JP2874641B2 - Objective lens drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording / reproducing apparatus for recording optical information on two different types of optical discs and reproducing the information from each of the two types of optical discs. More particularly, the present invention relates to a drive device that selectively uses two types of objective lenses that can be stably operated by a mechanically balanced configuration.

[0002]

2. Description of the Related Art Conventionally, when recording and reproducing optical information on an optical disk, in order to use one pickup for both a conventional CD and a new DVD system, it is necessary to support both systems. Two types of objective lenses with different specifications such as focal length and numerical aperture are mounted and used properly.
In this case, it is important to make the structure of the lens holder small and to smoothly and quickly switch between the two types of objective lenses. For this purpose, various driving devices that use two types of objective lenses properly have been proposed.

FIG. 6 is a diagram for explaining an example of a conventional example using magnetic force balance. The mechanism section shown in FIG. 6 includes two types of objective lenses 101 and 102 each having a cylindrical lens holder 1.
03, which is supported on the outer frame by the rotating shaft 104 and rotated, and used properly in accordance with each system. The lens holder 104 has two pairs of track coils 105.
a, 105b, 106a, 106b and two pairs of magnetic pieces 10
7a, 107b, 108a, and 108b are laminated and attached to each other. Each pair is arranged on the side surface of a rotating cylinder with point symmetry with respect to the rotation axis, and a focus coil (not shown) is similarly provided on the bottom surface.

A track magnet 109a, 109b facing each of the track coils 105a, 105b, 106a, 106b is provided on an outer frame for supporting the yoke 110.
, And a focus magnet 111 facing the focus coil is provided below the lens holder 104. Each track magnet 109a, 109
b is excited by two poles in the rotation direction of the lens holder 104. In this mechanism, since the track coil and the focus coil are provided independently of each other, a track magnet and a magnetic piece, and respective magnetic circuits including the focus magnet and the focus coil are also required independently.

FIG. 7 is a diagram for explaining the operation of the conventional example in FIG. The magnetic holding force C shown in FIG. 7 changes along the forward and reverse rotation directions,
At two steep neutral points A and B formed by the magnetic fluxes 09a and 109b, each magnetic piece 107a, 107b,
The lens holder 10 is strongly attracted to the lens holder 10.
4 can be stably held in the rotation direction.

On the other hand, each track coil 105a, 105
b, 106a, 106b, the magnetic fluxes of the respective magnetic pieces 107a, 107b, 108a, 1
The lens holder 104 can be rotated by canceling the magnetic flux 08b and applying a kick pulse current that repels the magnetic fluxes of the track magnets 109a and 109b. That is,
By sequentially performing the rotation and the holding in the rotation direction, two types of objective lenses can be selectively used.

[0007]

However, the following problems arise when a conventional dual-purpose objective lens is used and a dual-purpose pickup corresponding to two types of optical disks is designed to be small and light. There was a point. First
In particular, the mechanical section has to be complicated and particularly large in the height direction, and it is necessary to balance the weight of the large lens holder.

Second, since the magnetic piece uses an inexpensive mass-produced type, the magnetic flux density, that is, the variation in the magnetic holding force cannot be ignored, and in order to rotate and hold the lens holder stably, It was necessary to precisely control the size and the distance from the track magnet, which increased the manufacturing cost.

Third, since variations in the magnetic coercive force tend to cause secondary higher-order resonance in the mechanism section, it is essential to eliminate it, which has been a difficult design.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and can stably operate in a recording / reproducing apparatus for an optical disk using two types of objective lenses due to a mechanically balanced structure. It is an object of the present invention to provide an objective lens driving device that selectively uses two types of objective lenses.

[0011]

According to the present invention, there is provided a driving apparatus for selectively using two types of objective lenses, comprising two types of objective lenses for receiving optical information of an optical disk, and at least two sets of coils. An objective lens driving device that comprises a substantially cylindrical lens holder that slides in the direction of the rotation axis while rotating itself, and selectively uses these two types of objective lenses according to the type of optical disc. The lens holder is provided with two reflectors arranged at right angles to the rotation axis, and at least one rotation position sensor facing the two reflectors by the rotation of the lens holder is provided on the outer frame, and lens
Outputs a position signal and controls based on this lens position signal.
Switch the coil that gives the control signal, and
Tracks by synthesizing the position error signal and the track error signal
For generating the control signal . According to this drive device, two reflectors arranged at right angles to the rotation axis are provided on the cylindrical side surface of the lens holder, and a rotation position sensor facing the two reflectors by the rotation of the lens holder is provided on the outer frame. .

[0012]

Embodiments of the present invention will be described below with reference to the drawings. In addition, each part denoted by the same reference numeral as the conventional example is a part having the same function, and detailed description is omitted. FIG. 1 illustrates an embodiment according to the present invention, which will be described later.
In explaining, the objective lens drive to be controlled
FIG. 3 is a diagram illustrating a configuration of an embodiment of a mechanism unit of the apparatus;
FIG. 1A is a plan view, and FIG. 1B is a cross-sectional view as viewed from the direction of arrow ii-ii in FIG. Shown in FIG.
The mechanism of the embodiment includes a new lens holder 3 in which a pair of first coils 1a and 1b and a second coil 2a and 2b are provided on a cylindrical side surface, and a track magnet 4a for holding the cylindrical side surface in a rotational direction. 4b and a new outer frame 6 provided with a pair of focus magnets 5a and 5b for holding the magnets in the direction of the rotation axis.

The lens holder 3 has two different objective lenses 31 and 32 arranged at an angle of, for example, 90 ° with respect to the rotation axis, and a laser beam 34 transmitted through the optical disk 33 transmits the objective lenses 31 and 32 and the reflector 35 to each other. It can be introduced into a reading unit (not shown) via the interface. Further, the rotation shaft 36 of the lens holder 3 is supported by the outer frame 6. The first and second coils 1a, 1b, 2a, 2b form a quadrilateral having two sides parallel to the rotation direction and two sides parallel to the rotation axis,
They are arranged symmetrically with respect to a rotation axis by 90 °.

The track magnets 4a and 4b move in the direction of rotation of the lens holder 3 and the focus magnet 5
a and 5b also have a dipole field in the direction of the rotation axis, respectively. When the lens holder 3 makes a quarter turn, the position and height on the side of the cylinder become the coils 1a, 1b, 2a and 2b.
It is arranged to face. In addition, each magnet 4
A yoke 7 for forming magnetic circuits a, 4b, 5a and 5b is provided on the outer frame 6.

[0015] Figure 2 is a diagram for explaining the magnetic action of the track magnet in FIG. 1 (b), a cross-section in FIG. 2 (a) mechanism, the arrows in FIG. 2 (b) FIGS. 2 (a) FIGS. 2C and 2C show cross sections as viewed from the direction of iii-iii, respectively, and FIG. 2C is a view as viewed from the direction of arrow iv-iv in FIG. 2B. The track magnets 4a and 4b shown in FIG. 2A are, for example, opposed to the first coils 1a and 1b, so that one of the objective lenses 31
3 is used.

[0016] Here, the track magnet 4a (4b) shown in FIG. 2 (b) is divided from the center in the vertical direction on the drawing to the right and left two regions, each region has a different magnetic poles. For example, the left region 4aL in the drawing has the first coil 1a side as the N pole and the right region 4aL as the north pole.
aR magnetizes the S pole similarly.

At this time, when the current I1 of the first coil 1a is clockwise in the drawing, the magnetic repulsion P1 shown in FIG. 2C acts on the first coil 1a, and this repulsion P
The lens holder 3 is rotated in the direction of 1. The two first coils 1a and 1b are connected in series, and rotate the lens holder 3 in the same direction jointly.

[0018] FIG. 3 is a diagram for explaining the magnetic action of the focus magnet in FIG. 1 (b), a cross-section in FIG. 3 (a) mechanism, the arrows in FIG. 3 (b) FIGS. 3 (a) It shows each cross section viewed from the direction of vv. Focus magnets 5a, 5 shown in FIG.
b, the second coils 2a and 2b are opposed to each other, so that one objective lens 31 is also used for the optical disc 33.

The focus magnet 5 shown in FIG .
a (5b) is a vertical 2 from the center in the drawing.
And each region has a different magnetic pole. For example, the upper region 5 in the drawing
In aU, the second coil 2a is magnetized to the N pole, and the lower region 5aL is magnetized to the S pole.

At this time, when the current I2 of the second coil 2a is clockwise in the drawing, the magnetic repulsion P2 shown in FIG. 3A acts on the second coil 2a, and the repulsion P
The lens holder 3 floats in the direction 2. Further, by adjusting the current I1, the lens holder 3 can be stably stopped at a position where the lens holder 3 is balanced with the weight.
Note that the two second coils 2a and 2b are also connected in series,
The lens holder 3 is co-rotated in the same direction.

Next, an embodiment according to the present invention will be described with reference to FIG. 1 again. Two optical reflecting plates 8a and 8b are provided on the cylindrical side surface of the lens holder 3, and each is disposed at an angle of 90 ° with respect to the rotation axis. For example, each of the objective lenses 31 and 32 may be provided point-symmetrically . Also,
By the rotation of the lens holder 3, the two reflecting plates 8a, 8b
An optical rotation position sensor 9 is provided on the outer frame 6 so as to face the outer frame. This rotational position sensor 9 is of a differential type having a light emitting unit 9a at the center and two light receiving units 9b and 9c on both sides.
The stop position of each reflector 8a, 8b can be accurately detected in the rotation direction.

FIG . 4 shows a control unit in the embodiment of FIG.
FIG. The first coils 1a and 1b shown in FIG.
Driven by one driver 41a, the second coil 2
a and 2b are driven by the other driver 41b.
You. The above electrical connection and the rotational position sensor 9 etc.
Wiring is controlled from the mechanism by a flexible board
Led to the department.

Here, the objective lens 31 is placed on the optical disk 33.
When the lens holder 3 is rotated, one of the reflectors 8a stops at the point symmetric position of the objective lens 31. The reflector 8a generates an electric signal at the two light receiving sections 9b and 9c of the rotational position sensor 9, finds the difference between the signals, and introduces the difference into the control section as a lens position signal 9d. Subsequently, the lens position signal 9d is introduced to the driver 41a via the terminal A of the switch circuit 44a.

On the other hand, the optical signal detector 43
A signal indicating an optical position of the information track on the third information track is introduced into an error signal generation circuit 44, and the error is generated as a track error signal (TE signal) indicating the position shift via the terminals of a servo switch circuit 44b and a switch circuit 44c. 4
1a. At that time, the servo switch circuit 44b
Are closed by a servo control circuit 45 for controlling fine adjustment of the lens holder 3 (44 in FIG. 4).
b, 44d).

The driver 41a is the lens position signal 9
Based on the composite signal of d and the track error signal (TE signal)
A control signal for the coils 1a and 1b is generated, and the lens position is controlled.
The first coil 1a, 1b acts on the first coil 1a, 1b so that the reflection plate 8a reaches the center of the rotation position sensor 9 to rotate the lens holder 3 to a rotation position where the value of the signal 9d is "0", and a track error signal. The first coil 1 is located at a fine position where no information is generated, that is, so as to optimally scan the information track.
The drive of a and 1b is adjusted. Therefore, the lens holder 3
Is stably held at the rotational position where the objective lens 31 is used, and can correctly follow the optical information on the information track.

[0026] On the other hand, a focus error signal indicating a deviation between the focal point of the objective lens 31 of the information track by the error signal generation circuit 44 (FE signal) is formed, the servo control circuit 4
5, another servo switch circuit 44 also controlled by
d and the driver 41b through the terminal A of the switch circuit 44e.
Will be introduced.

The driver 41b includes the second coils 2a, 2b
To raise the lens holder 3 to the equilibrium height of the weight, and drive the second coils 2a and 2b to a fine position where a focus error signal does not occur, that is, to form an image of the information track correctly. adjust. Therefore, the lens holder 3 can stably hold the focal point of the objective lens 31 on the information track, and can correctly follow the optical information.

One objective lens 31 is connected to another objective lens 3
When switching to 2, the servo control circuit 45
Open the servo switch circuits 44b and 44d of
Control circuit 4 for changing the kick pulse (KP signal) 46
2 and the switch circuit 44c.

FIG . 5 is a diagram specifically explaining each signal when switching to another objective lens in FIG. When the kick pulse 46 shown in FIG. 5 rotates the lens holder 3 toward the use position of another objective lens 32, the reflecting plate 8a moves away from the rotation position sensor 9, and a valley portion in the rotation position signal 9d is generated. A coil switching signal 47a is generated by the switching control circuit 42 after a sufficient time T that can cross the valley portion.

The coil switching signal 47a is introduced into three switch circuits 44a, 44c and 44e, and is switched from the terminal A to the connection of the terminal A.
a, 41b are cut off from each signal, and the driving of the first and second coils 1a, 1b, 2a, 2b is all stopped.
During this time, the lens holder 3 continues to rotate due to its own inertial movement, another reflection plate 8b approaches the rotation position sensor 9 to generate the rotation position signal 9d again, and reaches the center of the neutral point to eliminate the neutral point. A is detected by the switching control circuit 42, and another coil switching signal 47b is transmitted.

[0031] The coil switching signal 47b includes three switch circuits 44a, 44c, is introduced to 44e is switched from the terminal b to the connection terminal c. Therefore, the first coils 1a and 1b can introduce a focus error signal, thereby holding the lens holder 3 in the rotation axis direction. In addition, the second coils 2a and 2b can introduce a track error signal, whereby each control can be switched to hold the lens holder 3 in the rotation direction. After that, the servo control circuit 45 also closes the servo switch circuit 44b and controls the fine adjustment of the lens holder 3 as described above.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that various changes can be made without departing from the spirit of the present invention.

[0033]

As described above, two types of objective lenses according to the present invention are described.
The following effects can be obtained by the drive device that uses the different types of.

[0034] First, since the stop holding the lens holder by the holding force of a conventional magnetic strip, only using the holding force obtained by electrically controlling the magnetic force of the two coils,
There are few factors to consider when setting the holding force of the lens holder, and unnecessary motion due to mechanical structural high-order resonance or the like can be easily suppressed and circuit design can be facilitated.

[0035] Second, in order to detect and control the rotation of the lens holder by an electrical signal of the rotational position sensor, can be switched can be finely monitoring the alignment of the objective lens stably.

As described above, in a recording / reproducing apparatus for an optical disk using two types of objective lenses, it is possible to provide a drive device that selectively uses two types of objective lenses that can operate stably by a mechanically balanced configuration. became.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a mechanism section according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a magnetic action of a track magnet in FIG. 1 (b).

FIG. 3 is a diagram illustrating a magnetic action of a focus magnet in FIG.

FIG. 4 is a diagram illustrating a control unit in the first and second embodiments of FIG.

FIG. 5 is a diagram specifically explaining each signal when switching to another objective lens in FIG. 4;

FIG. 6 is a diagram for explaining an example of a conventional example using magnetic force balance.

FIG. 7 is a diagram for explaining the operation of the conventional example in FIG. 5;

[Explanation of symbols]

 1a, 1b 1st coil 2a, 2b 2nd coil 3 New lens holder 4a, 4b Track magnet 5a, 5b Focus magnet 6 New outer frame 7 Yoke 31, 32 Objective lens 33 Optical disk 34 Laser light 35 Reflector 36 Rotation axis

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G11B 7/085 G11B 7/09 G11B 7/095

Claims (1)

(57) [Claims] 1. An optical disk comprising two types of objective lenses for receiving optical information of an optical disc and at least two sets of coils,
An objective lens driving device that includes a substantially cylindrical lens holder that slides in the direction of a rotation axis while rotating by itself, and uses these two types of objective lenses in accordance with the type of optical disc, and performs recording and reproduction. Two reflectors are provided at right angles to the axis, and the two
At least one rotation position sensor facing the two reflection plates is provided on the outer frame, and a lens position signal is output from the rotation position sensor.
And outputs a control signal based on the lens position signal.
Switching the coil to be applied,
Signal and track error signal for track following
An objective lens driving device, wherein the control signal is generated .