JP2003099963A - Method for driving optical pickup, optical pickup, and optical disk apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an optical pickup simplifiable and miniaturizable and to make preventable various kinds of deterioration in the characteristics by applying to the case in which an aberration correcting mechanism is constituted of a liquid crystal, for example, which relates to a method of driving optical pickup, an optical pickup, an optical disk apparatus. SOLUTION: Driving signals S0 and S3 for an actuator and driving signals S1 and S3 for the aberration correction mechanism 16 are multiplexed and transmitted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup driving method, an optical pickup and an optical disc device,
For example, it can be applied to a case where the aberration correction mechanism is composed of liquid crystal. INDUSTRIAL APPLICABILITY The present invention can simplify and downsize an optical pickup even when the aberration correction mechanism is composed of a liquid crystal or the like by multiplexing and transmitting the drive signal of the actuator and the drive signal of the aberration correction mechanism.
Furthermore, it is possible to prevent various characteristic deteriorations.

[0002]

2. Description of the Related Art Conventionally, in an optical pickup of an optical disc device, an actuator for moving an objective lens has been downsized in accordance with a higher transfer rate and a higher density of an optical disc.
It is required to reduce the weight.

Further, in an optical pickup, it is required to reproduce data more accurately than a pit row formed with high density, and therefore, an arrangement of an aberration correction mechanism for correcting the aberration of a laser beam has been proposed. There is.

That is, when the numerical aperture of the objective lens is increased as the density of the optical disc is increased, in the optical pickup, a beam spot having a predetermined shape is formed on the information recording surface of the optical disc due to the aberration due to the variation of the thickness of the optical disc. Becomes difficult. As a result, crosstalk increases in the reproduction signal that is the result of receiving the return light,
In addition, the C / N ratio deteriorates, which causes the error rate to deteriorate in the optical disk device.

Japanese Patent Laid-Open No. 2000-131603 discloses an aberration correction mechanism for correcting such an aberration.
A configuration has been proposed in which a lens is disposed between an objective lens and a laser light source, and the wavefront of a laser beam is corrected by this lens.

[0006]

By the way, in such an aberration correcting mechanism, it is considered that it is difficult to sufficiently correct the aberration due to a positional deviation between the objective lens and the objective lens. It is conceivable to integrally hold the lens and the aberration correction mechanism.

In this case, however, the objective lens and the aberration correction mechanism are integrally moved by the actuator, and the mass of the movable object in the actuator increases, which makes it difficult to reduce the size and weight of the optical pickup. Become. In particular, when accessing an optical disc having a multi-layer information recording surface, it becomes difficult to reduce the size because the movable range of the aberration correction mechanism becomes large.

Therefore, it is conceivable to configure the aberration correction mechanism by liquid crystal instead of the aberration correction mechanism by such a lens. That is, if the aberration correction mechanism is composed of liquid crystal, it is considered that the mass of the movable object can be reduced as compared with the case where the aberration correction mechanism is composed of the lens even if it is moved by the actuator together with the objective lens. Therefore, it is considered suitable for downsizing and weight reduction of optical pickups.

However, when the aberration correction mechanism is composed of the liquid crystal, it is necessary to supply a driving signal to the liquid crystal, and the supply line of this signal makes the structure of the optical pickup complicated. is there. That is, in the conventional actuator, a voice coil for tracking control (which is a tracking coil) and a voice coil for focus control (which is a focus coil) are arranged on the objective lens side, and these two types of voice coils are fixed. Placed in the magnetic circuit held on the side,
By driving these two types of voice coils in accordance with the tracking error signal and the focus error signal, tracking control and focus control are performed. Accordingly, if a signal supply line for driving the liquid crystal is further provided, it is inevitable that the structure of the optical pickup becomes complicated accordingly.

In the case where such a signal supply line for driving the liquid crystal is provided, it becomes difficult to move the actuator at a high speed, and when the signal supply line is simply composed of a cable. If so, the tension of the cable may change due to the movement, and the objective lens may not be able to move smoothly.

Incidentally, in the current optical pickup, a suspension which is an elongated rod-shaped spring is used to hold the movable side and to configure signal supply lines for two types of voice coils. Therefore, a method of increasing the number of suspensions for signal transmission for driving the liquid crystal can be considered, but this increases the weight of the movable portion and further increases the spring constant of the suspension.
These also make it difficult to drive the actuator at high speed. It is also difficult to downsize the optical pickup.
It also becomes difficult to maintain the balance of spring constants of the suspensions.

The present invention has been made in consideration of the above points. Even when the aberration correction mechanism is composed of a liquid crystal or the like, the structure can be simplified, the shape can be reduced, and various characteristic deteriorations can be prevented. The present invention proposes an optical pickup driving method, an optical pickup, and an optical disk device.

[0013]

In order to solve such a problem, the invention of claim 1 is applied to an optical pickup driving method to provide an aberration correction mechanism for correcting the wavefront of a laser beam incident on an objective lens, It is held together with the objective lens, and the transmitter drives the actuator drive signal,
The drive signal of the aberration correction mechanism is multiplexed to generate a transmission signal, and this transmission signal is transmitted to the movable target side of the actuator. In the demodulation circuit of this movable target side, the actuator drive signal, aberration The drive signal of the correction mechanism is separated.

According to a ninth aspect of the present invention, the aberration correction mechanism is applied to an optical pickup and is held integrally with an objective lens to correct the wavefront of a laser beam incident on the objective lens. A demodulation circuit that is movably held and that separates a drive signal of the actuator and a drive signal of the aberration correction mechanism from a transmission signal transmitted from the fixed side of the actuator is provided.

According to a fifteenth aspect of the present invention, the invention is applied to an optical disk device and is held integrally with an objective lens,
An aberration correction mechanism that corrects the wavefront of the laser beam that enters the objective lens, a drive signal generation circuit that generates a drive signal for the actuator and a drive signal for the aberration correction mechanism, a drive signal for the actuator, and a drive signal for the aberration correction mechanism are multiplexed. The transmission unit, which generates the transmission signal and transmits the transmission signal to the movable target side of the actuator, and the objective lens are movably held together, and the transmission signal is used to drive the actuator drive signal and the aberration correction mechanism. And a demodulation circuit for separating the drive signal of.

According to the structure of claim 1, an aberration correction mechanism, which is applied to the driving method of the optical pickup and corrects the wavefront of the laser beam incident on the objective lens, is integrally held together with the objective lens, and is transmitted by the transmitter. , The drive signal of the actuator and the drive signal of the aberration correction mechanism are multiplexed to generate a transmission signal, and the transmission signal is transmitted to the movable target side of the actuator. By separating the drive signal of the actuator and the drive signal of the aberration correction mechanism, even when the objective lens and the aberration correction mechanism are held together and movable, the drive signal of the actuator and the aberration correction mechanism The drive signal can be transmitted to a movable object for processing. As a result, it is possible to prevent an increase in the transmission path due to an increase in the number of signals used for transmission, simplify the configuration, and further reduce the size. In addition, it is possible to secure high-speed movement and smooth movement of the movable object, which is almost the same as in the case where the signal of the aberration correction mechanism is not transmitted, whereby various characteristic deteriorations can be prevented.

According to a ninth aspect of the invention, the aberration correction mechanism is applied to an optical pickup, is held integrally with an objective lens, and corrects a wavefront of a laser beam incident on the objective lens, and is integrated with the objective lens. The objective lens and the aberration correction mechanism are provided by including a demodulation circuit that is movably held by the actuator and separates the actuator drive signal and the aberration correction mechanism drive signal from the transmission signal transmitted from the fixed side of the actuator. Even when they are held and moved integrally, the actuator drive signal and the aberration correction mechanism drive signal can be transmitted to the movable object and processed by a small number of transmission paths. As a result, it is possible to prevent an increase in the transmission path due to an increase in the number of signals used for transmission, simplify the configuration, and further reduce the size. In addition, it is possible to secure high-speed movement and smooth movement of the movable object, which is almost the same as in the case where the signal of the aberration correction mechanism is not transmitted, whereby various characteristic deteriorations can be prevented.

According to a fifteenth aspect of the present invention, it is applied to an optical disk device and is held together with an objective lens to correct the wavefront of a laser beam incident on the objective lens, and an actuator drive signal. , A drive signal generation circuit that generates a drive signal for the aberration correction mechanism, a drive signal for the actuator, and a drive signal for the aberration correction mechanism are multiplexed to generate a transmission signal, and the transmission signal is transmitted to the movable side of the actuator. By including a transmitter and a demodulation circuit that is movably held integrally with the objective lens and separates the drive signal of the actuator and the drive signal of the aberration correction mechanism from the signal for transmission, the objective lens and the aberration correction mechanism are provided. Even when they are held and moved together, the optical pick-up for the drive signal of the actuator and the drive signal of the aberration correction mechanism is made possible by a small number of transmission lines. Tsu can be processed and transmitted to the movable object flop. As a result, it is possible to prevent an increase in the transmission path due to an increase in the number of signals used for transmission, simplify the configuration, and further reduce the size. In addition, it is possible to secure high-speed movement and smooth movement of the movable object, which is almost the same as in the case where the signal of the aberration correction mechanism is not transmitted, whereby various characteristic deteriorations can be prevented.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings as appropriate.

(1) First Embodiment (1-1) Configuration of the First Embodiment FIG. 2 is a block diagram showing an optical disk device according to an embodiment of the present invention. In this optical disc device 1,
The optical disc 2 is a phase change type optical disc capable of high density recording. The spindle motor 3 drives the optical disc 2 to rotate at a predetermined rotation speed under the control of the servo circuit 4.

The optical pickup 5 irradiates the optical disc 2 with the laser beam L1, receives the returned light, and outputs the light reception result. As a result, the optical disc apparatus 1 is configured to generate the tracking error signal TE and the like by processing the result of the received light and further reproduce the data recorded on the optical disc 2. Further, the optical pickup 5 intermittently raises the light amount of the laser beam L1 applied to the optical disc 2 by a drive circuit (not shown), thereby sequentially forming pit rows on the optical disc 2 and recording desired data.

The matrix circuit (MA) 6 performs current-voltage conversion processing on the light reception result output from the optical pickup 5, and then performs matrix calculation processing, whereby the tracking error signal TE whose signal level changes according to the tracking error amount. , A focus error signal FE whose signal level changes according to the focus error amount, the optical disc 2
A wobble signal whose signal level changes according to the meandering of the groove formed in the above, a reproduction signal RF whose signal level changes according to the pit row formed on the optical disc 2, and the like are generated. For this reason, the optical disc apparatus 1 is adapted to process the reproduction signal RF to reproduce the data recorded on the optical disc 2.

The jitter detection circuit 7 detects and outputs the jitter amount of the reproduction signal RF by binarizing and processing the reproduction signal RF obtained from the embossed pits or recording marks of the optical disc 2.

The controller 8 controls the operation of the entire optical disk device 1 by executing a predetermined processing procedure.
In this control, the controller 8 calculates the control value of the aberration correction mechanism arranged in the optical pickup 5 based on the jitter detection result obtained from the jitter detection circuit 7, and based on the calculation result, the drive signal S1 of the aberration correction mechanism. And S3
Is output.

The servo circuit 4 outputs drive signals S0 and S4 for tracking control and focus control used to drive an actuator arranged in the optical pickup 5 with reference to the tracking error signal TE and the focus error signal FE. . With these components, the servo circuit 4 and the controller 8 constitute a drive signal generation circuit that generates a drive signal for an actuator that moves the objective lens and a drive signal for the aberration correction mechanism.

The rectangular wave signal generation circuit 9 has a DC level of 0.
A rectangular wave signal S2 having a duty ratio of 50% which is a level and a sufficiently large amplitude value as compared with the drive voltage of the aberration correction mechanism arranged in the optical pickup 5 is generated and output. The transmitter 10 multiplexes the drive signals S0 and S4 for tracking control and focus control, and the drive signals S1 and S3 for the aberration correction mechanism to transmit the drive signal S1.
0 to S13 are generated and these drive signals S10 to S13 are output to the optical pickup 5.

In the optical disc device 1, the optical pickup 5 is subjected to tracking control, focus control, and the aberration correction mechanism is driven by these drive signals S10 to S13.

FIG. 3 is a side view showing the optical system of the optical pickup 5. The optical pickup 5 is a laser diode 1 which is integrated with a light quantity monitor mechanism into an integrated circuit.
1 emits a laser beam L1 and the grating 1
2 produces 0th order and ± 1st order diffracted light. The optical pickup 5 transmits the laser beam L1 by the 0th order light and the ± 1st order diffracted light through the subsequent polarization beam splitter 13 and guides it to the collimator lens 14, which converts the laser beam L1 into substantially parallel rays. After the light is polarized by the subsequent quarter-wave plate 15, it is condensed on the information recording surface of the optical disc 2 by the high numerical aperture objective lens 17 composed of two lenses 17A and 17B.

The optical pickup 5 comprises the quarter wave plate 1
5 and the objective lens 17 between the aberration correction mechanism 1 by the liquid crystal.
6 is arranged, and the aberration correction mechanism 16 corrects the aberration of the laser beam L1.

Thus, by irradiating the optical disc 2 with the laser beam L1 through such an optical path,
In the optical pickup 5, the return light of the laser beam L1 follows the optical path of the laser beam L1 in reverse, and in the optical pickup 5, the polarization beam splitter 13 separates this return light from the optical path of the laser beam L1. .

The optical pickup 5 processes this return light by the multi-lens 19 and then receives it by the light receiving element 20 having a plurality of light receiving surfaces of a predetermined shape. The optical pickup 5 outputs the light reception result of the light receiving element 20 to the matrix circuit 6 described above. In the optical disc device 1, the tracking error signal TE is generated by the differential push-pull method by the processing of the return light by the multi-lens 19 and the subsequent processing by the matrix circuit 6 of the light reception result by the light receiving element 20, and the astigmatism is obtained. The focus error signal FE is generated by the method.

In the optical pickup 5, the objective lens 17 and the aberration correction mechanism 16 of the optical system thus arranged are integrally held, and are integrally driven by the actuator 21. As a result, the optical pickup 5 can effectively avoid the positional deviation between the objective lens 17 and the aberration correction mechanism 16 and avoid the deterioration of the characteristics due to the positional deviation.

FIG. 4 is a perspective view showing the actuator 21 that integrally holds the objective lens 17 and the aberration correction mechanism 16 as described above, as seen from the laser diode side, and FIG.
FIG. 5A is a plan view showing the actuator 21 as seen from the optical disk 2 side, and FIG. 5B is a perspective view as seen from the side with a partial cross section taken.

The actuator 21 holds the optical system on the suspension base 26 by means of a suspension 25 which is an elongated bar-shaped spring. Here, the suspension base 26 is a holding member that is held by the base material of the optical pickup 5, and is made of a resin material or the like, and four terminals 27 for respectively inputting the drive signals S10 to S13 are arranged on the back surface. The actuator 21 is the suspension 2
One end of 5 is connected to each terminal 27, and the suspension 25
The other end of the terminal is configured to project to the side opposite to the side on which the terminal 27 is arranged.

The actuator 21 has a bobbin 28 made of a resin material at the other end of the suspension 25.
Is retained. Here, the bobbin 28 is the lens holder 2
The objective lens 17 is held via 9 and the aberration correction mechanism 16 is held. Further, the bobbin 28 has a tracking coil 30 and a focus coil 31 wound around it. The actuator 21 is configured such that the suspension 25 is bent by this, so that the objective lens 17 and the aberration correction mechanism 16 can be integrally moved in various directions.

The actuator 21 is provided with a pair of magnets 33 so as to sandwich the bobbin 28 with a predetermined gap therebetween, whereby the tracking coil 3 is formed.
0 to drive the objective lens 1 as indicated by arrow A.
7. The aberration correction mechanism 16 is integrally movable in the radial direction of the optical disc 2, and the objective coil 17 and the aberration correction mechanism 16 are moved integrally as shown by arrow B by driving the focus coil 31. The distance to the optical disc 2 can be changed.

FIG. 6 is an exploded perspective view showing the structure of the aberration correction mechanism 16 integrally held with the objective lens 17 in this way. The aberration correction mechanism 16 is configured by stacking glass substrates 16A, 16B and 16C with a liquid crystal sandwiched therebetween. Here, in the central glass substrate 16B, transparent electrodes 16BA and 16BB are formed on substantially the entire surfaces of both surfaces, and in the upper and lower glass substrates 16A and 16C, the transparent electrodes 16AB and 16BB are formed on the surfaces facing the transparent electrodes 16BA and 16BB, respectively. 16 CA is formed. The transparent electrodes 16AB and 16CA are formed on the glass substrate 16
It is designed to be connected at B.

Each of the transparent electrodes 16AB and 16CA has a circular inner peripheral side electrode formed at the center thereof, and a ring-shaped outer peripheral side electrode is formed so as to surround the inner peripheral side electrode. These inner and outer electrodes are voltage-divided by the resistance, and predetermined drive signals SS1 and SS2 are applied between the transparent electrodes 16BA and 16BB of the glass substrate 16B facing each other, whereby the aberration correction mechanism 16 is applied. The aberration is corrected by correcting the wavefront of the laser beam L1 that passes through.

The aberration correction mechanism 16 includes the upper and lower glass substrates 1
6A and 16C, the central glass substrate 16B is formed to have a large area so that the central glass substrate 16B partially protrudes, and the flexible wiring substrate has a large area as shown by an arrow C. 39 are arranged.

Here, the flexible wiring board 39 is
Voltage dividing resistor R for dividing the above-mentioned drive signals SS1 and SS2
D1 to RD4 are mounted, and further drive signals S10 to S13
Demodulation circuit 42 for generating drive signals SS1 and SS2 from
It is designed to implement. Thus, in the optical pickup 5, the drive signals S10 to S13 output from the transmission unit 10 via the suspension 25 are input to the flexible wiring board 39, and the flexible wiring board 39 also includes the tracking coil 30 and the focus coil 31. Are connected. As a result, in the optical pickup 5, the flexible wiring board 39 can be effectively used to simplify the work of connecting the tracking coil 30 and the focus coil 31. Further, by effectively utilizing the limited space of the optical pickup 5, the voltage dividing resistors RD1 to RD4 are mounted, and further, the demodulation circuits of the drive signals SS1 and SS2 are mounted.

In the following, the liquid crystal thus held by the glass substrates 16A and 16B, the transparent electrodes 16AB and 16BA corresponding to the liquid crystal, and the voltage dividing resistor RD.
The integrated structure of 1 and RD2 will be described by appropriately calling it the A liquid crystal 40. Similarly, a liquid crystal held by the glass substrates 16B and 16C and a transparent electrode 16B corresponding to the liquid crystal.
The integrated configuration of B, 16 CA, and the voltage dividing resistors RD3, RD4 will be described by appropriately calling it the B liquid crystal 41.

FIG. 1 shows these drive signals SS1 and SS2.
It is a block diagram which shows the demodulation circuit 42 which produces | generates with. In the transmission unit 10 of the optical disc device 1, the limiter 45, as shown in FIG.
2 (FIG. 7A), the positive amplitude value and the negative amplitude value are limited by the signal levels VUP and VLO of the drive signals S1 and S2 of the aberration correction mechanism 16 and output (FIG. 7).
(B) and (C)). In addition, in this FIG. 7, Vd is
It is an ON voltage of diodes D1 and D2 arranged in a demodulation circuit 42 described later.

The differential amplifier 46 is a differential amplifier circuit in which the negative side differential input terminal is held at a constant voltage, receives the output signal of the limiter 45 at the positive side differential input terminal, differentially amplifies, and inputs. An in-phase output S6 having the same phase with respect to the terminal and an opposite-phase output S7 having the opposite phase with respect to the input terminal are output.

The adder circuit 48 adds this in-phase output S6 to the drive signal S0 for tracking control, which is one of the drive signals for the actuator, and outputs it.
Reference numerals 9 and 50 amplify the output signal of the adder circuit 48 and the in-phase output S6 by a constant gain and output the amplified signal. In the optical disc device 1, the pair of output signals S10 and S11 thus obtained are guided to the optical pickup 5 through the pair of lines, and further, two pairs of terminals among the four pairs of terminals 27 and the suspension 25 described above. The signal is transmitted to the movable object of the actuator 21 by a pair of lines formed by 27 and the suspension 25. As a result, in the optical disc device 1, the pair of lines for transmitting the drive signal S0 for tracking control is connected to the drive signal S of the aberration correction mechanism 16.
By biasing in common according to 1, the tracking control drive signal S0 and the aberration correction mechanism 16 drive signal S2 are multiplexed and transmitted.

Similarly, the adder circuit 53 adds the negative phase output S7 output from the differential amplifier 46 to the focus control drive signal S4, which is the remaining one of the actuator drive signals, and outputs the result. Drive circuits 54 and 55
Outputs the output signal of the adder circuit 53 and the anti-phase output S7 after amplifying each with a constant gain. In the optical disc device 1, a pair of output signals S1 thus obtained
2 and S13 are also guided to the optical pickup 5 by a pair of lines, and further, an actuator is formed by a pair of lines formed by the remaining two sets of terminals 27 and suspension 25 among the above-mentioned four sets of terminals 27 and suspension 25. It is transmitted to 21 movable objects. As a result, in the optical disc device 1, the pair of lines for transmitting the drive signal S4 for focus control is connected to the drive signal S of the aberration correction mechanism 16.
By biasing in common in accordance with No. 3, the focus control drive signal S4 and the aberration correction mechanism 16 drive signal S3 are multiplexed and transmitted.

Further, after limiting the positive-side amplitude value and the negative-side amplitude value of the rectangular wave signal S2 with the duty ratio of 50 [%] by the signal levels of the drive signals S1 and S3, respectively, the polarities are inverted and biased in this way. By generating the signals to be supplied, when the two pairs of lines are biased in this way and the drive signals S1 and S3 are transmitted, even if the reference level of the bias is not reproduced on the transmission target side, these drive signals S1 And S3 can be demodulated.
Due to these, in the optical disk device 1, the aberration correction mechanism 16
Even if the lens is held together with the objective lens 17 and is movable,
The signal for driving the aberration correction mechanism 16 can be transmitted without increasing the transmission path, and the optical pickup 5 can be made smaller and lighter by that amount, and further, various characteristics deterioration due to the increase in the number of lines. Has been designed so that it can be effectively avoided.

Thus, in the optical pickup 5, the above-mentioned flexible wiring board 39 once receives the drive signals S10 to S14 thus obtained, and among these drive signals, the drive signals S10, S11, and S12.
By connecting the lines of S and S13 to the corresponding tracking coil 30 and focus coil 31, respectively,
These tracking coil 30 and focus coil 31
Are driven by the common mode of the drive signals S10 and S11, S12 and S13 to perform tracking control and focus control.

That is, assuming that the signal levels of the in-phase output S6 and the anti-phase output S7 are Lc and -Lc, respectively, and the signal levels of the drive signals S0 and S4 are Aa and Ab, the signal levels of the drive signals S10 and S11 are Aa respectively
In contrast to + Lc and Lc, the signal levels of the drive signals S12 and S13 are represented by Ab-Lc and -Lc, respectively. As a result, the potential difference Va at both ends of the tracking coil 30 is represented by S10-S11 = (Aa + Lc) -Lc, and eventually the tracking coil 30 can be driven by the signal level of the drive signal S0. Similarly, the potential difference Vb across the focus coil 31 is S12.
It is represented by -S13 = (Ab-Lc)-(-Lc), and after all, the focus coil 31 can be driven by the signal level of the drive signal S4.

The demodulation circuit 42 uses the biases of these lines to drive signals SS1 and SS of the A liquid crystal 40 and the B liquid crystal 41.
Generates 2. That is, as shown in FIG. 8, the demodulation circuit 42 simply includes the in-phase component S of the drive signals S11 to S13.
6 and the drive signals S11 and S12 on the side biased by the negative phase component S7 are input to the detection circuit 57. Here, the potential difference between the drive signals S11 and S12 corresponds to a signal level of which the amplitude value is limited by one drive signal S1 during the period in which the signal level of the rectangular wave signal S2 is rising, and During the period in which the signal level of the signal S2 is falling, by corresponding to the signal level whose amplitude value is limited by the other driving signal S2, the driving signals S11 and This indicates the signal level of S12.

According to this principle, the demodulation circuit 42 detects the drive signals S11 and S12 by the detection circuit 57, whereby the positive side having the peak values corresponding to the positive limit value and the negative limit value in the limiter 45. A detection signal and a negative detection signal are generated. High pass filter (HPF) 5 that continues
The direct current level is cut by 8 and 59, respectively, and the drive signal S of the A liquid crystal 40 and the B liquid crystal 41 is thereby cut.
Generate S1 and SS2.

Specifically, as shown in FIG. 9, the demodulation circuit 42 is composed of only active elements that do not require a power source,
As a result, in the optical pickup 5, when the drive signals S1 to S4 are multiplexed and transmitted in this way, the drive signals SS1 and SS2 can be separated without supplying power.

That is, the demodulation circuit 42 has drive signals S11 and S across the series circuit of the resistor R1 and the diode D1.
12 is provided, and the series circuit of the resistor R1 and the diode D1 constitutes a first detection circuit for detecting the drive signal of the B liquid crystal 41 (FIG. 7 (D)). Further, drive signals S11 and S12 are similarly applied to both ends of the series circuit of the diode D2 and the resistor R2, which have no reverse connection of the diodes, and the series circuit of the resistor R3 and the diode D2 causes the A liquid crystal
A second detection circuit that detects a drive signal of 0 is configured.

Further, in the demodulation circuit 42, the capacitor C1 and the resistor R2 form a high pass filter 59, while the capacitor C2 and the resistor R4 form a high pass filter 58.

(1-2) Operation of the First Embodiment With the above configuration, the optical disk device 1 (see FIG.
2), the light amount of the laser beam L1 emitted from the optical pickup 5 is intermittently raised, and desired data is recorded on the optical disc 2. Also optical pickup 5
The matrix circuit 6 processes the received light of the return light detected in step S6 to obtain a reproduction signal RF.
The data recorded on the optical disc 2 is reproduced by the signal processing of F.

In the optical disc apparatus 1 thus accessed, the reproduction signal RF of the embossed pit or recording mark which is accessed immediately after the optical disc 2 is loaded, for example.
Accordingly, the jitter amount is detected by the jitter detection circuit 7, and the controller 8 calculates the correction amount of aberration based on the detection result. Further, a pair of drive signals S1 and S3 having a predetermined signal level are generated by this correction amount.

Further, in the optical disk device 1, the servo circuit 4 drives the drive signal S for tracking control based on the tracking error signal TE and the focus error signal FE.
0, a drive signal S4 for focus control is generated. In the optical disc device 1, these drive signals S1 to S4 are
In the transmitter 10, the signals are multiplexed and transmitted to the optical pickup 5, and the actuator 2 in the optical pickup 5 is transmitted.
On the movable target side of No. 1, these multiplexed drive signals are separated and the actuator 21 and the aberration correction mechanism 16 are driven.

As a result, in the optical disk device 1, these drive signals are multiplexed and transmitted, and separated and processed on the movable target side of the actuator 21 to transmit the conventional drive signals for tracking control and focus control. These drive signals can be supplied to the movable object of the optical pickup 5 by the same number of paths as the paths. Therefore, in the optical pickup 5, the objective lens 17 and the aberration correction mechanism 16 can be integrally held by the actuator 21 and moved without newly providing such a drive signal supply path. It is possible to effectively avoid deterioration of various characteristics due to holding the correction mechanism 16 and the objective lens 17 separately. That is, the objective lens 17
The optical axis of the objective lens 17 and the optical axis of the aberration correction mechanism 16 can be made to coincide with each other by moving the lens and the aberration correction mechanism 16 integrally. Further, it is possible to reduce individual differences between the optical pickups 5 as compared with the case where the objective lens 17 and the aberration correction mechanism 16 are separately mounted, and as a result, it is possible to manufacture an optical pickup with high accuracy and less variation. You can

Since it is not necessary to newly increase the number of signal supply lines in this way, the overall shape can be made smaller and lighter, and the deterioration of the movable characteristics of the actuator due to the newly provided signal supply lines can be effectively avoided. be able to.

That is, in this optical disk device 1,
In the optical pickup 5 (FIGS. 4 and 5), one end of each suspension 25 is held by a terminal 27 held by a suspension base 26 that is a fixed side of the actuator, and the objective lens 17,
A movable object is held by the aberration correction mechanism 16 and the like. The magnet 33 is held on the fixed side, and the tracking coil 30 and the focus coil 31 are arranged on the movable side. As a result, in the optical disk device 1, the objective lens 17
The aberration correction mechanism 16 can be integrally moved to effectively avoid coma and the like.

The aberration correction mechanism 16 constructed in this way is also provided.
In FIG. 6 (FIG. 6), glass substrates 16A, 16B and 16C each having electrodes are formed by laminating a liquid crystal in between, and a central glass substrate 16B is formed in a large size. The flexible wiring board 39 is arranged in the formed part. In the optical pickup 5,
A demodulation circuit 42 for separating the multiplexed drive signals is arranged on the flexible wiring board 39, and the flexible wiring board 39 is used as a lead wire processing unit for the tracking coil 30 and the focus coil 31. As a result, in the optical disc device 1, the demodulation circuit 42 is arranged by effectively utilizing the limited space of the optical pickup 5, and further the tracking coil 30 and the focus coil 31 are arranged.
The connection work and the like can be simplified.

In this way, when the drive signals S1 to S4 are multiplexed and transmitted, in the optical disk device 1 (FIG. 1), the rectangular wave signal generating circuit 9 has a rectangular shape with a sufficient duty ratio of 50%. The wave signal S2 is generated, and by the drive signals S1 and S3 of the aberration correction mechanism 16,
The positive side amplitude and the negative side amplitude of this rectangular wave signal are limited by the limiter 45, respectively. Further, the differential amplifier 46 generates an in-phase in-phase output S6 and an anti-phase anti-phase output S7 with respect to the output signal of the limiter 45.

In the optical disc device 1, the adder circuit 48 and the drive circuits 49 and 50 drive the tracking control drive signal S.
A pair of lines used for transmission of 0 is commonly biased by the in-phase output S6, whereby one drive signal S1 of the aberration correction mechanism 16 is multiplexed with the drive signal S0 for tracking control and transmitted. . Similarly, the pair of lines used for transmission of the drive signal S4 for focus control by the adder circuit 53 and the drive circuits 54 and 55 has an anti-phase output S7.
Is commonly biased by this, and thereby the remaining drive signal S3 of the aberration correction mechanism 16 is multiplexed with the drive signal S4 for focus control and transmitted.

In the optical disk device 1, these lines are guided to the flexible wiring board 39 via the terminals 27 and the suspensions 25, and the commonly biased lines are connected to the corresponding tracking coil 30 and focus coil 31, respectively. As a result, the tracking coil 30 and the focus coil 31 can be driven by the tracking control and focus control drive signals S0 and S4, respectively, without being affected by the drive signals S1 and S3 of the aberration correction mechanism 16. .

On the other hand, in the optical disk device 1, in the demodulation circuit 42 (FIGS. 8 and 9), the potential difference between the lines which is simply biased by the in-phase output S6 and the anti-phase output S7 reverses the diodes D1 and D2. It is detected by the first and second detection circuits arranged in the direction, and the positive side amplitude value and the negative side amplitude value set by the limiter 45 are thereby reproduced. Further, the direct current level is cut by the high-pass filter circuit, and the A liquid crystal 40 and the B liquid crystal 41 are driven by the output of the high pass filter circuit, respectively, whereby the wavefront of the laser beam L1 passing through the A liquid crystal 40 and the B liquid crystal 41 is corrected. It is possible to correct the aberration.

(1-3) Effects of the First Embodiment According to the above configuration, the aberration correction mechanism is transmitted to the liquid crystal etc. by multiplexing and transmitting the drive signal of the actuator and the drive signal of the aberration correction mechanism. Even in the case of the above configuration, the optical pickup can be simplified and downsized, and further various characteristic deteriorations can be prevented.

That is, by integrally holding the objective lens and the aberration correction mechanism, it is possible to move the objective lens and the aberration correction mechanism with their optical axes aligned with each other, and to prevent deterioration of characteristics due to coma aberration and the like. can do. Further, compared to the case where the objective lens and the aberration correction mechanism are separately mounted, it is possible to reduce the difference between the individuals, and accordingly, it is possible to manufacture an optical pickup with high accuracy and less variation. In addition, the pickup structure has been made smaller and lighter,
The requirement for high-speed response can be satisfied. Further, since the increase of the transmission line can be prevented, the spring coefficient viewed from the actuator can be suppressed to a necessary minimum, and sufficient sensitivity (voltage vs. propulsion force) can be obtained even if the number of windings of the actuator is reduced.

Further, by compensating the wavefront of the laser beam by constructing this aberration correction mechanism with a liquid crystal, it is possible to prevent a significant increase in the mass of the movable object in the optical pickup, and the optical pickup can be miniaturized accordingly. , Can be made lighter.

In the actuator, a movable object is movably held by a suspension, which is a spring, and a transmission signal is transmitted to the movable object via the spring, so that the movable object holding member serves as a signal transmission path. It can be shared and the overall configuration can be simplified. In this way, in practice, two sets of suspensions for tracking control and focus control are used to transmit the drive signal for the actuator and the drive signal for the aberration correction mechanism, and a total of 4
The book suspension can transmit these signals. This makes it possible to maintain an optimal balance with respect to skew.

Further, a pair of lines used for transmission of the drive signal of the actuator are commonly biased by the rectangular wave signal whose amplitude is limited by the drive signal of the aberration correction mechanism, whereby the drive signal of the actuator and the drive of the aberration correction mechanism are driven. By multiplexing the signals, these drive signals can be separated with a simple configuration and without providing an active element, and this also makes it possible to reduce the size and weight of the optical pickup.

That is, on the demodulation side, the bias common to the pair of lines is detected by the detection circuit to separate the drive signal of the aberration correction mechanism, so that the drive signal is separated by a simple circuit configuration using only passive elements. be able to.

That is, by forming the demodulation circuit with only passive elements, it is possible to omit the securing of a power source required when using active elements, which also simplifies the structure of the optical pickup and reduces the size of the optical pickup. Can be converted.

By concretely configuring the detection circuit with a diode detection circuit, the demodulation circuit can be configured with a simple configuration.

(2) Second Embodiment FIG. 10 is a block diagram showing a transmitting section applied to an optical disk device according to the second embodiment of the present invention. The optical disc device according to this embodiment has the same configuration as the optical disc device according to the first embodiment, except that the configuration of the transmission unit 60 is different. This transmitter 6
0, the same components as those of the transmission unit 10 of the optical disc device 1 are denoted by the corresponding reference numerals, and duplicate description will be omitted.

In the transmitter 60, the differential amplifier 4
The in-phase output S6 and the anti-phase output S7 of 6 are output only to the drive circuits 50 and 55, respectively. In the transmitter 60, the current detectors 61 and 62 detect the currents flowing in the tracking coil and the focus coil, respectively, and output a current detection signal whose signal level changes according to each current value. The transmission unit 60 corrects the signal levels of the drive signals S0 and S4 by the corresponding current detection signals by the subtraction circuits 63 and 64, and then supplies them to the drive circuits 49 and 54 via the amplifier circuits 65 and 66, respectively.

As a result, in the transmitter 60, the actuator 21 is driven by current feedback, and even when the in-phase output S6 and the anti-phase output S7 are supplied to only one of the pair of lines, respectively, 1 each
The pair of lines are commonly biased so that the tracking coil 30 and the focus coil 31 can be reliably driven by the drive signals S0 and S4, respectively.

As shown in FIG. 10, the actuator 21
Are driven by current feedback to supply the in-phase output S6 and the anti-phase output S7 respectively to only one of the pair of lines, the same effect as in the first embodiment can be obtained. You can

(3) Third Embodiment FIG. 11 is a block diagram showing a transmission section applied to an optical disk device according to a third embodiment of the present invention. The optical disc device according to this embodiment has the same configuration as the optical disc device according to the first embodiment, except that the configuration of the transmitting unit 70 is different. Further, in the transmitting unit 70, the same configurations as those of the transmitting units 10 and 60 described above are denoted by the corresponding reference numerals, and the duplicated description will be omitted.

In this embodiment, as in the transmitting section 10 according to the first embodiment, each pair of lines is commonly biased by the in-phase output S6 and the anti-phase output S7, and the second embodiment is further implemented. The actuator 21 is driven by current feedback as in the transmitting unit 60 according to the above embodiment.

As shown in FIG. 11, similarly to the transmitting section 10 according to the first embodiment, each pair of lines is commonly biased by the in-phase output S6 and the anti-phase output S7, and the second embodiment is performed. If the actuator 21 is driven by current feedback as in the transmitting unit 60 according to the above embodiment, the frequency characteristic in driving the actuator 21 can be improved in addition to the effect of the first embodiment.

(4) Fourth Embodiment FIG. 12 is a block diagram showing a transmission section applied to an optical disk device according to a fourth embodiment of the present invention. The optical disc device according to this embodiment has the same configuration as the optical disc device according to the first embodiment, except that the configuration of the transmitting unit 75 is different. Further, in this transmitting unit 75, the same configuration as that of the transmitting unit 10 described above is
Corresponding reference numerals are given and shown, and duplicate explanations are omitted.

In the transmitter 75, the differential amplifier 4
The in-phase output S6 and the anti-phase output S7 output from 6 are input to the amplifier circuits 77 and 78. Also, drive signals S0 and S
4 is input to the amplifier circuits 76 and 79. The transmitter 75
The amplifier circuits 76 and 79 are current output type amplifier circuits, and the amplifier circuits 77 and 78 are voltage output side amplifier circuits. As a result, similar to the first embodiment,
Each pair of lines is biased by the in-phase output S6 and the anti-phase output S7, and the drive signals S0 to S4 are multiplexed and transmitted.

As shown in FIG. 12, driven by a current output type amplifier circuit, each pair of lines is biased by an in-phase output S6 and an anti-phase output S7, respectively, and drive signals S0 to S0.
Even if S4 is multiplexed and transmitted, the same effect as that of the first embodiment can be obtained.

(5) Fifth Embodiment FIG. 13 is a block diagram showing a transmitting section applied to an optical disk device according to the fifth embodiment of the present invention. The optical disc device according to this embodiment has the same configuration as the optical disc device according to the first embodiment, except that the configuration of the transmission unit 80 is different. In addition, in the transmitting unit 80, the same configuration as the transmitting unit 10 described above is
Corresponding reference numerals are given and shown, and duplicate explanations are omitted.

In the transmitter 80, the adder circuit 81
And 82, the bias voltage VB is applied to the in-phase output S6 and the anti-phase output S7 output from the differential amplifier 46, respectively.
Are added, and then output to the drive circuits 49, 59, 54 and 55. As a result, in this embodiment, the drive circuits 49, 59, 54 and 55 can be constituted by a single power source.

According to the configuration shown in FIG. 13, the in-phase output S6 and the anti-phase output S7 are biased to drive circuits 49, 59 and 5.
By outputting to 4 and 55, drive circuits 49, 59
And 54 and 55 can be configured by a single power source, and the whole shape can be simplified in addition to the effect of the first embodiment.

(6) Sixth Embodiment FIG. 14 is a block diagram showing a transmission section applied to an optical disk device according to the sixth embodiment of the present invention. The optical disc device according to this embodiment has the same configuration as the optical disc device according to the first embodiment, except that the configuration of the transmission unit 80 is different. In addition, in the transmitting unit 80, the same configuration as the transmitting unit 10 described above is
Corresponding reference numerals are given and shown, and duplicate explanations are omitted.

In the transmitting section 90, the adding circuit 48
Thus, the drive signal S0 is added to the in-phase output S6, and the subtraction circuit 91 subtracts the drive signal S0 from the in-phase output S6. As a result, in the transmitter 90, the in-phase output S6 is biased to the positive side and the negative side by the drive signal S0, and is output via the drive circuits 49 and 50, respectively. As a result, in the transmitter 90, the tracking coil 30 is driven in the differential mode, and the pair of lines used for driving in the differential mode is biased by the in-phase output S6.

Similarly, in the transmitter 90, the adder circuit 5
The driving signal S4 is added to the negative phase output S7 by 3 and the driving signal S4 is subtracted from the negative phase output S7 by the subtracting circuit 93. As a result, in the transmitter 90, the reverse phase output S7
Is biased to the positive side and the negative side by the drive signal S4, and is output via the drive circuits 54 and 55. As a result, in the transmitter 90, the focus coil 31 is driven in the differential mode, and the pair of lines used for driving in the differential mode is biased by the antiphase output S7.

As a result, in this embodiment, the drive signals S0 and S4 for tracking control and focus control are transmitted in the differential mode, and in response to this, the demodulation circuit 95 responds to these drive signals S10 to S10. From S14, drive signals SS1 and SS of the A liquid crystal 96 and the B liquid crystal 97
Generates 2. The A liquid crystal 96 and the B liquid crystal 97 are the same as the A liquid crystal 4 except that transparent electrodes formed on both surfaces of the glass substrate 16B are insulated and can be driven independently.
0 and B liquid crystal 41 have the same configuration.

That is, FIG. 15 is a connection diagram showing the demodulation circuit 95. The demodulation circuit 95 receives drive signals S10 and S11 obtained by transmitting the drive signal S1 for tracking control in the differential mode at both ends of the series circuit of the resistors R1 and R2, and similarly, for focus control in the differential mode. The drive signals S12 and S13 obtained by transmitting the drive signal S4 are received at both ends of the series circuit of the resistors R7 and R8.
The resistors R1 and R2 and the resistors R7 and R8 are set to substantially the same resistance value, whereby the demodulation circuit 9
5 is the drive signals S1 and S transmitted in the differential mode
4, an almost midpoint potential is generated, and the drive signals SS1 and SS2 are reproduced from the midpoint potential in the same manner as the demodulation circuit 42 according to the first embodiment.

The demodulation circuit 95 connects the connection midpoint of the resistors R1 and R2 and the connection midpoint of the resistors R7 and R8 to the diode D.
1 connected to form a detection circuit, and a capacitor C
A high-pass filter circuit is constructed by connecting a series circuit of 1 and the resistor R5 to the midpoint of these connections. As a result, the demodulation circuit 95 outputs the output across the resistor R5 as the drive signal SS1.

Similarly, drive signals S10 and S1
1 is received at both ends of the series circuit of the resistors R3 and R4, and the drive signals S12 and S13 are received at both ends of the series circuit of the resistors R9 and R10. Furthermore, the connection midpoint of the resistors R3 and R4,
A detection circuit is configured by connecting the connection middle point of the resistors R9 and R10 with a diode D2 arranged in the opposite direction to the diode D1, and a series circuit formed by the capacitor C2 and the resistor R6 is connected to these connection middle points to make a high pass. Configure a filter circuit. As a result, the demodulation circuit 95 causes the resistor R6 to
The outputs of both ends of are output as the drive signal SS2.

Even when the actuator drive signal is transmitted in the differential mode as in the configuration of FIGS. 14 and 15, the same effect as that of the first embodiment can be obtained.

(7) Seventh Embodiment FIG. 16 is a block diagram showing, together with the peripheral structure, a transmitter applied to an optical disk device according to a seventh embodiment of the present invention, in comparison with FIG. is there. The optical disk device according to this embodiment has the same structure as the optical disk device according to the first embodiment except that the structure shown in FIG. 16 is applied. In the structure shown in FIG. 16, the same structures as those described above in the first embodiment are designated by the corresponding reference numerals, and the duplicated description will be omitted.

In the transmitting section 100 according to this embodiment, instead of the rectangular wave signal S2, a rectangular wave signal S9 having a frequency sufficiently higher than that of the rectangular wave signal S2 and a duty ratio of 50% is sent to the limiter 45. Is entered. Here, the frequency of the rectangular wave signal S9 is set to a frequency at which the rectangular wave signal S2 can be easily band-separated by using a bandpass filter having a simple configuration. As a result, in this embodiment, the amplitude of the rectangular wave signal S9 that is a burst signal is limited by the signal levels VUP and VLO of the drive signals S1 and S3 of the aberration correction mechanism.

The multiplexer 101 is composed of a switch circuit which intermittently outputs the output signal of the limiter 45 to the differential amplifier 46 according to the signal level of the drive signal S2.

As a result, in the transmitting section 100 according to this embodiment, as shown in FIGS. 17A and 17B, the positive side and the negative side by the signal levels VUP and VLO of the drive signals S1 and S3 of the aberration correction mechanism. A burst-shaped signal whose negative-side amplitude is limited is intermittently input to the differential amplifier 46 by the drive signal S2 having a duty ratio of 50 [%], and the intermittent burst signal is applied to the drive signal S0 for tracking control. , And is multiplexed with the drive signal S4 for focus control and transmitted. Note that this FIG.
(A) and (B) are signal waveforms of the anti-phase output S7 output from the differential amplifier 46, and the period T1 is the rectangular wave signal S.
The period T2 is the period of the rectangular wave signal S9.

In the optical pickup 5, the demodulation circuit 102 demodulates the drive signals SS1 and SS2 of the aberration correction mechanism thus multiplexed and transmitted.

FIG. 18 is a block diagram showing the demodulation circuit 102. The demodulation circuit 102 uses the drive signals S11 to S13.
Among them, the drive signals S11 and S12 on the side which are simply biased by the in-phase component S6 and the anti-phase component S7 are input to the detection circuit 107, where the peaks corresponding to the positive limit value and the negative limit value in the limiter 45 are peaked. Positive side detection signal SA1 and negative side detection signal SA2 having values are generated (FIG. 17 (C2) and (C1)).

Bandpass filter (BPF) 1 that follows again
09A and 109B remove the signal component of the rectangular wave signal S9 from the positive-side detection signal SA1 and the negative-side detection signal SA2, and generate drive signals S11 and S12 (FIG. 1).
7 (D2) and (D1)).

FIG. 19 is a connection diagram showing a specific structure of the demodulation circuit 102. In this demodulation circuit 102,
The detection circuit 107 is composed of the resistor R1 and the diode D1. Further, one bandpass filter 109A is configured by the series connection of the series circuit including the resistor R2 and the capacitor C1 and the parallel circuit including the resistor R3 and the capacitor C2, and the series circuit including the resistor R5 and the capacitor C4 and the parallel circuit including the resistor R4 and the capacitor C3. The other bandpass filter 109B is configured by series connection with the circuit.

According to the configuration shown in FIG. 16, even if the drive signal of the actuator and the drive signal of the aberration correction mechanism are multiplexed and transmitted by superimposing the burst-like signals intermittently, the first embodiment is adopted. The same effect as the form can be obtained.

The frequencies of the rectangular wave signals S9 and S2 are 1 [MHz] and 2 [kHz], respectively, and the low-pass cutoff frequencies of the bandpass filters 109A and 109B.
High cutoff frequency is 3.4 [kHz],
When an experiment was performed with the frequency set to 16 [kHz], tracking control and focus control could be performed with sufficient frequency characteristics and gain, and the aberration correction mechanism could be driven.

(8) Eighth Embodiment FIG. 20 illustrates the operation of the transmission section and the optical pickup applied to the optical disk device according to the eighth embodiment of the present invention by comparison with FIG. It is a signal waveform diagram to provide.

In the optical disk device according to this embodiment, the limiter 45 controls the amplitude value and the duty ratio of the rectangular wave signal S9 instead of limiting the positive amplitude value and the negative amplitude value of the rectangular wave signal S9. , Drive signal S1
16 to 19 except that 1 and S12 are multiplexed.
Since the optical disk device has the same configuration as the optical disc device according to the seventh embodiment described above, the configuration of FIG. 16 will be used here for description.

In the transmission section 100 of this optical disk device, the limiter 45 limits the amplitude value of the rectangular wave signal S9 by the drive signal S1 of the aberration correction mechanism and outputs it (FIG. 2).
0 (A) and (B)). Regarding the limitation of the amplitude value, in relation to the seventh embodiment described above, the positive side amplitude value VUP is set so as to change according to the signal level of the drive signal S1. The negative side amplitude value VLO is set so as to match VUP.

The transmission section 100, in accordance with the signal level of the drive signal S2 with respect to the drive signal S1 of this aberration correction mechanism,
The duty ratio (D = T3 / T2) of the rectangular wave signal S9 is set. That is, when the signal level of the drive signal S1 and the signal level of the drive signal S2 are equal, the rectangular wave signal S9
Has a duty ratio of 50%. On the other hand, the drive signal S2 with respect to the signal level of the drive signal S1
When the signal level of increases, the period T which rises to the positive side
When the duty ratio is controlled so that the period T3 of falling to the negative side becomes longer than that of 2, and conversely, the signal level of the drive signal S2 decreases with respect to the signal level of the drive signal S1. The duty ratio is controlled so that the period T3 of falling to the negative side is shorter than the period T2 of rising to the positive side.

As a result, in this embodiment, the bandpass filter 109 is detected by the optical pickup 5 side.
When the band is limited by A and 109B, the same drive signals SS1 and SS2 as in the case where the positive side amplitude value and the negative side amplitude value of the rectangular wave signal S9 are limited can be generated in the seventh embodiment. (Fig. 20 (C
1) to (D2)).

According to the configuration shown in FIG. 20, by intermittently superimposing the burst-like signal, the drive signal of the actuator and the drive signal of the aberration correction mechanism are multiplexed and transmitted, and the amplitude of the burst-like signal is transmitted. Even if the drive signals S11 and S12 are multiplexed by controlling the value and the duty ratio, the same effect as that of the first embodiment can be obtained.

The frequencies of the rectangular wave signals S9 and S2 are 1 [MHz] and 2 [kHz], respectively, the low-pass cutoff frequencies of the bandpass filters 109A and 109B,
High cutoff frequency is 3.4 [kHz],
When an experiment was performed with the frequency set to 16 [kHz], tracking control and focus control could be performed with sufficient frequency characteristics and gain, and the aberration correction mechanism could be driven.

Incidentally, instead of the drive signal S1, the drive signal S3
Even if the amplitude of the rectangular wave signal S9 is controlled by
The same effect can be obtained.

(9) Other Embodiments In the above-described embodiments, the case where the demodulation circuit is configured by only passive elements has been described, but the present invention is not limited to this, and active elements may be used as necessary. You may make it comprise a demodulation circuit. In this case, it is conceivable that the power source is further superimposed on the signal line for transmission, and it is conceivable to demodulate the drive signal by various methods instead of demodulating the drive signal by diode detection. In addition, various methods can be widely applied to the multiplexing method.

Further, in the above-described first embodiment and the like, the case where the positive side and the negative side detection circuits are respectively provided in the demodulation circuit has been described, but the present invention is not limited to this, and comparison with FIG. Therefore, as shown in FIG. 21, these detection circuits may be shared. By doing so, the configuration can be further simplified.

In the above embodiment, the case where the transparent electrode is formed concentrically to correct the wavefront of the laser beam about the optical axis in the aberration correction mechanism has been described. The present invention is not limited to this, and can be widely applied to various wavefront corrections, for example, when correcting a wavefront in the inner and outer circumference directions of an optical disc.

Further, in the above-described embodiment, the case where the aberration correction mechanism is constituted by one set of liquid crystal has been described, but the present invention is not limited to this, and the aberration correction mechanism is constituted by the liquid crystal by further increasing the number. Drive signal is transmitted by
Furthermore, the aberration correction mechanism can be configured by various correction mechanisms other than the liquid crystal, and can be widely applied to the case of transmitting a drive signal.

In the above embodiment, the case where the optical pickup is constructed by a so-called cantilever structure with four suspensions has been described, but the present invention is not limited to this, and the optical pickup is arranged on both sides of the optical system. The present invention can be widely applied to a case where an optical pickup is configured by various holding mechanisms, such as a case where an optical system is movably held from both sides by a base material.

In the above embodiment, the case where the transmitter is arranged outside the optical pickup and in the optical disk device has been described, but the present invention is not limited to this. For example, the transmitter is arranged on the fixed side of the optical pickup. You may do it.

Further, in the above-mentioned embodiments, the case where the amount of jitter is detected to generate the drive signal of the aberration correction mechanism has been described, but the present invention is not limited to this. For example, the reproduction signal RF is envelope-detected. Reproduction signal RF PP
The present invention can be widely applied to the case where the aberration correction mechanism is driven by various criteria, such as the case where the value is detected and the aberration correction mechanism is driven based on the detection result. Further, instead of the processing based on the reproduction result of such an optical disc, when the drive signal is generated by various methods, for example, when the drive signal of the aberration correction mechanism is generated by the information recorded in advance on the optical disc. It can be widely applied.

In the seventh and eighth embodiments, the focus coil similar to that of the first embodiment,
Although the focus control and the tracking control are performed by driving the tracking coil, the present invention is not limited to this, and the focus coils described in the second to sixth embodiments are not limited to this and also in the case of multiplexing by a burst signal. The tracking coil driving method can be widely applied.

Further, in the above-described embodiment, the case where a so-called open magnet type actuator in which a tracking coil and a focus coil are arranged between opposing magnets is applied is described, but the present invention is not limited to this, and each magnet is not limited to this. The present invention can be widely applied to the case of applying a closed magnetic type actuator having a structure in which the yoke is arranged so as to face each other.

Further, in the above-mentioned embodiment, the case where the spherical aberration due to the error of the thickness of the light transmitting layer or the like is corrected by the aberration correction mechanism has been described. Aberration, astigmatism, etc.
It can be widely applied when various aberrations are corrected by the aberration correction mechanism.

In the above embodiment, the case of accessing the phase change type optical disk has been described.
The present invention is not limited to this, and can be widely applied to optical pickups and optical disk devices that access various optical disks.

[0123]

As described above, according to the present invention, the optical pickup is used even when the aberration correction mechanism is composed of liquid crystal or the like by multiplexing and transmitting the drive signal of the actuator and the drive signal of the aberration correction mechanism. Can be simplified and downsized, and various characteristic deteriorations can be prevented.

[Brief description of drawings]

FIG. 1 is a block diagram showing a transmission unit and an optical pickup applied to an optical disc device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing an optical disk device according to the first embodiment of the present invention.

FIG. 3 is a side view showing an optical system of an optical pickup applied to the optical disc device of FIG.

FIG. 4 is a perspective view showing a part of the actuator of FIG.

5 is a plan view and a perspective view of FIG. 4. FIG.

6 is an exploded perspective view for explaining an aberration correction mechanism applied to the optical pickup of FIG.

FIG. 7 is a signal waveform diagram for explaining the transmission of a drive signal.

8 is a block diagram showing the demodulation circuit of FIG. 1. FIG.

9 is a connection diagram showing details of the demodulation circuit in FIG.

FIG. 10 is a block diagram showing a transmitting unit applied to an optical disc device according to a second embodiment of the present invention.

FIG. 11 is a block diagram showing a transmitting unit applied to an optical disc device according to a third embodiment of the present invention.

FIG. 12 is a block diagram showing a transmission section applied to an optical disc device according to a fourth embodiment of the present invention.

FIG. 13 is a block diagram showing a transmitting unit applied to an optical disc device according to a fifth embodiment of the present invention.

FIG. 14 is a block diagram showing a transmitter and an optical pickup applied to an optical disc device according to a sixth embodiment of the present invention.

FIG. 15 is a connection diagram showing the demodulation circuit of FIG.

FIG. 16 is a block diagram showing a transmitter and an optical pickup applied to an optical disc device according to a seventh embodiment of the present invention.

FIG. 17 is a signal waveform diagram for explaining the transmission of a drive signal.

FIG. 18 is a block diagram showing the demodulation circuit of FIG. 16.

19 is a connection diagram showing details of the demodulation circuit in FIG. 18. FIG.

FIG. 20 is a diagram showing a transmitter and an optical pickup applied to an optical disc device according to an eighth embodiment of the present invention.
FIG. 6 is a signal waveform diagram for explaining transmission of a drive signal.

FIG. 21 is a connection diagram showing a demodulation circuit according to another embodiment.

[Explanation of symbols]

1 ... Optical disk device, 2 ... Optical disk, 5 ... Optical pickup, 9 ... Rectangular wave signal generation circuit, 10, 60,
70, 75, 80, 90, 100 ... Transmitter, 16 ...
Aberration correction mechanism, 17 ... Objective lens, 21 ... Actuator, 25 ... Suspension, 30 ... Tracking coil, 31 ... Focus coil, 39 ... Flexible wiring board, 42, 95, 102, 106 ... Demodulation circuit , 101 ... Multiplexer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Gakuji Hashimoto             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation F-term (reference) 5D118 AA01 AA03 BA01 DC03 EE00                 5D119 AA01 AA03 BA01 EA01 EC01                       JA09 JA43                 5D789 AA01 AA03 BA01 EA01 EC01                       JA09 JA43

Claims (22)

[Claims] 1. A method of driving an optical pickup in which an objective lens is moved by an actuator and at least tracking control and focus control are performed, and an aberration correction mechanism for correcting a wavefront of a laser beam incident on the objective lens is integrated with the objective lens. And the transmission unit generates a transmission signal by multiplexing the drive signal of the actuator and the drive signal of the aberration correction mechanism by the transmission unit, and transmits the transmission signal to the movable target side of the actuator. In the demodulation circuit on the side, a drive signal for the actuator and a drive signal for the aberration correction mechanism are separated from the transmission signal. 2. The method of driving an optical pickup according to claim 1, wherein the aberration correction mechanism corrects the wavefront of the laser beam with liquid crystal. 3. The actuator holds the movable object movably by a plurality of springs, and transmits the transmission signal to the movable object side via the springs. A method for driving the described optical pickup. 4. The actuator is configured to commonly bias a pair of lines used for transmission of a drive signal of the actuator by a rectangular wave signal whose amplitude is limited by a drive signal of the aberration correction mechanism, thereby the actuator 2. The method of driving an optical pickup according to claim 1, wherein the drive signal of 1) and the drive signal of the aberration correction mechanism are multiplexed. 5. The optical pickup according to claim 4, wherein the demodulation circuit detects a bias common to the pair of lines by a detection circuit to separate the drive signal of the aberration correction mechanism. Driving method. 6. The method of driving an optical pickup according to claim 1, wherein the demodulation circuit is formed by only passive elements. 7. The method of driving an optical pickup according to claim 5, wherein the detection circuit is a diode detection circuit. 8. The drive signal of the aberration correction mechanism is formed by first and second drive signals, and the transmitter is configured to transmit the first drive signal to the drive signal of the actuator for tracking control. By limiting the positive side amplitude value or the negative side amplitude value of the rectangular wave signal and biasing the corresponding pair of lines in common, thereby multiplexing the first drive signal, and By limiting the negative side amplitude value or the positive side amplitude value of the rectangular wave signal by the second drive signal with respect to the drive signal of the actuator and biasing the corresponding pair of lines in common, 5. The method of driving an optical pickup according to claim 4, wherein the two drive signals are multiplexed. 9. An optical pickup capable of at least tracking control and focus control by moving an objective lens by an actuator, and an aberration correcting mechanism which is held integrally with the objective lens and corrects a wavefront of a laser beam incident on the objective lens. From the transmission signal transmitted from the fixed side of the actuator, which is movably held integrally with the objective lens,
An optical pickup having a demodulation circuit for separating a drive signal of the actuator and a drive signal of the aberration correction mechanism. 10. The optical pickup according to claim 9, wherein the aberration correction mechanism corrects the wavefront of the laser beam with a liquid crystal. 11. The actuator according to claim 9, wherein the actuator holds a movable object movably by a plurality of springs, and the demodulation circuit inputs the transmission signal via the springs. Optical pickup. 12. The demodulation circuit separates a drive signal of the aberration correction mechanism by detecting a bias common to a pair of lines used for transmission of the transmission signal by a detection circuit. The optical pickup according to item 9. 13. The optical pickup according to claim 9, wherein the demodulation circuit is formed by only passive elements. 14. The detection circuit is a diode detection circuit.
Optical pickup described in. 15. An optical disk device for controlling at least tracking control and focus control by moving an objective lens mounted on an optical pickup by an actuator, wherein a wavefront of a laser beam which is held integrally with the objective lens and is incident on the objective lens. An aberration correction mechanism that corrects a drive signal of the actuator, a drive signal generation circuit that generates a drive signal of the aberration correction mechanism, a drive signal of the actuator, and a transmission signal by multiplexing the drive signal of the aberration correction mechanism. And a transmission unit that transmits the transmission signal to the movable target side of the actuator, and the objective lens is movably held integrally, and the transmission signal is used to drive the actuator drive signal and the aberration correction. And a demodulation circuit for separating the drive signal of the mechanism. Disk device. 16. The optical disk device according to claim 15, wherein the aberration correction mechanism corrects the wavefront of the laser beam with a liquid crystal. 17. The actuator according to claim 15, wherein the actuator holds a movable object movably by a plurality of springs, and transmits the transmission signal to the movable object side via the springs. Optical disk device. 18. The actuator comprises biasing a pair of lines for transmission of a drive signal of the actuator in common with a rectangular wave signal whose amplitude is limited by a drive signal of the aberration correction mechanism, thereby the actuator 16. The optical disk device according to claim 15, wherein the drive signal of 1) and the drive signal of the aberration correction mechanism are multiplexed. 19. The optical disk device according to claim 18, wherein the demodulation circuit detects a bias common to the pair of lines by a detection circuit to separate the drive signal of the aberration correction mechanism. 20. The optical disk device according to claim 15, wherein the demodulation circuit is formed by only passive elements. 21. The detection circuit is a diode detection circuit.
The optical disk device described in 1. 22. The drive signal of the aberration correction mechanism is formed by first and second drive signals, and the transmitter is configured to transmit the first drive signal to the drive signal of the actuator for tracking control. By limiting the positive side amplitude value or the negative side amplitude value of the rectangular wave signal and biasing the corresponding pair of lines in common, thereby multiplexing the first drive signal, and By limiting the negative side amplitude value or the positive side amplitude value of the rectangular wave signal by the second drive signal with respect to the drive signal of the actuator and biasing the corresponding pair of lines in common, 19. The optical disk device according to claim 18, wherein the two drive signals are multiplexed.