JPH0822627A - Optical information recording and reproducing device - Google Patents

Abstract

PURPOSE:To provide a device whose position detecting precision in the tracking direction is not susceptible to adverse effects caused by stray light originated from the laser light source by disposing a pair of different reflection-type proximity sensors, which compose the position detecting sensor in the tracking direction together with a pair of reflecting planes, at specified positions in the device. CONSTITUTION:The laser light 13 from a fixed optical system is reflected by a deflection mirror in the objective lens holder 50 and used as recording light after passing the objective lens 53. A pair of reflection type proximity sensors 63, 64 which are separated by different reflection distances d1, d2 from the reflection surface 61, 62 and function as a position detecting sensor in the tracking direction T are disposed on the carriage side opposite to the laser light 13 and accordingly the stray light of the laser light 13 is hindered by the holder 50, not causing its incidence on the sensors, 63, 64. Thus, in this type of optical information recording and reproducing device, the stray light from the laser light source has no adverse effect on the precision of position detection in the tracking direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus, and more particularly to a position detecting sensor in an tracking direction of an objective lens holder.

[0002]

2. Description of the Related Art As an optical recording / reproducing device, there is known an optical recording / reproducing device in which an optical system is divided into a movable portion and a fixed portion, and a disc access speed at the time of recording / reproducing is changed.
In such an optical recording / reproducing apparatus, a laser beam is applied to a carriage movable in the radial direction of an optical recording disk from a direction parallel to the moving direction, and the laser light is deflected by a deflection mirror mounted on the carriage. Deflected by
It is incident on the objective lens. The objective lens is supported by an objective lens holder that is supported on a carriage by being movable in a focus direction toward and away from the recording disc and in a radial direction (tracking direction) of the recording disc. An electromagnetic drive circuit provided between the objective lens holders drives minutely in the focus direction and the tracking direction to form a laser spot on the recording portion of the disk.

In this apparatus, the objective lens holder is driven in the tracking direction by the electromagnetic drive circuit based on the track error signal, so that the position of the objective lens holder on the carriage in the tracking direction is detected. Conventionally, this position detector is provided with a pair of reflecting surfaces on the outer surface of the objective lens holder, located on both sides in the tracking direction with respect to the optical axis of the objective lens, and a pair of reflecting surfaces facing the pair of reflecting surfaces on the carriage side. A reflection type proximity sensor is provided. At the neutral position of the objective lens holder, the distance between the pair of sensors and the reflecting surface is the same, and the pair of sensors produce the same output. On the other hand, when displaced from the neutral position, the outputs of the pair of sensors change. Therefore, the position of the objective lens holder on the carriage can be detected by capturing the difference in the output changes.

However, it has become clear that the laser beam from the light source acts as stray light in the position detector in the tracking direction and the position detection accuracy is deteriorated as the carriage is miniaturized. In other words, the stray light of the laser light from the laser light source is incident on the sensor closer to the light source of the pair of reflective sensors, so that accurate position detection cannot be performed even if the outputs of the pair of sensors are compared.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a position detector in which stray light from a laser light source does not adversely affect position detection accuracy in the tracking direction.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to a carriage that is movable in the radial direction of an optical recording disk; a laser light source that gives laser light to the carriage from a direction parallel to the moving direction; An objective lens holder provided so as to be movable in a focus direction away from and in a tracking direction of the recording disc; an objective lens supported by the objective lens holder to focus laser light on the recording disc; and on the carriage of the objective lens holder. In an optical information recording / reproducing apparatus equipped with a position detection sensor for detecting a position in the tracking direction, the position detection sensor in the tracking direction is positioned on the side opposite to the light source with respect to the optical axis of the objective lens, and tracking is performed. A pair that is provided on the outer surface of the objective lens holder by changing the position in the direction orthogonal to the direction. A reflecting surface; for each reflecting surface of the pair of reflecting surfaces, and is separated in the tracking direction the pair of the reflective proximity sensor provided on the carriage side; consist of,
In addition, the pair of reflective sensors are characterized in that they have different output characteristics with respect to the distance from the reflective surface.

Considering the output characteristics of the reflection type sensor obtained at present, the output of the pair of reflection type sensors and the pair of reflection surfaces are opposite to each other when the objective lens holder moves in the tracking direction. Need to be placed.

[0008]

Embodiments of the present invention will be described with reference to the drawings. First, the configuration of the optical information recording / reproducing apparatus according to the embodiment will be described with reference to FIGS. A carriage 20 (FIG. 6) is supported below the rotationally driven optical recording disk 11 so as to be movable in the radial direction R. On the other hand, the laser light 13 emitted from the stationary optical system 12 that does not move is emitted toward the carriage 20 from a direction parallel to the radial direction R.

On the carriage 20, a deflection mirror support 30 and a mount 40 are provided as a fixed object for the carriage 20, and an objective lens holder 50 is provided as a movable object for the carriage 20. The deflecting mirror support base 30 is made of a magnetic material, and as is particularly clear in the disassembled state of FIG. 5, a horizontal substrate 31 and a mirror support cylinder 32 extending upward from a substantially central portion of the horizontal substrate 31.
And a pair of vertical plate portions (yoke portions) 33 extending upward with the mirror support tube 32 interposed therebetween. Horizontal board 3
1 to a plurality of fixing flanges 34 to the carriage 20.
Has been extended.

The mirror support tube 32 is formed in a rectangular tube shape in conformity with the shape of the deflection mirror 35, and the deflection mirror 35 is fixed thereon. A pair of focus magnets 36 are fixed to the vertical plate portion 33 below the vertical plate portion 33 with the mirror support cylinder 32 interposed therebetween, and above the vertical plate portion 33, the deflection mirror 3 is provided above.
A pair of track magnets 37 are fixed with 5 in between. Vertical plate portion 33, horizontal substrate 31, mirror support tube 3
Reference numeral 2 constitutes a magnetic circuit together with the focus magnet 36 and the track magnet 37.

The mount 40, together with the printed circuit board 41, is fixed to the deflection mirror support base 30 by fixing screws 42.
It is fixed to one vertical plate portion 33. Mount 40
One end of each of four suspension wires 43 located on the upper, lower, left and right sides is fixed to the.

The objective lens holder 50 has a cylindrical bobbin 51 substantially in the center thereof, and a pair of the other ends of the four suspension wires 43 are connected in the diameter direction of the cylindrical bobbin 51. The wings 52 are provided. An objective lens 53 is fixed to the upper end of the cylindrical bobbin 51, and the fixed optical system 12 is attached to one of the pair of wings 52.
There is formed an opening 54 for receiving the laser beam 13 from the and guiding it to the deflection mirror 35. Objective lens holder 50
Is movable by a minute distance in the focus direction and the tracking direction due to the elasticity of the suspension wire 43.

The objective lens holder 50 and the deflection mirror support base 30 are composed of a cylindrical bobbin 51 of the objective lens holder 50.
The deflection mirror 35 and the mirror support tube 32 of the deflection mirror support base 30 are inserted therein, and the track magnet 37 and the focus magnet 36 are assembled on the outer surface of the cylindrical bobbin 51. Cylindrical bobbin 51
A track coil 56 is fixed so as to face the pair of track magnets 37, and a focus coil 57 is fixed so as to face the pair of focus magnets 36. These coils and magnets form electromagnetic drive circuits in the track direction and the focus direction, respectively, and the objective lens holder 50 is driven in the track direction and the focus direction depending on the direction and magnitude of the current flowing through the track coil 56 and the focus coil 57. To be done.

The position detecting sensor in the tracking direction which is a feature of the present invention is, for example, in the optical information recording / reproducing apparatus configured as described above, as shown in FIG. 1, the objective lens 53 is provided on the outer surface of the objective lens holder 50. The pair of reflecting surfaces 61 and 62 are provided on the opposite side of the fixed optical system 12 (laser light 13) with respect to the optical axis of the above, and the reflecting surfaces 61 and 62 are fixed to the fixing plate 21 fixed on the carriage 20. And a pair of reflection type proximity sensors 63 and 64 facing each other. The reflective surface 61 and the reflective proximity sensor 63, and the reflective surface 62 and the reflective proximity sensor 64 are provided at different positions in the direction orthogonal to the tracking direction T, and the reflective surface 61 and the reflective proximity sensor are provided. the distance d ₁ of the sensor 63, the reflecting surface 62 a distance d ₂ of the reflection-type proximity sensor 64 different from each other. The reflecting surfaces 61 and 62 and the light receiving surfaces of the reflective proximity sensors 63 and 64 are orthogonal to the tracking direction T.

The reflection type proximity sensors 63 and 64 are respectively
The light emitting element and the light receiving element are incorporated, and the light emitted from the light emitting element and reflected by the reflection surfaces 61 and 62 is received by the light receiving element. The output of the light receiving element changes according to the distance from the reflecting surfaces 61 and 62. In the present invention, the reflective proximity sensors 63 and 64 having different distance characteristics from the reflective surfaces are used. 2 and 3 show examples of output characteristics thereof. The reflection type proximity sensor 63 has a distance of 0.7 m from the reflection surface 61.
While the peak output is generated when the distance is around m, the reflective proximity sensor 64 generates the peak output when the distance from the reflection surface 62 is around 3 mm. Therefore, this reflection type proximity sensor 6
By comparing the outputs of 3 and 64, the position (displacement) of the objective lens holder 50 with respect to the fixed plate 21 on the carriage 20 can be detected.

In the optical recording / reproducing apparatus having the above-mentioned structure, the laser beam 13 emitted from the fixed optical system 12 has the opening 54.
Then, the light enters the cylindrical bobbin 51 of the objective lens holder 50, is reflected by the deflection mirror 35, and reaches the objective lens 53. The objective lens 53 focuses the laser light on the recording surface of the recording disk 11, and forms a recording spot on the recording surface of the recording disk 11 in the case of a recording system. In the case of a reading system, the reflected light from the recording disk 11 follows the optical path opposite to the incident optical path described above to reach the fixed optical system 12, and the recording information recorded on the recording disk 11 by the known reading system. Is read.

Track coil 56, focus coil 5
A control current is given to 7 based on the tracking error signal and the focus error signal, and the objective lens 53
The objective lens holder 50 is arranged so that the laser spot due to is accurately focused on the recording track of the recording disk 11.
Moves.

The outputs of the reflection type proximity sensors 63 and 64 are based on the tracking error signal and the objective lens holder 5
Used when driving 0. In the present invention, since the reflection type proximity sensors 63 and 64 are located on the outer surface of the objective lens holder 50 and located on the opposite side of the fixed optical system 12 with respect to the objective lens 53, the stray light of the laser light 13 is incident. There is no danger of Then, the reflective proximity sensors 63, 6
Since No. 4 has different output characteristics with respect to changes in the distance from the reflecting surfaces 61 and 62, the position of the objective lens holder 50 can be detected reliably. If the reflection type proximity sensors 63 and 64 have the same output characteristics, they cannot be arranged at the optimum positions because they must be arranged close to or far from the reflection plate.

[0019]

According to the optical information recording / reproducing apparatus of the present invention, the stray light from the laser light source does not adversely affect the position detection accuracy in the tracking direction.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of an optical information recording / reproducing apparatus according to the present invention.

FIG. 2 is a graph showing an example of output characteristics of one of the pair of reflective proximity sensors shown in FIG.

FIG. 3 is a graph showing an output characteristic example of the other of the pair of reflective proximity sensors shown in FIG.

FIG. 4 is a partially cutaway perspective view showing an embodiment of an optical information recording / reproducing apparatus according to the present invention.

FIG. 5 is an exploded perspective view of the main part.

6 is a sectional view taken along line VI-VI of FIG.

7 is a sectional view taken along line VII-VII of FIG.

[Explanation of symbols]

 11 Recording Disc 12 Fixed Optical System 13 Laser Light 20 Carriage 35 Deflection Mirror 36 Focus Magnet 37 Track Magnet 43 Suspension Wire 50 Objective Lens Holder 53 Objective Lens 56 Track Coil 57 Focus Coil 61 62 Reflective Surface 63 64 Reflective Proximity Sensor

Claims (2)

[Claims] 1. A carriage movable in a radial direction of an optical recording disk; a laser light source for giving a laser beam to the carriage in a direction parallel to the moving direction; a focus for contacting and separating the recording disk on the carriage. Direction and the tracking direction of the recording disk, the objective lens holder provided so as to be movable; supported by this objective lens holder,
An objective lens that focuses the laser light on a recording disk;
And an optical information recording / reproducing apparatus including a position detecting sensor for detecting a position of the objective lens holder on a carriage in a tracking direction, wherein the position detecting sensor is opposite to the light source with respect to an optical axis of the objective lens. And a pair of reflecting surfaces provided on the outer surface of the objective lens holder with different positions in the direction orthogonal to the tracking direction; and with respect to each reflecting surface of the pair of reflecting surfaces in the tracking direction. A pair of reflective proximity sensors that are spaced apart from each other and provided on the carriage side; and the pair of reflective sensors have different output characteristics with respect to the distance from the reflective surface. Optical information recording / reproducing device. 2. The optical information recording / reproducing apparatus according to claim 1, wherein the pair of reflective sensors and the pair of reflective surfaces are arranged such that their distances in the tracking direction are different from each other.