JPH0590619U - Optical head - Google Patents

Abstract

(57) [Summary] [Purpose] In an apparatus for optically recording or reproducing information, the shape of the holder of the optical component of the optical head or the inner diameter of the optical path hole makes it difficult for unwanted light to enter the photodetector. The purpose is to [Structure] By forming a female screw 3 on a holder 2 of an optical component forming an optical head or an inner wall of an optical path hole, unnecessary light 5 entering the optical path is reflected on the inner wall and is incident on a photodetector 6. It is possible to obtain an optical head in which the S / N ratio is prevented from decreasing.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an optical head of a device for optically recording and reproducing information such as a video disc player and an optical disc device.

[0002]

[Prior Art]

 In an optical device for recording or reproducing information, the optical head has many optical components attached via a holder or directly attached to the base.

A conventional optical head device will be described below with reference to the drawings. FIG. 3 shows the structure of a conventional optical head device. Reference numeral 7 denotes a semiconductor laser which serves as a light source, a beam is diffracted by a grating 8, a part of the beam is reflected by a half mirror 9, and a laser mirror 10 is provided. The beam toward the information medium 11. A collimator lens 12 collimates the beam into parallel light, and an objective lens 13 focuses the information medium 11. The beam reflected by the information medium 11 returns along the same optical path and enters the half mirror 9. A part of the beam is transmitted by the half mirror 9 and enters the photodetector 6 through the concave lens 1.

With the optical system configured as described above, it is required to finally transmit the signal detected by the information medium 11 to the photodetectors 6 as accurately as possible. However, as shown in FIG. 2, the inner diameter of the holder 2 of the optical component (concave lens) 1 is a smooth surface, and unnecessary light 5 other than the original signal light is also reflected by the inner wall of the holder 2 to the photodetector 6. Since the light is incident, the unnecessary light 5 may be superimposed on the original signal and the S / N may be lowered.

[0005]

[Problems to be solved by the device]

 However, as described above, since the inner diameter wall of the optical path hole of the conventional optical head is a smooth surface, unnecessary light other than the original signal light is also reflected by the inner diameter wall and is incident on the photodetector while being superimposed on the original signal. , The signal S / N may be reduced.

The present invention solves the above-mentioned conventional problems, and aims to realize the shape of the inner wall of the optical path hole by a simple construction method such that even if unwanted light enters, it is difficult to enter the photodetector. .

[0007]

[Means for Solving the Problems]

 To achieve this purpose, a female screw is formed on the inner wall of the optical path hole of the optical head of the present invention so that the reflected light does not enter the photodetector even if unwanted light enters.

[0008]

[Action]

 In the present invention, by forming the inner wall of the optical path hole of this shape, the unwanted light incident on the optical head optical path of the present invention is reflected by the slant surface of the internal thread of the inner wall and made incident on the photodetector. It will be diffused.

[0009]

【Example】

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In FIG. 1, 1 is a concave lens, 2 is a holder for the concave lens 1, 3 is a screw formed on the inner diameter wall of the holder 2, and 4 is signal light reflected from an information recording medium (not shown). Reference numeral 5 indicates unnecessary light, and 6 indicates a photodetector.

In the optical head having the shape of the inner wall of the optical path hole configured as described above, the mechanism for preventing the unwanted light 5 from entering the photodetector 6 will be described. A signal is recorded on an information recording medium (not shown). The signal light 4 that has detected and returned returns to the photodetector 6 through the concave lens 1 and transmits the signal. On the other hand, when the unwanted signal 5 different from the original signal beam 4 enters the optical path, the unwanted signal 4 is formed on the inner wall of the holder 2 and is reflected by the inclined surface of the screw 3 and diffused, so that the photo detector 6 is not affected. Can be prevented from entering.

[0012]

[Effect of the device]

 As described above, according to the present invention, it is possible to prevent the signal S / N from being lowered due to unnecessary light by cutting an easily formed internal thread on the inner wall of the optical path holder or the optical path hole. The formed screw can also be used as a screw for fixing an optical component.

[Brief description of drawings]

FIG. 1 is a sectional view of a concave lens portion in the present invention.

FIG. 2 is a sectional view of a conventional concave lens portion.

FIG. 3 is a configuration diagram of an optical part of a conventional optical head device.

[Explanation of symbols]

 1 concave lens 3 female thread 5 unwanted light 6 photo detector

Claims (1)

[Scope of utility model registration request] 1. An optical head of an apparatus for optically recording or reproducing information using an information recording medium, wherein a female screw is formed on either the holder of an optical component or the inner diameter of an optical path hole. Characteristic optical head.