed positional relationship with respect to said abrasive wheel, said position detector having a CCD type line sensor having means for issuing an electrical signal indicating a linear amount of displacement of said position detecting pattern of said workpiece in at least one axial direction of said X- and Y-coordinate axes by scanning said position detecting pattern in a predetermined single axial direction of said X- and Ycoordinate axes when said workpiece mounted on said worktable is positioned directly beneath said position detector, and;

operation and control means electrically connected to said position detector for carrying out a mathematical operation to detect the latent reference line of said position detecting pattern and said desired severing position of said workpiece in accordance with said electrical signal from said position detector, said operation and control means being further electrically connected to said drive circuit for providing said table drive motor with said drive control information for moving said worktable until said desired severing position of said workpiece is aligned with said predetermined position suitable for engagement with said abrasive wheel.

16. An apparatus for severing a workpiece as in claim 14, wherein the means for determining the linear displacement of said position detecting pattern from said at least one coordinate axis includes means for determining the product of

(a) a number of clock pulses corresponding to the position of said at least one side line from said at least one coordinate axis, and

(b) a constant corresponding to the size of each line sensor, and

(c) The tangent of the angle of inclination of said at least one side line to said single coordinate axis.