JPH05181083A - Beam irradiating device - Google Patents

Abstract

PURPOSE:To prevent the effect of out-of-focus caused by stray light and the turbulence of irradiating light in a beam irradiating device where the reflected light of a beam emitted from a fixed part and a beam made incident on a movable part by a cover plate is directed at a specified angle against an optical axis. CONSTITUTION:This device is constituted of the fixed part 2 where the beam is emitted from a light source 4 and the movable part 3 which receives the beam emitted from the fixed part 2 and projects it to the outside. 1) At least either of 1st and 2nd light transmissive cover plates 18, 19 provided at an emitting port 6 and an incident port 9 is inclined at the specified angle with respect to the surface vertical to the optical axis of the beam. 2) At least either of 3rd and 4th light transmissive cover plates 28, 29 provided at the emitting port 6 and the incident port 9 is formed of a hologram plate so that transmitted light is transmitted in parallel with the optical axis and the reflected light is reflected in the direction of the specified angle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beam irradiating device such as an optical information recording / reproducing device which is separated into a fixed part and a movable part, and more particularly to a cover plate for a beam emitted from the fixed part or a beam incident on the movable part. The present invention relates to a beam irradiation device capable of reflecting reflected light at a predetermined angle with respect to the optical axis.

Recently, a CD has been used as an optical information recording / reproducing apparatus.
An optical disk device using a ROM, a write-once optical disk device, a magneto-optical disk device, etc. are widely used. In such a device, a small light beam spot is emitted onto a CD, for example.
-A medium such as a ROM is irradiated to reproduce information on the medium or record information on the medium, and the weight of the optical head which moves when accessing this information is usually 70 to
It weighs as much as 80 grams, and as a result, access time is 4 to 5 times longer than that of a magnetic disk device even if the device has the same disk size.

For this reason, a fixed part and a movable part are separately provided, and an optical component such as a laser diode (hereinafter referred to as LD) and a beam splitter and a photodetector are mounted on the fixed part, and an optical actuator and a rising mirror are mounted on the movable part. ,
The moving parts are lightened.

However, since the fixed part and the movable part are separated from each other, the access space of the movable part becomes an air flow space, and there is a concern that the optical parts are contaminated. A method of attaching a cover glass has been proposed.

However, when the cover glass is attached, the reflected light from the cover glass becomes stray light, which has the adverse effect of deviating the focus position of the servo signal and disturbing the read signal, and at a cost, AR (anti-reflecting) is required. ) Even if the coating treatment is performed, the influence still remains and defocusing and disturbance of the irradiation light occur. Therefore, a method for preventing these is desired.

[0006]

2. Description of the Related Art A separation type optical disk device is described in Japanese Patent Application No. 03-039143 by the present applicant, and a conventional example will be described below with reference to FIGS. 5 is a perspective view showing the separation type optical disk device, FIG. 6 is a side view showing an outline of the optical head, and FIG. 7 is a control block diagram.

As shown in FIGS. 5 and 6, the optical head 1
Consists of a fixed part 2a and a movable part 3a. The fixed portion 2a is composed of an LD 4a which is a light source and a collimator lens 5, and has an exit 6a.
have.

The movable part 3a is equipped with an actuator 7 having an objective lens 8 and a reflection mirror 10, and has a carriage 11 having an entrance 9a and guide shafts 13a and 13b fitted into sliding holes 12a and 12b of the carriage 11. And the coils 15a and 15b and the iron cores 16a and 16b, the electromagnetic circuit 14a, which moves the carriage 11 in the directions of arrows A and B by energizing the coils 15a and 15b.
It consists of 14b and.

A spindle motor M having a turntable 17 is arranged on the left side of the movable portion 3a in the figure,
An optical disk 20 is set on the turntable 17. The actuator 7 is controlled by a track control circuit 25 and a focus control circuit 24, which will be described later, and moves the objective lens 8 on the carriage 11 in the XY directions to position and focus a track on the optical disk 20.

Further, a cover glass plate 18a, 19a formed of a transparent material having the same thickness, such as a transparent glass plate, is attached to the exit port 6a and the entrance port 9a, and dust is emitted from the exit port 6a.
And the LD 4a and the collimating lens 5 penetrating from the entrance 9a.
It also prevents the reflection mirror 10 from becoming dirty. The cover glass plates 18a and 19a are AR-coated to prevent light reflection.

A servo circuit as shown in FIG. 7 is connected to such an optical head 1 to perform various servo controls. The servo circuit includes an LD control circuit 21, a track control circuit 22, a track drive unit 23, a focus control circuit 24, and a focus drive unit 25.

The LD control circuit 21 drives the LD 4a and measures the LD 4a measured by a detector (not shown).
The amount of light is adjusted to a predetermined amount. The track control circuit 22 is
The track drive unit 23 positions the track on the optical disc 20. In this case, the track control circuit 22 uses the track error signal (TES) from the optical head 1.
Is input, and servo control is performed so that this signal falls within a predetermined range.

The focus control circuit 24 controls the focus drive section 25 to drive an optical lens or the like,
Focus on. In this case, the focus control circuit 24
Then, the focus error signal (FE
S) is input and servo control is performed so that this signal falls within a predetermined range.

With such a configuration and function, when recording or reproducing information on the optical disk 20, the carriage 11 is turned by the electromagnetic circuits 14a and 14b.
It is moved below the optical disk 20 set on top.

Next, the laser beam emitted from the LD 4a passes through the collimating lens 5 and exits horizontally from the exit 6a, enters through the entrance 9a of the carriage 11, and is reflected by a reflection mirror.
Reflecting at 10 and rising, illuminating the surface of the optical disk 20 through the objective lens 8, positioning the optical disk 20 on the track by moving the actuator 7 and focusing by moving the objective lens 8, and then recording information. Alternatively, reproduction is performed.

[0016]

According to the above-mentioned conventional method, dust-proof cover glasses are attached to the exit of the fixed part and the entrance of the movable part, respectively. Generally, about 5% of the light is reflected on the surface of the optical component without the AR coating treatment, and the reflected light becomes stray light and adversely affects the servo signal and the read signal, so that the AR coating treatment is performed.

The cover glass plate is also AR-coated, but this AR-coating not only increases the cost, but also leaves a reflectance of about 0.5% and has a bad effect. Therefore, as shown by the broken line in FIG. 8, the stray light reflected by the cover glass plate deteriorates the signal quality. That is, the focus position of the servo signal originally obtained is deviated due to stray light and blurred, and recording and reproduction cannot be performed at a desired position.

Stray light returns to the LD, which is the light source, and L
The change of the light quantity of the beam emitted from D and the light quantity distribution are disturbed, and the reading becomes impossible. There is a problem.

It is an object of the present invention to provide a beam irradiation device capable of reducing the adverse effects of stray light and preventing the effects of defocusing, irradiation light disturbance, and the like.

[0020]

FIG. 1 is a principle view of the present invention, (a) is a side view corresponding to claim 1, and (b) is a side view.
It is a side view corresponding to. 1) Means corresponding to claim 1 In FIG. 1 (a), 4 is a light source, 2 is a fixed part that emits a beam from a light source 4 provided inside, and 3 is a beam that is received from the fixed part 2. And 6 are provided in the fixed part 2 to emit a beam, 9 is provided in the movable part 3 to receive a beam, and 18 is a light-transmissive material. The first cover plate formed to have a size that closes the opening 6, and 19 is a material having a light-transmitting property.
It is the 2nd cover plate formed in the size which closes up.

At least one of the first cover plate 18 and the second cover plate 19 is configured to be inclined at a predetermined angle with respect to a plane perpendicular to the optical axis of the beam. 2) Means corresponding to claim 3 In FIG. 1 (b), 4 is a light source, 2 is a fixed part which emits a beam from a light source 4 provided inside, and 3 is a light beam which is emitted from the fixed part 2. And 6 are provided in the fixed part 2 to emit the beam, 9 is provided in the movable part 3 to enter the beam, and 28 is a light-transmitting material. A third cover plate formed to have a size that closes the opening 6, and 29 is a material having a light-transmitting property.
It is a fourth cover plate that closes the entrance 9 formed in the size of.

At least one of the third cover plate 28 and the fourth cover plate 29 is formed of a hologram, and the transmitted light of the beam is transmitted along the optical axis, and the reflected light is predetermined with respect to the optical axis. It is configured to reflect at an angle.

[0023]

1) Operation corresponding to claim 1 The beam emitted from the light source 4 is the first cover plate of the emission port 6.
The first cover plate 18 and the second cover 18 which are transmitted through 18 and emitted, and then transmitted through the second cover plate 19 of the entrance port 9 and incident, are inclined at a predetermined angle with respect to a plane perpendicular to the optical axis of the beam. Board 19
Since the reflected light reflected on at least one of the two travels in a direction different from the outgoing light and the incident light without entering the optical axis direction of the beam, it is possible to prevent the reflected light from becoming stray light and entering the light source 3 again. Therefore, it is possible to prevent deterioration of signal quality due to stray light. 2) Action corresponding to claim 3 The beam emitted from the light source 4 is the third cover plate of the emission port 6.
Although it passes through 28 and goes out, it goes through the 4th cover plate 29 of the entrance 9 and enters, but at least one hologram of the 3rd cover plate 28 and the 4th cover plate 29 formed by the hologram The transmitted light of the transmitted beam is transmitted along the optical axis,
Since the reflected light is reflected at a predetermined angle with respect to the optical axis and travels without entering the direction of the optical axis of the beam, the reflected light can be prevented from entering the direction of the light source 3 again as stray light. It is possible to prevent quality deterioration.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. 1) Description of First Embodiment An embodiment corresponding to claims 1 and 2 will be described with reference to the side views and the explanatory views of FIGS. 2 and 3. The same reference numerals denote the same objects throughout the drawings.

The LD 4a, the cover glass plate 18a and the cover glass plate 19a in FIG. 2 are the light source 4 and the first cover plate 18 in FIG.
And the second cover plate 19 respectively. As shown in the side view of FIG. 2, cover glass plates 18a, 19a are attached to the light exit 6a of the fixed part 2a and the light entrance 9a of the carriage 11 of the movable part 3a by L.
The beams emitted from D4a are attached to the plane perpendicular to the optical axis so as to be inclined downwards with respect to each outside by an angle θ (for example, θ≈1.5 degrees).

With such a structure, as shown in FIG. 3, the beam emitted from the LD 4a passes through the cover glass plate 18a of the emission port 6a and is emitted, and passes through the cover glass plate 19a of the incident port 9a. However, the reflected light reflected by the cover glass plate 18a and the cover glass plate 19a inclined by a predetermined angle θ, that is, stray light, does not enter the optical axis direction of the beam.

Since the cover glass plate 18a and the cover glass plate 19a are inclined in the opposite directions by the same angle θ, the optical axis shift amount and the astigmatism are canceled out. Moreover, since the cover glass plates 18a, 19a are inclined downward with respect to the outer sides of the exit port 6a and the entrance port 9a, it becomes difficult for dust to adhere and the adhesion of dust is reduced, so that the amount of light emitted from the LD 4a is reduced. Can be prevented from being damped by. 2) Description of Second Embodiment An embodiment corresponding to claim 3 will be described with reference to the side view of FIG.

The LD 4a, the hologram plate 28a, and the hologram plate 29a in FIG. 4 correspond to the light source 4, the third cover plate 28, and the fourth cover plate 29 in FIG. 1, respectively. 4 is different from the embodiment described with reference to FIGS. 2 and 3, but the cover glass plate 18
The hologram plate is used instead of the structure in which a and 19a are inclined.

That is, as shown in FIG. 4, the hologram plates 28a and 29a are closely attached to the exits 6a of the fixed part 2a and the entrances 9a of the carriage 11 of the movable part 3a on the surfaces of the exits 6a and 9a. Are provided. That is, it is mounted parallel to the vertical plane with respect to the optical axis of the beam from the LD 4a.

The hologram plates 28a and 29a transmit the transmitted light to the LD 4a.
The function is set so that it is transmitted in the direction of the beam emitted from and the reflected light is reflected in the direction of a predetermined angle with respect to the optical axis of the beam.

With this structure, the beam radiated from the LD 4a passes through the hologram plate 18A at the exit 6a and exits, and then passes through the hologram plate 29a at the entrance 9a to enter. The reflected light reflected by 29a does not enter the optical axis of the beam.

In this way, it is possible to prevent the reflected light from entering the direction of the LD 4a again as stray light, the focal position of the servo signal is deviated and blurred due to the stray light, or the stray light returns to the LD 4a and is emitted from the LD 4a. It is possible to prevent the deterioration of the signal quality due to the change of the light quantity of the beam and the disturbance of the light quantity distribution, and it is possible to ensure the recording and reproducing performance.

In the above example, when the cover glass plates 18a and 19a are provided on both the exit port 6a and the entrance port 9a in an inclined manner,
The case where the hologram plates 28a and 29a are provided has been described.
It may be provided on only one of the exit port 6a and the entrance port 9a, and the adverse effect of stray light can be reduced.

[0034]

As described above, according to the present invention, in claim 1, the fixed part for emitting the beam from the light source and the movable part for receiving the beam emitted from the fixed part and irradiating the beam to the outside are provided. A device comprising a light-transmissive material,
At least a first cover plate and a second cover plate, each of which is formed to have a size that closes the exit port of the fixed part from which the beam exits and the entrance port of the movable part to which the beam enters, are provided. By inclining at least one of the two cover plates at a predetermined angle to a plane perpendicular to the optical axis of the beam, the reflected light of either the first cover plate or the second cover plate has a predetermined angle. Since it proceeds in the direction, with a simple configuration,
The focus position of the servo signal is misaligned due to stray light
It is possible to prevent the stray light from returning to the light source and changing the light quantity of the beam emitted from the light source and disturbing the light quantity distribution to deteriorate the signal quality, and it is possible to ensure recording and reproducing performance.

According to a second aspect of the present invention, at least one of the first cover plate and the second cover plate is tilted downward with respect to the outside by a predetermined angle with respect to a plane perpendicular to the optical axis.
Since dust is less likely to adhere and the dust is less likely to adhere, it is possible to prevent attenuation of the light amount due to dust and ensure recording and reproducing performance.

According to a third aspect of the present invention, at least one of the first cover plate and the second cover plate is composed of a hologram plate, the transmitted light of the hologram plate is transmitted in the direction of the beam emitted from the light source, and the reflected light is By setting the beam so that the beam is reflected at a predetermined angle with respect to the optical axis, the mounting method is simple and the recording and reproducing performance can be secured as in the case of the first aspect. There is an effect.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a side view showing the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of the first embodiment.

FIG. 4 is a side view showing a second embodiment of the present invention.

FIG. 5 is a perspective view showing an optical disk device to which the present invention is applied.

FIG. 6 is a side view showing the outline of the optical head.

FIG. 7 is a control block diagram of the optical head.

FIG. 8 is an explanatory diagram of problems in the conventional example.

[Explanation of symbols]

2,2a is a fixed part, 3,3a is a movable part, 4 is a light source, 4a is an LD, 6,6a is an emission port,
9, 9a is an entrance, 18 is a first cover plate, 18a, 19a is a cover glass plate, 19 is a second cover plate, 28 is a third cover plate, 28a, 29a is a hologram plate, and 29 is a fourth plate. Cover plate,

Claims (3)

[Claims] 1. A fixed part (2) for emitting a beam from a light source (4) provided inside, and a movable part for receiving the beam emitted from the fixed part (2) and irradiating the beam to the outside. (3) A beam irradiating device comprising: a light-transmissive material, wherein the beam of the fixed part (2) from which the beam is emitted and the beam of the movable part (3) are incident. The first, each of which is sized to block the entrance (9)
A cover plate (18) and a second cover plate (19) are provided, and at least one of the first cover plate (18) and the second cover plate (19) is perpendicular to the optical axis of the beam. A beam irradiation device characterized by being inclined at a predetermined angle with respect to a surface. 2. The beam irradiation apparatus according to claim 1, wherein at least one of the first cover plate (18) and the second cover plate (19) is inclined downward with respect to the outside. 3. A fixed part (2) for emitting a beam from a light source (4) provided inside, and a movable part for receiving the beam emitted from the fixed part (2) and irradiating the beam to the outside. (3) A device consisting of (3), which is made of a material having a light-transmitting property, and which is an entrance through which the beam of the fixed part (2) is emitted and the beam of the movable part (3) is incident. 3rd, each formed to block the mouth (9)
A cover plate (28) and a fourth cover plate (29) are provided, and at least one of the third cover plate (28) and the fourth cover plate (29) is formed by a hologram, and the hologram is A beam irradiation device, characterized in that transmitted light of a beam is transmitted along an optical axis and reflected light is reflected at a predetermined angle with respect to the optical axis.