JPH01138958A - Moving device - Google Patents

Abstract

PURPOSE:To reduce the number of parts as well as the assembling manhours, by a method wherein two pieces of shafts are arranged in parallel to each other so as to be zigzag while one piece of the shafts is served both for the center yoke of a linear motor for driving a carriage and a holding shaft for holding it. CONSTITUTION:A light disc driving device is constituted of a light pick-up 1 equipped with a laser luminous element and the like, a carriage 3 having the light pick-up 1 thereon, a linear DC motor(LDM) 4 and the like. The linear DC motor 4 is constituted of a center shaft 5 having a circular section, disc type side plates 6, 7, a cylindrical yoke 8 and permanent magnets 9. Further, another center shaft 11, having the same constitution as the center shaft 5, is equipped while the center shafts 5, 11 are provided symmetrically in parallel to each other and in zigzag. According to this method, one piece of the shaft 5 serves both for a magnetic yoke and a carriage holding shaft for holding one of the carriages while the other carriage is held on the extension of the shaft.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a moving device for moving an optical read/write device to a desired position in an optical disk drive device or the like.

2. Description of the Related Art In conventional optical disk drives and the like, a structure shown in FIG. 8, for example, is used as a means for moving a pickup section for track switching.

In FIG. 8, 35a.

35b is an optical pickup unit equipped with a light emitting element, a light receiving element, and various optical devices; 36a and 36b are optical pickup units 3;
This is a guide shaft that slidably holds 5a and 35b. Of the optical pickup sections 35a and 35b, for example, if the optical pickup section 35a is used only for erasing, the optical pickup section 35b is used only for writing.

37 is a linear motor for moving the optical pickups H35a and 35b, and two motors are provided, one dedicated to the optical pickup section 35a and the other dedicated to the optical pickup section 35b. 38 is an annular yoke, and the fixing member 3
9 to the chassis 40. Reference numeral 41 is a center yoke provided inside the yoke 38 so as to span the frame. 42 is a plate-shaped permanent magnet fixed to the yoke 38. A coil 43 is fixed to the optical pickup sections 35a and 35b by a connecting member 44. The center yoke 41 passes through the coil 43.

As shown in FIGS. 9(a) and 9(b), the optical pickup portion 35a is precisely fitted with the guide shaft 36a, and its position is accurately regulated, but the optical pickup portion 35a is positioned in the direction of the arrow in relation to the guide shaft 36b. It is only regulated and there is a gap in the direction of arrow J.

The same applies to the optical pickup section 35b.

Problems to be Solved by the Invention In the above configuration, the movement of the optical pickup 135 is regulated by the guide shaft 36a, and therefore the movement of the coil 43 is also indirectly regulated by the guide shaft 36a. By the way, it is necessary for the coil 43 to maintain a non-contact state with the center yoke 41 and the permanent magnet 42, and for this purpose, the relative positional relationship between the guide shaft 36a and the center yoke 41 and the permanent magnet 42 must be made extremely accurate. It is necessary to assemble it. However, in the conventional configuration, the center yoke 41, the permanent magnet 42, and the guide shaft 36a are separately attached to the chassis 40, and there is a limit to how accurate the above positional relationship can be. Therefore, in reality, the gap between the center yoke 41 and the coil 43 and the gap between the permanent magnet 42 and the coil 43 had to be widened to some extent. Increasing these gaps increases the magnetic resistance in the magnetic path and reduces the number of magnetic fluxes interlinking with the coil 43. Therefore, in order not to reduce the driving force of the linear motor 37, Yoke 38, center yoke 41
．． This has the disadvantage that the permanent magnet 42 and the like must be made large, which increases the size accordingly.

The present invention has been made in view of the above-mentioned problems, and provides a moving device that has a simple configuration and uses simple assembly techniques to achieve tight magnetic coupling between the coil and the center shaft, thereby realizing miniaturization of the entire device. The purpose is to provide.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention arranges two carriage holding shafts each having a portion acting as a magnetic yoke at one end in parallel and staggered. Two carriages were arranged symmetrically so that a drive coil provided on one side of each carriage moved the portion acting as the magnetic yoke.

Effect With the above structure, the second shaft serves both as a magnetic yoke and a carriage holding shaft for holding one of the carriages, and further holds the other carriage by extension.

Embodiment Hereinafter, as an embodiment of the mobile device according to the present invention, a case where it is used in an optical disk drive device will be described. Figure 1 is a plan view showing the overall configuration, Figure 2 is line A-A in Figure 1.
FIG. In FIGS. 1 and 2, reference numeral 1 denotes an optical pickup equipped with a laser emitting element, a condensing lens, a beam splitter, a light receiving element, etc., and is configured so that the laser beam emitted from the laser beam irradiation section 2 hits the recording surface of the optical disk. It has become. An optical pickup 1 is installed for recording and reproducing information. 3 is a carriage on which the optical pickup section 1 is mounted. 4 is a linear direct current motor (hereinafter referred to as LDM) for moving the carriage.

The LDM4 will be explained in detail below. 5 is a center shaft with a circular cross section, which is machined to form a precise cylinder. The center shaft 5 is thick on one side and thin on the other side. The thick part of the center shaft 5 is called a large diameter part 5a, and the other thin part is called a small diameter part 5b. The large-diameter portion 5a and the small-diameter portion 5b are cut to form concentric cylinders. Further, an attachment portion 5c for attachment to the chassis is formed at the end of the large diameter portion 5a of the center shaft 5. Since the large diameter part 5a, the small diameter part 5b, and the attachment part 5c are cut by the same lathe, their concentricity is very high.

6 and 7 are disc-shaped steel plates that fit into the center shaft 5, and 8 is a cylindrical yoke that is arranged to wrap around the large diameter portion 5a of the center shaft 5 and is fixed to the side plates 6 and 7. The center shaft 5, side plates 6, 7, and yoke 8 are made of magnetic material. A permanent magnet 9 has a cylindrical shape similar to the yoke 8, and is fixed to the inner surface of the yoke 8. The yoke 8 and the permanent magnet 9 are each cut out on the side, and the carriage 3 is inserted into the open portion, as shown in FIG.

FIG. 4 is a diagram showing the state of assembly. Through holes 6a and 7a are formed in the center of the side plates 6°7, respectively, and the through holes 6a
, 7a respectively, the narrow diameter portion 5b of the shaft 5 and the attachment portion 5c penetrate therethrough.

A tapered surface 5d is formed at the boundary between the large diameter portion 5a and the mounting portion 5c of the shaft 5, and a similar taper surface is formed at the boundary between the large diameter portion 5a and the small diameter portion 5b of the shaft 5. surface(
(not shown in Figure 4) is formed. One side plate 6
A tapered surface 6b is formed around the through hole 6a of the shaft 5 so as to fit with the tapered surface of the shaft 5, and a similar tapered surface (not shown in FIG. 4) is formed around the through hole 7a of the side plate 7. is formed. Through hole 6a during assembly.

7a, the narrow diameter part 5b of the shaft 5 and the mounting part 5, respectively.
c is penetrated, the respective tapered surfaces are brought into close contact, and the side plates 6, 7 and the shaft 5 are fixed by welding or the like while pressing the side plates 6, 7 toward the large diameter portion 5a of the shaft 5. By forming the tapered surfaces on the side plates 6, 7 and the shaft 5 so that both fit together in this way, a very good connection between the shaft 5 and the side plates 6, 7 can be achieved with a simple configuration and a simple assembly method. Magnetic coupling will be obtained.

By the way, in order to move the carriage 3 stably, the center of the center shaft 5 should be made sufficiently thick (it is better).Moreover, if the center of the center shaft 5 is made thick, the magnetic resistance of the center shaft 5 itself □ will decrease accordingly. ,
Furthermore, the tapered surface can also be made wider.

After the side plates 6 and 7 are fixed to the shaft 5, they are inserted into the yoke 8 as shown in FIG. In the state where it is simply inserted, for example, the board 7 can be folded down as shown in FIG.
A gap is created between the outer surface of the yoke 8 and the inner surface of the yoke 8,
Similarly, a gap is created between the outer surface of the side plate 6 and the inner surface of the yoke 8. Therefore, pressure is applied to the yoke 8 as shown by arrows E and F to squeeze the yoke 8, and the side plate 6°7
The outer surface of the yoke 8 is brought into pressure contact with the inner surface of the yoke 8, and the yoke 8 and the side plates 6, 7 are fixed by welding or the like. By doing so, very good magnetic coupling can be obtained between the yoke 8 and the side plates 6 and 7.

Reference numeral 10 denotes a bearing part formed at one end of the carriage 3, and the bearing part 10 of the carriage 3 is slidable on the center shaft 5 and precisely fitted together without any play. Reference numeral 11 denotes a driving coil, and a bearing is provided around the portion 10 so as to wrap around the center shaft 5.

In addition, 12 is an optical pickup section, 14 is a carriage, 1
5 is a linear direct current motor (LDM), and these are the aforementioned optical pickup section 1, carriage 3, and LDM, respectively.
It has the same configuration as 4.

16 is a center shaft configured similarly to the center shaft 5. As described above, the center shaft 5 in the LDM 4 precisely fits with the carriage 3 and guides the carriage 3, but does not have the ability to position the carriage 3 in the direction of arrow B shown in FIG. Therefore, the center shaft 16 and the through hole 17 of the carriage 3 are fitted together to regulate the position in the direction of arrow B. However, the through hole 17 is provided with a margin in the direction of arrow C so that the carriage 3 can move smoothly even if the distance between the center shaft 5 and the center shaft 16 varies. In other words, the position of the carriage 3 in the direction of arrow C is regulated by the center shaft 5. Further, the carriage 14 is also held by the center shaft 16 and the center shaft 5 in a similar manner.

FIG. 6 is an enlarged sectional view taken along line DD shown in FIG. 1. In FIG. 6, 18 is the gap between the large diameter part 5a of the center shaft 5 and the bearing part 10, but as mentioned above, the large diameter part 5a and the bearing part 10 are machined so that they fit precisely. Therefore, the width of the gap 18 is actually very small, and it is filled with lubricating oil. In addition, 19 is the bearing part 1
0 and the permanent magnet 9. The coil 11 is shown in broken lines in this figure.

As described above, the bearing portion 10 is precisely fitted into the center shaft 5, and no displacement occurs in the radial direction. Furthermore, if the center shaft 5 and the permanent magnet 9 are accurately fixed, the bearing that moves on the center shaft 5 will maintain a constant distance between the bearing section 10 and the permanent magnet 9 no matter where the bearing section 10 is located. Can be done. Therefore, the gap 19 can be designed to be quite small. In this way, the gap 18 is extremely small, and the gap 19 can also be made quite small, so the magnetic resistance on the magnetic circuit is reduced accordingly, and the magnetic flux density in the gap 19 can be made very large.

Being able to increase the magnetic flux density also means that the permanent magnets required to obtain a predetermined magnetic flux density can be made smaller, and by configuring it in this way, LDM4 and It becomes possible to make the LDM 15 extremely compact.

Further, the permanent magnet 10 and the yoke 8 are cylindrical so as to correspond to the cylindrical center shaft 5, and the number of magnetic fluxes in the gap 19 is substantially uniform over the entire circumference. Therefore, when a current is passed through the coil 11, the force that the coil receives at each point on the circumference becomes approximately constant. For example, in FIG. 1, the force Fl at the right end and the force F2 at the left end are equal, and the forces applied to the coil at other points on the circumference are also equal. Therefore, when a current is applied to the coil 11, the bearing section 10 tends to move in a direction that coincides with the central axis of the shaft 5, and the large diameter section 10 of the shaft 5
Since a is thick and the diameter of the coil 11 is accordingly large, it is less affected by the inertia of the optical pickup section 1, and the carriage 3 moves relatively stably.

The above also applies to the carriage 14.

In FIGS. 1 and 3, 20 is a chassis that holds each part, 21 and 22 are provided on the chassis 17, and LDM 4
It is a fixing base for fixing.

23 and 24 are similarly provided on the chassis 17, and LDM1
This is a fixing base for fixing 5. When fixing LDM4, attach center shaft 5 to part 5c and narrow diameter part 5.
The ends of b are placed on the fixing bases 21 and 22, respectively, and pressed down with the shaft fixing plate 25. On the other hand, the same applies when fixing the LDM 25, and the center shaft 16 is attached by placing the ends of the portion 26c and the narrow diameter portion 16b on the fixing bases 23 and 24, respectively, and pressing them down with the shaft fixing plate 25.

By the way, the conventional method shown in FIGS. 8 and 9.

In the example configuration, the linear motor 37 is connected to the optical pickup section 3.
5a and 35b, the linear motor 37 has to be arranged parallel to and in series with the movement area of the disks, and the linear motor 37 protrudes largely from the area occupied by the disk. On the other hand, disk 45 and chassis 4
0 (both optical pickup sections 35a and 35
Although it is necessary to keep a width corresponding to the thickness of b, this results in unnecessary space being formed around the guide shafts 36a and 36b.In this way, in the conventional configuration, the linear motor 37 largely protrudes from the area occupied by the disk 45, and wasteful dead space is formed around the guide shafts 36a and 36b within the area occupied by the disk 45, making it impossible to effectively utilize the space. .

In FIG. 1, E is an imaginary line indicating an optical disc to be loaded into the present optical disc drive device. In this way, in this embodiment, the LDM 4 is arranged to the side of the optical pickup 1, and most of the LDM 4 is included in the area occupied by the optical disk, so compared to the configuration shown in the conventional example. It is also possible to make the entire device relatively compact.

FIG. 7 is a block diagram showing the position control means of the LDM 4. The optical pickup 1 converts reflected light from an optical disk 27 rotated by a spindle motor 26 into an electrical signal and sends it to a position detector 28 .

The position detector 28 detects the number of the track on which the laser spot is hitting from the sent signal. Drive circuit 2
9 includes an external signal for commanding the target track number;
After comparing the track number of the track currently hit by the laser spot sent from the position detector 28, an appropriate drive current is applied to the LDM 4 or LDM 15.

Effects of the Invention As described above, the present invention has two shafts, one end of which is formed with a part that only functions to hold the carriage, and the other end of which is formed with a part that functions as a magnetic yoke in addition to holding the carriage. By arranging the two carriages symmetrically so that the drive coil provided on one side of each moves the part that acts as the magnetic yoke, the - shaft is connected to the center yoke of the linear motor for driving the carriage. It also serves as a holding shaft that holds both carriages. Additionally, the center yoke of the linear motor is directly fixed to the chassis, which holds the carriage. Therefore, the magnetic coupling between the coil on the carriage and the center yoke is very tight, and there is no need to separately provide a dedicated shaft to hold the carriage (the number of parts can be reduced, and the number of assembly steps can also be reduced. Since the drive coil moves guided by the center yoke itself, if a field means such as a permanent magnet and a yoke is attached to the center yoke so that there is no variation in positional relationship, the center yoke and the permanent magnet and yoke can be connected to each other. The distance of the magnetic gap can be made extremely narrow, that is, the magnetic resistance in the magnetic path can be reduced and the number of separated fluxes can be increased, so that the yoke and permanent magnets necessary to obtain the desired driving force can be can be made smaller, and the whole can be made smaller.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a moving device according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line A-A in FIG. 1, and FIG. 3 is a cross-sectional view taken along line A-A in FIG. 4 is an exploded perspective view of the linear motor of the moving device, FIG. 5 is a perspective view of the main parts of the linear motor, and FIG. 6 is a view taken along line D-D in FIG. 1. 7 is a block diagram of the drive circuit of the same moving device, FIG. 8 is a plan view of the conventional moving device, FIG. 9 (A) is an enlarged view of the same moving device, and FIG. 9 (B)
is a side view of the same moving device. 1.13... Optical pickup 3.14... Carriage 4.15... Linear motor (LDM) 5.16...
...Center shaft 6.7...Side plates 6a, 7a...Through hole 8...Yoke 9...Permanent magnet 11...
... Name of drive coil agent Patent attorney Toshio Nakao and one other person Figure 1 Figure 2 Figure 3 Figure 4 Figure 6 Figure 9

Claims (1)

[Claims] The first part is made of magnetic material and has a carriage holding function.
two shafts having a section and a second section having a magnetic yoke function as well as a carriage holding function are arranged parallel to each other, and the first section of one shaft and the second section of the other shaft are opposed to each other. two carriages fixed on the chassis in a staggered manner and provided with bearing means at both ends for receiving said shaft, the bearing means at one end being located in the first section of the shaft and the bearing means at the other end being provided with bearing means for receiving said shaft; Both carriages are slidably held on both shafts such that the carriages are located in the second section of the shaft, and field means for magnetizing the second section of the shaft is provided on both shafts, and both carriages are A driving coil is provided above the shaft so as to surround the second section of the shaft, and a driving means is provided for detecting the position of the carriage and passing a current through the driving coil so that the carriage comes to a desired position. A mobile device characterized by: