JP2000182259A - Optical recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an optical recording and reproducing device to easily switch and select an objective with simple constitution and have stable objective switching characteristics. SOLUTION: The device is mounted with objectives 1 (1a and 1b) the one of which is interposed selectively in an optical path according to the kind of a disk; and the device has plural magnetic circuit constitution where tracking magnetic circuits which are composed of tracking magnets 4 (4a to 4d), tracking coils 8 (8a and 8b) and magnetic plates 10 (10a and 10b) and arranged at the positions corresponding to the objectives 1 and an intermediate position magnet 5 is arranged at nearly intermediate position where the objectives 1 are disposed; and electric signals supplied to the tracking coils 8 for lens switching have 3 electric pulses 21, 22, and 23.

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, a device for recording and reproducing information using a disk-shaped optical recording / reproducing medium (hereinafter, referred to as a disk) (hereinafter, referred to as an optical disk device) has advantages of large capacity and high speed. It is widely used for voice, image and data recording. Recent optical disk devices include, for example, CDs and CD-ROMs (Read Only Memory).
y), not only reproduction or recording of CD-R (Rewritable), but also DVD (Digital Vers)
It is becoming possible to perform recording and reproduction of discs having different track pitches, such as aty discs, with a single optical disc apparatus. Since characteristics such as substrate thickness and recording density are different between CD and DVD, an optical recording / reproducing apparatus mounted on an optical disc apparatus has an objective lens and a wavelength different in focal length and numerical aperture (NA) corresponding to each disc. 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 disk.

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

Hereinafter, FIGS. 10, 11, 12 and 13 will be described.
A conventional objective lens switching type optical recording / reproducing apparatus 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. FIG. 11 is a view showing the shape of a tracking coil mounted on the conventional optical recording / reproducing apparatus.
FIG. 12 is a diagram showing a waveform of a current flowing through a tracking coil for switching an objective lens in a conventional optical recording / reproducing device, and FIG. 13 is a plan view showing another example of an optical recording / reproducing device having a conventional objective lens switching mechanism. It is.

In FIG. 10, objective lenses 407a and 407b corresponding to disks having different substrate thicknesses and recording densities, a tracking coil 41 are provided on a lens holding member 402.
4a, 414b, 414c, 414d, 414e, 41
4f is bonded and fixed to form a mover, and is capable of rotating around the rotation shaft 415 and sliding in the axial direction. The mover rotates and the tracking coils 414a, 4a
14b, 414c, 414d, 414e, and 414f are located at positions facing the permanent magnets 412a, 413a, and 412f.
b and 413b are provided to form a magnetic circuit. The lens holding member 402 has a tracking coil 414a.
And 414b, 414b and 414c, 414d and 414e, and 414e and 414f, respectively.
Are embedded, and the permanent magnets 412a, 413a and 4
Positioning in the rotational and sliding directions of the mover is performed by the magnetic attraction force generated between the movable element 12b and 413b.

Next, the operation of the conventional optical recording / reproducing apparatus thus configured 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 rotating shaft 415, that is, in the tracking direction. When a disc (not shown) having a different base material thickness is set in the optical disc apparatus, the disc is discriminated by disc discriminating means such as a difference in amplitude of a focus error signal, and recording and reproduction are performed by switching to an objective lens corresponding to the disc. Will be
This switching of the objective lens is performed by applying a pulse current having a short fixed time width shown in FIG. 12 to the tracking coil 414, and for example, as shown in FIG. 10, a magnetic material attracted and positioned by the permanent magnets 412a, 413a and 412b, 413b. The operation is performed by rotating the mover until the pieces 419b and 419d are switched to the magnetic pieces 419a and 419c. Here, the first waveform of the pulse current is a movement pulse for switching, and the second waveform is a braking pulse for braking the mover so as not to move too much.

On the other hand, as another example of the prior art, FIG.
As shown in FIG. 3, a fin 422 protrudes from the bottom of the lens holding member 421, and a position detection sensor 423 is attached to the base 424 so that the fin 422 passes over the upper surface when the lens holding member 421 rotates. . At the time of switching the objective lens, it is determined which objective lens is selected. When the objective lens 425 is selected, the fin 422 is located in 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 from the output of the position detection sensor 423 which objective lens is currently selected.

[0009]

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

In order to perform switching, a pulse current having a short fixed time width is applied to move and brake. However, since the lens holding member forms a magnetic circuit, a certain primary resonance point by a magnetic spring is established as is well known. When held and operated, it resonates at this resonance frequency. With a short pulse current of a fixed time width, the braking pulse ends during resonance, and the resonance is not stable, or it takes time to stabilize, and it interferes with the next operation. Is required.

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

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical recording / reproducing apparatus having a simple configuration and a stable objective lens switching control characteristic.

[0013]

SUMMARY OF THE INVENTION To solve this problem, the present invention provides at least two objective lenses respectively corresponding to optical recording / reproducing media having different characteristics, a lens holding member for holding the objective lens, and a light source. A fixed shaft that rotatably and slidably supports the lens holding member, and a base that fixes the fixed shaft substantially upright so that the objective lens is arranged on the optical path from
Rotating means for rotating the lens holding member by electromagnetic force, wherein the rotating means has an optical path position at which the objective lens is on the optical path and an intermediate position at which the intermediate rotation angle of each objective lens is on the optical path. And the rotation of the lens holding member is fixed and held. In particular, the rotation means relatively moves the magnetized magnet corresponding to the plurality of optical path positions and the intermediate position and the magnetic field generated by the magnet. A magnetic circuit comprising a moving coil member having a ferromagnetic core, and a magnetic circuit formed by a magnet and a coil portion corresponding to a plurality of optical path positions has stronger magnetic coupling than a magnetic circuit formed by a magnet and a coil portion corresponding to an intermediate position. It is characterized by the following. In addition, there is provided a rotation driving means for causing a current to flow through the coil of the rotation means to induce electromagnetic induction, and the rotation driving means outputs three kinds of pulse currents having different pulse amplitudes, pulse widths, and pulse polarities. It is assumed that.

Thus, the lens holding member is rotated and 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 that can perform stable and reliable lens switching operation with a simple configuration that also uses a tracking adjustment mechanism by eliminating the difficulty of returning to the operating position and making the lens switching operation unstable due to rotation. realizable.

[0015] Further, the three kinds of pulse currents of the rotation driving means can reliably switch the lens, regardless of whether the lens holding member is at the optical path position or the intermediate position.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is an optical recording / reproducing apparatus for recording / reproducing information by irradiating light from a light source to an optical recording / reproducing medium through an objective lens,
At least two objective lenses respectively corresponding to optical recording / reproducing media having different characteristics, a lens holding member for holding the objective lens, and the lens holding member such that the objective lens is arranged on an optical path from the light source. A fixed shaft that is rotatably slidably supported, a base that fixes the fixed shaft substantially upright, and a rotating unit that rotates the lens holding member by electromagnetic force; The rotation of the lens holding member is fixedly held at an optical path position where the objective lenses are on the optical path and an intermediate position where the rotation angle between the objective lenses is on the optical path. According to a second aspect of the present invention, the rotating means comprises:
A magnet corresponding to the plurality of optical path positions, comprising a magnetized magnet corresponding to the plurality of optical path positions and the intermediate position, and a coil portion having a ferromagnetic core, which relatively moves in a magnetic field by the magnet. And the magnetic circuit by the coil portion is characterized by stronger magnetic coupling than the magnetic circuit by the magnet and the coil portion corresponding to the intermediate position, and is a position where rotation can be controlled by dynamic electromagnetic force. Since the lens holding member is rotated and fixed between the optical path position and the intermediate position by a static magnetic force, it is difficult to return to the position acting on the magnetic attraction force, and the lens switching operation due to the rotation becomes unstable. Thus, an optical recording / reproducing apparatus that can perform a stable and reliable lens switching operation with a simple configuration that also serves as a tracking adjustment mechanism can be realized.

According to a third aspect of the present invention, in accordance with the second aspect, there is provided a rotation driving means for applying a current to a coil of the rotation means to induce electromagnetic induction, and wherein the rotation driving means comprises:
It is characterized by outputting three kinds of pulse currents with different pulse amplitude, pulse width and pulse polarity, respectively.
Regardless of the position where the lens holding member is located, first, it is rotated and held on the optical path position, then it is rotated to the intermediate position, and then it is rotated to the optical path position to be switched, so that the lens switching is performed reliably. .

According to a fourth aspect of the present invention, when the objective lens is switched, the rotation driving means sets one of three types of pulse currents, and has three or more objective lenses. The present invention can also be applied to an optical recording / reproducing apparatus. In particular, even when one objective lens is jumped and switched when the objective lens is switched, the switching can be performed in the same manner as the switching of the adjacent objective lens.

According to a fifth aspect of the present invention, the electromagnetic force generated by the rotating means at the intermediate position is smaller than the electromagnetic force generated by the rotating means at the optical path position. The first pulse and the third pulse at the end of the three types of pulse currents generated by the rotation driving means are smaller in amplitude than the second pulse. By generating electromagnetic waves 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 sixth aspect of the present invention, the first pulse and the third pulse generated by the rotation driving means have a period in which the amplitude is substantially constant and a period in which the amplitude gradually decreases, and the amplitude is substantially constant. Is characterized in that the period is shorter than the period during which the amplitude is reduced, and resonance caused by the magnetic circuit, which occurs when switching to the optical path position, is asymptotically suppressed, and lens switching is performed quickly and reliably. .

According to a seventh aspect of the present invention, the pulse width of the first pulse and the third pulse generated by the rotation driving means is larger than the pulse width of the second pulse. By increasing the generated electromagnetic force at the 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.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. (Embodiment 1) FIG. 1 is a perspective view showing the configuration of an optical recording / reproducing apparatus according to a first embodiment of the present invention, and FIG.
FIG. 3 is a diagram showing an operation process of driving an objective lens with time of an electric pulse unit of the optical recording / reproducing apparatus according to the first embodiment. 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 schematic diagram of the configuration of an optical recording / reproducing apparatus according to the first embodiment of the present invention, and FIGS. 5 (a), 5 (b) and 5 (c) show 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, and FIGS. 7 and 8 are diagrams of the tracking magnet according to the first embodiment of the present invention. It is a schematic diagram which shows the relationship between a polarity arrangement and a pulse current.

First, the configuration 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 denote objective lenses for forming a laser spot on the information recording surface of the disk 18, and a plurality of objective lenses are prepared corresponding to disks having different base materials such as CDs and DVDs. Reference numeral 2 denotes a lens holding member which holds a plurality of objective lenses and has a bearing portion 2a and is formed of a lightweight and highly rigid synthetic resin material or the like. The rotation shaft 3 is held on the base 7 in a direction substantially perpendicular to the disk, and the lens holding member 2 can freely rotate and slide around the rotation shaft 3 in the tracking direction and the focus direction. Holding so. A coating such as a fluororesin is formed on the surface of the rotating shaft 3 to reduce contact friction resistance with the lens holding member bearing 2a. The base 7 is fixed to a head base (not shown) by means such as a spring and an adhesive. 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 2b, and has a magnetic gap formed by focus magnets 6a and 6b adhered and fixed to the base 7. Is located inside. The tracking coils 8a and 8b are fixed at 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 rotating shaft 3 by dividing a straight line connecting the centers of the lenses into approximately two parts. 8a and 8b are electrically connected in a series connection. 4a, 4
b, 4c and 4d each 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;
Ll is bonded and fixed to the wall surface of the base 7 facing the axis center. The angle formed by the straight lines Nn and Ll is substantially the same as the angle α formed by a straight line connecting the centers of the objective lenses 1a and 1b and the center O of the rotating shaft 3. Each of the tracking magnets is two-pole magnetized in the rotational tangent direction of the lens holding member 2.

The magnetic plates 10a and 10b are arranged at the outer diameter position of the lens holding member facing the center O on the straight line Mm similarly to the tracking coil. The magnetic plates 10a, 10b are opposed to the tracking magnets 4a, 4b or 4c, 4c.
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 return force is generated in the tracking direction and the focus direction. Reference numeral 5 denotes a two-pole magnetized intermediate position magnet similar to the tracking magnets 4a, 4b, 4c, and 4d, which bisects the angle formed by straight lines Nn and Ll on the base 7 passing through the center O of the rotating shaft 3. It is adhesively fixed to the wall of the base 7 at a straight line Pp. This intermediate magnetic circuit allows the lens holding member to be positioned at an intermediate position in the arrangement of the magnetic circuit composed of the tracking magnets 4a, 4b and 4c, 4d, that is, even when neither of the objective lenses 1a and 1b is located in the optical path 12 of the light beam. The driving force can be generated in the tracking direction even when a straight line Mm passing through the center O of the rotating shaft 3 coincides with the straight line Pp by dividing a straight line connecting the centers of the two lenses into two equal parts. In this intermediate magnetic circuit, the drive sensitivity (electromagnetic force) at a frequency lower than the primary resonance frequency of the magnetic spring constituted by the intermediate position magnet 5 and the magnetic plate 10a.
Is higher than the drive sensitivity (electromagnetic force) at a frequency lower than the primary resonance frequency of the magnetic spring composed of 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 a power supply means 20 made of a soft material such as a polyimide resin flexible printed circuit board, the focus coil 9 placed in a constant magnetic field of the focus magnets 6a and 6b can be used for framing. According to the law, an electromagnetic force is generated in the axial direction of the rotation axis, that is, in the sliding direction, and the lens holding member 2 serving as a movable element is operated to perform a focus operation for correcting a defocus of the light beam caused by the rotation of the disk 18. . Similarly, by supplying a drive current to the tracking coils 8a and 8b, the tracking coils 8a and 8b placed in a constant magnetic field of the opposing tracking magnet pairs 4a and 4b or 4c and 4d generate a driving force in the rotation direction of the lens holding member. The tracking operation is performed to correct the deviation between the optical track focal position and the disk track in the radial direction, which occurs according to the rotation of the disk 18.

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

Next, the objective lens driving position and the lens switching operation will be described. In the state shown in FIG. 5A, the objective lens 1a is positioned at the normal lens drive 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 disk having a base material thickness corresponding to the objective lens 1b is set, the objective lens 1b is selected by disk discriminating means (not shown) utilizing a difference in the amount of reflected laser light. Then, pulse driving currents, which are three kinds of electric pulse means 24 shown in FIG. 2, are applied to the tracking driving current.
Here, for 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 pulse width is set to be larger than the time width of the second pulse current 22. The electromagnetic force generated in the intermediate magnetic circuit by the first pulse current 21 is large enough to rotate from the position of the intermediate magnetic circuit into the adjacent tracking magnetic circuit at the normal driving position, and The size is such that the position cannot be rotated out of the tracking magnetic circuit. The first pulse current 21 is a process 21b that decreases from a constant magnitude 21a with the passage of time. The time of the constant magnitude 21a is shorter than the time of the decreasing process 21b. By the time the second pulse current is applied, the resonance of the lens holding member 2 can be sufficiently damped. Thereby, the objective lens can be switched from the position of the intermediate magnetic circuit to the normal driving position, and from the normal driving position, the objective lens is sufficiently moved without moving to the position of the intermediate magnetic circuit, and the second lens is kept in a stable state without resonance. A rotating force is generated in the mover by the second pulse current, and the lens can be switched by rotating the mover until the objective lens 1b moves to the position of the laser optical axis, that is, the drive position in FIG. 5B. Since the second pulse current 22 has a short time width and is applied with a large pulse current, it passes without being affected by the magnetic attraction force of the intermediate position magnet, and passes through a desired position, in this case, the position shown in FIG. 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 the constant magnitude 23a with the lapse of time, and the time that is the constant magnitude 23a is shorter than the time of the decreasing process 23b. The resonance of the lens holding member 2 generated 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 in this drive position is performed by the tracking magnet 4 located at a position facing the tracking coils 8a and 8b.
The recording and reproduction can be performed with respect to the disk by performing steps c and 4d.

When a disk having a substrate thickness corresponding to the objective lens 1b is set in the state shown in FIG. 5C, as described above, the first pulse current 21 of the three types of pulse-like drive currents is intermediate. A driving force is generated between the position magnet 5 and the tracking coil 8a, and the objective lens 1a is once in a selected position, that is, in 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 in FIG. 5B.

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

5 (a), 5 (b) and 5
The operation of switching from the state (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.
To switch the position of the laser optical axis, that is, FIG.
Recording and reproduction can be performed on the disk 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 drive in this drive position is performed by the tracking coil 8.
a, a tracking magnet 4a at a position facing the 8b,
4b.

FIG. 6 shows the polar arrangement of the tracking coil 8 and the tracking magnet 4. FIGS. 7 and 8 show the polar arrangement of the tracking magnet 4 and the intermediate position magnet 5 and three types of pulse currents serving as electric pulse means. It is a figure showing a relation.

As shown in FIG. 6, the direction in which the driving force f acts, that is, the direction of the 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 normal driving position and the polarity of the intermediate position magnet are opposite, the first pulse current and the second
The second pulse current has the same direction. As shown in FIG. 8, when the polarity of the tracking magnet at the normal driving 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. Thus, according to the present 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 normal driving position and the intermediate magnetic circuit position, and pulse currents, which are three types of electric pulse means, are applied. With such a configuration, a lens position detection sensor is unnecessary, the number of components is small, and switching can be reliably selected regardless of where the objective lens is located, and a stable and reliable objective lens switching characteristic can be obtained.

(Embodiment 2) Hereinafter, a second embodiment of the present invention will be described with reference to FIG. FIG.
(A) is a configuration 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. 7 is a current waveform diagram according to FIG. In FIGS. 9A and 9B, the same or corresponding parts as those in FIGS. 1 to 8 are denoted by the same reference numerals. The configuration and operation of driving the objective lens are described in the first embodiment, and are the same as those shown in FIG.

As shown in FIGS. 9A and 9B, the objective lens 41a is interposed in the optical path 12 of the laser.
Is selected, the tracking magnetic circuit is composed of tracking coils 48a and 48b facing the tracking magnets 44a and 44c, and magnetic plates 50a and 50b (not shown) embedded in the lens holding member 2 as in the first embodiment. Have been. Similarly, when the objective lens 41b is selected, the tracking magnetic circuit is
4b, 44d and the tracking coils 48b, 4
8a, composed of magnetic plates 50b, 50a, objective lens 41c
Is selected, the tracking magnetic circuit is composed of the tracking coils 48b, 48a facing the tracking magnets 44a, 44c, and the magnetic plates 50b, 50a. An intermediate position magnet 45a is disposed between the tracking magnets 44a and 44b, an intermediate position magnet 45b is disposed between 44b and 44c, and an intermediate position magnet 45c is disposed between 44c and 44d. 44
An intermediate position magnet 45d is arranged in the middle of a. When switching from the objective lens 41a to the objective lens 41b, three types of electric pulse means 24 are used in the same manner as described in the first embodiment.
It can be switched with a. Furthermore, the objective lens 41
When switching from "a" to "41b" and "41c", switching can be performed by continuously applying three types of electric pulse means 24a and 24b. When the intermediate magnetic circuit is located at the intermediate position, a switching torque is generated by the intermediate magnetic circuit, and the switching can be performed as in the first embodiment. 9 (a), 9
The description of (b) is for the case where three objective lenses are provided. However, even if more than three objective lenses are mounted, a desired objective lens can be mounted on the laser by applying a plurality of magnetic circuit configurations and three types of electric pulse means a plurality of times. It can be switched to be interposed in the optical path.

As described above, also in this embodiment, a plurality of tracking magnetic circuits are provided at the normal drive position and the intermediate magnetic circuit position as described in the first embodiment, and three types of electric pulse means are used. By applying a certain pulse current a plurality of times, in an optical recording / reproducing apparatus, a lens position detection sensor is unnecessary with a simple configuration, and the number of parts is small,
No matter where the objective lens is located, you can switch and select
The effect of obtaining a stable and reliable objective lens switching characteristic can be realized.

In the embodiment, the tracking coil is attached to the rotating lens holding member 2 and
A tracking magnet and an intermediate position magnet are attached to the so-called MC (moving coil) type configuration.
A focusing magnet and tracking magnet may be attached to the lens holding member, and a coil may be attached to the base.

In the above-described embodiment, the semiconductor laser, the beam splitter, the rising mirror, and the photodetector are arranged so as to correspond to disks having different characteristics by changing the wavelength, the optical path length, and the like of the semiconductor laser. Although the description has been made with the two optical systems provided, the present invention is not necessarily limited to this, and the objective includes a single semiconductor laser (fixed wavelength), a single optical system, and finally condenses the light on a disk. The same applies to a configuration in which only the lens is switched.

Further, the above-described embodiment has a basic configuration, and can be carried out with modifications in detail within the scope of the rights of the present invention and also with conventionally known techniques. Although the present invention has been described with reference to an apparatus, the present invention can be used in a similar apparatus that requires switching of an objective lens, such as an apparatus using an optical card or an optical tape as a recording and reproducing medium.

[0041]

As described above, according to the present invention, the tracking magnetic circuit is arranged at the normal drive position and the intermediate magnetic circuit position, and pulse currents, which are three kinds of electric pulse means, are applied. In the optical recording / reproducing apparatus, the number of parts can be reduced, the switching can be selected regardless of the position of the objective lens with a simple configuration, and an advantageous effect of obtaining a stable and reliable objective lens switching characteristic can be obtained.

[Brief description of the 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 showing an operation process of driving an objective lens with time of an electric pulse unit 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 apparatus according to the 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 apparatus 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 device.

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

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

[Explanation of symbols]

 1a Objective lens 1b Objective lens 2 Lens holding member 3 Rotation axis 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 Reference Signs List 9 focus coil 10a magnetic plate 10b magnetic plate 11 rising mirror 12 optical path 13a, 13b semiconductor laser 18 disk 21 first pulse current 22 second pulse current 23 third pulse current 24 electric pulse means

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasuo Nishihara 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Masaya Kuwahara 1006 Kadoma Kadoma, Kadoma City Osaka Pref. F term (reference) 5D118 AA23 AA26 BA01 BB02 DC03 EA02 EB03 EB15 EC03 EC07 ED03 ED08 EE01 EE05 FA06

Claims (7)

[Claims] 1. An optical recording / reproducing apparatus for recording / reproducing information by irradiating light from a light source onto an optical recording / reproducing medium through an objective lens, wherein at least two objective lenses respectively corresponding to optical recording / reproducing media having different characteristics. A lens holding member that holds the objective lens, a fixed shaft that rotatably and slidably supports the lens holding member so that the objective lens is arranged on an optical path from the light source, and A rotating base for rotating the lens holding member by electromagnetic force, wherein the rotating means includes: an optical path position where the objective lens is on the optical path; An optical recording / reproducing apparatus, wherein the rotation of the lens holding member is fixedly held at an intermediate position where the intermediate rotation angle of the lens is on the optical path. 2. The rotating means includes a magnetized magnet corresponding to a plurality of optical path positions and an intermediate position, and a coil portion having a ferromagnetic core, which relatively moves in a magnetic field generated by the magnet. 2. The optical recording / reproducing apparatus according to claim 1, wherein the magnetic circuit formed by the magnet and the coil corresponding to the plurality of optical path positions has stronger magnetic coupling than the magnetic circuit formed by the magnet and the coil corresponding to the intermediate position. apparatus. 3. A rotating drive means for causing a current to flow through a coil of the rotating means and inducing electromagnetic induction, wherein the rotating drive means outputs three kinds of pulse currents having different pulse amplitudes, pulse widths and pulse polarities. 3. The optical recording / reproducing apparatus according to claim 2, wherein: 4. The optical recording / reproducing apparatus according to claim 3, wherein, when the objective lens is switched, the rotation driving means sets one of three types of pulse currents. 5. The electromagnetic force generated by the rotating means at the intermediate position is larger than the electromagnetic force generated by the rotating means at the optical path position, and the rotating means generates the electromagnetic force. 5. The optical recording / reproducing apparatus according to claim 3, wherein an amplitude of the first pulse and an end of the third pulse among the three types of pulse currents are smaller than that of the second pulse. 6. A first pulse generated by the rotation driving means,
6. The optical recording / reproducing apparatus according to claim 5, wherein the third pulse has a period in which the amplitude is substantially constant and a period in which the amplitude gradually decreases, and the period in which the amplitude is substantially constant is shorter than the period in which the amplitude decreases. 7. A first pulse generated by the rotation driving means,
6. The optical recording / reproducing apparatus according to claim 5, wherein the pulse width of the third pulse is larger than the pulse width of the second pulse.