Shape testing apparatus

• US 4,343,553 A
• Filed: 08/27/1980
• Issued: 08/10/1982
• Est. Priority Date: 09/03/1979
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Oshida, Yoshitada, Akiyama, Nobuyuki, Makihira, Hiroshi, Nakagawa, Yasuo
• Primary Examiner(s): Rosenberger, R. A.
• Application Number:
  US06/181,768
• Time in Patent Office: 713 Days
• Field of Search: 356/376, 356/394, 250/202, 250/560, 358/96, 358/101
• US Class Current: 356/606
• CPC Class Codes: G01B 11/00 Measuring arrangements characterised by the use of optical techniques
• CPC Class Codes: G01B 11/2545 with one projection direction and several detection directions, e.g. stereo

Abstract

A shape detecting apparatus comprises a slit projecting means for projecting a slit image on a three-dimensional object such as a soldered area, a positioning means for positioning the three-dimensional object relative to the slit projecting means, an image pickup means for two-dimensionally scanning the slit image projected by the slit projecting means to pickup the image, a light segment extracting circuit including a center position extracting means for extracting a mean position (Z₁ +Z₂)/2 of two position signals Z₁ and Z₂ at which a video signal derived by transversely scanning the slit image by the image pickup means corresponds, to a first higher reference V₁ when the video signal exceeds the first higher reference V₁, a maximum value position extracting circuit for extracting a position Z corresponding to a maximum value of the video signal when the maximum value of the video signal is no higher than the first higher reference V₁ and exceeds a second lower reference V₂ and an erasing means for erasing the position signal when the maximum value of the video signal is no higher than the second lower reference V₂, and a detecting means for detecting undersoldered condition and oversoldered condition by analyzing and evaluating the three-dimensional object based on the light segment position information derived from the light segment extracting circuit.

Claims

1. A shape detecting apparatus comprising:

(a) a slit projecting means for projecting a slit image on a three-dimensional object;

(b) a positioning means for positioning said three-dimensional object relative to said slit projecting means;

(c) an image pickup means for two-dimensionally scanning the slit image projected by said slit projecting means to pickup the image;

(d) a light segment extracting circuit including

a center position extracting means for extracting a mean position (Z₁ +Z₂)/2 of two position signals Z₁ and Z₂ at which a video signal derived by transversely scanning said slit image by said image pickup means corresponds to or approximates to a first higher reference V₁ when a maximum value of said video signal exceeds said first higher reference V₁,

a maximum value position extracting means for extracting a position Z corresponding to the maximum value of said video signal when the maximum value of said video signal is no higher than said first higher reference V₁ and exceeds a second lower reference V₂, and

an erasing means for erasing the position signal of said video signal when the maximum value of said video signal is no higher than said second lower reference V₂ ; and

(e) a detecting means for detecting a shape of said three-dimensional object by analyzing the light segment position information derived from said light segment extracting circuit.

2. A shape detecting apparatus according to claim 1 further comprising a waveform preprocessing means for comparing said light segment position Z_i and adjacent light segment positions Z_i-1 and Z_i+1 on both sides thereof to select the least changing value as a light segment position Z_i '"'"' in order to erase noises and interpolating with one of said adjacent light segment positions Z_i-1 '"'"' and Z_i+1 '"'"' when said light segment position Z_i '"'"' is zero.

3. A shape detecting apparatus according to claim 2 wherein said slit projecting means is arranged to project the slit image perpendicularly to said three-dimensional object and said image pickup means includes a first image pickup means and a second image pickup means arranged to pickup the image obliquely on both sides of the center of said three-dimensional object.

4. A shape detecting apparatus according to claim 3 wherein said light segment extracting circuit includes two means to correspond to said first and second image pickup means, respectively.

5. A shape detecting circuit according to claim 4 further comprising an adder means for inverting the position signal derived from one of said light segment extracting means and combining the inverted position signal with the position signal derived from the other light segment extracting means.

6. A shape detecting apparatus according to claim 1 wherein said object is a soldered area and said detecting means defines a plurality of detection areas and determines areas of the respective detection areas to determine undersoldering and oversoldering.