JP2003308626A - Optical pickup device and optical disk drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pickup device, in which a conductive leaf spring member is arranged between an optical base and a laser element, and an optical disk drive using this optical pickup device. <P>SOLUTION: This device is provided with at least one or more laser elements 50 (1st light source units) for irradiating an information recording surface of the optical disk with laser beams, the optical base 60 consisting of a conductive material to form an optical path for guiding the laser beams emitted from the laser elements which are formed at specified positions, to an objective lens, and the conductive leaf spring member 70 for electrically jointing the laser elements 50 and the optical base 60. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head device used for recording information on a recording medium using a light beam and reading already recorded information from the recording medium, and an optical head of this kind. The present invention relates to an optical disk device using the device.

[0002]

2. Description of the Related Art As is well known, in recent years, in the field of recording media, high density recording has been achieved even though it is as large as the diameter (12 cm) of a conventional CD (Compact Disk) for recording audio and digital data. Possible DVD (Digital
Versatile Disk) has been developed. Since the DVD has a high recording density, a beam having a wavelength (650 nm) shorter than the wavelength (780 nm) of the light for reading the CD data is required.

As an optical disk device, a disk system capable of recording and reproducing both a disk system of CD and a DVD is desired. As a result, as an optical pickup device using a light emitting element (laser element) that emits a light beam (laser beam) of a predetermined wavelength, a first light source for DVD (wavelength 650 nm) and a second light source for CD are used. Light source (wavelength 7
80 nm) has been developed. Thus, the optical pickup device has the first light source (for DVD) and the second light source (for CD).

The laser light emitted from the first light source passes through the hologram and enters a dichroic PBS (Polarized Beam Splitter) capable of photosynthesis and light splitting. The laser light transmitted through this dichroic PBS is
The collimator light passes through the collimator lens, becomes collimator light, and enters the objective lens. The light condensed by the objective lens is applied to the recording surface of the disc.

The light reflected from the disk passes through the objective lens, the collimator lens and the dichroic PBS and enters the hologram. A hologram diffracts reflected light and guides it to a photodetector using a photodiode. The photodetector outputs a focusing error signal, a tracking error signal and a read signal.

The laser light emitted from the second light source enters the dichroic PBS. The light beam reflected and emitted inside the dichroic PBS passes through the collimator lens, becomes collimator light, and enters the objective lens. The light condensed by the objective lens is applied to the recording surface of the disc.

The light reflected from the disk passes through the objective lens, the collimator lens and the dichroic PBS and enters the hologram. The reflected light diffracted by the hologram is guided to the photodetector using a photodiode.

[0008]

The above optical pickup device is composed of an actuator for driving an objective lens, a dichroic PBS, an optical base for holding optical components such as a collimator lens and a laser element at predetermined positions. The optical component needs to be accurately arranged at a predetermined position. This also applies to the laser device. When the position of the laser element is displaced, the characteristics of the optical pickup deteriorate due to the deterioration of the optical performance such as the deterioration of the wavefront aberration, and there is a problem that a reading error of the optical disk occurs or a writing error occurs during writing. Occurs.

On the other hand, in the case where the position of the laser element is adjusted and fixed in this way, it is often the case that the optical base side is provided with play in order to secure the adjustment range. Alternatively, there is a configuration in which the laser element is adhered and fixed to the optical base with an adhesive in order to hold the laser element at a predetermined position.

The laser device is usually a GN of a laser chip.
The D terminal portion is soldered to a part of the laser element housing made of a conductive metal member, so that the conductivity and the heat dissipation are secured. In the laser device having such a structure,
The laser element potential fluctuates due to the oscillation of the laser light,
When the laser element housing is in close contact with the conductive optical base, there is no problem because the optical base has a stable GND. However, as described above, when the looseness between the optical base and the laser element housing or the adhesive for adhering and fixing the both goes into between the optical base and the laser element housing, the laser element housing is It may be electrically separated from the optical base. In such a case, the GND potential fluctuates due to the laser oscillation, and the potential of the signal system also fluctuates, which significantly deteriorates the signal quality. In particular, since a writing-type optical disk device uses a large output laser power, the influence on the GND potential becomes large, which is likely to cause a problem.

An object of the present invention is to solve such a problem, and an object thereof is to realize an optical pickup device and an optical disk device in which a conductive leaf spring member is arranged between an optical base and a laser element.

[0012]

In order to achieve the above-mentioned object, the present invention forms at least one laser element for irradiating the information recording surface of a disk with a laser beam and the laser element at a predetermined position. Then, an optical base made of a conductive material that forms an optical path for guiding the laser light emitted from the laser element to the objective lens, and a conductive member that electrically bonds the laser element and the optical base to each other. And is provided.

With the above structure, the conductive leaf spring member for joining the laser element and the optical base made of a conductive material to each other is provided, so that the adhesive enters between the laser element and the optical base. Even in such a case, it is possible to perform electrical connection, the GND potential does not fluctuate due to the high-power laser element, and stable signal transmission can be performed.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 (a), (b)
2A and 2B are conceptual diagrams of the optical pickup device described in this embodiment, FIG. 1A is a plan view, and FIG. 1B is a side view. Hereinafter, description will be given with reference to both these drawings.

That is, the first light source unit 201 is attached to one side wall 102 of the optical base 101. This first light source unit 201 has a wavelength of 650
It is a light source (first light source) for DVD that emits a laser beam of nm.

Then, in the first light source unit 201, the reflected light from the disk 400 is reflected by the hologram 301.
There is provided a photodetector 20 which is diffracted and irradiated by and is photoelectrically converted to obtain a reproduction signal, a focusing error signal and a tracking error signal.

The other side wall 10 of the optical base 101 is also provided.
A second light source unit 202 is attached to 3. This second light source unit 202 has a wavelength of 780 nm.
Is a light source (second light source) for the CD that emits the laser light.

As described above, the optical pickup device includes the first
Light source (for DVD) and a second light source (for CD). The laser light emitted from the first light source unit 201 is projected on the plane 104 of the optical base 101.
4 is emitted in a direction substantially parallel to 4 and enters the dichroic PBS 302 via the hologram 301.

The laser light from the first light source unit 201 goes straight through the dichroic PBS 302, then passes through the collimator lens 303, and then the reflection mirror (prism) 30.
It is incident on 6.

The light reflected by the reflection mirror 306 is
Objective lens 307 arranged above reflection mirror 306
Incident on. The light focused by the objective lens 307 is
The reflection layer (information recording surface) of the optical disc 400 located above the objective lens 307 is irradiated with the light.

The light reflected by the information recording surface of the optical disc 400 enters the dichroic PBS 302 via the objective lens 307 and the reflection mirror 306. The reflected light that has entered the dichroic PBS 302 travels straight, is diffracted by the hologram 301, enters the photodetector 20 in the first light source unit 201, and generates the playback signal, focusing error signal, and tracking error signal described above. Be used for.

The laser light emitted from the second light source unit 202 is radiated on the plane 104 of the optical base 101 in a direction substantially parallel to the plane 104, and is incident on the dichroic PBS 302 via the hologram 311. .

The laser light from the second light source unit 202 is reflected inside the dichroic PBS 302 to change its direction, and enters the collimator lens 303. The laser light incident on the collimator lens 303 enters a reflecting mirror (prism) 306.

The light reflected by the reflection mirror 306 is
Objective lens 307 arranged above reflection mirror 306
Incident on. The light focused by the objective lens 307 is
The reflection layer (information recording surface) of the optical disc 400 located above the objective lens 307 is irradiated with the light.

The light reflected by the information recording surface of the optical disc 400 enters the dichroic PBS 302 via the objective lens 307 and the reflection mirror 306. The reflected light incident on the dichroic PBS 302 is reflected, diffracted by the hologram 311 and incident on the photodetector 21 in the second light source unit 202 to generate the reproduction signal, the focusing error signal and the tracking error signal described above. Be used for.

The objective lens 307 is held by a lens holder (not shown). The lens holder is
It is supported by one end of a plurality of wires, and fine movement control is possible in the focus direction and the tracking direction. The plurality of wires is held by a wire holder attached to the optical base 101.

Further, for example, a small focusing control permanent magnet and a small tracking control permanent magnet are attached to the lens holder. Focusing control yoke coils and tracking control yoke coils are arranged on the optical base in the vicinity of these permanent magnets. Then, by supplying the focusing control signal and the tracking control signal to the focusing control yoke coil and the tracking control yoke coil, respectively, the objective lens 307 can be finely controlled in the focus control direction and the tracking control direction, respectively. .

Next, the structure of an optical disk device using the above-mentioned optical pickup device will be described. In FIG. 2, D
T is a disc table that holds the optical disc 400 as a storage medium. This disc table DT
Are rotationally driven by a disk motor controlled by a servo circuit.

Reference numeral 100 is an optical pickup device,
As described with reference to FIG. 1, the information recording surface of the optical disc 400 held on the disc table DT and rotated at a predetermined speed is irradiated with a laser beam, and the optical disc 4 is rotated.
The reflected laser beam reflected by the information recording surface of No. 00 is taken in, and the electric signal corresponding to the light intensity of the reflected laser beam is output.

The optical pickup device 100 is arranged along a guide rail 600 provided in a predetermined positional relationship with the disc table DT, in a direction orthogonal to the tangential direction of the track formed on the information recording surface of the optical disc 400 (optical disc). It is movable in the radial direction of 400, that is, the tracking control direction. The optical pickup device 100 is
The linear motor reciprocates on the guide rail 600.

The output signal of the photodetector 20, which is built in the first light source unit 201 of the optical pickup device 100 and receives the reflected light from the optical disk 400, outputs a signal processing circuit 701, a tracking control circuit 702, and a focusing control circuit 703. Be led to. The signal processing circuit 701 is
The arithmetic processing for reproducing the information recorded on the optical disc 400 is executed.

The tracking control circuit 702 also processes the signal obtained from the optical disk 400 to generate a tracking error signal, and generates a tracking control signal to be supplied to the tracking control yoke coil. The focusing control circuit 703 controls the optical disk 4
The signal obtained from 00 is arithmetically processed to generate a focusing error signal, and a focusing control signal to be supplied to the focusing control yoke coil is generated.

The laser drive circuit 705 is an AP (not shown).
The power of the laser light of the first light source unit 201 and the second light source unit 202 is controlled according to a control signal from a C (automatic power control) circuit. The APC circuit determines whether the input detection signal is a signal of a preset level and supplies the control signal obtained based on the determination result to the laser drive circuit 705. . As a result, the power of the output laser light or the light amount of the reflected light from the optical disc 400 is automatically controlled so as to be within the preset standard range.

The first and second light source units 201,
In 202, laser elements each emitting a light beam (laser beam) of a predetermined wavelength are used. In addition, the objective lens 307 is, by the lens holder, a direction orthogonal to the tangential direction of the track (radial direction of the optical disc 400) and a laser beam passing direction (optical disc 4).
00 in a direction orthogonal to the information recording surface).

The radial direction of the optical disk 400 is called the tracking control direction. The direction orthogonal to the information recording surface of the optical disc 400 is called the focusing control direction. The tracking control circuit 702 generates a tracking control signal from the tracking error signal and supplies it to the tracking control yoke coil. Further, the focusing control circuit 703 generates a focusing control signal from the focusing error signal and supplies it to the focusing control yoke coil.

The system control unit 710 controls the operation timing of the entire circuit and switching control of operation conditions (parameters, etc.).
It is set by the control signal from. Further, this optical disk device is a ROM (Read Onl) that stores a program read when the power supply device and the device itself are operated.
y Memory), a RAM [Random A that temporarily stores data read from the optical disc 400 or data input from a host computer, control data, and the like.
ccess Memory] is provided.

In the above description, the operation at the time of reproducing information from the optical disk 400 has been described, but it goes without saying that the apparatus of the present invention can be applied to information recording on a RAM disk. At this time, the laser drive circuit 705 is modulation-controlled according to the recording information, and
The average power of the laser light is controlled by the APC circuit so as to reach the recording level.

Next, FIG. 3 shows the arrangement structure of the laser element and the optical base in the above-mentioned optical pickup device.
And FIG. 4 will be described. FIG. 3 is a perspective view of the optical pickup device, and FIG. 4 shows a connection state of a leaf spring member connected to the optical base and the laser element, as viewed from the X ′ direction in FIG.

Reference numeral 50 denotes a laser element, which constitutes a part of the first light source unit 201 as described with reference to FIG. 1. This laser element 50 is a laser chip or a light for actually irradiating laser light. It has a detector 20. The photodetector 20 converts the received reflected light into an electric signal, and the signal processing circuit 701 and the tracking control circuit 7 through the terminal 52 protruding from the laser element 50 in the X direction in the drawing.
02 and the focus control circuit 703. The terminal 52 is actually soldered to a flexible cable (not shown) to supply an electric signal. Further, a resinous spacer 51 is arranged on one end face of the laser element 50 in the X direction in the drawing so as to penetrate the terminal 52.

Reference numeral 60 denotes an optical base made of a conductive material. The optical base 60 has the laser element 50, the dichroic PBS 302, and the collimator lens 30.
3, optical components such as the laser element 50 are provided at predetermined positions. The laser element 50 is the YY of the laser element 50.
The optical base 60 is in contact with the side surface in the direction 'and fixedly adhered thereto via an adhesive.

Reference numeral 70 denotes a conductive leaf spring member made of, for example, metal and is arranged so as to cover a part of the upper surface of the optical base 60 in the figure. Although not actually visible in FIG. 3, the leaf spring member 70 is also arranged on the lower surface of the optical base 60 in the figure. Here, the leaf spring member 70 arranged on the upper surface of the optical base 60 has a first protrusion 53 and a second protrusion 54, and the first protrusion 53 and the second protrusion 54 are About 90 with respect to the upper surface of the optical base 60
It is bent every time. The bent first projecting portion 53 and second projecting portion 54 are provided with holes 57 and 58 for penetrating the projecting portions 55 and 56 projecting in the X direction from the one end surface of the optical base 60. It is in contact with the parts 55 and 56. That is, the optical base 60 and the leaf spring member 7
0 is in a state of being surely contacted via the projections 55 and 56. Further, the first protrusion 53 and the second protrusion 54 are formed such that the tip shapes thereof are wide, and the wide portions are in contact with one end surface of the laser element 50.

Specifically, referring to FIG. 4, the first projecting portion 53 and the second projecting portion 54 are bent at the portion indicated by the alternate long and short dash line in the figure, and the bent portion and the laser element 50 are in contact with each other. is doing.

Therefore, by using such a conductive metal leaf spring member 70, the position of the laser element 50 can be adjusted, and even if the position is adjusted, the optical base 60 and the laser element 50 can be displaced. The same potential is held between 50 by the metal leaf spring member 70.

Further, by devising the strength or shape of the leaf spring in order to stabilize the contact between the two, it is possible to further improve the reliability. In the illustrated example, the shape of the tip of the leaf spring is wide so that the contact between the laser element housing and the leaf spring is always maintained even if the attitude of the laser element changes. Further, in order to enhance the reliability of contact, it is possible to make the contact portion uneven.

Further, instead of the metal leaf spring member 70,
It is also possible to electrically connect the optical base 60 and the laser element 50 by applying a conductive gel-like paste between them. By using this gel-like paste, it is possible to cope with a complicated external shape.

According to the above-described embodiment, the GND portion of the laser element 50 and the optical base 60 are bonded by the conductive member in this manner, so that the GND potential is kept stable even during laser oscillation and the signal quality is improved. Also improves.

Furthermore, recently, along with the weight reduction of the optical disc apparatus, the weight of the optical pickup apparatus 100 is also reduced, and it can be seen that a plastic material is used as the optical base 60. Plastic materials generally have poor conductivity. In this case, it becomes difficult to maintain the same electric potential between the laser element 50 and the optical base 60 as described above. In such a case, the same effect can be obtained by joining a part of the flexible cable used for signal transmission and the laser element 50 and connecting them to the GND terminal of the optical disk device.

The present invention is not limited to the above-described embodiment, and can be variously modified in an implementation stage without departing from the scope of the invention.

[0049]

As described above, in the optical pickup device, by disposing the conductive leaf spring member so as to contact the optical base and the laser element, the GND potential may be changed by the high-power laser element. As a result, stable signal transmission can be performed.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of an optical pickup device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of an optical disc device using an optical pickup device.

FIG. 3 is a perspective view of an optical pickup device.

FIG. 4 is a diagram showing a connection state of a leaf spring member connected to an optical base and a laser element.

[Explanation of symbols]

20, 21 Photodetector 50 laser device 51 spacer 52 terminals 53 First protrusion 54 Second protrusion 55, 56 Projection 57, 58 holes 60 optical base 70 leaf spring member 201 First light source unit 202 Second light source unit 301, 311 hologram 302 Dichroic PBS 303 Collimator lens 306 reflective mirror 307 Objective lens 400 optical disc

Claims (6)

[Claims] 1. At least one laser element for irradiating a laser beam on an information recording surface of a disc, the laser element is formed at a predetermined position, and the laser beam emitted from the laser element is guided to an objective lens. An optical pickup device comprising: an optical base made of a conductive material for forming an optical path for forming the optical path, and a conductive member for electrically connecting the laser element and the optical base to each other. 2. The optical pickup device according to claim 1, wherein the conductive member is formed in a concavo-convex shape at a joint portion between the laser element and the optical base. 3. The optical pickup device according to claim 1, wherein the conductive member is a conductive gel-like member. 4. At least one laser element for irradiating a laser beam on an information recording surface of a disc, the laser element is formed at a predetermined position, and the laser beam emitted from the laser element is guided to an objective lens. And an optical base made of a conductive material for forming an optical path, a conductive member for electrically bonding the laser element and the optical base to each other, and a photodetector for detecting the laser light reflected from the disk. And an optical disk device, characterized in that the objective lens is driven based on the laser light detected by the photodetector. 5. The optical disk device according to claim 4, wherein the conductive member is formed in a concavo-convex shape at a joint portion between the laser element and the optical base. 6. The optical disk device according to claim 4, wherein the conductive member is a conductive gel member.