EP0545905A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Optical pickup element

Assignee: Sony Corp

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Filing: 1988-07-25

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Granted: —

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Expires: 2008-07-25

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Abstract

Abstract An optical pickup device having a semiconductor laser element (5) mounted on a substrate (2), a photo detector (3) formed on the substrate to receive a laser beam emitted from the semi-conductor laser element (2) and an optical element (6) mounted on the substrate to cover the photo detector to branch the direction of optical path of the laser beam. The optical element (6) is adapted to reduce the amount of unwanted stray light from the laser (5) reaching the photo detector (3). The rear face (6f) of the element (6) is coated with light absorption material (14) to substantially prevent said incident light from being reflected into the photo detector (3). The light absorption material (14) is chosen to absorb light of the wavelength(s) emitted by the laser element. The material (14) preferably has the same refractive index as the element (6).

Inventors

👤 You Yoshitoshi
👤 Yoshiyuki Matsumoto
👤 Hidehiro Kume
👤 Koji Mitsumori
👤 Etsufumi Yamamoto
👤 Hiroshi Oinoue

Bibliographic Details

Application Number —

Jurisdiction EP

Data Source google_patents

Last Synchronized 2026-11-03 11:57

CPC Classifications

G; G11; G11B; G11B7/00; G11B7/12; G11B7/135; G11B7/1359; G11B7/123; G11B7/1356; H; H01; H01S; H01S5/00; H01S5/02; H01S5/022; H01S5/023; H01S5/02325; H01S5/005; H01S5/06; H01S5/068; H01S5/0683

Claims Analysis

Total Claims: 6

Claim 1

Independent Claim 148 words

An optical pickup device comprising: (a) a substrate (2); (b) a semi-conductor laser element (5) mounted on said substrate (2); (c) a photo detector (3) for receiving a laser beam emitted from said semi-conductor laser element (5) mounted on said substrate (2); and (d) an optical path branching optical element (6) fixed to said substrate (2) over said photo detector (3), said optical element (6) including an inclined front face (6a) positioned opposite said laser element (5) and having a semi-transparent reflection film deposited thereon and a rear face (6f) positioned opposite said front face; characterised in that said rear face (6f) is coated with light absorption material (14) to substantially absorb light incident thereon to substantially prevent said incident light from being reflected into said photo detector (3), said light absorption material (14) being chosen to absorb light of the wavelength(s) emitted from said semi-conductor laser element.

Claim 2

Dependent Claim 34 words

A device as claimed in claim 1, wherein the optical path branching optical element (6) has left and right side faces (6d, 6e), said side faces also being coated with light absorption material (14).

Claim 3

Dependent Claim 42 words

A device as claimed in claim 1 or claim 2, wherein the optical path branching optical element (6) has an upper surface (6c), a portion of said upper surface adjacent to said rear face (6f) being coated with light absorption material (14).

Claim 4

Independent Claim 31 words

A device as claimed in any of the preceding claims, wherein the light absorption material (14) is applied to the optical path branching optical element (6) in a predetermined coating pattern.

Claim 5

Independent Claim 22 words

A device as claimed in any of the preceding claims, wherein the light absorption material (14) is black paint or the like.

Claim 6

Independent Claim 29 words

A device as claimed in any of the preceding claims, wherein said light absorption material (14) has the same refractive index as the optical path branching optical element (6).

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