JPH0648539B2 - Optical recording / reproducing device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an optical recording / reproducing apparatus for recording / reproducing information or recording / reproducing / erasing information by using an optical recording medium such as an optical disk, and more particularly, to an optical recording / reproducing apparatus. The present invention relates to an improvement of an optical recording / reproducing device capable of performing accurate tracking control.

[Prior Art] As an optical recording / reproducing apparatus of this type, as shown in the schematic configuration diagram of FIG.
A collimator lens (b) for converting the diffused laser light from the semiconductor laser (a) into parallel laser light; and a beam shaping prism (c) for converting the spot shape of the laser light from an elliptical shape to a substantially circular shape. , A beam splitter (e) for separating incident laser light incident on the optical recording medium (d) and reflected laser light reflected from the optical recording medium (d)
And a quarter-wave plate (f) that passes the beam splitter (e) and converts the linearly polarized laser light into circularly polarized light,
An objective lens (g) that is movably provided to converge the laser light that has passed through the quarter-wave plate (f) onto the converging surface of the optical recording medium (d), and reflection separated by the beam splitter (e). There is known a device that constitutes a main part of a cylindrical lens (j) that causes a laser beam to enter a four-division PIN photodiode (h) for obtaining a tracking error signal, a focus error signal, and a reproduction RF signal.

Then, in this optical recording / reproducing apparatus, in order to deal with the eccentricity of the optical recording medium (d) and the waviness and warpage of the surface, the tracking error signal obtained by the four-division PIN photodiode (h) is obtained. It is necessary to perform tracking control or focus control of the optical head on the basis of a focus error signal or seek control for moving the optical head from one track to another track for reading recorded information. A drive system as described in JP-A-63-50927 is incorporated.

That is, in this drive system, as shown in FIGS. 9 to 10, the yokes (k) (k) are inserted into the cylindrical portion thereof, and the focus coil (fc) and the seek coil (sc) are wound around the outer peripheral surface. A focus adjustment movable part (p) including a bobbin (m) (m) and an objective lens (g) attached to the bobbin (m) (m) via holding members (n) (n), An optical recording medium (d) equipped with this focus adjustment movable part (p)
A carriage part (s) movably provided on rails (q) to (q) arranged along the radial direction of the bearings via bearings (r) to (r), and one end of the focus adjustment movable part ( p) and the leaf spring (t) which has the other end fixed to the carriage portion (s) and supports the focus adjustment movable portion (p) in a state of being movable in a direction substantially perpendicular to the optical recording medium (d) surface. The main part is composed of the seek coil (s
The electromagnetic force acting on the seek coil (sc) upon energization of c), that is, the seek driving force is transmitted to the carriage section (s) via the leaf spring (t), and the carriage section (s) is transmitted to the optical recording medium. While performing seek control and tracking control by moving along the radial direction of (d), the electromagnetic force that acts on the focus coil (fc) as the focus coil (fc) is energized, that is, the focus driving force. The focus control is performed by moving the focus adjustment movable part (p) in a direction substantially perpendicular to the surface of the optical recording medium (d).

In the figure, (u) and (u) are permanent magnets that form magnetic lines of force toward the seek coil (sc) and the focus coil (fc). Further, FIG. 11 seeks acting mechanical equivalent diagram of a driving system in an optical recording and reproducing apparatus shown in FIG. 9-FIG. 10, in FIG. (F _s) is the focus adjusting movable portion (p) The driving force, (f _f ) shows the focus driving force acting on the focus adjustment movable part (p).

[Problems to be Solved by the Invention] In the meantime, as described above, the drive system in the conventional optical recording / reproducing apparatus applies the electromagnetic force acting on the seek coil (sc) of the focus adjustment movable portion (p). It is transmitted to the carriage section (s) via a spring (t), and the focus adjustment movable section (p) and the carriage section (s) are transferred to the optical recording medium (d).
Since the seek control and the tracking control are performed by integrally moving along the radial direction of, the frequency of the current flowing in the seek coil (sc) is set higher than a certain frequency value, that is, the focus adjustment movable unit. When tracking control is performed by finely vibrating (p) and the carriage section (s), the electromagnetic force acting on the seek coil (sc) is transmitted to the carriage section (s) via the leaf spring (t). Sometimes it wasn't done.

For this reason, there is a problem that the focus adjustment movable part (p) and the carriage part (s) do not move integrally and a relative displacement occurs, and resonance occurs and the tracking control cannot be performed accurately.

It should be noted that FIGS. 12 to 13 show a certain frequency value (several 100 to several kH).
FIG. 12 is a graph showing that resonance occurs in Z), and FIG. 12 shows 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. 13 is a graph showing the relationship between the amplitude and the frequency of the focus adjustment movable part (p) and the frequency of the focus adjustment movable part (p) when the focus adjustment movable part (p) and the carriage part (s) are vibrating. It is a graph showing the relationship with.

Focusing on such a problem, the present inventor focuses an acting force and a reaction force, which are opposite to each other in the radial direction of the optical recording medium, between the focus adjustment movable part (p) and the carriage part (s). By arranging an internal force generating means for generating in the adjustable movable part (p) and the carriage part (s), the carriage part (s) is driven by utilizing an action force or a reaction force that constitutes one of the internal forces. An invention (Japanese Patent Application No. 1-90838) relating to an optical recording / reproducing apparatus capable of preventing the occurrence of the resonance has already been proposed.

[Means for Solving the Problems] The present invention is a further improvement of the invention according to Japanese Patent Application No. 1-90838 mentioned above. The object of the present invention is to provide accurate measurement regardless of the frequency value of the current flowing through the seek coil. An object of the present invention is to provide an optical recording / reproducing device capable of reliably performing accurate tracking control.

That is, according to the present invention, an objective lens which is arranged in the vicinity of the optical recording medium and converges the converged light from the light source to the converging surface of the optical recording medium, and an electromagnetic force generated when the objective lens is energized makes the surface of the optical recording medium substantially vertical. A focus coil that drives in the direction
A seek coil that drives the objective lens in the radial direction of the optical recording medium by an electromagnetic force accompanying energization, and a coil support portion that supports the focus coil and the seek coil, a main part thereof is configured. A focus adjustment movable unit in which a focus coil, a seek coil, and a coil support unit are integrally fixed, a carriage unit mounted with the focus adjustment movable unit and movable in the radial direction of the optical recording medium, And a leaf spring having the other end fixed to the carriage unit and the other end fixed to the carriage unit so as to support the focus adjustment movable unit in a direction substantially perpendicular to the surface of the optical recording medium. As a precondition, a carrier force and a reaction force in opposite directions in the radial direction of the optical recording medium are carried between the carriage section and the focus adjustment movable section. And a magnetic fluid filling the gap between the carriage section and the focus adjustment movable section, and the coil support section holds the objective lens and holds the outer circumference of the coil support section. A lens holding body having a focus coil wound on its surface, and a bobbin attached to the outer peripheral surface of the lens holding body and having a seek coil wound thereon, and the internal force generating means are provided in the cylindrical portion of the bobbin. The focus adjustment magnet is provided on both ends of the bobbin and is attached to the carriage portion to form a magnetic force line toward the focus coil side, and a seek coil wound around the bobbin. The focus adjustment is performed when the seek coil is energized. The acting force and reaction force are generated by causing the electromagnetic force generated by the application magnet to act on the seek coil portion on the lens holder side as well. It is characterized in that there was Unishi.

In the internal force generating means by such technical means,
The acting force acts on the side of the focus adjustment movable unit having the seek coil, and the reaction force acts on the carriage unit.

Here, this internal force (f), that is, the value of the acting force or its reaction force, can prevent resonance when the following requirements are met.

That is, when the requirements are determined using the mechanical equivalent diagram of FIG. 5, the mass of the focus adjustment movable part (p) is m, the mass of the carriage part (s) is M, and the leaf spring (t) is in the seek direction. The spring constant is K, the seek driving force is f _s , the internal force is f, the displacement of the focus adjustment movable part (p) in the seek direction is x, and the displacement of the carriage part (s) in the seek direction is y. In this case, the equations of motion of the focus adjustment movable part (p) and the carriage part (s) are as follows. m
^{(D 2 × / dt 2)} + K (x-y) = f s -f M (d 2 × / dt 2) + K (y-x) = f which was Laplace transform focus adjusting movable portion with respect to a seek drive force The transfer function of the displacement of (p) is calculated as follows.

However, X, _{F s,} and _F, x, _f s, represents the Laplace transform of each f, S is the Laplace variable.

^{_{X (S) / F s (}} S) = [{mMs 2 + (m + M) K} + M 2 S 2 -M (m + M) S 2 × F / F s] × 1 / {mMS 2 + (m + M) K} × 1 / (m + M) S ² where F (m + M) = F _s · M, that is, when f = fs _{_M} / (m + M) is set, the transfer function is X (S) / F _s (S ) = 1 / (m + M) S ² and the spring constant K does not relate to this function, so that the above resonance does not occur.

Accordingly, the by setting as to adjust the number of turns or focusing magnets seek coil wound on the bobbin, the magnetic strength of the seek adjustment magnet appropriate, the _{f = f s · M / (} m + M) Resonance can be surely prevented.

On the other hand, the magnetic fluid interposed between the carriage section and the focus adjustment movable section fills the gap between the carriage section and the focus adjustment movable section to more reliably prevent the resonance.

That is, when an optical recording / reproducing apparatus is constructed by assembling the carriage unit and the focus adjustment movable unit, the carriage unit and the focus unit are restricted due to restrictions on the shapes of the respective carriage units and the focus adjustment movable unit, as well as processing accuracy. A non-uniform gap may occur between the adjustment movable parts, and even if the internal force generating means is provided between the carriage part and the focus adjustment movable part, resonance may occur due to the non-uniform gap described above. The magnetic fluid absorbs minute vibrations of the carriage unit and the focus adjustment movable unit due to the resonance, integrates the carriage unit and the focus adjustment movable unit, and reliably prevents the resonance.

The magnetic fluid includes a solvent such as ester hydrocarbon, oil, fluorocarbon oil, and water, and a magnetic material such as a ferromagnetic oxide or a ferromagnetic metal dispersed in the solvent by using a surfactant. The main part of the colloidal liquid is, for example, "Marpo Magna" (trade name, manufactured by Matsumoto Yushi-Seiyaku Co., Ltd.). As a means for holding the magnetic fluid, a method of holding it by a permanent magnet or the like attached to the carriage portion or the focus adjustment movable portion can be used.

[Operation] According to the technical means as described above, the internal force generating means is provided between the carriage portion and the focus adjustment movable portion, and one of the internal forces is exerted without utilizing the seek driving force acting on the seek coil of the focus adjustment movable portion. Since the carriage portion is driven by using the acting force that constitutes the above or the other reaction force, it becomes possible to prevent the occurrence of resonance regardless of the frequency value of the current flowing through the seek coil, and The magnetic fluid interposed between the focus adjustment movable parts absorbs minute vibrations of the carriage part and the focus adjustment movable part to integrate the carriage part and the focus adjustment movable part, so that the above-mentioned resonance is more reliably generated. Can be prevented.

[Embodiment] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. An optical recording / reproducing apparatus according to this embodiment will be described as a first embodiment.
As shown in FIGS. 2 and 3, the focus adjustment movable part (p)
A carriage section (s) carrying the focus adjustment movable section (p), a leaf spring (t) connecting the carriage section (s) and the focus adjustment movable section (p), and a carriage section (s). And the magnetic fluid (Lq) interposed in the gap between the focus adjustment movable part (p) constitutes the main part.

First, the focus adjustment movable part (p) includes an objective lens (1), a lens holder (2) that holds the objective lens (1) and has a substantially rectangular cross section, and a lens holder (2). ) A pair of bobbins (3) attached to the outer peripheral surface of
The focus coil (4) is wound around the outer peripheral surface of the lens holder (2), and the seek coil (5) is wound around the outer peripheral surface of the bobbin (3). It is fixed to. Further, the lens holder (2) is fitted with the objective lens (1) at an upper portion thereof, and has a cylindrical inner housing (21) having an inner diameter of a central portion smaller than other portions, and a connecting plate (21) on the outer side thereof. 6) A cylindrical outer housing (22) which is disposed via (6) and has a focus coil (4) wound around its outer peripheral surface. These inner and outer housings (21) ( A gap portion (8) in which a part of the carriage body (7) of the carriage portion (s) is interposed is formed between the portions 22). In addition, a pair of rails (9) arranged along the radial direction of an optical recording medium (not shown) in the cylindrical portion of the bobbin (3).
(9) is inserted, and seek on the outside of the bobbin (3) forms magnetic lines of force toward the seek coil (5) (5) side wound around the outer peripheral surface of the bobbin (3). Adjusting permanent magnets (10) (10) bobbin (3) with its N pole
It is arranged along the length direction of the rails (9) (9) facing the side.

On the other hand, the carriage part (s) is composed of a carriage body (7) whose upper and lower surfaces are substantially open in the center, and a pair of permanent magnets (30) for focus adjustment attached to the carriage body (7). A substantially central portion of the carriage body (7) is a tubular portion (31), and the tubular portion (31) is located inside and outside the lens holder (2).
1) It is inserted in the gap (8) of (22), and this cylinder (31)
And the outer wall of the inner housing (21) are in slidable surface contact with each other. The focus adjusting permanent magnet (30) is arranged in the tubular portion of the bobbin (3) with its N pole facing the focus coil (4) side, and
Both ends thereof are attached to the carriage body (7). Further, bearings (32) to (32) are attached to the upper and lower ends of the carriage body (7) at four positions, and these bearings (32) to (32) are attached to the rail (9).
The carriage portion (s) is adapted to move in the radial direction of the optical recording medium by engaging with (9).

Next, the leaf spring (t) is made of a spiral metal material, the inside of which is the lens holder (2) in the focus adjustment movable part (p), and the outside of which is the carriage part (s).
It is fixedly attached to the upper and lower open portions of the carriage body (7), and the focus adjustment movable portion (p) can be moved in the vertical direction by the action of the leaf spring (t).

Further, in the upper and lower open portions of the carriage body (7), a substantially ring-shaped permanent magnet group (7) as shown in FIGS.
0) to (70) are fitted and arranged, and the magnetic fluid (Lq) is held by being attracted by these permanent magnet groups (70) to (70). That is, the permanent magnet group (70) to
(70) are assembled in a ring shape with their opposite poles adjacent to each other. These magnetic fluids (Lq) are formed along the lines of magnetic force (71) formed between these permanent magnets (70)-(70). ) Is held (see FIG. 4) and the gap between the lens holding portion (2) and the carriage body (7) is filled. As the magnetic fluid (Lq), "Marpo Magna" manufactured by Matsumoto Yushi-Seiyaku Co., Ltd. is used.

In the optical recording / reproducing apparatus configured as described above,
Focused light from a light source (not shown) provided on the apparatus main body side is incident on an objective lens (1) via a reflection prism (not shown), and the focused light is converted into an optical recording medium by the objective lens (1). Recording of information converged on the convergence surface (not shown),
It is reproduced and erased.

In this optical recording / reproducing apparatus, when the seek coil (5) is energized via a lead wire (not shown),
The seek coil (5) outside the bobbin (3) is acted on by the electromagnetic force of the seek adjusting permanent magnet (10) to move the focus adjusting movable part (p) as shown in the mechanical equivalent diagram of FIG.
Seek control and tracking control are performed by the seek driving force (f _s ) acting on the target coil. On the other hand, when the focus coil (4) is energized, the focus coil (4) receives an electromagnetic field generated by a permanent magnet (30) for focus adjustment. The force acts, and as shown in the mechanical equivalent diagram of FIG. 5, the focus drive force (f _f ) acts on the focus adjustment movable part (p) to perform focus control.

Here, during seek control or tracking control, the electromagnetic force generated by the focus adjusting permanent magnet (30) acts on the inside of the bobbin (3), that is, the seek coil (5) on the side of the lens holder (2). and, the opposite direction of the current flowing through the seek coil of the site (5) for opposite the outer seek coil (5), the seek driving force to seek coil of the site (5) and (f _s) A direction acting force (-f) is generated, and since this acting force (-f) is an internal force, this acting force (-f) is present on the carriage section (s) side.
A reaction force (f) with respect to is generated.

In this optical recording / reproducing apparatus, the number of turns of the seek coil (5) wound around the bobbin (3) and seek adjustment, and focus adjustment permanent magnet (10).
Adjust the magnetic field strength of (30) appropriately and f = f _s · M / (m
+ M), (where m is the mass of the focus adjustment movable part, M
Represents the mass of the carriage section), and the acting force (-) directly acting on the carriage section (s) without utilizing the seek driving force acting on the seek coil (5). Since the carriage portion (s) is driven by using f) or the reaction force (f), it is possible to prevent the resonance phenomenon during seek control or tracking control.

Further, the lens holding portion (2) and the carriage body (7)
A magnetic fluid (Lq) that fills this gap is interposed between the lens holding portion (2) and the carriage body (7) by absorbing minute vibrations of the lens holding portion (2) and the carriage body (7). Since the and are integrated, the above resonance phenomenon can be prevented more reliably.

Therefore, the focus adjustment movable part (p) and the carriage part (s) can always be integrally moved regardless of the frequency value of the current flowing through the seek coil (5), and accurate tracking control can be performed. It has the advantage that

Incidentally, FIG. 6 is a graph showing the relationship between the amplitude and frequency in the seek direction of the focus adjustment movable part (p) when the focus adjustment movable part (p) and the carriage part (s) are vibrating. FIG. 7 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 the resonance phenomenon has not occurred.

[Effect of the Invention] As described above, the present invention provides the internal force generating means between the carriage part and the focus adjustment movable part, and uses one of the internal forces without using the seek driving force acting on the seek coil of the focus adjustment movable part. Since the carriage portion is driven by using the acting force or the other reaction force that constitutes it, it becomes possible to prevent the occurrence of resonance regardless of the frequency value of the current flowing through the seek coil, and the carriage portion and the focus portion can be prevented. Since the magnetic fluid interposed between the adjustment movable parts absorbs these minute vibrations of the carriage part and the focus adjustment movable part to integrate the carriage part and the focus adjustment movable part, the above-mentioned resonance is more reliably generated. It becomes possible to prevent it.

Therefore, the carriage unit and the focus adjustment movable unit can always be integrally moved, so that accurate tracking control can be reliably performed.

[Brief description of drawings]

1 to 7 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.
2 is a sectional view taken along the line II-II of FIG. 1, FIG. 3 is a perspective view of a permanent magnet group holding a magnetic fluid, FIG. 4 is its plan view, and FIG. 5 is a mechanical equivalent view of this device. FIG. 6 is a graph showing the relationship between the amplitude and frequency of the focus adjustment movable part (p) in the seek direction in this apparatus, and FIG. 7 is the phase and frequency of the focus adjustment movable part (p) in the seek direction. FIG. 8 to FIG. 13 show a conventional example, FIG. 8 is a schematic configuration diagram of an optical recording / reproducing apparatus, and FIG. 9 is a drive system incorporated. FIG. 10 is a plan view of the optical recording / reproducing apparatus, FIG. 10 is a sectional view taken along line XX in FIG. 9, FIG. 11 is a mechanical equivalent view of this apparatus, and FIG. 12 is a focus adjustment movable part (p) in this apparatus. ) Is a graph showing the relationship between the amplitude and frequency in the seek direction, and Fig. 13 is the seek method of the focus adjustment movable part (p). Of a graph chart showing the relationship between phase and frequency. [Explanation of symbols] (1) …… Objective lens (2) …… Lens holder (3) …… Bobbin (4) …… Focus coil (5) …… Seek coil (10) …… Seek adjustment permanent magnet (30) …… Permanent magnet for focus adjustment (70) …… Permanent magnet holding magnetic fluid (p) …… Focus adjustment movable part (s) …… Carriage part (t) …… Leaf spring (Lq)… … Magnetic fluid

Claims (1)

[Claims] 1. An objective lens arranged near an optical recording medium for converging focused light from a light source to a converging surface of the optical recording medium,
A focus coil for driving the objective lens in a direction substantially perpendicular to the surface of the optical recording medium by an electromagnetic force accompanying energization; a seek coil for driving the objective lens in a radial direction of the optical recording medium by an electromagnetic force accompanying energization; A main part is composed of a coil support part that supports the focus coil and the seek coil, and an objective lens, a focus coil, a seek coil, and a focus adjustment movable part in which the coil support part is integrally fixed, A carriage part which is provided with the focus adjustment movable part and is movable in the radial direction of the optical recording medium, and one end is fixed to the focus adjustment movable part and the other end is fixed to the carriage part, and the focus adjustment movable part is optically recorded. An optical recording / reproducing apparatus, comprising: a leaf spring supported in a state of being movable in a direction substantially perpendicular to the medium surface. Section and the focus adjustment movable section, internal force generating means for generating an acting force and a reaction force in the radial direction of the optical recording medium, which are in opposite directions to each other in the carriage section and the focus adjustment movable section, and these carriage section and the focus adjustment movable section. And a magnetic fluid that fills the gap between the parts, and a lens holder that holds the objective lens and the focus coil is wound around the outer peripheral surface of the coil support part,
A bobbin mounted on the outer peripheral surface of the lens holder and wound with a seek coil. The internal force generating means is provided in the cylindrical portion of the bobbin, and both ends thereof are attached to the carriage portion and the focus is adjusted. A focus adjustment magnet that forms magnetic lines of force toward the coil side,
The seek coil is wound around the bobbin, and when the seek coil is energized, the electromagnetic force of the focus adjusting magnet is also applied to the seek coil portion on the lens holder side to generate the acting force and the reaction force. An optical recording / reproducing apparatus characterized by the above.