JPH08138255A - Optical disk device - Google Patents

Abstract

PURPOSE: To simply and accurately adjust servo gains by switching connection between the variable resistor and fixed resistor of a gain adjusting circuit according to a pit region and a groove region. CONSTITUTION: The drawing illustrates a pickup servo as a main part in an optical disk device, being constituted of a RF amplifier 21, a gain adjusting circuit 24 and a servo amplifier 25. Focus error signal and a tracking error with their gains somewhat adjusted are outputted from the RF amplifier 21 and supplied to the servo amplifier 25 via the resistor R13 of the gain adjusting circuit 24 and the variable terminal of a variable VR11. The servo amplifier 25 performs focusing or tracking by driving an actuator coil 26a or 26b so as to slightly move the objective lens of the optical pickup. A connection point between the resistor R13 and the variable VR11 is grounded via a resistor R14 and a switch circuit 27 and the variable VR11 is grounded via a resistor R15. The switch circuit 27 is switched by a a CPU which is not illustrated corresponding to a pit region and a groove region on the optical disk of the optical pickup.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device for recording and reproducing information on an optical disk having a pit area and a groove area as an information recording medium.

[0002]

2. Description of the Related Art In recent years, optical discs used as recording media can be recorded and reproduced by progress of optical modulation technology and magnetic field modulation technology in addition to CD (compact disk) and LD (laser disk). Magneto-optical disk, MD
(Mini disk) has appeared and is becoming popular.

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

In the MD, information is recorded between a reproduction-only one in which pits are previously formed as an information signal and a guide groove (groove) of a track formed on the pit area and the MO (magneto-optical) film. There is a recording / reproducing device having a groove area. Playback-only M in recording / playback MD
Similar to D, the lead-in area and the lead-out area in which the disc information is recorded are prepit areas.

When irradiating the recording / reproducing MD with laser light, the pit area and the groove area have different reflectances, and the amount of reflected light varies from area to area. Therefore, the gains of the focus error signal and the tracking error signal generated by the reproduction light are different for each area.
Therefore, gain adjustment is performed in order to eliminate the gain difference for each region in the RF amplifier to which the focus error signal or the tracking error signal is input.

However, most of the RF amplifiers are integrated circuits, and the gains of the focus error signal and tracking error signal output from the RF amplifiers cannot be completely corrected in many cases. Therefore, an external gain adjustment circuit is added to the RF amplifier. Therefore, FIG. 4 shows a circuit diagram of a conventional gain adjusting circuit. The reproduction signal detected by the optical pickup in FIG. 4A is input to the RF amplifier 11. The reproduction signal is input to the focus error amplifier and the tracking error amplifier in the RF amplifier 11 to generate the focus error signal and the tracking error signal, respectively. R
The control signals RFSW0 and RFSW1 output from the CPU are input to the F amplifier 11. RF here
S0 is a signal indicating whether the disc is a high reflection film (reproduction-only disc) or a low reflection film disc (MO film disc), and RFSW1 is a signal indicating whether it is a pit area or a groove area. Is. The gain of the focus error signal and the tracking error signal is adjusted by the AGC circuit.

The output of the RF amplifier 11 is supplied to a series circuit of a variable resistor VR1 and a resistor R4 between grounds via a resistor R3 of a gain adjusting circuit 14, and a series of a variable resistor VR2 and a resistor R5 between grounds. Supplied to the circuit. The variable terminals of the variable resistors VR1 and VR2 are connected to the switch circuit 15, and the servo signal gain-adjusted by the variable resistors VR1 and VR2 is supplied to the servo amplifier 16 via the switch circuit 15. Servo amplifier 1
Reference numeral 6 drives a focus actuator coil (and tracking actuator coil) 17 that moves the objective lens of the optical pickup.

The switch circuit 15 is switched for each pit area and groove area by a control signal RFSW1 from the CPU. That is, the pit mode / groove mode switching signal RFSW1 is output from the CPU according to the size of the reproduction RF signal detected by the optical pickup (large is the pit region, small is the groove region), the switch circuits 13 and 15 are switched, and the resistance is switched. The voltage input to the servo amplifier 16 is changed by changing the value.

At this time, the voltage adjustment when the optical pickup is in the pit area and the voltage adjustment when the optical pickup is in the groove area are performed by individually adjusting the variable resistors VR1 and VR2. In addition, the gain adjustment circuit shown in FIG. 4B has one variable resistor, the changeover switch circuit is eliminated, and voltage adjustment is performed in either one of the areas, and the servo gain is shared between the pit area and the groove area. Is intended.

[0010]

However, in the gain adjustment of the circuit shown in FIG. 4A, the variable resistors VR1 and VR2 have to be adjusted respectively, which causes a problem that the number of adjustment steps increases. Further, in the case of the gain adjustment of the circuit shown in FIG. 4B, the adjustment process is reduced by adjusting only the variable resistor VR1, but the servo gain difference due to each area is ignored, and either There is a problem in that it is not possible to obtain an appropriate servo gain in each area in the mode.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide an optical disk device for easily and accurately adjusting a servo gain.

[0012]

In order to solve the above-mentioned problems, according to a first aspect of the present invention, an optical disc having a plurality of recording areas of different recording forms is subjected to focusing and tracking on a predetermined track of the optical disc to perform optical recording. In an optical disc device for recording and reproducing information by a pickup, a variable adjustment element for adjusting a gain of a focus error signal or a tracking error signal detected by the optical pickup from the optical disc and a variable adjustment element according to the area Switching means for switching the connection of the fixed adjustment element to the variable adjustment element, and control means for switching the switching means according to the area of the optical pickup on the optical disk. And the gain-adjusted focus error signal or tracking error signal Comprises a servo drive means for causing the focusing or tracking on the optical pickup optical disc, the constituting an optical disk apparatus by.

[0013]

As described above, in the invention of claim 1, the control means adjusts the gains of the focus error signal and the tracking error signal by switching the connection of the variable adjustment element and the fixed adjustment element of the switching means according to each area. Perform focus servo or tracking servo. As a result, the adjustment process is performed only with the variable adjustment element, and the fixed adjustment element is set with the gain difference according to the region, so that the servo gain can be adjusted easily and accurately.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a circuit diagram of a main part of an embodiment of the present invention. The circuit diagram of FIG. 1 shows a gain adjusting portion of a pickup servo circuit included in an optical disc device described later. In FIG. 1, the pickup servo circuit includes an RF amplifier 21, and the RF amplifier 21 has a focus error signal FE and a tracking error signal TE.
Generation, compensation correction circuit (binarized EFM
Signal output), laser light APC (Automatic Power Co
(ntrol) circuit, AGC circuit, etc.

The gain of the tracking error signal obtained from the side spot is switched according to RFSW0 described above, and the polarity of the tracking error signal is switched according to RFSW1. The tracking error signal switched to the proper polarity and the focus error signal formed by the main spot are input to the AGC circuit.
The gain of the AGC circuit is adjusted according to the change of the light amount signal obtained from the main spot. The light amount signal from the main spot is input to the AGC circuit through the SW operational amplifier. RFSW1 is input to the SW operational amplifier, and R
When FSW1 shows a groove area, it works as a voltage follower, and when it shows a pit area, LP
F is included so that the reproduction component due to the pit can be removed.

The FE or TE whose gain has been adjusted to some extent is output from the AGC circuit, and the resistor R of the gain adjusting circuit 24 is output.
It is supplied to the servo amplifier 25 through the variable terminal of the variable resistor VR11 which is a variable adjusting element. The servo amplifier 25 has a focusing actuator coil 26 _a.
Alternatively, the tracking actuator coil _26b is driven to finely move the objective lens of the optical pickup described later to perform focusing or tracking.

The connection point between the resistor R13 and the variable resistor VR11 is grounded via the resistor R14 which is a fixed adjusting element and the switch circuit 27 which is a switching means. The variable resistor VR11 is grounded via the resistor R15. In addition,
The switch circuits 23 and 27 are control means (CP
U) allows switching according to the area of the optical pickup on the optical disk.

Here, FIG. 2 shows an overall block diagram of an optical disk device in which the gain adjusting circuit of FIG. 1 is mounted. 2A is an overall block diagram, and FIG. 2B is a main configuration block diagram of the pickup servo circuit. In the optical disc device 31 shown in FIG. 2A, an optical disc 34 controlled and rotated by a disc motor 32 is irradiated with a laser beam from an optical pickup 34, and a reproduction signal (RF) read by reflected light is converted into an analog waveform shaping circuit. Synchronization detection circuit, PLL (Phase Locked Loop) circuit, signal processing circuit,
The signal is supplied to the signal processing unit 35 including a track address detection circuit, a head drive circuit, and the like.

The PLL circuit compares the reproduction signal from the analog waveform shaping circuit with the reference signal from the included oscillator to generate a reproduction clock for demodulation, and the synchronization detecting circuit outputs from the PLL circuit. The synchronization of the main signal is detected by the reproduction clock and supplied to the signal processing circuit while maintaining the pit synchronization. The signal processing circuit has a function of performing error correction, D / A conversion, and the like on the supplied main signal, and the address information extracted in these processes is transferred from the track address detection circuit to the bus 36. It is supplied to a CPU (Central Processing Unit) 37 which is a control means via the. This signal processing circuit has a built-in sound skip guard memory, in which a sound for several seconds is stored in memory and is reproduced from the memory when a sound skip or sound break occurs due to disturbance of the vibrator. .

The reproduction signal (RF) from the optical pickup 34 is supplied to the pickup servo circuit 38, and the pickup servo circuit 38 is controlled by the CPU 37 via the bus 37. The reproduction signal (RF) from the pickup 34 is supplied. Based on the above), focus control, tracking control, and feed control of the pickup 34 are performed. Further, the pickup servo circuit 38 performs control by switching the tracking polarity between the pit scanning and the groove scanning.

The disk motor 32 is controlled by the disk servo circuit 39, and when performing CLV control on the optical disk 33, a signal processing unit (PLL) is used.
A servo signal for controlling the rotation of the optical disc 33 so that the linear velocity is constant (CLV) is generated based on the reproduction clock from the circuit 35 and is supplied to the disc motor 32.

On the other hand, at the time of recording, the signal processing unit 35 adjusts A / D conversion, data (sound) compression, EFM modulation, etc., and supplies the main signal to the head drive circuit. Since the MD adopts a recording method by magnetic field modulation, the head drive circuit controls the drive of the head 40 by the recording dedicated head 40 provided on the upper surface side of the disk 33.

Here, the optical disc 33 is a reproduction-only MD.
, The entire area has a pit structure like the CD, and the lead-in area of the optical disc 33 has a pit structure and the recording area and the lead-out area have a groove structure in the recording / reproducing MD. A rewritable MD for recording / reproduction has two tracking modes of a pit area and a groove area, and the tracking polarities are inverted between the pit area and the groove area.

Further, as shown in FIG. 2B, the pickup servo circuit 38 has the RF amplifier 21 as a main component,
An amplifier 22, a gain adjusting circuit 24, and a servo amplifier 25 are provided. The RF amplifier 21 uses a reproduction signal RF from the optical pickup 34 and an error detecting circuit 22 _a to amplify _a focus error signal FE and a tracking error signal TE.
Is to be supplied to

Next, FIG. 3 shows a block diagram of the optical pickup of FIG. The optical pickup 34 shown in FIG. 3 has a laser beam 41 _a emitted from a semiconductor laser 41 which is a light source.
Via the coupling lens 42 to the beam splitter 4
The light enters 3 and the quarter wave plate 44 and the objective lens 4
It is irradiated onto the optical disc 33 through the beam line 5. On the other hand, the light reflected by the optical disc 33 is the objective lens 45, 1/4
The optical path is changed by the beam splitter 43 through the wave plate 44, and is received by the first light receiving element (photodiode) 47 through the condensing lens 46, and part of the reflected light is passed through the reflection mirror 48 and The light is received by the second light receiving element 49.

The objective lens 45 has a tracking actuator coil 76 _b for tracking servo.
Together are provided, a focusing actuator coil 26 _a is provided to perform the focusing servo.
The optical pickup 34 as described above outputs the laser light 41 _a having _a higher output than the semiconductor laser 41 during recording to the optical disc 33.
The recording is performed by irradiating the magnetic recording medium and magnetizing it with the head 40.

Further, at the time of reproduction, reproduction is performed by irradiating the optical disc 33 with a laser beam 41 _a of _a small output and receiving the reflected light by the first light receiving element 47 for demodulation. In this case, focusing servo is performed by the output signal of the first light receiving element 47, and a reproduced data signal is obtained by the output of the second light receiving element 49. Although FIG. 3 shows the optical system of the main beam in the optical pickup 34, it is provided with an optical system of two side beams using the laser light 41 _a of the semiconductor laser 41. It is generated and tracking servo is performed.

Then, returning to FIG. 1, the gain adjustment will be described. Here, the focus error signal and the tracking error signal output from the amplifier 22 of the RF amplifier 21 make use of the fact that the gain difference between the pit area and the groove area of the optical disc 33 is constant. The resistance value of the corresponding resistor 14 is set. In this case, the variable resistor VR11 is for fine adjustment to maintain a constant gain difference.

Now, the CPU 37 uses the optical pickup 3
It is determined from the reproduction signal RF whether the signal No. 4 is located in the pit area or the groove area of the optical disc 33, and the switch circuit 27 is switched by the recognition signal RFSW1. That is, the pit area having a high reflectance is turned on, and the groove area having a small gain is turned off.

Next, a specific example will be described. For example, assuming that the gain of the pit area is 3 dB higher than the gain of the groove area, R13 = 2.2 KΩ,
R14 = 5.1KΩ, R15 = 22KΩ, VR11 = 2
Set to 0KΩ. Therefore, the gain variable range by the variable resistor VR11 is the maximum gain G _gmax in the groove mode (the switch circuit is in the off state): G _gmax = 20log {(VR11 + R15) / (R13 + VR11 + R15)} = 20log {(20 + 22) / (2.2 + 20 + 22)} = 20log (42 / 42.2) ≈−0.44 [dB].

The minimum gain G _gmin is: G _gmin = 20log {(R15 / (R13 + VR11 + R15)} = 20log {22 / (2.2 + 20 + 22)} = 20log (22 / 44.2) ≈-6. It becomes 06 [dB].

On the other hand, in the pit mode (switch circuit 27
Is on), the maximum gain G _pmax is G _pmax = 20log [{R14 // (VR11 + R15)} / {R13 + R14) // (VR11 + R15)}] = 20log [{5.1 // (20 + 22)} / {(2.2 + 5.1) // (20 + 22)}] = 20log [{4.55 / (2.2 + 4.55)} = 20log (4.55 / 6.75) ≈ -3.43 [dB] Become.

The minimum gain G _pmin is: G _pmin = G _pmax + 20log {R15 / (VR11 + R15)} = G _pmax + 20log {22 / (20 + 22)} ≈ -3.43 + (-5.62 ) = − 9.05 [dB].

As described above, the gain difference of 3 dB can be maintained. In this way, one is fixed resistor R
Only one variable resistor VR11 needs to be adjusted as 13, and the gain difference can be made substantially constant, so that the servo gain can be adjusted easily and accurately. In addition,
In the above embodiment, the adjustment of the gains of the tracking servo and the focus servo is represented by one system, but since the input / output lines and the gains of the servos are different from each other, the adjustment circuits are provided separately for the tracking servo and the focus servo. And are adjusted individually. In the above embodiment, the gain is switched by the control signal RFSW1 from the CPU.
Not limited to this, the gain may be switched by RFSW0. That is, since this is a circuit that adjusts the gain that cannot be completely corrected for a large change in the light amount signal, the gain may be switched by a signal indicating that this change occurs.

In the above embodiment, the case where the optical disc is an MD is shown, but the present invention is not limited to this, and the present invention can be applied to an apparatus used for an optical disc having a plurality of recording areas having different recording modes and having different reflected light amounts. is there.

[0036]

As described above, according to the invention of claim 1,
The control means switches the connection of the variable adjustment element and the fixed adjustment element of the switching means according to each area to adjust the gain of the focus error signal and the tracking error signal to perform focus servo or tracking servo,
By adjusting only the variable adjustment element in the adjustment process and setting the fixed adjustment element with the gain difference according to the region, the servo gain can be adjusted easily and accurately.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a main part of an embodiment of the present invention.

FIG. 2 is an overall block diagram of an optical disk device equipped with the gain adjustment circuit of FIG.

FIG. 3 is a configuration diagram of the optical pickup of FIG.

FIG. 4 is a circuit diagram of a conventional gain adjustment circuit.

[Explanation of symbols]

21 RF Amplifier 24 Gain Adjusting Circuit 25 Servo Amplifier 26 _a Focusing Actuator Coil 26 _b Tracking Actuator Coil 27 Switch Circuit 31 Optical Disc Device 32 Disc Motor 33 Optical Disc 34 Optical Pickup 35 Signal Processing Unit 37 CPU 38 Pickup Servo 39 Disc Servo Circuit

Claims (1)

[Claims] 1. An optical disc apparatus for performing recording and reproduction of information by an optical pickup by performing focusing and tracking on a predetermined track of the optical disc for an optical disc having a plurality of recording areas having different recording forms. A variable adjustment element that adjusts the gain of a focus error signal or a tracking error signal detected by an optical pickup and a fixed adjustment element that is set with a gain difference according to the region with respect to the variable adjustment element, and the variable adjustment Switching means for switching the connection of the fixed adjustment element to the element, control means for switching the switching means according to the area of the optical pickup on the optical disk, and the optical signal by the gain-adjusted focus error signal or tracking error signal. Focusing the pickup onto the optical disk An optical disc device comprising: a servo drive unit for performing tracking or tracking.