JPH09270167A - Optical disk kind discriminating device and optical disk player device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely and rapidly discriminate a kind of an optical disk by using a focus servo and detecting a size of a fluctuation amount of a reflection light quantity when a luminous flux traverses a recording track on the signal recording surface of the optical disk. SOLUTION: A rotational operation mechanism holds and rotates an optical disk 101. An objective lens 22 focuses the luminous flux from light sources 16, 17 on the signal recording surface of the optical disk 101. A focus error detection means generates a focus error signal showing a distance between the converged point of the luminous flux by the objective lend 22 and the signal recording surface based on the state of the reflection luminous flux from the signal recording surface of the luminous flux. A focus servo means moves the objective lens 22 in the attaching/ detaching direction for the optical disk 101 based on the focus error signal, and places the converged point of the luminous flux by the objective lens 22 on the signal recording surface. A reflection light quantity detection means 23 detects the light quantity of the reflection luminous flux from the signal recording surface of the luminous flux. Then, a discrimination means detects the fluctuation amount of the light quantity of the reflection luminous flux based on the detection result.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technical field of an optical disc type discriminating device for discriminating a substrate thickness or the like of an optical disc which is an optical recording medium, and an optical disc player device for recording or reproducing information signals on the optical disc. Belong to

[0002]

2. Description of the Related Art Heretofore, an optical disc has been proposed as an optical recording medium serving as a recording medium for information signals, and an optical disc player device for recording and reproducing information signals on the optical disc has been proposed.

The above-mentioned optical disk comprises a substrate made of a transparent material such as polycarbonate, and a signal recording layer deposited on one main surface of the substrate.

The optical disc player device is provided with a rotating operation mechanism for holding and rotating the optical disc and an optical pickup device for writing or reading an information signal to or from the optical disc.

The above optical pickup device includes a semiconductor laser as a light source, a grating (diffraction grating) on which a light beam emitted from the semiconductor laser is incident, a beam splitter, and an objective lens on which the light beam passing through the beam splitter is incident. Also, it has a photodetector which is a photodetector.

The above grating splits the incident light beam into three light beams. The reason for dividing the light beam in this manner is to detect a tracking signal by the so-called three-beam method.

The beam splitter is made of an optical material as a plane-parallel plate, and the main surface portion serving as a reflecting surface is arranged so as to be inclined by 45 ° with respect to the optical axis of the light beam from the semiconductor laser. There is.

Then, the light flux incident on the objective lens is condensed and irradiated on the signal recording surface of the optical disc by the objective lens. At this time, this light flux is irradiated onto the optical disc from the substrate side of the optical disc, passes through the substrate, and is condensed on the signal recording surface which is the surface portion of the signal recording layer. This objective lens is 2
By being supported and moved by the shaft actuator, the light flux is always focused on the recording track on which the information signal on the signal recording surface is recorded.

In the optical disc, the light flux that has passed through the objective lens is condensed and irradiated, so that the information signal is written or read at the position where the light flux is irradiated.

The light flux radiated on the signal recording surface has a light quantity, depending on the information signal recorded on the signal recording surface,
Alternatively, the polarization direction is modulated, reflected by the signal recording surface, and returned to the objective lens.

The reflected light beam reflected by the signal recording surface reaches the beam splitter through the objective lens. The reflected light beam is branched by the beam splitter into a path returning to the semiconductor laser, and is directed to the photodetector.

The photodetector is a light receiving element such as a photodiode, which receives the light beam passing through the beam splitter and converts it into an electric signal. The information signal recorded on the optical recording medium is reproduced based on the electric signal output from the photodetector.

[0013]

By the way, in an optical disc such as the above-mentioned optical disc, since it is used as an auxiliary storage device for a computer and as a recording medium for audio and image signals, the recording density of the information signal is reduced. Higher density is being promoted.

In order to write and read information signals to and from the optical disc having a high recording density, the objective lens having a larger numerical aperture (NA) is formed on the optical recording medium. It is necessary to reduce the beam spot formed by condensing the light flux.

However, when the numerical aperture of the objective lens becomes large, the tolerance of the tilt of the optical disc, the thickness unevenness of the substrate of the optical disc, and the defocus of the light flux on the optical disc decreases. Therefore, it becomes difficult to write and read the information signal to and from this optical disc.

For example, when an inclination (skew) with respect to the optical axis of the objective lens of the optical disc occurs, wavefront aberration occurs in the light beam focused on the signal recording surface, and an electric signal (RF) output from the photodetector is generated. Output) is affected.

This wavefront aberration is dominated by a third-order coma aberration which is generated in proportion to the cube of the numerical aperture of the objective lens and the cube of the tilt angle (skew angle) of the optical recording medium. Therefore, the permissible value for the tilt of the optical recording medium is inversely proportional to the cube of the numerical aperture of the objective lens, that is, it decreases as the numerical aperture increases.

Thickness 1.2 mm, diameter 80 mm or 12
In an optical disc (such as a so-called “compact disc” (trade name)) which is configured to have a substrate formed of a 0 mm disk-shaped polycarbonate and is widely used at present, the tilt angle is ± 0. A tilt of 5 ° to ± 1 ° may occur.

In such an optical disc, the above-mentioned wavefront aberration occurs in the light beam irradiated on the optical disc, the beam spot on the optical disc has an asymmetrical shape, and intersymbol interference remarkably occurs, so that accurate signal reproduction is performed. Will be difficult.

The amount of such third-order coma aberration is proportional to the thickness of the substrate of the optical disc. Therefore, by reducing the thickness of the substrate (for example, 0.6 mm),
Third-order coma aberration can be halved. In the case of reducing the coma aberration in this way, a plurality of types of optical discs having a substrate having a thickness of 1.2 mm and a substrate having a thickness of 0.6 mm are mixed as the optical disc. Will be used.

By the way, when a plane parallel plate having a thickness t is inserted in the optical path of the convergent light beam condensed by the objective lens, t is associated with this thickness t and the numerical aperture NA of the objective lens. Spherical aberration proportional to × (NA) ⁴ occurs.

The objective lens is designed so that this spherical aberration is corrected. That is, since the amount of spherical aberration that occurs is different when the thickness of the substrate is different, the objective lens is designed as being adapted to the predetermined thickness of the substrate.

Then, using an objective lens designed and adapted to an optical disc having a substrate of, for example, 0.6 mm, an optical disc having a substrate of 1.2 mm (for example, "compact disc", added. Type optical disc, magneto-optical disc), the difference in the thickness of these substrates (0.6 mm) is the thickness of the substrate that can be handled by the optical pickup device. It means that the allowable range of the error of is greatly exceeded. In this case, the objective lens cannot correct the spherical aberration generated due to the difference in the thickness of the substrate, and good recording and reproducing of the information signal cannot be performed.

Therefore, in the above optical pickup device, it is necessary to change the numerical aperture of the objective lens according to the thickness of the substrate of the optical disc by using a mechanical diaphragm or the like.

However, if the type of the optical disc loaded in the optical disc player device cannot be determined, control of the optical pickup device such as the operation of the diaphragm cannot be performed accurately and quickly. It is conceivable that the user of the optical disk player device will judge the type of the optical disk mounted and switch the aperture by manual operation, but erroneous operation is likely to occur, and quick recording / reproducing operation cannot be performed.

Therefore, the present invention has been proposed in view of the above-mentioned circumstances, and an optical disc type discriminating apparatus and a disc type discriminating device capable of discriminating accurately and speedily the type of an optical disc such as a substrate having a different thickness. It is equipped with this optical disc type discriminating device and is suitable for plural types of optical discs.
Another object of the present invention is to solve the problem of providing an optical disc player device capable of favorably recording and reproducing information signals quickly.

[0027]

In order to solve the above problems, an optical disc type discriminating apparatus according to the present invention includes a rotation operation mechanism for holding and rotating an optical disc which is a recording medium for information signals, a light source, and a light source. An objective lens for condensing the light beam emitted from the light source on the signal recording surface of the optical disc being rotated by the rotation operation mechanism, and the objective based on the state of the light beam reflected from the signal recording surface of the light beam. Focus error detection means for generating a focus error signal indicating a distance between the focal point of the light flux by the lens and the signal recording surface, and the objective lens in the direction of approaching and separating from the optical disc based on the focus error signal. Focus servo means for moving the light beam to position the focal point of the light beam on the signal recording surface by the objective lens, and a light beam reflected from the signal recording surface of the light beam. The apparatus includes: a reflected light amount detecting means for detecting a light amount; and a discriminating means for detecting a variation amount of the light amount of the reflected light flux based on a detection result by the reflected light amount detecting means, wherein the discriminating means is characterized in that the rotation operation mechanism is the optical disc The rotation amount of the reflected light flux is large when the light flux traverses a recording track on the signal recording surface of the optical disc in a state in which the light beam is held and rotated, and the focus servo means is operating. Based on this, the disc type is determined.

Further, the disc player device according to the present invention rotates the optical disc, which is a recording medium of the information signal, with a rotation operation mechanism for rotating and operating the light source and the light beam emitted from the light source by the rotation operation mechanism. An optical pickup device having an objective lens for converging on a signal recording surface of an optical disc being operated, and an optical pickup device having a reflected light amount detecting means for detecting a light amount of the light beam of the light beam reflected from the signal recording surface, Focus error detection means for generating a focus error signal indicating the distance between the focal point of the light beam by the objective lens and the signal recording surface based on the state of the light beam reflected from the signal recording surface of the light beam, Based on the focus error signal, the objective lens is moved toward and away from the optical disc to focus the light beam on the objective lens. The focus servo means positioned on the signal recording surface and the detection result by the reflected light amount detection means in a state in which the rotation operation mechanism holds the optical disk to rotate and the focus servo means is operating. The amount of variation in the amount of light of the reflected light flux is detected based on the amount of variation of the amount of light in the reflected light flux when the light flux traverses a recording track on the signal recording surface of the optical disc, and the disc type is determined. And a control means for executing an operation according to the type of the optical disc held by the rotation operation mechanism, which is discriminated by the discriminating means.

[0029]

Embodiments of the present invention will be described below with reference to the drawings.

In this embodiment, an optical disc type discriminating apparatus according to the present invention is provided with a first type optical disc whose transparent substrate has a thickness of 0.6 mm and a transparent substrate having a thickness of 1.2 m.
It is configured as a device for discriminating the optical disc of the second type which is m.

Further, in this embodiment, the optical disk player device according to the present invention is applied to each of the above optical disks.
It is configured as a device capable of recording and reproducing information signals.

This optical disk player device writes or reads information signals to or from a rotary operation mechanism (spindle mechanism) for holding and rotating the above optical disk and an optical disk rotationally operated by this rotary operation mechanism. And an optical pickup device. The disc type determination device is configured to include the optical pickup device in the optical disc player device.

Further, in this optical disc player device, the optical pickup device is arranged so as to face the optical disc held by the rotating operation mechanism, and can be moved over the inner and outer peripheries of the optical disc. .

As shown in FIGS. 6 and 8, the optical disc of the first type has a thickness T ₁ (0.6 mm) and a diameter of 12 mm.
The transparent substrate 103 is made of 0 mm disc-shaped polycarbonate, and the signal recording layer (or the reflection layer) 104 is formed on one main surface of the transparent substrate 103. This first type of optical disc 101
The two optical discs 101 of the first type are bonded to each other on the signal recording layer sides to form a disc body (so-called double-sided disc) having a thickness of 1.2 mm.

The optical disc 101 of the first type writes an information signal through a laser beam having a first wavelength of 635 nm or 650 nm through an objective lens having a numerical aperture (NA) of 0.6. And read out.

Such a first type optical disc 101
For example, a so-called “digital video disc (DVD)” (trademark name) has been proposed as a device corresponding to the above.

As shown in FIG. 6, the second type optical disc 102 has a thickness T ₂ (1.2 mm) and a diameter of 80 m.
The transparent substrate is formed of a disc-shaped polycarbonate of m or 120 mm, and the signal recording layer (or the reflection layer) is formed on one main surface of the transparent substrate.

In the second type optical disc 102, information signals are written and read by a laser beam having a wavelength of 780 nm, which is the second wavelength, through an objective lens having a numerical aperture of 0.45. It is configured.

Such a second type of optical disc 102
For example, a so-called "compact disc (CD)" (trademark name) has been proposed as a device corresponding to the above.

In these discs 101 and 102, the surface portion of the signal recording layer 104 (or the back surface portion of the transparent substrate 103), that is, the signal recording layer (or reflective layer) 104 and the transparent substrate 103, Is the signal recording surface. In addition, these optical disks 10
In Nos. 1 and 102, information signals are recorded along the recording tracks formed on the signal recording surface. The recording track is formed on the signal recording surface in a spiral shape having a substantially concentric shape. The portion of the signal recording surface where the recording track is not formed is approximately 10
It is mirror-like with a reflectance close to 0%.

Further, these optical disks 101, 102
Has a chucking hole for positioning in the central portion, and the peripheral portion of the chucking hole is held by the rotation operation mechanism.

As shown in FIG. 6, the optical pickup device constituting the optical disc type discriminating device according to the present invention has a first semiconductor laser (LD1) as a first light source.
16 and a second semiconductor laser (LD
2) It has 17.

Each of the semiconductor lasers 16 and 17 emits a laser beam which is a linearly polarized coherent light beam. These laser beams are divergent beams. The wavelength of the light flux emitted by the first semiconductor laser 16 is 635 nm or 650 nm, which is the first wavelength. The wavelength of the light beam emitted by the second semiconductor laser 17 is 780 nm, which is the second wavelength.

The above laser beams are combined by a beam combining prism 18 and a grating (line grating) 19 is formed.
To reach the beam splitter 20. The beam synthesizing prism 18 has a semi-transmissive film portion, reflects the laser light flux from the first semiconductor laser 16 by the semi-transmissive film portion and deflects it at a right angle, and also from the second semiconductor laser 17. Of the first and second semiconductor lasers 1 by transmitting the laser light flux of
The light fluxes from 6 and 17 are combined.

The grating 19 divides the incident light flux into three light fluxes. The reason for dividing the light beam in this manner is to detect a tracking signal by the so-called three-beam method.

The beam splitter 20 is made of an optical material in the form of a parallel plate, and the main surface portion serving as a reflecting surface is arranged with an inclination angle of 45 ° with respect to the optical axis of the laser beam from the beam combining prism 18. ing. The beam splitter 20 reflects the laser light flux from each of the semiconductor lasers 16 and 17 by the main surface portion and deflects it at right angles.

The laser beam reflected by the beam splitter 20 passes through the diaphragm 21 and enters the objective lens 22. This objective lens 22 has a numerical aperture (NA) of 0.6. The diaphragm 21 is for variably adjusting the diameter of the light flux to be passed therethrough and changing the substantial numerical aperture of the objective lens 22.

In this optical pickup device, when the first semiconductor laser 16 is turned on and the wavelength of the laser beam incident on the objective lens 22 is the first wavelength (635 nm or 650 nm),
The diaphragm 21 is opened.

At this time, almost all of the laser beam emitted from the first semiconductor laser 16 passes through the diaphragm 21 and becomes the _first laser beam R ₁ . At this time, the numerical aperture of the objective lens 22 is 0.6.

Further, in this optical pickup device, when the wavelength of the laser light flux which is turned on by the second semiconductor laser 17 and is incident on the objective lens 22 is the second wavelength (780 nm), the aperture is stopped. 21 is
It is narrowed down.

At this time, the laser beam emitted from the second semiconductor laser 17 passes through the diaphragm 21 only in the portion near the optical axis and becomes the _second laser beam R ₂ . At this time, the substantial numerical aperture of the objective lens 22 is 0.
It is 45.

The laser light flux which has entered the objective lens 22 through the aperture 21 is the objective lens 22.
As a result, the signal recording surfaces of the optical discs 101 and 102 are condensed and irradiated. At this time, the laser light flux is applied to the optical discs 101 and 102 from the transparent substrate side of the optical discs 101 and 102, passes through the transparent substrates, and the signal recording surface that is the surface portion of the signal recording layer. Focused on top.

As shown in FIG. 8, the objective lens 22 is supported by a biaxial actuator 31 constituting a focus servo means via a lens frame, and the diaphragm 2
8 and the optical axis direction shown by the arrow P in FIG. 8 and the direction orthogonal to the optical axis, the laser beam 32 is always recorded on the recording track on which the information signal on the signal recording surface is recorded. To focus.

The objective lens 22 is the objective lens 2
It is designed so that when a plane-parallel plate having a thickness t is inserted in the optical path of the convergent light flux condensed by 2, spherical aberration generated in proportion to t × (NA) ⁴ is corrected. .
That is, the objective lens 22 has a substrate thickness of 0.6.
It is designed to be compatible with mm mm optical recording media.

In each of the optical discs 101 and 102, the laser light flux that has passed through the objective lens 22 is condensed and irradiated, so that an information signal can be written or read at the position where the laser light flux is irradiated. Be seen.

Further, the laser light flux irradiated on the signal recording surface is reflected by the signal recording surface after being modulated in the light amount or the polarization direction according to the information signal recorded on the signal recording surface. , And returns to the objective lens 22. Thus, the reflected light flux reflected on the signal recording surface has a smaller amount of light when reflected on the recording track than when reflected on a portion where the recording track is not present.

The optical pickup device has a photodetector 23 which serves as a reflected light quantity detecting means for detecting the quantity of the reflected light flux of the laser light fluxes R ₁ and R ₂ from the signal recording surface.

That is, the reflected light beam reflected by the signal recording surface reaches the beam splitter 20 through the objective lens 22. This reflected light flux is transmitted through the beam splitter 20, and is branched to the path returning to the beam combining prism 18, and is directed to the photodetector 23.

The photodetector 23 is a light receiving element such as a photodiode, receives the reflected light flux that has passed through the beam splitter 20, and converts the reflected light flux into an electric signal (RF output) of an output corresponding to the light quantity of the reflected light flux. An electric signal (RF output) output from the photo detector 23
Based on the above, the information signal recorded on each of the optical discs 101 and 102 is reproduced.

As shown in FIG. 7, the photodetector 23 has four light-receiving surface portions 24, 25, 26, 27 radially arranged around the optical axis. Then, the reflected light flux is converted into the photodetector 23.
The beam spots 28 formed on the light receiving surface of the first and second elliptical beam spots 29 and 30 correspond to the direction of the astigmatism caused by passing through the beam splitter 20. Become. The first and second elliptical beam spots 29 and 30 have major axis directions orthogonal to each other.

When the photodetection outputs from the four light receiving surface portions 24, 25, 26 and 27 of the photodetector 23 are a, b, c and d, the level RF of the RF output is RF = a + b + c + d. Then, Fe = (a + c)-(b + d) is a signal indicating the direction and amount of the astigmatism of the reflected light flux. This Fe is a focus error signal, which is calculated by the focus error detecting means. The focus error signal Fe is a signal that indicates the distance and direction between the focal point of the light beam by the objective lens 22 and the signal recording surface.

The biaxial actuator 16 that supports the objective lens 22 is driven based on the focus error signal Fe to move the objective lens 22 to move the focal point of the light beam by the objective lens 22. The focus servo operation for always positioning the signal recording surface is executed.

In this optical pickup device, when writing and reading an information signal to and from the optical disc 101 of the first type, the diaphragm 21 is opened and the first semiconductor laser 16 is opened.
Only the light is turned on, and the numerical aperture of the objective lens 22 is 0.
It becomes 6.

In this case, the condition for writing and reading the information signal to / from the optical disc 101 of the first type, that is, the numerical aperture of the objective lens 22 is 0.6 and the wavelength of the laser beam is 635 nm or 650 nm. This condition is satisfied, and it is possible to write and read information signals to and from the optical disc 101 of the first type.

In addition, in this optical pickup device, when writing and reading an information signal to and from the optical disc 102 of the second type, the diaphragm 2 is used.
1 is narrowed down and the second semiconductor laser 17
Only one of them is turned on, and the substantial numerical aperture of the objective lens 22 becomes 0.45.

At this time, the thickness t of the substrate is
And the numerical aperture (NA) of the objective lens 22,
That is, spherical aberration that occurs in proportion to t × (NA) ⁴ is suppressed because the numerical aperture is small, and good writing and reading of information signals with respect to the second type optical disc 102 is realized.

In the disc player device having the optical pickup device, the numerical aperture of the objective lens 22 is selected by selecting the first and second optical discs mounted on the rotary operation mechanism. Disc type discriminating apparatus discriminates which one of the optical discs 101 and 102 is the disc type, and the control means drives the diaphragm 21 according to the discrimination result and the first disc
And the second semiconductor lasers 16 and 17 are selectively turned on.

That is, the control means, when the loaded optical disc is the first disc 101,
When the diaphragm 21 is opened and the first semiconductor laser 16 is turned on, and the loaded optical disk is the optical disk 102 of the second type, the diaphragm 21 is narrowed and the second semiconductor laser 17 is used. Light up. As this control means, a control circuit for switching the semiconductor lasers 16 and 17 and supplying power can be used.

As shown in FIG. 5, the disc type discriminating apparatus has a discriminating circuit as discriminating means. This discriminating circuit detects the light flux reflected by the photodetector 23 in a state in which the rotation operation mechanism holds the optical disk for rotation operation and the focus servo means operates based on the focus error signal Fe. The variation amount of the light amount of the reflected light flux is detected based on the detection result of the light amount.

The discriminating circuit discriminates the type of the optical disc based on the variation amount of the light amount of the reflected luminous flux when the luminous flux traverses the recording track on the signal recording surface of the optical disc. .

When the focus servo means is operating based on the focus error signal Fe, the focal point of the light beam by the objective lens 22 is located on the signal recording surface. At this time, since the tracking servo that causes the converging point to follow the recording track is not operating, when the rotating operation mechanism rotates the optical disk, the converging point of the optical disk causes the converging point to change. A plurality of recording tracks are periodically crossed as the optical disc rotates.

As shown in FIG. 1, the RF output at this time is modulated according to the information signal recorded on the recording track when the converging point is located on the recording track, and The output level varies depending on whether or not the converging point is located on the recording track. The modulation in accordance with the information signal recorded on the recording track is extremely high frequency as compared with the fluctuation frequency of the output level depending on whether or not the condensing point is located on the recording track. Therefore, when the RF output is observed on the frequency axis corresponding to the fluctuation of the output level depending on whether or not the condensing point is located on the recording track, the fluctuation of the output level is
Appears on the bottom line of the output fluctuation range.

In the discriminating circuit, the RF output is input to the input terminal 1 and passed through the bottom hold circuit. The bottom hold circuit includes a first diode 2 having an output terminal connected to the input terminal 1, a first capacitor 4 having one end connected to an input terminal of the first diode 2, The first current source 3 supplies a current to the input terminal of the first diode 2. The other end of the first capacitor 4 is connected to the reference voltage VC.

In this bottom hold circuit, the output terminal side of the first diode 2 (the input terminal 1 side) is lower than the input terminal side of the first diode 2 (the first capacitor 4 side). Each time the potential is reached, the potential at this time is stored in the first capacitor 4 to perform bottom hold. Then, the potential stored in the first capacitor 4 is raised with a predetermined time constant by the current supplied from the first current source 3. By repeating such bottom hold and potential increase, the bottom line of the RF output is taken out.

The bottom hold signal extracted by the bottom hold circuit is supplied to the non-inverting input terminal of the first subtractor 5, and the DC (direct current component) of the next stage is passed through the first subtractor 5. Sent to the removal circuit. The inverting input terminal of the first subtractor 5 is connected to the output terminal of the first subtractor 5.

The DC removing circuit includes the first subtractor 5
Second capacitor 6 whose one end is connected to the output terminal of
And a resistor 7 having one end connected to the other end of the second capacitor 6. The other end of the resistor 7 is connected to the reference voltage VC.

In this DC removing circuit, the DC component of the signal input by the second capacitor 6 is removed, and the center of fluctuation of this signal is the reference voltage V.
Made as C.

The signal passed through the DC removing circuit is supplied to the non-inverting input terminal of the second subtractor 8 and is sent to the peak hold circuit of the next stage via the second subtractor 8. The inverting input terminal of the second subtractor 8 is connected to the output terminal of the second subtractor 8.

The peak hold circuit has a second diode 9 whose input end is connected to the output terminal of the second subtractor 8 and one end of which is connected to the output end of this second diode 9. It is composed of a third capacitor 11 and a second current source 10 that takes out a current from the output end of the second diode 9 and supplies it to the ground portion (ground portion). The other end of the third capacitor 11 is connected to the reference voltage VC.

In this peak hold circuit, the input terminal side of the second diode 9 (the second subtracter 8
Side) becomes higher than the output terminal side of the second diode 9 (the side of the third capacitor 11), the potential at this time is stored in the third capacitor 11, and the peak hold is achieved. Is done. Then, the potential stored in the third capacitor 11 is dropped with a predetermined time constant by the current supplied by the second current source 10. By repeating such peak hold and potential drop, the peak of the input signal is extracted.

The peak hold signal extracted by the peak hold circuit is supplied to the non-inverting input terminal of the third subtractor 12, and passes through this third subtractor 12.
It is sent to the comparator 13. The inverting input terminal of the third subtractor 12 is connected to the output terminal of the third subtractor 12.

The comparator 13 compares the peak hold signal output from the peak hold circuit with the voltage value of the discrimination voltage 14. The comparison result by the comparator 13 is output from the output terminal 15 as a determination output.

Assuming that the numerical aperture of the objective lens 22 is 0.45, the optical disc mounted on the rotary operation mechanism is the optical disc 1 of the second type.
In the case of No. 02, the spherical aberration generated in the light beam on the signal recording surface is small, and as shown in FIG. 1, the beam spot B ₁ formed by the light beam on the signal recording surface is small. At this time, the fluctuation of the RF output becomes large.
Therefore, at this time, as shown in FIG. 2, the bottom hold signal has a large signal amplitude b, the peak hold signal has a high level, and the determination signal has an "H" level. The control circuit determines that the loaded optical disk is the optical disk 102 of the second type because the determination signal is at the “H” level.

When the numerical aperture of the objective lens 22 is 0.45 and the optical disc mounted on the rotary operation mechanism is the optical disc 101 of the first type, on the signal recording surface. In the above, the spherical aberration generated in the light flux is large, and as shown in FIG. 3, the beam spot B ₂ formed by the light flux on the signal recording surface becomes large. At this time, the fluctuation of the RF output becomes small. Therefore, at this time, the bottom hold signal has a small signal amplitude a as shown in FIG. 4, the peak hold signal has a low level, and the determination signal has an "L" level. The control circuit determines that the loaded optical disc is the optical disc 101 of the first type because the determination signal is at the “L” level.

The numerical aperture of the objective lens 22 is set to 0.
When the optical disc mounted on the rotary operation mechanism is the optical disc 101 of the first type, the discriminating signal becomes “H” level, and the optical disc mounted on the rotary operation mechanism is set to “6”. In the case of the optical disc 102 of the second type, the discrimination signal becomes "L" level.

When the RF output is inverted and input to the discrimination circuit, the peak hold circuit is first passed instead of the bottom hold circuit in the first stage, and then DC removal is performed. , The peak output can be obtained by passing the peak hold.

[0087]

As described above, in the optical disc type discriminating apparatus according to the present invention, when the rotating operation mechanism holds the optical disc and rotates it, and the focus servo means is operating, The type of the optical disc is discriminated based on the magnitude of the variation of the reflected light amount of the light flux when the light flux focused and irradiated on the signal recording surface traverses the recording track on the signal recording surface.

Therefore, in this optical disc type discriminating apparatus, the type of the optical disc can be discriminated accurately and quickly only by operating the focus servo means.

Further, the disc player device according to the present invention is provided with the above-mentioned optical disc type discriminating device, and executes an operation according to the type of the optical disc held by the rotation operation mechanism.

That is, according to the present invention, an optical disc type discriminating apparatus capable of discriminating the type of an optical disc, such as a substrate having a different thickness, accurately and promptly, and an optical disc of plural types constituted by the optical disc type discriminating apparatus are provided. Therefore, it is possible to provide an optical disk player device which is capable of satisfactorily recording and reproducing information signals accurately and quickly.

[Brief description of drawings]

FIG. 1 is a block diagram of an optical disc type discriminating apparatus according to the present invention, in which, when an optical disc having a substrate thickness of 1.2 mm is mounted, a light beam focused and irradiated on a signal recording surface of the optical disc is on the signal recording surface. 6 is a graph showing the variation in the amount of reflected light of the light beam when the beam crosses the recording track, together with the positional relationship between the recording track on the signal recording surface and the beam spot formed by the light beam.

FIG. 2 is a diagram showing an optical disc type discriminating apparatus according to the present invention, in which, when an optical disc having a substrate thickness of 1.2 mm is mounted, a light flux which is condensed and irradiated on a signal recording surface of the optical disc is on the signal recording surface. 6 is a graph showing a bottom hold signal of a variation in the amount of reflected light of the light flux when the recording track of FIG.

FIG. 3 is a diagram showing an optical disc type discriminating apparatus according to the present invention, in which, when an optical disc having a substrate thickness of 0.6 mm is mounted, a light flux which is condensed and irradiated on a signal recording surface of the optical disc is on the signal recording surface. 6 is a graph showing the variation in the amount of reflected light of the light beam when the beam crosses the recording track, together with the positional relationship between the recording track on the signal recording surface and the beam spot formed by the light beam.

FIG. 4 is a diagram showing an optical disc type discriminating apparatus according to the present invention, in which, when an optical disc having a substrate thickness of 0.6 mm is mounted, a light flux focused and irradiated on a signal recording surface of the optical disc is on the signal recording surface. 6 is a graph showing a bottom hold signal of a variation in the amount of reflected light of the light flux when the recording track of FIG.

FIG. 5 is a block diagram showing a configuration of a discriminating circuit which constitutes the optical disc type discriminating apparatus.

FIG. 6 is a side view showing a configuration of a main part of an optical pickup device that constitutes the optical disc type determination device.

FIG. 7 is a front view showing a configuration of a light receiving unit of a photodetector of the optical pickup device.

FIG. 8 is a vertical sectional view showing a configuration of an objective lens of the optical pickup device.

[Explanation of symbols]

16 1st semiconductor laser, 17 2nd semiconductor laser, 22 objective lens, 23 photodetector, 10
1 1st type optical disk, 102 2nd type optical disk

Claims (2)

[Claims] 1. A rotating operation mechanism for holding and rotating an optical disk which is a recording medium for information signals, a light source, and a signal recording of an optical disk in which a light beam emitted from the light source is rotated by the rotating operation mechanism. An objective lens for focusing light on a surface, and a focus indicating the distance between the focal point of the light flux by the objective lens and the signal recording surface, based on the state of the light flux reflected from the signal recording surface. Focus error detection means for generating an error signal, and based on the focus error signal, the objective lens is operated to move in the direction of contact with and away from the optical disc so that the focal point of the light flux by the objective lens is on the signal recording surface. Focus servo means for positioning the light flux, reflected light quantity detection means for detecting the light quantity of the light flux of the light flux reflected from the signal recording surface, and the reflected light. A discriminating means for detecting a variation in the light quantity of the reflected light flux based on the detection result of the quantity detecting means, wherein the discriminating means is configured such that the rotation operating mechanism holds the optical disc and rotates it, and The disc type is discriminated on the basis of the variation amount of the light quantity of the reflected light flux when the light flux traverses the recording track on the signal recording surface of the optical disc while the focus servo means is operating. An optical disc type discriminating device. 2. A rotation operation mechanism for holding and rotating an optical disk which is a recording medium for information signals, a light source, and a signal recording of an optical disk in which a light beam emitted from the light source is rotated by the rotation operation mechanism. An optical pickup device having an objective lens for condensing light on a surface, an optical pickup device having a reflected light amount detecting means for detecting the amount of the reflected light beam of the light beam from the signal recording surface, and the signal recording surface of the light beam. Focus error detecting means for generating a focus error signal indicating the distance between the focal point of the light beam by the objective lens and the signal recording surface based on the state of the reflected light beam, and based on the focus error signal. The objective lens is moved toward and away from the optical disc, and the focal point of the light flux by the objective lens is set to the signal. Based on the detection result by the reflected light amount detection means in a state in which the focus servo means positioned on the recording surface and the rotation operation mechanism hold the optical disk for rotation operation and the focus servo means is operating. Then, the amount of variation in the amount of light of the reflected light flux is detected, and the type of disc is determined based on the amount of variation in the amount of light in the reflected light flux when the light flux traverses a recording track on the signal recording surface of the optical disc. An optical disc player device comprising: a discriminating unit that discriminates between the optical disc player and a control unit that executes an operation according to the type of the optical disc held by the rotation operation mechanism discriminated by the discriminating unit.