JPH0521331U - Optical information recording / reproducing device - Google Patents

Abstract

(57) [Summary] [Object] To prevent erroneous detection due to light leakage from an optical disc in a reflective photosensor used for radial control of an optical disc device. [Structure] A light emitting section 21 is provided on a side surface of an objective lens structure (objective lens 5 and lens holder 14) facing an optical disk.
A reflection type photo sensor 20 in which a light receiving section 22 and a light receiving section 22 are integrally provided.
Are arranged so as to face each other, the light from the light emitting portion reflected by the side surface of the objective lens structure is detected by the light receiving portion to detect the position of the objective lens structure, and the photo sensor allocates the light emitting portion to the optical disc 1 side. The light receiving portion is provided on the side away from the optical disc so that the light leaked from the optical disc does not reach the light receiving portion of the photosensor and affect the detection output.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an optical information recording / reproducing apparatus (hereinafter, referred to as an optical disk apparatus) for reproducing information or recording / reproducing information on / from an optical disk such as a magneto-optical disk, and particularly to information recording provided in the circumferential direction of the optical disk. The present invention relates to the structure of an optical head that moves in a direction intersecting a track to write and read information.

[0002]

[Prior Art]

 Generally, in an optical disc device, an objective lens that forms an image of light emitted from a laser light source on the optical disc surface or detects reflected light from the optical disc surface in order to write or read information to or from the optical disc. An optical head having is provided. Usually, this optical head performs focusing control for focusing on the optical disc and tracking control for aligning the objective lens with the track of the optical disc. Further, in an optical disk device that requires high-speed access to information, it is necessary to detect the positional displacement of the objective lens in the radial direction (radial direction) of the optical disk, and a photosensor is conventionally used as a detector for this purpose. There are many things.

For example, a pair of reflection-type photosensors in which a light-emitting element and a light-receiving element are integrally formed are arranged so as to face each other on both side surfaces (both side surfaces in the radial direction) of a lens holder holding the objective lens. It has been proposed that the position of the objective lens is detected by using the output difference of each photosensor due to the displacement in the track direction, and the radial control is performed based on the detection result.

[0004]

[Problems to be solved by the device]

 However, in such a conventional structure for radial control, it is necessary to dispose the photosensor in a position close to the objective lens, so that the light reflected by the optical disk easily leaks into the photosensor. There is a problem in that the photo sensor incorrectly detects the light, and accurate radial control is not performed. An object of the present invention is to provide an optical disk device which prevents erroneous detection in a photo sensor and enables accurate tracking control.

[0005]

[Means for Solving the Problems]

 In the optical disk device of the present invention, the light emitting portion of the photosensor, which is arranged opposite to the side surface of the objective lens structure facing the optical disk, is arranged on the optical disk side, and the light receiving portion is arranged on the side remote from the optical disk.

[0006]

【Example】

 Next, the present invention will be described with reference to the drawings. FIG. 5 is a schematic perspective view of an optical head of an optical disk device according to the present invention. In FIG. 5, reference numeral 2 denotes a pair of rails extending in the radial direction of the optical disk 1, along which the carriage 3 moves. Configured to be possible. A prism 4 as a reflecting mirror having a reflecting surface inclined at 45 ° is supported on the carriage 3, and light from a fixed optical system 6 incident along the rail 2 is provided on the upper surface of the carriage. Reflected vertically above the carriage through a window not shown. Further, a fine adjustment actuator 7 as an objective lens structure for supporting an objective lens 5 for forming an image of the light reflected by the prism 4 on the optical disc 1 is provided above the carriage 3.

This fine adjustment actuator 7 is shown in a schematic perspective view in FIG. 1, a plan view in FIG. 2, a front view in FIG. 3, and a left side view in FIG. It has a yoke structure composed of an outer yoke 11 having a U-shape facing upward and two inner yokes 12 provided upright between the outer yokes 11. The yoke structure is fixed to the upper surface of the carriage 3. There is. A window (not shown) for allowing the light reflected by the prism 4 to pass therethrough is opened on the bottom surface of this yoke structure, and a magnet 11 supported on the inner surface of each side piece of the outer yoke 11 serves to form the inner yoke 12. Form a magnetic field between them. The lens holder 14 is arranged in this magnetic field. A focus drive coil 17 is wound in the horizontal direction on the side surface of the lens holder 14, and radial drive coils 18 are wound in the vertical direction on both sides in the left-right direction.

In addition, the lens holder 14 is provided with an opening for passing light through which the light reflected by the reflecting mirror passes at the central position of the upper surface, and the objective lens 5 is attached to the inner edge of the upper side of this opening. It is fixed with a drug. Further, a pair of suspension wires 15 are connected to both ends of the lens holder 14, respectively, so that the lens holder 14 is supported in a cantilever state by a support wall 16 erected on the carriage 3. The suspension wire 15 can be deformed in the up-down direction and the left-right direction (radial direction of the optical disk, the same applies below) with the support end of the support wall 16 as a fulcrum, and the force received by the electromagnetic action causes the lens holder 14 to move in the vertical direction and It is supported so that it can move in parallel in the left and right directions.

Further, reflecting plates 19 are attached to the left and right side surfaces of the lens holder 14, and reflective photosensors 20 are arranged to face the reflecting plates 19, and the photosensors 20 are not shown in the drawing. It is supported by the yoke structure via a sensor holder. As shown in the front view of FIG. 6, each of the reflection type photosensors 20 is configured as an element in which a light emitting section 21 and a light receiving section 22 are integrally arranged, and the reflection plate 19 is emitted by the light emitting section 21. The light reflected by is detected by the light receiving section 22. As shown in FIG. 7, the electric signal output from the light receiving section 22 has a characteristic in which the collector current changes as the distance between the photo sensor and the reflection plate changes.

As shown in FIG. 8, the pair of photosensors 20 has a circuit configuration in which each light emitting section 21 is connected to a power source and each light receiving section 22 is connected to the positive and negative input terminals of the differential amplifier 23, respectively. The differential output characteristics shown in FIG. 9 can be obtained by obtaining the output difference from each light receiving unit 22 by the differential amplifier 23. Thus, the distance between each photo sensor 20 and the side surface of the lens holder 14 (more precisely, the surface of the reflection plate 19) can be obtained based on the output of the differential amplifier 23, and how much the objective lens 5 is from the normal position. It is possible to detect if it is displaced. In this embodiment, the back slope of the photosensor output characteristic shown in FIG. 7 is used in order to widen the linear area of the photosensor with respect to the displacement of the objective lens. In the case of detection, the front slope of the photo sensor output may be used.

As shown in FIG. 4, the photosensors 20 are installed so that the light emitting portion 21 and the light receiving portion 22 are arranged vertically, and the light emitting portion 21 is located above the optical disc 1 in the upper side. In addition, the light receiving portions 22 are arranged so as to be located on the lower side apart from the optical disc 1. Therefore, the light from the light emitting portion 21 is reflected slightly downward by the reflecting plate 19 and detected by the light receiving portion 22.

According to this configuration, as shown by the arrow in FIG. 4, part of the light projected from the objective lens 5 onto the optical disc 1 and reflected by the optical disc 1 reaches the photosensor 20. However, since the photosensor 20 has the light emitting portion 21 arranged on the optical disc 1 side and the light receiving portion 22 is set at a position separated from the optical disc 1, the light leakage from the optical disc 1 is detected by the light receiving portion. It will never reach 22. As a result, the detection output of the light receiving unit 22 is hardly affected by the leaked light, and the position of the lens holder 14 can be accurately detected and the radial control can be executed with high accuracy.

[0013]

[Effect of the device]

 As described above, according to the present invention, the light emitting portion of the photosensor, which is arranged opposite to the side surface of the objective lens structure facing the optical disc, is arranged on the optical disc side, and the light receiving portion is arranged on the side distant from the optical disc. Therefore, even if light leaks from the optical disk to the photosensor, the light leak is less likely to reach the light receiving section of the photosensor, erroneous detection at the light receiving section can be prevented, and the accurate objective lens structure can be prevented. It is possible to detect the position of, and it is possible to realize highly accurate radial control.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of a fine adjustment actuator of an optical disk device to which the present invention is applied.

FIG. 2 is a plan view of FIG.

FIG. 3 is a front view of FIG.

FIG. 4 is a left side view of a main part of FIG.

FIG. 5 is a schematic perspective view of an optical head to which the present invention is applied.

FIG. 6 is a front view of a reflective photosensor.

FIG. 7 is an output characteristic diagram of a reflective photosensor.

FIG. 8 is a circuit diagram showing electrical connection of a pair of photosensors.

FIG. 9 is a characteristic diagram showing a relationship between a detection output by a pair of photosensors and displacement.

[Explanation of symbols]

 1 Optical Disc 3 Carriage 5 Objective Lens 7 Fine Adjustment Actuator 11 External Yoke 12 Inner Yoke 13 Magnet 14 Lens Holder 17 Focus Drive Coil 18 Radial Drive Coil 19 Reflector 20 Photo Sensor 21 Light Emitting Section 22 Light Receiving Section

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shinpei Shinozaki 2-6-9 Maenocho, Itabashi-ku, Tokyo Asahi Kogaku Kogyo Co., Ltd.

Claims (1)

[Scope of utility model registration request] 1. A reflection type photosensor integrally provided with a light emitting portion and a light receiving portion is arranged opposite to a side surface of an objective lens structure facing the optical disc, and a light emitting portion reflected from the side surface of the objective lens structure is provided. In the optical information recording / reproducing apparatus for detecting the position of the objective lens structure by detecting the light of the above with the light receiving section, the photo sensor has the light emitting section on the optical disk side and the light receiving section on the side away from the optical disk. An optical information recording / reproducing device characterized in that