JP4672954B2 - Optical pickup device and optical information processing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical pickup device and an optical information processing device.
[0002]
[Prior art]
In addition to conventional CDs (compact discs), DVDs (digital video discs) with higher recording densities have been put to practical use as optical discs, and the realization of next-generation high-density optical discs with higher recording densities is intended. Has been.
[0003]
When a next-generation optical disk with an increased storage capacity appears, it is preferable that a “drive device” that performs recording / reproduction with respect to the optical disk can also perform recording / reproduction with respect to a conventional DVD or CD as an optical disk. When the next generation optical disc of DVD appears, it is considered that the drive device is also required to have a drive function for DVD and CD.
[0004]
An orthodox method for realizing high recording density is to reduce the spot diameter of a light spot for recording / reproducing on an optical disk. To reduce the spot diameter, a method for shortening the recording wavelength, a method for increasing the numerical aperture (hereinafter referred to as NA) of the objective lens for condensing the light spot, or a method for shortening the recording wavelength and increasing the NA. A method is conceivable.
[0005]
In general, the NA of an objective lens is proportional to the effective radius of the objective lens: r and inversely proportional to the focal length: f. Therefore, when the NA of the objective lens is increased, the focal length: f is shortened when the lens diameter is assumed to be constant. As a result, the working distance between the optical disk and the objective lens (hereinafter referred to as WD) is reduced. Shorter.
[0006]
The next generation of optical discs with higher recording density has appeared, and it is possible to record and play back this and conventional CDs and DVDs using the same drive device, which is compatible with conventional optical discs (CD and DVD). The conventional objective lens and the high NA objective lens for high recording density are used. The conventional objective lens is used for accessing the conventional optical disk, and the high NA is used for accessing the high recording density optical disk. Although it has a configuration using an objective lens, since a high NA objective lens has a short WD, when accessing a conventional optical disc, there is a possibility that the high NA objective lens may collide with the conventional optical disc simply by being present there. Comes out.
[0007]
[Problems to be solved by the invention]
In an optical pickup device having a plurality of objective lenses having a large working distance (for example, 0.5 mm or more), when an objective optical disk is accessed by a certain objective lens, other objective lenses or lens holders may collide with the optical disk. It is an object of the present invention to realize a highly reliable optical pickup device that avoids and does not damage the optical disk and the objective lens.
[0008]
Another object of the present invention is to realize a highly reliable optical information processing device (drive device) that does not damage the optical disk and the objective lens.
[0009]
[Means for Solving the Problems]
The 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 the one or more focusing means and the optical disk”.
[0010]
The optical pickup device according to claim 1 has first and second focusing means.
The “first focusing means” includes 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 disk constant. A “first optical disk” is one or more optical disks that are accessible using a first objective lens.
[0011]
The “second focusing means” includes 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 disk” is one or more optical disks that are accessible using a second objective lens.
[0012]
The pulling range of the second focusing mechanism is larger than the pulling range of the first focusing mechanism. When the second objective lens accesses the second optical disk, the first objective lens or the first focusing means 2 ”is arranged at a position not in contact with the optical disc 2.
[0013]
The optical pickup apparatus of claim 1, wherein the "distance between the first objective lens and the optical disk, the distance between the second objective lens and the optical disc is equal arbitrarily" in nature. The “natural state” is a state where the driving force by the focusing mechanism is not received (claim 2) .
[0014]
In order to change the relative distance between the first objective lens and the optical disc , the optical pickup device according to claim 1 is provided with a “coarse displacement mechanism for coarsely displacing the first objective lens in the focusing direction, and for focusing. fine displacement mechanism to fine displacement and "to have a.
[0015]
According to a third aspect of the present invention, there is provided an optical information processing apparatus using the optical pick-up apparatus according to the first or second aspect, wherein at least one information recording / reproducing / erasing is performed on at least the first optical disc and the second optical disc It is characterized by performing.
[0016]
The optical information processing apparatus according to claim 4 is an optical pickup apparatus that accesses at least the first optical disc and the second optical disc, and includes a first objective lens, the first objective lens, and the first objective lens. A first focusing means having a first focusing mechanism for maintaining a constant distance from the optical disc, a second objective lens, and a distance between the second objective lens and the second optical disc; A second focusing means having a second focusing mechanism having a drawing range larger than a drawing range of the first focusing mechanism, and in a natural state, a distance between the first objective lens and the optical disc, The distance between the second objective lens and the optical disc is equal, and the first objective lens or the first focusing means is in contact with the optical disc. A coarse displacement mechanism for coarsely displacing the first objective lens in a focusing direction in order to change a relative distance between the first objective lens and the optical disc, Therefore, the optical disc is moved by the second focusing means while the first objective lens or the first focusing means is disposed at a position not in contact with the optical disc. An optical pickup device that determines whether the optical disk is a first optical disk and accesses the first optical disk by bringing the first objective lens or the first focusing means closer to the first optical disk when the optical disk is the first optical disk the use, recording and information for at least the first optical disk and the second optical disk An optical information processing apparatus that performs one or more of live / erasure, and a relative distance in the focusing direction between the entire optical pickup and the optical disk holding mechanism as a displacement mechanism that changes the relative distance between the one or more focusing means and the optical disk It has the mechanism which changes.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an embodiment of an optical pickup device. In order to avoid complication of the figure, only the basic optical arrangement is shown schematically. As the specific optical arrangement, various conventionally known optical arrangements can be used as appropriate.
[0018]
In the figure, reference numerals D1 and D2 indicate first and second optical disks, respectively. The “first focusing means” denoted by reference numeral F1 includes a first objective lens OL1 and a “first focusing mechanism (not shown) that keeps the distance between the first objective lens OL1 and the first optical disc D1 constant. ) ”.
[0019]
The “second focusing means” denoted by reference numeral F2 includes a second objective lens OL2 and a “second focusing mechanism (not shown) that keeps the distance between the second objective lens OL2 and the second optical disk D2 constant. ) ”.
[0020]
As the first and second focusing mechanisms, conventionally known appropriate mechanisms 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 pull-in range of the second focusing mechanism used in the second focusing means F2 is the first This is larger than the pull-in range of the first focusing mechanism used for the focusing means F1.
[0021]
The focusing means refers to the whole of the lens barrel and the casing housing these, in addition to the objective lens and the focusing mechanism.
[0022]
When the first optical disk D1 is accessed (recording / reproducing / erasing is performed), the semiconductor laser OR1 is driven. The emitted light beam is collimated by the collimator lens C1, reflected by the polarization beam splitter PBS1 toward the objective lens OL1, passes through the quarter-wave plate WP1, and is reflected on the recording surface of the first optical disc D1 by the objective lens OL1. The light is condensed as a light spot.
[0023]
The reflected light from the recording surface becomes a return light beam, passes through the objective lens OL1, returns to the polarization beam splitter PBS1 through the quarter-wave plate WP1, passes through this, and enters the light detection element PD1 through the detection lens L1. Various signals (RF signal, focusing signal, tracking signal) are generated.
[0024]
The semiconductor laser OR2 is driven when accessing the second optical disk D2 (performing recording / reproducing / erasing). The emitted light beam passes through the polarization hologram H2, and is condensed as a light spot on the recording surface of the second optical disc D2 by the objective lens OL2 via the quarter-wave plate WP2.
[0025]
The reflected light from the recording surface becomes a return light beam, passes through the objective lens OL2, is diffracted by the polarization hologram H2 via the quarter-wave plate WP2, and enters the light detection element PD2 to generate various signals similar to the above. .
[0026]
In FIG. 1A, reference numeral 10 denotes a housing of the optical pickup device.
[0027]
As shown in FIG. 1 (b), in the natural state, the distance between the first objective lens OL1 and the optical disk D1, the distance between the second objective lens OL2 and the optical disk D2 substantially equal (claim 1) . When accessing the optical disc D2, the objective lens OL2 is controlled by the second focusing mechanism in the state shown in FIG. 1B. The WD of the objective lens OL2 is large and the pull-in range of the second focusing mechanism is large. At this time, the first focusing means F1 including the first objective lens OL1 is positioned sufficiently away from the optical disc D2 (second Since the first focusing means F1 does not collide with the optical disk D2, the first focusing means F1 does not collide with the optical disk D2.
[0028]
When accessing the first optical disk D1, as shown in FIG. 1 (c), the first focusing means F1 is displaced in the focusing direction by a known appropriate displacement means (not shown), and the optical disk D1. The focusing control is enabled by the WD of the objective lens OL1. In this state, access is performed.
[0029]
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.
In order to change the relative distance between the first objective lens OL1 and the optical disc D1, a coarse displacement mechanism (comprising an actuator AC and a coarse motion signal generation circuit KS) that coarsely displaces the objective lens OL1 in the focusing direction; , and a fine displacement mechanism for the fine displacement for focusing (composed of actuator AC fine movement signal generating circuit KB) (claim 1).
[0030]
When the second objective lens OL2 having a wide pull-in range accesses the second optical disc D2 or is in a standby state, the first objective lens OL1 having a narrow pull-in range is connected to the second objective lens OL2 (in the focusing direction). Located at approximately the same position. Only when the optical disc D1 to be supported is inserted with the first objective lens having a narrow pull-in range, a predetermined amount (0.5 to 1 mm) is applied to the optical disc D1 by passing a predetermined current from the coarse motion signal generation circuit KS to the focusing coil of the actuator AC. The objective lens OL1 is displaced so as to approach, and the magnetic circuit of the actuator AC is designed so that the position of the objective lens OL1 at that time becomes “a nominal position when accessing the first optical disc D1”. Is focused on the first optical disc D1 by a fine movement signal (focusing signal) from the fine movement signal generation circuit KB.
[0031]
FIG. 3 shows another embodiment of the optical pickup device. In this embodiment, there is a step on the upper surface of the upper casing UK of the optical pickup device, and this step is smoothly connected. When the first optical disk is accessed, the first focusing means F1 and the second focusing means F2 are both located at the “top of the step” as shown in FIG. At this time, the part where the first focusing means F1 is located is the access position.
Therefore, the access to the first optical disk is executed in the state shown in FIG.
[0032]
When accessing the second optical disk, the first and second focusing means F1, F2 are displaced as shown in FIG. 3B, the first focusing means F1 is moved to the lower part of the step, and the second optical disk is accessed. 2 is retracted from the optical disk. Then, the second focusing means F2 is positioned at the access position. In this state, access is made by the objective lens OL2.
[0033]
FIG. 4 shows another embodiment of the optical pickup device.
In this embodiment, the first objective lens OL1 and its focusing means (first focusing means not shown), the second objective lens OL2 and its focusing means (second focusing means not shown) are provided. The displacement unit UT is unitized and “displaceable in the focusing direction (vertical direction in the figure) in units of the displacement unit UT” by an appropriate displacement mechanism M using a cam, a gear, or the like.
[0034]
As shown in FIG. 4A, when accessing the second optical disc D2, the displacement unit UT can take a distance from the optical disc D2 in accordance with the WD of the second objective lens OL2. At this time, since the first objective lens OL1 is disposed sufficiently away from the optical disc D2, the first objective lens OL1 does not collide with the optical disc D2 by the drawing operation of the objective lens OL2.
[0035]
When accessing the first optical disc D1, the displacement unit UT is displaced toward the first optical disc D1 by the displacement mechanism M, and the distance from the optical disc D1 is taken in accordance with the WD of the first objective lens OL1. . In this state, access to the optical disc D1 is performed.
[0036]
Each of the optical pickup devices described with reference to FIGS. 1, 3, and 4 has a plurality of focusing means and a displacement mechanism that changes the relative distance between one or more focusing means and the optical discs D1 and D2. (Claim 1).
[0037]
In each of the embodiments described above, before the optical disc is inserted, the first focusing means F1 mounting the objective lens (high NA objective lens) OL1 having a narrow pull-in range is disposed at a position sufficiently retracted from the optical disc surface. The
[0038]
When the optical disk 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, and the optical disk is discriminated by confirming how the focus signal is output. Is the second optical disk, it is accessed as it is.
[0039]
When it is determined that the optical disk is the first optical disk D1, the first focusing means F1 on which the objective lens OL1 is mounted is brought close to the optical disk D1 and access is started.
[0040]
The arrangement is basically maintained until the optical disk is removed. However, if an unexpected situation occurs (for example, if the optical disk is removed from the clamper), as an emergency evacuation measure to protect the objective lens, It is conceivable that the first focusing means F1 mounted with the narrow objective lens OL1 takes an avoidance state. Further, when the optical disk is taken out, the avoidance state is entered.
[0041]
This avoidance state and access state require a moving mechanism for moving the entire focusing means. This is because if only the objective lens is moved as an extension of the focusing operation, the cover of the actuator may collide with the optical disc.
[0042]
In the embodiment of FIG. 1, the first focusing means F1 is displaced, but conversely, the second focusing means F2 may be displaced. In this case, as the position of each focusing means before the optical disc is inserted, the heights of the second objective lens having a wide pulling range and the first objective lens having a narrow pulling range are approximately the same, or the second The position of the objective lens is set to be on the optical disc side.
[0043]
When the optical disk is inserted, the focusing operation of the second objective lens is executed in the same manner as described above, and the type of the optical disk is determined by confirming how the focus signal is output. When the discrimination result is the second optical disc, the access is made as it is. When the first optical disc is discriminated, the second focusing means on which the second objective lens is mounted is moved away from the optical disc. The access is started with the first objective lens by moving the position of the optical pickup device close to the optical pickup device or by bringing the optical pickup device closer to the optical disc. The arrangement is basically maintained until the disc is removed.
[0044]
By using the optical pickup device described above, it is possible to realize an optical information processing device that performs one or more of recording / reproducing / erasing information on a plurality of types of optical discs ( claim 3 ).
[0045]
FIG. 5 shows one form of a drive device as an optical information processing device according to claim 4 .
The optical disks D1 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 rotation axis direction (vertical direction in the figure, ie, It can be displaced in the focusing direction).
[0046]
That is, this drive device is an optical information processing device that performs one or more of recording / reproducing / erasing information on a plurality of types of optical disks, and is a displacement mechanism that changes the relative distance between one or more focusing means and the optical disk. And a mechanism 30 for changing a relative distance between the entire optical pickup and the optical disc holding mechanism in the focusing direction.
[0047]
A mechanism for moving up and down a clamper (where an optical disk is placed) that holds an optical disk exists as a loading mechanism in the prior art, and can be used as it is.
[0048]
As another example, the mechanism that supports the optical pickup device PU is displaced in the focusing direction (vertical direction in the figure) by the displacement mechanism T instead of or simultaneously with the displacement of the optical disk in the direction of the rotation axis. May be.
[0049]
Currently, the optical pickup device moves up and down at the time of loading the optical disc, and a mechanism that “avoids interference with the loading mechanism” is employed. However, the same gear is used to determine the optical disc that accesses the optical pickup device. Can be displaced to a different position.
[0050]
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 confirming the output of the focus signal, etc. If the optical disc D1 that should be handled by the first objective lens with a narrow pull-in range is discriminated, the optical pickup device is arranged at a position where the first objective lens accesses the optical disc D1. Then, access to the optical disc D1 is started, and access is started with the first objective lens. The arrangement is basically maintained until the optical disc is taken out.
[0051]
【The invention's effect】
As described above, according to the present invention, a novel optical pickup device and optical information processing device can be realized. In the optical pickup device of the present invention, even when an objective lens having a large WD is switched and accessed, the objective lens having a small WD and its focusing means do not collide with the optical disc when accessed by the objective lens having a large WD. The optical disk and the objective lens are not damaged, and the reliability is high. The optical information processing apparatus according to the present invention uses the optical pickup apparatus described above, and therefore does not damage the optical disk or the objective lens and has high reliability.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a first embodiment of an optical pickup device.
FIG. 2 is a diagram showing only another feature of another embodiment of the optical pickup device.
FIG. 3 is a diagram showing only another characteristic part of another embodiment of the optical pickup device.
FIG. 4 is a diagram showing only another feature of another embodiment of the optical pickup device.
FIG. 5 is a diagram for explaining one embodiment of an optical information processing apparatus;
[Explanation of symbols]
F1 first focusing means F2 second focusing means

Claims (4)

An optical pickup device that accesses at least a first optical disc and a second optical disc,
A first focusing means having a first focusing mechanism, and a first focusing mechanism for maintaining a constant distance between the first objective lens and the first optical disc;
A second objective lens, and a second focusing mechanism that maintains a constant distance between the second objective lens and the second optical disc and has a drawing range larger than a drawing range of the first focusing mechanism. Two focusing means,
In a natural state, 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, and the first objective lens or the first focusing means is used. It is in a state where it is placed in a position where it does not come into contact with the optical disc,
A coarse displacement mechanism that coarsely displaces the first objective lens in a focusing direction in order to change a relative distance between the first objective lens and the optical disc; and a fine displacement mechanism that finely displaces the first objective lens for focusing. Have
Determining whether the optical disk is the first optical disk by the second focusing means in a state where the first objective lens or the first focusing means is arranged in a position not in contact with the optical disk;
An optical pick-up apparatus that performs access by bringing the first objective lens or the first focusing means close to the first optical disk when the optical disk is the first optical disk. The optical pickup device according to claim 1,
The natural state is a state where the first objective lens is not receiving a driving force by the first focusing mechanism and the second objective lens is not receiving a driving force by the second focusing mechanism. An optical pickup device characterized by that. 3. An optical information processing apparatus using the optical pick-up apparatus according to claim 1 or 2 , wherein at least one of information recording, reproduction, and erasing is performed on at least the first optical disc and the second optical disc . An optical pickup device that accesses at least a first optical disc and a second optical disc,
A first focusing means having a first focusing mechanism, and a first focusing mechanism for maintaining a constant distance between the first objective lens and the first optical disc;
A second objective lens, and a second focusing mechanism that maintains a constant distance between the second objective lens and the second optical disc and has a drawing range larger than a drawing range of the first focusing mechanism. Two focusing means,
In a natural state, 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, and the first objective lens or the first focusing means is used. It is in a state where it is placed in a position where it does not come into contact with the optical disc,
A coarse displacement mechanism that coarsely displaces the first objective lens in a focusing direction in order to change a relative distance between the first objective lens and the optical disc; and a fine displacement mechanism that finely displaces the first objective lens for focusing. Have
Determining whether the optical disk is the first optical disk by the second focusing means in a state where the first objective lens or the first focusing means is arranged in a position not in contact with the optical disk;
When the optical disc is the first optical disc, an optical pickup device that accesses the first objective lens or the first focusing means close to the first optical disc is used, and at least the first optical disc is used. an optical information processing apparatus for performing one or more of the recording, reproducing, and erasing of the second optical disc to the information,
An optical information processing apparatus having a mechanism for changing a relative distance between the entire optical pickup and the optical disc holding mechanism as a displacement mechanism for changing a relative distance between one or more focusing means and the optical disc. .

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