JP3208859B2 - Recording and / or reproducing apparatus for disc-shaped recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a read-only optical recording medium (generally called a CD-ROM), a rewritable optical recording medium, and a magneto-optical medium rewritable by light modulation or magnetic field modulation. The present invention relates to a recording and / or reproducing apparatus for performing recording and / or reproduction on a disk-shaped recording medium such as a recording medium.

[0002]

2. Description of the Related Art Recently, as a disk-shaped recording medium, a read-only optical recording medium (generally called a CD-ROM), a rewritable optical recording medium, and other rewritable optical modulation or magnetic field modulation are possible. Various magneto-optical recording media have been proposed, and at present, CD-ROMs and magneto-optical recording media have been put to practical use.

Here, a magneto-optical recording medium (hereinafter referred to as a magneto-optical disk) will be referred to as one example. And
A recording and / or reproducing apparatus (hereinafter simply referred to as a recording / reproducing apparatus) for writing and reading an information signal to / from the magneto-optical disk includes a light beam for recording and / or reproducing the information signal to / from the magneto-optical disk. And an optical head provided with an objective lens for focusing the light beam on a recording layer (perpendicular magnetization film) of the magneto-optical disk.

This optical head is provided with a focus adjustment mechanism for focusing a light beam on a magneto-optical disk and a tracking adjustment mechanism for irradiating a light beam along a recording track of the magneto-optical disk.

In an actual magneto-optical disk, a rotation of several tens of microns causes a surface deflection and a core deflection with rotation, and the size of a magnetic domain recorded by a light beam is 1 μm.
Since it is as small as about m, it is very difficult to focus the light beam on the magneto-optical disk on which the above-mentioned surface runout and center runout occur.

Therefore, various focus adjusting mechanisms have been conventionally proposed, and as a method of detecting a focusing error signal which is a basis of the adjusting operation of the mechanism, an astigmatism method, a knife edge method, a Foucault method and the like are presently used. is there.

In the astigmatism method, as shown in FIG. 6, a cylindrical lens 102 is inserted between an objective lens 101 and a focus error detection plane P, and as shown in FIG. When 103 is at the focal position of the objective lens 101, the reflected light from the magneto-optical disk 103 is
It is configured to focus on the z point. The focus error detection surface P is arranged at a position where the area of the reflected light is the smallest. The z point does not change in the direction perpendicular to the paper surface due to the properties of the cylindrical lens 102, but focuses on the x point in the direction parallel to the paper surface.

Therefore, as described above, the magneto-optical disk 1
When 03 is at the focal position of the objective lens 101, the beam cross section of the reflected light on the focus error detection plane P is substantially a perfect circle. When the four-division photodiodes (a, b, c, d) are placed on the focus error detection surface P, the spot S on the four-division photodiodes (a, b, c, d) becomes almost a perfect circle, a, b, c and d
The output (energy) of the light beam impinging on is the same. Therefore, as shown in FIG. 7, two photodiodes (a, b) and (c, d) having a diagonal positional relationship are connected to corresponding adders 104 and 105, respectively. In the above case, the output from the differential amplifier 106 becomes zero by adopting a circuit configuration in which a difference from the output from the differential amplifier 105 is obtained by the differential amplifier 106 at the subsequent stage.

However, as shown in FIG. 6A, when the magneto-optical disk 103 is too close to the objective lens 101, the focal point behind the cylindrical lens 102 moves to the points z _K and x _K , and the reflection on the focus error detection plane P The beam cross section of the light is
The direction perpendicular to the plane of the paper is thick and the direction parallel to the plane of the paper is narrow, and the spot S on the four-division photodiode (a, b, c, d) becomes a vertically long ellipse in the drawing. In this case, the output level from one adder 104 is
5, the output level of the differential amplifier 10
6 outputs a signal of a positive level.

On the other hand, as shown in FIG. 6C, when the magneto-optical disc 103 is too far from the objective lens 101, cylindrical lens 102 focus backward moves in z _T point and x _T, reflection in the focus error detection plane P The cross section of the light beam is thinner in the direction perpendicular to the paper, and thicker in the direction parallel to the paper.
The spot S on the four-division photodiode (a, b, c, d) becomes a horizontally long ellipse in the drawing. In this case, since the output level from one adder 104 is smaller than the output level from the other adder 105, the differential amplifier 106 outputs a signal of a negative level.

The difference signal from the differential amplifier 106 is used as a focusing error signal. For example, the objective lens 101 is moved toward and away from the magneto-optical disk 103 (ie, in a direction approaching and moving away from the magneto-optical disk 103). By supplying the above-mentioned focusing error signal to the drive system of the focus adjustment mechanism moved to the position (1), the light beam can be focused on the magneto-optical disk 103 (see Japanese Patent Publication No. 57-12188). .

Next, the knife edge method is a method in which a knife edge 107 is placed at a focal position z of reflected light as shown in FIG. As shown in FIG. 8B, the magneto-optical disk 103
But when in the focal point of the objective lens 101 is not affected by the knife edge 107, the output from the two-division photodiode D ₁ and D ₂ are D ₁ = D _2. Further, as shown in Figure 8A, when the magneto-optical disc 103 is too close to the objective lens 101, the focal position z of the reflected light becomes z _K away from the knife edge, 2 divided photodiode under the influence of the knife edge 107 D ₁ and D
The output of ₂ is D ₁ > D ₂ .

On the other hand, as shown in FIG. 8C, when the magneto-optical disk 103 is too far from the objective lens 101, the focal position z of the reflected light moves to the objective lens 101 side from the position of the knife edge 107, and z _T Become a knife edge 1
07, the outputs of the two-division photodiodes D ₁ and D ₂ are conversely D ₁ <D ₂ . Therefore, the outputs from the two-division photodiodes D ₁ and D ₂ are supplied to the differential amplifier 106 shown in FIG. 7, and the difference signal from the differential amplifier 106 is focused as in the case of the astigmatism method. By using the light beam as an error signal, the light beam can be focused on the magneto-optical disk 103.

Next, the Foucault method uses a prism in place of the knife edge 107 of the above-described knife edge method. As shown in FIGS. 9A and 9B, the vertex of the prism 108 is located at the focal position z of the reflected light. One of the outputs of the _four photodiodes (D ₁ , D ₂ , D ₃ , D ₄ ) and the outputs of the outer photodiodes D ₁ and D ₄ are added, for example, to one adder 104 shown in FIG. And outputs the outputs of the inner photodiodes D ₂ and D ₃ to the other adder 105.
And using the difference signal from the differential amplifier 106 as a focusing error signal as in the case of the astigmatism method, so that the light beam can be focused on the magneto-optical disk 103. Become.

[0015]

However, in the conventional recording / reproducing apparatus, the reproducing system includes an optical system for detecting a magneto-optical signal, an optical system for detecting the focusing error signal, and an optical system for detecting the tracking error signal. There is a problem in that at least three optical systems of the system are required, and the structure becomes very complicated.

Further, the optical system requires a certain space between the optical components, which is one of the factors that make it impossible to reduce the size and weight of the recording / reproducing apparatus. Therefore, reducing even one optical system leads to simplification of the structure of the recording / reproducing apparatus and reduction in size and weight.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to easily focus a light beam on a disc-shaped recording medium and to construct a reproducing system. Among such optical systems, an optical system for detecting a focusing error signal can be omitted, and recording and / or recording for a disk-shaped recording medium can be realized, which can simplify the structure of the apparatus itself and reduce the size and weight. Another object of the present invention is to provide a playback device.

[0018]

According to the present invention, as shown in FIG. 4, for example, a disc-shaped recording medium 1 is mounted in a recording and / or reproducing apparatus main body for a disc-shaped recording medium, and Rotary drive means 2 for rotating and driving disk-shaped recording medium 1
A recording and / or reproducing means (optical head) for recording and / or reproducing information signals on the disc-shaped recording medium 1 via a light beam, and having an objective lens 13 for focusing the light beam. In the recording and / or reproducing apparatus for a disk-shaped recording medium having the magnetic head 4 and the magnetic head 4), the relative height Δh between the inner circumference and the outer circumference of the disk-shaped recording medium 1 mounted on the rotation drive means 2 is detected. Height detecting means, moving position detecting means for detecting a radial moving position x of the recording and / or reproducing means with respect to the disc-shaped recording medium 1,
The distance a between the objective lens 13 and the disc-shaped recording medium 1 is adjusted based on the relative height signal from the height detecting means and the position signal of the recording and / or reproducing means from the moving position detecting means. And adjustment means (slide mechanism 31 and motor 32) for adjusting the focus of the objective lens 13.

The detecting means is, for example, a disc-shaped recording medium 1.
And a plurality of sensors 21 and 22 for detecting return light from the height detecting discriminators 8 and 9 formed on the inner peripheral side and the outer peripheral side of the information signal recording area 7 (see FIG. 2). Calculating means for obtaining the relative height Δh between the inner circumference and the outer circumference of the disc-shaped recording medium 1 based on the detection signals S ₁ and S ₂ from the _first and _second units (for example, the first differential amplifier 43 in FIGS. 4 and 5) And is provided. Further, the present invention includes offset amount detecting means for detecting a vertical offset amount between the disc-shaped recording medium and the recording and / or reproducing means, and an adjusting means for adjusting the focus of the objective lens 13 (the slide mechanism 31 and the The motor 32) controls the objective lens based on a relative height signal from the height detecting means, a position signal of the recording and / or reproducing means from the moving position detecting means, and a signal from the offset amount detecting means. And the distance between the disc-shaped recording medium and the disc-shaped recording medium.

[0020]

In the recording and / or reproducing apparatus for a disk-shaped recording medium according to the present invention, when, for example, reproducing an information signal from the disk-shaped recording medium 1, first, the disk-shaped recording medium 1 in the rotary driving means 2 is used. The disk-shaped recording medium 1 is mounted on the portion (turntable 11) on which is to be mounted. Thereafter, for example, by operating a reproduction key on the operation panel, the disc-shaped recording medium 1 is rotated, and the recording and / or reproducing means (optical head 3 and magnetic head 4) is moved in the radial direction of the disc-shaped recording medium 1. I do.

At this time, simultaneously with the rotation of the disc-shaped recording medium 1, the discriminating portions 8 and 9 for detecting the heights formed on the inner and outer sides of the information signal recording area 7 of the disc-shaped recording medium 1 are used. Are detected by the sensors 21 and 22. Signals S ₁ and S ₂ output from the sensor 21 and 22, the inner and outer circumference of the disc-shaped recording medium 1 is the height h ₁ and h _2, the arithmetic means 43 of the signal S ₁ and S ₂ By taking the difference, the relative height Δh of the inner circumference and the outer circumference is detected.

From the relative height Δh, recording and / or
Or the focus adjustment amount y of the reproducing means (optical head 3)
_(x) is obtained and the adjusting means (slide mechanism 31 and motor 3
In 2), the distance between the objective lens 13 and the disc-shaped recording medium 1 is adjusted by moving the disc-shaped recording medium 1 up and down in accordance with the obtained focus adjustment amount y _(x). The interval width with the disc-shaped recording medium 1 is stabilized at a predetermined interval width a.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a recording and / or reproducing apparatus for a disk-shaped recording medium according to the present invention (hereinafter simply referred to as a recording / reproducing apparatus).
Will be described with reference to FIGS. 1 to 5. As a disk-shaped recording medium, a magnetic field modulation type magneto-optical recording medium (hereinafter simply referred to as a magneto-optical disk) which has been put to practical use at present.
An embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 1, the recording / reproducing apparatus according to this embodiment includes a spindle motor 2 for rotating and driving a magneto-optical disk 1, an optical head 3 movable in a radial direction of the magneto-optical disk 1, and an optical head 3. It comprises a magnetic head 4 provided on the opposite side of the optical head 3 with the magnetic disk 1 interposed therebetween.

The magneto-optical disk 1 has a rigid substrate 5 made of synthetic resin or glass having a thickness.
The recording layer (perpendicular magnetization film) 6 is formed concentrically with a predetermined width d. Then, as shown in FIG. 2, the portion where the recording layer 6 is formed constitutes an information signal recording area 7. Further, in this embodiment, as shown, light reflection films 8 and 9 made of, for example, aluminum or the like are formed annularly on the inner and outer peripheral sides of the information signal recording area 7, respectively.

A turntable 11 is fixed to the upper end of the rotating shaft 10 of the spindle motor 2. The center core 12 of the magneto-optical disk 1 is clamped by the turntable 11, so that the magneto-optical disk is 1 is mounted on the spindle motor 2.

The optical head 3 is provided with an objective lens 13 on the side facing the magneto-optical disk 1, and condenses a light beam B from a light source (not shown) by the objective lens 13.
It is configured to irradiate the recording layer 6 of the magneto-optical disk 1. In particular, the light beam B is focused on the recording layer 6 in accordance with the condensing characteristics of the objective lens 13,
The separation width between the optical head 3 and the magneto-optical disk 1 is set.

On the other hand, the magnetic head 4 is located above the mounted magneto-optical disk 1 and is movable in the radial direction of the magneto-optical disk 1 in conjunction with the optical head 3.

The recording / reproducing apparatus according to the present embodiment
As shown, for example, a magneto-optical disk 1 mounted on a turntable 11 is mounted on a chassis substrate in the apparatus.
Optical sensors 21 and 22 are fixed and arranged at portions corresponding to the light reflecting films 8 and 9, respectively. Each of the optical sensors 21 and 22 is composed of a combination of a light emitting element and a light receiving element. Light emitted from the light emitting element is reflected by the light reflecting film 8 (and 9) on the magneto-optical disk 1, and the reflected light is reflected by the light reflecting film 8 (and 9). It is configured to be incident on a light receiving element.

The light receiving element has a negative characteristic and outputs a signal current corresponding to the amount of incident reflected light. In other words, the farther the reflective film 8 (and 9) on the magneto-optical disk 1 is from the optical sensor 21 (and 22), the smaller the amount of reflected light becomes, so the output terminal of the optical sensor 21 (and 22) Outputs a high level signal current.

Next, the principle of detecting the runout of the magneto-optical disk 1 in the recording / reproducing apparatus according to this embodiment will be described. The surface of the magneto-optical disk 1 mounted on the turntable 11 is caused by a run-out due to its rotation due to factors such as manufacturing variations. Since the magneto-optical disk itself is formed of a rigid substrate, the relative height between the center core and the inner peripheral side (the inner peripheral side light reflection film) of the recording layer is substantially the same. However, on the outer peripheral side of the recording layer, the following surface runout occurs due to a difference in surface stress due to manufacturing variations. That is, when the instantaneous point of the rotating magneto-optical disk 1 is viewed, for example, as shown in FIG. 3A, the outer circumferential side of the magneto-optical disk 1 is lifted upward from the inner circumferential side, or conversely. As shown in FIG. 3B, the inner peripheral side of the magneto-optical disk 1 is lifted higher than the outer peripheral side.

Also, due to the run-out of the axis of the rotating shaft 10 of the spindle motor or the wave-like deformation generated along the circumference of the magneto-optical disk 1, the optical head 3 is moved in the height direction with respect to the predetermined separation width a. Offset OF may occur. That is, as shown by a two-dot chain line in FIGS. 3A and 3B, when a position above the optical head 3 by a predetermined separation width a is set as the reference position y ₀ , the center core 12 of the magneto-optical disk 1 is more than the reference position y ₀ . It will be located above or below the distance corresponding to the offset OF.

Therefore, in the present embodiment, as shown in FIG. 4, for example, the heights of the inner peripheral light reflecting film 8 and the outer peripheral light reflecting film 9 on the magneto-optical disk 1 are increased by two optical sensors 21 and 22. H ₁ and h ₂ are detected, and the optical sensor 21 on the inner peripheral side is detected.
, Offset OF due to center runout or the above deformation
And the two optical sensors 21 and 22 detect a displacement difference Δh (h ₂ −h ₁ ) between the outer circumference and the inner circumference. Then, when the position of the optical head 3 is a variable x, a motion function represented by the following equation 1 can be obtained from the offset OF and the displacement difference Δh.

[0034]

(Equation 1)

The movement function y _(x) determines the amount of movement of the optical head 3 in the height direction at the current position x. By performing movement based on the movement function y _(x) , 3 can be kept constant at all times. That is, the focus of the objective lens 13 can be adjusted. In general, moving the optical head 3 causes disturbance,
In this embodiment, the optical head 3 is relatively moved by moving the spindle motor 2 in the height direction.

Next, a circuit configuration for realizing the focus adjustment of the optical head 3 based on the detection principle, that is, the motion function y _(x) will be described with reference to FIGS. 4 and 5. Also in the configuration, the spindle motor 2 is provided with a slide mechanism 31 that enables the spindle motor 2 to move in the height direction.

The slide mechanism 31 is a mechanism mainly composed of a motor 32. When the motor 32 is driven to rotate forward, the spindle motor 2 itself moves downward, and the motor 3 rotates.
The spindle motor 2 itself moves upward by the reverse rotation drive of the spindle motor 2. The movement amount of the spindle motor 2 corresponds to the level of the drive voltage supplied to the motor 32. If the drive voltage is at a positive level, the motor 32
The motor 32 is configured to be driven to rotate forward, and if the drive voltage is at a negative level, the motor 32 is driven to rotate in the reverse direction.

First, the circuit configuration shown in FIG. 4 shows an analog real-time control system. This real-time control system receives a detection signal from the optical sensors 21 and 22 at the same time as recording and reproducing an information signal on and from the magneto-optical disk 1 via the optical head 3 and performs a motion corresponding to the motion function y _(x). Is performed by the spindle motor 2.

The circuit configuration shown in FIG. 4 includes a first operational amplifier 41 for converting the signal current S ₁ from the inner peripheral side optical sensor 21 into a voltage and performing in-phase amplification, and a signal current S ₂ from the outer peripheral side optical sensor 22. a second operational amplifier 42 to phase and voltage conversion amplifying the first differential amplifier 43 to take a voltage signal V ₁ of the from the first operational amplifier 41 a difference between the voltage signal V ₂ from the second operational amplifier 42 A second differential amplifier 44 for obtaining a difference between the voltage signal V ₁ from the first operational amplifier 41 and the reference voltage Vr; a differential signal V ₃ from the first differential amplifier 43; A multiplier 46 for multiplying the voltage signal Vx from the multiplier 45 and an adder 47 for summing a multiplication signal V ₄ from the multiplier 46 and a difference signal V ₅ from the second differential amplifier 44. Be composed. Here, the reference voltage Vr is set to a voltage corresponding to a predetermined separation width a between the optical head 3 and the magneto-optical disk 1.

Next, the transfer of signals in the above circuit configuration will be described in accordance with the above detection principle.
From the differential amplifier 43, the difference signal V ₃ showing the displacement difference Δh between the inner and outer peripheries of the magneto-optical disk 1 is output. FIG.
In the example of (or FIG. 3A), since the outer peripheral side is located higher than the inner peripheral side, a positive level difference signal ΔV ₃ is output. In the example of FIG. 3B, the outer peripheral side is located lower than the inner peripheral side. since the results in the difference signal V ₃ of the negative level is output.

[0041] From the second differential amplifier 44, the difference signal V ₅ that indicates the offset OF in accordance with the rotation of the magneto-optical disk 1 is output. In the example of FIG. 4 (or FIG. 3A) and FIG.
Inner circumferential side light-reflecting film 8 in the magneto-optical disc on 1, since it is located above the reference position y _0, so that the difference signal V ₅ of the positive level is output. Incidentally, the inner circumferential side light-reflecting film 8 in the magneto-optical disc on 1, when located below the reference position y _0, above the second differential amplifier 44, the difference signal V ₅ of a negative level is output You.

On the other hand, the variable resistor 45 has a sliding portion 48
Is connected to the optical head 3 and the variable resistor 45
The total resistance R (= R ₁ + R ₂ ) corresponds to the maximum moving distance L of the optical head 3, and the variable resistance R ₂ corresponds to the instantaneous moving distance x of the optical head 3. Therefore, the voltage signal Vx from the variable resistor 45 corresponds to x / L expressed by the above equation (1).

Accordingly, the multiplier 46 outputs the voltage signal V ₄ corresponding to the first term on the right side of the motion function y _(x) shown in the above equation ₍ 1). Then, by adding the difference signal (offset) V ₅ from the second differential amplifier 44 by the adder 47, from the adder 47, the motion function y
_The voltage signal Vy corresponding to _(x) is output.
The voltage signal Vy output from the adder 47 is applied to the motor 32 of the slide mechanism 31 of the spindle motor 2.
By supplying the drive voltage signal, the spindle motor 2 can perform a motion corresponding to the motion function y _(x) , and the runout and offset of the magneto-optical disk 1 accompanying the rotation of the magneto-optical disk 1 are caused. Can be absorbed.

That is, as the optical head 3 moves in the radial direction of the magneto-optical disk 1, the magneto-optical disk 1 is moved so that the interval between the optical head 3 and the magneto-optical disk 1 becomes a predetermined interval a. Moves up and down, and the optical head 3
The focal point of the light beam emitted from the optical disk is always focused on the recording layer 6 (see FIG. 1) of the magneto-optical disk 1.

Next, an example of a circuit configuration based on the digital control method will be described with reference to FIG. Note that components corresponding to those in FIG. 4 are denoted by the same reference numerals. This digital control system reads the runout and offset of the magneto-optical disk 1 using the initial rotation performed when the magneto-optical disk 1 is mounted on the turntable 11, and outputs the information signal via the optical head 3. During recording and reproduction, the spindle motor 2 is moved up and down based on the data read in advance as described above.

As shown in the diagram, the circuit configuration is such that the difference signal Vh from the first differential amplifier 43 is
h, a second A / D converter 52 for converting the difference signal Vo from the second differential amplifier 44 into digital data Do, reading of various data, Control unit 53 that performs writing and controls each circuit
A calculation unit 54 for performing a desired calculation based on the data supplied from the control unit 53; and a D / A converter 55 for converting the calculation result from the calculation unit 54 into an analog signal.

The reproduction signal S from the optical head 3 is
The data is converted into digital data D by the A / D converter 56 in the middle and supplied to the control unit 53. In particular, the reproduced data D is attributed to the magneto-optical disk 1 (for example, each start address and end of the recorded information group). TO indicating the address and number of information)
In the case of C data, T (not shown)
It is registered in the OC data memory. At the time of reading the TOC data, the control unit 53 permits interruption of the data Dh and Do from the first and second A / D converters at the stage when the head address of the TOC data is detected. This is performed in order to determine a reference point in detecting the surface runout and offset of the magneto-optical disk 1.

The control unit 53 reads data Dc from the counter 57. The counter 57 includes an optical head servo control circuit 58 that servo-controls the optical head 3.
This circuit counts a control signal (a signal output while the optical head 3 is moved in the radial direction of the magneto-optical disk 1) by a clock signal CLK input separately. The data Dc is
The data corresponds to the moving distance x of the optical head 3.

Then, at the time of initial rotation of the magneto-optical disk 1,
The control unit 53 controls a timing signal St from a spindle servo control circuit 59 for performing servo control of the spindle motor 2.
Based on the first and second A / D converters 51 and 52
, Respectively, and reads the data Dh and Do, respectively, and cyclically registers them in the memory 60 for creating a motion function. In this memory 60, a displacement difference data area and an offset data area are logically allocated corresponding to each data Dh and Do.

The timing signal St from the servo control circuit 59 is a signal for outputting, for example, 256 pulses during one rotation of the rotating shaft 10 of the spindle motor 2. In the data area, 256 sampling data are registered. Also, the sampling frequency in the first and second A / D converters 51 and 52 is set to be the same as the frequency of the timing signal St.

Next, the operation of the recording / reproducing apparatus of the digital control system shown in FIG. 5 will be described. First, the control unit 53
Inhibits interruption of data Dh and Do sent from the first and second A / D converters 51 and 52. When the magneto-optical disc 1 is mounted on the turntable 11 of the spindle motor 2, the spindle motor 2 is driven to rotate, thereby rotating the magneto-optical disc 1 (initial rotation). During this initial rotation, for example, the optical head 3
Through which the attribute of the magneto-optical disk 1 is recorded
The above attribute is read from the OC data area as a TOC signal S. The TOC signal S is converted into digital data (TOC data) D by an A / D converter 56 at the subsequent stage and supplied to the control unit 53. The control unit 53 detects the start address of the TOC data D supplied from the A / D converter 56, and when the start address is detected, the first and second A / D converters 51 and 52. Interrupts of the data Dh and Do sent from the server are permitted.

When the interrupt is enabled, the control unit 53
Reads the data Dh and Do from the first and second A / D converters 51 and 52 based on the timing signal St from the servo control circuit 59, and reads the read data D
h and Do are cyclically registered in the memory 60 at the same timing. As a result, the data Dh and Do regarding the surface deflection and offset of the magneto-optical disk 1 are read. When the reading of the data Dh and Do is completed, the initial rotation of the magneto-optical disk 1 stops.

Next, for example, when the operator operates a reproduction key on an operation panel (not shown), the magneto-optical disk 1 is rotated again, and the optical head 3 (and the magnetic head 4 (see FIG. 1)) is turned on. It moves in the radial direction of the magnetic disk 1. At this time, the control unit 53 controls the servo control circuit 5
9 from the memory 60 based on the timing signal St from the memory 9 (displacement difference data Dh and offset data Dh).
o) is read cyclically, and further, the count data Dc is read from the counter 57 based on the timing signal St, and is supplied to the arithmetic unit 54.

The operation unit 54 receives the supplied displacement difference data D
h, the offset data Do, the count data Dc, and the fixed function data (count data corresponding to the maximum moving distance L of the optical head 3) stored in the arithmetic unit 54, the motion function value (spindle The vertical movement amount Dy of the motor is obtained.

The calculation result (function value) Dy in the calculation unit 54 is supplied to the D / A converter 55 via the control unit 53, and the D / A converter 55 converts the Dy into a voltage signal Vy. It is supplied to the motor 32 of the slide mechanism 31. These series of operations are performed at the output timing of each pulse of the timing signal St, and data Dh, Do, and Dc are supplied to the arithmetic unit 54 every time a pulse is input, and the supplied data Dh, Do, and Dc are supplied. Is calculated based on the equation (2), and the function value Dy is supplied to the motor 32 as a voltage signal Vy (ie, a drive voltage signal).

The motor 32 receives the supplied drive voltage signal V
spindle motor 2 based on the voltage level and polarity of y
Move up and down. This allows the optical head 3 to move in the radial direction of the magneto-optical disk 1 and the optical head 3 to move.
The magneto-optical disk 1 moves up and down so that the interval between the optical disk 1 and the magneto-optical disk 1 becomes a predetermined interval width a, and the focus of the light beam emitted from the optical head 3 is always This is suitable for one recording layer 6 (see FIG. 1).

As described above, according to the recording / reproducing apparatus of the present embodiment, the light reflecting films 8 and 9 are formed on the inner and outer circumferences of the information signal recording area 7 of the magneto-optical disk 1, and are provided in the apparatus. The optical sensors 21 and 22 detect the relative height Δh and the offset OF of the light reflecting films 8 and 9 to detect surface runout and core runout due to the rotation of the magneto-optical disk 1, and the detected surface runout is detected. Since the spindle motor 2 is moved up and down so as to cancel the core runout, the focus of the light beam from the optical head 3 can be easily adjusted to the recording layer 6 of the magneto-optical disk 1. That is, the objective lens 1
3 can be easily adjusted.

Unlike the conventional method of performing focus adjustment using the reproduction light of the optical head 3, the detection signals S ₁ and S ₂ from the optical sensors 21 and 22 provided outside the optical head 3 are used. Since the focus is electrically adjusted based on this, the structure of the optical system of the optical head 3 can be simplified, and the optical head 3 can be manufactured with a simple configuration. Accordingly, the structure of the recording / reproducing apparatus itself can be simplified, and the reduction in size and weight can be further promoted as compared with the conventional case.

In the above-described embodiment, an example in which the recording / reproducing apparatus is applied to the magneto-optical disk 1 of the magnetic field modulation type has been described. Alternatively, the magneto-optical disk of the light modulation type, the rewritable optical disk, or the read-only optical disk (CD-
ROM).

[0060]

As described above, according to the recording and / or reproducing apparatus for a disk-shaped recording medium according to the present invention, the relative height between the inner circumference and the outer circumference of the disk-shaped recording medium mounted on the rotary drive means. Detecting means for detecting the position of the recording and / or reproducing means in the radial direction with respect to the disk-shaped recording medium; a relative height signal from the height detecting means and a moving position detecting stage. And an adjusting means for adjusting the distance between the objective lens and the disc-shaped recording medium based on the position signal of the recording and / or reproducing means to adjust the focus of the objective lens. The light beam can be focused on the disc-shaped recording medium, and the optical system for detecting the focusing error signal can be omitted from several optical systems constituting the reproducing system. Structure It is possible to realize simplification of and reduction in size and weight.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a recording and / or reproducing apparatus for a disc-shaped recording medium according to the present invention (hereinafter, simply referred to as a recording and reproducing apparatus according to the present embodiment).

FIG. 2 is a plan view showing a magneto-optical disk mounted on the recording / reproducing apparatus according to the embodiment.

FIG. 3 is an explanatory diagram showing a surface deflection and a core deflection of the magneto-optical disk accompanying rotation of the magneto-optical disk.

FIG. 4 is a circuit block diagram illustrating an example of a circuit configuration of the recording / reproducing apparatus according to the embodiment.

FIG. 5 is a circuit block diagram showing another example of the circuit configuration of the recording / reproducing apparatus according to the embodiment.

FIG. 6 is an explanatory diagram showing a principle of detecting a focusing error signal by an astigmatism method.

FIG. 7 is a circuit block diagram showing an example of a circuit configuration for detecting a focusing error signal.

FIG. 8 is an explanatory diagram showing a principle of detecting a focusing error signal by the knife edge method.

FIG. 9 is an explanatory diagram showing a principle of detecting a focusing error signal by the Foucault method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magneto-optical disk 2 Spindle motor 3 Optical head 4 Magnetic head 5 Substrate 6 Recording layer 7 Information signal recording area 8, 9 Light reflection film 10 Rotation axis 11 Turntable 12 Center core 13 Objective lens 21, 22 Optical sensor 31 Slide mechanism 32 Motors 41, 42 Operational amplifiers 43, 44 Differential amplifiers 45 Variable resistors 46 Multipliers 47 Adders 51, 52 A / D converters 53 Control units 54 Operation units 55 D / A converters 57 Counters

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-71941 (JP, A) JP-A-61-938 (JP, A) JP-A-4-170734 (JP, A) JP-A-Heisei 4- 114326 (JP, A) JP-A-4-321968 (JP, A) JP-A-1-116918 (JP, U) JP-A-2-117760 (JP, U) JP-A-1-133316 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G11B ^7/ 09-7/10 G11B 19/00-19/28

Claims (3)

(57) [Claims] 1. A recording and / or reproducing apparatus for a disk-shaped recording medium, wherein a disk-shaped recording medium is mounted in the main body, and rotation driving means for driving the mounted disk-shaped recording medium to rotate; Recording and / or reproduction of an information signal on a medium via a light beam, and recording and / or reproducing means for a disc-shaped recording medium having recording and / or reproducing means provided with an objective lens for focusing the light beam. And / or a reproducing apparatus, wherein a height detecting means for detecting a relative height between an inner circumference and an outer circumference of the disc-shaped recording medium mounted on the rotary drive means, and the disc-shaped recording medium of the recording and / or reproducing means To
A moving position detecting means for detecting a movement position in the radial direction, relative height signal and the movement position detection from the height detecting means
Adjusting means for adjusting the distance between the objective lens and the disc-shaped recording medium based on the position signal of the recording and / or reproducing means from the output means to adjust the focus of the objective lens. A recording and / or reproducing apparatus for a disc-shaped recording medium. 2. A plurality of sensors for detecting return light from a height detecting discriminator formed on an inner peripheral side and an outer peripheral side of an information signal recording area in the disc-shaped recording medium, 2. The disk-shaped recording medium according to claim 1, further comprising: an arithmetic unit for calculating a relative height between an inner circumference and an outer circumference of the disk-shaped recording medium based on a detection signal from each sensor. Recording and / or playback device for media. 3. The recording and / or reproducing apparatus further comprises an offset amount detecting means for detecting a vertical offset amount between the disc-shaped recording medium and the recording and / or reproducing means, and the height detecting means A distance between the objective lens and the disc-shaped recording medium based on a relative height signal from the means, a position signal of the recording and / or reproducing means from the moving position detecting means, and a signal from the offset amount detecting means. Adjusting means for adjusting the focus of the objective lens by adjusting the focal length of the objective lens.
A recording and / or reproducing apparatus for the disc-shaped recording medium according to the above.