JPH09198677A - Optical information reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To speedily and stably perform the start of reproduction and the recovery from the servo deviation by enabling the device to smoothly change over a lens in accordance with the loaded optical disk and easily decide the state of an objective lens. SOLUTION: A reflection part 30 is provided on a movable part 11 whereon the objective lenses 12, 13 are mounted, and the objective lenses 12, 13 are changed over in such a manner that a kick pulse and a brake pulse are changed over by detecting a changeover timing signal from the reflected light of the reflection part 30 at the time of changing over the objective lenses.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information reproducing apparatus for reproducing information from an optical recording medium such as an optical disk having different physical characteristics by an optical head having a plurality of kinds of objective lenses mounted on one actuator. .

[0002]

2. Description of the Related Art FIG. 28 is a conventional optical information reproducing device (optical head device) disclosed in Japanese Patent Publication No. 6-90800.
FIG. 3 is a perspective view showing an objective lens driving device part of FIG. In the figure, 1a and 1b are objective lenses, 2 is objective lenses 1a and 1b.
A movable part for holding b, 3 is a fixed base, 4a and 4b are elastic supporting members whose one ends are connected to the fixed base 3, 5 is a coil for controlling a focus direction wound around the holder 2, 6a,
6b is a permanent magnet, 7a and 7b are yokes, and 8 is the above 1 to 7
Objective lens driving device composed of a and 7b parts, 9a is laser light incident on the objective lens 1a, 9b is laser light incident on the objective lens 1b, and 10a and 10b are lenses for fixing the objective lenses 1a and 1b. It is a holder.

With respect to the shift of the focus direction, a desired current is passed through the focus direction control coil 5 to move the movable portion 2
Is driven in the direction of arrow A to control the focus direction. If radial feed or track direction control is required,
By passing a desired current through a track direction control coil (not shown), the optical head device including the objective lens driving device 8 is driven in the direction perpendicular to the arrow A direction to perform radial feed,
And track direction control.

As described above, in the conventional example, the plurality of objective lenses for converging the plurality of light beams emitted from the light source unit as different light spots on the information recording medium are integrally held in the holder. Therefore, only one optical head device is required for real-time monitoring or overwriting, and the optical disc reproducing device can be downsized and simplified. In addition, information can be erased, recorded, and reproduced almost in real time.

Further, there is provided a focus control device for controlling the focus position of at least one light spot among the different light spots formed by the plurality of objective lenses, independently of the focus positions of other light spots. Therefore, it is possible to increase the tolerance of the mounting and assembling accuracy of the members, and improve the assembling workability and the productivity.

Further, a tracking control device for controlling the tracking direction position of at least one light spot among the different light spots formed by the plurality of objective lenses independently of the tracking direction positions of other light spots is provided. Therefore, it is possible to increase the tolerance of the mounting and assembling accuracy of the members, and improve the assembling workability and the productivity.

As described above, in the conventional optical head device, two objective lenses are mounted on one actuator movable portion to realize a function such as a real-time monitor. It is naturally conceivable that the optical disc is used to maintain compatibility.
For example, one is a combination of a short wavelength laser and a lens having a high aperture ratio, and the other is a combination of a conventional laser wavelength and a lens having a conventional aperture ratio.

However, having two optical systems as described above not only increases the complexity of the optical system, but also requires each optical system to have focus error detection and track error detection, which results in a large cost increase. Becomes a factor. In particular, if there is only a compatibility problem, there is a problem that one system is completely wasted because the other lens is not used while reproducing one optical disk.

Therefore, a method of mounting the two lenses as described above using an actuator of a type having one optical system and rotating about one axis has been considered. However, in this case, it is necessary to discriminate the type of the disc and to largely rotate the rotary actuator to switch the lens.

In an optical head having two optical systems as shown in the conventional example, it is possible to determine the disc type and the like from the reproduced information by reproducing information simultaneously in each optical system. In the only system, the lens switching and disc determination work described above are the most important works at the start of reproduction. If the disc type cannot be determined, it is impossible to switch lenses as a result, and playback is blindly tried.Therefore, there is a problem of collision between the lens and the disc due to focus pull-in failure, and the life of the focus coil due to overcurrent. In addition to the problem, problems such as a long playback start wait time and a long recovery time from a servo error occurred.

[0011]

In the conventional optical information reproducing apparatus (optical disk apparatus) as described above, since a common optical head reproduces several kinds of disks having different physical characteristics, a plurality of aperture ratios are used. It was necessary to mount objective lenses of different types on the movable part of the actuator. In this case, first it was not possible to know which lens side the current optical head was positioned before playing the optical disc, so a focus search was performed once, and the signal amplitude of the focus error signal at this time and the Discs had to be identified by examining the amount of reflected light near the focal point.
In addition, discriminating the disc for various discs such as discs with a thick substrate, thin discs, or discs with low reflectance without knowing which lens is used makes the determination circuit extremely complicated. There was a problem that the result was uncertain.

Further, at the start of reproduction or when servo is lost due to vibration or the like, if the combination of the disc and the lens is wrong, it is necessary to switch the lens to another one, but it is fixed beforehand. With the kick pulse and the brake pulse, the switching operation of the lens cannot be reliably performed, and there is a problem that it is difficult to start the signal reproduction.

The present invention has been made to solve the above problems. A first object of the present invention is which lens state (position) the present objective lens has without reproducing a signal from a disc. Therefore, it is possible to obtain an optical information reproducing apparatus capable of determining whether or not there is a disc, and smoothly discriminating the disc, and quickly recovering from a reproduction waiting time or a servo misalignment.

A second object is to automatically switch the kick pulse to the brake pulse according to the response of the actuator when the objective lens is switched to a different objective lens. It is intended to obtain an optical information reproducing device capable of performing a stable lens switching operation even when there is a fluctuation of the device or a device vibration.

A third object is to determine the direction in which the movable portion of the actuator is moving during a lens switching operation or an abnormal situation such as a servo loss without reproducing a signal from the disk. In addition to being recognizable, it also instantly recognizes failure of lens switching operation,
An optical information reproducing device capable of performing the switching operation again is obtained.

[0016]

In the optical information reproducing apparatus according to the present invention, when the present objective lens is switched to another objective lens having a different aperture ratio, a timing signal indicating the switching is provided during the lens switching. It is provided with a generating means.

Further, for lens switching, a kick pulse and a brake pulse are continuously applied to a tracking actuator in a movable portion, and a lens kick signal for switching the kick pulse and the brake pulse based on a timing signal generated during the switching. It is provided with a generating means.

Further, in the middle of the plurality of objective lenses, on the side where the optical system is formed, a reflecting portion for reflecting the parallel laser light for signal reading from the optical system in the direction opposite to the incident direction is formed. In addition, a detection circuit for detecting a peak or a level in the amplitude of the light amount detection signal from the reflection section is provided.

Further, in the above-mentioned reflecting section, when the objective lens is switched, if the two lenses have different patterns so that the reflection amount of the parallel laser light for signal reproduction in the optical system varies, the reflectance will be increased. In addition to forming asymmetric patterns in different bright and dark parts or in the track direction, a level detection circuit in the detection signal from the reflection part or a pattern determination circuit for reading the signal pattern is provided.

In addition, the parallel light in the optical system between the plurality of lenses penetrates from the optical system to the disc side in the area other than the lenses, and again the direction of the parallel laser light emitted by the reflecting portion provided in the optical disc or the loading mechanism. A through hole that returns in the opposite direction is provided, and a detection circuit that detects the peak or level in the amplitude of the light amount detection signal of the reflected light that has passed through the through hole is provided.

Further, a plurality of through holes provided in the movable portion are provided between the objective lenses, and the plurality of through holes are arranged so as to have different widths in the track direction.

Further, a counter electromotive force detection circuit for detecting the counter electromotive force generated in the tracking actuator coils corresponding to a plurality of lens positions is provided, and the polarity reversal of the detected counter electromotive force signal is detected. The polarity reversal detection circuit is provided.

Further, in addition to applying a drive signal for switching the lens to the tracking actuator coil,
An AC current applying means for generating an AC magnetic field is provided, and a detection coil for detecting the AC magnetic field and a detection circuit for detecting the amplitude of the detected AC magnetic field amount are provided outside the actuator.

Further, a reflecting portion is attached to the movable portion of the actuator, and a light source different from the laser light for reproducing information is attached to the fixed portion so that the laser light for reproducing information is two lenses when the lens is switched. The photodetector is configured so that the light from the light source can be received from the reflecting portion at a point that crosses the intermediate point.

Further, in an optical head having a movable portion on which a plurality of objective lenses are mounted, an identification signal detector for the objective lenses is provided between or outside the plurality of objective lenses on the moving line of the objective lenses.

Further, reflecting parts are provided on both sides of the moving direction line of the objective lens, and the plurality of objective lenses are configured to be different depending on the presence or absence of the reflecting part and the difference in reflectance. It is a thing.

Further, through holes are formed on both sides of the objective lens in the moving direction, and the presence or absence of the through holes in the plurality of objective lenses, the width of the through holes, or the number of the through holes are different depending on each lens. It is configured as follows.

Further, the reflecting portion is attached to the movable portion of the actuator, and a light source different from the laser light for reproducing information is attached to the fixed portion, and the light from the light source is emitted from the reflecting portion at a point corresponding to a plurality of lenses. The photodetector is configured so that it can receive light.

Further, a reflecting portion or a through hole is provided at an intermediate point on the moving direction line of the plurality of objective lenses, and
A swing signal generating means for swinging the actuator to the left and right and a comparing means for comparing the swing signal with the detection signal from the through hole or the reflecting portion are provided.

Further, the discriminating means based on the output of the discriminating signal detector of the objective lens mounted on the movable part, the focus search circuit for performing the focus search after the discriminating, and the disc for discriminating the disc from the focus error signal at the time of the focus search. A discrimination circuit is provided.

Further, in the case where the kick operation cannot be successfully performed by the means for varying the width of the kick pulse or the drive voltage amplitude in the lens switching means and the lens identification signal detector for specifying the lens after the lens switching operation. Is to increase or decrease the driving force.

Further, a through hole provided in the movable part,
Reflected light amount light receiving means for classifying the type of the disk based on the reflected light from the optical disk obtained through the through hole is provided.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION In an optical information reproducing apparatus according to an embodiment of the present invention, when moving from a current lens to another lens having a different aperture ratio, timing at a switching portion from the lens to the lens Generate a signal.

Further, when the lens is switched by applying the kick pulse and the brake pulse to the tracking actuator, the width of the kick pulse and the timing of applying the brake pulse are set based on the timing signal of the lens switching, thereby the friction The drive amount corresponding to the load fluctuation such as is generated.

Further, by providing a reflecting portion between the plurality of lenses on the side where the optical system of the movable portion is arranged,
Using laser light and photodetector used for normal information reproduction,
A switching timing signal at the time of lens switching is obtained.

Further, by forming a pattern in which light and darkness are generated in the lens shift direction in the reflecting portion, or by constructing the reflecting portion asymmetrically in the tracking direction, based on the fluctuation of the reflected light amount obtained from the reflecting portion when the lens is switched, The pattern matching circuit and the level change detection circuit detect the moving direction at the time of lens switching, and specify the destination lens.

Further, by providing a through hole between a plurality of lenses in the movable part, the parallel laser light for reproducing information in the optical head is penetrated when the lenses are switched and reflected by the optical disk or the reflecting surface of the loading mechanism part. By doing so, the timing signal at the time of lens switching is obtained by the photodetector for information reproduction.

Further, the size and number of the through holes between the plurality of lenses are changed in the lens shift direction, and the switching direction is detected by the pattern matting circuit based on the fluctuation of the reflected light amount at the time of lens switching, and the lens is specified. .

Further, the counter electromotive force generated in the tracking actuator coil is detected by comparing the drive current information obtained from the current detection resistor with the drive voltage information, and when the lens is switched, the actuator coil corresponding to each lens is tracked. By taking out the change in the counter electromotive force generated when passing through the drive magnet, the timing at the time of lens switching is obtained.

Further, an AC signal selected at a frequency that does not affect the operation of the movable section is superimposed on the actuator drive current, and the AC magnetic field from the coil is detected by an AC magnetic field detector provided around the actuator movable section. Is detected, and a timing signal at the time of lens switching is obtained.

Further, by using a light source different from the reproduction laser beam and making it enter the photodetector through the reflecting section attached to the movable section at an intermediate point at the time of lens switching, lens switching is performed. At times, a switching timing signal is obtained in the switching central part.

Further, by providing the identification signal detecting means corresponding to a plurality of lenses, it is possible to determine which lens position is currently present even before the disc is reproduced.

Further, on both sides of the plurality of lenses in the movable section, a reflecting section is provided on the surface constituting the optical system, and the presence or absence of this reflecting section and the reflectance are made different for each lens. By arranging and detecting the amount of light reflected from the reflecting part when the movable part is swung,
It is possible to determine which lens the current position is.

Further, by providing a through hole in the movable portion and detecting the amount of reflected light when the movable portion is swung, it is possible to determine which lens position is currently in position.

Further, by using a light source different from the reproduction laser light, a photodetector is arranged at a fixed portion so that the reflected light can be detected at a position corresponding to each lens, and the light detector is attached to the movable portion. Since the light is incident on the photodetector through the section, it is possible to determine which lens position the current position is.

After performing the lens switching operation,
The lens determination is performed based on the output of the identification signal detector, and if the lens switching is not successful, the pulse width or the drive voltage amplitude value of the kick pulse in the lens switching operation is changed and the lens switching operation is performed again. To work.

Further, the reflected light from the optical disc is received by the photodetector for information reproduction through the through hole provided in the movable portion, and the disc type is recognized by the signal amplitude of the obtained reflected signal. .

The present invention will be described below in detail with reference to the drawings showing the embodiments thereof. Embodiment 1. FIG. 1 is a block diagram of an optical information reproducing apparatus according to a first embodiment of the present invention, in which 11 is a CD objective lens 12 and a DVD objective lens 13 in an optical head fixed, and a focus direction and a track direction. A movable part for moving the movable part 11 in the focus direction, 14 a focus coil for moving the movable part 11 in the focus direction, 15a, 15
Reference numeral b is a tracking coil for moving the movable portion 11 in the track direction, 16 is a mirror for bending the laser light, 17 is a half mirror for separating emitted light and reflected light, 18 is a laser serving as a light source, and 19 is information. , A photodetector for obtaining servo information, 20 an optical system for performing focus and tracking detection, 21 a current-voltage conversion circuit for converting the photocurrent detected by the photodetector 19 into a voltage, and 22 A reproduction signal detection circuit for reproducing information, 23 a tracking error detection circuit for obtaining a track error, 24 a focusing error detection circuit for obtaining a focus error, 25 a disc for determining a plurality of disc types The determination circuit 26 indicates the tracking coil 15 based on the information from the tracking error detection circuit 23. Tracking control circuit for moving the lens switching circuit for performing lens switching according to the type of the disc 27, 28 focus coil 1 based on information from a focusing error detection circuit 24
A focusing control circuit for driving 4 and a drive amplifier 29 for supplying a drive current.

FIG. 2 is a block diagram showing the configuration of a lens switching circuit 27 for switching lenses using the reflecting section provided in the movable section 11. In the figure, 30 is the reflection of parallel laser light from the mirror 16. A reflecting plate constituting a part, 31 is a switching circuit for switching a tracking control signal and a lens switching signal, 32 is a kick pulse generating circuit for giving a driving force in the lens switching direction, and 33 is a braking force at the time of lens switching. To generate a brake pulse, 34 is a polarity switching circuit for switching between a kick pulse and a brake pulse, 35 is an adding amplifier for amplifying the signal from the photodetector 19, and 36 is a signal peak from the adding amplifier. It is a peak detection circuit for detecting.

FIG. 3 is a block diagram showing the configuration of the lens switching circuit 27 in the case where the reflecting plate in FIG. 2 is provided with information on the moving direction. In the figure, 37 is a capacitor for cutting a DC signal, and 38 is a capacitor. Is a zero-crossing comparator for detecting the zero-crossing of the signal, 39 is a pattern matching circuit for judging the information of the digitized signal, 4
Reference numeral 0 is a switching unit determination circuit for detecting the switching timing between the kick pulse and the brake pulse, 41 is a reflector having a bright and dark pattern, 41a is a non-reflective portion, and 41b is a reflection plate.
Is a reflector.

FIG. 4 shows how the lenses are switched in the block diagram of FIG. 3 from the side where the optical system of the movable part is constructed. Reference numeral 42 indicates when the light reflected by the reflector is received by the photodetector. Reproduction signal pattern, 43 is a light spot, 4
Reference numeral 4 is a binarized signal pattern obtained by binarizing the reproduction signal pattern.

In the next-generation optical disk device in which the recording density of the disk is improved, the density of the disk is increased by reducing the thickness of the disk substrate. For example, in a system called a next-generation digital video disc, two discs each having a thickness of 0.6 mm are stuck together, which is about half the thickness of a conventional CD or LD. However, it is impossible for an optical disc with such a thin base thickness and a conventional optical disc to reproduce with the same objective lens due to the relationship of the focal length and the light spot diameter. In order to reproduce the high-density disc, the two optical heads had to be prepared. For example, a conventional optical disc has an objective lens aperture ratio (NA) of 0.4 to 0.
5 is used, and in the next generation type, 0.55 to 0.6 is used.

However, in order to solve such a problem, one movable portion 11 as shown in FIG.
A method of mounting 3 is proposed. Incidentally, although the conventional example has two optical systems for two lenses, even if the number of optical systems is one, if a shaft sliding type actuator is used, the movable part 11 is largely rotated in the tracking direction. This makes it possible to switch only the lens. With such a configuration, a next-generation high-density optical disc with a thin substrate thickness by simply switching lenses without mounting two optical heads or two optical systems in the optical head, and a substrate It has become possible to play back both conventional thick optical discs.

Here, in the optical information reproducing apparatus having the configuration as shown in FIG. 1, first, before the reproducing operation is performed, the disc type is discriminated or the lens switching operation is performed according to the disc type. Will be needed. To determine the disc type, for example, there is a method of making a determination based on information from the reproduction signal, but if the selection of the lens is different, the servo will not be applied, so the servo pull-in operation and the lens switching operation are repeated many times. There was a need. Therefore, when a nonstandard disk is mounted, it is difficult to determine whether the lens is wrongly selected or out of standard, and the determination may be confused.

Therefore, a method of detecting the difference in the disc reflectivity based on the amplitude of the focus error signal, the reproduction signal amplitude at the time of focusing, the tracking error signal amplitude, etc., and recognizing and determining the state of occurrence of the focus error signal. Is taken. In this way, when a focus search is performed using a DVD lens, for example, when a CD disc is searched, no focus point appears in the focus error signal, and in a DVD single-layer disc, there is one error signal with a large amplitude. Occurrence (an error signal having a very small amplitude is also generated on the surface, but this can be ignored), and two error signals having a small amplitude can be observed in the two-layer disc.

The disc discrimination described above is performed by the disc discriminating circuit 25 of FIG. 1 equipped with a signal amplitude hold circuit and a discriminating circuit such as a microcomputer. In this case, the present optical system naturally uses which lens is used. In addition to the necessity of recognizing whether or not there is a difference, when a different lens is used, the lens switching operation must be performed by the lens switching circuit 27.

Further, such a lens switching operation is
This is performed by largely rotating the shaft sliding type actuator in the tracking direction, and since the movable portion of the actuator before the focusing operation is performed has to fall in the head fixed portion by its own weight, the friction It is easily affected, and it is necessary to correct the driving force applied to the tracking actuator in order to switch the lens even if the head posture or temperature changes.

The reaction force due to the wiring of the drive coil 14 drawn from the movable portion of the actuator also varies depending on how the wiring is drawn, so a kick pulse having a predetermined pulse width or voltage level. However, there is a problem that the lens switching is not performed, or conversely, the moving speed is too fast to return to the original lens side due to reaction.

For that purpose, a method is conceivable in which a kick pulse is generated at the current position and the brake pulse is switched between the current position and the target position to stably reach the target position. Such a method is widely used in track jumps and the like, and since the kick pulse and the brake pulse are switched at the midpoint, there is an advantage that the operation is always stable even if there is friction or reaction force. It was However, in the lens switching operation in the actuator equipped with the two lenses described above, there is a problem that the lens switching cannot be performed stably because the midpoint cannot be detected.

Therefore, the midpoint is optically detected by the method shown in FIG. In this system, a reflector 30 is attached between two lenses 12 and 13 on the side where the optical system of the movable portion 11 of the actuator is formed, and the reflector 3 is formed by a laser beam used for reproducing information.
Since the reflected light by 0 is detected and a normal signal reproducing laser and a detector are used for the detection optical system, there is an advantage that the optical system is not complicated. In this method, the laser light used for normal reproduction when the lens is switched is the reflection plate 3 described above.
When the light passes through 0, reflected light is obtained from the photodetector 19, so the output from the photodetector 19 is amplified by the summing amplifier 35, and the peak detection circuit 36 extracts the peak of the signal. The passing timing of 13 intermediate positions can be obtained. Further, at this timing, the kick pulse and the brake pulse are switched to the polarity switching circuit 34.
By switching with, stable lens switching operation is realized.

According to this structure, the width of the kick pulse can be reliably generated up to the intermediate point of the lens switching operation, as compared with the method of applying a pulse of a constant width, so that switching mistakes can be made even with respect to friction and reaction force. Less. For example, when friction or the like is large, the time required to reach the intermediate point is long, and as a result, the kick pulse width is large and a large driving force can be automatically applied. Here, the above-described reflector 30 is the movable portion 1 of the actuator.
1 may be vapor-deposited with aluminum, or a reflective tape or a reflective mirror may be attached. Moreover, in this method, since the parallel laser light in the optical system is used,
There is an advantage that the same detection characteristic can be obtained regardless of the height of the movable portion 11 of the actuator.

By the above-mentioned method, it becomes possible to detect the middle point at the time of lens switching, but if it can be detected from which side of the lens and in which direction the lens is moving, lens switching is performed by external force such as vibration of the device. Can not be done well,
These states can be discriminated even when the lens is returned on the way or when the lens is switched to another lens due to the servo being lost during the normal reproduction. The detection of the moving direction as described above can be realized by arranging a bright and dark pattern on the reflection plate 41 as shown in FIG. in this case,
When the movable portion 11 is switched to another lens, the parallel laser light scans the reflecting portion 41a and the non-reflecting portion 41b as the reflecting portion 41 passes, so the output of the addition amplifier 35 obtained at this time is zero crossed. The direction is discriminated by pattern matching the binarized value by the comparator 38. In the pattern matching circuit 39, a signal pattern 44 obtained by binarizing the reproduction signal pattern 42 as shown in FIG.
The determination can be made by comparing the high-level pattern interval D obtained first in the figure with the next high-level pattern interval C or the last high-level pattern interval A, for example. In the case of the pattern of FIG. 4, if the first high level width> the next high level width, D
The objective lens 13 for VD moves to the objective lens 12 for CD, and if the first high level width <the next high level width, it means that the objective lens 12 for CD moves to the objective lens 13 for DVD.

Embodiment 2. Although the above-mentioned timing signal generating means has the movable portion 11 provided with the reflecting portion 30 or 41, the same effect can be obtained by using the through hole provided in the movable portion 11. FIG. 5 is a block diagram showing a method of obtaining a timing signal at the time of lens switching from the reflected light from the optical disc 50 through the through hole. In the figure, 50 is an optical disc and 51 is a movable part 11.
Is a through hole provided between the two lenses 12 and 13.

FIG. 6 is a block diagram showing a method of obtaining a timing signal at the time of lens switching from the reflecting portion of the loading mechanism through the through hole. In the figure, 52 is a loading mechanism and 53 is a loading mechanism 52. It is a reflector.

Further, FIG. 7 is a block diagram showing a method of obtaining a timing signal at the time of lens switching by receiving the light passing through the through hole by the light receiving portion of the loading mechanism. In the figure, 55 is attached to the loading mechanism 52. The light detector 56 is an amplifier for amplifying the detection information from the light detector 55.

FIG. 8 is a block diagram showing a method of obtaining a timing signal at the time of lens switching using the through hole by a light emitting section different from the laser beam used for reproducing information. It is a department.

Further, FIG. 9 is a block diagram showing a method of providing a plurality of through holes 51 and obtaining a timing signal at the time of lens switching, in which the moving direction can be detected by the difference in size of the through holes 51a and 51b.

In the first embodiment, the middle point at the time of lens switching is detected by attaching the reflecting plate. However, as a method of omitting the attaching of the reflecting plate, FIG.
A method of providing the through hole 51 as shown in FIG. This method is a method of obtaining a timing signal through the through hole 51 by using the optical disc 50 instead of the reflection plate. In this case, the amount of reflected light changes as the movable portion 11 of the actuator rotates. Particularly, when the member of the movable portion 11 is irradiated with the parallel laser light, almost no reflection occurs. Further, even when the light passes through the objective lenses 12 and 13, in the case of defocusing in which the focus servo is not operating, the ratio of the light passing through the lens to the optical disc 50 to be reflected and returned is considerably small due to eclipse. become.

On the other hand, the optical disk 50 passes through the through hole 51.
In the case where the light is reflected by, the parallel laser light is reflected as it is, so that a considerable amount of light is returned in a condensed form on the photodetector 55. Since the optical disc 50 may be distorted due to deformation or the like, it is possible to reduce the influence of the deformation by rotating the optical disc 50. Further, even in this case, as in the first embodiment, since the parallel laser light in the optical system is used, the timing signal can be obtained regardless of the height of the actuator in the focus direction. Also in this method, the detection signal is processed by detecting the midpoint by the peak detection circuit 36 and switching the polarities of the kick pulse and the brake pulse by the lens switching circuit 34, as in the first embodiment.

Further, as described above, when the optical disk 50 is used as the reflection target, there is a problem that the reflection does not occur in the initial state where the disk is not loaded. Therefore, as shown in FIG. 6, by mounting the reflection plate 53 on the movable portion 11 of the actuator in the loading mechanism 52, it becomes possible to detect the timing signal even when the disc is not inserted. Further, the reflectance of the reflector 53 and the optical disk 5
If the reflectances of 0 are set differently, it is possible to confirm whether or not the disc is inserted. As a result, the disk detection sensor, which is conventionally installed exclusively, becomes unnecessary. If the amount of reflected light is detected while driving the optical head in the feed direction, it is possible to determine not only the presence or absence of the disc but also the disc diameter difference.

When the difference in reflectance between the reflector 53 in FIG. 6 and the optical disk 50 cannot be clarified, the loading mechanism 52 receives parallel light directly instead of the reflector 53 as shown in FIG. A method of providing the photodetector 55 can be considered. In this case, the passing state of the parallel laser light through the through hole 51 can be detected in the state where the optical disc 50 is not mounted, and thus the timing signal similar to that in FIG. 6 can be obtained. In this case, the photodetector 55 must be long in the feed direction so that it can be detected even if the optical head moves in the feed direction. However, if the position for switching the lens is determined to be, for example, the inner circumference of the disc, the photodetector 55 long in the feeding direction as shown in FIG. 7 becomes unnecessary.

Further, as shown in FIGS. 5 to 7,
A timing signal can be obtained by receiving the light from the dedicated light emitting section 57 by the photodetector 55 shown in FIG. 7 without using the parallel laser light used for reproducing information in the optical head. Even in this case, the photodetector 55 must be configured to be long in the feed direction so that it can be detected even if the optical head moves in the feed direction. However, if the position for switching the lens is determined to be, for example, the inner circumference of the disk, the photodetector 55 long in the feeding direction as shown in FIG. 8 becomes unnecessary.
Further, it is appropriate that the light emitting portion 57 is generally provided in a fixed portion inside the optical head, but the light emitting portion 57 is attached to a deck mechanism for fixing the optical head and provided in the optical head fixing portion. Light may be received through the hole and the through hole 51 of the movable portion 11. In this case as well, the position of the optical head for switching lenses must be determined in advance, but there is an advantage that not only the presence or absence of an optical disk but also the initial position of the optical head in the feeding direction can be detected at the same time.

The method using the through hole described above is only for obtaining the timing signal at the time of lens switching, but the method using such a through hole also has the following effects as shown in FIG. 3 in the first embodiment. It is possible to determine the moving direction when the lens is switched. For example, as shown in FIG. 9, a plurality of through holes 51 are formed and the through holes 51a and 52b are arranged so that the widths thereof are different, or the arrangement of the through holes is not uniform in the lens switching direction. By doing so, it is possible to equivalently create a structure such as the light-dark pattern of FIG. In this case, the light received from the photodetector 19 is detected by the direction determination circuit 58.
And the peak detection circuit 36 detects the switching timing of the kick pulse and the brake pulse,
The polarity switching circuit 34 switches the polarity. For example, the widths of the through holes 51a and 51b in the figure are 51a> 51b.
If the pulse width and the next pulse width of the first received light signal received by the photodetector 19 are such that the first pulse width> the next pulse width, the CD objective lens 1
2 to the objective lens 13 side for DVD, and vice versa
It can be recognized that the lens is moving from the VD objective lens 13 to the CD objective lens 12 side.

Embodiment 3 In the first and second embodiments, the timing signal is detected by using the laser beam used for reproducing information, but it can be detected by completely different means. For example, FIG. 10 is a block diagram showing a method of detecting a back electromotive force generated in the tracking actuator coils 15a and 15b and detecting a switching timing from the back electromotive force. In the figure, 59 flows in the actuator coils 15a and 15b. A current detection resistor for detecting a current, 60 is a current detection amplifier for extracting the current flowing in the current detection resistor 59 as a voltage, and 61 is a drive current amount estimated from the voltage applied to the actuator and an actual drive current. The counter electromotive force detection amplifier for comparing the amounts, 62 is a gain adjustment amplifier for converting the drive voltage into the estimated current amount, 63 is a capacitor for cutting the DC component for detecting the zero cross of the switching timing, Is.

FIG. 11 is a block diagram showing a method of superimposing an alternating current on the tracking actuator coil 15 at the same time as a driving kick pulse or a braking pulse and detecting it by an external coil. In the figure, 64 is an optical head fixed. A magnet for tracking fixed to the portion, 65 is a detection coil for detecting the AC magnetic field from the tracking actuator coil 15, 66 is an amplifier for amplifying the AC magnetic field detected by the detection coil 65, and 67 is a reproducing AC magnetic field. A detection circuit for detecting the amplitude of the signal envelope, 68 an oscillator for supplying an AC signal to the tracking actuator coil 15, 69 an amplifier for determining the amplitude of the AC current, and 70 adding the AC signal to the drive signal. It is an adder for doing.

Further, FIG. 12 is a block diagram showing a method of detecting a timing signal by reflection from a light different from the laser light for reproducing information by the bending mirror mounted on the movable portion 11. , 71 is a folding mirror, 72 is a DVD photodetector, 73 is a lens switching photodetector, and 74 is a CD photodetector.

FIG. 13 is a diagram showing a system having a light receiving portion on the side opposite to the side on which the objective lens is mounted in the movable portion 11. In the figure, 75 is a DVD photodetector and 76 is a lens. A switching photodetector, 77 is a CD photodetector.

FIG. 14 is a diagram showing a method of applying a kick pulse and a brake pulse in the case where the tracking magnet has a structure like 64a, 64b shown in the drawing.

In the first and second embodiments, the timing signal is detected by the reflector and the through hole by using the optical system and the detector used for reproducing the information, but the actuator is not modified for the timing detection. However, there is a method that can be detected. For example, as shown in FIG. 10, it is a method of detecting the counter electromotive force applied to the tracking actuator coils 15a and 15b, and can be realized only by providing the current detection resistor 59 and the counter electromotive force detection circuit. Therefore,
The actuator mechanism section does not need to be specially worked.
In FIG. 10, the counter electromotive force is compared by the counter electromotive force detecting amplifier 61 with the value obtained by extracting the current flowing through the current detecting resistor 59 by the current detecting amplifier 60 and the value obtained by extracting the drive voltage by the gain adjusting amplifier 62. It is obtained by This is because the detected drive current deviates from the current value determined by the drive voltage and the coil resistance due to the influence of the counter electromotive force generated when the tracking actuator coils 15a and 15b pass through the magnetic circuit.

Further, since the actuator in the figure constitutes two magnetic circuits for DVD and CD, the signal obtained by cutting the direct current component by the capacitor 63 becomes as shown in the figure.
This is because by detecting the zero cross of the signal, the switching timing which is the middle of the two lens positions can be extracted. However, in this method, although the actuator does not need to be modified, the coil resistance fluctuates due to temperature changes and the magnetic field strength of the magnetic circuit fluctuates, so that the accuracy as shown in the first and second embodiments is improved. There is a problem that it is difficult to detect high.

As a method using the above-mentioned change in magnetic field, a method in which an alternating magnetic field is further generated when a kick pulse or a brake pulse is applied and the magnetic field is detected by an external detection coil can be considered. In this method, as shown in FIG. 11, the AC signal of the oscillator 68 is superimposed on the drive signal of the actuator. The frequency at this time must be set to a high frequency that does not cause a mechanical response of the actuator and lower than the frequency that is attenuated by the inductance of the actuator coil 15. Also, the amplifier 69
After setting the amplitude to a predetermined value, the adder 70 superimposes it.

On the other hand, the detection is performed by the actuator coil 15
The AC magnetic field generated by the
The detection coil 65 provided at an intermediate point of the objective lens 13 receives the signal, the amplifier 66 amplifies the received signal, and the detection circuit 67 detects the amplitude of the received signal. The received signal amplitude thus detected is subjected to timing signal detection and switching between kick pulse and brake pulse by a method similar to that shown in FIG. However, in this method, a dedicated AC magnetic field is used as compared with the method using the counter electromotive force in FIG. 10, so that the detection accuracy becomes high, but the mounting accuracy of the detection coil 65 must be ensured. There is a problem.

Further, as shown in FIG. 12, there is also a method of detecting with a bending mirror 71 and a dedicated light emitting section 57.
In this case, by disposing a plurality of detectors 72 to 74, it is possible to detect the position of the objective lens 12 for CD and the position of the objective lens 13 for DVD in addition to the timing of lens switching. However, since the bending mirror 71 is mounted on the movable part, the weight of the movable part is slightly increased, and when the detectors 72 to 74 are attached to the optical head fixed part, a timing signal is obtained regardless of the focus position of the actuator. In addition, it is necessary to devise the shape of the detectors 72 to 74 to be long in the focus direction.
However, the objective lens 12 for CD and the objective lens 1 for DVD
Since the lens position of No. 3 can also be detected, it becomes possible to perform lens determination described later, perform damping during control operation by differentiating the actuator movable portion position information, and detect the tracking sensor offset by detecting the lens shift amount. .

Further, even if the folding mirror 71 is not used, as shown in FIG.
Detector 75 in the direction opposite to the position where 2 and 13 are mounted
It is also possible to obtain the same effect as that of FIG. 12 by attaching ~ 77. However, in this case, the movable part 1
Since the detectors 75 to 77 are mounted on the first unit, there arises a problem that the number of wires from the movable section 11 increases, and it is necessary to consider the reaction force due to the wires.

The actual application of the kick pulse or the brake pulse in the timing signal detection as described above is performed when the magnetic circuit of the actuator is arranged like the tracking magnets 64a and 64b of FIG.
Represented as pulses 79-82 in the middle. This is because the polarity of the magnetic circuit is reversed with the movement of the tracking actuator coil 15, and for example, the magnetic flux of the tracking magnet 64a is generated from N to S on the coil 15 side in the figure, while the tracking magnet is generated. This is because the direction of the magnetic field that wraps around the coil 15 of 64a toward the back side is opposite. In this case, it is necessary to apply reverse pulses before and after the polarity reversal, and the kick pulse must be applied as 79, 80 in the figure and the brake pulse as 81, 82 in the figure. I won't. This is the same in the first and second embodiments.

Fourth Embodiment Although the method for generating the switching timing signal at the time of lens switching has been described in the first to third embodiments, the measures including the function of confirming the current position of the lens will be described below. Needless to say, in order to reproduce an optical disc having a plurality of types of physical characteristics, it is necessary to determine the type of the disc before reproducing. This is because if the disc type cannot be determined, it will not be possible to switch to a lens that is compatible with the disc, and as a result, focus and tracking operations will also become defective. Such a disc type determination can be obtained by using a specific lens and checking the occurrence status of an error signal or a sum signal when the focus search is performed on the specific lens. Therefore, the current objective lens can be reproduced without reproducing the signal. How to determine which is very important.

FIG. 15 is a block diagram showing a lens switching method of the fourth embodiment having a lens position fixing function using three reflecting portions 83 to 85 provided on both sides of the objective lens. Is the objective lens 12 for CD
, 84 is a reflection portion provided outside the DVD objective lens 13, 85 is a reflection portion provided between the CD objective lens 12 and the DVD objective lens 13, and 86 is a detection portion. A level determination circuit for determining the level of the reflected light amount, and a switching determination circuit 87 for detecting the switching timing. 16 is a diagram showing the movement of the spot of the parallel laser light on the movable part 11 of FIG.

FIG. 17 is a block diagram showing a method for providing a lens position fixing function in the case where one reflecting portion is provided between the objective lenses. In the figure, 88 binarizes the detected reflected light amount. Is a comparator for determining the current position of the lens, 89 is a lens position determination circuit for determining the current position of the lens, 90 is a horizontal shake signal generating circuit for swinging the movable portion 11 left and right, and 91 is a movable portion 1 on the side of the CD objective lens.
Output of comparator 88 when 1 is swung left and right, 92
Is the output of the comparator 88 when the movable part 11 is swung left and right on the side of the objective lens for DVD, 93 is the horizontal shake signal waveform for shaking the movable part 11 left and right, and 94 is the horizontal shake signal driven with a predetermined amplitude. It is an addition ratio setting amplifier for making it.

Further, FIG. 18 shows a structure in which a reflecting mirror between the objective lenses 12 and 13 can change the light amount in the lens switching direction. In the drawing, 95 is a reflecting portion arranged between the lenses, and 96 is a reflecting portion. Is a reflecting portion having a low reflectance arranged outside the objective lens 13 for DVD, and 97 is a reflecting plate 9.
A switching determination unit for determining the switching timing according to 5 and a level increase / decrease determination circuit 98 for determining the lens movement direction based on the light receiving level from the reflector.

Further, FIG. 19 shows a different pattern from that of FIG. 18 in which the reflection plate in the center of the lens gradually increases and decreases in the moving direction. In FIG. 19, 99 moves the lens based on the amount of reflected light received from the reflection plate 100. It is a level increase / decrease determination circuit for determining the direction.

Further, FIG. 20 is a block diagram for determining the lens position using the through hole 51 in the movable portion 11 and at the same time determining the disc type from the reflectance of the disc.

In addition, FIG. 21 shows a CD from the confirmation of the lens position.
FIG. 22 is a flowchart showing the operation of the optical information reproducing apparatus until the signal reproduction of the disc, and FIG. 22 is a flowchart showing the operation of the optical disc apparatus from the determination of the lens to the signal reproduction of the DVD disc.

FIG. 23 is a flowchart showing the operation of the optical disk device when the type of the disk is determined using the through hole, FIG. 24 is a flowchart showing the lens confirmation work and the lens switching operation, and FIG. 25 is the lens switching operation. FIG. 26 is a flowchart for learning the pulse width when repeating, FIG.
FIG. 27 is a flowchart showing the lens switching operation to the side lens, and FIG. 27 is a flowchart showing the lens switching operation from the DVD lens side to the CD lens side.

Next, the operation of each embodiment will be described. In a system equipped with a plurality of objective lenses as described in the first to third embodiments, which lens side is currently at the stage before performing the reproducing operation, at the time of recovery from the servo loss, etc. Awareness is very important. For example, in the case of performing a reproducing operation when a CD disc is loaded, as shown in the flowchart of FIG.
After the objective lens for DVD or DVD is determined, the disc type is determined by the focus search, and then the lens switching operation and the like are performed.

The same applies to the case of reproducing a DVD disc, and as shown in the flowchart of FIG. 22, the operation starts in the objective lens position determination, then disc determination, and lens switching. This is because if the objective lens is not fixed, it is not possible to determine which disk is used even by observing the error signal and the reproduction signal amplitude during focus search. If the type of the objective lens is fixed, the CD disc or DV
This is because it can be determined whether the disc is a D disc or a DVD with a low reflectance.

Therefore, as a method using the reflecting plate shown in the first embodiment, a reflecting plate is added outside the objective lens as shown in FIG. There is a method of determining the lens position.
In this method, as shown in the flowchart of FIG.
First, the movable part 11 is moved in either of the tracking directions. In particular, it is not possible to determine whether the movable part 11 should be moved clockwise or counterclockwise because it is not known which side it is initially. However, as shown in FIG. 15, when the CD objective lens 12 is used, for example, the reflecting portions 83 and 8 having high reflectance are provided.
Since 5a is on both sides, the photodetector 1 can be moved to either side.
A signal corresponding to a large amount of reflected light is obtained from 9.

On the other hand, in the case of being on the DVD side, as shown in FIG.
As shown in FIG. 6, since the reflecting portions 84 and 85b having a low reflectance are provided on both sides of the objective lens 13 for DVD, even in this case, if the movable portion 11 is moved to either side, the light receiving from the reflecting plate having a low reflectance is received. By detecting, the level determination circuit 86 can determine which lens is used from the above difference in amplitude. Further, since the reflection plate 85 in the center of the two objective lenses 12 and 13 is configured so that the reflectance changes midway, the timing signal at the time of lens switching can also be detected by the switching determination unit 87. . In this case, the reflection portion having a low reflectance can be realized in a pseudo manner by forming a non-reflection portion (for example, a black print pattern) sufficiently smaller than the light spot size on the reflection surface as shown in FIG. is there.

The above lens position determination operation is performed by, for example, DV
When the lens is switched to the D objective lens 13 side, the process is performed as shown in the flowchart of FIG. In this case, first, the lens position is determined by swinging the movable portion 11 to the left and right, and then the lens switching operation is performed by capturing the reflectance change of the reflecting portion 85 between the two lenses.
After switching, the lens position determination operation is performed again. Also, C
Even when the lens is switched to the D objective lens 12 side, the switching operation is performed in the same manner as in the case of FIG. 26 as in the flowchart shown in FIG.

Further, as shown in FIG. 16, the objective lens 1
The objective lens 1 can be provided without providing reflection parts on both sides of
It is also possible to determine the lens position only from the reflection part between 2 and 13. In this method, first, as shown in FIG. 17, the movable portion 11 is moved to the left and right by the horizontal shake signal generator 90. At this time, a signal obtained by binarizing the amount of received light obtained from the reflection unit 30 by the comparator 88 gives a signal like 91 when it is on the side of the CD objective lens 12, and DV
When it is on the D objective lens 13 side, a signal such as 92 is obtained. Such signals 91 and 92 are transmitted to the movable portion 11
Comparing it with the horizontal shake signal 93 that is moving, it can be seen that the phase of the horizontal shake signal 93 appears in different phases on the DVD objective lens 13 side and the CD objective lens 12 side. This is because the reflection unit 30 is on the right side when viewed from the CD objective lens 12 in the drawing and on the left side when viewed from the DVD objective lens 13, and therefore has a different phase with respect to the drive signal. This phase difference is determined by the lens determination circuit 8
By detecting at 9, the determination result of the lens position can be obtained.

Such a lens determination method is operated in combination with the lens switching operation according to the flowchart shown in FIG. In FIG. 24, for example, a DVD
This shows a method for reproducing a disc. First, the objective lens is moved, and then the lens position is determined by comparing the amount of light received from the reflection section 30 (sum signal in the figure) and the drive signal, and then the CD side. In the case of 1, the lens switching operation is performed, the reproduction is started after the determination is performed again. While such a method requires the above-mentioned phase comparison circuit, the reflection part has
There are good advantages here.

Further, as shown in FIG. 18, by configuring the reflection pattern of the central reflection portion 95 to be asymmetric with respect to the light spot scanning direction, the same effect as in FIG. 16 can be obtained. is there. In this case, the reflection unit 95 has an asymmetrical structure as shown in the drawing, and the level increase / decrease determination circuit 98 determines whether the change in the reflected light amount when passing through the reflection unit 95 is in the decreasing direction or the increasing direction. It is obtained by judging. Further, since the reflection part 95 has a configuration in which the same pattern is repeated twice at the central part, after switching the DC component of the received signal by the capacitor 37, the zero cross comparator 38 detects the zero cross of the signal to switch the lens. You can get the timing.

Further, the reflection pattern of the reflection part 100 provided in the central part of the two objective lenses 12 and 13 can be constructed as shown in FIG. In this case, the amount of light received from the reflecting section 100 is only two, that is, whether the amount of light received from the reflecting section 100 is decreasing or increasing with respect to one moving direction. It is possible. However, in the case of FIG.
Since there is no reflected light amount change portion for the switching timing in the center of, the signal amplitude in the central portion of the reflecting portion 100 is set in advance, and this is set to the comparator 8
It is necessary to obtain the switching timing by slicing at 8. In the systems of FIGS. 18 and 19, the reflecting portions 83, 96, and 94 having different reflectances are prepared outside the objective lenses 12 and 13, so that the lens position can be naturally determined.

It is also possible to determine the lens position using the through hole without using the above-mentioned reflecting portion. In this case, the through hole 51 is prepared in the movable portion 11 as shown in FIG. 20, and the movable portion 11 is shaken by the horizontal shake signal generator 90, so that it is possible to make a determination by the same principle as in FIG. is there. In FIG. 20, the photodetector 55 is mounted on the loading mechanism 52 to obtain a signal from the light emitting section 57, but a through hole is formed between the objective lenses 12 and 13, and a parallel laser beam used for information reproduction is formed. The same effect can be obtained by using.

Further, it is obvious that the reflected light from the disk may be received by the photodetector for information reproduction as shown in FIG. In the method using such a through hole, since the reflected light from the disc can be received, it is possible to detect the reflectance of the disc and determine the type of the disc having the different reflectance. FIG. 22 is a flow chart showing this disc type determination method. Depending on whether the disc reflected light amount from the through hole is a predetermined amount or more,
For example, it is possible to determine whether the disc is a dual-layer disc having a low reflectance.

A method is conceivable in which only the lens position determining operation as described above is used and the lens switching timing is not used. As shown in the flow chart of FIG. 25, this method first determines the lens position, then applies a kick pulse having a predetermined width and amplitude when the lens is not a predetermined lens, and again after switching the lens. Determine the lens position. At this time, if the lens switching is not successful, increase the kick pulse width or height,
The lens switching operation is performed again. If lens switching cannot be performed successfully even after repeating this, the kick pulse width and height are made smaller than at the beginning to operate. In this way, there is also a method of learning the width and height of the kick pulse while repeating the lens switching operation several times to search for the optimum kick pulse. However, although such a method does not require a lens switching circuit, there is a problem that it takes time to complete the search.

[0106]

In the optical information reproducing apparatus according to the present invention, since the timing signal at the time of lens switching of the optical head equipped with the plurality of objective lenses is obtained, the switching operation is normally performed at the lens switching. It becomes possible to confirm whether or not it has been performed, and it is possible to change the width of the applied pulse required for lens switching according to changes in actuator axial friction, posture, etc., so stable switching operation is possible. The effect that can be realized is obtained.

Further, since the operation at the time of lens switching is configured to be performed by the kick pulse and the brake pulse, and the switching of the above two pulses is performed by the timing signal, the operation of the movable portion at the time of lens switching is performed. It became smooth and the switching operation no longer failed due to the influence of friction.

Further, since the parallel laser light in the optical system is reflected by the reflecting portion provided in the movable portion to generate the timing signal, even if the movable portion moves in the focus direction, an accurate detection signal is obtained. Moreover, since the laser beam for information reproduction and the detector are used, an accurate timing signal can be obtained with an extremely simple configuration.

Further, since the reflecting portion is provided with the light and dark portions, not only the switching timing but also the moving direction of the movable portion can be detected, and the state is maintained even when the driving force is insufficient or the driving force is too strong at the time of switching. Can be observed and the switching operation can be redone again. Also,
As a result, when the current lens position is known, it is possible to determine which lens the lens has moved to, including the case where the lens has failed and returned.

Further, since the timing signal is obtained by the light passing through the through hole provided in the movable portion, it is not necessary to provide the actuator with the reflecting portion, and the size of the disk can be reduced by moving the optical head in the feeding direction. It is also possible to detect the initial position of the optical head.

Furthermore, since a plurality of through-holes having different widths are provided in the movable part, the same effect as providing the light-dark part in the reflecting part can be obtained.

Further, since the counter electromotive force generated in the actuator tracking coil is detected to detect the timing, it is possible to perform the accurate lens switching operation without any special work on the movable portion. It was

Furthermore, since an AC current is generated in the actuator tracking coil and is received by the external detection coil, it is possible to perform the special work on the movable part without any special work.
A more accurate timing signal can be obtained as compared with the method using the counter electromotive force.

Since the timing signal is detected by using a light source different from the light source used for reproducing information, the lens shift amount at each lens position can be accurately detected in addition to the timing signal, and the tracking sensor offset can be reduced. Moreover, since the damping of the actuator can be performed, more accurate track following operation can be realized.

Further, since the identification signal detecting means for identifying the position of the objective lens is provided, it is possible to recognize which objective lens is the current lens without reproducing the signal from the disc.
Since the lens switching operation can be performed quickly, as a result, the playback waiting time of the disk can be shortened, and the recovery from the servo-off state can be performed quickly.

Further, since the reflecting portions having different reflectances are provided on both sides of the objective lens, the lens position can be determined by the laser beam used for information reproduction and the detector.

Further, since the lens position is determined by the reflected light from the disk that has passed through the through hole when the movable part is moved to the left and right, the lens position is not required to be provided on both sides of the objective lens. You can now determine the position.

Further, by performing lens position determination using a light source different from the light source used for information reproduction, besides the lens position determination, the lens shift amount at each lens position can be accurately detected, and the tracking sensor offset Since the reduction and the damping of the actuator can be performed, more accurate track following operation can be performed.

Further, since the reflecting portion is provided between the two objective lenses and the lens position is determined by the reflected light when the movable portion is moved to the left or right, the reflecting portions and the like are not attached to both sides of the objective lens. Even now, accurate track following operation can be performed.

Further, since the disc type is discriminated after the position of the objective lens is discriminated, it is possible to discriminate the disc type of the present disc without reproducing the signal of the disc, and the disc discriminating operation can be carried out quickly. As a result, the waiting time for playing the disc has been shortened.

Further, since the malfunction of the lens switching operation is identified based on the result of the position determination of the objective lens and the kick pulse width is changed to restart the operation, the timing detection at the time of switching the objective lens becomes unnecessary, and the switching operation is performed. The circuit was simplified.

Further, the amount of light reflected from the disc can be detected through the through hole provided in the movable portion, and the disc type can be discriminated from the disc reflectance difference.

[Brief description of drawings]

FIG. 1 is a block diagram showing a control system in an optical information reproducing device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a lens switching system using the reflection unit according to the first embodiment.

FIG. 3 is a block diagram showing a lens switching system in which bright and dark are provided in a reflecting portion according to the first embodiment.

FIG. 4 is a diagram showing a change in reflected light of the light spot in FIG.

FIG. 5 is a block diagram showing a lens switching system using a through hole in the optical information reproducing apparatus according to the second embodiment of the present invention.

FIG. 6 is a block diagram showing a lens switching method using a through hole and a reflecting section provided in a loading mechanism according to the second embodiment.

FIG. 7 is a block diagram showing a lens switching system using a through hole of the second embodiment and a detector provided in a loading mechanism.

FIG. 8 is a block diagram showing a lens switching method using a dedicated light emitting unit, a through hole, and a detector provided in a loading mechanism according to the second embodiment.

FIG. 9 is a block diagram showing a lens switching system using a plurality of through holes according to the second embodiment.

FIG. 10 is a block diagram showing a lens switching system using a counter electromotive force in the optical information reproducing apparatus according to the third embodiment of the present invention.

FIG. 11 is a block diagram showing a lens switching system using an AC magnetic field according to a third embodiment.

FIG. 12 is a block diagram showing a lens switching system using a dedicated optical position detector according to the third embodiment.

FIG. 13 is a block diagram showing a lens switching system using a dedicated optical position detector attached to a movable part according to a third embodiment.

14 is a diagram showing applied waveforms of a kick pulse and a brake pulse in FIG.

FIG. 15 is a block diagram showing a lens position determination method using a reflecting portion outside a lens in an optical information reproducing device according to a fourth embodiment of the present invention.

FIG. 16 is a diagram showing the movement of the light spot in FIG. 15 of the fourth embodiment.

FIG. 17 is a block diagram showing a lens position determination method using a reflector provided between objective lenses according to a fourth embodiment.

FIG. 18 is a block diagram showing a lens position determination method using a reflecting portion outside the objective lens and a reflecting portion having an asymmetrical dark / light portion whose reflectance is switched in the middle provided between the objective lenses according to the fourth embodiment. Is.

FIG. 19 is a block diagram showing a lens position determination method using a reflecting portion outside the objective lens and a reflecting portion having an asymmetrical dark / dark portion between the objective lenses according to the fourth embodiment.

FIG. 20 is a block diagram showing a lens position determination method using a through hole according to a fourth embodiment.

FIG. 21 is a flowchart when reproducing a CD disc according to the fourth embodiment.

FIG. 22 is a flowchart when reproducing a DVD disc according to the fourth embodiment.

FIG. 23 is a flowchart for disc determination according to the fourth embodiment.

FIG. 24 is a flow chart when determining an objective lens according to the fourth embodiment.

FIG. 25 is a flowchart of kick pulse learning when switching the objective lens according to the fourth embodiment.

FIG. 26 is a flowchart of the lens kick to the DVD side according to the fourth embodiment.

FIG. 27 is a flowchart of the lens kick to the CD side according to the fourth embodiment.

FIG. 28 is a perspective view showing an optical head equipped with a plurality of lenses of a conventional optical information reproducing apparatus.

[Explanation of symbols]

11 movable part, 12 objective lens for CD, 13 DVD
Objective lens, 14 focus actuator coil,
15 tracking actuator coil, 16 mirror, 17 half mirror, 18 laser, 19, 72,
73, 74, 75, 76, 77 photodetector, 20 optical system, 21 current-voltage conversion circuit, 22 reproduction signal detection circuit, 23 tracking error detection circuit, 24 focusing error detection circuit, 25 disc discrimination circuit, 2
6 tracking control circuit, 27 lens switching circuit, 28 focusing control circuit, 29 drive amplifier, 30, 41, 53, 83, 65, 84, 85, 9
5,96,100 reflector, 31 switching circuit, 32
Kick pulse generation circuit, 33 brake pulse generation circuit, 34 polarity switching circuit, 35, 56, 60, 6
1,66 amplifier, 36 peak detection circuit, 38,88
Comparator, 39 pattern matching circuit, 40
Switching determination circuit, 52 loading mechanism, 58
Direction determination circuit, 64 tracking magnet, 67
Detection circuit, 68 oscillator, 86 level determination circuit, 87
Switching brake pulse determination circuit, 89 lens position determination circuit, 90 left-right direction shake signal generator, 97 switching unit determination circuit, 98 level increase / decrease determination circuit.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kimihide Nakatsu 2-3-3 Marunouchi, Chiyoda-ku, Tokyo Sanryo Electric Co., Ltd. (72) Eiji Yokoyama 2-3-2 Marunouchi, Chiyoda-ku, Tokyo 3-3 In Ryo Electric Co., Ltd. (72) Inventor Keiji Nakamura 2-3-3 Marunouchi, Chiyoda-ku, Tokyo Sanryo Electric Co., Ltd.

Claims (17)

[Claims] 1. A plurality of objective lenses are provided for an information reproducing optical system by having a movable part on which a plurality of objective lenses having different numerical apertures are mounted and reproducing the optical disc having different physical characteristics. In the optical information reproducing device that selects and uses a disc suitable for the physical characteristics of the disc from among the above, it is provided with a timing signal generator that generates a predetermined timing signal when the plurality of objective lenses are switched. Characteristic optical information reproducing device. 2. The different objective lenses are switched by continuously applying a drive pulse and a brake pulse to an actuator that drives the movable portion in the tracking direction, and at the same time, output the timing signal generator. The optical information reproducing apparatus according to claim 1, wherein the drive pulse is switched to the brake pulse based on the above. 3. The timing signal generator comprises one or a plurality of reflectors attached to a surface on a side where an optical system between a plurality of objective lenses mounted on the movable portion is formed. The detection of the timing signal is performed by detecting a reflected light from the reflecting portion of the laser light for reproducing information by a photodetector. The optical information reproducing device according to item 1. 4. The bright and dark portions having different reflectances are provided in the reflecting portion, and the light and dark portions are arranged differently for each of the plurality of objective lenses, or asymmetric with respect to the moving direction of the objective lens. According to the third aspect of the invention, the switching direction and the destination lens can be specified when the objective lens is switched.
An optical information reproducing device according to the item. 5. The timing signal detector is constituted by a through hole provided between a plurality of objective lenses in the movable part, and the detection of the timing signal is for reproducing information emitted from an optical system. A light beam is reflected through a through hole through a reflection surface attached to an optical disk or a disk mounting mechanism above the optical head, and the reflected light of the light beam is detected. 2. An optical information reproducing apparatus according to item 1 above. 6. A predetermined objective lens is formed by forming a plurality of the through holes between a plurality of objective lenses and arranging the plurality of through holes so that the widths of the holes in the track direction are different from each other. 6. The optical information reproducing apparatus according to claim 5, wherein the switching direction and the destination lens are specified at the time of switching. 7. A tracking actuator coil, wherein the timing signal detector drives the movable portion mounted on the movable portion in a track direction, an actuator driving magnet fixed to the optical head, and the coil. The optical information reproducing apparatus according to claim 1, wherein the optical information reproducing apparatus comprises a back electromotive force detection circuit for detecting the back electromotive force. 8. The timing signal detector applies a tracking actuator coil for driving the movable portion mounted on the movable portion in a track direction, and an alternating current to the tracking actuator coil to generate an alternating magnetic field. An alternating current magnetic field detecting means fixed to the optical head and configured to detect an alternating magnetic field due to the alternating current generated from the tracking actuator coil, which is fixed to the optical head. The optical information reproducing device according to item 1. 9. The timing signal detector comprises: a reflecting section mounted on the movable section; a light emitting section separate from a laser beam used for reproducing information fixed to the optical head; and a light emitting section from the light emitting section. The optical information reproducing apparatus according to claim 1, further comprising: a light receiving portion for receiving the emitted light after the light is reflected by the reflecting portion. 10. An optical head for reproducing information has a plurality of objective lenses having different aperture ratios, and an optical system for reproducing information, and a movable part on which the objective lens is mounted is moved to move the plurality of the plurality of objective lenses. In an optical information reproducing apparatus for reproducing optical disks having different physical characteristics by switching the lens of the optical system to the optical system, an identification signal detecting means for identifying the objective lens mounted on the movable part is provided. Optical information reproducing device. 11. The identification signal detector means is composed of a light reflecting portion provided on a surface on a side where the optical system is formed on both side sides in the track direction of the objective lens, and the reflecting portion. The presence or absence of or a combination of reflecting portions having different reflectances are arranged differently for each objective lens, and the detection of the identification signal is performed by using a laser beam and a photodetector for reproducing information, and 11. The optical information reproducing apparatus according to claim 10, wherein the optical information reproducing apparatus is configured to detect reflected light from the optical information reproducing apparatus. 12. The identification signal detecting means is constituted by a through hole provided between the objective lenses, and the detection of the identification signal causes the movable part to swing to the left and right and from the optical system. The information reproducing light beam emitted is reflected by the reflection surface attached to the optical disc or the disc mounting mechanism above the optical head through the through hole, and the reflected light of the optical beam is detected. The optical information reproducing device according to claim 10, characterized in that. 13. The identification signal detecting means includes a reflecting section mounted on the movable section, a light emitting section other than a laser beam used for reproducing information fixed to the optical head, and a light emitting section from the light emitting section. 11. The optical information reproducing device according to claim 10, wherein the optical information reproducing device comprises a light receiving portion for receiving the emitted light after it is reflected by the reflecting portion. 14. The identification signal detecting means includes a reflecting portion or a through hole provided between a plurality of objectives of the movable portion, a swing signal generator for swinging the movable portion left and right, and a signal detector. It is composed of a reflected light amount detector obtained from the above, and a comparison circuit for comparing the swing signal and the reflected light amount detection signal. 11. The optical information reproducing device according to claim 10, wherein 15. An objective lens is determined based on an output of an identification signal detector capable of identifying the objective lens mounted on the movable part, and then a focus search is performed using the determined objective lens to detect a disc. The optical information reproducing device according to claim 10, wherein the optical information reproducing device is specified. 16. It is confirmed whether or not the lens switching is normally operated based on the output of an identification signal detector capable of identifying the objective lens mounted on the movable part,
11. When the switching operation failure occurs, the pulse width of the kick pulse for switching the lens is increased or decreased to perform the switching operation again. Information reproduction device. 17. An optical head for reproducing information has an optical system for reproducing information and a plurality of objective lenses having different aperture ratios, and moves a movable part on which the objective lenses are mounted to move the plurality of the objective lenses. In an optical information reproducing apparatus for reproducing optical disks having different physical characteristics by switching the lens of the optical system to the optical system, the optical disk is reproduced by using laser light for information reproduction passing through a through hole provided in the movable part. An optical information reproducing apparatus characterized in that the type of the optical disk is judged by receiving the light reflected from the optical detector for reproducing information.