Non-contact high resolution displacement measurement technique
First Claim
1. Apparatus for at least partially determining a coordinate position at which an edge of a workpiece intersects a sensing plane, the sensing plane containing a z-axis, the apparatus comprising:
- source means for emitting energy from a source region intersecting the sensing plane, the energy striking the edge such that the edge creates a shadow having a first penumbra having a non-zero z-dimension, the first penumbra having an intensity-of-shadow which varies in the z-dimension,first detection means for detecting the amount of energy which reaches a first known detection region which lies wholly within the first penumbra, the first known detection region intersecting the sensing plane and having a non-zero z-dimension where it intersects the sensing plane; and
means for determining a first relationship between the coordinate positions of the edge in the sensing plane in response to the first detection means.
4 Assignments
0 Petitions
Accused Products
Abstract
Apparatus is disclosed for optically detecting the position of an edge of a workpiece (such as an IC lead tip) in a sensing plane, involving the emission of electromagnetic energy from a known source region in the sensing plane such as to cause the edge to create a shadow having a penumbra in the sensing plane. Two detectors determine the amount of energy which reach two known detection regions in the sensing plane and wholly within the penumbra. The amount of energy detected by one detector determines a first curve in the sensing plane on which the edge must lie, and the amount of energy detected by the other determines a second such curve. The intersection of these two curves fully determines the position of the edge in the sensing plane. Preferably, the source region and both detector regions are all essentially line segments oriented parallel to a z-axis, the two detection regions being disposed axially but spaced from each other. Apparatus is also disclosed for determining a profile of edges on one side of the workpiece. Algorithms are disclosed for interrelating measurements taken on four sides of the workpiece, calculating coplanarity of the lead tips, and calculating tweezing coplanarity of the leads. Two calibration methods are also disclosed. Further apparatus is disclosed for rotating a workpiece by 90 degrees, for example, in order to scan leads on different sides of a package, without requiring any physical modifications for workpieces of different sizes.
51 Citations
79 Claims
-
1. Apparatus for at least partially determining a coordinate position at which an edge of a workpiece intersects a sensing plane, the sensing plane containing a z-axis, the apparatus comprising:
-
source means for emitting energy from a source region intersecting the sensing plane, the energy striking the edge such that the edge creates a shadow having a first penumbra having a non-zero z-dimension, the first penumbra having an intensity-of-shadow which varies in the z-dimension, first detection means for detecting the amount of energy which reaches a first known detection region which lies wholly within the first penumbra, the first known detection region intersecting the sensing plane and having a non-zero z-dimension where it intersects the sensing plane; and means for determining a first relationship between the coordinate positions of the edge in the sensing plane in response to the first detection means. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
-
8. Apparatus for determining the position in which an edge of a workpiece intersects a sensing plane parallel to a z-axis, the apparatus comprising:
-
source means for emitting energy from a source region intersecting the sensing plane, the energy striking the edge such that the edge creates a shadow having a first penumbra, the first penumbra having an intensity-of-shadow which varies in the z-dimension; first detection means for detecting the amount of energy which reaches a first known detection region in the first penumbra, the first known detection region intersecting the sensing plane and having a non-zero z-dimension where it intersects the sensing plane; and second detection means for detecting the amount of energy which reaches a second known detection region in the first penumbra, the second known detection region intersecting the sensing plane and having a non-zero z-dimension where it intersects the sensing plane. - View Dependent Claims (9)
-
-
10. Apparatus for inspecting a protrusion on a workpiece, the protrusion having opposing first and second edges, the apparatus comprising:
-
source means for emitting electromagnetic energy onto the first and second edges such that the first edge creates a shadow having a first penumbra having a non-zero size in a dimension perpendicular to the first edge, and such that the second edge creates a shadow having a second penumbra having a non-zero size in a dimension perpendicular to the second edge; first detection means for detecting the amount of energy which reaches a first known detection region in the first penumbra; and second detection means for detecting the amount of energy which reaches a second known detection region in the second penumbra.
-
-
11. Apparatus for inspecting a workpiece, the workpiece having an edge, the apparatus being associated with a coordinate system having an origin and mutually perpendicular, x, y and z axes extending from the origin, the apparatus being further associated with a sensing plane parallel to the y-z plane, the apparatus comprising:
-
source means for emitting energy from a known source region, the known source region having a non-zero z-dimension and being no wider in the x-dimension than a desired width, the source region consisting of a set of source points; means for staging the workpiece such that the edge passes through the sensing plane and blocks part of the energy emitted from the known source region to thereby create a shadow having a penumbra indicative of the y-z coordinate position of the edge, the penumbra having an intensity-of-shadow which varies at least in the z-dimension; and means for outputting a first signal indicative of the amount of energy which reaches a first known detection region in the penumbra from the source means. - View Dependent Claims (12, 13, 14, 15, 16, 17)
-
-
18. Apparatus for inspecting a workpiece, the workpiece having a first side surface and a base surface, the workpiece having a plurality of edges including a first body edge at a meeting between the first side surface and the base surface, the plurality of edges further including a subject edge, the apparatus being associated with a coordinate system having an origin and mutually perpendicular x, y and z axes extending from the origin, the apparatus being further associated with a sensing plane parallel to the y-z plane, the apparatus comprising:
-
source means for emitting energy from a known source region, the known source region having a non-zero z-dimension and being no wider in the x-dimension than a desired width, the source region consisting of a set of source points; means for staging the workpiece such that the subject edge passes through the sensing plane and blocks part of the energy emitted from the known source region to thereby create a shadow having a penumbra indicative of the position of the subject edge, the penumbra having an intensity-of-shadow which varies at least in the z-dimension; means for outputting a first signal indicative of the amount of energy which reaches a first known detection region in the penumbra from the source means, the first known detection region consisting of a first set of detection points; and means for outputting a second signal indicative of the amount of energy which reaches a second known detection region in the penumbra from the source means, the second known detection region consisting of a second set of detection points; and means for determining the z coordinate of the point where the subject edge passes through the sensing plane, including means for calculating values of constants in a formula obtained by solving substantially the two simultaneous equations defined by (1) an integration of the estimated effect on the first signal which would be caused by the incidence on each detection point in the first set of detection points of energy from each source point in the set of source points which would reach such detection point in the first set of detection points if the subject edge is at an arbitrary y-z position, and by (2) an integration of the estimated effect on the second signal which would be caused by the incidence on each detection point in the second set of detection points of energy from each source point in the set of source points which would reach such detection point in the second set of detection points if the subject edge is at the arbitrary y-z position. - View Dependent Claims (19, 20, 21)
-
-
22. Apparatus for determining an edge profile of edges on a side of a workpiece, the apparatus having associated therewith an x-y-z Cartesian coordinate system, the apparatus comprising:
-
source means for emitting energy from a known source region, the known source region having a non-zero z-dimension and including a source point; staging means for staging the workpiece such that one of the edges blocks part of the energy emitted by the source means to thereby create a shadow having a penumbra with an intensity-of-shadow which varies in the z-dimension. first detection means for detecting the amount of energy emitted from the known source region which reaches a first known detection region in the penumbra, the first known detection region including a first detection point; and moving means for relatively moving the workpiece with respect to the first known detection region in a direction not substantially parallel to any plane which is parallel to the z-axis and which passes through both a point in the known source region and a point in the first known detection region. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29)
-
-
30. Apparatus for rotating by a given angle in a given direction about an axis of rotation a substantially rectangular workpiece of arbitrary size, the workpiece having a first side and a second side adjacent to the first side, the apparatus comprising:
-
means for positioning the workpiece such that the first side lies on a first line spaced from the axis by a first distance and the second side lies on a second line spaced from the axis by a second distance; and means for rotating the positioned workpiece by the given angle in the given direction about the axis; wherein the first and second distances remain fixed for different sizes of workpieces. - View Dependent Claims (31, 32, 33)
-
-
34. Apparatus for rotating a substantially rectangular workpiece of arbitrary size by 90°
- , the workpiece having a first side and a second side adjacent to the first side, for use in association with an input guide wall, an output guide wall, first means for moving the workpiece along the input guide wall while the first side remains substantially against the input guide wall, the first means for moving stopping when the second side reaches a second line, and second means for moving the workpiece along the output guide wall while the second side remains substantially against the output guide wall, the input guide wall and the output guide wall both lying substantially along a first line, the apparatus comprising;
a rotation table rotatable about an axis which is spaced from each of the first line and the second line by a distance which is fixed for different sizes of workpieces; and means for rotating the rotation table. - View Dependent Claims (35, 36, 37)
- , the workpiece having a first side and a second side adjacent to the first side, for use in association with an input guide wall, an output guide wall, first means for moving the workpiece along the input guide wall while the first side remains substantially against the input guide wall, the first means for moving stopping when the second side reaches a second line, and second means for moving the workpiece along the output guide wall while the second side remains substantially against the output guide wall, the input guide wall and the output guide wall both lying substantially along a first line, the apparatus comprising;
-
38. Apparatus for inspecting a workpiece, the workpiece having first, second, third and fourth side surfaces, the apparatus comprising:
-
first, second, third and fourth means for determining an edge profile of the edges on one side of the workpiece; first, second and third rotation means for rotating the workpiece by a predetermined angle in a predetermined direction, each rotation means having an axis of rotation; transport means for transporting the workpiece from the first means for determining an edge profile sequentially to the first rotation means, the second means for determining an edge profile, the second rotation means, the third means for determining an edge profile, the third rotation means and the fourth means for determining an edge profile; and means for performing inspection tests on the edge profiles determined by the first, second, third and fourth means for determining an edge profile. - View Dependent Claims (39, 40)
-
-
41. A method for use with apparatus for determining the y-z position of an edge passing through a sensing plane parallel to a y-z plane in an x-y-z Cartesian coordinate system, the apparatus comprising:
-
source means for emitting electromagnetic energy from a source region which is essentially a line segment extending in the sensing plane from the nominal positions (y,z)=(h,-a) to (y,z)=(h,a); first detection means for detecting the amount of energy received at a first known detection region which is essentially a line segment extending in the sensing plane from the nominal positions (y,z)=(0,zb1) to (y,z)=(0,zt1); second detection means for determining the amount of energy received at a second known detection region which is essentially a line segment extending in the sensing plane from the nominal positions (y,z)=(0,zb2) to (y,z)=(0,zt2); and means responsive to the first detection means and the second detection means for calculating an expected y-z position of the edge based on stored values of a, h, zb1, zt1, zb2 and zt2, the method comprising the steps of; reading for at least one known y-z position of a calibration edge the amount of energy detected by the first detection means and the amount of energy detected by the second detection means; setting up initial test values of the parameters a, h, zb1, zt1, zb2 and zt2 ; calculating expected position information of the calibration edge based on the read amounts of energy and the current test values of a, h, zb1, zt1, zb2 and zt2 ; determining an error between the expected position information and the at least one known y-z position of the calibration edge; repeating the steps of calculating and determining for predetermined numbers of permutations of test values of a, h, zb1, zt1, zb2 and zt2 ; and storing for subsequent use by the means for calculating the test values of a, h, zb1, zt1, zb2 and zt2 which were used in the calculating step and which yielded the smallest error in the determining step. - View Dependent Claims (42, 43)
-
-
44. A method for use with apparatus for determining position information about a first edge of a workpiece, the apparatus comprising:
-
source means for emitting energy from a known source region, the known source region having a non-zero z-dimension; first detection means for outputting a first signal nominally indicative of the amount of energy emitted from the source region which reaches a first known detection region; and means for calculating an apparent y-z position of the edge in response to the first signal, the method comprising the steps of; positioning a calibration edge at a first known y-z position; calculating for the current known y-z position of the calibration edge an expected value of the first signal; storing in relation to the nominal value of the first signal a correction term which when applied to the nominal value of the first signal will yield substantially the expected value of the first signal; moving the calibration edge to a known y-z position at which the first detection means outputs a signal different from that output for any previous y-z position of the calibration edge; and repeating for a desired number of repetitions the steps of calculating, storing and moving. - View Dependent Claims (45, 46, 47, 48, 49, 50)
-
-
51. Apparatus for inspecting a 4-sided workpiece, the workpiece including a body having a base surface, a first side surface, a second side surface adjacent to the first side surface, a third side surface adjacent to the second side surface and a fourth side surface joining the third and first side surfaces, the workpiece further including first, second, third and fourth body edges at meetings between the base surface and, respectively, the first, second, third and fourth side surfaces, the workpiece further including a first plurality of leads extending from the first side surface, a second plurality of leads extending from the second side surface, a third plurality of leads extending from the third side surface and a fourth plurality of leads extending from the fourth side surface, each lead having a lead tip, the apparatus comprising:
-
means for obtaining a first item of lead position information concerning at least one of the first plurality of leads, with reference to a first coordinate system, and obtaining the positions of at least two places on the first body edge with respect to the first coordinate system; means for obtaining a second item of lead position information concerning at least one of the second plurality of leads, with reference to a second coordinate system, and obtaining the positions of at least two points on the second body edge with respect to the second coordinate system; means for obtaining a third item of lead position information concerning at least one of the third plurality of leads, with reference to a third coordinate system, and obtaining the positions of at least two points on the third body edge with respect to the third coordinate system; means for obtaining a fourth item of lead position information concerning at least one of the fourth plurality of leads, with reference to a fourth coordinate system, and obtaining the positions of at least two points on the fourth body edge with respect to the fourth coordinate system; and means for interrelating the first, second, third and fourth items of lead position information substantially by applying to the first, second and third items of lead position information respective first, second and third transformations, the first, second and third transformations being such that, when applied respectively to the positions with respect to the first coordinate system of the at least two points on the first body edge, the positions with respect to the second coordinate system of the at least two points on the second body edge and the positions with respect to the third coordinate system of the at least two points on the third body edge, the transformations cause a first line drawn through the at least two points on the first body edge to intersect both a second line drawn through the at least two points on the second body edge and a fourth line drawn through the at least two points on the fourth body edge, cause a third line drawn through the at least two points on the third body edge to intersect both the second line and the fourth line, and cause the first, second, third and fourth lines to be coplanar.
-
-
52. Apparatus for testing the tweezing coplanarity of a four-sided IC package, the package including a body having a base surface, a first side surface, a second side surface adjacent to the first side surface, a third side surface adjacent to the second side surface, and a fourth side surface joining the third and first side surfaces, the package further including first, second, third and fourth body edges at meetings between the base surface and, respectively, the first, second, third and fourth side surfaces, the package further including a first plurality of leads extending from the first side surface, a second pluarality of leads extending from the second side surface, a third plurality of leads extending from the third side surface, and a fourth plurality of leads extending from the fourth side surface, each lead extending outward from the body in a direction nominally parallel to the base surface for a respective protrusion distance, then bending at a respective lead shoulder to pass through a base plane containing the base surface in a direction nominally perpendicular to the base plane, a first reference line being defined as the line passing through the lead shoulders of the two leads extending from the first side surface, which two leads have the largest protrusion distances of all the leads extending from the first side surface, a second reference line being defined as the line passing through the lead shoulders of the two leads extending from the second side surface, which two leads have the largest protrusion distances of all the leads extending from the second side surface, a third reference line being defined as the line passing through the lead shoulders of the two leads extending from the third side surface, which two leads have the largest protrusion distances of all the leads extending from the third side surface, a fourth reference line being defined as the line passing through the lead shoulders of the two leads extending from the fourth side surface, which two leads have the largest protrusion distances of all the leads extending from the fourth side surface, the apparatus comprising:
-
means for indicating a failure if the sum of the distance between the first reference line and the first body edge and the distance between the third reference line and the third body edge differs from a first constant by more than a tweezing coplanarity tolerance, both distances being taken along a projection into the base plane of any perpendicular to the first reference line, which projection intersects both the first body edge and the third body edge; and means for indicating a failure if the sum of the distance between the second reference line and the second body edge and the distance between the fourth reference line and the fourth body edge differs from a second constant by more than the tweezing coplanarity tolerance, both distances being taken along a projection into the base plane of any perpendicular to the second reference line, which projection intersects both the second body edge and the fourth body edge.
-
-
53. A method for determining a seating plane of the tips of N leads extending downward from a body, including at least three lead tips which are not all collinear, the method comprising the steps of:
-
(a) providing in a computer memory representations of a plane and the positions in space of the lead tips relative to each other and to the plane, the plane passing through a group of three of the lead tips, all others of the lead tips being either on the plane or on the same side of the plane as the body, the step of providing including a step of changing in the computer memory in a manner which corresponds to rotation, relative to the plane, of the body about a roll axis the representation of at least one member of the group consisting of the plane and the positions of the lead tips; and (b) while the projection of the center of gravity of the body onto the plane is outside the triangle defined by the group of three of the lead tips, repeating the step of; modifying in the computer memory in a manner which corresponds to rotation, relative to the plane, of the body about a new roll axis the representation of at least one member of the group consisting of the plane and the positions of the lead tips, until the plane passes through an additional lead tip, the additional lead tip being the lead tip which is first to touch the plane during such rotation, the new roll axis being defined as the line which contains a first line segment or a second line segment, whichever is between the most recent roll axis and substantially the projection onto the plane of the center of gravity of the body, the first line segment being defined by a first pair of the lead tips in the group of three of the lead tips and the second line segment being defined by a second pair of the lead tips in the group of three of the lead tips, the second pair being different from the first pair and neither the first pair nor the second pair defining any previous roll axis, the group of three of the lead tips being redefined after each repetition as the additional lead tip and the two of the lead tips in the group of three of the lead tips which are on the new roll axis. - View Dependent Claims (54, 55, 56, 57)
-
-
58. A method for use with apparatus for determining the y-z position of an edge passing through a sensing plane parallel to a y-z plane in an x-y-z coordinate system, the apparatus including a means for calculating such y-z position, and further including an original part and a spare part to replace the original part, the method comprising the steps of:
-
obtaining a first set of calibration data for the apparatus with the original part installed; obtaining a second set of calibration data for the apparatus with the spare part installed; and storing both the first and second sets of calibration data for subsequent use by the means for calculating, the means for calculating using the first set of calibration data when the original part is installed and using the second set of calibration data when the spare part is installed.
-
-
59. A method for use with apparatus for determining position information about a first edge of a workpiece, the apparatus comprising:
-
source means for emitting energy from a known source region, the known source region having a non-zero z-dimension; first detection means for outputting a first signal nominally indicative of the amount of energy emitted from the source region which reaches a first known detection region; second detection means for outputting a second signal nominally indicative of the amount of energy emitted from the source region which reaches a second known detection region; and means for calculating an apparent y-z position of the edge in response to the first and second signals, the method comprising the steps of; positioning a calibration edge at a first known y-z position; calculating for the current known y-z position of the calibration edge an expected value of the first signal; calculating for the current known y-z position of the calibration edge an expected value of the second signal; storing in relation to the nominal value of the first signal a first correction term which when applied to the nominal value of the first signal will yield substantially the expected value of the first signal; storing in relation to the nominal value of the second signal a second correction term which when applied to the nominal value of the second signal will yield substantially the expected value of the second signal; moving the calibration edge to a known y-z position at which the first detection means or the second detection means outputs a signal different from that output by the same detection means for any previous y-z position of the calibration edge; and repeating for a desired number of repetitions the steps of calculating, storing in relation to the nominal value of the first signal, storing in relation to the nominal value of the second signal and moving; wherein the step of storing in relation to the nominal value of the first signal comprises the step of storing in correspondence;
(a) the first correction term and (b) an index ratio Iread1 /(Iopen1 -Iclosed1), where Iread1 is the nominal value of the first signal for the current y-z position of the calibration edge, Iopen1 is the nominal value of the first signal when the calibration edge blocks none of the energy emitted from the source region from reaching the first detection region, and Iclosed1 is the nominal value of the first signal when the calibration edge blocks all of the energy emitted from the source region from reaching the first detection region directly, andwherein the step of storing in relation to the nominal value of the second signal comprises the step of storing in correspondence;
(a) the second correction term and (b) an index ratio Iread2 /(Iopen2 -Iclosed
2), where Iread2 is the nominal value of the second signal for the current y-z position of the calibration edge, Iopen2 is the nominal value of the second signal when the calibration edge blocks none of the energy emitted from the source region from reaching the second detection region, and Iclosed2 is the nominal value of the second signal when the calibration edge blocks all of the energy emitted from the source region from reaching the second detection region directly. - View Dependent Claims (60)
-
-
61. Apparatus for inspecting a workpiece, the workpiece having a first side surface and a base surface, the workpiece having a plurality of edges including a first body edge at a meeting between the first side surface and the base surface, the plurality of edges further inlcuding a subject edge, the apparatus being associated with a coordinate system having an origin and mutually perpendicular x, y and z axes extending from the origin, the apparatus being further associated with a sensing plane parallel to the y-z plane, the apparatus comprising:
-
source means for emitting energy from a known source region, the known source region having a non-zero z-dimension and being no wider in the x-dimension than a desired width, the source region consisting of a set of source points; means for staging the workpiece such that the subject edge passes through the sensing plane and blocks part of the energy emitted from the known source region to thereby create a shadow having a penumbra indicative of the position of the subject edge, the penumbra having an intensity-of-shadow which varies at least in the z-dimension; means for outputting a first signal indicative of the amount of energy which reaches a first known detection region in the penumbra from the source means, the first known detection region consisting of a first set of detection points; and means for outputting a second signal indicative of the amount of energy which reaches a second known detection region in the penumbra from the source means, the second known detection region consisting of a second set of detection points; and means for determining the y coordinate of the point where the subject edge passes through the sensing plane, including means for calculating values of constants in a formula obtained by solving substantially the two simultaneous equations defined by (1) an integration of the estimated effect on the first signal which would be caused by the incidence on each detection point in the first set of detection points of energy from each source point in the set of source points which would reach such detection point in the first set of detection points if the subject edge is at an arbitrary y-z position, and by (2) an integration of the estimated effect on the second signal which would be caused by the incidence on each detection point in the second set of detection points of energy from each source point in the set of source points which would reach such detection point in the second set of detection points if the subject edge is at the arbitrary y-z position. - View Dependent Claims (62)
-
-
63. A method for inspecting a workpiece having an edge, in apparatus associated with a coordinate system having mutually perpendicular x, y and z axes, said apparatus further having associated therewith a sensing plane parallel to the y-z plane, said method comprising the steps of:
-
staging said workpiece such that said edge intersects said sensing plane, said edge intersecting said sensing plane at an intersection point having y and z coordinates; emitting energy such that said edge creates a shadow having a grey region, said grey region having an intensity-of-shadow which varies in the z-dimension substantially according to a known function of said y and z coordinates; and determining from the amount of energy which reaches a first known detection region in said grey region a first relationship between said y and z coordinates. - View Dependent Claims (64, 65, 66, 67, 68)
-
-
69. A method for inspecting a workpiece having an edge, in apparatus associated with a coordinate system having mutually perpendicular x, y and z axes, said apparatus further having associated therewith a sensing plane parallel to the y-z plane, said method comprising the steps of:
-
staging said workpiece such that said edge intersects said sensing plane, said edge intersecting said sensing plane at an intersection point having y and z coordinates; emitting electromagnetic energy such that said edge creates a shadow having a penumbra, said penumbra having an intensity-of-shadow which varies in the z dimension substantially according to a known function of said y and z coordinates; and calculating said y and z coordinates from the amount of energy which reaches respective first and second known detection regions in said penumbra. - View Dependent Claims (70, 71, 72, 73, 74, 75, 76, 77, 78, 79)
-
Specification