JP2001084633A - Optical head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical head setting optical power of an LD with emitted light quantity from an objective lens by suppressing a stray beam in the vicinity of the objective lens. SOLUTION: This optical head is provided with an emission means 2 emitting a light beam for reading the data recorded on an optical disk, a condenser means 5 condensing the light beam emitted from the emission means 2 for the optical disk and a yoke 6 holding the condenser means 5, and the yoke 6 is provided with an opening part 7a having a prescribed opening limit for passing the light beam emitted by the emission means 2 to the condenser means 5 through.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an improvement of an optical head in an optical disk device. In particular, the present invention relates to improvement of a yoke provided in an optical head.

[0002]

2. Description of the Related Art L of an optical head composed of a finite optical system is described.
In general, the optical power of D (Laser Driver) is adjusted based on the emitted light amount of the LD itself. That is, the optical power of the LD is not adjusted based on the amount of light after passing through the objective lens. For this reason, when a predetermined level of emitted light quantity is obtained, the current value of the LD at this time is recorded, and when the LD is incorporated in an optical disc device, the optical power of the LD is set based on the current value, and the LD power is set. Is performed.

[0003]

In the above-described method of adjusting the LD, the reliability of the set optical power is low, and the amount of light emitted from the objective lens is directly meaningless. Also,
When the recorded current value is lost, or when a problem occurs in the optical head, there is a problem that it is not possible to take measures in a manufacturing process or an inspection process.

When the light power of the LD is not set based on the amount of light emitted from the LD itself, L is determined by the amount of light emitted from the objective lens.
Although the light power of D is set, the light emission amount of the LD itself greatly fluctuates, and also the signal detection greatly fluctuates.

An object of the present invention has been made in view of the above circumstances, and it is possible to suppress stray light near an objective lens and to set the optical power of an LD by the amount of light emitted from the objective lens. To provide a simple optical head.

[0006]

In order to solve the above-mentioned problems and achieve the object, an optical head according to the present invention is configured as follows.

(1) Emission means for emitting a light beam for reading data recorded on an optical disc, condensing means for condensing the light beam emitted by the emission means on an optical disc, A yoke for holding the unit, wherein the yoke has an opening with a predetermined opening restriction for allowing the light beam emitted by the emitting unit to pass through the light collecting unit.

(2) Emission means for emitting a light beam for reading data recorded on an optical disk, reflection means for reflecting the light beam emitted by the emission means in a predetermined direction, and reflection by the reflection means And a yoke for holding the light-collecting means. The yoke allows the light beam reflected by the reflection means to pass through the light-collecting means. An aperture having a predetermined aperture limit for the light source, wherein the predetermined aperture restriction is an aperture restriction for directly blocking the light beam reflected by the reflection means other than the light beam reaching the light collection means. is there.

(3) Emission means for emitting a light beam for reading data recorded on an optical disk, reflection means for reflecting the light beam emitted by the emission means in a predetermined direction, and reflection by the reflection means And a yoke for holding the light-collecting means. The yoke allows the light beam reflected by the reflection means to pass through the light-collecting means. An aperture having a predetermined aperture limit for the light source, wherein the predetermined aperture restriction is an aperture restriction for directly blocking the light beam reflected by the reflection means other than the light beam reaching the light collection means. There is an aperture limit with a certain margin.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a schematic configuration of an optical head having a finite optical configuration according to the present invention.

The optical head shown in FIG. 1 is a CD (Compact).
Disk) is mounted on an optical disk device for reproducing the optical disk 1. As shown in FIG. 1, the optical head includes a hologram LD unit 2, a rising mirror 3, a lens holder 4, an objective lens 5, a yoke 6, and the like. The yoke 6 is provided with an opening 7a with an opening restriction. The yoke 6 holds the objective lens 5 as shown in FIG.

Reading of data recorded on the optical disk 1 is performed by a light beam emitted from the hologram LD unit 2. That is, the light beam emitted from the hologram LD unit 2 is reflected by the rising mirror 3, passes through the opening 7 a, passes through the objective lens 5 attached to the lens holder 4 in the yoke 6, and
Is irradiated.

The optical head shown in FIG. 1 is for data reading, and has a finite optical configuration for cost reduction. A finite optical head is different from an infinite optical head (which converts a diffused light of an LD into parallel light and is used), which is often employed in a recordable optical head, and generates a large amount of stray light due to reflection of the inner surface of the head inside the optical head. Has features that occur.

Here, with reference to FIG. 3, problems in the conventional optical head will be described. As shown in FIG. 3, the light emitted from the hologram LD unit 12 is
The light is reflected by the rising mirror 13, passes through the opening 17, and
The optical disk is irradiated through an objective lens 15 attached to a lens holder 14 in a yoke 16. At this time, the light not incident on the objective lens 15 (the stray light B in FIG. 1)
Although 5) occurs slightly, the light not incident on the objective lens 15 is required when the objective lens 15 is shifted in the tracking direction by an actuator (not shown). The light (normal light B3 in FIG. 1) that has passed through the objective lens 15 is focused on the optical disk 11, and the intensity of the reflected light is read by a light detector (not shown) in the hologram LD unit 12. Recognized as data.

In a CD optical pickup, an appropriate LD is used to read data recorded on an optical disc.
It is necessary to set the power. This setting can be made by measuring the light emitted from the objective lens 15.
However, when measuring the light emitted from the objective lens 15, it is not always the case that only the regular light B3 emitted from the objective lens 15 is measured. Since the light emitted from the LD spreads radially with a spread angle of about 30 degrees, a part of the light is reflected in the housing formed by the yoke 16 and becomes stray light B4.
In some cases, the light passes through the objective lens 15. Since the angle at which the stray light B4 enters the objective lens 15 is not correct, no image is formed on the optical disc 11, and even if reflected, the stray light B4 does not return to the photodetector in the LD unit 12, so that no problem occurs.

However, the above-mentioned stray light B4 and stray light B5
Is added to the light amount (normal light B3) actually measured when the light amount on the surface of the optical disk 11 is measured by a power meter or the like, and the actual light amount (light amount of the normal light B3) is measured. This allows correct measurement (regular light B3
), It may not be possible to set an accurate LD power.

The optical head according to the present invention is configured as shown in FIG. 1 in order to solve the above-mentioned problems.
That is, the configuration is such that unnecessary light generated as stray light is removed. As shown in FIG. 1, the yoke 6 is provided with an opening 7a with an opening limit for taking in the light emitted from the LD, but the opening 7a is limited to a predetermined size through which unnecessary light does not pass. Thereby, stray light generated near the objective lens 5 is blocked. In other words, of the light beams emitted from the laser LD unit 2 and reflected by the rising mirror 3 in a predetermined direction, those other than the light beam (regular light such as B3 shown in FIG. 1) that directly reaches the objective lens 5 Light beam (unnecessary light such as stray light B4 and B5 shown in FIG. 1)
The opening 7a is provided with an opening restriction for blocking the opening.

As shown in FIG. 2, the yoke 6 may be provided with an opening 7b with a limited margin having a predetermined margin. As shown in FIG. 2, the opening diameter of the opening 7b is set to a size that does not cause any problem even if the actuator moves in the track direction, for example, ± 0.5 [mm].

Since the yoke 6 always needs an opening for taking in light, processing this opening is more cost-effective than having an opening restriction between the hologram LD unit 2 and the rising mirror 3. There is. As a result, the light quantity measurement on the objective lens 5 can be accurately performed, and as a result, the power of the LD can be accurately set.

The optical head according to the present invention employs the yoke 6 having the aperture limit opening 6a as shown in FIG. 1 or the aperture limit aperture 7b having a predetermined margin as shown in FIG. In addition, stray light near the objective lens 5 can be suppressed, and as a result, the amount of light emitted from the hologram LD unit 2 can be set based on the amount of light emitted from the objective lens 5. This makes it possible to suppress variations in the detection signal, thereby providing an optical head that is electrically and reliably stable.

[0022]

According to the present invention, it is possible to provide an optical head capable of suppressing stray light near the objective lens and setting the optical power of the LD with the amount of light emitted from the objective lens.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic configuration of an optical head according to the present invention.

FIG. 2 is a view for explaining that a predetermined margin is given to an opening limit of an opening provided in a yoke of the optical head of the present invention.

FIG. 3 shows a schematic configuration of a conventional optical head,
FIG. 3 is a diagram for explaining a stray light generation mechanism.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical disk 2 ... Hologram LD unit 3 ... Stand-up mirror 4 ... Lens holder 5 ... Objective lens 6 ... Yoke 7a ... Opening with restriction | limiting 7b ... Opening with restriction | limiting with predetermined margin B1, B3 ... Regular light B2 , B4, B5 ... Stray light

Claims (3)

[Claims] An emitting unit for emitting a light beam for reading data recorded on an optical disk; a focusing unit for focusing the light beam emitted by the emitting unit on the optical disk; An optical head comprising: an opening having a predetermined aperture limit for allowing the light beam emitted by the emission unit to pass through the light collection unit. . 2. An emitting means for emitting a light beam for reading data recorded on an optical disk; a reflecting means for reflecting the light beam emitted by the emitting means in a predetermined direction; A light collecting means for condensing the light beam on the optical disk, and a yoke for holding the light collecting means, wherein the yoke allows the light beam reflected by the reflecting means to pass through the light collecting means. An opening having a predetermined aperture limit of the above, the predetermined aperture limit is directly out of the light beam reflected by the reflection means,
An optical head having an aperture limit for blocking light other than the light beam reaching the light condensing means. 3. An emitting means for emitting a light beam for reading data recorded on an optical disk, a reflecting means for reflecting a light beam emitted by the emitting means in a predetermined direction, and a light reflected by the reflecting means. A light collecting means for condensing the light beam on the optical disk, and a yoke for holding the light collecting means, wherein the yoke allows the light beam reflected by the reflecting means to pass through the light collecting means. An opening having a predetermined aperture limit of the above, the predetermined aperture limit is directly out of the light beam reflected by the reflection means,
An optical head, which is an aperture limit that blocks light beams other than the light beam that reaches the condensing means, and has an aperture limit having a predetermined margin.