Patent Application
20110258646
This application claims priority from Japanese Patent Application Number JP 2010-093145 filed on Apr. 14, 2010, the content of which is incorporated herein by reference in its entirety.
1. Field of the Invention
The invention relates to an optical pickup supporting device for moving an optical pickup device, which is configured to perform a reading operation and a recording operation on an optical disc, in a predetermined direction, and an optical disc apparatus including the same.
2. Description of the Related Art
Widely used are optical disc apparatuses each capable of performing a signal reading operation and a signal recording operation by casting laser light emitted from the optical pickup device on a signal recording surface of the optical disc.
In general, widely-used optical disc apparatuses are of a type using optical discs which are termed as compact discs (CDs) and digital versatile discs (DVDs). Recently, optical disc apparatuses of a type which uses optical discs in compliance with the Blu-ray standard for making the recording density much higher have been developed.
An optical pickup device installed in an optical disc apparatus is configured to be moved in a radial direction of an optical disc by a rotational driving force of a pickup feeding motor. In addition, such an optical pickup device is required to accurately read signals which are recorded in the optical disc. To this end, the optical pickup device is required to precisely carry out its own moving operation in the radial direction of the optical disc. For this reason, the optical pickup device is generally constructed in a way that its moving operation is guided by a pair of guide shafts fixed to a fixation board. (This technology is described in Japanese Patent Application Publication No. Hei 11-66767.)
Furthermore, the positions of the respective guide shafts are held by a frame-shaped chassis formed from a metal plate (this technology is described in Japanese Patent Application Publication No. 2003-208767). To put it specifically, referring to FIG. 1A of Japanese Patent Application Publication No. 2003-208767, the two near-end portions of each of the two guide shafts are fixed to a chassis 11 while adjusted to their respective predetermined positions by use of fastening means such as screw mechanisms. Because the guide shafts are attached to the chassis with the fine adjustment applied to the guide shafts by use of the screws, the optical pickup device is capable of performing the reading operation and the recording operation accurately.
The foregoing optical disc apparatuses include those using the various types of optical discs, such as a CD standard optical disc, a DVD standard optical disc and a Blu-ray standard optical disc, as described above. Furthermore, such optical disc apparatuses include those of a stationary type and those of a type installed in computer apparatuses.
Among personal computers, particularly, note-type computers are made thinner. Accordingly, optical disc apparatuses of a type installed in such computers are made thinner as well. When optical disc apparatuses are made thinner, optical pickup devices installed in the optical disc apparatuses are also required to be made thinner.
In addition, Blu-ray standard optical disc apparatuses capable of performing a higher-density recording operation have recently become widely in use. Optical pickup devices installed in such optical disc apparatuses are required not only to have higher precision in itself, but also to secure higher movement accuracy for a driving mechanism configured to perform displacement operations in the radial direction.
A mechanism for fixing the guide shafts to the chassis formed from a metal plate by pressing the guide shafts by use of plate springs has been heretofore adopted as a method of securing positional accuracy for this movement mechanism. However, this mechanism allows vibrations, which occur from a motor configured to move a pickup, to be transmitted to the optical pickup device via the chassis and the guide shafts. This makes the optical pickup device likely to malfunction due to the vibrations.
Moreover, this structure needs plate springs and screw mechanisms for fixing the guide shafts to the chassis in addition to the chassis. The use of these parts increases the number of parts and the number of steps included in the manufacturing process.
Accordingly, when the chassis of the optical disc apparatus is formed from a metal plate whose thickness is approximately 1 mm, the optical disc apparatus in itself is likely to become heavier in weight.
The invention has been made with these problems taken into consideration. An object of the invention is to provide a low-cost, high accuracy optical pickup supporting device by simplifying a structure for fixing the guide shafts to the chassis, and an optical disc apparatus including the same.
An optical pickup supporting device according to the present invention comprises: a chassis; an optical pickup device for casting laser light on an optical recording medium, and detecting the laser light reflected off the optical recording medium; a first guide shaft inserted through a guide hole provided in the optical pickup device, two near-end portions of the first guide shaft being fixed to the chassis; a second guide shaft inserted through a guide groove provided in the optical pickup device, two near-end portions of the second guide shaft being fixed to the chassis; and a motor supporting member for rotatably fixing a spindle motor to the chassis, the spindle motor being configured to rotate the optical recording medium, wherein one of the two near-end portions of the first guide shaft is pressingly fixed to a position regulating portion by use of a fixation area continuing integrally with the chassis, the position regulating portion provided in the motor supporting member.
In the optical pickup supporting device of the embodiment of the invention, one near-end portion of the first guide shaft for movably supporting the optical pickup device is pressingly fixed to the position regulating portion of the motor supporting member by use of the fixation area continuing integrally with the chassis, the motor supporting member provided for supporting the motor. Thereby, the part of the chassis has a role of fixing the guide shaft to the chassis, and makes the above-mentioned plate spring or screw mechanism for fixing the guide shafts no longer necessary. As a result, the parts and manufacturing steps are reduced in number, and the costs reduction can be accordingly achieved.
Furthermore, in the embodiment of the invention, the chassis and the fixation area are integrally injection-molded out of a resin material. Thereby, the guide shaft is lightly pressed to the position regulating portion of the motor supporting member by the fixation area formed from the resin material which is more flexible than a metal material. As a result, vibrations caused by the rotation of the motor are absorbed by this fixation area, and the vibrations are thus restrained from being transmitted to the optical pickup device. This stabilizes the operation of the optical pickup device.
Moreover, because the chassis which is a main component of the optical pickup supporting device is formed from the resin material which is light in weight, the optical pickup supporting device as a whole is made lighter in weight than any optical pickup supporting device of the conventional example in which the chassis is formed from a metal plate.
Additionally, the position of the first guide shaft is determined by the position regulating portion provided in the motor supporting member connected to the motor. This much enhances the positional accuracy between the first guide shaft and the motor.
Referring to
Referring to
The optical pickup supporting device 10 projects laser light on an optical disc (an optical recording medium) rotated by the spindle motor 34 through the objective lens 32 of the optical pickup device 30. Subsequently, the optical pickup supporting device 10 reads laser light reflected off an information recording layer of the optical disc by use of a photodiode integrated circuit (PDIC) built in the optical pickup device 30. In this respect, laser light in compliance with the Blu-ray disc (BD) standard, the digital versatile disc (DVD) standard or the compact disc (CD) standard is adopted as the laser light to be emitted from the optical pickup device. Similarly, any one of these standards is adopted as a standard for the optical disc rotated by the spindle motor 34.
An optical disc apparatus is made up by housing the thus-configured optical pickup supporting device 10 in a case formed in a predetermined shape.
The chassis 12 is injection-molded out of a resin material, and is shaped like a frame. The chassis 12 has a function of integrally supporting the constituent elements of the optical pickup supporting device 10. A polycarbonate, a modified-PPE (polyphenylene ether) or an acrylonitrile butadiene styrene (ABS) resin is used as the resin material to be made into the chassis 12. Otherwise, a resin material filled with glass fibers may be used as the material of the chassis 12. Incidentally, the four corners of the chassis 12 are provided with the respective cut-away portions for mounting the chassis 12 on a case of the optical disc apparatus by use of fastening means such as screws.
The first guide shaft 14 and the second guide shaft 16 are members for supporting the optical pickup device 30 movably in a radial direction of the optical disc. To this end, the first guide shaft 14 and the second guide shaft 16 are arranged in parallel to the radial direction of the optical disc in a plan view, and concurrently in parallel to an information recording surface of the optical disc as well. It should be noted that the first guide shaft 14 and the second guide shaft 16 are made of a bar-shaped metal material such as a stainless steel. In this respect, the first guide shaft 14 and the second guide shaft 16 will be respectively referred to as a “main guide shaft” and an “auxiliary guide shaft” from time to time.
The two near-end portions of the first guide shaft 14 are attached to the chassis 12 by use of a first fixation region 22 and a second fixation region 24, respectively. The two near-end portions of the second guide shaft 16 are attached to the chassis 12 by use of a third fixation region 26 and a fourth fixation region 28, respectively.
Referring to
The spindle motor 34 has a function of rotating the optical disc, which is held by a chucking mechanism, at a predetermined speed. The spindle motor 34 is fixed to the chassis 12 with the motor supporting member 36, which is formed from a metal plate in a predetermined shape, interposed in between. Incidentally, the spindle motor 34 is fixed to the motor supporting member 36 rotatably about its rotary axis.
In the optical pickup device 30, a light-emitting chip, a light-receiving chip and the other optical elements are accommodated inside a housing which is molded out of a resin in a predetermined shape. Two near-end portions of the housing of the optical pickup device 30 are held movable in the radial direction of the optical disc by the first guide shaft 14 and the second guide shaft 16. Detailed descriptions will be later provided for this holding mechanism while referring to
Referring to
Referring to
The guide hole 18 is a hole portion provided by integrally injection-molding the housing 46 and the guide hole 18 out of a resin material. The first guide shaft 14 is inserted in the guide hole 18. The guide hole 18 not only supports the optical pickup device 30 while allowing the optical pickup device 30 to move in the radial direction of the optical disc, but also has a function of restraining the optical pickup device 30 from moving in a direction orthogonal to this radial direction. To this end, the inner diameter of the guide hole 18 is set large enough for the guide hole 18 to allow the optical pickup device 30 to move in a direction along the first guide shaft 14, and concurrently to restrain the optical pickup device 30 from rattling.
It should be noted that the various optical elements accommodated in the housing 46 are connected to a main circuit board built in the case of the optical disc apparatus via the connector 44 and a flexible wiring board (not illustrated).
The guide groove 20 is provided in an end portion of the housing 46, which is opposed to the guide hole 18. The guide groove 20 is shaped like the letter U or a square bracket, and is opened outward. The second guide shaft 16 engages with or is inserted in the guide groove 20.
Next, referring to
Referring to
Referring to
A rotor 64 is fittingly fixed to the rotary shaft 58, and rotates integrally with the rotary shaft 58. Furthermore, a ring-shaped magnet 66 is adhesively fixed to the inner surface of the rotor 64. A turntable 62 constitutes a surface which the main surface of the optical disc is in contact with. The turntable 62 rotates together with the rotor 64. A centering member 60 has a chucking function. When a hole portion provided in the center portion of the optical disc is fitted to the centering member 60, a position of the optical disc in the direction of the main surface is defined as a predetermined position.
In the thus-configured spindle motor 34, once a drive signal is supplied to the driving coils 68 from a motor driving circuit installed in the motor board 56 and the like, a rotary force to be applied to the rotor 64 is generated by a magnetic force induced from the driving coils 68 and a magnetic force produced from the magnet 66. By this, the rotor 64 rotates about the rotary shaft 58.
Once the rotary shaft 58 rotates due to the rotary driving force produced in the rotor 64, the turntable 62 fittingly fixed to the rotary shaft 58 rotates. Accordingly, the optical disc placed on the turntable 62 can be rotated. Subsequently, when the amplitude of the drive signal supplied to the driving coils 68 and the interval of drive pulses supplied to the driving coils 68 are controlled, the rotational speed of the optical disc can be controlled in order to set the rotational speed thereof at a desired rotational speed.
Referring to
In this configuration, the position of the turntable 62 is determined by the bearing 72 fixedly attached to the rotary shaft supporting member 70 which is fixed to the recess portion formed in the motor supporting member 36. On the other hand, the position of the first guide shaft 14 for positioning the optical pickup device is regulated by the position regulating portion 52 which is a part of the motor supporting member 36. Thus, the position of the spindle motor 34 and the position of the first guide shaft 14 are regulated by the motor supporting member 36 which is the single continuous metal plate. This much enhances the relative positional accuracy between the spindle motor 34 and the first guide shaft 14 in the vertical direction and the left-right direction as shown on the sheet on which the drawing is made. Accordingly, the relationship between the optical pickup device whose movement position is regulated by the first guide shaft 14 and the optical disc placed on the turntable 62 rotationally driven by the rotary shaft 58 are maintained in an optimal condition.
Referring to
Referring to
To put is specifically, the fixation area 78 includes a first fixation member 80, a guide portion 84, a second fixation member 82 and a contact member 86. The first fixation member 80 and the second fixation member 82 pressingly fixes the first guide shaft 14 to the position regulating portion 52 of the motor supporting member 36 by use of repulsive forces produced by their own deformation.
The guide portion 84 is shaped like the letter L which is placed upside down, and is arranged adjacent to the first fixation member 80. The guide portion 84 has a function of facilitating the insertion of the first guide shaft 14 during the manufacturing step. In addition, for the purpose of inserting the first guide shaft 14 smoothly, as shown in
The second fixation member 82 is a member obtained by protruding a part of the main surface of the chassis 12, which corresponds to a part through which the first guide shaft 14 is inserted. The second fixation member 82 is placed in a region interposed between the guide portion 84 and the contact portion 86. The second fixation member 82 gives a pressing force to the first guide shaft 14 from under.
The contact portion 86 is a member for positioning the first guide shaft 14 when the front end portion of the first guide shaft 14 comes into contact with the contact portion 86. The positioning of the first guide shaft 14 in its axial direction is achieved by the contact portion 86.
A method of mounting these components on the chassis 12 is as follows.
First of all, the motor unit 50 is fixedly attached to the chassis 12 by use of screws inserted through the respective hole portions provided in the motor supporting member 36. Thereby, the position regulating portion 52 formed from the part of the motor supporting member 36 which is a metal plate, and the fixation area 78 of the chassis 12 injection-molded out of the resin material are stacked together in the first fixation region 22 in the direction of the axis of the first guide shaft 14.
Subsequently, the first guide shaft 14 is inserted through the guide hole 18 of the optical pickup device 30. Thereafter, the end portion of the first guide shaft 14 is inserted through the fixation area 78 and the position regulating portion 52. This insertion brings the front end portion of the first guide shaft 14 into contact with the contact portion 86 of the chassis 12, and makes the end portion of the first guide shaft 14 fixed to the first fixation region 22.
Referring to
As shown in this drawing, the mechanisms with which the guide shafts are fixed to the chassis in the second fixation region 24 to the fourth fixation region 28 are different from the mechanism with which the guide shaft is fixed to the chassis in the first fixation region 22. In the first fixation region 22, the first guide shaft 14 is fixed to the predetermined position by the repulsive force produced by the protruding portion of the chassis 12. In the second fixation region 24 to the fourth fixation region 28, the guide shafts are fixed to the chassis 12 by the fastening mechanisms such as the screws. Furthermore, the positions of the guide shafts are adjusted by rotating the screws in order that the running plane of the optical pickup device 30 which is made by the first guide shaft 14 and the second guide shaft 16 can be in parallel to the main surface of the optical disc rotated by the spindle motor 34. When this adjustment is performed, the first fixation region 22 to which the first guide shaft 14 is already fixed is used as the reference point.
Through the foregoing steps, the first guide shaft 14 and the second guide shaft 16 are fixed to the respective predetermined positions of the chassis 12.
Referring to
Referring to
Moreover, as shown in
In the embodiment, as described above, the position of the first guide shaft 14 is fixed by use of the repulsive force produced by the elastic deformation or the plastic deformation of the fixation area 78 formed from the flexible resin material. Accordingly, referring to
Moreover, in the embodiment, the position of the end portion of the first guide shaft 14 is regulated by the position regulating portion 52 formed from the metal plate. The position regulating portion 52 formed from the metal plate has a higher mechanical strength and a smaller coefficient of thermal expansion than the chassis 12 formed from the resin material. Accordingly, the position of the first guide shaft 14 is regulated more accurately.
Additionally, the position regulating portion 52 for regulating the position of the first guide shaft 14 is the part of the motor supporting member 36, and the spindle motor 34 is fixed to this motor supporting member 36. Accordingly, the position of the spindle motor 34 and the position of the first guide shaft 14 are accurately regulated by the single metal plate. This enhances the relative positional accuracy between the optical disc rotated by the spindle motor 34 and the optical pickup device whose position is determined by the first guide shaft 14.
Furthermore, the fixation area 78 is the part of the chassis 12, and the position regulating portion 52 is the part of the motor supporting member 36. This makes it possible to regulate the position of the first guide shaft 14 with higher accuracy by use of no specialized parts.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-093145 | Apr 2010 | JP | national |
