# US 7,609,606 B2 · Optical pickup device

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- Number: US 7,609,606 B2
- Document ID: US7609606B2
- Status: Granted
- Kind: B2
- Application number: 11/302,343
- Filed: 2005-12-14
- Published: 2006-06-29
- Granted: 2009-10-27
- Earliest claimed: 2004-12-28
- Assignees: Sanyo Electric Co., Ltd.
- Inventors: Kenji Nagatomi; Seiji Kajiyama; Yoichi Tsuchiya
- Web page: https://patentgrep.com/patent/US7609606B2

## CPC

- G11B 7/1381: Non-lens elements for altering the properties of the beam, e.g. knife edges, slits, filters or stops (G11B7/1353 - G11B7/1369 take precedence)
- G11B 7/123: Integrated head arrangements, e.g. with source and detectors mounted on the same substrate
- G11B 7/1275: Two or more lasers having different wavelengths
- G11B 7/1353: Diffractive elements, e.g. holograms or gratings {(diffraction gratings per se G02B5/18; holograms per se G02B5/32; grating systems G02B27/44)}
- G11B 7/1365: Separate or integrated refractive elements, e.g. wave plates
- G11B 7/1378: Separate aberration correction lenses; Cylindrical lenses to generate astigmatism; Beam expanders
- G11B 7/1398: Means for shaping the cross-section of the beam, e.g. into circular or elliptical cross-section
- G11B 2007/0006: {adapted for scanning different types of carrier, e.g. CD & DVD}
- G11B 2007/13727: {Compound lenses, i.e. two or more lenses co-operating to perform a function, e.g. compound objective lens including a solid immersion lens, positive and negative lenses either bonded together or with adjustable spacing}
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)

## Abstract

Provided is an optical pickup device capable of suppressing an increase in the number of parts and complication of an optical system while a diffraction grating is used as an optical axis correcting element. Three kinds of blue, red, and infrared laser light beams are emitted from laser element provided in the same CAN package. A blue light emitting point (wavelength: 405 nm) and an infrared light emitting point (wavelength: 780 nm) are arranged in a layer forming direction of the laser elements such that an interval (d2) between the light emitting points becomes shorter than an interval (d1) between each of the light emitting points and a red light emitting point. An optical axis of the laser light beam emitted from the red light emitting point (wavelength: 650 nm) is aligned with an optical axis of the laser light beam emitted from the blue or infrared light emitting point by using the diffraction grating. The number of diffraction gratings for optical axis correction can be made to one and a single photo detector can be commonly used for laser light beams having different wavelengths.

## Claims

### Claim 1

An optical pickup device, comprising:
three laser elements provided in a CAN package, for emitting three kinds of laser light beams of blue, red, and infrared light beams to a recording medium, a blue light emitting point and an infrared light emitting point being arranged in a layer forming direction of the laser elements so that an interval (d2) between the blue light emitting point and the infrared light emitting point becomes smaller than an interval (d1) between one of the blue light emitting point and the infrared light emitting point and a red light emitting point; and
a diffraction grating for aligning an optical axis of a laser light beam emitted from the red light emitting point with an optical axis of a laser light beam emitted from one of the blue light emitting point and the infrared light emitting point.

### Claim 2 (depends on 1)

An optical pickup device according to claim 1, wherein the diffraction grating is located on one of a first optical path and a second optical path, the first optical path leading from one of the blue, red, and infrared light emitting points to the objective lens, the second optical path being an optical path which leads from the objective lens to the photo detector and is not overlapped with the first optical path leading from the one of the blue, red, and infrared light emitting points to the objective lens.

### Claim 3 (depends on 1)

An optical pickup device according to claim 1, further comprising a parallel plate for aligning the optical axis of the laser light beam emitted from the blue light emitting point with the optical axis of the laser light beam emitted from the infrared light emitting point.

### Claim 4 (depends on 3)

An optical pickup device according to claim 3, wherein the interval (d2) between the blue light emitting point and the infrared light emitting point is set in a range between about 20 μm and a minimum limit value of the interval between the blue light emitting point and the infrared light emitting point in a case where the blue light emitting point and the infrared light emitting point are arranged in the layer forming direction of the laser elements.

### Claim 5 (depends on 4)

An optical pickup device according to claim 4, wherein when the parallel plate is tilted 45.degree. relative to the optical axes of the blue light beam and the infrared light beam, the interval (d2) between the blue light emitting point and the infrared light emitting point is set in a range between about 10 μm and a minimum limit value of the interval between the blue light emitting point and the infrared light emitting point in the case where the blue light emitting point and the infrared light emitting point are arranged in the layer forming direction of the laser elements.

### Claim 6 (depends on 3, 4, 5)

An optical pickup device according to any one of claims 3 to 5, wherein the parallel plate is located on one of a first optical path and a second optical path, the first optical path leading from one of the blue, red, and infrared light emitting points to the objective lens, the second optical path being an optical path which leads from the objective lens to the photo detector and is not overlapped with the first optical path leading from the one of the blue, red, and infrared light emitting points to the objective lens.

### Claim 7 (depends on 6)

An optical pickup device according to claim 6, wherein the parallel plate is located on an optical path in which a laser light beam becomes parallel light.

### Claim 8

An optical pickup device, comprising:
a semiconductor laser including three laser elements provided in a CAN package, for generating three kinds of laser light beams including a laser light beam for next-generation DVD, a laser light beam for DVD, and a laser light beam for CD, a first light emitting point of the laser light beam for next-generation DVD and a second light emitting point of the laser light beam for CD being arranged in a layer forming direction of the laser elements so that an interval (d2) between the first light emitting point and the second light emitting point becomes smaller than an interval (d1) between one of the first light emitting point and the second light emitting point and a third light emitting point of the laser light beam for DVD; and
a diffraction grating for aligning an optical axis of the laser light beam for DVD with one of an optical axis of the laser light beam for next-generation DVD and an optical axis of the laser light beam for CD.

### Claim 9 (depends on 8)

An optical pickup device according to claim 8, wherein the diffraction grating is located on one of a first optical path and a second optical path, the first optical path leading from one of the first, second, and third light emitting points to the objective lens, the second optical path being an optical path which leads from the objective lens to the photo detector and is not overlapped with the first optical path leading from the one of the first, second, and third light emitting points to the objective lens.

### Claim 10 (depends on 8)

An optical pickup device according to claim 8, further comprising a parallel plate tilted relative to the optical axis of the laser light beam for next-generation DVD and the optical axis of the laser light beam for CD, for aligning the optical axis of the laser light beam for next-generation DVD and the optical axis of the laser light beam for CD with each other by refractive action.

### Claim 11 (depends on 10)

An optical pickup device according to claim 10, wherein the interval (d2) between the light emitting point for next-generation DVD and the light emitting point for CD is set in a range between about 20 μm and a minimum limit value of the interval between the blue light emitting point and the infrared light emitting point in a case where the light emitting point for next-generation DVD and the light emitting point for CD are arranged in the layer forming direction of the laser elements.

### Claim 12 (depends on 11)

An optical pickup device according to claim 11, wherein when the parallel plate is tilted 45.degree. relative to an optical axis, the interval (d2) between the light emitting point for next-generation DVD and the light emitting point for CD is set in a range between about 10 μm and a minimum limit value of the interval between the light emitting point for next-generation DVD and the light emitting point for CD in the case where the light emitting point for next-generation DVD and the light emitting point for CD are arranged in the layer forming direction of the laser elements.

### Claim 13 (depends on 10, 11, 12)

An optical pickup device according to any one of claims 10 to 12, wherein the parallel plate is located on one of a first optical path and a second optical path, the first optical path leading from one of the blue, red, and infrared light emitting points to the objective lens, the second optical path being an optical path which leads from the objective lens to the photo detector and is not overlapped with the first optical path leading from the one of the blue, red, and infrared light emitting points to the objective lens.

### Claim 14 (depends on 13)

An optical pickup device according to claim 13, wherein the parallel plate is located on an optical path in which a laser light beam becomes parallel light.