JPS58175145A - Optical system driving device of optical information reader - Google Patents

Abstract

PURPOSE:To improve the efficiency and to make a titled device small-sized and lightweight, by lengthening the effective line length of a coil and narrowing the gap of a magnetic circuit part. CONSTITUTION:A magnetic member 7 consisting of ferromagnetic materials attached to an optical system 9 as one body is supported movably in parallel with a direction (Y direction) vertical to the optical axis of an optical system 1, and movable coils 2a and 2b are wound, and magnetic circuit parts 8a and 8b provided to interpose the magnetic member 7 consist of magnets 9 and a pair of yokes 10 fixed to both end faces of each of these magnets 9 and generate magnetic fluxes in opposite directions interlinked to coils 2a and 2b. By this constitution, magnetic fluxes are interlinked to coils 2a and 2b existing in the magnetic gap to form a closed loop through the magnetic member 7; and when a current is flowed to coils 2a and 2b, an upward force is generated, and the optical system 1 is moved upward in parallel, and optical system 1 is moved in the reverse direction in parallel when the direction of the current is inverted. Consequently, this movement direction is allowed to correspond to the tracking direction in an optical information reader, and a current corresponding to a tracking error signal is flowed to coils 2a and 2b, thereby correcting the tracking error in the optical system 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical system driving device in an optical information reading device, and more particularly to a moving coil type driving device that drives an optical system in a direction perpendicular to its optical axis.

Conventionally, there have been devices of this type as shown in FIGS. 1 and 2. In Figures 1 and 2, 1 is an optical system including an objective lens, etc., and 2a and 2b are attached to the optical system l so as to be positioned around an axis Y perpendicular to the optical axis X of the optical system. The rectangular cylindrical coils 3a and 3b are magnetic circuit parts that generate magnetic flux that interlinks with the coils 2a and 2b.
, 2b and the magnetic circuit sections 3a, 3b constitute means for driving the optical system 1 in the axis Y direction. Furthermore,
The optical system 1 is driven in the optical axis X direction by a cylindrical coil 4 attached to the optical system 1 so as to be located around the optical axis The means are configured. Optical system l is elastic support 6a
, 6b are supported so as to be movable in parallel in the optical axis X direction and the axis Y direction.

In the optical information reading device, the axis Y direction is made to correspond to the radial direction of the disk, that is, the tracking direction (or the tangential direction of the recording track of the disk, that is, the tangential direction), and the detected positional tracking error signal (or tangential direction) is detected by some method. Tracking servo (or tangential servo) is performed by passing a current through the coils 2a, ]) based on the mechanical error signal). Further, focus servo is performed by passing a current through the coil 4 based on the focus error signal.

As described above, in the conventional optical system drive device, the yokes of the magnetic circuit sections 3a and 3b are located inside the rectangular cylindrical coils 2a and 2b. Gap t for the maximum stroke driving in the direction
Since it is necessary to provide each coil between the yoke and the opposing surface of the yoke, the effective wire length of the coil that faces the yoke and can contribute to the generation of driving force is short, resulting in poor efficiency. There are still coils 2a and 2a between the yokes and cores of the magnetic circuit parts 3a and 3b.
Since 2b is provided for movement in the axis Y direction, the gap between the yoke and the core must be widened, which also has the disadvantage that the magnetic flux density interlinking with the coil 2a + 2b p is small. .

An object of the present invention is to provide an optical system drive device for an optical information reading device that can increase efficiency and reduce size and weight by increasing the effective wire length of the coil and narrowing the gap in the magnetic circuit section. do.

The optical system driving device according to the present invention includes a magnetic member that is integrally movable with the optical system and movable in a direction perpendicular to the optical axis of the optical system, and a movable coil is wound around the magnetic member. The structure includes at least one set of magnetic circuit sections that generate magnetic flux that interlinks with the coil.

Embodiments of the present invention will be described in detail below based on the drawings.

FIG. 3 is a schematic perspective view showing one embodiment of the present invention, in which parts equivalent to those in FIG. 1 are designated by the same reference numerals. In FIG. 3, 7 is a magnetic member made of a ferromagnetic material that is integrally attached to the optical system 1, and is supported by an elastic support (not shown) in a direction perpendicular to the optical axis of the optical system 1 (Y direction). It is supported so that it can be moved in parallel. Moving coils 2a and 2b are wound around the magnetic member 7, and two sets of magnetic circuit sections 8a and 8b are provided with the magnetic member 7 in between. The magnetic circuit parts 8a and 8b each consist of a magnet 9 and a pair of yokes 10 fixed to both end faces of the magnet 9, and generate magnetic fluxes in mutually opposite directions that interlink with the coils 2a and 2b. . 11 is a magnetic circuit section 8a;
This is a fixing base for fixing 8b.

In such a configuration, when the magnetic circuit parts 8a and 8b are arranged with the polarity shown in FIG. 4, for example, the magnetic flux interlinks with the coils 2a and 2b existing in the magnetic gap, and passes through the magnetic member 7 to form the closed loop shown in the figure. form. and coil 2a,
When a current is applied to the coils 2b in the direction shown in the figure, for example, a force in the upward direction in the figure is generated in the coils 2a and 2b due to electromagnetic interaction, so that the optical system 1 is translated in the same direction.

By reversing the direction of the current flowing through the coils 2a and 2b, the optical system 1 is translated in the opposite direction (downward in the figure). Therefore, this moving direction (Y direction) is the tracking direction (or tangential direction) in the optical information reading device.
By making current corresponding to the tracking error signal (or tangent/kill error signal) flow through the coils 2a and 2b, the optical system 1 can completely correct the tracking error (or tangent error).

In addition, in the above embodiment, a coil is provided on both sides of the optical system 1 in the Y direction, and two sets of magnetic circuit sections are provided, but one of the coils or the magnetic circuit section may be omitted. is also possible.

As detailed above, according to the present invention, a magnetic member is provided integrally with an optical system and movable in a direction perpendicular to the optical axis of the optical system, and a moving coil is wound around this magnetic member. ,
At least one magnetic flux generating magnetic flux that interlinks with this moving coil.
Since the structure is equipped with two sets of magnetic circuits, unlike conventional devices, a movable body (yoke) is not inserted inside the coil, so the size of the coil can be determined regardless of the stroke in the focus direction. The effective wire length of the coil that exists in the coil and can contribute to the generation of driving force can be increased, and efficiency can therefore be improved. Furthermore, since the coil is directly wound around the magnetic member, the magnetic gap can be narrowed, so leakage magnetic flux is reduced, and the density of magnetic flux interlinking with the coil can be increased. Furthermore, since the yoke has a simple shape, processing costs are low and it is easy to fix to the magnet.

[Brief explanation of the drawing]

Figure 1 is a plan view showing the conventional example, Figure 2 is the A7A of Figure 1.
A line sectional view, FIG. 3 is a schematic oblique view showing one embodiment of the present invention, and FIG. 4 is a diagram showing lines of magnetic force in a magnetic circuit section. Explanation of symbols of main parts 1...Optical system 2a, 2b, 4.
...Coil 3a+3b, 8a, 8b...Magnetic circuit section
7...Magnetic member applicant / Gionia Video Co., Ltd. agent Patent attorney Hikoizumi Fujimura Moto

Claims (2)

[Claims] (1) An optical system driving device that drives an optical system for irradiating a spot light for information reading onto the recording surface of a recording medium in a direction perpendicular to the optical axis of the optical system, and is integrated with the optical system. a magnetic member disposed so as to be movable vertically and in the perpendicular direction; a moving coil wound around the magnetic member; and at least one set of magnetic circuit units that generate magnetic flux interlinking with the moving coil. An optical system drive device comprising: (2) The optical system drive device according to claim 1, characterized in that two sets of the magnetic circuit portions are provided so as to sandwich the magnetic member, face each other, and generate magnetic fluxes in opposite directions. .