JP2003272197A - Optical pickup device and optical information processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a bump of objective lenses or lens holders against optical disks when another objective lens is accessing to its corresponding optical disk in an optical pickup device which has a plurality of objective lenses having largely different operation distances. <P>SOLUTION: The device has a plurality of focusing means F1 and F2 and a dislocating mechanism which varies the relative distances of one or more focusing means and the optical disks, and the bump of other objective lenses or lens holders against the optical disks is prevented when an objective lens is accessing to its corresponding optical disk. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device and an optical information processing device.

[0002]

2. Description of the Related Art As an optical disc, a DVD having a higher recording density in addition to a conventional CD (compact disc)
(Digital Video Disc) has been put into practical use, and it is intended to realize an optical disc having a high recording density of the next generation, which further increases the recording density.

When a next-generation optical disk with an increased storage capacity appears, the "drive device" for recording / reproducing the optical disk is the DVD which is the optical disk used up to now.
It is preferable to be able to record / play back even on CDs,
When a next-generation optical disk of DVD comes out, it is considered that the drive device thereof is required to have a drive function for DVD and CD.

An orthodox method for realizing a high recording density is to reduce the spot diameter of an optical spot for recording / reproducing on an optical disc. To make the spot diameter smaller, a method of shortening the recording wavelength, a method of increasing the numerical aperture (hereinafter referred to as NA) of the objective lens for condensing the light spot, or a method of shortening the recording wavelength and increasing NA are used. A method can be considered.

Generally, the NA of an objective lens is proportional to the effective radius: r of the objective lens and inversely proportional to the focal length: f.
Therefore, when the NA of the objective lens is increased, if the lens diameter is considered to be constant, the focal length f becomes short, and as a result, the working distance between the optical disc and the objective lens (Workin
Below g Distance, it is called WD. ) Becomes shorter.

Next-generation optical discs with even higher recording density have appeared, and in the case of recording / reproducing on the same drive device as conventional CDs and DVDs, it is conceivable that conventional optical discs (CDs, DVDs) will be used. ) Corresponding to a conventional objective lens and a high NA objective lens for high recording density,
Although a conventional objective lens is used to access a conventional optical disc, and a high NA objective lens is used to access a high recording density optical disc, a high NA objective lens has a short WD, and When an optical disc is being accessed, there is a possibility that the objective lens having a high NA may collide with the conventional optical disc only by being present there.

[0007]

In an optical pickup device having a plurality of objective lenses having large working distances (for example, 0.5 mm or more) different from each other, when the corresponding optical disc is accessed by a certain objective lens, another objective lens or An object of the present invention is to realize a highly reliable optical pickup device that avoids the lens holder from colliding with the optical disc and does not damage the optical disc or the objective lens.

Another object is to realize a highly reliable optical information processing device (drive device) which does not damage the optical disc or the objective lens.

[0009]

An optical pickup device according to claim 1 is an "optical pickup device having a plurality of focusing means and a displacement mechanism for changing a relative distance between one or more focusing means and an optical disk". is there.

An optical pickup device according to a second aspect of the invention has first and second focusing means. The "first focusing means" has a first objective lens and a first focusing mechanism. The "first focusing mechanism" is a mechanism for keeping the distance between the first objective lens and the first optical disc constant. The "first optical disc" is one accessible using the first objective lens.
There are more than one optical disc.

The "second focusing means" has a second objective lens and a second focusing mechanism.
The "second focusing mechanism" is a mechanism for keeping the distance between the second objective lens and the second optical disk constant. A "second optical disc" is one or more types of optical discs accessible using a second objective lens.

The retracting range of the second focusing mechanism is larger than the retracting range of the first focusing mechanism.
When the objective lens of is accessing the second optical disc,
The first objective lens or the first focusing means is arranged at "a position where it does not come into contact with the second optical disc".

An optical pickup device according to a second aspect of the present invention can be configured such that "the distance between the first objective lens and the optical disc is equal to the distance between the second objective lens and the optical disc" in a natural state (claim). Item 3). "Natural state" is
It is in a state where the driving force by the focusing mechanism is not received.

In the optical pick-up device according to the second or third aspect, in order to change the relative distance between the first objective lens and the optical disk, "a coarse movement displacement mechanism for performing coarse movement displacement of the first objective lens in the focusing direction. , And a fine displacement mechanism for finely displacing for the purpose of focusing (claim 4).

An optical information processing apparatus according to a fifth aspect uses the optical pickup apparatus according to any one of the second to fourth aspects, and performs at least one of recording / reproducing / erasing information on / from a plurality of types of optical disks. It is characterized by performing.

An optical information processing device according to a sixth aspect is an optical information processing device for performing one or more of information recording / reproducing / erasing on / from a plurality of types of optical discs by using the optical pickup according to the first aspect. As a displacement mechanism for changing the relative distance between one or more focusing means and the optical disc, a mechanism for changing the relative distance between the entire optical pickup and the optical disc holding mechanism in the focusing direction is characterized.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of an optical pickup device. Only the basic optical arrangements are shown schematically to avoid complication of the figures. Various conventionally known optical arrangements can be appropriately used.

In the figure, reference numerals D1 and D2 denote the first
And a second optical disc is shown. The “first focusing means” indicated by reference numeral F1 is the first objective lens O.
L1 and “a first focusing mechanism (not shown) for keeping the distance between the first objective lens OL1 and the first optical disc D1 constant”.

The "second focusing means" indicated by the symbol F2 is a second focusing mechanism (which keeps the distance between the second objective lens OL2 and the second optical disc D2 constant). (Not shown) ”.

As the first and second focusing mechanisms, any conventionally known one can be used. The WD of the second objective lens OL2 is larger than the WD of the first objective lens OL1, and accordingly, the retracting range of the second focusing mechanism used in the second focusing means F2 is the first range. Is larger than the retractable range of the first focusing mechanism used in the focusing means F1.

The focusing means refers to the whole of the objective lens, the focusing mechanism, the lens barrel, and the casing that houses them.

When accessing the first optical disk D1 (either recording, reproducing or erasing), the semiconductor laser OR1 is driven. The emitted light beam is collimated into a parallel light beam by the collimator lens C1, and the polarized beam splitter PBS is used.
The light is reflected by the objective lens OL1 side by 1 and passes through the quarter-wave plate WP1 and is condensed as a light spot on the recording surface of the first optical disc D1 by the objective lens OL1.

The light reflected by the recording surface becomes a return light beam, passes through the objective lens OL1, returns to the polarization beam splitter PBS1 via the quarter wavelength plate WP1, passes through this, and passes through the detection lens L1 to the photodetector element PD1. Upon incidence, various signals (RF signal, focusing signal, tracking signal) are generated.

When accessing the second optical disk D2 (either recording, reproducing or erasing), the semiconductor laser OR2 is driven. The radiated light flux passes through the polarization hologram H2, and is focused as a light spot on the recording surface of the second optical disc D2 by the objective lens OL2 via the quarter wavelength plate WP2.

The light reflected by the recording surface becomes a return light beam, passes through the objective lens OL2, is diffracted by the polarization hologram H2 via the quarter wavelength plate WP2, and is detected by the photodetector element PD2.
To generate various signals similar to the above.

In FIG. 1A, reference numeral 10 indicates a housing of the optical pickup device.

As shown in FIG. 1B, in the natural state,
The distance between the first objective lens OL1 and the optical disc D1 is substantially equal to the distance between the second objective lens OL2 and the optical disc D2 (claim 3). When accessing the optical disc D2, focusing control of the objective lens OL2 is performed by the second focusing mechanism in the state of FIG. 1B. Although the WD of the objective lens OL2 is large and the retracting range of the second focusing mechanism is large, at this time, the first focusing means F1 including the first objective lens OL1 is located at a position sufficiently away from the optical disc D2 (second Since it is arranged at a position where it does not come into contact with the optical disc (claim 2), the first focusing means F1 does not collide with the optical disc D2.

When accessing the first optical disk D1, as shown in FIG. 1 (c), the first focusing means F1 is moved by a known appropriate displacement means (not shown).
Is displaced in the focusing direction so that the optical disc D1
And the focusing control is enabled by the WD of the objective lens OL1. Then, access is performed in this state.

FIG. 2 shows a modification of the above embodiment. In the natural state, the distance between the first objective lens OL1 and the optical disc D1 is substantially equal to the distance between the second objective lens OL2 and the optical disc D2 (claim 3). A coarse movement displacement mechanism (composed of an actuator AC and a coarse movement signal generation circuit KS) for coarsely displacing the objective lens OL1 in the focusing direction in order to change the relative distance between the first objective lens OL1 and the optical disc D1. , And a fine movement displacement mechanism (composed of an actuator AC and a fine movement signal generation circuit KB) for performing fine movement displacement for focusing (claim 4).

When the second objective lens OL2 having a wide pull-in range accesses the second optical disk D2 or in the standby state, the first objective lens OL1 having a narrow pull-in range is the second objective lens OL1.
It is located at substantially the same position (in the focusing direction) as the objective lens OL2. Only when the optical disk D1 to be supported by the first objective lens having a narrow pull-in range is inserted, a predetermined current is passed from the coarse movement signal generation circuit KS to the focusing coil of the actuator AC, and a predetermined amount (0.5 to 1 mm) is applied to the optical disk D1. Objective lens OL1 to approach
Is displaced, and the magnetic circuit of the actuator AC is designed so that the position of the objective lens OL1 at that time becomes the “nominal position when accessing the first optical disc D1”, and the first optical disc D1 is centered around that position. The fine focusing is performed by the fine movement signal (focusing signal) from the fine movement signal generation circuit KB.

FIG. 3 shows another embodiment of the optical pickup device. In this form, there is a step on the upper surface of the upper casing UK of the optical pickup device, and the step is smoothly connected. First focusing means F
When the first optical disc is accessed, the first and second focusing means F2 are both located at the "top of the step" as shown in FIG. 3 (a). At this time,
The position where the first focusing means F1 is located is the access position. Therefore, the access to the first optical disc is executed in the state of FIG.

When accessing the second optical disk,
The first and second focusing means F1, F2 are shown in FIG.
By displacing as shown in (b), the first focusing means F1 is moved to the lower part of the step and retracted from the second optical disc. Then, the second focusing means F2 is positioned at the access position. Objective lens OL in this state
Access by 2.

FIG. 4 shows another form of the optical pickup device. In this embodiment, the first objective lens O
L1 and its focusing means (first focusing means (not shown)), second objective lens OL2 and its focusing means (second focusing means (not shown)) are unitized as a displacement unit UT,
By using an appropriate displacement mechanism M that uses a cam, gear, etc., the "focusing direction in the displacement unit UT (up and down direction in the figure)
Can be displaced. "

As shown in FIG. 4 (a), when accessing the second optical disc D2, the displacement unit UT adjusts the optical disc D to the WD of the second objective lens OL2.
Distance from 2. At this time, the first objective lens O
Since L1 is arranged sufficiently away from the optical disc D2,
The retracting operation of the objective lens OL2 does not collide with the optical disc D2.

When the first optical disc D1 is accessed, the displacement unit UT is displaced toward the first optical disc D1 by the displacement mechanism M, and the first objective lens O
The distance from the optical disc D1 is set according to the WD of L1. In this state, the optical disc D1 is accessed.

Each of the optical pickup devices described with reference to FIGS. 1, 3 and 4 has a plurality of focusing means and one or more focusing means and the optical disks D1 and D.
It has a displacement mechanism that changes the relative distance between the first and second electrodes (claim 1).

In each of the embodiments described above, before the optical disc is inserted, the first focusing means F1 for mounting the objective lens (objective lens with high NA) OL1 having a narrow pull-in range is at a position sufficiently retracted from the optical disc surface. Is located in.

When the optical disc is inserted, first, focusing control is performed by the second focusing means F2 equipped with the second objective lens OL2 having a wide pull-in range.
The optical disc is discriminated by confirming the output of the focus signal, and when the optical disc is the second optical disc, the optical disc is accessed as it is.

When it is determined that the optical disc is the first optical disc D1, the first focusing means F1 carrying the objective lens OL1 is brought close to the optical disc D1 to start access.

The arrangement is basically maintained until the optical disc is taken out, but in the event of an unexpected situation (for example, when the optical disc comes off the clamper), as an emergency evacuation measure for protecting the objective lens, It is conceivable that the first focusing means F1 equipped with the objective lens OL1 having a narrow pull-in range takes the avoidance state. Further, when the optical disk is taken out, the avoidance state is set.

A moving mechanism for moving the entire focusing means is required for the avoidance state and the access state. This is because if the objective lens is moved as an extension of the focusing operation, the cover of the actuator or the like may collide with the optical disc.

In the embodiment shown in FIG. 1, the first focusing means F1 is displaced, but conversely, the second focusing means F2 may be displaced. In this case, the height of the second objective lens having a wide pull-in range and the height of the first objective lens having a narrow pull-in range are substantially the same as the position of each focusing means before the optical disc is inserted, or It is set so that the position of the objective lens is on the optical disk side.

When the optical disk is inserted, the focusing operation of the second objective lens is executed as described above, and the type of the optical disk is determined by checking the output of the focus signal. When the determination result is the second optical disc, the optical disc is accessed as it is, and when the first optical disc is determined, the second focusing means having the second objective lens is moved away from the optical disc, and the "optical disc" will be described later. The position of “1” is brought closer to the optical pickup device ”or“ the optical pickup device is brought closer to the optical disc ”, and the access is started by the first objective lens. The arrangement is basically maintained until the disc is ejected.

By using the optical pickup device described above, it is possible to realize an optical information processing device (claim 5) for recording / reproducing / erasing information on / from plural kinds of optical disks.

FIG. 5 shows one form of a drive device as an optical information processing device according to a sixth aspect. Optical disc D
1 and D2 are held in a state of being selectively clamped by the clamper HL, and are rotated by the motor MT. Then, it is accessed by the optical pickup device PU. In this embodiment, the cam 30 is engaged with the support plate 20 on which the motor MT is fixed, and the rotation of the cam 30 causes the optical discs D1 and D2 to move in the rotational axis direction (the vertical direction in the figure, that is, It can be displaced in the focusing direction).

That is, this drive device is an optical information processing device for recording / reproducing / erasing information on / from a plurality of types of optical discs, and changes the relative distance between one or more focusing means and the optical disc. As a displacement mechanism, a mechanism 30 for changing the relative distance between the entire optical pickup and the optical disc holding mechanism in the focusing direction is provided.

Since a mechanism for moving up and down the clamper holding the optical disc (where the optical disc is placed) exists as a conventional loading mechanism, it can be used as it is.

As another example, instead of displacing the optical disk in the direction of the rotation axis, or at the same time when displacing the optical disk, a mechanism for supporting the optical pickup device PU is provided as a displacement mechanism T.
May be displaced in the focusing direction (vertical direction in the drawing).

At present, a mechanism is adopted in which the optical pickup device moves up and down when the optical disc is loaded to "avoid interference with the loading mechanism". The same gears are used to access the optical pickup device. It can be displaced to a fixed position by the optical disc.

When the optical disc is inserted, the optical pickup device is arranged at a position where the second objective lens having a wide pull-in range accesses the optical disc, and the optical disc is discriminated by checking the output of the focus signal. ,
When the optical disc D2 is discriminated, the optical pickup device is accessed as it is, and when the optical disc D1 to be supported by the first objective lens having a narrow pull-in range is discriminated, the optical pickup device is located at a position where the first objective lens accesses the optical disc D1. Is placed to approach the optical disc D1 and access is started with the first objective lens. The arrangement is basically maintained until the optical disk is ejected.

[0051]

As described above, according to the present invention, a novel optical pickup device and optical information processing device can be realized. According to the optical pickup device of the present invention, even when the objective lens having a large WD is switched and the access is performed, the WD can be accessed when the objective lens having a large WD is accessed.
Since the objective lens having a small size and its focusing means do not collide with the optical disc, the optical disc and the objective lens are not damaged and the reliability is high. Since the optical information processing apparatus of the present invention uses the above optical pickup device, it does not damage the optical disc or the objective lens and has high reliability.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a first embodiment of an optical pickup device.

FIG. 2 is a diagram showing only another characteristic part of another embodiment of the optical pickup device.

FIG. 3 is a diagram showing only a characteristic part of another embodiment of the optical pickup device.

FIG. 4 is a diagram showing only another characteristic part of another embodiment of the optical pickup device.

FIG. 5 is a diagram for explaining the first embodiment of the optical information processing device.

[Explanation of symbols] F1 First focusing means F2 Second focusing means

Claims (6)

[Claims] 1. An optical pickup device having a plurality of focusing means and a displacement mechanism for changing a relative distance between one or more focusing means and an optical disk. 2. A first objective lens, a first focusing means having a first focusing mechanism for keeping the distance between the first objective lens and the first optical disk constant, and a second objective lens. A second focusing mechanism having a second focusing mechanism for keeping the distance between the second objective lens and the second optical disk constant, and the retracting range of the second focusing mechanism is the same as that of the first focusing mechanism. It is larger than the pull-in range, and when the second objective lens accesses the second optical disc, the first objective lens or the first focusing means is arranged at a position where it does not come into contact with the second optical disc. Optical pickup device. 3. The optical pickup device according to claim 2, wherein, in a natural state, a distance between the first objective lens and the optical disc is equal to a distance between the second objective lens and the optical disc. Optical pickup device. 4. The optical pick-up device according to claim 2 or 3, wherein coarse movement displacement of the first objective lens in the focusing direction is performed in order to change the relative distance between the first objective lens and the optical disc. An optical pickup device comprising a mechanism and a fine movement displacement mechanism for performing fine movement displacement for focusing. 5. Optical information processing, characterized in that the optical pickup device according to any one of claims 2 to 4 is used to record / reproduce / erase information on / from a plurality of types of optical disks. apparatus. 6. An optical information processing apparatus for recording / reproducing / erasing information on / from a plurality of types of optical discs by using the optical pickup according to claim 1, comprising one or more focusing means and an optical disc. An optical information processing apparatus comprising a displacement mechanism that changes the relative distance between the entire optical pickup and the optical disc holding mechanism in the focusing direction, as a displacement mechanism that changes the relative distance of the optical pickup.