JPS62157334A - Position detector for optical pickup - Google Patents

Abstract

PURPOSE:To make an output signal linear and to obtain a miniaturized lightweight detector suitable for control by installing on a fixed part light emitting element emitting light to both an optical system and a moving reflection part made of a supporting member, and a light receiving element receiving reflected light. CONSTITUTION:When the supporting member 2 and an objective lens 1 are moved in the tracking direction in order to access at a high speed, a reflecting plate 19 installed on the member 2 is displaced together with said movement, and the distribution of the luminous energy of the light receiving element 18 receiving scattered light emitted from the light emitting element 17 is changed. In such a way the reflecting plate 19 is installed on the member 2 moving together with the lens 1, and simultaneously the elements 17 and 18 are installed on the fixed part facing the reflecting plate 19, whereby the detected output signal can be made linear to suit for control. Moreover the device can be scaled down and its weight can be lightened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a position detection device for an optical pickup used for recording and reproducing signals on an optical disc.

[Prior art and problems to be solved by the invention] Conventionally, audio discs, video discs, data discs,
Various pickups have been proposed for recording and reproducing signals on optical discs such as discs.

In such an optical pickup, a light spot is irradiated onto the information recording surface of an optical disc to record or read information. In order to accurately record or reproduce information using this optical pickup, there is a focusing servo that drives the objective lens in the direction of the optical axis of the light so that the focus of the light always matches the information recording surface of the optical disk. It is necessary to apply tracking servo to drive and control the objective lens in the radial direction of the optical disc so as to follow and scan the track or guide groove of the optical disc.

Incidentally, for example, Japanese Patent Application Laid-Open No. 56-130840 discloses a conventional technique regarding an optical pickup having the above structure.

However, in the optical pickup having the above structure, for example, the tracking servo structure is configured such that the tracking error signal is fed back only during normal recording and reproducing operations.

Therefore, for example, during high-speed access, the pickup carriage is moved, but as the carriage accelerates and decelerates, a parallel force is generated in the driving direction of the carriage, causing unnecessary vibrations in the spring cap that supports the objective lens so that it can move in the tracking direction. do. This unnecessary vibration sometimes causes problems such as deteriorating positioning accuracy, making servo control impossible, and delaying access time.

In order to solve the above problem, Japanese Patent Application Laid-Open No. 58-2633
Publication No. 1 proposes a conventional technology related to an optical head configured to detect the objective lens position using an electrostatic capacitive non-contact micro-displacement detection probe and to always perform closed-loop tracking control. There is.

However, since this conventional technology uses an electrostatic 8-output detection sensor, a linear analyzer is required to linearize the output signal, and the sensor diameter is large, making the optical pickup smaller and lighter. was not suitable for Furthermore, there is a possibility that the device may be affected by electromagnetic noise from the outside.

Furthermore, there is also a type of optical system that performs tracking control by rotating a mirror by a predetermined angle using an actuator, as disclosed in Japanese Patent Application Laid-Open No. 57-94942, which reflects a light beam from a light source toward an objective lens. In order to eliminate unnecessary vibrations generated in the mirror during high-speed access, the type pickup uses an angular position detection device to correct the tilt angle of the mirror during access.

However, it is necessary to leave a certain distance between the position detection light source provided in this prior art position detection device and the mirror. Roughly speaking, in order to detect the tilt angle of the mirror using the light flux from this light source, it is necessary to irradiate this mirror with a relatively large light spot. The light-receiving area of the light-receiving element must also be increased.

As a result, the overall size of the device has become larger and its structure has become more complex.

The present invention has been made in view of the above circumstances, and the output signal of the sensor that detects the displacement of the optical system such as the objective lens that occurs during high-speed access is linear and suitable for control, and the small size 11
The purpose of this invention is to provide a position detection device for an optical pickup that can be used as an FD.

[Means and effects for solving the problems] In order to solve the above problems, the present invention provides an optical system that illuminates a recording medium with light emitted from a light source, and a movable support for this optical system. an optical pickup equipped with an actuator that emits light to a reflecting section provided on the optical system or a support member that moves integrally with the optical system; A light-receiving element for receiving the reflected light is provided on a fixed part, thereby linearizing the output signal and making the output signal smaller and lighter.

[Examples] Examples according to the present invention will be specifically described below with reference to the drawings.

1 to 6 relate to the first embodiment of the present invention, in which FIG. 1 is an exploded perspective view of the objective lens actuator portion of the optical pickup, FIG. 2 is a plan view of FIG. 1, and FIG. 1st
Figure 4 is an enlarged view of the position detection device, Figure 5 is a side view of the figure.
The figure is a view taken in the direction of arrow A in FIG. 4, and FIG. 5 is a diagram showing output signal processing.

In these figures, an objective lens 1 that irradiates a light spot onto a recording medium such as an optical disk is fitted and attached to a support member 2. As shown in FIG. This support member 2 is displaced in a focusing direction F parallel to the optical axis of the objective lens 1 to converge the light spot onto the recording medium and to collect the information 1 to 1 on the recording medium.
The objective lens support member 2 is supported so that the optical spot follows the information track by displacing it downward in the tracking direction perpendicular to the rack and optical axis. 1! It is connected to the base 3 via a structure. This support mechanism includes a pair of focusing plate bones 4a and 4b, a relay member 5,
It is composed of a pair of tracking leaf springs 6a and 6b. a pair of focusing leaf springs 4a;
4b are the focusing direction F and the tracking direction T while facing each other parallel to each other as seen in the focusing direction F.
R 2 a d3 and 2b each having one end opened in the side wall of the support member 2 so as to extend in a direction perpendicular to the
The other end is fitted into upper and lower grooves 5a and 5b formed in the relay member 5. Further, the pair of tracking leaf springs 6a and 6b are arranged at one end of each so as to extend in a direction substantially orthogonal to the focusing direction F and the tracking direction T while facing each other at a certain angle α in the tracking direction T. A boss 7 is fitted into left and right grooves 5C and 5d formed in the relay member 5, and the other end is formed integrally with the base 3.
and 8 are fitted into grooves 7a and 8a. The distance between one end of the above-described pair of tracking leaf springs 6a and 6b on the relay member 5 is longer than the distance between the other ends of the posts 7 and 8. α is preferably about 30°, for example. In this way, the objective lens 1 moves in the focusing direction F and the tracking direction T.
movably supported. A pair of focusing coils 9b and 9b are fixed to the side surface of the support member 2 facing in the tracking direction T, and a pair of tracking coils 10aJ5 and 1ob are integrally attached to the outside of these focusing coils 9a and 9b. There is. The focusing coils 9a and 9b have a "mouth-shaped" shape when viewed in the focusing direction F, while the dragging coils 10a and 10b have a "U-shaped" shape when viewed in the focusing direction F. A magnetic field generating member that generates a magnetic field that cooperates with these focusing coils 9a, 9b and racking coils 10a, 10b is a pair of yokes 11 and 1 made of magnetic material.
2, and the legs 11a and 11 on both sides of one yoke 11.
Permanent magnets 13aJ3 and 13b mounted along b,
The permanent magnets 14a and 14b are attached along the legs 12a and 12b on both sides of the other yoke 12. These yokes 11 and 12 are fixed to the base 3 in such a way that their central legs 11c and 12c are inserted into one of the casing coils 9a and 9b, respectively. Focusing coil 9a, 9
The lead wires (only one of which is shown in FIG. 1) connected to the tracking coils 10a, 19b are connected to the terminals provided on the side surface of the support member 2, and the rear leaf springs 4a, 4b,
6a and 6b, and is fixed to the base 3 by passing through the hole 5e formed in the relay member 5.
5 and is further connected to the circuit from here.

On the other hand, a holding member 16 whose one end is fixed to the end of the base 3 is provided in a portion facing the support member 2 . This holding member 16 is formed into a plate shape, and a light emitting element 17 and a light receiving element 18 are fixed to the portion facing the supporting member 2. The light receiving element 17 has light receiving areas 18a and 18b divided into two in the tracking direction.

A reflecting plate 19 is fixed to the side surface of the support member 2 facing the light emitting element 17 and the light receiving element 18.

This reflecting plate 19 is formed in a substantially circular shape, and reflects the light emitted from the light emitting element 17, and reflects the light emitted from the light receiving element 1.
7 light receiving area 18a.

A circular irradiation spot 20 is formed at 18b. Note that the light receiving areas 18a, 18 of the light receiving element 18
A current proportional to the output difference signal of the photoreceptor detected at point b flows through the tracking coils 10a and 10b.

In such a configuration, during normal recording and reproduction, when a focusing drive current is passed through the focusing coils 9a and 9b, the focusing coils 9a and 9b apply a force in the focusing direction F due to the interaction with the magnetic field passing through these coils 9a and 9b. The receiver, support member 2, and objective lens 1 are displaced in the focusing direction F due to the deflection of the pair of focusing leaf springs 4a and 4b. or,
When a tracking drive current is applied to the tracking coils 10a and 10b, the support member 2 and the objective lens 1 are displaced in the tracking direction T in a similar manner.

Next, when the support member 2 and the objective lens 1 move in the tracking direction T for high-speed access operation, etc.,
Along with the movement, the reflection plate 19 is displaced, and the distribution of light 1 that is emitted from the light emitting element 17 and received by the light receiving element 18 is changed. When the objective lens 1 is not displaced, the irradiation spot 20 from the light emitting probe 17 is in the light receiving area is
If a and i8b are located so that they have the same area, the output voltage difference will be O. Moreover, when the objective lens is displaced, the irradiation spot 20= at a position proportional to the displacement
The light receiving area 18 becomes a light intensity distribution proportional to the displacement.
The output voltage difference between a and 18b is proportional to the displacement of the objective lens 1, as shown in FIG. A current proportional to this output voltage difference is fed back to flow through the tracking coils 10a and 10b to form a closed loop of a number-bo system, and the displacement of the objective lens 1 in the tracking direction T is controlled to be maintained at a zero position. Therefore, unnecessary vibrations of the objective lens 1 that occur during high-speed access can be prevented.

In this embodiment, one reflecting plate that moves together with the objective lens 1 is provided, and a light emitting element 17 and a light receiving element 18 are provided on a fixed part facing this one reflecting plate, so that the detection υ The output signal g can be made linear, and the size and weight can be reduced.

Incidentally, in the first embodiment, as shown in FIG.

A similar effect can also be obtained by disposing a collimator lens 21 between the light emitting element 17 and the reflecting plate 19 to obtain a parallel light beam. In addition, the anti-plate 19 (as shown in FIG. 8) may be attached to move together with the objective lens 1, for example, attached to the outer frame of the objective lens actuator 22 in which the objective lens that moves at an eccentric position is disposed. The same effect can be obtained even if

FIG. 9 relates to a second embodiment of the present invention, in which FIG. 9(a) is an explanatory diagram of a position detection device portion, and FIG. 9(b) is a view taken in the direction of arrow A in FIG. 9(a). Incidentally, parts or members that are the same as or correspond to those in the first embodiment are denoted by the same reference numerals, and a description thereof will be omitted. The same applies to the description of the subsequent embodiments.

In this embodiment, the width J21 in the optical axis direction of the rectangular mirror 31 that moves in the X direction together with an objective lens (not shown) is
A parallel light beam with a width of 12 larger than that of the light beam is incident on the reflecting plate 31, and a part of the reflected light is received by the light receiving element 32 to form an irradiation spot 33.

In such a configuration, when the reflecting plate 31 moves in the X direction, the reflected light also moves in the X direction, and as a result, the size of the irradiation spot 33 on the light receiving surface of the light receiving element 32 changes. Therefore,
The output signal q corresponding to the movement of the reflection plate 31 is 15t.

In this embodiment, a similar effect is obtained when the reflecting plate 31 is moved in the Y direction, which is perpendicular to the X direction.

Furthermore, the light receiving element 32 does not require divided light receiving areas. Roughly speaking, the X direction or Y direction is the tracking direction T,
It can be moved in any direction in the focusing direction F.

FIG. 10 relates to the third embodiment of the present invention, and FIG. 10(a)
10(b) is an explanatory diagram of the position detection device, and FIG. 10(b) is the same figure (a).
It is A arrow 81 diagram of.

In this embodiment, as in the second embodiment, a part of the parallel light beam incident on the reflecting plate 41 moving in the X direction is blocked by the light shielding plate 42 to prevent light from hitting one end of the reflecting plate 31. be done. Then, the reflected light is incident on the light receiving element 43 having the light receiving areas 43a and 43b divided into two in the X direction so as to form an irradiation spot 44.

In such a configuration, when the anti+3-1 temporary 41 moves in the X direction, the light 04 spot 1-44 moves in the x7 direction without changing its magnitude. Therefore, an output signal is obtained in the light receiving regions 43a and 43b of the light receiving element 43 in which the output voltage difference corresponds to the amount of movement of the reflecting plate 41.

FIG. 11 relates to the fourth embodiment of the present invention, and FIG. 11(a)
11(b) is an explanatory diagram of the position detection device, and FIG. 11(b) is the same figure (a).
The A arrow view and FIG. 11(C) are diagrams that do not show the output light distribution of the light emitting element.

In this embodiment, a light shielding plate 52 is provided to form a part of the parallel light flux incident on the reflective plate 51 moving in the Y direction into a round shape and to block the light, so that the light hits the center of the reflective plate 51. do. Then, C1, the reflected light is transmitted to a light receiving element 53F having light receiving areas 53a and 53b divided into two in the direction perpendicular to the Y direction.
The light is incident on the beam so as to form a circular irradiation spot 54.

In such a configuration, when the reflection plate 51 moves in the Y direction, the irradiation spot 54 moves in a direction perpendicular to the Y direction without changing its size. Therefore, an output signal is obtained in which the output voltage difference between the light receiving regions 53a and 53b of the light receiving element 53 corresponds to the amount of movement of the reflecting plate 51. The output light distribution is shown in Figure 11 (C
), the same effect can be obtained without the light shielding plate 52 by using a light emitting element in which the light is strongest at the center and weaker toward the periphery.

FIG. 12 relates to the fifth embodiment of the present invention, and FIG. 12(a)
12(b) is an explanatory diagram of the position detection device, and FIG. 12(b) is the same figure (a).
FIG.

In this embodiment, two opposite surfaces 61a and 61b having an angle of movement in the Y direction are used as a right-handed reflecting plate 61, and a light shielding plate 6
2, a portion of the light is blocked so that the light hits the center of the repelling plate 61. Then, the repulsed light is reflected from the anti-q4 surface 6
1a and 61b, and are used to form irradiation spots 64.64' on two light receiving elements 63.63-, which are respectively divided in the direction perpendicular to the Y direction.

In such a configuration, each light receiving element 63°63'
The light receiving areas 63 a , 63 b , 6 divided into two
By summing the difference between the output voltages of 3=a and 63'b, an output signal corresponding to the movement of the reflecting plate 61 can be obtained.

In this case, the output voltage is doubled and the detection sensitivity is increased.

FIG. 13 relates to the sixth embodiment of the present invention, and FIG. 13(a)
13(b) is an explanatory diagram of the position detection device, and FIG. 13(b) is the same figure (a).
FIG.

In this embodiment, light blocked by a light shielding plate 62 enters a reflecting plate 61 formed in the same manner as in the fifth embodiment, and the reflected light hits two light receiving elements 71, 71', respectively, at irradiation spots 72. 72".

In such a configuration, when the reflecting plate 61 moves in the X direction, the difference between the two output voltages of the light receiving elements 71 and 71- is 1q, which is an output signal corresponding to the amount of movement of the reflecting plate 61.

FIG. 14 relates to the seventh embodiment of the present invention, and FIG. 14(a)
is an explanatory diagram of the position detection device, and Figure 1n14 (b) is the same diagram (a
) is a view taken in the direction of arrow B.

In this embodiment, light that has been blocked by a light shielding plate 81 is incident on a reflecting plate 82 formed in a prism shape, and the reflected light is directed in a perpendicular direction and is irradiated onto a C light receiving element 83 to spot an irradiated spot. 84. This light receiving element 83 has light receiving areas 83a and 83b divided into two in the X direction of the reflecting plate 82.

ing.

With such a configuration, an output signal corresponding to the movement 61 of the foul plate 82 in the X direction or the Y direction can be obtained.

As shown in FIG. 15, in the seventh embodiment, even if the light shielding plate 81 is not provided and a parallel light beam is irradiated, the 7. - Output reliability can be obtained.

FIG. 16 relates to the eighth embodiment of the present invention, and FIG. 16(a)
is an explanatory diagram of the position detection device, FIG. 16 (bl is the same figure (a)
FIG.

In this embodiment, the light receiving element 91 is irradiated with a parallel light flux entering the reflection plate 82 in a perpendicular direction to form an irradiation spot 92. It has become.

This light receiving element 91 has a light receiving area 91a divided into two in the Z direction (direction perpendicular to the plane of the drawing) perpendicular to the incident light.

I am using 91b.

In such a configuration, the output signal corresponding to the amount of movement of the reflection plate 82 in the Z direction is increased by 1q.

FIG. 17 relates to the ninth embodiment of the present invention, and FIG. 17(a)
17(b) is an explanatory diagram of the position detection device, and FIG. 17(b) is the same figure (a).
FIG.

In this embodiment, a parallel light beam incident on a reflecting plate 82 formed in the same manner as in the seventh embodiment is directed in a right angle direction and is incident on a light receiving element 101 to form an irradiation spot 102. This light receiving element 101 is
Light-receiving areas 101a and 101b each divided in the direction
, 101c, and 101d.

In such a configuration, (101a+101b) −(1
01c −+ 101 d), the movement H1 of the reflection plate 82 in the X direction becomes <1018+1016)−
(10'l b+101 c) allows the reflection plate 82 to move in two directions? lJ fa is detected.

FIG. 18 relates to a tenth embodiment of the present invention, and FIG.
18(b) is a perspective view of a reflection plate of the position detection device, and FIG. 18(b) is a diagram without showing a light receiving element.

In this embodiment, similar to the sixth embodiment in FIG.
The reflected light is incident on the reflection plate 111 on the right side of d, and the reflected light is distributed to four light-receiving elements 112a with each side common to the outside of the quadrilateral.
112b, 112(:.

An irradiation spot is formed at 112d.

Such a configuration r works similarly to the sixth embodiment, and the amount of movement of the reflecting plate 111 in the X direction and the Z direction is detected.

Incidentally, in the above embodiment, the reflector plate 19, 31°41.5
1,61,82.11. Light receiving cable 18゜32.43,5
2,63.63=,71.71+.

83.91, 101, 112 and the shape of the required light are not limited to those in the example.3. Moreover, what detects the position is not limited to the objective lens 1 as in the first embodiment, but may be other optical elements such as a prism or a light emitting element. Furthermore, as long as the reflector reflects light in the opposite direction, it may be the part whose position is to be detected or the supporting member itself, and the reflectance may be increased by plating the member, etc. It is sufficient if the reflective part is Roughly, part of the reflective part (-11) coating with low I ratio or 04
It is also possible to reflect only a specific portion by applying a protective film or the like.

[Effects of the Invention] According to the present invention, light is emitted to the anti-aI portion provided on the movably supported optical system of the optical pickup or on the support member that moves together with the optical system. Since the light emitting element and the light receiving element that receives the reflected light after the light from the light emitting element is reflected by the light emitting part are provided in a fixed part, the output signal is linear and suitable for control.
In addition, there is an effect that the size and weight can be reduced.

[Brief explanation of drawings]

FIG. 1 to FIG. 6 relate to the first embodiment of the present invention.
The figure is an exploded perspective view of the objective lens actuator section.
The figure is a plan view of Fig. 1, Fig. 3 is a side view of Fig. 1, Fig. 4 is an enlarged view of the position detection device part, Fig. 5 is a view taken from arrow A in Fig. 4, and Fig. 5 is an output 7 is a diagram showing another position detection device, FIG. 8 is a diagram showing another position detection device, FIG. 9 is a diagram showing another position detection device, and FIG. Figure 9 (a) is an explanatory diagram of the position detection device part, and Figure 9 (b) is the same figure (a).
Fig. 10 is a Δ arrow view of , Fig. 10 relates to the third embodiment of the present invention, Fig. 10 (a) is an explanatory diagram of the position detection device, Fig. 10 (b)
11 is a view in the direction of arrow A in FIG. 11(a), FIG. 11 relates to the fourth embodiment of the present invention, FIG. A view of a), Fig. 11 (C)
12 is a diagram showing the output A4 light distribution of the light emitting element, FIG. 12 is related to the fifth embodiment of the present invention, FIG. 12(a) is an explanatory diagram of the position detection device, and FIG. 12(b) is the same diagram ( A view of a), 1st
3 relates to the sixth embodiment of the present invention, FIG. 13(a) is an explanatory diagram of the position detection device, and FIG. 13(b) is A of the same diagram (a).
The arrow view and FIG. 14 relate to the seventh embodiment of the present invention.
Figure 14 (a) is an explanatory diagram of the position detection device, and Figure 14 (b) is l
Fig. 15(a) is an explanatory diagram of the position detection device, Fig. 15(b) is B in Fig. 15(a).
The arrow view and FIG. 1G relate to the eighth embodiment of the present invention, and the 16th embodiment
FIG. 16(a) is an explanatory diagram of the position detection device, FIG. 16(b) is a view taken in the direction of arrow B in FIG. 16(a), FIG. ) is an explanatory diagram of the position detection device, No. 17
Figure (b) is a view taken from arrow B in Figure (a), Figure 18 relates to the tenth embodiment of the present invention, Figure 18 (a) is a perspective view of the reflector of the position detection device, Figure 18. (b) is a diagram showing a light receiving element. 1... Objective lens 2... Support member 16...
・Holding member 17...Light emitting element 18.32.4
3.52, 63.63-. 71°71', 83.91
... Light receiving element 19.31, 41.51, 61.82 ... Reflector plate 1
Figure 2 Figure 3 Figure 15 (a) (b) Figure 16 (a) (bl Figure 17 (a) (b) Figure 18 (a) (b) +1Zc Hand M, '4ril normal center t (spontaneous) December 19, 1985 1, Incident indication 1985 patent application No. 180825
No. 2, Title of the invention Position detection device for optical pickup 3, Relationship with the case of the person making the amendment Representation of the patent applicant 2 111 Min. 5, Date of amendment order = 1 (Voluntary) 1, Specification No. On page 11, line 18, I corrected it by saying, ``Same area as r8b...''. 2. On page 14 of the specification, lines 19 to 20 [...
・The large serrations do not change and move in the X direction. ...], there is a change l on the light receiving area 43a.
First, only the light receiving area /13b changes. ..." I corrected it. 3. In the third line of page 21 of the specification, the phrase "may be done." It is possible to omit the light-shielding plate.'' 4. In the 8th line of the 23rd page of the light, r18.32°/1.3.52,63.63=,71.
J is r18.32.43.53.63.63-.
71°” and corrected it first. 5. r71 +, 83°9 on page 23, line 9 of the specification
1, . . . light receiving element" is r71-. 83.91.
101.112...Photo-receiving element" and correct it. 6. N9,31°41. on page 23, line 10 of the specification.
51, 61, 82. ...reflector" r19.3
1.41.51, 61.82.111...Anti (G) plate" is corrected. Above Figure 1 Figure 4 R Figure 11 (b) Procedure ``n Stop (Method) January 30, 1985 9 1. Indication of the case Special revision application No. 180825 of 1985
No. 2, Title of the invention: Optical pickup position detection device 3, Relationship to the case of the person who made the amendment Patent applicant representative Satoshi Shimoyama Department 5: Date of amendment order January 27, 1985 6: Amendment Subject: Brief description of drawings column 1, specification No. 21
On the 19th line of the page [Figure 1 shows the principle, Figure 17 shows the other...]
The 64th is a diagram showing output processing,
Figure 7 is the other one...'' and corrected it first. that's all

Claims (4)

[Claims] (1) In an optical pickup that includes an optical system that irradiates a recording medium with light emitted from a light source and an actuator that movably supports this optical system, the optical pickup moves integrally with the optical system or the optical system. The fixed part is provided with a light emitting element that emits light to a reflective part provided on the supporting member, and a light receiving element that receives the reflected light when the light from the light emitting element is reflected by the reflective part. Optical pickup position detection device. (2) The position detecting device for an optical pickup according to claim 1, wherein the reflecting section is a reflecting plate fixed to a supporting member of the objective lens. (3) The position detection device for an optical pickup according to claim 1, wherein the light receiving element has a light receiving area divided into a tracking direction and a focusing direction. (4) The position detection device for an optical pickup according to claim 1, wherein the reflecting section is a reflecting plate that reflects incident light in a right angle direction.