WO2012039318A1

WO2012039318A1 - Optical pickup device and optical disc device

Info

Publication number: WO2012039318A1
Application number: PCT/JP2011/070811
Authority: WO
Inventors: 宏勲中原; 俊哉的崎; 伸夫竹下
Original assignee: 三菱電機株式会社
Priority date: 2010-09-24
Filing date: 2011-09-13
Publication date: 2012-03-29
Also published as: JPWO2012039318A1; CN203276837U

Abstract

An optical pickup device (104) is provided with a first optical integration element (201), which outputs a laser beam having a first oscillation wavelength, a second optical integration element (202), which outputs a laser beam having a second oscillation wavelength, a beam splitter (205), a parallel optical system (206), and a light collecting optical system (207). In a first optical path between the beam splitter (205) and the first optical integration element (201), a negative lens (204) having negative refractive power, and a total reflection mirror (203) are disposed. The focal point distance of the parallel optical system (206) is set to a value that minimizes, within a first predetermined range, rim light intensity with respect to the laser beam having the second oscillation wavelength, and the focal point distance of the negative lens (204) is set to a value that minimizes, within a second predetermined range, rim light intensity with respect to the laser beam having the first oscillation wavelength. The first optical integration element (201) is disposed at the end of the first optical path that is bent by the total reflection mirror (203), said first optical integration mirror being adjacent to the second optical integration element (202).

Description

Optical pickup device and optical disk device

The present invention relates to a technique for reproducing recorded information from an optical disc.

Optical discs such as CD (Compact Disc), DVD (Digital Versatile Disc: Digital Versatile Disc) or BD (Blu-ray Disc; registered trademark) enable non-contact information recording / reproduction, and have a large capacity and are relatively inexpensive. Therefore, it is widely used from industrial use to consumer use. To increase the capacity of optical discs, the recording marks (including pits and phase change marks) formed on the track-like or spiral-like recording tracks of the optical discs are miniaturized, and the lasers used for recording and reproduction are adjusted accordingly. This has been achieved by miniaturizing the focused spot size on the focal plane by shortening the wavelength of light and increasing the numerical aperture (NA) of the objective lens.

For example, in a CD, the thickness of a disk substrate serving as a light transmission layer is about 1.2 mm, the laser light wavelength is about 780 nm, the NA of the objective lens is 0.45, and a capacity of 650 MB can be realized. In a DVD, the thickness of a disk substrate serving as a light transmission layer is about 0.6 mm, the wavelength of a laser beam is about 650 nm, and the NA is 0.6, so that a capacity of 4.7 GB can be realized. In the case of a BD having a higher recording density, the thickness of the protective layer, which is a light transmission layer covering the optical recording layer, is reduced to about 0.1 mm, the laser beam wavelength is set to about 405 nm, and the NA is set to 0.85. The above increase in capacity can be realized.

In addition, optical discs are used in various scenes as they become popular. For this reason, devices that reproduce information from optical discs are required to be further miniaturized in order to improve portability and save space. In order to reduce the size of such a device, it is essential to reduce the size of the optical pickup device mounted on the device. For example, Japanese Patent Application Laid-Open No. 2010-102810 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2007-250123 (Patent Document 2) describe an optical pickup using an optical integrated element in which a light emitting element and a light receiving element are integrated. A technique for reducing the size of the apparatus is disclosed.

JP 2010-102810 A (paragraph 0011 etc.) JP 2007-250123 A

In recent years, there has been provided an optical pickup device capable of reproducing information from a plurality of types of optical disks having different standards such as DVD and BD. In this type of optical pickup device, multiple types of laser light sources (light emitting elements) with different oscillation wavelengths are mounted according to the type of optical disc, and optical components designed to correspond to the oscillation wavelengths of the laser light sources are mounted. Therefore, there is a problem that the number of optical parts increases. Japanese Patent Application Laid-Open No. 2004-151561 discloses a technique for reducing the size of an optical pickup device by employing an optical integrated element. However, there is a limit to the size reduction of the device by this technique.

As another method for miniaturization, as described in Patent Document 2, some optical components (for example, an objective lens and a collimator lens) are shared for a plurality of types of laser light sources, so that the number of optical components is increased. One way to reduce this is to consider. However, when the optical parts are shared, there is a problem that a desired reproduction performance can be obtained for some types of optical discs, but it is difficult to obtain a desired reproduction performance for other types of optical discs.

In view of the above, the object of the present invention is to mount a plurality of laser light sources having different oscillation wavelengths corresponding to a plurality of types of optical discs, even if some of the optical components are shared for these laser light sources. It is an object to provide an optical pickup device and an optical disc apparatus that can realize downsizing of the apparatus while ensuring good reproduction performance for various types of optical discs.

An optical pickup device according to a first aspect of the present invention includes a first optical integrated element including a first laser light source that emits laser light having a first oscillation wavelength and a first light receiving element, and the first oscillation wavelength. A second optical integrated element that includes a second laser light source that emits laser light having a longer second oscillation wavelength and a second light receiving element, a first optical surface, a second optical surface, and a third optical surface A laser beam having the first oscillation wavelength that is incident on the first optical surface from the first optical integrated element through the first optical path and is emitted from the third optical surface; And a beam splitter that guides the laser light having the second oscillation wavelength incident on the second optical surface from the second optical integrated element through the second optical path and emits the laser light from the third optical surface. And the first oscillation wavelength emitted from the third optical surface of the beam splitter A parallel optical system that converts laser light into first parallel light and converts laser light of the second oscillation wavelength emitted from the third optical surface into second parallel light; and A condensing optical system for condensing the emitted first parallel light on the optical disc and condensing the second parallel light emitted from the parallel optical system on the optical disc, and in the first optical path A negative lens having a negative refractive power that diverges the laser light having the first oscillation wavelength emitted from the first optical integrated device, and disposed in the first optical path. A total reflection mirror that reflects the laser beam having the first oscillation wavelength emitted from the optical integrated element in the direction of the first optical surface, and the return light reflected by the optical disc is the condensing optical system and the The beam spring passes through a parallel optical system. And the beam splitter guides the laser light having the first oscillation wavelength out of the return light and emits the laser light from the first optical surface. Among them, the laser beam having the second oscillation wavelength is guided and emitted from the second optical surface, and the first optical integrated element is emitted from the first optical surface and is emitted from the negative lens and the total reflection mirror. The second optical integrated element receives the laser light having the second oscillation wavelength emitted from the second optical surface, and receives the parallel optical. The focal length of the system is set to a value that minimizes the rim light intensity with respect to the laser light having the second oscillation wavelength within the first predetermined range, and the focal length of the negative lens is the same as that of the first oscillation wavelength. Rim light intensity against laser light is minimized within the second predetermined range The first optical integrated element is disposed at an end of the first optical path bent by the total reflection mirror, and is disposed adjacent to the second optical integrated element. It is characterized by.

An optical disc apparatus according to the second aspect of the present invention includes the optical pickup device.

According to the present invention, it is possible to reduce the size of the apparatus while ensuring good reproduction performance when using the first laser light source of the first optical integrated device.

1 is a functional block diagram schematically showing a configuration of an optical disc device according to a first embodiment of the present invention. (A), (B) is a figure which shows schematically the structure of the optical pick-up apparatus of Embodiment 1. FIG. FIG. 3 is a diagram schematically showing an optical path of DVD / CD laser light in the optical pickup device of the first embodiment. FIG. 3 is a diagram schematically showing an optical path of BD laser light in the optical pickup device of the first embodiment. (A) to (C) are diagrams for explaining the beam divergence angle. It is a graph which shows the rim light intensity of the radial direction with respect to the focal distance of the optical system which consists of a combination of a collimator lens and a negative lens. (A), (B) is a figure which shows schematically the structure of the optical pick-up apparatus of Embodiment 2 which concerns on this invention. FIG. 6 is a diagram schematically showing an optical path of a DVD / CD laser beam in the optical pickup device of the second embodiment. 6 is a diagram schematically showing an optical path of a BD laser beam in the optical pickup device of Embodiment 2. FIG. (A), (B) is a figure which shows schematically the structure of the optical pick-up apparatus of Embodiment 3 which concerns on this invention. (A), (B) is a figure which shows roughly the structure of the optical pick-up apparatus of Embodiment 4 which concerns on this invention.

Hereinafter, various embodiments according to the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a functional block diagram schematically showing the configuration of the optical disc apparatus 1 according to the first embodiment of the present invention. 2A and 2B are diagrams schematically showing a configuration of the optical pickup device 104 in the optical disc apparatus 1. FIG.

As shown in FIG. 1, the optical disc apparatus 1 includes a turntable 102 on which an optical disc 101 is detachably mounted, a spindle motor 103 as a disc drive unit that rotationally drives the turntable 102, and recording information from the optical disc 101. An optical pickup device 104 that reads the optical pickup device 104, and a sled drive mechanism 105 that shifts the optical pickup device 104 in the radial (radius) direction of the optical disc 101 and positions the optical pickup device 104. The optical disc apparatus 1 also includes a matrix circuit 106, a signal reproduction circuit 107, a servo circuit 108, a spindle control circuit 109, a laser control circuit 110, a thread control circuit 111, and a controller 112.

The optical disc 101 is detachably mounted on a turntable 102 fixed to a drive shaft (spindle) of the spindle motor 103. The optical disc 101 is a single layer disc having a single information recording layer or a multilayer disc having a plurality of information recording layers. Examples of the optical disc 101 include, but are not limited to, a CD (Compact Disc), a DVD (Digital Versatile Disc), and a BD (Blu-ray Disc). The spindle motor 103 rotates the optical disc 101 under the control of the spindle control circuit 109. The spindle control circuit 109 operates in accordance with a command from the controller 112, and executes a spindle servo so that the actual rotational speed matches the target rotational speed based on a pulse signal representing the actual rotational speed supplied from the spindle motor 103. Have

The optical pickup device 104 irradiates the optical disc 101 with laser light during information reproduction or recording, receives return light reflected by the information recording layer of the optical disc 101, generates a detection signal, and generates the detection signal as a matrix circuit. A function of outputting to 106. 2A is a top view when the optical pickup device 104 is viewed from the normal direction perpendicular to the information recording surface of the optical disc 101 (Z-axis direction perpendicular to the X-axis and Y-axis). FIG. 2B is a schematic diagram when a part of the optical pickup device 104 is viewed from the side (X-axis direction). As shown in FIGS. 2A and 2B, the optical pickup device 104 has a casing CS having a long side along the radial direction of the optical disc 101. Further, the optical pickup device 104 includes optical

integrated elements

201 and 202, a reflection mirror 203, a negative lens (concave lens) 204 having a negative refractive power, a dichroic prism 205 as a beam splitter, a collimator lens 206, an objective A lens actuator 209.

One optical integrated element 201 has a structure in which a semiconductor laser element emitting a BD laser beam (oscillation wavelength: about 405 nm) and a light receiving element are integrated on the same substrate, and the other optical integrated element 202 is: A two-wavelength semiconductor laser element that emits a laser beam for DVD (oscillation wavelength: about 650 nm) and a laser beam for CD (oscillation wavelength: about 780 nm) and a light receiving element are integrated on the same substrate. . The laser control circuit 110 can control the intensity of the laser light emitted from the optical pickup device 104 by individually driving these optical

integrated elements

201 and 202.

The laser light emitted from the optical integrated element 201 is reflected by the reflection mirror 203, passes through the negative lens 204, and enters the dichroic prism 205. The dichroic prism 205 reflects the laser light emitted from the negative lens 204 toward the collimator lens (parallel optical system) 206. On the other hand, the laser light emitted from the integrated optical element 202 passes through the dichroic prism 205 and enters the light incident surface of the collimator lens 206. As shown in FIG. 2B, the collimator lens 206 converts the laser light incident from the dichroic prism 205 into parallel light. As described above, the collimator lens 206 is an optical component shared for the BD laser beam, the DVD laser beam, and the CD laser beam.

As shown in FIG. 2B, the rising mirror 208 converts the direction of the parallel light incident from the collimator lens 206 into the direction of the compatible objective lens (condensing optical system) 207 (Z-axis direction). The compatible objective lens 207 condenses the light incident from the reflection surface of the rising mirror 208 on the optical disc 101. The compatible objective lens 207 is also an optical component shared for the BD laser beam, the DVD laser beam, and the CD laser beam. The optical surface (for example, the light incident surface on the light source side) of the compatible objective lens 207 has a diffraction grating structure having a wavelength selectivity (aperture limiting function) that selectively diffracts the incident light according to the wavelength range of the incident light. Thus, different NAs (numerical apertures) can be formed according to the wavelength range of incident light. In the present embodiment, the NA for the CD laser light is about 0.45, the NA for the DVD laser light is about 0.6, and the NA for the BD laser light is about 0.85. Table 1 below shows an example of the specification of the three-wavelength compatible objective lens 207 for BD / DVD / CD laser light.

In the compatible objective lens 207, the difference in the focal length of the objective lens is caused by the difference in the wavelength of the laser beam. Therefore, the difference in focal length due to the difference in laser light wavelength is small. The NA of the objective lens is designed to satisfy the specifications of BD, DVD, and CD. In this specification, the NA of the objective lens increases as the wavelength of the laser beam is shorter. As a result, the ratio of the objective lens pupil diameter to the BD, DVD, and CD laser light is substantially the same as the ratio of NA to the BD, DVD, and CD laser light. The larger the NA, the larger the objective lens pupil diameter, the larger the amount of laser light captured, and the more efficient the use of the laser light.

The optical pickup device 104 further includes a collimator lens driving mechanism 210 for correcting optical aberration (mainly spherical aberration). The collimator lens driving mechanism 210 can appropriately correct the optical aberration by shifting the collimator lens 206 in the optical axis direction in accordance with the control signal supplied from the servo circuit 108 or the controller 112. The collimator lens driving mechanism 210 has a stepping motor (not shown) and a guide mechanism (not shown) for moving the collimator lens 206 in the optical axis direction. The collimator lens driving mechanism 210 covers, for example, the thickness of a cover layer (layer that covers the information recording layer) corresponding to the type (DVD / CD / BD) of the optical disc 101, and a specific information recording layer in the multilayer disc. The spherical aberration can be corrected by shifting the collimator lens 206 along the optical axis in accordance with the thickness of the cover layer or the manufacturing error of the thickness of the cover layer.

Referring to FIG. 1, the matrix circuit 106 includes a matrix calculation circuit, an amplifier circuit, and the like, and performs a matrix calculation process on the detection signal supplied from the optical pickup device 104 to generate a reproduction RF signal that is a high-frequency signal. Further, servo control signals such as a focus error signal and a tracking error signal are generated. The reproduction RF signal is supplied to the signal reproduction circuit 107, and the servo control signal is supplied to the servo circuit 108.

The signal reproduction circuit 107 performs binarization processing on the reproduction RF signal to generate a modulation signal, extracts a reproduction clock from the modulation signal, and performs demodulation processing, error correction, and decoding processing on the modulation signal to reproduce the reproduction data. Is generated. The reproduction data is transferred to a host device (not shown) such as an audiovisual device or a personal computer.

The servo circuit 108 generates various servo drive signals for focus control and tracking control based on the servo control signals supplied from the matrix circuit 106, and uses these servo drive signals as the objective lens actuator of the optical pickup device 104. 209.

As shown in FIG. 2A, the objective lens actuator 209 includes a lens holder (movable part) 209L that holds the compatible objective lens 207, suspensions 209Sa and 209Sb that support the lens holder 209L, a magnetic circuit 209Ma, 209Mb. The objective lens actuator 209 further includes a focus coil and a tracking coil (not shown). The servo circuit 108 can shift the compatible objective lens 207 in the focus direction by supplying a servo drive signal (drive current) to the focus coil, and is compatible by supplying a servo drive signal (drive current) to the tracking coil. The objective lens 207 can be shifted in the radial direction.

1 can position the optical pickup device 104 by shifting the optical pickup device 104 in the radial direction of the optical disc 101 by the sled driving mechanism 105. Thereby, the optical pickup device 104 can irradiate a desired recording track of the optical disc 101 with a laser beam for reproduction or recording.

The operations of the servo circuit 108, laser control circuit 110, thread control circuit 111, and spindle control circuit 109 are controlled by the controller 112. The controller 112 is composed of a microcomputer and executes various control processes in accordance with commands from a host device (not shown).

FIG. 3 is a diagram schematically showing the optical path of the DVD / CD laser light in the optical pickup device 104. As shown in FIG. 3, the DVD / CD laser light La emitted from the optical integrated element 202 is incident on the optical surface 205b of the dichroic prism 205, passes through the dichroic prism 205, and is converted into parallel light by the collimator lens 206. Converted. The rising mirror 208 reflects this parallel light in the direction of the compatible objective lens 207. The compatible objective lens 207 condenses the light incident from the rising mirror 208 onto the optical disc 101 to form a condensing spot. On the other hand, the return light reflected by the optical disk 101 passes through the compatible objective lens 207 and is reflected by the rising mirror 208 in the direction of the collimator lens 206. Thereafter, the return light passes through the collimator lens 206 and the dichroic prism 205 in this order, and then is received by a light receiving element (not shown) of the optical integrated element 202.

FIG. 4 is a diagram schematically showing the optical path of the BD laser beam in the optical pickup device 104. As shown in FIG. 4, the BD laser light Lb emitted from the optical integrated element 202 is reflected by the reflection mirror 203 and enters the negative lens 204. The dichroic prism 205 reflects laser light incident on the optical surface 205 a from the negative lens 204 in the direction of the collimator lens 206. The rising mirror 208 reflects the parallel light emitted from the collimator lens 206 in the direction of the compatible objective lens 207. The compatible objective lens 207 condenses the light incident from the rising mirror 208 onto the optical disc 101 to form a condensing spot. On the other hand, the return light reflected by the optical disk 101 is transmitted through the compatible objective lens 207 and then reflected by the rising mirror 208 in the direction of the collimator lens 206. Thereafter, the return light enters the optical surface 205 c of the dichroic prism 205, is reflected inside the dichroic prism 205, and enters the negative lens 204. The reflection mirror 203 reflects the return light emitted from the negative lens 204 in the direction of the optical integrated element 201. A light receiving element (not shown) of the optical integrated element 201 receives the return light.

One of the features of the present embodiment is that an optical lens composed of a combination of a negative lens 204 and a collimator lens 206 is provided, in which a negative lens 204 having a negative refractive power is disposed in the optical path between the dichroic prism 205 and the reflecting mirror 203. The combined focal length of the system is larger than the focal length of the collimator lens 206 alone. Thereby, even if the focal length of the common collimator lens 206 is shortened, a long combined focal length can be secured. As will be described later, by increasing the combined focal length, the diameter of the focused spot when using the BD laser beam Lb can be reduced, and deterioration in reproduction performance can be suppressed. When the focal length of the collimator lens 206 is f ₁ and the focal length of the negative lens 204 is f ₂ , the combined focal length f _C of the optical system is given by the following formula (1).

In the above formula (1), d is an optical distance between the second principal point of the collimator lens 206 and the first principal point of the negative lens 204. For example, if d is 10 mm, fc = 32 mm, and f ₁ = 25 mm, the focal length f ₂ of the negative lens 204 is about −69 mm.

If the negative lens 204 is not provided, the condensing spot diameter of the BD laser light Lb on the optical disk 101 cannot be made sufficiently small, crosstalk between adjacent tracks on the optical disk 101 increases, and a short recording mark Therefore, it is difficult to ensure the desired reproduction performance. On the other hand, when the negative lens 204 is provided, the light transmittance of the optical system in the optical pickup device 104 decreases. However, since the laser output power increases year by year due to technological progress of the semiconductor laser element, the increase in the laser output power can compensate for the decrease in the light transmittance. For this reason, in the present embodiment, in order to ensure the reproduction performance, priority can be given to making the focused spot diameter sufficiently small.

The focused spot diameter is related to the rim light intensity, which is one of the standard evaluation conditions for optical discs. The rim light intensity refers to the ratio (= Ie / Imax) of the light intensity (= Ie) at the pupil edge to the maximum light intensity (= Imax) in the pupil of the objective lens. The rim light intensity is related to the beam divergence angle of the semiconductor laser element. An optical system (for example, a collimator lens 206 or a collimator lens) in which the beam divergence angle of laser light is θ (unit: °), the pupil diameter (diameter) of the compatible objective lens 207 is φ, and light is incident on the compatible objective lens 207. The rim light intensity I _RIM (unit: percent) is given by the following equation (2), where f is the focal length of the combination of 206 and the negative lens 204.

If the above equation (2) is arranged using the proportional coefficient K, the following equation (3) can be obtained.

5A to 5C are diagrams for explaining the beam divergence angle θ. The beam divergence angle θ has two types of values θv and θh. The beam divergence angle θh is a light intensity distribution in the _Xθ direction parallel to the light emitting end of the active layer, out of the light intensity distribution of the far field image (FFP) of the laser light Le emitted from the active layer of the semiconductor laser device 300. The full width at half maximum (the angular width when the light intensity I _X is 50% of the maximum value). The beam divergence angle θv is, of the light intensity distribution of the far-field pattern of the emitted laser light Le from the active layer of the semiconductor laser element 300 (FFP), the light in the vertical Y _theta direction to the light emitting end of the active layer It refers to the full width at half maximum of the intensity distribution (angle width when the light intensity I _Y is 50% of the maximum value).

Table 2 below shows the specifications of the beam divergence angles θh and θv of the laser light. Regarding the beam divergence angle θv, the value for BD is smaller than the value for DVD, and regarding the beam divergence angle θh, the value for BD is almost the same as the value for DVD.

Table 3 below shows the reference range of the rim light intensity for satisfying the reproduction performance.

As shown in Table 3, the minimum value (radial direction) of the rim light intensity is 55% in the case of BD, 60% in the case of DVD, and 50% in the case of CD. In order to obtain (reproduction performance in which the average symbol error rate is about 10 ⁻² or less), it is desirable to set the rim light intensity to be equal to or higher than these minimum values.

FIG. 6 is a graph showing the rim light intensity in the radial direction with respect to the focal length f of the optical system composed of the collimator lens 206 or the combination of the collimator lens 206 and the negative lens 204. As shown in the graph of FIG. 6, in order to set the rim light intensity beyond the minimum value (radial direction) of the rim light intensity shown in Table 3, a focal length of 32 mm or more is necessary in the case of BD. In the case of DVD, a focal length of 25 mm or more is necessary. With respect to CD, the minimum value (= 50%) of the rim light intensity is sufficiently achieved in the entire numerical range on the horizontal axis of the graph. Therefore, according to Table 3, the focal length f ₁ of the collimator lens 206 is a value of 25 mm or more in order to ensure the minimum value (= 60%) of the rim light intensity with respect to the DVD laser beam (oscillation wavelength: about 650 nm). It is desirable to be set to. The combined focal length f _C of the combination of the collimator lens 206 and the negative lens 204 is 32 mm in order to secure the minimum value (= 55%) of the rim light intensity with respect to the BD laser beam (oscillation wavelength: about 405 nm). It is desirable to set the above value. From the above, in order to satisfy the minimum value of the rim light intensity in all cases of BD, DVD, and CD, the combined focal length f _C may be set to 32 mm or more.

The optical pickup device 104 is required to reduce the outer shape in both the radial direction and the tangential direction. Since the focal length of the collimator lens 206 directly affects the outer dimension in the radial direction, the focal length is preferably as short as possible. Therefore, in order to reduce the outer dimension in the radial direction, the focal length f ₁ is set to 25 mm which minimizes the rim light intensity with respect to the DVD / CD laser beam, and the combined focal length f _C is set as the rim light with respect to the BD laser beam. It is preferable to set it to 32 mm which minimizes the strength. At this time, the focal length f ₂ of the negative lens 204 is about −69 mm according to the above equation (1).

When the negative lens 204 is not present, the focal length f ₁ of the collimator lens 206 is set to the minimum (= 60%) rim light intensity with respect to the DVD laser light in order to reduce the radial dimension of the optical pickup device 104. If it is set to 25 mm, as shown in FIG. 6, the rim light intensity with respect to the BD laser beam is significantly lower than the minimum value (= 55%) of the reference range. The desired reproduction performance cannot be ensured. In contrast, the optical pickup apparatus of this embodiment 104 has a negative lens 204, the value of the focal length f ₂ of the negative lens 204 is a rim light intensity for BD laser light to a minimum (= 55%) Therefore, it is possible to prevent the reproduction performance from being deteriorated when the BD laser beam is used.

As described above, according to the optical pickup device 104 of the first embodiment, even when the collimator lens 206 having a short focal length f ₁ is shared to reduce the size of the optical system, the negative lens 204 is not employed. As compared with, the focused spot diameter can be reduced by increasing the rim light intensity. Therefore, it is possible to prevent deterioration in reproduction performance when using the BD laser beam. Further, the adoption of the negative lens 204 makes the total length of the optical path of the BD laser light longer than that of the DVD / CD laser light, but the optical path of the BD laser light is bent by the reflection mirror 203. . Therefore, the optical integrated element 201 and the optical integrated element 202 can be disposed adjacent to each other, and the external dimensions of the optical pickup device 104 in the tangential direction can be reduced.

Further, as shown in FIG. 2, the optical axis (optical center axis) of the optical integrated element 201 and the optical axis (optical central axis) of the optical integrated element 202 are adjusted to be parallel to each other. Miniaturization of the optical pickup device 104 is realized.

There is an optical path difference between the optical path of the BD laser beam and the optical path of the DVD / CD laser beam. This optical path difference can be prevented from affecting the spherical aberration correction. For example, the spherical aberration due to the optical path of the DVD / CD laser light can be corrected by optimizing the lens characteristics of the optical system in the optical path. Further, spherical aberration that occurs when the optical disc 101 is a BD can be corrected using the collimator lens driving mechanism 210.

Embodiment 2. FIG.
Next, a second embodiment according to the present invention will be described. 7A and 7B are diagrams schematically showing the configuration of the optical pickup device 104B of the second embodiment. The configuration of the optical disk apparatus according to the present embodiment is the same as that of the optical disk apparatus 1 except that the optical pickup apparatus 104B shown in FIGS. 7A and 7B is provided instead of the optical pickup apparatus 104. .

FIG. 7A is a top view when the optical pickup device 104B is viewed from the normal direction perpendicular to the information recording surface of the optical disc 101 (Z-axis direction perpendicular to the X-axis and Y-axis). FIG. 7B is a schematic view when a part of the optical pickup device 104B is viewed from the side (X-axis direction). In FIGS. 7A and 7B and FIGS. 2A and 2B, components having the same reference numerals have the same functions, and thus detailed description thereof is omitted.

As shown in FIG. 7A, the optical pickup device 104B includes optical

integrated elements

201 and 202, a reflection mirror 203B, a negative lens (concave lens) 204B having negative refractive power, and a dichroic prism that is a beam splitter. 205B, a collimator lens 206, an objective lens actuator 209, and a collimator lens driving mechanism 210 are provided.

FIG. 8 is a diagram schematically showing an optical path of a DVD / CD laser beam in the optical pickup device 104B. As shown in FIG. 8, the DVD / CD laser beam La emitted from the optical integrated element 202 is incident on the optical surface 205Bc of the dichroic prism 205B, reflected inside the dichroic prism 205B, and then reflected by the collimator lens 206. Converted to parallel light. The rising mirror 208 reflects this parallel light in the direction of the compatible objective lens 207. The compatible objective lens 207 condenses the light incident from the rising mirror 208 onto the optical disc 101 to form a condensing spot. On the other hand, the return light reflected by the optical disk 101 passes through the compatible objective lens 207 and is reflected by the rising mirror 208 in the direction of the collimator lens 206. Thereafter, the return light passes through the collimator lens 206, enters the optical surface 205Bc of the dichroic prism 205B, is reflected inside the dichroic prism 205B, and then received by a light receiving element (not shown) of the optical integrated element 202. .

FIG. 9 is a diagram schematically showing an optical path of BD laser light in the optical pickup device 104B. As shown in FIG. 9, the BD laser light Lb emitted from the optical integrated element 201 is reflected by the reflection mirror 203B and enters the negative lens 204B. The dichroic prism 205B transmits laser light incident on the optical surface 205Ba from the negative lens 204B in the direction of the collimator lens 206. The rising mirror 208 reflects the parallel light emitted from the collimator lens 206 in the direction of the compatible objective lens 207. The compatible objective lens 207 condenses the light incident from the rising mirror 208 onto the optical disc 101 to form a condensing spot. On the other hand, the return light reflected by the optical disk 101 passes through the compatible objective lens 207 and is reflected by the rising mirror 208 in the direction of the collimator lens 206. Thereafter, the return light enters the optical surface 205Bc of the dichroic prism 205B and passes through the dichroic prism 205. Thereafter, the return light passes through the negative lens 204B and then enters the reflection mirror 203B. The reflection mirror 203B reflects the return light emitted from the negative lens 204B in the direction of the optical integrated element 201. A light receiving element (not shown) of the optical integrated element 201 receives the return light.

As described above, according to the optical pickup device 104B of the second embodiment, as in the case of the first embodiment, the collimator lens 206 having a short focal length f ₁ is shared in order to reduce the size of the optical system. However, compared to the case where the negative lens 204B is not employed, the rim light intensity can be increased and the focused spot diameter can be reduced. Therefore, it is possible to prevent deterioration in reproduction performance when using the BD laser beam. Further, the adoption of the negative lens 204B makes the total length of the optical path of the BD laser light longer than that of the DVD / CD laser light, but the optical path is bent by the reflection mirror 203B. Therefore, the optical integrated device 201 and the optical integrated device 202 can be disposed adjacent to each other, and the radial dimension of the optical pickup device 104B can be reduced.

Further, as shown in FIG. 7, since the optical axis of the optical integrated element 201 and the optical axis of the optical integrated element 202 are adjusted to be parallel to each other, this makes it possible to reduce the size of the optical pickup device 104B. The

Embodiment 3 FIG.
Next, a third embodiment which is a modification of the first embodiment will be described. FIGS. 10A and 10B are diagrams schematically showing the configuration of the optical pickup device 104C of the third embodiment. FIG. 10A is a top view when the optical pickup device 104C is viewed from a normal direction perpendicular to the information recording surface of the optical disc 101 (Z-axis direction perpendicular to the X-axis and Y-axis). FIG. 10B is a schematic view when a part of the optical pickup device 104C is viewed from the side (X-axis direction).

The difference between the optical pickup device 104C of the third embodiment and the optical pickup device 104 of the first embodiment is that the component 201 is relative to the straight line A1 that connects the center point of the turntable 102 and the optical axis center of the compatible objective lens 207. ˜206, 209, 210 are replaced with line symmetry. Therefore, the components of the optical pickup device 104C of the third embodiment and the components of the optical pickup device 104 of the first embodiment are arranged so as to be symmetrical with respect to the straight line A1. Therefore, also in the case of this embodiment, the same effect as in the case of Embodiment 1 can be obtained.

Embodiment 4 FIG.
Next, a fourth embodiment which is a modification of the second embodiment will be described. FIGS. 11A and 11B are diagrams schematically showing a configuration of the optical pickup device 104D of the fourth embodiment. FIG. 11A is a top view when the optical pickup device 104D is viewed from the normal direction perpendicular to the information recording surface of the optical disc 101 (Z-axis direction perpendicular to the X-axis and Y-axis). FIG. 11B is a schematic cross-sectional view of the optical pickup device 104D as viewed from the side (X-axis direction).

The difference between the optical pickup device 104D of the fourth embodiment and the optical pickup device 104B of the second embodiment is that the component 201 is relative to a straight line A2 connecting the center point of the turntable 102 and the optical axis center of the compatible objective lens 207. , 202, 203B, 204B, 205B, 206, 209, and 210 are replaced with line symmetry. Therefore, the components of the optical pickup device 104D according to the fourth embodiment and the components of the optical pickup device 104B according to the second embodiment are arranged so as to be symmetrical with respect to the straight line A2. Therefore, also in the case of the present embodiment, the same effect as in the case of the second embodiment can be obtained.

As described above, the embodiments of the present invention have been described with reference to the drawings. However, these are exemplifications of the present invention, and various configurations other than the above can be adopted. For example, in the first to fourth embodiments, the

optical pickup devices

104 and 104B to 104D have the optical

integrated elements

201 and 202 that emit three types of laser beams having different oscillation wavelengths. Is not limited to three types.

1 optical disk device, 101 optical disk, 102 turntable, 103 spindle motor, 104 optical pickup device, 105 thread drive mechanism, 106 matrix circuit, 107 signal reproduction circuit, 108 servo circuit, 109 spindle control circuit, 110 laser control circuit, 111 thread Control circuit, 112 controller, 201, 202 integrated optical element, 203, 203B reflecting mirror, 204, 204B negative lens, 205, 205B dichroic prism (beam splitter), 206 collimator lens, 207 compatible objective lens, 208 reflecting mirror (start up) Mirror), 209 objective lens actuator, 210 collimator lens drive mechanism.

Claims

A first integrated optical element including a first laser light source that emits laser light having a first oscillation wavelength and a first light receiving element;
A second optical integrated element including a second laser light source that emits a laser beam having a second oscillation wavelength longer than the first oscillation wavelength, and a second light receiving element;
The first oscillation surface having a first optical surface, a second optical surface, and a third optical surface, which is incident on the first optical surface from the first optical integrated element through the first optical path. The laser light is guided and emitted from the third optical surface, and the laser light having the second oscillation wavelength incident on the second optical surface from the second optical integrated element through the second optical path is emitted. A beam splitter that guides the light from the third optical surface;
The laser beam having the first oscillation wavelength emitted from the third optical surface of the beam splitter is converted into first parallel light, and the laser having the second oscillation wavelength emitted from the third optical surface. A parallel optical system for converting light into second parallel light;
A condensing optical system for condensing the first parallel light emitted from the parallel optical system onto the optical disc and condensing the second parallel light emitted from the parallel optical system onto the optical disc;
A negative lens having a negative refractive power disposed in the first optical path and diverging the laser light having the first oscillation wavelength emitted from the first optical integrated element;
A total reflection mirror disposed in the first optical path and configured to reflect the laser light having the first oscillation wavelength emitted from the first optical integrated element toward the first optical surface;
The return light reflected by the optical disc enters the third optical surface of the beam splitter through the condensing optical system and the parallel optical system,
The beam splitter guides the laser light having the first oscillation wavelength in the return light and emits the laser light from the first optical surface, and guides the laser light having the second oscillation wavelength in the return light. Emanating from the second optical surface,
The first optical integrated element receives the laser light having the first oscillation wavelength that is emitted from the first optical surface and is incident through the negative lens and the total reflection mirror,
The second optical integrated element receives the laser light having the second oscillation wavelength emitted from the second optical surface;
The focal length of the parallel optical system is set to a value that minimizes the rim light intensity with respect to the laser light having the second oscillation wavelength within the first predetermined range,
The focal length of the negative lens is set to a value that minimizes the rim light intensity with respect to the laser light having the first oscillation wavelength within a second predetermined range,
The first optical integrated element is disposed at an end of the first optical path bent by the total reflection mirror, and is disposed adjacent to the second optical integrated element. Pickup device.
2. The optical pickup device according to claim 1, wherein an optical axis of the first optical integrated element and an optical axis of the second optical integrated element are parallel to each other.
3. The optical pickup device according to claim 1, wherein the rim light intensity with respect to the laser light having the second oscillation wavelength is I RIM, and the focal length of the parallel optical system that makes light incident on the condensing optical system is where f is the beam spread angle of the second laser light source is θ (unit: °), the pupil diameter of the condensing optical system is φ, and the proportionality coefficient is K, the focal length f of the parallel optical system Is the following formula:

An optical pickup device provided according to claim 1.
The optical pickup device according to any one of claims 1 to 3,
The minimum value in the first predetermined range is 55%;
An optical pickup device characterized in that the minimum value in the second predetermined range is 60%.
The optical pickup device according to any one of claims 1 to 4,
The first oscillation wavelength is 405 nm,
The second oscillation wavelength is 650 nm.
An optical pickup device characterized by that.
The optical pickup device according to any one of claims 1 to 5,
The condensing optical system includes an objective lens shared for the laser light of the first oscillation wavelength and the laser light of the second oscillation wavelength,
The objective lens has a first numerical aperture for the laser light having the first oscillation wavelength and a second numerical aperture smaller than the first numerical aperture for the laser light having the second oscillation wavelength. An optical pickup device having a numerical aperture.
7. The optical pickup device according to claim 1, wherein the beam splitter transmits laser light having the first oscillation wavelength incident on the first optical surface to the parallel optical system. An optical pickup device that transmits laser light having the second oscillation wavelength that is reflected in a direction and incident on the second optical surface.
7. The optical pickup device according to claim 1, wherein the beam splitter transmits laser light having the second oscillation wavelength incident on the second optical surface to the parallel optical system. An optical pickup device that transmits laser light having the first oscillation wavelength that is reflected in a direction and incident on the first optical surface.
An optical disc device comprising the optical pickup device according to any one of claims 1 to 8.
10. The optical disc apparatus according to claim 9, wherein recording information of the optical disc is recorded based on a detection signal output from either one of the first light receiving element and the second light receiving element of the optical pickup device. An optical disc apparatus further comprising a signal reproduction circuit for reproduction.