JPH03147533A - Separable optical head - Google Patents

Abstract

PURPOSE:To prevent dust attached on an optical system in a fixed part by changing the arrangement of the fixed part by reversing the arrangement of the optical system in the fixed part, and evading an air current from a disk as far as possible. CONSTITUTION:The fixed part 31 is arranged being one-sided at the upstream side in a rotational direction of a recording medium traversing an optical path setting the optical path from the fixed part 31 for an objective lens 4 to a movable part 32 as reference. Therefore, the fixed part 31 is separated from the air current discharged from the aperture of the cartridge of the recording medium as far as possible, which prevents the dust on the air current directed to the fixed part 31. Thereby, it is possible to prevent the dust attached on the optical system in the inside of the fixed part 31, and to surely perform servo control and to secure reliability for data.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a separate optical head in a magneto-optical or optical information recording device.

[Prior Art] This type of magneto-optical or optical information recording device can randomly record, reproduce, or erase audio or image information with high performance and high density. The disk-shaped recording medium used here is, for example, transparent acrylic resin,
It has a recording layer on a sheet of transparent polycarbonate or the like, and uses an optical head to form a bit pattern there during recording, which is then read during playback.

The above-mentioned optical head is equipped with various optical systems to perform such recording, playback, and erasing functions, but in order to improve access speed, a separate type as shown in Figure 4 is adopted. It became so. Here, the carriage (movable part) 32 that is moved in the theta direction includes only the objective lens 4, the flip-up mirror 33, and an actuator (not shown) for finely adjusting the objective lens 4 in the focusing direction and the tracking direction. and other optical systems, such as a semiconductor laser 1 as a light source, a collimator lens 2,
A fixed part 31 is equipped with a polarizing beam splitter 3, a condensing lens 5, a second polarizing beam splitter 6, a third polarizing beam splitter 7, a servo sensor 8, an RF sensor 9, 9', and the like. Then, the fixing part 31
The light flux is supplied to the movable part 32 and further to the disk 10 via the objective lens 4, or the reflected light from the disk 10 is sent and received to the mirror 33 via the objective lens 4 and further to the fixed part 31. It has become.

[Problems to be Solved by the Invention] However, as shown in FIG. Due to the arrangement of the optical system, the section 31 is disposed biased toward the downstream side in the rotational direction of the recording medium that traverses the optical path when viewed from above. Therefore, the airflow generated by the rotation of the disk is blown from the cartridge opening of the disk toward the fixing section 31, so that the dust carried by the airflow is directed toward the fixing section 31, There is a risk of it adhering to the glass parts of the optical system. This dust adhesion causes a reduction in the servo signal and RF signal, and also reduces the reliability of data.

[Objective of the Invention] The present invention has been made based on the above circumstances, and by reversing the arrangement of the optical system in the fixed part, the arrangement of the fixed part is changed to avoid air flow from the disk as much as possible. Therefore, it is an object of the present invention to provide a separate optical head that prevents dust from adhering to the optical system within the fixed part.

[Means for Solving the Problems] Therefore, in the present invention, light is focused on the recording medium via a movable part that is movable in the radial direction of a rotating disk-shaped recording medium and an objective lens provided on the movable part. In the separated optical head, the optical head is provided with a fixed part equipped with a light source that provides a light beam for the objective lens. The fixing portion is arranged offset to the side.

[Function] Therefore, since the fixing part is kept as far away as possible from the airflow blown out from the opening of the recording medium cartridge, the debris carried by the airflow will not reach the fixation part. Therefore, it is possible to avoid dust from adhering to the optical system inside the fixed part.

[Example] Hereinafter, an example of the present invention will be specifically described with reference to FIGS. 1 to 3. In the configuration shown here, the same parts as in the conventional example are given the same reference numerals, and the explanation thereof will be omitted. Here, the arrangement of each optical system in the fixed part 31 is completely reversed from that of the conventional example (see Fig. 1).
Therefore, when the optical path from the fixed part 31 to the movable part 32 with respect to the objective lens 4 is taken as a reference, the fixed part 31 is shifted toward the upstream side in the rotational direction (arrow) of the disk 10 that crosses the optical path. (See Figure 3).

In the figure, reference numeral 41 is a linear motor for performing a seek operation on the movable portion 32 movable in the radial direction of the rotating disk-shaped recording medium, and reference numeral 42 is a spindle motor for rotationally driving the disk 10.

The light emitted from the semiconductor laser 1 passes through the collimator lens 2, becomes parallel light, passes through the polarizing beam splitter 3, reaches the flip-up mirror 33, changes the direction of the light, and enters the objective lens 4. The light beam is directed and focused onto the disk 10 to form a desired light beam spot. The reflected light from the disk passes through the same path and enters the polarizing beam splitter 3, where it is polarized and brought to the condensing lens 5, and then passes through each polarizing beam splitter 6.7 to the servo sensor 8 and the RF It is detected by sensor 9.9'. During recording, playback, or erasing operations on a disk, the disk 10 rotates at high speed due to the rotation of the spindle motor 42, so airflow blows out from the opening of the cartridge that houses the disk, moving in the direction of rotation of the disk, and further. It flows in the centrifugal direction (indicated by the arrow in Figure 3). For this reason,
Dust is carried along with the air flow, but unlike the conventional case, the arrangement of the fixed part 1 in the present invention is biased toward the upstream side in the rotational direction, so the dust is not blown directly here. (It is possible to avoid dust from adhering to the optical system.

Although the near motor 41 is used to drive the carriage 32 in this embodiment, it goes without saying that other structures and mechanisms, such as a stepping motor and a swing arm, may be used. Further, although the details of the actuator for controlling the focusing and tracking of the objective lens 4 are not shown, it goes without saying that a known system such as a rotary sliding type or a type using a plate spring can be adopted.

[Effects of the Invention] The present invention has been described in detail above, and by devising the arrangement of the rotating part of the optical head, it is possible to avoid as much as possible the adhesion of dust to the optical system in the fixed part, especially the glass part thereof. , can be reduced, and servo control, data reliability, etc. can be ensured.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of the present invention, FIG. 2 is a perspective view of the same concrete structure, and FIG. 3 is a plan view conceptually showing the main parts.
FIG. 4 is a perspective view of the conventional example, and FIG. 5 is a plan view conceptually showing the main parts. 4... Objective lens 31... Fixed part 32.
...Movable part (carriage) 10...Disk 33...Flip-up mirror

Claims (1)

[Claims] A movable part movable in the radial direction of a rotating disc-shaped recording medium, and a fixed part equipped with a light source that provides a light beam to be focused on the recording medium through an objective lens provided on the movable part. In the separated optical head, the optical path from the fixed part to the movable part with respect to the objective lens is used as a reference.
A separable optical head characterized in that the fixed portion is disposed offset to the upstream side in the rotational direction of the recording medium that crosses the optical path.