Procedure and system for inspecting a component with leads to determine its fitness for assembly

• US 6,229,608 B1
• Filed: 06/10/1999
• Issued: 05/08/2001
• Est. Priority Date: 06/10/1999
• Status: Expired due to Fees

• Current Assignee: Pmj Automec Oyj
• Original Assignee: Pmj Automec Oyj
• Inventors: Morris, Joseph
• Primary Examiner(s): Pham, Hoa Q.
• Assistant Examiner(s): Nguyen, Sang H.
• Application Number:
  US09/329,542
• Time in Patent Office: 698 Days
• Field of Search: 356/375, 356/376, 356/400, 356/381, 356/372, 356/384, 356/385, 250/599.26
• US Class Current: 356/623
• CPC Class Codes: H05K 13/0813 Controlling of single components prior to mounting, e.g. orientation, component geometry H05K13/0812 takes precedence

Abstract

Procedure and system for inspecting a component (1) with leads to determine its fitness for assembly before the component is placed on a circuit board. A narrow illuminating beam (10) is directed from a light source (9) at a light-sensitive detector (11). The component (1) is moved in relation to the illuminating beam so that at least one of the leads (4) of the component passes through the illuminating beam and so that the position of the gripper (7) holding the component as a function of time is known. The position data of the gripper is registered. The signal produced by the light-sensitive detector as a result of the illuminating beam being intercepted and shadowed by the lead is registered. Based on the position data of the gripper and the signal produced by the light-sensitive detector position coordinates of a specified lead in relation to the gripper are determined in order to determine the position error, and, if a position error occurs, the position coordinates of said lead of the component are corrected to eliminate said error for making the insertion of the component possible.

Claims

1. A method for inspecting a component with leads to determine fitness of the component for assembly in conjunction with automatic circuit board assembly performed using an assembly robot before the component is placed on a circuit board, said component having leads to be inserted into corresponding holes in the circuit board, said robot being equipped with a gripper for taking hold of the component, the method comprising:

directing a narrow illuminating beam at a light-sensitive detector,

moving the component, oriented with a row of leads parallel to the illuminating beam, in relation to the illuminating beam so that at least one of the leads of the component passes through the illuminating beam and so that the position of the gripper holding the component as a function of time is known,

registering position data of the gripper,

registering a signal produced by the light-sensitive detector as a result of the illuminating beam being intercepted and shadowed by the leads, and

determining position coordinates of a specified lead in relation to the gripper based on the position data of the gripper and the signal produced by the light-sensitive detector in order to determine a position error, and, if a position error occurs, correcting the position coordinates of said lead of the component to eliminate said error for making insertion of the component possible.

2. A method as defined in claim 1, further comprising moving the component in relation to the illuminating beam so that all leads of the component pass through the illuminating beam,

computing, based on a pulse produced by the light-sensitive detector, at least one of a width of the lead row and a distance between adjacent leads rows,

comparing the at least one of the width of the lead row and the distance between adjacent leads rows with a specified allowed respective limit range,

placing the component on the circuit board when the at least one of the width and the distance between adjacent lead rows is within the allowed limit range, and

rejecting and removing the component without placing the component on the circuit board when the at least one of the width of the lead row and the distance between adjacent leads lies outside the allowed limit range.

3. A method as defined in claim 1, wherein the gripper holding the component is a gripper of an xyzw-robot.

4. A method as defined in claim 1, further comprising passing the component across the illuminating beam in a direction of one of the width and a length of the row of the leads.

5. A method as defined in claim 1, wherein the signal produced by the light-sensitive detector is a pulse, and the at least one of the width of the lead row and the distance between adjacent lead rows is computed on a basis of start and end instants of the pulse.

6. A method as defined in claim 1, further comprising the illuminating beam at the light-sensitive detector in a horizontal plane in an x-direction.

7. A method as defined in claim 1, wherein the assembly robot defines x, y and z directional axes, and further comprising setting the component to a position where the lead row lies in a horizontal plane in an x-direction before moving the component through the illuminating beam, and moving the component in a y-direction through the illuminating beam, the y-direction being orthogonal to the x-direction.

8. A method as defined in claim 1, wherein the assembly robot defines x, y and z directional axes, and further comprising setting the component to a position where the lead row lies in a horizontal plane in a y-direction before moving the component through the illuminating beam, and moving the component in an x-direction through the illuminating beam, the y direction being orthogonal to the x-direction.

9. A method as defined in claim 1, wherein the assembly robot defines x, y and z directional axes and further comprising moving the component is simultaneously in x and y directions through the illuminating beam.

10. A method as defined in claim 1, wherein the assembly robot defines x, y and z directional axes and further comprising adjusting the component in the z-direction, perpendicular to the x and y directions, before moving the component through the illuminating beam, to a position where plane of the illuminating beam intersects the leads adjacent to their free ends.

11. A method as defined in claim 1, further comprising rotating the component before moving the component through the illuminating beam.

12. A method as defined in claim 1, further comprising, before moving the component through the illuminating beam, rotating the component by a small amount about the z-axis so that the lead row rotates from a position parallel to the illuminating beam to define a small angle in relation to the direction of the illuminating beam;

determining the width of the lead row;

determining, based on the determined width of the lead row in relation to the predetermined lead row width, a rotation error of the component in relation to the gripper, and

correcting the position coordinates of said lead of the component correspondingly to eliminate the rotation error.

13. A method as defined in claim 1, further comprising inspecting the lead row of the component by moving the component through an illuminating beam oriented parallel to a direction of motion of a circuit board conveyor holding the circuit board, and

turning the component horizontally through 90°

and moving the component again through the illuminating beam.

14. A method as defined in claim 1, further comprising providing first and second parallel illuminating beams placed at a distance from each other and oriented parallel to a direction of motion of a circuit board conveyor holding the circuit board;

inspecting a first lead row of the component by passing the component through the first illuminating beam;

turning the component horizontally through 90°

; and

inspecting a second lead row of the component by passing the component through the second illuminating beam.

15. A method as defined in claim 1, further comprising providing two mutually perpendicular illuminating beams;

and

inspecting the lead row by moving the component through the two mutually perpendicular illuminating beams.

16. A method as defined in claim 1, further comprising generating the illuminating beam using a laser.

17. A system for inspecting a component with leads to determine fitness of the component for assembly in conjunction with automatic circuit board assembly performed using an assembly robot before the component is placed on a circuit board, said component having at least two leads to be inserted into corresponding holes in the circuit board, said robot being equipped with a gripper for taking hold of the component, the system comprising:

a first inspection device including a first light source to generate a first illuminating beam and a first light-sensitive detector at which the first illuminating beam is directed,

means for moving the component in relation to the illuminating beam so that at least one of the leads of the component pass through the illuminating beam and so that the position of the gripper holding the component as a function of time is known,

means for registering position data of the gripper,

means for registering the signal produced by the light-sensitive detector as a result of the illuminating beam being intercepted by the lead, and

means for determining, based on the position data of the gripper and the signal produced by the light-sensitive detector, position coordinates of a specified lead in relation to the gripper in order to determine a position error.

18. A system as defined in claim 17, wherein the robot is arranged to move the component across the first illuminating beam so that all leads of the component pass through the first illuminating beam;

and

the system further comprises

means for computing at least one of a lead row width and a distance between adjacent lead rows, and

means for comparing the at least one of the lead row width and the distance between adjacent lead rows with a specified allowed limit value.

19. A system as defined in claim 17, wherein the robot is disposed to move the component in at least one of a direction parallel to and perpendicular to the lead row.

20. A system as defined in claim 17, wherein the first light source is disposed so that the first illuminating beam is horizontal.

21. A system as defined in claim 17, is a xyzw-robot.

22. A system as defined in claim 17, wherein the first light source is disposed so that the first illuminating beam is parallel to an x-axis lying parallel to a direction of motion of a conveyor holding the circuit board, the circuit board lies in an xy-plane defined by the x-axis and a horizontal y-axis orthogonal to the x-axis.

23. A system as defined in claim 17, further comprising a second inspection device producing a second illumination beam parallel to the first illuminating beam and spaced apart from the first illuminating beam.

24. A system as defined in claim 17, further comprising a second inspection device producing a second illuminating beam perpendicular to the first illuminating beam.

25. A system as defined in claim 17, wherein the first inspection device is disposed between a component feed device and a circuit board conveyor holding the circuit board.

27. A system as defined in claim 17, wherein the first light source is a laser.

28. A system as defined in claim 17, wherein a width of the first illuminating beam is no more than a lead thickness.

29. A system as defined in claim 17, wherein a width of the first illuminating beam is of around 0.1 mm.

26. A system as defined in claim 26, wherein the first inspection device is disposed on a component transfer route between the component feed station and the circuit board, so that inspection of the leads is performed as the robot transfers the component between the component feed station and the circuit board, substantially without stopping and substantially without diverging from the component transfer route between the component feed station and the circuit board.

30. A system for inspecting a component with leads to determine fitness of the component for assembly in conjunction with automatic circuit board assembly performed using an assembly robot before the component is placed on a circuit board, said component having at least two leads to be inserted into corresponding holes in the circuit board, the system comprising:

a first inspection device including a first photodetector and first light source generating a first illuminating beam directed at the first photodetector;

a gripper arranged to hold the component with a row of component leads being parallel the illuminating beam and to move the component relative to the first illuminating beam so that at least one of the component leads passes through the illuminating beam;

a controller coupled to the gripper to track a gripper position as a function of time, and coupled to receive a detection signal from the first photodetector, and to determine a position of the at least one of the component leads.

31. A system as defined in claim 30, wherein the photodetector detects an optical signal related to at least one of a width of a component lead row and a separation distance between adjacent component lead rows, and the controller determines the least one of a width of a component lead row and a separation distance between adjacent component lead rows from the detection signal received from the photodetector.