JPH0754587B2 - Optical head - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an optical head, more specifically, an optical head, in which a head main body formed by a mold or a slidable fitting into the head main body. The present invention relates to a sliding member.

[Prior Art] In recent years, the industry related to information such as computers has been remarkably advanced, and the amount of information handled has been dramatically expanded. Therefore, instead of the conventional magnetic head, an optical head that uses light such as laser light is used to optically record information on a disk-shaped recording medium or the like at high density, or to reproduce at high speed. There is a situation where an optical recording / reproducing device that can be used is attracting attention.

A conventional example of the light source portion of the optical head is shown in FIGS. 7 and 8.

That is, the base side of the laser diode frame 1 in which the through hole 1a passing through the central axis of the cylinder is formed into an appropriate shape suitable for mounting, and the stepped concave portion 1b fitted to the mounting base 2a of the laser diode 2 is formed. It is formed at the end of the through hole 1a so that the laser diode 2 can be fixed. The collimator holding frame 4 to which the collimator lens 3 is fixed is slidably fitted in the through hole 1a. Then, the collimator lens holding frame 4 is moved and adjusted in the optical axis direction Z, and the light provided from the laser diode 2 is passed through the collimator lens 3 to form a parallel light flux. 5, the collimator lens holding frame 4 was fixed. The laser diode frame 1 in the above-mentioned conventional example is made of, for example, aluminum with high precision by a die casting method, or the collimator lens holding frame 4 is finished with high precision by cutting or the like.

On the other hand, it is desirable to reduce the weight of the optical head in order to move quickly, and when using a plastic member suitable for weight reduction and mass production, the same component can be easily mass produced by using a mold, In order to release the mold from the mold, a draft angle is required, and generally a minimum draft angle of 0.02 is required.

[Problems to be Solved by the Invention] Due to this draft, for example, the collimator lens holding frame 4 having the collimator lens 3 requiring sliding adjustment is attached to the laser diode frame 1 having the laser diode 2 attached thereto. When manufactured by the conventional method, the cylindrical portion is tapered as shown in FIG. 9, so this tapered portion hits a corner of the laser diode frame 1 and is forcibly fixed in a state where sliding adjustment cannot be performed. There was a need.

The present invention has been made in view of the above points, and an object of the present invention is to provide an optical head that can be reduced in weight and mass-produced.

[Means and Actions for Solving Problems] In the present invention, in the optical head for optically recording or reproducing by irradiating a recording medium with a light beam, the head main body is molded and processed by a mold. , A portion that maintains a constant distance from the central axis from the end portion to the deep portion on the sliding surface of the fitting hole that is formed in the head main body and in which the sliding member is attached, and from the end portion to the portion other than this portion It is characterized in that there are provided a plurality of portions each forming a draft when the head body is detached from the mold over a deep portion, and sliding with respect to the fitting hole of the head body. A portion in which a freely-fitting sliding member is formed by a mold, and the sliding surface of the sliding member with respect to the head body maintains a constant distance from the central axis from the end to the deep portion. And other than this part Portion and a respective plurality of locations to form a draft angle when leaving the sliding member from the mold over the section to deep, characterized in that as provided.

EXAMPLES The present invention will be specifically described below with reference to the drawings.

1 to 3 relate to a first embodiment of the present invention.
7A shows the shape of the opening of the optical head main body, FIG. 8B is a sectional view taken along the line AA ′ in FIG. 7A, and FIG. 7C is B- in the same figure. FIG. 2 shows a sectional view of the optical head, and FIG. 3 shows a mounting portion of the polarization beam splitter.

In the optical head 11 of the first embodiment shown in FIG. 2, the optical head body 12 is manufactured by using a plastic member. The (optical head) main body 12 is manufactured by using, for example, molds 13, 14, 15 which are separated in three directions as shown by a chain double-dashed line. (The mold part on the outer peripheral side is omitted.) It is formed by the mold 13 in the main body 12 hollowed out in a substantially T-shape by the molds 13, 14 and 15 and has a step shape at the back of the opening 16. A grating 17 is housed in a ring-shaped grating frame 18 in the shaded portion, and is biased by a coil spring 19 in the inner direction along the central axis of the opening 16. On the end side of the opening 16, a recess having a step-like diameter is formed, and the mounting base of the laser diode 21 is fitted into this recess and fixed by a fixing plate 22 such as a leaf spring.

The light beam of the laser diode 21 is a grating 17
Thus, the main beam of 0th order and the sub beam of ± 1st order diffracted light used for tracking control are separated. A lateral hole 23 is formed on the side periphery of the grating body 18 so that the grating frame 18 can be rotated and adjusted, and the grating 17 can be rotated to adjust the direction of separation of the sub-beams.

Behind the grating 17 is a polarization beam splitter.
24 is fixed by attaching one fixing surface A to a flat inner surface of the main body. Then, the collimator lens 26 is fixed to the stepwise expanded portion of the opening 25 formed by using the mold 14 so that the central axis thereof coincides with the opening 16 on the laser diode 21 side, The collimator lens 26 forms a parallel light beam, travels to the objective lens side of an actuator (not shown) through the quarter-wave plate, and is condensed by the objective lens so that the recording medium can be irradiated in spots. is there.

The return light from the recording medium has a polarization direction in the 1/4 wavelength plate in a direction orthogonal to the forward path, is reflected by the polarization beam splitter 24, and the central axis of the opening 27 in the direction orthogonal to the both openings 16 and 25. Concave lens fixed along the lens frame 28
29, Cylindrical lens 31 through 4 split photodetector
The light is received by 32.

The lens holding frame 28 to which the concave lens 29 is fixed is fixed to the adjustment holding frame 33 having an outer diameter slidable in the opening 27.
The cylindrical lens 31 has a flat surface-shaped peripheral edge fixed to the ring-shaped end surface of the lens holding frame 28 by sticking or the like.

The adjustment holding frame 33 is made of a metal member and has a high processing accuracy so that the outer circumference has a predetermined outer diameter.

The lens holding frame 28 fixed to the adjustment holding frame 33 may be made of a metal member or a plastic member.

The concave lens 29 and the cylindrical lens 31 are for performing focus control by the astigmatism method, and are performed by operating output of a photodetector element that is divided into two in a direction orthogonal to the two-division side that performs tracking control by the sub-beam. On the other hand, this added output is used as a reproduction signal. The four-divided photodetector 32 is fixed to the end face of the opening 27 of the main body 12 via a detector mounting plate 34. By the way, the openings 16, 25, formed by the respective molds 13, 14, 15,
The cut surface passing through the central axis of 27 has a tapered inner peripheral surface for releasing. (Note that the dies 13, 14, 15 indicate the portions forming the (inner) opening of the main body 12, and the outer peripheral surface of the main body 12 is actually a tapered surface.) Therefore, in FIG. A thin line and a solid line show the situation. In the first embodiment described above, the cylindrical lens 31 needs to be movable along the optical axis direction for adjustment, and the adjustment holding frame 33 needs to be slidable in order to perform correct focusing or tracking. is there.

In the first embodiment, the adjustment holding frame 33 is slidable by setting the opening 27 portion as shown in FIG.

That is, as shown in FIG. 1 (a), the opening 27 has, for example, an inner peripheral portion in the vertical direction passing through the central axis and an inner peripheral portion in the left-right direction from the end portion of the opening 27 to the deep portion from the central axis of the opening 27. The constant inner radius portions 27A, 27A, 27A, 27A having the substantially constant radii R, R are set, and (Fig. 1 (b) is a sectional view taken along the line AA 'in Fig. 1 (a). On the other hand, as shown in FIG. 1 (c), on the other hand, the taper surface portion (slope surface portion) is formed such that the diameter (width) gradually decreases from the end of the opening 27 to the deep part, as shown in FIG. 1 (c). It's set to 27C.

Most of the openings 27 except for a part thereof are tapered surface parts 27.
Since it is set to C, the required mold release can be realized. Further, since the opening 27 has a substantially constant inner radius R (that is, a minimum gradient) from the central axis at a plurality of locations (4 locations) on the inner peripheral surface, the radius is adjusted to be the outer diameter. The holding frame 33 can slide, and when this slides, the adjusting holding frame 33 can hold the adjustment holding frame 33 in a state in which its central axis almost always coincides with the central axis of the opening 27. Incidentally, as shown in FIG. 2, an opening 27 is formed on the outer periphery of the main body 12.
A horizontal hole is formed for the adjustment holding frame 33, which is fitted inwardly, to move the adjustment holding frame 33 in the optical axis direction by pressing the side wall of the recess, and to be suitable for the focus control cylindrical lens 31. It can be adjusted to any position. (After adjustment, it can be fixed by screws (not shown) in the lateral direction.) Incidentally, a constant inner radius portion and a tapered surface portion are similarly formed for the openings 16 and 25 other than the opening 27. Has been done. Therefore, the laser diode 21, the grating frame 18, the collimator lens 26, etc. can be fixed without rattling.

On the side of the plane B orthogonal to the fixed surface A of the polarization beam splitter 24, a deviating gradient is required in the direction of the opening 27. Therefore, the positioning surface of the fixed surface B seen from the side of the opening 27 is as shown in FIG. I am doing it.

That is, there are provided positioning portions 27D, 27D that project in a line along the central axis direction of the opening 27 (the direction perpendicular to the paper surface in FIG. 3), and the other portions are tapered surface portions 27E in the optical axis direction. I am doing it.

In the first embodiment described above, the optical head is a simplified optical head that fixes the collimator lens 26 with almost no adjustment. However, the collimator lens 26 is attached to a metal lens holding frame, and the lens holding frame is adjusted and held. It may be slidable in the optical axis direction like the frame 33. Further, the laser diode 21 can be fixed via a metal frame so that it can slide in the opening 16 of the main body 12.

Further, in the first embodiment described above, the main body 12 on which the metallic adjustment holding frame 33 is slidable is made of a plastic member, but the relationship between the two can be exchanged.

FIGS. 4 and 5 show a metal main body 42 and a plastic adjustment holding frame 43 in the second embodiment of the present invention.

In the second embodiment, the opening 44 corresponding to the opening 27 in the first embodiment is formed with a constant inner radius R with high precision as shown in FIG. On the other hand, the adjustment holding frame 43 slidably fitted in the opening 44 has a constant outer radius portion 43A having an outer diameter substantially equal to the radius R, as shown in FIG.
It is formed at four places, and the remaining portion is a tapered surface portion 43B. In this way, the molds can be separated from each other and can slide.

The inner opening 43C is tapered. When the adjustment holding frame 43 is fitted into the opening 44 of the main body 42, the adjustment holding frame 43 becomes slidable in the opening 44. The operation of the second embodiment is substantially the same as that of the first embodiment.

FIG. 6 shows a third embodiment of the present invention. In the third embodiment, similarly to the first embodiment, the adjustment holding frame 33 is made of metal so that it can slide in the opening 27 of the main body 51.

In the main body 51, the opening 27 in which the four-division photodetector 32 is attached to the end face has the same structure as that of the first embodiment.
Most of the peripheral surface is a tapered surface, and a constant inner radius portion is formed at a plurality of locations.

On the other hand, an opening 53 into which the laser diode frame 52 can be fitted is formed in the main body 51, and the opening 53 has the same structure as the opening 27. The laser diode frame 52 fitted into the opening 53 has a structure in which a metal member is used to form a portion having the constant inner radius portion as the outer radius and can be slid. The openings 27 and 53 having the slidable structure are shown by thick solid lines.

The laser diode 21, the grating 17, the polarization beam splitter 24, the collimator lens 26, etc. are attached to the laser diode frame 52.

In the third embodiment, the concave lens 29 and the cylindrical lens 3 are used.
There is an advantage that the collimator lens 26 side can be further adjusted to an appropriate position with respect to the adjustment holding frame 33 to which 1 is attached.

In the third embodiment, the main body 51 may be made of metal and the adjustment holding frame 33 and the laser diode frame 52 side may be made of plastic. Further, the collimator lens 26 may be movable with respect to the laser diode frame 52. The non-metal member is not limited to the plastic member as long as it can be easily manufactured with a mold.

It is obvious that the present invention can be widely applied to optical heads having different configurations.

[Advantages of the Invention] As described above, according to the optical head of the present invention, mass production is possible, required mold release is possible, and sliding adjustment or rattling is performed without rattling. Can be fixed.

[Brief description of drawings]

1 to 3 relate to a first embodiment of the present invention.
FIG. 6A is a front view showing an opening into which an adjustment holding frame having a cylindrical lens or the like mounted in the optical head body used in the first embodiment is slidably fitted, and FIG. 3A is a sectional view taken along the line AA ', FIG. 3C is a sectional view taken along the line BB' in FIG. 2A, and FIG. FIG. 4 is a front view showing the positioning portion of the polarization beam splitter, FIG. 4 is a front view showing the optical head body in the second embodiment of the present invention, and FIG.
FIG. 5A is a front view showing an adjustment holding frame fitted in the opening of the optical head body of FIG. 4, and FIG. 5B is the same view as FIG.
FIG. 6 is a sectional view showing an optical head in a third embodiment of the present invention, and FIG. 7 is a sectional view showing a collimator lens frame slidably fitted in a laser diode frame in a conventional example, FIG. 8 is a sectional view taken along the line DD ′ of FIG. 7, and FIG. 9 is a sectional view showing a fixing means of a collimator lens frame in another conventional example. 11 …… Optical head, 12 …… Main body 13,14,15 …… Mold 16,25,27 …… Aperture 27A …… Constant inner radius part, 27C …… Tapered surface part 28 …… Lens holding frame, 29… … Concave lens 31 …… Cylindrical lens 33 …… Adjustment holding frame

Claims (2)

[Claims] 1. An optical head for optically recording or reproducing by irradiating a recording medium with a light beam, wherein a head body is molded by a mold, and a sliding member is formed on the head body. On the sliding surface of the fitting hole to which is attached, a portion that keeps a constant distance from the central axis from the end portion to the deep portion, and at a portion other than this portion from the mold to the head body from the end portion to the deep portion. An optical head characterized in that a plurality of portions are formed at each of which a slope is formed at the time of leaving the head. 2. An optical head for irradiating a recording medium with a light beam for optical recording or reproduction, wherein a sliding member slidably fitted in a fitting hole of the head body. Is formed by a mold, and at the sliding surface of the sliding member with the head body, a portion that keeps a constant distance from the central axis from the end portion to the deep portion, and an end portion at a portion other than this portion. An optical head, characterized in that a plurality of portions are formed from a portion to a deep portion to form a draft when the sliding member is detached from the mold, respectively.