KR20040055232A - Optical pick-up head of optical recorder, manufacturing method thereof - Google Patents

Abstract

PURPOSE: An optical pickup head and its producing method are provided to compensate for a variation of a gap between a record layer and a pickup head in order to optimally focus on a record layer. CONSTITUTION: The system comprises a slider(100), and a main body(200). The slider(100) includes a convergence lens facing a disc surface. The main body(200) includes an object lens(60) arranged on an optical axis for transmitting a beam from a beam transceiver to the convergence lens. The slider(100) includes a base plate(101), a convergence lens(102), a magnetic field generation coil(103), a pneumatic pressure generator(104), and an arrangement mark(106). The convergence lens(102), protruded from the base plate(101), has a semispherical shape. The magnetic field generation coil(103) has a center on an optical axis of the convergence lens. The pneumatic pressure generator(104) is arranged under the base plate(101). The arrangement mark is on the base plate(101).

Description

Optical pickup head of optical recording and reproducing apparatus, manufacturing method thereof {OPTICAL PICK-UP HEAD OF OPTICAL RECORDER, MANUFACTURING METHOD THEREOF}

The present invention relates to an optical pickup head of an optical recording and reproducing apparatus.

By minimizing signal degradation due to focal distortion due to variations in the protective layer thickness formed on the recording layer of the optical disc having the surface recording method, and a change in focal depth during operation due to incomplete disk flatness, An optical head device having a slide type slider for maintaining an optimal signal to noise ratio.

The sliding optical pick-up head of the high-density optical recording and reproducing apparatus according to the present invention is a pneumatic floating slider having sliding performance, magneto-optical recording function, and focusing lens function, and a vertical lens for driving an objective lens. It consists of a driver and an objective lens or the like mounted on the driver, the manufacturing method of the optical pickup head according to the present invention proposes a method for manufacturing the above structure more efficiently.

With the recent development of the multimedia environment, generalization of personal computers, generalization of data networks, and advances in wireless communication technologies, the universalization of mobile communication means such as personal information terminals and video telephones has been processed in these devices. This entailed a significant increase in the amount of information to be processed / stored.

In addition, in order to meet the demand of a small, lightweight and large-capacity information storage device suitable for such a portable device, it is essential to miniaturize the optical information storage device with a dramatic increase in the information recording density.

In response to this, various studies have been conducted to increase the recording density of optical recording media such as CDs and DVDs, to increase the resolution of optical pickup devices, and to implement optical components having smaller form factors.

On the other hand, the required performance of a large-capacity information storage device includes not only high recording density but also high speed of data access speed for rapid recording and reproducing of information.

As one of the optical pickup devices that can satisfy the requirements of the ultra-high density optical recording and reproducing apparatus, a sliding optical pickup slider head capable of recording / reproducing / searching arbitrary data on the optical disk using aerodynamic flotation is used. Can be.

In order to maintain the gap with the optical disk by such a slide type slider structure, the functional structure of the slider that can secure a hydrodynamically stable flotation force is very important.

This functional structure includes an air-bearing surface (ABS) pattern formed on the slider surface facing the disk substrate, and a tapered edge structure in which the front portion of the slider surface is processed at a constant angle or stepped successively. For example.

On the other hand, the alignment error between the ABS lens pattern and the position of the focusing lens mounted on the floating slider to focus the input laser beam on the recording layer of the optical disk has the uniformity and reliability of the optical information signal recorded and reproduced on the optical disk surface. This is an important tolerance for determining reliability and resolution.

Errors in the alignment and assembly steps include, for example, shifts parallel to the slider surface direction, focal length errors perpendicular to the slider surface direction, and tilted errors in the front, rear, and left and right directions of the SIL. Can be.

However, in the related art, a method of constituting an optical pick-up head by using a focusing lens, a slider component including the ABS pattern, an objective lens, and an optical pick-up head main body independently processed / manufactured and aligned / assembled is used.

This method inevitably leads to deterioration of the performance of the optical recording / reproducing apparatus employing the pickup slider manufactured by the method by making the alignment and assembly error inevitable.

In addition, the conventional slider manufacturing method is dependent on the polishing and cutting process, so that the mass production of the slider parts is low, the uniformity between the elements is not only reduced, and the yield is significantly low, which increases the cost of the parts. .

SUMMARY OF THE INVENTION The present invention solves the above problems, such as uneven protective layer thickness on the recording layer, flatness error of the disk surface, uneven disk thickness, and the like, including processing tolerances in optical disk manufacturing and errors occurring in assembling and mounting. Due to the shape error and the unevenness of the optical disk surface caused by the eccentricity and vibration of the rotating shaft of the spindle motor for mounting and rotating the disk, thereby correcting the change in the gap between the recording layer and the pickup head. Optimal focus is ensured on the recording layer.

1 to 10 show an embodiment of the present invention,

1 is an exploded perspective view

2 is a plan view

3 is a cross-sectional view taken along the line A-A of FIG.

4 is a partial perspective view showing an electrode arrangement structure

5 is a plan view showing the electrode arrangement structure

6 is a cross-sectional view showing the electrode arrangement structure

7 is an exploded perspective view

8 to 10 is a conceptual diagram showing a principle of focus depth correction

** Description of the symbols for the main parts of the drawings **

11: upper substrate 12: lower substrate

13: insulation layer 21: upper fixed electrode

22: lower fixed electrode 23: movable electrode

30: movable substrate 31: elastic support

60: objective lens 100: slider

101: substrate portion 102: focusing lens portion

103: magnetic field generating coil 104: air pressure generating unit

200: optical pickup head body 400: disc

401: substrate 402: recording layer

403: protective layer

In order to achieve the object described above, the present invention provides a slider equipped with a focusing lens that is opposed to a disk surface, and a main body equipped with an optical lens aligned with an optical axis aligned to transmit light transmitted from the transmitting and receiving unit to the focusing lens. In addition, in the optical pickup head of the optical recording and reproducing apparatus for recording or reproducing information by injecting light into the recording layer of the disk through the focusing lens, the slider is a substrate portion formed of a transparent substrate structure; ; A focusing lens portion protruding in a partial spherical shape on the upper surface of the substrate portion; A magnetic field generating coil installed in a circumferential shape so that the optical axis and the central axis thereof coincide with the focusing lens unit; An air pressure generating portion formed on the bottom surface of the substrate portion; An alignment mark formed on an upper surface of the substrate portion; The optical pickup head body includes: a substrate portion having an objective lens mounting hole formed at a core portion thereof; An alignment mark formed on a lower surface of the substrate portion and formed to face an alignment mark of the slider; Objective lens fine driving means for finely driving the objective lens mounted in the objective lens mounting hole along the optical axis; An optical pickup head of an optical recording and reproducing apparatus is configured to include.

In addition, the anti-reflective coating film is formed on the focusing lens unit.

In addition, it is preferable that a protective layer or a lubrication layer is formed on the bottom of the air pressure generating unit.

In addition, the objective lens micro-driving means includes an upper substrate having a movable substrate driving hole in the core portion; An upper fixed electrode formed on an inner circumference of a driving hole of the upper substrate; An insulating layer coupled to a lower portion of the upper substrate, the movable substrate driving hole being formed in a core at a position corresponding to the movable substrate driving hole; A lower substrate coupled to a lower portion of the upper substrate, the movable substrate driving hole being formed in a core at a position corresponding to the movable substrate driving hole; A lower fixed electrode formed on an inner circumference of a driving hole of the lower substrate; A movable substrate formed with a core in the objective lens mounting hole, positioned in the movable substrate driving hole, and coupled by the substrate and the elastic support portion; A movable electrode formed at a position corresponding to the fixed electrode as an outer peripheral portion of the movable substrate; A fixed electrode pad mounted to the substrate to apply power to the fixed electrode; A movable electrode pad mounted to the substrate to apply power to the movable electrode; It is preferable to include.

On the other hand, the present invention provides a method for manufacturing the optical pickup head which is another means for achieving the above object, the method comprising the steps of manufacturing the slider and the body in the form of each component by micromachining and semiconductor device integrated manufacturing process, respectively; Aligning and bonding the manufactured slider and the main body using the alignment mark; Installing the objective lens so that the optical lens is aligned with the focus lens unit; A method of manufacturing an optical pickup head of an optical recording and reproducing apparatus is provided.

In addition, the method of manufacturing the optical pickup head comprises the steps of manufacturing the slider and the body in the form of a wafer by a micromachining and semiconductor device integrated manufacturing process, respectively; Aligning and bonding the manufactured slider wafer and the main wafer using the alignment mark; Cutting the bonded wafer for each component; Installing the objective lens so that the optical lens is aligned with the focus lens unit; It may be configured to include.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 to 10 show an embodiment of the present invention, Figure 1 is an exploded perspective view, Figure 2 is a plan view, Figure 3 is a AA cross-sectional view of Figure 2, Figure 4 is a partial perspective view showing the electrode arrangement structure, Figure 5 6 is a plan view illustrating an electrode arrangement structure, FIG. 6 is a cross-sectional view illustrating an electrode arrangement structure, FIG. 7 is an exploded perspective view, and FIGS. 8 to 10 are conceptual views illustrating a principle of focus depth correction.

As shown, the optical pickup head of the optical recording and reproducing apparatus according to the present invention is basically transmitted from the slider 100 equipped with a focusing lens facing the surface of the disk 400 and from a transmitter / receiver (not shown). The main body 200 is equipped with an objective lens aligned with an optical axis to transmit the light to the focusing lens, and inputs light to the recording layer 402 of the disc through the focusing lens to record or reproduce information. It is the same as a conventional structure in the point.

However, the slider 100 includes a substrate portion 101 formed of a transparent substrate structure; A focusing lens portion 102 protruding in a partial spherical shape on the upper surface of the substrate portion 101; A magnetic field generating coil (103) provided in a circumferential form in the vicinity of the focusing lens unit (102) so that its optical axis and its central axis coincide with each other; An air pressure generating unit 104 formed on a lower surface of the substrate unit 101; An alignment mark (106) formed on an upper surface of the substrate portion (101); The optical pickup head main body 200 includes: substrate parts 11 and 12 having objective lens mounting holes formed at core portions thereof; An alignment mark (not shown) formed on the lower surface of the substrate portions (11, 12) and formed to abut against the alignment mark (106) of the slider (100); Objective lens micro-driving means for finely driving the objective lens 60 mounted in the objective lens mounting hole along the optical axis; It is characterized in that it is configured to include.

That is, in the related art, a method of constituting an optical pickup head by using a focusing lens, a slider component including the ABS pattern, an objective lens, and an optical pickup head main body independently processed / manufactured and aligned / assembled is used. Although a problem that an error cannot be avoided has been pointed out, the optical pickup head according to the present invention integrally forms the substrate portion 101 and the focusing lens portion 102 of the slider 100, and includes an objective lens micro-driving means thereon. After the main body 200 is aligned / assembled by the alignment mark 106, the objective lens 60 is aligned with the optical axis of the focusing lens unit 102. Can be reduced.

The present invention focuses on the fact that the entire area of the cross section of the focusing lens is not necessarily required for focusing light, and a partially spherical projecting focusing lens part 102 is formed in the area required for focusing light, and the remaining area is By configuring the main body of the slider 100, it is possible to obtain a simple and economical integrated slider structure.

Such a structure may be implemented by a micromachining and a semiconductor device integrated manufacturing process, the processing of the substrate portion 101 by deep reactive ion etching technology, or anisotropic etching technology or the like The surface of the substrate can be realized by precise processing, and the curved processing of the protruding focusing lens unit 102 is a reflow technique using the surface tension of the photoresist film, and a gray scale photo patterned by replacing the curved surface of the photoresist film with a plurality of step shapes. Gray-tone lithography and their complex techniques can be easily implemented.

The protruding focusing lens unit 102 should allow the light incident from the transmitter / receiver (not shown) to pass through without reflection and reach the recording layer 402 of the disk 400, so that an antireflective coating film is formed on the surface thereof. desirable.

In addition, it is preferable that a protective layer or a lubrication layer is formed on the bottom of the air pressure generating unit 104 to exclude heat, contamination and other harmful effects due to friction with the disk surface.

Hereinafter, the objective lens fine driving means will be described.

The objective lens micro-driving means formed in the main body 200 of the optical pickup head according to the present invention comprises: an upper substrate 11 having a movable substrate driving hole in a core portion thereof; An upper fixed electrode 21 formed on an inner circumference of a driving hole of the upper substrate; An insulating layer (13) formed at a core at a position corresponding to the movable substrate driving hole and coupled to a lower portion of the upper substrate (11); A lower substrate 12 having a movable substrate driving hole formed at a core at a position corresponding to the movable substrate driving hole and coupled to a lower portion of the upper substrate 11; A lower fixed electrode 22 formed in the inner circumferential portion of the lower substrate 12; An objective lens mounting hole 33 is formed in the core portion, the movable substrate 30 being positioned inside the movable substrate driving hole and coupled by the substrates 11 and 12 and the elastic support part 31; A movable electrode 23 formed at a position corresponding to the fixed electrodes 21 and 22 as an outer peripheral portion of the movable substrate 30; Fixed electrode pads 41 and 42 mounted to the substrates 11 and 12 to apply power to the fixed electrodes 21 and 22; Movable electrode pads 50 mounted to the substrates 11 and 12 to apply power to the movable electrodes 23; An objective lens 60 mounted in the objective lens mounting hole 33; It is configured to include.

The fixed electrodes 21 and 22 and the movable electrode 23 have a structure in which a plurality of comb-shaped electrodes are opposed to each other at predetermined intervals.

The objective lens 60 is mounted in the objective lens mounting hole 33 of the movable substrate 30 of the electrostatic force bidirectional fine driver having precision driving characteristics in the optical axis direction of the lens, and the movable substrate 30 is in the driving direction thereof. It is suspended on the substrates 11 and 12 by the elastic support part 31 which is elastic with respect to.

The displacement of the movable substrate 30 is controlled by controlling the electrostatic forces induced by the comb-shape microelectrode arrays 21, 22, 23 formed on the substrates 11, 12 and the movable substrate 30, respectively. I can regulate it.

The electrostatic force for driving can be obtained by applying a predetermined driving voltage between the movable electrode 23 formed on the movable substrate 30 and the fixed electrodes 21, 22 formed on the substrates 11, 12. It is applied through the electrode pads (41, 42, 50) formed to be electrically connected to each drive electrode of the comb-shaped bidirectional drive electrode array (21, 22, 23).

The objective lens 60 is mounted on the support jaw 32 formed on the movable substrate 30 in a passive alignment manner. In addition, a through hole 33 is formed under the clear aperture of the focusing lens 60 so as to secure an optical path.

The movable substrate 30 is suspended on the substrates 11 and 12 by the elastic support 31 and is positioned at a predetermined point between the upper substrate 11 and the lower substrate 12.

The upper substrate 11 and the lower substrate 12 are divided by an insulating layer 13 composed of an electrical insulator. Such a structure is commercialized in the form of a silicon on insulator (S.O.I.) wafer, and can be easily implemented in other manufacturing processes.

As shown in FIGS. 4 to 6, the fixed electrodes 21 and 22 and the movable electrode 23 use three electrically insulated electrode structures unlike the conventional simple bipolar comb-drive electrodes.

That is, the comb-tooth shaped electrodes connected to the substrates 11 and 12 are formed by dividing the upper fixed electrode 21 and the lower fixed electrode 22 by the inter-electrode insulating layer 24 in the middle. Repeated in the plane direction.

A movable electrode 23 connected to the movable substrate 30 is formed between the protruding fixed electrodes 21 and 22.

The movable electrodes 23 and the fixed electrodes 21 and 22 are spaced apart by air or free space, and the separation distance 25 determines the electrostatic force generation efficiency with respect to the applied voltage.

As shown in FIG. 7, the assembly of the focusing lens 60 is performed by coupling the protruding jaw 61 of the focusing lens 60 to the support 32 of the movable substrate 30. That is, when the focusing lens 60 is mounted on the movable board 30, the direction in which gravity acts on the movable board 30 released by the load of the focusing lens 60 and the movable board 30 itself. The relative position of the electrode array may be configured using this.

The optical pickup head according to the present invention is manufactured by aligning / assembling the slider 100 and the main body 200 having the above-described structure.

First, after the slider 100 and the main body 200 are manufactured in the form of each component by micromachining and a semiconductor device manufacturing process, respectively, the slider 100 and the main body 200 are manufactured by the alignment mark 106. And the objective lens 60 is aligned with the focusing lens unit 102 so as to align the optical axis.

Second, after the slider 100 and the main body 200 are manufactured in a wafer form by micromachining and a semiconductor device manufacturing process, the slider wafer and the main body wafer are aligned and aligned using the alignment mark 106. Bonding, cutting the bonded wafer for each component, and arranging the objective lens 60 to align the optical lens with the focusing lens unit.

This alignment bonding technique uses anodic bonding technique with a silicon substrate to form the main body 200 when the substrate constituting the focusing lens is a glass substrate containing impurities such as sodium (for example, pyrex # 7740). Can be.

On the bottom of the slider 100 is integrated an air-bearing surface 104 capable of generating aerodynamic buoyancy from the rotating optical disk 400 surface, with a direct overwriting function. The magnetic field generating coil 103 is integrated and integrated in a circumferential shape so that the optical axis and the central axis of the focusing lens unit 102 coincide with each other in an etching groove in which the focusing lens unit 102 is formed.

The magnetic field generating coil 103 may be integrated on the surface where the focusing lens unit 102 is processed, or may be embedded in the rear surface of the magnetic field generating coil 103. By allowing a proportional magnetic field to occur in the direction of the optical axis, it is possible to change the magnetic polarization of the magneto-optical material, which is the recording layer of the disc, thereby making it possible to record and rewrite the information (re-writable).

8 to 10, the operation of adjusting the depth of focus of the optical pickup head according to the present invention will be described in more detail.

8 shows a case in which the thickness of the protective layer 403 on the recording layer 402 of the optical disk coincides with the ideal design value in the optical design, and there is no thickness error and the laser beam incident from the outside is also ideal parallel light.

In such an ideal situation, even if the optical signal is recorded and reproduced at a null position without driving the objective lens 60, the focus of the laser beam is formed on the recording layer 402 of the optical disk 400 that is rotated correctly. Degredation of the optical signal does not occur and stable operation is performed.

In the figure, g is the distance between the surface of the protective layer 403 and the bottom of the slider 100, t ₀ is the ideal protective layer thickness within the tolerance range in the optical design, l ₀ is the objective lens 60 and the focusing lens. Distance between parts 102.

FIG. 9 illustrates a case in which the thickness t ₁ of the protective layer 403 of the optical disk 400 is thinner than the allowable processing tolerance when designing the optical system. The laser beam is incident by the depth of focus adjustment function of the optical pickup head according to the present invention. An example of a driving state in which the focus is at the recording layer 102 is illustrated.

As shown, the objective lens 60 is moved upward by the fine driving means to increase the distance l ₁ , and accordingly the focal length from the bottom of the slider 100 is shortened to correct the thinner protective layer thickness. The state illustrates the situation.

If the rotational speed or rotational speed of the optical disk 400 is the same, even if the protective layer thickness is thin, the gap in which the optical pickup head floats from the surface of the disk does not change the floating height g that slides on the optical disk having the ideal protective layer thickness. The change in the focal length to be corrected by the objective lens fine driving means may be enough to offset the change portion of the protective layer thickness t ₁ .

10 shows the case where the protective layer thickness t ₂ is thicker than the ideal design dimension. In this case, the distance l ₂ between the two lenses is determined by bringing the position of the objective lens 60 close to the focusing lens portion 102 of the slider 100. The fine driving means may be adjusted so as to reduce the depth of focus from the focusing lens unit 102.

The optimal position of the objective lens driven by the micro-driving means is reflected by the recording layer 402 so that the optical signal detector and the optical signal of the optical focusing servo detector of the transmitter / receiver (not shown) are determined under the condition of detecting the optical signal of a predetermined level. The driver input stage is controlled by a negative feedback circuit.

Similarly, the error of incident collimation parallel light due to the assembly error of the independent optical system and the shape error and performance error of each optical element is also fine driving means so that the recording layer detail optical signal can be maintained optimally by the negative feedback servo circuit. Depth of focus correction is performed.

The present invention provides a shape error due to a nonuniform protective layer thickness on a recording layer, a flatness error on the surface of a disc, an uneven disc thickness, and the like, including processing tolerances in optical disk manufacturing and errors occurring during assembling and the like, and mounting a disc. Spindle motor to rotate the spindle motor to compensate for variations in the gap between the recording layer and the pickup head, which are unavoidable due to the unevenness of the optical disk surface caused by the eccentricity and vibration of the rotating shaft. Make it happen.

Claims (6)

And a main body equipped with a slider equipped with a focusing lens opposed to a surface of the disk and an objective lens aligned with an optical axis to transmit light transmitted from the light-receiving portion to the focusing lens. An optical pickup head of an optical recording / reproducing apparatus for recording or reproducing information by injecting light into a recording layer, The slider is A substrate portion formed of a transparent substrate structure; A focusing lens portion protruding in a partial spherical shape on the upper surface of the substrate portion; A magnetic field generating coil installed in a circumferential shape so that the optical axis and the central axis thereof coincide with the focusing lens unit; An air pressure generating portion formed on the bottom surface of the substrate portion; An alignment mark formed on an upper surface of the substrate portion; Is configured to include, The optical pickup head body A substrate portion in which an objective lens mounting hole is formed in the core portion; An alignment mark formed on a lower surface of the substrate portion and formed to face an alignment mark of the slider; Objective lens fine driving means for finely driving the objective lens mounted in the objective lens mounting hole along the optical axis; The optical pickup head of the optical recording and reproducing apparatus, characterized in that it comprises a. The method of claim 1, The optical pickup head of the optical recording and reproducing apparatus, characterized in that the anti-reflection coating film is formed on the focusing lens unit. The method of claim 1, And a protective layer or a lubricating layer formed on a bottom surface of the air pressure generating unit. The method of claim 1, The objective lens fine driving means An upper substrate having a movable substrate driving hole formed in the core portion; An upper fixed electrode formed on an inner circumference of a driving hole of the upper substrate; An insulating layer coupled to a lower portion of the upper substrate, the movable substrate driving hole being formed in a core at a position corresponding to the movable substrate driving hole; A lower substrate coupled to a lower portion of the upper substrate, the movable substrate driving hole being formed in a core at a position corresponding to the movable substrate driving hole; A lower fixed electrode formed on an inner circumference of a driving hole of the lower substrate; A movable substrate formed with a core in the objective lens mounting hole, positioned in the movable substrate driving hole, and coupled by the substrate and the elastic support portion; A movable electrode formed at a position corresponding to the fixed electrode as an outer peripheral portion of the movable substrate; A fixed electrode pad mounted to the substrate to apply power to the fixed electrode; A movable electrode pad mounted to the substrate to apply power to the movable electrode; And an optical pickup head of an optical recording and reproducing apparatus. A method of manufacturing the optical pickup head of claim 4, Manufacturing the slider and the main body in the form of each component by micromachining and semiconductor device integrated manufacturing processes, respectively; Aligning and bonding the manufactured slider and the main body using the alignment mark; Installing the objective lens so that the optical lens is aligned with the focus lens unit; A method of manufacturing an optical pickup head of an optical recording and reproducing apparatus, comprising: A method of manufacturing the optical pickup head of claim 4, Manufacturing the slider and the main body in wafer form by micromachining and semiconductor device integrated manufacturing processes, respectively; Aligning and bonding the manufactured slider wafer and the main wafer using the alignment mark; Cutting the bonded wafer for each component; Installing the objective lens so that the optical lens is aligned with the focus lens unit; A method of manufacturing an optical pickup head of an optical recording and reproducing apparatus, comprising: