JP2783873B2 - Separate optical head - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a separation type optical head in a magneto-optical or optical information recording device.

[Prior Art] With this type of magneto-optical or optical information recording device, it is possible to record, reproduce, or erase voice or image information at high performance and high density at random. The disk-shaped recording medium used here has a recording layer on a disk made of, for example, a transparent acrylic resin or a transparent polycarbonate, and by using an optical head, a pit pattern is formed thereon during recording, and this is formed during reproduction. I read it.

The above-mentioned optical head has various optical forms in order to perform such recording, reproducing and erasing functions. In order to improve the access speed, a separate type as shown in FIG. 4 is employed. It became so. Here, the carriage (movable portion) 32 operated in the seek direction includes only the objective lens 4, the flip-up mirror 33, and an actuator (not shown) for fine adjustment of the objective lens 4 in the focus direction and the tracking direction. And other optical systems, for example, a semiconductor laser 1 as a light source, a collimator lens 2, a polarizing beam splitter 3, a condenser lens 5, a second polarizing beam splitter 6, a third polarizing beam splitter 7, a servo sensor 8. , And the RF sensors 9 and 9 ′ are mounted on the fixed part 31. Then, through the optical path window, the input / output surface (a) of the flip-up mirror 33 and the polarization beam splitter 3
The light flux from the fixed part 31 to the movable part 32 via the optical path between the input / output surface (b) and the disk via the objective lens 4
The light supplied to the optical disk 10 or reflected from the disk 10 is transmitted to and received from the mirror 33 via the objective lens 4 and further to the fixed portion 31.

[Problems to be Solved by the Invention] However, as shown in FIG. 5, in the conventional separation type optical head, when the optical path from the fixed part 31 to the movable part 32 to the objective lens 4 is used as a reference, the fixed The unit 31 is arranged so as to be offset toward the downstream side in the rotation direction of the recording medium that crosses the optical path in a plan view due to the arrangement of the optical system. For this reason, the air flow generated by the rotation of the disk from the cartridge opening of the disk
Since the air blows toward the fixed portion 31, the dust on the air flow may be directed to the fixing portion 31 and adhere to the glass portion of the optical system provided here. The adhesion of dust causes a reduction in servo signals and RF signals, and lowers data reliability.

[Object of the Invention] The present invention has been made based on the above circumstances, and the arrangement of the fixing unit is changed by inverting the arrangement of the optical system in the fixing unit so that the airflow from the disk can be reduced as much as possible. Accordingly, it is an object of the present invention to provide a separation type optical head which prevents dust from adhering to an optical system in a fixed portion.

[Means for Solving the Problems] For this reason, according to the present invention, a movable portion movable in a radial direction of a disk-shaped recording medium that rotates in one direction and an objective lens provided on the movable portion are used to attach the recording medium to the recording medium. A fixed portion provided with a light source for providing a light beam for condensing light, a rotation direction of the recording medium traversing the optical path with respect to the optical path from the fixed portion to the movable portion with respect to the objective lens. The above-mentioned fixing portion is arranged to be offset on the upstream side of.

[Operation] Therefore, the fixing portion is kept as far as possible from the airflow blown from the opening of the cartridge of the recording medium, and is avoided, so that the dust riding on the airflow is directly applied to the fixing portion. It is not directed, so that the adhesion of dust to the optical system inside the fixed portion can be avoided.

Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG. 1 to FIG. In the configuration shown here, the same portions as those of the conventional example are denoted by the same reference numerals, and description thereof will be omitted. Here, the arrangement of each optical system in the fixed portion 31 is completely inverted from that of the conventional example (see FIG. 1), and therefore, the optical path from the fixed portion 31 to the movable portion 32 with respect to the objective lens 4 is referred to. In this case, the fixing portion 31 is offset toward the upstream side in the rotation direction (arrow) of the disk 10 traversing the optical path (see FIG. 3).

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

Then, the light emitted from the semiconductor laser 1 passes through the collimator lens 2 to become parallel light, reaches the flip-up mirror 33 via the polarization beam splitter 3, and changes the light direction to the objective lens 4. It is directed and focused on the disk 10 to form a desired light beam spot. Then, the reflected light from the disk passes through the same path and enters the polarization beam splitter 3, where it is polarized and brought to the condensing lens 5, and is transmitted through the polarization beam splitters 6 and 7 to the servo sensor 8 and RF. It is detected by the sensors 9, 9 '. At the time of recording, reproducing or erasing operation on the disk, the disk 10 rotates at a high speed by the rotation of the spindle motor 42, so that an air flow blows out from the opening of the cartridge containing the disk, and further in the rotational direction of the disk. It flows in the centrifugal direction (indicated by the arrow in FIG. 3). For this reason, dust is carried on the air flow, but unlike the conventional case, the arrangement of the fixing portion 1 in the present invention is biased toward the upstream side in the rotation direction, so that the dust is directly blown onto the portion. Therefore, the adhesion of dust to the optical system can be avoided.

Although the linear 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, an actuator for focusing and tracking control of the objective lens 4 is not described in detail, but it is needless to say that a known method such as a rotary sliding type or a type using a leaf spring can be employed.

[Effects of the Invention] The present invention has been described in detail above. By devising the arrangement of the rotating portion of the optical head, it is possible to avoid the attachment of dust to the optical system in the fixed portion, particularly to the glass portion as much as possible. And servo control, data reliability, and the like can be ensured.

[Brief description of the drawings]

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

Claims (1)

(57) [Claims] A movable part movable in a radial direction of a disk-shaped recording medium rotating in one direction, and a light source for providing a light beam for condensing the recording medium via an objective lens provided on the movable part. In the separation type optical head having the fixed portion provided, the fixed portion is shifted to the upstream side in the rotation direction of the recording medium across the optical path with respect to the optical path from the fixed portion to the movable portion with respect to the objective lens. A separate type optical head characterized by being arranged in a position.