JP3517365B2 - Optical pickup device and position adjustment method of optical element thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device in which a laser beam emitted from a laser light source is focused on an optical recording medium and a return light from the optical recording medium is detected by a photodetector. More specifically, a laser light source,
The present invention relates to an optical pickup device capable of easily positioning an optical element such as a light detection element and a diffraction element, and a position adjusting method for the optical element.

[0002]

2. Description of the Related Art As an optical pickup device used for recording / reproducing optical disks such as CD, DVD, MO,
There is known a device including a light source unit in which optical elements such as a semiconductor laser, a photodetector and a hologram element are incorporated in a package. Such an optical pickup device is disclosed in, for example, Japanese Patent Laid-Open Nos. 8-124205 and 3-278330.

[0003]

In such an optical pickup device, the relative position of the semiconductor laser and the hologram element, the relative position of the reflection mirror and the photodetector, etc. have a great influence on the characteristics of the device. For example, if the relative position of the semiconductor laser and the hologram element deviates from the target one, the desired separation characteristics cannot be obtained, and the accuracy of reproduction of the optical disk and the like deteriorates. Further, if the relative position between the reflection mirror and the photodetector is deviated, the return light will not be collected at an appropriate position on the photodetector, and the accuracy of reproduction of the optical disk will also deteriorate.

Here, in the case of a light source unit in which each optical element is mounted in the package, the relative positional relationship of each optical element mounted inside cannot be adjusted after the package is sealed. Therefore, it is particularly difficult to position each optical element.

In view of the above points, an object of the present invention is to propose an optical pickup device equipped with a mechanism capable of easily adjusting the relative positions of the optical elements constituting the optical system of the optical pickup device. To do.

Another object of the present invention is to propose a position adjusting method for easily adjusting the position of each optical element in an optical pickup device having such a mechanism.

[0007]

[0008]

[0009]

[0010]

[0011]

[0012]

[Means for Solving the Problems]
Therefore , according to the present invention, a laser light source and a semiconductor substrate on which a photodetection element for detecting return light emitted from the laser light source and reflected by an optical recording medium are formed are incorporated in a common package. In the optical pickup device having a light source unit: a light passage hole for the laser light from the laser light source and the return light is formed in the package; and for guiding the return light to the photodetection element in the package. A reflector that reflects the return light is disposed in the package, and the position where the reflector is disposed is set to a position that can be exposed from the outside of the package through the light passage hole; The semiconductor device is mounted on the substrate surface of the semiconductor substrate directly or indirectly through a predetermined member; the package includes a package body to which the semiconductor substrate is attached, and And a package lid that is slidably attached to the package body in the optical axis direction of the laser light and to which the reflector is attached, and the package lid is fixed to the package body at a predetermined slide position. A positioning mark indicating a relative position to the light emitting point of the laser light source is provided on the surface of the substrate near the photodetector ;
The positioning mark is the positioning mark on the reflector.
It is characterized in that the ark is formed at a position where it can be observed through the light passage hole .

In the optical pickup device having this structure, the relative position in the optical axis direction between the detecting element mounted on the package body side and the reflector mounted on the package lid is adjusted by the following position adjusting method. can do.

First, the position of the reflector is moved by sliding the package lid while observing the light emitting point of the laser light source and the positioning mark reflected on the reflector through the light passage hole of the light source unit. adjust. Next, after adjusting the position of the reflector, the package lid is fixed to the package body with an adhesive or the like.

According to this method, the position of the optical elements attached to both members can be adjusted with the package lid assembled to the package body, and the adjustment work can be performed while observing from outside the package. It can be carried out. Therefore, the positioning of the optical element mounted in the package can be performed easily and accurately.

[0016]

[0017]

[0018]

[0019]

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical pickup device to which the present invention is applied will be described below with reference to the drawings.

(Overall Structure of Optical Pickup Device) FIG. 1 shows a schematic structure of an optical system of the optical pickup device. The optical pickup device 1 of the present example includes a light source unit 10, and the light source unit 10 has a built-in component such as a semiconductor laser as described later in detail.

The optical system of the optical pickup device 1 includes a three-beam generating diffraction element 13, a separation diffraction element 14, a rising mirror 18, and an objective lens 12, and these optical elements are the semiconductor laser 2 and the optical disk. 4 are arranged in this order. Further, a reflection mirror (reflector) 15 for guiding the return light from the optical disc 4 to the photodetecting element 3 is provided.

The forward laser light Lf emitted from the semiconductor laser 2 is incident on the three-beam generating diffraction element 13. The three-beam generating diffraction element 13 splits the forward laser light Lf from the semiconductor laser 2 into a main beam (0th order light) and two sub-beams (+ -first order light). Further, it has a function of converting the wavefronts of the two sub-beams so that the two sub-beams are focused on the front and rear in the optical axis direction on the optical disc 4.

The divided main beam is used as a laser beam for signal reproduction (laser beam for signal reproduction), and the two sub-beams are used as laser beam for tracking error detection (laser beam for tracking error detection).

The laser beam Lf is then separated by the diffraction element 14 for separation.
Reach. The diffraction characteristics of the separating diffraction element 14 are
The zero-order diffraction efficiency of the two laser beams in the optical path reaching the optical disk 4 and the 1-degree in the optical path reaching the photodetector 3 from the optical disk 4.
It is set such that the product of the second-order diffraction efficiency is maximum.
For example, the emitted laser light Lf has substantially no diffracting effect and allows the three beams to substantially pass therethrough. On the other hand, most of the return light Lr is diffracted, and there is almost no amount of light that passes as it is as the 0th order light. As a result, the return light Lr returned to the separation diffraction element 14 via the same optical path as the emission side laser light Lf is substantially separated from the laser light Lf and travels in a different direction.

The rising mirror 18 is the separation diffraction element 1
It is for bending the laser beam Lf from 4 at a right angle and guiding it to the objective lens 12. Of the laser light Lf, the main beam (signal reproduction laser light) is focused on the recording surface by the objective lens 12, and the two sub-beams (tracking error detection laser light) are in the front focus state and the rear focus state. .

On the other hand, 3 focused on the recording surface of the optical disk 4
The two laser beams are reflected there to become a return beam Lr from the optical disc 4 toward the photodetector 3. These return lights Lr are again used for the objective lens 12 and the rising mirror 18.
It is incident on the separating diffraction element 14 via the.

As described above, the separating diffraction element 14 is
Each of the three return lights Lr is diffracted, separated from the emission side laser light Lf, and guided to the reflection mirror 15. That is,
The return light Lr separated from the laser light Lf on the emission side by the separation diffraction element 14 is used as the three-beam generation diffraction element 13.
Directly to the reflection mirror 15 without passing through the diffraction grating surface. Here, in this example, each return light L
A diffraction grating pattern is formed so that r is divided into two in the direction orthogonal to the track direction of the optical disc 2 with the optical axis as the center. Therefore, the reflection mirror 15 has a total of 6
Two return lights Lr enter.

These diffracted lights are made to fall at a right angle by the reflection mirror 15 and illuminate each light receiving surface of the photodetector element 3. An RF (information reproduction) signal, a TE (tracking error) signal, and an FE (focusing error) signal are generated based on the light quantity of the light spot formed on each light receiving surface. Further, as will be described later, an objective lens movement amount detection signal indicating the movement amount of the objective lens 12 with respect to the optical axis is generated.

The rear laser beam Lb emitted from the rear surface of the semiconductor laser chip 2 is received by the monitor light receiving element 2
The amount of light is detected by 5, and based on the detection result,
The laser light output of the semiconductor laser chip 2 is feedback-controlled.

The objective lens 12 is mounted on the objective lens driving device 19. The objective lens driving device 19 is
Based on the above TE signal and FE signal, the objective lens 1
2 is moved in the tracking direction and the focusing direction. In addition, it also has a function of attenuating the shake of the objective lens 12 in the tracking direction based on the objective lens movement amount detection signal and performing feedback control so that the objective lens 12 quickly becomes stationary at the optical axis position.

(Light Source Unit) FIG. 2 (A) is a plan view of the light source unit, and FIGS. 2 (B) and 2 (C) are a sectional view taken along the line BB and C- in FIG. 2 (A), respectively. C
It is sectional drawing in a line. FIG. 3 is a front view of the light source unit as viewed from the front (direction of arrow III in FIG. 2A). Note that in FIG. 2A, a part of the package is omitted for easy understanding of the internal configuration of the light source unit.

Describing with reference to these figures, the semiconductor laser 2, the photodetector 3, the beam generating diffraction element 13 and the reflector 15 are incorporated in the light source unit 10 of this embodiment, and the package is formed. The separating diffraction element 14 is assembled on the front surface.

More specifically, the semiconductor substrate 11 and the submount 24 mounted on the substrate surface 111 of the semiconductor substrate 11 are disposed inside the package 20.
The semiconductor laser 2 is indirectly mounted on the upper surface of the submount 24, and the photodetection element 3 is formed on the substrate surface 111 of the semiconductor substrate 11. The semiconductor laser 2 is
It is also possible to mount the semiconductor substrate 11 directly on the substrate surface 111.

On the front surface 204 of the package 20, a frame-shaped projecting portion 201 projecting forward is formed, whereby a light passage hole 203 having a rectangular cross section is defined. Light passage hole 20
A three-beam generating diffractive element 13 is attached to the rear end of 3, and a separating diffractive element 14 is attached to the front surface thereof. The front laser light Lf emitted from the semiconductor laser 2 is emitted to the outside through the light passage hole 203 to which the diffractive elements 13 and 14 are attached, and the return light Lr from the optical disc 4 is introduced into the package. Get burned.

The package 20 is composed of a substantially box-shaped package body 21 having an upper opening, and a package cover plate 22 closing the upper opening. The package body 21 and the package cover plate 22 define a chamber 202 in which the semiconductor substrate 11 and the submount 24 are mounted.

FIG. 4 (A) is a plan view of the package body, and FIGS. 4 (B) and 4 (C) are respectively 4B of FIG. 4 (A).
4B is a cross-sectional view taken along line 4B and 4C-4C. As shown in these figures, the package body 21 includes a substantially rectangular bottom wall 211, a front wall 212 and a rear wall 213 that rise from four sides of the bottom wall 211.
And left and right sidewalls 214, 215. A part of the front wall 212 is cut into a concave shape, and a pair of left and right protruding side walls 216 and 217 extend perpendicularly to the front wall 212 from both sides thereof. The lower ends of the protruding side walls 216 and 217 are connected by a protruding bottom wall 218 extending forward from the bottom wall 211. The protruding side wall 216, 217 and the protruding bottom wall 218 form a protruding portion 219 protruding forward.

The surface of the bottom wall 211 of the package body 21 is flat, and the semiconductor laser 2 and the submount 24 are provided.
And a reference plane 3 for defining the position of the semiconductor substrate 11.
It is set to 0. A rectangular plate-shaped stage 231 of the lead frame 23 is fixed to the reference surface 30. 12 leads of the lead frame 23 (1 lead in this example)
The two leads) 232 have their pad portions on the reference surface 30.
And a portion that will be an external connection terminal extends through the rear wall 213 of the package body 21 to the outside.

Further, as shown in FIG. 2C or FIG. 4C, in the light source unit 10, a part of the external connection terminal 232 is exposed on the side of the bottom wall 211 where the semiconductor laser 2 is arranged. Thus, a plurality of heat dissipation openings 90 are formed. Therefore, in the light source unit 10, heat generated during operation of the semiconductor laser 2, the signal processing circuit, and the like inside the package 20 is radiated to the outside through the heat dissipation openings 90.

(Structure of Semiconductor Substrate and Its Periphery)
5 is an enlarged perspective view showing the semiconductor substrate and its peripheral portion, and FIG. 6 is a plan view showing the substrate surface of the semiconductor substrate. As shown in FIGS. 2, 5, and 6, the semiconductor substrate 11 is bonded to the stage 231 of the lead frame 23 with silver paste. Semiconductor substrate 1
On one substrate surface 111, a substantially rectangular electrode portion 111a that is long in the front-rear direction is formed on one side in the width direction, and a signal processing circuit 26 is formed on the other side. The submount 24 is fixed on the electrode portion 111a with silver paste. The submount 24 is made of a semiconductor substrate having a constant thickness, and the semiconductor laser 2 is fixed on the upper surface thereof by silver paste.

The semiconductor laser 2 has a front emission end facet 2f from which the front laser beam Lf is emitted and a rear emission end facet 2b from which the rear laser beam Lb is emitted. From the emission end faces 2f and 2b, the substrate surface 111 of the semiconductor substrate 11 is formed.
The laser beams Lf and Lb are emitted in a direction parallel to the front and rear directions, respectively. The light emitting point of the front laser light Lf of the semiconductor laser 2 is located at substantially the center in the vertical direction of the package 20 on the front emission end face 2f, and the front laser light Lf emitted from this is attached to the light passage hole 203. The light is emitted to the outside through the diffraction element 13 for beam generation and the diffraction element 14 for separation.

On the substrate surface 111 of the semiconductor substrate 11,
Signal processing circuit 2 formed on the side of the electrode portion 111a
Reference numeral 6 raises the level of the output signal of the photo-detecting element 3 to facilitate the generation processing of the pit signal (RF signal), the tracking error signal (TE signal) and the focus error signal (FE signal) by an external control device. It is a circuit for. The photodetector element 3 is formed in front of the signal processing circuit 26.

At the rear position of the semiconductor laser 2 on the upper surface of the submount 24, the monitor light receiving element 2 for feedback controlling the laser light output of the semiconductor laser 2 is provided.
5 is formed. Rear emission end face 2 of semiconductor laser 2
A part of the rear laser beam Lb emitted from b directly enters the monitor light receiving element 25.

Here, in the light source unit 10, the optical distance between the semiconductor laser 2 and the separating diffraction element 14 is equal to the optical distance from the separating diffraction element 14 through the reflecting mirror 15 to the photodetecting element 3. Is set to. Therefore, in this example, the accuracy of the relative position between the semiconductor laser 2 and the photodetector 3 is increased as follows.

As shown in FIG. 6, the substrate surface 111 of the semiconductor substrate 11 is provided with a plurality of triangular positioning marks 50 indicating the mounting positions of the semiconductor laser 2. Each mark 50 is formed outside the electrode portion 111a.
In this example, two marks 50a and 50b indicating the position of the semiconductor laser 2 in the optical axis direction and two marks 50c and 50d indicating the position in the direction orthogonal to the optical axis direction are formed.

Therefore, these marks 50 (50a to 5a)
If the semiconductor laser 2 is mounted on the submount with 0d) as a mark, the relative position between the semiconductor laser 2 and the photodetector 3 can be accurately defined. That is, when the semiconductor laser 2 is mounted on the submount 24, the marks 50 facing each other are provided.
The semiconductor laser 2 is mounted on the submount 24 so that the emission point of the semiconductor laser 2 coincides with the intersection of two line segments connecting the two. In this way, the semiconductor laser 2 and the photodetector element 3 can be positioned relative to each other. Therefore, the semiconductor laser 2 can be arranged at an accurate optical position with respect to the photodetector element 3.

Here, in this example, marks 51, which will be described later,
Each mark 50, including 52, is formed of a film-like resin. Further, in forming these marks 50, 51, 52, they are formed at the same time in the exposure process when the photodetector 3 is formed on the substrate surface 111 of the semiconductor substrate 11. That is, the exposure apparatus used for incorporating the optical detection element is used as it is. Therefore, the pattern member for forming the photodetecting element 3 and the pattern member for forming the marks 50, 51, 52 can be accurately formed on the semiconductor substrate 11 at desired positions. Therefore, the accuracy of the mark forming position can be improved.

(Structure of the light receiving element) FIG.
Are shown enlarged. As shown in this figure, the photodetector 3 is provided with seven light-receiving surfaces A, B1, B2, C, D1, D2, and E that are elongated in the width direction (X direction). The light receiving surface A is for detecting a pit signal (RF signal),
The remaining light receiving surface is for detecting a tracking error signal (TE signal) and a focus error signal (FE signal). In the photo-detecting element 3, with the light receiving surface A as the center, the remaining three light receiving surfaces are arranged in the front-rear direction in groups of three. A light receiving surface B1, a light receiving surface C, and a light receiving surface B2 are arranged in this order in front of the light receiving surface A, and a light receiving surface D1, a light receiving surface E, and a light receiving surface D2 are arranged in this order behind the light receiving surface A. There is.

The light receiving surface A of the diffracted light of the return light of the signal reproducing laser light is divided into light receiving surfaces A1 and A2, which form light spots s1 and s2, respectively. Further, the diffracted light of the return light of the one tracking error detecting laser light forms light spots s3 and s4 on the light receiving surfaces B1, B2 and C.
The diffracted light of the returning light of the other tracking error detecting laser light forms light spots s5 and s6 on the light receiving surfaces D1, D2 and E.

In this example, the RF signal is generated based on the amount of light received on the light receiving surfaces A1 and A2. Further, a detection signal of the amount of movement of the objective lens 12 is also generated by obtaining the difference S5 between the amount of light received on the light receiving surface A1 and the amount of light received on the light receiving surface A2. Further, the TE signal is generated by obtaining the difference between the sum S1 of the light receiving amounts of the light receiving surfaces B1, B2, C and the sum S2 of the light receiving amounts of the light receiving surfaces D1, D2, E. Furthermore, the light receiving surface B
The total sum S3 of the light receiving amounts of 1, B2 and E and the light receiving surfaces D1 and D2,
By calculating the difference from the sum S4 of the received light amount of C, FE
A signal is generated. These signals are generated by a control device (not shown) electrically connected to the external connection terminal 232 of the lead frame 23 of the light source unit 10.

(Mounting Structure of Reflecting Mirror and Position Adjusting Method) A mirror mounting portion 221 is integrally formed on a package cover plate 22 which is a constituent member of the package 20. The mirror attachment portion 221 is a protrusion having a trapezoidal cross section, which is formed substantially directly above the photodetecting element 3 toward the rear.
The front surface of the trapezoidal mirror mounting portion 221 is a mirror mounting surface 222 that is inclined forward by 45 degrees. The reflection mirror 15 is fixed to the mirror mounting surface 222 with an adhesive or the like.

The six return lights Lr from the optical disk 4 which enter the package 20 through the beam generation diffraction element 13 and the separation diffraction element 14 hit the reflection mirror 15 and are vertically fallen by the reflection mirror 15. To irradiate each light receiving surface of the photodetector 3.

Therefore, the reflection mirror 15 and the photodetector 3
If the relative position of is not appropriate, the return light Lr cannot be condensed on a desired light receiving surface. Therefore, in this example, the package cover plate 22 is configured to be slidable with respect to the package body 21. That is, the package body 21 has a guide surface 2 for allowing the package cover plate 22 to slide in the optical axis direction of the semiconductor laser chip 2.
1a is formed. The package cover plate 22 slides in the optical axis direction with respect to the package body 21 while a part of the lower surface thereof is guided by the guide surface 21a. This lid plate 2
With the movement of 2, the position of the reflection mirror 15 attached here also moves in the optical axis direction.

Here, as shown in FIG.
Marks 51 (51a, 51b) for designating a positional relationship with the laser light source 2 are formed in the vicinity of the photo-detecting element 3 on the substrate surface 111 of the semiconductor substrate 11 in which is formed. The triangular mark 51 is formed at both ends of the photodetector element 3 so as to be orthogonal to the optical axis direction Lu in the package 20. Using these marks 51 as a mark, the relative position between the reflection mirror 15 and the photodetector 3 is adjusted.

Next, the adjusting operation of the relative position between the photo-detecting element 3 and the reflecting mirror 15 will be described with reference to FIG. Figure 8
Inside the package of the light source unit 20, the light passage hole 2
It is the figure seen from the outside through 03. Thus, in this example, the reflection mirror 1 is externally supplied through the light passage hole 203.
It is possible to face 5.

First, the inside of the package is viewed from the light passage hole 203, and the photodetector 3A reflected on the reflection mirror 15 is observed. Further, the semiconductor laser 2 is turned on. In this way, the mark 51A formed in the vicinity of the light detecting element 3 reflected on the reflection mirror 15 and the light emitting point 2 of the semiconductor laser chip 2
The package cover plate 22 is slid with respect to the package body 21 so that A has the same height. By doing so, the position of the reflection mirror 15 is adjusted in the optical axis direction, and the relative position between the photodetector 3 and the reflection mirror 15 is automatically defined in a desired relationship. As a result, the return light Lr from the optical disc 4 can be guided to an appropriate position of the photodetector element 3. In this state, the package cover plate 22 and the package body 21 are fixed to each other via a fixing means such as an adhesive.

(Mounting Structure and Adjustment Direction of Diffraction Element for 3-Beam Generation) FIG. 9 shows the diffraction element 13 for 3-beam generation.
10 schematically shows the mounting structure, and FIG. 10 schematically shows the mounting structure of the separating diffraction element 14. As shown in FIGS. 4 and 9, in the guide surface 21 a of the frame main body 21, the reference surface 3 is provided at the boundary with the protruding portion 216.
A step surface 31 that is one step lower than 0 is formed. This step surface 31 is formed along the width direction, and the length dimension in the front-back direction is constant. The step surface 31 and the reference surface 30
A step surface 32 that is orthogonal to the step surface 31 is formed at the boundary between the step surface 31 and the step surface 31 (an attachment surface) that is orthogonal to the step surface 31 at the boundary between the step surface 31 and the extended portion 216.

Therefore, when the three-beam generating diffraction element 13 is arranged in contact with the step surface 33, the arrangement position in the front-rear direction is defined. In addition, the three-beam generating diffraction element 1
The attitude of the three-beam generation diffractive element 13 is defined so that the optical axis of 3 is substantially parallel to the optical axis Lu of the front laser beam Lf.

FIG. 11A shows a diffraction element 1 for generating three beams.
It is a top view of FIG. (B) is a diffraction element 1 for generating three beams
3 is a detailed pattern diagram of FIG. As shown in FIG. 11A, an effective area 80 and a pattern area 82 of the diffractive element 14 located inside the effective area 80 are provided on the surface of the diffractive element 13. Four marks 52, which serve as marks for positioning the diffractive element, are provided on the outer surface of the effective area 80. These marks 52 (52a to 52d) are provided with a total of four marks 52 so as to face each other in two directions of a height direction and a width direction (a plane perpendicular to the optical axis) of the package 20. Diffraction element 13 for three-beam generation
With the marks 52 as marks, the pattern is positioned at an angle of about 1.5 degrees around the intersection defined by the four marks. This direction is the 3-beam generation direction.

The mounting position of the diffraction element 13 for generating the three beams is adjusted as follows. First, the semiconductor laser 2
Turn on. This makes it easier to understand the emission point of the semiconductor laser 2. Then, the light source unit 10 is observed from the front. Next, the light emitting point of the semiconductor laser 2 and the mark 52 provided on the three-beam generating diffraction element 13 are used as marks for positioning. At this time, as shown in FIG. 9, the diffraction element 13 for three-beam generation is arranged so that the intersection C of the two line segments connecting the facing marks 52 and the emission point of the semiconductor laser 2 coincide with each other. Finely move along the step surface 33. As a result, the three-beam generating diffraction element 13 is finely adjusted to a desired position.

(Method for adjusting the position of the separating diffraction element) Next,
A method of adjusting the position of the separating diffraction element 14 will be described. As described with reference to FIG. 1, in the separating diffraction element 14, the diffraction grating surface of the separating diffraction element 14 is formed of two diffraction gratings having different diffraction characteristics with the optical axis Lu as the center. Therefore, the three light beams (return light beams) Lf reflected by the optical disc 4 are bent into optical paths toward the photodetection element 3 and, at the same time, are split into two light beams, each of which reaches the photodetection element 3. To do.

The two diffraction gratings in the separating diffraction element 14 are divided in the direction orthogonal to the track at the boundary line along the track of the optical disk 4. Therefore, when the objective lens 12 deviates from the optical axis, the intensities of the diffracted light fluxes of the two diffraction gratings change depending on the degree. If it is designed so that both intensities are the same when they match the optical axis, the amount of deviation of the objective lens 12 from the optical axis can be detected based on the amount of difference in these intensities. The position of the objective lens 12 can be feedback-controlled so that is zero. By performing such feedback control, vibration of the object lens in the track direction can be efficiently suppressed.

As a premise of such control, the objective lens 12
So that the intensity (received light amount) of the split return light becomes the same when is at the position (reference position) that coincides with the optical axis,
It is necessary to set the relative positions of the semiconductor laser 2 and the three-beam generating diffraction element 13.

In this position adjusting method, while the objective lens 12 is positioned at the reference position, the detection signal indicating that the intensity of the split light of the return light is the same can be obtained while monitoring the detection signal of the movement amount. Thus, the separation diffraction element 14 is slightly moved in the direction orthogonal to the boundary line. That is,
The mounting position of the separating diffraction element 14 is adjusted so that the respective lights split by the separating diffraction element 14 cancel each other out.

As described above, the three-beam generating diffraction element 1
3. The diffraction direction in the separating diffraction element 14 can be accurately positioned. Therefore, in the light source unit 10, the optical axis Lu of the forward laser light Lf and the three-beam generating diffraction element 13 are generated.
Since the diffraction characteristic (diffraction direction) can be set appropriately, an optically excellent optical pickup device can be realized. Further, in the optical pickup device of the present embodiment, the positioning adjustment of each optical element can be easily and accurately performed in a short time by using the marks 50 and 51. Further, in the optical pickup device of this example, the objective lens 12 is formed by using the three-beam method.
In order to accurately detect the tracking error of the above, the positioning of the diffraction element 13 can be accurately performed through the mark 52 and in a short time through the mark 52.

(Other Embodiments) In this embodiment, the positioning mark is described as a triangular mark, but the present invention is not limited to this shape, and dots, crosses, crosses, tetragons or more may be used. Of course, it may be a polygonal shape.
Further, the number of positioning marks is not limited to this.

Further, in the optical pickup device 1, the beam generating diffraction element 13 and the separation diffraction element 1 which are independent of each other are provided.
4 is used, but a single optical element having the optical characteristics of the three-beam generating diffraction element 13 on one surface and the optical characteristics of the second diffraction element on the other surface is also used. good.

The optical system of the optical pickup device 1 includes not only the optical element shown in FIG. 1, but also a lens for converting the laser light Lf into a parallel light flux, and a light flux diameter in two orthogonal directions of the laser light. A beam shaping prism for aligning, a compound prism for aligning the optical axis of the laser light emitted from another light source with the optical axis of the main light source unit 10, aperture limiting means and wavelength for reading information of optical disks of different specifications. Optical elements such as selective optical elements may also be included.

Further, in the above embodiment, the reflector is attached to the package lid side, but it is also possible to attach the reflector to the package body side and the semiconductor substrate or the like to the package lid side. is there. Therefore, in this specification, the terms "package lid" and "package body" are used as the same terms as the terms "first and second members" constituting the package.

[0070]

As described above, in the optical pickup device of the present invention, a mark indicating the relative position of the optical element is attached, and the optical element can be positioned by using such a mark as a mark. Has become. Therefore, the work of assembling the optical element in the accurately positioned state can be performed easily and accurately.

[0071]

That is, according to the present invention, the laser light source and the semiconductor substrate on which the photo-detecting element for detecting the return light emitted from the laser light source and reflected by the optical recording medium are formed are incorporated in a common package. In the optical pickup device having the light source unit having the above configuration, a positioning mark is provided near the detection element, and this mark is projected from the outside of the package through the light passage hole to the reflector attached to the package lid . The reflector is positioned by sliding the package lid in the optical axis direction with respect to the package body, using the positioning mark as a mark. Therefore, the position of the optical elements attached to both members can be adjusted with the package lid attached to the package body, and the adjustment work can be performed while observing from outside the package.
It Therefore, the positioning of the optical element mounted in the package can be performed easily and accurately.

[0073]

[0074]

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an optical system of an optical pickup device to which the present invention is applied.

2A is a schematic configuration diagram of a light source unit, FIG. 2B is a cross-sectional view taken along line BB of FIG. 2A, and FIG. 2C is C of FIG.
It is sectional drawing in the -C line.

FIG. 3 is a front view of the light source unit shown in FIG.

FIG. 4A is a plan view of a package body that is a component of a light source unit package, and FIG.
-4B line sectional view, (C) is (A) 4C-4C
It is sectional drawing in a line.

FIG. 5 is an enlarged perspective view showing a semiconductor substrate and its peripheral portion in a light source unit of the optical pickup device.

FIG. 6 is an enlarged plan view showing a substrate surface of a semiconductor substrate in a light source unit of an optical pickup device.

FIG. 7 is a plan view showing an enlarged light receiving element in the light source unit of the optical pickup device.

8 is an enlarged view schematically showing how a light receiving element is imaged on a reflection mirror in the light source unit shown in FIG.

FIG. 9: 3 in the light source unit of the optical pickup device
It is a figure for demonstrating the attachment structure of the diffraction element for beam formation.

FIG. 10 is a diagram for explaining a mounting structure of a separating diffraction element in a light source unit of an optical pickup device.

FIG. 11A is a plan view showing a mounting position of a three-beam generating diffraction element in a light source unit of an optical pickup device, and FIG. 11B is a detailed pattern diagram of the three-beam generating diffraction element.

[Explanation of symbols]

1 Optical pickup device 2 Semiconductor laser 3 Photodetector 4 optical disks 10 Light source unit 12 Objective lens 13 3 Beam Generation Diffraction Element 14 Diffraction element for separation 15 reflective mirror 19 Objective lens drive 20 packages 21 Package body 22 Package lid plate 24 submount 25 Photodetector for monitor 30 reference plane 33 Step surface 50, 51, 52 marks 80 Effective area of 3 beam generation diffractive element 81 Pattern area of three-beam generating diffraction element 90 Heat dissipation opening

Continuation of front page (56) Reference JP-A-7-134829 (JP, A) JP-A-9-288841 (JP, A) JP-A-5-166695 (JP, A) JP-A-5-73953 (JP , A) JP-A-5-181026 (JP, A) JP-A-6-309689 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G11B 7/125 G11B 7/08 G11B 7/135

Claims (2)

(57) [Claims] 1. A common package for a laser light source and a semiconductor substrate on which a photo-detecting element for detecting return light emitted from the laser light source and reflected by an optical recording medium is formed.
Optical pick-up having a light source unit built in
In the packaging device, the package contains laser light from the laser light source.
And a light passage hole for the return light is formed, and the return light is transmitted to the photodetector in the package.
A reflector that reflects the return light is arranged to guide the light.
The position of the reflector is from the outside of the package to
It is set at a position where it can be seen through the light passage hole.
The laser light source directly or directly onto the substrate surface of the semiconductor substrate.
Is mounted indirectly via a predetermined member, and the package is a package on which the semiconductor substrate is mounted.
Package and the laser light
It is assembled so that it can slide along the optical axis of
A package lid to which the reflector is attached
However, the package lid should be
The laser light source is fixed to the package body, and on the substrate surface near the photodetector.
A positioning mark indicating the relative position of the
The positioning mark is used for the positioning of the position on the reflector.
The markings are placed at a position where they can be observed through the light passage hole.
Made is to have the optical pickup device. 2. The optical pickup device according to claim 1.
In the method for adjusting the position of an optical element in an optical device , the laser light source is passed through the light passage hole of the light source unit
View the light emitting point and the positioning mark on the reflector.
While sliding the package lid
Position the more the reflector, after adjusting the position of the reflector, the package lid
An optical pick, which is fixed to the package body.
A method for adjusting the position of an optical element in a backup device.