Optical recording and playback apparatus

Patent metadata

Field	Value
Publication number	US-9330705-B2
Application number	US-201514627353-A
Country	US
Kind code	B2
Filing date	Feb 20, 2015
Priority date	Mar 26, 2014
Publication date	May 3, 2016
Grant date	May 3, 2016

Abstract

An optical recording and playback apparatus includes: a light source configured to emit a light beam; a tracking mirror configured to change a direction of the light beam; a collimator configured to form the light beam into a parallel light beam; an objective lens configured to collect the parallel light beam to the optical tape; a lens actuator configured to adjust a position of the objective lens in a focus direction of the optical tape and a position of the objective lens in a tracking direction of the optical tape; a polarization hologram plate configured to separate a reflected light beam of the light beam; a photodetector receiving elements configured to receive the plurality of light fluxes; and a control circuit configured to control the lens actuator and the tracking mirror. The tracking mirror is disposed near the light source, and movable in the tracking direction.

First claim

What is claimed is:

1. An optical recording and playback apparatus comprising:
a light source configured to emit a light beam for forming a recording mark in an optical tape or a light beam for reading a state of the recording mark;
a tracking mirror configured to change a direction of the light beam emitted from the light source;
a collimator configured to form the light beam going through the tracking mirror into a parallel light beam;
an objective lens configured to collect the parallel light beam from the collimator to the optical tape;
a lens actuator configured to adjust a position of the objective lens in a focus direction of the optical tape and a position of the objective lens in a tracking direction of the optical tape;
a polarization hologram plate configured to separate a reflected light beam of the light beam with which the optical tape is irradiated through the objective lens into a plurality of light fluxes;
a photodetector having a plurality of light receiving elements configured to receive the plurality of light fluxes; and
a control circuit configured to control the lens actuator and the tracking mirror,
wherein
the tracking mirror is disposed near the light source, and movable in the tracking direction,
a numerical aperture of the objective lens ranges from 0.8 to 0.9 inclusive, and
the tracking mirror is movable within ±0.3 degrees in the tracking direction.

2. An optical recording and playback apparatus comprising:
a light source configured to emit a light beam for forming a recording mark in an optical tape or a light beam for reading a state of the recording mark;
a tracking mirror configured to change a direction of the light beam emitted from the light source;
a collimator configured to form the light beam going through the tracking mirror into a parallel light beam;
an objective lens configured to collect the parallel light beam from the collimator to the optical tape;
a lens actuator configured to adjust a position of the objective lens in a focus direction of the optical tape and a position of the objective lens in a tracking direction of the optical tape;
a polarization hologram plate configured to separate a reflected light beam of the light beam with which the optical tape is irradiated through the objective lens into a plurality of light fluxes;
a photodetector having a plurality of light receiving elements configured to receive the plurality of light fluxes; and
a control circuit configured to control the lens actuator and the tracking mirror,
wherein
the tracking mirror is disposed near the light source, and movable in the tracking direction, and
the tracking mirror is located within 6.5 mm from the light source.

3. The optical recording and playback apparatus according to claim 1 , wherein the tracking mirror is a micro electro mechanical systems (MEMS) mirror made of a silicon crystal, and has a size ranging from 1.3 mm to 2.4 mm inclusive and a thickness ranging from 10 um to 50 um inclusive.

4. The optical recording and playback apparatus according to claim 1 , further comprising a quarter-wave plate configured to circularly polarize a transmitted light beam,
wherein the objective lens, the polarization hologram plate, and the quarter-wave plate are integrally driven by the lens actuator, and positions of the objective lens, the polarization hologram plate, and the quarter-wave plate are adjusted in the tracking direction by an ECFF (Exchanged Correct Far Field) method.

5. The optical recording and playback apparatus according to claim 1 , wherein the tracking mirror is also movable in a track direction of the optical tape.

6. The optical recording and playback apparatus according to claim 5 , further comprising a calculator,
wherein the calculator is configured to generate a spot position signal indicating a position of a spot formed in the light receiving element of the photodetector, and
the control circuit is configured to control the tracking mirror using the spot position signal so as to correct the position of the spot.

Assignees

• Panasonic Ip Man Co Ltd

Inventors

• Saitoh Yohichi
• Hayashi Hideki
• Asada Jun-Ichi

Classifications

• G11B7/003 Primary

  with webs {, filaments or wires}, e.g. belts, spooled tapes or films of quasi-infinite extent · CPC title

• G11B7/0903

  Multi-beam tracking systems · CPC title

• G11B7/13

  Optical detectors therefor · CPC title

• G11B7/24009

  Tapes, long films or long sheets · CPC title

• G11B2007/0003

  Recording, reproducing or erasing systems characterised by the structure or type of the carrier · CPC title