JPS60121541A - Objective lens driver for optical information recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve the productivity of the titled objective lens driver by positioning a track direction drive coil of said driver at a place near to a magnetic circuit where the magnetic flux of the magnetic circuit is cut and therefore simplifying the form of the drive coil. CONSTITUTION:A track direction coil 11 is not bent, and only two groups are fixed to both side surfaces of a focus direction coil 10. The vertical parts 11v at both sides are positioned close to right and left magnetic circuit 12. In other words, the part 11v of the coil 11 is set at a position where a magnetic flux delivered from a permanent magnet 14 and entered into a leg part 15a of a U- shaped yoke 15 is cut off. The coil 10 forms a magnetic closed circuit at an area between the circuit 12 and the coil 10. While the coil 11 forms a magnetic open circuit. Then a magnetic member 20 fixed to a slider 3 is added to improve the density of the magnetic flux which affects the coil 11.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for recording information on optical recording disks, which are becoming widely used for video, audio, etc., or for reading recorded information by directing a laser beam onto the disk. The present invention relates to an objective lens driving device for converging an objective lens.

Taking reading as an example, this type of optical information recording/reproducing device irradiates an optical recording disk with an information reading laser beam focused by an objective lens, and the reflected light is recorded on the disk. It reads information, and the objective lens is mounted on a slider that moves in the track direction (radial direction) of the disk. In order to read information accurately, the objective lens must be able to move the focus adjustment stop in the optical axis direction and make fine adjustments in the track direction, that is, in the approximately radial direction of the disk, on this slider.

FIGS. 1 to 4 show conventional objective lens driving devices having this function.

In FIGS. 1 to 4, l is an optical recording disk that is driven to rotate around a rotation axis 1a, and this disk 1
Slider 3 is attached to guide rail 2 provided in the radial direction of
is slidably supported. The objective lens 4 is fitted and supported by an objective lens support unit 5, and this support unit 5 is supported on the slider 3 via a leaf spring 6.7 that allows movement in the focus direction and the track direction. That is, one end of the leaf spring 6 is fixed to the slider 3, the other end of the leaf spring 6 is fixed to the relay member 8, and the free end of the leaf spring 7, which has one end fixed to the relay member 8, is provided with the above-mentioned support. Unit 5 is fixed. The leaf spring 6 is deformable in the focus direction F, and the leaf spring 7 is deformable in the track direction T, so that the combination of the two allows the objective lens 4 to be displaced in both directions. The optical axis of the objective lens 4 is perpendicular to the recording disk 1, and the optical axis is guided through a Rade light source and a beam splitter (consisting of a combination of a polarizing beam splitter and a quarter-wave plate, or a half mirror) (not shown). The information reading laser beam is focused onto the disk 1.

The reflected light reflected by the Dinuku l passes through the objective lens 4 again, is split by the beam splitter, and enters the light receiving element ■'.
This light receiving element reads out the signal as a signal.

The objective lens support unit 5 is made of a substantially rectangular coil.
It has a plate 9, and a focus direction drive coil 10 and a track direction drive coil 11 are fixed to this fixed plate 9')i! has been done. The track direction drive coil 11 is divided into four parts 1 and fixed to the focus direction drive coil 10, and the focus direction drive coil 10 and the track direction drive coil 11 are arranged in the gap 13 of the magnetic circuit 12 fixed to the slider 3. It is located in The magnetic circuit 12 includes a permanent magnet 14 and a U-shaped yoke 15 made of a magnetic material fixed to the permanent magnet 14. The yoke 15 constitutes a gap 13 parallel to the optical axis of the objective lens 4.

As shown in FIG. 4, the focus direction drive coil 1O is wound into a substantially rectangular shape around the optical axis of the objective lens 40 in accordance with the shape of the fixed plate 9, and includes a track direction drive coil 11 divided into four groups. is this focus direction drive coil 1
It is bent at a substantially right angle and attached to the corner part of 0. The track direction drive coil 11 includes two groups of track direction drive coils ll located within the same gap 13.
The wires are wired so that current flows in the same direction in the vertical portion 11v, and each of the two groups of track direction drive coils 11 located in the opposing gap 13 is wired so that current flows in the same direction in the vertical portion 11v. The wires are wired so that current flows in the same direction. The permanent magnets 14 are magnetized so that the objective lens 4 side has the same polarity. In other words, two permanent magnets (d7.41J 4 have both N
(In the illustrated example, both sides of the objective lens 4 are N poles.) Note that the arrow in the figure indicates the direction of magnetic flux.

1. In the conventional device having the configuration described above, when a current is applied to the focus direction drive coil 10, this focus direction drive coil l
O is located within the gaps 1' and 3 of the pair of left and right magnetic circuits 12, and the direction of the magnetic flux generated within these left and right gaps 1' and 3 is both toward the objective lens 4 side, so the left and right magnetic circuits 12 are The focus direction drive coil 10 receives a force in the focus direction F due to the current flowing through the focus direction drive coil 10 in the opposite direction within the magnetic circuit 12 . That is, the objective lens 4 is driven in the focus direction F mainly by bending the leaf spring 6. I was also divided into four groups.
・When a current is passed through the rack direction drive coil 11, 4 nY
The directions of the currents are the same in both gaps 1 and 3 as described above, and are opposite to each other between the left and right gaps 13, so the track direction drive coil 11 receives a force in the track direction T.

That is, the objective lens 4 is driven in the trunk direction T mainly by bending the leaf spring 7.

However, in this conventional device, the track direction drive coil 11
The focus direction drive coil IO is bent to approximately 90".
It is necessary to adhesively fix the track direction drive coil 11 to the corner part of the track direction drive coil 11, which requires a step of bending it at 90 degrees, which results in poor Ir resistance, and accidents such as wire breakage may occur during the bending or bonding process. Cheap. Furthermore, since four groups of track direction drive coils ti are used, there are problems in that the weight is large and the drive sensitivity is poor.

The present invention has been made based on this problem awareness, and as a result of research, the track direction drive coil 11 does not necessarily need to be located within the gap 13 of the magnetic circuit 12, but is located at a position where the magnetic flux generated in the magnetic circuit can be cut. This was done based on the knowledge that driving in the track direction is also possible if installed at right angles.

In other words, the conventional device is constructed on the premise that it is essential to position the track direction drive coil 11 within the gap 13 of the magnetic circuit 12. The directional drive coil 11 is one of the magnetic circuits 12! →, it is possible to drive in the track direction simply by placing it in the vicinity of the knob 13, and it is not necessarily necessary to place it within the camp 13 ()°.

Therefore, the present invention provides a fixed structure for the objective lens support member.
The track direction driving coil is disposed outside the gap of the yoke of the magnetic circuit fixed on the slider and at a position where the magnetic flux of the magnetic circuit is cut off.

The invention will now be described with reference to the illustrated embodiments. No.! Figure 5 to Figure ftS7 show the first embodiment of the present invention.
The same components as those of the conventional device mentioned above have the same designations. This embodiment differs from the conventional apparatus in the shape and position of the track direction drive coil 11, and the manner in which the objective lens 4 is supported. The track direction drive coil 11 is not bent unlike the conventional device, and only the two groups are fixed to both sides of the focus direction drive coil lO, and the vertical portions 11v on both sides are connected to the left and right magnetic circuits 11. It is arranged so that it is located in the vicinity of. Near the magnetic circuit 12 means that the vertical portion 11v of the track direction drive coil 11 is arranged at a position where the magnetic flux exiting from the permanent magnet 14 and entering the leg portion 15a of the U-shaped yoke 15 is cut. The vertical portion 11v is orthogonal to the magnetic flux. On the other hand, the focus direction drive coil 10, which is wound in a rectangular shape around the optical axis of the objective lens 4, is located within the gap 13 of the magnetic circuit 12, as in the conventional device. In other words, the focus direction drive coil IO constitutes a magnetic closed circuit with the magnetic circuit 12, and the track direction drive coil 11 constitutes a magnetic open circuit. 20 is track direction drive coil 1
It is preferable to install a magnetic member located outside the track direction drive coil 11 and fixed to the slider 3 so as to increase the magnetic flux density acting on the track direction drive coil 11.

The angle 'l# lens support unit 5 is 1 in the optical axis direction,
is supported at the center of a cross-shaped leaf spring 21. Each support leg 21a of this cross-shaped leaf spring 21 is made of a narrow body inclined by approximately 45 inches with respect to the track direction T.
Its outer end is fixed to the slider 3. In this way, the shape of the leaf spring 21 is made into a single character shape, and each support leg 21a
is tilted at 45° with respect to the track direction T (this is done so that the pair of upper and lower leaf springs 21 can displace the objective lens 4 in the focus direction F and the track direction T. Also, 1) A cross-shaped leaf spring 21 supporting the objective lens 4
The central portion of can be bent and displaced in either the focus direction F or the track direction. As shown in FIG. 6, the objective lens support unit 5 is divided into upper and lower parts.
The center portions of the upper and lower leaf springs 21 are fixed to b. The upper unit 5a is fitted in the inner unit 5b so as to be movable in the optical axis direction, and the objective lens 4 is supported by the upper unit 5a.

Therefore, in this device having the above configuration, when a current is applied to the focus direction drive coil 10, the objective lens 4 is driven in the focus direction based on the same operating principle as the conventional device. Also, when current is applied to the track direction drive coil 11, the track direction drive coil 11
2. The vertical portion 11v of the evening direction drive coil ll is connected to the permanent magnet 1.
4 and the leg portion 15a of the yoke 15 or the magnetic material 2o
Since the relationship is perpendicular to the magnetic flux leading to T, the track direction drive coil 11 receives a force in the track direction T. That is, the objective lens 4 is driven in the track direction T.

FIGS. 8 and 9 show another embodiment of the present invention. This embodiment is an embodiment in which the objective lens 4 is driven in the focus direction F by only one of the pair of magnetic circuits 12, and the permanent magnet of the magnetic circuit 12 on the left side of FIG. In addition to the magnet 25, a pair of track direction drive coils 11 are provided on both sides of the focus direction drive coil 10, biased toward the large permanent magnet 25 side.
are fixed respectively. Further, a magnetic member 20 for reinforcing the magnetic flux is also arranged biased in the same direction as the track direction drive coil 11.

- The manner in which the support unit 5 of the χ-1 object lens 4 supports the slider 3 is similar to that of the conventional device, and the slider 3
The other ends of a pair of leaf springs 26, which are deformable in the track direction T, and which have one end fixed to the intermediate member 27, are fixed to a relay member 27, and one end thereof is fixed to the intermediate member 27. A pair of leaf springs 28 that can be deformed in the focus direction F are fixed to the objective lens support unit 5. ''--The enlarged permanent magnet 25 is provided in the magnetic circuit 12 on the far side with respect to the relay member 27, and similarly, the track direction drive coil 11 is also biased toward the far side with respect to the relay member 27.

According to this embodiment, by supplying a current to the track direction driving coil 11, the objective lens 4 can be driven in the track direction ゛l゛ based on the operating principle of the first embodiment and the circuit. Since the direction drive coil 11 is provided in a biased manner, it is possible to downsize the truck 2 direction drive coil 11. Therefore, it is possible to obtain an objective lens driving device in which the weight of the movable part is further reduced 11). Note that driving in the focus direction F can be performed in the same manner as described above by passing a current through the focus direction drive coil IO.

As shown in E-E, the present invention does not place the track direction drive coil of the objective lens drive device in the gap of the yoke of the magnetic circuit, but rather places it near the magnetic circuit at a position where the magnetic flux of the magnetic circuit is cut off. Since the track-direction drive coil is located at the center, there is no need to bend the track-direction drive coil, and its shape can be simplified, increasing productivity and reducing the possibility of wire breakage. Furthermore, since the number of track direction drive coils can be reduced from four groups to two groups, the work of manufacturing the coils and fixing them to the focus direction drive coil becomes easier, and further contributes to weight reduction.

Therefore, drive sensitivity can be increased.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing the relationship between the slider and optical recording disk of an optical information recording/reproducing device, Fig. 2 is a side view of a conventional objective lens drive device j1 mounted on the slider, and Fig. 3 is the same plane. Figures 4 and 4 are perspective views of the focus direction drive coil and track direction drive coil, and Figures 5 to 7 show embodiments of the objective lens drive device of the present invention! ,
FIG. 5 is a side view of II, FIG. 6 is an exploded side view, FIG. 7 is a perspective view of a focus direction drive coil and a track direction drive coil, and FIGS. Fig. 8 is a plan view and Fig. 9 is a four-dimensional view.
FIG. 3 is a perspective view of a scrap direction drive coil and a track direction drive coil. L... Optical recording disk, 3... Slider, 4...
...Objective lens, lO...Focus direction drive coil, 11...Track direction drive coil, 12...Magnetic circuit, 13...Gap, 14.25...Permanent magnet, 15...Yoke , 20... Magnetic member. Patent Applicant Asahi Optical Co., Ltd. Agent Kunio Miura Procedural Amendment (Apparently March 2811, 1981) Commissioner of the Japan Patent Office Kazuo Wakasugi Patent Application No. 229297 1982 2 Title of the invention Optical information Relationship between the objective lens drive device 3 of the recording and reproducing device and the person making the correction Patent applicant address 2-36-9 Maeno-cho, Itabashi-ku, Tokyo Name (0
52) Asahi Optical Industry Co., Ltd. Representative Toru Matsumoto 4, Agent Address: 102 6 Contents of amendment (1) Specification, page 1O, lines 3 and 4, 7'4 Te, F
The words "plate spring" in the 19th line, the 12th line, and the 17th line are replaced with "elastic member", respectively. (2) In the same book, same page, tit, line 5 to line 6, the description ``It consists of a narrow inclined board'' is changed to ``Inclination 1.)''.
%, the whole is composed of elastic materials such as rubber materials and leaf springs).'' (:3) In the same book, page 11, lines 15 and 16, the description “focus direction F” is replaced with “track direction T” +Ii
+l2. (4) "Figure ri7" in line 17 of page 1 of the same book is corrected to "Figure 8." (5) "Focus direction" on page 14, line 11 of the same book is corrected to "focus direction."that's all

Claims (1)

[Claims] (1) Move an objective lens that irradiates laser light onto the optical recording disk to a slider movable in the radial direction of the optical recording disk in the focus direction and in the track direction of the disk! A magnetic circuit consisting of a magnet and a U-shaped yoke is fixed to the slider, and the objective lens is moved in the focusing direction in cooperation with this magnetic circuit to the objective lens support member. In an objective lens drive device of an optical information recording/reproducing device in which a focus direction drive coil driven in a track direction and a track direction drive coil are fixed, the track direction drive coil is located outside the gap of the yoke of the magnetic circuit, and An objective lens drive device for an optical information recording/reproducing device, characterized in that the objective lens drive device is disposed at a position that cuts the magnetic flux of a magnetic circuit. (2. In claim 1, an objective lens of an optical information recording/reproducing device is provided with a pair of magnetic circuits, and a track direction drive coil is provided biased toward one of the pair of magnetic circuits. Drive device?1゜(3) In claim 1 or 2, a magnetic member is provided near the magnetic circuit on the yoke to increase the magnetic flux density in a portion where the track direction driving coil is provided. Optical information recording and reproducing bag; ν1 objective lens drive device.