육안 검사 자동화 기술

제 Ⅰ 단원 육안 검사 자동화를 위한 요소 기술
제 1장 육안 검사 자동화의 개요 ·································································· 13
1.1 측정과 검사의 구별 ······················································································· 15
1.1.1 측정의 문제 ···························································································· 15
1.1.2 계측과 측정의 차이 ·············································································· 16
1.1.3 측정과 검사의 차이 ·············································································· 17
1.2 비파괴 검사의 개요 ······················································································ 18
1.2.1 비파괴 검사의 정의 ·············································································· 18
1.2.2 비파괴 검사의 원리 ············································································· 18
1.2.3 비파괴 검사의 종류와 특징 ································································ 18
1.3 검사의 목적과 동향 ······················································································ 22
1.3.1 검사의 목적 ··························································································· 22
1.3.2 검사의 동향 ·························································································· 24
1.4 육안 검사 시스템의 사례 ············································································ 25
1.4.1 전기전자 산업에의 응용 ······································································ 25
1.4.2 자동 제조 산업에의 응용 ···································································· 27
1.4.3 고밀도 실장 회로판 제조 공정에의 응용 ········································· 29
1.4.4 비전 검사 ······························································································ 35
1.5 검사의 문제점 ······························································································· 37
1.5.1 검사 기술의 문제점 ············································································· 37
1.5.2 검사의 자동화를 위한 문제점 ···························································· 38
1.6 육안 검사와 자동화 ······················································································ 39
1.6.1 서론 ········································································································ 39
1.6.2 자동화의 순서 ······················································································· 41
제 2장 광학 기술의 개요 ·············································································· 45
2.1 광학의 개요 ··································································································· 47
2.1.1 광의 편광 ······························································································· 47
2.1.2 굴절과 반사 ·························································································· 50
2.1.3 빛의 산란 ······························································································ 56
2.1.4 빛의 회절 ······························································································ 57
2.2 광원의 개요 ··································································································· 62
2.2.1 백색 광원 ······························································································ 62
2.2.2 레이저 다이오드 ·················································································· 62
2.2.3 발광 다이오드 ····················································································· 80
2.3 광센서의 개요 ······························································································· 85
2.3.1 광전 현상 ······························································································ 85
2.3.2 광전 소자의 특성표시법 ····································································· 93
2.3.3 광센서 ··································································································· 95
2.4 조도 ·············································································································· 113
2.5 조명계 ··········································································································· 115
제 3장 신호처리와 변환 기술의 개요 ························································ 117
3.1 전기회로 소자 ······························································································ 119
3.1.1 저항기 ··································································································· 119
3.1.2 콘덴서 ·································································································· 122
3.1.3 인덕터 ·································································································· 125
3.2 전자회로 소자 ····························································································· 130
3.2.1 진성반도체의 성질 ·············································································· 131
3.2.2 n형 반도체와 p형 반도체 ································································ 132
3.2.3 다이오드 ······························································································ 133
3.2.4 트랜지스터 ·························································································· 136
3.3 전기전자 회로의 개요 ················································································ 144
3.3.1 다이오드 회로 ····················································································· 144
3.3.2 트랜지스터 회로 ················································································ 154
3.3.3 연산 증폭 회로 ·················································································· 163
3.4 신호 변환의 개요 ······················································································· 167
3.4.1 기본적인 입력 회로 ··········································································· 167
3.4.2 매칭 회로 ··························································································· 180
3.4.3 신호의 증폭 ························································································ 184
3.4.4 파형 변환 ···························································································· 187
3.4.5 논리 회로 ··························································································· 200
3.4.6 연산 회로 ··························································································· 209
3.4.7 샘플링과 양자화 ················································································ 220

제 Ⅱ 단원 육안 검사 자동화의 실용 기술
제 4장 외관 결함의 센싱 ············································································ 229
4.1 외관 결함과 광학 정보 관계 ····································································· 231
4.2 표면 오염 ···································································································· 232
4.3 표면흠집, 표면 거칠함, 먼지 부착 ························································· 234
4.4 요철 ············································································································· 238
4.5 윤곽 ·············································································································· 241
4.6 투명체 ·········································································································· 244
4.7 용기의 누설 ································································································ 246
4.8 둘레 전체의 검사 ······················································································· 247
제 5장 광센서의 이용법 ·············································································· 249
5.1 점 센서의 이용법 ························································································ 251
5.1.1 일반사항 ······························································································· 251
5.1.2 광전자증배관 ······················································································ 254
5.1.3 포토다이오드 ······················································································ 256
5.2 라인 센서의 이용법 ··················································································· 258
5.3 면 센서의 이용법 ······················································································· 261
5.4 플라잉스폿 시스템 ····················································································· 264
5.5 플라잉이미지 시스템 ················································································· 267
5.6 밀착형 이미지센서 ····················································································· 268
5.7 결상 광학계 ································································································ 269
5.8 화상의 떨림 방지 ······················································································· 271
제 6장 검사의 알고리즘 ·············································································· 275
6.1 비교기준 데이터의 표현법 ········································································ 277
6.1.1 피측정물 내부에서의 비교 ································································ 277
6.1.2 창성된 정상 패턴과의 비교 ····························································· 280
6.1.3 형상 특성치와의 비교 ······································································· 283
6.1.4 결함 국소 패턴의 유무 판정 ··························································· 286
6.1.5 실물과의 비교 ···················································································· 288
6.1.6 설계 데이터와의 비교 ······································································ 290
6.1.7 메모리상의 화상 데이터와의 비교 ··················································· 291
6.2 화상 데이터의 절감법 ··············································································· 292
6.2.1 정점 샘플링 ······················································································ 292
6.2.2 라인 ····································································································· 293
6.2.3 윈도우 ································································································· 295
6.2.4 마스킹(masking) ··············································································· 296
6.2.5 화상 데이터의 차원 압축 ································································ 296
6.3 비교 연산 ···································································································· 299
6.4 위치의 보정 ································································································ 301
6.5 판정 기준 데이터의 설정법 ····································································· 303
제 7장 신호 레벨 해석에 의한 결함 검출 ··············································· 305
7.1 개요 ·············································································································· 307
7.2 신호의 보정 ································································································ 308
7.3 결함부의 강조 ······························································································ 311
7.4 임계값 회로 ································································································· 312
7.5 검사 영역의 절단 ······················································································· 314
제 8장 2차원 화상 처리에 의한 결함 검출 ·············································· 319
8.1 개요 ·············································································································· 321
8.2 2치화와 화소의 분리 ················································································· 323
8.3 파이프라인 처리 회로 ··············································································· 325
8.4 국소 병렬 연산의 응용 예 ······································································· 329
8.5 PC의 이용 ··································································································· 332
제 9장 검사 장치의 구성 ············································································ 333
9.1 점 센서에 의한 형상 검사 장치 ······························································ 335
9.2 라인 센서에 의한 표면 결함 검사 장치 ················································· 338
9.3 영상 카메라를 이용한 윈도우 회로 ························································· 341
제 10장 성능의 검토 ··················································································· 343
10.1 개요 ············································································································ 345
10.2 정도 ············································································································ 345
10.3 분해능 ········································································································ 347
10.3.1 샘플링 정리 ······················································································ 347
10.3.2 촬상소자와 분해능 ·········································································· 349
10.3.3 Laser 주사와 분해능 ····································································· 350
10.3.4 렌즈의 해상력 ·················································································· 352
10.3.5 증폭회로와 분해능 ·········································································· 352
10.3.6 위치결정 정도의 영향 ···································································· 353
10.3.7 분해능의 향상 ·················································································· 354
10.4 검사 속도 ·································································································· 355
10.5 재현성 ········································································································ 356
10.6 그 밖의 평가 ····························································································· 357

[ 저자서문 ]

4차 산업 시대를 맞이하여 생산 제조 현장에서는 생산 자동화를 피해 갈 수 없게 되었다. 따라서 제품의 품질 또는 공정상의 불량품 검사가 더욱 중요하게 되었다. 제품의 품질이 떨어지거나 공정상의 불량품으로 회사(기업)에 악영향을 미치는 사례를 종종 뉴스 등으로 접한다. 그러나 아직까지 불량품 검사 등이 사람의 육안에 의존하는 경우가 상당히 많다. 물론 육안 검사를 자동화 하는데 한계 및 문제점들을 갖고 있지만 이러한 문제점 및 한계점을 극복하지 않으면 경쟁 시대에 견딜 수 없다.
육안 검사의 자동화는 불량품 출하에 동반하는 경제적 손실을 방지할 수 있을 뿐만 아니라 검사 결과를 가공 공정에 피드백 함으로써 제조 공정 전체의 품질 안정화가 가능하게 된다. 또한 납입 검사에 적용함에 따라 거래에 있어서의 검사 기준이 객관화될 수 있으므로 공정 간 또는 기업 간에 있어서 주고받음을 안정화할 수 있다.
이러한 자동 육안 검사 장치는 공학기술, 전기-전자기술, 기계기술의 3가지와 소프트 기술이 밀접하게 연관되어 구성되어 있다. 여기서는 결함을 검출하는 센싱 기술, 검사를 위한 데이터 처리 알고리즘, 실용적인 신호처리 하드웨어 등에 중점을 두고 꾸며 보았다.
이 책의 구성은 크게 2파트로 꾸며져 육안 검사 자동화를 위한 요소 기술과 육안 검사 자동화의 실용 기술로 이루어졌다. 첫 번째 파트는 육안 검사 자동화를 위한 기초적인 요소 기술로서 육안 검사의 이해를 돕기 위한 자동화 순서를 포함한 전반적인 내용과 육안 검사에서 필수적인 광학 기술의 기본 이해 및 신호 처리와 변환 기술의 기초적인 요소를 이해하는데 목표를 두고 구성하였다. 두 번째 파트는 실제로 육안 검사를 자동화한다고 가정하고 어떤 외관 결함이 있으며 어떤 방법으로 센싱할 것이며 검사는 어떻게 할 것인지에 대해 서술했으며 마지막으로 실제로 육안 검사 자동화 시스템을 구성해 보고 성능도 검토하는 내용으로 구성하였다.

사람은 육안으로 두 패턴(형체)간의 차이점을 발견하는데 탁월한 능력을 지니고 있으며 대상 물체가 가지고 있는 여러 요소를 조합해서 종합적인 판단을 내릴 수 있는 능력도 있다.
그러나 육안 검사는 아래와 같은 문제점이 있다.
① 판정 결과의 편차가 크다.
∼ 개인차, 혹은 동일인이라 하더라도 시간의 경과나 그 날의 기분에 따라 검사 기준이 변할 수 있다. 또 불량률이 높아질 때는 기준을 느슨하게 불량률이 낮을 때는 기준을 필요 이상으로 높게 설정하는 경향이 있다.
② 육안으로 식별이 가능한 최소 치수는 0.11㎜이다.
③ 불량을 판정하는데 0.2∼0.4초가 소요된다.