JPH0524570B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical disk player that detects information by focusing a light beam onto a disk using an objective lens.

[Summary of the invention]

The present invention provides an optical disk player that detects information by focusing a light beam onto a disk using an objective lens, in which a movable part consisting of an objective lens, a bobbin, etc. is movable along the optical axis of the objective lens. a support means rotatably supporting the objective lens at a position spaced a predetermined distance from the optical axis; a first coil wound around the bobbin; and a plurality of rectangular coils attached to the bobbin. A second coil made of a rectangular shaped coil, and a magnetic core and a magnet forming a common magnetic circuit that acts on both the first coil and the second coil. One of the windings perpendicular to the coil is arranged in a non-magnetic field part, and a focus servo signal is applied to this first coil to move this movable part along the optical axis of the objective lens to activate the focusing servo. By applying a tracking servo signal to this second coil and rotating this movable part to perform tracking servo, the magnetic circuit is miniaturized, parts are reduced, and efficiency is improved. .

[Problems to be solved by conventional technology and invention]

In an optical disk player, focusing servo (F servo) is performed so that the light beam from the laser light source is accurately focused on the disk through the objective lens, and the information pit row on the disk is aligned with the optical axis of the objective lens. Tracking servo (T servo) is performed so that the

FIG. 1 shows a first conventional device. In this conventional example, a light beam from a laser light source 1 is supplied to a galvanometer mirror 3 through a beam splitter 2.
It is reflected by this galvano mirror 3 and is reflected by the objective lens 4.
is supplied to Note that 5 is an optical disk, and 6 is a motor for rotating the disk 5. Here, the angle of reflection of the galvanometer mirror 3 is changed according to the signal supplied to the coil, and the distance of the objective lens 4 from the disk 5 is changed according to the signal supplied to the coil.

Furthermore, the reflected light from the disk 5 is supplied to a beam splitter 2 through an objective lens 4 and a galvanometer mirror 3, reflected by this beam splitter 2, and supplied to a photodetector 7. and photodetector 7
The reproduced signal detected by is output to the output terminal 8, and the focusing and tracking servo signals detected by a part of the photodetector 7 are supplied to the objective lens 4 and galvano mirror 3, and the F servo and T servo is performed.

That is, F servo is performed by moving the objective lens 4 back and forth, and T servo is performed by changing the reflection direction of the galvano mirror 3.

However, in the case of this device, since the objective lens 4 that performs F servo and the galvano mirror 3 that performs T servo are independent, it is difficult to mount these devices with their optical axes aligned, and adjustments must be made during assembly. The work becomes complicated. In addition, the galvano mirror 3 is prone to high-frequency double resonance, and since the mirror 3 is supported by rubber or the like, there is hysteresis in the operation, which prevents accurate operation.

As a solution to the above-mentioned drawbacks, the focus coil and the tracking coil are mounted on separate bobbins, arranged in separate magnetic circuits, and the objective lens is supported so as to be slidable and rotatable about the axis. A technique for performing F servo by moving up and down and T servo by rotating was disclosed in Japanese Patent Application Laid-Open No. 55-117745.
It is disclosed in the publication No.

The present invention aims to eliminate the above-mentioned drawbacks, as well as to reduce the size of the magnetic circuit, reduce the number of components, and improve efficiency.

[Means to solve the problem]

The optical disc player of the present invention is illustrated in FIGS.
As shown in FIG. 5, in an optical disk player that detects information by condensing a light beam onto a disk 5 using an objective lens 4, a movable part consisting of an objective lens 4, a bobbin 13, etc. A support means 11 that is movable along the axis and rotatably supports the objective lens 4 at a position spaced a predetermined distance from the optical axis; A coil 14 and a plurality of rectangular coils 15 attached to this bobbin 13
a, 15b; magnetic cores 16a, 16b and a magnet 17 forming a common magnetic circuit that acts on both the first coil 14 and the second coils 15a, 15b. , this first coil 1 of these rectangular coils 15a, 15b
One of the winding parts R perpendicular to the objective lens 4 is arranged in a non-magnetic field part, a focus servo signal is applied to this first coil 14, and this movable part is moved along the optical axis of this objective lens 4 to perform focusing. The tracking servo is performed by applying a tracking servo signal to the second coils 15a and 15b and rotating this movable part.

[Effect]

According to the present invention, the objective lens 4, the holding member 11,
Flange 12, bobbin 13, coils 14, 15
Focusing servo and tracking servo are performed only with the objective lens device 4 consisting of a, 15b, etc., which simplifies the configuration and makes it easy to align the optical axes. The ivy 2 and the objective lens device 4' can be arranged in a straight line, and by integrally forming them, assembly of the device can be facilitated, and adjustments during assembly are also unnecessary. Further, according to the present invention, since one of the winding portions R (return portion R) of the rectangular coils 15a and 15b orthogonal to the coil 14 is arranged in the non-magnetic field portion, it is possible to improve the driving efficiency by the servo signal. .

〔Example〕

The present invention will be described below with reference to the drawings.

First, FIG. 2 shows a principle diagram of the objective lens device used in the present invention, where A is a sectional view, B is a top view,
C is a perspective sectional view showing the state of the winding.

In this FIG.
2, and a cylindrical bobbin 13 extending in the optical axis direction of the lens 4 is provided at the peripheral edge of the flange 12.
One end of is connected. Around this bobbin 13,
A first coil 14 wound around the bobbin 13 is provided. Furthermore, second coils 15a and 15b are provided around the bobbin 13 at positions facing each other and are wound in the optical axis direction of the lens 4.

Also, the inside of the bobbin 13 and the coils 14, 15
Magnetic cores 16a, 16b are provided on the outside of the cores 16a, 15b, and a magnet 17 is provided at a predetermined portion of the cores 16a, 16b to form a magnetic field passing through the coils 14, 15a, 15b between the cores 16a, 16b. be made into

Further, one end of a cylindrical barrel 18 extending in the optical axis direction of the lens 4 is connected to the peripheral edge of the holding member 11, and a spacer 19 is provided inside the inner magnetic core 16b, so that the position of the barrel 18 is Regulations are in place. Note that the barrel 18 and the bobbin 13 are arranged concentrically.

The lens 4 is attached to the holding member 11 so that its optical axis is spaced a predetermined distance from the central axes of the barrel 18 and bobbin 13 described above.

Therefore, in this device, when a current is passed through the coil 14, the objective lens 4, the holding member 11, the flange 12, and the bobbin 1 are moved depending on the magnitude of the current.
3. The coils 14, 15a, 15b and barrel 18 are moved as indicated by arrow a in FIG. 2A.

Furthermore, when a current is applied to the coils 15a and 15b, the objective lens 4 to the barrel 18 rotate about the center of the bobbin 13 as the rotation axis, as shown by the arrow b in FIG. 2B, depending on the magnitude of the current. be done.

In this case, since the center of the bobbin 13 and the optical axis of the objective lens 4 are separated by a predetermined distance, the optical axis of the lens 4 moves as shown by the broken line in FIG. 2B, and the optical axis is moved left and right. Ru.

That is, in this device, F servo is performed by passing current through coil 14, and coil 15
T servo can be performed by passing current through a and 15b.

Further, FIG. 3 shows the configuration of an optical disc player to which the present invention is applied.

In the figure, a light beam from a laser light source 1 is supplied through a beam splitter 2 to an objective lens device 4' having the above-described configuration. Further, the reflected light from the disk 5 is supplied to the beam splitter 2 through the objective lens device 4'.
The light is reflected by the photodetector 7 and supplied to the photodetector 7. Focusing and tracking servo signals detected by a portion of the photodetector 7 are supplied to the above-mentioned coils 14, 15a, and 15b of the objective lens device 4'.

In this way, focusing servo and tracking servo are performed in the optical disc player. According to this configuration, since two-axis servo is performed only with the objective lens device 4', the configuration is extremely simple, and It is also possible to easily match the optical axes.

Furthermore, since no galvano mirror is used, there are no problems due to multiple resonance or hysteresis.

Furthermore, since the laser light source, beam splitter, and objective lens device are arranged in a straight line, by forming them in one piece, assembly of the device becomes extremely easy, and there is no need for adjustments during assembly. Become. Furthermore, since the first coil 14 and the second coils 15a, 15b are arranged in a common magnetic circuit, it is possible to achieve miniaturization and component saving.

FIG. 4 shows an example of an objective lens device 4' according to the present invention. In this figure, coil 15a,
15b has two return parts R as shown in the figure.
It is divided into parts and arranged at angular positions of 90 degrees with respect to the driving part M, so that the whole is formed into a rectangular parallelepiped shape. In addition, at least the coil 1 of the magnetic core 16a
A notch is provided in the portion of 5a, 15b facing the return portion R.

That is, the coils 15a and 15b are constructed as shown in the perspective view of FIG. 5, and the core 16a is provided with a notch as shown by the dashed line.

Therefore, in this configuration, the coils 15a, 15
When a current is applied in the same direction to the drive unit M of the coils 15a and 15b, a force that rotates the bobbin 13 is generated between the coils 15a and 15b and the magnetic field between the magnetic cores 16a and 16b. At this time, a current in the opposite direction flows through the return portion R, but since the portion of the magnetic core 16a facing the return portion R is notched,
There is no magnetic field in the return section R, and no force is generated.
That is, since the return section R is disposed in the non-magnetic field section, it is possible to improve the drive efficiency using the servo signal.

According to this configuration, by rotating the bobbin 13, the optical axis can be moved left and right as described in FIG. 2, and the apparatus can be realized with an extremely simple configuration.

〔Effect of the invention〕

According to the present invention, the objective lens 4, the holding member 11,
Flange 12, bobbin 13, coils 14, 15
Focusing servo and tracking servo are performed only with the objective lens device 4' consisting of a, 15b, etc., which has the advantage of simplifying the configuration and making it easy to align the optical axes. 1. The beam splitter 2 and the objective lens device 4' can be arranged in a straight line, and by forming these in one piece, there is an advantage that assembly of the device can be made easier, and adjustments etc. during assembly can be made easier. There is a benefit that makes it unnecessary. Further, according to the present invention, the coil 14 of the rectangular coils 15a, 15b
Since one of the winding parts R (return part R) perpendicular to the servo signal is disposed in the non-magnetic field part, there is an advantage that driving efficiency can be improved by the servo signal.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional device, FIGS. 2 and 3 are diagrams for explaining the principle of the present invention, and FIGS. 4 and 5 are block diagrams of an example of the present invention. 1 is a laser light source, 2 is a beam splitter, 4
is an objective lens, 4' is an objective lens device, 7 is a photodetector, 14, 15a, 15b are coils, 16a,
16b is a magnetic core.

Claims (1)

[Claims] 1. An optical disk player that detects information by focusing a light beam on a disk using an objective lens, in which a movable part including the objective lens and a bobbin is movable along the optical axis of the objective lens, and the movable part includes the objective lens and the bobbin. a support means rotatably supported around a point spaced a predetermined distance from the optical axis of the objective lens; a first coil wound around the bobbin; and a plurality of rectangular shapes attached to the bobbin. a rectangular coil of the second coil, the second coil comprising a second coil, and a magnetic core and a magnet that constitute a common magnetic circuit that acts on both the first coil and the second coil; One of the winding parts perpendicular to the first coil is arranged in a non-magnetic field part, and a focus servo signal is applied to the first coil to move the movable part along the optical axis of the objective lens. A tracking servo signal is applied to the second coil to rotate the movable part about a point spaced a predetermined distance from the optical axis of the objective lens, thereby performing a tracking servo. An optical disc player characterized in that it performs the following.