JPH0793771A - Optical recording / reproducing device - Google Patents

Abstract

(57) [Summary] [Object] The present invention can widen the bandwidth of a tracking or focusing servo system circuit by using a current amplifying means such as a current mirror circuit by a current processing method capable of improving frequency characteristics and phase rotation characteristics. Provided is an optical recording / reproducing device which can be realized. The optical recording / reproducing apparatus of the present invention is an optical recording / reproducing apparatus for irradiating a light beam onto an optical recording medium to optically record / reproduce information, wherein the reflected light from the optical recording medium is received for focusing. And a sensor means for outputting a current signal for tracking, a current amplifying means for amplifying the current signal from the sensor means, and a servo signal for focusing and tracking based on the current amplified signal from the current amplifying means. At the same time, a servo means is provided for performing focusing and tracking control of the light beam with respect to the optical recording medium based on the servo signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording / reproducing device, and more particularly to an optical recording / reproducing device having an improved focus service circuit and tracking servo circuit.

[0002]

2. Description of the Related Art Conventionally, a servo system signal processing circuit for tracking and focusing in an optical recording / reproducing apparatus such as an optical disk apparatus, as shown in FIGS. 5 and 6, uses a photodetector PD for detecting reflected light from a recording medium. After converting the current signal from the current signal into a voltage signal by the current-voltage converter IV (actually, the differential operational amplifiers OP1 to OP4 etc.), the voltage signal is processed, and the servo system error signal is passed through the automatic gain control circuit AGC1. Was getting

By the way, in this type of optical disk apparatus, the focus and tracking servo bands are required to be improved in accordance with the increase in the number of disk revolutions, the increase in accuracy of seek operation, and the increase in speed, and during the high speed seek operation. However, it is necessary to detect the number of crossing tracks based on the track error signal.

Therefore, it is indispensable to widen the bandwidth of the servo system control circuit more than ever.

As described above, in the prior art, FIG. 5 and FIG.
As shown in FIG. 4, the output current of the photodetector PD as the servo position sensor is current-voltage converted by the differential operational amplifiers OP1 to OP4 and then voltage processed.

[0006]

However, the operational amplifier OP4 for performing the voltage processing is actually configured as shown in FIG. 7, and the current amplifier circuit 171 and the current-voltage converter 172 are composed. In the meantime, phase rotation tends to occur due to the influence of the stray capacitance CS and the mirror effect of the transistor used, and the band characteristic tends to deteriorate.

Reference numeral 170 in FIG. 7 is a voltage-current conversion circuit.

Therefore, in the conventional tracking / focusing servo system in the optical recording / reproducing apparatus, the phase rotation is suppressed and a wide-band circuit is constructed.
It was a disadvantage.

In addition, in such a voltage signal processing circuit, when the operating range of the signal is wide, naturally, a high power supply voltage must be supplied, which reduces the power supply voltage to the optical recording / reproducing apparatus. On the other hand, it was a problem.

Therefore, the present invention has been made in view of the above points, and it is possible to perform tracking or tracking by using a current amplifying means such as a current mirror circuit by a current processing method capable of improving frequency characteristics and phase rotation characteristics. It is an object of the present invention to provide an optical recording / reproducing device capable of realizing a wide band of a focusing servo system circuit.

[0011]

In order to solve the above-mentioned problems, according to the present invention, an optical recording / reproducing apparatus for irradiating a light beam onto an optical recording medium to optically record / reproduce information is provided. Sensor means for receiving reflected light from the sensor and outputting a current signal for focusing and tracking, current amplifying means for amplifying the current signal from the sensor means, and focusing based on the current amplified signal from the current amplifying means And a servo means for generating a servo signal for tracking and performing focusing and tracking control of the light beam with respect to the optical recording medium based on the servo signal. To be done.

Further, according to the present invention, in an optical recording / reproducing apparatus for irradiating a light beam on an optical recording medium to optically record / reproduce information, the reflected light from the optical recording medium is received to perform focusing and tracking. First to fourth photodiodes for outputting a current signal for use with the first and fourth photodiodes, and the current signals from the first to fourth photodiodes are amplified to obtain first and second current amplified signals. Outputting first to fourth current mirror circuits and focusing and tracking servo signals based on the respective first current amplified signals from the first to fourth current mirror circuits output second currents. An automatic gain control circuit for controlling by a signal for automatic gain control based on an amplified signal, and a servo signal from the automatic gain control circuit is current-voltage converted to the optical recording medium of the light beam. Optical recording and reproducing apparatus is provided which is characterized by comprising means for performing Okashingu and tracking control.

According to the present invention, in the optical recording / reproducing apparatus for irradiating the optical recording medium with a light beam to optically record / reproduce information, the reflected light from the optical recording medium is received to perform focusing and tracking. First to fourth photodiodes for outputting a current signal for use with the first and fourth photodiodes, and the current signals from the first to fourth photodiodes are amplified to obtain first and second current amplified signals. First to third transistors and first to third, respectively, for outputting
First to fourth current mirror circuits composed of the resistors and focusing and tracking servo signals based on the first current amplified signals from the first to fourth current mirror circuits. An automatic gain control circuit for controlling by a signal for automatic gain control based on a second current amplified signal, and a servo signal from the automatic gain control circuit is converted into current-voltage to focus the light beam on the optical recording medium. An optical recording / reproducing apparatus is provided, which comprises: and a means for performing tracking control.

Further, according to the present invention, in the optical recording / reproducing apparatus for irradiating the optical recording medium with a light beam to optically record / reproduce information, the reflected light from the optical recording medium is received to perform focusing and tracking. First to fourth photodiodes for outputting a current signal for use with the first and fourth photodiodes, and the current signals from the first to fourth photodiodes are amplified to obtain first and second current amplified signals. Outputting first to fourth current mirror circuits and focusing and tracking servo signals based on the respective first current amplified signals from the first to fourth current mirror circuits output second currents. An automatic gain control circuit having a four-quadrant multiplier function and composed of first to eighth transistors for controlling by a signal for automatic gain control based on an amplified signal, and the automatic gain control circuit A servo signal et current - optical recording and reproducing apparatus, characterized in that to voltage conversion and means for performing focusing and tracking control for the optical recording medium of the light beam.

Further, according to the present invention, in an optical recording / reproducing apparatus for irradiating a light beam on an optical recording medium to optically record / reproduce information, the reflected light from the optical recording medium is received to perform focusing and tracking. First to fourth photodiodes for outputting a current signal for use with the first and fourth photodiodes, and the current signals from the first to fourth photodiodes are amplified to obtain first and second current amplified signals. First to third transistors and first to third, respectively, for outputting
First to fourth current mirror circuits composed of the resistors and focusing and tracking servo signals based on the first current amplified signals from the first to fourth current mirror circuits. An automatic gain control circuit having a four-quadrant multiplier function and comprising first to eighth transistors for controlling by a signal for automatic gain control based on a second current amplification signal; An optical recording / reproducing apparatus is provided, comprising means for converting a servo signal from a control circuit into a current-voltage to perform focusing and tracking control of the light beam with respect to the optical recording medium.

[0016]

According to the above-mentioned solution means, the voltage signal processing circuit is reduced as much as possible by performing the current signal processing by using the current amplification means for amplifying the focusing and tracking current signals from the sensor means. Enables wide bandwidth of the system.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below with reference to the drawings.

First, a schematic structure of an optical recording / reproducing apparatus will be described with reference to FIG.

An optical disk 1 as a recording medium is placed on a turntable 2, and the turntable 2 is rotated by a spindle motor 3.

An optical head 5 is arranged on the back side of the optical disk 1 so as to face it.

Next, the internal structure of the optical head 5 for irradiating the optical disk 1 with laser light to write or read information will be described.

The semiconductor laser 11 outputs laser light on a beam.

This laser light is given to the objective lens 17 through the lens 13 and the half prism 15a.

The optical disc 1 is arranged on the focal point of the objective lens 17, and the spot-shaped laser light passing through the objective lens 17 is applied to the track surface of the optical disc 1.

The objective lens 17 is movably provided in each of a tracking direction which is a radial direction of the optical disc 1 and a focusing direction which is a direction perpendicular to the radial direction of the optical disc 1.

A focus coil 19 and a track coil 21 for moving the objective lens 17 are provided.

That is, by passing a current through the focus coil 19, the objective lens 17 is moved in the focusing direction according to this current value.

By passing a current through the track coil 21, the objective lens 17 is moved in the track direction according to the current value.

The laser light reflected by the track surface of the optical disk 1 is split into two directions by the half prism 15b.

One of these lights enters the condenser lens 25, and the other light enters the condenser lens 27.

A focus position sensor (photodetector) 29 is arranged on the focal point of the condenser lens 25, and the light condensed by the condenser lens 25 is imaged by the focus position sensor 29.

A track position sensor 31 is arranged on the focal point of the condenser lens 27, and the light condensed by the condenser lens 27 is imaged by the track position sensor (photodetector) 31.

In FIG. 1, BL is a bus line,
It is coupled to a control circuit 61 including a RAM 65, a CPU 63 and a ROM 67.

Further, 51 is a focusing control circuit 4.
5, an A / D converter coupled to the tracking control circuit 73 and the bus line BL.

Further, 53 is a focusing control circuit 4.
5, a tracking control circuit 73, a linear motor control circuit 77, and a D / A converter coupled to the bus line BL.

The control circuit 61 controls the entire optical recording / reproducing apparatus as described above.

Further, the A / D converter 51 and the D / A converter 53 are used for high speed search and seek.

The output current of the track position sensor 31 is connected to the tracking control circuit 73, and the tracking control circuit 73 outputs the output current from the track position sensor 31 by performing current-voltage conversion and generation of a difference signal.

The tracking control circuit 73 is connected to the track coil 21 via an amplifier 75 and outputs a signal corresponding to the amount of displacement in the track direction to the track coil 21.

The linear motor control circuit 77 is connected to the tracking control circuit 73, and the linear motor 79
And controls the linear motor 79 based on the signal from the tracking control circuit 73. The optical head 5 is fixed to the linear motor 79, and the optical head 5 is moved in the tracking direction.

The scale sensor 81 is connected to the linear motor control circuit 77. The scale sensor 81 detects the position of the optical head 5 in the tracking direction.

Next, the inside of the focusing control circuit 45 and the tracking control circuit 73 in the above optical recording / reproducing apparatus will be described.

The focusing control circuit 45 and the tracking control circuit 73 have the function of generating the servo error signals of the focus system and the tracking system as described above, and in the present invention, the bandwidth of the signal processing circuit is widened. The purpose is to improve.

The signal processing circuit of the present invention is shown in FIG.

The output current Iin from the photodetector PD corresponding to each of the position sensors 29 and 31 is input to the current mirror circuit CM including the transistors Q1, Q2 and Q3 and the resistors R1, R2 and R3, and the first and second currents are inputted. Output current amplified signals Iout1 and Iout2 (Iin
= I _OUT1 = I _OUT2 ).

Such a current mirror circuit CM is shown in FIG.
As shown in Fig. 4, four are used and the output end OU of the first current amplification signal
T1 is used for servo error signal detection, and the output terminal OUT2 of the second current amplified signal is used as the sum signal for automatic gain control (AGC).

Focusing and tracking system servo error signals IN1 and IN2 are generated from each output terminal OUT1 and input to the automatic gain control circuit AGC.

FIG. 4 shows the internal structure of the above automatic gain control circuit AGC. Automatic gain control is performed using the function of a four-quadrant multiplier composed of transistors Q11 to Q18.
The output signal amount is controlled to be constant so as to cancel the influence of the light amount variation of the servo signal.

As the signal for controlling the gain, the sum current of the output OUT2 of the current mirror circuit CM is converted into a current / voltage by the differential operation unit OP6, and is used as a voltage.

However, the system of the servo error signal is input to the input terminals IN1 and IN2 of FIG.
2 is output.

By taking the difference between the output currents IC1 and IC2 with the differential circuit OP, the output signal of the automatic gain control circuit AGC is output as a current signal.

Finally, the output of the automatic gain control circuit AGC is
Current / voltage conversion is performed by the differential operational amplifier OP5 in FIG.

Therefore, the output current of the servo position sensor is
As processing of the servo error signal, signal processing from the current mirror circuit CM to the automatic gain control circuit AGC is performed by a current signal as shown in FIG. 3A, and finally, a voltage signal is obtained by the voltage-current converter OP. .

That is, according to the present invention as described above, it is possible to mitigate the problems of the deterioration of the band characteristic and the deterioration of the phase rotation characteristic, which are caused by the conventional voltage signal processing only.

As described above, the optical recording / reproducing apparatus of the present invention realizes a wide band of the focus / track control circuit which receives the detection current from the focus / track position sensor, thereby realizing a wide servo band. Even during high speed and high-speed seek operations, the tracking error detection ability is improved, and higher-speed and highly accurate seek operations are possible.

Further, since the problem concerning the supply voltage to the device is reduced, the supply voltage can be lowered.

[0057]

Therefore, as described in detail above, according to the present invention, by using the current amplifying means such as the current mirror circuit by the current processing method capable of improving the frequency characteristic and the phase rotation characteristic, the tracking and focusing servo can be performed. It is possible to provide an optical recording / reproducing device that can realize a wide band of a system circuit.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing a device configuration of the present invention.

FIG. 2 is a block diagram showing a main part of the present invention.

FIG. 3 is a block diagram showing a main part of the present invention.

FIG. 4 is a block diagram showing a main part of the present invention.

FIG. 5 is a block diagram of a main part showing a conventional technique.

FIG. 6 is a block diagram of a main part showing a conventional technique.

FIG. 7 is a block diagram of a main part showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical disk, 5 ... Optical head, 19 ... Focus coil, 29 ... Focus position sensor, 45 ... Focusing control circuit, 61 ... Control circuit, 31 ... Track position sensor, 73 ... Tracking control circuit, 21 ... Track coil, CM ... Current mirror circuit, AGC ... Automatic gain control circuit, OP5, OP6 ... Differential calculator.

Claims (5)

[Claims] 1. An optical recording / reproducing apparatus for irradiating a light beam onto an optical recording medium to optically record / reproduce information, wherein a reflected light from the optical recording medium is received to generate a current signal for focusing and tracking. A sensor unit for outputting, a current amplifying unit for amplifying a current signal from the sensor unit, a focusing and tracking servo signal based on the current amplified signal from the current amplifying unit, and a servo signal based on the servo signal. An optical recording / reproducing apparatus comprising: a servo unit that controls focusing and tracking of the light beam with respect to the optical recording medium. 2. An optical recording / reproducing apparatus for irradiating a light beam onto an optical recording medium to optically record / reproduce information, wherein the reflected light from the optical recording medium is received to generate a current signal for focusing and tracking. Output 1st to 4th
And first to fourth current mirror circuits for amplifying current signals from the first to fourth photodiodes and outputting first and second current amplified signals, respectively. A servo signal for focusing and tracking based on each of the first current amplified signals from the first to fourth current mirror circuits, and a signal for automatic gain control based on each of the second current amplified signals. An optical gain control circuit for controlling; and a means for performing current-voltage conversion of a servo signal from the automatic gain control circuit to perform focusing and tracking control of the light beam with respect to the optical recording medium. Recording / playback device. 3. An optical recording / reproducing apparatus for irradiating a light beam onto an optical recording medium to optically record and reproduce information, wherein a reflected light from the optical recording medium is received to generate a current signal for focusing and tracking. Output 1st to 4th
And a first to a third photodiode for amplifying the current signals from the first to fourth photodiodes and outputting the first and second current amplified signals, respectively. First to fourth current mirror circuits composed of transistors and first to third resistors, and focusing based on each first current amplification signal from the first to fourth current mirror circuits. An automatic gain control circuit for controlling a tracking servo signal by a signal for automatic gain control based on each second current amplification signal; and a light beam obtained by current-voltage converting the servo signal from the automatic gain control circuit. And a means for performing focusing and tracking control on the optical recording medium. 4. An optical recording / reproducing apparatus for irradiating a light beam onto an optical recording medium to optically record / reproduce information, wherein the reflected light from the optical recording medium is received to generate a current signal for focusing and tracking. Output 1st to 4th
And first to fourth current mirror circuits for amplifying current signals from the first to fourth photodiodes and outputting first and second current amplified signals, respectively. And a signal for automatic gain control based on each second current amplified signal, which is a servo signal for focusing and tracking based on each first current amplified signal from the first to fourth current mirror circuits. For controlling, an automatic gain control circuit having a four-quadrant multiplier function and composed of first to eighth transistors, and a current-voltage conversion of a servo signal from the automatic gain control circuit are performed. And a means for performing focusing and tracking control on the optical recording medium. 5. An optical recording / reproducing apparatus for irradiating a light beam on an optical recording medium to optically record / reproduce information, wherein the reflected light from the optical recording medium is received to generate a current signal for focusing and tracking. Output 1st to 4th
And a first to a third photodiode for amplifying the current signals from the first to fourth photodiodes and outputting the first and second current amplified signals, respectively. First to fourth current mirror circuits composed of transistors and first to third resistors, and focusing based on each first current amplification signal from the first to fourth current mirror circuits. In order to control the tracking servo signal by a signal for automatic gain control based on each second current amplification signal, an automatic gain having a four-quadrant multiplier function and composed of first to eighth transistors A control circuit, and means for performing current-voltage conversion of the servo signal from the automatic gain control circuit to perform focusing and tracking control of the light beam with respect to the optical recording medium. Optical recording and reproducing apparatus according to.