JP3599399B2 - Optical pickup device and optical recording medium discriminating device - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to an optical pickup apparatus and an optical recording medium discriminating apparatus, and more particularly to an optical pickup apparatus and a recording apparatus for reproducing information recorded on an optical recording medium having different distances (substrate thicknesses) from a recording medium surface to an information recording surface. The present invention relates to an optical recording medium discriminating apparatus for discriminating optical recording media having different distances (substrate thickness) from a medium surface to an information recording surface.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a reproducing apparatus for reproducing a plurality of types of optical recording media, a multi-disc player capable of reproducing a CD (Compact Disk), an LD (Laser Vision Disk) or the like has been known.
[0003]
In a conventional multi-disc player, a separate pickup device must be provided for each disc to provide an optimal optical system for discs having different thicknesses, refractive indexes, and the like of disc protective layers (substrates), and reproduction must be performed. Optimal reproduction is performed for each disk by selectively using a pickup device according to the disk.
[0004]
Further, in the conventional multi-disc player, when discs having different thicknesses are determined, a mechanical switch is provided, and the type of the loaded disc is determined based on whether or not this switch is pressed. I was Further, when the outer shape such as the outer diameter is different, an optical detecting means such as an optical sensor is provided to determine the type of the mounted disk by determining the presence or absence of reflected light.
[0005]
[Problems to be solved by the invention]
By the way, in the above-mentioned conventional multi-disc player, since a separate pickup device is provided for each disc, there is a problem that the device becomes large and the cost increases.
[0006]
To solve this problem, it is conceivable to use a common pickup device. However, if the thickness of the protective layer (substrate) of the disk is significantly different from the optimum thickness set for the pickup device, the pickup device may be used. There is a problem that spherical aberration occurs in the light beam.
[0007]
More specifically, the wavelength of the read light emitted from the laser diode is λ, the refractive index of the protective layer of the disk is n, and the difference between the thickness of the protective layer of the disk and the optimal thickness of the protective layer corresponding to the pickup device. Is Δd and the numerical aperture of the objective lens is NA, the spherical aberration W₄₀Is
W₄₀= ((N₂-1) / 8n³) ・ Δd ・ (NA⁴/ Λ)
The larger the difference Δd between the thickness of the protective layer of the disk and the optimum thickness of the protective layer corresponding to the pickup device, the larger the spherical aberration becomes, and the signal quality of the read signal deteriorates. was there.
[0008]
Further, in the above-mentioned conventional mechanical or optical disc discriminating apparatus, when discs having substantially the same thickness and reflectivity but differing only in the distance from the surface of the protective layer to the information recording surface are determined, the disc is recorded. Complicated discrimination, such as comparing formats, was required, and could not be easily discriminated by mechanical or optical discriminating means.
[0009]
More specifically, it is possible to discriminate between a double-sided disc in which two discs having the same outer diameter and the same thickness of the protective layer of 0.6 mm are bonded and a single-sided disc with the thickness of the protective layer of 1.2 mm. There was a problem that it was not possible.
[0010]
Therefore,The object of the present invention isIt is an object of the present invention to provide a pickup device capable of reproducing a plurality of types of disks having different protective layer thicknesses with one pickup device.
[0012]
[Means for Solving the Problems]
The above issuesTo solve the problem, the invention according to claim 1 emits read light in an optical pickup device for reproducing recorded information from a plurality of types of optical recording media having different distances from the surface of the optical recording medium to the information recording surface. A light source, an objective lens for condensing the readout light on the recording medium, and a plurality of optical elements; provided in an optical path between the light source and the objective lens, the readout light An optical element group leading to the objective lens, and, based on an optical recording medium discrimination signal from the outside, other than the at least some of the plurality of optical elements in place of at least some of the optical elements for correcting spherical aberration caused by the distance. Optical element switching means for inserting the optical element into the optical path, wherein the some optical elements and the other optical elements are collimator lenses having different optical constants, respectively. That.
[0017]
[Action]
According to the first aspect of the present invention, the light source emits the reading light, and the objective lens focuses the reading light on the optical recording medium.
At this time, the optical element switching means may be replaced with at least a part of the plurality of optical elements instead of at least some of the plurality of optical elements based on an external optical recording medium determination signal in order to correct spherical aberration caused by the distance. Insert the optical element into the optical path.
Some of the optical elements and other optical elements are collimator lenses having different optical constants. Therefore, since the spherical aberration can be corrected in accordance with the optical recording medium discrimination signal, optimal reproduction can be performed.
[0027]
【Example】
Next, a preferred embodiment of the present invention will be described with reference to the drawings.
First embodiment
FIG. 1 shows a schematic configuration diagram of the pickup device of the first embodiment.
[0028]
The pickup device 1 includes a laser diode 2 for emitting readout light, a grating 3 for separating the readout light into three beams, and a readout light from the laser diode 2 that reflects the light and guides it to an objective lens described later. A half mirror 4 that transmits readout light from the lens side, a collimator lens 5 that converts diffused readout light into parallel light, and an aberration correction element 6 for correcting spherical aberration such as a spherical lens or a Fresnel lens. Control signal S_CAnd a driving circuit 8 for driving the correction element driving mechanism 7 to insert or remove the aberration correction element 6 in the optical path, and for condensing the readout light on the optical disk DK. An objective lens 9, a concave lens 10 for beam shaping the read light from the objective lens 9 transmitted through the half mirror 4, and a light receiving element that receives the read light shaped by the concave lens 10, converts the read light into an electric signal, and outputs it 11 and disc type, and disc discrimination signal S_DAnd a disc discrimination signal S_DControl signal S for controlling insertion / removal of the spherical aberration correction element based on_CAnd a control circuit 13 that outputs the same.
[0029]
Here, the configuration of the disc determination sensor 12 will be described with reference to FIG.
As shown in FIG. 2A, the disc discrimination sensor 12 extracts only a low-frequency component from the current flowing through the focus coil that drives the objective lens 9 in the focusing direction, and outputs a low-frequency component signal as a low-frequency component signal. And the voltage V of the low-frequency component signal_DCIs the reference voltage V_REFIs compared with the disk discrimination signal S_DAnd a comparator 12B that outputs the same.
[0030]
As a result, the disc determination sensor 12 includes, for example, a DVD (Digital Video Disk) in which two discs each having a protective layer (substrate) thickness of 0.6 mm are bonded to each other and a CD (Compact Disk) having a protective layer thickness of 1.2 mm. Reference voltage V for determining_REFIs set, the voltage V of the low-frequency component signal corresponding to the protective layer thickness of 0.9 mm (= (0.6 + 1.2) / 2) is set._DCIs the reference voltage V_REFSet as
[0031]
Usually, since the protective layer has a refractive index n, the stroke (drive distance) d of the objective lens is substantially proportional to t / n when the incident angle of the beam is small, where t is the thickness of the protective layer. As a result, as shown in FIG. 2B, the drive distance of the lens when the focus servo is closed and the drive distance of the lens shown in FIG. As described above, in a CD having a protective layer thickness of 1.2 mm, the drive distance of the lens when the focus servo is closed is twice (=) when the focus position when the focus servo is not performed is the surface of the protective layer. 1.2 / 0.6 times).
[0032]
Therefore, the focus position when the focus servo is not performed is adjusted so as to be on the surface of the protective layer, and the voltage V of the low-frequency component signal is adjusted._DCVoltage V obtained as_MDCIs the reference voltage V_REFIs exceeded, a disc discrimination signal indicating that the disc is a CD is output, and the voltage V of the low-frequency component signal is output._DCVoltage V obtained as_MDCIs the reference voltage V_REFIs not exceeded, a disc discrimination signal indicating that the optical disc is a DVD is output.
[0033]
In the following description of the operation, the reference voltage V_REFIt is assumed that the above setting is performed.
Prior to information reproduction, the pickup device 1 closes the focus servo to bring the readout light into focus on the information recording surface of the optical disc DK, thereby bringing the optical disc DK into a focused state.
[0034]
As a result, the low-pass filter 12A of the disc discrimination sensor 12 extracts only the low-frequency component from the voltage signal corresponding to the current flowing through the focus coil that drives the objective lens 9 in the focusing direction, and outputs the low-frequency component signal to the comparator 12B. Output.
[0035]
Thereby, the comparator 12 outputs the voltage V of the low-frequency component signal._DCIs the reference voltage V_REFThen, a discrimination signal corresponding to the type of the loaded optical disc is output to the control circuit 13.
[0036]
More specifically, the voltage V of the low-frequency component signal_DCVoltage V obtained as_MDCIs the reference voltage V_REFIs exceeded, a disc discrimination signal indicating that the optical disc is a CD is output to the control circuit 13, and the voltage V of the low-frequency component signal is output._DCVoltage V obtained as_MDCIs the reference voltage V_REFIf the number does not exceed the predetermined value, a disc discrimination signal indicating that the disc is a DVD is output to the control circuit 13.
[0037]
Thereby, the control circuit 13 outputs a control signal for controlling the insertion / removal of the spherical aberration correction element to the drive circuit 8 based on the disc discrimination signal.
As a result, the drive circuit 8 outputs a drive control signal to the correction element driving mechanism 7 based on the control signal, and inserts or removes the aberration correction element 6 into or from the optical path according to the disc discrimination signal.
[0038]
Specifically, when the aberration correction element is not inserted in the optical path and the optimal optical system for the CD is set, as shown in FIG. When the aberration correction element 6 is not inserted in the optical path, the state is kept as it is, and when the aberration correction element 6 is inserted in the optical path, the aberration correction element 6 is extracted from the optical path. .
[0039]
Also, according to the disc discrimination signal, when the mounted optical disc is a DVD, if the aberration correction element 6 is not inserted in the optical path, the aberration correction element 6 is inserted in the optical path, and the aberration is detected in the optical path. When the correction element 6 is inserted, the aberration correction element 6 is left as it is.
[0040]
As described above, according to the first embodiment, the type of the loaded optical disc is detected only from the difference in the thickness of the protective layer, and the optimal aberration correction is performed. Can be easily performed.
[0041]
In the first embodiment, the case where two types of optical disks (CD and DVD) having different protective layer thicknesses are determined has been described. However, a plurality of reference voltages are set in the comparator 12B, and three or more types of optical disks are determined. Then, it is also possible to configure so as to switch the aberration correction element.
Second embodiment
FIG. 4 shows a schematic configuration diagram of the pickup device of the second embodiment. In FIG. 4, the same parts as those in the first embodiment of FIG. 1 are denoted by the same reference numerals, and the discs to be mounted are two types of CD and DVD.
[0042]
The pickup device 20 includes a laser diode 2 for emitting readout light, a grating 3 for separating the readout light into three beams, and a readout light from the laser diode 2 that reflects the light and guides the readout light to an objective lens described later. A half mirror 4 that transmits readout light from the lens side, a first collimator lens A that has an optical constant suitable for CD and converts parallel readout light as diffused light, and an optical constant suitable for DVD. A second collimator lens B for converting read light, which is diffused light, into parallel light, and a drive control signal based on the control signal, and driving the correction element drive mechanism 7A to drive the first collimator lens A and the second collimator. A driving circuit 8A for switching the lens B, an objective lens 9 for condensing the reading light on the optical disk DK, and reading from the objective lens 9 transmitted through the half mirror 4. The concave lens 10 for beam shaping, the light receiving element 11 for converting into an electric signal by receiving the reading light shaped by the concave lens 10, to determine the disc type, the disc discrimination signal S_DAnd a control circuit 13 that outputs a control signal for controlling the insertion and removal of the spherical aberration correction element based on the disc discrimination signal.
[0043]
Prior to information reproduction, the pickup device 1 closes the focus servo in order to focus on the information recording surface of the optical disc DK.
Thereby, the low-pass filter 12A of the disc discrimination sensor 12 extracts only the low-frequency component from the current flowing through the focus coil that drives the objective lens 9 in the focusing direction, and outputs the low-frequency component signal to the comparator 12B.
[0044]
Thereby, the comparator 12B changes the voltage VDC of the low-frequency component signal to the reference voltage V_REFAnd outputs a disc identification signal corresponding to the type of the loaded optical disc to the control circuit 13 which outputs the discrimination signal.
[0045]
More specifically, the voltage V of the low-frequency component signal_DCVoltage V obtained as_MDCIs the reference voltage V_REFIs exceeded, a disc discrimination signal indicating that the optical disc is a CD is output to the control circuit 13, and the voltage V of the low-frequency component signal is output._DCVoltage V obtained as_MDCIs the reference voltage V_REFIf the number does not exceed the predetermined value, a disc discrimination signal indicating that the disc is a DVD is output to the control circuit 13.
[0046]
Accordingly, the control circuit 13 outputs a control signal for controlling switching of the collimator lens based on the disc discrimination signal to the drive circuit 8A.
As a result, the drive circuit 8A outputs a drive control signal to the correction element drive mechanism 7 based on the control signal, and switches the collimator lens corresponding to the loaded disc in accordance with the disc discrimination signal.
[0047]
More specifically, as shown in FIG. 5, when the mounted optical disk is a CD, if the first collimator lens A is inserted in the optical path, it is left as it is according to the disk determination signal. When the second collimator lens B is inserted in the optical path, the second collimator lens B is switched to the first collimator lens A.
[0048]
Also, according to the disc discrimination signal, when the mounted optical disc is a DVD, the first collimator lens A is switched to the second collimator lens B when the first collimator lens A is inserted in the optical path, If the second collimator lens B is inserted in the optical path, it is left as it is.
[0049]
As described above, according to the second embodiment, the type of the loaded optical disc is detected only from the difference in the thickness of the protective layer, and the optimal collimator lens is switched. Can be easily performed.
[0050]
In the second embodiment, the case where the collimator lens is switched corresponding to two types of optical disks (CD and DVD) having different protective layer thicknesses has been described. However, a plurality of collimator lenses are prepared and three or more types of optical disks are used. , And the collimator lens can be switched.
[0051]
Further, in the second embodiment, the case where the collimator lens is switched has been described. However, it is also possible to configure such that another optical element is switched.
Third embodiment
In the above-described first and second embodiments, a case has been described in which the optical system other than the aberration correction element or the collimator lens is a single system. However, the third embodiment is an embodiment in which two light-emitting systems are provided. It is an example.
[0052]
FIG. 6 shows a schematic configuration diagram of the pickup device of the third embodiment. In FIG. 6, the same parts as those in the first embodiment of FIG. 1 are denoted by the same reference numerals, and the discs to be mounted are two types of CDs and DVDs.
[0053]
The pickup device 30 includes a first laser diode 2A that emits read light, a first drive circuit 31A that drives the first laser diode, and a first laser diode 2A that separates read light from the first laser diode 2A into three beams. A first grating 3A, a first collimator lens 32A having an optical constant suitable for the CD, and parallelizing the readout light, which is the diffused light from the first laser diode 2A, and a second laser diode 2B for emitting the readout light A second drive circuit 31B for driving the second laser diode 2B, a second grating 3B for separating the read light from the second laser diode 2B into three beams, and a diffused light from the first laser diode 2A. And a second collimator lens 32B that converts the read light into parallel light, and a read light from the first collimator lens 32A, A first beam splitter 33 that reflects the readout light from the two-collimator lens 32B, a second beam splitter 34 that transmits the readout light from the beam splitter 33 and transmits readout light from the objective lens described later, and readout light Lens 9 for condensing the light on the optical disk DK, a concave lens 10 for beam shaping the read light from the objective lens 9 transmitted through the half mirror 4, and receiving the read light shaped by the concave lens 10. A light receiving element 11 for converting the signal into an electric signal and outputting the signal; a disc discriminating sensor 12 for discriminating the disc type and outputting a disc discriminating signal; And a control circuit 13 that outputs a control signal for controlling the operation.
[0054]
Prior to information reproduction, the pickup device 30 closes the focus servo in order to focus read light on the information recording surface of the optical disc DK.
Thereby, the low-pass filter 12A of the disc discrimination sensor 12 extracts only the low-frequency component from the current flowing through the focus coil that drives the objective lens 9 in the focusing direction, and outputs the low-frequency component signal to the comparator 12B.
[0055]
Thereby, the comparator 12 outputs the voltage V of the low-frequency component signal._DCIs the reference voltage V_REFAnd outputs a disc identification signal corresponding to the type of the loaded optical disc to the control circuit 13 which outputs the discrimination signal.
[0056]
More specifically, the voltage V of the low-frequency component signal_DCVoltage V obtained as_MDCIs the reference voltage V_REFIs exceeded, a disc discrimination signal indicating that the optical disc is a CD is output to the control circuit 13, and the voltage V of the low-frequency component signal is output._DCVoltage V obtained as_MDCIs the reference voltage V_REFIf the number does not exceed the predetermined value, a disc discrimination signal indicating that the disc is a DVD is output to the control circuit 13.
[0057]
Thereby, the control circuit 13 selectively outputs a control signal to either the first drive circuit 31A or the second drive circuit 31B based on the disc discrimination signal.
As a result, one of the selected driving circuits drives the corresponding laser diode to perform reproduction.
[0058]
More specifically, when the optical disc mounted by the disc discrimination signal is a CD, as shown in FIG. 7A, the first drive circuit 31A is driven to read light to the first laser diode 2A. For reproduction.
[0059]
If the optical disc mounted by the disc discrimination signal is a DVD, the second drive circuit 31B is driven to cause the second laser diode 2B to emit readout light, as shown in FIG. 7B. Perform playback.
[0060]
As described above, according to the third embodiment, the type of the loaded optical disc is detected only from the difference in the thickness of the protective layer, and the optimal light emitting optical system is switched. Can be easily performed.
[0061]
In the third embodiment, the case where the light emitting optical system is switched corresponding to two types of optical disks (CD and DVD) having different protective layer thicknesses has been described. It is also possible to determine the above optical disc and switch the light emitting optical system.
Fourth embodiment
FIG. 8 is a schematic block diagram of a pickup device according to a fourth embodiment.
[0062]
In the third embodiment, two or more light emitting optical systems including a driving circuit are provided. However, the fourth embodiment is an embodiment in which the driving circuit is shared and the circuit configuration is simplified. is there. In the fourth embodiment, the same parts as those in the third embodiment in FIG. 6 are denoted by the same reference numerals, and the discs to be mounted are two types of CDs and DVDs.
[0063]
The pickup device 40 has a first laser diode 2A for emitting readout light, a first grating 3A for separating the readout light from the first laser diode 2A into three beams, and an optical constant suitable for CD. A first collimator lens 32A for converting the reading light, which is diffused light from the first laser diode 2A, into parallel light, a second laser diode 2B for emitting the reading light, and the first laser diode 2A or the second laser diode 2B. Drive circuit 4 for driving1A second grating 3B for separating the reading light from the second laser diode 2B into three beams, and a reading light which has an optical constant suitable for DVD and is diffused light from the first laser diode 2A. A second collimator lens 32B that converts the light into parallel light, a first beam splitter 33 that transmits readout light from the first collimator lens 32A and reflects readout light from the second collimator lens 32B, and readout light from the beam splitter 33 , A second beam splitter 34 that transmits readout light from the objective lens side described later, an objective lens 9 for condensing the readout light on the optical disk DK, and an objective lens 9 that transmits the half mirror 4. A concave lens 10 for beam-shaping the read light, receiving the read light shaped by the concave lens 10, converting the read light into an electric signal, and outputting the electric signal. An optical element 11, a disc discrimination sensor 12 for discriminating a disc type and outputting a disc discrimination signal, and a switching circuit 42 for connecting the drive circuit 41 to the first laser diode 2A or the second laser diode 2B based on the disc discrimination signal. And is provided.
[0064]
Prior to information reproduction, the pickup device 40 closes the focus servo in order to focus the read light on the information recording surface of the optical disc DK.
Thereby, the low-pass filter 12A of the disc discrimination sensor 12 extracts only the low-frequency component from the current flowing through the focus coil that drives the objective lens 9 in the focusing direction, and outputs the low-frequency component signal to the comparator 12B.
[0065]
Thereby, the comparator 12 outputs the voltage V of the low-frequency component signal._DCIs the reference voltage V_REFThen, a discrimination signal corresponding to the type of the loaded optical disc is output to the switching circuit 42.
[0066]
More specifically, the voltage V of the low-frequency component signal_DCVoltage V obtained as_MDCIs the reference voltage V_REFIs exceeded, a disc discrimination signal indicating that the disc is a CD is output to the switching circuit 42, and the voltage V of the low-frequency component signal is output._DCVoltage V obtained as_MDCIs the reference voltage V_REFIf the number does not exceed the threshold value, a discrimination signal indicating that the optical disc is a DVD is output to the switching circuit 42.
[0067]
Thereby, the switching circuit 42 selectively outputs the drive circuit 41 to either the first laser diode 2A or the second laser diode 2B based on the disc discrimination signal.
[0068]
As a result, one of the selected laser diodes is driven to perform reproduction.
More specifically, when the optical disk mounted according to the disk determination signal is a CD, the drive circuit 41 drives the first laser diode 2A and causes the first laser diode 2A to emit readout light to perform reproduction. .
[0069]
When the optical disc mounted according to the disc discrimination signal is a DVD, the drive circuit 41 drives the second laser diode 2B and causes the second laser diode 2B to emit reading light to perform reproduction.
[0070]
As described above, according to the fourth embodiment, the type of the mounted optical disk is detected only from the difference in the thickness of the protective layer, and the optimal light emitting optical system (laser diode) is driven. Therefore, it is possible to easily perform the optimum reproducing operation.
[0071]
In the fourth embodiment, a case has been described in which the drive circuit switches the laser diode to be driven in accordance with two types of optical disks (CD and DVD) having different protective layer thicknesses. It is also possible to make a configuration such that the laser diode to be driven is switched upon discrimination.
Fifth embodiment
FIG. 9 is a schematic operation explanatory view of the pickup device of the fifth embodiment. In FIG. 9, the same parts as those in the schematic operation explanatory view of the third embodiment of FIG. 7 are denoted by the same reference numerals.
[0072]
The fifth embodiment of FIG. 9 differs from the third embodiment of FIG. 7 in that a half mirror 51 is provided instead of the first beam splitter 33.
The other components and operations are the same as those in FIG. 7, and a detailed description thereof will be omitted.
[0073]
According to the fifth embodiment, as in the third embodiment, the type of the mounted optical disk is detected only from the difference in the thickness of the protective layer, and the optical system is switched to the optimal light emitting optical system. Optimal reproduction operation can be easily performed.
[0074]
In the fifth embodiment, the case where the light emitting optical system is switched corresponding to two types of optical disks (CD and DVD) having different protective layer thicknesses has been described. It is also possible to determine the above optical disc and switch the light emitting optical system.
[0075]
【The invention's effect】
According to the first aspect of the present invention, the optical element switching means, based on an optical recording medium discrimination signal from the outside, outputs a plurality of optical elements from the surface of the optical recording medium mounted on the device to the information recording surface. In order to correct the spherical aberration caused by the distance, another optical element is inserted in the optical path instead of at least a part of the optical elements, and the some optical elements and the other optical elements have optical constants, respectively. Since different collimator lenses can correct spherical aberration in accordance with the optical recording medium discrimination signal, optimal reproduction can be performed.
[Brief description of the drawings]
FIG. 1 is a schematic configuration block diagram of a pickup device according to a first embodiment.
FIG. 2 is an explanatory diagram of an operation of a disk discrimination sensor.
FIG. 3 is an operation explanatory diagram of the first embodiment.
FIG. 4 is a schematic configuration block diagram of a pickup device according to a second embodiment.
FIG. 5 is an operation explanatory diagram of the second embodiment.
FIG. 6 is a schematic configuration block diagram of a pickup device according to a third embodiment.
FIG. 7 is an operation explanatory diagram of the third embodiment.
FIG. 8 is a schematic configuration block diagram of a pickup device according to a fourth embodiment.
FIG. 9 is an operation explanatory diagram of the fifth embodiment.
[Explanation of symbols]
1 ... Pickup device
2 ... Laser diode
3 ... Grating
3A: 1st grating
3B: 2nd grating
4: Half mirror
5. Collimator lens
6 ... Aberration correction element
7. Correction element drive mechanism
8. Drive circuit
8A ... Drive circuit
9 ... Objective lens
10 ... concave lens
11 ... Light receiving element
12 ... Disk discrimination sensor
12A: Low-pass filter
12B ... Comparator
13. Control circuit
20 ... Pickup device
30 ... Pickup device
31A: First drive circuit
31B: Second drive circuit
32A: First collimator lens
32B ... second collimator lens
33 ... First beam splitter
34 second beam splitter
40 ... Pickup device
41 ... Drive circuit
42 ... Switching circuit
51: Half mirror
DK: Optical disk
S_C…Control signal
S_D… Disc identification signal
V_DC... Low-frequency component signal voltage
V_REF… Reference voltage

Claims (1)

In an optical pickup device for reproducing recorded information from a plurality of types of optical recording media having different distances from the surface of the optical recording medium to the information recording surface,
A light source for emitting reading light;
An objective lens for condensing the read light on the recording medium,
An optical element group comprising a plurality of optical elements, provided in an optical path between the light source and the objective lens, and guiding the readout light to the objective lens;
Based on an optical recording medium discrimination signal from the outside, among the plurality of optical elements, another optical element is inserted into the optical path instead of at least a part of the optical elements in order to correct spherical aberration caused by the distance. Optical element switching means,
The optical pickup device, wherein the some optical elements and the other optical elements are collimator lenses having different optical constants.

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