JP2629104B2 - Focus / track servo controller for optical disk drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus servo system for controlling a focus of irradiation light of an optical head of an optical disk apparatus, and a track for controlling the irradiation light from the optical head to follow a track on the optical disk. The present invention relates to a focus / track servo control device of an optical disk device that controls a servo system.

[0002]

2. Description of the Related Art FIG. 11 is an explanatory view of a conventional optical disk device. FIG. 11A is a schematic configuration diagram of a part of the optical disk device, and FIG. 11B is a configuration diagram of a focus / track servo control unit.

In the figure, 1 is an optical disk, 2 is an optical head,
3 is a track servo controller, 4 is a focus servo controller, 5 is a spindle motor, 6 is a track actuator, 7 is an objective lens, 8 is a focus actuator,
9 is an optical unit, 10 is a four-divided light receiver, 11 is a light receiver, 1
2 is a light source (semiconductor laser), 14 and 17 are differential amplifiers,
15 and 18 are amplifiers, 16 and 19 are power amplifiers, VR
1, VR2 indicates a variable resistor, and R1 to R11 and r1 to r4 indicate resistors.

Conventionally, in an optical disk apparatus, as shown in FIG. 11A, an optical head 2 is moved in a radial direction of an optical disk 1 to be positioned with respect to an optical disk 1 rotated about a rotation axis by a spindle motor 5. The optical head 2 reads (reproduces) / writes (records) the optical disk 1.

On the other hand, the optical head 2 guides the light emitted from the light source (semiconductor laser) 12 to the objective lens 7 via the optical section 9, narrows down the spot light by the objective lens 7, and irradiates the spot light.

Then, the reflected light from the optical disk 1 is guided to the optical unit 9 via the objective lens 7, the branched light from the optical unit 9 is received by the light receiver 11, and further divided into four light receivers 10.
It is configured to be incident on.

In such an optical disk device, a large number of tracks or pits are formed at intervals of several microns in the radial direction of the optical disk 1, and the positional deviation of the track is large even by a slight eccentricity. The beam spot deviates in focus position, and it is necessary to follow the beam spot of 1 micron or less.

For this purpose, a focus actuator (focus coil) 8 for moving the objective lens 7 of the optical head 2 in the vertical direction in the figure to change the focus position, and moving the objective lens 7 in the horizontal direction in the figure to change the irradiation position Track actuator (track coil) 6 for changing the direction of the track in the track direction
And a focus servo controller 4 for driving a focus actuator 8 from a light receiving signal of the light receiver 10 and a track error signal TES from a light receiving signal of the light receiver 10. A track servo controller 3 for driving the motor 6 is provided.

In the above-mentioned optical disk apparatus, stable track servo control can be performed by adjusting the gain of the track servo, even when an optical disk having various groove shapes or an optical disk with a groove shape with high precision is used. Such a technique has been known (for example, JP-A-63-224034).

However, in the above-mentioned conventional example, only the gain fluctuation caused by the groove shape of the optical disk (medium) can be adjusted. Therefore, the servo gain fluctuates according to other fluctuation factors, for example, the performance of the actuator, the assembling accuracy of the optical system, and the like, but cannot be adjusted for these.

Although the optical disk device also requires a focus servo, the above-mentioned conventional example does not show the adjustment of the focus servo gain. Therefore, conventionally, for example, the focus servo control unit 4 and the track servo control unit 3 are configured as shown in FIG.

In FIG. 11B, outputs a, b, c, and d of the four-divided light receiver 10 are input to the focus servo control unit 4 and the track servo control unit 3. The focus servo control unit 4 is provided with a differential amplifier 14 for receiving the output signal of the four-divided light receiver 10, an amplifier 15 whose gain can be adjusted by the variable resistor VR1, and a power amplifier 16, and the track servo control unit 3 Is provided with a differential amplifier 17 for receiving an output signal of the four-divided light receiver 10, an amplifier 18 whose gain can be adjusted by a variable resistor VR2, and a power amplifier 19.

Then, the total gain (loop transfer function)
Has been adjusted by the variable resistors VR1 and VR2 so as to have a predetermined value, and focus servo control and track servo control have been performed.

[0014]

The above-mentioned conventional apparatus has the following problems. (1) In the conventional example shown in FIG. 11B, the servo gain is adjusted by a variable resistor. However, since the variable resistor has a sliding portion, it is easily affected by environmental changes and changes over time.

Therefore, even if the adjustment is performed once, the servo gain changes due to a subsequent environmental change or a change over time, so that stable focus servo control and track servo control cannot be performed.

(2) In the conventional example shown in FIG. 11B, when the optical system is replaced, the circuit parts such as the focus servo control unit and the track servo control unit are replaced, or the servo is controlled by a variable resistor. It is necessary to readjust the gain.

Therefore, it is troublesome and costly. An object of the present invention is to solve such a conventional problem and to enable focus servo control and track servo control that are stable against environmental changes and changes over time.

[0018]

FIG. 1 is a principle diagram of the present invention, wherein A is a principle diagram (1) and B is a principle diagram (2). In the figure, the same reference numerals as those in FIG. Reference numeral 20 denotes a control unit, 21 denotes a servo gain determination unit, 22A denotes a nonvolatile memory, and 23 denotes a servo control unit.

The present invention has the following configuration in order to solve the above problems.

(1): an optical head 2 that irradiates a spot light to the optical disc 1 and receives light from the optical disc 1 to obtain a light receiving signal;
The focus error signal (FES), and
Illumination of the optical head 2 based on the cas error signal (FES)
Focus servo control to control the focus position of the spot light
A track error signal (TES) is obtained from the control unit 4 and the light receiving signal of the optical head 2, and the track error signal (TES) is obtained.
(TES) , the focus / track of an optical disc apparatus having a servo control system including a track servo control unit 3 for controlling the position of an irradiation spot light of the optical head 2.
In the servo control device , a nonvolatile memory 22A for setting a predetermined gain (FSG, TSG) is provided in the servo control system.
The control unit 4 is provided with a variable gain amplifier,
The gain setting value (FSG) is read from the memory 22A,
The gain setting value is set in the variable gain amplifier,
In addition to performing focus servo control, the track servo control unit 3 is provided with a variable gain amplifier, reads a gain setting value (TSG) from the nonvolatile memory 22A, and sets the gain setting value in the variable gain amplifier. Thus, track servo control is performed. "

(2): An optical head 2 that irradiates an optical disk 1 with spot light, receives light from the optical disk 1 and obtains a light receiving signal, and a track error signal (TES) from a light receiving signal of the optical head 2 In the track servo control device for an optical disc provided with a servo control system including a track servo control unit 3 for controlling the position of the irradiation spot light of the optical head 2 based on the track error signal (TES), A predetermined value of gain (T
Provided with a non-volatile memory 22A to set the SG), a variable gain amplifier provided in the track servo controller 3, from the nonvolatile memory 22A, the gain setting value
(TSG) is read out, the target amplitude calculated by the gain setting value and the track error signal (TE
The track servo control is performed by setting a gain in the variable gain amplifier so that S) becomes equal to the variable gain amplifier. "

[0022]

The operation of the present invention based on the above configuration will be described with reference to FIG. Operation: Refer to the principle diagram (1) in FIG. 1A. A focus servo control unit 4 is provided in the servo control unit 23, and a variable gain amplifier is provided in the focus servo control unit 4.

At the time of adjustment in a factory or the like, a gain setting value (focus servo gain) at which the servo is in an optimum state is obtained, and the value is set in the nonvolatile memory 22A.

At the time of normal operation, for example, at the time of apparatus startup processing after power-on, the servo gain determination section 21 in the control section 20 reads the gain setting value (FS) from the nonvolatile memory 22A.
G) is read out, and the servo gain (FSG) is set in the variable gain amplifier provided in the focus servo control unit 4 in the servo control unit 23.

Thereafter, the set servo gain (FSG)
Is used to perform focus servo control. Operation: Refer to the principle diagram (1) in FIG. 1A. A track servo control unit 3 is provided in the servo control unit 23, and a variable gain amplifier is provided in the track servo control unit 3.

The non-volatile memory 22A has T
SG (track servo gain) is set in the same manner as the operation. During normal operation, the servo gain determination unit 21 in the control unit 20 reads a gain set value from the nonvolatile memory 22A and sets a servo gain (TSG) in the variable gain amplifier.

Thereafter, the set servo gain (TSG)
Is used to perform track servo control. Operation: Refer to the principle diagram (2) in FIG. 1B. A track servo control unit 3 is provided in the servo control unit 23, a variable gain amplifier is provided in the track servo control unit 3, and the track servo control unit 3 is provided. , The amplitude value of the track error signal TES is taken out from the control unit 20.

A predetermined servo gain (TSG) is set in the nonvolatile memory 22A. During normal operation, the servo gain determination unit 21 in the control unit 20 reads a gain setting value (TSG) from the non-volatile memory 22A, and calculates a target amplitude calculated based on the gain setting value and a track error. The servo gain (TSG) is set in the variable gain amplifier so that the amplitude of the signal TES becomes equal, and track servo control is performed.

In this way, stable focus servo control or track servo control can be realized against environmental changes or changes over time without using a variable resistor as in the prior art.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. (Explanation of First Embodiment) FIGS. 2 to 8 are diagrams showing a first embodiment of the present invention, and FIG.
3 is a configuration diagram of an optical head and a servo control unit, a configuration example of a servo control unit and a control unit of FIG. 4, FIG. 5 is a configuration example of a variable gain amplifier, FIG. 6 is an explanatory diagram of focus / track servo control, and FIG. Is a processing flowchart at the time of adjustment in a factory, and FIG. 8 is a processing flowchart at the time of normal operation.

In the drawings, the same reference numerals as those in FIGS. 1 and 11 denote the same components. Reference numeral 24 denotes a light amount control unit, 25 denotes a spindle motor control unit, 26 denotes a read / write circuit, 27 denotes a controller, 28 denotes a host, 29 denotes a magnetic field generation unit, 30 denotes a beam splitter, 31 denotes a quarter-wave plate, 32 Is a half mirror, 33 is a critical angle prism, 34 is a mirror, 35 is a lens, 36 is a moving mechanism, 37 is a lens, 38 is an MPU (microprocessor), 39 is a track, 15A and 18A.
Indicates a variable gain amplifier.

Further, R1 to R8, r1 to r4, R01,
R21, R41 and R81 are resistors, S1 to S8 are analog switches, and Rf is a feedback resistor. (1) Description of the optical disk device used in the first embodiment ...
2 to 5 show the configuration of the optical disk device in this embodiment is shown in FIG.
The optical disk device includes a controller 27, a control unit 2
0, read / write (R / W) circuit 26, servo controller 23, optical head 2, light amount controller 24, spindle motor controller 25, spindle motor 5, optical disk (recording medium) 1, magnetic field generator 29, E ² PROM 22 and the like are provided.

The optical disk device is connected to the host 2
8 for use. The optical head 2 and the servo control unit 23 are configured as shown in FIG. 3, for example.

As shown in the drawing, the optical head 2 is positioned at a desired track position in the radial direction of the disk 1 by the moving mechanism 36 having the optical head 2 mounted on the optical disk 1 rotated by the spindle motor 5. Have been.

The optical head 2 transmits light emitted from the semiconductor laser 12 as a light source to a lens 35, a beam splitter 30,
The recording / reproducing is performed by irradiating the optical disc 1 with the aperture stopped down through the １ ／ λ wavelength plate 31, the mirror 34 and the objective lens 7, and the reflected light from the optical disc 1 is reflected by the objective lens 7, the mirror 34 and the λλ wavelength plate. 31, light is received via the beam splitter 30, guided to the lens 37 and the light receiver 11 via the half mirror 32, and a reproduction signal RFS is obtained. Further, a track error is received from the light receiver 10 via the half mirror 32 and further via the critical angle prism 33. Signal TE
S, is configured to obtain a focus error signal FES.

In the optical disk device, the optical disk 1
A large number of tracks or pits are formed at intervals of several microns in the radial direction of the optical disk 1, and even if the eccentricity is slight, the track position shift is large. It is necessary to make the following irradiation light follow.

Therefore, a focus actuator 8 for moving the objective lens 7 of the optical head 2 in the vertical direction in the figure to change the focal position, and moving the objective lens 7 in the horizontal direction in the figure to shift the irradiation position in the track direction. A track actuator 6 to be changed is provided, a focus error signal FES is generated from a light receiving signal of the light receiver 10, and a focus servo controller 4 for driving the focus actuator 8, and a track error signal TES is generated from the light receiving signal of the light receiver 10. A track servo control unit 3 that generates a signal and drives a track actuator 6 is provided.

FIG. 4 shows a configuration example of the servo control unit 23 and the control unit 20. As shown in the figure, the focus servo control unit 4 basically includes a differential amplifier 14 for generating a focus error signal FES, a variable gain amplifier 15A for amplifying an output signal of the differential amplifier 14, and a variable gain amplifier The power amplifier 16 amplifies the output signal of the 15A and drives the focus actuator 8 (see FIG. 3).

The -a terminal and the b output of the photodetector 10 are connected to the minus terminal of the differential amplifier 14 via the input resistors R3 and R4, respectively.
The side terminals are connected to the c of the light receiver 10 via the input resistors R1 and R2.
The differential amplifier 14 outputs (−FES) of {(c + d) − (a + b)}. Note that r1 is a bias resistor, and r2 is a feedback resistor.

The track servo controller 3 includes a differential amplifier 17 for generating a track error signal TES and a variable gain amplifier 18A for amplifying an output signal of the differential amplifier 14.
And a power amplifier 19 that amplifies the output signal of the variable gain amplifier 18A and drives the track actuator 6 (see FIG. 3).

The negative terminal of the differential amplifier 17 has an input resistor R
The outputs a and d of the optical receiver 10 are given via R5 and R6, and the outputs b and c of the optical receiver 10 are given to the + terminal via input resistors R7 and R8.
(-TES) of {(b + c)-(a + d)} is output. Note that r3 is a bias resistor, and r4 is a feedback resistor.

The control unit 20 is provided with an MPU (microprocessor) 38, and the control unit 20 is connected to an E ² PROM 22 which is a nonvolatile memory. This E ² P
As will be described later, predetermined data (FSG, TSG) is stored in the ROM 22 at the time of adjustment in the factory, and is read and used by the MPU 38 during operation.

The output of the MPU 38 includes a terminal T ₁ of the focus servo control unit 4, be tied to terminal T ₂ of the track servo controller 3, the variable gain amplifier 15A from MPU 38, so that it can set the servo gain to 18A Keep it.

FIG. 5 shows a configuration example of the variable gain amplifier 15A of the focus servo control unit 4 and the variable gain amplifier 18A of the track servo control unit 3 shown in FIG. These variable gain amplifiers 15A and 18A are connected to operational amplifiers OP1 and OP1,
Feedback resistor Rf, analog switches S1 to S8, resistor R0
1, R21, R41 and R81.

The analog switches S1 to S8
Is turned on / off by a signal from the MPU 38 (see FIG. 4).
Controlled off. If all of the analog switches S1 to S8 are off, only the resistor R01 is connected to the negative input terminal of the operational amplifier, but if any of the analog switches is on, the resistor R01 is connected in series with the turned on analog switch. A resistor is connected in parallel with the resistor R01.

Therefore, the analog switches S1 to S8 are set to M
If on / off control is performed with a signal from the PU 38, the input resistance of the operational amplifier OP1 changes, and the gain of the variable gain amplifier can be changed.

(2) Description of Operation of Optical Disk Apparatus--FIG.
First, basic operations of focus servo control and track servo control will be described with reference to FIG.

When performing the focus servo control, a, b,
In the case of using the quadrant light receiving device 10 of c and d, FIG.
As shown in (A), when the focus of the irradiation light coincides with the recording surface of the optical disc 1 is f, and when the focus is out of focus before and after that is f ₁ and f ₂ , the light passes through the critical angle prism 33. The distribution of the amount of reflected light in the light receiver 10 is shown in FIGS.
(D).

That is, when the focal point is f ₁ , FIG.
When the focus is f (focus), FIG. 6C is obtained, and when the focus is f ₂ , FIG.
Then, when the output {(a + b)-(c + d)} of the light receiver 10 is obtained, the focus error signal FES shown in FIG. 6 (E) is obtained. This method is known as a critical angle method using a critical angle prism 33, as is well known.

Therefore, if the focus actuator 8 is driven by the focus error signal FES and the objective lens 7 is driven up and down, the focus of the irradiation light on the recording surface of the optical disc 1 in the submicron order regardless of the undulation of the optical disc 1. Can be followed.

When the track servo control is performed, as shown in FIG. 6F, the distribution of the amount of reflected light in the light receiver 10 depends on the position of the irradiation light with respect to the track 39 and the interference of light by the track causes the distribution of the amount of light reflected in FIG. ) To (I).

That is, the distribution of the amount of reflected light in the light receiver is shown in FIG. 6 (G) when the irradiation light has a positional relationship like P ₁ with respect to the track 39, and when the irradiation light is at P with respect to the track 39 (ON). If the track), as shown in FIG. 6 (H), the irradiation light 6 becomes (I) is when in P ₂ relative to the track 39.

Therefore, when the output {(a + d)-(b + c)} of the photodetector 10 is obtained by the track servo controller 3, the track error signal TES shown in FIG. 6 (J) is obtained. And the objective lens 7 is driven in the left-right direction, the irradiation light can be controlled to follow the track 39 of the optical disc 1 regardless of the eccentricity of the optical disc 1.

Description of Processing at the Time of Adjustment in the Factory When adjusting the optical disk apparatus in the factory (at the time of assembling a product, etc.), the value of the loop transfer function (total servo gain) of the focus servo and the track servo is measured. seeking a predetermined value FSG (focus servo gain) and TSG (track servo gain), the process of writing in a partial region of the E ² PROM 22 (see FIG. 4).

The processing at this time will be described with reference to FIG. Each processing number in FIG. 7 is shown in parentheses. In this process, the power is turned on (S1), power is supplied to the optical disk device, and the spindle motor 5 is rotated (S1).
2) The semiconductor laser (laser diode L) of the light source 12
D) is turned on (S3).

Thereafter, the focus is pulled in under the control of the focus servo controller 4 (S4). Next, a command is issued from the outside to the MPU 38 of FIG. 4 to increase the FSG by +1 or -1 (add or subtract FSG) so that the loop transfer function of the focus servo becomes a predetermined value. Upon receiving this instruction, the MPU 38 sets FSG to +1 or -1.
Then, the gain of the variable gain amplifier 15A is changed.

In this case, the FSG is changed as described above (S5), and the value of the loop transfer function is measured using a measuring instrument such as a signal analyzer (S6) until the value becomes a predetermined value (S6). S7) Repeat.

When the FSG (focus servo gain) which becomes a predetermined loop transfer function is obtained, the MPU 38
, An instruction to write the FSG into the E ² PROM 22 is issued.

[0059] MPU38 having received the instruction writes a value of FSG into E ² PROM22 (S8). Next, the MPU 3 controls the track servo control unit 3 so that the loop transfer function of the track servo at the time of control by the track servo control unit 3 becomes a predetermined value.
For 8, a command to increase TSG (track servo gain) by +1 or −1 (add or subtract TSG) is issued.

Upon receiving this instruction, the MPU 38
+1 or −1 to change the gain of the variable gain amplifier 18A. Also in this case, the TSG is changed (S
9) While measuring the value of the loop transfer function with the measuring device (S10), the process is repeated until the value of the loop transfer function reaches a predetermined value (S11).

When a TSG that becomes a predetermined loop transfer function is obtained, the TSG is externally transmitted to the MPU 38 by E ² PRO.
Issue a command to write to M22. MPU that received this command
At 38, the TSG data input from the outside is converted to E ² PR
Write to OM22 (S12).

Description of Processing During Normal Operation (Normal Operation) In normal operation (after shipment from the factory, when used by a user), for example, when power is supplied to the optical disk apparatus to perform startup processing of the apparatus, The MPU 38 reads the data from the E ² PROM 22 and sets gains in the variable gain amplifiers 15A and 18A of the focus servo control unit 4 and the track servo control unit 3.

Hereinafter, the above processing will be described with reference to the processing flowchart of FIG. Each processing number in FIG. 8 is shown in parentheses. First, the power is turned on to supply power to the optical disk device (S21). Thereafter, the MPU 38 in the control unit 20 reads the FSG from the E ² PROM 22 (S22), and sets the FSG in the variable gain amplifier 15A of the focus servo control unit 4 (S23).

The MPU 38 reads the TSG from the E ² PROM 22 (S24), and sets the TSG in the variable gain amplifier 18A of the track servo controller 3 (S24).
25).

Then, the spindle motor 5 is rotated (S26), and the semiconductor laser (laser diode) of the light source 12 is turned on (S27). Next, the pull-in control of the focus servo is performed (S28), and the pull-in control of the track servo is further performed (S29, and a ready state is set).

Thereafter, normal data reading or data writing is performed while performing focus servo control and track servo control. (Explanation of the Second Embodiment) FIGS. 9 and 10 show a second embodiment of the present invention. In FIG. 9 and FIG. Reference numeral 40 denotes an A / D (analog / digital) converter, and reference numeral 41 denotes an amplitude detector.

(1) Description of servo control unit and control unit ...
Refer to FIG. 9. Servo control unit 23 and control unit 20 in the second embodiment.
FIG. 9 shows the configuration (see FIG. 2).

In this example, the structures of the focus servo control unit 4 and the track servo control unit 3 provided in the servo control unit 23 are the same as those of the first embodiment shown in FIG.
The configuration of the control unit 20 is different from that of the first embodiment.

That is, the control unit 20 is provided with an A / D converter (analog / digital converter) 40 and an amplitude detection unit 41 in addition to the MPU (microprocessor) 38.

The amplitude detector 41 is connected to a point A on the output side of the variable gain amplifier 18A in the track servo controller 3. Then, the amplitude (voltage value) of the track error signal TES on the output side of the variable gain amplifier 18A is detected. The detected amplitude value is converted into a digital signal by the A / D converter 40 and input to the MPU 38.

The MPU 38 calculates the amplitude data and E ²
The gain (TSG) is set in the variable gain amplifier 18A using the gain setting value read from the PROM 22. Description of the process at the time of normal operation in the second embodiment ... See FIGS. 9 and 10. In the second embodiment, the process up to writing the FSG and TSG in the E ² PROM 22 is the same as in the first embodiment. Do.

A normal operation is performed in a state where the FSG and the TSG are written in the E ² PROM 22. Hereinafter, the processing at the time of the normal operation in the second embodiment will be described based on the processing flowchart of FIG. Each processing number in FIG. 10 is shown in parentheses.

First, the power is turned on to supply power to the optical disk device (S31). Thereafter, the MPU 38 in the control unit 20 reads out the FSG from the E ² PROM 22 (S32), determines the gain, and sets the gain in the variable gain amplifier 15A of the focus servo control unit 4 (S3).
3).

Next, the spindle motor 5 is rotated (S
34), the light source (laser diode LD) 12 is turned on (S35), and under the control of the focus servo controller 4,
Focus servo pull-in is performed (S36).

Thereafter, the MPU 38 in the control unit 20
The TSG is read from the E ² PROM 22 (S37). Here, the MPU 38 multiplies the deviation from the standard value of the TSG by the standard value of the track error signal, and uses the result as a target value (S38).

The MPU 38 changes the gain setting of the variable gain amplifier 18A of the track servo controller 3 (S39) so that the signal amplitude at the output side of the variable gain amplifier 18A, that is, at the point A becomes equal to the target value. (S40).

For example, the standard value of TSG is 1, and the standard amplitude value of the track error signal TES (the output signal of the differential amplifier 17) is 500 mV. In this case, the E ² PROM 22
Assuming that the TSG read out from is 1.3, the target value = 500 × 1.3 = 650 (mV).

Therefore, the signal amplitude value at point A is 650 (m
V), the variable gain amplifier 18A is set. Thereafter, the track servo pull-in control is performed (S4
1) The device enters a ready state.

For the “standard value of TSG” and “standard amplitude value of track error signal”, values obtained at the time of designing the device are set in a program used by the control unit 20 and these values are set. The above processing is performed using the above.

The “deviation from the standard value of TSG” is
It is obtained by calculation from the value read from the E ² PROM and the above “standard value of TSG”. In the above specific example (numerical example), since the standard value of TSG is 1, this value is equal to “the deviation from the standard value of TSG”.

(Other Embodiments) Although the embodiments have been described above, the present invention can be implemented as follows. (1) The controller 27 in FIG. 2 may have a different configuration (independent controller) from the optical disk device, and may be provided between the host 28 and the optical disk device.

(2) The E ² PROM 22 may use another nonvolatile memory. (3) The present invention is also applicable to an optical disk device having a configuration different from that of the above embodiment.

[0083]

As described above, the present invention has the following effects. (1) It is not necessary to use a sliding component such as a variable resistor as a circuit component of the focus servo control unit or the track servo control unit.

Therefore, with respect to environmental changes and changes over time,
Stable focus servo control and track servo control can be performed. (2) When the optical system is replaced, setting the gain setting value specific to the optical system in the non-volatile memory always enables focus servo control and track servo control with a predetermined loop transfer function. It can be carried out.

Therefore, stable focus / track servo control can be realized. (3) At the time of adjustment in a factory, it is necessary to measure FSG and TSG and write them to a non-volatile memory (such as an E ² PROM).

However, in this case, there is no need to use a special measuring instrument, and a simple operation is sufficient.

[Brief description of the drawings]

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

FIG. 2 is a configuration example of an optical disc device according to a first embodiment of the present invention.

FIG. 3 is a configuration diagram of an optical head and a servo control unit in the first embodiment.

FIG. 4 is a configuration example of a servo control unit and a control unit in the first embodiment.

FIG. 5 is a configuration example of a variable gain amplifier according to the first embodiment.

FIG. 6 is an explanatory diagram of focus / track servo control in the first embodiment.

FIG. 7 is a processing flowchart at the time of adjustment in a factory according to the first embodiment.

FIG. 8 is a processing flowchart during a normal operation in the first embodiment.

FIG. 9 is a configuration example of a servo control unit and a control unit in a second embodiment.

FIG. 10 is a processing flowchart during a normal operation in the second embodiment.

FIG. 11 is an explanatory diagram of a conventional optical disk device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical disk (recording medium) 2 Optical head 20 Control part 21 Servo gain determination part 22A Non-volatile memory 23 Servo control part

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Isao Masaki, Inventor Fujitsu Limited, 1015 Uedanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture (56) References JP-A-3-30123 (JP, A) JP-A-4-206037 (JP, A)

Claims (2)

(57) [Claims] An optical head (2) for irradiating an optical disk (1) with spot light and receiving light from the optical disk (1) to obtain a light receiving signal; and a light receiving signal of the optical head (2). To obtain a focus error signal (FES) from the focus error signal (FES).
A focus servo control unit (4) for controlling the focal position of the irradiation spot light of the optical head (2) based on ES) and a track error based on a light receiving signal of the optical head (2).
Signal (TES), the track error signal (TE)
S), the position of the irradiation spot light of the optical head (2)
Focus / track of an optical disc apparatus provided with a servo control system including a track servo control unit (3) for controlling the positioning.
In click servo controller, the servo control system, a predetermined gain (FSG, TSG)
Is provided, and the focus servo control unit (4) is provided with a variable gain amplifier (15A), and the nonvolatile memory (22A)
, A gain setting value (FSG) is read out, and the gain setting value is set in the variable gain amplifier (15A).
In addition to performing focus servo control , the track servo control unit (3) includes a variable gain amplifier.
A nonvolatile memory (22A).
The gain setting value (TSG) is read from the
Is set in the variable gain amplifier (18A),
A focus / track servo control device for an optical disk device characterized by performing a servo control. " 2. An optical disk (1) is irradiated with a spot light.
And receives the light from the optical disk (1), and
An optical head (2) to obtain and a track error signal from a light receiving signal of the optical head (2).
Signal (TES) and the track error signal (TES)
Based on the position of the irradiation spot light of the optical head (2)
Servo control including track servo control unit (3) to control
Track servo control device for optical discs with
And sets a predetermined value gain (TSG) in the servo control system.
A non-volatile memory (22A) to be provided and a variable gain amplifier in the track servo control unit (3).
(18A), the nonvolatile memory (22A)
The gain setting value (TSG) is read from the
The target amplitude calculated based on the value and the track
In order to make the error signal (TES) equal, the variable
Set the gain to the gain amplifier (18A) and
Optical disk drive characterized by performing servo control
Rack servo controller. "