EP0357323A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Optical pickup device
Assignee: Sharp Corp
•
Filing: 1989-08-23
•
Granted: —
•
Expires: 2009-08-23
Abstract
Abstract An optical pickup device for focusing an irradiating ray from a light emitting element (1) on a recording medium (5) and letting a reflected ray reflected from this recording medium focus on a light receiving element (6) is characterized in comprising a diffracting element (2) disposed before the light emitting element and the light receiving element, at least a first diffraction region (2a) included in the diffracting element for separating the irradiating ray from the light emitting element into a main beam and sub-beams shifted from the main beam in a direction perpendicular to a track direction of the track where the main beam is focused, a second diffraction region (2b) included in the diffracting element for directing a reflected ray of the main beam reflected from the recording medium onto a main light receiving element and directing reflected rays of the sub-beams onto sub-light receiving elements, and an arithmetic circuit (not shown) for detecting a tilt error signal showing the sub-beam's focusing condition according to the output of the sub-light receiving elements, whereby an optical pickup device does not require installment of any separate tilt sensor for detection of a tilt signal, and also enables prevention of increasing the number of components and the increase of cost as a result of increased assembly steps and/or the required man-hours.
Inventors
- 👤 Taizo Yokota
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-24 22:17
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/12; G11B7/13; G11B7/08; G11B7/09; G11B7/095; G11B7/0956; G11B7/135; G11B7/1353; G11B7/0908; G11B7/0916
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
164 words
An optical pickup device for focusing an irradiating ray from a light emitting element on a recording medium and letting a reflected ray reflected by this recording medium focus on a light receiving element comprising: a diffracting element disposed before said light emitting element and said light receiving element; at least a first diffraction region included in said diffracting element for separating said irradiating ray from said light emitting element into a main beam and sub-beams shifted from said main beam in a direction perpendicular to a track direction of the track where said main beam is focused; a second diffraction region included in said diffracting element for directing a reflected ray of said main beam reflected from said recording medium onto a main light receiving element and directing reflected rays of said sub-beams onto sub-light receiving elements; and an arithmetic circuit for detecting a tilt error signal showing the focusing condition of said sub-beams according to the output of said sub-light receiving elements.
Claim 2
Dependent Claim
164 words
An optical pickup device for focusing an irradiating ray from a light emitting element on a recording medium and letting a reflected ray reflected by this recording medium focus on a light receiving element comprising: a diffracting element disposed before said light emitting element and said light receiving element; at least a first diffraction region included in said diffracting element for separating said irradiating ray from said light emitting element into a main beam and sub-beams shifted from said main beam in a direction perpendicular to a track direction of the track where said main beam is focused; a second diffraction region included in said diffracting element for directing a reflected ray of said main beam reflected from said recording medium onto a main light receiving element and directing reflected rays of said sub-beams onto sub-light receiving elements; and an arithmetic circuit for detecting a tilt error signal showing the focusing condition of said sub-beams according to the output of said sub-light receiving elements.
Claim 3
Dependent Claim
20 words
An optical pickup device according to claim 1 wherein said diffracting element is divided into a plurality of diffraction regions.
Claim 4
Dependent Claim
41 words
An optical pickup device according to claim 2 wherein said diffraction region is so formed that 0th-order diffraction efficiencies for said individual diffraction regions are substantially equal so that a distribution of the luminous intensity of the main beam is symmetrical.
Claim 5
Dependent Claim
43 words
An optical pickup device according to claim 1 wherein said diffracting element comprises one of the divided diffraction regions as a second diffraction region, a first diffraction region and a third diffraction region into which the other divided diffraction region is further divided.
Claim 6
Dependent Claim
39 words
An optical pickup device according to claim 4 wherein said first diffraction region is provided with a diffracting grating for separating the irradiating ray released from said light emitting element into a 0th-order diffracted ray and ±1st-order diffracted rays.
Claim 7
Dependent Claim
56 words
An optical pickup device according to claim 4 wherein said third diffraction region is provided with a diffracting grating for separating the irradiating ray released from said light emitting element into a 0th-order diffracted ray and ±1st-order diffracted rays shifted back and forth from said 0th-order diffracted ray along a track direction of the recording medium.
Claim 8
Dependent Claim
22 words
An optical pickup device according to claim 4 wherein said second diffraction region is provided with the properties of a cylindrical lens.
Claim 9
Dependent Claim
27 words
An optical pickup device according to claim 1 comprising a diffracting element, a collimator lens, an objective lens, a light receiving element and a light emitting element.
Claim 10
Dependent Claim
34 words
An optical pickup device according to claim 8 wherein said light receiving element comprises a main light receiving element and a plurality of sub-light receiving elements for detecting a tilt error and the like.
Claim 11
Dependent Claim
47 words
An optical pickup according to claim 9 wherein said plural sub-light receiving elements comprise a plurality of tilt error detection sub-light receiving elements for detecting a tilt of said recording medium by a warp of the like and a plurality of tracking error detection sub-light receiving elements.
Claim 12
Dependent Claim
45 words
An optical pickup device according to claim 9 wherein said main light receiving element is divided into two regions and is so formed that the reflected ray of said sub-beam diffracted in said second diffraction region is focused onto the center of the parting line.
Claim 13
Dependent Claim
50 words
An optical pickup device according to claim 10 wherein said tilt error detection sub-light receiving element is divided into two regions and is so formed that a reflected ray of a tilt error detection sub-beam diffracted in said second diffraction region is focused onto the center of the parting line.
Claim 14
Dependent Claim
44 words
An optical pickup device according to claim 10 wherein said tracking error detection sub-light receiving elements have one light receiving region respectively and be so formed that reflected rays of respective tracking error detection sub-beams diffracted in said second diffracting region are focused thereon.
Claim 15
Dependent Claim
37 words
An optical pickup device according to claim 1 wherein said arithmetic circuit comprises a subtraction circuit so that a tilt error signal is obtained according to the output signal from said tilt error detection sub-light receiving element.
Claim 16
Dependent Claim
26 words
An optical pickup device according to claim 1 wherein said arithmetic circuit comprises a signal detecting circuit composed of an addition circuit and a subtraction circuit.
Claim 17
Dependent Claim
46 words
An optical pickup device according to claim 1 wherein said diffracting element comprises at least a diffraction region for separating said tilt error detection sub-beam and a diffraction region for letting said tilt error detection sub-beam focus on a predetermined tilt error detection sub-light receiving element.
Claim 18
Dependent Claim
30 words
An optical pickup device according to claim 1 wherein said diffracting element is provided with the properties of a condensing lens for condensing a reflected ray or an irradiating ray.
Claim 19
Dependent Claim
94 words
An optical pickup device according to claim 1 wherein said diffracting element comprises a fourth diffracting region for focusing the reflected ray of said main beam on said light receiving element to detect a reproduced information signal, provided between said first diffraction region for separating the tilt error detection sub-beam and said third diffraction region; and said second diffraction region divided into three diffraction regions, each region for letting the reflected rays of said main beam, said tilt error detection sub-beam and said tracking error detection sub-beam respectively focus on individual light receiving elements.
Claim 20
Dependent Claim
114 words
An optical pickup device for reading information formed in a track or tracks on an optical recording medium by focusing light from a light source onto the medium and detecting light reflected from the track, wherein a diffraction element interposed between the light source forms a main beam and sub-beams shifted with respect to the main beam in a direction transverse to the track direction, and wherein a detector assembly includes a main detector for receiving the reflected main beam and sub-detectors spaced from the main detector in said transverse direction for receiving the reflected sub-beams, means being provided for deriving from the outputs of said sub-detectors a signal representing tilt of the medium.
Claim 21
Dependent Claim
114 words
An optical pickup device for reading information formed in a track or tracks on an optical recording medium by focusing light from a light source onto the medium and detecting light reflected from the track, wherein a diffraction element interposed between the light source forms a main beam and sub-beams shifted with respect to the main beam in a direction transverse to the track direction, and wherein a detector assembly includes a main detector for receiving the reflected main beam and sub-detectors spaced from the main detector in said transverse direction for receiving the reflected sub-beams, means being provided for deriving from the outputs of said sub-detectors a signal representing tilt of the medium.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.