JPH1064166A - Disc playback device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To enable effective use of the immediately preceding disc type detection result or the like at the time of power-on or reset release, and to promptly shift to the next reproduction process. A lens switching unit of a pickup unit is provided.
Switches the optical system corresponding to two or more types of different disks. The photoelectric conversion output detected by the pickup is input to the demodulators 23 and 24, and one of the demodulated outputs is taken out via the switch 25. The state detector 34 detects a mechanical lens setting state of the lens switching unit 21b and provides the same to the system control unit 32. Therefore, at the time of power-off recovery or reset, the system control unit 32 can use the detection result of the immediately preceding disc type to set the demodulator and quickly shift to an appropriate reproduction process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc reproducing apparatus, and more particularly to a disc reproducing apparatus capable of setting optimum reproducing characteristics to a plurality of different types of optical discs even in a recent situation. It was done.

[0002]

2. Description of the Related Art Conventionally, compact disks (CD) dedicated to music and laser disks (LD) in which video signals are digitized and recorded have been developed as optical disks. In recent years, CD-ROMs have been widely used as external storage media for computers. This CD-RO
A CD-ROM drive is used to read M recorded information. CD-ROM and host computer
Data is exchanged via the interface. This interface includes SCSI and ATA
What is called a PI is commonly used.

On the other hand, there has been proposed a DVD-ROM having a capacity approximately seven times that of the above-mentioned CD or CD-ROM.
This disc has the same radius (120 m) as the CD.
m), but the video data, audio data,
Sub-video data (for example, subtitle data) is compressed and recorded at a high density, and multiple types of audio and subtitles are recorded in different languages. A system has been developed that can freely select and play subtitles in a desired language. This kind of optical disc is DV
D (digital versatile disc).

A DVD-ROM drive is used to read the recorded information on the DVD-ROM. The DVD-ROM has a different physical format from the CD-ROM in order to increase the recording capacity.

The main difference is that the thickness of the substrate is 1.
2mm, DVD 0.6mm, track pitch is CD
Is 1.6 microns and DVD is 0.74 microns. The biggest difference is that the signal modulation and correction formats are different.

A reproducing apparatus for reproducing such an optical disk is recorded by rotating a servo unit for controlling the rotation of the disk or by irradiating a recording surface of the disk with a laser beam and detecting light reflected therefrom. An optical pickup device for reading the modulated signal is provided. The modulated signal output from the optical pickup device is input to a waveform equalization circuit, where the waveform is equalized. Next, the waveform-equalized signal is guided to the demodulation circuit. Further, the above-mentioned pickup device is provided with a focus servo system and a tracking servo system.

[0007]

In a conventional optical disk reproducing apparatus, a reproducing apparatus corresponding to the above-described optical disk has been independently developed, so that the demodulation circuit and the optical system have fixed characteristics in each apparatus. . This is because (A) it is assumed that the optical disc and the reproducing apparatus for reproducing the optical disc have a one-to-one correspondence. Also, (B) the bit clock of the modulation signal recorded on the optical disc is an ideal one that conforms to the standard, and the reproducing apparatus is also assumed to perform reproduction conforming to the standard of the optical disc. .

However, when there are different types of optical discs as described above, the user desires a reproducing apparatus capable of reproducing various kinds of discs by one unit. Therefore, in order to realize a reproducing apparatus capable of reproducing various kinds of disks, it is determined what type of optical disk is currently mounted, and the signal processing characteristics (demodulation circuit) are determined in accordance with the disk type. It is necessary to switch, and also in a servo system or an optical system, it is necessary to switch to a characteristic suitable for the disk type.

In the case of a disk reproducing apparatus capable of adaptively reproducing a plurality of different types of disks as described above, a "disk type detection function" is provided in comparison with a conventional disk reproducing apparatus. A new function called “reproduction characteristic switching function” is required.

Therefore, according to the present invention, after the processing by the "disc type detecting function" and the "reproduction characteristic switching function" is realized, the power is further cut off or the apparatus is reset. It is an object of the present invention to provide a disk reproducing apparatus capable of effectively utilizing the processing results of the detection function and the switching function in consideration of a countermeasure in the case of the above.

It is a further object of the present invention to provide a disk reproducing apparatus in which state storage means is inexpensively formed by effectively utilizing a member in which the previously used state is mechanically held.

[0012]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a disk loading portion capable of replacing two or more types of disks of different formats, and a disk loading portion loaded in the disk loading portion. Reading means for reading a recording signal recorded on a disk; demodulating means provided corresponding to each of the formats for demodulating a signal from the reading means; and reproducing data loaded on the disk loading section. Storage means for storing information about the format of the disk in, when the power is restored or the reset of the device is released, using the information about the format held in the storage means,
At least a reproduction state reproducing means for setting a demodulation processing state by the demodulation means so as to correspond to the format and obtaining a reproduction operation of the apparatus.

According to the present invention, the reading means has two or more optical systems having different aperture ratios (NA) corresponding to the format, and the storage means stores a selection state of the optical system during the reproduction. The reproduction state reproducing means also reproduces the selected state of the optical system during the reproduction using the information stored in the storage means when the power is restored or the reset of the device is released. Is what you do.

Further, the present invention is a system in which the two or more optical systems having different aperture ratios (NA) mechanically switch two or more lenses. Further, in the present invention, the optical systems having two or more different aperture ratios (NA) may be a system in which two or more apertures are switched.

In the present invention, the two or more optical systems having different aperture ratios (NA) are of a type in which the positions of two or more lenses are mechanically switched, and the positions of the two or more lenses in this optical system are changed. Further provided is a lens position detecting means for detecting, wherein the storing means stores mechanical information of the lens as stored information as state information of the optical system during the reproduction, and the lens position detecting means stores the stored information. It functions as reading means.

Still further, in the present invention, the two or more optical systems having different aperture ratios (NA) are of a type in which the aperture mechanism of the lens is mechanically switched, and detection means for detecting the state of the aperture mechanism is further provided. The storage means, as the state information of the optical system during the reproduction,
The mechanical state of the aperture mechanism may be stored information, and the detecting unit may be a stored information reading unit.

Further, in the present invention, the reading means selectively connects a laser light emitting means for reading information on the disk and two or more lenses having different aperture ratios (NA) to a path of an irradiation beam of the laser light emitting means. Switch to and place
Lens switching means capable of changing the intensity of the irradiation beam, direction changing means for changing the direction of a part of the irradiation beam depending on the switching state of the lens switching means, and part of the irradiation beam from the direction changing means Light detecting means for detecting the presence or absence of the light, and the storage means performs the operation itself of changing the direction of a part of the irradiation beam by the direction changing means moving in accordance with a switching state of the lens switching means. It is stored information.

In the present invention, a part of the irradiation beam is
The beam is in a direction approximately perpendicular to the track direction of the disk. Further, in the present invention, a part of the irradiation beam is a beam when a lens having a small aperture ratio (NA) is selected.

In the present invention, the reading means comprises:
Laser emission means for reading information on the disc;
An actuator capable of selectively arranging two or more lenses having different aperture ratios (NA) on a path of an irradiation beam of the laser light emitting means, and a switch capable of switching a movement position of the actuator by an electromagnetic force. Means, magnetic intensity detecting means, and intensity changing means for changing magnetic intensity acting on the magnetic intensity detecting means in response to switching of the position of the actuator by lens switching of the switching means, The detection signal of the magnetic intensity detection means during reproduction is
This is used as a determination signal of the lens switching state. According to the present invention, a plurality of disks having different formats are exchanged by an automatic exchange mechanism capable of detecting the exchange.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a DVD-ROM drive as a typical example of a device to which the present invention is applied.
The parts related to the present invention are extracted and shown.

The rotation of the optical disk 11 is controlled by a disk motor 12. An optical pickup device 21 is controlled to move in the radial direction of the disk by a feed motor (not shown). The optical pickup device 21 includes a laser emitter 21a (having a laser wavelength of 650 nm or 6 nm).
35 nm). The laser light emitter 21a irradiates a laser beam, and the irradiating beam is emitted through the objective lens to the optical disc 11
A beam spot is formed on the information track. The reflected light of this beam spot is guided by the half mirror and guided to the photodetector 22. The high-frequency signal which is the photoelectric conversion output of the photodetector 22 is supplied to the demodulator 23 and the demodulator 24. These demodulators 23 and 24 include a waveform equalizer, a data slicer, a data extraction unit, a demodulation unit, an error correction unit,
A sync separator for separating the synchronization signal is included.

The demodulator 23 is a demodulator corresponding to the DVD format, and the demodulator 24 is a demodulator corresponding to the CD format. The demodulated outputs of the demodulators 23 and 24 are
Either one is selected by the switch 25 and supplied to the host interface 26. The host interface 26 is connected to a host computer, and can send data to the host computer and receive commands from the host computer. The host computer can give a reset command or frequently give a reset release command to the DVD drive as necessary or unnecessary for data.

When a reset command arrives, the command is supplied to a system reset generator 31. The system reset generator 31 outputs a reset signal of each unit in response to the reset command, and also supplies a reset signal to a system control unit 32 that controls the entire DVD drive.

When a reset signal is input, the system control unit 32 uses the data in the state information memory to set the characteristics and selection of each unit. For example, the lens switching unit 21b in the pickup device 21 is controlled via the drive circuit 33, and unless the disk is replaced, the lens switching unit 21b is set to the same state as the state used during the reproduction before the reset.

Switching of the lens means switching of the numerical aperture (NA), that is, switching of the optical system, and will be described later. For DVD-ROM drives, DV
Both D and CD discs must be playable. For this purpose, for example, NA = 0.6 (DV) as an optical system corresponding to the track pitch.
D), switching of NA = 0.38 (CD) is required.

As a mechanism for switching the optical system, two lenses are prepared, and one of them is mechanically switched so that one of them is located in the path of the laser beam. Is mechanically switched by a shutter plate.

The selected state of the NA of the optical system is detected by the state detector 34, and the state detection signal is given to the system control unit 32. Further, the system control unit 32 controls the switching unit 25 so that the DVD demodulator 2
3 or the output of the demodulator for CD 24 can be selected.

FIG. 2A shows a specific configuration example of the above-described lens switching section 21b, and FIG. 2B shows the appearance of a lens holder. Lens switching unit 21b
As will be described later, this system is designed to have a function as a state storage unit.

A lens holder 75 is substantially coaxially rotatable inside a bottomed cylindrical lens holder support 74.
In addition, they are arranged so as to float freely. Lens holder support 7
An opening 76 for allowing a laser beam to pass therethrough is formed at the bottom of 4. A shaft 77 is provided at the center of the bottom of the lens holder support 75, and a substantially cylindrical lens holder 75 is supported by the shaft 77.

The lens holder 75 is provided on its upper surface with objective lenses 78 and 79 having different aperture ratios (NA). The centers of the objective lenses 78 and 79 are selected at positions different from the axis 77 by, for example, 90 degrees.

Next, permanent magnets 81 and 82 are disposed inside the cylinder of the lens holder support 74 at opposing positions. The line connecting the permanent magnets 81 and 82 and the central axis 77
Above, permanent magnets 83 and 84 are provided on a line intersecting at 90 degrees. Further, coils 91 to 94 facing these permanent magnets 81 to 84 are provided on the side surface of the lens holder 75.

FIG. 3 shows the relationship between the permanent magnets 81 to 84 and the coils 91 to 94. Now, depending on the rotation position of the lens holder, as shown in FIG.
It is assumed that coils 91 to 94 face 4. The magnetic poles of the permanent magnets 81 and 82 are arranged with NS in the rotational direction as shown, and the magnetic poles of the permanent magnets 83 and 84 are arranged with NS in the axial direction as shown. Further, the winding shape of each of the coils 91 to 94 is a rectangular shape similar to the outer shape of the permanent magnet. The coils 91 and 92 are electrically connected in series, and the coils 93 and 94 are electrically connected in series.

Now, when lens switching is performed, the following control is executed. That is, in the state as shown in FIG. 3A, when a current in the positive direction is supplied to the coils 91 and 92 as shown by an arrow P0 at a time t1 in FIG. Due to the interaction of the magnetic fields, a force FR in the rotation direction is generated in the coils 91 and 92, and serves as a force for rotating the lens holder (time t1 to t2). When the lens holder starts rotating, the coil portions 9 of the coils 91 and 92 are rotated.
At time t2 when 1b and 92b face the S poles of the permanent magnets 81 and 82, when a current in the opposite direction is applied to the coil, a force FR is generated which retreats the coils 81 and 82 from the permanent magnets 81 and 82, respectively. Then, the coils 91 and 92 move to the positions of the coils 93 and 94 shown. Also, the coils 93 and 94
Moves to the positions of the coils 92 and 91 in the figure. When returning to the original state, the coils 93, 9
By supplying a current reverse to that described above, the state shown in FIG. That is, the principle of the motor is used.

Further, the relationship between the permanent magnets 81 to 84 and the coils 91 to 94 also functions as a focus control drive mechanism and a tracking control drive mechanism. Now, it is assumed that they are arranged in the state of FIG.

As described above, the coil 9 is moved in the state shown in FIG.
When a current is supplied to the lens holders 1 and 92, a starting force in the rotation direction can be applied to the lens holder 75. If the control is performed minutely, the objective lens 78 or 79 in use can be finely controlled in the rotational direction (arrows X1-X2 in the drawing). This is to gain tracking control.

Next, when a very small current is supplied to the coils 93 and 94 in the state shown in the figure, the lens holder 75 is moved up and down, that is, in the axial direction of the lens (indicated by arrows Z1 and Z2 in FIG. ) Direction control. Therefore, in the state shown in the figure (for example, a state in which the lens 79 is used), a tracking control signal is supplied to the coils 91 and 92, and a focus control signal is supplied to the coils 93 and 94.

When the lens is switched (the state where the lens 78 is used), the coils 91 and 92 are
Is supplied with a focus control signal, and the coils 93 and 94 are supplied with a tracking control signal.

Looking at the average value of the focus control signal and the tracking control signal, the focus control signal usually has a larger current value. The lens switching unit 21b further includes an objective lens 78 (for a DVD having a large numerical aperture).
In order to detect which one of the objective lenses 79 (small numerical aperture and for CD) is in use, a use lens detection means is provided.

FIG. 4 shows an example of the detecting means. FIG. 4A shows a case where the use state of the objective lens 79 has been switched, and FIG. 4B shows a case where the use state of the objective lens 78 has been switched. A reflecting member 1 that reflects a part of the laser light on the outer peripheral side in a direction of about 90 degrees when the objective lens 79 is in use in a part of the lens holder 75.
00 is provided. The laser light reflected by the reflecting member 100 is detected by, for example, the state detector 34 provided on the lens holder support 74. However, when the objective lens 78 is in use, the reflecting member 100 that reflects a part of the laser beam does not exist around the objective lens 78.
The state detector 34 does not sense light. The detection output of the state detector 34 is supplied to the system control unit 32 as shown in FIG.

Thus, the system controller 32 can determine which objective lens is currently in use by judging the output of the state detector 34. The operation of the system configured as described above will be described step by step.

(Operation for Checking the State of Objective Lens) It is assumed that an objective lens for CD is set as an objective lens of the optical system. Here, it is assumed that the user loads a DVD disk via the automatic disk loading mechanism. The automatic disc loading mechanism is provided with an electric detector indicating the operating state of the automatic disc loading mechanism, and information of this detector is also supplied to the system control unit 32.

The system controller 32 detects that a disk has been loaded. Then, the system control unit 32 moves the pickup drive motor (not shown) to a predetermined position, and sends the laser
Turn on a. The laser light is the CD set in the past.
The light beam is converted into a predetermined light beam by the objective lens, and is irradiated on the disk 11.

When the objective lens 79 for CD is set, as described with reference to FIG. 4, a part of the laser beam is reflected in the direction of about 90 degrees by the reflection member 100 functioning as the state storage means. The state is detected by the state detector 34.
As a result, a signal b indicating that the CD objective lens 79 is in use is obtained from the state detector 34. A part of the unused laser light is reflected in a direction of about 90 degrees, which is perpendicular to the track direction. In this way, even if the tracking operation is performed, the range of change in the trajectory of the reflected light can be reduced,
This is because the light receiving area of the detector 34 can be small.

(Setting operation of demodulator) System control unit 32
Can confirm that the objective lens 79 for CD has been set by the above signal b, so the laser light emitter 21a is turned off once, and then the switch 25 is controlled by the signal c to Of the demodulator 24 is selected.

(Read Operation) Next, a CD read operation is performed. The system control unit 32 turns on the laser light emitter 21a, executes a predetermined pickup servo, and reads a disk signal. In this case, the photoelectric conversion output (high-frequency signal) from the photodetector 22 is subjected to demodulation processing by the demodulator 24 for CD. However, since the loaded disk is a DVD, the error correction circuit can often determine that the error cannot be corrected. The system control unit 32 receives the error correction impossible determination information, and determines that the currently loaded disc cannot be normally reproduced.

(Switching Operation of Objective Lens) The system control unit 32 controls the drive circuit 33 by the control signal d. The drive circuit 33 controls the lens switching unit 21b according to the control signal e.
Is switched to the use state of the DVD objective lens 78 as described with reference to FIG. At this time, no reflected light enters the state detector 34 as described with reference to FIG. The output of the state detector 34 at this time is grasped by the system control unit 32, and it is recognized that the use state of the DVD objective lens 78 has been switched.

Next, since the system control unit 32 recognizes that the switching to the DVD objective lens 78 has been performed, the system control unit 32 controls the switching unit 25 by the control signal c, and the DVD demodulator 2
3 is switched to the output selection state. After this switch, the DV
The operation proceeds to the reading operation of D. In the case of this reading, since the matching of the optical disk, the optical system, and the demodulator has been obtained, normal data reading is realized. The output data of the demodulator 23 passes through the switch 25 and then is taken out via the interface 26 and sent to the host computer via the bus.

(Reset Command and Power-On) When the power is turned on or when the system is started, a reset command is given from the host computer via the interface 26. The reset command is given to a system reset generator 31 inside the playback device. System reset generator 3
1 supplies a system reset signal to a predetermined circuit of each unit in the playback device and also to a system control unit 32.
As a result, the entire playback device is in the initial setting state.

However, since the lens switching section 21b is mechanically held, it remains in the state before the reset command or power-off (corresponding to storing the state). The system control unit 32 checks the state of the objective lens in the pickup, sets the demodulation circuit, and performs the reading operation according to a predetermined sequence process from the initial setting state. In this case, the disk has not been replaced (DV
D), a normal data reading operation can be performed.

(Explanation of Advantages of Reproducing Apparatus) According to the above-described disc reproducing apparatus, in the first embodiment, the lens switching function originally provided (the state set before power-off and before reset remains). Is used effectively. Then, when a reproduction operation command, a power-on, and a reset command are issued, a read operation can be executed immediately without newly discriminating the disc.

In particular, when starting up the entire system, a reset command is frequently given from the host computer to the disk drive. At this time, if the processing for disc recognition is performed every time a command is issued, it takes a long time to start up the system, and the value of the product is inferior. In some systems using a host computer and disk drives, a number of disk drives may be managed and operated in association with the host computer.
In such a case, it is desired that the startup of the disk drive be as fast as possible. In such a case,
According to the apparatus of the present invention, it is possible to immediately shift to the information reading operation as long as the disk is not replaced with a disk of a different type and a disk of the type previously used.

In a system operating in this manner, it is not necessary to perform a disk determination operation upon receiving a reset command at system startup or every time the power is turned on. In this case, the chances of destroying data can be reduced.

In the above description, the number of lens systems is described as two, but the number is not limited to this and may be many. In addition, although one type of laser light emitter is shown, a plurality of types may be present and switched.

In the above description, the switching of the optical system is
Although the two lenses were selectively switched to the use state,
The switching of the optical system may be a method of mechanically switching the stop by sharing the lens. In this case, the mechanical state of the aperture indicates the storage information and the selection information.

In the above description, the disk switching unit 21a, which represents the disk to be used in a mechanical state, was used as the disk type storage means. However, the disk type storage means can be realized by a memory that is not controlled by system reset or power off, or a memory with a backup power supply or a flash memory when the system power is off.

Therefore, a new state information memory 32a may be provided in the system control unit 32, and the system may be set at power-on or reset based on the contents of this memory. Also, when playback is running normally,
The status information of the system is stored in the status information memory 32a.

When a disc is loaded in the reproducing apparatus for the first time or when the disc is replaced, it is necessary to determine the type of the disc. In such a case, an electric signal from the automatic disk loading mechanism may be stored in the state information memory 32a. If there is a disk exchange when there is a start command, a disk discriminating operation may be performed.

Further, the magnetic sensor may be configured as a state detecting and storing means using, for example, a Hall element. That is, the magnetic flux collecting plate is inserted and removed between the permanent magnet and the magnetic sensor according to the switching of the lens.
As a result, the magnetic sensor detects non-magnetism of the permanent magnet,
Detection can be performed. For example, as shown in FIG. 5, the magnetic sensor 121 is arranged in front of the permanent magnet 82 at an interval. The magnetic sensor 121 is mounted on the lens holder support 7.
4 is attached to the tip of an arm attached to the edge. On the other hand, the magnetic flux collecting plate 122 is
Is provided. Then, when the lens is switched and the objective lens 78 is used, the magnetic flux collecting plate 122 moves between the magnetic sensor 121 and the permanent magnet 82. In this way, by monitoring the output of the magnetic sensor 121, it is possible to easily detect which objective lens is currently in the set state.

Further, FIG. 6 shows that the aperture mechanism is used for CD reproduction,
This is a means for switching the aperture ratio (NA) which is switched according to VD reproduction. The aperture plate 130 is moved magnetically or by a motor in the direction of the arrow to open the apertures 131, 13 thereof.
Either one can be placed in the beam path of the laser emitter 12a. Therefore, if the state of the diaphragm plate 130 is detected by, for example, a photo sensor, it is possible to know which aperture ratio is currently set.

[0060]

As described above, according to the present invention,
When the power supply is restored or the device is reset, the detection result of the disk type can be effectively used, and the process can be promptly shifted to the next reproduction process. Thus, the reliability of the device can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is an example of a state detection and storage unit according to the present invention, showing an example of a switching unit of an optical system.

FIG. 3 is a diagram shown for explaining the operation of a switching unit of the optical system shown in FIG. 2;

FIG. 4 is a diagram specifically showing a state detection and storage unit of a switching unit of the optical system.

FIG. 5 is another example of the state detection and storage unit according to the present invention, showing an example of a switching unit of an optical system.

FIG. 6 is a diagram showing still another example of the state detection and storage unit according to the present invention, showing an example of a switching unit of an optical system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Optical disk 12 ... Disk motor 21 ... Optical pickup device 21a ... Laser light emitting device 21b ... Lens switching part 22 ... Photodetector 23, 24 ... Demodulator 25 ... Switching device 26 ... Host interface 31 ... System reset generator 32 ... System Control part 33 ... Drive circuit 34 ... State detector.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location G11B 7/135 G11B 7/135 Z

Claims (10)

[Claims] 1. A disc loading section that can be loaded by exchanging two or more types of discs of different formats, reading means for reading a recording signal recorded on a disc loaded in the disc loading section, A demodulating means provided for each of the formats, for demodulating a signal from the reading means, a storage means for storing information relating to the format of the disc being loaded in the disc loading section and being reproduced, When the recovery of the device or the reset of the device is released, at least the demodulation processing state by the demodulation unit is set to correspond to the format by using the information on the format held in the storage unit. Disc reproducing apparatus provided with reproducing state reproducing means for obtaining a reproducing operation of the apparatus. . 2. The reading means has an optical system having two or more different aperture ratios (NA) corresponding to the format,
The storage unit stores a selection state of the optical system during the reproduction, and the reproduction state reproduction unit stores the state of the storage unit when the power is restored or the reset of the device is released. 2. The disc reproducing apparatus according to claim 1, wherein a selected state of the optical system during the reproduction is also reproduced by using information. 3. The disk reproducing apparatus according to claim 2, wherein said two or more optical systems having different aperture ratios (NA) are of a type in which two or more lenses are mechanically switched. 4. The disk reproducing apparatus according to claim 2, wherein the two or more optical systems having different aperture ratios (NA) are of a type that switches between two or more apertures. 5. An optical system having two or more different aperture ratios (NA) is a system for mechanically switching the positions of two or more lenses, and a lens for detecting the positions of the two or more lenses in the optical system. Position detection means is further provided, wherein the storage means uses the mechanical position of the lens as storage information as a selection state of the optical system during the reproduction, and the lens position detection means is a storage information reading means. 2. The disk reproducing apparatus according to claim 1, wherein: 6. An optical system having two or more different aperture ratios (NA) is a system for mechanically switching a diaphragm mechanism of a lens, and further comprising a detecting means for detecting a state of the diaphragm mechanism. 2. The storage unit according to claim 1, wherein the storage unit stores a mechanical state of the diaphragm mechanism as storage information as a selection state of the optical system during the reproduction, and the detection unit is a storage information reading unit. Disc playback device. 7. The reading means comprises: a laser light emitting means for reading information on the disk; and selectively switching at least two lenses having different aperture ratios (NA) to a path of an irradiation beam of the laser light emitting means. Lens switching means arranged to change the intensity of the irradiation beam, direction changing means for changing a direction of a part of the irradiation beam depending on a switching state of the lens switching means, and the irradiation beam from the direction changing means Light detecting means for detecting the presence or absence of a part of the irradiation beam, wherein the storage means changes the direction of a part of the irradiation beam by the direction changing means moving in accordance with a switching state of the lens switching means. 2. The disk reproducing apparatus according to claim 1, wherein the operation itself is stored information. 8. A disk reproducing apparatus according to claim 7, wherein a part of said irradiation beam is a beam in a direction approximately perpendicular to a track direction of said disk. 9. A method according to claim 1, wherein a part of said irradiation beam is said to have an aperture ratio (N
8. The disk reproducing apparatus according to claim 7, wherein the beam is a beam when a lens having a smaller size of A) is selected. 10. A reading means, comprising: a laser light emitting means for reading information on the disc; and at least two lenses having different aperture ratios (NA) selectively switching to a path of an irradiation beam of the laser light emitting means. An actuator that can be arranged; a switching unit that can switch the movement position of the actuator by an electromagnetic force; a magnetic intensity detection unit; and a lens that is switched by the switching unit in response to the switching of the position of the actuator. And an intensity changing means for changing a magnetic intensity acting on the magnetic intensity detecting means, wherein a detection signal of the magnetic intensity detecting means during the reproduction is a determination signal of a lens switching state. The disk reproducing apparatus according to claim 1.