Title:
OPTICAL HEAD DEVICE
Document Type and Number:
Japanese Patent JP3662751
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To provide an optical head device where the ratio of the quantity of light used for detecting an information signal being recorded on a disk and a track error signal according to the phase difference method to the quantity of light of reflection light from the disk is large and a high S/N ratio can be obtained for the signals.
SOLUTION: Reflection light from a disk 6 is diffracted by a hologram optical element 7 and is received by a photodetector 9. A focus error signal is detected from the -1 order diffraction light of the hologram optical element 7, and a track error signal by the phase difference method from the +1 order diffraction light of the hologram optical element 7, a track error signal by the push- pull method, and an information signal being recorded on the disk 6 are detected. The diffraction efficiency of the +1 order diffraction light is higher than that of the -1 order diffraction light.
Inventors:
Ryuichi Katayama
Application Number:
JP32865698A
Publication Date:
June 22, 2005
Filing Date:
November 18, 1998
Export Citation:
Assignee:
NEC
International Classes:
G11B7/09; G11B7/13; G11B7/135; G11B7/12; (IPC1-7): G11B7/135; G11B7/09; G11B7/13
Domestic Patent References:
| JP6236564A | ||||
| JP60157737A | ||||
| JP61248240A | ||||
| JP4355221A | ||||
| JP11238234A | ||||
| JP6290481A | ||||
| JP6290504A |
Attorney, Agent or Firm:
Masahiko Desk
Masashi Kudo
Yasuhisa Tanizawa
Masashi Kudo
Yasuhisa Tanizawa
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