JPH01224720A - Optical pickup - Google Patents

Abstract

PURPOSE:To obtain an optical pickup of less variance and stable quality by reflecting the light once by each of two reflection planes forming a half of a prescribed angle with respect to a reflecting means which changes the advance direction of the light beam emitted from a light source or the reflected light from an optical disk by the prescribed angle. CONSTITUTION:A reflection mirror member 30 is a prism and has a first reflection plane 31 and a second reflection plane 32, and an angle theta1 of crossing between two reflection planes is 45 deg., and two faces 33 and 34 facing these reflection planes are plane and the included angle between these faces 33 and 34 is 90 deg.. The reflection mirror member 30 is stuck and fixed to a base 7 and is so provided that the reflection plane faces the emitting part of a light beam 2 of a light source 1. Though the reflecting mirror member 30 is stuck at an angle theta3 to the base 7, the emission direction of the light beam is fixed as long as the incident light beam comes from the same direction. Thus, a high precision is not required for attachment at the time of sticking and fixing the reflection mirror member 30 to the base 7 to simplify the work, and the performance of the pickup is stabilized and the variance is reduced because the optical path is fixed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical pickup for recording information on or reading information from an optical disc, and relates to a reflecting mirror member that changes the optical path of a light beam.

[Conventional technology]

A cross-sectional view of a conventional optical pickup is shown in FIG.

In the figure, the base 7 of the optical pickup is the optical disc 6.
The optical disk 60 is movable in the radial direction parallel to the disk surface. The base 7 is provided with a drive means (not shown) so that track tracking and access of the disk surface of the optical disk 6 can be performed using a control current. The base 7 also includes a light source 1, a detector (not shown),
It is equipped with optical system components such as a collimator lens and a prism. A reflecting mirror member 37 is adhered and fixed to the base 7 facing the emitting part of the light beam 2 of the light source l, and the reflecting mirror member 37
has an inclination of 45° with respect to the base 7. The light beam 2 is bent at right angles by the reflecting mirror member 37, passes through the objective lens 4, and is irradiated perpendicularly to the disk surface of the optical disk 6.

An actuator 5 equipped with an objective lens 4 is movable in the optical axis direction, and is always in focus on the disk surface of the optical disk 6 by means of a magnetic circuit (not shown) and a coil (not shown) installed in the actuator 5. is controlled by.

In the above configuration, the light beam 2 emitted by the light source 1 becomes parallel to the base 7, has its optical path bent at right angles by the reflecting mirror member 37, passes through the objective lens 4, and is perpendicular to the disk surface of the optical disk 6. reach The light beam reflected from the disk surface of the optical disk 6 passes through the same path and is separated into a recording signal and a control signal to obtain an output. The optical pickup amplifier having this configuration has the advantage that the thickness of the optical pickup can be reduced because the optical beam 2 is bent.

[Problem that the invention seeks to solve]

However, since the optical big amplifier has a reflector member that changes the direction of the light beam, the dimensional accuracy of the reflector member and the base to which it is attached is important, and furthermore, the mounting accuracy when attaching and fixing the reflector member to the base is also important. becomes important.

As shown in FIG. 5, if the mounting angle of the reflecting mirror member deviates from the set value by θ°, the optical axis of the light beam will deviate by 2θ°, and the direction of deviation will not be constant. As a result, the wavefront of the light is tilted and the aberration of the beam spot becomes uneven, resulting in large variations in the performance of the pickup.

Means for Solving Problem C] The reflecting means for optical pink-up according to the present invention is an optical pickup for reproducing or recording an optical disk, and the light beam emitted from the light source or the light reflected from the optical disk travels in the traveling direction. It is characterized by changing the angle to a predetermined angle.

[Effect]

Therefore, if the direction of incidence of the light beam is constant, the traveling direction of the emitted beam will be constant even if the angle changes when mounting the reflecting mirror member, so errors in the mounting can be tolerated.

〔Example〕

Examples according to the present invention are shown in FIGS. 1 and 2a below.

Indicated by b. Portions similar to those in the conventional example are designated by the same reference numerals, and explanations of the same portions will be omitted.

FIG. 1 is a sectional view for explaining the present invention, and FIG. 2a is a cross-sectional view for explaining the present invention.

3b shows the structure of the reflecting mirror member 30, which is a feature of the present invention. The reflecting mirror member 30 is a prism, and has a first reflecting plane 31 and a second reflecting plane 3 as shown in FIG. 2a.
2, and the interlinking angle e1 of the two reflective planes is 45°
It has become. Two surfaces 33 facing each reflective plane
．． 34 is a plane whose angles are right angles. The reflecting mirror member 30 is attached and fixed to the base 7 and is installed so that its reflecting plane faces the emission part of the light beam 2 of the light source 1.

In the above configuration, the light beam 2 emitted parallel to the base 7 enters the plane 33 of the reflection member 30 and enters the first
The light is reflected by a second reflecting plane 31 having an aperture angle of 45° from the reflecting plane, and is emitted from a plane 34. The optical path of this light beam is bent at right angles to the light beam incident on the reflecting mirror member 30.

The light beam emitted from the reflecting mirror member 30 passes through the objective lens 4 and converges on the disk surface of the optical disk 6 at right angles.

The light beam reflected from the optical disk surface passes through the same path and is separated into a recording signal and a control signal to obtain an output.

The angle 02 at which the optical path is bent by the reflecting mirror member 30 is twice the interlinking angle eI of the two reflecting planes 31 and 32 of the reflecting mirror member 30.

In FIG. 2, the angle θ of the reflecting mirror member 30 with respect to the base 7,
This shows the progress of the light beam when the sheets are attached at an angle.According to the law of reflection, the light beam reflected by two reflective planes will exit in a constant direction as long as the incident light beams come from the same direction. In this case, the angle θ2' becomes the same as the angle e2 in FIG. 2a. Therefore, high precision is not required for attachment when attaching and fixing the reflector member 30 to the base 7, which simplifies the work.Furthermore, since the optical path is constant, the performance of the pick amplifier is stabilized and variations are reduced.

As another embodiment, as shown in FIG.
0 may be composed of two reflecting plates 35 and 36.

In the above embodiment, an example was explained in which the optical path is bent at a right angle, but the basic principle of the present invention is to use the traveling direction of the light beam, and the traveling direction of the light beam can be changed to an arbitrary angle.

〔Effect of the invention〕

According to the method of the present invention, if the incident direction of the light beam is constant, the output direction will not change even if the mounting angle of the reflecting mirror member changes, so it is possible to provide an optical pickup with stable quality with little variation. Further, since high dimensional accuracy of the fixing member involved in attaching the reflecting mirror member is no longer required, costs can be reduced and the attachment work becomes simpler.

[Brief explanation of the drawing]

Fig. 1 is a sectional view e showing an embodiment of the present invention, Fig. 2 a,
b is a sectional view of a main part for explaining the present invention in detail, FIG. 3 is a sectional view of a main part showing an application example, and FIG. 4 is a sectional view of a main part showing a conventional example.
The cross-sectional view, FIG. 5, is a diagram showing problems in the conventional example. ■...Light source 2...Light beam 30...Reflector member 4...Objective lens 6...Optical disk patent applicant Nippon Columbia Co., Ltd. J5
me1kari

Claims (1)

[Claims] In a reflecting means for changing the traveling direction of a light beam emitted from a light source or reflected light from an optical disk to a predetermined angle in an optical pickup for reproducing or recording an optical disk, the reflecting means is set at an angle of 1/2 of the angle. An optical pickup using a reflecting means characterized in that reflection is performed once on each of two reflecting planes having angles.