JP2010098148A - Frame type laser diode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a frame type laser diode suitable for thinning an optical pickup device. <P>SOLUTION: The frame type laser diode is used as a laser light source of an optical pickup device for reading out a signal recorded on an optical disk and has a laser diode chip mounted to a plane where a metallic lead frame is provided, and the laser diode chip 19 is disposed so that a PN junction surface of the laser diode chip 19 is perpendicular to the plane of the lead frame 17. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a frame type laser diode used as a laser light source of an optical pickup device that performs a read operation of a signal recorded on an optical disc and a recording operation of a signal on an optical disc.

  2. Description of the Related Art Optical disk apparatuses that can perform signal reading operation and signal recording operation by irradiating a signal recording layer of an optical disk with laser light emitted from an optical pickup device have become widespread.

  As an optical disk apparatus, an apparatus using an optical disk called a CD or a DVD is widely used. As a laser beam for performing an operation for reading a signal recorded on a CD standard optical disk, an infrared light having a wavelength of 780 nm is used, and a laser beam for performing an operation for reading a signal recorded on a DVD standard optical disk. In this case, red light having a wavelength of 650 nm is used.

  The protective layer provided on the upper surface of the signal recording layer in the CD-standard optical disc has a thickness of 1.2 mm, and an aperture of an objective lens used for performing a signal reading operation from the signal recording layer. The number is defined as 0.45. Further, the thickness of the protective layer provided on the upper surface of the signal recording layer in the DVD standard optical disc is 0.6 mm, and the numerical aperture of the objective lens used for performing the signal reading operation from the signal recording layer Is defined as 0.6.

The configuration of an optical pickup device that performs a read operation of a signal recorded on a DVD standard optical disc will be described with reference to the schematic diagram shown in FIG.
In FIG. 5, reference numeral 1 denotes a DVD standard optical disk, that is, a laser diode that emits laser light focused on an optical disk D provided with a signal recording layer L at a position indicated by a broken line in the figure, and has a red wavelength band of 645 nm. It is configured to generate laser light having a wavelength of ˜675 nm, for example, 650 nm.

  A diffraction grating 2 is provided at a position where the laser light emitted from the laser diode 1 is incident, and has a function of separating and generating a main beam that is zero-order diffracted light and a sub beam that is ± first-order diffracted light. Is. Reference numeral 3 denotes a half-wave plate on which the laser beam transmitted through the diffraction grating 2 is incident, and functions to adjust the polarization direction.

  Reference numeral 4 denotes a polarization beam splitter on which the laser light transmitted through the half-wave plate 3 is incident. The control film 4a reflects a part of the P-polarized light and transmits most of the P-polarized light and reflects the S-polarized light. Is provided. Laser light emitted from the laser diode 1 is converted into P-polarized light by the half-wave plate 2 and is incident on the polarization beam splitter 4.

Reference numeral 5 denotes a front monitor diode provided at a position where the laser beam reflected by the control film 4 a provided in the polarizing beam splitter 4 is irradiated, and corresponds to the intensity of the laser beam emitted from the laser diode 1. The monitor signal is output. Therefore, the intensity of the laser light emitted from the laser diode 1 is set to a desired level by adjusting the level of the drive signal supplied to the laser diode 1 using the monitor signal obtained from the front monitor diode 5. Can be controlled automatically.

  Reference numeral 6 denotes a collimating lens provided at a position where the laser beam transmitted through the polarizing beam splitter 4 is incident, and has an action of converting the incident laser beam into parallel light. Reference numeral 7 denotes a reflection mirror on which the laser light converted into parallel light by the collimating lens 6 is incident, and has an action of changing the optical axis in a perpendicular direction.

  A quarter wave plate 8 is provided at a position where the laser beam reflected by the reflection mirror 7 is incident. The laser beam is converted from linearly polarized light to circularly polarized light, and vice versa. It acts to polarize linearly polarized light. Reference numeral 9 denotes an objective lens that is provided at a position where the laser beam transmitted through the quarter-wave plate 8 is irradiated and has a numerical aperture of 0.6. The light condensing is performed on the signal recording layer L.

  The laser light condensed by the objective lens 9 on the signal recording layer L provided on the optical disc D is reflected by each signal recording layer L and is incident on the objective lens 9 as return light from the optical disc D side. The return light incident on the objective lens 9 passes through the objective lens 9 and then enters the quarter-wave plate 8.

  The return light incident on the ¼ wavelength plate 8 is converted from circularly polarized light to linearly polarized light by the ¼ wavelength plate 8, but is applied to the ¼ wavelength plate 8 to irradiate the optical disc D. Since the incident laser light is P-polarized light, the return light is S-polarized light. The return light converted into S-polarized light by the quarter-wave plate 8 is reflected by the reflecting mirror 7 and then enters the collimating lens 6.

  The return light incident on the collimating lens 6 passes through the collimating lens 6 and enters the polarizing beam splitter 4. Since the return light incident on the polarizing beam splitter 4 is converted into S-polarized light by the quarter-wave plate 8 as described above, it passes through the control film 4a provided on the polarizing beam splitter 4. All can be reflected without.

  Reference numeral 10 denotes a sensor lens provided at a position where the return light reflected by the control film 4a provided in the polarizing beam splitter 4 is incident, and generates astigmatism for generating a focus error signal. In addition, the light receiving unit provided in the photodetector 11 is irradiated with the return light. Such a light detector 11 incorporates a light receiving unit called a four-divided sensor, and a focus error signal and a tracking error signal are generated based on a signal obtained from such a light receiving unit. Since it is well known, its description is omitted.

  In the optical pickup device having the optical configuration shown in the schematic diagram of FIG. 5, the signal recorded on the signal recording layer L of the optical disc D is read by performing a focus control operation, a tracking control operation, a demodulation operation of the read signal, and the like. An operation and a signal recording operation on the signal recording layer L can be performed. Next, the shape of a spot generated by irradiating the signal recording layer L with laser light will be described.

  The laser diode 1 incorporates a laser diode chip that emits laser light, and the laser diode chip is provided with an active layer called a PN junction surface as is well known. And the laser beam radiated | emitted from such a PN junction surface has the characteristic that the diameter of a direction perpendicular | vertical to an active layer is longer than the diameter of a direction horizontal to an active layer.

  Since such elliptical laser light is emitted from the laser diode 1, the laser spot formed on the signal recording layer L of the optical disc D by the focusing operation of the objective lens 9 becomes elliptical.

  The reading operation of the signal recorded on the signal recording layer L is performed by such an elliptical laser spot, but the elliptical major axis direction and the direction of the signal track need to be in an optimum relationship. In order to read out signals recorded on an optical disc of the standard called DVD + R, it is advantageous to arrange the laser spot so that the major axis direction of the laser spot is perpendicular to the signal track. There is a problem that it becomes difficult to read an LPP signal (address signal) provided on an optical disc of the DVD-R standard.

  In order to solve such a problem, the major axis direction of the laser spot is inclined by 60 degrees with respect to the signal track as shown in FIG. Laser diodes include a can type formed of a cylindrical package and a frame type formed of a flat package. An optical disc device incorporated in a notebook personal computer is required to be thin, and an optical pickup device incorporated in such an optical disc device is also required to be thin.

  Since the frame type laser diode is suitable for being thinner than the can type, the laser diode incorporated in the thin optical pickup device is generally a frame type.

  FIG. 7 is a side view showing an optical pickup device in which a frame type laser diode is incorporated. In FIG. 7, reference numeral 12 denotes a base constituting the optical pickup device. A lower surface 12B provided in parallel with the upper surface 12A is provided.

  In such a configuration, each optical component described in FIG. 5 is disposed between the upper surface 12A and the lower surface 12B. In the optical pickup device, the distance between the upper surface 12A and the lower surface 12B, that is, the thickness. Is required to be thin.

  Reference numeral 13 denotes a metal lead frame constituting a frame type laser, and is provided with a flat plate portion 13A. Reference numeral 14 denotes a submount fixed to the flat plate portion 13A of the lead frame 13. A laser diode chip 15 is fixed on the submount 14 and is electrically connected to one pole of the laser diode chip 15. Has been.

  Reference numeral 16 denotes a resin frame for fixing the lead frame 13 and a terminal frame provided to supply a driving signal to the laser diode by molding a synthetic resin material. Such a terminal frame is a terminal connected to the laser drive circuit, and is provided in at least one pair, and is electrically connected to the terminal frame, one pole of the laser diode chip 15 and the submount 14 by wires. ing.

  In such a configuration, the PN junction surface 15A of the laser diode chip 15 is configured to be parallel to the flat plate portion 13A of the lead frame 13 as illustrated. In such a configuration, in order to incline the laser spot generated by being focused on the signal recording layer L of the optical disc D by 60 degrees with respect to the signal track as shown in FIG. It is necessary to arrange optical components for tilting the laser spot with respect to the optical system provided to guide the light to the objective lens 9.

If an optical component for tilting the laser spot with respect to the signal track is provided in the optical system, the frame type laser diode can be used without changing the thickness of the base 12 constituting the optical pickup device. Since the configuration becomes complicated and the number of parts increases, there is a problem that the price increases.

  As a simple method for solving such a problem, there is a method of rotating and arranging a frame type laser diode as shown in FIG. That is, when the laser diode is inclined as shown in the drawing, the PN junction surface 15A of the laser diode chip 15 is rotated around the optical axis of the laser beam, so the angle of the laser spot in the major axis direction is set with respect to the signal track. It can be changed and set as shown in FIG.

Although the tilt angle of the laser spot with respect to the signal track can be changed and set to an optimum state by rotating the frame type laser diode, the thickness of the base 12 constituting the optical pickup device as shown in FIG. There is a problem that the amount of As a method for solving such a problem, a technique for changing the angle of the laser diode chip 15 fixed to the lead frame 13 has been proposed. (See Patent Document 1.)
JP 2006-269857 A

  9 (a), 9 (b), and 9 (c) show the shape of the lead frame described in the above-mentioned patent document. If a lead frame having such a shape is used, light using a frame type laser diode is shown. Although it is possible to reduce the thickness of the pickup device, the chip mounting part having an inclined surface is formed on the lead frame itself, so that not only the manufacture is simple, but also light that requires various inclination angles of the laser spot. In order to correspond to the pickup device, it is necessary to manufacture a lead frame in which mounting portions of various inclination angles are formed corresponding to each optical pickup device, so that the increase in price cannot be suppressed. There is.

  Further, the pole of the laser diode chip fixed on the lead frame and the terminal frame are electrically connected by a wire, and such a connecting operation is performed by a welding technique called wire bonding.

  As a wire bonding method for electrically connecting the laser diode chip and the terminal frame with wires, a method called ultrasonic bonding using ultrasonic waves is generally used in many cases. Such ultrasonic bonding is performed by increasing the temperature by vibrating the bonding portion by ultrasonic vibration and welding the terminal and the wire.

  Such ultrasonic bonding is efficient if the wire is brought into perpendicular contact with a terminal which is a bonding portion of the wire, that is, a terminal provided on the laser diode chip, and no ultrasonic wave is applied to the terminal from the vertical direction. It has the characteristic that it cannot be welded well.

  The lead frame described in the patent document has a problem that the ultrasonic bonding operation described above cannot be performed efficiently because the mounting portion to which the laser diode chip is fixed is inclined as shown in FIG. is there.

  The present invention is intended to provide a frame type laser diode that can solve the above-described problems and is suitable for thinning an optical pickup device.

  The present invention is a frame-type laser diode that is used as a laser light source of an optical pickup device that reads a signal recorded on an optical disc, and in which a laser diode chip is mounted on a plane provided on a metal lead frame. The PN junction surface of the laser diode chip is arranged so as to be perpendicular to the plane of the lead frame.

  In the frame type laser diode of the present invention, since the PN junction surface of the laser diode chip is arranged to be perpendicular to the plane of the lead frame, the rotation angle with respect to the base constituting the optical pickup device can be reduced. As a result, the optical pickup device is greatly reduced in thickness.

  In the frame type laser diode of the present invention, after fixing the laser diode chip to the submount, the laser diode chip and the printed wiring pattern are connected by wire bonding, and the submount is fixed to the lead frame. Therefore, there is an advantage that the welding operation using ultrasonic vibration can be performed efficiently and the connection operation can be performed reliably.

  1 is a side view showing a frame type laser diode according to the present invention, FIG. 2 is a plan view showing the frame type laser diode according to the present invention, and FIG. 3 shows an optical pickup device incorporating the frame type laser diode according to the present invention. FIG. 4 is a perspective view of the main part for explaining the method for manufacturing the frame type laser diode of the present invention.

  In FIG. 1, reference numeral 17 denotes a metal lead frame constituting a frame type laser diode, and is provided with a flat plate portion 17A which is a main plane. Reference numeral 18 denotes a submount in which the laser diode chip 19 is fixed to the side surface 18A as shown in the figure, and is bonded and fixed to a mounting portion provided on the flat plate portion 17A of the lead frame 17.

  The frame type laser diode of the present invention is configured as shown in FIG. 1. As is clear from FIG. 1, the PN junction surface 19A of the laser diode chip 19 is a plane which is the flat plate portion 17A of the lead frame 17. It is comprised so that it may become perpendicular | vertical to.

  FIG. 3 is a side view showing a state in which the frame type laser diode having such a configuration is incorporated in the base 20 of the optical pickup device so that the angle of the major axis direction of the laser spot with respect to the signal track becomes the angle shown in FIG. As is apparent from the figure, the frame type laser diode of the present invention is arranged so that the PN junction surface 19A of the laser diode chip 19 is perpendicular to the plane of the lead frame 17, so that the base of the frame type laser diode is provided. The rotation angle with respect to 20 can be made smaller than that of the conventional frame type laser diode shown in FIG.

  Therefore, when the frame type laser diode of the present invention is incorporated in the base 20 of the optical pickup device, the thickness of the base 20 can be reduced as compared with the case where the conventional frame type laser diode is used. .

  As described above, the frame type laser diode of the present invention is configured. Next, assembly will be described.

FIG. 4 is a perspective view for explaining the structure of the submount 18 constituting the frame type laser diode of the present invention. In the figure, 21 is a printed wiring pattern wired from the side surface 18A to the top surface 18B of the submount 18, and 22 is an insulating pattern for electrically blocking the printed wiring pattern 21 and the conductive surface 18C of the submount 18. It is.

  In such a configuration, one electrode of the laser diode chip 19 is bonded and fixed to the conductive surface 18C of the submount 18 with a conductive adhesive such as silver paste, and the other electrode is electrically connected to the printed wiring pattern 21 by the wire 23. Connected. The connection of the wire 23 to the electrode of the laser diode chip 19 and the connection with the printed wiring pattern 21 are performed by ultrasonic bonding. Since such an ultrasonic bonding operation can be performed from the direction perpendicular to the side surface 18A of the submount 18, the connection operation of the wire 23 to the electrode of the laser diode chip 19 and the connection operation with the printed wiring pattern 21 are efficient. Good and reliable.

  As described above, the fixing operation of the laser diode chip 19 to the submount 18 is performed. The submount 18 assembled in this way is bonded and fixed to the mounting portion of the flat plate portion 17A provided on the lead frame 17. Thus, the submount 18 can be fixed at a predetermined position.

  In the plan view shown in FIG. 2, reference numeral 24 denotes a resin frame for fixing and holding the lead frame 17 and terminal frames 25 and 26 provided to supply drive signals to the laser diode chip 19, and molding a synthetic resin material. It is comprised so that it may be manufactured by. Such terminal frames 25 and 26 are terminals electrically connected to the laser drive circuit, and at least one pair is provided. The terminal frames 25 and 26 are connected to the printed wiring pattern 21 printed and wired to the submount 18 and the conductive surface 18C of the submount 18 by wires 27 and 28, respectively.

  The connection operation of the wire 27 that connects the printed wiring pattern 21 printed on the submount 18 and the terminal frame 25 and the connection operation of the wire 28 that connects the conductive surface 18C of the submount 18 and the terminal frame 26 are as follows. The ultrasonic bonding operation described above is performed. Such an ultrasonic bonding operation can be performed from the vertical direction with respect to the upper surface of the submount 18 and the vertical direction with respect to the terminal frames 25, 26. Therefore, the connection operation with each part of the wires 27 and 28 can be performed efficiently. And it can be done reliably.

  Further, in the lead frame 17 according to the present invention, through holes 29 and 30 for fixing the optical pickup device to the base 20 are provided in a portion protruding from the resin frame 24 to the outside. Accordingly, the laser diode can be fixed by a screw or the like using the through holes 29 and 30. The heat generated from the laser diode chip 19 can be released by the transmission action to the base 20 by the lead frame 17 and the lead frame 17.

  In this embodiment, the laser diode used in the optical pickup device that performs the reading operation of the signal recorded on the DVD standard optical disc has been described. However, the operation of reading the signal recorded on the CD standard optical disc has been described. Of course, it can be employed in a laser diode used in an optical pickup device. Furthermore, it is also possible to employ a frame type laser diode in which a two-wavelength laser diode that emits two-wavelength laser light corresponding to each DVD standard and CD standard optical disc is incorporated.

  In the present embodiment, the lead frame 18 is provided with the through holes 26 and 27 for fixing the optical pickup device to the base 17, but a notch or the like may be provided as a means for fixing. I can do it.

It is a side view showing a frame type laser diode of the present invention. It is a top view which shows the flame | frame type laser diode of this invention. It is a side view which shows the optical pick-up apparatus incorporating the flame | frame type laser diode which concerns on this invention. It is a perspective view of the principal part for demonstrating the manufacturing method of the flame type laser diode of this invention. It is the schematic for demonstrating the optical system of the optical pick-up apparatus which concerns on this invention. It is a figure for demonstrating the relationship between a signal track | truck and a laser spot. It is a side view which shows the optical pick-up apparatus incorporating the conventional flame | frame type laser diode. It is a side view which shows the optical pick-up apparatus incorporating the conventional flame | frame type laser diode. It is a side view which shows the shape of the conventional lead frame.

Explanation of symbols

17 Lead frame 17A Flat plate portion 18 Submount 19 Laser diode chip 21 Printed wiring pattern 22 Insulating pattern 24 Resin frame

Claims (4)

A frame type laser diode that is used as a laser light source of an optical pickup device that reads a signal recorded on an optical disc and that has a laser diode chip mounted on a flat surface provided on a metal lead frame. A frame type laser diode, characterized in that the PN junction surface is perpendicular to the plane of the lead frame. A printed wiring pattern is formed on which a laser diode chip is mounted and electrically connected to one pole of the laser diode chip and electrically connected to the other pole on a submount fixed to the lead frame. The frame type laser diode according to claim 1, wherein: The laser diode chip and the printed wiring pattern are connected by wire bonding after fixing the laser diode chip to the submount, and the submount is fixed to the lead frame. Frame type laser diode. The resin frame is formed by molding the lead frame with resin, and the lead frame, the printed wiring pattern, and the terminal frame connected by wire bonding are fixed by the resin frame. 3. A frame type laser diode according to item 3.

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