JPH059682Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an optical member in an optical playback device having a front-back identification function.

[Conventional technology]

For example, an optical reproducing device for optical discs, magneto-optical discs, etc., uses a grating to separate the light beam from a light source such as a semiconductor laser into multiple light beams in order to detect tracking errors. In order to detect focusing errors, some systems use a cylindrical lens to give astigmatism to the light returned from the disk.

In such an optical reproducing device, it is important to attach optical members such as gratings and cylindrical lenses with their front and back sides correct. For this reason, in the grating, as shown in FIG. 4A, one surface of the grating 1, for example, one side of the grating surface, is chamfered 2, and the chamfered side is placed in a predetermined position with respect to the holding member. The device is oriented so that it points in the direction of In addition, as for the cylindrical lens, as shown in FIG. 4B, a chamfer 4 is similarly applied to one side of one surface of the cylindrical lens 3, and the cylindrical lens 3 is held so that the side with the chamfer 4 faces in a predetermined direction. It is attached to the component. Note that in FIGS. 4A and 4B, grooves may be formed instead of chamfers.

[Problem that the invention attempts to solve]

However, in the case of the optical member in the conventional optical playback device described above, chamfers and grooves are formed by a process different from the process of cutting out the optical member from a large size with many pieces.
There are disadvantages in that it takes many man-hours to manufacture, the setup is complicated, and the optical member itself is expensive.

This invention was made in view of these conventional problems, and aims to provide an optical member for an optical playback device that has a front/back identification function and is appropriately configured to be simple and inexpensive. .

[Means for solving problems]

In order to achieve the above object, this invention makes it possible to identify the front and back sides of an optical member in an optical playback device for reading information on a recording medium in which information is recorded in the form of a track. , they are formed asymmetrically with respect to axes that pass through the optical axis and are orthogonal to each other, and are point symmetrical with respect to the optical axis.

[Action]

With this configuration, by orienting the optical member to form a predetermined shape, it is possible to identify the front and back from the outer shape itself.

〔Example〕

FIGS. 1A and 1B are a front view and a side view showing a first embodiment of this invention. In this embodiment, the grating 11 in the optical reproducing device is formed into a parallelogram when viewed from the optical axis direction, and the surfaces where the acute angle portions 12 and 13 are the upper right and lower left sides are the grating surfaces 14.

In this way, when the grating 11 is viewed from the optical axis direction, if the acute angle portions 12 and 13 are located at the upper right and lower left, the grating plane will always be aligned.
4 is the front surface, so that the front and back sides of the grating 11 can be identified.

As shown in FIG. 2A, the grating 11 is bonded to the positioning square groove 17 having the optical path hole 16 of the holding member 15 so that its acute angle portions 12 and 13 are located at the upper right and lower left. Assemble. When assembled in this manner, the mounting surface of the grating 11 to the holding member 15 is uniquely determined, and as shown in FIG. 2B, the grating surface 14 is always the surface.

3A, B, and C are a perspective view, a front view, and a side view showing a second embodiment of this invention. In this embodiment, a cylindrical lens 21 in an optical reproducing device whose front and back sides have slightly different curvatures is used as a first
As in the embodiment, it is formed into a parallelogram when viewed from the optical axis direction, and the surfaces where the acute angle portions 22 and 23 are at the upper right and lower left are defined as surfaces 24 of predetermined curvature.

Therefore, according to this embodiment, when the cylindrical lens 21 is viewed from the optical axis direction, the acute angle portions 22 and 23 are located at the upper right and lower left, thereby making it possible to form the predetermined curvature surface 24 on the surface. .

Note that this invention is not limited to the above-described embodiments, and can be modified or changed in many ways. For example, the external shape for identifying the front and back is not limited to the above-mentioned parallelogram, but may be asymmetrical with respect to the axes passing through the optical axis and orthogonal to each other when viewed from the optical axis direction, and point symmetrical with respect to the optical axis. For example, it can be of any shape. Furthermore, the optical member mounting surface of the holding member can be matched to the external shape of the optical member, thereby making it possible to more reliably identify the front and back sides of the optical member.

[Effect of idea]

According to this invention, since the external shape itself has the function of identifying the front and back, there is no need for special processing to mark the front and back as in the past.
Therefore, it can be obtained easily and inexpensively.

[Brief explanation of the drawing]

Figures 1A and B are front and side views showing the first embodiment of this invention, and Figures 2A and B are the first embodiment of the invention.
Exploded perspective view and front view showing how the grating is attached to the holding member shown in Figures A and B, 3rd
Figures A, B and C are perspective views, front views and side views showing a second embodiment of this invention; Figures 4A and B
1A and 1B are diagrams showing conventional techniques, respectively. 11... Grating, 12, 13... Acute angle portion, 14... Grid surface, 15... Holding member, 16
...Optical path hole, 17...Square groove for positioning, 21...
... Cylindrical lens, 22, 23 ... Acute angle portion, 24 ... Predetermined curvature surface.

Claims (1)

[Scope of utility model registration request] In an optical member in an optical reproducing device for reading information from a recording medium on which information is recorded in a track shape, the outer shape as seen from the optical axis direction is defined by axes that pass through the optical axis and are orthogonal to each other so that the front and back sides can be distinguished. 1. An optical member in an optical reproducing device, characterized in that the optical member is formed asymmetrically with respect to each other and point symmetrical with respect to an optical axis.