JP3480023B2 - Optical disk drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION The present invention relates to a recordable optical disc.
Irradiates the recording film of the laser with laser light to perform recording or reproduction
The present invention relates to an optical disk device such as a magneto-optical disk device. [0002] 2. Description of the Related Art For example, a magneto-optical disk drive is
For use as external storage for data
You. In this type of magneto-optical disk drive, recording / reproducing (writing
Focus / readout) is not performed.
Once the robot is turned off, it takes about 2-3 seconds to re-engage
Focus servo and track
To perform a still operation in which the servo is performed.
You. [0003] SUMMARY OF THE INVENTION In the above-described still operation,
Indicates that the laser light is continuously focused on the same track
The recording film of the magneto-optical disk
Ascend. If the temperature of the recording film rises repeatedly,
The recording characteristics deteriorate due to the deterioration of the recording film.
There is a problem that data is destroyed. Therefore, the present invention does not perform the recording / reproducing operation.
Laser beam is focused on the same track
Prevent deterioration of recording film by preventing continuous irradiation
To shorten the time required for recording and playback operations
It is intended to provide an optical disk device which can be used. [0005] [Means for Solving the Problems]ThisOptical disc according to the present invention
The laser device applies laser light to the recording film of a recordable optical disc.
In optical disc devices that perform recording or playback by irradiation
hand,A first method for detecting that laser light is focused on a recording film
The light detection unit and the first light detection unit are part of the configuration.
The laser light is applied to the recording film, which is larger in area than the first
A second light detection unit for detecting that the light is collected,
An offset obtained by adding an offset signal to the signal from the photodetector
Offset addition signal generating means for obtaining a summation signal, and recording
Focus actuator so that laser light is focused on the film
Focus actuator driving means for driving the
After the focus search is completed,
At the time of recording / reproducing operation for recording / reproducing from optical disk
Converts the signal from the first detector into a focus actuator
To the optical disk drive to record or
During pauses when neither playback nor playback is performed, the offset
Apply the addition signal to the focus actuator driving means.
Things. [0006] [0007] [0008] [0009] [0010] [0011] [0012] [Action]ThisIn the invention ofRecorded on an optical disc or
During pauses when neither playback from the optical disc is performed,
Second light detection for detecting that laser light is focused on the recording film
Offset addition signal obtained by adding an offset signal to the section signal
Is applied to the focus actuator driving means,
Move the scum actuator to the defocus state.
The laser beam is applied to the recording film in a defocused state.
Because the same track is continuously irradiated,
Even if the recording film temperature risesDeterioration can be prevented
It works. Also,Turn off the focus servo during this pause
Recording on an optical disk
When reproducing from, instead of the offset addition signal,
First optical detection for detecting that laser light is focused on the recording film
The output signal itself is the focus actuator driver
This is applied to the step, so that the focus
ComeShorten the time before recording or playback operation becomes possible
It is possible to reduce the size.Also, during recording and playback operation
Focuses the signal of the first photodetector with a small area.
This is applied to the actuator driving means.
The signal of the first photodetector is a highly accurate focus error signal.
To improve the accuracy of the focus servo.
It becomes possible. In addition, at the time of rest, the first light detection unit
Focus actuating the signal of the second photodetector with a large product
Data is applied to the data drive
Control range can be expanded, and defocus
The amount can be increased, and the deterioration of the recording film due to temperature rise is more complete.
It can be completely prevented. Also, a second light detection unit
Has a second photodetector as a part of its configuration.
The detector can be used efficiently and can be configured at low cost.
It becomes possible. [0013] [0014] [0015] [0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG.
An example will be described. This example is for a magneto-optical disk drive.
In this example, the servo method is the sample servo method.
This is an example. In FIG. 1, reference numeral 1 denotes a spindle motor.
The magneto-optical disk 2 is driven by the motor 1 at a constant angular velocity.
It is driven to rotate. Also, from a host computer (not shown)
The recording data of the controller 3 and the data buffer 4
Is supplied to the encoder / decoder 5 via the
The data processing (addition of error correction code, modulation, etc.) is performed.
The operation of the encoder / decoder 5 is transmitted to the controller 3.
Therefore, it is controlled. Description output from encoder / decoder 5
Recording data (modulation data) is a magnetic head for generating an external magnetic field
6 is supplied to the drive circuit 7. As a result, the magnetic
The head 6 generates a magnetic field corresponding to the recording data, and
Magneto-optical disk in cooperation with the laser beam from the head 8
Recording data is magneto-optically recorded in the data area of the disk 2. FIG. 2 shows an example of the configuration of the optical head 8.
You. Reference numeral 101 denotes a semiconductor laser.
The laser light from 01 is a collimator lens 102, a beam
Sectional shaping lens 103, polarizing beam splitter 104,
Magneto-optical data via mirror 105 and objective lens 106
The recording film of the disk 2 is irradiated. This magneto-optical disk 2
The reflected light from the
And the polarization beam splitter through the polarization beam splitter 104.
The light is incident on the litter 107. And polarization beam split
The light transmitted through the condensing lens 107 is
Incident on the photodetector 110 via the optical lens 109
Is done. Further, the light is reflected by the polarization beam splitter 107.
The polarized light is turned by the half-wave plate 111 by 45 °.
After being turned, the polarized beam
The light enters the liter 113. This polarization beam splitter
Light (p-polarized light) transmitted through 113 enters photodetector 114
Is reflected by the polarization beam splitter 113 (s
(Polarized light) is incident on the photodetector 115. Returning to FIG. 1, the photodetector 1 of the optical head 8
The output signals of 14, 115 are adders10Supplied to
Is done. Adder10Signal (RF signal
Is reflected light from the pit portion of the magneto-optical disk 2.
In a certain period, the signal corresponds to the recording data. FIG. 3 shows a sector in the sample servo system.
-Format is shown, and the header part is arranged first.
Then, a plurality of data sections are arranged. H
A servo byte SB is provided at the beginning of the header section and each data section.
A clock pitch is provided at the servo byte SB.
And wobble pits are preformatted. Also,
The header has a sector mark, sector address,
Rack address signals are recorded, but these signals are also
Preformatted in pits. The output signal of the adder 10 is a clock recovery circuit.
11 and the clock pitch of the servo byte SB.
Clock C based on the playback signal of the
K is played. This clock CK is used for system clocks in various parts.
Used as a lock. Also, the output signal of the adder 10
Is supplied to the address decoder 12 to reproduce the header.
Address data AD is obtained from the signal. This address
The data AD is supplied to the controller 3 for recording or re-recording.
Used for access control during birth. The output signal of the adder 10 is a tracking signal.
Of the servo byte SB.
Tracking based on the wobble pit playback signal
The error signal Et is detected. This tracking error
-The signal Et is supplied to the fixed terminal on the a side of the changeover switch 14.
Is done. The fixed terminal on the b side of the changeover switch 14
Random signal Sra or sine generated by generation circuit 15
A periodic signal Scy such as a wave or a triangular wave is supplied. in this case,
The periodic signal Scy is asynchronous with the rotation cycle of the magneto-optical disk 2.
It is assumed that The switching of the changeover switch 14 is performed by the control
The control is performed by the controller 3. That is, records or
Is connected to the a side during playback, and recording is
If no production is performed, it is connected to the b side. Selector switch
The output signal of 14 is servo as tracking error signal
It is supplied to the circuit 16. Also, a photodetector of the optical head 8
Reference numeral 110 (see FIG. 2) is a quadrant photodetector even if not described above.
The output signal of each detection unit is
7 is supplied. In this focus error detection circuit 17,
Indicates that the focus error signal Ef is detected by the astigmatism method.
This focus error signal Ef is sent to the servo circuit 16.
Supplied. The operation of the servo circuit 16 is controlled by the controller 3.
Controlled. The optical head 8 is controlled by the servo circuit 16.
Tracking servo and focus servo
And the address output from the address decoder 12
Seek control (radial feed
Control) is also performed. The optical detectors 114, 1 of the optical head 8
The output signal 15 (see FIG. 6) is supplied to a subtractor 18.
Is subtracted. A subtraction signal output from the subtractor 18
(MO signal) from the magneto-optical recording unit of the magneto-optical disk 2
During the period when reflected light can be obtained, it corresponds to the recorded data
Signal. The output signal of the subtractor 18 is the data detection circuit 1
9. In the data detection circuit 19, the reproduction signal
And the like, and the data detection is performed.
The data detected by the data detection circuit 19 is an encoder /
The data is supplied to the decoder 5 and decoded (error correction and demodulation).
Etc.) are performed. And encoder / decoder 5
The reproduced data output from the controller 3 and the data
The data is supplied to the host computer via the buffer 4. This embodiment is configured as described above,
When performing playback (writing or reading), switch
Switch 14 is connected to a side to detect tracking error
The tracking error signal Et detected by the circuit 13 is turned off.
Supplied to the servo circuit 16 through the a side of the changeover switch 14.
Therefore, based on the tracking error signal Et,
Tracking servo is performed well. On the other hand, when neither recording nor reproduction is performed,
Switch 14 is connected to the b side, and the signal generation circuit 14
Output random signal Sra or periodic signal Scy
To the servo circuit 16 via the b side of the changeover switch 14.
Provided as King error signal. Therefore, Landa
Tracking based on the system signal Sra or the periodic signal Scy
Servo is performed and tracking actuating
The data is controlled to swing in the radial direction. Therefore, in this example, recording or re-recording
If the tracking actuator does not
Radial method based on dam signal Sra or periodic signal Scy
The laser beam is focused on
When the recording film of the magneto-optical disk 2 is irradiated in the
If the same track is continuously illuminated,
To prevent deterioration of the recording film due to temperature rise
Can be. As described above, the periodic signal Scy is applied to the magneto-optical disk.
The rotation cycle that is asynchronous with the rotation cycle of
Recording film of the magneto-optical disk 2 when synchronized with
May be continuously irradiated with laser light.
That's because. In this embodiment, neither recording nor reproduction is performed.
Do not turn off the focus servo if the
In order to perform recording or playback,
Time before recording or playback becomes possible
Can be shortened. Next, with reference to FIG.
Two embodiments will be described. In FIG. 4, FIG.
Corresponding parts have the same reference characters allotted, and detailed description thereof will not be repeated.
I do. In the figure, a focus error detection circuit 1
The focus error signal Ef detected by the adder 21 is
Supplied to The adder 21 has an offset signal.
Issue V _OFIs supplied via the connection switch 22. Connection
The on / off of the switch 22 is controlled by the controller 3.
It is. That is, it is turned off when recording or playing back.
Is turned on when neither recording nor playback is performed.
You. The output signal of the adder 21 is a focus error signal.
Is supplied to the servo circuit 16. In the tracking error detection circuit 13,
The detected tracking error signal Et is provided by a changeover switch.
23 is supplied to the fixed terminal on the a side. This changeover switch
The fixed terminal on the b side of 23 is grounded. Changeover switch 23
Switching is performed under the control of the controller 3.
You. That is, when recording or reproducing, connect to the a side.
And when neither recording nor reproduction is performed,
Continued. The output signal of the changeover switch 23 is tracking
The error signal is supplied to the servo circuit 16. This example
The configuration is as described above, and the other configuration is the same as the example of FIG.
Is done. In this embodiment, recording or reproduction (writing)
Or read), the connection switch 22 is turned off.
Detected by the focus error detection circuit 17
The focus error signal Ef is used as it is in the servo circuit.
16, the focus error signal Ef
, The focus servo is performed satisfactorily. On the other hand, if neither recording nor reproduction is performed,
Since the connection switch 22 is turned on, a focus error
Offset signal V is applied to signal Ef_OFThe servo is the sum of
It is supplied to the circuit 16 as a focus error signal. So
Therefore, the optical head 8 is in a defocused state. The solid line in FIG. 5 shows the focus error signal Ef
An example of the relationship with the defocus amount is shown. Objective lens
Aperture ratio NA = 0.5, laser beam wavelength λ = 78
At 0 nm, record when the laser beam is most narrowed down
The spot diameter on the film is around 1 μm (see point A). Up
As described above, the connection switch 22 is turned on to focus.
The offset signal V is added to the error signal Ef._OFBy adding
It can be operated at point B and the defocus amount is 3-5
It is about μm. Therefore, in this embodiment, both recording and reproduction are performed.
Otherwise, the laser light will be
Is irradiated on the recording film of the recording disk 2,
Since the rise is almost inversely proportional to the defocus amount,
Even if the rack is continuously irradiated, the temperature rise of the recording film is small.
To prevent deterioration of the recording film due to temperature rise.
Can be stopped. When neither recording nor playback is performed
Do not turn off the focus servo.
Switch 22 is turned off and added to the focus error signal Ef
Offset signal V_OFInstantly focus by removing
Recording or playback operation.
It is possible to shorten the time until the operation becomes possible. When neither recording nor reproduction is performed,
Switch 23 is connected to the b side,
A ground signal is provided as a tracking error signal.
This is because in the defocus state as described above,
The tracking error detected by the king error detection circuit 13
The error signal Et has an extremely low level and is almost unreliable.
Because it is almost gone. Next, with reference to FIG.
Three embodiments will be described. In FIG. 6, FIG.
Corresponding parts have the same reference characters allotted, and detailed description thereof will not be repeated.
I do. In the figure, a focus error detection circuit 1
7, the focus error signal Ef detected by the switch
It is supplied to the fixed terminal on the side a of the switch 24. FIG. 7 illustrates this example.
Of the optical detector 110 of the optical head 8 (see FIG. 2)
And the output signals S of the photodetectors A to D._A~ S_DBut
Supplied to the focus error detection circuit 17,
As the focus error signal Ef (S_A+ S_C)-
(S_B+ S_D) Is obtained. This focus error signal E
f has high accuracy because the area of the photodetectors A to D is small.
It becomes Also, 25 is a focus error detection circuit.
is there. The focus error detection circuit 25 has an optical head.
Of the photodetectors A to H constituting the photodetector 110 of FIG.
Signal S_A~ S_HIs supplied and focus by astigmatism method
Error signal Ef_TwoAs (S_A+ S_C+ S_E+ S_G)-(S_B
+ S_D+ S_F+ S_H) Is obtained. This focus error
Signal Ef_TwoIs rough due to the large area of the photodetectors A to H.
It will be of precision. The focus error detection circuit 25 detects
Focus error signal Ef_TwoIs supplied to the adder 26
You. The adder 26 has an offset signal V_OF2But
It is supplied via the connection switch 27. Connection switch 2
7 is controlled by the controller 3. You
That is, when recording or playback is performed,
On the other hand, when neither recording nor reproduction is performed, it is turned on. The output signal of the adder 26 is supplied to the changeover switch 24.
Is supplied to the fixed terminal on the b side. This changeover switch 24
Switching is performed under the control of the controller 3.
You. That is, when recording or reproducing, connect to the a side.
And when neither recording nor reproduction is performed,
Continued. The output signal of the changeover switch 24 is
The error signal is supplied to the servo circuit 16. This example is
The other components are the same as those in the example of FIG.
It is. In this example, recording or reproduction (writing)
Or read), the changeover switch 24 is set to a
Side, the focus error detection circuit 17
The detected focus error signal Ef is set to the changeover switch 2
4 is supplied to the servo circuit 16 through the side a.
Of the focus sensor based on the focus error signal Ef of
The boring can be performed accurately. On the other hand, when neither recording nor reproduction is performed,
Switch 24 is connected to the b side and the connection switch
27 is turned on, the focus error signal Ef_Two
Offset signal V_OF2Is the changeover switch
Focus error in servo circuit 16 via b side of 24
Supplied as a signal. Therefore, the optical head 8 is
It is in the focus state. The broken line in FIG. 5 indicates the focus error signal Ef._Two
And the relationship between the distance and the defocus amount. With the solid line in the figure
Between the focus error signal Ef and the defocus amount.
The S-shaped area is wider than the
It can be seen that the control range of the ball is expanded. Therefore, this example
, The offset signal V_OF2To
The amount of defocus can be increased by laser light irradiation.
More completely prevent deterioration of the recording film due to temperature rise.
Can be. When neither recording nor reproduction is performed,
It does not turn off the cas servo, just like the example in FIG.
It can immediately return to the focus state,
Or to shorten the time until playback operation becomes possible.
Can be. In this case, the connection switch 27 is turned off.
Offset signal added to focus error signal Ef
V_OF2Except for the focus error signal Ef_TwoBy Four
After returning to almost the focus state with the cas servo,
Switch 24 to the a side to change the focus error signal.
High-precision focus servo with signal Ef
To In this embodiment, the focus error signal
No. Ef, Ef_TwoIs a part or all of the light of the photodetector 110
It is obtained using the output signal of the detection unit,
Can be used efficiently and can be configured at low cost.
You. Note that the focus error signals Ef, Ef_TwoGot
Separate light detectors with different areas to
You may. Next, with reference to FIG.
Fourth embodiments will be described. In FIG. 8, FIG.
Corresponding parts have the same reference characters allotted, and detailed description thereof will not be repeated.
I do. In the figure, a focus error detection circuit 1
7, the focus error signal Ef detected by the switch
It is supplied to the fixed terminal on the a side of the cable 28. Reference numeral 29 is attached to the optical head 8.
Position for detecting the position of the focus actuator
Position sensor. FIG. 9 shows the focus of the optical head 8.
3 illustrates the principle of a cue actuator. 41 is an objective lens,
43 is wound around a coil frame (also used as a lens holder) 42
Focus coil 44 is a yaw composed of an iron plate or the like.
And 45, a magnet. Focus coil 43
By supplying a drive current, the coil frame 42, and thus the objective lens,
Drive 41 in the direction perpendicular to the magneto-optical disk 2.
Then, focus adjustment is performed. From position sensor 29
Is the position of the focus actuator, that is, the objective lens
A signal Sp indicating the position of 41 is obtained. Returning to FIG. 8, the output signal of the position sensor 29
Sp is supplied to the subtractor 30 and is applied to the reference signal Sr.
The difference signal Ss is calculated. The reference signal Sr is
The output signal Sp of the position sensor 29 in the state
Set equal. Therefore, it is obtained by the subtractor 30
The difference signal Ss is determined by the focus of the focus actuator.
This indicates the displacement from the state position. Obtained by the subtractor 30
The difference signal Ss is a fixed terminal on the b side of the changeover switch 28.
Supplied to The changeover of the changeover switch 28 is performed by the control
The control is performed by the controller 3. That is, records or
Is connected to the a side during playback, and recording is
If no production is performed, it is connected to the b side. Selector switch
The output signal of 28 is a servo error signal as a focus error signal.
It is supplied to the road 16. In this example, the control lines are shown in FIG.
If neither recording nor reproduction is performed,
Semiconductor laser 10 constituting optical head 8 under control
1 (see FIG. 2) is stopped. Book
The example is configured as described above, and the others are the same as in the example of FIG.
Be composed. In this example, recording or reproducing (writing)
Or readout), the changeover switch 28 is set to a
Side, the focus error detection circuit 17
The detected focus error signal Ef is set to the changeover switch 2
8 is supplied to the servo circuit 16 through the side a.
Of the focus sensor based on the focus error signal Ef of
Baking can be performed well. On the other hand, when neither recording nor reproduction is performed,
Since the changeover switch 28 is connected to the side b, the subtractor 30
Output difference signal Ss focuses on the servo circuit 16
Since it is supplied as an error signal, the focus actuator
The eta is held substantially at the focus position. Only
However, if neither recording nor reproduction is performed as described above,
Since the emission of the light has been stopped,
It is possible to prevent deterioration of the recording film due to temperature rise. The focus actuator is almost completely
Because it can be held in the focus position
Immediately focus on recording or playback
When it is ready for recording or playback.
Time can be shortened. When performing recording or playback operations
Is to switch the changeover switch 28 from the b side to the a side.
However, unless the switching time is strict,
Large defocus due to warpage on disc surface
The switch 28 is switched by the amount of
Focus servo by error signal Ef becomes difficult
And so on. To avoid such inconvenience, FIG.
0 from the switching signal generator 40 as shown in FIG.
No. SW may be used. In the figure, the focus error
The focus energy detected by the detection circuit 17 (see FIG. 8)
The error signal Ef is supplied to the positive terminal of the comparator 41.
The negative terminal of the comparator 41 is grounded. From comparator 41
Becomes high level “H” when the signal Ef is positive.
When the signal Ef is negative, the signal becomes low level “L”.
A signal is obtained. That is, the output signal of the comparator 41 is
It falls at the zero-cross point of the focus error signal Ef.
Or a rising signal. The output signal of the comparator 41 is
The signal is supplied to the clock terminal of the D flip-flop 42,
The flip-flop 42 outputs the output signal of the comparator 41, for example.
It operates at the rising timing. The output from the adder 10 (see FIG. 8)
The supplied RF signal is supplied to an envelope detection circuit 44.
You. The envelope signal output from the detection circuit 44
S_RFIs supplied to the positive terminal of the comparator 43. Comparator 43
Is supplied with a reference signal Vref. Comparator 4
3, the envelope signal S_RFIs higher than the reference signal Vref
Is high level "H" and the envelope signal S
_RFIs low level “L” when is smaller than the reference signal Vref.
Becomes The output signal of the comparator 43 is a D flip-flop 4
2 clear terminal CLR. D flip-flop
When the output signal of the comparator 43 is at the low level “L”,
Is cleared. In the above configuration, as shown in FIG.
Focus error signal EfWhen B is obtained,
As shown, the envelope signal S_RFIs obtained, so that
From the lip flop 42, as shown in FIG.
, A switching signal SW that rises is obtained. That is,
The changeover switch 28 shown in FIG.
At time t1, switching from the b side to the a side immediately
Focus state, enabling recording or playback operation.
The time required to complete the process can be shortened. For example, magneto-optical
When the rotation speed of the air disk 2 is 3600 rpm
Is 60 msec / 1 rotation, so at least 60
The focus state can be set within msec. In the above embodiment, the magneto-optical
An example in which the present invention is applied to a disk device has been described.
Irradiating the recording film of a simple optical disc with laser light for recording or
It is similarly applicable to other optical disc devices that perform playback.
It will be suitable. [0064] 【The invention's effect】ThisAccording to the invention ofRecord on an optical disc
Or during pauses when neither playback from the optical disc is performed
Is a second method for detecting that laser light is focused on the recording film.
Offset signal obtained by adding an offset signal to the signal of the photodetector
Calculation signal is applied to the focus actuator driving means,
Defocus by moving the focus actuator
The laser beam is recorded in a defocused state.
Because the recording film is irradiated, even if the same track is continuously
Even if irradiatedTo prevent deterioration of the recording film due to temperature rise
Can be. Also,During this pause, the focus servo is turned off.
Recording or optical disc
When performing playback from the
And a first method for detecting that the laser light is focused on the recording film.
The signal itself of the light detector is used as the focus actuator drive.
Is applied to the moving means, and immediately
Can,Time until recording or playback operation becomes possible
Can be shortened.Also, at the time of recording / playback operation,
Focus actuation of the signal of the first photodetector with a small area
To the motor driver means, that is, this
The signal from the photodetector 1 is a high-precision focus error signal.
The accuracy of the focus servo can be improved.
You. Also, at the time of rest, the area is larger than that of the first light detection unit.
The signal of the second light detection unit is driven by the focus actuator.
Control means of the focus servo.
It is possible to enlarge the frame and increase the defocus amount
To completely prevent deterioration of the recording film due to temperature rise.
can do. Further, the second light detection unit is configured to output the second light
The detection unit is part of the configuration, and the light detection unit is efficient.
It can be used well and can be configured at low cost. [0065] [0066] [0067]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram showing a first embodiment of an optical disk device according to the present invention. FIG. 2 is a diagram illustrating a configuration example of an optical head. FIG. 3 Sector format (sample servo method)
FIG. FIG. 4 is a configuration diagram showing a second embodiment of the optical disk device according to the present invention. FIG. 5 is a diagram illustrating a relationship between an error voltage and a defocus amount. FIG. 6 is a configuration diagram showing a third embodiment of the optical disk device according to the present invention. FIG. 7 is a diagram illustrating a light detection unit of a photodetector for detecting a focus error. FIG. 8 is a configuration diagram showing a fourth embodiment of the optical disk device according to the present invention. FIG. 9 is a principle configuration diagram of a focus actuator. FIG. 10 is a configuration diagram showing a switching signal generator. FIG. 11 is a diagram showing operation waveforms of the switching signal generator. [Description of Signs] 1 spindle motor 2 magneto-optical disk 3 controller 5 encoder / decoder 6 magnetic head 8 optical head 10, 21, 26 adder 11 clock reproduction circuit 12 address decoder 13 tracking error detection circuit 14, 23, 24, 28 Changeover switch 15 Signal generation circuit 16 Servo circuit 17, 25 Focus error detection circuit 18, 30 Subtractor 19 Data detection circuit 22, 27 Connection switch 29 Position sensor 40 Switching signal generation device 41, 43 Comparator 42 D flip-flop 44 Envelope detection circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G11B ^7/ 09-7/ ¹⁰ G11B 11/10-11/105

Claims (1)

(57) [Claim 1] In an optical disk apparatus for performing recording or reproduction by irradiating a recording film of a recordable optical disk with a laser beam, it is preferable that the laser beam is focused on the recording film. No. to detect
A first light detection unit and the first light detection unit as a part of the configuration,
Laser light is focused on the recording film, which has a larger area than the projection
A second light detecting unit for detecting the fact that the offset signal is added to the signal from the second light detecting unit.
Offset addition signal generator to obtain the offset addition signal
Step and focus so that the laser light is focused on the recording film
Focus actuator drive actuator
Moving means, and after completion of the focus search, the
At the time of recording or reproducing operation for recording or reproducing from the above optical disk
The signal from the first detection unit to the focus
Apply to actuator driving means and record on optical disk
Or pause without performing any playback from the above optical disc
At times, the offset addition signal is transmitted to the focus
An optical disk device characterized in that the voltage is applied to a tutor driving means .