公开(公告)号：EP0860946A3

公开(公告)日：2000-01-26

申请号：EP97120503.4

申请日：1997-11-21

申请人： Harness System Technologies Research, Ltd. ,  Sumitomo Wiring Systems, Ltd. ,  SUMITOMO ELECTRIC INDUSTRIES, LTD.

发明人： Mizuno, Fumiaki, c/o Harness Syst.Techn. Res., Ltd ,  Hoshino, Takashi c/o Harness Syst.Techn. Res., Ltd ,  Kido, Motonori, c/o Harness Syst.Techn. Res., Ltd ,  Miyazaki, Yoshiyuki, Harness Syst.Techn. Res., Ltd

IPC分类号： H03K17/082

CPC分类号： H03K17/18 ,  H02H1/043 ,  H02H3/085 ,  H02H3/087 ,  H02H3/0935 ,  H03K17/0822

摘要： A microcomputer 4 responds to an instruction signal to turn the lamp L on or off to control the FET 2 to be turned on or off through the drive circuit 5. The microcomputer 4 samples an electric current I L which is supplied through the A/D converter 6 and which flows in the lamp L at every predetermined sampling time T S and subjects the sampled electric current I L to a comparison with a known rated current value I R for the lamp L. When I L ≥ I R is satisfied, the microcomputer 4 starts counting energizing time T. When the accumulated value of I L × T S is enlarged to a predetermined value S O , the microcomputer 4 turns the FET 2 off. When the detected electric current I L is larger than an upper limit I O (> I R ) determined previously, the microcomputer 4 immediately turns the FET 2 off through the drive circuit 5.