Apparatus for recording a wobbling, spiral guide groove on an optical disc

• US 4,942,565 A
• Filed: 07/28/1989
• Issued: 07/17/1990
• Est. Priority Date: 09/30/1986
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Lagadec, Roger
• Primary Examiner(s): Canney, Vincent P.
• Application Number:
  US07/387,425
• Time in Patent Office: 354 Days
• Field of Search: 360/20, 369/32, 369/44-47, 369/59, 369/93-95, 369/102, 369/108, 369/109, 369/111, 369/275, 369/277-279
• US Class Current: 369/47.49
• CPC Class Codes: C22B 11/08 by cyaniding
• CPC Class Codes: G11B 27/19 by using information detectable on the record carrier
• CPC Class Codes: G11B 27/3036 Time code signal
• CPC Class Codes: G11B 7/09 with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
• CPC Class Codes: G11B 7/24 Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the arrangement of information on the carrier G11B7/007
• CPC Class Codes: G11B 7/24085 Pits

Abstract

Recording apparatus for forming a track on a disk-shaped recording medium capable of optical information reproduction, comprises a deflection device for deviating a recording beam from a light source in a radial direction of the disk-shape recording medium and a deflection-control signal generating device. The deflection control signal is developed from the superimposition of a first signal having a predetermined frequency and a second signal having a lower frequency than the predetermined frequency. The superimposition of the second signal can be done while retaining the predetermined frequency.

Claims

1. Apparatus for forming a wobbling, substantially spiral pregroove on a disc-shaped recording medium for use as a tracking guide when subsequently recording data on the recording medium, said apparatus comprising:

means for rotating said disc-shaped recording medium;

a laser beam source for generating a laser beam;

means for moving said laser light beam source radially relative to said disc-shaped recording medium;

optical means for guiding said laser beam to said disc-shaped recording medium, said optical means including deflecting means for deflecting said laser beam in a radial direction of said disc-shaped recording medium in response to a modulated control signal while said disc-shaped recording medium rotates and said laser light beam source moves radially relative to said recording medium, whereby a wobbling, substantially spiral tracking guide pregroove is formed on said disc-shaped recording medium; and

control signal generating means connected to receive a first signal that has a first predetermined frequency and to receive a coded information second signal that has a second predetermined frequency at least an order of magnitude lower than said first predetermined frequency, said modulated control signal being generated by superimposing said second signal on said first signal, said modulated control signal being fed to said deflecting means for causing said laser light beam to wobble as the substantially spiral pregroove is formed on said recording medium in accordance with said modulated control signal.

2. Apparatus according to claim 1, wherein said second signal is an absolute time code signal having minutes information, seconds information and frames information in binary coded decimal form.

3. Apparatus according to claim 2, wherein said control signal generating means includes an absolute time code signal source for generating said absolute time code signal, means for receiving a clock signal with a frequency twice said first predetermined frequency, switching means receiving said clock signal at first and second inputs and producing an output by switching between said first and second inputs in accordance with said absolute time code signal, and filter means supplied with the output of said switching means and passing a frequency component including said first predetermined frequency, said filter means producing said modulated control signal as an output.

4. A method of forming a wobbling, substantially spiral pregroove on a disc-shaped recording medium for use as a guide when subsequently recording data on the recording medium, said method comprising the steps of:

rotating said disc-shaped recording medium;

radiating a laser beam;

guiding the laser beam to said disc-shaped recording medium and moving the laser beam radially on the rotating recording medium to form a substantially spiral pregroove, said guiding step including a step of deflecting the laser beam in a radial direction of said disc-shaped recording medium in response to a modulated control signal while said disc-shaped recording medium rotates and said laser light beam is moved radially on the rotating recording medium, whereby a wobbling, substantially spiral pregroove is formed on said disc-shaped recording medium;

generating said modulated signal by switching on and off a first signal that has a first predetermined frequency in accordance with a second signal that contains coded information and has a second predetermined frequency at least an order of magnitude lower than said first predetermined frequency; and

controlling said deflecting of said laser beam in accordance with said modulated control signal for wobbling said laser beam while forming said spiral pregroove on said recording medium.

5. A method according to claim 4, wherein said generating step includes steps of code-modulating said first signal by said second signal to produce a code-modulated signal and filtering the code-modulated signal to produce said control signal.

6. A disc-shaped recording medium capable of having a data signal optically recorded thereon and optically reproduced therefrom, said recording medium comprising:

a substrate layer having first and second surfaces, said first surface having formed thereon a substantially spiral pregroove which is wobbled in a radial direction of said disc-shaped recording medium and formed by a control signal consisting of a first signal that has a predetermined frequency and that has been modulated by a second signal that contains coded information and that has a frequency at least an order of magnitude lower than said predetermined frequency;

a recording layer formed on the first surface of said substrate layer and adapted for subsequent optically recording the data signal thereon; and

a protective layer formed on said recording layer.