JP3506026B2 - Optical recording / reproducing 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 recording / reproducing apparatus capable of optically recording / reproducing or erasing information by projecting a light spot on an optical recording / reproducing medium.

[0002]

2. Description of the Related Art In recent years, an apparatus (hereinafter referred to as an optical disk apparatus) for recording and reproducing information using a disc-shaped optical recording / reproducing medium (hereinafter referred to as a disk) has advantages of large capacity and high speed. Widely used for voice, image and data recording. Recent optical disk devices include, for example, CDs and CD-ROMs (Read Only Memories).
y), not only reproduction or recording of a CD-R (Rewritable) but also DVD (Digital Vers)
Recording / reproducing of discs having different track pitches such as an atile disc) has become possible with one optical disc device. Since characteristics such as substrate thickness and recording density are different between the CD and the DVD, the optical recording / reproducing apparatus mounted in the optical disk apparatus has an objective lens and a wavelength having different focal lengths and numerical apertures (NA) corresponding to the respective disks. A method is often used in which different laser light sources and optical components are mounted and a dedicated optical system is selected and used according to the characteristics of the disc.

Conventionally, as an optical recording / reproducing apparatus for switching and selecting an objective lens corresponding to a disc of a different type, those described in JP-A-8-138265 and JP-A-8-221779 are known.

Hereinafter, FIG. 10, FIG. 11, FIG. 12 and FIG.
The conventional optical recording / reproducing apparatus of the objective lens switching type will be described with reference to FIG.

FIG. 10 is a plan view of an optical recording / reproducing apparatus having a conventional objective lens switching mechanism, and FIG. 11 is a diagram showing the shape of a tracking coil mounted in the conventional optical recording / reproducing apparatus.
FIG. 12 is a diagram showing a waveform of a current passed through a tracking coil for switching an objective lens in a conventional optical recording / reproducing apparatus, and FIG. 13 is a plan view showing another example of an optical recording / reproducing apparatus having a conventional objective lens switching mechanism. Is.

In FIG. 10, a lens holding member 402 has objective lenses 407a and 407b corresponding to disks having different substrate thicknesses and recording densities, and a tracking coil 41.
4a, 414b, 414c, 414d, 414e, 41
4f is bonded and fixed to form a mover, which is capable of rotating around the rotating shaft 415 and sliding in the axial direction. The mover rotates and the tracking coils 414a, 4
14b, 414c, 414d, 414e, and 414f at positions facing the permanent magnets 412a, 413a, and 412.
b and 413b are installed to form a magnetic circuit. The lens holding member 402 has a tracking coil 414a.
And 414b, between 414b and 414c, between 414d and 414e, and between 414e and 414f, respectively, the magnetic material pieces 419a, 419b, 419c, 419d.
Embedded therein, and permanent magnets 412a, 413a and 4
The magnetic attraction force generated between the moving elements 12b and 413b positions the mover in the rotational direction and the sliding direction.

Next, the operation of the conventional optical recording / reproducing apparatus thus constructed will be described. By applying a drive current I from a current supply source (not shown) to the tracking coil 414 shown in FIG. 11, the mover is driven in the rotation direction of the rotation shaft 415, that is, the tracking direction. When a disc (not shown) with a different base material thickness is set in the optical disc device, the disc is discriminated by the disc discriminating means such as the amplitude difference of the focus error signal, and recording / reproducing is performed by switching to the objective lens corresponding to the disc. Be seen.
This switching of the objective lens is performed by applying a pulse current having a short constant time width shown in FIG. 12 to the tracking coil 414 and, for example, as shown in FIG. 10, a magnetic body attracted and positioned by the permanent magnets 412a, 413a and 412b, 413b. This is performed by rotating the mover to a position where the pieces 419b and 419d switch to the magnetic pieces 419a and 419c. Here, the first waveform of the pulse current is a moving pulse for switching, and the second waveform is a braking pulse for braking so that the mover does not move too much.

On the other hand, as another example of the conventional technique, FIG.
As shown in FIG. 3, fins 422 protrude from the bottom of the lens holding member 421, and a position detection sensor 423 is attached to the base 424 so that the fins 422 pass through the upper surface when the lens holding member 421 rotates. . When the objective lens is switched, it is determined which objective lens is selected. When the objective lens 425 is selected, the fin 422 is located inside the position detection sensor 423. On the other hand, when the objective lens 426 is selected, the fin 422 is located outside the position detection sensor 423. Therefore, it is possible to detect which objective lens is currently selected from the output of the position detection sensor 423.

[0009]

In this optical recording / reproducing apparatus, when the magnetic piece embedded in the lens holding member is located at a portion where the magnetic attraction force of the permanent magnet does not act,
That is, if the objective lens cannot be positioned in the center of the optical path of the light and it stops between the objective lenses, it will be difficult to return to the position where the magnetic attraction force acts and it will not operate normally, so a stable configuration of lens switching operation is required. Has been done.

Further, in order to switch, a pulse current having a short constant time width is applied to move and brake, but since the lens holding member constitutes a magnetic circuit, as is well known, a certain primary resonance point by a magnetic spring is set. When held and operated, it resonates at this resonance frequency. With a short fixed time pulse current, the braking pulse will end during resonance, and the resonance will not stabilize, or it will take some time to stabilize and will interfere with the next operation. Is required.

Further, a position detection sensor must be attached to detect which objective lens is selected,
Reduction of the number of parts is required.

It is an object of the present invention to provide an optical recording / reproducing apparatus having a simple structure and stable objective lens switching control characteristics.

[0013]

Means for Solving the Problems The present invention to solve this problem, the two objective lenses even without least characteristics that correspond to different optical recording medium, a lens holding member for holding the objective lens a fixed shaft for supporting the lens holding member slidably and rotatably to position the objective lens on the optical path from the light source, a base for fixing the fixing shaft in a substantially upright, the lens holding member by the electromagnetic force times And a magnetizing magnet which corresponds to an optical path position where the objective lens is on the optical path and an intermediate position where an intermediate rotation angle of each objective lens is on the optical path. And the magnet
Carp with a ferromagnetic core that moves relative in a magnetic field due to
The lens circuit holds the rotation of the lens holding member and supports multiple optical path positions.
The magnetic circuit that
It is characterized by a strong bond .

As a result, the lens holding member is rotatably fixed by the static magnetic force between the optical path position and the intermediate position where the rotation can be controlled by the dynamic electromagnetic force. An optical recording / reproducing apparatus capable of stable and reliable lens switching operation with a simple structure that also serves as a tracking adjustment mechanism, because it is difficult for the lens switching operation to become unstable due to rotation due to difficulty in returning to the operating position. realizable.

Further, the three types of pulse currents of the rotation driving means can surely perform the lens switching regardless of whether the lens holding member is at the optical path position or the intermediate position.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention is an optical recording / reproducing apparatus for irradiating light from a light source to an optical recording / reproducing medium through an objective lens to record / reproduce information.
Characteristics and is small without <br/> least two objective lenses that correspond to different optical recording medium, a lens holding member for holding said objective lens, to place the objective lens on an optical path from the light source wherein comprising a fixed shaft of the lens holding member for rotatably supporting slide, a base for fixing the fixing shaft in a substantially upright, and a rotating means for rotating the lens holding member by the electromagnetic force, the The rotating means corresponds to an optical path position where the objective lens is on the optical path and an intermediate position where the intermediate rotation angle of each objective lens is on the optical path .
The magnetized magnet and the magnet move relative to each other in the magnetic field.
Circuit having a ferromagnetic core
Accordingly, fixing and holding the rotation of the lens holding member when co
A magnetic circuit corresponding to each of the plurality of optical path positions.
The path is magnetically connected from the magnetic circuit corresponding to the intermediate position.
A characterized in that the coupling is strong, the position can be controlled rotation by dynamic electromagnetic force in the optical path position and the intermediate position, so as to rotate the fixed lens holding member by a static magnetic force Since it is difficult to return to the position that acts on the magnetic attraction force and the lens switching operation due to rotation becomes unstable, the lens switching operation is stable and reliable with a simple configuration that also serves as a trekking adjustment mechanism. It is possible to realize an optical recording / reproducing device capable of

[0017] The invention according to claim 2 of the present invention, with respect to those of claim 1, comprising a rotary drive means for electromagnetic induction current flows in the coil of the rotating means, the rotation drive means, pulse amplitude And 3 types of pulse currents having different pulse widths and pulse polarities are output respectively, and regardless of the position of the lens holding member, the lens holding member is first rotated and held on the optical path position, and then the intermediate position. After the lens is rotated to the position, the lens is surely switched by rotating to the optical path position to be switched.

According to a third aspect of the present invention, when the objective lenses are switched, the rotation driving means sets three types of pulse currents as one set, and has three or more objective lenses. It can also be applied to an optical recording / reproducing apparatus, and even when the objective lens is switched over by jumping over one objective lens, it can be performed in the same manner as the switching between adjacent objective lenses.

According to a fourth aspect of the present invention, the electromagnetic force generated by the rotation driving means at the intermediate position is greater than the electromagnetic force generated by the rotation driving means at the optical path position. large, among the three kinds of pulse current generated by the rotary drive means, a third pulse at the beginning and end of the first pulse, which was characterized by a second pulse by riff width is small By electromagnetically generating in a short time at an intermediate position where the static magnetic circuit coupling is weak, switching from the intermediate position to the optical path position can be performed quickly, and switching between lenses can be performed with a small time delay.

According to a fifth aspect of the present invention, the first pulse and the third pulse generated by the rotation driving means have amplitude-decreasing periods in which the amplitude gradually decreases to a substantially constant amplitude substantially constant period. /> There is a while, the amplitude substantially fixed dates characterized in shorter than the period of the amplitude reduction, resonance by magnetic circuits that occur when switched to the optical path position, asymptotically vibration By pressing, the lens can be switched quickly and surely.

The invention according to claim 6 is characterized in that the pulse widths of the first pulse and the third pulse generated by the rotation driving means are larger than the pulse width of the second pulse. By increasing the electromagnetic force generated at the intermediate position where the static magnetic circuit coupling is weak, the intermediate position can be switched to the optical path position quickly, and the switching between the lenses can be performed with a small time delay.

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a perspective view showing the structure of an optical recording / reproducing apparatus according to a first embodiment of the present invention, and FIG.
FIG. 3 is a diagram showing the operation process of driving the objective lens with the passage of time of the electric pulse means of the optical recording / reproducing apparatus in the first embodiment, and FIG. 3 is an exploded perspective view of the optical recording / reproducing apparatus in the first embodiment of the present invention. FIG. 4 is a schematic configuration diagram of an optical recording / reproducing apparatus according to the first embodiment of the present invention, and FIGS. 5 (a), 5 (b) and 5 (c) are the first embodiment of the present invention. 6 is a plan view of the optical recording / reproducing apparatus in FIG. 6, FIG. 6 is a configuration diagram of a tracking magnet and a tracking coil in the first embodiment of the invention, and FIGS. 7 and 8 are diagrams of the tracking magnet in the first embodiment of the invention. It is a schematic diagram which shows the polar arrangement and the relationship of pulse current.

First, the structure of driving the objective lens of the optical recording / reproducing apparatus of the present invention will be described. 1 to 4, reference numerals 1a and 1b are objective lenses for forming a laser spot on the information recording surface of the disc 18, and a plurality of objective lenses 1a and 1b are prepared corresponding to discs such as CDs and DVDs having different substrate thicknesses. Reference numeral 2 is a lens holding member which holds a plurality of objective lenses and which has a bearing 2a and is made of a lightweight and highly rigid synthetic resin material or the like. The rotary shaft 3 is held on the base 7 in a direction substantially perpendicular to the disc, and the lens holding member 2 can be freely moved around the rotary shaft 3 in the rotational and sliding directions, that is, the tracking direction and the focus direction. To hold. A coating of fluororesin or the like is formed on the surface of the rotating shaft 3 to reduce the contact friction resistance with the lens holding member bearing portion 2a. The base 7 is fixed to a head base (not shown) by means of springs and adhesion. The focus coil 9 (see FIG. 3) has a cylindrical shape fixed to the lens holding member 2 so as to be coaxial with the bearing portion 2b, and has a magnetic gap formed by the focus magnets 6a and 6b adhesively fixed to the base 7. It is located inside. The tracking coils 8a and 8b are fixed to an outer diameter position of the lens holding member facing the center O on a straight line Mm passing through the center O of the rotary shaft 3 by dividing the straight line connecting the lens centers into two equal parts. 8a and 8b are electrically connected in series connection. 4a, 4
b and 4c and 4d respectively constitute a pair of tracking magnets, and a straight line Nn on the base 7 passing through the center O of the rotating shaft 3
It is adhered and fixed to the wall surface of the base 7 facing the axis center at Ll. The angle formed by the straight lines Nn and Ll is substantially the same as the angle α formed by the straight line connecting the centers of the objective lenses 1a and 1b and the center O of the rotary shaft 3. Further, each tracking magnet is magnetized in two poles in the rotational tangential direction of the lens holding member 2.

Like the tracking coil, the magnetic plates 10a and 10b are arranged at the lens holding member outer diameter position facing the center O on the straight line Mm. The magnetic plates 10a, 10b are the tracking magnets 4a, 4b or 4c, 4 which face each other.
Since it is attracted to the center position of the two-pole magnetization of d, the lens holding member 2 is positioned and a midpoint restoring force in the tracking direction and the focus direction is generated. Reference numeral 5 is an intermediate position magnet that is magnetized in two poles like the tracking magnets 4a, 4b, 4c and 4d, and divides the angle formed by the straight lines Nn and Ll on the base 7 through the center O of the rotary shaft 3 into two equal parts. It is adhered and fixed to the wall surface of the base 7 by a straight line Pp. Even if neither of the objective lenses 1a and 1b is located in the optical path 12 of the light beam, the lens holding member is provided with the lens holding member at an intermediate position of the arrangement of the magnetic circuit constituted by the tracking magnets 4a, 4b and 4c and 4d. Even when the straight line connecting the two lens centers is divided into two and the straight line Mm passing through the center O of the rotary shaft 3 coincides with the straight line Pp, the driving force can be generated in the tracking direction. In this intermediate magnetic circuit, the drive sensitivity (electromagnetic force) at a frequency lower than the primary resonance frequency of the magnetic spring configured by the intermediate position magnet 5 and the magnetic plate 10a.
Is larger than the driving sensitivity (electromagnetic force) at a frequency lower than the primary resonance frequency of the magnetic spring constituted by the tracking magnets 4a, 4b and 4c, 4d and the magnetic plates 10a, 10b.

By supplying a drive current to the focus coil 9 through the power supply means 20 made of a soft material such as a polyimide resin flexible printed circuit board, the focus coil 9 placed in the constant magnetic field of the focus magnets 6a and 6b is subjected to Fleming's operation. According to the law, an electromagnetic force is generated in the axial direction of the rotating shaft, that is, the sliding direction, and the lens holding member 2 serving as a mover is operated to perform the focus operation for correcting the defocus of the light beam caused by the rotation of the disk 18. . Similarly, by supplying a driving current to the tracking coils 8a and 8b, the tracking coils 8a and 8b placed in the constant magnetic field of the opposing tracking magnet pair 4a, 4b or 4c, 4d apply a driving force in the lens holding member rotating direction. A tracking operation is performed to correct the deviation between the optical disk focal position in the radial direction and the disk track, which occurs in accordance with the rotation of the disk 18.

In FIG. 4, the optical recording / reproducing apparatus has a plurality of optical systems, and when the optical path 12a or 12b having the optimum optical characteristics is selected according to the type of the disk, the semiconductor laser 13a or 13b as the light source is selected. A light beam is emitted from the optical system, rises through a group of mounted optical elements, becomes substantially perpendicular to the disc by a mirror 11a or 11b, and is focused on an information recording surface on the disc 18 through an objective lens 1a or 1b. Recording and playback of. As is well known, the reflected light from the disk is detected by the photodetectors 17a and 17b as an optical signal and converted into an electric signal, and passes through an amplifier (head amplifier, not shown) to a control device (not shown). Is entered. As is well known, the optical recording / reproducing apparatus includes a laser driving circuit, a disc discriminating means, a disc motor for rotating the disc 18, a motor driving circuit therefor, a control device for processing an input signal and issuing a command to each circuit. Etc. (not shown above).

Next, the objective lens drive position and the lens switching operation will be described. In the state of FIG. 5A, the objective lens 1a is positioned at the lens driving regular position by the tracking magnets 4a and 4b and the magnetic plates 10a and 10b and is interposed in the optical path 12 of the light beam. Here, when a disc having a substrate thickness corresponding to the objective lens 1b is set, the objective lens 1b is selected by the disc discriminating means (not shown) utilizing the difference in the laser reflected light amount. Then, a pulsed drive current, which is the three kinds of electric pulse means 24 shown in FIG. 2, is applied to the tracking drive current.
Here, regarding the three types of pulsed drive currents, the magnitude of the first pulse current 21 is smaller than the magnitude of the second pulse current 22, and the time width of application of the first pulse current 21 is the second. The time width of the second pulse current 22 is made larger. Further, the electromagnetic force formed in the intermediate magnetic circuit by the first pulse current 21 is of such a magnitude that it can be rotationally moved from the position of the intermediate magnetic circuit into the tracking magnetic circuit in the adjacent drive normal position, and the drive normal Position tracking The size is such that it cannot be rotated and moved outside the magnetic circuit. The first pulse current 21 is a process 21b that decreases from a constant magnitude 21a over time, and the time of the constant magnitude 21a is smaller than the time of the decreasing process 21b. The resonance of the lens holding member 2 can be sufficiently damped by the time the second pulse current is applied. As a result, the objective lens can be switched from the position of the intermediate magnetic circuit to the drive normal position, and from the drive normal position, the objective lens can be sufficiently braked without moving to the position of the intermediate magnetic circuit, and the second state can be obtained in a stable state without resonance. By rotating the mover by the th pulse current, the mover can be rotated and the lenses can be switched until the objective lens 1b moves to the position of the laser optical axis, that is, the drive position of FIG. 5B. Since the second pulse current 22 has a short time width and is applied with a large pulse current, the second pulse current 22 passes through without being affected by the magnetic attraction force of the intermediate position magnet, and reaches a desired position, in this case the position of FIG. 5 (b). Can be switched to.

The magnitude of the third pulse current 23 is smaller than the magnitude of the second pulse current 22, and the time width of the application of the third pulse current 23 is the time of the second pulse current 22. It is larger than the width. Further, the third pulse current 23 is a process 23b that decreases from a constant magnitude 23a with time, and the time of the constant magnitude 23a is shorter than the time of the decreasing process 23b. The resonance of the lens holding member 2 that occurs at the time of switching by the second pulse current 22 is sufficiently damped. At this time, the straight line M of the lens holding member 2
m and the straight line Nn of the base 7 are substantially the same straight line. The tracking drive at this drive position is performed by the tracking magnet 4 at a position facing the tracking coils 8a and 8b.
Recording and reproduction can be performed on the disc by performing steps c and 4d.

When a disk having a substrate thickness corresponding to the objective lens 1b is set in the state of FIG. 5 (c), as described above, the first pulse current 21 of the three types of pulse-shaped drive currents is used as an intermediate value. A driving force is generated between the position magnet 5 and the tracking coil 8a, and the objective lens 1a is once in the selected position, that is, the state of FIG.
The lens can be switched by rotating the mover until b moves to the position of the laser optical axis, that is, the drive position of FIG. 5B.

When a disk having a substrate thickness corresponding to the objective lens 1b is set in the state of FIG. 5 (b), the driving force is generated by the second pulse, and the lens holding member 2 is moved in the direction without the objective lens. It causes the movement to rotate to. In this case, by providing a rotation stopping projection (not shown) on the lower surface of the lens holding member 2 so as not to rotate more than necessary, the objective lens 1b is positioned at the original drive position without being switched. be able to.

Similarly, FIG. 5 (a), FIG. 5 (b), and FIG.
The operation of switching from the state of (c) to the objective lens 1a can be realized by exchanging the positive and negative of the three types of pulsed drive currents for switching to the objective lens 1b.
By switching the position of the laser optical axis, that is, FIG.
Recording and reproduction can be performed on the disc at the drive position of the position. At this time, the straight line Mm of the lens holding member 2
And the straight line Ll of the base 7 is substantially the same straight line. The tracking coil 8 is used for tracking drive at this drive position.
tracking magnets 4a at positions facing a and 8b,
4b.

FIG. 6 is a view showing the polar arrangement of the tracking coil 8 and the tracking magnet 4, and FIGS. 7 and 8 are the polar arrangement of the tracking magnet 4 and the intermediate position magnet 5 and three kinds of pulse currents which are electric pulse means. It is a figure which shows a relationship.

As shown in FIG. 6, the direction in which the driving force f acts, that is, the direction of rotational movement is determined by the polarity of the tracking magnet 4 and the direction in which the pulse current flows. As shown in FIG. 7, when the polarity of the tracking magnet at the drive normal position and the polarity of the intermediate position magnet are opposite, the first pulse current and the second pulse current
The second pulse current has the same direction. As shown in FIG. 8, when the polarity of the tracking magnet at the drive normal position and the polarity of the intermediate position magnet are the same, the first pulse current and the second pulse current are in opposite directions. As described above, according to this embodiment, the polarity of the magnet and the direction of the pulse current can be selected according to the application.

As described above, according to the present embodiment, the tracking magnetic circuit is formed at the drive normal position and the position of the intermediate magnetic circuit, and the pulse current, which is the three kinds of electric pulse means, is applied. With such a configuration, a lens position detection sensor is not required, the number of parts is small, and switching can be surely selected regardless of where the objective lens is located, and stable and highly reliable objective lens switching characteristics can be obtained.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to FIG. Figure 9
(A) is a block diagram of an optical recording / reproducing apparatus according to a second embodiment of the present invention, and (b) is an electric pulse for switching an objective lens of the optical recording / reproducing apparatus according to the second embodiment of the present invention. FIG. 6 is a current waveform diagram by 9 (a) and 9 (b), parts that are the same as or correspond to those in FIGS. 1 to 8 are given the same reference numerals. The configuration and operation of driving the objective lens will be described in Embodiment 1 and is the same as the configuration shown in FIG.

As shown in FIGS. 9 (a) and 9 (b), the objective lens 41a is placed so as to be interposed in the optical path 12 of the laser.
When is selected, the tracking magnetic circuit includes tracking coils 48a and 48b opposed to the tracking magnets 44a and 44c, and magnetic plates 50a and 50b embedded in the lens holding member 2 as in the first embodiment, although not shown. Has been done. Similarly, when the objective lens 41b is selected, the tracking magnetic circuit moves to the tracking magnet 4
Tracking coils 48b, 4 facing 4b, 44d
8a, magnetic plates 50b, 50a, objective lens 41c
When is selected, the tracking magnetic circuit is constituted by tracking coils 48b and 48a facing the tracking magnets 44a and 44c, and magnetic plates 50b and 50a. An intermediate position magnet 45a is arranged between the tracking magnets 44a and 44b, an intermediate position magnet 45b is arranged between the tracking magnets 44b and 44c, and an intermediate position magnet 45c is arranged between the tracking magnets 44c and 44d. 44
An intermediate position magnet 45d is arranged in the middle of a. When switching from the objective lens 41a to 41b, three types of electrical pulse means 24 similar to those described in the first embodiment are used.
It can be switched with a. Further objective lens 41
When switching from a to 41b and 41c, it can be switched by continuously applying three kinds of electric pulse means 24a and 24b. Even at the intermediate position, a rotational force for switching is generated by the intermediate magnetic circuit, and switching can be performed as in the first embodiment. 9A and FIG.
The explanation in (b) is for the case of three objective lenses, but even if more objective lenses are mounted, a desired objective lens can be used as a laser by applying a plurality of magnetic circuit configurations and three kinds of electric pulse means a plurality of times. It can be switched so as to intervene in the optical path.

As described above, according to the present embodiment as well, a plurality of tracking magnetic circuits are formed at the drive normal position and the intermediate magnetic circuit position as described in the first embodiment, and three kinds of electric pulse means are used. By applying a certain pulse current multiple times, the optical recording / reproducing device does not require a lens position detection sensor with a simple configuration, and the number of parts is small,
You can switch and select wherever the objective lens is located,
The effect of obtaining a stable and highly reliable objective lens switching characteristic can be realized.

In the embodiment, a tracking coil is attached to the rotating lens holding member 2 and the base 7 is attached.
A tracking magnet and an intermediate position magnet are attached to the so-called MC (moving coil) type configuration, but conversely,
An MM (moving magnet) type structure in which a focus magnet and a tracking magnet are attached to the lens holding member and a coil is attached to the base may be used.

Further, in the above-described embodiment, the semiconductor laser, the beam splitter, the rising mirror, and the photodetector are respectively arranged so as to cope with the disks having different characteristics by changing the wavelength and the optical path length of the semiconductor laser. Although it has been described that the optical system has two optical systems, it is not necessarily limited to this, and an objective that has a single semiconductor laser (fixed wavelength) and a single optical system and finally focuses on a disc. The same applies to a configuration in which only the lenses are switched.

Furthermore, the above-described embodiment has a basic configuration, and it is possible to make changes in details within the scope of the rights of the present invention and to add a conventionally known technique, and an optical disk is used as the recording / reproducing medium. Although described with respect to the apparatus, the present invention can be used in a similar apparatus in which the objective lens needs to be switched, such as an apparatus using an optical card or an optical tape as a recording / reproducing medium.

[0041]

As described above, according to the present invention, the tracking magnetic circuit is formed at the drive normal position and the intermediate magnetic circuit position, and the pulse current, which is three kinds of electric pulse means, is applied. In the optical recording / reproducing apparatus, the number of parts can be reduced, and the simple configuration enables the switching and selection regardless of the position of the objective lens, and the advantageous effect of obtaining stable and reliable objective lens switching characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration perspective view of an optical recording / reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of an operation process of driving an objective lens with time of an electric pulse means of the optical recording / reproducing apparatus according to the first embodiment of the present invention.

FIG. 3 is an exploded perspective view of the optical recording / reproducing apparatus according to the first embodiment of the present invention.

FIG. 4 is a configuration diagram of an optical recording / reproducing device according to a first embodiment of the present invention.

FIG. 5 is a plan view of the optical recording / reproducing apparatus according to the first embodiment of the present invention.

FIG. 6 is a configuration diagram of a tracking magnet and a tracking coil according to the first embodiment of the present invention.

FIG. 7 is a diagram showing the relationship between the polarity arrangement of the tracking magnet and the pulse current according to the first embodiment of the present invention.

FIG. 8 is a diagram showing the relationship between the polarity arrangement of the tracking magnet and the pulse current according to the first embodiment of the present invention.

FIG. 9 is a plan view of an optical recording / reproducing device according to a second embodiment of the present invention.

FIG. 10 is a plan view of an optical recording / reproducing apparatus having a conventional objective lens switching mechanism.

FIG. 11 is a schematic diagram showing the shape of a tracking coil mounted on a conventional optical recording / reproducing apparatus.

FIG. 12 is a tracking coil current waveform diagram for switching the objective lens in the conventional optical recording / reproducing apparatus.

FIG. 13 is a plan view showing another example of an optical recording / reproducing apparatus having a conventional objective lens switching mechanism.

[Explanation of symbols]

1a Objective lens 1b Objective lens 2 Lens holding member 3 rotation axes 4a tracking magnet 4b tracking magnet 4c tracking magnet 4d tracking magnet 5 Intermediate position magnet 6a Focus magnet 6b Focus magnet 7 base 8a tracking coil 8b tracking coil 8c tracking coil 8d tracking coil 9 Focus coil 10a Magnetic plate 10b Magnetic plate 11 Launch mirror 12 optical paths 13a, 13b Semiconductor laser 18 discs 21 1st pulse current 22 Second pulse current 23 Third pulse current 24 Electric pulse means

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaya Kuwahara 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP 10-302274 (JP, A) JP 9 -180218 (JP, A) JP-A-8-221779 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G11B 7/09

Claims (6)

(57) [Claims] 1. A optical recording and reproducing apparatus for recording and reproducing by irradiating the information in the optical recording and reproducing medium through an objective lens to light from a light source, no less properties that correspond to different optical recording medium <br / > Two objective lenses, a lens holding member that holds the objective lens, and a fixed shaft that rotatably and slidably supports the lens holding member so that the objective lens is arranged on the optical path from the light source. A base for fixing the fixed shaft substantially upright, and a rotating means for rotating the lens holding member by an electromagnetic force, wherein the rotating means is an optical path position where the objective lens is on the optical path. And a magnetized magnet corresponding to an intermediate position where the rotation angle middle of each of the objective lenses is on the optical path, and a magnetized by the magnet.
A coil portion having a ferromagnetic core that moves relative to the field
The lens holding member is fixedly held by a magnetic circuit provided with, and the lens holding member is paired with each of the plurality of optical path positions.
The corresponding magnetic circuit corresponds to the magnetic circuit corresponding to the intermediate position.
An optical recording / reproducing device characterized by having a stronger magnetic coupling than an air circuit . 2. A rotation drive means for electromagnetically inducing a current by causing a current to flow through a coil of the rotation means, wherein the rotation drive means outputs three kinds of pulse currents having different pulse amplitudes, pulse widths and pulse polarities. The optical recording / reproducing apparatus according to claim 1, wherein 3. The optical recording / reproducing apparatus according to claim 2 , wherein when the objective lens is switched, the rotation driving means sets three kinds of pulse currents as one set. 4. The electromagnetic force generated by the rotary drive means at the intermediate position is larger than the electromagnetic force generated by the rotary drive means at the optical path position, and generated by the rotary drive means. Of the three pulse currents, the first pulse at the beginning and the third pulse at the end are the second pulses.
One of claims 2 or 3, wherein the riff small width
Optical recording and reproducing apparatus of the crab according. 5. A first pulse and a first pulse generated by the rotation driving means.
Beauty third pulse claim whose amplitude has a gradually decreasing amplitude decrease period a substantially constant amplitude substantially fixed period, the amplitude substantially constant period, characterized in that shorter than the period of the amplitude reduction 4. The optical recording / reproducing apparatus according to item 4 . 6. A first pulse and a first pulse generated by the rotation driving means.
Beauty pulse width of the third pulse, an optical recording reproducing apparatus according to claim 4, wherein a greater than the pulse width of the second pulse.