JPH02220228A - Optical head - Google Patents

Abstract

PURPOSE:To obtain a recording signal of high quality and remove restrictions on head main body materials by fixing a semiconductor laser to a prescribed plate, and attaching this plate to a head main body so that its angle can be adjusted. CONSTITUTION:A semiconductor laser 6 is fixed to an attaching plate 16, which is made of aluminium or the like and has the heat radiation effect, by an attaching screw 17, and this plate 6 is temporarily fixed to a head main body 15 with a coiled spring 20 between them by an adjusting screw 21. At this time, the front end of a projection 18 is inserted into an aperture 19 of the main body 15 to engage an outside peripheral surface 18A with a front end 19A of the aperture 19. For the purpose of correcting the deviation of the center of the intensity of parallel rays due to the variance of the angle of spread of the laser 6, the attaching angle of the plate 16 is changed by loosening or tightening the screw 21 in the proper position to match the center of the intensity of parallel rays, which passes a collimator lens 7, to its optical axis. Since the laser beam passes the center of an objective lens 5 by this constitution, a recording/reproducing signal of high quality is obtained on a disk 1. Restrictions on head main body materials are unnecessary.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical head for recording and/or reproducing information on an information storage medium such as an optical disc or a compact disc (CD).

2. Description of the Related Art A conventional optical disk recording and reproducing apparatus, as shown in FIG. 4, includes a disk motor 2 for rotating a disk 1;
An optical head 3 for recording and reproducing information on the day A1, and a transport unit (for example, a linear motor, etc.) 4 for moving the optical head 3 in the radial direction of the disk 1.
have.

As shown in FIG. 5, the optical head 3 focuses an objective lens 5, a semiconductor laser 6 as a light source, a collimator lens 7, a polarizing prism 8, a quarter-wave plate 9, and an objective lens 5. An actuator 10 of an evaporative coil type, for example, which constitutes a magnetic circuit for driving in the direction and the tracking direction, a prism 11, and a detection lens 12,
It has a focus detector 13, a tracking error signal/reproduction signal detector 14, a head body 15 to which these parts are attached, and the like. Usually, the semiconductor laser 6
is attached directly to the head body 15, and the head body 1
5 is made of a material with high heat dissipation effect in order to dissipate the heat generated by the semiconductor laser 6.

In order to perform recording or playback in the device with the above configuration,
The optical head 3 is driven by a transfer unit 4, performs a rough search for a target address on the disk, and reaches the target address by finely moving the objective lens 5 in the optical head 3 by an actuator 10.

On the other hand, in FIG. 5, a laser beam from a laser 6, which is a light source, is converted into parallel light by a collimator lens 7, and the optical path is changed upward by a polarizing prism 8, and a quarter-wave plate 9
, and is imaged onto the disk 1 by the objective lens 5. At this time, the focusing drive and tracking drive are performed by operating the actuator 10 to slightly move the objective lens 5 in response to signals from the focus detector 13, the tracking error signal, and the reproduction signal detector 14. The reflected light from the disk 1 passes through the objective lens 5 and passes through the quarter-wave plate 9 again, so that the next time it enters the polarizing prism 8, the light is transmitted. A portion of this transmitted light is reflected by the prism 11 and guided to the focus detector 13 via the detection lens 12. The other light passes through the prism 11 and is guided in the far field to a detector 14 that also serves as a tracking error signal and reproduction signal.

Problems to be Solved by the Invention However, with this configuration, there is a problem that the center position of the intensity of the parallel light incident on the objective lens varies, degrading the optical performance, and that the head body is made of a material with high heat dissipation effect. The problem was that it was restricted to

The above problem arises for the following reasons. In other words, although the semiconductor lasers 6 each have variations in the center of their divergence angles (around ±2 degrees), the conventional device has a structure in which the semiconductor lasers 6 are directly fixed to the head body, so it is possible to mount them according to the design values. Even in this case, variations occur in the center of the collimated light intensity after collimation. If the actuator 10 is fixed uniquely at the designed position despite the deviation in the parallel light output position, the optical axis will be shifted, which will be a major factor in performance deterioration. In addition, in order to correct this optical axis misalignment, the position of the actuator 10 is made adjustable, and the actuator 1
It is conceivable to use a jig or the like to align the optical axes when mounting the actuator 10, but this would require readjustment when replacing the actuator 10, which is not efficient.

Furthermore, due to laser life issues, it is necessary to use a material with a high heat dissipation effect (aluminum, etc.) as the material of the head body, so it is not possible to use a resin or the like which is more advantageous in terms of specific gravity.

The present invention has been made in view of the above-mentioned problems, and it is possible to obtain high-quality recording/reproduction signals without variations in the position of parallel light incident on the objective lens, and has a heat dissipation effect as a head body material. An object of the present invention is to provide an optical head that is not limited by materials with high densities.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention has a structure in which a semiconductor laser is fixed to a mounting plate having a heat dissipation effect, and this mounting plate is mounted to the head body so that its angle can be adjusted. It is something.

Here, as a mechanism for attaching the mounting plate to the head body in an adjustable manner, a plurality of coil springs are sandwiched between the mounting plate and the outer surface of the head body, and the mounting plate is attached to the head body with adjustment screws. Furthermore, a protrusion is provided on the head body side surface of the mounting plate, and the protrusion is centered on the central axis of the semiconductor laser attached to the mounting plate and gradually becomes smaller in diameter toward the tip, and the protrusion is formed on the head body. Preferably, it is configured to engage with the opening.

Function: As described above, the mounting plate holding the semiconductor laser can be adjusted in angle with respect to the head body.
By adjusting the mounting angle of this mounting plate with respect to the head body, it is possible to adjust the intensity peak from the semiconductor laser to be at the center of the collimator lens, thereby bringing the optical axis of the parallel light very close to the ideal optical axis. The relative position of the center of the beam intensity of the laser beam before entering the objective lens and the center of the objective lens can be made almost the same. Therefore, the beam profile imaged onto the disk is unbiased, making it possible to obtain high-quality recording and reproduction signals. Furthermore, since the mounting plate has a heat dissipation effect, there is no need for the head body to have a heat dissipation effect, and it is possible to use an inexpensive and lightweight resin as the head body material.

Furthermore, as mentioned above, if the mounting plate is provided with a protrusion, the protrusion is engaged with the opening of the head body, and the mounting plate is attached to the head body using a plurality of coil springs and adjustment screws, it is possible to By tightening or loosening the adjusting screw at the appropriate position, the angle of the mounting plate can be freely changed around the position where the protrusion is secured to the opening, and therefore the position of the light emitting point of the semiconductor laser can hardly change. The angle can be easily adjusted.

Embodiment FIG. 1 is a side view showing a schematic configuration of an optical head according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view showing the vicinity of a semiconductor laser in the embodiment, and FIG. 3 is an exploded perspective view thereof. It is. Note that parts that are the same as or similar to those of the conventional example shown in FIGS. 4 and 5 are designated by the same reference numerals.

In FIG. 1, 1 is an optical disk, 2 is a disk motor for rotating the optical disk, 3 is an optical head for recording and reproducing information on the disk 1, and 4 is for moving the optical head 3 in the radial direction of the disk l. This is a transfer unit (for example, a linear motor, etc.) for moving the object. This optical head 3 includes an objective lens 5, a semiconductor laser 6 as a light source,
A collimator lens 7 that converts the light emitted from the laser 6 into parallel light, a polarizing prism 8, a quarter-wave plate 9, an actuator 10. Prism 11, detection lens 12, focus detector 13, tracking error signal/reproduction signal detector 14, and head body 15 to which these parts are attached.
etc.

In FIGS. 2 and 3, the semiconductor laser 6 is fixed by a mounting screw 17 to a mounting plate 16 made of aluminum or the like and having a heat dissipation effect. The mounting plate 16 has a protrusion 18 centered on the central axis of the semiconductor laser 6 attached to the mounting plate on the surface facing the head body 15, and the protrusion 18 has a protrusion 18 on at least the tip portion of its outer periphery.
It has an outer circumferential surface 18A (a tapered surface in the illustrated embodiment) that gradually becomes smaller in diameter toward the tip. On the other hand, the head body 15
An opening 19 having an inner diameter smaller than the maximum outer diameter but larger than the minimum outer diameter of the outer circumferential surface 18A of the projection 18 is formed in the opening 19, and the tip portion of the projection 18 can be inserted into this opening 19. The center of the aperture 19 is the collimator lens 7.
It is formed so as to coincide with the optical axis X--X of.

Between the mounting plate 16 and the outer surface of the head body 15,
Coil springs are arranged near each of the four corners of the mounting plate, and adjustment screws 21 attach the mounting plate 16 to the head body 15.

Note that it is not necessary to use a material with a high heat dissipation effect for the head body 15, and an inexpensive resin or the like can be used.

Regarding the optical head configured as described above, the mounting and adjusting operations of the semiconductor laser will be described below.

The semiconductor laser 6 is fixed at a predetermined position on the mounting plate 16 with mounting screws 17 . Then, the mounting plate 1
6 is temporarily fixed to the head body 15 using an adjusting screw 21 with a coil spring applied therebetween. At this time, insert the tip of the protrusion 18 into the opening 19 of the head body 15, and
8A is engaged with the tip edge 19A of the opening 19. As a result, the light emitting point 6A of the semiconductor laser 6 is aligned with the collimator lens 7.
It will be located on the optical axis XX. Next, in order to correct the deviation of the center of parallel light intensity due to variations in the divergence angle of the semiconductor laser 6, the adjustment screws 21 at appropriate positions are loosened and tightened. Thereby, the mounting angle of the mounting plate 16 changes, and the angle of the semiconductor laser 6 with respect to the collimator lens optical axis can be changed, and the intensity center of the parallel light after passing through the collimator lens 7 can be made to coincide with the collimator lens optical axis. Can be done.

Here, when adjusting the angle of the mounting plate 16, at least one point on the outer circumferential surface 18A of the protrusion 18 is aligned with the tip edge 19 of the opening 19.
If the position of the light emitting point 6A of the semiconductor laser 6 is kept in the engaged state with #1, the position of the light emitting point 6A of the semiconductor laser 6 will hardly change when the angle of the mounting plate changes, thus allowing accurate adjustment.

With the above adjustment, the intensity center of the laser beam emitted from the semiconductor laser 6 enters the center of the collimator lens 7, and therefore the laser beam, which has been made into a parallel beam by the collimator lens 7, travels approximately on the ideal optical axis of the optical head. As it advances, it passes through the center of the objective lens 5. For this reason,
The beam profile imaged onto the disk 1 by the objective lens 5 is unbiased, and high-quality recording/reproduction signals can be obtained. Note that the adjusted mounting plate 16 is held between the coil spring and the head of the adjustment screw 21, and although it is not strictly fixed to the head body 15, the mounting plate 16 is held between the coil spring and the head of the adjustment screw 21. By appropriately selecting the strength of the addition, it can be fixed so that it does not move, and there is no problem.

In the above embodiment, a tapered surface is used as the tip outer circumferential surface 18A of the protrusion 18 of the mounting plate 16, but this shape is not limited to a taper, but can be any shape as long as it gradually becomes smaller in diameter toward the tip. I don't care.

For example, the outer circumferential surface of the tip of the protrusion may be a spherical surface centered on the light emitting point 6A of the semiconductor laser 6. In this case, the spherical surface is pressed against the entire circumference of the tip edge 19A of the opening 19, and the mounting plate is Adjustment can be made, and since the position of the light emitting point 6A is not displaced at that time, more accurate adjustment is possible.

Effects of the Invention As is clear from the above explanation, the present invention has a semiconductor laser fixed to a mounting plate that has a heat dissipation effect, and this mounting plate is attached to the head body so that its angle can be adjusted. By adjusting the mounting angle of the mounting plate relative to the head body, it is possible to adjust the intensity peak of the light from the semiconductor laser to be at the center of the collimator lens, thereby making the optical axis of the parallel light extremely close to the ideal optical axis. state, the relative position of the center of the laser beam intensity and the center of the objective lens can be almost matched, and an even beam profile can be imaged on the disk, making it possible to obtain high-quality recording and reproducing signals. It has this effect.

Furthermore, since the mounting plate has a heat dissipation effect, there is no need for the head body to have a heat dissipation effect, and an inexpensive and lightweight resin can be used as the head body material.

[Brief explanation of the drawing]

FIG. 1 is a side view showing a schematic configuration of an optical head according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view showing the vicinity of a semiconductor laser in the embodiment, and FIG. 3 is an exploded perspective view thereof. FIG. 4 is a side view schematically showing a conventional optical disk recording/reproducing device, and FIG. 5 is a schematic side view of a conventional optical head used in the device. 1...Disc, 2...Disc motor, 3...°
Optical head, 4... Transfer unit, 5... Objective lens, 6... Semiconductor laser, 7... Collimator lens, 8... Polarizing prism, 9... Quarter wavelength plate, l
O...actuator, 11...prism, 12.
...Detection lens, 13...Focus detector, 14.
... Tracking error signal and reproduction signal combined detector, 1
5...Head body, 16...Mounting plate, 17.
...Mounting screw, 18...Protrusion, 18A...Outer surface,
19...Opening, 19A...Tip edge, Processing...Coil spring, 21...Adjustment screw.

Claims (2)

[Claims] (1) A head body, a mounting plate that is attached to the head body in an adjustable angle and has a heat dissipation effect, a semiconductor laser fixed to the mounting plate, and a beam emitted from the semiconductor laser that is converted into parallel light. An optical head comprising a collimator lens and an objective lens that images the parallel light onto an information recording medium. (2) The mounting plate has a plurality of coil springs interposed between it and the head body, and is attached to the head body by a plurality of adjustment screws, and the mounting plate further has the semiconductor laser on the head body side surface. The optical head according to claim 1, wherein the optical head has a projection whose diameter gradually decreases toward the tip of the head, and the projection is engaged with an opening formed in the head body. head.