JPH06259796A - Optical disc tilt detection device and optical pickup device - Google Patents

Abstract

(57) [Summary] [Object] To provide an optical disk tilt detection device for detecting the relative tilt between an optical disk and an objective lens movable part with a simple configuration. [Structure] The first light emitting element 11 emits light toward the optical disc 1, and the first light receiving elements 12 and 13 receive the reflected light. The second light emitting element 14 emits light toward the objective lens movable portion 10, and the second light receiving elements 15 and 16 receive the reflected light. The differential amplifier 18 takes the difference between the outputs of the first and second light receiving elements, detects the inclinations of both the optical disc 1 and the objective lens movable portion 10, and detects the relative inclinations of both. Then, based on the obtained tilt detection signal, only the objective lens moving part 10 is tilted, so that the weight of the moving part can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc tilt detecting device used for a CD player, a video disc, etc., and an optical pickup device using the same.

[0002]

2. Description of the Related Art When an optical disc such as a video disc is played back, the optical disc bends at the outer circumference. Therefore, when the outer circumference of the optical disc is played back, the optical disc and the optical pickup for playing the optical disc are tilted, and the quality of the playback signal is deteriorated. Deteriorates.

In order to prevent the reproduction signal from deteriorating due to the tilt of the optical disk, conventionally, the tilt of the optical disk is detected by a tilt detecting device of the optical disk, and the tilt of the optical pickup is tilted according to the tilt signal thus detected so that the tilt of the optical disk is corrected. The recorded signal is being reproduced.

A first conventional example of an optical disc tilt detection device and an optical pickup will be described with reference to the drawings.

FIG. 10 is a perspective view of such a conventional optical disc tilt detecting device used in a video disc player and an optical pickup device using the same.

In FIG. 10, 1 is an optical disc, 2 is an optical pickup, and the optical pickup 2 is for reproducing information from the optical disc 1. Reference numeral 3 denotes an objective lens, and the optical pickup 2 receives the optical disc 1 via the objective lens 3.
Playing information. If the parallelism between the optical disc 1 and the objective lens 3 is deviated, the information reproduction characteristic of the optical disc 1 is deteriorated.

Reference numeral 4 denotes an optical disc tilt detection device, which is formed on the optical pickup 2 and is arranged along the radial direction of the optical disc 1 based on the tilt signal of the optical disc 1 detected by the optical disc tilt detection device 4 (in the figure). (In the direction of the arrow) to maintain the parallelism between the objective lens 3 and the optical disk 1 by tilting, and configure an optical pickup device that corrects the tilt of the optical disk 1.

The optical disc tilt detecting device 4 is composed of a light emitting element 5 such as an LED and light receiving elements 6 and 7. The light emitted from the light emitting element 5 is applied to the optical disc 1 to receive the light amount distribution of the reflected light. Light is received by the elements 6 and 7 to detect the tilt signal of the optical disk 1.

The control device for controlling the tilt correction of the optical pickup device tilts the optical pickup 2 by tilting the optical pickup 2 by substantially the same amount as the tilt amount of the optical disk 1 based on the signal from the tilt detecting device 4 of the optical disk. Is configured to correct.

FIG. 11 is a detailed side view of the conventional tilt detecting device 4 for an optical disk. In FIG. 11, reference numeral 5 denotes a light emitting element, which emits divergent light toward the optical disk 1. 6,7
Is a light receiving element, and is configured to receive the light emitted from the light emitting element 5 and reflected by the optical disc 1 on both sides of the light emitting element 5.

In FIG. 11, (a) shows a state in which the optical disc 1 is not tilted, and the light emitted from the light emitting element 5 is reflected on the optical disc 1 substantially evenly to the left and right to receive the light receiving elements 6, 7.
Incident on. At this time, the light amounts detected by the light receiving elements 6 and 7 are almost the same.

Next, when the optical disc 1 is tilted downward to the right with respect to the optical pickup 2 as shown in (b), the light amount of the light receiving element 6 located to the left of the light emitting element 5 is lower than that of the light receiving element 7 located to the right. Also decreases, and the light receiving element 6 and the light receiving element 7
Difference occurs in the amount of light. The inclination of the optical disc 1 can be detected by extracting this difference in light amount as the inclination signal of the optical disc 1.

The state (c) is a case where the tilt of the optical disk 1 is corrected by tilting the optical pickup 2 together with the tilt detecting device 4 of the optical disk based on the tilt signal of the optical disk 1. At this time, the light amounts of the light receiving element 6 and the light receiving element 7 become equal, the tilt signal of the optical disc 1 becomes zero, and the state is the same as the state where the optical disc 1 has no tilt.

In this way, the light from the light emitting element 5 attached to the optical pickup 2 is directed to the optical disk 1, and the reflected light is compared with the light receiving elements 6 and 7 provided on both sides of the light emitting element 5 for comparing the received light amounts. The tilt detection device 4 can detect the tilt of the optical disc 1. Based on the signal, the tilt detection device 4 of the optical disc
By tilting the optical pickup 1, the optical disc 1
The inclination of can be corrected.

However, in the structure of such a conventional optical disc tilt detecting device, since the tilts of the optical disc 1 and the optical pickup 2 are detected, the optical pickup device requires a mechanism for tilting the entire optical pickup 2.
Since the heavy optical pickup 2 is tilted, the entire apparatus becomes large.

Next, a second conventional optical disc tilt detecting device will be described. A second conventional example is disclosed in, for example, Japanese Patent Application Laid-Open No. 2-44533.

According to Japanese Unexamined Patent Publication No. 2-44533, light from both ends of an objective lens using a hologram element is applied to an optical disk, and reflected light from the optical disk is received by light receiving elements provided at both ends of the objective lens, and thus the optical disk. The inclination of is detected.

However, in such a conventional structure, it is necessary to provide light receiving elements at both ends of the objective lens, and it is necessary to move the light receiving elements in addition to the objective lens, which increases the weight of the movable portion.

[0019]

In the first conventional structure, only the relative tilt between the optical pickup and the optical disc is detected, so that the optical pickup device tilts the entire optical pickup.

Further, in the second conventional example, since the light receiving elements are provided at both ends of the objective lens, it is necessary to drive the light receiving elements other than the objective lens at high speed, and the weight of the movable portion increases. It had a problem that it did.

An object of the present invention is to provide an optical disk tilt detecting device which solves the above problems and provides a simple structure for detecting the relative tilt between an optical disk and an objective lens movable part.

An optical pickup device using the optical pickup device, based on the signal from the optical disc tilt detection device,
An object of the present invention is to provide an optical pickup device that corrects the tilt of an optical disk by tilting a lightweight objective lens movable part.

[0023]

In order to achieve this object, an optical disk tilt detecting device according to the present invention comprises a light emitting element which emits light toward the optical disk, a light receiving element which receives reflected light thereof, and an objective lens movable part. The light-emitting element that emits light toward and the light-receiving element that receives the reflected light detect the tilts of both the optical disk and the objective lens movable part, and detect the relative tilts of both.

Further, an optical pickup device using the same is constructed such that only the movable part of the objective lens is tilted, based on the tilt detecting device for the optical disc.

Further, the control device corrects the amount of correction different from the tilt of the optical disk by adding it to the movable portion of the objective lens.

[0026]

Since the tilt detecting device for the optical disk can detect the tilts of both the optical disk and the objective lens, the relative tilt of the optical disk and the objective lens can be detected by the difference between them.

Further, in this optical pickup device, the tilt of the optical disk can be corrected with a simple structure by tilting the tilt signal of the tilt detecting device of the optical disk through the tilting means of the objective lens movable portion.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing a first embodiment of an optical disk tilt detecting device and an optical pickup device using the same according to the present invention.

In FIG. 1, reference numeral 1 is an optical disk, 3 is an objective lens, and an objective lens movable portion 10 holding the objective lens 3 has a translational motion in a direction perpendicular to the plane of the optical disk 1 and a radial direction, and a radius. An optical pickup device that reproduces information from the optical disc 1 while having a degree of freedom of tilting movement in the direction is configured.

The objective lens movable portion 10 has a mechanism tilted to the arrow in the figure, and performs signal reproduction while correcting the parallelism between the objective lens 3 and the optical disk 1. This optical disc tilt detection device for detecting the tilt of the optical disc 1 will be described.

A first light emitting element 11 emits light in the direction of the optical disc 1. The light emitted from the first light emitting element 11 is applied to the optical disc 1, and the light amount distribution of the reflected light is first measured.
The light receiving elements 12 and 13 receive the tilt signal of the optical disk 1.

The first light receiving elements 12 and 13 are divided into two in the tilting direction of the optical disk 1, and the image of the reflected light of the first light emitting element 11 on the optical disk 1 is divided in the radial direction. It will receive light. Therefore, when the optical disc 1 tilts in the radial direction, a light amount difference occurs between the first light receiving elements 12 and 13, and the tilt amount of the optical disc 1 can be detected.

A second light emitting element 14 emits light in the direction of the objective lens movable portion 10. The light emitted by the second light emitting element 14 is applied to the objective lens movable portion 10, and the light amount distribution of the reflected light is received by the second light receiving elements 15 and 16 to detect the tilt signal of the objective lens movable portion 10. is doing.

The second light receiving elements 15 and 16 are divided into two parts in the tilting direction of the objective lens movable part 10,
The image of the reflected light at the objective lens movable portion 10 of the second light emitting element 14 is divided in the tilt direction and received. Therefore, when the objective lens movable portion 10 is tilted, a light amount difference occurs between the second light receiving elements 15 and 16, and the objective lens movable portion 10
The inclination amount of can be detected.

Now, the first light receiving elements 12 and 13 and
Since the light amount difference between the second light receiving elements 15 and 16 respectively represents the tilt of the optical disc 1 and the tilt amount of the objective lens movable unit 10, the difference between them is the relative tilt between the optical disc 1 and the objective lens movable unit 10. Become.

By generating this difference in the arithmetic circuit 18, the relative inclination between the optical disk 1 and the objective lens movable portion 10 can be detected. This detailed description will be described with reference to FIG.

FIG. 2 is a side view for explaining the operation of the optical disc tilt detecting device. FIG. 2A shows a state in which there is no relative inclination between the optical disc 1 and the objective lens movable unit 10. At this time, the first light receiving elements 12 and 13 and
The optical paths received by the second light receiving elements 15 and 16 are indicated by arrows. In this state, the light amounts of the first light receiving elements 12 and 13 and the second light receiving elements 15 and 16 are all equal.

Therefore, at this time, the difference output of the first light receiving element (light amount of 12)-(light amount of 13) becomes zero, and the second light receiving element (light amount of 15)-(16 light amount).
Also, the difference output becomes zero.

FIG. 2B shows a state in which the optical disc 1 is tilted. The light amount of the first light receiving element 12 increases, and the light amount of the first light receiving element 13 decreases correspondingly. Second light receiving elements 15 and 16 for detecting the inclination of the objective lens movable portion 10.
2 has the same amount of light as in the state of FIG. Therefore,
At this time, the differential output of the first light receiving element (light amount of 12)-(light amount of 13) becomes positive, and the second light receiving element (1
The difference output of (light amount of 5)-(light amount of 16) remains zero.

FIG. 2C shows a state in which the objective lens movable portion 10 is tilted by the same amount as the tilt of the optical disc 1,
The light amount of the second light receiving element 15 increases by the same amount as the first light receiving element 12, and the light amount of the second light receiving element 16 decreases by the same amount as the first light receiving element 13. Therefore, at this time, the difference output of the first light receiving element (light amount of 12)-(light amount of 13) becomes positive, and the second light receiving element (light amount of 15)-
The difference output of (16 light quantities) is also positive by the same amount.

In the case of FIGS. 2A, 2B, and 2C, the differential of the respective differential outputs is zero in FIG.
It becomes positive in the case of (b), and becomes zero again in the case of FIG. 2 (c).

The state of this tilt signal is shown in FIGS.
FIG. 3 shows the tilt of the optical disc 1 and the first light receiving elements 12, 1.
3 shows a differential output of 3. In addition, in FIG.
And the difference output of the second light receiving elements 15 and 16 are shown.
The tilt of the optical disc 1 and the tilt amount of the objective lens movable unit 10 are described as positive in the direction of FIG.

From FIG. 3 and FIG. 4, when the optical disc 1 is tilted by θ, the first light receiving element (light amount of 12)
-(13 light amount) becomes a positive α. Second at this time
Of the light receiving element (15 light quantity)-(16 light quantity)
Then, it can be seen that the tilt amount of the objective lens movable unit 10 becomes θ which is the same as the tilt of the optical disc 1.

Therefore, if the objective lens movable portion 10 is tilted so that the difference between the difference output of the first light receiving elements 12 and 13 and the difference output of the second light receiving elements 15 and 16 becomes zero,
The tilt amounts of the optical disk 1 and the objective lens movable unit 10 become equal, and the tilt of the optical disk 1 can be corrected.

FIG. 5 shows the correction effect when the tilt of the optical disc 1 is corrected by the tilt of the objective lens 3 based on the aberration showing the optical reproduction characteristic deterioration. The solid line in FIG. 5 shows the relationship between the tilt and the aberration when only the optical disc 1 is tilted. When the inclination of the optical disc 1 becomes large, the aberration that causes the deterioration of the reproduction characteristic also increases almost in proportion.

On the other hand, the dotted line in FIG. 5 shows the relationship between the tilt of the optical disc 1 and the aberration when the objective lens 3 is tilted by the same amount as the optical disc 1. As compared with the case where only the optical disc 1 is tilted, it can be seen that the increase of the aberration is small, which also shows that the difference output of the first light receiving element 1 and the second output
It can be seen that the tilt of the optical disk 1 can be corrected by tilting the objective lens 4 so that the difference from the difference output of the light receiving element of 0 becomes zero.

With the above structure, the first and second tilts for detecting the tilt of the optical disk 1 and the tilt of the objective lens moving part 10 are detected.
Light emitting elements 11 and 14 and first and second light receiving elements 1
By using the optical disc tilt detection device composed of 2, 13, 15 and 16, the relative tilt between the optical disc 1 and the objective lens movable portion 10 can be detected with a simple configuration.

Further, the difference output of the first light receiving element and the second output according to the tilt detected by the tilt detecting device of the optical disk.
By using the optical pickup device in which the objective lens movable unit 10 is tilted so that the difference from the difference output of the light receiving element is zero, the tilt of the optical disc 1 can be corrected with a simple configuration.

Further, in this structure, since the reflecting plate 17 is simply attached to the movable part 10 of the objective lens, an optical pickup device having a light movable part can be realized.

Next, a second embodiment will be described. The difference from the first embodiment is that an optical disc tilt detecting device is provided in which the reflectance of the reflector 17 in FIG. 1 is different from the reflectance of the optical disc 1.

FIG. 6 shows the relationship between the amount of tilt of the objective lens movable part 10 and the aberration when the optical disc 1 has a certain tilt.

In FIG. 6, it can be seen that the aberration is smaller when the tilt amount of the objective lens movable portion 10 is slightly smaller than that of the optical disc 1 than when the tilt amount is the same as that of the optical disc 1.

From this, as the control device of the optical pickup device, the tilt amount of the objective lens 3 with respect to the tilt of the optical disc 1 is reduced at a constant rate to provide a precise control device. I see.

In order to achieve this object, it can be realized by making the reflectance of the reflection plate 17 attached to the objective lens movable portion 10 higher than the reflectance of the surface of the optical disc 1.

FIG. 7 shows the objective lens moving part 10 when the reflectance of the reflection plate 17 is twice the reflectance of the optical disk 1.
And the difference output of the second light receiving elements 15 and 16 are shown on the same scale as in FIG.

As compared with FIG. 3, the inclination of the optical disc 1 is θ, and the first light receiving element (light amount of 12) − (light amount of 13) is α.
When, the second light receiving element (light quantity of 15)-(1
6 is α, the objective lens movable unit 10 is θ /
It becomes 2. By increasing the reflectance of the reflection plate 17 above the reflectance of the optical disc 1 in this way, the tilt of the optical disc 1 is always smaller than the inclination of the optical disc 1 at a constant rate.
The inclination can be corrected by inclining 0.

With the above configuration, the first light receiving element 12,
13 and the second light receiving elements 15 and 16 can realize an optical disc tilt detection device that detects the relative tilt between the optical disc 1 and the objective lens movable unit 10 with a simple configuration, and the reflectance of the reflection plate 17 can be determined by the optical disc 1. When the reflectance is higher than the reflectance of the optical disc 1, the objective lens movable unit 10 can be tilted at a constant rate with respect to the tilt of the optical disc 1, and the tilt can be corrected more accurately.

Next, a third embodiment will be shown. FIG. 8 shows the third
FIG. 3 is a perspective view of an optical disc tilt detection device in the embodiment of FIG. The difference from the first and second embodiments is that the first light emitting element 11, the first light receiving elements 12 and 13, and the second light emitting element 14 and the second light receiving elements 15 and 16 are used as objectives. It is just formed on the objective lens cover 19 including the lens movable portion 10.

In order to prevent the objective lens movable portion 10 from protruding, a cover 19 including the objective lens movable portion 10 is usually attached to such an optical pickup device.

In this way, the first light emitting element 11 and the first light receiving elements 12 and 13 are mounted upward on the cover 19 including the objective lens movable portion 10, and the second light emitting element 14 and the second light receiving element are mounted. By mounting the elements 15 and 16 downward, it is possible to obtain the same effect as that of the first embodiment, and further, it is possible to suppress the protrusion of the objective lens movable unit 10.

Further, the screw 20 holds the cover 19, and the cover 19 can be moved vertically and horizontally about the screw 20 and can be tilted in the same direction as the objective lens movable portion 10.

In FIG. 8, a dotted arrow indicates the tilt direction of the objective lens movable portion 10, and a solid arrow indicates the tilt adjustment direction of the cover 19. In this way, by tilting the cover 19 around the screw 20 in the tilting direction of the objective lens movable portion 10, it is possible to adjust the initial tilt signal to zero during assembly.

With the above structure, by mounting the light emitting / receiving element on the cover 19, the relative tilt between the optical disk 1 and the objective lens movable portion 10 can be detected by the same principle as in the first embodiment, and the objective lens can be detected. It is possible to realize an optical disc tilt detection device capable of preventing the movable section 10 from popping out.

Further, by tilting the cover 19 with the screw 20 holding the cover 19 as the center for adjustment, the initial tilt deviation can be easily corrected.

Next, a fourth embodiment will be shown. FIG. 9 is a perspective view of an optical disk tilt detecting device according to the fourth embodiment. In FIG. 8, a double-sided light emitter 21 emits light from both sides toward the objective lens movable unit 10 and the optical disc 1. Reference numerals 22 and 23 denote light receiving elements, which receive the light of the double-sided light emitting body 21 reflected by the optical disc 1 on the front side and the light of the double-sided light emitting body 21 reflected by the objective lens movable unit 10 on the back side.

The difference output of the light receiving elements 22 and 23 becomes the difference between the tilt of the optical disk 1 and the tilt of the objective lens movable portion 10, and the relative tilt between the optical disk 1 and the objective lens movable portion 10 can be detected with a simple structure. Becomes

As described above, by using the double-sided light emitting body 21 which emits light to both the objective lens movable portion 10 and the optical disc 1, the relative inclination between the optical disc 1 and the objective lens movable portion 10 can be detected with a simple structure. At the same time, the number of parts of the device can be reduced. Further, since the tilt is detected by the same light source, the initial tilt is less likely to occur, and the reliability of the device is improved. Furthermore, by using the light receiving elements such as the light receiving elements 22 and 23 that receive light on both front and back sides, it is possible to realize an optical disc tilt detection device having a simpler configuration.

The double-sided light emitter 21 is a double-sided light emitter that emits light to both the optical disk 1 and the objective lens movable portion 10, but a light-emitting element that emits light to one side may be attached to the front and back sides to obtain the same effect. it can. Further, although the light receiving elements 22 and 23 detect the reflected light from the optical disk 1 and the reflected light of the objective lens movable portion 10 on the front and back sides, respectively, light receiving elements that receive light on only one side may be attached to the front and back sides. Further, even if only the light emitting element and the light receiving element are used on both sides, the inclination can be detected in the same manner.

[0070]

As described above, the reflected light of the light emitting element that emits light in the direction of the optical disc and the light emitting element that emits light toward the objective lens movable portion are received, and the tilts of the optical disc and the objective lens movable portion are detected. By detecting the differential output of the difference between the first and second light receiving elements, it is possible to realize an optical disk tilt detection device capable of detecting the relative tilt between the optical disk and the objective lens movable portion.

Further, by using such an optical disc tilt detecting device, an optical pickup device for tilting the movable part of the objective lens so that the differential output of the first light receiving element and the differential output of the second light receiving element are the same. By doing so, it is possible to realize an optical pickup device that can correct the tilt of the optical disc with a simple configuration.

[Brief description of drawings]

FIG. 1 is a perspective view of an optical disk tilt detection device and an optical pickup device using the same according to a first embodiment of the present invention.

FIG. 2 is a side view showing the operation of the optical disc tilt detection apparatus according to the first embodiment.

FIG. 3 is a characteristic diagram showing the relationship between the tilt of the optical disc and the output of the light receiving element in the first embodiment.

FIG. 4 is a characteristic diagram showing the relationship between the amount of tilt of the movable portion of the objective lens and the output of the light receiving element in the first embodiment.

FIG. 5 is a characteristic diagram showing the relationship between the tilt and the aberration of the optical disc of the optical pickup device in the first embodiment.

FIG. 6 is a characteristic diagram showing the relationship between the amount of tilt of the movable portion of the objective lens and the aberration of the tilt detecting apparatus for the optical disc in the second embodiment of the present invention.

FIG. 7 is a characteristic diagram showing the relationship between the amount of tilt of the movable part of the objective lens and the output of the light receiving element of the tilt detecting device for an optical disk in the second embodiment.

FIG. 8 is a perspective view of an optical disk tilt detection device according to a third embodiment of the present invention.

FIG. 9 is a perspective view of an optical disc tilt detection device according to a fourth embodiment of the present invention.

FIG. 10 is a perspective view of a conventional optical disc tilt detection device and an optical pickup device using the same.

FIG. 11 is a side view showing the operation of the conventional optical disc tilt detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical disc 3 Objective lens 10 Objective lens movable part 11 1st light emitting element 12, 13 1st light receiving element 14 2nd light emitting element 15, 16 2nd light receiving element 17 Reflector plate 18 Differential amplifier

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toru Nakamura 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (6)

[Claims] 1. An objective lens provided so as to face the surface of an optical disc, an objective lens movable portion that holds the objective lens and moves the objective lens, and a first light emitting element that emits light toward the optical disc. A second light emitting element that emits light in the direction of the movable portion of the objective lens; and a second light emitting element that is divided in the tilt direction of the optical disc and receives the reflected light of the first light emitting element from the optical disc. A first light receiving element that detects a difference in the amount of light generated in a splitting element according to the tilt as the tilt of the optical disc; and a second light receiving element that is split in the tilt direction of the objective lens movable portion and is reflected from the reflection plate on the objective lens movable portion. A second light receiving element for receiving the reflected light of the light emitting element and detecting a light amount difference generated in the splitting element according to the inclination of the objective lens movable portion as the inclination amount of the objective lens movable portion; A tilt detecting device for an optical disk, comprising: an arithmetic circuit that generates a difference between the first light receiving element and the second light receiving element to obtain a tilt signal. 2. The tilt detecting device for an optical disc according to claim 1, wherein the reflectance of the reflector is different from the reflectance of the optical disc. 3. A first light receiving element for detecting a tilt of an optical disc, a second light receiving element for detecting a tilt of an objective lens movable part, and a tilt signal of the first light receiving element and the second light receiving element. From the difference between the inclination of the optical disc and the arithmetic circuit that generates a differential signal of the inclination of the objective lens movable portion, and the objective lens is inclined together with the objective lens movable portion based on the differential signal. An optical pickup device that corrects the tilt of an optical disc. 4. A cover including an objective lens movable portion, a first light emitting element which is disposed on a surface of the cover on the optical disk side and emits light toward the optical disk, and receives reflected light from the optical disk. A first split light-receiving element that detects the tilt of the optical disc; a second light-emitting element that is disposed on the surface of the cover on the objective lens movable portion side and emits light toward the objective lens movable portion; A second light receiving element that receives the light emitted from the second light emitting element and is reflected by the movable portion of the objective lens, and detects the tilt of the movable portion of the objective lens; the first light receiving element; An optical disc tilt detecting device, comprising: an arithmetic circuit that generates a difference from the two light receiving elements to obtain a tilt signal. 5. A first and a second light emitting element centering on a holding point that holds a cover including a movable part of an objective lens, and
The optical disk tilt detecting device according to claim 4, further comprising an adjusting screw for adjusting the movement and rotation of the first and second light receiving elements. 6. An objective lens provided so as to face the surface of the optical disc, an objective lens moving part that holds the objective lens and moves the objective lens, and the optical disc is disposed between the optical disc and the objective lens. Direction and the direction of the objective lens movable part, and a double-sided light-emitting body, and light reflected by the double-sided light-emitting body from the optical disc is received by the optical-disk-side surface, and the objective lens of the double-sided light-emitting body is received. A tilt detecting device for an optical disc, comprising: a double-sided light receiving body that receives reflected light from the movable part of the objective lens on the movable part side of the objective lens.