Disc player and focus search control method

• US 6,545,956 B2
• Filed: 03/20/2001
• Issued: 04/08/2003
• Est. Priority Date: 03/31/2000
• Status: Expired due to Fees

• Current Assignee: Pioneer Corporation
• Original Assignee: Pioneer Corporation
• Inventors: Hashizuka, Yoshihiro, Shimamura, Takao
• Primary Examiner(s): Edun, Muhammad
• Application Number:
  US09/811,624
• Publication Number:
  US 20010026506A1
• Time in Patent Office: 749 Days
• Field of Search: 369/44.23, 369/44.25, 369/44.26, 369/44.27, 369/44.34, 369/47.1, 369/53.1, 369/53.23, 369/53.45, 369/93, 369/94
• US Class Current: 369/44.27
• CPC Class Codes: G11B 2007/0006 adapted for scanning different types of carrier, e.g. CD & DVD
• CPC Class Codes: G11B 7/08511 with focus pull-in only

Abstract

A disc player can be used in common for discs having different focus positions of an object lens with respect to a recording surface. The disc player carries out focus servo control with respect to the discs and reads out recorded information. The disc player comprises a judging device, a waveform setting device and a focus searching device. The judging device judges a type of disc set at the disc player. The waveform setting device selectively sets a predetermined waveform information in accordance with results of judgement by the judging device, from a plurality of waveform information which are held in advance for use in focus searching for the types of discs. The focus searching device generates a focus search signal based on the waveform information set by the waveform setting device, and carries out focus searching, at a time of start-up of the disc player, before the focus servo control is carried out.

Claims

1. A disc player which can be used in common for a plurality of types of discs having different focus positions of an object lens with respect to a recording surface, and which carries out focus servo control with respect to the discs and reads out recorded information, the disc player comprising:

a judging device which judges a type of disc set at the disc player;

a waveform setting device which, from a plurality of waveform information which are held in advance for use in focus searching for the plurality of types of discs, selectively sets a predetermined waveform information in accordance with results of judgement by the judging device; and

a focus searching device which, at a time of start-up of the disc player, before the focus servo control is carried out, generates a focus search signal based on the waveform information set by the waveform setting device, and carries out focus searching.

2. The disc player according to claim 1, wherein the waveform information is information for generating triangular, wave-shaped focus search signals, each of which has a predetermined peak value and a predetermined bottom value.

3. The disc player according to claim 1, wherein the waveform information is information for generating triangular, wave-shaped focus search signals, for each of which a predetermined initial polarity is set.

4. The disc player according to claim 1, wherein the plurality of waveform information include waveform information set at a time when the type of the disc cannot be judged by the judging device, and the waveform information has a variation range which corresponds to all of the plurality of types of discs.

5. A focus search control method in a disc player which can be used in common for a plurality of types of discs having different focus positions of an object lens with respect to a recording surface, and which carries out focus servo control with respect to the discs and reads out recorded information, the focus search control method comprising the processes of:

judging a type of disc set at the disc player;

selectively setting a predetermined waveform information in accordance with results of the judging, from a plurality of waveform information which are held in advance for use in focus searching for the plurality of types of discs; and

generating a focus search signal based on the set waveform information and carrying out focus searching, at a time of start-up of the disc player, before the focus servo control is carried out.

6. The focus search control method according to claim 5, wherein the waveform information is information for generating triangular, wave-shaped focus search signals, each of which has a predetermined peak value and a predetermined bottom value.

7. The focus search control method according to claim 5, wherein the waveform information is information for generating triangular, wave-shaped focus search signals, for each of which a predetermined initial polarity is set.

8. The focus search control method according to claim 5, wherein the plurality of waveform information include waveform information set at a time when the type of the disc cannot be judged in the judging process, and the waveform information has a variation range which corresponds to all of the plurality of types of discs.