JPH02270138A - Optical recording and reproducing device - Google Patents

Abstract

PURPOSE:To securely prevent the occurrence of resonance by providing an internal force generating means, utilizing action force composing one part of this internal force or reaction force of the other part and driving a carriage part accordingly. CONSTITUTION:A seek coil 5 on the outside of a bobbin 3 is actuated by electromagnetic force by a permanent magnet 10 for seek adjustment while a focus adjustment movable part (b) is actuated by seek driving force fs, so that a seek control and a tracking control are performed. On the other hand, a focus coil 4 is actuated by electromagnetic force by a permanent magnet 30 for focus adjustment while the focus adjustment movable part (p) is actuated by focus driving force ff, so that a focus control is performed. Action force -(f) in the reverse direction of the seek driving force fs is generated on the seek coil 5 on the side of a lens holding body 2 while reaction force (f) against this action force -(f) is generated on the side of the carriage part (s). By this method, a resonance phenomenon at the time of the seek control and tracking control can securely be prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical recording and reproducing device that records and reproduces information, or records, reproduces, and erases information using an optical recording medium such as an optical disk. In particular, the present invention relates to improvements in optical recording and reproducing devices that can perform accurate tracking control.

[Prior Art] This type of optical recording/reproducing device uses a semiconductor laser (a>
, a collimator lens (b) that converts the diffused laser beam from this semiconductor laser (a) into parallel laser beam, and a beam shaping prism (C) that converts the spot shape of this laser beam from an elliptical shape to a substantially circular shape. , a beam splitter (e) that separates the incident laser beam that enters the optical recording medium (d) and the reflected laser beam that is reflected from the optical recording medium (d); and a linearly polarized beam that passes through the beam splitter (e). a 174-wavelength plate (f) that converts laser light into circularly polarized light;
an objective lens (g) which is movably provided and converges the laser beam that has passed through the 174 wavelength plate (f) onto a converging surface of the optical recording medium (d); and a reflected laser beam separated by the beam splitter (e). A device is known in which the main part thereof is composed of a cylindrical lens (j) that makes the signal incident on a four-part PIN photodiode (h) for obtaining a tracking error signal, a focus error signal, and a reproduction RF signal.

In this optical recording/reproducing device, in order to deal with eccentricity of the optical recording medium (d), as well as surface undulation and warping, the four-part PIN photodiode (h)
Performs tracking control and focus control of the optical head based on the tracking error signal and focus error signal obtained in For example, a drive system such as that described in Japanese Patent Laid-Open No. 63-50927 is incorporated.

That is, in this drive system, as shown in Figs. 7 and 8, a yoke (k) (k) is inserted into the cylindrical part, and a focus coil (fc) and a seek coil (SC) are wound around the outer peripheral surface. bobbin (m) (m) and this bobbin (m) (m)
A focus adjusting movable part (p) consisting of an objective lens (Q) attached to the holding member (n) via a holding member (n), and an optical recording medium (p) equipped with this focus adjusting movable part (p).
d) rails (Q) to (Q
), the carriage part (S) is movably provided on the top of the focus adjusting part (p) through bearings (r) to (r), and one end is fixed to the focus adjustment movable part (p) and the other end is fixed to the carriage part (S), and the focus adjustment movable part (p) is fixed to the carriage part (S), and the other end is fixed to the carriage part (S). A leaf spring (1) that supports the adjustable movable part (p) in a movable state substantially perpendicular to the surface of the optical recording medium (d).
The main part is composed of the leaf spring (1), and the electromagnetic force that acts on the seek coil (SC) when the seek coil (SC) is energized, that is, the seek driving force, is transferred to the leaf spring (1).
) to the carriage part (S), and the carriage part (
Seek control and tracking control are performed by moving S) along the radial direction of the optical recording medium (d), while the electromagnetic force acting on the focus coil (fc) is Focus control is performed by moving the focus adjusting movable part (p) in a direction substantially perpendicular to the surface of the optical recording medium (d) using force, that is, focus driving force.

Note that (U) and (U) in the figure are permanent magnets that form magnetic lines of force toward the seek coil (sc) and the focus coil (fc> side. This is a mechanical equivalent diagram of the drive system in the optical recording/reproducing device.
In the figure, (fS) represents the seek driving force acting on the focus adjustment movable part (p), and (f,) represents the seek drive force acting on the focus adjustment movable part (p).
) respectively show the focus driving force acting on them.

[Problems to be Solved by the Invention] By the way, as described above, the drive system in the conventional optical recording/reproducing device uses the plate spring ( 1) to the carriage part (S), and connects the focus adjustment movable part (p) and the carriage part (S) to the optical recording medium (d).
The seek coil (
When the frequency of the current flowing through the plate spring (SC) is made higher than a certain frequency value, that is, when tracking control is performed by finely vibrating the focus adjustment movable part (p) and the carriage part (S), the above plate spring (1 ) The electromagnetic force acting on the seek coil (SC) may no longer be transmitted to the carriage portion (S).

For this reason, the focus adjustment movable part (p) and the carriage part (S) do not move into one body, causing relative displacement, and resonance occurs, resulting in the problem that the tracking control cannot be performed accurately.

10 to 11 are graphs showing that resonance occurs at a certain frequency value (several 100s to several kHz), and FIG. 10 shows the focus adjustment movable part (1)) and carriage part (S ) is a graph showing the relationship between the amplitude and frequency in the focus direction of the focus adjustment movable part (p) when the focus adjustment movable part (p) and the carriage part (S) are vibrating. FIG. 4 is a graph diagram showing the relationship between the phase of the focus adjustment movable part (p) and the frequency when the focus adjustment movable part (p) is vibrating.

[i! [Means for Solving the Problems] The present invention has been made in view of the above-mentioned problems.The object of the present invention is to provide an optical system that can perform accurate tracking control regardless of the frequency value of the current flowing through the seek coil. The purpose of the present invention is to provide a recording and reproducing device that can be used for recording and reproducing data.

In other words, the present invention includes an objective lens that is placed near an optical recording medium and that converges the focused light from a light source onto a converging surface of the optical recording medium, and an objective lens that is arranged approximately perpendicular to the surface of the optical recording medium by the electromagnetic force accompanying the energization of the objective lens. A focus coil that drives in the direction,
The main parts of the objective lens include a seek coil that is driven in the radial direction of the optical recording medium by electromagnetic force when the objective lens is energized, and a coil support section that supports the focus coil and the seek coil. A focus adjustment movable part in which a focus coil, a seek coil, and a coil support part are integrally fixed; a carriage part mounted with this focus adjustment movable part and provided so as to be movable in the radial direction of an optical recording medium; an optical recording/reproducing device comprising: a plate spring having a focus adjustment movable part and the other end fixed to the carriage part, and supporting the focus adjustment movable part in a movable state in a direction substantially perpendicular to the surface of the optical recording medium. Based on this premise, an internal force generating means is provided between the carriage part and the focus adjustment movable part to generate an acting force and a reaction force in opposite directions in the radial direction of the optical recording medium on the carriage part and the focus adjustment movable part. It is characterized by this.

In such a technical means, the internal force generating means provided between the carriage part and the focus adjustment movable part is configured such that an acting force forming part of the internal force acts on the carriage part and a reaction force thereof acts on the focus adjustment movable part. However, it is also possible to have an arbitrary configuration in which a reaction force acts on the carriage section and the force acts on the focus adjustment movable section, or vice versa.

The coil support section is composed of a lens holder that holds the objective lens and has a focus coil wound around its outer circumferential surface, and a bobbin that is attached to the outer periphery of the lens holder and has a seek coil wound around it. In this case, the internal force generating means may include, for example, a focus adjustment magnet provided in the cylindrical portion of the bobbin, both ends of which are attached to the carriage portion, and forming lines of magnetic force directed toward the focus coil, and a focus adjustment magnet wound around the bobbin. This can be configured with a rotated seek coil. In this configuration, an acting force acts on the focus adjustment movable section having the seek coil, and a reaction force acts on the carriage section.

Here, resonance can be prevented when this internal force (f), that is, the value of the acting force or its reaction force, satisfies the following requirements.

In other words, when determining the requirements using the mechanical equivalent diagram in Fig. 3, the mass of the focus adjustment movable part (p) is m1 the mass of the carriage part (S) is M1 the spring constant of the leaf spring (1) in the theta direction. When the seek driving force is f3, the above internal force is f, and the displacement of the focus adjustment movable part (1) in the theta direction is x1, the displacement of the carriage part (S) in the theta direction is y. The equation of motion of the focus adjustment movable part (p) and the carriage part (S>) is as follows.

m(d x/dt2)+K(x-y)-f-fM
(dV/dt2)+K(y-x)-f This is converted to Laplace to obtain the transfer function of the displacement of the focus adjustment movable part (p) with respect to the seek driving force, as follows.

However, X, F, and F are X1f, f17) each S , where S is a Laplace variable.

X(S)/FS (S)- [(mMs + (m+M)K) +M" 52-M
(m+M) S2 , the above-mentioned transfer function becomes X (S)/F, (S)-1/ (m+M)S, and the spring constant K is no longer related to this function, so that the above-mentioned resonance no longer occurs.

Therefore, by appropriately adjusting the number of turns of the seek coil wound around the bobbin, the magnetic strength of the focus adjustment magnet, and the seek adjustment magnet, and setting it so that f-f, -M/(m+M), the above-mentioned result can be achieved. It becomes possible to reliably prevent resonance.

[Operation] According to the above-mentioned technical means, an internal force generating means is provided in the carriage part and the focus adjustment movable part without using the seek driving force acting on the seek coil of the focus adjustment movable part, and this internal force is generated. In order to drive the carriage part using the action force of one or the reaction force of the other,
It is possible to reliably prevent resonance from occurring regardless of the frequency value of the current flowing through the seek coil.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.
As shown in Figures to Figure 2, there is a focus adjustment movable section (p), a carriage section (S) on which the focus adjustment movable section (p) is mounted, and this carriage section (S) and the focus adjustment movable section [)). The main part thereof is a leaf spring (1) that connects the two.

First, the focus adjustment movable part (p) is connected to the objective lens (
1), a cylindrical lens holder (2) with a substantially rectangular cross section that holds this objective lens (1), and this lens holder (2).
a pair of bobbins (3) attached to the outer circumference of the lens holder (2), a focus coil (4) wound around the outer circumference of the lens holder (2), and a focus coil (4) wound around the outer circumference of the bobbin (3). It is composed of a seek coil (5) and these are integrally fixed. In addition, the lens holder (2)
has a cylindrical inner housing (21) into which the objective lens (1) is fitted in the upper part and whose inner diameter at the center part is smaller than the other parts, and a cylindrical inner housing (21) which is disposed on the outside through a connecting plate (6) and whose outer periphery is It consists of a cylindrical outer housing (22) with a focusing coil (4) wound around its surface, and a carriage of the carriage part (S) is disposed between these inner and outer housings (21) and (22). A gap (8) is formed in which a part of the main body (7) is inserted. Also,
A pair of rails (9) (9) disposed along the radial direction of an optical recording medium (not shown) are inserted into the cylindrical portion of the bobbin (3), and are provided on the outside of the bobbin (3). is the seek coil (5) wound around the outer circumferential surface of this bobbin (3).
(5) The permanent magnet (10) for seek adjustment that forms lines of magnetic force toward the side (10) has its N pole facing the bobbin (3) side along the length direction of the rails (9) (9). It is arranged.

On the other hand, the carriage part (S) has a carriage main body (7).
) and a pair of permanent magnets (30) for focus adjustment attached to this carriage body (7), and the approximate center of the carriage body (7) is a cylindrical part (31). A cylindrical portion (31) is interposed between the inner side of the lens holder (2) and the gap (8) between the outer housings (21) and (22), and the inner wall of the cylindrical portion (31) and the inner housing (21) It is in sliding surface contact with the outer wall. Further, the permanent magnet (30) for focus adjustment is disposed within the cylindrical portion of the bobbin (3) with its N pole facing the focus coil (4) side, and both ends thereof are connected to the carriage body. (7) is attached. Furthermore,
Bearings (32) to (32) are attached to the upper and lower ends of the carriage body (7), and these bearings (32) to (32) are connected to the rails (9) and (9).
) so that the carriage part (S) moves along the radial direction of the optical recording medium.

The leaf spring (1) is made of a spiral metal material, and its inner side is attached to the lens holder (2) of the focus adjustment movable part (p), and its outer side is attached to the carriage body (2) of the carriage section (S). 7), and by the action of this leaf spring (1), the focus adjustment movable part (p)
can be moved up and down.

In the optical recording/reproducing device configured in this way,
Focused light from a light source (not shown) provided on the main body of the apparatus is incident on an objective lens (1) via a reflecting prism (not shown), and the objective lens (1) directs the focused light to an optical recording medium ( (not shown) to record information,
It is something that can be reproduced, erased, etc.

In this optical recording/reproducing device, when the seek coil (5) is energized via a lead wire (not shown),
An electromagnetic force from a permanent magnet (10) for seek adjustment acts on the outer seek wheel (5) of the bobbin (3), and as shown in the mechanical equivalent diagram of FIG.
The seek driving force (f, ) acts on the focus coil () to perform seek control and tracking control, while the focus coil (
4), an electromagnetic force from a permanent magnet (30) for focus adjustment acts on this focus coil (4), and as shown in the mechanical equivalent diagram of Fig. 3, the focus adjustment movable part (p) is focused. Focus control is performed by applying a driving force (f,).

Here, during seek control and tracking control, the electromagnetic force by the permanent magnet (30) for focus adjustment also acts on the seek coil (5) on the inside of the bobbin (3), that is, on the lens holder (2) side. , and since the direction of the current flowing through the seek coil (5) in this part is opposite to that of the outer seek coil (5), the seek coil (5) in this part
5), an acting force (-f) opposite to the seek driving force (f) is generated, and since this acting force (-f) is an internal force, this acting force is not applied to the carriage part (S) side. (-f)
A reaction force (f) will be generated.

In this optical recording/reproducing device, a permanent magnet (10) is used for adjusting the number of turns of the seek coil (5) wound around the bobbin (3) and for seek adjustment, as well as for focus adjustment.
(30) by adjusting the magnetic force strength appropriately, f=f −M
/(m+M), (where m is the mass of the huff focus adjustment movable part, M is the mass of the carriage part), so the above acting force (-f) and reaction force (f) By this action, it is possible to reliably prevent resonance phenomena during seek control and tracking control.

Therefore, regardless of the frequency value of the current flowing through the seek coil (5), the focus adjustment movable part (p) and the carriage part (
Since it is possible to always move and operate S) in an integrated manner, it has the advantage that tracking control can be performed accurately.

FIG. 4 is a graph showing the relationship between the amplitude and frequency of the focus adjustment movable part (p) in the theta direction when the focus adjustment movable part (p) and the carriage part (S) are vibrating. 5 is a graph showing the relationship between the phase of the focus adjustment movable part (p) and the frequency when the focus adjustment movable part (p) and the carriage part (S) are vibrating. From these graphs, it can be confirmed that no resonance phenomenon occurs.

[Effects of the Invention] As described above, the present invention provides an internal force generating means in the carriage part and the focus adjustment movable part without using the seek driving force acting on the seek coil of the focus adjustment movable part, and generates one of the internal forces. Since the carriage section is driven using the acting force or the reaction force of the other component, it is possible to reliably prevent resonance from occurring regardless of the frequency value of the current flowing through the seek coil.

Therefore, it is possible to always move the focus adjustment movable section and the carriage section in an integrated manner, which has the effect of accurately performing tracking control.

[Brief explanation of drawings]

1 to 5 show an embodiment of the present invention, and FIG. 1 is a partially cutaway perspective view of an optical recording/reproducing apparatus according to the embodiment;
Figure 2 is a sectional view taken along the line 1 in Figure 1, Figure 3 is a mechanical equivalent diagram of this device, and Figure 4 is the relationship between the amplitude and frequency in the theta direction of the focus adjustment movable part (p) in this device. A graph showing the focus adjustment movable part (0) in Figure 5.
FIG. 6 is a graph showing the relationship between the phase in the theta direction and frequency, and FIGS. 6 to 11 show conventional examples;
The figure is a schematic diagram of the configuration of an optical recording and reproducing device, FIG. 7 is a plan view of the optical recording and reproducing device with a built-in drive system, FIG. 8 is a sectional view taken along the line ■-■ of FIG. A mechanical equivalent diagram of this device, FIG. 10 is a graph showing the relationship between the amplitude and frequency in the theta direction of the focus adjustment movable portion (p) in this device, and FIG. 11 is a graph of the focus adjustment movable portion (p) in this device. FIG. 2 is a graph diagram showing the relationship between the phase in the theta direction and frequency. [Description of symbols] (1)... Objective lens (2)... Lens holder (3)... Bobbin (4)... Focus coil (5)... Seek coil (10)... Permanent magnet for seek adjustment (30)...
Permanent magnet for focus adjustment (p)... Focus adjustment movable part (S)... Carriage part (1)... Leaf spring patent Applicant: Fujishichi Rox Co., Ltd. Representative: Satoshi Nakamura, patent attorney Hiro (2 others) Fig. 2 Fig. 3 f+ Fig. 4 0KHz Frequency Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 1 hand Fig. 11

Claims (2)

[Claims] (1) An objective lens that is placed near the optical recording medium and converges the focused light from the light source onto the convergence surface of the optical recording medium, and the objective lens is arranged in a direction approximately perpendicular to the surface of the optical recording medium due to the electromagnetic force that occurs when electricity is applied to the objective lens. The main parts thereof include a focus coil to be driven, a seek coil to be driven in the radial direction of the optical recording medium by electromagnetic force caused by energization of the objective lens, and a coil support part to support the focus coil and the seek coil. , a focus adjustment movable part in which these objective lenses, focus coils, seek coils, and coil support parts are integrally fixed, and a focus adjustment movable part that is mounted so as to be movable in the radial direction of the optical recording medium. and a plate spring having one end fixed to the focus adjustment movable part and the other end fixed to the carriage part, supporting the focus adjustment movable part in a movable state in a direction substantially perpendicular to the surface of the optical recording medium. In the optical recording/reproducing device, an internal force is generated between the carriage part and the focus adjustment movable part to generate an action force and a reaction force in opposite directions in the radial direction of the optical recording medium on the carriage part and the focus adjustment movable part. An optical recording/reproducing device characterized by being provided with means. (2) a lens holder in which the coil support part holds an objective lens and a focus coil is wound around the outer peripheral surface of the lens holder;
a bobbin attached to the outer circumferential surface of the lens holder and around which a seek coil is wound; and the internal force generating means is provided in a cylindrical portion of the bobbin, both ends of which are attached to the carriage portion. 2. The optical recording and reproducing apparatus according to claim 1, comprising a focus adjustment magnet that forms lines of magnetic force directed toward the focus coil, and a seek coil wound around the bobbin.