公开(公告)号：DE3676979D1

公开(公告)日：1991-02-21

申请号：DE3676979

申请日：1986-11-11

Applicant: IBM

Inventor： ASADA SHIGEKI ,  HASEGAWA MEGUMI

IPC: H04N1/19 ,  H04N1/047 ,  H04N1/10 ,  H04N1/193 ,  H04N1/403 ,  H04N1/028

Abstract: A reference position marker (9) on a document support table (3) is positioned within the field of view of a CCD sensor array (8) which senses an image of a document (10) placed on the table. … To distinguish the reference position marker (9) from the document image, the marker has a high reflectance surface and a round cross section to directly reflect light from a lamp (4) into the CCD sensor array (8) to cause the array to operate in a saturated range to generate a higher output signal than the highest signal expected during the document scanning operation. A control unit (30) sets a threshold of a comparator circuit (33) to a level which is exceeded by the higher output signal in the marker recognition operation and not exceeded by the highest signal generated during the document scanning operation. The threshold level is switched by the control unit after the marker (9) is detected to a level for producing bi-level signals representing the image of the document.

公开(公告)号：JPS62159972A

公开(公告)日：1987-07-15

申请号：JP29340485

申请日：1985-12-27

Applicant: IBM

Inventor： ASADA SHIGEKI ,  HASEGAWA MEGUMI

IPC: H04N1/19 ,  H04N1/047 ,  H04N1/10 ,  H04N1/193 ,  H04N1/403