JP2000163753A - Optical disk player, optical pickup device and optical disk playing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct a reproducing signal waveform according to inclination by accurately detecting the inclination of an optical disk. SOLUTION: A photodiode provided in a hologram laser in an optical pickup unit 100 detects a sub-beam using a position having a fixed shift in a tangential direction holding the information track of an optical disk as a beam spot. An inclination error signal generation unit 110 detects the inclination of an optical disk OD by taking a difference between two signals generated by the photodiode of the hologram laser detecting a sub-beam. The optical pickup unit 100 reads the optical disk OD to reproduce an RF signal, and sends this to a waveform equalizing unit 120. The waveform equalizing unit 120 inputs the RF signal to a transversal filter capable of changing a correction characteristic according to the inclination of the optical disk OD detected by the inclination error signal generation unit 110, and corrects the waveform.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk reproducing apparatus for reproducing a signal recorded on an optical disk, and more particularly to an optical disk reproducing apparatus capable of correctly reproducing recorded information even when the optical disk is tilted.

[0002]

2. Description of the Related Art When a signal recorded on an optical disk is reproduced, an inclination occurs between the pickup and the optical disk due to warpage of the optical disk, eccentricity, vibration, rotation unevenness, etc. occurring during rotation. As a result, the optical axis of the objective lens on the pickup is displaced, and aberrations occur in the lens itself, and the signal cannot be reproduced correctly.
The dullness of the reproduced RF signal may increase to cause waveform interference. Conventionally, an RF signal reproduced in such a state has been corrected using a waveform equalizer having a fixed correction characteristic to reduce waveform interference of the reproduced signal. In this case, the correction characteristics of the waveform equalizer do not change,
Since a constant correction is performed irrespective of the lightness of the waveform interference, a sufficient correction effect could not be obtained. Also, Japanese Patent Application Laid-Open
Japanese Patent Laid-Open No. 0-143868 discloses an optical disk apparatus that detects the inclination of an optical disk by using a four-division photodiode and uses it for equalizing a reproduced signal.

[0003]

In the above prior art, the reproduction signal can be corrected in accordance with the tilt of the optical disk by the optical disk device disclosed in Japanese Patent Application Laid-Open No. H10-143868. The laser light reflected by the information track on which is written is used for detecting the inclination. For this reason, even if the optical disk is not tilted, the tilt may not be detected correctly due to a change in the reflected light intensity due to the pits.

[0004] The present invention has been made in view of the above situation, and is an optical disc reproducing apparatus capable of appropriately correcting an RF signal reproduced from an optical disc and finally correctly reproducing information recorded on the optical disc. The purpose is to provide. It is another object of the present invention to provide an optical disk device capable of correctly detecting the tilt of an optical disk.

[0005]

An optical disk reproducing apparatus according to a first aspect of the present invention includes an information track on which recording information is written and a separation area provided between the information tracks and separating the information tracks. An optical disc reproducing apparatus for reproducing recorded information by irradiating an optical disc with laser light, comprising: a laser diode for irradiating a main beam to the information track and irradiating a sub-beam to the separation area. A signal reproducing unit configured to detect a main beam reflected by the information track in the light irradiated by the light irradiating unit, and to reproduce a signal including information; Detecting the sub-beam reflected from the separation area in the light irradiated by the light irradiating means to determine the tilt amount of the optical disc. Tilt error signal generating means for generating a tilt error signal for determining the signal, and waveform equalizing means for correcting a signal reproduced by the signal reproducing means in accordance with the tilt error signal generated by the tilt error signal generating means. It is characterized by.

[0006] According to such a configuration, the sub-beam reflected in the separation region having a substantially constant reflectance is detected.
By generating a tilt error signal in accordance with the detected sub-beam, it is possible to correct the reproduced signal by manipulating the correction characteristics of the waveform equalizing means. Therefore, it is possible to accurately detect the tilt of the optical disk and correct the reproduced signal according to the degree of the waveform interference.

The waveform equalizing means includes a correction signal generating means for generating a correction signal for correcting the signal reproduced by the signal reproducing means in accordance with the inclination error signal generated by the inclination error signal generating means; It is preferable that the apparatus further includes a signal correction unit that adds the correction signal generated by the correction signal generation unit and the signal reproduced by the signal reproduction unit, and corrects the signal reproduced by the signal reproduction unit.

[0008] The waveform equalizing means may include a first delay circuit for delaying the signal reproduced by the signal reproducing means, and a first delay circuit for attenuating and inverting the signal reproduced by the signal reproducing means.
An attenuating circuit, a second delay circuit for delaying the output signal of the first delay circuit, a second attenuating circuit for attenuating and inverting the output signal of the second delay circuit, An output signal of the attenuation circuit, an output signal of the first delay circuit,
An adder for adding the output signal of the second attenuation circuit to the output signal of the second attenuation circuit, wherein the first and second attenuation circuits are configured to:
It is also possible to provide a means for increasing the gain as the tilt of the optical disc increases and decreasing the gain as the tilt of the optical disc decreases, so as to function as a transversal filter whose correction characteristic changes. This makes it possible to change the degree of signal correction according to the tilt of the optical disk, and perform appropriate correction according to the degree of waveform interference.

The light irradiating means includes means for irradiating the separation area with two sub-beams, and the tilt error signal generating means reflects the light irradiated by the light irradiating means on the separation area. Detect two sub-beams,
It is desirable to include means for generating two signals corresponding to the detected sub-beams and calculating a difference between the two signals to generate a tilt error signal. Thus, it is possible to generate a tilt error signal for correcting the signal.

[0010] The tilt error signal generating means may include means for detecting a sub-beam having a beam spot at two positions having a constant shift in the tangential direction with one of the information tracks of the optical disk interposed therebetween. .
Thus, regardless of whether the optical disk is tilted in the radial direction or the tangential direction,
The tilt of the optical disc can be detected as a single tilt amount.

Further, the tilt error signal generating means may include means for detecting a sub-beam having a beam spot at a position symmetrical with respect to a beam spot of a main beam irradiated by the light irradiating means. This makes it possible to more accurately detect the inclination of the signal reading section of the optical disc.

It is preferable that the information track of the optical disk is formed of, for example, a land, and the constant reflectivity area of the optical disk is formed of, for example, a groove.

An optical pickup device according to a second aspect of the present invention includes a means for irradiating a laser beam to a main beam and a sub beam onto an optical disc, and a detecting means for detecting a sub beam reflected by a separation area of the optical disc. Means for reproducing a signal recorded on an optical disc, comprising: means for outputting a tilt error signal corresponding to the tilt of the optical disc in accordance with the sub-beam detected by the detection means.

An optical disk reproducing method according to a third aspect of the present invention is a method for reading and reproducing recorded information by irradiating an optical disk with a laser beam. A sub-beam is radiated to a separation area provided between information tracks to separate the information tracks, and a sub-beam reflected from the separation area is detected to generate a tilt error signal corresponding to a tilt amount of the optical disk. Detecting a main beam reflected by the information track to generate a reproduction signal, and correcting the reproduction signal in accordance with the tilt error signal, whereby the reproduction signal can be corrected according to the tilt of the optical disc. I do. Further, it is preferable that the tilt error signal is specified by calculating a difference between two signals generated according to two sub beams.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical disc reproducing apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a configuration diagram showing a configuration of an optical disk reproducing apparatus according to an embodiment of the present invention. As shown, the optical disk reproducing device 150 includes an optical pickup unit 100, a tilt error signal generation unit 110, and a waveform equalization unit 120.

The optical pickup unit 100 includes an optical disk O
D is for reading and reproducing the signal recorded in D with a laser beam, and as shown in FIG. 2, includes a hologram laser 101 and a multi-beam detector 102. For example, a beam splitter 103, a concave lens 104
, The collimator lens 105 and the objective lens 106 constitute an optical system to reproduce signals recorded on the optical disk OD.

The hologram laser 101 includes a light emitting unit 101a composed of a laser diode and the like and a light receiving unit 101b composed of a photodiode and the like. The light emitting unit 101a irradiates the optical disk OD with one main beam, two sub beams, and two side beams. The light receiving unit 101b is for detecting a sub-beam used for tracking out of the reflected light from the optical disc OD and outputting a signal for specifying the amount of tilt of the optical disc OD.

FIG. 3 is a configuration diagram showing the configuration of the light receiving section 101b of the hologram laser 101. As shown
The light receiving portion 101b of the hologram laser 101 includes a four-division photodiode 101c and a photodiode 10c.
1d and 101e, the two photodiodes 101d and 101e detect a sub beam reflected by the optical disk OD to generate two light receiving signals, and send them to the tilt error signal generating unit 110.

The multi-beam detector 102 shown in FIG. 2 detects a main beam and a side beam reflected by the optical disk OD and reproduces an RF signal containing information. The photodiode 102 detects the side beam.
a and 102b, and a four-division photodiode 102c for detecting a main beam and for detecting a tracking error and a focus error. The multi-beam detector 102 receives the return light from the three information tracks on the optical disc OD by using the photodiodes 102a and 102a.
The 2b and 4-division photodiodes 102c can simultaneously detect and reproduce three tracks simultaneously. The photodiodes 102a and 102b and the four-division photodiode 102c detect the return light, reproduce the RF signal, and appropriately amplify the signal with an RF amplifier.
The signal is sent to 20 waveform equalization circuits 120a to 120c.

The tilt error signal generator 110 shown in FIG. 1 is for generating a tilt error signal corresponding to the tilt amount of the optical disk OD. As shown in FIG. D (analog / digital) converter 11
And 2. The differential amplifier circuit 111 includes a photodiode 101d (FIG. 3) provided in the hologram laser 101 of the optical pickup unit 100 and the photodiode 10d.
1e (FIG. 3), the difference between the two light receiving signals is obtained, and the A / D converter 112 generates a digitized tilt error signal in accordance with the difference to generate a waveform error equalizing section 120.
Send to

The waveform equalizer 120 shown in FIG. 1 is an RF signal corrector for correcting the waveform of the RF signal reproduced by the optical pickup 100 in accordance with the tilt error signal generated by the tilt error signal generator 110. And, as shown in FIG. 5, is constituted by three waveform equalization circuits 120a to 120c.

The waveform equalization circuits 120a to 120c have the same configuration as each other, and FIG.
FIG. 3 is a configuration diagram illustrating a configuration of a waveform equalization circuit 120a. FIG.
As shown in the figure, the waveform equalizing circuit includes a first delay circuit 1
21, a second delay circuit 122, and a first attenuation circuit 12
3, a second attenuation circuit 124, and an adder 125.

The first delay circuit 121 and the second delay circuit 122 are circuits for delaying an input signal by a time τ and outputting the delayed signal. The first delay circuit 121 receives an RF signal from the optical pickup unit 100 and sends an output signal to the second delay circuit 122 and the adder 125. Also, the second delay circuit 1
22 receives an RF signal from the first delay circuit 121 and sends an output signal to the second attenuating circuit 124.

The first attenuating circuit 123 and the second attenuating circuit 124 are circuits for creating a signal for correcting the waveform of the RF signal. The first attenuation circuit 123 includes a control amplifier 126 and an inverter 128.
The second attenuation circuit 124 includes a control amplifier 127 and an inverter 129.

The first attenuator 123 attenuates the RF signal received from the optical pickup 100 in accordance with the tilt error signal received from the tilt error signal generator 110, inverts the signal with the inverter 128, and adds the signal to the adder 125. Send to

The second attenuating circuit 124 attenuates the RF signal received from the second delay circuit 122 in accordance with the tilt error signal received from the tilt error signal generator 110, inverts the signal with an inverter 129, and adds the inverted signal. To the container 125. Here, the first attenuation circuit 123 and the second attenuation circuit 124 have the same configuration. That is, the control amplifiers 126, 1
27 has the same configuration, and the inverters 128 and 129 have the same configuration.

As shown in the schematic diagram of FIG. 7, the control amplifiers 126 and 127
This is an amplifier circuit that adjusts the gain C by switching a switch in accordance with a digitized tilt error signal from the controller. The control amplifiers 126 and 127 have gain characteristics approximately as shown in FIG. 8 with respect to the tilt amount θ of the optical disk OD. Thereby, according to the tilt error signal received from the tilt error signal generation unit 110,
The gain C increases as the inclination of the optical disk OD increases, and decreases as the inclination of the optical disk OD decreases.

Next, the operation of the optical disk reproducing apparatus according to the embodiment of the present invention will be described. The optical disc reproducing apparatus detects a sub-beam used for tracking in the return light from the optical disc OD, specifies the tilt amount of the optical disc OD, and adjusts the correction characteristic of the waveform equalizer 120 according to the specified tilt amount of the optical disc OD. It is a device that can be adjusted.

Light emitting section 101a of hologram laser 101
Is emitted from the optical disk OD,
Return light is detected by the light receiving unit 101b of the hologram laser 101 and the multi-beam detector 102.

FIG. 9 is a diagram showing the arrangement of the beam spots of the laser light irradiated on the optical disk OD. Here, the optical disc OD includes, for example, information tracks T1 to T3 formed of lands on which pits are formed and information tracks T1 to T3 formed of grooves or the like on which pits are not cut.
Are provided with separation regions A1 and A2 for separating the two.

The beam spot S1 indicates a beam spot of a side beam detected by the photodiode 102a, and the beam spot S2 indicates a four-division photodiode 1
02c indicates the beam spot of the main beam detected, and the beam spot S3 is the photodiode 102b
Shows the beam spot of the side beam detected by the. The beam spots S4 and S5 indicate the beam spots of the sub beams detected by the photodiodes 101d and 101e, respectively.

In order to irradiate the laser beam having such a beam spot on the optical disk OD, the laser beam emitted from the light emitting portion 101a of the hologram laser 101 is
First, a hologram laser 101 is divided into a main beam, side beams, and sub beams by a diffraction grating (not shown). After that, each beam passes through the beam splitter 103, is converted into parallel light by the collimator lens 105, and is condensed and irradiated on the optical disk OD by the objective lens 106.

The return light from the optical disk OD sequentially passes through the objective lens 106 and the collimator lens 105, is separated by the beam splitter 103, and the sub beam is detected by the light receiving portion 101b in the hologram laser 101, and the main beam The focus of the side beam is adjusted by the concave lens 104 and detected by the multi-beam detector 102.

The photodiode 102 a of the multi-beam detector 102 reads a signal recorded on the information track T 1 on the optical disk OD, converts the signal into an RF signal, and sends the RF signal to the waveform equalizing circuit 120 a of the waveform equalizing section 120. The photodiode 102b of the multi-beam detector 102 reads the signal recorded on the information track T3, converts the signal into an RF signal, and sends the RF signal to the waveform equalizing circuit 120b of the waveform equalizing unit 120.
4-division photodiode 1 of multi-beam detector 102
02c reads the signal recorded on the information track T2, converts it into an RF signal, and sends it to the waveform equalization circuit 120c of the waveform equalization unit 120.

The photodiodes 101d and 101e in the hologram laser 101 detect the sub-beams of the beam spots S4 and S5 having a certain displacement in the tangential direction with the information track T2 of the optical disk OD interposed therebetween.
The beam spots S4 and S5 are point-symmetric with respect to the beam spot S2 of the main beam.

The photodiodes 101d and 101e are
The light receiving signals for detecting the sub-beams reflected by the separation areas A1 and A2 of the optical disk OD and specifying the amount of tilt of the optical disk, respectively, are sent to the tilt error signal generator 11 respectively.
Send to 0. Thus, regardless of whether the optical disk OD is tilted in either the radial direction or the tangential direction, the output signal of the photodiode 101d and the photodiode 10d
A difference occurs between the output signal and the output signal 1e, and almost all the inclinations of the optical disk OD can be detected. Further, since the photodiodes 101d and 101e detect the sub-beams reflected by the separation areas A1 and A2 having a constant reflectance, the tilt of the optical disk OD can be accurately detected.

The multi-beam detector 102 detects the return light, outputs an RF signal X (t), and sends it to the waveform equalizer 120.

The tilt error signal generator 110 receives signals from the photodiodes 101d and 101e, the differential amplifier circuit 111 calculates the difference between the two signals, and converts the difference error signal according to the difference into an A / D signal. Converter 11
The signal is digitized by 2 and sent to the first attenuator 123 and the second attenuator 124 in the waveform equalizer 120.

The waveform equalizer 120 is a multi-beam detector 1
02 from the RF signal X (t) received from the first delay circuit 12
1 and input to the first attenuation circuit 123.

The first delay circuit 121 outputs the RF signal X
(T) is delayed by a time τ and sent to the second delay circuit 122 and the adder 125 as X (t−τ). On the other hand, the first attenuating circuit 123 receives the RF signal from the multi-beam detector 102.
Receiving the signal X (t), receiving the tilt error signal from the tilt error signal generation unit 110, adjusting the gain C of the control amplifier 126 according to the tilt error signal,
Signal CX for attenuating (t) and correcting the waveform
Create (t). The first attenuating circuit 123 inverts the signal CX (t) by the inverter 128 to obtain -CX (t).
Is sent to the adder 125.

The second delay circuit 122 delays the RF signal X (t−τ) received from the first delay circuit 121 by a time τ and sends it to the second attenuation circuit 124 as X (t−2τ). . The second attenuator 124 operates in the same manner as the first attenuator 123 and receives the signal X received from the second delay 122.
A signal −CX (t−2τ) is generated from (t−2τ) and sent to the adder 125.

The adder 125 receives the signal X (t−τ) received from the first delay circuit 121, the signal −CX (t) received from the first attenuation circuit 123, and the signal X (t−τ) received from the second attenuation circuit 124. The received signal −CX (t−2τ) is added, and an RF signal G (t) having an equalized waveform is output. Thereby, the input RF signal X (t) and the output R of the waveform
The F signal G (t) has a relationship represented by Expression 1.

G (t) = X (t−τ) −C ｛X (t) + X
(T−2τ)｝ Therefore, the waveform equalizing unit 120
Can correct the waveform of the reproduced RF signal according to the inclination of the optical disk OD.

For example, if the optical disk OD is not tilted,
It is assumed that the multi-beam detector 102 outputs an RF signal X (t) having no waveform interference as shown in FIG. At this time, the control amplifier 126 of the first attenuator 123 and the control amplifier 127 of the second attenuator 124 receive the slope error signal corresponding to the slope amount being zero from the slope error signal generator 110, and Is set to zero.

Accordingly, the waveform equalizer 120 does not correct the waveform of the RF signal X (t) supplied from the multi-beam detector 102, and outputs the output signal X (t−t) of the first delay circuit 121.
τ) is used as it is as the output signal of the waveform equalizer 120, and FIG.
An RF signal G (t) as shown in FIG.

On the other hand, when the tilt amount of the optical disc OD is θ1,
It is assumed that the multi-beam detector 102 outputs an RF signal X (t) as shown in FIG. At this time,
The control amplifier 126 of the first attenuating circuit 123 and the control amplifier 127 of the second attenuating circuit 124 receive the tilt error signal corresponding to the tilt amount θ1 from the tilt error signal generation unit 110, and receive the tilt amount shown in FIG. The gain is set to a gain C1 corresponding to θ1.

The waveform equalizer 120 receives the RF signal X (t) from the multi-beam detector 102 and inputs the same to the first delay circuit 121 and the first attenuation circuit 123. The first delay circuit 121 outputs a signal X as shown in FIG.
(T−τ) to output the second delay circuit 122 and the adder 1
25, and the second delay circuit 122 outputs the signal X (t−2)
τ) is output and sent to the second attenuation circuit 124.

The control amplifier 126 of the first attenuator 123 attenuates the RF signal X (t) by the gain C1 and outputs a signal C1 * X (t) as shown in FIG. Control amplifier 127 of second attenuation circuit 124
FIG. 11 shows that the signal X (t−2τ) is attenuated by the gain C1,
A signal C1 * X (t−2τ) as shown in (D) is output. The inverter 128 of the first attenuation circuit 123 and the second
The inverter 129 of the attenuating circuit 124 inverts the signals C1 * X (t) and C1 * X (t−2τ) and sends them to the adder 125.

The adder 125 adds the signal X (t−τ) received from the first delay circuit 121 to the signal −C1 * X (t) received from the first attenuation circuit 123 and the second attenuation circuit 124.
, And add the signal −C1 * X (t−τ) received from
An RF signal G (t) as shown in FIG. That is, G (t) shown in FIG.
From X (t−τ) shown in (B), C (t) shown in FIG.
1 * X (t) and C1 * X (t−2) shown in FIG.
τ) is removed. Thereby, the RF signal G (t) whose waveform has been corrected can be obtained.

Further, thereafter, the tilt amount of the optical disk OD becomes large, the tilt amount is θ2 (> θ1), and the multi-beam detector 102 outputs the RF signal X (t) as shown in FIG. It shall be output. At this time, the control amplifier 126 of the first attenuation circuit 123 and the control amplifier 127 of the second attenuation circuit 124 receive the tilt error signal corresponding to the tilt amount θ2 from the tilt error signal generating unit 110, and Gain C2 (> C1) corresponding to the amount of inclination θ2.

The first delay circuit 121 outputs a signal X (t−τ) as shown in FIG. 12 (B), and the second delay circuit 122 outputs a signal X (t−2τ). The control amplifier 126 of the first attenuation circuit 123
A signal C2 * X (t) as shown in FIG.
The control amplifier 127 of the attenuation circuit 124 of FIG.
2D, a signal C2 * X (t−2τ) is output, and inverters 128 and 129 output C2 * X (t−2τ), respectively.
(T), C2 * X (t−2τ) is inverted.

The adder 125 adds a first attenuation circuit 123 and a second attenuation circuit 124 to the output of the first delay circuit 121.
Of the RF signal G as shown in FIG.
(T) is output.

As described above, according to the optical disk reproducing apparatus 150, the correction characteristic of the waveform equalizer 120 is changed in accordance with the magnitude of the inclination θ of the optical disk OD, and the degree of the waveform interference is adjusted. Waveform equalization can be performed. Further, according to the optical disk reproducing device 150, the photodiode 101d provided in the hologram laser,
101e specifies the tilt amount of the optical disc OD by detecting the sub-beam used for tracking.
No new equipment is added to the optical system. Further, the sub-beams detected by the photodiodes 101d and 101e irradiate the separation area where the pits are not formed and the reflectance is substantially constant, so that the optical disk OD can be accurately detected.
Can be detected.

The present invention is not limited to the above embodiment, and various modifications and applications are possible. For example, the first attenuation circuit 123 and the second attenuation circuit 1 of the waveform equalizer 120
The configuration of 24 is not limited to those shown in FIGS. 6 and 7, and any circuit that can attenuate the RF signal by adjusting the gain according to the tilt amount of the optical disk OD can be used. For example, it is possible to use a circuit that performs gain adjustment and inverts a signal at the same time by using an inverting amplifier circuit as shown in FIG. Further, the gain characteristics of the control amplifiers 126 and 127 are not limited to those shown in FIG. 8 and can be arbitrarily changed. For example, the gain characteristics of the control amplifiers 126 and 127 may be curves as shown in FIG. Further, the multi-beam detector 1
02 can be arbitrarily changed in accordance with the number of tracks to be read in parallel. In this case, the waveform equalizing circuit of the waveform equalizing unit 120 is replaced with the photodiode of the multi-beam detector 102. A plurality of RF signals output from the multi-beam detector 102 may be prepared in parallel and the waveforms may be corrected in parallel. Of course, the multi-beam detector 102 may be a single-beam detector having only one photodiode.

In the above embodiment, the four-division photodiode 101c included in the light receiving portion 101b of the hologram laser 101 is described as not being used.
The four-divided photodiode 101c can be used for detecting a tracking error and a focus error.
In this case, the four-division photodiode 102c of the multi-beam detector 102 may be used as a normal non-division photodiode to reproduce the RF signal.

[0056]

As described above, according to the present invention, by changing the correction characteristics of the waveform equalizer according to the tilt of the optical disk, an appropriate waveform equalization according to the degree of waveform interference is achieved. It can be performed. In addition, the present invention
Since the sub-beam reflected by the track having a constant reflected light characteristic is used to detect the tilt of the optical disc,
The inclination of the optical disk can be accurately detected.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration of an optical disk reproducing device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a configuration of an optical pickup unit of the optical disc reproducing device according to the embodiment of the present invention.

FIG. 3 is a configuration diagram showing a configuration of a light receiving unit of a hologram laser provided in the optical disc reproducing apparatus according to the embodiment of the present invention.

FIG. 4 is a configuration diagram showing a configuration of a tilt error signal generation unit of the optical disc reproducing device according to the embodiment of the present invention.

FIG. 5 is a configuration diagram showing a configuration of a waveform equalization unit of the optical disc reproducing device according to the embodiment of the present invention.

FIG. 6 is a configuration diagram showing a configuration of a waveform equalization circuit included in the optical disc reproducing device according to the embodiment of the present invention.

FIG. 7 is a diagram illustrating a control amplifier included in the optical disc reproducing device according to the embodiment of the present invention;

FIG. 8 is a diagram for explaining gain characteristics of a control amplifier included in the optical disc reproducing device according to the embodiment of the present invention.

FIG. 9 is a diagram showing a beam spot of a laser beam irradiated on the optical disk by the optical disk reproducing device according to the embodiment of the present invention.

FIG. 10 is a diagram showing a specific example for explaining the operation of the optical disc reproducing device according to the embodiment of the present invention.

FIG. 11 is a diagram showing a specific example for explaining the operation of the optical disc reproducing device according to the embodiment of the present invention.

FIG. 12 is a diagram showing a specific example for explaining the operation of the optical disc reproducing device according to the embodiment of the present invention.

FIG. 13 is a diagram showing a modification of the attenuation circuit provided in the optical disc reproducing device according to the embodiment of the present invention.

FIG. 14 is a diagram showing a modified example of the gain characteristic of the control amplifier included in the optical disc reproducing device according to the embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 100 optical pickup unit 101 hologram laser 101a light emitting unit 101b light receiving unit 101c four-segment photodiode 101d, 101e, 102a to 102c photodiode 102 multi-beam detector 103 beam splitter 104 concave lens 105 collimator lens 106 objective lens 110 tilt error signal generator 111 Differential amplifier circuit 112 A / D converter 120 Waveform equalizer 120a to 120c Waveform equalizer 121, 122 Delay circuit 123, 124 Attenuator 125 Adder 126, 127 Control amplifier 128, 129 Inverter 150 Optical disk reproducing device OD Optical disk T1 to T3 Information track A1, A2 Separation area θ, θ1, θ2 Optical disk tilt amount C, C1, C2 Gain

Claims (10)

[Claims] 1. An information track on which recording information is written,
An optical disc reproducing apparatus for reproducing recorded information by irradiating a laser beam to an optical disc provided between information tracks and having a separation area separating the information tracks, wherein the information track is irradiated with a main beam, and the separation is performed. Light irradiating means for irradiating a sub-beam to an area; signal reproducing means for detecting a main beam reflected by the information track among light radiated by the light irradiating means and reproducing a signal containing information; A tilt error signal generating means for detecting a sub-beam reflected from the separation area in the irradiated light and generating a tilt error signal for specifying a tilt amount of the optical disc; and a signal reproduced by the signal reproducing means. An optical disc reproducing device comprising: a waveform equalizing unit that corrects according to the tilt error signal generated by the tilt error signal generating unit. Raw equipment. 2. A correction signal generating means for generating a correction signal for correcting a signal reproduced by the signal reproducing means according to the inclination error signal generated by the inclination error signal generating means; 2. A signal correction means for adding a correction signal generated by the correction signal generation means and a signal reproduced by the signal reproduction means, and correcting the signal reproduced by the signal reproduction means. An optical disc playback device according to claim 1. A first delay circuit for delaying a signal reproduced by the signal reproducing means; a first attenuating circuit for attenuating and inverting the signal reproduced by the signal reproducing means. A second delay circuit for delaying an output signal of the first delay circuit; and a second delay circuit for attenuating and inverting the output signal of the second delay circuit.
And an adder for adding an output signal of the first attenuation circuit, an output signal of the first delay circuit, and an output signal of the second attenuation circuit. The second attenuating circuit includes means for increasing the gain as the tilt of the optical disc increases and decreasing the gain as the tilt of the optical disc decreases according to the tilt error signal received from the tilt error signal generating means. Functioning as a transversal type filter whose correction characteristics change,
2. The optical disk reproducing apparatus according to claim 1, wherein: 4. The light irradiating means includes means for irradiating the separation area with two sub-beams, and the tilt error signal generating means reflects the light irradiated by the light irradiating means on the separation area. 3. The apparatus according to claim 1, further comprising means for detecting two sub-beams, generating two signals corresponding to the detected sub-beams, and calculating a difference between the two signals to generate a tilt error signal. An optical disc playback device according to claim 1. 5. The tilt error signal generating means includes means for detecting a sub-beam having a beam spot at two positions having a certain displacement in a tangential direction with one of information tracks of the optical disc sandwiched therebetween. The optical disk reproducing apparatus according to claim 3, wherein: 6. The tilt error signal generating means includes a means for detecting a sub beam having a beam spot at a position symmetric with respect to a beam spot of a main beam irradiated by the light irradiating means. An optical disk reproducing apparatus according to claim 4. 7. The optical disk reproducing apparatus according to claim 1, wherein the information track of the optical disk is constituted by a land, and the separation area of the optical disk is constituted by a groove. 8. A means for irradiating an optical disc with a laser beam divided into a main beam and a sub-beam, a detecting means for detecting a sub-beam reflected on a separation area of the optical disc, and a means for irradiating the optical disc in accordance with the sub-beam detected by the detecting means. An optical pickup device for reproducing a signal recorded on an optical disc, comprising: a tilt error signal output unit that outputs a tilt error signal according to the tilt. 9. An optical disc reproducing method for reading and reproducing recorded information by irradiating an optical disk with a laser beam, the method comprising: irradiating a main beam to an information track on which the recorded information is written; A sub-beam is applied to a separation area separating the information tracks, a sub-beam reflected from the separation area is detected to generate a tilt error signal corresponding to the tilt amount of the optical disk, and a main beam reflected from the information track is generated. Detecting and generating a reproduction signal, and correcting the reproduction signal according to the tilt error signal;
An optical disk reproducing method characterized in that a reproduction signal can be corrected according to the tilt of the optical disk. 10. The optical disk reproducing method according to claim 9, wherein the tilt error signal is specified by obtaining a difference between two signals generated according to two sub-beams.