JPH0770079B2 - Method for manufacturing suspension of optical pickup device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method of manufacturing a suspension of an optical pickup device used for reproducing information from an optical disc such as a video disc or a compact disc.

[Conventional technology]

Conventionally, as an optical pickup device of this type, a magnet is attached to a holder on which an objective lens is mounted, and the magnet is moved by a current flowing through a coil fixedly provided facing the magnet to move the holder of the objective lens. An optical pickup device called MM type for operating is known.

FIGS. 6 and 7 show the MM type optical pickup device described above, in which 1 is an actuator base, and two suspensions 2 are provided symmetrically to each of the actuator bases.
The holder 4 of the objective lens 3 is movably supported by the cantilever. A magnet 5 is fixed to the holder 4, and a focus coil 7 and a tracking coil 8 are attached to a yoke 6 fixed to the actuator base 1. The magnet 5 includes the focus coil 7 and the tracking coil. 8 is arranged so as to oppose to each other.

Then, a required current is passed through the focus coil 7 and the tracking coil 8 to generate a force between the focus coil 7 and the tracking coil 8, and the holder 4 of the objective lens 3 is moved in the focus direction and the tracking direction.

The suspension 2 used in such an optical pickup device is configured as four elongated rod-shaped supports 2a, and generally a metal wire or an etching spring is used. Then, in order to provide the metal suspension 2 with a predetermined damping characteristic, a damper material (not shown) such as silicon rubber is put on the outside of the rod-shaped support 2a.

However, in the case of the metal suspension 2 described above, beryllium alloy, phosphor bronze, stainless steel, etc., which are the materials, are very expensive, and the damper material must be attached afterwards, resulting in poor productivity and an increase in manufacturing cost. Had the problem of doing. Also, the suspension 2
Since it is composed of a plurality of parts such as the four rod-shaped supports 2a and the damper material covered by the same, there is also a problem in that the performance of the suspension 2 obtained by assembling the above-mentioned respective parts varies. Was.

Therefore, instead of the metallic suspension 2, the suspension 2 is integrally molded with a synthetic resin material having both a spring property as a suspension and a damping property as a damper, so that inexpensive and stable performance can be obtained. An optical pickup device based on the above is considered.

FIG. 8 shows a rod-shaped support 2a when the suspension 2 is molded with a synthetic resin material. The performance of the suspension 2 required, the material characteristics of the synthetic resin material, and the entire pickup device are limited. From the dimensions, etc., the rod-shaped support 2a has l = 10 to 15 mm, b = h =
It is thought that the size will be about 0.3 to 0.6 mm. In order to mold the suspension 2 having such a rod-shaped support 2a with a synthetic resin material, it is considered to use a so-called injection molding technique.

[Problems to be Solved by the Invention]

However, in the conventional injection molding technique, a so-called ejector pin or ejector block is abutted against the molded product when the molded product is ejected from the mold, so that the suspension having the extremely thin rod-shaped support 2a described above is used. It was very difficult to eject 2 from the mold.

That is, as shown in FIG. 9, when the rectangular ejector block 9 is pressed against the rod-shaped support body 2a of the suspension 2 and released from the mold, a recess is formed in the portion where the block 9 hits, as shown in FIG. There is a problem that bending deformation occurs, the dimensional accuracy of the rod-shaped support 2a cannot be maintained, and as a result, the suspension 2 having a predetermined performance cannot be obtained.

The present invention has been made in view of the above points, and when manufacturing a suspension having an elongated rod-shaped support in a synthetic resin in an optical pickup device, to obtain a suspension having sufficient dimensional accuracy and stable performance. It is an object of the present invention to provide a method of manufacturing a suspension of an optical pickup device capable of performing the above.

[Means for Solving the Problems]

In order to achieve the above object, a method of manufacturing a suspension of an optical pickup device according to the present invention includes a base part attached to a fixed side such as an actuator base at a parting part by joining a fixed type and a movable type, and the base part. A suspension portion having two rod-shaped supports extending from the suspension portion, and a mounting portion formed at the tip of the suspension portion for mounting a movable side such as a holder, and forming a suspension cavity. After the cured synthetic resin was injected and after curing, the movable die was separated from the fixed die, ejector pins were abutted on the base portion and the attachment portion, and high pressure air was blown to the suspension portion to form the molded product. The suspension is discharged from the movable type.

Further, the air ejection port for blowing the high-pressure air to the suspension portion is a long hole having a length of at least half or more of the entire length of the rod-shaped support opened along the rod-shaped support, and the hole of the long hole is formed. The width of the hole is so narrow that the synthetic resin injected into the cavity does not flow out of the jet port due to its viscosity.

[Work]

According to the present invention, when the movable die is separated from the fixed die, the ejector pin is abutted against the base portion which is attached to the fixed side such as the actuator base and the attachment portion which is attached to the movable side such as the holder, and the ejector pin is extended from the base portion to form two pieces. High-pressure air was blown to the suspension part having a rod-shaped support so that the molded suspension was discharged from the movable mold, so that there was no deformation and the like, and a component part of the suspension having sufficient dimensional accuracy and stable characteristics. Can be manufactured, and there is no need to manage the dimensional accuracy of each component as in the conventional case.

Further, the air ejection port for blowing high-pressure air to the suspension portion is a long hole having a length of at least half or more of the entire length of the rod-shaped support opened along the rod-shaped support, and the hole width of the long hole. Since the synthetic resin injected into the cavity has a narrow hole width that does not flow out of the jet port due to its viscosity, the synthetic resin injected into the cavity leaks out of the air jet port. This can be automatically prevented.

〔Example〕

Next, one embodiment of the present invention will be shown in FIGS. 1 to 5, which will be described below.

FIG. 4 is an exploded perspective view of an optical pickup device using a suspension manufactured according to the present invention, and FIGS. 5A and 5B show the suspension. First, the optical pickup device is shown. The suspension will be described.

Reference numeral 11 is an objective lens, 12 is a holder to which the objective lens 11 is attached, and V-shaped grooves 12a are formed on both sides thereof. Reference numeral 13 is a yoke, which is formed by forming U-shaped portions 13a on both sides of the yoke and inserting it into the holder 12
It can also serve as 12 counter weights, and at the same time can increase the strength of the holder 12. Further, a through hole (not shown) is formed at the center of the yoke 13 and the diameter of the through hole is appropriately set so that the aperture diameter can be set.

A magnet 14 is fixed to the inner surface of the U-shaped portion 13a of each yoke 13, and a magnetic gap is formed between the magnet 14 and the outer portion of the U-shaped portion 13a.

Reference numeral 15 is a suspension integrally formed of plastic such as polyester elastomer. As shown in FIG. 5, two base portions 15a are connected by a thin portion 15b to form a mounting base portion 15e to an actuator base 16 which will be described later. Outside each of the base portions 15a, there is a suspension portion 15f having two elongated rod-shaped support members 15c having a rectangular cross section, and a V-shaped holder attachment portion 15d is provided on the outside thereof. . In this suspension 15, as shown in FIG. 4, the thin-walled portion 15b is curved to make the pair of suspension portions 15f parallel to each other, and then the holder mounting portion 15d is attached to the groove 12a of the holder 12.
It is to be attached to.

16 is an actuator base, which has two columns 16a
And a prism 16b are erected, and the base portion 15a of the suspension 15 is attached to this and the suspension 15 is attached to the actuator base 16. As a result, the suspension portion 15f movably supports the holder 12 with respect to the actuator base 16 in a cantilever manner.

Reference numeral 17 is a bobbin molded of a non-magnetic material, around which a focus coil 18 is wound, and a tracking coil 19 is fixed to one surface of the bobbin, and a pin 17a standing on the lower surface of the bobbin 17 is attached to the actuator base. It is inserted into 16 holes 16c. As a result, the focus coil 18 and the tracking coil 19 are attached to the actuator base 16 within the magnetic gap formed between the magnet 14 and the outer side of the U-shaped portion 13a of the yoke 13.

Actuator base 16 assembled in this way
Is inserted into the groove 20a of the skew knob 20 in the circular groove 16d,
By mounting the skew knob 20 on a pickup body (not shown), the skew knob 20 is attached to the pickup body together with a flexible substrate (not shown). The focus coil 18 and the tracking coil 19 are connected to the flexible substrate and led out of the pickup device.

Further, the actuator base 16 is such that the angle with respect to the pickup body can be adjusted by the rotation of the skew knob 20 and the spring 21 interposed between the actuator base 16 and the pickup body.

In this optical pickup device, a required current is passed through the focus coil 18 and the tracking coil 19 to generate a force between the focus coil 18 and the tracking coil 19, and the holder 12 of the objective lens 11 is moved in the focus direction and the tracking direction. . A magnetic gap is formed between the U-shaped portion 13a acting as a yoke and the magnet 14, and the focus coil 18 and the tracking coil 19 are located in this magnetic gap.
Even if the character portion 13a and the magnet 14 are operated, the effective magnetic flux portion does not come off the focus coil 18 and the tracking coil 19 and the sensitivity is not lowered.

The suspension 15 used in the optical pickup device configured as described above is manufactured, for example, as follows.

As shown in FIGS. 1 and 2, the synthetic resin material such as polyester elastomer loaded in the hopper 22 is a ram.
By the reciprocating motion of 23, it is sent into the cylinder 24, where it is heated by the heater 25 and fluidized. Then, the fluidized synthetic resin material enters the mold 27 through the nozzle 26 at the end of the cylinder 24, passes through the sprue 28 and the gate 29 formed on the fixed mold 27a side of the mold 27, and then the fixed mold 27a. And movable 27b
By the joining of the above, it enters into the cavity 31 formed along the parting line 30.

Since the cavity 31 is formed so as to form the suspension 15 having the shape shown in FIG. 5,
The synthetic resin material that has entered the cavity 31 is cooled and hardened therein to form the suspension 15 having the above-described predetermined shape. Since the molded suspension 15 has a predetermined performance, the dimension of the rod-shaped support 15c having a rectangular cross section that constitutes the suspension portion 15f is
It is molded so that l = 10 to 15 mm and b = h = 0.3 to 0.6 mm.

Therefore, in order to take out the molded product of the suspension 15 having the above-mentioned shape from the mold 27, the movable mold 27b is fixed to the fixed mold 27a.
And ejects a plurality of ejector pins 32 provided on the movable die 27b against the base portion 15a and the holder attachment portion 15d of the suspension 15 and outputs high pressure air from the air ejection port 33 formed on the movable die 27b. The molded product is discharged from the movable die 27b by spraying it onto the suspension portion 15f composed of the rod-shaped support 15c.

The air ejection port 33 formed on the movable die 27b is connected to the compressor 35 via the solenoid valve 34 as shown in FIG.
The solenoid valve 34 is opened and closed by the movable type.
This is performed at the same time as the release of 27b and the ejection of the ejector pin 32. Also,
The air ejection port 33 has a width t as shown in FIG.
Is about 0.01 mm and its length L is formed as a gap of about l / 2 to 1 of the length (l) of the rod-shaped support 15c. Further, the air jet port 33 can be used also as a gas vent for discharging the gas in the mold 27 by switching the solenoid valve 34.

Further, the synthetic resin material such as the polyester elastomer is preferably of a type having flow characteristics such that it does not enter the air ejection port 33, and its melt flow index is about 2-20.

Therefore, in this embodiment, the extremely thin rod-shaped support 15
Since high-pressure air is blown to the suspension part 15f made of c to perform mold release, a recess may be formed in the rod-shaped support or bending deformation may occur like the case of mold release by a conventional ejector block. Absent. For this reason,
The dimensional accuracy of the molded rod-shaped support 15c can be sufficiently maintained, and as a result, the suspension 15 having stable performance can be manufactured at one time by integral molding.

The thin-walled portion 15b of the integrally molded suspension 15 described above
It is also possible to cut out the suspension as needed, which provides a suspension with sufficient dimensional accuracy and stable performance.
It is capable of producing 15 components.

〔The invention's effect〕

As described above, the method of manufacturing the suspension of the optical pickup device according to the present invention, when the movable die is separated from the fixed die, the base portion attached to the fixed side such as the actuator base and the attachment portion attaching the movable side such as the holder. Since the ejector pin was abutted and high pressure air was blown to the suspension part extending from the base part and having two rod-shaped supports to eject the molded suspension from the movable mold, sufficient dimensional accuracy and stability were obtained. It is possible to manufacture a suspension component having the above-mentioned performance, and the air ejection port for blowing high-pressure air to the suspension portion has at least a half or more of the entire length of the rod-shaped support opened along the rod-shaped support. A synthetic resin having a long hole having a length of, and the hole width of the long hole is injected into the cavity. There since the narrow pore width of extent without flowing to the outside from the ejection port by its viscosity,
It is possible to automatically prevent the synthetic resin injected into the cavity from leaking out from the air ejection port.

[Brief description of drawings]

FIG. 1 is a schematic view of a mold used in one embodiment of the present invention, FIG. 2 is a schematic configuration diagram of an injection molding machine used in the above embodiment, and FIG. 3 is a view showing details of an air ejection port, FIG. 4 is an exploded perspective view of an optical pickup device using a suspension manufactured according to the present invention, and FIGS. 5 (A) and 5 (B) are a developed side view and a plan view of the suspension, FIGS. 6 and 7. Is a plan view and a cross-sectional view of a conventional optical pickup device, FIG. 8 is a view showing a desirable shape of a rod-shaped support body of a synthetic resin suspension, and FIGS. 9 and 10 are conventional releasing methods and releasing methods thereof. It is a figure which shows the modeled suspension. 2,15 …… Suspension, 2a, 15c …… Bar support, 15a
…… Base, 15d …… Holder mount, 15e …… Mount base, 15
f …… Suspension part, 27 …… Mold, 27a …… Fixed mold,
27b: Movable type, 31: Cavity, 32: Ejector pin, 33: Air jet.

Claims (2)

[Claims] 1. A base part to be mounted on a fixed side such as an actuator base in a parting part by joining a fixed type and a movable type, a suspension part having two rod-shaped supports extending from the base part, and a suspension part of the suspension part. A cavity is formed which is composed of a mounting portion for mounting a movable side such as a holder formed at a tip portion, and a fluidized synthetic resin is injected into the cavity through a gate. An optical pickup device characterized by ejecting a molded suspension from the movable die by abutting ejector pins on the base portion and the attachment portion and blowing high pressure air to the suspension portion when separating from the fixed die. Manufacturing method of the suspension. 2. An air outlet for blowing high-pressure air to the suspension portion is a long hole having a length of at least half or more of the entire length of the rod-shaped support body opened along the rod-shaped support body, and 2. The optical pickup device according to claim 1, wherein the hole width of the long hole is set to a narrow hole width such that the synthetic resin injected into the cavity does not flow out of the ejection port due to its viscosity. Manufacturing method of the suspension.