JPH03290827A - Optical pickup - Google Patents

Abstract

PURPOSE:To facilitate the assembly by using a zigzag lattice-like reflecting plate in which a first and a second reflecting parts and a first and a second non-reflecting parts are provided on the opposite angles, respectively on the lens holder side, and two pairs of light emitting/light receiving elements. CONSTITUTION:The optical pickup is provided with a sensor 58 consisting of a zigzag lattice-like reflecting plate 57 in which a first and a second reflecting parts 57a, 57b and a first and a second non-reflecting parts 57c, 57d are provided on the opposite angle, respectively on a lens holder 46 side, a first and a second light emitting elements 58a, 58b for emitting a light bean for detecting a lens position on a base 31 side, and a first and second light receiving elements 58c, 58d for receiving a light beam reflected by the reflecting plate 57. In such a way, it will suffice that a line L in the vertical direction of the reflecting plate 57 and a line l in the vertical direction of a photosensor substrate 58 are aligned, and the assembly is facilitated.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a lens holder having an objective lens, and a base connected to the lens holder via support means that movably supports the lens holder. The present invention relates to an optical pickup that reads and/or writes information by irradiating a laser beam from a light emitting source onto a recording medium through the objective lens.

(Background of the Invention) Next, a conventional example will be explained using the drawings. Fig. 5 is a sectional view of a conventional optical pickup, Fig. 6 is a plan view of Fig. 5 with the cover removed, Fig. 7 is a side view of the lens position sensor in Fig. 5, and Fig. 8 is a side view of the lens position sensor in Fig. 5. 7th
FIG. 2 is a plan configuration diagram in the figure.

First, in FIGS. 5 and 6, reference numeral 1 denotes a base of an optical pickup whose both sides are slidably engaged with guide bars 2.3. A linear motor (not shown) is provided on the base 1, and the base 1 is guided by guide bars 2 and 3 to move. A hole 1a is formed approximately in the center of the base 1. 4 is a sub-base in which a hole 4a opposite to the hole 1a is bored. On this sub-base 4, approximately Y-shaped yokes 5 and 6 are attached. A magnet 7.8 is attached to the yoke 5, and a magnet 9.10 is attached to the yoke 6, forming magnetic circuits (1) and (2), respectively.

Next, the support means will be explained. The base end of 11.12 is attached to the yoke 5.6, and the distal end is attached to the relay member 13.
It is a leaf spring connected to. Reference numerals 14 and 15 designate leaf springs whose proximal ends are attached to the relay member 13 and whose distal ends are connected to the lens holder 16. An objective lens 23 is attached to the lens holder 16.

Attached to the side surface of the lens holder 16 are coils 17 and 18 arranged in the magnetic gap between the magnetic circuits I and II. Furthermore, the coil 17 is the focusing coil 1
7a and tracking coils 17b and 117c. Similarly, the coil 18 is the focusing coil 1
8a and tracking coils 18b and 18c.

25 is a mirror holder attached to the lower surface of the base 1. A flange portion 25a is provided on the side surface of this mirror holder 25.
is formed in the flange portion 25a, and a hole 25b is formed in the flange portion 25a.
are drilled in three locations.

On the other hand, a screw hole 1c is formed in the lower surface of the base 1, facing the hole 25b drilled in the flange portion 25g.

The mirror holder 25 is attached to the lower surface of the base 1 using a screw 24 that loosely fits into the hole 25b of the flange portion 25a and screws into the screw hole 1c of the base l.

Inside the mirror holder 25, a pair of pentamirrors 19 and 20 are disposed that provide a 90'' declination angle between the input optical axis and the output optical axis.The laser beam from a semiconductor laser (not shown) is The light travels in the direction of the objective lens 23 via a pair of pentamirrors 19 and 20.

Further, 21 is a recording medium, 22 is a lens holder 16. Magnetic circuit I.

■It is a cover that covers.

Next, the lens position sensor 26 will be explained. The lens position sensor 26 includes a reflective plate 27 provided on the lens holder 16 side and a pair of reflective photosensor substrates 28 provided on the base 1 side.

Furthermore, the lens position sensor 26 will be explained using FIGS. 7 and 8. In the figure, the reflective plate 27 has a reflective part 27a in the center and non-reflective parts 27b and 27c on both sides of the reflective part 27a (in FIGS. 7 and 8,
The area indicated by diagonal lines) is formed. On the other hand, the reflective photosensor substrate 28 includes first and second light emitting elements 28a and 28b that emit light beams, and a first light emitting section 28a.
The first light receiving element 28 receives the light beam emitted from the
A second light receiving element 28d receives the light beam emitted from the C1 light emitting element 28b.

Next, the operation of the above configuration will be explained. The base 1 is moved in the track direction of the recording medium 21 by a linear motor (not shown) while being guided by a guide bar 2.3. After moving to the target track, information is read/written to the recording medium 21.

At this time, focusing is performed by a focusing control circuit (not shown) using the focusing coil 17a.

A current is applied to 18a. Then, thrust in the focusing direction is generated in the coil 17°18, and the lens holder 16
moves in the focusing direction (in the direction of arrow F in FIG. 5) against the elastic force of leaf springs 14 and 15. and,
When the application of this current is removed, the lens holder 16 returns to its original position.

Next, for tracking, a tracking control circuit (not shown) uses tracking coils 17b and 17c.

A current is applied to 18b and 18c. Then, coil 17
．． A thrust force in the tracking direction is generated at the lens holder 18, and the lens holder 16 moves in the tracking direction (in the direction of arrow T in FIG. 6) against the elastic force of the leaf springs 11 and 12. Then, when the application of this current is removed, the lens holder 16 returns to its original position.

The laser beam emitted from the semiconductor laser is then moved by pentamirrors 19 and 20 so that its traveling direction is 90°.
It is bent and projected onto the recording medium 21 via the objective lens 23.

Next, the lens position sensor 26 will be explained. 7 and 8 show the lens holder 16 at the neutral point. At this time, the light receiving elements 28c, 28
The same amount of light flux is incident on d. Therefore, the difference between the two is 0.

Here, as information continues to be read/written, the track of the recording medium changes. At this time, the lens holder 16 itself moves and deviates from the neutral point. Further, when the entire optical pickup moves at high speed to the target track, the lens holder 16 shifts from the neutral point due to acceleration.

In this way, if the lens holder 16 deviates from the neutral point,
The reflecting plate 27 moves in the left-right direction from these figures.

As a result, the balance between the amounts of light beams incident on the two light receiving elements 28C128d is disrupted.

In other words, it can be positive or negative.

Therefore, by looking at the difference in the amount of luminous flux incident on the light receiving element 28c and the light receiving element 28d, it is possible to see in which direction and by how much the lens holder 16 is moving.

(Problem to be Solved by the Invention) The sensitivity of the lens position sensor 26 is determined by the light emitting element 28a.
, a light receiving element 28c, and a light emitting element 28b.

If the distance from the light-receiving element 28d is a predetermined value, the characteristics will be as shown by the solid line in FIG. 9, but if the distance is out of order,
The characteristics become as shown by the dotted line in FIG. 9, and the sensitivity decreases.

In the conventional example with the above configuration, when assembling, since the width of the reflecting portion 27a of the reflecting plate 27 is fixed, the distance between the light emitting element 28a, the light receiving element 28c, and the light emitting element 28b, the light receiving element 28d is reflected. There is a problem in that a large number of man-hours are required to match the size of the portion 27a.

The present invention has been made in view of the above problems, and an object thereof is to provide an optical pickup that is easy to assemble.

(Means for Solving the Problems) The present invention for solving the above problems includes a lens holder having an objective lens, and a base connected to the lens holder via a support means that movably supports the lens holder. In an optical pickup that reads and/or writes information by irradiating a laser beam from a light emitting source onto a recording medium through the objective lens, the first . The second reflecting section and the first reflecting section. 11. having a second non-reflective portion; a houndstooth reflector in which a second reflective part and a first and second non-reflective part are arranged diagonally, and a lens position of the objective lens, which is provided vertically on the base side; The first one emits a light beam for detection. A second light emitting element and a first light emitting element are provided vertically on the base side and receive light beams emitted from the first and second light emitting elements and reflected by the reflecting plate. 'l
It has a lens position sensor consisting of a sensor consisting of a light receiving element s2 and a sensor consisting of a light receiving element s2.

(Function) In the optical pickup of the present invention, the light beam emitted from the first light emitting element is reflected by the first reflecting section to the first non-reflecting section and enters the first light receiving element.

Further, the light beam emitted from the second light emitting element is reflected by the second reflective part or the second non-reflective part and enters the second light receiving element.

(Example) Next, one embodiment of the present invention will be described using the drawings.

FIG. 1 is a side configuration diagram of an optical big-ass lens position sensor illustrating an embodiment of the present invention, FIG. 2 is a plan configuration diagram in FIG. 1, and FIG. 3 is a sectional view of an optical pickup of this embodiment. FIG. 4 is a plan view of FIG. 3 with the cover removed.

First, in FIGS. 3 and 4, reference numeral 31 is a base of an optical pickup having both sides slidably engaged with guide bars 32 and 33. As shown in FIG. A linear motor (not shown) is provided on the base 31, and guide bars 32, 33
You will be guided to move. A hole 31a is formed approximately in the center of the base 31. 34
A sub-base is provided with a hole 34a facing the hole 31a. On this sub-base 34, approximately Y-shaped yokes 35 and 36 are attached. The yoke 35 has a magnet 37.38, and the yoke 36 has a magnet 39.4.
0 is attached to each, and each magnetic circuit I
, II are formed.

Next, the support means will be explained. Reference numerals 41 and 42 designate leaf springs whose base ends are attached to the yokes 35 and 36 and whose distal ends are connected to the relay member 43.

Reference numerals 44 and 45 designate leaf springs whose base ends are attached to the relay member 43 and whose distal ends are connected to the lens holder 46. An objective lens 53 is attached to the lens holder 46.

Attached to the side surface of the lens holder 46 are coils 47 and 48 arranged in the magnetic gaps of the magnetic circuits (1) and (2). Further, the coil 47 includes a focusing coil 47a and a tracking coil 47b147c. Similarly, the coil 48 includes a focusing coil 48a and tracking coils 48b and 48c.

55 is a mirror holder attached to the lower surface of the base 31. A flange portion 55 is provided on the side surface of this mirror holder 55.
A is formed in the flange portion 55a, and a hole 55 is formed in the flange portion 55a.
B is drilled in three places.

On the other hand, a screw hole 31c is formed in the lower surface of the base 31, facing the hole 55b drilled in the flange portion 55a. Then, using the screw 54 that loosely fits into the hole 55b of the flange portion 55a and screws into the screw hole 31c of the base 31,
The mirror holder 55 is attached to the lower surface of the base 31.

Inside the mirror holder 55, a pair of pentamirrors 49 and 50 are disposed that provide a 90'' declination angle between the input optical axis and the output optical axis.The laser beam from a semiconductor laser (not shown) is The light travels in the direction of the objective lens 53 via a pair of pentamirrors 49 and 50.

Further, 51 is a recording medium, 52 is a lens holder 46. Magnetic circuit I.

■It is a cover that covers.

Next, the lens position sensor 56 will be explained. The lens position sensor 56 includes a reflective plate 57 provided on the lens holder 46 side and a pair of reflective photosensor substrates 58 provided on the base 31 side.

Furthermore, the lens position sensor 56 will be explained using FIGS. 1 and 2. In these figures, the reflecting section 57 is the first. The second reflecting portions 57g, 57b and the first reflecting portions 57g, 57b. Second non-reflective portions 57c, 57d (in FIGS. 1 and 2,
(the area indicated by diagonal lines) and the first. Second reflective section 57a
, 57b and the first degree second non-reflective portion 57c, 57
d are formed in a houndstooth check pattern, each arranged diagonally.

On the other hand, the reflective photosensor substrate 58 is provided in the vertical direction and has a first photo sensor substrate 58 that emits a light beam. Second light emitting element 58
a, 58b, which are also provided in the vertical direction, and are emitted from the first and second light emitting elements 58a, 58b, and the reflection plate 57
The first one receives a light beam reflected by the first. The light beam reflected by the reflecting plate 57 is directed upward and downward toward the second light receiving element. Second light emitting elements 58a, 58
The first one receives the light beam from b. Second light receiving element 58c
, 58d.

Next, the operation of the above configuration will be explained. The base 31 is moved in the track direction of the recording medium 51 by a linear motor (not shown) while being guided by guide bars 32 and 33. When the target track is reached, the recording medium 5
A data read/write is performed for 1.

At this time, focusing is performed by a focusing control circuit (not shown) using a focusing coil 47a.

A current is applied to 48a. Then, thrust in the focusing direction is generated in the coil 47° 48, and the lens holder 46
moves in the focusing direction (in the direction of arrow F in FIG. 3) against the elastic force of leaf springs 44 and 45. and,
When the application of this current is removed, the lens holder 46 returns to its original position.

Next, for tracking, a tracking control circuit (not shown) uses tracking coils 47b and 47c.

A current is applied to 48b and 48c. Then, coil 47
．． A thrust force in the tracking direction is generated at the lens holder 48, and the lens holder 46 moves in the tracking direction (in the direction of arrow T in FIG. 4) against the elastic force of the leaf springs 41 and 42. Then, when the application of this current is removed, the lens holder 46 returns to its original position.

The laser beam emitted from the semiconductor laser is then moved by a pentamirror 49.50 so that its traveling direction is 90°.
It is bent and projected onto the recording medium 51 via the objective lens 53.

Next, the lens position sensor 56 will be explained. 1 and 2 show the lens holder 46 at a neutral point. At this time, the light receiving elements 58c, 58
The same amount of light flux is incident on d. Therefore, the difference between the two is 0.

Here, as information continues to be read/written, the track of the recording medium changes. At this time, the lens holder 46 itself moves and deviates from the neutral point.

Further, when the entire optical pickup moves at high speed to the target track, the lens holder 46 shifts from the neutral point due to acceleration.

In this way, if the lens holder 46 deviates from the neutral point,
The reflecting plate 57 moves in the left-right direction from these figures.

This causes an imbalance in the amount of light beams incident on the two light receiving elements 580° 58d.

In other words, it can be positive or negative.

Therefore, by looking at the difference in the amount of luminous flux incident on the light receiving element 58c and the light receiving element 58d, it is possible to see in which direction and by how much the lens holder 56 is moving.

According to such a configuration, when assembling, the reflector 57
The adjustment is completed simply by aligning the vertical line L (see FIG. 1) of the photosensor substrate 58 with the vertical line p (see FIG. 1) of the photosensor substrate 58. Therefore, assembly becomes easy.

(Effects of the Invention) As described above, according to the present invention, the first lens is provided on the lens holder side. a second reflective part and a first second non-reflective part; The second reflecting section and the first reflecting section. a houndstooth reflector plate in which second non-reflective portions are arranged diagonally;
The first lens is provided vertically on the base side and emits a light beam for detecting the lens position of the objective lens. a second light emitting element, and a first light emitting element provided vertically on the base side and receiving a light beam emitted from the first and second light emitting elements and reflected by the reflection plate. By providing the lens position sensor consisting of the second light receiving element and the sensor, it is possible to realize an optical pickup that is easy to assemble.

[Brief explanation of the drawing]

FIG. 1 is a side configuration diagram of a lens position sensor of an optical pickup illustrating an embodiment of the present invention, FIG. 2 is a plan configuration diagram in FIG. 1, and FIG. 3 is a sectional view of the optical pickup of this embodiment. Fig. 4 is a plan view of Fig. 3 with the cover removed; Fig. 5 is a sectional view of a conventional optical pickup; Fig. 6 is a plan view of Fig. 5 with the cover removed; Fig. 7. is a side view of the lens position sensor in FIG. 5, FIG. 8 is a plan view of the lens position sensor in FIG. 7, and FIG. 9 is a diagram for explaining the problem. In these figures, 1.31...Base 16.46...Lens holder 17.47...Objective lens 57...Reflection plate 57a, 57b...Reflection parts 57c, 57d...Non-reflection Part 58...Photo sensor substrate (sensor) 58a, 58b
... Light emitting element 58C1 58d ... Light receiving element

Claims (1)

[Claims] A lens holder (46) having an objective lens (53);
A base (31) is connected to the lens holder (46) via a supporting means that movably supports the lens holder (46), and directs the laser beam from the light source to the objective lens (53). In an optical pickup that reads and/or writes information by illuminating the recording medium (51) through the lens holder (46), first and second reflecting portions (57a, 57b) are provided on the lens holder (46) side. and the first and second non-reflective parts (
57c, 57d), and has first and second reflective parts (57a
, 57b) and the first and second non-reflective parts (57c, 57d
) are placed diagonally on each other.
57), and first and second light emitting elements (58a, 58) which are provided vertically on the base (31) side and emit a light beam for detecting the lens position of the objective lens (53).
8), and a first light beam provided vertically on the base (31) side and receiving the light beam emitted from the first and second light emitting elements (58a, 58b) and reflected by the reflection plate (57). 1. An optical pickup characterized by having a lens position sensor consisting of a sensor (58) consisting of a second light receiving element (58c, 58d).