公开(公告)号：DE3577489D1

公开(公告)日：1990-06-07

申请号：DE3577489

申请日：1985-02-22

Applicant: IBM

Inventor： COLLINS DAVID WHINERY ,  JOHNSON JOEL SWENUM ,  SCHMIDT LAURENCE JOSEPH ,  SIVERLING MICHAEL MC HUGH ,  WENTINK WILLIAM STEWART

IPC: G11B21/02 ,  G01B11/00 ,  G11B5/455 ,  G11B5/48 ,  G11B5/56 ,  G11B33/10

Abstract: An optical tool (9) is disclosed which permits a sequence of aligned transducer gaps to be positioned parallel to the axis of a disk file. The tool is surfaced with transparent material (16, 17, 18), has a thickness the same as the disk or disks of a disk stack being simulated and presents an etched alignment grid (17) at the interface surface between transducer and tool. The virtually common plane of the transducer gap and etched grid substantially eliminates parallax and the unfilled etched grid permits the gap to be seen, whether aligned with the transparent unetched surface or the translucent etched surface portion. The use of inclined mirrored surfaces (16) underlying the grid permits alignment to be effected using a bright field microscope and observing from a direction rotated 90 degrees from a line perpendicular to the grid to enable alignment of transducer gaps confronting one another at opposite sides of the disk.

公开(公告)号：DE3069603D1

公开(公告)日：1984-12-13

申请号：DE3069603

申请日：1980-11-14

Applicant: IBM

Inventor： BURKE MICHAEL JOSEPH ,  COLLINS DAVID WHINERY

IPC: H02K29/00 ,  H02P6/12 ,  H02P6/02 ,  H02K29/02

Abstract: A brushless D. C. motor is disclosed having two bifilar winding wire pairs (P1, P3 and P2, P4) with each bifilar pair forming alternate windings. Each winding (P1 to P4) is switched by a transistor (T1-T4) which has a back poled diode (45) connected in parallel therewith. A control circuit sequences energization of single windings with each winding energized being in a different bifilar pair than the next preceding energized winding whereby when a transistor is switched off the other winding of the bifilar pair and the associated back poled diode protect the transistor and provide an energy conserving/heat eliminating path for the induced current. Each winding is further formed of a pair of subwindings having an angle of separation therebetween approximately half the angular separation between adjacent windings.