JPS6245298Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a drive mechanism for optical components such as an objective lens in an optical information reading device.

An example of this type of conventional drive mechanism is the mechanism shown in FIG. In this method, internal magnetic type magnetic circuits ₄₁ to ₄₄ , each consisting of a magnet 1, a center pole 2, and a yoke 3, are arranged equidistantly on a base 5 at 90-degree intervals so that the center poles 2 are lined up on the same plane. ,
The coils 6 1 to 6 ₄ are positioned in the magnetic gap of those magnetic circuits _{4 1} to 4 ₄ , and the coils 6 ₁ to
₆₄ is integrated into a flange 7, and an objective lens 8 is attached to the center of the flange 7. In this mechanism, by applying focusing, tracking, and tangential signals to each coil ₄₁ to ₄₄ in appropriate distribution, the objective lens 8 is aligned with the optical axis as shown by arrow A in the case of focusing. In the case of tracking or tangential movement, it moves in parallel around a certain point as shown by arrows B and C. However, in this mechanism, movement in the direction perpendicular to the optical axis of the optical component, that is, in the tracking or tangential direction, is not parallel movement, but rotation, so it is adversely affected by lens aberration, etc. It was optically disadvantageous.

On the other hand, FIG. 2 shows another conventional drive mechanism, in which an internal magnetic type magnetic circuit 12 ₁ to 12 ₄ is composed of a magnet 9, a center pole 10, and a yoke 11.
are arranged on the base 13 at angular intervals of 90 degrees so that the center poles 10 face each other at the magnetic circuits 12 ₁ and 12 ₃ and also face each other at the magnetic circuits 12 ₂ and 12 ₄ , and the pole yoke 14 An external magnetic type magnetic circuit ₁₂₅ with a pole facing upward is disposed below the base 13, and four coils 17 are attached to the objective lens 15 via a flange 16.
₁ to ₁₇₄ are respectively positioned in the magnetic gaps of the magnetic circuits ₁₂₁ to ₁₂₄ , and one coil ₁₇₅ is positioned in the magnetic gap of the magnetic circuit ₁₂₅ via the flange 18. In this configuration, the coil ₁₇₅ works for focusing in the direction of arrow A, and the coils ₁₇₁ and ₁₇₃ work for focusing in the direction of arrow B.
Coils ₁₇₂ and ₁₇₄ serve for tangential tracking in the direction of arrow C. However, although this mechanism allows the objective lens 15 to move in parallel in any direction, which is optically advantageous, there is a problem because the focus drive system is placed below the objective lens 15. This results in a long beam in the optical axis direction.

An object of the present invention is to provide a drive mechanism for optical components such as an objective lens that can be miniaturized and is optically advantageous.

The present invention will be explained in detail below using examples. In FIG. 3, 20 is a base, and a pair of internal magnetic type magnetic circuits 2 are connected to the base 20.
₁₁ and ₂₁₂ are mounted such that their respective magnetic gaps are parallel to the optical axis of the objective lens 26. In addition, a pair of internal magnetic type magnetic circuits 22 ₁ and 22 ₂ are arranged perpendicularly to the arrangement of the pair of magnetic circuits 21 ₁ and 21 ₂ , and the magnetic gaps thereof are arranged in a straight line. ing. The former magnetic circuits 21 ₁ and 21 ₂ have round coils ₂₄ 1 wound around bobbins 30 ₁ and 30 ₂ attached to the flange 23 .
and 24 ₂ are located, and square coils 25 ₁ and 25 ₂ wound around bobbins 31 ₁ and 31 ₂ attached to the flange 23 are located in the magnetic gap of the latter magnetic circuits 22 ₁ and 22 ₂ . It's becoming like that. An objective lens 26 is attached to the center of this flange 23, and when the whole is assembled, this objective lens 26 is attached to the coils 24 ₁ and 24 _2.
It is arranged to be located at the center between the coils 25 ₁ and 25 _{2 and at the center between the coils 25 1 and 25 2} . Thereby, the common coil axis of the coils 25 ₁ and 25 ₂ is connected to the objective lens 26 , the flange 23 , and the coils 24 ₁ , 2
4 ₂ , 25 ₁ , and 25 ₂ can be arranged so as to pass through the center of gravity of the entire movable part, which is preferable in terms of driving characteristics. Although these movable parts are not shown, the magnetic circuits 21 ₁ , 21 ₂ , 22 ₁ , 22 ₂ and the base 20 can be moved by elastic supports having an appropriate shape.
is supported.

In this embodiment, when a current is applied to the coils 24 ₁ and 24 ₂ to apply a uniform driving force in the same direction, the objective lens 26 is moved in parallel in the focus direction shown by arrow A. Furthermore, when a current is applied to the coils ₂₅₁ and ₂₅₂ to apply a driving force in the opposite direction, the objective lens 26 is moved in parallel in the tracking direction shown by the arrow B, which is perpendicular to the direction of the arrow A. In other words,
Parallel movement is possible for both focus movement and tracking movement.

If the correction of the time axis is controlled using an electronic variable delay line such as a CCD (charge coupled device), it is possible to avoid optically disadvantageous rotation of the objective lens 26.

Although the above is an example of driving the objective lens 26, the same can be applied to a semiconductor laser pickup or the like that includes a light source and/or a light receiving element.

Furthermore, in this embodiment, the driving of the objective lens, etc. was explained using a moving coil type driving means in both the focusing direction and the tracking direction.
The present invention is not limited to this, and similar effects can be obtained even if part or all of the drive means is of a moving magnet type.

From the above, according to the present invention, linear movement can be performed in both the tracking direction and the focusing direction, which is very convenient, and since the drive system can be arranged on the same plane, the dimensions in the optical axis direction can be reduced. It is possible to make the shape smaller. Note that if driving in the tangential direction is performed by controlling the current flowing through a pair of coils parallel to the optical axis, the objective lens will be rotated, but it is not necessary to use a CCD or the like.

[Brief explanation of the drawing]

Fig. 1 a is a plan view of a conventional drive mechanism, b is a sectional view taken along line bb of a, Fig. 2 a is a plan view of another conventional drive mechanism, b is a line bb of a 3 shows a drive mechanism of an embodiment of the present invention, a is a plan view, b is a sectional view taken along line bb of a, and c is a sectional view taken along c-c of a. FIG. 4 is an exploded perspective view of the main parts of the drive mechanism. 20...Base, 21 ₁ , 21 ₂ ...Magnetic circuit, 22 ₁ , 22 ₂ ...Magnetic circuit, 23...Flange, 24 ₁ , 24 ₂ ...Coil, 25 ₁ , 25
₂ ...Coil, 26...Objective lens, 30 _1,3
0 ₂ , 31 ₁ , 31 ₂ ... bobbin.

Claims (1)

[Scope of utility model registration request] a base; an objective lens disposed at the center of the base so as to be movable vertically and horizontally; a pair of focus magnetic circuits fixed on the base parallel to the optical axis with the objective lens in between; a tracking magnetic circuit fixed on the base perpendicularly to the optical axis at an angular interval of 90 degrees with the magnetic circuit and substantially coplanar; and a focusing coil located within the magnetic gap of the focusing magnetic circuit. , a tracking coil located within the magnetic gap of the tracking magnetic circuit, and a flange attached to the upper end portion of the objective lens in the center and having the four coils attached at angular intervals of 90 degrees. A drive mechanism for optical components in an optical information reading device, characterized in that: