JP2001093175A - Optical system driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical system driving device which is designed for an optical system for converging light on each layer of a multi-layer film and which is capable of controllably holding the optical system at plural positions within a driving area. SOLUTION: A magnetic piece 8 is attached to a movable part, in which an optical system 1 for converging light on each layer of a multi-layer film and driving coils 3a, 3b for driving at least in one direction are integrally fixed, and at least three magnetic detecting elements H are arranged in the driving direction oppositely to the magnetic piece, on a fixed part in which magnetic circuits 7a, 7b are assembled for driving the movable part in a prescribed direction in cooperation with the driving coils. As a result, the optical system can be controllably held at plural positions within the driving area. The device is effectively applied to an optical information recording and reproducing device that, by a multiplex recording/reproducing method advantageous for high recording density, records and/or reproduces information on a recording medium such as a disk having a number of recording layers at intervals of a minute distance in the depth direction of the recording medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical system driving device, and more particularly, to an optical information recording device for projecting a light spot on a recording medium such as a disk through an objective lens to optically record and reproduce information. The present invention relates to an optical system driving device of a reproducing apparatus.

[0002]

2. Description of the Related Art In an actuator for supporting or driving an optical system, a sensor for detecting the position of the optical system is used to hold the optical system at a predetermined position. For example, those disclosed in JP-A-62-141638 (Reference 1) and JP-A-63-108538 (Reference 2) are mentioned as examples thereof. 2. Description of the Related Art An optical system supporting device that combines a Hall element and serves as a position sensor has been conventionally proposed.

[0003]

(A) In the specific configuration disclosed in this type of apparatus, there is only one position that can be detected by the position sensor. Therefore, when there is only one detectable position, the optical system cannot be controlled and held at a plurality of positions.

(B) If controlling and holding the optical system at two or more positions can be realized accurately, reliably, and accurately, this can be achieved by, for example, a recording layer of a disk-shaped recording medium. This is particularly useful when an optical system that condenses light on each layer of the multilayer film set at different positions in the depth direction at minute intervals is particularly useful.

(C) Japanese Unexamined Patent Application Publication No. 7-21565 (Document 3) discloses recording on an optical disc having a plurality of recording layers in a depth direction so as to achieve high recording density recording and reproduction.
An optical information recording / reproducing apparatus using a multiplex recording / reproducing method capable of reproducing is shown. There, a recording / reproducing beam from a recording / reproducing light source is focused on a plurality of different positions in the depth direction of the optical disc. Here, when condensing light on each of the recording layers, for example, by using a collimator lens displacement actuator (1012) shown in FIG. Light source corresponding to each,
Compared to the case of FIG. 2 of the same publication using an optical system, this is advantageous because it is not necessary to separately provide corresponding optical components for each layer.

(D) Therefore, as discussed in (b) and (c) above, such an optical information recording / reproducing apparatus is particularly advantageous. On the other hand, Japanese Patent Application Laid-Open No. Hei 7-21565. In the official gazette (Document 3), there is no specific description about the configuration of such an actuator (1012).

(E) An optical system for condensing light on each layer of a recording / reproducing multilayer film of a recording medium is intended to be realized by controlling and holding the optical system at a plurality of positions. In this case, if this cannot be performed properly, as described in (c) above, the above-mentioned multiplex recording / reproducing method which brings an effect effective for high density should be fully exhibited. Is also difficult.

The present invention is based on the above considerations and further on the basis of considerations described later, and is intended to realize the following means for controlling and holding an optical system at a plurality of positions. It embodies this with the idea of being extremely effective.

[0009]

According to the present invention, the following optical system driving device is provided. That is, the optical system driving device according to the present invention is configured such that a magnet piece is attached to a movable part in which an optical system for condensing light on each layer of the multilayer film and a driving coil for driving at least one direction are integrally fixed, Characterized in that at least three magnetic detecting elements are arranged in the driving direction, facing the magnet piece, on a fixed part incorporating a magnetic circuit for driving the movable part in a predetermined direction in cooperation with the magnetic piece. It is.

Thus, the optical system can be controlled and held at a plurality of positions within the driving range. In the conventional device that does not employ the present invention in which there is only one position that can be detected by the position sensor, there is no problem as described in the above (a), and light is focused on each layer of the multilayer film. The optical system enables the above to be appropriately realized.

Therefore, as described in (b) to (e) above, the present invention is particularly suitable and advantageous when an optical system for condensing light on each of a plurality of recording layers of a recording medium is used. The optical system driving device of the present invention is applied to an optical information recording / reproducing apparatus according to the above-described multiplex recording / reproducing method which has an effect and is effective for increasing the recording density, thereby making the method more effective. Make things possible.

The optical system driving apparatus according to the present invention having the above-described structure capable of controlling and holding the optical system at a plurality of positions is also expanded as a structure capable of increasing the detection sensitivity and improving the accuracy of the position control. Can be implemented. As in the preferred embodiment described later, the resolution can be improved by setting a large number of position-controllable positions, and therefore, a disk-shaped or the like having a large number of recording layers at a very small distance in the depth direction of the information recording medium. It is more effective when applied to the above-mentioned optical information recording / reproducing apparatus for recording and / or reproducing information on / from the recording medium.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 show one embodiment of the present invention. FIG. 1 shows an optical information recording / reproducing apparatus including an optical system driving apparatus according to an embodiment of the present invention. The recording / reproducing apparatus applied here is an optical recording / reproducing apparatus that optically records and reproduces information by projecting a light spot on a recording medium such as a disk via an objective lens. More specifically, an optical information recording / reproducing apparatus which performs recording and reproduction on an information recording medium having a plurality of recording layers and one reflection surface in a depth direction. 2 and 3 are a perspective view and a sectional view showing an example of the configuration of the optical system driving device. FIG. 4 is an enlarged explanatory view for explaining the relationship between the magnets in FIGS. 2 and 3 and the Hall element opposed thereto, and FIG. 5 is an example of a circuit portion of a detection system to which the present invention can be applied.

In FIG. 1, the optical information recording / reproducing apparatus has two optical systems each including a light source. One of them is to move an objective lens 55 to a layer (reflection surface 58) serving as a guide (a guide for focus or tracking servo) in the information recording medium 56 to form a light spot. The other is for projecting a light spot on the information recording medium 56 via the objective lens 55, and the recording layers 57 in the information recording medium 56 have respective layers 57a, 57b, and 57c.
For example, the collimator lens 1 can be moved to connect a light spot of a recording / reproducing beam for optically recording and reproducing information.

In the optical information recording / reproducing apparatus shown in FIG. 1, a laser diode 51 is provided as a servo light source. The servo beam from the laser diode 51 converts the beam into a collimator lens 52, a half mirror 53,
The information recording medium 56 is radiated through the half mirror 54 and the objective lens 55, is condensed on the reflection surface 58 through the plurality of recording layers 57, and the reflected light is transmitted to the objective lens 55, the half mirror 54, and the half mirror 53. , And is received by the error detection system 59, and the servo circuit 60
, And drives the objective lens actuator 61 to perform focus or tracking servo.

A laser diode 62 is provided as a recording / reproducing light source. The beam from the laser diode 62 passes through a collimator lens 1, a half mirror 64,
The light is focused on a desired layer (recording layer) of the plurality of recording layers 57 of the recording medium 56 via the half mirror 54 and the objective lens 55. At the time of reproduction, in order to read out the multi-layer recorded data, the reflected light from the corresponding recording layer is further transmitted to the objective lens 5.
5, half mirror 54, half mirror 64, lens 65
Then, the light is received by the photodetector 67 through the pinhole 66, and the information recorded on the desired recording layer is reproduced based on the output.

Therefore, the system of the laser diode 62 and the collimator lens 1 is used as an optical system for condensing the beam from the laser diode 62 on each layer of the recording layer 57 of the recording medium 56. Here, in this embodiment,
The collimator lens 1 is driven and controlled by the optical system driving device 100 according to the present invention so that the optical system can be controlled and held at a plurality of positions.

In the present optical system driving device 100 (a driving and supporting device for a collimator lens), a magnet 8 is mounted on a movable portion M in which the collimator lens 1 and a driving coil 3 for driving in at least one direction are integrally fixed. In addition, at least three Hall elements H are mounted on a fixed part in which a magnetic circuit 7 for driving the movable part M in a predetermined direction (here, the optical axis direction of the collimator lens 1) in cooperation with the drive coil 3 is incorporated. , And is arranged in the driving direction D so as to face the magnet 8. In this case, the laser diode 62 as a light source can be arranged on the side of the fixed part.

The current supply to the drive coil 3 of the optical system drive device 100 is controlled under the control of the drive circuit 68. Here, the drive circuit 68 can be configured as a control unit including a microcomputer, for example.

In this case, the drive circuit is provided with a layer selection signal (a first position, which will be described later, where the collimator lens 1 is to be positioned when controlling to a plurality of positions within the drive range of the collimator lens 1). , An input detection circuit for inputting a position to be taken, such as a "second position", and other input information (for example, an output terminal signal in FIG. 5), and an arithmetic processing circuit (CPU). , A storage circuit, and an output circuit that supplies current to the coil 3 that drives the movable portion M of the optical system driving device 100.

Thus, the collimator lens 1 is formed by the magnet 8 of the movable portion M and the three or more Hall elements H of the fixed portion, as described above, according to the layer selection signal instructed by the drive circuit 68. Is driven in the optical axis direction by an optical system driving device 100 that can control and hold the position at a plurality of positions within the driving range. Thereby, the recording / reproducing beam can be focused on the recording layer 57 corresponding to the layer selection signal.

The specific configuration, functions, and the like of the optical system driving device 100 can be more preferably implemented as those described below, and will be described in further detail with reference to FIG. I do. What is shown in FIGS.
This is a configuration example of a mechanism and peripheral parts mainly related to the drive coil 3, the magnetic circuit 7, the magnet 8, the Hall element H, and the like in the optical system driving device 100.

FIG. 5 shows a configuration example of a circuit portion of a detection system to which the present invention can be applied. Here, each adding circuit A in FIG.
12, A23 and A34 can be configured to be incorporated as a part of the drive circuit 68. In that case, the signal information appearing at the output terminals T12, T23, T34 can be used as input information when the drive circuit 68 controls the energization of the coil 3. In addition, in the examples in FIGS. 2 to 5, the positioning position of the collimator lens 1 is an example of three places, and the collimator lens 1 is formed by the magnet 8 of the movable part M and the four Hall elements H of the fixed part. Is controlled at three positions within the driving range and can be held. Therefore, the multiple recording layer of the recording medium 56 to which the present invention is applied is an example in which the recording layer 56 has three recording layers 57.

Referring to FIGS. 2 and 3, as shown in FIGS.
Here, the collimator lens 1 is adhered and fixed to the cylindrical portion of the holder 2, and as shown in FIG. 1, converts the divergent light beam emitted from the laser diode 62 into substantially parallel light.

Air-core drive coils 3a and 3b are adhered to both side surfaces of the holder 2. Further, two support springs 4a and 4b are attached to the rear end of the holder 2. One end of each of the two support springs 4 a and 4 b is fixed to the holder 2, and the other end is fixed to the holding member 5. In this example, the movable portion can be configured to include the holder 2 in which the collimator lens 1 and the drive coils 3a and 3b are integrally fixed.

The holding member 5 is arranged near the rear end of the base 6, and the base 6 and the holding member 5 are positioned and fixed by bosses and holes (not shown).
Drive coils 3a, 3b provided on both sides of the holder 2
Magnetic circuits 7a and 7b for driving the above movable parts in cooperation with
Are provided on the base 6. In this example, the fixing part can be configured to include the base 6.

The magnetic circuits 7a and 7b attached to the base 6 as the fixed parts are respectively magnetic circuits 7a and 7b.
The base 6 is incorporated on both sides near the front end of the base 6 so that the magnetic flux passing through the drive coils 3a and 3b crosses the drive coils 3a and 3b. Therefore, the magnetic flux of the magnetic circuits 7a and 7b attached to the base 6 traverses the drive coils 3a and 3b.
By applying a current to the drive coils 3a and 3b under the control of the drive circuit 68, an electromagnetic force corresponding to the current flows in the optical axis direction (FIG. 3).
(A dashed line), the support springs 4a and 4b are bent and deformed, and the collimator lens 1 is displaced in the optical axis direction. Thus, the configuration is such that the collimator lens 1 is driven in the optical axis direction. Therefore, due to the displacement of the collimator lens 1, the light beam from the laser diode 62 slightly deviates from the parallel light as shown in FIGS. 1 and 3 and becomes a slightly convergent light or a slightly divergent light.
5, the position of the light spot converged can be slightly moved in the optical axis direction.

On the other hand, a magnet 8 is mounted on the holder 2, and a Hall element H is disposed opposite to the magnet. Here, as shown in FIG. 3, the holder 2 has a projection 2a at the front end thereof, and the magnet 8 is bonded and fixed to the tip of the projection 2a. The magnet 8 bonded and fixed to the tip of the projection 2a of the holder 2 has a magnetic pole parallel to the driving direction D as shown in an enlarged view in FIG. 4 (therefore, in FIG. In the drawing, four Hall elements H1 to H4 are arranged on the plate 9 standing upright from the base 6 with a slight gap facing the magnet 8 in the driving direction. Adjacent to the drive direction, a magnetic signal line 10 is arranged so that an electric signal is output when the magnetic force lines 10 penetrate in a direction perpendicular to the drive direction (left-right direction in FIG. 4).

The arrangement intervals of the Hall elements H1 to H4 are set according to the intervals between the respective recording layers 57 of the recording medium 56 where recording / reproduction is to be performed. In this case, the arrangement of the Hall element H can be selected in consideration of the magnification of the collimator lens 1 and the objective lens 55 to be used.

Here, in the present example, for example, when the minute interval between the recording layers 57 on the recording medium 56 side is “x”, one pitch (corresponding to one element) length h on the Hall element H side. Is the size of the minute interval “x” expanded m times.
= X × m. In this case, when the magnet 8 at the tip of the collimator lens holder (and thus the collimator lens 1) is driven by the pitch length h in the driving direction D with respect to the row of the Hall elements H1 to H4,
On the recording medium 56 side, the position of the light spot may be set so as to be moved in the optical axis direction (that is, in the depth direction of the medium 56) by a small amount appropriately in accordance with each recording layer 57 by “x”. It is possible.

Further, in this example, the Hall elements H1 to H4 are, as shown in FIG. 5, a circuit section having first, second and third adders A12, A23 and A34. Then, it is configured to be connected and connected as shown in FIG. The output signals (output voltages) of the adjacently arranged Hall elements H1 and H2 in the Hall element array provided in the above-described arrangement are provided as inputs to the first adder circuit A12. A signal obtained as a sum signal is output from an output terminal T1 of the addition circuit.
2 is output. Here, when the polarities of both signals are opposite and the magnitudes are equal, the output of the terminal T12 is zero.

Hall elements H2 which are arranged adjacent to each other
The same applies to the case of the Hall element H3 and the case of the Hall element H3 and the hall element H4. The output signal of each of the Hall element H2 and the Hall element H3 is the second output signal.
, And a signal obtained by calculating the sum of the signals is output to an output terminal T23 of the addition circuit A23. Hall element H3 and Hall element H4
Are provided as inputs to a third addition circuit A34, and a signal obtained by calculating the sum of the signals is output to an output terminal T34 of the addition circuit.

The signal information appearing at the output terminals T12, T23, and T34 can be effectively used for position detection at each of the three positions to be position-controlled. When the drive circuit 68 controls the collimator lens 1 to control the position of the collimator lens 1 to the designated corresponding position, the information can be used as information on current control of the drive coils 3a and 3b.

For example, when the position command information (layer selection signal) is given, the drive circuit 68
Is determined to be the commanded position, and if the commanded position matches the current control, the current control state of the drive coils 3a and 3b is maintained. For example, while the variable control of the current is performed, the addition circuits A12, A
23, the signals at the output terminals T12, T23, T34 of A34 are monitored, and when the output of the adder circuit corresponding to the commanded position indicates zero, it is determined that the commanded position has been detected, and the drive coils 3a, 3b The current is maintained in that state, and can be used as information for current control of the drive coils 3a and 3b when the drive circuit 68 controls in this way.

Hereinafter, the operation of the present apparatus will be described more specifically. Lines of magnetic force 10 emerging from magnet 8 (FIG. 4)
Crosses the neighboring Hall elements (H1 to H4), and an electric signal is output from the Hall elements.

Here, in this configuration, the magnetic poles of the magnet 8 are parallel to the driving direction D, and the rows of Hall elements H1 to H4 are in the driving direction D.
Is arranged so that an electric signal is output when the magnetic force line 10 penetrates in a direction perpendicular to the direction of the magnetic field lines 10, and as a result, the magnet is located near the adjacent Hall element where the sign of the Hall element output voltage is inverted. Can be detected. Further, the sum signal of the output voltage is calculated by the detection system having the circuit configuration of FIG. 5, and the position of the collimator lens 1 can be controlled to a position where the sum signal becomes zero. That is, for the sum signal of H1 and H2, the sum signal of H2 and H3, and the sum signal of H3 and H4, three positions (“first position”, “second position”, and “third position”)
Thus, the position of the collimator lens 1 can be controlled and held. Here, the “second position” indicates that the divergent light from the laser diode 62 is
The "first position" is a position where the light beam is slightly deviated from the parallel light and slightly converges, and the "third position" is a position where the light beam is a parallel light. This is a position where the light slightly deviates from the position and becomes a slight divergent light.

For example, in the state shown in FIGS. 3 and 4, the output voltage of the Hall element H2 and the output voltage of the Hall element H3 are opposite to each other in the direction of the magnetic force lines 10 passing through the Hall element, and the polarity of the generated voltage is opposite. Are opposite to each other. In this case, as shown in FIG. 5, the adders A12, A23, A
34, the output voltage of the Hall element H2 and the output voltage of the Hall element H3 having such a relationship are added by the second adder circuit A23 among them. Only the output terminal T23 can make its output signal (sum signal) zero. Therefore, when the signal of the output terminal T23 of the second addition circuit A23 is zero, this means that the position of the magnet 8 is exactly the same as that of the magnet 8 attached to the tip of the projection 2a of the holder 2 in FIG.
Illustrated position (between adjacent Hall elements H2 and H3,
Or its vicinity) (position detection).

Accordingly, when the position of the collimator lens 1 is to be set at a position where the tip (magnet 8) of the projection 2a of the holder 2 assumes the position shown in FIGS. The unit can realize this by performing the following control (position control). In this case, the drive circuit 68 supplies the layer selection signal as input information given at this time, that is, the position command information as described above (position command information for commanding the position where the collimator lens 1 should be located. FIG.
Based on "second position" command information for commanding that the illustrated position is to be taken, and also on the basis of addition circuits A12, A
Signals from the output terminals T12, TA23, T34 of the control coils 23, A34 are used as control information, and while monitoring this information, the second control is performed in the energization control to the drive coils 3a, 3b.
The above control can be performed by controlling the current (current value) to be supplied to the drive coils 3a and 3b by adjusting the current (current value) to be adjusted so that the signal generated at the output terminal T23 of the adder circuit A23 becomes zero. Thus, the position of the collimator lens 1 can be controlled to the position, that is, the “second position” at which the divergent light from the laser diode 62 can be converted into parallel light.

The relationship between the detection and the control is such that the magnet 8 is located between the Hall elements H1 and H2 of the Hall elements H1 to H4 arranged in the driving direction D opposite thereto and the Hall element H3. The same can be said for H4. Therefore, the other "first position" and "third position" among the above three positions are also established.

That is, with respect to the control position (“second position”) shown in FIGS. 3 and 4, the position is shifted upward by one step (one pitch length h) so as to be controlled to “first position”. When trying to control the position of the collimator lens 1 so that the magnet 8 is raised so that the magnet 8 is located just between the Hall elements H1 and H2 (a position where the light beam from the collimator lens becomes a slight convergent light), or vice versa In order to control the collimator lens 1 so as to be controlled to the "third position", the position is lowered by one step (one pitch length h) downward in the figure so that the magnet 8 is located near the position between the Hall elements H3 and H4. The control to a position (a position where the light beam from the collimator lens becomes a slight divergent light) can be realized according to the above-described case.

Therefore, the position command information (layer selection signal)
In this case, the recording / reproducing beam can be converged on the recording layer 57 corresponding to the above, and in this case, the sum signal of the outputs of the Hall elements H1 and H2 (output to the output terminal T12 of the addition circuit A12). Signal), the sum signal of the outputs of the Hall element H2 and the Hall element H3 (the signal output to the output terminal T23 of the addition circuit A23), and the sum signal of the outputs of the Hall element H3 and the Hall element H4 (the output of the addition circuit A34). The position of the collimator lens 1 is appropriately controlled at three positions in relation to the signal output to the terminal T34).
It is possible to easily and accurately connect the light spot to the corresponding recording layer 57.

[Modification of First Embodiment, etc.] In this embodiment, the plate 9 shown in FIGS.
May be a magnetic material. In this case, as shown in FIG. 4, the magnetic force lines 10 can pass through the plate 9 of the magnetic material. As a result, the lines of magnetic force crossing the Hall element (in the example of FIG. 4, the Hall element H near the N pole of the magnet 8).
2 is a magnetic field line passing from the right side to the left side of the plate 9 in the figure, and is a Hall element H3 near the S pole of the magnet 8.
The number of magnetic lines passing rightward from the left side of the plate 9 in the figure increases, the output of the Hall element increases, the detection sensitivity increases, and the accuracy of position control improves. The present invention can also be implemented in this way.

In the case of this embodiment, the detection sensitivity can be increased and the accuracy of the position control can be improved by such a method. The configuration of the above embodiment, in which a light spot can be accurately and reliably formed on the corresponding recording layer in accordance with each layer of the recording layer 57, is a collimator lens 1 for condensing light on each layer of the recording layer of the recording medium 56. In addition to the above, when the present invention is applied, a suitable and advantageous effect is obtained, but in addition to the above, it is more effective to implement the configuration in which the detection sensitivity is increased and the position control accuracy is improved as described above. Since the detection sensitivity can be improved and the accuracy of the position control can be improved, it is possible to more accurately and surely condense light to each layer of the multilayer film. Therefore, the above-mentioned specification which is advantageous for high density recording and / or reproduction of information on a recording medium such as a disk having many recording layers at a minute distance in the depth direction of the information recording medium. The advantages of the multiple recording / reproducing method described at the beginning of the book
It is possible to make it more fully exhibited.

Next, another embodiment of the present invention will be described. FIG. 6 shows a main part of another embodiment (second embodiment) of the present invention, and is a partially enlarged view corresponding to FIG. 4 in the first embodiment. Basically, the configuration is the same as that of the first embodiment. Therefore, the description of the same configuration as that of the first embodiment will be omitted, and the main part of this embodiment which is different from the first embodiment will be described below. .

In this embodiment, as shown in FIG.
Magnet 1 adhesively fixed to the tip of projection 2a of holder 2
1 is different from the case of FIG.
(In FIG. 6, the N and S poles are arranged in the left-right direction.) Further, the n Hall elements H1 to H1 with a slight gap facing the magnet 11 are provided.
Hn is arranged adjacent to the plate 9 standing upright from the base 6 in the driving direction, so that an electric signal is output when the magnetic force lines 12 penetrate in a direction parallel to the driving direction.

Here, regarding the configuration of the hall element row,
As can be seen from a comparison between FIGS. 4 and 6, in FIG. 6, a stacked arrangement of thin Hall elements can be used. In the case of such a stacked arrangement of thin Hall elements, in the first embodiment, the above-described one pitch length h corresponding to one element on the side of the Hall element H is the position when the collimator lens 1 is positioned. This is also the interval between the first to third positions that can be detected, and the multiple recording layers 57 on the side of the recording medium 56 to which it is applied.
However, in the present embodiment, it can be understood that this relationship can be made finer.

In the optical system driving apparatus 100 of the present embodiment, the magnetic field lines 12
Crosses the neighboring Hall element H, and the Hall element outputs an electric signal. Here, the position of the magnet (11) can be detected from the sign (polarity) of the Hall element output, and the position of the collimator lens 1 can be controlled to a position where the sum signal of the adjacent Hall element outputs becomes zero. , And the same as the first embodiment.

According to this embodiment, the same operation and effect as those described in the first embodiment can be obtained. Therefore, the conventional sensor not adopting the present invention in which the position sensor can detect only one position is provided. In addition to the inconveniences as described at the beginning of the specification (a) in the apparatus, it is of course possible to control and hold the optical system for condensing light on each layer of the multilayer film at a plurality of positions within the drive range. it can.

Therefore, the beginning (b) of the description
As described in (e), an optical system driving device which is particularly suitable and has advantageous effects is applicable to a case where an optical system for condensing light on each of a plurality of recording layers of a recording medium is targeted. Can be provided. Therefore, when the optical system driving device according to the present invention is applied to the optical information recording / reproducing apparatus according to the above-described multiplex recording / reproducing method which is advantageous for increasing the recording density, the advantage of the method is also reduced. It can be used more than enough and can be used up enough.

Further, according to the present embodiment, in addition to the above, since the thin Hall elements are stacked and arranged, a large number of controllable positions can be set within the driving range of the collimator lens 1. Therefore, the resolution can be increased, and the resolution can be made finer.
Further, by adding and calculating the outputs of a plurality of adjacent Hall elements, the detection sensitivity is increased and the accuracy of the position control is improved.

The present invention is not limited to the above embodiment. For example, in the first and second embodiments, the Hall element H is used as the magnetic detecting element. However, any other magnetic detecting means such as a magnetoresistive element may be used as long as the magnetic force can be detected. Is also good. Also, for example, the types of magnets used as the magnet pieces are rare earth magnets,
Any material having magnetism such as a ferrite magnet or a bond magnet may be used.

The optical information recording and / or reproducing apparatus and the recording medium to which the present invention can be applied are shown in FIG.
Are not limited to those shown in FIG.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an optical information recording / reproducing device including an optical system driving device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing an example of the configuration of the optical system driving device of the same example.

FIG. 3 is a cross-sectional view for explaining an optical system driving device of the same example.

FIG. 4 is also a partially enlarged view of FIG.

FIG. 5 is a diagram showing an example of a circuit portion of a detection system to which the present invention can be applied.

FIG. 6 is a partially enlarged view of a main part of another embodiment of the optical system driving device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Collimator lens 2 Holder 2a Projection 3 Drive coil 3a, 3b Drive coil 4a, 4b Support spring 5 Holding member 6 Base 7 Magnetic circuit 7a, 7b Magnetic circuit 8 Magnet 9 Plate 11 Magnet 54 Half mirror 55 Objective lens 56 Information recording medium 57 Recording layer 58 Reflecting surface 62 Laser diode 64 Half mirror 65 Lens 66 Pinhole 67 Photodetector 100 Optical system driving device A12, A23, A34 Addition circuit H, H1, H2, H3, H4, Hn Hall element M Moving section T12, T23, T34 output terminal

Claims (1)

[Claims] 1. A magnet piece is attached to a movable part in which an optical system for condensing light on each layer of a multilayer film and a drive coil for driving at least one direction are integrally fixed, and the movable piece is cooperated with the drive coil. An optical system driving device, wherein at least three magnetism detecting elements are arranged in a driving direction opposite to the magnet pieces in a fixed portion incorporating a magnetic circuit for driving the portion in a predetermined direction.