Apparatus for automatically inspecting electrical connecting pins

• US 4,696,047 A
• Filed: 02/28/1985
• Issued: 09/22/1987
• Est. Priority Date: 02/28/1985
• Status: Expired due to Fees

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Christian, Donald J., Stachowicz, Michael J.
• Primary Examiner(s): Boudreau, Leo H.
• Assistant Examiner(s): Couso, Jose L.
• Application Number:
  US06/707,116
• Time in Patent Office: 936 Days
• Field of Search: 382/8, 356/394, 356/398, 356/379, 356/380, 356/383, 358/106, 358/107
• US Class Current: 382/146
• CPC Class Codes: G01N 21/95 characterised by the material or shape of the object to be examined G01N21/89 - G01N21/91, G01N21/94 take precedence
• CPC Class Codes: G01N 21/956 Inspecting patterns on the surface of objects contactless testing of electronic circuits G01R31/308; testing currency G07D; manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: G01R 31/66 Testing of connections, e.g. of plugs or non-disconnectable joints testing for incorrect line connections G01R31/55

Abstract

An automatic pin inspection apparatus and method inspects a plurality of pins that are arranged in a predetermined configuration such as parallel rows and converts the image of the pins to a digital signal for application to a computer system. The digital system is compared with a known reference stored in a memory within the digital computer system and units that do not meet specified tolerances are rejected. A conveyer mechanism ensures the automation of the process. A centering technique is implemented and compensates for the jittering due to the movement of pins to ensure proper alignment of the image prior to the comparison being made.

Claims

1. A pin inspection system for inspecting a plurality of pins tips arranged in a predetermined configuration comprising:

illuminating means for illuminating the tips only, of pins which are of correct length, and which do not illuminate the tips of pins which are too long or too short;

video camera means for obtaining a video image of the illuminated pin tips by sweeping in a raster scan fashion the pin tips to obtain a first waveform representing light intensity versus relationship to the raster scan position;

a comparator for comparing the first waveform to a predetermined threshold and to provide a first logic state when the amplitude of the waveform is about the predetermined threshold and a second logic state when the amplitude of the first waveform is below the predetermined threshold;

memory means for arranging the first and second logic states according to the raster scan position;

summation means for locating clusters of the first logic states in both the row and column directions of the memory means;

isolation means for isolating clusters in the first logic state;

inertia measuring means for locating the first moment of inertia for each of the isolated clusters of the first logic state to obtain a first coordinate for each cluster;

transformation means for transforming the first coordinates to physical distances;

comparator means for comparing the physical distance to a predetermined criterion; and

classifying according to the results of the comparison the transform coordinates to obtain the results of the pin tips inspection.

2. The pins inspection system according to claim 1 wherein the illuminating means comprises:

means for providing a source of light;

means for transporting the light from the source of light means to the pin tip; and

means for focusing the light on the plurality of pin tips.

3. The pin inspection system according to claim 2 wherein the transport means comprises:

a bifurcated bundle of optical fibers.

4. The pin inspection system according to claim 1 wherein the plurality of pins are arranged in rows and columns and the video camera means comprises:

means for performing row projections on the image of the plurality of pin tips; and

means for performing column projections on the image of the plurality of pin tips.

5. A method of inspecting a plurality of pin tips arranged in a predetermined configuration for presence, straightness and contamination comprises:

illuminating the tips only, of pins which are of correct length, and not illuminating the tips of pins which are too long or too short;

attaining a video image of the illuminated pin tips by sweeping in a raster scan fashion the pin tips to obtain a first waveform representing light intensity in relationship to the raster scan position;

comparing the waveform to a predetermined threshold and to provide a first logic state when the amplitude of the first waveform is above the threshold and to provide a second logic state when the amplitude of the waveform is below the predetermined threshold;

arranging the first and second logic states according to raster scan position;

locating clusters of the first logic states in both the first and second direction;

isolating the clusters of the first logic states;

finding the first moment f inertia of the isolated clusters of the first logic state in a first and second direction to obtain a first coordinates for each cluster;

transforming the coordinates to physical distances;

comparing the physical distance to a predetermined criteria; and

classifying the results of the comparison to obtain the results of the pin inspection method.

6. The method according to claim 5 wherein the steps of illuminating the pins tips further comprises the steps of:

providing a source of light;

transporting the light from the light source to the pin tips; and

focusing the light on the plurality of pin tips.