JPH0135295Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to an objective lens support mechanism in an optical information reading device.

BACKGROUND ART In an optical information reading device, an information recording medium such as a video disk or a digital audio disk has minute pits (dents) formed in the form of spiral tracks on its surface in accordance with information signals. Therefore, the information signal is recorded. When reproducing such a disk, the disk is rotated at a predetermined number of revolutions while a spot light is irradiated onto the track, and changes in the intensity of the reflected light or transmitted light are converted into electrical signals, which are then used as the original information signals. It is something to be regenerated.

In the reproduction of this disk, the irradiated light must be accurately focused on the recording surface of the disk, which requires position control in the direction perpendicular to the recording surface of the disk, that is, the focus direction (focus servo). Furthermore, since the irradiation light must always accurately track the recording track, it is necessary to control the irradiation light in the radial direction of the disk, that is, in the tracking direction (tracking servo).

For this reason, the pickup device of the information reading device requires a support mechanism that supports the objective lens movably in the focus direction and the tracking direction to irradiate the recording surface of the disk with spot light for information reading, and a focus error signal. and a drive mechanism that drives the objective lens in the focus direction and the tracking direction in accordance with the tracking error signal.

Various types of the above-mentioned support mechanisms have been proposed in the past.
An example is shown in FIG.

In the first example of the support mechanism shown in FIG. 1, a support plate 1 made of Baba steel with one end fixed
is provided, and an objective lens (not shown) is attached to the free end of the support plate. Also,
A vibration absorbing material 2 made of rubber or the like is adhered to the main surface of the support plate 1. Further, the objective lens is driven by an electromagnetic drive means (not shown).

FIG. 2 shows a second example of the above-mentioned support mechanism. Note that the same reference numerals are used for parts having the same configuration as the support mechanism shown in FIG. 1, and the parts other than those described below are configured in exactly the same manner as the support mechanism and will not be described in detail.

As shown in FIG. 2, a damping plate 3 that covers almost the entire surface of the vibration absorbing material 2 is attached to the upper surface of the vibration absorbing material 2, so that the damping plate 3 is sandwiched between the vibration absorbing material 2 and the support plate 1. .

For example, in the support mechanism of the first example above, when the objective lens (not shown) is driven in the focusing direction (or tracking direction), the support plate 1 and the vibration absorbing material 2 normally bend as shown in FIG. but,
When the driving frequency matches a predetermined natural frequency determined by the longitudinal spring constant of the support plate 1 and the shape and mass of the objective lens, the support plate 1 resonates.
There is a problem in that so-called parasitic resonance occurs. The vibration absorbing material 2 is provided to prevent this resonance. That is, as the vibration absorbing material 2 bends as described above, internal frictional heat is generated due to the deformation, and the energy that causes the resonance is released as thermal energy.

Also in the support mechanism of the second example shown in FIG.
When the objective lens is driven, it undergoes a similar deformation as described above, and the vibration absorbing material 2 releases energy to suppress resonance. However, the vibration absorbing material 2 is the support plate 1 and the brake plate 3.
Since the vibration absorbing material 2 is sandwiched in a sandwich-like manner between It increases.

In both the support mechanisms of the first example and the second example, the vibration absorbing material 2 effectively exerts a vibration absorbing action against deformation of the support plate 1 in a direction perpendicular to the main surface, and resonance is suppressed. However, if torsional deformation as shown in FIG. 4 occurs for some reason during driving, the vibration absorbing material 2 cannot absorb vibrations sufficiently. As a result, a problem arises in that parasitic resonance occurs.

Summary of the invention The present invention was made in view of the above points, and its purpose is to create an objective lens support mechanism that does not generate parasitic resonance even when the support plate is torsionally deformed. The goal is to provide the following.

The objective lens support mechanism according to the present invention includes a cantilever-like leaf spring that supports the objective lens at its free end, and a vibration absorbing material attached to the main surface of the leaf spring. It is characterized in that a long hole is formed that is elongated in the direction from one end of the spring to the other end.

Embodiment Hereinafter, an objective lens support mechanism according to an embodiment of the present invention will be described with reference to FIGS. 5 and 6.

As shown in FIG. 5, a rectangular plate spring or support plate 1 is formed by punching a spring steel plate.
1 is fixed at one end to the base member 12. An objective lens 13 is attached to the free end of the support plate 11 for irradiating a recording surface of a recording medium such as a video disk (not shown) with laser spot light. The objective lens 13 is driven by an electromagnetic drive means (not shown), for example, in a direction perpendicular to the recording surface of the video disk, that is, in a focus direction Z, in response to a focus error signal.

As is clear from FIG. 6, a vibration absorbing material 14 made of a viscoelastic material such as rubber and formed into a rectangular plate shape is adhered to the upper main surface of the support plate 11. Further, a rectangular plate-shaped braking member 15 made of aluminum or the like and processed to be somewhat thinner than the support plate 11 is attached to the upper surface of the vibration absorbing member 14 .

For example, two elongated holes 11a are formed approximately at the center of the main surface of the support plate 11 and extend as long as possible in the approximately longitudinal direction of the support plate.

Next, the vibration absorption effect when the support plate 11 causes torsional vibration in the objective lens support mechanism having the above-mentioned configuration will be explained with reference to FIG. 7 as well.
Note that the vibration absorption effect during so-called simple bending, in which the support plate 11, the vibration absorbing material 14, and the braking member 15 are each bent into a cantilever shape as the objective lens 13 is driven in the focus direction Z, is already clear. It will not be detailed here.

When the objective lens 13 is driven, the support plate 11, the vibration absorbing material 14, and the braking member 1 may be damaged due to some reason.
5 undergoes torsional deformation as shown in Figure 7,
The side pieces 11b and the center piece 1 of the support plate 11, which formed the same plane as shown in FIG. 6 before deformation,
1c are shifted from each other in a stepwise manner in a direction substantially perpendicular to the main surface of the support plate 11. Along with that,
The vibration absorbing material 14 undergoes shearing deformation in the direction of this shift. Therefore, internal frictional heat is generated due to shear deformation, and the energy that tends to cause resonance is released as thermal energy.

Although the embodiment shows a case in which the objective lens is movably supported in the focusing direction, the present invention is not limited to this, and a support mechanism that supports the objective lens movably in the tracking direction may be used.

Effects As detailed above, the objective lens support mechanism in the optical information reading device according to the present invention has the following effects:
It has a cantilever-like leaf spring that supports the objective lens at its free end, and a vibration absorbing material attached to the main surface of the leaf spring. A long hole is formed which is elongated in the direction toward.

Because of this configuration, shearing deformation occurs in the vibration absorbing material due to torsional vibration of the leaf spring, and the resulting internal friction damps the vibration of the leaf spring, thereby preventing parasitic resonance from occurring.

[Brief explanation of the drawing]

FIGS. 1 and 2 are diagrams showing the main parts of a conventional objective lens support mechanism, FIGS. 3 and 4 are diagrams for explaining the operation of the support mechanism, and FIGS. A plan view and a vertical sectional view of the objective lens support mechanism according to the invention, and FIG. 7 are diagrams for explaining the operation of the support mechanism. Explanation of symbols of main parts, 11...Support plate, 11
a... Long hole, 13... Objective lens, 14... Vibration absorbing material, 15... Braking member.

Claims (1)

[Scope of utility model registration request] A plate spring supporting an objective lens at one end and fixed at the other end for irradiating a spot light onto a recording surface of a recording medium, and a vibration absorbing material attached to a main surface of the plate spring. An objective lens support mechanism in an optical information reading device, wherein a long hole is formed in the main surface and is elongated in a direction from the one end to the other end.