JP2927193B2 - Optical disk drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk apparatus for discriminating a pit area and a groove area on an optical disk for recording and reproducing.

[0002]

2. Description of the Related Art In recent years, in addition to CDs (compact disks) and LDs (laser disks), optical disks used as recording media are recordable and reproducible due to advances in light modulation technology and magnetic field modulation technology. Magneto-optical disk, MD
(Mini-disc) has appeared and is becoming popular.

For example, an MD has been commercialized as a rewritable music disk for consumer music, and a system for driving the MD is basically the same as an optical disk device (magneto-optical disk device). An audio compression process and a sound skipping gart memory for anti-vibration are newly added to perform recording for 74 minutes on an optical disk (MD) having a diameter of 64 mm.

FIG. 9 is an explanatory view of an optical disk. FIG. 9 shows an MD. FIG. 9A shows a reproduction-only MD, and FIG. 9B shows a rewritable MD. FIG. 10 is a partially enlarged explanatory view of FIG. A MD11 _A reproduction-only shown in FIG. 9 (A), the recording area (information area) 12 are all pit structure. The recording area 12 is composed of a lead-in area in which information on the contents of the disc is recorded, a program area in which the contents of the disc are recorded, and a lead-out area in which information indicating that the program area has ended is recorded. Be composed.

[0005] The pit structure is as shown in FIG.
A convex portion 12a having a predetermined size is formed as _a pit row in the track direction. The convex portion 12a is irradiated with _a laser beam, and the convex portion _12a is detected by reflected light. On the other hand, the MD 11 _B shown in FIG. 9B is rewritable, and the recording area 13 includes a pit area 13 _a having a pit structure and a groove area 13 _b having an MO (magneto-optical) structure. And has two tracking modes. The pit area _13a becomes the lead-in area,
The groove area 13 _b program area and the lead-out area is formed.

[0006] Further, the groove area _13b is formed as shown in FIG.
As shown in (B), a guide groove _13b1 is formed, the guide groove _13b1 is magnetized for recording, and the reproduction is performed by detecting the polarization state (car rotation) due to the magnetization. Although not shown, there is a so-called hybrid type MD in which a read-only area and a recordable / reproducible area are formed in a program area.

By the way, the rewritable MD11 _B has two tracking mode as described above, in a pit area 13 _a and the groove area 13 _b (described FIG. 12) the tracking servo polarity from the different Need to switch. Therefore, there is known a conventional optical disk device having a sample-and-hold circuit for determining which area it is.

FIG. 11 is a circuit diagram of a sample and hold circuit for area detection in a conventional optical disk device. In FIG. 11, reproduction signals RF ₁ and RF ₂ based on the reflected light of the laser beam applied to the MD 11 _B are input to the addition amplifier 21, and the output (sum signal) is output to the capacitor C.
The DC component is cut at 1 and input to the sample and hold circuit 22.

The sample-and-hold circuit 22 includes two diodes D1 and D2, a resistor R1, and a capacitor C2. The sum signal from the summing amplifier 21 is peak-held by the capacitor C2. Peel held sum signal is input to the comparator 23 is compared with a reference value, or pit area 13 _a or the groove area 13 _b is supplied to the determined by the microcomputer.

FIG. 12 is a diagram for explaining detection of a tracking error signal. FIG. 12A shows the pit area 1
3 shows the relationship between _a convex portion 12 _a and the laser beam to be irradiated (the main beam 24 _a and the side beams 24 _b on both sides thereof), two side beams 24 _b when moving across the tracks The tracking error signal TE1 is obtained from the difference in the amount of reflected light received at.

FIG. 12B shows a groove region _13b.
Guide grooves _13b1 and the irradiated laser beams _24a , 24a
shows the relationship is _b, the tracking error signal TE2 is obtained by the difference between the amount of received reflected light of the two side beams 24 _b as it moves across the track in the same manner as described above. The tracking error signal TE2 is the above tracking error signal TE1 guide groove 13 _b1 and the convex portion 12 _a
Becomes the reflection polarity due to the difference in the recording portion of.

The reproduced signal RF is transmitted from the main beam 24.
The reflected light of _a is received by the two light receiving elements,
_In the case of _a , it is obtained by a sum signal, and in the case of the groove area _13b , it is obtained by a difference signal. Therefore, FIG.
FIG. 3 is an explanatory diagram of an input waveform to a sample and hold circuit. In FIG. 13 (A), RF obtained in the pit area 13 _a
When 1 and RF2 are added by the addition amplifier 21 (FIG. 11), a normal RF signal is input to the sample hold circuit 22.

In FIG. _13B , RF1 and RF2 obtained in the groove area 13b are added to the summing amplifier 21.
, The output to the sample and hold circuit 22 becomes zero. That is, the difference between these pit area 13 _a and the groove area 13 _b of the RF waveform to the peak hold, a laser beam (optical head) is positioned in any region by comparing a predetermined reference value using a comparator 23 Can be determined.

Then, the pit area 13 _a
And performs a switching of the polarity of the tracking servo in the groove area 13 _b.

[0015]

However, switching of the polarity of the tracking servo has an important meaning when the tracking servo is started after the search.
For example, when the servo start is in the groove tracking mode despite a pit area 13 _a tracking servo is taken between pit rows, also servo start tracking mode pit row despite a groove area 13 _b If there is, the tracking servo is performed on the land surface between the guide grooves _13b1, so that the address information is not read out and a runaway state occurs.

In particular, the pit area _13a and the groove area 1
In the boundary portion between the 3 _b is missing takes time to response due to charging and discharging of the capacitor C2 of the sample-and-hold circuit 22 the accuracy of the search, and the servo area and tracking mode there is a problem that does not match. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an optical disk device capable of performing high-speed and accurate search.

[0017]

FIG. 1 is a block diagram showing the principle of the present invention. In FIG. 1, an optical disc having a pit area in which a pit row is formed as an information signal and a groove area in which a track guide groove is formed and information is recorded on a medium as described in claim 1 is described. In an optical disk apparatus for recording and reproducing the information on a predetermined track by moving an optical head in a radial direction of the optical disk, a holding unit 31 for holding a peak value of a reproduction signal by the optical head on the predetermined track; a setting means 32 for setting a tracking mode of the pit area or groove area according to an output from said <br/> hold means 31, the adjustment means 33 for adjusting the time constant of the hold means 31, the seek start the hole temporarily the time constant of the hold means 31 to the time of a small town, said end of seek
And control means 34 for controlling the adjusting means so as to restore the time constant of the adjusting means 31 to the original time constant .

According to a second aspect of the present invention, the control means according to the first aspect controls the pin of the hold means at the start of a seek operation.
The seek value holding operation is released, and when the seek operation ends, the peak
The control of the adjusting means 33 is performed so that the peak value holding operation is performed.

[0019]

[Action] In the present invention of claim 1 or 2 as described above, the adjusting means for adjusting the time constant of the hold means 31, the temporary control means 34 during the seek operation is started to the holding means 31
At the end of the seek operation.
Control is performed to control the adjusting means so that the time constant of 31 is returned to the original value, and the setting means 32 sets the tracking mode in accordance with the peak value obtained by holding the peak value of the holding means 31 after the cancellation. As a result, even when the optical head is located at the boundary between the pit area and the groove area, the peak value is held instantaneously, and the area can be searched quickly and accurately.

[0020]

FIG. 2 is a block diagram showing an embodiment of the present invention.
FIG. 3 shows a circuit diagram of the peak hold circuit of FIG. FIG. 2 shows a switching circuit 41 for switching a tracking servo between a pit area and a groove area of an optical disk (similar to FIGS. 9 and 10) in an optical disk apparatus. It is assumed that a main beam and two side beams (see FIG. 12) are irradiated.

The switching circuit 41 receives reflected light of the main beam from a predetermined track of the optical disk by the first and second light receiving elements 42 and 43, and outputs the respective outputs to a subtracter 44.
And supplied to the adder 45. The output of the subtractor 44 (groove reproduction output) and the output of the adder 45 (pit string reproduction output) are supplied to the switch circuit 46 and the adder 4
5 is supplied to the peak hold circuit 47. The switch circuit 46 outputs a reproduction signal RF.

The output from the peak hold circuit 47 is supplied to a comparator 48 as setting means, and is compared with a reference voltage V. The output of the comparator 48 is supplied to a microcomputer 49 as a control means. The microcomputer 49 supplies a control signal CTL for controlling the holding time of the peak value of the peak hold circuit 47 to the peak hold circuit 47 in accordance with a predetermined operation of the optical head.

On the other hand, 2
The reflected light of the two side beams is applied to the third and fourth light receiving elements 5
The light is received at 0,51, and the respective outputs are subtracted by subtracters 52,5.
3 and the outputs of the subtracters 52 and 53 are supplied to a switch circuit 54. In this case, the output of the subtractor 52 is the tracking error signal TE on the pit area, and the output of the subtractor 53 is the tracking error signal TE on the groove area. That is, the tracking error signal TE switched to each area by the switch circuit 54 is output.

The switch circuits 46 and 54 are controlled by a microcomputer 49 based on the output of a comparator 48 (a signal for determining whether the area is a pit area or a groove area). Further, as shown in FIG. 3, the peak hold circuit 47 includes a hold circuit 55 as a holding means and an adjusting circuit 56 as an adjusting means.

The hold circuit 55 includes two diodes D
3, D4, a resistor R2, and a capacitor C3. The diode D3 is connected to the signal line in the forward direction,
The other diode D4, resistor R2 and capacitor C3 are grounded from the signal line. The adjustment circuit 56 is connected from the signal line to the collector of the transistor Tr via the resistor R3, and the emitter of the transistor Tr is grounded. The base of the transistor Tr is connected to the microcomputer 49 via the resistor R4, and is biased by the control signal CTL. The transistor Tr
, An analog switch or the like may be used instead.

The operation of the peak hold circuit 47 will be described. The output signal from the adder 45 (FIG. 13A,
When the control signal CTL is at a low level and the transistor Tr of the adjusting circuit 56 is off, the peak value of the output signal is applied to the capacitor C3 when the sum signal of the addition result of (B) is input to the hold circuit 55. Charged (held), the comparator 48 compares the peak value with the reference voltage V, and supplies the microcomputer 48 with a determination signal as to whether the optical head is located in the pit area or the groove area of the optical disk. I do.

The comparator 48 is adapted to operate as shown in FIG.
As shown in FIG. 7, in the pit area, the held peak value is higher than the reference voltage, and a high-level discrimination signal is output. In addition, as shown in FIG. 13B, in the case of a groove area, the held peak value is zero, and a low-level discrimination signal is output. On the other hand, when the optical head performs a seek or a track jump, the control signal CTL from the microcomputer 48 becomes high level and the transistor Tr is turned on. Tr is discharged through the resistor R3, and the peak value holding operation is released. As a result, the capacitor C3 can be charged immediately after the control signal goes low.

That is, the peak hold operation is performed when the seek operation of the optical head is completed. Since the time constant is temporarily reduced until the tracking servo is started to improve the responsiveness, the optical head is improved. Moving the boundary between the pit area and the groove area is not affected,
An area search of the optical head can be performed quickly and accurately. This is effective not only for recording / reproducing MDs but also for hybrid MDs.

Here, FIG. 4 shows a configuration diagram of an optical disk apparatus to which the present invention is applied. In an optical disk device 61 shown in FIG. 4, an optical disk 63 (similar to FIGS. 9 and 10) controlled and rotated by a disk motor 62 is irradiated with a laser beam from an optical head 64, and a reproduced signal read by reflected light has an analog waveform. The signal is supplied to a synchronization detection circuit 66 and a PLL (Phase Locked Loop) circuit 67 via a shaping circuit 65.

The PLL circuit 67 compares the reproduced signal from the analog waveform shaping circuit 65 with a reference signal from the included oscillator, generates a reproduced clock for demodulation, and generates a synchronous detection circuit 66 and a signal processing circuit. 68 and a disk servo circuit 69. In the synchronization detection circuit 66, the PLL
The synchronization of the main signal is detected based on the reproduced clock from the circuit 67 and is supplied to the signal processing circuit 68 while maintaining the bit synchronization.

The signal processing circuit 68 has a function of performing processing such as error correction and D / A conversion on the supplied main signal, and the address information extracted in these processes is used as a track address detection circuit. The data is supplied to the microcomputer 49 via 70. The signal processing circuit 68 has a built-in sound skip guard memory, which performs a process of storing a sound for several seconds and reproducing the sound from the memory when the sound skips or cuts out due to disturbance such as vibration. is there.

The disk servo circuit 69 has a PLL
The optical disk 6 based on the reproduction clock from the circuit 67
3 is generated and supplied to the disk motor 62 for controlling the rotation of the motor 3 so that the linear velocity becomes constant (CLV). Therefore, in the disk servo circuit 69, servo by EFM (Eight to Fourteen Modulation) when scanning the pits and ADIP (Advertising) when scanning the grooves are performed.
Generates servo signals for control by switching between servos by dress in pregroove).

The microcomputer 49 controls the pickup servo circuit 71. The pickup servo circuit 71 performs focus control, tracking control, and feed control of the optical head 64 based on a reproduction signal from the optical head 64. The pickup servo circuit 71 performs control by switching the tracking polarity between pit scanning and groove scanning. That is, the switching circuit 41 (excluding the microcomputer 48) shown in FIG. 2 is provided.

On the other hand, at the time of recording, A /
The main signal is supplied to the head drive circuit 72 after performing D conversion, data (voice) compression, EFM modulation, and other adjustments. Since the MD employs a recording method based on magnetic field modulation, a recording-only head 73 provided on the upper surface side of the optical disc 63 is used.
Is recorded by the head driving circuit 72 and the head 7
3 is performed.

FIG. 5 shows a basic configuration diagram of the optical head of FIG. FIG optical head 64 shown in 5 is incident on the beam splitter 84 laser beam 82 _a emitted from the semiconductor laser 82 is a light source through a coupling lens 83, an additional 1/4 wavelength plate 85, objective lens 86 The optical disk 63 is irradiated with the light. On the other hand, the light reflected from the optical disk 63 is changed its optical path by a beam splitter 84 via an objective lens 86 and a 波長 wavelength plate 85, and is transmitted to a first light receiving element (photo diode) 42 via a condenser lens 87. While being received, a part of the reflected light is received by the second light receiving element 43 via the reflection mirror 88.

Further, the objective lens 86, the coil 89 _a for performing the tracking servo is provided, the coil 89 _b is provided to perform the focusing servo. The optical head 64 performs recording by irradiating the optical disk 63 with _a laser beam 82 _a having _a higher output than the semiconductor laser 82 at the time of recording, and magnetizing the optical disk 63 with the head 73.

Further, at the time of reproduction, by irradiating a laser beam 82 _a small output to the optical disk 63, performs reproduction by demodulating and receiving the reflected light by the first light receiving element 42. In this case, focusing servo is performed with the output signal of the first light receiving element 42, and a reproduction signal is obtained with the output of the second light receiving element 43. FIG. 5 shows the optical system of the main beam in the optical head 64.
Those comprising two side beams using a laser beam 82 _a of the optical system. A tracking error signal is generated by the side beam to perform tracking servo.

FIG. 6 is a circuit block diagram of the pickup servo circuit 71 shown in FIG. 6, a tracking error TE signal output from the switch circuit 54 of FIG. 2 is supplied to first and second phase compensation circuits 91 and 92, and a first speed detection circuit 93 and a first shaping circuit are provided. 94. The output of the first phase compensation circuit 91 is input to the driver 96 via the tracking servo switch S1 of the switch circuit 95,
At the output of 6 to drive the coil 89 _a for tracking servo. The output of the first speed detection circuit 93 is the first subtractor 9
7 is supplied. Further, the first shaping circuit 94 shapes the TE signal, and as the position information, the microcomputer 49
To supply. The output of the second phase compensation circuit 92 is input to the driver 98 via the reproduction switch S3 of the switch circuit 95, and the output of the driver 98
The motor 99 to be moved is driven.

On the other hand, an FG signal from a rotation detector provided near the motor 99 is supplied to the second speed detection circuit 100 and the second shaping circuit 101. The output of the second speed detection circuit 100 is supplied to a second subtractor 102. Further, the second shaping circuit 101 shapes the FG signal and supplies it to the microcomputer 49 as position information. Also,
The speed data output from the microcomputer 49 is converted into an analog signal by a D / A (digital / analog) conversion circuit 103, and the first and second subtracters 97, 1
02.

The output of the first subtractor 97 is the switch circuit 9
The output of the second subtracter 102 is input to the driver 98 via the seek switch S4 via the track jump switch S2 of FIG.
The switch circuit 95 is controlled by the microcomputer 49, and the switches S1 and S3 are simultaneously turned on.

FIG. 7 is a timing chart for explaining the operation of FIG. 2, and FIG. 8 is a flowchart for explaining the operation of the present invention during a seek operation. Now, assuming that the polarity of the tracking servo is for the pit area (FIG. 7C), when there is a seek command from the host device (step (ST1)), the tracking servo is turned off (FIG. 7D ), ST2), the switch S4 of the switch circuit 95 is turned on, and the motor 99 is driven along the speed profile to perform the coarse seek of the optical head 64 (ST3).

At this time, the control signal CTL from the microcomputer 49 becomes high level, the transistor Tr of the peak hold circuit 47 is turned on, and the peak value holding operation is released (FIG. 7A). When the coarse seek is completed, the control signal CTL becomes low level (FIG. 7A), the transistor Tr is turned off, the capacitor C3 performs the peak value holding operation, and the comparator 48 determines the area. (FIG. 7 (B), ST4). And the tracking servo Ts
The mode is switched (FIG. 7C).

When the Ts mode is switched, the tracking servo in the mode (for example, the groove area mode) is turned on (FIG. 7D, ST5), and the address is read (ST6). Then, a seek is performed by calculating the distance between the target value of the target track and the current position of the optical head 64 (ST7). It is determined whether the optical head 64 is at the target position. If not, the tracking servo is turned off (ST9), and the switch S2 of the switch circuit 95 is turned on to perform a track jump (S9).
T10), area determination is performed again (ST11), and ST5 is performed.
Return to Then, the seek ends when the optical head 64 is at the target position (ST12).

In the above embodiment, the case where the MD having the pit area and the groove area is used has been described. However, the present invention is not limited to the MD, and the optical disk having the pit area and the groove area may be used. It can be applied to an apparatus.

[0045]

According to the invention of claim 1 or 2 as described above, according to the present invention, the adjusting means for adjusting the time constant of the hold hand stage, when the control hand stage is temporarily-hold means during a seek operation is started
The time constant of the hold means a constant small city, at the time of the seek operation is completed
Performs control so as to perform control of the adjustment means back to the original number, setting hand stage tracking mode in response to rupees <br/> click value by the peak value holding hold hand stage after release Is set, the peak value is held instantaneously even when the optical head is at the boundary between the pit area and the groove area, and the area can be searched quickly and accurately.

[Brief description of the drawings]

FIG. 1 is a principle block diagram of the present invention.

FIG. 2 is a configuration diagram of one embodiment of the present invention.

FIG. 3 is a circuit diagram of the peak hold circuit of FIG. 2;

FIG. 4 is a block diagram of an optical disk device to which the present invention is applied.

FIG. 5 is a basic configuration diagram of the optical head of FIG. 4;

FIG. 6 is a circuit block diagram of the pickup servo circuit of FIG. 4;

FIG. 7 is a timing chart for explaining the operation of FIG. 2;

FIG. 8 is a flowchart for explaining an operation at the time of seek according to the present invention.

FIG. 9 is an explanatory diagram of an optical disk.

FIG. 10 is a partially enlarged explanatory view of FIG. 9;

FIG. 11 is a circuit diagram of a sample and hold circuit for area detection in a conventional optical disc device.

FIG. 12 is an explanatory diagram of detection of a tracking error signal.

FIG. 13 is an explanatory diagram of a waveform input to a sample and hold circuit.

[Explanation of symbols]

 41 switching circuit 42, 43, 50, 51 light receiving element 44, 52, 53 subtractor 45 adder 46, 54 switch circuit 47 peak hold circuit 48 comparator 49 microcomputer 55 hold circuit 56 adjustment circuit 61 optical disk device 63 optical disk 64 optical head 71 Pickup circuit

Claims (2)

(57) [Claims] An optical head is mounted on an optical disc having a pit area where a pit row is formed as an information signal and a groove area where a track guide groove is formed and information is recorded on the medium. is moved radially recording of the information on a given track, in an optical disk apparatus for reproducing, and a hold means for holding a peak value of the reproduced signal by the optical head on the predetermined track, the output from the hold means setting means for setting a tracking mode of the pit area or the groove area according an adjustment means for adjusting the time constant of the hold means, small city time constant temporarily the hold means during the seek start, the end of seek Control means for controlling the adjusting means so that the time constant of the holding means is returned to its original state. An optical disc device characterized by the following. 2. A seek operation according to claim 1, wherein
At the start, the peak value holding operation of the holding means is released.
At the end of the seek operation, the peak value holding operation is performed.
Optical disc apparatus and performs control of the adjusting means so that.