JPH0728582Y2 - Optical pickup device - Google Patents

Description

The present invention relates to an optical pickup device for positioning a light beam on a recording track formed on an optical storage medium such as an optical disk.

[Prior Art] In recent years, an optical disk storage device has been proposed which uses an optical disk having an optical storage medium formed in a disk shape as the storage medium. In this optical disc, a recording track having a fine structure having a track width of about 1 μm and a track pitch of about 2 μm is formed on its data storage surface, and the storage track is irradiated with a laser beam having a spot diameter of about 1 μm. To do.

Then, while rotating the optical disc, the intensity of the laser beam is modulated in accordance with the data to be recorded to store the data, and the fluctuation of the level of the laser beam reflected from the data storage surface is detected. The data stored in is being played.

In this way, the portion where the laser beam follows the recording track and the spot diameter is narrowed to a predetermined size is
This is an optical pickup, and a schematic configuration example thereof is shown in FIG.

In the figure, the laser light output from the semiconductor laser device 1 is converted into parallel light by the coupling lens 2, transmitted through the polarization beam splitter 3, and polarized by the 1/4 wavelength plate 4, and then the objective lens. The image is focused on the recording track of the optical disk 6 by the diaphragm 5.

The reflected light from the optical disk 6 is converted into parallel light again through the objective lens 5, and then further polarized by the 1/4 wavelength plate 4, thereby being reflected by the polarization beam splitter 3 and by the lens 7. An image is formed on the four-division light receiving element 8.

Further, the objective lens 5 is provided with a tracking mechanism for positioning the objective lens 5 in the radial direction of the optical disc 6 and a focusing mechanism for focusing. The tracking mechanism and the focusing mechanism will be collectively referred to as an objective lens moving mechanism hereinafter.

Then, the servo control unit (not shown) detects the position error and the focus error of the laser beam on the recording track based on the output signal of the four-division light receiving element 8, and the tracking mechanism and By controlling the focusing mechanism, the objective lens 5 is moved in a direction to reduce the positional deviation and the focal deviation of the laser beam on the recording track. Further, the recording data is taken out from the output signal of the 4-division light receiving element 8.

As the focusing mechanism attached to the objective lens 5, generally used is a lens holder that supports the objective lens 5 that reciprocates in the focusing direction by a linear motor, a voice coil, or the like. As the tracking mechanism, there is used a linear motor, a voice coil, or the like that reciprocates in an arc shape in the tracking direction including the focusing mechanism.

In such a tracking mechanism, conventionally, as shown in FIG. 4, for example, a shaft 10 serving as the center of the circular movement is supported.

That is, an inverted L-shaped support member 12 is provided on the base member 11 of the objective lens moving mechanism, a bearing 13 made of artificial jewel is fitted to the support member 12, and the bearing 13 is made of artificial jewel so as to face the bearing 13. The bearing holding member 15 in which the bearing 14 is fitted and arranged is fitted to the base member 11, and both ends of the shaft 10 are received by the bearings 13 and 14. Further, the bearing holding member 15 is biased upward by the leaf spring 16 arranged on the back surface of the base member 11.

[Problems to be Solved by the Invention] However, such a conventional device has the following disadvantages.

That is, in order to make the rotation of the shaft 10 smoothly, in order to minimize the frictional force between the shaft 10 and the bearings 13, 14, the shaft 1
The diameter of the mounting holes of the bearings 13 and 14 into which the tip of 0 is inserted is extremely small, and therefore the tip of the shaft 10 falls off from the bearings 13 and 14 when an impact or the like is applied from the outside. That caused the inconvenience.

Also, due to the friction between the tip of the shaft 10 and the bearings 13 and 14,
There is also a disadvantage that vibration is generated at the contact portion between the tip of the shaft 10 and the bearings 13 and 14, which adversely affects the control system of the tracking mechanism and the control system of the focusing mechanism.

The present invention has been made in order to eliminate the disadvantages of the prior art, and an object thereof is to provide an optical pickup device capable of preventing the shaft of the tracking mechanism from falling off and generating vibration.

[Means for Solving the Problems] In order to achieve this object, the present invention linearly moves an objective lens for focusing a light beam on a recording track formed on an optical storage medium in the focal direction thereof. In an optical pickup device equipped with an objective lens moving mechanism for circularly moving in a tracking direction to position a light beam on a recording track, two bearing members for receiving both ends of a rotating shaft of the objective lens moving mechanism, and the rotating shaft. Two sleeve members made of a soft elastic material and arranged between both ends of the bearing member, and a biasing means for applying a biasing force acting from the outside of the bearing member in a direction of compressing in the axial direction of the rotating shaft. Be prepared.

In addition, the objective lens that forms the light beam on the recording track formed on the optical storage medium is moved linearly in the focal direction and circularly moved in the tracking direction to position the light beam on the recording track. In an optical pickup device including a mechanism, both ends of a rotary shaft of the objective lens moving mechanism are formed in a conical shape, and a concentric frame that stands up outside the rotary shaft is formed around a bearing member that receives the both ends. A member is formed, and the gap between the outer surface of the rotary shaft and the frame member is set to be smaller than the diameter of the hole of the bearing member into which the rotary shaft is inserted.

[Operation] Therefore, even if an external force acts on the optical pickup device and vibrates, the vibration is absorbed by the sleeve member, so that the rotating shaft is prevented from falling off from the bearing member.
Further, since the urging force that the urging means acts to prevent the falling-off can be reduced, the frictional force between the rotating shaft and the bearing member can be reduced, thereby suppressing the generation of unnecessary vibration. it can.

Embodiments Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a structural example of an optical pickup device according to an embodiment of the present invention, in particular, a tracking mechanism for moving an objective lens for focusing a laser beam in a tracking direction and a focusing mechanism for moving it in a focusing direction. There is. Note that, hereinafter, these mechanisms are generically referred to as an objective lens moving mechanism. The overall structure of the optical pickup device is similar to the conventional one shown in FIG.

In the figure, the objective lens 5 is housed in a lens holder 20, and the lens holder 20 has focus bobbins 21 and 22 around which a drive coil that constitutes a linear motor that is a drive source of a focusing mechanism is wound, and Track bobbins 23, 24 around which a drive coil that constitutes a linear motor that is a drive source of the tracking mechanism is wound are attached.

The focus bobbins 21 and 22 are inserted with the yokes of the magnetic circuit members 26 and 27 formed integrally with the base 25, and the track bobbins 23 and 24 are formed integrally with the base 25. The yokes of the magnetic circuit members 28 and 29 are inserted.

Further, the lens holder 20 includes two sets of parallel leaf springs 31, 32, 3
It is elastically supported by the rotary supporter 35 by 3,34. The leaf spring 32 facing the leaf spring 31 is in a position not visible in the figure.

The rotary supporter 35 is rotatably supported between a base 23 and a support member 36 standing upright in an inverted L shape from the base 23, and the state is shown in FIG.

At the upper and lower ends of the part corresponding to the center of rotation of the rotary supporter 35, there are seated pins 37, 3 with conical tips.
The bearings 8 are fixed to each other, and the tips of the pins 38 fixed to the upper end are fitted and arranged in the support member 36.
The tip of the pin 38 fixed to the mounting hole of 39 and fixed to the lower end is fitted to the mounting hole of the bearing 41 housed in the holder 40. The bearings 39 and 41 are made of artificial jewelry.

The holder 40 is inserted into the hole 25a formed in the base 25 so as to face the ball bearing 39 with a slight gap, and the leaf spring 42 attached to the lower surface of the base 25.
A biasing force is given upward by.

The pins 37 and 38 are made of a soft elastic material such as butyl rubber or silicon rubber, and are inserted into the substantially drum-shaped sleeves 43 and 44 having a small outer diameter in the central portion and the bearings 39 and 38. , 41, the both end surfaces of the sleeve 43 are on the seat surface of the pin 37 and the lower surface of the bearing 39, and the sleeve 44 is
Both end faces are attached to the seating surface of the pin 38 and the upper surface of the bearing 41 by adhesion or heat welding, respectively.

The light emitting diode 46 attached to the rotary supporter 35 via the U-shaped holding member 45, and the base.
A semiconductor position detecting element 48 attached to 25 via a supporting member 47 is for detecting the displacement amount of the objective lens 5 in the tracking direction.

With the above configuration, when the drive current is supplied to the drive coil wound around the focus bobbins 21 and 22, the polarity (direction)
And the lens holder 20 moves in the focusing direction according to the strength, and thereby the position of the objective lens 5 in the focusing direction is determined. Also, truck bobbin 2
When a drive current is supplied to the drive coil wound around 3,24, the pin 3 of the rotary supporter 35 is rotated according to its polarity and strength.
The lens holder 20 rotates in the tracking direction about 7, 39, and thereby the position of the objective lens 5 in the tracking direction is determined.

In this way, the objective lens 5 is moved in the focusing direction and the tracking direction, respectively.

When the objective lens 5 is moved in this manner, the vibrations caused by friction between the tips of the pins 37 and 38 and the bearings 39 and 41 are absorbed by the sleeves 43 and 44.

Further, since the sleeves 43 and 44 connect the bearings 39 and 41 and the pins 37 and 38, respectively, the pins 37 and 38 can be removed from the bearings 39 and 41 even if an external impact is applied to the optical pickup device. Is prevented.

Therefore, since the biasing force of the leaf spring 42 can be set small, the frictional force between the pins 37, 38 and the bearings 39, 41 becomes small,
The driving force required for the tracking mechanism can be reduced. That is, it becomes easy to reduce the size of the optical pickup device.

The sleeves 43 and 44 are formed in a drum shape with a reduced thickness in the center so as not to hinder the rotation of the rotary supporter 35. The shapes of 43 and 44 are not limited to this.

FIG. 3 shows a rotary supporter 35 according to another embodiment of the present invention.
It shows the support mechanism of. In the figure, the same parts as those in FIG. 2 and corresponding parts are designated by the same reference numerals.

In the figure, the bearing 39 is accommodated in a hole 45 formed by cutting the support member 36 so as to have a diameter slightly larger than the diameter of the pin 37. Here, the diameter of the hole 45 is equal to the diameter of the pin 37,
It is set to a value obtained by adding a value smaller than the diameter dimension of the bearing hole 39a of the bearing 39.

Further, the bearing 41 is accommodated in a hole 46 formed by cutting the holder 40 so as to have a diameter slightly larger than the diameter of the pin 38. Here, the diameter dimension of the hole 46 is the same as the diameter of the pin 38, and the bearing 41
It is set to a value obtained by adding a value smaller than the diameter dimension of the bearing hole 41a.

The holes 45 and 46 are filled with oils 47 and 48 for reducing friction.

With the above configuration, when external vibration is applied to the optical pickup device, the rotation supporter resists the biasing force of the leaf spring 42.
The pin 37 of 35 moves in the direction of falling from the bearing hole 39a of the bearing 39.

At this time, as shown in FIG. 4, the outer peripheral surface of the pin 37 has a hole 45.
It is forbidden to move the pin 37 further in the falling direction by contacting the side surface of the pin 37.

Further, due to the action of the biasing force of the leaf spring 42, the pin 37 moves from that position in the direction in which it is inserted into the bearing hole 39a, whereby the pin 37 returns to the mode in which it is inserted into the bearing hole 39a.

In this way, the pin 37 is prevented from falling off when an external force is applied, and the pin 37 returns to the original position. Further, the drop prevention and the return to the original position also act on the pin 38 in the same manner.

Further, since the biasing force of the leaf spring 42 can be set to a smaller value, the vibration generated between the pins 37 and 38 and the bearings 39 and 41 can be suppressed.

In this embodiment, the side surfaces of the holes 45 and 46 receive the outer peripheral surfaces of the pins 37 and 38 to prevent the pins from falling off.However, the bearings 39 and 41 are raised around the same diameter as the holes 45 and 46. Even if the frame member is provided, the same effect of preventing the drop as the holes 45 and 46 can be obtained.

By the way, in each of the above-described embodiments, the bearing made of artificial jewelry is used, but the present invention can be applied to the case where a bearing such as a ball bearing is used as the bearing.

As described above, according to the present invention, the sleeve member made of a soft elastic material is provided between the bearing member that receives both ends of the rotary shaft of the objective lens moving mechanism and the both ends of the rotary shaft. Since it is provided with an urging means for applying an urging force acting from the outside of the bearing member to the axial direction of the rotary shaft, the generation of vibration between the rotary shaft and the bearing member is suppressed. It is possible to obtain the effect that the rotating shaft can be prevented from falling off the bearing member. Further, both ends of the rotary shaft of the objective lens moving mechanism are formed in a conical shape, and a concentric frame member standing outside the rotary shaft is formed around a bearing member that receives the both ends. Since the gap between the frame member and the frame member is set to a size smaller than the diameter of the hole of the bearing member into which the rotary shaft is inserted, there is an advantage that the rotary shaft can be prevented from falling off from the bearing member.

[Brief description of drawings]

FIG. 1 is a perspective view showing an objective lens moving mechanism according to an embodiment of the present invention, FIG. 2 is a partial sectional view showing an example of a support mechanism for a rotary supporter, and FIG. 3 is another support mechanism for a rotary supporter. FIG. 4 is a schematic sectional view for explaining the operation of the mechanism of FIG. 3, FIG. 5 is a schematic diagram showing an example of the configuration of the optical pickup, and FIG. 6 is a schematic view of the objective lens moving mechanism. It is a fragmentary sectional view showing the conventional example of the mode of attachment of a shaft. 5 ... Objective lens, 20 ... Lens holder, 21,22 ... Focus bobbin, 23,24 ... Track bobbin, 25 ... Base, 25a ... Hole, 26,27,28,29 ... Magnetic circuit Material, 3
1,32,33,34,42 …… Leaf spring, 35 …… Rotation supporter, 36…
… Supporting members, 37, 38… Pins, 39, 41… Bearings, 39a, 41a
...... Bearing hole, 40 …… Holder, 43,44 …… Sleeve, 45,46
……hole.

Claims (2)

[Scope of utility model registration request] 1. An objective lens for focusing a light beam on a recording track formed on an optical storage medium is linearly moved in the focal direction and is circularly moved in the tracking direction to position the light beam on the recording track. In an optical pickup device having an objective lens moving mechanism, two bearing members for receiving both ends of a rotary shaft of the objective lens moving mechanism and a soft elastic material disposed between the two end parts of the rotary shaft are used. An optical pickup device comprising: one sleeve member; and an urging means for applying an urging force that acts from the outside of the bearing member in a direction of axially compressing the rotating shaft. 2. An objective lens for focusing a light beam on a recording track formed on an optical storage medium is linearly moved in its focal direction and circularly moved in the tracking direction to position the light beam on the recording track. In an optical pickup device equipped with an objective lens moving mechanism, both ends of a rotary shaft of the objective lens moving mechanism are formed in a conical shape, and a concentric circle rising outside the rotary shaft is formed around a bearing member that receives the both ends. -Shaped frame member is formed, the gap between the outer surface of the rotating shaft and the frame member,
An optical pickup device, which is set to a size smaller than a diameter of a hole of the bearing member into which the rotary shaft is inserted.