公开(公告)号：CA2012800C

公开(公告)日：1995-01-17

申请号：CA2012800

申请日：1990-03-22

Applicant: IBM

Inventor： CHOW WILLIAM W ,  FENNEMA ALAN A ,  FIORINO BENJAMIN C ,  HENDERSON IAN E ,  KADLEC RONALD J ,  ROBERTS SPENCER D

IPC: G05D3/12 ,  G11B7/085 ,  G11B11/105 ,  G11B21/08 ,  G11B7/00

Abstract: A track-seeking apparatus of a disk recorder employs a track-crossing sensor to produce track-crossing signals. An oscillator is slaved to the sensor for supplying substitute track-crossing pulses in the absence of the sensor providing such pulses or when the radial velocity exceeds a threshold velocity. A velocity profile means alters the oscillator frequency so that the oscillator produces track-crossing pulses in accordance with the profile. TU988001

公开(公告)号：DE68906047T2

公开(公告)日：1993-10-28

申请号：DE68906047

申请日：1989-02-07

Applicant: IBM

Inventor： DIMATTEO JOSEPH HOWARD ,  FIORINO BENJAMIN C ,  FENNEMA ALAN AUGUST ,  LEWKOWICZ JULIAN

IPC: G11B7/085 ,  G11B7/09 ,  G11B7/095 ,  G11B7/08

Abstract: A focus acquire circuit for use in optical systems, such as optical data recorders and players, uses up to three parameter signals to indicate an in-focus condition. The zero crossing of a focus error signal is combined with a signal indicating that the focus error signal has approached a peak value and with a signal indicating a change in laser drive signal amplitude to indicate an in-focus condition. Various circuit details are illustrated showing how the three parameters can be combined together for indicating an in-focus condition.

公开(公告)号：CA978263A

公开(公告)日：1975-11-18

申请号：CA188787

申请日：1973-12-21

Applicant: IBM

Inventor： FIORINO BENJAMIN C

IPC: G11B15/087 ,  G11B20/12 ,  H03K5/153 ,  H04L1/00 ,  H04L7/10 ,  H04L25/04

Abstract: The base frequency of digital data signal is detected by using the transitions in the digital signal to control the duration of ramp signals generated by ramp generators. One ramp is restarted by each positive transition while a second ramp is restarted by each negative transition. Comparators monitor each ramp and compare the ramp against a threshold level. The threshold is set so that the comparator will change its state of output at a time period T=1/2f where f is the base frequency of the expected data signal. The outputs from the two comparators are exclusive-OR'd to produce a signal whose duration is a measure of the frequency departure of the input data signal from the expected data frequency. The output of the exclusive-OR is integrated to obtain an average DC voltage level which is a measure of the frequency of the input data signal. This average DC level varies linearly with the departure of the input data frequency from the expected data frequency. The output of the integrator is compared against a threshold by a comparator. This comparator generates an output signal indicating when the frequency of the input data signal is approaching the expected data frequency, i.e., the condition of beginning of record or beginning of data block. The threshold used by this last comparator may be adjusted to change the selectivity or bandwidth of frequencies that will result in the apparatus detecting the beginning of a data record.

公开(公告)号：CA906623A

公开(公告)日：1972-08-01

申请号：CA906623D

Applicant: IBM

Inventor： FIORINO BENJAMIN C ,  RODRIGUEZ JUAN A

IPC: G01P3/58 ,  G11B15/46 ,  H03G3/34 ,  H03K5/13