JPS6325839A - Optical pickup - Google Patents

Abstract

PURPOSE:To reduce the number of parts and to reduce the cost and to keep high reliability by constituting an attaching part, a lens supporting part, and a connecting means with a synthetic resin and forming these parts integrally. CONSTITUTION:An optical pickup which is used in a compact disk player or the like and optically reads and writes a signal is provided with a lens operating member 3 having an attaching part 4 for attachment to a base body 1, a lens supporting part which supports a lens 5, and connecting means 7a and 7b which connect the lens supporting part 6 to the attaching part 5 so that the lens supporting part 6 can be moved while being kept parallel with the recording face of a recording medium to perform at least the focusing operation. The attaching part 4, the lens supporting part 6, and connecting means 7a and 7b consist of a synthetic resin and are formed integrally. Thus, the number of parts is reduced as much as possible, and an unfavorable influence due to the assembling error of the lens operating member is eliminated to obtain the optical pickup with high precision.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical pickup for optically reading and/or writing signals.

[Summary of the invention]

The present invention relates to an optical pink-up used in a compact disc player, etc., for performing at least one of optically reading and writing signals, which includes: a mounting section for attaching to a base body, and a mounting section for supporting a lens. and a connecting means connecting the lens support part to the mounting part so as to enable at least focusing operation, are both made of synthetic resin, and these mounting parts are connected to the lens support part. By integrally molding the connecting means and the connecting means with synthetic resin, it is possible to provide a high-precision optical pickup with a small number of parts and low cost.

[Conventional technology]

Optical pickups are used in compact disc players, optical file systems, laser vision disc players, optical ROM discs, optical RAM discs, and the like. In this optical pickup, the mechanism for supporting the lens frame of the objective lens to perform a focusing operation is a mechanism that allows the lens frame to perform a focusing operation on a bearing holding member for attaching the lens frame to a support shaft provided on a substrate. Most current devices use slide bearings, springs, or cantilever beams to connect them.

[Problem that the invention seeks to solve]

However, each of the above-mentioned focus operation support mechanisms has advantages and disadvantages.

That is, a device using a sliding bearing can have a small driving force, but on the other hand, play inevitably exists between the support shaft and the bearing, and this deteriorates the minute displacement characteristics of the optical pickup. On the other hand, support mechanisms using springs or cantilevers do not cause the above-mentioned backlash, but on the other hand, inherent resonance due to their rigidity occurs at high frequencies.
This puts a limit on the characteristics of the pickup. Also, regarding its static characteristics, it requires a large driving force because it is a mechanism for elastically displacing the connecting member against its own rigidity.

In addition, in any of the above-mentioned support mechanisms, the lens frame of the objective lens, a bearing holding member for attaching the lens frame to a support shaft provided on the substrate, and the lens frame being connected to the bearing holding member for focusing operation. sliding bearing,
Several parts are required, such as springs, cantilever beams, and other connecting means. Therefore, the cost is high, and since it is necessary to assemble these several parts in a predetermined positional relationship, the accuracy is likely to decrease.

[Means for solving problems]

The present invention was invented in view of the above-mentioned problems, and includes a mounting section for attaching to a base body, a lens support section for supporting a lens, and a lens support section for supporting a recording medium. a lens actuating member each having a connecting means connecting the lens supporting portion to the mounting portion so as to move while maintaining a state parallel to the recording surface and perform at least a focusing operation; The mounting part, the lens support part, and the connection means are all made of synthetic resin, and the mounting part, the lens support part, and the connection means are integrally molded with each other from synthetic resin. This relates to optical pickup.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

First, the first embodiment will be explained with reference to FIGS. 1 to 3.
A support shaft 2 is fixed near one end of a substantially rectangular substrate 1 constituting the base of the optical pink amplifier so as to extend perpendicularly to the substrate 1. And this support shaft 2
In this case, the lens actuating member 3 is mounted such that the part 4 is rotatably mounted as will be explained in detail later.

This lens actuating member 3 corresponds to a conventional bearing holding member and is formed into a substantially cylindrical shape, and has a mounting portion 4 which is formed into a substantially cylindrical shape to form a lens frame and has an objective lens 5 attached thereto. The lens support portion 6 is provided with a lens support portion 6, and a pair of plate-like connecting portions 7a and 7b connecting the attachment portion 4 and the lens support portion 6. The cylindrical mounting portion 4, the cylindrical lens support portion 6, and the pair of plate-like connecting portions 7a and 7b are all made of synthetic resin. In order to attach these parts, the part 4, the lens support part 6, and the pair of plate-like connecting parts 7a and 7b are integrally molded with each other by injection molding using synthetic resin. Therefore, the actuating member 3
is constructed as a single injection molded part. The above-mentioned synthetic resin is preferably one that can withstand fatigue due to repeated loads and has elasticity and rigidity comparable to those of ordinary temporary springs; for example, nylon 66 may be used. Furthermore, the method for molding the lens actuating member 3 does not necessarily have to be injection molding, and for example, casting molding may be used.

The pair of plate-like connecting portions 7a and 7b are arranged vertically parallel to each other and each extends substantially horizontally.

Each of the plate-like connecting parts 7a, 7b is attached to a pair of end-side rigid body parts 11a, llb which are connected to the mounting part 4 and the lens support part 6, respectively, and which are constructed with a thick wall, and plate-like connecting parts 7a, 7.
A central rigid body part 12 arranged approximately at the center of b and configured to have a thick wall, and a pair of thin hinge parts 1 formed between the pair of end side rigid body parts 11a, llb and the central rigid body part 12, respectively.
It consists of 3a and 13b. These thin hinge portions 13a, 13b are formed to be narrow in the length direction of the plate-like connecting portions 7a, 7b, and are approximately the same width as the pair of end side rigid body portions 11a, llb and the central rigid body portion 12. It has a length of Note that the thin hinge portions 13a and 13b are narrow but have a certain width, so that stress concentration is unlikely to occur in these portions. The thickness of the thin hinge parts 13a and 13b is the rigid part 11a and llb.
, 12, the thickness is, for example, about 173 to 175. Moreover, the central rigid body part 12 has an inner surface that is substantially flush with the thin hinge parts 13a and 13b, and an outer surface of the central rigid body part 12 that protrudes in a substantially trapezoidal shape with respect to the thin hinge parts 13a and 13b. and - a pair of end-side rigid body parts 11a,
llb has thin hinge portions 13a, 13 on its outer surface.
b, and its inner surface is almost flush with the thin hinge part 1.
3a, 13b, and these hinge parts 13
13b is a sloped surface. Therefore, the joints between the thin hinge parts 13a, 13b and the rigid body parts 11a, 11b112 are designed so that cracks do not easily occur even if the thin hinge parts 13a, 13b are repeatedly bent with respect to these rigid body parts 12. Furthermore, this.

The thin hinge parts 13a and 13b can be formed into the final shape at the same time as injection molding of the lens actuating member 3, but they can be formed thickly in advance and then processed by cutting or the like to the required thickness. Good too.

As clearly shown in FIG. 1, at the other end of the substrate I, a coil bobbin 16 made of a magnetic material and formed in a substantially rectangular plate shape extends approximately perpendicularly to the substrate 1. Fixed.

This coil bobbin 16 has a horizontally long notch 15 formed at the center of its lower end. Further, a tracking operation drive coil 17 is wound around the coil bobbin 16 between its upper end surface and the upper edge surface of the notch 15 . Further, a focus operation drive coil 18 is wound around the coil bobbin 16 between its left and right end surfaces. Further, a light-transmitting opening 19 is formed in the substrate 1 so as to face the lens support portion 5 .

On the other hand, on the side surface of the lens support section 5, a magnet mounting section 20 having a flat surface 20a at a position facing the coil bobbin 16 is integrally molded with the lens support section 6 by injection molding as described above. A rectangular parallelepiped permanent magnet 21 having approximately the same size as the flat surface 20a is fixed by adhesive or the like. Therefore, the permanent magnet 21 faces the coil bobbin 16, and thus the pair of drive coils 17, 18, respectively.

In the optical pickup constructed as described above, the tracking operation drive coil 17 and the focus operation drive coil 18 are wound around the coil bobbin 16 so that the axes of the coils are orthogonal to each other. The tracking operation drive coil 17 is wound so that the winding runs in the vertical direction on the surface of the coil bobbin 16 facing the magnet 21, and on the other hand, the focus operation drive coil 1
8 is wound so that the winding runs in the left-right direction on the opposing surface of the coil bobbin 16.

Therefore, when a current is applied to the tracking drive coil 17, a force in the left and right direction is applied to the magnet 21 facing the coil 17 in accordance with the direction of the current.

This force causes the lens actuating member 3, the magnet 21, and the objective lens 5 to rotate in the left-right direction about the support shaft 2, thereby performing a tracking operation.

In this configuration, a magnetic attraction force always acts between the coil bobbin 16 made of a magnetic material and the magnet 21, and this force also acts between the mounting portion 4 and the support shaft 2. This magnetic attraction force is determined by the size of the magnet 21, the strength of magnetization,
Although it varies depending on the size of the air gap between the magnet 21 and the coil bobbin 16, it is usually several hundred grams.

For this reason, when the mounting part 4 is attached to the support shaft 2 using a sliding bearing as in the past, sliding friction occurs in this part, resulting in significant nonlinearity in the static and dynamic characteristics of the pickup. There is a fear.

Therefore, in this embodiment, as shown in FIG. 1, the mounting portion 4 is attached to the support shaft 2 by a pair of upper and lower ball bearings 31a, 31b. That is, each ball bearing 31a, 31b consists of an inner race, an outer race, and a plurality of balls arranged between them. In addition, the inner races of each ball bearing 31a, 31b are fixed to the outer peripheral surface of the support shaft 2, and the inner race of each ball bearing 31a, 31b is fixed to the outer peripheral surface of the support shaft 2, and the mounting part 4 is removed.
is fixed to the inner circumferential surface of the shaft hole 32. The mounting portion 4 is rotatably supported on the support shaft 2 by rolling contact of the balls arranged between the inner race and the outer race.

Note that 33 is a bearing retainer fitted to the support shaft 2, which prevents dirt from entering the inside of the bearings 31a and 31b, and which is attached to restrict movement of the portion 4 in the thrust direction. Further, 34 and 35 are spacers, which are similarly attached to restrict movement of the portion 4 in the thrust direction.

On the other hand, when a current is applied to the drive coil 18 for focus operation, a vertical force is applied to the magnet 21 facing the coil 18 in accordance with the direction of the current. 6 and the objective lens 5 are rotated in the vertical direction with respect to the attachment part 4, and a focusing operation is performed for this purpose.In this case, the lens operating member 6 has a pair of plate-like connecting parts 7a and 7b, respectively. A pair of thin hinge portions 13a and 13b are provided on each of these plate-like connecting portions 7a and 7b.Therefore, one thin hinge portion 13a and the other thin hinge portion 1 are provided.
3b, these connecting parts 7a, 7b are bent at each thin hinge part 13a, 13b so that the rotation direction of each plate-like connecting part 7a, 7b is exactly opposite. , 7b are bent and deformed into a crank shape. As a result, the lens support portion 6 moves substantially in the vertical direction while maintaining a state parallel to the recording surface of the recording medium without changing its direction with respect to the recording surface of the recording medium, as shown by the chain line in FIG.

Next, a second embodiment of the present invention will be described with reference to FIG. Note that in this second embodiment, the pair of plate-like connecting portions 7a and 7b in the previously described first embodiment are replaced with four rod-like connecting portions 41a,
41b, except that it has been changed to 41C141d,
This embodiment has substantially the same configuration as the first embodiment described above. Therefore, the same parts as in the first embodiment are given the same reference numerals, and the explanation thereof will be omitted.

The lens operating member 3 shown in FIG. 4 has four rod-shaped connecting portions 41'a to 41d extending substantially parallel to each other. These rod-shaped connecting parts 412 to 41d are integrally molded with the cylindrical attachment part 4 and the cylindrical lens support part 6 by injection molding using synthetic resin.

Therefore, during focus operation, each rod-shaped connecting portion 41a to 4
1d curves in an arc shape in the vertical direction in substantially the same way, the lens support portion 6 rotates substantially in the vertical direction while maintaining its parallel state. Further, during the tracking operation, the lens actuating member 3 rotates in the left-right direction about the support shaft 2 as in the first embodiment described above. Note that if the rigidity of the rod-shaped connecting portions 41a to 41d is kept low, it is possible to bend each of the rod-shaped connecting portions 41a to 41d in an arc shape in the left-right direction during the tracking operation, as in the case of the focusing operation described above. can. Furthermore, the installation is part 4.
If it is unrotatably fixed to the support shaft 2 which has approximately the same diameter as the shaft hole 32, the lens support part 6 can be connected to the rod-shaped connecting parts 413 to 41d in exactly the same way as in the case of focusing operation.
It is possible to rotate and move left and right by the curvature of.

In the first and second embodiments described above, the permanent magnet 21 was arranged on the side of the lens actuating member 3, and the drive coils 17 and 18 were arranged on the side of the substrate 1, but these were arranged oppositely. Alternatively, various other driving methods may also be used. Although the lens support part 5 is rotated with respect to the substrate 1 during the tracking operation, the lens operating member 3 is attached to the base Fi, 1 so that it can reciprocate in a straight line, so that the lens support part 5 can be rotated in a straight line during the tracking operation. It may be moved in a specific manner.

〔Effect of the invention〕

Since the present invention has the above-described configuration, the number of parts of the optical pickup can be reduced as much as possible.

Further, the cost of the optical pick amplifier can be significantly reduced, and since there is no adverse effect due to assembly errors of lens operating members unlike in the past, it is possible to provide a highly accurate one, which is therefore highly practical.

[Brief explanation of drawings]

The drawings show an embodiment of the optical pickup according to the present invention, in which FIG. 1 is a perspective view of the entire optical pickup in the first embodiment, and FIG. 2 is a plan view of the lens operating member shown in FIG. 1. , FIG. 3 is a side view of the same as above, and FIG. 4 is a perspective view of the entire optical pickup in the second embodiment. In addition, in the symbols used in the drawings, l・----
−−・−・−−1−−−・・・・−・Group vi (substrate)
3・−１−−−・−・−１−−−−−−−・−・・
Lens operating member 4−・−・・−−−～−−−−−−・−
・・Mounting is done in part 5-・−・−・・−・−・・−−−−11−1 Objective lens 6−・−・−・−・・・・・−・・
-・-Lens support parts 7a, 7b・-m------・-・・
- Plate-like connecting portions (connecting means) 13 a , 13 b =
−−−−−− Thin hinge part 21・・−・−−−−−・
---- Permanent magnets 41a, 41b ・---
---It is a rod-shaped connecting portion (connecting means).

Claims (1)

[Scope of Claims] A mounting portion for attaching to the base body, a lens support portion for supporting the lens, and a lens support portion that moves while maintaining a state parallel to the recording surface of the recording medium to at least focus. and a coupling means operatively coupling the lens support to the mounting part, the mounting part, the lens support, and the coupling means all being made of synthetic resin. What is claimed is: 1. An optical pickup comprising: a mounting portion, a lens support portion, and a connecting means, which are integrally molded with each other from synthetic resin.