JP2006302367A - Optical pickup, adjusting method and optical information processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide optical components and an optical pickup capable of suppressing an aberration of a spot condensed by an objective lens without a mechanical adjusting mechanism, and to provide the adjusting method. <P>SOLUTION: Such a point is different from conventional practice that the lens consisting of a solid lens and a liquid lens is used as a collimating lens 2002. The optical components are constituted of a semiconductor laser 2001, the collimating lens 2002 for converting a radiant light beam radiated from the semiconductor laser 2001 to parallel luminous flux, a triangular beam shaping prism 2003, a polarizing beam splitter 2004, a 1/4 wavelength plate 2005, a deflection mirror 2006, the objective lens 2007, an optical recording medium 2008, a detection lens 2029, and a photodetector 2010. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical pickup, an adjustment method, and an optical information processing apparatus, and more particularly to an optical pickup that uses a liquid lens to facilitate adjustment of each lens and an adjustment method thereof.

An optical pickup that records or reproduces information on an optical recording medium is equipped with a semiconductor laser, a collimating lens, an objective lens, a light receiving element, and the like, and high precision is required when adjusting and assembling these components. . For this reason, as for the semiconductor laser, for example, an adjustment mechanism for adjusting the position of the semiconductor laser as shown in Patent Document 1 and Patent Document 2 has been proposed. Alternatively, as for the collimating lens, a lens cell for adjusting the position of the collimating lens as shown in Patent Document 3 and its adjustment mechanism have been proposed. For the objective lens, an adjustment mechanism as shown in Patent Document 4 has been proposed. If fine adjustment by the various adjustment mechanisms as described above is not performed, astigmatism and coma aberration occur in the spot condensed by the objective lens, and recording on the optical recording medium cannot be performed. Such as inability to read the information signal.
FIG. 26 is a block diagram showing the configuration of a conventional optical pickup device. The optical pickup device 100 is configured by mounting various optical components on a housing 1030 made of aluminum, magnesium, or the like. Some optical components are installed on the housing 1030 in a state of being fixed to members such as a holder and a cell. The holder and the cell are for adjusting the position of the optical component, and are formed with holes and the like so that they can be moved by an assembly jig.
As optical components, there are a semiconductor laser 1001, a collimating lens 1002 for converting radiated light emitted from the semiconductor laser 1001 into a parallel light beam, a triangular beam shaping prism 1003, a polarizing beam splitter 1004, and a quarter. A wave plate 1005, a deflection mirror 1006, an objective lens 1007, an optical recording medium 1008, a detection lens 1009, and a light receiving element 1010 are included.
The emitted light of the semiconductor laser 1001 is converted into a parallel light beam by the collimator lens 1002 and then enters the beam shaping prism. In general, since the emitted light of a semiconductor laser has a horizontal radiation angle narrower than a vertical radiation angle, a cross section perpendicular to the optical axis of parallel light is elliptical. Therefore, by expanding the horizontal beam of parallel light by the shaping prism 1003 having a triangular prism shape, a cross section perpendicular to the optical axis of the elliptical parallel light approaches a circle. Then, the light passes through the polarizing beam splitter 1004, passes through the quarter-wave plate 1005, becomes circularly polarized light, is deflected by 90 ° to the deflecting mirror 1006, enters the objective lens 1007, and is collected as a minute spot on the optical recording medium 1008. Shined. Information is reproduced, recorded or erased by this spot. On the other hand, the light reflected from the optical recording medium 1008 becomes circularly polarized light in the opposite direction to the outward path, is again made substantially parallel light, passes through the wave plate 1005, becomes linearly polarized light orthogonal to the forward path, and is reflected by the polarizing beam splitter 1004. Then, the light is converged by the detection lens 1009 and reaches the light receiving element 1010 having a plurality of light receiving segments. An information signal and a servo signal are detected from the light receiving element 1010.

Next, various mechanisms for adjusting the assembly of the conventional optical pickup device will be described. The components mounted on the optical pickup are required to be assembled with high accuracy in order to reproduce or write information from the optical recording medium. Hereinafter, the assembly procedure will be described with reference to the assembly flow of FIGS.
First, the beam shaping prism 1003, the polarization beam splitter 1004, the quarter wavelength plate 1005, and the deflection mirror 1006 are bonded and fixed to the housing 1030 (step 101). These are provided with positioning references on the housing 1030, and are fixedly bonded in accordance with these references. Next, the semiconductor laser 1001 is bonded and fixed to the semiconductor laser holder 1011a (step 102), and the collimating lens 1002 is bonded and fixed to the lens cell 1012a (step 104). Then, the holder 1011a and the cell 1012a are temporarily fixed to the housing 1030 (steps 103 and 105). Similarly, the light receiving element 1010 is bonded and fixed to the light receiving element holder 1015a (step 108), and the detection lens 1009 is bonded and fixed to the lens cell 1014a (step 106). Then, the holder 1015a and the cell 1014a are temporarily fixed to the housing 1030 (steps 107 and 109).
The holders 1011a and 1015a are bonded to the semiconductor laser 1001 and the light receiving element 1010 in the plane perpendicular to the optical axis, and a plate-like member has a window in which the laser 1001 and the light receiving element are inserted. Fixed in state. Further, each holder is provided with holes 1011b, c, 1015b, c. This is because the tip of the assembling jig is inserted into this hole and the holder is moved relative to the housing 1030 in the plane perpendicular to the optical axis. Use to let them. The lens cells 1012a and 1014a are cylindrical lens holding members extending in the optical axis direction. The lens cells 1012a and 1014a are held so that the outer periphery of the lens is inscribed in the cell, and are integrally formed as a single component. Further, each cell is provided with holes 1012b and 1014b, which are inserted into the hole by an assembling jig, for example, an eccentric pin, to move the cell relative to the housing 1030 in the optical axis direction. To use.

FIG. 28 is a diagram showing a package configuration example using a semiconductor laser as a general laser light source and the state of laser light. A laser chip 2 of the semiconductor laser 1 is mounted on a base 3 and sealed with a cap 4 with a window glass. The position of the light emitting point 26 of the laser chip 2 has a variation up to about 80 μm with respect to the center line 35 of the base 3. Now, such a positional shift of the light emitting point is a shift with respect to the optical axis of the collimating lens 1002, and the beam after passing through the collimating lens 1002 travels at an angle shifted with respect to the optical axis of the collimating lens. Now, it is known that when a beam having such a shifted inclination is incident on the objective lens, an aberration as shown in FIG. 29 occurs. That is, FIG. 29 shows the relationship between image height and wavefront aberration, but it is generally known that coma and astigmatism increase as the image height increases. It is known that when there is coma or astigmatism, a spot image condensed on the optical recording medium is deteriorated. Therefore, by adjusting the optical axes of the collimator lens and the semiconductor laser, for example, when the lower surface of the housing in FIG. 26 is used as the reference surface of the pickup, the rising light is adjusted to be substantially perpendicular to the reference surface. (Step 110).
Specifically, an installation surface of a jig (not shown) for installing the housing 1030 is observed with an autoremeter (not shown) or the like, and then the housing 1030 is installed, the semiconductor laser is turned on, and the deflection mirror is used. It is possible to ensure vertical rising light by making it coincide with the installation surface while observing the rising light with auto collimation. With the vertical rising light secured, the holder 1011a is fixed to the housing 1030 by screws or adhesion.
Regarding the movement of the semiconductor laser 1001, holes 1011b and c are provided on the semiconductor laser holder 1011a, and the tip of the two rod-shaped members serving as the semiconductor laser adjusting arm 1021a is a V-shaped tip. What is necessary is just to insert the nail | claw which has a surface and to move a holder within XY plane.

Subsequently, adjustment is performed to cause the semiconductor laser 1001 to emit light and to remove astigmatism of the laser light that has passed through the collimator lens 1002. In general, the emitted light of a semiconductor laser has an astigmatic difference that the light emitting point position is shifted between the horizontal direction and the vertical direction. The light emitting point position in the vertical direction is almost at the laser emitting end face, but the light emitting point position in the horizontal direction is often moved inward from the emitting end face in units of several μm to several tens of μm. For this reason, when the emitted light is collected, astigmatism occurs also at the condensing point, and it becomes difficult to form a minute spot. On the other hand, the beam shaping prism 1003 causes astigmatism in transmitted light when incident light deviates from parallel light and becomes convergent light or divergent light. For this reason, in the optical pickup configured as shown in FIG. 26, the interval between the collimating lens 1002 and the semiconductor laser 1001 is changed to shift the incident light to the shaping prism from the parallel light, thereby canceling the astigmatism of the objective lens incident beam. Corrections have been made.
The housing 1030 is provided with a reference mounting surface so that the lens cell 1012a for the collimating lens moves along the optical axis. The position of the collimating lens 1002 in the optical axis direction is adjusted and bonded and fixed so that the laser light emitted from the semiconductor laser 1001 and the laser light passing through the collimating lens 1002 becomes parallel light (step 111). Specifically, it is only necessary to use an autocollimator (not shown) used for the laser emission light adjustment described above so that the parallel light is obtained while observing the rising light from the deflection mirror. Alternatively, a wavefront aberration measuring interferometer or the like may be arranged instead of the autocollimator. Then, the cell 1012a may be bonded or screwed through a leaf spring in a state adjusted to minimize astigmatism.
For the movement of the collimating lens 1002, a hole 1012b is provided on the lens cell 1012a, an eccentric pin 1022 is inserted as a cell adjustment arm on the hole, and the pin is rotated while being pressed against the housing 1030. Then, the cell 1012a moves in the optical axis direction.
The adjustment of the semiconductor laser and the collimating lens may not be performed once serially, but the semiconductor laser and the collimating lens may be fixed after each step is repeated.
Next, the objective lens 1007 is bonded and fixed at a position where an opening for passing the optical path of the actuator is formed (step 112). And what was temporarily assembled with 1013a which is a support base of an actuator is temporarily installed on a housing (process 113, 114).

From FIG. 28, the laser chip 2 of the semiconductor laser 1 is mounted on the base 3 and sealed with a cap 4 with a window glass. The emission direction (intensity distribution center) 6 of the laser light 5 emitted from the laser chip 2 has a variation of about 3 ° with respect to the perpendicular of the base 3. As a result, the light quantity of the semiconductor laser is shifted from the optical axis. In FIG. 26, if the emission direction (intensity distribution center) of the semiconductor laser 1001 is deviated from the common optical axis of the objective lens 1007 and the collimator lens 1006, the intensity distribution of the laser light reaching the light receiving element 1010 is deviated. In addition, problems such as the occurrence of an offset in an output signal, particularly a track shift signal or a focus shift signal that uses a change in light intensity distribution in the light receiving element 1010, are likely to occur. For this reason, it is desired to adjust the emission direction (intensity distribution center) to coincide with the optical axis of the objective lens.
Specifically, after the objective lens support base 1013a is temporarily installed on the housing, the objective lens is moved relative to the housing 1030 in the plane perpendicular to the optical axis while holding the support base 1013a with an arm (not shown). What is necessary is just to search for the position where the light quantity distribution of the transmitted light is maximized or the position where the balance of the light quantity distribution is equal. At that position, the support base 1013a may be bonded to the housing (step 115).
FIG. 30 is a schematic perspective view of the actuator 1013b and the support base 1013a. A hole 55 is provided in the actuator 1013b. The hole portions 55 are provided for inserting angle adjusting screws 11 to be described later. The positions of the hole portions 55 are, for example, the positions of the respective hole portions 55 at the center point of the opening portion 27 of the actuator 1013b. It is made to be the vertex of an equilateral triangle in the center. A spherical washer 6 is attached to the actuator 1013b as will be described later. In the optical pickup, the hole 55 is provided as described above, whereby the actuator 1013b and the support base 1013a are fixed by the angle adjusting screw 11 at three points.
The spherical washer 6 is a ring-shaped metal having an opening 28 having a diameter equivalent to that of the opening 26 of the bobbin 23 at the center, and has an attachment reference surface 49 that is a part of a spherical surface. The spherical washer 6 is positioned and fixed so that the center of the opening 28 coincides with the center of the opening 26 of the actuator 1013b. This fixing is, for example, by adhesion.

Next, the support base 1013 a has an opening 29, a mounting reference surface 48, and a screw hole 56. The opening 29 has a diameter equivalent to that of the laser beam incident from below vertically. The mounting reference surface 48 is formed by a concave portion having the same spherical surface as the mounting reference surface 49 of the spherical washer 6, and the mounting reference surface 49 of the spherical washer 6 that is convex by this and the mounting reference surface 48 that is concave are formed. To be matched. The screw hole 56 is provided for screwing the angle adjusting screw 11, and the actuator 1013 b is attached to the support base 1013 a and the mounting reference surface 49 of the spherical washer 6 and the support base as described above. When placed in contact with the reference mounting surface 48 of 1013a, the position corresponds to the hole 55 described above.
The actuator 1013b and the support base 1013a configured as described above are attached by the angle adjusting screw 11 as shown in FIG. As shown in the figure, the angle adjusting screw 11 is inserted into the hole 55 of the actuator 1013b, and then screwed into the screw hole 56 of the support base 1013a in a state where the spring 70 is inserted on the lower surface side of the actuator 1013b.
As described above, by changing the tightening degree of each of the three angle adjusting screws 11, the mounting reference surface 49 of the spherical washer 6 is supported within the spherical surface centered on the principal point of the objective lens 1007, for example. It slides on the mounting reference surface 48 of the base 1013a, and the inclination angle of the actuator 1013b with respect to the support base 1013a can be adjusted. The position where the angle adjusting screw is screwed is the position of the hole 55 of the actuator 1013b described above, that is, the apex of an equilateral triangle centering on the center point of the openings 26 and 29. By adjusting the screws, the tilt angle between the actuator 1013b and the support base 1013a can be freely adjusted in any direction. And the inclination of the actuator 1013b and the support base 1013a can be adjusted by adjusting the angle adjusting screw 11 in this way.

Further, it is known that the objective lens 1007 itself has an aberration. Among them, the coma aberration component can be canceled by tilting the objective lens with respect to the incident optical axis. For this, it is sufficient to use an inclination adjusting mechanism composed of the support base 1013a and the actuator 1013b. As an observation method, coma aberration measurement using an interferometer or light collected on a disk surface using a microscope is used. A spot image or the like may be used. It is only necessary to aim for the minimum value of the coma aberration, and it is sufficient to minimize the side lobe component for the spot (step 116).
In general, in the optical recording medium 1008, the distance between the objective lens 1007 and the optical recording medium 1008 is not constant due to vibration from the outside or touching itself. However, in order to increase the storage density on the optical recording medium 1008, it is necessary to accurately focus the spot on the optical recording medium 1008. In the optical path of the reflected light from the optical recording medium 1008, there is provided a detection lens 1009 on which a convex lens surface that collects the reflected light to the light receiving element 1010 and a cylindrical lens surface that gives astigmatism to the reflected light are formed. Yes. When the position of the optical recording medium 1008 deviates from the position of the image of the semiconductor laser 1001 connected by the objective lens 1007, a deviation occurs between the position of the light receiving element 1010 and the reflected light condensing position, and the spot shape on the light receiving element 1010 changes. It changes because astigmatism is given by the cylindrical lens. A change in the spot shape on the light receiving element 1010 is detected by a known method, detected as a focus error signal, and the position of the objective lens 1007 is corrected based on the focus error signal. Thus, the optical recording medium 1008 is always controlled to be positioned at the position of the image of the semiconductor laser 1001 connected by the objective lens 1007. In order to perform the above operation, the light receiving element 1010 must be accurately positioned in a conjugate position with the semiconductor laser 1001, and an adjustment mechanism for correcting an influence due to an assembly error or the like is generally provided. It is. That is, in FIG. 26, the detection lens 1009 is held by the lens cell 1014, and the optical pickup device is assembled so that the light receiving element 1010 is in a conjugate position of the semiconductor laser 1001 by the movement of the lens cell 1014 in the optical axis direction. It is sometimes adjusted.

The light receiving element has a plurality of segments (not shown), and a predetermined light amount distribution needs to be incident on each segment, and the light receiving element holder can be moved in the plane perpendicular to the optical axis. It is installed in.
The detection lens 1009 and the light receiving element 1010 may be adjusted at the same time, and may be adjusted so that the signal becomes the best while detecting the reflected light from the optical recording medium 1008. For example, after roughly adjusting the lens cell 1014a and the light receiving element holder 1015a so that the signal light quantity becomes maximum, the focus signal amplitude and the track error signal amplitude become maximum and the offset becomes zero while actually applying the servo. Just drive into the position. In the best position, the cell 1014a and the holder 1015a are fixed to the housing 1030 by screws or adhesion (step 117).
The lens cell 1014a is a cylindrical lens holding member extending in the optical axis direction, and is held so that the outer periphery of the lens is inscribed in the cell, and is integrally formed as a single component. By inserting an eccentric pin, which is an assembling jig, into the hole 1014b and rotating it, the cell is moved relative to the housing 1030 in the optical axis direction. For the light receiving element holder 1015a, holes 1015b and 10c are provided on the holder 1015a, and a claw having a tip surface with a V-shaped tip section of the two rod-like members is inserted into the holes as the adjusting arm 1024a. The holder may be moved in the XY plane.
Japanese Patent No. 2616559 JP 2004-37865 A JP 2004-127469 A JP 2003-30858 A JP 2003-50303 A

However, the adjustment mechanism (cell or holder) in the conventional optical pickup apparatus not only causes an increase in the size of the optical pickup, but also requires a large adjustment jig for moving various parts finely and with high accuracy. Further, much labor and time are spent for adjustments such as having to reposition the pickup for each jig.
The present invention has been made in view of the above problems, and an object of the present invention is to provide an optical component, an optical pickup, and an adjustment method capable of suppressing the aberration of a spot condensed by an objective lens without a mechanical adjustment mechanism.

In order to solve this problem, the present invention provides a light source, a collimating lens that converts divergent light emitted from the light source into parallel light, and an objective lens that focuses a light beam on an optical recording medium. A light receiving element for detecting reflected light from the optical recording medium, wherein at least one of the collimating lens and the objective lens is one surface of a solid lens formed of resin or glass And a liquid lens in which a plurality of electrodes, an insulating layer, and an ultraviolet curable or thermosetting conductive liquid are sequentially laminated.
The collimating lens or objective lens mounted on the optical pickup of the present invention includes a solid lens formed of resin or glass, a plurality of electrodes, an insulating layer, an ultraviolet curable type or a thermosetting type conductive material on one surface of the solid lens. And a liquid lens in which droplets of a functional liquid are sequentially stacked.
According to a second aspect of the present invention, when the collimating lens is constituted by the liquid lens, the holder for fixing the light source and the collimating lens are adjusted by directly fixing the light source and the collimating lens to a housing of the optical pickup. The cell is unnecessary.
When the collimating lens is formed of a liquid lens, it is not necessary to adjust the position of the light source, and optical adjustment of the collimating lens can be electrically performed from the outside. Therefore, mechanically, the light source and the collimating lens can be directly fixed to the housing, and a holder and a cell are not required.
According to a third aspect of the present invention, a light source, a collimating lens for converting divergent light emitted from the light source into parallel light, an objective lens for condensing a light beam on the optical recording medium, and reflected light from the optical recording medium are detected. In the optical pickup comprising: a light receiving element that is disposed between the objective lens and the light receiving element; and a detection lens that collects reflected light from the optical recording medium toward the light receiving element. At least one of the objective lens and the detection lens has a plurality of electrodes, an insulating layer, and an ultraviolet curable or thermosetting conductive liquid laminated on one surface of a solid lens made of resin or glass. It is characterized by comprising a liquid lens.
At least one of the collimating lens, the objective lens, and the detection lens mounted on the optical pickup of the present invention includes a solid lens formed of resin or glass, a plurality of electrodes, an insulating layer, It is composed of a liquid lens in which droplets of an ultraviolet curable or thermosetting conductive liquid are sequentially stacked.

According to a fourth aspect of the present invention, when the detection lens is constituted by the liquid lens, a cell for adjusting the detection lens is not required by directly fixing the light source and the detection lens to a housing of the optical pickup. And
When the detection lens is formed of a liquid lens, it is not necessary to adjust the position of the light source, and optical adjustment of the detection lens can be electrically performed from the outside. Therefore, mechanically, the light source and the detection lens can be directly fixed to the housing, and the cell becomes unnecessary.
According to a fifth aspect of the present invention, the liquid lens is disposed so as not to be mixed with the conductive liquid and so that an insulating liquid having a different refractive index covers the conductive liquid.
The liquid lens may be configured such that an insulating liquid having a different refractive index covers the droplet without mixing with the droplet of the conductive liquid.
A sixth aspect of the present invention is the method of adjusting an optical pickup according to any one of the first to fifth aspects, wherein when the collimating lens is configured by the liquid lens, the adjustment of the collimating lens is performed by the conductive property. By selectively changing the voltage value between the liquid and each segment of the plurality of electrodes, the contact angle between the contact surfaces of the conductive liquid and the solid lens is changed, and the astigmatism amount of the incident beam of the objective lens And adjusting the tilt angle of the incident beam of the objective lens by changing the position in the plane perpendicular to the optical axis of the conductive liquid, and curing the conductive liquid by ultraviolet irradiation or heating. To do.
The collimating lens is composed of a solid lens and a liquid lens, and the liquid lens unit selectively changes the voltage value between the conductive liquid droplet and each segment of the plurality of electrodes, so that the conductive liquid droplet and the solid lens are changed. The amount of astigmatism of the objective lens incident beam was adjusted by changing the contact angle between the lens and the contact surface, and the tilt angle of the objective lens incident beam was adjusted by changing the position of the conductive liquid droplet in the optical axis vertical plane. In the state, the droplet is cured by ultraviolet irradiation or heating.

A seventh aspect of the present invention is the method of adjusting an optical pickup according to any one of the first to fifth aspects, wherein when the objective lens is constituted by the liquid lens, the tilt adjustment of the objective lens is performed by the conductive lens. The coma aberration of the spot image collected by the objective lens while changing the position in the optical axis vertical plane of the conductive liquid by selectively changing the voltage value between each segment of the conductive liquid and the plurality of electrodes The conductive liquid is cured by irradiating with ultraviolet rays or heating in a state where the amount is adjusted.
The objective lens is composed of a solid lens and a liquid lens, and the liquid lens unit selectively changes the voltage value between the conductive liquid droplet and each segment of the plurality of electrodes, thereby light of the conductive liquid droplet. While changing the position in the axis vertical plane, the droplet of the conductive liquid is cured by ultraviolet irradiation or heating in a state where the amount of coma of the spot image collected by the objective lens is adjusted.
An eighth aspect of the present invention is the method for adjusting an optical pickup according to any one of the first to fifth aspects, wherein when the detection lens is constituted by the liquid lens, the adjustment of the detection lens is performed by the conductive property. By selectively changing the voltage value between the liquid and each segment of the plurality of electrodes, the contact angle between the contact surfaces of the conductive liquid and the solid lens, and the position in the plane perpendicular to the optical axis of the conductive liquid are determined. While changing, the conductive liquid is cured by irradiating with ultraviolet rays or heating in a state in which the amplitude value of the track error signal or the focus error signal is adjusted to be substantially maximum.
The detection lens is composed of a solid lens and a liquid lens, and the liquid lens unit selectively changes the voltage value between the conductive liquid droplet and each segment of the plurality of electrodes, so that the conductive liquid droplet and the solid lens are changed. A state where the amplitude value of the track error signal or the focus error signal is adjusted to be substantially maximum while changing the contact angle between the contact surface with the lens and the position in the optical axis vertical plane of the droplet of the conductive liquid. The conductive liquid droplets are cured by ultraviolet irradiation or heating.
Claim 9 is an optical information processing apparatus for recording or reproducing information on an optical recording medium, and the optical information processing apparatus includes the optical pickup according to any one of claims 1 to 5. It is characterized by.
As an optical information processing apparatus for recording or reproducing information on an optical recording medium, the optical information processing apparatus includes the optical pickup according to any one of claims 1 to 5.

According to the first aspect of the present invention, the collimating lens or the objective lens mounted on the optical pickup includes a solid lens made of resin or glass, and a plurality of electrodes, an insulating layer, and an ultraviolet ray cured on one surface of the solid lens. Type or thermosetting type conductive liquid droplets are stacked in order, so as an optical pickup for recording or reproducing information on an optical recording medium, without a mechanical adjustment mechanism, Since the aberration of the spot condensed by the objective lens can be suppressed, the optical pickup can be reduced in size and thickness.
Further, in claim 2, since the collimating lens is composed of a liquid lens, it is not necessary to adjust the position of the light source, the optical adjustment of the collimating lens can be electrically performed from the outside, and the light source and the collimating lens are directly fixed to the housing. This eliminates the need for a holder or cell.
Further, in claim 3, the same effect as in claim 1 is obtained.
According to the fourth aspect of the present invention, since the detection lens is composed of a liquid lens, the detection lens can be optically adjusted externally, and mechanically the detection lens can be directly fixed to the housing. Is no longer necessary.
Further, in claim 5, since the liquid lens is arranged so as to cover the conductive liquid without mixing with the conductive liquid and with the refractive index different from that of the conductive liquid, It can seal and can guarantee stable operation.

According to the sixth aspect of the present invention, the astigmatism of the spot focused by the objective lens or the astigmatism of the beam before entering the objective lens can be suppressed without using a mechanical adjustment mechanism as an optical pickup assembly method. More specifically, a mechanical member for adjusting the position of a unit composed of a semiconductor laser, a collimating lens, or a unit composed of a semiconductor laser and a collimating lens becomes unnecessary. For this reason, the optical pickup can be reduced in size and thickness. Further, the assembly equipment for position adjustment of the unit composed of the semiconductor laser, the collimator lens, or the unit composed of the semiconductor laser and the collimator lens becomes unnecessary, and the assembly equipment can be reduced.
According to the seventh aspect of the present invention, as a method of assembling the optical pickup, the coma aberration of the spot condensed by the objective lens can be suppressed without using a mechanical adjustment mechanism. More specifically, a mechanical member for adjusting the tilt of the objective lens is not necessary. For this reason, the optical pickup can be reduced in size and thickness. In addition, the objective lens tilt adjustment assembly facility becomes unnecessary, and the assembly facility can be reduced.
According to the eighth aspect of the present invention, the spot on the light receiving element condensed by the detection lens can be optimized without using a mechanical adjustment mechanism as an assembly method of the optical pickup. More specifically, a mechanical member for adjusting the position of the detection lens becomes unnecessary. For this reason, the optical pickup can be reduced in size and thickness. Furthermore, the installation facility for adjusting the detection lens position is not necessary, and the assembly facility can be reduced.
According to the ninth aspect of the present invention, since an optical pickup having a small size is mounted, for example, it is difficult to mount the optical pickup in a half-height or notebook PC application.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. .
The basic idea of the present invention is to achieve the above object by realizing a lens in which a liquid lens and a solid lens utilizing electrocapillarity are bonded. Electrocapillary phenomenon refers to a phenomenon in which the contact angle of a droplet changes when a voltage is applied between the conductive liquid droplet and the electrode. The present invention uses this electrocapillary phenomenon to determine the focal length and lens position. Is applied on the basis of the principle configuration of a known technique (Patent Document 5: Japanese Patent Application Laid-Open No. 2003-50303) that makes it possible to move.
FIG. 1 is a diagram illustrating a liquid lens. The liquid lens consists of a droplet 8001 of a transparent liquid such as water having a diameter of a few microns to a few millimeters. The droplet 8001 is disposed on the transparent substrate 8002. The substrate is generally water repellent or has a water repellent coating. The liquid and the substrate are transparent to light having a wavelength in the use range, and the optical path is indicated by a reference light beam 8003. That is, the reference light beam 8003 that has passed through the liquid lens is collected from the contact surface between the droplet 8001 and the substrate 8002 to a focal point 8004 having a focal length f.
FIG. 2 is a diagram illustrating the angle between the insulating layer 8006 and the droplet 8005 and the electrocapillary phenomenon. The electrode 8007 is insulated from the droplet 8005 through the insulating layer 8006. The droplet 8005 may be a water droplet, for example. In the present invention, a material that can be cured by UV (ultraviolet light) or heat is used. What is necessary is just to select the conductive material used for adhesives, such as a well-known polyimide and azobenzene. When a voltage V is applied between the electrode 8007 and the droplet 8005, the contact area of the conductive droplet 8005 is expanded according to the electrocapillary phenomenon, and thus the droplet 8005 is deformed as shown by a broken line 8005a. When this technology is used, it is known that electric energy can be directly used to change the shape of the lens, so that the focus can be adjusted without mechanically moving the lens. In addition, Patent Document 5 describes that an electrode for moving a droplet in the plane perpendicular to the optical axis is arranged in addition to the electrode 8007. This part will be described in the embodiments of the present invention described below.

FIG. 3 is a cross-sectional view of a lens according to an embodiment of the present invention. A liquid lens 8011 and a solid lens 8012 are bonded together. The solid lens 8012 is made of glass or plastic. The liquid lens 8011 includes a droplet 8013 of a conductive liquid, which is a transparent liquid forming a lens shape, a substrate 8016, transparent electrodes 8015 and 8017 formed on both sides thereof, and an optical element on the droplet side of the transparent electrode 8015. A thin film insulating layer 8014 having transparency is formed. A water repellent coating (not shown) is provided between the insulating layer and the droplet 8013. The electrodes 8015 and 8017 are wired so that they can be connected to a control circuit (not shown).
FIG. 4 is a diagram for explaining a division pattern of transparent electrodes formed on both surfaces of the glass substrate 8016. The electrodes formed on both surfaces of the glass substrate 8016 are solid electrodes 8017 within the optical effective diameter, whereas 8015 is a pattern 8015a, 8015b, 8015c, 8015d obtained by dividing a circle into four as shown in FIG. It has become. As a method for applying the solid electrode 8017 (V0), any method may be used as long as it applies ground or an equal voltage. By controlling the input voltage to the electrodes 8015a, 8015b, 8015c, and 8015d, the droplet shape, specifically, the focal length and the position in the XY direction in the droplet optical axis vertical plane can be changed by the curvature radius control. In the lens of this embodiment, the liquid lens 8011 and the solid lens 8012 are made into one element, which can be used for changing the focal length of the entire lens, adjusting the tilt angle of the lens transmission beam, and correcting coma aberration.
FIG. 5 is a diagram for explaining a change in focal length, and FIG. 6 is a diagram showing a state seen from the upper surface of the electrode. When the electrodes 8015a, 8015b, 8015c, 8015d, and 8017 are equipotential, the droplet 8013 is at the substantially central position of the optical axis. This initial state is shown as state A (thick solid line) in FIG. On the other hand, when the electrodes 8015a, 8015b, 8015c, and 8015d are equipotential and the potential with respect to 8017 is shifted, the droplet 8013a spreads as in the state B (thick broken line), and the gap between the droplet and the insulating layer 8004 is increased. Is smaller. That is, the change of θ changes the radius of curvature of the liquid lens 8011 and changes the focal length of the liquid lens 8011. The change in the radius of curvature of the liquid lens 8011 also changes the transmission optical path to the solid lens 8012. As a result, the focal length of the entire lens changes.

FIG. 7 is a view for explaining the movement of the liquid lens portion in the optical axis vertical plane. FIG. 8 is a view showing a state viewed from the upper surface of the electrode. The electrodes 8015a, 8015b, 8015c, and FIG. 7 are diagrams for explaining that the position of the droplet 8013 can be changed in the XY direction by selectively controlling 8015d. When V4 is made larger than the others, it moves in the direction of a droplet 8013a as shown in FIG. The movement of the liquid lens in the X and Y directions causes a change in spherical shape deviated from the optical axis to the transmitted wavefront passing through the solid lens 8012. As a result, coma aberration changes occur as a whole lens. By utilizing this coma aberration change, coma aberration of the optical system can be corrected when the lens is mounted on an arbitrary optical system, in the present invention, an optical pickup.
In FIG. 4, the number of electrodes is four, but the number of electrodes, the electrode pattern, and the combination according to the desired lens drive may be determined. For example, if accuracy only in the radial direction is required, the electrode is divided into two in the X-axis direction. Only an electrode pattern may be used.
FIG. 9 is a diagram for explaining the movement of the liquid lens portion in the plane perpendicular to the optical axis. FIG. 10 is a view showing a state viewed from the upper surface of the electrode. As described above, the position of the droplet 8013 can be changed in the XY direction by selectively controlling the electrodes 8015a, 8015b, 8015c, and 8015d. Although FIGS. 7 and 8 describe the case where parallel light is incident on the lens, FIGS. 9 and 10 correspond to the case where the light emitted from the semiconductor laser is coupled by the lens, for example. That is, the movement of the liquid lens in the X and Y directions causes the optical axis to be shifted with respect to the solid lens 8012. As a result, the lens transmitted light beam is refracted. Using this relationship, the tilt angle of the light transmitted through the collimator lens can be adjusted.
3 to 10, the configuration of the liquid lens is not limited to one liquid. As shown in FIG. 11, the insulating liquid 8021 is disposed around the droplet 8013 which is a conductive liquid, and the holding member 8022 and the glass substrate. A configuration in which a unit constituted by 8023 is filled may be used. The insulating liquid 8021 and the conductive droplet 8013 are both transparent, and need only have values of almost the same density with different refractive indexes without being mixed with each other. Further, as shown in FIG. 12, the insulating liquid 8021 may be covered in a thin film around the droplet 8013 which is a conductive liquid.

FIG. 13 is a diagram showing the light condensing characteristics of a lens according to an embodiment of the present invention. The lens in FIG. 13 has a working wavelength: 410 nm and a focal length f: 1.218 mm.
FIG. 14 is a diagram showing numerical data of the lens of FIG. The symbols in FIG. 14 are as follows. “OBJ” means an object point (semiconductor laser as a light source), but the incident beam to the optical unit is “infinite system”, and “INFINITY (infinity)” with a radius of curvature: RDY and a thickness: THI is It means that the light source is at infinity. Unless otherwise specified, the unit of the quantity having the dimension of length is “mm”. “S1 (STO)” represents the entrance pupil plane, “S2” to “S3” represent the liquid lens 7001, “S4” to “S5” represent the solid lens 7002, “S2” represents the light source side surface of the optical unit, “ “S5” means the light collecting side. A thickness of 1 mm of “S2” means the droplet thickness of the liquid lens 7001. The thickness of “S3” of 0.1 mm represents the substrate thickness of the liquid lens. “S6” is a surface that matches the recording surface. “WL: Wavelength” represents a used wavelength (410 nm).
The aspherical shape of the fixed lens surface is: coordinate in the optical axis direction: X, coordinate in the optical axis orthogonal direction: Y, paraxial radius of curvature: R, conic constant: K, higher order coefficients: A, B, C, Using D, E, F,...
X = (Y ² / R) / [1+ (1− (1 + K) Y / R ² ) ^1/2 ] + AY ⁴ + BY ⁶ + CY ⁸ + DY ¹⁰ +... (1)
It is represented by
FIG. 15 shows a case where the focal length is specifically changed in such an optical unit. The abscissa indicates the radius of curvature of the liquid lens 7001 and the ordinate indicates the focal length. It can be seen that the focal length is reduced by the change in the radius of curvature.
On the other hand, FIG. 16 is an example of coma aberration change, where the horizontal axis indicates the X-direction position of the liquid lens 7001 and the vertical axis indicates the coma aberration. It can be seen that the coma increases due to the shift.
Further, FIG. 18 shows that the lens of FIG. 13 is focused, whereas the divergent beam from the light source is converted into parallel light. Here, FIG. 17 shows a change in the tilt angle of the transmitted beam when the position of the liquid lens 7001 in the X direction is changed. The above phenomenon is used for assembling parts of the optical pickup.

FIG. 19 is a configuration diagram of an optical pickup according to the first embodiment of the present invention. A difference from the conventional example of FIG. 26 is that the above-described lens composed of a solid lens and a liquid lens is used as the collimating lens 2002. This eliminates the need for the collimating lens cell and the semiconductor laser holder, and also eliminates the need for a jig device for adjusting the position of these. The size of the housing itself can be reduced by reducing the number of cells and holders. A broken line 200 in FIG. 19 indicates the housing size in FIG.
The optical components include a semiconductor laser 2001, a collimating lens 2002 that converts the radiation emitted from the semiconductor laser 2001 into a parallel light beam, a triangular beam shaping prism 2003, a polarizing beam splitter 2004, 1 / A four-wavelength plate 2005, a deflection mirror 2006, an objective lens 2007, an optical recording medium 2008, a detection lens 2009, and a light receiving element 2010 are configured.
The emitted light of the semiconductor laser 2001 is converted into a parallel light beam by the collimator lens 2002 and then enters the beam shaping prism. In general, since the emitted light of a semiconductor laser has a horizontal radiation angle narrower than a vertical radiation angle, a cross section perpendicular to the optical axis of parallel light is elliptical. Therefore, by expanding the horizontal beam of parallel light by the shaping prism 2003 having a triangular prism shape, a cross section perpendicular to the optical axis of the elliptical parallel light approaches a circle. Then, the light passes through the polarizing beam splitter 2004, passes through the quarter-wave plate 2005, becomes circularly polarized light, is deflected by 90 ° in the optical path to the deflecting mirror 2006, enters the objective lens 2007, and is collected as a minute spot on the optical recording medium 2008. Be lit. Information is reproduced, recorded or erased by this spot. The light reflected from the optical recording medium 2008 becomes circularly polarized light in the opposite direction to the outward path, and again becomes substantially parallel light, passes through the wave plate 2005, becomes linearly polarized light orthogonal to the forward path, and is reflected by the polarization beam splitter 2004. The light is converged by the detection lens 2009 and reaches the light receiving element 2010 having a plurality of light receiving segments. An information signal and a servo signal are detected from the light receiving element 2010.

Now, components mounted on such an optical pickup are required to be assembled with high accuracy in order to reproduce or write information from an optical recording medium. Hereinafter, the assembly procedure will be described with reference to the flowcharts of FIGS. 19 and 20.
First, the beam shaping prism 2003, the polarizing beam splitter 2004, the quarter wavelength plate 2005, the deflection mirror 2006, the semiconductor laser 2001, and the collimator lens 2002 are bonded and fixed to the housing 2030 (step 201). These are provided with positioning references on the housing 2030, and are bonded and fixed in accordance with these references.
Next, the light receiving element 2010 is bonded and fixed to the light receiving element holder 2015a (step 202), and the detection lens 2009 is bonded and fixed to the lens cell 2014a (step 204). Then, the holder 2015a and the cell 2014a are temporarily fixed to the housing 2030 (steps 203 and 205). The holder 2015a is bonded to the light receiving element 2010 in a plane perpendicular to the optical axis, and a plate-like member has a window, and is fixed in a state where the light receiving element is inserted therein. Further, the holder is provided with holes 2015b and c, which are used to move the holder relative to the housing 2030 in the plane perpendicular to the optical axis by inserting the tip of the assembly jig into the hole. .
The lens cell 2014a is a cylindrical lens holding member extending in the optical axis direction, is held so that the outer periphery of the lens is inscribed in the cell, and is integrally formed as a single component. The cell is further provided with a hole 2014b which is used to move the cell relative to the housing 2030 in the direction of the optical axis by inserting the tip of an assembling jig, for example, an eccentric pin. To do.

Further, according to FIG. 28, the position of the light emitting point 26 of the laser chip 2 has a variation up to about 80 μm with respect to the center line 35 of the base 3. In addition, it is generally known from FIG. 29 that coma and astigmatism increase as the image height increases. It is known that when there is coma or astigmatism, a spot image condensed on the optical recording medium is deteriorated. Therefore, in the present embodiment, since a combination of a solid lens and a liquid lens is used as the lens 2002, the displacement of the liquid lens in the optical axis vertical plane (XY) is given as a relative state between the solid lens and the liquid lens. Thus, the direction of the beam after transmission is controlled. For example, when the lower surface of the housing in FIG. 19 is used as the reference surface of the pickup, the rising light is adjusted to be substantially perpendicular to the reference surface (step 206). Specifically, an installation surface of a jig (not shown) for installing the housing 2030 is observed with an autoremeter (not shown) or the like, and then the housing 2030 is installed, the semiconductor laser is turned on, and the deflection mirror is used. It is possible to ensure vertical rising light by making it coincide with the installation surface while observing the rising light with auto collimator.
Subsequently, adjustment is performed to cause the semiconductor laser 2001 to emit light and to remove astigmatism of the laser light that has passed through the collimator lens 2002. In general, the emitted light of a semiconductor laser has an astigmatic difference that the light emitting point position is shifted between the horizontal direction and the vertical direction. The light emitting point position in the vertical direction is almost at the laser emitting end face, but the light emitting point position in the horizontal direction is often moved inward from the emitting end face in units of several μm to several tens of μm. For this reason, when the emitted light is collected, astigmatism occurs also at the condensing point, and it becomes difficult to form a minute spot. On the other hand, the beam shaping prism 2003 causes astigmatism in transmitted light when incident light deviates from parallel light and becomes convergent light or divergent light. For this reason, the optical pickup configured as shown in FIG. 19 shifts the incident light to the shaping prism from the parallel light by changing the interval between the collimating lens 2002 and the semiconductor laser 2001, and cancels the astigmatism of the objective lens incident beam. Although correction is performed, in this embodiment, a combination of a solid lens and a liquid lens is used as the lens 2002. Therefore, the parallel distance of the transmitted beam is changed by changing the focal length of the liquid lens instead of the lens interval. You can control the degree.
Specifically, it is only necessary to use an autocollimator (not shown) used for the laser emission light adjustment described above so that the parallel light is obtained while observing the rising light from the deflection mirror. Alternatively, a wavefront aberration measurement interferometer or the like may be disposed instead of the autocollimator so as to minimize astigmatism.

As described above, the liquid lens is cured at the liquid lens best position (XY) and the focal length obtained by adjusting the tilt angle of the beam before entering the objective lens and adjusting the astigmatism (collimating lens adjustment). . If a resin that cures by UV (ultraviolet) irradiation is used as the liquid lens, the liquid lens unit is irradiated from the outside by a UV exposure machine, and if a thermosetting resin is used, the liquid lens unit is heated by a heater or the like. That's fine.
In the conventional example of FIG. 26, it is necessary to move the two components of the semiconductor laser and the collimating lens. In this embodiment, however, only the liquid lens part of the collimating lens needs to be adjusted. In addition, since the electrical adjustment is performed, the optical pickup can be reduced in size and jigs can be eliminated.
Next, the objective lens 2007 is bonded and fixed at a position where an opening for passing the optical path of the actuator is formed (step 207). And what was temporarily assembled with 2013a which is a support base of an actuator is temporarily installed on a housing (process 208,209).
12, the laser chip 2 of the semiconductor laser 1 is mounted on the base 3 and sealed with a cap 4 with a window glass. The emission direction (intensity distribution center) 6 of the laser light 5 emitted from the laser chip 2 has a variation of about 3 ° with respect to the perpendicular of the base 3. As a result, the light quantity of the semiconductor laser is shifted from the optical axis. In FIG. 19, if the emission direction (intensity distribution center) of the semiconductor laser 2001 is shifted with respect to the common optical axis of the objective lens 2007 and the collimator lens 2006, the intensity distribution of the laser light reaching the light receiving element 2010 is shifted. In addition, problems such as occurrence of an offset in the output signal, particularly a track shift signal and a focus shift signal that use a change in light intensity distribution in the light receiving element 2010 are likely to occur. For this reason, it is desired to adjust the emission direction (intensity distribution center) to coincide with the optical axis of the objective lens.
Specifically, after the objective lens support base 2013a is temporarily installed on the housing, the objective lens is moved relative to the housing 2030 in the plane perpendicular to the optical axis while holding the support base 2013a with an arm (not shown) or the like. What is necessary is just to search for the position where the light quantity distribution of the transmitted light is maximized or the position where the balance of the light quantity distribution is equal. At that position, the support base 2013a may be bonded to the housing (step 210).

The structure of the actuator will be described with reference to FIG. A hole 55 is provided in the actuator 2013b. The hole portions 55 are provided for inserting angle adjusting screws 11 described later. The positions of the hole portions 55 are, for example, the positions of the hole portions 55 at the center point of the opening portion 27 of the actuator 2013b. It is made to be the vertex of an equilateral triangle in the center. The spherical washer 6 is attached to the actuator 2013b as described later. In the optical pickup, the hole 55 is provided as described above, so that the actuator 2013b and the support base 2013a are fixed by the angle adjusting screw 11 at three points.
The spherical washer 6 is a ring-shaped metal having an opening 28 having a diameter equivalent to that of the opening 26 of the bobbin 23 at the center, and has an attachment reference surface 49 that is a part of a spherical surface. The spherical washer 6 is positioned and fixed so that the center of the opening 28 coincides with the center of the opening 26 of the actuator 2013b. This fixing is, for example, by adhesion.
Next, the support base 2013 a has an opening 29, a mounting reference surface 48, and a screw hole 56. The opening 29 has a diameter equivalent to that of the laser beam incident from below vertically. The mounting reference surface 48 is formed by a concave portion having the same spherical surface as the mounting reference surface 49 of the spherical washer 6, and the mounting reference surface 49 of the spherical washer 6 that is convex by this and the mounting reference surface 48 that is concave are formed. To be matched. The screw hole 56 is provided for screwing the angle adjusting screw 11, and the actuator 2013 b is attached to the support base 2013 a and the mounting reference surface 49 of the spherical washer 6 and the support base as described above. When arranged in contact with the attachment reference surface 48 of 2013a, the position corresponds to the hole 55 described above.
The actuator 2013b and the support base 2013a configured as described above are attached by the angle adjusting screw 11 as shown in FIG. As shown in the drawing, after the angle adjusting screw 11 is inserted into the hole 55 of the actuator 2013b, the angle adjusting screw 11 is screwed into the screw hole 56 of the support base 2013a in a state where the spring 70 is inserted on the lower surface side of the actuator 2013b.

As described above, by changing the tightening degree of each of the three angle adjusting screws 11, the mounting reference surface 49 of the spherical washer 6 is supported within the spherical surface centered on the principal point of the objective lens 2007, for example. It slides on the mounting reference surface 48 of the base 2013a, and the inclination angle of the actuator 2013b with respect to the support base 2013a can be adjusted. The position where the angle adjusting screw is screwed is the position of the hole 55 of the actuator 2013b described above, that is, the apex of an equilateral triangle centering on the center point of the openings 26 and 29. By adjusting the screws, the inclination angle between the actuator 2013b and the support base 2013a can be freely adjusted in any direction. And the inclination of the actuator 2013b and the support base 2013a can be adjusted by adjusting the angle adjusting screw 11 in this way.
Further, it is known that the objective lens 2007 itself has an aberration. Among them, the coma aberration component can be canceled by tilting the objective lens with respect to the incident optical axis. For this, an inclination adjusting mechanism composed of the support base 2013a and the actuator 2013b may be used. As an observation method, coma aberration, a spot image condensed on the disk surface, or the like may be used. . For coma, the minimum value may be aimed at, and for the spot, the sidelobe component should be minimized (step 211).
Note that in step 211, not only the objective lens but also coma aberration that the incident beam already has can be corrected. For example, the coma remaining in the transmitted beam in step 206 can also be reduced here.

  In general, the distance between the objective lens 2007 and the optical recording medium 2008 is not constant due to external vibration or surface contact with the optical recording medium 2008. However, in order to increase the storage density on the optical recording medium 2008, it is necessary to accurately focus the spot on the optical recording medium 2008. In the optical path of the reflected light from the optical recording medium 2008, there is provided a detection lens 2009 on which a convex lens surface that collects the reflected light to the light receiving element 2010 and a cylindrical lens surface that gives astigmatism to the reflected light are formed. Yes. When the position of the optical recording medium 2008 is deviated from the position of the image of the semiconductor laser 2001 connected by the objective lens 2007, the position of the light receiving element 2010 and the position where the reflected light is condensed are displaced, and the spot shape on the light receiving element 2010 is changed. It changes because astigmatism is given by the cylindrical lens. A change in the spot shape on the light receiving element 2010 is detected by a known method, detected as a focus error signal, and the position of the objective lens 2007 is corrected based on the focus error signal. Thus, the optical recording medium 2008 is always controlled to be positioned at the position of the image of the semiconductor laser 2001 connected by the objective lens 2007. In order to perform the above operation, the light receiving element 2010 must be accurately positioned in a conjugate position with the semiconductor laser 2001, and an adjustment mechanism for correcting the influence due to an assembly error or the like is generally provided. It is. That is, in FIG. 19, the detection lens 2009 is held by the lens cell 2014, and the optical pickup device is assembled so that the light receiving element 2010 is conjugated to the semiconductor laser 2001 by the movement of the lens cell 2014 in the optical axis direction. It is sometimes adjusted.

The light receiving element has a plurality of segments (not shown), and a predetermined light amount distribution needs to be incident on each segment, and the light receiving element holder can be moved in the plane perpendicular to the optical axis. It is installed in.
The detection lens 2009 and the light receiving element 2010 may be adjusted at the same time, and may be adjusted so that the signal becomes the best while detecting the reflected light from the optical recording medium 2008. For example, after roughly adjusting the lens cell 2014a and the light receiving element holder 2015a so that the signal light quantity becomes maximum, the focus signal amplitude and the track error signal amplitude become maximum and the offset becomes zero while actually applying the servo. Just drive into the position. In the best position, the cell 2014a and the holder 2015a are fixed to the housing 2030 by screws or adhesion (step 212).
The lens cell 2014a is a cylindrical lens holding member extending in the optical axis direction. The lens cell 2014a is held so that the outer periphery of the lens is inscribed in the cell, and is integrally formed as a single component. By inserting an eccentric pin as an assembly jig into the hole 2014b and rotating it, the cell is moved relative to the housing 2030 in the optical axis direction. As for the light receiving element holder 2015a, holes 2015b and c are provided on the holder 2015a, and a claw having a tip surface having a V-shaped tip section of the two rod-like members is inserted into the holes as the adjusting arm 2024a. The holder may be moved in the XY plane.

FIG. 21 is a configuration diagram of an optical pickup according to the second embodiment of the present invention. In contrast to the first embodiment of FIG. 19, a lens in which a solid lens and a liquid lens are combined is used as the objective lens in addition to the collimating lens. Thereby, the two parts formed from the support base and the lens holding part shown in the conventional example of FIG. 26 and the first embodiment of FIG. 19 can be made into one part, and the thickness of the pickup can be reduced. It becomes possible. Further, in the conventional example of FIG. 26 and the actuator configuration of the first embodiment of FIG. 19, a jig for adjusting screw tightening at three points is necessary for adjusting the lens tilt. Can do. Further, in the conventional example of FIG. 26 and the first embodiment of FIG. 19, a sufficient space on the housing is required for inserting the jig, but this can also be eliminated, and the pickup can be downsized. . 21 indicates the housing size of FIG.
As optical components, there are a semiconductor laser 3001, a collimating lens 3002 for converting radiated light emitted from the semiconductor laser 3001 into a parallel light beam, a triangular beam shaping prism 3003, a polarizing beam splitter 3004, and a quarter. It comprises a wave plate 3005, a deflection mirror 3006, an objective lens 3007, an optical recording medium 3008, a detection lens 3009, and a light receiving element 3010.
The emitted light of the semiconductor laser 3001 is converted into a parallel light beam by the collimator lens 3002, and then enters the beam shaping prism. In general, since the emitted light of a semiconductor laser has a horizontal radiation angle narrower than a vertical radiation angle, a cross section perpendicular to the optical axis of parallel light is elliptical. Therefore, by expanding the horizontal beam of parallel light by the shaping prism 3003 having a triangular prism shape, a cross section perpendicular to the optical axis of the elliptical parallel light approaches a circle. Then, the light passes through the polarizing beam splitter 3004, passes through the quarter-wave plate 3005, becomes circularly polarized light, is deflected by 90 ° to the deflecting mirror 3006, enters the objective lens 3007, and is collected as a minute spot on the optical recording medium 3008. Lighted. Information is reproduced, recorded or erased by this spot. The light reflected from the optical recording medium 3008 becomes circularly polarized light in the opposite direction to the outward path, and again becomes substantially parallel light, passes through the wave plate 3005, becomes linearly polarized light orthogonal to the forward path, and is reflected by the polarizing beam splitter 3004. The light is converged by the detection lens 3009 and reaches the light receiving element 3010 having a plurality of light receiving segments. An information signal and a servo signal are detected from the light receiving element 3010.

Now, components mounted on such an optical pickup are required to be assembled with high accuracy in order to reproduce or write information from an optical recording medium. Hereinafter, the assembly procedure will be described with reference to the flowcharts of FIGS. 21 and 22.
The beam shaping prism 3003, the polarization beam splitter 3004, the quarter wavelength plate 3005, the deflection mirror 3006, the semiconductor laser 3001, and the collimator lens 3002 are bonded and fixed to the housing 3030 (step 301). These are provided with positioning references on the housing 3030, and are fixedly bonded in accordance with these references.
Next, the light receiving element 3010 is bonded and fixed to the light receiving element holder 3015a (step 302), and the detection lens 3009 is bonded and fixed to the lens cell 3014a (step 304). Then, the holder 3015a and the cell 3014a are temporarily fixed to the housing 3030 (steps 303 and 305).
The holder 3015a is bonded to the light receiving element 3010 in the plane perpendicular to the optical axis, and has a window in a plate-like member, and is fixed with the light receiving element inserted therein. Further, the holder is provided with holes 3015b and c, which are used to move the holder relative to the housing 3030 in the plane perpendicular to the optical axis by inserting the tip of the assembly jig into the hole. .
The lens cell 3014a is a cylindrical lens holding member extending in the optical axis direction, and is held so that the outer periphery of the lens is inscribed in the cell, and is integrally formed as a single component. The cell is further provided with a hole 3014b, which is used to move the cell relative to the housing 3030 in the direction of the optical axis by inserting an assembly jig, for example, the tip of an eccentric pin into the hole. To do.

Further, according to FIG. 28, the position of the light emitting point 26 of the laser chip 2 has a variation up to about 80 μm with respect to the center line 35 of the base 3. In addition, it is generally known from FIG. 29 that coma and astigmatism increase as the image height increases. It is known that when there is coma or astigmatism, a spot image condensed on the optical recording medium is deteriorated. Therefore, in this embodiment, a combination of a solid lens and a liquid lens is used as the lens 3002. Therefore, the displacement in the optical axis vertical plane (XY) of the liquid lens is given as a relative state between the solid lens and the liquid lens. Thus, the direction of the beam after transmission is controlled. For example, when the lower surface of the housing in FIG. 21 is used as the reference surface of the pickup, the rising light is adjusted to be substantially perpendicular to the reference surface (step 306).
Specifically, an installation surface of a jig (not shown) for installing the housing 3030 is observed with an autoremeter (not shown) or the like, and then the housing 3030 is installed, the semiconductor laser is turned on, and the deflection mirror is used. It is possible to ensure vertical rising light by making it coincide with the installation surface while observing the rising light with auto collimation.
Subsequently, adjustment is performed to cause the semiconductor laser 3001 to emit light and to remove astigmatism of the laser light that has passed through the collimator lens 3002. In general, the emitted light of a semiconductor laser has an astigmatic difference that the light emitting point position is shifted between the horizontal direction and the vertical direction. The light emitting point position in the vertical direction is almost at the laser emitting end face, but the light emitting point position in the horizontal direction is often moved inward from the emitting end face in units of several μm to several tens of μm. For this reason, when the emitted light is collected, astigmatism occurs also at the condensing point, and it becomes difficult to form a minute spot. On the other hand, the beam shaping prism 3003 causes astigmatism in transmitted light when incident light deviates from parallel light and becomes convergent light or divergent light. For this reason, in the optical pickup configured as shown in FIG. 21, the incident light to the shaping prism is shifted from the parallel light by changing the distance between the collimating lens 3002 and the semiconductor laser 3001, thereby canceling the astigmatism of the objective lens incident beam. Although correction is performed, in this embodiment, since a combination of a solid lens and a liquid lens is used as the lens 3002, the parallel of the transmitted beam is changed by changing the focal length of the liquid lens instead of the lens interval. You can control the degree.
Specifically, it is only necessary to use an autocollimator (not shown) used for the laser emission light adjustment described above so that the parallel light is obtained while observing the rising light from the deflection mirror. Alternatively, a wavefront aberration measurement interferometer or the like may be disposed instead of the autocollimator so as to minimize astigmatism.

As described above, the liquid lens is cured at the liquid lens best position (XY) and the focal length obtained by adjusting the tilt angle of the beam before entering the objective lens and adjusting the astigmatism (collimating lens adjustment). . If a resin that cures by UV (ultraviolet) irradiation is used as the liquid lens, the liquid lens unit is irradiated from the outside by a UV exposure machine, and if a thermosetting resin is used, the liquid lens unit is heated by a heater or the like. That's fine.
In the conventional example of FIG. 26, it is necessary to move the two components of the semiconductor laser and the collimating lens. However, in this embodiment, only the liquid lens portion of the collimating lens needs to be adjusted, and the displacement method is also a mechanical method. In addition, since the electrical adjustment is performed, it is possible to reduce the size of the optical pickup and eliminate the need for a jig.
Next, the objective lens 3007 is adhered and fixed at a position where an opening for passing the optical path of the actuator is formed (step 307), and temporarily installed on the housing (step 308).
Referring to FIG. 28, the laser chip 2 of the semiconductor laser 1 is mounted on a base 3 and sealed with a cap 4 with a window glass. The emission direction (intensity distribution center) 6 of the laser light 5 emitted from the laser chip 2 has a variation of about 3 ° with respect to the perpendicular of the base 3. As a result, the light quantity of the semiconductor laser is shifted from the optical axis. In FIG. 21, if the emission direction (intensity distribution center) of the semiconductor laser 3001 is deviated from the common optical axis of the objective lens 3007 and the collimating lens 3006, the intensity distribution of the laser light reaching the light receiving element 3010 is deviated. In addition, problems such as occurrence of an offset in an output signal, particularly a track shift signal and a focus shift signal using the light intensity distribution change in the light receiving element 3010 are likely to occur. For this reason, it is desired to adjust the emission direction (intensity distribution center) to coincide with the optical axis of the objective lens.
Specifically, after the objective lens actuator 3013b is temporarily installed on the housing, it is moved relative to the housing 3030 in the plane perpendicular to the optical axis while holding 3013b with an arm (not shown), and the light amount distribution of the objective lens transmitted light. What is necessary is just to search for a position where the maximum value is obtained, or a position where the balance of the light quantity distribution is uniform. At that position, the actuator 3013b may be bonded to the housing (step 309).

Further, it is known that the objective lens 3007 itself has an aberration. As the coma aberration correcting method, in the first embodiment of FIG. 19, the objective lens is canceled by tilting with respect to the incident optical axis. As a result, an actuator structure as shown in FIG. 30 was required. However, in this embodiment, since a combination of a solid lens and a liquid lens is used as the lens 3007, an optical axis vertical position (XY) displacement of the liquid lens is given as a relative state between the solid lens and the liquid lens. As a result, frame adjustment of the focused spot is performed. As an observation method, coma aberration, a spot image condensed on the disk surface, or the like may be used. For coma, the minimum value may be aimed at, and for the spot, the sidelobe component should be minimized (step 310).
In step 310, not only the objective lens but also the coma aberration that the incident beam already has can be corrected. For example, coma remaining in the transmitted beam in step 306 can also be reduced here.
The liquid lens is cured at the above-described liquid lens best position (XY). If a resin that cures by UV (ultraviolet) irradiation is used as the liquid lens, the liquid lens unit is irradiated from the outside by a UV exposure machine, and if a thermosetting resin is used, the liquid lens unit is heated by a heater or the like. That's fine.

In general, in the optical recording medium 3008, the distance between the objective lens 3007 and the optical recording medium 3008 is not constant due to vibration from the outside or touching itself. However, in order to increase the storage density on the optical recording medium 3008, it is necessary to accurately focus the spot on the optical recording medium 3008. In the optical path of the reflected light from the optical recording medium 3008, there is provided a detection lens 3009 on which a convex lens surface that collects the reflected light to the light receiving element 3010 and a cylindrical lens surface that gives astigmatism to the reflected light are formed. Yes. When the position of the optical recording medium 3008 deviates from the position of the image of the semiconductor laser 3001 connected by the objective lens 3007, a deviation occurs between the position of the light receiving element 3010 and the reflected light condensing position, and the spot shape on the light receiving element 3010 is changed. It changes because astigmatism is given by the cylindrical lens. A change in the spot shape on the light receiving element 3010 is detected by a known method, detected as a focus error signal, and the position of the objective lens 3007 is corrected based on the focus error signal. Thus, the optical recording medium 3008 is always controlled to be positioned at the position of the image of the semiconductor laser 3001 connected by the objective lens 3007. In order to perform the above operation, the light receiving element 3010 must be accurately positioned in a conjugate position with the semiconductor laser 3001, and an adjustment mechanism for correcting the influence of an assembly error or the like is generally provided. It is. That is, in FIG. 21, the detection lens 3009 is held by the lens cell 3014, and the optical pickup device is assembled so that the light receiving element 3010 is positioned at a conjugate position of the semiconductor laser 3001 by the movement of the lens cell 3014 in the optical axis direction. It is sometimes adjusted.
The light receiving element has a plurality of segments (not shown), and a predetermined light amount distribution needs to be incident on each segment, and the light receiving element holder can be moved in the plane perpendicular to the optical axis. It is installed in.
The detection lens 3009 and the light receiving element 3010 may be adjusted at the same time, and may be adjusted so that the signal becomes the best while detecting the reflected light from the optical recording medium 3008. For example, after roughly adjusting the lens cell 3014a and the light receiving element holder 3015a so that the signal light amount becomes maximum, the focus signal amplitude and the track error signal amplitude become maximum and the offset becomes zero while actually applying the servo. Just drive into the position. At the best position, the cell 3014a and the holder 3015a are fixed to the housing 3030 by screws or adhesion (step 311).
The lens cell 3014a is a cylindrical lens holding member extending in the optical axis direction, and is held so that the outer periphery of the lens is inscribed in the cell, and is integrally formed as a single component. The eccentric pin, which is an assembly jig, is inserted into the hole 3014b and rotated to move the cell relative to the housing 3030 in the optical axis direction. For the light receiving element holder 3015a, holes 3015b and 30c are provided on the holder 3015a, and a claw having a tip surface with a V-shaped tip section of the two rod-like members is inserted into the holes as the adjustment arm 3024a. The holder may be moved in the XY plane.

FIG. 23 is an optical pickup configuration diagram according to the third embodiment of the present invention. In contrast to the first and second embodiments shown in FIGS. 19 and 21, in addition to the collimating lens and the objective lens, the detection lens uses a combination of a solid lens and a liquid lens. This eliminates the need for the detection lens cell and the light receiving element holder as compared with the conventional example of FIG. 26 and the first and second embodiments of FIGS. No equipment was needed. The size of the housing itself can be reduced by reducing the number of cells and holders. The broken line in FIG. 23 indicates the housing size in FIG.
As optical components, there are a semiconductor laser 4001, a collimating lens 4002 for converting radiated light emitted from the semiconductor laser 4001 into a parallel light beam, a triangular beam shaping prism 4003, a polarizing beam splitter 4004, and a quarter. It comprises a wave plate 4005, a deflection mirror 4006, an objective lens 4007, an optical recording medium 4008, a detection lens 4009, and a light receiving element 4010. A difference from the conventional example of FIG. 26 and the first and second embodiments of FIGS. 19 and 21 is that a combination of a liquid lens and a solid lens is used as a detection lens.
The emitted light of the semiconductor laser 4001 is converted into a parallel light beam by the collimator lens 4002 and then enters the beam shaping prism. In general, since the emitted light of a semiconductor laser has a horizontal radiation angle narrower than a vertical radiation angle, a cross section perpendicular to the optical axis of parallel light is elliptical. Therefore, by expanding the horizontal beam of parallel light by the shaping prism 4003 having a triangular prism shape, a cross section perpendicular to the optical axis of the elliptical parallel light approaches a circle. Then, the light passes through the polarizing beam splitter 4004, passes through the quarter-wave plate 4005, becomes circularly polarized light, is deflected by 90 ° to the deflecting mirror 4006, enters the objective lens 4007, and is collected as a minute spot on the optical recording medium 4008. Be lit. Information is reproduced, recorded or erased by this spot. The light reflected from the optical recording medium 4008 becomes circularly polarized light in the opposite direction to the outward path, becomes again substantially parallel light, passes through the wave plate 4005, becomes linearly polarized light orthogonal to the forward path, and is reflected by the polarizing beam splitter 4004. The light is converged by the detection lens 4009 and reaches a light receiving element 4010 having a plurality of light receiving segments. An information signal and a servo signal are detected from the light receiving element 4010.

Now, components mounted on such an optical pickup are required to be assembled with high accuracy in order to reproduce or write information from an optical recording medium. Hereinafter, the assembly procedure will be described with reference to the flowcharts of FIGS.
First, the beam shaping prism 4003, the polarizing beam splitter 4004, the quarter wavelength plate 4005, the deflection mirror 4006, the semiconductor laser 4001, the collimator lens 4002, the light receiving element 4010, and the detection lens 4009 are bonded and fixed to the housing 4030 (step 401). These are provided with positioning references in the housing 4030, and are bonded and fixed in accordance with these references.
Further, according to FIG. 28, the position of the light emitting point 26 of the laser chip 2 has a variation up to about 80 μm with respect to the center line 35 of the base 3. In addition, it is generally known from FIG. 29 that coma and astigmatism increase as the image height increases. It is known that when there is coma or astigmatism, a spot image condensed on the optical recording medium is deteriorated. Therefore, in the present embodiment, since the lens 4002 is a combination of a solid lens and a liquid lens, a displacement in the optical axis vertical plane (XY) of the liquid lens is given as a relative state between the solid lens and the liquid lens. Thus, the direction of the beam after transmission is controlled. For example, when the lower surface of the housing in FIG. 23 is used as the reference surface of the pickup, the rising light is adjusted to be substantially perpendicular to the reference surface (step 402).
Specifically, an installation surface of a jig (not shown) for installing the housing 4030 is observed with an auto-remeter (not shown) or the like, and then the housing 4030 is installed, the semiconductor laser is turned on, and the deflection mirror is used. It is possible to ensure vertical rising light by making it coincide with the installation surface while observing the rising light with auto collimator.

Subsequently, adjustment is performed to cause the semiconductor laser 4001 to emit light and to remove astigmatism of the laser light that has passed through the collimator lens 4002. In general, the emitted light of a semiconductor laser has an astigmatic difference that the light emitting point position is shifted between the horizontal direction and the vertical direction. The light emitting point position in the vertical direction is almost at the laser emitting end face, but the light emitting point position in the horizontal direction is often moved inward from the emitting end face in units of several μm to several tens of μm. For this reason, when the emitted light is collected, astigmatism occurs also at the condensing point, and it becomes difficult to form a minute spot. On the other hand, the beam shaping prism 4003 causes astigmatism in transmitted light when incident light deviates from parallel light and becomes convergent light or divergent light. Therefore, in the optical pickup configured as shown in FIG. 23, the interval between the collimating lens 4002 and the semiconductor laser 4001 is changed to shift the incident light to the shaping prism from the parallel light, thereby canceling the astigmatism of the objective lens incident beam. Although correction is performed, in this embodiment, a combination of a solid lens and a liquid lens is used as the lens 4002. Therefore, the parallel distance of the transmitted beam is changed by changing the focal length of the liquid lens instead of the lens interval. You can control the degree.
Specifically, it is only necessary to use an autocollimator (not shown) used for the laser emission light adjustment described above so that the parallel light is obtained while observing the rising light from the deflection mirror. Alternatively, a wavefront aberration measurement interferometer or the like may be disposed instead of the autocollimator so as to minimize astigmatism.
As described above, the liquid lens is cured at the liquid lens best position (XY) and the focal length obtained by adjusting the tilt angle of the beam before entering the objective lens and adjusting the astigmatism (collimating lens adjustment). . If a resin that cures by UV (ultraviolet) irradiation is used as the liquid lens, the liquid lens unit is irradiated from the outside by a UV exposure machine, and if a thermosetting resin is used, the liquid lens unit is heated by a heater or the like. That's fine.
In the conventional example of FIG. 26, it is necessary to move the two components of the semiconductor laser and the collimating lens. In this embodiment, however, only the liquid lens part of the collimating lens needs to be adjusted. In addition, since the electrical adjustment is performed, the optical pickup can be reduced in size and jigs can be eliminated.

Next, the objective lens 4007 is adhered and fixed at a position where an opening for passing the optical path of the actuator is formed (step 403), and temporarily installed on the housing (step 405).
28, the laser chip 2 of the semiconductor laser 1 is mounted on the base 3 and sealed with a cap 4 with a window glass. The emission direction (intensity distribution center) 6 of the laser light 5 emitted from the laser chip 2 has a variation of about 3 ° with respect to the perpendicular of the base 3. As a result, the light quantity of the semiconductor laser is shifted from the optical axis. In FIG. 23, if the emission direction (intensity distribution center) of the semiconductor laser 4001 is deviated from the common optical axis of the objective lens 4007 and the collimating lens 4006, the intensity distribution of the laser light reaching the light receiving element 4010 is deviated. In addition, problems such as occurrence of an offset in an output signal, in particular, a track shift signal or a focus shift signal using a light intensity distribution change in the light receiving element 4010 are likely to occur. For this reason, it is desired to adjust the emission direction (intensity distribution center) to coincide with the optical axis of the objective lens.
Specifically, after the objective lens actuator 4013b is temporarily installed on the housing, it is moved relative to the housing 4030 in the optical axis vertical plane while holding the arm 4013b by an arm (not shown), and the light quantity distribution of the objective lens transmitted light. What is necessary is just to search for the position where the maximum is or the position where the balance of the light quantity distribution is equal. At that position, the actuator 4013b may be bonded to the housing (step 405).

Further, it is known that the objective lens 4007 itself has an aberration. As the coma aberration correcting method, in the first embodiment of FIG. 19, the objective lens is canceled by tilting with respect to the incident optical axis. As a result, an actuator structure as shown in FIG. 30 was required. However, in this embodiment, since the lens 4007 is a combination of a solid lens and a liquid lens, the optical lens vertical plane position (XY) displacement is given as the relative state of the solid lens and the liquid lens. As a result, frame adjustment of the focused spot is performed.
As an observation method, coma aberration, a spot image condensed on the disk surface, or the like may be used. It is only necessary to aim for the minimum value of the coma aberration, and it is sufficient to minimize the side lobe component for the spot (step 406). In step 406, not only the objective lens but also coma aberration that the incident beam already has can be corrected. For example, the coma remaining in the transmitted beam in step 402 can also be reduced here.
The liquid lens is cured at the above-described liquid lens best position (XY). If a resin that cures by UV (ultraviolet) irradiation is used as the liquid lens, the liquid lens unit is irradiated from the outside by a UV exposure machine, and if a thermosetting resin is used, the liquid lens unit is heated by a heater or the like. That's fine.
In general, in the optical recording medium 4008, the distance between the objective lens 4007 and the optical recording medium 4008 is not constant due to vibration from the outside or touching itself. However, in order to increase the storage density on the optical recording medium 4008, it is necessary to accurately focus the spot on the optical recording medium 4008. In the optical path of the reflected light from the optical recording medium 4008, there is provided a detection lens 4009 on which a convex lens surface for collecting the reflected light to the light receiving element 4010 and a cylindrical lens surface for giving astigmatism to the reflected light are formed. Yes. When the position of the optical recording medium 4008 is deviated from the position of the image of the semiconductor laser 4001 connected by the objective lens 4007, a deviation occurs between the position of the light receiving element 4010 and the reflected light condensing position, and the spot shape on the light receiving element 4010 is changed. It changes because astigmatism is given by the cylindrical lens. A change in the spot shape on the light receiving element 4010 is detected by a known method, detected as a focus error signal, and the position of the objective lens 4007 is corrected based on the focus error signal. Thus, the optical recording medium 4008 is always controlled to be positioned at the position of the image of the semiconductor laser 4001 connected by the objective lens 4007. In order to perform the above operation, the light receiving element 4010 must be accurately positioned in a conjugate position with the semiconductor laser 4001.

In this embodiment, a combination of a solid lens and a liquid lens is used as the lens 4009. Therefore, the light receiving element 4010 is positioned at a conjugate position of the semiconductor laser 4001 by changing the focal length of the liquid lens instead of the lens interval. The adjustment is made at the time of assembling the optical pickup device.
The light receiving element has a plurality of segments (not shown), and a predetermined light quantity distribution needs to be incident on each segment. For this, the liquid lens is a relative state between the solid lens and the liquid lens. By controlling the beam direction after transmission by giving a displacement (XY) in the vertical plane of the optical axis, it is possible to allocate a desired light quantity to each segment of the light receiving element.
These adjustments may be made while detecting the reflected light from the optical recording medium 4008 so that the signal becomes the best. For example, after roughly adjusting the lens cell 4014a and the light receiving element holder 4015a so that the signal light quantity becomes maximum, the focus signal amplitude and the track error signal amplitude become maximum and the offset becomes zero while actually applying servo. Just drive into the position.
The liquid lens is cured at the liquid lens position (XY) and the focal length in the above-described best signal state. If a resin that cures by UV (ultraviolet) irradiation is used as the liquid lens, the liquid lens unit is irradiated from the outside by a UV exposure machine, and if a thermosetting resin is used, the liquid lens unit is heated by a heater or the like. That's fine.

FIG. 25 is a block diagram of an optical information processing apparatus according to an embodiment. This optical information processing apparatus is an apparatus for recording and reproducing information signals with respect to the optical recording media of the first to third embodiments, and is configured to include 9001 corresponding to the optical pickup described above. Has been. A spindle motor 9008 for rotating the optical recording medium 9007, an optical pickup 9001 used for recording and reproducing information signals, and a feed motor 9002 for moving the optical pickup 9001 to the inner and outer circumferences of the optical recording medium 9007. A modulation / demodulation circuit 9004 that performs predetermined modulation and demodulation processing, a servo control circuit 9003 that performs servo control of the optical pickup 9001, and a system controller 9006 that performs overall control of the optical information processing apparatus.
Next, the operation will be described. The spindle motor 9008 is driven and controlled by a servo control circuit 9003 and is driven to rotate at a predetermined rotational speed. In other words, the optical recording medium 9007 to be recorded and reproduced is chucked on the drive shaft of the spindle motor 9008 and rotated at a predetermined rotational speed by the spindle motor 9008 driven and controlled by the servo control circuit 9003. .
Further, as described above, the optical pickup 9001 irradiates laser light to the optical recording medium 9007 that is rotationally driven and detects the return light when recording and reproducing information signals on the optical recording medium. This optical pickup 9001 is connected to a modulation / demodulation circuit 9004. When recording an information signal, a signal input from the external circuit 9005 and subjected to predetermined modulation processing by the modulation / demodulation circuit 9004 is supplied to the optical pickup 9001. The optical pickup 9001 irradiates the optical recording medium 9007 with laser light that has been subjected to light intensity modulation, based on the signal supplied from the modulation / demodulation circuit 9004. Further, when reproducing the information signal, the optical pickup 9001 irradiates the rotationally driven optical recording medium 9007 with a laser beam having a constant output, and a reproduction signal is generated from the return light. The reproduction signal is supplied to the modem circuit 9004.
The optical pickup 9001 is also connected to a servo control circuit 9003. Then, as described above, the focus servo signal and the tracking servo signal are generated from the return light reflected and returned by the rotationally driven optical recording medium 9007 at the time of recording / reproducing the information signal. It is supplied to the control circuit 9003.

The modem circuit 9004 is connected to the system controller 9006 and the external circuit 9005. When recording an information signal on the optical recording medium 9007, the modulation / demodulation circuit 9004 receives a signal to be recorded on the optical recording medium 9007 from the external circuit 9005 under the control of the system controller 9006. Apply modulation processing. The signal modulated by the modem circuit 9004 is supplied to the optical pickup 9001. Further, when reproducing the information signal from the optical recording medium 9007, the modem circuit 9004 receives the reproduction signal reproduced from the optical recording medium 9007 under the control of the system controller 9006, and receives the reproduction signal. Is subjected to predetermined demodulation processing. The signal demodulated by the modem circuit 9004 is output from the modem circuit 9004 to the external circuit 9005.
The feed motor 9002 is for moving the optical pickup 9001 to a predetermined radial position of the optical recording medium 9007 when recording and reproducing information signals, and is based on a control signal from the servo control circuit 9003. Driven. That is, the feed motor 9002 is connected to the servo control circuit 9003 and is controlled by the servo control circuit 9003.
The servo control circuit 9003 controls the feed motor 9002 so that the optical pickup 9001 is moved to a predetermined position facing the optical recording medium 9007 under the control of the system controller 9006. The servo control circuit 9003 is also connected to a spindle motor 9008 and controls the operation of the spindle motor 9008 under the control of the system controller 9006. That is, the servo control circuit 9003 controls the spindle motor 9008 so that the optical recording medium 9007 is rotationally driven at a predetermined rotational speed when information signals are recorded and reproduced on the optical recording medium 9007.
The servo control circuit 9003 is also connected to the optical pickup 9001. When recording and reproducing information signals, the servo control circuit 9003 receives a reproduction signal and a servo signal from the optical pickup 9001, and is mounted on the optical pickup 9001 based on the servo signal. The focus servo and tracking servo are controlled by the two-axis actuator 9016.

As described above, according to the present invention, the collimating lens or the objective lens mounted on the optical pickup includes a solid lens formed of resin or glass, a plurality of electrodes, an insulating layer, and an ultraviolet ray cured on one surface of the solid lens. Type or thermosetting type conductive liquid droplets are stacked in order, so as an optical pickup for recording or reproducing information on an optical recording medium, without a mechanical adjustment mechanism, Since the aberration of the spot condensed by the objective lens can be suppressed, the optical pickup can be reduced in size and thickness.
Moreover, since the collimating lens is composed of a liquid lens, it is not necessary to adjust the position of the light source, the optical adjustment of the collimating lens can be electrically performed from the outside, and the light source and the collimating lens can be directly fixed to the housing. Therefore, no holder or cell is required.
Further, since the detection lens is composed of a liquid lens, optical adjustment of the detection lens can be electrically performed from the outside, and a cell is unnecessary because the detection lens can be mechanically fixed directly to the housing. .
Further, since the liquid lens is arranged so as to cover the conductive liquid without being mixed with the conductive liquid and with the refractive index different from that of the conductive liquid, the conductive liquid is sealed with the insulating liquid. And stable operation can be guaranteed.
Further, as an assembling method of the optical pickup, it is possible to suppress the astigmatism of the spot collected by the objective lens or the astigmatism of the beam before entering the objective lens without using a mechanical adjustment mechanism. More specifically, a mechanical member for adjusting the position of a unit composed of a semiconductor laser, a collimating lens, or a unit composed of a semiconductor laser and a collimating lens becomes unnecessary. For this reason, the optical pickup can be reduced in size and thickness. Further, the assembly equipment for position adjustment of the unit composed of the semiconductor laser, the collimator lens, or the unit composed of the semiconductor laser and the collimator lens becomes unnecessary, and the assembly equipment can be reduced.

Further, as an assembly method of the optical pickup, the coma aberration of the spot condensed by the objective lens can be suppressed without involving a mechanical adjustment mechanism. More specifically, a mechanical member for adjusting the tilt of the objective lens is not necessary. For this reason, the optical pickup can be reduced in size and thickness. In addition, the objective lens tilt adjustment assembly facility becomes unnecessary, and the assembly facility can be reduced.
Further, as an assembling method of the optical pickup, the spot on the light receiving element condensed by the detection lens can be optimized without a mechanical adjustment mechanism. More specifically, a mechanical member for adjusting the position of the detection lens becomes unnecessary. For this reason, the optical pickup can be reduced in size and thickness. Furthermore, the installation facility for adjusting the detection lens position is not necessary, and the assembly facility can be reduced.
In addition, since an optical pickup configured in a small size is mounted, for example, it is difficult to mount the optical pickup in a half-height or notebook PC application.

It is a figure explaining a general liquid lens. It is a figure explaining the angle between an insulating layer and a droplet, and an electrocapillary phenomenon. It is sectional drawing of the lens which concerns on one Embodiment of this invention. It is a figure explaining the division | segmentation pattern of the transparent electrode formed in both surfaces of the glass substrate of this invention. It is a figure explaining the focal distance change of a liquid lens. It is a figure which shows a mode that the liquid lens was seen from the electrode upper surface. It is a figure explaining the optical-axis vertical in-plane movement of a liquid lens part. It is a figure which shows a mode that the liquid lens was seen from the electrode upper surface. It is a figure explaining the optical-axis vertical in-plane movement of a liquid lens part. It is a figure which shows a mode that the liquid lens was seen from the electrode upper surface. It is another block diagram of a liquid lens. It is another block diagram of a liquid lens. It is a figure which shows the condensing characteristic of the lens which concerns on one Example of this invention. It is a figure which shows the numerical data of the lens of FIG. It is a figure which shows the focal distance change of the lens Example. It is a figure which shows the coma aberration change of a lens Example. It is a figure which shows the inclination-angle change of a lens Example. It is a figure which shows a mode that the divergent beam from a light source is converted into parallel light. 1 is a configuration diagram of an optical pickup according to a first embodiment of the present invention. It is an assembly flow diagram of the optical pickup according to the first embodiment of the present invention. It is an optical pick-up block diagram which concerns on the 2nd Embodiment of this invention. It is an assembly | attachment flowchart of the optical pick-up concerning the 2nd Embodiment of this invention. It is an optical pick-up block diagram which concerns on the 3rd Embodiment of this invention. It is an assembly | attachment flowchart of the optical pick-up concerning the 3rd Embodiment of this invention. It is a block diagram of the optical information processing apparatus which concerns on one Embodiment. It is a block diagram of the conventional optical pick-up. It is an assembly flow diagram of a conventional optical pickup. It is a figure which shows the package structure of a general semiconductor laser. It is a figure which shows the image height characteristic of an objective lens. It is a block diagram of an actuator.

Explanation of symbols

  2001 Semiconductor laser, 2002 Collimate lens, 2003 Beam shaping prism, 2004 Polarization beam splitter, 2005 1/4 wavelength plate, 2006 Deflection mirror, 2007 Objective lens, 2008 Optical recording medium, 2009 Detection lens, 2010 Light receiving element

Claims (9)

A light source, a collimating lens for converting divergent light emitted from the light source into parallel light, an objective lens for condensing a light beam on the optical recording medium, and a light receiving element for detecting reflected light from the optical recording medium, In an optical pickup equipped with
At least one of the collimating lens and the objective lens is formed by sequentially laminating a plurality of electrodes, an insulating layer, and an ultraviolet curable or thermosetting conductive liquid on one surface of a solid lens made of resin or glass. An optical pickup comprising a liquid lens.   When the collimating lens is constituted by the liquid lens, the light source and the collimating lens are directly fixed to the housing of the optical pickup, thereby eliminating the need for a holder for fixing the light source and a cell for adjusting the collimating lens. The optical pickup according to claim 1. A light source, a collimating lens for converting divergent light emitted from the light source into parallel light, an objective lens for condensing a light beam on the optical recording medium, and a light receiving element for detecting reflected light from the optical recording medium, In an optical pickup comprising: a detection lens that is disposed between the objective lens and the light receiving element and collects reflected light from the optical recording medium toward the light receiving element.
At least one of the collimating lens, the objective lens, and the detection lens includes a plurality of electrodes, an insulating layer, and an ultraviolet curable or thermosetting conductive liquid on one surface of a solid lens formed of resin or glass. An optical pickup comprising: a liquid lens in which are sequentially stacked.   4. When the detection lens is constituted by the liquid lens, a cell for adjusting the detection lens is unnecessary by directly fixing the light source and the detection lens to a housing of the optical pickup. The optical pickup described in 1.   5. The liquid lens is disposed so that an insulating liquid having a different refractive index covers the conductive liquid without mixing with the conductive liquid. The optical pickup described in 1. An adjustment method for an optical pickup according to any one of claims 1 to 5,
When the collimating lens is composed of the liquid lens, the adjustment of the collimating lens is performed by selectively changing a voltage value between each segment of the conductive liquid and the plurality of electrodes, so that the conductive liquid and the solid lens are adjusted. The astigmatism amount of the objective lens incident beam is adjusted by changing the contact angle between the contact surface with the lens, and the objective lens incident beam is tilted by changing the position in the optical axis vertical plane of the conductive liquid. An adjustment method, which is carried out by curing the conductive liquid by ultraviolet irradiation or heating in the adjusted state. An adjustment method for an optical pickup according to any one of claims 1 to 5,
When the objective lens is constituted by the liquid lens, the tilt adjustment of the objective lens is performed by selectively changing a voltage value between each segment of the conductive liquid and the plurality of electrodes. The adjustment is performed by curing the conductive liquid by ultraviolet irradiation or heating in a state where the amount of coma of the spot image collected by the objective lens is adjusted while changing the position in the plane perpendicular to the optical axis. Method. An adjustment method for an optical pickup according to any one of claims 1 to 5,
When the detection lens is constituted by the liquid lens, the adjustment of the detection lens is performed by selectively changing a voltage value between each segment of the conductive liquid and the plurality of electrodes, so that the conductive liquid and the solid lens are adjusted. While changing the contact angle between the contact surface with the lens and the position in the optical axis vertical plane of the conductive liquid, the track error signal or the focus error signal is adjusted so that the amplitude value of the focus error signal is substantially maximized. An adjustment method characterized in that the conductive liquid is cured by ultraviolet irradiation or heating.   An optical information processing apparatus for recording or reproducing information on an optical recording medium, wherein the optical information processing apparatus includes the optical pickup according to any one of claims 1 to 5. An optical information processing apparatus.

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