JP2015041399A - Transmission line structure, optical pickup and optical disc device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission line structure, an optical pickup and an optical disc device that attain high efficiency of a transmission, and enable a desired input to be taken out even when using a single layer type flexible wiring board.SOLUTION: A transmission line structure 30 provided in an optical pickup 10 of an optical disc device 1 comprises: a single layer type flexible wiring board 31 that includes an insulator part 31a and a transmission line 31b provided inside the insulator part 31a; and a ground conductor part 33 that is tightly brought into contact with one outer surface of the flexible wiring board 31, and is composed of a conductor part of the optical disc device 1.

Description

  The present invention relates to a transmission line structure, an optical pickup, and an optical disc apparatus.

  An optical disc device is used when reading information from an optical disc such as a BD (Blu-ray (registered trademark) Disc), a DVD (Digital Versatile Disc), or a CD (Compact Disc) or writing information on an optical disc. The optical disk apparatus irradiates light from a light source toward the optical disk using an optical pickup, reads the light reflected by the optical disk, converts it into an electrical signal, and outputs it. Such a conventional optical disc apparatus is disclosed in, for example, Japanese Patent Application Laid-Open No. H10-228707.

  The conventional optical disk device described in Patent Document 1 includes an objective lens that focuses light to irradiate an optical disk with an optical disk, an objective lens actuator that adjusts the position of the objective lens, an objective lens, and an objective lens actuator And a carriage movable in the radial direction of the optical disc. A flexible cable is used for power supply and signal transmission to the carriage. The flexible cable is said to be effective in that it has good flexibility and does not hinder the movement of the carriage and reduces the cable installation space.

JP-A-6-150580

  Here, for example, in the transmission path from the light source driving circuit to the light source, it is necessary to perform impedance matching of the transmission path in order to ensure recording characteristics such as rising of light emission and overshoot more than desired. For this reason, it has been necessary to use a two-layer flexible wiring board in which one conductor such as a micro split line is a transmission line and the other conductor is a ground conductor. However, since the two-layer flexible wiring board is relatively expensive, there has been a concern that the cost of the device will increase. The use of a relatively inexpensive single-layer flexible wiring board has been desired.

  The present invention has been made in view of the above points, and even when a single-layer type flexible wiring board is used, transmission capable of improving transmission efficiency and taking out a desired input is possible. An object of the present invention is to provide a line structure, an optical pickup, and an optical disk device.

  In order to solve the above problems, a transmission line structure according to the present invention is a transmission line structure provided in a device, and includes a single-layer flexible wiring including an insulator part and a transmission line provided inside the insulator part. And a ground conductor composed of a conductor portion of the device in close contact with at least one outer surface of the flexible wiring board.

  According to this configuration, the ground conductor is provided on the outer surface of the single-layer flexible wiring board. Therefore, since the configuration is the same as that of the two-layer flexible wiring board, transmission efficiency can be improved.

  In the transmission line structure having the above-described configuration, a holding portion that holds the flexible wiring board while being pressed toward the ground conductor is provided.

  According to this configuration, the accuracy with which the ground conductor is in close contact with the outer surface of the single-layer flexible wiring board is increased. Therefore, since the configuration is closer to that of a two-layer flexible wiring board, transmission efficiency can be improved.

  Moreover, the transmission line structure having the above-described configuration is characterized in that an adhesive is provided for bringing the flexible wiring board into close contact with the ground conductor.

  According to this configuration, the accuracy with which the ground conductor is in close contact with the outer surface of the single-layer flexible wiring board is further increased. Therefore, since the configuration is closer to that of the two-layer flexible wiring board, transmission efficiency can be improved.

  The optical pickup according to the present invention includes the above transmission line structure.

  According to this configuration, transmission efficiency can be improved in the optical pickup.

  In the optical pickup having the above-described configuration, a light source and a drive circuit for the light source are provided, and the transmission line structure is used for electrically connecting the light source and the drive circuit. .

  According to this configuration, transmission efficiency is improved in the transmission path from the light source driving circuit to the light source. Accordingly, it is possible to secure more than desired recording characteristics such as rising of light emission and overshoot.

  The optical disc apparatus according to the present invention includes the above transmission line structure.

  According to this configuration, transmission efficiency is improved in the optical disc apparatus.

  According to the configuration of the present invention, even when a single-layer type flexible wiring board is used, a transmission line structure, an optical pickup, and an optical disc capable of taking out a desired input with improved transmission efficiency An apparatus can be provided.

1 is a configuration diagram of an optical disc apparatus according to a first embodiment of the present invention. It is sectional drawing which shows the transmission line structure between the laser element of the optical disk apparatus based on 1st Embodiment of this invention, and a laser element drive circuit. It is sectional drawing which shows the transmission line structure between the laser element of the optical disk apparatus based on 2nd Embodiment of this invention, and a laser element drive circuit. It is a top view of the flexible wiring board of the optical disc device concerning a 2nd embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. Note that the optical disk apparatus according to the present embodiment can read and write information from and to a standard optical disk such as BD, DVD, and CD.

<First Embodiment>
First, an outline of the configuration of the optical disc apparatus according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a configuration diagram of an optical disc apparatus. The optical disk is arranged on the front side of the drawing in FIG.

  The optical disc apparatus 1 includes an optical pickup 10, a signal processing unit 2, and a control unit 3 as shown in FIG. The optical pickup 10 includes a first laser element 11, a beam splitter 12, a polarization beam splitter 13, a quarter wavelength plate 14, a collimator lens 15, a first split mirror 16, a first objective lens 17, a second laser element 18, Diffraction element 19, second split mirror 20, second objective lens 21, cylindrical lens 22, photodetector 23, monitor unit 24, first laser element driving circuit (LDD1) 25 and second laser element driving circuit (LDD2) 26 Is provided.

  The optical pickup 10 has a configuration in which a plurality of optical members are shared by the optical path for DVD and CD and the optical path for BD. Thereby, the optical pickup 10 can cope with BD, DVD and CD with a small number of parts, and the configuration is further downsized.

  First, each component will be described with respect to optical paths for DVD and CD. The first laser element 11 is a semiconductor laser element. The first laser element 11 is composed of a two-wavelength laser that can switch between a laser beam having a wavelength of 650 nm for DVD and a laser beam having a wavelength of 780 nm for CD. When a drive current is supplied from the first laser element drive circuit 25 controlled by the control unit 3, the first laser element 11 emits a laser beam having an intensity corresponding to the drive current.

  The laser beam emitted from the first laser element 11 is reflected by the beam splitter 12 and passes through the polarization beam splitter 13. The polarization beam splitter 13 is an optical member that acts on the BD laser beam, and transmits the DVD and CD laser beams regardless of their polarization states.

  The laser beam of the first laser element 11 that has passed through the polarization beam splitter 13 passes through the quarter-wave plate 14, reaches the collimator lens 15, and is converted into parallel light. The collimating lens 15 can be moved in the optical axis direction (the direction of the white arrow shown in FIG. 1) by a lens driving mechanism (not shown). The collimating lens 15 is appropriately moved according to the type of optical disk, layer jump, and the like. The collimating lens 15 is movable so that the influence of spherical aberration can be appropriately suppressed by adjusting the degree of convergence and divergence of the laser light incident on the first objective lens 17 and the second objective lens 21. It is.

  The laser light composed of the parallel light of the first laser element 11 that has passed through the collimator lens 15 is reflected at a predetermined reflection angle by the first split mirror 16 and reaches the first objective lens 17. The first objective lens 17 focuses the incident laser beam on the information recording surface of the optical disc.

  The laser light of the first laser element 11 condensed on the information recording surface of the optical disk by the first objective lens 17 is reflected by the information recording surface and becomes return light. The return light of the first laser element 11 passes through the first objective lens 17 and is then reflected by the first split mirror 16, and sequentially passes through the collimator lens 15, quarter-wave plate 14, polarizing beam splitter 13, and beam splitter 12. The return light of the first laser element 11 that has passed through the beam splitter 12 passes through the cylindrical lens 22 to correct astigmatism, and is collected in a predetermined light receiving region of the photodetector 23.

  The photodetector 23 photoelectrically converts the incident return light of the first laser element 11 into an electric signal and outputs it. The electrical signal output from the photodetector 23 is sent to the signal processing unit 2. The signal processing unit 2 generates a reproduction signal, a focus error signal, a tracking error signal, and the like. The focus error signal and the tracking error signal are output to the control unit 3, and the control unit 3 uses them for focusing control and tracking control for performing proper position adjustment of the first objective lens 17. The position of the first objective lens 17 can be adjusted by a lens position adjusting mechanism (not shown).

  Next, each component will be described with respect to the optical path for BD. The second laser element 18 is a semiconductor laser element. The second laser element 18 can emit a laser beam having a wavelength of 405 nm, for example, for BD. When a drive current is supplied from the second laser element drive circuit 26 controlled by the control unit 3, the second laser element 18 emits a laser beam having an intensity corresponding to the drive current.

  The laser beam emitted from the second laser element 18 is divided into main light and two sub-lights by the diffraction element 19. The laser beam of the second laser element 18 that has passed through the diffraction element 19 is reflected by the polarization beam splitter 13.

  The laser beam of the second laser element 18 that has passed through the polarization beam splitter 13 passes through the quarter-wave plate 14, reaches the collimator lens 15, and is converted into parallel light. Laser light composed of parallel light from the first laser element 11 that has passed through the collimator lens 15 reaches the first split mirror 16. The first split mirror 16 is a dichroic mirror, which reflects DVD and CD laser light, but allows BD laser light to pass therethrough.

  The laser beam of the second laser element 18 that has passed through the first split mirror 16 is reflected by the second split mirror 20 at a predetermined reflection angle and reaches the second objective lens 21. The second objective lens 21 condenses the incident laser beam on the information recording surface of the optical disc.

  The laser beam of the second laser element 18 condensed on the information recording surface of the optical disk by the second objective lens 21 is reflected by the information recording surface and becomes return light. The return light of the second laser element 18 is reflected by the second split mirror 20 after passing through the second objective lens 21, and is reflected by the first split mirror 16, the collimating lens 15, the quarter wavelength plate 14, the polarization beam splitter 13, and the beam splitter. 12 is sequentially transmitted. The return light of the second laser element 18 that has passed through the beam splitter 12 passes through the cylindrical lens 22 to correct astigmatism, and is collected in a predetermined light receiving region of the photodetector 23.

  The photodetector 23 photoelectrically converts the incident return light of the second laser element 18 into an electric signal and outputs it. The electrical signal output from the photodetector 23 is sent to the signal processing unit 2. The signal processing unit 2 generates a reproduction signal, a focus error signal, a tracking error signal, and the like. The focus error signal and the tracking error signal are output to the control unit 3, and the control unit 3 uses them for focusing control and tracking control for adjusting the proper position of the second objective lens 21. The position of the second objective lens 21 can be adjusted by a lens position adjusting mechanism (not shown).

  The first split mirror 16 reflects a part of the laser beam of the first laser element 11 as the first objective emission light toward the first objective lens 17, and the remainder of the laser beam of the first laser element 11 is the first. Transmits as monitor light. Similarly, the second split mirror 20 reflects a part of the laser light of the second laser element 18 as the second objective outgoing light toward the second objective lens 21, and the remaining laser light of the second laser element 18 is reflected to the second objective lens 21. 2 Transmitted as monitor light. The second split mirror 20 transmits the first monitor light of the first laser element 11.

  The monitor unit 24 receives the first monitor light of the first laser element 11 and the second monitor light of the second laser element 18, photoelectrically converts them into electrical signals, and outputs them. The electrical signal output from the monitor unit 24 is sent to the control unit 3. Based on the received signals relating to the first monitor light and the second monitor light, the control unit 3 passes the first laser element drive circuit 25 and the second laser element drive circuit 26 through the first laser element 11 and the second laser element. 18 laser outputs are controlled.

  Next, a transmission line structure between the laser element of the optical disk device 1 and the laser element driving circuit will be described with reference to FIG. 2 in addition to FIG. FIG. 2 is a cross-sectional view showing a transmission line structure between the laser element of the optical disk apparatus 1 and the laser element driving circuit.

  A transmission line structure between the first laser element 11 and the first laser element driving circuit (LDD1) 25, and a transmission line structure between the second laser element 18 and the second laser element driving circuit (LDD2) 26. Have the same structure, the same reference numerals are assigned to each of them, and one of them will be described below. Moreover, each transmission line structure may share the flexible wiring board mentioned later.

  The transmission line structure 30 between the laser element and the laser element driving circuit of the optical disc apparatus 1 includes a flexible wiring board 31, a wiring board guide part 32, a ground conductor part 33, and a holding part 34 as shown in FIG. Note that the transmission line 31b of the flexible wiring board 31 extends along the depth direction in FIG. 2, and the horizontal direction in FIG. 2 is the width direction of the flexible wiring board 31.

  The flexible wiring board 31 includes an insulator 31a and a transmission line 31b, and is a highly flexible wiring board. The insulator 31a is made of, for example, a base film (not shown), an adhesive layer, a coverlay, and the like. The base film and the coverlay are made of a synthetic resin such as polyimide or polyethylene terephthalate. The insulator 31a is provided with a transmission line 31b, which is a conductor made of metal such as copper, in the inside, that is, between the base film and the coverlay. The flexible wiring board 31 is a single-layer flexible wiring board in which transmission lines 31b are arranged in a single layer in the thickness direction.

  The wiring board guide portion 32 is provided in contact with one surface of the casing 27 of the optical pickup 10. The wiring board guide portion 32 has a substantially rectangular cross section with a size capable of accommodating the flexible wiring board 31 and includes the flexible wiring board 31. The flexible wiring board 31 is accommodated in the wiring board guide portion 32 through an opening 32a provided on the upper surface of the wiring board guide portion 32 in FIG.

  The ground conductor portion 33 is provided inside the wiring board guide portion 32. The ground conductor portion 33 protrudes toward the flexible wiring board 31, that is, upward from the inner bottom surface of the wiring board guide portion 32 in FIG. 2, and extends along the direction in which the flexible wiring board 31 extends (the depth direction in FIG. 2). It consists of elongated ridges. The flexible wiring board 31 is placed on the upper surface of the ground conductor portion 33 in FIG. The ground conductor portion 33, that is, the casing 27 is a conductor and is electrically grounded (GND).

  The holding unit 34 is provided as a part of the heat sink 28 of the optical pickup 10. The holding part 34 is formed by bending a part of the heat sink 28 so as to have a shape and size that can be inserted into the opening 32a of the wiring board guide part 32 from the upper side to the lower side in FIG. The holding part 34 contacts the upper surface of the flexible wiring board 31 in FIG. The holding part 34 presses the flexible wiring board 31 toward the ground conductor 33 from the upper side in FIG. 2 to bring it into close contact, and holds the flexible wiring board 31 inside the wiring board guide part 32.

  In the transmission line structure 30, the thickness of the coverlay is adjusted in the flexible wiring board 31 in order to perform impedance matching. For this reason, the flexible wiring board 31 is disposed so that the coverlay side is in close contact with the ground conductor portion 33. Alternatively, the flexible wiring board 31 may be in close contact with the ground conductor portion 33 only in a necessary region between the laser element and the laser element driving circuit.

  As described above, the transmission line structure 30 provided in the optical pickup 10 of the optical disc apparatus 1 according to the embodiment of the present invention includes the insulator part 31a and the transmission line 31b provided inside the insulator part 31a. Flexible wiring board 31 and a grounding conductor portion 33 composed of a conductor portion of the optical disc apparatus 1 in close contact with one outer surface of the flexible wiring board 31. As a result, the ground conductor is provided on the outer surface of the single-layer flexible wiring board 31. Therefore, since the configuration is the same as that of the two-layer flexible wiring board, it is possible to increase the transmission efficiency. In other words, in the laser element, recording characteristics such as rising of laser light emission and overshoot can be ensured more than desired.

  Further, the transmission line structure 30 includes a holding portion 34 that holds the flexible wiring board 31 while pressing the flexible wiring board 31 toward the ground conductor portion 33. Thereby, the precision which the grounding conductor part 33 closely_contact | adheres to the outer surface of the single layer type flexible wiring board 31 can be improved. Therefore, since the configuration is closer to that of a two-layer flexible wiring board, it is possible to increase the efficiency of transmission.

Second Embodiment
Next, the configuration of the optical disc apparatus according to the second embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a cross-sectional view showing a transmission line structure between a laser element of the optical disk device and a laser element driving circuit, and FIG. 4 is a plan view of a flexible wiring board of the optical disk device. Since the basic configuration of this embodiment is the same as that of the first embodiment described with reference to FIGS. 1 and 2, the same reference numerals are assigned to the same components as those of the first embodiment. The description of the drawings and the description thereof will be omitted.

  In the optical disc device 1 according to the second embodiment, the transmission line structure 30 includes a flexible wiring board 31, a ground conductor part 33, a groove part 35, an adhesive 36, and a holding part 37 as shown in FIG.

  The ground conductor portion 33 includes a plurality of groove portions 35. The groove 35 extends in parallel along the direction in which the flexible wiring board 31 extends (the depth direction in FIG. 3).

  The adhesive 36 is filled in the groove 35. The adhesive 36 preferably has a high degree of cure shrinkage. By acting on the adhesive 36, the flexible wiring board 31 comes into close contact with the upper surface of the ground conductor 33 in FIG. 3.

  The holding unit 37 is provided as a part of the housing 27 of the optical pickup 10. The holding portions 37 are respectively arranged at locations corresponding to both ends of the flexible wiring board 31 in the width direction (lateral direction in FIG. 3). The holding portion 37 protrudes toward the flexible wiring board 31, that is, upward from the upper surface of the housing 27 in FIG. 3, and toward the outer side in the width direction of the flexible wiring board 31 at a position corresponding to the upper surface of the flexible wiring board 31. It is bent like a hook.

  With respect to the holding portion 37, the flexible wiring board 31 includes a protruding piece 31c and a through hole 31d as shown in FIGS. The protruding pieces 31 c protrude outward from both ends in the width direction of the main body of the flexible wiring board 31. The through hole 31d has a shape and size into which the holding portion 37 can be inserted, and penetrates in the thickness direction of the flexible wiring board 31 at each of the two protruding pieces 31c.

  When the flexible wiring board 31 is placed on the upper surface of the ground conductor portion 33 in FIG. 3, the flexible wiring board 31 is placed so as to be hooked through the through hole 31 d of the flexible wiring board 31. The holding portion 37 has a shape and a size for holding the flexible wiring board 31 by pressing the flexible wiring board 31 toward the ground conductor 33 from the upper side in FIG.

  As described above, the transmission line structure 30 includes the adhesive 36 for bringing the flexible wiring board 31 into close contact with the ground conductor portion 33. Thereby, the precision which the grounding conductor part 33 closely_contact | adheres to the outer surface of the single layer type flexible wiring board 31 can be raised further. Therefore, since the configuration is closer to that of the two-layer flexible wiring board, it is possible to increase the transmission efficiency.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  The present invention can be used in a transmission line structure, an optical pickup, and an optical disc apparatus.

DESCRIPTION OF SYMBOLS 1 Optical disk apparatus 2 Signal processing part 3 Control part 10 Optical pick-up 11 1st laser element (light source)
18 Second laser element (light source)
25 First laser element drive circuit (drive circuit)
26 Second laser element drive circuit (drive circuit)
30 Transmission line structure 31 Flexible wiring board 33 Grounding conductor (grounding conductor)
34, 37 Holding part 35 Groove part 36 Adhesive

Claims (6)

A transmission line structure provided in a device,
A single-layer flexible wiring board including an insulator part and a transmission line provided inside the insulator part;
A ground conductor composed of a conductor portion of the device in close contact with at least one outer surface of the flexible wiring board;
A transmission line structure comprising:   The transmission line structure according to claim 1, further comprising a holding portion that holds the flexible wiring board while pressing the flexible wiring board against the ground conductor.   The transmission line structure according to claim 1, further comprising an adhesive for bringing the flexible wiring board into close contact with the ground conductor.   An optical pickup comprising the transmission line structure according to any one of claims 1 to 3. A light source, and a drive circuit for the light source,
The optical pickup according to claim 4, wherein the transmission line structure is used to electrically connect the light source and the drive circuit.   An optical disc apparatus comprising the transmission line structure according to any one of claims 1 to 3.

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