JPH0831215B2 - Optical head device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical head device for optically recording or reproducing information.

[Prior Art] In recent years, optical disk devices using laser light have come to be used in various fields such as external memory for computers, video and audio devices. The recording or reproducing head device used in such a device needs to move relative to the disc that is the information recording medium, and also controls focus control and tracking control as well as precise position control. The head device itself must be small and lightweight, and the optical system is required to have high positional accuracy and centering accuracy.

The prior art of such an optical reading head device is described in JP-A-51-97402. This conventional technique will be described with reference to FIG. A beam from a light source such as a He-Ne laser (not shown) goes straight through the opening 102 of the machine frame,
It is bent at a right angle by the half mirror 103, and the total reflection mirror 104
Is reflected at a right angle by and is bent vertically at a right angle by a movable reflecting mirror 105 which is designed to perform tracking by rotation. Then, the surface of the disk 107 of the recording information medium, which is rotated by the motor 110 at high speed, is spotted through the beam focusing device 106 attached to the drive actuator for the two-dimensional objective lens on the machine frame of the block body 111 for mounting the optical element. It is configured to illuminate with light. The reflected light from the surface of the disk 107 passes through the beam converging device 106 again and is collimated into a parallel beam, which is then reflected by the movable reflecting mirror 10.
5 、 Half mirror after being reflected by total reflection mirror 104
The light is transmitted through the semi-transmissive surface of 103 and is incident on the photodetector 108. The prism 103, the mirror 104, the movable reflecting mirror 105, the beam focusing device 106, and the photodetector 108 described above are integrated with a block body to which they are attached to form a block to form a head device.

In the head device of such an optical recording / reproducing apparatus, the number of optical elements is increased, and a deviation due to the temperature of the unit in each part occurs, which causes a problem that astigmatism and coma aberration occur on the disk surface.

In addition, the number of optical elements increases, the size of the entire apparatus becomes large, and the cost becomes high. Further, when the optical members are separated and assembled in the block, there is a drawback that assembly adjustment takes time. Further, the movable reflecting mirror 1 that reflects the emitted light toward the beam converging device 106 and the reflected light toward the total reflection mirror 104.
05 is also inconvenient in terms of assembly work to the block body 111 and manufacturing cost.

[Object] An object of the present invention is to provide an optical head device which eliminates the above-mentioned drawbacks.

[Outline] A semiconductor laser which is an optical type and a light source of the present invention, an objective lens for converging light emitted from the semiconductor laser on a recording medium, and the semiconductor laser arranged in the optical path between the semiconductor laser and the objective lens. A beam splitter that separates the emitted light and the reflected light from the recording medium, a photodetector that receives the reflected light, and a block body that mounts at least the beam splitter, and moves in the tracking direction of the recording medium. In a possible optical head device, which is interposed between the beam splitter and the objective lens and is formed on the optical axis of the objective lens, the emitted light is perpendicular to the objective lens, and the reflected light is Directly
An inclined flat surface for totally reflecting the beam splitter and a mounting seat for mounting the beam splitter are integrally formed with the block body.

[Embodiment] An embodiment of the head device of the optical recording / reproducing apparatus of the present invention will be described with reference to FIG.

The block body 11 of the optical head device 10 is integrally molded of synthetic resin or die casting, and the mounting seats 12 of the prism 1 having a semi-transmissive surface are formed in the center, and the left and right sides of the mounting seats 12 are formed at desired inclination angles. The reflector 2 and the critical angle prism 3 are arranged. In addition, the middle part is a concave notch
15,15 are formed. The prisms 1 are attached to the mounting seats 12 and 14,
The critical angle prisms 3 are attached and fixed by an adhesive.

Above the reflecting portion 2 of the block main body 11, an objective lens 5 and a λ / 4 plate 6 which are attached to a machine frame of a two-dimensional direction objective lens drive actuator (not shown), and above the prism 1 are collimator lenses 4 and λ. / 2 plate 9, collimator lens 4 and semiconductor laser 7 are the same as the critical angle prism 3
The photodetectors 8 are disposed and attached above the respective.

Here, the reflecting portion 2 arranged on the inclined surface of the block body 11 is formed by directly coating the inclined surface of the block body 11 with a multilayer reflective surface. The bottom of the notch 16 'is formed as a diverging surface consisting of a light-scattering surface with small irregularities. The divergent surface diverges stray light generated by the critical angle prism 3.

Now, when laser light is emitted from the semiconductor laser 7, the light is collimated by the collimator lens 4 and passes through the λ / 2 plate 9 and is reflected rightward at a right angle by the semi-transmissive surface of the prism 1 inclined by 45 degrees. Then, it is bent at a right angle in the vertical upward direction by the reflecting portion 2, passes through the λ / 4 plate 6 and is converged by the objective lens 5 to irradiate the surface of the disk 23 as spot light. Then, the light reflected from the disk 23 becomes parallel light again by the objective lens 5, passes through the λ / 4 plate 6 and is bent leftward at a right angle by the reflecting portion 2, passes through the semi-transmissive surface of the prism 1, and becomes a critical light. It enters the prism 3. After being repeatedly reflected three times in the critical angle prism 3, the light is emitted from the exit surface to the photodetector 8 as parallel light, and the signal photoelectrically converted by the photodetector 8 is a reproduction output signal or a focusing error signal. Is output as.

The method for inspecting the block body 11 of the head device 10 thus formed can be performed as follows.

The reference block 30 in FIG. 2 is an optical glass, which is a block body.
It is formed in a trapezoidal shape corresponding to the concave shape on the upper surface of 11, the upper and lower surfaces are perfectly parallel, and the surface 30a of the critical angle prism has an inclination angle.
And the surface 30b having the inclination angle of the total reflection mirror are accurately angled. Then, the reflecting mirror 31 is provided on the upper surface on the surface 30a side.
Is attached.

Now, this reference block 30 is a block body of the head device 10.
The light from the semiconductor laser 33 is made incident on the inclined surface 30b from above by the collimator lens 32 as parallel light and made incident on the inclined surface 30b. Then, the light flux is reflected to the left at a right angle on the inclined surface 30b, is further bent vertically upward on the inclined surface 30a, and is incident on the reflecting mirror 31. The reflected light from the reflecting mirror 31 is reflected again by the inclined surfaces 30a and 30b, passes through the collimator lens 32, and returns to the semiconductor laser 33 as monitor light.
This light is detected by the monitor photodetector 34 on the back of the optical axis of the semiconductor laser 33, whereby the principle is determined by autocollimation. That is, when the accuracy is perfectly obtained, the output of the monitor photodetector 34 becomes maximum,
This makes it possible to determine.

This is because, for example, if the prism mounting seat 12 is in a state where it travels a little upward, the reference block 30 will not be completely inserted and will float and the monitor light will be displaced. Further, the angles of the inclined surfaces 30a and 30b are determined by the reference block 3
Measured mechanically and optically by 0.

With such a simple method, the block body 11 can be inspected quickly, and an optical element such as a prism is simply attached to the block body 11 where the position and angle of the mounting seat are accurately formed with an adhesive, or the reflection is performed. By forming the surface, it is possible to easily manufacture an accurate head device that is centered and adjusted in position.

The above inspection method utilizes the self-coupling effect generated by the light returning to the semiconductor laser 33.
The operation may be performed by disposing 34 at a position different from that of the semiconductor laser 33. This example will be described with reference to FIG. Reference block
Semi-transmissive surface 40c at the center corresponding to 40 prism mounting seats 12
The configuration of the reference block 40 is the second except that the
It is the same as the one in the figure. Then, the monitor photodetector 34 is arranged above the semi-transmissive surface 40c.

Now, when the reference block 40 is inserted into the concave portion of the block body 11 and the light from the semiconductor laser 33 is collimated by the collimator lens 32 and made incident on the inclined surface 40b, it is bent leftward at a right angle on the inclined surface 40b. The luminous flux transmitted through the semi-transmissive surface 40c,
Further, the light is reflected vertically upward by the inclined surface 40a and is incident on the reflecting mirror 31 as parallel light. The light flux reflected from the reflecting mirror 31 is again bent to the right by the inclined surface 40a and reflected by the semi-transmissive surface 40c, and is directed vertically downward at a right angle and passes through the hole 19 provided in the prism mounting seat 12. The light is reflected by the reflecting mirror 35 arranged at the bottom of the block body 11, again passes through the semi-transmissive surface 40c, enters the monitor photodetector 34, and is measured by the detector 34.

[Advantages of the Invention] As described above, according to the optical head device of the present invention, since the mounting seat is integrally molded with the block body by die casting or the like, the work of assembling the optical element such as the beam splitter and the position adjustment are easy. become. Further, since the inclined plane that allows the emitted light to enter the objective lens and allows the reflected light to directly enter the beam splitter is integrally formed with the block body by die casting or the like, the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a head device showing a first embodiment of the present invention, FIG. 2 is a schematic sectional view of an inspection device for explaining an inspection method of the head device of the present invention, and FIG. FIG. 4 is a schematic sectional view of an inspection device for explaining an inspection method different from that of FIG. 4, and FIG. 4 is a schematic perspective view showing a conventional head device. 5 …… Objective lens 7 …… Semiconductor laser 10 …… Head device 11 …… Block body 12,14 …… Mounting seat

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazutake Sugawara 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Co., Ltd. (72) Takeaki Nakamura 2-43 Hatagaya, Shibuya-ku, Tokyo No. 2 in Olympus Optical Co., Ltd. (56) Reference JP-A-57-200001 (JP, A) Jikkoku 57-58576 (JP, Y1)

Claims (1)

[Claims] 1. A semiconductor laser which is a light source, an objective lens for converging light emitted from the semiconductor laser on a recording medium, and an emission lens arranged in an optical path between the semiconductor laser and the objective lens to record the emitted light. An optical system having a beam splitter that separates the reflected light from the medium, a photodetector that receives the reflected light, and a block body that mounts at least the beam splitter, and is movable in the tracking direction of the recording medium. In the expression type head device, it is interposed between the beam splitter and the objective lens, and is formed on the optical axis of the objective lens, the emitted light is perpendicular to the objective lens, and the reflected light is directly
An optical head device characterized in that an inclined plane for totally reflecting the beam splitter and a mounting seat for mounting the beam splitter are integrally molded together with the block body.