JP3062064B2 - Optical disk motion characteristics measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk motion characteristic measuring device capable of improving the measurement accuracy.

[0002]

2. Description of the Related Art A recording track is formed on an information recording surface of an optical disk in a radial direction thereof. Recording, reproduction, and erasure of information on the recording track are performed by an optical head. The optical head focuses and irradiates a beam for recording, reproducing and erasing information on a recording track of a rotating optical disk as a minute spot, and based on a change in the beam reflected from the information recording surface of the optical disk, information is obtained. Record, play back, and erase.

[0003] Here, the optical head is always accurately positioned on the recording track even when the optical disk itself is warped, the surface undulates due to the rotation of the optical disk, and the vibration based on the inherent vibration system of the optical disk itself. Since it is necessary to focus the beam, the objective lens for focusing the beam is slightly moved (focus servo) in the optical axis direction.

Further, the optical head is required to precisely track the recording track by the spot even when the recording track is eccentric, so that the objective lens is minutely moved (tracking servo) in the radial direction of the optical disk. ing.

[0005] Such a conventional optical head is disclosed in, for example, Japanese Patent Publication No. 5-68013 and Japanese Patent Laid-Open No. 4-31.
9537, JP-A-62-265243 and JP-A-4-
There is a method proposed in 324127 and the like.

As described above, the optical head performs the recording, reproduction, and erasing of information by causing the objective lens to follow the movement of the rotating optical disk in the focus direction and the tracking direction. In order to apply the servo and the tracking servo, it is necessary to optically accurately measure the movement characteristics of the optical disk itself.

Therefore, conventionally, an optical disk motion characteristic measuring device as shown in FIGS. 9 and 10 has been used.
9A and 9B show a conventional apparatus for measuring the motion characteristics of an optical disk, wherein FIG. 9A is a side sectional view, and FIG. 9B is a sectional view taken along line XX of FIG. 9A. FIG. 10 is a circuit diagram showing a capacitance detection type actuator of the above-mentioned kinetic characteristic measuring apparatus.

This conventional optical disk motion characteristic measuring apparatus measures the motion characteristics of an objective lens that follows a rotating optical disk, assuming the optical characteristics of the optical disk, and obtains the optical disk motion characteristics based on the optical disk motion characteristics. Was something. It should be noted that the measurement of the motion characteristics of the objective lens without directly measuring the motion characteristics of the optical disc is performed by:
This is because the tracking axis or the focus axis can be easily separated, and as a result, the objective lens is operated by a two-axis or three-axis actuator, which is effective for obtaining motion characteristics.

In FIGS. 9A and 9B, reference numeral 101 denotes an objective lens, which is an objective lens holder 10 made of a magnetic material.
2 This objective lens holder 102
The lens tube 1 is connected via the vertical parallel leaf springs 103, 103.
04 is movably supported in the tracking direction. Electromagnetically drives the objective lens 101 in the tracking direction.
And the conductor 105a facing the conductor 102a was adhered to the fixed yoke 105 surrounding the objective lens holder 102.

Further, the lens tube 104 is supported on both sides thereof by horizontal parallel leaf springs 106, 106. To electrically drive the objective lens 101 in the focus direction, a conductor 104a is provided on the bottom surface of the lens tube 104. At the same time, the conductor 104 is attached to the housing 107.
The conductor 107a opposed to a was adhered.

In FIG. 10, reference numeral 110 denotes a capacitance detection type actuator, which is a conductor 104a and a conductor 107a.
And the lens tube 10 as described below.
4 (objective lens 101) in the focus direction. Note that a similar capacitance detection type actuator for detecting the displacement of the objective lens holder 102 (objective lens 101) in the tracking direction is also connected to the conductor 102a and the conductor 105a. Only the capacitance detection type actuator 110 for detecting the displacement in the focus direction will be described.

The capacitance detection type actuator 110 mainly includes four capacitors C ₁ and C 4 connected to the conductors 104 a and 107 a via a coaxial cable 111.
It was formed by a capacitor bridge 112 consisting of ₂ , C ₃ and C _V. The capacitor C _V is a variable capacitor that adjusts the balance of the bridge.
The capacitor C ₁ and capacitor C _3, outgoing output of 3.5MHz is had been connected.

[0013] In the capacitance detection-type actuator 110 having such a configuration, the relay point and the contact point between the capacitors C ₁ and C ₂ of the capacitor C ₃ and C _V, the change in capacitance between the conductor 104a and the conductor 107a Based on this voltage, the displacement of the lens tube 104 (the displacement of the objective lens 101 in the focus direction) proportional to the change in the capacitance is measured based on this voltage.

[0014]

However, the above-mentioned conventional apparatus for measuring the movement characteristics of an optical disk is composed of a conductor 104a.
And the conductor 107a (the conductor 102a and the conductor 105
a) on the basis of the change in the capacitance during a)
01, the displacement in the tracking direction and the focus direction is detected, so that the turbulence of the air flow generated when the objective lens 101 or the like moves becomes a disturbance, and the movement characteristics of the objective lens 101 can be accurately measured. There was a problem that it was not possible.

In the measurement based on the change in electric capacitance between the conductor 104a and the conductor 107a, the measurement accuracy is ± 1.
There is a problem that only a measurement accuracy of about μm can be obtained, and the movement characteristics of the objective lens cannot be measured with high accuracy.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and greatly improves the accuracy of measuring the motion characteristics of an objective lens by measuring the motion speed of the objective lens using the laser Doppler effect. It is an object of the present invention to provide a device for measuring the motion characteristics of an optical disc which can be used.

[0017]

In order to achieve the above object, an apparatus for measuring the movement characteristics of an optical disk according to claim 1 is provided.
An apparatus for measuring a movement characteristic of an optical disk based on a movement speed of an objective lens during rotation driving of the optical disk, the objective lens holder holding the objective lens and swingably disposed on a lower surface of the optical disk; A first reflector attached to one side surface of the objective lens holder, a second reflector attached to the back surface of the objective lens holder, and emits a beam to the first reflector, from the first reflector A first reference light type laser Doppler measurement meter for detecting the movement speed of the objective lens holder in the tracking direction based on the reflected light, and emits a beam to the second reflector,
A second reference light type laser Doppler measurement meter that detects a moving speed of the objective lens holder in a focus direction based on the reflected light from the second reflector, A 45-degree mirror for changing the direction of the beam emitted from the second reference light type laser Doppler measuring instrument by 45 degrees to be incident on the second reflector, and an objective lens detected by the first reference light type laser Doppler measuring instrument The moving speed of the objective lens is obtained based on the moving speed of the holder in the tracking direction and the moving speed of the objective lens holder in the focus direction detected by the second reference light type laser Doppler meter.

According to this structure, the displacement of the objective lens holder (ie, the objective lens) in the tracking direction and the focus direction is detected based on the moving speed of the objective lens holder, and the laser Doppler effect is used. Since the movement speed of the objective lens holder is measured, the measurement accuracy of the movement characteristics of the objective lens holder can be improved to 0.001 μm or less.

The motion characteristics measuring device of an optical disk according to claim 2, wherein, based on the movement speed of the objective lens during optical disk rotation driving, an apparatus for measuring the motion characteristics of the optical disc, holds the objective lens, the optical disk An objective lens holder swingably disposed on the lower surface of the objective lens holder, a first reflector attached to one side surface of the objective lens holder, a second reflector attached to the back surface of the objective lens holder, A third reflector attached to one side of the support of the lens holder, a fourth reflector attached to the back side of the support, and a beam emitted to the first and third reflectors. And a first differential laser Doppler for detecting a difference between a moving speed of the objective lens holder and the optical base in a tracking direction based on each reflected light from the third reflector. A constant meter and emits a beam to the second and fourth reflectors, and based on each reflected light from these second and fourth reflectors, the movement speed of the objective lens holder and the optical base in the focusing direction. The second differential type laser Doppler measurement meter for detecting the difference and the second and fourth reflectors are located opposite to each other, and each beam emitted from the second differential type laser Doppler measurement direction is directed at 45 degrees. A 45-degree mirror that is incident on the second and fourth reflectors, and the movement speed of the objective lens holder in the tracking direction detected by the first differential laser Doppler meter; The moving speed of the objective lens is obtained based on the moving speed in the focus direction of the objective lens holder detected by the laser Doppler meter.

According to such a configuration, for example, when the base on which the optical disk driving motor and the optical head are mounted is elastically supported, external vibration (driving) is applied to the entire objective lens actuator. The vibration of the objective motor is transmitted, the difference between the movement speed of the objective lens holder and the movement speed of the support of the objective lens holder is detected. Is removed, and only the movement characteristics of the objective lens holder can be accurately measured.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of an apparatus for measuring the motion characteristics of an optical disk according to the present invention will be described with reference to the drawings. First, an optical disk motion characteristic measuring device according to a first embodiment of the present invention will be described. FIG. 1 is an explanatory diagram showing an apparatus for measuring the movement characteristics of an optical disc according to the first embodiment of the present invention. FIG. 2 is a perspective view showing an objective lens actuator of the motion characteristic measuring device, and FIG. 3 is a lower perspective view of the objective lens actuator. FIG. 4 is a view showing an optical system of a reference light type laser Doppler measurement meter used in the above-mentioned motion characteristic measuring apparatus.

In FIG. 1, an optical disk motion characteristic measuring apparatus 1 according to the present embodiment mainly comprises an optical head 2, a positioner 3, a measuring section 4, a motor 5 for driving the optical disk, and a chassis 6.

As shown in FIG. 1, the optical head 2 includes an objective lens actuator 2a and an optical base 2b, and the objective lens actuator 2a is mounted on the positioner 3 via the optical base 2b. The positioner 3 enables the optical head 2 to move in the radial direction of the optical disk.

As shown in FIG. 2, the objective lens actuator 2a is mounted on an optical base 2b, and includes an objective lens 21, an objective lens holder 22 for holding the objective lens 21, and an objective lens holder 22. And a magnet stand 23 for driving the camera in the tracking direction and the focusing direction.

As shown in FIGS. 2 and 3, the objective lens holder 22 has a focus coil 22a and a tracking coil 22b on its side, and is provided with four spring bronze wires 23b having a spring property. Is swingably connected to one side.

A cross-shaped first reflecting plate 22c also serving as a mounting portion for a wire 23b is mounted on a side surface of the objective lens holder 22 on the measuring portion 4 (see FIG. 1) side, as shown in FIG. On the back surface of the objective lens holder 22, a second reflection plate 22d is attached. Here, the reason why the first reflecting plate 22c is formed in a cross shape is that a bonding (soldering) area for firmly fixing the wire 23b is secured, and the wire when the objective lens holder 22 is moved in the focus direction. This is because the contact portion of 23b is cut out to make the movement of the objective lens holder 22 in the focus direction smooth.

Further, a base 45 of the magnet stand 23 reflects a beam from a second reference light type laser Doppler measurement meter 4b, which will be described later, to a second reflection plate 22d.
A mirror 24 is attached. This 45 degree mirror 24
Is such that its reflection surface faces the second reflection plate 22d and does not interfere with the objective lens entrance aperture 22e.

As shown in FIG. 1, the measuring section 4 comprises a first reference light type laser Doppler measuring meter 4a for measuring the moving speed of the objective lens holder 22 in the tracking direction, and the moving speed of the objective lens holder 22 in the focus direction. And a second reference light type laser Doppler measurement meter 4b for measuring the

Here, the structure of the first and second reference light type laser Doppler meters 4a and 4b will be described with reference to FIG. The first and second reference light type laser Doppler meters 4a and 4b are used to measure the beam incidence target (first reflection plate 22c and second reflection plate 22d) and the measurement target (moving speed in the tracking direction and focus direction). Only the movement speed) is different, and the optical system has almost the same configuration.

In FIG. 4, a first reference light type laser Doppler measurement meter 4a (second reference light type laser Doppler measurement meter 4a) is used.
b) the laser light source 41, the first polarization beam splitter 4
2. Second polarization beam splitter 43, 45 degree mirror 4
4, Acousto-Optic-Modulator (AOM)
45, a third polarization beam splitter 46, a light receiver 47, an optical fiber 48, and a sensor head 49.

The beam emitted from the laser light source 41 is
The beam is split into two beams by the first polarizing beam splitter 42, and one beam is
2 and the other beam is reflected by the first polarizing beam splitter 42.

The beam transmitted through the first polarizing beam splitter 42 enters a sensor head 49 via a second polarizing beam splitter 43 and an optical fiber 48, and is focused by a focusing lens built in the sensor head 49 on a first reflector. The light is condensed on 22c (second reflector 22d). Thereby, the reflected light from the first reflector 22c is transmitted to the sensor head 4
9 and the second polarization beam splitter 43 via the optical fiber 48. The reflected light is reflected by the second polarization beam splitter 43, is reflected by the 45-degree mirror 44, and is incident on the third polarization beam splitter 46.

On the other hand, the beam reflected by the first polarizing beam splitter 42 (hereinafter referred to as reference light) is switched by the acousto-optic modulator 45, then reflected by the third polarizing beam splitter 46, and is reflected by the first reflector. 22c
Multiplexed with the reflected light from

Thereafter, the interference output between the reflected light and the reference light is detected by the light receiver 47, and based on this, the movement speed of the first reflector 22c, that is, the objective lens holder 2 is detected.
2 in the tracking direction (in the case of the second reference light type laser Doppler measurement meter 4b, the second reflector 2
The movement speed of 2d, that is, the movement speed of the objective lens holder 22 in the focus direction is detected).

In this manner, the velocity data of the first and second reflectors 22c, 22d measured by the first and second reference light type laser Doppler meters 4a, 4b are integrated by the FFT analyzer to obtain the objective. It is converted into the displacement (movement characteristics) of the lens holder 22, and the movement characteristics of the optical disk 7 are obtained based on the displacement of the objective lens holder 22.

Here, the principle of detecting the movement speed of the first and second reference light type laser Doppler meters 4a and 4b will be described.
This will be described with reference to FIG.

Doppler shift amount (Doppler frequency) = f
_D , the movement speed of the first reflector 22c (or the second reflector 22c
d) = V, wavelength of irradiation light = λ, f _D
= 2 · V / λ.

Here, assuming that the frequency of the beam emitted from the laser light source 41 is f ₀ , the frequency of the light reflected from the first reflector 22c is f ₀ + f _D. The laser light source used for laser Doppler meter is, HeNe lasers are common, because the stability of the wavelength is very good, the motion velocity of the Doppler frequency f _D and the first reflector 22c is a proportional relationship Become.

[0039] Normally, the frequency of the laser light is very high, it is difficult to measure this directly, the detection of the Doppler frequency f _D is reflections by interference frequency f ₀ of the beam emitted from the laser light source 41 This is performed based on the light frequency f ₀ + f _D. The reflected light from the first reflector 22c is
A Doppler shift occurs according to the vibration speed of the first reflector 22c, and the frequency f ₀ ± f _{D of} the reflected light and the frequency f ₀ + f _{M of} the reference light to which the frequency shift is given by the acousto-optic modulator 45 , The beat frequency can be obtained.

Since the reference light is generated in the apparatus, it does not cause a Doppler shift, and the beat frequency is f
_M ± f _D, and the positive and negative Doppler frequency, i.e., it is possible to determine the vibration direction and the vibration velocity is reciprocated.

FIG. 5 shows an example of the movement characteristic of the objective lens holder 22 in the focus direction.

[0042] As shown in the figure, an objective lens actuator 2a of the present embodiment, when the primary resonance frequency f ₀₁ or more frequencies, having an acceleration of magnitude surpassing motion characteristics 200 of the optical disc, and the primary resonance When the frequency is lower than the frequency f ₀₁ , the optical disk has a movable range larger than the displacement of the optical disk.
It is designed to be able to measure the movement of the subject with good reproducibility.

The objective lens actuator 2a is
By setting the secondary resonance frequency _f0n as high as possible, the displacement of the optical disk 7 can be measured faithfully. In the present embodiment, the primary resonance frequency f _{01 is set} to 40 Hz, and the secondary resonance frequency f _{0n is set} to 40 kHz. This makes it possible to measure the motion characteristics of the optical disk 7 up to a frequency that is 1/5 of the secondary resonance frequency _f0n .

According to the apparatus for measuring the movement characteristics of the optical disk of the first embodiment having such a configuration, the displacement of the objective lens holder 22 (that is, the objective lens 21) in the tracking direction and the focus direction is determined by the objective lens holder 22.
In addition to the detection based on the movement velocity of the objective lens holder 22, the movement velocity of the objective lens holder 22 is measured using the laser Doppler effect. be able to.

Next, an apparatus for measuring the movement characteristics of an optical disk according to a second embodiment of the present invention will be described. FIG. 6 is an explanatory diagram showing a motion characteristic measuring device for an optical disc according to the second embodiment of the present invention. FIG. 7 is a perspective view showing an objective lens actuator of the motion characteristic measuring device, and FIG. 8 is a diagram showing an optical system of a differential laser Doppler measuring meter used in the motion characteristic measuring device.

The apparatus for measuring the motion characteristics of an optical disk according to the present embodiment employs a differential type laser Doppler measuring meter, and has a structure in which a base on which an optical disk drive motor and an optical head are mounted is elastically supported. However, the vibration of the drive motor applied to the entire objective lens actuator is removed so that only the movement characteristics of the objective lens holder can be accurately measured.

In FIG. 6, the optical disk of this embodiment is
In the motion characteristic measuring device 1, both the drive motor 5 of the optical disk 7 and the optical head 2 are mounted on a positioner (base) 3, and the positioner 3 is elastically supported by a damping mechanism 10. Has become.

As shown in FIG. 7, the objective lens holder 22
A first reflector 22c and a second reflector 22d (see FIG. 3) similar to those of the first embodiment are attached to the first embodiment. In this embodiment, the third reflector 23c is attached to one side of the magnet stand 23, which is a support for the objective lens holder 22, and the fourth reflector 23d is attached to the back surface of the base of the magnet stand 23. There is.

Further, as shown in FIG.
A first differential laser Doppler measurement meter 8a for measuring the movement speed of the objective lens holder 22 in the tracking direction, and a second differential laser Doppler measurement meter 8b for measuring the movement speed of the objective lens holder 22 in the focusing direction. Has become.

The operation of the first and second differential laser Doppler meters 8a and 8b will now be described with reference to FIG. The first and second differential laser Doppler meters 8a and 8b are used for beam incidence (first and third reflectors 22c and 23c and second and fourth reflectors 22d and 23d) and a measurement object. (Movement speed in the tracking direction and movement speed in the focus direction) are different, and the optical systems have almost the same configuration.

In FIG. 8, the first differential laser Doppler measurement meter 8a (or the second differential laser Doppler measurement meter 8a) is used.
b) The beam emitted from the laser light source 81 (frequency =
f ₀ (hereinafter referred to as a beam f ₀ ) is split into two beams by a first polarizing beam splitter 82, one of which passes through the first polarizing beam splitter 82, and the other beam is a first polarizing beam splitter 82. Is reflected by

The beam transmitted through the first polarization beam splitter 82 passes through the second polarization beam splitter 83 and the optical fiber 91 to the first sensor head 93 (the third sensor in the case of the second differential laser Doppler measurement meter 8b). Head 95)
And is focused on the first reflector 22c (the second reflector 22d in the case of the second differential laser Doppler measurement meter 8b) by the focusing lens built in the sensor head 93.

Thus, the reflected light from the first reflector 22c (frequency = f ₀ ± f _D2 , f _D2 = shift frequency of the reflected light, hereinafter referred to as reflected light f ₀ ± f _D2 ) is _{transmitted to} the first sensor head. The light enters the second polarization beam splitter 83 via the optical fiber 93 and the optical fiber 91. This reflected light f ₀ ± f _D2 is
After being reflected by the second polarizing beam splitter 83, the light is reflected by the 45-degree mirror 84 and the third polarizing beam splitter 86.
Is incident on.

On the other hand, the beam reflected by the first polarization beam splitter 82 (frequency = f ₀ ± f _D1 , f _D1 = shift frequency of reference light, hereinafter referred to as reference light f ₀ ± f _D1 ) is _{transmitted to} the optical fiber 92. Through the second sensor head 94 (fourth sensor head 96 in the case of the second differential laser Doppler measurement meter 8b) and the third reflector 23c (in the case of the second differential laser Doppler measurement meter 8b) Are collected on the fourth reflector 23d).

Thus, the reference light f ₀ ± f _D1 reflected by the third reflector 23c enters the acousto-optic modulator 85 via the second sensor head 93, the optical fiber 92, and the first polarization beam splitter 83. Is done. Then, the reference light f ₀ ± f _D1 is switched by the acousto-optic modulator 45 to become the reference light f ₀ ± f _D1 ± f _M , then reflected by the third polarization beam splitter 86, and It is multiplexed with the reflected light f ₀ ± f _D2 from 22c.

[0056] Then, the light receiver 87, these reference light frequency f ₀ ± f _D1 ± f _M and the reflected light of the frequency f ₀ ± f
Detecting a beat frequency f _M ± f _D1 ± f _D2 is the interference output of the _D2. When only the frequency components that have been Doppler shifted by the detection circuit are extracted from the beat frequencies f _M ± f _D1 ± f _D2 , the shift frequency is the difference between the respective shift frequencies of the reference light and the reflected light (± f _D1 ± f _D2 ). Therefore, the vibration difference between the first reflector 22c and the third reflector 23c, that is,
Only the movement velocity of the objective lens holder 22 in the tracking direction, excluding the vibration of the drive motor 5 applied to the entire objective lens actuator 2a, is detected.

Similarly, in the case of the second differential laser Doppler measurement meter 8b, the second reflector 22d and the third reflector 2d are used.
The vibration difference of 3d, that is, the objective lens actuator 2
Only the movement speed of the objective lens holder 22 in the focus direction excluding the vibration of the driving motor 5 applied to the entirety is detected.

As described above, the vibration difference data between the first reflector 22c and the third reflector 23d measured by the first and second differential laser Doppler meters 8a and 8b, and the second reflector 22d The vibration difference data of the third reflector 23d is expressed as F
By integrating the FT analyzer, into a displacement of the objective lens holder 22 (movement characteristics), based on the displacement of the objective lens holder 22, luck of the optical disk 7
Find dynamic characteristics.

According to the optical disk motion characteristic measuring apparatus of the second embodiment having such a configuration, even when the base on which the drive motor 5 of the optical disk 7 and the optical head 2 are mounted is elastically supported, By removing the vibration of the driving motor 5 applied to the entire objective lens actuator 2a, only the motion characteristics of the objective lens holder 22 can be accurately measured.

Further, since the moving speed is detected by the differential laser Doppler measurement meter, the differential speed in the tracking direction and the focusing direction can be obtained, and interference between the tracking direction and the focusing direction can be easily performed. Can be measured.

It should be noted that the motion characteristic measuring device for an optical disk of the present invention is not limited to the above embodiments. For example, the shape of the first reflector 22c is not limited to the cross shape, and can be changed to another shape such as a rectangle like the third reflector 23c. However, when the first reflector 22c has a cross shape, as described above, the objective lens holder 22
Has the advantage that the movement in the focus direction becomes smooth.

In addition, it is also possible to adopt a configuration in which the beams are directly incident on the second and fourth reflectors 22d and 23d without providing the 45-degree mirrors 24 and 25. Furthermore, the mounting positions of the third reflector 23c and the fourth reflector 23d are not limited to the magnet stand 23, but may be
If the support is a member of another type (for example, the optical base 2)
b).

[0063]

As in the above, according to the present invention, luck of the optical disk according to the present invention
According to the dynamic characteristic measuring device, the measurement accuracy of the kinetic characteristics of the objective lens can be significantly improved by measuring the kinetic speed of the objective lens using the laser Doppler effect.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a motion characteristic measuring device for an optical disc according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing an objective lens actuator of the motion characteristic measuring device.

FIG. 3 is a lower perspective view of the objective lens actuator.

FIG. 4 is a diagram showing an optical system of a reference light type laser Doppler measurement meter used in the motion characteristic measuring device.

FIG. 5 shows an example of a movement characteristic of the objective lens holder 22 in a focus direction.

FIG. 6 is an explanatory view showing a motion characteristic measuring device for an optical disc according to a second embodiment of the present invention.

FIG. 7 is a perspective view showing an objective lens actuator of the motion characteristic measuring device.

FIG. 8 is a diagram showing an optical system of a differential laser Doppler measurement meter used in the motion characteristic measuring device.

9A and 9B show a conventional apparatus for measuring the motion characteristics of an optical disk, wherein FIG. 9A is a side sectional view, and FIG. 9B is a sectional view taken along line XX of FIG. 9A.

FIG. 10 is a circuit diagram showing a capacitance detection type actuator of the motion characteristic measuring device.

[Explanation of symbols]

1: Optical disk motion characteristic measuring device 2: Optical head 2a: Objective lens actuator 4, 8: Measuring unit 4a: First reference light type laser Doppler measurement meter 4b: Second reference light type laser Doppler measurement meter 5: Driving motor 7: Optical disk 8a: First differential laser Doppler measurement meter 8b: Second differential laser Doppler measurement meter 10: Damping mechanism 21: Objective lens 22: Objective lens holder 23: Magnet stand 22c: First reflector 22d : Second reflector 23c: third reflector 23d: fourth reflector 24, 25: 45 degree mirror

Claims (3)

(57) [Claims] 1. An apparatus for measuring a movement characteristic of an optical disk based on a movement speed of an objective lens during rotation driving of the optical disk, comprising: an objective holding the objective lens and swingably disposed on a lower surface of the optical disk. A lens holder, a first reflector attached to one side surface of the objective lens holder, a second reflector attached to the back surface of the objective lens holder, and emitting a beam to the first reflector; A first reference light type laser Doppler measurement meter for detecting a moving speed of the objective lens holder in the tracking direction based on reflected light from one reflector, and emitting a beam to the second reflector, the second reflector A second reference light type laser Doppler measurement meter for detecting the movement speed of the objective lens holder in the focus direction based on the reflected light from the object, facing the second reflector And a 45-degree mirror that changes the direction of the beam emitted from the second reference-light type laser Doppler meter to 45 degrees and makes the beam enter the second reflector. The first reference-light type laser Doppler meter Calculating the movement speed of the objective lens based on the movement speed in the tracking direction of the objective lens holder detected in step (b) and the movement speed of the objective lens holder in the focus direction detected by the second reference light type laser Doppler meter. Motion measurement device for optical disks. 2. An apparatus for measuring a movement characteristic of an optical disk based on a movement speed of an objective lens during rotation driving of the optical disk, comprising: an objective holding the objective lens and swingably disposed on a lower surface of the optical disk. A lens holder; a first reflector attached to one side of the objective lens holder; a second reflector attached to the back of the objective lens holder; and a first reflector attached to one side of a support of the objective lens holder. A third reflector, a fourth reflector attached to the back side of the support, and emits a beam to the first and third reflectors, and to each reflected light from these first and third reflectors A first differential laser Doppler measurement meter for detecting a difference between a moving speed of the objective lens holder and the optical base in a tracking direction, and applying a beam to the second and fourth reflectors. The second differential laser Doppler measurement meter that emits and detects a difference in the movement speed of the objective lens holder and the optical base in the focusing direction based on each reflected light from the second and fourth reflectors, 45 ° which is located opposite to the second and fourth reflectors, and makes each beam emitted from the second differential type laser Doppler measurement meter change its direction by 45 ° and enter the second and fourth reflectors. comprising a mirror, movement speed of the first differential and the tracking direction of the movement speed of the objective lens holder which is detected by the laser Doppler meter, the focusing direction of the objective lens holder detected by said second differential laser Doppler meter A motion characteristic measuring device for an optical disk, wherein a motion speed of an objective lens is obtained based on the following. 3. A motion characteristic measuring apparatus of the optical disk according to claim 1 or 2, wherein the first reflector has a cross-shaped.