JP2011090785A - Optical pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pickup device provided with an easily manufactured element assembly. <P>SOLUTION: The optical pickup device 1 is equipped with: a diffraction grating part 10 which diffracts light; a holder part 20 having a space part 25 through which light can travel straight; and a film 30 which changes the polarization direction of light. The device includes an optical element assembly 50 which is formed by the combination of the holder part 20, diffraction grating part 10 and film 30. An air-passing part 26, which allows air to flow into/out of the space part 25 of the holder part 20 provided with the diffraction grating part 10 and the film 30, is provided in the holder part 20. The film 30 is formed by using a norbornene-based resin. The film 30 includes a reflection-preventing film 40. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical pickup device capable of reproducing data recorded on an optical disc and recording data on the optical disc.

  In recent years, various devices relating to an optical pickup device have been proposed. For example, a phase difference element and an optical element that can compensate for wavelength fluctuations of light emitted from a semiconductor laser due to temperature and can obtain a predetermined phase difference stably even in a high temperature range have been proposed (for example, , See Patent Document 1). In addition, an optical head device including the phase difference element and the optical element has been proposed (see, for example, Patent Document 1). The phase difference element is configured by applying an adhesive to the surface of an organic thin film having a phase difference generating function and bonding a fixed substrate having a transmission or reflection function to the organic thin film by the adhesive.

  In addition, for example, in an optical head device using two or more different wavelengths of laser light as a light source, an optical head device including a broadband retardation plate capable of converting two linearly polarized lights having different wavelengths into circularly polarized light has been proposed. (For example, refer to Patent Document 2). The broadband retardation plate is configured by bonding a birefringent film to a glass substrate via an adhesive layer.

Japanese Unexamined Patent Publication No. 2000-310718 (Pages 1, 2 and 1-5) JP 2001-101700 A (pages 1, 3 and 1-7)

  However, in the conventional phase difference element and optical element, it has been difficult to manufacture the phase difference element and the optical element with high accuracy and efficiency. When an adhesive is applied to the surface of an organic thin film having a phase difference generation function and a fixed substrate having a transmission or reflection function is adhered to the organic thin film to form a retardation element, the organic thin film and the fixed substrate In the meantime, for example, when a uniform adhesive layer is not formed, there is a concern that light transmission distortion may occur in the retardation element. A retardation element in which light transmission distortion occurs is handled as a defective product. If the phase difference element or the optical element including the phase difference element is not manufactured with high accuracy and efficiency, the yield of the phase difference element or the optical element is lowered, so that the price of the phase difference element or the optical element is increased.

  Further, even in the optical head device provided with the conventional broadband retardation plate, it has been difficult to manufacture the broadband retardation plate accurately and efficiently. When a broadband retardation plate is formed by adhering a birefringent film to a glass substrate with the adhesive layer interposed in the glass substrate, for example, a uniform adhesive layer is formed between the glass substrate and the birefringent film. When the film is not formed, there is a concern that light transmission distortion may occur in the broadband retardation plate. A broadband retardation plate in which light transmission distortion occurs is treated as a defective product. If the broadband retardation plate is not manufactured accurately and efficiently, the yield of the broadband retardation plate is lowered, and the price of the broadband retardation plate is increased.

  For this reason, there has been a concern that the price of an optical head device including a phase difference element and an optical element and an optical head device including a broadband phase difference plate will increase. In order to provide an optical head device, a so-called optical pickup device, at low cost, an optical pickup device including an easily manufactured optical element is required. For example, when an optical system element in which a uniform adhesive layer is not formed is equipped in an optical pickup device, there is a concern that an operation failure may occur in the optical pickup device.

  The present invention is to solve the above-described problems. An object of the present invention is to provide an optical pickup device including an optical element assembly that can be easily manufactured.

  In order to achieve the above object, an optical pickup device according to claim 1 of the present invention includes a diffraction grating portion that diffracts light, a holder portion provided with a space portion through which the light can travel straight, and a polarization direction of the light. An optical pickup device comprising a film that changes the optical element assembly, the optical element assembly including the holder part, the diffraction grating part, and the film.

  An optical pickup device according to a second aspect of the present invention is the optical pickup device according to the first aspect, wherein a ventilation portion that allows inflow / outflow of air into the space portion of the holder portion provided with the diffraction grating portion and the film. Is provided in the holder portion.

  An optical pickup device according to a third aspect is the optical pickup device according to the first or second aspect, wherein the film is formed using a norbornene resin.

  An optical pickup device according to a fourth aspect is the optical pickup device according to any one of the first to third aspects, wherein an antireflection film is provided on the film.

  As described above, according to the first aspect of the present invention, it is possible to provide an optical pickup device having an easily assembled optical element assembly. For example, in a conventional optical system element in which an adhesive is used and a film is surface-bonded to a diffraction grating, if the thickness of the adhesive layer is not uniform, light transmission distortion occurs in the optical system element. There was concern about what would happen. However, the optical element assembly is configured by combining a diffraction grating part for diffracting light and a film for changing the polarization direction of light with a holder part provided with a space part through which light can travel straight. If so, the optical element assembly is easily and accurately manufactured. Light transmission distortion caused by the thickness of the adhesive layer by combining a diffraction grating part that diffracts light and a film that changes the polarization direction of light into a holder part provided with a space where light can travel straight. Occurrence of a problem that occurs in the optical element assembly is avoided. Since it is easy to manufacture an optical element assembly that avoids the generation of light transmission distortion, the price of the optical pickup device including the optical element assembly can be kept low.

  According to the second aspect of the present invention, the optical pickup device functions without being affected by the temperature change. When the temperature change occurs in the optical pickup device when the space part of the holder part provided with the diffraction grating part and the film and the outside of the holder part are not communicated by the ventilation part, the holder part is provided. There is a concern that the film of the optical element assembly may be deformed by the compression / expansion of the air in the space. When the film of the optical element assembly is deformed, the light transmitted through the film is not in a normal state, and there is a concern that the optical pickup device may malfunction due to the deformed film. If a ventilation part that allows inflow / outflow of air is provided between the space part of the holder part provided with the diffraction grating part and the film and the outside of the holder part, the temperature of the optical pickup device is affected. Thus, it is avoided that the film of the optical element assembly is deformed and a problem occurs in the optical pickup device.

  According to the invention of claim 3, the optical element assembly with a film suitable for the specification of the optical pickup device can be easily assembled. The norbornene-based resin used as a film material is excellent in optical properties, heat resistance, and low water absorption. The norbornene-based resin has high transparency and low distortion, and is excellent in optical characteristics. Norbornene-based resins have a heat distortion temperature of about 164 ° C. and are excellent in heat resistance. Further, the norbornene-based resin has a water absorption rate that is, for example, about one-fifth that of an acrylic resin, and is small in dimensional change due to water absorption. An excellent optical element assembly with a film is easily assembled, and this optical element assembly is mounted on an optical pickup device, whereby an optical pickup device having an excellent function is configured.

  According to the fourth aspect of the present invention, an optical element assembly with a film that is optimal for an optical pickup device can be easily assembled. By providing an antireflection film on the film that changes the polarization direction of the light, a part of the light transmitted through the film is reflected, thereby preventing the occurrence of a malfunction that the optical pickup device does not function normally. . Therefore, an optical pickup device that can exhibit an excellent optical function is configured.

It is a disassembled perspective view which shows one Embodiment of the optical element assembly of the optical pick-up apparatus which concerns on this invention. It is a perspective view which shows the optical element assembly of an optical pick-up apparatus. (A) is explanatory drawing which shows the optical element assembly of an optical pick-up apparatus, (B) is SS sectional drawing of A, (C) is a side view which shows the optical element assembly of an optical pick-up apparatus. It is explanatory drawing which shows the optical element assembly of an optical pick-up apparatus.

  Hereinafter, an embodiment of an optical pickup device according to the present invention will be described in detail with reference to the drawings.

  1 to 4 show an embodiment of an optical element assembly of an optical pickup device according to the present invention.

  The optical pickup device 1 includes a light emitting element (not shown) that emits laser light, a diffraction grating 10 that diffracts the laser light, and an objective lens (not shown) that narrows the laser light and irradiates an optical disk (not shown). 2), a lens holder (not shown) attached with an objective lens and movable up and down, left and right, and a photodetector that converts a signal of the laser beam reflected from the optical disk into an electrical signal.

  The laser light emitted from the light emitting element of the optical pickup device 1 passes through each optical component such as the diffraction grating 10, is then focused by the objective lens, and is condensed on the signal layer of the optical disc. Further, the laser light reflected from the optical disk enters the photodetector after passing through each optical component. The photodetector receives the laser beam reflected from the optical disc, converts the signal into an electrical signal, and detects data / information recorded on the optical disc. The photodetector receives the laser beam reflected from the optical disk, converts the signal into an electrical signal, and operates a servo mechanism (not shown) of the lens holder with an objective lens constituting the optical pickup device 1. .

  Further, the optical pickup device 1 includes a glass diffraction grating 10 that diffracts laser light, a resin holder 20 provided with a space 25 in which the laser light can travel straight, and a polarization direction of linearly polarized laser light. And a resin film 30 that changes the thickness.

  The surface 12 on the film 30 side of the glass diffraction grating 10 has a fine concavo-convex repeating periodic structure. Since the surface 12 on the film 30 side of the glass diffraction grating 10 has a fine concavo-convex repetitive periodic structure, at least three laser beams emitted from a light emitting element such as a laser diode (not shown) can be obtained. Divided into luminous flux. A side surface 11 opposite to the film 30 side surface 12 of the diffraction grating 10 is formed as a glossy smooth surface 11. The diffraction grating 10 functions as a grating that divides laser light into a plurality of light beams. Depending on the design / specifications of the optical pickup device 1, the diffraction grating 10 may be formed of, for example, a resin material.

  Further, the resin holder 20 is formed by using polycarbonate having excellent heat resistance, mechanical strength, dimensional stability, and moldability. The resin / plastic holder 20 is manufactured based on an injection molding method with excellent mass productivity. In order to eliminate the influence of light on other parts, the resin / plastic holder 20 is black.

  Depending on the design / specifications of the optical pickup device 1, for example, a thermoplastic synthetic resin material such as polycarbonate that can be injection-molded is used, and the diffraction grating portion 10 and the holder portion 20 are integrally molded based on an injection molding method. Can also be used. Examples of the polycarbonate resin include Panlite (registered trademark) manufactured by Teijin Chemicals Limited. Specific polycarbonate resin trade names include, for example, Panlite AD-5503 manufactured by Teijin Chemicals Limited.

  The resin film 30 is formed by stretching a polyolefin resin film. The polyolefin film 30 functions as a half-wave plate that changes the polarization direction of linearly polarized laser light.

  The holder unit 20, the diffraction grating unit 10, and the film 30 are combined to form an optical element assembly. More specifically, an optical adhesive is used, the diffraction grating 10 and the film 30 are attached to the holder 20, and one optical element assembly 50 is assembled. A film 30 is attached to the opposite side of the holder 20 to which the diffraction grating 10 is attached. The optical pickup device 1 is configured by combining a diffraction grating 10 that divides laser light into three light beams, a film 30 that functions as a half-wave plate, and a holder 20 to which the diffraction grating 10 and the film 30 are attached. The optical element assembly 50 is provided.

  Use of the diffraction grating 10 having the structure shown in FIGS. 1 to 4, the film 30, and the holder 20 makes it possible to provide the optical pickup device 1 having the optical element assembly 50 that is easily assembled. For example, in a conventional optical system element (not shown) in which an adhesive is used and a film is surface-bonded to a diffraction grating, if the thickness of the adhesive layer is not formed uniformly, There has been a concern that light transmission distortion may occur.

  However, the optical element assembly 50 can be obtained by combining the diffraction grating portion 10 that diffracts light and the film 30 that changes the polarization direction of light with the holder portion 20 provided with the space portion 25 that allows light to travel straight. If configured, the optical element assembly 50 is easily and accurately manufactured. More specifically, the adhesive 20 is used to change the polarization direction of the linearly polarized laser beam to the diffraction grating 10 that diffracts the laser beam and the holder 20 having the space portion 25 in which the laser beam can travel straight. If the optical element assembly 50 is manufactured by attaching the film 30 to be manufactured, the assembly / manufacturing operation of the optical element assembly 50 can be performed without maintaining the thickness of the adhesive layer with high accuracy. Done easily.

  By attaching the diffraction grating part 10 for diffracting the laser light and the film 30 for changing the polarization direction of the linearly polarized laser light to the holder part 20 provided with the space part 25 capable of linearly traveling the laser light, the adhesive layer The occurrence of inconvenience that the transmission distortion of the laser beam due to the thickness of the optical element assembly 50 occurs is avoided. Since the optical film 30 is bonded to the periphery of the space portion 25 of the holder portion 20, laser light transmission distortion due to the adhesive layer does not occur on the light transmission surfaces 31 and 32 of the film 30. Since the assembly / manufacturing operation of the optical element assembly 50 in which generation of laser light transmission distortion is avoided is easily performed with a high yield, the price of the optical pickup device 1 including the optical element assembly 50 can be kept low.

  The holder part 20 is provided with a ventilation part 26 that allows air to flow into / out of the space part 25 of the holder part 20 provided with the diffraction grating part 10 and the film 30. More specifically, the holder 20 is formed with a ventilation portion 26 that allows air to flow in / out in the space 25 of the holder 20 to which the diffraction grating 10 and the film 30 are attached.

  Thereby, the optical pickup device 1 functions normally without being influenced by the temperature change in the optical pickup device 1. When a temperature change occurs in the optical pickup device 1 when the space portion 25 of the holder portion 20 provided with the diffraction grating portion 10 and the film 30 and the outside 29 of the holder portion 20 are not communicated by the ventilation portion 26. Furthermore, there is a concern that the film 30 of the optical element assembly 50 may be deformed due to the compression / expansion of the air in the space portion 25 provided in the holder portion 20. When the film 30 of the optical element assembly 50 is deformed, the laser light transmitted through the film 30 is not in a normal state, and there is a concern that the optical pickup device 1 may malfunction due to the deformed film 30. Is done. If a ventilation part 26 that allows inflow / outflow of air is provided between the space part 25 of the holder part 20 provided with the diffraction grating part 10 and the film 30 and the outside 29 of the holder part 20, It is avoided that the film 30 of the optical element assembly 50 is deformed due to the temperature of the optical pickup device 1 and a problem occurs in the optical pickup device 1.

  The optical film 30 is formed using a norbornene heat-resistant transparent resin. This norbornene-based heat-resistant transparent resin is an amorphous polyolefin-based resin. The norbornene-based heat-resistant transparent resin film 30 is formed by stretching a resin molded film.

  By using the film 30 made of norbornene heat-resistant transparent resin, the optical element assembly 50 with the film 30 suitable for the specifications of the optical pickup device 1 can be easily assembled. The norbornene-based heat-resistant transparent resin used as the material of the film 30 is excellent in optical characteristics, heat resistance, low water absorption, adhesion, and the like.

  Norbornene-based heat-resistant transparent resin has high transparency and low distortion, and has excellent optical properties. For example, when the norbornene-based heat-resistant transparent resin film 30 is irradiated with laser light having a wavelength of about 830 nm (nanometer), the light transmittance is about 91%. The norbornene-based heat-resistant transparent resin film 30 is excellent in in-plane uniformity of retardation. The film 30 made of norbornene-based heat-resistant transparent resin has a small wavelength dependency of retardation, and generates a substantially uniform retardation at any wavelength.

  Further, the norbornene-based heat-resistant transparent resin has a heat distortion temperature of about 164 ° C. and a glass transition point of about 171 ° C., and is excellent in heat resistance. Further, the norbornene-based heat-resistant transparent resin has a water absorption rate of about one-fifth that of an acrylic resin, for example, and has a small dimensional change due to water absorption. The saturated water absorption of the norbornene heat-resistant transparent resin is about 0.4% (weight%). Moreover, since norbornene-type heat-resistant transparent resin is excellent in adhesiveness etc., norbornene-type heat-resistant transparent resin molding is reliably fixed to a counterpart material with an adhesive. The norbornene-based heat-resistant transparent resin is excellent in adhesive strength. Even when stress such as heat, humidity, and adhesion is applied to the norbornene-based heat-resistant transparent resin film 30, the norbornene-based heat-resistant transparent resin film 30 does not change in retardation.

  The optical element assembly 50 with the film 30 having excellent characteristics is easily assembled, and the optical element assembly 50 is provided in the optical pickup apparatus 1, whereby the optical pickup apparatus 1 having excellent functions. Is configured. Examples of the norbornene-based heat-resistant transparent resin include JSR Corporation: Arton / ARTON (registered trademark).

  An antireflection film 40 is provided on the optical film 30.

  Thereby, the optical element assembly 50 with the retardation film 30 optimal for the optical pickup device 1 is easily assembled. By providing the anti-reflection film 40 on the film 30 that changes the polarization direction of the laser light, a part of the light transmitted through the film 30 is reflected, and this causes a problem that the optical pickup device 1 does not function normally. Occurrence is avoided. Therefore, the optical pickup device 1 that can exhibit an excellent optical function is configured.

When forming the antireflection film 40 on the film 30, the antireflection film 40 is formed on the film 30 by, for example, AR coating. For example, magnesium fluoride (MgF ₂ ) or the like is vacuum-deposited on both light transmitting surfaces 31 and 32 of the film 30 to form the transparent thin film 40. By forming a transparent thin film 40 and utilizing interference of light, other light is canceled.

  For example, when other light is applied to the film 30 toward the light transmitting surface 31 or 32 of the film 30, the light reflected by the surface of the film 40 provided on the film 30 and the film 40 provided on the film 30 are changed. The light is transmitted and reflected at the back of the film 40. The light reflected from the surface of the film 40 and the light transmitted through the film 40 and reflected from the back of the film 40 have opposite phases that are shifted by ½ wavelength. Therefore, the light reflected from the surface of the film 40 and the light transmitted through the film 40 and reflected from the back of the film 40 cancel each other.

  Depending on the design / specifications of the optical pickup device 1, for example, the antireflection film 40 may be formed only on the first light transmission surface 31 of the film 30. Further, for example, the antireflection film 40 may be formed only on the second light transmission surface 32 of the film 30 depending on the design / specifications of the optical pickup device 1.

  An adhesive (not shown) that fixes the diffraction grating 10 to the holder 20 is used to bond the diffraction grating 10 to the holder 20. The diffraction grating 10 is easily fixed to the holder 20 by the adhesive. Further, an adhesive that fixes the film 30 to the holder 20 is used, and the film 30 is bonded to the holder 20. The film 30 is easily fixed to the holder 20 by the adhesive.

  An adhesive is applied to the attachment portion 23 of the holder 20, and the film 30 is adhered to the holder 20 while the attachment portion 33 of the film 30 is adjusted to rotate relative to the attachment portion 23 of the holder 20. Alternatively, the adhesive is applied to the side surface 31 of the diffraction grating 10 of the mounting portion 33 of the film 30, and the film 30 is bonded to the holder 20 while the mounting portion 33 of the film 30 is rotated and adjusted with respect to the mounting portion 23 of the holder 20. Is done. The attachment portion 23 of the holder 20 is formed by denting the film 30 into a shape that can be rotated. By attaching the attachment portion 33 of the film 30 to the attachment portion 23 of the holder 20, the film 30 side of the space portion 25 of the holder 20 is closed by the film 30.

  The film 30 is fixed to the holder 20 by spotting and bonding the film 30 to the holder 20. For example, the film 30 is fixed to the holder 20 by spotting and attaching the attachment portion 33 of the film 30 to the attachment portion 23 of the holder 20. An adhesive may be spotted on other parts than the attachment part 33 of the film 30. By performing spot adhesion, the film 30 is fixed to the holder 20 with a small amount of adhesive. Since the amount of adhesive used can be reduced, the price of the optical pickup device 1 can be kept low.

  The optical element assembly 40 is manufactured in this way. The assembled optical element assembly 40 is attached to a housing (not shown) constituting the optical pickup device 1.

  The laser light emitted from the laser diode passes through the optical element assembly 40 mounted on the housing. The laser light incident on one surface 11 of the diffraction grating 10 is transmitted through the diffraction grating 10 and emitted from the other surface 12 of the diffraction grating 10, passes through the space portion 25 in the holder 20, and passes through the space 30 of the film 30. The light passes through the antireflection film 40 provided on one surface 31, passes through the film 30, and passes through the antireflection film 40 provided on the other surface 32 of the film 30 to be emitted.

  The optical pickup device of the present invention is not limited to the illustrated one. The optical pickup device of the present invention can be variously modified without departing from the gist thereof.

1 Optical pickup device 10 Diffraction grating (Diffraction grating part)
11, 12 Surface (surface)
20 Holder (holder part)
23, 33 Mounting portion 25 Space portion 26 Ventilation portion 29 External 30 Optical film (film)
31, 32 Light transmission surface (surface)
40 Anti-reflective coating (film)
50 Optical element assembly

Claims (4)

A diffraction grating part for diffracting light;
A holder part provided with a space part through which the light can travel straight;
An optical pickup device comprising a film that changes the polarization direction of the light,
An optical pickup device comprising an optical element assembly configured by combining the holder portion, the diffraction grating portion, and the film.   The optical pickup according to claim 1, wherein a vent portion that allows air to flow in / out of the space portion of the holder portion provided with the diffraction grating portion and the film is provided in the holder portion. apparatus.   3. The optical pickup device according to claim 1, wherein the film is formed using a norbornene resin.   The optical pickup device according to claim 1, wherein an antireflection film is provided on the film.

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