JPH05189789A - Lens position sensor of objective lens actuator - Google Patents

Abstract

PURPOSE:To obtain the simple position sensor having high accuracy by providing a slit of a specific length in a focusing direction on the light shielding plate of the lens position sensor and detecting the position in a tracking direction by the light past this slit. CONSTITUTION:A reference plane 23b and the slit 23a which is in parallel with the reference plane 23b and longer than the sum of the size in the tracking direction F of the light receiving surface 41a of a light receiving element 41 and the movable stroke in the focusing direction F of a bobbin 2 are provided on the light shielding plate 23. The reference plane 23b is mounted on the positioning surface 6a provided on the bobbin 2 in parallel with the optical axis of an objective lens 1 and the position in the tracking direction of the bobbin 2 is detected by the exit light form a light emitting element past the slit 23a. The exit light past the slit 23a falls over the entire part of the focusing direction of the light receiving surface 41a and, therefore, the mis-registration of the detection is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in an objective lens actuator for driving an objective lens that focuses a light beam on an optical recording medium for recording and reproducing information, and a lens for detecting the position of the objective lens. It relates to a position sensor.

[0002]

2. Description of the Related Art Conventionally, in an optical pickup device for recording / reproducing information on / from an optical recording medium such as an optical disc or a magneto-optical disc, an objective for irradiating the optical recording medium with a light beam emitted from a light source. A lens and an objective lens actuator for driving the objective lens with respect to the optical recording medium in the focusing direction and the tracking direction are provided.

In the optical pickup device, during the access operation for moving the objective lens actuator including the objective lens to a predetermined position of the optical recording medium, unnecessary vibration occurs in the tracking direction due to the inertia of the objective lens, which affects the access operation. There is a problem of giving.
Therefore, an optical sensor for detecting the position of the objective lens is provided so that an accurate and speedy access operation can be performed based on the detection signal.

Since the detection sensitivity and accuracy of the optical sensor affect the access operation, it is desired to have high sensitivity and accuracy. Japanese Unexamined Patent Publication No. 2-42635 discloses a method of rotationally adjusting a light receiving element so that a detection signal of an optical sensor does not change with respect to movement in a focusing direction. A configuration is shown in which a cylindrical lens is provided in the movable portion of the actuator, and a light source and a light receiving element are provided in the fixed portion to increase the detection sensitivity of the optical sensor.

[0005]

In the above-mentioned prior art, the method disclosed in Japanese Patent Laid-Open No. 2-42635 requires a complicated mechanism for adjusting the rotation of the light-receiving element, which is not practical and is realized. Even if it is possible, there is a problem that the cost will be high. In the configuration of Japanese Patent Laid-Open No. 2-154330, there is a problem that if the light source and the light receiving element are misaligned, the detection range is narrowed, the detection sensitivity is lowered, and the sensitivity varies greatly. There is also a problem in that the screw used to fix the sensor unit may affect the setting and installation of the optical path and other members depending on the position, thus increasing the size of the entire apparatus.

An object of the present invention is to provide a lens position sensor for an objective lens actuator which has a simple and compact structure and is capable of highly sensitive and highly accurate detection.

[0007]

In order to achieve the above object, an objective lens for converging a light beam on an optical recording medium for recording and reproducing information, a movable body equipped with the objective lens, and a movable body are provided. Supporting means for movably supporting the fixed body in the focusing direction and the tracking direction, driving means for driving the movable body in the focusing direction and the tracking direction, a light emitting element provided on the fixed body, and a movable body. A light-shielding plate that allows a part of the light emitted from the light-emitting element to pass therethrough, and a light-receiving element that is provided on the fixed body and that receives the light emitted from the light-emitting element that has passed through the light-shielding plate to detect the tracking direction position of the movable body. In the lens position sensor of the objective lens actuator, the first means of the present invention is characterized in that the light shielding plate is provided with a reference surface and a focus of a light receiving surface of the light receiving element parallel to the reference surface. A slit that is longer than the sum of the dimension in the moving direction and the movable stroke of the movable body in the focusing direction, and the reference surface is attached to the positioning surface provided on the movable body parallel to the optical axis of the objective lens, and the slit is formed. It is characterized in that the position of the movable body in the tracking direction is detected by the light emitted from the light emitting element that has passed through.

A second means is the lens position sensor of the above-mentioned objective lens actuator, wherein a holding body for holding the light receiving element is provided with a guide surface parallel to the light receiving surface of the light receiving element, and the light emitting element is arranged along the guide surface. Adjust the detection output of the light receiving element to the reference value and fix it to the holding body by sliding it in the detection direction of the light receiving element, then slide the holding body in the tracking direction on the fixed body so that the movable body moves in the tracking direction. It is characterized in that the detection output of the light receiving element is adjusted and fixed so as to be a reference value when it is in the neutral position.

A third means is the above-mentioned second means, wherein two guide pins arranged in the tracking direction are provided on the fixed body, and a guide groove into which the two guide pins are slidably fitted is provided. It is characterized in that the holder is provided in parallel with the detection direction of the light receiving element.

The fourth means is the above-mentioned second means or third means, wherein the longitudinal direction is tracked to a part of the fixed body which is on the outer peripheral side of the optical recording medium with respect to the objective lens and which does not block the optical path of the light beam. The through-hole is provided in parallel with the direction, and the holding body is fixed by a screw through the through-hole from the lower surface of the fixed body.

[0011]

According to the above first means, the light shielding plate of the sensor is provided with the reference surface and the sum of the dimension of the light receiving surface of the light receiving element parallel to the reference surface in the focusing direction and the movable stroke of the movable body in the focusing direction. Also, a long slit is provided, a reference surface is attached to the positioning surface provided on the movable body in parallel with the optical axis of the objective lens, and the position of the movable body in the tracking direction is detected by the light emitted from the light emitting element that has passed through the slit. The light passing through the slit always strikes the entire light-receiving surface in the focusing direction, and even if the light-receiving element is tilted, the detection position does not shift when the bobbin moves in the focusing direction.

According to the second means, the holding body for holding the light receiving element is provided with the guide surface parallel to the light receiving surface of the light receiving element, and the light emitting element is slid along the guide surface in the detection direction of the light receiving element. After adjusting the detection output of the light receiving element to the reference value and fixing it to the holding body, slide the holding body in the tracking direction on the fixed body to detect the light receiving element when the movable body is in the neutral position in the tracking direction. Since the output is adjusted and fixed so as to be the reference value, the detectable range is widened, the detection sensitivity is high, and the variation is small.

According to the third means, the two guide pins arranged in the tracking direction on the fixed body are loosely fitted in the guide grooves of the holding body so that the direction parallel to the detection direction of the light receiving element in the holding body. Can be adjusted easily and inexpensively.

Further, according to the fourth means, the screw for fixing the holding body of the sensor to the fixed body can be installed from the lower surface of the fixed body which does not interfere with the luminous flux or other members, so that escape for screw installation etc. Need not be taken into consideration, and downsizing of the entire device in the focusing direction can be achieved.

[0015]

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

FIG. 1 is an exploded perspective view showing an embodiment of an objective lens actuator unit of the present invention, FIG. 2 is a perspective view in which an objective lens mounting portion is partially sectioned, and FIG. 3 is a state when the objective lens of FIG. 2 is mounted. FIG. 4 is a perspective view of the adhesive portion of FIG.

In FIG. 1, a bobbin 2 which is a movable body carrying an objective lens 1 has a focusing coil 3 on a bobbin 2.
Is wound, and the coils 4 for tracking are bonded and fixed on both sides. Further, the bobbin 2 is supported at four positions in the vertical and horizontal directions by a leaf spring 5 which is an elastic supporting means that is deformable in both the focusing direction and the tracking direction.
By controlling the currents flowing through the focusing and tracking coils 3 and 4 that constitute the driving means, the driving is controlled in the focusing direction and the tracking direction by the electromagnetic action of the magnetic circuit with the constant magnetic field.

On the bobbin 2, an objective lens mounting surface 6 on which the objective lens 1 is mounted for positioning in the optical axis direction,
An objective lens fitting portion 7 for positioning the outer diameter of the objective lens 1 and a cylindrical aperture 8 for determining the diameter of the light beam incident on the objective lens 1 are formed at a position one step lower than the objective lens mounting surface 6. There is. Therefore, the light flux transmitting surface of the objective lens 1 does not come into contact with the bobbin 2, and it is possible to prevent the objective lens 1 from being damaged when the objective lens 1 is accidentally tilted and placed during assembly. The cylindrical surface of the aperture 8 is provided with a draft at the time of injection molding so that the diameter on the objective lens side is increased, and the minimum diameter portion on the opposite side to the objective lens 1 is the aperture diameter.
As a result, since the objective lens fitting portion 7 and the aperture 8 can be molded by an integral mold, the coaxiality of the objective lens 1 and the aperture 8 can be realized with high accuracy, and the occurrence of aberration can be suppressed to obtain a more ideal light spot. It can be formed on a recording surface of an optical disc (not shown). Further, by providing the chamfer 9 on the objective lens side of the aperture 8, the distance between the minimum diameter portion of the aperture 8 and the objective lens 1 can be shortened and the diffraction generated at the edge of the minimum diameter portion of the aperture 8 can be minimized.

The objective lens 1 is attached to the objective lens fitting portion 7.
Notches 10 on both sides in the tracking direction so that
By providing the adhesive 11 in the recess formed by the notch 10 and the side surface of the objective lens 1, the adhesive 11 is surely prevented from flowing into the upper surface or the lower surface of the objective lens 1. The objective lens 1 can be fixed to the bobbin 2. The cutouts 10 may be provided at two positions at positions rotated by 90 ° around the optical axis from the positions illustrated in the present embodiment, or at three or more positions. Further, an objective lens balancer B is provided below the bobbin 2 to balance the objective lens 1. The bobbin 2 is made of high strength material such as fiber reinforced plastic or liquid crystal polymer,
This prevents unnecessary resonance when driving the objective lens.

FIG. 5 is an exploded perspective view of the leaf spring mounting portion, and FIG.
7A and 7B are explanatory views of a method of fixing one end of the leaf spring, FIG.
(a), (b) is explanatory drawing of the fixing method of the other end of the leaf spring,
The leaf spring 5, which is an elastic support member that supports the bobbin 2, is made up of two leaf materials having a thickness of several tens of microns, and the deformable portion 5a has a width of several times the thickness and is provided in both the focusing direction and the tracking direction. Deform. The pair of deformable portions 5a are connected by the fixed portion side adhesive portion 5b. Top 2 and bottom 2 4
The deformable portion 5a of the book is arranged in parallel, and supports the bobbin 2 so as to be movable in parallel in the focusing direction and the tracking direction. The fixed side adhesive portion 5b and the movable portion side adhesive portion are provided at both ends of the deformable portion 5a. A protrusion 5d is projected from 5c, and a damping member 15 having a width wider than that of the deformed portion 5a is attached. The damping member 15 is made of a viscoelastic material such as butyl rubber and acts to suppress the amplitude of resonance caused by the leaf spring 5.

The leaf spring support portion 16 of the bobbin 2 is formed with a hole into which the leaf spring fixing pin 17 is inserted, and the movable portion side adhesive portion 5c is formed.
Are sandwiched between the leaf spring fixing pins 17 and fixed by adhesion. Adhesive surface 18 of leaf spring fixing member 18 installed on one side of bobbin 2
a and the fixing portion side adhesive portion 5b of the leaf spring 15 are formed by the leaf spring fixing bar 19
Has a round hole 18b and an elongated hole 18c at positions corresponding to the two pins 19a provided on the plate spring, and the plate spring fixing bar 19 is used for positioning so that the fixing portion side adhesive portion 5b of the plate spring 5 is sandwiched and fixed. To do. After the adhesive fixing, the connecting portion 5e protruding from the fixed portion side adhesive portion 5b is cut at the two-dot chain line portion in FIG.

Since the upper and lower two deforming portions 5a are each made of one leaf spring, they can be assembled easily and accurately. The leaf spring fixing pin 17 and the leaf spring fixing bar 19 are upper and lower common parts, and the leaf spring 5 is also common to the upper and lower sides. Further, the leaf spring fixing member 18 and the leaf spring fixing bar 19 are made of a non-conductive material. , Made of plastic, for example.

As for the method of fixing the leaf spring 5, as shown in FIGS. 6 and 7, the leaf spring support portion 16 of the bobbin 2 and the leaf spring fixing member 18 are provided.
Pins 20a and 20b are formed on the adhesive surfaces 16a and 18a, and the heads of the pins 20a and 20b are crushed and fixed by heat crimping or ultrasonic welding through the pins 20a and 20b in the holes 5f and 5g of the leaf spring 5. You may.

The terminals of the focusing and tracking coils 3 and 4 are bonded to the movable portion 5c of the leaf spring 5.
To the fixed part side adhesive part 5b of the leaf spring 5
Is soldered to the actuator side land portion of the actuator flexible cable 21. The actuator flexible cable 21 is attached with a double-sided tape or the like so as to wind the leaf spring fixing member 18, and at that time, the leaf spring fixing member is used.
Since the step 18d is provided at the position 18, the actuator flexible cable 21 can be positioned and at the same time the actuator flexible cable 21 can be prevented from coming into contact with the wall surface of the carriage base 22.
The land portion on the carriage side is a flexible cable 21 for the actuator attached to the carriage base 22.
Connected to the land part of. Since the connecting portion 5e of the leaf spring 5 is cut, it is possible to independently feed power to the focusing and tracking coils 3 and 4.

As shown in FIG. 5, the bobbin 5 has a light blocking plate 23 for a lens position sensor, which will be described later, and the light blocking plate 23.
A light-shielding plate balancer 24 is provided for balancing. The light-shielding plate 23 and the light-shielding plate balancer 24 are sandwiched and contacted by the upper and lower leaf spring support portions 16, respectively, to reinforce the leaf spring support portion 16 and prevent unnecessary resonance when the objective lens is driven.

FIG. 8 is a perspective view in which a part of the actuator base is cut away, and FIG. 9 is a cross-sectional view of a supporting mechanism portion of the bobbin and the carriage base. The actuator base 25, which is a fixed body, has an inner yoke 26. And an outer yoke 27 are integrally provided, and a permanent magnet 28 is bonded to the outer yoke 27,
Further, a round hole and an elongated hole are bored in the lower surface of the leaf spring fixing member 18, and the leaf spring fixing member 18 is positioned by fitting with a positioning pin 29 provided on the actuator base 25, as shown in FIG. It is fixed with the screw N1 shown. Also upper yoke
30 is attached so as to connect the upper ends of the inner yoke 26 and the outer yoke 27, and the upper yoke 30, the inner yoke 26, the outer yoke 27, the actuator base 25, and the permanent magnet 28 form a magnetic circuit.

8 and 9, the lower surface of the actuator base 25 is provided with a spherical seat 31 which is a part of a spherical surface centered on the principal point X of the objective lens 1. The spherical seat 31 is attached to the carriage base 22. The actuator base 25 is placed on the carriage base 22 so as to come into contact with the annular seat 32 provided. The spherical seat 31 on the side where a light beam enters the triangular prism 33 mounted on the carriage base 22 from a fixed optical system (not shown) is notched, and the spherical seat 31 does not block the incident light.

The actuator base 25 is fixed at the screw hole 25a from the back of the carriage base 22 by two adjusting screws 35 and an urging screw 37 urged by an urging spring 36.
The tilt is adjusted by the two adjusting screws 35 so that the optical axis of the objective lens 1 and the disk surface are vertical. Since the center of the spherical seat 31 coincides with the principal point X of the objective lens 1, the optical axis does not shift even if the actuator base 25 is tilted.
As shown in FIG. 1, of the three through holes 22a to 22c formed in the carriage base 22 for passing the two adjusting screws 35 and the one biasing screw 37, two of the through holes 22a and 22b are The single hole 22c is a long hole having a width substantially equal to the outer diameter of the biasing screw 37, so that the objective lens actuator does not rotate around the optical axis. Further, when adjusting the inclination, the biasing screw 37 has to move in the radial direction of the annular seat 32, so the length direction of the elongated hole 22c is made to coincide with the radial direction of the annular seat 32.

FIG. 10 is an exploded perspective view of the lens position sensor S,
11 is a perspective view showing the bottom surface of the housing of FIG. 10, FIG. 12 is a perspective view for explaining the attachment of the light shielding plate, FIG. 13 is a partial cross-sectional view for explaining the attachment of the light shielding plate, and FIG. ) And (b) are explanatory views of the detection sensitivity of the lens position sensor. The light shielding plate 23 attached to the bobbin 2 is provided with a slit 23a long in the focusing direction, and the slits 23a from the light emitting element 40 are provided. The light that passes through is 2 in the tracking direction.
It is incident on the light receiving element 41 having the divided light receiving surface 41a. The slit 23a is longer than the sum of the dimension of the light receiving surface 41a in the focusing direction F and the movable stroke of the bobbin 2 in the focusing direction F.

In this embodiment, a light emitting diode is used as the light emitting element 40 and a Fort diode is used as the light receiving element 41. The light receiving element 41 outputs an electric signal according to the amount of received light,
The positions of the bobbin 2 and the objective lens 1 in the tracking direction can be detected by the difference between the outputs of the left and right light receiving surfaces 41a. As shown in FIGS. 12 and 13, the light shielding plate 23 is provided with a positioning surface 6a formed perpendicularly to the objective lens mounting surface 6 of the bobbin 2.
The reference surface 23b is attached to and is slit parallel to the reference surface 23b.
Since 23a is formed, the parallelism between the optical axis of the objective lens 1 and the slit 23a is maintained with high accuracy. The length of the slit 23a in the focusing direction F is determined by the light receiving element 41.
Since the dimension of the light receiving surface 41a in the focusing direction is longer than the sum of the movable stroke of the bobbin 2 in the focusing direction, the light passing through the slit 23a always strikes the entire light receiving surface 41a in the focusing direction, and the light receiving element 41a. Even if is tilted, the detection position does not shift when the bobbin 2 moves in the focusing direction.

The position signal thus detected represents the relative displacement between the objective lens 1 and the light receiving element 41 = carriage base 22 = triangular prism 33, so that the carriage base ( = Light receiving element 41 = By moving the triangular prism 33) 22, the luminous flux that always enters the objective lens 1 from the triangular prism 33 and the objective lens 1
The optical axis of can be made to match. The above lens position detector is on the outer circumference of the actuator base 25 disk.
It is provided on the (fixed optical system side) so that the lens position sensor S and the spindle motor (not shown) can be prevented from interfering with each other, so that the accessible range on the inner circumference side of the disk is widened.

When assembling the above lens position detecting portion, first, the guide plate 45 attached to the light emitting element 40 is used.
Is a light receiving element 41 provided in a housing 46 that is a holding body.
Slide the light emitting element 40 so as to contact the guide surface 46a parallel to the light receiving surface 41a, so that the light receiving amounts of the left and right light receiving surfaces 41a become equal (so that the difference between the outputs of the left and right light receiving surfaces becomes zero. ) Adjust and fix. Actuator base 25
As shown in FIG. 8, the two guide pins 47 arranged side by side in the tracking direction and the light receiving surface on the lower surface of the housing 46.
The housing 4 is provided by the guide groove 48 provided in parallel with 41a.
6 is guided in the tracking direction, and the housing 46
Slide so that when the objective lens 1 is at the neutral position in the tracking direction, the amount of light passing through the slit 23a of the light shielding plate 23 becomes equal on the left and right light receiving surfaces 41a (the difference between the outputs of the left and right light receiving surfaces). Is adjusted so that it becomes zero), and as shown in FIG. The position of the screw N2 is shifted so as not to block the light beam from the pickup unit.

By the way, as shown in FIG. 14 (a), generally, the light amount distribution of most light emitting elements is strong in the central part and weakens toward the peripheral part. When the light emitting elements are adjusted, the light amount distributions Fh incident on the light receiving surfaces A and B become equal to each other on the left and right, and when the center of the slit SL and the dividing line C coincide with each other, the output difference between the left and right light receiving surfaces A and B is zero. Becomes As shown in FIG. 14 (b), when the slit SL of the light shielding plate (= objective lens) is moved to the right (or left) by a '(b'), all the light is incident on the light receiving surface A (or B). The position cannot be detected any further.
That is, the detectable range is a ', b'. If the light receiving distribution Fh 'of the light emitting element is deviated, the difference between the outputs of the left and right light receiving surfaces becomes zero at the position where the center of the slit SL deviates from the dividing line. At this time, the detectable range becomes uneven on the left and right, and the detectable range on one side becomes narrow. Further, when the center of the light amount distribution and the dividing line C are coincident with each other, the amount of received light is large, so that the detection sensitivity is high, and since the light amount distribution is flat, variations in sensitivity are small. Therefore, it is necessary to adjust the amount of received light.

Further, as shown in FIG.
Power is supplied to the light receiving element 41 through the lens position sensor flexible cable 50 shown in FIG. The lens position sensor flexible cable 50 is attached by a double-sided tape or the like so as to wind the housing 46, and the carriage side land portion is connected to the land portion of the actuator flexible cable 21 attached to the leaf spring fixing member 18.

[0035]

As described above, according to the first means of the present invention, the light for detection can be always applied to the entire focusing direction of the light receiving surface, and the bobbin moves in the focusing direction even if the light receiving element is tilted. In this case, the detection position can be prevented from being displaced when it is performed, and according to the second means, the light receiving element and the light emitting element can be installed and adjusted so that the detectable range is widened, the detection sensitivity is high, and the variation is small. According to the third means, the guide for adjusting the installation of the light receiving element and the light emitting element can be reliably, easily, and inexpensively manufactured with a simple structure including the two guide pins and the guide groove. According to the means, it is possible to prevent the detection light and other members from being affected even by fixing the screw, and it is not necessary to consider the escape for installing the screw. Small It is possible to achieve, in a simple and compact can be achieved configurations can provide high sensitivity, a lens position sensor of the objective lens actuator that can highly accurate detection.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of an objective lens actuator of the present invention.

FIG. 2 is a perspective view in which an objective lens mounting portion is partially sectioned.

FIG. 3 is a sectional view showing a state where the objective lens of FIG. 2 is attached.

FIG. 4 is a perspective view of an adhesive portion of FIG.

FIG. 5 is an exploded perspective view of a leaf spring mounting portion.

FIG. 6 is an explanatory diagram of a method of fixing one end of a leaf spring.

FIG. 7 is an explanatory diagram of a method of fixing the other end of the leaf spring.

FIG. 8 is a perspective view showing a part of the actuator base by cutting.

FIG. 9 is a sectional view of a supporting mechanism portion for a bobbin and a carriage base.

FIG. 10 is an exploded perspective view of a lens position sensor.

11 is a perspective view showing a bottom surface of the housing of FIG.

FIG. 12 is a perspective view for explaining attachment of a light shielding plate.

FIG. 13 is a partial cross-sectional view for explaining attachment of a light shielding plate.

FIG. 14 is an explanatory diagram of detection sensitivity of a lens position sensor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Objective lens, 2 ... Bobbin (movable body), 3, 4 ... Coil (driving means), 5 ... Leaf spring (supporting means), 6a ... Positioning surface, 23 ... Shading plate, 23a, SL ... Slit, 2
3b… Reference plane, 25… Actuator base (fixed body),
40 ... Light emitting element, 41 ... Light receiving element, 41a ... Light receiving surface, 45
… Guide plate, 46… Housing (holding body), 46a
… Guide surface, 47… Guide pin, 48… Guide groove.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hideaki Kibune 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (4)

[Claims] 1. An objective lens for condensing a light beam on an optical recording medium for recording and reproducing information, a movable body equipped with the objective lens, and the movable body moved in a focusing direction and a tracking direction with respect to a fixed body. Support means for supporting possible,
Driving means for driving the movable body in the focusing direction and the tracking direction, a light emitting element provided on the fixed body, a light shielding plate provided on the movable body for passing a part of light emitted from the light emitting element, and the fixed body. In the lens position sensor of the objective lens actuator, which is provided with a light-receiving element that receives light emitted from the light-emitting element that has passed through the light-shielding plate and detects the position of the movable body in the tracking direction,
A reference surface, and a slit that is parallel to the reference surface and is longer than the sum of the dimension of the light receiving surface of the light receiving element in the focusing direction and the movable stroke of the movable body in the focusing direction,
The reference surface is attached to a positioning surface provided on the movable body in parallel with the optical axis of the objective lens, and the tracking direction position of the movable body is detected by the light emitted from the light emitting element that has passed through the slit. A lens position sensor for an objective lens actuator. 2. An objective lens for condensing a light beam on an optical recording medium for recording and reproducing information, a movable body having the objective lens mounted thereon, and the movable body is moved in a focusing direction and a tracking direction with respect to a fixed body. Support means for supporting possible,
Driving means for driving the movable body in the focusing direction and the tracking direction, a light emitting element provided on the fixed body, a light shielding plate provided on the movable body for passing a part of light emitted from the light emitting element, and a fixed body. In a lens position sensor of an objective lens actuator, which is provided with a light receiving element that receives light emitted from a light emitting element that has passed through a light shielding plate and detects the tracking direction position of a movable body, a holding body that holds the light receiving element. A guide surface parallel to the light-receiving surface of the light-receiving element is provided, and the light-emitting element is slid along the guide surface in the detection direction of the light-receiving element so that the detection output of the light-receiving element is adjusted to a reference value. When the movable body is in the neutral position in the tracking direction by fixing and sliding the holding body in the tracking direction on the fixed body, the detection output of the light receiving element becomes the reference value. Lens position sensor of the objective lens actuator, characterized in that the fixed and adjusted to. 3. Two guide pins lined up in the tracking direction are provided on the fixed body, and a guide groove in which the two guide pins are slidably fitted is provided in the holding body in parallel with the detection direction of the light receiving element. The lens position sensor of the objective lens actuator according to claim 2, wherein 4. A through-hole is provided on the outer peripheral side of the optical recording medium with respect to the objective lens and in a part of the fixed body that does not block the optical path of the light flux, the longitudinal direction being parallel to the tracking direction, and the lower surface of the fixed body. 4. The lens position sensor for an objective lens actuator according to claim 2, wherein the holding body is fixed by a screw passing through the through hole.