EP0452793B1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Optical head having a hologram associated with the objective lens
Assignee: Panasonic Holdings Corp
•
Filing: 1991-04-10
•
Granted: 1998-01-28
•
Expires: 2011-04-10
Abstract
No abstract record available.
Inventors
- 👤 Makoto Kato
- 👤 Yoshiaki Raionzu Manshon Komma
- 👤 Shin-Ichi Kadowaki
- 👤 Yoshikazu Hori
- 👤 Seiji Nishino
- 👤 Tetsuo Saimi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-24 18:34
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/12; G11B7/13; G11B7/131; G02; G02B; G02B27/00; G02B27/0025; G02B27/0037; G02B27/42; G02B27/4233; G02B27/4238; G02B27/4272; G02B27/4277; G02B5/00; G02B5/18; G02B5/1814; G02B5/1819; G02B5/1847; G02B5/1857; G02B5/32; G11B7/08; G11B7/09; G11B7/094; G11B7/123; G11B7/135; G11B7/1353; G11B7/0908; G11B7/0912
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
435 words
A movable optical pick-up head apparatus of integrated
lens and hologram type, comprising: a light radiation source (1); an imaging optics means (3) having an optical axis
(7), for converging a light beam emitted from said light
radiation source (1) into a microspot on a data recording
medium (4); a hologram element (2) being incorporated integrally
with said imaging optic means (3) and including a diffraction
optical element on which two different kinds of blazed grating
or blazed linear Fresnel zone plate-like pattern are formed
alternately in a number, greater than or equal to four, of
regions (A,B) which are arranged in parallel with one another
so as to be successively adjacent to one another but which do
not overlap with one another, the hologram element (2)
producing a zero order diffraction component beam from a beam
emitted from said light radiation source (1), said imaging
optics means receiving said zero order diffraction component
beam so as to converge said zero order diffraction component
beam into a spot on a memory medium and further receiving a
reflected beam from the spot, said two different kinds of
pattern or grating producing a pair of first order diffraction
component beams having different focused points from said
reflected beam transmitted from said imaging optic means, said
first order diffraction component beams (15, 16) being focused
outside of said optical axis of said imaging optics means; a pair of optical detection means (12, 13) having beam
receiving surfaces which are located on a single plane (36)
which is disposed between said different focused points as
measured along said optical axis, said pair of first order
diffraction component beams impinging on respective ones of
said beam receiving surfaces of said pair of optical detection
means with spot sizes which are substantially equal to each
other if said imaging optics means focuses said zero order
diffraction component beam into said spot on said memory
medium, for differentially obtaining a focusing error signal
corresponding to a difference between said spot sizes of said
pair of first order diffraction component beams on said beam
receiving surfaces of said pair of optical detection means
when said imaging optics means does not focus said zero order
diffraction component beam into said spot on said memory
medium; and an actuator means (14) for driving said imaging optics
means (3) in accordance with said focusing error signal from
said optical detection means (12, 13) so as to allow said
imaging optics means to focus said zero order diffraction
component beam into said spot on said memory medium so that
said spot can scan precisely said memory medium.
Claim 2
Dependent Claim
32 words
The movable optical pick-up head apparatus as set
forth in claim 1, wherein said hologram element (2) is
composed of a stepped phase element which is quantized by more
than four levels.
Claim 3
Dependent Claim
30 words
The movable optical pick-up head apparatus as set
forth in claim 1 or 2, wherein another pair of blazed gratings
or Fresnel zone patterns is formed in other separate regions.
Claim 4
Dependent Claim
113 words
The movable pick-up head apparatus as set forth in any
preceding claim, wherein said light radiation source (1) is fixed to a small
size supporting and heat-radiating base; and a servo-signal and RF signal producing detector system
is provided including said pair of optical detection means
secured to said small size supporting and heat-radiating base,
near thereto and having a plurality of split zones receiving
said pair of wavefronts of diffraction components, for
differentially obtaining a focusing error signal and a
tracking error signal; said light radiation source, said
imaging optics, said hologram element and said servo-signal
and RF signal producing detector system being integrally
incorporated with each other in one unit body.
Claim 5
Dependent Claim
45 words
The movable optical pick-up head apparatus as set
forth in claim 4, wherein said one unit body is a closed
container-like body in which said light radiation source, said
imaging optics, said hologram element and said servo-signal
and RF signal producing detector system are disposed.
Claim 6
Dependent Claim
180 words
The movable optical pick-up head apparatus as set
forth in any preceding claim, wherein on said hologram element a plurality of pairs of
blazed Fresnel zone patterns are formed periodically and which
are not overlapped with each other so as to have such a
periodical structure that a plurality of wavefronts of
diffraction components having the same order but different
focuses are produced from a beam which is received from said
mircrospot on said memory medium by way of said imaging
optics, out of said optical axis of said imaging optics, and said pair of optical detection means includes a
focusing side detection means for detecting said wavefronts of
said diffraction components from said pairs of blazed Fresnel
zone patterns, for differentially obtaining a focusing error
signal; and a tracking side detection means for detecting said
wavefronts of said. diffraction components produced by said
periodical structure of the hologram element, for
differentially obtaining a tracking error signal, said imaging
optics and said hologram element being arranged near to each
other and integrally incorporated with each other in one unit
body.
Claim 7
Dependent Claim
38 words
The movable optical pick-up head apparatus as set
forth in claim 6, wherein said light radiating source, said
imaging optic, said hologram element and said optical
detection means are integrally incorporated with each other in
one unit body.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.