JPH0487031A - Optical pickup device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention focuses a signal light output from a light source on an optical storage medium, and also corrects the positioning error of the signal light based on the reflected light from the optical storage medium. At the same time, the objective lens that converges the signal light and reflected light and the deflection prism that bends the optical axis of the light source to the objective lens are housed in a movable housing separated from the main housing, and this movable housing is used for optical storage. The present invention relates to an optical pickup device that moves in the recording track arrangement direction of a medium.

[Prior Art] An example of the optical system of an optical pickup device used in an optical recording device that records/reproduces information using an optical storage medium or a magneto-optical storage medium is shown in FIGS. 3(a) and 3(b). show. Note that this optical pickup device uses a push-pull method as a tracking error detection method, and a Knifezi method as a focusing error detection method.

In the figure, signal light output from a semiconductor laser element 1 is converted into parallel light by a coupling lens 2,
It enters the polarized beam splinter 3 as P polarized light, and this P polarized light
The polarized signal light passes through the polarization beam splitter 3 and
74 wavelength plate 4.

The P-polarized signal light transmitted through the 174-wave plate 4 is converted into circularly polarized light by the 174-wave plate 4, and then passes through the objective lens 5.
The light is focused and imaged onto the recording surface of the optical disc 6.

The reflected light from the optical disk 6 passes through the objective lens 5 and is converted into a substantially parallel beam, and then enters the quarter-wave plate 4 again. Thereby, the reflected light that has passed through the 174-wavelength plate 4 is converted into linearly polarized light whose orientation is orthogonal to the incident light, and is thereby reflected by the polarizing beam splitter 3.

In this way, the reflected light from the optical disk 6 reflected by the polarizing beam splitter 3 is focused by the lens 7, and approximately half of the light beam is reflected by the splitting mirror 8 constituting the knife beam in the tracking direction T ( That is, the light is incident on a light receiving element 9 for tracking error detection, whose light receiving surface is divided into two in the radial direction of the optical disc 6 (see FIG. 6B).

In addition, the remaining part of the luminous flux focused by the lens 7 is
A light-receiving element 10 for detecting focusing errors, whose light-receiving surface is divided into two by a dividing line parallel to the ridgeline 8a of the split mirror 8.
is incident on the

Then, a tracking error signal is obtained based on the difference between the light receiving signals output from the two divided light receiving surfaces of the light receiving element 9, and the tracking error signal is obtained based on the difference between the light receiving signals output from the two divided light receiving surfaces of the light receiving element 10. A focusing error signal is obtained based on the difference. Furthermore, a reproduced signal from the optical disc 6 is obtained based on the sum of the light-receiving signals of the light-receiving element 9 and the light-receiving element 10.

Further, the objective lens 5 is provided with an objective lens moving mechanism (path shown) for moving the objective lens 5 in the tracking direction and the focusing direction.

Now, in order to access the entire recording surface of the optical disc 6 with the optical pickup device, it is necessary to move the signal light in a direction that traverses concentric or spiral recording tracks formed on the recording surface.

For this purpose, if the entire optical pickup device is mounted on the same traveling body and moved, the weight of the traveling body increases, which impedes miniaturization of the device and also prevents high-speed data access. becomes difficult to realize.

Therefore, an optical pickup device in which the objective lens 5 and the objective lens moving mechanism are separated from other optical system components and only the separated parts are moved has been put into practical use, and an example thereof is shown in FIG.

In the figure, the objective lens 5 and the objective lens moving mechanism are mounted on a movable housing 20, and other optical system components are housed in a main body housing 21. A traveling mechanism 22 is attached, and the optical disc 6 can be moved back and forth in the radial direction.

In addition, a deflection prism 23 mounted on the movable housing 20
is for aligning the optical axes of the main body casing 21 and the objective lens 5. Further, the spindle motor 24 is for rotating and opening the optical disc 6, and the turntable 25 is for transmitting the rotation of the spindle motor 24 to the optical disc 6.

Now, in such an optical pickup device, the traveling mechanism 2
The optical axis of the objective lens 5 and the optical axis of the semiconductor laser element 1 may be misaligned due to errors in the mounting of the deflecting prism 2.
3 is provided with an adjustment mechanism as shown in FIGS. 5(a) and 5(b).

In the figure, the deflection prism 23 is a disc-shaped holding member 2
6, and the surface 26a of this holding member 26 to which the deflection prism 23 is not attached is formed into a spherical surface centered at a point P where the optical axis is incident on the surface of the deflection prism 23.

A hole 27 with a size smaller than the radius of the surface 26a is bored in the bottom surface of the movable housing 20.
a is in contact with the open end of this hole 27. Further, the holding member 26 is fixed to the movable housing 20 with three screws 28, 29, and 30.

Therefore, with the screws 28, 29, and 30 loosened, the position of the deflection prism 23 is adjusted appropriately so that the optical axis of the semiconductor laser element l coincides with the optical axis of the objective lens 5, and after the adjustment, the screws 28, 29. Tighten 30 to fix the deflection prism 23.

In this manner, the optical axis of the semiconductor laser element 1 and the optical axis of the objective lens 5 are made to coincide with each other by adjusting the manner in which the deflection prism 23 is attached.

[Problems to be Solved by the Invention] However, such conventional devices have the following disadvantages.

That is, since the holding member 26 is fixed with the screws 28, 29.30, the shape of the holding member 26 becomes large due to the attachment of the screws 2g, 29.30, and therefore the shape of the movable housing 20 becomes large. This caused an inconvenience.

Furthermore, if the tightening force of the screws 28, 29, 30 becomes large, as shown in FIG. 6, the holding member 26 is deformed by the force, resulting in the inconvenience that adjustment work cannot be performed. Sometimes it happened.

It is also possible to fix the deflection prism 23 to the movable housing 20 by adhesive, but the adhesive used may be deformed when it hardens, or the temperature may change due to the difference in expansion coefficient between the movable housing 20 and the adhesive. This is undesirable because distortion sometimes occurs, which may cause optical axis misalignment.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical pickup device that can reduce the size of a movable housing and suppress distortion when fixed.

[Means for Solving the Problems] The present invention includes a holding member whose bottom surface is formed into a spherical surface centered at the point of incidence of the optical axis on the surface of the deflecting prism, and a holding member for holding the deflecting prism, and a movable housing having a hole therein. a hole that is provided with a radius smaller than the spherical surface of the holding member and whose one open end abuts the spherical surface of the holding member; a screw member that is screwed into the holding member through this hole; and a screw member that is substantially parallel to the spherical surface of the holding member. The head of the screw member is formed in the spherical concave portion of the screw member, and the step portion provided on the movable housing and with which the head comes into contact is provided.

In addition, there is a holding member whose bottom surface is formed into a spherical surface centered at the point of incidence of the optical axis on the surface of the deflecting prism, and a holding member for holding the deflecting prism, and a holding member whose bottom surface is formed into a spherical surface centered on the incident point of the optical axis on the surface of the deflecting prism, and a holding member which is bored in the movable housing and whose radius is smaller than the spherical surface of the holding member. a screw member that is screwed into the holding member through the hole, and a head of the screw member that is formed in a spherical recess that is substantially parallel to the spherical surface of the holding member. and a holding member interposed between the moving case and the moving case, and a stepped portion provided on the moving case and with which the holding member comes into contact.

[Operations] Therefore, since the holding member is fixed with one screw member, the holding member can be made smaller, and the movable housing can be made smaller. Also, the spherical surface of the holding member.

Since the holding member is fixed by sandwiching the stepped portion of the movable housing between the spherical surfaces parallel to the spherical surface, distortion at the time of fixation can be suppressed.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIGS. 1(a) and 1(b) show a deflection prism adjustment mechanism according to an embodiment of the present invention. This embodiment is applied to the same optical pickup device as shown in Fig. 4, and the same parts and corresponding parts as in Figs. 5(a) and (b) are given the same reference numerals. There is.

In the figure, the deflection prism 23 is a disc-shaped holding member 4
0, and the surface 40a of this holding member 40 to which the deflection prism 23 is not attached is formed into a spherical surface centered at a point P where the optical axis is incident on the surface of the deflection prism 23.

Nine holes 41 having a size smaller than the radius of the surface 40a are provided on the bottom surface of the movable housing 20, and the holes 41 have a size smaller than the radius of the surface 40a of the holding member 40.
a is in contact with the open end of this hole 41.

Furthermore, a step 42 communicating with the hole 41 is formed on the bottom surface of the movable housing 20, and a screw member 43 for fixing the holding member 40 is screwed into the bottom of the step 42. ing.

A surface 43a of this screw member 43 that comes into contact with the stepped portion 42 of the head
is formed to form a spherical surface centered on point P, with its surface 43a in contact with step portion 42.

Therefore, with the screw member 43 slightly loosened to the extent that the holding member 40 can be moved, the position of the deflection prism 23 is adjusted as appropriate so that the optical axis of the semiconductor laser element 1 coincides with the optical axis of the objective lens 5. After the adjustment is completed, the screw member 43 is tightened to fix the deflection prism 23.

At this time, since the surface 43a of the head of the screw member 43 is formed into a spherical surface centered on the point P, the surface 43a is
Therefore, when tightening the screw member 43, the holding member 40 does not sometimes move, and stable tightening can be performed.

Further, the thickest step portion 42 is located between the holding member 40 and the head surface 43a of the screw member 43,
Further, since the point P is located on the extension in the direction in which the screw member 43 tightens the holding member 40, it is possible to prevent the holding member 40 from deforming due to the tightening of the screw member 43.

Further, since the adjustment work can be performed with one screw member 43, the adjustment work can be further simplified.

FIG. 2 shows an adjustment mechanism according to another embodiment of the invention. In addition, in the figure, FIG. 1(a).

The same or corresponding parts as in (b) are given the same reference numerals.

In the same figure, a presser member 51 that is inserted into the screw member 50 is disposed between the screw member 50 that fixes the holding member 40 and the stepped portion 42 .

A portion of this holding member 51 that contacts the head 50a of the screw member 50 is formed flat so as to contact the head 50a, and a surface 51a that contacts the end of the stepped portion 42 is formed at a point P.
It is formed into a spherical surface centered on .

Therefore, when tightening the screw member 50 after the adjustment of the deflection prism 23 is completed, the head 50a of the screw member 50 contacts the holding member 51 and slips at the contact portion, so that this tightening may sometimes cause the holding member 40 to rotate. It is possible to avoid such situations and make the adjustment work easier.

Furthermore, in this case, a general-purpose product can be used as the screw member 51, so the cost of the device can be reduced.

Note that the present invention can be similarly applied to optical pickup devices equipped with optical systems other than the optical system described above.

[Effects of the Invention] As explained above, according to the present invention, the holding member and the movable case can be fixed with one screw member, so the holding member can be downsized, and thereby the movable case can be fixed. It is possible to downsize and simplify the adjustment work. In addition, the part sandwiched between the screw member and the holding member is
Since it is the thickest step, it is possible to avoid a situation where the holding member is distorted during adjustment. In addition, since the holding member is interposed between the screw member and the movable housing, the rotational force when tightening the screw member does not act on the holding member, and the adjustment work can be further simplified. .

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are schematic partial sectional views showing an adjusting mechanism according to one embodiment of the present invention, and FIG. 2 is a schematic partial sectional view showing an adjusting mechanism according to another embodiment of the present invention. 3(a) and 3(b) are schematic diagrams illustrating the optical system of an optical pickup device, FIG. 4 is a schematic diagram illustrating an example of an optical pickup device in which only the objective lens is moved, and FIG. 5 ( a) and (b) are schematic partial sectional views showing a conventional example of an adjustment mechanism, and FIG. 6 is a schematic partial sectional view for explaining the disadvantages of the conventional device. 20... Moving housing, 23... Deflection prism, 40...
...Holding member, 41a, 43a, 51a...surface, 42
...Stepped portion, 43.50...Screw member, 51...Press member.

Claims (2)

[Claims] (1) An objective lens that focuses the signal light output from the light source on the optical storage medium and detects the positioning error of the signal light based on the reflected light from the optical storage medium, and converges the signal light and the reflected light. In an optical pickup device, a deflection prism for bending the optical axis of a light source to an objective lens is housed in a movable casing separated from a main casing, and the movable casing is moved in the recording track arrangement direction of an optical storage medium. a holding member for holding the deflection prism, the bottom surface of which is formed as a spherical surface centered on the point of incidence of the optical axis on the surface of the deflection prism; a hole formed so that one open end thereof comes into contact with the spherical surface of the holding member; a screw member that is threadedly engaged with the holding member through the hole; An optical pickup device comprising: a head of a screw member; and a stepped portion provided on a movable casing, with which the head comes into contact. (2) An objective lens that focuses the signal light output from the light source on the optical storage medium and detects the positioning error of the signal light based on the reflected light from the optical storage medium, and converges the signal light and the reflected light. In an optical pickup device, a deflection prism for bending the optical axis of a light source to an objective lens is housed in a movable casing separated from a main casing, and the movable casing is moved in the recording track arrangement direction of an optical storage medium. a holding member for holding the deflection prism, the bottom surface of which is formed as a spherical surface centered on the point of incidence of the optical axis on the surface of the deflection prism; a hole formed in the hole whose one open end abuts the spherical surface of the holding member; a threaded member screwed into the holding member through the hole; and a spherical recess formed in a spherical recess substantially parallel to the spherical surface of the holding member and the screw An optical pickup device comprising: a holding member interposed between the head of the member and a movable casing; and a stepped portion provided on the movable casing and abutted by the holding member.