JP2003141752A - Optical pickup device and optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the occurrence of offset of a wobble signal by suppressing the deviation between a laser and a collimating lens caused by the temperature change of components. SOLUTION: In the optical pickup device 1 for recording or reproducing the information by converging laser beams on the recording surface of an optical information recording medium, the collimating lens 3 is adhered to a lens mounting hole 15 so that the collimating lens 3 is relatively moved with respect to a center axis 15a of the lens mounting hole 15 to the relatively moving direction of a laser beam outgoing axis 2a of the laser 2 with respect to the center axis 15a of the lens mounting hole 15, at the time of relative displacement accompanied with the temperature change between a housing 10 for holding the laser 2 and a cell 16 for holding the collimating lens 3 by the lens mounting hole 15 while being formed with a material having a linear expansion coefficient different from a linear expansion coefficient of this housing 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device and an optical disc device.

[0002]

2. Description of the Related Art FIG. 9 shows a conventional optical pickup device 100.
Shows the configuration of. The linearly polarized laser beam emitted from the semiconductor laser 101 is converted into a parallel light beam by the collimator lens 102, and is converted into a parallel beam by the beam splitter 103.
The linearly polarized light is converted to circularly polarized light in the optical isolator including the four-wave plate 104. The light converted into the circularly polarized light is condensed by the objective lens 105 and applied to the recording surface Z1 of the optical disc Z, which is an optical information recording medium, in the form of a minute light spot. The reflected light from the optical disc Z follows the reverse path at the time of irradiation, passes through the objective lens 105, and
After it is converted into linearly polarized light whose polarization direction is rotated by 90 ° by the / 4 wavelength plate 104, it reaches the beam splitter 103. Unlike the case of irradiation, this reflected light is reflected by the beam splitter 103, guided toward the first condenser lens 106, and condensed by the second condenser lens 107 in an astigmatic manner. It is incident on the light receiving element 108.

Here, a land and a groove (both not shown) are formed on the optical disc Z for tracking control of a laser beam. Grooves are formed to meander (hereinafter referred to as wobbles) to indicate address information of the optical disc Z.

Further, the light receiving element 108 has a light receiving area A,
It has a structure having B, C, D, E, F, G, H (similar to FIG. 4), and detection signals such as information signals and servo signals based on the output corresponding to the state of the received detection beam are detected. It In particular, the wobble signal Wb is Wb = (A + D)-
It is detected by (B + C).

The size of the light receiving spot of the optical pickup device 100 cannot be increased so much due to the frequency band of the detection signal and the layout space limitation. In addition, it cannot be made too small because of ease of adjustment and deviation with time. Generally, the size of the light-receiving spot is often in the range of several tens of μm to 100 μm.

However, if an attempt is made to obtain a servo signal or a wobble signal from a push-pull signal of a light-receiving spot of this size, the position of the light-receiving spot may be displaced due to the deformation of each part of the optical pickup device 100 due to the temperature change. As a result, an offset of the light-receiving spot occurs, which may cause a problem that a servo signal or a wobble signal cannot be detected.

When there is a single mirror on the forward or backward path of light, the positional deviation of the light receiving spot is most affected by the angular deviation of the mirror. In this case, the optical pickup device 100 may not function depending on the degree of angular deviation of the mirror. However, when the mirror is on the common optical path of the forward and backward paths, the angle error is canceled by the reciprocal movement, so that such a problem does not occur. In order to deal with this problem, as shown in FIG. 9, a beam shaping surface 103a is formed on the beam splitter 103 to eliminate its influence, or even when beam shaping is not performed, the optical path separation surface 103b which is a mirror is It is necessary to devise a parallel reflection surface 103c that is substantially parallel so that the angular relationship between the optical axes of the light source system and the detection system does not change due to the angular deviation of the mirror.

[0008]

As described above, when the inner mirror angle deviation that causes the light receiving spot position deviation is removed, the semiconductor laser 101 has the next effect.
And the position of the collimator lens 102 in the direction orthogonal to the optical axis.

Here, the mounting structure of the semiconductor laser 101 and the collimating lens 102 will be described with reference to FIGS. The semiconductor laser 101 is fixed to the housing 109 of the optical pickup device 100 by crimping. The collimator lens 102 is fitted in the lens mounting hole 111 of the cell 110 with a clearance with a clearance, and the collimating lens 102 is adhered to the lens mounting hole 11 by the adhesive S.
1 is adhered and held. A part of the cell 110 is fixed to the housing 109. Further, as shown in FIG. 11, the collimator lens 102 has a collimator lens 102 in consideration of workability in assembling the cell 110.
Three points are evenly bonded to the lens mounting holes 111 on the entire circumference. Here, the clearance between the lens mounting hole 111 and the collimating lens 102 is set to about 20 μm to 50 μm, and is exaggerated in FIG. 11 for the sake of explanation.

Here, the laser beam emission axis 101a of the semiconductor laser 101 is caused by the deformation of each part due to the temperature change.
The mutual axial position fluctuation allowed between the collimator lens 102 and the central axis 102a of the collimator lens 102 is about several μm, depending on the focal length of the collimator lens and the configuration of the detection system. In clearance fitting with a clearance of about 20 μm to 50 μm in the lens mounting hole 111 of the collimator lens 102, it is not easy to manage the mounting variation to several μm, and the collimator lens 102 is evenly mounted in the lens mounting hole 111. In point bonding, there is a problem in that bonding tends to occur in a state in which one of the three points is biased.

In such a mounting structure, when the temperature changes, each part of the optical pickup device 100 thermally expands or contracts. Generally, the material of the housing 109 is aluminum (Al), magnesium (Mg) or the like. ,
The material of the cell 110 is a hard metal such as copper (Cu) or stainless steel (SUS) in consideration of slippage when adjusting the optical axis. Due to the difference in coefficient of linear expansion between the housing 109 and the cell 110, a semiconductor laser is used. 101 laser beam emission axis 10
1a and the central axis 102a of the collimating lens 102 are misaligned. For example, when the ambient temperature rises, as shown in FIG. 12, a deviation X1 occurs between the laser beam emission axis 101a of the semiconductor laser 101 and the central axis 102a of the collimator lens 102. Thereby, the optical axis 101 of the laser beam emitted from the semiconductor laser 101
A deviation Y1 occurs in b, a positional deviation of the light receiving spot occurs in the detection system including the light receiving element 108, and an offset occurs in the push-pull signal of the light receiving spot. As a result, there arises a problem that the detection signal cannot be accurately detected in the detection system.

A DPP (Differential Push-Pull) method is well known as a means for correcting the offset of the push-pull signal. This is shown in FIG.
As shown in FIG. 2, a grating 112 is arranged in the forward optical path to divide the laser beam into a 0th-order main beam and a ± 1st-order subbeam, and the main beam is a groove (or land), and the subbeams are adjacent lands (or groove). )
Focus on. By this, push-pull of opposite phase is generated between the main and sub, and the push-pull component is substantially added by k (main push-pull) -k (sub push-pull) with k as a coefficient, and the spot shift component is in-phase component. Is to remove it.

The DPP method is an excellent method for correcting a tracking signal, but cannot be applied to offset correction of a wobble signal. This is because when the wobble signal is obtained by this method and an attempt is made to correct the wobble signal, the wobble has a high frequency.
This is because the main spot and the sub-spots at different positions on the optical disk Z pick up different wobble components, and it is not possible to successfully remove only the in-phase components other than the wobble.

An object of the present invention is to suppress the deviation between the laser and the collimator lens due to the temperature change of the parts.

An object of the present invention is to suppress the offset of the wobble signal particularly by suppressing the deviation between the laser and the collimator lens due to the temperature change of the parts.

[0016]

The invention according to claim 1 is
In an optical pickup device for recording or reproducing information by converging a laser beam on a recording surface of an optical information recording medium,
A linear expansion of the housing, which has a housing, a laser which is fixed to the housing and emits a laser beam, a collimator lens that converts the laser beam from the laser into a parallel light flux, and a lens mounting hole that holds the collimator lens. A cell fixed to the housing, the cell being formed of a material having a coefficient of linear expansion different from the coefficient, and the lens mounting hole of the lens when the relative displacement of the housing and the cell due to temperature change occurs. The collimator lens is attached to the lens attachment hole so that the collimator lens moves relatively to the center axis of the lens attachment hole in the relative movement direction of the laser beam emission axis of the laser with respect to the center axis. There is.

Therefore, at the time of relative displacement between the housing and the cell due to temperature change, the central axis of the collimating lens is closer to the laser beam emitting axis side of the laser than the central axis of the lens mounting hole.

According to a second aspect of the invention, in an optical pickup device for recording or reproducing information by condensing a laser beam on a recording surface of an optical information recording medium, a housing and a laser beam fixed to the housing emit a laser beam. Laser, a collimator lens that converts a laser beam from the laser into a parallel light flux, and a lens mounting hole that holds the collimator lens, and a linear expansion coefficient that is the same as or close to a linear expansion coefficient of the housing. And a cell provided in the housing, the cell being formed of a material having

Therefore, even when the housing and the cell thermally expand or contract due to temperature change, the relative positional relationship between the laser and the collimator lens does not change.

According to a third aspect of the present invention, there is provided an optical pickup device for recording or reproducing information by condensing a laser beam on a recording surface of an optical information recording medium, and emitting a laser beam fixed to the housing. Laser, a collimator lens that converts a laser beam from the laser into a parallel light flux, and a mounting surface that holds the collimator lens in a lens mounting hole and is formed along a surface including a central axis of the collimator lens. A cell and a holding surface provided on the housing and formed along a plane including a laser beam emission axis of the laser hold the mounting surface of the cell, and have a coefficient of linear expansion equal to or close to that of the housing. And a cell holding portion formed of a material having a linear expansion coefficient of the above value.

Therefore, even when the housing and the cells are thermally expanded or contracted due to the temperature change, the relative positional relationship between the laser beam emitting axis of the laser and the central axis of the collimating lens does not change.

According to a fourth aspect of the present invention, in the optical pickup device according to the second or third aspect, the collimator lens is adhered to the lens mounting hole around the entire circumference of the collimator lens, or Six or more parts are evenly bonded around the collimator lens.

Therefore, as compared with the conventional uniform three-point bonding, the bonding can be performed more accurately at the center of the lens mounting hole.

The invention of an optical disk device according to claim 5 is
The optical pickup device according to any one of claims 1 to 4 is provided for an optical information recording medium that is rotationally driven.

Therefore, it becomes possible to provide an optical disk device having the same operation as that of the optical pickup device according to any one of claims 1 to 4.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first embodiment of the present invention.
Or, it demonstrates based on FIG. The optical pickup device of the present embodiment is applied to an optical pickup device used in an optical disc device for recording / reproducing information on / from an optical information recording medium.

Here, FIG. 1 is a schematic plan view showing the optical pickup device of the present embodiment, FIG. 2 is a vertical sectional side view showing a mounting structure of a semiconductor laser and a collimator lens, and FIG. The adhesive structure is exaggerated to show
(A) is a front view showing one-point bonding, (b) is a front view showing two-point bonding, (c) is a front view showing three-point bonding, (d) is a front view showing half-round bonding, and FIG. 4 is It is explanatory drawing which shows the division pattern of a light receiving element.

The optical pickup device 1 of the present embodiment is
Semiconductor laser 2 which is a laser for emitting a laser beam
A glass collimating lens 3, a grating 4 for splitting a laser beam into a main beam and two sub-beams, a beam splitter 5, a deflecting prism 6,
It is composed of a quarter-wave plate 7, an objective lens 8, a detection system 9 and the like. Here, the astigmatism method is used for the focus error signal detection in the detection system 9 of the present embodiment, and the DPP (Differential) is used for the track error signal detection.
The Push-Pull (differential push-pull) method is adopted.

Further, as the optical information recording medium of the present embodiment, an optical disk Z in which lands and grooves are formed and the grooves are formed in a wobble is applied. This optical disk is rotated by a rotary drive system (not shown).

The mounting structure of the semiconductor laser 2 and the collimating lens 3 will be described with reference to FIGS. The optical pickup device 1 includes a housing 10.
The housing 10 is formed in an L-shape in which a vertical wall 12 extends toward one surface 13 of the bottom wall 11 at one end of the bottom wall 11. A laser mounting hole 14 for holding the semiconductor laser 2 is formed in the vertical wall 12. And the bottom wall 1
A cylindrical cell 16 having a lens mounting hole 15 for holding the collimating lens 3 is attached to the one surface 13 of the housing 1 with one end 16a facing the central axis 15a of the lens mounting hole 15 being pressed against the one surface 13 of the housing 10. It is screwed by a screw (not shown). The material of the housing 10 of the present embodiment is, for example, aluminum (Al),
The cell 16 is made of a hard metal such as copper (Cu) in consideration of slippage when adjusting the central axis when the cell 16 is attached to the housing 10. Here, the coefficient of linear expansion of copper (Cu) is lower than the coefficient of linear expansion of aluminum (Al).

The semiconductor laser 2 is fixed to the laser mounting hole 14 of the vertical wall 12 by caulking.

The collimator lens 3 is attached to the lens mounting hole 15 of the cell 16 by being adhered to the lens mounting hole 15 in a state of being fitted in a clearance with a clearance. At this time, the collimating lens 3 is moved relative to the central axis 15a of the lens mounting hole 15 in the relative movement direction of the laser beam emitting axis 2a of the laser 2 when the housing 10 and the cell 16 are displaced relative to each other due to the temperature change. 15
The lens mounting hole 15 is adhered and mounted so as to move relative to the central axis 15a. More specifically, as shown in FIG. 3A, the collimator lens 3 utilizes the clearance between the cell 16 and the other end 1 which is the side opposite to the one end 16 a side of the cell 16 of the lens mounting hole 15.
It is moved to the side of 6b and is bonded at one place by the adhesive S there. At this time, the central axis of the collimator lens 3 coincides with the central axis of the semiconductor laser 2. Here, the clearance between the lens mounting hole 15 and the collimating lens 3 is
The thickness is about 20 μm to 50 μm, and is exaggerated in FIG. 3 for the sake of explanation. The direction W1 (see FIG. 2) in which the wobble signal offset is generated by the relative displacement between the semiconductor laser 2 and the collimator lens 3 is the opposite direction between the one end 16a side and the other end 16b side of the cell 16.

The bonding structure of the collimator lens 3 to the cell 16 is not limited to the one-point bonding as described above, but the lens may be moved when the housing 10 and the cell 16 are displaced relative to each other due to a temperature change. Center axis 1 of mounting hole 15
It may be attached to the lens mounting hole 15 so as to move relative to the central axis 15a of the lens mounting hole 15 in the relative movement direction of the laser beam emitting axis 2a of the laser 2 with respect to 5a. For example, as shown in FIG. 3 (b), the lens mounting hole 15 is evenly bonded at two points within the half circumference of the cell 16 on the side of the other end 16 b of the cell 16, and as shown in FIG. In the half circumference of the cell 16 on the side of the other end 16b of the cell 15, the adhesive S may be used to bond three or more evenly or three or more evenly. Furthermore, the lens mounting hole 1 as shown in FIG.
5 may be a semi-circular adhesion in which the entire range is adhered by the adhesive S within the semi-circumference on the other end 16b side of the cell 16.
These may be appropriately selected in view of impact resistance, strength, and required accuracy.

As shown in FIG. 1, the beam splitter 5 has a laser beam incident surface 5a having a function as a beam shaping surface and an internal reflection surface 5b. The internal reflection surface 5b and the optical path separation surface 5c that separates the outward path and the return path of the laser beam are set substantially parallel to each other, and the push-pull signal in the detection system 9 is offset by the angle change of the beam splitter 5 due to temperature change or the like. Has been prevented.

The detection system 9 is composed of a first condenser lens 17, a second condenser lens 18 having an astigmatism generating function, a light receiving element 19 having a light receiving region of 8 divisions, and the like. .

As shown in FIG. 4, the light-receiving element 19 receives the divided light receiving areas A, B, C and D for receiving the reflected light component concerning the main beam and the reflected light component concerning one sub-beam. The light receiving areas E and F are divided into two areas, and the light receiving areas G and H are divided into two areas for receiving the reflected light component relating to the other sub-beam.
The light receiving element 19 detects the received laser beam as an electric signal, and includes a focus error signal FE and a tracking error signal T which are information signals and servo signals.
Detection signals such as E and wobble signal Wb are detected.

Here, the focus error signal FE is FE = (A + C)-(B + D) It is said that

The tracking error signal TE has a constant k.
Then, TE = {(A + D)-(B + C)}-k {(F + H)-
(E + G)}.

The wobble signal Wb is Wb = (A + D)-(B + C). Here, W2 in FIG. 4 indicates the offset direction of the wobble signal Wb.

In such a structure, the semiconductor laser 2
The linearly polarized laser beam emitted from is converted into a parallel light beam by the collimator lens 3, and is converted from linearly polarized light into circularly polarized light in the optical isolator including the beam splitter 5 and the quarter wavelength plate 7. The light converted into circularly polarized light is condensed by the objective lens 8 and is applied to the recording surface Z1 of the optical disc Z in the form of a minute light spot. The reflected light from the optical disk Z follows the reverse path at the time of irradiation, passes through the objective lens 8, is converted by the quarter-wave plate 7 into linearly polarized light whose polarization direction is rotated by 90 °, and then is reflected by the beam splitter 5. To reach. Unlike the case of irradiation, this reflected light is reflected by the beam splitter 5, guided to the direction of the condenser lens 17, condensed by the condenser lens 18 in the form of astigmatism, and incident on the light receiving element 19. It Then, the light receiving element 19 detects the information signal, the focus error signal, the tracking error signal, and the wobble signal.

Here, the temperature rises and the housing 10
Laser 2 when the cell 16 and the cell 16 are thermally expanded and deformed
The relative positional relationship between the collimator lens 3 and the collimator lens 3 will be described with reference to FIG.

As the temperature rises, the housing 10 and the cell 1
When 6 and 6 thermally expand, the linear expansion coefficient of the housing 10 is higher than the linear expansion coefficient of the cell 16, so that the housing 10 expands more than the cell 16. This allows
A relative displacement occurs between the laser mounting hole 14 and the lens mounting hole 15. At this time, the semiconductor laser 2 has the housing 1
Since it is attached by crimping to 0, it is displaced together with the laser attachment hole 14. As a result, the laser beam emission axis 2a is displaced relative to the lens mounting hole 15, and the laser beam emission axis 2a of the semiconductor laser 2 is
The cell 16 is located in the direction from the central axis 15a of the lens mounting hole 15 of the cell 16 toward the other end 16b of the cell 16 fixed to the housing 10 in the lens mounting hole 15.

On the other hand, the collimator lens 3 is moved to the other end 16b side of the cell 16 and bonded at one position there. Further, since the linear expansion coefficient of glass is lower than the linear expansion coefficient of metal, the lens mounting hole 15 is provided. When is expanded, it will be positioned in a state of being biased to the adhesion portion of the lens mounting hole 15, that is, the other end 16b side of the cell 16 in the lens mounting hole 15. That is, the central axis 3a of the collimator lens 3 is located closer to the laser beam emitting axis 2a of the semiconductor laser 2 held in the laser mounting hole 14 than the central axis 15a of the lens mounting hole 15. become. As a result, the deviation X2 in the relative positional relationship between the semiconductor laser 2 and the collimator lens 3 due to the difference in the linear expansion coefficient between the housing 10 and the cell 16 due to the temperature change can be suppressed to a small value, and the semiconductor laser 2 emits the light. The deviation Y2 of the optical axis 2b of the laser beam can be reduced,
As a result, the positional deviation of the light receiving spot in the detection system 9 can be suppressed. Therefore, in the detection system 9, it is possible to suppress the occurrence of the offset of the wobble signal that cannot be corrected even by the servo signal or especially the DPP method, or the optical pickup device 1 as described above.
It is possible to provide an optical disk device equipped with.

In this embodiment, the housing 10
However, the material of the cell is not limited to this, and the coefficient of linear expansion of the material of the cell may be equal to or lower than the coefficient of linear expansion of the material of the housing.

Next, although not shown, a modification will be described. In the above-described embodiment, an example in which the linear expansion coefficient of the material of the cell 16 is less than or equal to the linear expansion coefficient of the material of the housing 10 has been described. In this example, the linear expansion coefficient of the material of the cell 16 is equal to that of the housing 10. This is an example when the coefficient of linear expansion of the material is equal to or higher than that. In this case, the configuration of the optical pickup device 1 is basically the same. The difference from the above embodiment is the mounting structure of the cell 16 of the collimator lens 3 in the lens mounting hole 15. Specifically, the collimator lens 3 is attached by being attached to the lens attachment hole 15 within the half circumference of the lens attachment hole 15 on the side of the one end 16 a. The number of adhesion points is the same as in the above-mentioned embodiment.

As the temperature rises, the housing 10 and the cell 1
When 6 and 6 thermally expand, the coefficient of linear expansion of the cell 16 is higher than that of the housing 10, so that the cell 16 expands more than the housing 10. This allows
A relative displacement occurs between the laser mounting hole 14 and the lens mounting hole 15. At this time, the semiconductor laser 2 has the housing 1
Since it is attached by crimping to 0, it is displaced together with the laser attachment hole 14. As a result, the laser beam emission axis 2a is displaced relative to the lens mounting hole 15, and the laser beam emission axis 2a of the semiconductor laser 2 is
The cell 16 is located in the direction from the central axis 15a of the lens mounting hole 15 of the cell 16 toward the one end 16a of the cell 16 fixed to the housing 10 in the lens mounting hole 15.

On the other hand, the collimator lens 3 is moved to the other end 16b side of the cell 16 and bonded at one position there, and since the linear expansion coefficient of glass is lower than the linear expansion coefficient of metal, the lens mounting hole 15 When is expanded, it is located in a state of being biased to the lens attachment hole 15, that is, the adhesion portion thereof, that is, the one end 16a side of the cell 16 in the lens attachment hole 15. That is, the central axis 3a of the collimator lens 3 is located closer to the laser beam emitting axis 2a of the semiconductor laser 2 held in the laser mounting hole 14 than the central axis 15a of the lens mounting hole 15. become. As a result, it is possible to suppress the deviation of the relative positional relationship between the semiconductor laser 2 and the collimator lens 3 due to the difference in the linear expansion coefficient between the housing 10 and the cell 16 due to the temperature change, so that the semiconductor laser 2 emits light. The deviation of the optical axis 2b of the laser beam can be reduced, and as a result, the positional deviation of the light receiving spot in the detection system 9 can be suppressed. Therefore, it is possible to provide an optical pickup device 1 or an optical disc device equipped with such an optical pickup device 1 capable of suppressing the occurrence of an offset of a wobble signal that cannot be corrected by a servo signal or a DPP method in the detection system 9. You can

Next, a second embodiment of the present invention will be described with reference to FIG. 6A and 6B are exaggeratedly showing the bonding structure of the collimator lens of the present embodiment to the cell, FIG. 6A is a front view showing six-point bonding, and FIG. 6B is a front view showing all-round bonding. The same parts as those described in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted (same in the following embodiments). The basic structure of this embodiment is the same as that of the first embodiment, and the difference from the first embodiment is that the coefficient of linear expansion of the material of the cell 21 is the housing 10.
It is the same as or close to the linear expansion coefficient of the material. Specifically, the material of the cell is, for example, aluminum (Al) or the like. Due to this difference, the attachment structure of the collimator lens 3 to the cell 21 is also different from that of the first embodiment.

The structure for attaching the collimator lens 3 to the cell 21 will be described. As shown in FIG. 6A, the collimator lens 3 is arranged in the center of the lens mounting hole 15 with a uniform clearance with respect to the lens mounting hole 15 of the cell 21, and is evenly distributed over the entire circumference by the adhesive S. It is fixed by adhesion at 6 points. At this time, the collimator lens 3
The central axis of is coincident with the central axis of the semiconductor laser 2.
In addition, although the bonding structure has been described as being evenly bonded at six points, it is not limited to this, and it is sufficient if it is at least six points. Furthermore, the lens mounting hole 1 as shown in FIG.
All around 5 may be bonded. In the conventional uniform three-point bonding, it is difficult to bond the collimating lens 3 and the cell 21 with a uniform clearance over the entire circumference of the collimating lens 3, and it is easy to bond in a state biased to one of the three points. However, the above-mentioned even 6-point bonding and full-circumferential bonding have more bonding points than the uniform 3-point bonding, and thus have excellent uniformity,
The clearance between the collimator lens 3 and the cell 21 becomes more uniform over the entire circumference of the collimator lens 3.

In such a structure, when the temperature rises and the housing 10 and the cell 21 are thermally expanded and deformed, the linear expansion coefficients of the housing 10 and the cell 21 are the same or close to each other. The laser beam emission axis 2a of the semiconductor laser 2 which is displaced together with the laser attachment hole 14 by being attached by the and the central axis 15a of the lens attachment hole 15 of the cell 21 do not move relatively or even if they move. It is a very short distance. Since the collimator lens 3 is evenly attached to the center of the lens attachment hole 15 with respect to the cell 21 over the entire circumference thereof, the lens of the cell 21 is deformed even when the cell 21 is thermally expanded and deformed. The positional relationship between the central axis 15a of the mounting hole 15 and the collimator lens 3 does not change, or is small even if it changes. As a result, it is possible to eliminate or reduce the deviation of the relative positional relationship between the semiconductor laser 2 and the collimator lens 3 due to the temperature change, and it is possible to prevent or suppress the deviation of the optical axis of the laser beam emitted from the semiconductor laser 2. Therefore, the positional deviation of the light receiving spot in the detection system 9 can be suppressed. As a result, it is possible to provide an optical pickup device capable of suppressing the occurrence of an offset of a wobble signal which cannot be corrected by the servo signal or particularly the DPP method in the detection system 9 or an optical disc device equipped with such an optical pickup device. it can.

Next, a third embodiment of the present invention will be described with reference to FIGS. FIG. 7 is a side view showing the mounting structure of the semiconductor laser and the collimator lens according to the present embodiment, and FIG. 8 is an exploded perspective view showing the mounting structure of the collimator lens. The basic structure of the present embodiment is the same as that of the first embodiment, and the difference from the first embodiment is that
The shapes of the cell 31 and the housing 32 are different from each other, and the attachment structure of the cell 31 to the housing 32 is different.

The cell 31 is provided with mounting portions 33 having mounting surfaces 33a formed along the surface including the central axis 15a of the lens mounting hole 15 or a surface in the vicinity thereof, on both sides.

The housing 32 has a laser beam emitting shaft 2 for the semiconductor laser 2 held in the laser mounting hole 14.
A pair of holding portions 34 having a holding surface 34a formed along a plane including a or a surface in the vicinity thereof is formed to extend from one surface 13 of the bottom wall 11. This holding portion 34
The housing 32 is formed of a material having a linear expansion coefficient that is the same as or close to the linear expansion coefficient of the material of the housing 32.

In the cell 31, the mounting portion 33 is fixed to the housing 32 by screwing the mounting portion 33 to the holding portion 34 of the housing 32 with the mounting surface 33a of the cell 31 in contact with the holding surface 34a of the housing 32. Has been done.
At this time, the linear expansion coefficients of the materials of the housing 10 and the cells 16 may be the same or different.

As described in the second embodiment, the collimator lens 3 is adhered to the cell 31 at six or more points uniformly, or is adhered all around. At this time, the central axis of the collimator lens 3 coincides with the central axis of the semiconductor laser 2.

In such a structure, when the temperature rises and the housing 32 and the cell 31 are thermally expanded and deformed, the holding surface 34a of the housing 32 is held in the laser attachment hole 14 by the semiconductor. Since it is displaced in the same manner as the laser beam emitting axis 2a of the laser 2, the laser mounting hole 1
There is no change in the relative positional relationship between the laser beam emitting axis 2a of the semiconductor laser 2 held by the No. 4 and the holding surface 34a. As a result, the central axis 15a of the lens mounting hole 15 of the cell 31 does not change in the relative positional relationship with respect to the laser beam emitting axis 2a of the semiconductor laser 2 held in the laser mounting hole 14. Therefore, the positional relationship between the laser beam emission axis 2a of the semiconductor laser 2 and the central axis 3a of the collimator lens 3 does not change relatively. As a result, it is possible to suppress the deviation of the relative positional relationship between the semiconductor laser 2 and the collimator lens 3 due to the temperature change of the parts, and to suppress the deviation of the optical axis of the laser beam emitted from the semiconductor laser 2. Therefore, the positional deviation of the light receiving spot in the detection system 9 can be suppressed. Therefore, it is possible to provide an optical pickup device capable of suppressing the occurrence of a wobble signal offset that cannot be corrected by the servo signal or particularly the DPP method in the detection system 9, or an optical disc device equipped with such an optical pickup device. .

[0057]

According to the first aspect of the invention, in an optical pickup device for recording or reproducing information by converging a laser beam on a recording surface of an optical information recording medium, the housing is fixed to the housing. A laser that emits a laser beam, a collimator lens that converts the laser beam from the laser into a parallel light beam, and a lens mounting hole that holds the collimator lens are provided, and a linear expansion coefficient different from the linear expansion coefficient of the housing is set. Formed of material having
A cell fixed to the housing, and a relative movement direction of a laser beam emitting axis of the laser with respect to a central axis of the lens mounting hole when the housing and the cell are relatively displaced due to a temperature change. Since the collimator lens is attached to the lens attachment hole so that the collimator lens moves relatively to the central axis of the lens attachment hole, the relative movement of the housing and the cell due to temperature change. At the time of displacement, the central axis of the collimator lens is closer to the laser beam emission axis side of the laser than the central axis of the lens mounting hole. Therefore, as compared with the conventional optical pickup device in which the periphery of the collimator lens is evenly attached and attached to the lens attachment hole, the deviation between the laser and the collimator lens due to the temperature change of the component can be suppressed. As a result, it is possible to suppress the occurrence of offset of the wobble signal.

According to the second aspect of the invention, in an optical pickup device for recording or reproducing information by converging a laser beam on a recording surface of an optical information recording medium, a housing and a laser beam fixed to the housing. A laser that emits, a collimator lens that converts a laser beam from the laser into a parallel light flux, and a lens mounting hole that holds the collimator lens, and a line having a value that is the same as or close to the linear expansion coefficient of the housing. By providing a cell formed of a material having an expansion coefficient and provided in the housing, the relative positional relationship between the laser and the collimating lens even when the housing and the cell thermally expand or contract due to temperature change. Since it does not change, it is possible to suppress the deviation between the laser and the collimator lens due to the temperature change of the parts. Kill. As a result, it is possible to suppress the occurrence of offset of the wobble signal.

According to the invention described in claim 3, in an optical pickup device for recording or reproducing information by condensing a laser beam on a recording surface of an optical information recording medium, a housing and a laser beam fixed to the housing. A laser emitting light, a collimating lens for converting a laser beam from the laser into a parallel light flux, and a collimating lens held by a lens mounting hole, and a mounting surface formed along a surface including a central axis of the collimating lens. And a holding surface that is provided in the housing and that is formed along a plane that includes the laser beam emission axis of the laser, holds the mounting surface of the cell and is the same as the linear expansion coefficient of the housing. Alternatively, by including a cell holding part formed of a material having a linear expansion coefficient of an approximate value, Even if the cell and the cell thermally expand or contract, the relative positional relationship between the laser beam emission axis of the laser and the central axis of the collimator lens does not change, so that the laser and the collimator lens are caused by the temperature change of the parts. Displacement can be suppressed. As a result, it is possible to suppress the occurrence of offset of the wobble signal.

According to a fourth aspect of the invention, in the optical pickup device according to the second or third aspect, is the collimator lens adhered to the lens mounting hole around the entire circumference of the collimator lens? Alternatively, by bonding six or more points evenly around the collimating lens, it is possible to more accurately bond the lens to the center of the lens mounting hole as compared with the conventional uniform three-point bonding. It is possible to prevent the collimator lens from shifting from the center of the lens mounting hole even when expanded, and it is possible to suppress the deviation between the laser and the collimator lens due to the temperature change of the components. This allows
It is possible to suppress the occurrence of offset of the wobble signal.

According to the invention of the optical disk device described in claim 5, the optical information recording medium which is rotationally driven is defined by claim 1.
By including the optical pickup device according to any one of claims 1 to 4, it is possible to provide an optical disk device having the same operation and effect as the optical pickup device according to any one of claims 1 to 4.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing an optical pickup device according to a first embodiment of the present invention.

FIG. 2 is a vertical sectional side view showing a mounting structure of a semiconductor laser and a collimator lens.

FIG. 3 is an exaggerated view of a structure for bonding a collimator lens to a cell, where (a) is a front view showing one-point bonding, (b) is a front view showing two-point bonding, and (c) is three-point bonding. Front view,
(D) is a front view showing half-circle bonding.

FIG. 4 is an explanatory diagram showing a division pattern of a light receiving element.

FIG. 5 is a vertical cross-sectional side view schematically showing a positional shift relationship between a semiconductor laser and a collimator lens due to thermal expansion deformation of a housing and a cell.

6A and 6B are exaggeratedly showing a bonding structure of a collimator lens according to a second embodiment of the present invention to a cell, FIG. 6A is a front view showing six-point bonding, and FIG. 6B is a front view showing all-round bonding. It is a figure.

FIG. 7 is a side view showing a mounting structure of a semiconductor laser and a collimator lens according to a third embodiment of the present invention.

FIG. 8 is an exploded perspective view showing a mounting structure of a collimator lens.

FIG. 9 is a schematic plan view showing a conventional optical pickup device.

FIG. 10 is a vertical sectional side view showing a mounting structure of a semiconductor laser and a collimator lens.

FIG. 11 is a front view exaggeratingly showing a bonding structure of a collimator lens to a cell.

FIG. 12 is a vertical cross-sectional side view schematically showing a positional shift relationship between a semiconductor laser and a collimator lens due to thermal expansion deformation of a housing and a cell.

[Explanation of symbols]

1 Optical pickup device 2 laser (semiconductor laser) 2a Laser beam emission axis 3 Collimating lens 10,32 housing 15 Lens mounting hole 15a central axis 16,21,31 cells 33a Mounting surface 34 Cell holding unit 34a holding surface Z optical information recording medium (optical disk) Z1 recording surface

Claims (5)

[Claims] 1. An optical pickup device for recording or reproducing information by condensing a laser beam on a recording surface of an optical information recording medium, a housing, a laser fixed to the housing and emitting a laser beam, and the laser. A collimator lens for converting the laser beam from the light beam into a parallel light flux, and a lens mounting hole for holding the collimator lens,
A cell formed of a material having a linear expansion coefficient different from the linear expansion coefficient of the housing, the cell being fixed to the housing, wherein the relative displacement of the housing and the cell due to temperature change, The collimator lens is attached to the lens attachment hole so that the collimator lens moves relative to the center axis of the lens attachment hole in the relative movement direction of the laser beam emission axis of the laser with respect to the center axis of the lens attachment hole. An optical pickup device characterized in that it is attached to. 2. An optical pickup device for recording or reproducing information by condensing a laser beam on a recording surface of an optical information recording medium, a housing, a laser fixed to the housing and emitting a laser beam, and the laser. A collimator lens for converting the laser beam from the light beam into a parallel light flux, and a lens mounting hole for holding the collimator lens,
An optical pickup device comprising: a cell formed of a material having a coefficient of linear expansion that is the same as or close to a coefficient of linear expansion of the housing and provided in the housing. 3. An optical pickup device for recording or reproducing information by converging a laser beam on a recording surface of an optical information recording medium, a housing, a laser fixed to the housing and emitting a laser beam, and the laser. A collimator lens for converting the laser beam from the light beam into a parallel light flux, a cell having a mounting surface formed along a surface including the central axis of the collimator lens, the collimator lens being held by a lens mounting hole; A holding surface formed along a plane including the laser beam emitting axis of the laser holds the mounting surface of the cell and has a linear expansion coefficient that is the same as or close to the linear expansion coefficient of the housing. An optical pickup device, comprising: a cell holding part formed of a material having 4. The collimator lens is adhered to the lens mounting hole around the entire circumference of the collimator lens, or is evenly adhered to six or more places around the collimator lens. The optical pickup device according to claim 2 or 3. 5. An optical disk device comprising the optical pickup device according to claim 1 for a rotationally driven optical information recording medium.